scholarly journals Application and Analysis of Discrete Fiber Probes in Determining Detonation Velocity of Microcharges

Micromachines ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1524
Author(s):  
Guodong Zhang ◽  
Yulong Zhao ◽  
Jing Sun
Keyword(s):  
Standard Deviation ◽  
Detonation Wave ◽  
Optical Fibers ◽  
Detonation Velocity ◽  
Initiation System ◽  
Experimental Apparatus ◽  
Discrete Fiber ◽  
Fiber Probes ◽  
Probe Spacing

This paper describes a method based on discrete fiber probes for measuring detonation velocity produced by microcharges. This method is simple to implement, scalable for multi-channel and requires minimal perturbation to the detonation wave. A simple experimental apparatus was established by using the oscilloscope, photodetectors, optical fibers, alignment device and initiation system. Four groups of experiments were carried out for analyzing the influence of probe spacing on detonation velocity. The experiment results suggest that a relatively appropriate distance between two adjacent fiber probes is 4 mm. In addition, the comparative experiments between ionization probes and fiber probes were performed, which shows that the standard deviation of detonation velocity obtained by fiber probes is smaller under the same measurement conditions. This research may be useful for the development of determining detonation velocity precisely of microcharges.

scholarly journals Nano- and Micropatterning on Optical Fibers by Bottom-Up Approach: The Importance of Being Ordered

2021 ◽  
Vol 11 (7) ◽  
pp. 3254
Author(s):  
Marco Pisco ◽  
Francesco Galeotti
Keyword(s):  
Optical Fiber ◽  
Optical Fibers ◽  
Self Assembly ◽  
Ordered Structures ◽  
Bottom Up ◽  
Photonic Structures ◽  
Fiber Technology ◽  
Optical Fiber Probes ◽  
Fiber Probes ◽  
Self Assembled

The realization of advanced optical fiber probes demands the integration of materials and structures on optical fibers with micro- and nanoscale definition. Although researchers often choose complex nanofabrication tools to implement their designs, the migration from proof-of-principle devices to mass production lab-on-fiber devices requires the development of sustainable and reliable technology for cost-effective production. To make it possible, continuous efforts are devoted to applying bottom-up nanofabrication based on self-assembly to decorate the optical fiber with highly ordered photonic structures. The main challenges still pertain to “order” attainment and the limited number of implementable geometries. In this review, we try to shed light on the importance of self-assembled ordered patterns for lab-on-fiber technology. After a brief presentation of the light manipulation possibilities concerned with ordered structures, and of the new prospects offered by aperiodically ordered structures, we briefly recall how the bottom-up approach can be applied to create ordered patterns on the optical fiber. Then, we present un-attempted methodologies, which can enlarge the set of achievable structures, and can potentially improve the yielding rate in finely ordered self-assembled optical fiber probes by eliminating undesired defects and increasing the order by post-processing treatments. Finally, we discuss the available tools to quantify the degree of order in the obtained photonic structures, by suggesting the use of key performance figures of merit in order to systematically evaluate to what extent the pattern is really “ordered”. We hope such a collection of articles and discussion herein could inspire new directions and hint at best practices to fully exploit the benefits inherent to self-organization phenomena leading to ordered systems.

Microfabricated Fiber Probe by Combination of Electric Arc Discharge and Chemical Etching Techniques

2012 ◽  
Vol 462 ◽  
pp. 38-41 ◽  
Author(s):  
Wan Maisarah Mukhtar ◽  
P. Susthitha Menon ◽  
Sahbudin Shaari
Keyword(s):  
Optical Fibers ◽  
Chemical Etching ◽  
Arc Discharge ◽  
Etching Rate ◽  
Electric Arc ◽  
Buffer Solution ◽  
Fiber Probe ◽  
Optical Fiber Probes ◽  
Electric Arc Discharge ◽  
Fiber Probes

In this study, optical fiber probes were fabricated by combination of electric arc discharge and chemical etching techniques. Size of tips diameters fabricated using different etching solutions were observed. When the optical fibers were pulled and heated by the electric arc discharge using a fusion splicer, fiber tips with few microns in diameter were obtained. To minimize the tips diameter, the pulled fiber probes were etched vertically for 10 minutes using two different etching solutions namely 49% HF and HF buffer solution (49% HF and 40% NH4F) with ratio of 2:1. A thick overlayer was added on top of the HF solution to prevent dangerous vapors escape to the environment. When the tapered part of the pulled fiber (FP1) was dipped into 49% HF solution, the diameter of tip was slightly decreased from 4.41μm to 1.31μm with etching rate of 5.17x10-3 μms-1. When the pulled fiber (FP2) was etched into HF buffer solution, the etching rate was increased up to 52.35% with the etching rate of 10.85x10-3μms-1. The tip diameter was reduced from 7.01μm to 468.9 nm in diameter. Combination of “heat and pull” technique with chemical etching by using HF buffer solution produced fiber probe with small tip diameter.

scholarly journals An electrical method of determining the velocity of detonation of explosives

1924 ◽  
Vol 105 (731) ◽  
pp. 282-298 ◽  
Keyword(s):  
Detonation Wave ◽  
Detonation Velocity ◽  
Detonation Pressure ◽  
Electrical Method ◽  
Vapour Density ◽  
Velocity Of Detonation ◽  
Set Up

When a layer of molecules in a mass of explosive detonates, the change is transmitted throughout the mass, and the velocity with which the transmission takes place is called the rate of detonation. It has been shown that the pressure p set up in the front of a detonation wave can be written p = velocity of detonation × velocity of vapour × density, so that explosives with high rates of detonation will have correspondingly high detonation pressures and consequently high destructive properties. A glance at the accompanying table [ see Robertson: 'J. C. S.,' vol. 119, p. 1 (1923)], which includes also values for the heat produced during detonation, will show that this is the case:- The pressure developed by tetryl is more than six times that developed by gunpowder, but the number of calories liberated at detonation by 1 gm. is only 1·8 times as great. The detonation pressure therefore depends not only on the amount of energy liberated, but also on the rate at which it is liberated. Rate of detonation becomes therefore at once one of the most important constants in explosive technology.

scholarly journals The EFP Formation and Penetration Capability of Double-Layer Shaped Charge with Wave Shaper

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4519
Author(s):  
Yakun Liu ◽  
Jianping Yin ◽  
Zhijun Wang ◽  
Xuepeng Zhang ◽  
Guangjian Bi
Keyword(s):  
Detonation Wave ◽  
Double Layer ◽  
Detonation Velocity ◽  
Incidence Angle ◽  
Shaped Charge ◽  
Experimental Simulation ◽  
Detonation Waves ◽  
Forming Process ◽  
Large Length ◽  
Overdriven Detonation

Detonation waves will bypass a wave shaper and propagate in the form of a horn wave in shaped charge. Horn waves can reduce the incidence angle of a detonation wave on a liner surface and collide with each other at the charge axis to form overdriven detonation. Detection electronic components of small-caliber terminal sensitive projectile that are limited by space are often placed inside a wave shaper, which will cause the wave shaper to no longer be uniform and dense, and weaken the ability to adjust detonation waves. In this article, we design a double-layer shaped charge (DLSC) with a high-detonation-velocity explosive in the outer layer and low-detonation-velocity explosive in the inner layer. Numerical and experimental simulation are combined to compare and analyze the forming process and penetration performance of explosively formed projectile (EFP) in DLSC and ordinary shaped charge (OSC). The results show that, compared with OSC, DLSC can also adjust and optimize the shape of the detonation wave when the wave shaper performance is poor. DLSC can obtain long rod EFPs with a large length-diameter ratio, which greatly improves the penetration performance of EFP.

MECHANISM OF DETONATION IN EXPLOSIVES

Geophysics ◽  
1944 ◽  
Vol 9 (1) ◽  
pp. 1-18 ◽  
Author(s):  
Robert W. Lawrence
Keyword(s):  
Shock Waves ◽  
Detonation Wave ◽  
Wave Front ◽  
Detonation Velocity ◽  
High Velocity ◽  
Hydrodynamic Theory ◽  
Detonation Waves ◽  
Energy Propagation ◽  
Low Velocity ◽  
Detonation Wave Front

Results of photographic work on the detonation of high explosives are presented and discussed in their relationship to the hydrodynamic theory of detonation. The two most important properties of an explosive are its strength and its detonation velocity. Methods for determining these quantities are described. A moving film camera of the rotating drum type is especially useful in determining detonation velocity and in studying the nature of detonation. The photographic results, which are illustrated by a number of pictures, are helpful in demonstrating various elements of the theory. These photographs illustrate the nature of detonation waves in explosives and of shock waves in air. The duration of the detonation waves in nitroglycerin and blasting gelatin is less than one millionth of a second and the duration of the shock waves produced by these explosives in air is of the same order. The high temperature of shock waves which is predicted by theory is confirmed by the intense luminosity shown in photographs. The relatively low temperature predicted for shock waves in liquids is similarly confirmed by the absence of luminous shock waves in water. Photographs are included showing the propagation of detonation from one cartridge of blasting gelatin to another across air gaps and water gaps. In the latter case no visible shock wave is produced in the water and the highly luminous after‐burning is eliminated. Calculated values of the detonation velocity for nitroglycerin, blasting gelatin and 60% gelatin dynamite are in approximate agreement with the experimentally determined values. Calculations indicate that pressures in the detonation wave may run as high as 140,000 atmospheres and temperatures to 4300°C. The shape of the detonation wave front in a high velocity explosive like blasting gelatin is apparently planar whereas in low velocity explosives it is convex. The actual mechanism of energy propagation in detonation is not clearly understood out probably involves activation of the explosive at the detonation wave front by high velocity products of the detonation which are projected forward at speeds even greater than the detonation velocity.

THE DETONATION VELOCITY OF AXIALLY CAVITATED CYLINDERS OF CAST DINA

1948 ◽  
Vol 26b (5) ◽  
pp. 435-440
Author(s):  
C. A. Winkler ◽  
M. Kirsch ◽  
G. Papineau-Couture
Keyword(s):  
Detonation Wave ◽  
Detonation Velocity ◽  
Photographic Record

A method is described, involving the use of the Jones and Lamson Pedestal Comparator, for estimating velocities of detonation from the photographic record obtained on a rapidly moving film. The increase in detonation velocity in cavitated charges is accompanied by the appearance of a luminous effect which moves down the cavity approximately 1.6 times faster than the detonation wave. Both the luminous effect and the increase in detonation velocity disappear when the cavity is filled with water.

scholarly journals Investigation of the initiating ability of conically shaped charges

2018 ◽  
pp. 69-76
Author(s):  
Roman Zakusylo
Keyword(s):  
Detonation Wave ◽  
Ammonium Nitrate ◽  
Detonation Velocity ◽  
Critical Diameter ◽  
Low Energy ◽  
Taper Angle ◽  
Energy Characteristics ◽  
Conical Form

The influence of the shape of donor charges on their initiating ability is investigated. The composition of these charges, based on chopped ammonium nitrate(V) and nitromethane in the ratio of 95-80% to 5-20%, was investigated experimentally. The composition has a detonation velocity of 3000-3300 m/s and a critical diameter of 5-9 mm. It is established that the use of the truncated conical form of donor charges with a truncated taper angle of 15°, 30°and 45°, contributes to the concentration of the detonation wave along its axis. The use in these charges of a composition based on ammonium nitrate(V) and nitromethane with low energy characteristics will increase the quality of blasting operations. For reasons of safety, it is proposed that mixing is carried out on-site.

Study on Detonation Features of Low Powder Detonating Fuse in the Bending Condition

2011 ◽  
Vol 243-249 ◽  
pp. 5960-5963
Author(s):  
Qun Mei ◽  
Jun Feng Zhu ◽  
Zuo Liang Li
Keyword(s):  
Numerical Simulation ◽  
Detonation Wave ◽  
Detonation Velocity ◽  
Small Angle ◽  
Normal Velocity

Detonation of low powder detonating fuse is studied in numerical simulation and experiments in bending conditions using LS_DYNA3D. The results show that pressure of the explosion and detonation velocity are decreased in the same section areas after bending. In bending conditions, detonation wave is similar to small angle corner diffraction. So the detonation velocity is lower than normal velocity.

Nucleic Acid Molecules Prepared by Monolayer Techniques

1972 ◽  
Vol 30 ◽  
pp. 178-179
Author(s):  
Dimitrij Lang
Keyword(s):  
Electron Microscopy ◽  
Standard Deviation ◽  
Nucleic Acid ◽  
Cytochrome C ◽  
Nucleic Acids ◽  
Contour Length ◽  
Sample Standard Deviation ◽  
Molecular Weights ◽  
Length Measurements ◽  
Protein Monolayer

The success of the protein monolayer technique for electron microscopy of individual DNA molecules is based on the prevention of aggregation and orientation of the molecules during drying on specimen grids. DNA adsorbs first to a surface-denatured, insoluble cytochrome c monolayer which is then transferred to grids, without major distortion, by touching. Fig. 1 shows three basic procedures which, modified or not, permit the study of various important properties of nucleic acids, either in concert with other methods or exclusively:1) Molecular weights relative to DNA standards as well as number distributions of molecular weights can be obtained from contour length measurements with a sample standard deviation between 1 and 4%.

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