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71.
72.
为了降低弹体对硬目标深层侵彻的试验成本,结合"虚拟测试"(Virtual Test)在现代科技和工程技术领域的应用,提出了高冲击加速度虚拟测试技术的概念,从正面和反面两个角度分析了高冲击加速度虚拟测试系统的组成,使试验在实际进行前可以通过该系统预测试验结果和可能出现的问题,从而大幅度缩短产品的研制周期和研制经费. 相似文献
73.
电子商务安全审计系统的设计与实现 总被引:7,自引:0,他引:7
由于系统软件设计漏洞的无法预料,黑客攻击手段的不断变化,传统网络安全产品已不能满足黑客重点攻击的电子商务服务器系统的安全要求。该文在分析基于主机和基于网络的入侵检测系统的特点的基础上,提出了一种电子商务安全审计系统的设计。 相似文献
74.
Kono Y Park C Sakamaki T Kenny-Benson C Shen G Wang Y 《The Review of scientific instruments》2012,83(3):033905
An integration of multi-angle energy-dispersive x-ray diffraction and ultrasonic elastic wave velocity measurements in a Paris-Edinburgh cell enabled us to simultaneously investigate the structures and elastic wave velocities of amorphous materials at high pressure and high temperature conditions. We report the first simultaneous structure and elastic wave velocity measurement for SiO(2) glass at pressures up to 6.8 GPa at around 500°C. The first sharp diffraction peak (FSDP) in the structure factor S(Q) evidently shifted to higher Q with increasing pressure, reflecting the shrinking of intermediate-range order, while the Si-O bond distance was almost unchanged up to 6.8 GPa. In correlation with the shift of FSDP position, compressional wave velocity (Vp) and Poisson's ratio increased markedly with increasing pressure. In contrast, shear wave velocity (Vs) changed only at pressures below 4 GPa, and then remained unchanged at ~4.0-6.8 GPa. These observations indicate a strong correlation between the intermediate range order variations and Vp or Poisson's ratio, but a complicated behavior for Vs. The result demonstrates a new capability of simultaneous measurement of structures and elastic wave velocities at high pressure and high temperature conditions to provide direct link between microscopic structure and macroscopic elastic properties of amorphous materials. 相似文献
75.
Based on a strong inter-diagonal matrix and Taylor series expansions,an oversample reconstruction method was proposed to calibrate the optical micro-scanning error.The technique can obtain regular 2 × 2 microscanning undersampling images from the real irregular undersampling images,and can then obtain a high spatial oversample resolution image.Simulations and experiments show that the proposed technique can reduce optical micro-scanning error and improve the system's spatial resolution.The algorithm is simple,fast and has low computational complexity.It can also be applied to other electro-optical imaging systems to improve their spatial resolution and has a widespread application prospect. 相似文献
76.
In this paper the fiber trajectory stability of filament wound toroidal pressure vessels is evaluated for two most frequently used patterns: single helical winding, helical and hoop winding. The basic equations of equilibrium for fibers on a torus are given based on netting analysis. The governing equations that determine helical winding angles along the meridional direction are derived for the two winding patterns. The slippage coefficients of the obtained fiber trajectories are calculated using the non-geodesic law and differential geometry. The condition between the hoop-to-helical thickness ratio and the relative bend radius of the toroid is also formulated to prevent fiber bridging on the concave surface. The fiber slippage and bridging tendencies are outlined and compared, corresponding to various relative bend radii and hoop-to-helical thickness ratios. The results show that the single helical winding process provides better stability of fiber trajectories, in terms of both fiber slippage and bridging, than the helical and hoop winding. The toroidal vessel with larger relative bend radius requires lower coefficient of friction between the fiber bundle and the supporting surface. The present analysis for fiber trajectory stability affords a useful reference tool for designing filament-wound toroidal pressure vessels. 相似文献
77.
Weiwei Wu Lingling Wang Li Wang Yuangang Zu Lu Wang Yin Zhang Xiuhua Zhao 《化学工程与技术》2019,42(2):414-421
To improve the aqueous solubility and dissolution rate of taxifolin, taxifolin form II was successfully prepared through antisolvent recrystallization, in which 1‐butyl‐3‐methylimidazolium tetrafluoroborate and dichloromethane were used as solvent and antisolvent, respectively. The properties of taxifolin form II were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X‐ray diffraction, differential scanning calorimetry, solid‐state NMR spectroscopy, the dissolving capability test, and the bioavailability test. The chemical structure of taxifolin form II was not changed, but its morphology and crystalline structure changed during the recrystallization process. Moreover, taxifolin form II showed higher solubility, faster dissolution rate, and better bioavailability than taxifolin form I. 相似文献
78.
Sheng-Zhen Zu Li-Juan Mao Abdelhamid Sayari Bao-Hang Han 《Journal of Porous Materials》2012,19(5):745-749
We here report a facile synthesis route to monodispersed platelet-like SBA-15 mesoporous silica employing kinetically controlled micelles as templates. In previous preparations of SBA-15 silica, it was believed that thermodynamically equilibrated micelles were used as templates. The kinetically controlled micelle has never been used before to generate periodic mesoporous materials with unique morphology. Monodispersed hexagonal platelet-like SBA-15 microparticles were prepared via a very facile synthesis route by tuning the micelle formation process, i.e. the stirring rate and the time of dissolution of the triblock copolymer and formation of the micelles. Shorter micelle formation time and faster stirring are essential to generate platelet-like SBA-15 silica particles. It is expected to apply in the synthesis of a wide variety of mesophase materials. 相似文献
79.
Effect of superfine grinding on physicochemical and antioxidant properties of pomegranate peel
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Chen Zhong Yuangang Zu Xiuhua Zhao Yong Li Yunlong Ge Weiwei Wu Yin Zhang Yuanyuan Li Dongjie Guo 《International Journal of Food Science & Technology》2016,51(1):212-221
Pomegranate peel powders were prepared by superfine grinding, whose effects were investigated on the composition, functional and antioxidant properties of the pomegranate peel products. Fluidised bed jet milling technology was used to process superfine pomegranate peel powder. The physical–chemical properties of coarse powder A (D50 = 413.4 μm) and B (D50 = 197.1 μm), fine powder C (D50 = 142.6 μm) and D (D50 = 41.2 μm), superfine powder E (D50 = 7.68 μm) and raw material powder (RMP) (D50 = 352.2 μm) were investigated in this study. SEM images revealed the shape and surface morphology of six pomegranate peel powders. The physical determinations showed that the smaller the powder particle size was, the greater the surface area (from 0.214 to 1.597 m2 g?1) and bulk density (from 0.653 to 0.751 g mL?1) were, the smaller the angles of repose (from 51.69° to 38.74°) and slide (from 48.32° to 34.18°) were. The water holding capacity (WHC), water‐solubility index (WSI), polyphenols and flavonoids release were significantly improved as the size of pomegranate peel particle decreased. The results of FTIR and UV indicated that grinding process would not influence chemical composition of pomegranate peel. Vitamin C (VC) and butylated hydroxytoluene (BHT) were used in DPPH scavenging activity determination, and DPPH scavenging activity was A < RMP < BHT < B < C < D < E < VC. 相似文献
80.