A method is described whereby the recovery of plasmas formed by the passage of a high current discharge across a spark gap has been measured as a function of both the time after the passage of a current pulse and the radial distance from the centre of the spark gap. The effects of pressure, current magnitude and current waveform on the recovery time of the test gap were investigated and it was found that all of them exerted powerful but explicable influences on the recovery. Gas temperatures were derived using the assumption that the Paschen Law holds true during the final recovery period. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Call number: LD2668 .T4 1960 H84

Thesis (M.Sc.) --University of Adelaide, 1951. / Typewritten copy.

In the last few decades India has advanced socioeconomically due to the rapid growth of industries and automobile sector. This in turn increases the use of fossil fuel and diesel. The atmosphere gets polluted due to the harmful substances, which comes from the burning of fuel. These pollutants can be in the form of gaseous, liquid or solid particulate. Air pollution, both indoor and outdoor, is a significant cause of health problems worldwide. In the automobile sector diesel engine exhaust is the major contributor for the air pollution amounting to about 60%. Exhaust generally contains oxides of Carbon, Nitrogen, Sulfur, Soot, Oil mist etc. Due to the heavy consumption of diesel as a fuel there is an urgent need to control diesel exhaust. Successful control of emissions from combustion engines particularly from diesel engines is yet to be achieved. The conventional techniques which are available to control emission now are either difficult to operate or does not satisfy the stringent emission standards. Among the major pollutants of diesel exhaust NOx is one of the pollutants to be taken care of as it is the major contributor for acid rain, photochemical smog etc. Further the NOx cause health problems leading to respiratory diseases, pneumonia, asthma etc. Till date, despite improvement in aftertreatment technologies, diesel engine continues to emit large amounts of NOx. The failure of conventional techniques lead to the development of non-conventional techniques such as high voltage electric discharge based plasma which has already been proved to be economical and highly efficient in Industrial Electrostatic Precipitators. Till now all the research regarding control of NOx has been done at the laboratory level using conventional DC and rotary spark gap based high voltage power supply. However, this is not a feasible option for Automobiles. The objective of this thesis is, therefore, to design and fabricate a solar powered high voltage power supply to be retrofitted into a vehicle. This leads to the development of power supply which will be of smaller size & capable of supplying high voltage to the gas treatment reactor. In the present work emphasis has been made on the design and development of a DC/HVAC power unit based on switch mode power supply approach. The thesis mainly presents the following issues:  Design & fabrication of solar powered high voltage high frequency power supply for the production of Electric Discharge Plasma.  Actual diesel exhausts treatment with the Electric Discharge Plasma.  Exhaust treatment with conventional 3 way CAT.  Exhaust treatment with cascaded plasma & catalyst/adsorbent system  Comparative analysis. The high voltage power supply gives an output of 16kV peak to peak at 12.2 kHz with a 50W power rating. This high frequency high voltage is applied to the gas treatment reactor and studies on actual diesel exhaust cleaning were carried out. It was observed that there was substantial improvement in the NOx removal under this high frequency AC application when compared to conventional 3-way catalytic converter. Studies have also been carried out at different engine loads and a comparative analysis has been made by cascading the NTP with adsorbents & catalysts and results as discussed in detail.

Sanborn C. Brown. / "April 12, 1951." / Bibliography: p. 15. / Army Signal Corps Contract No. W36-039-sc-32037 Project No. 102B. Dept. of the Army Project No. 3-99-10-022.

Endodontics is a branch of dentistry focused on preventing and treating dental conditions affecting the pulp, root canal system, and periapical tissues Exposure to bacteria can cause infection of the root canal system and surrounding tissues. Endodontic treatment can be highly challenging due to the bacterial biofilm and anatomical complexities. Therefore, the development of new technologies that effectively disinfect root canals is imperative for the improved success of endodontic treatment. EndoLogic device is a new irrigation technology works by creating an electrical discharge in a conductive liquid that can kill pathogens. The electric discharge causes cavitation, shock waves, ultraviolet radiation, multiple anti-microbial radicals. The findings for the EndoLogic device were inconsistent. Preliminary LIVE/DEAD staining indicated promising results, but later CFU experiments showed a negative correlation between EndoLogic activation and root canal disinfection. Additional experiments are planned to further investigate the effectiveness of this innovative device. / 2026-08-02T00:00:00Z

The aim of this master's thesis is experimental electric discharge sinking of special materials for the aerospace industry. The first part is a general overview regarding the technology of electric discharge machining with emphasis on electric discharge sinking. Following this is a practical part devoted to the electric discharge sinking of the Nimonic 263 material with a copper tool electrode with a subsequent evaluation of surface and subsurface changes in this material. The wear of the tool electrode is also examined with the conclusion highlighting combination of machined material and tool electrode material behave in different working conditions and how the surface layer of machined material is affected.

Electric Discharge Machining (EDM) is a machining method suitable for repair and maintenance operations in nuclear power plants. Crack removal and material sampling are two common operations where EDM is used in the nuclear power industry. Each crack removal or material sampling operation is unique, a new EDM-tool is therefore designed for every operation. This, together with the fact that the electrode used in the EDM-tool usually wears out before the crack is removed or the sample has been collected, is the foundation of this thesis. The objective was to develop one or several concepts of a modular EDM-tool with the ability to change electrode at repair location. This to shorten the development time for EDM-tools and the time for electrode change during an EDM operation. The concepts would be developed to the extent that a prototype could be manufactured and tested. The result is in accordance to the objective with one fully developed concept ready for manufacturing. It has not yet been manufactured, and therefore not been tested. There are still some sections of the tool that needs to be verified, for example the electric supply to the electrode. The concept consists of; a slim EDM-tool with the ability to lock the rotating electrode shaft, compact dielectric fluid- and electric-supply, hydraulic actuator with belt drive and an electrode magazine with place for 3 electrodes. Keywords: Nuclear, EDM, Electric Discharge Machining, Product development, Crack removal / Electric Discharge Machining (EDM) är en avverkningsmetod lämplig för reparations- och underhållsarbete i kärnkraftverk. Sprickbortagning och materialprovtagning är två vanliga operationer som utförs med hjälp av EDM inom kärnkraftsindustrin. Varje sprickbortagningsoch materialprovtagnings operation är unik, därför utvecklas ett nytt EDM-verktyg inför varje operation. Detta tillsammans med det faktum att elektroden som används i EDM-verktyget ofta slits ned innan sprickan har avverkats eller provet har tagits ligger till grund för detta examensarbete. Målet var att utveckla ett eller flera koncept av modulära EDM-verktyg med möjligheten att byta elektrod på plats där aktuell reparation utförs. Detta för att korta ned utvecklingstiden för nya EDM-verktyg och minska tiden för reparations och underhållsarbeten. Koncepten skulle utvecklas så långt att en prototyp kunde tillverkas och testas. Resultatet är i linje med målet, ett välutvecklat koncept som är redo för tillverkning och testning. Det har än så länge inte blivit tillverkat och således inte testats. Konceptet består av ett smalt EDM-verktyg med möjlighet att låsa elektrodrotationen, kompakt dielektrikum- och ström-tillförsel, hydraulisk aktuator med kuggremsdrift och ett elektrodmagasin med plats för 3 elektroder. Nyckelord: Kärnkraft, EDM, Electric Discharge Machining, Produktutveckling, Sprickborttagning

Electric Discharge Machining (EDM) is a process for eroding and removing material by transient action of electric sparks on electrically conductive materials immersed in a dielectric liquid and separated by a small gap. A spark-eroded surface is a surface with matt appearance and random distribution of overlapping craters. It is mechanically hard and stressed close to ultimate tensile strength of the material and sometimes covered with a network of micro cracks. The violent nature of the process leads a unique structure on the machined surface and generates residual stresses due mainly to the non-homogeneity of heat flow and metallurgical transformations. An extensive experimental study is presented to explore the surface and sub-surface characteristics together with the residual stresses induced by the process. Layer removal method is used to measure the residual stress profile in function of depth beneath. A finite element based model is proposed to determine residual stresses and compared with the experimental results. The residual stress pattern is found to be unchanged with respect to machining parameters. Thus, a unit amplitude shape function representing change in curvature with respect to removal depth is proposed. The proposed form is found as a special form of Gauss Distribution, which is the sum of two Gaussian peaks, with the same amplitude and pulse width but opposite center location that is represented by three constant coefficients. In each case, agreement with the proposed form is established with experimental results. Results have shown that these coefficients have a power functional dependency with respect to released energy.

This thesis deals with technology of electric discharge machining with emphasis on application of the principle of material removal on wire cut electric discharge machine. The main part is concentrated on wire cut electric discharge machining in terms of a small tool making shop. The goal of the thesis is to create a wire cut electric discharge machining workplace in the company with a focus on the production of cutting tools. The thesis defines requirements for each component of cutting tools and strategies for their machining. Machining of model part and subsequent technical - economic evaluation is included in the final part.