Many people rely on google search for medical advice, information, educational purposes and more. Without Google search, it would be difficult to gather information or to find specific things with ease. With that being said, search engines like Google didn't always exist in the past. The web used to look like page after page of long lists of texts. This had made searching for specific things hard and wasted countless time for many. The roots of internet search was first found at Stanford by two individuals, Jerry Wang and David Filo. They started a company together called Yahoo, that revolutionized web search. The thought struck upon them when they were playing a fantasy basketball league and had access to the web. They crunched data to trade players etc. Yahoo changed the perspective that there was no money to be made on the web. Advertising was first brought up on Yahoo where the founders thought that ads would disrupt their business. It was quite the opposite, as the users doubled and continued to double.
Excite was another search startup competing against Yahoo. The company would basically crawl the web based upon a search term entered which was entirely different from Yahoo’s approach. Companies like Yahoo and Excite became portals for different things in the sake of advertising. However, despite all the innovations that were brough in, search wasn’t quite accurate yet. This is where Google came about to fix this main issue, with Sergey Brin and Larry Page taking the steed. Larry’s insight into search brought Google to where it is today. From his viewpoint, a page from one site to another can be thought of as a recommendation and thus link counting could be leveraged based upon the number of hits a site receives. These were the core model of Google’s success.
Despite Google’s advanced algorithm and search engine in place, a lot of companies and ventures didn’t think Google could make it. However, they missed out on a deal of a lifetime as Google exploded later. Google had no advertisements on their search engine at first. Later, they copied the design of advertising properly. The design was composed of figuring what types of products visitors would search for and purchase in the future. Keywords became very valuable for advertisers because of this and had become a money maker for Google. Overture’s website which had all of this embedded in its site, would be key for Google to have through monetization. Google had to copy Overture’s advertising algorithm after the deal with that company failed. Thus, Google Ad Words were born where blue colored sponsored web links were treated as advertisements. Google had ultimately changed the meaning of search in the past and its affects are still providing tremendous amounts of profits to this day.


C# test examples
In the following examples, the terminology component under test (abbreviated CUT) is used to mean the component that is the target of the test. The examples below use the Shouldly
assertion library as well. If you prefer not to use that just replace the assertions with the ones from your own favorite assertion library.
All examples can be found in the Tests folder in the Sample project.
Content:
- Testing components without parameters
- Testing components with parameters
2.1. Passing new parameters to an already rendered component - Testing components with child content
- Testing components with EventCallback parameters
- Testing components with cascading-value parameters
- Testing components that use on IJsRuntime
7.1 Verifying element references passed to InvokeAsync - Testing components with injected dependencies
- Dispatching @on-events from tests
Testing components without parameters
The following unit-tests verifies that the Counter.razor component behaves correctly. Here is the source for the Counter component:
@page "/counter"

Counter

Current count: @currentCount

<button class="btn btn-primary" @onclick="IncrementCount">Click me</button>
@code {
int currentCount = 0;
void IncrementCount()
{
currentCount++;
}
}
The CounterTest.cs looks like this:
public class CounterTest : ComponentTestFixture
{
[Fact]
public void InitialHtmlIsCorrect()
{
// Arrange - renders the Counter component
var cut = RenderComponent<Counter>();
// Assert
// Here we specify expected HTML from CUT.
var expectedHtml = @"
Counter

Current count: 0

<button class=""btn-primary btn"">Click me</button>";
// Here we use the HTML diffing library to assert that the rendered HTML
// from CUT is semantically the same as the expected HTML string above.
cut.MarkupMatches(expectedHtml);
}
[Fact]
public void ClickingButtonIncreasesCountStrict()
{
// Arrange - renders the Counter component
var cut = RenderComponent<Counter>();
// Act
// Use a Find to query the rendered DOM tree and find the button element
// and trigger the @onclick event handler by calling Click
cut.Find("button").Click();
// Assert
// GetChangesSinceFirstRender returns list of differences since the first render,
// in which we assert that there should only be one change, a text change where
// the new value is provided to the ShouldHaveSingleTextChange assert method.
cut.GetChangesSinceFirstRender().ShouldHaveSingleTextChange("Current count: 1");
// Repeat the above steps to ensure that counter works for multiple clicks
cut.Find("button").Click();
cut.GetChangesSinceFirstRender().ShouldHaveSingleTextChange("Current count: 2");
}
[Fact]
public void ClickingButtonIncreasesCountTargeted()
{
// Arrange - renders the Counter component
var cut = RenderComponent<Counter>();
// Act
// Use a Find to query the rendered DOM tree and find the button element
// and trigger the @onclick event handler by calling Click
cut.Find("button").Click();
// Assert
// Use a Find to query the rendered DOM tree and find the paragraph element
// and assert that its text content is the expected (calling Trim first to remove insignificant whitespace)
cut.Find("p").TextContent.Trim().ShouldBe("Current count: 1");
// Repeat the above steps to ensure that counter works for multiple clicks
cut.Find("button").Click();
cut.Find("p").TextContent.Trim().ShouldBe("Current count: 2");
}
}
A few things worth noting about the tests above:
InitialHtmlIsCorrect
uses theShouldBe
method that performs a semantic comparison of the generated HTML from CUT and the expected HTML string. That ensures that insignificant whitespace doesn't give false positives, among other things.The "strict" test (
ClickingButtonIncreasesCountStrict
) and the "targeted" test (ClickingButtonIncreasesCountTargeted
) takes two different approaches to verifying CUT renders the expected output:- The strict version generates a diff between the initial rendered HTML and the rendered HTML after the button click, and then asserts that the compare result only contains the expected change.
- The targeted version finds the

element expect to have changed, and asserts against its text content.
With the targeted version, we cannot guarantee that there are not other changes in other places of the rendered HTML, if that is a concern, use the strict style. If it is not, then the targeted style can lead to simpler test.
Testing components with parameters
In the following tests we will pass regular parameters to a component under test, e.g. [Parameter] public SomeType PropName { get; set; }
style properties, where SomeType
is not a RenderFragment
or a EventCallback
type.
The component under test will be the Aside.razor component, which looks like this:

@if (Header is { })
{
@Header
}
@ChildContent

@code {
[Parameter(CaptureUnmatchedValues = true)]
public IReadOnlyDictionary<string, object>? Attributes { get; set; }
[Parameter] public string? Header { get; set; }
[Parameter] public RenderFragment? ChildContent { get; set; }
}
The AsideTest.cs looks like this:
public class AsideTest : ComponentTestFixture
{
[Fact(DisplayName = "Aside should render header and additional parameters correctly")]
public void Test001()
{
// Arrange
var header = "Hello testers";
var cssClass = "some-class";
// Act - render the Aside component with two parameters (passed as pairs of name, value tuples).
// Note the use of the nameof operator to get the name of the Header parameter. This
// helps keeps the test passing if the name of the parameter is refactored.
//
// This is equivalent to the follow Razor code:
//
//
//
var cut = RenderComponent(
(nameof(Aside.Header), header),
("class", cssClass)
);
// Assert - verify that the rendered HTML from the Aside component matches the expected output.
cut.MarkupMatches($@"{header}");
}
}
In the test above, we use an overload of the RenderComponent<TComponent>()
method, that allow us to pass regular parameters as pairs of (string name, object? value)
.
As highlighted in the code, I recommend using the nameof
to get the name of declared parameters from the component, so any changes to the name through refactoring automatically updates the test.
The second parameter, class
is explicitly declared in the Aside
class. It is instead Attributes
parameter, that captures all unmatched parameters.
Passing new parameters to an already rendered component
Sometimes we want to test what happens when a component is re-rendered, possible with new parameters. This can be done using the cut.Render()
and the cut.SetParametersAndRender()
methods, for example:
[Fact(DisplayName = "Passing new parameters to Aside updates the rendered HTML correctly")]
public void Test002()
{
// Arrange - initial render of Aside
var cut = RenderComponent();
// Act - set the Header parameter and re-render the CUT
cut.SetParametersAndRender((nameof(Aside.Header), "HEADER"));
// Assert - Check that we have exactly one change since the first render,
// and that it is an addition to the DOM tree
cut.GetChangesSinceFirstRender()
.ShouldHaveSingleChange()
.ShouldBeAddition("HEADER");
// Arrange - Create a snapshot of the current rendered HTML for later comparisons
cut.SaveSnapshot();
// Act - Set the Header parameter to null again and re-render
cut.SetParametersAndRender((nameof(Aside.Header), null));
// Assert - Check that we have exactly one change since compared with the snapshot we took,
// and that it is an addition to the DOM tree.
cut.GetChangesSinceSnapshot()
.ShouldHaveSingleChange()
.ShouldBeRemoval("HEADER");
}
Some notes on Test002
above:
- The
cut.SetParametersAndRender()
method has the same overloads as theRenderComponent()
method. - The
ShouldHaveSingleChange()
method asserts that only a single difference is found by the compare method, and returns that diff object. - The
ShouldBeAddition()
method verifies that a difference is an addition with the specified content (doing a semantic HTML comparison). - The
cut.TakeSnapshot()
method saves the current rendered HTML for later comparisons. - The
cut.GetChangesSinceSnapshot()
compares the current rendered HTML with the one saved by theTakeSnapshot()
method.
Testing components with child content
The Aside.razor component listed in the previous section also has a ChildContent
parameter, so lets add a few tests that passes markup and components to it through that.
public class AsideTest : ComponentTestFixture
{
[Fact(DisplayName = "Aside should render child markup content correctly")]
public void Test003()
{
// Arrange
var content = "
I like simple tests and I cannot lie
";
// Act
// Act - render the Aside component with a child content parameter,
// which is constructed through the ChildContent helper method.
//
// This is equivalent to the follow Razor code:
//
//
//
I like simple tests and I cannot lie

//
var cut = RenderComponent(
ChildContent(content)
);
// Assert - verify that the rendered HTML from the Aside component matches the expected output.
cut.MarkupMatches($@"{content}");
}
[Fact(DisplayName = "Aside should render a child component correctly")]
public void Test004()
{
// Arrange - set up test data
var outerAsideHeader = "Hello outside";
var nestedAsideHeader = "Hello inside";
// Act - render the Aside component, passing a header to it
// and a component to its child content. The ChildContent helper
// method will pass the parameters it is given to the nested Aside
// component.
//
// This is equivalent to the follow Razor code:
//
//
//
//
var cut = RenderComponent(
(nameof(Aside.Header), outerAsideHeader),
ChildContent(
(nameof(Aside.Header), nestedAsideHeader)
)
);
// Assert - verify that the rendered HTML from the Aside component matches the expected output.
cut.MarkupMatches($@"
{outerAsideHeader}

{nestedAsideHeader}

");
}
}
- In
Test003
above we use theChildContent(...)
helper method to create a ChildContent parameter and pass that to theAside
component. - The overload,
ChildContent<TComponent>(...)
, used inTest004
, allows us to create a render fragment that will render a component (of typeTComponent
) with the specified parameters.
TheChildContent<TComponent>(...)
has the same parameter options as theRenderComponent<TComponent>
method has.
Testing components with EventCallback
parameters
To show how to pass an EventCallback
to a component under test, we will use the ThemedButton.razor, which looks like this:
<button @onclick="HandleOnClick"
class=@Theme?.Value
title=@Title?.Value
@attributes="Attributes">
@ChildContent
</button>
@code {
[Parameter(CaptureUnmatchedValues = true)]
public IReadOnlyDictionary<string, object>? Attributes { get; set; }
[CascadingParameter] public ThemeInfo? Theme { get; set; }
[CascadingParameter(Name = nameof(Title))] public ThemeInfo? Title { get; set; }
[Parameter] public RenderFragment? ChildContent { get; set; }
[Parameter] public EventCallback<MouseEventArgs> OnClick { get; set; }
private Task HandleOnClick(MouseEventArgs args) => OnClick.InvokeAsync(args);
}
The relevant part of ThemedButtonTest.cs looks like this:
public class ThemedButtonTest : ComponentTestFixture
{
[Fact(DisplayName = "When button is clicked, the OnClick event callback is triggered")]
public void Test001()
{
var wasCalled = false;
// Arrange - pass a lambda in as parameter to the OnClick parameter.
//
// This is equivalent to the follow Razor code:
//
// <ThemedButton OnClick="(_) => wasCalled = true"></ThemedButton>
var cut = RenderComponent<ThemedButton>(
EventCallback(nameof(ThemedButton.OnClick), (MouseEventArgs _) => wasCalled = true)
);
// Act - click the button in CUT
cut.Find("button").Click();
// Assert - check if callback was triggered
wasCalled.ShouldBeTrue();
}
}
Test001
above uses the EventCallback(parammeterName, callback)
helper method the generate a proper EventCallback
object. There are many overloads, that should enable all the normal scenarios that is possible via Razor code.
Testing components with cascading-value parameters
If a component under test accepts cascading values, like ThemedButton.razor listed above, we can pass one or more cascading values to it like so:
public class ThemedButtonTest : ComponentTestFixture
{
[Fact(DisplayName = "Themed button uses provided theme info to set class attribute")]
public void Test002()
{
// Arrange - create an instance of the ThemeInfo class to passs to the ThemedButton
var theme = new ThemeInfo() { Value = "BUTTON" };
// Act - Render the ThemedButton component, passing in the instance of ThemeInfo
// as an _unnamed_ cascading value.
//
// This is equivalent to the follow Razor code:
//
// <CascadingValue Value="theme">
// <ThemedButton></ThemedButton>
// </CascadingValue>
var cut = RenderComponent<ThemedButton>(
CascadingValue(theme)
);
// Assert - check that the class specified in the cascading value was indeed used.
cut.Find("button").ClassList.ShouldContain(theme.Value);
}
[Fact(DisplayName = "Named cascading values are passed to components")]
public void Test003()
{
// Arrange - create two instances of the ThemeInfo class to passs to the ThemedButton
var theme = new ThemeInfo() { Value = "BUTTON" };
var titleTheme = new ThemeInfo() { Value = "BAR" };
// Act - Render the ThemedButton component, passing in the instances of ThemeInfo
// as an _unnamed_ and a _named_ cascading value.
//
// This is equivalent to the follow Razor code:
//
// <CascadingValue Value="theme">
// <CascadingValue Name="Title" Value="titleTheme">
// <ThemedButton></ThemedButton>
// </CascadingValue>
// </CascadingValue>
var cut = RenderComponent<ThemedButton>(
CascadingValue(theme),
CascadingValue(nameof(ThemedButton.Title), titleTheme)
);
// Assert - check that the class and title specified in the cascading values was indeed used.
var elm = cut.Find("button");
elm.ClassList.ShouldContain(theme.Value);
elm.GetAttribute("title").ShouldContain(titleTheme.Value);
}
}
Test002
above uses theCascadingValue(object value)
helper method to pass an unnamed cascading value to the CUT.Test003
above demonstrates how multiple (named) cascading values can be passed to a component under test.
Testing components that use on IJsRuntime
It is not uncommon to have components use Blazor's JSInterop functionality to call JavaScript, e.g. after first render.
To make it easy to mock calls to JavaScript, the library comes with a IJsRuntime
mocking helper, that allows you to specify return how JSInterop calls should be handled, and to verify that they have happened.
If you have more complex mocking needs, you could look to frameworks like Moq.
To help us test the Mock JSRuntime, we have the WikiSearch.razor component, which looks like this:
@inject IJSRuntime jsRuntime

@searchResult

@code {
string searchResult = string.Empty;
// Assumes the following function is available in the DOM
//
protected override async Task OnAfterRenderAsync(bool firstRender)
{
if (firstRender)
{
searchResult = await jsRuntime.InvokeAsync<string>("queryWiki", "blazor");
StateHasChanged();
}
}
}
The WikiSearchTest.cs looks like this:
public class WikiSearchTest : ComponentTestFixture
{
[Fact(DisplayName = "WikiSearch renders an empty P element initially")]
public void Test001()
{
// Arrange
// Registered the MockJsRuntime in "Loose" mode with the service provider used when rendering components.
// JsRuntimeMockMode.Loose is the default. It configures the mock to just return the default
// value for whatever is requested in a InvokeAsync call if no call has explicitly been set up.
var jsMock = Services.AddMockJsRuntime();
// Act - render the WikiSearch component
var cut = RenderComponent<WikiSearch>();
// Assert
// Check that the components initial HTML is as expected
// and that the mock was called with the expected JS identifier and arguments.
cut.MarkupMatches("

");
jsMock.VerifyInvoke("queryWiki").Arguments.Single().ShouldBe("blazor");
}
[Fact(DisplayName = "On first render WikiSearch uses JSInterop to query wiki and display the result")]
public void Test002()
{
// Arrange
// Registered the MockJsRuntime in "strict" mode with the service provider used when rendering components.
// JsRuntimeMockMode.Strict mode configures the mock to throw an error if it receives an InvokeAsync call
// it has not been set up to handle.
var jsMock = Services.AddMockJsRuntime(JsRuntimeMockMode.Strict);
// Set up the mock to handle the expected call
var expectedSearchResult = "SEARCH RESULT";
var plannedInvocation = jsMock.Setup<string>("queryWiki", "blazor");
// Render the WikiSearch and verify that there is no content in the paragraph element
var cut = RenderComponent<WikiSearch>();
cut.Find("p").InnerHtml.ShouldBeEmpty();
// Act
// Use the WaitForNextRender to block until the component has finished re-rendered.
// The plannedInvocation.SetResult will return the result to the component is waiting
// for in its OnAfterRender from the await jsRuntime.InvokeAsync<string>("queryWiki", "blazor") call.
WaitForNextRender(() => plannedInvocation.SetResult(expectedSearchResult));
// Assert
// Verify that the result was received and correct placed in the paragraph element.
cut.Find("p").InnerHtml.ShouldBe(expectedSearchResult);
}
}
Test001
just injects the mock in "Loose" mode. It means it will only returns adefault(TValue)
for calls toInvokeAsync<TValue>(...)
it receives. This allows us to test components that expects aIJsRuntime
to be injected, but where the test we want to perform isn't dependent on it providing any specific return value.In "Loose" mode it is still possible to call
VerifyInvoke(identifier)
and assert against the expected invocation.Test002
injects and configures the mock in strict mode. That requires us to configure all the expected calls the mock should handle. If it receives a call it has not been configured for, an exception is thrown and the test fails.The
WaitForNextRender(Action)
helper method is used to block until a (async) render completes, that the action passed to it has triggered. InTest002
we trigger a render by setting the result on the planned invocation, which causes theawait jsRuntime.InvokeAsync<string>("queryWiki", "blazor")
call in the CUT to complete, and the component to trigger a re-render by calling theStateHasChanged()
method.
Verifying element references passed to InvokeAsync
If you want to verify that a element reference (ElementReference
) passed to a IJsRuntime.InvokeAsync call is references the expected DOM element, you can do so with the ShouldBeElementReferenceTo()
assert helper.
For example, consider the FocussingInput.razor component, which looks like this:
@inject IJSRuntime jsRuntime
<input @ref="_inputRef" @attributes="Attributes" />
@code {
private ElementReference _inputRef;
[Parameter(CaptureUnmatchedValues = true)]
public IReadOnlyDictionary<string, object>? Attributes { get; set; }
protected override async Task OnAfterRenderAsync(bool firstRender)
{
if (firstRender)
{
await jsRuntime.InvokeVoidAsync("document.body.focus.call", _inputRef);
}
}
}
The the FocussingInputTest.cs looks like this:
public class FocussingInputTest : ComponentTestFixture
{
[Fact(DisplayName = "After first render, the new input field has focus")]
public void Test001()
{
// Arrange - add the IJsRuntime mock
var jsRtMock = Services.AddMockJsRuntime();
// Act - render the FocussingInput component, causing
// the OnAfterRender(firstRender: true) to be called
var cut = RenderComponent<FocussingInput>();
// Assert
// that there is a single call to document.body.focus.call
var invocation = jsRtMock.VerifyInvoke("document.body.focus.call");
// Assert that the invocation received a single argument
// and that it was a reference to the input element.
var expectedReferencedElement = cut.Find("input");
invocation.Arguments.Single().ShouldBeElementReferenceTo(expectedReferencedElement);
}
}
The last line verifies that there was a single argument to the invocation, and via the ShouldBeElementReferenceTo
checks, that the <input />
was indeed the referenced element.
Testing components with injected dependencies
The demonstrate service injection, lets refactor the FetchData.razor component that comes with the default Razor app template, to make it more testable:
Extract an interface from WeatherForecastService, name it IWeatherForecastService, and have
FetchData
take a dependency on it.Extract the

inside theelse
branch in the FetchData.razor component into its own component. Lets name it ForecastDataTable.In the FetchData.razor, pass the variable
forecasts
to the ForecastDataTable component.
Now we just need a MockForecastService.cs. It looks like this:
internal class MockForecastService : IWeatherForecastService
{
public TaskCompletionSource<WeatherForecast[]> Task { get; } = new TaskCompletionSource<WeatherForecast[]>();
public Task<WeatherForecast[]> GetForecastAsync(DateTime startDate) => Task.Task;
}
With the mock in place, we can write the FetchDataTest.cs, which looks like this:
public class FetchDataTest : ComponentTestFixture
{
[Fact(DisplayName = "Fetch data component renders expected initial markup")]
public void Test001()
{
// Arrange - add the mock forecast service
Services.AddSingleton<IWeatherForecastService, MockForecastService>();
// Act - render the FetchData component
var cut = RenderComponent<FetchData>();
// Assert that it renders the initial loading message
var initialExpectedHtml = @"
Weather forecast

This component demonstrates fetching data from a service.

Loading...
";
cut.MarkupMatches(initialExpectedHtml);
}
[Fact(DisplayName = "After data loads it is displayed in a ForecastTable component")]
public void Test002()
{
// Setup the mock forecast service
var forecasts = new[] { new WeatherForecast { Date = DateTime.Now, Summary = "Testy", TemperatureC = 42 } };
var mockForecastService = new MockForecastService();
Services.AddSingleton<IWeatherForecastService>(mockForecastService);
// Arrange - render the FetchData component
var cut = RenderComponent<FetchData>();
// Act - pass the test forecasts to the component via the mock services
WaitForNextRender(() => mockForecastService.Task.SetResult(forecasts));
// Assert
// Render an new instance of the ForecastDataTable, passing in the test data
var expectedDataTable = RenderComponent<ForecastDataTable>((nameof(ForecastDataTable.Forecasts), forecasts));
// Assert that the CUT has two changes, one removal of the loading message and one addition which matched the
// rendered HTML from the expectedDataTable.
cut.GetChangesSinceFirstRender().ShouldHaveChanges(
diff => diff.ShouldBeRemoval("
Loading...
"),
diff => diff.ShouldBeAddition(expectedDataTable)
);
}
}
In
Test001
we use theServices.AddSingleton
method to register the dependency and the performs a regular "initial render" verification.Test002
creates a new instance of the mock service and registers that with the the service provider. It then renders the CUT and usesWaitForNextRender
to pass the test data to the mock services task, which then completes and the CUT gets the data.In the assert step we expect the CUT to use a
ForecastDataTable
to render the forecast data. Thus, to make our assertion more simple and stable to changes, we render an instance of theForecastDataTable
use that to verify that the expected addition after the CUT receives the forecast data is as it should be.
Dispatching @on-events
during testing
In the previous sections we have seen a few examples of method calls that trigger @on-event
handlers, e.g. cut.Find(selector).Click()
that triggers the @onclick
event handler attached to the element that matches the search query.
The following triggers are currently available in PascalCase, without the @on
-prefix. E.g. the @onbeforeactivate
event is available as BeforeActivate()
in various overloads.


--- breadcrumbs: ["Families", "Example two"] title: Fonts with file-size benefits description: One of the most tangible advantages of variable fonts lies in their nimble performance. Traditionally, every additional style of a digital typeface meant an additional font file. By contrast, a variable font encompasses all styles in a _single_ file. On the web, this translates into faster load times—and happier users. --- {% assign roboto = site.data.examples.roboto-size %}


Introduction to Probability Models
Lecture 18
Qi Wang, Department of Statistics
Oct 1, 2018
Reminders
- The fourth quiz will be on this Wednesday, Oct 3
Example 1
Consider a game where we will roll a fair die. We will roll it until we get a $5$.
What is the probability that it will take $3$ rolls to get the $5$?
Think about:
- Are the subsequent rolls independent?
- What about the probability of success on each roll?
- Do we have a set number of trials?
GEOMETRIC RANDOM VARIABLE
Characteristics of the Geometric Distribution
- The definition of $X$ : the number of trials to get the first success
- Support: $\{1, 2, \cdots\}$, NOTE: NO ZERO!
- Parameter: $p$, the probability of success in one trial
- PMF: $P_X(x) = p(1-p)^{x - 1}$
- Expected Value: $E[X] = \frac{1}{p}$
- Variance: $Var(X) = \frac{1 - p}{p^2}$
- $X \sim Geom(p)$
Example 2
Suppose Dunphy is really bad at tossing a Frisbee and unfortunate hits people walking by at a rate of 1 out of every 5 people.
- What is the probability that his first accidental hitting is the $6_{th}$ or $7_{th}$ person to walk by?
- What is the probability that more than 7 people walk past before he hits one with the Frisbee?
Important Properties for the Geometric Distribution
- Tail Probability formula: $P(X > k) = (1 - p)^k$
- Memoryless Property: $P(X > s + t| X > s) = P(X > t)$ and $P(X < s + t| X > s) = P(X < t)$
Example 2 continued
- 3. Four people have walked past Dunphy and none have been hit by a Frisbee. What is the probability that at most 9 walk by until the first person is hit by a Frisbee?
- 4. Four people have walked past Dunphy and none have been hit by a Frisbee. What is the probability that at least 10 walk by until the first person is hit by a Frisbee?
Example 3
Shaq is shooting free throws in the gym. He intends to stay until he makes one. His probability of making one on any free throw is 0.527. Let X be the number of attempts until he makes one.
- Distribution, parameter, support?
- Expected number of shots until he makes one?
- Probability he makes his first shot on the $4_{th}$ try?
- Probability it takes him at least 4 shots to make $1_{st}$?
- Probability it takes him exactly 4 shots if he already missed the first?
- Probability it takes him at least 4 shots if he already missed the first?
Example 4
Bugcatcher Nathan is standing by the side of the road with his Caterpie, ready to start battling other trainers with his Pokémon. Since he’s just starting out, Nathan has a very low chance of winning each battle, just 16%. Let X be the number of battles Nathan must endure with his Caterpie before he finally wins his first.
- What is the support, distribution, and parameter(s) of X
- Nathan makes 100 Pokédollars for every win, but has to pay 20 Pokédollars for each loss. Luckily, Nathan has deep pockets. How much money would you expect Nathan to have won, or lost, in total after his first win?
- If Nathan has battled 7 trainers so far today, what is the probability that he faces at least 10 total before he earns his first win?


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GatewayBOT08-Jan-20 05:51 AM
[dscrd-hush] <AkiraX> How will we send to exchange then?
[dscrd-hush] <AkiraX> Z2z
GatewayBOT08-Jan-20 06:43 AM
[dscrd-hush] <MorganJekyll> So is there an actual working HUSH messaging app?
[dscrd-hush] <MorganJekyll> And does it have a built in feature to send btc and others with atomic swaps? Because that’s the killer app right there
GatewayBOT08-Jan-20 10:27 AM
[dscrd-hush] <gilardh> @MorganJekyll Regarding HUSH messaging app, we have put a few bricks on SilenceDragonAndroid (SDA) and SilentDragonLite (SDL). We are working hard to strengthen network security and eradicate metadata leaks. A secure and private base is important for building private messaging applications, which is our goal.
HUSH fork of KMD. Contribute to MyHush/hush3 development by creating an account on GitHub.
GatewayBOT08-Jan-20 01:17 PM
[dscrd-hush] <dukeleto> @MorganJekyll all of our GUI wallets support sending the encrypted memo field back and forth already (SD, SDL, SDA). We have a mock GUI for our android app SDA that is furthest along, that needs to be tied to the backend. All the pieces are there, but all the glue and shiny stuff between them is not If you want to help, we got plenty to do and we pay bounties
GatewayBOT08-Jan-20 07:08 PM
[dscrd-hush] <SaraStocks> Hey everyone
GatewayBOT08-Jan-20 07:48 PM
[dscrd-hush] <heguli97> Hello
GatewayBOT08-Jan-20 08:39 PM
[dscrd-hush] <dukeleto> !tip 11 random users 55 hush
[dscrd-hush] <tip.cc> :HUSH: @dukeleto sent @Bithorny, @brbillionaire, @Chewy, @Karatacus, @lolherpes, @noca221, @prigo, @ribbutt, @sgc1987, @superman and @Trusted43 5.00 HUSH (≈ $0.21) each :cloud_rain:.
 Use it well :hush_white: :hush_puppy: :hush_dark:
GatewayBOT08-Jan-20 08:53 PM
[dscrd-hush] <superman> @dukeleto thanks, we wil
GatewayBOT08-Jan-20 11:51 PM
[dscrd-hush] <Berg> For those who saw the announcement in #-announcements- I cannot stress enough how valuable this listing would be for HUSH.
This is not a mere market listing, but an opportunity for HUSH to be accepted by merchants worldwide as a form of payment in both transparent AND private shielded transactions. This would be monumental for HUSH.
Please vote:
https://cryptocurrencycheckout.com/vote
Also, please collect the airdrop of free HUSH below (edited)


Binary deserialization context class. More...
#include <PxSerialFramework.h>
Public Member Functions | |
| virtual PxBase * | resolveReference (PxU32 kind, size_t reference) const =0 |
| Retrieves a pointer to a deserialized PxBase object given a corresponding deserialized reference value. More... | |
| template<typename T > | |
| void | translatePxBase (T *&base) |
| Helper function to update PxBase pointer on deserialization. More... | |
| PX_INLINE void | readName (const char *&name) |
| Helper function to read a name from the extra data during deserialization. More... | |
| template<typename T > | |
| PX_INLINE T * | readExtraData (PxU32 count=1) |
| Function to read extra data during deserialization. More... | |
| template<typename T , PxU32 alignment> | |
| PX_INLINE T * | readExtraData (PxU32 count=1) |
| Function to read extra data during deserialization optionally aligning the extra data stream before reading. More... | |
| PX_INLINE void | alignExtraData (PxU32 alignment=PX_SERIAL_ALIGN) |
| Function to align the extra data stream to a power of 2 alignment. More... | |
Protected Member Functions | |
| PxDeserializationContext () | |
| virtual | ~PxDeserializationContext () |
Protected Attributes | |
| PxU8 * | mExtraDataAddress |
Binary deserialization context class.
This class is used to resolve references and access extra data during deserialization. It is mainly used by the serialization framework. Except for custom serializable types, users should not have to worry about it.
|
inlineprotected |
|
inlineprotectedvirtual |
|
inline |
Function to align the extra data stream to a power of 2 alignment.
This function is assumed to be called within the implementation of PxSerializer::createObject.
|
inline |
Function to read extra data during deserialization.
This function is assumed to be called within the implementation of PxSerializer::createObject.
|
inline |
Function to read extra data during deserialization optionally aligning the extra data stream before reading.
This function is assumed to be called within the implementation of PxSerializer::createObject.
|
inline |
Helper function to read a name from the extra data during deserialization.
This function is assumed to be called within the implementation of PxSerializer::createObject.
|
pure virtual |
Retrieves a pointer to a deserialized PxBase object given a corresponding deserialized reference value.
This method is assumed to be called in the implementation of PxSerializer::createObject in order to update reference values on deserialization.
To update a PxBase reference the corresponding deserialized pointer value needs to be provided in order to retrieve the location of the corresponding deserialized PxBase object. (PxDeserializationContext::translatePxBase simplifies this common case).
For other kinds of references the reverence values need to be updated by deduction given the corresponding PxBase instance.
| [in] | kind | What kind of reference this is (PX_SERIAL_REF_KIND_PXBASE, PX_SERIAL_REF_KIND_MATERIAL_IDX or custom kind) |
| [in] | reference | Deserialized reference value |
|
inline |
Helper function to update PxBase pointer on deserialization.
References PX_SERIAL_REF_KIND_PXBASE.
|
protected |


I am an Engineering Student pursuing B.Tech Information Technology in Thiagarajar college of Engineering, Madurai,
My name is Suganthi K.My native is Nagercoil, Kanyakumari.As everyone has I had a very happy childhood with a very happy education too. I did my schooling in Adarsh Vidya Kendra which was my temple of learning.
I am very much interested in Machine Learning.ML is a blooming technology which can autoamte and make wonders.My area of interest is Data Science.


Construction projects are currently notorious for being behind schedule, over budget, and dangerous for construction workers. According to the Bureau of Labour Statistics’ 2015 Census of Fatal Occupational Injuries, construction is the leading industry in worker injuries and fatalities. Autonomous technology can have a huge positive impact on construction, increasing efficiency and lowering worker exposure to dangerous situations. However, construction sites are ad-hoc environments with constantly changing temporary roads, materials being moved, and structures being built. This can be a very difficult environment for autonomous solutions to navigate.
In our Capstone Project we aim to build a solution that autonomously builds an accurate and up to date 3D model of a given construction site. This will be done using a drone. The site model will contain a 3D spatial occupancy grid as well as labelled roads and points of interest. This information will be provided to other systems on the site wirelessly, enabling autonomous solutions to navigate the site and work together.
With just a few days leading up to symposium, the project reaches its final stage as the hardware/software platform is locked for demo day. Some refinement on the data pipeline as well as full integration of the GoPro onto the drone chassis were the final touches required before demo day. The image below shows the final hardware configuration of the drone, as it will be presented on demo day.
Our final drone hardware.
The team collected its final dataset this past weekend and has collected video footage of the drone in action. For symposium, the team plans to have a short (1min) clip on display alongside the poster board, both are shown below. Additionally, the aim is to include two interactive elements: a display showing the 3-D Model of the site and an iPad with the web app loaded and ready for annotation. You may notice some blank space left on the poster, this is simply to allow for some space for the displays to sit on the table without obscuring any of the poster content.
Symposium poster.
The final revision of the annotation web app is also now complete, a screenshot is included below that gives an impression of the UI. The web app is an essential last step in the data pipeline as it allows for the addition of POIs and roads to the site model, creating a richer dataset for autonomous technologies to use as opposed to just the collision model made available through the .stl file.
Final web app.
The drone has been repaired and is ready for flight. The team was fortunate enough to find a a 100m x 100m construction site. Mihai showed expert drone control and the team was able to collect two sets of data through manual flight. The combined data sets were run through the pipeline on AWS, creating outstanding results.
Point cloud orthographic photo.
The data is captured using a GoPro Hero5 as the camera issues are still preventing the team from being able to take pictures faster than one picture in 12 seconds. Bonus feature that the team got to test is the automatic landing of the drone when the battery levels are critically low. Although that cost the drone one of its standing carbon fiber legs, it's still in good shape and ready to fly next weekend for further data collection.
Currently the website is going through design critiques and restructuring to improve user experience and the overall interface. The team is also thinking of creative ways to prepare media and data for the Symposium. We thought of a few fun things to show, come check us out on March 23rd at the Davis Center.
Over the past week Hugo worked tirelessly to get the camera hardware to communicate through ROS and be able to capture images in flight. From discussions with E-Con Systems, the company that provided the camera solution, it should be able to take full resolution (13MP) stills at 9 frames per second. However, after receiving the source code for the camera mid-February, the camera can only do one frame every 12 seconds. Thus, this solution is deemed insufficient and alternatives have to be considered.
A lot of progress made to prepare the drone for flight. Below is the set up for the tethered dynamic testing. We used this to tune parameters as well as get some experience controlling the drone.
Rishab tightening the rotor nuts before testing.
Here is some footage of our drone in action:
Second free flight after static and tethered dynamic testing lasted approximately 15 seconds until the drone crashed into the wall, breaking the carbon fiber rotor arm as well as one of the motors. Although a set back, the team is optimistic to have the drone up an running by the end of the week to start testing outside far away from walls that come out of nowhere.
Although short flight, the drone was able to collect 15 images which are ran through the data processing pipeline. The results are not expected to be good from a small amount of images as well as unsteady flight. However, despite prediction, a lot of features were captured. As can be seen from the point cloud below,
Point cloud from the first (indoor) flight test.
Communicating with the drone for autonomous flight requires a mission to be loaded onto the drone. We can simulate full autonomy, however we are currently working on establishing a link with the drone through ROS to make it a reality. The video shows the drone take-off and completion of a mission set out by multiple waypoints around 8 Hickory St West, after visiting every waypoint the drone returns to launch point.
The hardware platform is complete and ready for testing, with the exception of the camera. Manual flight testing will begin shortly and will expose any errors in calibration or setup that may have occurred.
Final Drone Hardware (Excluding camera)
The camera hardware is currently held back by issues the team has had with interfacing with it. The camera manufacturer has provided the team with the code required to interface with it, but there is work still yet to be done in order to fully integrate it within the drone’s software stack.
This is the portion of the pipeline that plans the path that the drone should take given an address or GPS coordinates of the construction site location. So far, the mission planner code is able to generate a set of GPS coordinates that represent the drone’s proposed path. Further work is needed to determine the optimal spacing of points to achieve desired overlap between images. Additionally, the code will eventually need to interface with the drone control software in order to translate the set of points into actual drone movements.
Mission Planner
In the context of the project, “Drone Control” refers to the software that will run on the drone itself that instructs the flight control software about what to do (fly to waypoint, take picture, etc.). At the moment, the code runs inside a simulated environment. Some work is left to translate this work into code that will make the drone fly.
After a series of design meetings the previous week, the ground work was performed both from a hardware and software perspective. Point cloud filtering, website backend and frontend interfaces, drone flight simulation and hardware setup and bringup were all performed by the team members to ensure that no critical component was left unattended.
Hardware Setup/Bringup
After 3D printing the necessary brackets, the drone was assembled and connected to the provided base station running on a laptop and obtained from Ardupilot. This confirmed that all drone modules worked as expected. The next step is to connect the controller to the drone so that manual flight can be performed.
Point Cloud Filtering
To filter point clouds, the point cloud is first mapped to an image, where the (x,y) coordinates are mapped to (i,j) indices and the z-coordinate becomes the intensity. This method assumes that the (x,y) coordinates do not contain erroneous data, and that the filtering will be performed on the height data. This simplifies the filtering process while maintaining an accurate representation of the data.
Given a set resolution, the (x,y) coordinates of each point is mapped to an (i,j) index tuple, and once each point has been mapped, inpainting is applied to avoid image pixels having no associated data. Without inpainting, any filtering method would introduce more erroneous data since it would rely on non-existent data for smoothing, edge enhancement, outlier removal, etc.
The data is then filtered through a given method, which will be decided upon based on the obtained data from testing. The filtered image can then be mapped back to a point cloud for further data handling (exporting to STL, adding GPS data, etc.).
POI Website Interface
In order to add the roads and Points of Interest(POI) on the map, a web interface has been implemented where a user can click and connect different points over an orthophoto or the generated point cloud.
Website Prototype
As shown in the picture above, the interface still requires design work but feature-wise, the website is almost complete. The roads are saved and can be reload by accessing the website. Roads can also be added, deleted, and modified by the user at any point in the process.
Ardupilot Simulation
The ROS-enabled Ardupilot simulation was also setup during the week and a pre-built model of a drone was used to perform a given mission plan. From this initial testing, further work can be performed on the mission plan generation, as well as properly linking the simulation with real hardware.
The second term (Jan - April 2018) begins with mechanical and hardware assembly of the drone kit. Progressing towards enabling manual flight using an RC control.
We printed the mounting bracket for the camera hardware and the design for the anti-vibration bed for the controller is complete. Both the mount and the bed dampen the vibration introduced by the drone’s motors to get rid of the noise that can corrupt our location measurements.
Lynxmotion HQuad500
Today, according to Global Projects Database, large projects in the construction industry are late by an average of 20% than originally scheduled with some up to nine years. According to the same study the projects are also are over budget by an average 80% with some as high as 650% [1]. In addition, almost 50 workers are injured every minute of the workweek and 17 deaths occur per day in the USA, according to OSHA [2].
Despite technological improvements, many projects are over-budget, over-time and dangerous. Autonomappr aims to provide an accurate site model with labelled point of interests to effectively increase efficiency and mitigate safety concerns by enabling autonomous technology on a construction site. The project objectives are outlined below.
Autonomous Data Gathering
Build a 3D mesh representation of the construction site
Enable road and point of interest marking
Generate approximate volume measurements
Make results available through an API
The team defined constraints and criteria selected to be successful and competitive with the current market.
| Cost | Physical platofrm costs less than $3000 |
| Mass | Physical platofrm weighs less than 6kg |
| Accuracy | 3D point cloud is accurate within 15cm |
| Speed | Able to fully refresh site model twice per day (for area 100x100m) |
| Robustness | Able to operate on all terrains typically found on a construction site |
| Autonomy | Gathering of raw terrain data must be autonomous |
| UX | Enable end users to label roads and points of interest on the 3D model |
| Stretch Goal | Automatic road and point of interest detection through semantic segmentation |
| Resolution | Exceed a point cloud density of 100 points per square meter |
Since September of 2017, the project progressed through initial ideas to a final design for mechanical, hardware and software components. The solution revolves around a multi-rotor drone that inspects the construction site from above, capturing images and topology data.
The data processing pipeline turns the raw data into a usable site model that is useful for end users and other autonomous robots onsite. The team is on schedule to present at the Capstone Symposium in March of 2018.
[1] R. Agarwal, S. Chandrasekaran and M. Sridhar, "Capital Projects & Infrastructure - Imagining construction's digital future," McKinsey&Company, June 2016. [Online]. Available: https://www.mckinsey.com/industries/capital-projects-and- infrastructure/our-insights/imagining-constructions-digital-future. [Accessed 16 October 2017]
[2] J. Moody, "A LOOK AT THE ROI OF SAFETY," 12 September 2017. [Online]. Available: https://www.safetyservicescompany.com/topic/uncategorized/look-roi- safety/. [Accessed 16 October 2017].


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Leah J. Barnes
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Hangman
RPG Game
Trivia Game
Rutger's Info Widget
Rock Paper Scissors


Explanation
Null Hypothesis (H
0
)
{{ include.null_explanation }}
Alternate Hypothesis (H
A
)
{{ include.alternate_explanation }}


Post edited 2 x times, last by
BrainFooLong
Administrator
Topicstarter
T3RRORTOAST
Community Manager
It is possible to add a "delete friend" button on the profile?
Example:
http://img3.fotos-hochladen.net/uploads/unbenannt2nlufo0516h.jpg
BrainFooLong
Administrator
Possible yes, but i don't see an advantage. You already have a friendlist where you can see an delete all at once.
It's quicker and easier. Instead of going to your profile page, then going to the friends page, and then searching for the soldier you want to delete.
I would welcome a feature like this.
I agree with Terror and Jumpy. :-)


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Greplr is a hyperlocal search platform that will fulfill all your needs on a single platform.
Greplr is a one of it’s kind search engine for hyper-local services and products. There are multiple apps and services that are catering to the hyper-local domain, like calling cabs, ordering food, discovering restaurants, fetching grocery, or calling electricians or cleaners. These services are all provided by different providers, fragmented into lots of different apps and websites. Greplr searches across all these platforms to provide a cohesive platform within one app to discover and fullfill all your hyperlocal needs.
Currently Greplr is able to find and book cabs from Uber and TFS near you, search Bus tickets to and from all Indian cities, and book domestic and international flight tickets. Also Greplr lets you discover Restaurants, Bars and Cafes around you, and can find you restaurants from where you can order using Foodpanda. Greplr shows the latest movies and plays running in your city, and also brings the top offers and deals on various shopping platforms like Flipkart and Amazon. You can use Greplr to search across e-commerce websites, as well.


Applications are open for the 2017 TALENT course on Theory for exploring Nuclear Structure experiments. The recently established initiative, Nuclear TALENT (Training in Advanced Low Energy Nuclear Theory), see also http://www.nucleartalent.org, a multi-national network of several European and North American institutions, aims to develop a broad curriculum that will serve as a platform for cutting-edge theory of nuclei and their reactions.
This year the Nuclear TALENT initiative organizes a course on "Theory for Exploring Nuclear Structure Experiments" to be held at at The European Center for Theoretical Nuclear Physics and Related Areas (ECT*), Trento, Italy from July 3 to July 21 2017.
The deadline for applications is April 15, 2017. For more information on how to apply see http://ectstar.eu/node/797, see also http://ectstar.eu/node/2240. A detailed content list can be found at http://nucleartalent.github.io/NuclearStructure/doc/web/course.html.
The target groups are Master of Science and PhD students and early post-doctoral researchers, both experimentalists and theorists interested in models for nuclear structure, phenomenological techniques for interpreting and predicting the structure of stable as well as exotic nuclei. More experienced researchers may apply, but will be considered only on a fully-self-supported basis if numbers and space permit. Local support is available for at most 15-20 participants.
For additional information on each of the courses, please see http://www.nucleartalent.org. Prior to the TALENT course, the ECT* organizes a Doctoral Training program on Microscopic Theories of Nuclear Structure, Dynamics and Electroweak Currents from June 12 to June 30, 2017. The doctoral training program can be combined with the TALENT course. Applicants interested in attending the doctoral training program can find more information at http://ectstar.eu/node/2238.


---
layout: post
title: Arc welding
date: '2007-11-07T22:41:00.000+01:00'
author: Steven Van Acker
tags:
- Welding
modified_time: '2009-02-08T22:12:34.245+01:00'
blogger_id: tag:blogger.com,1999:blog-5513234137363262204.post-3144047633077310615
blogger_orig_url: http://www.singularity.be/2007/11/arc-welding.html
---
This year I enrolled in an arc welding course. If you've read this site often enough, you will probably not be surprised why I'm doing this :)
The course started september 4th with classes every tuesday from 18.30 till 22.00.
Here are some pictures of workpieces I brought home:
[G2:12452]
Booth 7, 2.5mm Lastek electrode 008 (fast): surface at 80A, outer corner at 72A, inner corner at 88A (when welding flat)
Booth 7, 2.5mm Lastek electrode 001 (slow): outer corner at 75A, inner corner at 95A (when welding at 45degrees)
the inner corner needs to be welded VERY closely, to avoid slag inclosure


+++ title = "Tapas thingies" slug = "tapas-thingies" date = 2007-02-20T15:00:00+10:00 tags = ["crazy-consumptions", "spicy"] locations = ["mexico/mexico-city"] draft = false summary = """
Not sure exactly what they were — kind of a big round taco, covered in meat and fish, and salad and salsa. Anyway, I got one of these in the street for just 8 pesos, near Hostel Amigo, and I gotta say it tasted superb, and it was easily enough to fill me up for lunch!
""" +++Not sure exactly what they were — kind of a big round taco, covered in meat and fish, and salad and salsa. Anyway, I got one of these in the street for just 8 pesos, near Hostel Amigo, and I gotta say it tasted superb, and it was easily enough to fill me up for lunch!


Uniform kernel alignment puts equal weight to each kernel.
\[\mathbf{K}_{\mu} = \sum_q \mathbf{K}_{q}\]
-
class
mklaren.mkl.uniform.
UniformAlignment
¶ -
__call__
(i, j)¶ Access portions of the combined kernel matrix at indices i, j.
Parameters: - i – (
int
) or (numpy.ndarray
) Index/indices of data points(s). - j – (
int
) or (numpy.ndarray
) Index/indices of data points(s).
Returns: (
numpy.ndarray
) Value of the kernel matrix for i, j.- i – (
-
__getitem__
(item)¶ Access portions of the kernel matrix generated by
kernel
.Parameters: item – ( tuple
) pair of: indices or list of indices or (numpy.ndarray
) or (slice
) to address portions of the kernel matrix.Returns: ( numpy.ndarray
) Value of the kernel matrix for item.
-
fit
(Ks)¶ Learn low-rank approximations and regression line for kernel matrices or Kinterfaces.
Parameters: Ks – ( list
) of (numpy.ndarray
) or of (Kinterface
) to be aligned.
-
-
class
mklaren.mkl.uniform.
UniformAlignmentLowRank
¶ Uniform kernel alignment when kernels are represented by low-rank approximations.
-
__call__
(i, j)¶ Access portions of the combined kernel matrix at indices i, j.
Parameters: - i – (
int
) or (numpy.ndarray
) Index/indices of data points(s). - j – (
int
) or (numpy.ndarray
) Index/indices of data points(s).
Returns: (
numpy.ndarray
) Value of the kernel matrix for i, j.- i – (
-
__getitem__
(item)¶ Access portions of the kernel matrix generated by
kernel
.Parameters: item – ( tuple
) pair of: indices or list of indices or (numpy.ndarray
) or (slice
) to address portions of the kernel matrix.Returns: ( numpy.ndarray
) Value of the kernel matrix for item.
-


This class is a shallow wrapper for std::random. To use this class, make an instance of RandGen with a given seed. Call uniDist anytime you need a random number.
More...
#include <RandGen.h>
|
| | RandGen () |
| | Initializes a new instance of the RandGen class with a random seed. More...
|
| |
| | RandGen (std::string *seed) |
| | Initializes a new instance of the RandGen class. More...
|
| |
|
| RandGen (const RandGen &generator)=default |
| |
|
| RandGen (RandGen &&generator)=default |
| |
|
RandGen & | operator= (const RandGen &generator)=default |
| |
|
RandGen & | operator= (RandGen &&generator)=default |
| |
| std::string | getSeed () |
| | Gets the seed of the Random Generator. More...
|
| |
| void | setSeed (std::string *seed) |
| | Sets the seed of the Random Generator. More...
|
| |
| double | uniDist (double min, double max) |
| | Creates a uniform distribution between [min, max) Throws if the provided min is not less than the max. More...
|
| |
|
|
std::string * | m_seedString |
| |
|
std::mt19937 * | m_generator |
| |
|
std::uniform_real_distribution< double > * | m_uniDistributor |
| |
This class is a shallow wrapper for std::random. To use this class, make an instance of RandGen with a given seed. Call uniDist anytime you need a random number.
◆ RandGen() [1/2]
Initializes a new instance of the RandGen class with a random seed.
◆ RandGen() [2/2]
| RandGen::RandGen |
( |
std::string * |
seed | ) |
|
|
explicit |
Initializes a new instance of the RandGen class.
- Parameters
-
| seed | The seed for the Generator. |
◆ getSeed()
| std::string RandGen::getSeed |
( |
| ) |
|
Gets the seed of the Random Generator.
- Returns
◆ setSeed()
| void RandGen::setSeed |
( |
std::string * |
seed | ) |
|
Sets the seed of the Random Generator.
- Parameters
-
| seed | New seed that we are setting on the engine. |
◆ uniDist()
| double RandGen::uniDist |
( |
double |
min, |
|
|
double |
max |
|
) |
| |
Creates a uniform distribution between [min, max) Throws if the provided min is not less than the max.
- Parameters
-
| min | The minimum number that can be returned. |
| max | The maximum number that can be returned. |
- Returns
The documentation for this class was generated from the following files:
- C:/Programming/Cpp/GameBackbone/GameBackbone/GameBackboneSln/GameBackbone/Include/GameBackbone/Util/RandGen.h
- C:/Programming/Cpp/GameBackbone/GameBackbone/GameBackboneSln/GameBackbone/Source/Util/RandGen.cpp


VenPep provides customer centric technology solutions which are simple, meets the market trends and solves the purpose.
Established in 2012, VenPep helps build applications for organizations using the best in class software technologies and have an eye to include the right mix of business intelligence, machine learning and big-data in the digital transformation of businesses.
With a team of 38 staffs, we are a group of management professionals, system architects, engineers, functional consultants and database architects working together to digitally transform SMEs and take them to the next level.
At VenPep, we pride ourselves on being able to handle the domain driven insights for our clients, seamlessly integrating the both for time-sensitive growth and have handled over 100 interesting technology development projects.
Our team has experience in working across multiple industries and functional areas in various countries - enabling us to bring in fresh ideas, learnings and a strategic perspective to every engagement.
VenPep has won 3 national awards in India from IBM, Economic Times and also the prestigious YourStory’s TECH30 - top 30 fast growing technology companies in India.


应用¶
$ npm install @feathersjs/feathers --save
The core @feathersjs/feathers
module provides the ability to
initialize new Feathers application instances. It works in Node, React
Native and the browser (see the Feathers 客户端 chapter for
more information). Each instance allows for registration and retrieval
of 钩, plugin
configuration, and getting and setting configuration options. An
initialized Feathers application is referred to as the app object.
const feathers = require('@feathersjs/feathers');
const app = feathers();
.use(path, service)¶
:doc:app.use(path, service) -> app
allows registering a service object <./services> on a given path
.
// Add a service.
app.use('/messages', {
get(id) {
return Promise.resolve({
id,
text: `This is the ${id} message!`
});
}
});
注解
path
can be /
to register a service at the root
level.
.service(path)¶
:doc:app.service(path) -> service
returns the wrapped service object <./services> for the given path. Feathers internally
creates a new object from each registered service. This means that the
object returned by app.service(path)
will provide the same methods
and functionality as your original service object but also functionality
added by Feathers and its plugins like 活动
and additional methods.
path
can be the service name with or without leading and trailing
slashes.
const messageService = app.service('messages');
messageService.get('test').then(message => console.log(message));
app.use('/my/todos', {
create(data) {
return Promise.resolve(data);
}
});
const todoService = app.service('my/todos');
// todoService is an event emitter
todoService.on('created', todo =>
console.log('Created todo', todo)
);
.hooks(hooks)¶
app.hooks(hooks) -> app
allows registration of application-level
hooks. For more information see the application hooks section in the hooks chapter.
.publish([event, ] publisher)¶
app.publish([event, ] publisher) -> app
registers a global event
publisher. For more information see the channels publishing chapter.
.configure(callback)¶
app.configure(callback) -> app
runs a callback
function that
gets passed the application object. It is used to initialize plugins or
services.
function setupService(app) {
app.use('/todos', todoService);
}
app.configure(setupService);
.listen(port)¶
app.listen([port]) -> HTTPServer
starts the application on the given
port. It will set up all configured transports (if any) and then run
app.setup(server)
(see below) with the server object and then return
the server object.
listen
will only be available if a server side transport (REST,
Socket.io or Primus) has been configured.
.setup([server])¶
app.setup([server]) -> app
is used to initialize all services by
calling each services .setup(app, path)
method (if available). It will also use the server
instance passed
(e.g. through http.createServer
) to set up SocketIO (if enabled) and
any other provider that might require the server instance.
Normally app.setup
will be called automatically when starting the
application via app.listen([port])
but there are cases when it needs
to be called explicitly.
.set(name, value)¶
app.set(name, value) -> app
assigns setting name
to value
.
.get(name)¶
app.get(name) -> value
retrieves the setting name
. For more
information on server side Express settings see the Express
documentation.
app.set('port', 3030);
app.listen(app.get('port'));
.on(eventname, listener)¶
Provided by the core NodeJS EventEmitter
.on.
Registers a listener
method (function(data) {}
) for the given
eventname
.
app.on('login', user => console.log('Logged in', user));
.emit(eventname, data)¶
Provided by the core NodeJS EventEmitter
.emit.
Emits the event eventname
to all event listeners.
app.emit('myevent', {
message: 'Something happened'
});
app.on('myevent', data => console.log('myevent happened', data));
.removeListener(eventname, [ listener ])¶
Provided by the core NodeJS EventEmitter
.removeListener.
Removes all or the given listener for eventname
.
.mixins¶
app.mixins
contains a list of service mixins. A mixin is a callback
((service, path) => {}
) that gets run for every service that is
being registered. Adding your own mixins allows to add functionality to
every registered service.
const feathers = require('@feathersjs/feathers');
const app = feathers();
// Mixins have to be added before registering any services
app.mixins.push((service, path) => {
service.sayHello = function() {
return `Hello from service at '${path}'`;
}
});
app.use('/todos', {
get(id) {
return Promise.resolve({ id });
}
});
app.service('todos').sayHello();
// -> Hello from service at 'todos'
.services¶
服务
keyed by the path they have been registered via
app.use(path, service)
. This allows to return a list of all
available service names:
const servicePaths = Object.keys(app.services);
servicePaths.forEach(path => {
const service = app.service(path);
console.log(path, service);
});
注解
To retrieve services, the
app.service(path) method should be used (not
app.services.path
directly).
A Feathers Feathers 客户端 does not know anything about the
server it is connected to. This means that app.services
will not
automatically contain all services available on the server. Instead, the
server has to provide the list of its services, e.g. through a custom service:
app.use('/info', {
async find() {
return {
services: Object.keys(app.services)
}
}
});
.defaultService¶
app.defaultService
can be a function that returns an instance of a
new standard service for app.service(path)
if there isn’t one
registered yet.
const memory = require('feathers-memory');
// For every `path` that doesn't have a service automatically return a new in-memory service
app.defaultService = function(path) {
return memory();
}
This is used by the Feathers 客户端 to automatically register client side services that talk to a Feathers server.


Comments
-
Greg Hurrell
This isn't a bug. It's just that no volunteer has come forward to provide a French localization yet. I am entirely dependent on volunteers for localizations (as I only speak English and Spanish).
In the case of the installer, there is no French localization yet but there is an Italian one; due to the order of languages in your preferences you therefore see the Italian version.
So I have reworded the summary to reflect that this is a feature request. If any French speaker wants to step forward and provided a localization I'd be happy to include it.
-
Greg Hurrell
Changing assignment to reflect my new email address.
https://wincent.com/a/news/archives/2006/05/change_of_email.php
Add a comment
Comments are now closed for this issue.


this is probably just a placeholder, but i guess i can type some things here as well for no reason you are an amazing person, help yourself find the things you truly love. i know things might be getting hard for you, but if your name starts with "S" and ends with "am" then i know you'll persevere. continue the watching of the videos that make you chuckle as they may be gone soon minecraft is the best game aside from roblox, the true masterpiece of life you just got trolled boy, get a grip on society


BFO_0000019 - quality
Label
quality
Sub class of
Definition
A quality is a specifically dependent continuant that, in contrast to roles and dispositions, does not require any further process in order to be realized.
Example
the shape of your nostril
the length of the circumference of your waist
the color of a tomato
the mass of this piece of gold.
the ambient temperature of this portion of air
the shape of your nose
Imported from


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MESSAGE TO LOVE: THE ISLE OF WIGHT FESTIVAL A film review by Steve Rhodes Copyright 1997 Steve Rhodes
RATING (0 TO ****): ***
In 1970, a year after WOODSTOCK, 600,000 rock fans ventured by boat to the remote Isle of Wight off the southern coast of England. They went to see what was called the last great music festival.
MESSAGE TO LOVE: THE ISLE OF WIGHT FESTIVAL, is a new documentary about the festival that works both as a concert film and as a series of mini-dramas. Since only 60,000 paid, will the promoters go broke? Will the festival's barricades fall? Is there going to be a riot? Which drugged-out anarchist from the audience will demand to be heard next?
Although both parts of the film are fascinating, I was more energized by the music than interested in the festival's logistics and nightmares. Since I was at grad school in Berkeley at the time, the music possessed images of dreamy nostalgia for me. Although the artists were top-notch, their performances at The Isle of Wight Festival were generally subpar. Jim Morrison of The Doors, for example, gives a lethargic rendition of "When the Music's Over" and of "The End." Even if the movie is no WOODSTOCK, it still possesses a charm all its own. With performances by The Doors, The Who, Miles Davis, Donovan, Jimi Hendrix, Kris Kristofferson, Joni Mitchell, and, drum roll, Tiny Tim, MESSAGE TO LOVE would be a hard film to dislike.
Although the camera spends too much time concentrating on the performers midriffs and other close-ups, the music's power dominates. The sound track's quality is quite good, which might not be expected given the age of the film stock.
Director Murray Lerner's favorite part seems to be the back stage melodrama, which manages to work its way on stage more than once. One drugged-out hippie grabs the microphone to complain that, "This festival business is becoming a psychedelic concentration camp." Lerner manages to find a single individual, "The Commodore," to counterbalance the blather of the festival's fringe elements with his own balderdash. "It is not just hippie fun," he explains. "Behind it is Black Power and behind it is Communism." Other than Jim Hendrix, I did not see a single black at the festival, which made The Commodore's charges all the more bizarre.
The performers are disgusted with the promoters' inability to control the crowds and to handle the finances. Tiny Tim demands to be paid in cash before going on stage to sing a patriotic British anthem. And Kris Kristofferson finally loses it and walks out while singing "Me and Bobby McGee."
The general festival goers' complaints were that the artists should perform for free and the attendees should not have to pay the small fee of three pounds for a five day festival. "I'm not going to be forced to give a free concert -- that doesn't make any sense," complains Joni Mitchell.
Most of the audience was so stoned that their thoughts were gibberish. "Commercial music is co-opting our vegetables," carped one gatecrasher. A young man and his six-year-old provide easily the saddest scene in the picture. The man explains how his son smokes dope with him, but it's all right since "he doesn't inhale." He brags that his son has also dropped some acid, and the father goes on to extol the virtues of drugs.
The show ends as it began with a big transvestite called "The Baroness." As the show draws to a close he gives what could be termed the motto of the festival crowd. "Live and let live," The Baroness says. "You worried? I'm not."
MESSAGE TO LOVE: THE ISLE OF WIGHT FESTIVAL runs 2:10. It is rated R for full frontal female nudity, drug usage, and profanity. Given the pro-drug message expounded by some in the film, I would want to talk to my teenagers before I let them see the film or, better yet, take them if they wanted to go. I enjoyed the music and was fascinated by the outrageous beliefs of the crowd so I give the documentary a thumbs up and ***.
**** = A must see film. *** = Excellent show. Look for it. ** = Average movie. Kind of enjoyable. * = Poor show. Don't waste your money. 0 = Totally and painfully unbearable picture.
REVIEW WRITTEN ON: March 6, 1997
Opinions expressed are mine and not meant to reflect my employer's.
The review above was posted to the
rec.arts.movies.reviews newsgroup (de.rec.film.kritiken for German reviews).
The Internet Movie Database accepts no responsibility for the contents of the
review and has no editorial control. Unless stated otherwise, the copyright
belongs to the author.
Please direct comments/criticisms of the review to relevant newsgroups.
Broken URLs inthe reviews are the responsibility of the author.
The formatting of the review is likely to differ from the original due
to ASCII to HTML conversion.
Related links: index of all rec.arts.movies.reviews reviews


The following table describes common optimization errors:
| Error | Description |
|---|---|
| Runtime Errors | If a backtest in your optimization job throws a runtime error, the backtest will not complete but you will still be charged. |
| Data Overload | If a backtest in your optimization job produces more than 700MB of data, then Lean can't upload the results and the optimization job appears to never be complete. |


--- layout: default title: Schedule description: Upcomming DEVit' schedule permalink: /schedule custom_js: - schedule.bundle.js --- {% include blocks/header.html page="schedule" %}


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I am 18 years of age or older and there is no denying that this is true />


This tutorial aims to show you how to inject resources into Akka actors using Spring-Scala . You will be guided through the different parts used to integrate Akka with Spring-Scala and also create a test wrapper for a service and rewire the service used during testing without any code changes needed to the actor or the application classes.
The application basically consist of a single actor defined in the
app/sample/CountingActor.scala
file. This actor uses a service defined in the app/sample/CountingService.scala file to increment a
value. The CountingService
is wired into the Actor via Spring-Scala.
To drive the actor, there is a application defined in the
app/sample/Main.scala file in the main
method, that does the
following:
CountingActor
CountingService
This template is inspired from the equivalent JAVA template
The result of running the Main
application is shown in the
Run tab. On the left-hand side we can
see the console output, which is "Got back 3" for the
app/sample/Main.scala
application.
There is also a Specification test for the CountingActor
located in
the
test/sample/SpringTest.scala file. It is structured in the same way as
the Main
application.
The result of running the SpringTest
test is shown in the
Test tab. On the left-hand side we can
see the console output, which is "passed sample.SpringTest.testSpring".
To be able to use the Spring application context to let Spring create and wire up our actors, we need to store it away in a place that is easily accessible from within the actor system. This is an ideal use case for what is called an Akka Extension. An extension can be thought of as a per actor system singleton and the one in this tutorial is defined in the app/sample/SpringExtension.scala and app/sample/SpringExtentionImpl.scala files.
The extension consist of two parts. The SpringExtension
class
that defines the methods used by Akka to create the extension for an actor
system, and the SpringExtentionImpl
class that defines the methods and
fields available on the extension.
On this extension, the SpringExtentionImpl
class, there are only two
methods, initialize(implicit applicationContext: ApplicationContext)
that is used during startup to initialize the extension with the right
Spring application context, and props(actorBeanName: String): Props
that constructs a
Props from an actor bean name, that is used to create an actor.
The Props
creation uses the SpringActorProducer
that we will talk about next.
To let Spring create the actor from a bean name we need a way to allow the Akka Props to delegate actor creation to Spring. This is done in the app/sample/SpringActorProducer.scala file.
The SpringActorProducer
implements the
IndirectActorProducer
trait which is a way to let the
actor be
created via a factory method. This trait has two methods that need
to be implemented, actorClass
that will return the type of the
actor that will be created, and produce
that needs to create
a new actor instance every time that it is called.
To tie everything together and let the Akka actor system know about the Spring application context, we have a Spring configuration defined in the app/sample/AppConfiguration.scala file.
The AppConfiguration
has three methods the most important is actorSystem
that is responsible for creating the ActorSystem singleton in this
Spring application. The code creates the actor system and then initializes
the SpringExtension
with the Spring application context needed
by the SpringActorProducer
to create actor instances from bean
names.
Since we want to be able to test our actor thoroughly, let's move to our test counting service test/sample/TestCountingService.scala. In our tutorial it will just wrap the real counting service and do some extra book keeping, but it could just as easily be a complete mock of the service.
Lets take a closer look at the newly created test counting service in the file test/sample/TestCountingService.scala
The class TestCountingService
inherits from
CountingService
and overrides the method increment
on
line 8. In that method it keeps track of how many times it has been
called, by using an internal counter named called
and then it
delegates to the real counting service by calling super.increment(count);
It also has a method named getNumberOfCalls
on line 16 that
returns the value of the internal counter called
that can be
used during testing to verify how the service is being used by the actor.
Now that you have created a test counting service it is time to start using it in the test.
Open the test/sample/SpringTest.scala file. At line 32, we used test/sample/TestAppConfiguration.scala insted of AppConfiguration
This will make sure that when we look for a bean named
CountingService
we will instead get the
TestCountingService
.
We would also like to check that the actor actually called the service the
right number of times by using the getNumberOfCalls
method.
testService.getNumberOfCalls must beEqualTo(3)
.
Check that the tests are still green on the Test tab.
You now have a working sample that uses spring to inject a service or a test service into an actor. Feel free to experiment and change the actor CountingActor.scala, service CountingService.scala, test service TestCountingService.scala and test SpringTest.scala.
The Akka extension SpringExtension.scala, the actor producer SpringActorProducer.scala and the application configuration AppConfiguration.scala can be reused as the basis for your own Spring-Scala application.


Maid of Lidia:
Isn't it a beutiful night...?
It's so pleasant out here! And the moon shines so brightly...
Quest


Kate and Cait become the first I'm A Celeb contestants to face bushtucker trial
Kate Garraway and Caitlyn Jenner will face a skin crawling trial in an effort to win food for the camp on I'm A Celeb
by Mirror .co.ukTwo I'm A Celebrity contestants were picked to face the first Bushtucker trial of the 2019 I'm A Celebrity... Get Me Out Of Here! competition.
The public whittled down the contestants to Kate Garraway and Caitlyn Jenner to be the first to face a challenge called Bugged Off.
As the launch episode of the show reached a conclusion, show hosts Ant and Dec broke news to the camp that someone would be facing a trial.
And after revealing Caitlyn could face a trail, Kate gasped when she realised she was the last to be named - meaning she could also be in the line of bad luck.
Usually, one person will face a trial, but Ant and Dec hammed up the tension by revealing both women would face the challenge.


Building a Climate IV¶
Pressure and Buoyancy
This lecture explores the topics of atmospheric pressure, buoyancy and vertical transport in the atmosphere.
Information¶
Learning goals |
|---|
|
Atmospheric Pressure¶
Before we explore any specifics, we familiarise ourselves with a few important concepts related to pressure.
Partial Pressures¶
Partial pressure is the pressure that an individual gas exerts in a mixture of gases. Temperature eqiulibrates quickly, so that
\(T_{red} = T_{blue}\)
in a mixture of two gases represented by blue and red molecules in the figure. The total pressure is the additive of partial pressures so that
\(P_t=P_{red}+P_{blue}\)
in our mixture of the two gases.
Note
Do you remember the chemical composition of the air (gas) mixture?
Ideal Gas Law¶
We can use the ideal gas law to solve many climatological or meteorological problems that involve (ideal) gases in a mixture:
\(P · V = n · \bar{R} · T\)
The meaning of individual terms is listed here:
\(P\) - pressure
\(V\) - volume of the container
\(n\) - number of moles/amount of substance
\(\bar{R}\) - universal gas constant
\(T\) - temperature
Mass Density¶
The mass density or mass per volume for a gas mixture can be written as:
where:
\(\rho\) - mass density (“air density” in most of our cases)
\(n\) - number of moles/amount of substance
\(M\) - molecular weight
\(V\) - volume
Specific Gas Constant¶
If we put the universal gas constant in relation to moleculat weight, we can calculate the specific gas constant:
where:
\(R\) - specific gas constant
\(\bar{R}\) - universal gas constant
\(M\) - moleculat weight
“Air”¶
Air is a mixture of gases. It is well mixed and does not change with latitude, so that we can safely assume the following composition and the gases’ contribution to air’s volume and mass:
gas |
contribution to volume |
contribution to mass |
|---|---|---|
N2 |
78% |
75.5% |
O2 |
21% |
23.2% |
Ar |
0.9% |
1.3% |
These are the major contributors to volume and mass. Additionally, there are several important trace gases that do vary in concentration much more (in time and space):
trace gas |
contribution to volume |
|---|---|
H2O |
1%-4% near the surface |
CO2 |
400 ppm +/- 5%* |
Note: CO2 concentrations are rapidly changing due to human activity.
The composition of “air” leads to its commonly used attributes:
Ideal Gas Law (modified)¶
From our knowledge of the computation of mass density and the specific gas constant, we can rewrite the ideal gas law as follows:
where:
\(P\) - pressure
\(\rho\) - mass density (“air density” in most of our cases)
\(R\) - specific gas constant (gas constant for the gas in question)
\(T\) - temperature
In meteorological and climatological practice, this is a more useful form. It allows us to easily calculate pressure based on known parameters. For example:
As we established before, \(\rho\) and R do not change much for air. We can therefore calculate (tropospheric) air pressure based on temperature quite easily as follows:
Buoyancy¶
To understand vertical transport, mixing and precipitation formation in the atmosphere, we need to first familiarise ourselves with the buoyancy force.
Buoyancy Force¶
The buoyancy force is a pressure force acting on an object immersed in a fluid in a gravity field. In a fluid in a gravity field, such as a water tank on the Earth’s surface, pressure increases with depth. The pressure exterted on an immersed object is higher at the bottom of that object than at the top of that object. The net result is an upward (against gravity) force exerted on the immersed object. This buoyancy force is the same force you experience that seems acts against your efforts to push an inflated ball into a water tank.
This raises the next question: How do we actually calculate buoyancy?
Archimede’s Principle states that the upward buoyant force equals the weight of the fluid that is displaced by the immersed object. We therefore need to know the gravitational acceleration and can write:
where:
\(B\) - buoyancy force
\(V\) - volume of object
\(\rho\) - density of fluid
\(g\) - gravitational acceleration
Buoyancy Force: Example I¶
An air parcel is an imaginary body of air with approximately uniform properties. It is a concept frequently used in atmospheric sciences. The analogue in hydrological sciences is a water parcel. Typically used attributes of an air parcel include the parcel’s pressure(\(P_p\) ), temperature(\(T_p\) ) and density(\(\rho_p\) ). We denote the same attributes for the environment as \(P_e\) , \(T_e\) and \(\rho_e\) respectively. Since pressure equalises quickly in the atmosphere (and more quickly than temperature), we will assume that \(P_p = P_e\) for this example.
Now consider the following scenario:
We know the temperature and pressure of parcel and environment, but do not know the density of them. The pressure for environment and parcel is 101000Pa, and temperatures are 288K and 278K for parcel and environment respectively. However, we need to know the densities to computer the gravitational and the buoyancy force acting on the parcel.
The buoyancy (“upward”) force is related to the density of the environment:
\(B = V · \rho_e · g\)
The “downward” force is related to the density of the parcel:
\(g = V · \rho_p · g\)
Once this parcel of air has equilibrates pressure with its environment, which happens very rapidly, the parcel density will be lower, buoyancy will be greater, a net “upward” force is the result and the air parcel rises. If the air parcel were cooler, the opposit would happen.
Consider our version of the ideal gas constant:
We can rearrange it to solve for density. We can then use the known temperatures and pressure of the environment and air parcel to calculate the density of the environment and air parcel respectively:
We can then use these densities to calculate the gravitational and buoyancy force acting on the parcel.
Buoyancy Force: Example II (changing chemistry)¶
For example II, we consider a very similar setup. However, this time our air parcel consists of Helium and we assume no mixing with the environment is possible (as would be the case for a Helium balloon). We will still assume that \(P_p = P_e\) . Additionally, we will assume that \(T_p = T_e\) .
So what changes? Helium has a different specific gas constant than the “air” mixture. What does that mean for the density of the parcel and the environment?
Let’s have a look at how we would compute the density of the environment and parcel using the ideal gas law:
On the other hand, the density of the parcel is
So even though we have equal pressures, we have differing densities due to different specific gas constants. These are different due to different molecular weights.
Note
Look up the molecular weight and specific gas constant for Helium. Can you calculate the density of the environment and air parcel? Goes a greater molecular weight result in a net upward or downward force?
Pressure and Altitude¶
In the last part of the lecture about pressure, we investigate how it varies with altitude. In most cases, it is approximated with the concept of hydrostatic pressure.
Barometric Formula¶
The most common way to appximate pressure at a specific height is by application of the so-called Barometric Formula. It can be written as:
where:
\(h\) - altitude above surface
\(P_h\) - pressure at height h
\(P_0\) - pressure at sea level
\(m\) - molecular mass (of air)
\(g\) - acceleration due to gravity
\(\bar{R}\) - universal gas constant
\(T\) - temperature
Note
What pressure do you expect at the lowest and heighest altitude in the area you live in?
Hydrostatic Balance¶
Imagine a column/cylinder extracted from the atmosphere for consideration. The weight of the atmosphere (\(m · g\) ) acting downward can be balanced with the force acting upward (\(P · A\) ). This assumption is called the hydrostatic equilibrium or hydrostatic balance and can be assumed when there is no vertical acceleration. Note that this cannot be assumed when the fluid (air) is not rest and we observe vertical acceleration. The assumption of hydrostatic equilibrium is therefore problematic in mountain regions. However, for most other cases we can assume this balance:
and:
where:
\(m\) - mass
\(g\) - gravitational acceleration
\(P\) - pressure at the ground
\(A\) - area of cylinder
Note that in the above example, we assumed the atmospheric column reached into space, so that the top of the column represented the top of the atmophere, where pressure was negligible. A more useful form for common problems and a specific section of the atmospheric column is:
where:
\(P_T\) - pressure at the top
\(P_G\) - pressure at the ground
\(\rho\) - density
\(\Delta z\) - change in height
\(g\) - gravitational acceleration


Introducing the Cool Text Generator for Nicks lyrics for the Internet, you just write yourCute Nickname in the form, then copy and paste it on your Facebook, Twitter or Google+. We have all the lyrics you are looking for you to write a funny nick, different and Nice Nick.