Achieving optimal efficiencies for nanoengines

first_img(PhysOrg.com) — “There’s a lot of recent interest in understanding the functioning and optimal performance of small systems,” Katja Lindenberg tells PhysOrg.com. Lindenberg is a scientist in the Department of Chemistry and Biochemistry and the Institute for Nonlinear Science at the University of California, San Diego, in La Jolla. Along with Massimiliano Esposito, also at the Institute, and Christian Van den Broeck at Hasselt University in Diepenbeek, Belgium, Lindenberg has been studying the efficiency of very small thermochemical engines. “Thermodynamics applied to small systems is different from what we are used to,” Lindenberg continues. “It’s a relatively new field, and we are trying to understand optimal performance criteria.” The results of an investigation by Lindenberg, Esposito and Van den Broeck into power generation by small thermochemical engines is presented in Physical Review Letters: “Universality of Efficiency at Maximum Power.”Lindenberg explains that “maximum efficiency is achieved only near equilibrium, where the power output is very small. Instead of focusing on maximum efficiency alone, we are studying how to achieve maximum possible efficiency at maximum power.”Esposito says that in order to explore the general rules that govern performance at maximum power, a general single framework is needed – one that can encompass many systems that on the surface appear very different from one another. “The systems of interest all produce a workflow, or power, fueled by a heat flow through the system generated by a temperature gradient,” he says. “Optimal efficiency at maximum power is obtained when the heat and work fluxes are strongly coupled. For instance, if the workflow is a flow of particles against a chemical potential gradient, strong coupling occurs when the only carriers of heat are the same particles.” “This strong coupling between the work and heat flows is a natural feature of small systems — nanosystems,” Esposito continues, “but would be difficult or impossible to achieve in a macroscopic system.” The team has illustrated this concept in a paper appearing in Europhysics Letters, in which they consider electrons flowing through a quantum dot.Both Lindenberg and Esposito emphasize that, so far, their work is purely theoretical and only illustrated in model systems. “It might be difficult to build a device that satisfies the conditions we have set out,” Lindenberg admits, “but on a fundamental level it gives a conceptual basis for what is possible. It provides an idea of what the ultimate goal would be when it comes time to design a device.”What sort of devices might be possible? Like many theorists, Esposito and Lindenberg hesitate to prognosticate. However, Esposito mentions at least one idea regarding the use of thermochemical engines: “Perhaps a device could be created to recover the energy from heat loss in a car’s engine.”For now, though, work moves forward in trying to understand small systems and their properties. “With continued interest in the smallest of systems,” Esposito points out, “it is increasingly important to learn how one can use extremely small systems to achieve optimal efficiencies at maximum power.”More information: Esposito, Lindenberg and Van den Broeck, “Universality of Efficiency at Maximum Power.” Physical Review Letters (2009). Available online: link.aps.org/doi/10.1103/PhysRevLett.102.130602 . Esposito, Lindenberg and Van den Broeck, “Thermoelectric efficiency at maximum power in a quantum dot.” Europhysics Letters (2009). Available online: www.iop.org/EJ/abstract/0295-5075/85/6/60010/ . Copyright 2009 PhysOrg.com. All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com. Explore further Discovery Captures, Converts Heatcenter_img This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Citation: Achieving optimal efficiencies for nanoengines (2009, April 29) retrieved 18 August 2019 from https://phys.org/news/2009-04-optimal-efficiencies-nanoengines.htmllast_img read more

National security expert warns of Asian space race

National security expert warns of Asian space race

first_img More information: Technology: Asia’s space race, Nature 480, 171–173 (08 December 2011) doi:10.1038/480171a Journal information: Nature China Xichang Satellite Center; The launch of Tianlian I-01 satellite (a Data Relay & Tracking Satellite); The newly developed Long March 3C Carrier Rocket. Image: Wikipedia. Explore further Moltz writes that despite denials by the major Asian players, there exists the beginnings of a space race among the most technologically advanced countries in the area. In the lead of course is China, which besides the United States and Russia, is the only country to have put a person in space on its own. Other Asian countries actively involved in space technology include India, South Korea and Japan, though others such as Vietnam, Indonesia, Malaysia, Thailand and Taiwan are working on building a presence as well.Japan of course, has been actively involved with the International Space station, and India has been putting nerves on edge by mixing its space technology with military goals by building rockets capable of carrying a payload all the way to Beijing. The country has also launched its own rockets into space to deliver satellites, though it’s not yet achieved the broad range of successes of the Chinese program.The problem with an Asian space race, Moltz contends, is that it builds an arena of unhealthy competition bred out of historic geopolitical rivalries. It also wastes resources, but that’s not something that should concern other countries. What should he writes, is the possibility of an Asian space race morphing into an Asian arms race, something that could impact virtually every nation on Earth.The current situation, he explains, is a collection of Asian countries who are unwilling to work together to meet mutual goals such as can be seen with the European Space Agency (ESA). Instead, individual countries work independently, quite often duplicating work done by other countries both in Asia and in the west, resulting in secretive programs that have as a goal beating one another to the next level, rather than building programs that serve the national, or international good.What is perhaps most chilling about an Asian space race is the way China, which is the clear leader, has gone about its space program, highlighted not by its triumphs in manned exploration, but in it’s destruction of one of its dead weather satellites by an anti-satellite weapon back in 2007. Not only did that action contribute to the vast collection of space junk, but it sent shock waves through the entire international community as it demonstrated very clearly the types of technology China has been secretly working on. And because of its leadership role in the Asian community, the action has likely set other countries to develop their own such weapons.One other worrisome offshoot of the space race is the impact it might have on those Asian countries unable to join in. Pakistan, for example, a country with nuclear weapons, has voiced concerns over the missile technology that India has developed and has repeatedly made it clear that any actions by India it deems a threat to its own survival would be met with all out war, including the use of nuclear bombs. (PhysOrg.com) — James Clay Moltz, an associate professor in the department of national security affairs at the Naval Postgraduate School in Monterey, California, has published a commentary paper in the journal Nature where he warns of a possible space race involving many Asian nations, possibly leading to an arms race.center_img This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Citation: National security expert warns of Asian space race (2011, December 8) retrieved 18 August 2019 from https://phys.org/news/2011-12-national-expert-asian-space.html Bangladesh, Pakistan Team Up With China On Space Cooperation © 2011 PhysOrg.comlast_img read more

A more indepth way to predict gunshot wound blood spatter

A more indepth way to predict gunshot wound blood spatter

first_img Researchers shoot pigs in the head in blood-spatter study This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. © 2016 Phys.org Citation: A more in-depth way to predict gunshot wound blood spatter (2016, August 3) retrieved 18 August 2019 from https://phys.org/news/2016-08-in-depth-gunshot-wound-blood-spatter.html (Phys.org)—A small team of researchers from the University of Illinois and Iowa State University has developed what they describe as a theoretical model for both interpreting and predicting blood-spatter that results from a gunshot wound. In their paper published in the journal Physical Review Fluids, the group describes the factors they took into consideration in developing their model and how well it worked in experiments conducted with pig blood and sponges. Explore further More information: P. M. Comiskey et al. Prediction of blood back spatter from a gunshot in bloodstain pattern analysis, Physical Review Fluids (2016). DOI: 10.1103/PhysRevFluids.1.043201ABSTRACTA theoretical model for predicting and interpreting blood-spatter patterns resulting from a gunshot wound is proposed. The physical process generating a backward spatter of blood is linked to the Rayleigh-Taylor instability of blood accelerated toward the surrounding air, allowing the determination of the initial distribution of drop sizes and velocities. Then the motion of many drops in air is considered with governing equations accounting for gravity and air drag. Based on these equations, a numerical solution is obtained. It predicts the atomization process, the trajectories of the back-spatter drops of blood from the wound to the ground, the impact angle, and the impact Weber number on the ground, as well as the distribution and location of bloodstains and their shape and sizes. A parametric study is undertaken to predict patterns of backward blood spatter under realistic conditions corresponding to the experiments conducted in the present work. The results of the model are compared to the experimental data on back spatter generated by a gunshot impacting a blood-impregnated sponge. When a person is shot dead and there are no witnesses, forensic investigators attempt to use every bit of evidence they can find at a crime scene to figure out what happened; one source is blood spatter that occurs when a victim’s blood is sent flying against walls or onto the floor as a bullet enters the body and then again as it exits. In this new effort, the researchers have developed a model to help better describe spattering events which could lead to a more accurate depiction of a crime scene.Up till now, forensic experts have used three basic types of spatter results to assist in identifying the type of bullet wound that caused it: high, medium and low velocity. Using such categories helps to identify the type of weapon used to propel the bullet. But this approach, the researchers claim, fails to take into account other factors such as gravity and air resistance which can cause blood to follow an arc as it falls. To correct that problem, the researchers built theoretical models meant to describe what happens when a dense liquid such as blood runs directly into a gas such as air. They also factored in the mass of the bullet, its speed and its angle as it strikes the body. The result was a mode that describes a resulting “blood cloud” for a given set of circumstances.To test their model, the researchers soaked sponges in pig blood and shot them, taking measurements of the blood spatters that resulted. They report that their results were mixed, though they were within an order of magnitude of predictions. They plan to run more experiments using different types of guns and bullets to make their model progressively better. They believe that at some point the model will be good enough for use with real crime scenes. (a) Reconstruction of the trajectories associated with four bloodstains using straight trajectories versus ballistic trajectories and the geometry (locations of the stains, of the victim, and the impact angles). Panel (a) is reproduced from teaching material graciously provided by H. McDonell. Drop size is assumed to be 3 mm, implying velocities in the 5.3–7.5 m/s range. (b) Definition of the angle of drop impact α and directional (sideways) angle γ, which is equal to the angle between the vertical plane containing the drop trajectory and another vertical plane containing the bullet trajectory and the target. Credit: (c) Physical Review Fluids (2016). DOI: 10.1103/PhysRevFluids.1.043201last_img read more

Matters of the Heart

Matters of the Heart

first_imgDirect Dil Se, an annual music festival was organised on Sunday to celebrate the occasion of the World Heart Day. The festival supported by the Directorate of Health, Delhi Government and Billion Hearts Beating Foundation was arranged to spread awareness about heart health through a music venture.The concept of Direct Dil Se (DDS) seeks to draw attention to the growing concern about cardiac health in the country, where approximately 10% of the country’s 1.2 Billion plus population is affected by coronary heart diseases. Also Read – ‘Playing Jojo was emotionally exhausting’The concert featured the Wadali brothers and other famous musicians. Some of them included Bobby Cash, Shibani Kashyap, Mame Khan, Suhail Yusuf Khan and Ashish Chuahan. The event also included a talk by Dr. KK Talwar, chairman, board of governors, Medical Council of India. Dr. Talwar addressed various heart-related factors and pointers on maintaining a healthy life and a healthy heart. He commented on the relevance on the concert and said, ‘ Music has therapeutic effects on humans, it lowers anxiety which helps people prevent stress-related lifestyle diseases. Music also helps one recover better and from ailments. So the theme of this concert is quite valid.’Organizer of DDS, Ashok Nagpal said, ‘Direct Dil Se is the first of its kind initiative that attempts to connect to youth through the language of music. Awareness of heart health starts at an early age; hence we aim to reach them young.’last_img read more

Dreams dont catch fire

Dreams dont catch fire

first_imgRemember your graduation days, all the fun, escaping the punishments, bunking with friends and late night dorm studies? Yes Dada by Vibhor Tikiya will take you back to your golden era.Dada, is the guy your parents warned you about when you were joining college. He is the quintessential ‘bad influence.’ And this is the story of a young boy from Kolkata who did fairly well  in his studies, was loved by his father, adored by his mother and also has a sharp brain. Also Read – ‘Playing Jojo was emotionally exhausting’Life takes a turn when his father dies unexpectedly in an accident.From there on, he barely manages his studies and in an attempt to support his mother, he masters the art of manipulation. He scores 45 per cent in his 12th standard examinations. But his mother dreams of seeing him studying in one of the premier engineering institutes of the country.Being the manipulator that he is, Dada forges a few certificates to get admission in one of the best colleges of the land. Surprisingly, he gets in and from there on, his life revolves not around studying, but making money, selling alcohol in the campus, bartending, copying and so on. He forms a gang of four, Vivek – the geek, Divya – the beauty with brains, Jhon – the good for nothing and Dada himself. The story revolves around these four friends and their (mis)adventures through the glorious years in college. Also Read – Leslie doing new comedy special with NetflixAll four of them look upto Dada in times of trouble. It is evident that Dada’s adventures tend to succeed most of the times as he has nothing to lose. He has incredible negotiation skills, he cares about his friends and though he is reluctant to change and try new things, but he does chart fresh waters after a bit of motivation from his friends.It is how they handle several tricky situations, pull strings and finally manage to get an engineering degree forms the core of the story. By the end of the college years, after fulfilling his mother’s dreams of getting a respectable degree, Dada realises that he doesn’t have a dream of his own so he sets out to fulfil his father’s wish of becoming a teacher.The second half of the book is set in US where Dada has joined an engineering firm to complete his PhD. After failing the first few exams he changes his department and moves to fine arts. Story unfolds from there on…The book talks about how a person grows up by making mistakes, laughing and crying with friends, trying to fulfil responsibilities. But at the core its message is clear ‘Properties catch fire, Dreams don’t.’ However, it does leave you with some questions.How do you handle challenges presented by life and people around you, as it determines how successful you will be. Can you confront a challenge, or do you plan to run away from it? Do you succumb to your fate and adjust to it? Learn to deal with challenges well and you’ll enjoy the same.last_img read more

Modimania and the Muslim turnaround

Modimania and the Muslim turnaround

first_imgFilmmaker and social activist Mahesh Bhatt, who once campaigned for the Congress during elections, has taken a positive attitude towards Narendra Modi. ‘We as civil society must acknowledge, applaud and reciprocate the gesture of Gujarat chief minister,’ Bhatt told Sudesh Verma, author of the new book Narendra Modi: The Gamechanger. Mahesh Bhatt’s statement came after Modi’s expression of remorse in his blog following his exoneration by the Ahmedabad Court in the case involving Zakia Jafri. Also Read – ‘Playing Jojo was emotionally exhausting’The aggrieved side should now take the initiative to set aside the acrimony and create conditions to enable people to live in peace and harmony, he said. ‘I personally feel, whenever anybody — no matter how opposed I may be to his politics — makes a gesture of reconciliation, talks about harmony and talks about healing the wounds; it must be applauded, acknowledged and reciprocated. This is my response. If I keep talking about peace and I do not take the initiative to bring peace, then I do not want peace. And I do not live of conflict, there are people who live of conflict.’ Also Read – Leslie doing new comedy special with NetflixThis is the biggest indictment of that section of public opinion makers that thrives on conflict and hate. Bhatt’s gesture of reconciliation is being echoed by many prominent Muslims who have begun to look at Modi with hope. The book, in fact, argues that there is likely to be a Muslim turnaround for Modi in the country.The biggest example is the statement by Mufti Aijaz Arshad Qasmi, the youngest member of the All India Muslim Personal Law Board, who says Modi will be a good Prime Minister who will deliver justice to all.He said that worse riots had taken place in the country. It was Modi’s bad luck that he was the chief minister of Gujarat in 2002, the book has quoted the Mufti as saying.last_img read more

Time for some golf

first_imgEros Hotel organised a putting tournament at the Golf Putting Green area held under the guidance of International Golfer and Coach Amandeep Johl. Guests at the hotel enjoyed the game as they were able to hone their golf putting skills as well as challenge fellow likeminded golfers at the event. The tournament was followed by prize giving ceremony and breakfast at the Private Dining Room of Empress of China, the hotel’s Chinese specialty restaurant.last_img

Forms of life

Forms of life

first_imgResonance, meaning reverberation or echo actually talks about things that are present continuous. Menon’s bronzes exemplify not just dancers or acrobats, but movement and dynamism at its best. There is a unity which integrates dance, dramatic action and artistic rendition. Her works easily become a part of any landscape or sometimes crafts a theatrical drama in the space it is kept. Her works are allegorically replicating the theme like a long, philosophical poem. Through simplicity and true life staging, these bronzes will combine the most contemporary techniques with deep perception into psychological imagery. Also Read – ‘Playing Jojo was emotionally exhausting’Dimpy Menon, born 1963 at Ahmedabad is a graduate in fine arts from the College of Art Chennai in first class and learnt sculpting at the Central St. Martin’s in London. She has continued to work as a sculptor throughout her career refining her form and technique with consistent practice. Metal, that she likes to work in, seems to turn into lithe material as she moulds it to give form to her kinetic compositions that celebrate life. The stones that she searches and collects to chisel and refine before adding to her metal sculpture add a distinct look to her work. Also Read – Leslie doing new comedy special with NetflixHer installations depict flexibility and agility of human form in various dynamics and movements. Handling the entire laborious process of sculpting from a drawing to clay to bronze, working on her own, Menon creates installations, some that are small and can be hand held or displayed on table top and others in larger than life scale for outdoor and open spaces. Many of her work adorns public spaces in Chennai. She has participated in some important workshops and is two times winner of Venkatappa Art Gallery and Museum Scholarship and State Lalit Kala award. She had a solo booth at the India Art Fair, 2014 with Gallery Art Positive. The artist is currently working on some large commissions besides preparing for a solo. She lives and works in Bangalore.WHERE: Gallery Art Positive WHEN: On till 31 Octoberlast_img read more

TransAsia starts pilot retraining after deadly crash cancels dozens of flights

TransAsia starts pilot retraining after deadly crash cancels dozens of flights

first_imgTransAsia Airways cancelled dozens of flights on Saturday, the first day of a pilot retraining programme, as rescuers retrieved five more bodies from the river in Taiwan where the plane crashed.Taiwan’s Civil Aeronautics Administration (CAA) ordered all the airline’s staff who fly ATR planes to take tests on operating the aircraft after it emerged the pilots may have inexplicably shut off one of the engines before Flight GE235 went down last week. “Starting today, all of TransAsia’s 71 ATR pilots will undergo tests to be carried out by the CAA and third-party professional units for an estimated period of four days,” the carrier said in a statement. Also Read – Pro-Govt supporters rally as Hong Kong’s divisions deepen“As a result, some of our domestic flights will be adjusted,” it said, explaining that 90 domestic flights will be cancelled by Monday.Pilots who fail the tests will be grounded immediately for an indefinite period of time pending further qualification training, according to the CAA.On Wednesday, a TransAsia ATR 72-600 plane plunged into a river in Taipei with 53 passengers and five crew members on board. Forty people were killed, fifteen survived and rescuers are still searching for another three who remain missing in the airline’s second deadly crash in seven months.Five bodies were found downstream of the crash site, including one in flight attendant’s uniform, during a blanket search of the river by hundreds of rescuers and divers today, Taipei city fire department said.last_img read more

You always do this Sonia pulls up Tharoor

You always do this Sonia pulls up Tharoor

first_imgKnown for his outspoken nature, Congress leader Shashi Tharoor was on Wednesday reprimanded by party president Sonia Gandhi, after his comments at a party meeting went public. Tharoor had reportedly said on Tuesday that he was not in favour of disrupting Parliament over the party’s demand for the resignation of three top BJP leaders.“You always do this, it’s become a habit with you,” sources quoted Gandhi angrily telling Tharoor at the meeting with MPs. Stunned Congressmen looked on, before Congress vice-president Rahul Gandhi ushered them out with comments to intended to lighten the moment. Also Read – Need to understand why law graduate’s natural choice is not legal profession: CJISonia Gandhi’s rare and unexpected outburst reportedly came after other lawmakers complained against Tharoor that he had breached the party discipline. His alleged comments were carried in newspapers. Earlier in the day, Gandhi openly told media that “let them say what they want, we will continue to protest”.The Congress, which has 44 MPs in the Lok Sabha, has adopted an aggressive stance in Parliament, giving notice to the government that it will not allow the Houses to function till External Affairs Minister Sushma Swaraj, Rajasthan Chief Minister Vasundhara Raje and Madhya Pradesh Chief Minister Shivraj Singh Chouhan are sacked.Gandhi has directed her MPs to voice a strong and firm opposition against the issues. They all wore black bands on their arms as they were entered Parliament on Wednesday. The first two days of the Monsoon session have been washed out by the Congress protests.last_img read more