Image reconstruction and multidimensional field estimation from randomly scattered sensors.

Many important problems in statistical signal processing can be formulated as function estimation from randomly scattered sensors in a multidimensional space, e.g., image reconstruction from photon-limited images and field estimation from scattered sensors. We present a novel approach to the study of signal reconstruction from random samples in a multidimensional space. In particular, we study a classical iterative reconstruction method and demonstrate that it forms a sequence of unbiased estimates for band-limited signals, which converge to the true function in the mean-square sense. We subsequently rely on the iterative estimation method for multidimensional image reconstruction and field estimation from sensors scattered according to a multidimensional Poisson and uniform distribution. Computer simulation experiments are used to demonstrate the efficiency of the iterative estimation method in image reconstruction and field estimation from randomly scattered sensors.     

A comparison of deconvolution and windowed subtraction techniques for scatter compensation in SPECT

Three procedures for the removal of Compton-scattered data in SPECT by constrained deconvolution are presented. The first is a deconvolution of a 2-D measured PSRF containing scatter from a single reconstructed transaxial image; the second is a deconvolution of a 2-D measured point-source response function (PSRF) from each frame of projection data prior to reconstruction; the third involves deconvolution of a 3-D measured PSRF from a stack of reconstructed slices. Results of applying these procedures to data obtained from a phantom containing cold cylinders and to data from a cold spot-resolution phantom are presented and are shown to be superior to the results of correcting for scatter by scatter-window substraction. Both 3-D deconvolution from reconstructed images and 2-D deconvolution from projection data show major improvements in image contrast, resolution, and quantitation. Improvements are especially marked for small (1.0-3.0 cm) cold sources.     

Dual-parameter radar rainfall measurement from space: a test resultfrom an aircraft experiment

An aircraft experiment has been conducted with a dual-frequency ( X/Ka-bands) radar to test various rainfall retrieval methods from space. The authors test a method to derive raindrop size distribution (DSD) parameters from the combination of a radar reflectivity profile and a path-integrated attenuation derived from the surface return, which may be available from most spaceborne radars. The test results indicate the feasibility of the dual-parameter radar measurement from space in achieving a better accuracy in quantitative rainfall remote measurements     

Locating Intersections for Autonomous Vehicles: A Bayesian Network Approach

A novel idea is presented to locate intersections in a video sequence captured from a moving vehicle. More specifically, we propose a Bayesian network approach to combine evidence extracted from a video sequence and evidence from a database, maximizing evidence from various sensors in a systematic manner and locating intersections robustly.     

Switching response of graded-base PN junction diodes

This paper extends the earlier analysis by Kingston of the switching response of a uniform-base diode to a graded-base diode. It concerns the time required to switch a diode from a forward-biased to a reverse-biased condition. The current transient can be separated into two phases: 1) the constant current phase during which the carrier density at the junction changes gradually from a forward-biased to a reverse-biased condition, and 2) the nonconstant current phase during which the injected carriers stored in the base region gradually disappear. In the present analysis, it is found that in a graded-base diode where the impurity concentration decreases from the emitter junction towards the base contact, the time for the constant current phase is greatly shortened because of favorable initial carrier distribution. The effect is already significant if the impurity concentration changes by a factor from 3 to 1 from the emitter junction to the base contact. To shorten the nonconstant current phase, however, a much larger change of impurity concentration, say of the order from 500 to 1, from the emitter junction to the base contact is needed.     

Measurements of Dielectric Constant of Volcanic Ash Erupted From Five Volcanoes in Japan

The dielectric properties of volcanic ash from five volcanoes in Japan were measured by using the transmission/reflection coaxial line method of a network analyzer, in a frequency range from 3 to 13 GHz. The measured permittivity of powdered ash was then converted to that of solid ash (dense rock equivalent) with the aid of effective medium theory. The values of solid-ash relative permittivities for the five volcanoes revealed that they were in a relatively narrow range. Their real part was generally in a range from five to six in magnitude, while their imaginary part was in a range from 0.08 to 0.18.      

Electromagnetic interference from discharge phenomena of electriccontacts

The electromagnetic interference (EMI) from steady arc and showering arc electrical discharges was investigated. The experiment was carried out on Ag, Pd, and Ag-Pd alloy contacts under several circuit current conditions. Radiated noise levels were measured at frequencies up to 200 MHz. Experimental results show that the EMI levels from a steady arc, which is generally the phenomenon of the break of a noninductive circuit, are dependent on the composition of contact materials. The EMI levels from a showering arc, which is generally the phenomenon of the break of an inductive circuit, are independent of the composition of contact materials. The EMI from a steady arc is roughly inversely proportional to the frequency in the 0.1-10.0-MHz range, whereas in the 25-200-MHz range, the maximum level of EMI appears at about 70 MHz. The frequency characteristics of EMI from a showering arc are similar to those from a steady arc. The EMIs from these arcs exceed, in part, statutory limits     

A Design of BASK System for Giga-bit Modem

We propose a binary amplitude shift keying (BASK) system of Giga-bit Modem without intermediate frequency process for the 60 GHz band. The proposed system consists of a high speed shutter of the transmitter and a repeater of the receiver. The shutter of the proposed system is introduced for pulse shaping to improve the intersymbol interference (ISI). The repeater consists of several stage converters. A converter is constructed with a low pass filter and a limiter. The repeater can improve the signal-to-noise ratio (SNR) and make the rectangular pulse train. The advantage of the proposed system is very simple without the intermediate frequency (IF) process. Ki-Hwan Eom was born in Seoul, Korea in 1949. He received the B.S. degree from Dongguk University, the M.S. degree from Inha University, and Ph.D. degree in electronic engineering from Dongguk University, Korea in 1972, 1975 and 1986, respectively. He was a visiting professor from 1989 to 1990 at Toho University, and from 2000 to 2001 at University of Canterbery. Since 1994, he has been with Dongguk University, where he is currently a Professor in the Department of Electronic Engineering. Seong-Ho Kang was born on September 5, 1972. He received the B.E. from JinJu National University in 2000 and Ph.D. degree from Dongguk University in 2006. His research interests are in communication systems and intelligent systems. Yoichi Sato was born on October 2, 1939. He received the B.E. from Kyoto University in 1963 and Ph.D. degree from Waseda University in 1976. From 1963 to 1982 he was a Research Engineer in the Central Research Labs. Of NEC Corporation. He joined Toho University in 1982. He is a Professor emeritus of the Department of Information Sciences in Toho University. He is a member of the IEEE Communication Society.     

High-Performance On-Chip Transformers With Partial Polysilicon Patterned Ground Shields (PGS)

In this brief, we propose the concept of "partial patterned ground shields (PGSs)" to improve the performances of RF passive devices, such as inductors and transformers. Partial PGS can be achieved after the redundant PGS of a traditional complete PGS, which is right below the spiral metal lines of an RF passive device, is removed for the purpose of reducing the large parasitic capacitance. A set of test transformers has been implemented to demonstrate the partial PGS. The results show that when the partial PGS was adopted, a 56.5% (from 6.12 to 9.58) and a 55.7% (from 5.55 to 8.64) increase in Q-factor, an 18.2% (from 0.67 to 0.79) and a 21.4% (from 0.66 to 0.8) increase in maximum available power gain (G_Amax), and an 18.4% (from 0.69 to 0.82) and a 21.2% (from 0.69 to 0.83) increase in magnetic-coupling factor (k_im) were achieved at 4.2 and 5.2 GHz, respectively, for a bifilar transformer with an overall dimension of 230times215 mum². Furthermore, compared with the transformer with traditional PGS, a 9.9% (from 10.1 to 11.1 GHz) increase in resonant frequency (f_SR), a 38% (from 6.94 to 9.58) increase in Q-factor at 4.2 GHz, and a 5.3% (from 0.75 to 0.79) increase in G_Amax at 4.2 GHz were obtained. These results demonstrate that the proposed partial PGS is very promising for high-performance RF-ICs applications     

Learning Color Names for Real-World Applications

Color names are required in real-world applications such as image retrieval and image annotation. Traditionally, they are learned from a collection of labeled color chips. These color chips are labeled with color names within a well-defined experimental setup by human test subjects. However, naming colors in real-world images differs significantly from this experimental setting. In this paper, we investigate how color names learned from color chips compare to color names learned from real-world images. To avoid hand labeling real-world images with color names, we use Google image to collect a data set. Due to the limitations of Google image, this data set contains a substantial quantity of wrongly labeled data. We propose several variants of the PLSA model to learn color names from this noisy data. Experimental results show that color names learned from real-world images significantly outperform color names learned from labeled color chips for both image retrieval and image annotation.     

Reconstructing polygons from moments with connections to arrayprocessing

We establish a set of results showing that the vertices of any simply connected planar polygonal region can be reconstructed from a finite number of its complex moments. These results find applications in a variety of apparently disparate areas such as computerized tomography and inverse potential theory, where in the former, it is of interest to estimate the shape of an object from a finite number of its projections, whereas in the latter, the objective is to extract the shape of a gravitating body from measurements of its exterior logarithmic potentials at a finite number of points. We show that the problem of polygonal vertex reconstruction from moments can in fact be posed as an array processing problem, and taking advantage of this relationship, we derive and illustrate several new algorithms for the reconstruction of the vertices of simply connected polygons from moments     

MIMO系统中的迭代分组MAP检测算法

该文提出了在分组MAP检测器内部进行干扰信息更新和检测信息迭代反馈的检测算法。在MIMO系统基本的分组MAP检测算法基础上,利用先检测分组产生的后验信息替代先验信息提高干扰信号的估计精确度,进一步可以使用迭代反馈的方法在检测器内部进行反馈检测分组的后验信息,从而提高了检测信号的分集度。仿真结果表明在未编码系统中改进的分组检测方法能够显著地提高系统误码率性能,在编码系统中能够加快整个系统的收敛。     

Synthesis of Resonator Filters With Arbitrary Topology Using Hybrid Method

This paper presents a new synthesis method for resonator filters of arbitrary topology using an evolutionary hybrid method. This method consists of a Levenberg-Marquardt algorithm for a local optimizer and genetic algorithm for a global optimizer, respectively. Unlike the conventional hybrid method in which the local optimization is performed after finding appropriate initial values from global optimization, the local optimizer in the proposed method is used as a genetic-algorithm operator to prevent trapping in local minima of the cost function. This method can provide fast convergence and good accuracy to find the final solution from initial population generated by a random number and the known value for the filters with stringent requirements. In addition, multiple coupling matrices to meet the given requirement can be obtained from the initial population based on a random number. Resonator filters with asymmetric eight-pole configurations for single and dual passbands are synthesized using the current method for validation. Excellent agreement between the response computed from characteristic polynomials and the response computed from couplings is obtained from the proposed method.     

Single switch dual output DC-DC converter performance

The performance of the single-switch dual-output DC-DC converter is evaluated. This converter regulates two independent DC outputs supplied from a single DC voltage source using a power semiconductor switch. Two discrete proportional feedback control loops regulate the duration of on switching and off switching. The duty cycle of the switch controls one output voltage, supplied from a low-pass filter, while the switching frequency regulates the other output voltage, supplied from a higher-frequency bandpass filter. The control algorithm is implemented with an Intel 8096 microcontroller. The experimental data demonstrate the actual circuit performance and confirm the simulation results. Both experiments and simulation show that an increase in the load current on the 12 V output results in an increase in the duty cycle, whereas an increase in the load current on the 5 V output results in a change in the switching frequency. The experimental prototype demonstrates operation over a load current range from about 40% to 100% with a ±25% variation in the 24 V input. Full load currents are 12 A and 2.5 A on the 12 V and 5 V outputs, respectively. The switching frequency ranged from approximately 29 kHz to 264 kHz, and the duty cycle ranged from 0.35 to 0.72     

Diffraction Effects in Reflected Ultrasound Spectral Estimates

This paper explores the effect of diffraction on estimates of the spectra of signals reflected from interfaces located at a given range from the transducer. When an ultrasound pulse is transmitted into a medium, the power spectra of reflected signals vary as a function of range from the transducer. These spectral changes are caused by diffraction effects, due to the finite-sized aperture, and by the properties of the medium. When the properties of the medium are to be determined from the backscattered signals, the diffraction effects tend to mask these properties, especially in the near field. Estimates of the diffraction effects are determined by accurately estimating the reflected signal spectra at a set of ranges from the transducer. The observed signals are reflections from media that are composed of randomly distributed scatterers and have a linear-with-frequency attenuation. The two random media considered are the in vivo liver and a tissue-equivalent phantom. The results indicate that the diffraction effects produce a high-frequency enhancement in the reflected spectra which diminishes with range. Similar results are observed for the reflections from plane and randomly roughened surfaces located at the same ranges. Simulated results using a transducer model verify the plane surface results. The effect of diffraction is examined in the clinical problem of estimating the slope of the acoustic attenuation coefficient of the in vivo liver. Diffraction introduces a bias into the observed slope estimate. The bias is a function of the range interval over which the reflected data are acquired.     

Antitumor effectiveness of chalone-like proteoglycans isolated from normal and tumor tissues

Chalone-like proteoglycans (PG) have been isolated from 22a hepatoma, spontaneous adenocarcinoma of the mammary gland of C3H/He mice and from transplanted X-ray-induced lymphoma in C57Bl mice. It has been found that the biological activity of these PG was considerably weaker than that of PG taken from the liver, mammary gland and spleen of cattle. PG from 22a hepatoma produced a weaker tissue-specific antimitotic effect as against PG from the liver when acting on the liver cells of 6-day C57Bl mice, while the lymphoma PG under these conditions was ineffective. PG from the liver and mammary gland inhibited the growth of certain transplanted tumours in vitro. The lymphoma PG has stimulated the tumour growth.     

Angular and seasonal variation of spectral surface reflectanceratios: implications for the remote sensing of aerosol over land

We obtain valuable information on the angular and seasonal variability of surface reflectance using a hand-held spectrometer from a light aircraft. The data is used to test a procedure that allows us to estimate visible surface reflectance from the longer wavelength 2.1 μm channel (mid-IR). Estimating or avoiding surface reflectance in the visible is a vital first step in most algorithms that retrieve aerosol optical thickness over land targets. The data indicate that specular reflection found when viewing targets from the forward direction can severely corrupt the relationships between the visible and 2.1 μm reflectance that were derived from nadir data. There is a month by month variation in the ratios between the visible and the mid-IR, weakly correlated to the Normalized Difference Vegetation Index (NDVI). If specular reflection is not avoided, the errors resulting from estimating surface reflectance from the mid-IR exceed the acceptable limit of Δρ~0.01 in roughly 40% of the cases, using the current algorithm. This is reduced to 25% of the cases if specular reflection is avoided     

A method for determinism in short time series,and its application to stationary EEG

A novel method for detecting determinism in short time series is developed and applied to investigate determinism in stationary electroencephalogram (EEG) recordings. This method is based on the observation that the trajectory of a time series generated from a differentiable dynamical system behaves smoothly in an embedded state space. The angles between two successive tangent vectors in the trajectory reconstructed from the time series is calculated as a function of time. The irregularity of the angle variations obtained from the time series is estimated using second-order difference plots, and compared with that of the corresponding surrogate data. Using this method, we demonstrate that scalp EEG recordings from normal subjects do not exhibit a low-dimensional deterministic structure. This method can be useful for analyzing determinism in short time series, such as those from physiological recordings.     

Frequency-spread associated with fast electronic scanning

It is shown that at fast scanning speeds the radar antenna beam contains frequency components other than the transmitted frequency, resulting in a frequency spread in the echo from a fixed target which is distinct from that arising from finite time on target.     

Separating core and noncore knowledge: an application of neural network rule extraction to a cross-national study of brand image perception

Recent advances in algorithms that extract rules from artificial neural networks make it feasible to use neural networks as a tool for acquiring knowledge hidden in the data. Findings are reported from the use of such algorithms to separate core and noncore knowledge in a cross-national study of automobile brand image perception. Respondents from five Western European countries have been asked to associate individual and corporate brand associations for a number of well-known automobile brands. Knowledge, expressed as concise and accurate rules that distinguish between the respondents' perceptions of German and Japanese brands, is extracted from trained neural networks. This paper explains how both core knowledge, which captures the perceptions shared by the respondents in all countries, and country-specific noncore knowledge can be acquired and differentiated by a proposed two-step approach to train and extract rules from a multi-neural network system. The experimental results show that, in addition to providing a better understanding of the differences and similarities in the brand image perceptions of consumers in various countries, the proposed approach also yields better predictive accuracy than a decision tree method.