远程实验系统管理机制的研究与实现

以基于实验硬件设备的远程实验系统为对象,提出了一种适用于实验人数和实验设备数不匹配情况下关于实验权限分配的管理机制。在该管理机制下,远程实验系统由现场部分、管理机以及若干远程终端组成,以共享变量网络编程技术,实现系统中三方实验信息的互通。以传感器实验对该管理机制进行了测试,结果表明,多人同时参与远程实验时,远程实验者能获得相应实验权限,在实验人数大于实验平台数的情况下,远程实验系统能正常有序运行。     

Stochastic optimal control of first-passage failure for rectangular thin plate vibration model under gaussian white-noise excitations

A rectangular thin plate vibration model subjected to inplane stochastic excitation is simplified to a quasinonintegrable Hamiltonian system with two degrees of freedom. Subsequently a one-dimensional Ito? stochastic differential equation for the system is obtained by applying the stochastic averaging method for quasi-nonintegrable Hamiltonian systems. The conditional reliability function and conditional probability density are both gained by solving the backward Kolmogorov equation numerically. Finally, a stochastic optimal control model is proposed and solved. The numerical results show the effectiveness of this method.     

特定消谐变频调速实验装置的研制

研制了变频调速原理和特定消谐技术相结合的实验装置,通过控制电路中的模数转换器对存储器高位地址的切换实现变压;改变循环加法计数器的计数脉冲频率实现变频。在逆变电路中采用了三菱公司的智能功率模块,简化了系统结构,提高了整个系统的可靠性和经济性。理论分析和实验结果表明:将特定消谐技术应用于变频调速系统后在节能和环保方面具有优越性能。该实验装置便于分析特定消谐技术的特点和变频调速的运行规律。     

Revisiting the effects of project-based learning on students’ academic achievement: A meta-analysis investigating moderators

Project-based learning is generally considered an alternative to traditional, teacher-led instruction. However, there is a noticeable lack of meta-analyses with regard to determining its overall effects on students' academic achievement, and what study features may moderate the impacts of project-based learning. This study thus performed a meta-analysis to synthesize existing research that compared the effects of project-based learning and those of traditional instruction on student academic achievement. Forty-six effect sizes (comparisons) extracted from 30 eligible journal articles published from 1998 to 2017 were analyzed, representing 12,585 students from 189 schools in nine countries. The results showed that the overall mean weighted effect size (d₊) was 0.71, indicating that project-based learning has a medium to large positive effect on students' academic achievement compared with traditional instruction. In addition, the mean effect size was affected by subject area, school location, hours of instruction, and information technology support, but not by educational stage and small group size.     

变精度粗糙集与粗糙集属性约简特征比较

通过具体问题,阐明了经典粗糙集模型分类质量、相对正域、决策类下近似具有非单调递减特征,变精度粗糙集模型在约简过程中分类质量和相对正域会出现跳跃现象,约简过程具有不稳定性.需要针对3者分别建立模型,使属性约简变得多样化.     

随机需求下缺货延期补给的易变质产品的库存策略

我们考虑需求率为随机波动函数且依赖于产品销售价格,当产品销售价格P固定;允许缺货,缺货部分延期供给,拖后率是β（t）=：e^-kt,k〉0,t是等待时间时。研究了单一易变质产品的最优订购策略。采用周期盘点的（T,S）库存策略,即每隔相同的订购周期时长T,将库存水平补充到S,在不考虑固定订购成本及订购提前期的前提下,短缺量部分延期供给,建立了库存模型。利用连续函数性质和泰勒展开分析了易变质产品最优订购策略的求解方法,给出算例并进行仿真,得到了问题的近似最优解。     

旅游业最优运输方案中单位运价的灵敏度分析

通过对旅游业最优运输方案中非基变量的检验数的分析,分别对非基变量和基变量对应的单位运价的灵敏度进行了讨论,得到为使最优方案不变时单位运价的变化范围。从而在单位运价随气候、道路、燃油等因素发生变化时给旅游企业决策者提供指导意见。     

Simplexmethod建模研讨

目的 Linear Programming的simplexmethod建模求最优解。方法应用simplexmethod.结果建立了LinearProgramming的数学模型并用simplexmethod求得了最优解.结论因为单纯形表反映了Linear Programming的所有信息,故用simplexmethod可简便地求得最优解.simplexmethod的基本思路是：先将Linear Programming用sim-plexmethod划为标准型,根据问题的标准型,进行初等行变换,将主元素列除主元素化为1外其余的元素均化为0,当基变量值全为非负时,问题就得到了最优解.     

科尔曼报告与中国教育装备史研究

从科尔曼研究报告的结论出发,对教育装备在教育均衡和学生学业中的作用问题提出研究需求方面的思考。指出科尔曼报告的局限性,并认为可以通过中国教育装备发展历史的研究来诠释和解决这一问题。     

一种不确定性机器人的变结构控制

考虑机器人的不确定项,首先利用反馈控制技术,把基于拉格朗日方程的多关节机器人动力学模型转化成一线性状态方程.然后基于此状态方程,运用变结构控制思想,并结合李雅普诺夫函数设计出一种新的机器人鲁棒控制器,这种控制器能够保证机器人机械臂的跟踪误差渐近收敛到零点.无论是理论推导还是实验仿真都说明了所设计的控制器有着很好的鲁棒性和有效性.