International Journal of Engineering
Volume:35 Issue: 5, May 2022

So far many studies have focused on the mechanical behavior of fibre reinforced soils and stabilised soils with conventional chemical stabilisers such as cement and lime, however very limited researches were conducted on the unconfined compressive strength characteristics of fibre reinforced cement stabilised peat soils. Fibre-reinforcement of a stabilised soil resulted in a significant improvement in the ductility and strength characteristics of weak or soft soils. The main objective of the current study is considering the effects of cement content, fibre content, fibre length and curing time on the unconfined compressive strength (UCS) of peat soil. The study finds that adding basalt fibre or cement causes a remarkable increase in the UCS values of peat soil. The UCS value of the cement-stabilised sample is observed significantly more than basalt fibre-reinforced ones. However, the sample reinforced with basalt fibers showed more ductile behavior compared to the stabilised sample with cement. The results showed that the increase in UCS values of combined basalt fibre and cement inclusions was more than the increase caused by each of them, individually.

A new three stage production-assembly problem is considered in this paper. To the best of our knowledge, considering parallel machines in the third stage, identical parallel factories including the three stage production-assembly system and identical parallel factories with parallel machines in the third stage of the production-assembly system, only has been investigated in this paper. To minimize the maximum completion time (Makespan) of all jobs in the all factories, jobs assignment to factories and their processing sequence should be done properly. A Mixed Integer Linear Programming (MILP) model is presented to solve small size problem by using cplex solver. According to the problem computational complexity, large size of problem is not possible to solve using the cplex, so to solve it and to control the computational complexity, a new improved genetic algorithm (GA) is proposed by combining genetic algorithm and Longest Proseccing Time (LPT) method that is called Hybrid Genetic Algorithm Longest Proseccing Time (HGALPT). The problem parameters values are determined using one-way analysis of variance (ANOVA). Finally, in order to evaluate the efficiency and effectiveness of the proposed algorithm, and to specify each parameter impact on the objective function, sensitivity analysis is performed on the problem parameters.

In this paper, the cloud-computing model proposed by Davis has been used to explain the main parameters of cloud computing by users of information systems. This paper investigates effective factors on the decision to use cloud computing among employees of the national bank information technology organization based on the cloud-computing model. To achieve the aim of analyzing and investigating the use of cloud computing in national bank services, the designed questionnaire was distributed among the 230 experts and acquainted with the information technology industry in the national bank information technology organization, which resulted in the questionnaire’s Cronbach's alpha 0.84. After conducting exploratory and confirmatory factor analysis, with regard to analytical coefficients, utility factors were proved the most important influencing decision on the decision of cloud computing in the electronic banking system. Findings of this research can be considered as guidelines used by national bank managers to make use of cloud computing technology.

Clay soil may be subjected to heat in various applications, such as nuclear waste burial sites and high voltage transmission lines. The impact of heat on clay soil's physical and mechanical properties has been explored in previous studies. However, the previous studies have mainly focused on the mechanical properties of clay soil without stabilizers, and the effect of heat on the properties of stabilized clay soil is scarcely studied. The present paper has analyzed and studied the combined effects of heat and cement on the settlement properties of kaolinite clay soil. To conduct the study, kaolinite clay mixed with various degrees of cement was exposed to a range of 25 to 600 degrees Celcius. The results showed that the coefficient of consolidation gradually decreased by increasing heat up to the dehydroxylation point. An increase of heat up to 200 degrees Celcius resulted in increasing the coefficient of consolidation in the specimens containing cement. In specimens containing 10 percent of the cement in temperatures higher than 200 degrees Celcius, the coefficient of consolidation in room temperature decreased by 73 percent compared to kaolinite. Moreover, the void ratio increased in kaolinite specimens without cement when subjected to heat up to 400 degrees Celcius. The void ratio decreased in specimens containing 10 percent cement by increasing heat.

Instability of voltage is a problem that has been occurring in recent years due to excessive exploitation from equipment and an increase in demand for load across the distribution system. Shortage of the reactive power in the power networks, especially distribution networks, pushes the system toward voltage instability and leads to voltage drop as well as voltage fluctuations in the feeder. One of the potential solutions for compensation is to install thyristor switched capacitor (TSC). Although TSC can reduce the total costs of compensation, the static error will reduce compensation. For this purpose, an active power filter (APF) can be applied to resolve errors resulting from TSC due to features of continuous compensation and quick dynamic response. In this research, the combined method was presented, including TSC and APF of a controllable active power injection and with appropriate switching based on the study of voltage drop in the radial distribution networks and improvement of power quality. The suggested model was executed by MATLAB software, whereby results of improvement and provision of the stability conditions (dynamic and static) of voltage and current were observed.

In the present study, the fouling performance of a circumferentially corrugated tube was probed due to the air injection. The molasses of sugar beet was considered as the working fluid. The tube was considered to be under constant heat flux. Also, the flow rate of the molasses of sugar beet was considered to be constant. Five different flow rates of the airstream were considered to check the effect of airflow rate. The flow rate of working fluid was kept at the constant flow rate of 2 lit/min. The tests were conducted for 5000s (84 minutes). For a better understanding of the nature of the flow, the structure of two-phase steam was recorded via a Canon SX540 Camera. The results presented that the air injection in the corrugated tube will completely change the structure of the working fluid which will bring a very turbulent structure for the working fluid. The thermal results presented that during the testing time, the air injection will keep the heat transfer coefficient about 120% higher than a single-phase stream. The mass evaluation results revealed that the air injection could decrease the weight of fouled substance up to 75%.

This paper reports a novel curve generated by a point attached to an ellipse as it rolls without slipping along a datum line of rack cutter. A mathematical model of the non-circular gear profile has been developed based on the theory of gearing. The effect of an axial ratio  (the ratio of the lengths of the major and minor axes of the ellipse) and the position of the point KR, at which the novel curve starts to generate on the tooth shape and the undercut of the non-circular gear pair is also taken into consideration. A numerical program developed from the mathematical model has been proposed for the calculation and design of the non-circular gears (NCGs). Case studies were presented to show the steps of tooth shape design and to examine the geometrical profile of the NCGs in relation to design parameters of the rack cutter etc. From that, the axial ration  and position of the point KR on the generating ellipse ƩE can be selected for each specific case in order to design the appropriate profiles of the NCGs. On that basis, an experiment to determine the gear ratio of the NCGs pair based on the meshing between gears has manufactured.

This paper analysis heat transfer and angular velocity of micropolar ethylene-glycol nanofluid over the triangular, rectangular and chamfer fins on the stretching sheet. The innovation of this paper is to investigate parameters of nanofluid flow passing from the different fins on the stretching surface. The finite Element Method is selected for solving governing equations. The nanofluid temperature in the space of fins is warm and equal to the surface temperature. The temperature value is 30 degrees. The maximum values of nanofluid temperature exist in the last fin of surfaces. By passing the nanofluid flow from the first fins of the surface, the temperature of flow comes from 25℃ to 31℃  and at the ends of the surface, the temperature is high value. The maximum of ethylene glycol angular velocity occurs at x=0.9 for chamfer and rectangular modes and the minimum of temperature occurs at x=0.8 for 3 different fins. The angular velocity for nanofluid on the triangular and chamfer modes is 6.5% bigger than other baffles.

Modification of bitumen allows an improving the properties of bitumen, which can be a useful technique to enhance asphalt’s characteristics. Therefore, this research intended to study the effect of mixing time of different percentages of epoxy resin, between 0 to 8%, doped into bitumens on the moisture sensitivity of asphalt compounds containing two types of aggregates, i.e. limestone and siliceous. For this aim, the Sessile Drop Method (SDM) was employed, and moisture resistant parameters associated to surface free energy concept such as surface free energy components, work of cohesion, work of adhesion, work of debonding, adhesion bitumen to aggregate, and wetting bitumen around aggregate surface were assessed. The results revealed that the effect of the mixing time of bitumen and epoxy resin on moisture resistance properties of asphalt compounds significantly depends on the percentage of epoxy resin used in bitumen mixture. For bitumens with 4 and 6% epoxy resin, adhesion and wetting parameters had a similar performance for both mixing times of 10 and 60 minutes.  However, asphalt compounds containing 2 and 8% epoxy resin modified bitumens prepared for 10 min mixing time had a better adhesion and wetting performance than those prepared for the longer mixing time, 60 minutes.  The effect of mixing time of bitumen modified with epoxy resin on the bitumen and asphalt compound’ performance depend on the percent of additive in the bitumen.

Many factors play a role in the life cycle of construction industry projects, focusing on human resources and relationships as the main axis of business development. Thus, the conflict of interests between the stakeholders in the construction industry projects is a clear and challenging problem. The increased number of stakeholders in the project complicates human relationships and, consequently, increases the possible conflicts. The conflicts may result in claims if not resolved. The success of construction projects and their cost and time management can be affected by the poor management of claims. Therefore, this research aims to take a significant step to improve the efficiency of projects by identifying and ranking the causes of claims and analyzing their effects on key efficiency indicators. Firstly, causes of claim are collected according to experts’ opinions and literature and classified based on key efficiency indicators using the integrated analytic hierarchy process-technique for order preference by similarity to ideal solution (AHP-TOPSIS) technique. According to findings, delays with a proximity coefficient of 0.728 are the most significant factors in making claims with a great effect on the key efficiency indicators of the construction project. The changes in most construction projects are ranked in second place, followed by acceleration command, extra work, changing workshop conditions, and contractual ambiguities. The present study results may reduce the challenges in managing the construction industry claims and ensure the successful completion of projects.

This paper presents an idea for limiting the phase-shift angle in Dual Active Bridge (DAB) which ensures the converter’s stability. The stability is the main criterion in a converter’s operation without which the converter will stop working. In an ideal DAB which comprises of ideal components, the phase-shift angle limit is 90o. We developed a detailed model in Matlab/Simulink for DAB based on which the limits for the stable operation of converter are derived. In the developed model, attempts are made to employ as accurate as possible models for the components. In this way, the limits are expected to be very close to the practice. The DAB is a bi-directional converter; meaning that the power flow occurs in both forward and reverse directions. We derived the limits separately for forward and reverse modes. It is shown that the limits are the same for both directions confirming the fact that the DAB is symmetrical. We employed the DAB as the SuperCapacitor (SC) energy storage’s interface in this paper.

Considering the characteristics of the Caspian Sea waves, using a centipede wave energy converter might lead to satisfactory performance. The present paper introduced a pilot wave energy converter (WEC) called IRWEC2. Moreover, the performance of the hydraulic power take-off (PTO) system developed for the WEC was assessed experimentally in the wave tank of Babol Noshirvani University of Technology (BNUT). The Simcenter Amesim software was used so as to design the hydraulic PTO system and to initially evaluate the system performance. For two separate buoys were used, different series and parallel configurations were employed for the separate hydraulic cylinders connected to each buoy to achieve the optimum performance of the PTO system. The characteristics of input wave, resistant load, and flow control valve opening were defined as the most important parameters affecting the converter performance. Accordingly, the maximum value of generator output was obtained based on the certain values of these parameters. To validate the processes defined, the simulation results obtained through the Simcenter Amesim software were compared to the experimental ones and a good agreement was found. According to the results, the maximum power of the PTO system was 46 watts (for laboratory scale), which is related to the parallel configuration. In this case, the efficiency of the PTO system was 23%. Moreover, the output of the generator increased by about 12% compared to the case where only one buoy was used.

Road construction and maintenance activities cause traffic congestions and delays and present challenges for ensuring the safety of both motorists and road workers. While urban areas are well-equipped with traffic devices, in the case of highways our chances to collect traffic data and control traffic flows may be limited. Then the use of a temporary Highway Traffic Management System seems to be a suitable solution. Although the impacts of its deployment are addressed by many theoretical studies and demonstrated on traffic simulation models, there are not many references dealing with field tests. We provide results of the practical evaluation of the temporary Highway Management System installed and tested on the main highway in the Czech Republic during the road works period. Before-after analysis of collected traffic data was performed to prove the importance and positive impact of the proposed solution. We demonstrate an over 20% increase in the capacity of the roadwork zone and an almost 30 seconds decrease in average delay for one vehicle Highway administrators can use the results to justify investments into the temporary deployment of mobile traffic management systems.

Due to rapid urbanization and industrialization, the construction of roads increases rapidly for easy and fast transportation. Adequate land is not available everywhere to construct good roads; hence, roads are forcefully built on locally available soil such as loose soil or expansive soil. In this paper, an experimental investigation was carried out on low plastic soil (LPS) to enhance engineering properties by using chemical soil stabilization (fly ash-based geopolymer). The design of flexible pavement thickness was carried out for conventional and stabilized soil material using IITPAVE software as per IRC 37 guidelines. The results show the feasibility of fly ash-based geopolymer significant enhancement of strength were observed in terms of unconfined compressive strength (UCS) for various curing days (0 to 128 days), California bearing ratio (CBR), and Resilient modulus (MR). The microstructural analysis via Scanning Electronic Microscope (SEM) and X-Ray Diffraction Analysis (XRD) was also reveling the formation of geopolymeric gel which leads to the dense matrix to soil mass. The flexible pavement thickness significantly reduces with the application of stabilized low plastic soil.

Concrete has good strength and durability; however, it suffers from spalling and significant reduction of strength when exposed to fire. This study was aimed to enhance the fire resistance of concrete by applying two different techniques: 1) reinforcing with fiber, and 2) applying a fire-proof coating. For this purpose, mixes were made with steel fiber (SF), glass fiber (GF), and polypropylene fiber (PPF) applied at 0.5-2% of cement weight; in addition to a mix prepared with a 15 mm layer of fireproof coating material and a control mix. All mixes were subjected to elevated temperatures of 200-800 °C, and physical and mechanical properties were evaluated. According to the test results, both techniques were effective in enhancing the fire resistance of concrete mixes. The maximum residual compressive and flexural strengths were obtained for mix containing 0.5% GF, which were 117% and 145% higher than that of the control mix at 800 °C, respectively. Also, concrete with fireproof coating showed up to 76% and 113% higher compressive and flexural strengths compared to that of the control mix, respectively. It was found that addition of fibers in the manufacturing process of the concrete is a more desirable and economically-efficient approach to enhance the fire resistance. However, for an existing concrete structure, applying fireproof coating is the only option and can enhance the fire resistance comparably.

Beam-Column Joints (BCJ) manage the structural behaviour and failure mechanisms under severe events, blast, earthquakes, and impacts. Thus, they are the critical constituents in a building. Disparate deficiencies, say beam weak on flexure, shear, and column weak in shear, are present in this joint assembly to account for limits in design rule. To analyze the Reinforced Concretes (RC) Beam-Column (BC) connections behaviour, systematic research was performed amid the past '20' years. The influence parameters in favor of the Shear Strength (SS) of external RC-BCJ are investigated here. (a) The Concretes Compressive Strength (CCS), (b) confinement joint by the beam, (c) anchorage length, (d) beam and column reinforcement, and (e) the columns axial load are the '5' main parameters intended for the joint SS, which is found through the outcome. The most considerable correlation to the joint SS was found with the CCS amongst the influence aspects. This study reveals the vital features of the RC-BCJ shear strength.

Microchannel heat sink has been employed and as a part of electronic equipment extensively investigated. In this investigation, heat transfer and fluid flow features of laminar flow of water in a manifold microchannel heat sink (MMHS) was numerically simulated. Selected heat flux was 100 W/m^2 and water was as working fluid. The effect of length of inlet/outlet ratio (λ=Linlet/Loutlet), the height of microchannel (Hch), and width of the microchannel (Wch) at Reynolds number (Re) range from 20 to 100 as independent parameters on the fluid flow and heat transfer features were examined. Obtained results demonstrate that in MMHS, the impinging jet on the bottom channel surface, inhibits the growth of hydrodynamic and thermal boundary layers, resulting in an enhanced heat transfer rate. Also, by increasing Re and keeping the geometric parameters constant, the heat transfer rate increases. Based on the present investigation, for low Re, it is better to choose a λ=Linlet/Loutlet >1 and for high Re, choose a λ<1. For low Re, maximum of performance evaluation criterion (PECmax) is obtained at Hch=300µm, and for high Re, PECmax is obtained at Hch=240µm. for Re=20 to 100, the maximum of PECmax is 1.765 and obtained at Re=100 and Hch=240µm.

Past studies show that until now the Random Vortex Method (RVM) has only been used to solve the flow of Newtonian fluids. In this paper, by presenting a new approach, the RVM is developed for the first time with the aim of simulating the flow of non-Newtonian fluids. For this purpose, a numerical simulation of two-dimensional flow of non-Newtonian power-law fluid in a T-junction is presented. The simulation is conducted for Re = 50-200 at the inlet of the channel and different power-law indexes (n = 0.2-1.4). The RVM solves the Navier–Stokes equations as a function of time and determines the velocity at any point of the channel directly and without determining a mesh on the geometry. Potential velocity, an initial condition for the flow analysis by the RVM, is obtained using the Schwarz–Christoffel conformal mapping. The effect of two parameters of power-law index and Reynolds number on the recirculation zone has been investigated. Acceptable agreement among the results of the present study and the existing numerical and experimental results shows the capability of the proposed method, according to which the RVM can be considered a powerful promising method in simulating the non-Newtonian fluids in laminar and turbulent flow regimes.

In Central Vietnam, the traditional materials for making concrete are usually of natural origin. The overexploitation of these materials causes many adverse effects on the natural environment. Local industrial plants and quarries generate millions of tons of waste products such as fly ash and stone powder. However, when used for the partial replacement of cement and sand, these waste products can affect the compressive strength of concrete. Therefore, it is necessary to build models to predict compressive strength for this type of concrete. The paper aimed to apply artificial neural network models to predict the compressive strength of concrete using fly ash and stone powder waste products. The input of the ANN model includes six parameters: ultrasonic pulse velocity, wave amplitude attenuation ratio, and 4 parameters of concrete materials. Experimental data were obtained from 72 cubic specimens of different mixtures using available materials in Central Vietnam. These models allow predicting the 28-day compressive strength of concrete within the range of 9-62MPa (90-620daN/cm2). Furthermore, these models can predict compressive strength with any mixture. It is significant when re-evaluating whether the actual compressive strength value is as reliable as the one provided by the manufacturer.

The hollow glass microspheres (HGMS) has been recently used in the fabrication of low-density polymeric composites due to rather high stiffness nature of the fillers together with their lightweight that in turn results in the development of micro-composites of engineered properties with enhanced mechanical properties. Interfacial interactions at the filler/polymer interface control the load transfer and, thus, bulk properties of composites leading to unpredictable performance of composites embedded with inclusions. Nevertheless, useful analytical models are required to estimate the mechanical behavior of the HGMS based composites with the incorporation of the effect of interfacial interactions and possible agglomeration of fillers. No studies so far have reported the analytical modeling of HGMS reinforced thermosetting composites emphasizing the role of the interphase shaped at the vicinity of fillers.  This study aims at the fabrication of 0-20 wt% HGMS/polyester micro-composites followed by micromechanical modeling of the fabricated parts whilst the effect of the interphase region is emphasized by models modification. The results indicated a strong correlation between the interphase characteristics and Young’s modulus of the specimens revealing the dependency of the modulus on the thickness and modulus of the interphase as well as the level of agglomeration and interfacial debonding of the HGMSs. The results demonstrated that with considering no interphase, the models underestimate the modules of the parts, which suggests the presence of stiff interphase around the HGMS governed by changes in the interfacial cross-link density of the parent polymer as hypothesized supported by the mechanical response of the parts.

The aim of this study is synthesis of molecularly imprinted polymers (MIPs) and evaluation for extraction of catechin. Catechin is a bioactive compound which is found abundantly in green tea. In this paper, MIPs was synthesized by precipitation polymerization technique for catechin, acrylic acid and trimethylolpropane trimethacrylate as a template, functional monomer and cross-linker in a molecular ratio of (1:12:12), respectively. Surface morphology in the MIPs by scanning electron microscopy (SEM) demonstrated spheres with nanometric scale. Fourier transform infrared spectroscopy (FTIR) of the polymers showed that catechin molecule was captured in the network copolymers. Porosity of the polymers were analyzed using Brouneur Emmet Teller (BET) technique. Based on BET analysis, specific surface area of the MIPs was 45.5 m2.g-1 while it was 42.2 m2.g-1 for non-imprinted polymers (NIPs). It means that the imprinting process was carried out successfully. Adsorption properties of the polymers were characterized too.  The best binding capacity of the MIPs was reported equal to 440 mg. g-1 in 750 ppm of the feed concentration whereas it was 84mg.g-1 for quercetin (similar structure of catechin). It confirms that the MIPs technology can be introduced as a good candidate for separation process with a satisfactory result in selectivity. The binding capacity of the MIPs was evaluated for natural extract of green tea using a high-performance liquid chromatography (HPLC) device which similar results were obtained. According to above mentioned results, separation and pre-concentration of the bioactive compounds from the extract of medicinal plants can be suggested via MIPs technique.

Optimum design of sound absorbers with optimum thickness and maximum sound absorption has always been an important issue to noise control. The purpose of this paper is an achievement of optimum design for micro-perforated panel (MPP) and its combination with a porous material and air gap to obtain maximum sound absorption with maximum overall thickness up to about 10 cm in the frequency range of (20-500 Hz), (500-2000 Hz) and (2000-10000 Hz). For this purpose, the genetic algorithm is proposed as an effective technique to solve the optimization problem. By using the precise theoretical models (i.e. simplified Allard's model and Atalla et al.’s model) to calculate the acoustic characteristics of each layer consisting of MPP, porous material, and airgap, we obtained more precise optimized structures. The transfer matrix method has been used to investigate the sound absorption of structures. To verify the operation of the programmed genetic algorithm, the results obtained from the optimization of the MPP absorber are compared with others that show the accuracy and efficiency of this method. After ensuring the accuracy of the proposed programmed genetic algorithm with more precise theoretical models to achieve the characteristics of each layer, new structures were obtained that have a much better sound absorption coefficient in the desired frequency range than the previous structures. The results show that the sound absorption coefficient can be reached to 0.67, 0.96, and 0.96 in the mentioned first, second, and third frequency range, respectively by optimum design parameter choosing of a composite structure.

Outsourcing as a useful strategy in the industry can be integrated into scheduling problems. Moreover, batch outsourcing is a practical assumption owing to the logistics issues for transferring the parts between the manufacturer and the subcontractors. However, this assumption is rarely addressed in the scheduling literature. In this paper, a novel single machine scheduling problem with the option of batch outsourcing is studied. The objective is to minimize the sum of the total completion time of the jobs and the total outsourcing cost. To solve the problem, first, two mixed-integer linear programming (MILP) models, named MP1 and MP2, are developed, which respectively use a straightforward and an innovative approach to model the outsourcing batches. Next, an optimal property for the outsourcing batches is proven. This property is used to establish a valid inequality for model MP2, which is added to it to obtain a third MILP model, MP3. Extensive computational experiments showed that MP2 outperforms MP1 significantly. Moreover, including the derived valid inequality in MP3 enhances its performance considerably in comparing to MP2. Furthermore, it is observed that MP3 is capable of solving many practical-size problem instances optimally or with a low maximum optimality gap.

It has become necessary to use damaged tires from various vehicles to produce rubberized concrete structures as a good solution to treat environmental pollution and reduce the total cost of construction. In general, concrete structures, for many reasons, may need to be strengthened. Recently, fiber-reinforced polymer (FRP) sheets have been used to reinforce existing concrete structural elements that were deficient. FRP is an effective solution and is moderately common for strengthening and improving the properties of the structural element. Firstly, concrete mixes were poured with replaced sand, with the percentages varying from 0, 10, 20, and 30%. Thus, some mechanical properties in terms of the workability of concrete, compressive strength, tensile strength, and density of recycled concrete were studied using rubber from tires as an alternative to fine aggregate. Secondly, concrete prisms were poured with different proportions of rubber instead of sand. Twelve rubberized concrete prisms measure 100 mm x 100 mm x 600 mm. Then, the effect of fiber reinforced polymer with different forms on concrete prisms was investigated. The results revealed a decrease in the workability, density, and compressive strength of the rubber concrete samples with an increase in the proportions of replaced sand with rubber content. It is also observed that FRP improves the strength, stiffness, and ductility of all concrete prism beams with a different ratio of recycled rubber. In addition, the test results clearly show that the strengthening by width sheets of FPR behaved more favorably than the thin sheets having the same cross-section.