Engineering Commons^™

Space-Time Codes Concatenated With Turbo Codes Over Fading Channels, Junghoon Suh

Doctoral Dissertations

The uses of space-time code (STC) and iterative processing have enabled robust communications over fading channels at previously unachievable signal-to-noise ratios. Maintaining desired transmission rate while improving the diversity from STC is challenging, and the performance of the STC suffers considerably due to lack of channel state information (CSI). This dissertation research addresses issues of considerable importance in the design of STC with emphasis on efficient concatenation of channel coding and STC with theoretical bound derivation of the proposed schemes, iterative space-time trellis coding (STTC), and differential space-time codes.

First, we concatenate space-time block code (STBC) with turbo code for …

Application Of Polymer Rheology In Melt Blowing Process And Online Rheological Sensor, Yizhong Wang

Doctoral Dissertations

Polymer rheology plays a significant role in many polymer-processing operations such as polymer extrusion, fiber spinning, and nonwovens processing. To develop real time, online process and quality control system in these operations, knowledge of polymer rheology and how the rheological properties can be determined is crucial.

In this work, rheological properties of two melt blowing grades polypropylene (PP) under different processing conditions were determined by various off line methods, which includes dynamic rheological properties, shear and elongational viscosities. The elongational viscosity was measured at different Hencky strain by using semi-hyperbolic dies developed in this research group. Good master curves were …

Automated Exploration Of The Asic Design Space For Minimum Power-Delay-Area Product At The Register Transfer Level, Fuat Karakaya

Doctoral Dissertations

Exploring the integrated circuit design space for minimum power-delay-area (PDA) product can be time-consuming and tedious, especially when the target standard-cell library has hundreds of options. In this dissertation, heuristic algorithms that automate this process have been developed, implemented and validated at the reg- ister transfer level. In some cases, the PDA product was 1.9 times better than the initial baseline solution. The parallel search algorithm exhibited 9x speed up when executed on 10 machines simultaneously. These two new methods also characterize the design space for the given RTL code by generating power-delay-area points in addition to the minimum PDA …

Dynamic Left-Turn Phase Optimization Using Fuzzy Logic Control, Zhenyang Li

Doctoral Dissertations

The left-turn movement at an intersection has long been a concern of traffic engineers as it is a major capacity reduction factor. Different left-turn signal phasings have been shown to result in significant differences in delay, intersection capacity, and even safety level.

First, past studies about leading and lagging signal phases and signal control application are overviewed. Then this research gives a theoretical analysis of signal left-turn phase operations at both isolated and coordinated signalized intersections, compares the difference in delay based on leading and lagging left-turn signal phase designs, analyzes the influences of traffic control delay components for leading …

Integration Of Design Scales And Its Application To Multi-Component Adsorption Systems, Parag S. Adhangale

Doctoral Dissertations

Macroscopic simulations of chemical engineering unit processes provide a means of visualizing the relationship between different process variables through the use of constitutive equations such as the mass, energy and momentum balances. Molecular simulations on the other hand provide an insight into processes on the molecular scale. These simulations coupled with various concepts from statistical mechanics, are often used to study the properties of materials under a range of process conditions.

In a natural extension to these two fields, we use molecular simulations to obtain physico-chemical properties required for use in the macroscopic simulations of multi-component adsorption systems. The application …

Thermal Aging Effects On The Microstructure, Oxidation Behavior, And Mechanical Properties Of As-Cast Ni3Al Alloys, Dongyun Lee

Doctoral Dissertations

The thermal aging effects on the microstructure, oxidation behavior at 900⁰ and 1100⁰C, and mechanical properties of IC221M (Ni₃Al based intermetallic alloy, ASTM A1002-99) were investigated. The microstructure consists of dendritic arms of the [gamma] (nickel solid solution) phase containing cube-shape [gamma]ʹ (Ni₃Al) precipitates. The interdendritic regions are mostly [gamma]ʹ (Ni₃Al) with up to 8 vol.% [gamma] + Ni₅Zr eutectic constituents. Thermal aging effects on the microstructures and how microsegregation affects the oxidation behavior were examined. Four primary changes in the microstructures were observed: (1) there is considerable homogenization of the cast microstructures with aging, (2) the volume fraction of …

Silicon Based Micro Components For Use In Chemical Agent Detection, Scott R. Forrest

Doctoral Dissertations

The objective of this work was to model, fabricate and test silicon based micro components for applications in chemical agent detection. Part I deals with research done on tunable micro Fabry-Perot interferometers. These devices are designed for use in identifying chemicals that absorb radiation in the infrared range of the spectrum. Part II deals with research done on novel Layer by Layer (LbL) assembled enzyme microreactors. These devices are designed for use in identifying chemicals that absorb radiation in the ultraviolet and visible range of the spectrum.

The emphasis of Part I is on the design and modeling of Fabry-Perot …

Fatigue Of Drill Pipes Used In Horizontal Directional Drilling, Feibai Ma

Doctoral Dissertations

Fatigue is the most common cause of mini-HDD drill rod failure. It can occur at stress levels far below the normal operating stress in most drill stem components. Fatigue failures occur because the drill rod, after it has been forced into a curved path, undergoes a cyclic bending stress oscillating from tension to compression in concert with the other stress components caused by torque, thrust, or pullback.

When a rod breaks underground, there is considerable extra cost caused by the delay in “fishing” out the broken rod as well as the cost of replacing the rod. On the other hand, …

Fabrication, Characterization, And Chemical Sensing Of Silicon Dioxide Microcantilevers, Yanjun Tang

Doctoral Dissertations

The objective of this work is to design and fabricate an advanced silicon dioxide microcantilever sensor and to investigate chemical and biological sensing by microtechnology.

Microcantilever sensor technology has many advantages including fast response time, lower cost of fabrication, the possibility of sensor arrays with small overall dimensions, the ability to explore microenvironments, and improved portability for field applications. For all of these advantages, microcantilever chemical and biological sensors have drawn more and more attention.

So far, all other microcantilevers were designed and fabricated for AFM applications. We developed a novel SiO2 microcantilever especially for chemical and biological sensor applications. …