关键词： 液压传动   动力机械系统   节能控制  

摘要： 近年来,随着全国环保意识的不断增强,各行各业在发展的过程中都将节能环保意识贯彻在行业的发展中,能源的利用率以及节能的技术都得到了人们的高度关注,但是和发达的国家相比,我国的节能技术以及能源的利用率都好处于比较落后的水平,在节能方面还具有很大的发展空间。液压传动动力机械是一个耗能非常大的系统,本文针对液压传动动力机械系统的节能控制进行了探讨,旨在实现我国的可持续发展。

关键词： 动力机械设备   检修   管理   建议  

摘要： 动力机械设备具有连续性、危险性、经济性以及环境污染性等特点,这就使得在对动力机械设备的检修进行管理的过程中存在较大难度。究其原因,是对动力机械设备检修管理环节做得不到位,加强动力机械设备检修管理的措施,应重点从负责检修管理人员的责任心和执行力这两个方面着手。

关键词： 大截面电缆   金具   短路电流   电动力   有限元计算  

摘要： 采用暂态短路电流计算方法和有限元法,分析了高压大截面电缆短路电动力的计算过程,推导出高压大截面电缆金具短路电动力的计算公式,同时考虑电缆蛇形敷设因素、导体外层介质缓冲作用及电缆位移偏转量,引入短路电动力工频分量(50 Hz)修正系数K1和两倍工频分量(100 Hz)修正系数K2对作用在电缆金具上的短路电动力进行修正。基于ANSYS建立电缆金具系统三维有限元计算模型,分别研究电缆敷设跨距和相间距对金具应力场的影响,并对双桥子-桃乡220 k V电缆段进行计算。由计算结果可知,在螺杆中点处产生的应力最大,即该位置最易变形或拉裂,对于220 k V电缆工程中"一"字形排列形式,电缆敷设跨距和相间距分别应满足l≤2.7 m,0.28 m≤a≤0.30 m。

关键词： 混合动力车辆   机械自动变速器   换挡过程   转矩控制  

摘要： 基于"虚拟离合器"技术的自动机械变速器换挡过程的关键是动力中断过程中电机的主动同步与执行机构的挂挡控制。通过对自动机械变速器中同步器的接合机理分析,提出一种基于电机转矩控制的变速器输入端主动同步方法,即通过电机的转矩输出取代传统同步器依靠换挡力产生的同步摩擦力矩来消除进挡过程中同步器主从动部分的转速差。试验验证的结果表明,基于电机转矩控制的自动机械变速器换挡过程控制方法可以降低同步器的磨损,缩短动力中断的时间,提高进挡成功率与可靠性。

关键词： 机械动力设备   检修管理   问题   策略  

摘要： 企业机械动力设备的检修管理关系到设备的检修效率、检修质量、检修成本等,对企业的安全生产和持续发展具有重要作用。鉴于此,文章基于企业机械动力设备检修管理的视角,简单分析了机械动力设备检修管理存在的主要问题,在此基础上,从创新检修管理模式,构建高效检修管理系统等方面探索了机械动力设备检修管理的优化策略,为机械动力设备的检修管理提供一定的借鉴。

关键词： Flexible hybrid electronics   Energy harvesting   ETSOI technology   Layer transfer  

摘要： In this work, we demonstrate mechanically flexible extremely thin silicon on insulator (ETSOI) ring oscillators with a stage delay of similar to 16 ps at a power supply voltage of 0.9 V. Extensive electrical analyses of the flexible ETSOI devices reveal the unchanged properties of the devices during the layer transfer process. Furthermore, we discuss the use of flexible silicon and gallium arsenide photovoltaic energy harvesters for powering flexible ETSOI ring oscillators under different illumination conditions. Our results illustrate innovative pathways for the implementation of optically powered flexible ETSOI technology in future flexible hybrid electronics. (C) 2015 Elsevier Ltd. All rights reserved.

关键词： Magnetofluid   Hydrodynamic lubrication   Mechanical seal   Spiral groove  

摘要： This work presents an experimental study on the lubrication characteristics of the magnetofluid film in a spiral groove mechanical seal to reveal how the magnetic field affects the hydrodynamic effect of magnetofluid. The experiments are carried out based on the non-contact mechanical seal experimental rig and the influences of the magnetic field intensity and the rotational speed on the film thickness, friction torque, characteristic temperature and magnetofluid depletion are investigated experimentally. By numerically analyzing the film pressure distribution, it is revealed that the hydrodynamic pressure increases with the increasing magnetic field intensity. Using an appropriate closing force, it is feasible to control the seal capacity of the seal by regulating the current intensity in the magnetic field generator. (C) 2015 Elsevier Ltd. All rights reserved.

关键词： Dentin caries models   Demineralization kinetics   AFM-nanoindenation   MicroXCT   TEM   SAXS  

摘要： Objectives: We studied artificial dentin lesions in human teeth generated by lactate and acetate buffers (pH 5.0), the two most abundant acids in caries. The objective of this study was to determine differences in mechanical properties, mineral density profiles and ultrastructural variations of two different artificial lesions with the same approximate depth. Methods: 0.05 M (pH 5.0) acetate or lactate buffer was used to create 1) 180 mu m-deep lesions in non-carious human dentin blocks (acetate 130 h;lactate 14days);(2) demineralized, similar to 180 mu m-thick non-carious dentin discs (3 weeks). We performed nanoindentation to determine mechanical properties across the hydrated lesions, and micro X-ray computed tomography (MicroXCT) to determine mineral profiles. Ultrastructure in lesions was analyzed by TEM/selected area electron diffraction (SAED). Demineralized dentin discs were analyzed by small angle X-ray scattering (SAXS). Results: Diffusion-dominated demineralization was shown based on the linearity between lesion depths versus the square root of exposure time in either solution, with faster kinetics in acetate buffer. Nanoindentation revealed lactate induced a significantly sharper transition in reduced elastic modulus across the lesions. MicroXCT showed lactate demineralized lesions had swelling and more disorganized matrix structure, whereas acetate lesions had abrupt X-ray absorption near the margin. At the ultrastructural level, TEM showed lactate was more effective in removing minerals from the collagenous matrix, which was confirmed by SAXS analysis. Conclusions: These findings indicated the different acids yielded lesions with different characteristics that could influence lesion formation resulting in their distinct predominance in different caries activities, and these differences may impact strategies for dentin caries remineralization. (C) 2015 Elsevier Ltd. All rights reserved.

关键词： Mechanoluminescence   Electroluminescence   Color   Dual-channel   Composite  

摘要： Mechanoluminescent (ML) materials, which luminesce in response to mechanical stimuli, are attractive candidates in developing energy-sustainable technology and are widely used in sensors, ubiquitous tight sources, and displays. Metal-doped zinc sulphide (ZnS) is considered a promising ML material because it produces intense and lasting luminescence under repeated mechanical stresses. Previous studies of ZnS luminescence have focused on single-channel emission by electroluminescence (EL) or ML generated by applied electric fields or mechanical stresses, respectively. Here, we report the simultaneous generation of EL and ML from an elastomeric ZnS composite embedded with silver nanowires and demonstrate the independent control of both EL and ML responses. We describe the tuning of the strength and color of the EL/ML emissions from a single ZnS-based structure by applying combinations of electrical and mechanical excitation forces. We also demonstrate a multi-color-patterned EL/ML emitting display using the ZnS-based composite;this application may provide a basis for the development of new optomechanical displays. (C) 2016 Elsevier Ltd. All rights reserved.

关键词： mechanical valve   Heart Valves   Hemodynamics   Hemolysis   patenting  

摘要： Purpose. This study compared the performance of a newly patented synchronized valve (SV) with that of a commercially available (CAV) bileaflet mechanical heart valve. Description. A high-speed camera was used to record the leaflet kinematics of the SV vs the CAV along the flow channel. Transvalvular energy loss, effective orifice area, and hemolysis ratios were obtained using a mock circulatory system at two fixed pulse rates and at various cardiac outputs with a fixed aortic pressure. Evaluation. The rotational radius and inertia of the SV was lower than that of the CAV during valve closure. For heart rates and at cardiac outputs of 7, 5, and 4 L/min, the ratio of total energy loss to effective energy of the SV was significantly less than the CAV, whereas the effective orifice area of the SV was significantly larger than that of CAV. The hemolysis ratio after 4 hours was significantly higher in the CAV than in the SV for both pulse rates. Conclusions. The synchronized leaflet motion mitigated leaflet rebound and regurgitation during valve closure, which could decrease energy loss, increase the effective orifice area, and reduce hemolysis. (C) 2016 by The Society of Thoracic Surgeons