Energy efficient buildings by use of reinforced masonry walls : An experimental study

Användning av ytförstärkning har undersökts som ett led i att förbättra murade ytterväggars energiprestanda. De experimentella undersökningarna genomförda vid Lunds tekniska högskola visar att genom användning av ytförstärkning kan tjockleken på den bärande delen i en yttervägg minskas med mellan 30 - 50 procent jämfört med dagens väggtyper. Väggarnas bärförmågan kan samtidigt bibehållas eller rentav ökas. Det insparade utrymmet kan nyttjas till mer termisk isolering, vilket medför att ytterväggens energiprestande förbättras utan ytterligare ökning av dess totala tjocklek

Moisture content prediction of rain-exposed wood: Test and evaluation of a simple numerical model for durability applications

Abstract in FrenchDecay-prediction models can be used to predict the service life of wooden components. However, knowledge of how the material climate, i.e. moisture content and material temperature, varies with time is required. A reliable material climate prediction model is therefore crucial in situations when measurements are not viable. The aim of this paper is to develop and assess the performance of a simple numerical moisture transport model for rain-exposed wood. The main focus is on the influence of rain and moisture transport in the transversal direction.First, a model based on Fick’s second law of diffusion was calibrated against laboratory measurements where wooden boards were exposed to artificial rain. Second, the model was tested against field-test measurements on wooden boards in use-class 3.1, i.e. above-ground, exposed to rain and free to dry. The influence of rain was investigated by studying the difference between sheltered and exposed specimens over time. Finally, the model was applied to a number of Swedish climates and two different decay-prediction models were used to assess the output.The main conclusion is that the influence of rain can be reproduced with sufficient accuracy for the particular application. The error between the numerical result and measurements tends to increase with decreasing temperature and at high moisture contents. However, the total error is reduced when the moisture content history is post-processed in a decay-prediction model as the rate of decay decreases with decreasing temperature

Automatic robust estimation for exponential smoothing: Perspectives from statistics and machine learning

A major challenge in automating the production of a large number of forecasts, as often required in many business applications, is the need for robust and reliable predictions. Increased noise, outliers and structural changes in the series, all too common in practice, can severely affect the quality of forecasting. We investigate ways to increase the reliability of exponential smoothing forecasts, the most widely used family of forecasting models in business forecasting. We consider two alternative sets of approaches, one stemming from statistics and one from machine learning. To this end, we adapt M-estimators, boosting and inverse boosting to parameter estimation for exponential smoothing. We propose appropriate modifications that are necessary for time series forecasting while aiming to obtain scalable algorithms. We evaluate the various estimation methods using multiple real datasets and find that several approaches outperform the widely used maximum likelihood estimation. The novelty of this work lies in (1) demonstrating the usefulness of M-estimators, (2) and of inverse boosting, which outperforms standard boosting approaches, and (3) a comparative look at statistics versus machine learning inspired approaches

Autonomous Navigation With Ground Station One-Way Forward-Link Doppler Data

The National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC) has spent several years developing operational onboard navigation systems (ONS's) to provide real time autonomous, highly accurate navigation products for spacecraft using NASA's space and ground communication systems. The highly successful Tracking and Data Relay Satellite (TDRSS) ONS (TONS) experiment on the Explorer Platform/Extreme Ultraviolet (EP/EUV) spacecraft, launched on June 7, 1992, flight demonstrated the ONS for high accuracy navigation using TDRSS forward link communication services. In late 1994, a similar ONS experiment was performed using EP/EUV flight hardware (the ultrastable oscillator and Doppler extractor card in one of the TDRSS transponders) and ground system software to demonstrate the feasibility of using an ONS with ground station forward link communication services. This paper provides a detailed evaluation of ground station-based ONS performance of data collected over a 20 day period. The ground station ONS (GONS) experiment results are used to project the expected performance of an operational system. The GONS processes Doppler data derived from scheduled ground station forward link services using a sequential estimation algorithm enhanced by a sophisticated process noise model to provide onboard orbit and frequency determination. Analysis of the GONS experiment performance indicates that real time onboard position accuracies of better than 125 meters (1 sigma) are achievable with two or more 5-minute contacts per day for the EP/EUV 525 kilometer altitude, 28.5 degree inclination orbit. GONS accuracy is shown to be a function of the fidelity of the onboard propagation model, the frequency/geometry of the tracking contacts, and the quality of the tracking measurements. GONS provides a viable option for using autonomous navigation to reduce operational costs for upcoming spacecraft missions with moderate position accuracy requirements

Interaction of ethylbenzene and styrene with iron oxide model catalyst films at low coverages: a NEXAFS study

The adsorption of ethylbenzene and styrene on well ordered epitaxial iron oxide model catalyst films with different stoichiometries was investigated using near edge X-ray absorption fine structure spectroscopy (NEXAFS). On the iron-terminated Fe3O4(111) and a?Fe2O3(0001) surfaces a chemisorption of ethylbenzene and styrene is observed which initially occurs on the iron sites via the p-electron system of the phenyl ring. This forces the molecules into an almost flat lying configuration (h6 like ring adsorption geometry). In the case of ethylbenzene this adsorption complex is supposed to lead to an activation of the C-H bonds thus facilitating the dehydrogenation to styrene. The tilt angle of the aromatic ring systems increase to about 40° when approaching monolayer saturation. In contrast, the interaction with the oxygen-terminated FeO(111) surface is weak and of the physisorption type. The adsorbate-adsorbate interaction dominates and causes a tilted adsorption of the molecules from the beginning