Modeling poly-Si/SiOx/c-Si junctions for solar cells

Es wird ein halbanalytisches Modell zur Berechnung der elektrischen Eigenschaften von poly-Si/SiOx/c-Si Schichtstapeln zur Kontaktierung von Siliziumsolarzellen vorgestellt. Das Modell berechnet Majoritäten- und Minoritätenströme anhand der strukturellen Schichteigenschaften in Abhängigkeit der angelegten Spannung, der Beleuchtung und der Temperatur. Das Modell wird mit finite-Elemente-Simulationen verglichen und zur Bestimmung der Störstellendichte an der SiOx/c-Si Grenzfläche von verschiedenen Probentypen verwendet

Energikjedeanalyse av ammoniakk som drivstoff i bulkskip

Sjøfarten i dag står for rundt 3 prosent av totale klimagassutslipp i verden. Gjennom Parisavtalen har Norge forpliktet seg til å følge en nasjonal plan for hvordan vi som nasjon skal kutte klimagassutslippene. I dag går de fleste sjøfartøy enten på tung fyringsolje eller diesel. For å redusere klimagassutslippene er det avgjørende å legge alternative løsninger for drivstoff på bordet. Ammoniakk og hydrogen brukt som drivstoff er utgangspunktet karbonfrie fordi de ikke slipper ut CO2-e under bruk. Av den grunn blir disse to drivstoffene sett på som to løsninger til å redusere klimagassutslipp sett at produksjonen av drivstoffene baserer seg på fornybare energikilder. Videre viser prognoser at ammoniakk blir sett på som fremtidens drivstoff innenfor skipsfart. Grunnen er at ammoniakk har høyere energitetthet enn hydrogen, og er derfor lettere å lagre samt transportere enn hydrogen når det er flytende. I tillegg kan ammoniakk bli brukt i en forbrenningsmotor og kan bidra til å redusere behovet for å bytte ut hele fartøyet. Problemstillingen i denne oppgaven lyder følgende: Kan ammoniakk som drivstoff i skip bidra til å redusere klimagassutslipp? Hvilken produksjonsmetode av ammoniakk fører til minst klimagassutslipp? Er ammoniakk som drivstoff et bedre alternativ enn hydrogen sett i lyset av klimagassutslipp? Vil ammoniakk slippe ut mindre klimagasser i forhold til diesel? For å svare på problemstillingen er energikjedeanalyse benyttet. Dette er en metode som gjør det mulig å beregne det totale energiforbruket gjennom ulike delprosesser til en energikjede. På denne måten er det mulig å finne det totale energibruket fra energikjeden fra eksempelvis utvinning av energikilde til bruk i skip. Metodetilnærmingen for det totale energibruket kalles også WTP, som står for well-to-propeller. Ved å beregne energibruken kan man videre beregne klimagassutslippet for energikjedene, som er hovedfokuset i denne oppgaven. Videre er det syv forskjellige energikjeder som blir analysert. Tre av energikjedene benytter seg av ammoniakk som drivstoff i en forbrenningsmotor, tre benytter seg av hydrogen som drivstoff i en brenselcelle og en benytter seg av diesel i en forbrenningsmotor. To av både ammoniakk, - og hydrogenkjedene baserer seg på vannelektrolyse som benytter seg av strøm fra enten vindkraft eller kullkraft. I tillegg er det en ammoniakk, - og hydrogenkjede som tar utgangspunkt i dampreformering av naturgass. De to sistnevnte energikjedene har i tillegg tilført energi i form av norsk strømmiks. Energikjedene har derfor WTP delt i to, hvor tilført energi heter WTPel. WTPprimær menes med utslippet fra den primære energikilden. På bakgrunn av at det er lite kunnskap om ammoniakk, er drivstofforbruket for alle drivstoffene basert på estimater for samme type bulkskip. Resultatene fra denne oppgaven viser at ammoniakk og hydrogen produsert gjennom vannelektrolyse drevet av vindkraft kan bidra med å redusere klimagassutslippene betraktelig sammenlignet med diesel. Videre er ammoniakk det drivstoffet av de sistnevnte alternativene som har lavest utslipp. Hvis ammoniakk, - og hydrogen produserer gjennom dampreformering av naturgass vil det ikke ha en betydelig reduksjon på ut utslippene i forhold til diesel. På den annen side har både diesel og dampreformering av naturgass betraktelig mindre utslipp enn vannelektrolyse drevet av kullkraft. Dette forteller oss at den tilførte strømmen til vannelektrolyse er avgjørende om produksjonsmetoden til ammoniakk og hydrogen er utslippsvennlig i henhold til utslipp målt i CO2-e.Shipping today accounts for around 3 percent of total greenhouse gas emissions in the world. Through the Paris Agreement, Norway has committed to follow a national plan for how we as a nation will reduce greenhouse gas emissions. Today, most seagoing vessels run on either heavy fuel oil or diesel. In order to reduce greenhouse gas emissions, it is crucial to put alternative solutions for fuel on the table. Ammonia and hydrogen used as fuel are basically carbon-free because they do not emit CO2 while driving. For that reason, these two fuels are seen as two solutions to reduce greenhouse gas emissions given that the production of the fuels is based on renewable energy sources. Furthermore, forecasts show that ammonia is viewed as the fuel of the future within shipping. The reason for this is that ammonia has a higher energy density than hydrogen and is therefore easier to store and transport than hydrogen when it is liquid. In addition, ammonia can be used in an internal combustion engine and can help reduce the need to replace the entire ship. The objectives for this assignment reads as follows: Can ammonia as fuel in ships help reduce greenhouse gas emissions? Which production method of ammonia leads to the least greenhouse gas emissions? Is ammonia as a fuel a better alternative than hydrogen in the light of greenhouse gas emissions? Will ammonia emit less greenhouse gasses compared to diesel? To answer the objectives, energy chain analysis is used. This is a method that makes it possible to calculate the total energy consumption through various sub-processes of an energy chain. In this way, it is possible to find the total energy use from the energy chain from, for example, the extraction of energy sources used in ships. The method approach for the total energy use is also called WTP, which stands for well-to-propeller. By calculating the energy use, one can further calculate the greenhouse gas emissions for the energy chains, which is the main focus of this thesis. In this assignment, there are seven different energy chains considered. Three of the energy chains use ammonia as fuel in an internal combustion engine, three use hydrogen as fuel in a fuel cell and one uses diesel in an internal combustion engine. Two of both the ammonia and hydrogen chains are based on electrolysis of water generated by either wind power or coal power. In addition, there is an ammonia and hydrogen chain based on steam reforming of natural gas. The last two energy chains have also added energy in the form of a Norwegian electricity mix. The energy chains therefore have WTP divided in two, where added energy is called WTPel. WTPprimary means the emissions from the primary energy source. On the basis that there is little knowledge about ammonia, the fuel consumption for all fuels is based on estimates for the same type of bulk carrier. The results from this thesis show that ammonia and hydrogen produced through electrolysis of water powered by wind power can contribute to significantly greenhouse gas emissions reduction compared to diesel. Furthermore, ammonia is the fuel with the lowest emissions. If ammonia and hydrogen are produced through steam reforming of natural gas, there will not be a significant reduction in emissions compared to diesel. On the other hand, both diesel and steam reforming of natural gas have considerably less emissions than water electrolysis powered by coal power. This shows that the current supplied to a water electrolysis is decisive if the production method of ammonia and hydrogen is emission friendly in terms of CO2-e

Contacting a single nanometer-sized pinhole in the interfacial oxide of a poly-silicon on oxide (POLO) solar cell junction

The electrical current through poly-Si on oxide (POLO) solar cells is mediated by tunneling and by nanometer-sized pinholes in the interfacial oxide. To distinguish the two processes, a POLO junction with a measured pinhole density of 1 × 107 cm−2 is contacted by different contact areas ranging from 1 μm2 to 2.5 × 105 μm2, and the temperature-dependent current–voltage curves are measured for the different devices. Model regressions to the measured curves, their temperature dependence, and the quantized value of contact resistances indicate average numbers of pinholes per device corresponding to the expected pinhole density. For the small contacts, the different transport processes can be studied separately, which facilitates further improvements in respect to the present-day POLO junctions. Single-pinhole transport is found for one of the contacts with an area of 1 μm2. Random telegraph noise observed for this device in the current–voltage characteristics shows a high sensitivity to single charges

Institutional Perpetuation of Rape Culture: A Case Study of the University of Colorado Football Rape and Recruiting Scandal

Heterosexual rape among university students is neither new nor uncommon. Research in rape prevention is largely limited to two areas: (1) what women can do to protect themselves from rape, which continues to place the burden of prevention on women; and (2) understanding why men rape. The studies in these fields have added to the body of knowledge surrounding rape on university campuses. The current study takes this information into consideration while using a different lens to examine the University's role, as an institution, in perpetuating rape culture.This study specifically analyzes the rape and recruiting scandal at the University of Colorado at Boulder to better understand how the University, through its reactions to a lawsuit brought against it by three rape victims, perpetuated the rape culture pervading its football community. This ongoing research brings together the fields of institutional theory, theories on sporting masculinities, and feminist rape theories. Additionally, it takes an intersectional feminist approach to examine the dimensions of gender, race, class, and sexuality that are vital to understanding rape, athletics, student life, and one's interactions with institutions. The goal of this work is neither to blame the University of Colorado for the rapes that occurred among its students, nor to relieve the perpetrators of their responsibility. It is the aim of this research to illustrate the systemic nature of rape culture and hence to show that rape is a wide spread societal problem that cannot be pathologized, individualized, or ignored

The role of institutional discourses in the perpetuation and propagation of rape culture on an American campus

Rape cultures in the United States facilitate acts of rape by influencing perpetrators’, community members’, and women who survive rapes’ beliefs about sexual assault and its consequences. While much of the previous research on rape in university settings has focused on individual attitudes and behaviors, as well as developing education and prevention campaigns, this research examined institutional influences on rape culture in the context of football teams. Using a feminist poststructuralist theoretical lens, an examination of newspaper articles, press releases, reports, and court documents from December 2001 to December 2007 was conducted to reveal prominent and counter discourses following a series of rapes and civil lawsuits at the University of Colorado. The research findings illustrated how community members’ adoption of institutional discourses discrediting the women who survived rape and denying the existence of and responsibility for rape culture could be facilitated by specific promotional strategies. Strategies of continually qualifying the women who survived rapes’ reports, administrators claiming ‘victimhood,’ and denying that actions by individual members of the athletic department could be linked to a rape culture made the University’s discourse more palatable to some community members who included residents of Boulder, Colorado and CU students, staff, faculty, and administrators. According to feminist poststructuralist theory, subjects continually construct their identities and belief systems by accepting and rejecting the discourses surrounding them. When community members incorporate rape-supportive discourses from the University into their subjectivities, rape culture has been propagated.Arts, Faculty ofGender, Race, Sexuality and Social Justice, Institute forGraduat

Comparative analysis of serotonin receptor (HTR1A/HTR1B families) and transporter (slc6a4a/b) gene expression in the zebrafish brain.

In this study we analyze 5-hydroxytryptamine [5-HT]; serotonin) signaling in zebrafish, an increasingly popular vertebrate disease model. We compare and contrast expression of the 5-HT transporter genes slc6a4a and slc6a4b, which identify 5-HT-producing neurons and three novel 5-HT receptors, htr1aa, htr1ab, and htr1bd. slc6a4a and slc6a4b are expressed in the raphe nuclei, retina, medulla oblongata, paraventricular organ, pretectal diencephalic complex, and caudal zone of the periventricular hypothalamus, in line with the expression profiles of homologues from other vertebrates. Our analysis of serotonin transporter (SERT)-encoding genes also identifies parallel genetic pathways used to build the 5-HT system in zebrafish. In cells in which 5-HT is synthesized by tph1, slc6a4b is used for re-uptake, whereas tph2-positive cells utilize slc6a4a. The receptors htr1aa, htr1ab, and htr1bd also show widespread expression in both the larval and adult brain. Receptor expression is seen in the superior raphe nucleus, retina, ventral telencephalon, optic tectum, thalamus, posterior tuberculum, cerebellum, hypothalamus, and reticular formation, thus implicating 5-HT signaling in several neural circuits. We also examine larval brains double-labeled with 5-HTergic and dopaminergic pathway-specific antibodies, to uncover the identity of some 5-HTergic target neurons. Furthermore, comparison of the expression of transporter and receptor genes also allows us to map sites of autoreceptor activity within the brain. We detect autoreceptor activity in the pretectal diencephalic cluster (htr1aa-, htr1ab-, htr1bd-, and slc6a4a-positive), superior raphe nucleus (htr1aa-, htr1ab-, and slc6a4a-positive), paraventricular organ (htr1aa-, htr1ab-, htr1bd-, and slc6a4b-positive), and the caudal zone of the periventricular hypothalamus (htr1ab- and slc6a4b-positive)

En komparativ livsløpsanalyse av elektriske og konvensjonelle kjøretøy

I 2015 gikk FNs 193 medlemsland sammen og vedtok 17 mål for en global, bærekraftig utvikling. Dette innebærer å ende fattigdom, bekjempe ulikheter og takle klimaendringene vi i dag står overfor. Klimagassutslipp fra menneskelig aktivitet har forårsaket en global temperaturøkning på 1℃ over førindustrielt nivå, og temperaturen fortsetter å øke. Bærekraftmål 13, Climate Action, har som hovedfokus å bekjempe klimaendringene og takle konsekvensene de fører med seg. Når det gjelder menneskeskapte klimagassutslipp, er transportsektoren en av de største bidragsyterne. I Norge står transportsektoren for omtrent 30% av de totale klimagassutslippene, hvorav 56% kommer fra veitrafikk. Elektriske biler og hybridbiler har blitt presentert som et viktig tiltak til et mer bærekraftig transportsystem sammenlignet med konvensjonelle kjøretøy drevet av fossilt drivstoff. Med dette arbeidet ønsker vi å besvare følgende problemstilling: Hvor store er klimagassutslippene fra produksjon og bruk av elbil, sammenlignet med hybrid-, diesel- og bensinbil? Vi har valgt å ta for oss åtte ulike energikjeder. Fem av energikjedene inkluderer elektrisk bil med forskjellig elektrisitetskilde, i tillegg til en ladbar hybridbil, en bensinbil og en dieselbil. Vi har utført en livsløpsanalyse av klimagassutslipp, basert på sekundærdata. Totale utslipp (Figur 1) består av produksjonsutslipp, fra kjøretøy og batteri, samt utslipp ved bruk. Bruksutslippet, Well-To-Wheel (WTW), består av to deler; Well-To-Tank (WTT) som tar for seg prosessene fra ressursutvinning til levering av drivstoff i kjøretøyet, og Tank-To-Wheel (TTW) som tar for seg drivstoffet fra det blir hentet på tanken, til det blir brukt for at bilen skal bevege seg