Dissertations / Theses on the topic 'Arson investigation'

This study investigated the antecedents and psychological processes inherent in firesetting within an adult intellectually disabled population. A qualitative methodology, grounded theory (GT) was employed to explore the experience of firesetting through verbal self-report. A sample of eight males with mild intellectual disabilities under the care of forensic learning disability services participated in interviews which ranged from 27 minutes 14 seconds to 1 hour 21 minutes 22 seconds. The data produced a preliminary GT which identified eight conceptual categories: Managing internal affect states, the experience of adversity, unsafe others, engagement in multiple offending behaviours, voice entitlement, experiences of fire, and mediators of risk and the function of firesetting. These conceptual categories were linked by an overarching core category of ‘powerlessness’ which was evident in several areas of the participants’ lives and experiences of firesetting. It was concluded that this sense of powerlessness along with the conceptual categories should be considered when risk assessing, delivering firesetting specific treatment and psychological interventions. The clinical implications are discussed and suggestions are made for replication of the current study with larger, more diverse samples and future directions for further research are proposed.

One of the lowest prosecuted crimes in western civilisation is arson. Defence ‘experts’ may be able to discredit a prosecution charge by demonstrating that there are alternative causes for the fire that their defendant was being accused of setting, which were not investigated thoroughly, nor disproved. Unlike many other crimes, a fire may not be detected as arson until the final stages of an investigation, whereas with most other crimes, there is an obvious victim of a crime in the early stages of an investigation. The investigation of fires can be extremely complex. Fire investigators need to ensure that they have conducted their investigation using a systematic and rigorous methodology so that their findings can with-stand any challenges. At the beginning of this project, it was identified that there was a fundamental lack of a systematic methodology to investigate the cause of fires and a need for one to be developed. To address this need, a series of 23 Fire Investigation Road Maps (FIRMs) have been designed, developed and tested at real fire scenes and also during cold case fire investigation reviews to assist a competent fire investigator conduct a thorough, rigorous and systematic investigation to determine the origin and cause of a fire. It is the cause of the fire, that being the ignition source, first combustible material to become ignited and the mechanism that brought the two together which will determine whether the fire was started accidentally or deliberately. The FIRMs are based on the application of the Scientific Method and are divided into groups and categories to ensure a rigorous and thorough process is carried out during an investigation. Some examples of applications of the FIRMs during fire investigations when working with the police, forensic scientists and insurance investigators are the Bethnal Green Road two fire fighter fatalities; ‘Operation Refit’, reviewing the murder of Wayne Trotter; the Iron Mountain data storage depot in East London and the fire in the high rise flats, Lakanal, where six occupants lost their lives. The outcomes of these examples, and many other fire investigations, when applying the FIRMs have demonstrated to the relevant authorities, including several Coroners, that a complete and accurate fire investigation has been conducted. Utilising the FIRMs during a fire investigation will benefit society by enabling existing data to be gathered, documented, analysed and made available for many interested parties, such as Coroners, civil and criminal prosecutors or used to identify any fire safety issues which need addressing. The accurate identification of the cause of a fire, with supporting forensic evidence, will assist the courts in making decisions as to whether the fire was accidental, deliberate or the result of a design or system failure. In the circumstances of deliberate fires, the FIRMs will support any subsequent prosecutions and help increase the low arson prosecution rates that currently exist.

Cette thèse de création dont le maître objet est un moyen métrage – I Can Swim Home (I C S H) – s’inscrit dans le contexte du renouvellement des formes et des pratiques plastiques, dans un contexte où le climat général est en crise (environnement, sanitaire, économie, politique, institutionnel). Quels potentiels de l’art permettent-ils toutefois d’envisager un horizon commun ? Comment l’art et la recherche se proposent t-ils d’expérimenter et d’inventer des outils, des formes partageables, des alternatives concrètes pour renouveler nos modes d’échange, de partage, d’attention, d’adresse et d’imaginaire ? L’angle adopté dans ce doctorat ne consiste pas à recenser des formes plastiques au travers d’une histoire de l’art, mais à saisir ce qui, dans leur motif, relève du désir de « collectif » de l’artiste, et même du travail du « commun » comme œuvre principale. Il s’agit de revenir à cette vérité première de l’art comme « instauration » d’une communauté ouverte, tant par le concernement écologique de l’artiste que par son inscription dans une éthique du soin (care).De ce fait, le travail artistique oscille bien entre la polarité négative d’une crise de la production/reproduction à l’heure de l’Anthropocène et la polarité positive d’une quête d’identité par la pluralité des inscriptions environnementales et sociales de l’artiste. Quant aux pratiques mobilisées ici, en adéquation avec le parti-pris théorique,I Can Swim Home expérimente les voies de l’enquête sur la « reconnexion » (de l’artiste au milieu de l’art, de l’art au vivant) à partir de deux terrains méditerranéens, la Villa Arson et les Îles de Lérins. I Can Swim Home est une œuvre multiforme, constituée d’un film de fiction, de nombreux moments collectifs d’intensification de l’expérience esthétique, d’un carnet de recherche donnant libre cours aux intuitions et questionnements de l’artiste, et d’une analyse critique sur la pratique artistique mobilisant entités et personnes au bénéfice de l’invention plastique
This creation/thesis revolves around a medium-length film – I Can Swim Home (I Can Swim Home), questioning the renewal of forms and the artist’s practice in a context of global crisis (environmental crises, health crisis, economical, political and institutional crisis.) What leads may art provide toward envisioning a communal horizon? How may art, through research and experimentation, contribute to invent tools and practical alternatives allowing us to renew our modes of exchanging, sharing, attention, and imagining? This research doesnot aim to make an inventory of forms throughout art history, but to underline what, in the patterns encountered therein, might reveal the artist’s desire to invoke the collective, and to invoke commonality as the nature of the work itself. I C S H aims to go back to one of art’s primary truth: the “inauguration” of an open community, relying upon both the ecological concern of the artist and their adhesion to an ethics of care. The work of the artist will therefore oscillate between the negative pole of the crisis of production/reproduction in the era of the Anthropocene, and the positive pole of a quest for an identity through the plurality of their environmental and social inscriptions. In line with this theoretical stance, through the multiplicity of practices it implements, I C S H constitutes an experiment in investigating “reconnection” (between the artist and the art world, between art and the living), situated in two Mediterranean sites, the Villa Arson and the Lerins Islands.I Can Swim Home is a multiform comprehensive work including a fictional film, a number of collective moments of intensification of the aesthetical experience, a research notebook documenting the artist’s intuitions and questioning, and a critical analysis of the artist’s practice, inviting entities and individuals to partake into the aesthetic invention

Dissertation of Chief Fire Officer Dipl.-Ing. M. Sc. Dirk Schneider for achieving the academic degree of Dr.-Ing. of the Faculty of Forestry, Geo and Hydro Sciences of the Technical University of Dresden with the title: “Early Detection of Fires in Areas of Forests and other Vegetation” Fires threaten and destroy extensive forest and vegetation areas every year, endangering people and its settlements, leading to significant pressures on the environment and destroying considerable high value resources. The expenditures in manpower, logistics and finance for safety in general and fire suppression in particular are considerable. To minimize these varied and extensive consequences of fires, early detection is desirable, making an effective firefighting strategy possible. This early detection is particularly of importance in remote, large-scale areas and territories not under observation by the population, especially if they are subject to an increased or high vulnerability. After investigating and considering the causes, that repeatedly lead to forest fires not only in the Federal Republic of Germany but worldwide, the author describes different traditional and modern methods for early detection of fires in areas of forests and other vegetation. Furthermore the author develops a performance item catalog, basing on practical and economic experience, by which not only novel early warning systems can be developed, but the systems and methods described in the present study also are assessed and compared. The comparison of various early warning systems is guided not only by means of technical features, but also from an economic perspective. Financial calculation methods, staff costs and the peculiarities in public administration are particularly noted. The author also shows the different parameters that influence the selection of an appropriate early warning system for the detection of forest and vegetation areas. It becomes clear that it is the scene of the incident with its specific parameters that determines the most useful early warning system.

The dissertation examines topics related to the formation of supercapacitors using plasma technology and their analysis. Plasma spray technology was used to form supercapacitors electrodes. Carbon was deposited on stainless steel surface using the atmospheric pressure argon-acetylene plasma. The deposition of nickel oxide on the surface of carbon electrodes was made using magnetron sputtering method. The influence of acetylene amount to the supercapacitors electrodes and the electrical characteristics of the structure were estimated. The nickel oxide influence to the electrical parameters of supercapacitor carbon electrodes, structure and microrelief was assessed too. The etching of carbon electrodes surface with oxygen plasma was performed and its impact on the capacitors electrical parameters and carbon electrode structure was evaluated. Mathematical modeling was used to theoretically estimate the influence of oxygen plasma to the supercapacitor carbon electrode surface microrelief. The anisotropic growth of carbon surface relief and isotropic surface erosion mechanism was theoretically explained. The impact mechanism of the acetylene content and plasmatron power to the carbon electrode structure and electrical parameters was qualitatively explained. The mechanism for understanding the influence of NiO content on the carbon electrodes to the supercapacitor electrical parameters and electrode structure was proposed.
Disertacijoje nagrinėjama tematika yra susijusi su superkondensatorių formavimu ir jų tyrimais naudojant plazmines technologijas. Superkondensatorių elektrodams formuoti panaudota plazminio purškimo technologija. Anglis ant nerūdijančio plieno paviršiaus užnešta panaudojant atmosferinio slėgio argono-acetileno plazmą. Nikelio oksidui nusodinti ant anglies elektrodų paviršiaus panaudotas magnetroninio garinimo metodas. Įvertinta acetileno kiekio įtaka superkondensatorių elektrinėms charakteristikoms ir elektrodų struktūrai. Tai pat įvertinta nikelio oksido kiekio įtaka superkondensatorių anglies elektrodų elektriniams parametrams, struktūrai bei mikroreljefui. Atliktas anglies elektrodų paviršiaus ėsdinimas deguonies plazma ir įvertintas jo poveikis kondensatorių elektriniams parametrams ir anglies elektrodų struktūrai. Matematiniu modeliavimu teoriškai įvertinta deguonies plazmos įtaka superkondensatorių anglies elektrodų paviršiaus mikroreljefui. Teoriškai pagrįstas anglies dangos reljefo anizotropinis augimas ir izotropinės paviršiaus erozijos mechanizmas. Kokybiškai paaiškintas acetileno kiekio ir plazmotrono galios įtakos mechanizmas anglies elektrodų struktūrai ir elektriniams parametrams. Pasiūlytas mechanizmas, aiškinantis NiO kiekio, esančio ant anglies elektrodų, įtaką superkondensatorių elektriniams parametrams ir elektrodų struktūrai.

This thesis deals with a one and two dimensional numerical modeling of a low-pressure DC glow discharge in argon gas. We develop two-component fluid model which uses the diffusion-drift theory for the gas discharge plasma and consists of continuity equations for electrons and ions, as well as Poisson equation for electric field. Numerical method is based on the control volume technique. Calculations are carried out in MATLAB environment. Computed results are compared with the classic theory of glow discharges and available experimental data.

In this study numerical modelling of a moderate pressure DC glow discharge plasma is car- ried out in 1D and 2D geometry. The governing equations include continuity equations for the plasma species (electrons, positive ions and metastable atoms), the electron energy equation (EEE), Poisson equation for the electric

Spectroscopic investigations have been carried out on hollow cathode discharges adapted from laser technology for use as a spectroscopic light source and the argon inductively coupled plasma (ICP) as an excitation source for nonmetal emission. High and low voltage aluminum and copper hollow cathode discharges were studied as a source of ionic and resonant atomic metal emission. The high voltage versions achieve strongly positive current-voltage behavior through utilization of the obstructed discharge phenomenon. The current-pressure-intensity-voltage relationships for low and high voltage copper hollow cathode discharges were studied with the inert gases He, Ne, Ar, Kr, and Xe. The intensity for copper resonant atomic emission with the fill gases Ar, Kr, and Xe improved relative to neon in the high voltage lamp when compared to the low voltage lamp. Absorption measurements through the cathode bore show the ground state atom density to increase with the atomic weight of the fill gas at any given level of intensity, at the fill gas pressure yielding highest resonant atomic copper emission. The estimated ion/atom intensity ratio is increased with fill gases which have metastable or ionization energies greater than the excitation energy of the ion transition. A copper hollow cathode lamp incorporating a short positive column discharge in front of the cathode opening was investigated for its lineshape as measured spectroscopically and by its atomic absorption sensitivity. Incorporation of this positive column allowed higher intensities to be obtained at the same line quality as a commercial hollow cathode lamp. An enlarged cathode volume also improves the lineshape at a given intensity. Inductively coupled plasma spectra for the elements C, O, N, Cl, P, S, and Br were obtained in the vacuum ultraviolet utilizing a vacuum polychromator and SWR film. The detection limit for injected O₂ and N₂ detected electronically by the VUV emissions is 1.3 and 0.9 micrograms respectively with this system. A VUV filter photometer was utilized for oxygen and phosphorus analysis. The detection limit for injected oxygen was 1 microgram with this photometer; the detection limit for phosphorus as inorganic phosphate in aqueous solution is 10⁻³ M. The bandpass of the photometer limits its selectivity.

Le sujet de cette thèse est l'étude de la réactivité de métaux de transition avec les ligands CO et H2O en utilisant la technique d’isolation en matrices d’argon à 12 K et la spectroscopie infrarouge à transformée de Fourier. Nous avons étudié la réaction du dimère hétéronucléaire PdTi avec le CO et nous avons pu identifier les molécules PdTi-CO, TiPd-CO, PdTi(CO)2 et PdTi(CO)3. L’irradiation dans le visible permet de convertir la molécule PdTi-CO avec un CO lié au Ti à la molécule TiPd-CO avec un CO lié au Pd. Dans la deuxième partie de cette thèse nous avons étudié la réaction du titane atomique avec deux ligands différents, le CO et H2O. Cette réaction est spontanée et nous avons ainsi caractérisé les molécules HTiOH-CO et HTiOH-(CO)2, essentiellement à l’aide des molécules isotopiques du CO et de H2O.Des calculs ont été effectués avec la théorie de la fonctionnelle de la densité (DFT). La comparaison entre les données théoriques et expérimentales nous a permis de déterminer les paramètres géométriques et électroniques des espèces étudiées
The purpose of this thesis is the study of transition metal atoms reactivity with the CO and H2O ligands using argon matrix isolation at 12 K and the Fourier Transform Infrared Spectroscopy. We have studied the reaction between the heteronuclear PdTi dimer with CO and we have identified the PdTi-CO, TiPd-CO, PdTi(CO)2, and PdTi(CO)3 molecules. Irradiation in the visible leads to the conversion from PdTi-CO with a Ti-CO bond to TiPd-CO with a Pd-CO bond. In the second part of this thesis, we have studied the reaction between the atomic titanium and the CO and H2O ligands. This is a spontaneous reaction and we have characterized the HTiOH-CO and HTiOH-(CO)2 molecules essentially with the help of the isotopic CO and H2O molecules. Calculations have been made with the density functional theory (DFT). The comparison between theoretical and experimental data allowed us to determine the geometric and electronic parameters of the studied species

Thesis of (M.A.)--University of Alberta, 2009.
Title from pdf file main screen (viewed on August 31, 2009). "Fall, 2009." At head of title: University of Alberta. A thesis submitted to the Faculty of Graduates Studies and Research in partial fulfillment of the requirements for the degree of Master of Arts, Department of Sociology, University of Alberta. Includes bibliographical references.

The intention of this study has been to establish the effectiveness and practicality of several preservation techniques to minimise microbial degradation of volatile organic hydrocarbons that constitute arson evidence. Several typical arson samples have been tested: used carpet, wood and foam with and without additions of known hydrocarbon degrading bacteria (Pseudomonas pudia and P. flourescens). Samples were either unburnt or subject to a simulated fire and then all the samples were stored for periods of up to 16 weeks prior to analyses. The hydrocarbons in arson samples were detected by GC-Mass Spectroscopy using six key compounds to monitor degradation: heptane, decanol, methylbenzene, 1,3-dimethylbenzene, 1,2,3-11 trimethylbenzene, and 1,2,3,4-tetramethylbenzene. The numbers of bacteria in samples were also monitored. The techniques used to reduce microbial degradation included removal of oxygen by oxidation of iron or by substitution with nitrogen gas, reducing water availability from the samples using a desiccant and by the addition of activated charcoal bags at the time of sample collection. The effect that storage at both low and high temperatures was also investigated. The accelerant, petroleum distillate, degraded in all test scenarios except storage at -20°C. After 4 weeks of storage at room temperature, the natural microbial populations in both burnt and unburnt carpet samples degraded the accelerant's six marker compounds by 22% and 32% respectively. By 8 weeks both had degraded by over 40%. The degradation was more rapid if bacterial cultures were added with a decrease of 48% in the unburnt samples and by 25% in the burnt samples after 4 weeks. Similar trends were seen with the painted and unpainted wood and furniture foam samples. The removal of oxygen and water was not sufficient to stop microbial growth and there was no decrease in the degradation of hydrocarbons. The use of activated charcoal in comparison greatly reduced degradation with a decrease of hydrocarbons of only 7.5% after 4 weeks in unburnt samples and 5.5% in burnt samples. The activated charcoal had no effect on microbial growth so the effect is most likely due to the volatile organic compounds being adsorbed by the charcoal and inaccessible for microbial degradation. While storage at low temperatures is the best method of storage to maintain sample integrity the use of activated charcoal added at the time of sample collection provides a cheap and practical alternative that is amenable with current practice.

Fire models are routinely used to evaluate life safety aspects of building design projects and are being used more often in fire and arson investigations as well as reconstructions of firefighter line-of-duty deaths and injuries. A fire within a compartment effectively leaves behind a record of fire activity and history (i.e., fire signatures). Fire and arson investigators can utilize these fire signatures in the determination of cause and origin during fire reconstruction exercises. Researchers conducting fire experiments can utilize this record of fire activity to better understand the underlying physics. In all of these applications, the fire heat release rate (HRR), location of a fire, and smoke production are important parameters that govern the evolution of thermal conditions within a fire compartment. These input parameters can be a large source of uncertainty in fire models, especially in scenarios in which experimental data or detailed information on fire behavior are not available. To better understand fire behavior indicators related to soot, the deposition of soot onto surfaces was considered. Improvements to a soot deposition submodel were implemented in a computational fluid dynamics (CFD) fire model. To better understand fire behavior indicators related to fire size, an inverse HRR methodology was developed that calculates a transient HRR in a compartment based on measured temperatures resulting from a fire source. To address issues related to the uncertainty of input parameters, an inversion framework was developed that has applications towards fire scene reconstructions. Rather than using point estimates of input parameters, a statistical inversion framework based on the Bayesian inference approach was used to determine probability distributions of input parameters. These probability distributions contain uncertainty information about the input parameters and can be propagated through fire models to obtain uncertainty information about predicted quantities of interest. The Bayesian inference approach was applied to various fire problems and coupled with zone and CFD fire models to extend the physical capability and accuracy of the inversion framework. Example applications include the estimation of both steady-state and transient fire sizes in a compartment, material properties related to pyrolysis, and the location of a fire in a compartment.
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Buildings damaged by the fires are a highly recurring phenomenon. This is leading to improve prevention procedures and to conduct more efficient investigations. The purpose of this thesis is to present an investigation methodology known as Structural Fire Investigation, which aims at identifying the causes, both pre-existing and latent, that led to a fire incident. Such investigation includes structural and forensic operations ranging from the gathering of initial information to evidence sampling and from document analysis to computational tests. At the base of the investigative methodology, there is the error analysis, the consequent causes, the effects that the fire produces in the scene and the consequences in the structure. It starts from analysis of accidents and then describes the fire event and the methodologies used to investigate which is also suggested by the NFPA 921 Guide for Fire and Explosion Investigations in which the importance of Fire Investigation is described even from the structural point of view. The starting point of this work is the occurrence of historical fire incidents at an international level, such as a fire incident that occurred in the Mont Blanc tunnel or an event occurred in a hotel in Taiwan. This work also addresses fire modelling by the software Fire Dynamics Simulator, in such a way that the hypotheses formulated during the sampling process are tested by the computational structural analysis of the incident. This thesis also aims at providing investigators with an innovative software package for conducting fire investigations, in an effort to produce a Unique Investigative Protocol. This tool will standardize the procedures at the core of the Structural Fire Investigation, so that parameters, other than just the point of origin of the fire are scrutinized. As such, Fire Investigation becomes a self-contained subject under the wider umbrella of structural engineering, and a forensic procedure just as important as those typically undertaken when fire-damaged buildings are involved. Finally the Structural Investigations that are constantly occurring at the core of Reverse Engineering might lead to the establishment of new frontiers, both from a structural optimization and fire reliability standpoint.

Work described in this thesis contains the results of the study on subjecting carpet and foam to different burning tests and the evaluation, by gas chromatography/ mass spectrometry (GC/MS), of the burnt residues for the purpose of identifying compounds which may potentially interfere with the identification of petrol in arson investigation.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1992.
Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 109-110).

碩士
逢甲大學
材料科學與工程學系
104
A high density plasma with a large area has been required from Micro-electromechanical Systems (MEMS) as well as semiconductor industries. The development of the high density plasma of 15 inch in diameter for thin film deposition and etching treatment has partly started. However, most of industries have not decided such a plasma source due to different serious problems. Very High Frequency (VHF) plasma source is one of the highly respected techniques to produce high density plasma, with benefits of high electron density, low electron temperature and simply device structure. However, due to this high frequency (30~300 MHz) empolyed, the concomitant standing wave and skin effect impact the possibility of large area (>1 m2) processing, even the gerometric design of electrode system is very similar to traditional plasma enhanced chemical vapor deposition (PECVD). Followed by references, a VHF plasma simulator device assembly with balanced power feeding system and controllable capacitance was setup in this work to avoid standing wave and skin effects. To study the characterizations of a VHF plasma with Ar source, which has highly ionization rate and widely application, a cylindrical Langmuir probe system was employed. The investigation was focused on plasma properties such including electron density, electron temperature, sheath potential and the uniformity of plasma distribution influenced by the control parameters of Ar pressure and input power, discharge gap. Where in this study, the 60 MHz VHF power source was chosen; the used discharge gap was ranged between 10 ~ 35 mm; the Ar pressure was selected up to 266 Pa; the input power was controled from 50 to 350 W. In the results, the functions of pressure and input power influence on plasma characteristics were estimated. The peak plasma density and electron temperature were both influenced strongly by both the applied power and pressure, which is consisted with electron trapping theory. However, due to the ion collisions effects, plasma density Ni is much more unstable than that of Ne when the pressure is higher than 100 mTorr. The change of gap distance also significantly affected the plasma characteristics. Moreover, axial distributions of the VHF Ar plasma parameters were examined using a movable Langmuir probe. Mentionable, the peak plasma density occurred at the near electrode regions but the center between electrodes under all applied power conditions. This is believed influenced by the charge effect. About the electron temperature, the poit effect caused the unstable behavior when the tip of Langmuir probes close to the plate electrode. The effect of hollow cathode discharge from the porous electrode on the probe is relatively negligible. At the last, the uniformity of plasma density is weaker than originally believed, which required further correction and investigation.

碩士
國立中央大學
機械工程研究所
95
Copper and its compounds such as Cu-W alloy are the most common electrode materials in application of electrical discharge machining (EDM). However, due to its intrinsic modest melting temperature and high coefficient of thermal expansion which result in low working efficiency, it is not suitable for high current (>100Amp) and high material removal rate (MRR) EDM condition. An innovative electrode material was fabricated by adding different amount of Multi-Walled Carbon Nanotube (MWCNT) into copper matrix to enhance its material removal rate and durability in view of carbon nanotube’s remarkable properties such as high thermal conductivity and electrical conductivity. The purpose of this master thesis is to investigate the electrical discharge machining behaviors by this new type of electrode material. In this approach, the nano-size (diameter：20~40 nm; length：5~15 μm) MWCNT with 0.5, 1.0, 3.0 wt % were mixed with copper powder (40~50 μm). After well dispersed by shaking/ball-milling process, the mixture was poured into the graphite die and underwent 16 MPa pressure to hot press for 1050℃and 60 min under 10-2 Torr vacuum condition. The hot-pressed disk-shape Cu/MWCNT composite was then machined into rectangle by mill and WEDM to serve as electrode for investigating the EDM behavior. The effect of EDM parameters such as pulse duration (Ton), discharging current (Ip) and the improvement of material removal rate (MRR) were analyzed. From the experimental results, the highest MRR with Cu/MWCNT electrode was achieved by using 100 μs pulse duration. To compare with electrode wear rate (EWR) between pure copper and Cu/MWCNT electrodes, it was found that all three compositions of Cu/MWCNT electrodes have lower EWR when the Ip is below 8 A. On the other hand, copper composite with 3.0 wt % MWCNT has the best MRR up to 33 % by using the Ip at 18 A.

博士
國立交通大學
機械工程系所
107
In this study, we applied an argon-based round atmospheric-pressure plasma jet (APPJ) on wound healing of diabetic rats and human blood coagulation of human. The APPJ was characterized its basic optical properties, also measured its temperature (37~40 ºC) and observed histology of rat skin after 10-min exposure to confirm this APPJ is suitable for biomedical use. We only conducted the investigation of human blood coagulation using APPJ was mainly because it is the first step in the wound healing process and is much easier to perform direct experiments. We induced Type 1 and Type 2 diabetes, respectively, via high (60 mg/kg) and low (30 mg/kg) doses of streptozotocin (STZ) injection in combination with normal and high-fat diet. The wounds with 8 mm in diameter were treated for 120 s once daily. The wound area ratio of all daily plasma-treated normal and diabetic wounds were significantly reduced up to 30~40 % as compared to the untreated groups in the middle healing stage. The Hematoxylin and Eosin staining and Masson’s trichrome staining showed higher re-epithelialization and collagen deposition levels by APPJ treatment, respectively. However, the inflammation decreased after plasma treatment. The immunohistochemistry results showed higher levels of angiogenesis and transforming growth factor beta in plasma treatment groups as compared to control groups in the early stage, while decreased in the middle and late stage. For the larger-size wounds with 21 mm in diameter, the 240-second treatment could significantly improve wound healing speed as well. Furthermore, in detection of antioxidants, the results showed that the levels of superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) were generally increased after plasma treatment, which proved the participation of reactive species in wound healing. In the coagulation model, we found that the bleeding time decreased after 15- and 30-second APPJ treatment. In addition, the clotting times of normal and anticoagulant-added bloods were significantly decreased with the increasing APPJ treatment time as compared with untreated and pure argon gas treated groups. The SEM results exhibited faster fibrin clot formation and higher platelet activation levels by APPJ exposure. The prothrombin time (PT) and activated partial thromboplastin time (aPTT) tests revealed that the argon APPJ might activate the intrinsic pathway of coagulation cascade due to the unchanged PT and decreasing aPTT (35.9 s to 32.2 s). By adding various inhibitors of specific coagulation factors, we found that APPJ might active factor XII, XI, IX, and VIII during the APPJ treatment.

碩士
國立交通大學
機械工程系所
106
Among the skin and nail diseases, Green Nail Syndrome (GNS) and Onychomycosis are two of the most common nail diseases. They often require treatment for months, which is a relatively long time. In this study, an argon-based round non-thermal atmospheric pressure plasma jet (APPJ) was used as an treatment device because it can provide appreciable OH, which is believed to be one of the key roles for sterilization. To confirm the sterilization efficiency of plasma jet, the pathogens of green nails and gray nails: Pseudomonas aeruginosa (ATCC 25619) , Candida albicans (ATCC 18804) and fungi were used as target strains. The inhibition area, inhibition rate, scanning electron microscope (SEM) and penetration efficacy test were used to analyze the sterilization result and penetration efficiency after different plasma treatment times. After measuring plasma jet sterilization efficiency, target strains on human nail were inoculated to mimic real disease, and then the plasma jet was used to treat the infected nails with different treating times. After plasma treatment, the colony count method was used to evaluate the sterilization efficiency and the scanning electron microscope was applied to observe the structure change and the amount of bacteria inside nail sample before and after plasma treatment.

The GERDA experiment searches for the neutrinoless double beta (0𝜈𝛽𝛽) decay of Ge-76. The observation of this decay would prove the Majorana character of the neutrino, i.e. that it is its own antiparticle. This would clarify the question which neutrino mass ordering is realized in nature and give a hint of the effective Majorana neutrino mass. Furthermore, the existence of the 0𝜈𝛽𝛽 decay would imply the violation of lepton number conservation which is a key feature in some theories explaining the asymmetry of matter and antimatter in the universe. The effective Majorana neutrino mass is connected with the half life of the 0𝜈𝛽𝛽 decay via a nuclear matrix element (NME), which is predicted by various theoretical models that are afflicted by large uncertainties. The accuracy of the different NMEs and their internal model assumptions can be increased by considering experimental investigations. While the NMEs for the 0𝜈𝛽𝛽 decay and the neutrino accompanied double beta (2𝜈𝛽𝛽) decay are numerically different, they rely on similar model assumptions. Thus, experimental constraints can be given by the 2𝜈𝛽𝛽 decay into the ground state, which has been already measured by GERDA with unprecedented precision for Ge-76, but also by the investigation of the 2𝜈𝛽𝛽 decay into excited states, which has not yet been observed for Ge-76. GERDA operates enriched germanium detectors in liquid argon (LAr) which serves as an additional background veto using the scintillation light that is created when energy is deposited in LAr. The signal signature of the decay into excited states can be enhanced with the application of the LAr veto, however, for that the efficiency of the LAr veto needs to be determined. One of the key parameters of the LAr efficiency is the attenuation of the scintillation light in LAr, which is dependent on the impurity composition and concentration in LAr. Therefore, the attenuation length of the scintillation light in LAr has been measured in GERDA with a dedicated setup in the course of this work. The analysis of the acquired data required intense computer simulations in order to describe the background for the measurement sufficiently. This also involved the measurement of the steel reflectivity in the visible and the UV region, where LAr scintillates. Therewith, the search for excited states has been performed in this work for the data accumulated in GERDA Phase I, Phase II and Phase II+ including the LAr veto for the latter two data sets. New limits have been set on the investigated excited states decay modes and some of the corresponding theoretical half life predictions could be disfavored, i.e. the underlying NMEs models can be constrained. The successor experiment LEGEND will continue searching for the 0𝜈𝛽𝛽 decay of Ge-76 using more germanium detectors together with an improved LAr veto. The investigation of the decay of Ge-76 into excited states will also be further pursued in LEGEND.

One of the major technological innovations that are necessary for faster and cheaper access-to-space will be the commercial realization of supersonic combustion jet engines (SCRAMJET). The establishment of the flow through the inlet is one the prime requirement for the success of a SCRAMJET engine. The flow through a SCRAMJET inlet is dominated by inviscid /viscous coupling, transition, shock-shock interaction, shock boundary layer interaction, blunt leading edge effects and flow profile effects. Although the literature is exhaustive on various aspects of flow features associated with SCRAMJET engines, very little is known on the fundamental gasdynamic features dictating the flow establishment in the SCRAMJET inlet. On one hand we need the reduction of flight Mach number to manageable supersonic values inside the SCRAMJET combustor, but on the other hand we have to achieve this with minimum total pressure loss. Hence the dynamics of ramp/cowl shock interaction process ahead of the inlet has a direct bearing on the quality and type of flow inside the SCRAMJET engine. There is virtually no data base in the open literature focusing specifically on the cowl/ramp shock interactions at hypersonic Mach numbers. Hence in this backdrop, the main aim of the present investigation is to systematically understand the ramp/cowl shock interaction processes in front of a generic inlet model. Since we are primarily concerned with the shock interaction process ahead of the cowl all the investigations are carried out without any fuel injection. Variable geometry is necessary if we want to operate the inlet for a wide range of Mach numbers in actual flight. The investigation mainly comprises of three variable geometry configurations; namely, variation of contraction ratios at 00 cowl (CR 8.4, 5.0 and 4.3), variation of cowl length for a given chamber height (four lengths of cowls at 10 mm chamber height) and variation of cowl angle (three angles cowl each for two chamber heights). The change in cowl configuration results in different ramp/cowl shock interaction processes affecting the performance of the inlet. Experiments are performed in IISc hypersonic shock tunnel HST 2 (test time ~ 1 ms) at two nominal Mach numbers 8.0 and 5.74 for design and off-design testing conditions. Exhaustive numerical simulations are also performed to compliment the experiments. Further the effect of concentrated energy deposition on forebody /cowl shock interactions has also been investigated. A 2D, planar, single ramp scramjet inlet model has been designed and fabricated along with various cowl geometries and tested in a hypersonic shock tunnel to characterize the forebody/cowl shock interaction process for different inlet configurations. Further a DC plasma power unit and a plasma torch have been designed, developed and fabricated to serve as energy source for conducting flow-alteration experiments in the inlet model. The V-I characteristics of the plasma torch is studied and an estimation of plasma temperature is also performed as a part of characterizing the plasma flame. Initial standardization experiments of blunt body flow field alteration using the plasma torch and hence its drag reduction, are performed to check the torch’s suitability to be used as a flow-altering device in a shock tunnel. The plasma torch is integrated successfully with the inlet model in a shock tunnel to perform experiments with plasma jet as the energy source. The above experiments are first of its kind to be conducted in a shock tunnel. They are performed at various pressure ratios and supply currents. Time resolved schlieren flow visualization using Phantom 7.1 (Ms Vision Research USA) high speed camera, surface static pressure measurements inside a generic inlet using miniature kulite transducer and surface convective heat transfer rate measurements inside a generic inlet using platinum thin film sensors deposited on Macor substrate are some of the shock tunnel flow diagnostics that have been used in this study. Some of the important conclusions from the study are: • Experiments performed at different contraction ratios show different shock patterns. At CR 8.4, the SOL condition is satisfied, but the flow gets choked due to over contraction and flow through inlet is not established. For CR 5.0, formation of a small Mach stem before the chamber is observed with the reflection point on the cowl and the weak reflected shock entering inside the chamber. The Mach stem grows with time. For CR 4.3, the forebody/cowl shock interference created an Edney’s Type II shock interaction pattern. However, at off-design conditions, for CR 5 the shock reflection is regular and at CR 4.3, the Edney’s Type II pattern lasts for a short time. • For all lengths of cowl tested, 131mm and 141mm showed Edney’s Type II shock interference where as 151mm showed Edney’s Type I pattern at design condition. In all cases the flow is choked for high contraction ratio. At off-design condition these shock patterns do not last for the entire test time but rather it becomes a lambda pattern with the normal shock before the inlet. • For inlet configurations with cowl angle other than 00, the flow is found to be established for all cases at designed condition and except for 100 cowl at off-design condition. • For CR 8.4 the peak value of pressure (~1.7x104 Pa) occurs at a location of 151mm, where as for CR 5.0 and 4.3 they occur at 188mm and 206mm having values ~1.6x104 Pa and ~1.4x104 Pa respectively. These locations indicate the likely locations of shock impingements inside the chamber. • For cowl angle of 00 for a 10 mm chamber the maximum pressure value recorded is ~1.7x104 Pa whereas for 100 and 200 cowl it is ~1.1x104 Pa and 1.2 x104 Pa respectively. This is because in the first case the inlet is choked because of over contraction whereas in the other two cases the CR is less and flow is established inside the inlet. • The average heat transfer rates of last four heat transfer gauges (180 mm, 190 mm, 200 mm and 210 mm from the forebody tip) for all lengths of cowls tested are found to be almost same (~ 20 W/cm2). This is because the flow is choked in all these cases. The numerical simulation also shows uniform distribution here, consistent with the experimental findings. • The locations of heat transfer peaks for 100 cowl at design condition can be observed to be occurring at 170 mm and 200 mm from the forebody tip having values ~44 W/cm2 and ~39 W/cm2 respectively. For a 200 cowl they seem to be occurring at 170 mm and 180 mm from the forebody tip having values ~50 W/cm2 and ~30 W/cm2. These locations indicate the likely locations of shock impingements inside the chamber. With the evolution of concept of upstream fuel injection in recent times these may the most appropriate locations for fuel injection. • At higher jet pressure ratios the plasma jet/ramp shock interaction results in a lambda shock pattern with the triple point forming vertically above the cowl level. This means the normal shock stands in front of the inlet making a part of the flow entering the inlet subsonic. The reflected shock from the triple point also separates the ramp boundary layer. • At lower jet pressure ratios the triple point is formed below the cowl level and the flow entering inside the inlet is supersonic. The reflected shock interacts with the cowl shock and a weak separation shock is seen. • Experiments are performed with concentrated DC electric discharge as energy source. Even though the amount of energy dumped here is less than 0.25% of the total energy it creates a perceptible disturbance in the flow. • Experiments are also performed to see the effect of electric discharge as energy source on height of Mach stem for a given inlet configuration. Deposition of energy in the present location does not seem to alter the Mach stem height. However more experiments need to be performed by varying the energy location to see its effect. Non-intrusive energy sources like microwave and lasers can be thought of as options for depositing energy to study its effect on Mach stem height. Since they provide more flexibility on varying the location of energy the optimum location of energy can be found out for highest reduction of Mach stem height.

One of the major technological innovations that are necessary for faster and cheaper access-to-space will be the commercial realization of supersonic combustion jet engines (SCRAMJET). The establishment of the flow through the inlet is one the prime requirement for the success of a SCRAMJET engine. The flow through a SCRAMJET inlet is dominated by inviscid /viscous coupling, transition, shock-shock interaction, shock boundary layer interaction, blunt leading edge effects and flow profile effects. Although the literature is exhaustive on various aspects of flow features associated with SCRAMJET engines, very little is known on the fundamental gasdynamic features dictating the flow establishment in the SCRAMJET inlet. On one hand we need the reduction of flight Mach number to manageable supersonic values inside the SCRAMJET combustor, but on the other hand we have to achieve this with minimum total pressure loss. Hence the dynamics of ramp/cowl shock interaction process ahead of the inlet has a direct bearing on the quality and type of flow inside the SCRAMJET engine. There is virtually no data base in the open literature focusing specifically on the cowl/ramp shock interactions at hypersonic Mach numbers. Hence in this backdrop, the main aim of the present investigation is to systematically understand the ramp/cowl shock interaction processes in front of a generic inlet model. Since we are primarily concerned with the shock interaction process ahead of the cowl all the investigations are carried out without any fuel injection. Variable geometry is necessary if we want to operate the inlet for a wide range of Mach numbers in actual flight. The investigation mainly comprises of three variable geometry configurations; namely, variation of contraction ratios at 00 cowl (CR 8.4, 5.0 and 4.3), variation of cowl length for a given chamber height (four lengths of cowls at 10 mm chamber height) and variation of cowl angle (three angles cowl each for two chamber heights). The change in cowl configuration results in different ramp/cowl shock interaction processes affecting the performance of the inlet. Experiments are performed in IISc hypersonic shock tunnel HST 2 (test time ~ 1 ms) at two nominal Mach numbers 8.0 and 5.74 for design and off-design testing conditions. Exhaustive numerical simulations are also performed to compliment the experiments. Further the effect of concentrated energy deposition on forebody /cowl shock interactions has also been investigated. A 2D, planar, single ramp scramjet inlet model has been designed and fabricated along with various cowl geometries and tested in a hypersonic shock tunnel to characterize the forebody/cowl shock interaction process for different inlet configurations. Further a DC plasma power unit and a plasma torch have been designed, developed and fabricated to serve as energy source for conducting flow-alteration experiments in the inlet model. The V-I characteristics of the plasma torch is studied and an estimation of plasma temperature is also performed as a part of characterizing the plasma flame. Initial standardization experiments of blunt body flow field alteration using the plasma torch and hence its drag reduction, are performed to check the torch’s suitability to be used as a flow-altering device in a shock tunnel. The plasma torch is integrated successfully with the inlet model in a shock tunnel to perform experiments with plasma jet as the energy source. The above experiments are first of its kind to be conducted in a shock tunnel. They are performed at various pressure ratios and supply currents. Time resolved schlieren flow visualization using Phantom 7.1 (Ms Vision Research USA) high speed camera, surface static pressure measurements inside a generic inlet using miniature kulite transducer and surface convective heat transfer rate measurements inside a generic inlet using platinum thin film sensors deposited on Macor substrate are some of the shock tunnel flow diagnostics that have been used in this study. Some of the important conclusions from the study are: • Experiments performed at different contraction ratios show different shock patterns. At CR 8.4, the SOL condition is satisfied, but the flow gets choked due to over contraction and flow through inlet is not established. For CR 5.0, formation of a small Mach stem before the chamber is observed with the reflection point on the cowl and the weak reflected shock entering inside the chamber. The Mach stem grows with time. For CR 4.3, the forebody/cowl shock interference created an Edney’s Type II shock interaction pattern. However, at off-design conditions, for CR 5 the shock reflection is regular and at CR 4.3, the Edney’s Type II pattern lasts for a short time. • For all lengths of cowl tested, 131mm and 141mm showed Edney’s Type II shock interference where as 151mm showed Edney’s Type I pattern at design condition. In all cases the flow is choked for high contraction ratio. At off-design condition these shock patterns do not last for the entire test time but rather it becomes a lambda pattern with the normal shock before the inlet. • For inlet configurations with cowl angle other than 00, the flow is found to be established for all cases at designed condition and except for 100 cowl at off-design condition. • For CR 8.4 the peak value of pressure (~1.7x104 Pa) occurs at a location of 151mm, where as for CR 5.0 and 4.3 they occur at 188mm and 206mm having values ~1.6x104 Pa and ~1.4x104 Pa respectively. These locations indicate the likely locations of shock impingements inside the chamber. • For cowl angle of 00 for a 10 mm chamber the maximum pressure value recorded is ~1.7x104 Pa whereas for 100 and 200 cowl it is ~1.1x104 Pa and 1.2 x104 Pa respectively. This is because in the first case the inlet is choked because of over contraction whereas in the other two cases the CR is less and flow is established inside the inlet. • The average heat transfer rates of last four heat transfer gauges (180 mm, 190 mm, 200 mm and 210 mm from the forebody tip) for all lengths of cowls tested are found to be almost same (~ 20 W/cm2). This is because the flow is choked in all these cases. The numerical simulation also shows uniform distribution here, consistent with the experimental findings. • The locations of heat transfer peaks for 100 cowl at design condition can be observed to be occurring at 170 mm and 200 mm from the forebody tip having values ~44 W/cm2 and ~39 W/cm2 respectively. For a 200 cowl they seem to be occurring at 170 mm and 180 mm from the forebody tip having values ~50 W/cm2 and ~30 W/cm2. These locations indicate the likely locations of shock impingements inside the chamber. With the evolution of concept of upstream fuel injection in recent times these may the most appropriate locations for fuel injection. • At higher jet pressure ratios the plasma jet/ramp shock interaction results in a lambda shock pattern with the triple point forming vertically above the cowl level. This means the normal shock stands in front of the inlet making a part of the flow entering the inlet subsonic. The reflected shock from the triple point also separates the ramp boundary layer. • At lower jet pressure ratios the triple point is formed below the cowl level and the flow entering inside the inlet is supersonic. The reflected shock interacts with the cowl shock and a weak separation shock is seen. • Experiments are performed with concentrated DC electric discharge as energy source. Even though the amount of energy dumped here is less than 0.25% of the total energy it creates a perceptible disturbance in the flow. • Experiments are also performed to see the effect of electric discharge as energy source on height of Mach stem for a given inlet configuration. Deposition of energy in the present location does not seem to alter the Mach stem height. However more experiments need to be performed by varying the energy location to see its effect. Non-intrusive energy sources like microwave and lasers can be thought of as options for depositing energy to study its effect on Mach stem height. Since they provide more flexibility on varying the location of energy the optimum location of energy can be found out for highest reduction of Mach stem height.

Experiments and numerical models were used to investigate an inductively coupled plasma source (ICPS) operating with a magnetic filter field. The work shows that applying magnetic filters transversely to the plasma offers several new control parameters to help enhance the properties of a plasma source. The application of these new results using magnetic enhancement is discussed with respect to both industrial plasma fabrication processes and neutral beam injection for fusion power. Experimental measurements of the power transfer efficiency of the ICPS were undertaken comparing the effect of the magnetic field for both hydrogen and argon plasmas. The location and strength of the magnetic field was varied while measurements of the plasma resistance and power transfer efficiency were performed. The changes in forward power transfer were correlated with plasma density measurements and a numerical model of the electrical plasma circuit was used to guide the optimal choice for the power system components. The results demonstrate that the magnetic field increases the total efficiency of the plasma source and that the gains are strongly dependant on the choice of location for the magnetic field. Plasma properties were then investigated across the plasma source 1 cm intervals. Experimental measurements comparing the effect of the magnetic filter on the plasma properties include: electron densities using a hairpin probe, electron energy probability functions using a compensated Langmuir probe, negative ion densities by laser photo detachment and rotational gas temperatures by optical emission spectroscopy. These measurements revealed interesting new properties of the plasma when a magnetic filter is applied including: the formation of a high density cold particle trap, changes in particle transport and drift motions, increased gas temperatures, and a peak in negative ion density under the magnetic filter center. Pulsing the plasma can greatly affect the plasma dynamics, leading to electron cooling in the afterglow and increased negative ion production. A combination of a pulsed plasma with a magnetic filter was then investigated. Measurements of the negative ion and electron populations were performed in the plasma afterglow with the magnetic filter applied. The results reveal a complex and dynamic afterglow process including strong spatial dependencies measured for diffusive transport, ambipolar breakdown and ion-ion plasma formation. The applications for this work include offering new avenues for control over processing plasma chemistry as well as initial results toward the future viability of a caesium-free pulsed negative ion neutral beam source.