On the basis of the compressible gasket model presented by Wakatsuki, we investigated the squeezing behavior of a pyrophyllite gasket using a Bridgman type high pressure apparatus with an anvil top diameter of 20 mm.A series of data including the critical thickness, the elastic region diameter, the compression spring-back rate etc., were measured under different loading forces.Combining with the pressure calibration at the center of the gasket, the image-analysis of recovered discs and related calculations, we described the evolution of the mechanical state and pressure distribution in the elastic and plastic regions of gasket along with the increase of the loading force, and then estimated the region of quasi-hydrostatic pressure in the gasket.The experimental results show that the increase rate of the center pressure with the loading force shows an upward trendency, which is a feature of the Bridgman anvils.

To investigate the penetration performance of segmented rods against targets, a series of numerical simulations were conducted to research the penetration performance of tungsten alloy segmented rods with various configurations and their corresponding continuous rods into semi-infinite thick 4340 steel targets at velocities ranging from 1 500 to 3 500 m/s by using the SPH (Smooth Particle Hydrodynamics) hydro code of AUTODYN.The shape of the crater and the depth of penetration were in good agreement with the results obtained from experiments.The numerical results indicate that the penetration performance of segmented rods is significantly improved compared with that of continuous rods under some conditions.The penetration efficiency of segmented rods depends on the s/d value (where s is the segment spacing and d is the rod diameter) and the impact velocity.Moreover, there is an optimum s/d for the segmented rods which depends on the impact velocity and configuration of projectiles.The calculations show that there are significant differences in the crater profile of targets between continuous and segmented rods, and also those of segmented rods at high and low velocities are different.

The formation processes of the radial shaped charge jet with different modes of initiation—center-point initiation, endpoint initiation and two-side symmetric initiation—were simulated using LS-DYNA finite element code.Our calculated results show that, comparatively speaking, the head velocity of the jet produced by two-side symmetric initiation is the highest, and that by center-point initiation takes the second place, while that by endpoint initiation is the lowest.Different initiation modes result in different angles between the detonation wave and the generatrix of the outside liner, and the smaller the angle, the higher the detontion load and collapse velocity, and the better the jet performaces.Meanwhile, under the circumstances of endpoint initiation, the detonation load and collapse velocity of the liner elements of both sides are different due to the liner asymmetry of detonation wave, which results in jet offset.

We first deeply analyzed the reason why the exact Riemann sovler, MFCAV (Multi fluid channel on averaged volume) Riemann solver and Dukowicz Riemann solver cannot be applied directly to the compatible Lagrangian method and then, by introducing a new general nodal solver, we successfully applied the 3 Riemann solvers to the Lagrangian method.Combing the new Lagrangian method with efficiency remesh and remapping technology, we developed a new cell-centered compatible ALE (Arbitrary Lagrangian and Eulerian) method based on arbitrary Riemann solvers.Several numerical examples show that the new ALE method not only has the advantages of the new compatible Lagrangian method, but also has the ability to deal with the large deformation problems.

The terminal-sensitive ammunition fitted with a central feedback layout for millimeter wave sensitive system needs to be embeded with some sensitive devices in the charge of EFP (Explosively formed penetrator) warhead, resulting in changing the charge structure, affecting observably the detonation wave propagation, and producing significant negative effects on the shaping process of EFP.In order to get a large L/D ratio of the penetrator, we proposed to use an eccentric spherical liner structure to adjust the thickness of the liner, which successfully changed the pressing process of the liner and made it turn backwards.The experimental shape parameters and speed indicators basically meet with the predicted results of the numerical simulation.With the eccentric spherical liner, EFP warhead can be formed with a large L/D ratio and good flight stability.This design removes the negative effects produced on the warhead shaping by the embeded sensitive devices.

One dimensional plate micro-spall impact experiments were performed on two samples of melted tin with different surface roughness using our own newly developed momentum device to measure the momentum of the ejecta at different positions and moments.Using the Autodyn Smooth Particle Hydrodynamics (SPH) solver, we simulated the microscopic process of the shock-induced micro-spall underneath the sample surface and investigated the evolution of the interfacial instability along with the transmission of the reflective wave in the unloading process.The study shows that the surface roughness of several micro-meters can lead to significant growth of disturbance during the wave reflection, and that the fully fragmented particles of the melted metal bearing both longitudinal and radial transversal speed components are in agreement with those of the experimental results.

According to Lenz's law, to prevent the drive coil current from decreasing during the launching process of coilgun, the magnetic field generated by the armature eddy current is in the same direction with the drive coil.And affected by the capture effect, the armature will induce a deceleration force, which reduces its muzzle velocity and the launching efficiency.In order to reduce the influence of armature capture effect, a resistor or a capacitor was connected in series in the discharge circuit.Based on the theory and simulation, we analyzed the effect of the improved peripheral circuits on reducing the armature capture effect, which was verified by building a single-stage coilgun experimental system.This study found that a suitable big resistor or small capacitor connected in series in the discharge circuit can speed up the release of the remaining current of the drive coil, effectively reduce the armature capture effect, increase the armature's muzzle speed, and improve the coilgun's launching performance.

Based on the control principle for exposure time of the ultra high speed framing camera, we examined the errors in the measurement of the gating time using a CCD to record the time-delay produced by the ultra-fast laser pulse and the fiber array, from pserpectives of the fiber cutting precision and laser precise synchronization, and presented a specific value.We offered a comprehensive analysis of the effect resulting from these two aspects for measuring the gating time of the ultra high speed framing camera, and then proposed some technical measures to reduce the error.The results show that the errors caused by the fiber cutting precision and laser precise synchronization are in picosecond scale, which is negligible for the gating time measurement of a nanosecond camera.Finally, we used this method to measure the gating time of the ultra high speed camera.The measured results show good agreement with the normal values, which verifies the effectiveness of this method.

The effects of 100, 200 and 500 MPa high hydrostatic pressure (HHP) treatments on spinach thylakoid membrane chlorophyll content, soluble protein content, chlorophyll absorption spectra, chlorophyll emission and excitation fluorescence spectra, protein fluorescence spectra were assessed in this study.The results show that the HHP-treated samples have higher chlorophyll content and soluble protein content, higher absorption spectra capacity, higher chlorophyll emission and excitation fluorescence spectra capacity than those of the thermal-treated.This is especially obvious for the samples that have received 100 and 250 MPa HHP treatments, for they maintain functional activity of harvesting light and have high excitability.Meanwhile, protein composition of thylakoid membrane undergoes some change after HHP treatment, suggested by great difference in protein fluorescence spectra.It is speculated the preservation of thylakoid membrane function plays a positive role for better green color retention in HHP-treated vegetables.

The effects of high pressure treatment on enzymatic hydrolysis of casein hydrolyzed by trypsin and antioxidant activities of protein hydrolysates were investigated.Based on our measured data of hydrolysis (DH), DPPH radical, superoxide anion radical, hydroxyl radical scavenging activities and reducing power, we studied the hydrolysates and antioxidant activities as resulting from the high-pressure treatment of enzymatic hydrolysis of casein, trypsin, with and without the addition of casein to each and all of them.The results show that the high pressure treatment has a better effect on casein than on trypsin in terms of the DH which increases by 31.14% under the optimal condition of 200 MPa for 20 min, while the treatment effect is not as satisfactory for casein-trypsin mixture.In cases of DPPH and hydroxyl radical scavenging activities, the high pressure has a greater effect on trypsin compared with that on casein under 100 MPa/15 min or 50 MPa/5 min.Besides, the hydroxyl radical scavenging activity of casein treated at 150 MPa for 10 min and the reducing power of casein-trypsin mixture processed under 150 MPa for 15 min increase more markedly.Moreover, no correlation has been found between the antioxidant activities of the hydrolysates and their enzymatic properties.

Ultra-high pressure (UHP) treatment, as a burgeoning non-thermal food-processing technology, is convenient and promises great potentialities for application in food industry.We selected 3 representative complex seasonings, composite soybean paste, composite sweet soybean paste and composite sesame paste, in our experiments to investigate the effect of CO₂ assisted UHP treatments on their aerobic plate count, viscosity, color and flavor.The results show that, after CO₂ assisted UHP treatment, the total bacteria number of all the 3 complex seasonings is reduced, and the higher the pressure, the greater the reduction, but the reductions are all less than one logarithmic unit.Our findings also show that there is no significant change in viscosity regularity between samples before and after the treatments, only the color of composite sesame paste samples undergoes significant changes, and the type and content of flavor compounds change with different degrees.Sensory evaluation reveals that at the 5% significant level, CO₂ assisted UHP treatment shows no significant effect on complex seasonings.The treatment of 500 MPa, 5 min at room temperature is the optimum.This research provides reference for the application of UHP technology in seasonings production.