用爬山法实现无中心式网格调度

为方便网格资源的扩展,网格调度应当是无中心的.为在尽可能多的计算资源中为单地点作业优化资源选择,这里采用了爬山算法.当一个网格调度器收到一个单地点作业,爬山法被激活,根据网格调度器之间的相邻关系为作业找出最适合的计算系统,这里每个计算系统的适合度用预测的作业响应时间表示.实验模拟了无中心式网格调度与计算系统之间的性能差别,每个计算系统的本地调度采用保守式装填法,网格工作负荷由模型得到,并用一段工作负荷的平均响应时间衡量调度性能.实验结果表明,即使在作业提交点分布不均匀且运行时间估计不准确情况下,爬山法仍可有效改善单地点作业的调度.     

FINDING VOWELS IN SIMPLE SUBSTITUTIONS CIPHERS BY COMPUTER

Abstract

The Faculty of Mathematics and Computer Science of Adam Mickiewicz University established an annual series of lectures in computer science. The series is named after Marian Rejewski, Jerzy Ró?ycki, and Henryk Zygalski, alumni of the University who played a key role in the Enigma cipher machine breaking. The inaugural lectures were given by Marek Grajek, Adrew Odlyzko, and Józef Pieprzyk on Cryptology Day, January 25th, 2008.     

基于组合式爬山算法提高S盒非线性度的方法

针对三点和四点爬山算法对随机置换盒(S盒)的非线性度进行优化时计算量大及效率低的问题,提出了一种组合式爬山算法(CHC)。该算法把交换S盒两个输出数据的行为定义为一个交换元,利用加权择优函数,筛选出若干个对非线性度的提升贡献较大的交换元,然后通过同时应用多个交换元,达成提高S盒非线性度的目标。实验中利用CHC算法,一次最多交换了12个输出数据,使得大部分8输入8输出随机S盒的非线性度超过了102,最高可达106。实验结果表明,所提出的CHC算法相比于三点和四点爬山算法,不仅降低了计算量,而且对随机S盒的非线性度也有着更为明显的提升作用。     

基于爬山粒子群优化的移动传感网络定位算法

针对蒙特卡洛定位（Monte Carlo Localization,MCL）采样效率不高,定位精度较低的问题,提出一种新的基于爬山法优化策略的移动无线传感网络定位算法HCPSO-MCL（Hill Climbing Particle Swarm Optimization-MCL）,将节点定位问题转化为全局优化问题。HCPSO-MCL算法采用基于爬山策略的混合粒子群优化算法对MCL的估计值进行修正,从而实现节点快速准确定位。实验仿真结果表明,HCPSO-MCL较之于MCL算法在定位精度上有很大改进,而且比PSO-MCL（Particle Swarm Optimization-MCL）算法有更快的收敛性。     

Cryptanalysis of columnar transposition cipher with long keys

The classical columnar transposition cipher was the most popular type of transposition cipher. It was in use mainly during the second half of the nineteenth century and the first half of the twentieth century. It also served as a building block for more complex ciphers, such as the ADFGVX cipher and the double transposition cipher. Pen-and-paper as well as computerized methods for the cryptanalysis of the columnar transposition cipher have been published, but those apply mainly to the easier cases of short keys and complete transposition rectangles. In this article, a novel approach for the cryptanalysis of the columnar transposition cipher (when used with long keys) is presented. It is based on a two-phase hill climbing algorithm, a two-dimensional fitness score, and special transformations on key segments. This ciphertext-only method allows for the recovery of transposition keys with up to 1,000 elements, and up to 120 elements for worst case transposition rectangles.     

THE POLISH ENIGMA CONFERENCE AND SOME EXCURSIONS

The city of Bydgoszcz, Poland, held a conference on Enigma in honor of Marian Rejewski, one of the 1932 solvers of that cipher machine who was born and brought up in that industrial city. I then visited several sites in Poland connected with cryptology.     

Spanish Enigma: A History of the Enigma in Spain

Abstract

The presentation of a brief study of the use of Enigma Machines in Spain, during the Spanish Civil War (1936–1939) and later, until their final replacement.     

爬山算法对一阶相关免疫函数非线性度的优化研究

在布尔函数的设计中,总是希望得到满足多个密码特性的密码函数,但是这些密码特性之间存在着一定的制约关系。利用爬山算法对一阶相关免疫函数进行了优化,得到了大量高非线性度的布尔函数并通过MATLAB 实验对八元、九元一阶相关免疫函数进行了优化。实验结果表明,该算法可进一步优化相关免疫函数的非线性度。     

Autonomous legged hill ascent

This paper reports on an autonomous ascent by a legged robotic platform in outdoor forested terrain. Two controllers govern the integration of online inertial measurement unit and light detection and ranging sensor signals into commands for climbing by means of an abstracted (unicycle) representation of the platform in support of different performance goals: a kinematic version for endurance and a dynamic version for speed. These control laws, backed by a suite of formal correctness guarantees, encourage a stripped‐down sensory suite supporting a simplified world model whose departures from the actual physical environment are handled by the mechanical competence of the legged platform. Both behaviors are implemented on a version of the legged RHex platform, and experiments spanning almost a kilometer (thousands of body lengths) in various challenging settings are conducted.     

REVIEW OF THINGS CRYPTOLOGIC

Abstract

Sets out, with comments, an account by A. G. Denniston (the operational head of the British Government Code and Cypher School in 1939) of the meeting near Pyry, Poland, in July 1939, when Polish cryptanalysts revealed how they broke Enigma, and a letter by Dillwyn Knox on the meeting's outcome.     

History and Modern Cryptanalysis of Enigma's Pluggable Reflector

The development history of Umkehrwalze Dora, Enigma's pluggable reflector, is presented from the first ideas in the mid-1920s to the last development plans and its actual usage in 1945. An Enigma message in three parts, enciphered with Umkehrwalze Dora and intercepted by the British on 11 March 1945, is shown. The successful recovery of the key of this message is described. Modern computer-based cryptanalysis is used to recover the wiring of the unknown “Uncle Dick,” which the British called this field-rewirable reflector. The attack is based on the known ciphertext and plaintext pair from the first part of the intercept. After recovery of the unknown reflector wiring and the daily key, the plaintext of the second part of the message is revealed.     

Gait optimization of step climbing for a hexapod robot

RHex-style hexapod robot is a type of legged robot which can perform multiple moving gaits according to different applications, due to its simple structure and strong mobility. However, traversing high obstacles has always been a big challenge for legged robots. In this paper, gait optimization of a hexapod robot is proposed for climbing steps at different heights, which even enables the robot to climb the step 3.9 times of the leg length. First, a previous step-climbing gait is optimized by adjusting body inclination when placing front legs on top of the step, which enables RHex with different sizes to perform the rising stage of the gait. Second, to improve the climbing heights, a novel quasi-static climbing gait is proposed by using the reversed claw-shape legs to reach the higher step. The nondeformable legs are used to raise the center of mass (COM) of the body by lifting the front and rear legs alternately so that the front legs can reach the top of the step, then the front and middle legs are lifted alternately to maneuver COM up onto the step. The simulations and dynamic analysis of climbing steps are utilized to verify the feasibility of the improved gait. Finally, the step-climbing experiments at different heights are performed with the optimized gaits to compare with the existing gaits. The results of simulations and experiments show the superiority of the proposed gaits due to climbing higher steps.     

Study on climbing strategy and analysis of Mars rover

To ensure the safety and efficiency of Zhurong Mars rover when climbing a slope on Mars, the forces of the rover under four climbing methods, which are normal climbing, Z-type climbing, diagonal climbing, and bionic wriggle climbing, are analyzed. Each method corresponds to different maximum climbing slopes. The experiments are carried out with a backup rover on dense and soft terrains to determine the range of climbing slope for different climbing methods. According to the slope, peak current, cost of transport, and state of terrain, the climbing strategy is given. For dense and soft terrains, the soil cohesive is 0.99 and 1.4 kN/mⁿ⁺¹ and soil friction modules are 1528 and 700 kN/mⁿ⁺², respectively. Specifically, normal climbing is recommended for low-range slopes, while Z-type or diagonal climbing are suggested for medium-range slopes, and bionic wriggle climbing is found to be optimal for high-range slopes. To ensure the safety of the Zhurong Mars rover, it fails climbing if the critical values are exceeded. These results provide valuable insights for human operators when planning the rover's slope-climbing actions on Mars.     

Modern breaking of Enigma ciphertexts

“Breaking German Army Ciphers” is the title of a Cryptologia article from 2005, describing the lucky survival of several hundred authentic Enigma messages of World War II, and an account of a ciphertext-only cryptanalysis of a large number of these messages, leaving only a few (mostly short messages) unbroken. After reviewing the work done, and investigating the reasons for both lucky breaks and close misses, the modern ciphertext-only attack on Enigma messages is improved, especially on genuine ones with short lengths and/or many garbles. The difficulties of a proper measure for the candidate’s closeness to a plaintext are clarified. The influence on the decryption process of an empty plugboard and one with only a few correct plugs is examined. The method is extended by a partial exhaustion of the plugboard combined with an optimized hillclimbing strategy. The newly designed software succeeds in breaking formerly unbroken messages.     

OmniClimbers: Omni-directional magnetic wheeled climbing robots for inspection of ferromagnetic structures

This paper introduces Omniclimber, a new climbing robot with high maneuverability for inspection of ferromagnetic flat and convex human made structures. In addition to maneuverability, adaptability to various structures with different curvatures and materials are addressed. The conceptual and detailed design of OmniClimbers are presented and two prototypes of the robot are introduced. Several laboratory and field tests are reported, and the results are discussed.     

Ride sharing with flexible participants: a metaheuristic approach for large‐scale problems

Severe traffic congestion and growing ecological consciousness have led to the rise of alternative transportation systems. Ride sharing is one such alternative in which drivers and passengers with similar time schedules and travel plans are matched. For this service to be effective, a large number of users are required to increase the probability of finding suitable travel partners. The present paper proposes a late acceptance metaheuristic to decide which users act as drivers and to construct their routes. The underlying optimization model allows passengers to walk to/from alternative pickup/drop‐off locations so as to further exploit user flexibility. A computational study quantifies the impact of different types of participant flexibility on CO₂ emissions. These insights can inform and support policymakers in organizing effective ride‐sharing systems.     

Prediction of slip resistance in climbing systems

The objective of this study was to develop a predictive model describing the slip resistance of various climbing surfaces. In a four-factor experiment, seven commonly used metal grating step surfaces were evaluated, along with four types of shoe soles (crepe, leather, ribbed-rubber, and oil-resistant-rubber); three contaminant conditions (dry, wet-water, and diesel fuel); and direction of force application. The results showed that the available slip resistance coefficients (ASRC) varied primarily as a function of sole material and contaminants. This result and the significant interactions between sole and step surfaces suggest that the appropriate selection of shoe soles and control of contaminants may be the most effective way of attaining adequate ASRC values. A predictive equation was developed using multiple regression which described the evaluated conditions with binary indicator variables. To increase the equation's applicability, the step surfaces were described in terms of generic features such as: painted vs. bare metal surface; ring vs. point protrusions; edge orientation; contact area, and protrusion height gradient. The equation explained 89% of the variance in the original data. In a validation study, the equation explained 80% of the variance in slip resistance for a new step surface under the original set of sole, contaminant, and directionality conditions.     

EJBot-II: an optimized skid-steering propeller-type climbing robot with transition mechanism

This paper presents a new kind of climbing robots called EJBot, which has not been restricted to climb certain surface materials or terrains. EJBot is inspired by propeller-based aviation systems, however, its adhesion principle is opposite to flight concept. Thanks to the hybrid actuation system embedded in this robot which gives a good and stable adhesion. This hybrid system consists of propeller thrust forces and wheel torques actuated simultaneously to generate the proper adhesion force. It is similar to a car climbing a ramp, it needs both weight of the car and the wheels' torques. Without these torques, the car will roll down. Consequently, the thrust forces of the propellers increase the traction force capacity, then the wheels' role arises to generate the convenient torques for stopping the robot or navigating it on the structures. The feasibility of this adhesion concept is verified by the first and second modules of EJBot as presented in the simulation and practical results.     

差分演化优化Ncut准则的彩色图像分割

针对解Ncut准则的SM算法寻优能力不足的问题,提出一种基于差分演化优化归一化准则的彩色图像分割算法。首先对彩色图像进行爬山法预分割为多类,并构造类级间的无向完全图,之后再使用二进制差分演化算法求得Ncut准则最小化的图二分,最后通过映射获得图像的二值分割。实验结果表明,在相同预处理情况下,本文的寻优算法与SM算法相比,分割效果更为精准。     

多传感器数据融合在爬架控制系统中的应用

针对传统爬架控制系统存在安全性评估不全面、报警准确率低的缺陷,提出了一种基于多传感器数据融合技术以提高爬架控制系统安全预警性能的方法.该方法通过传感器采集爬架载荷、倾斜角度和爬升速度等数据,利用BP神经网络对数据进行融合,并对系统的安全性能做出评估.详细介绍了融合算法、训练过程、系统硬件构成和软件实现.测试结果表明:该方法不仅能多角度评估系统的安全性,而且能提高爬架控制系统报警准确性,从而提高爬架系统的可靠性.