基于TMS320LF2407A旋转整流器故障诊断系统的设计

为了提高无刷励磁发电机旋转整流器故障诊断系统的效果,采用TMS320LF2407A芯片作为系统的核心部件,建立了无刷励磁发电机旋转整流器故障诊断系统,讨论了系统的硬件设计,给出了硬件电路设计和部分软件编制方法.实验结果表明,该故障诊断系统具有一定的实用价值.     

鄢陵花卉园地土壤养分状况及施肥对策

本研究运用五点取样法对鄢陵花卉土壤进行定点采样,然后在室内测定了土壤有机质、土壤水分、氮、磷、钾的含量和土壤的pH值,发现了土壤中的钾元素含量较少,土壤严重缺水等问题.针对这些问题,提出了适合花卉生长的合理的管理对策,如适当协调各元素的比例,重视补充钾肥,适时灌溉等,这对于鄢陵地区花卉的种植有一定的指导意义和参考价值.     

敦煌吐鲁番文献中藏汉天文历算文化关系研究

敦煌吐鲁番出土的历史文献中,有关藏汉天文历算学方面的资料丰富,而且从中也能得知汉藏天文历算学的关系密切,尤其是在五行、纪日法、九宫、二十八宿、乘法口诀九九表、十二生肖等算法上,非常相似。由此看出,藏汉天文历算文化关系历史悠久,交流至深,这对从事研究藏汉天文历算及藏汉文化关系,具有重要的参考价值和历史意义。     

LDPC Coded TDS-OFDM for PLC Systems

Powerline communications (PLC) have drawn great interest in recent years. However, most PLC standards such as HomePlug AV use the cyclic-prefix OFDM (CP-OFDM) technology. This paper presents a broadband PLC system using low density parity check (LDPC) coded time domain synchronous OFDM (TDS-OFDM), whose spectrum efficiency is about 10% higher than that of CP-OFDM. With the same bandwidth and the ability to combat the time delay spread as HomePlug AV, this system can provide a maximum throughput of 199.7 Mbps physical layer data rate. Simulations over the measured practical powerline channel in Beijing, China, show that LDPC in the TDS-OFDM system dramatically improves the bit error rate performance, and verify the feasibility and performance of the TDS-OFDM technology for PLC systems.     

黄河三角洲贝壳堤岛中小型土壤动物群落结构

2008年5-10月,对山东省无棣县北部的黄河三角洲贝壳堤岛进行分层取样,研究中小型土壤动物群落结构.共获得各类土壤动物标本15 312头,隶属于7纲10目.结果表明:中小型土壤动物群落的主要优势类群为弹尾纲(跳虫)和蜱螨亚纲(螨类),常见类群为膜翅目,其它均为稀有类群.Shannon-Weiner多样性指数(H)为E＞C＞B＞F＞D＞A,弹尾纲和蜱螨亚纲动物个体数占该样地动物个体总数的百分比均超过40%,致使各样地的优势度指数普遍较低,最高仅为0.492 7.垂直分布显示中小型土壤动物不具有明显的表聚现象.根据Bray-Curtis相似性系数的聚类结果,可将6个样地分成3组,显示了中小型土壤动物对不同地点的响应情况.     

青岛崂山半翅目昆虫区系分析

通过对近四年崂山采集的半翅目昆虫标本的研究,共鉴定半翅目昆虫31种,隶属于7科30属,其中蝽科18种,猎蝽科4种,缘蝽科5种,异蝽科1种,蝎蝽科1种,黾蝽科1种,仰蝽科1种.区系分析结果表明崂山半翅目昆虫东洋性质显著(100%),古北性质次之(86.67%),大多数种类为东洋-古北共有种.在我国动物区系亚区水平上以华中区系和华北区系成分为主,分别占总数的100%和87.10%,与西南区(80.64%)、华南区(77.42%)联系也较为密切,东北属性稍弱(61.29%),蒙新、青藏属性最弱,分别为45.16%和38.71%.     

I-doping of anodized TiO<Subscript>2</Subscript> nanotubes using an electrochemical method

In order to obtain TiO2 with high photocatalytic activity, a cathode reduction was used to dope I⁷⁺ and I⁵⁺ into TiO₂ nanotubes of anodized Ti in C₂H₂O₄•2H₂O + NH₄F electrolyte. SEM images show that the anodization method integrated the preparation with the doping process, which for nonmetals-doping is advantageous to maintain the morphological integrity of TiO₂ nanotubes. I⁷⁺-I⁵⁺-doping enhances the UV response of TiO₂ and result in a red-shift. Under UV/visible irradiation, a I⁷⁺-I⁵⁺-doped sample (400°C) showed the highest I_ph and photocatalytic efficiency. A part of I^– in the I⁷⁺-I⁵⁺-doped sample is involved in the UV response, the red-shift and the higher I_ph.     

A parallel approach to direct resolution of albuterol

A library consisting of a series of O,O′-diaryzoyl-L-(–)-tartaric acids (2) was designed and synthesized. The substituent on the aromatic ring of 2 significantly affects the diastereomeric excess and efficiency of the resolution of racemic albuterol (1). Excellent resolving reagent 2a was selected for the resolution of rac-1 via the parallel approach. However, a family of three resolving reagents failed to improve the resolution efficiency of rac-1.     

非杆非壳大体积混凝土结构应力配筋法浅析

介绍了非杆非壳大体积混凝土结构采用应力图形进行配筋计算的原则,分析了实际应用过程中存在的一些问题,提出了一种相对简单明确的利用有限元软件按照应力直接配筋的计算方法,为工程设计人员和科研工作者提供了一种关于大体积混凝土配筋计算的思路。     

无磁仿真转台用凸轮转子马达叶片干扰力矩

介绍了一种新型的无磁仿真转台用凸轮转子连续回转电液伺服马达的工作原理及特点.通过对其叶片的系统受力分析,得出马达波动力矩产生的机理.利用Matlab软件对马达低速运行时,叶片产生的干扰力矩进行了仿真,并对不同减压阀出口油压及不同叶片厚度下的干扰力矩进行对比,得出相关参数对该类型马达力矩波动产生的影响.为解决该类液压马达存在的低速速率波动现象提供了一定的理论依据.