Outage Probability Analysis of Cooperative Diversity Networks Over Weibull and Weibull-Lognormal Channels

This paper presents the analysis of outage probability for a cooperative diversity wireless network using amplify-and-forward relays over independent non-identical distributed Weibull and Weibull-lognormal fading channels for single as well as multiple relays. To reach that end, a closed-from expression for the moment-generating function of the total signal-to-noise-ratio (SNR) at the destination is derived in terms of the tabulated Meijer’s G-function. Since it is hard to determine the exact probability distribution function of the SNR, a tight lower bound approximation is proposed. Simulation results are presented that show that the outage probability lower bound tends to be tight at high SNR values thus verifying the analytical results. The results also show the potential gain of relaying on the outage probability.     

Modeling of filtration through multiple layers of dual scale fibrous porous media

Functionally graded composites exhibit properties within the material that vary gradually without a recognizable boundary. One technique to manufacture functionally graded polymer composites is by liquid composite molding process. In this process, structural fabric layers are stacked in a closed mold and resin is injected into the mold. Particles may be added to the resin to tailor the properties of the final product. The structural fabrics typically consist of yarns or bundles of thousands of micron size fibers woven, stitched, or knitted together, which gives rise to a bimodal distribution of pore sizes; the larger pores in between the bundles and smaller ones within the bundles. The filtration process that takes place during infusion alters the flow resistance of the porous media and complicates the impregnation process. In this study, a vacuum‐assisted resin transfer molding (VARTM) process‐based approach is presented that enables functional grading in composites to obtain a desired distribution in properties. A model of the filtration phenomenon is proposed to predict the concentration distribution of particles within the dual scale fibrous porous media infused under a constant pressure drop. The approach uses Darcy's law and accounts for lowering of the permeability value due to the particle entrapment in the available pores. Experiments are conducted and the concentration of the particles in the fabric is measured. The results compare well with the predictions despite many assumptions made in the model. Nondimensional analysis and parametric study reveals the influence of critical parameters on the final particles concentration gradient. POLYM. COMPOS. 27:570–581, 2006. © 2006 Society of Plastics Engineers     

Ambiguity attacks on SVD audio watermarking approach using chaotic encrypted images

In this paper, we study the robustness of the proposed watermarking algorithm by Al-Nuaimy et al. (Digit Signal Process 21(6):764–779 2011) for audio signals which is based on singular value decomposition (SVD). It has been concluded that it is fundamentally flawed in its design, in that it falls to two ambiguity attacks where the extracted watermark is not the embedded one but determined by the reference watermark. In the first attack, when a watermarked audio signal is rewatermarked by an attacker’s watermark, this one can be easily extracted to claim ownership of the original audio signal. In the second attack, during the extracting process when an attacker uses the singular vectors of his watermark, he can extract the attacker’s watermark. Therefore, he can claim ownership of the watermarked audio signal. The experimental results prove that the proposed attacks create a false positive detection in watermark extraction. Therefore, Al-Nuaimy et al. algorithm cannot be used for security systems, data hiding and copyright protection.

     

MODE I AND MIXED-MODE STABLE CRACK EXTENSIONS THROUGH STIFFENED THREE-POINT BEND SPECIMENS

Abstract Both experimental and theoretical results on stable crack extensions are presented for symmetrically stiffened and unstiffened three point bend specimens subjected to mode I or mixed mode loading systems. Results concerning load-displacement variation, growth of plastic zones, instantaneous crack edge profiles, tunnelling, etc., are presented. There is good agreement between the experimental and theoretical results. The whole of stable crack growth can be characterized by the crack opening angle criterion. The stiffening helps to increase substantially both the initiation load and the maximum fracture load.     

Lack of association between renin-angiotensin system, gene polymorphisms, and wall thickness of the radial and carotid arteries

To investigate the relationship between polymorphisms of the angiotensin-converting enzyme (ACE) and the angiotensin II type 1 receptor (AT1R) genes and structural phenotypes of arteries, we studied a cohort of 340 subjects (aged 49+/-12 years) without evidence of cardiovascular disease and who had never been treated previously with any cardiovascular treatments. Structural phenotypes (wall thickness and internal diameter) were evaluated for the common carotid and the radial arteries using high-resolution echo-tracking devices (NIUS-02 and Wall Track System). The influence of ACE insertion/deletion (I/D) and AT1R A/C1166 polymorphism genotypes on structural parameters was tested by ANOVA and logistic regression analysis. For the radial artery, mean wall thickness among subjects according to the ACE I/D or AT1R A/C1166 genotypes was not different. This lack of association persisted in a logistic regression analysis or when the comparison was restricted to a subgroup of subjects potentially at high genetic risk (DD and CC or AC) compared with subjects at low genetic risk (AA and II or ID). Also, no association was observed between the carotid artery intima-media thickness and the 2 polymorphisms. In conclusion, the ACE I/D and the AT1R A/C1166 gene polymorphisms are not markers of vascular hypertrophy in subjects with no evidence of cardiovascular disease. These results suggest that these gene polymorphisms have an undetectable role in the geometry of the radial and carotid arteries compared with usual determinants such as blood pressure and age.     

Balancing of an inverted pendulum with a SCARA robot

The balancing act of an inverted pendulum with a robotic manipulator is a classical benchmark for testing modern control strategies in conjunction with fast sensor-guided movements. From the control design perspective, it presents a challenging and difficult problem, as the system is open-loop instable and includes nonlinear effects in the actuators, such as friction, backlash, and elasticity. In addition, the necessity of a sensor system that can measure the inclination angles of the pendulum contributes to the complexity of the balancing problem. The pendulum is projected onto the xz and yz planes of the inertial coordinate system. These projections are treated independently from each other and are controlled individually by a state-space controller in the x and y axes, respectively. The nonlinearities of the robot are compensated by using inverse dynamics and inverse kinematics. A specially developed sensor system allows the contactless measurement of the inclination angles of the pendulum. This system consists of a small magnet, placed at the bottom of the pendulum, and Hall-effect sensors placed inside the end effector     

Some notes on fusion of uncertain information

This article attempts to analyze the combination of uncertain pieces of information, particularly, given several pieces of information, each of which is assigned a certainty factor. The problem then is whether it is possible to find the certainty factor associated with the combination result. This problem, even if it has been widely commented on in probability literature from various viewpoints, sounds less analyzed in the framework of possibility or evidence theories. This study investigates various proposals for quantifying certainty qualification and then constructs the certainty assigned for the combination result of initial inputs. First, we shall consider some basic combination modes and then attempt to generalize the result for more general combination modes. © 2004 Wiley Periodicals, Inc.     

Query Processing and Optimization on the Web

The advent of the Internet and the Web and their subsequent ubiquity have brought forth opportunities to connect information sources across all types of boundaries (local, regional, organizational, etc.). Examples of such information sources include databases, XML documents, and other unstructured sources. Uniformly querying those information sources has been extensively investigated. A major challenge relates to query optimization. Indeed, querying multiple information sources scattered on the Web raises several barriers for achieving efficiency. This is due to the characteristics of Web information sources that include volatility, heterogeneity, and autonomy. Those characteristics impede a straightforward application of classical query optimization techniques. They add new dimensions to the optimization problem such as the choice of objective function, selection of relevant information sources, limited query capabilities, and unpredictable events. In this paper, we survey the current research on fundamental problems to efficiently process queries over Web data integration systems. We also outline a classification for optimization techniques and a framework for evaluating them.