Sharif Digital Repository

This paper considers the output feedback adaptive controller design problem for a class of discrete-time nonlinear systems in output feedback form with unknown control directions and preceded by unknown hysteresis. The problem of lacking in a-priori knowledge on the control directions and unknown hysteresis are solved by using the discrete Nussbaum gain and Prandtl-Ishlinskii model, respectively. The system is transformed into the form of a nonlinear auto regressive moving average (NARMA) model to construct an output feedback control. To overcome the noncausal problem in the control design, future output prediction laws and parameter update laws with the dead-zone technique are constructed... 

In this investigation, a mathematical model for HDS of diesel fuel in a slurry bubble column reactor was developed. The model is based on the axial dispersion of the heterogeneous gas flow regime, which includes two various bubble classes: large (20±70mm) and small (1±10mm). By assuming only large or large plus small bubbles in the column, single- and two-bubble class mode equations are developed. The developed models to solving the mass and enthalpy balances from which the sulfur conversion was obtained that undertaken. The chemical kinetics over NiMoS/γ-Al2O3 catalyst were undertaken for the reaction rate of the involved reactions. The reactor operating conditions... 

The influence of equal channel angular pressing (ECAP) on microstructure and mechanical behavior, as well as, strain aging during ECAP and post-ECAP of Mg-1.8Zn-0.7Si-0.4Ca biomedical alloy was examined. The alloy in solid solution heat-treated condition was processed by ECAP with route BC at 350 and 400 °C. The specimens ECAPed at 350 °C were aged at 125 and 150 °C for different times. The hardness and shear punch test results indicated that performing ECAP at 350 °C for 4 passes increases the hardness and shear strength of the alloy from 48 HV and 110 MPa to 71 HV and 188 MPa, respectively. It was revealed that the average grain size of the alloy decreases from 78 µm to about 3 µm after 4... 

In a distributed system, each solution for the problem of Byzantine agreement requires that some of the correct processes reach a common decision value from a set of proposed values while Byzantine processes may behave arbitrarily. While the problem has been widely studied in fully connected fixed networks, few studies have been carried out in the context of self-organizing mobile networks such as mobile ad hoc networks. We present a randomized consensus protocol with three additional modules for the case of dynamic networks: participant detectors, failure detectors and maintainer. We assume an asynchronous network with unknown participants where processes can be fixed or move continuously... 

The global energy crisis and harmful effects of fossil fuel usage as well as the rapid rate of electricity price growth forces Data Centers (DCs) providers to install on-site Renewable Energy (RE). However, the huge installation investment, as well as fluctuating characteristic, impedes the widespread usage of RE. Reducing the break-even time of the required investment is a reinforcing economic incentive that complements the environmental incentive to further encourage DC Providers to use more RE. This paper takes advantages of an economic opportunity, namely the electricity pricing models, as well as a technological opportunity, namely the distributed Uninterruptable Power Supply (UPS)... 

In this paper, we consider the problem of multiuser detection in the presence of users with unknown signature codes for a synchronous coded CDMA system. Interference suppression for unknown users is done by projecting the received signal on the null space of known users and then using eigenvalue decomposition and subspace techniques to derive a detector that cancels the known interference and successfully mitigates the unknown interference. Significant performance gains over detectors that ignore unknown users and treats them as noise is achieved. © 2001 IEEE  

Optimal investment and operations of integrated local energy systems (ILESs) require medium to long-term prediction of energy consumption. To forecast load profiles, deep recurrent neural networks (DRNNs) are becoming increasingly useful due to their capability of learning uncertainty and high variability of load profiles. However, to explore and choose a DRNN model, out of conceivably numerous configurations, depends entirely on the performing task. In this regard, we tune and compare seven DRNN variants on the task of medium and long-term predictions for heating and electricity consumption. The ultimate DRNN model outperforms two state-of-the-art machine learning techniques, namely... 

In this study, a set of constitutive equation corrected for deformation heating is proposed for a near equiatomic NiTi shape memory alloy using isothermal hot compression tests in temperature range of 700 to 1000 °C and strain rate of 0.001 to 1 s -1. In order to determine the temperature rise due to deformation heating, Abaqus simulation was employed and varied thermal properties were considered in the simulation. The results of hot compression tests showed that at low pre-set temperatures and high strain rates the flow curves exhibit a softening, while after correction of deformation heating the softening is vanished. Using the corrected flow curves, the power-law constitutive equation of... 

In this study, a three-dimensional mathematical model, based on a nonuniform droplet concentration distribution, has been developed to simulate gas absorption in a venturi scrubber. The mass transfer process was illustrated by assuming the liquid phase as a combination of droplets and film. The flow, just as the annular two-phase flow, includes a flow of liquid film layer on the walls and a flow of gas and liquid drops in the core. Peclet number was determined using experimental data reported by Viswanathan et al. (1984) for distribution of droplets across the cross section of the scrubber. The mathematical model for gas absorption was justified by comparing the theoretical predictions with... 

In this paper, we present a novel and rather simple method for calculating reverse-link outage probability in signal-to-interference ratio (SIR)-based power-controlled direct-sequence code-division multiple access (DS-CDMA) systems. We obtain outage probability for a single-service system using the interference-to-received-signal-power ratio. We extend our method to the multiservice case using the uplink load factor, which is the ratio of the interference to the interference plus noise. Unlike most of the previous works, we employ the 2-D Poisson point process to model the spatial distribution of mobile users in the network coverage area. We approximate the... 

Polycrystalline (Pr1-xBax)Ba2Cu3O 7-δ samples with 0.0 < x < 0.6 are prepared by the standard solid state reaction technique. X-ray diffraction and resistivity measurements are performed. For x < 0.3, the 123 phase is formed, but for x > 0.3, due to the solubility limit, the 123 phase is not the dominant phase. The normalized resistivity increases with the increase of Ba doping to about x = 0.08, and then decreases in the 123 phase up to x = 0.3. The existence of an extremum in the resistivity is explained as the competition between scattering by impurities and increase of the number of carriers by Ba doping. For x > 0.3, due to a large increase in the non-123 phase formation, the... 

Polycrystalline (Pr1-x Bax)Ba2Cu 3O7-δ samples (0.0 ≤ x ≤ 0.6) is prepared by the standard solid state reaction technique. X-ray measurements confirm the formation of the 123 phase for x ≤ 0.3, but for 0.4 ≤ x ≤ 0.6, due to the solubility limit, the 123 phase is not a dominant phase. Resistivity measurements show the increasing of resistivity with the increase of Ba-doping up to about x=0.08, and then decreases in the 123 phase up to x = 0.3. There is no observation of superconducting state in our samples, but we observe the sharp decrease of resistivity for x>0.1, which is related to possible superconductivity in Pr123 system by Ba-doping. It is concluded that the Pr/Ba disorder has... 

Growth arrest-specific gene 6 (GAS6) is a growth factor-like cytokine whose function is related with vitamin K. This protein interacts with receptor tyrosine kinase proteins such as Tyro3, Axl, and TAM Receptor family, therefore affecting the tumorigenic processes via different mechanisms. GAS6-antisense 1 (GAS6-AS1) is a long non-coding RNAs (lncRNAs) that is transcribed from a genomic regions nearby GAS6. This lncRNA is also implicated in the pathobiology of cancer. We intended to judge the role of GAS6 and GAS6-AS1 in the pathogenesis of breast cancer through appraisal of their expression levels in breast cancer tissues and their paired neighboring non-cancerous samples. Expression of... 

Nowadays, geo-distributed Data Centers (DCs) are very common, because of providing more energy efficiency, higher system availability as well as flexibility. In a geo-distributed cloud, each local DC responds to the specific portion of the incoming load which distributed based on different Geographically Load Balancing (GLB) policies. As a large yet flexible power consumer, the local DC has a great impact on the local power grid. From this point of view, a local DC is a good candidate to participate in the emerging power market such as Regulation Service (RS) opportunity, that brings monetary benefits both for the DC as well as the grid. However, a fruitful collaboration requires the DC to... 

Nowadays, geo-distributed Data Centers (DCs) are very common, because of providing more energy efficiency, higher system availability as well as flexibility. In a geo-distributed cloud, each local DC responds to the specific portion of the incoming load which distributed based on different Geographically Load Balancing (GLB) policies. As a large yet flexible power consumer, the local DC has a great impact on the local power grid. From this point of view, a local DC is a good candidate to participate in the emerging power market such as Regulation Service (RS) opportunity, that brings monetary benefits both for the DC as well as the grid. However, a fruitful collaboration requires the DC to... 

The multiphysics process of the electromagnetic (EM) radiation induced from an embedded nanofiber scatterer subjected to SH-waves is of interest. By discarding the commonly employed electroquasistatic approximation, the fully-coupled elastodynamics and Maxwell's equations have been solved simultaneously within the mathematical framework of piezoelectric surface elasticity theory. Certain subtleties regarding the introduced interface characteristic lengths that make the examination of the size effect on the EM radiated power, scattering cross section, fundamental resonance frequency, and distribution of the magnetic field possible will be discussed. The obtained results can be helpful for... 

Nowadays, the fast rate of technological advances, such as cloud computing, has led to the rapid growth of the Data Center (DC) market as well as their power consumption. Therefore, DC power management has become increasingly important. While power forecasting can greatly help DC power management and reduce energy consumption and cost. Power forecasting predicts the potential energy failures or sudden fluctuations in power intake from utility grid. However, it is hard especially when variable renewable energies (RE) as well as free cooling such as air economizers are also used. Geo-distributed DCs face an even harder issue: since in addition to local conditions, the overall status of the... 

Urmia Lake River Basin (ULRB) is one of the most important habitats in the world and one of the major agricultural regions in Iran. On average, the ratio of irrigation to evapotranspiration in this basin is more than 73%. Investigating the irrigation water requirement pattern changes and the spatial distribution of evapotranspiration during the basin development period on a regional scale play important roles in understanding the basin situation. In this study, the actual evapotranspiration has been estimated by SEBAL model. By estimating the precipitation distribution in the basin, the agricultural irrigation water requirement pattern has been calculated using the land use map in 1995, 2010...