RANDOM NUMBER GENERATOR

The requirements, design principles, and statistical testing approaches of uniform random number generators for simulation are briefly surveyed. An object-oriented random number package where random number streams can be created at will, and with convenient tools for manipulating the streams, is presented. A version of this package is now implemented in the Arena and AutoMod simulation tools. We also test

Le but de cette étude était d'examiner l'effet d'un programme d'activités physiques sur la stabilité et le contrôle attentionnel de la posture lors de la réalisation concomitante d'une tâche cognitive attentionnelle chez des personnes âgées en perte d'autonomie.Douze personnes âgées (M = 81,4 ± 9 ans), institutionnalisées en structure gériatrique ont participé à un programme d'activités physiques de type posture–équilibration–motricité (PEM) pendant 12 semaines à raison de deux séances d'une heure par semaine. Les paramètres stabilométriques de surface et de longueur du trajet parcouru par le centre de pression plantaire (CPP), les yeux ouverts (YO) et les yeux fermés (YF), en condition simple-tâche et en condition double-tâche sur sol dur ont été analysés avant et après le programme d'entraînement. En condition double-tâche, les sujets effectuaient, lors de l'évaluation stabilométrique, une tâche cognitive attentionnelle de génération de chiffres aléatoires.Les principaux résultats ont révélé que seule la longueur du trajet parcouru par le CPP était plus importante en condition double-tâche qu'en condition simple-tâche (p = 0,05). Lors de l'évaluation initiale, la performance à la tâche cognitive était significativement moins bonne en condition double-tâche (debout) qu'en condition simple-tâche (assis), seulement dans la modalité YF mais pas dans la modalité YO (p < 0,05). Toutefois, à l'issue du programme d'entraînement, les performances à la tâche cognitive ne se différenciaient plus (n.s.) pour les deux conditions assis YF et debout YF.L'entraînement a permis d'améliorer la capacité des sujets à réaliser une tâche mentale attentionnelle tout en maintenant un équilibre correct, notamment les yeux fermés. Bien que les performances stabilométriques semblaient moins bonnes en condition double-tâche qu'en condition simple-tâche, ces résultats pourraient être interprétés comme une amélioration, suite au programme d'entraînement, du contrôle attentionnel du maintien de la posture. Les limites méthodologiques de cette étude sont ensuite discutées.We aimed to examine the effect of a physical activity program on postural sway and on the attentional control of postural abilities in elderly frail adults.Twelve older adults (age 81.4 ± 9 years) institutionalised in a geriatric care institution participated in the physical activity program posture–balance–mobility (PBM) twice a week (1 hour per session) for 12 weeks. We analysed stabilometric data for surface and length of the center of pressure (COP) sway, with eyes open and eyes closed, under single-task and dual-task conditions on a firm floor before and after the training program. During the static postural evaluation and under the dual-task condition, subjects performed an attention-demanding cognitive task, the random number generation task.Only the length of COP sway was more important under the dual-task condition than under the single-task condition (p = 0.05). At baseline, cognitive performance was significantly weaker under the dual-task condition (standing) than under the single-task condition (seated), with eyes closed but not eyes open (p < 0.05). However, after the training program, the performance of the cognitive task did not significantly differ between the dual-task condition with eyes closed and the single-task condition with eyes closed.The training program allowed elderly subjects to improve their ability to perform an attention-demanding cognitive task while standing still, in particular with their eyes closed. Although balance seemed to be less stable under the dual-task condition than under the single-task condition, these results could be interpreted as an improvement of the attentional control of postural stability.

Abstract. This paper discusses the testing of methods for generating uniform mlml)crs in a computer--the commonly used multiplicative and mixed congruential generators as well ks two new methods. Tests proposed here are more stringent than those usually applied, ...

Subsidence analysis based on decompaction of the sedimentary record is a standard method for reconstructing the evolution of sedimentary basins. For such an analysis, data on strata thickness, lithology, age constraints, lithological properties, porosity, palaeobathymetry, ...

Random numbers are used in a wide variety of applications from simulation and encryption to gambling and clinical trials. A good quality random number generator is an asset for applications like encryption, randomized designs and network and information security. Various mathematical models have been developed in the past to improve the quality of random numbers. It can be construed that in general to obtain random numbers of excellent quality, a complex mathematical model has to be used which can be a performance bottleneck. In this work, we propose a novel technique to implement a True Random Number Generator (TRNG) using sources of uncertainty found within Graphics Processing Units (GPUs) together with histogram equalization to obtain maximum entropy. We evaluate the random numbers generated by our approach using four tests. First, we measure the correlation values between two sequences of random numbers, second, we measure the entropy values, third, we use watermarking, an application used in network security and finally we use Monte Carlo analysis for pi-value calculation. Based on these quality measurements, our method has achieved better results than popular random number generators compared in this work. Furthermore, this approach is a massively scalable solution ideal for high performance computing implementations.

Advanced bit manipulation operations are not efficiently supported by commodity word-oriented microprocessors. Programming tricks are typically devised to shorten the long sequence of instructions needed to emulate these complicated bit operations. As these bit manipulation operations are relevant to applications that are becoming increasingly important, we propose direct support for them in microprocessors. In particular, we propose fast bit gather (or parallel extract), bit scatter (or parallel deposit) and bit permutation instructions (including group, butterfly and inverse butterfly). We show that all these instructions can be implemented efficiently using both the fast butterfly and inverse butterfly network datapaths. Specifically, we show that parallel deposit can be mapped onto a butterfly circuit and parallel extract can be mapped onto an inverse butterfly circuit. We define static, dynamic and loop invariant versions of the instructions, with static versions utilizing a much simpler functional unit. We show how a hardware decoder can be implemented for the dynamic and loop-invariant versions to generate, dynamically, the control signals for the butterfly and inverse butterfly datapaths. The simplest functional unit we propose is smaller and faster than an ALU. We also show that these instructions yield significant speedups over a basic RISC architecture for a variety of different application kernels taken from applications domains including bioinformatics, steganography, coding, compression and random number generation.

Nowadays, there are many new methods for slope stability analysis; including probabilistic methods assessing geotechnical uncertainties to develop safety factors. In this paper, a reliability index analysis for the Sungun copper mine slope stability is evaluated based on three methods of uncertainties consisting Taylor series method, Rosenblueth point estimate method and Monte-Carlo simulation method. Sungun copper mine will be one of the Iran’s biggest mines with final pit’s height of 700 meters. For this study two of its main slopes were assessed, one dipping to the NE (030) and the other to the SE (140). Probability density function of cohesion and angle of friction for the slopes were developed using limit equilibrium methods. These shear strengths were then used to determine the probability density function of safety factor and reliability index using the probabilistic methods. Results of the probabilistic analysis indicate that with ascending values of the uncertainties the reliability index decreases. Furthermore, it was determined that with the Monte Carlo simulation the seed number used has little effect on the reliability index of the safety factor especially with seed numbers in excess of 1200. Variations in the overall reliability index of safety factor were observed between the two slopes and this difference is explained by the differences in complexities of the geology within the cross-section.