1,873 research outputs found

    Sensitivity of the Drift-Diffusion Approach in Estimating the Power Conversion Efficiency of Bulk Heterojunction Polymer Solar Cells

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    There are numerous theoretical approaches to estimating the power conversion efficiency (PCE) of organic solar cells (OSCs), ranging from the empirical approach to calculations based on general considerations of thermodynamics. Depending on the level of abstraction and model assumptions, the accuracy of PCE estimation and complexity of the calculation can change dramatically. In particular, PCE estimation with a drift-diffusion approach (widely investigated in the literature), strongly depends on the assumptions made for the physical models and optoelectrical properties of semiconducting materials. This has led to a huge deviation as well as complications in the analysis of simulated results aiming to understand the factors limiting the performance of OSCs. In this work, we intend to highlight the complex relation between mobility, exciton dynamics, nanoscale dimension, and loss mechanisms in one framework. Our systematic analysis represents key information on the sensitivity of the drift-diffusion approach, to estimate how physical parameters and physical processes bind the PCE of the device under the influence of structure, contact, and material layer properties. The obtained results ultimately led to recommendations for putting effort into certain properties to get the most out of avoidable losses, presented the impact and importance of modification of material properties, and in particular, recommended to what degree the design of new material could improve OSC performance

    A letter to A.H. Esq., concerning the stage [electronic resource]

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    A defense of the stage, in answer to Jeremy Collier's Short view of the immorality and profaneness of the English stage."The initials in the title [i.e. A.H.] have been identified as those of Anthony Hammond. Charles Hopkins has been suggested as the probable author." Cf. NUC pre-1956.Reproduction of original in Huntington Library.WingElectronic reproduction

    De kosten van een zandsuppletie op het strand van de Kop van Goeree uitgevoerd met behulp van de zogenaamde "Punaise"

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    In het 1e deel van het afstudeerverslag van A.H. van Berk (lit. 1) werd de vraag gesteld of een baggersysteem voor het kustonderhoud van de Kop van Goeree met de punaise (fig. 0) in één van de wingebieden A, B of C (fig. 2) kan konkurreren met een systeem met een cutterzuiger in wingebied E. Voor het antwoord op deze vraag zijn de kosten van zowel de uitvoering met de punaise als die met de cutterzuiger bepaald. Deze kosten zijn omgerekend naar de gemiddelde jaarlijkse kosten voor het kustonderhoud en onderling vergeleken. In het tweede deel wordt een handleiding gegeven voor de berekening van de jaarlijkse kosten van het kustonderhoud van de lop van Goeree door zandsuppietie a.b.v. de Punaise.Hydraulic EngineeringCivil Engineering and Geoscience

    Silicon Nanowire Field Effect Transistor Modeling

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    While theories based on classical physics have been very successful in helping experimentalists design microelectronic devices, new approaches based on quantum mechanics are required to accurately model nanoscale transistors and to predict their characteristics even before they are fabricated. Advanced Nanoelectronics provides research information on advanced nanoelectronics concepts, with a focus on modeling and simulation. Featuring contributions by researchers actively engaged in nanoelectronics research, it develops and applies analytical formulations to investigate nanoscale devices. The book begins by introducing the basic ideas related to quantum theory that are needed to better understand nanoscale structures found in nanoelectronics, including graphenes, carbon nanotubes, and quantum wells, dots, and wires. It goes on to highlight some of the key concepts required to understand nanotransistors. These concepts are then applied to the carbon nanotube field effect transistor (CNTFET). Several chapters cover graphene, an unzipped form of CNT that is the recently discovered allotrope of carbon that has gained a tremendous amount of scientific and technological interest. The book discusses the development of the graphene nanoribbon field effect transistor (GNRFET) and its use as a possible replacement to overcome the CNT chirality challenge. It also examines silicon nanowire (SiNW) as a new candidate for achieving the downscaling of devices. The text describes the modeling and fabrication of SiNW, including a new top-down fabrication technique. Strained technology, which changes the properties of device materials rather than changing the device geometry, is also discussed. The book ends with a look at the technical and economic challenges that face the commercialization of nanoelectronics and what universities, industries, and government can do to lower the barriers. A useful resource for professionals, researchers, and scientists, this work brings together state-of-the-art technical and scientific information on important topics in advanced nanoelectronics

    Determinanten van kennisintensieve onderzoeks- en ontwikkelingssamenwerking

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    It is becoming increasingly important for companies to ensure a continuing supply of new knowledge. The development of innovative production processes and marketing strategies as well as better products and services improves the competitive position of firms on the world market. This is of special interest to Dutch firms who have only a small and open home market. The principal research question addressed in this thesis concerns the determinants that influence companies in their choice of whether or not to enter into a knowledge-intensive research and development collaboration. This thesis also looks in detail at the role of publicly financed research institutions such as universities, in the setting of the company innovation process as well as at cooperation among private firms. About 13% of all innovative firms in the Netherlands are engaged in some sort of knowledge-intensive research and development collaboration. Knowledge spillovers are an important reason to reject collaboration as a means of acquiring knowledge because spillovers worsen the appropriability conditions, thus decreasing the economic benefits gained from innovative efforts. In correspondence with the literature we find that a high level of R&D-intensity of the partners involved is a very important prerequisite for entering into knowledge intensive R&D-collaboration. Furthermore an important finding is that the probability of entering into a knowledge-intensive R&D-collaboration increases proportionally to the size of the firm. Most innovative firms choose to be engaged in both private and public types of knowledge intensive R&D-collaboration. From this it can be concluded that public and private types of collaboration are complementary to one another. Knowledge intensive R&D-collaboration is also of strategic importance making the decision whether to introduce either improved or newly-developed products onto the market. Firms engaged in knowledge intensive R&D-collaboration more often choose to introduce new products instead of improved products onto the market.Technology, Policy and Managemen

    Metingen met een proportionele teller bij beta-desintegratie

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    Electrical Engineering, Mathematics and Computer Scienc
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