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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.
321

Chemo-enzymatic modification of high-kappa kraft pulps with laccase

Chandra, Richard P. 07 1900 (has links)
No description available.
322

Characterization of chemical pulp fiber surfaces with an emphasis on the hemicelluloses

Sjöberg, John January 2003 (has links)
No description available.
323

Ultrastructural Aspects of Pulp Fibers as Studied by Dynamic FT-IR Spectroscopy

Åkerholm, Margaretha January 2003 (has links)
<p>Dynamic (or 2D) FT-IR spectroscopy in combination withpolarized IR irradiation has been used in this work to studywood polymer orientation and interactions on theultrastructural level in wood fibers in the native state aswell as the effects of different pulping processes. The woodpolymer interactions were studied under both dry and humidconditions.</p><p>The matrix of lignin and hemicelluloses located between thewell-ordered cellulose fibrils in the wood cell wall of sprucewas here shown to be more highly ordered than has earlier beenrevealed. It was confirmed that glucomannan is orientedparallel to the cellulose fibrils and is highly coupled to it.The lignin was also shown to have a main orientation in thestructure although this is probably not as strong as that ofglucomannan. The orientation of the lignin may derive from thefact that the polysaccharides act as templates during thelignification of the cell wall. This organization implies thatnot only the cellulose but also the lignin and thehemicelluloses have different mechanical properties in thelongitudinal and cross-fiber directions.</p><p>The ability to gain molecular information on the stresstransfer in polymers with dynamic FT-IR spectroscopy made itpossible to verify experimentally earlier molecularcalculations on the stress transfer within the cellulose chain.It was also possible to show, on the molecular level, thedominant importance of the cellulose fibrils for the stresstransfer in the longitudinal direction of pulp fibers,including lignin-rich mechanical pulp fibers. The glucomannanof softwood fibers was also shown to participate in the stresstransfer in the fiber direction indicating a close associationwith the cellulose, whereas the xylan showed no dynamicresponse. Already under dry conditions, the lignin was shown tohave a more viscoelastic response than the polysaccharidesduring the loading of pulp fibers and it was thus able to moveindependently of the cellulose.</p><p>The enhanced spectral resolution obtained with dynamic FT-IRspectroscopy made it possible to study the crystalstructure/chain order of cellulose in pulp fibers. Thepossibility of following changes in the relative cellulose Iallomorph composition of pulp fibers was demonstrated for somechemical pulps.</p><p>Dynamic FT-IR experiments under humid conditions and ofelevated temperatures made it possible to study the softeningof the biopolymers in their native environment. This was alsodemonstrated for some different pulps, and this may be apromising tool for obtaining viscoelastic information on themolecular level in composite systems such as wood fibers.</p><p><b>Keywords:</b>cellulose, cooperation, crystallinity, dynamictest, glucomannan, hardwood, holocellulose, humidity, infraredspectroscopy, kraft pulp, lignin, mechanical pulp, orientation,polarised light, softwood, strain, sulphite pulp,viscoelasticity, xylan</p>
324

Bautechnik-Forum Chemnitz 2003

Baradiy, Saad, Möckel, Wolfgang, Nitzsche, Gunhild, Urbaneck, Thorsten 10 June 2004 (has links) (PDF)
Inhalt: Energieforschungsprogramm des Bundes: Förderkonzept solar optimiertes Bauen Planungsfehler beim Feuchte- und Wärmeschutz von Fußbodenkonstruktionen Heat insulation and indoor climate control in arid areas (Toshky Region) Hygrisch motivierter Wärmeschutz Anlagentechnische Möglichkeiten für die EnEV – Was tun ? Mangelhafter Schallschutz von Gebäuden – Beispiele aus der Praxis Biomassenutzung zur Kraft- und Wärmebereitstellung - ein Blick nach Österreich Challenges and opportunities for solar energy use and energy efficiency measures for buildings and settlements in Dalmatia Wärmecontracting - Eine Dienstleistung zur Kostenminimierung ?
325

Zur Bereitstellung positiver Minutenreserve durch dezentrale Klein-KWK-Anlagen

Kurscheid, Eva Marie 05 January 2010 (has links) (PDF)
Ziel der Dissertation ist, die Bereitstellung positiver Minutenreserve durch dezentrale Klein-KWK-Anlagen unter technischen, wirtschaftlichen und ökologischen Gesichtspunkten zu bewerten. Die Grundlage einer solchen Bewertung bilden detaillierte Kenntnisse des Abrufverhaltens positiver Minutenreserve. Deshalb wird die Inanspruchnahme positiver Minutenreserve untersucht und als stochastischer Prozess modelliert. Auf dieser Basis erfolgen Betrachtungen zur Dimensionierung der Wärmespeicher, zum Netzbetrieb mit hoher Dichte dezentraler Klein-KWK-Anlagen und zur Wirtschaftlichkeit eines solchen Konzeptes. Die abschließende ganzheitliche Betrachtung liefert Hinweise zur optimalen Betriebsweise der Klein-KWK-Anlagen. / From the technical point of view, virtual power plants consisting of small decentralized co-generation plants are able to provide positive tertiary reserve power for the European electricity transmission grid. For serious analyses, detailed knowledge about the load-characteristic of called reserve power is essentially. In order to examine grid operation, heat storage capacity and optimized power plant operation, the switch-on times of co-generation plants and the co-generated heat during reserve power provision have to be estimated. Aiming this, the called positive tertiary reserve power in Germany is analyzed and a mathematical model of the call-characteristic is synthesized. Furthermore, the results of examining grid operation, optimizing heat storage capacity and power plant operation are given. Calls of positive tertiary reserve power usually occur suddenly, non-scheduled and jumpy. Sometimes, there are single calls. Usually, calls occur clustered, i.e. one call is directly followed by further calls. Positive reserve power is much higher frequented under peak-load conditions than under base-load conditions. The characteristic of calling positive tertiary reserve power deeply depends on the control area. From the mathematical point of view, a Poisson-process fits non-scheduled and jumpy occurring events. Each jump marks a call date of positive tertiary reserve power. The values of the called power fit a logarithmical normal distribution. The lengths of the call-clusters satisfactorily fit a geometrical distribution. The expected value of called reserve energy is modeled dependent from the time of the day. The model is essential for simulating all combinations of switch-on times of co-generation plants and of co-generated heat volumes that might occur during providing reserve power. Aiming to optimize the installed heat storage capacity, the quote of heat use has to be examined. From both technical and ecological point of view, installing large heat storages is desirable in order to use all co-generated heat. From the economical point of view, installing any heat storage is not sensible. The solution of this trade-off is installing a heat storage that guarantees less or equal CO2-emissions than a conventional power plant fired with natural gas. The results of this thesis lead to 1 kWh heat storage capacity per 1 kW installed electrical power as rule of thumb. Concerning grid operation in steady state, a much higher density of co-generation plants than expected is technically installable. A general rule for extending the installable decentralized power cannot be deducted. Examining economics, decentalized co-genertation plants are desired to provide balancing power during their stand-by times. Building a virtual power plant only in order to provide reserve power is not economically sensible. From the power plant owners' view, providing positive tertiary reserve power by small decentralized co-generation plants is generally sustainable.
326

Pilotprojekt zur Optimierung von großen Versorgungssystemen auf Basis der Kraft-Wärme-Kältekopplung mittels Kältespeicherung

Urbaneck, Thorsten, Platzer, Bernd, Schirmer, Ulrich, Uhlig, Ulf, Göschel, Thomas, Baumgart, Gunter, Fiedler, Gunter, Zimmermann, Dieter, Wittchen, Falk, Schönfelder, Veit 01 March 2010 (has links) (PDF)
In einem Vorprojekt wurde die Machbarkeit der Kältespeicherung untersucht und positiv bewertet. Obwohl in der Bundesrepublik Deutschland bis 2007 noch kein großtechnischer Kurzzeit-Kältespeicher existierte, haben die Stadtwerke Chemnitz AG einen Speicher erfolgreich errichtet. Seit 2007 ist dieser Kaltwasserspeicher in Betrieb. Die Professur Technische Thermodynamik der TU Chemnitz übernahm bei diesem Verbundforschungsvorhaben die Begleitforschung (Forschung, Entwicklung, Beratung, Überwachung). Es wurde demonstriert, dass große Kältespeicher energetische, ökologische und ökonomische Vorteile bewirken können. Diese Vorteile kann man nutzen, um die Kraft-Wärme-Kälte-Kopplung zu stärken. Neben dem höheren Einsatz von Abwärme aus der Kraft-Wärme-Kopplung, ist die Reduktion des Elektroenergiebedarfs und die Begrenzung von Lastspitzen von besonderer energiewirtschaftlicher Bedeutung. Folgeprojekte in Deutschland zeigen die Akzeptanz dieser Technik. Dieser Bericht liefert eine Beschreibung des Systems und die Ergebnisse des Verbundvorhabens. Der Schwerpunkt liegt dabei auf der Auswertung des Betriebs von 2007 bis 2009. Das zugrunde liegende Monitoringprogramm lieferte hierfür die entsprechenden Messwerte.
327

From recovery boiler to integration of a textile fiber plant : Combination of mass balance analysis and chemical engineering

Magnusson, Hans January 2015 (has links)
Modern chemical technology is an efficient tool for solving problems, particularly within the complex environment of the pulp and paper industry, and the combination of experimental studies, mill data and mass balance calculations are of fundamental importance to the development of the industry. In this study various examples are presented, whereby chemical technology is of fundamental importance. It is well documented that under normal conditions the molten salt mixture from the kraft recovery boiler flows down into the dissolving tank without problems. However, in the case of  alternatives to the kraft recovery boiler, knowledge of more precise data of the molten salts is required for the design calculations. In this study the viscosity for the case of sodium carbonate and 30 mole% sulphide has been measured and is of the magnitude 2 – 3 cP at temperatures relevant for a recovery boiler, i.e. similar to water at room temperature. The presence of non-process elements (NPE) in a typical pulp mill has been investigated. The main input is with regards to the wood, and anticipated problems include; deposits in evaporators, high dead-load in liquor streams, plugging of the upper part of the recovery boiler and decreasing efficiency in the causticization department. Efficient green liquor clarification is of the greatest importance as an efficient kidney for many NPE. Mill data and calculations show that the magnesium added in the oxygen delignification does not form a closed loop. Integration of a prehydrolysis kraft pulp mill producing dissolving pulp with a plant producing viscose textile fiber could be highly beneficial. The prehydrolysis liquor will contain both sugars and acetic acid. It is however not possible to fully replace the sulphuric acid of the viscose spinning bath with acetic acid of own production. The sulphuric chemicals from the viscose plant can be partly taken care of in the kraft recovery area as well as the viscose plant which can be supplied with alkali and sulphuric acid. Zinc-containing effluents from the viscose plant can be treated with green liquor to precipitate zinc sulphide. / Modern chemical technology is an extremely efficient tool for solving problems particularly in a complicated environment such as the pulp and paper industry. Here, examples are studied during which chemical technology is of fundamental importance. At normal conditions the molten salt mixture from the kraft recovery boiler flows down into the dissolving tank without hindrance. However, for certain kraft recovery boiler alternatives, knowledge of more precise data of the molten salts is required. The viscosity for the case of sodium carbonate and 30 mole% sulphide has been measured and is of the magnitude 2 – 3 cP at relevant temperatures. The main input of non-process elements (NPE) is down to the wood, and known problems include deposits in evaporators and decreasing efficiency in the causticization department. Green liquor clarification is an efficient kidney for many NPE. Magnesium added in the oxygen delignification does not form a closed loop. Integration of a prehydrolysis kraft pulp mill producing dissolving pulp with a plant producing viscose textile fiber could be of significant interest, as the handling of both alkali and sulphuric compounds can be integrated. Problems will however arise as the capacity of the pulping line and the chemical recovery has to be adjusted.
328

Råder det diskrepans mellan 8 kap. 4 § UB och vissa EU-rättsliga förordningar som reglerar gränsöverskridande verkställighet av domar?

Danilovic, Branko January 2010 (has links)
Under 2000-talet har två EU-rättsliga förordningar stiftats i syfte att reglera erkännande och verkställighet av domar på privaträttens område inom EU. Först stiftades Bryssel I-förordningen. I enlighet med den förordningen kan en dom som meddelats av domstol i en medlemsstat verkställas i en annan medlemsstat. Dessförinnan skall domen förklaras verkställbar i den medlemsstat där verkställighet önskas. Den andra förordningen, EEO-förordningen, tillkom bara några år senare. I denna förordning har förfarandet varigenom en dom förklaras verkställbar i en annan medlemsstat avskaffats. Istället skall domen efter ansökan kunna intygas vara en europeisk exekutionstitel av domstolen i den medlemsstat där domen har meddelats. Med ett sådant intyg får domen därefter verkställas fritt i samtliga medlemsstater utan något mellanliggande förfarande. Förordningarna reglerar inte hur själva verkställigheten skall gå till. Verkställigheten skall ske i enlighet med den nationella lagstiftning i medlemstaten där verkställighet begärs. För svenskt vidkommande skall betalningsdomar verkställas genom utmätning. Enligt svensk rätt får verkställigheten inte slutföras förrän betalningsdomen vunnit laga kraft. Enligt EEO-förordningen å andra sidan får verkställigheten slutföras omedelbart. Det finns en någorlunda stor sannolikhet att en utländsk dom vinner laga kraft innan en verkställighetsförklaring gör detsamma. Enligt svensk rätt skulle det i sådant fall vara tillåtet att verkställa domen fullt ut medan reglerna i Bryssel I-förordningen inte skulle tillåta annat än vidtagande av säkerhetsåtgärder i ett sådant skede. Det är också möjligt att den svenska regeln om begränsningar i verkställigheten strider mot diskrimineringsförbudet i Amsterdamfördraget eller den allmänna principen om likabehandling. / During the last decade two EC Regulations have been adopted in order to regulate and introduce uniform standards for procedures regarding recognition and enforcement of judgements in civil and commercial matters within the EU. The first regulation to be adopted was the Brussels I Regulation. According to its provisions a judgement delivered in one Member State can be enforced in an other Member State. Previously the judgement must be declared enforceable in the Member State where the judgement is to be enforced. A few years later the second regulation called the EEO Regulation was adopted. According to the EEO Regulation a declaration of enforceability is not required anymore. Instead a judgement can be certified as a European Enforcement Order for uncontested claims by the court or a competent authority in the Member State where the judgement was delivered. The enforcement procedure itself shall however be governed by the law of the Member State of enforcement. In accordance with Swedish law a judgement concerning payment claims should be enforced by distraint. According to Swedish law a Debtor’s property is allowed to be seized but not retailed until time for an appeal has expired. The EEO Regulation on the other hand allows the enforcement procedure to be finalized immediately. There is a high probability that the time for an appeal against a foreign judgement may expire before such time in which an appeal against the declaration of enforceability can be lodged expires. In that case the Swedish law would permit the executor to finalize the enforcement procedure while in according to the Brussels I Regulation, the enforcement procedure in such case should still be limited to protective measures. It is also quite possible that the Swedish provision infringes the non-discrimination rule in the Treaty of Amsterdam or The General Principle of Equality.
329

Einfluss der Antiarrhythmika Flecainid und Amiodaron auf die kontraktile Funktion und die Kraft-Frequenz-Beziehung des Herzens / Influence of the antiarrhythmic drugs Flecainide and Amiodarone on the contractile function and the force-frequency-relationship of the heart

Pagel, Christian 09 August 2010 (has links)
No description available.
330

Kraft- und Drehmomentabgabe thermoplastisch geformter Schienen bei Frontzahnderotation vor und nach Alterungssimulation / Initial forces and moments delivered by removable thermoplastic appliances during rotation of an upper central incisor before and after simulated aging

Engelke, Benjamin 07 December 2010 (has links)
No description available.

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