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Articles 1 - 30 of 205
Full-Text Articles in Engineering
Characterization Of Microstructural And Mechanical Properties Of 17-4 Ph Stainless Steel By Cold Rolled And Machining Vs. Dmls Additive Manufacturing, Pablo Moreno-Garibaldi, Melvyn Alvarez-Vera, Juan Alfonso Beltrán-Fernández, Rafael Carrera-Espinoza, Héctor Manuel Hdz-García, J. C. Díaz-Guillen, Rita Muñoz-Arroyo, Javier A. Ortega, Paul Molenda
Characterization Of Microstructural And Mechanical Properties Of 17-4 Ph Stainless Steel By Cold Rolled And Machining Vs. Dmls Additive Manufacturing, Pablo Moreno-Garibaldi, Melvyn Alvarez-Vera, Juan Alfonso Beltrán-Fernández, Rafael Carrera-Espinoza, Héctor Manuel Hdz-García, J. C. Díaz-Guillen, Rita Muñoz-Arroyo, Javier A. Ortega, Paul Molenda
Mechanical Engineering Faculty Publications and Presentations
The 17-4 PH stainless steel is widely used in the aerospace, petrochemical, chemical, food, and general metallurgical industries. The present study was conducted to analyze the mechanical properties of two types of 17-4 PH stainless steel—commercial cold-rolled and direct metal laser sintering (DMLS) manufactured. This study employed linear and nonlinear tensile FEM simulations, combined with various materials characterization techniques such as tensile testing and nanoindentation. Moreover, microstructural analysis was performed using metallographic techniques, optical microscopy, scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). The results on the microstructure for 17-4 PH DMLS stainless steel reveal …
Wire Texture C-Axis Distribution Of Strontium Ferrite/Pa-12 Extruded Filament, Gabriela Espinosa-Rodriguez, Oluwasola Arigbabowo, Jonathan Alvarado, Jitendra Tate, Wilhelmus J. Geerts
Wire Texture C-Axis Distribution Of Strontium Ferrite/Pa-12 Extruded Filament, Gabriela Espinosa-Rodriguez, Oluwasola Arigbabowo, Jonathan Alvarado, Jitendra Tate, Wilhelmus J. Geerts
Mechanical Engineering Faculty Publications and Presentations
The magnetic anisotropy of strontium ferrite (SF)/PA12 filament, a popular hard magnetic ferrimagnetic composites that is used for 3D-printing of permanent magnets, is studied by vibrating sample magnetometry. The studied filaments have a composition of SF/PA-12 thermoplastic composite with a 40% wt. ratio of SF. SF particles are non-spherical platelets with an average diameter of 1.3 um and a diameter to thickness ratio of 3. Filaments are produced by a twin-screw extruder and have a diameter of 1.5 mm. SEM images show that the SF particles are homogeneously distributed through the filament. VSM measurements on different parts of the filaments …
Assessing The Lubrication Performance Of Sunflower Oil Modified With Montmorillonite Clay (Mmt) Nanoparticles For Industrial Applications, Md Mashfiqur Rahman, Md Abu Sayeed Biswas, Laura Peña-Pará, Demófilo Maldonado- Cortés, Javier A. Ortega
Assessing The Lubrication Performance Of Sunflower Oil Modified With Montmorillonite Clay (Mmt) Nanoparticles For Industrial Applications, Md Mashfiqur Rahman, Md Abu Sayeed Biswas, Laura Peña-Pará, Demófilo Maldonado- Cortés, Javier A. Ortega
Mechanical Engineering Faculty Publications and Presentations
Because of the environmental impact and price volatility, there has been a growing concern about using petroleum-based lubricants. This issue has encouraged research into the development of biodegradable lubricants like vegetable oils. This study assessed the tribological behavior of sunflower oil modified with Montmorillonite nanoclay (MMT) as lubricant additives. A block-on-ring tribometer was used to assess the wear and friction characteristics of the nano-lubricants. A custom-made tapping torque tester was used to evaluate the nano-lubricants in a real-world application. It was found that the volumetric wear, Coefficient of Friction, and torque of the system decreased when MMT nanoparticles were added. …
Graphene Reinforced Pvdf Nanofibers Fabricated With The Forcespinning® Method For Water Desalination Applications, Elmmer A. Vera Alvarado, Md. Abdur Rahman Bin Abdus Salam, Ali Ashraf, Karen Lozano
Graphene Reinforced Pvdf Nanofibers Fabricated With The Forcespinning® Method For Water Desalination Applications, Elmmer A. Vera Alvarado, Md. Abdur Rahman Bin Abdus Salam, Ali Ashraf, Karen Lozano
Mechanical Engineering Faculty Publications and Presentations
Direct contact membrane distillation (DCMD) is a thermally driven energy and cost-efficient desalination technique where low-grade energy from solar or waste heat from plants can be used to recover fresh water from high saline water. The DCMD technique allows both the feed and permeate solutions to be in contact with the membrane, where vapor from the feed gets condensed in the permeate side once it collides with low- temperature water. Polyvinylidene fluoride (PVDF) nanofiber membranes were prepared by the ForceSpinning® method, these were later dip coated in graphene solutions prepared with different solvents. The ForceSpinning® method, unlike electrospinning, operates in …
Modelling Of A Drone To Analyze Dynamic Instabilities With Its Delivery System, Eleazar Marquez, Ivan Luna
Modelling Of A Drone To Analyze Dynamic Instabilities With Its Delivery System, Eleazar Marquez, Ivan Luna
Mechanical Engineering Faculty Publications and Presentations
In the study herein, an alternative mathematical model was developed with the intention of understanding the dynamics associated with the instabilities generated by an UAV and its delivery system, particularly the coupled nonlinearities of the system, and thus provide feedback to optimize drone design. In this regard, a Newton-Euler methodology was adopted to establish the parameters of the equations of motion of the target UAV system, which consisted of a combination of a platform and delivery system operating simultaneously. Specifically, the UAV platform was modelled as a rigid body which accounted for a total of six-degrees-of-freedom, three corresponding to the …
In-Situ Shear Exfoliation Of Graphene From Graphite Polymer Nanocomposites For Lung And Heart Motion, Md Ashiqur Rahman, Md Abdur Rahman Bin Abdus Salam, Ali Ashraf
In-Situ Shear Exfoliation Of Graphene From Graphite Polymer Nanocomposites For Lung And Heart Motion, Md Ashiqur Rahman, Md Abdur Rahman Bin Abdus Salam, Ali Ashraf
Mechanical Engineering Faculty Publications and Presentations
Graphene-based nanocomposites have become attractive for different applications such as energy storage, sensors, biomolecule detection, biomedical, healthcare, and wearable devices due to their unique mechanical, electrical, and thermal properties. However, using commercial graphene for making nanocomposite devices can be expensive, and fabricating nanocomposites can be challenging due to impurities while transferring graphene to elastomer composites. In this study, we used a simple, inexpensive in-situ shear exfoliation method to produce graphene from graphite directly within the elastomer. As the graphene in the elastomer reached beyond its percolation or threshold, electrons hop or tunnel around from one graphene flake to another. So, …
Effect Of Foot Additional Mass On The Clinical Angles Of Knee Extension Exercise, Dumitru I. Caruntu, Alfirio Trejo, Eric Rodriguez, Camila T. Alvarez B
Effect Of Foot Additional Mass On The Clinical Angles Of Knee Extension Exercise, Dumitru I. Caruntu, Alfirio Trejo, Eric Rodriguez, Camila T. Alvarez B
Mechanical Engineering Faculty Publications and Presentations
This study investigates the effect of foot additional mass on the abduction and internal rotation knee angles during knee extension exercise. Three subjects (two male and one female) performed four sets of ten repetitions of the knee extension exercise for the right leg. For the first set, the subject performed the exercise with no additional weight. For each set after, weight was added around the subject’s right foot and the subject was allowed a rest period before beginning the next set. The weights for sets 1, 2, 3, and 4 were 0.00kg (no additional weight) ,0.82kg, 1.64kg, and 2.27kg respectively. …
Computational Modelling Of A Triaxial Vibrating Sample Magnetometer, Leo Rodriguez, Arjun Sapkota, Jonathan Alvarado, Jitendra S. Tate, Wilhelmus J. Geerts
Computational Modelling Of A Triaxial Vibrating Sample Magnetometer, Leo Rodriguez, Arjun Sapkota, Jonathan Alvarado, Jitendra S. Tate, Wilhelmus J. Geerts
Mechanical Engineering Faculty Publications and Presentations
Magnetic Field Assisted Additive Manufacturing (MFAAM) enables 3D printing of magnetic materials of various shapes which exhibit a complex anisotropy energy surface containing contributions generated from different origins such as sample, particle, and agglomerate shape anisotropy, flow and field induced anisotropy, and particle crystal anisotropy. These novel magnet shapes require the need to measure the x, y, and z components of the magnetic dipole moment simultaneously to fully understand the magnetic reversal mechanism and unravel the complex magnetic anisotropy energy surface of 3D printed magnetic composites. This work aims to develop a triaxial vibrating sample magnetometer (VSM) by adding a …
Functionalized Thermoplastic Polyurethane Nanofibers: An Innovative Triboelectric Energy Generator, Julia I. Salas, Diego De Leon, Sk Shamim Hasan Abir, Mohammed Jasim Uddin, Karen Lozano
Functionalized Thermoplastic Polyurethane Nanofibers: An Innovative Triboelectric Energy Generator, Julia I. Salas, Diego De Leon, Sk Shamim Hasan Abir, Mohammed Jasim Uddin, Karen Lozano
Mechanical Engineering Faculty Publications and Presentations
A triboelectric nanogenerator (TENG) is one of the most significantly innovative microdevices for built-in energy harvesting with wearable and portable electronics. In this study, the forcespinning technology was used to synthesize a nanofiber (NF) mat-based TENG. Polyvinylidene fluoride (PVDF) membrane was used as the negative triboelectric electrode/pole, and chemically designed and functionalized thermoplastic polyurethane (TPU) was used as the positive electrode/pole for the TENG. The electronic interference, sensitivity, and gate voltage of the synthesized microdevices were investigated using chemically modified bridging of multi-walled carbon nanotubes (MWCNT) with a TPU polymer repeating unit and bare TPU-based positive electrodes. The chemical functionality …
Amplitude-Voltage Response Of Parametric Resonance Of Electrostatically Actuated Circular Membranes, Marcos Alipi, Dumitru I. Caruntu
Amplitude-Voltage Response Of Parametric Resonance Of Electrostatically Actuated Circular Membranes, Marcos Alipi, Dumitru I. Caruntu
Mechanical Engineering Faculty Publications and Presentations
This paper deals with the amplitude-voltage response of parametric resonance of electrostatically actuated MEMS circular membranes resonator for sensing applications. The system consists of a flexible circular membrane over a parallel ground plate. A soft AC voltage is applied between the MEMS membrane and ground plate to actuate the membrane near its first natural frequency. Two methods of investigation are used in this research, namely the method of multiple scales (MMS), and the reduced order model (ROM). These methods were used to solve for the voltage response of the MEMS analytically and numerically. This work also reports the effects the …
Mems Cantilever Biosensors Driven By Fringe Effect: Voltage-Amplitude Response Of Parametric Resonance, Miguel A. Martinez, Dumitru I. Caruntu
Mems Cantilever Biosensors Driven By Fringe Effect: Voltage-Amplitude Response Of Parametric Resonance, Miguel A. Martinez, Dumitru I. Caruntu
Mechanical Engineering Faculty Publications and Presentations
This paper deals with voltage-amplitude response of fringing field/effect actuated micro-electromechanical system (MEMS) cantilever beam resonator biosensors at parametric resonance. The system consists of a flexible electrode (cantilever beam) and a fixed electrode (ground plate) in parallel, connected through an AC voltage source. The electrostatic force induced is due to the parallel-plate capacitance, which is directly related to the overlapping area of the two electrodes (Palmer’s Formula). In addition, fringing field electrostatic actuation must be accounted for. This is due to the bending of electric field lines from the ground plate to the top and side walls of the cantilever …
Thermal Transport And Rheological Properties Of Hybrid Nanofluids Based On Vegetable Lubricants, Helio Ribeiro, Jaime Taha-Tijerina, Ofelia Gomez, Ever Acosta, Gabriel M. Pinto, Lorena R. C. Moraes, Guilhermino J. M. Fechine, Ricardo J. E. Andrade, Jefferson Reinoza, Victoria Padilla, Karen Lozano
Thermal Transport And Rheological Properties Of Hybrid Nanofluids Based On Vegetable Lubricants, Helio Ribeiro, Jaime Taha-Tijerina, Ofelia Gomez, Ever Acosta, Gabriel M. Pinto, Lorena R. C. Moraes, Guilhermino J. M. Fechine, Ricardo J. E. Andrade, Jefferson Reinoza, Victoria Padilla, Karen Lozano
Mechanical Engineering Faculty Publications and Presentations
Nanofluids based on vegetal oil with different wt.% of carbon nanotubes (CNT), hexagonal boron nitride (h-BN), and its hybrid (h-BN@CNT) were produced to investigate the effects of these nano-additives on the thermal conductivity and rheological properties of nanofluids. Stable suspensions of these oil/nanostructures were produced without the use of stabilizing agents. The dispersed nanostructures were investigated by SEM, EDS, XRD, and XPS, while the thermal conductivity and rheological characteristics were studied by a transient hot-wire method and steady-state flow tests, respectively. Increases in thermal conductivity of up to 39% were observed for fluids produced with 0.5 wt.% of the hybrid …
A Facile Graphene Conductive Polymer Paper Based Biosensor For Dopamine, Tnf-Α, And Il-6 Detection, Md Ashiqur Rahman, Ramendra Kishor Pal, Nazmul Islam, Robert Freeman, Francois Berthiaume, Aaron Mazzeo, Ali Ashraf
A Facile Graphene Conductive Polymer Paper Based Biosensor For Dopamine, Tnf-Α, And Il-6 Detection, Md Ashiqur Rahman, Ramendra Kishor Pal, Nazmul Islam, Robert Freeman, Francois Berthiaume, Aaron Mazzeo, Ali Ashraf
Mechanical Engineering Faculty Publications and Presentations
Paper-based biosensors are a potential paradigm of sensitivity achieved via microporous spreading/microfluidics, simplicity, and affordability. In this paper, we develop decorated paper with graphene and conductive polymer (herein referred to as graphene conductive polymer paper-based sensor or GCPPS) for sensitive detection of biomolecules. Planetary mixing resulted in uniformly dispersed graphene and conductive polymer ink, which was applied to laser-cut Whatman filter paper substrates. Scanning electron microscopy and Raman spectroscopy showed strong attachment of conductive polymer-functionalized graphene to cellulose fibers. The GCPPS detected dopamine and cytokines, such as tumor necrosis factor-alpha (TNF-α), and interleukin 6 (IL-6) in the ranges of 12.5–400 …
Multifunctional Graphene–Polymer Nanocomposite Sensors Formed By One-Step In Situ Shear Exfoliation Of Graphite, Ali Ashraf, Elizabeth Chang, Md Ashiqur Rahman, Dipannita Ghosh, Nazmul Islam, Jennifer K. Lynch-Branzoi
Multifunctional Graphene–Polymer Nanocomposite Sensors Formed By One-Step In Situ Shear Exfoliation Of Graphite, Ali Ashraf, Elizabeth Chang, Md Ashiqur Rahman, Dipannita Ghosh, Nazmul Islam, Jennifer K. Lynch-Branzoi
Mechanical Engineering Faculty Publications and Presentations
Graphene nanocomposites are a promising class of advanced materials for sensing applications; yet, their commercialization is hindered due to impurity incorporation during fabrication and high costs. The aim of this work is to prepare graphene–polysulfone (G−PSU) and graphene–polyvinylidene fluoride (G−PVDF) nanocomposites that perform as multifunctional sensors and are formed using a one-step, in situ exfoliation process whereby graphite is exfoliated into graphene nanoflakes (GNFs) directly within the polymer. This low-cost method creates a nanocomposite while avoiding impurity exposure since the raw materials used in the in situ shear exfoliation process are graphite and polymers. The morphology, structure, thermal properties, and …
Regulating The Size And Assembled Structure Of Graphene Building Blocks For High-Performance Silicon Nanocomposite Anodes, Bo Nie, David Sanchez, Mataz Alcoutlabi, Tengxiao Liu, Saurabh Basu, Soundar Kumara, Gongkai Wang, Hongtao Sun
Regulating The Size And Assembled Structure Of Graphene Building Blocks For High-Performance Silicon Nanocomposite Anodes, Bo Nie, David Sanchez, Mataz Alcoutlabi, Tengxiao Liu, Saurabh Basu, Soundar Kumara, Gongkai Wang, Hongtao Sun
Mechanical Engineering Faculty Publications and Presentations
Silicon-based composites have received significant interest as a high-capacity anode material for high-performance lithium-ion batteries. However, the large volume change during prolonged charge/discharge cycles, poor electric conductivity, and unstable solid electrolyte interface of the Si electrodes lead to performance degradations, such as fast capacity decay and low coulombic efficiency (CE). It's promising but challenging to fabricate Si-based composite anodes with a high Si active material, which enables high energy density, high-rate capability, and good cycling stability. Herein, the size effect of mechanically robust and highly conductive graphene sheets was investigated to effectively regulate the charge transport kinetics, volume changes, first …
Effect Of Nanoparticle Loading And Magnetic Field Application On The Thermodynamic, Optical, And Rheological Behavior Of Thermoresponsive Polymer Solutions, Christopher A. P. Neal, Grace V. Kresge, Michelle C. Quan, Valeria León, Nondumiso O. Chibambo, Michelle A. Calabrese
Effect Of Nanoparticle Loading And Magnetic Field Application On The Thermodynamic, Optical, And Rheological Behavior Of Thermoresponsive Polymer Solutions, Christopher A. P. Neal, Grace V. Kresge, Michelle C. Quan, Valeria León, Nondumiso O. Chibambo, Michelle A. Calabrese
Mechanical Engineering Faculty Publications and Presentations
Although processing via external stimuli is a promising technique to tune the structure and properties of polymeric materials, the impact of magnetic fields on phase transitions in thermoresponsive polymer solutions is not well-understood. As nanoparticle (NP) addition is also known to impact these thermodynamic and optical properties, synergistic effects from combining magnetic fields with NP incorporation provide a novel route for tuning material properties. Here, the thermodynamic, optical, and rheological properties of aqueous poly(N-isopropyl acrylamide) (PNIPAM) solutions are examined in the presence of hydrophilic silica NPs and magnetic fields, individually and jointly, via Fourier-transform infrared spectroscopy (FTIR), magneto-turbidimetry, …
Learning In Transition: Developing And Employing Pedagogical Supports To Enhance Student Learning In Engineering Education, Eleazar Marquez, Samuel Garcia
Learning In Transition: Developing And Employing Pedagogical Supports To Enhance Student Learning In Engineering Education, Eleazar Marquez, Samuel Garcia
Mechanical Engineering Faculty Publications and Presentations
Scholarly research indicates that classroom environment and conditions influence the degree of student learning, levels of engagement, and overall success in engineering education. In the wake of COVID-19, educational institutions transitioned to fully online delivery that disrupted traditional and effective channels of communication enacted in classroom contexts. For a substantial number of faculty members, this rapid transition to a fully remote instructional context marked the start a novel style of teaching and learning environment, a grand departure from the traditional, direct face-to-face setting. Such rapid and disruptive change required creative solutions to routinized instructional practices and compelling faculty to adjust …
Keeping Calm And Staying Balanced: Exploring The Academic Pressures Faced By Engineering Students To Attain High Grades And Their Impact On Mental Health, Eleazar Marquez, Samuel Garcia
Keeping Calm And Staying Balanced: Exploring The Academic Pressures Faced By Engineering Students To Attain High Grades And Their Impact On Mental Health, Eleazar Marquez, Samuel Garcia
Mechanical Engineering Faculty Publications and Presentations
Studies reveal that grades have a short-term impact on students’ self-efficacy, motivation, and decision making. Earning high grades has become a focal point for engineering students to secure three types of opportunities: internships, post-graduation employment, and graduate school acceptance. Nonetheless, the desire to attain a competitive grade-point-average may lead to negative psychosocial effects such as increased mental exertion, physical exhaustion, anxiety, and overall lack of work-life balance. In this paper, the authors extend their prior study on the impact of grades in engineering education. The first study was conducted in the spring of 2019 at a tier one, small private …
Bend And Not Break: Examining Hispanic Engineering Student's Academic Challenges During Covid-19, Eleazar Marquez, Samuel Garcia
Bend And Not Break: Examining Hispanic Engineering Student's Academic Challenges During Covid-19, Eleazar Marquez, Samuel Garcia
Mechanical Engineering Faculty Publications and Presentations
Student success in higher education remains an area of interest, particularly for underrepresented minorities. Studies reveal that while Latino college enrollment has increased, retention rates continue to be an ongoing struggle. Several factors that attribute to such low rates include academic self-concept, family support, cognitive mapping, managing resources, background characteristics, and separation and maintenance of family ties. In the wake of COVID-19, most institutions responded by terminating in-person instruction, mandating to seek off-campus housing, and shifting to a fully remote context. As such, students were unable to utilize campus resources and engage in established educational campus practices. In this research …
Leveling The Playing Field: Enacting Equitable Pedagogy To Teach Rigid Body Dynamics, Eleazar Marquez, Samuel Garcia
Leveling The Playing Field: Enacting Equitable Pedagogy To Teach Rigid Body Dynamics, Eleazar Marquez, Samuel Garcia
Mechanical Engineering Faculty Publications and Presentations
Research examining the quality of engineering programs across different instructions of learning has revealed that no two programs are alike. Each program has unique and distinctive features that influence the quality and rigor of education that students receive. Institutional culture, leadership, faculty preparedness, funding and many other factors influence program quality. Additionally, researchers have also noted that many institutional gaps and equity related issues are persistent and troublesome facets that further exacerbate the academic gaps in STEM education. It is within this context, that students attending top tier universities will likely have remarkedly vast academic experiences in terms of level …
Board 399: The Freshman Year Innovator Experience (Fyie): Bridging The Urm Gap In Stem, Noe Vargas Hernandez, Arturo A. Fuentes, Karen Lozano, Javier A. Ortega, Eleazar Marquez
Board 399: The Freshman Year Innovator Experience (Fyie): Bridging The Urm Gap In Stem, Noe Vargas Hernandez, Arturo A. Fuentes, Karen Lozano, Javier A. Ortega, Eleazar Marquez
Mechanical Engineering Faculty Publications and Presentations
The project focuses on increasing “effective STEM education and broadening participation” in underrepresented minority STEM students at the University of Texas Rio Grande Valley (UTRGV) to successfully face academic and professional challenges, recently exacerbated by the COVID-19 pandemic. The Freshman Year Innovator Experience proposes the development of self-transformation skills in freshman mechanical engineering students to successfully face academic and professional challenges exacerbated by the COVID-19 pandemic while working on two parallel projects of technical design innovation and academic career pathways. The authors will present the work in progress and preliminary results from a pilot implementation of the Freshman Year Innovator …
Feasibility Analysis Of A Wave Powered Autonomous Underwater Vehicle, Yingchen Yang, Erick Martinez
Feasibility Analysis Of A Wave Powered Autonomous Underwater Vehicle, Yingchen Yang, Erick Martinez
Mechanical Engineering Faculty Publications and Presentations
An autonomous underwater vehicle (AUV) powered by renewable energy would enable it to extend endurance and forward presence with no logistics tail for fuel. A wave powered concept AUV is proposed and analyzed for this purpose. The AUV is in a torpedo shape and employs a fully hull-encapsulated mass-spring-damper system as its power take-off (PTO) unit. While in the recharging mode, the AUV surfaces and converts wave energy for electricity. Considering the AUV of a common size, our analysis indicates that resonance of the AUV and/or its PTO, to be excited by ocean waves, becomes impossible in typical ocean conditions. …
Recent Advances In Centrifugal Spinning And Their Applications In Tissue Engineering, Shaik Merkatur Hakim Marjuban, Musfira Rahman, Syeda Sharmin Duza, Mohammad Boshir Ahmed, Dinesh K. Patel, Md Saifur Rahman, Karen Lozano
Recent Advances In Centrifugal Spinning And Their Applications In Tissue Engineering, Shaik Merkatur Hakim Marjuban, Musfira Rahman, Syeda Sharmin Duza, Mohammad Boshir Ahmed, Dinesh K. Patel, Md Saifur Rahman, Karen Lozano
Mechanical Engineering Faculty Publications and Presentations
Over the last decade, researchers have investigated the potential of nano and microfiber scaffolds to promote wound healing, tissue regeneration, and skin protection. The centrifugal spinning technique is favored over others due to its relatively straightforward mechanism for producing large quantities of fiber. Many polymeric materials have yet to be investigated in search of those with multifunctional properties that would make them attractive in tissue applications. This literature presents the fundamental process of fiber generation, and the effects of fabrication parameters (machine, solution) on the morphologies such as fiber diameter, distribution, alignment, porous features, and mechanical properties. Additionally, a brief …
Automatic Dispersion, Defect, Curing, And Thermal Characteristics Determination Of Polymer Composites Using Micro-Scale Infrared Thermography And Machine Learning Algorithm, Md Ashiqur Rahman, Mirza Masfiqur Rahman, Ali Ashraf
Automatic Dispersion, Defect, Curing, And Thermal Characteristics Determination Of Polymer Composites Using Micro-Scale Infrared Thermography And Machine Learning Algorithm, Md Ashiqur Rahman, Mirza Masfiqur Rahman, Ali Ashraf
Mechanical Engineering Faculty Publications and Presentations
Infrared thermography is a non-destructive technique that can be exploited in many fields including polymer composite investigation. Based on emissivity and thermal diffusivity variation; components, defects, and curing state of the composite can be identified. However, manual processing of thermal images that may contain significant artifacts, is prone to erroneous component and property determination. In this study, thermal images of different graphite/graphene-based polymer composites fabricated by hand, planetary, and batch mixing techniques were analyzed through an automatic machine learning model. Filler size, shape, and location can be identified in polymer composites and thus, the dispersion of different samples was quantified …
Development Of An Improved Mathematical Representation Which Captures The Nonlinear Dynamic Behavior Of A Drill-String Assembly, Eleazar Marquez
Development Of An Improved Mathematical Representation Which Captures The Nonlinear Dynamic Behavior Of A Drill-String Assembly, Eleazar Marquez
Mechanical Engineering Faculty Publications and Presentations
In this study, an improved mathematical representation of a drill-string assembly is developed to provide an alternative assessment on vibration irregularities proliferating downhole due to bit-rock interference. Lateral vibrations receive particular attention due to their high frequency content which alter the dynamic response of the drill-string, instigate casing damage, and impede optimal penetration rates. The response of the drill-string is captured by synthesizing compatible stationary bit excitations, via an auto-regressive digital filter, and implementing Monte Carlo simulation, while the power spectral density function is approximated to elucidate the dynamic characteristics during drilling. Formulating adequate physical parameters for the equation of …
Quadcopter Control Using Single Network Adaptive Critics, Alberto Velazquez, Lei Xu, Tohid Sardarmehni
Quadcopter Control Using Single Network Adaptive Critics, Alberto Velazquez, Lei Xu, Tohid Sardarmehni
Mechanical Engineering Faculty Publications and Presentations
In this paper, optimal tracking control is found for an inputaffine nonlinear quadcopter using Single Network Adaptive Critics (SNAC). The quadcopter dynamics consists of twelve states and four controls. The states are defined using two related reference frames: the earth frame, which describes the position and angles, and the body frame, which describes the linear and angular velocities. The quadcopter has six outputs and four controls, so it is an underactuated nonlinear system. The optimal control for the system is derived by solving a discrete-time recursive Hamilton-Jacobi-Bellman equation using a linear in-parameter neural network. The neural network is trained to …
A Probabilistic Analysis In Vibration-Assisted Drilling To Measure Dynamic Behavior During Drilling And Understand Risk Factors, Eleazar Marquez, Samuel Garcia
A Probabilistic Analysis In Vibration-Assisted Drilling To Measure Dynamic Behavior During Drilling And Understand Risk Factors, Eleazar Marquez, Samuel Garcia
Mechanical Engineering Faculty Publications and Presentations
In this paper, a mathematical representation is proposed to further understand the dynamic behavior and risk factors associated with vibration-assisted drilling (VAD) technology. The proposed Timoshenko beam model, which characterizes VAD technology, consists of two passive, counter-rotating coaxial rotors operating simultaneously, subjected to a stochastic excitation. In this regard, a finite element technique was incorporated to determine the physical parameters of the governing equation of motion, where the shear and rotary effects, as well as the gyroscopic couples generated perpendicular to the axis of rotation, were accounted for. Further, the relative velocity between the coaxial rotors was accounted in the …
Estimation Of The Response, Power Spectra, And Whirling Patterns Generated From Mud Circulating Along The Annulus During Drilling Procedures: An Alternative Mathematical Representation Via Finite Element Modelling, Eleazar Marquez
Mechanical Engineering Faculty Publications and Presentations
In this study, an alternative mathematical representation of a drill-string is proposed to provide an alternative assessment on BHA dynamic alterations. Lateral vibrations remain the focal point of drill-string breakdowns given their high frequency characterization and ability to deviate perforation trajectories from the subsurface target. In this paper, the proposed model consists of an anisotropic rotor subjected to distinct RPMs, an axial force, and a bidirectional harmonic excitation with specified amplitude and assorted duration to simulate annulus motion generated from the mud fluid. In this regard, Euler-Bernoulli beam theory was adopted to establish a complete MDOF mathematical expression and thus …
Non-Destructive Infrared Thermographic Curing Analysis Of Polymer Composites, Md Ashiqur Rahman, Javier Becerril, Dipannita Ghosh, Nazmul Islam, Ali Ashraf
Non-Destructive Infrared Thermographic Curing Analysis Of Polymer Composites, Md Ashiqur Rahman, Javier Becerril, Dipannita Ghosh, Nazmul Islam, Ali Ashraf
Mechanical Engineering Faculty Publications and Presentations
Infrared (IR) thermography is a non-contact method of measuring temperature that analyzes the infrared radiation emitted by an object. Properties of polymer composites are heavily influenced by the filler material, filler size, and filler dispersion, and thus thermographic analysis can be a useful tool to determine the curing and filler dispersion. In this study, we investigated the curing mechanisms of polymer composites at the microscale by capturing real-time temperature using an IR Thermal Camera. Silicone polymers with fillers of Graphene, Graphite powder, Graphite flake, and Molybdenum disulfide (MoS2) were subsequently poured into a customized 3D printed mold for …
Fluid Mechanics Of Air Recycling And Filtration For Indoor Airborne Transmission, K. A. Krishnaprasad, J. S. Salinas, Nadim Zgheib, S. Balachandar
Fluid Mechanics Of Air Recycling And Filtration For Indoor Airborne Transmission, K. A. Krishnaprasad, J. S. Salinas, Nadim Zgheib, S. Balachandar
Mechanical Engineering Faculty Publications and Presentations
We present a statistical framework to account for effects of recycling and filtration in ventilation systems for the estimation of airborne droplet nuclei concentration in indoor spaces. We demonstrate the framework in a canonical room with a four-way cassette air-conditioning system. The flow field within the room is computed using large eddy simulations for varying values of air changes per hour, and statistical overloading is used for droplet nuclei, which are tracked with a Langevin model accounting for sub-grid turbulence. A key element is to break up the path that a virus-laden droplet nucleus can take from the time it …