二维全息光子晶体禁带展宽方法

讨论了二维复周期全息光子晶体禁带展宽的方法,二维复周期全息光子晶体可以使禁带成倍展宽.此外发现二维全息光子晶体中,除原来预期的禁带外,还出现了附加的禁带.当记录光波的入射角小于某个临界值,并且满足一定数值时,附加的禁带会使二维禁带进一步展宽;而当入射角超过临界值时,禁带会消失,这时禁带反而会变窄.这一现象对制作二维宽带隙光子晶体具有指导意义.     

THE DESIGN AND STATISTICAL ANALYSIS OF EXPERIMENTS TO MEASURE HUMAN PERFORMANCE TIMES

In this paper, a managerial perspective is applied to the traditionally technological problem of yarn wastage in the carpet manufacturing sector. An empirical investigation is carried out to detect the errors arising in the spinning and tufting parts of the production process. A simulation package is then developed to investigate how such errors determine the overall level of waste yam remaining after production.

To reduce the level of waste, several strategies involving the use of spare cones are identified. These are evaluated and compared using the simulation as a test-bed.     

7xxx系铝合金热处理的进展

7xxx系合金是基于Al-Zn-Mg（-Cu）系的可热处理的锻铝合金，广泛应用于高性能航空结构和运输部件。除了受成分、铸造和形变热处理影响外，材料性能的平衡明显受到其所经历的热处理方式的影响。描述了均匀化、固溶处理、淬火、时效对7xxx系高强合金组织和性能的影响。总结了在Monash大学进行的有关厚板产品的生产工艺，包括从均匀化到最终的时效处理，以及通过控制微观组织特征，比如弥散体、粗粒子、精细析出相、晶粒结构和晶界特征，来实现组织与性能的平衡。重点陈述了相关方法，如通过高温热处理溶解不需要的粗粒子、基于连续冷却析出行为的淬火敏感性变化、通过实验与建模来研究时效包括一步时效、两步时效、三步时效。对每种情况下的组织与性能都进行研究。     

Transparency and parametric generation in a four-level system † Reviewing of this paper was handled by a member of the Editorial Board.

We analyse two distinct nonlinear phenomena in a four-level quantum system having a tripod configuration. First, we show that the system can become transparent at two different frequencies of a probe laser field. The potential for parametric generation in this medium is also investigated. We show that, if the system is prepared in a coherent superposition of two or three of the lower levels, one or two new fields can be generated.     

On pulse propagation in a coherently prepared multi-level medium † Reviewing of this paper was handled by a member of the Editorial Board.

The propagation dynamics of N laser pulses in a coherently prepared (N +1)-level quantum medium is investigated. A N -photon Beer's law is presented and a generalized Beer's length defined, which determines the decay of the laser pulses in the medium. A general propagation relation for the N laser pulses which holds for long distances is also given.     

Controlling Nitrate Leaching in Water Supply Catchments

S prings from a catchment to the north east of Bath to provide up to 80 per cent of the water supply to a population of 96 000. A review in 1984 suggested that within a few years nitrate concentrations in these sources could exceed the limit for drinking water (11.3 mg N/1). Nitrate was being leached from agricultural land and when an opportunity arose to alter the largely arable farming on part of the catchment, guidelines were devised to reduce nitrate leaching. This paper describes the guidelines and the effects of their implementation.     

基于岸基实测数据的FY-3A近红外通道海洋大气水汽反演

利用全自动太阳光度计(CE-318)野外定点长时间序列现场观测数据,验证传统大气水汽反演算法,结果表明,反演结果精度较低,不适于该研究区域大气水汽含量反演.因而给出了近红外波段大气水汽含量探测的原理,对自主卫星FY-3A中分辨率成像光谱仪MERSI(Medium Resolution Spectral Imager)反演大气水汽含量算法作了推导、分析.基于长时间序列现场观测数据集,建立了局地化的FY-3A海洋大气水汽反演算法,并用于研究区实际大气水汽含量反演.通过双通道比值法和三通道比值法反演结果与现场实测数据比较,得出以下结论:模型受下垫面反射率影响较大;三通道比值法较双通道比值法反演结果精度更高,双通道比值法误差为16.1%,三通道比值法误差为14.3%;实测数据验证和改进后算法精度更高.     

COMPACTION CHARACTERISTICS OF AGGLOMERATED COFFEE DURING TAPPING

Three brands of instant coffee were used as model agglomerated powders. They were exposed to compaction in a tap density tester. Experiments were done confining samples of instant coffee in graduated cylinders with several diameters, i.e., 1.6, 2.0 and 2.4 cm; and different product heights, i.e., 3.2, 6.3, and 12.5 cm. Increased attrition was noticed with the number of tappings, which ranged from 0 to 10,000 taps. Changes in bulk density were fitted to two-parameter models used for compaction of food powders, using nonlinear regression. New three and four-parameter models were proposed, and their fit to experimental data was also examined. The fit of these new models was better than that of previous ones, indicating that the combined effect of attrition and compaction cannot be properly described by models containing less than three parameters. The container diameter, product height, and particle size were found to affect the parameters' estimates for the models examined.     

采矿巷道MATLAB有限元仿真及ANSYS对比分析

结合采矿巷道进行MATLAB有限元仿真,并通过ANSYS进行对比,两者计算数值相差不足1%,故程序可应用于实际计算,分析了巷道应力变形情况,得出了具体的结论,并针对拱顶至围岩上表面、拱腰至右侧外表面的水平围岩得出了规律曲线.