bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of Inlet Curved Disk Arrangements for Suppression of Recirculation in Centrifugal Pump Impellers
Authors: Hermez Munther Y. , Jawad Badih A. , Liu Liping , Fernandez Vernon , Yee Kingman , Oklejas Eli 
Published: February 2017

The present work aims to numerically study the inlet flow recirculation and modified impeller interaction in a centrifugal pump. An optimization of modified shrouded impeller with curved disk arrangement to suppress the unsteady flow recirculation is pursued. This modification will enhance the impeller characteristics with a wider operation range at both low and high flow rates in a high speed centrifugal pump type. The unstable flow in the centrifugal pumps is a common problem that leads to damage in the pump’s internal parts, consequently increases the operating cost. At certain flow rates, generally below the Best Efficiency Point (BEP), all centrifugal pumps are subject to internal recirculation occurs at the suction and discharge areas of the impeller.
For decades, experimental work has been done to investigate the complex three-dimensional flow within centrifugal pumps impellers, before computational work gains momentum due to advancement of computing power and improved numerical codes. In this study the impeller with a curved disk arrangement has been investigated by using a three-dimensional Navier-Stokes code with a standard k-ε turbulence model. The purpose is to evaluate and select the optimum impeller modification that would increase the pump suction flow rate range. Three-dimensional numerical Computational Fluid Dynamics (CFD) tools are used to simulate flow field characteristics inside the centrifugal pump and provide critical hydraulic design information. In the present work, ANSYS v.16.1 Fluent solver is used to analyze the pressure and velocity distributions inside impeller suction and discharge passages.
The ultimate goal of this study is to manufacture and validate the most optimized and efficient centrifugal pump impeller with a curved disk. The best case curve identifies the highest increase of total pressure difference by 22.1%, and highest efficiency by 92.3% at low flowrates.
Acquiring Embodied Knowledge Through Practice: A Wisdom Engineering Approach
Authors: Fukuda Shuichi 
Published: February 2017

Although remarkable progress has been made in the field of explicit knowledge, research about tacit knowledge is still very few. This paper takes up embodied knowledge such as bicycle riding, as one kind of tacit knowledge. As embodied knowledge cannot be articulated and verbalized, it has to be transferred to another person through practice. But how we can acquire embodied knowledge more effectively through practice is still the question at issue.
Indeed, there are works to help a learner to acquire embodied knowledge by showing the videos or through OJT. But since features or control points are not explicit, it is very difficult for a learner to acquire a good sense for judgments and for decisions to cope with the changing situations.
Although there are many approaches to multivariate analysis, there are very few approaches which provide a holistic perspective. In this sense, pattern-based approach is better than other approaches.
This paper points out that pattern-based Recognition Taguchi (RT) approach in Mahalanobis Taguchi System (MTS) is expected to be a very promising and versatile tool to help a learner acquire embodied knowledge because it allows us to take the differences of body behavior from person to person in addition to providing the holistic perspective.
Thermal Gradient on Hybrid Composite Propellant Tank Materials at Cryogenic Temperatures
Authors: Avila Raudel O. , Islam Md S. , Prabhakar Pavana 
Published: February 2017

Cryogenic tanks are devices that are commonly used to store extremely low temperature fluids, usually in their liquid state. Cryogenic fuel tanks carry cryogenic propellants such as liquid oxygen, liquid methane or liquid hydrogen, at subfreezing temperatures in its condensed form in order to generate highly combustible liquids. This type of tank is exposed to an extremely cold temperature in its interior and to ambient temperature on its external surface resulting in large temperature gradient across the thickness of the wall. In this paper, hybrid textile composites with carbon and Kevlar® fabric are explored as means to reduce the influence of thermal gradient in order to enhance the material performance when cryogenic propellant fuels are stored in spacecraft applications.
Previous initial studies of tensile and flexural tests have indicated that carbon and Kevlar® textile composites are suitable materials for cryogenic temperatures. The pristine mechanical properties of carbon composites changed within a maximum of 3–4% after initial cryogenic exposure during the fueling stage, while 17% for Kevlar® composites. Computational models of hybrid carbon-Kevlar® composites were subjected to cryogenic temperature (77 K) to investigate the effect of exposure for extended periods and to aid in the design of optimum layups for the same. Six optimal combinations were selected that resulted in low interface stresses and lower number of peak stresses through the thickness of the laminate. These layups were deduced to perform better compared to other layups due to lesser susceptibility to delamination type failure upon cryogenic exposure. Experimental investigation of the chosen hybrid composites has revealed few optimum combinations for use in tanks. As a next step, computational analysis of cryogenic exposure to only one surface of hybrid composites was performed to simulate the composite wall containing the liquid fuel. Based on the suggestions from the computational models, experiments to determine optimum designs of the composite wall were conducted. An ABS plastic insulating holder was computationally designed and 3D printed to hold the specimens such that only one surface is exposed to LN2. A total of eight composite layups were exposed to liquid nitrogen using the plastic holder to study their response to thermal gradient cryogenic exposure. Based on the results obtained computationally and supported by experiments, optimum hybrid layups of composites to sustain cryogenic exposure were determined.
Synthetic and Organic Supercharger Lubrication: The Tribological Performance of Ionic Liquids as Additives to Lubricants
Authors: Bain Derek , Fisk Dana , Gomez Serrano Camila , Orlando Samantha , Iglesias Patricia 
Published: February 2017

A supercharger is a mechanical device that can be added to an engine of a car to increase engine power. It works by sucking air in at atmospheric pressure into the rotors and compressing it at high revolutions per minute. With the rotors spinning at high speeds, the supercharger gears are exposed to high values of friction and wear, which results in a reduction of their service life.
Ionic liquids (ILs) are substances that possess unique lubricating abilities when added to base oil or when used as neat lubricants. Properties include low volatility, non-flammability, as well high thermal resistance. These liquids are able to form ordered layers and tribofilms on the contacting surfaces which further protects the surface materials. In this work, the effect of adding ILs to low viscosity synthetic oil used to lubricate gears and to organic oil was investigated in the reduction of friction and overall wear of superchargers. Mobil 1 5W-30 Full Synthetic Engine Oil (MS) was used as a control and compared to coffee bean oil (CB). Additionally, the performance of these oils was observed with ionic liquids as additives at 1 wt. %. The chosen IL consisted of the cation Trihexyltetradecylphosphonium, [P6,6,6,14]+, with the anion Bis(trifluoromethylsulfonyl) amide, [NTf2]−. Lubricated flat disks of AISI 52100 stainless steel and 420C steel balls were studied using a Pin-on-Disk configuration. A total sliding distance of 500 meters was tested with a wear track diameter of 20 mm. Wear volume and average friction coefficient were measured according to ASTM-G99. Results showed that the addition of the ILs to the CB and MS reduced friction coefficient of the steel disks at medium speeds, and wear values achieved were comparable to the friction observed. The wear width values were also found to be reduced at medium speeds.
A Study of Shape Optimization Method on Connection Cones for Diesel Particulate Filter (DPF)
Authors: Mu Mingfei , Li Xinghu , Aslam Jawad , Qiu Yong , Yang Hao , Kou Guiyue , Wang Yan 
Published: February 2017

For diesel vehicles equipped with a Diesel Particulate Filter (DPF), flow resistance (pressure drop) is a vital factor affecting power performance, fuel consumption and regeneration performance. Traditional methods for DPF pressure drop reduction mainly focus on developing a new filter material, optimizing its microstructure and structural parameters of gas channels. Although the above methods have greatly reduced the pressure drop, it is still difficult to meet the demand of increasingly stringent energy consumption and carbon emissions standards. Thus, improving the shape of connection (inlet and outlet) cones to further reduce pressure drop has become one of the important topics of DPF development.
In this paper, a simulation model of gas-particle two-phase flow through traditional connection cones has been established and wall-flow filter element is modeled with an equivalent porous material. The flow through DPF has been simulated with Fluent computational fluid dynamics (CFD) software under different exhaust emission velocities, expansion angles and ratios. The influence factors for flow uniformity and pressure drop in DPF have been analyzed. The variation tendency of pressure drop, flow velocity, vorticity, and turbulent kinetic energy in connection cones has been obtained. And then, based on calculation results and Non-Uniform Rational B-Splines (NURBS) theory, the fitting cure of optimum connection cones are drawn out at different expansion angles and ratios, compared with the calculation results of traditional connection cones, to deduce advantages of optimum connection cones on the flow uniformity and pressure drop.
Energy Optimization of Air Handling Unit Using CO2 Data and Coil Performance
Authors: Razban Ali , Edalatnoor Arash , Goodman David , Chen Jie 
Published: February 2017

Air handling unit systems (AHU) are the series of mechanical systems that regulate and circulate the air through the ducts inside the buildings. In a commercial setting, air handling units accounted for more than 50% of the total energy cost of the building in 2013. To make the system more energy efficient without compromising comfort, it is very important for building energy management personnel to have tools to monitor the system performance and optimize its operation. Models are needed to meet the needs. The objectives of this study were to (1) develop models for the AHU elements and (2) implement control strategies to improve energy efficiency without sacrificing room comfort based on the published American Society of Heating Refrigeration and Air Conditioning Engineers (ASHRAE) standard.
In this study, algorithms were developed to model the energy usage for heating/cooling coils as well as fans for AHU. Enthalpy based effectiveness and Dry Wet coil methods were identified and compared for accuracy of evaluating the system performance. Two different types of control systems were modeled and the results were shown based on occupancy reflected by the collected the rooms’ CO2 data. Discrete On/Off and fuzzy logic controller techniques were simulated using Simulink Matlab software and compared based on energy reduction and system performance.
The models were used on an AHU in one of the campus buildings. The data for model inputs were collected wirelessly from the building using fully function devices (FFD) and a pan coordinator to send/receive the data. Current building management system Metasys software was also used to get additional data. The AHU modeling was done using Engineering Equation Solver (EES) Software for the coils and subsystems. Moving Average technique was utilized to process the data.
The models were validated by comparing the calculated results with these measured experimentally. Simulation results showed that in humid regions, where there is more than 45% of relative humidity, the dry wet coil method is the effective way to provide more accurate details of the heat transfer and energy usage of the AHU comparing to the enthalpy based effectiveness.
Also results of fuzzy logic controller method show that 62% of the current return fan energy can be reduced weekly using this method without sacrificing the occupant comfort level comparing to the ON/OFF method. Energy consumption can be optimized inside the building using fuzzy logic controller. At the same time system performance can be increased by taking the appropriate steps to prevent the loss of static pressure in the ducts.
The implementation of the method developed in this study will improve the energy efficiency of the AHU while the occupants comfort level stay intact.
Screw Rotor Profiles of Variable Lead Vacuum and Multiphase Machines and Their Calculation Models
Authors: Stosic Nikola , Rane Sham , Kovacevic Ahmed , Smith Ian K. 
Published: February 2017

Twin screw machines are mechanically simple and reliable, having only two moving parts, while their manufacturing cost is low and, as a result of optimization of their rotor proportions and profiles, their efficiency is high. Consequently, they are now used widely both as multiphase and vacuum pumps.
This study gives the results of an investigation of how their performance is affected by changing the rotor lead, i.e. the axial step along the rotor wrap, from a constant value to a variable one. A number of different configurations have been considered and it is shown that, for machines with a large wrap angle, a variable lead results in greater displacement and improved efficiency.
Review of Solar Sorption Cooling Research in the MENA Region
Authors: Mohammad Iqbal Abdul Ahad , Al-Alili Ali 
Published: February 2017

This paper provides a brief overview of closed sorption cooling technologies, and highlights the research performed on them in the Middle East and North Africa region. The main findings are summarized and presented in tabulated and graphical forms. The reviewed studies are compared in terms of the working pair, the Coefficient of Performance, the normalized collector area, etc. The results show that the average cyclic Coefficient of Performance for the adsorption chillers was 0.41, whereas the average chiller Coefficient of Performance for the absorption chillers was 0.677.
The research trends reveal that interest in solar sorption cooling was low in the 1980s and 1990s, and gradually increased during the 2000s. In addition, the most installed solar cooling system in the Middle East and North Africa region is utilizing absorption cycles.
Variation Simulation of Dissimilar Materials Using Clip Fasteners
Authors: Wärmefjord Kristina , Söderberg Rikard , Lindkvist Lars 
Published: February 2017

The use, and the joining process, of dissimilar materials have recently been highlighted. Joining of dissimilar materials can however be problematic, due to different material properties. Different materials respond differently to temperature changes and this might lead to deformations and stress in the final assembly. The joining methods differ also often from the one used to join similar material.
Variation simulation is used to predict the geometrical variation of a subassembly or a final product. In variation simulation of dissimilar materials it is important to include material properties in order to achieve an accurate result. Also the effects form joining method must be included in the simulation. To join dissimilar materials like plastic and sheet metal parts, clip fasteners are often used.
This paper presents a method for variation simulation of dissimilar materials with a focus on how to model clip fasteners. The method allows effects of temperature changes on holding forces and geometrical variation in the final assembly to be evaluated. Holding force refers to the force a clip fastener must withstand after the parts are joined. The method proposed can be used to support the design and selection of clip fasteners.
MATLAB Simulation of Autonomous Servo Driven Oil-Hydraulic Power Unit
Authors: Seabra Eurico , Costa Jorge , Puga Hélder , Leão Celina 
Published: February 2017

Servo driven hydraulic power units have been implemented in some sectors of industry in order to counteract rising energy costs and reduce our ecological footprint. The advantages associated with the use of these technologies has motivated us to research a new control approach that allows its use independently, with reduced implementation costs and high efficiency.
This investigation develops new solutions to concurrently implement and improve volumetric control methodology for oil-hydraulic power units, which aims to produce and provide strictly necessary hydraulic power to the actuators. The approach used is based on a balance of flows present in a hydraulic circuit, reducing the pressure ripple generated by the pumps, valves and actuators, using a hydraulic accumulator.
The work begins with the mathematical modeling of a volumetric oil-hydraulic power unit, designed to demonstrate the concepts of the project, its components and the associated advantages. The definitions of the models presented are intended to exemplify the new control strategy and infer about the possibilities that arise from the use of this new methodology for power oil-hydraulic units.
In order to carry out the research and conclude about the results of the simulations, two simulations were performed using MATLAB Simulink software for two distinct hydraulic circuits and their control strategy: resistive control and volume control with the use of a servo motor.
In the resistive control, an internal gear pump driven by an induction motor with constant speed uses a pressure regulating valve to derive the excess of the flow to the reservoir. Despite their low efficiency, this type of assembly has very low costs and has a very good dynamic compared with traditional volumetric drive systems, avoiding the use of dedicated engineering.
The volumetric control makes use of an internal gear pump (to allow direct comparisons with the resistive control method), a servo motor, a hydraulic accumulator and a directional valve which prevent the flow from de accumulator draining into the reservoir during the downtimes. The controller allows you to establish a direct relationship between the accumulator volume and pressure of the hydraulic circuit.
The control methodology discussed throughout this work reveals an alternative volumetric control solution to consider, whether in new equipment or in retrofitting even with the different objectives of existing technologies available in the market.
The simulations allow us to conclude on energy-saving and environmental advantages of the volumetric control system presented, comparing it with existing systems on the market.
Strength and Hardness Assessment of Copper and Copper Alloy Coatings on Stainless Steel Substrates
Authors: Ibrahim Mohamed , Al-Athel Khaled , Arif Abul Fazal M. 
Published: February 2017

Coatings are extensively used in many areas including industrial and medical fields to serve various functions as corrosion resistance, wear resistance and antibacterial purposes. Copper and copper alloys are among the most widely applied coating materials for several industrial and medical applications. One of their widely used copper coating applications is in the antibacterial coating area. Most of the research done in this field focuses on the antibacterial behavior with no comprehensive assessment regarding their mechanical properties, such as hardness and adhesion strength. In this work, mechanical assessment of strength and hardness of pure copper and several copper alloys including Cu Sn5% P0.6%, Cu Ni18 Zn14 (German silver), and Cu Al9 Fe1 are studied experimentally and numerically. All coatings are deposited on stainless steel substrate disks of 25mm diameter by wire-arc thermal spraying at the center of advanced coating technologies, University of Toronto. All coatings are 150 microns in thickness, with two additional thicknesses up to 350 microns for Cu Ni18 Zn14 (German silver) and Cu Al9 Fe1. The effect of the coating thickness and composition on the mechanical properties is studied for all the copper and copper alloy samples with the varying thicknesses between 150 and 350 microns.
Scanning Electron Microscope (SEM) is used to study the surface as well as the cross-sectional microstructure of the coatings. Vickers micro-indentation tests are used to evaluate hardness at various locations on the cross-section of the coating and the substrate. This is used to evaluate the effect of the deposition of the coating material, and the subsequent solidification, on the hardness of the coating layer as well as the substrate near the coating interface. Pull-off adhesion tests are performed to evaluate the effect of the coating composition and thickness on the strength of the coatings. Tests are carried out to compute the pull-off failure stress that causes the delamination between the coating and the substrate. Computational analysis will be used to calibrate the experimental data when available by means of finite element analysis.
The preliminary pull-off tests show interesting results as the samples with lower coating thicknesses exhibit delamination at higher strengths. This is due to the increase in residual stresses in higher thicknesses building up during the deposition process. Some of the samples did not even fail at lower thicknesses of 150 microns. A comprehensive analysis between the adhesion strength and hardness will be very useful in understanding the effect of coating composition and thickness on the mechanical properties of the coating.
Deformation and Failure Mechanisms of Austenitic Piping Under the Influence of Oxyhydrogen Reactions
Authors: Offermanns Stefan , Weihe Stefan 
Published: February 2017

The present paper deals with the deformation and failure mechanisms of austenitic piping under the influence of oxyhydrogen reactions for the safety evaluation of incident scenarios in technical installations based on previous work of the author [1–5].
For the characterization of the processes, detonation tests performed at the Materials Testing Institute University of Stuttgart (MPA Stuttgart) have been used. The aim of these experiments was to study the detonation processes in head spray cooling piping of boiling water reactors. The experiments were performed on austenitic pipes with an outer diameter of O. D. = 114.3 mm and various wall thicknesses. Oxyhydrogen was used in its stoichiometric ratio of 2H2+O2 mixed with various amounts of an inert gas component. These tests have shown that less amounts of reactive gas may result in a stronger reaction of the pipe structure. This observation is attributed to the influence of the so-called overdriven detonation.
Depending on the ratio of oxyhydrogen to the inert gas component and the pipe-wall thickness, adiabatic shear bands can occur in the piping structure. Adiabatic shear bands are very narrow zones with intense localized shear deformations due to the conversion of a significant portion of strain energy into heat.
In order to describe this phenomenon numerically, a strain-based failure model was used which can reflect material damage over a wide range of different stress states. However, it has shown that damage of the studied material depends significantly on the Lode angle. Furthermore, no clear dependence of the failure limit on the loading rate has been found for the studied material.
For the constitutive description of the material behavior under the occurring loading rates and temperatures suitable material models were selected and the required parameters have been evaluated experimentally and verified by numerical methods. With the aid of this constitutive description of the material behavior and the failure model numerical simulations of the detonation tests were carried out.