With the development of techniques in the ultrafast physics experiment, there is an urgent need to fabricate a diagnostic equipment with a sufficiently high temporal and spatial resolution to study the characteristics of high energy products. As the resolution of the currently used ultra-high speed rotating mirror photography cannot meet the needs of the experiment, the ultra-high speed photo -electric camera has attracted increasingly greater attention due to its much higher resolution achieved. In our experiment the photo-electric and rotating mirror camera was used to investigate expanding fractures of the cylinder shell. The results show that the photo quality obtained by the photo-electric camera is greatly improved because this camera has a greater ability to eliminate motion blur during the experiment, and is capable of taking more photos. Thus we propose to use two cameras jointly so as to gain a better understanding of the physical process under investigation.

The total energy and enthalpy of bcc- and dhcp- Mo with different volumes were calculated using the generalized gradient approximation (GGA) within the framework of plane wave psudopotential density functional theory. Our calculated isotherms agree well with the previous results. Based on the comparison of enthalpy of bcc and dhcp structures, a bcc→dhcp structural transition was predicted. According to the results of phonon dispersions, the bcc phase may change into dhcp or 9R structures under high pressure. The calculations of mechanical stability also confirm that the dhcp structure is stable under pressures that are above 620 GPa. We also studied the thermodynamic properties of Mo such as Debye temperatures, isochoric heat capacity, and thermal expansion with the quasi-harmonic Debye model. Our calculated results show that the thermodynamic properties of bcc and dhcp structures do not differ significantly around 620 GPa.

In the present work, we investigated the crystal structure, electronic structure, optical properties and electrical properties of the wurtzite type ZnO oxide at exoteric pressures of 500 GPa based on the density functional theory ab-initio calculations framework. The results show that the lattice of ZnO is decreased at 500 GPa and, at the same time, the Zn—O bond length and the O—Zn—O bond angle are decreased while, however, the compressibility varies in different crystal directions and the symmetry remains the same. The band gap is direct at 500 GPa with the band gap value rising to 1.65 eV. The number of the energy bands decreases and so does the density of states. An obvious localization effect of the electrons is observed at 500 GPa. The absorption peaks move towards the high energy region, and the absorption decreases for low energy photon and increases for the high energy photon. The results from our analysis show that the density, effective mass and the mobility of the carriers near Fermi level decrease under 500 GPa, leading to a reduced performance of their electrical properties.

Based on the experimental results of a drop-weight impact test on reinforced concrete beams, the damage visco-elastic constitutive model has been proposed to describe the dynamic behavior of reinforced concrete. In view of the influence of the rebar and the damage characteristics of the beam, the reinforced multiplier and damage variable were introduced into the model to modify the constitutive model in such a way that it might be quantitatively described. Thus a constitutive model containing such control variables as strain, strain rate, damage and reinforcement ratio was obtained and then applied to the analysis of the fracture of the non-elastic bent beam. Numerical predictions were compared with the experimental deflection-time relationships, which shows a very good agreement with the experimental results.

The research on the expandable aimed warhead is expected to contribute a lot to the improvement of the damaging capability of the airborne missile due to the high efficiency of the warhead fragments' utilization. In this work we designed a prototype of this type of warhead based on its damaging mechanism and structural features, and put it to actual tests. The spreading process of the main charge was recorded with the high speed photography technology. The results show that this process matches with our numerical prediction, and the spreading time of the warhead was significantly shortened as the mass of the driving charge increases. Moreover, loading a greater quantity of charge in the external notch than in the internal one will benefit the synchronized spreading of all the main charge notches and also effectively facilitate the design of the detonation trigger system.

An inverse numerical method based on the characteristic curve was presented for better understanding of the mechanical behavior of materials under ramp loading.Numerical verification, uncertainties propagation and application of the inverse calculation were performed.From the measured velocity profiles of the stepped aluminum sample under the quasi-isentropic compression on the CQ-4 pulsed power facility, the wave propagation inside the sample was calculated using the inverse characteristic curve method and other methods.The calculated Lagrangian sound speed and the elastic limit of materials show that the inverse characteristic analysis can play a significant role in obtaining some key data of ramp loading experiments without having to rely on any constitutive model.

In the present study we fabricated Al/Steel composite by explosive expansion in order to obtain a composite pipe with both good mechanical properties and fine anticorrosion properties. In our fabrication a metal detonation cord with high a detonation velocity was used as the energy source, and the water was used as the pressure medium. The ultrasonic inspection of the fabricated product shows that the binding rate, the radial deformation rate and the bending percentage of the composite pipe are 100%, 0.65% and 0.12% respectively. The compression-shear and metallographic tests were also performed to characterize the composite pipe, and the results are as follows: the bonding strength is 3.27 MPa, higher than the officially required minimum value in the construction industry and the petrochemical industry. In addition, the bonding interface is flat and smooth, without evidence of any partial over-melting occurring, and the inter-diffusion between Al and steel is found to have occurred.

In our study the performance of projectiles' oblique penetration into concrete was investigated. Based on target and projectile separation, the decay function was constructed with the free-surface effect taken into consideration, and the semi-empirical resistance function was obtained, thus replacing the boundary condition of the target with this decay function.In our simulation and experiment, the deflection angle and the acceleration of the projectile were calculated and, in addition, the relationship between the penetration depth, the oblique angle of the target, and the velocity of the projectile was obtained.The simulation results are in good agreement with the experimental results, which further confirms the reliability of the present theory.

Thin-walled structures have been widely used in engineering practice, and great attention has been paid to the study of local changes that occur in their material properties and thermal stress as they have a great influence on the structures' bearing capacity.In our study, the laser power density, irradiation spot radius and thickness of the sheet were first taken into consideration in the analysis of the thermal nonlinear buckling behavior of the thin-walled structures under local irradiation.Then, the arc-length method was applied in the investigation of the stability of the thin-walled structures under combined external loads of axial compression and laser irradiation.Our numerical results indicated that the buckling capability of the thin-walled structures decreases almost linearly with the increase of irradiation time and irradiation spot radius, but increases exponentially along with the increase of sheet thickness.

In this work we carried out an experiment to investigate the effects of positive high-voltage electric fields on the flame propagation and combustion characteristics of lean premixed CH₄/O₂/N₂ flames in a constant-volume combustion chamber when the excess air ratio is respectively 1.6 and 1.8.The results from our experiment show that the flame propagation is significantly improved in the field direction with the application of positive DC electric fields, and this phenomenon is increasingly more obvious with the increase of the electric field.When the voltage input reaches 12 kV, the mean flame propagation velocities for λ=1.6 and 1.8 are 1.38 and 1.07 m/s, respectively, which is an increase by 133.41% and 369.97% compared to the case without an electric field.Moreover, at U=12 kV, the peak pressures for λ=1.6 and 1.8 are increased by 13.07% and 100.81%, and the corresponding time it takes for the peak pressure to occur is advanced by 35.94% and 18.09% respectively.It is therefore concluded that the combustion of lean premixed CH₄/O₂/N₂ can be significantly improved by the positive high-voltage electric fields applied.

The influence of the input voltage, size of the exploding foil, and the covering material on the exploding characteristics of the micro-size exploding foil were investigated by our experiment.The results show that the exploding time span is mainly determined by the input voltage and the cross section of the exploding foil and, in addition, neither the length nor the covering material of the exploding foil have any significant effect on its exploding characteristics.The exploding time span tends to get shorter with the increasing of the input voltage and the decreasing of the cross section area.Besides, the threshold curves of the electric-explosion of the micro-copper foil with certain circuit parameters are obtained from the experiment, which can provide valuable information on the optimization of the design of the micro-exploding foil.

Compared with the conventional rock breaking by high pressure water jet, the energy efficiency can be greatly improved by adding steel shots into the water jet.The transient nonlinear dynamics finite element simulation software was used to analyze the rock breaking process by steel shots, which was further verified by the results of indoor experiments.The rock breaking process can be divided into three stages:at the beginning the penetration depth increased fast from 0 to 20 s, then the invasion speed decreased gradually from 20 to 80 s, and finally, the penetration depth remained unchanged after it reached 80 s.In addition, it is not a proportional relationship between the rock breaking volume and the steel shot concentration due to the steel shots' intervention. The experimental results can be summarized as follows:When the steel shot concentration is 0.5%~3.0%, the rock breaking volume increases remarkably with the increase of the steel shot concentration.However, when the concentration exceeds 3.0%, the rock breaking volume is almost unchanged as the steel shot concentration increases.

Allyl isothiocyanate (AITC), a reaction product of glycosidase hydrolyzing glucosinolates in the extracts of purple cabbage pigment, causes an unpleasant odor in the purple cabbage pigment, which limits its application in food industry.We investigated the technology for removing AITC by HPCD (High Pressure Carbon Dioxide) treatment, and the removing effects under 5 different conditions of pressure, temperature, treatment time and pressure relief time, respectively.We optimized the technological parameters by single factor experiment and orthogonal experiment.The optimized technological parameters of HPCD treatment are 50 ℃ for temperature, 60 min for treatment time, 2 min for pressure relief time.After the optimum HPCD treatment, the number of unpleasant-odored food compounds decreased from 17 to 7, with many odorous impurities removed to different degrees, and the core odorous impurity AITC in purple cabbage pigment was reduced from 3.15% to 1.06%, thus achieving a good odor-removing effect.