Engineering Commons^™

Modeling And Data Analysis Of Conductive Polymer Composite Sensors, Hua Lei

Theses and Dissertations

Conductive polymer composite sensors have shown great potential in identifying gaseous analytes. To more thoroughly understand the physical and chemical mechanism of this type of sensors, a model was developed by combining two sub-models: a conductivity model and a thermodynamic model, which gives a relationship between the vapor concentration of analyte(s) and the change of the sensor signals. In this work, 64 chemiresistors representing eight different carbon concentrations (8–60 vol.% carbon) were constructed by depositing thin films of a carbon black–polyisobutylene composite onto concentric spiral platinum electrodes on a silicon chip. The responses of the sensors were measured in dry …

Experimental And Modeling Investigations Of Biomass Particle Combustion, Hong Lu

Theses and Dissertations

This investigation provides a comprehensive analysis of entrained-flow biomass combustion processes. Experimental and theoretical investigations indicate how particle shape and size influence biomass combustion rates. Experimental samples include flake-like, cylinder-like, and equant (nearly spherical) shapes with similar particle masses and volumes but different surface areas. Samples of small (less than 500 µm) particles were passed through a laboratory entrained-flow reactor in a nitrogen/air atmosphere and a maximum reactor wall temperature of 1600 K, while large samples were reacted in suspension in a single particle furnace operated at similar conditions as the entrained-flow reactor. A separately developed computer and image analysis …

Characteristics And Engineering Properties Of The Soft Soil Layer In Highway Soil Subgrades, Tommy C. Hopkins, Tony L. Beckham, Liecheng Sun

Kentucky Transportation Center Research Report

The objective of this research was to examine the conditions and characteristics of soil subgrades that had been stabilized using mechanical compaction. Goals of the study are to identify and examine the engineering properties and behavior of the “soft layer’ of material observed at the top of untreated, highway pavement soil subgrades. Alternative methods of preventing, or mitigating, the development of the soft layer are discussed.

Evidence is presented that shows that a soft layer of soil frequently develops at the top of untreated, highway soil subgrades. Data are presented that show strengths obtained from mechanical compaction are largely destroyed …

Development Of A Gis Based Infrastructure Replacement Prioritization System; A Case Study, Brian D. Pickard

USF Tampa Graduate Theses and Dissertations

Maintenance, repair, and replacement of transmission mains and distribution system piping is expected to cost approximately $75 billion over the next two decades to ensure that public water systems are capable of providing the United States with safe drinking water. However, there is a significant gap between the funds available and the projected costs of infrastructure replacement or rehabilitation. Infrastructure Management Systems (IMS) have been developed to assist utilities and decision-makers in determining how to allocate resources for infrastructure. This project utilizes theTampa Water Department (TWD) as a case study to develop a tool for prioritizing infrastructure replacement.

TWD is …

Dynamic Modeling Of Microclimate And Environmental Control Strategies In A Greenhouse Coupled With A Heat Pump System, Ilhami Yildiz, D. P. Stombaugh

BioResource and Agricultural Engineering

The purpose of this study was to develop and validate a dynamic simulation model to be employed in accurate prediction of microclimate in a greenhouse as a function of dynamic environmental factors. The model has options to evaluate the effects of location, time of the year, orientation, single and double polyethylene glazings, conventional and heat pump heating and cooling systems, open and confined greenhouse systems, CO₂ enrichment, variable shading, and the use of night curtains. Conventional gas furnace and evaporative cooling, respectively, provided heating and cooling in the conventional system. In the heat pump systems, gas-fired heat pump units …

Discrete Cosine Transform Based Shift Estimation For Fringe Pattern Profilometry Using Generalized Analysis Model, Jose F. Chicharo, Jiangtao Xi, Yingsong Hu, Zongkai Yang, Enbang Li

Faculty of Engineering - Papers (Archive)

This paper presents a new analysis algorithm to carry out profile measure- ment with low computational complexity and less noise-sensitivity. Firstly, a discrete cosine transform (DCT) based representation method is introduced to express the height distribution of the three-dimensional surface. Then, a novel shift estimation algorithm, called DCT based shift estimation (DCT-SE) is presented to reconstruct three-dimensional object surfaces by using the proposed expression and the generalized analysis model. The advantage of DCT-SE is that without loss of measurement precise it provides lower computational complexity to implement three-dimensional reconstruction from distorted fringe patterns and at the same time survives from …

A Microslip Model Of The Bonding Process In Ultrasonic Wire Bonders Part I: Transient Response, C M. Hu, N Guo, H Du, W H. Li, M Chen

Faculty of Engineering - Papers (Archive)

Ultrasonic wire bonders with precision capillary tips are widely used for bonding electrical wires to IC chips and circuits. The industry is driving wire-bonding technology towards increased yields, decreased pitch, and ever decreasing cost. However, many technical and material issues will be involved in achieving these goals, such as bond quality monitoring, new failure modes, reliability problems in new plastic mold compounds, and increasing wire sweep problems, in particular lack of the quantitative understanding and validated mathematical model of the bonding process. In this paper, a microslip model is proposed for the bonding process based on the bonding pattern observed, …

Dynamic Model Simplification Of Serial Manipulators, Subir Kumar Saha, Bijan Shirinzadeh, Gursel Alici

Faculty of Engineering - Papers (Archive)

Simplicity in the dynamics model of a serial robot manipulator greatly enhances the speed of its control and the associated hardware implementation. Since the motion of one link influences the torque or force required at the other joints, the control becomes difficult. This is referred as dynamic coupling. In this paper, it is proposed to simplify the robot's dynamic coupling by suitably choosing the manipulator’s kinematic and dynamic parameters. The intention is to make the Generalized Inertia Matrix (GIM) of the serial manipulator associated with its dynamic equations of motion diagonal and/or constant. Such choice automatically ensures the associated convective …

A New Model For Thermal Conductivity In Nanofluids, Pei Tillman, James M. Hill

Faculty of Engineering - Papers (Archive)

Nanofluids exhibit enhanced thermal conductivity superior to traditional heat transfer fluids. The conventional theoretical models cannot explain the large enhancement of the thermal conductivity of nanofluids. It has been proposed that an interfacial structure formed by liquid molecular layering might play an important role. To date there is no known procedure to properly calculate the nanolayer thickness, and all previous investigators arbitrarily adopt a layer thickness which is consistent with experimental results. Here we investigate the thermal conductivity structure of this interfacial layer and its impact on the effective thermal conductivity and an expression for the thermal conductivity profile in …

Use Of Polyhydroxyalkanoates For Denitrification In Recirculating Aquaculture Systems, Maria Teresa Gutierrez-Wing

LSU Doctoral Dissertations

Increasing demand of aquacultural products is driving the industry toward more intensive culture practices. Aquacultural operations are constrained by limitations on the availability high quality waters and regulatory pressures on the discharges. Recirculating systems can address these issues by reducing the amount of water required in the operation. Closed systems are especially suited where biosecurity is important. In closed systems, nitrate accumulates, limiting the time the water can be reused. In marine inland systems, water reuse reduces the cost of salt for make up water. To increase the water reuse time, some form of nitrate removal process must be incorporated …