Computers Math

Given the growing importance of graphite in energy storage technologies, a team of Northwestern researchers has conducted a study exploring ways to reduce reliance on imports of the in high-demand mineral, which powers everything from electric vehicles (EVs) to cell phones.
The paper, which published this week in the journal Environmental Science and Technology, is the first natural and synthetic graphite material flow analysis for the U.S., and considers 11 end-use applications for graphite, two waste management stages and three recycling pathways.
“If we want to produce more batteries domestically, we’re going to need to increase our production of graphite,” said Northwestern University chemical engineer Jennifer Dunn. “But the question is, how can we do so in a way that contributes to decarbonization goals?”
Dunn is an associate professor of chemical and biological engineering at Northwestern’s McCormick School of Engineering and director of the Center for Engineering Sustainability and Resilience. The paper was co-authored by Jinrui Zhang, who at the time of the study initiation was a post-doctoral scholar in chemical and biological engineering, and Chao Liang, previously a member of Northwestern’s Institute for Sustainability and Energy (ISEN). Both co-authors are alumni of Dunn’s research group.
The U.S. uses mostly synthetic graphite, which is produced from by-products of the fossil fuel industry and creates a paradoxical relationship between graphite and technologies like electric vehicles (EVs) that aim to remove fossil fuel supply chains from transportation and cut greenhouse gas emissions.
Natural graphite, alternately, is sourced from mines and imported to the U.S. mostly from China. Nearly all the graphite used in the U.S. goes into electrodes for steel manufacturing. As the battery supply chain in the U.S. ramps up, measures like the Inflation Reduction Act seek to incentivize the use of domestically sourced materials — including graphite — in U.S.-made batteries.

Given the growing importance of graphite in energy storage technologies like lithium-ion batteries, the team carried out this analysis to characterize the major production routes of the mineral, its main uses and opportunities to reduce consumption through recycling. Data from 2018 — the most recent period with sufficient data for this type of analysis — was used for the study.
Most of the graphite consumed in the U.S. in 2018 was synthetic graphite, with 63% of this graphite produced domestically. Production of synthetic graphite emits more greenhouse gases than mining natural graphite (Natural graphite has between 62% and 89% lower greenhouse gas emissions). Synthetic graphite is also more expensive. However, the U.S. does not mine natural graphite but imports it, predominately from China.
As the only material that conducts electricity besides metal, the main use of graphite is for electrodes in steel making. As demand for low-carbon steel increases, more graphite may be consumed in electrode production. During steel making, graphite burns and dissipates — much like how graphite pencils start to disappear as you write with them. Though it is not impossible to recover dissipated graphite, it rarely is, diminishing opportunities to recover the mineral through recycling. Technologies to recover graphite from lithium-ion batteries are increasing in maturity but not yet common.
Dunn said that part of the focus on domestic sources and recycling of graphite-containing products like lithium-ion batteries is based on the current supply chain’s potential instability and projected increasing demand.
“You can recover some graphite from recycling lithium-ion batteries, but batteries last a while, so it may be a decade before you can get graphite back from EVs that reach the end of their life,” Dunn said. “However, we are also building the bioeconomy in the U.S., and that can include making graphite from biomass. This opens up another supply option beyond making graphite from fossil fuel industry by-products or mining.”
With the passage of the Inflation Reduction Act of 2022, more funding will move toward the use of domestically sourced and recycled graphite, and Dunn said the U.S. needs to be ready to make the shift.
The study, “Graphite flows in the U.S.: Insights into a key ingredient of the energy transition,” was supported by the National Science Foundation’s Future Manufacturing Program (NSF CMMI-2037026). More

Imagine you can open your fridge, open an app on your phone and immediately know which items are expiring within a few days. This is one of the applications that a new technology developed by engineers at the University of California San Diego would enable.
The technology combines a chip integrated into product packaging and a software update on your phone. The phone becomes capable of identifying objects based on signals the chip emits from specific frequencies, in this case Bluetooth or WiFi. In an industrial setting, a smartphone equipped with the software update could be used as an RFID reader.
The work harnesses breakthroughs in backscatter communication, which uses signals already generated by your smartphone and re-directs them back in a format your phone can understand. Effectively, this technique uses 1000 less power than state of the art to generate WiFi signals These advances have enabled very low-power communication between components of the Internet of Things and hardware such as WiFi or Bluetooth transceivers, for applications such as on-body sensors or asset trackers.
The custom chip, which is roughly the size of a grain of sand and costs only a few pennies to manufacture, needs so little power that it can be entirely powered by LTE signals, a technique called RF energy harvesting. The chip turns Bluetooth transmissions into WiFi signals, which can in turn be detected by a smartphone with that specific software update.
The team will present their work at the IEEE International Solid-State Circuits Conference in San Francisco on Feb. 20, 2023.
Currently, state of the art backscatter modulation requires two external devices: one to transmit and one to receive and read the signals. This conference paper presents the first backscatter integrated circuit that can enable wireless communication and battery-less operation coming from a single mobile device.

“This approach enables a robust, low-cost and scalable way to provide power and enable communications in an RFID-like manner, while using smartphones as the devices that both read and power the signals,” said Patrick Mercier, one of the paper’s senior authors and a professor in the Department of Electrical and Computer Engineering at the University of California San Diego.
The technology’s broader promise is the development of devices that do not need batteries because they can harvest power from LTE signals instead. This in turn would lead to devices that are significantly less expensive, last longer, up to several decades, said Dinesh Bharadia, a professor in the UC San Diego Department of Electrical and Computer Engineering and one of the paper’s senior authors.
“E-waste, especially batteries, is one of the biggest problems the planet is facing, after climate change,” Bharadia said.
How it works
The researchers achieved this breakthrough by harvesting power from LTE smartphone signals and buffering this power onto an energy storage capacitor. This in turn activates a receiver that detects Bluetooth signals, which are then modified into reflected WiFi signals.

The software update is simply a bit sequence that turns the Bluetooth signal into something that can be more easily turned into a WiFi signal.
In addition, most lower power wireless communications require custom protocols, but the device the researchers developed relies on common communication protocols: Bluetooth, WiFi and LTE. That’s because smartphones are equipped with both a Bluetooth transmitter and a WiFi receiver.
The device has a range of one meter-about one yard. Adding a battery would boost the tag’s range to tens of meters, but also increase costs. The device, which is half a square inch in size, costs just a few cents to manufacture.
Next steps
Next steps include integrating the technology in other research projects to demonstrate its capabilities.
The team also hopes to commercialize the device, either through a startup or through an industry partner.
The work was supported by the National Science Foundation under Grant 1923902 and the UC San Diego Center for Wearable Sensors.
An LTE-harvesting BLE-to-WiFi Backscattering Chip for Single-Device RFID-like Interrogation
Shih-Jai Kuo*, Manideep Dunna*, Hongyu Lu, Akshit Agarwal, Dinesh Bharadia, Patrick Mercier, Department of Electrical and Computer Engineering, University of California San Diego
*co-primary authors More

In recent years, wearable devices such as smartwatches and rings, as well as smart scales, have become ubiquitous — “must-haves” for the health conscious to self-monitor heart rate, blood pressure, and other vital signs. Despite the obvious benefits, certain fitness and wellness trackers could also pose serious risks for people with cardiac implantable electronic devices (CIEDs) such as pacemakers, implantable cardioverter defibrillators (ICDs), and cardiac resynchronization therapy (CRT) devices, reports a new study published in Heart Rhythm, the official journal of the Heart Rhythm Society, the Cardiac Electrophysiology Society, and the Pediatric & Congenital Electrophysiology Society, published by Elsevier.
Investigators evaluated the functioning of CRT devices from three leading manufacturers while applying electrical current used during bioimpedance sensing. Bioimpedance sensing is a technology that emits a very small, imperceptible current of electricity (measured in microamps) into the body. The electrical current flows through the body, and the response is measured by the sensor to determine the person’s body composition (i.e., skeletal muscle mass or fat mass), level of stress, or vital signs, such as breathing rate.
“Bioimpedance sensing generated an electrical interference that exceeded Food and Drug Administration-accepted guidelines and interfered with proper CIED functioning,” explained lead investigator Benjamin Sanchez Terrones, PhD, Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, UT, USA. He emphasized that the results, determined through careful simulations and benchtop testing, do not convey an immediate or clear risk to patients who wear the trackers, but noted that the different levels emitted could result in pacing interruptions or unnecessary shocks to the heart. Dr. Sanchez added, “our findings call for future clinical studies examining patients with CIEDs and wearables.”
The interaction between general electrical appliances, and more recently smart phones, with CIEDs has been subject to study within the scientific community over the past few years. Nearly all, if not all, implantable cardiac devices already warn patients about the potential for interference with a variety of electronics due to magnetic fields — for example, carrying a mobile phone in your breast pocket near a pacemaker. The rise of wearable health tech has grown rapidly in recent years, blurring the line between medical and consumer devices. Until this study, objective evaluation for ensuring safety has not kept pace with the exciting new gadgets.
“Our research is the first to study devices that employ bioimpedance-sensing technology as well as discover potential interference problems with CIEDs such as CRT devices. We need to test across a broader cohort of devices and in patients with these devices. Collaborative investigation between researchers and industry would be helpful for keeping patients safe,” noted Dr. Sanchez Terrones. More

A database updated in 2022 reported around 4,852 active satellites orbiting the earth. These satellites serve many different purposes in space, from GPS and weather tracking to military reconnaissance and early warning systems. Given the wide array of uses for satellites, especially in low Earth orbit (LEO), researchers are constantly trying to develop better ones. In this regard, small satellites have a lot of potential. They can reduce launch costs and increase the number of satellites in orbit, providing a better network with wider coverage. However, due to their smaller size, these satellites have lesser radiation shield. They also have a deployable membrane attached to the main body for a large phased-array transceiver, which causes non-uniform radiation degradation across the transceiver. This affects the performance of the satellite’s radio due to the variation in the strength of signal they can sense — also known as gain variation. Thus, there is a need to mitigate radiation degradation to make small satellites more viable.

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Engineering researchers at the University of Waterloo are successfully using a robot to help keep children with learning disabilities focused on their work.
This was one of the key results in a new study that also found both the youngsters and their instructors valued the positive classroom contributions made by the robot.
“There is definitely a great potential for using robots in the public education system,” said Dr. Kerstin Dautenhahn, a professor of electrical and computer engineering. “Overall, the findings imply that the robot has a positive effect on students.”
Dautenhahn has been working on robotics in the context of disability for many years and incorporates principles of equity, inclusion and diversity in research projects.
Students with learning disabilities may benefit from additional learning support, such as one-on-one instruction and the use of smartphones and tablets.
Educators have in recent years explored the use of social robots to help students learn, but most often, their research has focused on children with Autism Spectrum Disorder. As a result, little work has been done on the use of socially assistive robots for students with learning disabilities.

Along with two other Waterloo engineering researchers and three experts from the Learning Disabilities Society in Vancouver, Dautenhahn decided to change this, conducting a series of tests with a small humanoid robot called QT.
Dautenhahn, the Canada 150 Research Chair in Intelligent Robotics, said the robot’s ability to perform gestures using its head and hands, accompanied by its speech and facial features, makes it very suitable for use with children with learning disabilities.
Building on promising earlier research, the researchers divided 16 students with learning disabilities into two groups. In one group, students worked one-on-one with an instructor only. In the other group, the students worked one-on-one with an instructor and a QT robot. In the latter group, the instructor used a tablet to direct the robot, which then autonomously performed various activities using its speech and gestures.
While the instructor controlled the sessions, the robot took over at certain times, triggered by the instructor, to lead the student.
Besides introducing the session, the robot set goals and provided self-regulating strategies, if necessary. If the learning process was getting off-track, the robot used strategies such as games, riddles, jokes, breathing exercises and physical movements to redirect the student back to the task.
Students who worked with the robot, Dautenhahn said, “were generally more engaged with their tasks and could complete their tasks at a higher rate compared” to the students who weren’t assisted by a robot. Further studies using the robot are planned.
A paper on the study, User Evaluation of Social Robots as a Tool in One-to-one Instructional Settings for Students with Learning Disabilities, was recently presented at the International Conference on Social Robotics in Florence, Italy. More

For the first time, an international team of researchers, including those from the University of Tokyo’s Institute for Solid State Physics, has demonstrated a switch, analogous to a transistor, made from a single molecule called fullerene. By using a carefully tuned laser pulse, the researchers are able to use fullerene to switch the path of an incoming electron in a predictable way. This switching process can be three to six orders of magnitude faster than switches in microchips, depending on the laser pulses used. Fullerene switches in a network could produce a computer beyond what is possible with electronic transistors, and they could also lead to unprecedented levels of resolution in microscopic imaging devices.
Over 70 years ago, physicists discovered that molecules emit electrons in the presence of electric fields, and later on, certain wavelengths of light. The electron emissions created patterns that enticed curiosity but eluded explanation. But this has changed thanks to a new theoretical analysis, the ramification of which could not only lead to new high-tech applications, but also improve our ability to scrutinize the physical world itself. Project Researcher Hirofumi Yanagisawa and his team theorized how the emission of electrons from excited molecules of fullerene should behave when exposed to specific kinds of laser light, and when testing their predictions, found they were correct.
“What we’ve managed to do here is control the way a molecule directs the path of an incoming electron using a very short pulse of red laser light,” said Yanagisawa. “Depending on the pulse of light, the electron can either remain on its default course or be redirected in a predictable way. So, it’s a little like the switching points on a train track, or an electronic transistor, only much faster. We think we can achieve a switching speed 1 million times faster than a classical transistor. And this could translate to real world performance in computing. But equally important is that if we can tune the laser to coax the fullerene molecule to switch in multiple ways at the same time, it could be like having multiple microscopic transistors in a single molecule. That could increase the complexity of a system without increasing its physical size.”
The fullerene molecule underlying the switch is related to the perhaps slightly more famous carbon nanotube, though instead of a tube, fullerene is a sphere of carbon atoms. When placed on a metal point — essentially the end of a pin — the fullerenes orientate a certain way so they will direct electrons predictably. Fast laser pulses on the scale of femtoseconds, quadrillionths of a second, or even attoseconds, quintillionths of a second, are focused on the fullerene molecules to trigger the emission of electrons. This is the first time laser light has been used to control the emission of electrons from a molecule in this way.
“This technique is similar to the way a photoelectron emission microscope produces images,” said Yanagisawa. “However, those can achieve resolutions at best around 10 nanometers, or ten-billionths of a meter. Our fullerene switch enhances this and allows for resolutions of around 300 picometers, or three-hundred-trillionths of a meter.”
In principle, as multiple ultrafast electron switches can be combined into a single molecule, it would only take a small network of fullerene switches to perform computational tasks potentially much faster than conventional microchips. But there are several hurdles to overcome, such as how to miniaturize the laser component, which would be essential to create this new kind of integrated circuit. So, it may still be many years before we see a fullerene switch-based smartphone. More