Mechanical Engineering Commons^™

Optimization-Based Power Management Of Hybrid Power Systems With Applications In Advanced Hybrid Electric Vehicles And Wind Farms With Battery Storage, Hoseinali Borhan

All Dissertations

Modern hybrid electric vehicles and many stationary renewable power generation systems combine multiple power generating and energy storage devices to achieve an overall system-level efficiency and flexibility which is higher than their individual components. The power or energy management control, ``brain' of these ``hybrid' systems, determines adaptively and based on the power demand the power split between multiple subsystems and plays a critical role in overall system-level efficiency. This dissertation proposes that a receding horizon optimal control (aka Model Predictive Control) approach can be a natural and systematic framework for formulating this type of power management controls. More importantly the …

Effect Of Relative Humidity And Temperature Control On In-Cabin Thermal Comfort State, Ali Alahmer

All Dissertations

This dissertation discusses the effect of manipulating the relative humidity RH levels inside vehicular cabins on the thermal comfort and human occupants' thermal sensation. Three different techniques are used to investigate this effect. Firstly, thermodynamic and psychometric analyses are used to incorporate the effect of changing RH along with the dry bulb temperature on the human comfort window. Specifically, the study computes the effect of changing the relative humidity on the amount of heat rejected from the passenger compartment and the effect on occupants comfort zone. A practical system implementation is also discussed in terms of an evaporative cooler design. …

Fabrication Of Grooved Hollow Fiber Membrane For Nerve Regeneration: Process Modeling And Performance Evaluation, Jun Yin

All Dissertations

Nerve injury is a general but intractable disease in traumatic injuries, leading to a significant reduction of functions in the nervous system. Extensive efforts are made on nerve injury rehabilitation. Since the appropriate connections between neurons and their targets are necessary, guiding axonal outgrowth is an essential step for neuron outgrowth in nervous system development, functioning, and regeneration. Besides the direct surgical nerve connection, an artificial means of guiding nerve regeneration called nerve conduits is widely applied in nerve injury rehabilitation. The main function of nerve conduits is to bridge the nerve gap, to help regenerating axons across damaged regions …

Asymptotic Multiphysics Modeling Of Composite Beams, Qi Wang

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A series of composite beam models are constructed for efficient high-fidelity beam analysis based on the variational-asymptotic method (VAM). Without invoking any a priori kinematic assumptions, the original three-dimensional, geometrically nonlinear beam problem is rigorously split into a two-dimensional cross-sectional analysis and a one-dimensional global beam analysis, taking advantage of the geometric small parameter that is an inherent property of the structure.

The thermal problem of composite beams is studied first. According to the quasisteady theory of thermoelasticity, two beam models are proposed: one for heat conduction analysis and the other for thermoelastic analysis. For heat conduction analysis, two different …

Evaluation Of An Incompressible Energy-Vorticity Turbulence Model For Fully Rough Pipe Flow, Doug F. Hunsaker

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Traditional methods of closing the Boussinesq-based Reynolds-averaged Navier-Stokes equations are considered, and suggestions for improving two-equation turbulence models are made. The traditional smooth-wall boundary conditions are shown to be incorrect, and the correct boundary conditions are provided along with sample solutions to traditional models. The correct boundary condition at a smooth wall for dissipation-based turbulence models is that which forces both the turbulent kinetic energy and its first derivative to zero. Foundations for an energy-vorticity model suggested by Phillips are presented along with the near-smooth-wall behavior of the model. These results show that at a perfectly smooth wall, the turbulent …

Axisymmetric Finite Element Modeling Of Adhesive Joint Between A Laminated Composite And Metal Cylinder, Casey A. Talbot

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Because lowering weight as much as possible is desirable in all applications designed to go to space, the use of composite materials is desirable. Composites are materials that are made up of two or more separate materials usually with significantly different characteristics which remain separate and distinct in their completed state. Fiber-reinforced epoxy composites, in general, are very strong and light. Because most space structures cannot solely be made of composites, a method to join them with metals is needed. Adhesive joining, or gluing, has been determined to be the most promising option.

For the joining technique to be used, …

Optimization Of A Low Reynold's Number 2-D Inflatable Airfoil Section, Todd A. Johansen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A stand-alone genetic algorithm (GA) and an surrogate-based optimization (SBO) combined with a GA were compared for accuracy and performance. Comparisons took place using the Ackley Function and Rastrigin's Function, two functions with multiple local maxima and minima that could cause problems for more traditional optimization methods, such as a gradient-based method. The GA and SBO with GA were applied to the functions through a fortran interface and it was found that the SBO could use the same number of function evaluations as the GA and achieve at least 5 orders of magnitude greater accuracy through the use of surrogate …

Influence Of Supraglottal Geometry And Modeling Choices On The Flow-Induced Vibration Of A Computational Vocal Fold Model, Timothy E. Shurtz

Theses and Dissertations

Computational models of the flow-induced vibrations of the vocal folds are powerful tools that can be used in conjunction with physical experiments to better understand voice production. This thesis research has been performed to contribute to the understanding of vocal fold dynamics as well as several aspects of computational modeling of the vocal folds. In particular, the effects of supraglottal geometry have been analyzed using a computational model of the vocal folds and laryngeal airway. In addition, three important computational modeling parameters (contact line location, Poisson's ratio, and symmetry assumptions) have been systematically varied to determine their influence on model …

Dynamics And Stability Of Two-Potential Flows In The Porous Media, Bojan Markicevic, Branko Bijeljic, Homayun K. Navaz

Mechanical Engineering Publications

The experimental and numerical results of the capillary-force-driven climb of wetting liquid in porous media, which is opposed by the gravity force, are analyzed with respect to the emergence of a multiphase flow front and flow stability of the climbing liquid. Two dynamic characteristics are used: (i) the multiphase flow front thickness as a function of time, and (ii) the capillary number as a function of Bond number, where both numbers are calculated from the harmonic average of pores radii. Throughout the climb, the influence of capillary, gravity, and viscous force variations on the flow behavior is investigated for different …

Molecular Diffusion And Slip Boundary Conditions At Smooth Surfaces With Periodic And Random Nanoscale Textures, Nikolai V. Priezjev

Mechanical and Materials Engineering Faculty Publications

The influence of periodic and random surface textures on the flow structure and effective slip length in Newtonian fluids is investigated by molecular dynamics (MD) simulations. We consider a situation where the typical pattern size is smaller than the channel height and the local boundary conditions at wetting and nonwetting regions are characterized by finite slip lengths. In case of anisotropic patterns, transverse flow profiles are reported for flows over alternating stripes of different wettability when the shear flow direction is misaligned with respect to the stripe orientation. The angular dependence of the effective slip length obtained from MD simulations …

One-Step Infiltration Of Mixed Conducting Electrocatalysts For Reducing Cathode Polarization Of A Commercial Cathode-Supported Sofc, Nansheng Xu, Xue Li, Xuan Zhao, Hailei Zhao, Kevin Huang

Faculty Publications

Infiltrating fine-grained electrocatalyst particles of either ion conducting or mixed electron and ion conducting (MEIC) material into a ceramic porous electrode scaffold has proven a very effective way to improve electrode performance for low to intermediate temperature solid oxide fuel cells (SOFCs). We report here one-step infiltration of MEIC fine particles, La_0.6Sr_0.4CoO_3-δ (LSCo) and SrCo_0.8Fe_0.2O_3-δ (SCF), into a commercial cathode substrate. A comparative study shows that the cathode polarization can be considerably reduced by a factor of 17 to 28 and 28 to 49 from 1000 to 700 ³C by …

On The Effect Of Functionally Graded Materials On Resonances Of Rotating Beams, Arnaldo J. Mazzei Jr.

Mechanical Engineering Publications

Radially rotating beams attached to a rigid stem occur in several important engineering applications. Some examples include helicopter blades, turbine blades and certain aerospace applications. In most studies the beams have been treated as homogeneous. Here, with a goal of system improvement, non-homogeneous beams made of functionally graded materials are explored. The effects on the natural frequencies of the system are investigated. Euler-Bernoulli theory, including an axial stiffening effect and variations of both Young's modulus and density, is employed. An assumed mode approach is utilized, with the modes taken to be beam characteristic orthogonal polynomials. Results are obtained via Rayleigh-Ritz …

Solid Oxide Fuel Cell Process And Apparatus, Mathew Ellis Cooper, David J. Bayless, Jason P. Trembly

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Conveying gas containing sulfur through a sulfur tolerant planar solid oxide fuel cell (PSOFC) stack for sulfur scrubbing, followed by conveying the gas through a non-sulfur tolerant PSOFC stack. The sulfur tolerant PSOFC stack utilizes anode materials, such as LSV, that selectively convert H₂S present in the fuel stream to other non-poisoning sulfur compounds. The remaining balance of gases remaining in the completely or near H₂S-free exhaust fuel stream is then used as the fuel for the conventional PSOFC stack that is downstream of the sulfur-tolerant PSOFC. A broad range of fuels such as gasified coal, …

Microstructural Evaluation In Friction Stir Welded High Strength Low Alloy Steels, Majid Abbasi Gharacheh

Theses and Dissertations

Understanding microstructural evolution in Friction Stir Welding (FSW) of steels is essential in order to understand and optimize the process. Ferritic steels undergo an allotropic phase transformation. This makes microstructural evolution study very challenging. An approach based on Electron Backscattered Diffraction (EBSD) and phase transformation orientation relationships is introduced to reconstruct pre-transformed grain structure and texture. Reconstructed pre-transformed and post-transformed grain structures and textures were investigated in order to understand microstructural evolution. Texture results show that there is evidence of shear deformation as well as recrystallization in the reconstructed prior austenite. Room temperature ferrite exhibits well-defined shear deformation texture components. …

Effect Of Copper Addition On Mechanical Properties And Electrical Conductivity Of Pp/C-Cu Bipolar Plate Composites, Anne Zulfia, Taufik Abimanyu, Verina Warga Dalam

Makara Journal of Technology

Effect of Copper Addition on Mechanical Properties and Electrical Conductivity of PP/C-Cu Bipolar Plate Composites. Bipolar plate is a major component in PEM fuel cell which possess main function of collecting and removing electrons from anode to cathode. Therefore, materials for bipolar plates produced must have high electrical conductivity. To obtain bipolar plate materials which is cheap, lightweight and high conductivity, so it is developed bipolar plates material based on PP/C-Cu composite. PP/C-Cu composites has been made by mixing all materials then compounding, rheomix, hot blending and hot press. Cu (Copper) has been used various from 0.1 wt%, 1 wt% …

Application Of Empirical Orthogonal Function Models To Analyze Shoreline Change At Bangkalan Madura, Darius Arkwright, Suntoyo Suntoyo

Makara Journal of Technology

Bangkalan’s shoreline, especially on the opposite side of Surabaya, has been evaluated to determine the morphological changes due to wave attack, near-shore current, long-shore sediment transport and coastal configuration. This research aims to determine the dominant patterns of variation of Bangkalan’s shoreline change, expressed by Eigen-function in empirical orthogonal function (EOF) models. That was started with data collection such as oceanographic data (wave and tidal), bathymetry and topographic map and sediment data. All data was used for forecasting two-monthly shoreline. Coordinate of two-monthly shoreline was used as input of EOF model. The first Eigen mode is a profile of shoreline …

The Effectiveness Of Anaerobic Baffled Reactor And Rotating Biological Contactor In Batik Wastewater Treatment, Augustinus Ignatius Kristijanto, Widhi Handayani, Purwanti Asih Anna Levi

Makara Journal of Technology

Batik is one of popular arts of Indonesia. The batik industries in Sragen, Central Java, are prepared to compete in global market. In order to realize that objective, batik products should fulfill some qualifications, one of which is “environmental friendliness”. As batik production is usually generating wastewater which pollutes the environment, the technology of wastewater treatment should be developed to solve the problem. This preliminary study has been done to assess the effectiveness of anaerobic baffled reactor (ABR) and rotating biological contactor (RBC) in batik wastewater treatment. In 40 days of treatment period, the ABR performance in reducing pollutants showed …

Physical Characterization And Desulfurization Of Biobriquette Using Calcium-Based Adsorbent, Mahidin Mahidin, Asri Gani, Khairil Khairil

Makara Journal of Technology

Combustion of coal and co-combustion of their co-fuel contribute to gas emissions. Among the gas emissions are SOx, NOx, CO and CO2. Introduction of calcium based adsorbent is addressed to absorb SO2 that release to the atmosphere during the combustion process. Objective of the research is at first to observe the physical characteristics of biobriquettes as a function of briquette compositions (coal to palm kernel shell ratios) and Ca/S ratios (Ca in adsorbent and S in briquette) using a natural adsorbent (shellfish waste). The second objective is to investigate desulfurization characteristics as a function of Ca/S ratios and desulfurization temperatures …

Medium Density Fibreboard Made Of Acetylated Sludge From Paper Mill, Luthfi Hakim, Evalina Herawati, I Nyoman Jaya Wistara

Makara Journal of Technology

Medium Density Fibreboard Made of Acetylated Sludge from Paper Mill. Research of using sludge as raw material for making medium density fibreboard (MDF) was useful to create additional value of sludge. The objective of the research was to evaluate physical properties, mechanical properties, and durability of MDF from acetylated sludge in 4 levels of acetate anhydride (0%, 3%, 5%, and 7%) with 3 replicates. The MDF was made using dry process. After materials were mixed with adhesives, they were pressed using hotpress under 170 oC temperature and 45 Pa pressure for 25 minutes. The size of the MDF sample was …

Cassava Pulp As A Biofuel Feedstock Of An Enzymatic Hydrolysis Proces, Djuma’Ali Djuma’Ali, Nonot Soewarno, Sumarno Sumarno, Dyah Primarini, Wahono Sumaryono

Makara Journal of Technology

Cassava pulp, a low cost solid byproduct of cassava starch industry, has been proposed as a high potential ethanolic fermentation substrate due to its high residual starch level, low ash content and small particle size of the lignocellulosic fibers. As the economic feasibility depends on complete degradation of the polysaccharides to fermentable glucose, the comparative hydrolytic potential of cassava pulp by six commercial enzymes were studied. Raw cassava pulp (12% w/v, particle sizeμm) hydrolyzed by both commercial pectinolytic (1) and amylolytic (2) enzymes cocktail, yielded 70.06% DE. Hydrothermal treatment of cassava pulp enhanced its susceptibility to enzymatic cleavageas compared to …