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71.
72.
针对连续不确定XML数据概率阈值范围查询,提出一种新的CUXI索引树。该索引树的构建方法是借鉴U树对空间数据自顶向下递归构建索引树的思想,将连续不确定XML文档中具有相同父亲的叶子节点构建二维数据矩形,在聚类的基础上来构建相应的CUXI索引树,其中叶子节点存储连续不确定数据辅助信息。为了提高查询效率,对连续不确定数据制定了过滤策略,通过遍历索引树过滤掉不满足查询范围的子树。理论和实验结果表明,此索引技术可提高查询处理的性能。 相似文献
73.
In quantum key distribution (QKD), the information theoretically secure authentication is necessary to guarantee the integrity and authenticity of the exchanged information over the classical channel. In order to reduce the key consumption, the authentication scheme with key recycling (KR), in which a secret but fixed hash function is used for multiple messages while each tag is encrypted with a one-time pad (OTP), is preferred in QKD. Based on the assumption that the OTP key is perfect, the security of the authentication scheme has be proved. However, the OTP key of authentication in a practical QKD system is not perfect. How the imperfect OTP affects the security of authentication scheme with KR is analyzed thoroughly in this paper. In a practical QKD, the information of the OTP key resulting from QKD is partially leaked to the adversary. Although the information leakage is usually so little to be neglected, it will lead to the increasing degraded security of the authentication scheme as the system runs continuously. Both our theoretical analysis and simulation results demonstrate that the security level of authentication scheme with KR, mainly indicated by its substitution probability, degrades exponentially in the number of rounds and gradually diminishes to zero. 相似文献
74.
运用改进型内梅罗污染指数法评价玛纳斯河流域地表水水质,结果表明各监测断面丰、枯、平3个水期中,丰水期水质状况最差;4个监测断面中玛纳斯河水质状况最好,蘑菇湖水库水质状况最差,其内梅罗污染数值接近4;五项水质评价指标中,石油类及BOD5是研究区内超标最严重的两项评价因子;3个水期内,研究区整体评价等级均为Ⅳ类中度污染. 相似文献
75.
Robust‐Adaptive Control Strategies for a Time Delay Bioelectrochemical Process Using Interval Observers 下载免费PDF全文
The paper addresses the design and the analysis of adaptive and robust‐adaptive control strategies for a complex recycled wastewater treatment bioprocess. The design procedures are developed under the realistic assumptions that the bacterial growth rates are unknown and the influent flow rates are time‐varying and uncertain, but some lower and upper bounds of these uncertainties are known. The proposed control structures are achieved by combining a linearizing control law with an appropriately (asymptotic or interval based) state observer and with a parameter estimator used for on‐line estimation of unknown kinetics. These approaches are applied to a complex time delay bioprocess resulting from the association of a recycling bioreactor with an electrochemical reactor. Numerical simulations are performed in order to validate the proposed algorithms. 相似文献
76.
随着大容量智能卡的推广应用,卡数据的安全问题越来越重要,如果卡数据得不到有效的防护,将制约业务的开展,甚至造成用户财产的损失,因此保证卡数据安全是运营商急待解决的问题。本文分析了目前适用于大容量智能卡上的安全策略,并对运营商开展大容量卡业务时需要用到的加密算法提出建议。 相似文献
77.
网络编码自提出以来得到了巨大的发展,并且在许多方面被广泛应用。网络安全是网络编码的重要的应用领域之一。安全网络编码最主要的两方面就是防窃听和防拜占庭攻击,实质上就是防搭线窃听与网络纠错。本文构造了一种基于范德蒙德行列式的随机网络编码,并通过添加Target位的方法来实现抗拜占庭攻击;对于同时具备窃听和修改能力的攻击者,设计了一种改进的借助数据位的Target位构造方法;针对攻击者可能仅修改部分数据的具体情况给出了一种变步进多Target位的解决方案,即通过构造步进函数的方式来选取多个数据,构造多个Target位来提高数据安全性,并且通过部分数据验证了其可行性。 相似文献
78.
Rapid mobile phone market growth has drastically shortened design cycle times forcing designers to identify user preferences quickly. Two studies test a novel method to quickly determine design preferences for touch screen and non–touch screen mobile phones. Interactive Genetic Algorithms (IGAs) are tested as an option for preference identification. IGAs efficiently explore design spaces, finding user preferences via an iterative system mimicking evolution. Each study tested six independent variables: horizontal and vertical button spacing; horizontal and vertical screen dimensions; corner radius; and user’s goal between aesthetically pleasing, functional, and both aesthetic and functional (first experiment), and aesthetic preference differences between touch screen and non–touch screen mobile phones for dialing phone numbers only (second experiment). Results showed IGAs to be a viable method; participant preference varied by goal (horizontal button spacing and screen width were most effected). Designers can employ IGAs to quickly determine aesthetic and other user preferences. 相似文献
79.
Assessment of Sustainable Yield of Karst Water in Huaibei,China 总被引:2,自引:1,他引:1
Dan Yin Longcang Shu Xunhong Chen Zhenlong Wang Mokhatar Eisa Mohammed 《Water Resources Management》2011,25(1):287-300
This paper presents the assessment of sustainable yield in the Huaibei karst water area of Anhui province, China. A review
of sustainable yield definition is introduced first in this paper, and sustainable development in karst areas is more difficult
due to the complicated hydrogeologic conditions. General hydrogeology of the study area is provided to characterize hydraulic
connections between the karst aquifer and an overlying porous aquifer. Groundwater level declines continuously due to over-exploitation
of the karst groundwater, and two layers of groundwater dropping funnel were formed in Huaibei. These problems not only threaten
the eco-geo-environment, but also compromise the water utilization which depends on the shallow porous water. A “critical
water level” is proposed in this study to assess the sustainable yield, and it is determined by the historical exploitation
data which represent the relationship between the karst water and the shallow porous water uses. A three layer Artificial
Neural Network (ANN) model is used to understand the complex relationship of the karst water level and its influencing factors.
Precipitation, exploitation and water level of latest period are chosen as the input nodes, seasonal records of water level
are simulated by the ANN model. The sustainable yield is calculated by the trail-and-error adjusting method, and is equal
to the pumping rate when the “critical water level” is maintained. The rate of 30.05 MCM/a is the sustainable yield for the
Huaibei karst area in 2008, and it is less than the real pumping rate of 35.92 MCM/a. This assessment is meaningful to the
management for the Huaibei karst water. 相似文献
80.