Tiaher, T PhD thesis, "Application of Spectrum Observatory Measurements to Support Traffic Model-based Dynamic Spectrum Access," completed for the Electrical and Computer Engineering Department at the Illinois Institute of Technology, July 2014.
R. Attard, J. Kalliovaara, T. Taher, J. Taylor, D. Roberson, J. Paavola, and R. Ekman, "A High-performance Tiered Storage System for a Global Spectrum Observatory Network," presented at the Wireless Finland US (WiFiUS) special session conference, held at Oulu, Finland in June 2014.
Hoyhta, M, Matinmikko, M, Chen, X, Hallio, J, Roning, J, Riaz, A, Taher, T, Roberson, D, Kalliovaara, J, "Measurements and Analysis of Spectrum Occupancy in the 2.3-2.4 GHz band in Finland and Chicago," presented at EAI Crowncom 2014 conference, held at Oulu, Finland.
Taher, Tanim, Attard, Ryan, Riaz, Ali, Roberson, Dennis, Taylor, Jesse, Zdunek, Kenneth, Hallio, Juhani, Ekman, Reijo, Paavola, Jarkko, Suutala, Jaakko, Roning, Juha, Matinmikko, Marja, Hoyhtya, Marko, MacKenzie, Allen, "Global spectrum observatory network setup and initial findings," Cognitive Radio Oriented Wireless Networks and Communications (CROWNCOM), 2014 9th International Conference on, pp.79,88, 2-4 June 2014.
Matinmikko, M., Mustonen, M., Roberson, D., Paavola, J., Höyhtya, M., Yrjola, S., Roning, J., "Overview and comparison of recent spectrum sharing approaches in regulation and research: From opportunistic unlicensed access towards licensed shared access," Dynamic Spectrum Access Networks (DYSPAN), 2014 IEEE International Symposium on, pp.92,102, 1-4 April 2014 doi: 10.1109/DySPAN.2014.6817783.
Taher, T., Zdunek, K., Roberson, D., "Statistical modeling framework of live spectrum observation data for opportunistic spectrum sharing," Cognitive Radio Oriented Wireless Networks (CROWNCOM), 2013 8th International Conference on, pp.1,6, 8-10 July 2013 doi: 10.1109/CROWNCom.2013.6636785.
Taher, T., Zdunek, K., Roberson, D., "Statistical modeling framework of live spectrum observation data for opportunistic spectrum sharing," Cognitive Radio Oriented Wireless Networks (CROWNCOM), 2013 8th International Conference on, pp.1,6, 8-10 July 2013 doi: 10.1109/CROWNCom.2013.6636785.
G. Noorts, J. Engel, J. Taylor, D. Roberson, R. Bacchus, T. Taher, K. Zdunek, "An RF Spectrum Observatory Database based on a Hybrid Storage System," 2012 IEEE Conference on Dynamic Spectrum Access Networks, DySPAN 2012, Bellevue, Washington, October 2012.
T. Taher, R. Bacchus, K. Zdunek, D. Roberson, "Empirical Modeling of Public Safety Voice Traffic in the Land Mobile Radio Band," 2012 Conference on Cognitive Radio Oriented Networks and Communications, (CROWNCOM, 2012), Stockholm, Sweden. Link
Taher, T PhD thesis, "Application of Spectrum Observatory Measurements to Support Traffic Model-based Dynamic Spectrum Access," completed for the Electrical and Computer Engineering Department at the Illinois Institute of Technology, July 2014.
R. Attard, J. Kalliovaara, T. Taher, J. Taylor, D. Roberson, J. Paavola, and R. Ekman, "A High-performance Tiered Storage System for a Global Spectrum Observatory Network," presented at the Wireless Finland US (WiFiUS) special session conference, held at Oulu, Finland in June 2014.
Hoyhta, M, Matinmikko, M, Chen, X, Hallio, J, Roning, J, Riaz, A, Taher, T, Roberson, D, Kalliovaara, J, "Measurements and Analysis of Spectrum Occupancy in the 2.3-2.4 GHz band in Finland and Chicago," presented at EAI Crowncom 2014 conference, held at Oulu, Finland.
Taher, Tanim, Attard, Ryan, Riaz, Ali, Roberson, Dennis, Taylor, Jesse, Zdunek, Kenneth, Hallio, Juhani, Ekman, Reijo, Paavola, Jarkko, Suutala, Jaakko, Roning, Juha, Matinmikko, Marja, Hoyhtya, Marko, MacKenzie, Allen, "Global spectrum observatory network setup and initial findings," Cognitive Radio Oriented Wireless Networks and Communications (CROWNCOM), 2014 9th International Conference on, pp.79,88, 2-4 June 2014.
Matinmikko, M., Mustonen, M., Roberson, D., Paavola, J., Höyhtya, M., Yrjola, S., Roning, J., "Overview and comparison of recent spectrum sharing approaches in regulation and research: From opportunistic unlicensed access towards licensed shared access," Dynamic Spectrum Access Networks (DYSPAN), 2014 IEEE International Symposium on, pp.92,102, 1-4 April 2014 doi: 10.1109/DySPAN.2014.6817783.
Taher, T., Zdunek, K., Roberson, D., "Statistical modeling framework of live spectrum observation data for opportunistic spectrum sharing," Cognitive Radio Oriented Wireless Networks (CROWNCOM), 2013 8th International Conference on, pp.1,6, 8-10 July 2013 doi: 10.1109/CROWNCom.2013.6636785.
G. Noorts, J. Engel, J. Taylor, D. Roberson, R. Bacchus, T. Taher, K. Zdunek, "An RF Spectrum Observatory Database based on a Hybrid Storage System," 2012 IEEE Conference on Dynamic Spectrum Access Networks, DySPAN 2012, Bellevue, Washington, October 2012.
T. Taher, R. Bacchus, K. Zdunek, D. Roberson, "Empirical Modeling of Public Safety Voice Traffic in the Land Mobile Radio Band," 2012 Conference on Cognitive Radio Oriented Networks and Communications, (CROWNCOM, 2012), Stockholm, Sweden. Link
Dennis Roberson, "Radio Receiver Basics," FCC Workshop on Spectrum Efficiency and Receivers (Day 2, Session 2) March 13, 2012, www.fcc.gov/workshops
Dennis Roberson, "The Case for Receivers Standards and Regulations," FCC Workshop on Spectrum Efficiency and Receivers (Day 2, Session 6) March 13, 2012, www.fcc.gov/workshops
"Priority Access for Public Safety on Shared Commercial Networks," Suresh Borkar, K. Zdunek, and Dennis Roberson, Telecom World (ITU WT), 2011 Technical Symposium at ITU, 24-27 Oct. 2011.
J. Taylor, D. Roberson, "A Geographic Comparison of 802.11 Wireless Access Point Usage," 21st Symposium for Undergraduates in Science, Engineering and Mathematics, Argonne National Laboratory, Argonne, IL, October 2011.
"National Broadband Network for Public Safety: Priority Management," Suresh Borkar, Kenneth Zdunek, and Dennis Roberson, IIT Real-Time Communication Conference, Oct 11, 2011.
"Nationwide Broadband Priority Access Network for Public Safety," Ken Zdunek, Suresh Borkar, and Dennis Roberson, 2011 Oklahoma Public Safety Conference, Tulsa, OK, October 2011.
T. Taher, R. Bacchus, K. Zdunek, D. Roberson, "Dynamic Spectrum Access Opportunities for Public Safety in Land Mobile Radio Bands," 2011 Conference on Cognitive Radio Oriented Networks and Communications, (CROWNCOM, 2011), Osaka, Japan. Link
T. Taher, R. Bacchus, K. Zdunek, D. Roberson, "Long-term Spectral Occupancy Findings in Chicago," 2011 IEEE Conference on Dynamic Spectrum Access Networks (DYSPAN 2011), Aachen, Germany. Link
R. Bacchus, T. Taher, K. Zdunek, D. Roberson, "Spectrum Utilization Study in Support of Dynamic Spectrum Access for Public Safety," 2010 Conference on Dynamic Spectrum Access, DYSPAN 2010, April 2010. Link
K. Rele, L. Li, B. Zhang, T. Taher, D. Roberson, Y. Yap, K. Zdunek, 'A Two-Tiered Cognitive Radio System for Interference Identification in 2.4 GHz ISM band," accepted in IEEE Consumer Communications and Networking Conference (CCNC), Las Vegas, January 2010. Link
A.Z. Al-Banna, 'Interference in IEEE 802.11 WLANS,' Publisher: Vdm Verlag Dr Mueller E K, 2009. ISBN-10:<PHONE_NUMBER>.
R.B. Bacchus, "Implementation of a Long-Term, Wideband, Spectrum Observatory," MSEE Thesis, Illinois Institute of Technology, Chicago, IL, July, 2009.
J. Dzikowski, C. Hood, 'An agent-based simulation framework for cognitive radio studies,' Proceedings of the 2nd International Conference on Simulation Tools and Techniques, Rome, Italy, March 02 - 06, 2009. Link
T.M. Taher, K. Rele, D. Roberson, "Development and Quantitative Analysis of an Adaptive Scheme for Bluetooth and Wi-Fi Co-Existence,' IEEE Consumer Communications and Networking Conference (CCNC), Las Vegas, January 2009. Link
D.A. Roberson, 'Chapter Three,' in Cognitive Radio Communications and Networks: Principles and Practice, A. Wyglinski, M. Nekovee, and T. Hou, (Dec 2009). Publisher: Elsevier. ISBN-13: 978-0-12-374715-0.
Y. Yap, L. Li, B. Zhang, K. Rele, "Quantitative Analysis of Wi-Fi in the Presence of Interferers, "IEEE Consumer Communications and Networking Conference (CCNC), Las Vegas, January 2009. Link
A. Carfang, M. Zaturensky, J. Lloyd, D. Roberson, 'Wireless In Motion: Ad Hoc Network Performance of Wi-Fi and Bluetooth in Mobile Environments', IEEE 2nd International Workshop on Mobile Vehicular Networks, MoVeNet 2008, Atlanta, GA, September 2008. Link
U. Das, C.S. Hood, "Using a Shielded Room to Characterize UDP performance in the presence of Interference in IEEE 802.11 Wireless Networks,' IEEE Conference on Dynamic Spectrum Allocation, DySPAN08, Chicago, IL, October 2008. Link
R. B. Bacchus, A. J. Fertner, C. S. Hood and D. A. Roberson, "Long-term, wideband spectral monitoring in support of Dynamic Spectrum Access Networks at the IIT Spectrum Observatory," IEEE Conference on Dynamic Spectrum Allocation, DySPAN'08, Chicago, IL, October 2008. Link
T.M. Taher, M.J. Misurac, J.L. LoCicero, and D.R. Ucci, "Microwave Oven Signal Interference Mitigation For Wi-Fi Communication Systems," 5th IEEE Consumer Communications and Networking Conference, 2008, CCNC 2008. pp.67-68, 10-12 Jan. 2008. Link
T.M. Taher, M.J. Misurac, J.L. LoCicero, and D.R. Ucci, "Microwave Oven Signal Modeling," Wireless Communications and Networking Conference, 2008, WCNC 2008, pp.1235-1238, March 31 2008-April 3 2008. Link
A.Z. Al-Banna, J.L. LoCicero, D.R. Ucci, "Multi-element adaptive arrays for interference mitigation of multiple barker/CCK signals in 802.11b WLANs," Sarnoff Symposium, 2007 IEEE, pp.1-5, April 30 2007-May 2 2007. Link
A.Z. Al-Banna, X. Zhou, T.R. Lee, J.L. LoCicero, and D.R. Ucci, "Interference Characterization and Mitigation of 5.5 Mbps CCK WI-FI Signals," Electromagnetic Compatibility, 2007. EMC 2007. IEEE International Symposium on, pp.1-8, 9-13 July 2007. Link
A.Z. Al-Banna, J.L. LoCicero, and D.R. Ucci, "Multi-Element Adaptive Arrays with Tapped Delay Lines for Interference Mitigation in IEEE 802.11G OFDM Systems," Military Communications Conference, 2007. MILCOM 2007, pp.1-8, 29-31 Oct. 2007 Link
J.T. MacDonald, U. Das, D.A. Roberson, 'Client Channel Selection for Optimal Capacity in IEEE 802.11 Radio Channels,' presented at the IEEE Conference on Dynamic Spectrum Allocation, DySPAN'07, April 2007, Dublin, Ireland.
J. MacDonald, D. Ucci, 'Interference Temperature Limits of IEEE 802.11 Protocol Radio Channels,' IEEE Electro/Information Technology Conference, Chicago, Illinois, May 2007. Link
J. MacDonald, D. Roberson, 'Spectrum Occupancy Estimation in Wireless Channels with Asymmetric Transmitter Powers,' Second International Conference on Cognitive Radio Oriented Wireless Networks and Communications (CrownCom), Orlando, Florida, August 2007. Link
D.A. Roberson, 'Structural Support for Cognitive Radio Deployment,' Invited paper, in Second International Conference on Cognitive Radio Oriented Wireless Networks and Communications, August 2007.
T.M. Taher, M. Misurac, D. Ucci, J. LoCicero, 'Symbol Shaping for Barker Spread Wi-Fi Communications,' IEEE Electro Information Technology Conference, Chicago, Illinois, May 2007. Link
D.A. Roberson, 'Chapter 11: Cognitive Radio,' in Wireless Communications - The Future," W.Webb (2007). Publisher: John Wiley & Sons. ISBN 978-0-03312-8 (HB).
A.Z. Al-Banna, T. Lee, J.L. LoCicero, and D.R. Ucci, '11 Mbps CCK-Modulated 802.11b Wi-Fi: Spectral Signature and Interference,' in Proc. Sixth IEEE International Conf. on Electro/Information Technology, EIT'06, May 2006. Link
A.Z. Al-Banna, J.L. LoCicero, and D.R. Ucci, 'Effect of Cyclic Prefix and Symbol Shaping on Inter-Carrier and Inter-Channel Interference in OFDM Systems,' in Proc. World Wireless Congress, WWC'06, May 2006.
A.Z. Al-Banna, J.L. LoCicero, and D.R. Ucci, 'Adaptive Antennas for Interference Mitigation of Barker/CCK Spread Wi-Fi Signals,' in Proc. 2nd IEEE Intl. Wkshp Perf. Mgt. Wireless Mobile Networks, Nov. 2006. Link
A.Z. Al-Banna, J.L. LoCicero, and D.R. Ucci, 'Interference Mitigation in IEEE 802.11g OFDM Systems with Smart Antennas and Tapped Delay Lines,' in Proc. IEEE Military Communications Conference, Oct. 2006. Link
D.A. Roberson, C.S. Hood, J.L. LoCicero, and J.T. MacDonald, "Spectral Occupancy and Interference Studies in Support of Cognitive Radio Technology Deployment," in Proceedings of the First IEEE Workshop on Net. Tech. For SDR Networks, Reston, VA, Sept. 2006.
C.S. Hood and D.A. Roberson, 'Guest Editorial: Management of Interference in Wireless Networks,' International Journal of Network Management, vol. 16, no. 2, pp. 85-87, March-April, 2006.
M.A. McHenry, P.A. Tenhula, D. McCloskey, D.A. Roberson, and C.S. Hood, 'Chicago Spectrum Occupancy Measurements & Analysis and a Long-term Studies Proposal,' in Proceedings of First International Workshop on Technology and Policy for Accessing Spectrum, TAPAS'06, Boston, MA, August 2006.
T.M. Taher, A.Z. Al-Banna, J.L. LoCicero, and D.R. Ucci, 'Characteristics of an Unintentional Wi-Fi Interference Device – The Residential Microwave Oven,' in Proc. IEEE Military Communications Conference, Oct. 2006. Link
J.T. MacDonald, D.A. Roberson, and D.R. Ucci, 'Location Estimation of Isotropic Transmitters in Wireless Sensor Networks,' in Proc. IEEE Military Communications Conference, Oct. 2006. Link
X. Zhou, 'Spectral Signature and Interference of Wi-Fi Signals in the 2.4 GHz ISM Band,' MS Thesis, ECE Department, Illinois Institute of Technology, Chicago, IL.
M.A. McHenry, D. McCloskey, D.A. Roberson and J.T. MacDonald, "Spectrum Occupancy Measurements, Chicago, Illinois, November 16-18 2005," Shared Spectrum Company Report, Dec. 2005.
T. Lee, A.Z. Al-Banna, X.L. Zhou, J.L. LoCicero, and D.R. Ucci, 'Spectral Signatures and Interference of 802.11 Wi-Fi Signals with Barker Code Spreading,' in Proc. IEEE Dynamic Spectrum. Access Networks Conference, DySPAN'05, November 2005. Link


This test-case is intended for Issue #3597
- Objects turned into string have their DOM panel representation messed up.
Jan Odvarko<EMAIL_ADDRESS>Execute Test
button below._testString
changes from object to string and so,
it shouldn't display any children and should not be expandable any more.


Cloud computing is a very
large term that means little to the users. It basically means “the delivery of
on-demand computing services”. Cloud computing covers a wide range of services
including application design, online storage space to processing power, often
through the internet.
How exactly does cloud computing compete with other
technologies? Think of cloud computing as a warehouse renting service. Instead
of packing everything in your house, which sometimes mean that you run out of
space or cannot fit large objects (large data or services in case of companies),
you can rent these “warehouses” to store your information and data. This simile
means that without spending to set up your own IT infrastructure, individuals,
organizations and companies can save costs by renting from cloud computing
services.
With that in mind, we can see how cloud computing is on the rise
with exponential popularity. Virtually any service now has global or at least
regional markets and clienteles that require fast and spontaneous services.
Therefore, any service that does not require their customer base to have IT
infrastructure can pay for cloud computing services in order to distribute
their products or data storage.
Cloud
computing comes from the “location” of all the software and hardware or
relevant information of users put together in a “cloud” shape, denoting that it
is not necessary to pinpoint where all of these data are located on any
specific IT infrastructure. Instead, the oversimplified term “cloud”
encompasses all of the data like a border.
Cloud Computing Service Models
Cloud Computing can be categorized as
three different service models: Infrastructure-as-a-Service (IaaS),
Platform-as-a-Service (PaaS) and Software-as-a-Service (SaaS). What is the
difference between the three models? IaaS, as the name suggests, rent out IT
cloud infrastructure as a service. The clientele of IaaS are usually companies
or organizations that want to build their applications or products from scratch
and control any associating elements from the get-go. Controlling and
maintaining IT infrastructure for Cloud computing can help with this. On the
other hand, PaaS offers tools and software required to build the applications
the developers need, on top of providing storage, networking, and virtual
servers. Finally, the most common service model, the IaaS. offers the finished
products as interfaces or software that users or clients can access via web
browsers or applications. The hardware or infrastructure that support the
interface or products are irrelevant to the users and clients in the case of
IaaS.
Cloud computing’s increase in
popularity means that it is racking in monumental revenue for the IT world.
Below is an image of the revenue of Cloud computing as a service in billions
from 2016 to projected first quarter 2021, courtesy of zdnet.com:


Our mission is to provide a realistic view of campus life through a network of trustworthy students. We believe that only through a full day of interaction with current students of similar interests will high schoolers truly be able to narrow down their prospect colleges.


About our Project team member
Home
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TEAM ROLES
Vick Javariz
BACK-END
Chad Simpson
REACT-I
Robert Murdoch
REACT-II
Nicole Osborn
WEB UI
Khwanchai Phaipha


jQuery Mobile adds classes to the HTML
element that mimic browser orientation and common min/max-width CSS media queries. These classes are updated on load, resize and orientationchange, allowing you to key off these classes in your CSS, to create responsive layouts - even in browsers that don't support media queries!
The HTML element will always have a class of either "portrait"
or "landscape"
, depending on the orientation of the browser or device. You can utilize these in your CSS like this:
.portrait {
/* portrait orientation changes go here! */
}
.landscape {
/* landscape orientation changes go here! */
}
By default, we create min and max breakpoint classes at the following widths: 320
,480
,768
,1024
. These translate to classes that look like this: "min-width-320px"
, "max-width-480px"
, and are meant to be used as a replacement of (or in addition to) the media query equivalents they mimic.
.myelement {
float: none;
}
.min-width-480px .myelement {
float: left;
}
Many plugins in jQuery Mobile leverage these width breakpoints. For example, form elements float beside their labels when the browser is wider than 480 pixels. The CSS to support this behavior for form text inputs looks like this:
label.ui-input-text {
display: block;
}
.min-width-480px label.ui-input-text {
display: inline-block;
}
To utilize width breakpoints of your own, jQuery Mobile exposes the $.mobile.addResolutionBreakpoints
function, which accepts either a single number or array of numbers that will be added to the min/max breakpoints whenever they apply.
//add a min/max class for 1200 pixel widths
$.mobile.addResolutionBreakpoints(1200);
//add min/max classes for 1200, and 1440 pixel widths
$.mobile.addResolutionBreakpoints([1200, 1440]);
jQuery Mobile provides a function that allows you to test whether a particular CSS Media Query applies. Simple call $.mobile.media()
and pass a media type or query. If the browser supports that type or query, and it currently applies, the function will return true. If not, it'll return false.
//test for screen media type
$.mobile.media("screen");
//test a min-width media query
$.mobile.media("screen and (min-width: 480px)");
//test for iOS retina display
$.mobile.media("screen and (-webkit-min-device-pixel-ratio: 2)");


--- layout: post title: Bookmarks for January 25th from 22:15 to 23:50 tags: - backbone.js - bdd - checkbox - css - css3 - decorator - design - ember.js - framework - iphone - jasmine - javascript - jquery - led - mobile - mvc - mvp - node.js - patterns - review - series - synchronised browsing - tumble - tutorial status: publish type: post published: true meta: aktt_notify_twitter: 'no' ---
These are my links for January 25th from 22:15 to 23:50:


Mempool Analysis & Simulation (2019-06-08)
Transcript By: Bryan Bishop
Tags: Mempool
Category: Conference
Mempool analysis and simulation
kallewoof
Date: 2019-06-08
https://twitter.com/kanzure/status/1137342023063744512
video: https://www.youtube.com/watch?v=Mznn1uVyTUQ
slides: https://breaking-bitcoin.com/docs/slides/2019/mempoolAnalysis.pdf
Introduction
Fun fact: I don’t think anyone knows this fact, but antpool is a miner and antpool is not mining replace-by-fee transactions. What I mean by that is that if you do a replace-by-fee transaction, they will ignore the second high fee transaction. There are cases where transactions are RBF-bumped to increase the fee to make it mined faster, so you RBF bump it, and then you have people spending the unconfirmed RBF version and then have a chain of transactions but then the original transaction is mined and not the other chained transactions. So that’s interesting.
I am going to talk about simulating the mempool and how that is useful and also analysis techniques.
Agenda
It’s very simple: I am going to start with why, then what, and how I did that, and then so what.
Why mempool analysis
Back a few years ago, I was doing a presentation on scaling stuff where I was saying we could use the mempool to get better estimation of fee rates. After I went off to implement that, I realized that wait I don’t actually have a good way to compare parameters to figure out what is the optimal way to do this. You don’t want to have something where you have a transaction that never gets confirmed and you have to keep RBF bumping it… we want some kind of analysis for fee estimation reasons. Originally I had patched Bitcoin Core to in real-time look at the mempool. To get one day worth of data, you would have to wait one day which was not very fast.
Another thing is that right now we’re losing data. We only know when a transaction was mined, not when it appeared. We don’t know much about transactions that were invalidated, when a second transaction replaces the first one there’s often no way to find the original transaction. I wanted a way to record the mempool and be able to play back that recording and to be able to do various analysis on that.
Why record and playback the mempool?
Ther’s a loss of information like timestamps, blocks and transactions. There’s no good answer to “what happened at time x”. We don’t know, was the mempool full? How many transactions were circulating at that time? If a transaction wasn’t mined, then when did it get out of the mempool? When the mempool gets full, it starts pushing transactions out. This could be useful for fee estimation as well, but there’s no recordings of that. Having a tool to help store mempool data would help us see what information we can get out of that. Also questions like is it spam or not spam? What portions of transactions are mined by miners? Without this tool, we don’t know that. We could make statements about which transactions we knew about or didn’t know about, and which ones miners introduced before we knew them.
There’s a tool called MFF that helps do this.
A new tool for mempool analysis
Mempool File Format helps logs time of re-entry, exit, confirmation and invalidation. You can always get transaction data out of the log. When the block is mined, it stores the block. When a block is unmined, the tool points this out and says it was no longer there. You can seek through this log file on a block by block basis or by blockheight. If you want to find transaction X that is an O(n) operation and it’s not very optimal. This is a very specific kind of format, which solves a specific task and it’s very bad in most other cases.
There’s a library implementation of this as well called libbcq, which was built on top of a database format called CDBQ.
Light clients download blocks and store nothing. You have pruned full nodes which download all blocks and recent transactions, and keep recent confirmed blocks and unconfirmed transactions. Full nodes store all confirmed blocks and unconfirmed transactions. With MFF enabled, all blocks and recent transactions are downloaded, and all blocks, unconfirmed + invalidated transactions are preserved while also retaining the order in which they appeared. Note that in pruned nodes and full nodes, we lose information about unconfirmed transactions that disappear or never get into the blockchain.
MFF so far
I have a bunch of zeromq dumps. It stores it to a big text file. I have a tiny mempool example and a bigger mempool. Creating these from zeromq dumps takes a long time. In my bigger mempool zeromq dump, it takes about 15 MB/day to store all of this data including all the blocks and all the transactions. There’s about 31.8 million entries, and 55,101 invalidated transactions.
It’s Bitcoin Core with MFF enabled. If we ever hit another mempool explosion, we will be able to see much better how did things behave and how can we do things to alleviate those problems whether from Bitcoin Core or other wallets. If you have a smaller mempool, you get more data, and that’s simply because it has to start throwing things out.
CQDB
CQDB is a funny way of saying “sequential database”. It’s a database, it’s a seekable sequential database, both a library and spec. Then there’s BCQ which is bitcoin CQ (specialization of CQ for bitcoin). There’s also a Bitcoin Core patch and hopefully more in the future.
CQDB is a light-weight, space and memory efficient sequential database. It’s append-only. It is restricted to chronological order. A tricky thing here is that when you store this data, it’s just written once and then it’s never changed again. In order to keep some kind of reference to the inside of a cluster like where is block X you have to have a header and the header is written into the next cluster here. Clusters are stored as blocks of header+data pairs.
You serialize objects once, then use references to point back at their byte position. The reader does not have to have any data in memory. If you only have room for ten transactions, then you could throw everything else out and keep 10. When you want to learn about another transaction beyond those 10, you can go back and read the data by looking at the reference for where to seek to.
BCQ
BCQ is a CQDB where each segment corresponds to a block in the blockchain. Objects in this case are transactions. Say you write a transaction into cluster 3, starting at byte position 10000. You write that in. Later when you want to reference it, like in block 30000, then you say yeah transaction 10000 written as a varint it’s actually not a varint.. then if you don’t know this transaction then you can take the bytes and seek back 20000 bytes and go to the transaction and deserialize the transaction there. It also writes the segment input information into the header so you can seek to that segment if you wanted to.
https://github.com/kallewoof/bitcoin/tree/libbcq
btc.com output splitting transaction
This transaction looks weird to me. All the inputs are from outputs with the same scriptpubkey, and all the outputs have the same scriptpubkey. I asked them what they were doing, and btc.com said they were splitting outputs for faster payous. They are doing this because if they don’t do this, they run out of outputs for paying users. This still doesn’t explain why you would have a bunch of inputs on the same transaction, but that’s what they are saying anyway…
What is it good for?
It’s good for education to learn how bitcoin works, see the flow of a transaction being fee-bumped or RBF-bumped. It’s useful for scientific purposes, like writing better algorithms for fee estimation and things like that.


iPhone XS captures rocket blastoff, proving there's life in the old dog yet
Source: iMore
What you need to know
- Photographer John Kraus took a photo of a rocket using his iPhone XS Max.
- The rocket was a SpaceX CRS-19.
- The photo looks better than a phone has any right to produce.
In the tech world we're all guilty of chasing the latest, hottest, flashiest, and fastest thing. This year that's iPhone 11, iPhone 11 Pro, and iPhone 11 Pro Max. But that's unfair to iPhone XS and iPhone XS Max. Until 2019, they were the best iPhones ever made. And photographer John Kraus has reminded us (via 512Pixels) just how good their cameras are, too.
Kraus took his iPhone XS Max and placed it near the launch site of SpaceX's CRS-19 rocket. The result is a shot that looks highly impressive and reminds us once again that perhaps we don't really need the latest iPhone in order to take some amazing shots.
Save 40% and get three months of wireless service for just $45
Now admittedly this isn't going to make me trade my iPhone 11 Pro in for a used iPhone XS. But if you're still on the fence about upgrading, this might make you think twice. Especially if you've been happy with your iPhone XS and its photography prowess to this point.
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