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nanofiber/nickel alginate film with improved mechanical properties and electromagnetic interference shieldingperformance

《化学科学与工程前沿（英文）》 2023年第17卷第10期页码 1460-1469 doi: 10.1007/s11705-023-2335-7

摘要： Electromagnetic interference pollution has raised urgent demand for the development of electromagnetic interference shielding materials. Transition metal carbides (MXenes) with excellent conductivity have shown great potential in electromagnetic interference (EMI) shielding materials, while the poor mechanical strength, flexibility, and structural stability greatly limit their further applications. Here, cellulose nanofibers and sodium alginate are incorporated with MXene nanosheets as flexible matrices to construct strong and flexible mussel-like layered MXene/Cellulose nanofiber/Sodium Alginate composite films, and nickel ions are further introduced to induce metal coordination crosslinking of alginate units. Benefited from the dual-crosslinked network structure of hydrogen bonding and metal coordination, the tensile strength, Young’s modulus, and toughness of the MXene/cellulose nanofiber/nickel alginate composite film are significantly increased. After subsequent reduction by ascorbic acid, excess nickel ions are reduced to nickel nanoparticles and uniformly dispersed within the highly conductive composite film, which further improved its hysteresis loss effect toward the incident electromagnetic waves. Consequently, the MXene/cellulose nanofiber/nickel alginate-Ni composite film presents a considerably enhanced electromagnetic interference shielding effectiveness (47.17 dB) at a very low thickness of 29 μm. This study proposes a feasible dual-crosslinking and subsequent reduction strategy to synergistically enhance the mechanical properties and electromagnetic interference shielding performance of MXene-based composite materials.

关键词： Ti₃C₂T_x MXene double crosslinking mechanical properties EMI shielding performance

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Electromagnetic interference modeling and suppression techniques in variable-frequency drive systems

Le YANG, Shuo WANG, Jianghua FENG

《机械工程前沿（英文）》 2018年第13卷第3期页码 329-353 doi: 10.1007/s11465-018-0466-1

摘要：

Electromagnetic interference (EMI) causes electromechanical damage to the motors and degrades the reliability of variable-frequency drive (VFD) systems. Unlike fundamental frequency components in motor drive systems, high-frequency EMI noise, coupled with the parasitic parameters of the trough system, are difficult to analyze and reduce. In this article, EMI modeling techniques for different function units in a VFD system, including induction motors, motor bearings, and rectifier-inverters, are reviewed and evaluated in terms of applied frequency range, model parameterization, and model accuracy. The EMI models for the motors are categorized based on modeling techniques and model topologies. Motor bearing and shaft models are also reviewed, and techniques that are used to eliminate bearing current are evaluated. Modeling techniques for conventional rectifier-inverter systems are also summarized. EMI noise suppression techniques, including passive filter, Wheatstone bridge balance, active filter, and optimized modulation, are reviewed and compared based on the VFD system models.

关键词： variable-frequency drive (VFD) electromagnetic interference (EMI) motor drive modeling EMI noise suppression

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用于电热转换、电磁屏蔽的导电陶瓷的简易大规模制备 Article

李岱祺, 唐彬, 程德山, 吴静, 唐文杨, 赵仲, 李建强, 蔡光明, 王金凤, 王训该

《工程（英文）》 2023年第21卷第2期页码 143-151 doi: 10.1016/j.eng.2021.12.017

摘要：

通过传统瓷砖制备工艺的干压法，制备了一种碳化酚醛树脂基导电陶瓷复合材料（CCC）。首先，将导电前驱体溶液（酚醛树脂）与陶瓷前驱体均匀混合，随后在单次热处理中同时实现了碳化和陶瓷化。碳化后的材料赋予复合材料出色的电导率和可靠的循环加热特性。在12 V电压下通电10 min 后材料表面温度可达386 ℃，在20 V电压下达到400 ℃仅需48 s。红外热像图表明，热量在复合材料表面分布均匀，并且可以通过更改电路布置（串联或并联）来调节电热转换性能。此外，与普通陶瓷相比，导电陶瓷复合材料在8.2 GHz下表现出了26.2 dB的优异电磁屏蔽性能，并提升了光热转换性能。更重要的是，这种单次热处理加热生产导电陶瓷复合材料的方法成本较低，可在原有瓷砖生产线的基础上进行大规模生产。出色的电学性能促进了该陶瓷复合材料在焦耳加热（如除冰、烧水和烹饪）及电磁屏蔽中的应用。

关键词：导电陶瓷复合材料电热转换性能电磁屏蔽碳化

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Carbonized nano/microparticles for enhanced mechanical properties and electromagnetic interference shielding

Rao Arsalan KHUSHNOOD,Sajjad AHMAD,Luciana RESTUCCIA,Consuelo SPOTO,Pravin JAGDALE,Jean-Marc TULLIANI,Giuseppe Andrea FERRO

《结构与土木工程前沿（英文）》 2016年第10卷第2期页码 209-213 doi: 10.1007/s11709-016-0330-5

摘要： In the present work, carbon nano/microparticles obtained by controlled pyrolysis of peanut (PS) and hazelnut (HS) shells are presented. These materials were characterized by Raman spectroscopy and field emission-scanning electron microscopy (FE-SEM). When added to cement paste, up to 1 wt%, these materials led to an increase of the cement matrix flexural strength and of toughness. Moreover, with respect to plain cement, the total increase in electromagnetic radiation shielding effect when adding 0.5 wt% of PS or HS in cement composites is much higher in comparison to the ones reported in the literature for CNTs used in the same content.

关键词： carbon nano/microparticles green cement toughness mechanism electromagnetic shielding effect

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multi-walled carbon nanotubes: preparation, characterization, and application for electromagnetic interference shielding

Jian LI,Caichao WAN

《农业科学与工程前沿（英文）》 2015年第2卷第4期页码 341-346 doi: 10.15302/J-FASE-2015082

摘要： Electromagnetic wave pollution has attracted extensive attention because of its ability to affect the operation of electronic machinery and endanger human health. In this work, the environmentally-friendly hybrid aerogels consisting of cellulose and multi-walled carbon nanotubes (MWCNTs) were fabricated. The aerogels have a low bulk density of 58.17 mg·cm . The incorporation of MWCNTs leads to an improvement in the thermal stability. In addition, the aerogels show a high electromagnetic interference (EMI) value of 19.4 dB. Meanwhile, the absorption-dominant shielding mechanism helps a lot to reduce secondary radiation, which is beneficial to develop novel eco-friendly EMI shielding materials.

关键词： cellulose aerogels carbon nanotubes electromagnetic interference shielding composites

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Preparation of transparent BaSO

Le Fang, Qian Sun, Yong-Hong Duan, Jing Zhai, Dan Wang, Jie-Xin Wang

《化学科学与工程前沿（英文）》 2021年第15卷第4期页码 902-912 doi: 10.1007/s11705-020-1985-y

摘要： BaSO nanoparticles as important functional materials have attracted considerable research interests, due to their X-rays barrier and absorption properties. However, most of BaSO nanoparticles prepared by traditional technology are nanopowders with broad size distribution and poor dispersibility, which may greatly limit their applications. To the best of our knowledge, the synthesis of transparent BaSO nanodispersions was rarely reported. Here, we firstly present a novel and efficient method to prepare transparent and stable BaSO nanodispersions with a relatively small particle size around 10 to 17 nm using a precipitation method in a rotating packed bed (RPB), followed by a modification treatment using stearic acid. Compared with the BaSO prepared in a traditional stirred tank, the product prepared using an RPB has much smaller particle size and narrower size distribution. More importantly, by using RPB, the reaction time can be significantly decreased from 20 min to 18 s. Furthermore, the transparent BaSO -polyvinyl butyral nanocomposite films with good X-ray shielding performance can be easily fabricated. We believe that the stable BaSO nanodispersions may have a wide range of applications for transparent composite materials and coatings with X-ray shielding performance for future research.

关键词： BaSO₄ nanoparticles rotating packed bed transparent nanodispersions BaSO₄-PVB films X-ray shielding

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医院中子照射器PGNAA系统初步设计及测量

张紫竹,李立华,高集金,付金树

《中国工程科学》 2012年第14卷第8期页码 28-32

摘要：

完成了医院中子照射器（IHNI）瞬发γ中子活化分析(PGNAA)系统的初步设计，并按照设计完成系统搭建。该系统探测器屏蔽部分和中子束屏蔽部分内层均为天然LiF粉末，外层为铅屏蔽层。使用该系统进行的硼浓度测量实验结果表明，该系统可测量¹⁰B浓度为10 ppm(1 ppm=10^-6)，体积为2 mL的样品，¹⁰B元素测量灵敏度为0.822 cps(s^-1)/ppm。同时发现天然LiF粉末会在待测能区产生较高本底，影响测量精度。

关键词：硼中子俘获治疗 IHNI PGNAA 硼浓度屏蔽

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从中国首台紫外-可见光高光谱卫星仪器反演得到的高空间分辨率臭氧廓线 Article

Fei Zhao, Cheng Liu, Qihou Hu, Congzi Xia, Chengxin Zhang, Wenjing Su

《工程（英文）》 2024年第32卷第1期页码 107-116 doi: 10.1016/j.eng.2023.02.020

摘要：

Understanding the vertical distribution of ozone is crucial when assessing both its horizontal and vertical transport, as well as when analyzing the physical and chemical properties of the atmosphere. One of the most effective ways to obtain high spatial resolution ozone profiles is through satellite observations. The Environmental Trace Gases Monitoring Instrument (EMI) deployed on the Gaofen-5 satellite is the first Chinese ultraviolet-visible hyperspectral spectrometer. However, retrieving ozone profiles using backscattered radiance values measured by the EMI is challenging due to unavailable measurement errors and a low signal-to-noise ratio. The algorithm developed for the Tropospheric Monitoring Instrument did not allow us to retrieve 87% of the EMI pixels. Therefore, we developed an algorithm specific to the characteristics of the EMI. The fitting residuals are smaller than 0.3% in most regions. The retrieved ozone profiles were in good agreement with ozonesonde data, with maximum mean biases of 20% at five latitude bands. By applying EMI averaging kernels to the ozonesonde profiles, the integrated stratospheric column ozone and tropospheric column ozone also showed excellent agreement with ozonesonde data. The lower layers (0–7.5 km) of the EMI ozone profiles reflected the seasonal variation in surface ozone derived from the China National Environmental Monitoring Center (CNEMC). However, the upper layers (9.7–16.7 km) of the ozone profiles show different trends, with the ozone peak occurring at an altitude of 9.7–16.7 km in March. A stratospheric intrusion event in central China from August 11 to 15, 2019, is captured using the EMI ozone profiles, potential vorticity data, and relative humidity data. The increase in the CNEMC ozone concentration showed that downward transport enhanced surface ozone pollution.

关键词： Ozone profiles EMI Soft calibration Floor noise correction Stratospheric ozone intrusion

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Performance-based and performance-driven architectural design and optimization

Xing SHI

《结构与土木工程前沿（英文）》 2010年第4卷第4期页码 512-518 doi: 10.1007/s11709-010-0090-6

摘要： As the architecture, engineering, and construction (AEC) industry is marching into the sustainable and low-carbon era, the performance of architecture has drawn more attention than ever. Simulation technology has made quantified analysis of architectural performance possible and, therefore, directly enables architects and engineers to incorporate performance analysis into the design work flow. It is argued that performance-based and performance-driven architectural designs differ in that the latter involves computer-aided optimization technique so that the performance can be used as the criteria to truly “drive” the design. The paper starts with a brief introduction of performance issues in architectural design, followed by a review of the evolution of performance-based architectural design. The concept of performance-driven architectural design is presented, and some design projects and research work are reviewed. The driving engine, i.e., optimization technique, and its application in architectural design is discussed. Challenges to making performance-driven design a common practice are explained, and a schematic of integrated performance-based/driven architectural design software is proposed.

关键词： performance optimization architectural design simulation sustainability

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基于分形图案蚀刻屏蔽金属提高磁耦合能量传输效率

Qing-feng LI,Shao-bo CHEN,Wei-ming WANG,Hong-wei HAO,Lu-ming LI

《信息与电子工程前沿（英文）》 2016年第17卷第1期页码 74-82 doi: 10.1631/FITEE.1500114

摘要：薄金属板通常位于磁耦合能量传输（MCET）系统的耦合路径中。金属中的涡流会降低能量传输效率，甚至可能带来安全隐患。本文介绍了在金属中使用蚀刻的分形图案来抑制涡流并提高效率。仿真和实验结果表明该方法非常有效。分形图案应满足三个特征，即，破坏金属边缘，在高强度磁场区域中进行蚀刻以及在厚度方向上贯穿金属进行蚀刻。不同的分形模式导致不同的结果。通过改变涡流分布，当金属表现出电阻效应时，分形图案槽可减少涡流损耗，而当金属表现出电感效应时，分形图案槽可抑制金属中的感应磁场。多层高电导率金属（例如Cu）中的分形图案缝隙显着降低了感应磁场强度。此外，随着蚀刻层数的增加，传递功率，传递效率，接收效率和涡流损耗都增加。这些结果可通过有效的能量传输和在金属屏蔽设备中的安全使用而使MCET受益。

关键词：分形几何；层状金属屏蔽；涡流效应；磁耦合能量传输

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Flexural and longitudinal shear performance of precast lightweight steel–ultra-high performance concrete

《结构与土木工程前沿（英文）》 2023年第17卷第5期页码 704-721 doi: 10.1007/s11709-023-0941-6

摘要： In this study, the flexural and longitudinal shear performances of two types of precast lightweight steel–ultra-high performance concrete (UHPC) composite beams are investigated, where a cluster UHPC slab (CUS) and a normal UHPC slab (NUS) are connected to a steel beam using headed studs through discontinuous shear pockets and full-length shear pockets, respectively. Results show that the longitudinal shear force of the CUS is greater than that of the NUS, whereas the interfacial slip of the former is smaller. Owing to its better integrity, the CUS exhibits greater flexural stiffness and a higher ultimate bearing capacity than the NUS. To further optimize the design parameters of the CUS, a parametric study is conducted to investigate their effects on the flexural and longitudinal shear performances. The square shear pocket is shown to be more applicable for the CUS, as the optimal spacing between two shear pockets is 650 mm. Moreover, a design method for transverse reinforcement is proposed; the transverse reinforcement is used to withstand the splitting force caused by studs in the shear pocket and prevent the UHPC slab from cracking. According to calculation results, the transverse reinforcement can be canceled when the compressive strength of UHPC is 150 MPa and the volume fraction of steel fiber exceeds 2.0%.

关键词： precast steel–UHPC composite beam flexural performance longitudinal shear performance parametric study transverse reinforcement ratio

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Experimental research on cyclone performance at high temperature

LI Wenqi, CHEN Jianyi

《机械工程前沿（英文）》 2007年第2卷第3期页码 310-317 doi: 10.1007/s11465-007-0055-1

摘要： To predict the influence of operating temperatures on cyclone performance, an experimental investigation was conducted on particle separation in a reverse flow, tangential volute-inlet cyclone separator with a diameter of 300 mm and with air heated up to 973 K. The test powder silica has a mass median diameter of 10 um, while inlet velocity range was 12-36 m/s. Both the separation efficiency and pressure drop of the cyclone were measured as a function of the inlet velocity and operating temperature. At the same inlet velocity, both the separation efficiency and pressure drop decrease with increasing temperature. In addition, optimum inlet velocity, at which the cyclone has its highest separation efficiency, tends to increase with a rise in temperature. An analysis on our own data and published results has shown that the fractional efficiency of a cyclone is a definite function of dimensionless numbers such as the Stokes number, the Reynolds number, the Froude number, dimensionless cyclone inlet area, and dimensionless outlet diameter. A nondimensional experimental correlation of the cyclone performance, including the influence of temperature, was obtained on the basis of our own previous work. The prediction of the influence of temperature on separation efficiencies and pressure drops is in fairly good agreement with experimental results.

关键词： diameter definite function nondimensional experimental cyclone performance influence

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Comparison of indices for stiffness performance evaluation

Giuseppe CARBONE, Marco CECCARELLI,

《机械工程前沿（英文）》 2010年第5卷第3期页码 270-278 doi: 10.1007/s11465-010-0023-z

摘要： This paper addresses the problem of a numerical evaluation of the stiffness performance for multibody robotic systems. An overview is presented with basic formulation concerning indices that are proposed in literature. New indices are also outlined. Stiffness indices are computed and compared for a case study. Results are used for comparing the effectiveness of the stiffness indices. The main goal is to propose a performance index describing synthetically the elastostatic response of a multibody robotic system and also for design purposes.

关键词： robotics stiffness performance indices

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Performance of steel bridge deck pavement structure with ultra high performance concrete based on resin

《结构与土木工程前沿（英文）》 2021年第15卷第4期页码 895-904 doi: 10.1007/s11709-021-0759-z

摘要： This research investigated a pavement system on steel bridge decks that use epoxy resin (EP) bonded ultra-high performance concrete (UHPC). Through FEM analysis and static and dynamic bending fatigue tests of the composite structure, the influences of the interface of the pavement layer, reinforcement, and different paving materials on the structural performance were compared and analyzed. The results show that the resin bonded UHPC pavement structure can reduce the weld strain in the steel plate by about 32% and the relative deflection between ribs by about 52% under standard axial load conditions compared to traditional pavements. The EP bonding layer can nearly double the drawing strength of the pavement interface from 1.3 MPa, and improve the bending resistance of the UHPC structure on steel bridge decks by about 50%; the bending resistance of reinforced UHPC structures is twice that of unreinforced UHPC structure, and the dynamic deflection of the UHPC pavement structure increases exponentially with increasing fatigue load. The fatigue life is about 1.2 × 10⁷ cycles under a fixed force of 9 kN and a dynamic deflection of 0.35 mm, which meets the requirements for fatigue performance of pavements on steel bridge decks under traffic conditions of large flow and heavy load.

关键词： steel bridge deck pavement ultra-high-performance concrete epoxy resin composite structure bending fatigue performance

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Cutting performance of surgical electrodes by constructing bionic microstriped structures

《机械工程前沿（英文）》 2023年第18卷第1期 doi: 10.1007/s11465-022-0728-9

摘要： Surgical electrodes rely on thermal effect of high-frequency current and are a widely used medical tool for cutting and coagulating biological tissue. However, tissue adhesion on the electrode surface and thermal injury to adjacent tissue are serious problems in surgery that can affect cutting performance. A bionic microstriped structure mimicking a banana leaf was constructed on the electrode via nanosecond laser surface texturing, followed by silanization treatment, to enhance lyophobicity. The effect of initial, simple grid-textured, and bionic electrodes with different wettabilities on tissue adhesion and thermal injury were investigated using horizontal and vertical cutting modes. Results showed that the bionic electrode with high lyophobicity can effectively reduce tissue adhesion mass and thermal injury depth/area compared with the initial electrode. The formation mechanism of adhered tissue was discussed in terms of morphological features, and the potential mechanism for antiadhesion and heat dissipation of the bionic electrode was revealed. Furthermore, we evaluated the influence of groove depth on tissue adhesion and thermal injury and then verified the antiadhesion stability of the bionic electrode. This study demonstrates a promising approach for improving the cutting performance of surgical electrodes.

关键词： surgical electrodes tissue adhesion thermal injury bionic structures cutting performance medical tools