Engineering Commons^™

Degradation Of High Performance Polymeric Fibers: Effects Of Sonication, Humidity And Temperature On Poly (P-Phenylene Terephthalamide) Fibers, Nelyan Lopez-Perez

Open Access Theses

High performance fibers are characterized by properties such as high strength and resistance to chemicals and heat. Due to their outstanding properties, they are used on applications under harsh environments that can degrade and decrease their performance. Fiber degradation due to different chemical and mechanical factors, is a process that begins at a microstructural level. Changes in the polymer’s chemical or physical structure can alter their mechanical properties. Knowledge of the structure-properties relationship and the effects of environmental chemical and physical factors over time, is crucial for the improvement and development of high performance fibers.

In this study ballistic fibers …

Experimental Investigation Of The Velocity Field In Buoyant Diffusion Flames Using Piv And Tpiv Algorithm, Lulu Sun, Xiangyang Zhou, Shankar Mahalingam, David R. Weise

Lulu Sun

We investigated a simultaneous temporally and spatially resolved 2-D velocity field above a burning circular pan of alcohol using particle image velocimetry (PIV). The results obtained from PIV were used to assess a thermal particle image velocimetry (TPIV) algorithm previously developed to approximate the velocity field using the temperature field, simultaneously captured by an infrared (IR) thermal camera. By tracing “thermal particles,” which were assumed to be virtual particles that corresponded to pixels of temperature values in successive IR images, the TPIV algorithm estimated a larger scale instantaneous velocity field than either a single-point velocity measurement (e.g., LDV) or the …

Formation Of Trihalomethanes (Thms) As Disinfection By-Products (Dbps) When Treated Municipal Wastewater Is Disinfected With Sodium Hypochlorite, Helene Kassouf

USF Tampa Graduate Theses and Dissertations

Disinfection is an essential process in the treatment of municipal wastewater before the treated wastewater can be discharged to the environment. Hillsborough County's Northwest Regional Water Reclamation Facility (NWRWRF) in Tampa, Florida, currently uses ultraviolet (UV) light for disinfection. However, this method has proven expensive to implement and maintain, and may not be effective if the light transmission is poor. For these reasons, Hillsborough County is considering switching from UV light to sodium hypochlorite for disinfection. However, hypochlorite (chlorine) disinfection has disadvantages as well, such as the production of disinfection by-products (DBPs) such as trihalomethanes (THM) and haloacetic acids (HAAs), …

Aggies In The Arctic: Usu Environmental Engineers Decode Icy Watersheds | College Of Engineering, Usu College Of Engineering

College of Engineering News

Published in Creating Tomorrow – Oct. 15, 2016 – When it comes right down to it, scientists and environmental engineers will tell you that nearly every ecosystem on Earth is driven by one simple thing: temperature.

Oceans, rivers, forests and deserts are a product of the chemical and biological processes that depend on a predictable mix of hot and cold. Even in the Arctic, where shallow soils are frozen most of the year, tiny variations in temperature can impact entire regions.

Heat Management Strategies For Msw Landfills, Nazli Yesiller, James L. Hanson, Kevin B. Kopp, Emma H. Yee

Civil and Environmental Engineering

Heat is a primary byproduct of landfilling of municipal solid waste. Long-term elevated temperatures have been reported for MSW landfills under different operational conditions and climatic regions around the world. A conceptual framework is presented for management of the heat generated in MSW landfills. Three main strategies are outlined: extraction, regulation, and supplementation. Heat extraction allows for beneficial use of the excess landfill heat as an alternative energy source. Two approaches are provided for the extraction strategy: extracting all of the excess heat above baseline equilibrium conditions in a landfill and extracting only a part of the excess heat above …

Go With The Flow –Thermoelectric Energy, Shawn Bell

Middle School Lesson Plans

In this unit, students will learn how thermal energy be transferred and transformed. They will carry out investigations to gather evidence to support an explanation about direct conversion of heat into electrical energy. They will develop a model that shows the components of the system and changes in the system being investigated, and they will use evidence from the investigation to construct an explanation for how the energy flows.

Heat Generation In The Railroad Bearing Thermoplastic Elastomer Suspension Element, Oscar O. Rodriguez, Juan Carbone, Arturo A. Fuentes, Robert E. Jones, Constantine Tarawneh

Mechanical Engineering Faculty Publications and Presentations

The main purpose of this ongoing study is to investigate the effect of heat generation within a railroad thermoplastic elastomer suspension element on the thermal behavior of the railroad bearing assembly. Specifically, the purpose of this project is to quantify the heat generated by cyclic loading of the elastomer suspension element as a function of load amplitude, loading frequency, and operating temperature. The contribution of the elastomer pad to the system energy balance is modeled using data from dynamic mechanical analysis (DMA) of the specific materials in use for that part. DMA is a technique that is commonly used to …

Temperature Profiles Of Railroad Tapered Roller Bearings With Defective Inner And Outer Rings, Constantine Tarawneh, Luz Sotelo, Anthony A. Villarreal, Nancy De Los Santos, Ryan L. Lechtenberg, Robert Jones

Mechanical Engineering Faculty Publications and Presentations

In the railroad industry, monitoring the condition of key components such as bearings and wheels is vital to ensure the safe transport of goods and commodities. Bearing seizures are amongst the most dangerous types of failures experienced by trains because they occur unexpectedly and may lead to costly derailments. Current bearing health monitoring techniques include tracking the temperature and acoustic emissions given by the bearings. Although temperature histories of railroad tapered roller bearings are readily available, the literature does not provide information relating the temperature profiles to the severity of the bearing defect. The study presented here investigates the correlation …

Moisture And Temperature Effects On Interface Mechanical Properties For External Bonding, Tamon Ueda, Justin Shrestha, Khuram Rashid, Dawei Zhang

International Conference on Durability of Concrete Structures

In order to develop rational guidelines for strengthening by external bonding, it is necessary to clarify longterm performance of interfacial bonding property. In this paper, moisture effects on bonding properties at FRP–concrete interface and temperature/moisture effects on bonding properties at PCM–concrete interface are presented. Shear bond strength of FRP–concrete interface is affected by moisture because resin–concrete adhesion strength is affected by moisture. Among tested CFRP external bonding systems, wet-layup CFRP systems all show the strength reduction, while prefabricated CFRP systems all show the strength increase after immersion. The bond stress–slip relationship and interfacial fracture energy also change, which can explain …

Heat Of Fusion Of Primary Alcohol Confined In Nanopores, Harrisonn Griffin

Honors Theses

Melting behavior of physically confined 1-decanol in nano porous silica was probed using a Differential Scanning Calorimeter (DSC). In agreement with the Gibbs-Thomson prediction, we observe that the melting temperature of the confined 1-decanol scales inversely with the physical size of the pores. Contrary to the assumption used in developing the Gibbs-Thomson equation, however, the apparent heat of fusion decreases as the pore size decreases. Previously, several models have been proposed where interfacial layers of molecules do not participate in the phase transition and thereby would not contribute to the heat of fusion. While these could reconcile the seeming contradiction, …

The Effects Of Latency On 3d Interactive Data Visualizations, Allen Korenevsky

Master's Theses

Interactive data visualizations must respond fluidly to user input to be effective, or so we assume. In fact it is unknown exactly how fast a visualization must run to present every facet within a dataset. An engineering team with limited resources is left with intuition and estimates to determine if their application performs sufficiently well.

This thesis studies how latency affects users' comprehension of data visualizations, specifically 3D geospatial visualizations with large data sets. Subjects used a climate visualization showing temperatures spanning from the 19th to the 21st century to answer multiple choice questions. Metrics like their eye movements, time …

Bbq Grill Temperature Uniformity Study, Monty Dodge Jr, Samuel Melo

Mechanical Engineering

Bull Outdoor Products, Incorporated, a barbeque grill and outdoor kitchen manufacturer, sponsored this project with the intent of improving the temperature uniformity across the surface of their barbecue grills. For this project, the Cal Poly team of mechanical engineering students, Monty Dodge Jr. and Samuel Melo, used the Brahma grill head model with setups for both natural gas and propane. In order to determine exactly what the uniformity across the grill surface was, the student team designed a testing apparatus which would measure a grid of temperature locations one inch apart spanning an area 16 by 36 inches. Developing a …

Flying By Fire: Making Controlled Burns Safer For Humans And Uavs, Rebecca Horzewski, Carrick Detweiler

UCARE Research Products

A temperature sensing circuit board was developed that will allow Nimbus Lab's controlled burn starting UAV to react to the temperatures around it.

Strain Monitoring Of Bismaleimide Composites Using Embedded Microcavity Sensor, Amardeep Kaur, Sudharshan Anandan, Lei Yuan, Steve Eugene Watkins, K. Chandrashekhara, Hai Xiao, Nam Phan

Electrical and Computer Engineering Faculty Research & Creative Works

A type of extrinsic Fabry-Perot interferometer (EFPI) fiber optic sensor, i.e., the microcavity strain sensor, is demonstrated for embedded, high-temperature applications. The sensor is fabricated using a femtosecond (fs) laser. The fs-laser-based fabrication makes the sensor thermally stable to sustain operating temperatures as high as 800 °C. The sensor has low sensitivity toward the temperature as compared to its response toward the applied strain. The performance of the EFPI sensor is tested in an embedded application. The host material is carbon fiber/bismaleimide (BMI) composite laminate that offer thermally stable characteristics at high ambient temperatures. The sensor exhibits highly linear response …

Temperature Effects On Properties Of Aerospace Nickel Hydrogen Cells, Hai-Chang Zhang, Yu-Qi Diao, Wen-Cheng Ming, Xue-Ying Ren, Fei Ding

Journal of Electrochemistry

This has been done using the 60 Ah nickel-hydrogen cell to investigate the temperature effects on properties of aerospace nickel hydrogen cells. The charge-discharge, trickle charge, overcharge, self-discharge and cycle life tests were carried out at different temperatures. The results show that the discharge capacity and overcharge rate were increased first, and then decreased with the raising temperature. On the other hand, the trickle charge value and the 3 days self-discharge rate were raised with increasing temperature. When the temperature was -5 ^oC, the discharge capacity of cell reached the maximum discharge capacity of 63.68 Ah. Based on the …

High Intrinsic Sensitivity Etched Polymer Fiber Bragg Grating Pair For Simultaneous Strain And Temperature Measurements, Kishore Bhowmik, Gang-Ding Peng, Yanhua Luo, Eliathamby Ambikairajah, Vedran Lovric, William R. Walsh, Ginu Rajan

Faculty of Engineering and Information Sciences - Papers: Part A

A sensing configuration for simultaneous measurement of strain and temperature with enhanced intrinsic sensitivity based on a fiber Bragg grating (FBG) pair with one grating inscribed in the etched and the other in unetched polymer fiber region is demonstrated. A poly (methyl methacrylate) based single-mode polymer fiber is etched to different diameters, and it is observed that etching can lead to change in the material properties of the fiber, such as Young's modulus and thermal expansion coefficient, which can play a vital role in improving its intrinsic sensing capabilities. Thus, exploiting the different strain and temperature sensitivities exhibited by etched …

Influence Of Cr-Rich Oxide Scale On Sliding Wear Mechanism Of Ferritic Stainless Steel At High Temperature, Xiawei Cheng, Zhengyi Jiang, Buyung Kosasih, Hui Wu, Suzhen Luo, Laizhu Jiang

Faculty of Engineering and Information Sciences - Papers: Part A

The tribological tests of a ferritic stainless steel (FSS) 445 in contact with high-speed steel (HSS) were performed on a high-temperature pin-on-disc tribometer. Wear exhibited significant difference when the FSS 445 was oxidised with a Cr-rich oxide scale on the surface. The HSS pin displayed adhesive wear when there was no oxide scale on the stainless steel disc, and in the early stages, the coefficient of friction fluctuated significantly, but the level of wear changed as Cr2O3 particles formed. The wear was then reduced, and the coefficient of friction remained stable. The Cr-rich oxide scale which formed on the stainless …

Simultaneous Grain Growth And Grain Refinement In Bulk Ultrafine-Grained Copper Under Tensile Deformation At Room Temperature, Hai Liang Yu, Cheng Lu, Anh Kiet Tieu, Hui Jun Li, Ajit R. Godbole, Charlie Kong, Xing Zhao

Faculty of Engineering and Information Sciences - Papers: Part A

Grain growth and grain refinement behavior during deformation determine the strength and ductility of ultrafine-grained materials. We used asymmetric cryorolling to fabricate ultrafine-grained copper sheets with an average grain width of 230 nm and having a laminate structure. The sheets show a high-true failure strain of 1.5. Observation of the microstructure at the fracture surface reveals that ultrafine laminate-structured grains were simultaneously transformed into both equiaxed nanograins and coarse grains under tensile deformation at room temperature.

Transient Cfd Modelling Of Low-Temperature Spontaneous Heating Behaviour In Multiple Coal Stockpiles With Wind Forced Convection, Jian Zhang, Yuntao Liang, Ting X. Ren, Zhongwei Wang, Gongda Wang

Faculty of Engineering and Information Sciences - Papers: Part A

Spontaneous heating of coal stockpile has long been a thermal dynamic hazard during coal storage, processing, and transport. A transient non-equilibrium thermal CFD model has been developed to study the low-temperature self-heating behaviour of coal in multiple stockpiles under different prevailing wind conditions. Modelling results from the initial steady wind flow simulation indicate that a wake region can be induced on the leeward side of each coal stockpile. Pressure coefficient drops when the wind stream encounters or leaves a stockpile and the pressure coefficient profiles of multiple stockpiles tend to have more resemblance with a wider spacing. The first stockpile …

High Temperature Oxidation Of Indefinite Chill Roll Material Under Dry And Humid Atmospheres, Liang Hao, Zhengyi Jiang, Zhixin Chen, Dongbin Wei, Xiawei Cheng, Jingwei Zhao, Ming Luo, Li Ma, Suzhen Luo, Laizhu Jiang

Faculty of Engineering and Information Sciences - Papers: Part B

In this paper, the isothermal oxidation of the indefinite chill (IC) roll is investigated by using a thermogravimetric analyzer (TGA) from 550 to 700 °C under dry and humid atmospheres. It is found that the oxidation kinetics follow a linear trend and the oxide scale consists of two layers after the oxidation in dry air but three layers in humid air above 600 °C. In dry air, the graphite is covered by the oxide scale above 650 °C. The water vapor accelerates the oxidation of the matrix and the graphite. The graphite is covered by the extension of the oxide …

Improved Superconducting Properties In The Mg11b2 Low Activation Superconductor Prepared By Low-Temperature Sintering, Fang Cheng, Yongchang Liu, Zongqing Ma, M Shahriar Al Hossain, Mehmet Somer

Australian Institute for Innovative Materials - Papers

Mg11B2 has a great application prospect in the superconducting coils for fusion reactor as the "low activation superconductors". The un-doped Mg11B2 and Cu-doped Mg11B2 bulks using 11B as a boron precursor were fabricated by low-temperature sintering in present work. It was found that the prepared Mg11B2 low activation superconductors exhibit better Jc performance than all of other Mg11B2 samples reported in previous studies. As for Cu doped Mg11B2, minor Cu addition can obviously improve the Mg11B2 grain crystallization and reduce the amount of MgO impurity. Hence, improved grain connectivity and higher Jc at low fields is obtained in Cu doped …

Kicm: A Knowledge-Intensive Context Model, Fredrick Mtenzi, Denis Lupiana

Conference papers

A context model plays a significant role in developing context-aware architectures and consequently on realizing context-awareness, which is important in today's dynamic computing environments. These architectures monitor and analyse their environments to enable context-aware applications to effortlessly and appropriately respond to users' computing needs. These applications make the use of computing devices intuitive and less intrusive. A context model is an abstract and simplified representation of the real world, where the users and their computing devices interact. It is through a context model that knowledge about the real world can be represented in and reasoned by a context-aware architecture. This …

Deflector Effects In Fixed Bed (Biomass) Combustors And Non-Combusting Packed Beds, Babak Rashidian

Theses: Doctorates and Masters

Combustion can be used to thermally process biomass fuels and yield both heat and power in a sustainable manner. At present, direct combustion of solid biomass is the primary approach for generating electricity and heat when these fuels are used at a commercial scale.

Deflectors have been used in the freeboard section of industrial combustors to reduce radiant heat loss through flue gases and for particle emissions abatement. Freeboard deflectors can also influence emissions and freeboard temperature distributions by changing the flow dynamics. Despite much research into laboratory scale biomass combustion and packed beds, there have been no systematic studies …

Thermal Model Of Oil Power Transformers With A Tap Changer, Zoran Radakovic, Stefan Tenbohlen

Turkish Journal of Electrical Engineering and Computer Sciences

No abstract provided.

Oxidation Resistance Of Nanocrystalline 316l Stainless Steel Processed By High Pressure Torsion, Kevin J. Meisner

Williams Honors College, Honors Research Projects

High Pressure Torsion (HPT) is a materials processing method used to refine the grain size of metallic materials through the application of simultaneous axial and torsional strain. HPT is reported to result in nanocrystalline structure, which the current scientific literature suggests may improve the high temperature oxidation resistance by enhancing diffusion of solutes, particularly Cr, to the surface to form a protective external oxide scale. If oxidation resistance is improved, this possibly allows the use of 316L in oxidizing environments where more expensive alloys are typically used. However, the influence of grain refinement to nanoscale on various properties have been …

The Effects Of Micro-Dimple Texture On The Friction And Thermal Behavior Of A Point Contact, Utsav Kamleshbhai Parmar

Browse all Theses and Dissertations

This study investigates the effects of the micro-dimple texture on the friction and surface temperature performances of a ball-on-disk contact, operating under the speed and load ranges that cover typical gearing applications. Circular shaped micro-dimple arrays with different dimple center distances and dimple depths are implemented on the ball surface to quantify the impacts of these two parameters on the friction coefficient and the maximum ball surface temperature. In addition, the contacts of three surface texture combinations, namely micro-dimpled and polished ball surface versus polished disk surface, polished ball surface versus polished disk surface and ground ball surface versus ground …