DSpace Repository :: Browsing by Author "Neggers, Joseph"

Browsing by Author "Neggers, Joseph"

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Algorithms with applications in robotics
(University of Alabama Libraries, 2009) Munteanu, Bogdan; Borie, Richard B.; University of Alabama Tuscaloosa
Many real world applications which involve computational steps are closely tied to theoretical computer science. In order for these systems to be efficiently deployed and used, a thorough analysis is required in advance. This dissertation deals with several real world problems related to the field of Robotics, which can be mathematically modeled and analyzed. One of these problems is known as the pursuit evasion problem and involves the use of independent automated robots to capture a fugitive hiding in a building or a cave system. This is an extensively studied game theory and combinatorics problem which has multiple variations. It can be modeled as a graph and the goal is to minimize the cost of capturing the evader. We deal with two completely different variations of this problem: a vision based variant, in which the robots have limited vision and thus can react when the fugitive is in line of sight; and a no-vision variant, in which the robots do not have any knowledge about the fugitive. Another problem we deal with is the problem of neighbor discovery in wireless networks using directional antennas. This is another problem which received a growing interest in the last years. Our approach to solving this problem, as well as the model, is different from the other results that have been previously published in the literature. Besides modeling and formally analyzing these problems, our focus in this dissertation is to design efficient algorithms that solve them either completely or partially.
Capping the variance of cash flow of hedging strategy
(University of Alabama Libraries, 2011) Ginting, Maydison; Wu, Zhijian; University of Alabama Tuscaloosa
This dissertation consolidates previous research on an optimal strategy to reduce the running risk in hedging a long-term supply commitment with short-dated futures contracts. By introducing a cap function, this dissertation defines scenarios of running risk over the hedging horizon. We introduce a linear cap function and wish to find a hedging strategy G with the smallest constant F such that the variance of the cumulative cash flow is less than or equal the multiplication of a cap function and the constant F. The objective is to seek the best function G(s) to cap the variance of cash flow under a given non-negative cap function. We also implement the result in MATLAB by creating a Graphical User Interface application that enables the user to see the various results of the variance of cash flow of the best hedging scenario.
Design of a custom ASIC incorporating CAN^TM and 1-Wire® communication protocols
(University of Alabama Libraries, 2012) McNees, Michael Alan; Ricks, Kenneth G.; University of Alabama Tuscaloosa
The vast majority of today's digital designs utilize custom ASICs (Application-Specific Integrated Circuits) or gate arrays. In general, ASICs offer the lowest possible device power consumption for implementing a given function. Each year the number of custom ASICs designed increases, while the number of parts required for each design decreases. This is due in part to the increasing use of FPGAs (Field Programmable Gate Arrays) and their ability to provide a lower cost ASIC-based alternative for limited production designs. This paper presents a VLSI (Very Large Scale Integration) design and simulation of a custom ASIC incorporating two serial bus communication protocols, CAN^TM (Controller Area Network) and 1 - Wire®, and is targeted towards wearable medical technology and devices as well as advanced vehicular technologies. In designing a custom communications interface module, a number of technical and potentially challenging problems had to be addressed and overcome. These include but are not limited to: combining a multimaster and a single-master protocol, event-triggered and time-triggered control paradigms, differential communication speeds, and messages by addressing and messages by IDs. By combining the low-cost and ease of CAN^TM -enabling almost any device with the variety of 1 - Wire® devices currently in-production, the combinations of sensor networks is only limited by the creativity of the system designer. Given the limited FPGA resources utilized by the design presented in this manuscript, a low-cost ASIC could handle the data demands and provide the communications interface of most any application for either market.
Fibonacci sequences in groupoids
(Springer, 2012) Han, Jeong Soon; Kim, Hee Sik; Neggers, Joseph; Hanyang University; University of Alabama Tuscaloosa
In this article, we consider several properties of Fibonacci sequences in arbitrary groupoids (i.e., binary systems). Such sequences can be defined in a left-hand way and a right-hand way. Thus, it becomes a question of interest to decide when these two ways are equivalent, i.e., when they produce the same sequence for the same inputs. The problem has a simple solution when the groupoid is flexible. The Fibonacci sequences for several groupoids and for the class of groups as special cases are also discussed. 2000 Mathematics Subject Classification: 20N02; 11B39.
A graph theoretical model for the analysis of the game of football and a discussion of applications thereof
(University of Alabama Libraries, 2009) Taylor, Patrick; Neggers, Joseph; University of Alabama Tuscaloosa
In this dissertation an epidemiological approach is used to develop a graph theoretical model for the game of football. This model is a preliminary model due to the limitation of available resources. Even in its preliminary form, it is evident that significant information is obtained and easily displayed using graphs and adjacency matrices. A similar approach may be used in other game-like situations where coaches (manipulators) make decisions about strategy and tactics in order to prevail over opponents. In our case, the goal is to create a package of tools for the working professional in the field, i.e., the football coach and his assistants. As a study, this paper discusses its construction and methods, including procedures used to collect the data, analysis of the data, conclusions drawn, and commentary on future designs.
The hidden subgroup problem for generalized quaternions
(University of Alabama Libraries, 2009) Upton, Julia Tumasova; Corson, Jon M.; University of Alabama Tuscaloosa
The hidden subgroup problem is a pivotal problem in quantum computation since it reflects the structure of tasks for which quantum algorithms significantly outperform classical algorithms. In this dissertation, a quantum algorithm that solves the hidden subgroup problem over the generalized quaternion group is developed. The algorithm employs the abelian quantum Fourier transform and Kuperberg sieve to reveal the hidden subgroup.
Interval method for special constrained global optimization problems
(University of Alabama Libraries, 2014) Ying, Mengyi; Sun, Min; University of Alabama Tuscaloosa
The basic framework in this thesis is the standard Hansen method. The standard Hansen method has become a very well-known and popular method over the last few decades in the area of Interval Arithmetic [1] for finding all solutions of optimization problem. Listed below are some strategies we have developed: a). Binary tree data structure is proposed to record all the data associated with a functional relationship. We build a tree with the nodes representing all the operations and variables based upon the given function. Then we use a backward propagation method to obtain a new subdivision direction to be bisect. This method could accelerate the convergence after choosing the dominant variable in the tree data structure. Numerical results are illustrated to show the effectiveness in Chapter 3. b). Affine arithmetic is proposed to reduce the approximations' error and can be applied to linearize the given function and also applied in dealing with linear constraints. The main use of AA is to keep track of rounding errors for each computed value. Besides, AA provides a much tighter bound. Numerical results are illustrated to show the effectiveness in Chapter 3. c). Exclusion zone functions are introduced to further reduce variables' intervals which can be added in the deletion step in the standard Hansen algorithm. Numerical results are illustrated to show the effectiveness in Chapter 3. d). For constrained global optimization problems with one linear constraint, we have developed a backward interval value detection method as noted in Chapter 4. e). The four activities outlined above were performed to support this final activity. Three different procedures are developed (coordinate descent method, cutting line method, and projection coordinate descent method) to locate a feasible sampling point for the two linear constraints. Numerical results are illustrated to show the effectiveness in Chapter 5. The three procedures referenced above are then combined with the Interval Arithmetic method [1] to compare against the standard Hansen method without using any proposed strategies. The results of all three procedures in combination with the Interval Arithmetic method [1] are found to be superior to the standard Hansen technique.
Linear and nonlinear Rayleigh-Bénard convection in the absence of horizontal boundaries
(University of Alabama Libraries, 2014) Shahmurov, Rishad; Hadji, Layachi; University of Alabama Tuscaloosa
In the first part of the thesis, we will investigate the linear and weakly non- linear solutions to a convection problem that was first studied by Ostroumov in 1947. The problem pertains to the stability of the equations governing convective motion in an infinite vertical fluid layer that is heated from below. Ostroumov's linear stability analysis yields instability threshold conditions that are characterized by zero wave number for the Fourier mode in the vertical direction and by eigenfunctions that are independent of the vertical coordinate. Thus, any undertaking at determining the super critical nonlinear solutions and their stability through a small amplitude expansion fails. This failure is due to the fact that the terms induced by the nonlinear interaction of the linear modes vanish identically. Here, we put forth exact and stable solutions to the Ostroumov problem. These solutions are characterized by the same critical conditions for linear instability as the Ostroumov solutions. Moreover, we are able to use a small amplitude analysis to extend the analysis to the super critical regime and obtain the nonlinear steady stable solutions. Furthermore, when the analysis is extended to the case where the fluid layer thickness is also allowed to be infinite, we found that the infinite fluid region becomes linearly unstable through a Batchelor-Nitsche instability mechanism. The nonlinear solutions as well as similarity type solutions are then provided. Finally, numerical solutions of the full nonlinear problem are also presented which shed light on the flow patterns and temperature distribution induced by these new solutions. In the second part we consider Rayleigh-Bénard convection with a static density distribution whose unstably stratifed part occupies a very thin central layer. We get asymptotic relations for the critical Rayleigh number for small and large values of the thickness control parameter. Some limiting cases corresponding to the linear eigenvalue problem are treated analytically and the results confirmed by a detailed numerical investigation. For the moderate values of the thickness control parameter an analytical nonlinear stability three-dimensional study is under- taken in the case of poorly conducting boundaries. A weakly nonlinear evolution equation for the leading order temperature perturbation is also derived and solved numerically as function of thickness control parameter " and Prandtl number.
Matched interface and boundary enhanced multiresolution time-domain algorithm for electromagnetic simulations
(University of Alabama Libraries, 2011) Yao, Pengfei; Zhao, Shan; University of Alabama Tuscaloosa
The present work introduces a new boundary closure treatment for the wavelet based multiresolution time-domain (MRTD) solution of Maxwell's equations [1]. Accommodating nontrivial boundary conditions, such as the Robin condition or time dependent condition, has been a challenging issue in the MRTD analysis of wave scattering, radiation, and propagation. A matched interface and boundary multiresolution time-domain (MIBMRTD) method is introduced to overcome this difficulty. Several numerical benchmark tests are carried out to valid the MIB-MRTD method. Dispersion and stability analysis for the MIB-MRTD method are conducted and compared with the high-order finite difference time-domain (FDTD) method . The proposed boundary treatment can also be applied to other high order approaches, such as the dispersion-relation-preserving (DRP) method. The MIB boundary scheme greatly enhances the feasibility for applying the MRTD methods to more complicated electromagnetic structures.
Miniature hexaferrite axial-mode helical antenna for unmanned aerical vehicle applications
(University of Alabama Libraries, 2013) Neveu, Nicholas James; Hong, Yang-Ki; University of Alabama Tuscaloosa
Hexaferrite, axial-mode helical antenna is proposed to provide reliable communication for unmanned aerial vehicle (UAV) applications. The conventional axial-mode helical antenna uses an air core or low dielectric material, resulting in large antenna size. To increase the miniaturization factor, a Co2Z hexaferrite-glass composite was used as an antenna core. The material properties of ferrite and antenna design were studied to yield the best antenna performance. Axial-mode helical antennas were designed and simulated as well as experimentally fabricated. The 3-dimensional finite element method (FEM) simulation was performed to design a hexaferrite helical antenna and confirm the axial-mode operation at 2.44 GHz with gain of 2.0 dBi. The designed hexaferrite helical antenna showed 82% volume reduction and good impedance matching compared to the air-core antenna. The axial-mode hexaferrite antenna was fabricated based on the designed structure and characterized in an anechoic chamber. The maximum gain of 0.541 dBi was measured with a pitch angle of 10° at 2.39 GHz. Finally, a two-element axial-mode antenna array was designed based on the miniature hexaferrite antenna to further improve antenna gain. Maximum gain of 4.5 dBi at 2.43 GHz was simulated for the antenna array. Therefore, high gain and a miniature antenna can be achieved with the combination of Co2Z hexaferrite-glass composite and antenna design technology.
On Fibonacci functions with Fibonacci numbers
(Springer, 2012) Han, Jeong Soon; Kim, Hee Sik; Neggers, Joseph; Hanyang University; University of Alabama Tuscaloosa
In this paper we consider Fibonacci functions on the real numbers R, i.e., functions f : R -> R such that for all x is an element of R, f(x + 2) = f(x + 1) + f(x). We develop the notion of Fibonacci functions using the concept of f f-even and f-odd functions. Moreover, we show that if f is a Fibonacci function then lim(x ->infinity) f(x+1)/f(x) = 1+root 5/2.
On Fibonacci functions with periodicity
(Springer, 2012) Kim, Hee Sik; Neggers, Joseph; So, Keum Sook; Hanyang University; University of Alabama Tuscaloosa; Hallym University
In this paper we discuss Fibonacci functions using the (ultimately) periodicity and we also discuss the exponential Fibonacci functions. Especially, given a non-negative real-valued function, we obtain several exponential Fibonacci functions.
On labeled paths
(University of Alabama Libraries, 2010) Wiegand, Nathan; Borie, Richard B.; University of Alabama Tuscaloosa
Labeled graph theory is the marriage of two common problem domains to computer science -- graph theory and automata theory. Though each has been independently studied in depth, there has been little investigation of their intersection, the labeled paths. This dissertation examines three results in the area of labeled path problems. The first result presents an empirical analysis of two context-free labeled all-pairs shortest-path algorithms using MapReduce as the experimental platform. The second and third results examine labeled paths in the context of formal languages beyond the context-free languages. The second result is a lower bound on the length of the longest shortest path when the formal language constraining the path is a member of the control language hierarchy. Finally, the third result presents a labeled all-pairs shortest-path algorithm for each level of the infinite K Linear-Hierarchy.
ON Q-ALGEBRAS
(Wiley, 2001) Neggers, Joseph; Ahn, Sun Shin; Kim, Hee Sik
We introduce a new notion, called a Q-algebra, which is a generalization of the idea of BCH /BCI /BCK -algebras and we generalize some theorems discussed in BCI -algebras. Moreover, we introduce the notion of “quadratic” Q-algebra, and show that every quadratic Q-algebra (X; ∗, e), e ∈ X, has a product of the form x ∗ y = x − y + e, where x, y ∈ X when X is a ﬁeld with |X| ≥ 3. 2000 Mathematics Subject Classiﬁcation. 06F35, 03G25.
P-algebras and Q-algebras
(University of Alabama Libraries, 2010) Mahawanniarachchi, Padmal Sathyajith; Neggers, Joseph; University of Alabama Tuscaloosa
We define two classes of algebras P- and Q-, which are derived from the definitions of BCK- and BCI- algebras. The birth of P-algebras is based on the symmetric difference in set theory. We prove that the class of P-algebras is a variety, and the definition of P-algebras is an alternative definition for groups of exponent 2, which we call P-groups. The class of Q-algebras consists of a combination of three axioms of BCK- and P- algebras. We study the relationship among P-, Q- and BCI- algebras. The theory of P- and Q- algebras is developed parallel to the theory of BCK- and BCI- algebras.
A study of Federico Mompou's Variations sur un thème de Chopin
(University of Alabama Libraries, 2010) York, Sallye Jeffcoat; Penick, Amanda W.; University of Alabama Tuscaloosa
Federico Mompou (1893 - 1987) was a Catalan composer often compared to Satie, Debussy, and Ravel, composing mainly for solo piano and voice. His piano works have become a favorite in the teaching repertoire as well as the performance repertoire. Concert pianists such as Alicia De Laroccha and Stephen Hough have performed and recorded Mompou's compositions. Variations sur un thème de Chopin, one of Mompou's larger piano works, has become a standard piece for performance. It is an extensive work for solo piano based on Chopin's Prelude in A Major, Op. 28 No. 7. This document provides a study of Mompou's Variations sur un thème de Chopin, focusing on his adaptation of Chopin's motives, harmonies, and stylistic characteristics; influences from other composers are also considered where pertinent. Several books and dissertations include analyses of various Mompou compositions; however, none have sufficiently covered the large work Variations sur un thème de Chopin. This study provides an investigation of an important Mompou piece and contributes to the continuing scholarly research of this Catalan composer and his compositions.
Three assets model for portfolio selection under a constrained consumption rate process
(University of Alabama Libraries, 2009) Thagunna, Karan Singh; Wu, Zhijian; University of Alabama Tuscaloosa
[NOTE: Text or symbols not renderable in plain text are indicated by [...]. See PDF document for full abstract.] In this dissertation, we consider a particular case of an optimal consumption and portfolio selection problem for an infinitely lived investor whose consumption rate process is subject to downside constraint. We also suppose that the wealth dynamics is composed of three assets (i) risklessassets (ii) risky assets (iii) hedge assets. We consider the investor's wealth process, interpreted in the sense of the Itô integral as [...]. Our work aims to find the optimal policies which maximize the expected discount utility function given by [...]. Furthermore, we obtain the optimal policies in an explicit form for the log utility function which is a special case (γ → 1) of the general utility(CRRA) function, using the martingale method and applying the Legendre transform formula and the Feynman-kac formula. We derive some numerical results for the optimal policies and illustrated graphically.
Volatility analysis for high frequency financial data
(University of Alabama Libraries, 2009) Zheng, Xiaohua; Wu, Zhijian; University of Alabama Tuscaloosa
Measuring and modeling financial volatility are key steps for derivative pricing and risk management. In financial markets, there are two kinds of data: low-frequency financial data and high-frequency financial data. Most research has been done based on low-frequency data. In this dissertation we focus on high-frequency data. In theory, the sum of squares of log returns sampled at high frequency estimates their variance. For log price data following a diffusion process without noise, the realized volatility converges to its quadratic variation. When log price data contain market microstructure noise, the realized volatility explodes as the sampling interval converges to 0. In this dissertation, we generalize the fundamental Ito isometry and analyze the speed with which stochastic processes approach to their quadratic variations. We determine the difference between realized volatility and quadratic variation under mean square constraints for Brownian motion and general case. We improve the estimation for quadratic variation. The estimators found by us converge to quadratic variation at a higher rate.

Browsing by Author "Neggers, Joseph"

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