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Construction of interfacial dynamic bonds for high performance lignin/polymer biocomposites

《化学科学与工程前沿（英文）》 2023年第17卷第10期页码 1372-1388 doi: 10.1007/s11705-023-2302-3

摘要： Lignin is the largest natural aromatic biopolymer, but usually treated as industrial biomass waste. The development of lignin/polymer biocomposites can promote the high value utilization of lignin and the greening of polymers. However, the weak interfacial interaction between industrial lignin and polymer induces poor compatibility and serious agglomeration in polymer owing to the strong intermolecular force of lignin. As such, it is extremely difficult to prepare high performance lignin/polymer biocomposites. Recently, we proposed the strategy of in situ construction of interfacial dynamic bonds in lignin/polymer composites. By taking advantage of the abundant oxygen-containing polar groups of lignin, we inserted dynamic bonding connection such as hydrogen bonds and coordination bonds into the interphase between lignin and the polymer matrix to improve the interfacial interactions. Meanwhile, the natural amphiphilic structure characteristics of lignin were utilized to construct the hierarchical nanophase separation structure in lignin/polymer composites. The persistent problems of poor dispersity and interfacial compatibility of lignin in the polymer matrix were effectively solved. The lignin-modified polymer composites achieved simultaneously enhanced strength and toughness. This concise review systematically summarized the recent research progress of our group toward building high-performance lignin/polymer biocomposites through the design of interfacial dynamic bonds (hydrogen bonds, coordination bonds, and dynamic covalent bonds) between lignin and different polymer systems (polar plastics, rubber, polyurethane, hydrogels, and other polymers). Finally, the future development direction, main challenges, and potential solutions of lignin application in polymers were presented.

关键词： lignin polymer interfacial dynamic bonds

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Fictitious soil pile model for dynamic analysis of pipe piles under high-strain conditions

《结构与土木工程前沿（英文）》页码 915-934 doi: 10.1007/s11709-023-0907-8

摘要： A fictitious soil pile (FSP) model is developed to simulate the behavior of pipe piles with soil plugs undergoing high-strain dynamic impact loading. The developed model simulates the base soil with a fictitious hollow pile fully filled with a soil plug extending at a cone angle from the pile toe to the bedrock. The friction on the outside and inside of the pile walls is distinguished using different shaft models, and the propagation of stress waves in the base soil and soil plug is considered. The motions of the pile−soil system are solved by discretizing them into spring-mass model based on the finite difference method. Comparisons of the predictions of the proposed model and conventional numerical models, as well as measurements for pipe piles in field tests subjected to impact loading, validate the accuracy of the proposed model. A parametric analysis is conducted to illustrate the influence of the model parameters on the pile dynamic response. Finally, the effective length of the FSP is proposed to approximate the affected soil zone below the pipe pile toe, and some guidance is provided for the selection of the model parameters.

关键词： fictitious soil pile soil plug pipe piles high-strain dynamic analysis one-dimensional wave theory pile dynamics

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Confining pressure effect on dynamic response of high rockfill dam

Xuexing CAO, Yunlong HE, Kun XIONG,

《结构与土木工程前沿（英文）》 2010年第4卷第1期页码 116-126 doi: 10.1007/s11709-010-0014-5

摘要： Studies show that the dynamic properties of rockfill are strongly dependent on the confining pressure. Therefore, confining pressure effect has become a very important factor in the seismic analysis of high rockfill dam. The relationships of dynamic shear modulus versus dynamic shear strain and damping ratio versus dynamic shear strain had been improved to a certain degree on the basic of widely used Hardin-Drnevich constitutive model in this paper. Then a new model that could consider confining pressure effect has been established. Regression analysis was carried out of the dynamic triaxial experimental data of the damming materials in the Changheba hydropower station of Sichun Province, China. The results show that, the new model can fit the test data well under various confining pressures. A corresponding computational procedure was compiled and applied in the dynamic response analysis of the Changheba Dam. Comparing the calculation results between the new constitutive model and the ordinary Hardin-Drnevich model, it can be seen that the result is conservative to some extent without considering confining pressure effect.

关键词： confining pressure effect high rockfill dam dynamic response Hardin-Drnevich constitutive model

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A block zero-padding method based on DCFT for L1 parameter estimations in weak signal and high dynamic

Chao WU,Lu-ping XU,Hua ZHANG,Wen-bo ZHAO

《信息与电子工程前沿（英文）》 2015年第16卷第9期页码 796-804 doi: 10.1631/FITEE.1500058

摘要： Weak L1 signal acquisition in a high dynamic environment primarily faces a challenge: the integration peak is negatively influenced by the possible bit sign reversal every 20 ms and the frequency error. The block accumulating semi-coherent integration of correlations (BASIC) is a state-of-the-art method, but calculating the inter-block conjugate products restricts BASIC in a low signal-to-noise ratio (SNR) acquisition. We propose a block zero-padding method based on a discrete chirp-Fourier transform (DCFT) for parameter estimations in weak signal and high dynamic environments. Compared with the conventional receiver architecture that uses closed-loop acquisition and tracking, it is more suitable for open-loop acquisition. The proposed method combines DCFT and block zero-padding. In this way, the post-correlation signal is coherently post-integrated with the bit sequence stripped off, and the high dynamic parameters are precisely estimated using the threshold set based on a false alarm probability. In addition, the detection performance of the proposed method is analyzed. Simulation results show that compared with the BASIC method, the proposed method can precisely detect the high dynamic parameters in lower SNR when the length of the received signal is fixed.

关键词： Threshold detection Discrete chirp-Fourier transform Block zero-padding High dynamic Weak L1 signal acquisition

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高铁客站建设动态互动管理理论研究

郑健

《中国工程科学》 2011年第13卷第8期页码 31-35

摘要：

高速铁路及其客站建设是我国经济社会持续发展的必然产物，其建设与运营将促进区域经济一体化及都市圈和经济带的形成与发展，从而为经济社会发展提供动力与支撑。党的十六大以来，伴随着中国高铁的快速发展，高铁客站迎来了难得的发展机遇。截至2011年3月，共建成北京南、武汉、广州南、上海虹桥等139座高铁客站。笔者分析了高铁客站与经济社会发展之间的互动关系，结合大规模高铁客站建设实践，研究提出了以经济社会发展演化规律为指导的战略、项目集与项目的动态互动模型和管理理论，为科学制定我国高铁客站建设的战略目标体系及项目集、单项目管理提供了理论依据。

关键词：高铁客站经济社会项目集动态互动管理

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Evaluation of the power consumption of a high-speed parallel robot

Gang HAN, Fugui XIE, Xin-Jun LIU

《机械工程前沿（英文）》 2018年第13卷第2期页码 167-178 doi: 10.1007/s11465-017-0456-8

摘要：

An inverse dynamic model of a high-speed parallel robot is established based on the virtual work principle. With this dynamic model, a new evaluation method is proposed to measure the power consumption of the robot during pick-and-place tasks. The power vector is extended in this method and used to represent the collinear velocity and acceleration of the moving platform. Afterward, several dynamic performance indices, which are homogenous and possess obvious physical meanings, are proposed. These indices can evaluate the power input and output transmissibility of the robot in a workspace. The distributions of the power input and output transmissibility of the high-speed parallel robot are derived with these indices and clearly illustrated in atlases. Furtherly, a low-power-consumption workspace is selected for the robot.

关键词： high-speed parallel robot dynamic model power consumption evaluation method power vector

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Rosin side chain type catalyst-free vitrimers with high cross-link density, mechanical strength, and

《化学科学与工程前沿（英文）》 2023年第17卷第9期页码 1267-1279 doi: 10.1007/s11705-022-2291-7

摘要： The emergence of vitrimer, a new class of polymer materials can address the problem of recyclability, reprocess ability and recyclability of thermosetting plastics. Rosin, a natural product, is an ideal raw material for the preparation of polymers in a more sustainable way. Nevertheless, due to the huge steric hindrance caused by the hydrogenated phenanthrene ring structure, the cross-link density of materials is frequently lowered. In this study, hydrogenated rosin was adopted for preparing hydrogenated rosin side-chain type diacids, which were reacted with mixed epoxy to obtain rosin side-chain type vitrimers. It was completely characterized by differential scanning calorimetry test, thermogravimetric analysis, shape memory test and self-healing test. The prepared vitrimers exhibited good self-healing properties, excellent heat resistance (T_d = 352 °C) as well as high mechanical properties (tensile strength of 46.75 MPa). The tricyclic diterpene structure of rosin was introduced into the side chain in order to avoid the reduction of cross-link density resulting from the huge steric hindrance of the rigid tricyclic hydrophenylene skeleton. Vitrimers can undergo dynamic transesterification reaction without external catalysts due to the autocatalytic effect of tertiary amines from epoxy. Moreover, our work expanded the application field of rosin, increased the added value of rosin, and provided a novel method for preparing rosin-based vitrimers with ideal properties.

关键词： vitrimers rosin catalyst-free high mechanical properties dynamic transesterification reaction

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Dynamic characteristics of molten droplets and hot particles falling in liquid pool

Liangxing LI, Weimin MA, Huixiong LI, Tingkuan CHEN,

《能源前沿（英文）》 2010年第4卷第2期页码 246-251 doi: 10.1007/s11708-009-0077-y

摘要： The dynamic characteristics of molten droplets and hot particles at the very beginning of their fall into coolant pools are presented. The falling course of a single droplet or a single hot particle was recorded by a high-speed camera and a curve of velocity . time was obtained. Emphasis was placed on the effects of the droplet’s size and temperature, the coolant’s temperature and properties, and the droplet’s physical properties on the moving behavior. The results for the all cases showed that the velocity of a falling droplet/particle decreased rapidly but rebounded shortly, at the beginning of droplet/particle falling in the coolant. Following such a V-shaped evolution in velocity, the droplet/particle slows down gradually to a comparatively steady velocity. An increase in either coolant temperature or droplet temperature results in a larger velocity variation in the “J-region”, but a smaller deceleration when it moves out of the “J-region”. The elevated volatility of a coolant leads to a steeper deceleration in the “J-region” and beyond. The bigger size of a particle leads to a greater velocity variation in the “J-region” and terminal velocity. A high melting point and thermal conductivity as well as lower heat capacity contribute to dramatic variation in the “J-region” and low terminal velocity.

关键词： dynamic characteristics molten droplets high-temperature particles fuel and coolant interactions

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Dynamic analyses of steel-reinforced super high-strength concrete columns

JIA Jinqing, JIANG Rui, XU Shilang, HOU Tong

《结构与土木工程前沿（英文）》 2007年第1卷第2期页码 240-246 doi: 10.1007/s11709-007-0030-2

摘要： The dynamic behaviors of steel-reinforced super high-strength concrete columns under seismic loading were studied with a series of experiments. Thirteen specimens, with concrete strengths ranging from 94.9 to 105.4 MPa and shear-span ratios of 2.75, were manufactured. The axial load ratio and the stirrup reinforcement ratio were the main experimental variables affecting the dynamic behavior of the specimens. The columns under low cyclic lateral loading mainly failed in the flexural-shear mode. Shear force-displacement hysteretic curves and skeleton curves were drawn. The coefficients of the specimens displacement ductility were calculated. Experimental results indicate that ductility decreases while the axial load ratio increases, but it increases when the stirrup reinforcement ratio increases. The limit values of the axial load ratio and the minimum stirrup reinforcement ratio of the columns were investigated to satisfy definite ductility requirements. These values were suggested as references of engineering applications and of the amendment of the current Chinese design code of steel reinforced concrete composite structures.

关键词： amendment flexural-shear force-displacement hysteretic definite ductility skeleton

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XB高精度火箭橇试验滑轨

杨兴邦

《中国工程科学》 2000年第2卷第10期页码 98-104

摘要：

火箭橇试验滑轨是一种大型地面动态模拟试验设备，用于研究试验件在空中高速度、高加速度运行时所遇到的诸多技术问题，其技术核心是一百万分之一的轨道直线性相对精度。它要求具有稳定的滑轨基础、高直线度准直基准线和光滑平顺的钢轨作为基本条件，需要采用钢轨精密机械加工、钢轨焊接、焊缝超声波探伤、轨道张拉锚固锁定、轨道直线度调整等新工艺技术。我国已成功地建成世界上唯一的、钢轨经精密机械加工后再全程焊接的XB高精度火箭橇试验滑轨。文章论述了它的诞生背景、设计思路、技术方案、技术与建造特点以及应用展望，该滑轨直线度达到世界先进水平。

关键词：火箭滑橇试验滑轨地面动态模拟试验

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基于时序优化长短期记忆和自适应阈值的高排放重型柴油车识别 Research Article

许镇义1,王仁军1,2,曹洋1,3,4,康宇1,3,4

《信息与电子工程前沿（英文）》 2023年第24卷第11期页码 1633-1646 doi: 10.1631/FITEE.2300005

摘要：在实际场景中，重型柴油车是城市氮氧化物的重要来源，其排放的氮氧化物（NOx）占车辆总排放量的80％以上，颗粒物（PM）占90％以上。检测和控制重型柴油车的排放对保护公众健康至关重要。目前，道路上的车辆必须每6个月或每年定期检测一次，在车辆检查站过滤出高排放的移动源。然而，由于年检间隔时间较长，很难及时有效地筛选出高排放车辆，而且固定的阈值不能适应车辆驾驶工况的动态变化。车载诊断设备（OBD）安装在车辆内部，可以连续跟踪和实时记录排放数据。本文提出一种时间优化长短期记忆（LSTM）和自适应动态阈值方法，使用OBD数据识别重型高排放车辆。首先，建立一个时间优化LSTM排放预测模型，以解决实际中大量OBD数据流造成的时间步注意力偏重问题。然后，利用灵活的阈值标准检测浓度预测误差序列，以区分异常排放情况，该阈值随驾驶条件变化自适应计算得到。最后，引入时间序列的相似性度量策略，以纠正一些假的异常结果。在3个真实OBD时间序列排放数据集上的实验表明，该方法得到优异的高排放源识别结果。

关键词：高排放识别；时序优化；车载诊断设备（OBD）；动态阈值

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客运专线路基动态施工控制及沉降预测

王国体,吴吉祥,李刚,王轶昕

《中国工程科学》 2011年第13卷第3期页码 50-55

摘要：

依据合武（合肥-武汉）Ⅰ标段设置路基沉降观测的数据，提出了对高速铁路路基施工进行动态控制方程的公式形式和工后路基沉降预测的依据与具体实现，并结合典型观测数据进行分析和路基施工控制，确保路基质量、沉降、工期要求。

关键词：高速铁路客运专线路基施工施工动态控制沉降预测

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A thermally flexible and multi-site tactile sensor for remote 3D dynamic sensing imaging

Guoting Xia, Yinuo Huang, Fujiang Li, Licheng Wang, Jinbo Pang, Liwei Li, Kai Wang

《化学科学与工程前沿（英文）》 2020年第14卷第6期页码 1039-1051 doi: 10.1007/s11705-019-1901-5

摘要： A flexible, multi-site tactile and thermal sensor (MTTS) based on polyvinylidene fluoride (resolution 50 × 50) is reported. It can be used to implement spatial mapping caused by tactile and thermal events and record the two-dimensional motion trajectory of a tracked target object. The output voltage and current signal are recorded as a mapping by sensing the external pressure and thermal radiation stimulus, and the response distribution is dynamically observed on the three-dimensional interface. Through the mapping relationship between the established piezoelectric and pyroelectric signals, the piezoelectric component and the pyroelectric component are effectively extracted from the composite signals. The MTTS has a good sensitivity for tactile and thermal detection, and the electrodes have good synchronism. In addition, the signal interference is less than 9.5% and decreases as the pressure decreases after the distance between adjacent sites exceeds 200 µm. The integration of MTTS and signal processing units has potential applications in human-machine interaction systems, health status detection and smart assistive devices.

关键词： tactile/thermal sensor piezoelectric/pyroelectric effects high resolution spatial mapping motion monitoring

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Green Construction of National Speed Skating Oval

《工程管理前沿（英文）》 2022年第9卷第1期页码 170-176 doi: 10.1007/s42524-021-0177-x

关键词： super large-span cable net structure CO₂ Transcritical Direct-cooling Ice Making System dynamic high-precision construction measurement green construction National Speed Skating Oval

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Evaluation of measurement uncertainty of the high-speed variable-slit system based on the Monte Carlo

Yin ZHANG, Jianwei WU, Kunpeng XING, Zhongpu WEN, Jiubin TAN

《机械工程前沿（英文）》 2020年第15卷第4期页码 517-537 doi: 10.1007/s11465-020-0589-z

摘要： This paper presents a dynamic and static error transfer model and uncertainty evaluation method for a high-speed variable-slit system based on a two-dimensional orthogonal double-layer air-floating guide rail structure. The motion accuracy of the scanning blade is affected by both the moving component it is attached to and the moving component of the following blade during high-speed motion. First, an error transfer model of the high-speed variable-slit system is established, and the influence coefficients are calculated for each source of error associated with the accuracy of the blade motion. Then, the maximum range of each error source is determined by simulation and experiment. Finally, the uncertainty of the blade displacement measurement is evaluated using the Monte Carlo method. The proposed model can evaluate the performance of the complex mechanical system and be used to guide the design.

关键词： air-floating guide rail error transfer model driving and following structure dynamic error uncertainty evaluation Monte Carlo method