SHIP OPERABILITY PREDICTED FROM LONG TERM DIRECTIONAL WAVE RECORDS

2021 ◽  
Vol 153 (A2) ◽  
Author(s):  
D A Wing ◽  
M C Johnson
Keyword(s):  
Ocean Waves ◽  
Computational Effort ◽  
Data Sets ◽  
Wave Data ◽  
Directional Wave ◽  
Performance Results ◽  
Buoy Data ◽  
Sea Area ◽  
Ship Performance

Ship operability assessments have traditionally been made using wind and wave data derived from wave atlases, however there are several drawbacks, including the fact that they are usually based on observation rather than measurement, and that spreading or directional effects are lost – such as the separation of sea and swell directions. An alternative approach is demonstrated here, instead of the data summarised in the wave atlas scatter diagram, long term hourly historical wave buoy data may be used. Detailed data sets, including directional wave spectra, are available for a number of specific locations. Direct use of many years’ hourly wave data involves significant computational effort, but results may be achieved within a reasonable time. The technique is demonstrated with the examples of four naval ships and two sites. Analysis considered two main themes, the differences in the ship performance calculated when (a) using wave buoy data rather than wave atlas data for the same sea area and (b) using the most complex available model of the ocean waves compared with the simplified wave descriptions in common use. For (a) the wave buoy data both looked rather different than the wave buoy data for the same nominal area, and produced rather different ship performance results. For (b) it was shown that there were also significant differences between the operability calculated for the four different ships at one of the sites. The implications for operability assessment in the ship procurement process are briefly discussed.

scholarly journals PRELIMINARY ASSESSMENT OF WAVE ENERGY IN SRI LANKA

2020 ◽  
pp. 21
Author(s):  
Kusalika Ariyarathne ◽  
Pavithra Jayarathne
Keyword(s):  
Sri Lanka ◽  
Wave Energy ◽  
Sri Lankan ◽  
Energy Potential ◽  
Wave Data ◽  
Density Maps ◽  
South West Monsoon ◽  
Near Shore ◽  
Directional Wave

Preliminary results of a numerical model developed to detail spatial and temporal assessment of theoretically available near shore wave energy, and potential wave energy extracting sites, along the Sri Lankan coast is presented in this paper. Wave energy is estimated applying Danish Hydraulic Institute's Mike 21 Spectral Wave (SW) module. The model is developed and applied covering an area along the coast line of entire country extending from 315000 to 640000 mE, and 602000 to 1164000 mN. Model was run with boundary inputs of wind and wave, based on long term measured, and long term hindcast directional wave data available at seven locations, which are well distributed around the country. Model calibration and validation are carried out based on long term measured directional wave data at Colombo, Sri Lanka. Based on the estimated wave energy density maps, and spatial and temporal energy variations, Hambantota, in South East coast is identified as the most feasible location for wave energy harnessing. Annual and seasonal availability of the wave energy, for Hambantota area, at 25 m depth, were looked into in detail. In the above area, mean annual energy potential was estimated as 10 kW/m at 25 m depth, whereas maximum annual potential energy was estimated as 36 kW/m. During South West monsoon, where high waves are present, the mean energy potential is estimated as 15 kW/m.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/dPa9istaB7A

scholarly journals EXTREME WAVE PREDICTION USING DIRECTIONAL DATA

1986 ◽  
Vol 1 (20) ◽  
pp. 11
Author(s):  
M.C. Deo ◽  
R. Burrows
Keyword(s):  
Directional Data ◽  
Irish Sea ◽  
Data Set ◽  
Wave Data ◽  
The North ◽  
Wave Heights ◽  
Directional Wave ◽  
The Irish Sea ◽  
Height Predictions

Potential inconsistencies in the predictions of long term wave heights can be experienced as a result of different methods of analysis possible when using directional wave data. This paper attempts to illustrate some of them. It involves analysis of two sets of directional wave data - one froa a coastal location in the Irish Sea and another from an offshore location in the North Sea. An attempt is made to eliminate the discrepancies between the long term return-value wave height predictions based upon the conditional height distributions associa ted with different direction sectors and those derived from the oonl-directional data set.

Extreme Wave Analysis in Campos Basin (Rio de Janeiro - Brazil) Associated With Extra-Tropical Cyclones and Anticyclones

2012 ◽  
Author(s):  
Ricardo M. Campos ◽  
Carlos Eduardo Parente ◽  
Ricardo de Camargo
Keyword(s):  
Rio De Janeiro ◽  
Ocean Waves ◽  
Extreme Wave ◽  
Considerable Uncertainty ◽  
Campos Basin ◽  
Distribution Tail ◽  
Directional Wave ◽  
Tropical Weather ◽  
Tail Of Distribution ◽  
Buoy Data

Campos Basin is a petroleum rich area located offshore of Rio de Janeiro, Brazil. The most energetic ocean waves that reach location are generated by extra-tropical weather systems. This article studies extreme waves generated by cyclones and anticyclones, using two approaches. The first is the statistical extreme analysis applying the Peaks Over Threshold technique. The second is an evaluation of metocean features of events selected by POT as the tail of distribution. The research used 42 months of directional wave buoy measurements from 1991 to 1995 and 20 years of WAVEWATCH III simulation from 1986 to 2005, forced by NCEP/NCAR reanalysis2 surface winds. From metocean evaluation, the authors conclude that the greatest swells hitting Campos Basin come from southwest direction, peak periods over 11 seconds, generated by cyclones, occurring mainly in winter and autumn. The extreme buoy data analysis of significant wave height resulted in return values for 50 and 100 year respectively 8.77 and 9.54 meters, but with considerable uncertainty due to the short duration of data collection. Despite the limitations of Wavewatch hindcast, the methodology was able to capture the characteristics of extreme events in terms of shape of the distribution tail.

Asian Americans and Pacific Islanders: Employment Issues in the United States

2011 ◽  
Vol 9 (1-2) ◽  
pp. 58-69
Author(s):  
Marlene Kim
Keyword(s):  
United States ◽  
Asian Americans ◽  
The United States ◽  
Current Data ◽  
Pacific Islanders ◽  
Native Hawaiians ◽  
Data Sets ◽  
High Poverty ◽  
Unemployment Rates

Asian Americans and Pacific Islanders (AAPIs) in the United States face problems of discrimination, the glass ceiling, and very high long-term unemployment rates. As a diverse population, although some Asian Americans are more successful than average, others, like those from Southeast Asia and Native Hawaiians and Pacific Islanders (NHPIs), work in low-paying jobs and suffer from high poverty rates, high unemployment rates, and low earnings. Collecting more detailed and additional data from employers, oversampling AAPIs in current data sets, making administrative data available to researchers, providing more resources for research on AAPIs, and enforcing nondiscrimination laws and affirmative action mandates would assist this population.

Epidemiological Evidence that Maternal Influenza Contributes to the Aetiology of Schizophrenia

1993 ◽  
Vol 163 (4) ◽  
pp. 522-534 ◽  
Author(s):  
W. Adams ◽  
R. E. Kendell ◽  
E. H. Hare ◽  
P. Munk-Jørgensen
Keyword(s):  
Data Sets ◽  
Time Lags ◽  
Epidemiological Evidence ◽  
Intrauterine Development ◽  
Increased Risk ◽  
Schizophrenic Patients ◽  
The Relationship ◽  
Monthly Incidence ◽  
Maternal Influenza

The epidemiological evidence that the offspring of women exposed to influenza in pregnancy are at increased risk of schizophrenia is conflicting. In an attempt to clarify the issue we explored the relationship between the monthly incidence of influenza (and measles) in the general population and the distribution of birth dates of three large series of schizophrenic patients - 16 960 Scottish patients born in 1932–60; 22 021 English patients born in 1921–60; and 18 723 Danish patients born in 1911–65. Exposure to the 1957 epidemic of A2 influenza in midpregnancy was associated with an increased incidence of schizophrenia, at least in females, in all three data sets. We also confirmed the previous report of a statistically significant long-term relationship between patients' birth dates and outbreaks of influenza in the English series, with time lags of - 2 and - 3 months (the sixth and seventh months of pregnancy). Despite several other negative studies by ourselves and others we conclude that these relationships are probably both genuine and causal; and that maternal influenza during the middle third of intrauterine development, or something closely associated with it, is implicated in the aetiology of some cases of schizophrenia.

scholarly journals A Novel LSTM Model with Interaction Dual Attention for Radar Echo Extrapolation

2021 ◽  
Vol 13 (2) ◽  
pp. 164
Author(s):  
Chuyao Luo ◽  
Xutao Li ◽  
Yongliang Wen ◽  
Yunming Ye ◽  
Xiaofeng Zhang
Keyword(s):  
Short Term Memory ◽  
Weather Forecast ◽  
Vital Role ◽  
Data Sets ◽  
Short Term ◽  
Learning Techniques ◽  
Radar Echo ◽  
Hidden States ◽  
Better Than

The task of precipitation nowcasting is significant in the operational weather forecast. The radar echo map extrapolation plays a vital role in this task. Recently, deep learning techniques such as Convolutional Recurrent Neural Network (ConvRNN) models have been designed to solve the task. These models, albeit performing much better than conventional optical flow based approaches, suffer from a common problem of underestimating the high echo value parts. The drawback is fatal to precipitation nowcasting, as the parts often lead to heavy rains that may cause natural disasters. In this paper, we propose a novel interaction dual attention long short-term memory (IDA-LSTM) model to address the drawback. In the method, an interaction framework is developed for the ConvRNN unit to fully exploit the short-term context information by constructing a serial of coupled convolutions on the input and hidden states. Moreover, a dual attention mechanism on channels and positions is developed to recall the forgotten information in the long term. Comprehensive experiments have been conducted on CIKM AnalytiCup 2017 data sets, and the results show the effectiveness of the IDA-LSTM in addressing the underestimation drawback. The extrapolation performance of IDA-LSTM is superior to that of the state-of-the-art methods.

scholarly journals LOWER BOUNDS OF CHARACTERISTIC SCALE OF TOPOLOGICAL MODIFICATION OF THE NEWTONIAN GRAVITATION

2012 ◽  
Vol 21 (05) ◽  
pp. 1250048
Author(s):  
L. IORIO
Keyword(s):  
Semimajor Axis ◽  
Data Sets ◽  
Orbital Elements ◽  
Dynamical Models ◽  
Spatial Direction ◽  
Newtonian Gravitation ◽  
Complementary Approach ◽  
Local Modification

We analytically work out the long-term orbital perturbations induced by the leading order of perturbing potential arising from the local modification of the Newton's inverse square law due to a topology ℝ2 × 𝕊1 with a compactified dimension of radius R recently proposed by Floratos and Leontaris. We neither restrict to any specific spatial direction [Formula: see text] for the asymmetry axis nor to particular orbital configurations of the test particle. Thus, our results are quite general. Nonvanishing long-term variations occur for all the usual osculating Keplerian orbital elements, apart from the semimajor axis which is left unaffected. By using recent improvements in the determination of the orbital motion of Saturn from Cassini data, we preliminarily inferred R ≳ 4-6 kau . As a complementary approach, the putative topological effects should be explicitly modeled and solved-for with a modified version of the ephemerides dynamical models with which the same data sets should be reprocessed.

Consistency of long-term marketable yield of carrot and onion cultivars in muck (organic) soil in relation to seasonal weather

2010 ◽  
Vol 90 (5) ◽  
pp. 755-765 ◽  
Author(s):  
M. T. Tesfaendrias ◽  
M. R. McDonald ◽  
J. Warland
Keyword(s):  
Allium Cepa ◽  
Daucus Carota ◽  
Organic Soil ◽  
Data Sets ◽  
Fresh Market ◽  
Marketable Yield ◽  
Daucus Carota L ◽  
Weather Patterns ◽  
The Mean

To identify carrot and onion cultivars that provide consistent marketable yields, we tracked the yields of five fresh market carrot [(Daucus carota L. subsp. sativus (Hoffm.) Arcang.] and six onion (Allium cepa L.) cultivars for at least 13 yr. Relationships between long-term weather variables and marketable yields were also investigated. The effects of cultivar, year and cultivar × year interactions on yield of carrots and onions were assessed. Cultivar and year had significant effects on carrot and onion yields, while the interaction was significant in only one of four data sets of carrot yield. Carrot cv. Cellobunch (95.4 t ha–1) and onion cv. Corona (74.1 t ha–1) had the highest mean marketable yields over the years studied. There was a slight positive correlation between mean yield of the assessed carrots and maximum temperatures in September (r = 0.44). Mean carrot yield was also somewhat negatively correlated with total rainfall in July (r = –0.43) and with number of days with rain in August (r = –0.43) and September (r = –0.44). Most onion cultivars showed stronger relationships between marketable yield and various weather patterns. Marketable yield of onions increased with an increase in the number of days with rainfall in June (r = 0.57). The mean marketable yield of the six onion cultivars decreased in relation to temperatures ≥30°C in June (r = –0.55) and August (r = –0.53). The mean yield of all the onions in the trials was negatively correlated (r = –0.78) with growing degree days (base 5°C, May to August). The results indicated that the data from long-term cultivar trials can be used to identify cultivars that yield well despite seasonal variations in weather. Key words: Daucus carota, Allium cepa, temperature, rainfall

scholarly journals Enhanced Care Assistant Training to Address the Workforce Crisis in Home Care: Changes Related to Job Satisfaction and Career Commitment

2007 ◽  
Vol 8 (2) ◽  
pp. 71-81 ◽  
Author(s):  
Constance L. Coogle ◽  
Iris A. Parham ◽  
Rita Jablonski ◽  
Jason A. Rachel
Keyword(s):  
Job Satisfaction ◽  
Home Care ◽  
Career Commitment ◽  
Management Training ◽  
Data Sets ◽  
Term Care ◽  
Training Models ◽  
Intrinsic Job Satisfaction

Changes in job satisfaction and career commitment were observed as a consequence of a geriatric case management training program focusing on skills development among personal care attendants in home care. A comparison of pretraining and posttraining scores uncovered a statistically significant increase in Intrinsic Job Satisfaction scores for participants 18–39 years of age, whereas levels declined among the group of middle aged participants and no change was observed among participants age 52 and older. On the other hand, a statistically significant decline in Extrinsic Job Satisfaction was documented over all participants, but this was found to be primarily due to declines among participants 40–51 years of age. When contacted 6–12 months after the training series had concluded, participants indicated that the training substantially increased the likelihood that they would stay in their current jobs and improved their job satisfaction to some extent. A comparison of pretraining and posttraining scores among participants providing follow-up data revealed a statistically significant improvement in levels of Career Resilience. These results are discussed as they relate to similar training models and national data sets, and recommendations are offered for targeting future educational programs designed to address the long-term care workforce shortage.

Sign in / Sign up

Export Citation Format

Share Document