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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
171

Optimization of Wire Diameter for Maximizing Removal Rate in Wire Electrical Discharge Machining

Biman-Telang, Akshyn January 2023 (has links)
Wire electrical discharge machining (WEDM) is a precision machining process that uses electrical discharges struck between an axially moving wire electrode and the workpiece to remove material through melting and vaporization. WEDM is replacing traditional processes like broaching for machining safety-critical components such as the turbine disk in the manufacture of fuel-efficient jet engines. The main issue preventing the more widespread use of WEDM is that due to WEDM being less productive than broaching, it currently requires 6 WEDM machine tools to replace a single broaching machine to maintain the same throughput. The main factor limiting WEDM productivity is wire breakage. To increase the Cutting Rate (CR) more power is required, and increasing power also increases the likelihood of breakage. The goal of this research is to determine whether wires thicker than the conventional 0.25 mm diameter will both optimize the cutting rate and minimize breakage. Thicker wires will allow for an increase in the duty factor, with a significantly decreased incidence of wire breakage. Given that an increased wire diameter also increases the kerf width, this research seeks to identify the optimal wire diameter that maximizes the linear cutting rate. This research concluded that using wire of optimal diameter in WEDM increases the CR by as much as 400%. / Thesis / Master of Science in Mechanical Engineering (MSME) / In order to secure jet engine blades onto the engine, complex features called Firtree Root Forms (FTRF) are used. These features need to be very precisely cut in order for the engine to work at peak efficiency. Currently, industry is using a manufacturing process called broaching to machine these FTRFs, however broaches wear out over time, which causes imprecise cuts. The solution to this is to use Wire Electrical Discharge Machining (WEDM). The problem with WEDM is that it takes on average 6 machines to replace a single broaching machine in terms of productivity. The objective of this project is to increase the cutting speed (and thus productivity) of WEDM, and one of the ways to do that is to increase the electrode wire diameter. This allows for more power to be used in the machining process without the risk of wire breakage, which is a major problem when cutting with WEDM. The research presented in this thesis successfully demonstrates that using thicker wires in WEDM can cut as much as 400% faster than the wires currently in common use in industry.
172

Copper Wire-Bonding Reliability: Mechanism and Prevention of Galvanic Aluminum Bond Pad Corrosion in Acidic Chloride Environments

Asokan, Muthappan 05 1900 (has links)
With the reliability requirements of automobile microelectronics pushing towards near 0 ppb levels of failure control, halide induced corrosion issues in wire bonded devices have to be tightly controlled to achieve such a high reliability goal. With real-time corrosion monitoring, for the first time we demonstrated that the explosive H2 evolution coupled with the oxygen reduction reaction, occurring at the critical Al/Cu interfaces, is the key driving force for the observed aggressive corrosion. Several types of passivation coating on Cu wire surfaces to effectively block the cathodic H2 evolution were explored with an aim to disrupt this explosive corrosion cycle. The properties of the protective coating were evaluated using various analytical techniques. The surface coating exhibited high thermal stability up to 260 °C (evaluated using TGA analysis). A uniform, highly hydrophobic coating (surface contact angle of >130° with water), was achieved by carefully controlling CVD parameters such as time of deposition, surface control of Cu metal, amount of inhibitor compound loading, temperature of coating process etc. FTIR spectroscopy combined with corrosion screening was used to optimize the CVD passivated coating with strong chemisorption. SEM and EDX, XPS were carried out on various coated surfaces to understand the composition and selectivity of the film formed through this surface treatment. The surface selective nature of this coating (towards Cu) proved helpful in preventing potential delamination issues during epoxy molding process. The corrosion testing was carried out via HAST testing at 130°C, 2 atm pressure and 100% RH for 48 hours. Delamination analysis and continuity test showed that the inhibitor compound was able to effectively prevent the corrosion even after exposure to harsh HAST conditions.
173

Breakdown Voltage Performances of Aluminum and Copper Conductor Wire Under Compression Stresses

Suchanek, Richard Donald, III 01 April 2016 (has links)
In the global, competitive market of energy transformation, increased operational expenses and depletion of raw materials have resulted in companies pursuing alternate materials to reduce consumer costs. In electrical applications, energy is transformed using materials with high electrical conductive properties. The conductive material used to transmit a signal is called conductor wire and is comprised of any material that has the ability to move charged particles from one point to another without propagation or delay. The conductor wire in many applications is encapsulated in epoxy resin called enamel. The enamel is the insulation system that provides necessary dielectric clearances to prevent voltage leakage. The most common form of energy transformation is the electric motor. Both copper and aluminum conductor wire are commonly used in electric motors, but copper is preferred due to thermal and electrical properties. However, there is a significant economic incentive to convert to aluminum conductor wire. Limited white papers are available comparing the performances of the two materials; the research is limited to physical and electrical performances of the raw material and does not take into considering the insulation. The conductor wire, which includes the insulation, is susceptible to damage during the manufacturing process and is an inherent risk if not fully understood. During the blocking process, the conductor wire is pushed and compressed into lamination slots. This process changes the conductor wire outer diameter to accommodate void spaces within the lamination slots. The percentage of slot area occupied by the conductor wire is known as slot fill. The higher the slot fill, the more wire occupying the available space. The higher the slot fill, the more force required to fill the slots. High slot fill motor designs provide a performance advantage with little associated cost. The more wire pressed into the slot, the higher the potential efficiency gains. However, high slot fill motors are more susceptible to damage. The study is designed to evaluate and measure the durability of aluminum and copper conductor wire under simulated compression stresses. Utilizing this information, electric motor manufacturers can push current design limits without affecting conductor wire quality and reliability.
174

Investigation of the circular magnetization curve for nickle-iron wires under torsional and tensile stress

Asch, Arlyn Eugene. January 1962 (has links)
Call number: LD2668 .T4 1962 A82
175

Mekaniska beräkningar av armeringstråd vid förläggning på högspänningskablar / Mechanical calculations of reinforcing wire upon the application on high voltage cables

Nilsson, Philip January 2014 (has links)
This thesis has taken place at ABB High Voltage Cables in Karlskrona and focuses on their reinforcement process (AR50) which reinforces the cable by application of reinforcement wires. The research is strictly limited to only the short period during the application of the wire on the cable and investigates stress differences in one reinforcing wire depending on cable - and wire dimensions as well as brake forces used in the production. The study follows a model - and theory development research process combined with a testing process to obtain the results. The study aims is to increase and expand ABB's knowledge about the reinforcing process that is used to strengthen and protect ABB’s all different high voltage cables together with a computational calculation model. The model is developed in the FEA (Finite Element Analysis) program ABAQUS through a dynamic explicit model. An explanation of how the calculation model has been built and the parameters used are described in this report. These parts then contribute to the outcome of the study which provides a sense that the brake force used in AR50’s reinforcement process does not need to be controlled with a high precision so long as it is large enough to hold the reinforcement wire stretched upon the application. The study also shows that different cable - and wire dimensions does not affect the stress levels somewhat significantly by reinforcing the process and that the nipple used in reinforcement process to press down the reinforcing wire on the cable is the main source that determines how the stress distribution looks like on the reinforcement wire. / Detta examensarbete har tagit plats på ABB High Voltage Cables i Karlskrona och fokuserar på deras armeringsprocess (AR50) som förstärker kabeln genom påläggning av armeringstrådar. Arbetet är starkt begränsat till enbart den korta perioden för själva påläggningen av tråden och undersöker spänningsskillnader i en armeringstråd beroende på olika kabel – och tråddimensioner samt bromskrafter som används i produktionen. Studien följer en modell – och teoriutvecklande forskningsprocess kombinerat med ett utprövande resultatbildande. Studiens syfte är att tillsammans med en beräkningsmodell öka och fördjupa ABBs kunskaper kring armeringstråden som idag används för att stärka och skydda ABBs alla olika högspänningskablar. Beräkningsmodellen tas fram i FEA (Finita Element Analys) prorammet ABAQUS genom en dynamisk explicit modell. En förklaring till hur beräkningsmodellen har byggts upp och vilka parametrar som används beskrivs i rapporten. Dessa delar bidrar sedan till resultatet i studien som ger en bild av att bromskraften som används i AR50s armeringsprocessen inte behöver kontrolleras med en hög precision så länge den är tillräckligt stor för att hålla armeringstråden sträckt vid påläggningen. Studien visar också att olika kabel – och tråddimensioner inte påverkar spänningsnivåerna något markant vid armeringsprocessen och att nippeln som används i armeringsprocesen för att trycka ner armeringstråden mot kabeln bestämmer hur spänningsbilden ser ut. / <p>This thesis is kept confidential</p>
176

Reactor disposal evaluation at Sol Voltaics

Nilsson, Jens, Nilsson, Johan January 2016 (has links)
The purpose of this project was to map the current method for decommissioning / disposing of the Nano-wire reactor at Sol Voltaics. Additionally, alternatives should be suggested based on the findings during the mapping processes and the subsequent analysis. The aim of the presented alternatives was to improve the current workflow for reactor decommissioning based on five identified areas; Rules and Regulations; Environmental aspects; Safety aspects; Economical aspects and Logistical aspects. The existing disposal procedure was divided into six steps. The first step involves a purging procedure to make sure no hazardous gases remain in the reactor. The second step is to dismantle and seal the reactor. The third step is to move the reactor to a loading dock. The fourth step is the transport between Active Biotech in Lund and Sydblästring AB in Malmö. The fifth step is the disassembly and cleaning process of the reactor parts, including waste management. The sixth and final step is to move the cleaned parts to SYSAV in Malmö for final disposal. Finally, Rules and Regulations as well as Safety aspects were identified as having partial improvement potential. Ideas for possible alternatives in these areas was devised and analyzed according to all five areas to make sure that the improvements in one area would not bring undesirable shortcomings in another.
177

Standardize Your IP Traffic with TMOIP

Grebe, Andy 10 1900 (has links)
ITC/USA 2009 Conference Proceedings / The Forty-Fifth Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2009 / Riviera Hotel & Convention Center, Las Vegas, Nevada / With the emergence of higher bandwidth Ethernet networks on ranges, many ranges are converting their data transport from ATM(Asynchronous Transfer Mode) networks to Ethernet networks. Both networks have their respective advantages and disadvantages, however one reoccurring issue is product interoperability. The RCC (Range Commanders Council) TTG (Telecommunications and Timing Group) created the Telemetry over IP (TMoIP 218-07) solution with input from various ranges and vendors to solve this issue. This specification allows ranges to use different vendors together for Telemetry over Ethernet, based on specific needs at each site. This paper targets those who are thinking about converting from ATM to Ethernet networks.
178

Evolving Range and DISA Networks Using Pseudo Wire

Merritt, Joseph 10 1900 (has links)
ITC/USA 2007 Conference Proceedings / The Forty-Third Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2007 / Riviera Hotel & Convention Center, Las Vegas, Nevada / The Eastern and Western Ranges along with DISA share a similar vision around Net-Centricity such that "Anyone, anywhere can get to any data source and exploit the information they are authorized to access." Their legacy infrastructure is built around TDM and ATM transport networks, which are link based and connection oriented. To achieve the vision the infrastructure must evolve towards a packet switched network (PSN) that is meshed based. Consequently, a means to interwork non-IP enabled services is required. Pseudo Wire protocol encapsulation provides the means for extending telemetry, data, voice, and video services in native formats over Ethernet, IP, and MPLS networks in a reliable way that delivers greater operational efficiency and a smooth migration to a single converged network.
179

SELECTIVE POLARIZATION IMAGER FOR CONTRAST ENHANCEMENT IN EXTENDED SCATTERING MEDIA

Miller, Darren Alexis January 2011 (has links)
Improved imaging and detection of objects through turbid obscurants is a vital problem of current interest to both military and civilian entities. Image quality is severely degraded when obscurant fields such as fog, smoke, dust, etc., lie between an object and the light-collecting optics. Conventional intensity imaging through turbid media suffers from rapid loss of image contrast due to light scattering from particles (e.g. in fog) or random variations of refractive index (e.g. in medical imaging). Intensity imaging does not differentiate between rays scattered off particles in the obscurant field and those reflected off objects within the field. Scattering degrades image quality in all spectral bands (UV, visible, and IR), although the amount of degradation is wavelength dependent. This dissertation features the development of innovative system designs and techniques that utilize scattered radiation's deterministic polarization state evolution to greatly enhance the image contrast of stand-off objects within obscurant fields such as smoke, fog, or dust using active polarized illumination in the visible. The produced sensors acquire and process image data in real time using computationally non-intensive algorithms that differentiate between radiation that scatters or reflects from obscured objects and the radiation from the scattering media, improving image contrast by factors of ten or greater for dense water vapor obscurants.
180

Development of a laser-wire beam profile monitor for PETRA-III and CLIC

Aumeyr, Thomas January 2013 (has links)
The Compact Linear Collider (CUC) is a proposed electron-positron collider with a centre- of-mass energy of 0.5 to 5 TeV, optimised for a nominal centre-of-mass energy of 3 TeV, at high luminosities exceeding 1034 cm-2s-J. The high beam charges in the CUC beams make classical techniques for measuring the transverse beam size such as optical transition radiation (OTR) screens or wire scanners very difficult, which necessitates the use of non-invasive beam- size monitors. The laser-wire is a system that meets these requirements; it uses inverse Compton scattering to determine transverse beam-sizes by scanning a laser beam across the electron beam. This thesis describes how such a laser-wire system was installed and operated at PETRA-III at DESY, which uses an automated mirror to scan a Q-switched laser pulse across the electron beam and is developed from the system previously operated at PETRA-II. The measurements of key performance parameters are described and used in determining the emittance of the PETRA-III beam. The thesis includes a detailed investigation of the laser .' system as well as the collision measurements. Furthermore, simulations were carried out to design a similar system for the proposed transfer line of the CUC Drive-Beam and the necessary baseline characteristics of such a system are described.

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