电动外部式砼振动器常见故障与处理

较详细地阐述了电动外部式砼振动器常见故障、故障分析及造成的原因与处理方法。

浅谈“外部描述式”思想在数据库系统中的应用

本文介绍了“外部描述式”概念在数据库中的应用,使用此概念可以非常灵活的建立和修改一个新的系统。主要对“外部描述式”概念的设计思路、数据表实现和先进性进行了分析,并通过实践证明了其有效性。

高层住宅板式外部空间设计探析

我国经济建设和城镇建设的飞速发展为我国建筑行业带来了新的发展契机,纵观近些年的高层住宅建筑,板式高层住宅已经成为城镇建设中所占比重越来越大的结构形式,这种建筑结构形式的外部空间设计也就显得尤为重要,本文主要通过针对板式住宅建筑的外部空间的设计中的安全感,容积率以及住宅间距等几个问题进行阐述和分析,以期给同行提供一些经验和参考。

外部机械化室式炉装取料机的设计

简单介绍了国内大口径无缝管的生产现状及外部机械化室式炉的特点。详细阐述了外部机械化室式炉用装取料机的设备组成、工作过程及各组成部分的结构特点及功能。

外部机械化室式热处理炉设计简述

文章主要研究无缝钢管热处理炉中一种炉型——外部机械化室式热处理炉。在工艺特点、炉子结构、设备设计方面进行了归纳总结,对以后的类似工程具有借鉴意义。

街区式商业综合体界面因子与行为集聚关联性研究——以上海市三个街区式商业综合体为例

本文以上海五角场万达广场、正大乐城和金虹桥商场作为研究案例,通过实地调研和数据分析对街区式商业综合体界面形态和功能特征与集聚行为的相关性进行量化分析。研究发现:形态因子中透明度、开敞度、出入口数量对集聚行为有明显促进作用,功能因子中店面密度和有外摆餐饮占比对集聚行为有明显促进作用。最后本文以此为出发点对街区式商业综合体外部空间界面设计和外部空间组织提出设计策略和建议,以提高外部空间使用效能。

高等教育评价质量观刍议

高等教育评价现已成为世界各国高度关注的重要领域。高等教育评价的核心是对质量的探究。高等教育评价质量是个很复杂的问题 ,因为高等教育评价本身面临着困难性和可行性问题。本文旨在阐述高等教育评价质量观的不同表现形式 :不同的大学观有着不同的高等教育评价质量观 ;不同的评价主体有着不同的高等教育评价质量观 ;

RTW在某型直升机飞控系统半物理仿真中的应用

开发高性能可靠的飞控计算机是直升机研制的重要一步。在试飞之前,需要对飞控系统进行全面的仿真测试。基于Simulink的RTW工具箱和嵌入式VxWorks操作系统,提出一种进行飞控系统半物理仿真的方案。详细说明了仿真平台的组成、RTW的配置方法和生成实时仿真代码的过程。仿真时应用了RTW的外部模式,说明了其原理和具体配置方法。深入分析了RTW生成的目标文件中直升机模型信号量和参数的存取方式,并提出了一种可行的办法。最后给出仿真结果并验证了该方案的可行性,此方案已经应用于进一步的试飞工作中。

基于CPCI与LPC总线的主板BIT设计

为提高CPCI计算机设备的可靠性,准确地定位故障,减少设备的维修时间,在原计算机主板的基础上,提出了基于CPCI总线及LPC总线的故障检测卡。以故障检测和定位为目标,兼顾设备的扩展性和易用性,建立以CPLD为控制芯片,采用VHDL硬件描述语言,实现对计算机主板进行故障检测和定位的功能卡。详细介绍了BIT(built in test)卡的原理和软、硬件设计,并给出了仿真结果。仿真实验结果表明,整个设计安全可靠,移植性好,可为计算机的主板设计提供参考。

A practical robust nonlinear controller for maglev levitation system

In order to explore the precise dynamic response of the maglev train and verify the validity of proposed controller,a maglev guideway-electromagnet-air spring-cabin coupled model is developed in the first step.Based on the coupled model,the stresses of the modules are analyzed,and it is pointed out that the inherent nonlinearity,the inner coupling,misalignments between the sensors and actuators,and external disturbances are the main issues that should be considered for the maglev engineering.Furthermore,a feedback linearization controller based on the mathematical model of a maglev module is derived,in which the nonlinearity,coupling and misalignments are taken into account.Then,to attenuate the effect of external disturbances,a disturbance observer is proposed and the dynamics of the estimation error is analyzed using the input-to-state stability theory.It shows that the error is negligible under a low-frequency disturbance.However,at the high-frequency range,the error is unacceptable and the disturbances can not be compensated in time,which lead to over designed fluctuations of levitation gap,even a clash between the upper surface of electromagnet and lower surface of guideway.To solve this problem,a novel nonlinear acceleration feedback is put forward to enhancing the attenuation ability of fast varying disturbances.Finally,numerical comparisons show that the proposed controller outperforms the traditional feedback linearization controller and maintains good robustness under disturbances.

Three-dimensional analysis of natural convection in nanofluid-filled parallelogrammic enclosure opened from top and heated with square heater

A numerical study based on the finite volume method has been performed to study the three-dimension natural convection in a parallelogrammic top side opened cavity filled nanofluid with partially heated square at the bottom side.Results are obtained for different governing parameters such as nanoparticle concentration (φ) from 0 to 0.05,inclination angle of the back and front walls (α) from 5° to 75°,Rayleigh number from 10^3 to 10^5,and length of heater changer from 0.1 to 1.The main finding from the obtained result showed that the inclination angle and nanoparticle volume fraction affect the flow structure and enhance the heat transfer.

Natural frequency characteristics of thin-walled homogeneous and manifold layered cylindrical shells under pressure using energy method

Energy method for the vibration of two types of cylindrical shells,namely thin-walled homogeneous isotropic and manifold layered isotropic cylindrical shells under uniform external lateral pressure is presented.The study is carried out based on strain-displacement relationship from Love's shell theory with beam functions as axial modal function.A manifold layered cylindrical shell configuration is formed by three layers of isotropic material where the inner and outer layers are stainless steel and the middle layer is aluminum.The homogeneous cylindrical shell is made-up of isotropic one layer with stainless steel.The governing equations with uniform external lateral pressure for homogeneous isotropic and manifold layered isotropic cylindrical shells are obtained using energy functional by the Lagrangian function with Rayleigh-Ritz method.The boundary conditions that are presented at the end conditions of the cylindrical shell are simply supported-simply supported,clamped-clamped and free-free.The influences of uniform external lateral pressure and symmetrical boundary conditions on the natural frequency characteristics for both homogeneous and manifold layered isotropic cylindrical shells are examined.For all boundary conditions considered,the natural frequency of both cylindrical shells with symmetric uniform lateral pressure increases as h/R ratio increases and those considering natural frequency of the both cylindrical shells with symmetric uniform lateral pressure decrease as L/R ratio increases.

Robot motion control in mobile environment

With the problem of robot motion control in dynamic environment represented by mobile obstacles,working pieces and external mechanisms considered, a relevant control actions design procedure has been pro-posed to provide coordination of robot motions with respect to the moving external objects so that an extension ofrobot spatial motion techniques and active robotic strategies based on approaches of nonlinear control theory canbe achieved.

教育家型教师成长的三大路径

教育家型教师是具有独立的教育思想、坚定的教育理想,以及高尚的师德、师风和优秀的教育教学能力的教师。教育家型教师是人们对教师的专业发展及综合整体素质提高的最高期望。教育家型教师是教师发展的良好愿景,普通教师经过不懈的努力能够达成。教育家型教师的成长是内外因共同作用的结果。其中,教师的自我发展和职业情感是教育家型教师成长的内部驱动力,外部环境的培养为推动教育家型教师的成长创造了条件。

Oscillating Propagation of Kink in Nondissipative Frenkel-Kontorova Chain Due to External DC Force

We report the oscillating propagation of kink in a nondissipative Frenkel-Kontorova （FK） chain driven by external DC force, which is different from the usual propagation of localized modes with equal speed. When the kink moves in the opposite direction of the external DC force, the kink will be accelerated and the potential of the FK chain in the external force field is transformed to be the kinetic energy of the kink. If the kink reaches the boundary of the FK chain, the kink will be bounced back and moves in the opposite direction, then the kink will be decelerated gradually and the kinetic energy of the kink ＆ transformed to be the potential of the FK chain in the external force field. If the speed of the kink reaches zero, the kink will move in the opposite direction again driven by the external DC force, and a new oscillating cycle begins. Simulation result demonstrates exactly the transformation between the kinetic energy of the kink and the potential of the FK chain in the external force field. The interesting energy exchange is induced by the special topology of kinks, and other localized modes, such as breathers and envelope solitons, have no the interesting phenomenon.

Women＇s Position in Religious Life of Georgia and Its Peculiarities

Georgia is a country where women＇s secular and religious activities would never be strange and unprecedented. But also this is a country where women are considered impure for ritual purposes, not allowed even to come too close to the shrines or conduct liturgy; where participation in main shrine rituals or slaughter of sacrifice was and is strictly forbidden. However, there are remarkable exceptions that are shown in the article. Women＇s shrines are found almost in all regions of Georgia, but according to our field works and other ethnographic data their presence is remarkably obvious in Khevi, mountainous region of East Georgia. The study of the subject brought us to a conclusion that women in Khevi might have more rights in conducting religious rituals at shrines than in other Eastern Georgia＇s highland regions. It may be conditioned by St. Ninos＇s strong connection with the region.

Construction of Stereoscopic Teaching Mode in Ideological and Political Education Course in ＂Holistic＂ Vision

Ideological and political education aims for comprehensive development of all aspects of capacity. However, there exist following issues in our current education： emphasizing knowledge instruction while neglecting students＇ personality development; education is confined to the classroom, ignoring influence on students thinking from external environment; simplicity in teaching evaluation. To truly achieve the purpose of educating people, we should adhere to stereoscopic teaching, establish ＂people＂-centered educational philosophy, adhere to ＂all-round development＂; integrate resources in and out of school for education; establish diversified evaluation system.

Circumjacent distribution pattern of the Lungmachian graptolitic black shale(early Silurian) on the Yichang Uplift and its peripheral region

Stratigraphic hiatuses of variable time intervals within the Rhuddanian to early Aeronian （Llandovery, Silurian） are identified in the area bordering East Chongqing, West Hubei and Northwest Hunan in central China. Their distribution suggested the existence of a local uplift, traditionally named the Yichang Uplift. The diachronous nature of the basal black shale of the Lungmachi Formation crossing different belts of this Uplift signifies the various developing stages during the uplifting process. The present paper defines the temporal and spatial distribution pattern of the Yichang Uplift, which might be one of the important controlling factors for the preservation and distribution of the shale gas in this region, as it has been demonstrated that the shale gas exploration is generally less promising in the areas where more of the basal part of the Lungmachi Formation is missing. Therefore, better understanding of the circumjacent distribution pattern developed throughout the uplifting process may provide the important guidance for the shale gas exploration. The present work is a sister study to the published paper, ＂Stage-progressive distribution pattern of the Lungrnachian black graplolitic shales from Guizhou to Chongqing, Central China＂. These two studies thus provide a complete Ordovician-Silurian black shale distribution pattern in the Middle and Upper Yangtze, a region with the major shale gas fields in China.