Engineering Commons^™

A Modified Surface Energy Balance For Modeling Evapotranspiration And Canopy Resistance, Luis O. Lagos

Department of Agricultural and Biological Systems Engineering: Dissertations, Theses, and Student Research

A modified surface energy balance (SEB) model based on the Shuttleworth-Wallace and Choudhury-Monteith methods was developed to estimate evaporation from soil covered by crop residue, and transpiration from crop canopies. The model describes the energy balance and flux resistances for partially-vegetated and residue-covered surfaces. Physical and biochemical energy storage terms and lateral fluxes are neglected in the model. Net radiation is one of the inputs in the SEB model and provides the energy needed for soil evaporation, crop transpiration and heat transfer through the canopy, soil/residue surfaces and the atmosphere.

A sensitivity analysis of the SEB model parameters showed that …

Development Of An Inexpensive, Haptic Graphical Display Device, David Burch

Theses and Dissertations

A finger-worn haptic device capable of rendering 2-D graphics through vibrotactile feedback is presented. The device development is presented from its initial stages of being a stylus design using a photo-interrupter optical sensor and pager-motor actuator to a small case worn on the finger using a RGB color sensor and a piezoelectric actuator. Testing of the latest prototype design shows that it has a spatial sensitivity (<2mm) comparable to natural touch (~1mm) and can be used to output a variety of vibrotactile textures. The design can be expanded for a multiple finger, independent device, while remaining affordable (<$100) and highly portable (<500g).

Automatic Generation Of Decomposition Based Matrix Inversion Architectures, Ali Irturk, Bridget Benson, Arash Arfaee, Ryan Kastner

Electrical Engineering

Matrix inversion is an essential computation for various algorithms which are employed in multi-antenna wireless communication systems. FPGAs are ideal platforms for wireless communication; however, the need for vast amounts of customization throughout the design process of a matrix inversion core can overwhelm the designer. Decomposition methods provide the analytic simplicity and computational convenience necessary for computationally intensive matrix inversion. This paper presents automatic generation of different decomposition based matrix inversion architectures using a matrix inversion core generator tool, GUSTO with different parameterization options. We present automatic generation of a variety of general purpose matrix inversion architectures which have comparable …

Nondestructive Evaluation Of Aircraft Composites Using Terahertz Time Domain Spectroscopy, Christopher D. Stoik

Theses and Dissertations

Terahertz (THz) time domain spectroscopy (TDS) was assessed as a nondestructive evaluation technique for aircraft composites. Material properties of glass fiber composite were measured using both transmission and reflection configuration. The interaction of THz with a glass fiber composite was then analyzed, including the effects of scattering, absorption, and the index of refraction, as well as effective medium approximations. THz TDS, in both transmission and reflection configuration, was used to study composite damage, including voids, delaminations, mechanical damage, and heat damage. Measurement of the material properties on samples with localized heat damage showed that burning did not change the refractive …

Dynamic Supersonic Base Store Ejection Simulation Using Beggar, Michael D. Johnson

Theses and Dissertations

Static and dynamic conditions throughout various aft supersonic store separation events are examined using the Beggar Computational Fluid Dynamics (CFD) code from Air Force SEEK Eagle Office at Eglin Air Force Base, FL. An 8.9 deg half angle sphere cone is used for the carrier vehicle with an identically shaped store stowed within a hollow compartment in the aft section of the carrier body. Dynamic store separation simulations are implemented at a free-stream Mach of 2.9 with a Reynolds number of Re = 6.9 x 10⁶/m referenced against carrier base diameter. Analysis covers multiple dynamic separation events along …

Investigation Of Heterogeneity Of Fsw Inconel 718 Coupled With Welding Thermal Cycle, Dong Fang Huang

Theses and Dissertations

In order to develop a better understanding of the property, microstructure evolution and thermal history of FSW Inconel 718's, the strain, strain rate and thermal cycles need to be determined. In order to estimate the strain field of a deformed body, a displacement function needs to be determined. A 3D deformation model was developed to determine the displacement coefficients. A rectangular box created in this model deforms following a linear displacement function. Three orthogonal planes cut this deformed box, which leads to three deformed planes. The shape parameters (L, H, θ¹ and θ²) on the three orthogonal planes can be …

Flexible Twist For Pitch Control In A High Altitude Long Endurance Aircraft With Nonlinear Response, Vanessa L. Bond

Theses and Dissertations

Information dominance is the key motivator for employing high-altitude long-endurance (HALE) aircraft to provide continuous coverage in the theaters of operation. A joined-wing configuration of such a craft gives the advantage of a platform for higher resolution sensors. Design challenges emerge with structural flexibility that arise from a long-endurance aircraft design. The goal was to demonstrate that scaling the nonlinear response of a full-scale finite element model of a high-altitude long-endurance (HALE) aircraft was possible if the model was aeroelastically and "nonlinearly" scaled. A straight-forward method of scaling the first three natural vibration frequencies and mode shapes, and the first …

Development Of High Performance Precast/Prestressed Bridge Girders, Amin K. Akhnoukh

Department of Construction Engineering and Management: Dissertations, Theses, and Student Research

Demand continues to increase for bridges with long spans and shallow depths. Due to safety concerns, four-span overpasses are being replaced with two span overpasses to avoid placement of piers near the highway shoulders. In the meantime, the bridge profile is restricted due to existing businesses nearby. Thus, nearly the same superstructure depth must be used for double the span length. This dissertation focuses on topics aiming at providing precast prestressed concrete girders with the shallowest possible depth for a given span. It forms parts of larger projects conducted by the University of Nebraska for the Nebraska Department of Roads …

Warm Hydroforming Characteristics Of Stainless Steel Sheet Metals, Eren Billur

Theses and Dissertations

For numerical modeling and predictive analysis of warm hydroforming, better understanding of material properties (i.e. Flow curves) is required at elevated temperatures and high strains. Hydraulic bulge testing is a suitable method to obtain this information. However, analysis of the test data is not standardized as there are numerous approaches developed and adopted throughout the years. In this study, first, different approaches for hydraulic bulge analysis were compared with stepwise experiments to determine the best combination of approaches in obtaining accurate flow curves at different temperatures and strain rates. Then, three different grades of stainless steels (AISI 201, 301 and …

Optical Hyperspace For Plasmons: Dyakonov States In Metamaterials, Zubin Jacob, Evgenii E. Narimanov

Birck and NCN Publications

We show that the subdiffraction imaging behavior observed in the magnifying superlens experiment, [Smolyaninov , Science 317, 1699 (2007)] is due to the hyperbolic dispersion of Dyakonov plasmons supported by the device. These states which are a special case of Dyakonov surface waves [Dyakonov, Sov. Phys. JETP 67, 714 (1988)] exist at the interface of a metal and an anisotropic dielectric giving rise to plasmon beams on resonance. Furthermore, we describe how the unique properties of metamaterial Dyakonov plasmons can be tailored for plasmonic devices.

Fingering Instabilities On Reaction Fronts In The Co Oxidation Reaction On Pt(100), D. Bilbao, Jochen A. Lauterbach

Faculty Publications

Fingering instabilities arising from local perturbations to planar reaction fronts in the CO oxidation reaction on Pt(100) are presented. CO oxidation represents a heterogeneous nonlinear system with the necessary kinetic and diffusive transport properties to support the development of fingered wave fronts. External forcing was utilized to create CO wave fronts on an otherwise monostable, O-covered surface, which, upon destabilization, gave rise to fingers of adsorbed CO extending into the O adlayer ahead of the reaction front. Finger spreading and tip-splitting were observed as the finger pattern evolved towards an intrinsic wavelength, independent of the length of the reaction front, …

The Effect Of Liquid Hot Filling Temperature On Blow-Molded Hdpe Bottle Properties, Benjamin S. Hudson

Theses and Dissertations

The occurrence of deformation in plastic bottles is a common problem in the bottling industry where bottles are blow molded, hot filled at high temperatures and sealed. Plastics have unique properties that make it difficult to predict when and why such changes may occur. The root cause of such deformation is unknown by many bottle producers and recent attempts have been made to minimize the occurrence of such defects. The purpose of this research is to determine which variables involved in the bottle production process influence bottle shape. Earlier variables that were tested included both blow molding resin and total …

College Of Engineering Senior Design Competition Fall 2008, University Of Nevada, Las Vegas

Fred and Harriet Cox Senior Design Competition Projects

Part of every UNLV engineering student’s academic experience, the senior design project stimulates engineering innovation and entrepreneurship. Each student in their senior year chooses, plans, designs, and prototypes a product in this required element of the curriculum. A capstone to the student’s educational career, the senior design project encourages the student to use everything learned in the engineering program to create a practical, real world solution to an engineering challenge.

The senior design competition helps to focus the senior students in increasing the quality and potential for commercial application for their design projects. Judges from local industry evaluate the projects …

Assessing Water Quality Modeling In Subtropical Regions Based On A Case Study Of The Aguamilpa Reservoir, Oliver Obregon

Theses and Dissertations

The shortage of water in Mexico has made public and private institutions look at reservoirs as an alternative solution for present and future water supply. However, eighty percent of the existing reservoirs in Mexico are contaminated at some level, many severely. Water quality models are water-management tools used to diagnose water quality problems and the impact of various environmental conditions. They can be effective in assessing various measures of remediation leading to improved water quality. In most of the cases such water quality models have been successfully applied in reservoirs located in temperate climates. However, the use of water quality …

Ceas E-News 12.02.2008, College Of Engineering And Applied Sciences

College of Engineering and Applied Sciences News

Five honored with 2008 CEAS Dean Awards for outstanding work

Multidimensional Modeling Of Solid Propellant Burning Rates And Aluminum Agglomeration And One-Dimensional Modeling Of Rdx/Gap And Ap/Htpb, Matthew Wilder Tanner

Theses and Dissertations

This document details original numerical studies performed by the author pertaining to solid propellant combustion. Detailed kinetic mechanisms have been utilized to model the combustion of the pseudo-propellants RDX/GAP and AP/HTPB. A particle packing model and a diffusion flame model have been utilized to develop a burning rate and an aluminum agglomeration model. The numerical model for RDX/GAP combustion utilizes a "universal" gas-phase kinetic mechanism previously applied to combustion models of several monopropellants and pseudo-propellants. The kinetic mechanism consists of 83 species and 530 reactions. Numerical results using this mechanism provide excellent agreement with RDX and GAP burning rate data, …

Detection Of An So2 Plume Over Sapporo, Japan From The Eruption Of Mt. Kasatochi Using A Balloon Sounding Technique, Gary A. Morris, Jun Hirokawa, Masatomo Fujiwara, Fumio Hasebe, Keisuke Ishida, Nicholay Krotkov, Mark R. Schoeberl, Walter Komhyr, Barry Lefer, James Flynn

Physics and Astronomy Faculty Presentations

During the month of August 2008, 10 ozonesondes were launched from Hokkaido University in Sapporo, Japan as part of a study to examine regional pollution during the Olympic period. Seven of these soundings included a second instrument with a filter designed to remove SO2 from the intake air stream. SO2 interferes with the normal chemistry of the electrochemical cell (ECC) method for ozone detection, with the net result being that each molecule of SO2 registers as minus one molecule of O3. Thus the unfiltered sonde reports [O3] - [SO2] while the filtered sonde reports [O3]. Laboratory tests prior to launch …

Acuta Enews December 2008, Vol. 37, No. 12

ACUTA Newsletters

In This Issue

From the President.............. Corinne Hoch, Columbia, Univ., ACUTA President

Board Report............. Riny Ledgerwood, San Diego State Univ., ACUTA Secretary/Treasurer

DC Update............. Dave Ostrom, Washington State Univ. (retired)

Info Links........... Randy Hayes, Univ. of Northern Iowa

ACUTA Guide to Products and Services: Keep It Handy, Use It Often

ACUTA Web Seminar: Wireless Andrew 2.0

"Earthbottle" Brought to you by Clemson

Check It Out: Press Releases... Job Postings.... RFIs/RFPs

Holiday Greetings from the ACUTA Staff

Welcome New Members

Secondary Electron Emission From Freely Supported Nanowires, Makoto Suzuki, Kazuhiro Kumagai, Takashi Sekiguchi, Alan M. Cassell, Tsutomu Saito, Cary Y. Yang

Electrical and Computer Engineering

We present secondary electron (SE) emission results from freely supported carbon/silicon nitride (Si₃N₄) hybrid nanowires using scanning electron microscopy. We found that, contrary to bulk materials, the SE emission from insulating or electrically isolated metallic nanowires is strongly suppressed by the penetrating beam. A mechanism of the SE suppression by the positive specimen charging is proposed, which is based on a total emission yield calculation using the Monte Carlo technique. This finding provides an important basis for studying low-energy electron emission from nanostructures under a penetrating electron beam.

Detection Of Voids In Prestressed Concrete Bridges Using Thermal Imaging And Ground-Penetrating Radar, David G. Pollock, Kenneth J. Dupuis, Benjamin Lacour, Karl R. Olsen

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

Thermal imaging and ground-penetrating radar was conducted on concrete specimens with simulated air voids. For the thermal imaging inspections, six concrete specimens were constructed during the month of June 2007 to simulate the walls of post-tensioned box girder bridges. The objective was to detect simulated air voids within grouted post-tensioning ducts, thus locating areas where the post-tensioning steel strands are vulnerable to corrosion. The most important deduction taken from these inspections was that PT-ducts and simulated voids were more detectable in the 20 cm (8 in.) thick specimens than in the 30 cm (12 in.) thick specimens. While inspections of …

Design, Fabrication, Modeling And Characterization Of Electrostatically-Actuated Silicon Membranes, Brian C. Stahl

Master's Theses

This thesis covers the design, fabrication, modeling and characterization of electrostatically actuated silicon membranes, with applications to microelectromechanical systems (MEMS). A microfabrication process was designed to realize thin membranes etched into a silicon wafer using a wet anisotropic etching process. These flexible membranes were bonded to a rigid counterelectrode using a photo-patterned gap layer. The membranes were actuated electrostatically by applying a voltage bias across the electrode gap formed by the membrane and the counterelectrode, causing the membrane to deflect towards the counterelectrode. This deflection was characterized for a range of actuating voltages and these results were compared to the …

Mapping Reality Into Virtual Worlds, Josh Mcfarlane

Computer Science and Computer Engineering Undergraduate Honors Theses

As virtual worlds become more prevalent, they become increasingly useful as a means of information dissemination. This thesis examines the possible connections between real world objects and their virtual world counterparts. We look at how, by attaching sensors to an object, or by using a smart object with embedded sensors, the information can be relayed to a server. From this information, it will be possible to create a duplicate object in the virtual world and have it mirror the real world object in terms of state and movement. Almost all current solutions for remotely viewing a room or area are …

Preparation And Characterization Of Particles From Chitosan With Different Molecular Weights And Their Trimethyl Chitosan Derivatives For Nasal Immunization, W Boonyo, H E. Junginger, N Waranuch, A Polnok, T Pitaksuteepong

Journal of Metals, Materials and Minerals

According to previous studies, molecular weights (MW) of chitosan presented an influence on the level of immune response to model antigen when administering with chitosan through nasal route. Moreover, trimethyl chitosan (TMC) with a degree of quaternization (DQ) of 40%, chitosan derivatives, was also shown to be the most potent nasal OVA delivery platforms compared to TMC with DQ of 20% and 60% in mice model. The aims of this study were to prepare particles from chitosan with difference MW and their TMC derivatives (DQ = 40%) and to characterize size, zeta potential, loading efficiency and release profile in order …

Chitosan/Calcium Phosphate Composites Scaffolds Prepared By Membrane Diffusion Process, P Thanaphat, P Thunyakitpisal, W Techaboonyakiat

Journal of Metals, Materials and Minerals

Hydroxyapatite (Ca10(PO4)6(OH)2, HAp) and Dicalcium phosphate dihydrate (CaHPO4.H2O, DCPD) were homogeneously hybridized into chitosan solution by membrane diffusion process. The threedimensional scaffolds were obtained by freeze-drying process. The organic and inorganic contents of scaffold were determined by using thermogravimetry analysis (TGA). The surface morphology of the scaffold and characteristic of calcium phosphate were investigated by scanning electron microscope (SEM), energy dispersive X-ray spectrometer (EDX), and X-ray diffraction (XRD), respectively. Compressive modulus was also determined by dynamic mechanical analysis (DMA). The hybridized inorganic content ranges from 35-45%. Both chitosan/HAp and chitosan/DCPD scaffolds showed interconnected porous structure. The calcium to phosphorus ratios …

Application Of Chitosan In Rice Production, S Boonlertnirun, C Boonraung, R Suvanasara

Journal of Metals, Materials and Minerals

Chitosan is a natural biopolymer which stimulates growth and increases yield of plants as well as induces the immune system of plants. The objectives of this study were to determine appropriate applications for increasing of the rice yield. The experiment was performed with randomized complete block design ( RCBD) with four replications. Four treatments were done as follows : no chitosan application, seed soaking with chitosan solution, seed soaking and soil application with chitosan solution and seed soaking and foliar spraying with chitosan solution. The results showed that application of chitosan by seed soaking and soil application four times throughout …

Estimating Risk Under Interval Uncertainty: Sequential And Parallel Algorithms, Vladik Kreinovich, Hung T. Nguyen, Songsak Sriboonchitta

Departmental Technical Reports (CS)

In traditional econometrics, the quality of an individual investment -- and of the investment portfolio -- is characterized by its expected return and its risk (variance). For an individual investment or portfolio, we can estimate the future expected return and a future risk by tracing the returns x₁, ..., x_n of this investment (and/or similar investments) over the past years, and computing the statistical characteristics based on these returns. The return (per unit investment) is defined as the selling of the corresponding financial instrument at the ends of, e.g., a one-year period, divided by the buying price …

Mathematical Justification Of Spectral/Covariance Techniques: On The Example Of Arc Detection, Jan Beck, David Nemir, Vladik Kreinovich

Departmental Technical Reports (CS)

Detecting arcing faults is an important but difficult-to-solve practical problem. Many existing methods of arc detection are based upon acquiring a signal that is proportional to current and then making an analysis of the signal's power spectrum (or, equivalently, its covariance function). Since the power spectrum, i.e., the absolute values of the Fourier transform, carries only partial information about the signal, a natural question is: why should we restrict ourselves to the use of this partial information? A related question is caused by the fact that even the most efficient methods still miss some arcing faults and/or lead to false …

Computing With Tensors: Potential Applications Of Physics-Motivated Mathematics To Computer Science, Martine Ceberio, Vladik Kreinovich

Departmental Technical Reports (CS)

In this paper, we explain what are tensors and how tensors can help in computing.

Hydro-Nexrad: An Updated Overview And Metadata Analysis, Witold F. Krajewski, Anton Kruger, Piotr Domaszczynski, Charles Gunyon, Bong Chul Seo, Radosław Goska, James A. Smith, Mary Lynn Beack, Matthias Steiner

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Hydro-NEXRAD is a prototype system that allows hydrologists to obtain user-specified rainfall data for their research. These data are based on observations collected by the national network of WSR-88D radars, known as NEXRAD. Users interact with Hydro-NEXRAD through a web-based interface that has map-based components for spatial navigation, calendar- and time series plot components for temporal navigation and a menu-based component for selection of processing options. Through the interface, users browse the Hydro-NEXRAD metadata and select data of interest. As the system is approaching the point of being fully operational, the authors and a group of test users have evaluated …

Fabrication Of Porous Bioactive Glass-Ceramics Via Decomposition Of Natural Fibres, P Sooksaen, S Suttiruengwong, K Oniem, K Ngamlamiad, J Atireklapwarodom

Journal of Metals, Materials and Minerals

Porous bio glass-ceramics were prepared via natural fibres burning-out process. Glass-ceramics were fabricated by controlled crystallization of suitable glass compositions to give required crystalline phase/s. Porous structure was formed alongside during burning-out of natural fibres. Three glass batches were prepared in the SiO2-CaO-P2O5-K2O-Na2O-CaF2 glass system, then melted, quenched and milled to give fine glass powders. DTA thermograms for the three glass compositions showed crystallization temperatures between 720 and 760°C and Tg ranging between 508 and 645°C. Porous glass-ceramics were characterized for bulk density, phase evolution and microstructures. Different compositions resulted in different bulk densities and phases that crystallized out. Fluorapatite …