oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2020 ( 5 )

2019 ( 36 )

2018 ( 277 )

2017 ( 274 )

Custom range...

Search Results: 1 - 10 of 14475 matches for " LEI Yongjun "
All listed articles are free for downloading (OA Articles)
Page 1 /14475
Display every page Item
A Smart Substation Field Secondary Device Testing Technique Based on Recurrence Principle  [PDF]
Kanjun Zhang, Lei Chen, Yongjun Xia, Yang Lei, Xin Shu, Hengxuan Li, Ting Wang, Zhenan Du
Journal of Power and Energy Engineering (JPEE) , 2014, DOI: 10.4236/jpee.2014.24035
Abstract: According to the demand of substation secondary device dynamic performance testing, a smart substation field testing technique based on recurrence principle is proposed in the paper, and the characteristics of smart substation secondary device digitization and information sharing are used by the technique. The principle of testing technique is as follow: the digital simulation model is constructed on the basis of the substation’s actual construction, then the simulating data highly similar to substation’s actual electric quantity transient process is generated, at last, the substation digital secondary device can be tested by using data “recurrence” technique. The testing technique is verified and applied by constructing testing system, the application results show that the technique can effectively perform field test on the dynamic performance of digital secondary device, and the technique has good engineering implementation and application value.
Evaluation of energy transfer and utilization efficiency of azo dye removal by different pulsed electrical discharge modes
YongJun Shen,LeCheng Lei,XingWang Zhang
Chinese Science Bulletin , 2008, DOI: 10.1007/s11434-008-0251-3
Abstract: The degradation of an azo dye, acid orange 7 (AO7), caused by different high voltage pulsed electrical discharge modes (spark, streamer and corona discharge) induced by the various initial conductivities was investigated. A new type of pulsed high voltage source with thyratron switch and Blumlein pulse forming net (BPFN) was used. The typical discharge waveforms of voltage, current, power, pulse energy and the pictures of spark, streamer and corona discharge modes were presented. The results indicated that pulsed electrical discharges led to complete decolorization and substantial decrease of the chemical oxygen demand (COD) of the dye solution. The main intermediate products were monitored by GC-MS. The discharge modes changed from spark to streamer and to corona discharge, and the streamer length decreased with the liquid conductivity increasing. At a constant input power, the peak voltage, peak current, peak power and energy per pulse of the three discharge modes ranked in the following order: spark > streamer > corona. The effective energy transfer efficiency of AO7 removal was higher for spark discharge (57.2%) than for streamer discharge (40.4%) and corona discharge (27.6%). Moreover, the energy utilization efficiency of AO7 removal for spark discharge was 1.035×109 mol/J, and for streamer and corona discharge they were 0.646×10 9 and 0.589×10 9 mol/J. Both the energy transfer efficiency and the energy utilization efficiency of spark discharge were the highest.
Evaluation of energy transfer and utilization efficiency of azo dye removal by different pulsed electrical discharge modes
SHEN YongJun,LEI LeCheng &,ZHANG XingWang,

科学通报(英文版) , 2008,
Abstract: The degradation of an azo dye, acid orange 7 (AO7), caused by different high voltage pulsed electrical discharge modes (spark, streamer and corona discharge) induced by the various initial conductivities was investigated. A new type of pulsed high voltage source with thyratron switch and Blumlein pulse forming net (BPFN) was used. The typical discharge waveforms of voltage, current, power, pulse energy and the pictures of spark, streamer and corona discharge modes were presented. The results indicated that pulsed electrical discharges led to complete decolorization and substantial decrease of the chemical oxygen demand (COD) of the dye solution. The main intermediate products were monitored by GC-MS. The discharge modes changed from spark to streamer and to corona discharge, and the streamer length decreased with the liquid conductivity increasing. At a constant input power, the peak voltage, peak current, peak power and energy per pulse of the three discharge modes ranked in the following order: spark > streamer > corona. The effective energy transfer efficiency of AO7 removal was higher for spark discharge (57.2%) than for streamer discharge (40.4%) and corona discharge (27.6%). Moreover, the energy utilization efficiency of AO7 removal for spark discharge was 1.035×109 mol/J, and for streamer and corona discharge they were 0.646×10 9 and 0.589×10 9 mol/J. Both the energy transfer efficiency and the energy utilization efficiency of spark discharge were the highest. Supported by National Natural Science Foundation of China (Grant Nos. 20336030, 90610005, 20576120 and U0633003), and Distinguished Youth Foundation of Zhejiang Province (Grant No. RC 02060)
双材料界面裂纹的加料有限元方法

YANG Junhui
, LEI Yongjun, MENG Shangyang

- , 2015, DOI: 10.11887/j.cn.201503019
Abstract: 为解决求解双材料界面裂纹应力强度因子等断裂参量的困难,在常规单元位移模式中引入界面裂纹尖端位移场,构建加料界面裂纹单元和过渡单元的位移模式,推出了加料有限元方程。采用不同的加料单元和过渡单元配置方案,建立了方形板中心界面裂纹和矩形板单边斜界面裂纹的加料有限元模型,求解有限元方程直接得到应力强度因子,与解析解的结果对比,表明该方法具有较高的精度,可方便地推广应用于界面裂纹的计算分析中。
The enriched finite element method is used to solve the stress intensity factors for two bonded dissimilar materials containing a crack along the bond. By appending the displacement expressions for an interface crack to the common element, the enriched and transition element displacement model are obtained; the enriched finite element equation is derived. Two enrichment schemes are introduced to establish the finite element models for square plate center interface crack and rectangular plate unilateral oblique interface crack. The stress intensity factors are calculated directly from the finite element equation. The results, which are obtained by compared with analytical results, demonstrate that the enriched finite element method is a convenient and high precision calculation method for interface crack problems.
Relationship of Post-Stroke Aphasic Types with Sex, Age and Stroke Types  [PDF]
Jingfan Yao, Zaizhu Han, Yanli Song, Lei Li, Yun Zhou, Weikang Chen, Chunxue Wang, Yongjun Wang, Yumei Zhang
World Journal of Neuroscience (WJNS) , 2015, DOI: 10.4236/wjns.2015.51004
Abstract: Aim:To explore what is the relationship of the types of post-stroke aphasia with sex, age andstroke types.Methods:Retrospective analysis was administrated on data of 421 patients with acutestroke. Western battery aphasia was used to measure aphasiac type and aphasia quotient (AQ)score. The patients were divided into three age groups: young, middle-aged and elderly. The stroketypes were classified into cerebral infraction (CI) and intracerebral hemorrhage (ICH). Results: All subjects were right-handed, which males and females accounted for 69.60% and 30.40%, respectively. There were 116 cases of Broca’s aphasia (85 males), 35 cases of Wernicke’s aphasia (20 males),15 cases of conductive aphasia (10 males), 63 cases of transcortical motor aphasia (50 males), 11 cases of transcortical sensory aphasia (8 males), 27 cases of transcortical combined aphasia (13 males), 73 cases of anomic aphasia (47 males) and 81 cases of global aphasia (60 males). Male patients (69.60%) have a significantly higher morbidity of aphasia than that of females (30.40%) after stroke (χ2
Relationship of Post-Stroke Aphasic Types with Sex, Age and Stroke Types  [PDF]
Jingfan Yao, Zaizhu Han, Yanli Song, Lei Li, Yun Zhou, Weikang Chen, Yongmei Deng, Yongjun Wang, Yumei Zhang
World Journal of Neuroscience (WJNS) , 2015, DOI: 10.4236/wjns.2015.51004
Abstract: Aim: To explore what is the relationship of the types of post-stroke aphasia with sex, age and stroke types. Methods: Retrospective analysis was administrated on data of 421 patients with acute stroke. Western battery aphasia was used to measure aphasiac type and aphasia quotient (AQ) score. The patients were divided into three age groups: young, middle-aged and elderly. The stroke types were classified into cerebral infraction (CI) and intracerebral hemorrhage (ICH). Results: All subjects were right-handed, which males and females accounted for 69.60% and 30.40%, respectively. There were 116 cases of Broca’s aphasia (85 males), 35 cases of Wernicke’s aphasia (20 males), 15 cases of conductive aphasia (10 males), 63 cases of transcortical motor aphasia (50 males), 11 cases of transcortical sensory aphasia (8 males), 27 cases of transcortical combined aphasia (13 males), 73 cases of anomic aphasia (47 males) and 81 cases of global aphasia (60 males). Male patients (69.60%) have a significantly higher morbidity of aphasia than that of females (30.40%) after stroke (χ2 = 11.57
Experimental and Numerical Study of the Effect of Surround Protection Technique on the Strain Measurement for Offshore Jacket Platform  [PDF]
Yongjun Xu
Engineering (ENG) , 2011, DOI: 10.4236/eng.2011.35056
Abstract: For strain measurement on offshore jacket platform in deep water, waterproof of strain foil is always an important issue, especially, due to the high pressure in deep water. The waterproof is difficult in two places, one is between the matrix structure and the protection structure, and another is between the lead wires and the protection structure. The surround protection technique discussed in this paper is conventional and ideal, and can be operative for a long time, up to five years. In this method, a metal case and tube is added on the local position, which increases the local rigidity, but the effect on the measurement of strain is not well studied. In this paper, the effect of the surround protection technique on the strain measurement is studied by using numerical and experimental methods, and the results show that the measurement error is well in the range permitted by engineering practice.
Localization Algorithms of Underwater Wireless Sensor Networks: A Survey
Guangjie Han,Jinfang Jiang,Lei Shu,Yongjun Xu,Feng Wang
Sensors , 2012, DOI: 10.3390/s120202026
Abstract: In Underwater Wireless Sensor Networks (UWSNs), localization is one of most important technologies since it plays a critical role in many applications. Motivated by widespread adoption of localization, in this paper, we present a comprehensive survey of localization algorithms. First, we classify localization algorithms into three categories based on sensor nodes’ mobility: stationary localization algorithms, mobile localization algorithms and hybrid localization algorithms. Moreover, we compare the localization algorithms in detail and analyze future research directions of localization algorithms in UWSNs.
黏弹性基底上阻尼碳纳米管的动力学特性
张大鹏, 雷勇军
ZHANG Dapeng
, LEI Yongjun

- , 2015, DOI: 10.11887/j.cn.201506026
Abstract: 采用欧拉梁模型建立了有阻尼碳纳米管在黏弹性基底上的动力学问题分析模型。通过引入非局部理论、广义Maxwell黏弹性模型、速度相依的外阻尼模型及黏弹性基底模型推导出碳纳米管动力学分析的欧拉梁振动控制方程。在Kelvin-Voigt黏弹性模型基础上,分别给出无基底和全基底支撑时碳纳米管固有频率的一般解析表达式,并分析讨论全基底时的多种典型情况。然后利用传递函数方法求解出一般边界条件下振动控制方程的封闭解。以某单壁碳纳米管为例,得到不同边界条件下该单壁碳纳米管的前四阶固有频率,并分析了碳纳米管非局部参数、黏弹性参数、基底刚度及长度等影响因素对固有频率和阻尼因子的影响情况。结果表明,文中所建的动力学分析模型及计算方法对解决碳纳米管在黏弹性基底上的动力学问题准确有效。
The dynamic characteristic analysis model of damped carbon nanotubes on viscoelastic foundations was built by using Euler-Bernoulli beams. The nonlocal viscoelastic theories, general Maxwell viscoelastic model, velocity-dependent external damping model and viscoelastic foundation model were employed to deduce the governing equation of Euler-Bernoulli beams for dynamic characteristics analysis of carbon nanotubes. On the basis of Kelvin-Voigt model, new general analytical expressions for the natural frequencies of damped carbon nanotubes with no foundation and full foundation were obtained respectively and some typical special cases at full foundation were discussed. Then a transfer function method was developed to obtain a closed-form and uniform solution for the vibration governing equation under arbitrary boundary conditions. Considering a single-walled carbon nanotube as a numerical example, the first four natural frequencies with different boundary conditions were obtained, and the effects of the nonlocal and viscoelastic constants, the foundation stiffness coefficient and length on the natural frequencies and damping factors were analyzed. Results demonstrate the efficiency of the proposed model and the analysis methods in solving dynamic problems of damped carbon nanotubes on viscoelastic foundations.
双材料V型切口应力强度因子的加料有限元分析

YANG Junhui
, HAN Junli, LEI Yongjun, MENG Shangyang

- , 2016, DOI: 10.11887/j.cn.201601025
Abstract: 应用Williams本征函数展开和线性变换求解V型切口端部渐进位移场。将该位移场加入常规等参单元位移模式中,构造双材料V型切口加料单元和过渡单元的位移模式,推导加料有限元方程。建立带V型缺口双材料三点弯曲梁试件和直角界面端平面问题的加料有限元模型,求解有限元方程可直接得到应力强度因子。计算结果与用其他方法得到的数据吻合,验证了方法的正确性,可用于双材料V型切口结构断裂特性计算分析。
The V-notch asymptotic displacement field was derived through an approach based on the Williams’ series expansion and linear algebraic transforms. By incorporating the displacement expressions to the common isoparametric elements, the enriched and transition element displacement model were obtained, and then the enriched finite element equation was derived consequently. The enriched finite element model for a V-notched bi-material three-point bending beam and an orthogonal bonded materials interface end plane problem were constructed. The stress intensity factors can be solved directly from the finite element equation. Comparisons between the results and the published data computed with other algorithm indicate that the present method is correct and can be used to analyze the fracture property of the V notched bi material structure.
Page 1 /14475
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.