INTERNATIONAL JOURNAL OF ENGINEERING
Year:2016 | Volume:29 | Issue:2 (TRANSACTIONS B: APPLICATIONS)|Papers Count:17

This paper deals with the study and comparison of passive and active landing gear system of the aircraft and dynamic responses due to runway irregularities while the aircraft is taxying. The dynamic load and vibration caused by the unevenness of runway will result in airframe fatigue, discomfort of passengers and the reduction of the pilot’s ability to control the aircraft. One of the objectives of this paper is to obtain a mathematical model for the passive and active landing gears for full aircraft model. The main purpose of current paper is to design linear quadratic regulator (LQR) for active landing gear system that chooses damping and stiffness performance of suspension system as control object. Sometimes conventional feedback controller may not perform well because of the variation in process dynamics due to nonlinear actuator in active control system, change in environmental conditions and variation in the character of the disturbances. To overcome the above problem, we have designed a controller for a second order system based on Linear Quadratic Regulator. The performance of active system is compared with the passive landing gear system by numerical simulation. The results of current paper in compared with the previous work mentioned in reference, demonstrates 37.04% improvement in body acceleration, 20% in fuselage displacement and 13.8% in the shock strut travel. The active landing gear system is able to increase the ride comfort and good track holding by reducing the fuselage acceleration and displacement and load induced to airframe caused by runway excitation.

Curcumin is a natural bioactive compound originated from the rhizomes of turmeric (Curcuma longa L.). This study was performed to investigate formic acid and microwave assisted extraction of curcumin from turmeric (Curcuma longa L.). In order to enhance the curcumin extraction, different parameters such as particle size, effect of pretreatment with water, radiation intensity and type of solvent were investigated. For analysis of curcumin content, two methods were developed. Spectrophotometric methods at the stage of optimization and high performance liquid chromatography (HPLC) for determination of the purity of curcumin were used. At particle size of 0.21mm and input power of 100W using acetone as organic solvent, the highest curcumin extraction yields were achieved. The results showed that water is a suitable modifier for the pretreatment of turmeric with microwave irradiation. For purification of curcumin in HPLC analysis, methanol and water were used as co-solvents. Maximum obtained curcumin purity was 82.4%.

In this work, batch studies were conducted to evaluate the effect of environmental factors on the rate of Cr (VI) reduction from synthetic wastewater of metal plating industry by Bacillus cereus. The effect of different inoculum volumes (5, 10, 15 and 20 mL), pH (5, 7 and 9), temperatures (20, 30 and 40 °C) and initial concentrations of Cr (VI) (10, 50, 100 and 200 mg/L) for the best performance of chromium removal were investigated during 72 h of cultivation by Bacillus cereus. Complete reduction of Cr (VI) by Bacillus cereus was achieved after 48 h of incubation under optimized conditions of pH 7, inoculum volume of 5 mL, initial chromium concentration of 50 mg/L, and temperature of 40 oC. The results showed the highest rate of reduction at the lowest Cr (VI) concentration (0.104 mg/L.h). Atomic absorption spectroscopy analyses under optimized conditions showed the concentration of Cr (III) in the culture supernatant was 49 mg/L after 48 h. The presence of almost all the reduced Cr (III) in the supernatant revealed Cr (VI) -reductase in Bacillus cereus is mainly associated with the soluble fraction of the enzyme. High Cr (VI) concentration resistance and high Cr (VI) reducing ability of Bacillus cereus make it a suitable candidate for bioremediation.

In this article, a novel nano sodalite zeolite was synthesized and characterized by X-ray diffraction, scanning electronic microscopy (SEM) and infrared spectroscopy and evaluated in order to facilitate the sorption of strontium ions from aqueous solutions in batch operations onto acid treated zeolite with dilute H2SO4 solutions. The optimum conditions of sorption were found as follows: a sorbent amount of 0.25 g in 100 mL of strontium solution (50 mg/L), contact time, pH and temperature of 80 min, 6 and 20oC, respectively. To study the kinetics of removal process, three equations, i.e. Morris–Weber, Lagergren (pseudo first order) and pseudo second order were used. The strontium sorption process was well described by the pseudo second order (type 2) kinetic model. The Langmuir, Freundlich, Dubnin-Randkovich (D-R) and Temkin models were subjected to sorption data to estimate sorption capacity, intensity and energy. An evaluation of the thermodynamic parameters including ΔH, ΔS and ΔG was done. It was found out from thermodynamic parameters that the sorption of strontium onto zeolite was feasible, spontaneous and endothermic under studied conditions.

Uranium (VI) sorption using an anionic exchanger resin, namely Amberlite IRA910, in the presence of sulfate anions was the subject of current study. Batch sorption experiments were carried out to evaluate the influence of operational parameters such as pH, contact time, initial concentration and existence of various anions (including phosphate, sulfate, chloride, fluoride, and nitrate) in the solution on Amberlite IRA910 sorption behavior. Experiments revealed that uranium adsorption was fulfiled at pH>3 and 50 min to amount of 80%. Kinetics study revealed that the pseudo-second-order model showed better curve-fitting regression of the experimental data than the pseudo-first-order one. Freundlich isotherm was also provided well mathematical description of sorption process than the Langmuir one. Uranium adsorption capacity of the sorbent was 1666.6 mmol g-1. It was also revealed that the existence of various anion species in the solution could strongly affect the sorption of uranium using the Amberlite IRA910 anion exchanger resin

Iran is a country with high seismicity while Tehran, the capital city is home to more than 10 million people which are located on the highest seismic zone of the country. There exist 153 gas stations throughout the metropolitan which are constructed to old building codes with little or no attention to the seismic considerations. This study was conducted under a financial support by the ministry of Oil. First as built drawings were collected and studied in details. A set of new drawings were then created by detailed inspection and also some destructive tastings. This study then looked at the both mechanical and structural properties of the whole structures and their seismic behavior. This procedure was conducted for the main building, piping, tanks, shed structures as well as pumps and mechanical equipments. The loading was considered by the seismic provisions of the Iranian seismic provisions and static load analysis was carried out for the structures. This paper shows the general approach and also the detail procedure used for one such stations.

This paper investigates the effect of moisture content on interface shear strength between offshore clay and steel plate. Although, sensitive and high plasticity offshore clay deposits are widely distributed in Malaysia and many other countries in the world, and steel is a vital construction material for many structures, research works on interaction between offshore clay and steel surface are relatively scarce. This study aims to evaluate interface shear strength of offshore clay with various steel surfaces, namely smooth, rough, and corroded. To achieve such aim, direct shear tests were conducted to assess the effect of moisture content and surface roughness on the interface shear strength. The normal stresses were ranged to be 50, 100, and 150 kPa. It was found that, the interface shear strength of offshore clay with rough steel significantly increased by almost 1.5 folds. It was further discovered that, addition of water content induced a progressive decrease in the interface shear strength. In summary, it has been observed that rough steel surface higher than the smooth and corroded steel surface enables a better interaction with offshore clay, enhancing the interface friction angle. The results developed in this research work can contribute a cost-effective design of structures in offshore clay.

The use of pervious concrete has been significantly considered in recent years. This consideration is due to the properties of pervious concrete in relation to the environmental sustainability that is utilized in the effective management of the runoff from rainfall. Coal extraction and rice husk obtained from milling, produces wastes that have no application and followed by environmental pollution. The purpose of current research is to evaluate the effects of coal waste ash (CWA) and rice husk ash (RHA) and to compare the mechanical properties of pervious concrete pavement with concrete having ash. Therefore, both of these wastes were burned and after that XRF testing it was observed that they have achieved pozzolanic properties. In order to strengthen pozzoli cement, certain amount of CWA and RHA as a cement replacement were added to concrete mixtures. The results indicated that the addition of RHA and CWA improved the mechanical properties of pervious concrete. However, the optimum percentage is dramatically varying. Among these, the effectiveness of CWA is more significant compared to RHA. By increasing the amount of CWA and RHA to the optimum level, the permeability of the pervious concrete had simultaneously decreased. However, beyond the optimum level, it may show inverse respond.

In this study, a robust controller for voltage regulation of a POESLL converter operated in continuous conduction mode is presented. The POESLL converter is a DC/DC converter with a high voltage gain. DC/DC converters are used in telecommunication systems, power sources and industrial applications. Owing to the switching operation, the structure of the POESLL converter is non-linear. In addition, because of the load and input voltage variations, the structure of the POESLL converter is time-varying. In order to regulate the output voltage of the POESLL converter, a non-linear controller is required. The proposed controller is developed based on constant frequency sliding mode method. The sliding mode controllers can cope with the non-linear and time-varying structure of the DC/DC converters. The performance of the proposed controller is studied in PSIM software. A laboratory model of the proposed controller has been implemented. In this paper, design, simulations and experimental results are presented to show the effective performance of the proposed controller for voltage regulation of the POESLL converter.

This paper addresses a multi-objective mathematical model for the mixed-model two-sided assembly line balancing and worker assignment with different skills. In this problem, the operation time of each task is dependent on the skill of the worker. The following objective functions are considered in the mathematical model: (1) minimizing the number of mated-stations, (2) minimizing the number of stations, and (3) minimizing the total human cost for a given cycle time. Furthermore, maximizing the weighted line efficiency and minimizing the weighted smoothness are two indices considered simultaneously in this paper. Since this problem is well-known as NP-hard class, a particle swarm optimization (PSO) algorithm is developed to solve it. The performance of the proposed PSO algorithm is evaluated with a simulated annealing (SA) algorithm existing in the literature over several benchmarked test problems for the conditions of the current problem in terms of running time and solution quality. The results show the proposed algorithm is an efficient algorithm.

The aim of present study is to investigate the effect of various parameters such as length, thickness, density, shear modulus of the core and Young modulus of skins for various boundary conditions, clamped-free and simply supported, by applying the model of Khalili et al. for free vibration analysis of sandwich beams by using finite element methods. The core density is taken in consideration. The flexural vibrations of beams are analyzed by the finite element method, using the stiffness and mass matrix of beam element with three degrees of freedom per node. The three first natural frequencies are calculated by using Matlab commercial software. A comparison is established between three different lengths for each configuration. There is a good agreement between the results obtained by the present study with the results obtained by Khalili et al.

  This paper investigates the possibility and effectiveness of multi-mode vibration control of a plate through real-time FPGA (Field Programmable Gate Array) implementation. This type of embedded system offers true parallel and high throughput computation abilities. The control object is an aluminum panel, clamped to a Perspex box’s upper side. Two types of control laws are studied. The first belongs to non-model based control. This control law is designed to generate active damping within the designed bandwidth. The second control law is model based H-infinity robust control. A system identification process is needed before the controller comes out. Each of the control laws is implemented on a FPGA target, which is powerful enough to achieve high throughput control loop rates. The experimental control results demonstrate that the non-model based control law has sufficient authority to suppress the interesting modes. The model-based robust control law’s control performance is not so positive compared to the previous method. Therefore, it is not recommended for this application. College of Automation, Nanjing University of Posts and Telecommunications, Nanjing, China

This article describes a 3D CFD (computational fluid dynamics) simulation implementation of the stepped planing hull in calm water. The turbulent free surface flow around the stepped planing hull is computed with a RANSE method, using the solver ANSYS-CFX. The turbulence model used is standard k–e. In order to simulate the disturbed free surface, volume of fluid (VOF) model is implemented. The CFD model has been firstly validated using the available experimental data. The numerical results of drag, pressure distribution, wetted surface, water spray, wake profile and wave generated by the planing hull are presented and discussed at various speeds. Wake profiles calculated from present model are also compared with the ones calculated from Savitsky’s emprical equations at different speeds.

In the present study, the effect of random distribution of reactants and products on laminar, 2D and steady-state flame propagation in aluminum particles has been investigated. The flame structure is assumed to consist of a preheat zone, a reaction zone and a post flame zone. It is presumed that in the preheat zone particles are heated and reaction does not exist. Energy conservation equations of laminar flame had been solved two-dimensionally for different zones and algebraic equations of flame speed are obtained. Finally, gas temperature distribution in different flame zones in the channel and also flame speed changes in terms of particles diameter, equivalence ratio, and channel width in random media are compared with previous experimental and theoretical results. The results show a reasonable compatibility with this theory and experimental data.

In this paper, the intake manifold as the most effective part on engine’s volumetric efficiency was investigated in detail with emphesizing on the flow behavior and characterestics. Eight different designs were prepared and imported to the CFD software. Five objective functions with different weights were applied and investigated by TOPSIS method. The weights were supposed so that, one of the objectives was dominant compared to others. Mass flow rate, mass flow rate deviation between runners, flow coefficient, turbulence intensity and velocity at the runner end were considered as objective functions for flow detail assesment. Then, all geometrical dimentions were applied to a verified ESC. The engine simulation model was developed for I3 engine considering turbulence combustion model named " SI-TURB". The ESC was validated by experimental combustion profile data. The experimental and numerical results had good compatibality, so that the ESC could simulate and predict the engine performance by 6.15% accuracy. This paper shows that the hybridization of 3D analysis with ESC in the closed loop way is mandatory for developing of IM in order to have the best compromising design. Finally, combination of CFD and ESC revealed, considering the same weights for objective functions in TOPSIS, good performance in point of engine power out put.

In most of sheet forming processes, production of the final parts with minimum thickness variation and low required force is important. In this research, minimization of the sheet thinning and forming force in the hydraulic deep drawing process was studied. Firstly, the process was simulated using the finite element method (FEM) and the simulation model was verified compared to experimental results. Then the sheet thinning ratio and punch force were modeled as objective functions using the response surface methodology (RSM). In this model, process parameters including punch nose radius, die entrance radius and maximum fluid pressure were the input variables. Required experiments for the RSM were designed using the central composite design (CCD) method and performed by FEM. Finally, optimum point of the parameters was obtained by multi-objective optimization of the objective functions using the desirability function method based on response surface model and then evaluated. In addition, optimum ranges of the parameters were determined using overlying contour plots. Results showed that the response surface models had good adequacy. According to this model, increasing of the punch nose radius and die entrance radius lead to decreasing of thinning ratio and increasing the maximum punch force. Also the maximum punch force increases by increasing the maximum fluid pressure. Optimization results represent reduction of the thinning ratio almost 10% compared with conventional results.

Energy delivery at well construction in regions with hard climate is distinguished by variable demand in electric and heat power. Energy consumption of drilling equipment, production and living facilities varies greatly during the year, depending on power load charts and climate conditions. Power supply of remote well construction sites is mostly accomplished by operating autonomous power sources, such as gas turbine units. In this regard efficiency enhancement of power units is seen as relevant task. Thus combined heat and power structure for efficient power supply of well construction operations is offered by the authors. Required amount of electric and heat energy at well drilling in harsh climate is calculated in the paper. Also scheme of energy delivering structure based on gas turbine units with flue gases heat utilization for rig objects heating is developed in the article.