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Full-Text Articles in Materials Science and Engineering

The Effect Of Compaction Temperature And Pressure On Mechanical Properties Of 3d Printed Short Glass Fiber Composites, Pushpashree Jain Ajith Kumar Jain Dec 2020

The Effect Of Compaction Temperature And Pressure On Mechanical Properties Of 3d Printed Short Glass Fiber Composites, Pushpashree Jain Ajith Kumar Jain

Mechanical & Aerospace Engineering Theses & Dissertations

Among many thermoplastics that are used in engineering, polyamide 6 (nylon 6) is an extremely versatile engineering thermoplastic. Nylon filled with glass fibers has higher mechanical strength and high wear resistance than general purpose nylon. 3D printed composites, based on fused filament modeling, typically suffer from poor bead-to-bead bonding and relatively high void content, limiting their mechanical properties

This thesis explores the effect of compaction pressure and temperature on improving the mechanical properties of 3D printed composites. Engineering moduli in the printing and transverse to printing direction, as well as ultimate strength were measured using the tensile testing with Digital …


Numerical Analysis Of A Roadway Piezoelectric Harvesting System, Abdul Rahman Badawi Dec 2020

Numerical Analysis Of A Roadway Piezoelectric Harvesting System, Abdul Rahman Badawi

Mechanical & Aerospace Engineering Theses & Dissertations

Highways, streets, bridges, and sidewalks with heavy traffic dissipate a considerable amount of waste mechanical energy every day. Piezoelectric energy harvesting devices are a very promising technology that can convert the waste mechanical energy to clean and renewable energy to enhance the sustainability of infrastructures. Research efforts in large-scale energy harvesting have led to the advancement of piezoelectric devices to the point that large-scale implementation is starting to become more feasible. The energy harvested by these devices can be used in many ways such as providing heating or cooling, melting ice, monitoring structural conditions in bridges and tunnels, and powering …


Toward Understanding Underlying Mechanisms Of Drag Reduction In Turbulent Flow Control, Alex Rogge Dec 2020

Toward Understanding Underlying Mechanisms Of Drag Reduction In Turbulent Flow Control, Alex Rogge

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

The underlying mechanisms of three different flow-control strategies on drag reduction in a turbulent channel flow are investigated by direct numerical simulations. These strategies include the addition of a small concentration of long-chain polymers into a fluid, the incorporation of slip surfaces, and the application of an external body force. While it has been believed that such methods lead to a skin-friction reduction by controlling near-wall flow structures, the underlying mechanisms at play are still not as clear. In this study, a temporal analysis is employed to elucidate underlying drag-reduction mechanisms among these methods. The analysis is based on the …


High-Temperature Optoelectronic Device Characterization And Integration Towards Optical Isolation For High-Density Power Modules, Syam Madhusoodhanan Dec 2020

High-Temperature Optoelectronic Device Characterization And Integration Towards Optical Isolation For High-Density Power Modules, Syam Madhusoodhanan

Graduate Theses and Dissertations

Power modules based on wide bandgap (WBG) materials enhance reliability and considerably reduce cooling requirements that lead to a significant reduction in total system cost and weight. Although these innovative properties lead power modules to higher power density, some concerns still need to be addressed to take full advantage of WBG-based modules. For example, the use of bulky transformers as a galvanic isolation system to float the high voltage gate driver limits further size reduction of the high-temperature power modules. Bulky transformers can be replaced by integrating high-temperature optocouplers to scale down power modules further and achieve disrupting performance in …


The Effect Of Guide Vane Opening Variations And Total Blades On Cross Flow Turbine Performance Using Computational Fluid Dynamic, Muhamad Akbar Navis, Heru Suryanto, Putut Murdanto Nov 2020

The Effect Of Guide Vane Opening Variations And Total Blades On Cross Flow Turbine Performance Using Computational Fluid Dynamic, Muhamad Akbar Navis, Heru Suryanto, Putut Murdanto

Journal of Mechanical Engineering Science and Technology (JMEST)

Indonesia is an agrarian country that continuously produces water, so it has the potential to develop a hydroelectric power plant. Computational Fluid Dynamic (CFD) application could be used to be an economical, quick, and efficient approach to improve the engineering design and turbine performance. This research aimed to find the effect of guide vane opening variations and total blades on cross-flow turbine performance using CFD simulation. This research used experimental modelling method with ANSYS program for turbine design with 22, 24, and 26 turbine blades and guide vane opening variations of 12°, 16°, 20°, 24°, and 36°. The data were …


Energy And Exergy Efficiency Of Double Slope Passive Solar Still, Jandri Fan Ht Saragi, Wawan Septiawan Damanik Nov 2020

Energy And Exergy Efficiency Of Double Slope Passive Solar Still, Jandri Fan Ht Saragi, Wawan Septiawan Damanik

Journal of Mechanical Engineering Science and Technology (JMEST)

Solar desalination functions to filter water, both sea water and brackish water, to produce clean water that is fit for consumption with energy from the sun. Solar energy is a renewable energy source that has been widely studied for its use. One of its uses is in a double slope passive solar still where the sun is the main source. Energy and exergy obtained from solar energy are not all used to evaporate water in the desalination system, so it is necessary to calculate efficiency energy and exergy in the system. This study aims to obtain data on the amount …


Characteristics Biolubricant Enriched With Nanoparticle Additives: A Review, Zhahra Hanif Sholiha, Gaguk Jatisukamto Nov 2020

Characteristics Biolubricant Enriched With Nanoparticle Additives: A Review, Zhahra Hanif Sholiha, Gaguk Jatisukamto

Journal of Mechanical Engineering Science and Technology (JMEST)

The engine movement mechanism is a system composed of machine elements that contact or rub against each other between these surfaces. Surfaces that rub against each other will cause a friction force that causes wear on the surface, so it requires energy to fight the friction force. Lubricants are needed to reduce friction and reduce wear rates, where lubricants are generally made of mineral materials. Lubricants made from synthetic materials are non-renewable and cause environmental problems. The development of biolubricants as lubricating materials based on animal fats or vegetable oils is continuously being carried out. This study aims to observe …


Optimization Of Stir Casting Of Aluminum Matrix Composites (Amcs) With Filler Of Recycled Glass Powder (Rgp) For The Mechanical Properties, Yusup Hendronursito, Tumpal Ojahan, Anang Anshori, Asep Yunanto Nov 2020

Optimization Of Stir Casting Of Aluminum Matrix Composites (Amcs) With Filler Of Recycled Glass Powder (Rgp) For The Mechanical Properties, Yusup Hendronursito, Tumpal Ojahan, Anang Anshori, Asep Yunanto

Journal of Mechanical Engineering Science and Technology (JMEST)

A study of making Aluminum Matrix Composites (AMCs) uses recycled glass powder (RGP) as a filler has been carried out through the stir casting process. The experimental design uses the Taguchi method of 3^3 orthogonal array L9 with the parameters of powder size (20>x> 80, 80>y> 200, 200>z> 325), percentage of filler vs matrix (2%, 7%, 12%), and stirring time (30 Seconds, 3 Minutes, 12 Minutes). The optimum conditions for the hardness of Al-GRp composites were obtained from specimens with Mesh powder size parameters 200> z> 325, the percentage of glass vs aluminum powder was 12% wt, …


Surface Properties And Adsorption Capacities Of Rice Bran-Activated Carbon, Dewa Ngakan Ketut Putra Negara, Tjokorda Gde Tirta Nindhia, Wayan Nata Septiadi Nov 2020

Surface Properties And Adsorption Capacities Of Rice Bran-Activated Carbon, Dewa Ngakan Ketut Putra Negara, Tjokorda Gde Tirta Nindhia, Wayan Nata Septiadi

Journal of Mechanical Engineering Science and Technology (JMEST)

The growing need for activated carbon requires alternative raw materials to replace non-renewable raw materials whose existence is decreasing. Biomass is a very promising precursor, one of which is from rice bran. This research concerns the development of activated carbon derived from rice bran. Carbonization was carried out at 600 OC and physically activated with nitrogen flow rates of 150 mL/min for 40, 80, and 120 minutes. The activated carbons produced (AC-D40, AC-D80, and AC-D120) were characterized to determine the surface properties, surface morphology, and adsorption capacity for nitrogen and blue methylene adsorptions. The results showed that activated carbon that …


Design Of Savonius Vertical Axis Wind Turbine For Vehicle, Filian Arbiyani, Fernando Pranata Lasut Nov 2020

Design Of Savonius Vertical Axis Wind Turbine For Vehicle, Filian Arbiyani, Fernando Pranata Lasut

Journal of Mechanical Engineering Science and Technology (JMEST)

The use of cellular phones is increasing in society, but due to the limited battery capacity of cell phones, it is necessary to charge the battery when travelling in the long distances. The Savonius type wind turbine has a potential as an energy source harvesting the wind energy flowing around the car. However, due to the available space on the car, careful design of Savonius vertical axis wind turbine for vehicle is necessary. The research is conducted numerically using MATLAB software. The wind speed, Reynolds number, and electric power output are numerically simulated to obtain the swept area design. Innovative …


New Design Of Aluminum 6061 Welding Joining Using Friction Stir Welding Method, Widia Setiawan, Nugroho Santoso, Surojo Surojo Nov 2020

New Design Of Aluminum 6061 Welding Joining Using Friction Stir Welding Method, Widia Setiawan, Nugroho Santoso, Surojo Surojo

Journal of Mechanical Engineering Science and Technology (JMEST)

Parallel, lap, corner, and T joints are commonly used in fusion welding and solid welding. Other joints made are lap and butt joint. This study aims to evaluate a new design of fitting model single U and double U for friction stirr welding of Aluminum. Aluminum sheet 6061with a thickness of 10 mm, will be cut to a length of 150 mm and a width of 100 mm, then a locking groove will be made with an inner size of 5 mm and a length of 150 mm The flow is used to be paired in the FSW process. This …


Tool Life Prediction Of Ti [C,N] Mixed Alumina Ceramic Cutting Tool Using Gradient Descent Algorithm On Machining Martensitic Stainless Steel, Joseph Daniel S, Senthil Kumar A Nov 2020

Tool Life Prediction Of Ti [C,N] Mixed Alumina Ceramic Cutting Tool Using Gradient Descent Algorithm On Machining Martensitic Stainless Steel, Joseph Daniel S, Senthil Kumar A

Journal of Mechanical Engineering Science and Technology (JMEST)

In automated manufacturing systems, most of the manufacturing processes, including machining, are automated. Automatic tool change is one of the important parameters for reducing manufacturing lead time. Machining studies on Martensitic Stainless Steel was conducted using Ti[C,N] mixed alumina ceramic cutting tool. Tool life was evaluated using flank wear criterion. The tool life obtained from experimental machining process was taken as training dataset and test dataset for machine learning. Tool life model was developed using Gradient Descent Algorithm. The accuracy of the machine learning model was tested using the test data, and 99.83% accuracy was obtained.


Moisture Reduction Of Honey In Dehumidification And Evaporation Processes, Anang Lastriyanto, Sasongko Aji Wibowo, Erwan Erwan, Firman Jaya, Jati Batoro, Dewi Masyithoh, J.S.A Lamerkabel Nov 2020

Moisture Reduction Of Honey In Dehumidification And Evaporation Processes, Anang Lastriyanto, Sasongko Aji Wibowo, Erwan Erwan, Firman Jaya, Jati Batoro, Dewi Masyithoh, J.S.A Lamerkabel

Journal of Mechanical Engineering Science and Technology (JMEST)

The high water content of honey can lead to fermentation and accelerate the deterioration of honey. One way to prevent fermentation in honey is to reduce the water content of honey. There are several ways to reduce the water content of honey, namely through a dehumidifier and evaporation. This study aimed to examine the relationship of reduced water content towards time in between dehumidifier and evaporation processes. The research method uses an exponential equation model to determine the value of the constant (K). The constant value (K) is used to predict the rate of reduction in moisture content between the …


Review Of Γ’ Rafting Behavior In Nickel-Based Superalloys: Crystal Plasticity And Phase-Field Simulation, Zhiyuan Yu, Xinmei Wang, Fuqian Yang, Zhufeng Yue, James C. M. Li Nov 2020

Review Of Γ’ Rafting Behavior In Nickel-Based Superalloys: Crystal Plasticity And Phase-Field Simulation, Zhiyuan Yu, Xinmei Wang, Fuqian Yang, Zhufeng Yue, James C. M. Li

Chemical and Materials Engineering Faculty Publications

Rafting is an important phenomenon of the microstructure evolution in nickel-based single crystal superalloys at elevated temperature. Understanding the rafting mechanism and its effect on the microstructure evolution is of great importance in determining the structural stability and applications of the single crystal superalloys. Phase-field method, which is an excellent tool to analyze the microstructure evolution at mesoscale, has been gradually used to investigate the rafting behavior. In this work, we review the crystal plasticity theory and phase-field method and discuss the application of the crystal plasticity theory and phase-field method in the analysis of the creep deformation and microstructure …


The Economics Of Classroom 3-D Printing Of Open-Source Digital Designs Of Learning Aids, Nicole Gallup, Joshua M. Pearce Nov 2020

The Economics Of Classroom 3-D Printing Of Open-Source Digital Designs Of Learning Aids, Nicole Gallup, Joshua M. Pearce

Michigan Tech Publications, Part 1

While schools struggle financially, capital for purchasing physical learning aids is often cut. To determine if costs could be reduced for learning aids, this study analyzed classroom-based distributed digital manufacturing using 3-D printing of open-source learning aid designs. Learning aid designs are analyzed in detail for their economic viability considering printing and assembly costs with purchased components and compared to equivalent or inferior commercial products available on Amazon. The results show current open-source 3-D printers are capable of manufacturing useful learning aids and that doing so provides high economic savings in the classroom. Overall, the average learning aid would save …


Water Conservation Potential Of Self-Funded Foam-Based Flexible Surface-Mounted Floatovoltaics, Kaomi Soulemane Hayibo, Pierce Mayville, Ravneet Kaur Kailey Nov 2020

Water Conservation Potential Of Self-Funded Foam-Based Flexible Surface-Mounted Floatovoltaics, Kaomi Soulemane Hayibo, Pierce Mayville, Ravneet Kaur Kailey

Michigan Tech Publications, Part 1

A potential solution to the coupled water–energy–food challenges in land use is the concept of floating photovoltaics or floatovoltaics (FPV). In this study, a new approach to FPV is investigated using a flexible crystalline silicon-based photovoltaic (PV) module backed with foam, which is less expensive than conventional pontoon-based FPV. This novel form of FPV is tested experimentally for operating temperature and performance and is analyzed for water-savings using an evaporation calculation adapted from the Penman–Monteith model. The results show that the foam-backed FPV had a lower operating temperature than conventional pontoon-based FPV, and thus a 3.5% higher energy output per …


A First Investigation Of Agriculture Sector Perspectives On The Opportunities And Barriers For Agrivoltaics, Alexis Pascaris, Chelsea Schelly, Joshua M. Pearce Nov 2020

A First Investigation Of Agriculture Sector Perspectives On The Opportunities And Barriers For Agrivoltaics, Alexis Pascaris, Chelsea Schelly, Joshua M. Pearce

Michigan Tech Publications, Part 1

Agrivoltaic systems are a strategic and innovative approach to combine solar photovoltaic (PV)-based renewable energy generation with agricultural production. Recognizing the fundamental importance of farmer adoption in the successful diffusion of the agrivoltaic innovation, this study investigates agriculture sector experts’ perceptions on the opportunities and barriers to dual land-use systems. Using in-depth, semistructured interviews, this study conducts a first study to identify challenges to farmer adoption of agrivoltaics and address them by responding to societal concerns. Results indicate that participants see potential benefits for themselves in combined solar and agriculture technology. The identified barriers to adoption of agrivoltaics, however, include: …


Aerosol Jet Printed Capacitive Strain Gauge For Soft Structural Materials, Kiyo T. Fujimoto, Jennifer K. Watkins, Timothy Phero, Takoda Bingham, Kshama Lakshmi Ranganatha, Benjamin C. Johnson, Zhangxian Deng, Brian Jaques, David Estrada Nov 2020

Aerosol Jet Printed Capacitive Strain Gauge For Soft Structural Materials, Kiyo T. Fujimoto, Jennifer K. Watkins, Timothy Phero, Takoda Bingham, Kshama Lakshmi Ranganatha, Benjamin C. Johnson, Zhangxian Deng, Brian Jaques, David Estrada

Materials Science and Engineering Faculty Publications and Presentations

Soft structural textiles, or softgoods, are used within the space industry for inflatable habitats, parachutes and decelerator systems. Evaluating the safety and structural integrity of these systems occurs through structural health monitoring systems (SHM), which integrate non-invasive/non-destructive testing methods to detect, diagnose, and locate damage. Strain/load monitoring of these systems is limited while utilizing traditional strain gauges as these gauges are typically stiff, operate at low temperatures, and fail when subjected to high strain that is a result of high loading classifying them as unsuitable for SHM of soft structural textiles. For this work, a capacitance based strain gauge (CSG) …


Study On Cation Exchange Of A Lead Coordination Polymer Targeting Dynamic Mixed Cation Doped And Mixed-Valent Coordination Polymers, Hamisu Aliyu Mohammed Nov 2020

Study On Cation Exchange Of A Lead Coordination Polymer Targeting Dynamic Mixed Cation Doped And Mixed-Valent Coordination Polymers, Hamisu Aliyu Mohammed

Student Works (2020-2029)

Solid solution in Metal-Organic Coordination Polymers (MOCPs) is an emerging synthetic pathway for modifying chemical compositions and has been expansively investigated. It has been demonstrated to be an important tool for engineering novel functional materials that otherwise have not been synthesized via the conventional technique. Although stable solid material with variable functionalities and intriguing structural motifs could be engineered by judicious selection of multivariate metal centers and multifunctional ligands. However, solid solution featuring mixed valence in MOCP is rare. Motivated by the ability of Pb2+ to adopt range of coordination numbers (CN) and chemical environments (CE), in addition to its …


Examination Of Early Stage Grey Iron Solidification Through The Development Of Fast-Quench Methodology, James C. Liggett Nov 2020

Examination Of Early Stage Grey Iron Solidification Through The Development Of Fast-Quench Methodology, James C. Liggett

Honors College Theses

As grey iron casting accounts for a significant share of the foundry industry, proper understanding of the effects of solidification and growth mechanisms on the mechanical properties of grey iron is crucial. Prior experimentation has been performed examining early stage solidification and growth of the carbon phase of ductile iron, in which rapid quench samples are obtained which detail austenite-graphite interactions during solidification. This prior experimentation is built upon in though this research and applied to examine the early stage growth of flake graphite in grey iron. The purpose of this research is to validate a proposed fast-quench method by …


Radiation Modified Chitosan/Polyvinyl Alcohol Film With Polyvinyl Pyrrolidone Coating For Heavy Metal Ion Removal, Norhashidah Talip Nov 2020

Radiation Modified Chitosan/Polyvinyl Alcohol Film With Polyvinyl Pyrrolidone Coating For Heavy Metal Ion Removal, Norhashidah Talip

Student Works (2020-2029)

Chitosan (CS) / Polyvinyl Alcohol (PVA) films were obtained by solution casting method. To be used in the water treatment application, these film need to be improved in mechanical strength. In this study, 2% (w/v) chitosan and 5% (w/v) PVA were blend at different CS: PVA weight ratios (50:50, 70:30 and 90:10). These mixtures were then transformed into films by solution casting method. Mechanical properties of the films were evaluated using tensile strength test where, at 70:30 of CS: PVA ratio gave the best tensile strength. Therefore, this composition was selected to proceed with the radiation modification with Polyvinyl Pyrrolidone …


Machine Learning Augmentation Micro-Sensors For Smart Device Applications, Mohammad H. Hasan Nov 2020

Machine Learning Augmentation Micro-Sensors For Smart Device Applications, Mohammad H. Hasan

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

Novel smart technologies such as wearable devices and unconventional robotics have been enabled by advancements in semiconductor technologies, which have miniaturized the sizes of transistors and sensors. These technologies promise great improvements to public health. However, current computational paradigms are ill-suited for use in novel smart technologies as they fail to meet their strict power and size requirements. In this dissertation, we present two bio-inspired colocalized sensing-and-computing schemes performed at the sensor level: continuous-time recurrent neural networks (CTRNNs) and reservoir computers (RCs). These schemes arise from the nonlinear dynamics of micro-electro-mechanical systems (MEMS), which facilitates computing, and the inherent ability …


Laser Powder Bed Fusion Of Nitihf High-Temperature Shape Memory Alloy: Effect Of Process Parameters On The Thermomechanical Behavior, Mohammadreza Nematollahi, Guher P. Toker, Keyvan Safaei, Alejandro Hinojos, S. Ehsan Saghaian, Othmane Benafan, Michael J. Mills, Haluk E. Karaca, Mohammad Elahinia Nov 2020

Laser Powder Bed Fusion Of Nitihf High-Temperature Shape Memory Alloy: Effect Of Process Parameters On The Thermomechanical Behavior, Mohammadreza Nematollahi, Guher P. Toker, Keyvan Safaei, Alejandro Hinojos, S. Ehsan Saghaian, Othmane Benafan, Michael J. Mills, Haluk E. Karaca, Mohammad Elahinia

Mechanical Engineering Faculty Publications

Laser powder bed fusion has been widely investigated for shape memory alloys, primarily NiTi alloys, with the goal of tailoring microstructures and producing complex geometries. However, processing high temperature shape memory alloys (HTSMAs) remains unknown. In our previous study, we showed that it is possible to manufacture NiTiHf HTSMA, as one of the most viable alloys in the aerospace industry, using SLM and investigated the effect of parameters on defect formation. The current study elucidates the effect of process parameters (PPs) on the functionality of this alloy. Shape memory properties and the microstructure of additively manufactured Ni-rich NiTiHf alloys were …


Atom Trapping And Its Role On The Nucleation & Growth Of Platinum Nanoparticles, Deepak Kunwar Nov 2020

Atom Trapping And Its Role On The Nucleation & Growth Of Platinum Nanoparticles, Deepak Kunwar

Chemistry and Chemical Biology ETDs

Diesel oxidation catalysts deactivate due to Pt sintering, a major problem in automotive industries. To make sure they operate effectively throughout the lifetime of the vehicle, automotive industries are putting an excessive amount of Pt. There is a need to develop a catalyst that serves long term performance with minimal use of Pt. Jones et al.1 demonstrated that ceria traps Pt atoms. His work generated some logical and valid questions such as what is the mechanism for the formation of anomalously large Pt particles? What is the upper limit of Pt metal loading in the form of single atoms …


A Bibliometric Survey On Polymer Composites In Energy Storage Applications, Babaji Ghule, Meena Laad Nov 2020

A Bibliometric Survey On Polymer Composites In Energy Storage Applications, Babaji Ghule, Meena Laad

Library Philosophy and Practice (e-journal)

Ceramic polymer composites have gained a significant place in energy storage applications for electrical capacitors due to their distinguished properties. There is a huge demand of capacitors with high energy density, high dielectric strength, negligibly low dielectric loss, light weight, chemically less reactive in energy storage applications. These requirements can be fulfilled by ceramic polymer composites only which exhibit all the above-mentioned characteristics. Considering the huge demand of such capacitors, it has attracted the attention of researchers around the world. The present work attempts to summarise all the research conducted on Polymer Composites for energy storage applications and provides an …


Desorption From Hot Scandate Cathodes: Effects On Vacuum Device Interior Surfaces After Long-Term Operation, Mujan N. Seif, Thomas John Balk, Matthew J. Beck Nov 2020

Desorption From Hot Scandate Cathodes: Effects On Vacuum Device Interior Surfaces After Long-Term Operation, Mujan N. Seif, Thomas John Balk, Matthew J. Beck

Chemical and Materials Engineering Faculty Publications

Scandate cathodes have exhibited superior emission properties compared to current state-of-the-art “M-type” thermionic cathodes. However, their integration into vacuum devices is limited in part by a lack of knowledge regarding their functional lifespan and behavior during operation. Here, we consider thermal desorption from scandate cathodes by examining the distribution of material deposited on interior surfaces of a sealed vacuum device after ~26,000 h of cathode operation. XPS, EDS, and TEM analyses indicate that on the order of 1 wt.% of the initial impregnate is desorbed during a cathode’s lifetime, Ca does not desorb uniformly with time, and little to no …


Effects Of Laser Power And Substrate On The Raman Shift Of Carbon-Nanotube Papers, Fuqian Yang, Shanshan Wang, Yuling Zhang Nov 2020

Effects Of Laser Power And Substrate On The Raman Shift Of Carbon-Nanotube Papers, Fuqian Yang, Shanshan Wang, Yuling Zhang

Chemical and Materials Engineering Faculty Publications

The progress in the fabrication of carbon-nanotube-based structures has made it possible to use Raman spectroscopy to measure the deformation states of carbon nanotubes and abutting materials. In this work, we investigate the effects of laser power and surrounding materials on the Raman shift of carbon-nanotube (CNT) papers for the laser intensity in a range of 0.071 to 1.415 kW/mm2 without action of mechanical loading. Two different configurations of the CNT papers are used in the Raman measurement; one uses a suspended CNT paper, and the other places a CNT paper on a glass or aluminum substrate. The experimental …


Proximity-Induced Magnetization In Graphene: Towards Efficient Spin Gating, Mihovil Bosnar, Ivor Lončarić, P. Lazić, Kirill Belashchenko, Igor Žutić Nov 2020

Proximity-Induced Magnetization In Graphene: Towards Efficient Spin Gating, Mihovil Bosnar, Ivor Lončarić, P. Lazić, Kirill Belashchenko, Igor Žutić

Kirill Belashchenko Publications

Gate-tunable spin-dependent properties could be induced in graphene at room temperature through the magnetic proximity effect by placing it in contact with a metallic ferromagnet. Because strong chemical bonding with the metallic substrate makes gating ineffective, an intervening passivation layer is needed. Previously considered passivation layers result in a large shift of the Dirac point away from the Fermi level, so that unrealistically large gate fields are required to tune the spin polarization in graphene (Gr). We show that a monolayer of Au or Pt used as the passivation layer between Co and graphene brings the Dirac point closer to …


New Metal Based Saturable Absorber For Ultrashort Pulse Generation, Muhammad Taufiq Ahmad Nov 2020

New Metal Based Saturable Absorber For Ultrashort Pulse Generation, Muhammad Taufiq Ahmad

Student Works (2020-2029)

Cost-efficient, robust and flexible laser systems are vital for a wide-range of applications ranging from high-precision material processing to biomedicine. This thesis aims to explore pure silver and gold based saturable absorbers (SAs) as Q-switcher and mode-locker in various fibre laser cavities. The generations of Q-switched pulses in 1-,1.55-, and 2-micron regions have been successfully demonstrated using a pure gold, which was deposited using electron beam deposition onto a PVA thin-film as SA. For instance, a stable Q-switched thulium-doped fibre laser (TDFL) operating at 1949 nm was successfully demonstrated with the gold SA. The proposed laser generates Q switched pulses …


Conversion From Metal Oxide To Mof Thin Films As A Platform Of Chemical Sensing, Meng Chen Nov 2020

Conversion From Metal Oxide To Mof Thin Films As A Platform Of Chemical Sensing, Meng Chen

USF Tampa Graduate Theses and Dissertations

Chemical sensor is working as a widely used device which can be applied to the detection of specific chemicals that are existing in the environment especially in gas phase. The detection of combustible and toxic chemicals can be extremely important in the field of both industrial and civil activities. The chemical sensor is commonly operating by utilizing a chemical or physical interaction between the specific chemical compound and the sensing functional unit, to obtain an electronic signal caused by the property change and realize the chemical detection. Traditional chemical gas sensors such as catalytic gas sensor, thermal conductivity gas sensor, …