高压下TiSi2可见光光热催化分解水制氢的研究

系统地研究了高压下一系列TiSi2催化剂的可见光光热催化分解水制氢行为.研究结果表明,压力增加显著提高了TiSi2催化剂光催化分解水制氢速率.添加NaOH和Na2CO3有利于水分解制氢的反应进行,在一定范围内,NaOH和Na2CO3浓度增加,放氢速率增加.研究还发现,担载贵金属Pt或Ru对反应速率没有显著影响.本文还采...     

NONLINEAR GALERKIN METHOD FOR NAVIER-STOKES EQUATIONS WITH STREAM-VORTICITY FORM

I Let D be a launder domain in Rz with Lipehitz continuous bodare I'. ac consider the stream-vortidty form of hmedependent Navier-stokes Muahons describing the 'flow Of a ~ incompreSSible nuid confined in Dwhere to and & are vorticity and stream function. BecaUSe the action (1) doeS not include the differentialten z, ~ tie ~ con&tion of' dab at In tthe Paper, we give a ho element n~ Galerkin ~, acs ~ is ~ an tab finite element spaceS X. and X* for the aPPmxhaation of the ~ ac v~ fUncti…     

Numerical analysis of dynamic behavior of stream turbine blade group

This paper considers the stream turbine blade group as a rotationally periodic structure and the complex constraint method has been induced. The effect of the centrifugal force to dynamic vibration frequency has been considered by introducing a nonlinear large deformation equation. A method has been given to introduce the special constraint between the fin heaves of every blade during dynamic analysis.     

两同心旋转球间流动的数值模拟

利用Legendre和伴随Legendre函数来数值模拟定常和不定常的轴对称的同心旋转球间的不可压缩流体的流动.     

Breaking Data Encryption Standard with a Reduced Number of Rounds Using Metaheuristics Differential Cryptanalysis

This article presents the author’s own metaheuristic cryptanalytic attack based on the use of differential cryptanalysis (DC) methods and memetic algorithms (MA) that improve the local search process through simulated annealing (SA). The suggested attack will be verified on a set of ciphertexts generated with the well-known DES (data encryption standard) reduced to six rounds. The aim of the attack is to guess the last encryption subkey, for each of the two characteristics Ω. Knowing the last subkey, it is possible to recreate the complete encryption key and thus decrypt the cryptogram. The suggested approach makes it possible to automatically reject solutions (keys) that represent the worst fitness function, owing to which we are able to significantly reduce the attack search space. The memetic algorithm (MASA) created in such a way will be compared with other metaheuristic techniques suggested in literature, in particular, with the genetic algorithm (NGA) and the classical differential cryptanalysis attack, in terms of consumption of memory and time needed to guess the key. The article also investigated the entropy of MASA and NGA attacks.     

原子荧光光谱法测定土壤、水系沉积物中的碲

对土壤、水系沉积物等地球化学样品中碲的原子荧光光谱测定方法进行了一些改进.方法检出限为0.0081μg/L.对实际样品进行连续12次测定,方法精密度(RSD)为3.55%.     

How Many Bits have to be Changed to Decrease the Linear Complexity?

The k-error linear complexity of periodic binary sequences is defined to be the smallest linear complexity that can be obtained by changing k or fewer bits of the sequence per period. For the period length p ⁿ, where p is an odd prime and 2 is a primitive root modulo p ², we show a relationship between the linear complexity and the minimum value k for which the k-error linear complexity is strictly less than the linear complexity. Moreover, we describe an algorithm to determine the k-error linear complexity of a given p ⁿ-periodic binary sequence.     

Off-line and on-line guaranteed start-up delay for Media-on-Demand with stream merging

We address the problem of designing efficient algorithms for media-on-demand in systems that use stream merging. In the stream merging model the receiving bandwidth of clients is larger than the playback bandwidth, and clients can buffer parts of the transmission to be played back later. Our goal is to minimize the required server bandwidth for a given guaranteed start-up delay and uninterrupted playback. We construct an efficient O(n) optimal off-line algorithm for a time horizon that is composed of n time slots, where the length of one slot is the guaranteed start-up delay. Our algorithm works for either clients with receiving bandwidth twice as much as the playback bandwidth or for receiving bandwidth equal to the server bandwidth, independent of the clients buffer size. We describe an on-line delay guaranteed algorithm that operates without knowledge of the time horizon size, and show that it performs asymptotically close to the optimal off-line algorithm. The on-line algorithm is simpler to implement than previously proposed on-line stream merging algorithms, and empirically performs well when the intensity of client arrivals is high.     

Key-Dependent S-Boxes and Differential Cryptanalysis

Key-dependent S-boxes gained some prominence in block cipher design when Twofish became an AES finalist. In this paper we make some observations on how the cryptanalyst might work with key-dependent S-boxes, we begin to develop a framework for the differential cryptanalysis of key-dependent S-boxes, and we introduce some basic techniques that were used in an analysis of reduced-round Twofish.     

沙漠流场理论分析

为了研究风沙流动所引起的沙漠化问题，本文详细研究了在风的作用下沙漠流场及其基于流体动力学的数学模型建立过程，从沙漠流场的实际性质出发，首先分析了气流场本构方程式的建立过程，然后分析了气流场和沙漠流场的牵连关系和独立性，进一步深入地分析了沙漠流场及其本构方程式的建立过程，最后给出了气流场影响下的沙漠流场的数学模型，为今后的数值分析提供了理论基础。