Two-phase motors are rarely used except in special-purpose equipment. They are discussed here to aid in understanding rotating fields. You will, however, encounter many single-phase and three-phase motors.
Q5. What is the angular displacement between field poles in a two-phase motor stator?
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The three-phase induction motor also operates on the principle of a rotating magnetic field. The following discussion shows how the stator windings can be connected to a three-phase ac input and have a resultant magnetic field that rotates.
Figure 4-4, views A-C show the individual windings for each phase. Figure 4-4, view D, shows how the three phases are tied together in a Y-connected stator. The dot in each diagram indicates the common point of the Y-connection. You can see that the individual phase windings are equally spaced around the stator. This places the windings 120º apart.
The three-phase input voltage to the stator of figure 4-4 is shown in the graph of figure 4-5. Use the left-hand rule for determining the electromagnetic polarity of the poles at any given instant. In applying the rule to the coils in figure 4-4, consider that current flows toward the terminal numbers for positive voltages, and away from the terminal numbers for negative voltages.
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The results of this analysis are shown for voltage points 1 through 7 in figure 4-5. At point 1, the magnetic field in coils 1-1A is maximum with polarities as shown. At the same time, negative voltages are being felt in the 2-2A and 3-3A windings. These create weaker magnetic fields, which tend to aid the 1-1A field. At point 2, maximum negative voltage is being felt in the 3-3A windings. This creates a strong magnetic field which, in turn, is aided by the weaker fields in 1-1A and 2-2A. As each point on the voltage graph is analyzed, it can be seen that the resultant magnetic field is rotating in a clockwise direction. When the three-phase voltage completes one full cycle (point 7), the magnetic field has rotated through 360º .
Q6. What is the major difference between a two-phase and a three-phase stator? ROTOR BEHAVIOR IN A ROTATING FIELD
For purposes of explaining rotor movement, let's assume that we can place a bar magnet in the center of the stator diagrams of figure 4-5. We'll mount this magnet so that it is free to rotate in this area. Let's also assume that the bar magnet is aligned so that at point 1 its south pole is opposite the large N of the stator field.
You can see that this alignment is natural. Unlike poles attract, and the two fields are aligned so that they are attracting. Now, go from point 1 through point 7. As before, the stator field rotates clockwise. The bar magnet, free to move, will follow the stator field, because the attraction between the two fields
4-8
continues to exist. A shaft running through the pivot point of the bar magnet would rotate at the same speed as the rotating field. This speed is known as synchronous speed. The shaft represents the shaft of an operating motor to which the load is attached.
Remember, this explanation is an oversimplification. It is meant to show how a rotating field can cause mechanical rotation of a shaft. Such an arrangement would work, but it is not used. There are limitations to a permanent magnet rotor. Practical motors use other methods, as we shall see in the next paragraphs.
pole alternator. In fact, such an alternator may be run as an ac motor. It is similar to the drawing in figure 4-6. Synchronous motors have the characteristic of constant speed between no load and full load. They are capable of correcting the low power factor of an inductive load when they are operated under certain conditions. They are often used to drive dc generators. Synchronous motors are designed in sizes up to thousands of horsepower. They may be designed as either single-phase or multiphase machines. The discussion that follows is based on a three-phase design.
To understand how the synchronous motor works, assume that the application of three-phase ac power to the stator causes a rotating magnetic field to be set up around the rotor. The rotor is energized with dc (it acts like a bar magnet). The strong rotating magnetic field attracts the strong rotor field activated by the dc. This results in a strong turning force on the rotor shaft. The rotor is therefore able to turn a load as it rotates in step with the rotating magnetic field.
It works this way once it’s started. However, one of the disadvantages of a synchronous motor is that it cannot be started from a standstill by applying three-phase ac power to the stator. When ac is applied to the stator, a high-speed rotating magnetic field appears immediately. This rotating field rushes past the rotor poles so quickly that the rotor does not have a chance to get started. In effect, the rotor is repelled first in one direction and then the other. A synchronous motor in its purest form has no starting torque. It has torque only when it is running at synchronous speed.
A squirrel-cage type of winding is added to the rotor of a synchronous motor to cause it to start. The squirrel cage is shown as the outer part of the rotor in figure 4-7. It is so named because it is shaped and looks something like a turnable squirrel cage. Simply, the windings are heavy copper bars shorted
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together by copper rings. A low voltage is induced in these shorted windings by the rotating three-phase stator field. Because of the short circuit, a relatively large current flows in the squirrel cage. This causes a magnetic field that interacts with the rotating field of the stator. Because of the interaction, the rotor begins to turn, following the stator field; the motor starts. We will run into squirrel cages again in other applications, where they will be covered in more detail.
To start a practical synchronous motor, the stator is energized, but the dc supply to the rotor field is not energized. The squirrel-cage windings bring the rotor to near synchronous speed. At that point, the dc field is energized. This locks the rotor in step with the rotating stator field. Full torque is developed, and the load is driven. A mechanical switching device that operates on centrifugal force is often used to apply dc to the rotor as synchronous speed is reached.
The practical synchronous motor has the disadvantage of requiring a dc exciter voltage for the rotor. This voltage may be obtained either externally or internally, depending on the design of the motor.
Q7. What requirement is the synchronous motor specifically designed to meet?
INDUCTION MOTORS The induction motor is the most commonly used type of ac motor. Its simple, rugged construction
costs relatively little to manufacture. The induction motor has a rotor that is not connected to an external source of voltage. The induction motor derives its name from the fact that ac voltages are induced in the rotor circuit by the rotating magnetic field of the stator. In many ways, induction in this motor is similar to the induction between the primary and secondary windings of a transformer.
Large motors and permanently mounted motors that drive loads at fairly constant speed are often induction motors. Examples are found in washing machines, refrigerator compressors, bench grinders, and table saws.
The stator construction of the three-phase induction motor and the three-phase synchronous motor are almost identical. However, their rotors are completely different (see fig. 4-8). The induction rotor is made of a laminated cylinder with slots in its surface. The windings in these slots are one of two types (shown in fig. 4-9). The most common is the squirrel-cage winding. This entire winding is made up of
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heavy copper bars connected together at each end by a metal ring made of copper or brass. No insulation is required between the core and the bars. This is because of the very low voltages generated in the rotor bars. The other type of winding contains actual coils placed in the rotor slots. The rotor is then called a wound rotor.
Regardless of the type of rotor used, the basic principle is the same. The rotating magnetic field generated in the stator induces a magnetic field in the rotor. The two fields interact and cause the rotor to
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turn. To obtain maximum interaction between the fields, the air gap between the rotor and stator is very small.
As you know from Lenz’s law, any induced emf tries to oppose the changing field that induces it. In the case of an induction motor, the changing field is the motion of the resultant stator field. A force is exerted on the rotor by the induced emf and the resultant magnetic field. This force tends to cancel the relative motion between the rotor and the stator field. The rotor, as a result, moves in the same direction as the rotating stator field.
It is impossible for the rotor of an induction motor to turn at the same speed as the rotating magnetic field. If the speeds were the same, there would be no relative motion between the stator and rotor fields; without relative motion there would be no induced voltage in the rotor. In order for relative motion to exist between the two, the rotor must rotate at a speed slower than that of the rotating magnetic field. The. difference between the speed of the rotating stator field and the rotor speed is called slip. The smaller the slip, the closer the rotor speed approaches the stator field speed.
The speed of the rotor depends upon the torque requirements of the load. The bigger the load, the stronger the turning force needed to rotate the rotor. The turning force can increase only if the rotor- induced emf increases. This emf can increase only if the magnetic field cuts through the rotor at a faster rate. To increase the relative speed between the field and rotor, the rotor must slow down. Therefore, for heavier loads the induction motor turns slower than for lighter loads. You can see from the previous statement that slip is directly proportional to the load on the motor. Actually only a slight change in speed is necessary to produce the usual current changes required for normal changes in load. This is because the rotor windings have such a low resistance. As a result, induction motors are called constant-speed motors.
Q8. Why is the ac induction motor used more often than other types? Q9. The speed of the rotor is always somewhat less than the speed of the rotating field. What is the
difference called? Q10. What determines the amount of slip in an induction motor?
There are probably more single-phase ac induction motors in use today than the total of all the other types put together.
It is logical that the least expensive, lowest maintenance type of ac motor should be used most often. The single-phase ac induction motor fits that description.
Unlike polyphase induction motors, the stator field in the single-phase motor does not rotate. Instead it simply alternates polarity between poles as the ac voltage changes polarity.
Voltage is induced in the rotor as a result of magnetic induction, and a magnetic field is produced around the rotor. This field will always be in opposition to the stator field (Lenz’s law applies). The interaction between the rotor and stator fields will not produce rotation, however. The interaction is shown by the double-ended arrow in figure 4-10, view A. Because this force is across the rotor and through the pole pieces, there is no rotary motion, just a push and/or pull along this line.
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Now, if the rotor is rotated by some outside force (a twist of your hand, or something), the push-pull along the line in figure 4-10, view A, is disturbed. Look at the fields as shown in figure 4-10, view B. At this instant the south pole on the rotor is being attracted by the left-hand pole. The north rotor pole is being attracted to the right-hand pole. All of this is a result of the rotor being rotated 90º by the outside force. The pull that now exists between the two fields becomes a rotary force, turning the rotor toward magnetic correspondence with the stator. Because the two fields continuously alternate, they will never actually line up, and the rotor will continue to turn once started. It remains for us to learn practical methods of getting the rotor to start.
There are several types of single-phase induction motors in use today. Basically they are identical except for the means of starting. In this chapter we will discuss the split-phase and shaded-pole motors; so named because of the methods employed to get them started. Once they are up to operating speed, all single-phase induction motors operate the same.
Q11. What type of ac motor is most widely used? Split-Phase Induction Motors
One type of induction motor, which incorporates a starting device, is called a split-phase induction motor. Split-phase motors are designed to use inductance, capacitance, or resistance to develop a starting torque. The principles are those that you learned in your study of alternating current.
CAPACITOR-START.—The first type of split-phase induction motor that will be covered is the capacitor-start type. Figure 4-11 shows a simplified schematic of a typical capacitor-start motor. The stator consists of the main winding and a starting winding (auxiliary). The starting winding is connected in parallel with the main winding and is placed physically at right angles to it. A 90-degree electrical
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phase difference between the two windings is obtained by connecting the auxiliary winding in series with a capacitor and starting switch. When the motor is first energized, the starting switch is closed. This places the capacitor in series with the auxiliary winding. The capacitor is of such value that the auxiliary circuit is effectively a resistive-capacitive circuit (referred to as capacitive reactance and expressed as XC). In this circuit the current leads the line voltage by about 45º (because X C about equals R). The main winding has enough resistance-inductance (referred to as inductive reactance and expressed as XL) to cause the current to lag the line voltage by about 45º (because X
L about equals R). The currents in each winding are therefore 90º out of phase - so are the magnetic fields that are generated. The effect is that the two windings act like a two-phase stator and produce the rotating field required to start the motor.
When nearly full speed is obtained, a centrifugal device (the starting switch) cuts out the starting winding. The motor then runs as a plain single-phase induction motor. Since the auxiliary winding is only a light winding, the motor does not develop sufficient torque to start heavy loads. Split-phase motors, therefore, come only in small sizes.
RESISTANCE-START.—Another type of split-phase induction motor is the resistance-start motor. This motor also has a starting winding (shown in fig. 4-12) in addition to the main winding. It is switched in and out of the circuit just as it was in the capacitor-start motor. The starting winding is positioned at right angles to the main winding. The electrical phase shift between the currents in the two windings is obtained by making the impedance of the windings unequal. The main winding has a high inductance and a low resistance. The current, therefore, lags the voltage by a large angle. The starting winding is designed to have a fairly low inductance and a high resistance. Here the current lags the voltage by a smaller angle. For example, suppose the current in the main winding lags the voltage by 70º. The current in the auxiliary winding lags the voltage by 40º. The currents are, therefore, out of phase by 30º. The magnetic fields are out of phase by the same amount. Although the ideal angular phase difference is 90º for maximum starting torque, the 30-degree phase difference still generates a rotating field. This supplies enough torque to start the motor. When the motor comes up to speed, a speed-controlled switch disconnects the starting winding from the line, and the motor continues to run as an induction motor. The starting torque is not as great as it is in the capacitor-start.
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Q12. How do split-phase induction motors become self-starting? Shaded-Pole Induction Motors
The shaded-pole induction motor is another single-phase motor. It uses a unique method to start the rotor turning. The effect of a moving magnetic field is produced by constructing the stator in a special way. This motor has projecting pole pieces just like some dc motors. In addition, portions of the pole piece surfaces are surrounded by a copper strap called a shading coil. A pole piece with the strap in place is shown in figure 4-13. The strap causes the field to move back and forth across the face of the pole piece. Note the numbered sequence and points on the magnetization curve in the figure. As the alternating stator field starts increasing from zero (1), the lines of force expand across the face of the pole piece and cut through the strap. A voltage is induced in the strap. The current that results generates a field that opposes the cutting action (and decreases the strength) of the main field. This produces the following actions: As the field increases from zero to a maximum at 90º , a large portion of the magnetic lines of force are concentrated in the unshaded portion of the pole (1). At 90º the field reaches its maximum value. Since the lines of force have stopped expanding, no emf is induced in the strap, and no opposing magnetic field is generated. As a result, the main field is uniformly distributed across the pole (2). From 90º to 180º , the main field starts decreasing or collapsing inward. The field generated in the strap opposes the collapsing field. The effect is to concentrate the lines of force in the shaded portion of the pole face (3). You can see that from 0º to 180º , the main field has shifted across the pole face from the unshaded to the shaded portion. From 180º to 360º , the main field goes through the same change as it did from 0º to 180º ; however, it is now in the opposite direction (4). The direction of the field does not affect the way the shaded pole works. The motion of the field is the same during the second half-cycle as it was during the first half of the cycle.
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The motion of the field back and forth between shaded and unshaded portions produces a weak torque to start the motor. Because of the weak starting torque, shaded-pole motors are built only in small sizes. They drive such devices as fans, clocks, blowers, and electric razors.
Q13. Why are shaded-pole motors used to drive only very small devices? Speed of Single-Phase Induction Motors
The speed of induction motors is dependent on motor design. The synchronous speed (the speed at which the stator field rotates) is determined by the frequency of the input ac power and the number of poles in the stator. The greater the number of poles, the slower the synchronous speed. The higher the frequency of applied voltage, the higher the synchronous speed. Remember, however, that neither frequency nor number of poles are variables. They are both fixed by the manufacturer.
The relationship between poles, frequency, and synchronous speed is as follows:
where n is the synchronous speed in rpm, f is the frequency of applied voltage in hertz, and p is the number of poles in the stator.
Let’s use an example of a 4-pole motor, built to operate on 60 hertz. The synchronous speed is determined as follows:
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Common synchronous speeds for 60-hertz motors are 3600, 1800, 1200, and 900 rpm, depending on the number of poles in the original design.
As we have seen before, the rotor is never able to reach synchronous speed. If it did, there would be no voltage induced in the rotor. No torque would be developed. The motor would not operate. The difference between rotor speed and synchronous speed is called slip. The difference between these two speeds is not great. For example, a rotor speed of 3400 to 3500 rpm can be expected from a synchronous speed of 3600 rpm.
SUMMARY This chapter introduced you to the basic principles concerning ac motors. While many variations of
types exist, the three types presented provide you with background for further study if you require more extensive knowledge of the subject. The following information provides a summary of the major subjects of this chapter for your review.
The three AC MOTOR TYPES presented are the series, synchronous, and induction ac motors.
AC SERIES MOTORS are nearly identical to the dc series motors. Special construction techniques allow ac series motors to be used as UNIVERSAL MOTORS, operating on either ac or dc power.
ROTATING FIELDS are developed by applying multiphase voltages to stator windings, which consist of multiple field coils. This rotating magnetic field causes the rotor to be pushed and pulled because of interaction between it and the rotor’s own field.
TWO-PHASE ROTATING FIELDS require two pairs of field coils displaced by 90º . They must be energized by voltages that also have a phase displacement of 90º .
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THREE-PHASE ROTATING FIELDS require three pairs of windings 120º apart, energized by voltages that also have a 120-degree phase displacement.
SYNCHRONOUS MOTORS are specifically designed to maintain constant speed, with the rotor synchronous to the rotating field. Synchronous motors require modification (such as squirrel-cage windings) to be self-starting.
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INDUCTION MOTORS are the most commonly used of all electric motors due to their simplicity and low cost. Induction motors may be single-phase or multiphase. They do not require electrical rotor connection. Split-phase motors with special starting windings, and shaded-pole motors, are types of single-phase induction motors.
SYNCHRONOUS SPEED is the speed of stator field rotation. It is determined by the number of poles and the frequency of the input voltage. Thus, for a given motor, synchronous speed is constant.
SLIP is the difference between actual rotor speed and the synchronous speed in induction motors. Slip must exist for there to be torque at the rotor shaft.
ANSWERS TO QUESTIONS Q1. THROUGH Q13. A1. Series, synchronous, induction.
A2. To power small appliances.
A3. They operate on either ac or dc.
A4. The number of phases in the applied voltage. A5. 90º .
A6. Number and location of field poles. A7. Constant speed required by some loads.
A8. They are simple and inexpensive to make.
A9. Slip.
A10. Load.
A11. Single-phase induction motor.
A12. By using combinations of inductance and capacitance to apply out-of phase currents in starting windings.
A13. They have very weak starting torques.
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AMPLIDYNE—A special dc generator in which a small dc voltage applied to field windings controls a large output voltage from the generator. In effect, an amplidyne is a rotary amplifier, oftentimes producing gain in the order of 10,000.
ARMATURE—The windings in which the output voltage is generated in a generator or in which input current creates a magnetic field that interacts with the main field in a motor. Note: Armature is often used as being identical with ROTOR. This usage is correct only part of the time. See the text and the entries under ROTOR and STATOR in this Glossary.
ARMATURE LOSSES—Copper losses, eddy current losses, hysteresis losses which act to decrease the efficiency of armatures.
ARMATURE REACTION—The effect, in a dc generator, of current in the annature creating a magnetic field that distorts the main field and causing a shift in the neutral plane.
BRUSHES—Sliding contacts, usually carbon, that make electrical connection to the rotating part of a motor or generator.
COMMUTATION—The act of a commutator in converting generator output from an ac voltage to a dc voltage.
COMMUTATOR—A mechanical device that reverses armature connections in motors and generators at the proper instant so that current continues to flow in only one direction. In effect, the commutator changes ac to dc.
COMPENSATING WINDINGS—Windings embedded in slots in pole pieces, connected in series with the armature, whose magnetic field opposes the armature field and cancels armature reaction.
COMPOUND-WOUND MOTORS AND GENERATORS—Machines that have a series field in addition to a shunt field. Such machines have characteristics of both series- and shunt-wound machines.
CAPACITOR-START MOTOR—A type of single-phase, ac induction motor in which a starting winding and a capacitor are placed in series to start the motor. The values of Xc and R are such that the main-winding and starting-winding currents are nearly 90 degrees apart, and starting torque is produced as in a two-phase motor.
COUNTER EMF—The voltage generated within a coil by a moving magnetic field cutting across the coil itself. This voltage is in opposition (counter) to the moving field that created it. Counter emf is present in every motor, generator, transformer, or other inductance winding, whenever an alternating current flows.
DELTA—A 3-phase connection in which windings are connected end-to-end, forming a closed loop that resembles the Greek letter Delta. A separate phase wire is then connected to each of the three junctions.
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DRUM-TYPE ARMATURE—An efficient, popular type of armature designed so that the entire length of the winding is cutting the field at all times. Most wound armatures are of this type.
EDDY CURRENTS—Currents induced in the body of a conducting mass by a variation in magnetic flux.
FIELD—The electromagnet that furnishes the magnetic field that interacts with the armature in motors and generators.
FIELD EXCITATION—The creation of a steady magnetic field within the field windings by applying a dc voltage either from the generator itself or from an external source.
GENERATOR—A machine that converts mechanical energy to electrical energy by applying the principal of magnetic induction. A machine that produces ac or dc voltage, depending on the original design.
GRAMME-RING ARMATURE—An inefficient type of armature winding in which many of the turns are shielded from the field by its own iron ring.
INDUCTION MOTOR—A simple, rugged, ac motor with desirable characteristics. The rotor is energized by transformer action (induction) from the stator. More induction motors are used than any other type.
INTERPOLES—Small auxiliary poles placed between main field poles, whose magnetic field opposes the armature field and cancels armature reaction. Interpoles accomplish the same thing as compensating windings.
LAP WINDING—An armature winding in which opposite ends of each coil are connected to adjoining segments of the commutator so that the windings overlap.
LEFT-HAND RULE FOR GENERATORS—A representation of the relationships between motion, magnetic force, and resultant current in the generation of a voltage. The thumb, forefinger, and middle finger of the left hand are extended at right angles to each other. The thumb should point in the direction the conductor moves. The forefinger should point in the direction of magnetic flux from north to south. The middle finger will then point in the direction the generated voltage forces current to flow. Any of three quantities may be found if the other two are known.
MAGNETIC INDUCTION—The generation of a voltage in a circuit by causing relative motion between a magnetic field and the circuit. The relative motion can be the result of physical movement or the rise and fall of a magnetic field created by a changing current.
MOTOR—A machine that converts electrical energy to mechanical energy. It is activated by ac or dc voltage, depending on the design.
MOTOR LOAD—Any device driven by a motor. Typical loads are drills, saws, water pumps, rotating antennas, generators, etc. The speed and power capabilities of a motor must be matched to the speed and power requirements of the motor load.
MOTOR REACTION—The force created by generator armature current that tends to oppose normal rotation of the armature.
MOTOR STARTERS—Large resistive devices placed in series with dc motor armatures to prevent the armature from drawing excessive current until armature speed develops counter emf. The resistance is gradually removed from the circuit either automatically or manually as motor speed increases.
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MULTIPHASE—See polyphase.
POLE PIECES—The shaped magnetic material upon which the stator windings of motors and generators are mounted or wound.
POLE—The sections of a field magnet where the flux lines are concentrated; also where they enter and leave the magnet.
POLYPHASE—Term that describes systems or units of a system that are activated by or which generate separate out-of-phase voltages. Typical polyphase systems are 2-phase and 3-phase whose voltages are 90- and 120-degrees out of phase, respectively. This term means the same as MULTIPHASE.
PRIME MOVER—The source of the turning force applied to the rotor of a generator. This may be an electric motor, a gasoline engine, steam turbine, etc.
ROTATING FIELD—The magnetic field in a multiphase ac motor that is the result of field windings being energized by out-of-phase voltages. In effect, the magnetic field is made to rotate electrically rather than mechanically.
ROTOR—The revolving part of a rotating electrical machine. The rotor may be either the field or the armature, depending on the design of the machine.
SELF-EXCITED GENERATORS—Dc generators in which the generator output is fed to the field to produce field excitation.
SERIES-WOUND MOTORS AND GENERATORS—Machines in which the armature and field windings are connected in series with each other.
SHUNT-WOUND MOTORS AND GENERATORS—Machines in which the armature and field windings are connected in parallel (shunt) with each other.
SLIP—The difference between rotor speed and synchronous speed in an ac induction motor. The rotor will always be slower than the synchronous speed by the amount of slip, otherwise, no voltage would be induced in the rotor.
SLIP RINGS—Contacts that are mounted on the shaft of a motor or generator to which the rotor windings are connected, and against which the brushes ride.
SQUIRREL-CAGE WINDINGS—A type of rotor winding in which heavy conductors are imbedded in the rotor body. The conductors are shorted together at the ends by continuous rings. No insulation is required between the windings and the core. This type of winding is rugged, easily manufactured, and practically maintenance free. It is widely applied in ac induction motors. Physically, it appears as a rotating squirrel-cage, thus the name.
STATOR—The stationary part of a rotating electrical machine. The stator may be either the field or the armature, depending on the design of the machine.
SYNCHRONOUS MOTOR—An ac motor whose rotor is activated by dc. It is characterized by constant speed and requires squirrel-cage windings or some other method to be self-starting.
SYNCHRONOUS SPEED—The speed at which the rotating field in an ac motor revolves. This speed is a function of the number of poles in the field and the frequency of the applied voltage.
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VOLTAGE REGULATION—A measure of the ability of a generator to maintain a constant output voltage from no-load to full-load operation. Expressed as a percentage of full-load voltage, the better the regulation, the lower the percent.
WAVE WINDING—An armature winding in which the two ends of each coil are connected to commutator segments separated by the distance between poles. The winding goes successively under each main pole before reaching the starting point again.
WYE (Y)—A 3-phase connection in which one end of each phase winding is connected to a common point. Each free end is connected to a separate phase wire. The diagram of this connection often resembles the letter Y.
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INDEX-2
INDEX-3
Information: The text pages that you are to study are provided at the beginning of the assignment questions.
1
ASSIGNMENT 1 Textbook assignment: “Introduction to Generators and Motors,” pages 1-1 through 4-18.
1-1. In generators, what principle is used to convert mechanical motion to electrical energy?
1. Atomic reaction 2. Electrical attraction 3. Magnetic repulsion 4. Magnetic induction
1-2. When you use the left-hand rule for generators, what is indicated by the middle finger?
1. Direction of flux 2. Direction of motion 3. Direction of current flow 4. Direction of the magnetic field
1-3. The output voltage of an elementary generator is coupled from the armature to the brushes by what devices?
1. Slip rings 2. Interpoles 3. Terminals 4. Pigtails
1-4. An elementary generator consists of a single coil rotating in a magnetic field. Why is NO voltage induced in the coil as it passes through the neutral plane?
1. Flux lines are too dense 2. Flux lines are not being cut 3. Flux lines are not present 4. Flux lines are being cut in the wrong
1-5. What components cause(s) a generator to produce a dc voltage instead of an ac voltage at its output?
1. The brushes 2. The armature 3. The slip rings 4. The commutator
1-6. When two adjacent segments of the commutator on a single-loop dc generator come in contact with the brush at the same time, which of the following conditions will occur?
1. The output voltage will be zero 2. The output voltage will be maximum
negative 3. The output voltage will be maximum
1-7. In an elementary, single-coil, dc generator with one pair of poles, what is the maximum number of pulsations produced in one revolution?
1. One 2. Two 3. Three 4. Four
1-8. If an elementary dc generator has a two- coil armature and four field poles, what is the total number of segments required in the commutator?
1. 8 2. 2 3. 16 4. 4
2
1-9. How can you vary the strength of the magnetic field in a dc generator?
1. By varying the armature current 2. By varying the speed of armature
rotation 3. By varying the voltage applied to the
electromagnetic field coils 4. By varying the polarity of the field
1-10. Under which of the following conditions does sparking occur between the brushes and the commutator?
1. When operating under normal conditions
2. When there is improper commutation 3. When there is an excessive load
current 4. When commutation is in the neutral
1-11. Distortion of the main field by interaction with the armature field defines what term?
1. Commutation 2. Mutual reaction 3. Armature reaction 4. Mutual induction
1-12. Distortion of the main field by interaction with the armature field can be compensated for by the use of
1. slip rings 2. interpoles 3. a commutator 4. special brushes
1-13. Motor reaction in a dc generator is a physical force caused by the magnetic interaction between the armature and the field. What effect, if any, does this force have on the operation of the generator?
1. It tends to oppose the rotation of the armature
2. It tends to aid the rotation of the armature
3. It causes the generator to vibrate 4. None
1-14. In dc generators, copper losses are caused by which of the following factors?
1. Reluctance in the field poles 2. Resistance in the armature winding 3. Reactance in the armature and field
windings 4. All of the above
1-15. Eddy currents in armature cores are kept low by which of the following actions?
1. Using powdered iron as a core material
2. Limiting armature current 3. Insulating the core 4. Laminating the iron in the core
1-16. What makes the drum-type armature more efficient than the Gramme-ring armature?
1. The drum-type armature has more windings than the Gramme-ring armature
2. The drum-type armature can be rotated faster than the Gramme-ring armature
3. The drum-type armature coils are fully exposed to the magnetic field, while the Gramme-ring armature coils are only partially exposed to the magnetic field
4. The drum-type armature has a laminated core, while the Gramme- ring armature has a solid core
3
1-17. What type of dc generator application best utilizes the features of the lap- wound armature?
1. High-voltage 2. High-current 3. High-speed 4. Variable-speed
1-18. Which of the following is NOT a major classification of dc generators?
1. Compound-wound 2. Series-wound 3. Shunt-wound 4. Lap-wound
1-19. What characteristic of series-wound generators makes them unsuitable for most applications?
1. They require external field excitation 2. The output voltage varies as the
speed varies 3. They are not capable of supplying
heavy loads 4. The output voltage varies as the load
1-20. As the load current of a dc generator varies from no-load to full-load, the variation in output voltage is expressed as a percent of the full-load voltage. What term applies to this expression?
1. Gain 2. Voltage control 3. Voltage regulation 4. Load limit
1-21. When two or more generators are used to supply a common load, what term is applied to this method of operation?
1. Series 2. Compound 3. Split-load 4. Parallel
1-22. What special-purpose dc generator is used as a high-gain power amplifier?
1. Lap-wound 2. Shunt-wound 3. Amplidyne 4. Compound-connected
1-23. The gain of an amplifying device can be determined by which of the following formulas?
1. GAIN = INPUT + OUTPUT 2. GAIN = INPUT · OUTPUT 3. GAIN = OUTPUT - INPUT 4. GAIN = OUTPUT + INPUT
1-24. The maximum gain possible from an amplidyne is approximately
1. 100 2. 5,000 3. 10,000 4. 50,000
1-25. What determines the direction of rotation of a dc motor?
1. The type of armature 2. The method of excitation 3. The number of armature coils 4. The polarity of armature current and
1-26. When you use the right-hand rule for motors, what quantity is indicated by the extended forefinger?
1. Direction of flux north to south 2. Direction of flux south to north 3. Direction of current 4. Direction of motion
4
1-27. Which, if any, of the following situations is a major electrical difference between a dc motor and a dc generator?
1. The armatures are different 2. The shunt connections are different 3. The dc generator requires a
commutator, the dc motor does not 4. None of the above
1-28. In a dc motor, what causes counter emf?
1. Improper commutation 2. Armature reaction 3. Generator action 4. Excessive speed
1-29. In a dc motor, how, if at all, does counter emf affect speed?
1. It causes the speed to increase 2. It causes the speed to decrease 3. It causes rapid fluctuations of the
speed 4. It does not affect speed
1-30. What is the load on a dc motor?
1. The field current 2. The armature current 3. The mechanical device the motor
moves 4. The total current drawn from the
1-31. When a series dc motor is operated without a load, which of the following conditions occurs?
1. The armature draws excessive current
2. The voltage requirement increases 3. The armature will not turn 4. The armature speeds out of control
1-32. A dc series motor is best suited for which of the following applications?
1. Steady load, low torque 2. Variable load, low torque 3. Steady load, high torque 4. Variable load, high torque
1-33. What is the main advantage of a shunt motor over a series motor?
1. A shunt motor develops higher torque at lower speeds than a series motor
2. A shunt motor can be operated at higher speeds than a series motor
3. A shunt motor draws less current from the source than a series motor
4. A shunt motor maintains a more constant speed under varying load conditions than a series motor
1-34. How can the direction of rotation be changed in a dc motor?
1. Only by reversing the field connections
2. Only by reversing the armature connections
3. By reversing both the armature connections and the field connections
4. 4.By reversing either the armature connections or the field connections
1-35. When the voltage applied to the armature of a dc shunt motor is decreased, what happens to the motor speed?
1. It becomes uncontrollable 2. It decreases 3. It increases 4. The motor stops
1-36. In a dc motor, the neutral plane shifts in what direction as the result of armature reaction?
1. Clockwise 2. Counterclockwise 3. In the direction of rotation 4. Opposite the direction of rotation
5
1-37. The current in the interpoles of a dc motor is the same as the
1. armature current 2. field current 3. total load current 4. eddy current
1-38. In a dc motor, what is the purpose of the resistor placed in series with the armature?
1. To counteract armature reaction 2. To limit armature current 3. To increase field strength 4. To prevent overspeeding
1-39. Magnetic induction in an alternator is a result of relative motion between what two elements?
1. The rotor and the armature 2. The armature and the field 3. The field and the stator 4. The rotor and the field
1-40. Voltage is induced in what part of an alternator?
1. The commutator 2. The brushes 3. The armature 4. The field
1-41. What are the two basic types of alternators?
1. Multiphase and polyphase 2. Alternating current and direct current 3. Rotating field and rotating armature 4. Series-wound and shunt-wound
1-42. Which of the following alternator types is most widely used?
1. Shunt-wound 2. Rotating-armature 3. Series-wound 4. Rotating-field
1-43. The purpose of the exciter in an alternator is to
1. provide dc field excitation 2. compensate for armature losses 3. compensate for counter emf 4. counteract armature reaction
1-44. An alternator using a gas turbine as a prime mover should have what type of rotor?
1. Turbine-driven 2. Salient-pole 3. Armature 4. Geared
1-45. In alternators with low-speed prime movers, only what type of rotor may be used?
1. Geared 2. Armature 3. Salient-pole 4. Turbine-driven
1-46. Alternators are rated using which of the following terms?
1. Volts 2. Watts 3. Amperes 4. Volt-amperes
1-47. What does the term single-phase mean relative to single-phase alternators?
1. All output voltages are in phase with each other
2. The voltage and current are in phase 3. The phase angle is constant 4. Only one voltage is produced
1-48. In a single-phase alternator with multiple armature windings, how must the windings be connected?
1. Series 2. Parallel 3. Wye 4. Delta
6
IN ANSWERING QUESTION 1-49, REFER TO FIGURE 1A.
1-49. What is the phase relationship between voltages A and B?
1. In phase 2. 45º out of phase 3. 90º out of phase 4. 180º out of phase
1-50. A two-phase, three-wire alternator has what maximum number of output voltages available?
1. One 2. Two 3. Three 4. Four
THIS SPACE LEFT BLANK INTENTIONALLY.
IN ANSWERING QUESTION 1-51, REFER TO FIGURE 1B.
1-51. What is the relative amplitude of the voltage at output C as compared to A and B?
1. C is .707 times A or B 2. C is equal to the difference between
and B 3. C is 1.414 times A or B 4. C is twice the sum of A and B
1-52. What determines the phase relationship between the individual output voltages in a multiphase alternator?
1. The speed of rotation 2. The number of field poles 3. The method of connecting the
terminals 4. The placement of the armature coils
1-53. What is the phase relationship between the output voltages of a three-phase alternator?
1. In phase 2. 60º out of phase 3. 90º out of phase 4. 120º out of phase
7
1-54. The ac power aboard ship is usually distributed as what voltage?
1. 115-volt, three-phase 2. 115-volt, single-phase 3. 230-volt, single-phase 4. 450-volt, three-phase
1-55. The output frequency of an alternator is determined by what two factors?
1. The number of poles and the number of phases
2. The number of poles and the speed of rotation
3. The speed of rotation and the volt- ampere rating
4. The number of phases and the volt- ampere rating
1-56. A four-pole, single-phase alternator rotating at 18M rpm will produce what output frequency?
1. 60 Hz 2. 400 Hz 3. 1800 Hz 4. 3600 Hz
1-57. Which of the following is the correct formula for determining the percent of regulation of an alternator?
1.
2.
3.
4.
1-58. In most alternators, the output voltage is controlled by adjusting the
1. rotor speed 2. field voltage 3. armature resistance 4. electric load
1-59. When alternators are to be operated in parallel, which of the following alternator characteristics must be considered?
1. Voltage 2. Frequency 3. Phase relationship 4. All the above
1-60. Which of the following motors is/are types of ac motor?
1. Series 2. Synchronous 3. Induction 4. All of the above
1-61. Which of the following types of motors is widely used to power small appliances?
1. Universal 2. Synchronous 3. Polyphase 4. Compound
1-62. A universal motor is a special type of
1. synchronous motor 2. series motor 3. parallel motor 4. polyphase motor
1-63. The number of pole pairs required to establish a rotating magnetic field in a multiphase motor stator is determined by which of the following factors?
1. The magnitude of the voltage 2. The magnitude of the current 3. The number of phases 4. The size of the motor
8
1-64. In a two-phase motor stator, what is the angular displacement between the field poles?
1. 0º 2. 90º 3. 180º 4. 360º
1-65. Adjacent phase windings of a 3-phase motor stator are what total number of degrees apart?
1. 30º 2. 90º 3. 120º 4. 180º
1-66. Which of the following types of motors has a constant speed from no load to full load?
1. Series 2. Synchronous 3. Induction 4. Universal
1-67. What type of ac motor is the simplest and least expensive to manufacture?
1. Induction 2. Series 3. Synchronous 4. Two-phase
1-68. What term applies to the difference between the speed of the rotating stator field and the rotor speed?
1. Slip 2. Synchronous 3. Rotor error 4. Torque
1-69. The speed of the rotor of an induction motor depends upon which of the following factors?
1. The method of connecting the load 2. The dc voltage applied to the rotor 3. The torque requirements of the load 4. The current in the rotor
1-70. What type of ac motor is most widely used?
1. Series 2. Universal 3. Synchronous 4. Single-phase induction
1-71. What type of ac motor uses a combination of inductance and capacitance to apply out-of-phase currents to the start windings?
1. Three-phase 2. Series 3. Synchronous 4. Split-phase induction
1-72. Why are shaded-pole motors built only in small sizes?
1. They have weak starting torque 2. They are expensive in large sizes 3. They are unidirectional 4. They require large starting current


Chocolate Pizza
POSTED ON 15 DEC 2013/DESSERTS
For the fig-swirl: Melt butter over medium heat in a saucespan. Add brown sugar and stir to disolve. Halve all of the figs and toss in the saucepan with water and lemon juice. Cook over medium heat, stiring frequently, until you have a chunky-jammy mixture. Add salt with one or two stirs, set aside and let cool completely.
Ice cream: In a small pot over medium heat, combine milk, and granulated sugar until sugar is completely disolved and the milk is just barely lukewarm. Whisk in the egg yoks. Set mixture in the fridge and wait until the fig mixture is cooled.
Using an ice cream machine, pour liquids into the frozen basin and process according to manufacturer instructions, i.e., let spin and thicken for 20 minutes before adding mascarpone, fig jam mixture, and the nuts. Continue to process for +/- 10 minutes. Pour semi-frozen mixture into a pyrex dish or glass tupperware. Freeze for at least two hours before serving.
- 1 1/2 cups milk
- 1/2 cup mascarpone
- 1/2 tsp pink salt
- 1 lb Black Mission Figs
- 1/2 cup brown sugar
- 2-4 tbsp water


Changes are split into three categories:
- Major changes: The major new features that all users should know about.
- Minor changes: Any smaller changes, including bug fixes.
- API changes: Any changes to the API that could impact existing users.
Version 1.0
Major changes
- Use JDK 5 language features.
- Added builder classes for all toys (refer Martin Fowler's FluentInterface).
- New FutureToy to run methods asynchronously (JIRA:PTOYS-5).
- New PrivilegeToy to run methods as privileged actions.
- Maven groupId changes from "proxytoys" to "com.thoughtworks.proxytoys".
This release is source and binary incompatible with any previous version to allow maximum support of Java 5 features in the API.
Version 0.2
Major changes
- Added Pool proxy (JIRA:PTOYS-4).
- Added Dispatcher proxy (JIRA:PTOYS-9).
- Compatibility for CGLIB 2.0.2 (JIRA:PTOYS-7) and CGLIB 2.1.
- Classes compiled for JDK 1.3.
- Multicaster proxies implement now Multicast.
- A lot of Javadoc and package overviews with examples.
- Removed Future object (JIRA:PTOYS-2)
- Ensure proxies can be serialized by JDK and XStream even with JDK 1.3.
Minor changes
- Fix equality for delegated objects (JIRA:PTOYS-3).
- Fix recursion problem for delegating objects (JIRA:PTOYS-8).
- Decorates can now call the protected methods of its delegate.
- Echo objects use now the given ProxyFactory.
- Echo objects will now also trace return values and thrown exceptions.
- Fixed a lot of concurrency issues.
- Multicaster will no longer try and fail to proxy final classes.
- Multicaster handles now all primitive types.
- Hot swapping proxy could not handle concrete classes (fix by Aaron Knauf).
- Fixed implicit and unnecessary references of the proxy instance to the ProxyFactory.
- Delegating proxies cache the matching methods internally.
API changes
- Copied ClassHierarchyInspector to ReflectionUtils in new package com.thoughtworks.proxy.kit and deprecated ClassHierarchyInspector.
- Methods of ReflectionUtils use now Set instances instead of Class arrays.
- Moved ObjectReference and SimpleReference into new package com.thoughtworks.proxy.kit.
- SimpleInvoker into new package com.thoughtworks.proxy.kit.
- InvocationDecorator methods now all receive at any time the proxy, the called method and the arguments.
- DelegatingInvoker no longer has public constants, use always Delegating.MODE_XXX constants
- The delegation mode is no longer set by a boolean (STATIC_TYPE or DYNAMIC_TYPE), but an integer value now (MODE_XXX).
- DelegatingInvoker no longer has public constants, use always Delegating.MODE_XXX constants
Version 0.1
Initial release.


The Brownie Law
The Brownie Law is a visual novel where you, as a Brownie Scout, must make some new friends and bring them back with you to the cult – I mean, club!
There are 3 girls you think would be well suited to join the Brownie Scouts, but to gain their trust you must first talk to them… And befriend them. No matter what it takes.
Talk to people and convince them to join the club, and remember, never take no for an answer. It’s all for a good cause, and I swear on this by the Brownie Law!
And no one ever breaks the Brownie Law…
For more information and to download, visit the game page on itch.io!


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This dialog appears when you invoke the File/New command. It allows you to create a file of any size filled with various values, which can then be edited as normal.
You can create very large files, but they may take some time to generate. The filesystem may limit file sizes (eg FAT has a limit of 4 GBytes). Also for large files HexEdit Pro may need to create a temporary disk file, but if the "Prompt for disk name now" option is used the data is written to directly to the final destination file to save copying later.
Size
Several options are available for specifying the initial file size. If the size to be used is greater than the length of the data the bytes of the data are repeated up to the desired length. Files up to 1 Terabyte in length can be created.
Data
The file size is taken from the length of the selected data (see Fill With options below) -- for example, the length of the entered string or the length of the data on the clipboard -- and multiplied by the "by:" factor to the right.
by:
The file length is the length of the data multiplied by this factor. The actual size is displayed to the right, after the equals sign (=).
Take Size from Calculator
The size of the new file is the value currently shown in the calculator. If the value is negative or zero an empty file is created. This option can be useful in keystroke macros.
Specified
The size is specified explicitly as either hex or decimal.
Decimal:
Enter the size of the new file you want in decimal.
Hex:
Enter the size you want in hex.
Prompt for Disk File Name
If you select this option the file is immediately created on disk. After you click OK you are prompted for a disk file name. This can save time later when the file is eventually saved if the file is very large.
Fill With
Choose how the values used to fill the new file are created by selecting from the radio buttons described below. The bytes are repeated until a file of the size specified is created.
Hex
Enter one or more byte values in hex. To make a file just containing null bytes simply use "00".
String
Enter one or more characters. The values are taken from the character set specified below.
Char Set
The character set used to generate byte values from the string. You can create ASCII, EBCDIC or Unicode data.
Clipboard
The data is taken from the clipboard (binary data or text if no binary data is available). A preview of the data on the clipboard is shown (as hex for binary data or as a string for text). If no valid formats are on the clipboard this option is disabled.
Length
Displays the number of bytes currently on the clipboard.
Random
Generates random byte values. You can enter one or more ranges. For example, use "65-90, 97-122" to generate random uppercase and lowercase ASCII letters. Use the range "0-255" to generate all possible byte values. The PRNG algorithm is seeded by the Random Seed command or the Seed Random Number Generator from Calculator command.
Note that you can use this to generate random integers too (of any size). However, you cannot use it to generate random floating point values - for one, you will generate some invalid floating point values (NaNs) - see Floating Point Numbers for more information. (A facility to generate random floating point number may be added in the future.)
The algorithm used quickly generates adequate random numbers. For a high quality PRNG use the "Operations/Random Fill/Generate Good" menu item.
Number
Enter a number that is used to fill the file up to the size entered (above). To use IEEE floating point numbers enter a number with a decimal point (such as "1.0") and/or an exponent (such as "-1e30").
Type
The type of integer or floating point number. You can use 1, 2, 4 or 8 byte integers, or 4 or 8 byte IEEE floating point numbers.
Big-endian
Determines the byte order of the number entered. (See the information on byte order in Numeric Operations.)


Writing
Deploy a Node.js app in minutes using Heroku!
As more and more Node.js projects are being coded, deploying a nodejs app just got easier. I would guide you through on how one can deploy a node.js app in minutes using Heroku.
What is Heroku?
Heroku is a cloud platform that lets companies/individuals build, deliver, monitor, and scale applications. It is often regarded as the fastest way to go from an idea to URL bypassing all those infrastructure headaches (i.e, one doesn’t has to worry about infrastructure; just focus on the application).
What Heroku offers?
Heroku offers Platform as a Service [PaaS] type of cloud computing, the delivery of computing services : servers, storage, databases, networking, software, and more over the Internet (“the cloud”).
Operating at the layer above raw computing hardware, whether physical or virtual, Platform as a Service [PaaS] provides a method for programming languages to interact with services like databases, web servers, and file storage, without having to deal with lower level requirements like how much space a database needs, whether the data must be protected by making a copy between 3 servers, or distributing the workload across servers that can be spread throughout the world. Typically, applications must be written for a specific PaaS offering to take full advantage of the service, and most platforms only support a limited set of programming languages.
Advantages/Benefits
There is no doubt that Heroku takes away all the pain of installing softwares, configuring servers, maintaining, and monitoring the software — it takes care of most of the configurations. Other services could easily be added as add-ons.
Heroku is:
- Easy deployment
- Uses version control system commands (git)
- Security
- Plenty of Add-on resources (applications, databases etc.)
- Processes scaling : independent scaling for each component of your app without affecting functionality and performance
- Isolation : each process (i.e dyno) is completely isolated from each other thorough Documentation
How to deploy a Node.js app :
Here are some prerequisites you need to have before deploying :
- A Node.js app. [ofcourse xD]
- A free Heroku account.
- The Heroku CLI.
Let’s get down to it!
-
Login to your Heroku via the command line heroku login. This will prompt for your credential. Add Procfile to your application echo
‘web: ./node_modules/.bin/forever -m 5 server.js’ >Procfile
A Procfile is not necessary to deploy apps written in most languages supported by Heroku. The platform automatically detects the language, and creates a default web process type to boot the application server. In the case of Node.js, it will start a default web process via the start script in yourpackage.json
. Creating an explicit Procfile is recommended for greater control and flexibility for your app.As the case maybe,web: ./node_modules/.bin/forever -m 5 server.js
, I am using Node.js’ forever module to start my server named server.js -
Create Heroku remote repository
heroku create appName
-
Add the new changes made to the app
git add .

-
Push to your app to the newly created heroku remote repository
git push heroku master
Bonus: run heroku logs
to see logs.
Note: If your app runs on a database, you will need to add the database as an add-on.
Feel free to ping me on Twitter.


Application
Servers
Application
Refresh
Create
Application
Back
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Download Template
Application ID
Application Name
Auto Start
App Resources
{{template "page-servers.html"}}


@(query: Option[String], results: Option[services.SearchResults]) @main("Search Code") {
@{ """ |// In the future this will contain a preview of the matching file at the relevant location |def placeholder(arg: SomeType) = { | val x = doSomethingFancy(arg.foo()) | val y = x.bar() | // Well, this is just dummy code | x + " " + y |} """.stripMargin }
Here is some more information about this code snippet, like language, date, developper etc...


This module contains the datastructures used for working with
Textgrids, IntervalTiers, and PointTiers, and the primary
functions used to operate over them.
A Textgrid() is a container for annotation tiers. Annotation tiers come in two varieties: IntervalTier and PointTier. With this library, a textgrid can be queried, be used to filter data points, cleaned, or algorithmically altered, etc.
A Textgrid() is a container for annotation tiers. Annotation tiers come in two varieties: IntervalTier and PointTier. With this library, a textgrid can be queried, be used to filter data points, cleaned, or algorithmically altered, etc.
- Since:
- March 25, 2015
- Source:
Classes
Methods
(inner) compareEntries(entryA, entryB) → {boolean}
Returns true if the two entries are the same, false otherwise
Parameters:
| Name | Type | Description |
|---|---|---|
entryA |
Array | |
entryB |
Array |
- Source:
Returns:
- Type
- boolean
(inner) compareTextgrids(tg1, tg2) → {boolean}
Returns true if the two textgrids are the same, false otherwise
Parameters:
| Name | Type | Description |
|---|---|---|
tg1 |
Textgrid | |
tg2 |
Textgrid |
- Source:
Returns:
- Type
- boolean
(inner) compareTiers(tier1, tier2) → {boolean}
Returns true if the two tiers are the same, false otherwise
Parameters:
| Name | Type | Description |
|---|---|---|
tier1 |
TextgridTier | |
tier2 |
TextgridTier |
- Source:
Returns:
- Type
- boolean
(inner) copyTextgrid(tg) → {Textgrid}
Returns a deep copy of a textgrid.
Parameters:
| Name | Type | Description |
|---|---|---|
tg |
Textgrid |
- Source:
Returns:
- Type
- Textgrid
(inner) copyTier(tier) → {TextgridTier}
Returns a deep copy of a tier
Parameters:
| Name | Type | Description |
|---|---|---|
tier |
TextgridTier | |
|
Object | an object containing optional values to replace those in the copy. If the four paramaters name, entryList, minTimestamp, and maxTimestamp are null or not specified, those in the tier will be used (default behaviour). |
- Source:
Returns:
- Type
- TextgridTier
(inner) findLabelInTier() → {Array}
Returns the indexes of the entries that match the search label
- Source:
Returns:
- Type
- Array
(inner) getEntriesInInterval() → {Array}
Given an interval, returns entries in an interval tier that are in or (for intervals) that partially overlap with it
- Source:
Returns:
entryList
- Type
- Array
(inner) getNonEntriesFromIntervalTier() → {Array}
Returns the regions of the textgrid without labels
- Source:
Returns:
invertedEntryList - where each entry looks like [start time, end time, '']
- Type
- Array
(inner) getValuesAtPoints(pointTier, dataTupleList) → {Array}
Get the values that occur at points in the point tier.
Parameters:
| Name | Type | Description |
|---|---|---|
pointTier |
PointTier | |
dataTupleList |
Array | should be ordered in time; must be of the form [(t1, v1a, v1b, ..), (t2, v2a, v2b, ..), ..] |
- Source:
Returns:
- Type
- Array
(inner) getValuesInIntervals() → {Array}
Returns data from dataTupleList contained in labeled intervals
- Source:
Returns:
- Type
- Array


This example demonstrates how to autocomplete works with an ActivationChar option, press "*" in any value and continue with autocompletion. The autocomplete returns the posible jsonpaths of the existing json document, for example *object.a.
*object.a


Workflow Management
Last updated on Thursday 1 May 2090 at 11:56pm
| Available | 95 |
| Unavailable | 73 |
| volumeume change of ownership | 60 |
| volume register update | 40 |
| Actionable Deferral requisition | 5 |
| volume change of ownership | 325 |
| volume register update | 333 |
| Actionable Deferral requisition | 114 |
| Available | 133 |
|---|---|
| volume change of ownership | 50 |
| volume register update | 50 |
| Actionable Deferral requisition | 33 |
| Unavailable | 105 |
| volume change of ownership | 60 |
| volume register update | 40 |
| Actionable Deferral requisition | 5 |
| Deferred | 5 |
| volume change of ownership | 95 |
| volume register update | 73 |
| Actionable Deferral requisition | 104 |
| volume change of ownership | 95 |
| volume register update | 73 |
| Actionable Deferral requisition | 104 |


Jul 2017
Prague was like time traveling. To all the good parts.
The streets of Old Town Prague are filled with souvenir stores and cute handicrafts. Every store I walked into had a different nostalgic tone. Some felt like a mini cottage house and others like your grandfather just unearthed his collection of old and delicate wooden handmade toys from the attic. Whatever it is, it just felt so heartwarming.
At this one particular toy store, I immersed myself and completely lost track of time. Rather, I went back in time to the old childhood days. There were rows and rows of wooden toys on the shelves, hanging over my head and against the wall. The entire space was enwrapped with toys that it felt like a safe space.
It's one of those places where you think to yourself "I'm gonna buy these for my kids". Just for a moment, I forgot about all the Nintendos and iPads our generation grew up with, and just appreciated these old school toys.
It was so good to remember that the little things are enough to make us feel happy and grateful. Because sometimes, we just forget.


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ObjectUtils
- Class in
PlayerWarpGUI.Utils.Warp
Holds methods related to Warp Object processing.
ObjectUtils()
- Constructor for class PlayerWarpGUI.Utils.Warp.
ObjectUtils
onCommand(CommandSender, Command, String, String[])
- Method in class PlayerWarpGUI.Commands.SubCommands.
BanCommand
onCommand(CommandSender, Command, String, String[])
- Method in class PlayerWarpGUI.Commands.SubCommands.
DeleteWarpCommand
onCommand(CommandSender, Command, String, String[])
- Method in class PlayerWarpGUI.Commands.SubCommands.
HelpCommand
onCommand(CommandSender, Command, String, String[])
- Method in class PlayerWarpGUI.Commands.SubCommands.
ListCommand
onCommand(CommandSender, Command, String, String[])
- Method in class PlayerWarpGUI.Commands.SubCommands.
SetIconCommand
onCommand(CommandSender, Command, String, String[])
- Method in class PlayerWarpGUI.Commands.SubCommands.
SetLoreCommand
onCommand(CommandSender, Command, String, String[])
- Method in class PlayerWarpGUI.Commands.SubCommands.
SetTitleCommand
onCommand(CommandSender, Command, String, String[])
- Method in class PlayerWarpGUI.Commands.SubCommands.
SetWarpCommand
onCommand(CommandSender, Command, String, String[])
- Method in class PlayerWarpGUI.Commands.SubCommands.
ShowCommand
onCommand(CommandSender, Command, String, String[])
- Method in class PlayerWarpGUI.Commands.SubCommands.
UnbanCommand
onEnable()
- Method in class PlayerWarpGUI.
PlayerWarpGUI
onPlayerMove(PlayerMoveEvent)
- Method in class PlayerWarpGUI.Listeners.
PlayerListener
Listener to Player move event.
Send teleport class when a player moves.
onWarpItemClick(InventoryClickEvent)
- Method in class PlayerWarpGUI.Listeners.
ChestListener
When a item in a inventoryChest is clicked.
openGUI(Player, int)
- Method in class PlayerWarpGUI.Objects.
GUIObject
Creates and show the inventory populated with warps to the Player.
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A full stack developer is a web developer or engineer who works with both the front and back ends of a website or application—meaning they can tackle projects that involve databases, building user-facing websites, or even work with clients during the planning phase of projects.
The web designers are responsible for the visual aspect, which includes the layout, coloring and typography of a web page. Web designers will also have a working knowledge of markup languages such as HTML and CSS, although the extent of their knowledge will differ from one web designer to another.


Repeating what someone said is a technique that I've been taught before as a mechanism to make sure you're understanding someone fully. What is different about the Looping technique is that it is more thorough
Joolz was a champ! Her feedback: Repeating the conversation back expresses that your actively listening and trying to understand. Asked for more informations for confirmation around clarity of understanding which then lead to an offer of help.
I like the buddy system. I'm quite a fan of team work as it makes me more aware of being accountable and creates strong motivation to stay on track.
Even though I like to practice daily mindfulness we all have this awesome habit of not doing the things we enjoy that we know are good for us in favour of the things that are crappy and totally suck! Yay US! The one mindful breath a day is awesome. It makes me feel like, even when I'm stressed out or feeling like crap, that I've at least taken one moment out of the day for my for wellbeing. I like being a well being.
Practice makes perfect. BUT - perfection is the result of practicing - not the action of practicing. And, even though the action may be simple, it's so hard to get right. Still with me? It's all good - keep practicing.


Altoro Mutual has raised its prime rate to 5.25 percent from 5.00 percent, effective today. This follows a similar increase by the Federal Reserve Bank of 0.25 percent in its target for federal funds rate.
More Press Releases


About
I have worked hard to enter the technology industry and I'm not looking back. After learning a breadth of technical skills at a coding boot camp, I was soon hired as a software engineer in San Diego. Now I have nearly two years of experience building a variety of software and web applications. I do my best work when I get to collaborate with dynamic teams who are passionate about creating impactful products.
I've been living in San Diego for the last eight years and I am happy to call it my home. I love the beaches, warm weather, and local craft beer scene. When I'm not sitting behind a computer monitor, I enjoy trying new restaurants, listening to live music, and playing or watching soccer. If you'd like to talk about coding or anything else, please reach out!


This section allows provisioning of existing entities such as users, groups and filters. Provisioning is a process of assigning roles - within any particular application - to an entity. After selecting an entity to provision there are three ways to choose applications you'd like to work with. First is to search for an application using a type-ahead. Second is to go through an alphabetically sorted list. Third is to apply another entity as a template.
This section allows the creation of new entities: Groups and Filters. A group is a collection of users chosen from a type-ahead, list or based on another group as a template.
This section allows the management of created entities: Groups and Filters.


---
layout: post
title: Sound volume control from command line
date: '2008-03-02T23:16:00.003+01:00'
author: sax
tags:
- linux
- sound
modified_time: '2008-03-02T23:23:18.706+01:00'
blogger_id: tag:blogger.com,1999:blog-17453343.post-4913978457410202734
blogger_orig_url: http://saxuality.blogspot.com/2008/03/sound-volume-control-from-command-line.html
---
You need amixer
- just run it from the command line and it will list all elements you can set (PCM, mic, etc.) Than you can set volume for some element by issuing command: amixer set PCM 15


Freedom For The Übermensch!
Who should benefit from
Open Source Success?
Created by: Andy Choens<EMAIL_ADDRESS>Dafynitions
- Free and Open Source Software: FOSS
-
Übermensch: Developed by
the 19th century philosopher
Nietzsche. Translates as "over-man" or
"super-man".
- Four Freedoms: Stallman's
1986 definition of the Four Software
Freedoms. Not FDR's Four Freedoms speech from
1941.
How Do You Benefit From FOSS?
FOSS Tools Used By Audience
The Four Freedoms
-
Freedom 0: The freedom to
run the program for any purpose.
-
Freedom 1: The freedom to
study how the program works, and change it
to make it do what you wish.
-
Freedom 2: The freedom to
redistribute copies so you can help your
neighbor.
-
Freedom 3: The freedom to
improve the program, and release your
improvements (and modified versions in
general) to the public, so that the whole
community benefits.
Questions for the Übermensch:
- Question 1:
How are the needs of software developers different from end users?
- Question 2:
Does this mean software developers should have more freedom?
- Question 3:
What is the role of a freedom, if it is not used?
What is the source of Freedom / Morality?
According to Nietzsche:
- Morality does not inherently exist. (Nihilism)
- It is the responsibility / privilege of the Übermensch to define morality.
- How does a theoritical argument from the 19th century impact the digital world?
Geeky Übermensch?
-
Who knew Superman could look like this?

- We are end users too
-
Software Freedom, Today:
- Volkswagon's "cheat devices" -> smart cars
- Google EOL Revolov home-automation (May 15)
- Election Software
- Medical Devices
How Can We Continue The Revolution?


Preparation time
less than 30 mins
Cooking time
1 to 2 hours
Serves
Serves 6
Dietary
This fancy dessert uses dried garden lavender - try cooking it for your most discerning friends.
Equipment and preparation: for this recipe you will need 6 ramekins and a 30x20cm/12x8in baking tin.
Place six ramekins (7.5cm/3in wide and 4cm/1½in deep) in a deep-sided roasting tray. Preheat the oven to 150C/130C Fan/Gas 2.
Put 150g/5½oz of the caster sugar in a clean, heavy-based saucepan and heat over a high heat without stirring until the sugar melts and a golden-brown caramel forms. If you need to move the mixture to prevent it from burning, swirl the pan from time to time instead of stirring. (Caution: Melted sugar is very hot. Take care when cooking with it.)
Remove the pan from the heat and carefully add two tablespoons of recently boiled water to the caramel - it will spit and splutter a little, so keep your face at a safe distance from the pan. Swirl the pan until the sugar and water have combined to form a runnier caramel, then pour a little into the bottom of each ramekin, tipping them each this way and that until the caramel has evenly coated the base and sides. Set aside.
Heat the milk, cream and lavender in a separate saucepan over a low heat until just simmering.
Meanwhile, whisk the eggs and the remaining 75g/2¾oz sugar in a bowl until pale and fluffy.
Pour the hot milk mixture onto the egg mixture, whisking continuously until smooth. Strain the mixture into a jug through a fine sieve, then pour the strained mixture into the ramekins.
Add enough boiling water to the roasting tray to reach two-thirds of the way up the sides of the ramekins. Carefully transfer the roasting tray to the oven and bake the crème caramels for 40-45 minutes, or until just set. Remove from the oven and set aside in the roasting tray until cooled to room temperature.
When the ramekins are cool enough to handle, remove from the roasting tray and chill in the fridge for at least an hour.
For the shortbread, increase the oven temperature to 180C/160C Fan/Gas 4. Grease a 30x20cm/12x8in baking tin with butter.
Beat the butter and icing sugar in a bowl until light and fluffy, using an electric whisk. Fold in the lavender, cornflour and plain flour until the mixture comes together as a firm dough.
Press the dough into the prepared baking tin using your fingertips to form an even layer of dough about 1cm/½in thick. Prick the dough all over with a fork and sprinkle with the caster sugar, if using.
Bake the shortbread in the oven for 12-15 minutes, or until pale golden-brown and cooked through. Set aside to cool in the tin for a little while, then break into pieces.
To serve, remove the crème caramels from the ramekins by running a knife around the inside of each, then pressing the knife gently into one side of the crème caramels, and inverting the ramekins onto upturned serving plates. Serve with pieces of the shortbread alongside.


--- layout: base description: Template for a list of posts, with full width remarks: See also page.layout == 'archive' in footer.html ---


man
crank(1)
restart your processes, slowly
crankctl(1)
crank control client
crankx(1)
crank multi-control client


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Preparation time
less than 30 mins
Cooking time
10 to 30 mins
Serves
Serves 4
Dietary
For the short-bread crumble, mix all ingredients into a soft dough and knead lightly until smooth
Break off pieces of dough about the size of a walnut and flatten onto baking sheets
Bake at 170C/325F/Gas 3 for 12-15 minutes or until golden in colour
Cool slightly before breaking into rough pieces. Set aside
For the fruit base, melt the butter in a large frying pan.
Add the prepared rhubarb, sugar, cardamom, orange rind and the juice.
Cover and poach until the fruit softens.
Remove the rhubarb and reduce juices if you don t want the rhubarb to be soggy.
Remove pan from the heat and stir in orange flower water.
Transfer fruit to the individual ramekins or a pie dish.
Cover fruit with crushed biscuits and dust with icing sugar and serve immediately with hot custard.


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Colombian protests end with tear gas, curfew in city of Cali
by Carlos Vargas, Julia Symmes CobbBOGOTA (Reuters) - Colombian unions, student groups and other protesters marched on Thursday against rumored economic reform plans and amid rising discontent with the government of President Ivan Duque, while the city of Cali imposed a curfew from 7 p.m.
Hundreds of thousands took to the streets to demand the government maintain the minimum wage for young people and the universal right to a pension, even though Duque has repeatedly denied considering those changes.
Other groups of marchers protested what they say is a lack of government action to prevent the murder of hundreds of human rights activists, corruption at universities and other issues.
Duque has repeatedly said his government would not tolerate violence and police fired tear gas in several cities, including in Bogota’s storied Bolivar Plaza.
As of 7 p.m. (2400 GMT), 42 civilians and 37 police officers had been injured, the police and interior ministry said, while 36 people had been arrested. Some 207,000 people marched, they said, most heading home peacefully in the late afternoon.
“There has been a very positive citizen participation in practically the whole country,” Interior Minister Nancy Patricia Gutierrez told journalists. “There have been a series of isolated incidents that have been controlled appropriately and adequately by the national police.”
The Colombian protests coincide with demonstrations in other Latin American countries.
Chile’s conservative government is grappling with anti-austerity marches in the biggest crisis to hit that country since its return to democracy in 1990. In Bolivia, protests over vote tampering allegations led long-time leftist President Evo Morales to resign. His ouster has inflamed tensions in crisis-hit Nicaragua.
In Cali, where protesters blocked roads and vandalized mass transit buses, the mayor called a curfew from 7 p.m. until 6 a.m. (1100 GMT) Friday.
In Bogota, protesters also blocked roads and damaged 64 mass transit stations, authorities said. Police used tear gas in the northwestern neighborhood of Suba in an effort to break a blockade that closed a station early on Thursday morning.
In the evening, masked protesters burned several dumpsters and refused to allow a fire engine access to the blaze.
People across the city banged pots and pans in a sign of support for the protests.
“People from across the spectrum marched and I hope our president understands he has to grab the reins of the country and give us an assured path and hope for the young,” said 65-year-old pensioner and Duque voter Pablo Merchan. “He’s been in office for more than a year and hasn’t done anything.”
Police raids this week on activists and a culture magazine were widely criticized on social media. Cartel Urbano magazine staff posted videos showing police searching their offices.


PK2BM(1) PK2BM(1) NAME pk2bm - create a bitmap from a TeX pkfont SYNOPSIS: pk2bm [-bh] [-Wwidth] [-Hheight] -cchar pkfont pk2bm [-bh] [-Wwidth] [-Hheight] -ooctchar pkfont DESCRIPTION This program generates a bitmap (ASCII file) which can be used to create X11 applications. The bitmap file consists of all pixels of the specified character (via the -c or -o option) from the given pkfont. The format is described in bitmap(X11). The pkfont is a packed fontfile generated by gftopk(TeX) from a gffont. A gffont is the output of METAFONT a program to design fonts in a device independant way. With the -b flag a bitmap is generated in which all black pixels are drawn as a `*' and all white bits as a `.'. With the -h flag a hexadeci‐ mal bitmap dump is generated. The -W and/or -H options can be used to create a bitmap of respectivally `width' and `height' pixels. The pk-bitmap will in this case be centered according to these new dimensions. The output is written to the standard output. SEE ALSO `METAFONT', Donald Knuth. `The PKtype processor', belonging to the METAFONTware. bitmap(X11), gftopk(TeX), pktype(TeX), ps2pk(1) AUTHOR Piet Tutelaers<EMAIL_ADDRESS>TeX PK2BM(1)


| Documentation Contents |
jmap [ option ] pid jmap [ option ] executable core jmap [ option ] [server-id@]remote-hostname-or-IP
- option
- Options are mutually exclusive. Option, if used, should follow immediately after the command name.
- pid
- process id for which the memory map is to be printed. The process must be a Java process. To get a list of Java processes running on a machine, jps may be used.
- executable
- Java executable from which the core dump was produced.
- core
- core file for which the memory map is to be printed.
- remote-hostname-or-IP
- remote debug server's (see jsadebugd) hostname or IP address.
- server-id
- optional unique id, if multiple debug servers are running on the same remote host.
jmap prints shared object memory maps or heap memory details of a given process or core file or a remote debug server. If the given process is running on a 64-bit VM, you may need to specify the -J-d64 option, e.g.:
NOTE - This utility is unsupported and may or may not be available in future versions of the JDK. In Windows Systems where dbgeng.dll is not present, 'Debugging Tools for Windows' needs to be installed to have these tools working. Also, the PATH environment variable should contain the location of jvm.dll used by the target process or the location from which the Crash Dump file was produced.jmap -J-d64 -heap pidFor example, set PATH=<jdk>\jre\bin\client;%PATH%
- <no option>
- When no option is used jmap prints shared object mappings. For each shared object loaded in the target VM, start address, the size of the mapping, and the full path of the shared object file are printed. This is similar to the Solaris pmap utility.
- -dump:[live,]format=b,file=<filename>
- Dumps the Java heap in hprof binary format to filename. The live suboption is optional. If specified, only the live objects in the heap are dumped. To browse the heap dump, you can use jhat (Java Heap Analysis Tool) to read the generated file.
- -finalizerinfo
- Prints information on objects awaiting finalization.
- -heap
- Prints a heap summary. GC algorithm used, heap configuration and generation wise heap usage are printed.
- -histo[:live]
- Prints a histogram of the heap. For each Java class, number of objects, memory size in bytes, and fully qualified class names are printed. VM internal class names are printed with '*' prefix. If the live suboption is specified, only live objects are counted.
- -permstat
- Prints class loader wise statistics of permanent generation of Java heap. For each class loader, its name, liveness, address, parent class loader, and the number and size of classes it has loaded are printed. In addition, the number and size of interned Strings are printed.
- -F
- Force. Use with jmap -dump or jmap -histo option if the pid does not respond. The live suboption is not supported in this mode.
- -h
- Prints a help message.
- -help
- Prints a help message.
- -J<flag>
- Passes <flag> to the Java virtual machine on which jmap is run.
Copyright © 1993, 2011, Oracle and/or its affiliates. All rights reserved. Please send comments using this Feedback page. |
Java Technology |


A quick tutorial on how to make "Conway's Game of Life" using HTML, CSS, and Javascript
setupGrid()
when the webpage loadsid="table"
which will contain all of the rows of cellsgetIndex
which returns a cell's index given its row and columnsetupGrid
which will create the HTML elements to make our entire grid...but how?
Using nested for loops, each row is using the variable rowHTML
to create an entire row's HTML elements and adding it to the table's innerHTML.
Within each row, cells are being created as an HTML element with the class="cell"
to make them all styled as identical white squares and an id="cell" + index
so each cell has a specific index number inside its id.


LSEEK
Section: Linux Programmer's Manual (2)Updated: 2001-09-24
Index Return to Main Contents
NAME
lseek - reposition read/write file offsetSYNOPSIS
#include <sys/types.h>#include <unistd.h>
off_t lseek(int fd, off_t offset, int whence);
DESCRIPTION
The lseek() function repositions the offset of the open file associated with the file descriptor fd to the argument offset according to the directive whence as follows:- SEEK_SET
- The offset is set to offset bytes.
- SEEK_CUR
- The offset is set to its current location plus offset bytes.
- SEEK_END
- The offset is set to the size of the file plus offset bytes.
The lseek() function allows the file offset to be set beyond the end of the file (but this does not change the size of the file). If data is later written at this point, subsequent reads of the data in the gap (a "hole") return null bytes (aq\0aq) until data is actually written into the gap.
RETURN VALUE
Upon successful completion, lseek() returns the resulting offset location as measured in bytes from the beginning of the file. Otherwise, a value of (off_t) -1 is returned and errno is set to indicate the error.ERRORS
- EBADF
- fd is not an open file descriptor.
- EINVAL
- whence is not one of SEEK_SET, SEEK_CUR, SEEK_END; or the resulting file offset would be negative, or beyond the end of a seekable device.
- EOVERFLOW
- The resulting file offset cannot be represented in an off_t.
- ESPIPE
- fd is associated with a pipe, socket, or FIFO.
CONFORMING TO
SVr4, 4.3BSD, POSIX.1-2001.NOTES
This document's use of whence is incorrect English, but maintained for historical reasons.Some devices are incapable of seeking and POSIX does not specify which devices must support lseek().
On Linux, using lseek() on a tty device returns ESPIPE.
When converting old code, substitute values for whence with the following macros:
| old | new |
| 0 | SEEK_SET |
| 1 | SEEK_CUR |
| 2 | SEEK_END |
| L_SET | SEEK_SET |
| L_INCR | SEEK_CUR |
| L_XTND | SEEK_END |
SVr1-3 returns long instead of off_t, BSD returns int.
Note that file descriptors created by dup(2) or fork(2) share the current file position pointer, so seeking on such files may be subject to race conditions.
SEE ALSO
dup(2), fork(2), open(2), fseek(3), lseek64(3), posix_fallocate(3)COLOPHON
This page is part of release 3.22 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.
Index
This document was created by man2html, using the manual pages.
Time: 05:33:04 GMT, December 24, 2015


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Neural Episodic Control¶
Actions space: Discrete
References: Neural Episodic Control
Network Structure¶
Algorithm Description¶
Choosing an action¶
Use the current state as an input to the online network and extract the state embedding, which is the intermediate output from the middleware.
For each possible action \(a_i\), run the DND head using the state embedding and the selected action \(a_i\) as inputs. The DND is queried and returns the \(P\) nearest neighbor keys and values. The keys and values are used to calculate and return the action \(Q\) value from the network.
Pass all the \(Q\) values to the exploration policy and choose an action accordingly.
Store the state embeddings and actions taken during the current episode in a small buffer \(B\), in order to accumulate transitions until it is possible to calculate the total discounted returns over the entire episode.
Finalizing an episode¶
For each step in the episode, the state embeddings and the taken actions are stored in the buffer \(B\). When the episode is finished, the replay buffer calculates the \(N\)-step total return of each transition in the buffer, bootstrapped using the maximum \(Q\) value of the \(N\)-th transition. Those values are inserted along with the total return into the DND, and the buffer \(B\) is reset.
Training the network¶
Train the network only when the DND has enough entries for querying.
To train the network, the current states are used as the inputs and the \(N\)-step returns are used as the targets. The \(N\)-step return used takes into account \(N\) consecutive steps, and bootstraps the last value from the network if necessary: \(y_t=\sum_{j=0}^{N-1}\gamma^j r(s_{t+j},a_{t+j} ) +\gamma^N max_a Q(s_{t+N},a)\)
-
class
rl_coach.agents.nec_agent.
NECAlgorithmParameters
[source]¶ - Parameters
dnd_size – (int) Defines the number of transitions that will be stored in each one of the DNDs. Note that the total number of transitions that will be stored is dnd_size x num_actions.
l2_norm_added_delta – (float) A small value that will be added when calculating the weight of each of the DND entries. This follows the \(\delta\) patameter defined in the paper.
new_value_shift_coefficient – (float) In the case where a ew embedding that was added to the DND was already present, the value that will be stored in the DND is a mix between the existing value and the new value. The mix rate is defined by new_value_shift_coefficient.
number_of_knn – (int) The number of neighbors that will be retrieved for each DND query.
DND_key_error_threshold – (float) When the DND is queried for a specific embedding, this threshold will be used to determine if the embedding exists in the DND, since exact matches of embeddings are very rare.
propagate_updates_to_DND – (bool) If set to True, when the gradients of the network will be calculated, the gradients will also be backpropagated through the keys of the DND. The keys will then be updated as well, as if they were regular network weights.
n_step – (int) The bootstrap length that will be used when calculating the state values to store in the DND.
bootstrap_total_return_from_old_policy – (bool) If set to True, the bootstrap that will be used to calculate each state-action value, is the network value when the state was first seen, and not the latest, most up-to-date network value.


Getting Started
This page explains how to load and use MicroPython on the GHI Electronics supported devices.
The Terminal Software
Tera Term is the recommended terminal software but any other software should work. Tera Term is free and widely used. Download Tera Term from the downloads page or directly or search the web for downloads.
Unzip the downloaded file and run ttermpro.exe
. The software will look like the image below.
Go ahead and click cancel on this page.
The next step is to put the device in Loader
mode. This is accomplished by setting LDR pin low during reset or power up. On devices that have LDR button, just hold the LDR button down and continue to hold it down while reseting the board and then release the LDR button. This step will bring the device into loader mode, which will load a new virtual serial port. On windows, the Device Manager
will look something like the image below.
Go back to Tera Term and, from the top menu, select File->New connection...
. A new window will pop-up with serial ports updated with the COM port we have introduced in previous step. Select that new port and click OK.
Hit the enter key and the device should respond with Invalid Command.
Try to hit v
followed by enter and the device will respond with the boot loader versions number.
The device is now ready for the MicroPython firmware.
The MicroPyhon Firmware
Download the firmware from the Downloads page.
Tip
MicroPython is not available on all products.
Back to Tera Term, press U
followed by enter. The device will respond with Are you sure (Y/N)?
Now press 'Y' followed by enter.'
The device will now will be sending CCCCCCC.....
indicating that it is ready for the MicroPython file.
From top menu, File->Transfer->XMODEM->Send...
. This is an important, commonly missed step, you MUST select the 1K
checkbox!
Select the downloaded MicroPython file (glb file type) from earlier step. Progress window will show the update status. When upload has completed, reset the board.
If the firmware was loaded successfully, the PC will see a virtual memory driver, just like a USB memory drive. The drive will contain multiple files, one of them is main.py
, which is what MicroPyhton automatically runs on power up. The device will also bring up a vistual COM port, just like the one used in loader mode but this COM is for the REPL interface.
Activity LED
PA8 pin is a special pin that is used by the system to indicate status. For example, the pin goes high when saving to the internal storage. The Python script can safely use PA8 but anytime the system needs to indicate something it will override the pin and then release it back to the script.
REPL
Read Evaluate Print Loop is a very quick way to command and control a MicroPython-running device.
First find out the correct COM port and then start a new Tera Term connection to that port, just like we did with the boot loader. Once connected, the device will respond with something like:
MicroPython v1.15-21-g4dc8024-dirty on 2021-04-30; GHI Electronics SITCore v0.1.0 with SC13048
>>>
The device can now accept Python code! Try print(x)
and the device will respond with an error about x
. Now try x=10
and then print(x)
.
>>> x=10
>>> print(x)
10
>>>
This is example code to turn on activate an LED on pin PA8
from machine import Pin
led=Pin("PA8",Pin.OUT_PP)
led.high()
It is also possible to add a loop through REPL. Once a loop statement is entered (ending with :
) the REPL will automatically indent the following line.
To end the indentation and execute the block, press backspace or del, then enter.
>>> for i in range(10):
... print(i)
...
0
1
2
3
4
5
6
7
8
9
>>>
Tip
For a quick help on a any module, use the help function, like use help(machine)
.
main.py
This special file gets executed in power up. Open the file, from the device's virtual driver, and modify its content to a blink LED. Change the pin number to the LED on the device being used.
from machine import Pin
import time
led=Pin("PA8",Pin.OUT_PP)
while True
led.high();
time.sleep(0.5)
led.low();
time.sleep(0.5)
Save main.py
and wait for the activity LED/pin to go low, then reset the board. The led should be blinking. Use ctrl+C on the terminal to stop the program and go back to REPL.
Next Steps
Now that the device is running MicroPython, we can start learning about debugging tricks. And then the tutorials is a good next step.


Ok hereís my story. I didnít do the mushrooms for recreation this time, still I had lots of laughs :):):)
I have suffered from cluster headaches for 9 years now (9 years that I know of, the years before I did lsd or mushies at least once a year). I used to do a lot of drugs in the past, quit that way of life 10 years ago.
Then the headaches came, at first I was told they were dental problems, then jaw-problems, then neurological probs, migraine was also on the list, still no name for what I suffer from. Three years ago my doc told me that he suspected I was suffering from cluster headaches, all the symptoms matched. Since then I am looking for medication that gives me my life back. My cluster periods take up 9 months out of a year :(. I tried oxegen, used isoptine till last friday, had prednisolone (that helped for a while, but the side-effects are a problem for me), painkillers are no use for me.
What I found out for myself is that MDMA gives me 2 painfree days, I still enjoy going to the nice festivals they have here in Europe, 1 pill is good for a total painfree day (even alcohol doesnít cause an attack, but I donít do alcohol anymore, it is not worth the pain).
A while ago I read the flash posting on the internet, I got really curious about that, knowing MDMA gives me painfree time, the effect from the large doses of prednisolone......anybody who knows prednisolone knows. So I thought it was worth looking into the mushroom story.
I did mushrooms 6 years ago (recreationally), very strange, a long clusterfree-period after that (I checked all my doc appointments to be sure). Never realized that could be of the mushrooms, I just thought the wisdom teethvpain was gone.
Last week I could feel another CH-period was coming, so I went out to get mushrooms (very easy in the Netherlands). Stopped taking my isoptine on friday (just to be sure, my doc told me to) drank the tea on saturday, since than 1 attack on wed. Thatís it. I havenít used use medication for a week now, normally I would suffer big time by now.
It doesnít happen. I know when an attack occurs, but it is painfree!!! So now I am really looking for people who tried all of this......I have some questions, things only a clusterhead can understand.
I am going to be part of a dutch investigation regarding CH at the university of Leiden, I hope theyíll take this serious, don't really know of dutch CH's who tried mushroom tea.
I have been off medication for a week now, enjoying every day of the week so the psilocybin (actually psilocin is the miracle) must do something!!! year without cluster.....I would give a finger for that! The shroom is better :):):)
Experience Reports are the writings and opinions of the individual authors who submit them.
Some of the activities described are dangerous and/or illegal and none are recommended by Erowid.