Sharif Digital Repository

The noise emission level associated with two types of speed reducers has been investigated numerically and experimentally for different dimensions and different speeds of vehicle (20, 40 and 60 km/h) and zero acceleration. Numerical analysis has been performed using an FEM method in the ANSYS environment. The experiments show that for a bump of height 0.04 m, the peak noise level is increased by between 1 and 14 dB (A) whereas, for bump of height 0.055 m, the peak noise level increases by between 1 and 19 dB (A). There is an excellent agreement between the numerical and experimental results. © 2006 Elsevier Ltd. All rights reserved  

Polyether ether ketone (PEEK) is an appropriate biomaterial for orthopedic implant applications due to its superior mechanical properties, chemical resistance, nontoxicity, and Magnetic resonance imaging (MRI) compatibility. Unfortunately, the inherent bio-inertness of PEEK restricted its application and required some modification to provide better bioactivity. Besides it, the generated electrical signals in the bone due to its piezoelectricity features have a vital role in regulating bone repair and regeneration. We aimed to modify the surface of PEEK with a dual-functionality nanocomposite that provides surface bioactivity and simulates the piezoelectricity of bone. So, we introduced a... 

This paper aims to evaluate the seismic risk of the masonry school buildings located in the Tehran metropolis over the next 50 years and to prioritize them for seismic retrofitting toward optimal seismic risk mitigation. Tehran ranks among the world's largest cities facing a significant seismic hazard, and masonry buildings are identified as among the structural types exhibiting the poorest seismic performance. In addition, school buildings, due to their population density, are considered important buildings by many seismic codes; Consequently, it is vital to conduct a comprehensive seismic risk analysis for these buildings and strategically allocate limited resources to their seismic... 

Undoubtedly, metal corrosion is one of the most challenging problems faced by industries. Introducing corrosion inhibitors is a reasonable approach to protecting the metal surface. Due to environmental concerns and the toxicity of industrial organic corrosion inhibitors, researchers are continually exploring acceptable replacements. The current study focused on the application of Falcaria Vulgaris (FV) leaves extract to mitigate mild steel (MS) corrosion in a 1 M HCl environment. The polarization findings demonstrated that the corrosion current density decreased from 264.0 µA/cm2 (for the sample submerged in the blank solution) to 20.4 µA/cm2 when the optimal concentration of 800 ppm of FV... 

Solar Chimney Power Plant (SCPP) is a renewable energy system that indirectly converts solar energy to electricity. However, the efficiency of SCPP is not sufficient for practical applications. Integrating SCPPs with Photovoltaic-Thermal systems (PVT) could enhance their performance to levels acceptable for industrial adoption. This study investigates the combined SCPP-PVT performance for the weather conditions of Austin (Texas), San Diego (California), and Phoenix (Arizona), all on a similar latitude. Various configurations of this combined system are numerically simulated, and their efficiencies are compared with a conventional SCPP, SCPP-Photovoltaic (PV), and stand-alone PV modules.... 

Introduction: The study of abnormal aggregation of proteins in different tissues of the body has recently earned great attention from researchers in various fields of science. Concerning neurological diseases, for instance, the accumulation of amyloid fibrils can contribute to Parkinson’s disease, a progressively severe neurodegenerative disorder. The most prominent features of this disease are the degeneration of neurons in the substantia nigra and accumulation of α-synuclein aggregates, especially in the brainstem, spinal cord, and cortical areas. Dopamine replacement therapies and other medications have reduced motor impairment and had positive consequences on patients’ quality of life.... 

Aseptic loosening due to mechanical failure of bone cement is considered to be a leading cause of revision of joint replacement systems. Detailed quantified information on the number, size and distribution pattern of pores can help to obtain a deeper understanding of the bone cement's fatigue behavior. The objective of this study was to provide statistical descriptions for the pore distribution characteristics of laboratory bone cement specimens with different amounts of antibiotic contents. For four groups of bone cement (Palacos) specimens, containing 0.3, 0.6, 1.2 and 2.4 wt/wt% of telavancin antibiotic, seven samples per group were micro computed tomography scanned (38.97 μm voxel size).... 

The aim of this paper is to develop the technical knowledge, especially the optimum geometries, for the design and manufacturing of a supersonic gas-gas ejector for a wasteheat driven vehicle cooling system. Although several studies have been performed to investigate the effects of geometrical configurations of gas-gas ejectors, a progressive design methodology of an ejector compressor for application to a vehicle cooling system has not yet been described. First, an analytical model for calculation of the ejector optimum geometry for a wide range of operating conditions is developed, using R134a as the working fluid with a rated cooling capacity of 2.5 kW. The maximum values of entrainment... 

A reliable, fast, and cost-effective method of monitoring morphine (MO) concentration in biological fluids is highly desired in clinical and modern medicine. Nanotechnology has opened up new possibilities for developing morphine biosensors, but the most advanced electrodes available offer a detection limit (LOD) of ≥10 nM. This work introduces a new, ultrasensitive electrochemical biosensor based on microporous metal-organic frameworks (∼1100 cm2 g−1 surface area) modified by Ag clusters (∼2 nm) and functionalized by Au nanoparticles (∼180 nm). Electrochemical studies show that functionalizing the microporous crystalline particles (620 ± 45 nm) with metal nanoclusters enhances charge... 

The one-dimensional cutting stock problem has many applications in industries and during the past few years has been one of the centers of attention among the researchers in the field of applied operations research. In this paper, a revised version of Ant Colony Optimization (ACO) technique is presented to solve this problem. This paper is a sequel to the previous ACO algorithm presented by the authors. In this algorithm, according to some probabilistic rules, artificial ants will select cutting patterns and generate a feasible solution. Computational results show the high efficiency and accuracy of the proposed algorithm for solving one- dimensional cutting stock problem