Yanbu Journal of Engineering and Science (YJES)
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202 research outputs found
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Empirical Model for Moon Sighting
No full textAn empirical model is developed to precisely identify the new crescent visibility of each Hijri month. The model is based on the actual real measurements of the moon motion. The model used the sinusoidal behaviour to model the relative motion of the lunar with respect to the earth. The model stability is achieved by the exact matching between the sine wave and the phases of the moon crescent, with respect to an observer from the earth. The accuracy of the model is granted by using the most accurate measurements for the motion of the moon. The model is applied to 18 Hijri months, from Shaban 1443 H to Muharam 1445 H. The moon sighting of these 18 months are obtained and compared with three references, the Um-Alqura calendar, Al-Tawqifat Alelhamih book and the moon visibility curves. The comparisons are discussed and concluded the reliability of the present model
SURFACE FLOW GENERATION MECHANISM INDUCED BY A BUBBLE PLUME
No full textThe technique of using a surface flow generated by the bubble plume is utilized as one of effective ways to control and collect the surface floating substances in naval systems, lakes, seas, rivers, oceans, as well as in various kinds of engineering processes handling a free surface. In the past, however, the detailed mechanism of the surface flow generation process has not been measured. The motivation of this paper is the demand to know the characteristics of the surface flow, which depends on the gas flow rate, the bubble size, and the internal two-phase flow structure of the bubble plume. In this paper, the two- dimensional flow analysis based on Eulerrian-Lagrangian model and the particle tracking velocimetry measurement have carried out in order to elucidate the surface flow generation process in detail. The present results explore that surface velocity profile can be predicted by Eulerian- Lagrangian model in good agreement with experimental results. Maximum velocity of the surface flow increases as small bubble size is supplied. The surface flow is effectively generated in case of bubble plume compared to liquid jet flow because distortion point appears in the vicinity of surface. The data are obtained for two kinds of visualized images: the first that of the upper view of the surface flow, and the second that of the surface flow generation region under the free surface
THEORETICAL APPROACH TO STUDY SELF-ORGANIZING PROPERTIES OF A NEMATIC LIQUID CRYSTAL WITH CARBON NANOSOLID MODELS
No full textA theoretical study on stable geometries of a nematic liquid crystal (LC) molecule (4- methoxybenzylidene-4\u27-n-butylaniline (MBBA)) assembled on the carbon nanosolid (CNS) surface models (graphite sheet and carbon nanotube (CNT): zigzag, armchair) has been carried out by using semi-empirical molecular quantum calculations within the parameterized model number 3method as implemented in the Hyperchem package. The interaction of π,π-stacking between the MBBA molecules present on the CNS wall led to the formation of local short-range orientational order due to the LC-CNS binding energy. The binding energy of the LC molecule on the CNS surface was the typical van der Waals interaction. The results of this study showed that the assembly of LC-zigzag CNT system was a preferable model compared with the other available models
Grid-Connected PV System Statistics and Evaluation; Review
No full textToday, the grid-connected photovoltaic (PV) power system plays a significant role in generating electrical energy by making use of the sun’s rays, then converting it into usable electrical energy and connecting it to the electrical grid. This process can be done by connecting the PV panel to the DC/DC converter then there will be a controlled DC/AC inverter. This paper discusses a literature review about the PV system, types, advantages, and disadvantages, generating level ratings and levels, statistics, and comparisons between countries worldwide. In addition, a review of the control method presented in PV systems
SOIL DRYNESS AND ITS EFFECT ON TOXIC COPPER MOBILITY
No full textCopper is applied to many crops as a fungicide/bactericide, including plasticulture tomato growing operations. Therefore, a laboratory study was undertaken to determine if this agricultural copper can migrate in soil and to determine the mechanisms that account for the movement through soil to the subsurface. Total Organic Carbon (TOC), dryness and its temperature cycle, and water content of the soil were selected for study. These factors were investigated in both batch and continuous flow (column) processes. Results demonstrated that copper mobility through soil columns was associated with TOC mobility, and soil drying had a major effect on both copper and TOC mobility. The concentration of copper eluted from columns containing dried soils was as high as 120 µg/l copper and 150 mg/l TOC. The copper and TOC concentrations from dried soils were very high compared with those containing wet soils. The extent of dryness was found to affect mobility. A first-flush-pattern for both copper and TOC was observed in all columns studies
AN EXPERIMENTAL STUDY OF THE TEMPERATURE DISTRIBUTION DUE TO BENZENE FIRE UNDER FORCED VENTILATION
No full textThis work aims to study the effective parameters on forced ventilation by which the fire can be put under control. There are many parameters which specify the forced ventilation such as angle of louvers \u27supply air grill\u27; this parameter was investigated experimentally using a modified test rig in order to supply different ventilation rates into the compartment with different angle of louvers \u27supply air grill\u27 while different types of fuel with different masses were used. In this paper was concerned on benzene fuel of 13.2 gram when the fuel mass less than 13.2 g no clear differences in temperature distribution. To perform this study a modified test room was designed. Results of the study show that the effect of angle of louvers \u27supply air grill\u27 and ventilation rate on fire depression (minimum fire duration) in a compartment is mainly represented in the high values of angle of louvers \u27supply air grill\u27 by 75° (equivalent ventilation factor 0.0215 m2) and low values of speed of extracting fans (equivalent ventilation rate 0.067 m³/s) for benzene (gasoline fuel) at different fuel masses. Also, results indicate that a decreasing in angle of louvers \u27supply air grill\u27 and increasing in ventilation rates result in undesirable effects as the fire duration increased
DSP-BASED CONTROL OF BOOST PFC AC-DC CONVERTERS USING PREDICTIVE CONTROL
No full textFor digital power-factor correction (PFC) control methods, the duty cycle is calculated in every switching period. One main implementation barrier is the limited switching frequency, due to the limited processor speed. In this paper a predictive digital PFC control method is proposed to solve this problem. The proposed control method generates all the duty cycles in advance, based on the reference current and sensed inductor current, input voltage and output voltage. It requires only one multiplication and three addition operations for digital implementation, so that the proposed PFC control method can be implemented (by using a low cost DSP or microprocessor to achieve high switching frequency). A power factor correction rectifier, that requires a current control with a rectified sinusoidal reference, is controlled using three methods: i) Average current mode control ii) Hysteresis control iii) Proposed predictive control. All these controllers are implemented on a digital platform. Simulation and experimental results show that predictive control has low THD, high PF, lower cost and better performance than the others control methods (due to its lower calculation requirement). Also, sinusoidal input current can be achieved under a non-sinusoidal input voltage condition for predictive control only
CREATING AND MEASURING RELATIVE HARDNESS FEELING VIA MASTER-SLAVE HAPTIC GRIPPER
No full textThis paper discusses the completed work in designing a master-slave haptic gripper system aiming to recreate the relative hardness feeling of different real test objects at the slave gripper to the user at the master gripper. The main contribution of this paper is to prove the feasibility of recreating the relative hardness feeling of real objects to the users as oppose to recreating the hardness feeling of virtual objects which has been proven to be feasible for quite some time. Three experiments involving twenty test subjects and fifteen pairs of test object combinations are conducted to evaluate the performance of the master-slave haptic gripper system. Experiments show that users at the master gripper end are able to differentiate the relative hardness level of the test objects handled by the slave gripper. The secondary contribution of this paper is the introduction of haptic index defined as a set of numerical value that describe the otherwise immeasurable subjective relative hardness level of an object felt by human. The proposed haptic index can contribute towards designing better robots and controllers that can feel the relative hardness of objects like in the human world
MODELING AND NEURAL CONTROL OF QUADROTOR HELICOPTER
No full textQuadrotor Helicopter or simply quadrotor is rotorcraft that has four lift-generating propellers. Two of the propellers spin clock wise and the other two counter-clockwise. Control of the machine can be achieved by varying relative speed of the propellers. Quadrotor concept is not new, however the modern quadrotors are mostly unmanned. Advancement in miniaturized IMU technology, availability of high speed brushless motors and high power to weight ratio Li-Polymer battery technology, quadrotors can now be successfully designed and fabricated. This paper proposes a mathematical model of quadrotor dynamics and a control scheme based on Direct Inverse Neural Control. In modeling A simplified approach is adopted where the gyroscopic effect and air friction on frame of machine has been neglected, resulting in a simplified model, which is useful for designing a controller to stabilize the plant in hover state. Proposed model is non-linear since the rotor dynamics are a function of square of motor inputs. The neural network based controller, exploits the multiple layer perceptron trained by the back propagation algorithm. Direct inverse control scheme uses the idea of canceling out the dynamics of a plant by training the controller to approximate the inverse of the plant. This scheme however requires the plant to have a stable inverse
DEVELOPMENT OF AN OPTIMAL PATH PLANNING USING ELITE OPPOSITION BASED BAT ALGORITHM FOR A MOBILE ROBOT
No full textThis research work presents the development of an optimal path planning using elite opposition based bat algorithm (EOBA) for mobile robot, such that the robot avoids obstacle(s) without making contact with them. The bat algorithm (BA) is a nature. inspired meta-heuristic algorithm that works on the basis of the echolocation behavior of bat. It, however, has a poor exploration capability leading to it easily getting stuck in local optima. The EOBA is developed by modifying the BA with the elite opposition-based learning (EOBL) so as to diversify the solution search space and the inertial weight in order to balance its exploration and exploitation. The performance of the proposed path planning technique was compared with that of the standard BA based on the ability to generate an optimal path for a mobile robot in a developed simulation environment. The simulation results showed that EOBA provide an optimal path with minimum elapsed time as compared to that of the standard BA. All simulations were carried out using MATLAB R20136