Letteratura scientifica selezionata sul tema "Watering points"
Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili
Consulta la lista di attuali articoli, libri, tesi, atti di convegni e altre fonti scientifiche attinenti al tema "Watering points".
Accanto a ogni fonte nell'elenco di riferimenti c'è un pulsante "Aggiungi alla bibliografia". Premilo e genereremo automaticamente la citazione bibliografica dell'opera scelta nello stile citazionale di cui hai bisogno: APA, MLA, Harvard, Chicago, Vancouver ecc.
Puoi anche scaricare il testo completo della pubblicazione scientifica nel formato .pdf e leggere online l'abstract (il sommario) dell'opera se è presente nei metadati.
Articoli di riviste sul tema "Watering points"
1
Montague-Drake, R., e DB Croft. "Do kangaroos exhibit water-focused grazing patterns in arid New South Wales? A case study in Sturt National Park." Australian Mammalogy 26, n. 1 (2004): 87. http://dx.doi.org/10.1071/am04087.
Testo completoAbstract (sommario):
The density of kangaroos (Macropus spp.) within 5 km of current and former artificial watering points in Sturt National Park (NSW) was studied over a two-year period using the line transect method. Kangaroo densities were not significantly related to water proximity and did not significantly differ between open and closed watering points. Infrared sensors detected and counted kangaroo movements to and from artificial watering points and these were positively correlated with temperature. However, line transect counts did not reveal a shift in kangaroo distributions to water-proximate areas in warmer seasons. The results suggest that kangaroos travel to drink and then return to relatively stable home ranges that take advantage of sites offering the best grazing and resting opportunities. Vegetation surveys, using a wheel point device, revealed that the biomass of Atriplex spp. decreased significantly with increased proximity to artificial watering points, but the biomass of Poaceae spp. and numerous forbs did not. Vegetative diversity was unrelated to water proximity. Low vegetation biomass near artificial watering points in Sturt National Park may be more correctly attributed to the effects from past sheep-grazing pressure, than to any current grazing pressure. The implications of artificial watering point closure on conservation values and nature-based tourism are discussed.
2
Andrew, M. H. "Grazing impact in relation to livestock watering points". Trends in Ecology & Evolution 3, n. 12 (dicembre 1988): 336–39. http://dx.doi.org/10.1016/0169-5347(88)90090-0.
Testo completo
3
Thrash, I. "Impact of large herbivores at artificial watering points compared to that at natural watering points in Kruger National Park, South Africa". Journal of Arid Environments 38, n. 2 (febbraio 1998): 315–24. http://dx.doi.org/10.1006/jare.1997.0331.
Testo completo
4
Norbury, GL. "An electrified watering trough that selectively excludes kangaroos." Rangeland Journal 14, n. 1 (1992): 3. http://dx.doi.org/10.1071/rj9920003.
Testo completoAbstract (sommario):
It is generally agreed that the provision of artificial watering points has allowed populations of large kangaroos to increase in the arid and semi-arid rangelands. This study examines the effectiveness of a selective watering device, known as a 'Finlayson Trough', that is designed to exclude kangaroos but allow sheep to drink. The device is a low-lying electrified wire that surrounds a trough and is overstepped by sheep but contacted by a kangaroo's feet or tail. Of the 292 observed attempts at drinking by red kangaroos (Macropus rufis), 99% were unsuccessful. Most shocks were received through the feet. Of the 309 observed attempts at drinking by sheep, minor shocks to the legs were received in 17% of cases. These resulted in only short-term disruptions to drinking. Finlayson Troughs could be used humanely to facilitate commercial kangaroo harvesting by exploiting local concentrations of kangaroos around watering points; to control the distribution of kangaroos in sensitive regenerating areas; or, by gradual implementation, to allow kangaroos to adjust their behaviour to accommodate fewer artificial watering points.
5
Finch, N. A., P. J. Murray, M. T. Dunn e J. Billingsley. "Using machine vision classification to control access of animals to water". Australian Journal of Experimental Agriculture 46, n. 7 (2006): 837. http://dx.doi.org/10.1071/ea05325.
Testo completoAbstract (sommario):
Invasive vertebrate pests together with overabundant native species cause significant economic and environmental damage in the Australian rangelands. Access to artificial watering points, created for the pastoral industry, has been a major factor in the spread and survival of these pests. Existing methods of controlling watering points are mechanical and cannot discriminate between target species. This paper describes an intelligent system of controlling watering points based on machine vision technology. Initial test results clearly demonstrate proof of concept for machine vision in this application. These initial experiments were carried out as part of a 3-year project using machine vision software to manage all large vertebrates in the Australian rangelands. Concurrent work is testing the use of automated gates and innovative laneway and enclosure design. The system will have application in any habitat throughout the world where a resource is limited and can be enclosed for the management of livestock or wildlife.
6
Wang, Hong Mei, Xu Ming Long e Ai Ling Luo. "Intelligent Monitoring Water System by PLC (Power Line Carrier) and Wireless Communication". Advanced Materials Research 846-847 (novembre 2013): 283–87. http://dx.doi.org/10.4028/www.scientific.net/amr.846-847.283.
Testo completoAbstract (sommario):
To saves water resources and low carbon environmental, we have designed a smart monitoring watering system based on power carrier and wireless communications, the system schema is divided into three layer, background server control the concentrated controller through wireless core network; each concentrated controller controls watering system through power carrier network; watering systems as the terminal access points of The Internet of Things , directly control the location regional's temperature, humidity and the soil situation, thereby achieved unmanned unattended, automatically watering. System integrates technology as wireless communications, power line carrier, single-chip microcomputer , application in LCD and so on, through hardware and software design, realizes data storage, the node information query, node failures and cable guard alarm function. Experimental results show that the overall system has low power consumption, high reliability, strong anti-jamming ability, so that it can better meet site's needs.
7
Huang, Shih-Chang, e Ye-Ze Lin. "A Low-Cost Constant-Moisture Automatic Irrigation System Using Dynamic Irrigation Interval Adjustment". Applied Sciences 10, n. 18 (12 settembre 2020): 6352. http://dx.doi.org/10.3390/app10186352.
Testo completoAbstract (sommario):
This paper developed a Soil Moisture Forecasting (SMF) model and a Constant-moisture Automatic Irrigation System (CAIS). The SMF model used the soil moisture data at different depths in an experimental plot inside a greenhouse to infer the soil moisture level after a specific interval. CAIS integrated the SMF data with dynamic watering interval adaption to maintain soil moisture at a constant level. Most intelligent irrigation products incur high installation costs that farmers cannot afford. CAIS used a low-cost component to achieve the same functionality that is found in intelligent irrigation products. Most low-cost irrigation systems water the plants from a single point that may lead to variable soil moisture if the terrain or the soil density is uneven. CAIS divided the experimental plot into multiple virtual planting areas (VPAs) and dynamically adapted the watering interval of each VPA to balance the soil moisture of the whole experimental plot. Results showed that the forecasting error of the SMF model was less than 12 moisture levels over a scale of 1024 levels. Furthermore, CAIS maintained the soil moisture of the whole experimental plot at a constant level within ±5 error points with multiple watering points.
8
Croft, DB. "Inter- and Intra specific Conflict between Arid-zone Kangaroos at Watering Points". Wildlife Research 12, n. 3 (1985): 337. http://dx.doi.org/10.1071/wr9850337.
Testo completoAbstract (sommario):
Red kangaroos Macropus rufus and euros M. robustus were observed drinking at a stock trough in northwestern New South Wales. The populations of both species were divided into five age-sex classes. Drinking and agonistic behaviour was similar across classes and species. Inter- and intraspecific conflict between these classes for a drinking position were analysed. Within species, there is a size-related hierarchy for gaining and maintaining a drinking space, favouring the larger class. Interspecifically, euros, the smaller species, dominate equivalent age classes of red kangaroos. Retaliation in aggressive encounters is more likely between adjacent rank neighbours than those more distant in the hierarchy. Drinking individuals tend to win more encounters than individuals attempting to gain a drinking place. The longer a kangaroo has been drinking the less likely it is to act aggressively to an intruder. When drinking, spacing between kangaroos is essentially random. Both species displace another individual at a similar mean distance of 0.6-0.8 m, but spacing between adult euros is wider than between adult red kangaroos. Spacing is modified by the relative positions of neighbours on either side of the trough. The results are discussed in terms of social and other factors that may have led to the euro's dominance of the red kangaroo at water.
9
Malan, Julie-Ann C., Nicole Flint, Emma L. Jackson, Andrew D. Irving e Dave L. Swain. "Offstream watering points for cattle: Protecting riparian ecosystems and improving water quality?" Agriculture, Ecosystems & Environment 256 (marzo 2018): 144–52. http://dx.doi.org/10.1016/j.agee.2018.01.013.
Testo completo
10
Adler, Peter B., e Sonia A. Hall. "The development of forage production and utilization gradients around livestock watering points". Landscape Ecology 20, n. 3 (aprile 2005): 319–33. http://dx.doi.org/10.1007/s10980-005-0467-1.
Testo completoTesi sul tema "Watering points"
1
Montague-Drake, Rebecca School of Biological Earth & Environmental Sciences UNSW. "Strategic management of artificial watering points for biodiversity conservation". Awarded by:University of New South Wales. School of Biological, Earth and Environmental Sciences, 2004. http://handle.unsw.edu.au/1959.4/30122.
Testo completoAbstract (sommario):
Since pastoralism began in Australia???s rangelands, the number of artificial watering points (AWPs) has increased dramatically, such that today, few areas of rangeland are further than 10 km from water. This increased availability of water has caused many ecological impacts. Unfortunately, such impacts are poorly understood in the context of an Australian conservation reserve, thus hindering strategic management. This study examined the spatial distribution of vertebrate (kangaroos, small mammals, lizards and avifauna) and vegetative variables around open AWPs as well as AWPs that have been closed since pastoralism (sheep-grazing) ceased nearly thirty years ago in Sturt National Park, arid New South Wales. The study also examined vertebrate use of AWPs, with a particular emphasis on kangaroos and avifauna. The study revealed that most variables showed few differences in spatial distribution with distance from open and closed AWPs, thus suggesting that the observed piospheric impacts were primarily attributable to historical sheep-grazing. Indeed, piospheric patterns were weak suggesting some recovery over the last thirty years. That kangaroos did not exhibit water-focused grazing is no surprise, since despite their regular use of AWPs, particularly during hot, dry times, the current spatial arrangement of AWPs facilitates regular travel to, and from, such resources allowing kangaroos, like much other fauna, to distribute themselves in relation to food and shelter preferences rather than in relation to water supply. In contrast, the majority of avifaunal groups (excluding ground-dwelling species) were clustered around open AWPs, often irrespective of season, because of food and water requirements. Such spatial concentrations of avifauna are thought to cause a range of interspecific effects. Experimental AWP closure and GIS modelling showed that whilst closure of AWPs will increase the average distance to water, which will have key benefits, the majority of areas in Sturt National Park would still be accessible to most water-dependent species even if all unused AWPs were closed. Strategic retention of AWPs to replace water sources lost since European settlement, aid threatened and migratory species??? conservation and enhance nature-based tourism opportunities is thus recommended and an example of a strategic management and monitoring plan outlined.
2
Fukuda, Yuki. "The effects of closing watering points on populations of large macropods and landscape rehabilitation in a semi-arid national park /". [St. Lucia, Qld.], 2006. http://adt.library.uq.edu.au/public/adt-QU20060511.125915/index.html.
Testo completo
3
Harrington, Rhidian. "The effects of artificial watering points on the distribution and abundance of avifauna in an arid and semi-arid mallee environment". Connect to this title online, 2002. http://repository.unimelb.edu.au/10187/2874.
Testo completoAbstract (sommario):
The role of artificial watering points in the avifaunal dynamics of the semi-arid mallee woodlands of southeast Australia was examined. Species richness and abundance were monitored throughout the year at different distances from water to determine how birds were distributed around water points and how this changed in relation to environmental factors such as climate. Vegetation attributes were also measured to determine which factors explained patterns in the avifauna with distance from water, and also to allow a description of the vegetation in relation to the water points. Water points were monitored throughout the year to determine which species were utilising them, under which environmental circumstances and for what purposes. Knowledge of the water utilisation behaviour of individual bird species allowed some explanation of their distribution patterns, as well as an ability to predict the likely effects of water point closure on those bird species. The closure of two water points during the study allowed an assessment of the immediate effects of water point closure on avifauna (For complete abstract open document)
4
Herzog, Margaret June. "Optimization of Point-of-Use Water Treatment Device for Disaster Relief". DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/474.
Testo completoAbstract (sommario):
Point-of-use (POU) drinking water treatment is a common method of providing drinking water in disaster relief situations when critical water infrastructure is damaged. In these cases, POU treatment devices can be used to treat local water until relief organizations set up more permanent water provision methods. One such POU technology is PŪR® Purifier of Water, a combined coagulation/flocculation and disinfection chemical treatment sachet produced by Procter & Gamble. PŪR® has been shown to treat contaminated water to meet water quality standards and guidelines set by the U.S. EPA for water purifiers and by the World Health Organization and The Sphere Project for emergency relief. However, the standard two-bucket method of use for PŪR® has two primary drawbacks: (1) the need for appurtenances that may not be readily available in disaster relief situations and (2) lack of a means to protect treated water from re-contamination post-treatment. An alternative to the two-bucket method is a waterbag system under development at the California Polytechnic State University, San Luis Obispo. The waterbag is a ten-liter plastic bladder with integrated filter that incorporates an all-in-one approach to drinking water treatment during emergencies. In previous studies, the first version of the waterbag consistently met World Health Organization and The Sphere Project emergency drinking water guidelines, but did not meet the pathogen reduction requirements of the U.S. EPA Guide Standard and Protocol for Testing Microbiological Water Purifiers.
A second (Mark II) version, with internal mixing baffles and a microfilter, was developed to overcome the inability of the first design to meet the U.S. EPA guidelines. The main purposes of the research presented herein were to (1) optimize the method of use and baffle configuration for the improved Mark II version of the waterbag, (2) determine ability of the waterbag to treat test waters with challenging initial water quality conditions, and (3) test the ability of the Mark II design and optimized method to meet the U.S. EPA Guide Standard and Protocol for Testing Microbiological Water Purifiers.
For the first and second objectives, the main metric of treatment performance was the extent of flocculation, which was characterized by the turbidity of waterbag supernatant after 30 minutes of settling. The waterbag procedure was varied in several ways. The variables tested were mixing duration, mixing motion type, and the effect of a mixing delay. Several waterbag baffle designs were tested to determine the physical configuration of the waterbag which resulted in best turbulence during mixing. In addition, experiments were performed to test the ability of the Mark II waterbag to treat waters with various initial qualities, such as high organic carbon content and elevated E. coli concentrations. The results of these experiments helped to prepare for a final test in meeting the pathogen removal requirements of the U.S. EPA Guide Standard and Protocol for Testing Microbiological Water Purifiers.
The procedure determined to be optimal for the Mark II waterbag treatment included five minutes of mixing using rapid 180° twisting motions at a moderate frequency of seventy 180°-twists per minute. The optimal baffle design was a 12.7 cm-wide internal mixing baffle with two cut circular holes for the promotion of turbulence during mixing. The desired post-treatment chlorine residual was achieved for different durations depending on initial organic carbon concentration. Optimal PŪR® dose to provide pathogen removals required by the U.S. EPA in the presence of Challenge Water conditions was two sachets per 10 L of water to be treated. The optimization of these design and operational procedures led to the ability of the Mark II waterbag to meet the pathogen, turbidity, pH, and non-microbiological constituent removals required by the U.S. EPA, The Sphere Project, and World Health Organization for emergency relief.
5
Brits, Jacques. "Ecological impact of large herbivores on woody vegetation at selected watering points in the Kruger National Park". Diss., 1999. http://hdl.handle.net/2263/30185.
Testo completo
6
Chiou, Min-Huei, e 邱敏惠. "Using Ant Colony Optimization to Solve Periodic Arc Routing Problem with Refill Points – A Case of Street Trees Watering". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/76378624768491996004.
Testo completoAbstract (sommario):
碩士國立高雄第一科技大學
運籌管理研究所
99
This research represents a solving process for Periodic Arc Routing Problem with Refill Points (PARPRP) using Ant Colony Optimization (ACO). Each link in the network requires diverse service times in a week, thus, the routes for a vehicle are different day by day. The vehicle capacity will be resumed in a refill point. This research transforms the original arc routing problem into a vehicle routing problem by means of treating the links in the initial network as hyper nodes. The Ant Colony Optimization algorithm is adopted in this research to solve the PARPRP and the solving process is also applied on some instances which retrieved from the literature. The output results of the instances are listed. In addition to the instances, a real case of street tree watering in KaoHsiung city is analyzed as well. The results indicate that the proposed solving process is stable and is capable of providing excellent solution in reasonable CPU time.
Libri sul tema "Watering points"
1
1945-, Francis Diane DeMali, a cura di. Cedar Point: The queen of American watering places. Canton, Ohio: Daring Books, 1988.
Cerca il testo completo
2
Francis, David W. Cedar Point: The queen of American watering places. Fairview Park, Ohio: Amusement Park Books, 1995.
Cerca il testo completoCapitoli di libri sul tema "Watering points"
1
"Satellite image processing and geo-statistical methods for assessing land degradation around watering points in the Ust-Urt Plateau, Kazakhstan". In Recent Advances in Remote Sensing and Geoinformation Processing for Land Degradation Assessment, 333–42. CRC Press, 2009. http://dx.doi.org/10.1201/9780203875445-28.
Testo completo
2
Svoray, T., U. Gilad e A. Karnieli. "Satellite image processing and geo-statistical methods for assessing land degradation around watering points in the Ust-Urt Plateau, Kazakhstan". In International Society for Photogrammetry and Remote Sensing (ISPRS) Book Series, 313–22. CRC Press, 2009. http://dx.doi.org/10.1201/9780203875445.ch20.
Testo completo
3
O'Connor, Kevin C. "Watering the Nations: Riga and the Northern Crusades". In The House of Hemp and Butter, 39–68. Cornell University Press, 2019. http://dx.doi.org/10.7591/cornell/9781501747687.003.0003.
Testo completoAbstract (sommario):
This chapter explores the notion of Riga as a “city of God” to which thousands of monk-knights and other warriors arrived to do battle with the pagans in Livonia, which the crusaders called the “Land of Mary.” Here, the chapter considers the city's role in the Baltic crusade as both a regional trading center and as a gathering point for military expeditions against pagans and Rus'. Riga was virtually surrounded by native tribes, and both pagans and newly baptized converts. And within the city was a military order dedicated to holy war. Riga was also, in every respect, a colonial city, dominated by strangers to the region who arrived in shiploads to make a comfortable living, conquer territory, and spread the faith.
4
Worthy, Ben. "The 1999 draft Bill: the retreat becomes a rout". In The Politics of Freedom of Information. Manchester University Press, 2017. http://dx.doi.org/10.7228/manchester/9780719097676.003.0005.
Testo completoAbstract (sommario):
This chapter follows the process from January 1998 to the much delayed publication of the draft bill in 1999. The FOI bill ‘swapped’ policy team and, at this point, shifted the source of policy drive. With no internal champions the push came from a combination of the legislature, the media and the government’s own waning sense of duty to its manifesto. The chapter focuses on the growing internal pressure from within the government to change the FOI commitment. Irvine’s combative approach led to short term success but a lack of consensus for moving forward. The proposed policy was threatening to key politicians and officials but also vulnerable due to the flaws within it. As Irvine’s radical plans stalled, senior figures, including the Prime Minister had growing doubts about the policy. Flaws in the White Paper were used to revise and weaken the policy while the fading power of the radical FOI group was reduced by Lord Irvine’s own personal loss of influence. The key moment came in 1998 when FOI was transferred from supporter Irvine to sceptic Jack Straw and the Cabinet Office team broken up. This led to a much more detailed but much weaker draft FOI bill, which inserted a veto power for government and reduced the power of the independent reviewer. The original proposals were modified within the Cabinet committee. Yet the bill survived in part due to the insertion of a ‘five year’ implementation gap and the government’s lukewarm commitment to its reform agenda. However, the bill was not a wholesale watering down, as it added Parliament to the Act’s coverage.
5
Ehrenfeld, David. "I Reinvent Agriculture". In Swimming Lessons. Oxford University Press, 2002. http://dx.doi.org/10.1093/oso/9780195148527.003.0032.
Testo completoAbstract (sommario):
Many of us who work with pencil, pen, or computer like to vary the intellectual routine by doing something “real.” Some build cabinets and canoes, some sing in choral groups, others join first aid squads. I take care of our garden. Gardening is an especially good activity for eggheads because it combines physical labor with the opportunity to be creative. Unlike the ideas in the books I write, however, my creations in the gar-den are quickly put to the test. My experience last summer is a case in point. I like to eat what I grow, so I have little patience with flowers and other ornamentals. I tolerate the ones that were planted around the house when we first arrived: yew, hemlock, cherry laurel, forsythia, flame azalea—the usual things provided by botanically challenged, cost-conscious builders. If these woody perennials get sick I do what I can for them, given my lack of knowledge and low level of interest. Some times I fertilize, sometimes I continue to refrain from fertilizing, depending on my intuition in the particular case. The same goes for watering. Our flame azalea is down to one tiny branch with eleven leaves on it, about the same as last year. I don’t know whether I am keeping it alive against all odds, or preventing it from making the full recovery that it would be capable of if cared for by somebody else. I view my role in the treatment of our ornamental plantings like that of the remote HMO clerk who makes the critical decisions in a complex medical case; any unfortunate consequences of my ignorance are not of great concern. Fruits and vegetables are another matter. I am not much more knowledgeable about them than about azaleas, but I try a lot harder. Because this is a story about vegetables, I will skip the fruits, except to note that we pick our own sour cherries, figs, peaches, plums, grapes, apricots, and apples—in sharply decreasing order of abundance (squirrels got all of my apples this year).
Atti di convegni sul tema "Watering points"
1
Dahliani, Lili, e Rinaldi Saputra. "The Effect of Distance Measurement Point of Watering Sample on The Amount of Watering Water Palm Oil Nursery". In 2018 International Conference on Applied Science and Technology (iCAST). IEEE, 2018. http://dx.doi.org/10.1109/icast1.2018.8751607.
Testo completo
2
Martin, David E. "PCLINES, A Parametric Lines Development Program for the Home Computer". In SNAME 18th Chesapeake Sailing Yacht Symposium. SNAME, 2007. http://dx.doi.org/10.5957/csys-2007-011.
Testo completoAbstract (sommario):
An Excel© spreadsheet lines development program has been written for a home computer and is available to conference attendees. The program utilizes B-Spline parametric formulations for planar curve definition of the traditional hull lines: body, waterlines and buttocks. The user establishes the basic hull outline, in BSpline curves, by inputting bow and stern overhangs, freeboard at selected points, the draft of the canoe body at selected points, the beam on deck at selected points, and the maximum beam at the waterline. By judicious selections the user will see the resulting hull outline in profile and plan views, and can easily adjust these inputs to gain the desired hull outline. The user works with actual points on the hull rather than B-Spline vertices. The hull lines are then developed by the Excel program which establishes the hull form defined by the above outlines and satisfying inputs of the conventional hull form parameters: Center of Buoyancy, (Lcb) Center of Floatation, (Lcf) Prismatic Coefficient, (Cp), Maximum Section Coefficient, (Cm) and the Water-plane Coefficient, (Cwp). The lines development is accomplished in two steps. First, the user employs the Excel Solver to establish a waterline, and Sectional Area curve that satisfy the above parameters. The program accomplishes this by varying the draft at stations two and eight, which adjusts the shape of the center-plane curve without changing the draft, Tc. The solver ensures a “fair” waterline by minimizing the “bending” criterion of the waterline: that is, by minimizing the sum of the squares of d2y/du2 and d2x/du2. Here, y and x are defined by B-Spline formulations in the parameter “u”. The vertices of the B-Spline functions are varied by the Excel Solver to find the minimum bending criterion. Second, with the Section Area and waterline beam established for each station, the program establishes the shape of each station body curve which satisfies the section area, draft, freeboard and beams on deck and waterline. Fairness is again established by minimizing the “bending” criterion. Since there are no section areas for stations 10 and the transom, a scheme for constructing a transomgeometrically similar to station 9.5 is provided. Station 10 is established by fairing to the transom. The program can establish a round bottom hull in about a minute and a half after the input parameters are entered. It is essential however that the hull form parameters be selected judiciously. Clearly Lcb and Lcf must be compatible, and the hull outline must be reasonable in order to gain a fair hull. In this regard the user is provided with automatic input of six different hull shapes that provide good starting points for a design effort. Thus, in a matter of minutes the user can examine an alternate hull shape while keeping selected hull form parameters constant.
3
Xenitidis, Kleanthis, Vassilios Mardiris e Vassilios Chatzis. "A novel methodology for sailing boat waterline plane definition using 3D point cloud". In 2017 Panhellenic Conference on Electronics and Telecommunications (PACET). IEEE, 2017. http://dx.doi.org/10.1109/pacet.2017.8259977.
Testo completo
4
Liu, Yujie, e Jeffrey M. Falzarano. "Improvement on the Accuracy of Mean Drift Force Calculation". In ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/omae2017-62321.
Testo completoAbstract (sommario):
Accurate computation of the drift forces and moments is required to study the higher order steady excitations on the floater in waves. One of the components of the drift forces and moments is regarding the relative wave elevation. To obtain this term, we need an accurate estimation of the wave elevation. If the field point is exactly on the waterline, we will encounter some difficulty to get the potential value. This paper will provide a more accurate method to calculate the wave elevation around the body and discuss the mathematical justifications. The accuracy will be validated by the comparison against the commercial software. When using more panels in the commercial software, the results will converge to those from our in-house program. We observe a large discrepancy in the relatively higher frequency range. The sharp spikes in the original method are not observed in the improved method. Therefore it is necessary to adopt the proposed method in order to provide more reasonable predictions of the mean drift forces.
5
Hong, D. C., S. Y. Hong e H. G. Sung. "Numerical Study of the Ship Motion in Waves Using the Three-Dimensional Time-Domain Forward-Speed Free-Surface Green Function and a Second-Order Boundary Element Method". In ASME 2008 27th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/omae2008-57146.
Testo completoAbstract (sommario):
The radiation and diffraction potentials of a ship advancing in waves are calculated in the time-domain using the three-dimensional time-domain forward-speed free-surface Green function and the Green integral equation on the basis of the Neumann-Kelvin linear wave hypothesis. The Green function approximated by Newman for large time is used together with the Green function by Lamb for small time. The time-domain diffraction problem is solved for the time derivative of the potential by using the time derivative of the impulsive incident wave potential represented by using the complementary complex error function. The integral equation for the potential is discretized according to a second-order boundary element method where the collocation points are located inside the panel. It makes it possible to take account of the line integral along the waterline in a rigorous manner. The six-degree-of-freedom motion and memory functions as well as the diffraction impulse response functions of a hemisphere and the Wigley seakeeping model are presented for various Froude numbers. Comparisons of the wave damping and exciting force and moment coefficients for zero forward speed, calculated by using the Fourier transforms of the time-domain results and the frequency-domain coefficients calculated by using the improved Green integral equation which is free of the irregular frequencies, have been shown to be satisfactory. The wave damping coefficients for non-zero forward speed, calculated by using Fourier transforming of the present time-domain results have also been compared to the experimental results and agreement between them has been shown to be good. A simulation of coupled heave-pitch motion of the Wigley seakeeping model advancing in regular head waves of unit amplitude has been carried out.
6
Liu, Xiang, Yingying Chen, Hai Gu e Jer-Fang Wu. "A Random Solution to Ice-Induced Vibrations of Conical Structures". In ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/omae2015-41696.
Testo completoAbstract (sommario):
Offshore installations designed to withstand extreme ice actions, such as the multi-leg structures in Cook Inlet, the gravity based Molikpaq during its mobilization in the Beaufort Sea, lighthouses and channel markers in the Baltic Sea, jackets and mooring poles in Bohai Bay and multi-leg structures offshore Sakhalin, have experienced ice-induced vibrations (IIVs). Full-scale data from Bohai Bay also demonstrate that a conical waterline geometry of the structure does reduce the magnitude of the ice forces, but it still experiences IIVs that can be treated as a stochastic process. ISO 19906 recommends that the dynamic ice actions and the corresponding IIVs shall be considered in the design as the fatigue limit state (FLS). ISO 19906 provides the guidance for the time-domain random dynamic ice action on conical structures. The dynamic structural response to such ice action can take the form of a random vibration. As an alternative to the time-domain approach, random vibration analysis can also be done in the frequency domain by the spectral approach. In addition to the time-domain random dynamic ice action on conical structures provided in ISO 19906, a type of ice-force spectrum on conical structures has been developed. In this paper, a simplified single-degree-of-freedom system (SDOF system) and the ice-force spectrum are used to derive an analytical random solution to assess the IIVs of conical structures. As ISO 19906 points out that particular attention shall be given to dynamic actions on narrow structures and flexible structures, the developed random solution can be useful for designers to make a fast estimate of IIVs (i.e., displacement, velocity and acceleration) and to efficiently screen out the key design parameters of a conical ice-resistant structure.
7
Grant, Howard, Walter Stubner, Walter Alwang, Charles Henry, John Baird e Paul Spens. "Schooner Brilliant Sail Coefficients and Speed Polars". In SNAME 15th Chesapeake Sailing Yacht Symposium. SNAME, 2001. http://dx.doi.org/10.5957/csys-2001-011.
Testo completoAbstract (sommario):
The sail coefficients for a schooner rig, as a function of wind angle and heel angle, are presented, based on an experimental program, for historic vessel research, at Mystic Seaport, using the 61'6" schooner Brilliant. The coefficients were determined by full-scale sailing tests and 9- scale model tow-tank tests. Sail coefficients CR and Cttare defined as the drive force and horizontal side force , due to the sails, rigging, and hull above the waterline, per unit of sail area, per unit of wind pressure. These coefficients can be used to study performance of historic schoonerrigged vessels, predict performance of new designs, and compare performance of schooners and sloops. Sail coefficients for sloops have long been available. A velocity prediction program for the schooner was also developed. The predicted and actual ship speeds agree, with standard deviation of0.028 in the ratio. Upwind sail coefficients for the schooner are found to be lower than for historic sloops, and display the expected droop with heel. The schooner velocity made good upwind is largest with the sail plan of four lowers plus fisherman staysail. The schooner and sloop both point higher as wind increases. The sloop outpoints the schooner at all wind speeds, by about 10°. On a beam reach or broad reach, schooner speed is largest with the sail plan of big jib, golliwobbler, and mainsail. This sail plan also produces the largest downwind velocity made good. The polars suggest that the schooner has the advantage over the sloop on a beam reach.
8
Inoue, Yoshiyiki, e Md Kamruzzaman. "A Numerical Calculation of Hydrodynamic Forces on a Seagoing Ship by 3-D Source Technique With Forward Speed". In ASME 2004 23rd International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2004. http://dx.doi.org/10.1115/omae2004-51565.
Testo completoAbstract (sommario):
In this paper, the hydrodynamic forces of a surface ship advancing in waves at constant forward speed are numerically calculated by using the 3-D source distribution techniques. The paper also deals with the numerical calculations of free surface flow around an advancing ship in calm water as well as in waves. The body boundary condition is linearised about the undisturbed position of the body and the free surface condition is linearised about the mean water surface. The potential is represented by a distribution of sources over the surface of the ship and its waterline. The problem is solved by the method of singularities distributed over the hull surface. Hess & Smith method is used to obtain the density of these singularities. The numerical solution of the surface ship case is approximately obtained by considering the hull as a position of plane polygonal elements, bearing a constant singularity distribution. The velocity potential of any particular point in the free surface around the moving hull is determined by using the 3-D Green function with forward speed which satisfies the boundary conditions for a pulsating source in the fluid. Contours of wave patterns around moving surface ships are calculated from the velocity potential. The numerical accuracy of the computer code is firstly checked by calculating the velocity potential of a translating, pulsating unit source with arbitrary frequency and forward speed. Free surface wave patterns generated by a Wigley hull advancing with steady forward speed are calculated by using this code. Some corresponding hydrodynamic coefficients of heave and pitch modes for the Wigley hull has been calculated. Exciting forces and motion amplitudes are also investigated. The numerical result of this code is validated by comparing the calculated results with the experimental ones and those calculated by other methods. From the comparison, the results predicted by the present calculations are found in fairly good agreement with the experiment. Finally, the effects of motion amplitude on the free surface elevation are analyzed. These will be helpful for the accurate estimation of sea keeping problems for a ship advancing in waves.