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Liang C.,Hebei University of Technology | Li H.,Hebei University of Technology | Wang L.,Academy of Military Transportation | Chen X.,Hebei University of Technology | Zhao W.,Hebei University of Technology
Materials Chemistry and Physics | Year: 2010

The cytotoxicity of carbon nanotubes adhered on hydroxyapatite matrix synthesized by catalytic chemical vapor deposition was investigated towards mouse fibroblast cells, using MTT assay method. The results demonstrate that carbon nanotubes adhered on hydroxyapatite matrix possess no evident short-term toxicity and can be considered biocompatible with L929 mouse fibroblast cells in culture, while the long-term negative effects, that are evidenced after reseeding, are probably due to physical rather than chemical interactions. © 2010 Elsevier B.V. All rights reserved.

Zhao J.,Tianjin University | Zhao J.,Tianjin Polytechnic University | Tang W.,Tianjin University | Wei J.,Academy of Military Transportation
International Journal of Production Economics | Year: 2012

This paper studies the pricing problem of substitutable products in a supply chain with one manufacturer and two competitive retailers. The consumer demands and manufacturing costs are of uncertainty, which are described by fuzziness. Based on different market structures, one centralized pricing model and three decentralized pricing models are developed, and the corresponding analytical equilibrium solutions are obtained using the game-theoretic approach. Finally, numerical examples are presented to illustrate the effectiveness of the theoretical results, and to gain additional managerial insights. © 2010 Elsevier B.V. All rights reserved.

Pang G.,Academy of Military Transportation
Proceedings of the 2011 Chinese Control and Decision Conference, CCDC 2011 | Year: 2011

In this paper, the optimal strategy of transnational supply chain is analyzed when the demand distribution and market exchange rate are fluctuated by emergencies. The optimal order quantity of assembly transnational corporations and the trade price of parts supplier are changed under the market demand changed larger or less. The conclusions show that the supplier will adjust his production plan properly when the demand scale and market exchange rate are changed larger. This paper also reveals that the wholesale price will increase as market demand increases and the wholesale price will decrease as market demand decreases. An interesting economic insight is that the production plan is not usually adjusted. © 2011 IEEE.

Li N.,Tianjin University | Li N.,Tianjin Institute of Urban Construction | Wang S.,Tianjin Institute of Urban Construction | Li Y.,Academy of Military Transportation
Journal of Computational Information Systems | Year: 2011

The vehicle routing problem (VRP) with constraint is an important problem in distribution and transportation. This paper presents a combination study of genetic algorithms (GA) and ant colony optimization (ACO) applied in the vehicle routing problem. This study starts with a literature review of the GA and ACO application for different problems. Then the objective function and constraint of VRP is set up, the objective is to minimize the servicing cost without exceeding the capacity of the vehicles. In the proposed GA-ACO algorithm, genetic algorithm is conducted through selection, crossover and mutation, and then pheromone update of ACO is performed to move out of local optima. The proposed GA-ACO algorithm is to enhance the performance of genetic algorithm by incorporating local search and ant colony optimization. From simulation results, it is shown that the proposed GA-ACO algorithm has satisfactory performance. © 2011 Binary Information Press December, 2011.

Yang G.,Tianjin Polytechnic University | Li Y.,Academy of Military Transportation | Yu L.,Tianjin Polytechnic University
Diangong Jishu Xuebao/Transactions of China Electrotechnical Society | Year: 2013

Low-frequency noise can be used to measure the noise power spectrum of the LED device, Which can allow to test and analyze the defect states of the device structure in depth. This test has a good prospect, which not only has the advantages of no damage to the device and rapid measurement, but also reflects the internal characteristics of the device structure itself. This paper systematically describes the low-frequency noise generation mechanism and the mathematical model, and introduces comprehensively the research results of the 1/f and GR noise power spectral characterization based on GaN and GaAs LED devices. From the low-frequency noise characteristics of LED it can be observed that LED's performance can be tested and analyzed by 1/f and G-R noise power spectrum. And the origin affecting the life of the LED device is mainly due to dark spots in active region and defect states inside and outside the active region. The mechanism that dark spots and defect states impact the decay of LED has not yet been determined.

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