充油NR在轿车轮胎胎面中的应用

由于技术革新、消费者偏爱和政府法规使轮胎工业保持了最大的ＮＲ消费行业地位。轮胎子午化、冬用轮胎和燃料经济的发展，增加了ＮＲ在轿车轮胎中的消耗量。全天候轮胎的出现，提高了ＮＲ作为一种胎面材料的竞争力。在胎面胶中用充油ＮＲ（ＯＥＮＲ）部分取代充油ＳＢＲ（ＯＥＳＢＲ），使得轮胎滚动阻力降低和冰面牵引性提高，同时保持了湿牵引性。已证明，掺用ＯＥＮＲ的胎面在冬季和夏季的耐磨性能可与全ＳＲ胎面相匹敌。     

Two-Phase Flow Visualization in Chevron and Bumpy Style Flat Plate Heat Exchangers

Adiabatic flow visualization in a chevron plate, a 1:1 aspect ratio bumpy plate, and a 2:1 aspect ratio bumpy plate heat exchangers were investigated for vertical upward flow with R134a. Qualities ranging from 5% to 90% and mass fluxes of 60, 90, and 125 kg/m²-s were investigated. The flow visualization experiments were conducted at a 10°C inlet temperature. Four flow regimes were observed for the flat plate geometries investigated: bubbly flow, rough annular flow, smooth annular flow, and mist flow. The four flow regimes are mapped out on a mass flux versus quality basis for each geometry. The chevron geometry was seen to undergo flow transitions at lower qualities and mass fluxes than the bumpy plate geometries, and the 2:1 aspect ratio bumpy plate geometry was seen to undergo flow transitions at lower qualities and mass fluxes than the 1:1 aspect ratio bumpy plate geometry.     

Finite element modelling of the effect of non-metallic inclusions in metal forming processes

The presence of non-metallic inclusions can result in material failure during the metal forming process, or lead to a serious deterioration of the quality of the final product. Understanding the effects of inclusions during metal forming is therefore an important step towards predicting the behaviour of inclusions and subsequently minimising their consequences. To achieve this understanding the authors incorporated non-metallic inclusions into a finite element (FE) simulation of metal forming. The chosen metal forming process was rod drawing, the chosen inclusion material aluminium oxide (Al₂O₃) and the chosen inclusion shape spherical. Real rod drawing experiments were also designed with Al₂O₃ spheres embedded in a steel rod in order to compare experimental and simulated results. Specifically, from the experiments carried out the changes of the rod around the inclusion were investigated and the findings compared with the finite element simulation results of an equivalent model. The FE simulation of the experiments considered specifically the fracturing of brittle inclusions. A concept allowing the fracturing of brittle inclusions by means of finite element method is described. Experimental results from fourpoint bending tests, and tensile tests, for Al₂O₃ ceramic bodies were used to calibrate the simulation. Further experiments involved the crushing of Al₂O₃ spheres where the force necessary to achieve crushing was measured and compared with the results of the calibrated FE simulation. It is demonstrated that the intended FE method for the simulation of brittle fracture of inclusions can be used with good accuracy.     

Basic modelling of direct electrochemical cooling

A direct electrochemical refrigeration cycle (DERC) uses the entropy change of an electrochemical reaction to produce cooling. The cycle is Carnot limited. The electricity recycled in the DERC is much larger than the energy input to the system. Therefore, the system is sensitive to small inefficiencies in the internal energy cycling. In addition, a DERC is modelled assuming that the electrochemical cells have a constant internal resistance. By modelling the electrodes as parallel plates, an optimal channel size on the order of tens of microns can be computed depending on the electrical resistivity and viscosity of the electrolyte. The maximum cooling flux is on the order of 1000 W m⁻². Copyright © 2006 John Wiley & Sons, Ltd.     

功率因数校正也是马达效率的关键之一

提高马达功效已成为了业界关注的焦点,随着节能在技术上能够实现,而经济的发展也逼切要求,不论是个人、企业还是政府机构都对节能这一话题兴趣日隆.业界在马达控制算法和实现马达驱动的高成本效益电子器件方面取得了多项成果,而这正引发起一场革命,延及几乎每一个马达市场.     

Feeding the World Today and Tomorrow: The Importance of Food Science and Technology

by Philip E. Nelson, 2007 World Food Prize Laureate; Professor Emeritus, Food Science Dept., Purdue Univ. Just as society has evolved over time, our food system has also evolved over centuries into a global system of immense size and complexity. The commitment of food science and technology professionals to advancing the science of food, ensuring a safe and abundant food supply, and contributing to healthier people everywhere is integral to that evolution. Food scientists and technologists are versatile, interdisciplinary, and collaborative practitioners in a profession at the crossroads of scientific and technological developments. As the food system has drastically changed, from one centered around family food production on individual farms and home food preservation to the modern system of today, most people are not connected to their food nor are they familiar with agricultural production and food manufacturing designed for better food safety and quality. The Institute of Food Technologists—a nonprofit scientific society of individual members engaged in food science, food technology, and related professions in industry, academia, and government—has the mission to advance the science of food and the long‐range vision to ensure a safe and abundant food supply contributing to healthier people everywhere. IFT convened a task force and called on contributing authors to develop this scientific review to inform the general public about the importance and benefits of food science and technology in IFT's efforts to feed a growing world. The main objective of this review is to serve as a foundational resource for public outreach and education and to address misperceptions and misinformation about processed foods. The intended audience includes those who desire to know more about the application of science and technology to meet society's food needs and those involved in public education and outreach. It is IFT's hope that the reader will gain a better understanding of the goals or purposes for various applications of science and technology in the food system, and an appreciation for the complexity of the modern food supply. Abstract: This Institute of Food Technologists scientific review describes the scientific and technological achievements that made possible the modern production‐to‐consumption food system capable of feeding nearly 7 billion people, and it also discusses the promising potential of ongoing technological advancements to enhance the food supply even further and to increase the health and wellness of the growing global population. This review begins with a historical perspective that summarizes the parallel developments of agriculture and food technology, from the beginnings of modern society to the present. A section on food manufacturing explains why food is processed and details various food processing methods that ensure food safety and preserve the quality of products. A section about potential solutions to future challenges briefly discusses ways in which scientists, the food industry, and policy makers are striving to improve the food supply for a healthier population and feed the future. Applications of science and technology within the food system have allowed production of foods in adequate quantities to meet the needs of society, as it has evolved. Today, our production‐to‐consumption food system is complex, and our food is largely safe, tasty, nutritious, abundant, diverse, convenient, and less costly and more readily accessible than ever before. Scientific and technological advancements must be accelerated and applied in developed and developing nations alike, if we are to feed a growing world population.     

International technology-oriented agreements to address climate change

Much discussion has surrounded possible alternatives for international agreements on climate change, particularly post-2012. Among these alternatives, technology-oriented agreements (TOAs) are perhaps the least well defined. We explore what TOAs may consist of, why they might be sensible, which TOAs already exist in international energy and environmental governance, and whether they could make a valuable contribution to addressing climate change. We find that TOAs aimed at knowledge sharing and coordination, research, development, or demonstration could increase the overall efficiency and effectiveness of international climate cooperation, but are likely to have limited environmental effectiveness on their own. Technology-transfer agreements are likely to have similar properties unless the level of resources expended is large, in which case they could be environmentally significant. Technology-specific mandates or incentives could be environmentally effective within the applicable sector, but are more likely to make a cost-effective contribution when viewed as a complement to rather than a substitute for flexible emissions-based policies. These results indicate that TOAs could potentially provide a valuable contribution to the global response to climate change. The success of specific TOAs will depend on their design, implementation, and the role they are expected to play relative to other components of the policy portfolio.     

Cardiac outcome in patients with subarachnoid hemorrhage and electrocardiographic abnormalities

OBJECTIVE: Approximately 25% of patients with subarachnoid hemorrhage (SAH) have electrocardiographic (ECG) abnormalities consistent with myocardial ischemia or myocardial infarction (MI), and their cardiac prognosis remains unclear. The objective of this study was to determine the cardiac and all-cause mortality rate of a series of patients with SAH with ECG changes consistent with ischemia or MI. METHODS: Using an existing database of patients with SAH and predetermined ECG criteria for ischemia or MI, a study group of patients with abnormal ECG results within 3 days of presentation and before aneurysm surgery was identified. Database patients without abnormal ECG results served as a control group. Cardiac mortality, defined as death resulting from arrhythmia, congestive heart failure, or cardiogenic shock, was assessed by chart review. RESULTS: Of 439 patients with SAH in the database, 58 met the criteria for the study group. Forty-one of these patients were treated neurosurgically. No deaths resulting from cardiac causes occurred, and 20 patients died as a result of noncardiac causes. In a multivariable analysis, age older than 65 years and Hunt and Hess grade of at least 3 were predictive of all-cause mortality. ECG abnormalities, however, were not a statistically significant predictor. CONCLUSION: In patients with SAH and ECG readings consistent with ischemia or MI, the risk of death resulting from cardiac causes is low, with or without aneurysm surgery. The ECG abnormalities are associated with more severe neurological injury but are not independently predictive of all-cause mortality.     

Exploring social capital in the construction firm

Social capital, which derives from the network of social relationships in which people are embedded, has increasingly been seen as a resource that firms can use and which enables them to tap into and exploit their intellectual capital and, thus, release the firm's innovative potential. Yet, in project-based organizations, there remain many barriers and pitfalls in any attempt to exploit human resource potential in this way. In particular, the one-off nature of project tasks and teams and the importance of individuals' embodied knowledge and learning ensure that while social capital may assume greater importance, at the same time its capture becomes more problematic. This paper presents findings from a research project undertaken in the UK that explores knowledge management for project-based learning across a range of industrial sectors, including construction. Drawing upon a case study analysis of project-based learning in a construction firm, it applies an already established framework to examine the paradoxes that arise when attempts are made to mobilize social capital.