Engineering Commons^™

Application Of Neural Networks To Channel Assignment For Cellular Cdma Networks With Multiple Services And Mobile Base Stations, William S. Hortos

Electrical Engineering and Computer Science Faculty Publications

The use of artificial neural networks to the channel assignment problem for cellular code- division multiple access (CDMA) telecommunications systems is considered. CDMA takes advantage of voice activity and spatial isolation because its capacity is only interference limited, unlike time-division multiple access (TDMA) and frequency-division multiple access (FDMA) where capacities are bandwidth limited. Any reduction in interference in CDMA translates linearly into increased capacity. FDMA and TDMA use a frequency reuse pattern as a method to increase capacity, while CDMA reuses the same frequency for all cells and gains a reuse efficiency by means of orthogonal codes. The latter method …

Neural Network Architecture For Solving The Algebraic Matrix Riccati Equation, Fredric M. Ham, Emmanuel G. Collins

Electrical Engineering and Computer Science Faculty Publications

This paper presents a neurocomputing approach for solving the algebraic matrix Riccati equation. This approach is able to utilize a good initial condition to reduce the computation time in comparison to standard methods for solving the Riccati equation. The repeated solutions of closely related Riccati equations appears in homotopy algorithms to solve certain problems in fixed-architecture control. Hence, the new approach has the potential to significantly speed-up these algorithms. It also has potential applications in adaptive control. The structured neural network architecture is trained using error backpropagation based on a steepest-descent learning rule. An example is given which illustrates the …

Similarity-Based Learning For Pattern Classification, Laurene V. Fausett

Electrical Engineering and Computer Science Faculty Publications

Several standard neural networks, including counterpropagation networks, predictive ART networks, and radial basis function networks, are based on a combination of clustering (unsupervised learning) and mapping (supervised learning). A comparison of the characteristics of these networks for pattern classification problems is presented.

Partial Least-Squares Regression Neural Network (Plsnet) With Supervised Adaptive Modular Learning, Fredric M. Ham, Ivica Kostanic

Electrical Engineering and Computer Science Faculty Publications

We present in this paper an adaptive linear neural network architecture called PLSNET. This network is based on partial least-squares (PLS) regression. The architecture is a modular network with stages that are associated with the desired number of PLS factors that are to be retained. PLSNET actually consists of two separate but coupled architectures, PLSNET-C for PLS calibration, and PLSNET-P for prediction (or estimation). We show that PLSNET-C can be trained by supervised learning with three standard Hebbian learning rules that extracts the PLS weight loading vectors, the regression coefficients, and the loading vectors for the univariate output component case …

Determination Of Adaptively Adjusted Coefficients For Hopfield Neural Networks Utilizing The Energy Function, Chiyeon Park, Donald W. Fausett

Electrical Engineering and Computer Science Faculty Publications

With its potential for parallel computation and general applicability, the Hopfield neural network has been investigated and improved by many researchers in order to extend its usefulness to various combinatorial problems. In spite of its success in several applications within different energy function formulations, determination of the energy coefficients has been based primarily on trial and error methods since no practical and systematic way of finding good values has been available preciously, although some theoretical analyses have been presented. In this paper, we present a methodical procedure which adaptively determines the energy coefficients leading to a valid solution as the …

Efficient Buffer Allocation Scheme For Bursty Traffic In Atm Networks Using Fast Reservation Protocol, Nikhil Mukund Deshpande

Dissertations and Theses

One of the major problems in the realization of ATM is traffic management, in particular, the resource allocation for an efficient network. Many approaches to the bandwidth management problems [2] and buffer management problems have been proposed. Boyer [10] suggested a "Fast Bandwidth Reservation" protocol, while Turner [2] applied the same technique to the buffer allocation for the bursty traffic. In this thesis, we extend Turner's scheme in order to make it more efficient with respect to buffer allocation. We define a new parameter "Reduction Factor'', which has the potential of saving a significant amount of buffer space in a …

Calibration Of Spaceborne Scatterometers Using Tropical Rain Forests, David G. Long, Gary B. Skouson

Faculty Publications

Wind scatterometers are radar systems designed specifically to measure the normalized radar backscatter coefficient (O) of the ocean's surface in order to determine the near-surface wind vector. Postlaunch calibration of a wind scatterometer can be performed with an extended-area natural target such as the Amazon tropical rain forest. Rain forests exhibit a remarkably high degree of homogeneity in their radar response over a very large area though some spatial and temporal variability exist. The authors present a simple technique for calibrating scatterometer data using tropical rain forests, Using a polynomial model for the rolloff of O with incidence angle, the …

Studies Of Thin Strained Inas, Alas, And Alsb Layers By Spectroscopic Ellipsometry, C. M. Herzinger, Paul G. Snyder, F. G. Celii, Y.-C. Kao, D. Chow, B. Johs, John A. Woollam

Department of Electrical and Computer Engineering: Faculty Publications

The optical constants for thin layers of strained InAs, AlAs, and AlSb have been investigated by spectroscopic ellipsometry and multi-sample analyses. These materials are important for high-speed resonant tunneling diodes in the AlAs/InAs/In_0.53Ga_0.47As and AlSb/InAs material systems. Understanding the optical properties for these thin layers is important for developing in situ growth control using spectroscopic ellipsometry. Ex situ room-temperature measurements were made on multiple samples. The resulting fitted optical constants are interpreted as apparent values because they are dependent on the fit model and sample structure. These apparent optical constants for very thin layers can be …

A Crosstalk Correcting Router That Uses Online Noise Simulation To Route High-Speed Multichip Modules, Kenneth J. Mcclellan Jr.

Theses and Dissertations

Existing Multi Chip Module (MCM) auto-routers either ignore crosstalk or use over-simplified crosstalk approximations. Of the routers that do consider crosstalk, very few have the capability to correct crosstalk problems after they occur. This dissertation describes a router that not only has an internal crosstalk model for high speed MCMs which is more accurate than that of other existing routers, but also has the capability to use an online simulator to more accurately determine noise levels. After crosstalk problems occur, the router has the ability to correct these problems. Through memory usage reductions and routing efficiency improvements, this maze router …

Generalized Hidden Filter Markov Models Applied To Speaker Recognition, John M. Colombi

Theses and Dissertations

Classification of time series has wide Air Force, DoD and commercial interest, from automatic target recognition systems on munitions to recognition of speakers in diverse environments. The ability to effectively model the temporal information contained in a sequence is of paramount importance. Toward this goal, this research develops theoretical extensions to a class of stochastic models and demonstrates their effectiveness on the problem of text-independent (language constrained) speaker recognition. Specifically within the hidden Markov model architecture, additional constraints are implemented which better incorporate observation correlations and context, where standard approaches fail. Two methods of modeling correlations are developed, and their …

Text-Independent, Open-Set Speaker Recognition, Stephen V. Pellissier

Theses and Dissertations

Speaker recognition, like other biometric personal identification techniques, depends upon a person's intrinsic characteristics. A realistically viable system must be capable of dealing with the open-set task. This effort attacks the open-set task, identifying the best features to use, and proposes the use of a fuzzy classifier followed by hypothesis testing as a model for text-independent, open-set speaker recognition. Using the TIMIT corpus and Rome Laboratory's GREENFLAG tactical communications corpus, this thesis demonstrates that the proposed system succeeded in open-set speaker recognition. Considering the fact that extremely short utterances were used to train the system (compared to other closed-set speaker …

An Investigation Of Preliminary Feature Screening Using Signal-To-Noise Ratios, David B. Sumrell

Theses and Dissertations

A new saliency metric and a new saliency screening method are developed. This new metric, the SN saliency metric, is based upon signal-to-noise ratios, where the signal is provided by a sum of squared weights associated with a given feature, and the noise is based upon a sum of squared weights associated with a reference noise feature which is injected into the data. The resultant metric allows for a direct comparison of the feature of interest with a reference noise feature which is known to be nonsalient. The SN saliency screening method, which uses the SN saliency metric, offers the …

The Inhibition Of Amphipathic S- And N-Containing Compounds On Carbon Steel Corrosion, Wei Xing, Yibin Shan, Du Guo, Tianhog Lu, Shiquan Xi

Journal of Electrochemistry

Ordered monolayers of S- and N-containing amphipathic corrosion inhibitors were depoitod onto the surfaces of carbon steel electrode with super-molecular assembly technique. The effect of molecular aggregation of monolayers on carbon steel corrosion in 0.05 mol·cm^-3 H₂SO₄ and the mechanisms of these inhibitors were discussed in details. It was found that the transport of hydrated hydrogen ion to the surface of steel depends strongly on the inhibitor molecular aggregation in the monolayers.

The Influence Of Cathode Ingredients In Zinc Chloride Type Battery On The Discharge Ability, Qi Shen, Biao Zhuang

Journal of Electrochemistry

The influence of cathodic powder ingredients in ZnCl₂ type heavy duty battery on the discharge ability has been studied, a suitable battery ingredients is founds.

An Indirect Electrochemical Oxidation Of Toluene─Catalytic Effects Of Ag(Ⅰ) On Mn(Ⅱ)/Mn(Ⅲ) Couple Transition At Pt Electrode, Zhonghua Wang, Yunan Qu, Xingguo Yan, Qngmin Hua, Guacai Chen, Zhongquan Wang

Journal of Electrochemistry

The Catalytic effects of Ag(Ⅰ) on toluene oxidation by Mn(Ⅲ) as well as the anodic generation of Mn(Ⅲ) were investigated. The rates of toluene oxidation were first order with respect to both Ag(Ⅰ) and Mn(Ⅲ). Ag(Ⅱ) formed on the surface of the platinum anode when Ag(Ⅰ) was present in the anolyte, which catalyic the Mn(Ⅱ) to Mn(Ⅲ) in solution.

Study Of The Calcium-Thionyl Chloride Cells, Baohong Zhang, Meng Chen, Yingdong Wang, Dongsheng Xu

Journal of Electrochemistry

The properties of CaCl₂ SEI covered on the ca electrode surface in thionyl chloride, the influence of various salts in thionyl chloride on the porformance of the Ca anode and carbon cathode, and the function of the additive CuCl₂ and CuBr₂ to cathode in the improvement of the cathode performance were studied by AC impedance, constant current discharge, and SEM. As a result, the Ca-SOCl₂ cell was able to discharge at 50 mA·cm^-2 and the capacity reached 17.5 mAh·cm^-2.

Research On Molten Carbnate Fuel Cell, Naichao Li, Baolian Yi, Lianying Kong, Enjun Zhang, Huaxin Lin, Tianxi Qu, Yingcai Cheng

Journal of Electrochemistry

Cold-roll-milling has been evaluated as a technique for preparing porous LiAlO₂ matrices for use as a molten carbonate fuel cell electrolyte matrix. This technique produces reliable electrolyte structures with the following characteristics and advantages: ease of handling, uniform thickness, using nontoxic inorganic solvents, controlled pore size distribution, and ability to be impregnated with the alkali carbonate without fracrure.

The Molren Carbnatod Fuel Cell (MCFC) was assembled from sintered Ni electrodes and LiAlO₂ electrolyte matrix, the electrode area is 28 cm², the effect of operating conditions on cell performance was tested, it was found that the cell …

Nonlinearities In The Base Emitter Junction Of Heterojunction Bipolar Transistors, Oliver Woywode

Dissertations and Theses

The nonlinear behaviour of the base emitter junction in HBTs is investigated. Nonlinearities cause troublesome distortion and intermodulation of signals and raise the bit error rate. They are therefore a key issue in microwave communication systems. Hewlett-Packard's Microwave Design System (MDS) software package has been used to simulate these phenomena. The simulation results are verified by an analytical method called nonlinear current method which is a derivative of the Volterra series approach. With the aid of this method new analytical expressions are derived that provide insight into the subtleties of nonlinear phenomena. These expressions are evaluated by the program MAPLE …

The Discrete Laguerre Transform: Derivation And Applications, Giridhar Dhati Mandyam

Electrical and Computer Engineering ETDs

The discrete Laguerre transform (DLT) belongs to the family of unitary transforms known as Gauss-Jacobi transforms. Using classical methodology, the DLT is derived from the orthonormal set of Laguerre functions. Moreover, using recursion relationships common to all sets of orthonormal polynomials, generalized systolic arrays for forward and inverse unitary transform operations are derived and applied to the DLT. By examining the basis vectors of the transform matrix, the types of signals that can be best represented by the DLT are determined, namely oscillatory and damped oscillatory signals. Applications are demonstrated in the area of frequency domain adaptive filters, where the …

High-Temporal-Resolution, High-Sensitivity Imaging Of Streamers In A Long Atmospheric Pressure Gap, W. J. Yi, B. J. Hankla, P. F. Williams

P. F. (Paul Frazer) Williams Publications

We present time-resolved shutter photographs of streamers in a 13-cm gas-filled atmospheric pressure gap. The photographs show that in pure N₂, the streamers split readily in two. In mixtures containing O₂ , on the other hand, this bifurcation is substantially reduced.

Variable-Complexity Trellis Decoding Of Binary Convolutional Codes, David W. Matolak, S. G. Wilson

Faculty Publications

Considers trellis decoding of convolutional codes with selectable effort, as measured by decoder complexity. Decoding is described for single parent codes with a variety of complexities, with performance "near" that of the optimal fixed receiver complexity coding system. Effective free distance is examined. Criteria are proposed for ranking parent codes, and some codes found to be best according to the criteria are tabulated, Several codes with effective free distance better than the best code of comparable complexity were found. Asymptotic (high SNR) performance analysis and error propagation are discussed. Simulation results are also provided.

The Multirate Simulation Of Facts Devices In Power System Dynamics, J. G. Chen, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, the multirate method is applied to the problem of simulating the dynamics of a power system which contains fast components such as induction machine loads and FACTS devices. Results concerning the numerical stability and accuracy of the multirate method are presented. Implementation concerns are also addressed by studying an example power system which contains a wide range of time response behavior

Schlieren Photography Of Current Filaments In Surface-Related Breakdown Of Silicon, B. J. Hankla, P. F. Williams

P. F. (Paul Frazer) Williams Publications

We have used a modified Schlieren technique to photograph current filaments formed inside silicon during the very early stages of surface-related breakdown. We believe that the features we see are due to heating in the filamentary channel. The very rapid formation of these channels suggests that they result from streamer-like phenomena in the bulk silicon.

On The Adaptive Multi-Stage Detector For Cancellation Of Multiuser Interference In Cdma Wireless Communication Systems, Nadir Sezgin

Dissertations

The classical multiple access techniques such as Frequency Division Multiple Access (FDMA) and Time Division Multiple Access (TDMA) schemes are band limited in terms of their capacity to be used for mobile radio communication. Recent developments in the area of digital signal processing, makes Code Division Multiple Access (CDMA) as a possible solution to the demand of capacity for the mobile radio communication. The capacity of CDMA is limited by multiuser interference, that is the interference from the other users.

The goal of this dissertation is to improve the multiuser CDMA detector with high Bit Error Rate (BER) performance, low …

Adaptive Space-Time Processing For Wireless Communications, Xiao Cheng Bernstein

Dissertations

Adaptive space-time processing techniques have been found to increase the capacity of two major, multiple-access wireless communication systems: Time Division Multiple Access (TDMA) and Code Division Multiple Access (CDMA).

In an IS-54 TDMA system, the frequency re-use factor has to be set to 7 so that cells with the same spectrum are separated far enough to meet a required carrier-to-interference ratio (CIR). Space processing uses multiple antennas which, in turn, provide alternative signal paths in order to cancel interferences and combat multipath fading. We have proposed the eigencanceler method and have reviewed the theoretical optimum combining and the feasible direct …

On Optimal Design And Applications Of Linear Transforms, Mehmet V. Tazebay

Dissertations

Linear transforms are encountered in many fields of applied science and engineering. In the past, conventional block transforms provided acceptable answers to different practical problems. But now, under increasing competitive pressures, with the growing reservoir of theory and a corresponding development of computing facilities, a real demand has been created for methods that systematically improve performance. As a result the past two decades have seen the explosive growth of a class of linear transform theory known as multiresolution signal decomposition. The goal of this work is to design and apply these advanced signal processing techniques to several different problems.

The …

On The Optimization Problems In Multiaccess Communication Systems, Gangsheng Wang

Dissertations

In a communication system, the bandwidth is often a primary resource. In order to support concurrent access by numerous users in a network, this finite and expensive resource must be shared among many independent contending users. Multi-access protocols control this access of the resource among users to achieve its efficient utilization, satisfy connectivity requirements and resolve any conflict among the contending users. Many optimization problems arise in designing a multi-access protocol. Among these, there is a class of optimization problems known as NP-complete, and no polynomial algorithm can possibly solve them. Conventional methods may not be efficient arid often produce …

Comparison Of Adaptive Radar Algorithms : Transformed Smi, Eigencanceler, And Smi, Chaitanya H. Kathiari

Theses

Advanced airborne radars must perform target detection in the presence of interference and heavy clutter. In many applications, the practical usefulness of adaptive arrays is limited by their convergence rate. In this paper, we first analyze the performance of the SMI method. Then, two other methods, the transformed SMI and the eigencanceler, both based on the principle component inversion (PCI) technique, are described and analyzed by simulation. It is shown by simulation based comparison that the transformed SMI and the Eigencanceler outperform the SMI method. It is also shown that the transformed SMI and the eigencanceler has higher convergence rate …

Numerical Simulation Of Clipping Distortion In Lightwave Catv Systems, Luay Al-Nadi

Theses

Clipping induced distortion is an essential limit for modulation depth and number of channels in subcarrier multiplexed lightwave video transmission systems. Two different types of laser clipping are compared (single-clipping vs. double-clipping). In this work, the distortion limits imposed by clipping effects, in both directly (single-clipping) and externally (double-clipping) modulated systems, are examined. Numerical simulations were performed to test the efficiency of Saleh's Model. A comparison of results with clipping induced distortion in directly modulated lightwave systems (single-clipping) and clipping induced distortion in externally modulated lightwave systems (double-clipping) is presented, it is shown through numerical simulation that the total non-linear …

Analysis Of Calibration, Robustness, Detection Of Space-Time Adaptive Rada Using Experimental Data, Murat O. Berin

Theses

Signal cancellation effects in adaptive array radar are studied under non ideal conditions when there is a mismatch between the true desired signal and the presumed theoretical desired signal. This mismatch results in decreased performance when the estimated correlation matrix has a large desired signal component. The performance of the sample matrix inversion (SMI) method is compared to the eigenanalysis-based eigencanceler method. Both analytical results and the processing on the experimental data from the Mountaintop Program, show that eigenanalysis-based adaptive beamformers have greater robustness to signal cancellation effects than the SMI method. Also, the calibration of the recorded data, and …