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.     

影响漏电起痕试验结果的因素分析

针对绝缘材料漏电起痕试验中存在的影响正确试验结果的问题,例如试样选取、试样预处理、溶液配置、实验设备清洗及安装等方面,本文根据GB/T 4207-2003和IEC60112-2003标准的要求,通过对标准的理解和经验的总结,提出了影响漏电起痕实验结果的各种因素及相应的处理方法,在一定程度上能够减少试验误差,提高试验准确性,有助于相关检测部门改进试验方法。     

Rebuilding the limit order book: sequential Bayesian inference on hidden states

The limit order book of an exchange represents an information store of market participants’ future aims and for many traders the information held in this store is of interest. However, information loss occurs between orders being entered into the exchange and limit order book data being sent out. We present an online algorithm which carries out Bayesian inference to replace information lost at the level of the exchange server and apply our proof of concept algorithm to real historical data from some of the world’s most liquid futures contracts as traded on CME GLOBEX, EUREX and NYSE Liffe exchanges.     

信道群时延特性的工程测量

信道的群时延指标对跟踪系统的测量精度和通信系统的信号质量都十分重要。但该项指标的测试通常因缺乏专用仪器而不能进行,影响了设备误差的分析和系统潜力的发挥。本文介绍利用常用的仪器,采用调制法进行群时延测量的构想,并着重解决了调制器引入的群时延漂移。论述了测量的合理性和调制频率选择的依据,对测量结果进行了分析。     

Optimizing tracking error-constrained portfolios

Active portfolios subject to tracking error (TE) constraints are the typical setup for active managers tasked with outperforming a benchmark. The risk and return relationship of such constrained portfolios is described by an ellipse in traditional mean-variance space and the ellipse’s flat shape suggests an additional constraint which improves the performance of the active portfolio. Although subsequent work isolated and explored different portfolios subject to these constraints, absolute portfolio risk has been consistently ignored. A different restriction – maximization of the traditional Sharpe ratio on the constant TE frontier in absolute risk/return space – is added here to the existing constraint set, and a method to generate this portfolio is explained. The resultant portfolio has a lower volatility and higher return than the benchmark, it satisfies the TE constraint and the ratio of excess absolute return to risk is maximized (i.e. maximum Sharpe ratio in absolute space).     

提高战术通信电子抗干扰能力的可能途径

本文从直接序列（ＤＳ）和跳频（ＦＨ）处理增益的讨论出发,引用有关文献的分析结果,对ＤＳ、ＦＨ、ＤＳ／ＦＨ在常见干扰形式下的优劣作了比较。针对跟踪式干扰工作机制,提出增强ＦＨ,ＤＳ／ＦＨ对抗跟踪式干扰的间接方法。     

无线电测控系统中三元码跟踪双环的研究

本文提出了数字遥测信号与模拟图象信与混合的无线电测控系统中用于捕获和跟踪带钟复合码的跟踪双环方案,分析了双环系统的捕获性能,理论分析和实验结果表明,双环系统不仅捕获时间短,而且具有强的抗干扰能力。     

基于GVT的公园游憩偏好分析及管理 对策——以上海世纪公园为例

城市综合公园是城市人居生态的重要组成部分。处理 好城市公园与居民的关系,在满足公园服务功能的同时保障公 园自身的良性环境,是当今城市公园建设的重要课题。以上海 世纪公园为研究对象,基于游客轨迹数据和补充问卷调研分析 了游客游憩偏好。结果显示,受景观资源不均衡分布的影响, 游览路径表现出主路聚集、区域分散的现象;停留空间与游客 需求相关,其中老年、中青年和家庭3类典型游客的主要停留 节点分别是休憩服务设施、公园植物景点和游乐活动场所。针 对环湖区域游客集中的问题,从亲水因素的角度开展分析,发 现景观和设施资源分配的不均导致游客对空间亲水性的依赖差 异。结合游客群体的游憩偏好特征,重点针对老年和中青年游 客提出了公园管理和场地更新建议,助力解决临水区域游客压 力过大的问题。     

Cruise passengers' behavior at the destination: Investigation using GPS technology

This paper aims at segmenting cruise passengers in order to identify passengers' profiles according to their behavior at destination. Through an integrated use of traditional survey instruments and of GPS technologies, a set of indicators for the analysis of passengers' mobility at destination is proposed. Data collected in the port of Palermo are used in order to investigate space-time activities of cruise passengers at the destination. Monothetic Analysis is used in order to segment passengers according to their behavior at destination, and groups are then compared in terms of socio-demographic characteristics and other variables collected through questionnaire-based survey. Results identify seven different broad patterns of activity, and indicate that several socio-demographic characteristics and other features of passengers seem to be associated with movement patterns at destination. A better knowledge of cruise passengers' behavior at destination is a fundamental pre-requisite in order to better serve visitors' needs and meet their expectations.     

数字化角跟踪接收机的设计与实现

介绍了数字化跟踪接收机方案设计，以及应用FPGA和DSP等数字处理器件提取角跟踪误差信号的方法。