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Open Access Theses & Dissertations

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Full-Text Articles in Engineering

Zinc Telluride Deposition Using Close Space Sublimation, Luis Carlos Romo Jan 2008

Zinc Telluride Deposition Using Close Space Sublimation, Luis Carlos Romo

Open Access Theses & Dissertations

This thesis presents the optimization process of the close space sublimation (CSS) technique to deposit zinc telluride (ZnTe) on thin-film cadmium telluride (CdTe) solar cells. Previous research has demonstrated that creating a heavily doped ZnTe intermediate layer between the absorber-CdTe and the back contacts produces low-resistive CdTe contacts that overcome the Schottky barrier created at the interface of a metal and a semiconductor [11]. ZnTe interlayer forms a tunnel barrier at the contact interface so the positive charges created at the p-CdTe/n-cadmium sulfide (CdS) junction can be easily collected at the back contact maximizing the current collection process. However, ZnTe …


Quality Evaluation Of Portland Cement Concrete At Early Age With Free-Free Resonant Column, Gilberto Wenglas Jan 2008

Quality Evaluation Of Portland Cement Concrete At Early Age With Free-Free Resonant Column, Gilberto Wenglas

Open Access Theses & Dissertations

At early age, the behavior and mechanical properties of portland cement concrete changes rapidly with time due to hydration. The hydration process consists of a series of chemical reactions that accelerate nonlinearly with the rise in temperature. The hydration process consists of three stages: the dormant period, the setting time, and the hardening time. Timely opening of roads and resumption of constructions depend of the knowledge of these stages. The initial and final setting times are arbitrarily determined by a standard test (ASTM C 403). Although the setting time has been studied for many decades, the new technologies allow making …


Meso-Machining Of Miniature Space System Components, Carlos Ramirez Jan 2007

Meso-Machining Of Miniature Space System Components, Carlos Ramirez

Open Access Theses & Dissertations

Many industries in engineering and science are focusing more on producing mechanisms and system components of magnitudes smaller than existing products. One of the major technologies associated with these demands is the development of meso scale precision manufacturing systems. Meso scale fabrication involves the scaling down of conventional machining to incorporate the use of familiar materials, such as aluminum, steel, and even titanium for machining miniature components. New techniques in meso scale fabrication allow for the machining of miniature space system components in an efficient manner to meet certain specifications. A description of the processes used to accurately machine a …


A Pda Based Recording System To Investgate Heart Rate, Marcos Efren Bolanos Jan 2007

A Pda Based Recording System To Investgate Heart Rate, Marcos Efren Bolanos

Open Access Theses & Dissertations

Diabetes is one of most afflicting diseases in society which is caused by the inability of the body to appropriately use insulin to balance sugar levels. Type 1 diabetics require monitoring of their glucose levels to ensure a normal glucose level is maintained between 90 and 130 mg/dL (milligrams per deciliter). Unfortunately, current methods of monitoring are based on invasive and painful sampling of the blood. It was imperative that noninvasive and painless methods of monitoring glucose should be explored. A proven noninvasive technique utilizing infrared light to detect the fluctuations in the heart rate was used to determine if …


Uplift Capacity Of Rigid Pile In Clay Under Inclined Load, Godwin Ikechukwu Ubanyionwu May 1985

Uplift Capacity Of Rigid Pile In Clay Under Inclined Load, Godwin Ikechukwu Ubanyionwu

Open Access Theses & Dissertations

This thesis investigates the uplift capacity of rigid vertical piles embedded in saturated or near-saturated clayey soils subjected to inclined uplifting loads. Pile foundations are widely used in civil engineering applications requiring resistance to both axial and lateral forces, including transmission tower foundations, foundations on expansive soils, and mat foundations in areas subject to rising groundwater tables. While considerable research had addressed compressive load bearing capacity and lateral resistance of piles, experimental data on pile behavior under inclined uplift loading remained scarce at the time of this study. The present study was undertaken to conduct a systematic series of laboratory …