利用VB编程实现实时数据曲线绘制

实时动态数据曲线的绘制与显示，是各种工业测控系统的重要功能。而实现方法也不尽相同。提出了一种基于VB编程，简单易懂的实时数据曲线绘制方法，实际使用证明完全能够满足实时监控要求。文中通过一个实例介绍了其实现的具体方法。     

Robust nonrigid registration to capture brain shift from intraoperative MRI

We present a new algorithm to register 3-D preoperative magnetic resonance (MR) images to intraoperative MR images of the brain which have undergone brain shift. This algorithm relies on a robust estimation of the deformation from a sparse noisy set of measured displacements. We propose a new framework to compute the displacement field in an iterative process, allowing the solution to gradually move from an approximation formulation (minimizing the sum of a regularization term and a data error term) to an interpolation formulation (least square minimization of the data error term). An outlier rejection step is introduced in this gradual registration process using a weighted least trimmed squares approach, aiming at improving the robustness of the algorithm. We use a patient-specific model discretized with the finite element method in order to ensure a realistic mechanical behavior of the brain tissue. To meet the clinical time constraint, we parallelized the slowest step of the algorithm so that we can perform a full 3-D image registration in 35 s (including the image update time) on a heterogeneous cluster of 15 personal computers. The algorithm has been tested on six cases of brain tumor resection, presenting a brain shift of up to 14 mm. The results show a good ability to recover large displacements, and a limited decrease of accuracy near the tumor resection cavity.     

Managing the network state evolution over time using CORBAenvironment

This paper proposes a CORBA-based framework for managing the network state evolution over time. This framework is based on the concept of CORBA temporal agents, capable of managing the past and current behavior of network resources. Managed objects use specific time attributes for representing how their values are evolving in time. Moreover, specially designed operations (services) enable users to exploit the temporal dimension of management information in order to understand the past, control the present, and thus even predict the future of managed objects. The management environment is designed in order to provide coexistence and interoperability with existing management platforms     

Pulse shape evolution and noise estimates in concatenated fiberlinks using analog optoelectronical repeaters

The pulse shape evolution in a chain consisting of dispersive fiber segments concatenated by analog optoelectronical repeaters is investigated. Analytical results based on a linear propagation model and Gaussian pulse shape with linear chirp as well as more realistic simulations, taking into account different pulse shapes and fiber nonlinearities, show that analog optoelectronical repeaters allow a significant improvement in the dispersion accumulation along the chain compared with all-optical amplification. To transmit data sequences, return-to-zero modulation has to be applied and simulations show that 10 Gb/s data can be transmitted at least over a distance of 1000 km with an power penalty caused by dispersion of 0.7 dB only. However, the noise accumulation reduces this length. For sufficiently large number of fiber segments with realistic parameters, the all-optical amplification performs better from a noise point of view     

Motion estimation in ultrasound images using time domain cross correlation with prior estimates

In this paper we introduce a new speckle tracking method that is based on the standard time-domain cross correlation strain estimation (TDE). We call this method time-domain cross-correlation with prior estimates (TDPE), because it uses prior displacement estimates of neighboring windows to speed up computation. TDPE has all the advantages of TDE, but is much faster. Simulations, as well as experiments with phantoms and tissue, indicate that TDPE is capable of reliably estimating tissue displacement and strain over a large range of displacements in real time. The computational efficiency of TDPE is compared with current time-efficient methods that have been used in real time strain imaging systems. The results show that TDPE is the most time efficient algorithm to date, and is roughly 10 times faster than the TDE. The implementation of TDPE on an Ultrasonix RP500 ultrasound machine runs at 30 fps for strain images of 16 000 pixels.     

A nonparametric statistical method for image segmentation using information theory and curve evolution.

In this paper, we present a new information-theoretic approach to image segmentation. We cast the segmentation problem as the maximization of the mutual information between the region labels and the image pixel intensities, subject to a constraint on the total length of the region boundaries. We assume that the probability densities associated with the image pixel intensities within each region are completely unknown a priori, and we formulate the problem based on nonparametric density estimates. Due to the nonparametric structure, our method does not require the image regions to have a particular type of probability distribution and does not require the extraction and use of a particular statistic. We solve the information-theoretic optimization problem by deriving the associated gradient flows and applying curve evolution techniques. We use level-set methods to implement the resulting evolution. The experimental results based on both synthetic and real images demonstrate that the proposed technique can solve a variety of challenging image segmentation problems. Futhermore, our method, which does not require any training, performs as good as methods based on training.     

利用单光子探测器测量多光子响应时间

通过研究单光子探测器对微弱激光脉冲的暂态响 应特性,利用不同光子数的响应时间实现光 子数的分辨测量。理论上分析了光子数响应时间与微弱光脉冲探测时间的对应关系。实验上 通过测量不同光强下单光子探测器的暂态响应,测量到1550nm波段单光子、 双光子和三光子的响应时间分别为10.73±0.17、8.75±0.32和5.98±0.77ns。实现精确区分微弱光场中的光子数。分析了单光子探测器光子数统计涨落引起的 微弱激光脉冲的探测时间变化对光子数响应时间测量的影响。     

Contour extraction from cardiac MRI studies using snakes

The author investigated automatic extraction of left ventricular contours from cardiac magnetic resonance imaging (MRI) studies. The contour extraction algorithms were based on active contour models, or snakes. Based on cardiac MR image characteristics, the author suggested algorithms for extracting contours from these large data sets. The author specifically considered contour propagation methods to make the contours reliable enough despite noise, artifacts, and poor temporal resolution. The emphasis was on reliable contour extraction with a minimum of user interaction. Both spin echo and gradient echo studies were considered. The extracted contours were used for determining quantitative measures for the heart and could also be used for obtaining graphically rendered cardiac surfaces.     

Parameter extraction and electrical characterization of highdensity connector using time domain measurements

Two coupled connector pins can be represented by an equivalent circuit consisting of six parameters, namely, self capacitance/self inductance per pin, mutual capacitance between pins and mutual inductance between pins. A systematic parameter extraction algorithm has been discussed in this paper using time domain reflectometry (TDR) measurements. This method uses a combination of stand-alone, common mode, and differential mode measurements to extract the connector parasitics. The accuracy of the equivalent circuit has been studied in detail using crosstalk measurements     

The boundary shift integral: an accurate and robust measure ofcerebral volume changes from registered repeat MRI

We propose the boundary shift integral (BSI) as a measure of cerebral volume changes derived from registered repeat three-dimensional (3-D) magnetic resonance (MR) [3D MR] scans. The BSI determines the total volume through which the boundaries of a given cerebral structure have moved and, hence, the volume change, directly from voxel intensities. We found brain and ventricular BSI's correlated tightly (r=1.000 and r=0.999) with simulated volumes of change. Applied to 21 control scan pairs and 11 scan pairs from Alzheimer's disease (AD) patients (mean interval 386 days) the BSI yielded mean brain volume loss of 1.8 cc (controls) and 34.7 cc (AD); the control group was tightly bunched (SD=3.8 cc) and there was wide group separation, the group means differing by 8.7 control group standard deviations (SDs). A measure based on the same segmentation used by the BSI yielded similar group means, but wide spread in the control group (SD=13.4 cc) and group overlap, the group means differing by 2.8 control group SDs. The BSI yielded mean ventricular volume losses of 0.4 cc (controls) and 10.1 cc (AD). Good linear correlation (r=0.997) was obtained between the ventricular BSI and the difference in their segmented volumes. We conclude the BSI is an accurate and robust measure of regional and global cerebral volume changes     

A MECS redistribution algorithm for SDN-enable MEC using response time and transmission overhead

Wireless Networks - The software-defined networks-enable mobile edge computing (SDN-enable MEC) architecture, which integrates SDN and MEC technologies, realizes the flexibility and dynamic...     

Left ventricular deformation recovery from cine MRI using an incompressible model

This paper presents a method for 3-D deformation recovery of the left ventricular (LV) wall from anatomical cine magnetic resonance imaging (MRI). The method is based on a deformable model that is incompressible, a desired property since the myocardium has been shown to be nearly incompressible. The LV wall needs to be segmented in an initial frame after which the method automatically determines the deformation everywhere in the LV wall throughout the cardiac cycle. Two studies were conducted to validate the method. In the first study, the deformation recovered from a 3-D anatomical cine MRI of a healthy volunteer was compared against the manual segmentation of the LV wall and against the corresponding 3-D tagged cine MRI. The average volume agreement between the model and the manual segmentation had a false positive rate of 3%, false negative rate of 3%, and true positive rate of 93%. The average distance between the model and manually determined intersections of perpendicular tag planes was 1.6 mm (1.1 pixel). Another set of 3-D anatomical and tagged MRI scans was taken of the same volunteer four months later. The method was applied to the second set and the recovered deformation was very similar to the one obtained from the first set. In the second study, the method was applied to 3-D anatomical cine MRI scans of three patients with ventricular dyssynchrony and three age-matched healthy volunteers. The LV wall deformations recovered for the three normals agreed well and the recovered strains were similar to those reported by other researchers for normal subjects. Strains and displacements of the three patients were clearly smaller than those of the three normals indicating reduced cardiac function. The deformation recovered for the three normals and the three patients was validated against manual segmentation and corresponding tag cine MRI scans and the agreement was similar to that of the first validation study.     

Three-dimensional myocardial strain reconstruction from tagged MRI using a cylindrical B-spline model

In this paper, we present a new method for reconstructing three-dimensional (3-D) left ventricular myocardial strain from tagged magnetic resonance (MR) image data with a 3-D B-spline deformation model. The B-spline model is based on a cylindrical coordinate system that more closely fits the morphology of the myocardium than previously proposed Cartesian B-spline models and does not require explicit regularization. Our reconstruction method first fits a spatial coordinate B-spline displacement field to the tag line data. This displacement field maps each tag line point in the deformed myocardium back to its reference position (end-diastole). The spatial coordinate displacement field is then converted to material coordinates with another B-spline fit. Finally, strain is computed by analytically differentiating the material coordinate B-spline displacement field with respect to space. We tested our method with strains reconstructed from an analytically defined mathematical left ventricular deformation model and ten human imaging studies. Our results demonstrate that a quadratic cylindrical B-spline with a fixed number of control points can accurately fit a physiologically realistic range of deformations. The average 3-D reconstruction computation time is 20 seconds per time frame on a 450 MHz Sun Ultra80 workstation.     

Developing the stress–strain curve to failure using mesoscale models parameterized from molecular models

Developing the stress response using the molecular and mesoscale levels is fairly reliable during the initial strain. For instance, modulus is a property that can be established using these techniques and the continuity of scale between the molecular and mesoscale and agreement with experiment suggests that both may be used to establish modulus for parameterizing a macroscale model when measured properties are unavailable. However, the latter part of the stress–strain response that helps to establish ties to crack propagation still needs attention. One problem that was previously found in the mesoscale models was questionable lack of void formation in crosslinked systems due to superficially clean adhesive separation in the simulations. One way to overcome this lack of voiding was to determine how to develop bond breakage criterion that would allow surfaces to develop. This paper discusses development and application of bond breakage on a mesoscale level (which uses a bead-bond breakage criterion so does not explicitly define which bond is broken), and the impact on the simulated stress–strain curves using mesoscale models.     

Effects on response time performance using an edge-to-edge protocolin an X.25 packet network

Results presented in earlier work (IEEE J. Sel. Areas Commun. vol.6, no.1, p.190-6, 1988) in which an edge-to-edge protocol was supported between network gateways are reviewed and extended. Emphasis was placed on studying effects of varying the protocol, and, in particular, varying the acknowledgement methods used in window flow-control. The results were obtained with a simulation of a small packet network in which the full X.25 LAPB link protocol was coded in detail on every link in the network. The simulation stepped through each link in half-millisecond time increments, using a Monte Carlo technique to generate data from users and noise on the links. For the current study, an edge-to-edge protocol has been implemented separately for every virtual circuit in the network. Results of the simulation for a three-switch network are presented. The primary measure of performance is the user-perceived round-trip response time from the start of input of a message to completion of a reply from the message destination     

A novel approach for coefficient quantization of low-pass finite impulse response filter using differential evolution algorithm

Evolutionary computational techniques have been employed judiciously in various signal processing applications of late. In this paper, such an attempt has been made to design a low-pass linear-phase multiplier-less finite duration impulse response (FIR) filter using differential evolution (DE) algorithm. This particular evolutionary optimization technique has been explored to search the impulse response coefficients of the FIR filter in the form of sum of power of two (SPT) in order to avoid the multipliers during design process. The performance of the designed low-pass filter has been studied thoroughly in terms of its frequency characteristics and primitive requirement of fundamental hardware blocks. The superiority of our design has been ascertained over a number of existing techniques by various means. Finally, the proposed filter of different lengths has been implemented on a field programmable gate array (FPGA) chip for evaluating the competency of this work. The percentage improvement in hardware complexity produced by our design has also been computed and clearly listed in this paper for convenience.     

Myocardial blood flow quantification from MRI by deconvolution using an exponential approximation basis

We have evaluated the use of deconvolution using an exponential approximation basis for the quantification of myocardial blood flow from perfusion cardiovascular magnetic resonance. Our experiments, based on simulated signal intensity curves, phantom acquisitions, and clinical image data, indicate that exponential deconvolution allows for accurate quantification of myocardial blood flow. Together with automated respiratory motion correction myocardial contour delineation, the exponential deconvolution enables efficient and reproducible quantification of myocardial blood flow in clinical routine.     

Steady state thermal characterization and junction temperatureestimation of multichip module packages using the response surfacemethod

The steady state thermal performance of semiconductor packages has been traditionally reported through the utilization of a single junction-to-ambient thermal resistance constant commonly referred to as &thetas;_ja. This is particularly inadequate for multichip modules where several devices reside within the same package structure. This paper discusses how a central composite design of experiments can be applied to provide a more accurate thermal characterization of a multichip module package. The end product is a series of linear or polynomial equations which can be utilized by the customer to calculate individual device junction temperatures over a wide variation of convection cooling environments and multiple device power dissipations. A 352 plastic ball grid array package, which encompasses three individual integrated circuit devices, is used as an example. The paper steps through the sensitivity analysis and evaluates the accuracy of the resulting equations. This method of thermal characterization can be easily applied to single chip modules of varying power and cooling regimes, or multiple output devices where several power junctions reside within the same integrated circuit     

Heart rate variability characterization in daily physical activities using wavelet analysis and multilayer fuzzy activity clustering

A portable data recorder was developed to parallel measure the electrocardiogram and body accelerations. A multilayer fuzzy clustering algorithm was proposed to classify the physical activity based on body accelerations. Discrete wavelet transform was incorporated to retrieve time-varying characteristics of heart rate variability under different physical activities. Nine healthy subjects were included to investigate activity-related heart rate variability during 24 h. The results showed that the heartbeat fluctuations in high frequencies were the greatest during lying and the smallest during standing. Moreover, very-low-frequency heartbeat fluctuations during low activity level (lying) were greater than during high activity level (nonlying).     

Calculation of transient response from frequency-response data using Cheby?shev polynomials

The method presented in this letter converts frequency-response data into an analytical expression for the impulse (step response) as a linear combination of polynomials whose coefficients are given. The constants of this linear combination are, instead, the coefficients of the Cheby?shev approximation of the real (or imaginary) part of the frequency response.