<p>Like the rest of the society modern health care has to deal with the ever increasing information flow. Imaging modalities such as CT, MRI, US, SPECT and PET just keep producing more and more data. Especially CT and MRI and their 3D image stacks cause problems in terms of how to effectively handle these data sets. Usually a PACS is used to manage the information flow. Since a PACS often is implemented with a server-client setup, the management of these large data sets requires an efficient representation of medical image stacks that minimizes the amount of data transmitted between server and client and that efficiently supports the workflow of a practitioner.</p><p>In this thesis an efficient wavelet representation for large medical image stacks is proposed for the use in a PACS. The representation supports features such as lossless viewing, random access, ROI-viewing, scalable resolution, thick slab viewing and progressive transmission. All of these features are believed to be essential to form an efficient tool for navigation and reconstruction of an image stack.</p><p>The proposed wavelet representation has also been implemented and found to be better in terms of memory allocation and amount of data transmitted between server and client when compared to prior solutions. Performance tests of the implementation has also shown the proposed wavelet representation to have a good computational performance.</p>

In this thesis, a long-term operation direct methanol fuel cell (DMFC) stack is developed. In order to reach this goal required in many ways, including select highly chemical stability materials, operating conditions must also be stable, and avoid changing the MEA structure when preserved, then can cause the DMFC to maintain stable operation for a long time. First of all, in order to avoid contaminating electrode, this study find out the chemical instability materials. Second, this study design a device which does not require power then can stability supply consumption fuel, and apply this device in 16-cell DMFC. Finally compare with continuous fuel supply and without fuel supply, two operating conditions performance stability. From these experiments can find out, the DMFC indeed in stable operation for a long time under the appropriate supplement. Traditional fuel supply systems typically using the pump fuel recycling, so the structure is more complex, difficult to reduce the volume, and not conducive to carry. If using a passive operation, fuel completely stored in the reaction Chamber, even though the structure is simple there will be a problem with fuel supply. In recent years, someone use vapors of methanol to supply the fuel, although can use high concentration methanol to extend operating time, but the evaporation rate is difficult to control, the fuel can¡¦t be supplied in time, especially when the large current is needed, and CROSSOVER issues would be difficult to overcome. In our 16-cell DMFC, continues to add appropriate amount of fuel consumed which according to the different current. The fuel supply device with a sliding control plate which can control methanol and water diffusion rate respectively. This device only to provide consumed by reaction and leaked fuel in anode chamber, so that the methanol concentration can maintained in the proper range at anode chamber. This device only use diffusion and gravity effects, don't use a fuel pump, so will not consume DMFC power.

Abstract A one-watt portable air-breathing direct methanol fuel cell stack (called DMFC), which can supply fuel passively and operate steadily, is developed in this thesis. A DMFC to maintain its performance stable, the most important strategy is to keep the methanol concentration in reacting chamber to be proper and stable. A fuel supplying system will be in accordance with the depletion of chemical reaction and the leakage of fuel under different circuit current to supplying fuel. To regulate the methanol and water supplying, a fuel supplying system by gravitation and diffusion forces deliver methanol and water to fill up the consumed fuel to maintain the concentration of methanol solution in anode reaction chamber, by adjusting a sliding gate to control the area of a diffusive membrane and utilizing three cotton threads and hoses to distribute the fuel to proper location. In doing so, the methanol concentration in the anode chamber can keep within an appropriate range, so that the DMFC stack can operate stably for a longer period. Yet the diffusivity of the diffusive membrane is comparatively less, the supply system is not easy to downsize. To reduce the size of portable DMFC, we make use of a fuel plug tank to combine the supply tank and reacting chamber, and thus the cell package is more portable. Between the plug tank and the reacting chamber, the three cotton threads are used to distribute the fuel to proper location. The above two design with no extra auxiliary device; therefore, no extra energy will be consumed. To reduce the fuel leakage, and make more use of fuel, four block films is pasted on the bare area of the nafion membranes in a 16-cell DMFC stack. If no fuel is fed into reaction chamber, this will prolong the cell operation time. Under the condition of 3.7 V (cell phone rated voltage) and the operating current 225 mA, our experiments display that the stacks with the two fuel supplying systems can continuously operate for more than 3 hours with no obvious change in methanol concentration within reaction chamber. The experimental results show that this simple passive fuel supplemental system can really keep the DMFC stack operating stably for a sufficient long period.

Introduction The Los Alamos Isotope Production Program commonly irradiates target stacks consisting of high, medium and low-energy targets in the “A-”, “B-”, and “C-slots”, respectively, with a 100MeV proton beam. The Program has recently considered the production of 57Co (t1/2 = 271.74 d, 100% EC) from 58Ni using the low-energy posi-tion of the Isotope Production Facility, down-stream of two RbCl salt targets. Initial MCNPX/ CINDER’90 studies predicted 57Co radioisotopic purities >90% depending on time allotted for decay. But these studies do not account for broadening of the proton beam’s energy distribution caused by density changes in molten, potentially boiling RbCl targets upstream of the 58Ni (see e.g., [1]). During a typical production with 230 µA average proton intensity, the RbCl targets’ temperature is expected to produce beam energy changes of several MeV and commensurate effects on the yield and purity of any radioisotope irradiated in the low-energy posi-tion of the target stack. An experiment was designed to investigate both the potential for 57Co’s large-scale production and the 2-dimensional proton beam energy distribution. Material and Methods Two aluminum targets holders were fabricated to each contain 31 58Ni discs (99.48%, Isoflex, CA), 4.76 mm (Φ) x 0.127 mm (thickness). Each foil was indexed with a unique cut pattern by EDM with a 0.254 mm brass wire to allow their position in the target to be tracked through hot cell disassembly and assay (see FIG. 1). Brass residue from EDM was removed with HNO3/HCl solution. The holders’ front windows were 2.87 and 1.37 mm thick, corresponding to predicted average incident energies of 17.9 and 24.8 MeV on the Ni [2]. Each target was irradiated with protons for 1 h with an average beam current of 218 ± 3 µA to ensure an upstream RbCl target temperature and density that would mimic routine production. Following irradiation, targets were disassembled and each disc was assayed by HPGe γ-spectroscopy. Residuals 56Co (t1/2 = 77.2 d, 100% EC) and 57Co have inversely varying measured nuclear formation cross sections between approximately 15 and 40 MeV. Results and Conclusion Distributions of 56,57,58,60Co were tracked as described in both irradiated targets. The distribution of activities matched expectations, with radioisotopes produced by proton interactions with the 58Ni target (56Co and 57Co) concentrated in the area struck by IPF’s rastered, annulus-shaped proton beam, and the distribution of radioisotopes produced by neutron-induced reactions (58Co and 60Co) relatively uniform across all irradiated foils. The potential range of such temperature variations predicted by thermal modeling (approx. ± 200 °C) corre-sponds to a density variation of nearly 0.2 g.cm−3, and a change in the average energy of protons incident on the low-energy “C-slot” of approximately 5 MeV, well-matched to the indi-rectly measured energy variation plotted in FIG. 3. No energy distribution in the plane per-pendicular to the beam axis has previously been assumed in the design of IPF targets. The effective incident energy measured by yields of 57Co and 56Co is, however, almost 5 MeV higher than those predicted using Anderson and Ziegler’s well-known formalism [2]. This discrepancy is supported by previous reports [3] and likely exacerbated compared to these reports by the large magnitude of energy degradation (from 100 MeV down to 30 MeV) in the IPF target stack. For more detailed discussion, refer to Marus et al.’s abstract, also reported at this meeting. While the experiments reported do confirm the potential for many Ci-scale yields of 57Co from months-long irradiations at the IPF, the level radioisotopic impurities 56Co and 58Co are concerning. Commercial radioisotope producers using U-150 (23 MeV) and RIC-14 (14 MeV) cyclotrons in Obninsk, Russia specify 56/58Co activities at levels <0.2% of available 57Co

This thesis consists of three articles treating topics in the theory of algebraic stacks. The first two papers deal with motivic invariants. In the first, we show that the class of the classifying stack BPGLn is the inverse of the class of PGLn in the Grothendieck ring of stacks for n ≤ 3. This shows that the multiplicativity relation holds for the universal torsors, although it is known not to hold for torsors ingeneral for the groups PGL2 and PGL3. In the second paper, we introduce an exponential function which can be viewed as a generalisation of Kapranov's motivic zeta function. We use this to derive a binomial theorem for a power operation defined on the Grothendieck ring of varieties. As an application, we give an explicit expression for the motivic class of a universal quasi-split torus, which generalises a result by Rökaeus. The last paper treats destackification. We give an algorithm for removing stackiness from smooth, tame stacks with abelian stabilisers by repeatedly applying stacky blow-ups. As applications, we indicate how the result can be used for destackifying general Deligne–Mumford stacks in characteristic zero, and to obtain a weak factorisation theorem for such stacks. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 2: Manuscript. Paper 3: Manuscript.</p>

Introduction The Los Alamos Isotope Production Program commonly irradiates target stacks consisting of high, medium and low-energy targets in the “A-”, “B-”, and “C-slots”, respectively, with a 100MeV proton beam. The Program has recently considered the production of 57Co (t1/2 = 271.74 d, 100% EC) from 58Ni using the low-energy posi-tion of the Isotope Production Facility, down-stream of two RbCl salt targets. Initial MCNPX/ CINDER’90 studies predicted 57Co radioisotopic purities >90% depending on time allotted for decay. But these studies do not account for broadening of the proton beam’s energy distribution caused by density changes in molten, potentially boiling RbCl targets upstream of the 58Ni (see e.g., [1]). During a typical production with 230 µA average proton intensity, the RbCl targets’ temperature is expected to produce beam energy changes of several MeV and commensurate effects on the yield and purity of any radioisotope irradiated in the low-energy posi-tion of the target stack. An experiment was designed to investigate both the potential for 57Co’s large-scale production and the 2-dimensional proton beam energy distribution. Material and Methods Two aluminum targets holders were fabricated to each contain 31 58Ni discs (99.48%, Isoflex, CA), 4.76 mm (Φ) x 0.127 mm (thickness). Each foil was indexed with a unique cut pattern by EDM with a 0.254 mm brass wire to allow their position in the target to be tracked through hot cell disassembly and assay (see FIG. 1). Brass residue from EDM was removed with HNO3/HCl solution. The holders’ front windows were 2.87 and 1.37 mm thick, corresponding to predicted average incident energies of 17.9 and 24.8 MeV on the Ni [2]. Each target was irradiated with protons for 1 h with an average beam current of 218 ± 3 µA to ensure an upstream RbCl target temperature and density that would mimic routine production. Following irradiation, targets were disassembled and each disc was assayed by HPGe γ-spectroscopy. Residuals 56Co (t1/2 = 77.2 d, 100% EC) and 57Co have inversely varying measured nuclear formation cross sections between approximately 15 and 40 MeV. Results and Conclusion Distributions of 56,57,58,60Co were tracked as described in both irradiated targets. The distribution of activities matched expectations, with radioisotopes produced by proton interactions with the 58Ni target (56Co and 57Co) concentrated in the area struck by IPF’s rastered, annulus-shaped proton beam, and the distribution of radioisotopes produced by neutron-induced reactions (58Co and 60Co) relatively uniform across all irradiated foils. The potential range of such temperature variations predicted by thermal modeling (approx. ± 200 °C) corre-sponds to a density variation of nearly 0.2 g.cm−3, and a change in the average energy of protons incident on the low-energy “C-slot” of approximately 5 MeV, well-matched to the indi-rectly measured energy variation plotted in FIG. 3. No energy distribution in the plane per-pendicular to the beam axis has previously been assumed in the design of IPF targets. The effective incident energy measured by yields of 57Co and 56Co is, however, almost 5 MeV higher than those predicted using Anderson and Ziegler’s well-known formalism [2]. This discrepancy is supported by previous reports [3] and likely exacerbated compared to these reports by the large magnitude of energy degradation (from 100 MeV down to 30 MeV) in the IPF target stack. For more detailed discussion, refer to Marus et al.’s abstract, also reported at this meeting. While the experiments reported do confirm the potential for many Ci-scale yields of 57Co from months-long irradiations at the IPF, the level radioisotopic impurities 56Co and 58Co are concerning. Commercial radioisotope producers using U-150 (23 MeV) and RIC-14 (14 MeV) cyclotrons in Obninsk, Russia specify 56/58Co activities at levels <0.2% of available 57Co

Vehicular Communication (VC) network technology is in the verge of real world deployment. The technology is aimed at achieving high levels of traffic efficiency security and comfort for the users of the traffic system. The technology facilitates exchange of awareness and notification messages among the vehicles to improve the traffic efficiency and safety of the drivers. However, deployment of this awesome technology faces several security and privacy risks. The system is subjected to security risks like replay attacks, nodes sending false information to the system, denial of service attacks by clogging the networks. System also faces several privacy challenges in which sensitive user data can be eavesdropped and also tracing out a particular node using the location data sent by the node. In this research we focused on protecting the privacy of the users using the VC system. Several European projects have been working on privacy enhancement techniques for VC environments. Privacy policy enforcement approach from Privacy Enabled Capability In Co-Operative Systems and Safety Applications (PRECIOSA), pseudonym approach from Secure Vehicular Communication (SeVeCom) and Preparing secure V2X Communication Systems (PRESERVE) project which integrates the results from both PRECIOSA and SeVeCom projects are three of those projects considered in this report. This research is more focused on the pseudonym approach proposed by SeVeCom. We discuss the impact of pseudonym change on the communication stack, what other lower layer identifiers need to be changed along with the pseudonym change, and is there any other ways the attacker can still link the messages from a particular node to hamper the nodes privacy. Finally after analyzing the results from the research, we propose a solution to include a new module in the PRESERVE architecture called Identifier Change Management (IDCM) module to improve the anonymity of the user participating in the vehicular communication.

No description available.

Film thickness, free carrier concentration and free carrier mobility are critical figures of merit for silicon carbide epitaxial growth. Room temperature Fourier Transform Infrared (FTIR) reflection spectroscopy can estimate these parameters non-destructively and is capable of high-resolution wafer mapping. Commercially available equipment has greatly simplified the application of this technique by coupling a high performance automated spectrometer with model-based data analysis and interpretation based on the personal computer. While powerful numerical techniques run fast and efficient on modern computers, it is essential that low-order, well-conditioned models are needed. The observed reflectance spectrum is the result of reflection and refraction of light at different interfaces due to constructive and destructive interference. The estimation of film thickness and free carrier concentration for single epitaxial layers has been improved by studying the Longitudinal Optical Phonon Plasmon (LPP) coupled modes. However, the addition of multiple layers introduces many degrees of freedom, which complicates parameter extraction. The multiple epitaxial layer stacks studied were intended for Metal Semiconductor Field Effect Transistor (MESFET?s) on both conducting and semi-insulating substrates. The thickness estimation of the n-channel in the MESFET stack on semi-insulating substrate is improved by preconditioning the curve fit for plasma frequency obtained from doping estimation from capacitance voltage profiling or by observing an LPP- peak.

No description available.