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现有的委托授权模型主要侧重于受托方是否具有执行委托任务(权利)的能力,没有考虑到受托方平台的可信性;基于此,提出了多媒体环境下基于远程证明(Remote Attestation,RA)的委托授权安全协议,实现了对多媒体数字内容的可信委托授权.协议既保证了委托方对受托方身份与平台完整性的信任、多媒体资源服务器对受托方身份与平台完整性的信任,也实现了多媒体内容的安全访问.阐述了委托验证过程、实体间消息的交互过程以及委托授权可用性验证过程.列举与分析了协议可能遭遇的攻击,同现有的协议相比,应用于数字版权保护(Digital Rights Management,DRM)的委托授权远程证明协议的委托授权过程安全性更高,功能更完善. 相似文献
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为进一步补充药类物质水溶液扩散系数的实验数据和研究相关理论模型的实用性,今制备了金属膜池,用氯化钾溶液标定了膜池常数,并用已有可靠扩散系数值的蔗糖水溶液验证了装置的可靠性.测定了298.15K到328.15K不同温度下L-抗坏血酸在水溶液中可溶解范围内不同浓度下的扩散系数.结果表明在相同温度下,L-抗坏血酸水溶液的扩散系数随着浓度的增加而减小;在同一浓度下,随着温度的升高而增加.另一方面Gordon在扩散模型基础上,关联得到一个有温度项的扩散系数半经验模型,计算结果与实验值吻合很好. 同时用精密密度计和粘度计测定了体系相应的密度和粘度,并与浓度进行了关联. 相似文献
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Visosities and densities at ,several temperatures from 293.15 K to 313.15K are reported for L-ascorbic acid in aqueous glucose and sucrose solutions at different concentrations.The parameters of density,Viscosity coefficient B and partial molar volume are calculated by regression.The experimental results show that densities and viscositis decrease as temperature increases at the same solute and solvent (glucose and sucrose aueous solution)concentrations,and increase with concentration of glucose and sucrose at the same solute concentration and temperature,B increases with concentration of glucose and sucrose and temaperature,L-ascorbic acid is sturcture-breaker or structure-making for the glucose and sucrose aqueous solutions ,Furthermore,the solute-solvent interactions in ternary systems of water-glucose-electrolyte and water-sucrose-electrolyte are discussed. 相似文献
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Experimental densities, viscosities and heat capacities at different temperatures were presented over the entire range of mole fraction for the binary mixture of p-xylene and acetic acid. Density values were used in the determination of excess molar volumes, VE. At the same time, the excess viscosity and excess molar heat capacities were calculated. The values of V^E, η^E and cE/p were fitted to the Redlich-Kister equation. Good agreements were observed. The excess molar volumes are positive with a large maximum value located in the central concentrationrange. The excess viscosity has an opposite trend to the excess molar volume V^E. η^E values are negative over the entire range of the mixture. The cure of dependence of c E/p on concentration has a special shape. The molecularinteraction between v-xvlene and acetic acid is discussed. 相似文献
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A polyaluminium chloride solution with high Al 13 content self-prepared was used as material for preparing the spherical γ-Al 2 O 3 by the sol-gel and oil-drop method. Polyethylene glycol with different molecular mass was used as surfactant to investigate the effect on property of γ-Al 2 O 3 . The physical property was characterized by 27 Al NMR (nuclear magnetic resonance) spectra, X-ray diffraction, FT-IR (Fourier transform infrared spectroscopy) and TG-DTA (thermogravimetric-differential thermal analysis). The results showed that surface area, pore volume and pore size of γ-Al 2 O 3 all increased with the increase of polyethylene glycol molecular mass in the experimental research range, and polyethylene glycol 10000 was the most suitable pore forming additive. γ-Al 2 O 3 with surface area of 339 m 2 ·g 1 , pore volume of 0.59 cm 3 ·g 1 and pore diameter of 6.9 nm were obtained at 450 °C. 相似文献
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纳滤膜去除饮用水中Cr(Ⅵ)的应用研究 总被引:1,自引:0,他引:1
分别采用自制的芳香聚酰胺平板纳滤膜和某芳香聚酰胺平板纳滤膜商品处理模拟含铬饮用水,考察其处理效果及影响因素。结果表明:在Cr(Ⅵ)浓度为50~250μg/L、pH值为7左右、操作压力为0.5 MPa、温度为25℃的条件下,两种纳滤膜对Cr(Ⅵ)的截留效果均较好,出水Cr(Ⅵ)浓度均低于0.05 mg/L(GB 5749—2006的限值),且截留率均随Cr(Ⅵ)浓度的升高而下降,膜通量则基本不变;随着操作压力的增加,两种纳滤膜对Cr(Ⅵ)的截留率均呈上升趋势,膜通量也大幅增加;进水pH值越高,则纳滤膜对Cr(Ⅵ)的截留效果越好,但膜通量无明显变化。 相似文献
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A direct contact membrane distillation (DCMD) process was applied to prepare high concentration polyaluminum chloride (PACl) with high Alc content. The changes in total Al concentration (AlT) and Al species distribution were investigated. The results showed that AlT increased but the flux decreased with operating time during the DCMD process. The Alc content increased from 65% to 81% while the Alb content decreased from 34% to 18%, and the Ala content was almost 1% in the process. 2.1 mol8226;L61485;1 PACl with 81% Alc was successfully prepared by DCMD method. Thus the DCMD is an effective method for preparing high concentration PACl with high Alc content. 相似文献