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Showing papers in "Arabian Journal for Science and Engineering in 2017"


Journal ArticleDOI
Harish Garg1
TL;DR: By considering all these degrees, some aggregation operators, namely picture fuzzy weighted average, picture fuzzy ordered weightedAverage, and picture fuzzy hybrid average aggregation operators have been proposed along with their desirable properties and a decision-making approach based on these operators has been presented.
Abstract: The objective of the work is to present some series of the aggregation operators for the picture fuzzy sets (PFSs). As PFSs have been an extended version of the intuitionistic fuzzy set theory which not only considers the degree of acceptance or rejection but also taken into the account the degree of refusal during the analysis. Thus, by considering all these degrees, some aggregation operators, namely picture fuzzy weighted average, picture fuzzy ordered weighted average, and picture fuzzy hybrid average aggregation operators, have been proposed along with their desirable properties. A decision-making approach based on these operators has also been presented. Finally, an illustrative example has been given for demonstrating the approach.

254 citations


Journal ArticleDOI
TL;DR: An in-depth survey and discussion of existing SDN-based DDoS attack detection and mitigation mechanisms, and they are classified with respect to the detection techniques and how this framework can be utilized to secure applications built for smart cities.
Abstract: Distributed denial-of-service (DDoS) attacks have become a weapon of choice for hackers, cyber extortionists, and cyber terrorists. These attacks can swiftly incapacitate a victim, causing huge revenue losses. Despite the large number of traditional mitigation solutions that exists today, DDoS attacks continue to grow in frequency, volume, and severity. This calls for a new network paradigm to address the requirements of today’s challenging security threats. Software-defined networking (SDN) is an emerging network paradigm which has gained significant traction by many researchers to address the requirement of today’s data centers. Inspired by the capabilities of SDN, we present a comprehensive survey of existing SDN-based DDoS attack detection and mitigation solutions. We classify solutions based on DDoS attack detection techniques and identify requirements of an effective solution. Based on our findings, we propose a novel framework for detection and mitigation of DDoS attacks in a large-scale network which comprises a smart city built on SDN infrastructure. Our proposed framework is capable of meeting application-specific DDoS attack detection and mitigation requirements. The primary contribution of this paper is twofold. First, we provide an in-depth survey and discussion of SDN-based DDoS attack detection and mitigation mechanisms, and we classify them with respect to the detection techniques. Second, leveraging the characteristics of SDN for network security, we propose and present an SDN-based proactive DDoS Defense Framework (ProDefense). We show how this framework can be utilized to secure applications built for smart cities. Moreover, the paper highlights open research challenges, future research directions, and recommendations related to SDN-based DDoS detection and mitigation.

247 citations


Journal ArticleDOI
TL;DR: A node localization scheme using the application of nature-inspired metaheuristic algorithm, i.e., butterfly optimization algorithm, is proposed and demonstrates more consistent and accurate location of nodes than the existing PSO- and FA-based node localization schemes.
Abstract: Accurate localization of sensor nodes has a strong influence on the performance of a wireless sensor network. In this paper, a node localization scheme using the application of nature-inspired metaheuristic algorithm, i.e., butterfly optimization algorithm, is proposed. In order to validate the proposed scheme, it is simulated on different sizes of sensor networks ranging from 25 to 150 nodes whose distance measurements are corrupted by gaussian noise. The performance of the proposed novel scheme is compared with performance of some well-known schemes such as particle swarm optimization (PSO) algorithm and firefly algorithm (FA). The simulation results indicate that the proposed scheme demonstrates more consistent and accurate location of nodes than the existing PSO- and FA-based node localization schemes.

133 citations


Journal ArticleDOI
TL;DR: In this article, the wave propagation of size-dependent functionally graded (FG) nanobeams resting on elastic foundation subjected to axial magnetic field based on the nonlocal strain gradient theory and Euler-Bernoulli beam model was investigated by using an analytical approach.
Abstract: This paper investigates wave propagation of size-dependent functionally graded (FG) nanobeams resting on elastic foundation subjected to axial magnetic field based on the nonlocal strain gradient theory and Euler–Bernoulli beam model by using an analytical approach. The nonlocal beam model has a length scale parameter and captures the size influences. Material properties are spatially graded according to sigmoid distribution. A derivation of the governing equations for the wave propagation analysis of nanoscale S-FGM beams is conducted. Then, the dispersion relations between wave frequency and phase velocity with the wave number is investigated. It is found that wave propagation characteristics of nonlocal S-FGM beams are influenced by various parameters including length scale parameter, material graduation, elastic foundation parameters and magnetic field intensity.

90 citations


Journal ArticleDOI
TL;DR: A feature representation with a stacked sparse auto-encoder that is based on deep learning technology is proposed that outperforms the three state-of-the-art techniques for classification of medical images.
Abstract: In the last three decades, there is considerable interest in computer-aided diagnosis systems for dealing with different diseases. Recently, these computer-aided diagnosis systems use deep learning architectures for analysis and classification of medical images. The previous techniques consider the hand-designed feature extraction approaches that depend on low-level image features, such as edges, color, and texture. Unlike these techniques, in this paper, a feature representation with a stacked sparse auto-encoder that is based on deep learning technology is proposed. The stacked sparse auto-encoder is trained in an unsupervised way. It learns the high-level features of the input pixels of unlabeled images that differentiate among different images that contain the various focal liver diseases. The proposed system consists of the preprocessing stage followed by the segmentation of the liver lesions using the level set method and Fuzzy c-means clustering algorithm. The stacked sparse auto-encoder extracts the high-level features representation from pixels of the segmented images, which are considered as the inputs for the classifier. Finally, a softmax layer classifies the different focal liver diseases by selecting the highest probabilities of each class. Using our proposed system, we have got an overall classification accuracy of 97.2%. Our proposed system is compared with three state-of-the-art techniques which are multi-support vector machine, K-Nearest Neighbor, and Naive Bayes. The experimental results show that the accuracy of classification of our proposed system outperforms the three state-of-the-art techniques.

76 citations


Journal ArticleDOI
TL;DR: In this article, the authors used the frequent measurements of mud density, Marsh funnel viscosity, and solid percent to predict the rheological properties (plastic visco-ity, apparent viscoity, yield point, flow behavior index, and consistency index of the drilling fluid) by developing empirical correlations based on 3000 field data measurements of KCl-polymer mud using artificial neural network.
Abstract: The main objective of this paper is to use the frequent measurements of mud density, Marsh funnel viscosity, and solid percent to predict the rheological properties (plastic viscosity, apparent viscosity, yield point, flow behavior index, and consistency index of the drilling fluid) by developing empirical correlations based on 3000 field data measurements of KCl–polymer mud using artificial neural network. In this paper and for the first time, the solid percent will be included in the prediction of the drilling fluid rheological parameters. The common procedure on the well site is to perform a rheological test twice a day and measure mud density, Marsh funnel viscosity, and solid percent frequently every 15–20 min. The artificial neural network (ANN) black box was converted to white box to extract the mathematical model that can predict the rheological parameters. The average absolute error for all correlations was less than 6%, and the correlation coefficient was greater than 90%. Using the developed correlations in predicting the drilling fluid properties with high accuracy will eliminate the need for tedious laboratory measurements, and real-time properties can be obtained. This technique will help the drilling engineers better monitor the drilling fluid properties and control the drilling operations by avoiding the common problems, such as pipe sticking, loss of circulation, and hole cleaning issues.

76 citations


Journal ArticleDOI
TL;DR: In this paper, a nickel-base superalloy Waspaloy was machined under minimum quantity lubrication (MQL) using a CNC milling machine with uncoated carbide inserts.
Abstract: In addition to reducing production costs, minimum quantity lubrication (MQL) aims to minimize the adverse effects of conventional cutting fluid usage on the environment and human health Because of the positive effect of the MQL system on both health and production efficiency, sustainable production is increasing daily Therefore, optimum MQL parameters must be determined in order to obtain maximum efficiency in the manufacturing process In this study, unlike similar studies in which MQL parameters were evaluated, the scope was widened and the main parameters affecting the efficiency of the system were tested at the same time For this aim, nickel-base superalloy Waspaloy was machined under MQL using a CNC milling machine with uncoated carbide inserts In the machining process, the MQL parameters selected were cutting oil type (mineral-, synthetic-, mineral-synthetic- and vegetable-based oils), fluid flow rate (25, 50, 75 and 100 ml/h), milling method (up milling and down milling), spray distance (25 and 50 mm) and nozzle type (Type 1 and Type 2) In order to analyze the effect of MQL parameters on the quality characteristics of tool life and cutting force, the cutting parameters, including cutting speed, feed rate and depth of cut, were kept constant for all experiments Taguchi’s L16 $$(4^{2}\times 2^{3})$$ orthogonal array was employed to minimize the number of experiments As a result, both maximum tool life and minimum cutting force were attained via a combination of vegetable-based cutting oil, 100 ml/h flow rate, opposite-direction (up) milling, Type 1 nozzle and a 25-mm spray distance

73 citations


Journal ArticleDOI
TL;DR: GIS-based slope movement susceptibility (SMS) map is developed for both the Ouled Driss and Machroha districts of northeastern Algeria, using the logistic regression technique as mentioned in this paper.
Abstract: GIS-based slope movement susceptibility (SMS) map is developed for both the Ouled Driss and Machroha districts of northeastern Algeria, using the logistic regression technique. Slope movement (SM) locations were spotted using the data from various sources. An inventory map containing 489 events occurred between 1987 and 2013 was used to extract the dependent variable. SM-related factors such as slope gradient, slope aspect, topographical elevations, lithology, faulting, drainage system, road network, land use, precipitations, and seismic disturbances were considered as independent variables. The effect of each parameter on SM occurrence was deduced from the corresponding coefficient that appeared in the logistic regression function. The results of this study indicated that slope gradient, lithology, and precipitations were statistically significant in predicting slope instability. The susceptibility map produced in this paper classified the study area into five categories of SMS. The high and very high susceptibility zones made up 38% of the total extent of the two commons and involved mid-altitude slopes in their central, eastern, and southern parts. The quality of the SMS map was validated, and it can be used for planning protective and mitigation measures.

57 citations


Journal ArticleDOI
TL;DR: To develop biocatalysts with sufficient activity for a commercial petroleum biodesulfurization process, it will be necessary to overcome product inhibition caused by 2-hydroxybiphenyl (2HBP) and related chemicals and to make more robust bioc atalysts.
Abstract: Desulfurization biocatalysts have been demonstrated to selectively oxidize and/or cleave carbon–sulfur bonds in a wide range of chemicals, yet an economically viable biodesulfurization process has not been developed. There are two reasons for this: failure to explore the full range of applications of biodesulfurization using existing biocatalysts and a failure to address the key factors preventing the development of biocatalysts with superior biodesulfurization activity. Existing desulfurization biocatalysts can potentially be used to detoxify chemical warfare agents or to produce surfactants, antibiotics, anticancer drugs, polythioesters, and various specialty chemicals. To develop biocatalysts with sufficient activity for a commercial petroleum biodesulfurization process, it will be necessary to overcome product inhibition caused by 2-hydroxybiphenyl (2HBP) and related chemicals and to make more robust biocatalysts. This review will discuss specifically how these limitations can be overcome.

57 citations


Journal ArticleDOI
TL;DR: In this article, the authors identified changes in pore structure and oxygen consumption characteristics of coal samples after water immersion and analyzed the composition of dissolved substance, both organic and inorganic.
Abstract: Oxidation of air-dried coal in mined-out areas is one leading factor contributing to coal spontaneous ignition during exploitation. Although some related work has been done, there is still some space for improvement. We screened out three coal samples with different ranks of coal and immersed them in distilled water for 200 days. Afterward, we identified some changes in pore structure and oxygen consumption characteristics of coal samples after water immersion. Additionally, we analyzed the composition of dissolved substance, both organic and inorganic. The results demonstrated that some parameters of three different residual coal samples increased, including average pore size, specific surface area and pore volume. In regard to the composition of dissolved substance, we identified Na+ and Cl−, which accounted for the largest proportion, along with some organic functional groups. We found that higher rank leads to a smaller total amount of dissolved substance. Additionally, we performed some experiments concerning coal oxidation rate and the amount of CO, CO2 and C2H4 generated during oxidation. The results showed that water immersion does play a significant role, along with coal rank. Considering all results and analysis, long-term water immersion is responsible for pore structure development in coal and the degree of reduction in spontaneous-ignition-proof substance, which helps to boost coal spontaneous ignition.

56 citations


Journal ArticleDOI
TL;DR: In this article, the free vibration characteristics of smart shear deformable plates made of porous magneto-electro-elastic functionally graded (MEE-FG) materials are investigated considering various boundary conditions by using an analytical method for the first time.
Abstract: In this paper, the free vibration characteristics of smart shear deformable plates made of porous magneto-electro-elastic functionally graded (MEE-FG) materials are investigated considering various boundary conditions by using an analytical method for the first time. Porosities possibly occur inside functionally graded materials (FGMs) during fabrication because of technical problems that lead to creation of micro-voids in these materials. Magneto-electro-elastic properties of FGM plate are supposed to vary through the thickness direction according to a modified power-law model in which the porosities with even and uneven distributions are approximated. The governing differential equations of porous FGM plate under magneto-electrical field are formulated through Hamilton’s principle based on a four-variable tangential-exponential refined theory which avoids the use of shear correction factors. Influences of several important parameters such as material graduation exponent, porosity volume fraction, magnetic potential, electric voltage, various boundary conditions and plate side-to-thickness ratio on natural frequencies of the porous MEE-FG plate are investigated and discussed in detail. It is concluded that these parameters play significant roles on the dynamic behavior of porous MEE-FG plates. Presented numerical results can serve as benchmarks for future analyses of MEE-FG plates with porosity phases.

Journal ArticleDOI
TL;DR: In this article, the effect of operational parameters on the ultimate tensile strength of welded joints was studied, and five levels of the tool rotation speed, welding speed, shoulder diameter, and the pin diameter in the range of 350-650-rpm, 35-95mm/min, and 12-18 and 4-6mm were investigated using a central composite design.
Abstract: Response surface methodology was employed to optimize effective factors during friction stir welding of AA7075 aluminum alloy. The effect of operational parameters on the ultimate tensile strength of welded joints was studied. Five levels of the tool rotation speed, the welding speed, the shoulder diameter, and the pin diameter in the range of 350–650 rpm, 35–95 mm/min, and 12–18 and 4–6 mm were investigated using a central composite design. In order to have rotatable and orthogonal design, 36 experiments consisting of 12 center points were conducted. Moreover, the distance of each axial point from the center point was 2. All welded joints were defect free. The statistical model showed that the welding speed and the rotation speed compared to the shoulder diameter and the pin diameter have greater impact on the response. It was found that the joint efficiency of 85% was achievable under the intermediate rotational speeds and the high welding speeds using a tool with the moderate shoulder diameters and the large pin diameters. The joint produced using the rotation speed of 513 rpm and the welding speed of 95 mm/min, the shoulder diameter of 16.1 mm and pin diameter of 5 mm yielded the highest joint strength. This joint had a joint efficiency of about 94%.

Journal ArticleDOI
Sheng-wei Fei1
TL;DR: Wang et al. as discussed by the authors presented a feature extraction method of bearing vibration signal based on wavelet packet transform-phase space reconstruction-singular value decomposition (WPS) to improve the traditional feature extraction algorithm of bearing signal.
Abstract: The excellent features of bearing vibration signal are helpful to obtain accurate diagnosis results for the failure of bearing. In this study, the feature extraction method of bearing vibration signal based on wavelet packet transform-phase space reconstruction-singular value decomposition (WPS) is presented to improve the traditional feature extraction method of bearing vibration signal based on wavelet packet transform-singular value decomposition (WS). In the proposed feature extraction method, singular value decomposition is performed for phase space reconstruction signal of each wavelet packet coefficient’s reconstructed signal of bearing vibration signal. The dynamic characteristics of a certain frequency range can be reflected by phase space reconstruction for wavelet packet coefficients’ reconstructed signals of bearing vibration signal. Support vector machine (SVM) is a machine learning method based on structural risk minimization principle, and SVM classifier can solve the classification problems with small training samples, high dimensions, and nonlinearity. Thus, the SVM model of bearing is established by the features of bearing vibration signal based on wavelet packet transform-phase space reconstruction-singular value decomposition in this study. The experimental results show that the feature extraction method of bearing vibration signal based on wavelet packet transform-phase space reconstruction-singular value decomposition is better than the feature extraction method of bearing vibration signal based on wavelet packet transform-singular value decomposition, and SVM established by the features of bearing vibration signal based on wavelet packet transform-phase space reconstruction-singular value decomposition (WPS-SVM) has a stronger fault diagnosis ability of bearing than SVM established by the features of bearing vibration signal based on wavelet packet transform-singular value decomposition (WS-SVM).

Journal ArticleDOI
TL;DR: In this paper, a geographical information system-based model that combines fuzzy logic and analytic hierarchy process (AHP) is proposed to delineate suitable areas for constructing water harvesting (WH) structures in arid southern Iraq.
Abstract: Identifying potential sites for water harvesting (WH) is a crucial task for efficient water resources management in arid regions. In response, this paper proposes a geographical information system-based model that combines fuzzy logic and analytic hierarchy process (AHP) to delineate suitable areas for constructing WH structures in arid southern Iraq. Based on a literature review and available data, five influential factors were selected to develop the model: hydrological soil group, land cover, surface runoff depth, slope, and distance to an intermittent river. A fuzzy logic-based approach was used to standardize the factors, and AHP was used to derive weights. The total score for land suitability was obtained from a linear aggregation of the products of fuzzy standard criteria and AHP-derived weights. The WH suitability levels obtained were classified into five different classes: unsuitable, poor, moderate, good, and excellent. The study revealed that 393 $$\hbox {km}^{2}$$ (18% of the area) is unsuitable or poor, 538 $$\hbox {km}^{2}$$ (26%) is moderately suitable, and 1167 $$\hbox {km}^{2}$$ (56%) is good or excellent for WH in the study area. Field data revealed that the only existing WH dam in the area is situated within an excellent WH-suitable zone, which indicates the capability of the developed model to identify areas suitable for different WH structures.

Journal ArticleDOI
TL;DR: In this article, a modified mean value (MMV) method is proposed to improve the efficiency and robustness of inverse reliability method to evaluate the reliable level in RBDO-based PMA.
Abstract: The advanced mean value (AMV) is generally implemented to evaluate the probabilistic constraints of reliability-based design optimization (RBDO) problems based on performance measure approach (PMA). The PMA-based AMV is efficient method but yields unstable results for highly nonlinear probabilistic constraints. In this paper, a modified mean value (MMV) method is proposed to improve the efficiency and robustness of inverse reliability method to evaluate the reliable level in RBDO-based PMA. The modified PMA using MMV is adaptively evaluated using a modified search direction based on the two previous performance values. The modified search direction is determined using an adaptive step size, which is simply computed based on a power function and adaptive factor between 0.95 and 1. The robustness and efficiency of proposed MMV are compared with several reliability methods-based PMA including the AMV, hybrid mean value (HMV), enriched HMV (HMV $$^{+}$$ ) and modified chaos control (MCC) through four mathematical and structural RBDO problems with nonlinear probabilistic constraints. The results illustrated that the proposed MMV is as robust as the MCC and HMV $$^{+}$$ but is computationally more efficient. In addition, the MMV is more robust than the HMV and AMV for RBDO problems with highly probabilistic constraints.

Journal ArticleDOI
TL;DR: In this paper, the physicochemical and engineering properties of textile effluent treatment plant (ETP) sludge have been studied in the laboratory to characterize and find a potential use of textile ETP sludge produced in Bangladesh.
Abstract: The main objective of this study is to characterize and find a potential use of textile effluent treatment plant (ETP) sludge produced in Bangladesh. Textile ETP sludge collected from the local textile industries have been characterized in the laboratory. The physicochemical and engineering properties of the sludge have been studied. Collected ETP sludge has been processed to get cement-like fine powder that has been used for partial replacement of Portland cement/sand in the composition of the mortar and concrete specimens. Different mechanical (compressive and flexural strength), physical (water absorption) and morphological (porosity) properties of the test specimens have been evaluated. The test result shows that the addition of sludge in the mortar and concrete composition as a substitution of Portland cement or sand decreases the compressive strength and flexural strength, and increases the water absorption and porosity of the mortar and concrete specimens. Leaching study, conducted for the sludge-based mortar and concrete specimens following tank leaching test procedure, reveals that the concentration of leached metals is quite low than the limits specified by the Department of Environment in Bangladesh. These results amply demonstrate that textile ETP sludge can be utilized for making non-structural building components where lower strength is justified.

Journal ArticleDOI
TL;DR: In this article, different methods of flushing are used to study the machining characteristics of electric discharge machining (EDM) using AISI 5160 alloy steel to investigate the performance of EDM.
Abstract: In this paper, different methods of flushing are used to study the machining characteristics of electric discharge machining (EDM). Flushing mode plays an important role in any EDM operation. An incorrect flushing can result in erratic cutting and poor machining conditions. In present work, AISI 5160 alloy steel is selected as a work material to investigate the performance of EDM. Two of the most important response variables, surface roughness (SR) and material removal rate (MRR), are selected to compute the influence of input control factors. Central composite design is used for experimentation planning using response surface methodology. Analysis of variance is utilized to investigate the influence of control factors on response. Mathematical models are solved with the help of non-dominating sorting genetic algorithm II (NSGA-II). Validation experiments confirmed that at the optimal levels of process parameters the predicted values of MRR and SR were 1.167 g/min and $$1.280\,\upmu \hbox {m}$$ , respectively. The predicted values of MRR and SR suggested by NSGA-II give a better correlation with experimental values, i.e., 1.149 g/min and $$1.327\,\upmu \hbox {m}$$ , respectively.

Journal ArticleDOI
TL;DR: In this article, a fuzzy TOPSIS hybrid approach is used for selection of an optimal parametric combination for laser beam micro-marking process parameters, such as current, pulse frequency, and scanning speed.
Abstract: The process parameter selection in any machining process is one of the most challenging criteria for effective machining. Selection of an optimal parametric combination always results in efficient machining. In the current work, a fuzzy TOPSIS method for selection of optimal laser beam micro-marking process parameters, such as current, pulse frequency, and scanning speed, during laser beam marking on gallium nitride is adopted. Response surface methodology (central composite design) is adopted for the experimental design. The mark width, mark depth, and mark intensity are considered as the process responses. The mark width and mark depth are measured with the help of a precision optical microscope. Microscopic images are then treated using image processing software to calculate the mark intensity. A multi-criteria decision-making model is developed considering the effect of process parameters on process response for selection of optimal process parameter in the laser beam micro-marking process. The triangular fuzzy number is used to calculate the weight of each performance criteria, and the fuzzy TOPSIS hybrid approach is used for selection of optimal parametric combination. The results indicate that a small pulse frequency and high current and scanning speed lead to increase in mark intensity.

Journal ArticleDOI
TL;DR: In this article, the authors summarize the recent developments in the evaluation of the tribological characteristics such as friction and wear of surface modified metallic biomaterials, such as poly(ethylene glycol)-like (tetraglyme), diamond-like carbon, Ti-C:H, tantalum, CNT-reinforced hydroxyapatite, ultrahigh molecular weight polyethylene, and titanium nitride and micronite coatings.
Abstract: Biomaterials are extensively used in the medical field for biological tissue replacement and internal support, such as joint replacement, dental roots, and orthopedic implants. The release of ions and lack of wear resistance of biomaterials result in implant loosening which leads to implant failure. Therefore, surface modification of such biomaterials is essential to ensure a prolonged implant life. The purpose of this review is to summarize the recent developments in the evaluation of the tribological characteristics such as friction and wear of surface-modified metallic biomaterials. Surface modification reviewed include coatings such as poly(ethylene glycol)-like (tetraglyme), diamond-like carbon, Ti–C:H, tantalum, CNT-reinforced hydroxyapatite, ultrahigh molecular weight polyethylene, and titanium nitride and micronite coatings and surface treatments such as ion implantation, Plasma-immersed ion implantation, carburization, and thermal oxidation have been discussed.

Journal ArticleDOI
TL;DR: In this article, a super-twisting algorithm-based sliding-mode observer for uncertain nonlinear fractional-order system subject to unknown inputs is proposed, and the convergence and robustness are proven.
Abstract: This paper deals with the design of super-twisting algorithm-based sliding-mode observer for uncertain nonlinear fractional-order system subject to unknown inputs. Fractional-order super-twisting algorithms (FSTA) are proposed for both commensurate and incommensurate fractional-order nonlinear systems. Then, step-by-step sliding-mode observers based on the FSTA are designed. Finite-time convergence and robustness are proven. Finally, application to the synchronization of two fractional-order chaotic systems is given.

Journal ArticleDOI
TL;DR: In this article, two series mixtures of choline chloride, urea, and glycerol, at room temperature, were synthesized in different molar ratios and their properties were studied.
Abstract: Deep eutectic solvents are a recent class of solvents that started to get attention to replace the ionic liquids and, of course, the traditional organic solvents. In this work, two series mixtures of choline chloride–urea–glycerol and choline chloride–malic acid–glycerol, liquids at room temperature, were synthesized in different molar ratios and their properties were studied. Electrochemical characterization test was performed using Pt/C catalyst and the results showed an interesting electrochemical stability for choline chloride–urea–glycerol mixture within the potential range of −1 to 1 V. The viscosity was reported as a function of temperature for mixtures which behaved as Newtonian fluids and as a function of shear rate for those which behaved as non-Newtonian fluids. For instance, 1–1–1 choline chloride–urea–glycerol viscosity was decreased from 706.8 to 26.9 cP when the temperature was increased from 20 to 80 $${^{\circ }}$$ C, respectively. While for the same mixture at 10 $${^{\circ }}$$ C, it was decreased from 30,933 to 3948 cP by increasing the shear rate from 0.03 to 0.38 S $$^{{-}1}$$ , respectively. Thermogravimetric analysis, differential scanning calorimeter and density measurements were all reported in detail in this paper.

Journal ArticleDOI
TL;DR: In this paper, a review of NDT techniques for condition evaluation of old structures and historic monuments based on available literature has been presented, and the authors have also discussed a number of national and international standards (codes) established by technical societies as standard guidelines for applying NDT methods.
Abstract: The paper discusses non-destructive tests (NDTs) useful for condition evaluation of old structures and historic monuments based on a review of available literature. The application of these tests for the evaluation of various structures constructed of stone or brick masonry or reinforced cement concrete has been discussed. The types of defects present in structures built of different material media vary greatly. Therefore, it has been recognized that not all NDT methods or all combinations of NDT methods can be used for all structures. Further, the type and degree of a structural defect is a function of the environment the structure is subjected to. Because of the great amount of research which has been recently conducted in this field, general parameters which could be identified by various NDT techniques for various building materials and the advantages and disadvantages of each technique need to be identified. The authors have been able to achieve this by means of a literature survey. The authors have also discussed a number of national and international standards (codes) established by technical societies as standard guidelines for application of NDT techniques. A few abnormalities in this regard have also been discussed.

Journal ArticleDOI
TL;DR: In this paper, support vector machine regression (SVR) technique was used for predicting the uniaxial compressive strength of FRP confined concrete and the prediction efficacy of developed SVR models was compared with that of ANN and existing empirical FRP strength prediction models.
Abstract: Support vector machine regression (SVR) technique was used for predicting the uniaxial compressive strength of FRP confined concrete Two different SVR models, viz SVR model for carbon fiber reinforced polymer confined concrete and SVR model for glass fiber reinforced polymer confined concrete, were developed The prediction efficacy of developed SVR models was compared with that of ANN and existing empirical FRP strength prediction models Furthermore, for assessing variable contributions in strength prediction process, a sensitivity analysis is also presented The study showed that SVR could be a powerful alternative physical tool for strength prediction of FRP confined concrete

Journal ArticleDOI
TL;DR: This paper presents a safe and reliable three-factor authentication scheme usable in multi-server environment and gives strong security as well as better complexity in the terms of communication cost, computation cost and estimated time.
Abstract: Recently, Wen et al have developed three-factor authentication protocol for multi-server environment, claiming it to be resistant to several kinds of attacks In this paper, we review Wen et al’s protocol and find that it does not fortify against many security vulnerabilities: (1) inaccurate password change phase, (2) failure to achieve forward secrecy, (3) improper authentication, (4) known session-specific temporary information vulnerability and (5) lack of smart card revocation and biometric update phase To get rid of these security weaknesses, we present a safe and reliable three-factor authentication scheme usable in multi-server environment The Burrows–Abadi–Needham logic shows that our scheme is accurate, and the formal and informal security verifications show that it can defend against various spiteful threats Further, we simulate our scheme using the broadly known Automated Validation of Internet Security Protocols and Applications tool, which ensures that it is safe from the active and passive attacks and also prevent the replay and man-in-the-middle attacks The performance evaluation shows that the presented protocol gives strong security as well as better complexity in the terms of communication cost, computation cost and estimated time

Journal ArticleDOI
TL;DR: In this article, the effect of cerium substitution in nanocrystalline magnesium ferrite was studied and the cation distribution was proposed based on the intrinsic vibrations of tetrahedral group and octahedral groups.
Abstract: Effect of cerium substitution in Nanocrystalline magnesium ferrite, $$\hbox {MgCe}_x\hbox {Fe}_{2-x}\hbox {O}_{4}$$ ( $$x = 0.00, 0.02, 0.04$$ and 0.06) synthesized by sol–gel auto-combustion process has been studied. X-ray diffraction reveals the single-phase cubic spinel structure, X-ray density and porosity increase with concentration of ceria. Scanning electron microscopy micrograph shows agglomeration of ceria. Fourier transform infrared spectroscopy confirms the formation of spinel phase with two frequency bands, $${ u }_{1}$$ at around $$590\,\hbox {cm}^{-1}$$ and a lower frequency band $${\upnu }_{2}$$ at $$430\,\hbox {cm}^{-1}$$ , which were attributed to intrinsic vibrations of tetrahedral group (A-site) and octahedral groups (B-sites), respectively, based on this the cation distribution is proposed as $$(\hbox {Mg}_{y-x}^{2+}\,\hbox {Fe}_{ 1-y+x}^{3+})_{\mathrm{A}}[\hbox {Mg}_{1-y}^{2+}\,\hbox {Fe}_{ 1+y-x}^{3+} \hbox {Ce}_{x}^{3+}]_\mathrm{B}\,\hbox {O}_{4}^{2-}$$ . The force constant for tetrahedral sites was less than that of octahedral sites. X-ray photoelectron spectroscopy spectra reveals the oxidation state of Fe by two peaks in the region of 712 and 724 eV corresponding to $$2p_{3/2}$$ and $$2p_{1/2}$$ , respectively, with $$\Delta E = 12$$ eV. The chemical state of Ce was confirmed by peaks at BE 884 and 902 eV corresponding to $$3d_{5/2}$$ and $$3d_{3/2}$$ , respectively. vibrating sample magnetometer studies show that the magnetization strongly depends on $$\hbox {Ce}^{3+}$$ substitutions. Saturation magnetization has decreased up to $$x=0.04$$ and then increased which can ascribed to decrease in canting angle. All the samples were in superparamagnetic state.

Journal ArticleDOI
TL;DR: The complete nonlinear dynamic model is obtained by exploiting Newton–Euler method as a common technique used in quadcopter modelling and it is shown that the designed controller is robust against sensor noise, external disturbances, and model parameters uncertainties.
Abstract: This work presents a detailed mathematical modelling of H-shaped racing quadcopter. The complete nonlinear dynamic model is obtained by exploiting Newton–Euler method as a common technique used in quadcopter modelling. A trajectory tracking controller is proposed, in which four PID controllers are designed to stabilize the quadcopter and to achieve the required altitude and orientation. However, a nested loop PID controllers are designed to track the desired x and y position of the quadcopter. The PID coefficients for the aforementioned proposed controllers are tuned using genetic algorithm (GA). The objective function for the GA was set so as to minimize the absolute tracking error, peak overshoot, and settling time for a step inputs. A MATLAB/Simulink environment is used to conduct the system model and the designed controller. The closed loop system performance is depicted for individual step inputs and for a predefined trajectory. Simulation results show a perfect step response performance and excellent trajectory tracking capability with a very low error budget. Finally, the controller robustness is examined and it is shown that the designed controller is robust against sensor noise, external disturbances, and model parameters uncertainties.

Journal ArticleDOI
TL;DR: In this article, a novel magnetic chitosan hydrogel film, crosslinked with glyoxal (Fe3O4NPs/CS/glyoxal), has been synthesized and used as an easily reusable adsorbent for 80-90 % removal of toxic Cr(VI) from water.
Abstract: A novel magnetic chitosan hydrogel film, cross-linked with glyoxal (Fe3O4NPs/CS/glyoxal), has been synthesized and used as an easily reusable adsorbent for 80–90 % removal of toxic Cr(VI) from water. A pseudo-second-order kinetic (with correlation coefficient R2 > 0.99) is observed at room temperature. Characterization of the absorbent is carried out by X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. The adsorption isotherm is well fitted in the Langmuir equation at different temperatures [R2 > 0.99, and 0 < (Langmuir separation factor, RL) < 1]. So, our adsorbent, with the novelty of using glyoxal, and the ease of separation may be considered in Cr(VI) wastewater treatment technology.

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TL;DR: In this article, a simple and cost-effective manufacturing process was employed to prepare composite honeycomb sandwich panels for aerospace applications, and different curing temperatures and curing times were employed to optimize the curing parameters of the adhesive film to join CF-epoxy facesheets with the honeycomb core.
Abstract: A simple and cost-effective manufacturing process was employed to prepare composite honeycomb sandwich panels for aerospace applications. Carbon fiber–epoxy matrix composite facesheets were first prepared by vacuum-assisted resin transfer molding, and later these facesheets were bonded with the Nomex\(^{\textregistered }\) honeycomb core by compression technique wherein the whole sandwich assembly containing facesheets, epoxy- based adhesive film and honeycomb core was clamped between two parallel metallic plates followed by curing in oven. Different curing temperatures, i.e., 100, 110, 120 and 130\({^{\circ }}\)C, and curing times, i.e., 2 and 3 h, were employed to optimize the curing parameters of the adhesive film to join CF–epoxy facesheets with the honeycomb core. The optimization of the curing parameters was related to the maximum load-bearing capability of composite honeycomb sandwich panels under three-point bend test and associated mechanical properties. It was shown that the composite honeycomb sandwich panels cured at 130\({^{\circ }}\)C for 3 h demonstrated maximum mechanical performance.

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TL;DR: In this paper, the authors modify the existing process capability index (PCI) for a Weibull distribution and construct bootstrap confidence intervals (BCIs) for the newly proposed index.
Abstract: The objective of the paper is to modify the existing process capability index (PCI) for a Weibull distribution and to construct bootstrap confidence intervals (BCIs) for the newly proposed index. Three BCIs that consist of standard, percentile and bias-corrected percentile bootstrap (BCPB) confidence intervals are constructed for the newly proposed index and the existing Pearn and Chen index. The efficiency of the newly proposed index \(C_{\mathrm{GPK}} \) is compared with Pearn and Chen index using their coverage probabilities and average widths. The coverage probabilities and average width of three BCIs were calculated using Monte Carlo simulation studies. The newly proposed index shows better performance than Pearn and Chen index. The results indicate that BCPB confidence interval was more efficient in both cases and outperform other two confidence intervals in all situations. The comparison of average width of BCPB apparently shows that the proposed index performed better in all cases. A real-life example is also provided for a practical application.

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TL;DR: In this paper, the phase change sequence and effects of salt on frozen soils were discussed, based on the theory of solution phase diagram and phase change in porous media, the differences and similarities of phase change between pore solution and free solution were analyzed.
Abstract: Detrimental frost heave and salt expansion may occur in saline soils of cold regions. The severity of these processes depends on the amount of salt precipitation and ice crystal growth in the pore solution at different temperatures. By employing nuclear magnetic resonance, the liquid water fractions in different concentrations of sodium chloride and sodium sulfate saline soils were measured at different temperatures. Based on the theory of solution phase diagram and phase change in porous media, the differences and similarities of phase change between pore solution and free solution were analyzed. The phase change sequence and effects of salt on frozen soils are also discussed. The theoretical and experimental results confirm that the phase diagram can reflect the phase change of pore solutions roughly, and pore size distribution is the cause of differences between the pore solution and free solution. Sodium chloride can mitigate the frost heave of soil, and frost heave and salt expansion occur together when the sodium sulfate soil is frozen.