Improved Methodology of Weather Window Prediction for Offshore Operations Based on Probabilities of Operation Failure

The offshore wind industry is building and planning new wind farms further offshore due to increasing demand on sustainable energy production and already occupied prime resource locations closer to shore. Costs of operation and maintenance, transport and installation of offshore wind turbines already contribute significantly to the cost of produced electricity and will continue to increase, due to moving further offshore, if the current techniques of predicting offshore wind farm accessibility are to stay the same. The majority of offshore operations are carried out by specialized ships that must be hired for the duration of the operation. Therefore, offshore wind farm accessibility and costs of offshore activities are primarily driven by the expected number of operational hours offshore and waiting times for weather windows, suitable for offshore operations. Having more reliable weather window estimates would result in better wind farm accessibility predictions and, as a consequence, potentially reduce the cost of offshore wind energy. This paper presents an updated methodology of weather window prediction that uses physical offshore vessel and equipment responses to establish the expected probabilities of operation failure, which, in turn, can be compared to maximum allowable probability of failure to obtain weather windows suitable for operation. Two case studies were performed to evaluate the feasibility of the improved methodology, and the results indicated that it produced consistent and improved results. In fact, the updated methodology predicts 57% and 47% more operational hours during the test period when compared to standard alpha-factor and the original methodologies

Towards a Risk-based Decision Support for Offshore Wind Turbine Installation and Operation & Maintenance

AbstractCosts of operation & maintenance, assembly, transport and installation of offshore wind turbines contribute significantly to the total cost of offshore wind farm. These operations are mostly carried out by specific ships that have to be hired for the operational phase and for duration of installation process, respectively. Duration, and therefore ship hiring costs is, among others, driven by waiting time for weather windows for weather-sensitive operations. Today, state of the art decision making criteria for weather-sensitive operations are restrictions to the significant wave height and the average wind velocity at reference height. However, actual limitations are physical, related to response of equipment used e.g. crane wire tension, rotor assembly motions while lifting, etc. Transition from weather condition limits to limits on physical equipment response in decision making would improve weather window predictions, potentially reducing cost of offshore wind energy. This paper presents a novel approach to weather window estimation using ensemble weather forecasts and statistical analysis of simulated installation equipment response

Teisėjų sprendimų priėmimas: intuityvus ir racionalus informacijos apdorojimas

[full article and abstract in Lithuanian; abstract in English] The contributions of judges’ intuitive and rational information processing making decisions on criminal (robbery) cases were evaluated. Results are interpreted in the context of cognitive psychology and discussed in relation to the contemporary trends and future perspectives in the field of legal decsion-making. Summary The aim of the current study is to investigate the contributions of judges’ intuitive and rational information processing making decisions on criminal (robbery) cases. 98 judges working in various courts of Lithuania‘s general jurisdiction participated in this study. We asked participants to solve two vignettes. One vignette was designed to be compatible with intuitive information processing (i. e., anchor provided at the end of the vignette suggested a correct decision), while another counter-intuitive (i. e., anchor suggested incorrect decision). 51 judges were instructed to solve vignettes intuiti- vely under a limit time (intuitive group), 47 judges – rationally with no time constraints (rational group). Results of the current study revealed that intuitive group decided on higher sentences (i.e. was closer to an anchor), compared to rational group. Additonally, we found that judges’ in rational group rational information processing contributed to 53.19%, and intuitive information processing – to 8,51% of all decision-making process. Moreover, judges’ in intuitive group rational information processing contributed to 35.29%, and intuitive information processing – to 15,68% of all decision-making process. Results are interpreted in the context of cognitive psychology.[straipsnis ir santrauka lietuvių kalba; santrauka anglų kalba] Straipsnyje analizuojamas santykinis teisėjų intuityvaus ir racionalaus informacijos apdorojimo pasireiškimas sprendžiant tariamus baudžiamųjų bylų scenarijus, susijusius su plėšimo nusikaltimais. Gauti rezultatai interpretuojami kognityvios psichologijos kontekste, taip pat aptariamas jų sąlytis su pastarųjų dešimtmečių mokslinės produkcijos tendencijomis ir tolesnėmis perspektyvomis

Reguliuojamos skrandžio apjuosimo juostos: lyginamųjų studijų apžvalga

Tomas Abalikšta, Gintautas Brimas, Kęstutis Strupas Vilniaus universiteto Medicinos fakultetas, M. K. Čiurlionio g. 21, LT-03101 Vilnius Vilniaus universiteto ligoninės Santariškių klinikų Pilvo chirurgijos centras, Santariškių g. 2, LT-08661 Vilnius El. paštas: [email protected] Darbo tikslas: Remiantis literatūros duomenimis palyginti skirtingas skrandžio apjuosimo reguliuojamas juostas, naudojamas chirurginiam nutukimo gydymui. Tyriamoji medžiaga ir metodai: Publikacijų paieška atlikta elektroninėse MEDLINE, Current Contents ir Cochrane Library duomenų bazėse. Apžvelgtos visos skrandį apjuosiančių reguliuojamų juostų lyginamųjų studijų publikacijos, paskelbtos iki 2010 m. sausio 1 d. Rezultatai: Atlikus literatūros šaltinių paiešką rasta 10 publikacijų, lyginančių skirtingas skrandį apjuosiančias reguliuojamas juostas. Išsamiai atlikta viena studija: perspektyvi, atsitiktinių imčių, jos tiriamųjų skaičius didelis ir stebėjimo laikotarpis ilgas, įvertinti visi gydymo rezultatai. Statistiškai reikšmingo skirtumo tarp SAGB ir LAP-BAND juostų šioje studijoje nerasta. Kitos lyginamosios juostų studijos turi trūkumų: keturios buvo ne atsitiktinių imčių (dvi iš jų retrospektyvios), trijose tiriamųjų imtis maža, visų stebėjimo laikas trumpas. Vienoje iš šių studijų nustatytas kūno masės kritimo skirtumas tarp grupių: LAP-BAND grupėje pradinė viršnorminė kūno masė sumažėjo 41,7 %, Heliogast – 28,3 %. Mechaninių juostų komplikacijų dažnis skyrėsi vienoje studijoje: LAP-BAND – 7 %, SAGB – 1 %. Skirtumas tarp „mažo skrandžio“ išsiplėtimo arba juostos nuslinkimo dažnio rastas trijose studijose (MiniMizer Extra – 0 % ir LAP-BAND – 10,8 %; SAGB – 2,4 % ir LAP-BAND – 27,6 %; SAGB – 2 % ir LAP-BAND – 23 %). Skirtumo tarp gretutinių ligų ir gyvenimo kokybės pokyčio, hospitalizacijos trukmės, juostos reguliavimų skaičiaus/dažnio, juostos penetracijos/migracijos į skrandį bei infekcinių komplikacijų dažnio nerasta. Išvados: Tik viena studija atlikta laikantis šiuolaikinių įrodymais pagrįstos medicinos keliamų reikalavimų, skirtumo tarp lygintų juostų nerasta. Reikalingos perspektyvios, atsitiktinių imčių ilgalaikės (>5 metų) lyginamosios studijos, vertinančios juostų konstrukcijos ar formos skirtumų įtaką gydymo efektyvumui ar komplikacijoms. Reikšminiai žodžiai: nutukimas, bariatrinė chirurgija, skrandžio apjuosimo reguliuojama juosta operacija. Adjustable gastric bands: review of comparative studies Tomas Abalikšta, Gintautas Brimas, Kęstutis Strupas Vilnius University Medical Faculty, M. K. Čiurlionio Str. 21, LT-03101 Vilnius, Lithuania Vilnius University Hospital Santariškių Klinikos Centre of Abdominal Surgery, Santariškių Str. 2, LT-08661 Vilnius, Lithuania El. paštas: [email protected] Objective: The objective of this review is to compare different adjustable gastric bands according to the data of comparative studies. Materials and Methods: A search of articles published in any language before January 2010 was carried out through the MEDLINE, Current Contents and Cochrane Library electronic databases. All articles about comparative studies of different adjustable gastric bands were eligible for review. All possible data were extracted from accepted studies and reviewed. Results: Ten comparative studies of different adjustable gastric bands were accepted. Only one comparative study of the bands was accomplished properly. It was a prospective randomised study type with a large number of patients and a long follow-up period with all possible results evaluated. No statistically significant difference between SAGB and LAP-BAND gastric bands was found in this study. The other band studies had shortcomings: four studies were non-randomised (two of them retrospective), a small number of patients in three studies, and a too short follow-up period in all studies. The difference in weight loss was stated in one of these studies: 41.7% of initial excess weight loss in the LAP-BAND group and 28.3% in the Heliogast group. Band leakage frequency was different in one study: LAP-BAND – 7%, SAGB – 1%. A difference between pouch dilatation or band slippage frequency was found in three studies (MiniMizer Extra – 0% and LAP-BAND – 10.8%; SAGB – 2.4% and LAP-BAND – 27.6%; SAGB – 2% and LAP-BAND – 23%). There was no difference between the resolution of comorbidities, improvement of the quality of life, hospital stay, band adjustment frequency, band migration or band infection rate. Conclusion: Only one accepted study was accomplished properly. There was no difference between compared adjustable gastric bands in this study. Prospective randomised long-term (more than 5 years) comparative studies are needed for a proper evaluation of band construction or shape influence on weight loss and complications. Keywords: obesity, bariatric surgery, adjustable gastric banding