A goal-driven prototype column generation strategy for the multiple container loading cost minimization problem

In the multiple container loading cost minimization problem (MCLCMP), rectangular boxes of various dimensions are loaded into rectangular containers of various sizes so as to minimize the total shipping cost. The MCLCMP can be naturally modeled as a set cover problem. We generalize the set cover formulation by introducing a new parameter to model the gross volume utilization of containers in a solution. The state-of-the-art algorithm tackles the MCLCMP using the prototype column generation (PCG) technique. PCG is an effective technique for speeding up the column generation technique for extremely hard optimization problems where their corresponding pricing subproblems are NP-hard. We propose a new approach to the MCLCMP that combines the PCG technique with a goal-driven search. Our goal-driven prototype column generation (GD-PCG) algorithm improves the original PCG approach in three respects. Computational experiments suggest that all three enhancements are effective. Our GD-PCG algorithm produces significantly better solutions for the 350 existing benchmark instances than all other approaches in the literature using less computation time. We also generate two new set instances based on industrial data and the classical single container loading instances.     

容器内爆炸多传感器测试系统的原理设计与应用

为对炸药爆炸进行测量和监控,出于安全以及测试方便考虑,试验需要在爆炸容器中进行。由于测试任务的需要,试验中使用的传感器的类型及数量较多,包括各种压力传感器、应变传感器以及爆速传感器等,因此构建一个多传感器的测量系统就显得十分重要。文章给出了试验容器的基本结构,介绍了钢筒内化爆试验爆炸冲击波压力测试系统的原理设计与应用,构建了传感器、起爆和同步触发、爆速监测以及数据采集存储几个主要部分组成的测试系统,并对系统几个主要组成部分进行了详细的阐述。压杆测压解决了高压测量中的测量困难以及传感器使用效率低的问题,取得了良好的实际应用效果。     

Nonlinear Input-Shaping Controller for Quay-Side Container Cranes

Input-shaping is one of the most practical open-loop control strategies for gantry cranes, especially those having predefined paths and operating at constant cable lengths. However, when applied to quay-side container cranes, its performance is far from satisfactory. A major source of the poor performance can be linked to the significant difference between the gantry crane model and the quay-side container crane model. Gantry cranes are traditionally modeled as a simple pendulum. However, a quay-side container crane has a multi-cable hoisting mechanism.In this paper, a two-dimensional four-bar-mechanism model of a container crane is developed. For the purpose of controller design, the crane model is reduced to a double pendulum with two fixed-length links and a kinematic constraint. The method of multiple scales is used to develop a nonlinear approximation of the oscillation frequency of the simplified model. The resulting frequency approximation is used to determine the switching times for a bang-off-bang input-shaping controller. The performance of the controller is numerically simulated on the full model of the container crane, and is compared to the performance of similar controllers based on a nonlinear frequency approximation of a simple pendulum and a linear frequency approximation of a constraint double pendulum. Results demonstrate a superior performance of the controller based on the nonlinear frequency approximation of the constraint double pendulum.The effect of the oscillation frequency on the controller performance is investigated by varying the model's frequency around the design value. Simulations revealed that the performance of the controller suffers serious degradation due to small changes in the model frequency. To alleviate the shortcomings of the input-shaping controller, a delayed-position feedback controller is successfully applied at the end of each transfer maneuver to eliminate residual oscillations without affecting the commands of the input-shaping controller.     

一类发烟装液弹装填率的数学模型

装液弹的装填率对弹的安全可靠性极其重要 .如果装液弹的装填率不合理 ,不是造成弹腔容积的浪费 ,就会造成弹内压过大 ,易于破坏密封性能引起渗漏甚至破裂而造成损失和危险 .本文通过对一类发烟装液炮弹弹内压力分析 ,得出了弹内压力计算公式 .在分析压力诸因素时 ,我们运用了固体热膨胀理论 ;考虑了液体的压缩性 .这是本文区别于以往压力计算的两个特点 .通过这类发烟装液炮弹内压压力曲线的分析 ,导出了装液 (炮 )弹弹腔空隙率合理选定最后的数学模型 (PLT方程——可由此确定合理的装填率 ) ,由此所计算的空隙率数据与国外文献值相符 ,并引入了“预极限温度”的概念 .可以相信 ,所谓“预极限温度”,将是装液 (炮 )弹 (或任何装液容器 )设计者必须认真考虑的问题     

The Inner Phase of Molecular Container Compounds as a Novel Reaction Environment

The conceptual idea of molecular container compoundsand their synthesis has opened an entirely new andvery interesting research field: the chemistry of andwithin molecular container compounds and theircomplexes. Molecular containers have inner phases justlarge enough to accommodate a single guest molecule.Beginning with Donald J. Cram's first synthesis of acarcerand, which permanently entrapped a single guestmolecule, many other containers such ashemicarcerands, molecular lantern, self-assembledcapsules and fullerenes have been synthesized andstudied. Not only is the design and development of newcontainer compounds an ongoing challenge for organicchemists, but also the systematic investigation ofchemical reactions within their inner phases. Theresults of a large variety of inner phase reactionsspanning acid-base, reduction, oxidation, nucleophilicsubstitution, addition, thermal, photochemical andpericyclic reactions have provided us with moreinsight into the relationship between bulk phase andinner phase reactants and the mechanism of thetransfer of electrons and photons through theinsulating shell of a container molecule. They havealso led to very spectacular applications of molecularcontainer compounds such as the stabilization ofreactive intermediates by incarceration. Thesehighlights of inner phase chemistry and the currentefforts and successes towards using molecularcontainers as catalytic reaction vessels are presentedand discussed.     

Order Reduction of General Nonlinear DAE Systems by Automatic Tearing

The object-oriented approach to modelling has recently made possible to build models of large-scale real systems. However, the resulting system of equations is generally a nonlinear DAE (Differential Algebraic Equations) system of large dimension, which must be reduced in some way to make it tractable for numerical solutions. A way to do this is automatic symbolic tearing, which aims at splitting the DAE system into two parts: a core consisting of a reduced implicit DAE system and a set of explicit assignments. The problem is here dealt with by a graph theoretic approach, first proving the NP-completeness in the general case, then formulating the problem with reference to a bipartite graph and finally defining an efficient and flexible algorithm for automatic tearing. It is also shown how the proposed algorithm can easily incorporate both general and domain-specific heuristic rules, and can also be used to deal with equations in vector form. The application to serial multibody systems is considered as a significant example.     

Modelling of dynamic interaction between structure and trolley for mega container cranes

This article deals with the analysis of trolley impact on the dynamic behaviour of the flexible structure of the mega quayside container crane (QCC) boom, identified as the most relevant structural part. It develops a modelling method for the dynamic response of the large flexible structure of the QCC boom under a moving trolley. By using FEM the original structure of the whole crane structure is reduced to an equivalent model of the boom. The boom is in this way modelled as a system with distributed parameters, comprising reduced stiffnesses and lumped masses from other parts of the upper structure. The article looks at the moving mass approach to achieve the desired performance of the QCC. Differential equations of the mathematical model are obtained by using Lagrange's equations and the assumed mode method. The continuum is discretized by a finite number of admissible functions. Deterministic simulation gives the dynamic response of the boom for quay-to-ship container transfer. Results are obtained for the boom deflection and bending moment values, as well as for the dynamic amplification factor of deflection.     

Sonochemical Synthesis of Magnetic Protein Container for Targeted Delivery

A new targeted delivery system was developed in this paper by depositing magnetic NPs on protein containers which were prepared by sonicating oil in a protein solution. The deposition was conducted by layer‐by‐layer technique and monitored by zeta potential measurement. Such prepared samples can be targeted delivery in an external magnetic field. The hydrophobic dye TPP, as a model of drug, was loaded in the containers by dissolution in the oil phase before sonication. The containers loaded with dye are stable and can sustain the deposition treatment without loss of dye due to the protection of protein nanoshells.

     

Benchmarking the operating efficiency of Asia container ports

The aim of this paper is to explore the operating efficiency, the scale efficiency targets, and the variability of DEA efficiency estimates of Asian container ports. This study applies data envelopment analysis (DEA) with the traditional DEA model, most productive scale size concept, returns to scale approach, and bootstrap method to assess the operating performance, set scale efficient targets, and determine efficiency rankings of Asian container ports. The results of this study can provide port managers with insights into resource allocation, competitive advantages, as well as optimization of the operating performance. The potential applications and strengths of DEA in assessing the Asian container ports are highlighted.