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11.
Identity management is based on the creation and management of user identities for granting access to the cloud resources based on the user attributes. The cloud identity and access management (IAM) grants the authorization to the end-users to perform different actions on the specified cloud resources. The authorizations in the IAM are grouped into roles instead of granting them directly to the end-users. Due to the multiplicity of cloud locations where data resides and due to the lack of a centralized user authority for granting or denying cloud user requests, there must be several security strategies and models to overcome these issues. Another major concern in IAM services is the excessive or the lack of access level to different users with previously granted authorizations. This paper proposes a comprehensive review of security services and threats. Based on the presented services and threats, advanced frameworks for IAM that provide authentication mechanisms in public and private cloud platforms. A threat model has been applied to validate the proposed authentication frameworks with different security threats. The proposed models proved high efficiency in protecting cloud platforms from insider attacks, single sign-on failure, brute force attacks, denial of service, user privacy threats, and data privacy threats. 相似文献
12.
The problem of an elastic beam under the periodic loading of successive moving masses is investigated as a pragmatic case for studying dynamic stability of linear time-varying systems. This model serves to highlight the odds of multi-solutions coexistence, a form of hidden instability which reveals dangerous as it may be precipitated by the slightest disturbance or variation in the model. Since no engineering model perfectly represents a physical system, such situations for which Floquet theory naively predicts stability are potentially inevitable. The harmonic balancing method is used in order to thoroughly explore the stability diagrams for detecting these instability gaps. Although this phenomenon has also been described in other physical systems, it has not been addressed for beam–moving mass systems. This result may find particular importance in applications involving self-induced vibrations of elastic structures and hence also appears of practical relevance. 相似文献
13.
Glenn A. A. Thuwis Roeland De Breuker Mostafa M. Abdalla Zafer Gürdal 《Structural and Multidisciplinary Optimization》2010,41(4):637-646
The aim of the present work is to passively reduce the induced drag of the rear wing of a Formula One car at high velocity
through aeroelastic tailoring. The angle-of-attack of the rear wing is fixed and is determined by the required downforce needed
to get around a turn. As a result, at higher velocity, the amount of downforce and related induced drag increases. The maximum
speed on a straight part is thus reduced due to the increase in induced drag. A fibre reinforced composite torsion box with
extension-shear coupled upper and lower skins is used leading to bending-torsion coupling. Three-dimensional static aeroelastic
analysis is performed loosely coupling the Finite Element code Nastran and the Computational Fluid Dynamics panel code VSAERO
using ModelCenter. A wing representative of Formula One rear wings is optimised for minimum induced drag using a response
surface methodology. Results indicate that a substantial induced drag reduction is achievable while maintaining the desired
downforce during low speed turns. 相似文献
14.
Mostafa I. SolimanAuthor Vitae Ghada Y. AbozaidAuthor Vitae 《Journal of Parallel and Distributed Computing》2011,71(8):1075-1084
This paper describes the FPGA implementation of FastCrypto, which extends a general-purpose processor with a crypto coprocessor for encrypting/decrypting data. Moreover, it studies the trade-offs between FastCrypto performance and design parameters, including the number of stages per round, the number of parallel Advance Encryption Standard (AES) pipelines, and the size of the queues. Besides, it shows the effect of memory latency on the FastCrypto performance. FastCrypto is implemented with VHDL programming language on Xilinx Virtex V FPGA. A throughput of 222 Gb/s at 444 MHz can be achieved on four parallel AES pipelines. To reduce the power consumption, the frequency of four parallel AES pipelines is reduced to 100 MHz while the other components are running at 400 MHz. In this case, our results show a FastCrypto performance of 61.725 bits per clock cycle (b/cc) when 128-bit single-port L2 cache memory is used. However, increasing the memory bus width to 256-bit or using 128-bit dual-port memory, improves the performance to 112.5 b/cc (45 Gb/s at 400 MHz), which represents 88% of the ideal performance (128 b/cc). 相似文献
15.
In this paper, a new homotopy perturbation method (NHPM) is introduced for obtaining solutions of systems of non-linear partial differential equations. Theoretical considerations are discussed. To illustrate the capability and reliability of the method three examples are provided. Comparison of the results of applying NHPM with those of applying HPM reveal the effectiveness and convenience of the new technique. 相似文献
16.
Mostafa Sabzekar Hadi Sadoghi Yazdi Mahmoud Naghibzadeh 《Neural computing & applications》2011,20(5):671-685
Real-world data collected for computer-based applications are frequently impure. Differentiation of outliers and noisy data
from normal ones is a major task in data mining applications. On the other hand, elimination of noisy and outlier data from
training samples of a dataset may lead to over-fitting or information loss. A fuzzy support vector machine (FSVM) provides
an effective means to deal with this problem. It reduces the effect of the noisy data and outliers by using a fuzzy membership
functions. In this paper, a new formation for SVMs is introduced that considers importance degrees for training samples. The
constraints of the SVM are converted to fuzzy inequalities. The proposed method, RSVM, shows better efficiency in the classification
of data in different domains. Especially, using the proposed RSVM for multi-class classification of arrhythmia disease is
presented at the end of this paper as a practical case study to show the effectiveness of the proposed system. 相似文献
17.
Mostafa I. Yacoub Dan S. Necsulescu Jurek Z. Sasiadek 《Journal of Intelligent and Robotic Systems》2016,83(3-4):585-602
Operation of mobile robots in off-road environment requires the attention to the torque saturation problem that occurs in the wheels DC motors while climbing hills. In the present work, off-road conditions are utilized to benefit while avoiding torque saturation. Energy optimization algorithm using predictive control is implemented on a two-DC motor-driven wheels mobile robot while crossing a ditch. The predictive control algorithm is simulated and compared with the PID control and the open-loop control. Predictive control showed more capability to avoid torque saturation and noticeable reduction in the energy consumption. Furthermore, using the wheels motors armature current instead of the supply voltage as control variable in the predictive control showed more efficient speed control. Simulation results showed that in case of known ditch dimensions ahead of time, the developed algorithm is feasible. Experimental examination of the developed energy optimization algorithm is presented. The experimental results showed a good agreement with the simulation results. The effects of the road slope and the prediction horizon length on the consumed energy are evaluated. The analytical study showed that the energy consumption is reduced by increasing the prediction horizon until it reaches a limit at which no more energy reduction is obtained. This limit is proportional to the width of the ditch in front of the mobile robot. Curve fitting is applied to the obtained results to address further the effect of the parameters on the energy consumption. 相似文献
18.
Zarefard Mostafa Effati Sohrab 《International Journal of Control, Automation and Systems》2017,15(4):1877-1887
International Journal of Control, Automation and Systems - In this paper, the synchronization of two non-identical bidirectional associative memory (BAM) neural networks with unknown parameters and... 相似文献
19.
Amin Manouchehrian Mostafa Sharifzadeh Rasoul Hamidzadeh Moghadam Tohid Nouri 《矿业科学技术学报(英文版)》2013,23(4):495-501
Recently, many regression models have been presented for prediction of mechanical parameters of rocks regarding to rock index properties. Although statistical analysis is a common method for developing regression models, but still selection of suitable transformation of the independent variables in a regression model is difficult. In this paper, a genetic algorithm (GA) has been employed as a heuristic search method for selection of best transformation of the independent variables (some index properties of rocks) in regression models for prediction of uniaxial compressive strength (UCS) and modulus of elasticity (E). Firstly, multiple linear regression (MLR) analysis was performed on a data set to establish predictive models. Then, two GA models were developed in which root mean squared error (RMSE) was defined as fitness function. Results have shown that GA models are more precise than MLR models and are able to explain the relation between the intrinsic strength/elasticity properties and index properties of rocks by simple formulation and accepted accuracy. 相似文献
20.
Beroz J Bedewy M Reinker M Chhajer V Awtar S Hart AJ 《The Review of scientific instruments》2012,83(1):015104
Capillary forces provide a ubiquitous means of organizing micro- and nanoscale structures on substrates. In order to investigate the mechanism of capillary self-assembly and to fabricate complex ordered structures, precise control of the meniscus shape is needed. We present a precision instrument that enables deposition of liquid droplets spanning from 2 nl to 300 μl, in concert with mechanical manipulation of the liquid-substrate interface with four degrees of freedom. The substrate has sub-100 nm positioning resolution in three axes of translation, and its temperature is controlled using thermoelectric modules. The capillary tip can rotate about the vertical axis while simultaneously dispensing liquid onto the substrate. Liquid is displaced using a custom bidirectional diaphragm pump, in which an elastic membrane is hydraulically actuated by a stainless steel syringe. The syringe is driven by a piezoelectric actuator, enabling nanoliter volume and rate control. A quantitative model of the liquid dispenser is verified experimentally, and suggests that compressibility in the hydraulic line deamplifies the syringe stroke, enabling sub-nanoliter resolution control of liquid displacement at the capillary tip. We use this system to contact-print water and oil droplets by mechanical manipulation of a liquid bridge between the capillary and the substrate. Finally, we study the effect of droplet volume and substrate temperature on the evaporative self-assembly of monodisperse polymer microspheres from sessile droplets, and demonstrate the formation of 3D chiral assemblies of micro-rods by rotation of the capillary tip during evaporative assembly. 相似文献