INAE Monthly E-News Letter Vol. VIII, Issue 9, September 1, 2017

 (+) Academy Activities

From the Editor’s Desk

There is no better engineered product than life itself

Engineers are using advanced engineering tools and methods, and at the same time are getting familiar with the tools of modern biology. Quantitative and computational approaches are becomi Read more...

Purnendu Ghosh
Chief Editor of Publications

 (+) Editorial Board, INAE

 (+) Articles by INAE Fellows

Dr Purnendu Ghosh
Dr Baldev Raj
Dr K V Raghavan
Dr Sanak Mishra
Prof. Indranil Manna
Prof BS Murty
Prof Sanghamitra Bandyopadhyay
Prof Pradip Dutta
Prof Manoj K Tiwari
Prof Sanjay Mittal
Prof Prasun K Roy
Brig Rajan Minocha

 (+) Engineering and Technology Updates

  Civil Engineering

  Computer Engineering  and Information Technology

  Mechanical Engineering

  Chemical Engineering

  Electrical Engineering

  Electronics and Communication Engineering

  Aerospace Engineering

  Mining, Metallurgical and Materials Engineering

  Energy Engineering

  Interdisciplinary Engineering and Special Fields 

 (+) Engineering Innovation in India
 (+) Previous E-newsletter

 

Civil Engineering

1. Indented Cement Shows Unique Properties

Indented tobermorite, a natural analog to the calcium-silicate-hydrate mix in cement, responds differently than bulk tobermorite, depending on the size of the indentation and the force. Layers that bond through indentation remain that way after the force is removed, according to Rice University engineers.

Rice University scientists have determined that no matter how large or small a piece of tobermorite is, it will respond to loading forces in precisely the same way. But poking it with a sharp point will change its strength.

Tobermorite is a naturally occurring crystalline analog to the calcium-silicate-hydrate (C-S-H) that makes up cement, which in turn binds concrete, the world’s most-used material. A form of tobermorite used by ancient Romans is believed to be a key to the legendary strength of their undersea concrete structures.The finely layered material will deform in different ways depending on how standard forces — shear, compression and tension — are applied, but the deformation will be consistent among sample sizes, according to Rice materials scientist Rouzbeh Shahsavari. For their latest survey, Shahsavari built molecular dynamics models of the material. Their simulations revealed three key molecular mechanisms at work in tobermorite that are also likely responsible for the strength of C-S-H and other layered materials. One is a mechanism of displacement in which atoms under stress move collectively as they try to stay in equilibrium. Another is a diffusive mechanism in which atoms move more chaotically. They found that the material maintains its structural integrity best under shear, and less so under compressive and then tensile loading.More interesting to the researchers was the third mechanism, by which bonds between the layers were formed when pressing a nanoindenter into the material. A nanoindenter is a device used to test the hardness of very small volumes of materials. The high stress at the point of indentation prompted local phase transformations in which the crystalline structure of the material deformed and created strong bonds between the layers, a phenomenon not observed under standard forces. The strength of the bond depended on both the amount of force and, unlike the macroscale stressors, the size of the tip.”There is significant stress right below the small tip of the nanoindenter,” Shahsavari said. “That connects the neighbouring layers. Once you remove the tip, the structure does not go back to the original configuration. That’s important: These transformations are irreversible.”Besides providing fundamental understanding on key deformation mechanisms, this work uncovers the true mechanical response of the system under small localized (versus conventional) loads, such as nanoindentation,” he said. “If changing the tip size (and thus the internal topology) is going to alter the mechanics — for example, make the material stronger — then one might use this feature to better design the system for particular localized loads.”Shahsavari is an assistant professor of civil and environmental engineering and of materials science and nanoengineering.

 

Source : https://www.sciencedaily.com/releases/2017/07/170719173712.htm

 

Computer Engineering and Information Technology

2.  Reshaping Computer-Aided Design

Adriana Schulz, an MIT PhD student in the Computer Science and Artificial Intelligence Laboratory, demonstrates the InstantCAD computer-aided-design-optimizing interface.

Almost every object we use is developed with computer-aided design (CAD). Ironically, while CAD programs are good for creating designs, using them is actually very difficult and time-consuming if you’re trying to improve an existing design to make the most optimal product.Researchers from MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) and Columbia University are trying to make the process faster and easier: In a new paper, they’ve developed InstantCAD, a tool that lets designers interactively edit, improve, and optimize CAD models using a more streamlined and intuitive workflow. InstantCAD integrates seamlessly with existing CAD programs as a plug-in, meaning that designers don’t have to learn new tools to use it.”From more ergonomic desks to higher-performance cars, this is really about creating better products in less time,” says Department of Electrical Engineering and Computer Science PhD student and lead author Adriana Schulz. “We think this could be a real game changer for automakers and other companies that want to be able to test and improve complex designs in a matter of seconds to minutes, instead of hours to days.”Traditional CAD systems are “parametric,” which means that when engineers design models, they can change properties like shape and size (“parameters”) based on different priorities. For example, when designing a wind turbine you might have to make trade-offs between how much airflow you can get versus how much energy it will generate.

However, it can be difficult to determine the absolute best design for what you want your object to do, because there are many different options for modifying the design. On top of that, the process is time-consuming because changing a single property means having to wait to regenerate the new design, run a simulation, see the result, and then figure out what to do next.With InstantCAD, the process of improving and optimizing the design can be done in real-time, saving engineers days or weeks. After an object is designed in a commercial CAD program, it is sent to a cloud platform where multiple geometric evaluations and simulations are run at the same time.With this precomputed data, you can instantly improve and optimize the design in two ways. With “interactive exploration,” a user interface provides real-time feedback on how design changes will affect performance, like how the shape of a plane wing impacts air pressure distribution. With “automatic optimization,” you simply tell the system to give you a design with specific characteristics, like a drone that’s as lightweight as possible while still being able to carry the maximum amount of weight.The reason it’s hard to optimize an object’s design is because of the massive size of the design space (the number of possible design options).”It’s too data-intensive to compute every single point, so we have to come up with a way to predict any point in this space from just a small number of sampled data points,” says Schulz. “This is called ‘interpolation,’ and our key technical contribution is a new algorithm we developed to take these samples and estimate points in the space.” A researcher says InstantCAD could be particularly helpful for more intricate designs for objects like cars, planes, and robots, particularly for industries like car manufacturing that care a lot about squeezing every little bit of performance out of a product.”Our system doesn’t just save you time for changing designs, but has the potential to dramatically improve the quality of the products themselves,” says a researcher. “The more complex your design gets, the more important this kind of a tool can be.”Because of the system’s productivity boosts and CAD integration, Schulz is confident that it will have immediate applications for industry. Down the line, she hopes that InstantCAD can also help lower the barrier for entry for casual users.”In a world where 3-D printing and industrial robotics are making manufacturing more accessible, we need systems that make the actual design process more accessible, too,” Schulz says. “With systems like this that make it easier to customize objects to meet your specific needs, we hope to be paving the way to a new age of personal manufacturing and DIY design.”



Source : https://www.sciencedaily.com/releases/2017/07/170724172557.htm
 

 

Mechanical Engineering

3.  Graphene-Like Materials Printed with Inkjet Printer

Researchers team has developed inks made of graphene-like materials for inkjet printing. New black phosphorous inks are compatible with conventional inkjet printing techniques for optoelectronics and photonics.

An international research team has developed inks made of graphene-like materials for inkjet printing. New black phosphorus inks are compatible with conventional inkjet printing techniques for optoelectronics and photonics.Since the discovery of the Nobel Prize winning material graphene, many new nanomaterials promise to deliver exciting new photonic and optoelectronic technologies. Black phosphorus is a particularly interesting post-graphene nanomaterial for next generation photonic and optoelectronic devices. Yet despite remarkable performance in the lab, practical real-world exploitation of this material has been hindered by complex material fabrication and its poor environmental stability. “Our inkjet printing demonstration makes possible for the first time the scalable mass fabrication of black phosphorus based photonic and optoelectronic devices with long-term stability necessary for a wide range of industrial applications,” tells Professor Zhipei Sun at Aalto University in Finland.Scientists optimized the chemical composition to achieve a stable ink through the balance of complex and competing fluidic effects. This enabled the production of new functional photonic and optoelectronic devices by inkjet printing with excellent print quality and uniformity — just like the printing of intricate graphics or photographs on paper. The researchers’ work demonstrated the benefits of their novel technique by inkjet printing devices that take advantage of the properties of black phosphorus, not least its semiconducting bandgap that can be readily varied by engineering the number of atomic layers and can cover the visible and near-infrared region of the electromagnetic spectrum.The researchers also demonstrated printed black phosphorus based nonlinear optical devices that can be easily inserted into lasers to act as ultra-quick optical shutters, converting a continuous beam of laser radiation into a repetitive series of very short bursts of light suited for industrial and medical applications, such as machining, imaging and sensing. In the study, black phosphorus was also able to act as an efficient and highly-responsive detector of light, extending the wavelength range over which conventional silicon-based photodetectors can operate.Importantly, the researchers showed that the black phosphorus ink can be seamlessly integrated with existing complementary metal-oxide-semiconductor (CMOS) technologies, while the inkjet printing technique developed offering the prospect of supporting the fabrication of so-called heterostructured materials that aim to capitalize on the benefits of distinct, yet complementary properties of multiple nanomaterial layers through controlled fabrication.



Source: https://www.sciencedaily.com/releases/2017/08/170817110907.htm
 

 

Chemical Engineering

4.  Tough, Self-Healing Rubber Developed

Self-healing rubber links permanent covalent bonds (red) with reversible hydrogen bonds (green).

Imagine a tyre that could heal after being punctured or a rubber band that never snapped. Researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have developed a new type of rubber that is as tough as natural rubber but can also self-heal. Self-healing materials aren’t new — researchers at SEAS have developed self-healing hydrogels, which rely on water to incorporate reversible bonds that can promote healing. However, engineering self-healing properties in dry materials — such as rubber — has proven more challenging. That is because rubber is made of polymers often connected by permanent, covalent bonds. While these bonds are incredibly strong, they will never reconnect once broken. In order to make a rubber self-healable, the team needed to make the bonds connecting the polymers reversible, so that the bonds could break and reform. “Previous research used reversible hydrogen bonds to connect polymers to form a rubber but reversible bonds are intrinsically weaker than covalent bonds,” said Li-Heng Cai, a postdoctoral fellow at SEAS and corresponding author of the paper. “This raised the question, can we make something tough but can still self-heal?” Cai, along with co- workers developed a hybrid rubber with both covalent and reversible bonds. The concept of mixing both covalent and reversible bonds to make a tough, self-healing rubber was proposed in theory by Cai but never shown experimentally because covalent and reversible bonds don’t like to mix. “These two types of bonds are intrinsically immiscible, like oil and water,” said Cai. So, the researchers developed a molecular rope to tie these two types of bonds together. This rope, called randomly branched polymers, allows two previously unmixable bonds to be mixed homogeneously on a molecular scale. In doing so, they were able to create a transparent, tough, self-healing rubber. Typical rubber tends to crack at certain stress point when force is applied. When stretched, hybrid rubber develops so-called crazes throughout the material, a feature similar to cracks but connected by fibrous strands. These crazes redistribute the stress, so there is no localized point of stress that can cause catastrophic failure. When the stress is released, the material snaps back to its original form and the crazes heal. Harvard’s Office of Technology Development has filed a patent application for the technology and is actively seeking commercialization opportunities. The self-healing ability is appealing for a wide variety of rubber products. “Imagine that we could use this material as one of the components to make a rubber tyre,” said a researcher. “If you have a cut through the tyre, this tire wouldn’t have to be replaced right away. Instead, it would self-heal while driving enough to give you leeway to avoid dramatic damage.” “There is still a lot more to do,” said researchers. “For materials science, it is not fully understood why this hybrid rubber exhibits crazes when stretched. For engineering, the applications of the hybrid rubber that take advantage of its exceptional combination of optical transparency, toughness, and self-healing ability remain to be explored. Moreover, the concept of using molecular design to mix covalent and reversible bonds to create a homogenous hybrid elastomer is quite general and should enable development of tough, self-healing polymers of practical usage.”



Source: https://www.sciencedaily.com/releases/2017/08/170816122342.htm
 

 

Electrical Engineering

5. New Ultrathin Semiconductor Materials Exceed Some of Silicon’s ‘Secret’ Powers

In this greatly enlarged cross-section of an experimental chip, the bands of black and white reveal alternating layers of hafnium diselenide – an ultrathin semiconductor material – and the hafnium dioxide insulator. The cross-section matches an overlaid color schematic on the right.

The next generation of feature-filled and energy-efficient electronics will require computer chips just a few atoms thick. For all its positive attributes, trusty silicon can’t take us to these ultrathin extremes. Now, electrical engineers at Stanford have identified two semiconductors — hafnium diselenide and zirconium diselenide — that share or even exceed some of silicon’s desirable traits, starting with the fact that all three materials can “rust.” “It’s a bit like rust, but a very desirable rust,” said Eric Pop, an associate professor of electrical engineering.The new materials can also be shrunk to functional circuits just three atoms thick and they require less energy than silicon circuits. Although still experimental, the researchers said the materials could be a step toward the kinds of thinner, more energy-efficient chips demanded by devices of the future.Silicon has several qualities that have led it to become the bedrock of electronics, Pop explained. One is that it is blessed with a very good “native” insulator, silicon dioxide or, in plain English, silicon rust. Exposing silicon to oxygen during manufacturing gives chip-makers an easy way to isolate their circuitry. Other semiconductors do not “rust” into good insulators when exposed to oxygen, so they must be layered with additional insulators, a step that introduces engineering challenges. Both of the diselenides the Stanford group tested formed this elusive, yet high-quality insulating rust layer when exposed to oxygen.Not only do both ultrathin semiconductors rust, they do so in a way that is even more desirable than silicon. They form what are called “high-K” insulators, which enable lower power operation than is possible with silicon and its silicon oxide insulator.As the Stanford researchers started shrinking the diselenides to atomic thinness, they realized that these ultrathin semiconductors share another of silicon’s secret advantages: the energy needed to switch transistors on — a critical step in computing, called the band gap — is in a just-right range. Too low and the circuits leak and become unreliable. Too high and the chip takes too much energy to operate and becomes inefficient. Both materials were in the same optimal range as silicon.All this and the diselenides can also be fashioned into circuits just three atoms thick, or about two-thirds of a nanometer, something silicon cannot do.”Engineers have been unable to make silicon transistors thinner than about five nanometers, before the material properties begin to change in undesirable ways,” Pop said.The combination of thinner circuits and desirable high-K insulation means that these ultrathin semiconductors could be made into transistors 10 times smaller than anything possible with silicon today. “Silicon won’t go away. But for consumers this could mean much longer battery life and much more complex functionality if these semiconductors can be integrated with silicon,” Pop said.There is much work ahead. First, reseaechers must refine the electrical contacts between transistors on their ultrathin diselenide circuits. “These connections have always proved a challenge for any new semiconductor, and the difficulty becomes greater as we shrink circuits to the atomic scale,” a researcher said.

They are also working to better control the oxidized insulators to ensure they remain as thin and stable as possible. Last, but not least, only when these things are in order will they begin to integrate with other materials and then to scale up to working wafers, complex circuits and, eventually, complete systems.”There’s more research to do, but a new path to thinner, smaller circuits — and more energy-efficient electronics — is within reach,” Pop said.



Source : https://www.sciencedaily.com/releases/2017/08/170811141107.htm
 

 

Electronics and Communication Engineering

6. Logic Circuits with Diamond-Based Transistors

Micrograph of a fabricated logic circuit equipped with diamond-based transistors.

A NIMS research group led by Jiangwei Liu (independent scientist, Research Center for Functional Materials) and Yasuo Koide (coordinating director in the Research Network and Facility Services Division) has succeeded for the first time in the world in developing logic circuits equipped with diamond-based MOSFETs (metal-oxide-semiconductor field-effect-transistors) at two different operation modes. This achievement is a first step toward the development of diamond integrated circuits operational under extreme environments.Diamond has high carrier mobility, a high breakdown electric field and high thermal conductivity. Therefore, it is a promising material to be used in the development of current switches and integrated circuits that are required to operate stably at high-temperature, high-frequency, and high-power. However, it had been difficult to enable diamond-based MOSFETs to control the polarity of the threshold voltage, and to fabricate MOSFETs of two different modes―a depletion mode (D mode) and an enhancement mode (E mode)―on the same substrate. The research group has successfully developed a logic circuit equipped with both D- and E-mode diamond MOSFETs after making a breakthrough by fabricating them on the same substrate using a threshold control technique developed by the group.The research group identified the electronic structure in the interface between various oxides and hydrogenated diamond using photoelectron spectroscopy in 2012. The research group then succeeded in developing a diamond MOS (metal-oxide-semiconductor) capacitor with very low leakage current density and an E-mode hydrogenated diamond-based MOSFET in 2013 after going through many difficulties. The group then prototyped logic circuits by combining diamond-based MOSFETs with load resistors in 2014. Finally, the group developed techniques to control D- and E-mode characteristics of diamond-based MOSFETs and identified the control mechanism in 2015. These previous efforts led to the success made in this research project.The logic circuits with diamond-based transistors are promising devices to be used in the development of digital integrated circuits that are required to stably operate under extreme environments such as high-temperature as well as exposure to radiation and cosmic rays.This research was conducted in conjunction with the following projects: Leading Initiative for Excellent Young Researchers, under the sponsorship of the MEXT Human Resource Development Program for Science and Technology; “Development of new functional diamond electronic devices using a large amount of polarized charges”, under the category of Grant-in-Aid for Scientific Research (A) sponsored by the MEXT Grants-in-Aid for Scientific Research; and “Fabrication of high-current output fin-type diamond field-effect transistors”, under the category of Grant-in-Aid for Young Scientists (B) sponsored by the MEXT Grants-in-Aid for Scientific Research. Device fabrication was supported by the NIMS Nanofabrication Platform, established under the MEXT Nanotechnology Platform Japan program.



Source: https://www.sciencedaily.com/releases/2017/08/170802083148.htm
 

 

Aerospace Engineering

7. ISRO Develops Indigenous CCD for Hyperspectral Imaging in Earth Observation Satellites

The testbench.

ISRO has developed an optical imaging detector array for hyperspectal imaging capabilities from Earth orbit. Hyperspectral imaging captures pixel level information across the electromagnetic spectrum, beyond the wavelengths that the human eye can recognise. The development came about during the search for a suitable imaging payload for the Hyperspectral Imaging Satellite (HySIS).The Vir-NIS payload is meant to capture hyperspectral images in the visible and near infrared regions of the electromagnetic spectrum. There are two related methods for obtaining hyperspectral images, push broom scanners and its variant, the whisk broom scanner. ISRO will be using the push broom scanning approach for this particular imaging instrument. The sensor is required to work from an orbit with an altitude of 630 km.Initially ISRO wanted to use an off the shelf detector array from an international commercial supplier, but the shortlisted detectors did not meet the various requirements of ISRO.So, the Space Applications Centre (SAC) and Semi Conductor Limited (SCL), an independent body under the Department of Space worked together for the indigenous development of a Frame Transfer Charge Coupled Device.The SAC came up with the device design, chip layout, chip architecture and the package design. A testbench was also developed to check if the software, hardware and firmware were working as required. The resulting optical imaging detector array was successfully tested to meet the requirements of ISRO.



Source : http://www.firstpost.com/tech/news-analysis/isro-develops-indigenous-ccd-for-hyperspectral-imaging-in-earth-observation-satellites-3909775.html
 

 

Mining, Metallurgical and Materials Engineering

 

8.  Materials Governed by Light

Channelled aluminophosphate with various encapsulated dyes emitting in the blue (acridine), green (pyronin Y) and red (LDS 722) regions of the spectrum, occluded separately (left) or simultaneously in the correct proportions to produce white light (right), under ultraviolet excitation light.

Hybrid materials are those that combine components of differing origins (organic and inorganic) in order to obtain materials different from conventional ones and which display new or improved properties owing to the synergistic effect between their components. Rebeca Sola, a researcher in the Department of Physical Chemistry in the UPV/EHU’s Faculty of Science and Technology, has developed and exhaustively characterised hybrid, photoactive materials — which respond differently when exposed to excitation light — which could have applications in highly different fields, such as optics and biomedicine. In the research conducted in this department, hybrid materials were obtained, among other things, by incorporating fluorescent dyes, which are routinely used in solution, into channelled inorganic structures. These materials firstly give the dye protection, thus rendering it more stable against degradation and increasing the useful service life of the devices that incorporate them, and secondly, they provide the system with rigidity, which is interesting as this has the potential to increase the photophysical properties of the organic hosts (the dyes).As the researcher explained, “highly fluorescent materials in which the dyes are found to be ordered were obtained, thus providing a highly anisotropic response to the linearly polarized light.” In other words, materials that respond differently depending on the direction of the polarization of the incident light. Furthermore, it “is fairly straightforward,” to synthesise these materials said Sola. “Crystalline structures in which the dye has already been occluded inside are obtained without any need to apply a diffusion process to insert the dye into the crystal.” The researcher has thus obtained materials with a very wide range of optical properties. “Of great interest are those in which there is an artificial antenna effect with the ordering of the different kinds of dye and a unidirectional energy transfer,” she said. This is translated into particles with multi-coloured fluorescence, which are capable of picking up the energy from light at one end and transferring it to the opposite end, which could be of interest with respect to integrating them into solar cells.Another of the materials obtained is a solid material that emits delayed fluorescence: instead of the fluorescence of the system turning off as soon as the excitation source is removed, as is usually the case, it persists for tenths of a second and is perfectly visible to the naked eye. “This kind of technology could be of interest in LED technologies,” she explained. And materials capable of transforming incident laser light into light with double the amount of energy were also obtained. These materials not only allow the incorporation of a single dye into the inorganic structure, various dyes can also be simultaneously encapsulated. “With two dyes whose response is complementary, we have obtained fluorescent particles that change colour depending on the light polarization, and change from a blue fluorescent emission to a green one,” added Sola. What is more, it is a reversible, reproducible process.” By incorporating a third, red-emission dye in the correct proportion, a white-light emitting system was also obtained, “once again of interest for illumination systems,” she concluded. White-light emitters were also obtained by adding small organic molecules to certain frameworks of metal ions and organic compounds known as MOFs (Metal Organic Frameworks); ambient-temperature phosphorescence was also obtained with them. “Phosphorescence is an emission process that routinely calls for very low temperatures to prevent the phosphorescent light from deactivating,” explained Sola. The researchers have shown that hybrid materials may have applications in other fields, such as biomedicine. To do this, they used photosensitising substances suitable for photodynamic therapy. These are materials that combine organic and inorganic fragments to produce a kind of oxygen capable of causing the death of certain cells following excitation by light. Photodynamic therapy is a procedure used in dermatology, for example, to treat a range of skin diseases and even for different types of cancer. Materials that not only generate this type of cytotoxic oxygen but which are also fluorescent have been obtained. And “that makes them very useful for bioimaging as well,” added the researcher. “



Source : https://www.sciencedaily.com/releases/2017/08/170804092032.htm
 

 

Energy Engineering 

9. Solar Glasses Generate Solar Power

These Solar Glasses with lens-fitted semitransparent organic solar cells supply two sensors and electronics in the temples with electric power.

Organic solar cells are flexible, transparent, and light-weight — and can be manufactured in arbitrary shapes or colours. Thus, they are suitable for a variety of applications that cannot be realized with conventional silicon solar cells. Researchers from KIT now present sunglasses with coloured, semitransparent solar cells applied onto lenses that supply a microprocessor and two displays with electric power. This paves the way for other future applications such as the integration of organic solar cells into windows or overhead glazing.”We bring solar power to places where other solar technologies fail,” says Dr. Alexander Colsmann, Head of Organic Photovoltaics Group at KIT’s Light Technology Institute (LTI). The “smart” Solar Glasses designed as a case study by the scientist and his team at KIT, is self-powered to measure and display the solar illumination intensity and ambient temperature. The solar cell lenses, perfectly fitted to a commercial frame, have a thickness of approx. 1.6 millimeters and weigh about six grams — just like the lenses of traditional sunglasses. The microprocessor and the two small displays are integrated into the temples of the Solar Glasses. They show the illumination intensity and the ambient temperature as bar graphs. The Solar Glasses also work in indoor environments under illumination down to 500 Lux, which is the usual illumination of an office or a living area. Under these conditions, each of the “smart” lenses still generates 200 milliwatt of electric power — enough to operate devices such as a hearing aid or a step counter.”The Solar Glasses we developed are an example of how organic solar cells may be employed in applications that would not be feasible with conventional photovoltaics,” stresses a researcher who largely contributed to the development of the solar glasses at the Material Research Center for Energy Systems of KIT. In the eyes of the engineer, these solar cells, which are based on hydrocarbons, are very exciting devices due to their mechanical flexibility and the opportunity to adapt their colour, transparency, shape, and size to the desired application.According to the researcher, another field of application is the integration of solar cells into buildings: Since the glass facades of high-rise buildings must often be shaded, it is an obvious option to use organic solar modules for transforming the absorbed light into electric power. A future vision for the engineer, who works on the basic understanding of organic solar cell and semiconductor components at the Material Research Center for Energy Systems, is to coat large surfaces with organic solar cells using reel-to-reel technology. Their research was funded by the BMBF (Federal Ministry of Education and Research) within the scope of the POPUP project which is aimed at developing novel materials and device structures suitable for competitive mass production processes and applications in the field of organic photovoltaics.

 



Source : https://www.sciencedaily.com/releases/2017/08/170802102800.htm
 

 

Interdisciplinary Engineering and Special Fields

10. Cognitive Hearing Aid Filters Out the Noise

A cognitively controlled assistive hearing device can automatically amplify one speaker among many. To do so, a deep neural network automatically separates each of the speakers from the mixture, and compares each speaker with the neural data from the user’s brain. The speaker that best matches the neural data is then amplified to assist the user.

People who are hearing impaired have a difficult time following a conversation in a multi-speaker environment such as a noisy restaurant or a party. While current hearing aids can suppress background noise, they cannot help a user listen to a single conversation among many without knowing which speaker the user is attending to. A cognitive hearing aid that constantly monitors the brain activity of the subject to determine whether the subject is conversing with a specific speaker in the environment would be a dream come true.Using deep neural network models, researchers at Columbia Engineering have made a breakthrough in auditory attention decoding (AAD) methods and are coming closer to making cognitively controlled hearing aids a reality. The study, led by Nima Mesgarani, associate professor of electrical engineering was done in collaboration with Columbia University Medical Center’s Department of Neurosurgery and Hofstra-Northwell School of Medicine, and Feinstein Institute for Medical Research. Mesgarani’s team developed an end-to-end system that receives a single audio channel containing a mixture of speakers by a listener along with the listener’s neural signals, automatically separates the individual speakers in the mixture, determines which speaker is being listened to, and then amplifies the attended speaker’s voice to assist the listener — all in under 10 seconds. “This work combines the state-of-the-art from two disciplines: speech engineering and auditory attention decoding,” says Mesgarani, who is also a member of the Data Science Institute and the Mortimer B. Zuckerman Mind Brain Behaviour Institute. “We were able to develop this system once we made the breakthrough in using deep neural network models to separate speech.” His team came up with the idea of a cognitively controlled hearing aid after they demonstrated it was possible to decode the attended target of a listener using neural responses in the listener’s brain using invasive neural recordings in humans. Two years later, they showed they could decode attention with non-invasive methods as well. “Translating these findings to real-world applications poses many challenges,” notes a research scientist working with Mesgarani and lead author of the study. In a typical implementation of auditory attention decoding, researchers compare the neural responses recorded from a subject’s brain with the clean speech uttered by different speakers; the speaker who produces the maximum similarity with the neural data is determined to be the target and is subsequently amplified. However, in the real world, researchers have access only to the mixture, not the individual speakers. “Our study takes a significant step towards automatically separating an attended speaker from the mixture,” a researcher continues. “To do so, we built deep neural network models that can automatically separate specific speakers from a mixture. We then compare each of these separated speakers with the neural signals to determine which voice the subject is listening to, and then amplify that specific voice for the listener.”The team tested the efficacy of their system using invasive electrocorticography recordings from neurological subjects undergoing epilepsy surgery. They identified the regions of the auditory cortex that contribute to AAD and found that the system decoded the attention of the listener and amplified the voice he or she wanted to listen to, using only the mixed audio. “Our system demonstrates a significant improvement in both subjective and objective speech quality measures — almost all of our subjects said they wanted to continue to use it,” Mesgarani says. “Our novel framework for AAD bridges the gap between the most recent advancements in speech processing technologies and speech prosthesis research and moves us closer to the development of realistic hearing aid devices that can automatically and dynamically track a user’s direction of attention and amplify an attended speaker.”



Source : https://www.sciencedaily.com/releases/2017/08/170803204942.htm

 
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