When analyzing the penetration of a rod-shaped projectile in semi-infinite target, the velocity gradient of the shaped charge jet is taken into account. The jet is divided into a series of segments, and the variations of the length and diameter of each jet segment are calculated at the moment of impacting on the target. Through the Bernoulli equation, linear approximations of velocity and diameter of the jet, and static method, the relationship between penetration depth and hole diameter in the target and impacting jet is obtained. Moreover, the simulated results are in quite good agreement with the experimental data.

After metal jets penetrate the steel target, the jets' material adheres on the penetration channel wall. The research on the jets' material is helpful to analyzing the dynamic superplastic deformation and morphological changes of jets in the process of penetration and cooling. Theoretical computation and numerical simulation are used in this work to study the penetration process of copper jets, and the changes of temperature and grain size of copper jets adhered on the penetration channel wall are obtained. The simulated results are in good agreement with the SEM (Scanning Electron Microscope) observation. From the observation of microstructure of copper and steel, we can get the conclusion that the copper jets do not melt but instead undergo dynamic recrystallization in the process of penetration. In addition, the copper grain size increases obviously and the twins are formed in the cooling process.

Laser-driven plasma jets provide a new way to simulate astrophysical jets and generate shockless loading in solids to high pressures, which are very important in the researches of high energy density physics. The experiments are all under the conditions with very high laser intensity in literatures, but there is no criterion of the basic condition under which the plasma jets can form from the rear surface of the driven film. The main objective of the current study is to investigate the effects of laser intensity, wavelength, pulse width, target material, and target thickness on plasma jet using analytic numerical methods. The results show that the shock strength before exiting the rear of the reservoir must be higher than a threshold value for jet formation. For polyethylene, this value is about 80 GPa. The lower wavelength, boiling temperature, and ionization threshold value, and higher laser intensity, longer pulse width, thinner target, the plasma jet is more easily achieved for the thin target with low boiling temperature and small ionization threshold value when irradiated by a pulsed laser with high intensity, short wavelength and long pulse width.

Motivated by the current interest in the mechanism of the deflagration to detonation transition (DDT), the DDT experiments of epoxypropane-air mixture and epoxypropane-aluminum-air mixture are carried out by a large-scale tube (32.4 m long and 0.199 inner diameter). The processes of DDT in multi-phase clouds are analyzed, and the mixtures with different concentrations are compared. The self-sustained detonation waves are formed in the epoxypropane-air mixture with epoxypropane concentration of 513 g/m³ and epoxypropane-aluminum-air mixture with epoxypropane and aluminum concentrations of 237 and 643 g/m³, and moreover the cell size of the detonation are 0.28 and 0.5 m, respectively.

Based on the C-J theory and polytropic gas equation of state, a simple physical model is developed to calculate the parameters of overdriven detonation wave for C₂H₂-O₂ mixture with a stoichiometric ratio. The overdriven detonation experiments are also performed in a shock tube using a high speed digital camera and six piezoelectric sensors. The calculated overdriven detonation velocity is in agreement with the experimental value. Therefore, the overdriven detonation parameters obtained by this method are feasible and effective.

Numerical simulation is first conducted herein of the perforation of reinforced concrete slabs by an ogival-nosed projectile using LS-DYNA. The triaxial test data reported in this paper for the 48 MPa concrete are used to determine the values of the parameters employed in the Holmquist-Johnson-Cook (HJC) model. It is shown that the numerical simulations correlate well with the experimental observations in terms of ballistic limit, residual velocity, impact crater, penetration tunnel and scabbing crater. The response of reinforced concrete slabs to explosive loading is also studied numerically by the fluid-solid coupled method of LS-DYNA. The simulation reproduces the transient process of the shock wave and the main rupture process of the slabs. The numerically obtained pressure-time histories are found to be in reasonable agreement with those predicted by the empirical equations; the failure patterns obtained by the numerical simulation are found to be similar to those obtained experimentally.

Two mutant cucumber lines are obtained from the Tianjin cucumber cultivar S9925-3 after treatment with high hydrostatic pressure. DNA fingerprint analyses are performed for the two mutants and their parental wild-type cucumber cultivars by AFLP (Amplified Fragments Length Polymorphism) analysis. A total of 30 randomly selected primer pairs are used for AFLP. Ten specific different bands between the mutants and the wild-type cucumber cultivars are excised from the polyacrylamide gel for DNA sequencing. Alignment of the obtained DNA sequences with NCBI (National Center for Biotechnology Information) database identifies the mutation sites in cucumber genome, which may be the reason of phenotypic changes of the mutant cucumbers. This is the first time that a study has showed at molecular level that treatment with high hydrostatic pressure results in stable mutations in cucumber cultivar. Our results indicate that high hydrostatic pressure-induced mutational breeding can be used as an effective approach for the crop improvement.

The numerical simulations were performed to study the standing detonation wave structure and performance induced by a supersonic inflow impinging on a cone. The variations of detonation wave structure and the pressure behind the wave at the different initial temperatures of inflow were analyzed. The results show that the ratio of pressure increase is enhanced along with the decrease of the initial inflow temperature, which is benefit from the improvement of propulsion performance of oblique detonation wave engine. At the higher initial inflow temperature, the detonation wave front shows a smooth shape, while at the lower initial temperature, the triple structures appear at the front. The lower initial temperature is, the more number of the serried triple points are. These triple points with higher pressure contribute to the pressure variations behind the standing detonation wave.

The polycrystalline diamond compact (PDC) samples sintered at 1 460 ℃, 5.6 GPa and at varied sintering time were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and EDX. In the XRD patterns, graphite (002) peak was found in the sample sintered for 40 s. It was also found that the WC (100) peaks in different samples change from weak to strong and then to weak, and finally disappear with the increase of the sinter time of PDC. Furthermore, the calculated results from the XRD data show that the magnitude of the cell parameter of the cobalt in the diamond layer of PDC increases with the sinter time due to the solution of the W or C. It was observed that the distribution of the cobalt diffusing from the substrate of WC is uneven.

To investigate the dynamic friction behaviors of rock interface, series of experiments including oblique planar impact with inclination angle 20° and 30°, impact loading velocity ranging from 42.2 m/s to 130.6 m/s for Fangshan granite, are carried out. Experiments with inclination angle 20° were carried out to study interfacial properties for specimen without interfacial sliding, and those with inclination angle 30° were used to study the dynamic friction behaviors for specimens with interfacial sliding. Experimental results preliminarily revealed the dynamic friction behaviors of granite surface under the pressures range from 317 MPa to 685 MPa and the surface sliding velocities range from 2.76 m/s to 24.88 m/s. The preliminary results indicated a complicated process of the dynamic friction, which is helpful for the understanding of the earthquake slip.