Estimation of regurgitant volume and orifice in aorticregurgitation combining CW Doppler and parameter estimation in aWindkessel-like model

A method for noninvasive estimation of regurgitant orifice and volume in aortic regurgitation is proposed and tested in anesthetized open chested pigs. The method can be used with noninvasive measurement of regurgitant jet velocity with continuous wave ultrasound Doppler measurements together with cuff measurements of systolic and diastolic systemic pressure in the arm. These measurements are then used for parameter estimation in a Windkessel-like model which include the regurgitant orifice as a parameter. The aortic volume compliance and the peripheral resistance are also included as parameters measurements in the open chest pigs are used. Electromagnetic flow measurements in the ascending aorta and pulmonary artery are used for control, and a correlation between regurgitant volume obtained from parameter estimation and electromagnetic flow measurements of 0.95 over a range from 2.1 to 17.8 mL is obtained.     

Frequency domain lifetime characterization

Time-based measurements are commonly used for lifetime characterization of semiconductors. We have developed the theory, verified by experiment, of frequency-based lifetime characterization as an alternative to time-based measurements for MOS devices biased in inversion. One consideration during lifetime/diffusion length measurements, is whether the near-surface space-charge region or the bulk or quasineutral region is characterized. To characterize the near-surface space-charge region of the device, one usually makes room temperature pulsed MOS capacitor or diode leakage current measurements. We show that room-temperature, frequency-domain capacitance, conductance, or resistance measurements characterize the quasineutral bulk, not the space charge region, in contrast to room-temperature pulsed MOS-C or diode leakage current measurements which characterize the space-charge region     

Automatic Construction of Building Footprints From Airborne LIDAR Data

This paper presents a framework that applies a series of algorithms to automatically extract building footprints from airborne light detection and ranging (LIDAR) measurements. In the proposed framework, the ground and nonground LIDAR measurements are first separated using a progressive morphological filter. Then, building measurements are identified from nonground measurements using a region-growing algorithm based on the plane-fitting technique. Finally, raw footprints for segmented building measurements are derived by connecting boundary points, and the raw footprints are further simplified and adjusted to remove noise caused by irregularly spaced LIDAR measurements. Data sets from urbanized areas including large institutional, commercial, and small residential buildings were employed to test the proposed framework. A quantitative analysis showed that the total of omission and commission errors for extracted footprints for both institutional and residential areas was about 12%. The results demonstrated that the proposed framework identified building footprints well.     

多假目标欺骗干扰下组网雷达跟踪技术

针对距离多假目标欺骗干扰下的组网雷达跟踪,提出了一种基于同源量测融合的跟踪技术.该跟踪技术包括同源量测融合、多目标跟踪两部分.同源量测融合相当于对所有量测进行预处理,其关键在于同源量测自适应检验门限的设计.通过该预处理,输入的假目标的量测数目大大减少,且问题简化为单雷达的多目标跟踪.多目标跟踪中,根据航迹优先级顺序依次进行数据关联.该跟踪技术使得组网雷达可以有效剔除假目标,并更精确的跟踪真目标.仿真结果证明了该技术的可行性和有效性.     

Multi‐model Switching for Car Navigation Containing Low‐Grade IMU and GPS Receiver

This letter presents a filter for a car navigation system integrating a low‐grade inertial measurements unit (IMU) and a global positioning system receiver. The filter is designed according to the state variables to be estimated and the usable measurements. The usable measurements change from case to case, and the estimative state variables also change due to the measurements; therefore, multiple models must be used for real environmental maneuvers. In this letter, four models for land navigation are chosen and switched by rearranging the system matrix and resetting the error covariance matrices.     

TD-SCDMA终端测量过程研究

先对TD-SCDMA终端七种类型的测量进行了介绍,然后基于高层协议对连接模式下的测量过程进行了描述,最后通过一个测试例具体分析了测量的详细实现过程,并给出了详细的流程图。     

Correlation and covariance of satellite scatterometer measurements

Capable scatterometer designs have been developed that seek improved resolution through the use of higher pulse sampling rates. The high sampling rates bring the traditional scatterometry assumption of measurement independence into question. This paper uses fundamental scattering theory to derive general expressions for correlation and covariance between scatterometer measurements and provides practical analysis using current and future instruments as examples. The paper derives expressions for the measurement variance parameter K/sub p/ when measurement correlation due to Rayleigh fading effects is present and relates K/sub p/ to the statistics of multiple pulse measurements. A function of the transmit signal modulation and receive processing, the measurement correlation is zero for nonoverlapping measurements but can become significant for overlapping measurements at high pulse sampling rates. The paper discusses the effects of correlation on the accuracy of scatterometer measurements and evaluates tradeoffs between spatial overlap, levels of additive noise, and measurement precision.     

DC and Microwave-Biased Photoconductive Response in CdS Crystals (Short Papers)

DC and microwave-biased measurements of the photoresponse spectrum of sulfur-sensitized CdS single crystals were made in a K-band (22-GHz) reflection bridge. The experimental arrangement was such that both dc and microwave measurements could be performed at different temperatures without changing the rest of the sample's environment. For the microwave measurements, the response spectra were narrower and shifted toward shorter wavelengths than for the dc measurements.     

In situ characterization of laser diodes from wide-band electrical noise measurements

The wide-band electrical noise characteristics of 0.8-, 1.3-, and 1.5-μm laser diodes have been studied theoretically and for the first time also experimentally. The electrical noise is related to the optical intensity noise behavior, and can therefore be used for in situ measurements and characterization of laser diodes. Since the measurements are performed without any optical components, undesired optical feedback is eliminated. The results show that several important laser parameters and characteristics can be extracted from purely electrical noise measurements. Among these are the relaxation frequency, the threshold current, the emission linewidth, optical feedback properties, and longitudinal mode hopping behavior. Good agreement between the noise theory and the electrical noise measurements has been obtained. An expression for obtaining both the spectral linewidth and lineshape from electrical noise measurements is also derived.     

基于相似性传播的天波雷达多路径量测聚类

电离层多层结构特性使得天波雷达(OTHR)与目标之间存在多条信号传播路径,进而可能对单目标产生多路径量测。该文考虑了天波雷达多路径量测聚类问题,其需要同时对多路径量测进行电离层传播路径辨识和聚类。由于天波雷达量测模型假设1个目标通过1种电离层传播路径至多产生1个量测,因此需要考虑多路径聚类约束。该文将相似性传播聚类扩展到多路径约束模型,并提出一种新的多路径相似性传播聚类算法。该算法通过构建多路径量测聚类的概率图模型,将聚类问题转化为概率图模型隐变量的推断问题,采用最大和置信传播算法近似求解聚类变量的最大后验概率。算法优点包括可以自动识别聚类团数目,单次消息传播的时间复杂度为量测个数和传播路径个数乘积的平方。仿真实验分析表明,所提算法较多路径多假设聚类算法具有更好的聚类性能。     

GPS performance in navigation

We discuss Global Positioning System (GPS) measurements available for civil use and algorithms for processing them to obtain real-time estimates of position and velocity. The main objective is to characterize the measurements and to demonstrate the levels of performance achievable with a single GPS receiver and with system augmentations which make corrections to the measurements available to the user in real time. Representative results with positioning accuracy levels ranging from tens of meters to centimeters are given based on actual measurements     

Antenna Effects in Depolarization Measurements

The depolarization of electromagnetic energy scattered from natural terrain has been of interest to experimenters and theoreticians for many years. However, the reported measurements have not agreed with theoreticaly predicted results. Boresight axial ratio has commonly been used as a figure of merit to describe the polarization isolation properties of the measurement system antennas. Since depolarization measurements from terrain involve extended targets which fill the full antenna beam, boresight axial ratio is often an inadequate measure of antenna polarization purity. This paper describes antenna isolation characteristics which impact the quality of the depolarized measurements. Representative calculations demonstrate the effects of nonideal antenna systems on the observed measurements. A criterion for antenna specification is given which will provide high-quality cross-polarized measurements.     

A technique for elimination of reflected rays from antenna measurements performed in echoic environment

The paper describes a technique for analyzing antenna measurements and removing reflected components present in measurements performed in echoic environments. The method is based on digital signal processing methods, and frequency-domain measurements are used to design a discrete-time, finite impulse response digital filter using least-squares methods. The frequency response of the filter is equal to the transmission coefficient measurements performed in an anechoic chamber. In order to verify the method, processed measurements of mutual coupling between stacked patch antennas were compared to the computer simulations of anechoic response, and a very close agreement was achieved.     

Synergic inversion technique for active and passive microwaveremote sensing of the ocean

A unified approach for combining active and passive microwave measurements for remote sensing applications is described. A synergic inversion technique has been developed and applied to the retrieval of geophysical parameters of the ocean surface and of the atmosphere. It is based on the combination of radiometric and radar measurements at the electromagnetic and cell level and not only on the correction of radar measurements by radiometric measurements, or conversely. Such a combination is performed through a common quantity: the bistatic scattering coefficient of the observed surface. This is used in a direct model to simulate combined measurements from active and passive sensors. It requires a rather complete and accurate calculation of the scattering of microwaves by the rough sea surface     

Scalable diagnosis in IP networks using path-based measurement and inference: A learning framework

In this paper, we investigate scalability and performance of measurement-based network monitoring, focusing on failure and congestion diagnosis in IP networks for network-based multimedia applications. Path-based measurements using unicast probe-packets are obtained at end-hosts, and diagnosis is performed by exploiting the spatial dependence among those measurements. We formulate network monitoring in a machine learning framework using probabilistic graphical models which perform inference of the network states (on/off) using unicast measurements. We provide fundamental limits on the relationship between the number of probe packets, the size of a network and the ability to diagnose either failed links or congested network components. Specifically, the diagnosis problem is dealt in a two-fold manner. Initially for fault diagnosis, we construct a graphical model using a Bayesian belief network for path-based measurements. We then provide a lower bound on the average number of probes per edge for link failure diagnosis using variational inference under “noisy” probe measurements. Variational inference provides a feasible approximation to address the number of spatially dependent measurements needed for diagnosis in large networks. We then develop an entropy lower (EL) bound by drawing similarities between coding over a binary symmetric channel (BSC) and link failure diagnosis. Both bounds show that the number of measurements needed for diagnosis grows linearly with respect to the number of links. The analytical results are validated by simulation. On the other hand, for congestion diagnosis, we propose a solution based on decoding of linear error control codes on a BSC. In this scenario, we consider path-based probing experiments under both noiseless and “noisy” measurements and compare its performance against the fundamental limits. To identify the congested nodes we construct a factor graph, and congestion is inferred using belief-propagation algorithm. Simulation results demonstrate the ability of our approach to perfectly localize congested nodes using a scalable number of measurements and a computationally efficient algorithm. We believe that this study can ease the problem arising due to lack of QoS support and provide good-quality broadband multimedia services.     

Dual frequency scintillation measurement for remote sensing

A scheme is proposed for utilising measurements of radiowave amplitude scintillation at two frequencies for remote sensing of wind speed and atmospheric turbulence parameters. The main advantage of the method is that all quantities are estimated solely from measured scintillation parameters without the need for secondary measurements. It is shown that the method yields results which compare well with other measurements     

A Three-Dimensional Finite-Difference Solution of the External Response of an Aircraft to a Complex Transient EM Environment: Part I-The Method and Its Implementation

Experimental charge and current measurements have recently been performed on an aircraft when it was exposed to the transient electromagnetic fi'eld of an electromagnetic pulse (EMP) simulator. These new data allow a test of the predictive capabilities of the three-dimensional finite-difference method for realistic aircraft simulator test problems. In the paper, the workings of the threedimensional finite-difference method and its required inputs and sensitivity to variations in the inputs are discussed in sufficient detail to enable others to employ the method. A companion paper compares the experimental measurements to predictions for a large variety of measurement locations. Agreement is shown to be good for all major response measurements and satisfactory for a number of other measurements.     

Magnetic field measurements of the LHC-IR MQXA magnets at room temperature

KEK has completed 13 of the 18 MQXA quadrupole magnets supplied for the LHC interaction region. The field measurements at room temperature were performed before and after the cold test. The multipole components by the warm measurements showed a good correlation with those by the cold measurements. It is concluded that field quality of the magnets can be evaluated by the warm measurements.     

Integrated GPS/GLONASS navigation: Algorithms and results

The presence of selective availability (SA) on GPS has led to a variety of proposals for mitigation of its effects, for example combining GPS with other sensors or by identifying and removing the SA using redundant information in the position solution. A further method for reducing the impact of SA is the combination of GPS and GLONASS measurements. GLONASS does not have any deliberate degradation. This paper describes several algorithms for combining GPS and GLONASS measurements in real time on a single receiver. There are two least squares solutions using the code phase measurements alone: one with the measurements from both systems weighted equally, and one with the measurements weighted by the covariance of the measurements. Kalman filters with no SA model, and first- and second-order models, using both the code and carrier phase to estimate user position and velocity, are also implemented. Two different adaptive schemes are compared which attempt to identify SA model parameters in real time. The algorithms are compared in terms of their positioning accuracy, computational overhead and robustness. A ten-channel GPS/GLONASS receiver developed at The University of Leeds is used to provide satellite data for the evaluation of the different methods.     

Design and performance of a noncontacting probe for measurements onhigh-frequency planar circuits

Optimal design of a noncontacting magnetic probe for measurements on the interior of planar high-frequency circuits has been studied, and performance of the probe has been determined. The design was studied using enlarged models tested at frequencies 100 times lower than those of the actual intended use. The nature of its errors has been investigated, and some techniques for error reduction have been found. The accuracy of measurements on circuits with SWR <3.0 is typically 0.8 dB in magnitude and 7° in phase. S-parameter measurements on general two-ports can also be made by using the probe at several different positions on the associated transmission lines. The technique effectively eliminates the problem of de-embedding that arises in other kinds of S-parameter measurements. Examples of measurements with the large model probe are presented and compared with theory. Performance appears to be acceptable for the intended applications