地震作用下不规则建筑AMTMD控制的动力特性-Ⅰ:平动振动控制

主动多重调谐质量阻尼器(AMTMD)最优参数准则定义为:设置AMTMD不规则建筑的最大平动位移动力放大系数最小值的最小化。AMTMD有效性准则定义为:设置AMTMD不规则建筑最大平动位移动力放大系数最小值的最小化与未设置AMTMD不规则建筑最大平动位移动力放大系数之比。使用定义的准则,研究了不规则建筑标准化偏心系数(NER)和扭转对侧向频率比(TTFR)对AMTMD控制不规则建筑平动位移时的最优参数和有效性的影响。     

DS-CDMA卫星通信系统线性多用户检测算法性能比较

CDMA是新一代移动通信系统的关键技术,现代卫星移动通信也采用CDMA技术。多址干扰(MAI)的存在严重影响了CDMA系统的性能,需要采用多用户检测技术进行抑制。本文分析了卫星移动通信系统的模型,将线性多用户检测算法用于卫星移动通信系统,并对传统检测器、解相关检测器、MMSE检测器等线性检测器进行了性能比较。计算机仿真结果表明采用线性多用户检测技术使卫星移动通信系统的性能得到了明显的改善。     

基于DAMA卫星系统的IP接入设计

TCP协议是面向连接的网络传输协议,当其应用在信道资源按需分配(DAMA)的卫星系统中时,TCP连接开始时所需的卫星链路并不存在,从而会导致TCP连接建立的失败。IP接入控制器配置在IP网络、卫星信道及网络管理设备之间,通过IP过滤、IP欺骗等方法将TCP数据转化为申请信令。解决了TCP业务的传输与卫星信道按需分配的匹配问题。     

基于完全图的多支持度阈值关联规则挖掘算法

提出了基于完全图的最大约束条件下多支持度闻值关联规则挖掘改进算法。该算法利用完全图与频繁项集之间的关系，以完全图结点的度作为判断标准，使得寻找单个候选项集Ck（k≥3）的复杂度降低了。在由候选集得到频繁集的过程中，该算法避免了对事务数据库的扫描，从而减小了系统的I/O开销。因此，该算法减小了存储空间，加快了挖掘速度，提高了算法的效率。     

Energy efficient TDMA-based MAC protocol associated with GAF for wireless sensor networks

The design of media access control (MAC) protocol for wireless sensor networks (WSNs) with the idea of cross layer attracts more and more attention. People can improve the MAC protocol by obtaining certain information regarding the network layer and physical layer. This article synthesizes and optimizes certain cross-layer protocols which have existed. On the basis of the routing, topology information in the network layer, and transmission power information in the physical layer, the time slot assignment algorithm has been improved in the MAC layer. By using geographical adaptive fidelity algorithm (GAF) to divide the grids, controlling of transmission power and scheduling the work/sleep duty cycle for sensor nodes, a new MAC protocol has been proposed to decrease energy consumption and enlarge the lifetime of WSNs. Simulation results show that the MAC protocol functions well.     

对蜂窝系统干扰抵消的概述

未来干扰受限的蜂窝网络将越来越受到人们的青睐，尽管在过去20年里对干扰检测接收机的研究和用多用户技术提高性能，今天的接收机仍只能处理图像背景噪声的干扰。将讨论当前和将来的发展趋势，增加多用户接收机对同时能检测大量异步用户的上行链路及用户被预定和正交化的下行链路的需求和可行性，对最近对干扰抵消的研究突破和为将来多用户接收机集中系统水平考虑作出了总体概述。     

Youth crowds and substance use: The impact of perceived group norm and multiple group identification.

The impact of group identity on adolescent tobacco, alcohol, and marijuana use was examined through a postal survey. The study included adolescents who identified with 1 subgroup (n = 1425) as well as adolescents who identified with 2 (n = 895) or 3 (n = 339) subgroups. The results showed that identification with the pop, skate/hip-hop, techno, and hippie subgroups was associated with higher risks of substance use, whereas identification with the sporty, quiet, computer nerd, and religious subgroups was associated with lower risks. Perceived group norm mediated the group identity-substance use relationship. Furthermore, identification with multiple groups with corresponding norm increased norm-consistent substance use, whereas identification with multiple groups with opposing norms reduced normative behavior. Implications for health promotion are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

MSB-CAATI算法在多波束测深系统中的应用

计算到达角瞬态成像技术(CAATI)是多角测深侧扫声纳(MSBSS)采用的高分辨方位、幅度联合估计技术。本文将CAATI技术扩展到多波束测深声纳(MBBS),提出了一种新的多子阵波束域CAATI(MSB-CAATI)算法。仿真实验证明了该算法与CAATI技术相比具有更高的估计精度和更低的分辨力门限。海试数据的处理验证了MSB-CAATI能很好地应用到多波束测深系统中,使其兼备了FT(傅氏变换)和CAATI各自的优点,能在整个条带宽度内同时获得高分辨力的海底地形和地貌信息,且不易受到低信噪比和复杂地形环境的影响。     

基于高斯粒子滤波的当前统计模型跟踪算法

对于非线性系统估计问题,高斯粒子滤波器可以获得近似最优解,与粒子滤波器相比其优点是不需要重采样步骤和不存在粒子退化现象.采用高斯粒子滤波代替当前模型自适应跟踪算法中的卡尔曼滤波,将高斯粒子滤波与当前统计模型的优点相结合,提出了一种新的当前统计模型自适应跟踪算法,用于非线性非高斯系统的机动目标跟踪.MonteCarlo仿真表明,该算法跟踪精度优于标准的交互多模型算法和当前统计模型自适应跟踪算法,实时性好于交互多模型粒子滤波算法.     

Teaching high school students to use heuristics while reading historical texts.

The purpose of this study was to test the effectiveness of different types of instruction and texts on high schools students' learning of (a) history content and (b) a set of heuristics that historians use to think critically about texts. Participants for the study were 128 male and 118 female students, ages 16 and 17 years, from 2 high schools in the western United States. Eight history classrooms were randomly assigned to 1 of 4 interventions: (a) traditional textbooks and content instruction, (b) traditional textbooks and heuristic instruction, (c) multiple texts and content instruction, or (d) multiple texts and heuristic instruction. The heuristic instruction explicitly taught sourcing, corroboration, and contextualization. Students were administered pretests on their content knowledge and their use of heuristics. After an intervention of 3 weeks, students were readministered the content knowledge and heuristics posttests. A mixed-model analysis of covariance indicated that across all conditions, students who read multiple texts scored higher on history content and used sourcing and corroboration more often than students who read traditional textbook material. Findings highlight the importance of reading multiple texts to deepen content knowledge and facilitate the use of heuristics that historians typically use. (PsycINFO Database Record (c) 2010 APA, all rights reserved)