认知无线电网络的干扰信道学习算法

认知无线电网络的信道受到干扰情况下,学习性能不好,导致信道失衡。传统的认知无线电网络的干扰信道学习算法采用多模盲均衡宽带压缩频谱联合特征识别算法,当干扰强度较大时,学习均衡性能不好。提出一种基于线性预编码设计的协作频谱共享的认知无线电网络的干扰信道学习算法。通过协作中继方式在服务PU的同时获得传输机会,并给出了PU/SU联合优化的预编码矩阵进行算法改进,采用Jakes功率谱,组成新的云计算联合服务器接收端和发射端节点定位训练序列,将PU、SU预编码矩阵设计问题分解,采用干扰信道学习算法,得到正交通信信道载波均衡控制方程,实现干扰信道的学习算法改进。仿真结果表明,本文算法能有效提高信道学习性能,抗干扰能力增强,吞吐率比传统方法提高35%,展示较好的网络通信性能。     

网络带宽频间谐振干扰时间-尺度分析

在分组交换网络通信系统中,由于带宽频移键控产生谐振干扰,导致信号传输不稳定,甚至产生误码和丢包。提出一种基于连续小波变换与带宽时延-尺度耦合特性构建的复杂网络带宽频间谐振抗干扰算法。对抗干扰模型进行时间-尺度分析,把干扰信号模型分解成一组带宽双曲调频信号,并分析信号时间平移与尺度伸缩等同效应,有效抑制谐振干扰。仿真验证了算法的有效性,时间-尺度建模分析结果准确,有效抑制了网络带宽频间谐振干扰,大幅降低了复杂分组交换网络通信的误码率,对提高网络安全性能具有积极意义。     

铁路通信网络中抗乘性干扰技术的研究

在城市周围由于高强度多径效应影响,铁路网络信号会受到乘性噪声干扰而造成衰减,传统抗干扰方法容易引起通信信号波动而无法保证铁路通信网络的通信精度。提出了一种基于修正补偿思维的铁路通信网络抗乘性干扰技术,通过引入铁路通信网络信号的波普宽度、后验密度等数据对其进行粒子滤波处理,获取铁路通信信号在传递过程中的衰减程度,并以此作为补偿依据,然后根据乘性噪声与信号接收装置间的距离对载波相位和祖玛波普频率误差进行修正,从而实现了铁路通信网络的增强通信。实验结果表明,提出的方法能够极大提高铁路通信网络通信探测精度,有效地提高乘性噪声信号干扰下铁路网络通信的准确性。     

基于LMS算法的自适应干扰消除

介绍了自适应干扰消除的原理和基于LMS的自适应滤波算法,并分析了干扰抵消的频域块LMS算法,给出了算法的数学推导与模型。在宽带干扰,单音余弦干扰和线性调频干扰的条件下,利用Matlab软件进行了算法性能仿真,结果表明LMS算法可以有效地消除上述三种干扰,提高信号传输的质量。     

图像局部自交干扰排除的渐变优化算法研究

在二维平面图形渐变算法中,但是对于较为复杂的图形,由于传统算法本身存在的不足,图形渐变过程中有时会出现一些局部自交现象,影响图形的渐变效果。为了避免上述缺陷,提出了一种图像局部自交干扰排除的渐变优化算法。利用小波对图像的边沿像素进行变换,提取图像边沿的纹理特征,利用K均值聚类方法,对边沿纹理像素设置分类阀指,消除图像局部自交干扰。实验结果表明,利用本文算法下的图像渐变过程得到了优化,取得了令人满意的效果。     

浅谈雷电电磁干扰的耦合方式

本文重点探讨雷电电磁干扰在入侵过程中形成的各种耦合机理及其造成的危害,简要的介绍提高防雷系统电磁兼容能力、有效防止电磁干扰的措施。     

基于干涉图加权叠加的图像压缩算法

在对图像进行压缩的过程中,容易出现信息丢失的情况,导致传统图像压缩算法由于相关性低的图像也可参与等权计算,使得图像产生偏差及失真,无法有效实现图像压缩,提出一种基于干涉图加权叠加的图像压缩算法,给出高相关点的平均形变相位变化速率,依据误差传播定律,求出全部干涉图叠加后高相关点受到的大气延迟干扰,对每个图像对应的相关系数进行计算,依据模型采集高相关目标点,干涉图被叠加后,给出高相关点大气延迟对线性形变速率的干扰,通过移位操作获取样本的Exp-Golomb级数,完成编码获取数据的非负映射操作,利用上一个样本的Exp-Golomb编码级数对当前样本值级数进行估测,通过计算原始干涉图数据和压缩后的干涉图数据的压缩比与峰值信噪比,对压缩效果进行度量。通过光谱相对均方误差RQE对压缩前后的原始光谱和复原光谱进行度量。仿真实验结果表明,所提方法具有很高的精度。     

大学物理薄膜干涉教学探讨

本文结合大学物理教学实践探讨了薄膜干涉教学的思路与方法,先从理解概念入手,再定量分析薄膜干涉条纹的形成,最后引入光的干涉现象的应用,取得了很好的教学效果。     

激光甲烷传感器及其交叉干扰实验研究

基于激光光谱吸收的原理,研究了激光甲烷传感器的测量原理和系统设计,开展了实验室环境下水汽、一氧化碳和二氧化碳等气体对甲烷测量结果的交叉干扰,给出了实验数据并进行了相关分析。实验证明激光甲烷传感器具有测量准确,稳定性高,抗气体交叉干扰等特性。     

Interference of medical contrast media on laboratory testing

The use of contrast media such as organic iodine molecules and gadolinium contrast agents is commonplace in diagnostic imaging. Although there is widespread perception that side effects and drug interactions may be the leading problems caused by these compounds, various degrees of interference with some laboratory tests have been clearly demonstrated. Overall, the described interference for iodinate contrast media include inappropriate gel barrier formation in blood tubes, the appearance of abnormal peaks in capillary zone electrophoresis of serum proteins, and a positive bias in assessment of cardiac troponin I with one immunoassay. The interference for gadolinium contrast agents include negative bias in calcium assessment with ortho-cresolphthalein colorimetric assays and occasional positive bias using some Arsenazo reagents, negative bias in measurement of angiotensin converting enzyme (ACE) and zinc (colorimetric assay), as well as positive bias in creatinine (Jaffe reaction), total iron binding capacity (TIBC, ferrozine method), magnesium (calmagite reagent) and selenium (mass spectrometry) measurement. Interference has also been reported in assessment of serum indices, pulse oximetry and methaemoglobin in samples of patients receiving Patent Blue V. Under several circumstances the interference was absent from manufacturer-supplied information and limited to certain type of reagents and/or analytes, so that local verification may be advisable to establish whether or not the test in use may be biased. Since the elimination half-life of these compounds is typically lower than 2 h, blood collection after this period may be a safer alternative in patients who have received contrast media for diagnostic purposes.     

机床数控系统抗干扰设计方法的研究

文章讨论了机床数控系统电磁兼容抗干扰设计的方法。通过抑制电源线和信号线上的脉冲干扰,有效地屏蔽了模拟信号和数字信号的干扰途径。此外,采用隔离变压器供电对瞬变脉冲串和雷击浪涌干扰能起到很好的抑制作用。     

改进的同频干扰抑制算法及组网信道优化设计

移动通信WiFi网络与无线传感网络交叉组网时,容易产生同频干扰,影响通信质量和信道传输性能。在交叉组网过程中需要对同频干扰进行有效抑制,提高通信可靠性。传统的交叉组网同频干扰抑制算法采用盲源分离抗干扰算法,在交叉组网被动相干定位时时延较大,通信出现延迟。针对上述问题,提出一种改进的交叉组网同频干扰抑制算法,采用传统的盲源分离技术进行信道同频带内干扰噪声分离,对WiFi信道进行信息编码,采用OQPSK调制方法让整个网络都切换到选定的无干扰信道上,引入干扰避免机制,实现交叉组网信道优化设计。仿真实验表明,采用该算法进行同频干扰抑制和优化组网设计,有能效抑制重度的同频干扰,提高组网节点的吞吐量,保证了通信的可靠性。     

WIMAX设备单音干扰抑制功能实现

单音干扰是WiMAX通信系统中的一种常见干扰,在基带处理前引入单音干扰算法能有效抑制单音干扰,提高系统性能。本文提出了一种基于Notch滤波器的抑制固定单音干扰算法及其FPGA逻辑实现方法。文中首先阐述了设计思想,然后讨论Notch滤波器原理及设计方法,最后给出该算法在FPGA中的实现及滤波效果评估。评估测试结果表明该算法不仅可以有效抑制WiMAX通信系统的单音干扰而且易于FPGA逻辑实现。     

浅析机械维修中过盈零件的装配

在现代的机械生产和维修中,过盈配合零件的拆装比较常见,本文就机械维修过程中常见的过盈配合的零件安装和拆卸问题进行分类探讨。     

网络动态干扰监控的信任感知推荐算法设计

网络用户信任感知推荐的准确性设计是提高用户间的社交网络辅助信息信任度的重要依据。传统的网络用户信任感知推荐算法采用的是基于社交网络服务和用户评分的推荐系统,主观性较大,协同过滤效果不好。提出一种基于网络动态干扰监控的信任感知推荐算法设计新方法,设计自适应神经模糊系统网络动态干扰监测算法,构建基于向量空间模型的信任度评价指标体系结构,通过调整网络拓扑权重向量设置信任度周期响应加权变量自适应函数,有效降低迭代算法的运算成本,避免了自适应神经模糊系统网络动态干扰监测加权权重成固化状态,提高抗干扰性能。实验结果表明,算法能使社交网络感知推荐模型的预测误差减少,推荐可靠性优于传统方法。     

浅析汉族学习者缅语句法习得中的母语干扰

本文从语序类型学和时间顺序原则等角度对汉族学习者在语序上出现的错误进行分析。从句法成分缺失角度探讨了母语造成的干扰。     

政府干涉对大宗货物双渠道低碳运输供应链的协调研究

建立一个两级的北江大宗货物供应链系统(分销商同时拥有水路运输渠道和公路运输渠道且以统一的价格向市场销售产品),分别研究政府改善水路运输服务基础设施策略以及政府对水路进行价格补贴策略对大宗货物供应链的影响。结果表明:两种策略不仅平衡陆水运输量,还能增加供应链成员的利润。且改善基础设施后的运量转移效果比政府补贴的效果明显。从短期来看,政府要实施价格补贴策略会较易取得水路运输平衡的效果;从长远来看,政府要实施政府改善基础设施策略才能深度开发水路运输资源。如此交替实施激励措施,才能有效地实现北江大宗货物低碳绿色运输的目标,促进北江大宗货物供应链行业的发展。     

Association of plasma level of thiobarbituric acid reactive substances with extent of hepatocellular injury in preterm infants with cholestatic jaundice

The present study was designed to determine the association between extent of hepatocellular injury and plasma level of thiobarbituric acid reactive substances (TBARS) in pre term infants with cholestasis. Preterm infants (<35 weeks gestation) admitted to the neonatal intensive care unit were enrolled (with their parents informed consent) in either the ‘cholestasis’ group (if their direct bilirubin was >2 mg/dl) (n=25) or in the control group (n=16). Blood samples for measurement of TBARS, direct bilirubin and transaminases were obtained with-in 24 hours of enrollment. The cholestasis and control groups were comparable with respect to gestational age, birth weight and Apgar score. Serum direct bilirubin, SGOT (EC 2.6.1.1) and SGPT (EC 2.6.1.2) levels were significantly high in the cholestasis group. Plasma levels of TBARS in cholestasis group were correlated with SGOT (F=276.92; P<0.0001) and SGPT (F=355.17; P<0.0001) and differed significantly between cholestatic and control infants. Our findings suggest that oxidative stress in preterm infants with cholestasis is associated with hepatocellular injury.     

Oxidative Stress-Induced Response of Some Endogenous Antioxidants in Schizophrenia

Reactive oxygen species (ROS) formed in various metabolic reactions cause unlimited damage by attacking and oxidizing the macromolecules. An arsenal of antioxidant substances neutralizes these ROS at various sites of their metabolic cascade, and if disequilibrium exists between the pro and antioxidant system, oxidative stress persists. The present study was undertaken in schizophrenia, to highlight the response and role of some endogenous antioxidants viz. reduced glutathione (GSH), bilirubin, total proteins, albumin and uric acid in scavenging the ROS. The effect of severity of disease, age factor, and substance abuse was also studied. In all, 50 schizophrenics and 50 age and sex-matched controls were enrolled in the present study. Fasting blood samples were drawn for estimating malondialdehyde (MDA), GSH, bilirubin, total proteins, albumin and uric acid in both the groups. The results were statistically analyzed by Z-test and correlated using correlation coefficient (r). The study shows reduction in MDA levels and decline in the level of endogenous antioxidants, but within the normal range. Chronic schizophrenics were at a higher risk of oxidative stress and age and substance abuse seems to worsen the situation.     

Role of bilirubin, vitamin C and ceruloplasmin as antioxidants in coronary artery disease [CAD]

A study has been carried out on 250 CAD patients to see how the serum levels of three antioxidants i.e., Vitamin C, Bilirubin and Ceruloplasmin are related to the CAD risk factors and characteristics in these patients. The number of severe category CAD patients declined by 7–18% with increasing serum levels of the three antioxidants and, triple vessel disease declined by 14–20%. A decline of 39% in Myocardial Infarction (MI) occurred with increasing serum Ceruloplasmin. Serum Ceruloplasmin was significantly lower in the MI group compared to the non MI group CAD patients. There was a steady and a significant decline in the mean values of serum levels of cholesterol, Triglyceride, VLDL cholesterol along with BMI with increasing serum level. The study indicates that with increasing serum levels of the three antioxidants studied, the % MI along with % Triple vessel disease and severity of CAD goes down suggesting that the modifiable risk factors have to be suitably modified in order to maintain a reasonably high level of these antioxidants, as the risk factors are inversely related to the serum antioxidant levels.