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Terahertz time-domain spectroscopy of high-pressure flames

Jason BASSI, Mark STRINGER, Bob MILES, Yang ZHANG

《能源前沿（英文）》 2009年 第3卷 第2期   页码 123-133 doi: 10.1007/s11708-009-0033-x

摘要： Laser spectroscopy in the visible and near infrared is widely used as a diagnostic tool for combustion devices, but this approach is difficult at high pressures within a sooty flame itself. High soot concentrations render flames opaque to visible light, but they remain transparent to far-infrared or terahertz (THz) radiation. The first far-infrared absorption spectra, to the best of our knowledge, of sooty, non-premixed, ethylene high-pressure flames covering the region of 0.2-2.5 THz is presented. A specially designed high-pressure burner which is optically accessible to THz radiation has been built allowing flame transmission measurements up to pressures of 1.6 MPa. Calculations of the theoretical combustion species absorption spectra in the 0.2-3 THz range have shown that almost all the observable features arise from H O. A few OH (1.84 and 2.51 THz), CH (2.58 THz), and NH (1.77 and 2.95 THz) absorption lines are also observable in principle. A large number of H O absorption lines are observed in the ground vibrational in a laminar non-premixed, sooty flame (ethylene) at pressures up to 1.6 MPa.

关键词： terahertz time-domain spectroscopy     high-pressure flames     H2O absorption lines    

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利用太赫兹时域光谱法和微腔器件检测样品：综述 Special Feature on Precision Measurement and Instr

Lin CHEN, Deng-gao LIAO, Xu-guang GUO, Jia-yu ZHAO, Yi-ming ZHU, Song-lin ZHUANG

《信息与电子工程前沿（英文）》 2019年 第20卷 第5期   页码 591-607 doi: 10.1631/FITEE.1800633

摘要： 简要回顾了上海理工大学在用于探测样品的太赫兹时域光谱系统和微腔器件领域的研究进展。首先，通过施加高电场研究了基于砷化镓m-i-n二极管的宽频太赫兹辐射源。然后，详细介绍了我们实验室产生的自由空间太赫兹时域光谱系统和光纤耦合太赫兹时域光谱系统及其在药物/癌症检测中的应用。为进一步提高信噪比和高灵敏度，我们引入3种通用微腔结构实现微量样品检测。本文总结了这些结构的特性、性能和潜在的传感应用。

关键词： 太赫兹时域光谱；微腔；金属孔阵列；波导腔；伪局域表面等离子体    

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Time-domain and frequency-domain approaches to identification of bridge flutter derivatives

Zhengqing CHEN

《结构与土木工程前沿（英文）》 2009年 第3卷 第2期   页码 173-179 doi: 10.1007/s11709-009-0034-1

摘要： Flutter derivatives are essential for flutter analysis of long-span bridges, and they are generally identified from the vibration testing data of a sectional model suspended in a wind tunnel. Making use of the forced vibration testing data of three sectional models, namely, a thin-plate model, a nearly streamlined model, and a bluff-body model, a comparative study was made to identify the flutter derivatives of each model by using a time-domain method and a frequency-domain method. It was shown that all the flutter derivatives of the thin-plate model identified with the frequency-domain method and time-domain method, respectively, agree very well. Moreover, some of the flutter derivatives of each of the other two models identified with the two methods deviate to some extent. More precisely, the frequency-domain method usually results in smooth curves of the flutter derivatives. The formulation of time-domain method makes the identification results of flutter derivatives relatively sensitive to the signal phase lag between vibration state vector and aerodynamic forces and also prone to be disturbed by noise and nonlinearity.

关键词： long-span bridges     wind-induced vibration     flutter derivatives     forced vibration test     time-domain method     frequency-domain method    

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Time of flight improved thermally grown oxide thickness measurement with terahertz spectroscopy

《机械工程前沿（英文）》 2022年 第17卷 第4期 doi: 10.1007/s11465-022-0705-3

摘要： As a nondestructive testing technique, terahertz time-domain spectroscopy technology is commonly used to measure the thickness of ceramic coat in thermal barrier coatings (TBCs). However, the invisibility of ceramic/thermally grown oxide (TGO) reflective wave leads to the measurement failure of natural growth TGO whose thickness is below 10 μm in TBCs. To detect and monitor TGO in the emergence stage, a time of flight (TOF) improved TGO thickness measurement method is proposed. A simulative investigation on propagation characteristics of terahertz shows the linear relationship between TGO thickness and phase shift of feature wave. The accurate TOF increment could be acquired from wavelet soft threshold and cross-correlation function with negative effect reduction of environmental noise and system oscillation. Thus, the TGO thickness could be obtained efficiently from the TOF increment of the monitor area with different heating times. The averaged error of 1.61 μm in experimental results demonstrates the highly accurate and robust measurement of the proposed method, making it attractive for condition monitoring and life prediction of TBCs.

关键词： thermal barrier coatings     thermally grown oxide     terahertz spectroscopy     time of flight    

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Damage identification in connections of moment frames using time domain responses and an optimization

《结构与土木工程前沿（英文）》 2021年 第15卷 第4期   页码 851-866 doi: 10.1007/s11709-021-0739-3

摘要： Damage is defined as changes to the material and/or geometric properties of a structural system, comprising changes to the boundary conditions and system connectivity, adversely affecting the system’s performance. Inspecting the elements of structures, particularly critical components, is vital to evaluate the structural lifespan and safety. In this study, an optimization-based method for joint damage identification of moment frames using the time-domain responses is introduced. The beam-to-column connection in a metallic moment frame structure is modeled by a zero-length rotational spring at both ends of the beam element. For each connection, an end-fixity factor is specified, which changes between 0 and 1. Then, the problem of joint damage identification is converted to a standard optimization problem. An objective function is defined using the nodal point accelerations extracted from the damaged structure and an analytical model of the structure in which the nodal accelerations are obtained using the Newmark procedure. The optimization problem is solved by an improved differential evolution algorithm (IDEA) for identifying the location and severity of the damage. To assess the capability of the proposed method, two numerical examples via different damage scenarios are considered. Then, a comparison between the proposed method and the existing damage identification method is provided. The outcomes reveal the high efficiency of the proposed method for finding the severity and location of joint damage considering noise effects.

关键词： damage identification     beam-to-column connection     time-domain response     optimization    

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A super-element approach for structural identification in time domain

LI Jie, ZHAO Xin

《机械工程前沿（英文）》 2006年 第1卷 第2期   页码 215-221 doi: 10.1007/s11465-006-0004-4

摘要： For most time-domain identification methods, a complete measurement for unique identification results is required for structural responses. However, the number of transducers is commonly far less than the number of structural degrees of freedom (DOFs) in practical applications, and thus make the time-domain identification methods rarely feasible for practical systems. A super-element approach is proposed in this study to identify the structural parameters of a large-scale structure in the time domain. The most interesting feature of the proposed super-element approach is its divide-and-conquer ability, which can be applied to identify large-scale structures using a relatively small number of transducers. The super-element model used for time domain identification is first discussed in this study. Then a parameterization procedure based on the sensitivities of response forces is introduced to establish the identification equations of super-elements. Some principles are suggested on effective decomposing of the whole structure into super-elements for identification purposes. Numerical simulations are conducted at the end of this study. The numerical results show that all structural parameters can be identified using a relatively small number of transducers, and the computational time can also be greatly shortened.

关键词： numerical     effective decomposing     parameterization procedure     divide-and-conquer ability     time-domain identification    

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On subsurface box-shaped lined tunnel under incident SH-wave propagation

《结构与土木工程前沿（英文）》 2021年 第15卷 第4期   页码 948-960 doi: 10.1007/s11709-021-0740-x

摘要： In this paper, a half-plane time-domain boundary element method is applied to obtain the seismic ground response, including a subsurface box-shaped lined tunnel deployed in a linear homogenous elastic medium exposed to obliquely incident SH-waves. Only the boundary around the tunnel is required to be discretized. To prepare an appropriate model by quadratic elements, a double-node procedure is used to receive dual boundary fields at corners as well as change the direction of the normal vector. After encoding the method in a previously confirmed computer program, a numerical study is carried out to sensitize some effective parameters, including frequency content and incident wave angle for obtaining a surface response. The depth and impedance ratio of the lining are assumed to be unvaried. The responses are illustrated in the time and frequency domains as two/three-dimensional graphs. The results showed that subsurface openings with sharp corners distorted the propagation path of the anti-plane waves to achieve the critical states on the ground surface. The present approach can be proposed to civil engineers for preparing simple underground box-shaped models with angular boundaries.

关键词： box-lined tunnel     half-plane BEM     surface response     SH-wave     time-domain    

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Topology optimization of piezoelectric bi-material actuators with velocity feedback control

Mariana MORETTI, Emílio C. N. SILVA

《机械工程前沿（英文）》 2019年 第14卷 第2期   页码 190-200 doi: 10.1007/s11465-019-0537-y

摘要： In recent years, the new technologies and discoveries on manufacturing materials have encouraged researchers to investigate the appearance of material properties that are not naturally available. Materials featuring a specific stiffness, or structures that combine non-structural and structural functions are applied in the aerospace, electronics and medical industry fields. Particularly, structures designed for dynamic actuation with reduced vibration response are the focus of this work. The bi-material and multifunctional concepts are considered for the design of a controlled piezoelectric actuator with vibration suppression by means of the topology optimization method (TOM). The bi-material piezoelectric actuator (BPEA) has its metallic host layer designed by the TOM, which defines the structural function, and the electric function is given by two piezo-ceramic layers that act as a sensor and an actuator coupled with a constant gain active velocity feedback control (AVFC). The AVFC, provided by the piezoelectric layers, affects the structural damping of the system through the velocity state variables readings in time domain. The dynamic equation analyzed throughout the optimization procedure is fully elaborated and implemented. The dynamic response for the rectangular four-noded FE analysis is obtained by the Newmark’s time-integration method, which is applied to the physical and the adjoint systems, given that the adjoint formulation is needed for the sensitivity analysis. A gradient-based optimization method is applied to minimize the displacement energy output measured at a predefined degree-of-freedom of the BPEA when a transient mechanical load is applied. Results are obtained for different control gain values to evaluate their influence on the final topology.

关键词： topology optimization method     bi-material piezoactuator     active velocity feedback control     time-domain transient analysis     host structure design     vibration suppression    

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Analytical method of capsizing probability in the time domain for ships in the random beam seas

LIU Liqin, TANG Yougang, LI Hongxia

《结构与土木工程前沿（英文）》 2007年 第1卷 第3期   页码 361-366 doi: 10.1007/s11709-007-0048-5

摘要： The methods for constructing safe basins of ships and predicting their survival probability in random waves were studied. The nonlinear differential equation of the rolling motion of ships in random beam seas was established considering nonlinear damping, nonlinear restoring moment, and random waves. The random rolling differential equation was solved in the time domain by applying the harmonic acceleration method and by synthetically considering the instantaneous state of ships and the narrowband wave energy spectrum. The numerical simulation of random capsizing course was brought forward, the safe basins were constructed for safe navigation, and the survival probabilities of ships were calculated. As an example, the safe basins on the rolling initial value plane were constructed for a 30.27-meter-long fishing vessel according to different initial conditions and random wave parameters. The survival probabilities of the fishing vessel under different significant wave heights were predicted. Thus, the survival probabilities of ships in random seas can be predicted quantitatively by the proposed method.

关键词： different     survival probability     different significant     nonlinear differential     narrowband    

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Improved numerical method for time domain dynamic structure-foundation interaction analysis based on

DU Jianguo, LIN Gao

《结构与土木工程前沿（英文）》 2008年 第2卷 第4期   页码 336-342 doi: 10.1007/s11709-008-0054-2

摘要： Based on the reduced set of base function in scaled boundary finite element method (SBFEM), an improved time domain numerical approach for the dynamic structure-foundation interaction analysis was proposed. With reasonable choice of the number of base functions, the degrees of freedom on the structure-foundation interface were reduced and the associated computation for the calculation of convolution integral was greatly reduced. The results of this proposed approach applied to the calculation of a gravity dam and an arch dam. The acceleration frequency response functions were calculated and the influences affected by different reduced set of base functions as well as full set were compared. It was found that a higher degree of reduced set of base functions resulted in a significant increase of computational efficiency but a little bit of loss in accuracy. When the reduced set was decreased by 60%, the efficiency may be increased to up to five times, while the loss of accuracy of peak value of response will be less than 4%. It may be concluded that the proposed approach is suitable for large-scale structure-foundation interaction analysis.

关键词： structure-foundation interface     computational efficiency     different     suitable     numerical approach    

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Progress in terahertz nondestructive testing: A review

Shuncong ZHONG

《机械工程前沿（英文）》 2019年 第14卷 第3期   页码 273-281 doi: 10.1007/s11465-018-0495-9

摘要： Terahertz (THz) waves, whose frequencies range between microwave and infrared, are part of the electromagnetic spectrum. A gap exists in THz literature because investigating THz waves is difficult due to the weak characteristics of the waves and the lack of suitable THz sources and detectors. Recently, THz nondestructive testing (NDT) technology has become an interesting topic. This review outlines several typical THz devices and systems and engineering applications of THz NDT techniques in composite materials, thermal barrier coatings, car paint films, marine protective coatings, and pharmaceutical tablet coatings. THz imaging has higher resolution but lower penetration than ultrasound imaging. This review presents the significance and advantages provided by the emerging THz NDT technique.

关键词： terahertz pulsed imaging (TPI)     nondestructive testing (NDT)     composite material     thermal barrier coating    

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Real time monitoring of bioreactor mAb IgG3 cell culture process dynamics via Fourier transform infraredspectroscopy: Implications for enabling cell culture process analytical technology?

Huiquan Wu, Erik Read, Maury White, Brittany Chavez, Kurt Brorson, Cyrus Agarabi, Mansoor Khan

《化学科学与工程前沿（英文）》 2015年 第9卷 第3期   页码 386-406 doi: 10.1007/s11705-015-1533-3

摘要： Compared to small molecule process analytical technology (PAT) applications, biotechnology product PAT applications have certain unique challenges and opportunities. Understanding process dynamics of bioreactor cell culture process is essential to establish an appropriate process control strategy for biotechnology product PAT applications. Inline spectroscopic techniques for real time monitoring of bioreactor cell culture process have the distinct potential to develop PAT approaches in manufacturing biotechnology drug products. However, the use of inline Fourier transform infrared (FTIR) spectroscopic techniques for bioreactor cell culture process monitoring has not been reported. In this work, real time inline FTIR Spectroscopy was applied to a lab scale bioreactor mAb IgG3 cell culture fluid biomolecular dynamic model. The technical feasibility of using FTIR Spectroscopy for real time tracking and monitoring four key cell culture metabolites (including glucose, glutamine, lactate, and ammonia) and protein yield at increasing levels of complexity (simple binary system, fully formulated media, actual bioreactor cell culture process) was evaluated via a stepwise approach. The FTIR fingerprints of the key metabolites were identified. The multivariate partial least squares (PLS) calibration models were established to correlate the process FTIR spectra with the concentrations of key metabolites and protein yield of in-process samples, either individually for each metabolite and protein or globally for all four metabolites simultaneously. Applying the 2 derivative pre-processing algorithm to the FTIR spectra helps to reduce the number of PLS latent variables needed significantly and thus simplify the interpretation of the PLS models. The validated PLS models show promise in predicting the concentration profiles of glucose, glutamine, lactate, and ammonia and protein yield over the course of the bioreactor cell culture process. Therefore, this work demonstrated the technical feasibility of real time monitoring of the bioreactor cell culture process via FTIR spectroscopy. Its implications for enabling cell culture PAT were discussed.

关键词： process analytical technology (PAT)     Fourier-transform infrared (FTIR) spectroscopy     partial least squares (PLS) regression     mouse IgG3     bioreactor cell culture process     real time process monitoring    

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Engineering

Raquel Portela, Susana Perez-Ferreras, Ana Serrano-Lotina, Miguel A. Bañares

《化学科学与工程前沿（英文）》 2018年 第12卷 第3期   页码 509-536 doi: 10.1007/s11705-018-1740-9

摘要：

The term operando was coined at the beginning of this century to gather the growing efforts devoted to establish structure-activity relationships by simultaneously characterizing a catalyst performance and the relevant surface chemistry during genuine catalytic operation. This approach is now widespread and consolidated; it has become an increasingly complex but efficient junction where spectroscopy, materials science, catalysis and engineering meet. While for some characterization techniques kinetically relevant reactor cells with good resolution are recently developing, the knowledge gained with magnetic resonance and X-ray and vibrational spectroscopy studies is already huge and the scope of operando methodology with these techniques is recently expanding from studies with small amounts of powdered solids to more industrially relevant catalytic systems. Engineering catalysis implies larger physical domains, and thus all sort of gradients. Space- and time- resolved multi-technique characterization of both the solid and fluid phases involved in heterogeneous catalytic reactions (including temperature data) is key to map processes from different perspectives, which allows taking into account existing heterogeneities at different scales and facing up- and down-scaling for applications ranging from microstructured reactors to industrial-like macroreactors (operating with shaped catalytic bodies and/or in integral regime). This work reviews how operando methodology is evolving toward engineered reaction systems.

关键词： operando     structured catalysts     space-resolved     time-resolved     spectroscopy    

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高精度太赫兹异频回溯天线阵列 Correspondence

Zhong-bo ZHU, Wei-dong HU, Tao QIN, Sheng LI, Xiao-jun LI, Jiang-jie ZENG, Xian-qi LIN, Leo P. LIGTHART

《信息与电子工程前沿（英文）》 2020年 第21卷 第3期   页码 377-383 doi: 10.1631/FITEE.1900581

摘要： 未来通信系统将工作于更高频率，并提供更高传输速率。频率提升将导致难以提供区域宽波束覆盖，因此灵活捷变的波束跟踪将成为技术发展的必然趋势。本文报道的太赫兹波束回溯天线阵列可为灵活捷变的波束跟踪提供良好解决方案。该天线阵列接收40 GHz的导频信号，回溯波束传输的信号是120 GHz。仿真结果表明文中所述具有三明治堆叠结构的天线阵列可成功实现入射波的回溯功能。天线辐射方向图显示该天线阵列在20°入射波条件下，其回溯波束在19.9°位置处，增益为23.87 dB，回溯方向相对误差仅为0.5%。这意味着在5 km传输距离下，水平误差仅为8.7 m。

关键词： 太赫兹；回溯天线阵列；太赫兹通信；共轭混频    

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基于钻头运动诱发套管头振动信号检测的井眼防碰监测方法

何保生,刘刚,王平双,文敏

《中国工程科学》 2011年 第13卷 第5期   页码 74-78

摘要：

针对海上加密调整井的井眼防碰问题，设计了一种井筒防碰地面监测预警系统，并进行了现场应用。系统利用加速度传感器监测通过套管传输到套管头上的钻头振动信号，利用数据采集、信号滤波放大和专门编制的监测软件记录分析传感器采集的振动信号，通过对信号的时域、频域分析，确定信号特征与井间相对距离的关系，识别钻头对风险井套管的趋近或碰撞。应用结果表明，该系统能有效感知通过地层、套管传输到套管头的钻头振动信号，并能识别出钻头对风险邻井的趋近，验证了系统在设计理论和方法上的可行性，为加密调整井的井眼防碰、保证钻井安全提供了一种有效的手段。

关键词： 调整井     防碰     风险井     振动信号     时域分析     频域分析    

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标题 作者 时间 类型 操作

Terahertz time-domain spectroscopy of high-pressure flames

Jason BASSI, Mark STRINGER, Bob MILES, Yang ZHANG

期刊论文

利用太赫兹时域光谱法和微腔器件检测样品：综述

Lin CHEN, Deng-gao LIAO, Xu-guang GUO, Jia-yu ZHAO, Yi-ming ZHU, Song-lin ZHUANG

期刊论文

Time-domain and frequency-domain approaches to identification of bridge flutter derivatives

Zhengqing CHEN

期刊论文

Time of flight improved thermally grown oxide thickness measurement with terahertz spectroscopy

期刊论文

Damage identification in connections of moment frames using time domain responses and an optimization

期刊论文

A super-element approach for structural identification in time domain

LI Jie, ZHAO Xin

期刊论文

On subsurface box-shaped lined tunnel under incident SH-wave propagation

期刊论文

Topology optimization of piezoelectric bi-material actuators with velocity feedback control

Mariana MORETTI, Emílio C. N. SILVA

期刊论文

Analytical method of capsizing probability in the time domain for ships in the random beam seas

LIU Liqin, TANG Yougang, LI Hongxia

期刊论文

Improved numerical method for time domain dynamic structure-foundation interaction analysis based on

DU Jianguo, LIN Gao

期刊论文

Progress in terahertz nondestructive testing: A review

Shuncong ZHONG

期刊论文

Real time monitoring of bioreactor mAb IgG3 cell culture process dynamics via Fourier transform infraredspectroscopy: Implications for enabling cell culture process analytical technology?

Huiquan Wu, Erik Read, Maury White, Brittany Chavez, Kurt Brorson, Cyrus Agarabi, Mansoor Khan

期刊论文

Engineering

Raquel Portela, Susana Perez-Ferreras, Ana Serrano-Lotina, Miguel A. Bañares

期刊论文

高精度太赫兹异频回溯天线阵列

Zhong-bo ZHU, Wei-dong HU, Tao QIN, Sheng LI, Xiao-jun LI, Jiang-jie ZENG, Xian-qi LIN, Leo P. LIGTHART

期刊论文

基于钻头运动诱发套管头振动信号检测的井眼防碰监测方法

何保生,刘刚,王平双,文敏

期刊论文