Identifying the efficiency status in network DEA

Data envelopment analysis (DEA) is commonly employed to evaluate the efficiency performance of a decision making unit (DMU) that transforms exogenous inputs into final outputs. In such a black-box DEA approach, details of an internal production process of the DMU are typically ignored and hence the locations of inefficiency are not adequately provided. In view of this, DEA researchers have recently developed various network approaches by looking into the black box, where the inputs that enter the box and the outputs that come out of it are only considered. However, most of these network approaches evaluate divisional efficiency by using an optimal solution of their respective optimization problem. If such an optimal solution is used in the case when there are multiple optima, then managerial guidance based on this solution alone may be inappropriate because more appropriate targets from the viewpoint of management may be ignored. Taking this fact into account, therefore, we propose a network approach for identifying the efficiency status of each DMU and its divisions. This approach provides a practical computational procedure.     

应用数码相机进行绿肥翻压后春玉米氮素营养诊断和产量预测

在绿肥翻压条件下,常规的玉米氮素营养诊断技术存在耗时、费力和可靠性差的缺点。基于数码相机的可见光光谱技术已被广泛应用于大田作物的氮素营养诊断,但尚未见应用于绿肥翻压后的玉米氮素营养诊断。为评价利用图像处理技术进行绿肥翻压后玉米氮素营养诊断和玉米产量预测的可行性,设置了不同施氮水平下的绿肥翻压试验,利用数码相机获取不同生育期玉米冠层数字图像,分析了玉米冠层图像色彩参数与氮素营养诊断指标和成熟期籽粒产量之间的关系。结果表明,绿肥翻压显著改善了玉米的氮素营养,不同生育期的玉米叶绿素含量(SPAD值)、地上部生物量和吸氮量均高于单施化肥处理;绿肥翻压处理下,玉米冠层光谱指数与氮素营养指标间的相关性较单施化肥处理低,且其相关性在不同的生育期有较大变异,其中,12叶期(V12)的蓝光标准化值(B/(R+G+B))与灌浆期(R4)的红光标准化值(R/(R+G+B))与植株氮营养指标相关性较好,二者均与玉米产量间呈显著直线回归关系,回归系数分别为45%和46%。因此,数字图像技术在进行绿肥翻压后玉米氮素营养的诊断和产量预测方面具有应用潜力,但应注意诊断时期和关键指标的选择。     

水溶液中二氧化碳电还原技术的发展现状、挑战及对策

二氧化碳(CO₂)电化学还原利用CO₂生产低碳燃料,能够实现可再生能源存储同时降低温室气体排放对环境的负面影响,因而成为了近年里一个甚受瞩目的研究与开发热点. 尽管以往科学家关于催化剂活性、产物选择性以及反应机理的基础研究已做了广泛的报道,但对催化稳定性和电化学反应器系统的设计及实用性方面还未给予充分重视. 本文针对影响低温水溶液中二氧化碳电化学还原技术实用化的上述两个重要因素, 从技术应用需求角度出发,在概述发展现状基础上,总结归纳了主要存在的技术挑战,对未来研究方向提出了建议性对策.     

基于多变量统计分析的冬小麦长势高光谱估算研究

利用高光谱分析技术实现冬小麦长势的准确、无损监测具有重要的实践意义。基于连续两年的氮素运筹试验,通过获取叶面积指数(LAI)、地上干生物量(AGDB)、地上鲜生物量(AGFB)、植株含水量(PWC)、叶绿素密度(CH.D)和氮素积累量(ANC)六个冬小麦长势指标及冬小麦冠层高光谱,引入主成分分析法(PCA)构建可表征冬小麦长势的综合长势指标(CGI),并结合偏最小二乘回归法(PLSR)构建CGI的高光谱估测模型。结果表明,除植株含水量外,其他长势指标与所构建的CGI都达到极显著水平,表明利用CGI可以表征各长势指标信息。对比CGI和其他各长势指标的PLSR模型表现可知,CGI光谱监测模型表现最优(R2=0.802,RMSE=1.268,RPD=2.015),也具有较高的预测精度和稳健度(R2=0.672,RMSE=1.732,RPD=1.489)。表明基于PCA方法所构建的CGI可以表征冬小麦长势,利用PLSR方法可以实现对冬小麦长势的准确监测,且监测效果要优于单一的冬小麦长势指标。     

A UoI-Optimal Policy for Timely Status Updates with Resource Constraint

Timely status updates are critical in remote control systems such as autonomous driving and the industrial Internet of Things, where timeliness requirements are usually context dependent. Accordingly, the Urgency of Information (UoI) has been proposed beyond the well-known Age of Information (AoI) by further including context-aware weights which indicate whether the monitored process is in an emergency. However, the optimal updating and scheduling strategies in terms of UoI remain open. In this paper, we propose a UoI-optimal updating policy for timely status information with resource constraint. We first formulate the problem in a constrained Markov decision process and prove that the UoI-optimal policy has a threshold structure. When the context-aware weights are known, we propose a numerical method based on linear programming. When the weights are unknown, we further design a reinforcement learning (RL)-based scheduling policy. The simulation reveals that the threshold of the UoI-optimal policy increases as the resource constraint tightens. In addition, the UoI-optimal policy outperforms the AoI-optimal policy in terms of average squared estimation error, and the proposed RL-based updating policy achieves a near-optimal performance without the advanced knowledge of the system model.     

A new model for classifying inputs and outputs and evaluating the performance of DMUs based on translog output distance function

In conventional data envelopment analysis it is assumed that the input versus output status of each chosen performance measures is known. In some conditions finding a statue of some variables from the point view of input or output is very difficult; these variables treat as both an input and output and are called flexible measures. This paper proposes a new model based on translog output distance function for classifying inputs and outputs and evaluating the performance of decision-making units by considering flexible measures. Monte Carlo simulation is applied to evaluate the presented model comparing with that of the recent model found in the literature. The result shows that the measure efficiencies of our model are statistically closer to true efficiencies and have higher rank correlation with true efficiencies. Also results obtained from simulated data show that there are high correlation between our model and that of the recent model.     

广州铁路346名儿童锌营养状况分析

为了解广州铁路地区儿童锌营养水平高低对体格发育的影响，对羊城铁路总公司属下８间托幼所３４６名３～５岁儿童进行了发锌含量及体格发育状况的调查．结果提示，６０名健康组小儿发锌与身高，体重有明显正相关性．身高相关系数为γ＝０．１５０，体重相关系数为γ＝０．３４１．５０名缺锌组儿童身高、体重均低于富锌组儿童，两组身高Ｐ值＜０．０２５，体重Ｐ值＜０．００５，有显著差异．这说明锌作为亚临床营养素之一，与小儿身高、体重休戚相关．锌营养不足，可使小儿生长速度受到抑制，因此，在集体儿童体检时，应注意锌营养状况的检验，以及时纠正锌营养缺乏，避免小儿体格发育受锌缺乏的影响．     

平顶山矿区小学生膳食与营养状况分析

为了解平顶山矿区儿童的营养现状，以便对其膳食指导特别是微量元素的营养指导提供科学依据，整群抽取平顶山矿区某小学住宅生134名，采用5日称重法进行膳食调查；原子吸收光谱法测定血清钙、铁、锌含量。结果表明，蛋白质、热量、Fe、Zn的摄入量可达RNI规定；而Ca的摄入量不足，仅达BNI的45．6％。血清Ca、Zn、Fe值低于正常参考值范围的检出率分别为17．9％、2．3％、1．5％。可见该小学生住宅生钙摄入不足，缺钙现象较为普遍，应调整膳食结构，增加含钙丰富的食物。     

Species as a Relationship

The fact that humans have a special relationship to each other insofar as they belong in the same species is often taken to be a morally relevant difference between humans and other animals, one which justifies a greater moral status for all humans, regardless of their individual capacities. I give some reasons why this kind of relationship is not an appropriate ground for differential treatment of humans and nonhumans. I then argue that even if relationships do matter morally species membership cannot justify a difference in moral status. This has important implications because it removes one barrier to giving animals greater moral status.

国际物理教育研究的现状与动向——基于PRPER近15年物理教育研究论文(2005-2019)的内容分析

以权威期刊PRPER近15年的文章为研究对象,运用内容分析法对国际物理教育研究的现状和动向进行分析.结果表明PRPER论文数量逐年增加,主要聚焦于评价、物理课程与教学、学生和教师的态度和信念等研究主题,涉及力学、电学、量子物理等学科领域.当前国际物理教育研究具有研究方向多样化、重视以学科为基础的教育研究模式和关注信息化...