Engineering Commons^™

Features Designing Special Clothing For The Hot Climate Of Uzbekistan, N Kh Mirtalipova, N A. Isaxujayeva

Technical science and innovation

This paper considers the issues of establishing the relationship between the properties of fabric, clothing design and the comfort of clothing; communication of the size of the human body, allowance for free fitting, modern design when developing the design of clothing; connection of the allowance for free fitting with a suitable air gap. A diagram is given that characterizes the dependence of the comfort of clothing on its design and properties of fabrics. A mathematical model of the processes of air exchange in the underwear space is considered, which will allow obtaining more complete information and establishing more stringent dependences …

Austenitic, Duplex, And Lean Duplex Stainless Steel Critical Pitting Temperature In Simulated Concrete Environment, Bobby Giebel

Williams Honors College, Honors Research Projects

In this work, the critical pitting temperature (CPT) will be observed for a selection of austenitic (316LN and 24100) and duplex (2205), and lean duplex (2304, 2001) stainless steels in simulated concrete pore solution. To study the influence of temperature on the pitting stability of the stainless steels, three temperatures were tested: 25oC, 45oC, and 65oC for cyclic potentiodynamic polarization (CPP) and electrochemical impedance spectroscopy (EIS). Electrochemical properties of the interfaces we studied via EIS analysis. Kinetics were studied via CPP testing. To reveal the critical pitting temperature of the stainless steels, cyclic thermammetry was used. Characterization of the pits …

Development Of Preparations Based On Local Components For Dust Suppression On Quarry Roads, Olikulov Fakhriyor, Mukhiddinov Bakhоdir, Vapoev Khusniddin, Zhurayev Shokhruh

CHEMISTRY AND CHEMICAL ENGINEERING

The aim of the work is to develop dust-collecting preparations based on local raw materials for the suppression of man-made dust formed on quarry paths. For this purpose, 4 types of the drug were created in the laboratory on the basis of domestic raw materials for dust suppression. The dependence of the viscosity and density of the created preparations on the concentration of components and temperature is studied. For the preparation of the solution of the created drug, a semi-industrial installation is created, which presents the general view and the process of preparing the solution. The spray of the prepared …

Synthesis And Spectroscopic Study Of Complex Compounds Of Mn(Ii), Co(Ii), Ni(Ii), Cu(Ii) And Zn(Ii) Acetates With 2-Aminobenzimidazole, Gapurova Lobar, Kadirova Shakhnoza, Rakhmonоva Dilnoza, Olimova Manzura

CHEMISTRY AND CHEMICAL ENGINEERING

The aim of the work is to develop a synthesis procedure and obtain new complex compounds of transition metal acetates with 2-aminobenzimidazole (L), to study the composition and structure of the synthesized compounds by elemental, thermal, X-ray phase analysis and IR spectroscopy. A procedure for the synthesis of new complex compounds of Mn(II), Cо(II), Ni(II), Cu(II) and Zn acetates with 2-aminobenzimidazole was developed and the composition and structure of the synthesized complex compounds were studied using modern physicochemical methods. Coordination competing donor centers, electronic and geometric structures of the ligand molecule were studied on the basis of a quantum-chemical calculation …

Specific Features Of Optical Fiber Cable Operation During Tension And Change Of Ambient Temperature, Dilmurod Davronbekov, Zafar Khakimov

Bulletin of TUIT: Management and Communication Technologies

This article examines the effect of longitudinal and thermoelastic deformation of an optical module on the technological reserve of an optical fiber. Analytical expressions are given for determining the lower limit of the technological margin of an optical fiber for various types of fiber-optic cable section along the axis.

Influence Of Technological Parameters On The Chemical Composition Of Calcium Polyphosphates From Phosphorites Central Kyzylkum, Ulugberdieva Ziyada, Khujamberdiev Sherzod, Mirzakulov Kholtura, Usmanov Ilkham

CHEMISTRY AND CHEMICAL ENGINEERING

The aim of the research was to study the effect of temperature, the ratio of P2O5EPA:P2O5PRM and the duration of calcination on the content of various forms of P2O5 in calcium polyphosphate. The effect of calcination temperature from 150 to 300 °C, the ratio of P2O5EPA:P2O5FRM from 2,15 to 4,50 and the duration of the process from 20 to 120 minutes on the changes in various forms of P2O5 were studied. It was shown that with increasing temperature to 200-250 °C the content of the total (ortho + poly) assimilable form of Р2О5 increases and then decreases, passing through a …

Influence Of Technological Parameters On The Chemical Composition Of Calcium Polyphosphates From Phosphorites Central Kyzylkum, Ulugberdieva Ziyada, Khujamberdiev Sherzod, Mirzakulov Kholtura, Usmanov Ilkham

CHEMISTRY AND CHEMICAL ENGINEERING

The aim of the research was to study the effect of temperature, the ratio of P2O5EPA:P2O5PRM and the duration of calcination on the content of various forms of P2O5 in calcium polyphosphate. The effect of calcination temperature from 150 to 300 °C, the ratio of P2O5EPA:P2O5FRM from 2,15 to 4,50 and the duration of the process from 20 to 120 minutes on the changes in various forms of P2O5 were studied. It was shown that with increasing temperature to 200-250 °C the content of the total (ortho + poly) assimilable form of Р2О5 increases and then decreases, passing through a …

The Effect Of Cryogenic Thermal Cycling On Aging, Rejuvenation, And Mechanical Properties Of Metallic Glasses, Nikolai V. Priezjev

Mechanical and Materials Engineering Faculty Publications

The structural relaxation, potential energy states, and mechanical properties of a model glass subjected to thermal cycling are investigated using molecular dynamics simulations. We study a non-additive binary mixture which is annealed with different cooling rates from the liquid phase to a low temperature well below the glass transition. The thermal treatment is applied by repeatedly heating and cooling the system at constant pressure, thus temporarily inducing internal stresses upon thermal expansion. We find that poorly annealed glasses are relocated to progressively lower levels of potential energy over consecutive cycles, whereas well annealed glasses can be rejuvenated at sufficiently large …

Generator Design: A Study Of Optimized Airflow, Rachel Wattleworth

Williams Honors College, Honors Research Projects

The core goal of this project was to prototype, test, and evaluate a new type of fan for the Safran Electrical & Power air-cooled generators. The idea of a new fan being made for these two generators arose when they were not adhering to design requirements. A base mixed-flow fan was created to test on multiple generators. Upon creating a prototype, it will be tested to prove if it can increase the air flow, decrease temperatures, and increase power and life of the machines. They all proved to be successful and achieve the main objectives for this project. Data such …

Elevated Temperature Progressive Damage And Failure Of Duplex Stainless Steel, Darren P. Luke

Civil Engineering ETDs

Ductile failure of metals has been the focus of research efforts within academia and industry for many years since it is tremendously important for understanding the failure of structures under extreme loading conditions. However, limited research has been dedicated to elevated temperature ductile failure, which is critical for evaluating catastrophic events such as industrial, structural or shipping vessel fires. A detailed investigation was conducted on the structural response of Duplex Stainless Steel at elevated temperatures. The temperature dependence of elastic modulus, yield strength, ultimate strength, and ductility was measured up to 1000°C and a continuum damage plasticity model was developed. …

Slow Relaxation Dynamics In Binary Glasses During Stress-Controlled, Tension-Compression Cyclic Loading, Nikolai V. Priezjev

Mechanical and Materials Engineering Faculty Publications

The effect of cyclic loading on relaxation dynamics and mechanical properties of metallic glasses is studied using molecular dynamics simulations. We consider the Kob-Andersen three-dimensional binary mixture rapidly cooled across the glass transition and subjected to thousands of tension-compression cycles in the elastic range. It was found that during cyclic loading at constant pressure, the system is relocated to progressively lower levels of the potential energy, thus promoting greater densification and higher strength. Furthermore, with increasing stress amplitude, the average glass density increases and the minimum of the potential energy becomes deeper, while the elastic modulus is reduced. The typical …

The Yielding Transition In Periodically Sheared Binary Glasses At Finite Temperature, Nikolai V. Priezjev

Mechanical and Materials Engineering Faculty Publications

Non-equilibrium molecular dynamics simulations are performed to investigate the dynamic behavior of three-dimensional binary glasses prepared via an instantaneous quench across the glass transition. We found that with increasing strain amplitude up to a critical value, the potential energy approaches lower minima in steady state, whereas the amplitude of shear stress oscillations becomes larger. Below the yielding transition, the storage modulus dominates the mechanical response, and the gradual decay of the potential energy over consecutive cycles is accompanied by reduction in size of transient clusters of atoms with large nonaffine displacements. In contrast, above the yield strain, the loss modulus …

Simulation Analysis In Dynamic Performance Of Proton Exchange Membrane Fuel Cell Under Starting Condition, Yan Xiao, Ying-Jie Chang, Wei Zhang, Qiu-Hong Jia

Journal of Electrochemistry

Based on the equivalent circuit model, by considering both the dynamic gas pressure model and the dynamic heat transfer model, a lumped parameter model is developed. The start process of the fuel cell is simulated by using SIMULINK software. The undershoot of the voltage is observed from the simulation results, and the response time of the voltage is basically the same as that of the fuel cell temperature, which indicates that the temperature has great influence on the dynamic performance of the fuel cell. From the perspective of the temperature, the dynamic responses of the thermodynamic potential, the activation overvoltage, …

Effects Of Temperature On The Nucleation And Growth Mechanism Of Pbo2 Electrodeposition, Lei Wang, Juan-Qin Xue, Li-Hua Yu, Chang-Bin Tang, Qiang Bi

Journal of Electrochemistry

In order to investigate the effects of temperature on the nucleation and growth of lead dioxide (PbO₂)， the in situ electrochemical depositions of PbO₂ were carried out on the glassy carbon electrode at different temperatures, namely, 25℃,35℃, 45℃, 55℃, and 65℃.The cyclic voltammetric curves, the time-current and the time-potential curves，SEM images and XRD patterns of the PbO₂ coatings deposited at different temperatures were obtained. The results showed that the PbO₂ underwent nucleation and grew at different temperatures. The 3D continuous nucleation mode of PbO₂ electrodeposition remained unchanged with the increase of temperature. However, the …

A Study Of Corrosion Monitoring Techniques Used In Urls For Metals, Sirui Li

USF Tampa Graduate Theses and Dissertations

With the increasing use of fission-type nuclear power generation, particularly high-levels radioactive nuclear waste are generated, so the safe use of nuclear energy requires proper disposal of high-level radioactive nuclear waste. The selected treatment method is deep geological disposal. Therefore, underground research laboratory (URL) to prepare for deep geological disposal will also be carried out. Corrosion of metallic materials, which are closely related to the safety of URL, is the focus of this research project. This study selected monitoring techniques for URL and developed a rough monitoring scheme for temperature and resistivity in URL. In this study, corrosion-temperature and corrosion-resistivity …

Degradation Of High Performance Polymeric Fibers: Effects Of Sonication, Humidity And Temperature On Poly (P-Phenylene Terephthalamide) Fibers, Nelyan Lopez-Perez

Open Access Theses

High performance fibers are characterized by properties such as high strength and resistance to chemicals and heat. Due to their outstanding properties, they are used on applications under harsh environments that can degrade and decrease their performance. Fiber degradation due to different chemical and mechanical factors, is a process that begins at a microstructural level. Changes in the polymer’s chemical or physical structure can alter their mechanical properties. Knowledge of the structure-properties relationship and the effects of environmental chemical and physical factors over time, is crucial for the improvement and development of high performance fibers.

In this study ballistic fibers …

Oxidation Resistance Of Nanocrystalline 316l Stainless Steel Processed By High Pressure Torsion, Kevin J. Meisner

Williams Honors College, Honors Research Projects

High Pressure Torsion (HPT) is a materials processing method used to refine the grain size of metallic materials through the application of simultaneous axial and torsional strain. HPT is reported to result in nanocrystalline structure, which the current scientific literature suggests may improve the high temperature oxidation resistance by enhancing diffusion of solutes, particularly Cr, to the surface to form a protective external oxide scale. If oxidation resistance is improved, this possibly allows the use of 316L in oxidizing environments where more expensive alloys are typically used. However, the influence of grain refinement to nanoscale on various properties have been …

Simulation Study Of Hemt Structures With Hfo2 Cap Layer For Mitigating Inverse Piezoelectric Effect Related Device Failures, Deepthi Nagulapally, Ravi P. Joshi, Aswini Pradhan

Electrical & Computer Engineering Faculty Publications

The Inverse Piezoelectric Effect (IPE) is thought to contribute to possible device failure of GaN High Electron Mobility Transistors (HEMTs). Here we focus on a simulation study to probe the possible mitigation of the IPE by reducing the internal electric fields and related elastic energy through the use of high-k materials. Inclusion of a HfO₂ "cap layer" above the AlGaN barrier particularly with a partial mesa structure is shown to have potential advantages. Simulations reveal even greater reductions in the internal electric fields by using "field plates" in concert with high-k oxides

Influence Of The Temperature On Flow-Induced Crystallization Of Isotactic Polypropylene And Propylene-Ethylene Random Copolymer, Hugo Boitout

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

When flow is applied on a semi-crystalline polymer melt, it can greatly impact how it crystallizes its final properties. Therefore, it is crucial to understand the basic mechanism of flow induced crystallization (FIC). Only then will it be possible to predict final properties from the type of resin and processing conditions. Polypropylene is one of the most widely used polymers. Its processing generally involves subjecting the melt to intense flow fields, so FIC commonly occurs.

This study investigates the influence of temperature of shear and crystallization on the FIC behavior of isotactic polypropylene (iPP). Temperature is one of the main …

Temperature And Alloying Effects On The Mechanical Properties Of Equiatomic Fcc Solid Solution Alloys, Zhenggang Wu

Doctoral Dissertations

Compared to decades-old theories of strengthening in dilute solid solutions, the mechanical behavior of concentrated solid solutions is relatively poorly understood. A special subset of these materials includes alloys in which the constituent elements are present in equal atomic proportions, including the high-entropy alloys of recent interest. A unique characteristic of equiatomic alloys is the absence of “solvent” and “solute” atoms, resulting in a breakdown of the textbook picture of dislocations moving through a solvent lattice and encountering discrete solute obstacles. To clarify the mechanical behavior of this interesting new class of materials, we investigate here a family of equiatomic …

Evaluation Of Alternate Mouthpiece Material Types To Minimize Vibrations And Heat Loss - The Research And Execution Of Prototypes, Kristen Bobuk

Theses, Dissertations and Capstones

This paper is based on the idea of current horn mouthpieces being made solely out of brass with a limited market of stainless steel and titanium with plating being silver or gold. This is an opportunity to explore alternate materials; specifically steel, cast iron and aluminum for the base material and chrome, copper and nickel for plating materials. Readers will learn about metal properties such as hardness, thermal conductivity and specific heat and learn why certain materials are more beneficial than others.

Irrigation Leak Detection: Using Flow Rate Sensors To Detect Breaks In An Irrigation System, Adam Openshaw, Kalvin Vu

Computer Engineering

This report details the exploration and invention of a mechanism that can detect breaks in an irrigation system. With the ultimate goal of conserving water, we have designed an inexpensive, self sustaining flow rate monitor that can be used to identify anomalies in an irrigation system and wirelessly communicate the status of the system to a base station. Our implementation can also determine the direction of the anomaly based on the nature of the anomaly itself. This means that multiple monitors can be used to pinpoint the location of a break within the system in addition to merely detecting its …

Environment-Induced Degradations In A Target Structural Material For Transmutation Applications, Ramprashad Prabhakaran

UNLV Theses, Dissertations, Professional Papers, and Capstones

This investigation is focused on the evaluation of stress corrosion cracking (SCC) and localized corrosion behavior of Type 422 stainless steel in aqueous environments at ambient and elevated temperature. The results of constant load SCC testing using smooth specimens showed no failure in the neutral solution but a threshold stress of 97 ksi was observed in the 90°C acidic environment. SCC testing by the slow-strain-rate test method indicate that the time-to-failure, true failure stress and ductility parameters were gradually reduced with increasing temperature, showing more pronounced effect in the acidic solution. The application of a controlled cathodic potential showed further …

Temperature, Stress, And Corrosive Sensing Apparatus Utilizing Harmonic Response Of Magnetically Soft Sensor Element (S), Craig A. Grimes, Keat Ghee Ong

Chemical and Materials Engineering Faculty Patents

A temperature sensing apparatus including a sensor element made of a magnetically soft material operatively arranged within a first and second time-varying interrogation magnetic field, the first time-varying magnetic field being generated at a frequency higher than that for the second magnetic field. A receiver, remote from the sensor element, is engaged to measure intensity of electromagnetic emissions from the sensor element to identify a relative maximum amplitude value for each of a plurality of higher-order harmonic frequency amplitudes so measured. A unit then determines a value for temperature (or other parameter of interst) using the relative maximum harmonic amplitude …

Influence Of Strain Rate And Temperature Of Hot Tension Testing On Mechanical Properties Of Medium Carbon Steel S48c, Dedi Priadi, Iwan Setyadi, Eddy S. Siradj

Makara Journal of Technology

Influence of Strain Rate and Temperature of Hot Tension Testing on Mechanical Properties of Medium Carbon Steel S48C. The characterization of S48C by hot tension testing was done to understanding the influence of temperature and strain rate for S48C flow stress, that close relationship with its forge ability. The hot tension testing was performed on temperatures and strain rates variation (T 850, 900, 950 0C and έ 0,01;1 s-1). The result of hot tension testing showed that increasing temperature decreases ultimate tensile strength (UTS) and flow stress of S48C. The higher decreasing of UTS is on 950 0C about 85% …

Remote Magneto-Elastic Analyte, Viscosity And Temperature Sensing Apparatus And Associated Methods Of Sensing, Craig A. Grimes, Plamen G. Stoyanov

Chemical and Materials Engineering Faculty Patents

An analyte, viscosity, or temperature sensing apparatus for operative arrangement within a time-varying magnetic field, including a sensor with an outer surface that is chemically, frictionally, or thermally responsive and adhered to a base magnetostrictive element, and a receiver to measure a first and second value for magneto-elastic emission intensity of the sensor taken at, respectively, a first and second interrogation frequency. A change in mass or a change in material stiffness of the sensor due to the responsiveness, the viscosity and mass density of a fluid therearound, or the temperature, can be identified. The receiver, alternatively, measures a plurality …

Effects Of 0.25 % Mo (Molybdenum) Which Is Contained In The Ductile Cast Iron On Mechanical Properties Of Austempered Ductile Iron (Adi)., Nukman Nukman, Bustanul Arifin, Bambang Sugiarto

Makara Journal of Technology

The aim of this research is to investigate the effects of 0.25 % Mo (Molybdenum) which is contained in the ductile cast iron on mechanical properties of Austempered Ductile Iron (ADI). The various temperatures and the holding times are used in the heat treatment processes. Using a given 0.25 % Mo in the ductile iron, ADI's alloyed developes a higher ultimate tensile stress value and decreases the elongation if we compare with the as cast (non alloy ductile iron). The higher impact energy value obtained at 9000 C austenization and 375o C austempering temperatures during 60 minutes holding times. The …

An Experimental Study Of Molten Microdroplet Surface Deposition And Solidification: Transient Behavior And Wetting Angle Dynamics, Daniel Attinger, Z. Zhao, D. Poulikakos

Daniel Attinger

The basic problem of the impact and solidification of molten droplets on a substrate is of central importance to a host of processes. An important and novel such process in the area of micromanufacturing is solder jetting where microscopic solder droplets are dispensed for the attachment of microelectronic components. Despite the recent appearance of a few numerical studies focusing on the complex transient aspects of this process, no analogous experimental results have been reported to date to the best of our knowledge. Such a study is reported in this paper. Eutectic solder (63Sn37Pb) was melted to a preset superheat and …

The Effects Of Acid Concentration On The Current Efficiency During The Electrolysis Of Zinc Sulfate Solution, Jon Langfeldt

Bachelors Theses and Reports, 1928 - 1970

The current efficiency during the electrolysis of zinc sulfate solution and the various factors that effect the current efficiency are major considerations of this industrial process. The factors affecting current efficiency-- temperature, current density, presence of impurities, time of electrolysis, hydrogen overvoltage, smoothness of the deposit, and acid concentration of the cell solution-- are controlled to the extent that current efficiencies of 90-93% are not uncommon in the industrial electrolytic zinc process. However, additional investigations of the effects of these various factors upon current efficiency are warranted, because of the endless search by the non-ferrous metal industries for additional information …