基于星上自适应FEC的卫星数据分发

为了解决卫星数据分发系统中雨衰对下行链路的异构性影响,建立了基于再生转发器和多波束技术的卫星数据分发系统简化模型,提出了采用星上自适应分组级FEC（Forward Error Control）的下行链路差错控制方法,针对下行链路的降雨等级自适应选择纠错码率,在不占用上行共享链路的情况下,实现对下行链路差错控制的动态调整,给出了采用RSE码的星上自适应FEC的算法公式,通过MATLAB软件和端到端的FEC技术进行了仿真比较分析,结果表明,当下行链路降雨率小于50%时,网络吞吐率可提高12%~25%。该策略可以为多波束宽带卫星数据分发系统的设计提供参考。     

双向多中继协同通信系统的性能分析

针对频率非选择性瑞利衰落信道,研究了双向多中继协同通信模型的系统性能。首先,基于模型的信号传输过程分析了系统的信道容量;然后,根据接收信噪比的累积分布函数推导了系统中断概率的闭合上界表达式;进一步在MPSK调制方式下,通过计算在高信噪比条件下的矩母函数,推导了平均误码率的闭合表达式。仿真结果验证了理论推导的正确性,并且表明双向多中继模型的中断概率和平均误码率两项性能指标都优于双向单中继模型。     

清至民国时期黔东南苗侗族民众之田土山林诉后防御策略

清至民国时期,黔东南苗侗族民众在田土山林诉讼之后有独具特色的防御策略,即将官府判词刊刻在石碑上,立于桥头路口等众人途经之处,以警示他人以后对判决所涉田土山林不得再生觊觎之心。黔东南苗侗族民众之所以采取这种诉后防御策略,其主要有以下几个方面的原因:一是田土山林对黔东南传统苗侗族民众来说意义非常重大;二是意图减少或者避免以后的讼累;三是官府判决的权威性已经在黔东南得到显现。黔东南苗侗族民众的田土山林诉后防御策略对法制建设的启示:要加强对民众田土山林权益的保护,减轻民众的诉讼负担。     

Measuring agricultural knowledge and adoption

Understanding the tradeoffs in improving the precision of agricultural measures through survey design is crucial. Yet, standard indicators used to determine program effectiveness may be flawed, and at a differential rate for men and women. We use a household survey from Mozambique to estimate the measurement error from male and female self‐reports of their adoption and knowledge of three practices: intercropping, mulching, and strip tillage. Despite clear differences in human and physical capital, there are no obvious differences in the knowledge, adoption, and error in self‐reporting between men and women. Having received training unanimously lowers knowledge misreports and increases adoption misreports. Other determinants of reporting error differ by gender. Misreporting is positively associated with a greater number of plots for men. Recall decay on measures of knowledge appears prominent among men but not women. Findings from regression and cost‐effectiveness analyses always favor the collection of objective measures of knowledge. Given the lowest rate of accuracy for adoption was around 80%, costlier objective adoption measures are recommended for a subsample in regions with heterogeneous farm sizes.     

管理层权力对企业绩效的影响研究——基于企业内部治理机制视角

以我国主板上市企业数据为基础,实证检验了上市企业管理层权力对企业绩效的影响,内部治理机制对管理层权力——企业绩效敏感性的影响。实证结果表明,内部治理机制影响管理层权力与企业绩效之间关系的敏感性,当不考虑内部治理机制时,企业绩效与管理层权力综合变量在1%水平上显著正相关,具有较高教育背景和持有企业股权的管理层,能为企业带来更好的业绩。当考虑内部治理机制时,企业绩效与管理层权力综合变量仅在10%水平上正相关。管理层权力综合变量对股权制衡度较低和独立董事比重较高的企业的绩效具有显著正向影响。     

Controlling the commercialisation of science across inter-organisational borders: Four cases from two major Swedish universities

The purpose of this paper is to analyse how different types of controls are applied in different mechanisms for commercialising science, depending on the inter-organisational interactions involved. To achieve this purpose, we followed a multiple-case study design and selected four cases from Uppsala University and the Karolinska Institutet that provided variation in the commercialisation mechanisms (PET Centre, Ångström Materials Academy, Actar, and Karolinska Development). We find that action and result controls dominate in linear ‘spin-out’ funnel mechanisms, while interactive mechanisms entail a combination of action, result and personal controls. However, the inter-organisational interactions also impact which controls are applied in a commercialisation mechanism: conflicting goals between a few closely related organisations or limited external interactions are associated with result controls, while action controls dominate in the absence of external interactions if time and efficiency are key goals. Result controls also assume very different roles, depending on the inter-organisational context of a specific commercialisation mechanism.     

降低大口径容积式流量计计量误差的探讨

国内原油长输管道交接计量大多采用大口径容积式流量计。尽管容积式流量计误差可控制在±0.2%以内,但受制造工艺和使用条件,以及流量计检定工况与交接工况的差异、油品物性参数变化等因素的影响,流量计的计量误差有时较大。以交接计量油量计算实例,探讨采用流量计系数修正的方法,降低容积式流量计的计量误差。     

一氧化碳检测报警器示值误差测量结果的不确定度评定

运用一氧化碳检测报警器,结合长庆油田的实际,利用测量不确定度评定的知识,通过建立数学模型、分析各输入量的标准不确定度、合成标准不确定度及扩展不确定度,给出测量不确定度报告,以达到对一氧化碳检测报警器示值误差测量结果的不确定度评定的目的。     

Time Series Analysis of Repeated Surveys: The State–space Approach

Cross sectional estimates from repeated surveys form a time series { y_t }. These estimates can be viewed as the sum y _t = Y _t + e _t of two processes, { Y _t }, the population process and { e _t }, the survey error process. Serial correlations in the latter series are usually present, mainly due to sample overlap. Other sources of data such as censuses, administrative records and demographic population counts are also available. The state–space modelling approach to the analysis of repeated surveys allows combining information from different sources, incorporating benchmarking constraints in a natural way. Results from these methods seem to compare favourably with those from X-11-ARIMA in filtering out survey errors.     

An alternative definition of individual bioequivalence

Several definitions of individual bioequivalence of two formulations of a medical treatment (drug) have been proposed recently. These definitions attempt to adapt the criterion of average bioequivalence, which would be deficient if substantive treatment heterogeneity were present. In some of the proposed definitions, relatively large differences of means can be compensated by differences in the measurement-error variances. We propose a definition based on a simple latent-variable model which overcomes this anomaly and need not involve the U.S. Food and Drug Administration's 80/125 rule. Our approach is based on a moment-matching estimator of the discrepancy between the outcomes underlying the subjects' responses. The distribution of this estimator is a linear combination of independent χ² variates; asymptotically, it can be approximated by a normal distribution. Evidence of individual bioequivalence corresponds to rejecting the hypothesis that the discrepancy is greater than a specified threshold. The approach is illustrated by reanalysing two bioequivalence trials.