Optimising Parameters in Recurrence Quantification Analysis of Smart Energy Systems

Recurrence Quantification Analysis (RQA) can help to detect significant events and phase transitions of a dynamical system, but choosing a suitable set of parameters is crucial for the success. From recurrence plots different RQA variables can be obtained and analysed. Currently, most of the methods for RQA radius optimisation are focusing on a single RQA variable. In this work we are proposing two new methods for radius optimisation that look for an optimum in the higher dimensional space of the RQA variables, therefore synchronously optimising across several variables. We illustrate our approach using two case studies: a well known Lorenz dynamical system, and a time-series obtained from monitoring energy consumption of a small enterprise. Our case studies show that both methods result in plausible values and can be used to analyse energy data

Vulnerability Assessment of Settlements During Emergencies

During emergencies which occur as a result of uncontrolled effects of natural disasters, major technical and technological accidents and major epidemics of infectious diseases, the health and life of people and the persistent environmental degradation may be affected. Therefore, it is necessary to assess the vulnerability of the settlements from natural disasters and other accidents. The assessment must be professionally and scientifically established with a multidisciplinary approach. This paper defi nes methodology for vulnerability assessment of given populated areas during emergencies arising from uncontrolled effects of natural and other disasters which involves a complex analysis of actual hazard probabilities and the level of impact on humans, animals, property, cultural wealth, and the environment

Evaluation of placebo-adjusted cough on angiotensin-converting-enzyme inhibitors and hyperkalemia on mineralocorticoid-receptor-antagonists in patients with cardiovascular disease

Studies on the treatment with drugs like angiotensin-converting-enzyme inhibitors (ACE-Is) and mineralocorticoid-receptor-antagonists (MRAs) have achieved evidence for their beneficial effects on cardiac events in patients with cardiovascular diseases like arterial hypertension, coronary heart disease and heart failure. However, real-world data like those from numerous registries consistently show that patients are undertreated with these drugs. One of the reasons for inadequate treatment in recommendations are concerns of physicians regarding adverse events (AE) accompanied by the use of these drugs, such as cough on ACE-Is and hyperkalemia on MRAs, due to a widespread opinion that AE are always the causally related to these drugs. In a considerable number of patients enrolled in controlled clinical trials with these drugs cough and hyperkalemia occurred also on placebo. We addressed the question whether the “true” rates of cough on ACE-Is and hyperkalemia on MRAs are overestimated or other often unrecognized causes are underestimated, because the rate of these AE on placebo are usually not been taken into consideration. This is of particular clinical importance, since withholding or interruption of ACE-I and/or MRA application may be associated with a worse prognosis and other causes may be underdiagnosed. We included all eligible randomized, placebo-controlled trials with ACE-Is and MRAs in patients with cardiovascular disease where events of interest (cough on ACE-I and hyperkalemia on MRA) were adequately reported. Database PUBMED and Cochrane library were searched for eligible trials. To avoid any relevant study to be missed, we crosschecked the identified studies with those referenced in the current European Association of Cardiology guidelines for arterial hypertension, acute myocardial infarction with and without ST-segment elevation and heart failure. We determined placebo-adjusted rates of cough on ACE-Is and of hyperkalemia on MRAs, which present the attributable fraction of total cough/hyperkalemia rate in the exposed individuals that can be attributed specifically to the exposure. Placebo-adjusted rate of AE on drug (%) was calculated as the difference between the rates of AE in patients on drug and those on placebo, divided by the total rate of AE on drug. Example for cough on ACEIs: placebo-adjusted drug-cough = (drug-cough – placebo-cough) / drug-cough. This analysis was based on the assumption that incidence of specific AE on placebo represents spontaneous rate of AE in populations with cardiovascular disease. According to our analysis, a relevant number of cough cases on ACE-Is and hyperkalemia cases on MRAs might not be caused due to the treatment with these drugs, as placebo-adjusted rate for cough was 37% and for hyperkalemia 54%. In hypothetical worst-case scenario, which means withdrawal of ACE-I from all patients with cough and MRA from patients with hyperkalemia, about half of patients with cough (63%) on ACE-Is and with hyperkalemia (46%) on MRAs would not receive these life-saving therapies due the misconception that all cases of these AE are exclusively caused by these drugs. In turn, other causes of AE, might remain underdiagnosed. This study highlights the importance of a comprehensive approach in excluding other potential causes for cough on ACE-Is and hyperkalemia on MRAs in this population of patients before withdrawal of these drugs in order to avoid undertreatment with these well proven and beneficial drugs.Medikamente wie Angiotensin-Converting-Enzym (ACE) Hemmer und Mineralocorticoid-Rezeptor-Antagonisten (MRA) sind bedeutsam für die Verhinderung kardialer Ereignisse wie Tod oder Hospitalization bei Patienten mit kardiovaskulären Erkrankungen wie arterielle Hypertonie, koronare Herzkrankheit und Herzinsuffizienz. Daten aus zahlreichen Registern zeigen, dass Patienten mit diesen Substanzen erheblich untertherapiert und unterdosiert behandelt werden. Das liegt unter anderem darin, dass diese Arzneimittel abgesetzt werden, wenn unerwünschten Nebenwirkungen (UN) wie Husten bei ACE-Hemmern oder Hyperkaliämie bei MRA auftreten. Häufig geschieht dies aus Angst von schwerwiegenden Wechselwirkungen wie Hyperkaliämie. Bei einer beträchtlichen Zahl von Patienten traten die Husten und Hyperkaliämie in kontrollierten klinischen Studien zu diesen Medikamenten auch unter Placebo auf. Wir haben uns die Frage gestellt, ob die Nebenwirkungsrate bei ACE-Hemmern und Hyperkaliämie bei MRA als spezifische Ursachen überschätzt sind, da diesen UN mit Placebo ebenfalls vorkommen. Das ist von besonderer klinischer Bedeutung, da die Nicht-Therapie oder das Absetzen der ACE-Hemmer und/oder MRA insbesondere bei Patienten mit Herzinsuffizienz mit einer schlechteren Prognose assoziert ist und die eigentliche Ursache von Husten und Hyperkaliämie häufig nicht abgeklärt werden. Wir schlossen alle geeigneten randomisierten, placebokontrollierten Studien mit ACE-Hemmern und MRA bei Patienten mit kardiovaskulären Erkrankungen in eine Metaanalyse ein, bei denen Ereignisse von Interesse (Husten bei ACE-Hemmer und Hyperkaliämie bei MRA) adäquat berichtet wurden. Die Datenbank PUBMED sowie Cochrane-library wurden nach geeigneten Studien durchgesucht. Zusätzlich wurden alle Studien, die in den aktuellen Leitlinien der Europäischen Gesselschaft für Kardiologie für arterielle Hypertonie, akuten Myokardinfarkt und Herzinsuffizienz aufgenommen wurden, erfasst. Wir ermittelten die Placebo-adjustierte Rate für Husten bei ACE-Hemmern und Hyperkaliämie bei MRA, die den zuzurechnenden Anteil an Husten / Hyperkaliämie bei exponierten Personen darstellten, die spezifisch auf die Exposition zu bestimmten Medikamenten zurückzuführen sind. Die Placebo-adjustierte Rate von UN bei Medikamenten (%) wurde definiert als Differenz zwischen den Raten von UN bei Patienten der Medikamenten-Gruppe und Placebo-Gruppe, dividiert durch die Gesamtrate von UN der Medikamenten-Gruppe. Dieses Beispiel für Husten bei ACE-Hemmern erläutert das Vorgehen: Placebo-adjustierter Husten der Medikamenten-Gruppe% = (Medikament-Gruppe Husten% - Placebo-Gruppe Husten%) / Medikament-Gruppe Husten%. Die vorgelegte Analyse konnte zeigen, dass eine relevante Anzahl von Husten- und Hyperkaliämie-Fällen bei ACE-Hemmern bzw. bei MRA nicht allein durch die Wirkung dieser Medikamenten erklärt werden konnte, da die placebokorrigierte Rate für Husten 37% und für Hyperkaliämie 54% betrug. Dies würde in einem hypothetisch schlimmsten Fall zu Folge haben, dass etwa die Hälfte der Patienten mit Husten (63%) bei ACE-Hemmern und mit Hyperkaliämie (46%) bei MRA diese lebensverlängerde Therapie, nicht erhalten würden. Dies basiert auf der falschen Annahme, dass die Genese dieser UN in jedem einzelnen Fall ausschließlich durch die Wirkung dieser Medikamenten zu erklären sind, wodurch die wahren Ursache nicht diagnostiziert bleiben. Unsere Analyse zeigt, dass das Absetzen von diesen lebensrettenden Medikamenten vor allem bei Patienten mit Herzinsuffizienz nicht vorgenommen werden sollte. Die Leitlinie empfehlen, die kurzfristige Unterbrechung der Therapie, bevor die Ursache der Entstehung von UN eindeutig abgeklärt ist

Electric vehicles and low-voltage grid: impact of uncontrolled demand side response

The authors are looking at the impact of electric vehicles (EV) charging from low-voltage (LV) networks. Based on the data obtained from two different pilot projects: (i) Mini-E trial where EV users were incentivised to charge during the night; (ii) My Electric Avenue trial, where there were no similar incentives, authors want to quantify the impact of EV charging, presuming that the number of home-charging EV users will increase significantly in the near future. By assuming that the current load at individual household level is known or inferred, simulations are performed to estimate the future load. The authors look at different percentages of EV uptake and model clustered scenarios, where the social networking effect is imposed – users adopt an EV with a higher probability if their neighbour already has one. Simulations demonstrate that incentivising night-time charging can create large new peaks during the night, which could have negative effects on LV networks. On the other hand, simulations based on the data with no incentives shows that naturally occurring diversity in charging behaviour does not automatically result in comparable network stress at the same penetrations

Connectivity measures for internet topologies.

The topology of the Internet has initially been modelled as an undirected graph, where vertices correspond to so-called Autonomous Systems (ASs),and edges correspond to physical links between pairs of ASs. However, in order to capture the impact of routing policies, it has recently become apparent that one needs to classify the edges according to the existing economic relationships (customer-provider, peer-to-peer or siblings) between the ASs. This leads to a directed graph model in which traffic can be sent only along so-called valley-free paths. Four different algorithms have been proposed in the literature for inferring AS relationships using publicly available data from routing tables. We investigate the differences in the graph models produced by these algorithms, focussing on connectivity measures. To this aim, we compute the maximum number of vertex-disjoint valley-free paths between ASs as well as the size of a minimum cut separating a pair of ASs. Although these problems are solvable in polynomial time for ordinary graphs, they are NP-hard in our setting. We formulate the two problems as integer programs, and we propose a number of exact algorithms for solving them. For the problem of finding the maximum number of vertex-disjoint paths, we discuss two algorithms; the first one is a branch-and-price algorithm based on the IP formulation, and the second algorithm is a non LP based branch-and-bound algorithm. For the problem of finding minimum cuts we use a branch-and-cut algo rithm, based on the IP formulation of this problem. Using these algorithms, we obtain exact solutions for both problems in reasonable time. It turns out that there is a large gap in terms of the connectivity measures between the undirected and directed models. This finding supports our conclusion that economic relationships need to be taken into account when building a topology of the Internet.Research; Internet;

Transport in tunnelling recombination junctions: a combined computer simulation study

The implementation of trap-assisted tunneling of charge carriers into numerical simulators ASPIN and D-AMPS is briefly described. Important modeling details are highlighted and compared. In spite of the considerable differences in both approaches, the problems encountered and their solutions are surprisingly similar. Simulation results obtained for several tunneling recombination junctions made of amorphous silicon (a-Si), amorphous silicon carbide (a-SiC), or microcrystalline silicon (µc-Si) are analyzed. Identical conclusions can be drawn using either of the simulators. Realistic performances of a-Si/a-Si tandem solar cells can be reproduced with simulation programs by assuming that extended-state mobility increases exponentially with the electric field. The same field-enhanced mobilities are needed in single tunneling recombination junctions in order to achieve measured current levels. Temperature dependence of the current-voltage characteristics indicates that the activation energy of enhanced mobilities should be determined. Apparent discrepancies between simulation results and measurements are explained and eliminated making use of Gill’s law. For application in tandem and triple solar cell structures, tunneling recombination junctions made of (µc-Si) are the most promising of all examined structures.Fil: Vukadinovic, M.. University of Ljubljana; EsloveniaFil: Smole, F.. University of Ljubljana; EsloveniaFil: Topič, M.. University of Ljubljana; EsloveniaFil: Schropp, R. E. .. Utrecht University; Países BajosFil: Rubinelli, Francisco Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin

Investigating Robustness of Energy Management Maps for SMEs

Using the data from three small businesses, we are investigating robustness of the recently proposed Recurrence Quantitive Analysis (RQA) based method for energy management of small and medium enterprises. The method consists of two phases, the training phase where the map or maps of ‘usual’ behaviour is obtained, and the operational phase where the new data is tested against the existing map(s). We measure how the output changes when there is a small change in input, with respect to the sampling rate, missing data and noise. Our results over three qualitatively different datasets show that the method is relatively robust and can be used for different SMEs