Sharif Digital Repository

This review aims to propose the integrative implementation of microfluidic devices, biomaterials, and computational methods that can lead to a significant progress in tissue engineering and regenerative medicine researches. Simultaneous implementation of multiple techniques can be very helpful in addressing biological processes. Providing controllable biochemical and biomechanical cues within artificial extracellular matrix similar to in vivo conditions is crucial in tissue engineering and regenerative medicine researches. Microfluidic devices provide precise spatial and temporal control over cell microenvironment. Moreover, generation of accurate and controllable spatial and temporal... 

The main focus of this study is to address the possibility of using molecular dynamics (MD) simulation, as a computational framework, coupled with experimental assays, to optimize composite structures of a particular electrospun scaffold. To this aim, first, MD simulations were performed to obtain an initial theoretical insight into the capability of heterogeneous surfaces for protein adsorption. The surfaces were composed of six different blends of PVA (polyvinyl alcohol) and PCL (polycaprolactone) with completely unlike hydrophobicity. Next, MTT assay was performed on the electrospun scaffolds made from the same percentages of polymers as in MD models to gain an understanding of the... 

In the image segmentation field, traditional techniques do not completely meet the segmentation challenges mostly posed by inherently fuzzy images. Fuzzy connectedness and fuzzy clustering are considered as two well-known techniques for introducing fuzzy concepts to the problem of image segmentation. Fuzzy connectedness-based Segmentation methods consider spatial relation of image pixels by "hanging togetherness" a notion based on intensity homogeneity. But, they do not inherently utilize feature information of image pixels. On the other hand, as the segmentation domain of fuzzy clustering-based methods is the feature space they do not consider spatial relations among image pixels. Recently,... 

Body posture measurement approaches, required in biomechanical models to assess risk of musculoskeletal injuries, are usually costly and/or impractical for use in real workplaces. Therefore, we recently developed three artificial neural networks (ANNs), based on measured posture data on several individuals, to predict whole body 3D posture (coordinates of 15 markers located on body's main joints), segmental orientations (Euler angles of 14 body segments), and lumbosacral (L5-S1) moments during static manual material handling (MMH) activities (ANNPosture, ANNAngle, and ANNMoment, respectively). These ANNs require worker's body height, body weight (only for ANNMoment), hand-load 3D position,... 

Steel shear panels in combination with bracing are a novel form of steel shear walls that eliminate large distributed loads to impose on primary beams along with columns. This paper presents the results of a comparative experimental program on two types of steel shear panels with and without stiffeners. For this purpose, the proposed quasi-static cyclic loading history of Federal Emergency Management Agency(FEMA) 461 was applied on two full-scale specimens. Structural steel was selected as the material of the panels, which were welded to the surrounding boundary elements. In addition, using finite element models, performed tests were simulated and scaling effects were investigated. This... 

Through the combination of two types of seismic resisting systems including braced frames and steel shear walls, braced steel shear panel systems can be formed. This new lateral load-resisting system solves some of the defects of current special steel shear walls, such as imposing significant loads on boundary elements along with gravity load effects. Analysis and design of this new structural system underline the importance of having simple and precise finite-element models. To this aim, this paper presents two types of equivalent braced frames termed ‘overall equivalent brace’ and ‘equivalent mid-brace’. The equations of brace area, material strength and strain-hardening ratio are obtained... 

Summary Conventional design methods do not ensure that the desired collapse mechanism is developed at target displacement. In this paper, a case study is presented to analyze concentrically braced frames with steel shear panel (CBFSP). Also, extensive investigation in the failure modes are made, to have the global yielding mode at the final state. For this purpose, each of one-story, three-story, six-story and nine-story CBFSP models were decomposed into three parts where the members' closed-form equations of internal forces were identified and superimposed. On the basis of the kinematic theorem of plastic collapse, the possible mechanisms and the related energy equations were defined to... 

This paper introduces a new earthquake-resistant building design featuring eccentrically braced frames with steel wall shear panels. It also proposes closed-form expressions for analysis and extension of the existing failure mode control design method for the new structural system. Closed-form equations for internal forces were obtained, and probable failure mechanisms and corresponding lateral load multipliers for secondary effects were identified. Selection of member profiles was completed by the mechanism equilibrium curve concept. Pushover modelling was then performed with plastic hinge distribution corresponding to failure mechanisms. Only small differences were found between the...