University of Siegen
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Publication Access status: Open Access , Mörtel für die Erhaltung historischer Kalkputze : Haftmörtel, Hinterfüllmörtel und Kalkputze(1997)Im Rahmen der Dissertation wurde ein Mörtelsystem für die Restaurierung historischer Kalkputze entwickelt. Die Literaturübersicht dieser Dissertation befaßt sich mit Ursachen für Schäden an Putzen, dabei wird ausführlich auf herstellungsbedingte Fehler eingegangen und chemische, physikalische und mikrobiologische Gründe für die Entstehung von Putzschäden behandelt. Ausführlich werden mögliche Schäden durch ungeeignete Restaurierungsmörtel behandelt, die z. B. Alkalisalze eintragen, aber auch Ettringit- und Thaumasitbildung durch Reaktionen mit Sulfaten in historischen Mörtel verursachen können. Ein bedeutender Teil der Dissertation widmet sich der Untersuchung von historischen Putzen der Torhalle in Lorsch, der Einhardbasilika in Steinbach, des Magdeburger Domes und des ehemaligen Zisterzienserklosters Heydau in Morschen. Die Eigenschaften dieser Putze werden umfangreich nicht nur hinsichtlich ihrer Mörtelzusammensetzung und ihrer mechanischen Eigenschaften, sondern auch ihrer hygrischen Eigenschaften (Wasseraufnahme, Wasserabgabe, Wasserdampf-Diffusionswiderstand), ihrer Porenstruktur und Phasenausbildung geprüft. Die gewonnenen Daten dienten zur Definition von Anforderungsprofilen für Restaurierungsmörtel, die zum einen den historischen Bestand sichern (Haftmörtel, Hinterfüllmörtel), zum anderen als Ersatzmörtel bei Fehlstellen dienen (Kalkputze) sollen. Die verschiedenen Mörtel sollen die folgenden Aufgaben bei einer Restaurierung übernehmen: - Haftmörtel sollen vor der Verfüllung hohlliegender Putzbereiche zu deren Randsicherung und zum Wiederbefestigen lockerer Putzschollen dienen und mechanisch wieder leicht entfernbar sein, ohne die Altsubstanz zu schädigen. - Hinterfüllmörtel dienen zum Verfüllen hohlliegender Putzpartien, die im Anschluß an die Maßnahme wieder einen ausreichenden und dauerhaften Verbund mit dem Untergrund aufweisen sollen. Sie können drucklos mit Spritzen eingebracht werden und müssen ein gutes Penetrationsvermögen aufweisen, damit alle Hohlräume sicher gefüllt werden. - Kalkputze entweder auf Basis von Sandkalk (mit feuchtem Sand trocken gelöschter Branntstückkalk) oder auf Basis handelsüblichen Weißkalkhydrates (WKH) sollen, möglichst exakt den historischen Vorbildern nachgestellt, als Ersatz für abgängigen historischen Putz eingesetzt werden.Source Type:Book6 9 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Open Access , Realisierung eines Mehrkammer-Depositionssystems zur kontinuierlichen photovoltaischen Beschichtung flexibler Substrate(1999)In the course of the work presented a deposition system on laboratory scale for the fabrication of amorphous hydrogenated silicon (a-Si:H) solar cells has been designed and constructed. The system consists of seven metal sealed UHV stainless steel chambers which are linked by pressure stages. The pressure stages between the deposition zones allow pressure gradients of more than 1:1000 between adjacent chambers. In the first two zones TCO ( T ransparent C onductive O xide: with sheet resistances from R sq =9±2Ω (ITO) and R sq =13±7Ω (ZnO) on a 9 by 9cm 2 glass substrate with an average transmission of 84% within the spectral range of 450nm-850nm.) and metal contacts are deposited by rf magnetron sputtering whereas two of the other zones are used for the deposition of the a-Si:H layers. In the fifth zone a laser patterning system can be coupled in. Subsequent to the test phase of all single components they are examined as a whole system. A-Si:H solar cells are produced on continuous flexible metal tapes (75m by 0.09m). For the first time it became possible to handle sputter and PECVD processes simultaneously as well as the parallel deposition of doped and intrinsic a-Si:H layers in one single vacuum chamber. This parallel processing allows the mass production of solar cells in a reel to reel in line system on long continuous tapes. The developed resulting stop and go mode can easily be applied to a continuous movement since the substrate is not fixed. Only extensions of the plasma zones according to film thickness and deposition rate are necessary. In competition to solar cells produced by separate deposition the initial efficiencies of solar cells obtained by parallel processing constantly range at over 6.7% (A=0.785cm 2 ).Source Type:Doctoral Thesis2 5 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Open Access , Methoden zur Reduzierung dynamischer Gemischfehler(1998)The improvement of the exhaust emissions of internal combustion engines is one of the most important challenges for the development of software for electronic control units. To operate the catalyst with high efficiency the air/fuel ratio (AFR) has to be exactly controlled in every operation point of the engine. At steady state (constant speed and torque) this can be realized in most cases with a closed loop lambda control. But in transient operation, additionally control functions are required in order to take consideration into the thermodynamic phenomenology of the air path and the fuel path of an IC-Engine. In response model based controllers have recently been developed for the compensation of the main thermodynamic effects in the manifold. However, these controllers are mostly open loop controllers with poor robustness against parameter variations. The main emphasis of this work is the design of new transient AFR-control strategies using linear and nonlinear Kalman-Filters. The realized strategy includes the determination of the in-cylinder air masses, the reduction of the effects from dead times in the fuel path and the compensation of the wall wetting dynamics. One elementary part is the development of control oriented physical models for the air path and the fuel path. Instead of using only mean value models for the air path, also event based deterministic perturbations (pulsations) were modeled with signal theory techniques. This perturbations are together with the nonlinear filling behavior of the manifold mostly the reason of a speed dependency during parametration of throttle models [Sche-1]. Load transients are able to cause temperature transients in the manifold of more than 30°C. This behavior is modeled and verified with vehicle experiments. The wall wetting dynamics are modeled with a second order lag with feed through term. The two time constants in this model are corresponding to the wall film dynamics and the valve film dynamics. If the engine is not operated at the stochiometric point the balance of controlled and measured air/fuel ratio changes with the rate of residual gas. This effect can easily be used to determine the residual gas ratio in the engine by comparing controlled and measured AFR. For a speed-density injection system an adaptive Extended Kalman-Filter was used to estimate the air masses in the cylinders. With an additional adaptive parameter for throttle tolerances, the algorithm is not only able to handle strong intake parameter variations but it can also identify air leakage in the manifold. The Kalman-Filter operates in crank angle domain and therefore the frequency of the considered perturbations is kept constant. The algorithm delivers high dynamic manifold pressure and temperature information and the air mass flow in and out of the manifold with small perturbations. Furthermore the methodology of sensor data fusing is applied to the application of air mass estimation also by using an Extended Kalman-Filter [Sche-3]. If several sensors are available that deliver information about a desired value the sensor data fusing algorithm combines the sensor signals and weights them dependent on a stochastic model. This kind of algorithm delivers very reliable estimates using redundant information. To reduce the effects of dead times in the fuel path (time between air mass calculation and closing of the intake valve) an air mass predictor was developed. In a first step this algorithm predicts the effective area of flow by assuming the throttle variation with a colored noise process. In a second step the predicted cylinder air masses are calculated with the results of the throttle predictor by using a free running air path model. Especially during engine start and at low temperatures the wall wetting dynamics have strong effects on AFR. Open loop dynamic compensators are often realized by using the model matching method. However this controllers have poor robustness in case of variations of the dynamic parameters. With a state space controller and observer the robustness can essentially be increased by using feedback from an Universal Exhaust Oxygen Sensor .Source Type:Doctoral Thesis1 7 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Open Access , Auswertung direkter Brennrauminformationen am Verbrennungsmotor mit estimationstheoretischen Methoden(1999)The estimation of the air mass in the cylinder of a spark ignition (SI) engine is crucial in order to regulate the exact air fuel (A/F) ratio for the catalyst and thus minimize the emissions. In this work, new sensors, which provide cylinder individual information are investigated and the air mass in each individual cylinder is calculated with adaptive, model based algorithms. When the estimation of the air mass in the cylinder is performed by a combustion pressure signal there is a necessity to eliminate the disturbances in the pressure signal. Therefore, a linear Kalman-Filter for the determination of the absolute cylinder pressure value has been developed. The algorithm is able to filter the combustion pressure signal during runtime and to determine the variable offset provoked by the thermal shock. Through a sensitivity analysis of the parameters of the physically based model, the temperature of the A/F mixture has been identified as the parameter which influences mainly the estimation result and is difficult to determine. As a result, an adaptive Kalman-Filter algorithm has been derived that estimates the cylinder individual air mass from measured cylinder pressure and adapts the temperature of the A/F mixture through the lambda-sensor signal. The algorithm has been tested with measured vehicle data, implemented in a prototype engine control unit with the following results. The deviation in the lambda-sensor signal is in the size of the mass electronic control unit and even better. This has been achieved with a pure model based algorithm without calibration on the testbed or in the vehicle. The advantage of the estimation of the air mass on the basis of measured cylinder pressure signals can be seen in the cylinder individual determination of the air mass, the exclusion of conventional faults like air leakage and throttle faults, the high redundancy for reliability and diagnostic concepts and by rendering the determination of the volumetric efficiency superfluous. In addition, there are enormous possibilities for the realisation of cylinder individual engine functions such as knock and spark angle control.Source Type:Doctoral Thesis524 305 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Open Access , Online-Demodulation stark gestörter winkelmodulierter Signale mit dem Extended Kalman-Filter(1999)Kalman filters offer a good opportunity for processing heavily disturbed signals. Applied to the demodulation problem of communications an Extended Kalman filter is used as a demodulator of angularly modulated signals. In the range of low signal to noise ratios (0 to 17 dB) a number of several filter models is examined in this work /3, 5, 16, 24, 34, 35, 40, 42, 49, 54, 69, 77/. The two quadrature components, real and imaginary part of a received signal in the baseband are considered as components of a two dimensional observation vector from which phase, frequency and even amplitude and amplitude derivative are estimated. Supplementary observations as amplitude and phase, adaptive elements and smoother elements have been tested in an online development environment. It has been built up with a DSP (TMS320 C44) to prove data fusion concepts and information absorption in Kalman filters based on examinations which have been theoretical determined in /5, 42/. It proves that even virtually created additional observations like phase and amplitude determined with the two quadrature components lead to an increase of the absorbed information, which leads to better filter results. Furtheron stability, accuracy and bandwidth have been observed in the online simulation. They are important criteria for online processing, whereas in case batch processing only the accuracy is the important parameter. Chapter 3 will be laying the basics in signal theory for the following chapter 4, where the different Kalman filter models developed for the demodulation problem will be described. Chapter 5 will show filtering results and Chapter 6 gives a rough description of the DSP development environment used for online-demodulation /2, 33, 76/. A summary in Chapter 7 concludes this work with results and remarks.Source Type:Doctoral Thesis4 8 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Open Access , 1 7