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).     

Minimum switching control for adaptive tracking

The switching adaptive control method has been used for quite a few years to solve the adaptive stabilization and model reference adaptive control problems. However, a serious problem with the switching control method is that the number of ‘candidate’ controllers can potentially be very large, especially for multi‐input–multi‐output systems. In this paper, we consider a class of minimum‐phase multi‐input–multi‐output plants with some mild compactness assumptions. Given any polynomial reference input, we provide a switching control law which guarantees exponentially stability of the closed‐loop system with exponential tracking performance. The main contribution of the paper is that we give the minimum number of candidate controllers required for switching. In particular, the number is equal to 2 for single‐input–single‐output plants (one for each sign of the high‐frequency gain), and is equal to 2^m for m‐input–m‐output plants. That is, the number is independent of the degree and the relative degree of the plant. Copyright © 2006 John Wiley & Sons, Ltd.     

Influence of melt superheat on breakup process of close-coupled gas atomization

In close-coupled gas atomization（CCGA）, the influences of melt superheat on breakup process are fundamental to obtain desired or finer powder. Based on a series of Cu atomization experiment under different superheating conditions, the influences of melt superheat on breakup process were studied. Experimental results indicate that as the melt superheat is increased to 150, 200, 250 and 300 K, the mean particle size （D50） decreases consequently to 34.9, 32.3, 30.9 and 19.7 μm. Theoretical analysis reveals that the primary breakup and secondary breakup processes are close coupled, and the melt superheat radically influences the melt properties, and plays a crucial role on governing the filming process of primary breakup and the atomization modes of secondary breakup. There exists a strong nonlinear decrease of contact angle of melt to nozzle orifice wall when the superheat is increased fi＇om 250 K to 300 K, leading to a marked fall of the film thickness formed in primary breakup, and D50 of copper powders is therefore sharply reduced. However, the log-normal distribution feature of particle size has not been substantially improved.     

THE RELATIONSHIP BETWEEN HAZE AND THE SIZE OF PARTICLES IN BEER

Haze measurements have been obtained for suspensions of polystyrenelatex particles of known diameter using two light scattering instruments which measure at angles of 90° and 13° respectively. The results agree well with the theory of light scattering and demonstrate the significant effects of particle size and angle of detection upon the instrumental values for haze. This information has been used to correlate the particle size distributions of a number of beers, as measured by Coulter Counter, with the corresponding, measured haze values.     

自适应相位制中波同步广播及现场试验

在本试验中，采用智能同步广播激励器和ＣＣＴＶ传输的１ＭＨｚ标频，实现了中波同步广播同频保护率趋于０ｄＢ．并提出了自适应相位跟踪同步的概念。     

激光跟踪测距仪在体育领域中的应用

介绍了激光的特点及激光跟踪测距仪的工作原理 ,在此基础上 ,设计了一种激光跟踪测距系统 ,对该系统的组成及主要部件进行了阐述 ,给出了该系统的主要性能数据 ,并对该系统在体育领域中的应用前景作了展望。     

减少激光粒度仪系数矩阵数目的方法

通过分析激光粒度仪的系数矩阵的计算公式．指出不同焦距下的各个系数矩阵之间存在着简单的比例关系，即可由一个焦距对应的系数矩阵推得另一个焦距的系数矩阵，从而可减少仪器测量所需的系数矩阵数目。这一关系式已由数值计算及对标准颗粒的实测得到证实。     

采用信息融合技术的IR／MMW复合导引头的目标跟踪

从误差测量环节入手，基于IR／MMW双模结构，采用信息融合处理技术提高其估计跟踪精度，最终达到降低制导误差，提高武器性能的目的，仿真结果验证了该方法的有效性。     

压力对Fe－29wt％Ni合金超细微粒特性的影响

利用蒸发冷凝法，制备了不同平均粒径的Ｆｅ－２９ｗｔ％Ｎｉ合金超细微粒。在不同压强下，将超细微粒压制成片。随压强增大，马氏体体积分数和比饱和磁化强度σｓ明显增大，而矫顽力Ｈｃ呈线性下降。压力效应与平均粒径ｄ大小密切相关     

四路激光跟踪测量系统最佳测量区域和系统自标定

研究了系统最佳布局下的最佳测量区域问题,给出了几何精度衰减因子PDOP在三维空间内的变化规律。通过计算机仿真研究了最佳测量布局对系统自标定的影响规律,指出最佳测量布局中的标称配置对系统自标定精度的影响最小,同时这种布局有着最小的几何精度衰减因子。