Daofang Chang

Simulation-based heuristic method for container supply chain network optimization

We propose a novel idea that considers optimization problem of multi-echelon container supply chain network.We develop a mixed integer programming model to minimize the total container supply chain service cost.We propose a simulation-based heuristic method to efficiently solve the problem. With the emerging of free trade zones (FTZs) in the world, the service level of container supply chain plays an important role in the efficiency, quality and cost of the world trade. The performance of container supply chain network directly impacts its service level. Therefore, it is imperative to seek an appropriate method to optimize the container supply chain network architecture. This paper deals with the modeling and optimization problem of multi-echelon container supply chain network (MCSCN). The problem is formulated as a mixed integer programming model (MIP), where the objective is subject to the minimization of the total supply chain service cost. Since the problem is well known to be NP-hard, a novel simulation-based heuristic method is proposed to solving it, where the heuristic is used for searching near-optimal solutions, and the simulation is used for evaluating solutions and repairing unfeasible solutions. The heuristic algorithm integrates genetic algorithm (GA) and particle swarm optimization (PSO) algorithm, where the GA is used for global search and the PSO is used for local search. Finally, computational experiments are conducted to validate the performance of the proposed method and give some managerial implications.

Mechanical Property Improvement of Carbon Fiber-Reinforced PTFE Composites by PA6 Filler Dispersion

Mechanical properties of carbon fiber reinforced composites and polyamide6 (PA6) particles dispersed carbon fiber hybrid-reinforced composites were investigated. Mechanical properties were improved by incorporating PA6 particles into the PTFE matrix. Hybridization effects on the mechanical properties of carbon fiber reinforced-PTFE composites with PA6 particles are discussed. In the present experiment, an attempt has been taken to disperse PA6 particles into carbon fiber-reinforced composites (CFRP) matrix to fabricate carbon fiber-reinforced hybrid composites (CFHRP). The main purpose of hybridization is to optimize the properties of the matrix for high performance fiber-reinforced composites.

The Friction and Wear of Aramid Fiber-Reinforced Polyamide 6 Composites Filled with Nano-MoS2

The friction and wear behaviors of aramid-filled PA 6 composites filled with and without nano-MoS2 were investigated on an end-face tribometer through rubbing against ASTM 1045 steel under dry friction. The experimental results indicated that the wear rate and the friction coefficient of PA 6 decreased with the addition of nano-MoS2. The friction coefficients of PA 6 composites filled with aramid fiber are lower than those without nano-MoS2. The main wear mechanisms under dry sliding condition are the plastic deformation and mechanical microploughing. For best combination of friction coefficient and wear rate, the optimal volume content of MoS2 in the composites appears to be 10 vol %.

Study on the Interfacial Behavior of Clay-Coated Carbon Fiber-Reinforced PEI Composites

In this article, based on the surface chemical treatment of carbon fiber, a clay coating process was developed for the surface modification of the carbon fiber to obtain a controlled interface between carbon fiber and polyetherimide (PEI) matrix in the composites system. SEM, XPS spectrum and contact angle measure reveal that the clay coating can improve the surface roughness of the carbon fiber surface for a favorable wettability with the matrix, which can also improve the interfacial adhesion of the composites. Experimental results show that the interlaminar shear strength (ILSS) and the three-point bending (TPB) of the composites reinforced by the carbon fiber coated with the clay have been enhanced.

The mechanical and tribological properties of grafted LDPE-filled SiO2/PTFE composite

In this article, low-density polyethylene (LDPE) rubber and silica (SiO2) particles were employed to modify polytetrafluorethylene (PTFE) simultaneously. The distribution and dispersion of LDPE and SiO2 particles in PTFE matrix can be adjusted by the wettability of SiO2 particles toward PTFE and LDPE, so as to achieve a simultaneous enhancement of toughness and modulus of PTFE. A unique structure with the majority of PTFE surrounded by SiO2 particles was first observed using maleic anhydride (MAH)-grafted LDPE, resulting in a dramatical increase in Izod impact strength as the rubber content in the range of brittle–ductile transition (4–16 wt%). The friction and wear properties were obviously improved with the addition of MAH-grafted LDPE regardless of the content of SiO2.

The Effect of Arylboronic Acid Treatment of Carbon Fiber on the Mechanical and Tribological Properties of PA66 Composites

PA66 composites filled with surface-treated carbon fiber were prepared by twin-screw extruder in order to study the influence of carbon fiber surface arylboronic acid treatment on the mechanical and tribological behavior of the PA66 composites (CF/PA66). The mechanical property, friction and wear tests of the composites with untreated and treated carbon fiber were performed and the worn surface morphology was analyzed. The results show that the worn surface area of the treated carbon fiber was far smoother than that of the untreated carbon fiber and there formed a bonding adhesion on the carbon fiber surface after treatment. The tensile strength of CF/PA66 composites with surface arylboronic acid treatment was improved. The friction coefficient and wear of arylboronic acid treated CF/PA66 composites were apparently lower than that with untreated carbon fiber. In conclusion, the surface treatment favored the improvement of the higher interface strength and so had good effect on improving the tribological properties of the composites.

The Mechanical and Tribological Properties of Anodic Oxidation Treatment Carbon Fiber-Filled PU Composite

The interfacial adhesion of the carbon fiber (CF) reinforced polyurethane (PU) composite was improved by the means of anodic oxidation treatment. The mechanical and reciprocating sliding wear properties were studied and results showed that the anodic oxidation treatment have definitely improved the mechanical strength. And the wear and the friction coefficient of PU decreased with the addition of CF. The friction coefficients of anodic oxidation treated CF/PU composites are lower than those of PU and CF/PU composite. The interfacial adhesion between the CF and PU dominated the main wear mechanisms.

An Improved Particle Swarm Optimization Algorithm for Solving Dynamic Tugboat Scheduling Problem

The dynamic tugboat scheduling problem is a special kind of Job Scheduling Problem. Here we propose an improved particle swarm optimization (PSO) algorithm in which an entropy function and an elite set is used for better performance. When the entropy of the swarm keeps under some value in a certain period, some of the particles will be replaced randomly by those from the elite set. This may help the swarm to get rid of local optima, and to have a faster convergence. The proposed algorithm is successfully used in the tugboats scheduling problem, and demonstrated its advantages of faster convergence and better result than the standard PSO.

Dynamic rolling strategy for multi-vessel quay crane scheduling

Abstract This paper focuses on the container loading and unloading problem with dynamic ship arrival times. Using a determined berth plan, in combination with the reality of a container terminal production scheduling environment, this paper proposes a scheduling method for quay cranes that can be used for multiple vessels in a container terminal, based on a dynamic rolling-horizon strategy. The goal of this method is to minimize the operation time of all ships at port and obtain operation equilibrium of quay cranes by establishing a mathematical model and using a genetic algorithm to solve the model. Numerical simulations are applied to calculate the optimal loading and unloading order and the completion time of container tasks on a ship. By comparing this result with the traditional method of quay crane loading and unloading, the paper verifies that the quay crane scheduling method for multiple vessels based on a dynamic rolling-horizon strategy can provide a positive contribution to improve the efficiency of container terminal quay crane loading and unloading and reduce resource wastage.

Impact of Policy Adjustment on the Port Performance: the Case of Shanghai Port

Despite the interest shown by many authors in port management, only a few contributions have tried to evaluate the relative impact of policy adjustment on the port performance. Based on the literature reviews, a statistical approach was adopted to measure the impact of policy adjustment on economic, operational and governance performance. The sampled harbor districts cover over 44 % of the annual operated container volume in Shanghai Port. Empirical outcomes reveal that a strong positive relationship between economic indicators and operational indicators, and a negative relationship between economic/operational indicators and governance performance. This article, by addressing the complexity and diversification of variables affecting the port performance, provides an exploratory contribution on the policy research in the literature.