小波包和功率谱密度分析法在混凝土龄期强度监测中的应用

利用压电智能骨料激发的应力波,对混凝土28 d内目标龄期进行信号监测试验研究,并通过功率谱密度和小波包能量分析法对混凝土龄期内监测信号进行分析.试验结果表明:混凝土目标龄期内,随着时间的逐渐增加,混凝土试件中传感器监测信号的小波包能量和功率谱密度的幅值随时间的变化趋势呈现出非线性增长,6 d和12 d是增长变化的分界点,其幅值分别达到了2.345×104 V2、3.923×104 V2和61.54 pV2/Hz,98.86 pV2/Hz.其试验结果与混凝土试件在实际养护过程中试件强度的变化规律具有很好的一致性.     

基于ARMA模型的网络流量预测

随着计算机网络的迅速发展,目前的网络规模极为庞大和复杂,因此发生各种问题的可能性也越大,同时管理网络的难度也增大,传统的网络管理是在告警之后,解决潜在的问题,即为一种响应式的行为,这时候网络的服务很可能已经受到影响,根据实际采集的非单播包数的观测值序列,建立该流量参数的正常行为,然后平稳化该序列,估计出网络流量的ARMA（2,1）模型,用线性最小均方误差预测方法,对网络流量进行预测,并检测在将来超越阈值的可能性和发生时间,这样,在网络过载发生之前,可以预先采取防范措施,来保证网络的正常服务,这种方法改变了以往的网络管理响应方式,使得网络过载的预警成为可能。     

PSdropout卷积神经网络在危化品巡检车中的应用

危化品仓储环境复杂多变,基于卷积神经网络的视觉巡检车需要快速的训练方法以便适用不同的环境,提高卷积神经网络的训练速度是当前亟待解决的问题。迅速在网络中提取有效的神经元,是提高算法训练速度的关键。传统的算法中,全链接层神经元的去留问题通常采用基于伯努力分布假设的Dropout方法,本文提出一种基于泊松分布的Dropout方法。理论上看,在充分利用神经元历史行为的基础上,基于泊松分布与基于伯努力分布的最大似然函数类似。实验结果表明,在保持正确率的情况下,训练提前收敛,节约了训练时间。     

数据丢失情况下的最小二乘参数辨识算法

现有系统参数辨识方法大多是建立在输入输出数据可以完全测量和完全获取的基础上,而在实际系统中,由于传感器故障或网络传输机构故障,使得数据丢失现象经常发生。研究一类线性系统在输入或输出数据丢失情况下的系统辨识问题,并将数据丢失现象描述为随机伯努利序列,在此基础上提出新的辨识算法来估计数据丢失情况下系统的参数。最后,通过仿真示例验证所提算法对数据丢失的影响。结果表明,所提出的算法相较于递推最小二乘法有更好的收敛性。     

基于小波包融合与矩阵主成分分析的人脸识别

提出一种改进的小波包融合＋2DPCA方法,先对图像进行二层小波包分解,再选取最利于判别分类的4幅高频子图进行融合,将融合子图与低频子图分别进行2DPCA降维和特征提取,最后进行决策级融合,得到识别结果。在Yale和JAFFE标准人脸库上的实验结果表明,该改进方法能有效提高识别率。     

Early withdrawal from mental health treatment: Implications for psychotherapy practice.

[Correction Notice: An erratum for this article was reported in Vol 46(2) of Psychotherapy: Theory, Research, Practice, Training (see record 2009-08897-009). The fourth author’s name was mistakenly left out of the author byline and table of contents. The correct author listing for this article is presented in the erratum.] Despite more than 50 years of research on client attrition from therapy, obstacles to the delivery and success of treatments remain poorly understood, and effective methods to engage and retain clients in therapy are lacking. This article offers a review of the literature on attrition, highlighting the methodological challenges in effectively addressing the complex nature of this problem. Current interventions for reducing attrition are reviewed, and recommendations for implementing these interventions into psychotherapy practice are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

快速分组交换(FPS)节点的性能分析

本文将 B-ISDN 中参加交换的信元(cells)划分为实时与非实时两类.当实时类信元超时时,就应将其从交换节点中去掉以减轻节点负载.这是一种简单的负载控制方法.本文分析了在非平衡负载以及存在时间溢出和空间溢出条件下,采用这种负载控制方法的输出排队、无阻塞快速分组交换(FPS)节点的吞吐量、时延和丢失率特性.     

提升机故障信号特征提取方法研究

研究小波包分析的频带频率特性,指出存在频带能量泄漏问题;揭示小波包分析频带能量泄漏的基本规律,提出频带能量泄漏的识别方法和信号特征提取方法。该方法可以排除频带能量泄漏影响,减少特征向量个数,降低分析复杂度。该方法已应用于矿井提升机故障诊断。     

Early prospective studies of the high school dropout.

A limited number of empirical studies conducted between 1950 and 1970 used longitudinal designs to examine the relations between psychological characteristics of students and subsequent high school dropout. Five prospective studies demonstrated that modest but significant relations existed between completing high school and measures of personality gathered in the seventh, eighth or ninth grades. Stronger relations were found in three early studies that examined the link between sociometric measures gathered in late elementary school and high school graduation 6 or 7 years later. Results clarified some methodological requirements for useful research on school completion and suggested that social and emotional variables explain some of the variance in school dropout that is independent of academic performance. Implications are drawn for effective school dropout research, policies, and practices at the local, state, and national levels. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

A comparative study of digital low dropout regulators

Granular power management in a power-efficient system on a chip (SoC) requires multiple integrated voltage regulators with a small area, process scalability, and low supply voltage. Conventional on-chip analog low-dropout regulators (ALDOs) can hardly meet these requirements, while digital LDOs (DLDOs) are good alternatives. However, the conventional DLDO, with synchronous control, has inherently slow transient response limited by the power-speed trade-off. Meanwhile, it has a poor power supply rejection (PSR), because the fully turned-on power switches in DLDO are vulnerable to power supply ripples. In this comparative study on DLDOs, first, we compare the pros and cons between ALDO and DLDO in general. Then, we summarize the recent DLDO advanced techniques for fast transient response and PSR enhancement. Finally, we discuss the design trends and possible directions of DLDO.