高速列车节能运行策略实验验证方法

控制并改善列车运行策略、节约运行能耗是铁路运输的传统研究领域,有着广泛的研究成果。为更加有效地比较不同运行策略的节能效果,验证运行策略的传动系统控制可行性,提出了高速列车节能运行策略的实验验证方法。运行策略将在电气传动系统连续负载模拟与运行仿真联合平台上进行验证。对三种列车运行策略进行了仿真和实验对比,仿真分析和实验结果相符合,验证了所提出的基于动态规划原理的固定时分策略优势,说明了实验验证方法的可行性。搭建实际列车等功率负载模拟平台,将有效验证节能运行策略的可行性。

实验验证教学方法在中职数字电路触发器中的实用分析

就我国中职电子信息专业而言,数字电路属于该专业最基础的课程,此外,其也被称为电子产品整机装配与维修、单片机原理和应用及集成电路等课程的必要前提。基于我国中职学生特点:思维方法单一、文化基础较弱、畏难情绪重及创新意识能力不强等。此外,作为中职执教教师,必须对学生实践能力、动手能力予以足够重视,并积极培养学生学习兴趣,其中,将实验验证教学方法应用于中职数字电路触发器教学中,是实现中职学生相关能力提高的重要途径。

关于《验证机械能守恒定律》实验方法的改进

1 改进背景《验证机械能守恒定律》实验是高中物理必做的一个学生实验。现行教材中本实验原理是让重锤只在重力作用下物体做自由落体运动,遵守机械能守恒定律,实验时让重物从静止下落,验证公式是1/2mv_n^2=mgh_n,借助打点记时器打出的纸带,(如图1)利用直尺测出重物下落的高度h_n(纸带上打第一点到该点的距离)和该时刻(该点)的瞬时速度v_n,即可验证机械能守恒定律。

少林正骨精微生物限度检查方法验证试验

目的建立少林正骨精微生物限度检查方法。方法采用人工感染五种阳性菌株的方法,对少林正骨精进行细菌、霉菌及酵母菌的计数检验以及控制菌的检验。结果细菌、霉菌及酵母菌采用离心沉淀集菌法+稀释法的回收率均不低于70%;控制菌采用离心沉淀集菌法检验呈阳性。结论少林正骨精的微生物限度检查细菌、霉菌及酵母菌可采用离心+稀释法;控制菌可采用离心沉淀集菌法。

增乳膏微生物限度检查方法验证试验

目的建立增乳膏微生物限度检查方法。方法采用人工感染五种阳性菌株的方法,对增乳膏进行细菌、霉菌及酵母菌的计数检验以及控制菌的检验。结果细菌采用离心沉淀集菌法、霉菌及酵母菌采用常规法的回收率均不低于70%,控制菌采用常规法检验呈阳性。结论增乳膏的微生物限度检查细菌可采用离心沉淀集菌法,霉菌、酵母菌及控制菌可采用常规法。

纺织品禁用偶氮染料的能力验证方法关键点分析

国家认证认可监督管理委员会(CNCA)早已将纺织品禁用偶氮染料的测定作为能力验证计划中A类项目之一,是中国合格评定国家认可委员会(CNAS)实验室每年能力验证必考项目之一。此检测方法的特点是:前处理过程中要求的试剂和设备多,操作步骤多,试验时间长。本文总结了作者长期的实验心得和多次能力验证的经验,对该检测方法的关键点进行了详细分析,以供CNAS能力验证参加者和纺织品实验人员参考借鉴。

口腔实验教学方法的改进研究

口腔实验教学是口腔医学教育过程中的重要组成部分,口腔实验教学的成果直接影响到学生的实践操作能力。因此,必须对学生选择合适的口腔实验教学方法,提高学生的实践操作水平。传统的口腔实验教学方法不利于提高学生的学习兴趣和积极性,因此所获得的教学效果不高。改进口腔实验教学方法,如使用以问题为基础的实验教学方法、验证性实验教学方法、延伸线实验教学方法、构建“虚拟仿真+模型评估”实验教学体系等,可显著提高学生的学习兴趣,最终提高学习效率,更好地用于临床之中。

基于用户影响力的热点话题检测方法研究

[目的/意义]对微博消息进行热点话题挖掘,进而从海量微博文本中实时找出用户关注、讨论的热点事件,是进行舆情监测、应急管理的基础。然而,现有微博热点话题检测研究却大多忽略了不同影响力用户对话题产生及传播的作用,并且检测结果直观性较差。针对此问题,提出了基于用户影响力的热点话题检测方法。[方法/过程]首先识别用户特征要素,构建用户影响力模型,计算用户影响力;然后,综合考虑主题词影响力、影响力增长速度和增长斜率,提出基于用户影响力的微博热点话题主题词抽取方法,抽取主题词簇;之后,识别核心主题词并进行热点话题关键词抽取。最后,通过实验验证方法的有效性。[结果/结论]实验结果表明:基于用户影响力的热点话题检测方法能够有效识别并直观表达出检测时间窗口内的典型热点话题;该方法能有效提升实证性热点话题识别效率,减少娱乐性热点话题的识别;通过对不同时间窗口内同一话题的关键词抽取,可以实现对相应话题的热点跟踪。

基于安全本体的信息安全知识聚合技术研究

在信息安全教育资源的构建中,为使主题爬虫更全面、准确、快速地获取教育所需的信息安全领域知识,文章通过建立信息安全领域本体,为主题提供高度专业化的精准领域定义描述;通过安全本体描述中概念间的关系,扩展主题信息的语义范围,基于最大相关度引导下的深度优先遍历方法,对爬取的网页在语义概念层进行相关性分析,以提高主题爬虫信息爬取的准确率;采用广度优先搜索策略与链接相关度计算相结合的混合爬取策略,指导主题爬虫进行页面信息的爬取,以有效提升主题爬虫的爬取效率。通过与基于关键词描述的主题爬虫的对比实验验证了该方法的有效性。

Vibration-based feature extraction of determining dynamic characteristic for engine block low vibration design

In order to maintain vibration performances within the limits of the design, a vibration-based feature extraction method for dynamic characteristic using empirical mode decomposition （EMD） and wavelet analysis was proposed. The proposed method was verified experimentally and numerically by implementing the scheme on engine block. In the implementation process, the following steps were identified to be important： 1） EMD technique in order to solve the feature extraction of vibration signals; 2） Vibration measurement for the purpose of confirming the structural weak regions of engine block in experiment; 3） Finite element modeling for the purpose of determining dynamic characteristic in time region and frequency region to affirm the comparability of response character corresponding to improvement schemes; 4） Adopting a feature index oflMF for structural improvement based on EMD and wavelet analysis. The obtained results show that IMF of signal is more sensitive to response character corresponding to improvement schemes. Finally, examination of the results confirms that the proposed vibration-based feature extraction method is very robust, and focuses on the relative merits of modification and full-scale structural optimization of engine, together with the creation of new low-vibration designs.

Dynamic analysis of new type elastic screen surface with multi degree of freedom and experimental validation

A feasible method was proposed to improve the vibration intensity of screen surface via application of a new type elastic screen surface with multi degree of freedom(NTESSMDF). In the NTESSMDF, the primary robs were coupled to the main screen structure with ends embedded into the elastomers, and the secondary robs were attached to adjacent two primary robs with elastic bands. The dynamic model of vibrating screen with NTESSMDF was established based on Lagrange's equation and the equivalent stiffnesses of the elastomer and elastic band were calculated. According to numerical simulation using the 4th order Runge-Kutta method, the vibration intensity of screen surface can be enhanced substantially with an averaged acceleration amplitude increasing ratio of 72.36%. The primary robs and secondary robs vibrate inversely in steady state, which would result in the friability of materials and avoid stoppage. The experimental results validate the dynamic characteristics with acceleration amplitude rising by62.93% on average, which demonstrates the feasibility of NTESSMDF.

Numerical simulation of dynamic process for liquid film spreading by lattice Boltzmann method and its experimental verification

Combined with the kinetic model of liquid film spreading, a new numerical method of solid-liquid-gas three-phase flow was developed for the moving of contact line, which was a hybrid method of computational fluid dynamics and lattice Boltzmalm method （LBM）. By taking the effect of molecule force in droplet and the wall surface on liquid film into account, the changing law of contact angle with different surface tensions was analyzed on glass and aluminum foil surfaces. Compared with experimental results, the standard deviation by using LBM is less than 0.5°, which validates the feasibility of LBM simulation on the dynamic process of liquid film spreading. In addition, oscillations are discovered both at the initial and end phases. The phenomenon of retraction is also found and the maximum retraction angle is 7.58°. The obtained result shows that the retraction is proved to be correlative with precursor film by tracking the volume change of liquid film contour. Furthermore, non-dimensional coefficient 2 is introduced to measure the liquid film retraction capacity.

Three-dimensional simulation of interfacial convection in CO_2–ethanol system by hybrid lattice Boltzmann method with experimental validation

By using a hybrid lattice-Boltzmann–finite-difference method(hybrid LBM–FDM method),three-dimensional simulations of solutal interfacial convection were conducted for the process of CO2absorption into ethanol.A self-renewal interface model is adopted as an interfacial perturbation model.The simulation results revealed some three-dimensional features of the induced interfacial convection,such as the development of diverging cellular flow and Rayleigh plume-like convection in liquid phase.The concentration distribution of the simulation result is validated and found to be in well agreement with the Schlieren visualization results qualitatively.Additionally,the mass transfer enhancements by interfacial convection were investigated via both simulation and experiment for the absorption process,and the mass transfer is shown to be enhanced by the interfacial convection by about two-fold comparing with that by diffusion.

Verification of Seismic Performance of Pile Foundation in Composite Ground through Experimental and Numerical Methods

A new construction method of pile foundation in composite ground, in which, prior to installing piles, the ground is improved around the heads of the piles in soft ground or ground subject to liquefaction, which is introduced in this paper. This construction method uses a combination of pile foundation construction together with common ground improvement methods, including deep mixing, preloading and sand compaction piling, and it is referred to as the composite ground pile method. Since an artificial ground with relatively high rigidity comparing with that of the original ground was formed around the pile in this method, and the seismic performance has not been made clear, thus the seismic performance of piles in composite ground was systematically analyzed through a series of centrifuge model tests and numerical analyses by using dynamic nonlinear finite element method, and a verification method for the seismic performance of piles in composite ground was proposed on the basis of the experimental and numerical results.

From electronic excited state theory to the property predictions of organic optoelectronic materials

We introduce here a work package for a National Natural Science Foundation of China Major Project. We propose to develop computational methodology starting from the theory of electronic excitation processes to predicting the opto-electronic property for organic materials, in close collaborations with experiments. Through developing methods for the electron dynamics, considering superexchange electronic couplings, spin-orbit coupling elements between excited states, electron-phonon relaxation, intermolecular Coulomb and exchange terms we combine the statistical physics approaches including dynamic Monte Carlo, Boltzmann transport equation and Boltzmann statistics to predict the macroscopic properties of opto-electronic materials such as light-emitting efficiency, charge mobility, and exciton diffusion length. Experimental synthesis and characterization of D-A type ambipolar transport material as well as novel carbon based material will provide a test ground for the verification of theory.

A displacement measurement system based on optical triangulation method

A new displacement measurement system is described in this paper according to the basic principles of traditional lasertriangulation method. The range of the traditional measuring method is enlarged by measuring in sections. Three independent CCDs, which are distributed uniformly along the optical axis, are used to achieve subsection measurement. The planemirror is regarded as a virtual detector. When imaging beam is reflected by the plane mirror, the beam is imaged on theCC D. The designed system is equivalent to add a CCD. The feasibility of the displacement measurement system is verifiedby the experiment.