Engineering Commons^™

Dependence Of Photoelectrochemical Properties On Geometry Factors Of Interconnected “Caterpillar-Like” Zno Networks, Qiang Li, Xing Sun, Karen Lozano, Yuanbing Mao

Mechanical Engineering Faculty Publications and Presentations

Highlights

• Hierarchical “caterpillar-like” ZnO nanostructures have been prepared through a hybrid route.

• The ease and high throughput of the method favors a feasible PEC applications.

• The tunability of the geometric factors could optimize the light-material interaction.

• Ultralong and ultrathin branches shorten minority carrier diffusion lengths to further improve PEC performance.

Abstract

To elevate the spatial occupancy of one-dimensional ZnO nanostructures and overcome the limitations of multistep seeding methods currently widely used, a rational, facile and high-yielding procedure has been reported by our group previously for the fabrication of the interconnected three-dimensional “caterpillar-like” ZnO nanostructured networks (CZNs) for photoelectrochemical applications. In …

Front Dynamics And Entrainment Of Finite Circular Gravity Currents On An Unbounded Uniform Slope, ‪Nadim Zgheib, A. Ooi, S. Balachandar

Mechanical Engineering Faculty Publications and Presentations

We report on the dynamics of circular finite-release Boussinesq gravity currents on a uniform slope. The study comprises a series of highly resolved direct numerical simulations for a range of slope angles between 5∘ and 20∘ . The simulations were fixed at Reynolds number Re=5000 for all slopes considered. The temporal evolution of the front is compared to available experimental data. One of the interesting aspects of this study is the detection of a converging flow towards the centre of the gravity current. This converging flow is a result of the finite volume of the release coupled with the presence …

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 …

Mechanical And Electrical Characterization Of Carbon Nanofibers Produced From Water Soluble Precursors, Lee D. Cremar, Javier Acosta-Martinez, Alexsandra Villarreal, Alfonso Salinas, Karen Lozano

Mechanical Engineering Faculty Publications and Presentations

This study presents the thermo-physical, electrical, and mechanical characterization of fine carbon fibers produced from water-soluble polymer precursors and low temperature processes. These fibers were developed utilizing the Forcespinning® technology which utilizes centrifugal force to spin fibers. Polyvinyl alcohol was used as the precursor material, and fibers were developed and deposited in a non-woven configuration. The resultant non-woven fiber mats were subjected to a dehydration process through exposure to sulfuric acid vapors. The partially carbonized mats were heat treated at 850 °C. The produced porous nonwoven carbon fiber based mats have micro-and mesoporosity with a final fiber average diameter of …

Parametric Analysis Of A Solid Oxide Fuel Cell Auxiliary Power Unit Operating On Syngas Produced By Autothermal Reforming Of Hydrocarbon Fuels, Jun Dong, Xinhai Xu, Ben Xu, Shuyang Zhang

Mechanical Engineering Faculty Publications and Presentations

A 1 kWe integrated auxiliary power unit (APU) system consisting of an autothermal reformer and a solid oxide fuel cell (SOFC) unit, as well as balance-of-plant components, was designed and analyzed. A relatively easy-to-approach SOFC model was developed in order to conveniently calculate V-I and P-I curves and the system's net efficiency at different operating conditions. The effects of steam to carbon and oxygen to carbon ratios in the reactants, channel dimensions of the SOFC unit, and hydrocarbon fuel types on the integrated APU system's performance were discussed. Five hydrocarbon fuels including diesel, Jet-A, gasoline, ethanol, and methanol were studied …

Knee Internal Forces In Moderate Squat Exercise, Dumitru I. Caruntu, Jose Mario Salinas

Mechanical Engineering Faculty Publications and Presentations

This paper deals with internal forces of human knee during moderate squat exercise. The moderate squat exercise consists of a descending phase from standing to the lowest position (largest flexion angle) in which no significant contact between thigh and calf occurs, and an ascending phase back to standing position. This research predicts the internal forces such as muscle forces, contact forces, and ligamentous forces. The ligamentous structures in this research consist of Anterior Cruciate Ligament (ACL), Posterior Cruciate Ligament (PCL), Lateral Collateral Ligament (LCL), and Medial Collateral Ligament (MCL). The ligaments are modeled as nonlinear elastic strips (they do not …

Production Of Β-Silicon Carbide Nanofibers Using The Forcespinning® Method, Alfonso Salinas, Aleksey Altecor, Maricela Lizcano, Karen Lozano

Mechanical Engineering Faculty Publications and Presentations

Silicon carbide (SiC) nanofibers were produced on a large scale using the Forcespinning® method. Non-oxide ceramics such as SiC are known for their low density, oxidation resistance, thermal stability, and wear resistance. The nanofibers were prepared using a solution-based method with polystyrene and polycarbomethylsilane as the precursor materials. Fiber spinning was performed under different parameters to obtain high yield, fiber homogeneity, and small diameters. The fibers were spun under a controlled nitrogen environment to prevent fiber oxidation. The resultant nonwoven nanofiber mats were then subjected to different heat treatments to evaluate the effect of these on the crystalline structure. Characterization …