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1.
基于Project 2003的关键链启发式算法   总被引:2,自引:0,他引:2  
介绍了关键链项目管理的基本方法;针对资源受限项目调度问题,提出了资源冲突时的资源分配原则;以项目工期最小化为目标,以Proiect 2003为辅助工具,提出了一个确定关键链的启发式算法,即在找出关键路径的基础上,从后往前遍历,对发生资源冲突的活动,依资源分配原则修改紧前关系,然后再确定关键链,进而得到了基于关键链项目管理方法的项目调度算法.对算法进行了验证,结果表明算法是有效的.  相似文献   

2.
 基于关键链项目管理(critical chain project management,CCPM),利用一种混合智能优化算法求解多资源约束项目调度问题,解决传统调度优化算法的不足,提高这类问题的求解质量.首先利用一类启发式算法识别项目关键链,并设置缓冲区尺寸,以项目总工期和在制品库存为优化目标建立数学模型,设计一种混合智能优化算法求解,并对项目问题库中的j30hrs.sm问题和某生产型项目进行实验分析,得到优化的结果.实验表明,采用混合智能算法求解这类问题能得到明显优于一般调度优化算法的结果.  相似文献   

3.
针对关键链识别这一关键链调度理论的基本问题,建立了以活动重心为优先规则的两阶段关键链识别启发式求解方法。并运用数理统计学假设检验方法,以Patterson110问题集为样本,将新构建的算法与三种基于较好优先规则的启发式算法进行了比较,统计数据说明论文构建的迭代重心法有一定的先进性,同时极大地简化了关键链的识别过程。  相似文献   

4.
设计人员和技术资源的特点使得产品设计项目优化调度建模及求解的复杂性大大增加。首先对产品设计项目中的三大主要要素的属性进行了深入地分析,并提出了任务-人员-资源匹配度的评价指标和计算方法;其次,借助多模式资源受限问题的思想,将设计人员和技术资源分别考虑,并将设计人员、技术资源和设计任务三者的匹配度以及技术资源强度引入到调度模型中,建立了针对产品设计项目的多模式资源受限调度数学模型;最后,设计了一种双层单亲遗传算法,实现了对模型的求解,得到了工期最短目标下最优的任务、设计人员、技术资源调度方案。案例分析结果表明,基于人员-任务-资源匹配度的多模式优化调度模型充分体现了设计项目的特点,有利于人力资源和技术资源的优化配置。  相似文献   

5.
针对机器故障扰动,研究了炼钢连铸重调度问题及其求解算法.通过将机器故障映射为资源约束,建立了基于动态约束满足的炼钢连铸重调度模型,模型以最大化连浇量与调度方案相似度为目标.针对问题的模型及其特点,采用约束满足和邻域搜索相结合的混合算法对其进行了求解.仿真实验表明本文提出的模型和算法是有效的.  相似文献   

6.
谢阳  叶春明  陈君兰  周蓉 《工业工程》2012,15(3):57-61,91
鉴于基本粒子群算法易陷入局部最优,提出一种将混沌算法嵌入基本粒子群的混沌粒子群算法,并将其用于求解典型的资源受限项目调度问题。采用基于优先值的粒子编码方式和串行调度方案,分别用基本粒子群算法和混沌粒子群算法对实例求解。并且比较了2种算法求解多资源受限项目调度问题的性能。结果表明:混沌粒子群算法在距最优值的平均偏差和达到最优值的次数百分比等性能上要优于基本的粒子群算法,并且混沌粒子群具有更好的收敛性。但是,混沌粒子群算法在计算达到最优工期的平均时间上略比基本粒子群算法逊色。  相似文献   

7.
传统的资源受限多项目调度集中式决策方法已无法满足信息不对称环境下的多项目管理需求,分布式资源受限多项目调度问题研究的是多个自主决策者分别进行全局资源的协调分配决策与局部项目的调度优化决策。鉴于较强的实际应用背景,这类问题逐渐成为项目调度领域新的研究热点。首先,在系统介绍分布式资源受限多项目调度问题特点与模型构建的基础上,分类梳理并评述了问题求解的代表性方法;其次,总结了分布式多项目调度的相关扩展问题以及在不同领域的典型应用;最后,讨论了目前研究中存在的主要问题与未来可能的拓展研究方向。  相似文献   

8.
在分析国内外相关研究现状的基础上,结合资源受限多项目调度问题的特点,针对多项目中各个工序资源参数的不确定性,通过对工程项目工序资源需求量的模糊表示,建立了模糊资源受限多项目调度模型,并运用基于优先规则的启发式算法对所建立的模型进行调度计算,最后通过算例验证模型的有效性和可行性,以实现多项目资源的优化配置。  相似文献   

9.
针对多资源约束的车间调度问题,将启发式算法和自适应GA优化方法结合起来,提出了混合自适应GA方法,建立了多资源约束的车间优化调度模型.根据启发式调度算法中优先规则对调度目标的影响,设计了新的编码规则.采用正弦函数作为自适应因子,使得交叉概率和变异概率随群体的适应度自动改变,提高了运算的效率,克服了启发式算法和普通GA的缺陷.通过实例仿真并与其他算法比较结果表明,混合自适应GA算法可以很好的解决作业车间在机床、刀具等多种生产资源约束下的优化调度,并在评价指标上较其他算法更优.  相似文献   

10.
关键链项目管理中关键链和非关键链的识别   总被引:2,自引:0,他引:2  
运用动态规划的思想设计了一个启发式算法来识别关键链和非关键链.采用此算法对标准问题库PSPLIB中的问题J301_1.SM进行实例求解,识别出来的两条关键链的长度比文献[11,14]中算法求得的长度缩短了6个单位时间.  相似文献   

11.
In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.  相似文献   

12.
13.
A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.  相似文献   

14.
A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.  相似文献   

15.
On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……  相似文献   

16.
Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……  相似文献   

17.
We associate a variety of innovations with the term "Industry 4.0". The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...  相似文献   

18.
In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M2(B,C), (W,Mo)2(B,C), M3(B,C), M23(B,C)6 type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm2. The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K1 mill housing of bar mill.  相似文献   

19.
The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...  相似文献   

20.
Several researches have been reported about the characteristic of β-Ga2O3 nanowires which was synthesized on nickel oxide particle. But indeed, recent researches about synthesis of β-Ga2O3 nanowires on oxide-assisted transition metal are limited to nickel or cobalt oxide catalyst. In this work, Gallium oxide (β-Ga2O3 ) nanowires were synthesized by a simple thermal evaporation method from gallium powder in the range of 700 - 1000℃ using the iron, nickel, copper, cobalt and zinc oxide as a catalyst, respectively. The β-Ga2O3 nanowires with single crystalline without defects were successfully synthesized at the reaction temperature of 850, 900 and 950℃ in all the catalysts. But optimum experimental condition in synthesis of nanowires varied with the kind of catalyst. As increasing synthesis temperature,the morphology of gallium oxide nanowires changed from nanowires to nanorods, and its diameter increased. From these results, we could be proposed that the growth mechanism of β-Ga2O3 nanowires was changed with synthesis temperature of nanowires. Microstructure and morphology of Synthesized nanowire was characterized by HR-TEM, FE-SEM, EDX and XRD.  相似文献   

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