一种针对压缩域信号的新型锁相环技术

针对通信信号压缩采样获得的压缩域信号频率、相位提取问题,提出了一种基于压缩感知的新型锁相环技术。通过深入研究压缩域的信号估计问题,提出了压缩域锁相环路,可以直接在压缩域同步跟踪信号频率和相位变化,不再需要高复杂度的信号重构处理。分析了环路模型及其估计性能,并针对该锁相环可行性和性能分别进行了仿真实验。仿真结果不仅验证了压缩域锁相环的可行性,同时表明该环路能够实现高动态信号的高精度频率提取。压缩域锁相环的应用潜力较大,例如可以作为压缩感知通信接收机的同步解调方法。     

黑土典型区有机质高光谱预测模型

土壤有机质(SOM)是鉴别土壤肥力的重要指标,是土壤肥力的物质基础,其含量预测模型研究对于土壤肥力评价、土壤碳库估算、土壤资源利用与保护具有重要意义。该文以黑龙江省黑土带典型区为例,采集区域土壤样本,基于有机质含量与土壤反射率的定量关系,对光谱反射率进行一阶微分和倒对数的处理,建立偏最小二乘法模型(PLSR)、一元线性回归模型和多元线性逐步回归模型。结果表明:(1)土壤有机质敏感波段位于650-750nm。(2)通过比较建模样本与检验样本的决定系数(R2)和均方根误差(RMSE)的大小,得到反射率和倒对数处理后的数据最优模型都为PLSR模型,一阶微分处理后的最优模型为多元线性逐步回归模型。(3)PLSR模型的建模效果优于回归模型,但其预测效果却并不理想。该研究将为改进土壤理化参数、遥感反演、土地质量评价等工作方法提供理论与技术支持。     

基于“北斗一代”的Zigbee无线网关设计

为了解决野外多点数据采集无供电、布线复杂和通信困难的问题,提出了一种基于“北 斗一代”的Zigbee无线网关设计方案。采用MSP430F6438、CC2341微处理器和一体化的RDSS “北斗”射频芯片完成低功耗、小成本的硬件设计。通过增加SIM卡的数量,将网关转发“ 北斗”数据的频率降至最低的5 s,提高了网关的通信速率。通过软件设计实现了Zigbee无 线传感网络和“北斗一代”系统之间数据的透明交换。该方法已成功应用于野外油气井远程 监控系统中。     

一种无人值守接力的靶场安控系统

本文论述了中国实行对外开放是邓小平和中国人民把握历史和时代发展规律作出的战略抉择并取得了巨大成就;分析总结了中国入世前对外开放的基本特征及其原因;重点探讨了中国入世后对外开放的新阶段、新特点及其应对措施,推动对外开放新阶段和开放型经济新发展。     

Flexible Working,Individual Performance,and Employee Attitudes: Comparing Formal and Informal Arrangements

In the context of a wider trend to individualize human resource management, this article examines the relationship between flexible working arrangements and individual performance. Drawing on a range of theories, this article also examines potential indirect effects on employee performance via job satisfaction and organizational commitment and analyzes whether these relationships vary according to whether the arrangement was set up through a formal process or negotiated informally between the employee and his or her line manager. Extant research has tended to focus on formal arrangements, however, informal arrangements are widespread and may better accommodate work‐life preferences, thereby potentially fostering more positive attitudes from employees. Survey data from 2,617 employees in four large organizations with well‐established flexible working policies are analyzed. Results from structural equation models show average positive indirect effects from informal flexible working, but also negative direct effects from formal flexible working. When two forms of flexible working amenable to being set up by both formal and informal means are examined separately, formal arrangements for flexibility over working hours are found to be negatively associated with performance, but also a source of greater job satisfaction; informal remote working arrangements have positive indirect effects via organizational commitment and job satisfaction on worker performance. © 2016 Wiley Periodicals, Inc.     

Implications of land use transitions on soil nitrogen in dynamic landscapes in Tanzania

Land use transitions are rated among the leading sources of greenhouse gas emissions in the tropics. They significantly challenge the functioning of ecosystems and affect multi-temporal stability of greenhouse gases such as N₂O and soil properties. Studies on dynamics in nitrogen balances are essential in understanding greenhouse gas emissions such as N₂O and to manage their impacts on productivity. In this study, multi-temporal Landsat images (1975, 1995 and 2012) were classified to determine land use transitions and potential drivers. The classified images were categorized into degraded and non-degraded lands and eighty sampling plots generated within the entire study area. Soil samples were then collected at 0–15, 15–30 and 30–60 cm depths on each plot and soil nitrogen determined. A regression analysis was developed to determine the influence of forest and grassland degradation on soil nitrogen. Results indicated a significant change in major land use and land cover types. Specifically, there was a decrease in areas covered by forests, woodland and grassland, however, area covered by less dense forest increased. Results also indicated variability in mean nitrogen content between degraded and non-degraded areas and depths. Furthermore, levels of degradation influence nitrogen content up to a soil depth of 30 cm. The present study is relevant in the detailed assessment of the extent of damage and threats posed to biodiversity hotspots in sub-Saharan Africa. These results are transferable to other parts of the world characterized by dynamic ecological transformation.     

远程自动抄表系统在取水计量实时监控中的应用

当前,我国经济正处于快速增长期,用水量大幅度增长,水资源供需矛盾突出。文章以广西来宾市远程自动抄表系统在取水计量实时监控中的应用为例,从战略上分析了做好节水工作的重要性。     

Disclosure‐protected Inference Using Generalised Linear Models

Vast amounts of data that could be used in the development and evaluation of policy for the benefit of society are collected by statistical agencies. It is therefore no surprise that there is very strong demand from analysts, within business, government, universities and other organisations, to access such data. When allowing access to micro‐data, a statistical agency is obliged, often legally, to ensure that it is unlikely to result in the disclosure of information about a particular person or organisation. Managing the risk of disclosure is referred to as statistical disclosure control (SDC). This paper describes an approach to SDC for output from analysis using generalised linear models, including estimates of regression parameters and their variances, diagnostic statistics and plots. The Australian Bureau of Statistics has implemented the approach in a remote analysis system, which returns analysis output from remotely submitted queries. A framework for measuring disclosure risk associated with a remote server is proposed. The disclosure risk and utility of approach are measured in two real‐life case studies and in simulation.     

松嫩平原生态资产遥感测量与生态分区研究

生态资产测量与价值评估以生态系统服务功能效益和自然资源价值为核心,直接反映了生态环境发展变化的状态和结果,进行区域生态资产核算,对于国民经济发展和生态环境保护具有重要意义.本文应用生态学、经济学和生态环境科学等学科的理论,以TM和MODIS卫星遥感影像、气象数据和DEM数据为数据源,在进行松嫩平原腹地土地利用变化遥感解译和生态环境要素定量反演的基础上,建立了区域生态资产遥感测量的概念模型和指标体系,进而进行了松嫩平原生态资产的定量测算与分区对比研究.结果表明,松嫩平原腹地2002年总生态资产价值为659.681 8亿元,平均生态资产价值林地最高,达到18 432.16元/hm2,其次为湿地和高覆盖草地,盐碱地最低,仅为1 447.66元/hm2.在空间分布上,松嫩平原腹地北部的生态资产值明显高于南部,呈现出沿东北向西南逐渐下降的趋势.     

城市遥感在数字城市中的应用

随着城市化和信息化的稳步推进,数字城市建设被各地纳上议程。城市遥感在海量数据获取和处理方面具有强大优势,因而成为数字城市建设的核心技术之一。本文就城市遥感在数字城市建设中的具体应用进行了详细阐述。