In this paper, the problems arising from determining the modal properties of large and complex structures are investigated. For this purpose, the free interface component mode synthesis method has been used. In the following, Singular-Value Decomposition (SVD) is applied as a powerful mathematical tool to determine the appropriate coordinates to participate in the coupling process. Also, the effective error resources including modal shear error and the continuous systems overlapping error and their solution are introduced. Initially, a discrete system has been employed to investigate the free interface component mode synthesis method. Eventually, the studied main samples in this research are beam, plate and cylindrical shell. It is worth noting that the application of this method on the cylindrical shell has not been observed in previous researches. پرونده مقاله

Today, medical centers are considered to be healing environments. A healing environment provides a space with a positive effect on its occupants. Architecture has an undeniable role in creating such an environment. Comfort factors should be carefully considered when designing health centers. Amongst these factors, acoustic comfort in hospitals plays a prominent role. The adverse effects of noise on patients have been well documented in many studies. Architectural design can have a major impact on the quality of a hospital's acoustic comfort. In this article, studies related to the acoustic design of therapeutic buildings are reviewed. First, different approaches to building acoustic analysis will be reviewed. Then, architectural approaches for controlling noise pollution in medical centers are discussed. Common criteria concerning acoustic comfort in healthcare spaces are introduced. Major acoustic annoyance factors in medical centers are discussed and some potential solutions are presented. This review shows that factors such as site selection, arrangement of different sections, facilities, internal and external noise sources, geometry and structure of the interiors and construction materials have a direct impact on the acoustic comfort of the hospital. General guidelines in acoustical design of medical centers are presented. Some psychological and mental factors associated with acoustic annoyance have also been introduced. پرونده مقاله

In recent years, a wide range of potential applications of nano-tubes have been reported. Vibrational behavior of rotating nano-tubes can be a challenging aspect of such structures. Due to their low dimension, classical theories fail to predict accurate behavior of nano-structures. In the present paper, Eringen’s non-local theory has been employed to study the vibration characteristics of a rotating nanotube conveying fluid. The effects of the scale parameter, mass, fluid velocity and angular velocity on the vibration characteristics of a rotating nanotube conveying fluid were investigated. The stability of the structure in different conditions was also discussed. The results show that dimensionless mass parameter do not affect the critical fluid velocity in a non-rotating nanotube conveying fluid. At the same time, critical velocity decreases by increasing nonlocal parameter. Also in a rotating nanotube, this point is a function of mass parameter and decreases and then increases to somewhere near the moving start point as β increases. A reciprocal relation was noticed between critical fluid velocity and critical angular velocity. Moreover, assuming constant mass, the area of the stability zone becomes wider as the nonlocal parameter increases. پرونده مقاله