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Analysis of suitable geometrical parameters for designing a tendon-driven under-actuated mechanical finger

Francesco PENTA,Cesare ROSSI,Sergio SAVINO

《机械工程前沿（英文）》 2016年 第11卷 第2期   页码 184-194 doi: 10.1007/s11465-016-0385-y

摘要：

This study aims to optimize the geometrical parameters of an under-actuated mechanical finger by conducting a theoretical analysis of these parameters. The finger is actuated by a flexion tendon and an extension tendon. The considered parameters are the tendon guide positions with respect to the hinges. By applying such an optimization, the correct kinematical and dynamical behavior of the closing cycle of the finger can be obtained. The results of this study are useful for avoiding the snap-through and the single joint hyperflexion, which are the two breakdowns most frequently observed during experimentation on prototypes. Diagrams are established to identify the optimum values for the tendon guides position of a finger with specified dimensions. The findings of this study can serve as guide for future finger design.

关键词： tendon-driven fingers     mechanical finger design     under-actuated mechanical systems    

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Push recovery for the standing under-actuated bipedal robot using the hip strategy

Chao LI,Rong XIONG,Qiu-guo ZHU,Jun WU,Ya-liang WANG,Yi-ming HUANG

《信息与电子工程前沿（英文）》 2015年 第16卷 第7期   页码 579-593 doi: 10.1631/FITEE.14a0230

摘要： This paper presents a control algorithm for push recovery, which particularly focuses on the hip strategy when an external disturbance is applied on the body of a standing under-actuated biped. By analyzing a simplified dynamic model of a bipedal robot in the stance phase, it is found that horizontal stability can be maintained with a suitably controlled torque applied at the hip. However, errors in the angle or angular velocity of body posture may appear, due to the dynamic coupling of the translational and rotational motions. To solve this problem, different hip strategies are discussed for two cases when (1) external disturbance is applied on the center of mass (CoM) and (2) external torque is acting around the CoM, and a universal hip strategy is derived for most disturbances. Moreover, three torque primitives for the hip, depending on the type of disturbance, are designed to achieve translational and rotational balance recovery simultaneously. Compared with closed-loop control, the advantage of the open-loop methods of torque primitives lies in rapid response and reasonable performance. Finally, simulation studies of the push recovery of a bipedal robot are presented to demonstrate the effectiveness of the proposed methods.

关键词： Push recovery     Balance control     Bipedal robot     Hip strategy    

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Development of a redundant anthropomorphic hydraulically actuated manipulator with a roll–pitch–yaw spherical

《机械工程前沿（英文）》 2021年 第16卷 第4期   页码 698-710 doi: 10.1007/s11465-021-0646-2

摘要： The demand for redundant hydraulic manipulators that can implement complex heavy-duty tasks in unstructured areas is increasing; however, current manipulator layouts that remarkably differ from human arms make intuitive kinematic operation challenging to achieve. This study proposes a seven-degree-of-freedom (7-DOF) redundant anthropomorphic hydraulically actuated manipulator with a novel roll–pitch–yaw spherical wrist. A hybrid series–parallel mechanism is presented to achieve the spherical wrist design, which consists of two parallel linear hydraulic cylinders to drive the yaw/pitch 2-DOF wrist plate connected serially to the roll structure. Designed as a 1R PRRR-1S PU mechanism (“R”, “P”, “S”, and “U” denote revolute, prismatic, spherical, and universal joints, respectively; the underlined letter indicates the active joint), the 2-DOF parallel structure is partially decoupled to obtain simple forward/inverse kinematic solutions in which a closed-loop subchain “R PRR” is included. The 7-DOF manipulator is then designed, and its third joint axis goes through the spherical center to obtain closed-form inverse kinematic computation. The analytical inverse kinematic solution is drawn by constructing self-motion manifolds. Finally, a physical prototype is developed, and the kinematic analysis is validated via numerical simulation and test results.

关键词： hydraulic manipulator     inverse kinematic     redundant design     spherical wrist    

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Multiscale mechanical modeling of hydrated cement paste under tensile load using the combined DEM-MD

Yue HOU, Linbing WANG

《结构与土木工程前沿（英文）》 2017年 第11卷 第3期   页码 270-278 doi: 10.1007/s11709-017-0408-8

摘要： In this paper, a combined DEM-MD method is proposed to simulate the crack failure process of Hydrated Cement Paste (HCP) under a tensile force. A three-dimensional (3D) multiscale mechanical model is established using the combined Discrete Element Method (DEM)-Molecular Dynamics (MD) method in LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator). In the 3D model, HCP consists of discrete particles and atoms. Simulation results show that the combined DEM-MD model is computationally efficient with good accuracy in predicting tensile failures of HCP.

关键词： hydrated cement paste     multiscale     MD simulation     DEM    

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Micro-spectrophotometer based on micro electro-mechanical systems technology

ZHOU Lianqun, LI Zhenggang, WU Yihui, ZHANG Ping, XUAN Ming, JIA Hongguang

《机械工程前沿（英文）》 2008年 第3卷 第1期   页码 37-43 doi: 10.1007/s11465-008-0001-x

摘要： A new mini-spectrophotometer is developed by adopting micro-silicon-slit and micro-silicon-fixer, which are based on micro electro-mechanical systems (MEMS) technology. Both the micro-silicon-slit and the micro-silicon-fixer have their own features, such as small volume and high precision, which are laid out and analyzed later. Meantime, through the analysis of the sample cell’s optical characteristics that have some impacts on the linearity of the spectrophotometer, a relationship equation, which is about the impact of the refractive index of the sample cell and the tested medium on the variety of the transmitted light intensity and the absorbency, is put forward. When the water and the air are taken as the referenced medium, the experiments demonstrate that the difference of the refractive index of the references does not influence the correlation coefficient and the slope of the absorbency-concentration curve. The final results show that the new mini-spectrophotometer with micro-silicon-slit and micro-silicon-fixer is worked out, its correlation coefficient > 0.999, and its refractive index resolving power is better than 0.01.

关键词： mini-spectrophotometer     referenced     micro-silicon-fixer     electro-mechanical     correlation coefficient    

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Effect of land-use management systems on coupled physical and mechanical, chemical and biological soil

Rainer HORN, Winfried E. H. BLUM

《农业科学与工程前沿（英文）》 2020年 第7卷 第3期   页码 243-245 doi: 10.15302/J-FASE-2020334

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Research on the influence of contact surface constraint on mechanical properties of rock-concrete compositespecimens under compressive loads

Baoyun ZHAO, Yang LIU, Dongyan LIU, Wei HUANG, Xiaoping WANG, Guibao YU, Shu LIU

《结构与土木工程前沿（英文）》 2020年 第14卷 第2期   页码 322-330 doi: 10.1007/s11709-019-0594-7

摘要： The contact form of rock-concrete has a crucial influence on the failure characteristics of the stability of rock-concrete engineering. To study the influence of contact surface on the mechanical properties of rock-concrete composite specimens under compressive loads, the two different contact forms of rock-concrete composite specimens are designed, the mechanical properties of these two different specimens are analyzed under triaxial compressive condition, and analysis comparison on the stress-strain curves and failure forms of the two specimens is carried out. The influence of contact surface constraint on the mechanical properties of rock-concrete composite specimens is obtained. Results show that the stress and strain of rock-concrete composite specimens with contact surface constraint are obviously higher than those without. Averagely, compared with composite specimens without the contact surface, the existence of contact surface constraint can increase the axial peak stress of composite specimens by 24% and the axial peak strain by 16%. According to the characteristics of the fracture surface, the theory of microcrack development is used to explain the contact surface constraint of rock-concrete composite specimens, which explains the difference of mechanical properties between the two rock-concrete composite specimens in the experiment. Research results cannot only enrich the research content of the mechanics of rock contact, but also can serve as a valuable reference for the understanding of the corresponding mechanics mechanism of other similar composite specimens.

关键词： rock-concrete     composite specimen     contact surface     mechanical properties     failure mechanism    

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Preload characteristics identification of the piezoelectric-actuated 1-DOF compliant nanopositioning

Ruizhou WANG, Xianmin ZHANG

《机械工程前沿（英文）》 2015年 第10卷 第1期   页码 20-36 doi: 10.1007/s11465-015-0328-z

摘要：

Packaged piezoelectric ceramic actuators (PPCAs) and compliant mechanisms are attractive for nanopositioning and nanomanipulation due to their ultra-high precision. The way to create and keep a proper and steady connection between both ends of the PPCA and the compliant mechanism is an essential step to achieve such a high accuracy. The connection status affects the initial position of the terminal moving plate, the positioning accuracy and the dynamic performance of the nanopositioning platform, especially during a long-time or high-frequency positioning procedure. This paper presents a novel external preload mechanism and tests it in a 1-degree of freedom (1-DOF) compliant nanopositioning platform. The 1-DOF platform utilizes a parallelogram guiding mechanism and a parallelogram load mechanism to provide a more accurate actual input displacement and output displacement. The simulation results verify the proposed stiffness model and dynamic model of the platform. The values of the preload displacement, actual input displacement and output displacement can be measured by three capacitive sensors during the whole positioning procedure. The test results show the preload characteristics vary with different types or control modes of the PPCA. Some fitting formulas are derived to describe the preload displacement, actual input displacement and output displacement using the nominal elongation signal of the PPCA. With the identification of the preload characteristics, the actual and comprehensive output characteristics of the PPCA can be obtained by the strain gauge sensor (SGS) embedded in the PPCA.

关键词： nanopositioning     preload characteristic     packaged piezoelectric ceramic actuator     compliant mechanism    

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Hydrologic experiments and modeling of two laboratory bioretention systems under different boundary conditions

Ruifen Liu, Elizabeth Fassman-Beck

《环境科学与工程前沿（英文）》 2017年 第11卷 第4期 doi: 10.1007/s11783-017-0951-5

摘要： Hydrologic performance of bioretention systems is significantly influenced by the media composition and underdrain configuration. This research measured hydrologic performance of column-scale bioretention systems during a synthetic design storm of 25.9 mm, assuming a system area:catchment area ratio of 5%. The laboratory experiments involved two different engineered media and two different drainage configurations. Results show that the two engineered media with different sand aggregates were able to retain about 36% of the inflow volume with free drainage configuration. However, the medium with marine sand is better at delaying the occurrence of drainage than the one with pumice sand, denoting the better detention ability of the former. For both engineered media, an underdrain configuration with internal water storage (IWS) zone lowered drainage volume and peak drainage rate as well as delayed the occurrence of drainage and peak drainage rate, as compared to a free drainage configuration. The USEPA SWMM v5.1.11 model was applied for the free drainage configuration case, and there is a reasonable fit between observed and modeled drainage-rates when media-specific characteristics are available. For the IWS drainage configuration case, air entrapment was observed to occur in the engineered medium with marine sand. Filling of an IWS zone is most likely to be influenced by many factors, such as the structure of the bioretention system, medium physical and hydraulic properties, and inflow characteristics. More research is needed on the analysis and modeling of hydrologic process in bioretention with IWS drainage configuration.

关键词： Bioretention     Hydrologic process     Underdrain configuration     SWMM     Modeling    

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High performance solid-state thermoelectric energy conversion via inorganic metal halide perovskites undertailored mechanical deformation

Lifu YAN, Lingling ZHAO, Guiting YANG, Shichao LIU, Yang LIU, Shangchao LIN

《能源前沿（英文）》 2022年 第16卷 第4期   页码 581-594 doi: 10.1007/s11708-022-0831-y

摘要： Solid-state thermoelectric energy conversion devices attract broad research interests because of their great promises in waste heat recycling, space power generation, deep water power generation, and temperature control, but the search for essential thermoelectric materials with high performance still remains a great challenge. As an emerging low cost, solution-processed thermoelectric material, inorganic metal halide perovskites CsPb(I1–xBrx)3 under mechanical deformation is systematically investigated using the first-principle calculations and the Boltzmann transport theory. It is demonstrated that halogen mixing and mechanical deformation are efficient methods to tailor electronic structures and charge transport properties in CsPb(I1–xBrx)3 synergistically. Halogen mixing leads to band splitting and anisotropic charge transport due to symmetry-breaking-induced intrinsic strains. Such band splitting reconstructs the band edge and can decrease the charge carrier effective mass, leading to excellent charge transport properties. Mechanical deformation can further push the orbital energies apart from each other in a more controllable manner, surpassing the impact from intrinsic strains. Both anisotropic charge transport properties andZT values are sensitive to the direction and magnitude of strain, showing a wide range of variation from 20% to 400% (with a ZT value of up to 1.85) compared with unstrained cases. The power generation efficiency of the thermoelectric device can reach as high as approximately 12% using mixed halide perovskites under tailored mechanical deformation when the heat-source is at 500 K and the cold side is maintained at 300 K, surpassing the performance of many existing bulk thermoelectric materials.

关键词： inorganic metal halide perovskites     mechanical deformation     thermoelectrics     first-principle calculations     Boltzmann transport theory    

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Research on the dynamic mechanical characteristics and turning tool life under the conditions of excessively

Genghuang HE, Xianli LIU, Fugang YAN

《机械工程前沿（英文）》 2012年 第7卷 第3期   页码 329-334 doi: 10.1007/s11465-012-0303-x

摘要：

The dynamic mechanical characteristics of excessively heavy-duty cutting were analyzed based on the cutting experiments with 2.25Cr-1Mo-0.25V steel used in hydrogenated cylindrical shells. By investigating the influence of dynamic mechanical characteristics on the tools’ failure in limited heavy-duty cutting processes, the model of dynamic shearing force in the cutting area was established. However, the experimental results showed that the dynamic shear flow stress in the cutting area greatly influenced the tools’ fatigue. The heavy-duty cutting tool was damaged in the form of a shearing fracture. Through a comprehensive analysis of the theory, the critical condition of the tools’ fracture under extreme loading was established.

关键词： extreme loading cutting     shear flow stress     dynamic cutting force     fatigue fracture    

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A time−space porosity computational model for concrete under sulfate attack

《结构与土木工程前沿（英文）》 doi: 10.1007/s11709-023-0985-7

摘要： The deterioration of the microscopic pore structure of concrete under external sulfate attack (ESA) is a primary cause of degradation. Nevertheless, little effort has been invested in exploring the temporal and spatial development of the porosity of concrete under ESA. This study proposes a mechanical–chemical model to simulate the spatiotemporal distribution of the porosity. A relationship between the corrosion damage and amount of ettringite is proposed based on the theory of volume expansion. In addition, the expansion strain at the macro-scale is obtained using a stress analysis model of composite concentric sphere elements and the micromechanical mean-field approach. Finally, considering the influence of corrosion damage and cement hydration on the diffusion of sulfate ions, the expansion deformation and porosity space−time distribution are obtained using the finite difference method. The results demonstrate that the expansion strains calculated using the suggested model agree well with previously reported experimental results. Moreover, the tricalcium aluminate concentration, initial elastic modulus of cement paste, corrosion damage, and continuous hydration of cement significantly affect concrete under ESA. The proposed model can forecast and assess the porosity of concrete covers and provide a credible approach for determining the residual life of concrete structures under ESA.

关键词： expansion deformation     porosity     internal expansion stress     external sulfate attack     mechanical–chemical coupling model    

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Effect of mineral additives and permeability reducing admixtures having different action mechanisms on mechanicaland durability performance of cementitious systems

《结构与土木工程前沿（英文）》 2021年 第15卷 第5期   页码 1277-1291 doi: 10.1007/s11709-021-1752-2

摘要： In this paper, the effect of usage of the permeability reducing admixture (PRA) having different action mechanisms on hardened state properties of cementitious systems containing mineral additives is examined. For this aim, three commercial PRAs were used during investigation. The effective parameters in the first and third PRAs were air-entraining and high-rate air-entraining, respectively. The second one contained the insoluble calcium carbonate residue and had a small amount of the air-entraining property. Mortar mixes with binary and ternary cementitious systems were prepared by partially replacing cement with fly ash and metakaolin. The hardened state properties of mortar mixtures such as compressive strength, ultrasonic pulse velocity, water absorption, drying shrinkage and freeze–thaw resistance were investigated. The ternary cement-based mixture having both fly ash and metakaolin was selected as the most successful mineral-additive bearing mix in regard to hardened state properties. In this sense, PRA-B, with both insoluble residues and a small amount of air-entraining properties, showed the best performance among the mixtures containing PRA. The combined use of mineral additive and PRA had a more positive effect on the properties of the mixes.

关键词： cementitious system     mineral additive     permeability reducing admixture     mechanical properties     durability performance    

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影响微电子机械系统成品率和可靠性和粘合力和磨擦力

王渭源

《中国工程科学》 2000年 第2卷 第3期   页码 36-41

摘要：

文章评述了影响微电子机械系统（MEMS)成品率和可靠性的粘合力和摩擦力问题。在用氢氟酸(HF)腐蚀牺牲层、释放多晶Si微结构、干燥时，由于Si片表面薄层水的表面张力使两片亲水、间隙在微米量级的a片粘合起来，称为“释放有关粘合”。粘合也发生在封装后器件中，当输入信号过冲时，由于Si片表面的化学状态将Si片粘合起来，称为“使用中粘合”。解决粘合的最好办法是：在MEMS微结构的表面涂以抗粘合薄膜，将成品器件在干燥气氛下封装。介绍了抗粘合薄膜的制备工艺和目前存在的问题。相比之下，具有高速运动的MEMS,其摩擦力问题更为复杂。应用抗粘合薄膜，解决了粘合，也降低了摩擦力，但摩擦依然存在。摩擦带来磨损，降低器件可靠性和寿命。寻找既抗粘合、又耐磨的薄膜，是解决高速运动MEMS可靠性和寿命的一个关键。

关键词： 微电子机械系统     粘合力     摩擦力     抗粘合薄膜     耐磨损薄膜    

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Optimal locations of monitoring stations in water distribution systems under multiple demand patterns

Shuming LIU, Wenjun LIU, Jinduan CHEN, Qi WANG

《环境科学与工程前沿（英文）》 2012年 第6卷 第2期   页码 204-212 doi: 10.1007/s11783-011-0364-9

摘要： A flaw of demand coverage method in solving optimal monitoring stations problem under multiple demand patterns was identified in this paper. In the demand coverage method, the demand coverage of each set of monitoring stations is calculated by accumulating their demand coverage under each demand pattern, and the impact of temporal distribution between different time periods or demand patterns is ignored. This could lead to miscalculation of the optimal locations of the monitoring stations. To overcome this flaw, this paper presents a Demand Coverage Index (DCI) based method. The optimization considers extended period unsteady hydraulics due to the change of nodal demands with time. The method is cast in a genetic algorithm framework for integration with Environmental Protection Agency Net (EPANET) and is demonstrated through example applications. Results show that the set of optimal locations of monitoring stations obtained using the DCI method can represent the water quality of water distribution systems under multiple demand patterns better than the one obtained using previous methods.

关键词： demand coverage     monitoring     optimization     water distribution network     water quality    

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标题 作者 时间 类型 操作

Analysis of suitable geometrical parameters for designing a tendon-driven under-actuated mechanical finger

Francesco PENTA,Cesare ROSSI,Sergio SAVINO

期刊论文

Push recovery for the standing under-actuated bipedal robot using the hip strategy

Chao LI,Rong XIONG,Qiu-guo ZHU,Jun WU,Ya-liang WANG,Yi-ming HUANG

期刊论文

Development of a redundant anthropomorphic hydraulically actuated manipulator with a roll–pitch–yaw spherical

期刊论文

Multiscale mechanical modeling of hydrated cement paste under tensile load using the combined DEM-MD

Yue HOU, Linbing WANG

期刊论文

Micro-spectrophotometer based on micro electro-mechanical systems technology

ZHOU Lianqun, LI Zhenggang, WU Yihui, ZHANG Ping, XUAN Ming, JIA Hongguang

期刊论文

Effect of land-use management systems on coupled physical and mechanical, chemical and biological soil

Rainer HORN, Winfried E. H. BLUM

期刊论文

Research on the influence of contact surface constraint on mechanical properties of rock-concrete compositespecimens under compressive loads

Baoyun ZHAO, Yang LIU, Dongyan LIU, Wei HUANG, Xiaoping WANG, Guibao YU, Shu LIU

期刊论文

Preload characteristics identification of the piezoelectric-actuated 1-DOF compliant nanopositioning

Ruizhou WANG, Xianmin ZHANG

期刊论文

Hydrologic experiments and modeling of two laboratory bioretention systems under different boundary conditions

Ruifen Liu, Elizabeth Fassman-Beck

期刊论文

High performance solid-state thermoelectric energy conversion via inorganic metal halide perovskites undertailored mechanical deformation

Lifu YAN, Lingling ZHAO, Guiting YANG, Shichao LIU, Yang LIU, Shangchao LIN

期刊论文

Research on the dynamic mechanical characteristics and turning tool life under the conditions of excessively

Genghuang HE, Xianli LIU, Fugang YAN

期刊论文

A time−space porosity computational model for concrete under sulfate attack

期刊论文

Effect of mineral additives and permeability reducing admixtures having different action mechanisms on mechanicaland durability performance of cementitious systems

期刊论文

影响微电子机械系统成品率和可靠性和粘合力和磨擦力

王渭源

期刊论文

Optimal locations of monitoring stations in water distribution systems under multiple demand patterns

Shuming LIU, Wenjun LIU, Jinduan CHEN, Qi WANG

期刊论文