International Journal of Engineering
Volume:33 Issue: 9, Sep 2020

Herein, fast Fourier transformation square-wave voltammetry (FFT-SWV) as a novel electrochemical determination technique was used to investigate the electrochemical behavior and determination of Riboflavin at the surface of a nanocomposite modified carbon paste electrode. The carbon paste electrode was modified by nanocomposite containing Samarium oxide (Sm2O3)/reduced graphene oxide (RGO) (2:1) to improve detection sensitivity of Riboflavin under optimal experimental conditions. Furthermore, the signal-to-noise ratio was significantly increased by application of discrete fast Fourier transformation analysis, background subtraction and two-dimensional integration of the electrode response over the selected potential range and the time window. Obtained cyclic voltammograms demonstrated a diffusion-controlled reversible electron transfer reaction for Riboflavin in phosphate buffer solution (pH=7.2). The peak potential values were pH-dependent, involving the same numbers of protons and electrons. To obtain the maximum sensitivity, some effective parameters such as scan rate (10 mV/s), accumulation time (0.2 s) and potential (+400 mV), frequency (1420 Hz) and amplitude (20 mV) were optimized. As a result, determination of Riboflavin using FFT-SWV showed a linear range of response from 10 to 400 nM (R2=0.9993), with limit of detection of 0.86 nM. An acceptable recovery percent was also obtained for Riboflavin in human plasma samples as criteria of measurement applicability of the proposed modified electrode.

Increasing the population, urbanization has led to the rapid construction of buildings. Due to space constraints and an increase in land cost, these buildings are built too close to each other and can cause damage under dynamic actions such as earthquakes. A new technique, known as Structural coupling, has been developed recently, has found very effective in dissipating the dispersive vibrations. In this technique, two adjacent dissimilar buildings are connected through a coupling device, such that it can reduce the dynamic response of the structure. The application of the structural coupling technique becomes challenging for similar buildings due to their in-phase behavior under dynamic loads. In the current research, the seismic performance of similar buildings with the coupling technique is experimentally tested on a shake table. A three storey model has been simulated using a unidirectional shake table with the scaled ground motion. Similar building construction uncertainties are accounted for in the study with slight variations in their dynamic properties. The connection devices used are bracings and passive viscoelastic dampers. The results obtained confirm the effectiveness of structural coupling technique with various configurations of dampers for similar buildings over seismic protection individual buildings.

This study explored the effect of porosity and installation angle, thickness (dimension) and second layer of permeable obstacles on density current control and trapping in the laboratory. For this purpose, an insoluble suspended polymer and two types of groove and cavity obstacles made from plexiglass sheets were selected. The experiments were conducted with two different concentrations, five different porosities, four different angles, four different thicknesses and two obstacle layers. The results showed that the optimum porosities for cavity and groove obstacles were 22 and 19%, respectively. In all experiments, the cavity trapping rates of 0.13% and 0.14% at 10% and 20% concentrations were higher than those of groove trapping. In addition, by increasing the angle, the rate of trapping decreased and its value was observed in the groove with the correlation coefficients of 0.995 and 0.981 compared to the cavity. The major effect of obstacles was found to be the flow deceleration where the average velocity in the cavity was obtained 3.62% higher than that in the groove. For the increased thickness with 10% porosity and groove type, the passage of materials from the obstacle further increased. By creating the second layer of obstacle, the passage of materials from the obstacle in the both groove and cavity increased, and the optimal distance of the second obstacle was 2.25 m from the first one.

In this study, the seismic interaction of surface foundations and underground cavities was investigated. For this purpose, a parametric study of geometric dimensions of the foundation and cavity, their location, and the effect of the interaction between surface foundations and underground cavities was evaluated. The variable parameters include the ratio of the overburden height to the foundation width (H/B = 0.5, 1 and 2), the location ratio of the cavity to the foundation width (X/B=0, 2 and 8) and the ratio of the cavity diameter to the foundation width (d/B=0.5, 1 and 2), respectively. The accuracy of the finite element method was evaluated using a laboratory study and it was found that the used method provides an accurate prediction of tunnel behavior.The results indicated that by increasing the overburden height, the stress on the tunnel surfaces was increased for all values of X/B (the horizontal tunnel distance to the foundation width). Therfore, in the case where the tunnel is located exactly along the center at the bottom of the foundation (X/B=0, d/B=2), the maximum stress generated is approximately 2.13 times greater than its corresponding value in the ratio of the depth to width of 0.5 (X/B=0, d/B=0.5). It can be concluded that the higher overburden height, the greater stresses caused by the dynamic loads of the earthquake on the tunnel wall.

Methods to improve bearing capacity of footing resting of collapsing soil can, in fact, take two approaches, improving soil strength properties and intrusion of reinforcing sorces into soil. The footing is modeled by a square steel plate 0.1 by 0.1 m. The footing is loaded as to have a stress of 40 kPa and settlement is receded in dry and in soaking conditions. Two depths of the geo-mesh reinforcement are used, one B (B is width of footing) and 0.5B. For one B depth, three different square sizes of geo-mesh are used, 4B, 6B, and 8B. For the reinforcement depth of 0.5B the three sizes of the geo-mesh used are, 3.5B, 5.5B, and, 7.5B. Results reveal that the best improvement obtained is the case of square geo-mesh width of 7.5B and located at depth of B/2 under footing, with an improvement in terms of collapse settlement of 35%, and a settlement reduction in dry condition of 50%. The least improvement is the case of square geo-mesh with width of 4B and depth of one B, and it was really negligible, about 4% decrease in collapse settlement. Other cases varied between the two mentioned ratios. For findings of study, author recommends not to use geomesh size less than size of footing and not to place it in a depth more than half footing width. As such, in a whole, the effectiveness of geomesh in reducing the settlement of collapsing soil is obvious if used in proper way.

Investigation of the effect of using nanomaterials for improving and Stabilizing the gypseous soil was carried out using laboratory works. The gypseous soils were collected from a site of intake in Bahar Al-Najaf and mixed with two types of nanomaterials (Nano-silica and, Nano-clay) where the nanomaterials were added in small amounts as a percent of the dry weight of the soil sample. Tests to determine the sieve analysis, specific gravity, and collapse potential were performed.  The results of the experimental work showed significant modification in the geotechnical properties of the soil sample. The collapse potential decreases as soon as the used nanomaterials were increased until they reach a percentage after which the collapse potential will be increased. Thus, addition of nanomaterials, even at a low percentage, could improve the properties of gypseous soil. When adding the nano-silica to the soil, the collapse potential (CP) is decreased whenever the nano-silica increases until 1% of the added nanomaterials and then further stabilizer increases the (CP), the percent of decrease in CP is about 91% where the effect of the additive (nano-silica) changes the classification of severity of collapse from “moderate trouble” case to “no problem” case.

This paper presents a novel approach to automatic classifying and identifying of tree leaves using image segmentation fusion. With the development of mobile devices and remote access, automatic plant identification in images taken in natural scenes has received much attention. Image segmentation plays a key role in most plant identification methods, especially in complex background images. Where there are no presumptions about leaf and background, segmentation of leaves in images with complex background is very difficult. In addition, each image has special conditions, so parameters of the algorithm must be set for each image. In this paper, image segmentation fusion is used to overcome this problem. A fast method based on maximum mutual information is used to fuse the results of leaf segmentation algorithms with different parameters. Applying Tsallis entropy and g-calculus, generalized mutual information equations are derived and used to obtain the best consensus segmentation. To evaluate the proposed methods, a dataset with tree leaf images in natural scenes and complex backgrounds is used. These images were taken from Pl@ntLeaves dataset and modified so that they do not have a presumption. The experimental results show the use of Tsallis entropy and g-calculus in image segmentation fusion, improves plant species identification.

A bi-objective mathematical model is developed to simultaneously consider the quay crane and yard truck scheduling problems at container terminals. Main real-world assumptions, such as quay cranes with non-crossing constraints, quay cranes’ safety margins and precedence constraints are considered in this model. This integrated approach leads to better efficiency and productivity at container terminals. Based on numerical experiments, the proposed mathematical model is effective for solving small-sized instances. Two versions of the simulated annealing algorithm are developed to heuristically solve the large-sized instances. Considering the allocation of trucks as a grouping problem, a grouping version of the simulated annealing algorithm is proposed. Effectiveness of the presented algorithms is compared to the optimal results of the mathematical model on small-sized problems. Moreover, the performances of the proposed algorithms on large-sized instances are compared with each other and the numerical results revealed that the grouping version of simulated annealing algorithm outperformed simulated annealing algorithm. Based on numerical investigations, there is a trade-off between the tasks’ completion time and the cost of utilizing more trucks. Moreover increasing the number of YTs leads to better outcomes than increasing the number of QCs. Besides two-cycle strategy and using dynamic assignment of yard truck to quay cranes leads to faster loading and unloading procedure.

In this paper, Cu-Ti nanocomposite synthesized via ball milling of copper-titanium powders in 1, 3, and 6 of weight percentage compounds. The vial speed was 350 rpm and ball to powder weight ratio kept at 15:1 under Argon atmosphere, and the time of milling was 90 h. Obtained powders were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), and dynamic light scattering (DLS). Crystallite size, lattice strain, and lattice constant were calculated by Rietveld refinement with Maud software. The results show a decrease in the crystallite size, and an increase in the internal strain and lattice parameter. Furthermore, the lattice parameter grew by increasing the percentage of titanium. Then, the powders compressed by the cold press and annealed at 650˚C, and finally, their micro-hardness and electrical resistance were measured. These analyses show that via increasing the proportion of titanium, Cu-6wt%Ti with 312 Vickers had the highest micro-hardness; due to the increasing the work hardening. Moreover, the results of the electrical resistance illustrate through increasing the amount of alloying material, the electrical resistance grew which the highest electrical conductivity was Cu-1wt%Ti with 0.36 Ω.

The purpose of present research was production ofZr-based alloy as the nuclear fuel cladding by mechanical alloying (MA) and sintering process. Firstly, Zr and Cr powders were mechanically alloyed to produce the refractory and hard Zr-10 wt% Cr alloy, and then, the powder mixtures were consolidated by press and following sintering at temperature of 800˚C min. The phase evolution, microstructural changes, microhardness, and density of the Zr-10 wt% Cr alloy were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), microhardness measurement, and the Archimedes method. The results showed that the MA increased the solid solubility of the immiscible powders of Cr and Zr; therefore, the Cr atoms were completely dissolved in the Zr lattice after 24 h of the milling time and the nanostructured Zr(Cr) solid solution was obtained with the high microhardness value of about 491 Hv. Also, the results of the density measurement indicated that the resulted density was close to 98% of the theoretical density.

Effect of temperature on formability of AA6063 aluminum tubes in incremental forming process was investigated. Experiments are performed on AA6063 aluminum tubes. A spirally moving tool incrementally expands the tube wall. The tube is clamped from both ends while the deformation zone is not in contact with the die. A circumferential heating system is used to heat the tube due to the low formability of aluminum alloys at ambient temperature. The effects of process parameters including temperature, radial feed, axial feed and tool linear velocity are investigated in order to obtain the highest formability and surface quality. The results show that with a temperature rise from 100°C to 300°C, the expansion ratio increases from 28% to 34%. Axial feeding and temperature are the most effective parameters on the surface roughness and bulge diameter, respectively.

The main purpose of this paper is to assess the impact of the geometry and size of the aggregate, as well as the drying temperature on the compressive strength of the ordinary concrete. To this end, two aggregates with sharp and round corners were prepared in three different aggregate sizes. After preparing concrete samples, the drying operations were carried out in the vicinity of room temperature, cold wind, and hot wind. Next, the linear relationship between the concrete strength and the studied parameters was estimated using Multiple Linear Regression (MLR) method. Finally, the Taguchi Sensitivity Analysis (TSA) and Decision Tree Analysis (DTA) were applied in order to determine the importance of the parameters on the compressive strength of concrete. As a result, it is obtained that the aggregate size has the greatest influence on the compressive strength of the ordinary concrete followed by drying temperature as stated by method TSA and DTA. In addition, the influence percentages reported for each parameter by Taguchi approach and decision tree method are matched. The prediction of the strength obtained by Taguchi method and second-order regression with the experimental data are in a good agreement. It was concluded that the impact of drying temperature on the concrete strength is several times greater than the effect of the aggregate geometry. Finally, the main conclusion of this research is related to the application of cold wind for drying operation, which leads to an increase of the compressive strength by 8.67% and 11.55% for ordinary concrete containing a constant aggregate size of 20 and aggregate geometries of round and sharp corners, respectively.

Co-Continuous Ceramic Composites, referred to as C4, have bi-continuous, interconnected and interpenetrating phases of a metal and ceramic. This bestows such composites with a higher strength to weight ratio compared with traditional composites. In this research work, a C4 composite of AA5083/SiC is fabricated for personal body armour, using gravity infiltration technique. A numerical simulation model of the C4 specimen is developed. This finite element model is utilized to simulate the DoP of a subsonic bullet into the C4 and is estimated as 1.47 mm. The C4 specimen is then, subjected to ballistic tests. A medium velocity projectile with a rated velocity of 326 m/s is used to impact the C4 specimen. The ballistic tests validate the numerical simulation with a DoP of 1.5 mm. Visual inspection reveals brittle cracks and interfacial debonding in the impacted C4. The results indicate that, such composites can potentially be utilized as low cost body armour.

This paper focuses on parameter identification of a target tracker robot possessing flexible joints using particle swarm optimization (PSO) algorithm. Since, belt and pulley mechanisms are known as flexible joints in robotic systems, their elastic behavior affecting a tracker robot is investigated in this work. First, dynamic equations governing the robot behavior are extracted taking into account the effects of considered flexible joints. Thus, a flexible joint is modeled by a non-linear spring and damper system connecting the motor to the link. It is found that the governing dynamic equations include some unknown parameters, which must be identified in order to design the robot system. Consequently, a PSO-based identification scheme is proposed to achieve the unknown variables based on the experimental data of the open-loop system. Lastly, for validating the proposed identification scheme, the obtained results are compared to the experimental measurements as well as the results of another similar work in which the robot is modeled with rigid joints. The consequences reveal that the mathematical model of the robot with flexible joint can describe the elastic behavior of the tracker robot. Thus, a better agreement between the simulation and experimental data are found in comparison with outcomes of the robot model with rigid joints.

Thermoplastic elastomer of PA6/NBR reinforced by various nanoparticles have wide application in many industries. The properties of these materials depend on PA6, NBR, and nanoparticle amount and characteristics. In this study, the simultaneous effect of NBR and graphene nanoparticle content on mechanical, thermal properties, and morphology of PA6/NBR/Graphene nanocomposites investigated by Central Composite Design (CCD). Thermal properties and morphology of PA6/NBR/Graphene nanocomposites were investigated by Differential Scanning Calorimetry (DSC), X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM). The results indicate that a small percentage of error between predicted values of mechanical properties and experimental values was achieved. An increase in graphene content have a positive impact on the tensile strength but increasing the NBR phase has the opposite effect. A maximum tensile strength of 35.3 MPa for PA6/NBR/Graphene nanocomposites was obtained at the NBR and graphene content of 20 %wt and 1.5 %wt, respectively. The thermal behavior of the PA6/NBR blend improved with addition graphene. With the addition of 1.5 % graphene content to PA6/NBR blend, the crystallization temperature and melting temperature increased from 192.1 to 196.2 °C and 221.1 to 223.4 °C, respectively.

In this experimental work, AISI 304 was welded via metal inert gas (MIG) welding process with Argon (Ar) as shielding gas. In the present study, AISI 304 was subjected to different heat input using a standard 308L electrode. Weld quality i.e. ultimate tensile strength, toughness, microhardness, and microstructure of AISI 304 were examined. Microstructures of welded joints were studied using scanning electron microscopy (SEM), linked to the SEM was used to determine the chemical composition of phases formed at the joint interface and from the result, it was revealed that at low heat input ultimate tensile strength is higher than those at medium and low heat input. From the result, it was also observed that grain coarsening extent in the HAZ increases with an increase in the heat input. It was also found that the fractures of toughness samples were brittle in nature which shows the low ductility and brittle fracture. Weld zone microstructure exhibited skeletal δ-ferrite in austenite matrix with various ferrite contents. Microhardness of weld bead was found to decrease with increases in the heat input. It was also observed that at medium heat input there was an improvement in tensile strength, elongation, and hardness due to finer grain structure and smaller inter-dendritic spacing.