这是在nature上发表的一篇报道，很好的说明了量子计算目前发展的状况。 Quantum computers ready to leap out of the lab in 2017 Google, Microsoft and a host of labs and start-ps are racing to turn scientific curiosities into working machines. Davide Castelvecchi 03 January 2017 Article tools Quantum computing has long seemed like one of those technologies that are 20 years away, and always will be. But 2017 could be the year that the field sheds its research-only image. Computing giants Google and Microsoft recently hired a host of leading lights, and have set challenging goals for this year. Their ambition reflects a broader transition taking place at start ups and academic research labs alike: to move from pure science towards engineering. “People are really building things,” says Christopher Monroe, a physicist at the University of Maryland in College Park who co-founded the start-up IonQ in 2015. “I’ve never seen anything like that. It’s no longer just research.” Google moves closer to a universal quantum computer Google started working on a form of quantum computing that harnesses superconductivity in 2014. It hopes this year, or shortly after, to perform a computation that is beyond even the most powerful ‘classical’ supercomputers — an elusive milestone known as quantum supremacy. Its rival, Microsoft, is betting on an intriguing but unproven concept, topological quantum computing , and hopes to perform a first demonstration of the technology. The quantum computing start up scene is also heating up. Monroe plans to begin hiring in earnest this year. Physicist Robert Schoelkopf at Yale University in New Haven, Connecticut, who cofounded the start up Quantum Circuits, and former IBM applied physicist Chad Rigetti, who set up Rigetti in Berkeley, California, say they expect to reach crucial technical milestones soon. Academic labs are at a similar point. “We have demonstrated all the components and all the functions we need,” says Schoelkopf, who continues to run a group racing to build a quantum computer at Yale. Although plenty of physics experiments still need to be done to get components to work together, the main challenges are now in engineering, he and other researchers say. The quantum computer with the most qubits so far — 20 — is being tested in an academic lab led by Rainer Blatt at the University of Innsbruck in Austria. Inside Microsoft’s quest for a topological quantum computer Whereas classical computers encode information as bits that can be in one of two states, 0 or 1, the ‘qubits’ that comprise quantum computers can be in ‘superpositions’ of both at once. This, together with qubits’ ability to share a quantum state called entanglement, should enable the computers to essentially perform many calculations at once. And the number of such calculations should, in principle, double for each additional qubit, leading to an exponential speed-up. This rapidity should allow quantum computers to perform certain tasks, such as searching large databases or factoring large numbers, which would be unfeasible for slower, classical computers. The machines could also be transformational as a research tool, performing quantum simulations that would enable chemists to understand reactions in unprecedented detail, or physicists to design materials that superconduct at room temperature. “I tell my students that 2017 is the year of braiding.” There are many competing proposals for how to build qubits. But there are two front runners, confirmed in their ability to store information for increasingly long times — despite the vulnerability of quantum states to external disturbance — and to perform quantum-logic operations. One approach, which Schoelkopf helped to pioneer and which Google, IBM, Rigetti and Quantum Circuits have adopted, involves encoding quantum states as oscillating currents in superconducting loops. The other, pursued by IonQ and several major academic labs, is to encode qubits in single ions held by electric and magnetic fields in vacuum traps. John Martinis, who worked at the University of California, Santa Barbara, until Google hired him and his research group in 2014, says that the maturity of superconducting tech- nologyprompted his team to set the bold goal of quantum supremacy. The team plans to achieve this using a ‘chaotic’ quantum algorithm that produces what looks like a random output ( S. Boixo et al. Preprint at https://arxiv.org/abs/1608.00263; 2016 ). If the algorithm is run on a quantum computer made of relatively few qubits, a classical machine can predict its output. But once the quantum machine gets close to about 50 qubits, even the largest classical supercomputers will fail to keep pace, the team predicts. Quantum computer makes first high-energy physics simulation The results of the calculation will not have any uses, but they will demonstrate that there are tasks at which quantum computers are unbeatable — an important psychological threshold that will attract the attention of potential customers, Martinis says. “We think it will be a seminal experiment.” But Schoelkopf does not see quantum supremacy as “a very interesting or useful goal”, in part because it dodges the challenge of error correction: the ability of the system to recover its information following slight disturbances to the qubits, which becomes more difficult as the number of qubits increases. Instead, Quantum Circuits is focused on making fully error-corrected machines from the start. This requires building in more qubits, but the machines could also run more-sophisticated quantum algorithms. Monroe hopes to reach quantum supremacy soon, but that is not IonQ’s main goal. The start-up aims to build machines that have 32 or even 64 qubits, and the ion-trap technology will enable their designs to be more flexible and scalable than superconducting circuits, he says. Microsoft, meanwhile, is betting on the technology that has the most to prove. Topological quantum computing depends on excitations of matter that encode infor-mation by tangling around each other like braids. Information stored in these qubits would be much more resistant to outside disturbance than are other technologies and would, in particular, make error correction easier. Sign up - it's free! No one has yet managed to create the state of matter needed for such excitations, let alone a topological qubit. But Microsoft has hired four leaders in the field, including Leo Kouwenhoven of the University of Delft in the Netherlands, who has created what seems to be the right type of excitation. “I tell my students that 2017 is the year of braiding,” says Kouwenhoven, who will now build a Microsoft lab on the Delft campus. Other researchers are more cautious. “I am not making any press releases about the future,” says Blatt. David Wineland, a physicist at the National Institute of Standards and Technology in Boulder, Colorado, who leads a lab working on ion traps, is also unwilling to make specific predictions. “I’m optimistic in the long term,” he says, “but what ‘long term’ means, I don’t know.” Nature 541, 9–10 (05 January 2017)
Computerworld - When one talks of computers today, he or she could be referring to a laptop, a desktop or maybe even a smartphone. Sergey Brin, CEO and co-founder of Google, wears Google Glasses during a product demonstration at the Google I/O 2012 conference last month. (Image: Stephen Lam / Reuters) However, if Google's latest plan stays on track, the definition of a computer could broaden significantly. At its Google I/O developers conference in San Francisco, the company threw a lot of effort behind the unveiling of a prototype of its so-called Google Glass computerized eyeglasses. The Android-powered eyeglasses are equipped with a processor, memory, camera, GPS sensors and a display screen. Google co-founder and CEO Sergey Brin said the Google Glass development effort is all about "doing brand new risky technological things that are really about making science fiction real." In that world of science fiction, he said, computers won't always look like what we now expect from the term. The next generation of computers won't necessarily sit on one's desk or lap or in one's hand. The devices may not have a have a monitor and/or keyboard. Someday - probably in the near future - computers will be worn, whether incorporated into glasses, or in a piece of jewelry such as a bracelet or something else, analysts say. "Google Glass changes the way we will look at computers," said Patrick Moorhead, an analyst at Moor Insights Strategy. "It isn't just research, it's a workable prototype." "Glass serves to stretch the technology ecosystem to even greater lengths, Moorhead said. "I believe that in five years we will see many different form factors and brands of wearable computers. We will have computers embedded in our glasses of course, but also in our jewelry and watches." Moorhead noted that the U.S. military, especially the Special Forces units, already use wearable computers to for communications and GPS tasks. That technology hasn't yet reached consumer or business users, he added. Google's research efforts could hasten the mainstream use of the technologies. "As we see real devices in use that we previously saw only in movies and books, it will expand the possibilities even further," said Moorhead. "We can go beyond the glasses and visualize computers in our jewelry, in our watches and even inside our bodies." Charles King, an analyst at Pund-IT, said such new computing form factors are an extension of the current mobile trend, taking GPS-enabled smartphones, growing compute power and multiple new communications capabilities to the next level. "It's the ever smaller and ever more powerful mobile technologies," he added. "It's about the things we used to see and think about in relation to sci-fi novels or Star Trek . The idea of highly mobile and highly powerful computers is extremely intriguing." King said he expects there will be great demand for what he calls "mobile computing lifestyle choices" in a few years. "It would not surprise me if we see a lot of this in, say, five years," he noted. "As the technology becomes more sophisticated and cheaper, it becomes something everybody can afford." "Some years ago, a smartphone like the Blackberry was considered something that only business professionals needed. It doesn't seem farfetched to think we could see Google Glass widely adopted in five years," King added. Rob Enderle, an analyst with the Enderle Group, pointed out that Google Glass or other wearable computers could be very useful in many workplaces -- not just the next big thing to help users look cool or geeky. "They could be used regularly for things like taking inventory in warehouses, and for tasks on factory floors and other places where folks need to use computers and their hands at the same time," Enderle said. At the Google I/O conference, the company said it is offering prototype versions of Google Glass, dubbed the Google Glass Explorer Edition, to developers for $1,500. Brin said he expects the glasses to be generally available in 2014 -- at a lower price. "If the developer community can come up with interesting solutions, the sky's the limit," said King. Enderle said that wearable computers could be a big step toward a new generation of compute form factors that can be embedded inside the human body. Putting aside visions of Star Trek's Borg initiative, Moorhead and Enderle agreed that wearable computers are a bridge to the first such computer implants. "It's an interim step toward imbedding computers into people and creating some kind of biomechanical interface that bypasses the eyes," Enderle said, adding that he believes that computer generation is some 25 to 50 years away. "The change we are working toward ... is one of the big changes we will see in computing this century. It will redefine personal computing by the time it has fully matured," he added. From: http://www.computerworld.com/s/article/9228776/Google_Glass_launches_new_age_of_personal_computing?taxonomyId=12pageNumber=2 Google Glass，这儿的Glass译成“眼镜”是受文中所附图片的影响，不知是否合适？ 将来不远的一天，“个人计算”将不再只是利用笔记本电脑、智能手机等传统的终端，我们对它的认知也会发生很大的改变。未来的“个人计算”是什么样子？
China's Supercomputing Prowess As with gross domestic product, China is now solidly No. 2 By Samuel K. Moore/April 2011 Click on the image for a larger view. Did you feel that? That was the supercomputing world lurching eastward. In the last accounting of the world's 500 fastest machines , China surprised everyone by taking the top spot. It's gone from having 3 in the top 500 at the beginning of the decade to 41, besting historic processing princes Germany and Japan. China is still far behind the consistent computational king, the United States, which has historically commanded about half the list. But world-class supercomputing prowess—or at least the bragging rights to it conferred by the Top 500 list—is more a question of quality than of quantity. Add up the processing potential of all 500 top supercomputers and you get an almost unfathomable 43 673 000 billion floating-point operations per second (43 673 teraflops). But it's the cream of the crop that make all the difference. By themselves, the top 10 computers provide 28 percent of the list's teraflops, and you need only the top 45 machines to account for half. China's big break came not by doubling its presence on the list but by building one really powerful computer at its apex. The Tianhe-1A system at the National Supercomputer Center, in Tianjin , boasts a performance of 2570 teraflops—about 6 percent of the list's total. Another reckoning of the supercomputer universe is due in June. Watch for new high-ranking entrants from Japan, the United States—and China. http://spectrum.ieee.org/at-work/innovation/chinas-supercomputing-prowess
Computers and Electronics in Agriculture Volume 71, Issue 1, (April 2010) 1. Editorial Board 2. Editorial Board 3. Calculation of soil electrical conductivity using a genetic algorithm 4. Assessing the ventilation performance of a naturally ventilated livestock building with different eave opening conditions 5. A Bayesian network to predict the probability of organic farms exit from the sector: A case study from Marche, Italy 6. RTK GPS mapping of transplanted row crops 7. An on-site computer system for comprehensive agricultural air quality research 8. Simplify the interpretation of alert lists for clinical mastitis in automatic milking systems 9. Modelling uncertainty in field grown iceberg lettuce production for decision support 10. On the use of plate-type normal pressure cells in silos: Part 2: Validation for pressure measurements 11. On the use of plate-type normal pressure cells in silos: Part 1: Calibration and evaluation 12. Development of an automated climatic data scraping, filtering and display system 13. Development of expert system modeling based decision support system for swine manure management 14. Optimization of sourcesink dynamics in plant growth for ideotype breeding: A case study on maize Corrigendum 15. Corrigendum to Assessment of nitrogen losses to the environment with a Nitrogen Trading Tool (NTT) 更多农业工程核心文献题录信息，请登录农业工程学科知识库查询： http://aekd.cau.edu.cn
Computers and Electronics in Agriculture Volume 70, Issue 2, (March 2010) Special issue on Information and Communication Technologies in Bio and Earth Sciences 1. Editorial Board 2. Editorial Board 3. Editorial 4. Plant virus identification based on neural networks with evolutionary preprocessing 5. An intelligent system employing an enhanced fuzzy c-means clustering model: Application in the case of forest fires 6. Forest management planning expert system for wildfire damage reduction 7. Web and mobile technologies in a prototype DSS for major field crops 8. Metadata interoperability in agricultural learning repositories: An analysis 9. The role of trust in the transition from traditional to electronic B2B relationships in agri-food chains 10. Software architecture for farm management information systems in precision agriculture 11. Agricultural e-government services: An implementation framework and case study 12. Web services for rural areasSecurity challenges in development and use 13. Location-aware system for olive fruit fly spray control 14. Factors affecting the Internet behaviour of horticultural growers in Flanders, Belgium 15. A complete farm management system based on animal identification using RFID technology 16. Organizing information integration in agri-foodA method based on a service-oriented architecture and living lab approach 更多农业工程核心文献题录信息，请登录农业工程学科知识库查询： http://aekd.cau.edu.cn
Computers and Electronics in Agriculture Volume 70, Issue 1, (January 2010) 1. Editorial Board 2. Editorial Board Review 3. Evaluation of sensing technologies for on-the-go detection of macro-nutrients in cultivated soils 4. Potential for pesticide and nutrient savings via map-based automatic boom section control of spray nozzles 5. Color grading of beef fat by using computer vision and support vector machine 6. Gaussian processes based bivariate control parameters optimization of variable-rate granular fertilizer applicator 7. An automatic machine vision-guided grasping system for Phalaenopsis tissue culture plantlets 8. Assessing nutritional status of Festuca arundinacea by monitoring photosynthetic pigments from hyperspectral data 9. Decision-tree induction to detect clinical mastitis with automatic milking 10. A PDA-based record-keeping and decision-support system for traceability in cucumber production 11. From pixel to vine parcel: A complete methodology for vineyard delineation and characterization using remote-sensing data 12. Challenges in the design of a GNSS ear tag for feedlot cattle 13. Automatic fruit and vegetable classification from images 14. Dynamic modeling and simulation of greenhouse environments under several scenarios: A web-based application 15. VARIwise: A general-purpose adaptive control simulation framework for spatially and temporally varied irrigation at sub-field scale 16. In-line detection of apple defects using three color cameras system 17. Eggshell crack detection using a wavelet-based support vector machine 18. Metamodeling approach to predict friction factor of alluvial channel 19. Forecasting maturity of green peas: An application of neural networks 20. Detecting stink bugs/damage in cotton utilizing a portable electronic nose 21. Automated knot detection with visual post-processing of Douglas-fir veneer images 22. GIS-based multi-criteria evaluation to land suitability modelling for giant prawn (Macrobrachium rosenbergii) farming in Companigonj Upazila of Noakhali, Bangladesh 23. Spatial analyses to evaluate multi-crop yield stability for a field 24. A segmentation algorithm for the delineation of agricultural management zones 25. On-the-go VisNIR: Potential and limitations for mapping soil clay and organic carbon 26. Lamina2ShapeAn image processing tool for an explicit description of lamina shape tested on winter wheat (Triticum aestivum L.) 27. Implementing sugarcane quality-based payment systems using a decision support system 28. Capacitive sensor for chopped maize throughput measurement 29. An image processing algorithm for detecting in-line potato tubers without singulation 30. Simulation modeling and analysis for production scheduling using real-time dispatching rules: A case study in canned fruit industry Short communciation 31. Radiofrequency applications in grapevine: From vineyard to web 更多农业工程核心文献题录信息，请登录农业工程学科知识库查询： http://aekd.cau.edu.cn
Title: A unified constitutive model for both clay and sand with hardening parameter independent on stress path Author: Yao, Y. P.; Sun, D. A.; Matsuoka, H. Source: Computers and Geotechnics, 2008, 35(2): 210-222 Abstract: A unified constitutive model for both clay and sand under three-dimensional stress conditions is derived from the modified Cam-clay model, by taking the following two points into consideration. First, a transformed stress tensor based on the SNIP (spatially mobilized plane) criterion is applied to the Cam-clay model. The proposed model consistently describes shear yielding and shear failure and combines critical state theory with the SMP criterion for clay. Secondly, a new hardening parameter, which is independent of the stress path, is derived in order to develop a unified constitutive model for both clay and sand. It not only describes the dilatancy for lightly to heavily dilatant sand, but also reduces to the plastic volumetric strain for clay. The validity of the hardening parameter is confirmed by the test results of triaxial compression and extension tests on sand under various stress paths. Only five conventional soil parameters are needed in the proposed model.
标签: Computers
