15 research outputs found

    Small business innovation research. Abstracts of completed 1987 phase 1 projects

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    Non-proprietary summaries of Phase 1 Small Business Innovation Research (SBIR) projects supported by NASA in the 1987 program year are given. Work in the areas of aeronautical propulsion, aerodynamics, acoustics, aircraft systems, materials and structures, teleoperators and robotics, computer sciences, information systems, spacecraft systems, spacecraft power supplies, spacecraft propulsion, bioastronautics, satellite communication, and space processing are covered

    Handbook of solar-terrestrial data systems, version 1

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    The interaction between the solar wind and the earth's magnetic field creates a large magnetic cavity which is termed the magnetosphere. Energy derived from the solar wind is ultimately dissipated by particle acceleration-precipitation and Joule heating in the magnetosphere-ionosphere. The rate of energy dissipation is highly variable, with peak levels during geomagnetic storms and substorms. The degree to which solar wind and magnetospheric conditions control the energy dissipation processes remains one of the major outstanding questions in magnetospheric physics. A conference on Solar Wind-Magnetospheric Coupling was convened to discuss these issues and this handbook is the result

    Under the influence: Understanding the thermodynamic and optical properties of stimuli-responsive complex organic systems

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    A solid understanding of the optical and thermodynamic features of a chemical system is indispensable for the development and optimisation of new materials. Stimuli-responsive substances may be incorporated into optoelectronic devices, such as organic light-emitting diodes or sensory systems. Especially in recent years, photo-sensitive molecular aggregates and redox-switchable supramolecular architectures have proven their merit. Due to their flexible components, these noncovalently bound systems often exhibit perplexing behaviour when submitted to external stimuli, such as light or electric potential. Examples addressed in this thesis include substitution-pattern controlled fluorescence quantum yields and redox-induced switchable spectroscopic responses. While there are plenty of powerful experimental techniques around to examine the underlying mechanisms, high-level quantum-chemical approaches are often crucial for a final and conclusive interpretation of one’s experimental results. The aim of this thesis is to examine the broad scope of stimuli-responsive molecular aggregates and demonstrate the versatility of quantum-chemical methods to study their optical and thermodynamic properties. To this end, I will present six different publications separated into two parts, A and B, each contributing three papers. Due to the variety of the molecules studied in this work, computational protocols effectively tailored for each project had to be developed. The applied methods are used to study electronic as well as molecular structures and include solvent and finite-temperature effects for comparison to experiment. A major emphasis is put on the evaluation of excited states. In addition to the valuable knowledge we could gain about the underlying chemistry of the investigated systems, these protocols serve as a potent tool for the examination of similar problems. All papers include combined approaches of theory and experiment and, hence, showcase the efficient collaboration of experimental and theoretical groups. In part A, I will present a new class of fluorescent dyes: Diaminodicyanoquinones (DADQs). Owing to a large dipole moment, redox-activity, and tailorable fluorescence, DADQs are promising candidates for a variety of applications in the context of molecular electronics. Papers A1-A3 effectively follow a bottom-up approach examining monomers, aggregates in solution, and the solid state with a focus on their absorption and emission features. In all three publications, remarkable experimental observations are made including notably high quantum yields and counterintuitive concentration-dependent absorption peaks. In each case, a combination of multiple high-level state-of-the-art quantum-chemical approaches including DFT/MRCI (density functional theory/multi-reference configuration interaction) is utilised to thoroughly investigate the chemical systems and find explanations for the often unexpected experimental results. Part B presents three different redox-responsive supramolecular systems, each displaying intriguing thermodynamic or optical properties, which could only be fully unravelled by rigorous theoretical studies. Redox-responsiveness is induced either by incorporation of the organosulfur compound tetrathiafulvalene (TTF) or by complexation with a redox-active molecule such as cobaltocene. A variety of different quantum-chemical methods based on DFT and time-dependent DFT (TD-DFT) is employed in the course of part B to study switching mechanisms and rationalise thermodynamic features. In this way, the examined supramolecular structures are now equipped with an in-depth understanding of their often non-trivial chemical behaviour which paves the way towards applications in novel optoelectronic technologies.Ein klares Verständnis der optischen und thermodynamischen Eigenschaften chemischer Systeme ist unabdingbar für die Entwicklung und Optimierung neuer Materialien. Substanzen, die sich von äußeren Einflüssen steuern lassen, können in optoelektronische Geräte wie organische Leuchtdioden oder Sensorsysteme eingebaut werden. Besonders in den vergangenen Jahren haben photo-sensitive molekulare Aggregate und redox-schaltbare supramolekulare Architekturen ihren Wert unter Beweis gestellt. Aufgrund ihrer flexiblen Einzelkomponenten zeigen diese nichtkovalent gebundenen Systeme oftmals ein verblüffendes Verhalten, wenn sie durch äußere Reize wie Licht oder ein elektrisches Potenzial beeinflusst werden. Beispiele, die in dieser Dissertation adressiert werden, sind Substitutionsmuster-kontrollierte Fluoreszenzquantenausbeuten und redox-induzierte schaltbare spektroskopische Signale. Während es eine große Anzahl an vielseitigen experimentellen Methoden gibt, um die zugrundeliegenden Mechanismen zu studieren, ist oftmals die Verwendung anspruchsvoller quantenchemischer Ansätze vonnöten, um eine endgültige und schlüssige Interpretation der experimentellen Ergebnisse zu erhalten. Diese Arbeit ist darauf ausgerichtet, die Vielseitigkeit von durch äußere Reize steuerbare (eng. stimuli-responsive) molekulare Aggregate zu analysieren und die Flexibilität von quantenchemischen Methoden aufzuzeigen, die zur Untersuchung ihrer optischen und thermodynamischen Eigenschaften genutzt werden. Zu diesem Zweck werde ich sechs Publikationen vorstellen, aufgeteilt in zwei Teile, A und B, die jeweils drei Arbeiten beitragen. Aufgrund der Vielfältigkeit der untersuchten Moleküle wurden Berechnungsverfahren entwickelt, die im wesentlichen für jedes Projekt aufs Neue maßgeschneidert werden mussten. Die angewandten Methoden sind darauf ausgelegt, sowohl elektronische als auch molekulare Strukturen zu beschreiben und Solvatations- und Temperatureinflüsse für den Vergleich zu Experimenten mit einzubeziehen. Ein großes Augenmerk liegt auf der Analyse von angeregten Zuständen. Abgesehen von den wertvollen Erkenntnissen, die wir über die zugrundeliegende Chemie der untersuchten Systeme erhalten konnten, dienen die entwickelten Berechnungsansätze als leistungsfähiges Werkzeug für das Herangehen an ähnliche Probleme. Alle Publikationen beinhalten aus Theorie und Experiment kombinierte Ansätze und illustrieren damit die effiziente Zusammenarbeit von theoretisch und experimentell arbeitenden Forschungsgruppen. In Teil A werde ich eine neuartige Klasse von fluoreszierenden Farbstoffen vorstellen: Diaminodicyanochinone (DADQs). Aufgrund ihrer hohen Dipolmomente, Redoxaktivität und einstellbaren Fluoreszenz sind DADQs vielversprechende Kandidaten für eine Vielzahl von Anwendungen im Kontext der molekularen Elektronik. Publikationen A1-A3 folgen im wesentlichen einem Bottom-up-Ansatz, bei dem es um die Untersuchung von Monomeren, Aggregaten in Lösung und Festkörperstoffen geht, wobei ein Fokus auf deren Absorptions- und Emissionseigenschaften liegt. In allen drei Arbeiten sind erstaunliche experimentelle Beobachtungen gemacht worden wie beispielsweise extrem hohe Fluoreszenzquantenausbeuten oder kontraintuitive konzentrationsabhängige Absorptionsbanden. In jeder Untersuchung wurde eine Vielzahl an hochmodernen quantenchemischen Methoden inklusive des DFT/MRCI (Dichtefunktionaltheorie/Multireferenz-Konfigurationswechselwirkung) Ansatzes genutzt, um eine ausführliche Analyse der chemischen Systeme zu gewährleisten und Erklärungen für die unerwarteten experimentellen Beobachtungen zu finden. In Teil B werden drei verschiedene redox-stimulierbare supramolekulare Systeme präsentiert, die alle interessante thermodynamische und optische Eigenschaften aufzeigen, welche nur durch den sorgfältigen Einsatz von theoretischen Methoden vollkommen verstanden werden konnten. Redox-Stimulierbarkeit wurde entweder durch die Eingliederung der schwefelorganischen Verbindung Tetrathiafulvalen (TTF) oder durch Komplexierung mit einem redox-aktiven Molekül wie Cobaltocen induziert. Verschiedene quantenchemische auf DFT und zeitabhängiger DFT (TD-DFT) basierende Ansätze wurden in Teil B benutzt, um Schaltmechanismen zu untersuchen und thermodynamische Eigenschaften zu rationalisieren. Dadurch erhielten wir ein tiefes Verständnis der oftmals alles andere als trivialen chemischen Verhaltensweisen der supramolekularen Strukturen, was den Weg zur Anwendung in neuartigen, optoelektronischen Technologien ebnet

    Factors Influencing Customer Satisfaction towards E-shopping in Malaysia

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    Online shopping or e-shopping has changed the world of business and quite a few people have decided to work with these features. What their primary concerns precisely and the responses from the globalisation are the competency of incorporation while doing their businesses. E-shopping has also increased substantially in Malaysia in recent years. The rapid increase in the e-commerce industry in Malaysia has created the demand to emphasize on how to increase customer satisfaction while operating in the e-retailing environment. It is very important that customers are satisfied with the website, or else, they would not return. Therefore, a crucial fact to look into is that companies must ensure that their customers are satisfied with their purchases that are really essential from the ecommerce’s point of view. With is in mind, this study aimed at investigating customer satisfaction towards e-shopping in Malaysia. A total of 400 questionnaires were distributed among students randomly selected from various public and private universities located within Klang valley area. Total 369 questionnaires were returned, out of which 341 questionnaires were found usable for further analysis. Finally, SEM was employed to test the hypotheses. This study found that customer satisfaction towards e-shopping in Malaysia is to a great extent influenced by ease of use, trust, design of the website, online security and e-service quality. Finally, recommendations and future study direction is provided. Keywords: E-shopping, Customer satisfaction, Trust, Online security, E-service quality, Malaysia

    NASA-HBCU Space Science and Engineering Research Forum Proceedings

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    The proceedings of the Historically Black Colleges and Universities (HBCU) forum are presented. A wide range of research topics from plant science to space science and related academic areas was covered. The sessions were divided into the following subject areas: Life science; Mathematical modeling, image processing, pattern recognition, and algorithms; Microgravity processing, space utilization and application; Physical science and chemistry; Research and training programs; Space science (astronomy, planetary science, asteroids, moon); Space technology (engineering, structures and systems for application in space); Space technology (physics of materials and systems for space applications); and Technology (materials, techniques, measurements)
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