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The goal of this article is to show how you can easily stream the sound captured by a microphone connected to the Raspberry Pi to another distant machine. In order to do this, you will need:

sudo apt-get install vlc

Next, you should plug your USB sound card to the RAspberry Pi and plug the microphone to the USB soundcard. We can then check if the Raspberry Pi sees the USB soundcard using:

pi@raspberrypi:~ $cat /proc/asound/modules  This command should show that the Raspberry pi detected two soundcards: 0 snd_bcm2835 1 snd_usb_audio  Now let’s check that the microphone part of the USB soundcard is properly detected: pi@raspberrypi:~$ arecord –l

**** List of CAPTURE Hardware Devices ****
card 1: Device [USB PnP Sound Device], device 0: USB Audio [USB Audio]
Subdevices: 1/1
Subdevice #0: subdevice #0


The Raspberry Pi is here showing that the microphone plugged to the soundcard is detected as device 0, plugged to soundcard 1.

We can then test this microphone, first by simply recording a few seconds and checking that it works:

arecord -D hw:1,0 -d 10 -f cd test.wav -c 1


Ẁhere:

• -D: We want to use a recording device
• Hw:1,0: We’ll use device 0 plugged to soundcard 1
• -d 10: We’ll record 10 seconds of sound
• -f cd test.wav: The file will be saved in the current folder, and will be names test.wav
• -c 1: Use 1 if you are using a mono microphone, 2 for stereo

After 10 seconds, you should have control over the prompt again, and you can listen to the recodring using:

aplay test.wav


(If your Raspberry Pi is plugged to a TV using HDMI the defaul sound output will be the HDMI) If you are able to listen to the sound recorded by the mic and it seems fine, we can now try to send it over the network.

The first method we can try is to simply send the uncompressed audio feed from the microphone using SSH tunneling:

arecord -D plughw:1,0 -f dat | ssh -C user@remoteip aplay -f dat


Where user@remoteip are the SSH credentials of the distant machine on the network that you’d like to stream the feed to. You will not need to do anything on the distant machine (except turning ON the audio), the feed will automatically start. The distant machine needs to have SSH activated. This solution induces a latency, on my Raspberry Pi, of about 1-5 seconds and appears to consume quite a lot of CPU reesources.

Another solution, which appears to be more efficient, consists in compressing the feed in MP3 before sending it over the network. This is possible using VLS and the RPT protocole, you can simply input:

cvlc -vvv alsa://hw:1,0 --sout \
'#transcode{acodec=mp3,ab=128}:rtp{mux=ts,dst=239.255.1.1,sdp=sap}'


In this case, the audio feed will be sent as an 128kbps MP3 feed to the 239.255.1.1 destination. To access it, input rpt://239.255.1.1 in the network feeds of VLC on any machine connected to the same network. The audio feed should then start on VLC.

I have sources for this and will add it later._

This is a cross-post from Colper Science The original post is at http://blog.colperscience.com/2018/02/16/lariviere-talk/.

McGill will celebrated the Open Access Week International (October 23-29 2-17) with events designed to bring awareness to newer aspects of the scholarly communication lifecycle. Vincent Larivière, Canada Research Chair in the Transformations of Scholarly Communication and associate professor of information science at the École de bibliothéconomie et des sciences de l’information (l’Université de Montréal) gave a talk entitled “Scholarly communication and open access: what researchers should know”.

The complete presentation is available here and we recommend that you take a look at the slides while listening to the first half of this episode, which is the first section of Vincent Larivière’s presentation. We will discover how publishing in researcher became what it is today and an explanation of how having five big companies dominate this field affects researchers.

In the second part of this episode, we will present a short interview we had with Vincent Lariviere about an interesting event which happened here, at Université de Montreal, during the summer of 2017: the library’s university refused to renew one of the big deals it had with Taylor and Francis Group and had to go through tough negotiations with the publisher. Vinvent Lariviere was part of these negotiation and will tell us a little bit more about the role he played there.

A quick post to share an experiment, again, I did a few months again. This is a very “basic” test in which pull on a PMMA “dogbone” until it breaks. The specimen is being pulled at a constant loading speed of 2000N every minute. The stress strain plot is also presented here. An interesting fact to notice here is that the DIC method was able to capture the different in elastic and plastic deformation at the very end of the test (the very last point of the plot).

This test’s were of interest to some fellow researchers but I had no plan publishing them or anything, I was still interested in sharing these results and getting some “credit” for it (“credit”, in research, is usually understood as citations). This is, I believe, a pretty big issue for experimental researchers as only publications seem to matter in research, the Open Data for Experimental Mechanics project is actually focused on this issue. A solution for experimental researchers is to upload their dataset on the Zenodo platform. A DOI is then attributed to the dataset and the experimental results can be cited by other researchers, even if there is no paper attached to the experimental results.

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A quick post to share an experiment I did back in 2016 in cooperation with Qinghua Wu. Qinghua’s research is mainly about 3D-printing chitosan, a natural polysacharride which is the structural element in the exoskeleton of shrimps and other crustaceans. Chitosan has several very nice properties, it is completely natural, it is biocompatible and is an antibacterial agent. However, it has the big disadvantage of only being able to sustain low loads especially when it is hydrated. Qinghua is also able to 3D print films of this polymer using the solvent cast 3D-printing method so we decided to investigate how a crack grows in this material.

We took a rectangular shaped film of chitosan, and covered it with a mist of black paint dots using and air gun. We then precracked it using a razor blade. The material is then inserted in a tensile testing machine and a stereocamera rig was setup in front of the tensile testing machine.

The black paint dots were used as a speckle pattern for the DIC algorithm after the test. It was thus possible to obtain the displacement and strain fields while the crack is growing.

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This is a cross-post from opendataexpmechanics.github.io. The original post is at opendataexpmechanics.github.io. The purpose of this post is to introduce a new open source project I will be working on during the next year with Patrick Diehl.

### Context and background

Patrick and I, Ilyass, met in March 2015 through Twitter. We started exchanging about Peridynamics, a novel theory for modelling of materials in mechanics. I was, and still am, extremely interested in that theory as it appeared to be a theory upon which a model could be built to perform simulation of some complex experiments I was working on. We started working around this theory, I went to Patrick’s lab in Germany as an invited researcher, and Patrick is now a fellow in the laboratory I am part of at Polytechnique Montreal.

In our every day work, I mostly do experimental work, I set up experiments involving several materials being pulled and broken apart while measuring displacements and loads; Patrick, on the other hand, mostly focuses on programming and implementing models to perform the best possible simulations of the experiments I setup in the laboratory. It is through this workflow that we started realizing that other publications about similar experiments did not contain enough information to completely model the experiment or reproduce it. The complete raw experimental data is usually not available, and, when it is possible to get the raw data, it is quite hard to work with since there is no standardized format to present that data. The experiments we do in the laboratory also started to appear less and less valuable, the only thing that appeared to be really valuable are the publications which could be written out of the experimental data.

A few weeks ago, we heard of the Mozilla Science Mini-Grants and decided to try to use this opportunity to setup a project addressing these issues. We worked hard to be able to send a grant demand to the Mozilla foundation and decided to share some of the answers we sent to the foundation in this blog, which will also be used to track the project’s progress.

### The issues

The availability of experimental results is limited, because they are scattered in publications. The access to experimental data could be beneficial for mechanical engineers and computational engineers to improve their research. In publications details necessary to reproduce the experiment or design the simulation for a benchmark are often missing. A platform is therefore needed to share experimental data sets in mechanics, rating it with respect to reproducibility and quality of the experimental setup for benchmarks with simulation results. Thus, both communities could enhance the understanding of material behavior and fasten their research.

### First project description

Accessible reliable and fully described experimental data is critically lacking in the materials/mechanics community to validate accurate predictive models. Our project proposes a platform for researchers to present their experimental results as standardized datasets. Experimental researchers can then obtain a DOI for their datasets, making them citable by others.

### Coming up with a solution

We used the Open Canvas designed by the Mozilla Foundation to try to clearly define the project we would work on. The canvas helps linking a product, which solves a problem, to users and contributors. Contributors are critical for any open source project, which is why they are included in this canvas. The canvas summarizes the whole project’s purpose.

### Users

Experimental engineers will benefit from sharing their results by getting citations. It could be a motivation to provide their data on our platform. Computational engineers could use this data as benchmarks for their simulations and rating the data could improve the quality and make it more valuable for the community.

### Description of the platform

The current form we have in mind for the project is a web platform. The platform itself will be a repository for datasets for experimental mechanics and materials. Users will be able to upload a PDF document clearly explaining the experiment and the data format. The experiment’s raw data itself will be either stored on our servers, if the total size is not too large, or stored on a University’s servers and linked to them. Other users will be able to login and research through the datasets available by category, kind of tests, materials and other classifiers to be determined later. The data can directly be downloaded by the user.

### Planning

• Phase 1 - Initial platform development

During the next months, we will firstly be working on developing an initial version of the platform. Once we have a first functional version, we will move to the second phase.

• Phase 2 - Platform/repository launch

The platform’s code will be made public on Github in our repository. The platform will also be officialy launched. At that point, we will start looking for contributors to help us develop the platform and include new features. We will start advertising the platform to try to get more experimental results available for the users.

• Phase 3 - Sustaining the platform and advertising it

During the last phase, we will keep working on the previously mentionned activities and will also start focusing on means to make the platform sustainable. We will also focus on monitoring the platform to measure and quantify the outputs to see if we are reaching the objectives we defined at the beginning of the project.

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Colper Science is a podcasting project Kambiz Chizari and I started during the Mozilla Sprint 2017.

Colper Science a bi-weekly podcast about Open Science and its methods. Each episode is an interview with someone somewhoe related to Open Science. We believe that is today possible for researchers to fully migrate to the world of Open Science using tools and methods already available out there, but most of these tools, methods and possibilities remain unknown by most of the research community. Colper Science’s purpose is to let everybody know about these tools by sharing success stories around Open Science.

Listen to Episode 01:

Bonus:

Subscribe to the podcast’s RSS feed.

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I manufactured a standard dogbone specimen similar to the one shown in the picture below sometime last year. Instead of using a plain monofiber, I decided to embed a Carbon Fiber (CF) bundle in it. I found some CF in our laboratory at Polytechnique and worked on a method to manufacture the specimen I had in mind.

The setup used here is the same as the one presented in the post Optical microscope Digital Image Correlation. In the GIF clip above, the specimen is shown first, and the bundle of carbon fiber going through it are indicated with a metallic ruler I am holding. The next scene shows the microtensile testing rig installed under the Olympus confocal laser microscope, a specimen is shown while being tested. In the final scene, the computer screen plugged to the microscope is shown. It is possible to see a PTFE fiber in an epoxy matrice while interfacial debonding it starting to happen. That was the specimen I was testing at the moment I shot this clip.

The specimen was loaded in the microtensile testing machine, the whole rig is put under the confocal laser microscope after what the test started. These kind of tests take about 8 hours long: the specimen is loaded displacement by pulling on the microtensile testing machine by a step inferior to ($$100 \mu m$$, the microtensile testing machine is then stopped and a picture is snapped with the confocal laser (a single picture takes about 3 minutes because of the confocal scanning process). The specimen is then pulled again and these steps are repeated until a crack is observed. The purpose of this test is to observe crack initiation and propagation inside a bundle of CF. For this specimen, I stopped the test when the crack was large enough to cover the whole field of view, but before it broke the specimen in two separate parts. I then used some photoelastic film again (similar to the one presented in this post) and glued it on both sides of the specimen. The photoelastic film reveals the strain field within a polymer, the more fringes are visible in an area the higher the strian field is (more explanation were provided in this post).

The result reveals the residual stresses remaining in the specimen after this test. It is possible to see how the CF bundle affected the strain field in its vicinity. The final purpose of this experiment is to somehow come up with a method to perform DIC on the images obtained using the confocal laser microscope.

These experiments were done with the help of Damien Texier and were done at École de Technologie Supérieur, Montréal.

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