A team of researchers has created a new class of titanium alloys that are strong and not brittle under tension, by integrating alloy and 3D-printing process designs.

The breakthrough, published in the journal Nature, could help extend the applications of titanium alloys, improve sustainability and drive innovative alloy design.

Their discovery holds promise for a new class of more sustainable high-performance titanium alloys for applications in aerospace, biomedical, chemical engineering, space and energy technologies.

RMIT University and the University of Sydney led the innovation, in collaboration with Hong Kong Polytechnic University and the company Hexagon Manufacturing Intelligence in Melbourne.

Lead researcher, Ma Qian a professor from RMIT, said the team embedded circular economy thinking in their design, creating great promise for producing their new titanium alloys from industrial waste and low-grade materials.

“Reusing waste and low-quality materials has the potential to add economic value and reduce the high carbon footprint of the titanium industry,” said Qian from RMIT’s Center for Additive Manufacturing in the School of Engineering.

What type of titanium alloys has the team made?

The team’s titanium alloys consist of a mixture of two forms of titanium crystals, called alpha-titanium phase and beta-titanium phase, each corresponding to a specific arrangement of atoms.

This class of alloys has been the backbone of the titanium industry. Since 1954, these alloys have been produced primarily by adding aluminum and vanadium to titanium.

The research team investigated the use of oxygen and iron—two of the most powerful stabilizers and strengtheners of alpha- and beta-titanium phases—which are abundant and inexpensive.

Two challenges have hindered the development of strong and ductile alpha-beta titanium-oxygen-iron alloys through the conventional manufacturing processes, Qian said.

“One challenge is that oxygen—described colloquially as ‘the kryptonite to titanium’—can make titanium brittle, and the other is that adding iron could lead to serious defects in the form of large patches of beta-titanium.”

The team used Laser Directed Energy Deposition (L-DED), a 3D printing process suitable for making large, complex parts, to print their alloys from metal powder.

“A key enabler for us was the combination of our alloy design concepts with 3D-printing process design, which has identified a range of alloys that are strong, ductile and easy to print,” Qian said.

The attractive properties of these new alloys that can rival those of commercial alloys are attributed to their microstructure, the team says.

“This research delivers a new titanium alloy system capable of a wide and tunable range of mechanical properties, high manufacturability, enormous potential for emissions reduction and insights for materials design in kindred systems,” said co-lead researcher University of Sydney Pro-Vice-Chancellor Professor Simon Ringer.

“The critical enabler is the unique distribution of oxygen and iron atoms within and between the alpha-titanium and beta-titanium phases.

“We’ve engineered a nanoscale gradient of oxygen in the alpha-titanium phase, featuring high-oxygen segments that are strong, and low-oxygen segments that are ductile allowing us to exert control over the local atomic bonding and so mitigate the potential for embrittlement.”

What are the potential applications of the research findings?

Lead author Dr. Tingting Song, RMIT Vice-Chancellor’s Research Fellow, said the team is “at the start of a major journey, from the proof of our new concepts here, towards industrial applications.”

“There are grounds to be excited—3D printing offers a fundamentally different way of making novel alloys and has distinct advantages over traditional approaches,” she said.

“There’s a potential opportunity for industry to reuse waste sponge titanium-oxygen-iron alloy, ‘out-of-spec’ recycled high-oxygen titanium powders or titanium powders made from high-oxygen scrap titanium using our approach.”

Co-lead author Dr. Zibin Chen, who joined Hong Kong Polytechnic University from the University of Sydney in the later stages of the collaboration, said the research had broader implications.

“Oxygen embrittlement is a major metallurgical challenge not only for titanium, but also for other important metals such as zirconium, niobium and molybdenum and their alloys,” he said.

“Our work may provide a template to mitigate these oxygen embrittlement issues through 3D printing and microstructure design.”

The team’s work benefited from sustained, targeted investment in research infrastructure from national and state governments and from universities, Ringer said.

“In many ways, this work showcases the power of Australia’s national collaborative research infrastructure strategy and sets the scene for extending this strategy into the realm of advanced manufacturing,” he said.

The team’s research paper, “Strong and ductile titanium-oxygen-iron alloys by additive manufacturing,” is published in Nature.

An editorial on the team’s work, “Designer titanium alloys created using 3D printing,” is also published in Nature.

Data-driven algorithms supercharged the advertising industry by enabling precisely targeted campaigns, but new AI tools may be about to shake the sector once again.

Some brands are dipping their toes in the AI waters, like Coca-Cola, which has invited people to create AI works using “iconic creative assets from the Coca-Cola digital archives”.

Others are using it to create a social media buzz—fashion firm Stradivarius recently pushed out AI images based on one of its collections.

But the full force of the AI revolution may be felt most keenly in the engine room of the ad industry—the agencies who conceive and design the campaigns.

“We’re only at the beginning,” said Fernando Pascual, vice-president of design at Spanish company Seedtag.

His firm specializes in “contextual” advertising, which they claim will enable digital ads to blend in with the website where they appear.

So a car ad might show the vehicle driving through a glass and steel cityscape on a business-orientated website, but the same car might be seen cruising past peaceful suburban gardens on a family-friendly website.

“The main element of advertising is still anchored in reality,” he told AFP.

“We’re just helping our clients to be more relevant.”

Seedtag is far from the only ad agency promoting its AI chops.

But photographers and models are among those left wondering about their future livelihoods.

‘Uproar’

French lingerie firm Undiz recently found itself at the center of the debate.

Billboards in brilliant blue with eerily beautiful models gliding underwater in the firm’s swimwear have appeared across France in recent weeks.

Only, there were no real people in these posters.

The models were created by an ad agency using image generator Midjourney, with real images of the swimming costumes added later.

“We wanted to achieve a slightly dreamlike, intriguing result,” Undiz director Isolde Andouard told AFP.

Andouard admitted that the campaign had caused “uproar” among models and photographers.

Thomas Serer, a popular French content creator and photographer, wrote on Twitter that he was a fan of AI but in this case “using AI adds zero value” apart from allowing the firm to save money.

Andouard was quick to deny the approach was simply about cutting costs, saying the AI campaign was rolled out alongside traditional photos.

‘Non-event’

The reaction to the Undiz campaign suggests the path to AI domination will be far from smooth.

And they are not the only company to have received criticism.

Jeans brand Levi’s trumpeted a partnership with Dutch studio Lalaland.ia in March with the promise of using AI models to boost diversity on its online shop.

After an outcry, the firm put out another statement saying its announcement “did not properly represent certain aspects of the program” and promised to continue working with models and photographers.

There are plenty who doubt that such upfront uses will ever really go industry-wide.

Olivier Bomsel, an economist specializing in intellectual property and advertising, said the arrival of AI-manipulated images was a “non-event” and amounted to just a new kind of digital editing.

And as AI tools get more widespread, he said, the people whose images provide the training data will be able to claim fees that will eventually “cost as much as using a model“.

And the arrival of AI behemoths Meta and Google into the space is sending heads spinning.

Both firms announced in May a series of simplified AI tools that promise to allow anyone to design ad campaigns just using simple phrases as prompts.

It remains to be seen whether this will give ad agencies a shiny new plaything—or torpedo their business models entirely.

© 2023 AFP

Japan on Wednesday passed a law allowing nuclear reactors to operate beyond 60 years, as it tries to reinvigorate the sector to meet energy challenges and climate targets.

The bill intends to “establish an electricity supply system that will achieve a carbon-free society”, a parliament spokesman told AFP.

Under the new rules, the age cap technically remains 60 years but exceptions are allowed for reactors that have had to pause operations for “unforeseeable” reasons.

Those might include changes to safety guidelines, or provisional injunctions by a court.

The new rules allow operators to exclude periods of shutdown when calculating the total years of operation.

However, operators require approval from Japan’s nuclear safety watchdog for the exemption, and the law also includes measures intended to strengthen safety checks at aging reactors.

The government wants to “ensure a stable supply of electricity while promoting the use of carbon-free electricity resources,” Japan’s ministry of economy, trade and industry said in a statement.

The move comes as Japan’s government looks to reinvigorate a nuclear sector that was taken offline after the 2011 Fukushima disaster caused by a deadly tsunami.

Most of Japan’s nuclear reactors remain out of action today, but the global energy crisis has reopened debate on the subject and polls show that public views on nuclear power are softening.

© 2023 AFP

An optical fiber about the thickness of a human hair can now carry the equivalent of more than 10 million fast home internet connections running at full capacity.

A team of Japanese, Australian, Dutch, and Italian researchers has set a new speed record for an industry standard optical fiber, achieving 1.7 Petabits over a 67km length of fiber. The fiber, which contains 19 cores that can each carry a signal, meets the global standards for fiber size, ensuring that it can be adopted without massive infrastructure change. And it uses less digital processing, greatly reducing the power required per bit transmitted.

Macquarie University researchers supported the invention by developing a 3D laser-printed glass chip that allows low loss access to the 19 streams of light carried by the fiber and ensures compatibility with existing transmission equipment.

The fiber was developed by the Japanese National Institute of Information and Communications Technology (NICT, Japan) and Sumitomo Electric Industries, Ltd. (SEI, Japan) and the work was performed in collaboration with the Eindhoven University of Technology, University of L’Aquila, and Macquarie University.

All the world’s internet traffic is carried through optical fibers which are each 125 microns thick (comparable to the thickness of a human hair). These industry standard fibers link continents, data centers, mobile phone towers, satellite ground stations and our homes and businesses.

Back in 1988, the first subsea fiber-optic cable across the Atlantic had a capacity of 20 Megabits or 40,000 telephone calls, in two pairs of fibers. Known as TAT 8, it came just in time to support the development of the World Wide Web. But it was soon at capacity.

The latest generation of subsea cables such as the Grace Hopper cable, which went into service in 2022, carries 22 Terabits in each of 16 fiber pairs. That’s a million times more capacity than TAT 8, but it’s still not enough to meet the demand for streaming TV, video conferencing and all our other global communication.

“Decades of optics research around the world has allowed the industry to push more and more data through single fibers,” says Dr. Simon Gross from Macquarie University’s School of Engineering. “They’ve used different colors, different polarizations, light coherence and many other tricks to manipulate light.”

Most current fibers have a single core that carries multiple light signals. But this current technology is practically limited to only a few Terabits per second due to interference between the signals.

“We could increase capacity by using thicker fibers. But thicker fibers would be less flexible, more fragile, less suitable for long-haul cables, and would require massive reengineering of optical fiber infrastructure,” says Dr. Gross.

“We could just add more fibers. But each fiber adds equipment overhead and cost and we’d need a lot more fibers.”

To meet the exponentially growing demand for movement of data, telecommunication companies need technologies that offer greater data flow for reduced cost.

The new fiber contains 19 cores that can each carry a signal.

“Here at Macquarie University, we’ve created a compact glass chip with a wave guide pattern etched into it by a 3D laser printing technology. It allows feeding of signals into the 19 individual cores of the fiber simultaneously with uniform low losses. Other approaches are lossy and limited in the number of cores,” says Dr. Gross.

“It’s been exciting to work with the Japanese leaders in optical fiber technology. I hope we’ll see this technology in subsea cables within five to 10 years.”

Another researcher involved in the experiment, Professor Michael Withford from Macquarie University’s School of Mathematical and Physical Sciences, believes this breakthrough in optical fiber technology has far-reaching implications.

“The optical chip builds on decades of research into optics at Macquarie University,” says Professor Withford. “The underlying patented technology has many applications including finding planets orbiting distant stars, disease detection, even identifying damage in sewage pipes.”

The paper is published in the proceedings of the Optical Fiber Communication Conference (OFC) 2023.

Transportation accounts for roughly one-third of U.S. greenhouse gas emissions, and adoption of electric vehicles is seen by many experts in government and the private sector as a vital tool in efforts to reduce carbon emissions. Roughly a decade ago, EVs accounted for a tiny fraction of overall car sales. As of March 2023, they make up 7% of new sales

“What changed between then and now?” asks Kenneth Gillingham, professor of environmental and energy economics at the Yale School of the Environment. “Was it that consumers suddenly decided they like EVs much more, or was it that EVs themselves got a lot better?”

New research by Gillingham, published in Proceedings of the National Academy of Sciences, finds that recent adoption of EVs is driven overwhelmingly by technological advances, while general consumer preferences for EVs has changed little. Improvements like increased battery range, faster charging, falling prices, and reduced operating costs have made EVs an enticing option alongside their gas-powered counterparts. (Range proved particularly important, with cars that can travel 300 miles or more on a single charge essentially as attractive as comparable gas cars in consumers’ minds, the study reveals.)

Gillingham and Carnegie Mellon University co-authors surveyed about 1,600 people who had intentions of purchasing a car or SUV within the next two years, or who had purchased one within the prior year. Respondents were shown 15 sets of three vehicles with various attributes—some gasoline powered, some electric, some hybrid—and asked which one they would choose. The results from this survey were matched with results from a similar survey conducted in 2012 and 2013, and from this comparison the researchers were able to discern how much new adoption of EVs was due to consumer preferences and how much was due to technological advancements. This prompted another inquiry.

“The big question is what happens next,” Gillingham says.

To answer this, the researchers paired the consumer adoption trends that they revealed with forecasted improvements in vehicle technology and predicted new EV offerings. Gillingham notes that there are more than 100 new EV models slated to become available globally in the next three to four years. Taken together, this information suggests that EVs could account for 40-60% of all new cars and SUVs sold by 2030. In short, it is possible that EVs could dominate the market only seven years from now.

For policymakers, the authors note, the findings suggest that rapid change and ambitious goals might be achievable. Gillingham cites one of the U.S. Environmental Protection Agency’s recently proposed rules limiting greenhouse gas emissions for cars and small trucks, that if adopted, could lead to EVs comprising about two-thirds of all new vehicle sales by 2032.

“Our study doesn’t say by any means that it is going to happen, but it isn’t beyond the realm of possibility. We really could have EVs making up a majority of all cars sold by 2030,” Gillingham says.

The implications also are clear for manufacturers—and many have already responded to evident shifts in the market. GM has announced plans to sell only EVs by 2035. Lexus, under Toyota, has announced the same goal. The findings from this research, Gillingham suggests, support the deep investment required by such a transition.

“Vehicle manufacturers who are leaders in the EV space will take comfort in what we’ve found,” he says. “Manufacturers who are laggards might want to think carefully about what their plans are.”

It is the year 2035. In a world facing climate catastrophe, the human enterprise is powered by fields of wind farms, with turbine blades made from fast-growing grasses and the roots of a million-year-old fungus.

It may sound like a scene from a climate-fiction movie, but polymer composites expert Valeria La Saponara, a professor in the UC Davis Department of Mechanical and Aerospace Engineering, has a vision to develop compostable, ecologically sound wind turbine blades from bamboo and mycelium, the fungal rootlike system that bears mushrooms.

La Saponara, co-principal investigator Michele Barbato in the Department of Civil and Environmental Engineering, and a diverse team of students and researchers in the Advanced Composites Research, Engineering and Science laboratory are testing a prototype on campus.

The environmental challenge of wind turbine blade disposal

Wind is one of the fastest growing sources of renewable energy in California and around the globe. It is a key part of California’s path to carbon neutrality by 2045. China, which accounts for more than half of global wind power, is planning to build a wind farm that could power 13 million homes by 2025 as it works toward its 2060 net-zero goal.

The expanding role of wind is largely good news. But as this key source of renewable energy grows, an environmentally sound solution is needed for the exponentially growing number of wind blades bound for landfills. Wind turbine blades are huge: The average rotor diameter in the U.S. in 2021 was 418 feet, so a single blade is almost as big as a Boeing 747’s wingspan. Designed to be resilient against heavy winds and weather conditions, the blades have a lifespan of about 20 years before they are retired or replaced. Most are constructed using a composite structure of fiberglass/epoxy built on top of balsa wood, which adds stability and flexibility. Recycling options are very limited, costly, and incur the additional carbon footprint impacts of transportation.

Most wind turbine blades end up in landfills. In the U.S. alone, more than 2 million tons of decommissioned blades are projected to be sent to landfills by 2050 according to a recent study; globally, the mass of all the blades expected to be retired by 2050 may be as high as 43 million metric tons. The use of balsa wood is an additional, devastating ecological impact. Rapid growth in the wind power industry has caused overlogging in the Ecuadorean Amazon rain forest, resulting in unchecked deforestation and societal harm to Indigenous communities in the region. Some manufacturers have been switching to PET plastics, adding to the millions of tons of PET waste in the environment.

Designing compostable wind turbine blades

For La Saponara, wind blade pollution is an urgent problem.

“We want to have clean energy, but clean energy cannot pollute the environment, and it can’t cause deforestation,” La Saponara said. “If we’re doing clean energy, it’s not to deforest the Amazon rainforest. We want to be good citizens for everybody.”

La Saponara envisions a compostable wind turbine blade built with woven bamboo, mycelium and biomass from the agricultural waste from California’s Central Valley in place of fiberglass and balsa wood. She first began working with mycelium in 2019, when she sought an alternative to the fossil-based plastics of bike helmet liners. Mycelium is an amazingly versatile substance, and La Saponara’s lab has been researching possibilities to leverage it as a low-carbon emission, low-toxicity, compostable alternative to non-degradable materials like polyurethane and acrylic.

Scaling up to a project as large and complex as wind turbine blades is a next-level move involving a highly collaborative group.

“The project is mushrooming,” La Saponara joked. “Creating this design requires work from multiple disciplines.”

In addition to co-principal investigator Barbato, who will support structural development, and research engineer Shuhao Wan, the project includes a diverse group of student researchers in engineering and design.

Combining sustainable materials: Bamboo and mycelium

As luck would have it, La Saponara has a highly multidisciplinary researcher in her team, who is also a skilled bamboo artisan. Shuhao Wan, the lab’s instrumentation and design research engineer, has worked with bamboo as a hobby, crafting model ships in bottles. Wan is testing different ways to weave the bamboo reeds.

Meanwhile, the team is working on optimizing media for growing and attaching the mycelium layer. Mycelium is an amazing material because it can be grown where it’s going to be used—as long as the conditions are right. The fungal mass can thrive in waste streams from coffee grounds to discarded plastics, with its feedstock influencing its properties. But mycelium doesn’t eat everything, and naturally anti-fungal bamboo is not on the menu. The team is testing to incorporate post-consumer textile waste, which may offer the bonus outcome of growing the mycelium using waste otherwise bound for landfill.

Testing mycelium-bamboo wind blades

The team recently built a prototype to begin testing.

“We want to do structural testing to find out how fast a rotation we can have, how much power we can generate,” La Saponara said.

The mycelium-bamboo composite will replace blades on a commercial 1-kilowatt turbine set up near the STEEL Lab, part of the Western Cooling Efficiency Center, away from central campus. La Saponara said they also will test the resilience of these blades, making sure they can withstand 85-mile-per-hour winds.

“Once we have the proof of concept for 1 kilowatt, which is a reasonable amount of power, then we can start working with companies for the commercialization of this concept for distributed energy applications,” La Saponara said.

These are early days toward the eventual goal of scaling the blades for global use. In fact, the blades could help in areas affected by natural disasters, where energy solutions are needed quickly, and wind power could be paired up with solar panels.

“What we’re doing right now doesn’t work anymore,” she said. “We’re at a tipping point in the environment, and our next generation are the ones who will pay the highest price. Ultimately, there’s no way we can talk about environmental engineering without talking about environmental justice.”

A plentiful supply of clean energy is lurking in plain sight. It is the hydrogen we can extract from water (H₂O) using renewable energy. Scientists are seeking low-cost methods for producing clean hydrogen from water to replace fossil fuels, as part of the quest to combat climate change.

Hydrogen can power vehicles while emitting nothing but water. Hydrogen is also an important chemical for many industrial processes, most notably in steel making and ammonia production. Using cleaner hydrogen is highly desirable in those industries.

A multi-institutional team led by the U.S. Department of Energy’s (DOE) Argonne National Laboratory has developed a low-cost catalyst for a process that yields clean hydrogen from water. Other contributors include DOE’s Sandia National Laboratories and Lawrence Berkeley National Laboratory, as well as Giner Inc.

“A process called electrolysis produces hydrogen and oxygen from water and has been around for more than a century,” said Di-Jia Liu, senior chemist at Argonne. He also holds a joint appointment in the Pritzker School of Molecular Engineering at the University of Chicago.

Proton exchange membrane (PEM) electrolyzers represent a new generation of technology for this process. They can split water into hydrogen and oxygen with higher efficiency at near room temperature. The reduced energy demand makes them an ideal choice for producing clean hydrogen by using renewable but intermittent sources, such as solar and wind.

This electrolyzer runs with separate catalysts for each of its electrodes (cathode and anode). The cathode catalyst yields hydrogen, while the anode catalyst forms oxygen. A problem is that the anode catalyst uses iridium, which has a current market price of around $5,000 per ounce. The lack of supply and high cost of iridium pose a major barrier for widespread adoption of PEM electrolyzers.

The main ingredient in the new catalyst is cobalt, which is substantially cheaper than iridium. “We sought to develop a low-cost anode catalyst in a PEM electrolyzer that generates hydrogen at high throughput while consuming minimal energy,” Liu said. “By using the cobalt-based catalyst prepared by our method, one could remove the main bottleneck of cost to producing clean hydrogen in an electrolyzer.”

Giner Inc., a research and development company working toward commercialization of electrolyzers and fuel cells, evaluated the new catalyst using its PEM electrolyzer test stations under industrial operating conditions. The performance and durability far exceeded that of competitors’ catalysts.

Important to further advancing the catalyst performance is understanding the reaction mechanism at the atomic scale under electrolyzer operating conditions. The team deciphered critical structural changes that occur in the catalyst under operating conditions by using X-ray analyses at the Advanced Photon Source (APS) at Argonne. They also identified key catalyst features using electron microscopy at Sandia Labs and at Argonne’s Center for Nanoscale Materials (CNM). The APS and CNM are both DOE Office of Science user facilities.

“We imaged the atomic structure on the surface of the new catalyst at various stages of preparation,” said Jianguo Wen, an Argonne materials scientist.

In addition, computational modeling at Berkeley Lab revealed important insights into the catalyst’s durability under reaction conditions.

The team’s achievement is a step forward in DOE’s Hydrogen Energy Earthshot initiative, which mimics the U.S. space program’s “Moon Shot” of the 1960s. Its ambitious goal is to lower the cost for green hydrogen production to one dollar per kilogram in a decade. Production of green hydrogen at that cost could reshape the nation’s economy. Applications include the electric grid, manufacturing, transportation and residential and commercial heating.

“More generally, our results establish a promising path forward in replacing catalysts made from expensive precious metals with elements that are much less expensive and more abundant,” Liu noted.

This research was published on May 11 in Science.

The field of transformation optics has flourished over the past decade, allowing scientists to design metamaterial-based structures that shape and guide the flow of light. One of the most dazzling inventions potentially unlocked by transformation optics is the invisibility cloak—a theoretical fabric that bends incoming light away from the wearer, rendering them invisible. Interestingly, such illusions are not restricted to the manipulations of light alone.

Many of the techniques used in transformation optics have been applied to sound waves, giving rise to the parallel field of transformation acoustics. In fact, researchers have already made substantial progress by developing the “acoustic cloak”, the analog of the invisibility cloak for sounds. While research on acoustic illusion has focused on the concept of masking the presence of an object, not much progress has been made on the problem of location camouflaging.

The concept of an acoustic source-shifter utilizes a structure that makes the location of the sound source appear different from its actual location. Such devices capable of “acoustic location camouflaging” could find applications in advanced holography and virtual reality. Unfortunately, the nature of location camouflaging has been scarcely studied, and the development of accessible materials and surfaces that would provide a decent performance has proven challenging.

Against this backdrop, Professor Garuda Fujii, affiliated with the Institute of Engineering and Energy Landscape Architectonics Brain Bank (ELab²) at Shinshu University, Japan, has now made progress in developing high-performance source-shifters. In a recent study published in the Journal of Sound and Vibration, Prof. Fujii presented an innovative approach to designing source-shifter structures out of acrylonitrile butadiene styrene (ABS), an elastic polymer commonly used in 3D printing.

Prof. Fujii’s approach is centered around a core concept: inverse design based on topology optimization. The numerical approach builds on the reproduction of pressure fields (sound) emitted by a virtual source, i.e., the source that nearby listeners would mistakenly perceive as real.

Next, the pressure fields emitted by the actual source are manipulated to camouflage the location and make it sound as if coming from a different location in space. This can be achieved with the optimum design of a metastructure that, by the virtue of its geometry and elastic properties, minimizes the difference between the pressure fields emitted from the actual and virtual sources.

Utilizing this approach, Prof. Fujii implemented an iterative algorithm to numerically determine the optimal design of ABS resin source-shifters according to various design criteria. His models and simulations had to account for the acoustic-elastic interactions between fluids (air) and solid elastic structures, as well as the actual limitations of modern manufacturing technology.

The simulation results revealed that the optimized structures could reduce the difference between the emitted pressure fields of the masked source and those of a bare source at the virtual location to as low as 0.6%. “The optimal structure configurations obtained via topology optimization exhibited good performances at camouflaging the actual source location despite the simple composition of ABS that did not comprise complex acoustic metamaterials,” remarks Prof. Fujii.

To shed more light on the underlying camouflaging mechanisms, Prof. Fujii analyzed the importance of the distance between the virtual and actual sources. He found that a greater distance did not necessarily degrade the source-shifter’s performance. He also investigated the effect of changing the frequency of the emitted sound on the performance as the source-shifters had been optimized for only one target frequency. Finally, he explored whether a source-shifter could be topologically optimized to operate at multiple sound frequencies.

While his approach requires further fine-tuning, the findings of this study will surely help advance illusion acoustics. He concludes, “The proposed optimization method for designing high-performance source-shifters will help in the development of acoustic location camouflage and the advancement of holography technology.”

Provided by
Shinshu University

With summer temperatures soaring, the specter of water scarcity looms large. As a possible solution to increase the availability of clean, potable water, researchers at the Indian Institute of Science (IISc) have developed a novel thermal desalination system which can work using solar energy.

The most common methods for desalination are membrane-based reverse osmosis and thermal desalination. However, both consume a lot of energy.

Thermal desalination systems work by heating saltwater and then condensing the resulting vapor to obtain freshwater. But the energy required for evaporation is usually obtained from either electricity or combustion of fossil fuels. An environmentally friendly alternative is using solar stills in which solar energy is employed to evaporate saltwater in large reservoirs and the vapor that condenses on a transparent roof is collected. However, during condensation, a thin layer of water forms on the roof, reducing the amount of solar energy that can penetrate the reservoir and therefore the system’s efficiency.

As an alternative to such solar stills, the IISc team has developed a novel design for a solar-powered desalination unit that is more energy-efficient, cost-effective and portable, making it convenient to set up in areas with limited access to continuous electricity, explains Susmita Dash, Assistant Professor in the Department of Mechanical Engineering and corresponding author of the study published in Desalination.

The setup, designed by Dash and Ph.D. student Nabajit Deka, comprises a reservoir of saline water, an evaporator, and a condenser enclosed within an insulating chamber to avoid heat losses to the ambient air.

Their system works by using solar thermal energy to evaporate a small volume of water imbibed or “wicked” into the evaporator, which has a textured surface. The wicking of liquid into the evaporator takes advantage of the capillary effect of microscale textures. This effect allows liquids to be drawn into narrow spaces of a porous material, much like water being absorbed by a sponge. Utilizing this approach, instead of heating the entire liquid volume in the reservoir, results in a significant improvement in the system’s energy efficiency, says Dash.

The team etched tiny grooves on the surface of the evaporator, which is made of aluminum. Deka explains that they had to experiment with different combinations of groove dimension and spacing as well as surface roughness to determine the right pattern for efficient wicking.

The condenser—often overlooked in a majority of desalination studies, according to the researchers—is another key element of the solar desalination system. To prevent the formation of the water film during condensation, like in the solar stills, Dash and Deka fabricated a condenser with alternating hydrophilic and superhydrophilic surfaces. The water droplets condensing on the hydrophilic patterns are pulled towards the superhydrophilic region. This affinity of the condensed water to the superhydrophilic region enables the hydrophilic surface to become free for a fresh batch of condensate, explains Dash.

During condensation, some heat gets lost to the atmosphere. The researchers designed the system in such a way that this heat released during condensation is also trapped and utilized to heat up the imbibed saltwater in a different evaporator at the backside of the condenser, which reduces the amount of solar energy needed, and increases the efficiency of the system even more.

The team also successfully connected multiple evaporator-condenser combinations in a series, resulting in a multi-stage solar desalination system. This system, if built in a footprint area of 1 m², has the capacity to produce one liter of potable water every 30 minutes—at least twice as much as that produced by a traditional solar still of the same size.

Apart from seawater, the system can also work with groundwater containing dissolved salts as well as brackish water. It can be adjusted to align with the shifting positions of the sun during the day.

The researchers are currently working on scaling up the system and improving its durability, and increasing the volume of drinking water produced, so that it can be deployed for domestic and commercial use.

German truck maker Daimler, Japan’s top automaker Toyota and two other automakers said Tuesday they will work together on new technologies, including using hydrogen fuel, to help fight climate change.

The companies said Mitsubishi Fuso Truck and Bus Corp., whose top stakeholder is Daimler Truck, and Hino Motors, the truck maker in the Toyota group, will merge. Daimler Truck and Toyota Motor Corp. will equally invest in the holding company of the Mitsubishi-Hino merger, they said without giving a dollar amount for the deal.

The companies plan to cooperate in reducing carbon emissions and developing other technologies such as autonomous driving, net-connected services and electric vehicles.

“This collaboration among our four companies is a partnership for creating the future of commercial vehicles in Japan and the future of a ‘mobility society,’ said Toyota Motor Corp. Chief Executive Koji Sato.

The two truck companies will work on commercial vehicle development, procurement and production to become globally competitive, the executives said.

“We at Daimler Truck are very proud of our products, because trucks and buses keep the world moving. And soon they will even do so with zero emissions,” said Daimler Truck Chief Executive Martin Daum.

“Today’s announcement is a crucial step in making that future work economically and in leading sustainable transportation.”

Automakers are rushing to keep up with the global shift toward less polluting vehicles and to help in other ways to combat climate change. Commercial vehicles like trucks and buses are major contributors to auto emissions. In some cases rivals are joining forces to gain a a competitive edge and cut costs through “economies of scale” of by sharing knowledge and resources.

“It is hard to go at it alone. Working together is crucial,” Sato said,

Fuel cells power Toyota’s buses in Japan but its strength has been in hybrids, which have both electric motors like EVs and gasoline engines. Consumer acceptance of battery powered EVs has come faster than expected, Toyota officials say, and the company is hard at work on rolling out EVs in various markets.

Details of the merger, including shareholding ratios, the company name and its structure will be worked out over the next 18 months, the companies said. They aim to sign a definitive agreement by early next year and close the transaction by the end of 2024. The deal still needs shareholders’ and regulatory approval.

The deal is a chance for a fresh start at Hino, its chief executive, Satoshi Ogiso said, after the company‘s image was marred by its disclosure last year that it had systematically falsified emissions data beginning as early as 2003.

“We will unite our aspirations to ‘support mobility and contribute to society’ and hand in hand accelerate advanced technology development to overcome the increasingly fierce global competition,” he said.

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