No / A printed crescent-shaped monopole MIMO antenna is presented for handheld wireless communication devices. The mutual coupling between the two antenna elements can be minimised by implementing a I-shaped common radiator. Both the simulated and measured results agree that the antenna covers the operating frequency band from 1.6 to 2.8 GHz with the return loss and isolation better than 10 dB and 14 dB respectively. To further verifying the MIMO characteristic including far-field, gain, radiation efficiency, channel capacity loss and envelope correlation, the results confirm that the antenna can operate effectively in a rich multipath environment.

The thesis is focused on remitting lead-acid segments of partial charge mode which simulates the conditions in HEV. The experimental cells were submitted to different pressures on the electrode system. The main aim of the thesis was to minimize the irreversible sulphating of the negative electrodes, which are in the PSoC regime limiting in the overall life of lead-acid accumulators. All cells were submitted to measurement of the negative electrode potentials, resistance of active materials, contact resistance of the grid – the active material and measurements of pressure changes during three PSoC cycles.

京都大学 / 新制・課程博士 / 博士(情報学) / 甲第23316号 / 情博第752号 / 新制||情||128(附属図書館) / 京都大学大学院情報学研究科社会情報学専攻 / (主査)教授 多々納 裕一, 教授 畑山 満則, 准教授 大西 正光 / 学位規則第4条第1項該当 / Doctor of Informatics / Kyoto University / DGAM

Lead-acid accumulators are the oldest and most common type of secondary cells. There are still some problems to solve. Grid corrosion in sulphuric acid is one of them, which reduced lifetime of lead-acid accumulators. The first part of work is focusing on a general theoretic description of lead – acid accumulators. Following is a description of the workstation and method of measuring. The final part of the text is measuring on an experimental cell.

Main goal of the diploma thesis is to examine lead-acid accumulator and to study cycling modes in different setups. Theoretical part describes history, types of maintenance-free batteries, degradation mechanisms and possibilities to remove them. Practical part involves the production of electrodes and experimental cell, composition of active mass and measurement of internal resistance. Different configurations for deep cycling are researched as well. The results of the work are summarized and commented at the conclusion of the thesis.

The rapidly growing demand for UWB as high data rates wireless communications technology, since the Federal Communications Commission (FCC) allocated the bandwidth of UWB from 3.1GHz to 10.6 GHz. Antenna also plays an essential role in UWB system. However, there are some difficulties in designing UWB antenna as compared to narrowband antenna. The primary requirement of UWB antennas is be able to operate over frequencies released by the FCC. Moreover, the satisfaction of radiation properties and good time domain performance over the entire frequency range are also necessary. In this thesis, designing and analysing printed crescent shape monopole antenna, Planar Inverted F-L Antenna (PIFLA) and Planar Inverted FF Antenna (PIFFA) are focused. A Planar Inverted FF Antenna (PIFFA) can be created to reduce the potential for interference between a UWB system and other communications protocols by using spiral slot. The antennas exhibits broadside directional pattern. The performances such as return loss, radiation pattern and current distribution of the UWB antennas are extensively investigated and carried out. All the results have been demonstrated using simulation and experimentally whereby all results satisfy the performance under - 10dB point in the bandwidth of UWB. In addition the miniaturization of MIMO/diversity Planar Inverted-F antenna (PIFA) which is suitable for pattern diversity in UWB applications is presented. This antenna assembly is formed by two identical PIFAs, a T-shaped decoupling structure which connects the two PIFAs and a finite ground plane with a total compact envelope dimension of 50 x 90 x 7.5mm³. The radiation performance of the proposed MIMO antenna was quite encouraging and provided an acceptable agreement between the computed and measured envelope correlation coefficient and channel capacity loss.

Invånarantalet i Stockholm ökar och därmed också efterfrågan på dricksvatten. Stockholm Vatten VA AB fastslog i sin senaste prognos att kapaciteten hos deras vattenverk i Norsborg och på Lovö kommer att vara otillräcklig inom femton år och därmed måste ökas. Båda vattenverken tar vatten från Mälaren och renar detta genom flockning, sedimentering, snabbfiltrering, långsamfiltrering, UV-bestrålning samt tillsats av kloramin. Baserat på de senaste årens drifterfarenheter har långsamfiltrens kapacitet skrivits ned och är ett begränsande produktionssteg på båda verken. Detta examensarbete syftade till att fastställa orsakerna till kapacitetsminskningen och föreslå åtgärder. Undersökningen begränsades till Lovö vattenverk, men resultaten anses relevanta även för Norsborgs vattenverk.   De senaste åren har långsamsandfiltrens drifttid mellan rensningar minskat och tryckfallet i genomsnitt ökat. Här sågs att tryckfallet direkt efter rensning var högre i den undersökta periodens slut än under periodens början. Då filtrens belastning undersöktes konstaterades att filtreringshastigheten inte ökat och vattenkvaliteten inte försämrats. Utifrån detta drogs slutsatsen att kapacitetsminskningen inte berodde på ökad belastning.    Med hjälp av rör satta i filtersanden kunde tryckfallets fördelning över filterbäddens djup undersökas. I två av de undersökta filtren sågs ett kraftigt tryckfall i filtrens undre del. Då provgropar grävdes i filtren sågs ett tydligt gråaktigt lager vid den nivå där tryckfallet skett. Analyser av sandprover från filtren tydde på att en ackumulering av finkorniga sandpartiklar och organiskt material samt en lågporositet, gav det gråa lagret en låg mättad hydraulisk konduktivitet. Ackumuleringen av finkorniga sandpartiklar skulle kunna bero på att finkornigt material lyfts från filtrens hörn, där sandlagret är tunnare, och fördelas över resterande delar av filtret vid återfyllnad efter rensning.   Mätningar av porositet visade att filterbädden kompakteras då det belastas av de fordon som används vid rensning. Resultaten tyder dock på att packningens utbredning och omfattning är sådan att den inte har någon större effekt på tryckfallet i filtret. / Stockholm is growing and with it the demand for drinking water. To meet the demand the capacity of the two water treatment plants in Norsborg and at Lovö must be increased. Both plants use water from the lake Mälaren which is treated using flocculation, sedimentation, rapid filtration, slow sand filtration, UV-light and the addition of chloramine. The estimated capacity of the slow sand filters has decreased at both plants during the last few years and is limiting the total production capacity. This study aims to find the cause of the capacity decrease and make suggestions for how the capacity could be increased. Only the water treatment plant at Lovö was examined in this study, but the results are considered to be relevant for the water treatment plant in Norsborg as well.   During recent years the runtime of the filters has been decreasing and the overall loss of hydraulic head has increased. In several filters it was noted that the hydraulic head loss after filter cleaning had increased over time. Filter load was examined during the period in which the loss in capacity took place. Neither had the filtration rate increased nor had the water quality decreased. A higher load could therefore be ruled out as the source of the capacity loss.   Hydraulic head loss distribution over the depth of the filter beds was examined using steel pipes placed in the filter bed at different depths. In two filters a large hydraulic head loss was found at a narrow section in the bottom of the filters. Holes were dug in the filter beds, from which a distinct grey layer could be observed. Sand analyses showed that an accumulation of fine sand particles and organic matter combined with a low porosity could have been what caused the large hydraulic head loss in the layer. This material could have originated from the corners of the filters. During filter refill, fine material was observed being suspended from the corners and spread across the filter.   Measurements of sand porosity suggested that the filter bed is compacted by the machines used to clean the filters. This however seemed to have a negligible effect on the hydraulic head loss in the filters.

The task of research work is to study new mechanisms and to minimize disturbance of lead batteries for hybrid electric vehicles. Those arising under the PSoC (Partial State of Charge) and is linked to irreversible sulphation mainly negative electrodes. As one solution to prevent sulphation of the negative electrode appears to be the active ingredients in a negative matter. In the investigated electrodes is verified the influence of carbon, titanium dioxide and silica on the grain size of the order of nanometers.

This thesis describes the results of two successive experiments. The first was focused on the influence of impurities in the active mass of negative electrode in PSoC (Partial State of Charge) mode, which simulates the conditions occurring in HEV (hybrid electric vehicle). In the second experiment, cells with the same additives were exposed to optimum downforce 4N/cm2, by which we wanted to prove the influence of pressure on life of VRLA (Valve Regulated Lead Acid) cells working in operating HEV conditions.

Lead-acid batteries of hybrid electric vehicles (HEV) are functioning in PSoC regime (Partial State of Charge). In PSoC regime new fail mechanisms occur. These mechanisms usually lead to nonreversible sulphation of negative electrodes. Main aim of this research is to avoid negative electrode sulphation and to improve lifetime of lead-acid accumulators used in HEV.