Physicist Anders Carlsson, at Washington University in St. Louis, and Sid Redner of the Santa Fe Institute have created a new mathematical model to describe the most reliable, efficient and cost-effective way to harness solar power.

Their calculations, recently published in the journal Frontiers in Energy Research, show that small improvements in energy generation and storage could have huge impacts on the overall reliability of a solar-powered grid.

Using 40 years of solar data from the St. Louis region, Carlsson and Redner ran calculations over millions of hypothetical years to determine the optimal mix of power generation and storage to build a reliable grid that runs on renewable energy. Such a system is many years from reality, and Carlsson notes that a renewable grid in St. Louis would have to combine solar and wind power.

Still, the physicists found some room to be optimistic. Their analysis showed that, with only modest system improvements, a solar-powered grid could be extremely stable.

“Reliability improves exponentially if you increase either the generation capacity or the storage,” said Carlsson, a professor of physics in Arts & Sciences.

Storage capacity is crucial because sunshine can be in short supply during the winter in many parts of the country, including St. Louis. That means that any solar-powered energy system must include batteries that can supply energy on relatively dark days.

Building better batteries is an important mission for scientists at WashU and elsewhere. Advances in battery technology could certainly help revolutionize the power grid, but Carlsson and Redner’s calculations show that reducing the costs of solar panels could have a relatively greater impact on the efficiency of the overall system.

In St. Louis, the sun is reliable enough to power the grid for the great majority of the year, meaning that most of the energy will come directly from the power plant, not a battery. “But because the science of batteries offers more potential for game-changing discoveries, battery research should still be a priority,” he said.

Carlsson said the math of renewable energy points to another important lesson: The search for perfection might be counterproductive. A hypothetical system that runs exclusively on renewable solar and wind power would be significantly more expensive than a renewable system that used small amounts of natural gas as a backup, he said.

He estimated that, with current technology, a 100% renewable system that powered St. Louis could cost $130,000 per household. A system that was 95% or 99% renewable, however, could be in the range of $80,000 to $90,000.

“Extremely highly renewable systems are very expensive,” Carlsson said. “If we can get to 99% renewable in 10 years, versus 100% renewable in 30 years, we’d better figure out how to get to that 99%.”

Physicists at Delft University of Technology have built a new technology on a microchip by combining two Nobel Prize-winning techniques for the first time. This microchip could measure distances in materials at high precision—for example, underwater or for medical imaging.

Because the technology uses sound vibrations instead of light, it is useful for high-precision position measurements in opaque materials. The instrument could lead to new techniques to monitor the Earth’s climate and human health. The work is now published in Nature Communications.

Simple and low-power technology

The microchip mainly consists of a thin ceramic sheet that is shaped like a trampoline. This trampoline is patterned with holes to enhance its interaction with lasers and has a thickness about 1000 times smaller than the thickness of a hair. As a former Ph.D. candidate in Richard Norte’s lab, Matthijs de Jong studied the small trampolines to figure out what would happen if they pointed a simple laser beam at them.

The trampoline’s surface started vibrating intensely. By measuring the reflected laser light from the vibrating surface, the team noticed a pattern of vibrations in the shape of a comb that they hadn’t seen before. They realized that the trampoline’s comb-like signature functions as a ruler for precision measurements of distance.

This new technology could be used to measure positions in materials using sound waves. What makes it special is that it doesn’t need any precision hardware and is therefore easy to produce.

“It only requires inserting a laser, and nothing else. There’s no need for complex feedback loops or for tuning certain parameters to get our tech to operate properly. This makes it a very simple and low-power technology, that is much easier to miniaturize on a microchip,” Norte says. “Once this happens, we could really put these microchip sensors anywhere, given their small size.”

The new technology is based on two unrelated Nobel Prize-winning techniques, called optical trapping and frequency combs. Norte says, “The interesting thing is that both of these concepts are typically related to light, but these fields do not have any real overlap. We have uniquely combined them to create an easy-to-use microchip technology based on sound waves. This ease of use could have significant implications for how we measure the world around us.”

Overtones

When the researchers pointed a laser beam at the tiny trampoline, they realized that the forces that the laser exerted on it were creating overtone vibrations in the trampoline membranes. “These forces are called an optical trap, because they can trap particles in one spot using light. This technique won the Nobel Prize in 2018 and it allows us to manipulate even the smallest particles with extreme precision,” Norte explains.

“You can compare the overtones in the trampoline to particular notes of a violin. The note or frequency that the violin produces depends on where you place your finger on the string. If you touch the string only very lightly and play it with a bow, you can create overtones; a series of notes at higher frequencies. In our case, the laser acts as both the soft touch and the bow to induce overtone vibrations in the trampoline membrane.”

Bridging two breakthrough fields

“Optical frequency combs are used in labs around the world for very precise measurements of time, and to measure distances,” Norte says.

“They are so important to measurements in general that their invention was given a Nobel Prize in 2005. We have made an acoustic version of a frequency comb, made out of sound vibrations in the membrane instead of light. Acoustic frequency combs could for instance make position measurements in opaque materials, through which vibrations can propagate better than light waves.”

“This technology could for example be used for precision measurements underwater to monitor the Earth’s climate, for medical imaging and for applications in quantum technologies.”

Google on Tuesday invited people in the United States and Britain to test its AI chatbot, known as Bard, as it continues on its gradual path to catch up with Microsoft-backed ChatGPT.

Bard, ChatGPT and other similar artificial intelligence apps churn out essays, poems or computing code on command and have taken the world by storm as the biggest new thing in tech since the advent of the iPhone.

Google CEO Sundar Pichai told staff that after testing Bard with 80,000 Google employees, the chatbot would be tested with the public in the United States and Britain as a “first step” before going out to more countries in other languages.

“As more people start to use Bard and test its capabilities, they’ll surprise us,” Pichai said in a memo to staff seen by AFP.

“Things will go wrong. But the user feedback is critical to improving the product and the underlying technology,” added Pichai, who had faced some criticism within the company for rushing to catch up with Microsoft.

In the launch, people wishing to play with Bard can sign up on a waiting list at bard.google.com website, distinctly separate from the tech giant’s search engine.

“We’ve learned a lot so far by testing Bard, and the next critical step in improving it is to get feedback from more people,” Google vice presidents Sissie Hsiao and Eli Collins said in a blog post.

As exciting as chatbots can be, they have their faults, Hsiao and Collins cautioned.

‘Constantly learning’

Google has so far proceeded more carefully in its rollout of generative AI to consumers, in contrast to Microsoft’s choice to swiftly make the products available despite reports of problems.

ChatGPT’s OpenAI is backed by Microsoft, which earlier this year said it would finance the research company to the tune of billions of dollars.

Asked by AFP how its product was different from ChatGPT, Bard said that unlike its Microsoft-backed rival it was “able to access and process information from the real world through Google Search and keep my response consistent with search results.”

The bot also underlined that it was still “under development, while ChatGPT has been released to the public. This means that I am constantly learning and improving, while ChatGPT is likely to remain relatively unchanged.”

OpenAI recently released a long-awaited update of its AI technology that it said would be safer and more accurate than its predecessor.

Much of the new model’s firepower, known as GPT-4, is now available to the general public via ChatGPT Plus, OpenAI’s paid subscription plan and on an AI-powered version of Microsoft’s Bing search engine.

Microsoft has said that its quick adoption of generative AI has seen usage of its Bing search engine increase in recent weeks, but it is still a clear underdog to Google, which captures about 85 percent of the global search engine market.

© 2023 AFP

MechSE Associate Professor Kyle Smith and doctoral student Md Abdul Hamid recently published an article in the Journal of Power Sources.

Their study, “A bottom-up, multi-scale theory for transient mass transport of redox-active species through porous electrodes beyond the pseudo-steady limit,” demonstrates that conventional theory approaches underpredict the power capacity of flow batteries such as those used in electricity production from renewable energy sources.

“We have discovered a new means by which to understand how convection occurs inside of reactive porous media,” Smith said of their theory, which proposes introducing certain frequency-dependent transfer functions to up-scale mass transport occurring in the microscopic pores of electrodes. Although transfer functions are routinely used as mathematical tools in control theory, they have never before been applied in this context or derived in this manner.

The two began formulating their theory before the COVID-19 outbreak, making their publication a long-anticipated success. Their theory sheds new light on familiar mass and heat transfer principles—they introduced a spectral Sherwood number, which is a type of transfer function, to extend the film law of mass transfer to transient conditions. Similarly, a spectral Nusselt number extends Newton’s law of cooling for convection heat transfer. The two formulated the embedding of transfer functions into an up-scaled model to obtain the time-domain response of flow batteries.

“We have uncovered a new understanding of certain non-dimensional parameters that are ubiquitous in convection heat/mass transfer,” Smith said. “For the first time to our knowledge, we have extended these ideas from their conventional application in time-invariant, or steady state, settings to transient settings in a manner that accounts for changes in the microscopic dynamics that result from transient cycling.”

This work is also meaningful to chemical, civil, and petroleum engineering communities, which have explored approaches to understanding mass transfer in other porous materials. “Their approaches were not previously applied to the electrochemical systems that are the subject of our work,” Smith said. “However, we have developed a relatively straightforward approach to model these effects by using a formulation that starts from the detailed microstructure and up-scales its effects for use in macroscopic scale models.”

Indeed, the team’s theory demonstrates that flow batteries can be operated at higher than their limiting current for short periods of time, which suggests that cheaper and lighter batteries can be designed for these cycling conditions.

“These findings not only provide a better modeling approach for accurate prediction of an existing flow battery’s rate capability, but also provide guidelines toward more efficient designs, operating schemes, and materials,” Hamid said.

Smith and Hamid intend to apply their theory to different microstructures for porous electrodes for various energy and environmental devices using electrochemistry. Their next steps also include extending the theory beyond the range of conditions demonstrated in their publication.

Recognizing when senior citizens are at risk in the home or helping them find misplaced objects they presumed lost: The technology developed in the successful OMNICONNECT project can help people lead independent lives for longer. The researchers of Fraunhofer IZM have integrated a miniature radar system into an LED ceiling light that can track and recognize movement patterns and locate people or objects in a room.

Four radar modules are combined to ensure full 360° coverage. AI algorithms work through the collected data to identify whether a person in that range has suffered a fall, with the radar system being able to track more than 30 people in spaces of up to 1600 square feet with an angular resolution of 12°. And for added object detection capabilities, passive transponders were developed to work with the radar system.

Supported by the Ministry of Education and Research, the OMNICONNECT project has brought together researchers from the Fraunhofer Institute for Reliability and Microintegration IZM with partners from Berlin and Oldenburg.

Their mission: To develop a miniature radar system that can detect medical emergencies or other situations that require a caregiver’s intervention, while respecting the privacy of the users. By contrast to cameras or CCTV systems that record images, the system only tracks patterns of movement. It is integrated into a ceiling light, making it easy to install, unobtrusive, and easy to accept for the people living with it.

The system works with AI-supported radar modules and passive transponders that can be placed on different objects, thus for the first time enabling the tracking of movement and location with a single radar system. The transponders work as frequency-specific radar targets, with each resonating at a known frequency. This turns them into uniquely identifiable beacons that the system can scan for and whose precise location can be calculated by checking the time needed for the signal to bounce back.

The data is processed on site by a field-programmable gate array or FPGA, a tiny computing system with integrated processor. It shares the object and motion data with an AI-based system that can recognize movements and patterns, developed by the computer science researchers at the OFFIS Institute of the University of Oldenburg. To control the app and identify specific options, a special app interface was built by HFC Human-Factors-Consult GmbH.

The demonstration unit designed and constructed at Fraunhofer IZM has undergone live trials and proven its ability to detect an object’s position with an accuracy of five centimeters in a ten-meter range. The demonstrator is currently being used by the project partners in several possible use cases. The data it collects can be used to produce certain movement patterns of typical behaviors and, with enough meaningful data available, feed into possible assisted living applications or be used to recognize certain incidents. The position data could be used to check whether the detected person is feeling well or whether a medical or care intervention is indicated.

Large-scale, effective, and passive: these descriptions are aptly given to the integrated radiative and evaporative chiller (IREC), designed and tested by researchers at Tsinghua University in Beijing, China. The goal of this technology is to come up with an energetically affordable method of cooling to aid in the rising consumption of energy while still minimizing carbon emissions through the process.

“Energy scarcity is a universal challenge to global development. The demand for cooling has accounted for more than 10% of the total global electricity consumption, and the trend is increasing year by year,” said Liangti Qu, author of the paper and researcher at Tsinghua University.

In efforts to find a solution to a rising energy challenge, researchers worked to develop IREC. IREC works in tandem with a couple of partners, which include a polyacrylamide hydrogel layer and breathable, reflective fibers on the surface to reflect light. The hydrogel layer aids in speeding up the evaporation process as well as keeping the energy input from the sun minimized.

The reflective fibers can keep the energy from solar radiation from heating the water and are shown to be effective against high angles of light, making it effective during all parts of the day in all regions of the world.

The report was published in Nano Research Energy.

During their study, the researchers found that IREC can reduce the heat inside outdoor storage items by more than 9 ºC, making it an appealing option for outdoor cooling options.

“This technology can achieve cooling powers of over 700 W·m^–2, several times that of a single radiative cooling process. Besides, the working mode is compatible with the existing central heating equipment and can be used for central cooling in summer by supplying cold water. It promises to be a sustainable alternative to current cooling needs,” Qu said.

Additionally, it was shown that up to 69.2% of the heat consumed by IREC came from the environment. The IREC technology absorbs heat from the environment, thereby cooling it through evaporation. As if the technology wasn’t appealing enough in its efforts to be sustainable and cost-effective, the ability to set the IREC up on existing central heating equipment reduces the barrier to entry for those wishing for a more sustainable, energy-efficient cooling method.

The experiment also ran multiple tests to determine how well the radiative and evaporative cooling technique works under various conditions, such as indoor and outdoor use, and even use on the human body to aid in cooling.

On human skin, IREC mimics the sweat reaction humans have to keep cool under hot conditions and can assist in cooling the body by 13º C for over 12 hours. The wide application of this technology for not only commercial use but also personal use makes it even more appealing to researchers to continue to develop and streamline the process for wide-scale production.

Finding methods of cooling that are both cost and energy efficient will continue to be a challenge, especially to make them affordable and available on a large scale. Ideally, once the prototype is streamlined and optimized, the researchers want to see this integrated cooling technology commercially available for use in “green” buildings and industrial storage facilities.

Provided by
Tsinghua University Press

Food delivery platform Just Eat Takeaway unveiled plans Tuesday to axe more than 1,700 mostly courier jobs in Britain, as it slashes costs in the wake of huge annual losses.

The UK business “is reorganising and simplifying its delivery operation as part of the ongoing goal of improving efficiency”, it said in a statement emailed to AFP.

“As part of this process we have proposed to transition away from the worker model for couriers” in Britain, it added.

Just Eat Takeaway said its UK division will stop employing its own couriers—and instead will only use self-employed gig economy workers.

Approximately 170 staff in its UK operations team will also be affected by the overhaul, but some could be redeployed.

Just Eat Takeaway had revealed earlier this month that acquisition writedowns, the souring economic climate and rising interest rates sparked a massive loss of about 5.7 billion euros ($6.1 billion) last year.

The Amsterdam-based company was created in 2020 after Dutch online service Takeaway.com gobbled up Britain’s Just Eat, and business subsequently boomed on the back of the COVID pandemic-fuelled surge in home delivery, which has since subsided.

The group has also put Grubhub up for sale as it seeks to focus on Europe, having already slashed the value of the US subsidiary it bought for $7.3 billion in 2020.

© 2023 AFP

Concrete is the most used material in the construction industry and dates to the Roman Empire. Engineers at the University of Pittsburgh are now reimagining its design for the 21st century.

New research introduces metamaterial concrete for the development of smart civil infrastructure systems. The paper, “Multifunctional Nanogenerator-Integrated Metamaterial Concrete Systems for Smart Civil Infrastructure,” presents a new concept for lightweight and mechanically-tunable concrete systems that have integrated energy harvesting and sensing functionality.

“Modern society has been using concrete in construction for hundreds of years, following its original creation by the ancient Romans,” said Amir Alavi, assistant professor of civil and environmental engineering at Pitt, who is the corresponding author on the study. “Massive use of concrete in our infrastructure projects implies the need for developing a new generation of concrete materials that are more economical and environmentally sustainable, yet offer advanced functionalities. We believe that we can achieve all of these goals by introducing a metamaterial paradigm into the development of construction materials.”

Alavi and his team have previously developed self-aware metamaterials and explored their use in applications like smart implants.

This study introduces the use of metamaterials in the creation of concrete, making it possible for the material to be specifically designed for its purpose. Attributes like brittleness, flexibility and shapeability can be fine-tuned in the creation of the material, enabling builders to use less of the material without sacrificing strength or longevity.

“This project presents the first composite metamaterial concrete with super compressibility and energy harvesting capability,” said Alavi. “Such lightweight and mechanically tunable concrete systems can open a door to the use of concrete in various applications such as shock absorbing engineered materials at airports to help slow runaway planes or seismic base isolation systems.”

Not only that, but the material is capable of generating electricity. While it cannot produce enough electricity to send power to the electrical grid, the generated signal will be more than enough to power the roadside sensors. The electrical signals self-generated by the metamaterial concrete under mechanical excitations can also be used to monitor damage inside the concrete structure or to monitor earthquakes while reducing their impact on buildings.

Eventually, these smart structures may even power chips embedded inside roads to help self-driving cars navigate on highways when GPS signals are too weak or LIDAR is not working.

The material is composed of reinforced auxetic polymer lattices embedded in a conductive cement matrix. The composite structure induces contact-electrification between the layers when triggered mechanically. The conductive cement, which is enhanced with graphite powder, serves as the electrode in the system. Experimental studies show that the material can compress up to 15% under cyclic loading and produce 330 μW of power.

The research team is partnering with the Pennsylvania Department of Transportation (PennDOT) through the IRISE Consortium at Pitt to develop this metamaterial concrete for use on Pennsylvania roads.

The paper, “Multifunctional Nanogenerator-Integrated Metamaterial Concrete Systems for Smart Civil Infrastructure,” was published in Advanced Materials.

A recent study that examined the relationship between artificial intelligence (AI) and law enforcement underscores both the need for law enforcement agencies to be involved in the development of public policies regarding AI—such as regulations governing autonomous vehicles—and the need for law enforcement officers to better understand the limitations and ethical challenges of AI technologies.

“Law enforcement agencies have a crucial role to play in implementing public policies related to AI technologies,” says Veljko Dubljević, corresponding author of the study and an associate professor of science, technology and society at North Carolina State University.

“For example, officers will need to know how to proceed if they pull over a vehicle being driven autonomously for a traffic violation. For that matter, they will need to know how to pull over a vehicle being driven autonomously. Because of their role in maintaining public order, it’s important for law enforcement to have a seat at the table in crafting these policies.”

“In addition, there are a number of AI-powered technologies that are already in use by law enforcement agencies that are designed to help them prevent and respond to crime,” says Ronald Dempsey, first author of the study and a former graduate student at NC State. “These range from facial recognition technologies to technologies designed to detect gunshots and notify relevant law enforcement agencies.”

“However, our study suggests that many officers do not understand how these technologies work, which makes it difficult or impossible for them to appreciate the limitations and ethical risks of those technologies. And that can pose significant problems for both law enforcement and the public.”

For this study, the researchers conducted in-depth interviews with 20 law enforcement professionals who work in North Carolina. The interviews addressed a range of issues, including the values and qualities that the study participants felt were critical for law enforcement officers.

While there was no consensus across a majority of study participants, there were several characteristics that cropped up repeatedly as important qualities for a law enforcement professional, with integrity, honesty and empathy being cited most often.

“Understanding what law enforcement deems to be desirable characteristics in officers is valuable, because these characteristics can inform the development of responsible design guidelines for AI technologies that law enforcement will use,” Dempsey says.

“Design guidelines can be used to inform AI decision-making, and it is easier for end users to work with AI tools if the values guiding AI decisions are consistent—or at least not in conflict—with the values of the end users,” says Dubljević.

The researchers also asked study participants about their views on AI in general, as well as existing and emerging AI technologies.

“We found that study participants were not familiar with AI, or with the limitations of AI technologies,” says Jim Brunet, co-author of the study and director of NC State’s Public Safety Leadership Initiative. “This included AI technologies that participants had used on the job, such as facial recognition and gunshot detection technologies. However, study participants expressed support for these tools, which they felt were valuable for law enforcement.”

The study participants also expressed concern about the future of autonomous vehicles, and what challenges they may pose to the law enforcement community.

“However, study participants did say that they would welcome public use of autonomous vehicles if that would reduce car accidents,” says Dubljević. “Specifically, the participants welcomed the idea of spending less time responding to vehicle accidents, which would allow them to focus on addressing crime.”

“There are always dangers when law enforcement adopts technologies that were not developed with law enforcement in mind,” says Brunet. “This certainly applies to AI technologies such as facial recognition. As a result, it’s critical for law enforcement officials to have some training in the ethical dimensions surrounding the use of these AI technologies. For example, where a law enforcement agency chooses to deploy AI tools will affect which portions of the public are subject to additional scrutiny.”

“It’s also important to understand that AI tools are not foolproof,” says Dubljević. “AI is subject to limitations. And if law enforcement officials don’t understand those limitations, they may place more value on the AI than is warranted—which can pose ethical challenges in itself.”

The paper is published in the journal Applied Sciences.

Unmanned aerial vehicles (UAVs), also known as drones, can help humans to tackle a variety of real-world problems; for instance, assisting them during military operations and search and rescue missions, delivering packages or exploring environments that are difficult to access. Conventional UAV designs, however, can have some shortcomings that limit their use in particular settings.

For instance, some UAVs might be unable to land on uneven terrains or pass through particularly narrow gaps, while others might consume too much power or only operate for short amounts of time. This makes them difficult to apply to more complex missions that require reliably moving in changing or unfavorable landscapes.

Researchers at Zhejiang University have recently developed a new unmanned, wheeled and hybrid vehicle that can both roll on the ground and fly. This unique system, introduced in a paper pre-published on arXiv, is based on a unicycle design (i.e., a cycling vehicle with a single wheel) and a rotor-assisted turning mechanism.

“Roller-Quadrotor is a novel hybrid terrestrial and aerial quadrotor that combines the elevated maneuverability of the quadrotor with the lengthy endurance of the ground vehicle,” Zhi Zheng, Jin Wang and their colleagues wrote in their paper. “Flying is achieved through a quadrotor configuration, and four actuators providing thrust. Rolling is supported by unicycle-driven and rotor-assisted turning structure. During terrestrial locomotion, the vehicle needs to overcome rolling and turning resistance, thus saving energy compared to flight mode.”

The hybrid terrestrial and aerial vehicle created by Zheng, Wang and their colleagues is a so-called quadrotor, which is an aircraft based on rotary wings that can hover above ground and fly. As it is based on a unicycle structure, it can also move on the ground on various terrains and pass through narrow gaps.

“This work overcomes the challenging problems of general rotorcraft, reduces energy consumption and allows movement through special terrains, such as narrow gaps,” the researchers wrote in their paper. “It also solves the obstacle avoidance challenge faced by terrestrial robots by flying.”

In their paper, Zheng, Wang and their colleagues present their vehicle’s design along with a series of models and controllers that allow it to roll, fly, and seamlessly transition between these two modes of operation. They also outline the results of a series of experiments, where a prototype of their vehicle was tested in an environment monitored by cameras and motion capture sensors.

“We design the models and controllers for the vehicle,” Zheng, Wang and their colleagues wrote in their paper. “The experiment results show that it can switch between aerial and terrestrial locomotion, and be able to safely pass through a narrow gap half the size of its diameter. Besides, it is capable of rolling a distance approximately 3.8 times as much as flying or operating about 42.2 times as lengthy as flying.”

The hybrid vehicle presented in this recent paper could soon be tested and evaluated in a wider range of environments, to further validate its performance. Initial results gathered by Zheng, Wang and their colleagues suggest that the vehicle could eventually be used to tackle complex real-world missions that entail moving on tricky terrains, entering narrow passages and operating for longer periods of time.

In their next studies, the researchers plan to enhance their design further, for instance by improving the accuracy of the models they created and introducing more advanced control algorithms. This could in turn make the vehicle’s transition from its rolling to flying modes smoother, while also improving its navigation capabilities.

“We are also considering structural optimization and weight reduction, to further improve the energy consumption performance,” the researchers concluded in their paper. “Furthermore, we will use planning algorithms to enhance vehicle mobility.”

© 2023 Science X Network