Iran University of Science and Technology

About: Iran University of Science and Technology is a education organization based out in Tehran, Iran. It is known for research contribution in the topics: Nonlinear system & Finite element method. The organization has 12917 authors who have published 24965 publications receiving 372013 citations. The organization is also known as: Governmental Technical Institute & Advanced Art College.

Review of the impact of urban block form on thermal performance, solar access and ventilation

Abstract: Cities use a big amount of energy resources and account for over 70% of global carbon emissions. Form and position of urban blocks not only influence the micro-climate but also the energy performance of each block; so, considering the building without studying the effect of its surroundings is senseless. This paper provides a review of research on the impact of urban block form on the environmental performance of buildings and their direct environment. For this purpose, all papers are categorised in three main groups: • Thermal behaviour inside and outside the building. • Solar access inside and outside the building. • Indoor and outdoor natural ventilation. A discussion of these studies reflects the impact of urban block form parameters on the energy performance of the building and reviews existing methods and techniques to predict thermal behaviour, solar access and ventilation on a neighbourhood scale. This study is useful for planners and architects who are responsible for decision-making during the design phase.

Application of shuffled frog-leaping algorithm on clustering

Abstract: Evolutionary algorithms, such as shuffled frog leaping, are stochastic search methods that mimic natural biological evolution and/or the social behavior of species. Such algorithms have been developed to arrive at near-optimum solutions to complex and large-scale optimization problems which cannot be solved by gradient-based mathematical programming techniques. The shuffled frog-leaping algorithm draws its formulation from two other search techniques: the local search of the “particle swarm optimization” technique and the competitiveness mixing of information of the “shuffled complex evolution” technique. Cluster analysis is one of the attractive data mining techniques which is used in many fields. One popular class of data clustering algorithms is the center-based clustering algorithm. K-means is used as a popular clustering method due to its simplicity and high speed in clustering large datasets. However, k-means has two shortcomings: Dependency on the initial state and convergence to local optima and global solutions of large problems cannot be found with reasonable amount of computation effort. In order to overcome local optima problem, lots of studies are done in clustering. In this paper, we proposed an application of shuffled frog-leaping algorithm in clustering (SFLK-means). We compared SFLK-means with other heuristics algorithm in clustering, such as GAK, SA, TS, and ACO, by implementing them on several simulations and real datasets. Our finding shows that the proposed algorithm works better than others.

A CSRR-Based Sensor for Full Characterization of Magneto-Dielectric Materials

Abstract: In this paper, a novel complementary split-ring resonator (CSRR)-based sensor for full characterization of magneto-dielectric materials is proposed. In general, the operation of microwave resonance-based sensor hinges on the shift in the resonance frequency and the change in the quality factor of the loaded structure. However, both the electric permittivity and the magnetic permeability of the material under test (MUT) have similar effect on the response of the sensor that makes the simultaneous determination of the permittivity and permeability challenging. To remove this difficulty, the main idea behind this paper is to localize the highest intensity of the electric and magnetic fields in two separate zones. By the analysis of the measured resonance frequency and quality factor, the real and imaginary parts of the electric permittivity and the magnetic permeability of the MUT can be determined. Although the characterization of the permittivity and permeability of materials using split-ring resonator and CSRR-based sensors has been widely used, to the best of our knowledge, the full characterization of magneto-dielectric materials using a single sensor has not yet been reported in this paper. As a proof of concept, the sensor was fabricated and used to measure the permittivity and permeability of several materials. Strong agreement between the extracted values and the reference data was achieved.

Surface effects on nonlinear free vibration of nanobeams

Abstract: The nonlinear flexural vibrations of micro- and nanobeams in presence of surface effects are studied within the framework of Euler–Bernoulli beam theory including the von Karman geometric nonlinearity. Exact solution is obtained for the natural frequencies of a simply-supported nanobeam in terms of the Jacobi elliptic functions by using the free vibration modes of the corresponding linear problem. Numerical results include the normalized natural frequencies of vibration as functions of mode number, vibration amplitude, and nanobeam length and thickness. Also, the influence of surface effects on the system phase trajectory is considered.