The deflagration-to-detonation transition (DDT) model of the granular HMX was established based on the two-phase detonation model. The equation of state of the gas products was described by the calculated results of the CHEQ-like program which was based on the statistical mechanical theory. The DDT process of the granular HMX beds with an average grain size of 125 μm was numerical simulated by the CE/SE method. The effects of the loading density on the DDT was studied and compared with the experimental results. Numerical results indicate that the run distance to detonation has a U-shaped relation with the loading density.

The ruby pressure scale is revised using available static compression data of eleven markers at pressures up to 160 GPa, which includes Al, Cu, W, Au, Pt, Ta, Ag, Mo, Ni, Co, and Zn. The shock wave reduced isotherms of these markers are derived from shock Hugoniot and thermodynamic data using the same theoretical framework. These isotherms are then used to calibrate the ruby pressure scale, which shows good consistency based on simultaneous volume measurements. The calibration was processed by fitting all of these data to two ruby pressure scale forms, and gives the parameters A=1 923.4 GPa, B=9.75, and m=1 889.0 GPa, n=5.48, respectively. These two sets of ruby pressure scale differ by less than 2.1 GPa in the pressure range of 200 GPa. Making use of our ruby pressure scale in latter form, the static compression data of Au are reassessed. When the bulk modulus is fixed at 167 GPa, fitting the reassessed pressure-volume data to Vinet equation of state gives the first order pressure derivative of bulk modulus as 5.95, which has an excellent agreement with ultrasonic measurements.

The structural stability of Mn₃Zn_0.8Ni_0.2N was investigated up to 29.9 GPa by in situ angle dispersive X-ray diffraction using synchrotron radiation source and a diamond anvil cell. No structural phase transition was observed in the pressure range of 0-29.9 GPa. This result indicates that the changes in the physical properties of Mn₃Zn_0.8Ni_0.2N under pressure are not induced by structural phase transition. Through fitting the Birch-Murnaghan equation, we obtain the bulk modulus B₀=86.5 GPa for Mn₃Zn_0.8Ni_0.2N, assuming its first order derivative at ambient pressure.

With more and more frequently increasing of human's space activities, ejecta produced by micrometeoroid and small space debris impacting on spacecraft surface will also further affect the space debris environment. The ground experiments and numerical simulations about aluminum sphere projectile hypervelocity impacting on 5A06 aluminum plate were carried out in this work. The mean value of the special ejecta parameters, such as the mean velocity of ejecta, the mean size of ejecta, the mean ejected angle of ejecta, were studied, setting up a foundation for constructing the space debris environment model for ejecta. In this paper, multiple regression method was used to obtain the relation among the mean velocity of ejecta, the impact velocity, and the size of the projectile. The results show that SPH (Smoothed Particle Hydrodynamics) can be effectively used in numerically simulating the mean velocity of ejecta, the mean size of ejecta and the mean ejected angle of ejecta; the mean velocity of ejecta increases with the impact velocity, and the size of the projectile; the ejecta in the process of material ejection can obey cone shape approximately, and the mean ejected angle is nearly 41° but basically unaffected by the impact velocity and the size of the projectile.

Taking SiCl₄ as the precursor and the mixtures of hydrogen and oxygen as the explosion source, the influence on the product was investigated by changing the relative molecular mass of precursor. Through X-ray fluorescence (XRF), X-ray diffraction (XRD) and transmission electron microscopy (TEM), the structure, composition and size distribution of the detonation product were characterized and analyzed. The XRF characterization shows that the obtained product is mainly SiO₂ and this product purity is above 99.9%. The XRD characterization indicateds that the nano-SiO₂ powder belongs to the typical amorphous structure. The TEM images show that with the increasing of the relative molecular mass of precursor, the product were bonding gradually and its dispersion was reduced. The relative mole ratio of precursors should be controlled within 1.5.

According to the property that foreign materials can insert into graphite layers, nanometer graphite sheets with perfect performance can be prepared by detonation technique. This research, through establishing a finite element model of graphite intercalation compounds, obtained detonation parameters by fitting method, and revealed the functional relation between force and distance of the adjacent graphite interlayer with Thomas-Fermi equation. At last, the splitting process of adjacent graphite layer was simulated by LS-DYNA. Furthermore, the process of preparing graphite nanosheets by detonation technique was also described.

Differences in specific surface area and crystal structure between raw dietary fiber (DF) obtained from soybean and DF modified with dynamic high pressure microfluidization (DHPM) were analysis by nitrogen adsorption, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The results indicated that the specific surface area of DF was enlarged significantly (p<0.05) by DHPM treatment. The specific surface area of DF increased with the increase of pressure in the range of 40-140 MPa, and the maximum specific surface area of DF was 2.887 5 m²/g. When the pressure went on increasing, the accessibility to N₂ tended to decrease because of the aggregation of micro particles. XRD confirmed that both raw DF and modified DF had cellulose Ⅰ crystal structure. After DHPM treatment the crystal form of DF was not changed, whereas the apparent crystallinity of DF was reduced. The higher the pressure was, the less the apparent crystallinity was. FTIR spectra showed that DHPM led to 2-OH…O-6 intramolecular hydrogen bond and β glycosidic linkage decreased, and as the pressure increased the effect became more obvious.

The influence of defects on the dynamic performance of honeycomb is widely studied, but it is mainly focused on the effect of defect type and defect ratio, and the influence of defect distribution has not yet been fully developed. Effect of defect (the cell missing) distribution domain and its size on the in-plane dynamic impact properties of metal honeycomb was numerically investigated in this work based on explicit dynamic finite element simulation by ANSYS/LS-DYNA. Considering the deformation characteristics of perfect hexagonal honeycomb at different impact velocities, the specimen was divided into nine different sub-domains. Then, the influence of defect location, the size of single defect and the impact velocities on in-plane deformation modes and the energy absorption abilities of honeycomb were explored in detail. Results show that the in-plane dynamic impact properties of honeycomb depend on defect location as well as defect size. The dependence displays higher sensitivity especially at intermediate and lower impact velocities. With the increase of the impact velocity, the influence of defect location is weakened. Due to the existence of local defects, the in-plane energy absorption ability of honeycomb decreases obviously. However, comparing with the defect distribution, the absorbed energy per volume of honeycomb displays a higher sensitivity on the single defect size. The results potentially provide theoretical guides for the safety evaluation and energy absorption design of cellular materials.

First-principles density functional studies of the properties of zinc blende InN are presented. We have employed density functional theory, as implemented in the CASTEP code, to investigate the electronic, elastic and optical properties of the material zinc blende InN under hydrostatic pressure range up to 70 GPa. The optimized geometrical lattice constant of InN in the ground state obtained by using generalized gradient approximation is in good agreement with existing results and the lattice constants with pressure increasing. The calculated partial densities of states (PDOS) of the material have two regions in the valence band of InN. It is shown that the PDOS is quite low in the vicinity of the Fermi level, implying that it tends to form stable structure but has a poor conductivity. The elastic tensor components have linear scaling with pressure, C₁₁, C₁₂ and B have a positive scaling with pressure. Whereas C₄₄ and C_s have a negative scaling. The absorption spectra move towards the shorter wavelength direction. The shape of the spectra has almost no change when pressure increases. The results presented in this work is helpful for re-evaluating much of the pressure dependence of the properties for the material InN.

Electrical measurement under high pressure is an effective means to obtain physical property of materials. Using a microcircuit fabricated on a diamond anvil cell (DAC), we carried out the in-situ conductivity measurement on Fe₃O₄/β-CD at pressures. The electrical conductivity of the sample increases with pressure increasing to 39.9 GPa, experimental results indicate that Fe₃O₄/β-CD presents the transport behavior of a semiconductor. The abnormal conductivity changes at about 17.0 GPa is caused by the structural phase transition to high-pressure phase. The electrical conductivity indicates linear relation with pressure and can not return to original state，when the pressure comes back to ambient. As a result, we speculate high-pressure phase transition is not reversible.

Using laser scaners to measure the size of binary mixture of energetic materials thermite (Al+Fe₂O₃) and get the particle size distribution, the particle shape of aluminum powder, iron oxide and the contact status of the mixtures meeting the standard chemical proportion are observed under the electron microscope. Combined the raw material particle size distribution and the mass ratio of chemical reaction, the particle characteristic size (equivalent volume radius) and arrangement of aluminum and iron oxide particle were obtained. Based on the above conditions, the mesoscopic model for the thermite mixtures was established. The mesoscopic model can be guaranteed to get the statistical cavities structure consistent with that of the actual granular system. The features of “hot spot” for the thermite by impact were studied with the Smoothed Particle Hydrodynamics (SPH) method, under the condition of different particle arrangements and shock velocities. The result shows that the arrangement of three iron oxide particles closely contact each other is the basic one forming a single “hot spot”; the size of hot spot is determined by the initial size of the cavity; and the temperature of “hot spot” is controlled by the shock velocity. Finally, the thermite mixtures of different density and chemical ratio were impacted on the light gas gun, the qualitative regularities of experiments are well consistent with those of numerical simulation.

Total energy of BeP₂N₄ as a function of unit cell volume was calculated for phenakite and spinel-type structures using the density function theory (DFT). According to the Brich-Murnaghan's equation of state, the bulk modulus B₀ and for these two structures were obtained. The calculated results are all in good agreement with other theoretical data available in the literature, which indicate that BeP₂N₄ will transform from phenakite to spinel-type with increasing pressure. The results are in good agreement with experimental and other theoretical results. The energy gap slightly increases with pressure in the phenakite and spinel-type phases. The compression ratio of a/a₀ and V/V₀ were calculated. We find the the compression ratio of a/a₀ and V/V₀ of spinel structure BeP₂N₄ is the same that of diamond at lower 5 GPa. The B_H, G_H, B_H/G_H and E were also calculated at high pressure. By analyzing the changes of the total electronic density of states (TDOS) and the band gap under pressure, it is found that the energy band width and charge transfer for the two structures increase with increasing pressure. Moreover, the Be—N，P—N bond length is shortened and the electric charges are redistributed.

The interaction mechanism was analyzied between ejecta & micro-spalling and fiber-optic pins. The fiber-optic pins and pulsed in-line particles holography were applied in the diagnosis of ejecta and micro-spalling from shocked metal surface. The experimental results from fiber-optic pins are in agreement with those from pulsed in-line particles holography. In other words，the signals of fiber-optic pins illustrated the process of micron-scale fragments ejected from shocked metal surfaces. Due to the fact that fiber-optic pins have simple structures and the full-range of measurement from the zone of low areal density to the zone of thick metal sample, it is potentially effective in dectecting the phenomena of shocked metal surfaces.

Experiments were performed to investigate dissymmetry of Rayleigh-Taylor (R-T) instability of immiscible liquid initialized with a oblique initial interface. High pressure gas was used to accelerate a container filled with various liquid, the direction of acceleration from the lighter liquid to the heavy liquid, at the moment the interface is instability. The results of tilted angle 9° interfacial (ZnCl₂ solution/Hexane) evolution and mixing, were obtained from flow visualization experiments by the shadowgraph method. The obtained experimental result indicated that mixing ratio of TMZ is dissymmetry and the interfacial tilted angle is increased.

High-current pulsed electron beam (HCPEB) technique was used to irradiate the AISI 304L austenitic stainless steel. The vacancy defect clusters of the irradiated surface layer were investigated by using transmission electron microscopy. The experimental results indicated that a large number of supersaturation vacancies involving vacancy dislocation loops and stacking fault tetrahedra (SFT) were induced on the irradiated surface layer after HCPEB irradiation. Additionally, surface morphologies of the irradiated samples were characterized by optical microscope，scanning electron microscope and non-contact optical profiler in detail. It was found that high density, fine and dispersed micropores were inevitably formed. The dominating formation mechanism of surface micropores should be attributed to the migration of large number of vacancies (clusters) defect along line and (or) surface structure defects towards the irradiated near-surface layer during HCPEB bombardment and cause vacancies accumulation. The present results indicate that HCPEB technique is a new method to successfully fabricate the surface porous metallic materials by selecting appropriate materials and adjusting HCPEB process parameters.

Microorganism in food is one of the most important factors which cause food to decay. As one method of sterilization, ultra-high pressure has achieved significant effect in food manufactory. After a brief introduction to fundamental principle of ultra-high pressure sterilization technology, this review laid stress on the effects of high pressure on microbiological cellular configuration, metabolism, and hereditary mechanism. Finally, applications of ultra high pressure in food industry were prospected.

Using a cubic-anvil high pressure apparatus, Nylon 6 samples were annealed under different pressures. The crystallinity and crystal structure changes of Nylon 6 were studied by the methods of wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and infrared spectra. The results showed that the adjustment of nylon 6 molecular chains was suppressed because of the pressure loading, and the formation of the crystals was mainly realized by the reaction of transamidation.

In order to perform extensive research on the coaxial collision of elastic bar, finite element model was established based on LS-DYNA, the influences of the shape parameters of variable section bar on the stress wave were analyzed, producing mechanism of stress wave was discussed, and its application and development prospect in this field were also explored. The results show that, because of the variable section effect, the coaxial collision of variable section bar under conditions of some shape parameters can create the stress wave, which has the following characteristics: wave front rising is in the form of smooth concave curve, the rising time is longer and there is no waveform oscillations phenomenon. The characteristics are the intrinsic attributes of the coaxial collision of variable section bar, controlled mainly by minimum radius of variable section scope in bar, and length of variable section scope in bar exerts an influence on the partial difference; besides, the characteristics are not sensitive to the change of the loading speed. The laws obtained by the coaxial collision of variable section bar can be applied to many fields such as waveform shaping. Thus it can be seen, these laws extend the foundational theories, which can be of great theoretical and realistic significance, and moreover, its application prospect is wonderful.