加权系数平均法改进的小波域LMMSE信道估计算法

针对传统LMMSE算法需要知道信道特性的问题,提出了一种加权系数平均法改进的小波域LMMSE信道估计算法.运用离散小波变换对LS初始估计和预滤波处理后的信号实行阈值量化去噪处理,然后结合时域信道能量分布的稀疏性特征,利用加权系数平均法求出各子载波的频域响应,从而克服了传统LMMSE算法需要预先知晓信道统计特性的缺陷.对算法的BER和MSE性能进行实验仿真,结果表明:文中所提改进算法的信道估计整体性能显然会更优于LS、SVD-LMMSE以及加权平均改进后的LMMSE算法.另外,在信噪比较低且信道统计特性未可知的状况下,文中算法要优于传统的LMMSE算法,并能够较好地降低噪声的影响,有效提升信道估计的精确度.     

高职酒店管理专业建设的探索与实践

目前酒店业发展非常迅速,对从业人员的素质要求也越来越高。为满足酒店业人才需求标准,高职酒店管理专业应加强专业建设,从人才培养模式、课程体系与教学内容、“双师”结构专业教学团队、实践教学等方面进行探索与实践。     

不同萃取剂测定茶叶中氯噻啉残留量的方法比对

采用高效液相色谱法,分别以正己烷、乙腈、丙酮、正己烷-乙腈(体积比1:1)、乙腈-丙酮(体积比1:1)、正己烷-乙酸乙酯(体积比1:1)作为萃取剂,对测定茶叶中氯噻啉残留量的方法进行比对分析。结果表明:6种萃取剂对茶叶中的氯噻啉均有较好的萃取率,并且杂质干扰较少。在萃取体积为20mL时萃取效果最为理想;样品加标平均回收率分别在82.3%~100.7%,85.8%~101.1%,85.9%~95.2%,82.3%~101.3%,82.4%~100.5%,88.6%~102.3%,相对标准偏差均小于10%。其中复合萃取剂的萃取能力较优,而正己烷-乙酸乙酯(体积比=1:1)萃取能力最强,稳定性也较好。     

不同生鲜水牛乳滴定酸度的分析

按GB 4789.18—2010《乳与乳制品检验》标准对云南省主要奶水牛养殖小区、合作社同一季节26户养殖户的228个水牛生乳及相同来源不同月份的655个水牛生乳的酸度进行滴定,同时进行酒精检测和掺碱试验,并对日粮组成、饲喂模式及胎次和泌乳天数进行普查。同一季节不同来源的228个水牛生乳滴定酸度在10~13°T的占83.8%;相同来源不同月份的655个水牛生乳样品的滴定酸度在10~13°T的占86.4%;总的883个生鲜水牛乳滴定酸度为10~13°T的占85.7%,大于14°T占10.6%,小于10°T仅占3.6%。     

基于统一建模语言的虚拟企业信息系统设计方法

分析了虚拟企业项目合作所面临的一些问题及其对信息系统的要求,构造了虚拟企业信息系统的参考框架结构。利用代表面向对象系统分析技术最新进展的一建模语言,对该信息系统进行了信息建模分析。介绍了统一建模语言的特性,结合实例给出了利用统一建模语言建立协作信息模型的实施方法。最后,分析了这一方法在系统实现中的优越性。     

Liquid pressure sensing system based on distributed polarization crosstalk analysis in polarization maintaining fiber

A novel quasi-distributed liquid pressure sensing system based on distributed polarization crosstalk analysis (DPXA) in polarization maintaining fiber (PMF) is proposed and demonstrated. We design a special structure of liquid pressure sensing units and invent a corresponding nonlinear calibration method. Five sensing units deployed on a sensing tape can effectively transform the liquid pressure into the transverse-force applied on the sensing PMF, and the induced polarization crosstalk can be measured and located by the DPXA system, so as to further establish the relationship between liquid pressure and crosstalk through the nonlinear calibration method. The liquid pressure sensing system has good sensitivity and high repeatability, and a maximal measurement relative error of 8.96% is measured for the five sensing units, which can be much improved by optimizing the packaging of sensing units. We believe our sensing system will find great applications in the field of engineering liquid pressure sensing.     

Calculation of the Quasiternary Systems:Si_3N_4-Y_2O_3-SiO_2,Y_2O_3-SiO_2-BeO and Y_2O_3-Al_2O_3-BeO

Based on the thermodynamic model of Kaufman for the calculation of quasibinary and quasiternary system, numerical method for the calculation of stable equilibrium is developed and thermodynamic data of undefined phases are discussed in this work for several ceramic systems.The calculated isothermal sections in Si3N4-Y2O3-SiO2 system meet well with other previous calculated phase diagrams and experimental results. The diagrams in Y2O3-SiO2-BeO and Y2O3-Al2O3-BeO systems are calculated for the approach of prediction.