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Improving the performances of ultrasonic motors using intermittent contact scheme

Jiamei JIN, Jianhui ZHANG, Fu QIAN, Zhenfeng PAN,

《机械工程前沿（英文）》 2010年第5卷第2期页码 242-246 doi: 10.1007/s11465-010-0016-y

摘要： Most ultrasonic motors operate in intermittent contact scheme. Their stators drive the rotors (or sliders) when the stators contact the rotors, and the rotors (or sliders) move under an inertia force when the stators and the rotors are separated. The duty cycle of the contact and the “flight” manages motors’ output performance. To obtain a large output force or output velocity, this paper proposes a concept using the alternative work of a multi-stator or the multi-driving end of a single stator. The method can avoid larger noise, poor efficiency, and lifetime of motors. A novel linear ultrasonic motor using the alternative work of the multi-driving end of a single stator was fabricated and investigated experimentally. The traveling speed without load of the slider is 88 mm/s, and the maximum load is 0.32 N.

关键词： ultrasonic motor intermittent contact alternative work

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非连续接触下滚圈的接触压力及疲劳寿命预测

时彧,肖友刚,雷先明

《中国工程科学》 2006年第8卷第7期页码 54-57

摘要：

建立了非连续接触下筒体-滚圈接触压力的计算模型，得出了滚圈弯矩及弯曲应力计算公式。应用名义应力法和局部应力应变法，建立了滚圈疲劳寿命预测模型。通过实例分析，得出了如下结论：通过调窑，将滚圈的最大支承载荷控制在2500kN以内，能显著提高滚圈的疲劳寿命；在传统设计中，将滚圈支承角定为30°不合理；存在一个最佳滚圈支承角，此时滚圈疲劳寿命最大。

关键词：滚圈接触压力支承角疲劳寿命

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Synthesis of Intermittent-Motion Linkages with Slight Difference in Length Between Links

CHEN Xin-bo, YU Zhen

《机械工程前沿（英文）》 2006年第1卷第1期页码 76-79 doi: 10.1007/s11465-005-0007-6

摘要：

The design of intermittent-motion linkages using traditional methods is usually complicated. In this paper, (1) a new method for realizing intermittent motion, using linkages with a slight difference in length between links, is studied; (2) some new types of intermittent-motion linkages and their software for visual analysis and design are developed; and (3) influences of some design parameters on intermittent-motion characteristics are clarified. Results confirmed that the theory and the software are useful, making the synthesis of intermittent-motion linkages clear and easy.

关键词： synthesis useful intermittent intermittent-motion traditional

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物料与窑壁间歇接触对回转窑传热过程的强化效应

雷先明,肖友刚

《中国工程科学》 2006年第8卷第8期页码 39-44

摘要：

根据回转窑内物料颗粒的运动特点，推导了颗粒团在贴壁运动过程中的非稳态导热系数及界面处的接触传热系数，进而得出了物料与封盖窑壁间的换热系数；结合已有研究成果，建立了回转窑的传热数学模型。计算表明，未考虑物料与窑壁间歇接触对回转窑传热过程的强化效应时，物料温度偏低；温度越高，强化效应对物料温度的影响越大；考虑物料与窑壁间歇接触对回转窑传热过程的强化效应，有利于提高回转窑煅烧熟料的质量和热效率。

关键词：物料封盖传热过程强化效应

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An approach for evaluating the impact of an intermittent renewable energy source on transmission expansion

Rongrit CHATTHAWORN,Surachai CHAITUSANEY

《信息与电子工程前沿（英文）》 2015年第16卷第10期页码 871-882 doi: 10.1631/FITEE.1500049

摘要： We propose a new robust optimization approach to evaluate the impact of an intermittent renewable energy source on transmission expansion planning (TEP). The objective function of TEP is composed of the investment cost of the transmission line and the operating cost of conventional generators. A method to select suitable scenarios representing the intermittent renewable energy generation and loads is proposed to obtain robust expansion planning for all possible scenarios. A meta-heuristic algorithm called adaptive tabu search (ATS) is employed in the proposed TEP. ATS iterates between the main problem, which minimizes the investment and operating costs, and the subproblem, which minimizes the cost of power generation from conventional generators and curtailments of renewable energy generation and loads. The subproblem is solved by nonlinear programming (NLP) based on an interior point method. Moreover, the impact of an intermittent renewable energy source on TEP was evaluated by comparing expansion planning with and without consideration of a renewable energy source. The IEEE Reliability Test System 79 (RTS 79) was used for testing the proposed method and evaluating the impact of an intermittent renewable energy source on TEP. The results show that the proposed robust optimization approach provides a more robust solution than other methods and that the impact of an intermittent renewable energy source on TEP should be considered.

关键词： Adaptive tabu search Renewable energy generation Robust optimization Transmission expansion planning

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Thin-liquid-film evaporation at contact line

Hao WANG, Zhenai PAN, Zhao CHEN

《能源前沿（英文）》 2009年第3卷第2期页码 141-151 doi: 10.1007/s11708-009-0020-2

摘要： When a liquid wets a solid wall, the extended meniscus near the contact line may be divided into three regions: a nonevaporating region, where the liquid is adsorbed on the wall; a transition region or thin-film region, where effects of long-range molecular forces (disjoining pressure) are felt; and an intrinsic meniscus region, where capillary forces dominate. The thin liquid film, with thickness from nanometers up to micrometers, covering the transition region and part of intrinsic meniscus, is gaining interest due to its high heat transfer rates. In this paper, a review was made of the researches on thin-liquid-film evaporation. The major characteristics of thin film, thin-film modeling based on continuum theory, simulations based on molecular dynamics, and thin-film profile and temperature measurements were summarized.

关键词： meniscus thin film contact line disjoining pressure evaporation

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Modelling of dynamic contact length in rail grinding process

null

《机械工程前沿（英文）》 2014年第9卷第3期页码 242-248 doi: 10.1007/s11465-014-0305-y

摘要：

Rails endure frequent dynamic loads from the passing trains for supporting trains and guiding wheels. The accumulated stress concentrations will cause the plastic deformation of rail towards generating corrugations, contact fatigue cracks and also other defects, resulting in more dangerous status even the derailment risks. So the rail grinding technology has been invented with rotating grinding stones pressed on the rail with defects removal. Such rail grinding works are directed by experiences rather than scientifically guidance, lacking of flexible and scientific operating methods. With grinding control unit holding the grinding stones, the rail grinding process has the characteristics not only the surface grinding but also the running railway vehicles. First of all, it’s important to analyze the contact length between the grinding stone and the rail, because the contact length is a critical parameter to measure the grinding capabilities of stones. Moreover, it’s needed to build up models of railway vehicle unit bonded with the grinding stone to represent the rail grinding car. Therefore the theoretical model for contact length is developed based on the geometrical analysis. And the calculating models are improved considering the grinding car’s dynamic behaviors during the grinding process. Eventually, results are obtained based on the models by taking both the operation parameters and the structure parameters into the calculation, which are suitable for revealing the process of rail grinding by combining the grinding mechanism and the railway vehicle systems.

关键词： rail grinding contact length dynamic model Hamiltonian system grinding stone rail grinding car

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Computation and investigation of mode characteristics in nonlinear system with tuned/mistuned contact

Houxin SHE, Chaofeng LI, Qiansheng TANG, Hui MA, Bangchun WEN

《机械工程前沿（英文）》 2020年第15卷第1期页码 133-150 doi: 10.1007/s11465-019-0557-7

摘要： This study derived a novel computation algorithm for a mechanical system with multiple friction contact interfaces that is well-suited to the investigation of nonlinear mode characteristic of a coupling system. The procedure uses the incremental harmonic balance method to obtain the nonlinear parameters of the contact interface. Thereafter, the computed nonlinear parameters are applied to rebuild the matrices of the coupling system, which can be easily solved to calculate the nonlinear mode characteristics by standard iterative solvers. Lastly, the derived method is applied to a cycle symmetry system, which represents a shaft–disk–blade system subjected to dry friction. Moreover, this study analyzed the effects of the tuned and mistuned contact features on the nonlinear mode characteristics. Numerical results prove that the proposed method is particularly suitable for the study of nonlinear characteristics in such nonlinear systems.

关键词： coupling vibration nonlinear mode original algorithm contact interface

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Transient analysis of thermoelastic contact problem of disk brakes

Ali BELHOCINE, Mostefa BOUCHETARA

《机械工程前沿（英文）》 2013年第8卷第2期页码 150-159 doi: 10.1007/s11465-013-0266-6

摘要：

The main purpose of this study is to analyze the thermomechanical behavior of the dry contact between the brake disk and pads during the braking phase. The simulation strategy is based on computer code ANSYS11. The modeling of transient temperature in the disk is actually used to identify the factor of geometric design of the disk to install the ventilation system in vehicles. The thermal-structural analysis is then used with coupling to determine the deformation established and the Von Mises stresses in the disk, the contact pressure distribution in pads. The results are satisfactory compared to those found in the literature.

关键词： brake disks heat flux heat-transfer coefficient Von Mises stress contact pressure

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Experimental study and numerical simulation on compressive buckling behavior of thin steel skins in unilateral contact

Nicholas KEAGE, Christopher MAIOLO, Rebecca PIEROTTI, Xing MA

《结构与土木工程前沿（英文）》 2011年第5卷第3期页码 335-343 doi: 10.1007/s11709-011-0121-y

摘要： In this paper, a practical test and finite element analysis has been undertaken to further investigate the effects of contact buckling. A test rig was designed and constructed to record vertical and transverse deflections of compressively loaded steel skin plates. The boundary conditions were modeled as fully fixed. A finite element analysis was also undertaken using the software package Strand7. Results from both analyses have been examined and compared to data established from previous studies on contact buckling. Both the finite element analysis and practical results correlate well with this data. The result of the investigation has confirmed contact buckling theories and has foreshadowed the onset of the newly observed phenomenon of secondary contact buckling.

关键词： compressive buckling thin steel skins unilateral contact rigid constraints

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Performance of a hybrid anaerobic-contact oxidation biofilm baffled reactor for the treatment of decentralized

Minmin LIU,Ying ZHAO,Beidou XI,Li’an HOU,Xunfeng XIA

《环境科学与工程前沿（英文）》 2014年第8卷第4期页码 598-606 doi: 10.1007/s11783-013-0576-2

摘要： A novel hybrid anaerobic-contact oxidation biofilm baffled reactor (HAOBR) was developed to simultaneously remove nitrogenous and carbonaceous organic pollutants from decentralized molasses wastewater in the study. The study was based on the inoculation of anaerobic granule sludge in anaerobic compartments and the installation of combination filler in aerobic compartments. The performance of reactor system was studied regarding the hydraulic retention time (HRT), microbial characteristics and the gas water ratio (GWR). When the HRT was 24h and the GWR was 20:1, total ammonia and chemical oxygen demand (COD) of the effluent were reduced by 99% and 91.8%, respectively. The reactor performed stably for treating decentralized molasses wastewater. The good performance of the reactor can be attributed to the high resistance of COD and hydraulic shock loads. In addition, the high solid retention time of contact oxidation biofilm contributed to stable performance of the reactor.

关键词： combination filler contact oxidation biofilm food wastewater anaerobic baffled reactor

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A fast compound direct iterative algorithm for solving transient line contact elastohydrodynamic lubrication

null

《机械工程前沿（英文）》 2014年第9卷第2期页码 156-167 doi: 10.1007/s11465-014-0297-7

摘要：

A fast compound direct iterative algorithm for solving transient line contact elastohydrodynamic lubrication (EHL) problems is presented. First, by introducing a special matrix splitting iteration method into the traditional compound direct iterative method, the full matrices for the linear systems of equations are transformed into sparse banded ones with any half-bandwidth; then, an extended Thomas method which can solve banded linear systems with any half-bandwidth is derived to accelerate the computing speed. Through the above two steps, the computational complexity of each iteration is reduced approximately from O(N3/3) to O(β2N), where N is the total number of nodes, and β is the half-bandwidth. Two kinds of numerical results of transient EHL line contact problems under sinusoidal excitation or pure normal approach process are obtained. The results demonstrate that the new algorithm increases computing speed several times more than the traditional compound direct iterative method with the same numerical precision. Also the results show that the new algorithm can get the best computing speed and robustness when the ratio, half-bandwidth to total number of nodes, is about 7.5%–10.0% in moderate load cases.

关键词： elastohydrodynamic lubrication transient line contact matrix splitting iteration method the Thomas method

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Calculating frictional force with considering material microstructure and potential on contact surfaces

XU Zhongming, HUANG Ping

《机械工程前沿（英文）》 2007年第2卷第4期页码 474-477 doi: 10.1007/s11465-007-0082-y

摘要： A method based on the energy dissipation mechanism of an Independent Oscillator model is used to calculate the frictional force and the friction coefficient of interfacial friction. The friction work is calculated with considering the potential change of contact surfaces during sliding. The potential change can be gained by a universal adhesive energy function. The relationships between frictional force and parameters of a tribo-system, such as surface energy and microstructure of interfacial material, are set up. The calculation results of the known experimental data denote that the frictional force is nearly proportional to the surface energy of the material, nearly inversely proportional to the scaling length, and independent of the lattice constant. The results agree with that of adhesion friction equations. They also agree with the experimental results performed with an atomic-force microscope under the ultra high vacuum condition.

关键词： coefficient dissipation mechanism universal adhesive interfacial Independent Oscillator

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Contact of surfaces and contact characteristics of offset surfaces

CAO Lixin, GONG Hu, LIU Jian

《机械工程前沿（英文）》 2008年第3卷第3期页码 318-324 doi: 10.1007/s11465-008-0067-5

摘要： Based on differential geometry, the contact problems of two surfaces are discussed in this paper. The relationship between the contact status of two surfaces and that of offset surfaces are also analyzed. For a 5-axis NC machining, some research such as optimization of cutter location and calculation of the geometrical cusp height are important. The research results indicate that the relative normal curvature is an important geometrical invariant for describing the contact state of two surfaces. For point contact two surfaces, the calculation equation for the second order remained error is given. For line contact two surfaces, the condition of the second order line contact is that the principal directions and curvatures of the two surfaces are the same along the contact curve. If two surfaces keep the second order line contact, their two offset surfaces will also keep the second order line contact, and their third order remained errors are also uniform with that of the two offset surfaces.

关键词： relative important geometrical relationship geometrical invariant calculation

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Experimental and numerical study on microcrack detection using contact nonlinear acoustics

Xiaojia CHEN, Yuanlin WANG

《结构与土木工程前沿（英文）》 2009年第3卷第2期页码 137-141 doi: 10.1007/s11709-009-0028-z

摘要： This paper introduces a non-classical nonlinear acoustic theory for microcrack detection in materials, comparing contact nonlinearity with material nonlinearity. The paper’s main work concentrates on the experimental and numerical verification of the effectivity of contact nonlinear acoustic detection by using the contact nonlinear parameter , which can be represented by the ratio of the second-harmonic amplitude to the square of the first-harmonic amplitude. Both experiments and numerical tests are performed. The results show that is sensitive to the initiation of microcracks and varies with the development of the microcracks. The numerical test illustrates the decline of when microcracks penetrate each other.

关键词： microcrack detection contact nonlinearity numerical analysis