The ignition of a thin layer of explosive by impact

1974 ◽  
Vol 338 (1612) ◽  
pp. 77-93 ◽  
Keyword(s):  
Pressure Drop ◽  
Thin Layer ◽  
High Speed ◽  
Large Scale ◽  
Flow Speed ◽  
Thin Layers ◽  
Drop Weight ◽  
Flow Speeds ◽  
Show Evidence ◽  
Weight Impact

The behaviour of thin layers of solid materials under drop-weight impact is studied with the aid of high-speed photographic and pressure-measuring techniques. Photographic sequences taken with a high-speed framing camera show that explosive materials suffer large-scale deformation before initiation of explosion. The sample may undergo plastic flow in bulk, show evidence of partial fusion, and even (with PETN) melt completely. There is also evidence of Munroe jetting and instability of flow of material at the anvil/layer interfaces. The flow speed of the sample during these processes is considerable and may reach 300 m/s. When ignition of the layer occurs it does so at a small number of local hot spots, following which rapid combustion develops at speeds of 200-700 m/s. Strain-gauge measurements show that the pressures attained during drop-weight impact are typically 0.5-1 GPa (5–10 kbar) and the duration of impact 300–500 μs. In the course of impact of a thin layer of granular material a sharp pressure drop may occur, frequently from several hundred MPa down to zero. With an explosive layer, ignition occurs immediately following the instant of the pressure drop. The sudden fall in pressure is due to mechanical failure of the sample, and correlation of the two experiments shows that this is the cause of the very high flow speeds attained during impact. On the basis of these results a possible mechanism of ignition is suggested.

scholarly journals Modelling and pH Control in Raceway and Thin-Layer Photobioreactors for Wastewater Treatment

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1099
Author(s):  
María José Rodríguez-Torres ◽  
Ainoa Morillas-España ◽  
José Luis Guzmán ◽  
Francisco Gabriel Acién
Keyword(s):  
Wastewater Treatment ◽  
Thin Layer ◽  
Large Scale ◽  
Control Period ◽  
Ph Control ◽  
Thin Layers ◽  
Control Algorithms ◽  
Treatment Processes ◽  
Overall Performance ◽  
Reduction Of Co2

One of the most critical variables in microalgae-related processes is the pH; it directly determines the overall performance of the production system especially when coupling with wastewater treatment. In microalgae-related wastewater treatment processes, the adequacy of pH has a large impact on the microalgae/bacteria consortium already developing on these systems. For cost-saving reasons, the pH is usually controlled by classical On/Off control algorithms during the daytime period, typically with the dynamics of the system and disturbances not being considered in the design of the control system. This paper presents the modelling and pH control in open photobioreactors, both raceway and thin-layer, using advanced controllers. In both types of photobioreactors, a classic control was implemented and compared with a Proportional–Integral (PI) control, also the operation during only the daylight period and complete daily time was evaluated. Thus, three major variables already studied include (i) the type of reactors (thin-layers and raceways), (ii) the type of control algorithm (On/Off and PI), and (iii) the control period (during the daytime and throughout the daytime and nighttime). Results show that the pH was adequately controlled in both photobioreactors, although each type requires different control algorithms, the pH control being largely improved when using PI controllers, with the controllers allowing us to reduce the total costs of the process with the reduction of CO2 injections. Moreover, the control during the complete daily cycle (including night) not only not increases the amount of CO2 to be injected, otherwise reducing it, but also improves the overall performance of the production process. Optimal pH control systems here developed are highly useful to develop robust large-scale microalgae-related wastewater treatment processes.

scholarly journals Drop-weight impact ignition of CL-20 crystals caused by trapped gases: A high-speed photographic study

2020 ◽  
Vol 1 (2) ◽  
pp. 117-122
Author(s):  
Chuanguo Chai ◽  
Jianming Zhang ◽  
Shaojun Yu ◽  
Jinjiang Xu ◽  
Qian Yu ◽  
...  
Keyword(s):  
High Speed ◽  
Drop Weight ◽  
Trapped Gases ◽  
Weight Impact

High-speed photographic study of the drop-weight impact response of ultrafine and conventional PETN and RDX

2002 ◽  
Vol 130 (4) ◽  
pp. 298-306 ◽  
Author(s):  
J BALZER ◽  
J FIELD ◽  
M GIFFORD ◽  
W PROUD ◽  
S WALLEY
Keyword(s):  
High Speed ◽  
Impact Response ◽  
Drop Weight ◽  
Weight Impact

scholarly journals HIGH SPEED VIDEOMETRIC MONITORING OF ROCK BREAKAGE

2018 ◽  
Vol IV-2 ◽  
pp. 17-24
Author(s):  
J. Allemand ◽  
M. R. Shortis ◽  
M. K. Elmouttie
Keyword(s):  
High Speed ◽  
Impact Testing ◽  
Frame Rate ◽  
Sufficient Evidence ◽  
Video Frame ◽  
Rock Breakage ◽  
Impact Location ◽  
Drop Weight ◽  
Weight Impact ◽  
The Impact

Estimation of rock breakage characteristics plays an important role in optimising various industrial and mining processes used for rock comminution. Although little research has been undertaken into 3D photogrammetric measurement of the progeny kinematics, there is promising potential to improve the efficacy of rock breakage characterisation. In this study, the observation of progeny kinematics was conducted using a high speed, stereo videometric system based on laboratory experiments with a drop weight impact testing system. By manually tracking individual progeny through the captured video sequences, observed progeny coordinates can be used to determine 3D trajectories and velocities, supporting the idea that high speed video can be used for rock breakage characterisation purposes. An analysis of the results showed that the high speed videometric system successfully observed progeny trajectories and showed clear projection of the progeny away from the impact location. Velocities of the progeny could also be determined based on the trajectories and the video frame rate. These results were obtained despite the limitations of the photogrammetric system and experiment processes observed in this study. Accordingly there is sufficient evidence to conclude that high speed videometric systems are capable of observing progeny kinematics from drop weight impact tests. With further optimisation of the systems and processes used, there is potential for improving the efficacy of rock breakage characterisation from measurements with high speed videometric systems.

scholarly journals Solar-wind control of plasma sheet dynamics

2015 ◽  
Vol 33 (7) ◽  
pp. 845-855 ◽  
Author(s):  
M. Myllys ◽  
E. Kilpua ◽  
T. Pulkkinen
Keyword(s):  
Solar Wind ◽  
High Speed ◽  
Large Scale ◽  
Dynamic Pressure ◽  
Low Frequency ◽  
Time History ◽  
Solar Wind Plasma ◽  
Flow Speed ◽  
Occurrence Rate ◽  
Time Interval

Abstract. The purpose of this study is to quantify how solar-wind conditions affect the energy and plasma transport in the geomagnetic tail and its large-scale configuration. To identify the role of various effects, the magnetospheric data were sorted according to different solar-wind plasma and interplanetary magnetic field (IMF) parameters: speed, dynamic pressure, IMF north–south component, epsilon parameter, Auroral Electrojet (AE) index and IMF ultra low-frequency (ULF) fluctuation power. We study variations in the average flow speed pattern and the occurrence rate of fast flow bursts in the magnetotail during different solar-wind conditions using magnetospheric data from five Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission spacecraft and solar-wind data from NASA's OMNIWeb. The time interval covers the years from 2008 to 2011 during the deep solar minimum between cycles 23 and 24 and the relatively quiet rising phase of cycle 24. Hence, we investigate magnetospheric processes and solar-wind–magnetospheric coupling during a relatively quiet state of the magnetosphere. We show that the occurrence rate of the fast (|Vtail| > 100 km s−1) sunward flows varies under different solar-wind conditions more than the occurrence of the fast tailward flows. The occurrence frequency of the fast tailward flows does not change much with the solar-wind conditions. We also note that the sign of the IMF BZ has the most visible effect on the occurrence rate and pattern of the fast sunward flows. High-speed flow bursts are more common during the slow than fast solar-wind conditions.

scholarly journals Chromatographic Behaviour of Antibiotics on Thin Layers of Zeolite

2019 ◽  
pp. 1-8
Author(s):  
Adham Raeisi ◽  
Mostafa Ramezani ◽  
Hossein Ravazadeh ◽  
Mahdi A. Taher
Keyword(s):  
Thin Layer ◽  
Thin Layer Chromatography ◽  
High Speed ◽  
High Performance ◽  
Low Cost ◽  
Current Method ◽  
Thin Layers ◽  
Chromatographic Behaviour ◽  
First Time ◽  
Layer Chromatography

Introduction: Antibiotics analysis is performed by many methods such as spectrophotometry, fluorimetry, polarography, and high-performance liquid chromatography. This analysis doesn't require derivatization but requires expensive equipment and extensive preparation. When more than one antibiotic is present in a formulation, interactions may occur between the drugs that must be separated before measurement. Thin-layer chromatography is a useful technique for identifying antibiotics because of the low cost, high speed, and low servicing. Silica gel adsorbents have often been used as adsorbents in all thin-layer chromatography studies. In this study, zeolite was used as an adsorbent in thin- layer chromatography with high selectivity. Materials and Methods: The chromatographic behaviour of amoxicillin, ampicillin, cefazolin, cefixime, ceftriaxone, cefalexin, and penicillin was studied for the first time on a thin layer of zeolite with mobile, organic, and organic- organic phases. Discussion: The best separation of ceftriaxone from amoxicillin, ampicillin, cefazolin, cefixolin, cefalexin, and penicillin on a thin layer of zeolite using methanol as the mobile phase. The distance and rise time are 12 cm and 110 minutes, respectively. Conclusion: The results of the present study showed that using the current method, the selectivity of one antibiotic from other components as well as two-component andthree-component adsorption was obtained. Quantitative identification of antibiotics was also performed in multicomponent mixtures after selection of appropriate isolates.

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