共查询到10条相似文献,搜索用时 171 毫秒
1.
《Measurement》2014
The composite spectrum (CS) data fusion technique has been shown to simplify rotating machines faults diagnosis by earlier studies. Faults diagnosis with the earlier CS relied solely on the amplitudes of several harmonics of the machine speed, owing to the loss of phase information leading to its computation. The proposed improved CS applies the concept of cross power spectrum density for computing a poly-Coherent Composite Spectrum (pCCS) of a machine, which retains amplitude and phase information at all measurement locations. The present study compares the proposed pCCS method with the earlier CS method for faults diagnosis in rotating machines, using experimental data from a rotating rig. Results and observations show that the proposed pCCS offered a much better representation of the machines dynamics when compared to the earlier CS method and hence better fault diagnosis. 相似文献
2.
M.-Y. Yang J.-H. Park 《The International Journal of Advanced Manufacturing Technology》2002,19(9):664-668
This paper deals with the design and implementation of an open architecture CNC system for wire electrical discharge machining
(WEDM) with a consideration of the differences between WEDM and NC cutting machines. Work using open architecture controllers
(OACs) has focused mainly on metal cutting machines. WEDM has many aspects similar to milling machines. However, there are
differences in the machining processes and control strategies. To close the gap between previous general work on OAC and the
WEDM specific needs, an open architecture NC model for WEDM comprised of a synchronisation kernel and an NC functional module
is proposed. The proposed CNC system is applied to an existing commercial WEDM system by a retrofitting method. A precise
NURBS interpolation function is implemented and sample runs are conducted with a NURBS interpolator that is added to the proposed
system. 相似文献
3.
Jesus Rooney Rivera-Guillen Rene de Jesus Romero-Troncoso Roque Alfredo Osornio-Rios Arturo Garcia-Perez Gilberto Herrera-Ruiz 《The International Journal of Advanced Manufacturing Technology》2010,51(5-8):723-737
High speed and high precision on computer numerically controlled (CNC) machines are major issues for most industrial automation processes. Among the most important factors for precise motion control are the control law, the controller implementation, and the profile reference. The effects of the control law and controller implementation on the tracking error in CNC machines have been widely studied, while the issue of profile reference has not received the required attention. To improve the dynamics provided by the conventional profile reference, several techniques have been proposed, focusing on peak jerk limitation. The novelty of this work is to develop a generalized methodology designed for producing dynamically constrained higher degree piecewise polynomial profiles, without limits in maximum polynomial degrees. They lead to define in an arbitrary way the dynamics shape, while the peak dynamics values constrained are maintained in order to improve the tracking error on CNC systems and giving the possibility to design fully dynamic-controlled trajectories. For experimentation purposes, a two-axis proportional–integral–derivative controller and profile reference generator are implemented in a low-cost field programmable gate array. The experimentation demonstrates the efficiency of the proposed methodology, showing the peak jerk and tracking error reduction, compared against recent reports from literature. 相似文献
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Taeho Park Taehyung Lee Chang Ouk Kim 《The International Journal of Advanced Manufacturing Technology》2012,59(1-4):325-333
This paper addresses job scheduling problems with parallel machines. To satisfy customers better in a manufacturing company, meeting due dates has been an important performance metric. Besides the numerous other factors affecting due date satisfaction, the splitting of a job through parallel machines can contribute to the reduction of production lead time, resulting in less job tardiness against their due dates. Thus, this paper presents heuristic algorithms for minimizing total tardiness of jobs to meet their due dates in a manufacturing shop with identically functioning machines. The algorithms take into account job splitting and sequence-dependent major/minor setup times. The performance of the proposed heuristics is compared with that of past three algorithms in the literature. 相似文献
7.
一种基于时间窗的多阶段混合流水车间调度方法 总被引:2,自引:0,他引:2
考虑同时包含单处理机和批处理机的多阶段混合流水车间调度问题,设计一种基于时间窗的蚁群算法,以最小化最大完工时间为优化目标。在解决整体调度问题的过程中,通过蚁群算法实现工序分派、排序、组批三个阶段的协同优化调度;另外在工件组批阶段加入时间窗策略,利用前瞻性算法动态构建组批方案,通过分析批处理机的时空关系设计合理的组批时间窗,以获得较高的机器利用率。试验结果表明,与无时间窗的蚁群算法相比,时间窗策略在确保最小化最大完工时间的同时,提高了批处理机的利用率;与CPLEX相比,基于时间窗的蚁群算法在最大完工时间和计算效率方面均有较大优势。蚁群算法与时间窗的结合兼顾了多个阶段多种机型的生产特点,适用于解决多阶段混合流水车间的调度问题。 相似文献
8.
依据工程机械的构成特点,提出了工程机械生命周期评价的一般模型,基于该模型设计并开发了工程机械生命周期评价软件系统,并以实例说明了系统的应用价值。 相似文献
9.
Ant colony optimization for group technology applications 总被引:1,自引:1,他引:0
Anil Kumar Agrawal Prabhas Bhardwaj Vivek Srivastava 《The International Journal of Advanced Manufacturing Technology》2011,55(5-8):783-795
The problem of grouping of parts into part-families and that of machines into machine-cells has attracted the attention of many researchers particularly for medium variety of parts with medium production volume requirement, which traditionally required their production in batches for achieving economics of production. This kind of grouping, consequently offering benefits of mass production, was aimed to have independent cells processing ideally almost different sets of part-types. For this purpose, a number of approaches are available from various kinds of heuristics to mathematical programming formulations. Evolutionary methods such as neural network, genetic algorithm, and simulated annealing have also been tried and have been found to provide better grouping solutions with much less computational complexity. In the present paper, ant colony optimization approach with number of newer strategies, incorporating more generalised framework of ants’ behaviour, has been applied to the parts and machines grouping problems taken from the literature. The results obtained from their application were found to be encouraging and thus establish the usefulness of the proposed approaches. Average performance of Tabu search with multiple ants was found to be the best and thus the parameter values for this approach were also determined using design of experiments methodology. 相似文献
10.
S. Pugazhendhi S. Thiagarajan C. Rajendran N. Anantharaman 《The International Journal of Advanced Manufacturing Technology》2004,23(11-12):820-830
The flowline-based manufacturing system (FBMS) is a manufacturing environment wherein machines are arranged in the order in which jobs undergo operations, and jobs have an identical and uni-directional flow pattern. However, some or all jobs may not require processing on some machines. Scheduling of jobs in such a FBMS is considered in this paper with the focus on the development of non-permutation schedules. The significance of non-permutation schedules in improving the schedule performance measures, in the context of FBMS’s, is first brought out. A heuristic procedure to derive non-permutation schedules from a given permutation schedule is subsequently proposed. The minimization of total flowtime of jobs is considered as the objective in the first instance, followed by the consideration of the minimization of total weighted flowtime of jobs. An extensive computational experimentation has been performed to evaluate the effectiveness of the proposed heuristic in improving the performance measures. Further, the performance of the proposed heuristic in generating non-permutation schedules has been compared with that of the benchmark dispatching rules namely, the SPT and SWPT rules. 相似文献