“平行志愿”改革七年述评 ——基于政策文本的实证分析

高考制度改革一直为我国社会各界所关注.始于2003年湖南省的"平行志愿"填报与录取方式改革,是我国高考制度中一项重大的改革举措.目前实行平行志愿改革的省市达到16个,有三种不同形式的实施方案.总体而言,改革进一步维护了考生利益、保障了教育公平.然而,"平行志愿"填报录取方式作为一种新生事物,在其实施过程中仍不可避免地存在着一些问题,针对这些问题,作者提出了一些改进措施.     

并联容值公式C=P/wU2(tanФ1-tanФ2)的两种推导法比较

通过对并联电容器容值计算公式C=PwU2(tanΦ1-tanΦ2)的两种推导方法的讨论,证明了在交流电路中,交流量的不同表示方法之间是等效的,而在求解相关问题时,选用不同的表示方法,会对求解问题的复杂程度产生比较明显的影响。     

单板平行大回转滑雪陆地训练器的研制与应用

本研究是设计几种使用单板并可多变角度的单板滑雪平行大回转陆地训练器,克服现有训练方法和器械的不足,利用最新研制开发的模仿器进行力量训练.为提高单板平行大回转滑雪的专项力量、平衡、心肺功能和能力,研制了三种单板平行大回转滑雪陆地训练器,介绍了设计结构、功能和实验,对使用训练方法功效特征进行了分析.目标是训练极限加速运动所需要的肌肉运动系统力量、心肺功能系统能力,可有效提高专项力量水平,促进运动成绩的提高.在实验过程中对器械完成的动作和雪上动作技术相似性和训练效果特征进行了对比分析.     

Application of Corncob-Based Activated Carbon as Electrode Material for Electric Double-Layer Capacitors

To investigate the influence of expansion pretreatment for materials on carbon structure,activated carbons(Acs)were prepared from corncob with/without expansion pretreatment by KOH activation,the struc...     

关于功率因数的讨论

提高用电设备的功率因数,是节约电力能耗的有效手段,讨论了功率因数的含义,阐述了提高功率因数的意义。介绍了提高功率因数的几种方法,从而达到提高电力系统的功率因数、提高设备利用率、节能降耗的目的。     

一种改进的并行关联规则挖掘算法

在FDM算法的基础上,提出了一种改进的并行关联规则挖掘算法FDM_DT,此算法利用DHP算法中的Hash表技术改进了2阶侯选项集的生成过程,并采用Apriori Tid算法中的Tid表技术对事务数据库中的事务数进行有效消减。因此,此算法在处理大规模数据时有较高的综合效率。     

ANSYS在二维静电场分析中的应用研究

利用有限元分析软件ANSYS对形状不规则的二维静电场电场进行求解,其研究结果可以用于分析求解电容器的电场分布,电力电容器分为串联电容器和并联电容器,它们都能改善电力系统的电压质量和提高输电线路的输电能力,是电力系统的重要设备。     

集群Web服务器系统及负载平衡技术在情报信息网中的应用

随着集群的广泛应用, 集群管理的重要性显得越来越明显。分析了负载平衡集群服务器的结构和特点。探讨了基于情报信息网络负载平衡的主要技术。网络负载平衡提高了诸如Web 服务器、FTP 服务器和其它关键任务服务器上的服务程序的可用性和可伸缩性。     

Trajectories of implicit theories and their relations to scholastic aptitude: A mediational role of achievement goals

Implicit theories of intelligence play an important role in students’ academic motivation and achievement. This longitudinal study examined how the trajectories of implicit theories of intelligence from Grade 8 to Grade 10 were related to Grade 12 SAT achievement via Grade 11 achievement goals. We employed parallel process models to examine changing patterns of Korean students’ (N = 6491) entity and incremental theories over three years. Results showed that both entity and incremental theories increased over time. The intercept and the slope of entity theory were negatively related with the intercept and the slope of incremental theory, respectively. In line with Dweck’s theoretical framework, increases in incremental theory were found to predict SAT achievement via mastery-approach goals, whereas increases in entity theory predicted SAT achievement via performance-approach goals. The results indicate that different types of achievement goals play unique roles in mediating the relation between changes in implicit theories and SAT achievement.     

A novel current-sharing scheme based on magamp

The magamp （magnetic amplifier） is widely used in power supplies due to its low cost, simplicity and other advantages. This paper discusses a novel application of the magamp in switching power supplies, where the magamp is used to regulate pulse width modulation （PWM） instead of power signal in the main circuit. This method extends the application of the magamp in power supplies, and makes it possible to further regulate control signal when PWMs have been generated. Based on this applica- tion, a new current-sharing （CS） scheme using the magamp is proposed, which uses a modified inner loop CS structure. In this scheme PWMs are generated by one main controller, and CS is achieved by regulating PWMs using a magamp in each module. Compared with traditional application of the magamp, the new CS scheme can be used in most topologies and only requires magamps of low power capacity. Then a test circuit of parallel power supply is developed, in which CS is achieved by a PWM regulator with the magamp. The proposed scheme is also used to upgrade an electroplate power to make it capable of paralleling supplies. Experimental results show that the proposed scheme has good CS performance.