<p>Metal contaminated stormwater, i.e. surface runoff in urban areas, can be treated in percolation systems, ponds, or wetlands to prevent the release of metals into receiving waters. Plants in such systems can, for example, attenuate water flow, bind sediment, and directly accumulate metals. By these actions plants affect metal mobility. This study aimed to examine the accumulation of Zn, Cu, Cd, and Pb in roots and shoots of plant species common in stormwater areas. Furthermore, submersed plants were used to examine the fate of metals: uptake, translocation, and leakage. Factors known to influence metal accumulation, such as metal ion competition, water salinity, and temperature, were also examined. The following plant species were collected in the field: terrestrial plants – <i>Impatiens parviflora</i>, <i>Filipendula ulmaria</i>, and <i>Urtica dioica</i>; emergent plants –<i> Alisma-plantago aquatica</i>, <i>Juncus effusus</i>, <i>Lythrum salicaria</i>, <i>Sagittaria sagittifolia</i>, and <i>Phalaris arundinacea</i>; free-floating plants – <i>Lemna gibba</i> and <i>Lemna minor</i>; and submersed plants – <i>Elodea canadensis</i> and <i>Potamogeton natans</i>. Furthermore, the two submersed plants, <i>E. canadensis</i> and <i>P. natans</i>, were used in climate chamber experiments to study the fate of the metals in the plant–water system.</p><p>Emergent and terrestrial plant species accumulated high concentrations of metals in their roots under natural conditions but much less so in their shoots, and the accumulation increased further with increased external concentration. The submersed and free-floating species accumulated high levels of metals in both their roots and shoots. Metals accumulated in the shoots of <i>E. canadensis</i> and <i>P. natans</i> derived mostly from direct metal uptake from the water column.</p><p>The accumulation of Zn, Cu, Cd, and Pb in submersed species was in general high, the highest concentrations being measured in the roots, followed by the leaves and stems, <i>E. canadensis</i> having higher accumulation capacity than <i>P. natans</i>. In <i>E. canadensis</i> the Cd uptake was passive, and the accumulation in dead plants exceeded the of living with time. The capacity to quickly accumulate Cd in the apoplast decreased with successive treatments. Some of the Cd accumulated was readily available for leakage. In <i>P. natans,</i> the presence of mixtures of metal ions, common in stormwater, did not alter the accumulation of the individual metals compared to when presented separately. It is therefore, proposed that the site of uptake is specific for each metal ion. In addition cell wall-bound fraction increased with increasing external concentration. Further, decreasing the temperature from 20ºC to 5ºC and increasing the salinity from 0‰ to 5‰ S reduced Zn and Cd uptake by a factor of two.</p><p>In <i>P. natans</i> the metals were not translocated within the plant, while in<i> E. canadensis </i>Cd moved between roots and shoots. Thus,<i> E. canadensis</i> as opposed to <i>P. natans</i> may increase the dispersion of metals from sediment via acropetal translocation. The low basipetal translocation implies that neither <i>E. canadensis</i> nor <i>P. natans</i> will directly mediate the immobilisation of metal to the sediment via translocation.</p><p>To conclude, emergent and terrestrial plant species seem to enhance metal stabilization in the soil/sediment. The submersed plants, when present, slightly increase the retention of metals via shoot accumulation.</p>

<p>This thesis work has been performed at the department of diagnosis and dependability at Volvo Car Company, Torslanda. The background of this project is based on interest in ascertaining how different factors possibly can affect a diagnosis method, which has been developed to find leaks in the fuel tank and evaporation system. According to the OBD II requirements leaks with an orifice diameter larger or equal to 0,5 mm, must be detected. The idea of the diagnosis method is to create an over pressure in the system with an air-pump. The current through the pump is measured and correlates to the power consumed by the pump. As the power is a function of the pressure difference over the pump, the pump current correlates to the pressure in the tank. Thus, the pump current can be used as a measure of the impenetrability. Changes in the system pressure, not caused by the pump, are accordingly disturbances to the method. </p><p>The object of this work was to develop mathematical models, describing the lapse where the system is pressurized by the pump under the influence of different physical factors. The model is for instance considering variations in temperature and height, flow resistance in lines and valves, component characteristics, fuel evaporation, leaks etc. Furthermore the pump current is treated by the diagnosis evaluation algorithm with purpose to judge whether there is a leak in the system. </p><p>The model has been implemented in Matlab/Simulink and it can consequently be used in dynamic simulations according to the over pressure leakage detection concept. Numerical experiments can be done in purpose to examine how changes in environmental conditions or component characteristics will affect the diagnosis method. Good agreement has been found between measurements and simulated results. The diagnosis function produces correct decisions under different conditions with disparity in leak sizes, additionally confirming the reliability of the model.</p>

<p>The impressive evolution of modern high-performance microprocessors have resulted in chips with over one billion transistors as well as multi-GHz clock frequencies. As the silicon integrated circuit industry moves further into the nanometer regime, three of the main challenges to overcome in order for continuing CMOS technology scaling are; growing standby power dissipation, increasing variations in process parameters, and increasing power dissipation due to growing clock load and circuit complexity. This thesis addresses all three of these future scaling challenges with the overall focus on reducing the total clock-power for low-power, multi-GHz VLSI circuits.</p><p>Power-dissipation related to the clock generation and distribution is identified as the dominating contributor of the total active power dissipation. This makes novel power reduction techniques crucial in future VLSI design. This thesis describes a new energy-recovering clocking technique aimed at reducing the total chip clock-power. The proposed technique consumes 2.3x lower clock-power compared to conventional clocking at a clock frequency of 1.56 GHz.</p><p>Apart from increasing power dissipation due to leakage also the robustness constraints for circuits are impacted by the increasing leakage. To improve the leakage robustness for sub-90 nm low clock load dynamic flip-flops a novel keeper technique is proposed. The proposed keeper utilizes a scalable and simple leakage compensation technique. During any low frequency operation, the flip-flop is configured as a static flip-flop with increased functional robustness.</p><p>In order to compensate the impact of the increasingly large process variations on latches and flip-flops, a reconfigurable keeper technique is presented in this thesis. In contrast to the traditional design for worst-case process corners, a variable keeper circuit is utilized. The proposed reconfigurable keeper preserves the robustness of storage nodes across the process corners without degrading the overall chip performance.</p> / Report code: LiU-TEK-LIC-2006:21.

This thesis presents numerical predictions for the leakage and direct stiffness coefficients of pocket damper seals. Modifications made to earlier flow-prediction models are discussed. Leakage and static pressure measurements on straight-through and diverging configurations of eight-bladed and twelve-bladed seals were used for code validation and for calculation of seal discharge coefficients. Higher than expected leakage rates were measured in the case of the twelve-bladed seal, while the leakage rates for the eight-bladed seals were predicted reasonably accurately. Results are presented for shake tests conducted on the seals at pressures of up to 1000 Psi (6.90 MPa). Test variables included pressure drop across the seals and rotor speed. The experimentally obtained stiffness coefficients are compared to results of a rotordynamic damper seal code, which uses the corrected mass flow-rate calculation method. Results show that the code under-predicts the magnitude of the seal's stiffness for most test cases. However, general trends in the frequency dependency of the direct stiffness are more accurately predicted. The expectation of high values of negative stiffness in diverging seals is confirmed by the results, but the frequency at which the sign of the stiffness becomes positive is considerably lower than is predicted. In addition to presenting high-pressure test data, this thesis also attempts to provide some insight into how seal parameters can be modified to obtain desired changes in seal stiffness.

Cosmic reionization was most likely initiated by star forming dwarf galaxies. Little is known about the physical mechanisms allowing ionizing Lyman continuum (LyC) photons to escape from galaxies, but to learn more we can study local galaxies in detail. Until now, there has however only been one claim of a local LyC leaking galaxy, the disputed case of Haro 11. The lack of local detections could in part be a combined effect of technical problems and search strategies. Re-examining the FUSE (Far Ultraviolet Spectroscopic Explorer) data of Haro 11 led us to develop a new model for the spectral reduction, by which we could confirm an escape fraction of LyC photons (fesc) of 3.3±0.7%. In addition, eight more galaxies from the FUSE archive were examined leading to a new detection, Tol 1247-232, with fesc = 2.4±0.5%. The low value derived from the stacked spectrum of the whole sample, fesc = 1.4±0.4%, could be an indication of an evolving fesc scenario and/or an effect of probing the wrong targets. Local LyC candidates are normally selected among starburst galaxies with high equivalent widths in Hα. This can however give preference to ionization bounded H II regions with low escape fractions. In an attempt to overcome this selection bias, we developed a novel method to select LyC leaking galaxies. The selection is based on a blue continuum and weak emission lines, properties that in combination can be explained only by models with very high fesc. Using these criteria, we selected a sample of leaking candidates at z≈0.03 to be observed in Hα and Johnson B filters. The sample galaxies have properties that strongly favour leakage. Among these are clear signs of mergers and interaction with neighbouring galaxies, off-centre major star forming regions and spectral properties indicating previous starburst activity. The Lyman-alpha (Lyα) line is often used as a tracer for the distant galaxies believed to have reionized the universe. Here, for the first time local face-on spiral galaxies are studied in Lyα imaging. All three galaxies are emitting Lyα photons in the polar direction far out in the spiral arms, in clear contrast to previously studied irregular galaxies where strong emission is seen from the nuclei. If the small sample studied here is representative, it will have implications for detecting Lyα galaxies at high redshifts as it would depend strongly on the viewing angle.

Metal contaminated stormwater, i.e. surface runoff in urban areas, can be treated in percolation systems, ponds, or wetlands to prevent the release of metals into receiving waters. Plants in such systems can, for example, attenuate water flow, bind sediment, and directly accumulate metals. By these actions plants affect metal mobility. This study aimed to examine the accumulation of Zn, Cu, Cd, and Pb in roots and shoots of plant species common in stormwater areas. Furthermore, submersed plants were used to examine the fate of metals: uptake, translocation, and leakage. Factors known to influence metal accumulation, such as metal ion competition, water salinity, and temperature, were also examined. The following plant species were collected in the field: terrestrial plants – Impatiens parviflora, Filipendula ulmaria, and Urtica dioica; emergent plants – Alisma-plantago aquatica, Juncus effusus, Lythrum salicaria, Sagittaria sagittifolia, and Phalaris arundinacea; free-floating plants – Lemna gibba and Lemna minor; and submersed plants – Elodea canadensis and Potamogeton natans. Furthermore, the two submersed plants, E. canadensis and P. natans, were used in climate chamber experiments to study the fate of the metals in the plant–water system. Emergent and terrestrial plant species accumulated high concentrations of metals in their roots under natural conditions but much less so in their shoots, and the accumulation increased further with increased external concentration. The submersed and free-floating species accumulated high levels of metals in both their roots and shoots. Metals accumulated in the shoots of E. canadensis and P. natans derived mostly from direct metal uptake from the water column. The accumulation of Zn, Cu, Cd, and Pb in submersed species was in general high, the highest concentrations being measured in the roots, followed by the leaves and stems, E. canadensis having higher accumulation capacity than P. natans. In E. canadensis the Cd uptake was passive, and the accumulation in dead plants exceeded the of living with time. The capacity to quickly accumulate Cd in the apoplast decreased with successive treatments. Some of the Cd accumulated was readily available for leakage. In P. natans, the presence of mixtures of metal ions, common in stormwater, did not alter the accumulation of the individual metals compared to when presented separately. It is therefore, proposed that the site of uptake is specific for each metal ion. In addition cell wall-bound fraction increased with increasing external concentration. Further, decreasing the temperature from 20ºC to 5ºC and increasing the salinity from 0‰ to 5‰ S reduced Zn and Cd uptake by a factor of two. In P. natans the metals were not translocated within the plant, while in E. canadensis Cd moved between roots and shoots. Thus, E. canadensis as opposed to P. natans may increase the dispersion of metals from sediment via acropetal translocation. The low basipetal translocation implies that neither E. canadensis nor P. natans will directly mediate the immobilisation of metal to the sediment via translocation. To conclude, emergent and terrestrial plant species seem to enhance metal stabilization in the soil/sediment. The submersed plants, when present, slightly increase the retention of metals via shoot accumulation.

Introduction: Haemodialysis (HD) is a treatment in which blood from the patient is lead through a tubing system into a dialysis device in a extracorporeal circuit. This circuit contains semipermeable membranes (dialyzer). Blood with uraemic toxins flows on one side, and a salt solution flows on the other side. The salt solution flushes away waste products that have passed the membrane by diffusion or convection through small pores. From there the blood returns to the patient through a tubing system that contains an air-trap and a sensor to avoid air contamination in the blood. Besides air contamination, this treatment is burdened with safety problems such as biocompatibility, electrical safety and mechanical safety. The aim of this thesis was to investigate the safety issues in haemodialysis devices regarding leakage current and air contamination during standard procedures and simulated fault conditions. Does the dialysis device constitute a risk for the patient? Methods: To determine the extent of leakage current in HD machines, measurements at the filter-coupling site were performed in vitro according to the safety standard, IEC 601-1, in 5 types of dialysis machines. To determine, in vitro, to what extent blood and priming fluid allowed leakage current to pass to the patient, leakage current were also measured in the blood lines. The blood line was filled with blood from donors or priming fluid in eight different runs. To determine if leakage current could influence biocompatibility, a Fresenius 2008C dialysis machine and 8 hemophan dialyzers were used. Blood lines contained about 400 ml heparinized blood from each of 8 different donors (in vitro). C3d was measured, in vitro, before start of a simulated dialysis and at 15, 30, 45 and 60 min. during standard dialysis procedure. Then 1.5 mA current was switched on and additional samples were drawn at 75 and 90 min. Some patients need a central dialysis catheter (CDC) for access, placed close to or within the heart. To analyze if leakage current during standard HD would influence the ECG, patients with CDC or with AV-fistula as access were investigated. To analyse if air contamination could occur without activating security alarms in the dialysis device, various modes of in vitro dialysis settings were studied, some using a dextran solution to mimic blood viscosity. Besides visual inspection an ultrasound detector for microemboli and microbubbles was also used. Results: The data showed leakage current at the filter coupling site that was significantly higher for some devices than for others. The leakage current could pass through blood and priming fluid. It exceeded the cardiac floating (CF)-safety limit (&lt;50μA) at the top of the CDC using the test mains on applied part for saline (median 1008μA), for blood (median 610μA) and for a single fault condition using saline (median 68 μA) or blood (47 μA). The leakage current experiments showed that complement activation worsened as the leakage current increased. During standard dialysis arrhythmia could occur. Microbubbles were visible at the bottom of the air-trap and bubbles could pass the air-trap towards the venous line without triggering the alarm. During recirculation, several ml of air could be collected in an intermediate bag after the venous line. Ultrasound showed the presence of bubbles of sizes 2.5-50 μm as well as more than 50 μm silently passing to the venous line in all runs performed. In conclusion, the data showed that a leakage current in HD devices can be high enough to be a safety risk for the patient. This risk is greater if a single fault arises in the dialysis machine or another device connected to the same patient, or during mains contact to the patient. Then the current flow may be high enough to cause arrhythmia for the patient, especially when using a CDC. There is also reason for concern that micro bubble transmission may occur without inducing an alarm. These factors need to be looked over to improve safety regulations and optimize HD treatment and service schedules.

No description available.

En esta tesis se han desarrollado modelos compactos de corriente de fuga por túnel de puerta en SOI MOSFET (de simple y doble puerta) avanzados basados en una aproximación WKB de la probabilidad de túnel. Se han estudiado los materiales dieléctricos high-k más prometedores para los diferentes requisitos de nodos tecnológicos de acuerdo ala hoja de ruta ITRS de miniaturización de dispositivos electrónicos. Hemos presentado un modelo compacto de particionamiento de la corriente de fuga de puerta para un MOSFET nanométrico de doble puerta (DG MOSFET), utilizando modelos analíticos de la corriente de fuga por el túnel directo de puerta. Se desarrollaron también Los modelos analíticos dependientes de la temperatura de la corriente de túnel en la región de inversión y de la corriente túnel asistido por trampas en régimen subumbral. Finalmente, se desarrolló una técnica de extracción automática de parámetros de nuestro modelo compacto en DG MOSFET incluyendo efectos de canal corto. La corriente de la puerta por túnel directo y asistido por trampas modelada mediante los parámetros extraídos se verificó exitosamente mediante comparación con medidas experimentales.

Over the last 10 years, digital subthreshold logic circuits have been developed for applications in the ultra-low power design domain, where performance is not the priority. Recently, devices optimized for subthreshold operation have been introduced as potential construction blocks. However, for these devices, a strong sensitivity to process variations is expected due to the exponential relationship of the subthreshold drive current and the threshold voltage. In this thesis, a yield optimization technique is proposed to suppress the variability of a device optimized for subthreshold operation. The goal of this technique is to construct and inscribe a maximum yield cube in the 3-D feasible region composed of oxide thickness, gate length, and channel doping concentration. The center of this cube is chosen as the maximum yield design point with the highest immunity against variations. By using the technique, a transistor is optimized for subthreshold operation in terms of the desired total leakage current and intrinsic delay bounds. To develop the concept of the technique, sample devices are designed for 90nm and 65nm technologies. Monte Carlo simulations verify the accuracy of the technique for meeting power and delay constraints under technology-specific variances of the design parameters of the device.