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Analysis and design of pulse frequency modulation dielectric barrier discharge for low power applications

Tang-tang GUO,Xing-liang LIU,Shi-qiang HAO,Chi ZHANG,Xiang-ning HE

《信息与电子工程前沿（英文）》 2015年 第16卷 第3期   页码 249-258 doi: 10.1631/FITEE.1400185

摘要： For low power dielectric barrier discharge (DBD) used in small-size material treatment or portable devices, highstep transformer parasitic capacitance greatly influences the performance of the resonant converter as it is of the same order of magnitude as the equivalent capacitance of DBD load. In this paper, steady-state analysis of the low power DBD is presented, considering the inevitable parasitic capacitance of the high-step transformer. The rectifier-compensated first harmonic approximation (RCFHA) is applied to linearize the equivalent load circuit of DBD at low frequency and the derived expressions are accurate and convenient for the analysis and design of the power supply. Based on the proposed linear equivalent load circuit, the influence of transformer parasitic capacitance on the key parameters, including the frequency range and the applied electrode voltage, is discussed when the power is regulated with pulse frequency modulation (PFM). Also, a design procedure is presented based on the derived expressions. A prototype is constructed according to the design results and the accuracy of the design is verified by experimental results.

关键词： Dielectric barrier discharge     Rectifier-compensated first harmonic approximation     Parasitic capacitance     Power converter design    

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安全性第一准则下的组合贷款模型

唐万生,严维真,宁玉富

《中国工程科学》 2007年 第9卷 第11期   页码 137-141

摘要：

提出了一种在概率准则意义下的组合贷款模型，并设计了基于随机模拟的混合优化算法进行求解。 该算法突破了各种贷款收益率必须服从正态分布的假定，可对贷款收益率是任意分布形式的模型进行求解。 经数值仿真，验证了算法的可行性。

关键词： 组合贷款     安全性第一准则     随机模拟     遗传算法     同步扰动随机逼近    

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Evaluation of the harmonic scalpel in open surgery for abdominal aortic aneurysm

null

《医学前沿（英文）》 2012年 第6卷 第1期   页码 85-88 doi: 10.1007/s11684-012-0174-x

摘要：

The harmonic scalpel is a hemostatic device primarily designed for use in laparoscopic surgery. During the last few years, many surgeons have begun to use the harmonic scalpel in open surgery. Several papers have cited the benefits of the device compared with conventional knot-tying techniques; however, no evidence showing the advantages of using the harmonic scalpel in complicated abdominal aortic aneurysm (AAA) surgery has been presented. The aim of the present study is to determine the value of the harmonic scalpel in open operation for AAA. A total of 153 patients who underwent open surgery for AAA at the Department of Vascular Surgery of Guangdong General Hospital, China between January 2001 and December 2010, were retrospectively analyzed. Open surgery performed with the harmonic scalpel on 105 patients was compared with open operation using conventional knot-tying techniques on 48 patients. The operative time, intraoperative blood loss, total postoperative drainage fluid volumes, hospital stay, and postoperative complications between the two groups were compared. The harmonic scalpel group was associated with a shorter operation time (113.2±23.6 min vs. 232.1±39.2 min, P<0.01) and lower intraoperative blood loss (126.1±96.6 ml vs. 592.1±207.2 ml, P<0.01). Postoperative drainage fluid volumes were greater in the conventional surgery group than in the harmonic scalpel group (702.1±192.8 ml vs. 198.5±97.4 ml, P<0.01). The hospital stay was shorter for the harmonic scalpel group than for the conventional surgery group (10.7±3.3 d vs. 16.5±4.7 d, P<0.05). No differences between the postoperative complications or hospital mortality of the two groups were found. The harmonic scalpel is a safe and minimally invasive tool in open surgery for AAA and is associated with shorter operative time, shorter hospital stay, and lower intraoperative blood loss and postoperative drainage fluid volumes compared with conventional knot-tying techniques.

关键词： abdominal aortic aneurysm     harmonic scalpel     minimally invasive    

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Robust switched fractional controller for performance improvement of single phase active power filter under unbalanced conditions

H. AFGHOUL,F. KRIM,D. CHIKOUCHE,A. BEDDAR

《能源前沿（英文）》 2016年 第10卷 第2期   页码 203-212 doi: 10.1007/s11708-015-0381-7

摘要： A novel controller is proposed to regulate the DC-link voltage of a single phase active power filter (SPAPF). The proposed switched fractional controller (SFC) consists of a conventional PI controller, a fractional order PI (FO-PI) controller and a decision maker that switches between them. Commonly, the conventional PI controller is used in regulation loops due to its advantages in steady-state but it is limited in transient state. On the other hand, the FO-PI controller overcomes these drawbacks but it causes dramatic degradation in control performances in steady-state because of the fractional calculus theory and the approximation method used to implement this kind of controller. Thus, the purpose of this paper is to switch to the PI controller in steady-state to obtain the best power quality and to switch to the FO-PI controller when external disturbances are detected to guarantee a fast transient state. To investigate the efficiency and accuracy of the SFC considering all robustness tests, an experimental setup has been established. The results of the SFC fulfill the requirements, confirm its high performances in steady and transient states and demonstrate its feasibility and effectiveness. The experiment results have satisfied the limit specified by the IEEE harmonic standard 519.

关键词： conventional PI controller     fractional calculus (FC)     total harmonic distortion (THD)     Oustaloup continuous approximation (OCA)     single phase active power filter (SPAPF)    

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Position-varying surface roughness prediction method considering compensated acceleration in milling

《机械工程前沿（英文）》 2021年 第16卷 第4期   页码 855-867 doi: 10.1007/s11465-021-0649-z

摘要： Machined surface roughness will affect parts’ service performance. Thus, predicting it in the machining is important to avoid rejects. Surface roughness will be affected by system position dependent vibration even under constant parameter with certain toolpath processing in the finishing. Aiming at surface roughness prediction in the machining process, this paper proposes a position-varying surface roughness prediction method based on compensated acceleration by using regression analysis. To reduce the stochastic error of measuring the machined surface profile height, the surface area is repeatedly measured three times, and Pauta criterion is adopted to eliminate abnormal points. The actual vibration state at any processing position is obtained through the single-point monitoring acceleration compensation model. Seven acceleration features are extracted, and valley, which has the highest R-square proving the effectiveness of the filtering features, is selected as the input of the prediction model by mutual information coefficients. Finally, by comparing the measured and predicted surface roughness curves, they have the same trends, with the average error of 16.28% and the minimum error of 0.16%. Moreover, the prediction curve matches and agrees well with the actual surface state, which verifies the accuracy and reliability of the model.

关键词： surface roughness prediction     compensated acceleration     milling     thin-walled workpiece    

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An investigation into the vibration of harmonic drive systems

M. Masoumi, H. Alimohammadi

《机械工程前沿（英文）》 2013年 第8卷 第4期   页码 409-419 doi: 10.1007/s11465-013-0275-5

摘要：

Harmonic drive systems are precise and specific transmission gear systems which are beneficial in terms of the high transmission ratio and almost zero backlash. These inherent and spectacular properties result in using this mechanism in robotic and space sciences where the precision and lightwieght play an important role. This paper presents a vibration analysis of harmonic drive systems using the shell theory. Equations of vibration for the flexspline and the circular spline of the system are derived and used to find the natural frequencies for both parts and, moreover, vibration response of the system under the operating condition is calculated. Also, obtained vibration equations are utilized to study the effects of different involved parameters such as the geometry of the flexspline and its gear tooth, eccentricity, and unbalancing on the vibrational behavior of the system.

关键词： harmonic drive system     strain wave gearing mechanism     vibration analysis     natural frequencies    

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Multi-harmonic forced vibration and resonance of simple beams to moving vehicles

《结构与土木工程前沿（英文）》   页码 981-993 doi: 10.1007/s11709-023-0979-5

摘要： This study modeled the moving-vehicle-induced forcing excitation on a single-span prismatic bridge as a multiple frequency-multiplication harmonic load on the modal coordinates of a linear elastic simple Euler–Bernoulli beam, and investigated the forced modal oscillation and resonance behavior of this type of dynamic system. The forced modal responses consist of multiple frequency-multiplication steady-state harmonics and one damped mono-frequency complementary harmonic. The analysis revealed that a moving load induces high-harmonic forced resonance amplification when the moving speed is low. To verify the occurrence of high-harmonic forced resonance, numerical tests were conducted on single-span simple beams based on structural modeling using the finite element method (FEM) and a moving sprung-mass oscillator vehicle model. The forced resonance amplification characteristics of the fundamental mode for beam response estimation are presented with consideration to different end restraint conditions. The results reveal that the high-harmonic forced resonance may be significant for the investigated beams subjected to vehicle loads moving at specific low speeds. For the investigated single-span simple beams, the moving vehicle carriage heaving oscillation modulates the beam modal frequency, but does not induce notable variation of the modal oscillation harmonic structure for the cases that vehicle of small mass moves in low speed.

关键词： forced vibration     linear Euler beam     moving load     harmonic structure     frequency modulation     end restraints    

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Meshing stiffness property and meshing status simulation of harmonic drive under transmission loading

《机械工程前沿（英文）》 2022年 第17卷 第2期 doi: 10.1007/s11465-022-0674-6

摘要： The multitooth meshing state of harmonic drive (HD) is an important basic characteristic of its high transformation precision and high bearing capacity. Meshing force distribution affects the load sharing of the tooth during meshing, and theoretical research remains insufficient at present. To calculate the spatial distributed meshing forces and loading backlashes along the axial direction, an iterative algorithm and finite element model (FEM) is proposed to investigate the meshing state under varied transmission loading. The displacement formulae of meshing point under tangential force are derived according to the torsion of the flexspline cylinder and the bending of the tooth. Based on the relationship of meshing forces and circumferential displacements, meshing forces and loading backlashes in three cross-sections are calculated with the algorithm under gradually increased rotation angles of circular spline, and the results are compared with FEM. Owing to the taper deformation of the cup-shaped flexspline, the smallest initial backlash and the earliest meshing point appear in the front cross-section far from the cup bottom, and then the teeth in the middle cross-section of the tooth rim enter the meshing and carry most of the loading. Theoretical and numerical research show that the flexibility is quite different for varied meshing points and tangential force amplitude because of the change of contact status between the flexspline and the wave generator. The meshing forces and torsional stiffness of the HD are nonlinear with the torsional angle.

关键词： harmonic drive     meshing flexibility matrix     meshing force     loading backlash     flexspline     contact analysis    

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A case study on sample average approximation method for stochastic supply chain network design problem

Yuan WANG, Ruyan SHOU, Loo Hay LEE, Ek Peng CHEW

《工程管理前沿（英文）》 2017年 第4卷 第3期   页码 338-347 doi: 10.15302/J-FEM-2017032

摘要： This study aims to solve a typical long-term strategic decision problem on supply chain network design with consideration to uncertain demands. Existing methods for these problems are either deterministic or limited in scale. We analyze the impact of uncertainty on demand based on actual large data from industrial companies. Deterministic equivalent model with nonanticipativity constraints, branch-and-fix coordination, sample average approximation (SAA) with Bayesian bootstrap, and Latin hypercube sampling were adopted to analyze stochastic demands. A computational study of supply chain network with front-ends in Europe and back-ends in Asia is presented to highlight the importance of stochastic factors in these problems and the efficiency of our proposed solution approach.

关键词： supply chain network     stochastic demand     sampling average approximation     Bayesian bootstrap     Latin hypercube sampling    

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Dynamic analysis of composite beam subjected to harmonic moving load based on the third-order shear deformation

Mohammad Javad REZVANIL, Mohammad Hossein KARGARNOVIN, Davood YOUNESIAN

《机械工程前沿（英文）》 2011年 第6卷 第4期   页码 409-418 doi: 10.1007/s11465-011-0245-8

摘要：

The response of an infinite Timoshenko beam subjected to a harmonic moving load based on the third-order shear deformation theory (TSDT) is studied. The beam is made of laminated composite, and located on a Pasternak viscoelastic foundation. By using the principle of total minimum potential energy, the governing partial differential equations of motion are obtained. The solution is directed to compute the deflection and bending moment distribution along the length of the beam. Also, the effects of two types of composite materials, stiffness and shear layer viscosity coefficients of foundation, velocity and frequency of the moving load over the beam response are studied. In order to demonstrate the accuracy of the present method, the results TSDT are compared with the previously obtained results based on first-order shear deformation theory, with which good agreements are observed.

关键词： timoshenko composite beam     pasternak viscoelastic foundation     third-order shear deformation theory (TSDT)     harmonic moving load    

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China Launched the First Wastewater Resource Recovery Factory in Yixing

《环境科学与工程前沿（英文）》 2022年 第16卷 第1期 doi: 10.1007/s11783-021-1496-1

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Sustainable intensification of agriculture in sub-Saharan Africa: first things first!

Bernard VANLAUWE, Achim DOBERMANN

《农业科学与工程前沿（英文）》 2020年 第7卷 第4期   页码 376-382 doi: 10.15302/J-FASE-2020351

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Effect of harmonic distortion on electric energy meters of different metrological principles

Illia DIAHOVCHENKO, Vitalii VOLOKHIN, Victoria KUROCHKINA, Michal ŠPES, Michal KOSTEREC

《能源前沿（英文）》 2019年 第13卷 第2期   页码 377-385 doi: 10.1007/s11708-018-0571-1

摘要： This paper deals with the errors of electric energy metering devices as a result of distortions in the shape of the curves of voltage and current load. It is shown and proved that the errors in energy measurements depend on the design and the algorithms used in electricity meters. There are three main types of metering devises having different principles: inductive (electro-mechanical), electronic static, and digital electronic (microprocessor). Each of these types has its measuring features. Some devices take into account all the harmonic distortions and the constant component which occur in the network while others measure the power and energy values of the fundamental harmonic only. Such traits lead to the discrepancies in the readings of commercial electric energy meters of different types. Hence, the violations in the measurement system unity occur, and a significant error can be observed in the balance of transmitted/consumed electric energy.

关键词： current     distortion     electric energy meter     harmonics     power quality    

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Shape reconstruction of parallelogram flaw

ZHENG Gangfeng, WU Bin, HE Cunfu

《机械工程前沿（英文）》 2008年 第3卷 第1期   页码 17-22 doi: 10.1007/s11465-008-0015-4

摘要： To reconstruct the shape of the scatterer in elastic media, the authors deduce the Born approximation solution of the two-dimensional scattering problem, which includes the shape factor that embodies all information about the shape of the scatterer. Accordingly, the change in the shape of the scatterer only necessitates the number of the corresponding new shape factors. For a parallelogram void in a long Al rod, its shape factor can be obtained. In view of the definition of a characteristic function, the shape factor has a corresponding integral representation. Obviously, the shape factor can be considered as a Fourier transform of the characteristic function, which is reconstructed from the inverse Fourier transform. The integral equation is considered as the basic equation to reconstruct the shape of the scatterer. The identification of the geometrical character of a flaw is then given by the two dimensional inverse Born approximation in a low-frequency range. For the parallelogram void, a theoretical calculating identification is performed. At the same time, the numerical results are obtained by the finite element method.

关键词： approximation     scatterer     scattering problem     information     inverse    

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广义近似空间与粗糙分类代数

刘永红

《中国工程科学》 2006年 第8卷 第3期   页码 39-48

摘要：

提出了广义近似空间、粗近似公理、干扰集公理、粗糙集的分类原则、粗选原则、不确定偶集原则、精选原则、对策分类、量子逻辑分类、bit量子对称分类、不可比集、bit空间集、协议关系、粗糙集函数、粗糙分类代数和粗糙单代数等基本概念，并提出了一个猜想；展示了一些新观点；基于协议关系构造了粗糙商代数和粗糙子代数，给出了回避-归并算法及算例。

关键词： 广义近似空间     粗糙集     粗糙分类代数     协议关系     粗糙单代数     粗糙商代数     粗糙子代数    

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标题 作者 时间 类型 操作

Analysis and design of pulse frequency modulation dielectric barrier discharge for low power applications

Tang-tang GUO,Xing-liang LIU,Shi-qiang HAO,Chi ZHANG,Xiang-ning HE

期刊论文

安全性第一准则下的组合贷款模型

唐万生,严维真,宁玉富

期刊论文

Evaluation of the harmonic scalpel in open surgery for abdominal aortic aneurysm

null

期刊论文

Robust switched fractional controller for performance improvement of single phase active power filter under unbalanced conditions

H. AFGHOUL,F. KRIM,D. CHIKOUCHE,A. BEDDAR

期刊论文

Position-varying surface roughness prediction method considering compensated acceleration in milling

期刊论文

An investigation into the vibration of harmonic drive systems

M. Masoumi, H. Alimohammadi

期刊论文

Multi-harmonic forced vibration and resonance of simple beams to moving vehicles

期刊论文

Meshing stiffness property and meshing status simulation of harmonic drive under transmission loading

期刊论文

A case study on sample average approximation method for stochastic supply chain network design problem

Yuan WANG, Ruyan SHOU, Loo Hay LEE, Ek Peng CHEW

期刊论文

Dynamic analysis of composite beam subjected to harmonic moving load based on the third-order shear deformation

Mohammad Javad REZVANIL, Mohammad Hossein KARGARNOVIN, Davood YOUNESIAN

期刊论文

China Launched the First Wastewater Resource Recovery Factory in Yixing

期刊论文

Sustainable intensification of agriculture in sub-Saharan Africa: first things first!

Bernard VANLAUWE, Achim DOBERMANN

期刊论文

Effect of harmonic distortion on electric energy meters of different metrological principles

Illia DIAHOVCHENKO, Vitalii VOLOKHIN, Victoria KUROCHKINA, Michal ŠPES, Michal KOSTEREC

期刊论文

Shape reconstruction of parallelogram flaw

ZHENG Gangfeng, WU Bin, HE Cunfu

期刊论文

广义近似空间与粗糙分类代数

刘永红

期刊论文