Showing papers by "Azarbaijan Shahid Madani University published in 2022"

An analytical framework based on the recency, frequency, and monetary model and time series clustering techniques for dynamic segmentation

Abstract: Nowadays, banks use data mining and business intelligence tools and techniques to analyze their customers’ behavior. Customer segmentation is a widely adopted analytical tool to identify distinct groups of customers. Most studies have adopted a static segmentation approach, leading to missing important trends and patterns. In this study, we propose a framework that represents each customer behavior as a time-series sequence of the Recency, Frequency, and Monetary variables, and then exploits time-series clustering algorithms to carry out customer segmentation. The framework consists of state-of-the-art clustering algorithms, including hierarchical, spectral, and k -shape algorithms to divide customers into homogeneous groups and implement point of sale devices transaction data of grocery and appliance retailers. We divide customers into four segments, analyze the behavioral trends, and provide marketing suggestions for each segment. Our results show that, in terms of the computed validity indices, the best clustering model for grocery retailers is reached using hierarchical clustering with the Complexity-Invariant Distance measure, and for appliance retailers, the best segmentation is achieved by applying the spectral clustering with the Complexity-Invariant Distance measure. • A framework that represents each customer behavior as time-series data is proposed. • Hierarchical, spectral, and k -shape clustering are adapted for time series data. • An implementation of the proposed framework using real data is conducted. • Best results are obtained using Complexity-Invariant Distance (CID) measure. • Visualization of results is provided.

Role of geometrically necessary dislocations on mechanical properties of friction stir welded single-phase copper with medium stacking fault energy

Abstract: The contribution of geometrically necessary dislocations (GNDs) and grain boundaries (GBs) on the mechanical properties of different zones in a friction stir welded pure copper joint is unveiled. This representative and simple medium stacking fault metal is selected to decouple the contributions of complex microstructure (precipitates, second phases and phase transformation) and focus only on GNDs and GBs. The GNDs density is much higher in the weld compared to the base material but similar in the thermomechanically affected zone (TMAZ) and the stir zone (SZ). Their difference is rather related to the dislocation distribution: in the grain interior in the SZ and near the GBs and grain interior in the TMAZ. In comparison to the TMAZ, the higher strength and elongation of the SZ results from the formation of finer grains and sharp-clean grain boundaries issued from continuous dynamic recrystallization.

The heterostructure of ceria and hybrid transition metal oxides with high electrocatalytic performance for water splitting and enzyme-free glucose detection

Abstract: Metal oxide nanoparticles have always been promising candidates for important catalytic processes such as water splitting and glucose detection. Herein, the electrocatalytic activity of CeO2/CuO/Co3O4 heterostructure is compared with CeO2/CuO and single ceria nanostructures in water splitting and glucose sensing processes. The CeO2/CuO/Co3O4 and CeO2/CuO heterostructures are synthesized using co-precipitation method and calcination at 650 °C. The obtained nanostructures are studied by several techniques. The CeO2/CuO/Co3O4 nanoparticles exhibit an excellent catalytic performance in alkaline OER and especially HER such that the overpotential is 110 mV vs. RHE for HER and 520 mV for OER deliver a current density of 10 mA cm−2, which is very low in the comparison of CeO2/CuO and single CeO2. In a summary, the low Tafel slope, significant reduction in semicircular diameter in Nyquist plots and high stability of CeO2/CuO/Co3O4 for a long time under bulk electrolysis in HER and OER confirm an enhancement in electrical transport, low charge transfer resistance and high durability of the electrocatalyst during water splitting. In addition, glucose sensing properties of the electrocatalysts was investigated. No significant sensitivity for glucose is seen in the presence of single ceria, but the modified electrodes by CeO2/CuO/Co3O4 and CeO2/CuO exhibit high sensitivity (70.90 and 184.4 μA mM−1cm−2), a low limit of detection (0.74 and 0.83 μM), a linear range (3–12 mM), and a short-response time (3 s), along with excellent selectivity, stability, and applicability for glucose detection in real analyte.

Co-Evolutionary Multi-Swarm PSO Based Optimal Placement of Miscellaneous DGs in a Real Electricity Grids Regarding Uncertainties

Abstract: Distributed generators (DGs) facilitate minimizing a monetary objective for controlling overload or low-voltage obstacles. In conjunction with controlling such complications, a DG unit can be allocated for maximum reliability or efficiency. This study presents a new method based on a new index for locating and sizing DGs in electricity distribution systems. Stable node voltages which are known as power stability index (PSI) are considered in developing the index. An analytical method is applied in visualizing the effect of DG on losses, voltage profile, and voltage stability of the system. In this study, a new approach using co-evolutionary multi-swarm particle swarm optimization (CMPSO) algorithm is purposed for locating DGs in radial electrical distribution systems considering the uncertainty of solar power as well as load and wind power. In this paper, the optimal locations and sizes of DG units are calculated by considering the active power loss, reliability index, and PSI as objective functions. The presented algorithm is tested on 33-bus and 274-bus real distribution networks. The results of the simulation show the effectiveness of the proposed method.

Preparation of a New Sol-Gel Molecularly Imprinted Polymer with Isatin Template for an On-Line SolidPhase Extraction of HMF from Fruit Juice Samples

Abstract: 5-hydroxymethylfurfural (HMF) is an aromatic compound that is an admitted indicator of reduced quality in different foodstuffs. Here, a novel, sensitive, and simple online solid-phase extraction (SPE) based on a molecularly imprinted sol-gel polymer (MIS) coupled to an HPLC-UV was designed and developed for the extraction and determination of HMF. Under optimum conditions, good linearity was achieved from 0.03 to 0.45 μg ml-1 with relative standard deviations (RSDs) below 5.17%. The Limit of detection (LOD) was 0.023 μg ml-1, and the recoveries of spiked real samples were more than 97%. The experimental results demonstrated that the proposed procedure is not to be affected by the matrix interfaces and can be successfully utilized for the routine analysis of HMF in different samples.

On the Temperature Indices of Molecular Structures of Some Networks

Abstract: The topological index is a molecular predictor that is commonly supported in the research of QSAR of pharmaceuticals to numerically quantify their molecular features. Theoretical and statistical study of drug-like compounds improves the drug design and finding work-flow by rationalizing lead detection, instant decision, and mechanism of action comprehension. Using molecular structure characterization and edge segmentation technique, we computed the general temperature topological indices for OTIS networks.

Dominated GSO algorithm for optimal scheduling of renewable microgrids with penetration of electric vehicles and energy storages considering DRP

Abstract: With the growth of distributed energy resources, the development of storage systems technology and an increase in the application of electric vehicles (EV), the energy management of these kinds of sources needs additional research. The task of the distribution network operator is to optimise the microgrid operation at the lowest operating cost. This paper suggests a novel concept for parallel scheduling of EVs and battery storage while considering demand response programme (DRP) to minimise total operating costs. The influence of cooperation of DRP and optimal scheduling of EVs and energy storages on the operating costs, power transaction with upstream grid, hourly DERs, and systems’ technical features, such as voltage profile and power loss, have been studied. Numerical results obtained from an illustrative case study elucidate that the proposed model reduces 5.62 per cent from total power loss and improves the minimum voltage from 0.91 to 0.94 p.u.

Some Fractional Mathematical Models of the COVID-19 Outbreak

Abstract: One of the powerful tools in studying the outbreak of pandemic diseases and providing the necessary predictions is to provide the mathematical model for the spread of these diseases. COVID-19 is a global pandemic that has severely affected the economies of countries and the daily lives of people. Using three mathematical models that are an extension of the classical SIR model, we model the spread of COVID-19 and predict the outbreak of this disease. The first model is the fractional SEIR model in which an exposed group is added to SIR model and we improve this model by adding daily birth and mortality. Using this model, we present a numerical simulation for the spread of COVID-19 in Iran and the world. The second model is a fractional SEIARW model in which we add three groups of exposed and asymptomatic individuals and a virus repository to classic SIR Model. Also to increase the efficiency of this model in simulating the release of COVID-19, we add to it the natural birth and death rate. The third model is a fractional SIRD model in which the group of deaths due to disease is added to the classical SIR model. Using this model, we simulate the second wave of COVID-19 transmission in Iran, Japan, Romania and Saudi Arabia. In these models we use the Caputo and Caputo-Fabrizio fractional order derivatives and we prove the existence of a solution by fixed point theorems and determine the equilibrium points of the system in each of the models. Also, we determine the reproduction number and calculate the approximate answer of the system using the numerical method. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.

Omnidirectional precoding for massive MIMO with uniform rectangular array in presence of mutual coupling

Abstract: The massive Multiple-Input and Multiple-Output (MIMO) system is one of the technologies in 6-Generation (6G) communication networks. Omnidirectional or broad coverage precoding is used in massive MIMO to broadcast the common signals from public channels to all active and non-active users so that the radiation power of these signals is constant in all spatial directions. On the other hand, in large-scale array antennas, the presence of mutual coupling leads to deteriorating the performance of MIMO systems. In this paper, we propose omnidirectional precoding of the massive MIMO equipped with a Uniform Rectangular Array (URA) in presence of the mutual coupling. In the proposed method, omnidirectional transmission and maximum achievable ergodic rate conditions are developed for the case that mutual coupling exists, then an omnidirectional precoding matrix is designed to satisfy three constraints: 1) Omnidirectional transmission, 2) Equal average power transmission per antenna, and 3) Maximum achievable ergodic rate. For this purpose, we show that an omnidirectional matrix can be reconstructed using a pair of vectors with elements' absolute value equal to one that forms a Complementary Set (CS), and the Complete Complementary Codes (CCC) that satisfied some conditions. The intended CS is selected from the Golay sequence and the intended CCC is obtained by solving a gradient algorithm with projection on the Grassmann and Stiefel manifolds. Simulation results confirm the expected results.

Photo-Plasmonic Effect as the Hot Electron Generation Mechanism

Abstract: Abstract Based on the effective Schrödinger-Poisson model a new physical mechanism for resonant hot-electron generation in half-space metal-vacuum configuration of electron gas with arbitrary degree of degeneracy is proposed. The energy dispersion of undamped plasmons in the coupled Hermitian Schrödinger-Poisson system reveals an exceptional point coinciding the minimum energy of plasmon conduction band. Existence of such exceptional behavior is the well-know character of damped oscillation which in this case refers to resonant wave-particle interactions analogous to the collisionless Landau damping effect. The damped Schrödinger-Poisson system is used to model the collective electron tunneling into the vacuum. The damped plasmons is shown to have full-featured exceptional point energy dispersion phase diagram which can have many interesting technological applications. Depending on the tunneling parameter value, in the damped collective excitation band gap there are resonant energy orbital for which the wave-like growing of collective excitations cancels the damping due the quantum electron tunneling. This important feature is solely due to dual-tone wave-particle oscillation characteristics of the collective excitations in the quantum electron gas which leads to the resonant photo-plasmonic effect, as the plasmonic analog of the well-known photo-electric effect. The few nanometer wavelength high energy collective photo-electrons emanating from the typical metal surfaces lead to a much higher efficiency of plasmonic solar cell devices, as compared to their semiconductor counterparts base on electron-hole excitations at the Fermi energy level. The photo-plasmonic effect may be used to study the quantum electron tunneling and electron spill-out at metallic surfaces.

Effects of combined resistance and interval training in females with nonalcoholic fatty liver disease

Abstract: Abstract Background Nonalcoholic fatty liver disease (NAFLD) describes liver inflammation due to excessive fat accumulation and leading to conditions such as liver failure or cirrhosis. Exercise and physical activity can potentially reduce fat levels in the liver. Also, it is shown that combined resistance and interval training (CRIT) is a stronger stimulation for reducing inflammation, through decreasing body fat. Therefore, this study investigated the effect of CRIT on serum levels of fibroblast growth factor 21, fetuin-A, aspartate aminotransferase, alanine aminotransferase, insulin resistance, and lipid profile in females with nonalcoholic fatty liver disease. Methods Twenty-nine females (age range: 49.92 ± 7.16 years) with NAFLD participated in this study and were randomly divided into CRIT (n = 17) and control (n = 12) groups. The CRIT group did combined body weight resistance and interval exercises for eight weeks (three times a week and 40 minutes per session) with a constant increase in the workload, while the individuals in the control group followed their routine daily activities. Results Eight weeks of CRIT decreased fetuin-A, HOMA-IR, LDL and increased HDL and fibroblast growth factor 21. Levels of liver enzymes such as ALP, ALT and AST were also decreased by eight weeks of CRIT. Conclusion Eight weeks of CRIT improved liver enzymes, body composition, lipid profiles, and the serum levels of two hepatokines (fetuin-A and FGF-21) in inactive obese females with NAFLD. Our findings support the view that CRIT may be an effective non-medical therapeutic strategy to decrease NAFLD risk factors and obesity-induced disorders.

Revivification of rhizobacteria-promoting plant growth for sustainable agricultural development

Abstract: Life development in all figures is dependent on agricultural, food security and soil properties. Soil microbes, synergistic co-evolution with plants and bio-mineralization, demonstrate soil dynamism. The population growth around the world is increasing the demand for agricultural products enormously causing an increase in the application of chemical fertilizers. The use of chemical fertilizers and pesticides is deteriorating soil quality and fecundity in the fields, which in turn is making sustainable agricultural production almost unachievable. Therefore, researchers are now focusing on safer and effective agricultural production. Plant growth promoting rhizobacteria (PGPR) that operate as one co-progression among plants and microorganisms exhibiting synergetic and antagonistic collaborations between the soil and microorganisms is the future. Applying plant growth promoters leads to improving microbial regeneration via direct and indirect strategies such as bio-fertilization, revitalizing root development, rhizoremediation, disease tolerance, and so on. The performance of PGPR varies a lot possibly due to different environmental factors that influence its growth and duplication in plants. These limitations can be managed by applying advanced methods, ideas such as micro-encapsulation and nano-encapsulation along with investigating a multidisciplinary studies that integrate nanotechnology, biotechnology, agro-biotechnology, material science, chemical engineering, merging diverse ecological, practical biological methods, and new formulizations.

Quantum Level Instability of Transverse Excitation in Electron Flow

Abstract: Abstract In current research we use the effective Schrödinger-Poisson model to study a new kind of quantum level instability in an infinite-wall slab electron system. We use the Madelung fluid representation along with the conventional eigenvalue problem techniques in order to solve the linearized coupled differential equations representing the transverse collective linear excitations in the electron gas of arbitrary degree of degeneracy having a constant perpendicular momentum. It is shown that the energy levels of collective electrostatic excitations are doubly quantized due to coupled interactions between single-electron analogous to the classic problem of a particle in a box and collective Langmuir oscillations, which are modulated over single particle quantum state. We also report a new transverse electron slab current plasmon energy level instability caused by the interplay between the wave-like many-electron dispersion and the destabilizing perpendicular electron drift momentum. We further study in detail the parametric dependence of such instability versus different aspects of the quantum system. Such a quantum-level instability may have important applications in characteristic behavior the plasmonic devices and their frequency response. Parametric quantization of drifting electron fluid in a box may also have broad applications in nanoscale quantum device calibration and measurements.

Graphene Oxide Derivatization of Electroless Nickelized Aluminum Surface as a Novel Concept in Fabrication of SPME Fiber: Application to HPLC Determination of Some Polycyclic Aromatic Hydrocarbons

Abstract: Abstract In the present study, a SPME fiber coated with a novel material of nickel/graphene oxide nanocomposite has been introduced for the first time. The prepared sorbent was coated onto the surface of an aluminum wire and employed for the extraction and pre-concentration of some Polycyclic Aromatic Hydrocarbons (PAHs), prior to HPLC-UV analysis. The validation parameters of method were attained under optimal conditions. The technique demonstrated good linearity ranges from 0.50 to 140.00 μg L -1 with squared determination coefficients (R 2) more than 0.98 for all target analytes. The Limit of Detection (LOD) and Limit of Quantification (LOQ) of method were in the range of 0.15 μg L-1 to 1.70 and 0.50 μg L-1 to 5.00 μg L-1, respectively. The fiber-to-fiber intra-day and inter-day relative standard deviations were ranges between 1.80% - 6.73% and 3.19% - 8.05%, respectively. The proposed procedure was applied to simultaneous detection and measurement of the selected PAHs in different food samples and proved the effectiveness of method for routine analysis of them. In addition, the good recoveries for the spiking real samples were more than 89%.

CR Maximal Dimensional Submanifolds of Kenmotsu Space Forms

Abstract: For n > 5, we investigate (n + 1)-dimensional contact CR-submanifolds M of (n − 1) contact CR-dimension in a complete simply connected Kenmotsu space form of constant ϕ-holomorphic sectional curvature c which satisfy the condition h(FX,Y ) + h(X,FY ) = 0 for any vector fields X,Y tangent to M, where h and F denote the second fundamental form and a skew-symmetric endomorphism acting on the tangent space of M, respectively.

Aspergillus niger based lipase-tween 80 aggregates as interfacial activated biocatalyst for biodiesel production: Optimization using response surface methodology

Abstract: Biodiesel is a renewable energy source, which is produced through transesterification reactions. Despite great attention to develop enzymatic biodiesel production, there are serious obstacles to the industrial development of it such as its cost and slow reaction rate. Along with disadvantages, there are several advantages for enzymatic biodiesel production. Higher purity of fuel and glycerol is known as the most important achievement of enzymatic process. In this study, performance of four different fungi for lipase production was investigated and Aspergillus niger was selected as enzyme source. Lipase production were optimized using experimental design and the optimized factors were determined as pH 5, temperature 30 °C, Potato Dextrose Broth (PDB) 3 % w/v, olive oil 1.50 % v/v, with maximum lipase activity of 42.8±0.51 U/mg. In order to interfacial activation of the lipase, effect of surfactants was studied. Therefore, surfactant-enzyme aggregates were used as biocatalyst for transesterification reaction. Effects of factors on biodiesel yield were studied too. The yield was 96.41±1.20 % at the optimized conditions (methanol/oil molar ration 5.50:1, enzyme concentration 19 % v/ w, Tween 80 concentration 19 mg L–1, temperature 40 °C and reaction time 46 h).

Plasmonic Dielectric Response of Finite Temperature Electron Gas

Abstract: Abstract In this research we report the dielectric response of a finite temperature electron gas, electrostatically interacting with both external and self-induced plasmonic fields, in the well-known random phase approximation. The generalized energy dispersion relation which incorporates the plasmonic band structure is used to calculate the Lindhard dielectric response of homogenous electron gas from which many important physical functionals, such as the structure factor, loss function, screening potential, optical reflectivity and electronic stopping power are deduced. The present dual length-scale theory of dielectric response incorporates both single electron as well as collective electrostatic oscillation of electrons which, due to the Van-Hove-like singularity at plasmon wavenumber, shows distinct features of plasmonic response to electromagnetic interactions of the electron gas with arbitrary degree of electron degeneracy. It is shown that the static impurity charge screening potential is oscillatory Lennard-Jones-type attractive potential which is quite different from both predicted by the Conventional noninteracting Lindhard theory and the Shukla-Eliasson attractive potential obtained from quantum hydrodynamic approach. It is also revealed that due to resonant electron-plasmon interactions and multi-pole structure of the electronic response function the Landau damping region is scattered. The findings of current research may have important implications for a wide range of physical phenomena relevant to a broad nonrelativistic electron density-temperature regime, from the laboratory scale semiconductors and nanoelectronic technology to the warm dense matter state.