二氧化硅负载五氧化二钒合成、表征和催化性能研究

在以丙酮为溶剂、以V2O5/SiO2为催化剂、8-羟基喹啉为助剂的催化条件下,以过氧化氢水溶液为氧化剂,对环己烯催化氧化制备环己烯酮的催化反应体系进行了研究。考察了V2O5的负载量以及8-羟基喹啉的用量及反应温度对环己烯氧化反应的影响,发现适当的负载量有利于V2O5催化性能的提高。结果表明,当V2O5负载量(质量分数)为5%、催化剂的量和8-羟基喹啉的质量相等、反应温度为30℃时环己烯的转化率和环己烯酮的选择性较好。这源于V2O5高度分散于SiO2载体上,增大了活性组分V2O5的表面积,从而增加了其活性中心的个数及活性组分与反应物的接触面积,从而增加了催化活性。     

全数字突发模式8PSK系统的时钟和载波同步

突发模式传送系统中前导字作为系统开销降低了数据传送效率,提出一种全数字无前导字突发模式8PSK接收机方案,接收机的时钟和载波恢复均采用前向同步技术,并对载波频偏恢复算法进行了详细推导,并通过仿真验证了算法的可行性和有效性。     

Harmonic mixing of Bi2Sr2CaCu2O8+x intrinsic junction at millimeter waveband

Using intrinsic Josephson junctions in Ba₂Sr₂CaCu₂O_8+x single crystal, harmonic frequency mixing at 8 and 3 mm wavebands was successfully demonstrated at liquid nitrogen temperatures with harmonic numbers up to 68 and 50 respectively. The dependences of intermediate frequency output on the local oscillator power and dc bias were carefully studied.     

Moving object detection in framework of compressive sampling

Compressive sensing is a revolutionary idea proposed recently to achieve much lower sampling rate for signals. In the image application with limited resources the camera data can be stored and processed in compressed form. An algorithm for moving object and region detection in video using a compressive sampling is developed. The algorithm estimates motion information of the moving object and regions in the video from the compressive measurements of the current image and background scene. The algorithm does not perform inverse compressive operation to obtain the actual pixels of the current image nor the estimated background. This leads to a computationally efficient method and a system compared with the existing motion estimation methods. The experimental results show that the sampling rate can reduce to 25% without sacrificing performance.     

鄂尔多斯盆地南缘长8储层岩石力学特征及影响因素

鄂尔多斯盆地南缘中生界长8是进行油气开发的重点层位,针对长8储层砂泥岩交互,低孔低渗的特点,对其岩心样品开展了模拟地层下的岩石力学实验研究。实验研究表明：三轴条件下,岩心样品均随着围压的增大,破坏强度变大,即弹性极限显著增加;随着围压的增大,岩石的抗压强度显著增加;随着围压的增大,岩石的变形显著增大。利用测井资料,计算出了动态岩石力学参数并结合实验结果进行了动静态参数拟合,结果表明在进行GR加权的情况下拟合情况较好,因此构建了较可靠的岩石力学参数剖面。在岩石力学参数剖面的基础上,对岩石力学参数空间分布的影响因素进行分析,表明影响泊松比、杨氏模量和抗压强度空间分布的主要因素为岩性、泥质含量和深度。研究成果对鄂南地区长8储层的压裂优化设计提供了重要的依据。     

Novel matched filtering method and its application

The method of using a narrowband filter to realize matched filtering is derived. A novel method of using spectrum sampling to realize matched filtering is presented, and the method can conquer the disadvantages that the narrowband filter cannot adopt the adaptive scheduling of phased array radars and realize matched filtering for several waveforms. A novel error extraction method is proposed, which uses a time division multipath method to realize the intermediate frequency extraction. This method can save lots of space for vehicle-born radar systems, reduce the influence of amplitude and phase distortion caused by devices, and enhance the system reliability. Simulation results show that the spectrum sampling method is applicable, and the implementation of frequency spectrum sampling is elaborated.     

拟正则图的最大线图连通度及其应用

引入了则（ｐ，ｑ）图的最大线图连通度Ｒ（ｐ，ｑ），得到上、下界至多相差１的Ｒ（ｐ，ｑ）的取值范围：２ｍ－２≤Ｒ（ｐ，ｑ）≤２ｍ－２＋［２ｍｒ＋ｒ／ｍｐ＋ｒ］，其中ｍ＝［２ｑ／ｐ］，ｒ＝（２ｑ）ｍｏｄｐ。将此结果应用于容错多总线系统的最优设计，提出了两类最优容错设计，推广了已有结果，并揭示出处理机个数相对于总线条数较大时最优容错设计的广泛存在性。     

基于LQG控制的整车8-DOF系统振动分析

建立了整车8-DOF系统动力学模型,考虑了主动悬架控制,并增设了主动座椅控制,设计了车辆主动悬架系统的LQG控制器。基于Matlab仿真平台建立了整车8-DOF系统动力学仿真模型,对所得最优控制策略下的动态响应进行了仿真验证。仿真结果表明:为了改善人椅系统质心及车身质心的跳振性能需要在一定程度上弱化各轮轮胎动位移性能。从控制效能上来看,该最优控制器能够满足各行驶状态下对悬架性能的要求,改善了车辆的行驶平顺性。     

基于Multisim8的8路抢答器的设计与仿真

基于Multisim8设计8路抢答器电路,并对其进行了仿真,结果完全达到了预期的要求。电路设计主要分为3大部分:控制电路部分、编码显示部分、报警封锁部分等。控制电路主要功能是将首位选手抢答成功的信号传送给编码显示电路以及报警封锁电路;编码显示电路的功能主要是将抢答成功的信号转换成4位二进制的码,然后用4位输入的数码管显示十进制的选手的编号,并且该选手前的指示灯被点亮;报警封锁电路的主要功能是当有选手抢答成功后将其余选手的信号封锁,同时发出声音提示抢答成功。     

退火温度对Fe_(73.5)Co_(0.3)Cu_1Nb_3Si_(14.2)B_8合金带材磁性能的影响

用单辊法制备的宽为20 mm,厚为25μm的Fe_(73.5)Co_(0.3)Cu_1Nb_3Si_(14.2)B_8合金带材,绕制成外径为40 mm,内径为25 mm的环型磁芯,再将磁芯进行退火处理。分析了合金带材的晶化行为,研究了退火温度对合金磁芯磁性能的影响。结果表明,淬火态Fe_(73.5)Co_(0.3)Cu_1Nb_3Si_(14.2)B_8合金带材为非晶态,一级起始晶化温度T_(x1)为512.8℃,二级起始晶化温度T_(x2)为671.9℃,当退火温度升高到550℃,在非晶基体中析出Fe(Si)软磁相,形成了非晶和纳米晶双相共存结构。当退火温度低于550℃时,随着退火温度的升高,合金磁芯的初始磁导率μ_i和饱和磁感应强度Bs增大,矫顽力Hc减小;当测试频率f和最大磁感应强度Bm不变时,合金磁芯的有效幅值磁导率μ_a增大,比总损耗Ps和交流矫顽力Hc减小;当测试频率f不变时,合金磁芯的电感Ls和品质因数Q增大。