Engineering Commons^™

Stabilized Wide Bandgap MapbbrXI3– X Perovskite By Enhanced Grain Size And Improved Crystallinity, Miao Hu, Cheng Bi, Yongbo Yuan, Yang Bai, Jinsong Huang

Department of Mechanical and Materials Engineering: Faculty Publications

Methylammonium lead trihalide perovskite (MAPbX₃, where MA is methylammonium, and X is a halide)-based solar cells have been intensively investigated recently, with the demonstrated certified solar power conversion efficiency (PCE) exceeding 20%. To further boost the PCE to beyond the Schockley–Queisser limit, tandem structured solar cells have been investigated based on integrating MAPbX₃ and low bandgap solar cells. However, the efficiency of the two-terminal integrated perovskite-silicon tandem cells is still low. The best reported efficiency of 13.7% for this type of tandem cells is far smaller than the individual cells yet, partially due to the limited performance …

Ultrahigh Sensitivity Of Methylammonium Lead Tribromide Perovskite Single Crystals To Environmental Gases, Hong-Hua Fang, Sampson Adjokatse, Haotong Wei, Jie Yang, Graeme R. Blake, Jinsong Huang, Jacky Even, Maria Antonietta Loi

Department of Mechanical and Materials Engineering: Faculty Publications

One of the limiting factors to high device performance in photovoltaics is the presence of surface traps. Hence, the understanding and control of carrier recombination at the surface of organic-inorganic hybrid perovskite is critical for the design and optimization of devices with this material as the active layer. We demonstrate that the surface recombination rate (or surface trap state density) inmethylammonium lead tribromide (MAPbBr3) single crystals can be fully and reversibly controlled by the physisorption of oxygen and water molecules, leading to a modulation of the photoluminescence intensity by over two orders of magnitude.We report an unusually low surface recombination …

Pulsed Laser Cutting Of Magnesium-Calcium For Biodegradable Stents, M. P. Sealy, Y. B. Guo, J. F. Liu, C. Li

Department of Mechanical and Materials Engineering: Faculty Publications

There is growing interests in the use of biodegradable magnesium implants for cardiovascular and pulmonary applications such as stents. Magnesium is a metal that has the ability to gradually dissolve and absorb into the human body after implantation. There is very little work discussing the relationship between process parameters and cut quality of magnesium stents by laser cutting. The objective of this research is to determine the effect of laser cutting conditions including peak laser power and cutting speed of a millisecond range pulsed laser on kerf geometry, surface topography, surface roughness, and microstructure. An assessment on the experimental work …

Impact Of Patient Factors On Operative Duration During Laparoscopic Cholecystectomy: Evaluation From The National Surgical Quality Improvement Program Database, Bethany Rose Lowndes, Cornelius A. Thiels, Elizabeth B. Habermann, Juliane Bingener, M. Susan Hallbeck, Denny Yu

Department of Mechanical and Materials Engineering: Faculty Publications

BACKGROUND: Patient factors impact laparoscopic cholecystectomy (LC) difficulty, specifically operative duration. This study quantifies the impact of patient factors on LC duration.

METHODS: The national surgery database (American College of Surgeons National Surgical Quality Improvement Program) was reviewed for all elective LC for biliary colic from 2005 to 2013. Multivariate general linear model and logistic regression were used to evaluate patient factors as predictors of operative duration greater than 60 minutes, adjusted for resident involvement and cholangiography.

RESULTS: A total of 24,099 LC met inclusion criteria. Regression analysis found procedure duration greater than 60 minutes was less likely for patients …

A Comparative Study On Machining Capabilities Of Wet And Dry Nanoscale Electro-Machining, Muhammad P. Jahan, Kamlakar P. Rajurkar, Ajay P. Malshe

Department of Mechanical and Materials Engineering: Faculty Publications

Presently, the nano scale electro-machining (nano-EM) process has been demonstrated in both the liquid and air dielectric mediums, which are known as wet and dry nano-EM respectively. In the current study, two important aspects of the nano-EM have been investigated: the minimum possible feature dimension and mass fabrication capability of nano-EM. Firstly, the investigation has been done on the capability of machining graphene at atomic scale with focus on obtaining smallest possible nano-feature using the wet nano-EM. Secondly, the ability of the nano-EM process for the fabrication of arrays of nano-holes has been investigated using dry nano-EM. It was found …

Bioink Properties Before, During And After 3d Bioprinting, Katja Holzl, Shengmao Lin, Liesbeth Tytgat, Sandra Van Vlierberghe, Linxia Gu, Aleksandr Ovsianikov

Department of Mechanical and Materials Engineering: Faculty Publications

Bioprinting is a process based on additive manufacturing from materials containing living cells. These materials, often referred to as bioink, are based on cytocompatible hydrogel precursor formulations, which gel in a manner compatible with different bioprinting approaches. The bioink properties before, during and after gelation are essential for its printability, comprising such features as achievable structural resolution, shape fidelity and cell survival. However, it is the final properties of the matured bioprinted tissue construct that are crucial for the end application. During tissue formation these properties are influenced by the amount of cells present in the construct, their proliferation, migration …

Development Of A Synthetic Gene Network To Modulate Gene Expression By Mechanical Forces, Zoltan Kis, Tania Rodin, Asma Zafar, Zhangxing Lai, Grace Freke, Oliver Fleck, Armando Del Rio Hernandez, Leila Towhidi, Ryan M. Pedrigi, Takayuki Homma, Rob Krams

Department of Mechanical and Materials Engineering: Faculty Publications

The majority of (mammalian) cells in our body are sensitive to mechanical forces, but little work has been done to develop assays to monitor mechanosensor activity. Furthermore, it is currently impossible to use mechanosensor activity to drive gene expression. To address these needs, we developed the first mammalian mechanosensitive synthetic gene network to monitor endothelial cell shear stress levels and directly modulate expression of an atheroprotective transcription factor by shear stress. The technique is highly modular, easily scalable and allows graded control of gene expression by mechanical stimuli in hard-to-transfect mammalian cells. We call this new approach mechanosyngenetics. To insert …

Portable Camera Aided Simulator (Portcas) For Minimally Invasive Surgical Training, Ka-Chun Sui, Carl Nelson, Mohsen Zahiri, Dmitry Oleynikov

Department of Mechanical and Materials Engineering: Faculty Publications

The present disclosure is directed to a system and method for surgical training with low cost, reusable materials and a highly customizable virtual environment for skill-building. According to various embodiments, a surgical training tool is usable in conjunction with a support structure configured to at least partially constrain the tool movement. Meanwhile, the tool is tracked in real-time with off-tool detectors to generate a tool path driving a virtual rendering of the surgical training tool in an operative environment. The virtual rendering may be visually observable via a display device and may include a customizable and/or selectable operative environment with …

Secondary Pool Boiling Effects, C. Kruse, A. Tsubaki, C. A. Zuhlke, T. P. Anderson, Dennis R. Alexander, George Gogos, Sidy Ndao

Department of Mechanical and Materials Engineering: Faculty Publications

A pool boiling phenomenon referred to as secondary boiling effects is discussed. Based on the experimental trends, a mechanism is proposed that identifies the parameters that lead to this phenomenon. Secondary boiling effects refer to a distinct decrease in the wall superheat temperature near the critical heat flux due to a significant increase in the heat transfer coefficient. Recent pool boiling heat transfer experiments using femtosecond laser processed Inconel, stainless steel, and copper multiscale surfaces consistently displayed secondary boiling effects, which were found to be a result of both temperature drop along the microstructures and nucleation characteristic length scales. The …

Experimental Explanation Of The Formation Mechanism Of Surface Mound-Structures By Femtosecond Laser On Polycrystalline Ni60Nb40, Edwin Peng, A. Tsubaki, Craig A. Zuhlke, Meiyu Wang, Ryan Bell, Michael J. Lucis, Troy P. Anderson, Dennis R. Alexander, George Gogos, Jeffrey E. Shield

Department of Mechanical and Materials Engineering: Faculty Publications

Femtosecond laser surface processing (FLSP) is an emerging technique for creating functionalized surfaces with specialized properties, such as broadband optical absorption or superhydrophobicity/ superhydrophilicity. It has been demonstrated in the past that FLSP can be used to form two distinct classes of mound-like, self-organized micro/nanostructures on the surfaces of various metals. Here, the formation mechanisms of below surface growth (BSG) and above surface growth (ASG) mounds on polycrystalline Ni₆₀Nb₄₀ are studied. Cross-sectional imaging of these mounds by focused ion beam milling and subsequent scanning electron microscopy revealed evidence of the unique formation processes for each class of …

Analytical Solution For Speed To Achieve A Desired Operating Point For A Given Fan Or Pump, Michael F. Kocher, Jeyamkondan Subbiah

Department of Agricultural and Biological Systems Engineering: Faculty Publications

The Affinity Laws for fans (and pumps) provide a way of determining new fan or pump speed given fan or pump performance curve data and a desired operating point (combination of flow rate and pressure) that does not fall on the curve. However, the affinity law calculations require using a point on the curve (hereafter referred to as the “basic point”) to determine the new speed. Most references regarding the Affinity Laws do not give a clear description of the method for determining the “basic point”, and improper selection of this point can affect the results considerably. This article describes …

In-Field Fuel Use And Load States Of Agricultural Field Machinery, Santosh Pitla, Joe D. Luck, Jared Werner, Nannan Lin, Scott A. Shearer

Department of Agricultural and Biological Systems Engineering: Faculty Publications

The ability to define in-field tractor load states offers the potential to better specify and characterize fuel consumption rate for various field operations. For the same field operation, the tractor experiences diverse load demands and corresponding fuel use rates as it maneuvers through straight passes, turns, suspended operation for adjustments, repair and maintenance, and biomass or other material transfer operations. It is challenging to determine the actual fuel rate and load states of agricultural machinery using force prediction models, and hence, some form of in-field data acquisition capability is required. Controller Area Networks (CAN) available on the current model tractors …

Arbitrary Lagrangian-Eulerian Method Investigation On Fuel Tank Strap Simulation Under Proving Ground Condition, Guangtian Song

Wayne State University Dissertations

The Arbitrary Lagrangian-Eulerian (ALE) is a hybrid finite element formulation that can alleviate many of the drawbacks from the traditional Lagrangian-based and Eulerian-based finite element simulations, which is developed through combining modern algorithms for Lagrangian hydrodynamics, meshing technology and remap methods developed for high-resolution Eulerian methods. Lagrangian-based finite element formulations is that the computational system moves with the material and main drawback is that it will face severe problems to deal with strong distortions in the computational domain. Eulerian-based finite element formulations is that the computational system is a prior fixed in space and unable to deal easily with fluids …

Development Of An Elderly Female Torso Finite Element Model For Restraint System Research And Development Applications, Anil Kalra Kalra

Wayne State University Dissertations

Elderly females are found to be one of the most vulnerable segments of population during motor vehicle crashes and their population is increasing in the coming decades. Current design of restraint systems as well as other passive safety measures are designed based on anthropomorphic details of younger population. Developing another dummy representing elderly female population is a costly effort, while a finite element (FE) model of elderly female with similar anthropomorphic details and age- and gender-specific material properties can be a better alternative solution. The current research focuses on the development of a FE model of an elderly female torso, …

Filter Performance Under Simulated Real-World Conditions, Qiang Wang

Theses and Dissertations

Evaluating the performance of filter media for filtration applications is essential to assure design engineers and users that filter device will deliver promised performance for specific applications under the environmental stress. The study of particle loading characteristics of filter media in the laboratory setting is typically performed under the steady flow conditions, i.e., at the constant particle concentration and flow rate. In reality, filtration products are operated under the situations that the flow rate and mass concentration of particles are varied in time. The success of translating the laboratory data to estimate the performance of filter media in the fields …

Fabricating Superhydrophobic And Superoleophobic Surfaces With Multiscale Roughness Using Airbrush And Electrospray, Karam N. Almilaji

Theses and Dissertations

Examples of superhydrophobic surfaces found in nature such as self-cleaning property of lotus leaf and walking on water ability of water strider have led to an extensive investigation in this area over the past few decades. When a water droplet rests on a textured surface, it may either form a liquid-solid-vapor composite interface by which the liquid droplet partially sits on air pockets or it may wet the surface in which the water replaces the trapped air depending on the surface roughness and the surface chemistry. Super water repellent surfaces have numerous applications in our daily life such as drag …

The Relationship Between High-Cycle Fatigue And Tensile Properties In Cast Aluminum Alloys, Huseyin Ozdes

UNF Graduate Theses and Dissertations

Cast aluminum alloys are common in automotive and aerospace applications due to their high strength-to-density ratio. Fracture data for cast aluminum alloys, such as fatigue life, tensile strength and elongation, are heavily affected by the structural defects, such as pores and bifilms. There have been numerous studies in which either fatigue performance or tensile deformation were characterized and linked to casting defects. However, a comprehensive study that correlates tensile and fatigue properties has not been reported. The present study is motivated to fill this gap. The main objective of the investigation is to analyze the link between tensile and fatigue …

Comparative Analysis Of Locally Available Materials For Treadle Pump Seals In Senegal, West Africa, Brennan Tymrak

Dissertations, Master's Theses and Master's Reports

For rural farmers in Senegal, West Africa, pulling water for irrigation can be a laborious but necessary task during the dry season to earn income from vegetable gardening. Traditional water pulling methods are inexpensive but require great physical effort, while modern machines decrease the labor burden but at a high financial cost. This study looked at an intermediate water pulling technology, the treadle pump, and how it could be improved to become more desirable for use in agricultural irrigation. A treadle pump was built and tested during field work in a rural Senegalese village. Observations from field testing prompted a …

Developing And Testing An Anguilliform Robot Swimming With Theoretically High Hydrodynamic Efficiency, John B. Potts Iii

LSU New Orleans Theses and Dissertations

An anguilliform swimming robot replicating an idealized motion is a complex marine vehicle necessitating both a theoretical and experimental analysis to completely understand its propulsion characteristics. The ideal anguilliform motion within is theorized to produce ``wakeless'' swimming (Vorus, 2011), a reactive swimming technique that produces thrust by accelerations of the added mass in the vicinity of the body. The net circulation for the unsteady motion is theorized to be eliminated.

The robot was designed to replicate the desired, theoretical motion by applying control theory methods. Independent joint control was used due to hardware limitations. The fluid velocity vectors in the …

Design Of A Tandem Rotor Hovering Vehicle, Brent Kostich

Honors Theses

An investigation of thrust vectoring and an examination of existing tandem rotor dynamics were used to develop a structural body for a tandem rotor vehicle, derive the equations of motion of the system, and simulate a dynamic model of the vehicle. A vehicle prototype was constructed while further application of remote control capabilities, flight testing, and control development were researched. The dynamic simulation was based on a linear model of the system so as to open the possibility of implementing a control system. The simulation results show that thrust synchronization yields a predictable motion response. The prototype constructed did not …

Machine Components Test, Brandon Younger, Lauren Romero, Carlos Padilla

Mechanical Engineering

To enhance California Polytechnic State University’s Mechanical Engineering program, Dr. Schuster has sponsored Brandon Younger, Lauren Romero, and Carlos Padilla to design and develop a new lab for students in the Intermediate Design class to test real mechanical components. This report discusses the background and ideation process that lead to the development of the Educational Mechanical Breadboard for Transmission System Components (Machine Components Test). Additionally, detailed drawings, 3D modeling, testing plans, and analysis are included to show how the Machine Components Test design will work and be validated.

Squirting Balloon Toy, Rachael Schelley, Elizabeth Wilhelm

Mechanical Engineering

The main goal of the Squirting Balloon Toy project was to create a new toy that combined both a helium balloon and a squirting water component near the base of the balloon. The toy will be sold at theme parks, fairs, and to other retailers such as toy stores with the target audience of primarily children and their parents, or any individuals seeking a good laugh when they spray their unsuspecting target. As a result, the toy was designed to be both visually appealing and to have an element of surprise. After testing and analyzing four different conceptual designs, two …

Underwater Rope Fatigue Testing Machine, Napoleon Nino, Andrew Pimentel

Mechanical Engineering

The design and fabrication of an underwater rope fatigue testing machine meant to simulate the effects of an oceanic environment and the effects on rope.

High Temperature Hepa Filter Test Unit Upgrades, Alexander Krippner, Ian Corcorran, Michael Burlando

Mechanical Engineering

No abstract provided.

Imaging Thermal Conductivity With Nanoscale Resolution Using A Scanning Spin Probe, Abdelghani Laraoui, Halley Aycock-Rizzo, Yang Gao, Xi Lu, Elisa Riedo, Carlos A. Meriles

Department of Mechanical and Materials Engineering: Faculty Publications

The ability to probe nanoscale heat flow in a material is often limited by lack of spatial resolution. Here, we use a diamond-nanocrystal-hosted nitrogen-vacancy centre attached to the apex of a silicon thermal tip as a local temperature sensor. We apply an electrical current to heat up the tip and rely on the nitrogen vacancy to monitor the thermal changes the tip experiences as it is brought into contact with surfaces of varying thermal conductivity. By combining atomic force and confocal microscopy, we image phantom microstructures with nanoscale resolution, and attain excellent agreement between the thermal conductivity and topographic maps. …

System And Method For Estimating States Of Spacecraft In Planet-Moon Environment, Piyush Grover

Department of Mechanical and Materials Engineering: Faculty Publications

A method estimates a state of a spacecraft in a planet-moon environment by executing iteratively a particle filter. The particle filter comprising integrates individually states of each particle of the particle filter according to a probability-evolution equation using a model of the state of the spacecraft represented as a planar circular restricted three-body problem and determines a prior probability of each particle as a previous posterior probability of a corresponding particle during a previous iteration. A joint probability distribution of the state of the spacecraft is determines using the states of each particle and the prior probabilities of each particle …

Characterization Of Hydrogel Curing Methods For Manufacturability, Hannah E. Brown, Rebecca K. Kramer, Edward L. White

The Summer Undergraduate Research Fellowship (SURF) Symposium

In the field of soft robotics, hydrogels possess material properties that allow them to function as both soft strain sensors and dielectric elastomer actuators. However, there is still much that needs to be understood about the curing process of hydrogels and the resulting material characteristics before manufacturing these devices can be accomplished. In this study, we investigated the effect of curing time and sample volume on the as-cured material properties of acrylamide-based hydrogels hydrated with lithium and magnesium chloride salt solutions. Samples were cured at room temperature, 60° C and 100° C, and the resulting changes in mechanical stiffness and …

Optimization In The Simulation Of Jammed Polyhedral Particles, Joseph W. Mynhier, Ishan Srivastava, Timothy S. Fisher

The Summer Undergraduate Research Fellowship (SURF) Symposium

Energy loss due to poor transport properties in electrically and thermally conducting materials, such as battery electrodes and thermoelectric composites, contributes to the energy inefficiency of electronic devices. For conductive materials composed of granular materials, particle-particle contact topology strongly governs the efficiency of energy transfer. Although there is a large body of existing work on the arrangements made by granular materials comprised of spherical particles, less is known about the mechanically stable arrangements of granular materials made of convex polyhedra. This project seeks to create a computer simulation of the solidification of convex polyhedra from a diffuse state into a …

Influences Of Wind On Automotive Interior Sound Quality, Sara Huelsman, Patricia Davies, Daniel Carr

The Summer Undergraduate Research Fellowship (SURF) Symposium

The effects of noise on human health (both mental and physical) are well known, and motivation to decrease noise in daily life is prevalent. Wind noise within automotive interior cabins could be detrimental to human health and comfort because of the negative impact on speech intelligibility and fatigue overall. There is little information on human perception of wind noise in automobile interiors though Loudness and Articulation Index have been examined as predictors of human response. They have been found to predict well in some circumstances, but not in others. In this research, a variety of sound quality metrics are being …

Towards An Optical In-Line Characterization Of Nano Petals, Yiming Ding, Huisung Kim, Euiwon Bae

The Summer Undergraduate Research Fellowship (SURF) Symposium

Carbon Nano Petals (i.e. CNPs) are cantilevered multilayer grapheme sheets that are seeded from core graphite fibers. The resulting structure offers a possibility of minimizing interfacial losses in transport application, improved interactions with surrounding matrix materials in composites, and a route toward substrate independence for device applications. The mass production of CNPs on the substrate required a method that can provide synchronous feedback on the sample status without pulling them out of the production line. Different optical properties can be observed when surfaces with different roughness are illuminated with a highly coherent light such as a laser beam. Similarly, CNPs …