组合DEA方法与成熟度模型对项目效益的评价

为全面考虑资金、管理决策能力等因素对项目效益的影响，本运用数据包络分析与项目成熟度模型结合的方法来对企业各个项目之间的相对效益进行评价，应用结果表明该评价方法对于企业资源的最优配置、提高总体效益是十分有用的。     

一种简易云雾室的制作

本文利用自制云雾室把微观粒子的运动转化为宏观现象，从而供实验观察和研究。     

Stationary Distribution Function Estimation for Ergodic Diffusion Process

The problem of nonparametric stationary distribution function estimation by the observations of an ergodic diffusion process is considered. The local asymptotic minimax lower bound on the risk of all the estimators is found and it is proved that the empirical distribution function is asymptotically efficient in the sense of this bound.     

一种新型的二元光学器件——多位相光束分束器的制作

本文报道了用于多光束分束器的反射式16位相值二元光学器件的制作。该二元光学器件把一束光束分成5×5光束阵列。测量的衍射效率为76.16%,接近理论设计值79.68%。该二元光学器件的有效孔径为10mm×10mm。     

着生刚毛藻处理富营养化湖泊水

分别研究了室内和露天条件下在鹅卵石上着生的刚毛藻Cladophora oligoclona对富营养化湖水中氮(N)和磷(P)的净化效果及其对水华藻类生长的抑制能力,同时对处理后湖水的藻类生长潜力进行了测试.结果显示,刚毛藻在原始浓度总氮(TN)10.512 mg/L和总磷(TP)0.856 mg/L的富营养化湖水中能维持正常的生长代谢,并能有效去除水体中的N、P养分.在室内12 d培养期间,刚毛藻对TN、氨氮(NH4-N)、TP和无机磷(PO4-P)的平均去除率分别达53.13%,44.40%,35.71%和30.53%.在室外6 d培养期间,刚毛藻对TN、NH4-N、TP和PO4-P的日均减少量分别为1.643 5±0.413 9,1.350 3±0.352 4,0.113 7±0.041 1,0.074 2±0.033 0 mg/L,总去除率分别高达93.81%,94.62%,79.67%和77.66%.刚毛藻对水华微囊藻生长的抑制率达99.63%,处理后湖水的藻类生长潜力较原湖水下降了40.17%.据此认为,刚毛藻在净化污染水体、修复受损湖泊及防治水体富营养化等方面具有潜在的应用前景.     

饲喂频率对鲈鱼生长及体生化成分的影响

选取同一种饵料设置1次·d-1、2次·d-1、3次·d-1、4次·d-14个饲喂频率,采用静水连续充气养殖系统,在盐度为26.0%～27.0%、温度为26～30℃条件下对鲈鱼(85.95±2.04)g进行为期40d的生长实验.结果表明:(1)饲喂频率影响鲈鱼的生长是由食物转化率和摄食率的提高共同引起的.(2)水分含量随饲喂频率的增高而保持不变;蛋白质含量随饲喂频率的增加,基本保持不变;脂肪含量随饲喂频率的增高而明显减少;灰分含量随饲喂频率的增多而明显增加.(3)鲈鱼的适宜饲喂频率为2次·d-1.     

光强一定时饱和光电流随入射光频率的变化关系辨析

对光电效应实验中饱和光电流随入射光频率变化关系的几种谬误进行了辨析，给出了光强一定时饱和光电流随入射光频率变化的正确规律并作了解释。     

A technique to construct symmetric variable-stepsize linear multistep methods for second-order systems

Some previous works show that symmetric fixed- and variable-stepsize linear multistep methods for second-order systems which do not have any parasitic root in their first characteristic polynomial give rise to a slow error growth with time when integrating reversible systems. In this paper, we give a technique to construct variable-stepsize symmetric methods from their fixed-stepsize counterparts, in such a way that the former have the same order as the latter. The order and symmetry of the integrators obtained is proved independently of the order of the underlying fixed-stepsize integrators. As this technique looks for efficiency, we concentrate on explicit linear multistep methods, which just make one function evaluation per step, and we offer some numerical comparisons with other one-step adaptive methods which also show a good long-term behaviour.

     

Indoor radon measurements in dwellings of four Saudi Arabian cities

An indoor radon survey of a total of 269 dwellings, with one dosimeter per house, distributed in four Saudi Arabian cities was carried out. The objective of this survey was to carry out indoor radon measurements of two cities in the Eastern Province, Khafji and Hafr Al-Batin and to compare this with two cities in the Western Province, Al-Madina and Taif. The survey provides additional information about indoor radon concentrations in Saudi Arabia. The results of the survey in these cities showed that the overall minimum, maximum and average radon concentration were 7,137 and 30 Bqm⁻³, respectively. The lowest average radon concentration (20 Bqm⁻³) was found in Hafr Al-Batin, while the highest average concentration was found in Khafji (40 Bqm⁻³).     

Benson真有效意义下集值优化的广义最优性条件

本文引入了关于集值映射的α-阶Clarke切导数、α-阶邻接切导数及α-阶 伴随切导数的概念,借此建立了约束向量集值优化Benson真有效解导数型的Kuhn- Tucker条件.