International Journal of Engineering
Volume:34 Issue: 4, Apr 2021

In recent decades, Iran has been facing severe water deficiency. In all countries, industrial plants are the most water-consuming sectors; thus, industrial wastewater treatment is always a essential subject. Nitro-Toluene derivatives are extensively used in industries, especially the military industry, which itself has an abundant share in industrial wastewater contamination. These compounds are extremely dangerous for living beings and can have irreparable effects, so eradication of them in industrial wastewater is necessary. Photocatalytic processes are one of the particular approaches in industrial wastewater treatment from the advanced oxidation processes subdivision. One of the prominent and most widely used photocatalysts in this process is Titanium Dioxide (TiO2) . This research aims at the investigations for the modification of  TiO2/Bentonite (TB) catalysts for attaining more economical saving and degradation stabilization conditions. To achieve this goal, the Bentonite and TiO2 photocatalyst was synthesized by a co-precipitation procedure, and its catalytic activity on Para Nitro-Toluene (PNT) degradation was examined. The designed TB photocatalyst is made of 5, 10 and 20 % of TB. A suspension reactor and the spectrophotometry was applied for specifying the extent of the degradation. Characterization of modified catalyst was conducted by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and energy dispersive X-ray (EDX). The results highlight that with increasing TiO2 percent, degradation rate augmented, and the highest degradation was attained for TB 20% at 59%. However, Under the same conditions, for pure TiO2, the degradation rate is 64%, but with more TiO2 consumption and time. Finally, in order to further confirm the extent of the degradation, chemical oxygen demand (COD) test was performed on the TA20 sample. The results showed that about 53% of PNT has been converted to minerals.

The present study evaluates the risk of the gasoline tank of the National Iranian Oil Product Distribution Company (NIOPDC) in Sari region using process hazard analysis software tool (PHAST) and according to the environmental and process data of the unit. The consequences of different scenarios such as small and medium leakage, constant release rate and complete rupture were modeled and then the range of each one was obtained according to the intensity of radiation or pressure wave and the safe distances of each was determined. Due to the consequences of the explosion, the worst results were related to the weather conditions of 2/3 F for 4700, 2400, and 2300 meters, respectively. Also, based on eruptive and sudden fire data, the intensity of radiation which corresponds to the immediate death or destruction of equipment was seen in climatic conditions of (2/3 F and 4/1 D), at intervals of 180 and 160 meters distances, respectively. In these two weather conditions flammability intervals were 10520 and 450 meters. Then, by combining the severity of these accidents with the distribution of the population and the probability of their occurrence, the level of risk for these storages was determined.

This research describes an optimization and rejuvenation of the heat treatment process for a nickel base superalloy grade GTD111 after long-term service. The aging heat treatment variables examined in this study included primary aging temperature, primary aging time, secondary aging temperature, and secondary aging time. The resulting materials were examined using Taguchi method design of experiments to determine the resulting material hardness test and observed with the hot tensile test, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The experimental results showed what happens following optimization with the heat treatment parameters of a primary aging temperature of 1120 °C, primary aging time of 3 h, secondary aging temperature of 845 °C, and secondary aging time of 24 h. The material, after rejuvenation heat treatment via optimization with γ′ particle characteristics, had a coarse square shape, spherical shape of γ′, and fine γ′ precipitate distributed on the parent phase, which affects the mechanical properties of the material. fine γ′ precipitate distributed on parent phase, which affects the mechanical properties of the material.

The external post-tension technique is one of the best strengthening methods for reinforcement and improvement of the various steel structures and substructure components such as beams. In the present work, the load carrying capacity of the post-tensioned tapered steel beams with external shape memory alloy (SMA) tendons are studied. 3D nonlinear finite element method with ABAQUS software is used to determine the effects of the increase in the flexural strength, and the improvement of the load carrying capacity. The effect of the different parameters, such as geometrical characteristics and the post-tension force applied to the tendons are also studied in this research. The results reveal that the external post-tension with SMA tendons in comparison with the steel tendons causes a significant improvement of the loading capacity. According to this, using SMA tendon for the reinforcement of the tapered beams causes a decrease in weight of these structures and as a consequence causes economic benefits for their application. This method can be used extensively for steel beams due to low executive costs and simplicity of the operation for post-tension.

Concrete structures retrofitted with fiber reinforced cementitious matrix (FRCM) have become widespread due to their mechanical and durability performances. However, the behavior of FRCM -strengthened RC members under service loads is still a concern, and more efforts need to be done. In this study, a nonlinear three-dimensional finite element (FE) model has been developed to study the performance of reinforced concrete (RC) beams strengthened by (FRCM). The model was validated against the experimental results gathered from six beams tested under three-bending points. Consequently, the primary numerically studied parameters were longitudinal steel reinforcement ratio and concrete compressive strength. A cohesive damage parameters were investigated to represent the experimental results. Also, the theoretical flexural capacity of strengthened beams based on ACI-549 code was evaluated based on the numerical method results. As a conclusion, the numerical results are in a very good agreement with the experimental ones regarding yielding load, ultimate load, and failure mode. In addition, the developed models from parametric studies concluded the insignificant effect of concrete compressive strength on increasing the ultimate capacity of strengthened beam. However, the steel reinforcement ratio has a major impact on enhancing the ultimate capacity of strengthened beams.

Timber apart from being a cheap construction material possesses numerous environmental advantages, which makes it one of the highly sought construction material, particularly for moderately loaded residential structures. Timber due to the easy cultivation of timber trees can be made available in abundance. Thus, can serve as an efficient and sustainable building material, provided its structural potential is tapped fully. In this study, various performance improvement techniques have been used for enhancing the axial strength characteristics of a timber specie (Poplar), that is available in abundance, in the northern part of India. Different binding/wrapping techniques have been adopted to utilize Poplar in a laminated form, known as cross-laminated timber (CLT). It has been found that a strength improvement of about 20% can be achieved in CLT short columns by simply bolting the laminates together, while as this improvement can be as high as 32%, provided cold form steel (CFS) sheets are used for strengthening these CLT timber columns. Similarly, in the case of long CLT columns, a strength improvement of 50% is attained when a double cross helix of fibre reinforced polymer (FRP) cloth is adopted for the strengthening purpose. Furthermore, this study is aimed at utilizing small unused, otherwise, waste timber logs/pieces in columns with strength improvement techniques for improved axial strength performance.

Cybersecurity has turned into a brutal and vicious environment due to the expansion of cyber-threats and cyberbullying. Distributed Denial of Service (DDoS) is a network menace that compromises victims’ resources promptly. Considering the significant role of optimization algorithms in the highly accurate and adaptive detection of network attacks, the present study has proposed Hybrid Modified Grasshopper Optimization algorithm and Genetic Algorithm (HMGOGA) to detect and prevent DDoS attacks. HMGOGA overcomes conventional GOA drawbacks like low convergence speed and getting stuck in local optimum. In this paper, the proposed algorithm is used to detect DDoS attacks through the combined nonlinear regression (NR)-sigmoid model simulation. In order to serve this purpose, initially, the most important features in the network packages are extracted using the Random Forest (RF) method. By removing 55 irrelevant features out of a total of 77, the selected ones play a key role in the proposed model’s performance. To affirm the efficiency, the high correlation of the selected features was measured with Decision Tree (DT). Subsequently, the HMGOGA is trained with benchmark cost functions and another proposed cost function that enabling it to detect malicious traffic properly. The usability of the proposed model is evaluated by comparing with two benchmark functions (Sphere and Ackley function). The experimental results have proved that HMGOGA based on NR-sigmoid outperforms other implemented models and conventional GOA methods with 99.90% and 99.34% train and test accuracy, respectively.

The routing protocol of IPv6 for lossy and low power networks (RPL) was approved in March 2012 by Internet Engineering Task Force as the standard routing protocol for the Internet of Things (IoT). Since that time, it has had various applications in IoT. Despite meeting the IoT network necessities by RPL, there are yet some unanswered issues as it has not been devised primarily for IoT usages. Although gathering a large amount of data from these networks with videos and images typically leads to traffic congestion in the central part of the network. For providing a solution for this issue, the content-centric routing CCR-based RPL is proposed in the present study, where the routing pathways are specified by the content. With routing the relevant data to the middle relaying nodes for process, it is possible to attain a larger data aggregation ratio. Thus, effective traffic is generated in the network. Subsequently, latency is significantly reduced. Moreover, energy use is principally decreased on wireless communication. Therefore, the restricted battery is preserved. More integration was conducted between IETF RPL protocol and CCR, applying in the MATLAB platform. Finally, according to simulated and implemented results, the CCR-based RPL behavior based on the high packet transfer rates is better, and the numbers of dead nodes are reduced, and high energy efficiency and low delay rates are obtained in the transfer.

Federated Learning enables aggregating models trained over a large number of clients by sending these models to a central server, while data privacy is preserved since only the models are sent. Federated learning techniques are considerably vulnerable to poisoning attacks. In this paper, we explore the threat of poisoning attacks and introduce a game-based robust federated averaging algorithm to detect and discard bad updates provided by the clients. We model the aggregating process with a mixed-strategy game that is played between the server and each client. The valid actions of the clients are to send good or bad updates while the server can accept or ignore these updates as its valid actions. By employing the Nash Equilibrium property, the server determines the probability of providing good updates by each client. The experimental results show that our proposed game-based aggregation algorithm is significantly more robust to faulty and noisy clients in comparison with the most recently presented methods. According to these results, our algorithm converges after a maximum of 30 iterations and can detect 100% of the bad clients for all the investigated scenarios. In addition, the accuracy of the proposed algorithm is at least 15.8% and 2.3% better than state of the art for flipping and noisy scenarios, respectively.

Digital images watermarking is a method for data hiding that ensures the security of multimedia data. In these ways, a watermark can be a digital image or data stored within digital content. The Shearlet transform, a multi-resolution and multi-directional conversion, can be used for watermarking in digital images. Due to its superior features, this conversion can increase the efficiency of applications such as watermarking of images. In this paper, Shearlet and SVD transforms are used with the Whale optimization algorithm to obtain the most appropriate scaling factor in the watermark extraction step after applying different types of image processing attacks. Shearlet Transform has more transparency than traditional converts. The SVD transform also increases the robustness of watermarking operations. The results of different experiments show that the new method presented in this paper, in terms of robustness and imperceptibility compared to the methods tested, performs better than most image processing attacks.

Traffic congestion and route guidance are integral parts of urban development in large cities. How cars are routed and the traffic flowing have a direct impact on each other. Therefore, the first step is to determine a criterion for assessing the traffic situation. The type of vehicles should also be considered in routing. Emergency vehicles must arrive at their mission site as soon as possible. Public transportations must also travel according to their plans. Ordinary vehicle drivers can either choose a road as an intermediate destination (out of interest, pick up someone, etc.). In this paper, two new algorithms are proposed to 1) route with intermediate destination selection for ordinary vehicles, and 2) schedule traffic lights to decrease traffic density and routing delay. The first algorithm proposed an agent-based route guidance model that in addition to finding the least expected travel time (LET) routes, drivers could select a part of the route as intermediate destinations according to their interests, to raise their satisfaction level. The second algorithm considers the density of traffic flow and the presence of emergency vehicles. This algorithm evaluates the status of the traffic flow by fuzzy logic. The evaluation is conducted by considering traffic flow speed and density. The output of fuzzy logic is used by the Gradational Search Algorithm (GSA). GSA regards the status of the flow, the priority of the traffic flow, and the distance of the emergency vehicles to the traffic light. The simulation results prove that the proposed algorithms have better performances.

In this paper, two protocols are presented for private intersection detection of two moving objects’ trajectories. Assuming that the movement trajectory of an object can be described by a time-dependent polynomial function, the problem of finding the intersection points is simplified to the problem of finding the common roots of the corresponding polynomials. Thereafter, GrÖbner Basis is used to design a novel secure protocol of finding the common roots of the polynomials. Another protocol is also designed based on the distance computation of two trajectories’ curves. Moreover, we present the complexity analysis of the protocol for private trajectory intersection testing of two moving objects, which is based on GrÖbner Basis. Then, we compare its complexity by the garbled circuit-based protocol for Euclidean Distance Computation of l points. We also prove the security of our proposed protocol, which is based on the distance computation of two curves. Keywords: Private Trajectory Intersection Testing, GrÖbner Basis, Distance Computation, Complexity , Garbled Circuit, Euclidean Distance

Recently, the utilization of hybrid organic-inorganic perovskite solar cells under advanced light management designs have attracted intensive attention.  In this study, a three-dimensional (3D) finite element method (FEM) technique was used in the COMSOL Multiphysics simulation package to investigate coupled optical and electrical characteristics of perovskite solar cells (PSCs) with light trapping nanostructures. Upon the use of nano-textured fluorine-doped tin oxide (FTO) substrates, we propose two architectures which can guide and trap the light at nanometer dimensions. Two proposed PSCs i.e. concave and trapezoidal structures are compared to the planar structure in order to investigate the effects of using nanostructured substrates on the optoelectronic performance of PSCs. Optical analysis reveals that using optimized concave and trapezoidal structures can enhance the light absorption up to 32 and 26%, respectively at the wavelength of 550 nm. Electrical simulations have shown that in addition to enhanced total carrier generation, the generated carriers can be effectively collected in the proposed nanostructured PSCs. Accordingly, the short-circuit current has risen from 20 mA for planar structure to 25.7 mA for concave and 23.2 mA for trapezoidal PSCs. After analyzing various heights and adopting optimum values, the power conversion efficiency for concave and trapezoidal PSCs experienced substantial increase of 5.5 and 3.5%, compared to the planar structure. These drastic improvements analyzed by coupled optical and electrical modelling of nanostructures can pave the way for further studies to fabricate high efficiency PSCs with nano-textured substrates as a light-trapping technique.

Installation of Shunt Capacitor Banks (SCBs) and Voltage Regulators (VRs) within distribution system is one of the most effective solutions in reactive power control for improving the voltage profile and reducing power losses along the feeder. However, the presence of the VRs can deteriorate the Voltage Stability Margin (VSM) in distribution feeders. To address this issue, this paper proposes a multi-objective programming model for the simultaneous optimal allocation of VRs and SCBs in the distribution network to improve the voltage profile and to minimize power losses and installation costs. In the proposed model, a Voltage Stability Index (VSI) is considered to prevent voltage instability during SCBs/VRs allocation. A new Modified Multi-Objective Particle Swarm Optimization (MMOPSO) algorithm which includes a dynamic inertia weight and mutation operator is proposed to obtain the optimal solutions as a Pareto set. Thereinafter, a Fuzzy Satisfaction Method (FSM) determines the optimal solution. A practical long radial distribution feeder has been employed to demonstrate the efficiency and efficacy of the proposed model along with a comparison between the proposed MMOPSO and the original MOPSO.

One of the problems with today's TCP/IP networks is their transmission system. If the bandwidth of a network is full, human and physical factors must be used for a new transmission system with a higher capacity to provide its bandwidth, which is very time consuming and costly. In this article, we proposed a method that in addition to the optimal use of available bandwidth, if the network capacity is full, it will be automatically transferred to a higher bandwidth network. For this purpose first, by designing a fuzzy PID controller for the existing network, it is tried to congestion control them and make use of it. It can be seen that the proposed controller performs much better in terms of an output response, following the queue length, stability and uncertainly, compared to the classical controller. If the input data to the network is increased, more packets are lost and this reduces the quality of the network. To solve this problem by using bandwidth management, by considering the threshold for packets loss in each network, if exceeding this limit, the existing network is switched to a network with a higher capacity and the problem of bandwidth and network quality is solved and causes subscriber satisfaction.

One of the major problems in designing highly compact integrated circuits is the power consumption of the circuits. Therefore, several technologies have been introduced to overcome the problems facing MOSFET technology. One of these technologies is the Quantum-Dot Cellular Atomata (QCA), which has several advantages. In this paper, we focus on computational logic gates based on the T-Latch circuit. T-latch is the basis of many circuit in arithmetic logic unit (ALU). The proposed structure for T-latch has a lower number of cells, occupied area and lower power consumption than existing methods. In the proposed T-Latch, compared to previous best designs, 6.45% cross section area and 44.49% power consumption were reduced. Also in this paper, for the first time a T-latch with reset terminal and a T-Latch with both set and reset terminals were designed. In addition, using the proposed T-latch, a 3-bit bidirectional up-down counter which consists of 204 quantum cells, 0.26 µm2 cross-sectional area, delay of 5.25 clock cycles, a three-bit up-down counter with a reset pin and a three-bit up-down counter with set and reset terminals were made. The proposed up-down circuits are designed for the first time in QCA technology. All the design and simulation results are done in QCADesigner software.

Transverse flux permanent magnet machines (TFPMs) are categorized as synchronous machines that benefit from having high value of torque density and capablity of accommodating high pole numbers. These characteristics make TFPMs suitable candidates for low-speed applications where high torque density value is requred such as direct drive wind turbine application.  Despite the aforementioned advantages, TFPMs suffer from intrinsically high cogging torque value which is an important concern for wind turbine application. This paper focuses on axial PM segmentation technique to minimized cogging torque of TFPM topologies. Concept of the proposed method is discussed using analytical equations and optimum segmentaion angle is formulized. Non-linear magnetic equivalent circuit (MEC) is adopted where the PM segmentation, armature reaction, rotor transition and iron saturation effect are carefully modeled. The results of the MEC simulation are compared with the finite element method (FEM) results in terms of accuracy and computational time. The results from the analysis indicate that the proposed MEC method is almost ten times faster than FEM with reasonable level of precision. Taguchi method is adopted as a fast-response optimization method to improve the generator torque characteristics. The results show that the cogging torque has reduced by 97% with respect to the initial design while the average torque has only dropped by 8% which is an acceptable side effect due to the significant improvement in machine cogging torque.

The present paper shows the results of applying an artificial neural network to three non-destructive magnetic methods including magnetic hysteresis loop (MHL), eddy current (EC), and magnetic flux leakage (MFL) techniques to determine mechanical features of plain carbon steels with unknown carbon contents subjected to tempering treatment. To simultaneously evaluate the effects of carbon content and microstructure on the magnetic and mechanical properties, four grades of hypoeutectoid steel samples containing 0.30, 0.46, 0.54, and 0.71 wt.% carbon were austenitized in the range of 830-925 °C and then subjected to quench-tempering treatments at 200, 300, 400, 500 and 600 °C. In the next step, mechanical properties including tensile strength, elongation, and hardness were measured using tensile and hardness tests, respectively. Finally, to study the electromagnetic parameters, MHL, MFL and EC non-destructive electromagnetic tests were applied to the heat-treated samples and their outputs were fed to a generalized neural network designed in this work. The results revealed that using a proper combination of electromagnetic parameters as the ANN input for each mechanical parameter enables us to determine the hardness, UTS and elongation of hypoeutectic carbon steel parts after tempering treatment with high accuracy.

The surface texture on the EDM is an important quality indicator since it directly affects the cost of the further finishing work. The coating over the tool electrode in EDM can improve productivity, electrode wear resistance and surface quality. In the present study, the surface roughness of the EDM machined surface with coated and uncoated electrodes was evaluated. Al and AlCrNi coated Al electrode has been used for the study on machining Titanium alloy (Ti-6Al-4V). Current (I), voltage (Vg) and pulse on time (Ton) have been used as technology parameters under Taguchi method with regression model and optimal technology parameters. It was found as I and Vg are the parameters could strongly affect surface quality. The coated tool electrode can produce better surface quality than uncoated tool electrode. The optimal technological parameters with coated and uncoated electrodes were found as I = 10 A, Ton = 500 µs and Vg = 40 V.

This paper presents a predictive robust and stable approach for a two-machine flow shop scheduling problem with machine disruption and uncertain job processing time. Indeed, a general approach is proposed that can be used for robustness and stability optimization in an m-machine flow shop or job shop scheduling problem. The robustness measure is the total expected realized completion time. The expected sum of squared aberration between each jobs’ completion time in the realized and initial schedules is the stability measure. We proposed and compared two methods to deal with such an NP-hard problem; a method based on decomposing the problem into sub-problem and solving each sub-problem, and a theorem-based method. The extensive computational results indicated that the second method has a better performance in terms of robustness and stability, especially in large-sized problems. In other words, the second method is preferable because of the better manufacturer responsiveness to the customer and the production staff satisfaction enhancement.

Titanium carbonated hydroxyapatite (Ti/CHA) nanobiocomposites have extensive biological applications due to the excellent biocompatibility and similar characteristics to the bone. Ti/CHA nanobiocomposite has good biological properties but it suffer from diverse characteristics especially in the hardness, Young's modulus, apparent porosity and relative density. This investigation is an attempt to propose the predictive models using gene expression programming (GEP) for the estimation of these characteristics. In this regards, GEP is used to model and compare the effect of practical variables including compact pressure, Ti/CHA ratio and sintering temperature on their investigated properties. To achieve this goal, 90 different reliable experiments were considered to create the GEP models. Selected data set were divided randomly into 63 training sets and 27 testing sets. Finally, 5 of the best models reported for each different output. Sensitivity analyses are done to determine and rank the practical parameters on each investigated properties and revealed that wt.% Ti, wt.% CHA, Compaction pressure (MPa) and Temperature (ᵒC), respectively are the most effective parameters on hardness, Young's modulus, shear modulus, apparent porosity and relative density. By comparing the results, a very good agreement was observed between the experimentals and the results obtained from GEP model.

This research describes an optimization and rejuvenation of the heat treatment process for a nickel base superalloy grade GTD111 after long-term service. The aging heat treatment variables examined in this study included primary aging temperature, primary aging time, secondary aging temperature, and secondary aging time. The resulting materials were examined using Taguchi method design of experiments to determine the resulting material hardness test and observed with the hot tensile test, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The experimental results showed what happens following optimization with the heat treatment parameters of a primary aging temperature of 1120 °C, primary aging time of 3 h, secondary aging temperature of 845 °C, and secondary aging time of 24 h. The material, after rejuvenation heat treatment via optimization with γ′ particle characteristics, had a coarse square shape, spherical shape of γ′, and fine γ′ precipitate distributed on the parent phase, which affects the mechanical properties of the material. fine γ′ precipitate distributed on parent phase, which affects the mechanical properties of the material.

In this study, the design of experiments is used to study and model the time of passivation in copper electrorefining as a function of the charge of melting furnace through the preparation of copper casting anodes. As a result of optimization for the proposed optimized anodes, the charge percent values of concentrate (Co), refinery scrap (RS), and non-refinery scrap (NRS) were proposed equals to 69.1, 0.574 and 30.32 (wt.%), respectively. Experimental data confirmed the enhanced passivation time of the proposed anode was 6520 s. Also, it was observed that the molar ratio of As/(Bi+Sb) and Ag/(Se+Te) are the key factors in passivation time. Finally, the relation of passivation time (seconds) with the charge of melting furnace is proposed as:  t (s)= - 3728.98 × Co + 4640.00 × RS + 3141.00 × NRS + 17763.27 × Co × RS + 25547.65 × Co × NRS - 1758.00 × RS × NRS. Moreover, adding of As ingot in casting anodes as a dose dependent of non-refinery scrap portion in the input charge of the melting unit can effectively prolong the time of passivation.

Antifouling paints are applied to prevent the growth of marine biofouling. In Indonesia, that paint is widely used for ship which commonly used copper-based biocide. In fact, there is no or little comprehesive studies on antifouling paint in Indonesia compared to other tropical countries. In this study, the evaluation of the performance for antifouling paint was carried out where anticorrosion  paint and bare steel were also studied as references. The measurement of corrosion rate on steel was conducted by weight loss method. The panels containing specimens were exposure up to 1-month for immersion in different depth of sea up to 3 meters. Seawater parameters consisting of temperature, pH, salinity, conductivity and dissolved oxygen were measured as well as coating properties. The results showed both surfaces of anticorrosion paint and steel specimens covered by biofouling, but not on antifouling paint. There also is not much different in antifouling paint properties before and after exposure in various depth of sea. The reduction of thickness for antifouling paint is apparently predominant to be affected by sea current. The magnitude of corrosion rate on bare steel is almost the same in different depth of sea which took place due to the effect of dissolved oxygen and biofouling. In the future, the comparison of the paints perfomance all local regions is necessary to be conducted in all local regions of the Indonesia.

This paper presents an experimental study of addition of cellulose nanofibers (CNF) extracted by the chemical-ultrasonication process from agave cantala leaf plants in the matrix of polyvinyl alcohol (PVA). Combining these materials produce the nanocomposite film with a thickness of 30 μm. The nanocomposite characteristic was investigated by the addition of CNF (0, 2, 5, 8, and 10 wt%) in PVA suspension (3 wt.%). PVA/CNF nanocomposite films were prepared by a casting solution method. The fibrillation of fibers to CNF was analyzed using Scanning Electron Microscopy and Transmission Electron Microscopy. The nanocomposite film functional group's molecular chemical bond and structural analysis were tested using Fourier Transform Infrared and X-ray diffraction. The PVA/CNF nanocomposite film has significant advantages on the ultraviolet barrier, thermal stability tested by Differential Scanning Calorimetry and Thermogravimetric Analyzer, and tensile strength. Overall, the optimal addition of CNF is 8 wt.% in matrix, resulting in the highest crystallinity index (37.5%), the tensile strength and elongation at break was an increase of 79% and 138%, respectively. It has good absorbing ultraviolet rays (82.4%) and high thermal stability (365oC).

Aerospace structures are highly vulnerable to impact loads whose damage tolerance, and its resistance vary over the range of impact velocity. Honeycomb sandwich structures are used in aerospace industries where mass efficient and impact resistant structures are needed. However, the structural integrity of these structures is reduced by impact load due to tool drop, runway debris, hailstones and improper handling of the structure. A thorough investigation of the damage behaviour of honeycomb sandwich under low-velocity impact and the post-impact residual strength determination is required to design a crashworthy lightweight structure. This paper presents the experimental evaluation of specific energy absorption using Charpy impact, residual compressive strength by compression after impact and damage evaluation of honeycomb sandwich structures having composite face sheets. Parametric studies on composites and honeycombs are carried out by varying the cell size, cell thickness, core height, impact velocity, thickness and orientation of lamina. Densely packed thick honeycombs provide higher fracture energy. Under transverse compressive loading, the honeycomb core undergoes cell wall buckling, crushing and densification. Load-displacement history under in-plane compression and compression after impact for different impact energies is observed. The present study contributes for the understanding how various parameters affect the characteristics of face sheet indentation and plastic buckling of honeycomb sandwich structures with composite face sheets, thereby providing useful guidelines for its potential applications in impact engineering.

Active and passive methods are two main mechanisms of heat transfer improvement. The active methods use external forces to improve heat transfer. This investigation evaluates the thermal and frictional behavior of a circular tube containing a rotational shaft. Constant heat flux was exerted to the circular tube. The fluid inlet and outlet temperature as well as wall temperature of tubes were measured to calculate the hat transfer coefficient. The Re (Reynolds) number was between 800-2000. Also, the dimensionless rotational speed (Rs) had the values of 1,1.5, 2, 2.5 and 3. Results revealed that the rotational shaft could increase the Nu number. Up to %18. Also, the results showed that the rotational shaft could significantly increase the pressure drop and friction factor. The maximum increment of %78 was achieved for friction factor. It was revealed that the use of rotational shaft could be more efficient at low Re numbers and low dimensionless rotational speeds. Also, it was found that by the increment of Reynolds number and being in the transient regime the efficiency of the system would improve.

Due to the world increasing energy demands, optimizing the drilling system parameters such as the weight on bit (WOB), and the structure of drill string and bit, also vibrations and dynamic behavior of drill strings are of significant interest to researchers and energy industries. Specially, to overcome limitations of drilling operations in oil and gas industry, composite drill strings as high-tech devices are under development. In this research, the fully coupled non-linear axial vibrations of composite drill strings due to the interaction of two common bits namely; Roller Cone (RC) and Polycrystalline Diamond Compact (PDC) with rock, considering the major non-linear terms, the drill string-wellbore contact, the different weight on bit (WOB) and the different composite configurations using the finite element method (FEM) and the Lagrangian approach were studied. This study proved that the different configurations of composite drill strings showed specific dynamic behavior at different conditions. Therefore, composite drill string can be designed for particular purposes. Also, the results imply the remarkable effects of weight on bit (WOB) and type of bits on the axial vibrations of composite drill strings.

In the last thirty years, the friction stirs welding (FSW) process has achieved significant importance due to the satisfactory results derived from severe deformation and low heat input during the welded joint production. These elements have been considered to implement the FSW in different welded systems, including aluminum-steel joints. In these dissimilar joints, the main interest was to obtain a welded joint with acceptable mechanical behavior. Some papers recently focused on understanding dissimilar joints process, mainly on the metal flow and its response to corrosion. However, in Al-steel joints, the presence of steel particles in the nugget zone is routine, alters both the welded joint's mechanical and chemical behavior. Thus, this work aims to evaluate the mechanisms that govern these particles' generation, the effect of offset on their formation, and estimating the characteristics of the material flow, using the detached fragments as tracers. It was established that the offset controls the metal's fluidity, which allows the accumulation of steel fragments on the advanced side, in addition to reducing its quantity, due to the decrease of irregularities in the Al-steel interface. Likewise, the metal flow was observed on the retreating side, with that mentioned on aluminum joints. In contrast, on the advanced side, there is a shear action, push down, and lateral movement towards the retreating side, driven by the high forging strength of the metal and the restriction imposed by the steel and the backing.

In this study, effects of adding butene, homopolymer to gasoline on the performance of a four-stroke spark ignition (SI) engine and pollutant emissions have been investigated. This additive increases the octane number of gasoline. In this research, the additive was combined with a non-leaded gasoline. Also, in addition to fuel changes and the use of additives, engine spark plugs were replaced and three types of spark plugs were used for this study. These include single electrode spark plug, dual electrode spark plug and Platinum+4 spark plug. The results of experimental tests showed that with the addition of additive to gasoline, the brake torque and braking power were increased with the use of each of the three spark plug type. The results revealed that by combining gasoline and additive, carbon dioxide and nitrogen oxides emissions were increased. On the other hand, unburned hydrocarbons and carbon monoxide emissions from the engine were reduced. In addition, it was concluded that changing the spark plugs had slight effect on engine performance and pollutant emissions, and that the results of experimental tests using all three types of spark plugs were almost identical.

The maintaining stability of public facilities, especially public roads, it is very necessary, so the stabilization efforts must be carried out. The water from seepage that comes out of sandstone layer carries material with fine particles, it causes the rock cohesion to decrease and thus leading to scouring. As a result of the scouring, the layer becomes overstep and can disturb road stability. This study was conducted to provide simple but measurable recommendation for maintaining road stability after the previous stabilization effort failed. The method used a fluid mechanics approach in which water from the formation was given space to come out of the formation without carrying fine particles (cement). The analysis was carried out using the finite element method by installing horizontal drain pipe. The result of analysis shows that the horizontal drain installation helps water to come out without creating an overstep layer. The recommended horizontal drain is 8 m long with a slope of at least 3% and a length of 1 m that must enter the sandstone formation as a water source. With this method, the road stability can be maintained and the stabilization can be carried out in an easy, inexpensive, and applicable way.

Rhenium is widely used in manufacturing industry and metallurgy. Today the consumption of rhenium is high, but there are very few deposits in the world where it is mined. Thus, the aim of the study is to identify areas of distribution of rhenium on Kudryavy volcano, located on the islands of the Kuril ridge (Russia). In this connection, during the field period, we took samples of a volcanic massif weighing 70 kg, and also studied the geothermal fields with a pyrometer. Laboratory research included the study of composition of samples by the method of inductively coupled plasma mass spectrometry and spectrometric analysis. The article defines the zones of distribution of rhenium mineralization, presents the results of measurements of the temperature of geothermal fields and the elemental composition of technological samples. The geology, development technology is described, the analysis of the destruction of rocks, determined by the acoustic method, the specific resistance of breakdown during electrothermal loosening is given. The parameters of the tubular shovel conveyor at which the productivity of 88 m3/h is achieved. The results obtained will make it possible to identify promising geothermal fields, determine the development technology, and contribute to the study of volcanic deposits.

This paper considers the implementation of hydraulic fracturing in an oil field located in the Arkhangelsk region in Russia. During the exploitation, the production rates and injectivity of the injection wells in the field were intensively decreased. To increase well flow rates, hydraulic fracturing of the formation was carried out, and the evaluation of the efficiency was performed. Oil production rates after the fracturing increased 3.2 times and the productivity index increased twice. The influence of the geometrical sizes of fractures on the volume of injected proppant was investigated. An increase in the mass of the injected proppant from 2 to 3 tons per 1 meter of formation thickness leads to an average increase in the crack width by 0.5 mm, and the half-length by 40 m. Well work parameters after hydraulic fracturing of a reservoir were obtained as a function of the original parameters of the reservoir. It was observed that there is a sharp decrease in well production rates after fracturing in wells with low bottom hole pressures. When the pressure at the bottom of the well decreases from 60 to 20 MPa, it leads to an average decrease in the crack width by 2 mm, and the half-length of the crack by 50 m.  Direct correlation between the well productivity coefficients after fracturing and the values of bottom hole pressures was observed. The optimal conditions for fracturing were identified, which made it possible to significantly increase the efficiency of the operation.