一种基于Kd-tree射线追踪法的卫星RCS预估方法

针对空间卫星目标的雷达散射截面（RCS）预估问题,提出了一种基于Kd-tree射线追踪法的 改进物理光学（PO）方 法,实现了对具有较强耦合结构的卫星目标电磁特性计算。基于卫星目标的三维面元模型, 建 立了其对应的Kd-tree空间分割描述结构,将其用于射线追踪,结合PO方法就可以得到给定 模型的RCS预估值。数值计算结果表明,改进方法和MoM方法相比,具有相同计算精度但计算 效率高得多,相比单纯PO方法,改进方法也更接近测量值。     

电伴热和高温水伴热的技术经济分析

通过电伴热与高温水伴热在技术性能上的对比,并就大庆石化公司化工三厂1300 m长工艺管线的保温,采用电伴热和高温水伴热两种方案进行了技术经济分析比较,论证了采用电伴热性能可靠,效益显著。     

西气东输二线工程质量监督中射线检澳的质量控制

针对西气东输二线中以射线检测作为检测焊缝内部缺陷的方法为主要手段,按照标准及相关要求,对射线检测单位从人、机、料、法、环等容易影响检测结果的诸多方面进行了阐述,指出工程质量监督中对检测单位质量行为和实体质量进行监督的一些重要环节。     

国家审计能否促进农村脱贫?——基于空间杜宾模型的检验

基于2010—2016年中国省域农村贫困情况数据及国家审计数据,采用空间杜宾模型,在考虑空间滞后效应的条件下,对国家审计治理与农村脱贫之间的关系进行了经验识别与政策讨论。研究结果表明,我国省级审计机关的审计活动不仅会降低本地贫困人口规模,在不同省份之间也存在显著的外溢效应。因此,审计机关应进一步完善区域性协同机制,积极建设跨区域协作平台,充分发挥国家审计空间溢出效应,实现扶贫审计动态全覆盖,保障和改善民生。     

纳米SiO_(2-λ)抗老化性研究及其应用

利用纳米SiO_(2-x)的光学反射性能,添加到涂料、颜料及防晒化妆品等领域,能大幅提高材料的抗老化程度及其它技术指标,具有极大的应用开发前景。     

中国区块链技术在产品追溯领域的应用研究图景——基于 CiteSpace 知识图谱分析

近年来,区块链技术在产品追溯领域的应用研究逐渐成为一个热点论域而广受关注.运用文献计量和知识图谱的方法,聚焦区块链研究迅猛发展的2016—2020年,对区块链技术在产品追溯领域的应用研究进行定量和定性的全面思考,提出区块链国家战略下,应以增强核心研究力量以激发学术共同体的研究使命为基础,以基础与应用研究相结合不断调整研究重心,充分拓展多元应用场景,从而深入推动区块链技术在产品追溯领域的研究路向.     

Extrapolation of causal effects – hopes,assumptions, and the extrapolator’s circle

ABSTRACT

I consider recent strategies proposed by econometricians for extrapolating causal effects from experimental to target populations. I argue that these strategies fall prey to the extrapolator’s circle: they require so much knowledge about the target population that the causal effects to be extrapolated can be identified from information about the target alone. I then consider comparative process tracing (CPT) as a potential remedy. Although specifically designed to evade the extrapolator’s circle, I argue that CPT is unlikely to facilitate extrapolation in typical econometrics and evidence-based policy applications. To argue this, I offer a distinction between two kinds of extrapolation, attributive and predictive, the latter being prevalent in econometrics and evidence-based policy. I argue that CPT is not helpful for predictive extrapolation when using the kinds of evidence that econometricians and evidence-based policy researchers prefer. I suggest that econometricians may need to consider qualitative evidence to overcome this problem.     

医院废水的管理与膜处理技术

介绍了发达国家对医院废水排放的严格要求和控制方法,讨论了我国医院废水处理的现状与存在的问题,并介绍了一种以膜—生物反应器为核心结合紫外线消毒技术形成的医院废水处理新技术。     

红外碳硫仪测定土壤中碳含量的探讨

目前,传统土壤中碳的测定常采用重量法、容量法、气量法等手段,这些方法存在装置复杂、操作繁琐、效率低下、不易掌握等诸多问题,不能满足大批量地质土壤样品的分析。本文探讨通过采用高频红外碳硫分析仪代替传统手段对土壤中碳、有机碳和无机碳进行测定的可行性及优越性,并分析测定过程中进一步提高测定准确度、提升操作效率、提升实验室经济效益的方法手段。     

Investments in tracking and tracing systems in the food industry: A PLS analysis

Traceability and related concepts, such as trust and transparency have gained greatly in relevance in food supply chains. This study seeks to answer what exactly determines firms’ investments in traceability systems by developing and testing a theoretical framework using partial least squares methodology and empirical data from 234 companies of the German food industry.The results reveal that high external pressure to implement improves the image of tracking and tracing systems in the sense that their use enhances a firm’s status, increases the intention to use those systems and fosters their perceived usefulness in the eyes of agribusiness executives. The hypothesized negative effect of costs on perceived usefulness and the intention to invest could not be verified.