Formation-Containment Control Using Dynamic Event-Triggering Mechanism for Multi-Agent Systems

The paper proposes a novel approach for formation-containment control based on a dynamic event-triggering mechanism for multi-agent systems. The leader-leader and follower-follower communications are reduced by utilizing the distributed dynamic event-triggered framework. We consider two separate sets of design parameters: one set comprising control and dynamic event-triggering parameters for the leaders and a second set similar to the first one with different values for the followers. The proposed algorithm includes two novel stages of co-design optimization to simultaneously compute the two sets of parameters. The design optimizations are convex and use the weighted sum approach to enable a structured trade-off between the formation-containment convergence rate and associated communications. Simulations based on non-holonomic mobile robot multi-agent systems quantify the effectiveness of the proposed approach.      

Thermodynamic evaluation of integrated gasification combined cycle: Comparison between high‐ash and low‐ash coals

In the present study, a coal‐integrated gasification combined cycle power plant is simulated. A high‐ash coal and low‐ash coal are considered to compare the performance of the plant. The combined cycle is in typical commercial size with 450 MW capacity. The feeds are Tabas and Illinois #6 coals which approximately contain more than 30% and 10% ash and have higher heating values of 22.7 MJ/kg and 26.8 MJ/kg, respectively. Energy and exergy analyses are done by aspen plus ^® and ees , respectively. Energy analysis shows that the overall efficiencies of power plants using high‐ash and low‐ash coals are 33% and 28%, respectively. The result shows that in high‐ash case, 52 kg/s coal, 10 kg/s water, and 1050 kg/s air and in low‐ash case, 48 kg/s coal and 820 kg/s air are required for providing mentioned power, approximately. Exergy analysis shows that maximum exergy destruction is in heat recovery steam generator unit. Investigating the emissions shows that high percent of ash in the coal composition has slight effects on the IGCC pollution. Finally, from thermodynamic viewpoint, it is concluded that the high‐ash coal, like the conventional one, can be used as thermally efficient and environmentally compatible feed of IGCCs. Copyright © 2016 John Wiley & Sons, Ltd.     

Passive Behavior of Ultra-Fine-Grained 1050 Aluminum Alloy Produced by Accumulative Roll Bonding in a Borate Buffer Solution

In this study, the effect of the ARB process on the passive behavior of ultra-fine-grained 1050 aluminum alloy in a borate buffer solution(p H 6.0) has been investigated. The result of the microhardness tests revealed that the microhardness values increase with an increasing number of ARB cycles. The potentiodynamic polarization plots revealed that the higher number of cycles for the specimens proceeds with the ARB process rather than annealing yield to lower corrosion and passive current densities and more noble corrosion potential values. Moreover, electrochemical impedance spectroscopy measurements showed that increasing the number of ARB cycles offers better conditions for forming the passive films.     

Study of a novel and simple method of generating binary mask for microprism fabrication

A new and simple method for generating binary masks for fabrication of gray scale micro-optical elements is proposed and examined. In this technique the main idea is superimposing two or more gratings with slightly different pitches that depend on the considered gray tone level. This causes generation of a chirped binary mask in which the openings widths are changed from a maximum to minimum through considered steps. Furthermore, to show its capability, it was applied to fabricate some microprisms. In addition, influence of proximity gap, and designation parameters on the surface quality were studied. It is shown that surface deterioration is effectively modified by optimizing the designation parameters. In comparison to other techniques, one of the advantages of this method is to have an assortment of pulse modulated masks that are able to create a variety of gray tone levels. Other advantages are ease in designation and implementation, and the fact that surface roughness could be smoothed effectively by aptly optimized parameters. Theoretical approach, simulation works, and experimental results are presented.     

Periodically focused modes in chains of dielectric spheres

We show that, theoretically, Brewster angle conditions for transverse magnetic polarized rays can be periodically reproduced in chains of spheres with index n?=?[Formula: see text] giving rise to lossless periodically focused modes with 2D period, where D is the sphere diameter. Using ray tracing for a spherical emitter with the diameter D we show that chains of spheres work as filters of such modes at 1.72?相似文献   

Shake table response and analysis of a concrete-filled FRP tube bridge column

The seismic performance of a concrete filled fiber reinforced polymer (FRP) tube (CFFT) bridge column was studied through shake table testing and nonlinear dynamic analyses of a one-fifth scale two-column bridge pier that also incorporated a conventional RC column. The FRP tube in the CFFT column was a prefabricated composite pipe with glass fibers aligned in ±55° with respect to the tube axis to provide both hoop and longitudinal strengths. The columns had nearly the same flexural capacities. The accumulated dissipated hysteresis energy of the CFFT column normalized by steel ratio was 1.6 times larger than that of the RC column; yet, it remained visibly damage free up to a drift ratio of 7%. The CFFT column failed due to FRP tube rupture under 8.4% drift ratio. The equivalent plastic hinge length of CFFT column was found to be more than twice that of the RC column, which implies larger spread of plasticity and smaller local ductility demands. The nonlinear dynamic modeling of the pier response using OpenSees led to very good agreement with the measured response of the pier under moderate and large-amplitude motions.