微波辐射消毒根管的效果研究

目的 本实验采用固定微波频率、治疗时间 ,变动功率、治疗次数的方法 ,通过消毒前后根管内细菌培养结果 ,评价和筛选最佳消毒参数组合 ,为临床上使用微波消毒治疗牙髓病及根尖周病提供参考依据。方法 选择根管通畅的前牙和前磨牙共 6 0颗作为研究对象 ,选择不同参数的微波辐射消毒根管。消毒前后作根管内细菌培养。结果 利用微波消毒根管的最佳参数组合是输出功率 30～ 40W ,每次照射时间 5秒 ,重复 2～ 3次。结论 微波作为物理性根管消毒方法之一 ,适用于根管通畅的患牙 。

适用于风力发电设备的电力稳定装置

由于风力发电机的功率变动导致电力系统的频率波动。为确保系统的电能质量,本文阐述了功率变动缓和控制性电力稳定装置的组成结构与工作原理,并对风力发电功率平稳化效果进行验证的试验装置。予以介绍。

Principle and characteristics of original hydraulic traction drive CVT

A new CVT(continuously variable transmission) design which is a traction drive variator has been introduced. Analytical predictions and experimental results of the steady state which demonstrate higher efficiencies and power capacities of the new design are presented. The traction and power loss are then predicted by using models including evaluation of creep and spin in the contact patch. Analytical predictions of the transmission reach reasonable agreement with the experimental data, and the transmission efficiency of the system increases as the input torque increases while the input speed is certain. The research results can be further used in hydraulic traction drive CVT design and optimization.

A New Topology of a Variable Output-Voltage DC-DC Converter for Fuel Cell Vehicles

The aim of this paper is to present a new topology of a DC-DC power converter for conditioning the current and voltages behaviors of embarked energy sources used in electrical vehicles. The fuel cells in conjunction with ultra-capacitors have been chosen as the power supply. The originality of the proposed converter is to use a variable voltage of the DC bus of the vehicle. The goal is to allow a better energy management of the embedded sources onboard the vehicle by improving its energy efficiency. After presenting and explaining the topology of the converter, some simulation and experiments results are shown to highlight its different operation modes.

High-Power-Factor Adjustable Speed Drive Using Diode Clamped Multilevel Inverter

This paper presents a new approach to alleviate the harmonics and to enhance the power factor of the ASD （adjustable speed drive）. A conventional ASD with 2-level PWM （pulse width modulation） inverters generate high dv/dt and high frequency common mode voltages which are harmful for the drive applications. It reduces the motor bearings life and conducted EMI （electro magnetic interference） deteriorates the insulation. In this paper, a diode clamped multilevel （3-level） inverter is used to perform dual task. It generates HF （high frequency） current to be injected at the input of the three-phase front-end rectifier thereby improving the harmonic spectra and the power factor. It also drives the induction motor. The salient feature of this paper is that it does not require separate converters for improving power factor and to drive induction motor. Furthermore, inverter switches operate with ZVS （zero voltage switching）, thus reducing the switching losses substantially, The voltage stress of the switches also has been reduced to half of the conventional 2-level converter. The inverter is operated with SPWM （sinusoidal pulse width modulation） technique. The simulation results for a prototype of 2.2 kW are presented.

适用于风力发电设备的电力稳定装置

由于风力发电机的功率变动导致电力系统的频率波动。为确保系统的电能质量，本文阐述了功率变动缓和控制性电力稳定装置的组成结构与工作原理，并对风力发电功率平稳化效果进行验证的试验装置予以介绍。

HEART RATE VARIABILITY DURING HIGH-INTENSITY EXERCISE

The aim of this paper is to describe and analyse the behaviour of heart rate variability(HRV)during constant-load,high-intensity exercise using a time frequency analysis(Wavelet Transform).Eleven elite cyclists took part in the study(age:18.6±3.0 years;VO_(2max):4.88±0.61 litres·min^(-1)).Initially,all subjects performed an incremental cycloergometer test to determine load power in a constant load-test(379.55±36.02 W;89.0%).HRV declined dramatically from the start of testing(p<0.05).The behaviour of power spectral density within the LF band mirrored that of total energy,recording a significant decrease from the outset LF peaks fell rapidly thereafter,remaining stable until the end of the test.HF-VHF fell sharply in the first 20 to 30 seconds.The relative weighting(%) of HF-VHF was inverted with the onset of fatigue,[1.6%at the start,7.1(p<0.05) at the end of the first phase,and 43.1%(p<0.05) at the end of the test].HF-VHF_(peak) displayed three phases:a moderate initial increase,followed by a slight fall,thereafter increasing to the end of the test.The LF/HF-VHF ratio increased at the start,later falling progressively until the end of the first phase and remaining around minimal values until the end of the test.

Fusion Energy and Stopping Power in a Degenerate DT Pellet Driven by a Laser-Accelerated Proton Beam

In this paper, we have improved the fast ignition scheme in order to have more authority needed for highenergy-gain. Due to the more penetrability and energy deposition of the particle beams in fusion targets, we employ a laser-to-ion converter foil as a scheme for generating energetic ion beams to ignite the fusion fuel. We find the favorable intensity and wavelength of incident laser by evaluating the laser-proton conversion gain. By calculating the source-target distance, proton beam power and energy are estimated. Our analysis is generalized to the plasma degeneracy effects which can increase the fusion gain several orders of magnitude by decreasing the ion-electron collisions in the plasma.It is found that the wavelength of 0.53 μm and the intensity of about 1020W/cm^2, by saving about 10% conversion coefficient, are the suitable measured values for converting a laser into protons. Besides, stopping power and fusion burn calculations have been done in degenerate and non-degenerate plasma mediums. The results indicate that in the presence of degeneracy, the rate of fusion enhances.