Comparison of the efficacy of defibrillation with the damped sine and constant-tilt current waveforms in the intact animal

The efficacy of defibrillation using the damped sine and constant-tile (60%) truncated exponential waveforms was determined in each of nine dogs. Two measures of efficacy were used to compare the two waveforms: 1) threshold defibrillation current and 2) percent successful defibrillation. For both measures of efficacy, shock strength was expressed in terms of delivered energy. Mean threshold energy was 0.98 J/kg for the damped sine wave and it was 1.24 J/kg for the truncated exponential waveform. Percent successful defibrillation versus energy/kg curves were constructed for each of the waveforms and were found to be essentially the same. Percent successful defibrillation increased with increasing shock intensity. For 50% success, the energy for the damped sine wave was 1.16 J/kg; for the truncated exponential wave, the corresponding value was 1.15 J/kg. A shock of threshold intensity successfully defibrillated in approximately 50% of the defibrillation attempts, i.e., defibrillation threshold corresponds to about 50% successful defibrillation.     

Sequential pulse defibrillation for implantable defibrillators

A technique is described that reduces defibrillation threshold for automatic implantable defibrillators, permits either reducing the size of the pulse generator or increasing the effectiveness of the pulse generator, and provides an increased safety factor. Defibrillation threshold was compared in 12 anesthetized dogs with mean (+/- SD) body weight of 21.6 +/- 3.4 kg for two defibrillating modalities: 1) single pulse technique with current flowing from electrodes in the right ventricle to electrodes either in the superior vena cava or on the left ventricular epicardium, and 2) sequential pulse technique. The sequential pulse technique tested uses two pulses and three or four electrodes. Current of the first 5-ms pulse flows from the superior vena caval electrode to an electrode in the right ventricle, and after a 1-ms interval, current of the second pulse flows from electrodes on the left ventricular epicardium to the right ventricular electrode. Ventricular defibrillation threshold was reduced by 56% to 6.3 +/- 1.03 joules (mean +/- SEM) (P less than 0.01). Because defibrillation threshold is less for sequential pulse defibrillation than for conventional techniques, sequential pulse defibrillators can be smaller and more effective than previously available devices.     

图像的阈值分割法设计

图像分割阈值法具有实现容易、计算量小、性能稳定等优点,因此这种方法成为图像分割领域中应用最普遍的方法。主要讨论了关于图像的单阈值分割算法的设计与实现,比较了基于迭代法和基于最大类间方差法的单阈值分割算法,设计了阈值最大类间方差的分割算法及实现程序。仿真结果表明所提出的算法有效,分割效果好。     

Improvement of defibrillators for EMS use: a problem in engineering and medicine

Recent improvement in defibrillators has been limited mostly to decreased size and weight of portable units. An overview of the scientific literature indicates that the main limitation to further improvement in defibrillators is the lack of medical and physiologic information. Technology probably exists to change defibrillators if the manufacturers know what changes would be desirable. Clinical studies are needed for determining (a) more accurate quantitation of electrical dose for human use, (b) the relative effectiveness of different waveforms, (c) the toxicity and damage of electrical shocks to the heart, (d) the effects of drugs upon defibrillation threshold, (e) improvement of defibrillation techniques, (f) optimal placement and size of electrodes, and (g) the effects of cardiac disease on defibrillation threshold. Most of the needed studies are not technically difficult to carry out but they will be moderately expensive. In some cases special equipment may be needed or special techniques may have to be developed. The experimental animal studies appropriate as background for these clinical studies have been completed. With limited resources available, it is important to ask the most important questions first in order to develop improved defibrillation techniques and defibrillators.     

基于多判据的多目视觉手势立体姿态检测系统研究

为了精确识别人手姿态用于机器手控制,文中讨论一种基于计算机视觉的手势立体姿态检测的新方法.该方法利用多目视觉之间的配合,有效地解决了检测识别时手部关键节点互相遮档的关键问题.采用了自适应阈值分割、harris角点检测、外极线约束等几种合理、有效的点的匹配算法,对不同摄像机拍摄到的手部关键节点进行排序,这样不仅解决了特征...     

An improved time-delay addition method for MOSA resistive leakage current extraction under applied harmonic voltage

The most monitoring techniques of metal oxide surge arresters are based on harmonics analysis of resistive leakage current. Therefore, the extraction of resistive component from total leakage current is required. Up to now, several methods have been proposed for resistive leakage current extraction such as time-delay addition method. This method is only able to separate accurate resistive component under pure sinusoidal applied voltage. An improved time-delay addition method is proposed in this paper which is able to extract surge arrester resistive component under applied harmonic voltage. To accomplish this purpose, experimental tests have been performed on 20 kV surge arrester and obtained voltage and leakage current signals have been applied to the proposed and previous algorithms for resistive component extraction. In addition to investigate the ability of proposed algorithm, a typical surge arrester has been simulated in ATP-EMTP software and total leakage currents have been applied to both algorithms for resistive leakage current extraction. Results show that the proposed method is able to extract resistive component under applied harmonic voltage more accurate than previous one. Therefore, it is an improvement with respect to previous one that only works for sinusoidal voltage.     

Surface defect detection in tiling Industries using digital image processing methods: Analysis and evaluation

Ceramic and tile industries should indispensably include a grading stage to quantify the quality of products. Actually, human control systems are often used for grading purposes. An automatic grading system is essential to enhance the quality control and marketing of the products. Since there generally exist six different types of defects originating from various stages of tile manufacturing lines with distinct textures and morphologies, many image processing techniques have been proposed for defect detection. In this paper, a survey has been made on the pattern recognition and image processing algorithms which have been used to detect surface defects. Each method appears to be limited for detecting some subgroup of defects. The detection techniques may be divided into three main groups: statistical pattern recognition, feature vector extraction and texture/image classification. The methods such as wavelet transform, filtering, morphology and contourlet transform are more effective for pre-processing tasks. Others including statistical methods, neural networks and model-based algorithms can be applied to extract the surface defects. Although, statistical methods are often appropriate for identification of large defects such as Spots, but techniques such as wavelet processing provide an acceptable response for detection of small defects such as Pinhole. A thorough survey is made in this paper on the existing algorithms in each subgroup. Also, the evaluation parameters are discussed including supervised and unsupervised parameters. Using various performance parameters, different defect detection algorithms are compared and evaluated.     

Defect detection of polycrystalline solar wafers using local binary mean

Polycrystalline solar wafers consist of various crystals and their surfaces have heterogeneous textures. The conventional defect detection methods cannot be applied to their solar wafers. In this paper, we propose a concept of local binary mean and its optimization method for selecting optimal threshold T. The input image is broken down into a set of K patch images. Each patch image is used to calculate its local binary mean. The local binary mean value is used as the discrimination measure for detecting defects. Experimental results show that our proposed method achieves a detection rate of 91~94 %. Compared with related defect detection methods, the proposed method has the advantage of detecting various kinds of low gray-level defects such as micro-cracks, fingerprints, and contaminations simultaneously.     

A Simulation Study of an Object-Oriented Integration Testbed for Process Planning and Production Scheduling

Many studies on integration of process planning and production scheduling have been carried out during the last decade. While various integration approaches and algorithms have been proposed, the implementation of these approaches is still a difficult issue. To achieve successful implementation, it is important to examine and evaluate integration approaches or algorithms beforehand. Based on an object-oriented integration testbed, a simulation study that compares different integration algorithms is presented in this paper. Separated planning method and integrated planning methods are examined. Also, situations of both fixed and variable processing times are simulated, and useful results have been observed. The successful simulation with the object-oriented integration testbed eventually will be extended to include other new planning algorithms for examining their effectiveness and implementation feasibility.     

Review of factors that influence the abundance of ions produced in a tandem mass spectrometer and statistical methods for discovering these factors

Proteomic technologies are important because they link genes, proteins and disease. The identification of proteins and peptides has been revolutionized in the last decade by the use of mass spectrometry. This method is highly sensitive and much faster than the chemical reactions used previously because it can fragment peptides in seconds rather than in hours or days. Proteins are digested with an enzyme, usually trypsin, and the resulting peptides are fragmented in a tandem mass spectrometer (MS/MS). The masses of the fragment ions formed in the MS/MS can be used to identify the sequence of amino acids in the peptides. However, a number of different factors have been found to influence the amount of the various types of fragment ion formed. In this article, we review these factors and their interrelation together with the statistical methods used to discover them. Information on the number of fragment ions formed is at present underused in peptide identification algorithms, and fully utilizing this information could improve current algorithms.     

The influence of the regularization parameter and the first estimate on the performance of Tikhonov regularized non-linear image restoration algorithms

This paper reports studies on the influence of the regularization parameter and the first estimate on the performance of iterative image restoration algorithms. We discuss regularization parameter estimation methods that have been developed for the linear Tikhonov–Miller filter to restore images distorted by additive Gaussian noise. We have performed experiments on synthetic data to show that these methods can be used to determine the regularization parameter of non-linear iterative image restoration algorithms, which we use to restore images contaminated by Poisson noise. We conclude that the generalized cross-validation method is an efficient method to determine a value of the regularization parameter close to the optimal value. We have also derived a method to estimate the regularization parameter of a Tikhonov regularized version of the Richardson–Lucy algorithm.   These iterative image restoration algorithms need a first estimate to start their iteration. An obvious and frequently used choice for the first estimate is the acquired image. However, the restoration algorithm could be sensitive to the noise present in this image, which may hamper the convergence of the algorithm. We have therefore compared various choices of first estimates and tested the convergence of various iterative restoration algorithms. We found that most algorithms converged for most choices, but that smoothed first estimates resulted in a faster convergence.     

A simulated annealing approach to makespan minimization on identical parallel machines

This paper addresses a makespan minimization scheduling problem on identical parallel machines. Several heuristic algorithms have been proposed to tackle the problem. In this paper, a very effective simulated annealing method is proposed to generate the near-optimal solution. Computational results demonstrate that the proposed heuristic is very accurate and that it outperforms the existing methods.     

分布式星敏感器下空间目标同步关联方法

将分布式星敏感器作为空间目标的监视平台,需要将多星敏感器拍摄星图中的空间目标即时关联。星图中的空间目标为没有纹理、颜色等特征的弱小目标,无法利用经典目标关联算法解决。以对极几何约束为关联依据,提出一种分布式星敏感器下空间目标同步关联方法。对极几何约束能够描述多视图的内在射影关系,广泛应用于图像匹配和拼接问题,将其应用于目标关联领域。基于实测数据,进行300组星图的关联实验,统计出空间目标关联概率达90%,验证了算法的可行性,给出了关联门限的合理参考值并分析了造成关联错误的多种原因,基于蒙特卡洛法估算误判最大概率。实验证明本文方法在星敏感器工作中的抖动、测量偏差及少量干扰点的影响下有较理想的关联效果。     

异常载荷剔除中幅值与梯度门限的联合应用

幅值门限法对于大误差及超数量级的异常数据具有良好的识别性,而梯度门限法对于小幅值的奇异点检测能力强。针对这一特点,分析比较了幅值门限法与梯度门限法在剔除异常载荷数据过程中的优劣特性,提出联合应用这两种方式来实现对奇异信号的处理,并以装载机传动系为例给出了异常载荷数据剔除的过程及结果,避免了基于假定样本数据服从某种典型概率分布,利用标准差剔除异常数据的方法存在的固有局限性,可以快速、准确地剔除不同概率分布下的样本异常数据。     

复杂背景成像条件下运动点目标的轨迹提取

为改进空间目标天基实时监视能力,研究了美国在空间中段实验卫星上搭载的对空间目标进行在轨检测与跟踪的信号处理器的工作方案.针对该处理器在目标运动轨迹提取阶段采用的先二元速度滤波再能量累积判决的“筛选-确认”解决方案,提出了两点改进方法:一是在“筛选”阶段增加运动速度约束条件,二是在“确认”阶段增加样本均差约束条件,使其在降低虚警概率的同时提高检测概率,从而普遍适用于复杂背景成像条件下运动点目标轨迹的提取.最后,利用实际获取的云层背景图像数据库仿真生成了包含多运动目标的时序图像序列,并以此作为输入信号源分析比较了原算法与改进算法的性能差异.仿真实验结果表明:改进算法在二元速度滤波后候选条痕减少到原算法的50％以下,处理器运行时钟周期数从8.0×106次降低到7.1×106次;最终检测结果显示,改进算法判决门限的合理取值范围增加到20左右,可以实现对多运动目标的实时检测.     

Sequential pulse defibrillation in man: comparison of thresholds in normal subjects and those with cardiac disease

We compared the parameters describing the defibrillation threshold in patients with normal hearts and in patients with ischemic heart disease, using a special electrode system and sequential pulses of current. Twenty-eight patients consented to the study (mean age: 36.6 +/- 10.1 years; mean mass: 80.7 +/- 13.8 kg). Twenty-one patients underwent surgery for Wolff-Parkinson-White syndrome (relatively normal hearts). Six patients had a history of previous myocardial infarction and aneurysm or coronary artery disease; and one patient had been resuscitated from an episode of sudden death, without evidence of consequent myocardial damage. For 26 patients, defibrillation thresholds were determined intraoperatively by passing sequential pulses through a catheter electrode and epicardial mesh electrode. For 2 patients defibrillation thresholds were determined during electrophysiologic study, after ventricular fibrillation was induced by programmed stimulation, by passing sequential pulses through a catheter and skin-patch electrode. Parameters for sequential pulse defibrillation thresholds between the two groups did not differ appreciably. Total energy for patients with normal hearts averaged 9.9 +/- 6.3 J compared to 8.9 +/- 4.6 J for patients with cardiac disease. No patient with cardiac disease had defibrillation parameters that exceeded the range of the normal patients. These results suggest that the presence of cardiac disease may not significantly alter the parameters necessary for successful defibrillation when using sequential pulses for delivery of energy.     

Response sensitivity analysis of the dynamic milling process based on the numerical integration method

As one of the bases of gradient-based optimization algorithms, sensitivity analysis is usually required to calculate the derivatives of the system response with respect to the machining parameters. The most widely used approaches for sensitivity analysis are based on time-consuming numerical methods, such as finite difference methods. This paper presents a semi-analytical method for calculation of the sensitivity of the stability boundary in milling. After transforming the delay-differential equation with time-periodic coefficients governing the dynamic milling process into the integral form, the Floquet transition matrix is constructed by using the numerical integration method. Then, the analytical expressions of derivatives of the Floquet transition matrix with respect to the machining parameters are obtained. Thereafter, the classical analytical expression of the sensitivity of matrix eigenvalues is employed to calculate the sensitivity of the stability lobe diagram. The two-degree-of-freedom milling example illustrates the accuracy and efficiency of the proposed method. Compared with the existing methods, the unique merit of the proposed method is that it can be used for analytically computing the sensitivity of the stability boundary in milling, without employing any finite difference methods. Therefore, the high accuracy and high efficiency are both achieved. The proposed method can serve as an effective tool for machining parameter optimization and uncertainty analysis in high-speed milling.     

Automatic wheeze detection based on auditory modelling

Automatic wheeze detection has several potential benefits compared with reliance on human auscultation: it is experience independent, an automated historical record can easily be kept, and it allows quantification of wheeze severity. Previous attempts to detect wheezes automatically have had partial success but have not been reliable enough to become widely accepted as a useful tool. In this paper an improved algorithm for automatic wheeze detection based on auditory modelling is developed, called the frequency- and duration-dependent threshold algorithm. The mean frequency and duration of each wheeze component are obtained automatically. The detected wheezes are marked on a spectrogram. In the new algorithm, the concept of a frequency- and duration-dependent threshold for wheeze detection is introduced. Another departure from previous work is that the threshold is based not on global power but on power corresponding to a particular frequency range. The algorithm has been tested on 36 subjects, 11 of whom exhibited characteristics of wheeze. The results show a marked improvement in the accuracy of wheeze detection when compared with previous algorithms.     

Optimization of epicardial electrode size and implant site for reduced sequential pulse defibrillation thresholds

The influence of epicardial electrode surface area and implant site on sequential pulse defibrillation threshold was investigated in four isolated heart preparations. Electrodes with surface areas of 2.5, 5.0, and 10.0 cm2 were each sutured, in random order, to the epicardial surface of the isolated heart at each of four sites: mid-ventral left ventricle (LV); mid-dorsal LV; lateral-apical LV; and lateral-basal LV. The epicardial electrode is one of the electrodes in a three-electrode, two-current pathway, sequential pulse system. The first two electrodes, which are catheter-mounted, are located in the right ventricular apex (RVA) and superior vena cava (SVC). In sequential pulse defibrillation, one shock is delivered from the SVC to the RVA, followed 1 msec later by a second shock delivered from the third electrode to the RVA. Sequential pulse defibrillation threshold was obtained with each epicardial electrode used at each site. A single-pulse (SVC to RVA) catheter threshold was also obtained in each heart. The overall mean sequential pulse threshold was 47 per cent less than the mean single-pulse threshold (P less than 0.001). Increasing patch size reduced sequential pulse threshold (P less than 0.03), but no significant effect of patch location could be demonstrated. It is concluded that sequential pulse defibrillation is superior to single-pulse catheter defibrillation and that increasing epicardial patch size is advantageous, although patch location does not influence thresholds in the isolated heart.     

Performance evaluation of image segmentation algorithms on microscopic image data

In our paper, we present a performance evaluation of image segmentation algorithms on microscopic image data. In spite of the existence of many algorithms for image data partitioning, there is no universal and ‘the best’ method yet. Moreover, images of microscopic samples can be of various character and quality which can negatively influence the performance of image segmentation algorithms. Thus, the issue of selecting suitable method for a given set of image data is of big interest. We carried out a large number of experiments with a variety of segmentation methods to evaluate the behaviour of individual approaches on the testing set of microscopic images (cross‐section images taken in three different modalities from the field of art restoration). The segmentation results were assessed by several indices used for measuring the output quality of image segmentation algorithms. In the end, the benefit of segmentation combination approach is studied and applicability of achieved results on another representatives of microscopic data category – biological samples – is shown.