Number Of Dents Research Articles

Differences in physicochemical properties and structure of red sorghum starch: Effect of germination treatments

AbstractBackground and ObjectivesGermination has been extensively studied, but the changes in different starch components have not yet been entirely elucidated. The aim of this study was to assess the effects of germination on the starch composition, physicochemical properties, and structure of red sorghum seeds.FindingsGermination of red sorghum starch led to decreased amylose, water absorption, and syneresis, but increased oil absorption, solubility, and swelling power. The freeze–thaw stability of germinated sorghum starch improved. However, the starch paste exhibited thinning under shear, suggesting its gel structure was susceptible to damage. The starch's peak viscosity and breakdown value increased significantly with the increase in germination time, whereas the setback value decreased. Germination treatment did not alter the chemical structure of the starch, but it increased the porosity and the number of dents on the surface of starch granules. Notably, the in vitro digestibility of the starch increased significantly after germination.ConclusionsThe germination treatment of red sorghum affected the structure and physicochemical properties of the isolated starch to some extent.

Surface Corrugations and Layer Thickness Dependent Frictional Behavior of MoS2 – A Computational Study

2D materials are at the core of nano/micro-electro-mechanical systems (MEMS/NEMS). However, surface corrugations are unavoidable in 2D materials because of operational inefficiencies involved in the synthesis procedures. Engineering the mechanical properties of the 2D materials are highly sought-after because they are the driving mechanism behind the nanodevices' functionality. So far, most related works focus on single planar 2D materials, i.e., Graphene. The existing Transient Metal Dichalcogenide (TMD) analyses do not include torque implications on the frictional force and multiple different variables simultaneously. In this work, we have combined the two aspects, i.e., surface irregularities with the need for tuning the mechanical properties. We have studied tuning the frictional properties of Molybdenum Disulfide (MoS2) by reactive molecular dynamics (rMD) modeling, which is further analyzed by density functional theory (DFT) code. We analyzed BADER charge and molecular orbitals by DFT code. The MoS2 layer(s) are indented by using an in-built library in Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) to obtain different conformations of the system. We considered multiple cases, i.e., varying number of the layers (1-3), the number of dents (2-8), the radius of each dent (12-24 Å), and the pattern of the dents (in-line and zigzag). Next, we performed MD simulations to pass a hemispherical diamond probe across the indented surface to measure all spatial components of the reactional force and torque experienced by the probe during its movement. The probe is modeled by spring support on six axes to stabilize the movement. In total, 16 different systems are studied with different combinations of the dent's radius, pattern, quantity, and the number of layers. We hypothesize the frictional force experienced by the probe is affected by the materials’ geometry, both adjacent to and along the line of contact. Our torque plots validate our hypothesis. The major fluctuations in torque plots correlate with the fluctuations in force plots after neglecting the data noise. Our approach is useful for any other 2D materials. Our results provide insight into the characterization of the frictional dependence on locale surface corrugations.

Experimental investigation of buckling of dented cylindrical shells under axial compression

The results of unique experimental studies of buckling of dented axially compressed unstiffened cylindrical shells are provided in the suggested paper. The dimple-like geometrical imperfections of different shape, size, deflection amplitude, and number of dents were created on cylindrical shells before axial loading. The initial deflection amplitude varied in the wide range, up to several shell thicknesses. In all cases the plateaus were discovered on the buckling load initial deflection diagrams. Corresponding axial loads were close to local lower buckling loads of perfect shells. These loads are defined as minimum values of axial force when the post-buckling equilibrium states of the perfect structure with one or several dimples exist. It was shown that the lower local buckling loads slightly depend on geometrical imperfections and therefore can be used for estimation of design buckling load of the structure. Over 50 specimens were tested. Pre-buckling and post-buckling behavior of imperfect shells was studied.

An Experimental Study on the Concentration and Shape of Dents Caused by Spherical Metallic Particles in EHL Contacts©

An experimental study of metallic contaminant effects on surface indentation in EHL contacts is presented. Particles are initially spherical and are composed of M50 high-carbon steel powder. Their diameter ranges from 32 to 40 μm. An original lubrication system with a controlled level of contamination was built. The contaminant distribution and concentration are measured on-line by an automatic particle counter. Tests are conducted on a two-disk machine with different operating conditions. Particles may travel through the EHL contact only one time, the lubricant flow being used only once. The oil is a synthetic one qualified under the MIL-L-23699 specification. An optical profilometer is used to describe the indent topography and a CCD video camera to count the number of dents. The test bench is described and the experimental procedure is presented. Specific tests were performed to quality the contamination bench. The combined effects of particles concentration and test duration on dent distribution were studied. Some results on the shape and concentration of indents versus operating conditions are presented. It is shown that over the range of test conditions considered, the number of indents on the raceways can be estimated from the particle concentration in the oil bulk. This leads to the conclusion that the particle entry ratio is close to one, i.e., the concentration of particles inside the EHL contact is close to those in the bulk. Presented at the 52nd Annual Meeting in Kansas City, Missouri May 18–22, 1997

Method of determining the critical loads for longitudinally compressed reinforced cylindrical shells

At the beginning the minimal natural vibrations frequencies were determined for all the reinforced shells. A resonance method was used; the shell was excited by a vibrator with 4.7 g mass. It is obtained for the minimal natural vibrations frequencies that they equal 106 Hz, 103 Hz, 97 Hz, and 70 Hz, respectively. The numbers of deflection waves in the circumferential direction (n) equal 4, 5, 6, and 9, respectively, for these shells. Stability tests were performed on the shells in two steps. First smooth shells were tested and then ribs were glued on and tests of reinforced shells were conducted. The critical load and the number of dents over the perimeter were determined. It is detected that the total buckling of reinforced shells was accompanied by wave formation with the number of waves n = 4-5 in the circumferential direction for shells i and 2, n = 6 for shell 3 and n = 9 for shell 4 and a number of half-waves m = i in the longitudinal direction for all the shells considered, which is in agreement with the above-mentioned numbers of waves for the minimal natural vibrations frequencies.

Surface morphology of oxygen-implanted wafers

The surface morphology of SIMOX wafers implanted at 180 keV with doses of 0.4–2.2 ⊠ 101816O+ cm−2 in a temperature range of 400–700 °C has been investigated using transmission electron microscopy (TEM) replica and cross-sectional TEM (XTEM) techniques. Wafer temperature during oxygen implantation strongly affects the morphology. A number of dents are formed on the surface of wafers implanted at temperatures higher than 510 °C with a dose of 1.8 ⊠ 1018 cm−2. Increasing the wafer temperature causes the dents to grow. The dents disappear by a high-temperature anneal of 1260 °C after the implantation. It is found that oxygen implantation through a 50-nm-thick screen oxide film prevents dent formation. A model explaining the dent formation and dent growth is also proposed.

An Energy Method for Relative Estimates of Hail Intensity

A simple instrument was developed to estimate hail energy input per unit area. By using certain simplifying assumptions, the instruments have been calibrated in the laboratory to permit estimates of hail energy input from measurements of dent size and number of dents per unit area. Special effects noted during field use of a large number of these instruments are described. It is estimated that, although the absolute error in estimating hail- energy input may exceed 300 per cent, the error in comparative measurements of hail energy input by this equipment is approximately 50 percent.

基本的なピーニングによる凹痕の大きさ・密度と疲労強度との関係

The authors carried out a reversed bending fatigue test of flat specimens shot-peened under the most fundamental conditions; that is peened with almost perfect sphere shots made of very rigid metal and as uniformly as possible.Results obtained are as follows:1) Excess of impact force causes the increase of dent's size, resulting in the drop of fatigue strength.2) Number of dents per unit area or density of peening has the critical value beyond which the fatigue strength will begin to decrease. This critical value is larger for smaller dents than for larger dents.3) The most desirable result is obtained for a combination of smaller dent and larger density of peening.4) Results described in 1) & 2) may be regarded as the so-called over-peening.