Ising model in three dimensions with long-range power-law correlated site disorder: a Monte Carlo study

Folgende Arbeit beschäftigt sich mit dem Ising-Modell in drei Dimensionen auf einem {Gitter} mit einer langreichweitigen, potenzförmig korrelierten (\propto \dist^{-\aexp}) Unordnung mithilfe von Monte Carlo Simulationstechniken. Der Hauptteil der Arbeit ist die Bestimmung der {kritischen} Exponenten des Ising-Modells in Abhängigkeit von der Korrelationsstärke \aexp. Dies wird durch die Anwendung der Finite-Size-Scaling Analyse und der Temperatur-Scaling Analyse umgesetzt. Dabei wird insbesondere die Vorhersage von Weinrib und Halperin (ν = 2 / \aexp) überprüft. Weiterführend, werden die kritischen Temperaturen in Abhängigkeit vom Korrelationsexponenten \aexp und der Defektkonzentration ermittelt und die Hyperscaling-Relation studiert. Ergänzend werden vielfältige Aspekte, wie die Autokorrelation der Observablen, die Anwendung der Histogram-Reweighting-Methode und Messung der Korrelationsstärken \aexp auf Gittern erläutert.In this thesis the three-dimensional Ising model on a lattice with long-range power-law correlated ({\propto \dist^{-\aexp}}) site disorder is studied with the help of Monte Carlo simulation techniques. The key part of the work is the estimation of the critical exponents of the Ising model in dependence of the correlation strength \aexp. This is done by applying finite-size scaling analysis and the temperature scaling analysis. In particular, the conjecture by Weinrib and Halperin (ν = 2 / \aexp) is reviewed. Additionally, the critical temperatures in dependence of the correlation exponent \aexp and the concentration of defects are provided and the hyperscaling relation is checked. Supplementary, various aspects such as autocorrelation times of the observables, applicability of the histogram reweighting technique and the measured correlation exponents \aexp on the lattices are provided

Critical exponent ν\nu of the Ising model in three dimensions with long-range correlated site disorder analyzed with Monte Carlo techniques

We study the critical behavior of the Ising model in three dimensions on a lattice with site disorder by using Monte Carlo simulations. The disorder is either uncorrelated or long-range correlated with correlation function that decays according to a power-law $r^{-a}$. We derive the critical exponent of the correlation length $\nu$ and the confluent correction exponent $\omega$ in dependence of $a$ by combining different concentrations of defects $0.05 \leq p_d \leq 0.4$ into one global fit ansatz and applying finite-size scaling techniques. We simulate and study a wide range of different correlation exponents $1.5 \leq a \leq 3.5$ as well as the uncorrelated case $a = \infty$ and are able to provide a global picture not yet known from previous works. Additionally, we perform a dedicated analysis of our long-range correlated disorder ensembles and provide estimates for the critical temperatures of the system in dependence of the correlation exponent $a$ and the concentrations of defects $p_d$. We compare our results to known results from other works and to the conjecture of Weinrib and Halperin: $\nu = 2/a$ and discuss the occurring deviations

The economics of global LNG trade: the case of Atlantic and Pacific inter-basin arbitrage in 2010-2014

Abstract We examine the economic and strategic implications for gas supply security and diversity of Europe's reliance on global LNG markets. In particular, we carry out a detailed assessment of LNG trade between Atlantic and Pacific basins in 2011-2014, focusing on why there was not as much LNG arbitrage as might have been expected given the large price differential between these two regions in that period. By explicitly modelling a counterfactual scenario, in which LNG can be diverted to follow price differentials between Europe and Asia, we found that: (a) it is not the demand shock in Asia (driven by the Fukushima incident) per se but the high oil price in that period, as well as decoupling of European spot prices from oil-linked contract prices that created the huge natural gas price differentials between Asia and Europe; (b) amongst the largest LNG suppliers who could arbitrage between the Atlantic and Pacific regions, Qatar would have received the highest net benefit from diverting cargoes to Asia, however, these benefits are highly sensitive to the possibility of contract price renegotiations with Asian buyers (similar to what happened to large pipeline gas suppliers in Europe in the recent past); (c) furthermore, diverting contractual volumes from Europe to Asia would have required lengthy negotiations with European buyers who, as our modelling results suggest, did not necessarily have compelling commercial interests in sending contractual cargoes to Asia after taking into account that the surplus of LNG created in North-West Europe allowed these buyers to reduce high oil-linked contract prices with traditional pipeline suppliers. Thus, contrary to the currently prevailing view that European importers have largely 'overinvested' in LNG import capacity, these investments should be seen as a strategic bargaining option that European importers have developed to counterbalance the otherwise potentially larger pricing power of pipeline suppliers. Thus, investment in LNG import capacity reduces the need to invest in 'strategic and special relationship' with traditional suppliers to ensure against 'unfair' pricing practices

The economics of global LNG trade: the case of Atlantic and Pacific inter-basin arbitrage in 2010-2014

Abstract We examine the economic and strategic implications for gas supply security and diversity of Europe's reliance on global LNG markets. In particular, we carry out a detailed assessment of LNG trade between Atlantic and Pacific basins in 2011-2014, focusing on why there was not as much LNG arbitrage as might have been expected given the large price differential between these two regions in that period. By explicitly modelling a counterfactual scenario, in which LNG can be diverted to follow price differentials between Europe and Asia, we found that: (a) it is not the demand shock in Asia (driven by the Fukushima incident) per se but the high oil price in that period, as well as decoupling of European spot prices from oil-linked contract prices that created the huge natural gas price differentials between Asia and Europe; (b) amongst the largest LNG suppliers who could arbitrage between the Atlantic and Pacific regions, Qatar would have received the highest net benefit from diverting cargoes to Asia, however, these benefits are highly sensitive to the possibility of contract price renegotiations with Asian buyers (similar to what happened to large pipeline gas suppliers in Europe in the recent past); (c) furthermore, diverting contractual volumes from Europe to Asia would have required lengthy negotiations with European buyers who, as our modelling results suggest, did not necessarily have compelling commercial interests in sending contractual cargoes to Asia after taking into account that the surplus of LNG created in North-West Europe allowed these buyers to reduce high oil-linked contract prices with traditional pipeline suppliers. Thus, contrary to the currently prevailing view that European importers have largely 'overinvested' in LNG import capacity, these investments should be seen as a strategic bargaining option that European importers have developed to counterbalance the otherwise potentially larger pricing power of pipeline suppliers. Thus, investment in LNG import capacity reduces the need to invest in 'strategic and special relationship' with traditional suppliers to ensure against 'unfair' pricing practices

Brushless traction PM machines using commercial drive technology, part II: Comparative study of the motor configurations

In Part II a comparative analysis of the different brushless PM motor configurations, including exterior and interior rotor arrangements, salient and non-salient surface-mounted PM rotors, concentrated and distributed armature windings is presented. The comparative study is based on the developed design methodology given in the Part I of this paper. These motor configurations are investigated to be exploited for the particular automotive application - in-wheel hub traction motor of 80 kW, 1000 rpm base speed and constant power speed range of 4.5:1. It is shown that the interior surface-mounted non-salient PM motor with the concentrated winding is the most appropriate machine type for the considered application

Decadal changes in the Canary upwelling system as revealed by satellite observations: Their impact on productivity

Satellite-derived sea-surface temperature (SST) data were used to study the variability of the Canary Upwelling Ecosystem-CUE (12 to 43N) over the last two decades of the 20th century. The analysis reveals well known patterns of climatology and seasonal variability in this upwelling system. In contrast to quasi-regular decadal oscillations of SST anomalies observed in the open ocean, the coastal variability during the 1980s–1990s was better described as a decadal scale shift of the upwelling regime intensity. The analysis of the upwelling index and coastal zonal gradient of SST showed that this shift occurred earlier (∼1992) in the northern part of the CUE (off western Iberia) and some years later (∼1995) off the northwest African coast. The long-term variability of upwelling-favorable wind forcing during the examined period provides reasonable explanations for the observed shift of the upwelling intensity and its timing for the whole CUE. Finally, changes in the productivity of several small pelagic fish species observed for the same period suggest that there was a response of the ecosystem to these changes

Anterior Dynamic Versus Posterior Transpedicular Spinal Fusion for Lenke Type 5 Idiopathic Scoliosis: A Comparison of Long-term Results

Background. Despite the active implementation of dynamic correction in case of idiopathic scoliosis, there are no comparative studies of results of posterior and anterior dynamic correction in patients with completed and near-completed growth. Aim of the study to compare clinical and radiological results of anterior dynamic correction and conventional posterior transpedicular correction of Lenke type 5 scoliotic defonnities in patients with completed or near-completed growth. Methods. Eighty-six patients with Lenke type 5 scoliotic deformities were enrolled in the study. The first group (54 patients) underwent deformity correction via posterior approach using a rigid transpedicular system; the second group (32 patients) using dynamic correction system. Mean patients age was 22.612.8 and 27.310.9 years, respectively. We studied radiological data before surgery, immediately after surgery, and 2 or more years after surgery. Blood loss volume, duration of hospital stay, and duration of narcotic analgesics intake in the early postoperative period were analyzed. Functional results were assessed using SRS-22 questionnaire. Results. Preoperative Cobb angle in the first group was 65.5, and 27.5 at the long-term follow-up. Junctional kyphosis of T10-L2 before surgery was 21.0 and 13.2 at the long-term follow-up. Preoperative Cobb angle of the initial curve in the second group was 52.5 and 24.5 at the long-term follow-up. Junctional kyphosis of T10-L2 before surgery was 19.5, and 19.0 at the long-term follow-up. Nash and Moe apical vertebral rotation in the first group before surgery was 1.62 and 0.17 at the last follow-up; in the second group, it was 1.80 and 0.81, respectively. Mean number of fixed levels was 6.41.0 in the first group and 5.61.5 in the second group. Mobility of the thoracolumbar/lumbai curve was higher in the second group, 28.29.1, compared with 36.0 7.2 in the first group. Preoperatively, lumbar lordosis in the second group was 42.5, in the long-tenn period 43.5, and in the first group 43.4 and 44.3, respectively. Conclusion. Both posterior rigid and anterior dynamic correction in case of Lenke type 5 idiopathic scoliosis can provide satisfactory radiological results with initially similar thoracolumbar deformities in patients with completed or nearcompleted growth. However, dynamic approach can reduce blood loss, duration of hospital stay, duration of narcotic analgesics intake after surgery, and improve quality of life in the long-term period.Актуальность. Несмотря на активное внедрение динамической коррекции при идиопатическом сколиозе, отсутствуют сравнительные исследования результатов дорсальной и вентральной динамической коррекции у пациентов с завершенным и завершающимся ростом. Цель исследования сравнить клинические и рентгенологические результаты вентральной динамической коррекции и традиционной дорсальной транспедикулярной коррекции сколиотических деформаций типа Lenke 5 у пациентов с завершенным или завершающимся ростом. Материал и методы. В исследование было включено 86 пациентов со сколиотическими деформациями типа Lenke 5. В первой группе (54 пациента) выполняли коррекцию деформации из дорсального доступа с использованием ригидной транспедикулярной системы, во второй группе (32 пациента) с применением системы для динамической коррекции. Средний возраст пациентов составил 22,612,8 и 27,310,9 лет соответственно. Изучали рентгенологические данные до операции, сразу после операции и через 2 и более года после операции. Анализировали объем кровопотери, сроки пребывания в стационаре, длительность приема наркотических анальгетиков в раннем послеоперационном периоде. Функциональные результаты оценивали с использованием опросника SRS-22. Результаты. В первой группе угол Кобба до операции составил 65,5, при отдаленном наблюдении 27,5. Переходный кифоз Th10-L2 до операции составил 21,0, при отдаленном наблюдении 13,2. Предоперационный угол Кобба основной дуги во второй группе 52,5, а в отдаленные сроки 24,5. Переходный кифоз Th10-L2 до операции 19,5, в отдаленные сроки 19,0. Ротация апикального позвонка по Nash Мое в первой группе до операции составила 1,62, при последнем осмотре 0,17, во второй группе 1,80 и 0,81 соответственно. Среднее количество фиксированных уровней составило в первой группе 6,41,0, во второй 5,61,5. Мобильность грудо-поясничной/поясничной дуги была выше во второй группе 28,29,1 по сравнению с первой группой с 36,07,2. До операции поясничный лордоз у пациентов второй группы составил 42,5, в отдаленные сроки 43,5, у пациентов первой группы 43,4 и 44,3 соответственно. Заключение. Как задняя ригидная, так и вентральная динамическая коррекция при идиопатическом сколиозе Lenke 5 могут обеспечить удовлетворительный рентгенологический результат при изначально схожей величине грудопоясничных деформаций у пациентов с завершенным или завершающимся ростом. Однако динамический подход позволяет сократить объем кровопотери, срок пребывания в стационаре, длительность приема наркотических анальгетиков после операции, а также улучшить качество жизни в отдаленном периоде

The time-frequency method of signal analysis in internal combustion engine diagnostics

The paper presents the results of the study of applicability of time-frequency correlation functions to solving the problems of internal combustion engine fault diagnostics. The proposed methods are theoretically justified and experimentally tested. In particular, the method's applicability is illustrated by the example of specially generated signals that simulate the vibration of an engine both during the normal operation and in the case of a malfunction in the system supplying fuel to the cylinders. This method was confirmed during an experiment with an automobile internal combustion engine. The study offers the main findings of the simulation and the experiment and highlights certain characteristic features of time-frequency autocorrelation functions that allow one to identify malfunctions in an engine's cylinder. The possibility in principle of using time-frequency correlation functions in function testing of the internal combustion engine is demonstrated. The paper's conclusion proposes further research directions including the application of the method to diagnosing automobile gearboxes

The time-frequency method of signal analysis in internal combustion engine diagnostics

The paper presents the results of the study of applicability of time-frequency correlation functions to solving the problems of internal combustion engine fault diagnostics. The proposed methods are theoretically justified and experimentally tested. In particular, the method's applicability is illustrated by the example of specially generated signals that simulate the vibration of an engine both during the normal operation and in the case of a malfunction in the system supplying fuel to the cylinders. This method was confirmed during an experiment with an automobile internal combustion engine. The study offers the main findings of the simulation and the experiment and highlights certain characteristic features of time-frequency autocorrelation functions that allow one to identify malfunctions in an engine's cylinder. The possibility in principle of using time-frequency correlation functions in function testing of the internal combustion engine is demonstrated. The paper's conclusion proposes further research directions including the application of the method to diagnosing automobile gearboxes