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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    

Radiative properties of materials with surface scattering or volume scattering: A review

Qunzhi ZHU, Hyunjin LEE, Zhuomin M. HANG

《能源前沿(英文)》 2009年 第3卷 第1期   页码 60-79 doi: 10.1007/s11708-009-0011-3

摘要: Radiative properties of rough surfaces, particulate media and porous materials are important in thermal engineerit transfer between surfaces and volume elements in participating media, as well as for accurate radiometric temperature measurements. In this paper, recent research on scattering of thermal radiation by rough surfaces, fibrous insulation, soot, aerogel, biological materials, and polytetrafluoroethylene (PTFE) was reviewed. Both theoretical modeling and experimental investigation are discussed. Rigorous solutions and approximation methods for surface scattering and volume scattering are described. The approach of using measured surface roughness statistics in Monte Carlo simulations to predict radiative properties of rough surfaces is emphasized. The effects of various parameters on the radiative properties of particulate media and porous materials are summarized.

关键词: aerogel     fiber     particle scattering     radiative properties     soot     surface roughness    

柱形地形上单浮体的辐射和散射问题

吴必军,郑永红,游亚戈,孙晓燕,陈勇

《中国工程科学》 2004年 第6卷 第2期   页码 48-55

摘要:

在有限水深、同轴但半径大于或等于浮体半径的圆柱体障碍物地形条件下,基于特征函数展开法,推导了垂直放置的圆柱形浮体由于波的辐射和散射作用所表现的动力学和运动学特征表达式,涉及浮体做垂荡、横荡和横摇运动所产生的辐射势,以及在入射波的作用下,由于浮体固定不动而产生的散射势,并推导了激励力、附加质量和阻尼系数表达式。采用与同轴、同半径圆柱体障碍物地形上单浮体水动力学特性相比的方式和激励力计算两种方法验证了推导的表达式,最后分析了障碍物几何尺寸对浮体水动力学特性的特有影响。

关键词: 解析方法     速度势     波浪力    

Effect of light scattering on the performance of a direct absorption solar collector

Kwang Hyun WON, Bong Jae LEE

《能源前沿(英文)》 2018年 第12卷 第1期   页码 169-177 doi: 10.1007/s11708-018-0527-5

摘要: Recently, a solar thermal collector often employs nanoparticle suspension to absorb the solar radiation directly by a working fluid as well as to enhance its thermal performance. The collector efficiency of a direct absorption solar collector (DASC) is very sensitive to optical properties of the working fluid, such as absorption and scattering coefficients. Most of the existing studies have neglected particle scattering by assuming that the size of nanoparticle suspension is much smaller than the wavelength of solar radiation (i.e., Rayleigh scattering is applicable). If the nanoparticle suspension is made of metal, however, the scattering cross-section of metallic nanoparticles could be comparable to their absorption cross-section depending on the particle size, especially when the localized surface plasmon (LSP) is excited. Therefore, for the DASC utilizing a plasmonic nanofluid supporting the LSP, light scattering from metallic particle suspension must be taken into account in the thermal analysis. The present study investigates the scattering effect on the thermal performance of the DASC employing plasmonic nanofluid as a working fluid. In the analysis, the Monte Carlo method is employed to numerically solve the radiative transfer equation considering the volume scattering inside the nanofluid. It is found that the light scattering can improve the collector performance if the scattering coefficient of nanofluid is carefully engineered depending on its value of the absorption coefficient.

关键词: direct absorption solar collector     plasmonic nanofluid     light scattering    

火灾烟雾颗粒的光学散射特性研究

疏学明,方俊,邵荃,袁宏永

《中国工程科学》 2005年 第7卷 第1期   页码 45-49

摘要:

从理论和实验两个方面研究了几种常见的燃烧烟雾在不同波长激光下的散射特性。从Mie散射理论出发,比较几种Mie散射算法的优缺点,采用一种改进的连分式算法对火灾烟雾颗粒的散射光强分布进行计算,得出不同粒径大小和波长下光强分布图。结合理论计算,设计一套实验装置,测量并计算在不同角度下3种烟雾颗粒和面粉气溶胶散射光的相对光强比,实验测量值与理论计算值吻合较好。研究结果表明不同种类烟雾散射光相对光强比互不相同,火灾烟雾与非烟雾气溶胶差距较大,从而表明散射光相对光强比是区分不同烟雾特定的物性参数,为火灾烟雾探测技术发展提供理论依据。

关键词: 火灾烟雾     Mie散射     算法     相对光强比    

Airline planning and scheduling: Models and solution methodologies

Lei ZHOU, Zhe LIANG, Chun-An CHOU, Wanpracha Art CHAOVALITWONGSE

《工程管理前沿(英文)》 2020年 第7卷 第1期   页码 1-26 doi: 10.1007/s42524-020-0093-5

摘要: The airline industry is a representative industry with high cost and low profitability. Therefore, airlines should carefully plan their schedules to ensure that overall profit is maximized. We review the literature on airline planning and scheduling and focus on mathematical formulations and solution methodologies. Our research framework is anchored on three major problems in the airline scheduling, namely, fleet assignment, aircraft routing, and crew scheduling. General formulation, widely used solution approaches, and important extensions are presented for each problem and integrated problems. We conclude the review by identifying promising areas for further research.

关键词: airline planning     fleet assignment problem     aircraft routing problem     crew pairing problem     crew rostering problem     crew scheduling problem     integrated planning    

Discussion on Problem-Based Engineering Management System

Qiao Xiang

《工程管理前沿(英文)》 2015年 第2卷 第3期   页码 249-260 doi: 10.15302/J-FEM-2015054

摘要: The paper puts forward the idea of problem-based engineering management, expounds its connotation and guiding ideology and moreover, substantially demonstrates its practical significance in the engineering management system for the maintenance of Chinese military aircraft engines.

关键词: problem     engineering management     system    

基于去散射与边缘增强算法的水下图像复原 Research Papers

Pan-wang PAN, Fei YUAN, En CHENG

《信息与电子工程前沿(英文)》 2019年 第20卷 第6期   页码 862-871 doi: 10.1631/FITEE.1700744

摘要: 对色差严重和边缘模糊的水下图像需进行复原。一般分两步:去散射和边缘增强。首先,提出一种用于水下图像去散射的多尺度迭代框架。利用卷积神经网络估计传输图,再用自适应双边滤波器改进传输图估计结果。由于无可用数据集训练网络,收集包含2000个水下图像的数据集以获得合成数据。其次,采用白平衡算法消除水下图像的色偏。最后将图像转换到特殊变换域,使用非下采样轮廓波变换对边缘去噪和增强。结果表明:该方法主、客观质量均明显优于现有方法。

关键词: 图像散射;边缘增强;卷积神经网络;非下采样轮廓波变换    

子波分析在声辐射和声散射中的应用

文立华,任兴民

《中国工程科学》 2002年 第4卷 第8期   页码 63-68

摘要:

文章提出将子波分析用于求解声学中的边界积分方程,能提高现有边界元方法解决工程问题的能力。在子波分析于声辐射和声散射的应用研究中,提出了把积分核函数用级数展开,建立频率响应函数计算的频率迭代技术,大大提高了频率响应函数的计算效率。讨论了子波分析在声学工程数值计算中的研究前景。

关键词: 子波分析     声辐射和散射     结构声耦合     频率响应函数    

A solution to stochastic unit commitment problem for a wind-thermal system coordination

B. SARAVANAN,Shreya MISHRA,Debrupa NAG

《能源前沿(英文)》 2014年 第8卷 第2期   页码 192-200 doi: 10.1007/s11708-014-0306-x

摘要: Unit commitment (UC) problem is one of the most important decision making problems in power system. In this paper the UC problem is solved by considering it as a real time problem by adding stochasticity in the generation side because of wind-thermal co-ordination system as well as stochasticity in the load side by incorporating the randomness of the load. The most important issue that needs to be addressed is the achievement of an economic unit commitment solution after solving UC as a real time problem. This paper proposes a hybrid approach to solve the stochastic unit commitment problem considering the volatile nature of wind and formulating the UC problem as a chance constrained problem in which the load is met with high probability over the entire time period.

关键词: unit commitment (UC)     randomness     wind generation     univariate     chance constrained    

Transient analysis of thermoelastic contact problem of disk brakes

Ali BELHOCINE, Mostefa BOUCHETARA

《机械工程前沿(英文)》 2013年 第8卷 第2期   页码 150-159 doi: 10.1007/s11465-013-0266-6

摘要:

The main purpose of this study is to analyze the thermomechanical behavior of the dry contact between the brake disk and pads during the braking phase. The simulation strategy is based on computer code ANSYS11. The modeling of transient temperature in the disk is actually used to identify the factor of geometric design of the disk to install the ventilation system in vehicles. The thermal-structural analysis is then used with coupling to determine the deformation established and the Von Mises stresses in the disk, the contact pressure distribution in pads. The results are satisfactory compared to those found in the literature.

关键词: brake disks     heat flux     heat-transfer coefficient     Von Mises stress     contact pressure    

Solving unit commitment problem using a novel version of harmony search algorithm

Roozbeh MORSALI,Tohid JAFARI,Amirhossein GHODS,Mohammad KARIMI

《能源前沿(英文)》 2014年 第8卷 第3期   页码 297-304 doi: 10.1007/s11708-014-0309-7

摘要: In this context, a novel structure was proposed for improving harmony search (HS) algorithm to solve the unit comment (UC) problem. The HS algorithm obtained optimal solution for defined objective function by improvising, updating and checking operators. In the proposed improved self-adaptive HS (SGHS) algorithm, two important control parameters were adjusted to reach better solution from the simple HS algorithm. The objective function of this study consisted of operation, start-up and shut-down costs. To confirm the effectiveness, the SGHS algorithm was tested on systems with 10, 20, 40 and 60 generating units, and the obtained results were compared with those of the simple HS algorithm and other related works.

关键词: generation scheduling     harmony search (HS) algorithm     intelligent technique     unit commitment    

A solution to the unit commitment problem—a review

B. SARAVANAN, Siddharth DAS, Surbhi SIKRI, D. P. KOTHARI

《能源前沿(英文)》 2013年 第7卷 第2期   页码 223-236 doi: 10.1007/s11708-013-0240-3

摘要: Unit commitment (UC) is an optimization problem used to determine the operation schedule of the generating units at every hour interval with varying loads under different constraints and environments. Many algorithms have been invented in the past five decades for optimization of the UC problem, but still researchers are working in this field to find new hybrid algorithms to make the problem more realistic. The importance of UC is increasing with the constantly varying demands. Therefore, there is an urgent need in the power sector to keep track of the latest methodologies to further optimize the working criterions of the generating units. This paper focuses on providing a clear review of the latest techniques employed in optimizing UC problems for both stochastic and deterministic loads, which has been acquired from many peer reviewed published papers. It has been divided into many sections which include various constraints based on profit, security, emission and time. It emphasizes not only on deregulated and regulated environments but also on renewable energy and distributed generating systems. In terms of contributions, the detailed analysis of all the UC algorithms has been discussed for the benefit of new researchers interested in working in this field.

关键词: unit commitment (UC)     optimization     deterministic load     stochastic load     evolutionary programming (EP)     hybrid    

Hydrocele of the canal of Nuck — an old problem revisited

null

《医学前沿(英文)》 2013年 第7卷 第4期   页码 517-519 doi: 10.1007/s11684-013-0300-4

摘要:

Herein the authors describe the case of a young woman presenting with a tender lump in her groin. Clinically the differential was of either a reactive lymph node or a femoral hernia. Ultrasound scan was urgently arranged and showed a cystic lesion. Surgical exploration was carried out and revealed this to be a hydrocele of the canal of Nuck. This was excised and the patient’s symptoms resolved and she was discharged home the following day. We explore the embryology, pathophysiology and management of this rare entity.

关键词: canal of Nuck     hernia     embryology    

Molecular diffusion in ternary poly(vinyl alcohol) solutions

《化学科学与工程前沿(英文)》 2022年 第16卷 第6期   页码 1003-1016 doi: 10.1007/s11705-021-2121-3

摘要: The diffusion kinetics of a molecular probe—rhodamine B—in ternary aqueous solutions containing poly(vinyl alcohol), glycerol, and surfactants was investigated using fluorescence correlation spectroscopy and dynamic light scattering. We show that the diffusion characteristics of rhodamine B in such complex systems is determined by a synergistic effect of molecular crowding and intermolecular interactions between chemical species. The presence of glycerol has no noticeable impact on rhodamine B diffusion at low concentration, but significantly slows down the diffusion of rhodamine B above 3.9% (w/v) due to a dominating steric inhibition effect. Furthermore, introducing surfactants (cationic/nonionic/anionic) to the system results in a decreased diffusion coefficient of the molecular probe. In solutions containing nonionic surfactant, this can be explained by an increased crowding effect. For ternary poly(vinyl alcohol) solutions containing cationic or anionic surfactant, surfactant–polymer and surfactant–rhodamine B interactions alongside the crowding effect of the molecules slow down the overall diffusivity of rhodamine B. The results advance our insight of molecular migration in a broad range of industrial complex formulations that incorporate multiple compounds, and highlight the importance of selecting the appropriate additives and surfactants in formulated products.

关键词: fluorescence correlation spectroscopy     poly(vinyl alcohol)     anomalous diffusion     crowding effects     dynamic light scattering     binding effects     rhodamine B    

标题 作者 时间 类型 操作

Shape reconstruction of parallelogram flaw

ZHENG Gangfeng, WU Bin, HE Cunfu

期刊论文

Radiative properties of materials with surface scattering or volume scattering: A review

Qunzhi ZHU, Hyunjin LEE, Zhuomin M. HANG

期刊论文

柱形地形上单浮体的辐射和散射问题

吴必军,郑永红,游亚戈,孙晓燕,陈勇

期刊论文

Effect of light scattering on the performance of a direct absorption solar collector

Kwang Hyun WON, Bong Jae LEE

期刊论文

火灾烟雾颗粒的光学散射特性研究

疏学明,方俊,邵荃,袁宏永

期刊论文

Airline planning and scheduling: Models and solution methodologies

Lei ZHOU, Zhe LIANG, Chun-An CHOU, Wanpracha Art CHAOVALITWONGSE

期刊论文

Discussion on Problem-Based Engineering Management System

Qiao Xiang

期刊论文

基于去散射与边缘增强算法的水下图像复原

Pan-wang PAN, Fei YUAN, En CHENG

期刊论文

子波分析在声辐射和声散射中的应用

文立华,任兴民

期刊论文

A solution to stochastic unit commitment problem for a wind-thermal system coordination

B. SARAVANAN,Shreya MISHRA,Debrupa NAG

期刊论文

Transient analysis of thermoelastic contact problem of disk brakes

Ali BELHOCINE, Mostefa BOUCHETARA

期刊论文

Solving unit commitment problem using a novel version of harmony search algorithm

Roozbeh MORSALI,Tohid JAFARI,Amirhossein GHODS,Mohammad KARIMI

期刊论文

A solution to the unit commitment problem—a review

B. SARAVANAN, Siddharth DAS, Surbhi SIKRI, D. P. KOTHARI

期刊论文

Hydrocele of the canal of Nuck — an old problem revisited

null

期刊论文

Molecular diffusion in ternary poly(vinyl alcohol) solutions

期刊论文