全文获取类型
收费全文 | 1237篇 |
免费 | 26篇 |
国内免费 | 31篇 |
学科分类
工业技术 | 1294篇 |
出版年
2023年 | 9篇 |
2022年 | 11篇 |
2021年 | 14篇 |
2020年 | 7篇 |
2019年 | 22篇 |
2018年 | 13篇 |
2017年 | 40篇 |
2016年 | 42篇 |
2015年 | 42篇 |
2014年 | 67篇 |
2013年 | 61篇 |
2012年 | 46篇 |
2011年 | 95篇 |
2010年 | 36篇 |
2009年 | 70篇 |
2008年 | 63篇 |
2007年 | 74篇 |
2006年 | 78篇 |
2005年 | 73篇 |
2004年 | 61篇 |
2003年 | 53篇 |
2002年 | 46篇 |
2001年 | 24篇 |
2000年 | 21篇 |
1999年 | 27篇 |
1998年 | 33篇 |
1997年 | 27篇 |
1996年 | 14篇 |
1995年 | 12篇 |
1994年 | 14篇 |
1993年 | 14篇 |
1992年 | 12篇 |
1991年 | 13篇 |
1990年 | 6篇 |
1989年 | 12篇 |
1988年 | 15篇 |
1987年 | 10篇 |
1986年 | 5篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1978年 | 2篇 |
排序方式: 共有1294条查询结果,搜索用时 593 毫秒
11.
一种基于时间戳认证的零水印方案设计 总被引:1,自引:0,他引:1
零水印方法是一种新的数字水印方法。本文介绍了零水印的概念及零水印技术的关键问题,提出了一种基于时间戳认证的零水印方案。该方案很好地解决了非零水印的不可见性与鲁棒性之间的矛盾,具有可行性和通用性。 相似文献
12.
数控机床交流伺服系统的复合控制研究 总被引:1,自引:0,他引:1
针对常规P-P与PPI控制存在的问题,提出了在数控机床交流伺服系统中,采用带速度和加速度作为前馈控制,模糊自校正PID控制作为位置反馈控制的复合控制器,实验证明可以显著提高控制系统的控制精度,大大降低跟踪误差,具有较强的鲁棒性。 相似文献
13.
In this paper, we consider least-squares (LS) problems where the regression data is affected by parametric stochastic uncertainty. In this setting, we study the problem of minimizing the expected value with respect to the uncertainty of the LS residual. For general nonlinear dependence of the data on the uncertain parameters, determining an exact solution to this problem is known to be computationally prohibitive. Here, we follow a probabilistic approach, and determine a probable near optimal solution by minimizing the empirical mean of the residual. Finite sample convergence of the proposed method is assessed using statistical learning methods. In particular, we prove that if one constructs the empirical approximation of the mean using a finite number N of samples, then the minimizer of this empirical approximation is, with high probability, an ε-suboptimal solution for the original problem. Moreover, this approximate solution can be efficiently determined numerically by a standard recursive algorithm. Comparisons with gradient algorithms for stochastic optimization are also discussed in the paper and several numerical examples illustrate the proposed methodology. 相似文献
14.
15.
航空发动机传感器故障鲁棒检测方法 总被引:4,自引:0,他引:4
研究发动机传感器故障准确检测问题,现代航空发动机数字电子控制系统对传感器的可靠性要求日益提高。针对航空发动机结构复杂,又工作在高温和高压下,常规采用的传感器故障检测方法的准确性易受到建模误差与外界扰动的影响,造成漏报或误报。为了提高检测精度,提出建立航空发动机数控系统传感器未知输入故障模型,采用特征结构配置的方法,通过配置闭环系统左特征向量实现故障检测残差对不确定性因素的干扰解耦,降低扰动对故障诊断结果的影响。用某型涡扇发动机数控系统传感器故障数字仿真试验表明,所设计的方法对范数有界的不确定量可以实现干扰解耦,抑制干扰对故障检测的影响,改善检测算法的鲁棒性,提高检测结果的准确性,同时满足在线运算的实时性要求。提高了航空发动机的可靠性,保证了安全飞行。 相似文献
16.
本文给出一种简单非线性PID控制器的设计方法。该控制器设计简单.有较好的适应性、鲁棒性和抗干扰性,通过其在电液伺服系统中的应用表明该方法的有效性和可行性,该控制方案能用于机器人等复杂的控制系统中,有较好的应用前景。 相似文献
17.
This paper addresses the problem of designing controllers that are robust to a great uncertainty in a time constant of the plant. Plants must be represented by minimum phase rational transfer functions of an arbitrary order. The design specifications are: (1) a phase margin for the nominal plant, (2) a gain crossover frequency for the nominal plant, (3) zero steady state error to step commands, and (4) a constant phase margin for all the possible values of the time constant (T): 0<T<∞. We propose a theorem that defines the structure of the set of controllers that fulfil these specifications and show that it is necessary for these robust controllers to include a fractional-order PI term. Examples are developed for both stable and unstable plants, and the results are compared with a standard PI controller and a robust controller designed using the QFT methodology. 相似文献
18.
《Automatica》2014,50(11):2737-2764
Adaptive control is a control methodology capable of dealing with uncertain systems to ensure desired control performance. This paper provides an overview of some fundamental theoretical aspects and technical issues of multivariable adaptive control, and a thorough presentation of various adaptive control schemes for multi-input–multi-output systems, literature reviews on adaptive control foundations and multivariable adaptive control methods, and related technical problems. It covers some basic concepts and issues such as certainty equivalence, stability, tracking, robustness, and parameter convergence. It discusses some of the most important topics of adaptive control: plant uncertainty parametrization, stable controller adaptation, and design conditions for different adaptive control schemes. The paper also presents a detailed study of well-developed multivariable model reference adaptive control theory and design techniques. It provides an introduction to multivariable adaptive pole placement and adaptive nonlinear control, and it concludes by identifying some open research problems. 相似文献
19.
20.
In real scheduling problems, some disruptions and unexpected events may occur. These disruptions cause the initial schedule to quickly become infeasible and non-optimal. In this situation, an appropriate rescheduling method should be used. In this paper, a new approach has been proposed to achieve stable and robust schedule despite uncertain processing times and unexpected arrivals of new jobs. This approach is a proactive–reactive method which uses a two-step procedure. In the first step an initial robust solution is produced proactively against uncertain processing times using robust optimization approach. This initial robust solution is more insensitive against the fluctuations of processing times in future. In the next step, when an unexpected disruption occurs, an appropriate reactive method is adopted to deal with this unexpected event. In fact, in the second step, the reactive approach determines the best modified sequence after any unexpected disruption based on the classical objective and performance measures. The robustness measure is implemented in the reactive approach to increase the performance of the real schedule after disruption. Computational results indicate that this method produces better solutions in comparison with four classical heuristic approaches according to effectiveness and performance of solutions. 相似文献