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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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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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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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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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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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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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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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hexavalent chromium using a porous titanium flow-through electrode and intelligent prediction based on a back

《环境科学与工程前沿（英文）》 2023年 第17卷 第8期 doi: 10.1007/s11783-023-1697-x

摘要：

● Titanium-based flow-through electrode achieved high Cr(VI) reduction efficiency.

关键词： Flow-through electrode     Hexavalent chromium     Heavy metals     Neural network     Artificial intelligence    

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Day-ahead electricity price forecasting using back propagation neural networks and weighted least square

S. Surender REDDY,Chan-Mook JUNG,Ko Jun SEOG

《能源前沿（英文）》 2016年 第10卷 第1期   页码 105-113 doi: 10.1007/s11708-016-0393-y

摘要： This paper proposes the day-ahead electricity price forecasting using the artificial neural networks (ANN) and weighted least square (WLS) technique in the restructured electricity markets. Price forecasting is very important for online trading, e-commerce and power system operation. Forecasting the hourly locational marginal prices (LMP) in the electricity markets is a very important basis for the decision making in order to maximize the profits/benefits. The novel approach proposed in this paper for forecasting the electricity prices uses WLS technique and compares the results with the results obtained by using ANNs. To perform this price forecasting, the market knowledge is utilized to optimize the selection of input data for the electricity price forecasting tool. In this paper, price forecasting for Pennsylvania-New Jersey-Maryland (PJM) interconnection is demonstrated using the ANNs and the proposed WLS technique. The data used for this price forecasting is obtained from the PJM website. The forecasting results obtained by both methods are compared, which shows the effectiveness of the proposed forecasting approach. From the simulation results, it can be observed that the accuracy of prediction has increased in both seasons using the proposed WLS technique. Another important advantage of the proposed WLS technique is that it is not an iterative method.

关键词： day-ahead electricity markets     price forecasting     load forecasting     artificial neural networks     load serving entities    

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of using amorphous silicon stack as front heterojunction structure on performance of interdigitated back

Rui JIA,Ke TAO,Qiang LI,Xiaowan DAI,Hengchao SUN,Yun SUN,Zhi JIN,Xinyu LIU

《能源前沿（英文）》 2017年 第11卷 第1期   页码 96-104 doi: 10.1007/s11708-016-0434-6

摘要： Interdigitated back contact-heterojunction (IBC-HJ) solar cells can have a conversion efficiency of over 25%. However, the front surface passivation and structure have a great influence on the properties of the IBC-HJ solar cell. In this paper, detailed numerical simulations have been performed to investigate the potential of front surface field (FSF) offered by stack of n-type doped and intrinsic amorphous silicon (a-Si) layers on the front surface of IBC-HJ solar cells. Simulations results clearly indicate that the electric field of FSF should be strong enough to repel minority carries and cumulate major carriers near the front surface. However, the over-strong electric field tends to drive electrons into a-Si layer, leading to severe recombination loss. The n-type doped amorphous silicon (n-a-Si) layer has been optimized in terms of doping level and thickness. The optimized intrinsic amorphous silicon (i-a-Si) layer should be as thin as possible with an energy band gap ( ) larger than 1.4 eV. In addition, the simulations concerning interface defects strongly suggest that FSF is essential when the front surface is not passivated perfectly. Without FSF, the IBC-HJ solar cells may become more sensitive to interface defect density.

关键词： amorphous silicon     front surface field     simulations     interdigitated back contact-heterojunction solar cells    

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乘坐21 世纪40 年代的高铁旅行而归

Ignacio Barron

《工程（英文）》 2016年 第2卷 第3期   页码 292-293 doi: 10.1016/J.ENG.2016.03.020

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我国后端电子制造装备及其关键零部件发展研究

陈新 ,陈云 ,陈桪 ,吴小节

《中国工程科学》 2022年 第24卷 第4期   页码 74-84 doi: 10.15302/J-SSCAE-2022.04.008

摘要： Engineering project “Empirical Research on Deficiencies in Key Foundation and Industrial Chain for Back-End

关键词： 后端电子制造     供应链重塑     电子制造装备     多芯片器件集成     企业案例    

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标题 作者 时间 类型 操作

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

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

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

Dmitry KUKLIN

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

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

综论大坝原型反分析及其应用

顾冲时,吴中如

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

hexavalent chromium using a porous titanium flow-through electrode and intelligent prediction based on a back

期刊论文

Day-ahead electricity price forecasting using back propagation neural networks and weighted least square

S. Surender REDDY,Chan-Mook JUNG,Ko Jun SEOG

期刊论文

of using amorphous silicon stack as front heterojunction structure on performance of interdigitated back

Rui JIA,Ke TAO,Qiang LI,Xiaowan DAI,Hengchao SUN,Yun SUN,Zhi JIN,Xinyu LIU

期刊论文

乘坐21 世纪40 年代的高铁旅行而归

Ignacio Barron

期刊论文

我国后端电子制造装备及其关键零部件发展研究

陈新 ,陈云 ,陈桪 ,吴小节

期刊论文