Leaf‐Nets (LN): A New Quantitative Method for Sampling Macroinvertebrates in Non‐Wadeable Streams and Rivers

The ecological knowledge of large rivers is still scarce or highly fragmented mainly because of complex, laborious and expensive procedures to collect informative samples from the benthic biota. Standard sampling protocols for macroinvertebrates were mainly developed and calibrated for wadeable streams, while a number of heterogeneous non‐standard sampling procedures are available for large rivers. We propose the new, easy‐to‐build and cost‐effective leaf‐nets (LN) method to quantitatively sample benthic invertebrates in non‐wadeable waterways. The LN method uses Phragmites australis leaves as substrate and combines the characteristics of the leaf‐bags and the Hester–Dendy (HD) multiplates methods. We compared the effectiveness of the LN and HD methods in a near‐pristine and in an impacted stream‐reach (downstream an aquaculture plant) of a non‐wadeable second‐order stream of Central Apennines (Italy). Twenty‐five of the 34 cumulatively collected macroinvertebrate taxa were common to both methods, while seven taxa were found only on LN and two only on HD. Taxonomic richness and total macroinvertebrate abundance were higher for LN assemblages. Number of Ephemeroptera, Plecoptera and Trichoptera taxa (EPT) also tended to be higher on LN. Assemblage composition was different on LN and HD. Both methods documented a significant decrease in EPT taxa and a concomitant increase in the total abundance of more pollution‐tolerant taxa in the impacted stream‐reach, but the LN method was more sensitive to impact‐associated changes in macroinvertebrate assemblage structure. In contrast to the hardboard plates of HD, the assembled leaves of the LN may act as a direct or indirect food source and may better mimic the texture and composition of more heterogeneous natural substrates thus favouring the migration–colonization process from both bottom and littoral benthic invertebrates. The sampling efficiency, cost effectiveness and simplicity warrant the routine use of the new LN method in large‐river ecological assessment. Copyright © 2015 John Wiley & Sons, Ltd.     

基于资源权重最大资源利用率的动态资源调度算法

对于在云环境下虚拟机放置问题,资源调度管理是其中一项关键技术,因而提出了一种基于最大综合利用率为标准的动态资源调度算法。首先,在云系统调度中心缓存用户的资源请求,将此请求当做一个任务,然后利用负载均衡调度算法,调度中心针对不同任务来分配适当的物理机,最后在物理机上建立虚拟等待队列,充分考虑云系统中计算资源权重比,利用基于权重最大资源利用率的算法进行虚拟机配置。仿真实验结果证明,该算法可以实现有效负载均衡,并在保证一定的QoS的情况下,能有效提高系统的综合利用率。     

An integrated inventory model with capacity constraint and order-size dependent trade credit

Trade credit has many forms in today’s business practice. The most common form of trade credit policy that is used to encourage retailers to buy larger quantities is order-size dependent. When the number of ordered units exceeds the capacity of the own warehouse, an additional rented warehouse is required to store the excess units. Therefore, to incorporate the concept of order-size dependent trade credit and limited storage capacity, we proposed an integrated inventory model with capacity constraint and a permissible delay payment period that is order-size dependent. In addition, the unit production cost, which is a function of the production rate, is considered. Three theorems and an algorithm are developed to determine the optimal production and replenishment policies for both the supplier and the retailer. Finally, numerical examples are presented to illustrate the solution procedure and the sensitivity analyses of some key parameters are provided to demonstrate the proposed model.     

异构多核系统中跨时钟域的解决方法

随着集成电路的集成度与性能的不断发展,芯片的功耗问题已经变的十分严重,功耗带来的挑战日益突出。异构多核动态调频架构是目前研究低功耗的主流方向。SOC系统当中同一时刻只有一个处理器能够控制总线,其它处理器则处理等待状态,异构多核动态调频架构能够通过降低不控制总线的处理器频率来达到降低功耗的目的。异构多核领域的处理器和总线跨时钟域解决方案,此方案在国内属于首次提出,可以运用在异构多核动态调频(DFS)架构当中。目前手持终端设备越来越强调功耗的重要性,因此异构多核领域的处理器和总线跨时钟域解决方案将有非常好的应用前景。该方案通过在处理器和AMBA总线之间添加FIFO以及一些复杂的算法,达到消除亚稳态和正常通信的目的。最终,通过仿真发现任意调节处理器的工作频率都能满足传输协议。证明该方案能在异构多核动态调频架构中运用。     

微小型组合导航系统软硬件协同设计

针对机载制导武器对组合导航系统小体积、低功耗、高实时性以及高可靠性的要求,设计了组合导航系统双CPU总体方案。基于Zynq全可定制平台搭建了组合导航系统硬件环境。在分析组合导航系统软件结构的基础上,对任务块、任务优先级以及任务间的同步机制进行了合理设计;同时基于对组合导航滤波器内数据交换的分析,通过设置消息队列实现了任务间通信,且在保证数据一致性的同时,避免了“死锁”问题的出现。     

基于CAN总线的底盘综合控制系统设计

设计了基于CAN总线的底盘综合控制系统,主要包括对整车、四轮驱动、转向系统和制动系统的控制器设计。采用CAN总线实现电动汽车各控制器间的通信,并完成了CAN网络应用层协议的制订。在综合考虑相关影响因素基础上,设计了各控制器的硬件,建立伪逆控制分配算法实现常规的控制量分配,以及必要时实现控制再分配,保证车辆的操纵稳定性。系统的仿真结果表明,该系统可有效地完成常规和再分配控制量,兼顾电动汽车的灵活与稳定。     

飞行器综合测试设备可靠安全接地设计

飞行器综合测试主要对电气系统各功能及接口的协调性和匹配性进行全面的综合检查。测试设备接地不正确,可能干扰地面设备和飞行器产品,甚至将危险电压引到飞行器上。本文简要介绍接地的作用,结合飞行器综合测试系统功能和组成,分析了各类测试设备的接地原则和方法,最后提出测试设备接地安全保证措施,为航天项目产品研制提供参考。     

吉音水利枢纽智能一体化管控系统的研究

介绍吉音水利枢纽智能一体化管控系统的总体设计方案及水电厂监控、水情水调、大坝监测、生产信息、工业电视、网络通信等子系统,从设计思路、总体架构、分层分区等方面进行详细阐述,对多专业融合的综合管控系统进行探索研究,同时简述项目的实施及系统的运行情况,对水利工程管理单位信息化系统的方案设计具有一定的参考作用。研究表明,一体化管控系统非常适合综合型水利信息化工程。