Sharif Digital Repository

This paper presents the results of parametric analyses of the yielding moment (My) of Bolted Flush Endplate Beam (BFEB) splice connections using Finite Element Modeling (FEM) tools. The connection components were modeled using three-dimensional brick elements, while contact between the endplates was modeled using Coulomb friction. Materials for beam, endplate and bolts were considered to behave non-linearly. Finite element results with three experimental and numerical studies were compared, and all indicated good agreement, which is also briefly reviewed in this paper. Using verified FEM, fairly large parametric studies, based on the practical configuration of BFEB connections, were carried... 

Existing design procedures for steel frames have been modified during the last three decades to incorporate the semi-rigid behavior of the connections into the frame design advancement. Knowledge in initial rotational stiffness of a connection is important for the global elastic analysis of frame structures. This paper presents the results of several parametric analyses on the Initial Rotational Stiffness (IRS or Sini) of Bolted Flush End-plate Beam (BFEB) splice connections using Finite Element Modeling (FEM). The FEMs have taken into account material behavior, geometrical discontinuities and large displacements. The analyses have been calibrated to experimental results that are also... 

Bolted Column Base Plate (BCBP) connections are widely used to connect steel columns to the concrete foundations. This paper conducts a parametric study on the initial stiffness of bolted base plate with Square Hollow Section (SHS) column connection, through an extended 3-D Finite Element Modeling (FEM). Different features of the connection such as material behavior, geometric details, typical contact phenomena and large displacements are also considered in the modeling. A comparison between experimental test and FEM is carried out to illustrate the ability of the numerical method to simulate the connection behavior. An analytical explanation on the initial stiffness of the connection is... 

In this paper, the semi-rigid connections, such as Double-angle Web (DW) connections, which are welded to the beam web and bolted to the column ange, are investigated. This study tries to establish the eect of clearance setback between beam end and column ange and/or web. When the beam rotates, it is desirable to avoid bottom ange of the beam bearing against the column as this can induce large forces on the connection. The usual way of achieving this is to ensure that the connection extends at least a few millimeters beyond the end of beam. For this purpose, several connections are designed and considered based on two dierent shear capacities for the beam. For each connection, two dierent... 

The compressive strength of mass concrete in dams is obtained from laboratory experiments of various cylindrical specimens with diameters of 150, 250, and 300 mm, and heights of 300, 500, and 450 mm, respectively. These specimens with 37.5, 75, and 150 mm maximum size of aggregate were investigated. The 7- and 90-day compressive strength of concrete was found to be between 20 and 58 MPa depending on the size of the specimens. The results reveal the existence of a significant size effect. Based on test results, relationships between the strength of mass concrete specimens and their size and shape are developed. Finally, results and a discussion are presented regarding compressive strength... 

A new exponential model to depict the moment-rotation (M-θ) relationship of Bolted Endplate Connections (BEC) is proposed. The proposed model represents an approach to the prediction of M-O curves, taking into account the possible failure modes and the deformation characteristics of the connection elements. The presented model has three physical parameters, along with two curve-fitted factors. These physical parameters are generated from dimensional details of the connection, as well as the material properties. By employing simplified connection behavioral models to estimate the connection M-θ behavior, analytical expressions for evaluating major connection parameters, such as initial... 

In this paper, we use simulated annealing heuristics for constructing an intrusion detection system (IDS). The proposed IDS combines the learning ability of simulated annealing heuristics with the approximate reasoning method of fuzzy systems. The use of simulated annealing is an effort to effectively explore the large search space related to intrusion detection problems, and find the optimum set of fuzzy if-then rules. The aim of this paper is to present the capability of simulated annealing based fuzzy system to deal with intrusion detection classification problem as a new real-world application area. Experiments were performed with KDD-Cup99 intrusion detection benchmark data set. © 2008... 

Due to the wide usage of rotary equipment and the necessity of their testing for maintenance and repair, test rigs have become necessary. The mechanical closed-loop test rig developed in Sharif University of Technology branch of ACECR (Academic Centre of Education, Culture and Research) is a test rig with low energy losses that is suitable for testing high power gearboxes such as aerospace or wind turbine gearboxes. It can be loaded up to 489Hp at a maximum speed of 3000 rpm, and the test components can be tested in different testing conditions including a variety of torques and speeds. This paper describes the preliminary, conceptual, and detailed design, steps including frame work design,... 

A new manganese complex of the formula [Mn(tptz)(OH 2) 3](CF 3SO 3) 2·EtOH, (1, where tptz = (2,4,6-tris(2-pyridyl)-1,3,5-triazine) is presented, exhibiting an excellent catalytic activity and selectivity in oxidation of various sulfides to the corresponding sulfoxides with UHP (urea hydrogen peroxide) as oxidant under air at room temperature. A modified preparation procedure produces another new manganese complex of the formula [Mn(tptz)(CH 3COO)(OH 2) 2](CF 3SO 3)·3H 2O (2). X-ray structures of both Mn(II) complexes, properties (elemental analysis, electrochemistry, EPR, IR, Raman, and UV-Vis spectra), as well as DFT studies results are reported  

In this paper, the use of simulated annealing (SA) metaheuristic for constructing a fuzzy classification system is presented. In several previous investigations, the capability of fuzzy systems to solve different kinds of problems has been demonstrated. Simulated annealing based fuzzy classification system (SAFCS), hybridizes the learning capability of SA metaheuristic with the approximate reasoning method of fuzzy systems. The objective of this paper is to illustrate the ability of SA to develop an accurate fuzzy classifier. The use of SA in classification is an attempt to effectively explore and exploit the large search space usually associated with classification problems, and find the... 

This article delves into the challenging supply chain management domain, explicitly addressing the intricate issue of perishable inventory allocation within a two-echelon supply chain. The approach outlined here leverages deep reinforcement learning with a keen understanding of the inherent stochasticity arising from uncertain demands and variable supply conditions. The examined supply chain encompasses two retailers and a central distribution center operating under a vendor-managed inventory system. The primary goal of this research is to combat the prevalent problems of wastage and shortages frequently encountered at the retail level in such supply chains. The study employs the Advantage... 

Routinely, behavior of floor diaphragms is assumed completely rigid in their plane, which leads to erroneous results in analysis and design of some particular buildings. In this study, 4-story RC buildings, with end shear walls and plan aspect ratio of 3, are considered in order to investigate the influence of diaphragm openings on their seismic response. It is concluded that although in-plane floor flexibility has enormous effects on pre-yielding part of pushover curve, it has no influence on post-yielding part of that. Furthermore, the opening beside shear walls has crucial impact on response of building. Hence, it would be better off avoiding opening near the shear walls; if not, the... 

Nonlinear flexural behavior of elastic nano-beams under static loads is investigated in the framework of the Eringen’s nonlocal integral elasticity. The integro-differential and boundary conditions of equilibrium for inflected Timoshenko–Ehrenfest elastic beams with von Kármán nonlinear strains are established by using the minimum total potential energy principle. Eringen’s nonlocal differential law, consequent (but not equivalent) to Eringen’s nonlocal integral convolution, is well established to be inconsistent when applied to bounded domains of nano-mechanics interest. Accordingly, nonlocal integral elasticity formulation is utilized to capture scale effects in the nonlinear flexure of... 

Using hybrid energy storage system is a method for increasing the storage capability of solar thermal energy. If multiple energy storage devices with complementary performance characteristics are used together, the resulting system will be a 'Hybrid Energy Storage System'. In other words, a Hybrid Energy Storage System (HESS) has several media available for storage at any time. In this way, increase in storable energy is obtained without increasing collectors' area. When there are more than one storage mediums, the system should be able to choose the best medium for storing energy according to the conditions. In the previous works, an optimizer program was used to find the proper medium... 

Using hybrid energy storage system is a method for increasing the storage capability of solar thermal energy. If multiple energy storage devices with complementary performance characteristics are used together, the resulting system will be a 'Hybrid Energy Storage System'. In other words, a Hybrid Energy Storage System (HESS) has several media available for storage at any time. In this way, increase in storable energy is obtained without increasing collectors' area. When there are more than one storage mediums, the system should be able to choose the best medium for storing energy according to the conditions. In the previous works, an optimizer program was used to find the proper medium... 

The application of higher order continuum theories, with size effect considerations, have recently been spread in the micro and nano-scale studies. One famous version of these theories is the couple stress theory. This paper utilizes this theory to study the anti-plane problem of an elliptic nano-fiber, embedded in an infinite medium, both made of centrosymmetric isotropic material. In this framework, a characteristic length appears in the formulation, by which examination of the size effect is possible. This work presents an analytical solution for the proposed problem. Copyright © 2008 by ASME  

Gradient reproducing kernel particle method (GRKPM) is a meshless technique which incorporates the first gradients of the function into the reproducing equation of RKPM. Therefore, in two-dimensional space GRKPM introduces three types of shape functions rather than one. The robustness of GRKPM's shape functions is established by reconstruction of a third-order polynomial. To enforce the essential boundary conditions (EBCs), GRKPM's shape functions are modified by transformation technique. By utilizing the modified shape functions, the weak form of the nonlinear evolutionary Buckley-Leverett (BL) equation is discretized in space, rendering a system of nonlinear ordinary differential equations... 

In this work, a method for increasing the storage capability of a solar thermal energy system has been discussed. The system includes two tanks with the flexibility in choosing the best storage medium on the basis of the solar collector's outlet temperature. The results show that using such a hybrid storage system, the storable energy can be increased. Comparing the results with those for simple common storage systems, the extent of improvement was calculated. For verification of the results, a small pilot system was assembled. The test apparatus operated during 2008-2009 cold months and the parameters were recorded. Comparison of the theoretical and experimental results showed a good... 

The process of scanning the events occurring in a computer system or network and analyzing them for warning of intrusions is known as intrusion detection system (IDS). This paper presents a new intrusion detection system based on tabu search based fuzzy system. Here, we use tabu search algorithm to effectively explore and exploit the large state space associated with intrusion detection as a complicated classification problem. Experiments were performed on KDD-Cup99 data set which has information about intrusive and normal behaviors on computer networks. Results show that the proposed method obtains notable accuracy and lower cost in comparison with several renowned algorithms