International Journal of Engineering
Volume:32 Issue: 1, Jan 2019

Microalgae Chlorella Vulgaris is enriched in vitamin B12 and cobalt ion which is positioned in the center of the vitamin molecule. This study aimed to investigate how different concentrations of cobalt chloride salt affected the vitamin B12 production by utilizing CO2 gas, to assess C. vulgaris biomass. Therefore, Bold’s basal medium used as the medium and 0.5, 1.5, 2 and 2.5 μM cobalt chloride salt was added to C. vulgaris culture. Under four cobalt chloride salt treatments, the best growth rate was obtained at the 2 μM of cobalt chloride salt (0.186 + 0.07 g /L.d). CO2 gas was supplied by 5% CO2 gas cylinder and fermented milk as a novel biological CO2 gas generator (CO2,10%). Use of fermented milk is a practical approach for elimination of waste gas emission and converting CO2 into biomass. The results revealed that, in the presence of 5% CO2 gas, C. vulgaris vitamin B12 content at 2 and 2.5 μM cobalt chloride, were 166.23 ± 1.78 and 173.32 ± 4.23 μg /100 g of dry biomass (7 and 12% higher than control), respectively. However, under controlled condition (ambient air and 2 μM cobalt chloride) vitamin B12 content was 154.9 ± 1.14 μg / 100 g of dry biomass.

In this study, granulated sludge synthesized in a sequence batch reactor (SBR) and then granulated sludge was transferred to continuous feeding and intermittent discharge (CFID) bioreactor. Two independent variables (air flow rate and hydraulic retention time (HRT)) were considered to optimize the process. Subsequently, long term performance (150 days) of the bioreactor was assessed by monitoring nine responses. The process optimization in CFID regime was performed using a central composite face-centered design (CCFD) and analyzed using response surface methodology (RSM). Based on obtained data, the optimum conditions were achieved at HRT of 7-8 h and air flow rate of 2-3.5 L/min. The CFID with granular sludge acted as a high rate bioreactor as the granular sludge could provide high MLSS concentrations (around 10000 mg/L) in a bioreactor.

Wax crystallisation and deposition from offshore reservoirs have been causing serious problems such as plugged pipelines and reduced production flow rates. This issue is receiving more attention from the researchers and for commercial applications due to the shift in trend from using offshore production facilities to pipelines utilization. The aim of this study is the implementation of the Avrami theory to comprehend the mechanism of wax crystallisation to reveal the morphology of wax crystal using gravimetric and differential scanning calorimetry (DSC) analyses. The experiment values obtained from the Avrami’s theory for both gravimetric and DSC techniques shows that the crystals were one-dimensional with rod-like structures.

Dam construction is one of the challenges among large-scale projects of a country. Among different types of dams, due to special features, earth dams are the most kind of dams that were constructed in Iran in the past three decades. Features such as efficiency and stability of earth dams have an important effect on their operation and prevent them to be damaged. Taham dam is clay core dam which is constructed in Zanjan province in Iran. After dam impoundment, the stresses and distribution of pore water pressure of the Taham earth dam were investigated and measured by using the instrumentation installed in dam body. Measured values then compared with the obtained results by numerical analysis of the Dam. For numerical analysis PLAXIS code has been used. This comparison showed that the pore water pressures in the dam is similar with the results of numerical analysis, but the stresses in the dam are lower than results of numerical analysis in most areas of dam.

Geometric imperfections such as radial imperfection, diamond shape, and local dimples could affect the buckling mode and load carrying capacity of axially compressed steel tubular columns. This paper experimentally investigates the effect of radial imperfection on the load carrying capacity of tubular columns. Test samples include 100 specimens with different values for diameter, length, thickness, imperfection amplitude and imperfection location. Considering applications of columns in buildings, bridges, and offshore jackets, diameter to thickness and slenderness ratios were varied between 20-90 and 17-181, respectively. Results showed that depending on the slenderness ratio and the severity of the imperfection, there was a significant difference between buckling loads of perfect and imperfect specimens.

56 ground motions of the bedrock and surface are selected from 28 stiff sites ( site class I and site classⅡ) of the KiK-net station．The peak acceleration, response spectra and shear strain of actual hard sites are calculated by using SHAKE2000 and LSSRLI-1. The similarities and differences between SHAKE2000 and LSSRLI-1 and their differences from measured records are analyzed. It provides a basis for improving the seismic response analysis method of soil layers. The results show that when the soil is not obviously nonlinear, most of the difference in PGA results calculated by SHAKE2000 and LSSRLI-1 can be ignored, and the maximum error of the calculated soil shear strain is also less than 20%. When the soil is highly nonlinear, only a few differences in PGA results can be ignored. The maximum error of shear strain of the soil is greater than 20%. The results of peak acceleration and response spectra calculated by SHAKE2000 and LSSRLI-1 differ greatly from the measured results in most cases. Nevertheless, the probability of having big difference and significant difference between LSSRLI-1 and measured response spectra is greater than SHAKE2000.

Potentially having a destructive influence on the mechanical properties of composite laminates, the invisible phenomenon of delamination frequently occurs under impact loading. In the present study, simulating the performance of long-gauge fiber Bragg grating sensors, impact-induced average strains within laminated composites are utilized to develop a delamination identification technique. First, strain-based modal parameters are extracted from the estimator of frequency response functions using two different approaches. Next, these parameters are employed in various damage detection indicators. Then, the presence, location, and severity of delamination introduced at locations with the least effect on modal changes are detected. The results of different numerical examples with various delamination sizes and positions elucidate the considerable efficiency of average-strain measurements to diagnose delaminated composites.

The restricted earth fault (REF) relay is a type of differential protection which is used for detection of internal ground faults of power transformers. But, during external faults and transformer energization conditions, the probability of current transformer (CT) saturation increases. Thus, the spurious differential current due to CT saturation, can lead to REF relay maloperation. In this paper, a new intelligent REF protection scheme is presented based on the pattern recognition method. In the proposed method, one-cycle data window of differential and neutral currents are used as exemplar patterns of the classifier. The performance of the proposed method is evaluated by obtained data from simulation of a real 230/63 kV power transformer in PSCAD/EMTDC environment. Moreover, in order to accurately simulate the CT behavior during saturation the well-known Jiles-Atherton (JA) model is utilized. The promising obtained results showed that the proposed intelligent method increases the security of the REF relay.

In order to exhaustively exploit the high-level capabilities of shape memory alloys (SMAs), they must be applied in control systems applications. However, because of their hysteretic inherent, dilatory response, and nonlinear behavior, scientists are thwarted in their attempt to design controllers for actuators of such kind. The current study aims at developing a micro-position control system for a novel SMA rod actuator. To do so, the hysteretic behavior of the actuator was simulated in the form of a gray-box Wiener model. Based on the experimental training dataset obtained from the actuator, the hysteresis Wiener model was trained using a PSO algorithm. Afterwards that the identified hysteresis Wiener model was validated, the authors formed a model-in-the-loop (MIL) position control system. Next, a PSO algorithm was again set to find the best controller parameters regarding some performance criteria. At the end, implemented on the fabricated prototype (the experimental setup), the designed control system shared such excellent accuracy that makes the fabricated actuator amenable to micro-positioning applications.

Despite recent advances in face recognition systems, they suffer from serious problems because of the extensive types of changes in human face (changes like light, glasses, head tilt, different emotional modes). Each one of these factors can significantly reduce the face recognition accuracy. Several methods have been proposed by researchers to overcome these problems. Nonetheless, in recent years, using thermal images has gain more attention among the introduced solutions as an effective and unique solution. This article studies the performance of sparse processing techniques when facing with challenges of face recognition problem in thermal images. Also, the potential of the sparse classifier algorithm to receive information directly from input images without using any feature extraction algorithms was studied. The obtained results indicated that the sparse processing techniques outperform the Eigenface and KNN algorithms in terms of addressing the challenges of thermal images. In this work, USTC NVIN and CBSR NIR face datasets were used for simulation purposes. These datasets include the images with different emotional states (sad, happy, etc.) captured in different light conditions; also the images are captured both with and without wearing glasses. Simulation results have shown that sparse classifier can be an effective algorithm for the face recognition problem in thermal images.

In this paper, a green transportation location problem is considered with uncertain demand parameter. Increasing robustness influences the number of trucks for sending goods and products, caused consequently, increase the air pollution. In this paper, two green approaches are introduced which demand is the main uncertain parameter in both. These approaches are addressed to provide a trade-off between using available trucks and buying new hybrid trucks for evaluating total costs beside air pollution. Due to growing complexity, a Lagrangian decomposition algorithm is applied to find a tight lower bound for each approach. In this propounded algorithm, the main model is decomposed into master and subproblems to speed up convergence with a tight gap. Finally, the suggested algorithm is compared with commercial solver regarding total cost and computational time. Due to computational results for the proposed approach, the Lagrangian decomposition algorithm is provided a close lower bound in less time against commercial solver.

Piston aluminum alloys have different intermetallic phases, such as Cu3Al, Mg2Si ,and AlNi phases. The morphology and the distribution of such phases have important roles on mechanical properties of the piston material. Therefore, in this research, various ageing heat treatments on the mentioned material were done and the microstructural feature and the hardness were studied. Obtained results showed that solutioning at 515 °C for 7 hours and ageing at 205 °C for 7 hours, was the superior heat treatment process, since such treatment led to increase the hardness value to its highest value (153 BHN) for the piston aluminum alloy. This heat treatment caused to increase the size of Si particles obviously and caused to precipitate other intermetallic phases of Al (Ni,Cu) and Ni-Si. Additionally, solutioning at 500 °C for 5 hours and ageing at 180 °C for 9 hours resulted in coarsening Si and Al-Ni participates in the longitudinal direction, which was caused to increase the hardness value to 137 BHN. Energy dispersive X-ray spectroscopy (EDS) results indicated that when the specimen aged at 230 °C for 5 hours, other intermetallic phases such as Al (Ni,Si) and Mg2Si appeared in the matrix.

Austenitic stainless steel SS304 grade was welded with active Tungsten Inert Gas (TIG) welding process by applying a flux paste made of SiO2 powder and acetone. SiO2 flux application improves the weld bead depth with a simultaneous reduction in weld bead width. The improvement in penetration results from arc constriction and reversal of Marangoni convection. Experimental studies revealed that the SiO2 flux assisted TIG welding can enhance the weld bead penetration by more than 100%. Full depth welds up to 6mm were obtained by applying SiO2 flux. Microstructure reveals a reduction in ferrite formation in fusion zone by applying SiO2 flux. Samples welded with flux exhibits reduction in tensile strength and improvement in impact strength. Fractography of the tensile test specimens reveals the presence of oxide inclusions in the samples welded with flux. The relation of ferrite content and mechanical properties are presented in this paper.

Today, researchers exploit hybrid craft more than they used to be. The main reason is that they need to high speed as well as extra portability. For instance, a famous hybrid craft is named Hysucat, was designed through the combination of catamaran and hydrofoil. Catamarans, a type of multihull boats, have always considered by designers because of their simultaneous supply of high speed and stability. These boats hold high drag despite more wetted surface as well. By using hydrofoil the wetted surface reduces, and then the drag of boat will decline. Meanwhile, sketches in the layout of hydrofoil processes notice to weight and center of gravity. This paper investigated application of hydrofoil in the high speed catamaran with considering different conditions in terms of center of gravity and load conditions. The model has exploited in the three states of loading (partial, ballast and over) and two centers of gravity for each diverse weight. Hence, nine series tests in towing tank have been carried out on the model boat in scale 1 ratio to 11.43. Eventually, results were computed to full scale boat by Froude number and ITTC model. According to the test results, usage of the hydrofoil brings about 50% drag reduction.

In a shell and tube heat exchanger, the failure of tube-to-tubesheet welds results in high-pressure water jet which erodes the refractory in front of the tubesheet. Finite element method was employed to simulate the welding process and post weld heat treatment (PWHT) to find the factors affecting the failure in tube-to-tubesheet weldments. Residual stresses in two different geometries of tube-to-tubesheet weldment were calculated through uncoupled thermal-structural analysis. The results showed that the values of residual stresses are higher in heat exchanger of site 1 than site 2 due to more weld passes and geometry of connection. Also, the maximum stress in site 1 occurs at the shellside face of tubesheet while it is on the weld toe in site 2. High tensile residual stresses, especially in Site 1, reduce the tubesheet life. Therefore, performing an efficient PWHT is vital. The PWHT simulation indicated that the process designed is effective for both sites by reducing the residual stress significantly. In addition, the effect of stress concentration was examined on both sites. Moreover, the stress concentration factor in site 1 is as twice as in site 2 and it is the main reason for more failures in site 1.

This paper focuses on the problem of accurate Fault Characteristic Frequency (FCF) estimation of rolling bearing. Teager-Kaiser Energy Operator (TKEO) demodulation has been applied widely to rolling bearing fault detection. FCF can be extracted from vibration signals, which is pre-treatment by TEKO demodulation method. However, because of strong noise background of fault vibration signal, it is difficult to extract FCF with high precision. In this paper, the improved algorithm of rolling bearing fault diagnosis is analyzed. Based on the envelope analysis by TKEO demodulation, it combines zero padding technique and the Improved Iterative Windowed Interpolation DFT (IIWIpDFT) algorithm to correct demodulated signal. Experimental result shows that the proposed algorithm decreases Root Mean Square Error (RMSE) of FCF(inner race) form about 2Hz~5.5Hz to about 0.5Hz for short data length, the same treatment also decreases RMSE form about 1.1Hz~3Hz to about 0.4~0.5Hz for longer data length in most cases. Meanwhile, the RMSE of FCF (outer race) improved 2.3 to 84.5% as compared to the application of traditional TEKO demodulation alone.

The elimination of the FexAly type phases was considered the solution to low ductility presented in aluminum-steel welded joints. Recently, the researches do not seek the suppression but the control of the thickness of these compounds. In this work, Al-Fe joints were manufactured by solid state and fusion welding, looking for controlling the formation of intermetallic compounds. Temperature measurements were carried out during the welding. The joints interface was characterized using optical and scanning electronic microscopy, aided by chemical composition measures with X-EDS. The microstructural characterization at the interface of aluminum-steel joints, in solid state welded joints, demonstrated the absence of intermetallic compounds, which is attributed to the low temperature reached during the process - less than 300 ° C. In the case of fusion joints, it has observed the permanent formation of intermetallic compounds whose thickness varies significantly with the heat input.

Examining the cooling rate using impingement of air jet finds a wide application in electronic packaging and micro-scale fluid heat interaction systems, While the prediction of Nusselt profile at low nozzle-target spacing is a big issue. The plot of area average Nusselt number magnitude against the nozzle-target spacing (Z/d) shows a gradual decrement in the profile upto Z/d = 1 and beyond that is steady. The present work aims in anticipating the profile of Nusselt number using semi-empirical relations. These semi-empirical relations are derived using using regression analysis which is carried out between Re, Z/d and local Nusselt number.The data required for regression are obtained through computation. Numerical simulations are accomplished for different impinging and geometric parameters. The semi-empirical power law relations are correlated between Z/d and Re. These are predicted differently for four distinct region of heat sink (stagnant point, near jet region, far jet region, near wall region). The developed correlations are found to bear negative exponent with Z/d and positive exponent with Re. The negative power of r/d and Z/d varies from 0.23 – 0.64 and 0.0025 – 0.38, respectively, While the exponents of Re varies in the positive range of 0.4-0.76

In this work, a magnetorheological (MR) damper based above-knee prosthesis is design and evaluated based on its performance in swing phase and in stance phase. Initially, a dynamic system model for swing phase of a prosthetic leg incorporating a single-axis knee with ideal MR damper was built. The dynamic properties of the damper are represented with Bingham parametric model. From Bingham model, governing damper parameters that determine the damping force and piston displacement of the damper are identified and optimized so as to enable the single-axis knee to nearly mimick the natural swing phase trajectory of a healthy person for level-ground walking as obtained from experimental data. Then, with the optimal damper parameters, an MR damper valve constrained in a desired cylindrical volume is developed. Finally, the prosthetic knee with the MR damper is evaluated for its performance during stance phase, based on ISO standard loading condition for the intended application. The results show that, compare to Rheo knee®, the MR damper based prosthetic knee has achieved up to 68% reduction by volume and 40% reduction by weight.

The recent penetration of renewable sources in the energy system caused a transformation of the needs of the distribution system and amplified the need of energy storage systems to properly balance the electricity grid. Among electrochemical energy storage devices, all vanadium flow batteries are those of the most promising technologies due to their high efficiency, long lifetime, reliability and independence between installed power and storage capacity. Oppositely, the low energy density and the high costs are preventing this technology from spreading at commercial level, even if many are the opportunities of improvement. In this article, a serpentine flow fields are tested using a numerical simulation for the all vanadium redox flow battery. The development of a three dimensional model for the cathode of a vanadium redox flow batteries is presented. The results were discussed in terms of the uniformity of the reactant distribution, overpotential, velocity and state of the charge through the cell.

The welding of materials by applying Friction Stir Welding technique is a new solid-state joining technique. The main advantage of this method compared to the traditional joining process is that it minimizes problem-related to metal resolidification as the method incorporates no melting phase. In this experimental work, the effect of friction stir welding (FSW) technique on the microstructure and mechanical properties of the cast composite matrix AA6063 reinforced with 7wt % SiC particles is studied. Friction stir welding, owing to the simultaneous effect of intense plastic deformation and frictional heat generated throughout welding, had impacts each on the reinforcement agents and the matrix alloy. FSW produced a notable reduction in the size of reinforcement agents and their homogeneous distribution in the weld region. It also induced the grain refinement due to dynamic recrystallization of the aluminum matrix alloy in the weld area. The frictional heat generated during friction stir welding had impacts on the growth, dissolution and reprecipitation of the hardening precipitates. The microstructural changes resulted in improved mechanical properties such as UTS, elongation, and hardness of the joint. A joint efficiency of 98.84% was observed for the welded joint. The XRD and EDX analysis of the welded area confirmed that there was no formation of any other compound due to the frictional heat produced during welding. The SEM fracture morphology of the welded joint revealed that the fracture behavior was changed from ductile to brittle following to FSW.

Deformation of the silo wall due to the single ball impact is modeled in ANSYS. The material in silo, as a Winkler bed, is replaced by spring-damper elements and the spring stiffness and damper coefficients are evaluated of the granular material and wall properties. The granular material deformation under the specified force is measured to evaluate the granular stiffness to be used for determining the appropriate spring stiffness in ANSYS model. Geometrical parameters and boundary conditions are set according to the properties of a laboratory silo containing magnetite concentrate. Effects of impact parameters including the ball size and the impact position on the hopper displacement are taken into account. Comparison of simulation results with experimental data confirms that the wall displacement is an indicator of the ability of impact to solve obstruction. Simulation will be an alternative to expensive and time consuming experimental procedures for specifying the optimal impacts for obstruction solution.

The interaction of work fluid mechanics with that of the rotary system itself, basically composed of axes, bearings and rotors, is performed by inserting equivalent dynamic coefficients in the mathematical model of the rotor, the latter being obtained by the finite element method. In this paper, the dynamic coefficients of inertia, stiffness and damping of the flat seals analyzed here are evaluated, from the point of view of the dependence of the geometric characteristics of the seals and the operating conditions of the machine. Then, once incorporated into the entire rotating system model, the flow seals are also analyzed from the point of view of their influence on the overall dynamic response of the rotating machine. The mechanical seals of the cylindrical, conical and stepped type were analyzed, determining, for this purpose, the dynamic coefficients of damping, stiffness and inertia. In addition, the influence of physical and operational parameters of the system in relation to these elements were verified. Therefore, the modeling and analysis of flow seals are inserted in an interesting and promising way in the context of the global research theme in rotary machines.