Al-Nahrain Journal for Engineering Sciences
Development of High Performance (Mechanical and Wear Properties) of AA 6061-Hybrid Nano Composites Via Liquid Metallurgy Route
This research is devoted to study the influence of different weight percent concerning to the additions of Ti and Cu on mechanical and tribological properties of AA6061. The composite materials consist of different weight percentage of Ti (0.2, 0.4, and 0.6) wt% and constant weight percentage of Cu (0.2) wt% which were fabricated by liquid metallurgy route technique. Microstructural characterization and phases have been examined by using SEM (scanning electron microscopic).SEM examination showed uniform distribution of nano Ti and Cu in AA6061. The consequences of mechanical tests demonstrated clear enhancement in mechanical properties, such as ultimate tensile strength, yield strength, young modulus, ductility% and hardness at additive percentage of 0.4% Ti+0.2%Cu nano particles incorporated into molten AA6061. Percentage of enhancement ultimate tensile strength is about 73.3%, yield strength about 82.7%, young modulus is about 21.2%, the Vickers hardness about 42.6% and the decreasing in ductility was about 25.2% compared with the metal matrix (AA6061). The wear rate test was performed by using pin on disc rig for both hybrid nano composite and base metal (AA6061) under various loads (10,15and 20) N with sliding speed (1.282) m/sec at a (10) min’s time. The results showed a decrease in wear rate at 0.4%Ti+0.2%Cu compared with the base metal (AA6061). Improvement percentage of wear rate is about 105% at 20 N load.
Copyright (c) 2019 Al-Nahrain Journal for Engineering Sciences
An Investigation of the Shearing Forces Using Blanked Carbon Steel Sheets
An important challenge confronted when using blanking to machine sheet metal is the treatment of the shearing force in demand for great strength and heavy stock. One of the methods used to decrease the force wanted is the increase of a punch shear angle. In this work, experiments were conducted to study the effect of shear angle for blank has a diameter (50 mm) on shear force of a low carbon steel sheet (AISI 1008). Low carbon steel is a very common material used in fabrication of sheet metal components, with thickness of (0.5 mm). Tools used in the blanking tests were one traditional flat end punch and four different bevel sheared rooftop punches, which rooftop punches were compared to. and it (0°, 5°, 10°, 15°, 20°) a punches diameter (49.95 mm) by clearance (0.025mm) for each side , with a blanking speed (500mm/min). A special blanking die set is designed and manufactured and was a blank cut by a hydraulic press whose capacity (20 ton). The results showed that the blanking forces of (AISI 1008) low carbon steel metal could be decreased radically with best bevel punch geometry. Using (10°) shear angle at the punch end, the cutting forces decreased up to (90%) compared to the ones of the traditional flat end tool
Influence of Stirring Speed on Mechanical Properties for Cast Nano-Particulate AA7075-Al2O3 Composites
Aluminum metal matrix composites are widely employed for improving the mechanical properties. Various fabrication routes like liquid state, solid state and liquid-solid state are currently available for producing these materials. The objective of the present work is the fabrication of nano particulate composites AA7075-Al2O3 with different amount of nano particles (20-30 nm) reinforced material Al2O3 (2, 4 and 6 wt%) using stir casting technique at three stirring speeds (300, 850 and 1500 rpm). Tensile tests of these composites were carried-out to obtain the mechanical properties (ultimate strength and ductility). Vickers hardness tests were also performed to obtain the hardness number (VHN) of these materials. All tests were performed at room temperature. The microstructures of the best mechanical properties’ composites were examined for the three stirring speeds. It was revealed that the ultimate strength (?u) and Vickers hardness (VHN) for the composite containing 6 wt% Al2O3 fabricated at 850 rpm show the best properties compared to the other composites fabricated at 300 and 1500 rpm and the matrix. The ?u and VHN were increased by about (36.6 %) and (24.5 %) respectively. Ductility of the strongest composite (6 wt% Al2O3 at 850 rpm speed), however, was the least when compared to other composites and the matrix. With increasing the amount of Al2O3, ?u and VHN, an increasing trend was noticed while the ductility shows a reduction trend. The maximum reduction in ductility occurred for the composite containing 6 wt% Al2O3 obtained at 850 rpm. The ductility of the developed composite was reduced by (23 %). The optical microstructures of unreinforced, as-cast Aluminum alloy AA7075 and 6 wt% Al2O3 composites for all stirring speeds show dendrite microstructure resulting from the casting process, but the composite at the stirring speed of 850 rpm shows a more refined microstructure.
cast Aluminum nano particulate composites
Effect of Different Friction Stir Spot Welding Techniques on the Mechanical Properties and Microstructure of Aluminum AA2024-T3
This paper presents a comparison of using different techniques for stir spot welding of Aluminum 2024-T3, which are refill friction stir spot welding (RFSSW), edited (RFSSW-pin) and conventional friction stir spot welding (FSSW), depending on the obtained tensile shear strength property. Specimens were prepared from AA2024-T3 sheet for chemical analysis and mechanical tests. Workpieces were stir spot welded utilizing the above mentioned techniques at four rotational speeds (2000, 2500, 3000 and 4000 rpm) using tool pin diameters (5 and 7 mm) for conducting the tensile shear tests. The microhardness along the cross section of the welded specimens was conducted at the best conditions as well as the microstructure examination. The comparison results revealed that at the rotational speeds (2000 and 4000 rpm) in both cases of tool pin (5 and 7 mm), the ultimate tensile shear force was slightly higher than that for other speeds. However, the ultimate tensile shear force was found higher at 3000 rpm speed with a tool pin 7 mm. The microhardness results manifested a W-shape at the best conditions. Finally, the microstructure examination depicted the morphology of the main zones of the weld joint.
The Porosity Effect of Stainless Steel Balls on Forced Convection Pipe Flow
An experimental study has been carried out to investigate the effects of stainless-steel balls on forced convection flow in pipe under uniform heat flux. Water is used as the working fluid and stainless-steel balls as a porous media. The Reynolds number range from (5000 to 9000) based on the diameter of the pipe. The experiments were conducted on three various numbers of stainless-steel balls (N) with various diameters (dp), which give various porosity (0.33, 0.38 and 0.41). These are (N= 2400, dp=1mm), (N=1600, dp=3mm) and (N= 750, dp=5mm). Results show that, heat transfer coefficient increases with the decrease in the porosity due to the reduction in the space between balls. This led to an increase in turbulence and produced eddies. Furthermore, enhancement in heat transfer coefficient reached its maximum value of (45%) for ball diameter with (dp=1mm) and water flow rate (9 L/min). New Correlation equations for the average heat transfer coefficient were obtained for three different diameters of balls (1, 3 and 5 mm).
Evaluation of Moisture Susceptibility for Modified Open Graded Friction Course Mixes Used Styrene Butadiene Styrene
Open-graded-fraction-course (OGFC), is a hot asphalt mixture usually utilized as a private purpose wearing course, because of open graded asphalt mixture and aggregates skeleton (stone-on-stone) contact, it contain a relatively high air voids’ percentage, after compaction which are permeable to water. In this research one type of gradation was used (12.5 mm) NMAS, to preparing the OGFC asphalt mixtures, penetration grade 40/50, crushed aggregate, asphalt content prepared with 4 % and up to 6 % by weight of mixture with 0.5 % increments. Optimum asphalt content (OAC) was selected based on these criteria, air voids content, asphalt draindown, permeability, and abrasion resistance (aged and un-aged) condition. The mix performance had been investigated by indirect tensile strength and moisture susceptibility (sensitivity) measured according to the (AASHTO T283-14). Results illustrate that the increasing of asphalt binder content leads to a decrease of the air voids content, abrasion loss and permeability values, while draindown increase, conversely, the indirect tensile strength (ITS) had been significantly increased for both conditions and this is a gaod suggestion to resistance alongside moisture susceptibility. It can be decided that the increasing of asphalt binder percent in OGFC asphalt mixture, leads to an increase in the thickness of binder coating around the aggregates. On the other hand, the influence of modifier that prepared with 4% styrene-butadiene-styrene (SBS) on OGFC asphalt mixture tends to improve the mix properties and exhibit higher (TSR) as compared with original asphalt by (31, 27.7 and 24.4) % at asphalt percent (4.8, 5.3 and 5.8) %, respectively. The SBS improved the adhesion between aggregate and asphalt which leads to reduce stripping of HMA, horizontal deformation, and increased the tensile stiffness modulus value.
Indirect Tensaile Strength And Moisture Sensitivity
An An Analysis of Strain Rate Distribution Using Streamline Model and A Quick Stop Device in Metal Cutting
In this paper, a quick stop device technique and the streamline model were employed to study the chip formation in metal cutting. The behavior of chip deformation at the primary shear zone was described by this model. Orthogonal test of turning process over a workpiece of the 6061-T6 aluminum alloy at different cutting speeds was carried out. The results of the equivalent strain rate and cumulative plastic strain were used to describe the complexity of chip formation. Finite element analysis by ABAQUS/explicit package was also employed to verify the streamline model. Some behavior of formation and strain rate distribution differs from the experimental results, but the overall trend and maximum results are approximately close. In addition, the quick stop device technique is described in detail. Which could be used in other kinds of studies, such as the metallurgical observation.
Effect of Alumina (Al2O3) Particles on The Mechanical Properties of Magnesium (Mg)
In the present study, magnesium-based composites reinforced with different volume fractions (3, 5, 10, and 15) vol.% of micro sized Al2O3 particulates were fabricated by powder metallurgy technique which involves mixed, compacted and sintered. Powders were mixed by ball milling (without balls) for 6 hours at rotation speed 60 rpm. Then powder was compacted at 550 MPa and sintered at 530?C for 2 hours. Microstructures of sintered composites have been investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) energy dispersive. SEM image of sinter samples exhibit good bonding between the magnesium matrix and the alumina. The microhardness and wear resistance of micro composites has been improved significantly compared to that of pure magnesium. Highest value of microhardness is 97 HV at the volume fraction of 10 vol.% Al2O3.
Study the Effect of Using Microwave Energy in Chemical Processes for Dyeing and Printing Pretreatments of Cotton Fabrics
The research focuses on studying the effect of microwave energy as an alternative heating method on dyeing and printing pretreatments of cotton fabrics. In this research, a microwave oven was used to heat the solutions which used in de-sizing, scouring, bleaching and mercerizing processes at different energy levels. The results showed the importance of this heating method in improving desizing efficiency where the best result was obtained at 180 W and 24 min and this method was beneficial in saving energy and time. The best result in scouring was obtained at 720 watts and 24 minutes, whereas at 720 watts and 20 minutes was the best result in bleaching. We can save energy, time and chemicals compared with the conventional method. The mercerizing by microwave increased the absorption of dye solutions for the samples compared with the traditional method, where the color strength increased by increasing the treatment time and the level of energy in the microwave and the best result was obtained at 900 watts and 90 seconds.
Inducing Frictional Force to Enhance the Transient Response in Beams
This paper studies the effect of contact areas on the transient response of mechanical structures. Precisely, it investigates replacing the ordinary beam of a structure by two beams of half the thickness, which are joined by bolts. The response of these beams is controlled by adjusting the tightening of the connecting bolts and hence changing the magnitude of the induced frictional force between the two beams which affect the beams damping capacity._x000D_ A cantilever of two beams joined together by bolts has been investigated numerically and experimentally. The numerical analysis was performed using ANSYS-Workbench version 17.2. A good agreement between the numerical and experimental results has been obtained. In general, results showed that the two beams vibrate independently when the bolts were loosed and the structure stiffness is about 20 N/m and the damping ratio is about 0.008. With increasing the bolts tightening, the stiffness and the damping ratio of the structure were also increased till they reach their maximum values when the tightening force equals to 8330 N, where the structure now has stiffness equals to 88 N/m and the damping ratio is about 0.062. Beyond this force value, increasing the bolts tightening has no effect on stiffness of the structure while the damping ratio is decreased until it returned to 0.008 when the bolts tightening becomes immense and the beams behave as one beam of double thickness.
The Usage of Time Reverse Technology to Improve The BER Performance and Transmission Rate of IR-UWB System
Ultra-Wideband (UWB) technology has so many striking characteristics which includes low sensitivity to fading, superior performance, low interference, easy to penetrate in walls as well as in floor. The main motive of this work is to analyze the capability of UWB technology as various aspects and improve its performance, since the main drawback of this system is that the power spectral density of the transmitted signal is rather limited. The MIMO technology may provide a solution by increasing the received SNR for the same transmission power, but the problem in this case is the spatial correlation resulted. To solve the problem two technologies are integrated along with the UWB using Time Reverse (TR) by TR-MIMO and TR-SIMO. Among these integrations, the robust performance of the UWB is analyzed by comparing the transmission rates for a given outage probability. In the last step, the (SIMO/MIMO)-UWB and TR-(SIMO/MIMO)-UWB were compared in terms of BER values to create the way of applying the UWB in so many applications.
Preparation of Zinc Oxide Nano-Layer on Cotton Fabric for UV Protection Application
Zinc oxide nano particles is one of the best choices for ultraviolet protection due to its special properties. In this research, the UV-protection ability of sol gel-derived thin ZnO films on cotton fabrics was investigated. Various polymers have been used as adhesives to bind the nano-oxide with the surface of the treated fabric. Scanning electron microscopy and UV spectroscopy were carried out to study the properties of the treated fabrics. The results showed that the diameters of the synthesis zinc oxide particles - (68.81, 41.76 and 44.6 nm) with (PVA, PVP and CMC) respectively- were of the nanostructure, and the smallest diameter of the particles was produced with polyvinylpyrrolidone as adhesive. Using a spectrophotometer showed a decrease in the transmittance of the studied samples compared with the raw untreated sample of about 23%.
Spatial Modification in the Parameters of Mountain Image Clustering Algorithm
Our proposed method used to overcome the drawbacks of computing values parameters in the mountain algorithm to image clustering. All existing clustering algorithms are required values of parameters to starting the clustering process such as these algorithms have a big problem in computing parameters. One of the famous clustering is a mountain algorithm that gives expected number of clusters, we presented in this paper a new modification of mountain clustering called Spatial Modification in the Parameters of Mountain Image Clustering Algorithm. This modification in the spatial information of image by taking a window mask for each center pixel value to compute distance between pixel and neighborhood for estimation the values of parameters ?, ? that gives a potential optimum number of clusters requiring in image segmentation process. Our experiments show ability the proposed algorithm in image brain segmentation with a quality in the large data sets
Built Heritage Attractions in Cultural Tourism: the case of Al - Mustansiriya Madrassa, Baghdad
This research deals with the subject of Built heritage attractions in Muslim historical building, for what it represents, as an element dealing with Cultural tourism, in the process of developing tourism industry of the city._x000D_ The location of Mustansiriya Madrassa in Baghdad’s commercial district could make it a profitable investment project to revive a cultural, artistic and tourist centre that could make it a cultural Tourism haven._x000D_ The problem emerges through, how the role of built heritage to attract tourists in order to give vitality and liveability to the cultural tourism destination such as Al - Mustansiriya Madrassa which is one of the most popular heritage destinations, a historic school building situated in the ancient Abbasid district of Rusafa in the very heart of Baghdad._x000D_ Therefore, the research's aim is to shed light on the heritage attraction as a mean to clarify the meaning of Cultural Tourism and specifying its definition._x000D_ This research explains how the built heritage plays an important role in tourism in general and in the cultural tourism in particular because they attract tourists and provides a sustainable economic resource through its inclusion of values that make it distinct from other sources of attraction.
Effectiveness of Glass Wastes as Powder on Some Hardened Properties of Concrete
This paper present glass waste material reusing in concrete as partial replacement of cement. Some hardened properties like compressive and flexural strengths, modulus of elasticity and % absorption was made. The effect of glass powder on these properties was examined compared to reference specimens without glass powder. Five percentage was tested: 0%(reference), 10%, 15%, 20% and 25%. From tests results one can conclude that replacing cement partially by glass powder enhanced strengths of concrete (compression and flexural) up to 20% replacing level Using glass powder as partial replacement of cement improved strengths and modulus of elasticity of concrete. The %absorption decrease with increasing of glass powder content. The results show that utilization of waste glass as powder in concrete can reduce amount of cement which save cost besides its environmental benefits.
Comparative Studied of Degradation of Textile Brilliant Reactive Red Dye Using H2O2, TiO2, UV and Sunlight
In this study sunlight and UV radiation were used to compare the efficiency of decolorization of textile wastewater containing brilliant reactive red dye K-2BP (?max = 534 nm) by the advanced oxidation process (AOP) using (H2O2/sunlight, H2O2/UV, H2O2/TiO2/sunlight, and H2O2/TiO2/UV). The results studied the effect of solution pH, applied H2O2 concentration, TiO2 concentration (nanoparticle), and initial dye concentration were studied. The experimental results showed that decolorization percentage with H2O2/sunlight and TiO2/H2O2/sunlight under the following conditions: - reaction time 150 of minutes, [ 500 ppm] H2O2, [100 ppm] TiO2, pH=3, initial dye concentration =15 ppm and at ambient temperature were 95.7% and 98.42% respectively. For the same conditions using H2O2/UV, H2O2/TiO2 /UV, the percentage of decolorization were 97.85% and 96.33% respectively. The results also indicated that the sunlight is more economic and cost-effective than UV radiation.
Performance Enhancement of Photovoltaic Panel Using Double-sides Water Glazing Chambers Cooling Technique
The efficiency of the solar PV panel decreases significantly as the PV panel’s operating temperature increases. There are many cooling techniques might be suitably deal with this problem to enhance the solar panel efficiency. The presented cooling technique used for solving the PV panel’s temperature elevation is an active close loop cooling system, accomplished using two water glazing chambers made from acrylic glass placed at the PV panel surfaces (rear and front). These champers are utilized for cooling down the PV cell’s temperature, as well as filtering the useful sunlight spectrum. The results show that the PV cell’s temperature reduction by 50.06% with using the cooling system, this leads to an average increase in the maximum output power and consequently electrical efficiency of the PV panel by about 12.69% and 14.2%, respectively.
Enhancement of Heat Transfer using Aluminum Oxide Nanofluid on Smooth and Finned Surfaces with COMSOL Multiphysics Simulation in Turbulent Flow
Both surface extension and nanofluid methods were used to enhance the heat transfer in a double pipe heat exchanger under turbulent flow conditions. Aluminum oxide nanoparticles were used with different concentrations(0.6-3 g/l)in hot water to increase the heat transfer rate on smooth tube and circular fins tube for a range of Reynolds number4240-19790. The simulation was also performed to predict the heat transfer coefficient and temperature profile for selected conditions in which COMSOL Multiphysics is used. The experimental results revealed that the heat transfer enhancement by both circular fin and nanofluid exhibited an increasing trend with Reynolds number and nanofluid concentration. The conjoint effect of Al2O3 of 3 g/l concentration and circular fin provided largest heat transfer enhancement of 53% for the highest Re investigated. Simulation results showed reasonable agreement with the experimental values of heat transfer coefficient. The simulation showed that the presence of nanofluid on finned surface influenced the temperature profile indicating the increased heat transfer rate.
Improving the Mechanical Properties of Fiber Metal Laminate Composite Used in Aircraft Wing
The purpose of this study is to reduce weight and improve the mechanical properties of aircraft wing using Hybrid materials known as fiber metal laminates (FMLs). In this study, seven layers were used to produce the FMLs that consist of aluminum alloy2024-T3 reinforced by carbon and glass fibers bonded with blend of epoxy-resole. The Carbon Glass Reinforced Aluminum Laminates (CAGRALLs) was used as FMLs. The results showed that The CAGRALLs gave good mechanical properties because of increasing in tensile strength, elongation at fracture and impact toughness except flexural strength by comparing with other FMLs using commercial epoxy. The increasing in layers led to weaken adhesion force between layers of FMLs caused decreasing almost mechanical properties. The FMLs has good mechanical properties by using carbon and glass fibers by comparing with carbon and jute fibers. The CAGRALLs have higher numbers of cycles at failure under cyclic loadings than Aramid Reinforced Aluminum Laminates (ARALLs). The CAGRALLs have lower density by comparing with aluminum alloy 2024-T3 that used in manufacturing of aircraft wing.
Dynamic Modeling of Three Links Robot Manipulator (Open Chain) with Spherical Wrist
Dynamic modeling of a robot manipulator is a central problem in an accurate robot control. In this paper; the dynamic equations of motion were derived by using Eular-Lagrange method for a six degree of freedom articulated robot manipulator based on the geometrical jacobian construction for each link and actuator. In addition, friction effects beside the end effector forces that act the environment are considered. A Matlab Simulink plant is developed to embrace the theoretical work and simulate the dynamic response for a designed nonlinear controller Proportional Derivative plus Gravity (PD+G), also a modified controller is applied to reject the disturbances and the internal friction effect where the settling errors were 3.57E-6, 2.09E-7, -3.63E-6, 8.84E-6, -5.39E-8 and -4.39E-5 (deg) for joints one to six respectively. The presented approach can be applicable to solve the dynamic problem of other n-link robot manipulators and achieve a suitable solution for tracking trajectories.
Study the Impact of Quality Management System ISO 9001on Machinery Breakdowns
This research focuses on studying the importance of quality management system ISO 9001: 2015 and its impact on machinery breakdowns in the general company for the manufacture of wool and carpets in Hama for reducing the machines stops and thus increasing production quantities in the company. We did a field study in the company which a random sample of workers was interviewed in, taking into consideration the characteristics of the categories of workers.We analyzedthe dataobtainedfromthe workersby usingstatistical analysis program (SPSS19).The statistical results have shown that there is a strong correlation between the quality management system ISO 9001: 2015 and machinery breakdowns, which necessitates giving greater attention to the ISO 9001standard by the company's management and seeking ISO 9001 certification to achieve high performance for the company under study.
Copyright (c) 2018 Al-Nahrain Journal for Engineering Sciences
Assessment Mixing and Compaction Temperatures for Modified HMA Using Superpave High Shear Viscosity Methods
The objective of this study is determining the mixing and compaction temperature of the modified asphalt mixture. Results of binder tests showed that the addition of 3% SBS to control asphalt (PG 64-16) would achieve the desired performance level (PG 76-16) a performance grade that fits our climate with traffic loads. When using 5% SBS the performance grade of binder increased three grades (PG 82-16) and when increasing SBS content to 8% the performance grade increased four grades (PG 88-16). At shear rate of 500 (s-1), the modified asphalt viscosity can be obtained at different temperatures and the viscosity temperature curve can be achieved. As a result, the mixing and compaction temperature of modified asphalt can be determined to reach 0.17 ± 0.02 Pa.s and 0.28 ± 0.03 Pa.s for mixing and compaction, respectively. It is noted that SBS modified reached a viscosity of 3 Pa.s when 8 % additive. Additive contents above these values may not be suitable for good workability and pump ability according to Superpave specifications. While addition of 5% SBS with control asphalt, more than 3.7times at 135°C Increase the viscosity. Marshall Stability test indicated that the strength for the SBS specimens increases as compared to the conventional specimens. An increase of about 39%, 74%, 102%, was observed with 3%SBS 5%SBS 8%SBS modified binders, respectively. The Marshall test results for 8%SBS binders required compaction temperatures above 175°C need to keep up quality of HMA item while limiting natural effect amid development, these proposals are unsatisfactory Modified mixtures the 5% SBS modification was determined to be the maximum useful content. The Superpave method to estimate mixing and compaction temperatures show are not practical for use with modified binders. Also, it is observed that good agreement values between the average Marshall compaction temperature and the High Shear Viscosity Method (HSRV) and lower than Superpave methods Where the decline ranges from 15 ºC to 17 ºC.
Liquid Nitriding of Stainless Steel 316L to improve fatigue properties for Orthopedic Screws
Liquid nitrate is an important method used to improve mechanical properties. One of these properties is resistance to fatigue. The aim of this study was to improve the fatigue resistance of the stainless steel 316L. The rotational bending method was used with constant and variable stresses at different times of (1, 3, 5) hours and at (530, 630) C0. These tests were performed before and after nitration._x000D_ The results showed that the depth of the nitride layer was (0.21, 0.33, 0.45) mm, increasing with time nitriding when the temperature was 530 C0. While the depth of this layer at a temperature of 630 C0 (0.26, 0.39,0.5) mm with increasing time. As a result of these processes, a layer of solid chromium nitrides and other phases of iron nitride were formed on the outer surface. These layers helped to inhibit the growth of the cracks and their progress in addition to the generation of pressure stresses on the surface leading to obstructing the progress of the cracks._x000D_ This study showed that the fatigue resistance was directly proportional to the increase in nitrate time due to the increased depth of the hardened layer, but this resistance decreased when the temperature was 630 C0 due to the formation of brittle phase with low resistance.
A Combined H2/Sliding Mode Controller Design for a TORA System
In this work, the control of Translational Oscillations with a Rotational Actuator (TORA) system is presented in this paper. The optimal sliding mode controller is proposed to control the two DOF underactuated mechanical system. The nonlinear coupling from the rotational to the translational motion is the main problem that faces the controller design. The H2 sliding mode controller is designed to give a better performance if only sliding mode control is used. The results illustrate that the proposed H2 sliding mode controller can achieve the stabilization of the system with the variation in system parameters and disturbance.
Performance Study of Solar Adsorption Refrigeration System Using Activated Carbon - Methanol
The depleting of the conventional sources of energy and the excess use of HCF components lead to the need for new techniques both for conservation of energy sources for the future and for decreasing the its harmful effects on the environment. This study investigated the adsorption capabilities of activated carbon. The adsorption of methanol on this substance was tested for their application in the adsorption refrigeration system based on solar energy._x000D_ Adsorption refrigeration system has been designed and manufactured with the energy source being solar energy. Methanol/activated carbon pairs have been used in experiments. The present work focused on the performance of the adsorption refrigeration system considering the temperature attained in the evaporator and the cooled spaced cabinet. The amounts of activated carbon used was (8 kg), while the amount of methanol were (1, 1.25, and 1.5) kg. The experiments were done in different days of the year. The amount of adsorption of methanol (as a result of decreasing the evaporator and cooled spaced temperature) was found to depend on the generator pressure and its increase as the primary generator pressure decreases. The best mass of methanol used was (1 kg) which give the lowest temperature obtained at the evaporative surface was ( 3.4 oC ) at the day ( 4/4/2017 ). The results shown that even in cloudy days there is a benefit from using such a system because the temperature attained is enough to start the adsorption process. The lowest temperature obtained at the evaporative surface was (3.4 oC) at the day (4/4/2017) for methanol mass of (1 kg) at an opening time of the valve between the evaporator and the generator (9:30am). The increase of methanol amount used in the experiment led to a good decrease in temperature attained in cooled spaced, but this is related to the time of connecting the evaporator and generator.
Output Feedback Adaptive Sliding Mode Control Design for a Plate Heat Exchanger
The heat exchanger is a device used to transfer heat energy between two fluids, hot and cold. In this work, an output feedback adaptive sliding mode controller is designed to control the temperature of the outlet cold water for plate heat exchanger. The discontinuous gain value of the sliding mode controller is adapted according to a certain adaptation law, where the only information required is the measurement of the outlet cold temperature. A sliding mode differentiator was design to estimate time derivative of outlet hot water temperature. Two constraints which imposed on the volumetric flow rate of the hot water (control input) were considered within the rules of the proposed adaptation law in this work. These are the control input is positive only and has a maximum value. For constructing the sliding variable, the outlet hot water temperature and its time derivative are required. The maximum allowable desired outlet cold water has been estimated as function of heat exchanger parameters and maximum control input. The simulation results demonstrate the performance of the proposed adaptive sliding mode control where the outlet cold water was forced to follow desired temperature equal to . Additionally, the robustness of the proposed controller was tested for the case where the cold inlet temperature is not constant. The results reveal the robustness of the proposed controller.
Study the Effect of Using Different Bearing Types on the Performance of Evaporative Cooler
An investigation of performance response of two types of bearings such as Cylindrical Roller Bearing and bush bearing on evaporative cooler driven by DC motor of 1500 r.p.m, through studying many parameters like vibration response, temperature raise, humidity, sound level and total performance. high quality 3D positions X, Y and Z, vibration sensors type (ADXL335 accelerometers) with Arduino mega 2560 that interfaced with Lab-View program were used to measure changes in vibration amplitude and frequency. Two temperature sensors of type (LM35) were used to investigate the temperature raise in the bearings also with Arduino mega 2560 that interfaced with Lab-View program. For humidity a sensor of type DHT22 was used, also, a portable device was used to measure electricity consumption, rotary speed and sound level in the bearings of evaporative cooler. By replacing bearings all the parameters above wear measured then a comparison between them were made to find the best performance and operation of these bearings. The obtained results from the experimental work have clarified and explained by tables and figures. It has been found that the vibration of evaporative cooler in X, Y and Z-directions increased by using two cylindrical roller bearings than using two of bush bearings. The temperature of cylindrical roller bearings increased When running the evaporative cooler more than bush bearings. the noise of Evaporative Cooler by using both types of Bearings was almost same but with a little Reduce by using cylindrical roller Bearings. Which means the Evaporative Cooler has better Performance by using bush bearings than using cylindrical roller bearings.
Gait Analysis after Unilateral Total Hip Replacement Surgery
Total hip replacement (THR) is an elective surgical procedure with the primary indication being pain relief. The aim of this study is to analyze gait dynamics for patients after they underwent a unilateral THR surgery and compare it with normal parameters. To investigate the gait dynamics a gait analysis was performed on five patients after they underwent a unilateral THR surgery; only two of them were examined before the surgery. The gait analysis was performed using a digital video camera with two force plates. Kinematics data were obtained from 2D trajectories of seven passive markers using SkillSpector software. MATLAB software has been used for inverse dynamics computation. General gait parameters, Harris Hip Score, joints’ angles, forces, moments and powers were obtained during gait cycle. It was found that the average of improvement in Harris Hip Score (for four patients who were examined 1.5, 2.5, 3 and 9 months after surgery) is 61.8 points, which is an indication of pain relief. In the other hand, the general gait parameters were found slightly lower than normal after THR surgery. The average hip reaction force was found to be 2.988 N/BW, which is within normal range. Also, the average of maximum hip extension and maximum hip flexion angles were found to be 25.69 and -13.524 degree respectively, which both are within normal ranges. Furthermore, hip, knee and ankle moments and powers results showed some abnormality. Therefore as a conclusion, patient satisfaction and functional improvement are not related to general gait parameter. And it is not unusual that gait mechanics improvement would not reach normal after months of recovery. Also, the results of gait dynamics which are from the engineer’s perspective are compatible with Harris Hip Score, which is from the physician’s perspective, in quantifying surgical results and subsequent recovery progress.
Effect of Agitation, Temperature, and Quenching Medium on Cooling Curve and cooling rate for Steels
The control of quenching process has been investigated in this study by developing a quench system design to simulate the quenching process and measure the time – temperature history inside the sample during the cooling stage. The main purpose of this quench system is to evaluate the quench power of different quenchant at different conditions (type, temperature and agitation).A stainless steel sample was used with a suitable measurement as a probe in designing this quench system.The performance of two of quenchants (water and brine) with different conditions was investigated, and the designed probe was used to illustrate the effect of quenching parameters (quenchant type, temperature and its agitation) on cooling curves and cooling rate.The quenching system has proven its ability to work effectively and the results showed that heat transfer properties were significantly affected by quenchant parameters.
A Study of Diffusion Phenomenon in Friction Stir Lap Welding Joints for Low Carbon Steel C10 to Aluminum Alloy AA1100-H112
In this study the friction stir lap welding was carried out by a new technique (diffusion bonding phenomenon) between (AA1100 and low carbon steel C10 sheets of 3mm and 1mm thickness respectively. These alloys have difference ranges in melting temperature and other physical properties. Different parameters were used: tool rotation speeds (630, 1250) rpm, travel speeds (80, 32) mm/min. and pin length (2.8,3) mm using cylindrical threaded pin. Many tests and inspections were performed such as tensile shear test and X-Ray diffraction tests. Microhardness and microstructure observations were conducted by using optical and SEM. The above tests were used to evaluate the weld quality and joint efficiency under different welding parameters. Best result for FSLW by diffusion phenomenon appear in (low carbon steelC10 / AA1100-H112) joint at 1250rpm in 32 mm/min. with 2.8mm pin length and the maximum tensile shear strength was (3.9)KN.It was found that the highest micro hardness was (138HV) at the interface between the low carbon steel and AA1100.