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- Jägerbrand, Annika K.
(author)
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Level of knowledge of sustainable development (SD) in the master’s program Sustainable Building Information Management (BIM)
- 2024
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Other publication (other academic/artistic)abstract
- Sustainable development (SD) is essential to reduce and mitigate climate change impacts, environmental deterioration and to increase social sustainability. SD is therefore highly relevant for the engineering profession and is today found integrated with the higher education of specific engineering programs. This paper investigated the knowledge of SD for students entering the master’s program in Sustainable Building Information Management (BIM) by comparing levels of knowledge at the start and end of the first course Sustainability, Analyses and Simulations. The level of knowledge of SD was analyzed by classifying students’ conceptions of sustainability using SOLO taxonomy and the spectrum of liminality and the threshold concept. Students written responses to the question “What do you know about sustainability?” and written group project reports were used for analyzing levels of knowledge of SD. Levels of knowledge of SD was classified as pre (pre-liminal or pre-structural); uni-structural, multi-structural, relational and post-stages (extended abstract or post-liminal). In total, 68% of the students entering the master’s program in 2017 and 88% in 2018 showed a pre-structural, uni-structural and multi-structural SD knowledge. In general, few students entering the program showed relational and post-stages of SD knowledge, 32% and 12% of the students in 2017 and 2018, respectively. The students at the post-stage were able to express themselves more individually and creatively compared to previous levels in that they could connect the dimensions of SD to the context of SD of buildings, but also argue why SD of buildings was important and they could also suggest actions or tools for improved SD that engineers should use. Only one group of five (in 2017) showed a post-stage level of knowledge in the group project report. It is likely that the student’s general approach to the work with the reports was to mainly cope with the course requirements which is a sign of surface approach to learning. It, therefore, seems reasonable that future developments of the course should ensure that the students use the scientific literature in their group project reports to make it easier for them to understand the relationship between software use and the connection to green buildings certificate systems and SD of buildings. By making it mandatory to include scientific literature in the reports the students will be encouraged to read and think critically, and deeper, and to put the practical implementation of the software analysis results into a scientific context of SD and BIM.
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| 4. |
- Ahmad, Bilal, et al.
(author)
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The Perfect Match : RIS-enabled MIMO Channel Estimation Using Tensor Decomposition
- 2023
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Other publication (other academic/artistic)abstract
- The deployment of reconfigurable intelligent surfaces (RISs) in a communication system provides control over the propagation environment, which facilitates the augmentation of a multitude of communication objectives. As these performance gains are highly dependent on the applied phase shifts at the RIS, accurate channel state information at the transceivers is imperative. However, not only do RISs traditionally lack signal processing capabilities, but their end-to-end channels also consist of multiple components. Hence, conventional channel estimation (CE) algorithms become incompatible with RIS-aided communication systems as they fail to provide the necessary information about the channel components, which are essential for a beneficial RIS configuration. To enable the full potential of RISs, we propose to use tensor-decomposition-based CE, which facilitates smart configuration of the RIS by providing the required channel components. We use canonical polyadic (CP) decomposition, that exploits a structured time domain pilot sequence. Compared to other state-of-the-art decomposition methods, the proposed Semi-Algebraic CP decomposition via Simultaneous Matrix Diagonalization (SECSI) algorithm is more time efficient as it does not require an iterative process. The benefits of SECSI for RIS-aided networks are validated with numerical results, which show the improved individual and end-to-end CE accuracy of SECSI.
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| 5. |
- Alatalo, Juha M., et al.
(author)
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Seven years of experimental warming and nutrient addition causes decline of bryophytes and lichens in alpine meadow and heath communities
- 2024
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Other publication (other academic/artistic)abstract
- Global change is predicted to have large and rapid impact on polar and alpine regions. Bryophytes and lichens increase their importance in terms of biomass, carbon/nutrient cycling, cover and ecosystem functioning at higher latitudes/altitudes. Here we report from a seven year factorial experiment with nutrient addition and warming on the abundance of bryophytes and lichens in an alpine meadow and heath community. Treatments had significant negative effect on relative change of total abundance bryophytes and lichens, the largest decline to the nutrient addition and the combined nutrient addition and warming treatments, bryophytes decreasing most in the meadow, lichens most in the heath. Nutrient addition, and the combined nutrient addition and warming brought rapid decrease in both bryophytes and lichens, while warming had a delayed negative impact. Of sixteen species that were included the statistical analyses, we found significant negative effects on seven species. We show that impact of simulated global change on bryophytes and lichens differ in in time and magnitude among treatments and plant communities. Our results underscore the importance of longer-term studies to improve the quality of climate change models, as short-term studies are poor predictors of longer-term responses of bryophytes and lichens, similar to what have been shown for vascular plants. Species-specific responses may differ in time, and this will likely cause changes in the dominance structures of bryophytes and lichens over time.
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| 7. |
- García Martín, Eva, et al.
(author)
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Hoeffding Trees with nmin adaptation
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Other publication (other academic/artistic)abstract
- Machine learning software accounts for a significant amount of energy consumed in data centers. These algorithms are usually optimized towards predictive performance, i.e. accuracy, and scalability. This is the case of data stream mining algorithms. Although these algorithms are adaptive to the incoming data, they have fixed parameters from the beginning of the execution, which lead to energy hotspots. We present dynamic parameter adaptation for data stream mining algorithms to trade-off energy efficiency against accuracy during runtime. To validate this approach, we introduce the nmin adaptation method to improve parameter adaptation in Hoeffding trees. This method dynamically adapts the number of instances needed to make a split (nmin) and thereby reduces the overall energy consumption. We created an experiment to compare the Very Fast Decision Tree algorithm (VFDT, original Hoeffding tree algorithm) with nmin adaptation and the standard VFDT. The results show that VFDT with nmin adaptation consumes up to 89% less energy than the standard VFDT, trading off a few percent of accuracy. Our approach can be used to trade off energy consumption with predictive and computational performance in the strive towards resource-aware machine learning.
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| 8. |
- Habimana, Olivier
(author)
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Asymmetric Nonlinear Mean Reversion in Real Effective Exchange Rates : Evidence from Sub-Saharan Africa
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Other publication (other academic/artistic)abstract
- This paper evaluates the purchasing power parity (PPP) theory in a panel of Sub-Saharan African (SSA) countries. The study applies unit root tests that are based on exponential smooth transition autoregressive (ESTAR) models to account for nonlinearities and asymmetries in real exchange rate adjustment towards its equilibrium (mean) value. Nonlinearities and asymmetries are very relevant for these countries and are potentially due to transaction costs, trade barriers and other market frictions, and frequent official interventions in the foreign exchange market. Results indicate that once nonlinearities and asymmetries are taken into account there is more empirical support for the PPP theory in SSA.
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- Habimana, Olivier
(author)
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Do flexible exchange rates facilitate external adjustment? A dynamic approach with time-varying and asymmetric volatility
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Other publication (other academic/artistic)abstract
- This paper revisits the claim that flexible exchange rates facilitate external adjustments, in a panel of emerging market and developing economies. In contrast to previous studies which mainly use the exchange rate regime classification as a proxy for exchange rate flexibility, the present study estimates a measure of exchange rate flexibility that considers autoregressive conditional heteroskedasticity (ARCH) effects and possible asymmetric responses of the exchange rate to shocks. Generalized method of moments (GMM) estimators are employed to estimate the dynamic relationship between exchange rate flexibility and the speed of current account adjustment. The results suggest that more flexible exchange rates are associated with faster adjustment of current account imbalances, and when the possibility of an asymmetric response of exchange rate to shocks is taken into account, the estimated speed of adjustment is even higher.
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| 10. |
- Habimana, Olivier
(author)
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Wavelet multiresolution analysis of the liquidity effect and monetary neutrality
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Other publication (other academic/artistic)abstract
- This paper employs wavelets to examine the relationship between money, interest and output on a scale-by-scale basis using data for the US and Sweden during 1985-2017. First, series are decomposed into orthogonal timescale components using the discrete wavelet transform (DWT) together with the Daubechies least asymmetric wavelet filter, and then causality analysis (in the Granger sense) is performed at each scale of variations. The dynamics at the finest scale of one-year movements indicate that interest rate and real output respond to movements in the quantity of money. At horizons of four years and above, there is a feedback mechanism. This pattern is very similar in both countries at the mentioned scales and suggests that monetary disturbances have significant real effects and these effects last longer than is assumed in pure real-business cycle models. Further, a locally weighted regression analysis suggests that not only are the direction and strength of the relationship among these variables scale-dependent but also the shape of the relationship may change from one scale to another. This method suggests a negative relationship between money and the short-term interest rate, as predicted by the liquidity preference theory, at cycles of one to four-year periods. Overall, these findings highlight the relevance of timescale decomposition in macroeconomic analysis.
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