光学遥感成像系统全链路仿真框架研究

针对光学遥感成像系统的全链路仿真在我国刚刚起步。通过分析能量在大气、场景和遥感器之间传递时发生的各种相互作用,将整个仿真过程分为三维场景构建与组织、遥感器入瞳处辐亮度图像模拟、遥感器效果模拟三部分,分析了框架中各个模块的功能和模块之间的概念数据流向。最后分析了地形起伏和观测角度变化对成像的影响,计算显示：像元高度从0增至1 km时,入瞳处辐亮度的最大相对差异可达170%;观测天顶角分别从180°变为124.4°时,辐亮度的相对差异最大可接近50%。     

Unsupervised segmentation of hidden semi-Markov non-stationary chains

The Bayesian segmentation using Hidden Markov Chains (HMC) is widely used in various domains such as speech recognition, acoustics, biosciences, climatology, text recognition, automatic translation and image processing. On the one hand, hidden semi-Markov chains (HSMC), which extend HMC, have turned out to be of interest in many situations and have improved HMC-based results. On the other hand, the case of non-stationary data can pose an important problem in real-life situations, especially when the model parameters have to be estimated. The aim of this paper is to consider these two extensions simultaneously: we propose using a particular triplet Markov chain (TMC) to deal with non-stationary hidden semi-Markov chains. In addition, we consider a recent particular HSMC having the same computation complexity as the classical HMC. We propose a related parameter estimation method and the resulting unsupervised Bayesian segmentation is validated through experiments; in particular, a real radar image segmentations are provided.     

高功率因素反激式开关电源的电磁兼容研究

摘要：论文对带有高PF（功率因素）反激式的开关电源的电磁干扰进行了分析。为实现开关电源的EMC（电磁兼容）,在设计过程中采用了EMI滤波器。论文在探讨EMI滤波器的设计原则基础上,分析了高频分布参数对滤波器频率特性的影响,通过设计和调整滤波器的结构及器件参数,实现了EMI传导干扰的有效抑制,使带有高PF反激式的开关电源达到灯具的EMI标准。     

Analysis and Comparison of Location Strategies for Reducing Registration Cost in PCS Networks

In mobile environments, a personal communication service (PCS) network must keep track of the location of each mobile user in order to correctly deliver calls. A basic scheme used in the standard IS-41 and GSM protocols is to always update the location of a mobile user whenever the mobile user moves to a new location. The problem with this approach is that the cost of location update operations is very high especially when the mobile user moves frequently. In recent years, various location management strategies for reducing the location update cost have been proposed. However, the performance issue of these proposed algorithms remains to be investigated. In this paper, we develop two Markov chains to analyze and compare the performance of two promising location update strategies, i.e., the two location algorithm (TLA) and the forwarding and resetting algorithm (FRA). By utilizing the Markov chain, we are able to quickly answer what-if questions regarding the performance of PCS networks under various workload conditions and also identify conditions under which one strategy can perform better than the others. Using the cost due to location update and search operations between two successive calls to a mobile user as a performance measure, we show that when the mobile user exhibits a high degree of locality and the mobile user's call-to-mobility ratio (CMR) is low, TLA can significantly outperform both FRA and IS-41. On the other hand, when CMR is high, FRA is the winner. Furthermore, unlike TLA which may perform worse than IS-41 at high CMR values, FRA at identified optimal conditions can always perform at least as good as IS-41, suggesting that FRA over TLA should be used as a generic scheme in reducing the location cost in the PCS network to cover all possible per-user CMR values.     

Improved Morphology and Efficiency of Polymer Solar Cells by Processing Donor–Acceptor Copolymer Additives

A novel wide‐bandgap conjugated polymer PBTA‐FPh based on benzodithiophene‐alt‐benzo[1,2,3]triazole as the main chain and a polar pentafluorothiophenyl (FPh) group in the side chain has been designed and synthesized. In comparison to the pristine polymer PBTA‐BO that consists of nonpolar alkyl side chains, the resulting PBTA‐FPh exhibits less pronounced aggregation while possessing analogous optical and electrochemical bandgaps. Contact angle measurements demonstrate that the surface energy can be enhanced by incorporating FPh moiety, leading to a better miscibility of PBTA‐BO with PC₇₁BM in the presence of a certain amount of PBTA‐FPh. The photoactive layer of PBTA‐BO:PC₇₁BM:PBTA‐FPh with weight ratio of 1:1.2:0.02% exhibits a percolated network with the fibrous features, as revealed by transmission electron microscopy measurements. Of particular interest is the significantly improved photovoltaic performances of polymer solar cell devices for which the power conversion efficiency is enhanced from 6.46% for the control device to 7.91% for device processed with PBTA‐FPh as the polymeric additive. These observations indicate that introducing donor–acceptor type of polymeric additive comprising of polar groups in the side chain can be a promising strategy for the fabrication of high‐performance polymer solar cells.     

The potential contribution of renewable energy to electricity supply in Saudi Arabia

Saudi Arabia has enormous oil resources. At the same time, the Kingdom has other resources, notably solar energy that may figure in future supplies of electricity. In the past several years, considerable operational experience has been gained throughout the world in the implementation of renewable energy systems of types that would be relevant to the Kingdom. This paper reviews the nature of this experience and applies it in a quantitative assessment of the costs, savings, and environmental benefits of renewable energy conducted as a part of an electric utility integrated resource planning (IRP) project in the Kingdom. Integrated resource planning is an approach that systematically evaluates potential electricity supply and demand-side resources with the aim of developing a plan that provides energy services to customers at the least societal cost. The analysis summarized in this paper has shown that, when some of the non-market benefits of renewable energy are also included in the assessment of their overall costs and benefits, a supply expansion plan that includes wind and solar resources can provide energy services for the Kingdom at a lower societal cost than a “Business-as-usual” plan utilizing only fossil-fueled generating resources.     

供油提前角对柴油/甲醇混合燃料燃烧排放性能的影响

添加助溶剂并使用超声波振动形成混合均匀的柴油/甲醇混合燃料,通过柴油机台架试验,分析供油提前角变化对柴油/甲醇混合燃料燃烧排放的影响。试验结果表明:供油提前角提前,柴油/甲醇混合燃料的有效燃油消耗率降低。随着供油提前角减小,混合燃料滞燃期缩短,供油提前角为21°CA时,混合燃料的燃烧持续期最短,增加或减少供油提前角都将延长燃烧持续期。供油提前角变化对柴油/甲醇混合燃料的排放有较大影响,推迟供油,混合燃料的烟度排放和CO排放增加,NOx排放与HC排放降低。     

The TraceFood Framework – Principles and guidelines for implementing traceability in food value chains

Requirements related to food safety and associated legislation and certification have increased a lot in recent years. Among these are the requirements for systematic recordings to be made throughout the supply chain so that in case of a food crisis it is possible to trace back to source of contamination, and to perform a targeted recall of potentially affected food items. These systematic recordings must be connected to the food items through unique identifiers, and the recordings, the identifiers and the documentation of how ingredients and food items join or split up as they move through the supply chain is what constitutes a traceability system. For the food industry, the traceability system is also an important tool for controlling and optimizing production, for getting better industrial statistics and better decisions, and for profiling desirable product characteristics. Current status is that many food producers have good, often electronic traceability systems internally, but exchange (especially electronic exchange) of information between the links in the supply chain is very time-consuming or difficult due to the diversity and proprietary nature of the respective internal systems. To facilitate electronic interchange of this type of data, an international, non-proprietary standard is needed; one that describes how messages can be constructed, sent and received and also how the data elements in the messages should be identified, measured and interpreted. The TraceFood Framework was designed for this purpose, and it contains recommendations for “Good Traceability Practice”, common principles for unique identification of food items, a common generic standard for electronic exchange of traceability information (TraceCore XML), and sector-specific ontologies where the meaning and the inter-relationship of the data elements is defined. The TraceFood Framework is a joint collaboration of many EU-funded projects dealing with traceability of food products; especially the integrated project TRACE where most of the work related to specification, design and testing of the framework has taken place.     

投标决策模型在供应链计划中的应用

描述了在电子商务环境下,使用竟投标方法制定供应链计划的问题．针对竞标策略中投标价格计算．建立了包括一个随机参数集（产品的将要入库量）和一个模糊参数集（最大销售速率）的供应链计划多智能体合作模型．并使用遗传算法求得问题的近似解．计算结果证明了该算法的有效性和模型的实用性．