Defining Patterns and Behaviours of Forward Spatter Gunshot Misting

The purpose of this research was to study forward-spatter misting patterns by shooting a firearm through a chamber of blood encased in ballistic gel to determine if there is a relationship between bloodstain pattern size as a function of distance and orientation. There is a lack of research on forward spatter, blood travelling in the direction of a bullet, as most studies focus on back spatter, blood travelling in the opposite direction of a bullet. A bullet was fired through ballistic gel containing a blood chamber, depositing bloodstains onto a large sheet of butcher paper as the target surface. In total, there were 34 trials. The distances observed were 10, 20, 40, and 80 cm, the angles tested were 30°, 60°, and 90°. The orientation between the ballistic gel and paper target varied. A criterion was established to observe the overall area and symmetry of the bloodstain patterns. Statistical analyses indicated a negative linear relation relationship between the bloodstain pattern size and the paper’s angle and distance (R2 = 0.78) and the vertical symmetry of the bloodstain (R2 = 0.87). The orientation between the ballistic gel and paper target can impact the bloodstain pattern’s symmetry and size.

Enhanced Photocurrent Response Speed in Charge-Density-Wave Phase of TiSe2-Metal Junctions

Group IVB transition metal dichalcogenides (TMDCs) have attracted significant attention due to their predicted high charge carrier mobility, large sheet current density, and enhanced thermoelectric power. Here, we investigate the...

Route to high-$$T_{c}$$ superconductivity of $$\hbox {BC}_{{7}}$$ via strong bonding of boron–carbon compound at high pressure

We have analyzed the compositions of boron–carbon system, in which the $$\hbox {BC}_{{7}}$$ BC 7 compound is identified as structural stability at high pressure. The first-principles calculation is used to identify the phase diagram, electronic structure, and superconductivity of $$\hbox {BC}_{{7}}$$ BC 7 . Our results have demonstrated that the $$\hbox {BC}_{{7}}$$ BC 7 is thermodynamically stable in the diamond-like $$P{\bar{4}}m2$$ P 4 ¯ m 2 structure at a pressure above 244 GPa, and under temperature also. Feature of chemical bonds between B and C atoms is presented using the electron localization function. The strong chemical bonds in diamond-like $$P{\bar{4}}m2$$ P 4 ¯ m 2 structure are covalent bonds, and it exhibits the s–p hybridization under the pressure compression. The Fermi surface shape displays the large sheet, indicating that the diamond-like $$P{\bar{4}}m2$$ P 4 ¯ m 2 phase can achieve a high superconducting transition temperature ($$\hbox {T}_{{c}}$$ T c ). The outstanding property of $$\hbox {BC}_{{7}}$$ BC 7 at 250 GPa has manifested very high-$$\hbox {T}_{{c}}$$ T c of superconductivity as 164 K, indicating that the carbon-rich system can induce the high-$$\hbox {T}_{{c}}$$ T c value as well.

COMPENSATION OF SPRINGBACK IN LARGE SHEET METAL FORMING

A precise production of sheet metal parts has always been a main goal in press shops. Highest quality demands are required especially in automotive production. Unfortunately, even today, the production is not optimal due to an ineffective approach to the springback compensation. Springback results in geometrical shape inaccuracies of the obtained product. Based on the current approach, excessive time and financial costs emerge due to corrections on the press tools. However, these corrections do not always lead to a better accuracy of the stampings. The main objective of the research is to design a modified solution of the current approach. The modified solution is designed as a methodology with a focus on the analysis and compensation of the springback with a help of a numerical simulation. To achieve the main goal, smaller sub-goals are employed. These sub-goals, or rather experiments, mainly focus on parameters, which, more or less, influence the springback phenomenon. The designed methodology is verified with real car body parts and is carried out with a help of the department of the press tools design in ŠKODA AUTO, a.s. There, the methodology is used for improving the accuracy of the stamping process of the car body parts and for improving the quality of the final product.

Numerical investigation for the flexible stretch-stamp forming process of sheet metal

Flexible stretch-stamp forming is a sheet metal forming method derived from flexible stretch forming and multi-point forming, aimed at solving wrinkling defects of large skin parts especially with complex curvatures, prone to occur in the later type of forming processes. To help understand the forming principle and forming characteristics of flexible stretch-stamp forming, a large sheet metal part with wavelike surface was selected as the study object and extensive numerical simulations have been conducted using a general commercial finite element software. The main processing parameters of pre-stretching force and wrapping force, respectively, exerted by horizontal and sloping cylinders on forming quality were investigated in detail. Finally, experiments were conducted to estimate the forming performances of flexible stretch-stamp forming.

Distribution of Encrusting Foraminifera At San Salvador, Bahamas: a Comparison By Reef Types and Onshore−offshore Zonation

Foraminifera attached permanently to hard substrates have received relatively little research attention in distributional studies compared to free-living specimens. Because attached (encrusting) species are commonly found on hard substrata, such as coral rubble, and they are sensitive to environmental variables controlled by water depth and distance from shore, these species can be useful in paleoecologic research. This study examined the distribution of encrusting foraminifera found at the outer Bahamian island of San Salvador to describe onshore-to-offshore zonation and to characterize foraminiferal assemblages found in different reef types. Cobbles were collected along two transects on the leeward side of the island and at numerous locations on the windward side, including a bank barrier reef and the eastern platform edge. Encrusting foraminifera found on the undersides of cobbles were quantified and identified by taxa, morphotype, and taphonomic grade. Significant differences were found in the distribution of encrusting foraminiferal species across the carbonate platform, based on both counts of individuals and area of substrate covered. The zonation was particularly evident between platform-top and platform-margin assemblages. Nearshore assemblages were dominated by well-preserved Homotrema rubrum. Patch reefs, especially those found further from shore, were characterized by a relatively diverse assemblage with prominent Planorbulina spp. whereas bank barrier reefs were dominated by H. rubrum, often with Gypsina plana. Platform-margin assemblages were the most distinct because they were dominated by large, sheet-like G. plana, with other taxa being small, sparse, and poorly preserved.