纯物质过冷熔体中自由枝晶生长相场模型的自适应有限元法模拟

基于自适应有限元方法,通过求解表征纯物质相场模型的非线性抛物型方程,研究镍过冷熔体中不同起伏情况下单个完整等轴枝晶的演化过程.模拟结果表明:采用自适应有限元方法求解相场模型时结果更接近真实物理模型,在计算终止时整个计算域节点数仅为2.79×105个,远小于采用相同网格间距普通方法的1.6×106个,较大不同计算域对枝晶尖端速度的平衡值影响不大;随着起伏强度的增大,枝晶尖端获得更高的温度梯度,等温线波动更大,一次枝晶臂表面失稳,二次枝晶臂向过冷溶液中凸起的趋势越强,二次枝晶臂越发达.     

面向农民的现代远程教育学习测评改革初探——以教育部“一村一名大学生计划”为例

通过现代远程教育手段开展面向农民的学历教育学习测评多沿用普通高校的学习测评体系,存在测评理念陈旧、方向偏差,主体单一、手段落后,注重结果评价、忽略过程评价等问题;需从加大形成性考核和开卷考试比例、注重过程和能力测评,建设网络题库、促进学测评一体化,实时推出预约考试、满足多样化需求等几个方面进行改革和探索,为学生提供灵活多样的学习测评服务.     

A trusted mobile payment environment based on trusted computing and virtualization technology

In this paper, we propose a trusted mobile payment environment （TMPE） based on trusted computing and virtualization technology. There are a normal operating system （OS） and a trusted OS （TOS） in TMPE. We store the image of TOS in a memory card to hinder tampering. The integrity of TOS is protected by means of a trusted platform module （TPM）. TOS can only be updated through a trusted third party. In addition, virtualization technology is applied to isolate TOS from normal OS. Users complete ordinary affairs in normal OS and security-sensitive affairs in TOS. TMPE can offer users a highly protected environment for mobile payment. Moreover, TMPE has good compatibility in different hardware architectures of mobile platforms. As the evaluation shows, TMPE satisfies the requirement of mobile payment well.     

关于中专实施学生评价体育教师教学的研究

探讨中专学生、体育教师对于学生参与体育教师教学评价的看法.采用质与量并进的研究方法,对某地区12所中专院校的72位体育教师和200名学生进行调查,学生部分以问卷方式进行资料收集,体育教师部分采用半开放式与开放式题型,以访谈方式进行资料收集,最后整理问卷和访谈资料,并对资料进行分析研究.     

顶岗实习管理机制提高就业率的研究与实践——以辽阳职业技术学院为例

通过对辽阳职业技术学院生物制药专业2010级、2011级学生顶岗实习情况的调查分析,构建"五化三落实"顶岗实习管理机制,提出顶岗实习是培养高技能人才的重要环节,是充分就业的有效途径.     

从“总角之交”到“白首唱和”——张含与杨慎的交游考

张合作为明代滇产诗人群中的杰出代表,他的诗歌涵盖明代云南社会的方方面面,而究其大部份诗作来说,离不开他与杨慎的唱酬交游内容。从“知人论世”的文学研究角度出发,考证这些诗歌作品背后二人的交游史实,了解二人交往的心路历程是有一定价值的。自张、杨二人的父辈交往入手,通过对张、杨二人的诗歌研读,考释出二人在杨慎入滇前后的交往唱酬经历及杨慎在滇的部分行程,或对以后张含、杨慎的诗歌研究都有所裨益。     

Some recent theoretical progress in Higgs boson and top quark physics at hadron colliders

The test of the Standard Model and search for New Physics signal are main aim of LHC experiment. With the increasing of the measurement accuracy at the LHC, it is a major task in future to exceed the current accuracy of the theoretical predictions for important processes, in particular ones involving Higgs boson and top quark. In this review we briefly summarize some recent theoretical progress in Higgs boson and top quark physics, especially the fixed-order and resummation predictions in QCD at both the Tevatron and the LHC.     

Observation of directional change of core field inside flux ropes within one reconnection diffusion region in the Earth’s magnetotail

Two consecutive magnetic flux ropes, separated by less than 30 s （△t 〈 30 s）, are observed within one magnetic reconnection diffusion region without strong guide field in the Earth＇s magnetotail by Cluster multispacecraft. The flux ropes are characterized by bipolar signatures of the south-north magnetic field component Bz accompanied with strong core magnetic field By, intense current J and density depletions inside of them. In spite of the small but non-trivial global scale negative guide field （-By）, there exists a directional change of the core fields of two flux ropes, i.e., -By for the first one, and ＋By for the second one. The directions of the core fields are the same as the ambient cross-tail magnetic field component （By） just outside of flux ropes. Therefore, we suggest that the core field of flux ropes is formed by compression of the local preexisting By and that the directional change of core field is due to the change of local preexisting By. Such a change in ambient By might be caused by some microscale physics.     

Influence of the amplitude ratio between two terahertz pulses on two-dimensional spectroscopy

The influence of the amplitude ratio between the two THz pulses on two-dimension THz spectroscopy （2DTS） has been studied theoretically via a classical method in which the expressions for the second-order nonlinearity were derived using perturbation approach, and the THz pulses were not treated as a delta function. Three types of nonlinear sources i.e., anharmonicity, nonlinear damping, and nonlinear coupling, are considered in a single mode system. The simulation results demonstrated that the amplitude ratio had a notable influence on the 2DTSs, and different sources have different influences. This study is promising for guiding future experiments.     

Computational diffusion kinetics and its applications in study and design of rare metallic materials

Computational diffusion kinetics(CDK),with a spirit of and being coupled with the computational thermodynamics(CT,or called as the CALPHAD technique),plays increasingly important role in the alloy design/optimization and microstructure control during the processing of advanced metallic materials.This paper is to highlight recent progress of CDK in research with great focus on novel Ti and Zr alloys,which was largely performed in the authors’group.It ends with one representative example of the applications of CDK,coupled with CT,quantitative phase field,and three-dimensional(3D)statistical calculation,in designing the heattreatment schedule for the dual phase(αβ)Ti–6Al–4V alloys.