The Mixed Disc Packing Problem: Part II. An Interactive Optimization Procedure

In this paper we present an interactive optimization procedure for a mixed disc packing problem. The procedure is based on the bounds on the area left uncovered by the circular disks when packed on the circular plate (developed in Part I) and is implemented on a computer graphics terminal. The proposed procedure is applied to problems involving two and three types of discs and results are presented.     

Highly filled particulate thermoplastic composites: Part I Packing density of irregularly shaped particles

The packing density of irregular shaped particles greatly affects the properties of highly filled particulate composite materials. The effects of particle size distribution parameters on the packing density of fused silica powder and cristobalite flour powder of different size ranges is reported. Various size distributions, according to the log-normal function, were prepared by sieving and characterized by light scattering, using a Malvern 2600 light scattering instrument. The apparent and tap density of the various powders was used to characterize the packing density. The size distribution width was found to have a major effect on the packing density. In addition, the particle size was found to affect the packing density however, its significance depends on the size range and shape of the particles. Mixtures of powders, each having a different size distribution, behave differently. This revised version was published online in November 2006 with corrections to the Cover Date.     

谈食品气调包装中的气体质量问题

介绍了气体在气调包装中的作用,同时强调了气体质量对食品气调包装的重要性,在开展此工作时必须重视气体的质量。     

包装工房炸药装车问题的探讨

文章针对炸药生产线的安全问题,分析了成品炸药装车转运现状,分析计算了炸药不殉爆距离.利用防护土堤与自动隔爆门的防护作用,采用皮带运输机将炸药转运至防护屏障外,实现了包装工序至上车的连续化、自动化作业.     

The Measurement of Real and Virtual Packing Density of Soft Grains

This article analyses the measurements of packing densities realized for grains of different nature and size. The measurements were obtained using several methods. The aim is to propose a method for “soft” grains that suffer abrasion when packed in a cylindrical container and subjected under 10 kPa compression to vibration, which is the conventional approach. Less demanding methods are proposed that involve horizontal, vertical or combined accelerations without additional stress. The packing index does not suffice, however, as in the standard test to characterize these approaches. The results are in most cases governed by the size of the grains and the diameter of the container. Models were then calibrated and validated to calculate, from experimental parameters, the packing index that must be associated to every measure. By convention, soft aggregate materials are those which poorly resist wearing and of which Micro Deval wearing coefficient, in the presence of water, exceeds 40.     

$M$ 矩阵的线性互补问题的误差界

研究了线性互补问题的误差界。首先,利用主对角部分为单位矩阵的 $M$ 矩阵的一个函数,给出该类线性互补问题的误差界理论。之后,通过线性互补问题的模型转化,将误差界理论进行推广,给出系数矩阵为一般 $M$ 矩阵的线性互补问题的误差界。用低阶和高阶的例子对误差界理论进行了验证和比较。数值结果表明,提出的误差界理论是有效的和实用的。     

浅析当前食品包装材料中存在的问题

本文主要分析了近年来食品包装材料中暴露出来的问题,并总结归纳了目前我国食品包装标准相关的卫生标准和产品标准及主要的检测项目,并提出了解决问题的一些浅显思考.     

The stochastic flowshop makespan. Part I. Some general results for the buffered case

This, the first part of a two-part study, considers stochastic flowshops with infinite bufferage. There is a discussion of the modes into which the jobs may fall and expressions are developed for the associated probabilities and makespan-contributions. Various ‘symmetries’ are noted. Exact results are presented for cases up to and including three jobs through three machines when these service times are exponentially distributed and consideration is given to the varying of the distribution parameters. Part II, which follows in the next issue and which should be read in conjunction, deals with the unbuffered flowshop and discusses the well-known ‘bowl effect’     

混合骨料堆积模型研究与新型模型建立

骨料堆积密实度不仅影响混凝土和充填体的强度,还关系到新拌混凝土或充填料浆的和易性与管输性,因此它是混凝土工程和充填矿山研究课题之一。本实验在明确基本概念的基础上,首先探讨了五个堆积率计算模型的特性。然后分析了三个颗粒间相互作用影响堆积率的壁效应及松动效应模型,讨论其差异性及适用范围。针对金川镍矿废石骨料进行堆积密实度实验和计算模型验证,结果表明,不同粗细颗粒混合比下所适用的模型也不同,现有堆积模型难以精确预测实际堆积率。最后提出基于径向基函数(RBF)神经网络黑盒建模思路及实现过程,建立能准确预测骨料堆积率计算的通用模型,并对模型特点进行了讨论。     

Crack formation in mesophase pitch-basedcarbon fibres: Part I Some influential factors for crack formation

The crack observable in the transverse section of mesophase pitch-based graphitized fibres was studied to clarify its development on spinning, stabilization, carbonization and graphitization, and to find the factors influential on the development on spinning. The crack was already observed as an embryo in the as-spun fibre of radial texture, which increased the opening angle according to the extent of shrinkage due to carbonization and graphitization. The spinning temperature, length/diameter, diameter and wall material of the spinning nozzle and the kind of mesophase pitch were found influential in crack development, defining the transverse texture and the extent of longitudinal alignment along the fibre axis. Although the radial texture defined under an optical microscope tends to give a crack, not all of such textures carried the crack, suggesting the necessity of more detailed classification of the texture in terms of alignment, shape and size of domains observed under high resolution scanning electron microscopy (HR-SEM). The factors revealed as being influential on the textures appear to be related to the apparent viscosity, the perfectness of the radial orientation and die-swelling at the outlet of the nozzle to modify the texture defined through the nozzle. The interaction of the mesophase pitch with the nozzle wall and flow properties should be emphasized as factors controlling the texture on spinning. This revised version was published online in November 2006 with corrections to the Cover Date.     

The Segregated Storage Problem: Some Properties and an Effective Heuristic

The segregated storage problem is formulated as an integer programming problem. Some special cases are shown to reduce to ordinary assignment problems. A special property of the integer formulation is used to develop a new heuristic procedure which produces near optimal solutions and which can be used as a tight bound in branch and bound procedures. Computational comparisons with heuristics proposed by other authors indicate this method to be superior in solving large problems.     

填料堆积密度对SMC工艺及性能的影响

根据填料球-球双峰堆砌理论,通过激光粒度分析仪测定了几种不同比例填料复合后的粒径分布,使用连续级分法计算复合后填料的空隙率,得到了可实现密堆砌填料的类型和复合比例;通过测试树脂糊黏度、片状模塑料(SMC)试样的力学性能以及模压产品的表面波纹,研究了密堆砌填料对SMC生产的工艺性、力学性能以及模压产品表面质量的影响。结果表明,使用密堆砌的填料可实现树脂糊在初始黏度相同的情况下多加入填料30份,同时,SMC的冲击性能有明显的提高,且产品的表面质量得到了显著的改善。     

基于混合遗传算法的多箱型三维装箱问题研究

目的 提高电商仓储领域打包环节包装箱的利用率。方法 针对电商仓储领域多箱型多种物品类型的三维装箱问题,建立混合整数规划的数学模型,设计基于启发式经验规则和多种算子组合的装箱过程模块算法。分别从装箱顺序和带有改进型算子这两方面设计多箱型三维装箱问题混合遗传算法,对装箱方案进行优化。结果 经实验证明,在装箱顺序优化环节PSO–HGA算法系列中,PSO–HGA–S1算法最优。在带有改进算子的混合遗传算法中,IPO–HGA–S1算法最优。结论 文中设计的混合遗传算法能很好地提高电商仓储领域打包环节包装箱的利用率。     

单一规格物体二维矩形条带装箱问题解法研究

为了克服用启发式算法及智能搜索法解决单一规格物体二维矩形条带装箱问题耗时过长的缺陷,提出了新的解法和思路.用线性规划法分别在2个维度求最优解,以最好的方案作为近似最优解,可大幅度缩短求解时间,获得满意的近似最优解.     

类模式组合装箱问题模型与精确算法研究

研究基于汽车出场物流实践而提出的类模式组合装箱问题。主要考虑组合装载及运力意向约束,并以最大化商品车装载数量、最大化商品车装载总紧急程度为主要目标。首先建立混合整数规划模型。其次设计基于分枝定界策略的精确算法。最后,通过基于ILOG CPLEX优化工具的数值实验以及案例分析,验证所提出模型和算法的有效性与高效性。     

The Mixed Mode Crack Problem in an Inhomogeneous Orthotropic Medium

The mixed mode crack problem in plane elasticity for a graded and oriented material is considered. The material property grading is intentional, whereas the property orientation or orthotropy is usually the consequence of material processing. It is assumed that the crack is located in a plane perpendicular to the direction of property grading and the principal axes of orthotropy are parallel and perpendicular to the crack. The four independent engineering constants E₁₁, E₂₂, G₁₂, and ν₁₂ are replaced by a stiffness parameter, E = √E₁₁ E₂₂, a stiffness ratio, δ = (E₁₁/E₂₂)^1/4, a Poisson's ratio, ν = √ν₁₂ ν₂₁, and a shear parameter κ₀ = (E/2G₁₂) - ν. The corresponding mixed boundary value problem is reduced to a system of integral equations which is solved for various loading conditions and material parameters. The results presented consist of the strain energy release rate, the stress intensity factors and the crack opening displacements. It is found that generally the stress intensity factors increase with increasing material inhomogeneity parameter and shear parameter and with decreasing stiffness ratio. This revised version was published online in July 2006 with corrections to the Cover Date.     

印刷品印迹前深后淡问题探讨及解决方法

详细论述了由于胶印杌印版滚筒空档角的存在使得印刷品印迹产生前深后淡的问题,分析了一般解决这个问题的方法,并且提出了自己的解决方法,在着墨辊中间增加一个过桥辊,通过计算机的仿真验证结果表明:通过增加一个过桥辊可以方便的解决印刷印迹产生.     

基于混合整数规划的工厂产品托盘打包及装箱问题研究

目的 针对工厂产品的托盘打包及装箱问题,提出一种优化产品在托盘上的布局以及托盘与产品整体在集装箱中的布局方法,以最大化集装箱的空间利用。方法 在满足现实约束的条件下,以最大化产品装载体积为目标建立混合整数规划模型。考虑问题的复杂性,本文将所研究的问题分解为2个子问题,并建立两阶段装载模型进行求解。第1阶段,建立二维集装箱装载模型,确定多种托盘类型在集装箱底面的平面布局;第2阶段,建立三维托盘装载模型,确定产品在托盘上的立体布局。鉴于精确求解该问题耗时较大,本文针对2个子问题设计两阶段启发式算法求解。为验证模型及算法的有效性,采用2组不同规模大小的算例进行测试。结果 算例结果表明,在小、大2种规模算例中,装载率平均差值分别为0和-0.5%,计算时间相差较大,本文提出的模型及算法在合理的时间内获得了最优解或近似最优解。结论 本研究能够为工厂产品的托盘打包及装箱提供快速高效的解决方案。     

水泥浆体中连续粒径粉体的堆积密度研究

为了研究粒径分布对水泥石结构与性能的影响,通过测定多组粒径分布不同的矿粉在流动度相同情况下的需水量,得到矿粉不同粒径分布所对应的不同的堆积密度,推导了浆体中连续粒径粉体的堆积密度公式。用该公式计算上述不同粒径分布的矿粉浆体的堆积密度及需水量,计算结果与试验值基本吻合。说明该公式可以用来模拟诸如水泥、磨细矿渣、粉煤灰等胶凝材料细颗粒的堆积密度。