92,992 research outputs found
Development of a virtual reality milling machine for knowledge learning and skill training
No full textCurrent methods of training personnel on high cost machine tools involve the use of both classroom and hands on practical training. The practical training required the operation of costly equipment and the trainee has to be under close personnel supervision. The main aim of this project is to reduce the amount of practical training and its inherent cost, time, danger, personal injury risk and material requirements by utilising a virtual reality technology.
In this study, an investigation into the use of Virtual reality for training operators and students to use the Milling Machine was carried out. The investigation has been divided into two sections: first the development of Milling Machine in the 3D virtual environment, where the real machine was re-constructed in the virtual space.
This has been carried out by creating objects and assembling them together. The complete Milling machine was then properly modelled and rendered so it could be viewed from all viewpoints.
The second section was to add motion to the virtual world. The machine was made of functions as for the real machine. This was achieved by attaching Superscape Control Language (SCL) to the objects. The developed Milling machine allows the users to choose the material, speed and feed rate. Upon activation, the virtual machine will be simulated to carry out the machining process and instantaneous data on the machined part can be generated.
The results were satisfactory, the Milling Machine was modelled successfully and the machine was able to perform according to task set. Using the developed Virtual Model, the ability for training students and operators to use the Milling Machine has been achieved
The Possibilities of Community Redevelopment with Islamic Finance
No full textDue to copyright restrictions and/or publisher's policy full text access from Treasures at UT Dallas is not available. UTD affiliates may be able to acquire a copy through Interlibrary Loan by using the link to UTD ILL.Purpose: The purpose of this paper is to explore the application of a profit and loss sharing approach to tax increment financing (TIF) districts in the USA. Design/methodology/approach: A survey based on this approach was distributed to representatives of community redevelopment authorities (CRAs) in the State of Florida to ascertain practitioner feedback. Findings: Although a majority of the respondents did not feel it was possible for political, economic and legal reasons, some did feel that it was a practical, reasonable and sustainable approach to financing projects for economic development. Some responses were correlated, with others indicating that certain beliefs framed their answers to the questions. Research limitations/implications: The surveys were only distributed to CRAs in the State of Florida. Future research will need to include other CRAs in other states to make the findings more generalizable. In addition, the results are merely descriptive and are not an assessment of a successful application. Practical implications: The need for more development in blighted areas of many cities across the USA will put emphasis on innovative approaches in financing this. The growth of Islamic finance in the USA and the regulatory framework for it might open a doorway for its application in this area. Originality/value: This is the first attempt to apply an Islamic financing methodology to local economic development in the USA, with practitioner feedback. ©2019, Emerald Publishing Limited.Naveen Jindal School of Managemen
Experimental and finite element study of the hydroforming bi-layered tubular components
No full textThe application of finite element method (FEM) in the area of metal forming and material processing has been increasing rapidly during the recent years. The present study has been carried out on one of the unconventional metal forming processes called hydroforming of a multi-layered tube. The study involved both experimental and simulation work using FEA. Multi-layered tubes have extensive advantages in both domestic and industrial uses. The specimen tube consists of two different layers of materials. The outer tube material is brass and the inner tube material is copper. This project is mainly dedicated to the modelling, simulation and advanced study of one of the unconventional metal forming processes called hydroforming in which extremely high fluid pressure is used to deform the metal into desired shape. Various types of complex industrial products can be made by hydroforming. This process is suitable to produce seamless, lightweight, near net shaped industrial components. There are some complex products, which are easier to produce by hydroforming than by conventional technique.
In this research work the main forming load is hydrostatic pressure applied to the internal surface of the tube, together with an in-plane compressive load applied simultaneously. The blank is placed in a pre-shaped die block and due to the action of simultaneous internal pressure and axial load; it is formed into a complex desired shape. If the internal pressure is too high during the process without sufficient axial load it may cause the tube to burst, on the other hand too large axial load without applying sufficient internal pressure may cause wrinkling of the tube. For these reasons, a number of simulations of the hydroforming process have been carried out for different axial load and internal pressure combinations and optimum conditions have been established for the particular process. This simulated hydroforming of composite material tube and the formed product has been analysed on the basis of forming conditions and the simulated forming conditions have been verified by experiment. The simulations of hydroforming process for X or T branch have been carried by using the commercial finite element package ANSYS
Development of a hybrid genetic algorithm based decision support system for vehicle routing and scheduling in supply chain logistics managment
No full textVehicle Routing and Scheduling (VRS) constitute an important part of logistics management. Given the fact that the worldwide cost on physical distribution is evermore increasing, the global competition and the complex nature of logistics problems, one area, which determines the efficiency of all others, is the VRS activities. The application of Decision Support Systems (DSS) to assist logistics management with an efficient VRS could be of great benefit. Although the benefits of DSS in VRS are well documented, however in practice many organisations perform these activities manually using combination of skills, intuition and expertise.
A comprehensive review of literature revealed several drawbacks in the existing methods for addressing VRS. The traditional optimisation approaches have very limited applications and these require high computation time. Also, heuristic approaches are capable only to specific variation, a slight difference in the structure of the problem make the algorithm inefficient. Furthermore, metaheuristics methods require higher computation time and they are context dependent. Also, further investigations on the VRS problem formulations suggest that heuristic approaches usually address a single objective of distance minimisation. However in the real world there may be a number of conflicting objectives. In general, there is a lack of considerations for route selections, resource utilisation, unhlfilled demands, underused capacities, reliability of deliveries, fleet size, human fitness and operational cost. Also, these approaches fail to realise non-linearity within objectives and constraints defined for VRS problems. Furthermore, there are no clear distinctions between hard and soft constraints considered in these methods. Finally, the existing approaches fail to capture stochastic and dynamic nature of the logistics processes.
In order to overcome the above-mentioned drawbacks, this study designed and developed a hybrid DSS to assist logistics managers with VRS tasks. The capabilities of the developed DSS have then been applied to a Liquefied Petroleum Gas (LPG) distribution company. The architecture of this DSS is composed of Genetic Algorithm (GA) optimisation tool and a simulation model. The GA module aims to provide a pool of near optimum transportation schedules. The simulation module is used to further evaluate the generated schedules. The feed back from the simulation module is used to update the GA for reoptimisation. Some unique features of this DSS are such as: development of a multi modal genetic algorithm to address VRS problems; considering supply chain performance measures as part of VRS problem formulation; allowing consideration of different objectives, soft or hard constraints concerning the supply chain, considering linearlnonlinear relationships within objectives and constraints defined and finally, considering stochastic and dynamic behaviours of the supply chain system.
The GA and simulation tool integration provides unique benefits that have not been in the literature such as consideration of practical requirements, uncertainties, dynamic and stochastic behaviours, considering several criteria and producing different alternative solutions. Also, this integration allows the GA model to filter out solutions that are less competitive and therefore reducing the simulation time evaluation, which is computationally expensive. Furthermore, the human interaction with the system assists in generating higher quality of solutions. Finally, the clear benefit of this DSS is the fact that it greatly influences the applicability of the GA generated schedules and provides better confidence in implementation of these solution
Investigation into coatings produced from nanoparticle blended feedstock for rotating equipment repair applications
No full textCoating of carbon steel with conventional and nano particle blended feedstock material is considered in relation to repair applications of rotating equipment. Gas Metal Arc Welding (GMAW) and Wire Arc Spray (WAS) processes are used to produce the coatings on carbon steel workpieces. The wire arc sprayed workpieces are heat treated at temperature similar to the operating temperature of hot-path components of power gas turbines. The microstructure and metallurgy of the workpieces are examined using the Scanning Electron Microscope (SEM), Optical Microscope, Energy Dispersive Spectroscopy (EDS), X-ray Diffraction (XRD). The indentation tests are carried out to assess the microhardness variation across the coatings. In the case of coatings produced by GMAW, it is found that fine structures are formed in the coating due to the presence of nano particles and they resulted in increased microhardness of the coatings. In the case of the wire arc sprayed workpieces, the formation of dimples like structure at the surface increases the surface roughness of the coatings. In addition, the microhardness of the resulting coating is significantly higher than that of the base material. The heat treatment does not alter the microstructure and microhardness of the coatings significantly
Surface engineering through low temperature deposition of wear resistant layers by reactive magnetron sputter ion plating
No full textThe aim of this investigation was the deposition of hard» wear resistant titanium nitride (TiN) thin films, produced from a reactive magnetron sputter ion plating device, at high deposition rates and low substrate temperatures. An allied objective vas the understanding and development of experimental methods which would permit the deposition of titanium nitride-type layers on plastic. The early part of the work deals with the formation of TiN layers on high speed steel, at 500°C deposition temperature Modifications in equipment design and deposition procedures aided the formation of adherent TiN layers. The routine deposition of stoichiometric titanium nitride vas facilitated by a control feedback network The use of graded interfaces between the film and the substrate improved adhesion. Total gas pressure and the level of substrate bias affect film hardness and wear resistance.
The next stage of the development process vas the deposition of TiN at approximately 250°C substrate temperature. The main source of substrate heating, in the case of an indirectly cooled magnetron, was identified as the heat liberated from the target. The use of a directly cooled magnetron configuration resulted in lover substrate temperatures. With this device, TiN films vere formed on high speed steel at high deposition rates and with good adhesion. The increased ion current to the substrate is, tentatively, attributed to an extended plasma region associated with the directly cooled configuration
Metastable T^N phases are formed from the combination of high deposition rates, low substrate temperatures (250°C) and increased ion bombardment to the substrate. These TiN films, however, are softer and less wear resistant than those produced at 500°C.
The final part of the investigation centred around the deposition of TiN type layers onto plastic T1 -T1 N and AI-T1 -T1N layered structures were deposited onto polycarbonate plastic at 100°C. An experimental design approach was employed to develop adhering coatings. A slight partial pressure of oxygen during the initial Ti deposition improves film adhesion. The use of the aluminium interface improves film reflectivity, cosmetic appearance and adhesion. This aluminium interface makes the multilayer structure more susceptible to physical and chemical attack. The wear resistance of the coated plastic is 2 to 4 times greater than the base plastic material
Measuring industry-science links through inventor-author relations: A profiling method
No full textIn this pilot study we examine the performance of text-based profiling in recovering a set of validated inventor-author links. In a first step we match patents and publications solely based on their similarity in content. Next, we compare inventor and author names on the highest ranked matches for the occurrence of name matches. Finally, we compare these candidate matches with the names listed in a validated set of inventor-author names. Our text-based profile methodology performs significantly better than a random matching of patents and publications, suggesting that text-based profiling is a valuable complementary tool to the name searches used in previous studies.innovation; industry-science links; text-based profiling;
Nonhelical inverse transfer of a decaying turbulent magnetic field
No full textIn the presence of magnetic helicity, inverse transfer from small to large scales is well known in magnetohydrodynamic (MHD) turbulence and has applications in astrophysics, cosmology, and fusion plasmas. Using high resolution direct numerical simulations of magnetically dominated self-similarly decaying MHD turbulence, we report a similar inverse transfer even in the absence of magnetic helicity. We compute for the first time spectral energy transfer rates to show that this inverse transfer is about half as strong as with helicity, but in both cases the magnetic gain at large scales results from velocity at similar scales interacting with smaller-scale magnetic fields. This suggests that both inverse transfers are a consequence of a universal mechanisms for magnetically dominated turbulence. Possible explanations include inverse cascading of the mean squared vector potential associated with local near two-dimensionality and the shallower k^2 subinertial range spectrum of kinetic energy forcing the magnetic field with a k^4 subinertial range to attain larger-scale coherence. The inertial range shows a clear k^{-2} spectrum and is the first example of fully isotropic magnetically dominated MHD turbulence exhibiting weak turbulence scaling
Settling of finite-size particles in isotropically forced, homogeneous turbulence: interface-resolved simulations
No full textWe have simulated the gravity-induced settling of finite-size particles in a turbulent background flow which is forced in a statistically-stationary fashion. The simulations are accurately resolving the solid-fluid interface with the aid of an immersed boundary technique [1]. The parameters of the simulation are (apart from background turbulence) identical to those of reference [2], where particle clustering was observed at a Galileo number of 178 and a solid volume fraction of 0.005. In the present case, it is found that a relative turbulence intensity of 0.24 leads to the disappearance of the clusters; as a consequence, the increase in average particle settling velocity found in [2] also vanishes. [1] M. Uhlmann. An immersed boundary method with direct forcing for the simulation of particulate flows. J. Comput. Phys., 209(2):448–476, 2005. [2] M. Uhlmann and T. Doychev. Sedimentation of a dilute suspension of rigid spheres at intermediate Galileo numbers: the effect of clustering upon the particle motion. J. Fluid Mech., 752:310–348, 2014
Mechanical and metallurgical properties of two-layered diamalloy 4010 and 2002 HVOF coating
No full textDiamalloy 4010, which is iron/molybdenum blend, is resistive to wear and Diamalloy 2002 is resistive to corrosion and wear. However, combination of these powders in layered structure, may offer advantages over the individual powders. In this case, mechanical properties of the resulting layered structure could be improved. Consequently, investigation into mechanical and metallurgical properties of the resulting structure is necessary. High Velocity Oxy-Fuel coating of Diamalloy 2002 [(WC12Co)50,Ni33Cr9Fe3.5Si2B2C0.5] powders and Diamalloy 4010 [Fe68Mo30Cr1.8Mn0.2] powders as well as two-layered coatings consisting of these powders was carried out. In the two-layered structure, Diamalloy 4010 was sprayed at the substrate surface while Diamalloy 2002 was sprayed on the top of Diamalloy 4010 coating. The coating microstructure and morphology were examined using optical microscope, Scanning Electron Microscope (SEM) and Energy Dispersive Spectroscopy (EDS). The indentation tests were carried out to evaluate the microhardness and surface elastic modulus of the resulting coatings. The mechanical properties of the coatings were examined through tensile and three-point bending tests. It was found that the coating produced for Diamalloy 2002 resulted in higher hardness than that corresponding to Diamalloy 4010. The failure mechanism of coating during tensile and three-point bending tests was mainly crack formation and propagation in the coating. The elastic modulus of coating produced from Diamalloy 2002 was higher than that of Diamalloy 4010 coating, which was due to the presence of 12% WC in the coating. The irregularities observed in the elastic limit of the curves indicated the formation of cracks in the coatings, which was particularly true for two layered coating. The shear stress developed at interface of the two-layered coating was responsible for the crack initiation in the coating. The deep cracks were also formed in the coatings after the tensile tests. This was attributed to the local stress centers, which increased the stress intensity under the tensile load
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