Other Mechanical Engineering Commons^™

Monolithic Integration Of Hybrid Perovskite Single Crystals With Silicon For Highly Sensitive X - Ray Detectors, Jinsong Huang, Wei Wei

Department of Mechanical and Materials Engineering: Faculty Publications

Perovskite single crystal X - ray radiation detector devices including an X - ray wavelength - responsive active layer including an organolead trihalide perovskite single crystal, a substrate layer comprising an oxide, and a binding layer disposed between the active layer and the substrate layer. The binding layer including a binding molecule having a first functional group that bonds to the organolead trihalide perovskite single crystal and a second functional bonds with the oxide. Inclusion of the binding layer advantageously reduces device noise while retaining signal intensity.

Passivation Of Defects In Perovskite Materials For Improved Solar Cell Efficiency And Stability, Jinsong Huang, Xiaopeng Zheng

Department of Mechanical and Materials Engineering: Faculty Publications

Semiconductor devices , and methods of forming the same , include a cathode layer , an anode layer , and an active layer disposed between the cathode layer and the anode layer , wherein the active layer includes a perovskite layer . A passivation layer is disposed directly on a surface of the active layer between the cathode layer and the active layer , the passivation layer including a layer of material that passivates both cationic and anionic defects in the surface of the active layer .

Challenges And Signal Processing Of High Strain Rate Mechanical Testing, Barae Lamdini

Theses and Dissertations

Dynamic testing provides valuable insight into the behavior of materials undergoing fast deformation. During Split-Hopkinson Pressure Bar testing, stress waves are measured using strain gauges as voltage variations that are usually very small. Therefore, an amplifier is required to amplify the data and analyze it. One of the few available amplifiers designed for this purpose is provided by Vishay Micro-Measurements which limits the user’s options when it comes to research or industry. Among the challenges of implementing the Hopkinson technology in the industry are the size and cost of the amplifier. In this work, we propose a novel design of …

Ultra-Broadband And Polarization-Insensitive Metasurface Absorber With Behavior Prediction Using Machine Learning, Shobhit K. Patel, Juveriya Parmar, Vijay Katkar, Fahad Ahmed Al-Zahrani, Kawsar Ahmed

Department of Mechanical and Materials Engineering: Faculty Publications

The solar spectrum energy absorption is very important for designing any solar absorber. The need for absorbing visible, infrared, and ultraviolet regions is increasing as most of the absorbers absorb visible regions. We propose a metasurface solar absorber based on Ge₂Sb₂Te₅ (GST) substrate which increases the absorption in visible, infrared and ultraviolet regions. GST is a phase-changing material having two different phases amorphous (aGST) and crystalline (cGST). The absorber is also analyzed using machine learning algorithm to predict the absorption values for different wavelengths. The solar absorber is showing an ultra-broadband response covering a 0.2–1.5 …

Closed-Loop Control Of Meltpool Temperature In Directed Energy Deposition, Ziyad M. Smoqi, Ben Bevans, Aniruddha Gaikwad, James Craig, Alan Abul-Haj, Brent Roeder, Bill Macy, Jeffrey E. Shield, Prahalada K. Rao

Department of Mechanical and Materials Engineering: Faculty Publications

The objective of this work is to mitigate flaw formation in powder and laser-based directed energy deposition (DED) additive manufacturing process through close-loop control of the meltpool temperature. In this work, the meltpool temperature was controlled by modulating the laser power based on feedback signals from a coaxial two-wavelength imaging pyrometer. The utility of closed-loop control in DED is demonstrated in the context of practically inspired trapezoid-shaped stainlesssteel parts (SS 316L). We demonstrate that parts built under closed-loop control have reduced variation in porosity and uniform microstructure compared to parts built under open-loop conditions. For example, post-process characterization showed that …

Recent Advances In Biosensors For Detection Of Covid-19 And Other Viruses, Shobhit K. Patel, Jaymit Surve, Juveriya Parmar, Kawsar Ahmed, Francis M. Bui, Fahad Ahmed Al-Zahrani

Department of Mechanical and Materials Engineering: Faculty Publications

This century has introduced very deadly, dangerous, and infectious diseases to humankind such as the influenza virus, Ebola virus, Zika virus, and the most infectious SARS-CoV-2 commonly known as COVID-19 and have caused epidemics and pandemics across the globe. For some of these diseases, proper medications, and vaccinations are missing and the early detection of these viruses will be critical to saving the patients. And even the vaccines are available for COVID-19, the new variants of COVID-19 such as Delta, and Omicron are spreading at large. The available virus detection techniques take a long time, are costly, and complex and …

Permeability, Structural Changes, Flow Regime Transitions In Fuel Cell Catalyst Layers And A Model For Predicting Trapped Saturation For Two-Phase Flow In Porous Media, Karrar Takleef Alofari

Dissertations, Master's Theses and Master's Reports

Proper water management in Proton Exchange Membrane (PEM) fuel cell is important to achieve high performance. Understanding the percolation of the produced water at the cathode catalyst layer (CL) is critical for any robust water management technique. In this study, an ex-situ experimental setup is used to study percolation in the CL at different injection rates and relative humidity (RH) conditions. The results show that increasing the flow rate force the liquid to flow through the bulk of the pores due to the dominant viscous effect. On the other hand, at low injection rates, the capillary becomes dominant and liquid …

Recycled Printer Filament, Charlotte Hyland, Troy D. Molinar

Williams Honors College, Honors Research Projects

The purpose of this research is to examine the effects of recycling PLA filament for 3D printing on its material properties. After examining these effects, PLA and carbon fiber additives were mixed with recycled PLA pellets in different ratios to attempt to regain material properties lost in the recycling process. To complete these findings, an experiment was design and executed.

The research found that tensile strength during multiple iterations of recycling remained mostly unaffected, however, the strain degraded exponentially. In the PLA additive study, high ratios of PLA additive were able to increase the strength and strain properties of the …

Visualization And Validation Of Twin Nucleation And Early-Stage Growth In Magnesium, Lin Jiang, Mingyu Gong, Jian Wang, Zhiliang Pan, Xin Wang, Dalong Zhang, Y. Morris Wang, Jim Ciston, Andrew M. Minor, Mingjie Xu, Xiaoqing Pan, Timothy J. Rupert, Subhash Mahajan, Enrique J. Lavernia, Irene J. Beyerlein, Julie M. Schoenung

Department of Mechanical and Materials Engineering: Faculty Publications

The abrupt occurrence of twinning when Mg is deformed leads to a highly anisotropic response, making it too unreliable for structural use and too unpredictable for observation. Here, we describe an in-situ transmission electron microscopy experiment on Mg crystals with strategically designed geometries for visualization of a long-proposed but unverified twinning mechanism. Combining with atomistic simulations and topological analysis, we conclude that twin nucleation occurs through a pure-shuffle mechanism that requires prismatic-basal transformations. Also, we verified a crystal geometry dependent twin growth mechanism, that is the early-stage growth associated with instability of plasticity flow, which can be dominated either by …

Type Iii And Iv Deformation Twins In Minerals And Metals, John P. Hirth, Greg Hirth, Jian Wang

Department of Mechanical and Materials Engineering: Faculty Publications

Type IV twins are defined and shown to exist in triclinic crystal systems, as well as in some monoclinic and trigonal systems. Here, we focus on Pericline twins in triclinic plagioclase as an example. Type IV twins are associated with the irrationality of one of the twinning elements that is rational for a type II twin. The formation of type IV twins is accomplished through the shear on a K2 plane produced by the motion of twinning disconnections on a K1 plane, followed by rotational partitioning. The same systems where type IV twins are present also have type III twins …

Emissivity Prediction Of Functionalized Surfaces Using Artificial Intelligence, Greg Acosta, Andrew Reicks, Miguel Moreno, Alireza Borjali, Craig Zuhlke, Mohammad Ghashami

Department of Mechanical and Materials Engineering: Faculty Publications

Tuning surface emissivity has been of great interest in thermal radiation applications, such as thermophotovoltaics and passive radiative cooling. As a low-cost and scalable technique for manufacturing surfaces with desired emissivities, femtosecond laser surface processing (FLSP) has recently drawn enormous attention. Despite the versatility offered by FLSP, there is a knowledge gap in accurately predicting the outcome emissivity prior to fabrication. In this work, we demonstrate the immense advantage of employing artificial intelligence (AI) techniques to predict the emissivity of complex surfaces. For this aim, we used FLSP to fabricate 116 different aluminum samples. A comprehensive dataset was established by …

Construction Of A Peridynamic Model For Viscous Flow, Jiangming Zhao, Adam Larios, Florin Bobaru Ph.D.

Department of Mechanical and Materials Engineering: Faculty Publications

We derive the Eulerian formulation for a peridynamic (PD) model of Newtonian viscous flow starting from fundamental principles: conservation of mass and momentum. This formulation is different from models for viscous flow that utilize the so-called “peridynamic differential operator” with the classical Navier- Stokes equations. We show that the classical continuity equation is a limiting case of the PD one, assuming certain smoothness conditions. The PD model for viscous flow is calibrated to the classical Navier-Stokes equations by enforcing linear consistency for the viscous stress term. Couette and Poiseuille flows, and incompressible fluid flow past a regular lattice of cylinders …

Ultrathin Coding Metasurface For Underwater Wave Focusing, Branching And Self-Bending Generation With One Single Actuator, Lixie Song, Zhong Chen, Mehrdad Negahban, Lei Liang, Zheng Li, Zheng Wu

Department of Mechanical and Materials Engineering: Faculty Publications

A novel metasurface is proposed that aims to generate underwater acoustic waves with various functions by only one actuator. Each metasurface unit consists of an air cavity sandwiched on one side by a vibration plate and connecting rubber supports. By properly selecting the ratio of the plate to unit lengths, a phase shift of π can be attained to constitute a binary coding metasurface. Three demonstrations, including focusing, branching and self-bending waves, are chosen to validate the functionality of the design. The design is also shown to work over a wide frequency range through changing the ratio. In addition, the …

Machine Learning Assisted Metamaterial‑Based Reconfigurable Antenna For Low‑Cost Portable Electronic Devices, Shobhit K. Patel, Jaymit Surve, Vijay Katkar, Juveriya Parmar

Department of Mechanical and Materials Engineering: Faculty Publications

Antenna design has evolved from bulkier to small portable designs but there is a need for smarter antenna design using machine learning algorithms that can meet today’s high growing demand for smart and fast devices. Here in this research, main focus is on developing smart antenna design using machine learning applicable in 5G mobile applications and portable Wi-Fi, Wi-MAX, and WLAN applications. Our design is based on the metamaterial concept where the patch is truncated and etched with a split ring resonator (SRR). The high gain requirement is met by adding metamaterial superstrates having thin wires (TW) and SRRs. The …

Symmetric Or Asymmetric Glide Resistance To Twinning Disconnection?, Mingyu Gong, Houyu Ma, Kunming Yang, Yue Liu, Jian-Feng Nie, Jian Wang

Department of Mechanical and Materials Engineering: Faculty Publications

Successive gliding of twinning disconnections (TDs) creates three-dimensional twins in parent crystal and accommodates shear deformation. It is generally recognized that TD is subject to the same Peierls stress as it glides forward or backward because of its dislocation character and the twofold rotation symmetry of the twin plane. Based on atomistic simulations, we demonstrate that the glide of TDs may be subject to a symmetric or asymmetric resistance corresponding to step character, symmetric resistance for A/A type steps but asymmetric resistance for A/B type steps, where A and B represent crystallographic planes in twin and matrix. Furthermore, we experimentally …

Recent Advances In Biosensors For Detection Of Covid-19 And Other Viruses, Shobhit K. Patel, Jaymit Surve, Juveriya Parmar, Kawsar Ahmed, Francis M. Bui, Fahad Ahmed Al-Zahrani

Department of Mechanical and Materials Engineering: Faculty Publications

This century has introduced very deadly, dangerous, and infectious diseases to humankind such as the influenza virus, Ebola virus, Zika virus, and the most infectious SARS-CoV-2 commonly known as COVID-19 and have caused epidemics and pandemics across the globe. For some of these diseases, proper medications, and vaccinations are missing and the early detection of these viruses will be critical to saving the patients. And even the vaccines are available for COVID-19, the new variants of COVID-19 such as Delta, and Omicron are spreading at large. The available virus detection techniques take a long time, are costly, and complex and …

A Robot-Assisted Acoustofluidic End Effector, Jan Durrer, Prajwal Agrawal, Ali Ozgul, Stephen C.F. Neuhauss, Nitesh Nama, Daniel Ahmed

Department of Mechanical and Materials Engineering: Faculty Publications

Liquid manipulation is the foundation of most laboratory processes. For macroscale liquid handling, both do-it-yourself and commercial robotic systems are available; however, for microscale, reagents are expensive and sample preparation is difficult. Over the last decade, lab-on-a-chip (LOC) systems have come to serve for microscale liquid manipulation; however, lacking automation andmulti-functionality. Despite their potential synergies, each has grown separately and no suitable interface yet exists to link macro-level robotics with micro-level LOC or microfluidic devices. Here, we present a robot-assisted acoustofluidic end effector (RAEE) system, comprising a robotic arm and an acoustofluidic end effector, that combines robotics and microfluidic functionalities.We …

Mathematical Model Of The Efficiency Of Investments Aimed In The Implementation Of Water-Saving Technologies

Irrigation and Melioration

In Uzbekistan, research work is being carried out aimed at improving the economic mechanisms for the introduction of water-saving technologies for irrigating agricultural crops. At the same time, the issues related to the analysis of the effectiveness of the use of water-saving technologies when irrigating cotton, the development of mathematical methods for assessing the effectiveness of investments, as well as their introduction into practice have not been sufficiently studied. This article provides a mathematical model of the efficiency of investments aimed at introducing water-saving technologies. The results of a numerical experiment of a mathematical model show that the introduction of …

Efficient Use Of Water Resources In The Basins Of Small Rivers, F. Gapparov, M.F. Gafforova

Irrigation and Melioration

The article provides a recommendation for the efficient use of water resources in the basins of small foothill rivers. The research was carried out on the example of the Govasay river basin located in the northern part of the Fergana Valley. The efficiency factor of the canal has been determined and a technical assessment has been given for the management of water resources in the river basin; the efficiency of the canal is 65-75%. A program for the operational management of water resources in The Govasay river basin and a GIS map of water consumers in the Govasay river basin …

Model Of Groundwater Level Control Using Horizontal Drainage, A. Arifjanov, M. Otaxonov, Z. Abdulkhaev

Irrigation and Melioration

The article describes the main factors affecting the rise in the level of groundwater in the city of Fergana and ways to eliminate them. Currently, in order to reduce the negative impact of rising groundwater levels on the environment, crops, buildings and structures, as well as underground utilities, it is proposed to design horizontal drainage in urban areas and a mathematical model has been developed for changing the groundwater level. For this, long-term data from observation wells were analyzed and the hydraulic parameters of horizontal drainage were selected taking into account the hydrogeology of the area. Taking into account the …

Results Of Proximate Analysis Of Energy Use Of Municipal Solid Waste, N.N. Abduganiev

Irrigation and Melioration

In the modern industrialized world, various raw materials are processed and used for human consumption. While some of the raw materials are converted into the desired product, the rest is thrown into the environment as waste. It is known that solid waste is a type of biomass that is formed in the course of human life. The article presents the results of a preliminary analysis of studies on the use of solid waste energy in the Urta-Chirchik district of the Tashkent region. Sorting results showed that the total volume of municipal solid waste in the district consists mainly of wood …

Shredding Of Cotton Stalks Under The Action Of Toothpicks In A Combined Unit, B. Khudayarov, U. Kuziev, B. Sarimsakov, М. Kholbutaev

Irrigation and Melioration

The article presents materials devoted to the justification of the parameters of the crown-wheel of the combined aggreagate. The technological process of work and the design of the working part, which is crushed by crushing cotton stalks, without breaking them, laying them on the movement of the unit, has been substantiated and developed. The optimal parameters of the crown-wheel and the tooth are determined by solving the regression equations that determine the optimal values of the vertical load on the teeth and its working quality. The results of theoretical and experimental research show that the amount of crushing of cotton …

Influence Of Electrophysical Methods On The Processes Of Root Formation Of Grapes, N.M. Markayev

Irrigation and Melioration

The article describes the possibilities of electrophysical processing before planting cuttings during vegetative cultivation of grape seedlings. The processes of root formation in cuttings using the electrophysical method in the article Acceleration of the process of root formation in cuttings of black raisins, treated at 71 V/m and an electric field strength of 15 hours, and an increase in the viability, quality, growth and survival of rooted seedlings up to 16.67-34% Presented the results of experiments on the increase and methods of electrotechnological processing of grape cuttings. The result of the study is the analysis and results of the processes …

Conditions, Criteria And Principles For Creating An Agri-Cultural Land Market In Uzbekistan, A.R. Nurnazarov

Irrigation and Melioration

The article analyzes the prerequisites for creating a market for agricultural land in the Republic of Uzbekistan, special attention is paid to land reform, land degradation (reduction of the bonitet score from 60 in 1991 to 50 or more at present, pasture degradation by 20-30%) and increase in economic from their use, the role of land rent in payments for land. 6 basic principles for creating a land market have been established and systematized, the relationship between X-rays and water in the irrigated farming zone, the role of the market in increasing the efficiency and effectiveness of the use of …

Economic Assessment Of The Effect Of Family Income On Students' Disciplines, Sh.A. Muratov

Irrigation and Melioration

The importance of higher education in scientific research, its role in poverty reduction and population growth has been studied theoretically. Also, when using the data of social surveys conducted by 538 respondents (students) studying in higher education institutions, they were awarded the Order of the logistics regulator in the economic assessment of the factors influencing the rate of mastery of disciplines. Factors influencing the acquisition of subjects by students: the main income of the family comes from non-farm (69,9 %), sex (52,2 %), studying at a higher education institution on a state grant (108,8 %), the student's course of study …

Innovative Rotor Casing And Leveling Apron For Combined Tillage Machine, A.A. Akhmetov, L.B. Muratov

Irrigation and Melioration

Investigations of the design of a combined machine equipped with an innovative casing and a leveler apron are presented, and the parameters of the leveler apron are substantiated. It was experimentally established that when the height of the drawing prism is exceeded by more than 200 mm, due to the falling of the crumbling part of the soil onto the rotor, the soil is thrown forward in the direction of the machine. Therefore, to eliminate soil waste, it is necessary either to reduce the height of the drag prism, or to increase the distance between the rotor and the leveling …

Ensuring The Uniformity Of Movement Of The Working Bodies Of The Machine For Processing Ridges In The Depth Of Travel, А. Tukhtakuziev, K.G. Abdulkhaev

Irrigation and Melioration

The article theoretically investigates the issue of identifying ways to ensure the deepening of the working bodies of the machine for processing ridges to a given processing depth and its required uniformity of stroke. The research results show that the deepening of the working bodies of the ridges processing machine to a given processing depth and its required uniformity is provided mainly due to the correct choice of the vertical distance from its reference plane to the lower connection points. The novelty of the conducted research lies in the fact that an analytical dependence has been obtained that allows us …

Develepment Of Land Market In Eastern European Countries And Experience For Uzbekistan, A.R. Nurnazarov

Irrigation and Melioration

The article examines the experience of the formation of the agricultural land market in Eastern European countries since the 90 s of the twentieth century, the problems and features of its devel-opment, the impact of the land market on the economies of countries. Particular attention is paid to the transformation of land ownership, methods of land privatization, land pricing, restrictions on land purchase, regulation of land relations in market conditions, issues of granting the right to pur-chase land to foreign individuals and legal entities, requirements for land owners for the presence of a special agricultural education or 3-5 years of …

The Developmet Of Competences Via Techniques For Enhancing Esp (English For Specific Purposes) Vocabulary Of Learners, G. Eshchanova

Irrigation and Melioration

In the article a recent trend in higher education is ESP (English for Specific Purposes) courses is discussed. These courses are designed around students’ needs based on their field of study. The goal is to strengthen students’ proficiency and help them to get ready to cope with everyday situations and deal with professionals in many fields such as: engineering, medicine, education and IT. There are many training sessions organized by international experts whose goal is to train local teachers to teach these courses successfully. In order to develop an ability to learn new vocabulary, for both general English and technical …

Development Of Girls’ Sports, A.R. Khodjanov, V.V. Mahmudov

Irrigation and Melioration

The article addresses current issues of higher education, taking into account its specifics. She has been providing appropriate advice on improving girls' physical well-being. The use of opportunities and qualities has an impact on the creation of comfortable conditions for female athletes. For girls involved in sports, the creation of impressive quality and possible conditions is considered. As a result, the girls-athletes of our institute took 2-3 places in the district and city qualifying rounds of chess, table tennis and won a ticket to the republican stage. At the republican stage, 2 female students of our team took 4th place …