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Choosing configurations of transmission line tower grounding by back flashover probability value

Dmitry KUKLIN

《能源前沿（英文）》 2016年 第10卷 第2期   页码 213-226 doi: 10.1007/s11708-016-0398-6

摘要： There is a considerable number of works devoted to electrical characteristics of grounding. These characteristics are important in general. However, in application to grounding of transmission line towers they are not enough to determine what grounding construction is preferable in some particular case, because these characteristics are calculated or measured apart from the grounded object, and only limited number of current (or voltage) source waveforms is used. This paper indicates reasons in favor of the fact that to choose the optimum design of grounding, the calculation model should include the tower as it is. The probability of back flashover, which provides both qualitative and quantitative estimate of the grounding structure efficiency, can be taken as the criterion for the grounding design. The insulation flashover probability is calculated on the basis of engineering method, which evaluates breakdown strength of insulation for nonstandard waveshapes, and probability data on lightning currents. Different approaches are examined for identifying the back flashover probability, as not only amplitudes but also other parameters can be taken into account. Finite-difference time-domain method is used for calculations of transients. It is found that lightning current waveform can greatly influence calculated back flashover probability value.

关键词： grounding     transmission line tower     back flashover probability     FDTD method    

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Discussion on back-to-back two-stage centrifugal compressor compact design techniques

Lei HUO, Huoxing LIU

《机械工程前沿（英文）》 2013年 第8卷 第4期   页码 390-400 doi: 10.1007/s11465-013-0278-2

摘要：

Design a small flow back-to-back two-stage centrifugal compressor in the aviation turbocharger, the compressor is compact structure, small axial length, light weighted. Stationary parts have a great influence on their overall performance decline. Therefore, the stationary part of the back-to-back two-stage centrifugal compressor should pay full attention to the diffuser, bend, return vane and volute design. Volute also impact downstream return vane, making the flow in circumferential direction is not uniformed, and several blade angle of attack is drastically changed in downstream of the volute with the airflow can not be rotated to required angle. Loading of high-pressure rotor blades change due to non-uniformed of flow in circumferential direction, which makes individual blade load distribution changed, and affected blade passage load decreased to reduce the capability of work, the tip low speed range increases.

关键词： back-to-back     two-stage     centrifugal compressor     design     Internal flow    

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DFIG sliding mode control fed by back-to-back PWM converter with DC-link voltage control for variable

Youcef BEKAKRA,Djilani BEN ATTOUS

《能源前沿（英文）》 2014年 第8卷 第3期   页码 345-354 doi: 10.1007/s11708-014-0330-x

摘要： This paper proposes an indirect power control of doubly fed induction generator (DFIG) with the rotor connected to the electric grid through a back-to-back pulse width modulation (PWM) converter for variable speed wind power generation. Appropriate state space model of the DFIG is deduced. An original control strategy based on a variable structure control theory, also called sliding mode control, is applied to achieve the control of the active and reactive power exchanged between the stator of the DFIG and the grid. A proportional-integral-(PI) controller is used to keep the DC-link voltage constant for a back-to-back PWM converter. Simulations are conducted for validation of the digital controller operation using Matlab/Simulink software.

关键词： doubly fed induction generator (DFIG)     wind turbine     back-to-back pulse width modulation (PWM)     DC-link voltage     sliding mode control    

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Renewable synthetic fuel: turning carbon dioxide back into fuel

《能源前沿（英文）》 2022年 第16卷 第2期   页码 145-149 doi: 10.1007/s11708-022-0828-6

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Acupuncture is ineffective for chronic low back pain? A critical analysis and rethinking

Xuqiang Wei, Baoyan Liu

《医学前沿（英文）》 2021年 第15卷 第5期   页码 767-775 doi: 10.1007/s11684-020-0785-6

摘要： Acupuncture is a promising treatment for relieving pain and improving lower back function in clinical practice. However, evidence from randomized clinical trials (RCTs) remains controversial. Most RCTs conclude that acupuncture procedures for chronic low back pain (CLBP) had no significant difference in efficacy and belonged to placebo. We carefully reviewed and analyzed the methodology and implementation of sham acupuncture in RCTs. Controversial evidence of acupuncture for CLBP is only a microcosm of the evaluation methodological limitation of acupuncture. Inappropriate selection of sham acupuncture controls, rigorous RCT research models, and incorrect interpretation of results may contribute to negative evidence. Evaluating and disregarding the holistic efficacy of acupuncture with an explanatory RCT model based on evaluation drugs may be unwise. Moreover, sham acupuncture is often proven to be non-inert, unreasonable, and with low fidelity. Pitfalls of the explanatory RCT model and sham acupuncture design should be avoided. Establishing a new evaluation system that is in line with the clinical characteristics of acupuncture and obtaining high-quality evidence are difficult but promising tasks.

关键词： chronic low back pain     sham acupuncture     acupuncture     methodology     therapeutic evaluation    

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Analytical method of capsizing probability in the time domain for ships in the random beam seas

LIU Liqin, TANG Yougang, LI Hongxia

《结构与土木工程前沿（英文）》 2007年 第1卷 第3期   页码 361-366 doi: 10.1007/s11709-007-0048-5

摘要： The methods for constructing safe basins of ships and predicting their survival probability in random waves were studied. The nonlinear differential equation of the rolling motion of ships in random beam seas was established considering nonlinear damping, nonlinear restoring moment, and random waves. The random rolling differential equation was solved in the time domain by applying the harmonic acceleration method and by synthetically considering the instantaneous state of ships and the narrowband wave energy spectrum. The numerical simulation of random capsizing course was brought forward, the safe basins were constructed for safe navigation, and the survival probabilities of ships were calculated. As an example, the safe basins on the rolling initial value plane were constructed for a 30.27-meter-long fishing vessel according to different initial conditions and random wave parameters. The survival probabilities of the fishing vessel under different significant wave heights were predicted. Thus, the survival probabilities of ships in random seas can be predicted quantitatively by the proposed method.

关键词： different     survival probability     different significant     nonlinear differential     narrowband    

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木块在小尺寸轰燃实验中的点燃及预测模型

季经纬,宋虎,杨立中,范维澄

《中国工程科学》 2003年 第5卷 第7期   页码 62-66

摘要：

利用小尺寸轰燃实验台对松木和杉木的点燃性能进行了研究。该实验台能够提供接近实际火灾的燃烧环境，实验具有较好的可重复性。在锥形量热计实验的基础上提出了一种新的材料热辐射引燃判据。采用实验测得的轰燃实验台上层热烟气温度的平均值，结合热辐射引燃判据计算了木材在轰燃实验台中的点燃情况。

关键词： 轰燃     木材     点燃    

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Take back and treatment of discarded electronics: a scientific update

Ab STEVELS, Jaco HUISMAN, Feng WANG, Jinhui LI, Boyang LI, Huabo DUAN

《环境科学与工程前沿（英文）》 2013年 第7卷 第4期   页码 475-482 doi: 10.1007/s11783-013-0538-8

摘要： This paper indicates that the performance of tack-back and treatment of electronic waste (e-waste) system can be improved substantially. This can be reached by better taking into account in a better way the big variety in material composition and potential toxicity of electrical and electronic products – from a technical, organizational and regulatory perspective. Realizing that there is no ‘one size fit for all’ and combining smart tailor made solutions with economic of sale will result in the best environmental gain/cost ratio. Several examples show how science and engineering have supported or will support this approach.

关键词： e-waste     take back     treatment     substantially    

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Transmission probability method based on triangle meshes for solving the unstructured geometry neutron

WU Hongchun, LIU Pingping, ZHOU Yongqiang, CAO Liangzhi

《能源前沿（英文）》 2007年 第1卷 第2期   页码 158-166 doi: 10.1007/s11708-007-0020-z

摘要： The fuel assembly or core with unstructured geometry is frequently used in the advanced reactor. To calculate the fuel assembly, the transmission probability method (TPM) is widely used. However, the rectangular or hexagonal meshes are mainly used in the TPM codes for the normal core structure. The triangle meshes are most useful for expressing the complicated unstructured geometry. Even though the finite element method and Monte-Carlo method are well suited for solving the unstructured geometry problem, they are very time-consuming. Therefore, a TPM code based on the triangle meshes is developed here. This code was applied to the hybrid fuel geometry, and compared with the results of the MCNP code and other codes. The results of the comparison were consistent with each other. The TPM with triangle meshes can thus be applied to the two-dimensional arbitrary fuel assembly.

关键词： unstructured geometry     assembly     transmission probability     TPM     rectangular    

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全尺寸交流500 kV输电杆塔复合横担的雷电闪络特性 Article

王乾, 梁曦东, 沈余峰, 刘书明, 左周, 高岩峰

《工程（英文）》 2023年 第23卷 第4期   页码 130-137 doi: 10.1016/j.eng.2021.09.021

摘要：

架空输电线路（OTL）一直以来都是电力传输的主要方式。随着输电电压和输电容量的迅速提高，输电杆塔的尺寸也随之增加，造成土地资源的大量占用。考虑到线路复合绝缘子的优异性能，复合横担有望成为这一问题的解决方案。在本文中，作者制备了一个安装有复合横担的全尺寸交流（AC）500 kV输电杆塔，并施加了不同极性的雷电过电压。借助高速相机记录了流注-先导放电的过程，确认了闪络的主要路径。通过测量闪络电压并根据空气密度和湿度对结果进行修正，证实了放电的极性效应。继而，根据杆塔结构和闪络特性计算了杆塔的耐雷水平。基于全尺寸试验的结果与分析，确认了复合横担的可行性，并提出了结构优化方案。

关键词： 复合横担     输电杆塔     雷电闪络     流注放电     耐雷水平    

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Evaluating effect of chloride attack and concrete cover on the probability of corrosion

Sanjeev Kumar VERMA, Sudhir Singh BHADAURIA, Saleem AKHTAR

《结构与土木工程前沿（英文）》 2013年 第7卷 第4期   页码 379-390 doi: 10.1007/s11709-013-0223-9

摘要： Corrosion of reinforced concrete (RC) structures is one of the significant causes of deterioration of reinforced concrete (RC) structures. Chlorination is a major process governing the initiation and advancement of the injurious corrosion of steel bars. Now, several researches on the chlorination of concrete structures have been ongoing around the world. Present article reviews several recently performed chlorination studies, and from results of a field survey evaluates the effect of chloride content on the probability of corrosion and the influence of concrete compressive strength on the chloride content and penetration, also evaluates the effect of concrete cover over the chloride content of the RC structures at rebar depth and on the probability of corrosion.

关键词： concrete     chloride     reinforcement     corrosion     deterioration     cover    

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综论大坝原型反分析及其应用

顾冲时,吴中如

《中国工程科学》 2001年 第3卷 第8期   页码 76-81

摘要：

在研究大坝原型反分析及其应用研究现状的基础上，提出了反分析中急待解决的热点问题，并对这些热点问题进行了探讨，介绍了一些新的分析理论和方法。

关键词： 大坝     原型反分析     应用    

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Simulation of grid connection and maximum power point tracking control of brushless doubly-fed generator in wind power system

Hicham SERHOUD, Djilani BENATTOUS

《能源前沿（英文）》 2013年 第7卷 第3期   页码 380-387 doi: 10.1007/s11708-013-0252-z

摘要： In this paper, based on the analysis of the mathematical model in a common synchronous reference frame of the brushless doubly-fed generator (BDFG), the grid connection strategy and maximum energy extraction control were both analyzed. Besides, the transient simulation of no-load model and generation model of the BDFG have been developed on the MATLAB/Simulink platform. The test results during cutting-in grid confirmed the good dynamic performance of grid synchronization and effective power control approach for the BDFG-based variable speed wind turbines.

关键词： brushless doubly-fed generator (BDFG)     modeling     grid connection control     back-to-back pulse-width modulation (PWM) converter     wind power generation    

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Using hybrid models to predict blood pressure reactivity to unsupported back based on anthropometric

Gurmanik KAUR,Ajat Shatru ARORA,Vijender Kumar JAIN

《信息与电子工程前沿（英文）》 2015年 第16卷 第6期   页码 474-485 doi: 10.1631/FITEE.1400295

摘要： Accurate blood pressure (BP) measurement is essential in epidemiological studies, screening programmes, and research studies as well as in clinical practice for the early detection and prevention of high BP-related risks such as coronary heart disease, stroke, and kidney failure. Posture of the participant plays a vital role in accurate measurement of BP. Guidelines on measurement of BP contain recommendations on the position of the back of the participants by advising that they should sit with supported back to avoid spuriously high readings. In this work, principal component analysis (PCA) is fused with forward stepwise regression (SWR), artificial neural network (ANN), adaptive neuro-fuzzy inference system (ANFIS), and the least squares support vector machine (LS-SVM) model for the prediction of BP reactivity to an unsupported back in normotensive and hypertensive participants. PCA is used to remove multi-collinearity among anthropometric predictor variables and to select a subset of components, termed ‘principal components’ (PCs), from the original dataset. The selected PCs are fed into the proposed models for modeling and testing. The evaluation of the performance of the constructed models, using appropriate statistical indices, shows clearly that a PCA-based LS-SVM (PCA-LS-SVM) model is a promising approach for the prediction of BP reactivity in comparison to others. This assessment demonstrates the importance and advantages posed by hybrid models for the prediction of variables in biomedical research studies.

关键词： Blood pressure (BP)     Principal component analysis (PCA)     Forward stepwise regression     Artificial neural network (ANN)     Adaptive neuro-fuzzy inference system (ANFIS)     Least squares support vector machine (LS-SVM)    

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Surgical robotics: A look-back of latest advancement and bio-inspired ways to tackle existing challenges

Yang LIU, Jing LIU

《机械工程前沿（英文）》 2012年 第7卷 第4期   页码 376-384 doi: 10.1007/s11465-012-0352-1

摘要：

This article is dedicated to present a review on existing challenges and latest developments in surgical robotics in attempts to overcome the obstacles lying behind. Rather than to perform an exhaustive evaluation, we would emphasize more on the new insight by digesting the emerging bio-inspired surgical technologies with potentials to revolutionize the field. Typical approaches, possible applications, advantages and technical challenges were discussed. Evolutions of surgical robotics and future trends were analyzed. It can be found that, the major difficulties in the field of surgical robots may not be properly addressed by only using conventional approaches. As an alternative, bio-inspired methods or materials may shed light on new innovations. While endeavors to deal with existing strategies still need to be made, attentions should be paid to also borrow ideas from nature.

关键词： minimally invasive surgery     surgical robotics     haptic feedback     miniaturization     bio-inspiration     bionics    

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标题 作者 时间 类型 操作

Choosing configurations of transmission line tower grounding by back flashover probability value

Dmitry KUKLIN

期刊论文

Discussion on back-to-back two-stage centrifugal compressor compact design techniques

Lei HUO, Huoxing LIU

期刊论文

DFIG sliding mode control fed by back-to-back PWM converter with DC-link voltage control for variable

Youcef BEKAKRA,Djilani BEN ATTOUS

期刊论文

Renewable synthetic fuel: turning carbon dioxide back into fuel

期刊论文

Acupuncture is ineffective for chronic low back pain? A critical analysis and rethinking

Xuqiang Wei, Baoyan Liu

期刊论文

Analytical method of capsizing probability in the time domain for ships in the random beam seas

LIU Liqin, TANG Yougang, LI Hongxia

期刊论文

木块在小尺寸轰燃实验中的点燃及预测模型

季经纬,宋虎,杨立中,范维澄

期刊论文

Take back and treatment of discarded electronics: a scientific update

Ab STEVELS, Jaco HUISMAN, Feng WANG, Jinhui LI, Boyang LI, Huabo DUAN

期刊论文

Transmission probability method based on triangle meshes for solving the unstructured geometry neutron

WU Hongchun, LIU Pingping, ZHOU Yongqiang, CAO Liangzhi

期刊论文

全尺寸交流500 kV输电杆塔复合横担的雷电闪络特性

王乾, 梁曦东, 沈余峰, 刘书明, 左周, 高岩峰

期刊论文

Evaluating effect of chloride attack and concrete cover on the probability of corrosion

Sanjeev Kumar VERMA, Sudhir Singh BHADAURIA, Saleem AKHTAR

期刊论文

综论大坝原型反分析及其应用

顾冲时,吴中如

期刊论文

Simulation of grid connection and maximum power point tracking control of brushless doubly-fed generator in wind power system

Hicham SERHOUD, Djilani BENATTOUS

期刊论文

Using hybrid models to predict blood pressure reactivity to unsupported back based on anthropometric

Gurmanik KAUR,Ajat Shatru ARORA,Vijender Kumar JAIN

期刊论文

Surgical robotics: A look-back of latest advancement and bio-inspired ways to tackle existing challenges

Yang LIU, Jing LIU

期刊论文