Sharif Digital Repository

Throughout this paper four locomotion mechanisms have been presented for underwater robo-sankes. In this respect; initially, two methods of locomotion including traveling and standing wave have been examined. Next, applications of these methods are described. Ultimately, assessing and comparison of those mechanisms have been studied and the best plan is determined. © 2009 WASET.ORG  

Flexible all-solid-state supercapacitors are promising electronic devices have been developed in the past decade. Recent efforts to develop such systems are as to construction of free standing electrodes with high specific capacitance. Among these developments, construction of carbon-based current collectors, with high surface areas and good mechanical properties via a facile and economic way, has been taken a great deal of attention. In this study, porous graphene were used as current collector for placement of the carbon fibers functionalized with polyaniline, to prepare a free-standing supercapacitor electrode through a new and facile method. This method begins through blending of the... 

Electrical power system is subjefcted to disturbances. A large disturbance may bring the system to the complete blackout or partial outage. Restoration of power system to normal state constitutes several stages including transmission line connection. In closing network loops, power system operators sometimes encounter an excessive Standing Phase Angle (SPA) across a line. SPA should be within allowable limits before any attempt is made to close breaker. In this paper, the effect of reduction of SPA in improving transient stability and impact on adjacent generators is discussed. Also, the effect of closing of breakers at two ends of the line is studied. At the end, the effect of loading... 

In this paper we introduce a Simplified Single Particle Model (SSPM), which is obtained from the general mathematical formulation of Li-ion batteries. The model is validated by using different commercial graphite/LiFePO4 cells, and results show agreement with more complicated models and experimental data for low operating currents of less than 1C. A maximum relative error of less than 2% can be observed to estimate cell voltage in the plateau region of the charge/discharge curves. Therefore, the proposed model is suitable in the case of stand-alone renewable energy systems, where battery current is typically lower than C/10. By increasing the current, the SSPM deviates from more accurate... 

This study is concerned with numerical modeling of viscous surface wave motion using boundary element method (BEM). The equations of motion for thin boundary layers at the solid surfaces are coupled with the potential flow in the bulk of the fluid, and a mixed BEM-finite difference technique is used to obtain the surface wave motion characteristics including the decay rate. The technique is presented for a standing surface wave motion. The extension to other free surface problems is discussed  

During power system restoration, it is necessary to check the phase angle between two buses before closing circuit breakers to connect a line between them. A novel approach for reducing large standing phase angle (SPA) based on Genetic Algorithm (GA) is presented in this paper. The proposed approach starts with a state estimation on Wide Area Monitoring System (WAMS) data measurements and considering power system operation and angular stability constraints, seeks an optimal control action scenario for reducing SPA. Since these constraints are evaluated based on WAMS data, the presented approach is considerably high speed and accurate. As an optimization problem, objective function of the... 

Physical problems caused by fractures, aging, stroke, and accidents can reduce foot power; these, in the long term, can dwindle the muscles of the waist, thighs, and legs. These conditions provide the basis for the invalidism of the harmed people. In this study, a saddle-walker was designed and evaluated to help people suffering from spinal cord injury and patients with lower limb weakness. This S-AD works based on body weight support against the previously report designs. This saddle-walker consisted of a non-powered four-wheel walker helping to walk and a powered mechanism for the sit-to-stand (STS) transfer. A set of experiments were done on the STS in the use of the standard walker and... 

Human motion planning studies are of considerable importance in producing human-like trajectories for various industrial or clinical applications (e.g. assistive robots). In this case, the capability of Central Nervous System (CNS) in generating a large repertoire of actions can be inspirational to develop more efficient motion planning approaches. Here, inspired by structural and functional modularity in the CNS, a novel modular and hierarchical model is developed to plan the sit-to-stand (STS) transfer under varying environmental conditions. In this model, the planning process is distributed among several functionally simple modules. The cooperation of modules enables the model to plan the... 

In this paper an effective numerical technique is presented to model turbulent motion of a standing surface wave in a tank. The equations of motion for turbulent boundary layers at the solid surfaces are coupled with the potential flow in the bulk of the fluid, and a mixed BEM-finite difference technique is used to obtain the wave and boundary layer characteristics. A mixing-length theory is used for turbulence modeling. The results are compared with previous experimental data. Although the technique is presented for a standing surface wave, it can be easily applied to other free surface problems. Copyright © 2008 by ASME