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 & Computer science. The organization has 3688 authors who have published 10313 publications receiving 145058 citations. The organization is also known as: Tallinn Technical University & Tallinna Tehnikaülikool.

Integrated palaeoecological and historical data in the service of fine-resolution land use and ecological change assessment during the last 1000 years in Rõuge, southern Estonia

Abstract: Aims Our aim is to reconstruct decadal scale development of historical landscapes during the last 1000 years by means of fossil pollen analysis of annually laminated lake sediments, and detailed historical maps and documents. Location Lake Rouge Tougjarv (Estonia), a small lake with annually laminated lake sediments situated in a dense prehistoric setting. Methods The chronology of the palaeodata is based on the annual laminations supported by AMS 14C and 210Pb dating and 137Cs, 241Am, and spheroidal carbonaceous particle marker horizons. The time-scale and resolution allows fine sampling (the pollen samples generally comprise 3.5 years) and vegetation change reconstruction. Relevant source area of pollen (RSAP) of the lake was estimated, and the statistical zonation, rate of change, palynological richness, and DCA and PCA ordinations were generated on the basis of the pollen data. The historical calibration data set (maps, numerical information on population, domestic stock, farmland division, etc.) is based on archival material preserved in the Estonian Historical Archives. Results The topmost part (0–180 cm) of the sediment column of Lake Rouge Tougjarv, covering the last 1000 years, is visibly laminated carbonaceous gyttja. The varve chronology extends from ad 2000 to ad 1339, with a cumulative ± 9-year error estimate. Beyond this the chronology is extrapolated using the 14C date and varve age–depth estimations. The simulation of the RSAP of Lake Tougjarv shows that the major portion of the pollen loading originating from local vegetation is derived from plants growing within 2000 m of the sampling site. The pollen record divides into five statistically significant subgroups, which fall on the PCA plot into three clusters reflecting the general openness–closedness of the landscape. During the period between ad 1000 and 1200 (RT 1) the Rouge area was generally wooded with birch, spruce and pine forests. The advancement of extensive farming gradually opened up the landscape between ad 1200 and 1650 (RT 2 and RT 3). The maximum openness of the landscape was reached between ad 1650 and 1875 (RT 4), with the most open period in the late eighteenth century. Historical maps from 1684 and 1870–99 and available quantitative data on population, domestic stock, farmland division, etc. show the same trend. The pollen data covering the last 125 years, and maps from 1935 and 1995, show the reduction of arable land in RSAP of the lake under investigation and the reduction of open land to an extent comparable with the end of the seventeenth century. Main conclusions The formation and development of the cultural landscape at Rouge over the last 1000 years is characterized by rapid changes in floristic richness and rates of vegetation change attributed to certain historic processes in the RSAP. Five phases of landscape and social development are clearly distinguished during the last 1000 years. The decadal scale vegetation response to human-induced forcing agrees with historical maps and documents and could be used for past landscapes prior to the period with solid historical data.

Multi-Agent Systems and Blockchain: Results from a Systematic Literature Review

Abstract: Multi-Agent Systems (MAS) technology is widely used for the development of intelligent distributed systems that manage sensitive data (e.g., ambient assisted living, healthcare, energy trading). To foster accountability and trusted interactions, recent trends advocate the use of blockchain technologies (BCT) for MAS. Although most of these approaches have only started exploring the topic, there is an impending need for establishing a research road-map, as well as identifying scientific and technological challenges in this scope. As a first necessary step towards this goal, this paper presents a systematic literature review of studies involving MAS and BCT as reconciling solutions. Aiming at providing a comprehensive overview of their application domains, we analyze motivations, assumptions, requirements, strengths, and limitations presented in the current state of the art. Moreover, discussing the future challenges, we introduce our vision on how MAS and BCT could be combined in different application scenarios.

Parameters Identification and Modeling of High-Frequency Current Transducer for Partial Discharge Measurements

Abstract: Rogowski coil (RC) is a low-cost, air-cored, and flexible induction sensor for nonintrusive condition monitoring and thus can be used in a variety of applications. In this paper, a lumped parameter model of RC is presented and an experiment-based methodology is developed to determine its parameters. The performance of the RC is analyzed for detection and measurement of high-frequency (pulsed) signals such as partial discharge (PD) current pulses. A simple and efficient technique of numerical integration is adopted to avoid the conventional type of expensive and complex design analogue integrators. RC is modeled and simulated in the alternative transient program-electromagnetic transient program environment. The designed coil is tested to measure PDs in the laboratory. Simulated and experimental performance of RC is compared with a high-frequency current transformer. This comparison shows a good match and, hence, validates the design of RC for PD applications.