Letteratura scientifica selezionata sul tema "Hull (Computer program)"
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Articoli di riviste sul tema "Hull (Computer program)"
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Jang, Chang Doo, Ho Kyung Kim e Ha Cheol Song. "Optimum Structural Design of High-Speed Surface Effect Ships Built of Composite Materials". Marine Technology and SNAME News 40, n. 01 (1 gennaio 2003): 42–48. http://dx.doi.org/10.5957/mt1.2003.40.1.42.
Testo completoAbstract (sommario):
A surface effect ship is known to be comparable to a high-speed ship. For the structural design of surface effect ships, advanced design methods are needed which can reflect the various loading conditions different from those of conventional ships. Also, minimum weight design is essential because hull weight significantly affects the lift, thrust powering and high-speed performance. This paper presents the procedure of optimum structural design and a computer program to minimize the hull weight of surface effect ships built of composite materials. By using the developed computer program, the optimum structural designs for three types of surface effect ships—built of sandwich plate only, stiffened single skin plate only, and both plates—are carried out and the efficiency of each type is investigated in terms of weight. The computer program, developed herein, successfully reduced the hull weight of surface effect ships by 15–30% compared with the original design. Numerical results of optimum structural designs are presented and discussed.
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Anshary, Muhammad Adi Khairul, Eka Wahyu Hidayat e Tiara Amalia. "Prototype Program Hand Gesture Recognize Using the Convex Hull Method and Convexity Defect on Android". Jurnal Online Informatika 5, n. 2 (3 dicembre 2020): 205. http://dx.doi.org/10.15575/join.v5i2.594.
Testo completoAbstract (sommario):
One of the research topics of Human-Computer Interaction is the development of input devices and how users interact with computers. So far, the application of hand gestures is more often applied to desktop computers. Meanwhile, current technological developments have given rise to various forms of computers, one of which is a computer in the form of a smartphone whose users are increasing every year. Therefore, hand gestures need to be applied to smartphones to facilitate interaction between the user and the device. This study implements hand gestures on smartphones using the Android operating system. The algorithm used is convex hull and convexity defect for recognition of the network on the hand which is used as system input. Meanwhile, to ensure this technology runs well, testing was carried out with 3 scenarios involving variable lighting, background color, and indoor or outdoor conditions. The results of this study indicate that Hand gesture recognition using convex hull and convexity defect algorithms has been successfully implemented on smartphones with the Android operating system. Indoor or outdoor testing environment greatly affects the accuracy of hand gesture recognition. For outdoor use, a green background color with a light intensity of 1725 lux produces 76.7% accuracy, while for indoors, a red background color with a light intensity of 300 lux provides the greatest accuracy of 83.3%.
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Clay, John S. "Salvage of Stranded Tankers with the Aid of Computers". Marine Technology and SNAME News 22, n. 04 (1 ottobre 1985): 382–93. http://dx.doi.org/10.5957/mt1.1985.22.4.382.
Testo completoAbstract (sommario):
The threat of large-scale pollution by tankers offers an incentive to increase our present knowledge in vessel groundings. The lack of research and technical writing as to the effects of waves on a vessel aground is emphasized. A procedure is developed to evaluate the likelihood of exceeding longitudinal strength of stranded tankers in waves. A software modification to Ship Hull characteristics Program (SHCP), a highly used naval architecture program, is described. The modification allows modeling of ground reaction for hull strength calculations of stranded vessels. An analytical technique for predicting hull failure based on the probability of wave height exceedance is presented. Computer runs using the hull form of a coastal tanker are evaluated. Pertinent environmental parameters acting on grounded vessels are defined. New salvage data collection procedures and equipment are proposed. The need to apply current microcomputer technology to salvage is addressed, and proposed hardware and software systems are included. Based on the work presented, sound initial salvage decisions, which increase hull survivability and decrease the chances of pollution, can be made. It is proposed that new technologies can augment a salvor's feel for the dynamics involved in salvage engineering.
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Dejhalla, Roko, Zoran Mrša e Senka Vukovic´. "A Genetic Algorithm Approach to the Problem of Minimum Ship Wave Resistance". Marine Technology and SNAME News 39, n. 03 (1 luglio 2002): 187–95. http://dx.doi.org/10.5957/mt1.2002.39.3.187.
Testo completoAbstract (sommario):
A genetic algorithm-based optimization method is proposed for an optimization of a ship hull from a hydrodynamic point of view. In the optimization procedure, the wave resistance has been selected as an objective function. The genetic algorithm is coupled with a computer program for solving the three-dimensional potential flow around a ship hull. The potential flow solver is based upon the well-known Dawson method. The optimization procedure has been applied to the Series 60 CB = 0.60 hull taken as a basis hull. The computational examples show the optimization ability of the proposed method.
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Xhaferaj, Blenard. "INVESTIGATION ON SOME CONVENTIONAL HULLS FORMS OF THE PREDICTIVE ACCURACY OF A PARAMETRIC SOFTWARE FOR PRELIMINARY PREDICTIONS OF RESISTANCE AND POWER". Brodogradnja 73, n. 1 (1 gennaio 2022): 1–22. http://dx.doi.org/10.21278/brod73101.
Testo completoAbstract (sommario):
Preliminary prediction of resistance and power is a fundamental aspect of the ship design process since they directly influence the developments of the design process, fuel consumption and costs, and environmental impact from the early design stage. Parametric predictions of resistance and power, based mainly on statistical regression models that are also ideal for computer programming, are often performed during initial design stages, providing rapid predictions and optimisations for minimum resistance. The paper aims to present the results of the comparative analysis on some conventional hulls of the predictive accuracy of a computer program developed by the author for parametric predictions of resistance and power of ships. The program (entitled Ship Power V 1.0) is developed in the Visual Basic 6.0 environment based on two well-known regression models Holtrop and Van Oortmerssen. The program can perform detailed predictions of resistance and power, resistance coefficients, propeller thrust, hull efficiency, wake, and trust fractions, with no restriction on the number of velocities. In this study, only the analysis of the accuracy of resistance and power prediction is considered. Results of the comparative analysis of the computational procedures of Ship Power V 1.0 versus experimental data, and against results of another well-known commercial software, performed on three models of the Ridgely-Nevitt trawler series and KCS hull have shown a good level of accuracy and reliability as other well-known commercial software.
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Aydin, Muhsin, e Aydin Salci. "Geometrical Characteristics of Fishing Boats Series of ITU". Marine Technology and SNAME News 44, n. 02 (1 aprile 2007): 125–37. http://dx.doi.org/10.5957/mt1.2007.44.2.125.
Testo completoAbstract (sommario):
In the present paper, first 13 hull forms of fishing boats with different block coefficients were generated. Later, 26 hull forms of fishing boats with two different ratios of length to beam were generated by utilizing previous hull forms of fishing boats mentioned. In total, 39 fishing boats were generated. This series is called "Fishing Boats Series of ITU" (Istanbul Technical University). In this Series, the forms of the body stations and beams of the boats are the same for equal block coefficient and different lengths. The ratio of the beam of any station at any waterline to the beam of boat, Bz/B varies with respect to block coefficient, CB. These variations have been represented with the third-degree polynomials. Thus, a hull form of the fishing boat in the desired length and block coefficient can be obtained by using these polynomials. For this purpose, a computer program called "Turetme" was developed. Finally, by using this program, three hull forms of fishing boats were obtained and presented here.
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Zborowski, Andrew, e Simon R. Sainsbury. "Small Vessel Hull Form Optimization for Heave and Pitch Performance". Marine Technology and SNAME News 25, n. 04 (1 ottobre 1988): 293–303. http://dx.doi.org/10.5957/mt1.1988.25.4.293.
Testo completoAbstract (sommario):
The Ship Motion Program (SMP) originally written for a mainframe computer system has been adapted for use on the IBM PC microcomputer family and subsequently applied to study ship seakeeping performance. The converted program, referred to as the Ship Seakeeping Characteristics Program (SSCP), was utilized for a parametric study on the influence of the main form parameters on heave and pitch performance for the British Ship Research Association (BSRA) trawler series of geometrically related forms. From the results of this study an optimum form has been indicated and its geometrical features defined.
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Dong, Yan Qiu, e Weixue Lin. "Hydroelasticity and Wave Loads for a Full-Form Ship with Shallow Draft". Journal of Ship Research 36, n. 03 (1 settembre 1992): 280–85. http://dx.doi.org/10.5957/jsr.1992.36.3.280.
Testo completoAbstract (sommario):
A shallow-draft full-form ship is a particular type of ship with a breadth-to-draft ratio higher than is conventional. To investigate the characteristics of such full forms in response to hull vibrations induced by waves, a special computer program based on the hydroelasticity theory of ships has been developed. In addition, an experimental investigation using a segmented elastic-keel model of the ship has been carried out in order to verify the theoretical calculations. It is found from calculation of the wave loads that the dynamic responses of this specific hull form cannot be accurately predicted by strip theory. It is concluded therefore that hydroelasticity theory should be used in the design of the hull structure.
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BOGDANOWICZ, Artur, e Tomasz KNIAZIEWICZ. "Simulation of concentrations harmful compounds from main ships propulsion engine cooperating with a fixed pitch propeller in dynamic states". Combustion Engines 178, n. 3 (1 luglio 2019): 51–55. http://dx.doi.org/10.19206/ce-2019-309.
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The article presents a mathematical model of a marine propulsion system and a computer program based on the LabVIEW environ-ment. For a purpose of model construction, a ships hull resistance was identified and an approximation equations of the Wageningen institute for ship propellers were used. The ships motion equations were used to build the propulsion system model. On the basis of conducted tests of Sulzer 6AL20 / 24 marine engine, a map of concentrations harmful compounds was created in various load state and transferred to a computer program.
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Chirica, Ionel, e Elena-Felicia Beznea. "A Numerical Model for Torsion Analysis of Composite Ship Hulls". Mathematical Problems in Engineering 2012 (2012): 1–17. http://dx.doi.org/10.1155/2012/212346.
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A new methodology based on a macroelement model proposed for torsional behaviour of the ship hull made of composite material is proposed in this paper. A computer program has been developed for the elastic analysis of linear torsion. The results are compared with the FEM-based licensed soft COSMOS/M results and measurements on the scale simplified model of a container ship, made of composite materials.
Tesi sul tema "Hull (Computer program)"
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Alshraideh, Mohammad. "Use of program and data-specific heuristics for automatic software test data generation". Thesis, University of Hull, 2007. http://hydra.hull.ac.uk/resources/hull:12387.
Testo completoAbstract (sommario):
The application of heuristic search techniques, such as genetic algorithms, to the problem of automatically generating software test data has been a growing interest for many researchers in recent years. The problem tackled by this thesis is the development of heuristics for test data search for a class of test data generation problems that could not be solved prior to the work done in this thesis because of a lack of an informative cost function. Prior to this thesis, work in applying search techniques to structural test data generation was largely limited to numeric test data and in particular, this left open the problem of generating string test data. Some potential string cost functions and corresponding search operators are presented in this thesis. For string equality, an adaptation of the binary Hamming distance is considered, together with two new string specific match cost functions. New cost functions for string ordering are also defined. For string equality, a version of the edit distance cost function with fine-grained costs based on the difference in character ordinal values was found to be the most effective in an empirical study. A second problem tackled in this thesis is the problem of generating test data for programs whose coverage criterion cost function is locally constant. This arises because the computation produced by many programs leads to a loss of information. The use of flag variables, for example, can lead to information loss. Consequently, conventional instrumentation added to a program receives constant or almost constant input and hence the search receives very little guidance and will often fail to find test data. The approach adopted in this thesis is to exploit the structure and behaviour of the computation from the input values to the test goal, the usual instrumentation point. The new technique depends on introducing program data-state scarcity as an additional search goal. The search is guided by a new fitness function made up of two parts, one depending on the branch distance of the test goal, the other depending on the diversity of the data-states produced during execution of the program under test. In addition to the program data-state, the program operations, in the form of the program-specific operations, can be used to aid the generation of test data. The program-specific operators is demonstrated for strings and an empirical investigation showed a fivefold increase in performance. This technique can also be generalised to other data types. An empirical investigation of the use of program-specific search operators combined with a data-state scarcity search for flag problems showed a threefold increase in performance.
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Abu, Hashish Nabil. "Mutation analysis of dynamically typed programs". Thesis, University of Hull, 2013. http://hydra.hull.ac.uk/resources/hull:8444.
Testo completoAbstract (sommario):
The increasing use of dynamically typed programming languages brings a new challenge to software testing. In these languages, types are not checked at compile-time. Type errors must be found by testing and in general, programs written in these languages require additional testing compared to statically typed languages. Mutation analysis (or mutation testing) has been shown to be effective in testing statically (or strongly) typed programs. In statically typed programs, the type information is essential to ensure only type-correct mutants are generated. Mutation analysis has not so far been fully used for dynamically typed programs. In dynamically typed programs, at compile-time, the types of the values held in variables are not known. Therefore, it is not clear if a variable should be mutated with number, Boolean, string, or object mutation operators. This thesis investigates and introduces new approaches for the mutation analysis of dynamically typed programs. The first approach is a static approach that employs the static type context of variables to determine, if possible, type information and generate mutants in the manner of traditional mutation analysis. With static mutation there is the danger that the type context does not allow the precise type to be determined and so type-mutations are produced. In a type-mutation, the original and mutant expressions have a different type. These mutants may be too easily killed and if they are then they represent incompetent mutants that do not force the tester to improve the test set. The second approach is designed to avoid type-mutations. This approach requires that the types of variables are discovered. The types of variables are discovered at run-time. Using type information, it is possible to generate only type-correct mutants. This dynamic approach, although more expensive computationally, is more likely to produce high quality, difficult to kill, mutants.
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Wong, Pak Keung Patrick. "Assessing the effectiveness of the programme, Higher Diploma in Computer Studies offered by the City University of Hong Kong : an application of the 'CIPP' evaluation model". Thesis, University of Hull, 2002. http://hydra.hull.ac.uk/resources/hull:11089.
Testo completoAbstract (sommario):
This study evaluated the programme Higher Diploma in Computer Studies offered by the City University of Hong Kong. The evaluation aims to ascertain the effectiveness of the programme curriculum in accordance with the industry needs and requirements. This is a descriptive study, which utilizes Stufflebeam's (1971) context, input, process, and product (CIPP) evaluation model. Context evaluation serves planning decisions by helping to determine what needs are to be addressed and by defining the objectives for an educational programme. Input evaluation serves structuring decisions by helping to determine what resources are available and what alternative strategies for the programme should be considered. Process evaluation serves implementing decisions by determining how well the plan is being implemented and identifying possible revisions needed. Product evaluation serves recycling decisions by determining the results that were obtained, both intended and unintended and assessing how well the initially identified needs have been met. Questionnaires were developed to obtain information needed for the four types of evaluations from stakeholders of the programme. They were the employers of the programme graduates, the programme graduates, the current students, and the teachers of the programme. The findings from this study revealed that the programme is still in great demand in the Hong Kong Society, the programme is producing the right kind of graduate for the job market, and the programme objectives have been met accordingly. This study has also identified some operational aspects needing improvement. The programme should not position itself as a terminal qualification, but some form of bridging programme should be developed to allow graduates to further pursue a degree level qualification.
Libri sul tema "Hull (Computer program)"
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Tyndall, M. B. An analysis of an implicit factored scheme for simulating shock waves. Ascot Vale, Vic: Materials Research Laboratory, 1988.
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Canada. Defence Research Establishment Atlantic. Modhll: A Program For Modifying Computer Representations of Ship Hulls. S.l: s.n, 1986.
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Smith, Donald R. SUBHUL, submarine pressure hull finite element model generator user's manual. Dartmouth, N.S: Defence Research Establishment Atlantic, 1992.
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Canada. Defence Research Establishment Atlantic. Scrap: A Computer Program For Elastic Strength Analysis and Equivalent Beam Modelling of Ship Hulls. S.l: s.n, 1986.
Cerca il testo completoCapitoli di libri sul tema "Hull (Computer program)"
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Joswig, Michael, Georg Loho, Benjamin Lorenz e Benjamin Schröter. "Linear Programs and Convex Hulls Over Fields of Puiseux Fractions". In Mathematical Aspects of Computer and Information Sciences, 429–45. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-32859-1_37.
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Brun, Christophe, Jean-François Dufourd e Nicolas Magaud. "Formal Proof in Coq and Derivation of an Imperative Program to Compute Convex Hulls". In Automated Deduction in Geometry, 71–88. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-40672-0_6.
Testo completoAtti di convegni sul tema "Hull (Computer program)"
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Pullen, S. R., e J. F. Wellicome. "A PC Based Hull Surface Design Program". In Computer Aided Design for Small Craft 2. RINA, 1988. http://dx.doi.org/10.3940/rina.casc.1988.11.
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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.
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Martin, David E., e Robert F. Beck. "PCSAIL, A Velocity Prediction Program for a Home Computer". In SNAME 15th Chesapeake Sailing Yacht Symposium. SNAME, 2001. http://dx.doi.org/10.5957/csys-2001-010.
Testo completoAbstract (sommario):
An Excel Velocity Prediction Program has been developed to allow for rapid evaluation of yacht performance at the initial design stage. The required input consists of only the basic hull and sail dimensions. Empirical equations, based on these basic dimensions, are used for initial estimates of required hull parameters. As the design progresses the user can easily replace these default values with refined estimates or actual values. Because of its simplicity, and short turn around time, the program has been used as a teaching aid at the University of Michigan. Reconstruction of the program, PCSAIL, may be made with equations and other information provided in the Appendix. The Excel "Solver" has been found to be a reliable means of finding the equilibrium boat speed and heel angle. It seeks the maximum boat speed by adjusting the sail flattening factor, F, and reef, R, and the lateral location of the "movable crew." In the case of a hinged centerboard, or dagger- board, it will also adjust the draft for maximum boat speed. For sloop rigs the program will also take in the jib and set the spinnaker, at the appropriate wind angle, in order to gain maximum boat speed. The program plots the speed "polar," and velocity made-good, and determines the tacking angles.
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Farmer, J., L. Martinelli e A. Jameson. "YACHT97: A Fully Viscous Nonlinear Free-Surface Analysis Tool for IACC Yacht Design". In SNAME 12th Chesapeake Sailing Yacht Symposium. SNAME, 1995. http://dx.doi.org/10.5957/csys-1995-005.
Testo completoAbstract (sommario):
A novel free-surface computer program, used to calculate the viscous flow field about a full configuration sailing yacht, is presented. The numerical techniques incorporated into the computer program - YACHT97 - facilitate accurate quantification of the residuary and the frictional drag components through the use of a "moving" computational grid which conforms to the exact wetted surface area of the hull. Use of a full field approach, whereby the entire flow domain is discretized, permits the simulation of the boundary layer and wavemaking interaction as well as the onset of vortex structures which appear downstream of lift producing appendages. A recently implemented free-surface discretization permits the bow wave evolution to proceed to the near-breaking point. Computed results include comparisons between the inviscid and viscous flowfields about a bare-hull configuration and a full configuration with keel and rudder appendages.
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Park, Kyung Duk, Yong Kwan Chung, Young Sik Jang, Hyun Soo Kim e David Molyneux. "Development of Hull Forms for a 190,000 DWT Icebreaking Ore Carrier". In ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2011. http://dx.doi.org/10.1115/omae2011-49499.
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This paper describes the development of three candidate hull forms for 190,000 DWT ore carrier for operation in ice covered water. It builds on Hyundai Heavy Industries expertise in ore carrier design, and discusses some of the changes required for operation in heavy ice conditions. The overall concept was to have a target speed of 6 knots in land fast ice 1.7m thick and 15 knots in open water. Three candidate bow shapes were designed and analyzed, based on a common stern arrangement. The development of the hull form included three methods of predicting the performance of the ships in ice. Empirical analysis was carried out for all three hulls, based on experience gained from model experiments on bulk carrier hull forms in ice. Numerical analysis was carried out on all three bow shapes using a computer program (based on the discrete element method) to simulate the interaction between the ship and the ice. Physical model experiments were carried out for resistance and propulsion in level ice, pack ice and ridges on the selected design. As a result of the model experiments, the selected bow shape was modified to reduce its resistance in ice. The improved performance of the modified hull was confirmed with additional numerical simulations.
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Taravella, Brandon M., e Kyle E. Marlantes. "A Segmented Model Test of a Container Ship in Head Seas". In SNAME 30th American Towing Tank Conference. SNAME, 2017. http://dx.doi.org/10.5957/attc-2017-0017.
Testo completoAbstract (sommario):
Dynamic global hull girder response is an important part of the structural design of a ship, especially one with significant length and bow flare. Experimental studies were conducted at the University of New Orleans’ towing tank where a segmented model of a containership was tested in head seas and zero speed. Bending strain at 3 locations along the model’s hull was measured. The results showed peak sagging bending moment that is approximately 25% larger than the peak hogging bending moment at midship. Minor differences were found between positive heave amplitude and negative heave peaks. The results of the experiment were also compared to an “in-house” non-linear quadratic strip theory computer program. The experimental results compared quite well with the numerical results. The results of the experiments and computer program indicate that the dynamic bending moment response is predominantly a second-order effect and linear predictions are not sufficient.
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Bryson, Edward, Bruce W. T. Quinton e Claude Daley. "Probable Ice Impact Locations and Magnitudes on a Naval Hull Form in Forward Transit Through Marginal Ice Zones". In ASME 2023 42nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/omae2023-104854.
Testo completoAbstract (sommario):
Abstract Operational capability assessment of ships in the Arctic have traditionally focused on icebreaking hull forms. The classification of these capabilities resulted in the development of the International Association of Classification Societies (IACS) Unified Requirements for Polar Ships, which requires the hull structure to withstand a predetermined glancing bow impact. The assumptions made when developing the Polar Class Rules, such as the collision with a thick and semi-infinite multiyear ice floe, slow speeds, and a glancing bow impact on an icebreaking bow shape, are not always valid when assessing the operational capabilities of non-icebreaking hull forms. The ex-HMCS IROQUOIS was simulated in forward transit through marginal ice zones using the computer program “GEM” to study the location and magnitude of probable ice loads. The collision model was validated using the DDePS case 2a collision scenario (glancing collision on the bow). The model was simulated transiting forward at different speeds through ice regimes with varying identified parameters of interest, namely concentration, ice floe size distribution, and ice floe thickness. The observed results show most of the high magnitude ice impacts for this naval hull form occurred at or near the stem, and only a few high magnitude impacts on the bow shoulder. This contrasts to an earlier study using GEM where an icebreaking hull form in forward transit through a marginal ice zone experienced a plurality of high magnitude impacts along the bow shoulder. The main reason for the difference is the shape of the bow, with the naval hull form being markedly slender with much lower normal frame angles. These results suggest that both stem and bow shoulder impacts are of importance when assessing the operational capability of naval hull forms in marginal ice zones.
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Maskew, Brian, e Frank DeBord. "Upwind Sail Performance Prediction for a VPP including “Flying Shape” Analysis". In SNAME 19th Chesapeake Sailing Yacht Symposium. SNAME, 2009. http://dx.doi.org/10.5957/csys-2009-007.
Testo completoAbstract (sommario):
A coupled aerodynamic/structures approach is presented for predicting the flying shape and performance of yacht sails in upwind conditions. The method is incorporated in a flow simulation computer program, and is part of an ultimate objective for a simultaneous aeroelastic/hydro analysis in a Dynamic Velocity Prediction Program (DVPP), that will include a 6DOF motion solver, and at some point could include calculations in waves. The time-stepping aerodynamic module uses an advanced vortex lattice method for the sails and a panel method with special base separation treatment to represent the abovewater part of the hull and mast. A coupled inverse boundary layer analysis is applied on all surfaces including both sides of each sail membrane; this computes the skinfriction drag and the source displacement effects of the boundary layers and wakes, including bubble and leeside “trailing-edge” type separations. . At each step, the computed aerodynamic pressure and skin-friction loads are transferred to a coupled structures module that uses a network grid of tension “cords” in each sail membrane, each cord representing a collection of fiber “strings”. The solution of a structural equilibrium matrix provides the displacements needed to achieve balance between the aerodynamic and tension loads at each grid point as the shape iterations proceed. Details of the methodology used are presented and comparisons of predicted aerodynamic forces to wind tunnel results and an existing VPP sail model are provided. In addition, predictions are compared to some simple experiments to demonstrate the aerodynamic/structural coupling necessary to predict flying shape. Finally, an outline is given for incorporation of this methodology into the planned Dynamic Velocity Prediction Program.
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Milgram, Jerome H., Donald B. Peters e D. Noah Eckhouse. "Modeling IACC Sail Forces by Combining Measurements with CFD". In SNAME 11th Chesapeake Sailing Yacht Symposium. SNAME, 1993. http://dx.doi.org/10.5957/csys-1993-010.
Testo completoAbstract (sommario):
A sailing dynamometer with a 42% scale model of an International America's Cup Class rig is used to measure sail forces and moments in actual sailing conditions. The sailing dynamometer is a 35-foot boat containing an internal frame connected to the hull by six load cells configured to measure all the forces and moments between the frame and the hull. All sailing rig components are attached to the frame, so that the sail forces are measured. Sail shapes in use are determined by computer-interfaced video. Computational fluid dynamics performed on the measured shapes provides the induced drag. This allows the measured drag to be decomposed into induced and form-and-parasitic components, which is necessary for generating a mathematical sail force model for a velocity prediction program (VPP). It is shown that VPP results using these new sail force coefficients are in better agreement with actual performance than are VPP results based on traditional sail force coefficients.
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Lee, S. J., M. H. Kim, D. H. Lee e Y. S. Shin. "The Effects of Tank Sloshing on LNG Vessel Responses". In ASME 2007 26th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2007. http://dx.doi.org/10.1115/omae2007-29665.
Testo completoAbstract (sommario):
The coupling and interactions between ship motion and inner-tank sloshing are investigated by a potential-viscous hybrid method in time domain. For the time domain simulation of vessel motion, the hydrodynamic coefficients and wave forces are obtained by a potential-theory-based 3D diffraction/radiation panel program in frequency domain. Then, the corresponding simulations of motions in time domain are carried out using the convolution-integral method. The liquid sloshing in a tank is simulated in time domain by a Navier-Stokes solver. A finite difference method with SURF scheme assuming the single-valued free surface profile is applied for the direct simulation of liquid sloshing. The computed sloshing forces and moments are then applied as external excitations to the ship motion. The calculated ship motion is in turn inputted as the excitation for liquid sloshing, which is repeated for the ensuing time steps. For comparison, we independently developed a 3D panel program for linear inner-fluid motions and it is coupled with the vessel motion program in the frequency domain. The developed computer programs are applied to a barge-type FPSO hull equipped with two partially filled tanks. The time-domain simulation results show reasonably good agreement when compared with MARIN’s experimental results. The frequency-domain results qualitatively reproduce the trend of coupling effects but the peaks are in general over-predicted. It is seen that the coupling effects on roll motions appreciably change with filling level. The most pronounced coupling effects on roll motions are the shift or split of peak frequencies. The pitch motions are much less influenced by the inner-fluid motion compared to roll motions.
Rapporti di organizzazioni sul tema "Hull (Computer program)"
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West, Harry, e Mike Gallo. The National Shipbuilding Research Program. 1989 Ship Production Symposium, Paper No. AP: Design Through Manufacture: A Computer Aided Advisor for the Manufacture of Submarine Hulls. Fort Belvoir, VA: Defense Technical Information Center, settembre 1989. http://dx.doi.org/10.21236/ada453645.
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