Half Breadth Research Articles

Effects of half breadth to draught ratio of hull under water surface on bilge-keel roll damping component

Roll amplitudes of parametric roll in regular head waves are sometimes underestimated by motion calculations including Ikeda's roll damping prediction method, especially for the case of the large roll amplitude caused by high wave height. In this case, generally the ship has significant relative draught changing because of its heave and pitch. It may be said that the effects of the change in relative draught on roll damping is significant. However, in Ikeda's prediction method, the bilge-keel component which is the largest component of total roll damping does not take the effects of draught. As the effects of draught, there are at least two related significant effects on the bilge-keel roll damping component not fully considers for developing Ikeda's prediction method. They are the effects of underwater hull aspects (: half breadth to draught ratio) and the free surface effects. In this study, as a first attempt, the effects of draught on the bilge-keel component are investigated experimentally and numerically by using a 2-dimensional model. And a prediction model of the effects of draught on bilge-keel component to collect Ikeda's prediction method is proposed. Moreover, the calculated results by the proposed method are compared with some measured data including the effects of draught and its validity is confirmed.

Analysis of random antireflective structures fabricated by silver dewetting to enhance transmission

The random antireflective structures are modeled by the analysis of the random morphology distribution. According to the effective medium theory, the transmission of the antireflective structure is calculated by dividing the structure into multilayer, and the dependence on parameters of the subwavelength is analyzed in detail. In the single-variable condition, etching depth, half breadth of distribution, and median of distribution get a positive correlation with the transmittance where the etching depth plays a most important part in enhancing the transmittance, whereas the angle of structures gets a negative correlation. The experimental results coincide well with the calculation and analysis. The analysis offers a theory guidance to fabricate random subwavelength antireflected structures using metal dewetting.

Unified Strength Model for Square and Circular Concrete Columns Confined by External Jacket

When the corner radius ratio ρ is defined as 2r∕b (corner radius divided by half breadth of column), circular and sharp cornered square columns are just two special cases when ρ=1 and 0, respectively. It is quite logical that a confined concrete strength model for columns with a corner radius should degenerate into a model for circular and sharp cornered square columns when ρ=1 and 0, respectively. However, this is not the case in any of the existing models, except for the early one by Mirmiran et al. in 1998. Extensive experimental testing on fiber-reinforced polymer (FRP)-confined concrete columns that have a continuous variation of ρ from 0 to 1 has been undertaken by the writers. Based on the experimental findings, a rational procedure is proposed for developing a unified strength model for FRP-confined concrete columns with an arbitrary corner radius. A comprehensive database has been established by collecting all of the available experimental results from the open literature for evaluation of the un...

A study on fatigue damage modeling using neural networks

Fatigue crack growth and life have been estimated based on established empirical equations. In this paper, an alternative method using artificial neural network (ANN) -based model developed to predict fatigue damages simultaneously. To learn and generalize the ANN, fatigue crack growth rate and life data were built up using in-plane bending fatigue test results. Single fracture mechanical parameter or nondestructive parameter can’t predict fatigue damage accurately but multiple fracture mechanical parameters or nondestructive parameters can. Existing fatigue damage modeling used this merit but limited real-time damage monitoring. Therefore, this study shows fatigue damage model using backpropagation neural networks on the basis of X-ray half breadth ratioB/B 0 , fractal dimensionD f and fracture mechanical parameters can estimate fatigue crack growth rateda/dN and cycle ratioN/N f at the same time withinengineering limit error (5%).

Position of the teeth on the edentulous atrophic maxilla

For prosthetic treatment of strongly atrophic alveolar wall, some biometric methods have been developed. The measurements taken from plaster cast models of 230 edentulous, average 29.9 years, and 125 dentulous post-menopausal women were correlated. In the edentulous maxilla the sagittal position of canine teeth can be determined by the oral edge of incisive papilla. The transverse position of canine teeth was on the outer edge of the alveolar wall because of the extensive loss of buccal alveolar bone. On the incisor area the facial surfaces of the central incisors were determined by the oral edge of incisive papilla and the distance was about twice the length of the papilla. The sagittal position of the first premolars was one-third and the first molars two-thirds the length of the palate from the plane of the labial edge of incisive papilla. The transverse position of the premolars and molars was determined by the scar-line, which is a cord-like elevation or track on the alveolar mucosa after extractions of the teeth. According to the comparative method, the position of the scar-line differed from the lingual gingival margin line and was situated about half breadth of the tooth in a buccal direction from it. The transverse position of premolar and molar in the edentulous maxilla is about the middle of the scar-line in a facio-buccal direction. In the setting of the artificial teeth, the facial surfaces of these teeth should be on average 5.0-6.0 mm sideways from the scar-line, whilst the total bilateral breadth of the alveolar wall in the sulcus area was on average 1.0-2.0 mm larger.

A Study on Fatigue Crack Growth and Life Modelling using Backpropagation Neural Networks.

Fatigue crack growth and life is estimated by various fracture mechanical parameters but affected by load, material and environment. Fatigue character of component without surface notch cannot be e valuated by above-mentioned parameters due to microstructure of in-service material. Single fracture mechanical parameter or nondestructive parameter cannot predict fatigue damage in arbitrary boundary condition but multiple fracture mechanical parameters or nondestructive parameters can Fatigue crack growth modelling with three point representation scheme uses this merit but has limit on real-time monitoring. Therefore, this study shows fatigue damage model using backpropagatior. neural networks on the basis of X-ray half breadth ratio B/ fractal dimension and fracture mechanical parameters can predict fatigue crack growth rate da/dN and cycle ratioN/ at the same time within engineering estimated mean error(5%).

Relation between fatigue damage and half-value breadth of X-ray diffraction lines in fatigue processes of carbon steels.

For annealed and prestrained carbon steels, the relation between the change in fatigue damage of the specimen surface and the value of half breadth of X-ray diffraction lines in the fatigue processes has been investigated. The place observed by a microscope is included in the area irradiated by X-ray. For annealed carbon steels the half-value breadth increases remarkably in the early period of stress cycles, while for prestrained steels, it decreases remarkably. The period of abrupt change in the half-value breadth corresponds to the period of abrupt change in the density of slip lines in both steels. In the process of the initiation and propagation of microcracks, the change in the half-value breadth is not marked.

An Application of Mathieu Function Expansions to Hull Form Improvement

Mathieu-function-expansion method is proposed for evaluating and improving performance of ship hull forms. Medium speed ships, the design Froude number somewhere between 0.20 and 0.25, are mainly discussed.The present method is based on minimum wave resistance theory (Maruo and Bessho, 1963) for infinite draft wall-sided ships. When the half breadth curve is expanded by Mathieu functions, the coefficient of the higher order term has by far the greater effect upon the value of the wave resistance than the coefficients of the lower order terms. Using this fact the performance of the ship hull form is evaluated from the standpoint of the wave resistance and the information, how to improve the ship hull form is gotton.The tank tests are carried out to verify it and the results show that the present method is very powerful for improvement of practical ship hull forms.

Relationship between Rolling Contact Fatigue and Residual Stress on Contact Surface

A rolling sliding contact fatigue test was conducted with the use of Ni-Cr-Mo-V steel discs (H=340HB, S=250HB) for marine main turbine's reduction gears and lubricating oil (No.200 turbine oil) at the soft-specimens slide-sweep ratio of -24% and 2100 rpm: and in the test, the X-ray diffraction techniques were used in obtaining the value of the residual stress on the contact surface where rolling fatigue pits were produced. The residual stresses closely related with; (a) the Herzian maximum pressure and the D-value (total surface roughness of the two discs/EHL minimum oil film thickness) under poorly lubricated conditions such as in D>1; (b) the repetition of contact at early stage of test. A change in the production of residual stress takes place with D=2 as boundary. In addition, the relation between pitting failure and the half breadth of distribution curve of diffraction strength is described.

Stress Measurement by Oscillation Technique of X-Ray Optical System

In order to make X-ray measurement of stress using oscillation technique, its optimum conditions were studied with respect to the grain size of the specimen and the geometrical conditions of the soller slit system. Investigation was also made of the influence that the oscillating angle, the oscillating speed and the time constant would have on the diffraction profiles or the stress determined by X-rays.The abnormality of diffraction profile of coarse grained specimen, caused by the geometrical conditions of the soller slit system, decreased by the oscillation of the X-ray optical system. And the number of grains, which contributed to the diffraction, increased by the oscillation technique. The diffraction profile obtained with the instrument became normal, when the range of oscillating angle was twice as large as the half breadth of the diffraction profile. And the peak position of diffraction profile could also be determined with ease.The periodic change of intensity was observed on the diffraction profile when the oscillation technique was used. This phenomenon was remarkable with the increase of incident angle ψ0. It was due to the difference of diffracted X-ray intensity for different angle in oscillation. When smaller oscillating angle than ±15°was chosen, however, the periodic change in intensity of the diffraction profile was kept sufficiently small under the time constant 8 or 16sec. which was what is generally used.The analytical results showed that the value of cosecθ obtained from the oscillation technique was not exactly proportional to that of sin2ψ. But the experimental results showed that the cosecθ-sin2ψ relations obtained in the oscillating condition became approximately linear. The stress value of Fe {211} determined by conventional sin2ψ method using the data of ±10° oscillating condition, appeared to be 4∼6% smaller than that obtained from the data of fixed condition. Sin2ψ method seems to be practically useful to determine the stress, even when the oscillation technique is adopted, supposing that the oscillating angle is not so large and the stress of the specimen is not so high.

Effects of Rolling on the Heat Transfer from Cango Oils of Tankers

A 1/50 scale model of side tanks of a tanker is used in this experiment to know effects of rolling on the heat transfer from shell walls. Results of the experiment are as follow.(1) The temperature of oil in the tank becomes uniforrn when rolling occurs.(2) The heat transfer coefficient increases almost linear according to the angle and frequency of rolling.(3) Fin effect of stiffeners is little, then their size and material affects little the heat transfer from stiffeners. They work mainly as mixers of oil in tanks.Empirical equations for increments in the heat transfer coefficient by rolling are given as, ΔNu=0.0160 Re0.942Pr1/3……for side shellΔNu=0.0155 Re0.910Pr1/3……for bottom shell where ΔNu=Δαl/λ and Re=2πbθl/ (Tν).(Δα : increment in heat transfer coefficient, l : stiffener space, λ : thermal conductivity, θ : rolling angle, b : half breadth of tank, T : rolling period, ν : kinematic viscosity.)

Role of Residual Stresses as Determined by X-Ray Diffractometry on Magnetic Properties of 4-79 Molybdenum Permalloys

AbstractResidual stresses in several batches of heat-treated 4-79 molybdenum Permalloy finished laminations were measured by X-ray diffraction technique. This involved determination of macrostresses from line shift of (331) reflection by the two-exposure diffractometric technique as well as the determination of microstresses from half breadth of the same line profile. It was observed that the residual stresses In all batches of laminations were small and the variations in residual stresses from one batch of laminations to another were not appreciable, considering the scatter in laminations within each individual batch. Simultaneous magnetic measurements showed considerable variation in magnetic properties from batch to batch; e.g., a five-fold variation in normalized hysteresis loop and a two-fold variation in the magnetic “softness” parameter. On subjecting individual batches of laminations to various thermal and thermomagnetic treatments below 650 C, considerable change in magnetic properties was achieved without significantly changing residual stresses. The variation in magnetic properties in finished laminations was ascribed to the difference in effective crystal anisotropy and uniaxial anisotropy caused by variations in thermal and thermomagnetic annealing treatments. The study showed that the variation was not due to any major variation in stress induced magnetostrietive anisotropy.

Plasma Oscillation of Electrons in Be, Mg, Al, Si, Ge, Sn, Sb and Bi

The plasma oscillation of electrons in Be, Mg, Al, Si, Ge, Sn, Sb and Bi has been studied using the method of energy analysis of electrons passed through thin foil of those solids. The energy loss value Δ E , the dispersion relation, i. e. the dependence of Δ E on the scattering angle θ, the angular dependence of the intensity, the half breadth of Δ E , and the cutoff scattering angle θ c (corresponding to the cutoff wave number k c ) were measured by the photometric method. The angular distribution of the intensity does not agree with θ -2 law given by Ferrell, but shows θ 1.6∼-1.7 dependence. The curvature of Δ E vs. θ curve for Be, Mg, Al and Si agree well with the theoretical values calculated by the free electron theory, but those for Ge, Sn and Sb are 20∼30% larger than the corresponding theoretical values, and that for Bi is twice as large as the latter. The half breadths of energy loss peak due to the plasma oscillation increase with increase in the scattering angle. Specimens of Ge were studied i...

Residual Stresses due to Butt Welding

The accuracy of stress measurement by X-rays has been improved remarkably through recent years. Active researches have been conducted in many laboratories, and as a result the measured stress values have come to the stage of giving a sufficient reliability. However, there still remain some problems which must be further investigated.In this study, as one of the application problems, the authors took up the problem of welding residual stresses. In connection with this subject, a number of studies have hitherto been made. But there have been few works so far that dealt with the residual stress distributions measured by the X-ray method.The test piece used was a mild steel plate (SS41) with the dimension of 140×70×4.5mm, and two pieces were butt welded together under the groove angle of 75°by an ordinary A C arc welder, forming a specimen of square type. The welding consisted of two passes on the surface and one pass of reinforcing bead on the back.The X-ray stress measurement was carried out by the film method using the Glocker, s technique of vertical and 45°oblique incidences. At first, CoKα beams were used, but the diffraction lines showed a considerable broadening. Therefore, CrKα radiation was utilized, and in this case fairly sharp diffraction lines were obtained. The distribution curves of diffraction intensity were drawn by an automatic recording microphotometer. The peaks of these curves were determined, for convenience' sake, by the method of half breadth at the half height. The residual stresses were calculated by the following formula, σ=(Δ⊥-Δ+)C⊥+The residual stresses were measured in two directions, parallel and perpendicular to the bead, at many points both on the surface and back, and the distribution curves of them were drawn. The results on the surface showed, in contrast to the ordinary results for the plate without a reinforcing bead, compressive residual stresses in the vicinity of the bead and tensile stresses near the edge in both cases of the measurements in the two directions. On the other hand, the results on the back were reverse to the above case. This effect of the reinforcing bead is worthy of note.For the measurement of welding residual stresses, the Gunnert method or the Mathar method has been widely utilized so far. Consequently, for the purpose of comparing the measured stress values, the Mathar method was also applied to the present specimens. The Mathar method consists of drilling a small hole in the sample and measuring the deformation around the hole. The drill used was of 6mm diameter, and for the measurement of strain four electric resistance wire gages with the gage length of 6mm were pasted on the specimen, each two being attached in the direction parallel and normal to the bead respectively. The calibration test was conducted a priori, and based on this result the residual stresses were calculated according to the formula given by Riparbelli. The Mathar method was applied, as before, to several points on the surface and back, and the results were compared with those of the X-ray method. The stress values obtained by the Mathar method showed a little scattering. On the whole, however, these values were a little smaller than those measured by the X-ray method. This result seems to be natural, since the stress value obtained by the Mathar method gives the average over the distance of the gage length in contrast to the local stress value measured by the X-ray method.Next, on the supposition of the stress repetition of an extremely low cycle as in the case of a boiler drum, the change in residual stresses due to the repeated stressing of a very low cycle was investigated. Another specimen with the dimension of 140×40×4.5mm, butt welded along the center line parallel to the short side of 40mm was prepared for this experiment.

溶接ジルコニウムにおける格子歪の回復について

The recovery of lattice strain in welded zirconium, 50% cold rolled, was studied on the basis of the change of half breadth of X-ray diffraction lines.The recovery of lattice strain of the c-axis direction in the welded and non-welded zones shows nearly the same rate in the isothermal recovery curve, particulary, at a high temperature. However, the recovery of the a-axis direction in the welded zone has retarded as compared to that in the non welded zone.Besides, recrystallized grains in the welded zone do not appear even by annealing at 800°C for 1 hr, whereas in the quenched zirconium showing a similar structure to the welded zone they are found by annealing at 600°C for 1 hr.From these results it can be understood that inhomogeneously dissolved oxygen and other gases during the welding play an important role in the recovery process as well as in the thermal expansion as previously reported by the authors.

Plane Stress of the Plate which has the Discontinuity Parts : 4th Report, The Case of the Cross-shaped Plate

In the preceding reports, we solved numerically and experimentally the plane stresses when the belt has a recutangular projection on one side. In this report, we calculate numerically for the cross-shaped plate by the same method as the preceding reports and find out the magnitude of the stress concentration of the edge stress for the various radius of curvature of the root in the cross-shaped plate. In consequence ; the stress concentration factor is proportional to √(a/ρ)= (a : half breadth of the plate, ρ : radius of the curvature of the root) and the stress concentration occurs at the point of constant ratio for various radius.

On the Tension in an Orthogonally Aeolotropic Strip with a Circular Hole

In this paper, the tension in an orthotropic strip with a circular hole, which has practical importance, is treated. The solution of the same subject for isotropic material, has been presented by R.C.J. Howland and lately improved by M. Isida to study the stresses in a strip with an elliptic hole by the use of orthogonal co-ordinates. In this paper, the same methods are adopted to express the free edge conditions at the rim of the strip and of the circular hole and the stresses are given in the form of the power series of λ which is the ratio of the radius of the circular hole to the half breadth of the strip.

Resonance Broadening of Caesium

The resonance broadening of homogeneous Cs vapor in absorption was studied by means of the contour method. The intensities were obtained via the method of "astigmatic photometry" by utilizing the astigmatism of the Rowland grating. The pressure of the homogeneous absorbing vapor ranged from ${10}^{\ensuremath{-}2}$ to 17.5 mm Hg. The half breadth $\ensuremath{\gamma}$ varied rather linearly with the number of atoms per unit volume, with $(\frac{{\ensuremath{\gamma}}_{1}}{N})\ifmmode\times\else\texttimes\fi{}{10}^{7}=1.45$, $(\frac{{\ensuremath{\gamma}}_{2}}{N})\ifmmode\times\else\texttimes\fi{}{10}^{7}$ for the $^{2}P_{\frac{3}{2}}$ and $^{2}P_{\frac{1}{2}}$ eomponents of the resonance lines, respectively. The average value of the ratio of half breadths $\frac{{\ensuremath{\gamma}}_{1}}{{\ensuremath{\gamma}}_{2}}$ was found to be 1.8. The experimental half-width $\ensuremath{\gamma}$ is found to be about 1\textonehalf{} times larger than that predicted by W. V. Houston. Below pressures of 10 mm Hg the lines exhibited symmetrical broadening according to the "dispersion" formula. At higher pressures indications of a violet and red asymmetry are present for the $^{2}P_{\frac{3}{2}}$ and $^{2}P_{\frac{1}{2}}$ components, respectively. A definite band on the red side of the $^{2}P_{\frac{3}{2}}$ and one on the violet side of the $^{2}P_{\frac{1}{2}}$ was observed.

On the Transverse Inclination of a Ship when the Helm is put over, or in a Similar Case

A ship is inclined inwardly toward the centre of a turning circle soon after the rudder is put over, and when she becomes to turn steadily, she inclines in the opposite side. In this paper, the inclinations of those two kinds are considered.The first inward heel is important for the safety of a ship when helmed over abruptly, and consequently for the determination of the time required to put the helm hard over, which is necessary to determine the capacity of the steering gear. Treating dynamically the motion of a ship helmed over, the expression for the maximum inward inclination is obtained as follows:θmax=θ0{1+Ts/πt0|sinπ/Tst0|}where θ0: static l heel angle due to the heeling moment caused by the transverse force on the rudder plate put hard over.Ts: natural period of the ship.T0: the time required to put the helm hard over.A similar motion of a ship occu s in an inclining experiment, and the conditions in order to avoid the free rolling, usually accompanied, are discussed. Additionally, the motion of a pendulum on board used in that experiment is investigated.Lastly, for the outward heeling angle in the stendy turning, the breadth of the ship must be considered, though neglected usually, and the new expression for it is got as follows:tanθ_??_tanθ1/1-b/dtanθ1where θ: the required angle of heel.θ1: the angle of heel which is usually taken, neglecting the effect of breadth.b and d: half breadth and draft of a ship respectively.Studying the effect of a bilge keel on the heeling quality experimentally, it is found that the bilge keel is very injurious to that quality in a turning condition.

Organic Media as Spectral Filters in the Ultraviolet1

Aqueous solutions of organic media were examined by the extinction point method, using a geometrical series of concentrations, in a search for media having high gradation of absorption in the ultraviolet region.Curves of log (concentration) against frequency ν of extinction point are shown for thirty-two compounds, grouped as to spectral region in which the curves have high slope. Five compounds had not been studied previously: gallic and tannic acids, aniline arsenate, arsanilic acid, and p-dichlorobenzene.The quantity a, the slope of the curve of log i against ν, is shown to be the sole significant factor in determining gradation of absorption. Media having rectilinear log i curves are shown to have constant gradation of absorption of a degree proportional to the slope of the curve.Curves of log b, log c, and log log 1/T are shown to have an invariant form, that of the curve of log i. It is shown that use of these curves locates directly the frequencies at which a is highest; leads to simple methods of testing Beer’s Law, of determining low solubility, and of finding “true half breadth” of absorption lines; and permits partially graphical solution of other absorption problems. The relations between the curve of a mixture of two solutes and the curves of the components are developed.The extinction point method is shown to have certain advantages over other methods because of the low value of transmittancy involved, and to be adequate for determination of a when a is high. A modification of it, involving use of a constant low transmittancy T, is suggested.