Prediction of healing efficiency of carbon-based nanocomposites under modified environment

This study investigates an analysis of the healing behavior of carbon-based nanocomposites by using the finite element (FE) method and provides the quantitative healing values based on the efficiency with respect to the volume, C[Formula: see text]V[Formula: see text]/V[Formula: see text]. An approximation of the geometrical relationship on the profile was considered, and the results compared with the model were used to estimate the healing efficiency based on the initial open profiles. In this model, it contains the interface elements between damaged crack faces. We adjust their sizes and stiffness of elements to compare the profiles with a geometrical equation. We propose that the results of their efficiencies can be compared with the strength of the healing elements that depend on the size of healed volume by the approximation.

A Novel Three-Dimensional Vector Analysis of Axial Globe Position in Thyroid Eye Disease

Purpose. To define a three-dimensional (3D) vector method to describe the axial globe position in thyroid eye disease (TED).Methods. CT data from 59 patients with TED were collected and 3D images were reconstructed. A reference coordinate system was established, and the coordinates of the corneal apex and the eyeball center were calculated to obtain the globe vectorEC→. The measurement reliability was evaluated. The parameters ofEC→were analyzed and compared with the results of two-dimensional (2D) CT measurement, Hertel exophthalmometry, and strabismus tests.Results. The reliability ofEC→measurement was excellent. The difference betweenEC→and 2D CT measurement was significant (p=0.003), andEC→was more consistent with Hertel exophthalmometry than with 2D CT measurement (p<0.001). There was no significant difference betweenEC→and Hirschberg test, and a strong correlation was found betweenEC→and synoptophore test. When one eye had a larger deviation angle than its fellow, its corneal apex shifted in the corresponding direction, but the shift of the eyeball center was not significant. The parameters ofEC→were almost perfectly consistent with the geometrical equation.Conclusions. The establishment of a 3D globe vector is feasible and reliable, and it could provide more information in the axial globe position.

Mid-Profile Design and Numerical Simulation for Supercavitating Vehicle

Based on elliptic curve equation and G.V.Logvinovich cavity geometrical equation, the mid-profile of supercavitating vehicle was researched. The author uses Navier-Stokes equation and k-ε turbulence equation to simulate the designed geometry shape depending on structure grid. The beneficial results show that the mid-profile design for supercavitating vehicle is able to integrate and control the partial attached cavitating flow, and enable the cavity proximate shape to the elliptic shape. As a result, the cavitating reflow phenomenon influenced by tail nozzle contraction at the rear of the supercavitating vehicle could be mitigated, and in a certain range of curvature, the drag reduction performance is better than that of the cylindrical method. The research is able to effectively increase the fullness of the supercavitating vehicle in the mid-profile, and so it is quite superiority.

Air-hydrate crystals in deep ice-core samples from Vostok Station, Antarctica

Microscopic observation of air-hydrate crystals was carried out using 34 deep ice-core samples retrieved at Vostok Station, Antarctica. Samples were obtained from depths between 1050 and 2542 m, which correspond to Wisconsin/Sangamon/Illinoian ice. It was found that the volume and number of air-hydrate varied with the climatic changes. The volume concentration of air-hydrate in the interglacial ice was about 30% larger than that in the glacial ice. In the interglacial ice, the number concentration of air-hydrate was about a half and the mean volume of air-hydrate was nearly three times larger than that in the glacial-age ice. The air-hydrate crystals were found to grow in the ice sheet, about 6.7 × 10−12cm3year-1, in compensation for the disappearance of smaller ones. The volume concentration of air-hydrate was related to the total gas content by a geometrical equation with a proportional parameter α. The mean value of α below 1250 m, where no air bubbles were found, was about 0.79. This coincided with an experimentally determined value of the crystalline site occupancy of the air-hydrate in a 1500 m core obtained at Dye 3, Greenland (Hondoh and others, 1990). In the depth profile of calculated α for many samples, α in the interglacial ice was about 30% smaller than that in the glacial-age ice.

Air-hydrate crystals in deep ice-core samples from Vostok Station, Antarctica

Microscopic observation of air-hydrate crystals was carried out using 34 deep ice-core samples retrieved at Vostok Station, Antarctica. Samples were obtained from depths between 1050 and 2542 m, which correspond to Wisconsin/Sangamon/Illinoian ice. It was found that the volume and number of air-hydrate varied with the climatic changes. The volume concentration of air-hydrate in the interglacial ice was about 30% larger than that in the glacial ice. In the interglacial ice, the number concentration of air-hydrate was about a half and the mean volume of air-hydrate was nearly three times larger than that in the glacial-age ice. The air-hydrate crystals were found to grow in the ice sheet, about 6.7 × 10−12 cm3 year-1, in compensation for the disappearance of smaller ones. The volume concentration of air-hydrate was related to the total gas content by a geometrical equation with a proportional parameter α. The mean value of α below 1250 m, where no air bubbles were found, was about 0.79. This coincided with an experimentally determined value of the crystalline site occupancy of the air-hydrate in a 1500 m core obtained at Dye 3, Greenland (Hondoh and others, 1990). In the depth profile of calculated α for many samples, α in the interglacial ice was about 30% smaller than that in the glacial-age ice.

Application of a geometrical volume equation to species with different bole forms

Stem analysis of 20 Abiesbalsamea (L.) Mill., 68 Piceamariana (Mill.) B.S.P., 19 Piceaglauca (Moench) Voss, 31 Populustremuloides Michx., and 37 Betulapapyrifera Marsh. revealed form variation between species. A volume equation based on the paracone (a geometrical solid midway between a paraboloid and a cone) estimated individual tree volume within 10% of the true volume (at the 95% confidence level) for all species. The input variables required were total height and diameter at a relative height of 0.2 for Betulapapyrifera and 0.3 for the other four species. If breast-height diameter was used, the effect of form variation on the accuracy of volume prediction was more pronounced. In this case, the geometrical equation modified for each species according to the average centre of gravity provided more consistently accurate volume estimates than either the paracone equation or Honer's transformed variable equation. For all species, the diameter measurement position was more critical than the version of the geometrical equation selected.

The inextensible string

An object to which we were all introduced at an early stage in mechanics is the inextensible string. This appears frequently without causing much trouble, but there is one type of problem which, in my opinion, stands apart from the rest, and which certainly caused me a lot of trouble. Such a problem is when impulses are given to a system which includes an inextensible string, as, for example, a system consisting of two rigid parts joined by a string. If an impulse is applied to one of these parts, an impulsive tension (T) may be set up in the string, which, in turn, gives an impulse to the other part. One new quantity, T, has appeared, and one equation in addition to the ordinary dynamical equations is thus required before the problem of finding the change in motion of the system can be solved. It is at this stage that opinions can differ, for this extra equation depends essentially upon what concept of an inextensible string is being adopted, and there is more than one. The usual procedure is to employ a “geometrical equation” based upon the argument that the two ends must have equal component velocities in the line of the string as long as the string is taut. This seems almost obvious when described in such general terms, and is followed by such eminent writers as Routh and Loney, amongst others. I suggest, however, that this method implies a concept which leads to results contrary to common-sense and to everyday experience. This is best illustrated by a simple example.