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.     

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.     

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.     

自适应内模PID控制器在梭式窑温度控制的应用

针对梭式窑温度控制过程存在非线性、时变性和不确定性的情况，设计了基于递推增广最小二乘辨识的自适应内模PID控制器，在实际应用中取得了良好的控制效果。     

Assessing Parents' Involvement In Their Children'S Schooling

ABSTRACT: This paper examines two dimensions of parental involvement with their children's schooling: (1) parent-child interaction with homework in the home and (2) parent-school staff interactions with meetings in the school. The data are drawn from an urban school district of 17,000 students, demographically reflecting many Northern central cities. The random sample consisted of 322 households with one or more children attending grades K-12 in the public schools. The data indicate a significant difference between the two dimensions as well as their relationship to demographic variables, parental attitudes, and school performance. The design allows separate analysis of these variables for siblings. The authors discuss the various definitions of parental involvement and their implications for policy discussions and offer some conclusions regarding the role of central city parents in the schooling of their children.     

PATHOGEN DETECTION IN FOOD MICROBIOLOGY LABORATORIES: AN ANALYSIS OF QUALITATIVE PROFICIENCY TEST DATA, 1999–2007

The objective of this study was to assess laboratories' ability to detect or rule out the presence of four common food pathogens: Escherichia coli O157:H7, Salmonella spp., Listeria monocytogenes and Campylobacter spp. To do this, qualitative proficiency test data provided by one proficiency test provider from 1999 to 2007 were examined. The annual and cumulative 9-year percentages of false-negative and false-positive responses were calculated.
The cumulative 9-year false-negative rates were 7.8% for E. coli O157:H7, 5.9% for Salmonella spp., 7.2% for L. monocytogenes and 13.6% for Campylobacter spp. Atypical strains and low concentrations of bacteria were more likely to be missed, and the data showed no trend of improving performance over time. Percentages of false-positive results were below 5.0% for all four pathogens.

PRACTICAL APPLICATIONS

The results imply that food testing laboratories often fail to detect the presence of these four food pathogens in real food specimens. To improve pathogen detection, supervisors should ensure that testing personnel are adequately trained, that recommended procedures are followed correctly, that samples are properly prepared, that proper conditions (temperature, atmosphere and incubation time) are maintained for good bacterial growth and that recommended quality control procedures are followed. Supervisors should also always investigate reasons for unsatisfactory proficiency test results and take corrective action. Finally, more research is needed into testing practices and proficiency test performance in food testing laboratories.     

美国管理车道对中国城市交通体系影响的研究

对美国管理车道的规划设置、运营经验等进行了研究,阐述了现阶段如何选择适合本国交通状况的管理车道,并将其引入城市交通管理体系,同时指出我国实现管理车道的理论必要性及实践可能性。     

EFFECTS OF BUTYLATED HYDROXYANISOLE (BHA) AND BUTYLATED HYDROXYTOLUENE (BHT) ON GROWTH AND AFLATOXIN PRODUCTION OF ASPERGILLUS FLAVUS

Butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) were applied to six strains of toxigenic and six strains of non-toxigenic Aspergillus flavus in a method similar to antibiotic susceptibility testing. The cultures were examined for growth inhibition, spore formation, pigmentation, and aflatoxin production. BHA (0.005–0.020 g per plate) had an inhibitory effect on growth and toxigenesis of the test organisms, while BHT (0.005–0.020 g per plate) had no visible inhibitory effects. Sporulation of the cultures had no direct relationship with toxigenesis in the presence of BHA. However, pigmentation of the mycelium is directly related to the intensity of fluorescence of the culture under UV. Heating of BHA did not reduce the inhibitory effect of the compound on A. flavus.     

Distribution of Liquid-Solid Heat Transfer Coefficient among Suspended Particles in Vertical Holding Tubes of an Aseptic Processing System

Mass transfer coefficients between sucrose coated particles and water as the suspending fluid, were measured to obtain values of the heat transfer coefficient by analogy with mass transfer. In a vertical holding tube configuration, the mass transfer coefficient spanned considerable range for those particles with comparable residence time. At Reynolds number 26100, the average mass transfer Sherwood number expressed in terms of residence time was Sh= -110.4t+215.1, and it scattered normally with standard deviation 19.2. The results indicated that heat transfer coefficients vary among particles with different residence times and may be significantly different even for particles with the same residence time.     

就业评估管理信息系统的设计与实现

本文作者介绍了就业评估管理信息系统的设计与实现方法 ,并阐述了就业评估指标体系、系统功能模块和技术特色