Use of the Bradley-Terry model to quantify association in remotely sensed images

Thematic maps prepared from remotely sensed images require a statistical accuracy assessment. For this purpose, the /spl kappa/-statistic is often used. This statistic does not distinguish between whether one unit is classified as another, or vice versa. In this paper, the Bradley-Terry (BT) model is applied for accuracy assessment. This model compares categories pairwise. The probability of one class over another class is estimated as well as the expected values of class pixels. The study is illustrated with an Advanced Spaceborne Thermal Emission and Reflection Radiometer image from the Netherlands, to which a maximum-likelihood classification with the Euclidean distance is applied. An error matrix is generated using an IKONOS image from the same area as ground truth. It is shown to which degree the BT model extends the /spl kappa/-statistic. A comparison with the Mahalanobis distance is made. Standardization is carried out to overcome problems emerging from the fact that a common BT model does not include the number of correctly classified pixels. The study shows how the BT model serves as an alternative to the usual /spl kappa/-statistic.     

Use of induced acceleration to quantify the (de)stabilization effect of external and internal forces on postural responses

Due to the mechanical coupling between the body segments, it is impossible to see with the naked eye the causes of body movements and understand the interaction between movements of different body parts. The goal of this paper is to investigate the use of induced acceleration analysis to reveal the causes of body movements. We derive the analytical equations to calculate induced accelerations and evaluate its potential to study human postural responses to support-surface translations. We measured the kinematic and kinetic responses of a subject to sudden forward and backward translations of a moving platform. The kinematic and kinetics served as input to the induced acceleration analyses. The induced accelerations showed explicitly that the platform acceleration and deceleration contributed to the destabilization and restabilization of standing balance, respectively. Furthermore, the joint torques, coriolis and centrifugal forces caused by swinging of the arms, contributed positively to stabilization of the Center of Mass. It is concluded that induced acceleration analyses is a valuable tool in understanding balance responses to different kinds of perturbations and may help to identify the causes of movement in different pathologies.     

Statistical approach to quantify the presence of phase coupling using the bispectrum

The bispectrum is a method to detect the presence of phase coupling between different components in a signal. The traditional way to quantify phase coupling is by means of the bicoherence index, which is essentially a normalized bispectrum. The major drawback of the bicoherence index (BCI) is that determination of significant phase coupling becomes compromised with noise and low coupling strength. To overcome this limitation, a statistical approach that combines the bispectrum with a surrogate data method to determine the statistical significance of the phase coupling is introduced. Our method does not rely on the use of the BCI, where the normalization procedure of the BCI is the major culprit in its poor specificity. We demonstrate the accuracy of the proposed approach using simulation examples that are designed to test its robustness against noise contamination as well as varying levels of phase coupling. Our results show that the proposed approach outperforms the bicoherence index in both sensitivity and specificity and provides an unbiased and statistical approach to determining the presence of quadratic phase coupling. Application of this new method to renal hemodynamic data was applied to renal stop flow pressure data obtained from normotensive (N = 7) and hypertensive (N = 7) rats. We found significant nonlinear interactions in both strains of rats with a greater magnitude of coupling and smaller number of interaction peaks in normotensive rats than hypertensive rats.     

A model to quantify the effects of sensitivity time control onradar-to-radar interference

This paper develops a method to calculate the effects of sensitivity time control (STC) on interference, experienced by one radar, caused by another radar. The probability density function (PDF) of STC attenuation is determined by, and is related to the overall probability distribution that determines the probability of interference. This method is consistent with, and complementary to the method of calculating the effects of antenna-to-antenna coupling between the radars     

Measures to quantify the gain of multicast with application to IPTV transmissions via WiMAX networks

In applications like IPTV, multicasting provides beneficial services. However, due to overhead and problems of multicast transmission, multicasting is not always profitable. In order to make well-justified decisions whether it is worthwhile to use multicasting or not, its efficiency must be quantified. Therefore, the metric of ‘multicast gain’ is introduced as a measure for the bandwidth reduction which can be expected when using multicast (instead of multiple unicast). Different definitions for multicast gain are given to cover different types of links. As an application of our metric, multicast transmission of live TV channels in WiMAX-based access networks is analyzed. WiMAX as one of the 4G candidates can transmit IPTV services to mobile subscribers because of salient features such as multicast support, wide coverage range and high bandwidth. In OFDMA-based WiMAX the smallest logical bandwidth allocation unit is a slot. In this article, we use the term slot to measure the efficiency of multicasting in WiMAX networks. We show that for unpopular TV channels, using unicast flows can be preferable.     

Use of the Dempster-Shafer algorithm for the detection of SAR shipwakes

An automatic detection algorithm (ADA) for synthetic aperture radar (SAR) ship wakes, based upon the Dempster-Shafer algorithm, is described and applied to a large set of SEASAT wake imagery. The SEASAT images were chosen specifically to test the limitations of the ADA. Images exhibiting multiple SAR ship wakes, short or faint wake features, striated ocean backgrounds, or the presence of other naturally occurring linear ocean features, constituted the majority of images. The ADA correctly classified the majority of the images, with misclassifications linked largely to very short or faint linear features. The ADA performed very well in striated ocean regions and in areas where the wake features were competing with naturally occurring linear ocean structure     

我国现阶段建设项目跟踪审计现状研究

随着我国社会控制成本意识的提高,为了有效控制工程项目建设及运营成本,提高投资效益,开展建设项目跟踪审计是必要的。但由于受到审计力量约束、国家制度建设、新事物的摸索等原因,跟踪审工作的各阶段包括咨询专业、合同模式、行业规定、工作权责、监督协调等均存在很多的问题,应通过行业立法、规范审计模式等加以解决。     

光栅数显位移测量系统

本文简要介绍了光栅莫尔条纹信号的产生及其测量原理,详细分析了莫尔条纹信号的放大整形,计数及数码显示电路。并且采用可编程逻辑器件GAL16V8实现莫尔条纹信号的四细分及辨向功能,极大地简化了电路,提高了系统的抗干扰能力。本设计主要是针对现有旧的长度/高度测试仪进行改造,实现其数字化显示,以及测量清零等周边功能,使用更方面,同时也提高了测量的精度。改变了原有只进行的定性检测（仅检测合格/不合格）的检测方法,实现了定量的检测与分析。通过实验结果可知,此系统可达到10μm的精度。     

A novel measurement technique to assess the effects of coronary brachytherapy in clinical trials

This paper presents a novel measurement technique to assess the effects of coronary brachytherapy. This new technique is based upon the conventional quantitative coronary analysis (QCA) technique, which is accepted worldwide as an accurate and reliable analysis tool for clinical trials. This paper provides the definitions and main issues important for correct brachytherapy analysis. Based on these definitions, this novel technique is implemented as an extension of conventional QCA software, as a multisegmental analysis tool. It allows to follow the influence of radiation on restenosis, and the mutual relation between intervention devices. A pilot interobserver study was performed to assess the reliability and reproducibility of the brachytherapy analysis tool, using 15 patient cases. The validation results show that the segment lengths, minimum lumen diameter, and reference diameters of the user-defined and derived (sub)segments can be assessed reproducible. However, these good results can only be obtained, when strict and extensive image acquisition and image analysis protocols are followed. From this pilot validation study presented in this paper and only based on a small number of patients, we may conclude that the software can be applied to clinical trials.     

A registration-based approach to quantify flow-mediated dilation (FMD) of the brachial artery in ultrasound image sequences

Flow-mediated dilation (FMD) offers a mechanism to characterize endothelial function and, therefore, may play a role in the diagnosis of cardiovascular diseases. Computerized analysis techniques are very desirable to give accuracy and objectivity to the measurements. Virtually all methods proposed up to now to measure FMD rely on accurate edge detection of the arterial wall, and they are not always robust in the presence of poor image quality or image artifacts. A novel method for automatic dilation assessment based on a global image analysis strategy is presented. We model interframe arterial dilation as a superposition of a rigid motion and a scaling factor perpendicular to the artery. Rigid motion can be interpreted as a global compensation for patient and probe movements, an aspect that has not been sufficiently studied before. The scaling factor explains arterial dilation. The ultrasound sequence is analyzed in two phases using image registration to recover both transformation models. Temporal continuity in the registration parameters along the sequence is enforced with a Kalman filter since the dilation process is known to be a gradual physiological phenomenon. Comparing automated and gold standard measurements (average of manual measurements) we found a negligible bias (0.05%FMD) and a small standard deviation (SD) of the differences (1.05%FMD). These values are comparable with those obtained from manual measurements (bias = 0.23%FMD, SD(intra-obs) = 1.13%FMD, SD(inter-obs) 1.20%FMD). The proposed method offers also better reproducibility (CV = 0.40%) than the manual measurements (CV = 1.04%).     

Use of spectral analysis in the detection of frequency differencesin the electrogastrograms of normal and diabetic subjects

The authors investigated the basal electrical rhythm (BER) of the stomach to determine if abnormalities of the BER occur in association with those gastric complaints in patients with long-term insulin-dependent diabetes. They recorded the basal electrical signal of the stomach in nine patients with diabetic gastroparesis and in 11 normal volunteers. They developed a microcomputer-based running spectral analysis technique (overlapping fast Fourier transforms) to analyze the recordings. They found no significant differences between the two subject groups in the prefed state but found a significantly higher proportion of episodes of high frequency, or tachygastria in the diabetic group in the postfed state (15.4-6.2%). The difference was also reflected in the higher postfed mean `peak' frequency of the diabetics. Both diabetics and normals show an increase in the mean of the peak frequency from pre- to postfed states, but the normals do not show an increase in episodes of tachygastria     

Ge-on-Si approaches to the detection of near-infrared light

We review our recent results on Ge-based near-infrared photodetectors grown on silicon. We fabricated metal-semiconductor-metal photodetectors based on epitaxial pure-Ge grown on silicon by chemical vapor deposition. Material characterization and device performances are illustrated and discussed. Exploiting a novel approach based on evaporation of polycrystalline-Ge on silicon, we also realized efficient near-infrared photodiodes with good speed and sensitivity. Finally, multiple-element devices were designed, fabricated, and tested, such as a voltage-tunable wavelength-selective photodetector based on a SiGe superlattice and a linear array of 16 photodetectors in poly-Ge on Si     

Use of ellipsometry to characterize the surface of HgCdTe

Ellipsometry is a sensitive, rapid, and nondestructive optical technique for characterizing materials, especially surfaces and films. By measuring the change in the state of polarization of a light beam reflecting from the sample, one may infer certain characteristics of the sample. We present a review of the applications of ellipsometry to HgCdTe and related materials. The fundamentals of the technique are discussed briefly and the optical parameters at the wavelength 6328A for several materials of interest to infrared technology are listed. The emphasis of this paper is on the interpretation of the ellipsometric data, expressed in terms of the usual parameters Ψ and Δ obtained at a single wavelength. Methods and limitations of the analysis of single films, both nonabsorbing and absorbing, are discussed. Examples of an acceptance window for process monitoring are presented. The ellipsometric signatures of amorphous Te films and microroughness are described, along with a graphical method for interpreting the readings from very thin films. Spectroscopic applications and in situ monitoring of molecular beam epitaxial growth processes are briefly reviewed.     

利用铁塔公司站址资源实现大气监测功能

陕西铁塔公司充分发挥公司现有站址的规模和应用优势,利用铁塔公司大量的存量站址资源,实现大气监测功能。对方案实施的关键点和相关工程预算进行了详细的说明,可作为铁塔公司大气监测新业务的方案指导。     

Approach to the Practical Use of Thermoelectric Power Generation

The results of research and development in the Japanese national project “Development for Advanced Thermoelectric Conversion Systems” are summarized, and the approaches to practical use of advanced thermoelectric modules and power generation systems are presented. The 5-year national project was successfully completed in March 2007. Three kinds of high- efficiency cascaded thermoelectric modules and two kinds of innovative Bi-Te thermoelectric modules were successfully developed. Heat cycle tests for three types of modules were also completed. Moreover, four types of advanced thermoelectric power generation systems were experimentally demonstrated for recovery of waste heat from the industrial and private sectors. In order to proceed further, thermoelectric power generation systems using practical heat sources were followed after installation of the developed modules. In parallel, various approaches for practical use by private companies, as well as plans for the next-phase project by the National Institute of Advanced Industrial Science and Technology (AIST) and the Engineering Advancement Association (ENAA), were also followed. The scenarios to proceed to the commercial phase of thermoelectric power generation are discussed on the basis of the results of the national project.     

使用信道预测技术提高HSDPA系统性能

HSDPA(High Speed Downlink Packet Access：高速下行分组接入)是第三代移动通信系统WCDMA(Wideband Code Division Multiple Access)的演化技术。本文提出应用信道载干比预测技术，为HSDPA系统提供信道的将来信息，从而减小实际中载干比估计的误差。仿真结果表明信道预测技术可以有效提高系统的吞吐量。     

黎曼和在体积计算中的应用

本文论述了非接触测量中不规则物体测量系统的体积计算方法和实践。在已知空间物体表面区域方程的前提下，利用黎曼和可以方便地求出被测物体的体积。     

有线电视放大器的正确使用

从放大器的分类及特点、同轴电缆及分支器对电视信号的传输特性、放大器的最小输入电平、放大器的输出电平和使用放大器的注意事项5个方面叙述了如何正确使用有线电视放大器。     

如何利用SDH网络对交换网的同步定时进行改造(上)

本文简要介绍了同步及同步网相关知识，通过实际测试的结果给出了SDH传送定时的具体要求和相关参数，施工时需要注意的问题，并结合A市交换同步定时改造实例，详细讲解如何通过SDH网络解决PDH退网后交换局同步信号的传送问题。文章中同时详细介绍了朗讯、NEC、华为三种传输SDH设备时钟输入和输出端口的连接方法以及AXE10、EWSD、华为、S1240、中兴五种交换机型同步定时的具体改造方法，对交换机同步信号改造有现实的指导意义。