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关键词

可编程超表面 2

CP）；符号间干扰（inter symbol interference， ISI）；载波间干扰（inter carrier interference 1

ICI）；最大似然估计（maximum likelihood estimation 1

IHNI 1

MLE） 1

OFDM）；快速傅立叶变换（Fast Fourier transform， FFT）；循环前缀（cyclic prefix 1

PGNAA 1

RNA干扰（RNAi） 1

SARS-CoV-2干扰 1

Z干扰信道；非正则信号；和速率；帕累托边界；协方差；伪协方差 1

三峡升船机 1

主动控制 1

仿生学 1

传输性能分析模型 1

佩戴口罩 1

侧边曲线方程 1

信息作战 1

信息流分析；业务流程执行语言；Petri网；干扰性 1

冷原子绝对重力探测 1

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cross-linked MXene/cellulose nanofiber/nickel alginate film with improved mechanical properties and electromagneticinterference shielding performance

《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： Ti3C2Tx MXene     double crosslinking     mechanical properties     EMI shielding performance    

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aerogels decorated with multi-walled carbon nanotubes: preparation, characterization, and application for electromagneticinterference 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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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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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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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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Elastoplastic frictional contact problem study on interference fits of compressor

ZHANG Hongwu, WU Changhua, LIAO Aihua

《能源前沿（英文）》 2008年 第2卷 第3期   页码 313-319 doi: 10.1007/s11708-008-0026-1

摘要： The FE parametric quadratic programming (PQP) method developed from the parametric variational principle (PVP) was used for the analysis of the stress distribution of the 3D elastoplastic frictional contact of an impeller-shaft sleeve-shaft. A locomotive-type turbocharger compressor with 24 blades under combined centrifugal and interference-fit loading was considered in the numerical analysis. The solution of elastoplastic frictional contact problems belongs to unspecified boundary problems where the interaction between two kinds of nonlinearities should occur. To save time in the numerical computation, a multi-substructure technique was adopted in the structural modeling. The effect of fit tolerance, wall thickness of the shaft sleeve, and rotational speed on the contact stress was discussed in detail in the numerical computation. To decrease the difficulty of the assembly process and ensure the safety of the working state, the amount of interference between the shaft sleeve and shaft by press-fitting should be controlled strictly to avoid the rapid increase of contact stress. The numerical results show that the algorithm has high accuracy and good convergence. The study can be referred to in deciding the proper fit tolerance and improving the design and manufacturing technology of compressor impellers.

关键词： computation     thickness     interference-fit     interference     unspecified    

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Laser interference fabrication of large-area functional periodic structure surface

Lei WANG, Zi-Han WANG, Yan-Hao YU, Hong-Bo SUN

《机械工程前沿（英文）》 2018年 第13卷 第4期   页码 493-503 doi: 10.1007/s11465-018-0507-9

摘要：

Functional periodic structures have attracted significant interest due to their natural capabilities in regulating surface energy, surface effective refractive index, and diffraction. Several technologies are used for the fabrication of these functional structures. The laser interference technique in particular has received attention because of its simplicity, low cost, and high-efficiency fabrication of large-area, micro/nanometer-scale, and periodically patterned structures in air conditions. Here, we reviewed the work on laser interference fabrication of large-area functional periodic structures for antireflection, self-cleaning, and superhydrophobicity based on our past and current research. For the common cases, four-beam interference and multi-exposure of two-beam interference were emphasized for their setup, structure diversity, and various applications for antireflection, self-cleaning, and superhydrophobicity. The relations between multi-beam interference and multi-exposure of two-beam interference were compared theoretically and experimentally. Nanostructures as a template for growing nanocrystals were also shown to present future possible applications in surface chemical control. Perspectives on future directions and applications for laser interference were presented.

关键词： laser interference     four-beam interference     multi-exposure of two-beam interference     additive fabrication    

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High heat flux thermal management through liquid metal driven with electromagnetic induction pump

《能源前沿（英文）》 2022年 第16卷 第3期   页码 460-470 doi: 10.1007/s11708-022-0825-9

摘要： In this paper, a novel liquid metal-based minichannel heat dissipation method was developed for cooling electric devices with high heat flux. A high-performance electromagnetic induction pump driven by rotating permanent magnets is designed to achieve a pressure head of 160 kPa and a flow rate of 3.24 L/min, which could enable the liquid metal to remove the waste heat quickly. The liquid metal-based minichannel thermal management system was established and tested experimentally to investigate the pumping capacity and cooling performance. The results show that the liquid metal cooling system can dissipate heat flux up to 242 W/cm2 with keeping the temperature rise of the heat source below 50°C. It could remarkably enhance the cooling performance by increasing the rotating speed of permanent magnets. Moreover, thermal contact resistance has a critical importance for the heat dissipation capacity. The liquid metal thermal grease is introduced to efficiently reduce the thermal contact resistance (a decrease of about 7.77 × 10−3 °C/W). This paper provides a powerful cooling strategy for thermal management of electric devices with large heat power and high heat flux.

关键词： high heat flux     liquid metal     electromagnetic pump     minichannel heat sink     thermal interface material    

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Review on electromagnetic welding of dissimilar materials

K. SHANTHALA,T. N. SREENIVASA

《机械工程前沿（英文）》 2016年 第11卷 第4期   页码 363-373 doi: 10.1007/s11465-016-0375-0

摘要：

Electromagnetic welding (EMW) is a high-speed joining technique that is used to join similar or dissimilar metals, as well as metals to non-metals. This technique uses electromagnetic force to mainly join conductive materials. Unlike conventional joining processes, the weld interface does not melt, thus keeping the material properties intact. Extremely high velocity and strain rate involved in the process facilitate extending the EMW technique for joining several materials. In this paper, the research and progress in electromagnetic welding are reviewed from various perspectives to provide a basis for further research.

关键词： electromagnetic     welding     impact     dissimilar materials    

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Construction and identification of lentiviral RNA interference vector of rat leptin receptor gene

Zhengjuan LIU, Jie BIAN, Yuchuan WANG, Yongli ZHAO, Dong YAN, Xiaoxia WANG

《医学前沿（英文）》 2009年 第3卷 第1期   页码 57-60 doi: 10.1007/s11684-009-0003-z

摘要： Leptin resistance is a main mechanism of acquired childhood obesity, and the suppression of long form of leptin receptor (OBRb) gene expression in diet-induced obese rats indicates that the down-regulation of OBRb gene expression plays a pivotal role in the mechanism of leptin resistance. The aim of the present study was to construct the lentiviral RNA interference (RNAi) vector of rat OBRb gene and evaluate the effects of siRNA on silencing OBRb gene expression. The target sequence of siRNA-OBRb was designed, and the complementary DNA containing both sense and antisense oligonucleotides was synthesized. After phosphorylation and annealing, these double-stranded DNA was cloned to pRNA-lentivector-VGFP to construct pRNA-Lenti-OBRb-VGFP recombinants with U6-containing promoter, target sequence and Poly III terminator. Then, the products were confirmed by electrophoresis and sequencing analysis, and the effects of RNAi on reducing gene expression were further confirmed by real-time polymerase chain reaction in transfected rat glioma cells expressing OBRb. The target sequence of siRNA-OBRb was successfully cloned to pRNA-lentivector-VGFP, and the RNAi protocol specifically reduced the expression of OBRb mRNA by approximately 80% compared with controls in transfected rat glioma cells. The successful construction of rat lentivirus vectors expressing OBRb-specific shRNA may be useful for further investigation .

关键词： receptors     leptin     RNA interference     lentivirus vector    

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Experimental study of aerodynamic interference effects on aerostatic coefficients of twin deck bridges

Zhiwen LIU , Zhengqing CHEN , Gao LIU , Xinpeng SHAO ,

《结构与土木工程前沿（英文）》 2009年 第3卷 第3期   页码 292-298 doi: 10.1007/s11709-009-0048-8

摘要： The aerodynamic interference effects on aerostatic coefficients of twin deck bridges with large span were investigated in detail by means of wind tunnel test. The distances between the twin decks and wind attack angles were changed during the wind tunnel test to study the effects on aerodynamic interferences of aerostatic coefficients of twin decks. The research results have shown that the drag coefficients of the leeward deck are much smaller than that of a single leeward deck. The drag coefficients of a windward deck decrease slightly compared with that of a single deck. The lift and torque coefficients of windward and leeward decks are also affected slightly by the aerodynamic interference of twin decks. And the aerodynamic interference effects on lift and torque coefficients of twin decks can be neglected.

关键词： twin decks     aerodynamic interference effects     aerostatic coefficients     wind tunnel test    

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Calculation method of radial stress and deformation on conic threaded connections with interference fit

Shoujun CHEN, Qiang LI, Qi AN,

《机械工程前沿（英文）》 2010年 第5卷 第3期   页码 302-307 doi: 10.1007/s11465-010-0018-9

摘要： This paper presents a calculation method for radial stress distribution and deformation on conic threaded connections with interference fit. Based on elastic mechanics, a new calculation model is established using the thick-walled-cylindrical theory. A sample calculation for API 88.9 mm conic threaded connection indicates that the method proposed in this paper is reasonable, and the finite element analysis (FEA) method is used to validate the proposed method. The results obtained by the proposed method and FEA method are identical. The model offers a new way of calculating the radial stress and deformation on conic thread connections with interference fit.

关键词： conic threaded connections     interference fit     radial stress     deformation     finite element analysis (FEA)    

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Radial electromagnetic type unbalance vibration self-recovery regulation system for high-end grinding

《机械工程前沿（英文）》 2023年 第18卷 第3期 doi: 10.1007/s11465-023-0763-1

摘要： Modern rotating machines, which are represented by high-end grinding machines, have developed toward high precision, intelligence, and high durability in recent years. As the core components of grinding machine spindles, grinding wheels greatly affect the vibration level during operation. The unbalance vibration self-recovery regulation (UVSRR) system is proposed to suppress the vibration of grinding wheels during workpiece processing, eliminating or minimizing the imbalance. First, technical principles and the system composition are introduced. Second, the balancing actuator in the UVSRR system is analyzed in detail. The advanced nature of the improved structure is presented through structure introduction and advantage analysis. The performance of the balancing actuator is mutually verified by the theoretical calculation of torque and software simulation. Results show that the self-locking torque satisfies the actual demand, and the driving torque is increased by 1.73 times compared with the traditional structure. Finally, the engineering application value of the UVSRR system is verified by laboratory performance comparison and actual factory application. The balancing speed and effect of the UVSRR system are better than those of an international mainstream product and, the quality of the workpieces machined in the factory improved by 40%.

关键词： UVSRR system     radial electromagnetic type     vibration suppression     performance simulation     engineering application    

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Design of packing cup interference fit value of hypercompressors for low density polyethylene production

Da LEI,Xuehong LI,Yun LI,Xiwen REN

《能源前沿（英文）》 2019年 第13卷 第1期   页码 107-113 doi: 10.1007/s11708-017-0450-1

摘要： The hypercompressor is one of the core facilities in low density polyethylene production, with a discharge pressure of approximately 300 MPa. A packing cup is the basic unit of cylinder packing, assembled by the interference fit between an inner cup and an outer cup. Because the shrink-fitting prestresses the packing cup, serious design is needed to gain a favorable stress state, for example, a tri-axial compressive stress state. The traditional method of designing the interference fit value for packing cups depends on the shrink-fit theory for thick-walled cylinder subject to internal and external pressure. According to the traditional method, critical points are at the inner radii of the inner and external cup. In this study, the finite element method (FEM) has been implemented to determine a more accurate stress level of packing cups. Different critical points have been found at the edge of lapped sealing surfaces between two adjacent packing cups. The maximum Von Mises equivalent stress in a packing cup increases after a decline with the rise of the interference fit value. The maximum equivalent stress initially occurs at the bore of the inner cup, then at the edge of lapped mating surfaces, and finally at the bore of the outer cup, as the interference radius increases. The traditional method neglects the influence of axial preloading on the interference mating pressure. As a result, it predicts a lower equivalent stress at the bore of the external cup. A higher interference fit value accepted by the traditional method may not be feasible as it might already make packing cups yield at the edge of mating surfaces or the bore of the external cup. Along with fatigue analysis, the feasible range of interference fit value has been modified by utilizing FEM. The modified range tends to be narrower and safer than the one derived from the traditional method, after getting rid of shrink-fit values that could result in yielding in a real packing cup.

关键词： interference fit value     packing cup     hypercompressor     finite element method (FEM)    

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Analytical model and finite element computation of braking torque in electromagnetic retarder

Lezhi YE,Guangzhao YANG,Desheng LI

《机械工程前沿（英文）》 2014年 第9卷 第4期   页码 368-379 doi: 10.1007/s11465-014-0314-x

摘要：

An analytical model has been developed for analyzing the braking torque in electromagnetic retarder by flux tube and armature reaction method. The magnetic field distribution in air gap, the eddy current induced in the rotor and the braking torque are calculated by the developed model. Two-dimensional and three-dimensional finite element models for retarder have also been developed. Results from the analytical model are compared with those from finite element models. The validity of these three models is checked by the comparison of the theoretical predictions and the measurements from an experimental prototype. The influencing factors of braking torque have been studied.

关键词： electromagnetic retarder     magnetic field distribution     magnetic circuit     finite element method    

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标题 作者 时间 类型 操作

cross-linked MXene/cellulose nanofiber/nickel alginate film with improved mechanical properties and electromagneticinterference shielding performance

期刊论文

aerogels decorated with multi-walled carbon nanotubes: preparation, characterization, and application for electromagneticinterference shielding

Jian LI,Caichao WAN

期刊论文

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

期刊论文

用于电热转换、电磁屏蔽的导电陶瓷的简易大规模制备

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

期刊论文

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

Le YANG, Shuo WANG, Jianghua FENG

期刊论文

Elastoplastic frictional contact problem study on interference fits of compressor

ZHANG Hongwu, WU Changhua, LIAO Aihua

期刊论文

Laser interference fabrication of large-area functional periodic structure surface

Lei WANG, Zi-Han WANG, Yan-Hao YU, Hong-Bo SUN

期刊论文

High heat flux thermal management through liquid metal driven with electromagnetic induction pump

期刊论文

Review on electromagnetic welding of dissimilar materials

K. SHANTHALA,T. N. SREENIVASA

期刊论文

Construction and identification of lentiviral RNA interference vector of rat leptin receptor gene

Zhengjuan LIU, Jie BIAN, Yuchuan WANG, Yongli ZHAO, Dong YAN, Xiaoxia WANG

期刊论文

Experimental study of aerodynamic interference effects on aerostatic coefficients of twin deck bridges

Zhiwen LIU , Zhengqing CHEN , Gao LIU , Xinpeng SHAO ,

期刊论文

Calculation method of radial stress and deformation on conic threaded connections with interference fit

Shoujun CHEN, Qiang LI, Qi AN,

期刊论文

Radial electromagnetic type unbalance vibration self-recovery regulation system for high-end grinding

期刊论文

Design of packing cup interference fit value of hypercompressors for low density polyethylene production

Da LEI,Xuehong LI,Yun LI,Xiwen REN

期刊论文

Analytical model and finite element computation of braking torque in electromagnetic retarder

Lezhi YE,Guangzhao YANG,Desheng LI

期刊论文