Recent developments of high-performance NEOMAX magnets

For further improvement in achieving extremely high magnetic properties of Nd- Fe- B sintered magnets, extensive investigation has been done to densify the magnet up to the theoretical value, to increase the volume fraction of the Nd ₂Fe₁₄B matrix phase, and to achieve a high degree of alignment. By controlling chemical composition and the amount of constituent phases,improving particle size distribution, and adopting the isostatic pressing method to get better alignment of fine particles, we have succeeded in obtaining a high-performance magnet having residual flux density (B_r) of 1.495 T (14.95 kG), maximum energy product [(BH)_max] of 431 kj/m³ (54.2 MGOe), and intrinsic coercivity (iH_c) of 845 kA/m (10.62 kOe).     

Differentiation between epigeic and hypogeic fauna in gravel streams

The ‘hyporheic zone’ is described. According to the classical definition, water below the sediment surface is groundwater and the hyporheic interstitial zone is part of the phreatic system. This ignores the vertical distribution of the epigeic benthic fauna. The uppermost layer of the sediment (bed sediments) of the hyporheic zone is dominated by epigeic faunal elements and is therefore part of the surface system. In contrast to hypogeic species, the depth penetration of epigeic species is limited. Possible explanations are discussed.     

Influence of heat transfer on anodic oxidation of aluminium

The influence of convective heat transfer on constant current density anodizing of aluminium in sulfuric acid has been examined in a wall-jet electrode reactor. The uniformity of the anodic film thickness is related to the local electrode temperature distribution, which is dependent on the convection. The higher the local temperature, the greater the local oxide thickness. An increased local temperature enhances local field assisted oxide dissolution at the pore bases, and consequently acts to increase the local current density. At relatively high current densities, local features develop on the electrode surface, accompanied by high initial, local temperature rises. The relevance of such local features, limiting useful oxide growth, is considered further.     

太阳能热风发电技术研究进展

介绍了太阳能热风发电的产生背景、技术原理和特点。太阳能热风发电能够实现由太阳能到空气动能,最终到电能的转变,具有环保无污染、运行维护简单、缓解常规能源消耗等特点。简要介绍世界上第1座试验性质的太阳能热风发电站。对太阳能热风发电技术相关研究历程从试验研究和理论研究2个方面做了综述,重点介绍了澳大利亚电站的建设进展及最新相关学术研究进展,包括过渡段理论及试验研究、系统数值模拟和太阳能热风发电技术在高山地区的应用等。介绍我国太阳能资源情况,指出我国太阳能资源丰富,适合建造大型太阳能热风发电站。     

文昌A凹陷油气成藏特征与分布规律探讨

文昌A凹陷位于珠江口盆地西部,是一个发育文昌组和恩平组两套湖相烃源岩复合成藏的油气区。根据特征生物标志化合物与碳同位素组成的油岩对比结果,可将文昌A凹陷发现的原油划分为两类,即文昌Ⅱ型和恩平型,前者来自文昌组浅湖相烃源岩,后者源于恩平组湖相烃源岩;天然气主要源于恩平组烃源岩,也可能有文昌组烃源岩凝析气或裂解气的贡献。文昌A凹陷油气两期成藏,早期成油,晚期聚气及轻质油,其油气分布主要受烃源岩有机相、热演化程度和运移分馏作用等因素的控制,凹陷中部以气为主,凹陷边缘气油共存,而凸起上以油为主。     

用微机计算电子衍射径向分布函数

本文介绍用微机计算非晶态高聚物电子衍射径向分布函数(RDF)。运用二次样条函数分段拟合及傅氏积分的数学方法,通过 BASIC 程序,只要输入初始实验数据即可自动解算且连续得到与各运算阶段相应的曲线图及其运算结果.     

Techniques for estimating test length under random test

When a circuit is tested using random or pseudorandom patterns, it is essential to determine the amount of time (test length) required to test it adequately. We present a methodology for predicting different statistics of random pattern test length. While earlier methods allowed estimation only of upper bounds of test length and only for exhaustive fault coverage, the technique presented here is capable of providing estimates of all statistics of interest (including expected value and variance) for all coverage specifications.Our methodology is based on sampling models developed for fault coverage estimation [1]. Test length is viewed as awaiting time on fault coverage. Based on this relation we derive the distribution of test length as a function of fault coverage. Methods of approximating expected value and variance of test length are presented. Accuracy of these approximations can be controlled by the user. A practical technique for predicting expected test length is developed. This technique is based on clustering faults into equal detectability subsets. A simple and effective algorithm for fault clustering is also presented. The sampling model is applied to each cluster independently and the results are then aggregated to yield test lengths for the whole circuit. Results of experiments with several circuits (both ISCAS '85 benchmarks and other practical circuits) are also provided.This work was done while the author was with the Department of Electrical Engineering, Southern Illinois University, Carbondale, IL 62901.     

轴对称问题线元上分布奇点的诱导速度势和诱导速度

本文给出轴对称问题线元上高次分布源和偶极在无界域中的诱导速度势和诱导速度的计算公式,可供用分布奇点法求解轴对称势流问题时参考.     

Determination and Health Implication of the Erucic Acid Content of Broccoli Florets, Sprouts, and Seeds

The erucic acid content of broccoli florets, sprouts, and seeds was found to be about 0.8, 320, and 12100 mg/100 g, respectively. Using the erucic acid limit established for canola oil in the U.S.A. and Canada as a guideline, the estimated dietary intake of erucic acid from florets and sprouts was considered of little consequence, whereas in seeds a relatively small amount (about 35 g/wk) equaled our calculated exposure limit for erucic acid. Additionally, the most complete fatty acid distribution yet published for the various forms of broccoli are presented.     

尾流受扰下复杂体形高层建筑的风压分布特性

本文结合汕头粤东信息大厦的风洞试验,详细分析了复杂结构断面建筑物在其尾流受到下游结构干扰下的风压分布特性。试验表明:处于受扰物体尾流边界上的施扰物体可以降低来流在受扰物体上的分离速度,从而使最大负压系数降低。当施扰物体处于被扰物体尾流边界的某些位置时,被扰物体表面的最大负压系数受到显著影响,最多可降低45%。文中还对典型断面结构进行了进一步的试验研究,在验证以上的结论同时,试验结果也显示,施扰建筑位于被扰结构临近的较大区域,其风压增大15%以上,最大可增大39%。本文所得的一些结论可为相应的工程提供参考。