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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Ekonomické aspekty využití energie z fotovoltaické elektrárny / Economic aspects use of energy of photovoltaic plant

Cerman, Marek January 2013 (has links)
The major topic of this master‘s thesis is to create a complex model of general photovoltaic power plant (PVP). First chapters are engaged in research of photovoltaic. Growth of globally installed power and analysis of situation in Czech Republic are described in this section. The spectrum of conditions is introduced, from current legislative framework up to local Sun radiation. The actual technologies and their advantages are depicted, especially rate of utilization of energy. Expected trends of future development of conversion efficiency are mentioned, with prediction of production costs of photovoltaic. In context with those aspects, the question of grid parity achievement arises. The own assembled model of photovoltaic power plant has been created in Microsoft Excel. The mathematical apparatus is described in a separate chapter, individually solving technical part, which main result – the amount of yearly generated electricity, is applied for economical calculation. Final results are the usual economic indicators, mainly: Net Present Value (NPV), Internal Rate of Return (IRR), Levelized Cost of Electricity (LCOE). There is series of aspects defined by user in the model which may impact the amount of produced electricity and economics of user’s project, such as use of loan, replacement of converters, operational costs etc. These aspects are frequently neglected by project sellers. In the end, intended photovoltaic power plants of 2.75 kWp and 28.98 kWp are simulated by the model in real conditions of 2013. Sensitivity of impact of both proposals to the aspects mentioned above has been analyzed. In the conclusion the achieved results are summarized and the key factors which determine the PVP’s economic efficiency are assessed.
12

Super Collision Energy Transfer Studies in Single Collisions Between Vibrationally Hot Benzene Like Molecules and Ground State Bath Molecules: The Effect of Physical Properties of Donor and Bath Molecules on Super Collision Energy Transfer

Kim, Kilyoung 11 March 2011 (has links) (PDF)
This research is focused on single-collision energy transfer events between highly vibrationally excited benzene-like donor molecules and small bath molecules, CO2 and N2O in the vibrational ground level. Measuring how much energy is transferred from donors to bath molecules was accomplished by probing bath molecules scattered into specific-rotational states using a tunable Δv=0.0003 cm-1 solid state diode laser. The normalized energy transfer probability distribution function, P(E,E'), determined from energy gain information, is very useful in comparing collisional energy transfer efficiency between various collision systems. P(E,E') is also used to investigate the effects of donor and bath physical properties on collisional energy transfer. The first chapter details the C6H5F–CO2 system, which is the basis of a study on the effect of donor fluorination on strong collision energy transfer. The second chapter is about all fluorobenzene–CO2 systems, which investigates the effect of excess vibrational excitation energy of donors on supercollision energy transfer efficiency as well as donor fluorination effect. The third chapter focuses on how the physical properties of bath molecules affect supercollision energy transfer by measuring state-specific energy gain of N2O scattered into 0000, J=59−75. Instead of CO2, N2O was used as a bath molecule with a pyrazine donor to compare energy gain results of bath molecules with somewhat different physical properties. N2O and CO2 are isoelectronic and have similar mass, but N2O has a small dipole moment. Comparison of P(E,E') obtained from pyrazine–CO2, –N2O, –DCl, and –H2O systems helps to elucidate the effect of the bath physical properties on supercollision energy transfer efficiency. The last chapter is dedicated to the extension of the measurement range of N2O energy gain to the mid J states (J=37–75). In this chapter I discuss reliability of P(E,E') obtained from only high J tail as well as the correction of overall energy transfer rate constant.
13

[pt] A INFLUÊNCIA DOS DEFEITOS CRISTALINOS NA EFICIÊNCIA DE CÉLULAS SOLARES DE BANDA INTERMEDIÁRIA BASEADAS EM SEMICONDUTORES III-V / [en] THE ROLE OF DEFECTS ON THE EFFICIENCY OF INTERMEDIATE BAND SOLAR CELLS BASED ON III-V SEMICONDUCTORS

LIDA JANETH COLLAZOS PAZ 09 February 2021 (has links)
[pt] Neste trabalho tem sido investigado a presença de defeitos em células solares de banda intermediária (IB) de GaAs con pontos quânticos (PQs) de InAs. As três células estudadas contêm camadas de separação entre as camadas de PQs, as quais foram crescidas à diferentes temperaturas, e camadas delgadas de recobrimento dos PQs de diferentes espessuras. As eficiências de conversão de energia destas células foram medidas previamente, sendo que a célula com camadas de separação crescidas à 700 graus C e com camadas de recobrimento de 3 nm é a mais eficiente (6.9 por cento). As outras duas células com camadas de recobrimento de 6 nm apresentam menores eficiências: uma, com camadas separadoras crescidas à 700 graus C, com 5.1 por cento, e a outra, com camadas separadoras crescidas à 630 graus C, com 2.8 por cento. Estudos de DLTS e Laplace DLTS mostram que há um grande número de defeitos em altas concentrações na célula menos eficiente, enquanto nas outras duas células só é detetado o mesmo defeito EL2 em menores concentrações. Portanto, a redução dos defeitos induz o incremento da eficiência das células IB. Amostras adicionais foram crescidas e estudadas pelas mesmas técnicas, entre elas, três células solares com estruturas idênticas às das células IB, mas sem PQs, e quatro amostras GaAs mono-camada dopadas com carbono e silício, similares às camadas de contacto p e n das células IB. Do estudo das três células sem PQs foi possível determinar que alguns defeitos nas células IB são induzidos pelas condições de crescimento dos PQs ou são induzidos pela temperatura de crescimento das camadas separadoras. O estudo das amostras mono-camada indicou a presença de defeitos nos contatos p e n que podem armadilhar os portadores foto-excitados nas células sob operação e, portanto, limitar a eficiência delas. Os resultados deste trabalho contribuem para desenvolver novas estratégias para crescimento epitaxial de células IB no laboratório LabSem na PUC-Rio. / [en] Defects present in structures of intermediate band (IB) solar cells of GaAs with InAs quantum dots (QDs) grown by MOVPE have been investigated. The three studied IB solar cells differ in the growth temperature of the spacer layers that separate the InAs QD layers in the active region and the thickness of the thin layer that capping each QD layer. Previously, the energy conversion efficiencies of these cells were measured and the cell with the highest spacer layer-growth temperature (700 C degrees) and thinner capping layer (3 nm) showed the highest efficiency, about 6.9 percent. The cells with thicker capping layers (6 nm) showed lower efficiencies, one of them, with spacer layers grown at 700 C degrees, reaching 5.1 percent, and the other one, with spacer layers grown at 600 C degrees, reaching only 2.8 percent. In this work, DLTS and Laplace DLTS studies show that the cell with the lowest efficiency has the largest number and highest concentrations of defects, unlike the other two cells, which have only one trap, EL2, in lower concentrations. These results demonstrate that the different growth conditions are determinant for the formation of defects and that the defect reduction leads to the increase of the IB solar cell efficiencies. Other samples were also grown and studied by the same techniques: three solar cells with identical structure as the IB solar cells, but without QDs, and individually doped GaAs samples that represent the p and n contact sides of the IB solar cells. From the study of the cells without QDs, the origin of some defects in the IB solar cells was found to be related to the QD growth conditions or related to the spacer layer-growth temperature. The study of the GaAs samples indicated the presence of defects in the p and n sides that could trap photo-excited carriers collected through these contacts during cell operation and thus reduce the efficiency. The results of this work allow developing new strategies to improve the epitaxial growth quality of IB solar cells in the laboratory of semiconductors LabSem of PUC-Rio where the studied samples were grown.
14

Investigation of the photo-induced charge transfer in organic semiconductors via single molecule spectroscopy techniques

Lee, Kwang Jik 06 November 2012 (has links)
Photo-induced charge transfer which occurs between molecules or different parts of a large molecule is the pivotal process related to performances of organic electronics. In particular, injection of charge carriers into conjugated polymers and dissociation of photo-generated excitons at the heterojunction between a donor and acceptor system are of great importance in determining the luminescence efficiency of organic light emitting diodes (OLEDs) and solar energy conversion efficiency of organic solar cells, respectively. However, the complex nature of organic semiconductors as well as complicated primary processes involved in the functioning of these devices have prevented us from understanding unique characteristics of these processes and thereby engineering better materials for higher performances. In this dissertation, two different types of photo-induced (or -related) charge transfer processes occurring in organic semiconductors were investigated by using single molecule spectroscopy (SMS) techniques to unravel the complexities of these processes. The carefully designed functioning capacitor-like model devices similar to OLEDs and photovoltaic cells were fabricated where isolated single nanoparticles were introduced as an active medium to mitigate the complexities of these materials. We observed that injection of positively charged carriers (holes) into poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) single nanoparticles from the carbazole hole transport layer does not occur in the absence of light. We denoted the observed hole injection in aid of light as the light-induced hole transfer mechanism (LIHT). It was revealed that the charging dynamics are highly consistent with a cooperative charging effect. In addition, the LIHT was proposed as the possible source for the formation of deep trapped hole in organic devices. Local exciton dissociation yields across a nanostructured domain between poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT) single nanoparticles and either poly(9,9- dioctylfluorene - co - bis-N,N- (4 -butylphenyl)-bis-N,N-phenyl-1,4-phenylene diamine) (PFB) or poly(9,9-dioctylfluorene-co-N-(4-butylphenyl)diphenylamine) (TFB) film in model photovoltaic devices was also investigated. A wide distribution of exciton dissociation yields was observed from each nanodomain due to the device geometry. The observed hysteresis in fluorescence voltage curve was ascribed to accumulated charges following charge separations. The dynamics of charge separation under the applied electric field was described in more detail. / text
15

Bewertung verschiedener Bolzenschussbetäubungsapparate beim Rind hinsichtlich ihrer Effektivität und ihres Einflusses auf den Ausblutungsgrad

Dörfler, Katharina 24 February 2015 (has links)
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16

溫室氣體排放管制趨勢下-台灣石化產業之發展策略 / The development strategies of petrochemical industry in Taiwan-under the trend of severe GHG emission control

蔡錫津 Unknown Date (has links)
近年來,隨著能源價格不斷飆漲以及溫室氣體大量排放造成的氣候異常變化,引起世界各國對於提高能源使用效率與加強溫室氣體排放管制的重視。溫室氣體大多由化石燃料燃燒所產生。因此,一般被視為能耗較高的發電、鋼鐵、水泥以及石化等產業,遂成為眾所矚目而被要求加強溫室氣體排放管制的主要產業。未來的產業發展規劃,必需兼顧經濟與環保,否則必將被世界潮流所淹沒。 因應全球溫室氣體排放管制趨勢,就台灣經濟發展面、財政建設面、環境永續經營面等層面考量分析,現階段石化產業之發展應對產業競爭力及環境保護做更多且更審慎的考量。於產業競爭力部分,建議中油開放民營,並運用部份釋股取得的資金,一方面引進先進的製程技術及進行設備更新,提升企業競爭力;另一方面整合國內仰賴台灣中油公司供料且在各產品領域擁有數十年營運經驗的中下游業者,建構泛中油體系的石化經營團隊。如此泛中油體系與國內另一石化產品鏈已相當完整的台塑體系,形成兩大石化體系,互為良性競爭。於環境保護方面,則建議我國應終止國光石化投資案,降低溫室氣體排放量,並藉提升廠商製程效率減少能耗,如此將使經濟發展及環境保護得以兼顧,亦達成原興建國光計畫之目的。 而未來台灣石化產業發展策略,技術發展需長期向下扎根,產品則朝高值化、精緻化發展,開發低能耗、低污染之替代能源,提升產品的附加價值,並將大宗石化耗能的產品移往海外能源低廉的地區,持續提升產業競爭力,並達成溫室氣體減少排放為目標。如是,台灣在環境保護日益重視之趨勢下,石化產業也得以永續發展。 / The high energy cost and the unusual climate change due to increasing green house gases(GHG)emission in recent years have attracted the global attentions and called for improvement of energy utilization efficiency and enhancement of GHG emission control. GHG are mostly produced by the combustion of fossil fuels. And the higher energy consumption industries such as power generation, steel, cement and petrochemical industries are thus strongly requested to reduce GHG emission. Economic development and environmental protection both are needed to be equally evaluated in the planning of future industry development. Taking petrochemical industry as an example, many of its mid-stream and down-stream products have become an unseparable part and of our daily life. In Taiwan, it has been over half century since the establishment of petrochemical industry, and now become top 10 petrochemical production countries in the world. The production value of petrochemical-related industries are very close to 4 trillion NT dollars, about 30% of total production value of domestic manufacturing sectors. Petrochemical industry and electronic industry are the two strong arms in supporting national economic growth. As a very important industry in Taiwan, however, the intensity of its GHG emission is only next to steel industry. The significant technology improvement in petrochemical industry has been achieved since the installation of the existing refinery, naphtha crackers and many petrochemical mid-stream production plants in Taiwan. It is well recognized that the GHG emission will be greatly reduced if the advanced technologies are introduced and the old facilities are revamped. Therefore, the writer would like to address a different approach toward KuoKuang Petrochemical Project which the government is giving an impetus to its execution. Here the writer would propose Taiwan CPC company, the state-owned petroleum company and the leader of Kuokuang Petrochemical Project, to become privatized after asset re-evaluation and collect some government capital from privatization through issuance of part of its shares to the open market. The capital thus collected can be used for enterprise reform. The important items of the enterprise reform include but not limited to introduction of the advanced technologies, revamping of existing facilities and establishment of a new well-integrated petrochemical conglomerate through mutual investment between Taiwan CPC and the mid-stream companies that rely raw material supplies from Taiwan CPC. From viewpoints of both economy and environment, government policy of implementation of KuoKuang Petrochemical Project is worthy for reconsideration. Formation of a CPC-lead petrochemical conglomerate would also benefit the current petrochemical companies that rely on raw material supplies from Taiwan CPC as their operation efficiencies would improved from business intergration. The newly formed conglomerate would be more powerful in further business development and more competitive in world market. They would have more resources to explore their potential in advanced technology development, in new business fields such as biomass energy, solar energy and so on. The CPC-lead petrochemical conglomerate would be able to enchance its competitiveness to another domestic petrochemical giant, Taiwan Formosa Group, and other petrochemical giants in the global market.
17

Síntese e caracterização de filmes de óxidos metálicos nanoparticulados para aplicação em células solares sensibilizadas por corante (DSCs)

Paula, Leonardo Ferreira de 29 April 2014 (has links)
In this work, thin and compact films of TiO2, Nb2O5 and WO3 nanoparticles were prepared to be used as contact/blocking layer in dye sensitized solar cells (DSCs). The films were produced by deposition of 30 bilayers of TiO2(ac)/TiO2(bas), TiO2(ac)/Nb2O5(bas) and TiO2(ac)/WO3(bas) using the layer-by-layer technique (LbL) from nanoparticle sols of TiO2 (pH = 2 and 10), Nb2O5 (pH = 10) and WO3 (pH 10) prepared by sol-gel method. The TiO2/TiO2 and TiO2/Nb2O5 underlayers resulted in an increase of 25% and 87% respectively, in the efficiency of DSCs when compared to those without the contact/blocking layers. The application of TiO2/WO3 films did not result in any improvement of DSC efficiency. Factors such as thickness, nanoparticles homogeneity, oxides concentration on the films and roughness directly influence on the efficiency of such films as contact/blocking layer. Field Emission Scanning Electron Microscopy (FESEM) and Atomic Force Microscopy (AFM) images, confirmed that all films are constituted by spherical nanoparticles with homogeneous diameters smaller than 20 nm, resulting on compact and low porous surfaces. This morphology ensures a physical barrier between the electrolyte and the conductive glass used as electrode in DSCs. The TiO2/TiO2 and TiO2/Nb2O5 films also exhibited higher roughness than the surface of the conductive glass without the bilayers, which increases the interaction with the mesoporous TiO2 film. The molar ratios of the species present on the films are controlled by the pH employed during deposition, and were determined by X- ray photoelectron spectroscopy (XPS). The Ti4+/Nb5+ and Ti4+/W6+ ratios were 1.6 and 19 respectively, which evidences a higher concentration of TiO2 nanoparticles on the films. For a better understanding of the role of the bilayers on the charge transfer processes, the substrates were analyzed by Electrochemical Impedance Spectroscopy (EIS). The electronic properties of the oxides also influence the efficiency of the LbL films as contact/blocking layers. Due to its higher band gap, Nb2O5 nanoparticles impose an electronic barrier to the electrons transfer from the conductive substrate to the electrolyte, additionally to the physical barrier. / Neste trabalho foram preparados filmes finos e compactos de óxidos nanoparticulados de TiO2, Nb2O5 e WO3 para a aplicação como camada de contato/bloqueio em células solares sensibilizadas por corante (DSCs). Os filmes foram produzidos pela deposição de 30 bicamadas de TiO2(ác)/TiO2(bás), TiO2(ác/Nb2O5(bás) e TiO2(ác)/WO3(bás) utilizando a técnica de automontagem (Layer-by-Layer ou LbL), a partir dos sóis nanoparticulados de TiO2 (pH = 2 e 10), Nb2O5 (pH = 10) e WO3 (pH = 10) sintetizados pelo método sol-gel. A presença das bicamadas de TiO2/TiO2, TiO2/Nb2O5 gerou aumentos relativos na eficiência das DSCs de 25% e 87% respectivamente, quando comparadas às DSCs sem as bicamadas. Já o filme de TiO2/WO3 não gerou nenhuma melhoria na eficiência das DSCs. Fatores como a espessura, homogeneidade das nanopartículas, concentração dos óxidos nos filmes e a rugosidade influenciam diretamente na eficiência dos filmes como camada de contato/bloqueio. Imagens de Microscopia Eletrônica de Varredura com Emissão de Campo (MEV-FEG) e Microscopia de Força Atômica (MFA) confirmaram que todos os filmes apresentaram nanopartículas esféricas com diâmetros homogêneos e menores que 20 nm, o que acarreta na formação de superfícies compactas e pouco porosas. Esta morfologia garante uma barreira física entre o eletrólito e a superfície do vidro condutor utilizado como eletrodo nas DSCs. Os filmes de TiO2/TiO2 e TiO2/Nb2O5 apresentaram também rugosidades maiores que a da superfície do vidro condutor sem as bicamadas, o que aumenta a interação entre com o filme de TiO2 mesoporoso. As razões molares das espécies presentes nos filmes são controladas pelo pH empregado durante as deposições, e foram determinadas por Espectroscopia de Fotoelétrons Excitados por raios-X (XPS). As razões Ti4+/Nb5+ e Ti4+/W6+ foram de 1,6 e 19 respectivamente, o que evidencia uma maior quantidade de nanopartículas de TiO2 nos filmes. Para melhor entender o papel das bicamadas nos processos de transferência de cargas, os substratos foram analisados por Espectroscopia de Impedância Eletroquímica (EIE). As propriedades eletrônicas dos óxidos também influenciam na eficiência dos filmes automontados como camada de contato/bloqueio. Devido ao seu maior valor de band gap, as nanopartículas de Nb2O5 impõem, além de uma barreira física, uma barreira eletrônica para a transferência dos elétrons do substrato condutor para o eletrólito. / Mestre em Química
18

Critical Transmission Sectors of Energy-Water-GHG Nexus / Critical Transmission Sectors of Energy-Water-GHG Nexus

Wang, Xuechao January 2020 (has links)
Využití vody, spotřeba energie a emise skleníkových plynů (GHG) jsou rozhodujícími ukazateli a do značné míry souvisí s udržováním nebo dosahováním environmentální a sociální udržitelnosti. Tato práce prezentuje vyvinuté metodiky. Představuje také provedené případové studie, které prozkoumaly a identifikovaly Water-Energy-GHG Nexus (WEGN) z pohledu dodavatelského řetězce. Pro analýzu a návrh sítě WEGN jsou navrženy tři metodiky, které jsou založeny na nové aplikaci a integraci modelu vstup-výstup (IO), geografického informačního systému (GIS) a sítě dodavatelského řetězce (SCN), a zároveň řeší výzvy, které dříve neumožňovali praktické implementace. Použitelnost těchto metod je prokázána třemi komplexními případovými studiemi zaměřenými na odvětvovou environmentální účinnost, regionální environmentální účinnost a kritické přenosy WEGN. Mezi mé příspěvky v této oblasti patří: i. Nový nástroj pro hodnocení založený na IO pro identifikaci regionální environmentální účinnosti z hlediska WEGN, zejména pro regiony, které jsou úzce propojenyobchodem. ii. Pokročilá integrace metodik GIS a IO (GIS-IO) za účelem odhalení a mapování sítě WEGN, sledování kritických meziregionálních a sektorových toků WEGN, vyjasnění regionálních, odvětvových a celosvětových vzorců sítě WEGN a určení souvisejících výhod pro různé regiony. iii. Efektivní metoda hodnocení založená na IO a SCN pro kvantifikaci sektorových koeficientů WEGN. Navrhované metodiky, s podporou sady komplexních základních rovnic, transformují komplikované výzvy identifikace a analýzy sítě WEGN do snadno srozumitelného formátu, z čehož vznikají robustní řešení pro zlepšení posuzování environmentální udržitelnosti a zmírnění environmentálních tlaků. Například v jedné z případových studií ukazují výsledky nového přístupu GIS-IO zjevné rozdíly mezi různými zeměmi v rámci EU27, mezi různými sektory a také pokud srovnáme EU27 jako blok zemí, s ostatními státy světa. Analýza ukázala, že země EU27 přispěly o 1.4 Gt nižšími emisemi CO2, o 64.5 Gm3 menší spotřebou vody a 4.9 × 104 PJ nižší spotřebou energie ve srovnání se zbytkem světa, přičemž generovaly ekvivalentní ekonomickou produkci. To má dramatický dopad na globální prostředí. Největší úspěch v CWE mezi zeměmi EU27 měly Německo, Francie a Itálie. Práce doporučuje, aby EU27 poskytovala více technické podpory zemím, které těchto výsledků nedosahují, aby se zvýšila účinnost využívání zdrojů.
19

Efektivní provoz moderních jednotek EVO / Effective operation of up-to-date waste-to-energy units

Cafourková, Tereza January 2009 (has links)
The main content of this thesis is a suggestion of computing system for efficient energy manufacture. The introduction devotes to description of up-to-date waste-to-energy units (EVO), it concentrates on Incinerator of municipal wastes of TERMIZO a.s., specifically. In the main body of this work is the data analysis of factory journal that has been implemented, results have been used as mathematical model output value. These activities are necessary for computing system suggestion. Resulting optimization of batch wasting plan with maximum economic effect for entrepreneur is the main output of this work. Conclusion consists of environmental and economic evaluation of operation of up-to-date waste-to-energy units and offers another optimization posibility.

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