气体软氮化

气体软氮化实质上就是在低温条件下,使碳和氮同时渗入钢表面的一种化学热处理。由于α—F_6中碳的固溶度小,气体软氮化时很快达到饱和而形成超显微的化合物,这种碳化物作为触媒剂而促进了氮化。一般气体软氮化时间为1～4小时,较氨气氮化时间大大缩短。气体软氮化可在可控气氛炉和略加改进的井式气体渗碳炉中把含有碳氮的有机物质或分别含有碳和氮的有机物质(在氮化温度范围内分解出活性碳原子和活性氨原子)通入炉内,即可进行气体软氮化。气体软氮化能提高零件的耐磨性、耐疲劳和抗咬合的性能,而且还具有不受钢种的限制及处理时间短、温度低、变形小的特点,已在模具、量刃具及一些耐磨零件中应用。     

大型调速器易磨损零件的离子氮化及变形规律研究

论述了40Cr、38CrMoAlA钢离子氮化与气体氮化不同工艺参数对性能的影响。研究结果表明,离子氮化变形小、脆性低、耐磨性高、尺寸稳定性好.并将此工艺成功地应用于125MW水轮机调速器主阀衬套产品零件上.     

无毒盐浴软氮化的应用与展望

尽管真空热处理,化学热处理和表面热处理等技术迅速发展,但传统的盐浴处理仍有其特定的优势。分析了盐浴技术的现状,综述了盐浴技术的应用,对对无毒盐浴软氮化在热处理中的应用加以展望。     

无毒盐浴软氮化的应用与展望

尽管真空热处理、化学热处理和表面热处理等技术迅速发展，蛤传统的盐浴处理仍有其特定的优势。分析了盐浴技术的现状，综述了盐浴技术的应用，并对无毒盐浴软氮化在热处理中的应用加以展望。     

铅酸蓄电池用改性氮化碳材料的研究

通过高温灼烧法制备钡掺杂氮化碳和高碳氮化碳。采用BET、SEM、XRD、EDS等手段,对这两种改性氮化碳材料的比表面积、微观形貌、物质组成和元素分布进行表征分析,并使用CV等手段对分别添加钡掺杂氮化碳和高碳氮化碳材料后的铅负极板的电化学特性进行研究。研究结果表明,制备的钡掺杂氮化碳和高碳氮化碳状态稳定,元素分布均匀,可对铅酸负极板的充放电倍率和容量性能起到增强的效果。     

软氮化工艺在电器行业中的应用

阐述软氮化工艺原理,分析它赋予被处理零件以高的耐蚀性、耐磨性、抗疲劳性、抗咬合、抗擦伤性等的机理,结合本厂引进产品的解剖实例和所生产电器产品中该工艺应用的效果,确认该软氮化工艺,可作为一种长效免维护工艺应用在电器行业中。     

热应力波对软氮化件再加热质量影响的探讨

本探讨了齿轮零件在“软氮化 局部高频感应淬火”的工艺过程中，对可能产生质量问题的因素进行了分析，指出在目前我国冶金质量现状和工业加工水平不发达的条件下，如何更进一步地从工艺合理设计方面来加强零件的生产加工质量。     

新型真空氮化热处理炉的节能效益研究

一、前言众所周知,真空热处理炉由于加热时间短和气体消耗少之故,而有显著节能效果。有资料介绍,采用真空渗碳法可以节约总耗能的30%。特别是真空氮化,由于加热温度低(520～590℃),工艺周期短,表面强化效果好,更能取到明显的节能效果。我们研制成功的 ZD 型真空氮化热处理炉,是一种适于中小厂家、大专院校、科研     

一种新型省能离子氮化炉

渗氮是对金属表面进行强化处理的常用工艺手段。离子氮化法因其独特的优点在我国应用日益广泛。但是,国内现有的离子氮化炉性能不理想,而且能耗高,本文详细介绍国外开发的一种新型省能离子氮化炉,并分析了其工作原理,以向广大读者提供参考信息。     

软氮化工艺在电器行业听应用

阐述软工艺原理,分析它赋予热处理零件以高的耐蚀性,耐磨性,抗疲劳性,抗咬合,抗擦伤性等的机理,结合本厂引进产品的解剖实例和所生产电器产品中该工艺应用的效果,确认该软件氮化工艺,可作为一种长效免维护工艺应用在电器行业中。     

基于DSP大功率中频感应焊机的研究

介绍了基于数字信号处理(DSP)设计的中频感应焊机。其中电源逆变控制采用了负载输出电流过零检测——锁相环复合控制技术，使逆变器的工作频率自动跟踪系统固有谐振频率。该电源始终能运行在负载功率因数为1的状态。     

Dielectric spectroscopy and gas chromatography methods applied on high-voltage transformer oils

This paper points out the advantages offered by the temperature dependent dielectric spectroscopy in frequency domain, as an additional diagnostic technique for insulation testing of power transformers for life-time prediction. Complex permittivity measurements have been carried out as a function of operating frequency and oil temperature for a wide selection of high voltage transformers and the gaseous byproduct concentrations were also monitored. The work correlates dielectrometry data to the gas chromatography ones.     

Progress on collisionally pumped optical-field-ionization soft X-ray lasers

We present the status of optical field ionization soft X-ray lasers. The amplifying medium is generated by focusing a high-energy circularly polarized 30-fs 10-Hz Ti: sapphire laser system in a gaseous medium. Using xenon or krypton, strong laser emission at 41.8 and 32.8 nm, respectively, has been observed. After presenting the basis of the physics, we present recent characterization of the sources as well as dramatic improvement of their performances using the waveguiding technique.     

Switching frequency determination of a bidirectional AC-DC converter to improve both power factor and efficiency

This paper investigates the possibility to optimize both the efficiency and the power factor of energy conversion systems which include power electronic converters. The values of these important power quantities depend on different parameters, such as the switching technique and the switching frequency of the power electronic elements. Comparing the already known and used switching techniques with each other we can conclude that the sPWM method offers the highest values of the efficiency and the power factor simultaneously. However, when using this technique the basic current harmonic lags as to the voltage in case of ohmic inductive loads resulting in the decrease in the power factor. In the present work a new sPWM switching technique is suggested in order to achieve higher power factor and efficiency compared to the traditional sPWM method. The aforementioned switching technique is a modified sPWM method based on an appropriate shifting of the input current to the grid voltage. But, the following question is raised: Is there a switching frequency value in a given converter topology by which both the efficiency and the power factor gain optimal value? Thus, the main aim of the present paper is determine this specific switching frequency value. This is achieved by using a simple method based on a criterion suggested in this work. In order to demonstrate how this specific frequency value can be found, a bidirectional AC-DC converter composed of a single phase bridge and two switching elements at the DC side is used. This proposed converter topology excels in that the total number of the switching elements is minimal. The study of this subject is carried out through Matlab/Simulink simulation and experimentation.     

P型环网结构的配电线载波组网方式研究

近年来,利用电力电缆屏蔽层载波通信传输配电自动化数据,是最经济、便捷和有效的一种可靠通信方式。城市小区普遍采用P型环网结构供电,采用电力电缆高频网桥耦合技术实现利用P型环网结构的电缆屏蔽层载波组网通信,是一种新的尝试,文章根据应用实例,通过现场测试多级分段电力电缆的屏蔽层信道的传输特性,分析载波组网通信效果,结果显示,利用多级分段电力电缆的屏蔽层载波通信传输配电自动化数据是可靠的。     

平均电流型Boost PFC变换器中过零畸变

有源功率因数校正变换器中,通常会使用滤波电容来吸收开关纹波和噪声。在中频(360～800Hz)应用场合,流入滤波电容的电流会变得很大。滤波电容的电流超前输入电压90°,这样功率因数就会变得很差。同时电流环在中频情况下会产生超前相位。电流环和直流滤波电容造成的超前相位致使输入电流在输入电压过零附近产生严重的畸变。通过分析输入滤波电容和电流环的影响,指出直流滤波电容是引起输入电流发生过零畸变的重要原因之一。在此基础上,采用了相位补偿的方法来补偿直流滤波电容和电流环造成的超前相位,降低了输入电流的总谐波含量,使功率因数接近为1。     

Load frequency control of an autonomous hybrid power system by quasi-oppositional harmony search algorithm

This paper deals with a novel quasi-oppositional harmony search algorithm (QOHSA) based design of load frequency controller for an autonomous hybrid power system model (HPSM) consisting of multiple power generating units and energy storage units. QOHSA is a novel improved version of music inspired harmony search algorithm for obtaining the best solution vectors and faster convergence rate. In this paper, the efficacy of the proposed QOHSA is adjudged for optimized load frequency control (LFC) of an autonomous HPSM. The studied HPSM consists of renewable/non-renewable energy based generating units such as wind turbine generator, solar photovoltaic, solar thermal power generator, diesel engine generator, fuel cell with aqua-electrolyzer while energy storage units consists of battery energy storage system, flywheel energy storage system and ultra-capacitor. Gains of the conventional controllers such as integral (I) controller, proportional–integral (PI) controller and proportional–integral–derivative (PID) controller (installed as frequency controller one at a time in the proposed HPSM) is optimized using QOHSA to mitigate any frequency deviation owing to sudden generation/load change. In order to corroborate the efficacy of QOHSA, performance of QOHSA to design optimal LFC is compared with that of other well-established technique such as teaching learning based optimization algorithm (TLBOA). The comparative performances of the HPSM under the action of QOHSA/TLBOA based optimized conventional controllers (I or PI or PID) are investigated and compared in the present work. It is found that the QOHSA tuned frequency controllers improves the overall dynamic response in terms of settling time, overshoot and undershoot in the profile of frequency deviation and power deviation of the studied HPSM.     

多通道不标定扭振测试仪研究

本文研究以普通电磁传感器为探头,利用数字电路精确同步测量出多个传感器位置处轴转动规律,再从中分析计算出各点处的扭振角度及其相位关系的微机多通道扭振测试技术,首先介绍了仪器的硬件结构,软件流程及增加测试通道的方法和限制通道容量扩大的因素,然后设计了专门的多路扭振标定信号发生器,用于研究本仪器测试多路扭振信号及其相位关系的能力,最后给出了４１０２ＢＱ型柴油机安装不同减振器时曲轴扭振规律的实测结果。     

Measurement technique for high frequency characterization of semiconducting materials in extruded cables

Knowledge on the dependence of wave propagation characteristics on material properties and cable design is important in establishing diagnostic methods for cable insulation. In this study, a high frequency measurement technique to characterize the semi-conducting screens in medium voltage cross-linked polyethylene (XLPE) cables has been developed. The frequency ranges from 30 kHz to 500 MHz. The influence of the experimental set-up, sample preparation methods, pressure and temperature are investigated. A dielectric function is developed for the semiconducting screens and this is incorporated into a high frequency model for the cable. The propagation characteristics obtained from the high frequency cable model are compared with those obtained from measurements made on the same cables.     

利用底面反射波的时频分布分析热劣化钢材的超声特性

超声无损评价中,与材料特性相关的超声参数具有频率依从性.本文提出利用回波信号时频分布得到群速度和衰减系数的方法,介绍了对Cr-Mo钢和SUS316不锈钢热劣化损伤试样的超声检测实验,对获得的底面反射波进行Morlet小波变换,在时频平面得到不同频率的衰减系数和群速度,分析比较了同一材质在不同损伤状况下的超声参数随频率变化情况.