Engineering Science and Materials Commons^™

Effects Of Gravity On The Acceleration And Pair Statistics Of Inertial Particles In Homogeneous Isotropic Turbulence, H. Parishani, O. Ayala, B. Rosa, L.-P. Wang, W. W. Grabowski

Engineering Technology Faculty Publications

Within the context of heavy particles suspended in a turbulent airflow, we study the effects of gravity on acceleration statistics and radial relative velocity (RRV) of inertial particles. The turbulent flow is simulated by direct numerical simulation (DNS) on a 256³ grid and the dynamics of O(10⁶) inertial particles by the point-particle approach. For particles/droplets with radius from 10 to 60 µm, we found that the gravity plays an important role in particle acceleration statistics: (a) a peak value of particle acceleration variance appears in both the horizontal and vertical directions at a particle Stokes number …

Context Aware Textual Entailment, Soha Arab-Khazaeli

LSU Doctoral Dissertations

In conversations, stories, news reporting, and other forms of natural language, understanding requires participants to make assumptions (hypothesis) based on background knowledge, a process called entailment. These assumptions may then be supported, contradicted, or refined as a conversation or story progresses and additional facts become known and context changes. It is often the case that we do not know an aspect of the story with certainty but rather believe it to be the case; i.e., what we know is associated with uncertainty or ambiguity. In this research a method has been developed to identify different contexts of the input raw …

Microindentation Of Bi57in26sn17 Lead-Free Alloy, Ruiting Zhao

Theses and Dissertations--Chemical and Materials Engineering

There is great need to understand the mechanical properties of lead-free alloys—an alternative of lead-based alloys—to address the environmental problems associated with the use of lead-based materials in microelectronics. In this work, the microstructures of Bi57In26Sn17 lead-free alloy were examined using Optical Microscopy and Energy Dispersive X-ray Spectroscopy analysis. The micro-indentation technique was used to study the mechanical properties of Bi57In26Sn17 lead-free alloy. The experimental results of the hardness and contact modulus were presented and discussed. Local creep during the indentation was observed from the load-displacement curves. The Vickers hardness (HV) increases with the decrease of the indentation depth, suggesting …

Developing Co-Current And Counter-Current Spray Drying Computational Fluid Dynamics (Cfd) Simulation Studies To Predict The Quality Of Microencapsulated Fish Oil With Egg White Hydrolysates Powders, Kevin Estuardo Mis Solval

LSU Doctoral Dissertations

Eggs are an excellent source of high quality protein containing all essential amino acids (EAA) including leucine. Food-grade protein hydrolysates can enhance the growth of lactic acid bacteria (LAB). Thermal degradation of bioactives normally occurs during microencapsulation by spray drying. Spray drying modeling using computational tools is essential to engineer new food powders and to minimize and thermal degradation of bioactives. The first chapter of this work discusses the optimization of an enzymatic process in terms of reaction temperature, pH, enzyme:substrate ratio, and reaction time using a response surface methodology (RSM) to produce food-grade protein hydrolysates from egg whites (EWH). …

Binder Jet Additive Manufacturing Of Stainless Steel-Hydroxyapatite Bio-Composite, Don Suranga Dhanushka Uduwage

All Graduate Theses, Dissertations, and Other Capstone Projects

This study was conducted to create a bio-composite with a porous structure using the binder-jet printing additive manufacturing process. The samples were printed by changing the parameters such as layer thickness, roller speed, sintering time and sintering temperature of the X1-Lab binder jet additive manufacturing printer. The samples were printed 80% stainless steel 316 mixed with 20% Calcium Phosphate Tribasic by volume. Eight experiments were attempted to print according to the fractional factorial design of experiment. The effects of changing parameters on the mechanical properties of the new bio-composite was tested using ASTM E-09 compressive strength standards. The compression testing …

Risk-Based Wind Loss And Mitigation For Residential Wood Framed Construction, Fatemeh Orooji

LSU Doctoral Dissertations

As a result of increasing windstorm losses in the United States over the past 50 years, a variety of residential wind hazard mitigation methods have been suggested. Mitigation undoubtedly reduces windstorm losses; however, the expected economic risk reduction of mitigation practices over the life of the building depends on the building characteristics (i.e., capacity) and the intensity and occurrence of wind speeds (i.e., demand). Effective decision making requires estimation of potential future losses based on many variables. Many models, primarily mechanics-based simulation models, have been developed to predict building damage from wind events; however; fewer models of economic loss have …

Image-Based Modeling Of Porous Media Using Fem And Lagrangian Particle Tracking, Paula Cysneiros Sanematsu

LSU Doctoral Dissertations

The study of fundamental flow and transport processes at the pore scale is essential to understanding how the mechanisms affect larger, field-scale, processes that occur in oil and gas recovery, groundwater flow, contaminant transport, and CO2 sequestration. Pore-scale imaging and modeling is one of the techniques used to investigate these fundamental mechanisms. Although extensive development of pore-scale imaging and modeling has occurred recently, some areas still need further advances. In this work, we address two areas: (1) imaging of bulk proppants and proppant-filled fractures under varying loading stress and flow simulation in these systems and (2) nanoparticle (NP) transport modeling …

Constitutive Modeling And Experiments For The Micro And Nano Behaviors In Metals, Cheng Zhang

LSU Doctoral Dissertations

This work addresses the micro- and nano-behaviors in metals through constitutive modeling and experiments. The size effect encountered during nanoindentation experiments, which is known as indentation size effect (ISE), is investigated for metal materials. The ISE is believed to be related with the strain gradient at small indentation depths. Geometrically necessary dislocations (GNDs) are formed in order to accommodate the strain gradient, which results in the increase in the material hardness. The grain boundaries in polycrystalline materials play an important role on the material hardness during nanoindentation experiments as there is a soften-hardening segment in the curve of hardness as …

Influence Of Spatial Variations Of Railroad Track Stiffness And Material Inclusions On Fatigue Life, Celestin Nkundineza

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Railroad transportation is very important for economic growth and effective maintenance is one critical factor for its economic sustainability. The high repetitive forces from a moving railcar induce cyclic stresses that lead to rail bending and potential deterioration due to fatigue crack initiation and propagation. Previous research for prediction of fatigue life has been done under the assumptions of a uniform track bed and a homogeneous rail. However the spatial variation of the track stiffness is expected to increase the maximum stresses in the rail and, therefore, accelerate the fatigue process. The research described in this dissertation is focused on …

A Study To Evaluate Non-Uniform Phase Maps In Shape Memory Alloys Using Finite Element Method, Naren Motte

Theses and Dissertations

The unique thermo-mechanical behavior of Shape Memory Alloys (SMAs), such as their ability to recover the original shape upon heating or being able to tolerate large deformations without undergoing plastic transformations, makes them a good choice for actuators.

This work studies their application in the aerospace and defense industries where SMA components can serve as release mechanisms for gates of enclosures that have to be deployed remotely. This work provides a novel approach in evaluating the stress and heat induced change of phase in a SMA, in terms of the transformation strain tensor. In particular, the FEA tool

ANSYS has …

Time-Resolved Investigations Of Continuous Flow Synthesis Of Nanomaterials And Catalysis Using Millifluidic Reactors For Biomass Conversion Reactors, Chelliah V Navin

LSU Doctoral Dissertations

Millifluidics can be used as a simple tool and convenient platform to perform in-situ investigations on nanoparticles synthesis to generate real-time information in a continuous flow fashion. These investigations can be used to observe the relationship between the structure and performance of nanoparticles for catalytic applications as a function of space and time. These improvements in nanoparticles research offer unique advantages to develop catalysts with molecular strategies. In order to showcase these advantages of the millifluidic reactors, here we: A. Extensively covered a complete literature review on Lab-on-a-chip devices for gold nanoparticle synthesis and as a catalyst support for continuous …

Release, Stability And Functionality Of Nanodelivered Hydrophobic (Lutein And Beta-Carotene) And Hydrophilic (Folic Acid) Antioxidants Using Zein Nanoparticles, Thanida Chuacharoen

LSU Doctoral Dissertations

Nanodelivery systems enable innovations that can benefit foods and human health on a large scale in the coming years. The instabilities of antioxidants during food processing and during digestion are drawbacks that can be successfully addressed by nanoentrapment. This research provided technical strategies to synthesize zein nanoparticles loaded with hydrophobic/hydrophilic antioxidants, and to study the release profiles and physical stability of nanocarriers and chemical stability of entrapped bioactives under on-shelf and GI conditions. The results supported the potential of zein nanoparticles stabilized by surfactants to improve chemical stability of entrapped lutein, and to slowly release lutein under PBS conditions. Same …

Platinum Hollow Nanospheres With Different Sizes: Controllable Synthesis And Electrocatalytic Oxidation Toward Methanol, Xuan Lin, Mei-Qin Cheng, Zhong-Jin Shang, Ting Xiong, Xian-Tu Zhang, Wei Tian, Jian-Yun Lin, Qi-Ling Zhong, Bin Ren

Journal of Electrochemistry

The selenium (Se) templates and hollow platinum (Pthollow) nanospheres with different sizes were controllably synthesized by adjusting the concentration of sodium dodecyl sulphonate (SDSN) (CSDSN, μmol·L-1) which was used as a surfactant. Accordingly, the Pthollow nanospheres modified glassy carbon (GC) electrode (Pthollow/GC) was prepared. The morphology and composition of Pthollow nanospheres were characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), energy dispersive X-ray spectroscopy (EDX), high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) and X-ray diffraction (XRD) techniques. The electrocatalytic activities of Pthollow/GC and electrodeposited Pt nanoparticles modified glassy carbon electrode (Ptnano/GC) toward methanol oxidation …

Comparison In Factors Affecting Electrochemical Properties Of Thermal-Reduced Graphene Oxide For Supercapacitors, Peng Xiao, Da-Hui Wang, Jun-Wei Lang

Journal of Electrochemistry

In this paper, thermal-reduced graphene oxide (T-RGO) materials are synthesized by modified Hummer’s method, followed by thermal reduction under argon atmosphere at different temperatures. Electrochemical investigations show that, for T-RGO electrodes, good electrical conductivity is necessary and the surface functional groups play more significant role than the specific surface area in determining the electrochemical capacitance. The T-RGO obtained at 900 °C (T-RGO900) with a relatively high Brunauer-Emmett-Teller (BET) surface area (314 m²·g^-1) and a high electrical conductivity (2421 S·m^-1) shows a low specific capacitance of 56 F·g^-1. In comparison, the T-RGO obtained …

Nafion/Thionine/Platinum Nanowires-Modified Electrode For Electrocatalyzing Glucose, Yu-Ping Lin, You-Xiu Lin, Qian Zhou, Dian-Ping Tang

Journal of Electrochemistry

A new amperometric biosensor based on Nafion, thionine and latinum nanowires was developed for sensitive detection of glucose. Initially, positively charged thionine molecules were immobilized onto the surface of Nafion-modified glassy carbon electrode through the interaction between -SO₃^- and -NH₃⁺, and glucose oxidase was then assembled on the modified electrode by using platinum nanowires as the cross-linkage. The preparation process was characterized by using cyclic voltammetry. Two enzymatic biosensors modified with and without platinum nanowires were used for the detection of glucose, and the improved analytical properties were obtained with platinum nanowires. Experimental results indicated …

Synthesis Of Namnpo4 By Spraying Drying-High Temperature Sintering And Its Electrochemical Performance, Xiao-Chen Lin, Xiao-Biao Wu, Xu Hou, Yong Yang

Journal of Electrochemistry

As a cathode material for sodium ion batteries, NaMnPO₄/C nanocomposite is successfully synthesized by the combination of spraying drying and high temperature sintering methods. The crystal structure of the as-synthesized phosphate material is confirmed as the natrophilite NaMnPO₄, which possesses orthorhombic symmetry and Pmnb space group. It is shown that the precursors are hollow spherical particles and the obtained product consists of micro-scaled secondary particles, which are composed of NaMnPO₄ nanocrystallites (tens of nanometres) and amorphous carbon networks. The ionic and electronic conductivities of NaMnPO₄ are both effectively enhanced with the help of this …

One-Step Synthesis Of Pani/Nihcf Hybrid Film Using Unipolar Pulse Electrodeposition And Its Electrocatalytic Reduction Performance For H2O2 Detection, Sen-Liang Liao, Xiu-Min Li, Xiao-Gang Hao, Yan-Hong Wang, Chun-Feng Xue, Yong-Hong Wang

Journal of Electrochemistry

Organic–inorganic hybrid films composed of polyaniline/nickel hexacyanoferrate (PANI/NiHCF) were fabricated on platinum substrates using unipolar pulse one-step electrodeposition. The deposition mechanism of hybrid film was proposed: Due to high potential of unipolar pulse electrodeposition, which avoided the reduction of Fe(CN)₆^3-, the films with high electrocatalytic property and “insoluble” form of NiHCF were achieved. The morphology and composition of PANI/NiHCF hybrid film were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and Fourier transform infrared spectroscopy (FT-IR). The effect of pulse potential on the electrochemical performance of hybrid film was investigated in detail. Results showed that …

Electrochemical Applications Of Single-Walled Carbon Nanohorns, Su-Ping Li, Huai-Min Guan, Shu-Yun Zhu, Muhammad Rehan Hassan Shah Gilani, Saima Hanif, Guo-Bao Xu, Yue-Jin Tong

Journal of Electrochemistry

Single-wall carbon nanohorns (SWCNHs) have unique properties, such as a large specific surface area, good electrical conductivity and biocompatibility. It has been widely utilized in many fields. In the present review, the progress in electrochemistry study of SWCNHs has been summarized and the future research trends have been proposed.

Direct Electrochemistry And Glucose Biosensing Of Glucose Oxidase-Gold Nanoparticles Composite Synthesized By Enzyme Method, Fang He, Xiao-Li Qin, Ying-Chun Fu, Chao Chen, Qing-Ji Xie, Shou-Zhuo Yao

Journal of Electrochemistry

Glucose oxidase (GOx)-gold nanoparticles (AuNPs) composite was synthesized by the one-pot enzyme reaction in the mixture solution of NaAuCl₄, GOx and glucose, and a Nafion/GOx-AuNPs/glassy carbon electrode was fabricated by the cast-coating method to examine the direct electrochemistry of GOx and the biosensing performance on this electrode. Such a GOx-AuNPs composite showed good direct-electrochemistry activity and bioactivity of GOx, probably because the enzyme-mediated AuNPs are close to the redox active centers of GOx. This enzyme electrode exhibited a linear amperometric response to glucose concentration (0.54 mmol·L^-1) at -0.4 V (vs. SCE), and a detection limit of …

Density Functional Theory Study On The Structures Of Solvent-Ion In The Electrolyte Of Lithium Ion Battery, Li-Dan Xing, Ru Yang, Xian-Wen Tang, Wen-Na Huang, Qi-Feng Liu, Qi-Peng Yu, Wei-Shan Li

Journal of Electrochemistry

In this work, the possible structures of solvent-ion complex, resulting from the electrostatic interaction in the propylene carbonate (PC) base electrolyte of lithium ion battery, have been investigated using the density functional theory. The calculated results show that the structure of solvent-ion complex depends on the solvent number. In the PC base electrolyte, maximum number of PC solvents that coexist in the Li⁺-solvent sheath is four. Additionally, the salt anion exists in a complex with the positively charged alkyl group of PC rather than in a free state. The calculated results give a good explanation to the reported …