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排序方式: 共有44条查询结果,搜索用时 15 毫秒
1.
机器人操作器有限时间跟踪中继切换控制   总被引:1,自引:1,他引:0       下载免费PDF全文
A global relay switching control scheme with finite time convergence (FTC) is proposed for multi-joint rigid robotic manipulator systems with uncertain dynamics. For a general finite time controller, the control signals may tend to infinity in finite time when the initial states of the system are in some specified area, causing the singularity problem of the closed-loop system and finite escape.The design scheme for finite time tracking control uses a relay switching control method so that the boundedness of the control signal is guaranteed and the singularity phenomenon is avoided. The validity of our scheme is demonstrated by simulation results.  相似文献   
2.
提出了一种多变量模型不确定系统的自适应二阶终端滑模分解控制方法.通过状态变换和去耦合处理,将系统转换为块能控标准型,变换后的系统由输入输出子系统和零动态子系统组成.通过设计状态反馈,使得零动态子系统成为满足性能要求的稳定系统.提出了特殊的二阶自适应终端滑模超曲面和相应的控制策略,使输入输出子系统状态渐近收敛至平衡点,随后零动态子系统渐近收敛至平衡点.该控制方法对于维数较高系统的控制具有较大的意义,可简化设计,实现鲁棒分解控制.同时,由于采用了二阶滑模的思想,有效地消除了系统的高频抖振.仿真结果表明了该方法的有效性.  相似文献   
3.
优先级有限时的单处理器静态优先级调度   总被引:1,自引:1,他引:0       下载免费PDF全文
静态优先级调度在实际应用中经常受到系统支持的优先级个数的影响,当任务个数多于系统优先级个数时,需要将几个任务优先级映射成一个系统优先级.这可能引起优先级映射问题,使映射前可调度的系统(任务集合)在映射后变得不可调度.解决这一问题需要减少时间复杂度的映射算法和判定映射后任务可调度性的充分必要条件主要存在3种映射算法:(1)按照任务优先级递减顺序进行映射的DPA(decreasing priority assignment)算法;(2)按照优先级递增顺序进行映射的IPA(Increasing priority assignment)算法;(3)阈值段间映射法(thresh01d segment mapping,简称TSM).描述了3种算法的实现和判定条件,论述并证明了算法特性,分析并通过仿真实验比较了算法的性能,最后总结了3种算法各自的适用场合.比较结果和结论对实时嵌入式系统的设计和实现具有一定的参考价值.  相似文献   
4.
提出了一种新的、基于光散射原理的全散射测量法,并相应地发展了TSM微粒测量仪,可用于亚微米或更小颗粒的测量。理论分析和实验研究指出,其测量下限可达0.05μm或更小一些,而上限约为10~20μm。  相似文献   
5.
Scraped surface heat exchangers (SSHEs) are widely used for crystallization applications in several food processes (i.e. crystallization of margarine, tempering of chocolate, freezing of ice cream and sorbet). The final quality of these food products is highly related to crystal size distribution and apparent viscosity, both of which are determined by the operating conditions of the process. During the freezing of sorbet, the increase in the ice volume fraction leads to an increase in the apparent viscosity of the product. This effect modifies the fluid flow behavior, the residence time distribution (RTD) and the temperature profile inside the equipment. This work aimed at studying the influence of the operating conditions on the RTD and the axial temperature profile of the product in a SSHE, so as to characterize the product flow behavior. RTD experiments were carried out in a continuous laboratory pilot-scale SSHE by means of a colorimetric method. Experiments showed that high product flow rates led to a narrowing of the RTD and thus to less axial dispersion, due to the enhancement of the radial mixing with the decrease in the apparent viscosity of the product. Spreading of the RTD was obtained for lower refrigerant fluid temperatures, due to a higher radial temperature gradient between the wall and the center of the exchanger, leading to a higher gradient of the apparent viscosity. This effect increased the difference in axial flow velocities and thus the axial dispersion. These results can be useful for the optimization and modelling of crystallization processes in SSHEs.  相似文献   
6.
The implementation of batch processing has increased due to its intrinsic flexibility and adaptability. These are essential characteristics when it comes to producing high-value added materials such as agrochemicals, pharmaceuticals, specialty chemicals…the demand for which has grown in recent decades.Although industrial processes are highly diverse, a common feature to all is that they utilize fossil fuels as the energy source. The reliance on fossil fuels as a primary source of energy generates a negative impact on the environment. The implantation of renewable energies and efficient usage of energy has thus become crucial. Improving energy use could be achieved through advancements in plant machinery and the use of methodologies such as ‘process integration’.Process integration can be described as system oriented methods that could be used during the design and retrofit of industrial processes in order to obtain an optimal utilization of resources. The methods have traditionally focused on an efficient energy use, although recently process integration techniques cover other areas such as efficient use of raw materials, emission reduction and process operations. Energy integration tries to reach the optimization of heat, power, fuel and utilities.The consideration of energy integration complicates the process design and the generation of batch process design alternatives, so what is now required is the proposal and development of different approaches and methods oriented towards recovering energy in this kind of industrial process. Improving energy end-use efficiency will make it possible to reduce dependence on energy imports and bring about innovation and competitiveness.The aim of this work is report the main contributions that have been carried out in order to attain energy integration in batch processes, as well as different examples of applications that have shown the possibilities offered by the developed tools.  相似文献   
7.
叶 雷  吴根忠  陈 强 《机电工程》2014,(6):764-768,813
针对传统永磁同步电机调速系统面对变负载和大范围调速时,P、I参数需要频繁调整且速度跟踪不理想的问题,提出了一种基于误差反馈学习结构的永磁同步电机有限时间速度控制方法。在对永磁同步电机运动方程分析的基础上,使用非线性PI和径向基神经网络建立了速度环控制器模型。前者保证控制系统收敛和稳定,其输出作为神经网络的误差学习参数;后者基于终端滑模理论设计参数调整律,加快神经网络的参数收敛速度,使得神经网络的输出逐渐取代非线性PI成为控制系统的主要控制器。利用李雅普诺夫稳定判据分析了控制器的收敛性,并在永磁同步电机调速系统上进行了试验。研究结果表明,基于误差反馈学习结构的有限时间控制策略能够减小系统静态误差和抖振,具有一定的抗干扰能力。  相似文献   
8.
本文介绍了基于NFC手机和JAVA SWP卡片如何实现门禁权限线上授权的方法,以解决目前现有的门禁系统中门禁权限管理存在不完善、授权方式不灵活等问题。用户通过手机客户端即可完成门禁权限申请,管理员通过线上系统进行门禁权限的审批,不仅减少线下授权的场所、设备、人员投入,也免去用户携带门禁卡等不便。  相似文献   
9.
随着基于硬件载体的移动支付技术的发展,如何使用户方便、快捷、安全的获取支付应用,已经成为移动支付业务规模化发展的前提条件,因此也受到国内外产业界的关注。可信服务管理(TSM)系统能够通过空中的方式向用户下载支付应用,解决了这一难题,也成为各移动支付业务主导方争相抢占的制高点。文章从TSM在移动支付生态环境中的地位、作用、服务内容、运营模式等四个方面给出了TSM的本质,并基于国外TSM试点应用的情况给出了我国TSM生态环境发展建议。  相似文献   
10.
利用TSM盆地模拟软件,对准噶尔盆地东部石炭系烃源岩的埋藏史、热演化史和生烃史进行分析。结果表明,研究区的沉降中心从侏罗纪到新生代存在由南向北迁移,而后又南移的跷跷板过程。南部的吉木萨尔凹陷内巴塔玛依内山组烃源岩有2个关键的生烃期:侏罗纪末,该烃源岩的镜质体反射率(Ro)分布在0.6%~1.3%之间,新生代中晚期之后,Ro分布在1%~2%之间;北部五彩湾凹陷内滴水泉组烃源岩的关键生烃期为白垩纪末期,Ro大部分在0.7%~1.5%之间,处于生烃高峰期;北部石钱滩凹陷石钱滩组烃源岩白垩纪末则刚进入生烃门限,演化程度低。另外,生烃强度从层位上看,滴水泉组和巴山组相对较大,可达200 mg/g,而石钱滩组较小,最高只有40 mg/g。  相似文献   
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