Block scheduled versus traditional biology teaching—an educational experiment using the water lily

In this study, we compared a traditional teaching sequence (four distinct lessons) with a block schedule dealing with the ecological adaptations of the water lily. The educational unit contained original plant material and both experimental groups received the same tasks and working sheets. Pupils worked together in groups of three to four pupils in a self-regulated manner, carrying out hands-on experiments. However, both groups differed in their time schedule (four distinct lessons of 45 min versus one block of 180 min). Pupils from the traditionally scheduled education performed significantly better in the immediate post-test while these differences merged in retention.     

耦合故障下增程器不对中故障诊断特征变化研究

在增程器失火-不对中耦合故障下,通过多工况下虚拟样机仿真,对不对中故障的故障诊断特征的变化规律展开了研究。借助虚拟样机平台搭建了某款增程器虚拟样机刚柔混合模型;对已经探索得到的不对中故障诊断特征,在多转速、多失火状态工况下,研究耦合故障下不对中故障特征变化规律;对耦合故障下的增程器转子系统进行动力学分析,结合机理研究,对不对中故障诊断特征的变化进行了原理分析;由此得到耦合故障工况下不对中故障诊断特征变化规律。     

Scheduling algorithm for multimedia services in IEEE 802.16e OFDM system

Based on five scheduling types and their QoS requirements defined in IEEE 802.16e specification, this paper proposes a new scheduring algorithm for non-real-time or real-time multimedia services. Taking the performances of efficiency, fairness and complexity into consideration, the proposed algorithm enhances the efficiency of air interface resource at the expense of the short-time unfairness, but ensures the long-time fairness. Moreover, the proposed algorithm introduces an efficient QoS assurance mechanism, which implements the functions of congestion control, queuing management and traffic management. The simulation results based on a simplified traffic model show that the proposed algorithm guarantees better performances of efficiency and fairness than conventional algorithms, without increasing the algorithm complexity. Especially on the occasion of heavy-traffic requirement, the performance of efficiency and fairness can be improved by 50% at most.     

变推力作用下的柔性旋转飞行器动力学建模

The dynamic response of a flexible spinning vehicle with the varying thrust was investigated. The varying thrustwas modeled as a series of simple harmonic components superimposed on a constant thrust. The analytical solutions forlongitudinal motion were obtained by combining the motion equations and boundary conditions, and then, the transversebending of rocket was examined solved by considering a coupled forcing vibration with varying parameters. Numericalsolutions for a rocket with end-varying thrust were studied. It is shown that the lateral vibrations and motion attitudes ofrocket depend on the frequencies of varying thrust to great extent, and an important phenomenon, beating, maybe take place.The proposed approach is more accurate and efficient in comparison to those standard numerical techniques.     

工件加工时间退化且可拒的带优势关系流水作业问题的动态规划算法

The permutation flow shop scheduling problems with deteriorating jobs and rejection on dominant machines were studied. The objectives are to minimize the makespan of scheduled jobs plus the total rejection penalty and the total completion time of scheduled jobs plus the total rejection penalty. For each objective, polynomial time algorithms based on dynamic programming were presented.     

一类基于人工免疫系统与极值优化的混合算法求解流水作业调度问题

The permutation flowshop scheduling problem (PFSP) is one of the most well-known and well-studied production scheduling problems with strong industrial background. This paper presents a new hybrid optimization algorithm which combines the strong global search ability of artificial immune system (AIS) with a strong local search ability of extremal optimization (EO) algorithm. The proposed algorithm is applied to a set of benchmark problems with a makespan criterion. Performance of the algorithm is evaluated. Comparison results indicate that this new method is an effective and competitive approach to the PFSP.     

中德美电动汽车产业创新政策比较

德国和美国是电动汽车产业发展最快且成熟度最高的2个国家,其产业创新政策值得我们学习借鉴。从电动汽车未来发展需要提高性能和降低价格的2个方向出发,围绕创新链构建政策分析框架,按照供给型、需求型和环境型的分类对中国、德国和美国电动汽车产业创新政策进行比较并提出政策建议。     

基于两级的公平调度算法

为了保证对各个端口的不同优先级(PRl)的数据包的公平调度，本文提出了一种相适应的算法解决接口间的公平调度和接口内不同优先级间的公平调度。     

并联混合动力汽车动力源参数设计及模糊控制策略的建模仿真分析

根据汽车道路行驶的数学模型计算并联混合动力汽车驱动电机和发动机的各项参数,设计模糊控制策略控制驱动电机和发动机协调工作,使用Matllab/Simulink软件和Advisor汽车仿真软件联合建模仿真。在建模过程中,将上述计算结果输入Advisor汽车模型中,设置汽车的行驶工况、最高车速、加速时间和爬坡能力4个计算任务,并运行计算任务。仿真结果表明:汽车驱动电机和发动机的参数能匹配汽车整车参数、性能要求,模糊控制策略能在保证汽车整车性能要求的前提下进一步减少燃油消耗和尾气排放物,表明本驱动电机和发动机参数匹配设计方法、模糊控制策略均可行。     

计算机集群技术概述

集群(cluster)技术是一种较新的技术,通过集群技术,可以在付出较低成本的情况下获得在性能、可靠性、灵活性方面的相对较高的收益,其任务调度则是集群系统中的核心技术。本文就集群系统的定义、发展趋势、任务调度等问题进行了简要论述。