Tallinn University of Technology

About: Tallinn University of Technology is a education organization based out in Tallinn, Estonia. It is known for research contribution in the topics: European union & Oil shale. The organization has 3688 authors who have published 10313 publications receiving 145058 citations. The organization is also known as: Tallinn Technical University & Tallinna Tehnikaülikool.

Technologies and Practical Implementations of Air-Conditioner Based Demand Response

Abstract: Nowadays, the most notable uncertainty for an electricity utility lies in the electrical demand of end-users. Demand response (DR) has acquired considerable attention due to uncertain generation outputs from intermittent renewable energy sources and advancements of smart grid technologies. The percentage of the air-conditioner (AC) load over the total load demand in a building is usually very high. Therefore, controlling the power demand of ACs is one of significant measures for implementing DR. In this paper, the increasing development of ACs, and their impacts on power demand are firstly introduced, with an overview of possible DR programs. Then, a comprehensive review and discussion on control techniques and DR programs for ACs to manage electricity utilization in residential and commercial energy sectors are carried out. Next, comparative analysis among various programs and projects utilized in different countries for optimizing electricity consumption by ACs is presented. Finally, the conclusions along with future recommendations and challenges for optimal employment of ACs are presented in the perspective of power systems.

Spectral heterogeneity of QuickBird satellite data is related to fine-scale plant species spatial turnover in semi-natural grasslands

Abstract: Question: Can satellite data be related to fine-scale species diversity and does the integrated use of field and satellite data provide information that can be used in the estimation of fine-scale species diversity in semi-natural grassland sites? Location: The Baltic Island of Oland (Sweden). Methods: Field work including the on-site description of 62 semi-natural grassland sites (represented by three 0.5m0.5m plots per site) was performed to record response variables (total species richness, mean species richness and species spatial turnover) and field-measured explanatory variables (field-layer height and distance between plots). Within each site, QuickBird satellite data were extracted from a standardized sample area by associating each field plot with a 33 pixel window (1 pixel = 2.4m2.4 m). Explanatory variables (the normalized difference vegetation index and spectral heterogeneity) were generated from the satellite data. Correlation tests, univariate regressions, variance partitioning and multivariate linear regressions were used to analyse the associations between response and explanatory variables. Results: There was a significant association between the spectral heterogeneity of the near-infrared band and the field-measured spatial turnover of species. The most parsimonious explanatory model for each response variable included both field-measured and satellite-generated explanatory variables. The models explained 30–35% of the variation in species diversity (total richness 36%, mean richness 31%, species turnover 33%). Conclusions: High spatial resolution satellite data are capable of supplying fine-scale habitat information that is relevant for the monitoring and conservation management of fine-scale plant diversity in semi-natural grasslands. (Less)

New Trends in the Analytical Theory of Long Sea Wave Runup

Abstract: A modern view on the analytical theory of the long sea wave runup on a plane beach is presented. This theory is based on rigorous solutions of nonlinear shallow-water equations. The dynamics of the moving shoreline is studied in detail. It is demonstrated that extreme characteristics of the runup process (runup and rundown amplitudes, extreme values of on- and off-shore velocities, and critical amplitude of the breaking wave) can be found using the solution of the linear shallow-water theory, meanwhile the description of the time series of the wave field requires the nonlinear theory. The key and novel results presented here are: i) parameterization of basic formulas for extreme runup characteristics for bell-shape waves, showing that they weakly depend on the initial wave shape, which is usually unknown in real sea conditions; ii) runup analysis of periodic asymmetric waves with a steep front, as such waves are penetrating inland over larger distances and with greater velocities than symmetric waves.