并网接口滤波器拓扑结构推演与分析

作为并网逆变器的重要组成部分,接口滤波器滤波特性的好坏直接决定着逆变器的并网性能和成本体积。从滤波器拓扑结构入手,在深入分析现有L型、LCL型和LLCL型滤波器特性的基础上提出了一种并网接口滤波器统一电路模型。根据该模型对五阶以下滤波器可能的拓扑结构进行推演、归纳与比较,提出了LLCCL1型和LLCCL2型两种新型滤波器拓扑结构。在逆变器侧高频谐波衰减特性、电网侧高频谐波抑制特性、参数设计及谐振尖峰无源阻尼等方面对新型滤波器和现有滤波器进行了详细地对比研究。理论分析和仿真结果均验证了所提出拓扑结构推演方法和新型滤波器结构的正确性和合理性。     

有源电极表面肌电信号在检测中的应用

目的：准确地检测表面肌电信号。方法：研究减小表面肌电信号检测中的噪声方法，探讨如何采用差分结构放大器、有源电极、滤波器等方法设计电极单元，以及电极形状和正确的放置方法。结果：采用仪用放大器AD620设计了双极性的有源电极成功用于表面肌电信号检测。结论：实验表明，采用有源电极可以提高信噪比，减小噪声，有效地提取出表面肌电信号。     

新型混合滤波器在FDK算法中的应用

目的 探讨新型混合滤波器在锥束CT图像重建FDK算法中的应用价值。方法 对使用锥束CT图像质量检测模体CatPhan 500获得的投影数据进行FDK算法重建,重建过程中分别应用由R-L滤波器和S-L滤波器组成的传统混合滤波器及R-L滤波器和NEW滤波器组成的新型混合滤波器,比较两种混合滤波器重建图像的质量。结果 与传统混合滤波器相比,新型混合滤波器重建图像的对比噪声比及空间均匀性有所提高,且图像噪声有所降低;而两种混合滤波器重建图像的空间分辨率无明显差别。结论 FDK算法中新型混合滤波器在重建图像空间分辨率无明显下降的情况下,提高了对比噪声比及空间均匀性,降低了图像噪声,因此新型混合滤波器的重建效果优于传统混合滤波器。     

一种高动态性能的级联型有源电力滤波器

基于级联H桥多电平拓扑的有源电力滤波器(Active Power Filter, APF)的研究越来越广泛。本文针对级联型APF系统的动态性能进行了研究。首先分析了电网电流反馈控制动态响应慢的原因和理想情况时的动态响应,在此基础上提出了一种提高系统动态性能的方法,该方法的特点是:稳态时,系统的控制策略为电网电流反馈控制,负载突变时,系统采用复合控制策略。文中进一步详细阐述了其实现方法,并对级联APF直流侧电容电压均衡控制的原理及其硬件实现进行了描述。仿真和实验结果表明,采用该方法的级联APF具有较高的稳态和动态补偿性能。     

有源电极表面肌电信号在检测中的应用

目的:准确地检测表面肌电信号。方法:研究减小表面肌电信号检测中的噪声方法,探讨如何采用差分结构放大器、有源电极、滤波器等方法设计电极单元,以及电极形状和正确的放置方法。结果:采用仪用放大器AD620设计了双极性的有源电极成功用于表面肌电信号检测。结论:实验表明,采用有源电极可以提高信噪比,减小噪声,有效地提取出表面肌电信号。     

强化降糖降压治疗2型糖尿病微血管病变的前瞻性研究

目的为了解强化降糖、降压治疗对2型糖尿病微血管病变的影响。方法2001年7月～2005年2月对84例2型糖尿病患者进行随机、开放、对照、研究,共分成强化降糖、降压组(A组)、强化降糖组(B组)、强化降压组(C组)、一般降糖降压组(D组)。主要观察其尿微量白蛋白及视网膜病变情况。结果(1)强化降糖降压组,尿微量白蛋白/肌酐值明显降低(P<0.01),眼部病变发生亦明显减少(P<0.01)。(2)单纯强化降糖、强化降压组与一般降糖降压组比较,其微血管病变亦明显降低(P<0.05)。(3)单纯强化降糖与强化降压组间比较,其微血管病变降低(P<0.05)。结论强化降糖、降压治疗,对于预防2型糖尿病微血管病变有重要意义,但是在单纯降糖和降压方面,强化降糖治疗对于预防微血管病变优于单纯强化降压。     

高电位工作电压源换流器供电电源设计

介绍了电压源变流器(VSC)在输配电领域应用的几种拓扑,指出工作在高电位的VSC控制单元可靠供电是核心技术之一。在此基础上分析了高电位VSC供电需求,通过对几种常用的直流转直流(DC-DC)拓扑进行了比较,指出双管反激拓扑更适合于高电位VSC供电。最后设计了基于双管反激的DC-DC变换器。仿真和试验结果吻合较好,并将其应用于配电静止无功补偿器(D_STATCOM)。     

山绿茶降压片治疗原发性高血压101例临床观察

为观察中族山绿茶降压片的降压疗效、量效关系及不良反应，采用中族山绿茶降压片治疗原发性高血压49例，并与络活喜治疗52例相比较。结果：2组有效率相比无显著差异(P＞0.05)。结论：对轻中度原发性高血压中族山绿茶降压片在降压有效率和降压效果方面与西药络活喜无显著性差异，证明山绿茶降压片是一种有效、安全的纯中药降压药，无明显的不良反应，而且无明显的剂量与效应关系。     

有降压作用的非传统降压药物研究现状及意义

随着对高血压发病机制、病理生理研究的不断深入,高血压的治疗也更科学和全面.但在高血压治疗领域仍面临传统降压药物尚未解决的问题,如高血压患者收缩压(SBP)、脉压(PP)控制相对较差、如何改善动脉壁弹性以及胰岛素抵抗(IR)等,在新型降压药物研发与问世的同时,发现了许多非传统降压药有降压作用.为了扩展降压治疗的策略、丰富降压治疗的手段,现就目前有降压作用的非传统降压药的研究现状、可能机制、临床意义等作一综述.     

身心放松疗法在A型行为原发性高血压患者中的应用

目的:探讨身心放松疗法在A型行为原发性高血压患者中的应用价值。方法:将96例A型行为原发性高血压患者采用自身对照法,干预前给予常规药物治疗及护理,干预后在干预前基础上加用身心放松疗法。干预前后分别测量患者的血压,比较其降压效果,并采用A型行为类型评定量表(TABPQ)评定其行为。结果:干预后降压显效率、有效率均高于干预前(P0.01),TABPQ各因子分值均明显低于干预前组(P0.01)。结论:身心放松疗法可明显改变A型行为原发性高血压患者的性格行为,有利于提高降压效果。     

数字滤波对脑电功率谱影响的研究

采用二阶、四阶、八阶递归数字滤波软件，使用不同的滤波参数，对２．０－２０．０Ｈｚ的１００条脑电曲线进行试验研究。结果为：各阶滤波均功率谱曲线的幅值有明显影响；四阶以上显示显著性差异；各阶波滤对δ频带的频率有明显影响；滤波阶次越高，则其影响越大；同一频带改变量百分比的标准差较大，即离散度大，尚无法校正；数字滤波技术在脑电地形图诊断中应用尚存在明显缺陷。提出了使用数字滤波时的弥补措施。     

Safety of Implantation of a Leadless Pacemaker via Femoral Approach in the Presence of an Inferior Vena Cava Filter

A 61‐year‐old woman with symptomatic complete heart block was referred for permanent pacemaker. The presence of a left‐sided arteriovenous fistula and right‐sided mastectomy with lymph node dissection precluded the implantation of a transvenous pacemaker, and therefore, a leadless pacemaker was recommended. The patient also had an inferior vena cava (IVC) filter. The passage of a 27‐French introducer sheath housing the leadless pacemaker through IVC filter was carefully visualized under fluoroscopy and advanced to the right ventricle without any compromise to the filter. This case report shows the safety of passage of large sheaths via the IVC filter.     

Localization bias and spatial resolution of adaptive and non-adaptive spatial filters for MEG source reconstruction

This paper discusses the location bias and the spatial resolution in the reconstruction of a single dipole source by various spatial filtering techniques used for neuromagnetic imaging. We first analyze the location bias for several representative adaptive and non-adaptive spatial filters using their resolution kernels. This analysis theoretically validates previously reported empirical findings that standardized low-resolution electromagnetic tomography (sLORETA) has no location bias. We also find that the minimum-variance spatial filter does exhibit bias in the reconstructed location of a single source, but that this bias is eliminated by using the normalized lead field. We then focus on the comparison of sLORETA and the lead-field normalized minimum-variance spatial filter, and analyze the effect of noise on source location bias. We find that the signal-to-noise ratio (SNR) in the measurements determines whether the sLORETA reconstruction has source location bias, while the lead-field normalized minimum-variance spatial filter has no location bias even in the presence of noise. Finally, we compare the spatial resolution for sLORETA and the minimum-variance filter, and show that the minimum-variance filter attains much higher resolution than sLORETA does. The results of these analyses are validated by numerical experiments as well as by reconstructions based on two sets of evoked magnetic responses.     

Failure of the intracaval filter of Günther to prevent recurrence of pulmonary embolism — report of two cases

Two out of nine patients in which inferior vena cava interruption was performed with a Günther filter developed a recurrent pulmonary embolism. In both cases, the filter had moved down and the anchoring legs had perforated the wall of the vena cava. The source of the pulmonary embolism was a clotted basket filter. Anticoagulation was given for two weeks in one patient and six months in the other after insertion of the filter, but it had been stopped before the thrombotic event leading to the recurrent pulmonary embolism. The formation of the thrombi had probably been caused by the migration of the filter and the subsequent perforation, which may have been facilitated by the cessation of the anticoagulation.     

手术室空调滤尘网带菌状况分析及对策

目的了解手术室空调滤尘网带菌状况,以便采取相应措施控制院内感染.方法检测手术室紫外线消毒前后的空气菌落数和空调滤尘网表面菌落数;滤尘网用500 mg/L含氯消毒剂浸泡消毒,并于消毒后即时、1周、2周、3周、1月采样进行细菌培养.结果紫外线消毒前后,手术室空气菌落数的差异有统计学意义,空调滤尘网表面菌落数的差异无统计学意义.滤尘网消毒后即时其表面细菌数符合Ⅱ类环境的要求,消毒后2周内细菌数与消毒后即时的差异无统计学意义,而消毒3周后细菌数与消毒后即时的差异有统计学意义.结论应定期对空调滤尘网进行清洗与消毒,消毒液可选用500 mg/L含氯消毒剂,清洗消毒间隔时间以2周为宜.     

SRBF: Speckle Reducing Bilateral Filtering

Speckle noise negatively affects medical ultrasound image shape interpretation and boundary detection. Speckle removal filters are widely used to selectively remove speckle noise without destroying important image features to enhance object boundaries. In this article, a fully automatic bilateral filter tailored to ultrasound images is proposed. The edge preservation property is obtained by embedding noise statistics in the filter framework. Consequently, the filter is able to tackle the multiplicative behavior modulating the smoothing strength with respect to local statistics. The in silico experiments clearly showed that the speckle reducing bilateral filter (SRBF) has superior performances to most of the state of the art filtering methods. The filter is tested on 50 in vivo US images and its influence on a segmentation task is quantified. The results using SRBF filtered data sets show a superior performance to using oriented anisotropic diffusion filtered images. This improvement is due to the adaptive support of SRBF and the embedded noise statistics, yielding a more homogeneous smoothing. SRBF results in a fully automatic, fast and flexible algorithm potentially suitable in wide ranges of speckle noise sizes, for different medical applications (IVUS, B-mode, 3-D matrix array US). (E-mail: balocco.simone@gmail.com)     

滤器处理脂血在凝血功能检测中的应用价值

目的 探讨脂血经滤器处理后凝血指标变化情况.方法 选取30例标本,按凝血检测数据（PT、APTT、Fib）分为三组;按照确定的脂血浓度,测定每份标本原始及加入脂肪乳后经过滤标本的凝血指标.结果 过滤后血浆样本的PT、APTT无显著性变化（P＞0.05）,而Fib具有显著性变化（P＜0.05）.结论 0.22μm滤器可有效过滤血浆中的乳糜微粒,并且不影响PT、APTT检测的准确性,为实验室提供了一种因输注脂肪乳而造成的脂血标本的有效检测方法.