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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.
11

Development of an advanced nanocalorimetry system for rapid material characterizations

Liu, Yen-Shan 25 April 2007 (has links)
The development of a versatile system capable of providing rapid, portable, and inexpensive detection of explosives and energetic compounds is needed critically to offer an enhanced level of protection against current and future threats to homeland security, as well as to satisfy a wide range of applications in the fields of forensic analysis, emergency response, and industrial hazards analysis. The hand-held nanocalorimeter will serve as a first-of-its-kind screening tools for explosive and energetic compounds directly in the settings where they are needed with high efficiency, reduced cost, and simplicity with ease of use. Unlike current explosives detectors, this system is based on calorimetric techniques that are inherently capable of providing direct measurements of energy release potential and therefore do not depend on prior knowledge of familiar compounds. The microfabricated calorimetry instrument consists of (i) a thermal control module incorporating arrays of microfabricated heaters and temperature sensors, as well as any necessary electronic interconnections, and (ii) a sample encapsulation module incorporating etched enclosures designed to accommodate either solid or liquid samples. Initial work has led to successful fabrication of a chip capable of sampling nano-sized solid or liquid compounds. Control algorithms incorporating the DSC principle have also been written using LabVIEW. Device performance of the original and redesigned chips were tested by studying the thermal transitions associated with the boiling points of acetone and pentane. With the redesigned chip, the heat loss issue was reduced: the measured input heat was reduced from 32 times of the required energy to 5 times of the required energy. Future work will focus on modifying the chip design and control algorithm to improve accuracy and sensitivity, developing a trace analysis software to link it to a database of explosive information, and adapting different fabrication procedures for high temperature operation and large scale production.
12

Generation of Electromagnetic Ion Cyclotron (EMIC)Waves in a Compressed Dayside Magnetosphere

Usanova, Maria Unknown Date
No description available.
13

Analytical and numerical investigation of energetic particles interacting with turbulent magnetic fields

Heusen, Martin H. 24 January 2017 (has links)
A fundamental problem in astrophysics is the interaction between space plasmas and energetic particles. Plasmas form the vast majority of space and can be found in any astrophysical environment, from the plasma of the solar wind to the interstellar medium for example. When plasmas stream through space, they give rise to turbulent magnetic fields. In addition, space is populated by energetic particles whose origins could be interplanetary, such as solar energetic particles generated by explosions on the surface of the Sun, or Galactic, such as cosmic rays generated by supernova remnants. As these particles propagate through interplanetary or interstellar space, they experience scattering due to magnetic turbulence. Describing these scattering effects, through the calculation of diffusion coefficients, is crucial to understanding several important processes in astrophysics. Such processes include particle acceleration at interplanetary shocks, solar modulation and space weather studies, and the motion of cosmic rays through galaxies. A test-particle code is developed to simulate the interaction of charged particles with turbulent magnetic fields. Diffusion coefficients along and across the mean magnetic field are calculated and compared with analytical theories and space mission measurements. Turbulence models with reduced dimensionality and full three-dimensional corresponding to different space settings are considered, including reproducing the magnetic turbulence in the solar wind and the interstellar medium. Wave propagation, dynamical effects, and unique turbulence setups such as noisy hydrodynamic models are also considered. We show that the influence of turbulence properties and various space regimes on transport parameters is minor and not as strong as originally thought. This points toward a universal transport behaviour of charged particles which motivates the employment of a comprehensive diffusion formula for different space settings. In addition, we were able for the first time to accurately describe the interaction between Galactic cosmic rays and dynamical solar wind turbulence to reproduce observational results of mean free paths. The validity of certain asymptotic limits for the parallel and perpendicular diffusion coefficients are examined. It is shown that only two parameters control those limits, namely the fundamental length scale of magnetic turbulence and the ratio of turbulence strength to the mean field. / February 2017
14

Geomagnetic perturbations on stratospheric circulation in late winter and spring

Lu, Hua, Clilverd, Mark A., Seppälä, Annika, Hood, Lon L. 22 August 2008 (has links)
This study investigates if the descent of odd nitrogen, generated in the thermosphere and the upper mesosphere by energetic particle precipitation (EPP-NOx), has a detectable impact on stratospheric wind and temperature in late winter and spring presumably through the loss of ozone and reduction of absorption of solar UV. In both hemispheres, similar downward propagating geomagnetic signals in the extratropical stratosphere are found in spring for those years when no stratospheric sudden warming occurred in mid-winter. Anomalous easterly winds and warmer polar regions are found when the 4-month averaged winter Ap index (Ap) is high, and the signals become clearer when solar F10.7 is low. In May, significant geomagnetic signals are obtained in the Northern Hemisphere when the data are grouped according to the phase of the stratospheric equatorial QBO. The magnitudes of changes in spring stratospheric wind and temperatures associated with Ap signals are in the range of 10–20 m s−1 and 5–10 K, which are comparable with those of the 11-yr SC signals typically found in late winter. The spring Ap signals show the opposite sign to that expected due to in situ cooling effects caused by catalytic destruction of stratospheric ozone by descending EPP-NOx. Thus it is unlikely that the in situ chemical effect of descending EPP-NOx on stratospheric ozone would have a dominant influence on stratospheric circulation. Instead, we suggest that the detected Ap signals in the extratropical spring stratosphere may be an indirect consequence of geomagnetic and solar activity, dynamically induced by changes in wave ducting conditions.
15

Development of a low cost cook-off test for assessing the hazard of explosives

Frota, Octávia January 2015 (has links)
A low cost Cook-Off experimental facility has been established to provide a convenient method of ranking explosives in their response to Cook-Off by the time to event under two widely different heating rates and at two different scales. This thesis describes the literature review undertaken as preparation for the purposed study and all the experimental work developed comprising the design of the trials vehicles, the demonstration of their suitability for Fast and Slow Cook-Off trials with confined explosive systems, the preparation of the samples and test vehicles to be trialled as well as the set-up of adequate facilities to undertake the scheduled firing programme. Results are reported for Cook-Off tests on TNT, RDX, and their mixtures. The emphasis of the study is on time to event, and temperature at event, and in addition a qualitative assessment of the violence of the event was made by examination of the fragments of the vehicles, although it is accepted that the relatively light and low cost design of the vehicle may lead to variable confinement in the early stages of the explosive event, and hence to a wider spread of responses than would be obtained from a more heavily confined and more costly vehicle. The test vehicles give results, which differentiate between the various explosives and explosive mixtures trialled and between the scales. More experiments are required to establish the reproducibility of the measurements. The design of the equipment makes this a relatively inexpensive undertaking. The experiment was modelled using published kinetic data, but the calculated time to event differed from that observed to different extents at the two scales. It is hypothesised that the mechanism may change over the prolonged heat soaks and that quantitative scaling is not possible with the available information. Further work is also suggested using a different type of Cook-Off test vehicle, which will in our opinion reduce even further the cost of Cook-Off testing, due to reduction in man-hours of preparation involved and manufacture cost of the Cook-Off test vehicles, and consequently of ranking of explosives.
16

Development of a low cost cook-off test for assessing the hazard of explosives

Frota, O 24 July 2015 (has links)
A low cost Cook-Off experimental facility has been established to provide a convenient method of ranking explosives in their response to Cook-Off by the time to event under two widely different heating rates and at two different scales. This thesis describes the literature review undertaken as preparation for the purposed study and all the experimental work developed comprising the design of the trials vehicles, the demonstration of their suitability for Fast and Slow Cook-Off trials with confined explosive systems, the preparation of the samples and test vehicles to be trialled as well as the set-up of adequate facilities to undertake the scheduled firing programme. Results are reported for Cook-Off tests on TNT, RDX, and their mixtures. The emphasis of the study is on time to event, and temperature at event, and in addition a qualitative assessment of the violence of the event was made by examination of the fragments of the vehicles, although it is accepted that the relatively light and low cost design of the vehicle may lead to variable confinement in the early stages of the explosive event, and hence to a wider spread of responses than would be obtained from a more heavily confined and more costly vehicle. The test vehicles give results, which differentiate between the various explosives and explosive mixtures trialled and between the scales. More experiments are required to establish the reproducibility of the measurements. The design of the equipment makes this a relatively inexpensive undertaking. The experiment was modelled using published kinetic data, but the calculated time to event differed from that observed to different extents at the two scales. It is hypothesised that the mechanism may change over the prolonged heat soaks and that quantitative scaling is not possible with the available information. Further work is also suggested using a different type of Cook-Off test vehicle, which will in our opinion reduce even further the cost of Cook-Off testing, due to reduction in man-hours of preparation involved and manufacture cost of the Cook-Off test vehicles, and consequently of ranking of explosives.
17

Studies of novel nitro-substituted nitrogen heterocyclic compounds

Philbin, Simon Patrick January 2001 (has links)
The novel candidate high energy insensitive explosive; 2,5-diamino-3,6-dinitropyrazine (ANPZ-i) has been prepared in acceptable overall yield. ANPZ-i was synthesised by the nitration of 2,5-diethoxypyrazine using nitronium tetrafluoroborate (NO2+BF4-) in sulfolane and the subsequent amination of 2,5-diethoxy-3,6-dinitropyrazine, under autoclave conditions. Oxidation studies towards the dioxide derivative of ANPZ-i, 2,5-diamino-3,6-dinitropyrazine-1,4-dioxide (PZDO), were unsuccessful. The synthesis of existing high explosives; 2,6-diamino-3,5-dintropyrazine (ANPZ) and 2,6-diamino-3,5-dinitropyrazine-1-oxide (PZO) has been scaled up to produce approximately 25 g batches of material. A number of novel nitrations using NO2+BF4- have been carried out on a range of chloro-, methyl- and hydroxy-functionalised quinoxalines and quinazolines. A range of novel functionalisations have also been carried out on the platform molecule; 2,4-diamino-6,8-dinitroquinazoline giving rise to 2,4-diamino-6,8-dinitroquinazoline-1,3-dioxide (di-N-oxidation product), 2,4,7-triamino-6,8-dinitroquinazoline (monoamination product) and 2,4,6,8-tetra-aminoquinazoline (dihydrogenation product). Detonics molecular modelling was carried out on the following target molecules: 2,5-diamino-3,6-dinitropyrazine-1,4-dioxide (PZDO), 2,5,8-triamino-3,6,7-trinitroquinoxaline-1-oxide and 2,5,7-triamino-4,6,8-trinitroquinazoline-1-oxide. The detonation velocity of the new explosive molecule; 2,5-diamino-3,6-dinitropyrazine (ANPZ-i) was calculated and it was found to be a similar value to that obtained experimentally for the existing high explosive RDX. Calculation by molecular modelling of the steric energies of ANPZ, PZO, ANPZ-i and PZDO gave a quantitative assessment of the difficulty in oxidising ANPZ-i to give PZDO. Extensive analysis of carbon-13 NMR spectroscopy shift values was carried out for approximately twenty nitrogen heterocyclic compounds. Comparison of shift values indicated consistency in the interpretations. On-line literature searches have shown that the following compounds prepared in this project are new: 2,3,6-trichloro-5-nitroquinoxaline, 2,3-dimethoxy-6,7-dinitroquinoxaline, 2,3,6-trichloroquinoxaline-1-oxide, 2,4-diamino-6,8-dinitroquinazoline-1,3-dioxide, 2,4,7-triamino-6,8-dinitroquinazoline and 2,5-diamino-3,6-dinitropyrazine (ANPZ-i). Furthermore, new synthetic routes have been used in the preparation of the following compounds: 2,3-dichloro-5-nitroquinoxaline, 2,3,6,7-tetrachloro-5-nitroquinoxaline, 2-hydroxy-6-nitroquinoxaline, 2-hydroxy-3-methyl-6-nitroquinoxaline and 2,5-diethoxy-3,6-dinitropyrazine.
18

Ion-materials interactions and their application

Whitlow, Harry James January 1998 (has links)
No description available.
19

Διερεύνηση της δυνατότητας εκπονήσεως ενός πραξιοκεντρικού προγράμματος για το νηπιαγωγείο

Καραΐνδρου, Αθανασία 16 January 2009 (has links)
Η συγκεκριμένη εργασία διερευνά τη δυνατότητα εκπονήσεως ενός πραξιοκεντρικού προγράμματος για το Νηπιαγωγείο. Αρχικά, μελετάται η εξελικτική πορεία των προγραμμάτων προσχολικής αγωγής μέχρι και σήμερα. Στη συνέχεια, διερευνάται η δυνατότητα και ο τρόπος εκπονήσεως ενός τέτοιου αυτενεργητικού προγράμματος στα πλαίσια του σύγχρονου Νηπιαγωγείου. Ο συγγραφέας, συγκεκριμένα, επικεντρώνεται στην προσπάθεια διαμόρφωσης προγραμμάτων προσχολικής αγωγής προκειμένου να βοηθηθούν τα νήπια να γίνουν παραγωγικά και υπεύθυνα μέλη της κοινωνίας. Άλλωστε με την εισαγωγή του παιδιού στο Νηπιαγωγείο, παρατηρείται μετάβασή απ’ το οικογενειακό περιβάλλον, στο άγνωστο περιβάλλον του κοινωνικού πλαισίου. Κατά συνέπεια, αρχίζει να προγεύεται τους κανόνες της κοινωνικής ή ηθικής συμβίωσης και να σχηματοποιεί τις βάσεις της προσωπικότητάς του. Επιπροσθέτως, επισημαίνεται ότι οι παιδαγωγικώς κατάλληλες ευκαιρίες για σκέψη, μάθηση, δράση και συμμετοχή εξασφαλίζονται μόνο σε ένα καλώς οργανωμένο και σκοπίμως διαρθρωμένο παιδαγωγικό περιβάλλον. Έτσι, προϋπόθεση των παραπάνω αποτελεί η εφαρμογή ενός προγράμματος στο Νηπιαγωγείο, που «αναδύεται και βιώνεται», «συν- δημιουργείται» από τα νήπια και τη νηπιαγωγό, με τις πράξεις τους και τις επιδράσεις τους καθώς και με την αλληλοεμπλοκή της ζωής τους. Κατά την άποψή μας, όποιο πρόγραμμα και αν επιλέξει μια νηπιαγωγός να εφαρμόσει, πρέπει να θέτει ως βασική αρχή τη δυνατότητα να αναλαμβάνουν τα νήπια πρωτοβουλίες, καθώς και να έχουν την ευθύνη για τη μάθησή τους. Τέλος, κρίνεται σκόπιμο να επισημανθεί ότι η κρισιμότητα της πρώιμης αυτής ηλικίας των παιδιών «απαιτεί» ιδιαίτερη προσοχή και έμφαση στα εφαρμοζόμενα προσχολικά προγράμματα, διότι αυτά θα «αναδείξουν» τους πολίτες του 21ου αιώνα. / The particular work investigates the possibility of development of an action- central program for the Kindergarten. Initially, is studied the evolutionary course of programs of preschool education until today. Afterwards, are investigated the possibility and the way of development of such auto- energetic program in the frames of modern Kindergarten. The writer, concretely, is focused in the effort of configuration of programs of preschool education so that they be helped the infants become productive and responsible members of society. Moreover, with the import of child in the Kindergarten, is observed passage by the familial environment, in the unknown environment of social frame. Accordingly, it begins tasting the rules the social or moral living together and it shapes the bases of his personality. Besides, it is pointed out that the pedagogically suitable occasions for thought, learning, action and attendance are ensured only in a well organised and deliberately structured pedagogic environment. Thus, condition more constitutes the application of program in the Kindergarten, that “emerges and experiences”, “plus is created” by the infants and the nursery teacher, with their action and their effects as well as with the entanglement of their lives. At our opinion, any program if a nursery teacher selects to applying, it should it places as basic beginning the possibility of undertaking the children’s initiatives, as well as of having the responsibility for their learning. Finally, it’s judged advisable that the gravity of this precocious age of children “requires” particular attention and accent in the applied preschool programs, because these would “elect” the citizens of 21st century.
20

Marketing společnosti zajišťující energetické úspory / Marketing of the company mediating energetic savings

Jančík, Jan January 2011 (has links)
This diploma thesis outlines how a company doing business in mediation of energy savings could efficiently integrate marketing into its activities. The theoretical part defines the differences between marketing of services and introduces concepts that are later on used for analyzing of the target company. The practical part is focusing on examining of macro surroundings through PEST analysis and in examination of micro surroundings all the involved stakeholders that may substantially affect the functioning of the company are identified. Then the closest competition is revealed and its strengths are inspected in order to form recommendations of activities that should be integrated within the company's portfolio. These findings are then confronted with the objectives of observed company in the SWOT matrix and on its basis a marketing mix is created including the proposed tactical tools.

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