Can a Leopard Change His Spots?: Child Custody and Batterer’s Intervention

Enabling multiple base stations to utilize the spatial dimension in a coordinated manner has been shown to be a fruitful technique for improving the spectral efficiency in wireless interference networks. This thesis considers multicell systems where base stations and mobile stations are equipped with multiple antennas. The base stations coordinate their spatial precoding, but individually serve their mobile stations with data. For such coordinated precoding systems, interference alignment (IA) is a useful theoretical tool, due to its ability to serve the maximum number of interference-free data streams. Three topics related to interference alignment and coordinated precoding are studied. First, the feasibility of IA over a joint space-frequency signal space is studied. A necessary condition for space-frequency IA feasibility is derived, and the possible gain over space-only IA is analyzed. An upper bound on the degree of freedom gain is shown to increase in the number of subcarriers, but decrease in the number of antennas. Numerical studies, using synthetically generated channels and real-world channels obtained from indoors and outdoors channel measurements, are used for sum rate performance evaluation. The results show that although a degree of freedom gain is noticeable due to the space-frequency precoding, the sum rate of the system is mainly improved due to a power gain. Second, distributed channel state information (CSI) acquisition techniques are proposed, which provide estimates of the information necessary to perform distributed coordinated precoding. The methods are based on pilot-assisted channel estimation in the uplink and downlink, and correspond to different tradeoffs between feedback and signaling, backhaul use, and computational complexity. Naively applying the existing WMMSE algorithm for distributed coordinated precoding together with the estimated CSI however results in poor performance. A robustification of the algorithm is therefore proposed, relying on the well known diagonal loading technique. An inherent property of the WMMSE solutions is derived and, when enforced onto solutions with imperfect CSI, results in diagonally loaded receive filters. Numerical simulations show the effectiveness of the proposed robustification. Further, the proposed robustified and distributed WMMSE algorithm performs well compared to existing state-of-the-art robust WMMSE algorithms. In contrast to our approach, the existing methods however rely on centralized CSI acquisition. Third, coordinated precoding systems with hardware impairments are studied. Assuming that impairment compensation techniques have been applied, a model is used to describe the aggregate effect of the residual hardware impairments. An iterative resource allocation method accounting for the residual hardware impairments is derived, based on an existing resource allocation framework. Numerical simulations show that the proposed method outperforms all benchmarks. In particular, the gain over impairments-aware time-division multiple access is substantial.Genom att låta flera radiobasstationer samarbeta är det möjligt att förbättra spektraleffektiviteten i trådlösa interferensnätverk. Fokus i denna licentiatavhandling ligger på multicellnätverk där både radiobasstationer och mobilenheter har flera antenner. Radiobasstationerna väljer sina spatiella förkodare gemensamt, men skickar data individuellt till sina respektive mobilenheter. För sådana system med koordinerad förkodning ('coordinated precoding') är interferensupprätning ('interference alignment') ett användbart teoretiskt verktyg, eftersom det möjliggör överföring av maximalt antal dataströmmar i nätverket. I avhandlingen studeras tre aspekter av interferensupprätning och koordinerad förkodning. Först undersöks interferensupprätning när signalrummet består av en kombination av rymd- och frekvensdimensioner. Ett nödvändigt villkor härleds för existensen av rymd/frekvens-interferensupprätning, och prestandavinsten analyseras i jämförelse med system där enbart rymddimensionerna används för interferensupprätning. Det föreslagna systemet utvärderas med hjälp av numeriska simuleringar och uppmätta inomhus- och utomhuskanaler. Resultaten visar att rymd/frekvens-interferensupprätning ger upphov till ett ökat antal frihetsgrader, men att summadatatakten främst förbättras tack vare en upplevd effektförstärkning. Därefter undersöks tekniker för skattning av den nödvändiga kanalkännedom som krävs för att genomföra koordinerad förkodning. Det finns flera sätt att erhålla den nödvändiga informationen, t.ex. genom olika kombinationer av kanalskattning, feedback, signalering och användning av backhaulnätverk. Speciellt söks distribuerade metoder, eftersom dessa är fördelaktiga vid praktisk implementering. Tre metoder för skattning av kanalkännedom föreslås. Dessa motsvarar olika avvägningar mellan kanalskattning och signalering, och en av metoderna är helt distribuerad. När den skattade informationen används med en existerande algoritm för koordinerad förkodning blir prestandan undermålig. Därför föreslås två förändringar av algoritmen, vilka leder till mer robusta prestanda. Förändringarna bygger på den välkända diagonal loading-tekniken. Utvärdering av det föreslagna systemet, som består av distribuerad erhållning av kanalkännedom samt den förbättrade algoritmen för koordinerad förkodning, genomförs med numerisk simulering. Resulterande prestanda är i nivå med ett tidigare föreslaget system, som dock kräver centraliserad tillgång till kanalskattningarna, till skillnad från vår nya lösning. Slutligen studeras ett system med koordinerad förkodning och icke-perfekt radiohårdvara. En modell för distortionsbruset orsakad av bristerna i radiohårdvaran används, och en iterativ resurstilldelningsteknik föreslås baserad på ett existerande ramverk. Den föreslagna algoritmen kan implementeras distribuerat över mobilenheterna, men kan i allmänhet inte implementeras distribuerat över radiobasstationerna. Den föreslagna algoritmen utvärderas med numeriska simuleringar, och resultaten visar att prestanda är bättre än alla referensmetoder. Detta visar betydelsen av att hantera bristerna i radiohårdvaran i resurstilldelningen. Sammantaget visar avhandlingen på möjligheterna att öka spektraleffektiviteten i framtida multicellnätverk med hjälp av koordinerad förkodning.QC 20140512</p

Solar cell system having alternating current output

A monolithic multijunction solar cell was modified by fabricating an integrated circuit inverter on the back of the cell to produce a device capable of generating an alternating current output. In another embodiment, integrated curcuit power conditioning electronics was incorporated in a module containing a solar cell power supply

Electron beam recrystallization of amorphous semiconductor materials

Nucleation and growth of crystalline films of silicon, germanium, and cadmium sulfide on substrates of plastic and glass were investigated. Amorphous films of germanium, silicon, and cadmium sulfide on amorphous substrates of glass and plastic were converted to the crystalline condition by electron bombardment

Method for producing solar energy panels by automation

A solar cell panel was fabricated by photoetching a pattern of collector grid systems with appropriate interconnections and bus bar tabs into a glass or plastic sheet. These regions were then filled with a first, thin conductive metal film followed by a layer of a mixed metal oxide, such as InAsO or InSnO. The multiplicity of solar cells were bonded between the protective sheet at the sites of the collector grid systems and a back electrode substrate by conductive metal filled epoxy to complete the fabrication of an integrated solar panel

Solar cell collector and method for producing same

A transparent, conductive collector layer containing conductive metal channels is formed as a layer on a photovoltaic substrate by coating a photovoltaic substract with a conductive mixed metal layer. A heat sink having portions protruding from one of its surfaces is attached. These protruding portions define a continuous pattern in combination with recessed regions among them such that they are in contact with the conductive layer of the photovoltaic substrate. Heating the substrate while simultaneously oxidizing the portions of the conductive layer exposed to a gaseous oxidizing substance forced into the recessed regions of the heat sink, creates a transparent metal oxide layer on the substrate. A continous pattern of highly conductive metal channels is contained in the metal oxide layer

Cheese Makers are Always Women: Gendered Representations of Farm Life in the Agricultural Press

Drawing upon the 'Farmlife' pages of Farmer's Weekly, the most significant farming publication in the UK, this paper assesses the ways in which gender identities in farming are represented by its text and images. Lead articles from 1976 and 1996 issues of Farmlife are taken as the research focus to determine how representations have altered in line with restructuring of the agricultural industry. Reference is made to Connell's (1987) notions of hegemonic masculinity and emphasised femininity to inform the analysis about the ways in which these gender identities are (re)produced through the British farming media. A simple typology is derived from the articles which assists in revealing a remarkable degree of consistency in the portrayal of gender identities over time. The findings augment evidence from international research suggesting that dominant gender identities within agriculture are being perpetuated through the farming media. The implications of this are highlighted and suggestions made for research with the consumers of these media products

Solar cell power scanner

System locates high- and low-output regions in cadmium sulfide thin film photovoltaic cells. High resolution photograph shows conversion efficiency of each scanned area. X-Y recorder fed by amplified signal from solar cell also produces power contour map. Photo and map reveal high- and low-conversion-efficiency regions