污水处理厂污泥厌氧消化优化设计与运行探讨

对国内典型的污水处理厂污泥厌氧消化系统进行调研发现,厌氧消化系统的运行管理尚存在诸多问题。在总结白龙港污水处理厂污泥厌氧消化调试与运行管理经验的基础上,针对厌氧消化工艺存在的普遍性问题,提出了厌氧消化系统设计和运行管理方面的建议,以促进工艺设计优化,提高运行管理水平。     

非圆曲线的数控处理及程序实现

引用优化设计中一维搜索和黄金分割法,针对数控加工中非圆曲线的处理,给出实用、简洁和新颖的宏程序实现方法,解决在数控系统中求解方程组的问题,是数控用户快速解决相关应用问题的有效手段。     

具有区间峰值的曲面伸缩因子及其实验

为了改进参数曲面自由变形方法,构造了一种新的伸缩因子函数,它不仅具有以往文献所引入的伸缩因子的特性,还可以在区域上达到峰值,从而克服现有的伸缩因子仅在一点达到峰值的不足。使用新的伸缩因子去作用待变形的曲面方程,从而使曲面发生形变,通过交互改变控制参数来控制曲面的形状,使其能够更好地表示一些实体的外型。实验表明,该方法数学背景简单,易于控制,重复使用可获得丰富的变形效果。适用于几何造型、计算机动画、CAD/CAM等领域。     

时间分层的基于身份密码技术的算法和系统

基于椭圆曲线和Weil配对数学理论发明了具体可实施的基于身份密码的技术方案,但其一大缺陷就是密钥更新问题.介绍了一种时间分层的基于身份密码技术的算法和系统,其采用多个主密钥分量,逐级更新用户私钥,与PKG对接的顶级中间设备的帮助密钥更新时间相对较长,而用户终端保存的用户私钥更新时间相对较短,这样既满足了用户私钥更新频度的需要,又不引起系统频繁更新用户私钥所造成的沉重负荷.     

均匀二重混合双曲多项式B样条曲线

为扩展B样条曲线,提出1种均匀二重混合双曲多项式B样条曲线. 该样条曲线在span{sinh t,cosh t,tsinh t,tcosh t,1,t,…,tk-6,tk-5}空间上均匀产生,其中k是大于等于5的整数. 证明k阶二重混合双曲多项式B样条基的性质和二重混合双曲多项式B样条曲线的性质. 二重混合双曲多项式B样条曲线精确地包含双曲多项式B样条曲线. 给出这种新样条曲线的细分公式并证明其有变差缩减性质和细分控制多边形逼近性质. 该性质使得通过递归细分得到曲线成为可能.     

基于折半运算的快速双基数标量乘算法

为了提高椭圆曲线标量乘法效率,对二元域上椭圆曲线的基于双基数的标量乘法进行改进。在底层域推导出直接计算3^kP的快速算法,该算法只需一次求逆;新设计的以1/2和3为基的双基数编码可结合高效的直接计算3^kP和折半运算,基于该双基数编码的标量乘算法只涉及到点加运算、折半运算、三倍点和直接计算3^kP,底层域运算复杂性得到降低,在NIST推荐的椭圆曲线上比Dimitrov算法效率提高70%以上,比Wong方法提高10%以上。     

Conference key agreement protocol with non-interactive fault-tolerance over broadcast network

Most conventional conference key agreement protocols have not been concerned with a practical situation. There may exist some malicious conferees who attempt to block conference initiation for some purposes, e.g. commercial, political or military benefit. Instances where conference must be launched immediately due to emergency, efficient detection of malicious behavior would be needed. Recently, Tzeng (IEEE Trans. Comput. 51(4):373–379, 2002) proposed a fault-tolerant conference key agreement protocol to address the issue where a conference key can be established among conferees even though malicious conferees exist. However, his protocol might be complex and inefficient during fault-detection. In the case where a malicious conferee exists and a fault-tolerant mechanism is launched, complicated interactions between conferees will be required. In this paper, we introduce a novel strategy, where any malicious conferee may be identified and removed from the conferee list without any interaction. With such a non-interactive fault-tolerance, conferences could be established and started efficiently. A complete example of our protocol will be given to describe the fascinating fault-tolerance. We analyse the security of our protocol regarding four aspects, i.e. correctness, fault-tolerance, active attack and passive attack. The comparisons of performance between our protocol and that of Tzeng are also shown. As a whole, the advantage of our protocol is superior to that of Tzeng under the situation where malicious conferees exist.

Efficient processing of spatial joins with DOT-based indexing

A spatial join is a query that searches for a set of object pairs satisfying a given spatial relationship from a database. It is one of the most costly queries, and thus requires an efficient processing algorithm that fully exploits the features of the underlying spatial indexes. In our earlier work, we devised a fairly effective algorithm for processing spatial joins with double transformation (DOT) indexing, which is one of several spatial indexing schemes. However, the algorithm is restricted to only the one-dimensional cases. In this paper, we extend the algorithm for the two-dimensional cases, which are general in Geographic Information Systems (GIS) applications. We first extend DOT to two-dimensional original space. Next, we propose an efficient algorithm for processing range queries using extended DOT. This algorithm employs the quarter division technique and the tri-quarter division technique devised by analyzing the regularity of the space-filling curve used in DOT. This greatly reduces the number of space transformation operations. We then propose a novel spatial join algorithm based on this range query processing algorithm. In processing a spatial join, we determine the access order of disk pages so that we can minimize the number of disk accesses. We show the superiority of the proposed method by extensive experiments using data sets of various distributions and sizes. The experimental results reveal that the proposed method improves the performance of spatial join processing up to three times in comparison with the widely-used R-tree-based spatial join method.     

A Complex View of Barycentric Mappings

Barycentric coordinates are very popular for interpolating data values on polyhedral domains. It has been recently shown that expressing them as complex functions has various advantages when interpolating two‐dimensional data in the plane, and in particular for holomorphic maps. We extend and generalize these results by investigating the complex representation of real‐valued barycentric coordinates, when applied to planar domains. We show how the construction for generating real‐valued barycentric coordinates from a given weight function can be applied to generating complex‐valued coordinates, thus deriving complex expressions for the classical barycentric coordinates: Wachspress, mean value, and discrete harmonic. Furthermore, we show that a complex barycentric map admits the intuitive interpretation as a complex‐weighted combination of edge‐to‐edge similarity transformations, allowing the design of “home‐made” barycentric maps with desirable properties. Thus, using the tools of complex analysis, we provide a methodology for analyzing existing barycentric mappings, as well as designing new ones.     

快速测定化学需氧量的方法

利用分光光度法、微波密封消解法测定水样中的化学需氧量，并把测定的精密度、准确度与国标回流法相比较，结果证明：分光光度法、微波消解法是测定化学需氧量的快捷方法，具有省时、省试剂、工作效率高的特点。