静电除尘用新型脉冲高压电源研究

高压电源是静电除尘设备的关键电气部分,对提高除尘效率和减少电能消耗具有重要作用。提出了一种新型脉冲高压电源设计方法,采用高压直流叠加高压脉冲构成电源系统;之后,着重研究了高压脉冲电路的建模与分析,并通过理论分析公式得到设计参数。最后,利用MATLAB/SIMULINK仿真新型脉冲高压电源系统得到实验结果;并且通过与脉冲变压器实际产品的数据进行比对,表明了所设计方法的有效性与可行性,且对实际研发产品有一定的指导意义。     

西门子SIFUPIC F高压控制柜在转炉干法除尘中的应用

本文论述了西门子SIFUPIC F高压控制柜在唐山国丰钢铁120t转炉静电除尘中的应用。介绍了干法除尘的基本原理及在实际中的应用。利用转炉的吹炼状态,配合除尘风机及电场的振打系统,总结出了系统节电的控制方法,使用效果良好。     

高压谐振型DC-DC变换器的调压调频控制方案

为解决高压开关电源高频化过程遇到的变压器分布参数对性能影响的问题 ,采用谐振变换器技术方案 ,通过调整回路参数 ,使变换器工作在谐振状态 ,减少了系统的损耗。建立了包含 Buck变换器、谐振变换器、高压变压器和倍压整流器的直流高压开关电源系统仿真模型。通过仿真 ,分析了谐振变换器工作过程 ,研究了主回路电气参数对谐振变换器的影响。仿真说明谐振变换器工作在感性状态开关损耗较小。实验结果验证了仿真分析的正确性。     

静电除尘用高频高压功率变换器

介绍了一种应用串联谐振技术设计的静电除尘高压电源用的高频高压功率变换器,分析了主电路和控制电路的结构和工作原理,并给出了实验结果和实验波形.     

基于基金会现场总线的煤粉静电除尘系统

采用基金会现场总线技术,控制秦皇岛某港16套HD型煤粉高压静电除尘器,分析了FCS与DCS的异同,给出了基于FF的煤粉高压静电除尘系统模型、原理与实现;阐明了各个子系统的功能实现方法;多台煤粉高压静电除尘装置可应用基金会现场总线技术实现远端综合控制,具有全数字化、系统全开放、控制分散的特点,其技术经过变异可用于钢铁、石化等工业生产控制领域.     

煤输送线高压静电收尘装置

河北大学静电研究所从事静电除尘技术研究已有十几年历史 ,在工业除尘净化环境方面有多项研究成果投入实际应用 ,其中“煤输送线高压静电收尘装置”“水泥高压静电收尘装置”“工业炉窑静电消黑烟除尘装置”先后通过省级鉴定 ,两项成果获省科技进步三等奖 .这些科研成果在推广应用中取得了很好的经济和社会效益 ,为河北省的环保事业做出了突出的贡献 .煤码头是煤的转运港口 ,在煤输送线上因落差而形成了浓度极大的煤尘 .一条输送线有十余处甚至更多的落差 ,煤尘集中排放造成严重的环境污染 .其中的TSP随大气飘散 ,影响了区域性大气质量 .…     

双主动全桥变换器的高频振荡影响因素

随着新一代宽禁带半导体器件在双主动全桥(DAB)变换器中的应用,变换器交流侧出现较高的电压上升率(dv/dt)。高dv/dt含有丰富的高频谐波成分,引起变压器分布电容与系统感性元件之间产生严重的高频振荡问题。该文基于高频变压器π型三电容分布参数模型,推导了变压器端口电压高频振荡的时域解析方程,定量分析了dv/dt和变压器分布电容对高频振荡幅值的影响,并通过调节系统dv/dt实现了对高频振荡幅值的抑制。搭建了DAB变换器实验样机系统和对应的LTspice电路仿真模型,验证了高频振荡问题理论分析的合理性和正确性。     

大功率高压开关电源变压器的损耗分析及散热控制

为了提高大功率高压开关电源的可靠性和稳定性,针对其变压器损耗与温升特性,进行理论分析和仿真实例验证,并提出一种损耗分析和散热控制方法。以Ansoft Maxwell软件建立变压器的3D模型,进行磁场的有限元分析;计算不同负载条件下的温升情况及散热所需风量,通过Ansys软件对温度场进行分析;以2000V/3A的开关电源模块为例,建立实际模型验证散热控制的有效性。研究结果表明:大功率高压开关电源的变压器损耗来源于绕组损耗和磁芯损耗;在自然冷风条件下,变压器散热情况较差,温升明显过高;采用本文所述方法所计算的风量能有效控制变压器的温升;采用该方法也可得到不同负载条件下变压器的对应损耗及所导致的温升,进一步达到调控温度的目的。     

高频功率变压器研究

定量分析了高频功率变压器的激磁电感和漏感,阐述了高频功率变压器热阻与输出功率之间的关系,并提出了一种适合大功率软开关逆变器的新型功率变压器。     

高压电场节能模式改造

通过高压电场节能模式的开发,改变150T干法除尘系统的静电除尘器工作模式,降低故障率,从而达到节能降耗的目的。     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

Perspherical Approaches for Electrons in Atoms and Charged Excitons in Quantum Wells

Instead of following Fock’s expansion,we solve the Schrodinger equation for some quantum mechanical manybody systems such as electrons in atoms and charged excitons in quantum wells in a similar way in hyperspherical coordinates by expanding the wave functions into orthonormal complete basis sets of the hyperspherical hannonics(HHs)of hyperangles and generalized Laguerre polynomials(GLPs)of the hyperradius.This leads the equation to     

Advances in broadband wireless communications under high-mobility scenarios

Future mobile communication systems aim at providing very high data transmission rates, even in high-mobility scenarios such as high-speed wheel-track trains, maglev trains, highway vehicles, airplanes, guided missiles or spacecraft. A particularly important commercial application is the strong and increasing worldwide demand for high- speed broadband wireless communications （up to 574.8 km/ h test speeds or 380 km/h commercial speeds） in railways, providing data, voice and video services for applications such as onboard entertainment services to passengers, train control, train dispatch, train sensor status handling and sur- veillance. In such high-mobility scenarios, there are a number of communication challenges, including fast hand- over, location updating, high-speed channel modeling, estimation and equalization, anti-Doppler spreading tech- niques, fast power control, and dedicated network architec- ture. Because signal transmission in very high-speed scenarios will inevitably experience serious deterioration, it is imperative to develop key broadband mobile communi- cation techniques for such high-speed vehicles.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

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海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Scale-based spatial data model for GIS

Being the primary media of geographical information and the elementary objects manipulated, almost all of maps adopt the layer-based model to represent geographic information in the existent GIS. However, it is difficult to extend the map represented in layer-based model. Furthermore, in Web-Based GIS, It is slow to transmit the spatial data for map viewing. In this paper, for solving the questions above, we have proposed a new method for representing the spatial data. That is scale-based model. In this model we represent maps in three levels: scale-view, block, and spatial object, and organize the maps in a set of map layers, named Scale-View, which associates some given scales.Lastly, a prototype Web-Based GIS using the proposed spatial data representation is described briefly.     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to