International Journal of Engineering
Volume:34 Issue: 6, Jun 2021

In this paper, the flexural performance of Fibre Reinforced Concrete (FRC) with an optimised spirally deformed steel fibre developed by the authors is evaluated experimentally. For comparison purposes, concrete specimens with commercially available steel fibres (hooked-end and crimped) are tested and included in the study. The experiment parameters include two different matrices with 28-day compressive strengths of 35 MPa and 45 MPa and four fibre volume contents (0.2%, 0.35%, 0.5%, and 0.65%). Besides, specimens with plain concrete are also tested as reference. Findings of the research indicate that the spirally deformed steel fibre considerably enhances flexural characteristics of concrete compared with existing fibres on the market (hooked-end and crimped) where the deflection-hardening response (even at the presence of wide cracks) can also be achieved even with low fibre dosages common in practice. Therefore, such a composite, i.e. concrete reinforced with spirally deformed steel fibre, can be deemed as a structural material.

Roof tiles are the most common roof coverings in Indian buildings, especially in traditional residential buildings. Given the important role of roofing characteristics in building energy efficiency and indoor thermal comfort conditions, innovative solutions to improve the thermal energy performance of this diffused roofing element have become a key research issue. In this perspective, cool roofing applications represent an effective solution to this objective. The present work deals with the analysis of innovative cooling roof tile manufactured using a combination of Metakaolin with different percentages, EPS, sodium silicate and coating material. The experimental work was carried out during day and night. The thermal performance of cool roof tiles were assessed in terms of the open-air temperature compared to the thermal performance of ordinary roofing tile. The report discovered that using revolutionary cool roofs greatly increased thermal comfort during the daytime, and preserved thermal comfort during the night. The innovative cool roof tile is cheaper, easier to implement, and less expensive compared to other roofing technologies. The study revealed that the roof's exterior and interior surface temperature reduced about 8°C and 12°C, respectively during day time, while roof's exterior and interior surface temperature maintain atmospheric temperature during night time. The compressive and transverse breaking strength was increasing about 9.1% and 39.6%.

Nowadays, hyperspectral images (HIs) are widely used for land cover land use (LCLU) mapping. Hyperspectral sensors collect spectral data in numerous adjacent spectral bands, which are usually redundant. Hyperspectral data processing comes with important challenges such as huge processing time, difficulties in transfer, and storage. In this study, two supervised and unsupervised dimensionality reduction methods are proposed for hyperspectral feature extraction based on the band clustering technique. In the first method, the unsupervised method, after the unsupervised band clustering stage with some statistical attributes, the principal component transform is used in each cluster, and the first PC component is considered an extracted feature. In the second method, the supervised method, bands are clustered based on training samples mean vectors of each class, and the weighted mean operator is used for feature extraction in each cluster. The experiment is conducted on the classification of real famous HI named Indian Pines. Comparing the obtained results and some other state of art methods proved the proposed method's efficiency.

Language identification is a critical step prior to any natural language processing. In this paper, a signal processing method for Language Identification is proposed. Sequence of characters in a word and the order of words in stream identify the language. The sequence of characters in a stream provides a signature to recognize the language without understanding its meaning. The signature can be extracted using signal processing techniques via converting texts into time series. Although several research and commercial software have been developed to identify text language, they need a standard dictionary for each language. We proposed a dictionary independent method consisting of three main steps, I) preprocessing, II) clustering and finally III) classification. First, the texts are converted to time series using UTF-8 codes. Second, to group similar languages, the obtained series are clustered. Third, each cluster is decomposed into 32 sub-bands using a Wavelet packet, and 32 features are extracted from each sub-band. Also, a multilayer perceptron neural network is used to classify the extracted features. The proposed method was tested on our dataset with 31000 texts from 31 different languages. The proposed method achieved 72.20% accuracy for language identification.

Nowadays, maximizing profits, decreasing operating cost and scheduling tasks are the most important issues of cloud computing with its growing usage. In this regard, one of the challenges in cloud computing is to provide an efficient method to deploy virtual machines on physical machines with the aim of optimizing energy consumption, fair load distribution and task scheduling. The purpose of present study is to provide a method for improving task scheduling through an improved particle swarm optimization algorithm. In the proposed method of present study, selection of a proper objective function has led to balanced workload of virtual machines, decreased time of all tasks as well as maximum utilization of all resources and increased productivity in addition to dynamic placement of virtual machine on physical machine. The results of simulation showed that the proposed method has provided an optimized solution for scheduling tasks, equal allocation of tasks in virtual machines and placement on the appropriate physical machine and less time with an improvement of 0.02 has been spent on the process of outsourcing virtual machines.

One of the critical components for the efficient operation of single-phase grid-connected converters is the synchronization unit. This paper presents a fast and adaptive phase-locked loop (PLL) structure that ameliorates the dynamic response of the estimated frequency and amplitude for grid-connected single-phase power systems. The second-order generalized integrator (SOGI) with a novel frequency-locked loop (FLL) is utilized which contains a DC offset rejection loop. The proposed method not only eliminates the transient response of the estimated frequency which is produced by FLL in grid voltage phase angle jumps, but also improves the PLL dynamic characteristics. The whole system has been simulated in MATLAB Simulink environment where a very small settling time for the estimated frequency of the FLL has been achieved. Therefore, it will improve the whole dynamic parameters of the system. Based on the simulation results, the settling time for the estimated frequency and amplitude are 22 ms and 10 ms, respectively.

A multiphase sinusoidal oscillator (MSO) using dual output voltage differencing buffered amplifier (DO-VDBA) is presented in this paper which provides n equally spaced phase sinusoids of equal magnitudes. The proposed MSO topology is realized using the first order all pass network (APN). In the proposed structure the output voltages are made available at low impedance nodes which makes the proposed MSO easy for cascadability. Making the proposed structure a resistorless structure is a major challenge. The main benefits of the structure are easy integration and less power losses. The formulation of frequency and condition of oscillation is derived mathematically. The oscillation frequency can be tuned electronically, is an added advantage of the proposed MSO. The effect of device non-idealities is also discussed in the study. To assess the proposed MSO performance further Monte Carlo analysis was carried out. The workability of the proposed structure is verified through SPICE simulations for a three (n=3) and four (n=4) phases MSO, and the obtained simulated results are in close agreement with the theoretical values. The total harmonic distortion (THD) is found to be quite low.

In video surveillance, multiple objects tracking (MOT) is a challenging task due to object matching problem in consecutive frames. The present paper aims to propose an improved object matching approach in MOT based on Zernike Moments and combination of multiple similarity distance metrics. In this work, the object is primarily detected using background subtraction method while the Gaussian Mixture Model (GMM) is applied for object extraction in the next frames. Subsequently, the color histogram and the magnitude of Zernike moments of the objects are calculated. In the next step, the objects are matched in the current and the previous frames based on the Hausdorff distance between objects, Earth Mover's (EMD) distance between their color histograms, and Chi-square distance between their Zernike moments. Then, a voting mechanism is designed to find the best consensus object matching from the aforementioned metrics. Eventually, the location of each object is predicted by the Kalman filter to continue tracking in subsequent frames. The results show that the object tracking and matching performance is improved using the proposed method in the video sequences of the multi-camera pedestrian "EPFL" video dataset. Specifically, errors caused by the merging of targets are reduced in the proposed tracking process.

A large number of single-phase loads and sources create unbalanced voltage in microgrids. Voltage unbalance reduces the power quality, which results in misoperation or failure of customer equipment and microgrid. Also, voltage unbalance negatively impacts induction motors, power electronic converters, and adjustable speed drives.  Static synchronous compensator (STATCOM), as an influential segment of the Flexible Alternative Current Transmission Systems (FACTS), has been extensively utilized as shunt compensators for controlling reactive power and regulation voltage in transmission and distribution networks. Under unbalanced conditions, an oscillating couple between the positive and negative sequence components of control loops emerge in the d-q frame. This paper suggests an innovative point of common coupling (PCC) voltage controller in Decoupled Double Synchronous Reference Frame (DDSRF) to compensate for an unbalanced PCC voltage and reduce the oscillating couple using STATCOM. Implementation of the proposed DDSRF involves several steps. Firstly, unbalance signals are rotated counterclockwise to split up the positive sequences. Secondly, those signals are rotated clockwise to separate negative sequences. Finally, by utilizing mathematical equations, the proposed DDSRF is introduced, which enables independent control of positive and negative sequence components. This study controls DC capacitor voltage for unbalanced conditions. Furthermore, the regulation voltage at PCC is performed. The control system scheme is also designed under unbalanced conditions, and simulation results guarantee the suggested control strategy.

One of most emerging technology in the recent years in the field of wireless communication is the Cognitive Radio (CR) technology, which reduces spectrum scarcity significantly. The main function of CR technology is detecting spectrum holes or unused spectrum of primary users (PUs), also called as licensed users, and assigning this unused spectrum to the secondary users (SUs), also called unlicensed users. As the CR technology is open to every user, there are many security issues such as Primary User Emulsion Attack (PUEA), Jamming Attack, Spectrum Sensing Data Falsification (SSDF) Attack, Lion Attack, and Sink Hole Attack and so on. SSDF attack is the one of major security attack in cognitive radio in which a malicious user sends false data intentionally to the other secondary users. The main aim of the SSDF attack is to disturb the communication between the secondary users or to gain more channel resources. One of the solutions to mitigating SSDF attack is the cooperative spectrum sensing. In this paper, we propose a new algorithm of cooperative sensing based on trust values of secondary users, and compares with the conventional cooperative spectrum sensing with the proposed algorithm. The simulation of cooperative sensing also performed in both time variant channel and time invariant (Rayleigh) channel. The authors also compare the three basic hard fusion techniques such as AND, OR, MAJORITY rule

Channel estimation is a crucial task for orthogonal frequency division multiplexing (OFDM) modulation-based systems since this estimation is used for compensating impacts of a wireless channel. Recently, sparse representation (SR) is proposed for this task as wireless channels are considered as a sparse signal. However, SR considers sparse as the main feature and omit other features of the channel while estimating the channel. In this paper, we propose a general framework for utilizing other features of the channel in sparse channel estimation for OFDM systems, while these features are omitted in conventional sparse methods. In this regard, by utilizing maximum a posterior (MAP) estimation and defining new parameters, these features are conveyed into sparse channel estimation process to improve channel estimation. The simulation results indicate that our proposed framework not only improves the estimated parameter, but also reduces the number of resources such as the number of estimation pilots or transmitted power.

For transformer designers, split-winding transformer modeling in different frequency ranges is of great importance. In this paper, for the first time, a multi-conductor transmission line model is proposed for high-frequency modeling of the split-winding transformer. In this model, all the turns in layers and disks have been considered and the model's parameters have been calculated using the finite element method. In order to validate the proposed model, the results are compared with the result of a model, which is based on finite element and coupled field-circuit. It is shown that the introduced model has good accuracy and it can be employed for split-winding transformer modeling in different frequency ranges. In addition, using the validated multi-conductor transmission line model, the frequency response of the split-winding transformer and disk-to-disk short circuit fault are analyzed.

The main challenge in blood supply chain is the shortage and wastage of blood products. Due to the perishable characteristics of this product, saving a large number of blood units on inventory causes the spoil of these limited and infrequent resources. On the other hand, a lack of blood may lead to the cancellation of health-related critical activities, and the result is a potential increase in mortality in hospitals. In this paper, an integer programming model was proposed to minimize the total cost, shortage, and wastage of blood products in Namazi hospital by considering the different types of blood groups. The parameters in the real-world are uncertain, and this problem will be examined in the paper. The robust fuzzy possibilistic programming approach is presented, and a numerical illustration of the Namazi hospital is used to show the application of the proposed optimization model. Sensitivity analysis is conducted to validate the model for problems such as certainty level, coefficient weight, and penalty value of the objective function in the robust fuzzy possibilistic programming. The numerical results imply the model is able to control uncertainty and the robustness price is imposed on the system; therefore, the value of the objective function in the robust fuzzy possibilistic is 80% lower than probabilistic.

Reduced graphene oxide (rGO) and M-type hexagonal ferrites such as BaFe12O19 have attracted great attention as electromagnetic (EM) wave absorbing materials in recent years. In this research, different weight percents of BaFe12O19/rGO nanocomposites were incorporated into the microwave absorbing layers and their EM wave absorption was investigated. Barium ferrite was synthesized through the co-precipitation method. Graphene oxide (GO) was synthesized through the modified Hummers’ method. The synthesized GO was reduced to rGO nanosheets using a reducing agent. The synthesized barium ferrite and rGO were then mechanically milled to form BaFe12O19/rGO nanocomposite. The chemical bondings, phase analysis, magnetic properties, particle morphology, and EM wave absorbing properties were investigated using FTIR, XRD, Vibration Sample Magnetometer (VSM), FESEM, and Vector Network Analyzer (VNA), respectively. The saturation magnetization (Ms) and the coercivity (Hc) of the synthesized BaFe12O19/rGO nanocomposite were 31 emu/g and 1.5 kOe, respectively. The EM absorption properties in the X-band (8.2-12.4 GHz) showed that the maximum reflection loss (RL) of -7.39 dB could be obtained for the nanocomposite containing only 10 wt. % of BaFe12O19/rGO nanocomposite in a resin matrix with a thickness of 2 mm.

The purpose of this study is to define a piecewise fatigue damage model (PFDM) for the prediction of damage in composite laminates under cyclic loading based on the continuum damage mechanics (CDM) model. Assuming that damage in fiber-reinforced plastic structures accumulates nonlinearly, a piecewise degradation growth function is defined and coupled with CDM and micromechanics approaches. The model divides the damage behavior of fiber, matrix, and fiber/matrix debonding at the ply scale, into three different stages. For generality, a fully multi-stage damage formulation on a single-ply level is employed. The unknown parameters of the PFDM are estimated according to obtained experimental data of damage mechanisms associated with the composites laminate under cyclic loading. To predict multidirectional composite laminates' fatigue life, the proposed model was implemented in Abaqus software by the subroutine. In a validation against experimental data on carbon fiber reinforced material, the model proves to provide a good numerical approximation of the damage during the fatigue loading. The results reveal that by considering the multi-stage process in stiffness reduction, the proposed model can estimate the fatigue life of composite laminate under multiaxial cyclic loading conditions more accurately than the similar model in the literature.

In advance composite material the propagation of crack is a regular failure problem in various engineering applications especially in aircrafts body. The aircraft body components are subjected to various thermal and mechanical loading conditions. It is very difficult, time-consuming and costly process of testing the aircrafts components failure due to various thermal and mechanical conditions. Strain energy release rate (SERR) is the significant parameter for the composite materials and quality of composite materials depends in SERR values.The present investigation is based on ANSYS analysis for finding the strain energy release rate (SERR) value using Virtual Crack Closure Technique (VCCT) to understand the fracture behavior of the composite lamina. The circular crack present in the middle of the composite plate and subjected to Pressure and temperature loading for different angle (cross-ply& and angle-ply) composite structure laminas. The angle-ply shows less SERR in mode I & II while cross-ply shows less SERR in mode III under the constant Pressure loading conditions. Mode II shows the maximum SERR in cross-ply compared to mode I and III for temperatures 30ºC,80ºC, 130 ºC & 180ºC. SERR for mixed-mode was found by considering the total mode of fracture and validation based on published literature for SERR due to the Thermal load of mode I (GI) for different fiber layup configurations of the circular cut-out.

The present study aimed to introduce a numerical method to study ratcheting strains of rectangular plates. A new numerical analysis was conducted by development of dynamic relaxation method combined with MATLAB software to evaluate the ratcheting behavior of the thin steel plate under mentioned loading condition. In order to verify the results, experimental tests were performed under stress-controlled conditions by a zwick/roell amsler HB100 machine and bending ratcheting of CK45 steel plate at room temperature was studied. Under stress-controlled conditions with non-zero mean stress, ratcheting behavior occurred on thin plate. Moreover, a finite element analysis was carried out by Abaqus using nonlinear isotropic/kinematic (combined) hardening model. The results showed that the rate of ratcheting strain decreased with an increase in cycle number. It was found that the hysteresis loops were wider in experimental method than those of other methods because of more energy dissipation. The numerical results are in a good agreement with the simulation and experimental data. Comparison of errors between these methods obviously demonstrate high accuracy of the new introduced method.

Natural gas must be preheated to prevent phase change and gas hydrate in pressure reduction stations. This paper aims to investigate the effect of the fins of gas tubes and their configuration, arrangement, and shape on the heat transfer and thermal efficiency of gas. To conduct a parametric study, two tube cases with fins and without fins, and in the finned case for the fin’s configuration, two longitudinal and circular arrangements, and the formation of the fins, two solid and interrupted forms were analyzed. Also, three types of cross-sections, including rectangular, convergent parabolic, and divergent parabolic, for the shape of the fins have been studied. For this simulation, the three-dimensional, incompressible, and steady flow was considered, and for analysis and discretization of convective heat equations, the characteristic-based method was applied. FORTRAN software was also used to implement and solve the equations. The results show that in solid and interrupted fins and increasing the number of fins in parallel, the dimensionless heat transfer coefficient increases. Also, the dimensional heat transfer coefficient decreases with increasing the ratio of fin height to the tube’s diameter. Also, the most significant heat transfer improvement was related to the divergent parabolic cross-section.

Mining activities are one of the essential environmental challenges. Rating the environmental components (ECs) that affect by mining activities is a strategic guide for Environmental-Impact-Assessment (EIA). VlseKriterijumska- Optimizacija- I- Kompromisno- Resenje (VIKOR) method is developed as an efficient decision-making method to assess the impacts of the granite quarry Boog (in Southeast of Iran) on the environment. VIKOR method focuses on quantifying the effect of each impacting factor (IF) on each designed EC. This paper represents an evaluation method relying on fuzzy numbers in decision methods to carry out the lack of certainty and ambiguity from experts’ subjective knowledge and experience. Shannon entropy theory is used to adjust subjective weights defined by decision makers to objective weights. The results catched through ranking the R, S and Q indices. In this case, the Air quality (R= 0.05, S= 0.16, Q= -0.05) is available as the more important EC that affected by the mining activities contaminations. Compareing the results with standard matrix method confirm that the Air quality has been effected more than the other parameters with 33.63%. Fuzzy-VIKOR is a systematic approach, which can easily extend to deal with quantitative environmental analysis and other mining engineering selection problems.