scholarly journals The Time Window for Vessels Without Ice Strengthening On the Northern Sea Route

2016 ◽  
Vol 23 (1) ◽  
pp. 103-120 ◽  
Author(s):  
Tadeusz Pastusiak
Keyword(s):  
Time Window ◽  
Time Frame ◽  
Time Range ◽  
Dynamic Changes ◽  
Northern Sea Route ◽  
Decision Supporting ◽  
Ice Conditions ◽  
Arctic Ice ◽  
Estimation Of Time ◽  
Daily Changes

Abstract The work discusses possibility to make transit voyages of vessels without ice strengthening on the Northern Sea Route (NSR). Exist many uncertainties for it. They are related to hydro-meteorological conditions, mostly to ice cover on the Russian Arctic. Ice conditions are under dynamic changes in time and space. Is hard to precisely predict ice conditions now, in the time range of one month and so on. Statistical historical data of daily changes same like yearly changes show a considerable scatter of the data. The author analyzed number of ice-free days of particular seas of the NSR in the latest eight years. The results of this work may be used for estimation of time frame (time window) for transport of cargo on the NSR by means of vessels without ice strengthening. The statistical presentation of ice-free days data was used in the work to develop decision supporting method related to planning vessel voyage including ice-free time frame on particular seas of the Northern Sea Route.

scholarly journals Análisis comparativo de una metaheurística en base a algoritmo genético vs un método de ramificación y corte para un caso de entrega y recolección con restricciones de ventana de horario

2017 ◽  
Vol 1 (2) ◽  
Author(s):  
Fabian López
Keyword(s):  
Time Window ◽  
Time Frame ◽  
Branch And Cut ◽  
Pickup And Delivery ◽  
Np Hard ◽  
Practical Application ◽  
High Quality ◽  
Method Of Solution ◽  
Time Window Constraints ◽  
Computational Resources

Palabras claves: Algoritmos genéticos, logística de ruteo, metaheuristicas, secuenciaciónResumen. En la solución de problemas combinatorios, es importante evaluar el costo-beneficio entre la obtención de soluciones de alta calidad en detrimento de los recursos computacionales requeridos. El problema planteado es para el ruteo de un vehículo con entrega y recolección de producto y con restricciones de ventana de horario. En la práctica, dicho problema requiere ser atendido con instancias de gran escala (nodos ≥100). Existe un fuerte porcentaje de ventanas de horario activas (≥90%) y con factores de amplitud ≥75%. El problema es NP-hard y por tal motivo la aplicación de un método de solución exacta para resolverlo en la práctica, está limitado por el tiempo requerido para la actividad de ruteo. Se propone un algoritmo genético especializado, el cual ofrece soluciones de buena calidad (% de optimalidad aceptables) y en tiempos de ejecución computacional que hacen útil su aplicación en la práctica de la logística. Para comprobar la eficacia de la propuesta algorítmica se desarrolla un diseño experimental el cual hará uso de las soluciones óptimas obtenidas mediante un algoritmo de ramificación y corte sin límite de tiempo. Los resultados son favorables.Key words: Genetic algorithms, routing logistics, metaheuristics, schedulingAbstract. In an attempt to sovle the combinatorics problems, it is important to evaluate the costbenefit ratio between obtaining solutions of high quality and the loss of the computational resources required. The problem presented is for the routing of a vehicle with pickup and delivery of products with time window constraints. This problem requires instances of great scale (nodes≥100). A strong active time window percentage exists (≥90%) with factors of amplitude ≥75%. The problem is NP-hard and hence, the application of an exact method of solution, is limited by the time frame required for routing activity. A specialized genetic algorithm is proposed, which offers solutions of high precision and in computational times that makes its practical application useful. An experimental design is developed with good results that makes use of optimum solutions obtained by means of branch and cut algorithm without time limit.

scholarly journals Time window for postoperative reactive enhancement after resection of brain tumors: less than 72 hours

2014 ◽  
Vol 37 (6) ◽  
pp. E3 ◽  
Author(s):  
Stephanie Lescher ◽  
Sonja Schniewindt ◽  
Alina Jurcoane ◽  
Christian Senft ◽  
Elke Hattingen
Keyword(s):  
Brain Tumor ◽  
Contrast Enhancement ◽  
Tumor Recurrence ◽  
Time Window ◽  
Time Frame ◽  
Tumor Surgery ◽  
Mr Images ◽  
Brain Tumor Surgery ◽  
Postoperative Mri ◽  
Field Strengths

Object Early postoperative MRI within 72 hours after brain tumor surgery is commonly used to assess residual contrast-enhancing tumor. The 72-hour window is commonly accepted because previous 1.5-T MRI studies have not found confounding postoperative reactive contrast enhancement in this time frame. The sensitivity to detect contrast enhancement increases with the field strengths. Therefore, the authors aimed to assess whether the 72-hour window is also appropriate for the MRI scanner with a field strength of 3 T. Methods The authors retrospectively analyzed findings on early postsurgical MR images acquired in 46 patients treated for high-grade gliomas. They performed 3-T MRI within 7 days before surgery and within 72 hours thereafter. The appearance of enhancement was categorized as postoperative reactive enhancement or tumoral enhancement by comparison with the pattern and location of presurgical enhancing tumor. Results Postoperative reactive enhancement was present in 15 patients (32.6%). This enhancement, not seen on presurgical MRI, had a marginal or leptomeningeal/dural pattern. In 13 patients (28.3%) postsurgical enhancement was found within the first 72 postoperative hours, with the earliest seen 22:57 hours after surgery. Subsequent MR scans in patients with postoperative reactive enhancement did not reveal tumor recurrence in these regions. Conclusions Postoperative reactive enhancement earlier than 72 hours after brain tumor surgery can be expected in about one-third of the cases in which a 3-T scanner is used. This might be due to the higher enhancement-to-brain contrast at higher field strengths. Therefore, the time window of 72 hours does not prevent reactive enhancement, which, however, can be recognized as such comparing it with presurgical enhancing tumor.

scholarly journals Implication of methodological uncertainties for mid-Holocene sea surface temperature reconstructions

2014 ◽  
Vol 10 (6) ◽  
pp. 2237-2252 ◽  
Author(s):  
I. Hessler ◽  
S. P. Harrison ◽  
M. Kucera ◽  
C. Waelbroeck ◽  
M.-T. Chen ◽  
...  
Keyword(s):  
Climate Model ◽  
Time Window ◽  
Planktonic Foraminifera ◽  
Regional Scale ◽  
Time Frame ◽  
Sea Surface ◽  
Model Simulations ◽  
Climate Model Simulations ◽  
Analytical Approaches ◽  
Baseline Climate

Abstract. We present and examine a multi-sensor global compilation of mid-Holocene (MH) sea surface temperatures (SST), based on Mg/Ca and alkenone palaeothermometry and reconstructions obtained using planktonic foraminifera and organic-walled dinoflagellate cyst census counts. We assess the uncertainties originating from using different methodologies and evaluate the potential of MH SST reconstructions as a benchmark for climate-model simulations. The comparison between different analytical approaches (time frame, baseline climate) shows the choice of time window for the MH has a negligible effect on the reconstructed SST pattern, but the choice of baseline climate affects both the magnitude and spatial pattern of the reconstructed SSTs. Comparison of the SST reconstructions made using different sensors shows significant discrepancies at a regional scale, with uncertainties often exceeding the reconstructed SST anomaly. Apparent patterns in SST may largely be a reflection of the use of different sensors in different regions. Overall, the uncertainties associated with the SST reconstructions are generally larger than the MH anomalies. Thus, the SST data currently available cannot serve as a target for benchmarking model simulations. Further evaluations of potential subsurface and/or seasonal artifacts that may contribute to obscure the MH SST reconstructions are urgently needed to provide reliable benchmarks for model evaluations.

AN OVERVIEW OF A FIELD GUIDE FOR ARCTIC OIL SPILL BEHAVIOR1

1985 ◽  
Vol 1985 (1) ◽  
pp. 399-403
Author(s):  
Robert Schulze ◽  
Ivan Lissauer
Keyword(s):  
Physical Properties ◽  
Oil Spill ◽  
Cold Water ◽  
Field Guide ◽  
Ice Conditions ◽  
Arctic Ice

ABSTRACT A Field Guide for Oil Spill Behavior was developed to provide the On-Scene Coordinator with the spill behavior information needed to ensure timely and adequate containment and removal. The guide describes arctic ice conditions, the physical properties of oil as it weathers, oil spill behavior in cold water and ice conditions, and spill retention potential for the Alaskan shoreline. Six spill scenarios show the user how to apply spill behavior information to solve actual problems.

Dynamic Changes in the Mental Rotation Network Revealed by Pattern Recognition Analysis of fMRI Data

2009 ◽  
Vol 21 (5) ◽  
pp. 890-904 ◽  
Author(s):  
Janaina Mourao-Miranda ◽  
Christine Ecker ◽  
Joao R. Sato ◽  
Michael Brammer
Keyword(s):  
Pattern Recognition ◽  
Functional Connectivity ◽  
Mental Rotation ◽  
Temporal Dynamics ◽  
Parietal Lobe ◽  
Time Window ◽  
Support Vector ◽  
Dynamic Changes ◽  
Angular Disparity ◽  
Spatio Temporal

We investigated the temporal dynamics and changes in connectivity in the mental rotation network through the application of spatio-temporal support vector machines (SVMs). The spatio-temporal SVM [Mourao-Miranda, J., Friston, K. J., et al. (2007). Dynamic discrimination analysis: A spatial-temporal SVM. Neuroimage, 36, 88–99] is a pattern recognition approach that is suitable for investigating dynamic changes in the brain network during a complex mental task. It does not require a model describing each component of the task and the precise shape of the BOLD impulse response. By defining a time window including a cognitive event, one can use spatio-temporal fMRI observations from two cognitive states to train the SVM. During the training, the SVM finds the discriminating pattern between the two states and produces a discriminating weight vector encompassing both voxels and time (i.e., spatio-temporal maps). We showed that by applying spatio-temporal SVM to an event-related mental rotation experiment, it is possible to discriminate between different degrees of angular disparity (0° vs. 20°, 0° vs. 60°, and 0° vs. 100°), and the discrimination accuracy is correlated with the difference in angular disparity between the conditions. For the comparison with highest accuracy (0° vs. 100°), we evaluated how the most discriminating areas (visual regions, parietal regions, supplementary, and premotor areas) change their behavior over time. The frontal premotor regions became highly discriminating earlier than the superior parietal cortex. There seems to be a parcellation of the parietal regions with an earlier discrimination of the inferior parietal lobe in the mental rotation in relation to the superior parietal. The SVM also identified a network of regions that had a decrease in BOLD responses during the 100° condition in relation to the 0° condition (posterior cingulate, frontal, and superior temporal gyrus). This network was also highly discriminating between the two conditions. In addition, we investigated changes in functional connectivity between the most discriminating areas identified by the spatio-temporal SVM. We observed an increase in functional connectivity between almost all areas activated during the 100° condition (bilateral inferior and superior parietal lobe, bilateral premotor area, and SMA) but not between the areas that showed a decrease in BOLD response during the 100° condition.

scholarly journals Sexual selection gradients change over time in a simultaneous hermaphrodite

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Jeroen NA Hoffer ◽  
Janine Mariën ◽  
Jacintha Ellers ◽  
Joris M Koene
Keyword(s):  
Sexual Selection ◽  
Reproductive Success ◽  
Mating Success ◽  
Time Window ◽  
Time Frame ◽  
Male Reproductive Success ◽  
Simultaneous Hermaphrodite ◽  
Selection Gradients ◽  
Short Time Window ◽  
Over Time

Sexual selection is generally predicted to act more strongly on males than on females. The Darwin-Bateman paradigm predicts that this should also hold for hermaphrodites. However, measuring this strength of selection is less straightforward when both sexual functions are performed throughout the organism’s lifetime. Besides, quantifications of sexual selection are usually done during a short time window, while many animals store sperm and are long-lived. To explore whether the chosen time frame affects estimated measures of sexual selection, we recorded mating success and reproductive success over time, using a simultaneous hermaphrodite. Our results show that male sexual selection gradients are consistently positive. However, an individual’s female mating success seems to negatively affect its own male reproductive success, an effect that only becomes visible several weeks into the experiment, highlighting that the time frame is crucial for the quantification and interpretation of sexual selection measures, an insight that applies to any iteroparous mating system.

scholarly journals Economics and politics of “old confrontation” in the New Arctic

2021 ◽  
Vol 24 (4-2021) ◽  
pp. 7-20
Author(s):  
Asja A. Shchegol'kova ◽  
Keyword(s):  
National Security ◽  
Spatial Development ◽  
Water Area ◽  
The Arctic ◽  
Climatic Fluctuations ◽  
Northern Sea Route ◽  
Ice Conditions ◽  
Strategic Space ◽  
Arctic Policy ◽  
Economics And Politics

The modern Arctic is becoming the strategic space and area of competition of many powers, the arena of political confrontations between Arctic and non-Arctic states. Arctic research has moved from the sphere of science to the sphere of geopolitics and geoeconomics and is of strategic importance in the system of national security. Climatic fluctuations in the Arctic have increased the availability of hydrocarbon, biological and other resources, and improved ice conditions in the water area of the Northern Sea Route. The study analyzes the Arctic policy of Western European and North American countries in the conditions of the “New Arctic”. An overview of strategic documents on ensuring the spatial development.

Climate Change Impact on Canadian Northern Shipping Regulations

2007 ◽  
Vol 44 (04) ◽  
pp. 245-253
Author(s):  
Ivana Kubat ◽  
Robert Gorman ◽  
Anne Collins ◽  
Garry W. Timco
Keyword(s):  
Climate Change ◽  
Climate Change Impact ◽  
The Arctic ◽  
Northwest Passage ◽  
Impact Of Climate Change ◽  
Ice Conditions ◽  
Change Impact ◽  
Ice Regime ◽  
Arctic Ice ◽  
The Impact

The objective of this study was to find what effect climate change would have on the Zone-Date System (ZDS). The paper presents an analysis of ice conditions in the Northwest Passage (NWP) shipping lanes and the access routes to the Port of Churchill in the Hudson Strait. The analysis examines the existing and potential changes to ice regimes in the NWP shipping lanes due to the impact of climate change. The length of the shipping season in the NWP is analyzed for each zone by both the ZDS and the Arctic Ice Regime Shipping System, and both systems are then compared. This paper discusses the results of the analysis.

Northern Sea Route: Modern State and Challenges

2014 ◽  
Author(s):  
Nataliya Marchenko
Keyword(s):  
Oil And Gas ◽  
Chukchi Sea ◽  
Lessons Learned ◽  
Economic Feasibility ◽  
Asia Pacific ◽  
Russian Arctic ◽  
The North ◽  
Technical Requirements ◽  
Northern Sea Route ◽  
Ice Conditions

It is well-known that navigating the waterway from the primary trade hubs in northern Europe to the Asia-Pacific ports and contrariwise along the Russian Arctic Coast (Northern Sea Route - NSR) is much shorter and faster, than southern ways via Suez or around Africa. The NSR can significantly save costs (through saving time and fuel) and avoids the risk of attack by pirates. In addition, an increase in oil and gas activity in the North, forecasts of global warming and an ice-free Arctic have stimulated interest in Arctic navigation. However, Arctic transportation poses significant challenges because of the heavy ice conditions that exist during both the winter and summer. The profitability of using the NSR is called into question if possible high tariffs are included in the cost estimates. For many years, the NSR was principally used for internal Russian transport and since the end of the 1980s up until 2010, it was in stagnation with total amount of cargo transported annually stood at less than two million tons. Important political decisions in the 90s and increased economic feasibility intensified traffic and freight turnover. In 2013, the NSR Administration (NSRA) was established, new rules for navigation were approved and tariff policies were modified. In 2013, the NSRA issued 635 permits to sail in NSR waters, and 71 transit voyages have since been completed. The total amount of transit cargo was 1.36 million tons. More than 40% of the total number of permits were issued to vessels without ice class [1] according to the Russian Maritime Register of Shipping [2]. There are strong technical requirements for vessels attempting to sail the NSR; regardless, several accidents occurred in 2012–2013. Two vessels were dented by ice in the Chukchi Sea in 2012. A tanker was holed in September 2013 and created a real danger of an ecological disaster from fuel leakage for several days. Despite the expectation of an ice-free Arctic, the ice conditions in 2013 were rather difficult, and the Vilkitsky Strait (a key strait in the NSR between the Kara and Laptev seas) was closed by ice for almost the entire navigation period. In this paper, we review the current situation in the Russian Arctic, including political and administrative actions, recent accidents and the associated conditions and lessons learned.

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