Modeling the blast load induced by a close-in explosion considering cylindrical charge parameters

Structural damage is significantly influenced by the various parameters of a close-in explosion.To establish a close-in blast loading model for cylindrical charges according to these parameters,a series of field experiments and a systematic numerical analysis were conducted.A high-fidelity finite element model developed using AUTODYN was first validated using blast data collected from field tests conducted in this and previous studies.A quantitative analysis was then performed to determine the influence of the charge shape,aspect ratio(length to diameter),orientation,and detonation configuration on the characteristics and distributions of the blast loading(incident peak overpressure and impulse)according to scaled distance.The results revealed that the secondary peak overpressure generated by a cylindrical charge was mainly distributed along the axial direction and was smaller than the overpressure generated by an equivalent spherical charge.The effects of charge shape on the blast loading at 45°and 67.5°in the axial plane could be neglected at scaled distances greater than 2 m/kg^(1/3);the effect of aspect ratios greater than 2 on the peak overpressure in the 90°(radial)direction could be neglected at all scaled distances;and double-end detonation increased the radial blast loading by up to 60%compared to singleend detonation.Finally,an empirical cylindrical charge blast loading model was developed considering the influences of charge aspect ratio,orientation,and detonation configuration.The results obtained in this study can serve as a reference for the design of blast tests using cylindrical charges and aid engineers in the design of blast-resistant structures.

Numerical Simulation of Innovative Operation of Blast Furnace Based on Multi-Fluid Model

A multi-fluid blast furnace model was simply introduced and was used to simulate several innovative ironmaking operations. The simulation results show that injecting hydrogen bearing materials, especially injecting natural gas and plastics, the hydrogen reduction is enhanced, and the furnace performance is improved simultaneously. Total heat input shows obvious decrease due to the decrease of heat consumption in direct reduction, solution loss and silicon transfer reactions. If carbon composite agglomerates are charged into the furnace, the temperature of thermal reserve zone will obviously decrease, and the reduction of iron-bearing burden materials will be retarded. However, the efficiency of blast furnace is improved just due to the decrease in heat requirements for solution loss, sinter reduction, and silicon transfer reactions, and less heat loss through top gas and furnace wall. Finally, the model is used to investigate the performance of blast furnace under the condition of top gas recycling together with plastics injection, cold oxygen blasting and carbon composite agglomerate charging. The lower furnace temperature, extremely accelerated reduction rate, drastically decreased CO2 emission and remarkably enhanced heat efficiency were obtained by using the innovative operations, and the blast furnace operation with superhigh efficiency can be realized.

Benchmark calculations and error cancelations for bond dissociation enthalpies of X-NO_(2)

Safety plays an important role in determining the applicability of energetic compounds,and the bond dissociation enthalpy(BDE)of the“trigger bond”X-NO_(2) provides useful information to evaluate various safety properties.Accurate and rapid calculation of the BDE of X-NO_(2) is of great significance to perform the high-throughput design of energetic compounds,which becomes an increasingly popular means of materials design.We conduct a benchmark BDE calculation for 44 X-NO_(2) samples extracted from the iBond database,with the accuracies of 55 quantum chemistry calculation levels evaluated by the experimentally measured values.Only four levels have the global mean-absolute deviation(MAD)less than 10 kJ/mol,but no calculation level can achieve that all the local MADs of each category less than 10 kJ/mol.We propose a simple correction strategy for the original calculation deviations,and apply it to 30 calculation levels screened out through a series of accuracy assessments and obtain the corrected MAD<6 kJ/mol in some cases.We define a normalized time-cost(NTC)to evaluate the time-cost of each calculation level,and confirm that PBE0-D3/6-31G^(**)(MAD=6.4 kJ/mol,NTC?0.8)works the best for most cases,followed by M062X/6-31g^(**),M062X/6-311g^(**)andɷB97XD/6-311g^(**),based on an insight into the accuracy-cost trade.The present work provides an accurate and fast solution for calculating XNO_(2) BDE via quantum chemical methods,and is expected to be beneficial to enhance the safety prediction efficiency of energetic compounds.

STUDY ON THE ON－LINE OPTIMAL CONTROL OF PARAMETERS OF THREE－CONE BLAST HOLE DRILLS

A model recognition method for the on-line optimal control of the parameters ofthree-cone blast drills is developed. It takes a few of on-line measurements and has a rapidoptimization speed. The mathematic model for on-line optimal control of the parameters and thedetermination of the parameters in the model are also presented.