检索结果-内蒙古大学图书馆

The International Conference on Recent Trends in Materials and Mechanical Engineering（ICRTMME 2011）

作者： XU Jianjun ZHANG Ya LI Bo Mechanical and Electronic Engineering Institute North University of China

ISBN: (纸本)9783037850992

Military electronic components apply in high temperature conditions has become one of the hot research field of reliability field,then the temperature characteristics of the military electronic components are known by designers is key to guarantee high reliability of military equipment under high temperature ***,a scheme of the high temperature dynamic test based on low consumed power test circuits and PC is worked out in this *** can be used for test the temperature performance of the military electronic components,and feasibility of the schemes are tested and verified by *** the changing law of the components parameter are got in this conditions which found out components parameters approximate linear in 25℃200℃,of nonlinear in large range in the very high temperature of 200℃ 350℃ conditions,which can offer some reference value to prolong lifetime of military electron device.

关键词： Military Electronic components High Temperature Dynamic testing variable parameters

来源：评论

学校读者我要写书评

暂无评论

The preconditioned iterative methods with variable parameters for saddle point problem

引用

APPLIED MATHEMATICS AND COMPUTATION 2018年 334卷 152-167页

作者： Huang, Na Ma, Chang-Feng Fujian Normal Univ Coll Math & Informat Fuzhou 350117 Fujian Peoples R China Fujian Normal Univ FJKLMAA Fuzhou 350117 Fujian Peoples R China Chinese Acad Sci Acad Math & Syst Sci Beijing 100190 Peoples R China

In this paper, by transforming the original problem equivalently, we propose a new preconditioned iterative method for solving saddle point problem. We call the new method as PTU ( preconditioned transformative Uzawa) method. And we study the convergence of the PTU method under suitable restrictions on the iteration parameters. Moreover, we show the choices of the optimal parameters and the spectrum of the preconditioned matrix deriving from the PTU method. Based on the PTU iterative method, we propose another iterative method - nonlinear inexact PTU method - for solving saddle point problem. We also prove its convergence and study the choices of the optimal parameters. In addition, we present some numerical results to illustrate the behavior of the considered algorithms. (C) 2018 Elsevier Inc. All rights reserved.

关键词： Saddle point problem Preconditioned iterative method variable parameters Optimal parameter Convergence

来源：评论

学校读者我要写书评

暂无评论

Monitoring the coefficient of variation using a variable parameters chart

引用

QUALITY ENGINEERING 2018年第2期30卷 212-235页

作者： Yeong, Wai Chung Lim, Sok Li Khoo, Michael Boon Chong Castagliola, Philippe Univ Malaya Fac Business & Accountancy Dept Operat & Management Informat Syst Kuala Lumpur Malaysia Univ Malaya Inst Math Sci Fac Sci Kuala Lumpur Malaysia Univ Sains Malaysia Sch Math Sci George Town Malaysia Univ Nantes LUNAM Univ Nantes France IRCCyN UMR CNRS Nantes France

This article is the first of its kind which proposes a variable parameters (VP) chart to monitor the coefficient of variation (CV). Formulae for various performance measures and the algorithms to optimize these performance measures are proposed. The VP CV chart consistently outperforms the five alternative CV charts in the literature, for all shift sizes. Compared to the Exponentially Weighted Moving Average (EWMA) CV2 chart, the VP CV chart outperforms it for moderate and large shift sizes, while for small shift sizes, the EWMA CV2 chart outperforms the VP CV chart. Subsequently, the VP CV chart is implemented on an industrial example.

关键词： adaptive charts average time to signal coefficient of variation expected average time to signal variable parameters

来源：评论

学校读者我要写书评

暂无评论

A variable parameters damage model for concrete

引用

ENGINEERING FRACTURE MECHANICS 2020年第0期228卷 106898-000页

作者： Qi, Huijun Li, Tongchun Liu, Xiaoqing Zhao, Lanhao Lin, Chaoning Fan, Shujie Hohai Univ Coll Comp & Informat Nanjing Peoples R China Hohai Univ Coll Water Conservancy & Hydropower Engn Nanjing Peoples R China Hohai Univ Nanjing Coll Energy & Elect Engn Nanjing Peoples R China

A novel four-parameters damage constitutive model for concrete in strain space is proposed in this paper. It is based on the Heish-Ting-Chen constitutive model and is derived in the framework of the thermodynamics of irreversible process. Because tension damage is a major fracture mode in concrete used for hydraulic structures, an equivalent strain is introduced that converts the multi-axial strain state into the equivalent tension strain to determine the tension damage. Considering the change in the equations' parameters during progressive failure, a variable parameters constitutive model is established. The parameters of the damage constitutive model are obtained by the increasing section and the decreasing section of stress-strain curve and it is demonstrated that the proposed model performs better than the regular constitutive model in the decreasing section. The numerical implementations provide a good description of the failure process as well as an accurate prediction of the behaviour of concrete.

关键词： variable parameters Damage model Concrete Fracture

来源：评论

学校读者我要写书评

暂无评论

A creep constitutive model with variable parameters for thenardite

引用

ENVIRONMENTAL EARTH SCIENCES 2016年第11期75卷 1页

作者： Wang, Junbao Liu, Xinrong Song, Zhanping Guo, Jianqiang Zhang, Qianqian Xian Univ Architecture & Technol Sch Civil Engn Xian 710055 Peoples R China Chongqing Univ Sch Civil Engn Chongqing 400045 Peoples R China Guizhou Univ Sch Civil Engn Guiyang 550003 Peoples R China

Results from the triaxial creep tests indicate that the relationship between steady creep rate of thenardite and deviatoric stress can be described with the Heard model. By combining the Kelvin model which reflects the primary creep property of rock with the Heard steady creep model, a Kelvin-Heard (K-H) creep model is constructed. However, the predicted curves from the K-H model are not in good agreement with the creep test data of thenardite. To improve the prediction precision, it is assumed that the viscosity coefficient of thenardite increases over time in primary creep stage, and an improved K-H model is proposed. Compared with the K-H model, the improved K-H model can more precisely describe the creep behavior of thenardite under a certain stress state. However, each of its parameters G, eta(infinity), a and b has different values under different deviatoric stress levels. These four parameters all decrease with the increase in deviatoric stress, which is considered to establish an improved K-H model with variable parameters for thenardite finally. Comparison with the test data shows that this model can precisely predict the creep behavior of thenardite when 25 MPa <= sigma(1) - sigma(3) <= 40 MPa.

关键词： Thenardite Creep model variable parameters Prediction

来源：评论

学校读者我要写书评

暂无评论

Economic design of variable parameters (X)over-bar control charts for processes with fuzzy mean shifts

引用

JOURNAL OF THE OPERATIONAL RESEARCH SOCIETY 2008年第8期59卷 1128-1135页

作者： Chen, Y-K Chang, H-H Natl Taichung Inst Technol Dept Logist Engn & Management Taichung Taiwan Natl Taipei Coll Business Taipei Taiwan

Modern studies have shown that the X control charts with variable parameters (VPs) detect process shifts faster than the traditional X control charts. This article developed the economic design of the VP (X) over bar control chart to determine the values of the design parameters of the chart. However, this study, different from previous studies, was focused on the process that is subject to a disturbing cause, and the occurrence of the cause can result in a fuzzy mean shift (ie the magnitude of the mean shift could not be recognized exactly). The issue of economically selecting the design parameters for the chart was firstly formulated as a mathematical programming model with a fuzzy objective function that could cope with fuzzy number type of mean shift. A fuzzy-simulation-based genetic algorithm was then employed to search for the optimal values of the design parameters from the model. An industrial example was provided to illustrate the solution procedure, and was used for comparison between the VP and the traditional X chart. Effects of model parameters on the solution of the economic design were also discussed.

关键词： economic design fuzzy-simulation-based genetic algorithm variable parameters control chart

来源：评论

学校读者我要写书评

暂无评论

Experimental Study of Helical Milling Carbon Fiber Reinforced Plastics by variable parameters

引用

EXPERIMENTAL TECHNIQUES 2024年第2期48卷 343-357页

作者： Jiao, A. Zhang, Y. Zhang, J. Li, J. Univ Sci & Technol Liaoning Coll Mech Engn & Automat Anshan 114041 Peoples R China Estun Automat Grp Nanjing 210000 Peoples R China

In order to significantly reduce the defects of hole-making on Carbon Fiber Reinforced Plastics (CFRP), a scheme on the variable parameter helical milling experiments was carried out. First, the helical milling process was analyzed. Second, using the response surface methodology (RSM) in the experiments, the max exit tear value, aperture diameter and surface roughness Ra at the intermediate area were analyzed and the optimum combination of parameters was obtained: spindle speed 8962 r/min, helical speed 60 r/min, and pitch 0.207 mm at the hole entry and exit areas;spindle speed 6242 r/min, helical speed 87 r/min, and pitch 0.205 mm at the hole intermediate area. Last, the effect of milling direction on hole-making was obtained: up milling at the hole entry and exit areas and down milling at the hole intermediate area. The superiority of variable parameter helical milling experiment was verified: there were fewer defects such as burrs and tears at hole entry and exit areas;and the surface roughness Ra was 6.39% lower, the aperture deviation was from + 0.011 mm to -0.007 mm at the hole intermediate area. Therefore, the quality of hole-making by the variable parameter helical milling scheme was significantly improved.

关键词： variable parameters Helical milling CFRP Surface roughness Ra RSM

来源：评论

学校读者我要写书评

暂无评论

An Efficiency Improvement Method for the Small Air Gap Wireless Power Transfer System With variable parameters

引用

IEEE TRANSACTIONS ON POWER ELECTRONICS 2023年第11期38卷 13443-13453页

作者： Jia, Yahui Wang, Zhihui Tang, Chunsen Zhao, Lei Li, Xiaofei Wang, Cheng Chongqing Univ Sch Automat Chongqing 401331 Peoples R China

The magnetic coupling wireless power transfer (MC-WPT) system for automatic guided vehicles is characterized by a small and unfixed air gap, which leads to significant changes in self- and mutual inductance of the magnetic coupler. In this article, an efficiency improvement method is proposed for the MC-WPT system with variable self- and mutual inductance parameters. By optimizing the design of magnetic couplers and compensation parameters, a wide range of zero-voltage switching (ZVS) operation and minimization of the reactive current are achieved. The self-inductance variation is utilized to provide a variable system input impedance, which expands the ZVS operation range with phase-shift modulation. Meanwhile, the reactive current of the resonant tank in the entire air gap range can be reduced to the minimum when the tuning parameters are designed properly. Compared with the traditional hybrid control strategies, the proposed method offers a simpler control scheme and eliminates the adverse effects caused by the self-inductance variation. A laboratory prototype is built to verify the theoretical analysis. The experimental results show that the system achieves ZVS operation and minimum reactive current within an air gap range of 20-50 mm, and efficiency reaches 91.2%.

关键词： Efficiency improvement magnetic coupling wireless power transfer (MC-WPT) variable parameters zero-voltage switching (ZVS)

来源：评论

学校读者我要写书评

暂无评论

Economic Design of the variable parameters X over bar Control Chart with a Corrected A&L Switching Rule

引用

QUALITY AND RELIABILITY ENGINEERING INTERNATIONAL 2014年第2期30卷 235-246页

作者： Guo, Zhi-Fang Cheng, Long-Sheng Lu, Zu-Di Taiyuan Univ Sci & Technol Sch Econ & Management Taiyuan Peoples R China Nanjing Univ Sci & Technol Sch Econ & Management Nanjing Jiangsu Peoples R China Univ Adelaide Sch Math Sci Adelaide SA Australia

The variable parameters (VP) X over bar control chart is more efficient than the fixed parameters X over bar control chart. However, an obvious shortcoming of the VP X over bar control chart is its excessive number of switches among different design parameters, which significantly increases the complexity of operations for administer and the costs of maintaining the control chart. Amin and Letsinger (1991) proposed a switching rule, denoted by A&L switching rule, to reduce the number of switches. In this paper, we investigated the economic design of the VP X over bar control chart by using the corrected A&L switching rule scheme, which makes some corrections to the existing study of the A&L switching rule scheme. A three-state Markov model is proposed to derive the performance measures of the suggested control chart. An expected cost model for the process is established with the cost function derived. The genetic algorithm is then employed to search for the solution for the economic design of the proposed control chart. The results obtained show that the developed model can significantly reduce the average number of the parameter's switches and save the expected cost in comparison with the conventional VP control scheme in detecting small and moderate mean shifts. A sensitivity analysis is also carried out to examine the effects of cost and model parameters on the solution of the economic design for the proposed control chart. The analysis demonstrates the expected cost per time unit is positively affected by the cost associated with a false signal, the average cost of repairs when a true signal is identified, the sampling cost and the cost associated with a switch, and is negatively affected by the cost associated with running the process in-control per hour. Copyright (c) 2013 John Wiley & Sons, Ltd.

关键词： economic design control chart a switching rule variable parameters genetic algorithm

来源：评论

学校读者我要写书评

暂无评论

The variable parameters [image omitted] Control Charts for Monitoring Autocorrelated Processes

引用

COMMUNICATIONS IN STATISTICS-SIMULATION AND COMPUTATION 2009年第4期38卷 729-749页

作者： Lin, Yu-Chang Natl Taichung Inst Technol Dept Accounting Taichung 404 Taiwan

The variable parameters (VP) [image omitted] control chart varies all control parameters from the current sample information, and results in more effective monitoring based on statistical and economic criteria. The usual assumption for designing a control chart is that the observations from the process are independent. However, for many processes, such as chemical processes, consecutive measurements are often highly correlated. In the present article, the observations are modeled as an AR(1) process plus a random error, and the properties of the VP [image omitted] charts are evaluated and studied under this model. Based on the study, the VP control scheme generally has better performance in detecting small mean shifts than the standard and the other adaptive [image omitted] charts. However, when the observations are highly autocorrelated, the complexity of the VP [image omitted] chart gives a negative effect on the performance.

关键词： Autocorrelated process Control chart First-order autoregressive process Quality control variable parameters

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：