Study on Development of Light Aluminum Step by Using Finite Element Analysis

In order to ensure the safe operation of the escalator,the step as a part of transporting passengers,the design will consider a high safety factor,which will increase the weight,the manufacturing cost,and the energy consumption of the steps band operation.Therefore,in order to reduce the weight and ensure the strength and stiffness of the step,through the optimization design,the number of reinforcing rib supports of the step tread plate and riser plate is increased,and the thickness of the step tread plate and riser plate is moderately reduced,so as to achieve the purpose of reducing the weight of the step and reducing the manufacturing cost and operating energy consumption.Through the finite element analysis and testing of the new type step design,Its strength and stiffness fully meet the requirements of GB 16899-2011 and EN 115-1:2017 standards,and the breaking force also meets the industry standards,so that the manufacturing and operating costs of the product can be reduced to improve the competitiveness of the product market.

Performance improvement in stepped solar still modified by sponge layer

In this paper,the experimental investigation on the performance improvement of conventional stepped solar still is conducted.The steps are covered by the porous material to improve the performance of the conventional device and increase the evaporation rate.All the parameters,including the temperature on the glass surface,the water temperature inside the evaporation zone,and the amount of water produced in both conventional and modified stepped solar stills are measured and compared.The efficiency of two devices and their exergy efficiency have been calculated.Finally,the economic analysis of both devices has been done to check the economic feasibility of the modified device.The amount of freshwater generated during one day was 2244.4 and 3076.2 mL/m^(2),respectively for the conventional and modified stepped solar stills.As a result,the amount of water produced in one day by modified stepped solar still is 35.5% more than the conventional one.Also,the costs for the conventional and modified stepped solar stills have been calculated as 0.0359 and 0.029$/(L·m^(-2)),respectively.

INFLUENCE OF SHOT AND STEP RESPONSE ON PARAMETRIC SENSITIVITY UNDER THE STIMULUS-RESPONSE OF ANALYSIS

Shot and step response measurements were carried out with inert bed and adsorption bed both under iso-thermal conditions.Parameter values were determined from a time domain analysis of the measured inputand response signal.Sensitivity test in the parameter values showed that shot response measurements maygive more reliable parameter values than step measurements.Since Kubin[1]and Kucera[2]proposed a parameter estimation technique based on a moment methodfor adsorption system,attention has been focused on dynamic input-output measurements with variouspacked bed systems for the parameter estimation.The object of this work is to compare shot and step re-sponse measurements and see which measurement gives more reliable parameter values.

Francis Turbine and Governor Improved Models Considering Step Closing Law of Guide Vanes for Power System Stability Analysis

The Francis turbine governing system models in PSD-BPA can’t precisely reflect the actual characteristics. Endeavor was done in this paper to solve the problem. An improved model of actuating mechanism was developed, which could reflect the step closing characteristic of hydro guide vanes. The effect of the inflection point value of actuating mechanism on load rejection was analyzed based on simulation. The non-linear Francis turbine model with power versus gate position module was researched in this paper. Based on field test, comparisons of simulation results with measured data were presented. The analysis demonstrates that the improved models of Francis turbine and governor proposed in this paper are more realistic than the models of BPA, and can be applied in power system simulation analysis better.

TWO-STEP MECHANISM IN HETEROGENEOUS CATALYSIS AND DYNAMIC ANALYSIS

Recent development of the dynamic analysis technique has made it possible to measure separately kinetic parameters of a catalytic reaction as well as to study the effect of catalyst preparation parameters. But its application is still limned to first-order reaction. This work is aimed to demonstrate in some detail that,by comparison of the reaction rate expressions with the two-step mechanism used in catalytic kinetics and dynamic analysis, these methods can be extended to non-first-order reaction, and the kinetic parameters measured by dynamic techniques are interpreted for different reaction mechanisms.

A Contrastive Genre Analysis of Chinese and American University Admission Brochures

This study mainly uses the move and step analysis to conduct a contrastive genre analysis on the selected 20 Chinese ad-mission brochures(CABs) and 20 American admission brochures(AABs).Differences in moves,move sequences and step arrange-ments have revealed themselves in this comparison.Firstly,Chinese university admission brochures cast more focus on basic infor-mation about the university,the application procedure and admission criteria,while American universities,besides offering such in-formation,also emphasize the promotional function of the admission brochures.They use appealing and creative moves to commer-cially‘sell'advantages of the university to the potential applicants.Secondly,based on Kress & van Leeuwen's visual grammarsymbolic meaning,images and colors in admission brochures are also explored and analyzed as language.For one thing,after count-ing the frequency of the four categories of images,namely portrait,campus scenery,campus life pictures and graphs,it is foundthat,compared with CABs,AABs have a highly more obvious tendency in using images.The images are used as an effective tool toincrease the sense of credibility,identity-recognition,attract reader's attention,and help understanding,making the facts and in-formation more intuitive.For another thing,the main colors used in the brochures are yet another noticeable feature.Especially inAmerican brochures,universities tend to use their‘traditional colors' in the brochure to achieve a sense of consistency.Some Chi-nese brochures also follow this promotional strategy,yet a large percentage of them do not use any recognizable colors other thanthe printed black and white.Based on these differences,suggestions are put forward from perspectives including choice of movesand steps to improve the quality of CABs,hopefully raising their acceptance in the international level.

NUMERICAL ANALYSIS AND EXPERI-MENT OF UNSTEADY THERMAL FIELD OF ROTOR PLATE FOR EDDY CURRENT RETARDER

The physical model based on heat transfer theory and virtual boundary method for analyzing unsteady thermal field of rotor plate for eddy current retarder used in automobile is established and boundary conditions are also defined. The finite element governing equation is derived by Galerkin method. The time differential item is discrete based on Galerkin format that is stable at any condition. And a new style of varying time step method is used in iteration process. The thermal field on the rotor plate at the radial and axle directions is analyzed and varying temperature at appointed points on two side-surfaces is measured. The testing and analytical data are uniform approximately. Finite element method can be used for estimating thermal field of the rotor plate at initial design stage of eddy current retarder.

Sensitivity analysis of pull-in voltage for RF MEMS switch based on modified couple stress theory

An approximate analytical model for calculating the pull-in voltage of a stepped cantilever-type radio frequency （RF） micro electro-mechanical system （MEMS） switch is developed based on the Euler-Bernoulli beam and a modified couple stress theory, and is validated by comparison with the finite element results. The sensitivity functions of the pull-in voltage to the designed parameters are derived based on the proposed model. The sensitivity investigation shows that the pull-in voltage sensitivities increase/decrease nonlinearly with the increases in the designed parameters. For the stepped cantilever beam, there exists a nonzero optimal dimensionless length ratio, where the pull-in voltage is insensitive. The optimal value of the dimensionless length ratio only depends on the dimensionless width ratio, and can be obtained by solving a nonlinear equation. The determination of the designed parameters is discussed, and some recommendations are made for the RF MEMS switch optimization.

Near-infrared spectroscopy(NIRS) evaluation and regional analysis of Chinese faba bean(Vicia faba L.)

To analyze the nutritional composition of faba bean(Vicia faba L.) seed, estimation models were developed for protein, starch, oil, and total polyphenol using near infrared spectroscopy(NIRS). Two hundred and forty-four samples from twelve producing regions were measured in both milled powder and intact seed forms. Partial least squares(PLS) regression was applied for model development. The model based on ground seed powder was generally superior to that based on the intact seed. The optimal seed powder-based models for protein, starch, and total polyphenol had coefficients of correlation(r2) of 0.97, 0.93 and 0.89, respectively. The relationship between nutrient contents and twelve producing areas was determined by two-step cluster analysis. Three distinct groupings were obtained with region-constituent features, i.e., Group 1 of high oil, Group 2 of high protein, and Group 3 of high starch as well as total polyphenol. The clustering accuracy was 79.5%. Moreover, the nutrition contents were affected by seeding date, longitude, latitude, and altitude of plant location. Cluster analysis revealed that the differences in the seed were strongly influenced by geographical factors.

Theoretical Analysis of Nano Displacement of Nanometer Precision Actuator and Its Application

The kind of micro-/nano-meter precision actuator in cludes a piezoelectric one, an electric deformation one, a magnetic deformation one, a mechanical one, and a mechanical and electrical one. This paper puts forw ard a mechanical and electrical step actuator of nanometer precision, which cons ists of a step motor of large fine-dividing number of step angle, shaft couplin gs, a decelerator of large decelerating ratio, a screw mechanism and a pole of U shape, and has the minimum step displacement of 10 nm, the step displac ement precision of 1 nm, the step frequency of 4 kHz, the maximum loadability of 20 kg. In order to achieve the nano displacement of nano precision by this actu ator, the theoretical analysis of stress and strain must be made on the transmit ting course of nano displacement of the actuator, and their numerical simulation is done by computer. The paper establishes the constitutive equation of 3-D stress and the strain co ordinate equation of the composing system of the nanometer precision actuator. A s a result, the theoretical relation among stress and strain and displacement is set up. The torque of the step motor produces a thrust to transmit the displace ment of the above system of the parts and assemblies to output the needed nano d isplacement. In the case of concrete analysis and calculating, the comparing met hod of film-roof is applied to analyze and calculate the motor axis, decelerato r axes, the screw pole and the nut. The analysis method of plane stress and stra in is used to analyze and calculate the shaft couplings and gears. The analysis method of beam stress and strain is used to do the pole of U shape. These calcul ation is belong to the physical non-linear problem. Under the condition of smal l deformation, the analysis way of the finite element can be combined with the a bove analyses and calculations. The elementary analysis results show that the na nometer precision actuator can be applied in STM nanofabrication.

Numerical method and analysis of computational fluid mechanics for photoelectric semiconducting detector

We propose a modified upwind finite difference fractional step scheme for the computational fluid mechanics simulations of a three-dimensional photoelectric semiconductor detector. We obtain the optimal l^2-norm error estimates by using the techniques including the calculus of variations, the energy methods, the induction hypothesis, and a priori estimates. The proposed scheme is successfully applied to the simulation of the photoelectric semiconductor detectors.

Homotopy Analysis Method for Solving Initial Value Problems of Second Order with Discontinuities

In this paper, the standard homotopy analysis method was applied to initial value problems of the second order with some types of discontinuities, for both linear and nonlinear cases. To show the high accuracy of the solution results compared with the exact solution, a comparison of the numerical results was made applying the standard homotopy analysis method with the iteration of the integral equation and the numerical solution with the Simpson rule. Also, the maximum absolute error, , the maximum relative error, the maximum residual error and the estimated order of convergence were given. The research is meaningful and I recommend it to be published in the journal.

Occupational burnout in nurses:a concept analysis

Objective:This paper aims to clarify the concept of occupational burnout(OB)as well as develop appropriate methods to relieve or prevent OB in the nursing profession.Methods:Walker and Avant's eight-step approach of concept analysis was applied.Results:OB was defined as a chronic form of work-related stress.Accurately,it was characterized by emotional exhaustion,depersonalization/cynicism,and reduced personal accomplishment/inefficacy.Antecedents of burnout included(a)demographic characteristics;(b)chronic exposure to work-related stressors;(c)quantitative and qualitative job demands;(d)lack of job resources;and(e)personality traits.Consequences involved(a)individual’s unfavorable quality of life;(b)negative impact on the organization;and(c)poor services quality.Although the Maslach Burnout Inventory(MBI)is perceived as an ideal tool to measure burnout and hence,it is used worldwide,whether this instrument fits to measure this concept for nurses has still not yet been verified and thus further research is needed.Conclusions:By proposing a comprehensive definition of the concept,this analysis contributes to recognition of the process of OB of nurses.All nurses are vulnerable to OB.Hence,burnout in nursing needs to be recognized as a critical factor in the delivery of safe patient care.It proposes that the prevention of OB would be achieved through team communication training,mindfulness group,education,etc.

Genre Analysis on Introduction of English Major Masters' Graduation Thesis

The introduction of the academic paper, as a type of discourse, are not only an indispensable part of the thesis, but also a kind of social behavior with communicative purpose. The introductions are the essence of academic papers, so it is particularly important for postgraduates to write English introduction. Therefore, the introduction of academic writing, as a genre, has been widely studied for many years. This study analyzes a 50-research-article corpus of English introductions chosen at random with theories relating to genre and genre analysis. These research articles from masters' graduation thesis in the field of applied linguistics(Research Article, i.e. for RA) are analyzed from macro-level and micro-level. And this study is to explore English postgraduates how to choose genre structure, language forms and the communicative purpose that the introductions should achieve. The result shows that some English introductions of the masters' graduation thesis differ from the international general pattern in frequency and quantity of moves, due to the influence of the context. To some extent, this study is significant in teaching academic paper writing.

A Genre Analysis of Online English Job Advertisement

In the recent years, posting online job advertisements has become a major way for a growing number of multinational cor-porations to publicize their employment information and to recruit job seekers. Nevertheless, the language and space of online jobadvertisement are uneven, which may affect the companies to attract and communicate with the potential candidates. Based on thetheoretical framework of moves and steps analysis suggested by Swales(1990) and Bhatia(2004), the study aims to explore thestructural pattern of this genre and to examine the lexico-grammatical features of each move and step. After analyzing four piecesof job advertisements retrieved from different recruiting websites, the study reveals that there are six moves in the whole structureof online job advertisement, among these, three moves are obligatory, named: establishing credential, introducing the position, to-gether with specifying required qualifications, skills, and experiences. Meanwhile, in each move, the positive adjectives, verbs, andfirst person are frequently used to serve the promotional function, and therefore to intensify the communicative purpose. The studymay contribute to the application of genre analysis in business English teaching, and also be instructive to the reading and writingof online job advertisement.

人行悬索桥的步行参数研究

以九峰山人行悬索桥为观测点,采用视频记录与人工筛选相结合的方法获取了2236个行人样本的实测数据,进而统计得到人行悬索桥上的行人步行参数(步频、步幅和步速)的分布特性和统计值,并给出了人行悬索桥上的步频-步速、步幅-步速和步频-步幅之间的转换关系式,得到以下结论:1)在人行悬索桥上,全部行人的步行参数都服从正态分布,即步频~N(1.726,0.258)Hz、步幅~N(0.596,0.094)m、步速~N(1.013,0.260)m/s,它们的合理性也在某工程实例的应用中得以验证;2)人行悬索桥上的行人步行参数的均值(标准差)要小于(大于)其他行走环境所统计得到的行人步行参数的均值(标准差);3)中国人的步频和步幅的均值(标准差)都小于(大于)西方人的步频和步幅的均值(标准差).因此,在设计我国的人行悬索桥时,不能直接采用其他人种和行走环境的行人步行参数的统计值,而应采用适合于人行悬索桥的步行参数.

基于季节性碳交易机制的园区综合能源系统低碳经济调度

为有效提高碳排放配额分配的合理性,并且避免年度结算时碳排放量超标导致环境污染加剧问题,提出基于奖惩因子的季节性碳交易机制,以园区综合能源系统(park integrated energy system,PIES)为对象进行低碳经济调度。首先,构建包含能量层–碳流层–管理层的综合能源系统(integrated energy system,IES)运行框架,建立电气热多能流供需动态一致性模型;其次,分析系统内“日–季节–年度”碳排放特性,打破传统应用指标法的配额分配方法,采用灰色关联分析法建立碳排放配额分配模型,并基于奖惩阶梯碳价制定季节性碳交易机制;最后,以系统内全寿命周期运行成本及碳交易成本最小为目标,对执行季节性碳交易机制的PIES进行低碳经济调度,分析长时间尺度下季节性储能参与调度的减碳量。搭建IEEE 33节点电网5节点气网7节点热网的PIES,并基于多场景进行算例分析,验证此调度方法能够实现零碳经济运行,保证系统供能可靠性,为建立零碳园区奠定理论基础。

基于定子电流法的绕线转子无刷双馈发电机偏心故障研究

绕线转子无刷双馈电机在船舶轴带发电以及风力发电等领域中具有良好的应用前景。转子偏心是一种常见的机械故障,威胁着现代化工业体系的稳定运转,因此实现其状态检测和故障诊断非常关键。由于无刷双馈电机具有特殊的定、转子绕组结构以及复杂的气隙磁场,因此传统的故障检测方法无法直接用于该类电机。该文通过定子电流法提取了功率绕组电流的特征频率分量作为故障指标,实现对静偏心、动偏心以及混合偏心的无创诊断。建立故障电机的时步有限元模型,并通过详细的故障机理分析,得出不同类型的偏心故障可能导致的特征频率信号。最后,以一台2/4对极无刷双馈电机为例,并通过有限元仿真、样机试验验证解析法的结论,为绕线转子无刷双馈电机偏心故障的精准检测提供了理论依据。

黄土地基阶梯型截面桩承载模型试验与计算

为研究黄土地基阶梯型截面桩的荷载传递机理,通过室内模型试验与有限元计算,分析阶梯型截面桩竖向静荷载下的桩身轴力、桩侧摩阻力、桩顶沉降和桩身不同深度荷载分担比,并探索了变径比对其工作性能的影响,并对其进行优化设计。结果表明:在相同荷载下,阶梯型截面桩的桩顶沉降明显小于等截面桩,当变径比在0.8~0.9时,沉降控制效果最佳,其材料利用率最高;若二者极限承载力相同时,阶梯型截面桩的最高材料利用率为等截面桩的1.06倍。阶梯型截面桩为摩擦型桩,变截面位置土体对桩体具有支承作用,其变径处底面土体能承担部分桩顶荷载。桩侧能够分担更多桩顶荷载,减轻桩端土体承载,当变径比在0.8~0.9时,侧摩阻力发挥程度更高。在桩体用料相同时,与等截面桩相比,阶梯型截面桩能大幅度提高承载能力。

阶段矿房法二步骤采场地压控制研究

在阶段矿房二步骤开采时,为了减小上盘岩移量,常采纳采场中部切槽并向上盘、下盘两侧回采,从而缩短采场暴露时间,以便减小上盘岩移量。当地压达到流变发生的条件后,缩短采场暴露时间并不能有效控制上盘巷道发生岩移破坏。为此,利用三维连续体快速拉格朗日分析数值模拟采场上盘地压,并根据流变理论分析,采纳低松弛预应力大直径钢绞线锚索支护上盘顶板以便减小上盘地压,从而克服发生流变变形的应力条件。结果表明:在上盘岩体上施加支护抗力可减小或消除高地压导致的流变变形;采纳7排7.0 m长的锚索、每排6根支护上盘顶板后大幅度减小了上盘岩移量,但采场第2分层上排锚索及一步骤采场第3分层局部锚索的锚固力超过设计值;采纳8排7.0 m长的锚索、一步骤采场每排7根、二步骤采场每排6根支护上盘顶板后,即使回采底柱,锚索锚固力也不会达到设计值。监测表明,大直径钢绞线锚索支护后上盘岩移量减小到一般不超过6 mm。