scholarly journals Preliminary Comparative Investigations on Ballistic Properties of Intermediate Cartridges

2020 ◽  
Vol 11 (4) ◽  
pp. 27-44
Author(s):  
Dawid Goździk ◽  
Bartosz FIKUS ◽  
Jacek KIJEWSKI
Keyword(s):  
Drag Coefficient ◽  
Research Methods ◽  
Projectile Velocity ◽  
Preliminary Results ◽  
Ballistic Properties ◽  
Ballistic Test

The preliminary results of comparative investigations on intermediate cartridges were presented in this paper. The research focused mainly on the adopted assumptions and verification of research methods. Pressure ballistic test barrels, manufactured according to NATO EPVAT standards, were used for tests. The pressure courses of propellant gases in the barrel and the projectile velocity at four points of the bullet trajectory were measured. The pressure impulses, R100 parameter at 50 m and average bullet drag coefficient were calculated for each type of cartridge. The results allowed for a preliminary ballistic comparison of the most popular types of intermediate cartridges.

scholarly journals LOADS ON WIND TURBINES ACCESS PLATFORMS WITH GRATINGS

2011 ◽  
Vol 1 (32) ◽  
pp. 65
Author(s):  
Thomas Lykke Andersen ◽  
Peter Frigaard ◽  
Michael R Rasmussen ◽  
Luca Martinelli
Keyword(s):  
Drag Coefficient ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Large Scale ◽  
Peak Load ◽  
Multiplication Factor ◽  
Preliminary Results ◽  
Different Types ◽  
The Many ◽  
Large Scale Tests

The present paper deals with loads on wind turbine access platforms. The many planned new wind turbine parks together with the observed damages on platforms in several existing parks make the topic very important. The paper gives an overview of recently developed design formulae for different types of entrance platforms. Moreover, the paper present new results on loads on grates based on both drag coefficient measurements and preliminary results on slamming from large scale tests. As expected both investigations show that platforms with grates give a significant reduction in the loads compared to closed plate platforms. The grate multiplication factor, defined as the peak load on the grate platform relative to the peak load on a closed plate platform was found approximately equal to the solidity of the grate.

The Ballistic Performance of Multi-Layer Kevlar Fabrics Impregnated with Shear Thickening Fluids

2015 ◽  
Vol 782 ◽  
pp. 153-157 ◽  
Author(s):  
Yan Wang ◽  
Shu Kui Li ◽  
Xin Ya Feng
Keyword(s):  
Particle Size ◽  
Coupling Effect ◽  
Shear Thickening ◽  
Silica Particles ◽  
Ballistic Performance ◽  
Shear Thickening Fluid ◽  
Aramid Fabric ◽  
Shear Thickening Fluids ◽  
Ballistic Properties ◽  
Ballistic Test

This study investigates the ballistic penetration performance of aramid fabric impregnated with shear thickening fluid. The ballistic test was conducted at impact velocity of 445 m/s, and three types of shear thickening fluids prepared with silica particles of different sizes (200nm, 340nm and 480nm) are involved. The results demonstrate an enhancement in ballistic properties of fabric due to the impregnation of shear thickening fluids. The fabrics with smaller particle size show better ballistic performance. Microscopic observation of aramid fabric reveals that shear thickening fluids with smaller silica particles have a better adhesion on and between yarns, enhancinging the coupling effect between yarns. The corresponding mechanism was discussed in the paper.

scholarly journals Fragmentation of Millimeter-Size Hypervelocity Projectiles on Combined Mesh-Plate Bumpers

2017 ◽  
Vol 2017 ◽  
pp. 1-11
Author(s):  
Aleksandr Cherniaev ◽  
Igor Telichev
Keyword(s):  
Numerical Study ◽  
Orbital Debris ◽  
Aluminum Plate ◽  
Projectile Velocity ◽  
Two Component ◽  
Ballistic Properties ◽  
Unmanned Spacecraft ◽  
Metallic Meshes ◽  
Aluminum Mesh ◽  
Positive Results

This numerical study evaluates the concept of a combined mesh-plate bumper as a shielding system protecting unmanned spacecraft from small (1 mm) orbital debris impacts. Two-component bumpers consisting of an external layer of woven mesh (aluminum or steel) directly applied to a surface of the aluminum plate are considered. Results of numerical modeling with a projectile velocity of 7 km/s indicate that, in comparison to the steel mesh-combined bumper, the combination of aluminum mesh and aluminum plate provides better fragmentation of small hypervelocity projectiles. At the same time, none of the combined mesh/plate bumpers provide a significant increase of ballistic properties as compared to an aluminum plate bumper. This indicates that the positive results reported in the literature for bumpers with metallic meshes and large projectiles are not scalable down to millimeter-sized particles. Based on this investigation’s results, a possible modification of the combined mesh/plate bumper is proposed for the future study.

scholarly journals Controlled vocabularies and tags: An analysis of research methods

NASKO ◽  
2011 ◽  
Vol 3 (1) ◽  
pp. 23 ◽  
Author(s):  
Margaret E. I. Kipp
Keyword(s):  
Research Methods ◽  
Controlled Vocabulary ◽  
The Other ◽  
Social Tagging ◽  
Controlled Vocabularies ◽  
Preliminary Results ◽  
Bibliographic Records ◽  
Subject Headings ◽  
Author Keywords ◽  
Library Websites

Social tagging has become increasingly common and is now often found in library catalogues or at least on library websites and blogs. Tags have been compared to controlled vocabulary indexing terms and have been suggested as replacements or enhancements for traditional indexing. This paper explored tagging and controlled vocabulary studies in the context of earlier studies examining title keywords, author keywords and user indexing and applied these results to a set of bibliographic records from PubMed which are also tagged on CiteULike. Preliminary results show that author and title keywords and tags are more similar to each other than to subject headings, though some user or author supplied terms do match subject headings exactly. Author keywords tend to be more specific than the other terms and could serve an additional distinguishing function when browsing.

The O–C diagrams of minor planets − a new approach to modelling the rotation

1999 ◽  
Vol 173 ◽  
pp. 185-188
Author(s):  
Gy. Szabó ◽  
K. Sárneczky ◽  
L.L. Kiss
Keyword(s):  
Error Analysis ◽  
Time Dependence ◽  
Theoretical Work ◽  
Minor Planet ◽  
Minor Planets ◽  
New Approach ◽  
Preliminary Results ◽  
Ccd Observations

AbstractA widely used tool in studying quasi-monoperiodic processes is the O–C diagram. This paper deals with the application of this diagram in minor planet studies. The main difference between our approach and the classical O–C diagram is that we transform the epoch (=time) dependence into the geocentric longitude domain. We outline a rotation modelling using this modified O–C and illustrate the abilities with detailed error analysis. The primary assumption, that the monotonity and the shape of this diagram is (almost) independent of the geometry of the asteroids is discussed and tested. The monotonity enables an unambiguous distinction between the prograde and retrograde rotation, thus the four-fold (or in some cases the two-fold) ambiguities can be avoided. This turned out to be the main advantage of the O–C examination. As an extension to the theoretical work, we present some preliminary results on 1727 Mette based on new CCD observations.

Cyclic Evolution of Sunspots: Gleaning New Results from Old Data

2000 ◽  
Vol 179 ◽  
pp. 163-165
Author(s):  
S. K. Solanki ◽  
M. Fligge ◽  
P. Pulkkinen ◽  
P. Hoyng
Keyword(s):  
Sunspot Number ◽  
Sunspot Cycle ◽  
Preliminary Results ◽  
Butterfly Diagram

AbstractThe records of sunspot number, sunspot areas and sunspot locations gathered over the centuries by various observatories are reanalysed with the aim of finding as yet undiscovered connections between the different parameters of the sunspot cycle and the butterfly diagram. Preliminary results of such interrelationships are presented.

Systematic effects in observed parallaxes

1978 ◽  
Vol 48 ◽  
pp. 31-35
Author(s):  
R. B. Hanson
Keyword(s):  
Error Estimates ◽  
Zero Point ◽  
Absolute Zero ◽  
Apparent Magnitude ◽  
Coherent System ◽  
Preliminary Results ◽  
General Catalogue ◽  
Systematic Effects ◽  
New Evidence ◽  
Right Ascension

Several outstanding problems affecting the existing parallaxes should be resolved to form a coherent system for the new General Catalogue proposed by van Altena, as well as to improve luminosity calibrations and other parallax applications. Lutz has reviewed several of these problems, such as: (A) systematic differences between observatories, (B) external error estimates, (C) the absolute zero point, and (D) systematic observational effects (in right ascension, declination, apparent magnitude, etc.). Here we explore the use of cluster and spectroscopic parallaxes, and the distributions of observed parallaxes, to bring new evidence to bear on these classic problems. Several preliminary results have been obtained.

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