Sharif Digital Repository

Supply chain management integrates planning and controlling of materials, information, and finances in a process which begins from suppliers and ends with customers. Optimal planning decisions made in such a distribution network usually include transportation, facilities location, and inventory. This study presents a new approach for considering customers’ differentiation in an integrated location-allocation and inventory control model using transfer recurrent neural network (RNN). In this study, a location and allocation problem is integrated with inventory control decisions considering two classes of strategic and non-strategic customers. For the first time, a novel transfer RNN is applied... 

In this paper, we present a computational study on the electrical behaviour of self-switching transistors (SSTs) based on InGaAs/InP heterojunction. Our simulation is based on the solution of Poisson and Schrodinger equations self-consistently by using Finite Element Method (FEM). By using this method, electrical characteristics of device, such as (Formula presented.) ratio, subthreshold swing, and intrinsic gate-delay time are investigated. Also, the effects of geometrical variations on the electrical parameters of SSTs are simulated. We show that appropriate design of the device allows current modulation exceeding (Formula presented.) at room temperature. © 2021 Informa UK Limited, trading... 

In recent years, convolutional neural networks and deep neural networks have been used extensively in various fields of analytical chemistry. The use of these models for calibration tasks has been highly effective; however, few reports have been published on their properties and characteristics of analytical figures of merit. Currently, most performance measures for these types of networks only incorporate some function of prediction error. While useful, these measures are incomplete and cannot be used as an objective comparison among different models. In this report, a new method for calculating the sensitivity of any type of neural network is proposed and studied on both simulated and real... 

In recent decades, population growth, agricultural development and climate change have caused environmental problems in the world, especially in the arid and semi-arid regions such as Iran. Urmia Lake, one of the unique biosphere reserves of the world, has suffered from these problems in the last 20 years. Although many studies conducted to the negative impacts of human-induced activities, especially agricultural expansion on the lake, few studies focused on providing restoration plans for that. This study uses a system dynamics method for modelling the restorations scenarios of Urmia Lake based on the prey-predator approach. This method is helpful to simplify the complicated feedbacks and... 

Making proper decisions in today's complex world is a challenging task for decision makers. A promising approach that can support decision makers to have a better understanding of complex systems is agent-based modeling (ABM). ABM has been developing during the last few decades as a methodology with many different applications and has enabled a better description of the dynamics of complex systems. However, the prescriptive facet of these applications is rarely portrayed. Adding a prescriptive decision-making (DM) aspect to ABM can support the decision makers in making better or, in some cases, optimized decisions for the complex problems as well as explaining the investigated phenomena. In... 

Socio-ecological systems include diverse resources of complexity involving complicated interactions, feedback, dynamic behavior patterns, heterogeneity in agents’ characteristics and behaviors, as well as system uncertainties. Agent-based modeling is introduced as a tool to simulate different levels of stakeholders and interactions, including individual, group, and institutional agents in complex socio-ecological systems. In the present study, an agent-based model was developed to explore sustainable solutions in uncertain conditions for groundwater restoration of a critical aquifer in the Lake Urmia Basin, Iran. Different projects for aquifer restoration such as wells monitoring, license... 

In this paper, we present a computational study on the electrical behaviour of self-switching transistors (SSTs) based on InGaAs/InP heterojunction. Our simulation is based on the solution of Poisson and Schrodinger equations self-consistently by using Finite Element Method (FEM). By using this method, electrical characteristics of device, such as (Formula presented.) ratio, subthreshold swing, and intrinsic gate-delay time are investigated. Also, the effects of geometrical variations on the electrical parameters of SSTs are simulated. We show that appropriate design of the device allows current modulation exceeding (Formula presented.) at room temperature. © 2021 Informa UK Limited, trading... 

Matrix sensing refers to recovering a low-rank matrix from a few linear combinations of its entries. This problem naturally arises in many applications including recommendation systems, collaborative filtering, seismic data interpolation and wireless sensor networks. Recently, in these applications, it has been noted that exploiting additional subspace information might yield significant improvements in practical scenarios. This information is reflected by two subspaces forming angles with column and row spaces of the ground-truth matrix. Despite the importance of exploiting this information, there is limited theoretical guarantee for this feature. In this work, we aim to address this issue... 

As a primary load-resisting component, annulus fibrosus (AF) maintains structural integrity of the entire intervertebral disc. Experiments have demonstrated that permanent deformation and damage take place in the tissue under mechanical loads. Development of an accurate model to capture the complex behaviour of AF tissue is hence crucial in disc model studies. We, therefore, aimed to develop a non-homogenous model to capture elastic, inelastic and failure responses of the AF tissue and the entire disc model under axial load. Our model estimations satisfactorily agreed with results of existing uniaxial (along fiber, circumferential and axial directions) and biaxial tissue-level tests. The... 

This study proposes a new approach to incorporate motion duration in incremental dynamic assessments. In the proposed methodology, at each intensity level, a simulation-based approach which is verified with actual data is employed to determine the median duration and the median acceleration spectra of ground motions expected to occur at the site. Afterward, at each intensity level, artificial or spectrally matched motions are produced based on the median acceleration spectra and the median duration, indicating that different intensity levels are directly covered by the generated artificial or adjusted motions rather than just scaling up and down a set of recorded ground motions. In the... 

absectionBackground Three types of sources can be considered in the analysis of multi-subject datasets: (i) joint sources which are common among all subjects, (ii) partially-joint sources which are common only among a subset of subjects, and (iii) individual sources which belong to each subject and represent the specific conditions of that subject. Extracting spatial and temporal joint, partially-joint, and individual sources of multi-subject datasets is of significant importance to analyze common and cross information of multiple subjects. New method: We present a new framework to extract these three types of spatial and temporal sources in multi-subject functional magnetic resonance... 

In this study, a novel artificial intelligence-based approach is presented to directly estimate the surface topography. To this aim, performance of different artificial intelligence-based techniques, including the multi-layer perceptron neural, radial basis function neural, and adaptive neural fuzzy inference system networks, in estimation of the sample topography is investigated. The results demonstrate that among the designed observers, the multi-layer perceptron method can estimate surface characteristics with higher accuracy than the other methods. In the classical imaging techniques, the scanning speed of atomic force microscope is restricted due to the time required by the oscillating... 

In the present study, the effects of Sr and Mg were investigated on mechanical and biological properties of 58S bioactive glass (BG). SiO2-P2O5-CaO BG with different contents of Sr and Mg were synthesized via the sol-gel method and immersed in simulated body fluid (SBF) for several days to explore their biocompatibility. Precise analyses of the BG using X-ray powder diffraction, scanning electron microscopy, and transmission electron microscopy showed that the Mg-doped BG containing 8 wt % MgO possessed better biocompatibility. It was also found that mechanical properties of the BG could be improved by increasing the amounts of MgO and SrO. Both 5Sr-BG and 8Mg-BG samples did not exhibit any... 

The high charge carrier recombination rate and weak oxygen evolution kinetics have impeded the efficiency of WO3 photoelectrodes for water splitting. We present a novel type II heterojunction semiconductor based on mixed WS2 and MoS2 nanosheets on WO3 nanoflakes hydrothermally grown on highly porous W skeletons. The chemically exfoliated transition metal dichalcogenide (TMD) sheets with submicrometric lateral sizes were deposited on the surface of WO3 nanoflakes by the electrophoretic technique to fabricate a staggered gap heterojunction. The photoanode exhibited an impressive current density of 14.9 mA cm−2 at 1.23 VRHE which comprised ∼1.7 mA cm−2 photocurrent under 100 mW cm−2 simulated... 

This article provides an agent-based model of a hypothetical standalone electricity network to identify how the feed-in tariffs and the installed capacity of wind power, calculated in percentage of total system demand, affect the electricity consumption from renewables. It includes the mechanism of electricity pricing on the Day Ahead Market (DAM) and the Imbalance Market (IM). The extra production volumes of Electricity from Renewable Energy Sources (RES-E) and the flexibility of electrical consumption of industries is provided as reserves on the IM. Five thousand simulations were run by using the agent-based model to gather data that were then fit in linear regression models. This helped... 

Power Distribution Unit (PDU) is a power supply unit that supplies various DC voltage levels for electric equipment. Reliability of PDU is very important in electrical systems. Buck converter is frequently used in PDU to provide the lower voltage levels than the source voltage level. The output capacitor of the buck converter is the main factor of failure. In this paper, we present a method to design a buck converter with almost no inductor current ripple. If the inductor current ripple is eliminated, the output capacitor can be removed from the converter. By removing the capacitor, the reliability and transient response of the converter can be improved considerably. The proposed method is... 

In this paper, we propose a novel wireless random access scheme, combining the CSMA/CA mechanism with two control signals for initiating new transmissions and announcing receiver busy status, respectively. We also develop a time-space framework of performance analysis, enabling separate study of the temporal and spatial efficiency of the random access, i.e. the scheme's ability for contention resolution and efficient performance in time, and its ability to provide for concurrent transmissions in space. Based on this framework and using both analysis and simulation, we show that the proposed scheme outperforms the IEEE 802.11 DCF, in terms of the overall afforded throughput, and also in terms... 

This paper presents a numerical analysis for Cu-water nanofluid flow through a circular duct inserted with cross-cut twisted tape with alternate axis (CCTA). Three dimensional (RNG) k − ϵ turbulence model is applied to simulate this problem. All simulations are performed for plain tube and nine different CCTA geometries in the range of width ratio (b/w) from 0.7 to 0.9, length ratio (s/w) from 2 to 2.5, Reynolds numbers in the range of 5000 to 15,000 and volume fraction of nanoparticles from 0 to 1.5%. The calculated results indicate that the swirl flow created by CCTA is transferred from the tube core to the near wall regions. This results in higher fluid mixing, which enhances heat... 

This paper aims to give a comprehensive atomistic modeling of the nanomechanical behavior of actin monomer. Actin is a ubiquitous and essential component of cytoskeleton which forms many different cellular structures. Despite for several years great effort has been devoted to the investigation of mechanical properties of the actin filament, studies on the nanomechanical behavior of actin monomer are still lacking. These scales are, however, important for a complete understanding of the role of actin as an important component in the cytoskeleton structure. Based on the accuracy of atomistic modeling methods such as molecular dynamics simulations, steered molecular dynamics method is performed... 

The hospital location and service allocation is one of the most important aspects of healthcare systems. Due to lack of studies on covering location-allocation and scheduling problems with respect to the uncertain budget, this paper develops a bi-objective hybrid model to locate hospitals and allocate machines and services scheduled. The costs of establishing facilities are assumed to be uncertain, while a robust counterpart model is employed to overcome the uncertainty. Covering the demand of each service is limited as well. Moreover, hospitals have a limited space to the specialized equipment like CT scan and MRI machines, while there is a cost constraint on hospitals and the specialized...