3-6岁幼儿家长对幼儿园保教工作的评价及期望研究——基于新疆兵团S市汉、维、回及其他民族家长的问卷调查

不同文化背景的家长对教育有不同的看法和需求,深入探究新时期家长的教育期望和需求成为提升幼儿园保教质量的重要课题。本研究以幼儿园家长为对象,从汉、维、回及其他民族3-6岁幼儿家长对幼儿园保教工作的态度入手,分析汉、维、回及其他少数民族家长对幼儿园保教工作的评价和期望两个方面的差异,据此为幼儿园进一步了解不同民族家长教育观念、促进家园沟通、增进家园合作、提升幼儿园保教质量提供参考和建议。     

家园合作中父母参与程度的现状调查——基于新疆兵团S市幼儿园的问卷调查

利用“幼儿园家庭教养方式调查研究”基础数据,本研究从家长参与家园合作活动的频率、内容和方式三个维度考察家园合作中父母的参与程度问题,研究表明新疆兵团s市家长参与频率非常低,参与家园合作活动的内容单一,呈现出不平等的单向交流方式。同时,研究认为幼儿园性质是影响家园合作中父母参与程度的重要因素,而家长族别、文化程度和家庭户籍状况与家长参与程度无显著相关。最后,研究分析了家园合作工作中幼儿园与家长之间的关系,提出公办幼儿园和民办幼儿园促进家告参与的教师理念与策略,使家长参与更具实效性。     

基于FDTD方法的电波在等离子体中传输特性

根据时域有限差分(Finite Difference Time Domain, FDTD)法的基本原理,分析了等离子体的物理场特性及数值计算,介绍了飞行器再入时等离子鞘的形成以及等离子体相对介电常数对波的衰减,通过三维FDTD和二维FDTD模拟了电磁波在等离子体中的传播情况,证明了FDTD方法是解决电磁波在复杂媒质中传播的一种有效方法,并探究了飞行器再入段黑障区通信的理论和方法。     

基于方位特征序列的地雷鉴别算法

在使用低频超宽带合成孔径雷达(UWB-SAR)对地雷进行探测的过程中,根据目标电磁散射随方位角和入射角的变化特性,提出一种利用双峰间距和频率凹点特征沿方位向变化的隐马尔科夫模型(HMM)鉴别算法。该算法首先针对目标感兴趣区域(ROI)图像估计其各方位回波响应,然后利用时频原子提取时域双峰间距和频率凹点,进而得到随方位角变化的特征序列,再通过SAR工作时方位角和入射角的变化特点以及训练样本确定HMM参数,并在此基础上计算疑似目标新的特征矢量,采用马氏距离进行判别。实验结果表明了本文所提方法在目标鉴别方面的有效性。     

Dynamic regulation on innovation and adoption of green technology with information asymmetry

This study investigates a regulator's dynamic policy to motivate firms' research on and adoption of green technology. In the proposed model, a firm makes unobservable efforts and can hide the technology's arrival from the regulator to avoid adoption costs. We find that the optimal policy follows a simple structure and induces part-time efforts, rather than the maximal effort reported in previous studies. In particular, the regulator should offer no subsidy before the arrival of a technology report, provide a one-time subsidy contingent upon that report, and always set a termination deadline. At the deadline, the firm is forced to select an external option that is associated with social costs. The optimal report-based subsidy decreases with time. Under the optimal policy, the firm works until an effort deadline, makes no effort thereafter, and reports the technology as soon as it arrives. This study also characterizes the necessary and sufficient conditions under which the optimal policy reduces to one that leads, in terms of throughout time, to effort that is maximal or minimal. Our results indicate that policymakers should implement a policy that compensates firms more in the present and less in the future.     

Numerical investigation of the failure mechanism of cubic concrete specimens in SHPB tests

Cylindrical specimens are commonly used in Split Hopkinson pressure bar (SHPB) tests to study the uniaxial dynamic properties of concrete-like materials.In recent years,true tri-axial SHPB equipment has also been developed or is under development to investigate the material dynamic properties under tri-axial impact loads.For such tests,cubic specimens are needed.It is well understood that static material strength obtained from cylinder and cube specimens are different.Conversion factors are obtained and adopted in some guidelines to convert the material strength obtained from the two types of specimens.Previous uniaxial impact tests have also demonstrated that the failure mode and the strain rate effect of cubic specimens are very different from that of cylindrical ones.However,the mechanical background of these findings is unclear.As an extension of the previous laboratory study,this study performs numerical SHPB tests of cubic and cylindrical concrete specimens subjected to uniaxial impact load with the validated numerical model.The stress states of cubic specimens in relation to its failure mode under different strain rates is analyzed and compared with cylindrical specimens.The detailed analyses of the numerical simulation results show that the lateral inertial confinement of the cylindrical specimen is higher than that of the cubic specimen under the same strain rates.For cubic specimen,the corners are more severely damaged because of the lower lateral confinement and the occurrence of the tensile radial stress which is not observed in cylindrical specimens.These results explain why the dynamic material strengths obtained from the two types of specimens are different and are strain rate dependent.Based on the simulation results,an empirical formula of conversion factor as a function of strain rate is proposed,which supplements the traditional conversion factor for quasi-static material strength.It can be used for transforming the dynamic compressive strength from cylinders to cubes obtained from impact tests at different strain rates.     

一种纯方位跟踪中的自适应滤波算法

针对纯方位被动目标跟踪中扩展卡尔曼滤波算法易发散的不足,提出了一种自适应的改进算法。该算法利用极大后验噪声估计器Sage-Husa对虚拟观测噪声进行实时在线估计,动态补偿线性化带来的误差。算法的对比仿真分析结果表明,AEKF较之EKF滤波效果有所改善,增强了稳定性,提高了精度,为水下纯方位被动目标跟踪的实现提供一种新的方法。     

国内外安全标准现状与发展及其对构建国防工业安全标准体系的启示

介绍了国外发达国家、先进组织机构安全标准及体系的现状与特点,分析了国内安全标准的制修订情况和危险化学品、防尘防毒安全生产标准体系的分类与构成。在分析国防科技工业安全标准现状的基础上,提出了构建国防工业安全标准体系的主要任务和实施要求。     

基于智能Agent的军事后勤计划生成方法

军事后勤计划是一个复杂的过程,包括地理上分布的组织和信息的协同、繁杂的计算和分析.这使得在有限的时间内制定好后勤计划变得非常困难.基于Agent的后勤计划系统(LPS)是为了后勤计划者开发的支持系统.在LPS中用智能Agent建立军事后勤计划过程中的事务处理、组织或信息实体交互的模型,收集和分析相关信息,自动生成军事后勤计划.     

叶片式磁流变液减振器三维磁场有限元分析

介绍了2种车用叶片式MRF减振器结构方案.利用ANSOFT电磁场分析软件对2种不同结构方案的减振器进行三维磁场有限元分析,得到磁场分布相对比较理想的一种方案,并对该结构方案进行了改进.仿真分析表明,针对所讨论的叶片式MRF减振器,线圈的安匝数1 500为最优;用电工硅钢替代电工纯铁作为铁芯材料,所产生的磁感应强度更大,在缝隙处能达到1.161 4～1.355 T.