Preliminary discussion on the ignition mechanism of exploding foil initiators igniting boron potassium nitrate

Exploding foil initiator(EFI)is a kind of advanced device for initiating explosives,but its function is unstable when it comes to directly igniting pyrotechnics.To solve the problem,this research aims to reveal the ignition mechanism of EFIs directly igniting pyrotechnics.An oscilloscope,a photon Doppler velocimetry,and a plasma spectrum measurement system were employed to obtain information of electric characteristics,impact pressure,and plasma temperature.The results of the electric characteristics and the impact pressure were inconsistent with ignition results.The only thing that the ignition success tests had in common was that their plasma all had a relatively long period of high-temperature duration(HTD).It eventually concludes that the ignition mechanism in this research is the microconvection heat transfer rather than the shock initiation,which differs from that of exploding foil initiators detonating explosives.Furthermore,the methods for evaluating the ignition success of semiconductor bridge initiators are not entirely applicable to the tests mentioned in this paper.The HTD is the critical parameter for judging the ignition success,and it is influenced by two factors:the late time discharge and the energy of the electric explosion.The longer time of the late time discharge and the more energy of the electric explosion,the easier it is to expand the HTD,which improves the probability of the ignition success.

A micro-chip exploding foil initiator based on printed circuit board technology

Conventional exploding foil initiator (EFI) in ignition or detonation applications hosts many performance advantages, but was hindered by the bulky, inaccurate, inefficient and expensive shortcomings. We highlight a novel micro-chip exploding foil initiator (McEFI) using printed circuit board (PCB) technology. The structural parameters were determined based on energy coupling relationship at the component interfaces. Next, the prototype McEFI has been batch-fabricated using PCB technology, with a monolithic structure of 7.0 mm (l) × 4.5 mm (w) × 4.0 mm (δ). As expected, this PCB-McEFI illustrated the successful firing validations for explosives pellets. This paper has addressed the cost problem in both military munitions and civil markets wherever reliable, insensitive and timing-dependent ignition or detonation are involved.

Piezoelectric responses of brittle rock mass containing quartz to static stress and exploding stress wave respectively

The electromagnetic emission(EME) induced from the rock containing piezoelectric materials was investigated under both static stress and exploding stress wave in the view of piezoelectric effect. The results show that the intensity of the EME induced from the rock under static stress increases with increasing stress level and loading rate; the relationship between the amplitude of the EME from the rock under different modes of stress wave and elastic parameters and propagation distance was presented. The intensity of the EME relates not only to the strength and elastic moduli of rock masses,but also to the initial damage of the rock. The intensity of EME induced by stress wave reaches the highest at the explosion-center and attenuates with the propagation distance. The intensity of EME increases with increasing the elastic modulus and decreases with increasing initial damage. The results are in good agreement with the experimental results.

Optimization Design of Exploding Foil Bridge Shape

The exploding foil,which is a main influence factor of exploding foil initiator(EFI),was studied to improve the utilization rate of energy in EFI.The burst currents of three bridge foils with different shapes were measured,and the sensitivity of initiation charge made of HNS-IV was tested by slappers.The test results show that,for O-shaped bridge foil,the burst current density is maximal,and the initiating voltage at 50% of firing probability of HNS-IV is minimal.The O-shaped bridge foil can be used to improve the utilization rate of energy in EFI and reduce the firing energy.

EXCITATION OF SPHERICAL SYMMETRIC EXPLODING WAVE WITH MOVING BOUNDARY

In this paper we have given an analytic excitation solution of exploding wave in infinite elastic body with growing spherical inner boundary, and the convergence region of series in this solution determined. Some characters of the displacement wave have also been discussed.

Expansion of Plasma of Electrically Exploding Single Copper Wire Under 4.5kA～9.5kA/Wire

The experimental system for electrically exploding single metal wire has been designed and manufactured. Expansion of the dense plasma column formed from an electrically exploding Cu wire of diameter 30 μm has been studied with a high-speed photographer to obtain the time-dependent radius (R-t) curve. The experimental results demonstrate that the mean expansion rate of the dense plasma column is 1.94 μm/ns, 2.6 μm/ns and 3.75 μm/ns according to the peak pulse current 4.5 kA, 7 kA and 9.5 kA respectively. The results can be beneficial to giving a profound understanding of the early stage of wire-array Z-pinch physics and to improvement on their design.

Preparation of Aluminum Nanoparticles by Exploding Wire in Different Liquids

The present work, provides a simple technique for the production of aluminum nanoparticles based on the explosion of thin aluminum wires in different liquids （distilled water, ethylene glycol and cyclohexane） by applying 36 Volte DC to two electrodes, one in the form of thin wire and the other in the form of plate and bring them to in touch mechanically. The nanoparticles are characterized by x-ray diffraction and UV-Visible spectroscopy. The x-ray diffraction results reveal that the nanoparticles continue to routine lattice periodicity at reduced particle sizes. The UV-Visible absorption spectrum of the liquid solution of the aluminum nanoparticles shows no characteristic Surface Plasmon Resonance （SPR） peak in the visible region. The TEM and SEM images show that the aluminum nanoparticles have narrow particle size distribution ranged from 20 to120 um with average particle size 80 nm. The aluminum nanoparticles prepared in water and that prepared in ethylene glycol show, no difference in their average particle size and distribution, while those prepared in cyclohexane show smaller sizes. It was observed that the particles have a little irregular shapes and low agglomerate was observed.

Migrated Exploding Reflectors in Evaluation of Finite Difference Solution for Inhomogeneous Seismic Models

Earth is inhomogeneous, which means its elastic characteristics change with depth. The seismic method employs the propagation of waves throughout the earth to locate different structures and stratigraphy. Understanding the wave propagation is an important matter in exploration seismology;therefore modeling of seismic wave is an important tool. To validate the interpreted earth model out of the seismic data, seismic synthetic seismograms should be generated in a process named “seismic forward modeling”. Finite difference method is used as one of the most common numerical modeling techniques. In this paper the accuracy of finite difference method in seismic section modeling is explored on different modeled data set of heterogeneous earth. It is shown that finite difference method completes with migration to reposition the events in their correct location. Two different migration methods are used and various velocities are also tested to determine an appropriate migration velocity. Finally the validly of finite difference modeling is examined using a 2D structural similarity index technique.

Enhancing Fire Safety in Commercial Vehicles: Assessing the Efficacy and Advantages of Exploding Fire Extinguishing Balls

Fire incidents in commercial vehicles pose significant risks to passengers, drivers, and cargo. Traditional fire extinguishing systems, while effective, may have limitations in terms of response time, coverage, and human intervention [1]. This study investigates the efficacy of a novel fire suppression technology—the Exploding Fire Extinguishing Ball (EFEB) —as an alternative and complementary fire safety solution for commercial vehicles. The research employs a multidisciplinary approach, encompassing engineering, materials science, fire safety, and human factors analysis. A systematic literature review establishes a comprehensive understanding of existing fire suppression technologies, including EFEBs. Subsequently, this study analyzes the unique features of EFEBs, such as automatic activation, as well as manual activation upon exposure to fire, and their potential to provide rapid, localized, and autonomous fire suppression. The study presents original experimental investigations to assess the performance and effectiveness of EFEBs in various fire scenarios representative of commercial vehicles. Experiments include controlled fires in confined spaces and dynamic simulations to emulate real-world fire incidents. Data on activation times, extinguishing capability, and coverage area are collected and analyzed to compare the efficacy of EFEBs with traditional fire extinguishing methods. Furthermore, this research shows the practical aspects of implementing EFEBs in commercial vehicles. A feasibility study examines the integration challenges, cost-benefit analysis, and potential regulatory implications. The study also addresses the impact of EFEBs on vehicle weight, stability, and overall safety. Human factors and user acceptance are crucial elements in adopting new safety technologies. Therefore, this research utilizes an experimental design to assess the performance and effectiveness of EFEBs in various fire scenarios representative of commercial vehicles. This dissertation presents original controlled experiments to emulate real-world fire incidents, including controlled fires in confined spaces and dynamic simulations. The experimental approach ensures rigorous evaluation and objective insights into EFEBs’ potential as an autonomous fire suppression system for commercial vehicles. This includes the perspectives of drivers, passengers, fleet operators, insurance agencies, and regulatory bodies. Factors influencing trust, perceived safety, and willingness to adopt EFEBs are analyzed to provide insights into the successful integration of this technology. The findings of this research will contribute to the knowledge of fire safety technology and expand the understanding of the applicability of EFEBs in commercial vehicles.

Characteristics of a plasma flow field produced by a metal array bridge foil explosion

To improve the energy utilization efficiency of metal bridge foil explosion, and increase the function range of plasmas, array bridge foil explosion experiments with different structures were performed. A Schlieren photographic measurement system with a double-pulse laser source was used to observe the flow field of a bridge foil explosion. The evolution laws of plasmas and shock waves generated by array bridge foil explosions of different structures were analyzed and compared. A multi-phase flow calculation model was established to simulate the electrical exploding process of a metal bridge foil. The plasma equation of state was determined by considering the effect of the changing number of particles and Coulomb interaction on the pressure and internal energy. The ionization degree of the plasma was calculated via the Saha-Eggert equation assuming conditions of local thermal equilibrium. The exploding process of array bridge foils was simulated, and the superposition processes of plasma beams were analyzed. The variation and distribution laws of the density, temperature, pressure, and other important parameters were obtained. The results show that the array bridge foil has a larger plasma jet diameter than the single bridge foil for an equal total area of the bridge foil. We also found that the temperature, pressure, and density of the plasma jet＇s center region sharply increase because of the superposition of plasma beams.

On the Estimates of Hyperbolic Area Distortion of Quasiconformal Mappings

The distortion property of hyperbolic area of planar quasiconformal mappings is studied in this paper. In the case of radial quasiconformal mappings and angular deformed quasiconformal mappings their hyperbolic area distortions are estimated quite sharply. The result can be applied to judge whether the hyperbolic area of a planar subset is explodable.

Electrothermal energy conversion mechanism of micro-scale semiconductor bridge

The response characteristics of resistance is observed by the analysis of experimental data of micro scale semiconductor bridge （MSCB） under different voltage inputs. Two critical voltages are found. One is called exploding voltage, above which the MSCB can be melted and vaporized without generating a plasma, and the other is called producing a plasma voltage, above which the MSCB is entirely vaporized, and then the current flows through the vapor producing the plasma. Based on the non Fourier heat conduction theory, the electrothermal energy conversion model is es tablished for the stage from heating to exploding, and then the correlation of MSCB and time is ob tained by graphic calculation. Importantly, the critical exploding voltage and exploding time are also derivate. With the comparison between the analytical result from the theoretical model and that from experimental data, it has been demonstrated that the theoretical model is reasonable and feasible for designing the exploding voltage and exploding time.

Effect of change of sand properties on travel distance of ricocheted debris

The debris from exploded buildings can ricochet after colliding with the ground,thus increasing the debris travel distance and danger from any associated impacts or collisions.To reduce this danger,the travel distance of ricocheted debris must be accurately predicted.This study analyzed the change in the travel distance of ricocheted concrete debris relative to changes in the properties of a sand medium.Direct shear tests were conducted to measure the change in internal friction angle as a function of temperature and water content of the sand.Finite element analysis(FEA)was then applied to these variables to predict the speed and angle of the debris after ricochet.The FEA results were compared with results of low-speed ricochet experiments,which employed variable temperature and water content.The travel distance of the debris was calculated using MATLAB,via trajectory equations considering the drag coefficient.As the internal friction angle decreased,the shear stress decreased,leading to deeper penetration of the debris into the sand.As the loss of kinetic energy increased,the velocity and travel distance of the ricocheted debris decreased.Changes in the ricochet velocity and travel distance of the debris,according to changes in the internal friction angle,indicated that the debris was affected by the environment.

Plasma Discharge Initiation of Explosives in Rock Blasting Application:A Case Study

A plasma discharge initiation system for the explosive volumetric combustion charge was designed, investigated and developed for practical application. Laboratory scale experiments were carried out before conducting the large scale field tests. The resultant explosions gave rise to less noise, insignificant seismic vibrations and good specific explosive consumption for rock blasting. Importantly, the technique was found to be safe and environmentally friendly.

On New Solutions of Classical Yang-Mills Equations with Cylindrical Sources

Strong fields generated by big electric currents are examined within the framework of the Yang-Mills nonlinear generalization of the Maxwell electrodynamics proposed in our earlier papers. First we consider the case of stationary currents and find a new exact solution to the Yang-Mills equations. Then we study a Yang-Mills field inside a thin circular cylinder with nonstationary plasma and find expressions for field strengths in it. Obtained results are applied to interpret several puzzling natural phenomena.

Similarity of Rayleigh-Taylor Instability Development on Scales from 1 mm to One Light Year

In this paper, we describe three different phenomena occurring on scales of 1 mm, 100 km, and almost a light year. The smallest scale is a laboratory experiment. The intermediate scale is a rocket-borne space experiment and the largest is an exploding star. In each case, deceleration creates a situation that is unstable to the Rayleigh-Taylor instability. The similarity exists in the spatial and in the Fourier domains;that is, not only are there obvious spatial similarities but the power spectra of the two phenomena are also nearly identical. The data compare favorably to published simulations.

Conductive Channel for Energy Transmission

Laser spark obtained by using a conical optics is much more appropriate to form conducting channels in atmosphere. Only two types of lasers are actively considered to be used in forming high-conductivity channels in atmosphere, controlled by laser spark： pulsed sub-microsecond gas and chemical lasers （CO2, DF （deuterium fluoride））, short pulse solid-state and UV （ultraviolet） lasers. Main advantage of short pulse lasers is their ability in forming of super long ionized channels with a characteristic diameter of- 100 mm in atmosphere along the beam propagation direction. At estimated electron densities below 1,016 cm3 in these filaments and laser wavelengths in the range of 0.5-1.0 mm, the plasma barely absorbs laser radiation. In this case, the length of the track composed of many filaments is determined by the laser intensity and may reach many kilometers at a femtosecond pulse energy of-100 mJ. However, these lasers could not be used to form high-conductivity long channels in atmosphere. The ohmic resistance of this type a conducting channels turned out to be very high, and the gas in the channels could not be strongly heated （〈 1 J）. An electric breakdown controlled by radiation of femtosecond solid-state laser was implemented in only at a length of 3 m with a voltage of 2 MV across the discharge gap （670 kV/m）. Not so long ago scientific group from P.N. Lebedev physical institute has improved that result, the discharge gap （-1m） had been broken under KrF laser irradiation when switching high-voltage （up to 390 kV/m） electric discharge by 100-ns UV pulses. Our previous result -16 m long conducting channel controlled by a laser spark at the voltage -3 MV was obtained more than 20 years ago in Russia and Japan by using pulsed CO2 laser with energy -0.5 kJ. An average electric field strength was 〈 190 kV/m. It is still too much for efficient applications.

基于PHP的成绩快速输入系统的设计

教师往往需要将学生完成作业的情况输入到电子表格中。但是,由于原始文档中存在多个班级,学生完成作业的顺序较为混乱,且数据量较大,直接输入费时费力。针对该问题,提出利用PHP设计成绩快速输入系统的解决思路。首先将学生的学号信息导入到MySQL数据库,然后通过PHP页面的文本框接收输入的学号字符串并自动增加新的作业字段,接着通过explode函数对字符串进行分割并提取学号,再根据学号与数据库对比更新当前作业所在字段,最后将数据表导出到电子表格。实践表明,该系统运行速度较快,稳定可靠,能够极大地提高工作效率。

Huge Star Explodes in Brightest Supernova Yet Seen

在浩瀚的宇宙空间,一颗比我们的太阳重150倍的恒星发生爆炸,结果是形成了一个超新星。令人稍感不安的是,爆炸点离我们的银河系和地球并不很遥远。

The Worn-out Power Battery Recycling Market About to Explode

Although a number of new energy automobile enterprises promise consumers that the battery’s service life and quality guarantee period may last about 10 years,the average life expectancy of power batteries is in fact more than 5 years if considering the usage environment and other factors.This means that the power battery recycling market is about to explode in 2018.