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. Manuscript profile

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. Manuscript profile

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. Manuscript profile

The purpose of this study is to find solutions to improve the acoustic characteristics of therapeutic spaces in the design and construction phases. In many architectural designs, the importance of acoustics is not considered, although the acoustic performance of buildings is of importance in many cases. Hospitals are one of such cases. This study is focused on the effect of the geometry and material of the internal walls of the patient's hospital room on its acoustic performance through computer acoustic simulations. Acoustic simulations have been implemented in Odeon software. The acoustic calculations in this software are geometric and the most important acoustic parameters of the patient's room have been investigated. Reverberation time is one of the key parameters. A set of dimensions and common materials for a hospital room were considered as input for acoustic simulation. The results of this research specifically suggest the optimal dimensions and materials of a three-bed patient room. Based on the simulations, a three-bed room with dimensions 5.3 x 1.7 square meters and vinyl wall material leads to the optimal amount reverberation time. Although the use of porous acoustic material in the walls can significantly improve the acoustic characteristics of the room, but due to the health considerations of infectious environments, the use of such materials is not allowed. In some cases, conflicts arise between the methods of improving these multiple parameters. In this study, the reverberation time has the highest priority over other parameters. 5/3 × 1/7 متر مربع و جنس دیواره¬ وینیل منجر به مقدار بهینه زمان واخنش می¬شود. البته استفاده از متریال های اکوستیک، که عموما متخلخل می باشند، می تواند شرایط را بیش از این ارتقا دهد اما استفاده از چنین ساختارهایی به دلیل ملاحظات عفونی در مراکز درمانی مجاز نمی باشد. در برخی موارد تعارض میان روش های بهبود این پارامترهای چندگانه ایجاد می گردد. در این مطالعه، پارامتر زمان واخنش بالاترین اولویت را نسبت به سایر پارامترها دارد. Manuscript profile