braking resistor of hybrid electric armored vehicle

Abstract-In the present paper, the heat transfer process of the braking resistor is analyzed. The corresponding theoretic model is proposed and solved numerically. The standard laminar model and constant heat flux method are employed to compute the heat transfer in the parallel channels between the braking resistor strips. The numerical computations for different conditions are performed. The corresponding heat transfer relationships among the convective heat transfer coefficient, thermal boundary layer thickness, cooling air outlet temperature and braking resistor surface temperature are studied according to the computed results. Finally, the theoretical heat transfer model of flow in the braking resistor case is used to investigate the variety of the resistor temperature of the practical braking resistor applied in some type hybrid electric armored vehicle. The vehicle operating test result shows that the uncertainty of the theoretic calculation model is within 15%, which can fulfill the engineering design requirement. Keywords- Braking Resistor; Heat Transfer; Hybrid Electric Armored Vehicle

 1. INTRODUCTION 

Compared to traditional vehicle, the regenerative braking of hybrid electric vehicle is a mainly trait. Regenerative braking is a kind of braking process in which the inertial energy generating from vehicle running is passed to the motor by transmission system and then the motor working as a generator uses the electric energy to charge the batteries, as seen in Fig. 1. In this process, the braking energy is used efficiently, which could decrease the energy consuming and increase the fuel saving. In the present study of hybrid electric vehicle technology, regenerative braking becomes an effective method to increase energy saving and continuous operating mileages. In the high intensity braking or continuous braking process, the electric energy recycled can not be fully absorbed because of the capability limitation of the energy storing components such as batteries. Under this circumstance, the braking resistor should be applied to consume the surplus energy in order to assure the safety and reliability of vehicle, as seen in Fig. 1. There are many rigorous operating conditions such as high speed braking, long slope continuous braking and so on in the hybrid electric armored vehicle (HEA V). So much higher requirement on safety and reliability is proposed for the components in HEAV.

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Transistor equivalent circuits

This paper surveys the history of the electric-circuit representation of the transistor over the past fifty years. During the first two decades after the transistor was announced in 1948, primary emphasis was on small-signal equivalent circuits, which could be used for linear-circuit analysis and design. In addition, parameters of many of these equivalent circuits for the bipolar junction transistor, which are described, were related to the physical construction of the device. Approximately two-thirds of the paper is devoted to this period, when the writer personally contributed to this effort. By the beginning of the third decade, transistor circuits had became more complex, and circuit analysis was carried out with the help of digital computers. Interest then shifted away from small-signal equivalent circuits to “models” for computer-aided circuit design (CACD). This transition, including the models used in the widely used CACD program SPICE, is described. MOS transistors are treated only briefly; by the time MOS transistors became commercially viable devices, emphasis then also had shifted to “models” for CACD. In conclusion, the writer notes that there is still hope for us aficionados of small-signal equivalent circuits; new types of transistors are still being characterized in this manner!

I. INTRODUCTION

When I was first invited to prepare a paper on transistor equivalent circuits for this transistor anniversary issue, I

was delighted—after all, that topic played an important part in my professional life for nearly a decade in the mid-1950’s. Then, on further reflection, I recognized that transistor equivalent circuits do not play nearly so significant a role today as they did in that time period because of changes in transistor and computer technology over the intervening years. So why should we write about equivalent circuits? In addressing that question, I conclude that a historical review of the changing role of the equivalent circuit over these five decades—as presented here—should make an interesting paper for our younger readers, and perhaps provide a bit of nostalgia for the rest of us.

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Transistor current-switching circuits

Transistor current-switching circuits

In recent years, the transistor has replaced the vacuum tube for most switching applications and there are various types of high-speed switching circuits.1 A very useful class of switching circuits known as current-switching circuits or current-mode logic (c.m.l.) circuits has been devised by Yourke.2 This type of switching circuit, which avoids the satura- tion region and hence the hole storage phenomenon associated with it, uses low voltage swings and low impedance levels. It fully utilizes the inherent band- width of the triode and attains very high switching speeds approaching to the theoretical minimum rise and fall times for a given transistor. A number of modi- fications3 ' 4*5j 6 have been suggested to simplify the logical operation and circuit techniques and a num- ber of advantages have been described in the literature for this type of circuitry. Investigations have shown that the current-switching circuit possesses the follow- ing disadvantages: (1) Relatively large number of transistors required. (2) Large number of power supplies required. (3) Stringent tolerance requirements of the com- ponents and the power supplies used in the circuits. (4) Large power dissipation in transistors. The purpose of this paper is to point out the limitations of the circuits proposed previously to show that most of the above-mentioned disadvantages can be over- come by suitable circuit modifications; further, a more detailed analysis and design philosophy and the experimental results of the c.m.l. circuits is presented.

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the Questions of Countryside Electronic-Commerce and the Pattern of Innovation

Research on the Questions of Countryside Electronic-Commerce and the Pattern of Innovation.
This is my First article about Electronic.

Abstract—As representative of industry and service industry' Chinese city E-commerce develop like a raging fire actually, but agriculture electronic commerce appears development with difficulty. The countryside electronic-commerce's development has some problems, how can we solve these problems? This article begin with the functions of reconstruction of electroniccommerce in rural and based on the agriculture electroniccommerce's challenges, we proposed the new pattern of the agriculture electronic-commerce of F to C to B. we hope to can explore an appropriate path of the agriculture electroniccommerce and make contributions for our country electroniccommerce in the countryside development. As representative of industry and service industry 'Chinese city electronic-commerce develop like a raging fire actually, but agriculture electronic commerce appears development with difficulty. The countryside electronic-commerce's development has some problems, how can we solve these problems? This article begin with the functions of reconstruction of electronic-commerce in rural and based on the agriculture electronic-commerce's challenges, we proposed the new pattern of the agriculture electronic-commerce of F to C to B. we hope to can explore an appropriate path of the agriculture electronic -commerce and make contributions for our country electronic-commerce in the countryside development.

I. E-COMMERCE IN THE ROLE OF NEW RURAL CONSTRUCTION
E-commerce, including agricultural production, agricultural management, agricultural marketing, electronic payment, logistics management and customer relationship management, labor export services, agricultural support, health services, entertainment services and so on. Its role is as follows.

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