首页 | 官方网站   微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   896篇
  国内免费   53篇
  完全免费   338篇
工业技术   1287篇
  2020年   6篇
  2019年   12篇
  2018年   61篇
  2017年   90篇
  2016年   73篇
  2015年   74篇
  2014年   88篇
  2013年   75篇
  2012年   77篇
  2011年   139篇
  2010年   59篇
  2009年   89篇
  2008年   76篇
  2007年   53篇
  2006年   60篇
  2005年   61篇
  2004年   59篇
  2003年   32篇
  2002年   37篇
  2001年   19篇
  2000年   12篇
  1999年   10篇
  1998年   8篇
  1997年   6篇
  1996年   1篇
  1995年   2篇
  1994年   1篇
  1993年   2篇
  1992年   1篇
  1991年   1篇
  1990年   1篇
  1988年   1篇
  1986年   1篇
排序方式: 共有1287条查询结果,搜索用时 46 毫秒
1.
采用预测控制进行纵向塞曼幅值热稳频的研究   总被引:6,自引:0,他引:6  
产生纵向塞曼频率分裂的He—Ne激光器输出左、右旋圆偏振光,其光强差和激光频率呈稳定的调谐曲线。装置利用单片机采集幅值信号,采用预测控制理论进行数字调节,输出PWM(PulseWidth Modulation)信号补偿激光管的温度以实现热稳频控制。为实现对热稳频大滞后、非线性这一复杂系统的高质量控制,提出了预测控制方法,该方法克服了传统PID(Proportional IntegralDifferential)调节中存在的调整工作量大,控制后果不能及时反馈的不足,适用于各种热稳频过程。数字仿真和实验验证预测控制是稳定的,对模型误差的适应能力强。对10s采样周期,估算得系统频率稳定度达6.7×10~(-9)。  相似文献   
2.
Wei D  Craig IK  Bauer M 《ISA transactions》2007,46(3):429-436
Economic performance is very important to advanced process control projects investigating whether the investment of control technology is worthwhile. In this paper economic performance assessment of a simulated electric arc furnace is conducted. The dependence of controlled variables and the corresponding economic impact are highlighted.  相似文献   
3.
This paper presents a technique of multi-objective optimization for Model Predictive Control (MPC) where the optimization has three levels of the objective function, in order of priority: handling constraints, maximizing economics, and maintaining control. The greatest weights are assigned dynamically to control or constraint variables that are predicted to be out of their limits. The weights assigned for economics have to out-weigh those assigned for control objectives. Control variables (CV) can be controlled at fixed targets or within one- or two-sided ranges around the targets. Manipulated Variables (MV) can have assigned targets too, which may be predefined values or current actual values. This MV functionality is extremely useful when economic objectives are not defined for some or all the MVs. To achieve this complex operation, handle process outputs predicted to go out of limits, and have a guaranteed solution for any condition, the technique makes use of the priority structure, penalties on slack variables, and redefinition of the constraint and control model. An engineering implementation of this approach is shown in the MPC embedded in an industrial control system. The optimization and control of a distillation column, the standard Shell heavy oil fractionator (HOF) problem, is adequately achieved with this MPC.  相似文献   
4.
一类非线性系统的扩展状态空间预测控制   总被引:3,自引:2,他引:1  
针对一类具有输出反馈耦合的离散非线性系统,将过程模型表示为扩展状态空间模型,并利用反馈回路非线性函数在参考轨迹附近的局部线性表示,导出一种具有类似离散PI最优调节器结构并具有未来P步设定值前馈控制的新型预测控制器.因其目标函数中考虑了系统状态的变化,所以控制效果要优于仅考虑预测输出误差的情况.仿真结果表明了它的有效性.  相似文献   
5.
The problem how to identify prediction models of the indoor climate in buildings is discussed. Identification experiments have been carried out in two buildings and different models, such as linear ARX-, ARMAX- and BJ-models as well as non-linear artificial neural network models (ANN-models) of different orders, have been identified based on these experiments. In the models, many different input signals have been used, such as the outdoor and indoor temperature, heating power, wall temperatures, ventilation flow rate, time of day and sun radiation. For both buildings, it is shown that ANN-models give more accurate temperature predictions than linear models. For the first building, it is shown that a non-linear combination of sun radiation and time of day is important when predicting the indoor temperature. For the second building, it is shown that the indoor temperature is non-linearly dependent on the ventilation flow rate.  相似文献   
6.
战术任务规划系统研究   总被引:8,自引:0,他引:8  
周锐  成晓静  陈宗基 《控制与决策》2004,19(4):441-443,447
驾驶员智能决策辅助系统对于提高作战飞机的生存性和完成任务有效性具有重要意义,研究现代军机战术任务规划和管理系统结构、组成及功能,给出了信息融合、态势评估和任务规划各子系统实现方法;基于目标和任务模型,实现了冲突检测与消解,利用模型预测控制的滚动优化和在线校正技术,实现了突发事件情况下战术飞机飞行轨迹的在线规划问题,具有较好的鲁棒性和抗干扰性,研究结果表明了该方法的有效性。  相似文献   
7.
Zhao F  Gupta YP 《ISA transactions》2005,44(2):187-198
Model predictive control (MPC) offers several advantages for control of chemical processes. However, the standard MPC may do a poor job in suppressing the effects of certain disturbances. This shortcoming is mainly due to the assumption that disturbances remain constant over the prediction horizon. In this paper, a simple disturbance predictor (SDP) is developed to provide predictions of the unmodeled deterministic disturbances for a simplified MPC algorithm. The prediction is developed by curve fitting of the past information. A tuning parameter is employed to handle a variety of disturbance dynamics and a procedure is presented to find an optimum value of the tuning parameter online. A comparison is made with the commonly used disturbance prediction on three example problems. The results show that an improved regulatory performance and zero offset can be achieved under both regular and ramp output disturbances by using the proposed disturbance predictor.  相似文献   
8.
In this work the bilinear model predictive control method is applied to control the grade change operations in paper production plants. Because of the high nonlinearity of the grade change processes, control of the grade change operations has been performed manually by experienced engineers in the plants. In some cases the bilinear model can be very effective to represent nonlinear processes. In this study a bilinear model for paper plants is identified first. It is found that the bilinear model tracks the plant without significant discrepancy. Based on the multivariable bilinear plant model the optimal input variables are computed using the one-step ahead prediction method. Even for frequent changes in paper grades the bilinear model predictive control scheme exhibits good control performance.  相似文献   
9.
Gupta YP 《ISA transactions》2004,43(4):499-508
Large benefits are possible by utilizing the solution of the constrained optimization problem involved in model predictive control. For a special case of these problems, the solution can be obtained relatively easily from its relationship with the unconstrained optimum. In this paper, a visualization of the relationship between the constrained and unconstrained optimum is presented. Based upon this relationship, a method for finding the constrained optimum is proposed that is suitable for low-dimensional control systems. A comparison with a linear programming formulation on 2 × 2 and 3 × 3 problems shows that the computational effort can be 10–35 times lower. For such processes, the proposed approach may allow one to avail the benefits of optimization by using the small process control systems already present in many plants.  相似文献   
10.
When designing an accurate automated guidance system for vehicles, a major problem is sliding and pseudo-sliding effects. This is especially the case in agricultural applications, where five-centimetre accuracy with respect to the desired trajectory is required, although the vehicles are moving on slippery ground. It has been established that RTK GPS was a very suitable sensor to achieve automated guidance with such high precision: several control laws have been designed for vehicles equipped with this sensor, and provide the expected guidance accuracy as long as the vehicles do not slide. In previous work, further control developments have been proposed to take sliding into account: guidance accuracy in slippery environments has been shown to be preserved, except transiently at the beginning/end of curves. In this paper, the design of this control law is first recalled and discussed. A Model Predictive Control method is then applied in order to preserve accuracy of guidance even during these curvature transitions. Finally, the overall control scheme is implemented, and improvements with respect to previous guidance laws are demonstrated through full-scale experiments.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司    京ICP备09084417号-23

京公网安备 11010802026262号