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Dynamic characteristics analysis of active constrained layer damping plate with various boundary conditions

Jing LU, Yu XIANG, Qiao NI

《机械工程前沿（英文）》 2011年第6卷第4期页码 449-455 doi: 10.1007/s11465-011-0240-0

摘要：

Considering the direct and converse piezoelectric effect, expressions of piezoelectric membrane internal forces in the piezoelectric constrained layer were given. The control equations of the piezoelectric constrained layer and host plate were obtained in according with the thin plate theory. Based on the layer wised principle, the integrated first order differential equation of an active constrained layer damping (ACLD) plate was derived for the simply supported boundary condition. Then, this method was expanded to the ACLD plate with cantilever boundary condition by virtue of geometric analogy method. Employing the extended homogeneous capacity precision integration approach, a high precision semi-analytical method was proposed to analyze the dynamic characteristics of the ACLD plate with various boundary conditions. The comparison with the literature results has verified the accuracy and effectiveness of the present method.

关键词： active constrained layer damping (ACLD) plate dynamic characteristics semi-analytical method extended homogeneous capacity precision integration approach

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Foundations bearing capacity subjected to seepage by the kinematic approach of the limit analysis

Mehdi VEISKARAMI, Ghasem HABIBAGAHI

《结构与土木工程前沿（英文）》 2013年第7卷第4期页码 446-455 doi: 10.1007/s11709-013-0227-5

摘要： An estimate of the ultimate load on foundations on soil layers subject to groundwater flow has been presented. The kinematic approach of the limit analysis was employed to find the upper-bound limit of the bearing capacity. Both smooth and rough base strip foundations were considered associated with different collapse patterns. Presence of the groundwater flow leads to a non-symmetric collapse pattern, i.e., a weak side and a strong side in two-sided collapse patterns, depending on the direction of the flow. It was found that the bearing capacity has a decreasing trend with increase in the groundwater flow gradient and hence, a reduction factor has been introduced to the third term in the bearing capacity equation as a function of the flow gradient.

关键词： foundation bearing capacity limit analysis numerical computation plasticity seepage

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高成本效益的分布式可再生能源并网方法 Article

Till Luhmann,Enno Wieben,Riccardo Treydel,Michael Stadler,Thomas Kumm

《工程（英文）》 2015年第1卷第4期页码 447-452 doi: 10.15302/J-ENG-2015099

摘要：

本文介绍了一种配电网容量管理的具体方法。经模拟发现，通过将每台发电机的全年发电量削减最多5%，可使配电网的并网容量翻倍。本文同时还介绍了为验证此方法而在德国北部的农村配电网进行的现场测试的设置和初步结果。

关键词：电网容量管理 5% 法可再生能源电力分配网

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Uncertainty propagation analysis by an extended sparse grid technique

X. Y. JIA, C. JIANG, C. M. FU, B. Y. NI, C. S. WANG, M. H. PING

《机械工程前沿（英文）》 2019年第14卷第1期页码 33-46 doi: 10.1007/s11465-018-0514-x

摘要： In this paper, an uncertainty propagation analysis method is developed based on an extended sparse grid technique and maximum entropy principle, aiming at improving the solving accuracy of the high-order moments and hence the fitting accuracy of the probability density function (PDF) of the system response. The proposed method incorporates the extended Gauss integration into the uncertainty propagation analysis. Moreover, assisted by the Rosenblatt transformation, the various types of extended integration points are transformed into the extended Gauss-Hermite integration points, which makes the method suitable for any type of continuous distribution. Subsequently, within the sparse grid numerical integration framework, the statistical moments of the system response are obtained based on the transformed points. Furthermore, based on the maximum entropy principle, the obtained first four-order statistical moments are used to fit the PDF of the system response. Finally, three numerical examples are investigated to demonstrate the effectiveness of the proposed method, which includes two mathematical problems with explicit expressions and an engineering application with a black-box model.

关键词： uncertainty propagation analysis extended sparse grid maximum entropy principle extended Gauss integration Rosenblatt transformation high-order moments analysis

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Determination of the scheme of precision grinding compensation on the radome

GUO Dongming, LIU Minjing, ZHANG Chunbo, SHENG Xianjun, SUN Yuwen

《机械工程前沿（英文）》 2007年第2卷第3期页码 263-266 doi: 10.1007/s11465-007-0045-3

摘要： The radome, which is often used to house airborne scanning radar antennas, causes a large boresight error and boresight error slope of the radar antenna. One way to decrease the boresight error induced by the radome is to modify its geometric thickness. Determining the grinding scheme from the boresight error performance is the most important problem to be solved. A typical inverse problem about electromagnetic fields is solving the precise grinding compensation area and allowance according to the antenna aperture distribution and the radome s boresight error performance, which could hardly be solved by a purely mathematical method. An effective approach combining theoretical analysis and mathematical calculations with experimental measurement is presented in this paper to determine the grinding area and allowance for compensating the boresight error performance of the radome. By comparing the calculated and measured data of the boresight error and the boresight error slope before and after grinding, it is shown that this method is simple and practical and can be used for many kinds of radomes.

关键词： mathematical effective approach experimental measurement antenna electromagnetic

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A new and best approach for early detection of rotor and stator faults in induction motors coupled to

Abderrahim ALLAL,Boukhemis CHETATE

《能源前沿（英文）》 2016年第10卷第2期页码 176-191 doi: 10.1007/s11708-015-0386-2

摘要： Today, induction machines are playing, thanks to their robustness, an important role in world industries. Although they are quite reliable, they have become the target of various types of defects. Thus, for a long time, many research laboratories have been focusing their works on the theme of diagnosis in order to find the most efficient technique to predict a fault in an early stage and to avoid an unplanned stopping in the chain of production and costs ensuing. In this paper, an approach called Park’s vector product approach (PVPA) was proposed which was endowed with a dominant sensitivity in the case in which there would be rotor or stator faults. To show its high sensitivity, it was compared with the classical methods such as motor current signature analysis (MCSA) and techniques studied in recent publications such as motor square current signature analysis (MSCSA), Park’s vector square modulus (PVSM) and Park-Hilbert (P-H) (PVSM ). The proposed technique was based on three main steps. First, the three-phase currents of the induction motor led to a Park’s vector. Secondly, the proposed PVPA was calculated to show the distinguishing spectral signatures of each default and specific frequencies. Finally, simulation and experimental results were presented to confirm the theoretical assumptions.

关键词： induction motor incipient broken bar extended Park’s vector approach spectral analysis inter-turn short-circuit Hilbert transform

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Heat Integration retrofit analysis—an oil refinery case study by Retrofit Tracing Grid Diagram

Andreja NEMET, Jiří Jaromír KLEMEŠ, Petar Sabev VARBANOV, Valter MANTELLI

《化学科学与工程前沿（英文）》 2015年第9卷第2期页码 163-182 doi: 10.1007/s11705-015-1520-8

摘要： Heat Integration has been established over the last decades as a proven chemical engineering methodology. Two design implementations are often used in the industry: grassroots and retrofit. Although various methods have been developed for retrofit, it still needs more development to ensure simultaneously thermodynamic feasibility and economic viability. In this paper, a novel graphical approach has been developed to facilitate the understanding of the current situation and scope of improvement. The Retrofit Tracing Grid Diagram presents all streams and heat exchangers in temperature scale and the heat exchangers are clearly separated from each other, enabling clear visualisation of the current state. The tool incorporates the previously developed Cross-Pinch Analysis as well as path approach for retrofit. Additionally, the non-vertical heat transfer can be evaluated. The application of the developed tool has been validated on an oil refinery case study. The applicability of the tool is evident as it can reveal additional options for modification that none of the previous methods considered.

关键词： Heat Integration retrofit Pinch Analysis thermodynamic approach oil refinery

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An integrated approach to site-specific management zone delineation

Yuxin MIAO, David J. MULLA, Pierre C. ROBERT

《农业科学与工程前沿（英文）》 2018年第5卷第4期页码 432-441 doi: 10.15302/J-FASE-2018230

摘要：

Dividing fields into a few relatively homogeneous management zones (MZ) is a practical and cost-effective approach to precision agriculture. There are three basic approaches to MZ delineation using soil and/or landscape properties, yield information, and both sources of information. The objective of this study is to propose an integrated approach to delineating site-specific MZ using relative elevation, organic matter, slope, electrical conductivity, yield spatial trend map, and yield temporal stability map (ROSE-YSTTS) and evaluate it against two other approaches using only soil and landscape information (ROSE) or clustering multiple year yield maps (CMYYM). The study was carried out on two no-till corn-soybean rotation fields in eastern Illinois, USA. Two years of nitrogen (N) rate experiments were conducted in Field B to evaluate the delineated MZs for site-specific N management. It was found that in general the ROSE approach was least effective in accounting for crop yield variability (8.0%–9.8%), while the CMYYM approach was least effective in accounting for soil and landscape (8.9%–38.1%), and soil nutrient and pH variability (9.4%–14.5%). The integrated ROSE-YSTTS approach was reasonably effective in accounting for the three sources of variability (38.6%–48.9%, 16.1%–17.3% and 13.2%–18.7% for soil and landscape, nutrient and pH, and yield variability, respectively), being either the best or second best approach. It was also found that the ROSE-YSTTS approach was effective in defining zones with high, medium and low economically optimum N rates. It is concluded that the integrated ROSE-YSTTS approach combining soil, landscape and yield spatial-temporal variability information can overcome the weaknesses of approaches using only soil, landscape or yield information, and is more robust for MZ delineation. It also has the potential for site-specific N management for improved economic returns. More studies are needed to further evaluate their appropriateness for precision N and crop management.

关键词： economically optimum nitrogen rate fuzzy cluster analysis precision nitrogen management site-specific management soil landscape property yield map

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面向2035年复合材料构件精确制造发展战略研究

单忠德,宋文哲,范聪泽,汪俊

《中国工程科学》 2023年第25卷第1期页码 113-120 doi: 10.15302/J-SSCAE-2023.07.002

摘要：

先进复合材料具有高比强度、高比模量、可设计性好等优点，广泛应用于航空航天、轨道交通等领域的装备制造，是工业发达国家战略必争资源；保障和提升先进复合材料的供给能力，突破大型复杂复合材料构件的设计成形、加工装配、检测修复等精确制造技术，对支撑制造强国建设具有重要价值。本文总结了国内外复合材料构件精确制造技术的发展现状及趋势，从高精密数控缠绕、复合材料自动铺放、复合材料预制体成形、纤维复合材料增材制造、高性能碳纤维生产等方面梳理了复合材料构件精确制造的关键技术与装备；结合基本态势研判了制约复合材料制造技术水平提升的“卡脖子”环节，提出了我国复合材料构件制造技术与装备的发展思路与分阶段发展目标。研究建议，组织建设国家级创新机构，设立国家重大专项支持，加强学科建设和人才培养，加强国际技术交流与合作，着力推动重大科学创新和关键技术突破，为国家重大工程和装备应用提供高质量科技支撑。

关键词：复合材料；精确制造；高端装备；结构功能一体化

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高性能零件的性能与几何参数一体化精密加工方法与技术

郭东明

《中国工程科学》 2011年第13卷第10期页码 47-57

摘要：

随着高端装备和产品的不断发展，对装备和产品制造的性能要求也越来越多和越来越高，涌现出一大批高性能指标要求的关键零部件，其加工已由以往的单纯几何形状和尺寸精度要求，跃升为以性能要求为主、性能与几何参数一体化的精密加工要求。这些高性能零件多呈精密复杂曲面、超高精度，以及材料超硬、超脆、超黏等难加工特征，其性能受几何、材料等多因素耦合作用，采用传统工艺进行精密加工制造十分困难，存在废品率高、加工效率低，特别是性能指标难以保证等难题。从高端制造装备业的需求出发，提出并阐明了高性能零件的特点、分类以及数字化可控去除加工方式的内涵，在此基础上指出了四类高性能零件精密加工所涉及的关键问题，并着重介绍了这些问题的研究现状、存在的难点和可行的解决方案，为面向高性能要求的性能与几何参数一体化的加工理论、方法和工艺技术体系的建立提供参考，以解决高性能零件的精密制造难题。

关键词：高性能性能与几何参数一体化精密加工难加工材料复杂曲面

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Capacity analysis for cognitive heterogeneous networks with ideal/non-ideal sensing

Tao HUANG, Ying-lei TENG, Meng-ting LIU, Jiang LIU

《信息与电子工程前沿（英文）》 2015年第16卷第1期页码 1-11 doi: 10.1631/FITEE.1400129

摘要： Due to irregular deployment of small base stations (SBSs), the interference in cognitive heterogeneous networks (CHNs) becomes even more complex; in particular, the uncertainty of spectrum mobility aggravates the interference context. In this case, how to analyze system capacity to obtain a closed-form expression becomes a crucial problem. In this paper we employ stochastic methods to formulate the capacity of CHNs and achieve a closed-form expression. By using discrete-time Markov chains (DTMCs), the spectrum mobility with respect to the arrival and departure of macro base station (MBS) users is modeled. Then an integral method is proposed to derive the interference based on stochastic geometry (SG). Also, the effect of sensing accuracy on network capacity is discussed by concerning false-alarm and miss-detection events. Simulation results are illustrated to show that the proposed capacity analysis method for CHNs can approximate the conventional sum methods without rigorous requirement for channel station information (CSI). Therefore, it turns out to be a feasible and efficient way to capture the network capacity in CHNs.

关键词： Cognitive heterogeneous networks Markov chain Stochastic geometry Homogeneous Poisson point process (HPPP)

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Effect of a less permeable stronger soil layer on the stability of non-homogeneous unsaturated slopes

Nabarun DEY, Aniruddha SENGUPTA

《结构与土木工程前沿（英文）》 2020年第14卷第6期页码 1462-1475 doi: 10.1007/s11709-020-0674-8

摘要： Slope failure occurs due to an increase in the saturation level and a subsequent decrease in matric suction in unsaturated soil. This paper presents the results of a series of centrifuge experiments and numerical analyses on a 55° inclined unsaturated sandy slope with less permeable, stronger silty sand layer inclusion within it. It is observed that a less permeable, stronger silty sand layer in an otherwise homogeneous sandy soil slope hinders the infiltration of water. The water content of the slope just above the stronger layer increases significantly, compared to elsewhere. No shear band is found to initiate in a homogeneous sandy soil slope, whereas for a non-homogeneous slope, they initiate just above the less pervious, stronger layer. A discontinuity of the shear zone is also observed for the case of a non-homogeneous soil slope. The factor of safety of a non-homogeneous, unsaturated soil slope decreases because of the less permeable, stronger layer. It decreases significantly if this less permeable, stronger soil layer is located near the toe of the slope.

关键词： non-homogeneous slope stronger soil layer factor of safety centrifuge model test unsaturated soils

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Lateral-torsional buckling capacity assessment of web opening steel girders by artificial neural networks

Yasser SHARIFI,Sajjad TOHIDI

《结构与土木工程前沿（英文）》 2014年第8卷第2期页码 167-177 doi: 10.1007/s11709-014-0236-z

摘要： Bridge girders exposed to aggressive environmental conditions are subject to time-variant changes in resistance. There is therefore a need for evaluation procedures that produce accurate predictions of the load-carrying capacity and reliability of bridge structures to allow rational decisions to be made about repair, rehabilitation and expected life-cycle costs. This study deals with the stability of damaged steel I-beams with web opening subjected to bending loads. A three-dimensional (3D) finite element (FE) model using ABAQUS for the elastic flexural torsional analysis of I-beams has been used to assess the effect of web opening on the lateral buckling moment capacity. Artificial neural network (ANN) approach has been also employed to derive empirical formulae for predicting the lateral-torsional buckling moment capacity of deteriorated steel I-beams with different sizes of rectangular web opening using obtained FE results. It is found out that the proposed formulae can accurately predict residual lateral buckling capacities of doubly-symmetric steel I-beams with rectangular web opening. Hence, the results of this study can be used for better prediction of buckling life of web opening of steel beams by practice engineers.

关键词： steel I-beams lateral-torsional buckling finite element (FE) method artificial neural network (ANN) approach

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Control of homogeneous charge compression ignition combustion in a two-cylinder gasoline direct injection

WANG Zhi, WANG Jianxin, SHUAI Shijin, MA Qingjun, TIAN Guohong

《能源前沿（英文）》 2007年第1卷第3期页码 311-315 doi: 10.1007/s11708-007-0045-3

摘要： Homogeneous charge compression ignition (HCCI) has challenges in ignition timing control, combustion rate control, and operating range extension. In this paper, HCCI combustion was studied in a two-cylinder gasoline direct injection (GDI) engine with negative valve overlap (NVO). A two-stage gasoline direct injection strategy combined with negative valve overlap was used to control mixture formation and combustion. The gasoline engine could be operated in HCCI combustion mode at a speed range of 800–2 200 r/min and load, indicated mean effective pressure (IMEP) range of 0.1–0.53 MPa. The engine fuel consumption is below 240 g/(kW

关键词： Homogeneous control combustion consumption extension

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An approach for evaluating fire resistance of high strength Q460 steel columns

Wei-Yong WANG, Guo-Qiang LI, Bao-lin YU

《结构与土木工程前沿（英文）》 2014年第8卷第1期页码 26-35 doi: 10.1007/s11709-014-0239-9

摘要： To develop a methodology for evaluating fire resistance of high strength Q460 steel columns, the load bearing capacity of high strength Q460 steel columns is investigated. The current approach of evaluating load bearing capacity of mild steel columns at room temperature is extended to high strength Q460 steel columns with due consideration to high temperature properties of high strength Q460 steel. The critical temperature of high strength Q460 steel column is presented and compared with mild steel columns. The proposed approach was validated by comparing the predicted load capacity with that evaluated through finite element analysis and test results. In addition, parametric studies were carried out by employing the proposed approach to study the effect of residual stress and geometrical imperfections. Results from parametric studies show that, only for a long column (slenderness higher than 75), the magnitude and distribution mode of residual stress have little influence on ultimate load bearing capacity of high strength Q460 steel columns, but the geometrical imperfections have significant influence on any columns. At a certain slenderness ratio, the stability factor first decreases and then increases with temperature rise.

关键词： high strength Q460 steel load bearing capacity temperature