Preventive ablation strategies in a biophysical model of atrial fibrillation based on realistic anatomical data.

Ablation strategies to prevent episodes of paroxysmal atrial fibrillation (AF) have been subject to many clinical studies. The issues mainly concern pattern and transmurality of the lesions. This paper investigates ten different ablation strategies on a multilayered 3-D anatomical model of the atria with respect to 23 different setups of AF initiation in a biophysical computer model. There were 495 simulations carried out showing that circumferential lesions around the pulmonary veins (PVs) yield the highest success rate if at least two additional linear lesions are carried out. The findings compare with clinical studies as well as with other computer simulations. The anatomy and the setup of ectopic beats play an important role in the initiation and maintenance of AF as well as the resulting therapy. The computer model presented in this paper is a suitable tool to investigate different ablation strategies. By including individual patient anatomy and electrophysiological measurement, the model could be parameterized to yield an effective tool for future investigation of tailored ablation strategies and their effects on atrial fibrillation.     

一种基于支持向量机的心电信号处理算法

新一代心电图(Electrocardiography,ECG)系统中,可以使用可穿戴设备来监测人体生理信号.心电图信号是一种生物医学信号,基本上与人体心脏的电活动相对应,根据其波形可以初步判断人体是否存在疾病.本文首先对ECG信号进行了预处理,然后使用自适应阈值对QRS波进行定位,最后使用支持向量机对心电信号进行分类....     

An input-domain based method to estimate software reliability

A method is presented for software reliability estimation that is input-domain based. It was developed to overcome some of the difficulties in using existing reliability models in critical applications. The method classifies the faults that could be in a software program. Then it accounts for the distribution over the input-domain of input values which could activate each fault-type. The method assumes that these distributions change, by reducing their extent, with the number of test cases correctly executed. Using a simple example, the paper suggests a convenient fault classification and a choice of distributions for each fault-type. The introduction of the distributions permit better use of the information collected during the testing phase     

An estimate of the variation of a band-limited process

Upper and lower bounds are established for the mean-square variation of a stationary processX(t)whose power spectrum is bounded byomega_{c}, in terms of its average powerP_{0}and the average powerP_{1}of its derivative. It is shown thatleft( frac{2}{pi} right)^{2} P_{1} tau^{2} leq E {|X(t+tau )-X(t)|^{2}} leq P_{1} tau^{2} leq omega_{c}^{2}P_{0}tau^{2}where the upper bounds are valid for anytauand the lower bound fortau < pi / omega_{c}. These estimates are applied to the mean-square variation of the envelope of a quasi-monochromatic process.     

An active queue management scheme based on a capture-recapture model

One of the challenges in the design of switches/routers is the efficient and fair use of the shared bottleneck bandwidth among different Internet flows. In particular, various active queue management (AQM) schemes have been developed to regulate transmission control protocol traffic in response to router congestion. In addition, in order to provide fair bandwidth sharing, these AQM must protect the well-behaved flows from the misbehaving flows. However, most of the existing AQM schemes cannot provide accurate fair bandwidth sharing while being scalable. The key to the scalability and fairness of the AQM schemes is the accurate estimation of certain network resources without keeping too much state information. We propose a novel technique to estimate two network resource parameters: the number of flows in the buffer and the data source rate of a flow by using a capture-recapture (CR) model. The CR model depends on simply the random capturing/recapturing of the incoming packets, and as a result, it provides a good approximation tool with low time/space complexity. These network resource parameters are then used to provide fair bandwidth sharing among the Internet flows. Our experiments and analysis will demonstrate that this new technique outperforms the existing mechanisms and closely approximates the "ideal" case, where full state information is needed.     

无线体域网中ECG信号Hermite拟合的一种优化算法

心电信号的传输是无线体域网技术中的一个关键技术.提出了一种在无线体域网环境中对ECG信号进行Hermite拟合的优化算法.该方法利用Hermite函数拟合出心电信号,得到拟合参数,并在对信道特征进行估计后将定点化的参数传输.实验结果表明该方法可以很好地拟和出ECG信号的波形,降低压缩比并达到一定的拟和效果,提高ECG信号的检测能力和传输能力.     

基于PACS的心电信息系统

介绍了基于PACS的心电信息系统。该系统使得心电图影像数据在存储可靠性、安全性、通用性等方面得以提升。通过分析现代数字化医院度区域医疗卫生服务平台对心电影像的需求．阐述基于PACS的心电信息系统能为现代数字化医院提供更好的支持。基于PACS的心电信息系统,是一个在设计、开发、应用、维护等各方面性价比突出的方案,可为医疗机构、患者提供有力的支持与保障。     

基于DICOM的心电工作站集成的实现研究

随着医疗数字化的不断深入,传统的、独立于HIS系统、PACS系统之外的心电信息系统已不能满足现化数字化医院的需求。通过解析DICOM3.0标准关于心电和通讯的描述部分,借助工具包DCMTK生成符合DICOM标准的DICOM-ECG文件;并在心电工作站上实现DICOM MWL、DICOM ECHO、DICOM STORE服务来建立与PACS系统之间的通讯,实现心电工作站与PACS系统无缝集成。基于DICOM的心电工作站,是一个在心电数字化的采集、存储、管理等方面比较突出的方案,可为医疗机构和患者提供有力支持和保障。     

Polarization-mode dispersion measurements based on transmissionspectra through a polarizer

Routine characterization of polarization-mode dispersion (PMD) in single-mode fiber, both at the manufacturing stage and in installed systems, requires an easy-to-implement measurement technique. One method that is particularly simple to implement involves counting the number of extrema (i.e., maxima and minima) per unit wavelength interval in the transmission spectrum measured through a polarizer (analyzer) placed at the output of a test fiber. In this paper, we establish accurate equations relating both the extrema density and mean-level crossing densities in such spectra to the expected value of PMD. These equations are used to measure several fiber samples, and are compared to measured values obtained with a commercially available test set. It is shown that measuring both mean-level crossings and extrema densities provides a simple means for establishing whether a fiber is scaling as √L (long-length regime) or L (short-length regime). Using Monte Carlo simulations, the accuracy of the fixed-analyzer measurements is examined as a function of the width of the wavelength interval over which measurements are made. In addition, the simulations indicate that fixed-analyzer measurements are quite robust with respect to the presence of polarization-dependent loss (PDL) in the span, an important consideration for measurements in amplified systems     

An analytic model to estimate the avalanche breakdown voltage improvement for LDD devices

An analytic model is presented to estimate the avalanche breakdown voltage improvement for various lightly doped source-drain (LDD) structures. In this model, the voltage drop across the lightly doped drain region is assumed to be responsible for breakdown voltage improvement. The voltage drop is calculated by assuming a two-dimensional potential distribution in the rectangular section of the n^? region. This section is treated as a volume obeying Gauss' law, thereby enabling the mobile and immobile charges contained in it to be related to the electric fields normal to its surface without considering the detailed distribution of the charges inside. The calculated results agree well with experimental and two-dimensional simulation data for a wide range of processing parameters.     

An inspection model with generally distributed restoration and repair times

In classical inspection models, it is assumed that the inspection time and the restoration time are either zero or fixed, and the production facility never breaks down. However, in real production, the production system is subject to random failures and the repair and restoration times are usually random. In this paper, we will study the effect of the exponential failure time and generally distributed restoration and repair time on the optimal inspection interval of a production unit subject to deterioration. Treating the process as a semi-regenerative process (SRP) and analyzing the SRP by Markov renewal theory, the formula for the long-run expected average cost per unit time and formulae for the steady-state probabilities of the SRP are obtained in an explicit form. The optimal inspection interval is obtained by minimizing the average cost function.     

基于模型调整的自适应交互多模型算法

针对交互多模型算法的技术特点,利用量测中所包含的当前信息对目标模型集的自适应调整并对调整后的模型概率进行估计,实现了模型集的自适应交互多模型算法。介绍了这种算法的设计步骤和仿真方法。仿真结果表明了该算法比标准IMM算法具有更高精度的跟踪性能。     

基于单片机的无线便携式心电传感器

心脏病是一种严重威胁人类生命健康的疾病,文中设计实现了无线心电检测与传输。在采集端,微弱心电信号经放大滤波后,通过ADC转化为数字信号,再由微控制器做进一步的数字处理与分析,最后通过无线模块和串口将数据发送出去。在接收端,通过无线模块获取到无线数据,再由串口将获取的数据发送到上位机以显示。该系统运行稳定、安全可靠,同时具有功耗低、操作简单、便于随身携带等特点,对心血管疾病的实时监测具有重要的意义。     

基于LabVIEW的心电信号插值算法分析

为了在LabVIEW平台下更方便的处理非均匀采样的心电信号,文中研究了心电信号的时域和频域插值算法。首先采用了拉格朗日插值法、牛顿插值法、埃尔米特插值法和三次样条插值法等四种时域插值方法,从算法精度、内存消耗和时间消耗三个方面做比较,得出埃尔米特插值法最为合适。最后又提出一种频域插值法:补零傅里叶频域插值法,来弥补原始心电信号频域分辨率不足的缺点。     

基于计量学的信息安全测量模型探讨

信息安全计量有其特殊性,除了与时间相关的测量以外,其他方面难以应用国际基本测量单位（SI）,缺少对不确定性定量分析的方法。相对而言,硬件部分比较容易测量,因为它有成熟的物理与化学测量科学作支撑,但软件部分却要复杂与困难得多,因为缺乏软件方面的测度。论文尝试将计量科学的原理和方法,应用于信息技术产品或系统的安全测量,提出一种信息安全测量模型,并对安全测量的过程模型和信息模型进行了探讨。     

An adaptive plasma glucose controller based on a nonlinearinsulin/glucose model

The design of plasma glucose controllers traditionally relies on linear approaches. The implementation of an appropriate nonlinear model of the insulin/glucose regulatory system into an adaptive controller should predict the insulin-dependent glucose removal more reliably and hence provide better control over a wide spectrum of insulin signals. A discretized form of the model leads to a two-step procedure. First, the measured plasma glucose levels associated with the erogeneous glucose infusion rates are used in the estimation of the past removal rates which, in turn, can be expressed as a weighted sum of past insulin inputs and previous values of the removal rate. Parameters of the sum are adjusted on-line by a recursive method of estimation which features a prefiltering of data to account for a corrupting coloured process noise. The same equation is in turn used to predict the time course of the insulin-dependent fractional rate of glucose removal. The performance of the controller. Tested in vivo in three pigs, is presented for various intravenous or subcutaneous rapid injections and staircase infusions of insulin. Plasma glucose is maintained at an average level of 99.9±8.7% of the target value (% set point±coefficient of variation). The controller reacts promptly to large and rapid variations in insulin action. Although control improves with the number of glucose measurements, the prediction of glucose removal allows for some flexibility in the monitoring of the plasma glucose. Sampling frequency varied from a 2 min interval during transient periods to 7 min as steady states were reached     

Variable group-delay dispersion equaliser based on a lattice-formprogrammable optical filter

The authors report the first realisation of an integrated-optic variable group-delay dispersion equaliser using a lattice-form programmable optical filter. The equaliser consists of seven tunable couplers and six asymmetrical Mach-Zehnder interferometers cascaded alternately in series. The dispersion can be varied step by step from -923 ps/nm to +653 ps/nm     

基于小波分析的心电信号去噪算法研究

心电信号在临床诊断上有非常重要的作用,但由于容易受到噪声干扰,采集的心电信号中通常包含很强噪声,为了有效去除噪声干扰,该文提出了一种基于自适应阈值的小波模极大值算法来进行信号去噪.关键点是在每个分解尺度上自适应的选取合适的阈值,用来对小波变换系数的模极大值点进行筛选,以去除噪声极值点.该文采用MIT/BIH数据库中的数据对算法进行仿真验证,结果表明该算法有更好的去噪效果,同时心电信号能被很好的保留.     

一种基于正弦模型的音频压缩算法

提出一种适用于无线移动通信的低码率音频压缩算法。该算法基于正弦模型,而且针对极低码率的应用做了修正,提高了重建音频的质量。这些修正包括：自适应变换的分析长度,用于匹配跟踪算法和参数量化的心理声学模型以及频域的无相位音频重建算法。主观测试表明,在0.5bit/抽样的码率要求下,重建信号达到并超过了调幅广播的音频质量。     

一种基于面像素模型的图像缩放算法

提出了一种基于面像素模型的图像缩放算法.这种方法考虑了CCD采集像素的实际情况,将每个像素看成是一个长方形,而不像常用算法中把每个像素看成一个采样点,利用现有的像素值重构出原始CCD感光元件上的光强分布,然后通过积分求取单位面积上的光强得到新的像素值.实验结果表明,该方法比常用的图像缩放算法更好地保持了图像高频分量,具有更高的锐度和对比度.同时,所需资源较少、运算速度快,利于VLSI硬件实现和实时处理.