Sharif Digital Repository

Maintaining balance is an essential need for human. This ability is sometimes lost or weakened due to reasons such as muscle weakness, vision problems, and neuromuscular problems. It was difficult to accurately measure balance parameters in the past because it needs expensive equipment and the presence of a physiotherapist. In new clinical setups, accurate measurements of balance quality have become possible using advanced devices. These devices are also used to provide therapeutic exercises to improve the balance condition. One of the most famous products in this area is the Biodex balance SD. The cost of this device, however, is high and it is for research and clinical use. The purpose of... 

An experimental investigation was conducted to determine the effect of a uniform pitching motion on a axisymmetric body projectile undergoing excursions in angle of attack. Force and moment measurements were obtained for an axisymmetric body over a range of Reynolds numbers from 6.7×105 to 3.1×106 while varying the angle of attack from -3 to 12 degrees. The experiments included measuring the aerodynamic loads over a range of reduced frequencies, k = 0.0003 to 0.003. Steady state data were acquired and were used to provide a baseline for further analysis and comparison. The model was oscillated with amplitude of 2 and 4 degrees at two different mean angles of attack of 0 and 4. Shadowgraph... 

Parkinson's disease impairs the patients' balance with the degeneration of the neurons related to their postural control. There are many rehabilitation methods to preclude the disease or weaken its effects. To assess the influence of these methods and their outcome, there are two main evaluation methods, including clinical (qualitative and dependent on the presence of a therapist) and quantitative, such as posturography. Using control models is one of the quantitative methods researchers have been used for more than three decades. Considering this and what have been done in the literature, the purpose of this research is to develop a balance assessment method in dynamic tasks, such as the... 

A signed graph is a graph with a sign attached to each edge. This article extends some fundamental concepts of the Laplacian matrices from graphs to signed graphs.In particular, the largest Laplacian eigenvalue of a signed graph is investigated,which generalizes the corresponding results on the largest Laplacian eigenvalue of a graph.It is proved that (C2n+1; +) is uniquely determined by its Laplacian spectrum (or is DLS), where (C2n+1; +) is a signed cycle in which all edges have positive sign. On the other hand, we determine all Laplacian cospectral mates of (C2n; +) and hence (C2n; +) is not DLS. Also, we show that for every positive integer n, (Cn;) is DLS. Then, we study the spectrum of... 

In this project, a system designed for balancing a flexible rotor, without any need for shutting down the rotor. Then, functionality of this system, studied with experimental assessments. The method used in this plan, is classified into active online balancing methods of rotors which can change the mass distribution of the rotor, to improve the balancing condition, during operation. In order to reach this goal, a balancer plane is designed that by angular displacement of two nonconcentric masses, each driven with an electrical actuator, sets a desired unbalancy vector. Then, a rotor designed, which after mounting balancer plane, could be classified into the flexible rotors according to...