The electrons structure and photoelectric properties of zinc-blende structural ZnTe were investigated under high pressure, using first-principles plane-wave pseudo-potential method.The dielectric function and optical absorption coefficient were also predicted under high pressure.The results show that the distributions of density of states of Te and Zn atoms under high pressure shift towards lower energy direction and cover wider range.High pressure leads to stronger hybridization between Te 5p and Zn 3d electrons.The direct band gap increases gradually with pressure while the indirect band gap decreases.The direct band gap structure becomes an indirect one when the ambient pressure reaches 10.7 GPa.High pressure helps the transitions between Te 5p and Zn 3d electrons.The optical absorption coefficient increases, which leads to more electron-hole pairs and enhances the conductivity.

Using a 24 mm bore two-stage light gas gun, plate impact experiments were performed on unsaturated clay at 3 moisture contents-0, 8% and 15%-to obtain its Hugoniot data.The shock wave motions in the samples were detected by fiber-optic pins, and the pressure in the sample ranged from 1.29 to 32.54 GPa.The experiment results indicate that the moisture content has a significant effect on the shock compression properties of unsaturated clay.While compressed, the gas and water in pores cannot escape promptly due to the transient loading time, thus they dominate the shock compression properties of unsaturated clay together with the solid grains.Since water is much stiffer than gas, the compressibility of unsaturated clay decreases as the moisture content increases.Besides, a modified three-phase equation of state is introduced to describe the pressure-density relationship of the unsaturated clay, which shows good agreement with the experimental data.

In the process of projectile explosive driving, the front surface of the projectile whose thickness is larger than a certain size is usually packaged to reduce the negative pressure and prevent spalling.It is found that two negative pressures may be produced in the packaged projectile under the explosive load pulse.The first negative pressure is only relevant to the type of the package material, in addition to which, the second negative pressure also depends on the thickness of package material.With the given projectile and package material, the critical condition satisfied by loading pressure of shock wave and unloading pressure of rarefaction wave is derived.The first negative pressure is prevented under this condition.Furthermore, when the value of the first negative pressure is zero, in order to prevent the second negative pressure, the critical thickness of the package material is obtained in this paper.The projectile Fe, Al packaged by different materials are simulated by AUTODYN simulator and the analytical results are in good agreement with those of numerical results.Besides, the contrast of rectangular and triangular shock wave is given.This work will provide reference for engineering design of the package materials in the process of projectile explosive driving.

In order to understand the characteristics of acoustic emission signals caused by hypervelocity space debris impacting spacecraft with shields, a two-stage light gas gun was used to launch sphere projectiles to impact an aluminum-alloy Whipple shield, the induced acoustic emission signals were acquired, and analyzed by wavelet packet technology and energy entropy theory.The experimental results indicate that, the initial velocity of projectile, bumper thickness and projectile diameter are important factors to decide the form of debris cloud and characteristics of acoustic emission signals.The wavelet packet energy entropy could be used to describe the frequency complexity of debris cloud impact signals.When the initial velocity of projectile increases in the broken section (3-7 km/s), along with which the projectile breaks more completely and the energy entropy of acoustic emission signals increases.Under the experimental conditions, the bumper thickness has greater influence on energy entropy values than the projectile diameter.The wavelet packet energy entropy is helpful to estimate the initial velocity of projectile and the maximum impact damage region, combined with the predicted curve from the Christiansen ballistic limit equation, the damage pattern recognition of the bulkhead could be assessed.

Liquid fuel and RDX dust were dispersed at the same time in a detonation tube with an inner diameter of 200 mm and length of 5.4 m, and the cloud formed was initiated by high explosive from the bottom.Detonation pressure and velocity were obtained by the pressure measurement system, and photos and detonation cell were got by smoke trace technology.The results indicate that the 90^# solvent oil-air cloud detonation pressure is 5-6 MPa, which means the 90^# solvent oil can be used as a main fuel of fuel-air explosive.By adding isopropyl nitrate (IPN), its critical initiation energy can be lowered, and by adding RDX the detonation pressure and velocity can be raised.The calculation and experimental verification also found a link between the critical initiation energy and detonation cell size of multi-phase detonation which is similar with the gaseous detonation.

As a promising candidate material in explosive power supplies, the porous PZT95/5 ferroelectric ceramics exhibit attractive advantages in engineering applications.However, the electrical breakdown of ferroelectric ceramics usually reduces their discharge efficiency, and even results in failure of the explosive power supply.In this paper, we presented a theoretical model of electro-mechanical breakdown for the porous PZT95/5 ferroelectric ceramics in quasi-static electric fields.The model is based on the mechanism of electro-mechanical breakdown and partial discharges in conducting channels generated inside the ceramics.Theoretical predictions of the critical electric-field breakdown strength of the ferroelectric ceramics with different porosities are carried out, and show good agreements with the experimental results.The characteristic size of the conducting channel increases with the porosity, which causes a significant reduce in the critical electric-field breakdown strength.

Based on the principle of massive support, the parameters of ultra-high pressure tungsten carbide (WC) anvil have been stuied by finite element method.The results indicate that the technologies of radius beveling and concave region can enhance the performence of ultra-high pressure WC anvil, by decreasing the focus phenomenon of stress and increasing the lateral support, respectively.Further more, the pressure transmission efficiency of new anvil is higher compared with the traditional anvil, which can be enhanced about 58.5%.The rate of cracking in new anvil decreases about 33% than that of traditional anvil.The highest sample cell pressure generation by new anvil increases about 44.2% compared with the traditional anvil, which changes from 6.63 GPa to 9.56 GPa.This work represents a new structure of ultra-high pressure WC anvil for study on the novel structure and properties of matter, design and synthesis of functional materials.

The purpose of this study is to investigate the effects of deformation-induced defects on optical transparency of MgO single crystal under shock loading.With the nanosecond-time-resolved 40-wavelength radiation pyrometer and shock-compressed in situ light source techniques, transmission spectrums of single crystal MgO shocked along 〈100〉 direction on two-stage gus gun were measured. Spectrums of the measurements ranged from 400 to 800 nm.Curves of absorption coefficients versus wavelengths under ≈50 GPa and ≈70 GPa were obtained.Color center absorption peaks (410, 460, 490, 580 nm assigned to aggregate F type centers; 520 nm to V^- center; 660 nm probably to absorption related with interstitial atom) indicate point defects created during shock plastic deformation process.It is for the first time that color centers of point defects were observed in real time.

We adopted a new version of ghost fluid method (NGFM) to treat the wall boundary in a complex calculation region in Cartesian coordinate system, and real ghost fluid method (RGFM) to predict the flow states at grid nodes just next to the gas-liquid interface.Flow field was solved by Euler equation with 5th-order WENO spatial discretization and 2nd-order Runge-Kutta (R-K) time discretization.We used the level set method to keep track of gas-liquid interface.Level set function was discretized by 5th-order Hamilton-Jacobi WENO and 3rd-order R-K method.We verified that NGFM was easy to extend and could be applied to treat complex wall boundary in Cartesian grid by comparing with results in arbitrary coordinate system.We carried out pressure contours, the change process of bubble shape and pressure history at some given points.The numerical results demonstrate that the expansion of high pressure bubble is restricted by the reflected shock wave from the wall.It is also shown that the reflection of strong shock wave from wall can lead to extensive cavitation flow.

The technique of magnetically driven isentropic compression has many advantages over previous experimental techniques of quasi-isentropic compression, such as the smoothly increasing pressure loading to a high magnitude without any initial shocks, the ability to investigate several samples under identical loading conditions in one shot, high benefit-cost ratio, etc.The main parameters of CQ-1.5 rebuilt by Institute of Fluid Physics, CAEP, are detailed.This apparatus aims at isentropic compression and driving high-speed flyers, its designed maximum pressure is 50 GPa.The samples of 45 steel are isentropically compressed by CQ-1.5 to a pressure as high as 47.5 GPa without any appearance of shock, a Doppler pins system (DPS) is used to record the velocity history of flyers.We use a backward integration method to treat the experimental data, and obtain thep-V relation of 45 steel under quasi-isentropic compression.We also ascertain the parameters of 3 forms of isentropic equation of 45 steel.The maximum isentropic pressure in this work is 47.5 GPa.

Combining the simulation with the experimental results of the penetration process of penetrator with enhanced lateral effect (PELE) in metallic target, the process of the shell expansion can be divided into two stages, the accelerating expansion and the uniform expansion.Based on the model of the damage function by Feng Jiabo, we obtained the damage and fracture evolution equation responsible for the shell of PELE.According to the damage evolution equation responsible for the shell of PELE, the fracture process parameters of PELE were calculated.Moreover, the relationship between shell fracture critical strain and velocity of the projectile was analysised, which is useful in engineering design of PELE.

Stress wave propagation in the constrained explosive under shock loading was studied through simulation for the needs of both housing explosive stability in high-speed missiles and the security of weapons during accidents.The resistance forces of both missiles and housing explosive during the progress of penetration were calculated with different penetration velocities.A high-precision and low-dissipation spectral-element method was used to simulate the stress wave propagation in explosives under shock loading for the first time.The temperature rise caused by friction on the charge-shell interface was calculated with consideration of the friction property, and the plastic energy was also computed.The spectral-element method is successfully applied in the simulation of the stress wave propagation in constrained explosive, and the results can provide a reference to the analysis of housing explosive.

Deformation of perforated plates under impulsive loading of blast wave was simulated by AUTODYN software and the deflection relationship of plates with different hole numbers and diameters was obtained.Experiments were designed and the consistency between model computation and experiment results was validated.A general perforated plate deflection formula was proposed based on deflection formula of non-hole thin plate and the computation results, which can provide reference for damage estimation of perforated plate and damage study on effects of fragment and blast wave.

A monodisperse model was introduced to simulate the TiO₂ nanoparticles synthesization during the gas phase explosion.The calculation of this model was based on the experimental results and CJ theory which describes the gas phase explosion field.After a numerical analysis and theoretical explanation, the model was validated in comparison with the experimental results of gas phase explosion synthesis of TiO₂.TiO₂ nanoparticles with diameter of 20-150 nm were obtained.The results show that the numerical analysis can give a rapid predictive result of TiO₂ nanoparticles synthesis, and the main factors affecting the growth of nanoparticles are reaction temperature, concentration of particles and reaction time.

Thermo denatured rice protein was treated by 100 MPa for 10 min at 25 ℃ and then was hydrolyzed with Alcalase.The solubility and structural characterization of the protein and its hydrolysates were analyzed by size exclusion-high performance liquid chromatography (SE-HPLC), Fourier transform infrared spectroscopy (FTIR) and scanning electric microscope (SEM) so as to evaluate the effect of high pressure.The results showed that the solubility of hydrolyzed rice protein after high pressure treated could elevate to 75.33% from 58.9% of non-high pressure treated.The 57-105 ku fraction of the protein showed a dissolved state after high pressure treatment, and the contents of 4.4 and 2.0 ku fractions increased during the hydrolysis of the protein, which were different from that of non-high pressure treated.The β-sheet and β-turn were the major conformation of the protein.The structure of the protein body particles became loosen and easier to be hydrolyzed after high pressure treatment.These results show that 100 MPa treatment could promote the enzymatic hydrolysis of thermo-denatured rice protein.

Waxy maize and tapioca starch with different starch-water ratios were treated by high hydrostatic pressure (HHP)-a physical modification method-under 600 MPa.The effects of moisture content on gelatinization and retrogradation properties of the two kinds of starch were investigated.The appearance and particle size of granules were studied by micro-polariscopy, scanning electron microscopy and laser diffraction instrument.Combining the X-ray diffraction and nuclear magnetic resonance (NMR) spectrum, the change from crystal to non-crystal was confirmed again, and the water status in starch was studied, too.The results indicate that the crystalline structure destroying and gelatinization happen when the starch-water ratio was between 3/10 and 5/10.The degree of retrogradation for waxy maize starch was 4/10 > 3/10 > 5/10 (starch-water ratio), whereas the degree of crystalline structure destroying for tapioca starch was 3/10 > 4/10 > 5/10 (starch-water ratio).The diameter of waxy maize and tapioca starch granules increased significantly with moisture content.Water was kept within the crystalline lamella in the form of bond water.

The inactivation of pectin methylesterase (PME) from peach in buffer and juice by high pressure carbon dioxide (HPCD) was investigated.PME in buffer is effectively inactivated by HPCD, their residual activity decreases with the increase of pressure and temperature.The residual activity of the PME exhibited a fast decrease after a prolonged treatment time; their inactivation kinetics is adequately modeled by the first order kinetics model.With the increase of pressure and temperature, the kinetic rate constant increases and the decimal reduction time decreases for PME in buffer inactivated by HPCD.The Kinetic rate and the decimal reduction time are 0.408 8 min^-1 and 5.63 min respectively at the optimal condition (22 MPa, 55 ℃).The activation volume and the pressure sensitivity exponent of inactivation PME by HPCD at 55 ℃ are -383.00 cm³/mol and 16.40 MPa respectively.In contrst, the activation energy and the pressure sensitivity exponent at 15 MPa are 1 845.86 kJ/mol and 13.30 ℃ respectively.The residual activity of PME in peach juice is significantly greater than that in buffer after the same HPCD treatment, indicating that the original PME in the juice is less inactivated by HPCD.