非相干硬判决多进制直扩系统的门限选取

首先介绍一种采用非相干硬判决的多进制直扩通信系统的构成和原理，然后推导出一套在高斯白噪背景和窄带干扰下系统的纠错前符号差错率估算公式，并研究最佳门限问题。最后给出一些数值结果并简单总结全文。     

无扩频矩阵知识二维扩频系统的盲同步

针对加性白高斯噪声信道,考虑未知二维扩频矩阵的条件下,提出了一种二维扩频系统的时频同步方法。该方法利用二维扩频矩阵周期性重复的特点,先估计出频率偏差,再通过滑动暂存窗求相关矩阵最大特征值,完成信号的时间同步。计算机仿真结果验证了该方法的有效性。     

阴极发射电流对磁控管性能的影响

利用三维粒子模拟软件,比较研究了在磁控管模拟计算中三种阴极发射方式在电流控制、宏粒子数和计算度上的不同,确定了Beam发射是电流控制的最好发射模式;在固定电子能量的基础上,研究阴极电流发射密度分别为9A/cm 3A/cm~2和7A/cm~2下的输出频谱和模式竞争过程,研究结果表明:选择合适的发射电流大小有利于磁控管频谱噪声抑制．     

Which Neuropsychiatric Disorder Is More Associated With Divorce?

The social disruption experienced by people with neuropsychiatric disorders may be pervasive and manifest in divorce. It has been estimated that 90% of marriages involving a partner with bipolar disorder culminate in divorce. To verify this information we studied the results of the 2004 National Nursing Home Survey. We found that the percentage of divorced residents was 7%. However, “lonesome” status (widowed, divorced, separated, never married, and single) was prevailing in 79% of residents. The rates of divorce were highest among bipolar, paranoid, and schizophrenic residents (18%, 12%, and 12%, respectively). Lonesome status was also highest among bipolar, paranoid, and schizophrenic residents (85%, 84%, and 83%, respectively). Never married status was highest among those with schizophrenia, obsessive-compulsive residents, and bipolar patients (12%, 12%, and 11%, respectively). We conclude that shizophrenic and bipolar patients are very likely to never get married or to end up divorced.     

Companion animals in families of children with autism spectrum disorder: Lessons learned from caregivers.

Companion animals (i.e., pets) have been increasingly recognized for the roles they play in families, including those with children with Autism Spectrum Disorder (ASD). This cross-sectional study explored the unique functions of companion animals within families with a child with ASD. Phenomenology was used to analyze the responses of participants (N = 338) who responded to a survey offered through the Interactive Autism Network. The study initially focused on dogs; however, the analysis was forced to expand to other species due to the data provided by participants. Seven major themes emerged: bonding and benefits, learning opportunities, barriers, grief, fit (match of family characteristics with those of the companion animal), safety, and alternative animals. Successful fit between companion animals and families was often described as necessary for beneficial functions. Barriers included necessary cost and time, as well as required supervision of interactions to enhance safety of the children and animals.     

作为人类共同继承财产的频谱和轨道资源

无线电频谱和卫星轨道资源是有限的自然资源, 在国际层面通过国际电信联盟的国际合作管理机制在成员国间进行分配, 其依据是世界无线电通信大会上各国共同制定的《无线电规则》。各国对无线电频谱和卫星轨道资源的权利是具有一定优先权的使用权, 这类资源具有国家不得对其主张主权或据为己有、通过国际合作共同管理、各国人民公平地分享资源、为和平目的使用的特征, 是人类共同继承财产。空间商业化趋势带来的卫星及其所用频率和轨道位置跨国转让的问题, 呼吁资源分配的国际机制的改革, 以实现资源利用效率最大化和各国资源需求的平衡。     

基于投入产出系数矩阵的周期增长模型

在Goodwin和Brody周期增长理论的基础上,本文构造了基于投入产出系数矩阵的开放经济非线性经济周期增长模型,并在简化情况下,利用42部门投入产出表的基础数据,对中国经济增长的周期谱进行了分析。结果表明,模型对中国经济周期的结论是适当的和稳健的。在短周期谱中,中国经济1978年以来主要表现出6年左右的周期,且数据表明,主要周期向10年左右加长。     

Different estimators of the spectral matrix: an empirical comparison testing a new shrinkage estimator

ABSTRACT

In this paper we propose a new non parametric estimator of the spectral matrix of a multivariate stationary stochastic process, with the main goal to locally improve the deficiencies of the smoothed periodogram in terms of mean square error of the estimates. Our estimator is based on a convex linear combination of the frequency averaged periodogram and an estimate of the true mean spectral matrix across frequencies. In a wide simulation study we show that our estimator turns out to be able to markedly improve the frequency averaged periodogram especially at central frequencies.     

利用紧束缚近似法计算无边界石墨烯的电子能级

石墨烯是近年发现的二维碳原子晶体,它是目前凝聚态物理领域的研究热点之一．石墨烯是构筑各种碳质材料的基本结构单元,具有很多奇特的物理性质．本文简要介绍了石墨烯的发现历史和分子结构,并着重利用紧束缚近似法计算了无边界石墨烯的能谱结构．通过对其结果的分析,在理论上解释了石墨烯呈现金属性的原因．     

低信噪比下非周期性直扩信号的盲估计

为解决低信噪比下非周期性直扩信号PN码序列的盲估计难题,提出了以两倍信息码元宽度为分段长度的分段矩阵特征分解法(SEVD)对PN码序列进行初步估计,然后对得到的各段估计序列进行拼接,再通过基于最优移位相加特性的信息码剥离算法得到原始PN码序列的盲估计方法,该方法采用并行处理以提高运算速度,并具有无需事先提取同步信息、能够消除"反码"现象的优点。仿真结果表明该方法能够在信噪比大于?17dB条件下对扩频码码长为1023的m序列的非周期性直扩信号做到无误码盲估计。