全文获取类型
收费全文 | 1246篇 |
免费 | 84篇 |
国内免费 | 58篇 |
专业分类
电工技术 | 154篇 |
综合类 | 49篇 |
化学工业 | 44篇 |
金属工艺 | 43篇 |
机械仪表 | 176篇 |
建筑科学 | 42篇 |
矿业工程 | 13篇 |
能源动力 | 44篇 |
轻工业 | 9篇 |
水利工程 | 10篇 |
石油天然气 | 6篇 |
武器工业 | 15篇 |
无线电 | 73篇 |
一般工业技术 | 198篇 |
冶金工业 | 99篇 |
原子能技术 | 16篇 |
自动化技术 | 397篇 |
出版年
2024年 | 1篇 |
2023年 | 11篇 |
2022年 | 11篇 |
2021年 | 21篇 |
2020年 | 26篇 |
2019年 | 25篇 |
2018年 | 26篇 |
2017年 | 30篇 |
2016年 | 51篇 |
2015年 | 52篇 |
2014年 | 78篇 |
2013年 | 94篇 |
2012年 | 49篇 |
2011年 | 109篇 |
2010年 | 65篇 |
2009年 | 85篇 |
2008年 | 77篇 |
2007年 | 82篇 |
2006年 | 82篇 |
2005年 | 65篇 |
2004年 | 61篇 |
2003年 | 55篇 |
2002年 | 44篇 |
2001年 | 27篇 |
2000年 | 22篇 |
1999年 | 28篇 |
1998年 | 23篇 |
1997年 | 17篇 |
1996年 | 7篇 |
1995年 | 16篇 |
1994年 | 8篇 |
1993年 | 5篇 |
1992年 | 7篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 7篇 |
1986年 | 4篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1962年 | 1篇 |
排序方式: 共有1388条查询结果,搜索用时 78 毫秒
21.
22.
The perpetual energy production of a wind farm could be accomplished (under proper weather conditions) if no failures occurred. But even the best possible design, manufacturing, and maintenance of a system cannot eliminate the failure possibility. In order to understand and minimize the system failures, the most crucial components of the wind turbines, which are prone to failures, should be identified. Moreover, it is essential to determine and classify the criticality of the system failures according to the impact of these failure events on wind turbine safety. The present study is processing the failure data from a wind farm and uses the Fault Tree Analysis as a baseline for applying the Design Structure Matrix technique to reveal the failure and risk interactions between wind turbine subsystems. Based on the analysis performed and by introducing new importance measures, the “readiness to fail” of a subsystem in conjunction with the “failure riskiness” can determine the “failure criticality.” The value of the failure criticality can define the frame within which interventions could be done. The arising interventions could be applied either to the whole system or could be focused in specified pairs of wind turbine subsystems. In conclusion, the method analyzed in the present research can be effectively applied by the wind turbine manufacturers and the wind farm operators as an operation framework, which can lead to a limited (as possible) design‐out maintenance cost, failures' minimization, and safety maximization for the whole wind turbine system. 相似文献
23.
This paper reports a failure mode analysis of a boxer diesel engine crankshaft. Crankshafts are components which experiment severe and complex dynamic loadings due to rotating bending combined with torsion on main journals and alternating bending on crankpins. High level stresses appear on critical areas like web fillets, as well as the effect of centrifugal forces and vibrations. Since the fatigue fracture near the crankpin-web fillet regions is one of the primary failure mechanisms of automotive crankshafts, designers and researchers have done the best for improving its fatigue strength. The present failure has occurred at approximately 2000 manufactured engines, and after about 95,000 km in service. The aim of this work is to investigate the damage root cause and understand the mechanism which led to the catastrophic failure. Recommendations for improving the engine design are also presented. 相似文献
24.
This paper revisits the problem of enlarging the domain of attraction of a linear system with multiple inputs subject to actuator saturation by designing a switching anti-windup compensator. The closed-loop system consisting of the plant, the controller and the anti-windup compensator is first equivalently formulated as a linear system with input deadzone. We then partition the input space into several regions. In one of these regions, all inputs saturate with the time-derivative of the saturated input being zero. In each of the remaining regions, there is a unique input that does not saturate. The time derivative of the deadzone function associated with the unsaturating input is zero. By utilizing these special properties of the inputs on an existing piecewise Lyapunov function of the augmented state vector containing the deadzone function of inputs, we design a separate anti-windup gain for each region of the input space. The switching from one anti-windup gain to another is activated when the input signals leave one region for another, which can be implemented online since only the measurement of the input signals is required. Simulation results indicate that the proposed approach has the ability to obtain a significantly larger estimate of the domain of attraction than the existing approaches. 相似文献
25.
26.
Switching‐based state tracking of model reference adaptive control systems in the presence of intermittent failures of all actuators 下载免费PDF全文
Caiyun Wu Chensong Li Jun Zhao 《International Journal of Adaptive Control and Signal Processing》2014,28(11):1094-1105
This paper investigates the state tracking problem for a class of model reference adaptive control systems with intermittent failures of all actuators. We consider the case that all actuators may suffer failures simultaneously. The concepts of failure frequency and unavailability rate are introduced to describe the failures. Because of the actuator failures, the error system is modeled as a switched system. Then, the notion of global practical stability of switched systems is presented, and sufficient conditions are provided to guarantee the global practical stability of the error system. An example of HiMAT vehicle and the simulation results demonstrate the feasibility and effectiveness of the proposed design method. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
27.
R. F. Escobar-Jimenez D. A. Carbot-Rojas V. M. Alvarado-Martínez A. C. Téllez-Anguiano J. A. Hernandez-Perez 《Chemical Engineering Communications》2017,204(1):86-96
In this work, an experimental fault tolerant control (FTC) implementation is presented. The FTC is based on a multi-input multi-output (MIMO) model predictive control (MPC). The aim of the FTC is to keep on operating a double-pipe counter-current heat exchanger even if the main actuator of the heat exchanger is stuck open. To develop the FTC, an adaptive observer was implemented in order to design a fault detection and isolation (FDI) system. In the FDI system, the cold and hot water flow rate estimations by the adaptive observer are compared to the control signals provided by the MPC. The results of the implementation of the FTC using a MIMO model predictive control were compared to the results obtained in a previous work which was developed using model-following control. 相似文献
28.
Pitting corrosion damage often occurs in aluminum alloy structures and can significantly reduce the service life of structures and cause structural failures. In this research, three-dimensional corrosion pit morphology of 7075-T6 aluminum alloy was observed with the Sensofar PLμ confocal imaging profiler and scanning electron microscope. According to the corrosion pit morphology, we systematically investigated the quantitative correlation between the stress state and geometric features of a corrosion pit idealized as a semi-ellipsoidal pit. It is found that the stress concentration factor (SCF) increases with Rs (the ratio of pit width to length) and Rd (the ratio of pit depth to half-length). The maximum possible SCF is independent of Rd and increases linearly with Rs. The SCF of a rotated pit increases with the orientation angle in a cos2θ relation when Rs < 1.0. The empirical equations are also proposed to correlate the SCF to Rs, Rd and θ. 相似文献
29.
Liangyin Zhang 《International journal of control》2016,89(5):1047-1064
This paper investigates the problem of event-triggered control for semi-global stabilisation of null controllable systems subject to actuator saturation. First, for a continuous-time system, novel event-triggered low-gain control algorithms based on Riccati equations are proposed to achieve semi-global stabilisation. The algebraic Riccati equation with a low-gain parameter is utilised to design both the event-triggering condition and the linear controller; a minimum inter-event time based on the Riccati ordinary differential equation is set a priori to exclude the Zeno behaviour. In addition, the high–low gain techniques are utilised to extend the semi-global results to event-based global stabilisation. Furthermore, for a discrete-time system, novel low-gain and high–low-gain control algorithms are proposed to achieve event-triggered stabilisation. Numerical examples are provided to illustrate the theoretical results. 相似文献
30.
In this paper a new model to predict the wake of vertical axis wind turbines (VAWT) is proposed and analysed. The model is based on the actuator disk and the Double Multiple Stream Tube methods. Specifically, the model, denoted as Multiple Actuator Block, is based on the definition, inside the computational domain, of multiple parallelepipedic blocks distributed along the path of the blades. Volumetric momentum sinks are imposed in these blocks to model the effect of the blades on the flow. To analyse the performance of the model a VAWT with three NACA0022, for which numerical and experimental results are available in the literature, has been considered. Different types of simulations with the Multiple Actuator Block model have been carried out and have been compared with a complete finite volume simulation using the sliding mesh technique. This simulation requires about ten times more CPU time than the simulations using the Multiple Actuator Block model. It has been found that the large scale features of the far wake can be reproduced using the Multiple Actuator Block model applying in the block the forces, obtained from the complete finite volume simulation or obtained from a boundary-layer type code, when the blade is inside the block. 相似文献