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Approximation of structural damping and input excitation force

Mohammad SALAVATI

《结构与土木工程前沿（英文）》 2017年 第11卷 第2期   页码 244-254 doi: 10.1007/s11709-016-0371-9

摘要： Structural dynamic characteristics are the most significant parameters that play a decisive role in structural damage assessment. The more sensitive parameter to the damage is the damping behavior of the structure. The complexity of structural damping mechanisms has made this parameter to be one of the ongoing research topics. Despite all the difficulties in the modeling of damping, there are some approaches like as linear and nonlinear models which are described as the energy dissipation throughout viscous, material or structural hysteretic and frictional damping mechanisms. In the presence of a mathematical model of the damping mechanisms, it is possible to estimate the damping ratio from the theoretical comparison of the damped and un-damped systems. On the other hand, solving the inverse problem of the input force estimation and its distribution to each SDOFs, from the measured structural responses plays an important role in structural identification process. In this paper model-based damping approximation method and a model-less structural input estimation are considered. The effectiveness of proposed methods has been carried out through analytical and numerical simulation of the lumped mass system and the results are compared with reference data. Consequently, high convergence of the comparison results illustrates the satisfactory of proposed approximation methods.

关键词： structural modal parameters     damping identification method     input excitation force identification     Inverse problem    

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Non-convex sparse optimization-based impact force identification with limited vibration measurements

《机械工程前沿（英文）》 2023年 第18卷 第3期 doi: 10.1007/s11465-023-0762-2

摘要： Impact force identification is important for structure health monitoring especially in applications involving composite structures. Different from the traditional direct measurement method, the impact force identification technique is more cost effective and feasible because it only requires a few sensors to capture the system response and infer the information about the applied forces. This technique enables the acquisition of impact locations and time histories of forces, aiding in the rapid assessment of potentially damaged areas and the extent of the damage. As a typical inverse problem, impact force reconstruction and localization is a challenging task, which has led to the development of numerous methods aimed at obtaining stable solutions. The classical ℓ2 regularization method often struggles to generate sparse solutions. When solving the under-determined problem, ℓ2 regularization often identifies false forces in non-loaded regions, interfering with the accurate identification of the true impact locations. The popular ℓ1 sparse regularization, while promoting sparsity, underestimates the amplitude of impact forces, resulting in biased estimations. To alleviate such limitations, a novel non-convex sparse regularization method that uses the non-convex ℓ1−2 penalty, which is the difference of the ℓ1 and ℓ2 norms, as a regularizer, is proposed in this paper. The principle of alternating direction method of multipliers (ADMM) is introduced to tackle the non-convex model by facilitating the decomposition of the complex original problem into easily solvable subproblems. The proposed method named ℓ1−2-ADMM is applied to solve the impact force identification problem with unknown force locations, which can realize simultaneous impact localization and time history reconstruction with an under-determined, sparse sensor configuration. Simulations and experiments are performed on a composite plate to verify the identification accuracy and robustness with respect to the noise of the ℓ1−2-ADMM method. Results indicate that compared with other existing regularization methods, the ℓ1−2-ADMM method can simultaneously reconstruct and localize impact forces more accurately, facilitating sparser solutions, and yielding more accurate results.

关键词： impact force identification     inverse problem     sparse regularization     under-determined condition     alternating direction method of multipliers    

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Chemical identification and genotoxicity analysis of petrochemical industrial wastewater

Jing ZHANG, Shigong WANG, Can WANG, Hongying HU

《环境科学与工程前沿（英文）》 2012年 第6卷 第3期   页码 350-359 doi: 10.1007/s11783-012-0404-0

摘要： The actual harmful effects of industrial wastewater can not be reflected by the conventional water quality index. Therefore, the change in dissolved organic matter and the genetic toxicity of petrochemical wastewater were observed in the current study by examining the wastewater treatment plant of a large petrochemical enterprise in Northwest China. Using XAD-8, MSC, and DA-7 resins, the wastewater was separated into six fractions, namely, hydrophobic acid (HOA), hydrophobic neutral (HOB), hydrophobic alkaline, hydrophilic acid, hydrophilic alkaline, and hydrophilic neutral. Umu-test was used to detect the genetic toxicity of the wastewater samples, and fluorescence spectra were also obtained to examine genetic toxic substances. The results show that wastewater treatment facilities can effectively reduce the concentration of organic matter in petrochemical wastewater ( <0.05). However, the mixing of aniline wastewater can increase the amount of organic carbon ( <0.05) and can overload facilities. This finding shows that the mixed collection and joint treatment of different types of petrochemical wastewater can affect the water quality of the effluent. Particularly, hydrophobic substances can be difficult to remove and account for a relatively large proportion of the effluent. The mixture of aniline wastewater can increase the genetic toxicity of the effluent ( <0.05), and biologic treatment can not effectively decrease the toxicity. Most of the genetic toxicology may exist in the HOA and HOB fractions. Fluorescence spectroscopy also confirms this result, and tryptophan-like substances may play an important role in genetic toxicity.

关键词： dissolved organic matter     resin fraction     genetic toxicity     fluorescence excitation and emission matrix    

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基于实测时间序列的非线性系统恢复力识别

许斌,贺佳

《中国工程科学》 2011年 第13卷 第9期   页码 76-82

摘要：

提出一种完全基于激励和结构响应实测数据的结构动力系统非线性恢复力识别方法，并通过在一个4层钢结构模型中引入具有非线性特性的磁流变阻尼器（MR）模拟非线性恢复力，基于此模型结构在不同的激励方式下的动力响应测量数据，验证了该方法的有效性。对于结构的各自由度均受到激励的情况，运用最小二乘拟合算法识别出等效线性系统的物理参数（质量、刚度和阻尼矩阵），进而得到模型结构振动过程中MR阻尼力随时间变化情况并与实验实测结果进行了比较。针对结构仅在有限自由度上受到激励的情况，对以上方法进行了改进，提出了一种非线性系统恢复力的非参数化识别方法，利用结构中弹性恢复力的对称关系，分步确定了结构各层间恢复力模型，从而得到MR恢复力的大小并与实测结果进行了比较。结果表明，基于时域实测信号的非线性系统恢复力识别法在完整激励和非完整激励下均能有效地识别结构的非线性恢复力特性。文章所述方法可以运用于工程结构在动力荷载作用下的损伤发生发展过程的监测与识别。

关键词： 非线性恢复力     磁流变阻尼器     最小二乘拟合     等效线性系统     非参数化模型    

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Study on damping properties of magnetorheological damper

ZHOU Yu-feng, CHEN Hua-ling

《机械工程前沿（英文）》 2006年 第1卷 第4期   页码 452-455 doi: 10.1007/s11465-006-0057-4

摘要： To research the properties of a new kind of smart controllable MR (magnetorheological) fluid, in this paper, the rheological models are discussed. On the basis of analyzing the structural forms of MR dampers, an improved structure of the MR damper is introduced; the properties of the novel MR damper are then tested. The experimental results reveal that the Herschel-Bulkley model predicts the force-velocity well; the damping properties of the ameliorated structure of the MR damper have improved; when the excitation is a trigonal signal, the MR damper reveals a thinning effect at high velocity; and when the excitation is a sinusoidal signal, the MR damper reveals a nonlinear hysteretic property between the damping force and relative velocity. Finally, the main unsolved problems have been put forward.

关键词： nonlinear hysteretic     force-velocity     unsolved     excitation     magnetorheological    

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Identification of sources, characteristics and photochemical transformations of dissolved organic matter

《环境科学与工程前沿（英文）》 2021年 第15卷 第5期 doi: 10.1007/s11783-020-1340-z

摘要：

• The source of DOM in surface water and sediment is inconsistent.

关键词： Dissolved organic matter     Parallel factor analysis     Excitation-emission matrices     Photodegradation    

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Modeling limit force capacities of high force to volume lead extrusion dampers

《结构与土木工程前沿（英文）》 2021年 第15卷 第3期   页码 609-622 doi: 10.1007/s11709-021-0724-x

摘要： Lead extrusion dampers are supplemental energy-dissipation devices that are used to mitigate seismic structural damage. Small volumetric sizes and high force capacities define high-force-to-volume (HF2V) devices, which can absorb significant response energy without sacrificial damage. However, the design of such devices for specific force capacities has proven difficult based on the complexities of their internal reaction mechanisms, leading to the adoption of empirical approaches. This study developed upper- and lower-bound force capacity estimates from analytical mechanics based on direct and indirect metal extrusion for guiding design. The derived equations are strictly functions of HF2V device geometric parameters, lead material properties, and extrusion mechanics. The upper-bound estimates from direct and indirect extrusion are denoted as (FUB,1, FUB,2) and (FUB,3, FUB,4), respectively, and the lower-bound estimates are denoted as (FLB, FLB,1) based on the combination of extrusion and friction forces. The proposed models were validated by comparing the predicted bounds to experimental force capacity data from 15 experimental HF2V device tests. The experimental device forces all lie above the lower-bound estimates (FLB, FLB,1) and below the upper-bound estimates (FUB,1, FUB,2, FUB,4). Overall, the (FLB, FUB,2) pair provides wider bounds and the (FLB,1, FUB,4/FUB,1) pair provides narrower bounds. The (FLB,1, FUB,1) pair has a mean lower-bound gap of 36%, meaning the lower bound was 74% of the actual device force on average. The mean upper-bound gap was 33%. The bulge area and cylinder diameter of HF2V devices are key parameters affecting device forces. These relatively tight bounds provide useful mechanics-based predictive design guides for ensuring that device forces are within the targeted design range after manufacturing.

关键词： extrusion     lead dampers     upper and lower bound     analytical modelling     limit force    

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同步发电机励磁系统中PWM控制的仿真研究

贾贵玺,徐伟,郭宝钥,张臣堂

《中国工程科学》 2005年 第7卷 第6期   页码 50-53

摘要：

优良的励磁控制系统不仅可以保证发电机运行的可靠性和稳定性，而且可有效地提髙发电机和电力系统技术指标。同步发电机励磁系统采用了PWM整流技术，实现励磁电流低谐波和励磁功率单元高功率因数转换，提高了发电机供电质量，并用MATLAB对设计系统做出仿真验证，证明该设计对改善发电机输出电压、提高功率单元电能利用率有明显效果。

关键词： PWM     高功率因数     励磁系统     Matlab仿真    

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分层空时码多载波CDMA的译码与检测

杨洁,酆广增

《中国工程科学》 2007年 第9卷 第1期   页码 58-62

摘要：

研究V－BLAST MIMO MC－CDMA下行系统。提出了一种对每个子载波进行V－BLAST译码的非线性 算法，对不同天线数、用户数情况进行了系统的仿真和分析，并对V－BLAST译码的线性和非线性算法进行了系 统仿真比较。

关键词： 多输入多输出     正交频分复用     分层空时码     迫零算法     最小均方误差    

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Greenhouse gas emissions mitigation and economic viability of sugar crops in China

《农业科学与工程前沿（英文）》 doi: 10.15302/J-FASE-2023529

摘要：

● Sugarcane and sugar beet yield and carbon footprint rose with time but profit declined

关键词： Economic profits     GHG emissions     labor input     nitrogen input     sugar    

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Solar photovoltaic fed dual input LED lighting system with constant illumination control

Kinattingal SUNDARESWARAN,Kevin Ark KUMAR,Payyalore Raman VENKATESWARAN,Sankaran PALANI

《能源前沿（英文）》 2016年 第10卷 第4期   页码 473-478 doi: 10.1007/s11708-016-0420-z

摘要： A dual input LED lighting scheme with constant illumination is proposed in this paper. The scheme employs a photovoltaic array as the first input and a battery as the second one. A microcontroller is programmed to operate a changeover switch as well as a DC-DC converter for uninterrupted and constant illumination in work place. The scheme is suitable for conference halls, laboratories, clean rooms, marriage halls, theaters, etc. The complete modeling, design and experimentation of the proposed scheme are explained and the economic viability of the scheme is justified.

关键词： photovoltaic     LED light     dual input     P&O algorithm    

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一种基于子带激励替换的窄带语音水印算法 Article

Wei LIU, Ai-qun HU

《信息与电子工程前沿（英文）》 2017年 第18卷 第5期   页码 627-643 doi: 10.1631/FITEE.1601503

摘要： 本文建议了一种新的窄带语音水印算法，该算法将部分语音信号替换为一个经过幅度调节和频谱成形的隐蔽信号。文中从理论上证明了若仅对一小部分载体语音作修改，则不但可以建立一个用于隐蔽通信的理想信道模型，而且还能确保隐藏信号的不可感知性和带水印信号的可懂度。在此基础上，文中建议了一个实际的系统模型。在嵌入器中，使用了能量规范化准则，使得通带水印信号的能量与原始通带语音激励信号的能量相等，然后使用合成滤波器来对该水印信号进行频谱成形。在提取器中，先用带通滤波器去除带外信号，然后用分析滤波器对失真进行补偿。实验结果显示，本文建议算法的数据速率可达400 bits/s，具有更佳的带宽效率，且有良好的不可感知性。此外，该算法对实际应用中的各种攻击也是顽健的。

关键词： 分析滤波器；线性预测；窄带语音水印；通带激励替代；能量规范化；谱包络成形；合成滤波器    

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动态双输入双输出的倾斜镜系统建模 Article

Hong SONG, Jia-heng ZHANG, Ping YANG, Hao-cai HUANG, Shu-yue ZHAN, Teng-jun LIU, Yi-lu GUO, Hang-zhou WANG, Hui HUANG, Quan-quan MU, Mei-fen FANG, Ming-yuan YANG

《信息与电子工程前沿（英文）》 2017年 第18卷 第10期   页码 1488-1498 doi: 10.1631/FITEE.1601221

摘要： 本文主要探究了在传感器采样频率较高（如高速相机、位置传感器）、倾斜镜动态特性不可忽略的情况下，如何基于实验数据建立开环倾斜镜系统的动态耦合数学模型的问题。分析了系统的动态特性以及输入与输出之间的耦合，提出了基于倾斜镜系统的输入输出数据、采用子空间辨识算法建立倾斜镜系统动态耦合数学模型的方法，并通过实验评估了模型的准确性和建模方法的可行性。实验结果显示，通过该方法所建立的倾斜镜动态耦合模型的VAF（variance-accounted-for）值达到了97%，其准确性相比传统的静态模型有了很大提高，验证了建模方法的可行性。研究成果可用于闭环倾斜镜系统优化反馈控制器的设计，提高系统对于光束偏移矫正的性能。

关键词： 倾斜镜；动态系统；输出输出耦合；物理建模；子空间辨识    

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Cutting CO emissions through demand side regulation: Implications from multi-regional input–output linear

《工程管理前沿（英文）》   页码 452-461 doi: 10.1007/s42524-022-0209-1

摘要： This study combines multi-regional input–output (MRIO) model with linear programming (LP) model to explore economic structure adjustment strategies for the reduction of carbon dioxide (CO2) emissions. A particular feature of this study is the identification of the optimal regulation sequence of final products in various regions to reduce CO2 emissions with the minimum loss in gross domestic product (GDP). By using China’s MRIO tables 2017 with 28 regions and 42 economic sectors, results show that reduction in final demand leads to simultaneous reductions in GDP and CO2 emissions. Nevertheless, certain demand side regulation strategy can be adopted to lower CO2 emissions at the smallest loss of economic growth. Several key final products, such as metallurgy, nonmetal, metal, and chemical products, should first be regulated to reduce CO2 emissions at the minimum loss in GDP. Most of these key products concentrate in the coastal developed regions in China. The proposed MRIO–LP model considers the inter-relationship among various sectors and regions, and can aid policy makers in designing effective policy for industrial structure adjustment at the regional level to achieve the national environmental and economic targets.

关键词： CO2 emissions     demand side regulation     multi-regional input–output model     linear programming model    

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Quality control based on electrode displacement and force in resistance spot welding

Chuntao JI, Lipeng DENG

《机械工程前沿（英文）》 2010年 第5卷 第4期   页码 412-417 doi: 10.1007/s11465-010-0114-x

摘要： The behaviors of electrode displacement and force during spot welding under various conditions, such as different weld currents, electrode forces, and welding times, were studied. Tests were conducted on a 170?kVA MFDC spot welder. Data were collected via a multichannel high-speed data acquisition system and were analyzed with MATLAB. Behaviors of 5182 aluminum and mild steel in spot welding were compared. Results show that nugget expansion rate does not reach zero for aluminium as it does for mild steel as nugget grew to a certain size. A linear relationship is found between the nugget size and maximum expansion that facilitates online weld quality evaluation. An electrode force peak is observed and believed relevant to the sufficient nugget size.

关键词： aluminum     electrode displacement     electrode force     nugget size     data acquisition    

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标题 作者 时间 类型 操作

Approximation of structural damping and input excitation force

Mohammad SALAVATI

期刊论文

Non-convex sparse optimization-based impact force identification with limited vibration measurements

期刊论文

Chemical identification and genotoxicity analysis of petrochemical industrial wastewater

Jing ZHANG, Shigong WANG, Can WANG, Hongying HU

期刊论文

基于实测时间序列的非线性系统恢复力识别

许斌,贺佳

期刊论文

Study on damping properties of magnetorheological damper

ZHOU Yu-feng, CHEN Hua-ling

期刊论文

Identification of sources, characteristics and photochemical transformations of dissolved organic matter

期刊论文

Modeling limit force capacities of high force to volume lead extrusion dampers

期刊论文

同步发电机励磁系统中PWM控制的仿真研究

贾贵玺,徐伟,郭宝钥,张臣堂

期刊论文

分层空时码多载波CDMA的译码与检测

杨洁,酆广增

期刊论文

Greenhouse gas emissions mitigation and economic viability of sugar crops in China

期刊论文

Solar photovoltaic fed dual input LED lighting system with constant illumination control

Kinattingal SUNDARESWARAN,Kevin Ark KUMAR,Payyalore Raman VENKATESWARAN,Sankaran PALANI

期刊论文

一种基于子带激励替换的窄带语音水印算法

Wei LIU, Ai-qun HU

期刊论文

动态双输入双输出的倾斜镜系统建模

Hong SONG, Jia-heng ZHANG, Ping YANG, Hao-cai HUANG, Shu-yue ZHAN, Teng-jun LIU, Yi-lu GUO, Hang-zhou WANG, Hui HUANG, Quan-quan MU, Mei-fen FANG, Ming-yuan YANG

期刊论文

Cutting CO emissions through demand side regulation: Implications from multi-regional input–output linear

期刊论文

Quality control based on electrode displacement and force in resistance spot welding

Chuntao JI, Lipeng DENG

期刊论文