基于节点双向选择的水声传感网络自适应能量优化分配

针对水下传感器网络节点能量负载不均衡以及水下节点路径传输损耗过大等问题,为了平衡网络的节点能量分配,提高网络能量的利用效率,提出了一种基于节点双向选择的水声网络自适应能量优化分配算法。基于节点的剩余能量情况提出下一跳候选节点的双向选择方法,防止剩余能量过低的节点在传送数据时由于传输损耗过大而中止,充分考虑节点剩余能量和传输损耗之间的权衡,提出了最优转发节点的竞争公式,再通过比较候选节点的竞争值来选举最佳的下一跳节点。实验仿真表明,自适应能量优化分配算法能够有效地提高水下传感器网络的能量利用效率,并通过与对比算法组的比较证明了算法在能量优化上的有效性。     

浅谈校园网网络性能评估

本文介绍了校园网网络性能评估背景和网络性能指标,针对网络性能指标提出了网络性能评估的技术与方法,并且介绍了如何选择评估工具,为校园网网络性能评估提供了理论依据。     

A modified dynamic surface approach for control of nonlinear systems with unknown input dead zone

This paper focuses on the robust output precise tracking control problem of uncertain nonlinear systems in pure‐feedback form with unknown input dead zone. By designing an extended state observer, the states unmeasurable problem in traditional feedback control is solved, and the lumped uncertainty, which is caused by system unknown functions and input dead zone, is estimated. In order to apply separation principle, finite‐time extended state observer is designed to obtain system states and estimate the lumped uncertainty. Then, by introducing tracking differentiator, a modified dynamic surface control approach is developed to eliminate the ‘explosion of complexity’ problem and guarantee the tracking performance of system output. Because tracking differentiator is a fast precise signal filter, the closed‐loop control performance is significantly improved when it is used in dynamic surface control instead of first‐order filters. The L _∞ stability of the whole closed‐loop system, which guarantees both the transient and steady‐state performance, is shown by the Lyapunov method and initialization technique. Numerical and experiment examples are performed to illustrate our proposed control scheme with satisfactory results. Copyright © 2013 John Wiley & Sons, Ltd.     

Effect of Ce(3+) on soluble microbial products production in anaerobic granular sludge digestion

Upflow anaerobic sludge bed reactors fed on glucose were used to investigate the effects of Ce(3+) on soluble microbial products (SMP) production, which is the majority of the residual chemical oxygen demand present in the effluent. It was found that Ce(3+) concentration of 0.05 mg/L had no significant effect on the amount of SMP production, whereas that of 1 mg/L led to the increase in SMP production. The molecular-weight distribution and carbohydrate analysis indicated that an increase in SMP production may be partly attributed to the release of extracellular polymeric substances (EPS) into the bulk solution resulted from cerium toxicity, and the nucleic acids analysis suggested that increased cell lysis also contributed to SMP accumulation in the presence of Ce(3+). The increase in SMP production in the presence of Ce(3+) is possibly a consequence of the release of EPS and increased cell lysis due to cerium toxicity.     

Singular Spectrum Analysis and ARIMA Hybrid Model for Annual Runoff Forecasting

High accuracy forecasting of medium and long-term hydrological runoff is beneficial to reservoir operation and management. A hybrid model is proposed for medium and long-term hydrological forecasting in this paper. The hybrid model consists of two methods, Singular Spectrum Analysis (SSA) and Auto Regressive Integrated Moving Average (ARIMA). In this model, the time series of annual runoff are first decomposed into several sub-series corresponding to some tendentious and periodic motions by using SSA and then each sub-series is predicted, respectively, through an appropriate ARIMA model, and lastly a correction procedure is conducted for the sum of the prediction results to ensure the superposed residual to be a pure random series. The annual runoff data of two reservoirs in China are analyzed as case studies. The results have been compared with the predictions made by ARIMA and Singular Spectrum Analysis-Linear Recurrent Formulae (SSA-LRF). It is shown that hybrid model has the best performance.     

天津市居住小区排水管噪声主观评价调查

通过对三个不同居住小区住户的入户访谈及问卷调查,了解排水管的使用性能及产生的噪声对住户的影响情况,探索合理的排水系统设计方案.要满足现代住宅对卫生间排水管敷设方式的基本要求,卫生间、厨房采用同层排水方式无疑是一种解决问题的好办法.     

天津市于桥水库饮用水源地保护对策研究

于桥水库作为天津市最重要的饮用水水源地,其库区水体氮、磷浓度接近国家标准阈值,亟需采取保护防治措施缓解水体氮、磷污染负荷压力。本文基于水库型饮用水水源地环境保护技术框架的一般思路,开展了对于桥水库水环境治理技术方案的分析研究。首先,使用GWLF(普适流域负荷函数)模型对水库周边流域污染源负荷进行识别与负荷解析;之后,基于最佳管理实践(BMP)和低影响开发(LID)的理念和方法,同时根据于桥水库的具体实际情况,提出相应的工程治理措施,并采用BATHTUB模型对各工程措施进行环境效益评估计算;最后使用模糊层次分析法(FAHP)对各工程措施进行择优分析,得出最佳治理实施方案。     

基于RBAC权限管理模型在OA系统中的运用

分析了传统的RBAC权限管理模型,并根据国内企业的需求和特点,在RBAC的基础上设计了更灵活的权限管理机制,很好的满足了企业的需求。     

基于规则的土壤数据校验模型研究与实现①

数据校验是数据挖掘与知识发现中的重要一环。我国土壤观测数据由于台站观测人员上网条件、观测地记录不便以及需要适当的数据预处理等原因,无法实行在线入库,一般借助于Excel等软件来记录中间结果,再提交土壤分中心,这样的记录过程经常引入不必要的错误。提出了一个基于可定制规则库的土壤数据校验模型。模型主要包括数据格式转换模块、权限管理模块、元数据管理模块、重复记录去除模块、数据校验模块及规则定制与解析模块。低侵入式的轻量级设计,使得在大大减轻数据校验人员工作量的情况下,原有的数据填报流程不需要改变。可定制规则使得模型易于扩展。