A parametric study on buckling loads and tension field stress patterns of steel plate shear walls concerning buckling modes

M. Azhari,P. Memarzadeh,M.M. Saadatpour 국제구조공학회 2006 Steel and Composite Structures, An International J Vol.6 No.1

A Steel Plate Shear Wall (SPSW) is a lateral load resisting system consisting of an infill plate located within a frame. When buckling occurs in the infill plate of a SPSW, a diagonal tension field is formed through the plate. The study of the tension field behavior regarding the distribution and orientation patterns of principal stresses can be useful, for instance to modify the basic strip model to predict the behavior of SPSW more accurately. This paper investigates the influence of torsional and out-of-plane flexural rigidities of boundary members (i.e. beams and columns) on the buckling coefficient as well as on the distribution and orientation patterns of principal stresses associated with the buckling modes. The linear buckling equations in the sense of von-Karman have been solved in conjunction with various boundary conditions, by using the Ritz method. Also, in this research the effects of symmetric and anti-symmetric buckling modes and complete anchoring of the tension field due to lacking of in-plane bending of the beams as well as the aspect ratio of plate on the behavior of tension field and buckling coefficient have been studied.

Effect of Chemical Composition and Dietary Enzyme Supplementation on Metabolisable Energy of Wheat Screenings

Mazhari, M.,Golian, A.,Kermanshahi, H. Asian Australasian Association of Animal Productio 2011 Animal Bioscience Vol.24 No.3

Three trials were conducted to determine the available energy of different wheat screening varieties collected from different locations of Khorasan in Iran. In experiment 1, chemical composition and the nitrogen corrected true metabolisable energy (TMEn) were evaluated. A precision-fed rooster assay was used, in which, each wheat screening sample was tube fed to adult roosters, and the excreta were collected for 48-h. In Exp. 2 and 3, five and two wheat screening verities-based diets with or without xylanase and phytase were fed to 16-day old battery reared chicks respectively, and total feed consumption and excreta were measured during next three days. The variable nature of wheat screening varieties led to significant differences in mean TMEn values (p<0.01). The TMEn values of samples determined with adult roosters varied by ${\pm}5.03%$ of the mean value ($3,097.65{\pm}49.32\;kcal/kg$) and ranged from 2,734.90 to 3,245.12 kcal/kg. There was a significant correlation (p<0.05) between crude fiber (CF), neutral detergent fiber (NDF), and acid detergent fiber (ADF) with TMEn, and the greatest correlation coefficient was observed between NDF and TMEn (r = -0.947; p<0.001). The optimal equation in terms of $R^2$ from using a single chemical analysis was obtained with NDF: TMEn = 4,152.09-27.80 NDF ($R^2$ = 0.90, p<0.0001), and the TME prediction equation was improved by the addition of the crude protein (CP) and ASH content to sequential analysis: TMEn = 3,656.97-28.65 NDF+32.54 CP+38.70 ASH ($R^2$ = 0.98, p<0.0001). The average AMEn values of 5 and 2 wheat screening varieties determined with young broiler chickens were $2,968.41{\pm}25.70\;kcal/kg$ and $2,976.38{\pm}8.34\;kcal/kg$ in Exp. 2 and Exp. 3, respectively. Addition of xylanase and phytase to wheat screenings resulted in significant (p<0.01) improvement in AMEn by 4.21 and 2.92%, respectively.

Detecting and mapping different types of iron mineralization in Sangan mining region, NE Iran, using satellite image and airborne geophysical data

Nazi Mazhari,Azadeh Malekzadeh Shafaroudi,Majid Ghaderi 한국지질과학협의회 2017 Geosciences Journal Vol.21 No.1

The Sangan mining region is the largest Fe skarn in western Asia has emplaced into the Khaf-Kashmar-Bardaskan volcano- plutonic belt in the NE Iran. In this region, carbonate rocks of Jurassic skarnified and hosted different epigenetic types of iron minerals, including magnetite, hematite, goethite, and limonite. The combination of remote sensing and airborne geophysical data is a powerful tool for mapping and interpreting iron mineralization in some area with intensely rugged topography or a broad expanse area, where systematic sampling and conventional geological mapping has some limitation and time consuming. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite data and airborne geophysical magnetometry data were used for evaluating and mapping different types of iron mineralization in the Sangan mining region. Preprocessing of the datasets involved band ratio (BR), principal component analysis (PCA), spectral angle mapper (SAM), and constrained energy minimization (CEM) of the visible-near infrared and short wave infrared ASTER data were used to map four types of iron minerals (magnetite, hematite, goethite, and limonite). For preparing a lithological mapp of this region, an RGB image produced by combination of BR and PCA, (R:(5+7)/6, G:PC3, B:PC 5). Implementing SAM and CEM technique were useful for mapping and detecting magnetite, hematite, goethite, and limonite. The Reduce To the Pole (RTP) map of the airborne geophysical magnetometry data is a practical tool for iron ore exploration that were used in this region for enhancing high anomalous signature of magnetite after extracting granitoid rocks. The integration of the extracted information from the ASTER image processing algorithms and geophysical magnetometry, mapped iron mineralization and identified new potential of high magnetite mineralization. The results verified by geological map and comprehensive fieldwork. This integration model can generalize to other arid and semi-arid regions with iron potential for both regional and district scales.

Design and Implementation of Sliding Mode-State Feedback Control for Stabilization of Rotary Inverted Pendulum

Samira Mir Mazhari Anvar,Iraj Hassanzadeh,Ghasem Alizadeh 제어로봇시스템학회 2010 제어로봇시스템학회 국제학술대회 논문집 Vol.2010 No.10

In this paper, design and implementation of stabilizing controller for Rotary Inverted Pendulum (RIP) which is an underactuated nonlinear mechanical system, is presented. A sliding mode-state feedback control scheme is proposed for the stabilization of the RIP system. In this scheme, genetic algorithm based state feedback control and sliding mode control (SMC) combined. After swinging up the pendulum, the proposed sliding mode control is activated and stabilized the pendulum (indirectly controlled mode) in upright position. In spite of being Insensitive to the model error and having the ability to globally stabilize the RIP system, undesirable chattering phenomenon and high amount of control energy consumption are the main disadvantages of implementing SMC. In order to eliminate the chattering phenomenon and reduce control energy after stabilization of the pendulum, the SMC switched to GA based state feedback control which is a smooth control law that stabilizes the system around equilibrium states. Experimental results of implementing proposed controller show a high performance of it in comparison to SMC.

A Survey on Asynchronous Quorum-Based Power Saving Protocols in Multi-Hop Networks

Imani, Mehdi,Joudaki, Majid,Arabnia, Hamid R.,Mazhari, Niloofar Korea Information Processing Society 2017 Journal of information processing systems Vol.13 No.6

Quorum-based algorithms are widely used for solving several problems in mobile ad hoc networks (MANET) and wireless sensor networks (WSN). Several quorum-based protocols are proposed for multi-hop ad hoc networks that each one has its pros and cons. Quorum-based protocol (QEC or QPS) is the first study in the asynchronous sleep scheduling protocols. At the time, most of the proposed protocols were non-adaptive ones. But nowadays, adaptive quorum-based protocols have gained increasing attention, because we need protocols which can change their quorum size adaptively with network conditions. In this paper, we first introduce the most popular quorum systems and explain quorum system properties and its performance criteria. Then, we present a comparative and comprehensive survey of the non-adaptive and adaptive quorum-based protocols which are subsequently discussed in depth. We also present the comparison of different quorum systems in terms of the expected quorum overlap size (EQOS) and active ratio. Finally, we summarize the pros and cons of current adaptive and non-adaptive quorum-based protocols.

Charge transport in polythiophene:fullerene:nanotube bulk heterojunction photovoltaic devices investigated by impedance spectroscopy

Arun Tej Mallajosyula,S. Sundar Kumar Iyer,Baquer Mazhari 한국물리학회 2013 Current Applied Physics Vol.13 No.4

P3HT:PCBM bulk heterojunction devices incorporating SWNTs, which are predominantly metallic in character, have been analyzed using impedance spectroscopy to understand the effect of SWNTs on their charge carrier transport properties. SWNTs reduce the effective lifetime of injected charge carriers. Frequency dependence of capacitance and conductance of P3HT:PCBM devices show monotonic variations without any clear peak positions. Simulations of the complex admittance of the P3HT:PCBM devices under trap free space charge limited current within the framework of SchereMontrol theory are used to qualitatively show that such characteristics are a signature of charge transport which is highly dispersive in nature. The position of peak speak in the imaginary part of impedance Im(Z), which is essentially same as the first transition frequency of ColeeCole plot, has a direct relation with the effective dc mobility of charge carriers which varies with dispersion parameters. Using the dc mobility values and the voltage variation of peak frequency of Im(Z), the ratio of sdc to speak has been calculated. The magnitude of this ratio is indicative of the degree of dispersiveness in transport. It has been shown that, SWNTs at low concentrations tend to reduce the dispersiveness in charge transport.

A Survey on Asynchronous Quorum-Based Power Saving Protocols in Multi-Hop Networks

Mehdi Imani,Majid Joudaki,Hamid R. Arabnia,Niloofar Mazhari 한국정보처리학회 2017 Journal of information processing systems Vol.13 No.6

Quorum-based algorithms are widely used for solving several problems in mobile ad hoc networks (MANET)and wireless sensor networks (WSN). Several quorum-based protocols are proposed for multi-hop ad hocnetworks that each one has its pros and cons. Quorum-based protocol (QEC or QPS) is the first study in theasynchronous sleep scheduling protocols. At the time, most of the proposed protocols were non-adaptiveones. But nowadays, adaptive quorum-based protocols have gained increasing attention, because we needprotocols which can change their quorum size adaptively with network conditions. In this paper, we firstintroduce the most popular quorum systems and explain quorum system properties and its performancecriteria. Then, we present a comparative and comprehensive survey of the non-adaptive and adaptivequorum-based protocols which are subsequently discussed in depth. We also present the comparison ofdifferent quorum systems in terms of the expected quorum overlap size (EQOS) and active ratio. Finally, wesummarize the pros and cons of current adaptive and non-adaptive quorum-based protocols.

Improvement of oxidation resistance of graphite by aluminosilicate coating with aluminum metaphosphate interlayer

M. Fekri,K. Jafarzadeh,S. A. Khalife Soltani,Z. Valefi,H. Mazhari Abbasi 한국탄소학회 2023 Carbon Letters Vol.33 No.7

In this research, in order to increase the oxidation resistance of graphite, kaolin and alumina powder with different ratios (26A-74S, 49A-51S, 72A-28S) and slurry method were used to create an aluminosilicate coating on the graphite substrate. In order to reduce the difference in the coefficients of thermal expansion of graphite with aluminosilicate coating, aluminum metaphosphate coating as an interlayer was prepared on the surface of graphite by cathodic electrochemical treatment. The isothermal oxidation test of the samples was carried out in air at a temperature of 1250 °C for 1, 3 and 5 h. The microstructure, chemical composition, and phase components of the coating were, respectively, analyzed by scanning electron microscope equipped with an energy-dispersive spectrometer and X-ray diffraction. The results indicated that, by increasing the withdrawal speed of the samples in slurry method, the amount of changes in the weight of the samples has increased and therefore had a direct effect on oxidation. In addition, it was approved that, at high-temperature oxidation, AlPO4 glass phase forms on aluminum metaphosphate interlayer which retards graphite oxidation. Along with aluminum metaphosphate, aluminosilicate coating also produces a glass phase which fills and seals the voids on the surface which prevents the oxygen to reach the surface of graphite. The created double-layer coating including an interlayer of aluminum metaphosphate + slurry coating prepared with the ratio of 26A-74S as the optimal coating in this research was able to increase the oxidation resistance of graphite by 73% at a temperature of 1250 °C.