International Journal of Engineering
Volume:34 Issue: 2, Feb 2021

A  high-performance adsorbent  was produced by grafting  polyaniline onto biopolymer chitosan.  The morphological  structure  of  cross-linked  chitosan  grafted  with  polyaniline  was  studied  by  scanning electron  microscopy.  Functional  groups  of  the  synthesized  adsorbent  were  identified  by  Fourier- transform  infrared.  The  performance  of  the  prepared  adsorbent  was  examined  by  batch adsorption experiments. The adsorption studies were performed with different operating parameters such as contact time,  initial  pH,  adsorbent  dosage  and  temperature.  To  evaluate  adsorption  isotherms,  Freundlich, Langmuir and Dubinin-Radushkevich models were fitted to obtained data and the isotherm parameters were determined. Kinetics of the adsorption was studied by pseudo-first-order and pseudo-second-order models. It was observed that the obtained data were fitted more accurately with the pseudo-second-order model than the pseudo-first-order model. At optimum conditions, the maximum capacity and the removal efficiency  of  copper  ions  adsorption  were  obtained  131.58  mg/g  and  92.5%,  respectively.  The regeneration  efficiency  and  the  removal  efficiency  of  regenerated  adsorbent  were  97.7  and  90.4%, respectively.  The  results  revealed the  adsorbent has a great potential  for  adsorption of Cu  (II)  from aqueous solution

Adhesive joints find numerous applications in various industrial fields. They represent a valid alternative to traditional joining methods. Much of the available scientific literature has focused on the study of adhesive joints subjected to tensile loads. There have also been numerous studies concerning the stresses distributions in the adhesive layer. However, in real case applications, adhesive joints could also be subject to cyclic tensile-compression loads and therefore could be subject to buckling phenomena. The objective  of  the  present  paper  is  to  investigate  the  numerical  study  of  the  stress  distribution  in  the adhesive layer under buckling condition. The study presented develops with the analysis of a single-lap joint  with  a  combination  of  steel  adherends  and  three  different  structural  adhesives  with  different thickness  and  Young’s  modulus.  The  joints  are  modeled  using  FE  ANSYS©19  software.  Through numerical  analyzes,  it  is  possible  to  predict  the  value  of  the  critical  load  for  each  single  analyzed combination. Once the critical load is determined, the stresses in the middle plane of the adhesive layer are determined. The results obtained show that for small adhesive thicknesses (i.e. 0.30 mm) it is possible to reduce the stress peaks - with the same critical load value - by using structural adhesives with low elastic modulus (e.g. silicones).

< p>Gypsum mortar is a common building material that can be used especially for plastering the walls. This mortar has three important weaknesses which can limit the gypsum mortar for building and statue construction. First; it has low compressive strength. Second; it has high water absorption, and third; it has low setting time. In the current study, cement, Nano silica, and a superplasticizer with polycarboxylate ether were used for solving the problems. The results showed that using cement with providing C-S-H can improve the mortar strength trend line. The results showed significant growth of 28th day compressive strength (from 9 MPa to 45 MPa). Using Nano silica increases the compressive strength by making C-S-H dense and decreases the water absorption to 1/3 of the control sample.  Consuming polycarboxylate ether causes the uniform dispersion of Nanoparticles through mortar. This even diffusion blocks the pores and reduces their mean dimensions. The ANOVA test was used to find the main effective parameters on the 28th day compressive strength, water absorption, and setting time. In this regard, Nano silica (49.82% contribution), cement content (56.68% contribution), and superplasticizer (73.10% contribution) have the main roles in compressive strength, water absorption, and setting time, respectively.

This study investigates the bond strength behaviour of plain surface wave type configuration (PSWC) rebars in comparison to mild steel (MS) and high yield strength deformed (HYSD)  rebars of varied rib configuration as per BIS and ASTM standards. The variables in the rebar include plain surface, curved surface, parallel rib, diamond rib and Nano modified cement polymer anticorrosive coating (CPAC). Total of 30 pull-out specimens and 12 beam-end specimens were put to a pull-out test following BIS and ASTM standard respectively. The load corresponding to 0.025mm free end (FE) slip and 0.25mm loaded end (LE) slip were carefully observed. The load-deflection behaviour, appearance of the first crack in the specimens and ultimate failure load was recorded. The experimental results showed that as compared to MS rebars, HYSD rebars offer an approximately threefold increase in ultimate bond strength and 1.5 times increase in usable bond strength irrespective of varied rib configuration. PSWC rebars with 4mm offset and 80mm pitch offered 2.4 times increase in ultimate strength and 76.2% increase in usable bond strength as compared to MS rebars. The ultimate pull-out load of PSWC rebars was around 25% and the usable bond strength was only 8.6% lesser than HYSD rebars with parallel ribs. The adopted coating enhanced the corrosion resistance and the reduction in bond strength with any surface configuration was less than the permissible maximum reduction of 20% as specified in IS 13620-1993. Hence it can be concluded that PSWC rebars offered promising bond strength results and upon further optimization and study in other aspects,  PSWC rebars can be a way to replace HYSD rebars in future for enhancing concrete durability at zero added cost.

When a planned special event (PSE) is mentioned, large and international organizations are considered. These organizations attract so many people all around the world to local points. However, relatively small scale PSEs such as ordinary league games that are organized once every two weeks that impact the daily traffic of the cities especially metropolitans, are neglected. This paper focuses on the travel demand modelling of the ordinary super league games in Istanbul. As a purpose of this paper, in order to obtain a customizable and standalone PSE model, survey design and data collection procedures, a new methodology for trip generation, trip distribution, and modal split steps of the traditional 4-step demand modelling are considered. With the opportunity provided by the newly proposed methodology, unlike most previous studies in literature, all trips and activities in the same day with the PSE are taken into the modelling process. Because of the nature of the PSEs, participants prefer to perform additional (derived) activities in the time between leaving the origin and joining the PSE. Accordingly, 1, 2, and 3-step groups are defined, and the shape of trip length distributions are different not only from the peak hours but also from each other. At the end, the model estimation and development of the PSE travel demand model are presented with conclusions and suggestions.

Losing a house is the biggest threat to people during natural disasters, such as earthquakes that are frequent natural hazards in Indonesia. Post-disaster housing reconstruction becomes a construction challenge to build adequate houses contributing to personal safety, health and comfort. The invention of a simple ergonomic instant house using lightweight steel structure, bracing, and the local wood walls is urgently needed. This invention is proposed to provide quick and low-cost mass construction house which meet safety and comfort requirements. The house is designed in 6 meters by 3.5 meters while the height of the ceiling is 2.8 meters. The house's front side is equipped with a door and a window, while at the back is equipped with a window. The six criteria for appropriate technology are considered in the construction method. The criteria include technical, ergonomic, social and cultural, energy-saving systems, and environmentally friendly. The scheme of systemic, holistic, interdisciplinary and participatory (SHIP) is considered at stages of design, construction and maintenance. The structure system is analyzed with a 3D model of the finite element method using SAP-2000. The given questionnaires' feedback assesses the satisfaction of the residents living in the house. The conclusions are included in five substances: (1) The house materials are lightweight steels, bracings, and local wood; (2) The structure should meet the safety requirement; (3) The house satisfies the requirement of safety and health; (4) The residents are satisfied and positively improve their living conditions following the disaster; (5) The house satisfies a simple ergonomic house.

This study aims to investigate the computational effect of Earth's viscosity on the Coulomb stress changes. Therefore, several large earthquakes in the Alborz region are selected and Coulomb stress changes are calculated in them, then the Coulomb stress temporal changes are shown by assuming the earth as an elastic layer on a viscous- elastic half-space. The spatial and temporal changes of the crustal deformation process associated with earthquakes depend on several parameters including the thickness of the lithosphere, viscosity of the asthenosphere, and dip angle of fault. The findings of this study are presented by determining the impact of modeling results on each of the input parameters through the sensitivity analysis of co-seismic and post-seismic deformation due to the dip-slip and strike-slip faulting. In addition to the useful results reported for the impact of parameters, the obtained results indicate the occurrence of numerous aftershocks in a region with increased Coulomb stress from 0.1 to 0.8 bar and the non-occurrence or low-occurrence of aftershocks in a region with reduced Coulomb stress. In addition to the predicted locations of aftershocks, it is also possible to determine the location of the next major earthquake using Coulomb stress change calculations.

In the last five decades, the rise of the plastic industry led to increase in the waste of plastic in the environment, therefore the scientists were thinking to reduce plastic waste by recycling the plastic. On the other hand, there is a problem of collapse of gypseous collapsible soil upon wetting. In this paper, one of the methods to recycling plastic is adopted to improve the gypseous soil by mixing with 1% plastic fiber to increase the shear strength and improve collapsibility of soil at the state of saturation or soil wetting. The soil used is classified as SW-SM, the gypsum content is 39% and the relative density is equal to 73%.Fiber plastic is made from plastic waste in the environment of investigation. Several tests were conducted on the soil such as collapse test, direct shear test, also model loading test on the soil before and after mixing with fiber plastic. The worst case of gypsum soil is at saturation by rain or groundwater rise which was simulated during the loading test. It was concluded that the value of soil cohesion gradually increases from 2 MPa at the state of the natural soil to 11 MPa after mixing with 1% of plastic fibers. From the three model loading tests, the load carrying capacity of a model footing on submerged gypseous soil increased from 2.66 MPa for untreated soil to 4.8 MPa when the soil is mixed with 1% plastic fiber and extended to a depth of 0.5 B. The earing capacity also increased to 6.8 MPa when the soil is mixed with 1% plastic fiber and extended to a depth of B.

The analysis and design of reinforced concrete slabs supported on 3-sides in masonry or reinforced concrete construction involve analytical formulations. In published analytical formulations, orthotropic coefficients and continuity factors are unknown parameters. To obtain moment carrying capacity of the slabs using available formulations, these factors must be required. In this research work, these orthotropic coefficients and continuity factors are presented for transverse loaded RC rectangular slabs supported on three sides under uniform area loading at top face of the slab. These coefficients were obtained using FEA (Finite element Analysis) based Structural Analysis Program (SAP) software. It is also validated with FEA (Finite element Analysis) based SCIA Engineer software and published formulations. It have been observed that obtained results are well comparable with published literature and FEM based software. Results presented in this research paper are conducive to predict the moment-field of the reinforced concrete rectangular slabs supported on three sides having one edge is unsupported. These coefficients will be very helpful for structural designers dealing with reinforced concrete slabs supported on three sides.

Strength capacity of reinforced concrete columns is very important to resists and transmit the external loadings. For Architects the engineerings requirements to use small cross section of reinforced concrete columns or in case of poor control quality we need to increase the compressive strength of concrete or use a strengthening technique of the structural elements such as column. In the present paper, the behavior and strength of four steel fiber reinforced self-compact concrete columns reinforced by one layer of CFRP that is wrapped around a square of reinforced concrete columns subjected to static loads is investigated. Self-compacting concrete by using limestone powder is adopted and is mixed with different percentages of steel fiber such as 1%, 1.5% and 2%. Different tests are adopted to investigate the mechanical properties of self-compacted concrete mixed with different steel fiber percentages. Test results show that there is an increase in concrete mechanical properties such as compressive strength, splitting tensile strength and modulus of rupture that reflects on the increase in load capacity of column; specimens when wrapped by CFRP. The increment in columns strength capacity is more than 50% as compared with the control column. All the test specimens are modeled using finite element analysis by ANSYS and the numerical results are compared with tested specimens.

Three parameters, size, shape of aggregate, and water to cement ratio, play important role on concrete behavior. To study the effect of these parameters, two types of aggregates were used, rounded (river) and sharped corners (broken). The maximum sizes of aggregates were chosen to be 9.5, 12.5, 19 and 25 mm for water to cement ratio were 0.35, 0.42, 0.54 and 0.76. In this investigation, the total of 32 mixed designs were made. The stress-strain tests were performed on the entire samples, and the results were compared with the Popovics model. To further evaluate the analysis, three criteria, correlation coefficient, variation coefficient, and percentage of change in energy absorption were demonstarted. Analysis showed that there is significant differences between the Popovics model and our experimental results. The Modified Popovics model was introduced for better understanding the concrete behavior in compression. The proposed model covered a wide range of the parameters concerned in this investigation. The Modified Popovics model was comapred with several models such as the Popovics, Hognestad, Thorenfeldt, and Tsai and the results showed that modified approach has a better clarification for behavior of concrete in compression. Moreover, the results indicated that these models were more accurate for prediction of concrete behavior with rounded aggregates in comparison to sharped aggregates.

Today, the importance of using vernier machines in wave energy converters has increased because of its simple structure and ability to generate a lot of thrust force at low speeds due to the magnetic gear effect. The linear vernier permanent magnet machine has been designed in various structures. Proper design and selection of the main parameters of the machine will improve performance and increase the efficiency of the linear vernier machine. One of these parameters is the shape of the permanent magnets and how they are magnetically oriented. The novelty of this paper is the reduction of leakage flux, achieved by changing the shape and orientation of the permanent magnet. Three types of linear permanent magnet vernier machines with different permanent magnet structures and orientation, including V-shape, Halbach array and consequent-pole are presented.  The considered machines have been compared to each other and to the existing machine in terms of airgap flux density, back EMF, PM flux, Inductance, thrust force, detent force, loss, efficiency, power factor, flux density and flux line, using the finite element method in the same conditions and with the same volume of permanent magnets. The results show that the magnetic orientation and shape of the permanent magnet have a considerable effect on the leakage flux, and all the proposed models have a lower leakage flux and better performance compared to the existing model.

This article presents a new method for detecting heterogeneities in wind data set to predict wind speed based on the well-known Hidden Markov Model (HMM). In the proposed method, the HMM categorizes the wind time series into some groups in which each group represents a wind regime. Each regime uses an internal first-order Markov Chain (MC) for forecasting, and the combination of all regimes outputs generates the final wind speed forecast. The model proposed in this study is called “Hierarchical Markov Model ”. The first layer detects and separates wind regimes as heterogenic groups of wind data by the use of wind direction data, based on  HMM, and the second layer forecasts the wind speed using MC. The proposed model is implemented and tested using real data. Its effectiveness in terms of temporal stationary index is compared with that of a first-order MC-based method. The results showed that more than 70% improvement can be achieved in wind speed prediction by the proposed method. Moreover, it gives a probability distribution function of wind speed prediction, which is sharper than the one obtained with the first-order MC; means that more precise prediction

Human action recognition has undoubtedly been under research for a long time. The reason being its vast applications such as visual surveillance, security, video retrieval, human interaction with machine/robot in the entertainment sector, content-based video compression, and many more. Multiple cameras are used to overcome human action recognition challenges such as occlusion and variation in viewpoint. The use of multiple cameras overloads the system with a large amount of data, thus a good recognition rate is achieved with cost (in terms of both computation and data) as the overhead. In this research, we propose a methodology to improve the action recognition rate by using a single camera from multiple camera environments. We applied a modified bag-of-visual-words based action recognition method with the Radial Basis Function-Support Vector Machine (RBF-SVM) as a classifier. Our experiment on a standard and publicly available dataset with multiple cameras shows an improved recognition rate compared to other state-of-the-art methods.

In this paper, an enhanced self-checking carry select adder (CSeA) architecture is introduced. However, we first show that the carry select adder design presented literature does not have the self-checking property in all of its parts in spite of the stated claim. Then, we present a corrected design with the self-checking property that requires more overheads. In addition, we reveal some mistakes in reporting the transistor count of the proposed design in the literature in different sizes, and correct them which again leads to more transistor count and overhead. At the end, due to the fact that the performance of a CSeA depends on its grouping structure, the area overheads of different CSeAs including the corrected designs and the best of previous self-checking designs will be evaluated with respect to the same-size and different-size grouping structures. These evaluations show the comparison of different CSeAs, more appropriate compared to the previous evaluations.

Nowadays, due to the availability of low-cost and high-resolution digital cameras, and the rapid growth of user-friendly and advanced digital image processing tools, challenges for ensuring authenticity of digital images have been raised. Therefore, development of reliable image authenticity verification techniques has high importance in digital life. In this paper, we proposed a blind image splicing detection method based on color distribution in the neighborhood of edge pixels. First, we extracted edge pixels using contourlet transform. Then, to accurately distinguish the authentic edges from tampered ones, Interquartile Range (IQR) criteria are utilized to illustrate the distribution of Cr and Cr histograms of the spliced boundaries in YCbCr color space. Finally, a segmentation method is used to improve the localization performance and to reduce especially the computational time. The effectiveness of the method has been demonstrated by our experimental results obtained using the Columbia Image Splicing Detection Evaluation (CISED) dataset in terms of specificity and accuracy. It is observed that the proposed method outperforms some state-of-the-art methods. The detection accuracy is approximately 97 with 100% specificity.

In this paper, a new feature extraction method is presented based on spectro-temporal representation of speech signal for phoneme classification. In the proposed method, an artificial neural network approach is used to cluster spectro-temporal domain. Self-organizing map artificial neural network (SOM) was applied to clustering of features space. Scale, rate and frequency were used as spatial information of each point and the magnitude component was used as similarity attribute in clustering algorithm. Three mechanisms were considered to select attributes in spectro-temporal features space. Spatial information of clusters, the magnitude component of samples in spectro-temporal domain and the average of the amplitude components of each cluster points were considered as secondary features. The proposed features vectors were used for phonemes classification. The results demonstrate that a significant improvement is obtained in classification rate of different sets of phonemes in comparison to previous clustering-based methods. The obtained results of new features indicate the system error is compensated in all vowels and consonants subsets in compare to weighted K-means clustering.

Accurate segmentation of lesions from dermoscopic images is very important for timely diagnosis and treatment of skin cancers. Due to the variety of shapes, sizes, colors, and locations of lesions in dermoscopic images, automatic segmentation of skin lesions remains a challenge. In this study, a two-stage method for the segmentation of skin lesions based on deep learning is presented. In the first stage, convolutional neural networks (CNNs) estimate the approximate size and location of the lesion. A sub-image around the estimated bounding box is cropped from the original image. The sub-image is resized to an image of a predefined size. In order to segment the exact area of the lesion from the normal image, other CNNs are used in the DeepLab structure. The accuracy of the normalization stage has a significant impact on the final performance. In order to increase the normalization accuracy, a combination of four networks in the structure of Yolov3 is used. Two approaches are proposed to combine Yolov3 structures. The segmentation results of two networks in the DeepLab v3+ structure are also combined to improve the performance of the second stage. Another challenge is the small number of training images. To overcome this problem, the data augmentation is used, as well as using different modes of an image in each stage. In order to evaluate the proposed method, experiments are performed on the well-known ISBI 2017 dataset. Experimental results show that the proposed lesion segmentation method outperforms the state-of-the-art methods.

The purpose of this paper is to design a green Blood Supply Chain (BSC) network regarding expiration date and backup facilities. The proposed model is a bi-objective Mixed Integer Programming (MIP) one. The two objective functions are to minimize the total cost and the detrimental environmental impacts of shipping between facilities and generated wastes in the network. A Goal Programming (GP) approach is used to convert the multi-objective model into a single one. Moreover, to meet the demand, blood groups and plasma expiration date are also investigated. Since it has been proven that plasma of the people who have fully recovered from COVID-19, can help other patients to recover from this insidious disease; therefore, the proposed BSC network can supply the needs of this particular category of patients as well. To examine the feasibility of the proposed model, some random examples with different dimensions are generated and solved using the CPLEX solver of GAMS software. Furthermore, a real-case problem in Esfahan (Iran) was investigated to illustrate the applicability of the proposed model, and the sensitivity analysis was performed as well. Results approved the applicability of the proposed model in a real situation.

The present investigation aims to deposit the three different hard facing powder (Triboloy T-700 and PAC 718, and TETCO 41 C) on SS 304L using laser cladding technique. The single and overlapped clad track was deposited using 2 kW laser power system. The optimized laser process parameters and 50% overlap clad track was used to deposit a large surface area. The optimum laser process parameters were finalised using single clad structure study.  The cross-sections of the clad layers were used to obtain the microstructure and micro-hardness from different regions namely, clad layer, diffusion layer, and substrate. Throughout the study, the laser power was kept constant i.e. 1.2 kW. For single clad deposition, the scanning speed and powder feed rate varied from 0.3 to 0.5 m/min and 4 to 9 g/min, respectively. T-700 and PAC 718 shows uniform developing micro-structure while METCO 41 C shows the development of mixed dendritic and cellular type microstructure. The Triboloy shows the maximum surface hardness of 534 Hv, 321 Hv for PAC 718, and 294 Hv for METCO 41 C.

This article is devoted to the photovoltaic system simulation. Photovoltaic systems operate in different conditions such as changing solar irradiance and environmental temperature. Analysis of the existing methods for photovoltaic system simulation was carried out in this paper. The formal model of the electricity consumption system was developed, which included the photovoltaic system and the electrical storage system. The expediency of using simulation modeling tools in the design of solar panel optimization tools was shown by application of maximum power point tracking methods. The developed software provides the ability to build current-voltage and high-voltage characteristics of solar cells at different values of the intensity of solar radiation and temperature.. The voltage and load current differ up to 50% from the voltage and current of the operating point of the solar panel, which is set to the optimal value using maximum power point tracker. The architecture of the software extends the capabilities of simulation modeling of systems based on solar panels. The optimizer model block along with the implementation of the maximum power point tracking algorithm can be further refined by using more sophisticated algorithms. The developments are innovative and their practical implementation will have a significant impact on the energy security of countries

This study was a preliminary study on flame spray coating with hydroxyapatite (HAp). Coating is one of the technique to improve metal resistance to corrosion. In this study, flame spray coating using HAp was performed on stainless steel 316 L as a material for medical devices. This synthetic compound contains elements which are biocompatible and bioactive in human body where they can stick to body tissues or muscles.HAp has been extensively used as a bone substitute because of its crystal structure, biocompatibility and osteoconductive nature. In this study, 316L SS was coated by HAp using flame spray method with varied oxygen flowrate and air pressure. The result of this study showed that the air pressure of 1 bar and oxygen flowrate of 25 l/min had the thickest coating which was 123.5μm and the lowest corrosion rate which was 0.0261 mm/year. The air pressureof 3 bar and oxygen flowrate of 35 l/min produced the lowest thickness which was 32.5μm and the highest corrosion rate which was 0.0761 mm/year. The use of high air pressure and oxygen flowrate decreased the coating thickness and the corrosion rate. The result revealed that flame spray method was effective to be used to coat HAp on 316L SS.

The main purpose of this study is to prepare the nanocomposite samples with synergistic properties containing the mechanical, thermal and antibacterial properties. For this purpose, the combination of cellulose nanofiber (CNF) and Ag (silver) nanoparticles were incorporated into polylactic acid (PLA) matrix by solution casting method. The CNF in constant content of 1 wt.% and Ag nanoparticles in the content of 1, 3, and 5 wt.% were incorporated into the PLA matrix. The structure and morphology of the nanocomposite samples was characterized by FE-SEM, and mechanical, antibacterial, and thermal properties of the nanocomposites were evaluated by tensile, agar disk-diffusion, and DSC tests, respectively. FE-SEM images showed the uniform dispersion of the nanoparticles within the polymer matrix. The simultaneous addition of two nanoparticles significantly raised the mechanical properties such as tensile strength and tensile modulus by 40% and 9%, respectively. However, CNF had no considerable effect on the thermal and antibacterial properties of the PLA matrix. Unlike CNF, Ag nanoparticles significantly improved the antibacterial properties of the nanocomposites against staphylococcus aureus and Escherichia coli bacteria, and enhanced the thermal stability of the PLA matrix. Ag nanoparticles improved the degree of crystallinity of PLA from 10.5% to 17.9%, and Tm from 147.8 to 153.6 °C. By incorporating 5wt.% Ag nanoparticles, the inhibition duameter increased from 20 mm to 39 mm for staphylococcus aureus.

Rare earth compounds widely used in industrial applications and new processes with green solvents are appropriate for recovering these elements. In this study, the ionic liquid application development was investigated to extract europium ions in single and binary systems. A green procedure for europium (III) extraction from aqueous chloride solution was investigated using phosphonium ionic liquid Cyphos IL 104. Comparative conditions were investigated for analyzing better results with the presence of organic extractant such as Cyanex272, D2EHPA in the batch experiments. The experiment design was carried out based on the central composite design principles to analyze the relationships between the responses and the significant parameters. The obtained data revealed that the quadratic equation has good desirability to predict the extraction percentage. Investigation of the extraction process showed that the ionic liquid Cyphos IL104 has selective power in the extraction of europium and the efficiency is higher than the organophosphorus extractants. Accordingly, optimum conditions for maximum removal of europium ions were obtained equal to 5.5, 1, 16 min, and 0.008 M for feed acidity (pH), phase ratio, time, Cyphos IL 104 concentration. Examination of binary systems of rare earth elements showed that ionic liquid had positive and negative effects on the separation factor. The high efficiency of ionic liquid in the reuse condition indicated that the system is appropriate from an economic perspective.

This research mainly focuses on the effects of heat absorption/generation and radiation on the hydromagnetic flow of Fe3O4-ethylene glycol nanofluid through a shrinking wall with porous medium and the computation of the entropy generation. We considered basic governing ordinary differential equations into partial differential equations by using appropriate similarity solutions. Moreover, hyper geometric function is employing to determine the formulated problem.  We analyze the effects of appropriate physical parameters on the Bejan number, Entropy generation, Nussult number, skin friction, fluid temperature and velocity profiles. In addition, the derived result of the present study is compared with those in the existing literature. We noted that the presence of heat absorption and suction parameters reduces the Bejan number and increases the entropy generation, and the heat source, porous medium, radiation parameters minimize the entropy production.  The presence of porosity parameter reduced the fluid velocity, improved fluid temperature and minimized the entopy production. Nanosolid volume fraction parameter reduced both Nussult number and skin friction coefficient.

One of the most prevalent machining processes in medical treatments is bone drilling process. During bone drilling, excessive process force can cause breakage, crack initiation and severe damage to bone tissue. In this paper, a systematic study with simultaneous use of response surface method, sensitivity analysis based on Sobol method and regression analysis is performed for investigation the effect of helix angle and point angle of the tool as the most important geometrical parameters on imposed force to the bone during drilling process. Initially, using design of experiments and response surface method, imposed force to the bone is modeled and the governing second order linear regression equation is derived and verified. Then, using Sobol sensitivity analysis, with ability to quantify the sensitivity, it is attempted to investigate the effect of input parameters on drilling force. Finally, optimization of the process inputs is followed to find the best combination which yields the desired drilling force. The minimum drilling force, within the range of input parameters, coincides with point angle of 90 and helix angle of 18. This minimal force is lower than the force in surgery and standard tools. The results showed that an increasing in point angle leads to an increase in drilling force. Also, it is concluded that there is an optimum value for using the helix angle in bone drilling process with minimum imposed force.

Taking road roughness, aerodynamics, and weather conditions, viz temperature and humidity, into consideration, the force applied to the wheel of a half-vehicle model traveling at constant speed has been calculated. A D-type rough horizontal road according to ISO 8606 evaluations was chosen for the experiment and the surface profile of which was measured by means of a topographic camera of Leica series to acquire discrete data to model the road roughness. The data have been converted from discrete points into smooth continuous linear functions with quadratic blends, because of the fact that the governing differential equations of motion of the vehicle model require the road roughness and the time rate of change thereof. The line of action of wind or aero-dynamical force applied to the vehicle model has been assumed to pass through the vehicle mass center. The vibrations of the half-vehicle model have been found via the Runge-Kutta method. DoE (Design of Experiments) has been used to investigate the effects of air temperature and humidity on the front and rear wheels. It was found that the value of force applied to the front wheel is far greater than that applied to the rear wheel (about 16.5%). Also, the role of the air temperature is much more effective on the wheel force than the air humidity. Moreover, the force of the front wheel is directly related to the values of weather parameters and the force of the rear wheel is inversely related to it.

Studies have shown that most of the particles sprayed on emergency respirational patients, accumulate inside the endotracheal tube and its connector. In this paper, applying Computational Fluid Dynamics (CFD) and Response Surface Method (RSM), an optimized geometry is introduced for higher efficiency of the drug delivery for patients with emergency respiratory diseases. In CFD modeling, finite volume method and for two-phase flow modeling, Lagrangian method is used. Reynolds averaged Navier–Stokes equations with Reynolds stress turbulence model are solved using SIMPLE pressure correction algorithm within the computational domain. The velocity fluctuations are simulated using the Discrete Random Walk (DRW). For optimization process, six different parameters including three dimensions of the connector of the tube: connector length, connector diameter and injection diameter, injection velocity of the drug particles, air flow velocity and particle size are investigated. Using Design of Experiments (DOE) and RSM, the output efficiency of the model and second-order regression equation model are derived and accuracy of the model is confirmed. Then the effect of each input parameter on the efficiency is investigated. Dringer algorithm is applied to optimize the process and the best combination of input parameters yielding the highest efficiency is introduced.

Metal matrix composite (MMC) gears are used as a major component in the industry and are responsible for providing high-quality power transfer at high speeds. High quality, including high strength and impact-resistance, low brittleness, and long lifetime, is very important and needed in the industry. Gears are made of different materials, and, nowadays, researchers and industrialists have turned to designing, manufacturing, and using composite gears more than other gears due to their low weight, high hardness and strength, and better mechanical properties. In this research, the stress and strain behaviors are predicted in the composite gears made of aluminum silicon carbide with 3 different SIC volume fractions, namely 55 vol.%, 40 vol.%, and 30 vol.%, and with specifications of (Al45/SIC55, Al60/SIC40, and Al70/SIC30) and gears made of aluminum oxide with 3 different alumina weight fractions, namely 94 wt.%, 96 wt.%, and 99.5 wt.% to evaluate and compare the stress behavior due to different forces exerted on a single gear tooth in MMC gears. The Al45/SIC55 composite experienced the largest stress compared to other composites such as Al60/SIC40 and Al70/SIC30. The strain values (unlike the stress values) reduced with increasing in the volume fraction of the SIC reinforcement. Moreover, 94% aluminum oxide composite showed larger stress compared to 96% aluminum oxide and 99.5% aluminum oxide. The spur gear is designed and analyzed using SOLID WORKS and ANSYS Workbench softwares.

Tungsten inert gas (TIG) welding process is one of the complex production methods. The reason is the drastic changes in the metallurgical structure of welding parts due to the heating and cooling cycle during welding. These changes cause various metallurgical and mechanical defects of the parts and weaken the mechanical properties of the parts. Many parameters in welding have different effects on the quality of welding parts. To create a suitable weld, it is necessary to identify the effect of these parameters and to be able to estimate it and select the appropriate and optimal conditions. Accordingly, In this study, an experimental investigation were conducted on determining the mechanical characteristics of the pieces through variation of three main welding parameters including advance speed, welding amperage and preheating temperature.  Due to the difficulty of changing the rate of advance speed in manual welding, a robotic welding arm was designed for welding 316 stainless steel in the current paper, in which a microcontroller tuned the speed and welding length. By collecting the practical data, the effect of the input data (advance speed, welding amperage and preheating temperature) investigated in durability and strength of the joints. In other words, the tension and durability of the joints for stainless steels are proposed for various welding parameters to enhance the optimal conditions based on the experimental results. In samples with low advance speed, in addition to increase the solidification time, the coarseness of the structure and the burning of the edges of the welded parts due to the low speed and high amps, reduce the tensile strength. Also, the results showed that by increasing the amperage, the strength of welding parts decreases due to the burn defect of the plate edges, which can be minimized by increasing the welding speed and reducing the effect of extreme heat on the edges. Finally, by analyzing the effect of the input parameter on the output, the best conditions of the adjustment parameters in butt-welding were acquired among existed samples for welding 316 stainless steel.

Quantitative calculation of structural safety using its specific limit-states is of great importance. Due to the stochastic properties of strength, loading, and environmental reduction functions, these parameters cannot be considered as deterministic variables. In this paper, a probabilistic model including the stochastic properties of the strength reduction factor was proposed to calculate the time-dependent reliability of concrete structures. In this model, the statistical properties of applied loads were also considered. The strength reduction model was calculated quantitatively using the statistical properties of the reducing agent. In this research, the major factor contributing to the strength reduction is the reduction in the cross‐section of the steel bars, reduction of bonding strength, and the spalling of the concrete cover due to reinforcement corrosion induced by chloride ingress. The results of this model were compared to the calculation of reliability using the direct implementation of strength values and another simplified method that only considers initial strength as a random variable. In the methods under investigation, the effect of the uncertainty of reducing factor on the mean and coefficient of variation of results was also studied. The results showed that the probability of failure increases between 25% to 50%  when the uncertainty of the reducing factor is taken into account. The proposed model has more realistic results than the simplified model, and these results could be improved for achieving more exact outcomes with lower uncertainty.

Cement has been used for decades in the industry to serve various important functions inside oil and gas wells. Due to the complications and variations in the geological and technical conditions of a well, various cement compositions are designed and utilized in different world regions. Many hydrocarbon reservoirs are covered by thick salt formations, which are considered problematic and costly to be drilled and cemented. Cement slurry, as a water based solution, interacts with salt rock, as a result of which cement properties are changed that consequently may jeopardize well integrity across salt formations and successful exploitation of beneath hydrocarbon reservoirs. In this study, based on experimental and industrial experiences, a cement composition is developed that meet the requirements of cementation in salt layers. Experimental investigations are conducted on the bonding strength at the salt-cement interface, as the bonding strength is considered as one of the factors that significantly affect overall cement efficiency in providing well integrity. Results confirm the effectiveness of the developed composition for cementation of salt layers.