Hull Size Research Articles

Simplified optimal design of a tension leg platform (TLP)

This brief note deals with a method for designing the hull of a TLP by a minimum criterion. The very complicated problem of finding the best size of a standard TLP hull with regards to its weight is carried out by adopting a simplified model, depending only on two design variables, which is optimized under the same constraints considered for the effective structure. Subsequently, the dimensions of the hull are found imposing the constancy of the total buoyancy, and using again a minimum weight criterion. The results agree rather well with the cases known.

Extraction of Anthocyanin Pigments from Purple Sunflower Hulls

ABSTRACTThe anthocyanin pigments in hulls of purple sunflower seeds were extracted using three solvent systems, 50:1:49 ethanol‐acetic acid‐water (EAW), 0.01M acetic acid (AAc), or water containing SO2. Solvent, extraction time, size of ground hulls, pH of extracting solvent, hulls/solvent ratio, and concentration of SO2 in water, were investigated. All were significant factors affecting yield of extracted anthocyanins. EAW and SO2 were more effective extractants than AAc. Optimum conditions from response surface optimization for the extraction with sulphurous water were: SO2 at 200 mg/L, hull size 20 mesh, extraction time 5 min at 22°C, and solvent/hulls ratio = 20.

Kinder, gentler average-case analysis for convex hulls and maximal vectors

While the derivations of precise asymptotic estimates found in the mathematical literature are not easily accessible to the non-specialist, there are rather simple arguments for deriving rougher "big-theta" bounds on the expected size of random convex hulls. These arguments are presented, then applied to verify a recently published conjecture on the expected number of maximal vectors among a set of random points chosen from a ball. A summary of recent progress follows. Results relevant for analyzing algorithms are emphasized.

The convex hull of the zeros of a random polynomial

In this paper we present empirical results on the size and location of the convex hull formed by the zeros of a random polynomial.

イネのlhs(葉化穎不稔)を用いた穎の規制を受けない粒大のF_2,F_3変異

イネのlhs(葉化穎不稔)を用いた穎の規制を受けない粒大のF_2,F_3変異

Fundamental Studies on Underwater Sound Radiated from a Vibrating Ship Hull

In preceding reports, authors studied on the two and three dimensional sound radiation problem and sound scattering problem from a vibrating elastic shells. Introducing the analytical and numerical solutions, we clarified the property of these phenomena.At the low frequencies, the radiation pattern is always dipole and not affected by the hull shapes, vibration modes and exciting points. On the other hand, at the high frequencies, the vibration mode of the shell near the exciting point becomes so complicated that the accuracy of numerical analysis will become worse due to the limitation of the element discretization or CPU time.In this report, we show the methods of approximate analysis of the low and high frequency regions. At the low frequencies, namely, when the sound wavelength becomes very long as compared with the hull size, we show that the low frequency approximation gives a good agreement with the exact solutions at ka<0.1, where k is the wave number of the time harmonic exciting force and a is the typical radius of the hull. At the high frequencies, namely, when the sound wavelength becomes short as compared with the hull bending wavelength, we propose a high frequency approximation in which a hull can be assumed as a infinite flat plate covered one side with the water. Then we show that the high frequency approximation gives a good agreement with the exact solution at the region where the frequency is larger than the critical frequency.

Model tests on ice-rubble size and ship resistance in ice rubble

Described here are the results of model tests on resistance to ship-hull motion through a thick layer of ice rubble; layer thickness was 45% of hull draft. The tests were aimed to elucidate the influences of ice-rubble size on ice-rubble resistance. It was found that as ice-rubble size increased so did the resistance encountered by the test hull. However, it was also found that a layer of mush ice produced a greater resistance than did layers comprised of ice blocks. A layer comprised of both mush ice and ice blocks produced a resistance intermediate to layers comprised of either mush ice or ice blocks. Ship resistance generally increased with increasing ship speed. However, the influences of ship speed and ice-rubble size on the contributing resistance processes were found to be somewhat more complex. For example, the frictional resistance experienced by the parallel midbody of the test hull initially decreased with increasing ship speed, when the ice rubble was comprised of ice blocks which were small compared to layer thickness and hull size. The frictional resistance subsequently increased then decreased again with increasing ship speed. When the layer was comprised of relatively large ice blocks, frictional resistance increased to a maximum value then decreased with increasing ship speed. Generally, larger frictional resistance occurred for the layers comprised of larger ice rubble. In accordance with the relative sizes of ice rubble and ship hull, and with hull speed, the variations in frictional resistance can be explained in terms of a layer behaving as either a granular medium or as a viscous fluid. An additional aim of the study was to verify the existence of a thrust due to the ascension of submerged ice at a hull's stern. The existence of a stern thrust had been postulated by Kitazawa and Ettema (1985). The present study indicates that a relatively weak stern thrust may occur, but its magnitude is negligibly small compared to other resistance forces.

Corrosion Protection Guidelines for Aluminum Hulls

Marine aluminum alloys are used in boat hulls and structures because of their corrosion resistance, strength, weldability, light weight, and ease of fabrication. Years of successful service of a wide variety of vessels have proven aluminum's suitability. However, in order to take maximum advantage of the metal's inherent resistance to corrosion, consideration should be given to the details of a vessel's design, fabrication, and operation in order to optimize its performance. This paper provides the designer, builder, and operator with some guidelines. The complexity of these subjects makes it necessary to generalize. The information is applicable to a range of small and medium-size craft, approximately 30 to 120 ft, but not to any specific type or size of hull. Larger craft with aluminum hulls or deckhouses and smaller riveted craft may require individual consideration beyond the scope of this document.

The Seattle Harbor Craft: A Case Study of the Design Process

This paper describes steps in the design process of a high-speed fireboat for Seattle Harbor. The principal requirements that controlled the design concept are outlined along with a parametric study that was performed to identify the optimum hull size. The arrangements, structure, materials selection, and machinery are described as well as the boat's fire fighting/rescue mission and performance characteristics.

Increase of Warping Rigidity in Open Sections of a Containership by Stiffening Plates

Distributions of warping stress and deformation of modules with open-section and longitudinal stiffening plates were determined by a finite-element program. Eleven models of various stiffnesses and configuration but under the same torsional moment were studied. The loading and overall hull size are close to a containership of 38 000-ton loading capacity. The prismatic thin-walled beam analysis was performed on a model to compare the results from the finite-element approach. It has been found that the warping rigidity can be effectively increased by installing plates along the axis of the ship. The maximum warping stresses, which are usually found at the hatch corners of the wing boxes, are evaluated and compared.

Role of the Hull in the Ripening of Rice Plant : VII. Effects of supplying of silica and potassium during reproductive growth stage on the form and function of hulls

Previously, and were shown to accumulated in the hulls of fertile grains than those of sterile ones. Based on these findings, effects of supplying of and during reproductive growth stage on the form and function of hulls were further studied. And the effects of top dressing of new fertilizer potassium silica were also investigated. 1. Silica. (a) No significant difference in the number of spikelets on the primary branches of panicle was detected between no-supplying and supplying plot, whereas the number of spikelets on the secondary branches was increased by the supplying of silica. (b) Ripening percentage and weight of 1000 kernels increased significantly by supplying of silica. This might be due to the increase in the size of hulls and the decrease in the occurrence of malformed grains. (c) The content in hulls increased greatly by the supplying of silica. 2. Potassium. Supplying of during reproductive growth stage gave mostly the same effect as those of silica, however the difference in content was very small between no-supplying and supplying plot. 3. New fertilizer potassium silica The top dressing of silica, a new fertilizer, at initial stage of spikelets differentiation enhanced the ripening percentages and weight of 1000 kernels due to the decrease in the occurrence of malformed grains. As shown above, and affect the form and function of hulls and were very useful and important to increase ripening.

コンテナ船, Ro/Ro船の輸送性能分析

Container- and Ro/Ro-vessels are featured especially by the reduction of terminal time as a result of containerized cargo handling of lift-on/lift-off and roll-on/roll-off method, respectively. This paper analyzes the transportation energy efficiency of both vessels built in Japan so far, with paying attention to the feature mentioned above. Firstly the hull resistance characteristics are analyzed. In the same as car ferry, both vessels have the property being able to separate the hull function into buoyant support and cargo vessel. This property permits the hull form to have less resistance than general cargo ships. The performance level of hull resistance is same for all container-and Ro/Ro-vessels except the large, high speed container vessels with the speed above 26 knots and the displacement above 50, 000 tons, of which hull form are different because of the Panamax limit, and result in inferior level by about 30%. It is pointed out, therefore, that the enlargement of hull size over the Panamax limit is excessive as for the container ship. Secondly the cargo performance, which is indicated by the payload-to-displacement ratio, is analyzed. The payload of container- and Ro/Ro-vessels can be regarded as the carrying number of containers. The above ratio of container vessel is mainly determined by two factors of deadweight-to-displacement ratio and container number on deck loading. The deadweight-to-displacement ratio raises undesirably with speed. While it cannot be improved by the increase of displacement. Therefore the high speed container ship above 26 knots cannot have necessarily good cargo performance in spite of the design for increase of container number on deck loading. The cargo performance of the Ro/Ro ship is worse by two times than the container ship due to the roll-on/roll-off cargo handling method. This demerit sets off inevitably the merit that the Ro/Ro ship can handle cargoes without the special equipment ashore.

Studies on the Characters of the Improved Semi-Dwarf, High-Yieding Indica Rice Varieties : I. Characters of the ripening from the viewpoint of sink, source, and reserve carbohyrates

Ripening characters were compared between the japonica and the improved semi-dwart high-yielding indica varieties. The results obtained are as follows: 1. At the heading stage, there was a tendency that improved indica varieties had more spikelets per m2. Especially, the receptive capacity (sink) of dry matter per m2, which is represented by the number of spikelets per m2 × weight of a hull, was larger in improved indica than in japonica varieties. 2. Improved indica varieties had smaller LAI (source) irrespective of growth duration not only in early variety group but also in middle and late variety group. 3. Accordingly, there was a tendency that improved indica varieties had smaller leaf area per spikelet at the heading stage. In addition, their hull size was large considering leaf area per spikelet, resulting in lower ripening percentage. As a result, there was no significant difference in yield between improved indica and japonica varletles. 4. There was no correlation between grain weight and leaf area per spikelet at the heading stage, but was a high positive correlation between grain and hull weight. 5. At the heading stage, among the varieties whose nitrogen contents in leaf blade were almost same, the improved indica varieties showed lower starch and higher sugar contents in culm and leaf sheath than japonica varieties. 6. Among the japonica varieties, the very early varieties whose yields were low had smaller LAI at the heading stage considering their number of spikelets per m2.

The Significance of the Hull Size of Rice Plant as a Factor Determining Kernel Weight

The Significance of the Hull Size of Rice Plant as a Factor Determining Kernel Weight

Transfer of training as a function of task difficulty in a complex control situation.

Abstract : Two submarines, differing with respect to their dynamic response characteristics as a function of differences in hull size, were simulated at each of two speeds (slow and fast). Four groups of 20 subjects were trained on a depth-keeping task, one group on each of 4 hull-speed combinations. Following training, 3 subgroups of 5 subjects from each group were tested on the other 3 hull-speed conditions, with the remaining 5 subjects tested on the same system. This was done to determine the degree to which training on any 1 of the 4 systems transfers to the other 3 systems. It was found that, on the basis of mean time on target scores per five-trial block, the more difficult systems to control were those with the longer control lags. These were the small hull at slow speed and large hull at slow systems. It was also found that training on the most difficult control system, the large hull at slow speed system, produced generally better transfer effects than did training on any other system. (Author)

The Influence of Aircraft Gross Weight upon the Size and Weight of Hulls and Fuselages

In this paper an attempt has been made to trace the influence of gross weight, as the accepted measure of size, upon the dimensions of hulls and fuselages and from this, to evaluate the probable trend of the weights of these components with increasing gross weight.During the past few years the size and gross weight of aircraft have rapidly increased and there appears at the moment little, if any, structural limit upon the size and gross weights attainable, since it can be shown that the percentage weights of hulls and fuselages tend to decrease as size increases.