首页 | 本学科首页   官方微博 | 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   537篇
  免费   32篇
  国内免费   20篇
电工技术   9篇
综合类   14篇
化学工业   11篇
金属工艺   1篇
机械仪表   16篇
建筑科学   1篇
矿业工程   1篇
武器工业   1篇
无线电   19篇
一般工业技术   163篇
冶金工业   48篇
自动化技术   305篇
  2024年   1篇
  2023年   3篇
  2022年   5篇
  2021年   5篇
  2020年   9篇
  2019年   16篇
  2018年   11篇
  2017年   39篇
  2016年   24篇
  2015年   13篇
  2014年   21篇
  2013年   92篇
  2012年   25篇
  2011年   29篇
  2010年   14篇
  2009年   31篇
  2008年   21篇
  2007年   19篇
  2006年   35篇
  2005年   21篇
  2004年   21篇
  2003年   16篇
  2002年   9篇
  2001年   12篇
  2000年   8篇
  1999年   13篇
  1998年   15篇
  1997年   8篇
  1996年   11篇
  1995年   7篇
  1994年   7篇
  1993年   5篇
  1992年   5篇
  1991年   2篇
  1990年   5篇
  1989年   2篇
  1988年   2篇
  1986年   3篇
  1984年   1篇
  1979年   1篇
  1975年   1篇
  1957年   1篇
排序方式: 共有589条查询结果,搜索用时 31 毫秒
1.
针对传统蚁群算法在无人机3 维航路规划中存在搜索时间长、容易陷入局部最优解的问题,提出一种蚁 群算法的改进策略。将固定翼无人机的性能约束条件作为待扩展节点是否可行的判断条件,减小计算量和算法搜索 时间;对航路点的高度规划采用直接设定策略,将3 维航路规划问题简化为2 维航路规划问题,减小算法的复杂性; 改进全局信息素更新规则和安全启发因子,解决了局部最优解和威胁源规避问题。仿真结果表明:改进蚁群算法与 传统蚁群算法相比,能够有效规划出一条从起点到终点的飞行航路,具有更高的有效性和实用性。  相似文献   
2.
Cloud computing is becoming a profitable technology because of it offers cost-effective IT solutions globally. A well-designed task scheduling algorithm ensures the optimal utilization of clouds resources and reducing execution time dynamically. This research article deals with the task scheduling of inter-dependent subtasks on unrelated parallel computing machines in a cloud computing environment. This article considers two variants of the problem-based on two different objective function values. The first variant considers the minimization of the total completion time objective function while the second variant considers the minimization of the makespan objective function. Heuristic and meta-heuristic (HEART) based algorithms are proposed to solve the task scheduling problems. These algorithms utilize the property of list scheduling algorithm of unrelated parallel machine scheduling problem. A mixed integer linear programming (MILP) formulation has been provided for the two variants of the problem. The optimal solution is obtained by solving MILP formulation using A Mathematical Programming Language (AMPL) software. Extensive numerical experiments have been performed to evaluate the performance of proposed algorithms. The solutions obtained by the proposed algorithms are found to out-perform the existing algorithms. The proposed algorithms can be used by cloud computing service providers (CCSPs) for enhancing their resources utilization to reduce their operating cost.  相似文献   
3.
In this paper, we study the time‐division inter‐satellite link topology generation (TDILTG) problem for the well‐known Chinese BeiDou Global Navigation Satellite System. The TDILTG problem consists in generating a time‐division topology of the inter‐satellite link network for the navigation satellite system to spread systematic data to all satellites via a few source satellites with the purpose of minimizing the time required to spread the data. We propose a mathematical model to formulate the TDILTG problem and study its 2 lower bounds through a thorough analysis of the problem characteristics. We also present a deterministic constructive (DC) algorithm to solve this problem approximately but very quickly, with a time complexity of O(n3), where n is the number of satellites. Extensive experimental studies on a wide range of randomly generated instances show that the proposed DC algorithm is able to obtain the optimal solutions for most tested instances in less than 1 second. Meanwhile, we also validate that the DC algorithm performs well when the problem scale is large. Furthermore, we provide insights of the effects of different instance parameters on the final results.  相似文献   
4.
The warehouse is one of the essential components of logistics and supply chains. The efficiency of the whole chain is affected by the performance of warehouse operations and, more particularly, the storage and retrieval of goods. This paper considers a storage and retrieval problem in a real warehouse with random storage and different types of forklifts, depending on the locations they can access. The problem deals with selecting locations to store/retrieve a predefined set of pallets, assigning an adequately skilled forklift to each operation and determining the order in which each forklift will perform its operations so that the total employed time is minimized. The problem is solved heuristically by decomposing it into three subproblems, each one handling one of the three key decisions of the problem, and taking into account congestion considerations. The paper also studies two modifications of the problem, adding secondary objective functions. Computational results compare the effectiveness of the proposed algorithms for the different problems in a stochastic environment via simulation.  相似文献   
5.
Controlled tabular adjustment (CTA) is a relatively new protection technique for tabular data protection. CTA formulates a mixed integer linear programming problem, which is challenging for tables of moderate size. Even finding a feasible initial solution may be a challenging task for large instances. On the other hand, end users of tabular data protection techniques give priority to fast executions and are thus satisfied in practice with suboptimal solutions. This work has two goals. First, the fix-and-relax (FR) strategy is applied to obtain good feasible initial solutions to large CTA instances. FR is based on partitioning the set of binary variables into clusters to selectively explore a smaller branch-and-cut tree. Secondly, the FR solution is used as a warm start for a block coordinate descent (BCD) heuristic (approach named FR+BCD); BCD was confirmed to be a good option for large CTA instances in an earlier paper by the second and third co-authors (Comput Oper Res 2011;38:1826–35 [23]). We report extensive computational results on a set of real-world and synthetic CTA instances. FR is shown to be competitive compared to CPLEX branch-and-cut in terms of quickly finding either a feasible solution or a good upper bound. FR+BCD improved the quality of FR solutions for approximately 25% and 50% of the synthetic and real-world instances, respectively. FR or FR+BCD provided similar or better solutions in less CPU time than CPLEX for 73% of the difficult real-world instances.  相似文献   
6.
This paper introduces a mathematical model (together with a relaxed version) and solution approaches for the multi-facility glass container production planning (MF-GCPP) problem. The glass container industry covers the production of glass packaging (bottle and jars), where a glass paste is continuously distributed to a set of parallel molding machines that shape the finished products. Each facility has a set of furnaces where the glass paste is produced in order to meet the demand. Furthermore, final product transfers between facilities are allowed to face demand. The objectives include meeting demand, minimizing inventory investment and transportation costs, as well as maximizing the utilization of the production facilities. A novel mixed integer programming formulation is introduced for MF-GCPP and solution approaches applying heuristics and meta-heuristics based on mathematical programming are developed. A multi-population genetic algorithm defines for each individual the partitions of the search space to be optimized by the MIP solver. A variant of the fix-and-optimize improvement heuristic is also introduced. The computational tests are carried on instances generated from real-world data provided by a glass container company. The results show that the proposed methods return competitive results for smaller instances, comparing to an exact solver method. In larger instances, the proposed methods are able to return high quality solutions.  相似文献   
7.
The Mixed Capacity Arc Routing Problem under Time Restrictions with Intermediate Facilities (MCARPTIF) is an extension of the Arc Routing Problem under Capacity and Length Restrictions with Intermediate Facilities (CLARPIF) with application in municipal waste collection. This paper evaluates four constructive heuristics capable of computing feasible solutions for the MCARPTIF with a primary objective to either minimise total cost or to minimise the fleet size. The heuristics were adapted from Path-Scanning and Improved-Merge for the Mixed Capacitated Arc Routing Problem, and compared against two Route-First-Cluster-Second heuristics for the MCARPTIF. The objective was to identify the best performing heuristic for application purposes. In practice, the CARP is often solved for real-time or near real-time decision support. Computational time required by the heuristics was thus also evaluated. Identifying the best heuristic proved difficult due to a lack of realistic MCARPTIF benchmark sets, with the two CLARPIF sets predominantly solved in the literature not resembling actual waste collection instances. Route-First-Cluster-Second heuristics, linked with a new vehicle reduction heuristic performed the worst on the two CLARPIF sets, yet performed the best on new waste collection sets taken from the literature and introduced in this paper. Improved-Merge performed the best on two existing CLARPIF sets and on a realistic set with Intermediate-Facilities incident with the vehicle depot, but struggled on all other sets and in minimising fleet size. Path-Scanning was the most robust heuristic, performing reasonably well on all benchmark sets and both objectives. Results further show that due to the high computational time of one of the Route-First-Cluster-Second heuristics, which was only exposed on realistically sized sets, the slightly worse version is the best alternative when real-time support is required for waste collection applications.  相似文献   
8.
《Ergonomics》2012,55(4):441-475
The operation of machines typically requires attention to instruments that signal the state of the machine. One safeguard against primary instrument malfunction is to provide backup instruments, but this works only if the operators react to malfunction by switching attention to the backups. Little is known about the effect of negative outcomes or feedback on allocation of attention to backup instruments. Four experiments demonstrated that prior practice causes operators of a simulated machine to adapt to instrument malfunction by changing to a suboptimal decision rule rather than by reallocating attention to a different set of instruments. This fallacy appears linked to the operators' failures to notice feedback that they should switch during the simulations and operators' failures to correctly interpret outcome feedback following the simulations. The results raise theoretical questions and warn interface designers not to overrate backup instruments.  相似文献   
9.
为压缩一致性规划的状态空间,并加快一致性规划的求解速度,将常量引入到一致性规划中,定义一致性规划中的常量,形成新的知识表示"多值一致性规划任务",定义多值一致性规划动作模型,提出一致性规划常量合成方法,给出一致性规划常量合成算法.该方法利用常量的特性在所有初始世界状态和所有实例动作中猜测、验证常量.理论分析和实验结果表明该算法能合成正确的一致性规划常量,生成多值一致性规划任务.为说明一致性规划常量的应用效果,把生成的多值一致性规划任务与规划解重用启发式结合求一致性规划解,并与规划系统CFF进行对比实验.实验结果表明求解质量和效率较高.  相似文献   
10.
Dispatching rules are widely used in industry because schedules obtained from optimization procedures can be difficult to implement in the face of executional uncertainties. Barua et al. (Barua, A., Narasimhan, R., Upasani, A. and Uzsoy, R., Implementing global factory schedules in the face of stochastic disruptions. Int. J. Prod. Res., 2005, 43(4), 793–818) implement global schedules obtained from an optimization-based heuristic using a dispatching rule, and outperform myopic dispatching rules in the face of disruptions. However, the computation of the global schedules is still time-consuming for realistic instances. Upasani et al. (Upasani, A., Uzsoy, R. and Sourirajan, K., A problem reduction approach for scheduling semiconductor wafer fabrication facilities. IEEE Trans. Semicon. Manuf., 2006, 19, 216–225) develop a problem reduction scheme based on load disparity between work centres, and report significant reduction in CPU times with minimal loss of solution quality in deterministic experiments. In this paper we integrate the problem-reduction scheme to obtain global schedules with the dispatching approach of Barua et al. (Barua, A., Narasimhan, R., Upasani, A. and Uzsoy, R., Implementing global factory schedules in the face of stochastic disruptions. Int. J. Prod. Res., 2005, 43(4), 793–818) in a multi-product environment with stochastic machine breakdowns and job arrivals. A simulation model of a scaled-down wafer fabrication facility is used to evaluate the performance of the proposed procedures. Results show that the integrated procedure outperforms the benchmark dispatching rules while significantly reducing computation times.  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