区块链环境下基于秘密共享的数字权限管理方案

针对数字权限保护中对内容加密密钥的安全保存和有效分发的需求,提出了一个区块链环境下基于秘密共享的数字权限保护方案。该方案主要包括系统初始化、内容加密、许可授权和内容解密4个协议。在该方案中,利用Pedersen可验证秘密共享方案和属性基加密（ABE）算法来实现内容加密密钥的保护和分发,将内容提供商从管理内容加密密钥的任务中解放出来,从而确保了密钥管理的安全性和灵活性。此外,基于区块链的数字权限保护方案具有信息公开透明、不可篡改等特点。安全性分析表明,该方案在区块链环境下是安全可行的;仿真实验结果表明,该方案能够以较低的开销实现数字内容的权限保护。     

一种支持分级用户访问的文件分层CP-ABE方案

文件分层的密文策略基于属性的加密（FH-CP-ABE）方案实现了同一访问策略的多层次文件加密,节省了加解密的计算开销和密文的存储开销.然而,目前的文件分层CP-ABE方案不支持分级用户访问,且存在越权访问的问题.为此,提出一种支持分级用户访问的文件分层CP-ABE方案.在所提方案中,通过构造分级用户访问树,并重新构造密文子项以支持分级用户的访问需求,同时消除用户进行越权访问的可能性.安全性分析表明,所提方案能够抵御选择明文攻击.理论分析和实验分析均表明,与相关方案相比,所提方案在计算和存储方面具有更高的效率.     

一种新的基于属性的广播签名算法

针对现有基于ABE广播签名算法的复杂性,提出了一个新的基于属性的广播签名算法。现有的基于ABE的广播网签名算法,每次通信需要传输签名认证所需的线性秘密共享矩阵M,在通信量和用户存储能力上要求很高。该文的基于属性的签名算法是在CP-ABE的基础上发展来的,但此算法使用了新的接入策略,即使用求最大公约数（GCD）的方法取消了对线性秘密共享矩阵M的需求,接收者只需计算3个双线性对即可完成签名认证。此算法降低了通信量和接收者运算复杂度,对某些能量受限的网络,如AdHoc网络,有很好的适应性。     

基于属性的分布式云访问控制方案

云服务中现有访问控制方案对可信第三方具有强烈依赖性。针对该问题,提出一个基于属性的分布式云访问控制方案。建立云访问控制模型,采用ABE的加密树方式构造访问控制策略,并给出用户撤销及策略更新方法。安全性分析表明,该方案能够抵抗共谋攻击,具有数据保密性以及后向前向保密性。     

Adsorption of butanol from aqueous solution onto a new type of macroporous adsorption resin: Studies of adsorption isotherms and kinetics simulation

BACKGROUND: Owing to the rapid depletion of petroleum fuel, the production of bio‐butanol has attracted much attention. However, low butanol productivity severely limits its potential industrial application. It is important to establish an approach for recovering low‐concentration butanol from fermentation broth. Experiments were conducted using batch adsorption mode under different conditions of initial butanol concentration and temperature. Batch adsorption data were fitted to Langmuir and Freundlich isotherms and the macropore diffusion, pseudo‐first‐ and second‐order models for kinetic study. RESULTS: The maximum adsorption capacity of butanol onto KA‐I resin increase with increasing temperature, ranged from 139.836 to 304.397 mg g^?1. The equilibrium adsorption data were well fitted by the Langmuir isotherm. The adsorption kinetics was more accurately represented by the macropore diffusion model, which also clearly predicted the intraparticle distribution of the concentration. The effective pore diffusivity (D_p) was dependent upon temperature, but independent of initial butanol concentration, and was 0.251 × 10^?10, 0.73 × 10^?10, 1.32 × 10^?10 and 4.31 × 10^?10 m² s^?1 at 283.13, 293.13, 303.13 and 310.13 K, respectively. CONCLUSION: This work demonstrates that KA‐I resin is an efficient adsorbent for the removal of butanol from aqueous solutions and available for practical applications for future in situ product recovery of butanol from ABE fermentation broth. Copyright © 2012 Society of Chemical Industry     

Biobutanol: science,engineering, and economics

Among several liquid alternative fuels, biobutanol has shown great promise because of its very similar properties to gasoline. This review provides an overview of research activities in acetone–butanol–ethanol (ABE) fermentation over the past two and a half decades. We have addressed seven important facets of ABE fermentation, viz. biochemistry, microbial cultures, alternative substrates, solvent recovery, fermentation mode and reactor designs, mathematical modeling, and economics. Development of mutant strains having higher yield, selectivity and tolerance to inhibition, and search for cheap alternative substrates for fermentation are most important thrust areas in biobutanol production. New and efficient processes have been developed for in situ removal and recovery of the ABE solvents. Several rigorous kinetic and physiological models for fermentation have been formulated, which form useful tool for optimization of the process. These research activities have been reviewed in this paper. Finally, we have summarized studies on the economic viability of large‐scale ABE fermentation processes employing various process designs, substrates, and microbial cultures. With the use of new strains, inexpensive substrates, and superior reactor designs, economic potential of ABE fermentation has been found to be highly attractive. Research efforts in science, engineering, and economics of ABE fermentation have brought biobutanol close to commercialization as liquid alternate fuel. Copyright © 2011 John Wiley & Sons, Ltd.     

Combustion and emission characteristics of an Acetone-Butanol-Ethanol (ABE) spark ignition engine with hydrogen direct injection

Butanol could reduce emissions and alleviate the energy crisis as a bio-fuel used on engines, but the production cost problem limits the application of butanol. During the butanol production, ABE (Acetone-Butanol-Ethanol) is a critical intermediate product. Many studies researched the direct application of ABE on engines instead of butanol to solve the production cost problem of butanol. ABE has the defects of large ignition energy and vaporization heat. Hydrogen is a gaseous fuel with small ignition energy and high flame temperature. In this research, ABE port injection combines with hydrogen direct injection, forming a stratified state of the hydrogen-rich mixture around the spark plug. The engine speed is 1500 rpm, and λ is 1. Five αH₂ (hydrogen blending fractions: 0, 5%, 10%, 15%, 20%) and five spark timings (5°, 10°, 15°, 20°, 25° CA BTDC) are studied to observe the effects of them on combustion and emissions of the test engine. The results show that hydrogen addition increases the maximum cylinder pressure and maximum heat release rate, increases the maximum cylinder temperature and IMEP, but the exhaust temperature decreases. The flame development period and flame propagation period shorten after adding hydrogen. Hydrogen addition improves HC and CO emissions but increases NO_x emissions. Particle emissions decrease distinctly after hydrogen addition. Hydrogen changes the combustion properties of ABE and improves the test engine's power and emissions. The combustion in the cylinder becomes better with the increase of αH₂, but a further increase in αH₂ beyond 5% brings minor improvements on combustion.     

丙酮-丁醇-乙醇(ABE)/汽油混合燃料对高速发动机性能影响的试验研究

以发动机4000r/min、节气门开度35%为试验工况,对纯汽油及不同掺混体积分数丙酮-丁醇-乙醇(acetone-butanol-ethanol,ABE)与汽油混合物开展了不同点火提前角和喷油量的试验研究。分析了不同ABE混合比、点火提前角和过量空气系数对发动机性能的影响,并对每种燃料发动机最大功率工况的性能参数进行了比较。结果表明：点火提前角和过量空气系数相同时,混合燃料中ABE含量越高,燃油流量越大,发动机功率越大,有效热效率越高;燃油流量的总热量增大和热-功转换效率提高是促使发动机功率增大的主要原因;随ABE掺混比增加,NO比排放明显降低,CO比排放略有增加,碳氢化合物比排放先增后减。浓混合气工况增加ABE含量比在当量空燃比状态下增加ABE含量,发动机的有效热效率增大更明显,发动机的NO比排放降低更加明显。研究表明高速汽油机掺混ABE燃料具有较好的应用前景。     

可证安全的基于属性密钥交换

分析了密钥交换协议的特点,提出了一种基于属性的密钥交换协议,能够更灵活地控制不同用户参与密钥交换的权限,该协议基于Sahai-Waters ABE体制,只需要一轮消息通信。研究了密钥交换协议的安全需求,应用＂敌手-挑战者＂游戏,提出了基于属性密钥交换协议的语义安全性定义,进一步在标准模型中证明了协议的安全性。