Efficient cluster head selection using Naïve Bayes classifier for wireless sensor networks

Data mining and approaches based on it have always been of approaches that have been considered in solving problems in the field of computer, but on some issues, this approach has been neglected. The area of wireless sensor networks and specifically the issue of optimal determining of the cluster head node are of these issues. To solve the problem of optimal determining of the cluster head node, Naïve Bayes that is the subset of data mining techniques is used in this paper. The results obtained after simulation of the presented algorithm show that the efficiency of this algorithm is significantly higher compared with other approaches that have so far been used to solve this problem, and thus it can be said that using this algorithm will lead to improved outcomes of solving this problem.     

Investigation of the effect of temperature and layup on the press forming of polyvinyl chloride-based composite laminates and fiber metal laminates

Semi-crystalline thermoplastic-based composite laminates and fiber metal laminates have a narrow forming temperature window, which limits formability of these products. The intention of this study was investigation of non-melting amorphous polyvinyl chloride as a proper matrix to increase the formability and forming temperature window of these products. For this, [45/?45] and [0/90] layups of polyvinyl chloride-based composite laminates and fiber metal laminates were produced using the film-stacking procedure and later press formed into channel sections at six temperatures in the range of 80 to 200 °C. The effects of the layups and forming temperatures on the forming loads and spring back of the formed profiles were measured, and their effects on the fiber buckling, wrinkling, and delamination of the profiles were evaluated using optical microscope images. The effects of layups and forming temperatures on the deformation mechanisms were also analyzed using the grid strain analysis method. Of the fiber metal laminates, 160 °C was found as the minimum forming temperature, and for the composite laminates, 120 and 160 °C were found as the minimum proper forming temperatures of [45/?45] and [0/90] layups, respectively. Finally, the forming temperature windows and formability of polyvinyl chloride matrix composite laminates and fiber metal laminates were found higher than semi-crystalline matrices.     

Study of active millimeter-wave image speckle reduction by Hadamard phase pattern illumination

Active millimeter-wave images typically exhibit characteristic speckle noise, due to the coherence of artificial millimeter-wave sources. We study the Hadamard speckle contrast reduction (SCR) technique, which has been successfully used in laser projection systems, in the context of millimeter-wave imaging. We show the impact of Hadamard pattern order and size and of image and pattern resolution on speckle reduction efficiency. Practical limitations of Hadamard pattern implementations and their effect on speckle reduction efficiency are also discussed.     

Flexural design curves of steel plate I-girders at elevated temperatures: I-girders with yield or local buckling failure mode

The present study was undertaken to characterize the structural behavior and ultimate flexural strength of steel plate I-girders under pure flexural moment at elevated temperatures. A novel design procedure along with flexural design curves was proposed to predict the flexural behavior of the I-girders and estimate corresponding ultimate flexural strengths. The main strategy of the procedure is to find an ambient-temperature equivalent of the I-girder by quantifying and formulating the effects of elevated temperatures. The proposed procedure comprises overall and partial phases. The former phase deals with the determination of equivalent laterally unbraced length, and the latter phase addresses the equivalent web and compression flange slenderness parameters. The calibration factor was defined to adapt the design curves to the effects of high compression flange slenderness parameters and residual stress at elevated temperatures. To generate comparative results, a numerical study was conducted by analyzing 216 finite element (FE) models. Fifty-four out of 216 FE models with different cross-sectional elements were dedicated to the I-girders fail by yield or local buckling failure mode, the results of which are reported in the present paper. Data fitting analysis was carried out to capture the variation of calibration factor with respect to compression flange slenderness parameters. By calibrating the proposed design procedure, the results were converged and, therefore, good conformity was reached between the numerical and parametric results.     

Effect of hydrogen combustion reaction on the dehydrogenation of ethane in a fixed-bed catalytic membrane reactor

A two-dimensional non-isothermal mathematical model has been developed for the ethane dehydrogenation reaction in a fixed-bed catalytic membrane reactor. Since ethane dehydrogenation is an equilibrium reaction, removal of produced hydrogen by the membrane shifts the thermodynamic equilibrium to ethylene production. For further displacement of the dehydrogenation reaction, oxidative dehydrogenation method has been used. Since ethane dehydrogenation is an endothermic reaction, the energy produced by the oxidative dehydrogena-tion method is consumed by the dehydrogenation reaction. The results show that the oxidative dehydrogenation method generated a substantial improvement in the reactor performance in terms of high conversions and significant energy saving. It was also established that the sweep gas velocity in the shell side of the reactor is one of the most important factors in the effectiveness of the reactor.     

Spare part requirement prediction under different maintenance strategies

Maintenance cost is a significant part of production costs. Hence, logistics and spare part management should be considered early in the design and operational phase. The reliability characteristic of the item can be used effectively to spare part prediction (SPP). In mining industries, the reliability characteristic can be affected significantly by the operational conditions. In this study, to have an accurate SPP, covariate-based reliability models have been used to estimate the required number of tire spare parts for a dump truck fleet. The outputs represent a significant difference in the required spare parts’ management, when considering and ignoring covariates.     

A new theorem on higher order derivatives of Lyapunov functions

The Lyapunov stability analysis method for nonlinear dynamic systems requires a non positive first derivative of the Lyapunov functions along the system’s trajectories. In this paper, a new method is developed to relax this requirement. A new sufficient condition is developed for the stability analysis of nonlinear systems, introducing some inequalities for higher order derivatives of the Lyapunov function. The differential inequalities can be considered as a new controllable canonical form linear time invariant system with negative inputs. The stability analysis of a given nonlinear system is then reduced to check if the characteristic equation for the new linear time invariant system is Hurwitz. Some examples are presented to establish the approach.