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Sun T.,Anhui Polytechnic University
International Journal of Applied Electromagnetics and Mechanics

In order to improve recycling quality of asphalt mixtures based on microwave heating, thermoelectric coupling theory is researched. Heat conduction equation is built according to Fourier's Law. Series model, parallel model and Maxwell model are studied to solve thermal conductivity of asphalt mixtures. Radiation field model of pyramidal horn antenna is set up and mean value of electric field intensity is measured by experiment. Thermoelectric coupling model is built on the basis of dielectric property of asphalt mixtures. Numerical simulation is performed for the model. It is found that influence of asphalt-aggregate ratio on temperature field is not distinct. Average temperature of asphalt mixtures is related to microwave power and increases with microwave power linearly. The asphalt mixtures using diorite as aggregate have a strongest adsorption capability to energy. The result can simulate hot in-place regeneration process, and has important significance to improve regeneration quality of asphalt mixtures. © 2013 IOS Press. Source

Zhang L.,University of Bridgeport | Xiang J.,Anhui Polytechnic University
Energy Conversion and Management

In a heat-power system, the use of distributed energy generation and storage not only improves system's efficiency and reliability but also reduce the emission. This paper is focused on the comprehensive performance evaluation of a grid-tied microgrid, which consists of a PV system, a hydrogen fuel cell stack, a PEM electrolyzer, and a hydrogen tank. Electricity and heat are generated in this system, to meet the local electric and heat demands. The surplus electricity can be stored as hydrogen, which is supplied to the fuel cell stack to generate heat and power as needed. The performance of the microgrid is comprehensively evaluated and is compared with another microgrid without a fuel cell stack. As a result, the emission and the service quality in the first system are higher than those in the second one. But they both have the same overall performance. © 2014 Elsevier Ltd. All rights reserved. Source

Liu Y.,Anhui Polytechnic University
Journal of Mechanical Science and Technology

Gear shaping is an efficient cutting method available for internal helical non-circular gears, but gear hobbing is not. Four methods and models of generating motion were built. Virtual shaping revealed that the method of equal arc-length of gear billet has the highest machining precision. Three methods of primary motion were built and analyzed respectively by using a kinetic simulation, which revealed that the method of keeping a constant velocity has the best dynamic performance. Two methods of additional motion were offered. Virtual shaping revealed that the two methods have the same precision, whether the gear has a right-hand helix or left-hand helix. Finally, two optimal shaping models were provided, and performed shaping experiments, respectively. The experiments showed that the shaping strategies and models are correct and feasible. Tooth-flank detections revealed that every tooth of the gears has the same precision using the optimal shaping models. © 2014 The Korean Society of Mechanical Engineers and Springer-Verlag Berlin Heidelberg. Source

Liu Y.,Anhui Polytechnic University
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science

As an efficient manufacturing method for gears, shaping technology developed for non-circular helical gears will greatly break through the dilemma of their applications; especially for those gears with part of pitch curves being concave, being not able to be hobbed. Two fundamental linkage-models for external non-circular helical gears were built based on the meshing theory of non-circular gears in this article. According to four linkage methods in plane and two kinds of additional rotation in vertical direction, eight shaping strategies and their practical linkage-models (1)-(8) were developed. Taking a three-order elliptic helical gear as an example, the kinematic characteristics of the eight practical linkage-models were analyzed, which reveals that equal arc-length of gear billet (models (3) and (4)) have the highest accuracy under a given efficiency. The dynamic characteristics of models (3) and (4) were analyzed, which shows that model (4) (equal arc-length of gear billet and additional rotation on shaper cutter) is better in performance, and is an optimal one. The optimal linkage-model was demonstrated to be valid by a virtual shaping, and be able to shape those non-circular helical gears with part of pitch curves being concave. Moreover, the accuracy among every gear tooth is uniform. The theory developed and the results of the virtual shaping were illustrated with a shaping experiment. The train of thought and the results will be useful for any external non-circular helical gears with free pitch curves. © IMechE 2014. Source

This article first describes a class of uncertain stochastic control systems with Markovian switching, and derives an Itô-Liu formula for Markov-modulated processes. We characterize an optimal control law, that satisfies the generalized Hamilton-Jacobi-Bellman (HJB) equation with Markovian switching. Then, by using the generalized HJB equation, we deduce the optimal consumption and portfolio policies under uncertain stochastic financial markets with Markovian switching. Finally, for constant relative risk-aversion (CRRA) felicity functions, we explicitly obtain the optimal consumption and portfolio policies. Moreover, we make an economic analysis through numerical examples. Copyright © 2014 Taylor & Francis Group, LLC. Source

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