Computer Engineering Commons^™

Robust And Resilient State Dependent Control Of Discrete-Time Nonlinear Systems With General Performance Criteria, Xin Wang, Edwin E. Yaz, Yvonne I. Yaz

Electrical and Computer Engineering Faculty Research and Publications

A novel state dependent control approach for discrete-time nonlinear systems with general performance criteria is presented. This controller is robust for unstructured model uncertainties, resilient against bounded feedback control gain perturbations in achieving optimality for general performance criteria to secure quadratic optimality with inherent asymptotic stability property together with quadratic dissipative type of disturbance reduction. For the system model, unstructured uncertainty description is assumed, which incorporates commonly used types of uncertainties, such as norm-bounded and positive real uncertainties as special cases. By solving a state dependent linear matrix inequality at each time step, sufficient condition for the control solution can …

A Companding Scheme With Enhanced Bit Error Rate For Peak-To-Average Power Ratio Reduction In Wireless Orthogonal Frequency Division Multiplexing Systems, Yasir Rahmatallah

Theses and Dissertations

Orthogonal Frequency Division Multiplexing (OFDM) is a popular multi-carrier modulation technique used in wireless communication systems due to its robustness against multipath fading. A major drawback inherited in OFDM is the non-constant envelope with high peak-to-average power ratio (PAPR). High PAPR drives the transmitter's power amplifier into saturation and causes nonlinear distortions. One way to avoid this is the use of companding to reduce the dynamic range of the time-domain OFDM signal. Usually, the PAPR is reduced at the cost of some degradation in bit error rate (BER) performance. A new scheme that utilizes traditional companding functions with side information …

Automation Of Orthodontic Wire Tester For Performing Three Point Bending Tests, Adithya Venkatesan

Master's Theses

Abstract

Understanding the biomechanical factors in orthodontics is important in order to improve the overall effectiveness of actual clinical treatment. An accurate method to study the threedimensional (3D) force systems and the resulting movements of teeth during orthodontic treatment is needed along with the understanding of the material properties of any orthodontic wire. Until recently, most of the orthodontic biomechanics literature was limited to twodimensional experimental studies. Recent advances in threedimensional computer modeling have also been developed but have been limited to the manual control of tooth movement. Overall, there is very little published evidence in the literature on the …

Software Development Approach For Discrete Simulators, Grzegorz Chmaj, Dawid Maksymilian Zydek

Electrical & Computer Engineering Faculty Research

Simulation is the most common approach to perform the problem research. Among several types of simulation, the most common way is the discrete simulation, which assumes the division of the time scale into fixed length time slots. Depending on investigated problem, simulation packages may be used or it could be necessary to design and create own simulation system. In this paper, we propose the complete pre-study scheme and the most commonly appearing implementation problems with suggested solutions. We also describe how to implement the exemplary simulator in C++.

Extracting Forensic Artifacts From Windows O/S Memory, James S. Okolica, Gilbert L. Peterson

AFIT Documents

Memory analysis is a rapidly growing area in both digital forensics and cyber situational awareness (SA). Memory provides the most accurate snapshot of what is occurring on a computer at a moment in time. By combining it with event and network logs as well as the files present on the filesystem, an analyst can re-create much of what has occurred and is occuring on a computer. The Compiled Memory Analysis Tool (CMAT) takes either a disk image of memory from a Windows operating system or an interface into a virtual machine running a Windows operating system and extracts forensic artifacts …

Efficient Geophysical Technique Of Vertical Line Elements As A Natural Consequence Of General Constraints Techniques, Rolando Cardenas, Martine Ceberio

Departmental Technical Reports (CS)

One of the main objectives of geophysics is to find how density d and other physical characteristics depend on a 3-D location (x,y,z). In general, in numerical methods, a way to find the dependence d(x,y,z) is to discretize the space, and to consider, as unknown, e.g., values d(x,y,z) on a 3-D rectangular grid. In this case, the desired density distribution is represented as a combination of point-wise density distributions. In geophysics, it turns out that a more efficient way to find the desired distribution is to represent it as a combination of thin vertical line elements that start at some …

Chaotic Bandgaps In Hybrid Acousto-Optic Feedback And Their Implications, Monish Ranjan Chatterjee, Mohammed A. Al-Saedi

Electrical and Computer Engineering Faculty Publications

The nonlinear dynamics of a hybrid acousto-optic device was examined from the perspective of the Lyapunov exponent (LE) and bifurcation maps. The plots for LE versus system parameters and bifurcation maps have recently been examined against known simulation results including chaotic encryption experiments [1]. It is verified that the "loop gain" (feedback gain (β) times incident light amplitude (Iin) needs to be greater than one as a necessary , but not sufficient condition for the onset of chaos.

It is found that for certain combinations of β, Iin, net bias voltage (αtοt), and the initial value of the first-order scattered …

Prediction In Econometrics: Towards Mathematical Justification Of Simple (And Successful) Heuristics, Vladik Kreinovich, Hung T. Nguyen, Songsak Sriboonchitta

Departmental Technical Reports (CS)

Many heuristic and semi-heuristic methods have been proposed to predict economic and financial processes. Some of these heuristic processes are intuitively reasonable, some seemingly contradict to our intuition. The success of these heuristics leads to a reasonable conjecture that these heuristic methods must have a more fundamental justification. In this paper, we provide such a justification for two simple (and successful) prediction heuristics: of an intuitive exponential smoothing that provides a reasonable prediction for slowly changing processes, and of a seemingly counter-intuitive idea of an increase in volatility as a predictor of trend reversal. As a possible application of these …

Reconstructing An Open Order From Its Closure, With Applications To Space-Time Physics And To Logic, Francisco Zapata, Vladik Kreinovich

Departmental Technical Reports (CS)

In his logical papers, Leo Esakia studied corresponding ordered topological spaces and order-preserving mappings. Similar spaces and mappings appear in many other application areas such the analysis of causality in space-time. It is known that under reasonable conditions, both the topology and the original order relation can be uniquely reconstructed if we know the "interior" < of the order relation. It is also known that in some cases, we can uniquely reconstruct < (and hence, topology) from the original order relation. In this paper, we show that, in general, under reasonable conditions, the open order < (and hence, the corresponding topology) can be uniquely determined from its closure.

The Cleanjava Language For Functional Program Verification, Yoonsik Cheon, Cesar Yeep, Melisa Vela

Departmental Technical Reports (CS)

Unlike Hoare-style program verification, functional program verification supports forward reasoning by viewing a program as a mathematical function from one program state to another and proving its correctness by essentially comparing two mathematical functions, the function computed by the program and its specification. Since it requires a minimal mathematical background and reflects the way that programmers reason about the correctness of a program informally, it can be taught and practiced effectively. However, there is no formal notation supporting the functional program verification. In this article, we describe a formal notation for writing functional program specifications for Java programs. The notation, …

High-Concentration Chemical Computing Techniques For Solving Hard-To-Solve Problems, And Their Relation To Numerical Optimization, Neural Computing, Reasoning Under Uncertainty, And Freedom Of Choice, Vladik Kreinovich, Olac Fuentes

Departmental Technical Reports (CS)

Chemical computing -- using chemical reactions to perform computations -- is a promising way to solve computationally intensive problems. Chemical computing is promising because it has the potential of using up to 10^{23} molecules as processors working in parallel -- and thus, has a potential of an enormous speedup. Unfortunately, for hard-to-solve (NP-complete) problems a natural chemical computing approach for solving them is exponentially slow. In this chapter, we show that the corresponding computations can become significantly faster if we use very-high-concentration chemical reactions, concentrations at which the usual equations of chemical kinetics no longer apply. We also show that …

All Kinds Of Behavior Are Possible In Chemical Kinetics: A Theorem And Its Potential Applications To Chemical Computing, Vladik Kreinovich

Departmental Technical Reports (CS)

Linear Neural Networks Revisited: From Pagerank To Family Happiness, Vladik Kreinovich

Departmental Technical Reports (CS)

The study of Artificial Neural Networks started with the analysis of linear neurons. It was then discovered that networks consisting only of linear neurons cannot describe non-linear phenomena. As a result, most currently used neural networks consist of non-linear neurons. In this paper, we show that in many cases, linear neurons can still be successfully applied. This idea is illustrated by two examples: the PageRank algorithm underlying the successful Google search engine and the analysis of family happiness.

Density-Based Fuzzy Clustering As A First Step To Learning The Rules: Challenges And Possible Solutions, Gözde Ulutagay, Vladik Kreinovich

Departmental Technical Reports (CS)

In many practical situations, it is necessary to cluster given situations, i.e., to divide them into groups so that situations within each group are similar to each other. This is how we humans usually make decisions: instead of taking into account all the tiny details of a situation, we classify the situation into one of the few groups, and then make a decision depending on the group containing a given situation. When we have many situations, we can describe the probability density of different situations. In terms of this density, clusters are connected sets with higher density separated by sets …

Measuring Robustness Of Feature Selection Techniques On Software Engineering Datasets, Huanjing Wang, Taghi Khoshgoftaar, Randall Wald

Computer Science Faculty Publications

Feature Selection is a process which identifies irrelevant and redundant features from a high-dimensional dataset (that is, a dataset with many features), and removes these before further analysis is performed. Recently, the robustness (e.g., stability) of feature selection techniques has been studied, to examine the sensitivity of these techniques to changes in their input data. In this study, we investigate the robustness of six commonly used feature selection techniques as the magnitude of change to the datasets and the size of the selected feature subsets are varied. All experiments were conducted on 16 datasets from three real-world software projects. The …

How To Encourage Imperfect Individuals To Care More About Society In General: A Utility-Theory Approach, Vladik Kreinovich

Departmental Technical Reports (CS)

A Simple Physics-Motivated Equivalent Reformulation Of P=Np That Makes This Equality (Slighty) More Plausible, Jaime Nava, Vladik Kreinovich

Departmental Technical Reports (CS)

In our opinion, one of the reasons why the problem P=NP? is so difficult is that while there are good intuitive arguments in favor of P=/=NP, there is a lack of intuitive arguments in favor of P=NP. In this paper, we provide such an argument -- based on the fact that in physics, many dependencies are scale-invariant, their expression does not change if we simply change the unit in which we measure the corresponding input quantity (e.g., replace meters by centimeters). It is reasonable to imagine similar behavior for time complexity t_A(n) of algorithms A: that the form …

How Accurately Should We Write On The Board? When Marking Comments On Student Papers?, Martine Ceberio, Olga Kosheleva

Departmental Technical Reports (CS)

Writing on the board is an important part of a lecture. Lecturers' handwriting is not always perfect. Usually, a lecturer can write slower and more legibly, this will increase understandability but slow down the lecture. In this paper, we analyze an optimal trade-off between speed and legibility.

I-Complexity And Discrete Derivative Of Logarithms: A Symmetry-Based Explanation, Vladik Kreinovich, Jaime Nava

Departmental Technical Reports (CS)

In many practical applications, it is useful to consider Kolmogorov complexity K(s) of a given string s, i.e., the shortest length of a program that generates this string. Since Kolmogorov complexity is, in general, not computable, it is necessary to use computable approximations K_~(s) to K(s). Usually, to describe such an approximations, we take a compression algorithm and use the length of the compressed string as K_~(s). This approximation, however, is not perfect: e.g., for most compression algorithms, adding a single bit to the string $s$ can drastically change the value K_~(s) -- while …

A New Justification For Weighted Average Aggregation In Fuzzy Techniques, Jaime Nava

Departmental Technical Reports (CS)

In many practical situations, we need to decide whether a given solution is good enough, based on the degrees a_i to which different criteria are satisfied. In this paper, we show that natural requirements lead to the weighted average decision, according to which a solution is acceptable if w₁ * a₁ + ... + w_n * a_n > t for some weights w_i and threshold t.