高速开关磁阻发电机励磁参数优化控制

为了提高开关磁阻发电机高速运行时的发电效率,改善整个系统的高速运行性能,提出了一种励磁参数优化策略：以相电流有效值作为励磁参数优化指标,针对开关磁阻电机自身非线性的特点,选取使得相电流有效值最小的开通角和关断角作为优化的励磁参数,并通过曲线拟合手段对这些离散的优化参数进行处理．最后将优化的励磁参数与提出的控制算法相结合,实现了整个发电系统的优化控制．仿真和实验验证表明：该方法易于实现,整个系统不仅具有较高的发电效率,而且在负载突变时呈现出良好的调节特性．     

贵州省印江县革底滑坡基本特征及其稳定性评价

贵州所处的特殊地理环境和脆弱的地质条件,极端气候的影响,使得滑坡地质灾害频发,如何预防和治理滑坡地质灾害仍是目前面临的难题。本文通过对贵州省印江县革底滑坡基本特征的分析认为:该滑坡为一特大型旋转牵引式顺层岩土体滑坡,并形成"堰塞湖",具有滑坡边界清楚、多级滑面、滑动时间长、多次滑动、滑向转向的特点,滑面发育在奥陶系下统大湾组泥灰岩间夹泥质条带,滑床为泥灰岩、滑带土为泥质条带。通过滑坡稳定性计算,该滑坡体目前处于整体稳定状态,但"堰塞湖"仍有可能产生次生泥石流地质灾害的灾害链,威胁下游村庄和公路,最后提出了该滑坡的综合治理措施。     

一种2,5–取代的吡啶类药物中间体的合成

吡啶衍生物因其独特的化学结构,已被作为一类合成子广泛地应用于药物中间体的构建。以2,5–吡啶二甲酸二甲酯为原料,通过水解、酰化和还原等反应合成了一种新的2,5–取代的吡啶类药物中间体。     

赣方言区普通话水平测试中的语音偏误调查

本文在对赣方言区普通话水平测试成绩调查的基础上,分析了赣方言区考生常见的语音偏误,以及各等级的偏误特点,指出了调查分析结果对赣方言区普通话水平测试和普通话教学的积极作用。     

Effects of stress ratio on the temperature-dependent high-cycle fatigue properties of alloy steels

This paper addresses the effects of stress ratio on the temperature-dependent high-cycle fatigue (HCF) properties of alloy steels 2CrMo and 9CrCo, which suffer from substantial vibrational loading at small stress amplitude, high stress ratio, and high frequency in the high-temperature environments in which they function as blade and rotor spindle materials in advanced gas or steam turbine engines. Fatigue tests were performed on alloy steels 2CrMo and 9CrCo subjected to constant-amplitude loading at four stress ratios and at four and three temperatures, respectively, to determine their temperature-dependent HCF properties. The interaction mechanisms between high temperature and stress ratio were deduced and compared with each other on the basis of the results of fractographic analysis. A phenomenological model was developed to evaluate the effects of stress ratio on the temperature-dependent HCF properties of alloy steels 2CrMo and 9CrCo. Good correlation was achieved between the predictions and actual experiments, demonstrating the practical and effective use of the proposed method.     

甲基异柳磷气相色谱定量法

甲基异柳磷原油用气相色谱法测定,其色谱条件如下:不锈钢柱1m×3mm、柱内填充物为5%OV-3涂于ChromosorbW-HP60—80目担体,以氮气作载气,柱温190℃,用氢火焰检测器,癸二酸二正丁酯作内标,测定误差<±1.2%.     

RS码和P—TCM级联性能

目的 为取得较高的频带效率和较大的编码增益同时降低编码和译码复杂度。方法 将里德索罗门（ＲＳ）码与带宽有效的Ｐ－ＴＣＭ８ＰＳＫ和１６ＰＳＫ码进行级联,并在高斯信道上对其性能进行分析和计算机模拟。结果 在误比特率Ｐｂ＝１０＾－４时,级联编码系统比单个码Ｐ－ＴＣＭ系统多获得１ｄＢ编码增益,在误比特率Ｐｂ＝１０＾－７时,级联编码系统比Ｐ－ＴＣＭ系统多获得３ｄＢ编码增益。结论 随着Ｐｂ下降,ＲＳ码与Ｐ－Ｔ     

8.0kbit／sACELP声码器的GSM平台仿真

研究恶劣传输环境下８．０ｋｂｉｔ／代数码激励线性预测声码器的译码算法的改进及其在ＧＳＭ典型信道的传输性能。方法在集成软件仿真平台中引入稳信道编码模块,以消除衰落噪声和高斯噪声的影响,并完成ＡＣＥＬＰ声码器到ＧＳＭ全速率语音业务信道（ＴＣＨ／ＦＳ）的速率适配任务;在ＡＣＥＬＰ译码器中引入错误帧隐藏单元（ＥＣＵ）,以提高恶劣信道环境下的合成语音质量。结果与结论错误隐藏单元与相应的高效稳健的信道编码相结     

Influences of double aerial CO2 concentration on plant root surface area and viability and infection intensity of vesicular-arbuscular mycorrhizal fungi

Using recently developed methods for root research, an investigation initiated concerning effects of doubled atmospheric CO2 concentration on root surface area and infection of vesicular-arbuscu-lar mycorrhizal (VAM) fungi in seedlings of maize, wheat and soybean. Results showed that doubled CO2 concentration significantly extended root system surface area and promoted VAM fungal infection intensity and viability. However, interspecific variation existed in these responses. It is suggested that plant community succession would be changed due to altered characteristics of roots among species in the future climate.