Search

In this paper, the behavior of a natural rubber bearing system (NRBs) equipped with U-shaped dampers is investigated. The U-shaped dampers consist of shaped memory alloy (SMA), structural steel (SS), and combination of both SMA and SS. The combined Mooney-Rivlin and Prony models in ANSYS software is selected for modeling the rubber material. Two cyclic static and dynamic time-history analyses were selected to evaluate the behavior of NRBs equipped with dampers. The results show that the SMA dampers made of FeNiCuAlTaB with 13.5% super-elastic strain and low austenite finish temperature are the most appropriate candidates for use in high shear strain, steel-rubber bearings. The results showed that finite element analyses are able to accurately simulate the mechanical behavior of the damper. Having confirmed the validity of the analysis, the optimum thickness ratio of SMA to SS (tSMA/tSS) to maximize dissipated energy and minimize residual deformation for the dampers was found to be one. The results show that each damper typology has unique benefits; while the U-shaped SMA damper has super-elastic behavior and residual deformation reversibility, the SS dampers significantly increase the energy dissipation capacity. Lastly to illustrate how this could be instrumented on real-world infrastructure, several bridge models, with steel decks and concrete piers isolated by NRBs equipped with steel and SMA dampers, were evaluated.

Based on the random vector ( X + Z , Y + Z ) we study the perturbation C X + Z , Y + Z of the copula C X , Y of the random vector ( X , Y ) when the random noise Z is independent of both X and Y. We also propose a bivariate copula-based modification of the Irwin-Hall distribution and use it to extend the results of Mesiar et al. (2019) and present several examples for illustration.

In this paper, we combine practically verified results from circuit theory with communication-theoretic laws. As a result, we obtain closed-form theoretical expressions linking fundamental system design and environment parameters with the power consumption of analog front ends (AFEs) for communication receivers. This collection of scaling laws and bounds is meant to serve as a theoretical reference for practical low power AFE design. We show how AFE power consumption scales with bandwidth, $\mathit {SNDR}$ , and $\mathit {SIR}$ . We build our analysis based on two well established power consumption studies and show that although they have different design approaches, they lead to the same scaling laws. The obtained scaling laws are subsequently used to derive relations between AFE power consumption and several other important communication system parameters, namely, digital modulation constellation size, symbol error probability, error control coding gain, and coding rate. Such relations, in turn, can be used when deciding which system design strategies to adopt for low-power applications. For instance, we show how AFE power scales with environment parameters if the performance is kept constant and we use these results to illustrate that adapting to fading fluctuations can theoretically reduce AFE power consumption by at least 20x.

Fe-Mn-Al-C austenitic steels have been the subject of intense research because of the promising strength and ductility characteristics of these alloys. Recently, the mechanical properties of this family of materials have been extensively studied; however, limited information regarding their tribological behavior is available in the current literature. This research aims to investigate the wear behavior of Fe-22Mn-10Al-1.4C austenitic steel under different aging conditions. The aging treatments were performed at 500, 550, and 600°C for 1, 2, and 3 h. The microstructural characterizations were performed using optical microscopy (OM) and scanning electron microscopy (SEM) equipped with energy-dispersive spectroscopy (EDS). After homogenizing, the microstructure showed only the austenite phase. The aging treatments resulted in the precipitating of the κ-carbides in the structure. The hardness and wear characteristics of the samples were measured via microhardness and pin-on-reciprocating plate tests, respectively. Results indicated that aging treatments improved the hardness and wear resistance due to the precipitation of κ-carbides up to 62% and 71%, respectively. There was a strong correlation between aging time and tribological behavior such that increasing aging time and temperature resulted in a decrease in the wear rate. Finally, a formula was proposed for predicting the wear behavior of Fe-Mn-Al-C steels at a specific aging temperature.

In this study, an analytical procedure for the bending problem of a viscoelastic sandwich plate with a corrugated core is presented. Reissner–Mindlin plate theory and N-termed Prony series are employed to define the elastic and time-dependent contributions of the governing equations, respectively. Three different corrugation patterns, i.e., rectangular, trapezoidal, and triangular, are examined. Moreover, the structure is analyzed under both simply support and clamp boundary conditions. The calibrated material parameters of polymethyl methacrylate (PMMA) for the Generalized Maxwell rheological model are employed to show the viscoelastic response of the structure. A 3D finite element simulation of the problem is also conducted to confirm the accuracy of the analytical formulation. The two well-known creep and stress relaxation phenomena of the viscoelastic materials are examined for the mentioned corrugation cores and both boundary conditions analytically and numerically. The time-dependent dimensionless deflection and resultant von Mises stress distributions are provided. Besides, the variation of the results with various rise-times and applied load are studied in detail. The von Mises stress contours of the upper surface of the structure at the end of the creep test are also presented. The finite element method outcomes verify the analytical results with excellent compatibility. The proposed analytical procedure can be used as an efficient tool to study the effects of various parameters such as material, geometrical constants, and corrugation pattern on bending of viscoelastic sandwich plates with corrugated core problems for design and optimization, which involves a high number of simulations.

In this research, concurrent employment of Waste Tire Textile Fibres (WTTFs) and lime in two types of low plastic clays (soil A and soil B) is investigated by performing various tests, namely, stan...

Treatment of the industrial wastewater before discharging into aquatic ecosystems using a new technology such as nanotechnology seems necessary. There are different methods for the removal of the heavy metals in the wastewater. In this study, nano-chitin was purchased from the Nano-Novin Polymer Company and used as an adsorbent for the removal of chromium (VI) ions from aqueous solution in a batch system. The effects of pH, temperature, contact time, concentration, and adsorbent dose were investigated. According to the results, the optimum conditions of adsorption occurred at pH = 6, temperature = 25 °C, 60 minutes contact time, and 0.6 g·L−1 adsorbent dose. Investigation of equilibrium isotherms showed that the isotherm fitted the Freundlich model with a correlation coefficient of R2 = 0.9689. The pseudo second-order model with the larger correlation coefficient had a greater fitness against experimental data in the kinetic studies. Thermodynamic parameters such as Gibbs free energy, enthalpy, and entropy were calculated, which indicated spontaneous, endothermic, and random processes, respectively. Given the good results of this project, nano-chitin can be suggested as a novel adsorbent which is highly capable of adsorbing hexavalent chromium from aqueous solutions. Highlights Nano-chitin was purchased from the Nano-Novin Polymer Company.; Nano-chitin as a novel adsorbent is highly capable of adsorbing chromium from aqueous solutions.; The results showed that pH = 6, adsorbent dose of 0.1 g/L, 25 °C and 60-minute contact time were the optimum adsorption values in this research.; The results showed the data better fitted the Freundlich isotherm model and kinetic pseudo-second-order model.

In the present work, a porous carbonaceous platform containing zirconium oxide was used for spreading Ni nanoparticles, and applied to methanol oxidation. The platform was obtained by calcination of a metal-organic framework (MOF) attached to graphene oxide. Nickel nanoparticles were then deposited on the nanocomposite by chemical reduction from a Ni2+ solution. The obtained electrocatalyst was characterized by different methods. An excellent electrocatalytic behavior was observed towards methanol oxidation in alkaline medium (j ~ 240 mA cm−2 or ~ 626 mA mg−1 in 1.0 M methanol). The results of methanol oxidation by various electrochemical studies (cyclic voltammetry, electrochemical impedance spectroscopy, chronoamperometry and chronopotentiometry) revealed the effective synergy between reduced graphene oxide, porous carbon material, ZrO2 metal oxide and Ni nanoparticles. Good durability and stability of the proposed electrocatalyst and significantly increased current density of methanol oxidation suggest it as a potential alternative for Pt-based electrocatalysts in direct methanol fuel cells.

Metal-oxide based gas sensors are widely used as the gas sensing elements in industrial and residential areas. Many efforts have been made to increase sensitivity and reduce the working temperature of metal-oxide based gas sensors. In this paper, ZnO nanowires (NWs) were successfully grown on graphene (Gr) nanosheets by the hydrothermal method. The synthesized Gr/ZnO NWs nanocomposite were investigated as the sensing material. Not only is the sensor response much higher, it also works in a lower working temperature toward a low concentration of ethanol in comparison with pure ZnO NWs. The optimum working temperature is reduced from 200 °C in pure ZnO NWs to 125 in Gr/ZnO NWs sensor. The maximum response of the Gr/ZnO NWs sensor is 26, which is approximately enhanced twice as much as the pure ZnO NWs sensor. The lower limit of detection (LLOD) of the proposed sensor is as low as 1 ppm ethanol vapor. The sensor was shown a high response, good selectivity, fast response toward ethanol vapor, excellent repeatability, and low sensitivity toward a high relative humidity, as well as remarkable long-term stability.

Polya urn models are of the well-known probabilistic concepts and stochastic processes. The proportion of the colors is the question of the most interest in these models. Always, the structure (The...

In this research, the density functional theory (DFT) calculations were carried out for investigation non-bonded interaction between the anticancer drug Fludarabine (Fludara) with sugar molecule (2S,3R,4S,5S)-2-(hydroxymethyl)-3,5-dimethyloxolane-3,4-diol (OXO) by using B3LYP/6-311+G* level of theory in the solvent water. The electronic spectra of the Fludara drug and Fludara/OXO complex in solvent water were calculated by time dependent density functional theory (TD-DFT) for the study of intermolecular interaction effect. The non-bonded interaction effects of the Fludara drug with OXO on the electronic properties, natural charges and chemical shift tensors have been also detected. The results display the change in title parameters after interaction process. According to the natural bond orbital (NBO) results, the Fludara molecule and OXO play as both electron donor and acceptor at the Fludara/OXO complex. On the other hand, the charge transfer is occurred between the bonding, antibonding or nonbonding orbitals in two molecules drug and OXO.

In the current research, effort has been made to gain a deeper understanding regarding the parameters affecting the dynamic behaviour of a sandy soil reinforced by Waste Tire Textile Fibres (WTTFs)...

The aim of this work is a study of the encapsulation and intermolecular non-bonded interaction of an anticancer drug Talzenna into carbon nanotube [CNT(8,8-7)] and boron nitride nanotube [BNNT(8,8-7)]. The interaction effects of Talzenna with the CNT and BNNT on electronic and adsorption properties were theoretically investigated in the solvent phase at the M062X/6-311G* level of theory. With the encapsulation of Talzenna drug, the electronic properties of the CNT and BNNT nanotubes change significantly. The electronic spectra of the Talzenna drug, complexes CNT/Talzenna and BNNT/Talzenna in the solvent water were calculated by Time-Dependent Density Functional Theory (TD-DFT) for the study of adsorption effect. According to the natural bond orbital (NBO) results, all three molecules Talzenna, CNT and BNNT play as electrons donor and acceptors at the complexes CNT/Talzenna and BNNT/Talzenna. On the other hand, the charge transfer is occurred between the bonding, antibonding or nonbonding orbitals in molecules Talzenna, CNT and BNNT. Based on the results, CNT(8,8-7) and BNNT(8,8-7) can be used as a drug delivery system for the transportation of Talzenna as anticancer drug within the biological systems.

Reducing energy consumption in industry, agriculture, and processing industries is important with regard to economical and environmental aspects. The purpose of the present study was to investigate the material and energy flow as well as energy indicators in the production of seven common breads in Iran. The input and output data were collected by questionnaire method and face-to-face interviews with Ilam bakeries in 2020. The energy content of inputs and output materials and the energy indicators were calculated. The total average of energy invested to produce one ton of bread was 22,622.70 MJ, and the output energy was 11,834.89 MJ. The highest output energy belonged to the production of Barbari bread, and the lowest amount was obtained for Sangak bread. The most effective energy consumer input in bread production was wheat flour with a share of 53.57%. The average energy ratio, energy intensity, and net energy gain indicator in bread production were 0.52, 22.62 MJ kg−1, and −10.79 MJ kg−1, respectively. The lowest energy consumption and energy intensity and the highest energy ratio index were related to Rizeshi Nimeh Hajmi bread, and the highest net energy gain was obtained for Barbari bread. Consumption of natural gas in the production of Sangak and Saji bread was higher than other bread types. The obtained findings are benefit results for optimizing the bakery units in point of both energy and material consumption as well as decreasing environmental impacts.

In this brief, an in-phase dual band Filtering Power Divider (FPD) based on terminated coupled lines is proposed. The design equations are developed for the analysis of the proposed power divider and design studies are provided to investigate the proposed design. The prototype dual-band FPD operating at 4.11 and 6.56 GHz with −3 dB fractional bandwidths of 4.13% and 1.22% is simulated, fabricated, and tested. Finally, the measured results show that insertion losses (ILs) are better than 0.8 dB and 1.8 dB at 4.11 GHz and 6.56 GHz, respectively. Also, this FPD has good characteristics such as 22 dB and 17.3 dB input return losses (RLs) and isolation of 17 dB and 26 dB at two passbands. Results indicate that the new FPD exhibits both good isolation and low insertion loss within the two passbands. The two output signals are in-phase across the whole band with less than 0.5° phase difference.

In situations that the predictors are correlated with the error term, we propose a bridge estimator in the two-stage least squares estimation. We apply this estimator to overcome the multicollinearity and sparsity of the explanatory variables, when the endogeneity problem is present.The proposed estimator was applied to modify the Durbin-Wu-Hausman (DWH) test of endogeneity in the presence of multicollinearity. To compare our modified test with the existing DWH for detection of an endogenous problem in multi-collinear data, some numerical assessments are carried out. The numerical results showed that the proposed estimators and the suggested test perform better for the multi-collinear data. Finally, a genetical data set is applied for illustration the our results by estimating the coefficients parameters in the presence of endogeneity and multicollinearity.

Expansive soils are problematic for their relatively low load bearing capacity and extensive swelling-shrinkage deformations. Therefore, treatment of such soils is often considered to be necessary prior to construction. This paper investigates the potential of reusing waste tire textile fibers (WTTFs), a byproduct of the treatment process of end of life tires (ELTs), as reinforcement materials for treatment of expansive soils. To that end, mechanical reinforcement of sodium bentonite by WTTF inclusion has been evaluated through a set of standard compaction, direct shear, Unconfined Compressive Strength (UCS), California Bearing Ratio (CBR), and swelling-consolidation tests. Six different WTTF contents – that is, fc = 0%, 0.5%, 1%, 2%, 3%, and 4% were used and investigated. It was proven that WTTFs can improve the shear strength and UCS parameters. Swelling deformations of the soil were demonstrated to reduce by as much as 44%. At low WTTF contents, CBR was enhanced marginally. However, this parameter decreased at high WTTF contents. Therefore, it can be concluded that WTTFs can be used as economical reinforcement materials in expansive soils to enhance the strength parameters, mitigate the swelling properties, and address an environmental concern regarding WTTFs.

In the current study, the molecular structures of the two new azomethine dyes such as AAFOH-1 and AAFOH-2 have been investigated with the use of density functional theory (DFT/B3LYP/6-311+G(d)) in a DMSO solvent for the first time. The electronic spectra of the new dyes in a DMSO solvent were carried out by temporally dependent density functional theory (TD-DFT) method. The computed absorption spectral data of the investigated molecules are in good agreement with the experimental data, thus allowing an assignment of the UV/Vis spectra. The equilibrium geometry, the HOMO and LUMO molecular orbitals, excitation energies, oscillator strengths and natural bond orbital (NBO) analysis for the molecules have also been calculated and presented. The electron location function (ELF), localized orbital locator (LOL), and quantum theory of atoms in molecules (QTAIM) analyses were also carried out. On the basis of polyvinyl alcohol (PVA) and the new synthesized azomethine dyes polarizing films were developed. The main optical parameters of polarizing PVA-films (transmittance, polarization efficiency, and dichroic ratio) have been measured and discussed. Anizotropy of thermal conductivity of the PVA-films have been studied.

The increase in the level of awareness and knowledge of public officials and senior managers of the community about the need to formulate an appropriate public cultural policy indicates its role and importance in improving social life. This research was established with the main objective of identifying the components of the implementation of cultural policies. The descriptive survey was used methodologically and the data collection instrument was a questionnaire with the statistical population, including experts, which was carried out using the two-step Delphi method. The statistical population of experts included cultural managers and university professors in the field of management and policy formulation. The sampling was non-random and deliberate, with 7 interviews carried out. Based on Delphi's two-stage results, panel member consensus, and achievement of theoretical saturation, experts identified 44 components. In conclusion, the results also showed that the dimensions of "management factors" and "software" had the highest average and the dimensions of "structural factors" and "activation of cultural centers in the university" had the lowest range.

In the Hamadan region, Sanandaj-Sirjan Zone (SaSiZ), W Iran, a pegmatite-aplite vein occurs that contains up to 15 vol% sapphire. The Hamadan sapphire is black to blue, and translucent to opaque, which reveals its semi-gem and gem quality. On the basis of petrographic studies, the Hamadan sapphire-bearing pegmatite-aplite vein represents alkali syenitic to syenitic composition and its adjacent granitoids have a range of composition from syenitic to quartz monzonite and granodiorite. New petrographic, whole-rock geochemical data and δ18O values [9.30–12.45‰VSMOW (Vienna Standard Mean Ocean Water)] suggest crustal origin for the peraluminous, S-type and alkaline sapphire-bearing pegmatite-aplite vein. The presence of syngenetic quartz inclusions in the sapphire, and some similar physical-gemological signatures (e.g., parting patterns and angles) of the Hamadan sapphire and kyanite support the generation of the sapphire at the expense of kyanite. In addition, a secondary metasomatic stage may have played a minor role in formation of the sapphire grains. The results indicate an important role for the mafic magmas in triggering crustal anatexis and gem crystallization in continental subduction zone settings.

A repeatable method was introduced for developing liable flat sheet thin-film forward osmosis (FO) membranes on spacer backing fabric support. Pasting of a water-soluble polymer (Polyvinylpyrrolidone (PVP)) on the backside of the fabric was investigated to prevent the penetration of the polymer dope (Polyethersulfone (PES)) into the backing fabric during phase inversion. All samples were prepared on spacer fabric with a 250 μm in thickness. First, PVP as a water-soluble polymer was cast in 100 μm thickness on a glass plate and then the spacer fabric was pulled from the top on the pasted PVP to fill the bottom side of the fabric. The lower bottom side of the fabric was filled with PVP. This helped to limit PES polymer penetration and to achieve a thinner polymeric support layer during phase inversion. After interfacial polymerization and forming rejection, thin-film composite (TFC) FO membranes were obtained. Water flux of 17.1 Lm−2h−1 and reverse solute flux (RSF) of 9.2 g m−2h−1 were achieved when 1 M NaCl as draw solution and deionized water as feed solution (FS) were used under pressure retarded osmosis (PRO) operating mode for TFC2 sample.

In this work, we propose an extension of the Irwin–Hall distribution to obtain the distribution of sum X + Y when the random variables X, Y are connected by a copula C X , Y . Assuming that C X , Y...

In this paper, an analytical approach is proposed to examine the finite strain time-dependent behavior of incompressible, isotropic visco-hyperelastic elastomeric material under bending. Phenomenological hyperelastic invariant-based strain energy density function, Yeoh model, and N-termed Prony series are utilized to define the strain-dependent and time-dependent parts of the visco-hyperelastic constitutive model, respectively. 3D finite element analysis of the problem is carried out using ABAQUS/Visco to verify the analytical solution results. Material parameters of polyurea are calibrated using an optimization framework for experimental results under five different strain rates, simultaneously. Two well-known tests of viscoelastic materials, stress relaxation and creep tests, are investigated both analytically and numerically. Distribution of the Cauchy stress components and the resultant bending moment versus time, and the variation of the mentioned results with different rise times and ultimate bent angles are provided for the stress relaxation test. Moreover, the strain and bending angle results are plotted in a creep test for different rise times and applied moments. Besides, a multi-step relaxation test and creep recovery test are performed for different loading conditions. Finite element method results confirm the analytical approach with great compatibility.

The hypothesis that petrochemical oily wastewater containing high amounts of total dissolved solids (TDS), chemical oxygen demand (COD) and total organic carbon (TOC) can be effectively treated by a new biomimetic forward osmosis (FO) membrane for fertigation purposes was assessed. The biomimetic FO membrane was characterized, and its intrinsic properties were evaluated. The fertilizer-driven FO (FDFO) process was evaluated in terms of water flux (WF), reverse solute flux (RSF), specific RSF (SRSF), and oil rejection at various draw solution (DS) concentrations and cross-flow velocities. Under optimized conditions, deionized water was used as feed and 3 M KCl, the most widely used potassium fertilizer, was used as DS at a cross-flow velocity of 0.1 m·s−1. WF and RSF of 67.22 Lm-2 h−1 and 48.3 gm−2 h−1, respectively, were obtained. Using saline oily wastewater as the feed, the orientation of the feed facing the membrane support layer exhibited a lower WF due to oily layer fouling within the membrane support. Apart from almost complete rejections of organic chemicals, the biomimetic FO membrane demonstrated a better performance (WF = 11.31 Lm−2 h−1) than the typical polyamide thin film composite (TFC) membrane (WF = 5.23 Lm−2 h−1) during mid-term fouling tests. This study demonstrates that FO process is an effective strategy for sustainable management of hazardous petrochemical oily wastewater by recycling the diluted fertilizer solution for direct fertigation without further treatment.

In this article, a novel multistage CLEAN-based method based on generalized likelihood ratio test (GLRT) is proposed for scattering centers’ enumeration and their parameter estimation. To analyze the performance of the proposed scattering center enumeration algorithm, the probability density function (pdf) of the GLRT is derived for both the known noise variance case and the unknown noise variance case. In addition, we derived a closed form for the probability of correct enumeration of scattering centers, obtained in the case of the known model parameter. A method to reduce the computational complexity of the proposed algorithm has also been introduced. Despite the conventional methods which are based on the damped exponential models, the proposed method uses the geometrical theory of diffraction (GTD) model whose performance does not degrade as the bandwidth increases. The simulation results show an appropriate performance of this method at low signal-to-noise ratio (SNR) situations.

The neural system is a multifunctional perceptual learning system. Our brain can perceive different kinds of information to form senses, including touch, sight, hearing, and so on. Mimicking such perceptual learning systems is critical for neuromorphic platform applications. Here, an artificial tactile perceptual neuron is realized by utilizing electronic skins (E-skin) with oxide neuromorphic transistors, and this artificial tactile perceptual neuron successfully simulates biological tactile afferent nerves. First, the E-skin device is constructed using microstructured polydimethylsiloxane membranes coated with Ag/indium tin oxide (ITO) layers, exhibiting good sensitivities of ∼2.1 kPa-1 and fast response time of tens of milliseconds. Then, the chitosan-based electrolyte-gated ITO neuromorphic transistor is fabricated and exhibits high performance and synaptic responses. Finally, the integrated artificial tactile perceptual neuron demonstrates pressure excitatory postsynaptic current and paired-pulse facilitation. The artificial tactile perceptual neuron is featured with low energy consumption as low as ∼0.7 nJ. Moreover, it can mimic acute and chronic pain and nociceptive characteristics of allodynia and hyperalgesia in biological nociceptors. Interestingly, the artificial tactile perceptual neuron can employ "Morse code" pressure-interpreting scheme. This simple and low-cost approach has excellent potential for applications including but not limited to intelligent humanoid robots and replacement neuroprosthetics.

Heavy metal wastes generated from mining activities are a major concern in developing countries such as Iran. Increasing concentrations of these metals in the soil make up a severe health hazard due to their non-degradability and toxicity. In this study, batch washing experiments were conducted in order to investigate the removal efficiency of zinc by biodegradable chelates, tartaric acid. For this purpose, soil samples were collected from the zinc contaminated soil in the region of the Angouran, Zanjan, Iran. Hence, optimization of batch washing conditions followed using a three-level central composite design approach based on the response surface methodology. The results demonstrated that the effects of pH, tartaric acid concentration, and interaction between selective factors on the zinc removal efficiency were all positive and significant (P −1, pH of 4.46, and incubation time of 120 min as the optimal conditions. Accordingly, response surface methodology is appropriately capable to determine and optimize chemical soil washing process to remediate heavy metal polluted soil.

In this study, the critical nugget size, at which the failure state in tensile shear test changed from the interfacial failure mode to the pull-out failure one, was estimated as a function of nugge...

The behavior of natural rubber bearing incorporated with high toughness steel ring dampers (NRB-HTSRDs) is presented. These dampers are made of several steel rings, which are connected by weld in different configurations around the rubber bearing. The operational characteristics of this system including effective horizontal stiffness, secondary hardening, system stability, energy dissipation, equivalent viscous damping, and residual deformation were studied. The results showed that the energy dissipation in these dampers; is mainly revealed as yielding due to flexural deformation of the rings. All specimens of NRB-HTSRDs system; overally enhance the behavior and are considerably better than natural rubber bearing (NRB) or high damping rubber bearing (HDRB). The arrangement of HTSRD2, HTSRD4 and HTSRD6 have better behavior rather than HTSRD1, HTSRD3 and HTSRD5 due to modest initial stiffness at lower shear strains to control small lateral loads of the structure and undesirable effects on the flexibility of rubber bearing, and higher secondary hardening in larger shear strains that increases the energy dissipation and stability of the structure. Also, the specimens in which the rings have larger diameter and are only connected to the top and bottom plates, dissipate energy better than other specimens.

Various methods have been proposed for passive localization by using a network of sensors measuring different parameters such as the angle of arrival (AOA), time difference of arrival (TDOA), Doppler frequency difference of arrival (FDOA), differential received signal strength (DRSS), the gain ratio of arrival (GROA), or a combination of these pieces of information. In this paper, a method for target localization based on power of received signal in multiple stations has been proposed for two scenarios. In one scenario, the receiving antennas are omnidirectional and in the other scenario they are directional. We have derived a closed-form solution for source localization in the first scenario and we have proposed two methods (i.e., random search and Taylor series) for estimating the target location in the second scenario. Using computer simulations, the performance of our methods was compared with the Cramer–Rao lower bound (CRLB) and it was shown that the proposed scheme outperforms conventional AOA-only measurement methods. Also, the effect of estimation error of parameter $n$ (which is related to the signal propagation path-loss exponent in the environment) on the performance of the proposed method was analyzed and it was concluded that it has no significant influence on the performance of the proposed method. Finally, the performance of the proposed method has been evaluated using the real received signal strength (RSS) data.

While chlorination is critical for water disinfection, a knowledge gap includes the nature of free residual chlorine (FRC) decay, which was investigated using four physical methods (SSA, SSR with a...

In this brief, we present a novel ultra-wide stopband compact microstrip bandpass filter (BPF) with low insertion loss and compact size. The proposed filter is designed based on two five-stage stepped impedance resonators (SIRs) which are capacitively coupled to each other’s. The five-stage SIRs can be used to have miniaturized size as well as suppression of harmonics. In this BPF, by increasing stages of SIRs, multiple transmission zeros are generated. Therefore, a compact BPF with a ultra-wide stopband could be achieved. The bandpass region of the proposed filter is extended from 3.58 GHz up to 10.31 GHz with insertion loss lower than 0.42 dB. The rejection level is better than −26 dB from 11.25 GHz up to 30 GHz and better than −17.5 dB up to 100 GHz. The center frequency of the proposed BPF is located at 6.95 GHz with −3 dB fractional bandwidth (FBW) of 97%. The dimension of the fabricated filter is $0.128\,\,{\lambda }_{\textbf {g}}{\times }{0.378}\,\,{\lambda }_{\textbf {g}}$ . The simulation results are verified by fabrication and measurement up to 30 GHz that there is a good agreement between them.

Three-dimensional flexible porous conductors have significantly advanced wearable sensors and stretchable devices because of their specific high surface area. Dip coating of porous polymers with graphene is a facile, low cost, and scalable approach to integrate conductive layers with the flexible polymer substrate platforms; however, the products often suffer from nanoparticle delamination and overtime decay. Here, a fabrication scheme based on accessible methods and safe materials is introduced to surface-dope porous silicone sensors with graphene nanoplatelets. The sensors are internally shaped with ordered, interconnected, and tortuous internal geometries (i.e., triply periodic minimal surfaces) using fused deposition modeling (FDM) 3D-printed sacrificial molds. The molds were dip coated to transfer-embed graphene onto the silicone rubber (SR) surface. The presented procedure exhibited a stable coating on the porous silicone samples with long-term electrical resistance durability over ∼12 months period and high resistance against harsh conditions (exposure to organic solvents). Besides, the sensors retained conductivity upon severe compressive deformations (over 75% compressive strain) with high strain-recoverability and behaved robustly in response to cyclic deformations (over 400 cycles), temperature, and humidity. The sensors exhibited a gauge factor as high as 10 within the compressive strain range of 2-10%. Given the tunable sensitivity, the engineered biocompatible and flexible devices captured movements as rigorous as walking and running to the small deformations resulted by human pulse.

Frequency division duplex (FDD) massive multiple-input multiple-output (MIMO) systems introduce a large overhead in downlink channel estimation in contrast to the time division duplex (TDD) mode. This overhead results in a considerable spectral efficiency (SE) gap between the FDD and TDD modes. In this paper, we consider the performance of the TDD and FDD massive MIMO systems with a spatially correlated channel in the presence of jamming in the network. We show how a smart jammer can effectively design its attack signal to degrade the network performance in terms of the downlink SE. Since the jammer can obtain different information about the channels in the TDD and FDD modes, two distinct jamming strategies are proposed for each mode. In the numerical results, the performance of both the TDD and FDD modes under the optimized jamming designs are evaluated and compared. Our results show that despite more attention to the TDD mode in current massive MIMO systems, it is more vulnerable to smart jamming attacks compared to the FDD mode which results in a smaller SE-gap between the modes. Furthermore, a countermeasure technique is proposed to combat this jamming attack in both the TDD and FDD modes by estimating the jamming power, grouping users, and allocating power among them. The numerical results demonstrate the effectiveness of the proposed countermeasure techniques in both the TDD and FDD modes.

In this work, the influences of thermal annealing and chemical passivation on the optical and electrical properties of ultraviolet light-emitting-diode (UV-LED) were investigated. The electroluminescence (EL) intensities of the LEDs under KOH treatment and thermal annealing increased by 48% and 81%, respectively compared to as-fabricated LED under current level of 10 mA. Cathodoluminescence (CL) mapping of UV-LEDs confirmed no variation of the density of the non-radiative recombination centers after surface treatments, and no obvious change in surface morphology was identified due to lacking of energy for surface atom migration. However, Raman spectroscopy indicates a relaxation of compressive strains inside the thin film after both thermal and chemical treatments, and conductive atomic force microscopy (c-AFM) also illustrated reduced leakage current after KOH passivation, which are responsible for the improved luminescence properties of UV-LEDs.

In the present work, the adsorption of the molecule cytosine on carbon nanotube [CNT] (6,6-6) was investigated for the first time using density functional theory (DFT) calculations in the gas phase. The non-bonded interaction effect of compounds cytosine and CNT(6,6-6) nanotube on the electronic properties, chemical shift tensors and natural charge was investigated. The electronic properties of the obtained complex change after cytosine adsorption. The natural charge analysis showed that the charge transfer occurs between cytosine and CNT(6,6-6) nanotube and it was induced the dipole moment to the CNT(6,6-6) nanotube. Moreover, the formation of an intermolecular hydrogen bond between cytosine and CNT(6,6-6) nanotube has been investigated. The electronic spectra of the isolated molecule cytosine and the complex CNT(6,6-6)/cytosine in the gas phase were calculated by time dependent density functional theory (TD-DFT). The various parameters such as equilibrium geometry, the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO) of the cytosine and CNT(6,6-6) nanotube were calculated and discussed consequently.

Cancer is one of the leading causes of death worldwide, affecting millions of people every year. While chemotherapy remains one of the most common cancer treatments in the world, the severe side effects of chemotherapy drugs impose serious concerns to cancer patients. In many cases, the chemotherapy can be localized to maximize the drug effects; however, the drug systemic circulation induces undesirable side effects. Here, we have developed a highly efficient cellulose-based nanoadsorbent that can capture more than 6000 mg of doxorubicin (DOX), one of the most widely used chemotherapy drugs, per gram of the adsorbent at physiological conditions. Such drug capture capacity is more than 3200% higher than other nanoadsorbents, such as DNA-based platforms. We show how anionic hairy cellulose nanocrystals, also known as electrosterically stabilized nanocrystalline cellulose (ENCC), bind to positively charged drugs in human serum and capture DOX immediately without imposing any cytotoxicity and hemolytic effects. We elucidate how ENCC provides a remarkable platform for biodetoxification at varying pH, ionic strength, ion type, and protein concentration. The outcome of this research may pave the way for developing the next generation in vitro and in vivo drug capture additives and devices.

Background COVID-19 pandemic imposed a lockdown situation to the world these past months. Researchers and scientists around the globe faced serious efforts from its detection to its treatment. Methods Pathogenic laboratory testing is the gold standard but it is time-consuming. Lung CT-scans and X-rays are other common methods applied by researchers to detect COVID-19 positive cases. In this paper, we propose a deep learning neural network-based model as an alternative fast screening method that can be used for detecting the COVID-19 cases by analyzing CT-scans. Results Applying the proposed method on a publicly available dataset collected of positive and negative cases showed its ability on distinguishing them by analyzing each individual CT image. The effect of different parameters on the performance of the proposed model was studied and tabulated. By selecting random train and test images, the overall accuracy and ROC-AUC of the proposed model can easily exceed 95% and 90%, respectively, without any image pre-selecting or preprocessing.

In this work, we use a copula-based approach to select the most important features for a random forest classification. Based on associated copulas between these features, we carry out this feature selection. We then embed the selected features to a random forest algorithm to classify a label-valued outcome. Our algorithm enables us to select the most relevant features when the features are not necessarily connected by a linear function, also, we can stop the classification when we reach the desired level of accuracy. We apply this method on a simulation study as well as a real dataset of COVID-19 and for a diabetes dataset.

This Letter presents a dual-band filtering power divider (FPD) by employing square-loop resonator loaded by open stubs. The even- and odd-mode equivalent circuits of the proposed resonator are analysed and design equations are derived. For demonstration, the power divider (PD) is fabricated and measured. The simulated results of the PD not only show a good selectivity but also it does good isolation. Finally, the comparisons of the measured and simulated results of the dual-band FPD are presented, which are in good agreement. The measured results show that the dual-band FPD has better than -30/-36 dB isolation, -16.5/-18 dB return loss, and -3.9/-4.0 dB insertion loss at centre frequencies of 3.1 and 5.3 GHz, respectively.

The main purpose of this study is a better comprehension of the non-bonded interaction between an anticancer drug Ciclopirox and carbon nanotube [CNT(6,6-6)]. The electronic structure and adsorption properties of the molecule Ciclopirox over the surface of CNT were theoretically studied in the solvent phase at the B3LYP/6-31G* level of theory for the first time. The electronic spectra of the Ciclopirox drug, CNT(6,6-6) and complex CNT(6,6-6)/Ciclopirox in solvent water were calculated by time dependent density functional theory (TD-DFT) for the investigation of adsorption effect. The non-bonded interaction effects of the Ciclopirox drug with CNT(6,6-6) on the chemical shift tensors and natural charge have been also detected. According to the natural bond orbital (NBO) results, the molecule Ciclopirox and CNT(6,6-6) play as both electron donor and acceptor at the complex CNT(6,6-6)/Ciclopirox. On the other hand, the charge transfer is occurred between the bonding, antibonding or nonbonding orbitals in two molecules drug and CNT. As a consequence, CNT(6,6-6) can be considered as a drug delivery system for the transportation of Ciclopirox as anticancer drug within the biological systems.

Performance of inline coagulation-microfiltration (IMF) process for treatment of oily wastewater using a newly developed kaolinitic clay-Based ceramic membrane was investigated. Ceramic microfiltration (MF) membrane was fabricated utilizing kaolinitic clay as starting material and polyvinyl alcohol (PVA) as binder followed by characterizing employing Differential thermal analysis/Thermo-gravimetric (DTA/TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses. The efficiency of adding Al2 (SO4)3 as the prime coagulant for IMF of oily wastewater was assessed and modeled utilizing response surface methodology (RSM) based on Box-Behnken design (BBD). Moreover, the performance of long-term process was evaluated through periodic backwashing mode at the optimum condition within 17 cycles (90 min) including 240 s of forward filtration, backwashing for 15 s with 5 s of rest between each cycle. The results exhibited that water flux and rejection can be correlated with the input variables by the models with 2.29% and 1.67% relative deviation, respectively. The analysis of variance (ANOVA) results, which was employed to optimize the experiment input condition were as pH = 7.2, FC = 921 mg. L−1 and CC = 207 mg. L−1 and the corresponded responses after 90 min were water flux = 123.85 L m−2 h−1 (LMH) and rejection = 97.31%. The results of periodic backwashing showed that water flux could be intensified as 1.68 times compared to continuous forward IMF mode, while the oil rejection is equal to 98.06%. The overall results showed that the IMF system could be considered as a promising system for membrane fouling mitigation and filtration performance intensification.

Internet of Things (IoT) as a new technological revolution has been proposed recently wherein the things are connected over the Internet. Because of the inherent characteristics of IoT for storage of data at untrusted and heterogeneous hosts, data replication across large geographic distances for efficient data management is unavoidable. The selection of appropriate replication things in the IoT, which reduces response time and cost is one of the most important issues of data management. Since this problem is an NP-hard problem, classic approaches are not efficient to solve this issue, and evolutionary algorithm such as ant colony optimisation (ACO) and genetic algorithm (GA) seems to be very useful. This study offers a method based on a combination of ACO and a GA to solve this problem. In the proposed method, the ACO has been used to create diversity, and afterwards, the GA is performed to provide a full search over the search space. The obtained results have shown the better performance of the proposed method in comparison with ACO, the High-QoS First-Replication (HQFR), and the Response Time-based Replica Management algorithms with regard to waiting time. In addition, the obtained results have revealed the better performance of the hybrid method in comparison with HQFR and the Dynamic Cost-aware Re-replication and Re-balancing Strategy.

The present paper is aimed to investigate the behavior of Natural Rubber Bearing incorporated with steel ring damper (NRB-SRD). These types of dampers are integrated of several steel rings which are considered with two configurations namely, continual steel ring damper and separate steel ring damper and are inserted between top and bottom plates. The performance characteristics of the system such as effective horizontal stiffness, energy dissipation, equivalent viscous damping and residual deformation are calculated and then compared with the results of high damping rubber bearings and also shape memory alloy (SMA)-lead core rubber bearing (SMA-LRB). The results show that the energy dissipation in steel rings are mainly based on plastic deformation due to flexural behavior of the rings. NRB-SRD shows better performance in energy dissipation comparing to SMA-LRB and HDRB. These additional dampers show higher stability and energy dissipation in low shear strains due to developing of link between structure and substructure having desirable initial stiffness under weak earthquakes and wind loads and also in higher shear strains due to creation of higher energy dissipation, stability and secondary stiffening.

Nitride semiconductors have become the new generation of light sources for displays and optical storage. Nitride emitters are highly efficient, environmentally friendly and have a long device life. In this article, we have designed a new structure for ultraviolet light-emitting diode. The device consists of AlGaN/GaN/InGaN multi-quantum well structure. In this design, the quantum structure was engineered to increase the confinements of carriers in the quantum well. The more carrier’s confinement increases radiative recombination rate in the active region of the device and enhances the device performance. The proposed design and its performance are simulated and studied by numerical approach. Comparing to reported design, significant improvement in the intensity of output light and reduced electrical power consumption has been observed and the structure shows better performance at wavelength of 350–380 nm.

Aqueous micro/nanogel suspensions remain difficult to sterilize, store, and ship. Current techniques such as freeze-drying and spray-drying have noticeably failed to preserve the structure of gel p...

The palladium (Pd)/tin oxide (SnO2)/porous graphitic carbon nitride (g-C3N4) nanocomposites with different Pd and g-C3N4 contents were synthesized by a facile hydrothermal route and their applications as efficient carbon monoxide (CO) gas sensors were investigated. These nanocomposites were characterized in detail by X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), micrograph techniques (FESEM and TEM), and energy dispersive X-ray spectroscopy (EDS), in order to evaluate their structural and morphological properties. On the basis of the FESEM and TEM analysis, two-dimensional porous g-C3N4 nanosheets provided a large surface area suitable for growth of SnO2 nanoparticles and formation of a heterogeneous nanocomposite. Among different weight ratios of the components of Pd/SnO2/g-C3N4 nanocomposites, 5%Pd/SnO2/5%g-C3N4 exhibited excellent CO sensing characteristics such as high response, short response/recovery times, good selectivity and stability at lower operating temperature of 125 °C. The outstanding gas sensing performance of these nanocomposites could be attributed to the high surface area of porous g-C3N4, the strong spillover effect of Pd nanoparticles as well as the formation of g-C3N4/SnO2 heterojunction.

In this study, the antioxidant property of new synthesized azomethins has been investigated as theoretical and experimental. Methods and Results: Density functional theory (DFT) was employed to investigate the Bond Dissociation Enthalpy (BDE), Mulliken Charges, NBO analysis, Ionization Potential (IP), Electron Affinities (EA), HOMO and LUMO energies, Hardness (η), Softness (S), Electronegativity (µ), Electrophilic Index (ω), Electron Donating Power (ω-), Electron Accepting Power (ω+) and Energy Gap (Eg) in order to deduce scavenging action of the two new synthesized azomethines (FD-1 and FD-2). Spin density calculations and NBO analysis were also carried out to understand the antioxidant activity mechanism. Comparison of BDE of FD-1 and FD-2 indicate the weal antioxidant potential of these structures. Conclusion: FD-1 and FD-2 have very high antioxidant potential due to the planarity and formation of intramolecular hydrogen bonds.

Fabrication and characterisation of a new methane sensor based on carbon nanotubes (CNTs) is proposed. The sensor uses low-cost SnO 2 nanoparticles and it can detect 0.5% of methane at room temperature. SnO 2 nanoparticles were deposited by electron beam deposition. The crystallography of CNT and SnO 2 was investigated by X-ray diffraction analysis. The presence of SnO 2 nanoparticles on CNTs was confirmed by scanning electron microscope images. The study's room temperature sensor is applicable in explosive environments like refineries. Furthermore, it is easily reversible (i.e. it can return to its initial state) in air at room temperature. Low power consumption and high sensitivity are also the other advantages of this sensor. Finally, a charge transfer mechanism is proposed to describe the sensing behaviour.

This brief presents the analysis and coherent design method of a high-efficiency broadband parallel-circuit Class-E power amplifier with second harmonic control circuit. The power amplifier’s (PA) broadband characteristic is achieved through analysis of the load network using double reactance compensation technique. Using a high power LDMOS transistor and operated from a 35 V supply voltage, the practical PA exhibits 41.5–44.1 dBm output power and 79%–82.2% drain efficiency over 115–155 MHz frequency range. The measurement results show good agreements with the simulation results and theory.