The counterterrorism personnel commonly use the methods of the concentrated charge and multi-spot explosion to open fast track, rescue the hostage and capture the terrorists. The peak overpressures of the blast wave produced by above two methods are very high, which may easily cause unnecessary damage to the counterterrorism personnel. A new multi-spot short-delay controlled blasting technique is proposed in this paper. The experimental results show that the expansion bolts could be considered as the weakness of the burglarproof door in the door-explosion, and the peak overpressure of shock wave is effectively reduced by this new method. Moreover, the best dosage and safe distance in the blasting are obtained.

To investigate the combustion characteristics of base bleed propellant moving with the projectile in the gun bore, the closed bomb semi-physical and experimental simulation technology was employed. The combustion property under the condition of simulative high pressure in the gun bore was studied. Two average pressure-time curves corrected by heat loss were obtained under different charge density of the closed bomb. The correlation data between burning rate and pressure (8-150 MPa) were processed by smoothing, filtering and data transformation. The burning rate model adopting back propagation (BP) neural networks describing, which is suitable for high combustion pressure condition, was built based on training data samples. Comparing with the exponential burning rate model, the BP neural networks burning rate model of base bleed propellant has higher fitting precision and stronger robust.

The shock wave will be created in the process of generating electricity in the nuclear explosion fusion power plant, whose propagation law of overpressure is an important foundation for the design of cavity wall. However, there is a certain lack of describing the peak overpressure of shock wave in the existing equations (for example, relative error is great). A new equation of the peak overpressure of shock wave, the time of positive pressure τ₊ and the propagation coefficient of shock wave ω are suggested by theoretical analysis, from which we get the propagation law of shock wave. The comparative result indicates that the new equation is more suitable than the existing equations for solving the peak overpressure of shock wave in the power plant.

In the research fields of lignocellulosic materials, the physical-chemical properties are an important foundation for the resource conversion. Employing thermal gravimetric analysis, Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy methods, physical-chemical properties changes of steam exploded corn stalk were studied. The results of analysis showed that pyrolysis region of steam exploded corn stalk had a wider temperature range compared with the control substance, during which the maximum self-heating rate increased significantly and activation energies (E) decreased by 16.25%. The characteristic peak absorption intensity was significantly different. The hierarchical structure of the cell wall was completely destroyed, and crystallinity of lignocellulose decreased by 14.57%. Based on this analysis, a mechanism model of steam explosion pretreatment was constructed. The results indicate that physical-chemical properties of corn stalk are significantly affected by steam explosion pretreatment.

The activity of polyphenol oxidase (PPO) produced from Trametes Trogii was determined through using tea polyphenols as substrate. The pH value and the substrate concentration of strongest activity of PPO are 5.0 and 4 mg/mL, respectively. The activity of PPO processed by ultrahigh pressure of 100, 300 and 500 MPa for 10 min accounted for 93%, 87% and 86% of that of untreated one. The CD spectra of PPO processed by 100 and 300 MPa pressure respectively displayed folding shape and tillering shape of Cotton effect peak located in 190-210 nm, while the retention time of the first peak fraction (i.e., the maximum molecular weight fraction) of the two processed PPO on HPGPC profiles were advanced to 1.514 and 2.296 min, respectively from 6.678 min. Compared with control, CD spectrum and HPGPC of PPO treaded by 500 MPa showed more significant difference with only one positive Cotton effect peaks on CD spectra and reduced peak area of main components on HPGPC profiles (ie, the response value of 280 nm decreased). The disparity of CD and HPGPC of PPO treated by various UHPP showed the corresponding difference in the degree

In order to simulate and study the oblique hypervelocity impacts of space debris on bumper of spacecrafts, a series of oblique hypervelocity impact experiments of aluminum Whipple shields are carried out by a two-stage light gas gun. The aluminum alloy projectile diameter is 3.97 mm, the impact velocities range from 1.14 to 5.35 km/s, and the impact angles range from 0° to 70°. The crater distributions on the rear wall of aluminum Whipple shield obliquely impacted by aluminum spheres are obtained and analyzed. In addition, the forecast equations for crater distribution on the rear wall of aluminum Whipple shield by oblique hypervelocity impact are derived. The results indicate that there are two crater distribution areas on the rear wall under hypervelocity oblique impact. The critical fragmentation velocity of projectile will bring effect on the relationship between the impact damage law of rear wall and impact angle. For aluminum alloy Whipple shield, there exists a critical initial collision angle at which the impact damage on the rear wall is the most severe.

The effects of non-spherical projectile shape on hypervelocity impact are investigated for the cube and flake projectiles, which are the typical shapes of orbital debris in ORDEM2000 and Standard Breakup Model (SBM), by using AUTODYN-3D hydrocode simulations. The characteristics of the debris clouds produced by the hypervelocity impact based on the characteristic length of projectile are analyzed from their shape, mass, velocity and energy distributions, respectively, and are compared with the common used sphere projectile. The simulated results show that the shape and impact orientations of projectile have obvious influences on the debris cloud distribution, and moreover, the point impacts of the cube and flake have the maximum penetration capability, whereas the sphere is minimal. This means that the meteoroids and orbital debris impact risks of spacecrafts would be underestimated using the spherical projectile-based Ballistic Limit Curves (BLC). The projectile shape effects based on the real characteristic length of orbital debris will make more reasonable corrections for the BLC.

C-SiC composite is a new type of material which is being developed with aerospace technology. C-SiC composite possesses excellent properties and can satisfy the requirements of spacecraft protection system. Therefore it is very significant to study the mechanical behavior of C-SiC composite subjected to hypervelocity impact. Based on current simulations and experiments about C-SiC composite, a set of parameters which are essential for simulating C-SiC composite subjected to hypervelocity impact are derived in this paper. The characteristics of C-SiC composite dual-wall shield under hypervelocity impact and its ballistic limit curve are obtained by numerical simulations with AUTODYN, and furthermore, the ballistic limit equation is also developed.

In situ resistance measurement in a diamond anvil cell under high pressure and high temperature will be restricted by the thermal insulation. If the ordinary powder heat insulating material is used, it is difficult to introduce the electrode and measure resistance accurately. Here the in situ resistance measurement under high pressure and high temperature is performed successfully using a sputtered alumina film coated onto the surface of the top anvil plate as an insulation layer and a sputtered molybdenum film used as an electrode. With this device, the electrical conductivity of iron magnesium silicate [(Mg_0.875, Fe_0.125)₂SiO₄] under 31-35 GPa and 1 500-3 400 K is obtained. It is found that the activation energy increases with pressure, and the activation volume and activation energy are significantly reduced compared to that under the pressure and temperature lower than 15 GPa and 1 200 K.

The PA1010 (polyamide 1010)-SWCNT (single-walled carbon nanotube) nanocomposites crystallized at different temperatures and pressures for 30 min are prepared by an XKY-6×1200MN type high-pressure apparatus. The structure, crystallization behavior and morphological feature of high-pressure crystallized samples are studied by XRD (X-ray diffraction), DSC (differential scanning calorimetry), SEM (scanning electron microscope) and TEM (transmission electron microscope). The results show that high-pressure melt crystallization occurs in the pressure range of 1.0-2.5 GPa, while high-pressure annealing occurs in 3.0 and 4.5 GPa. Both melt crystallization and annealing under high pressure contribute to the thickening of polymer lamellar crystals, and moreover, the effect of high pressure melt crystallization is superior to that of high-pressure annealing. XRD results show that the triclinic form of PA1010 remains unchanged after high-pressure treatment, and both melt crystallization and annealing under high pressure can decrease (100) and (010) crystal plane spacing, and namely the high-pressure treatment results in close packing of polymer molecular chains. DSC results show that elevating the pressure and temperature during melt crystallization under high pressure can lead to the formation of crystals with larger lamella thickness, and the highest value of melting point and crystallinity obtained in the sample crystallized at 2.0 GPa and 350 ℃ are 208.5 ℃ and 64.6%, respectively. The large-sized crystals with c-axis thickness exceeding 150 μm are detected by SEM and TEM in the sample crystallized at high pressure. The interpenetrating network structure between the SWCNT and PA1010 matrix is formed, and the rigid SWCNT as high pressure nucleating agent can promote growth and thickening of PA1010 crystals under high pressure.