Non-typical Hazards in Road Traffic

The authors describe a road traffic accident with an unusual cause which was a wrong defensive reaction of the driver on the road surface covered with spilled grain. The results of road tests are presented illustrating behaviour of the vehicle on the road surface in such conditions. Attention is paid to the psychological aspect of the drivers defensive reactions in the situation when they are taken aback with non-typical road surface conditions. There is a need to train drivers in right decision making skills (psychology) and in the ability to make effective defensive manoeuvres (driving technique) in order to improve road traffic safety.

Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/

Comparison of Different Simulation Approaches in Ring-Core Method

Ring-Core, a semi-destructive method enables measurement of the residual stresses inside the material by the sensor attached at the top of the specimen. Such stress reconstruction requires proper determination of the calculation coefficients. Thus the simulation model for finite elements analyzes is created by means of two different commercial software. Subsequently both simulation results are compared experimentally by measurement on the specimen loaded by known uniaxial state of stress.

Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/

Time Structure Optimization of Logistics Chain during Assembly

Assembly operations as a basic unit crucially affect the productivity and overall efficiency of the entire production and assembly process. To increase the productivity of the entire production-assembly process is necessary to analyze the individual steps of assembly cycle, eventually find a solution that would be optimal and was used the gradual, concurrent or combined form of production-assembly process.

The first level creates a conceptual model implementing the assembly process. Indicates the principle of assembly solutions and determines the sequence of the production-assembly phases. It is therefore appropriate at this phase to create several structures (sub-assemblies) in order to clear the sequence and continuity of assembly steps. Assembly of guard portion is characterized by concurrent form of assembly process. Parts and assemblies going from department Pn to department Pn+1, and the total time of protector assembly cycle takes about 5.4 min/unit (one worker).

Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/

Modal Analysis of Axially Symmetric Structure

Currently, modal analysis as a tool for investigation of vibration becomes an important part of designer work. Whether it is necessary to perform determination of modal parameters, analyze amplitudes of vibration [1, 2], verify the numerical model experimentally [3, 4] or express the influence of different parameters on the vibration [5, 6], the knowledge of dynamic behavior of structures plays an important role as they are designed.

Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/

Effect of Dynamic Absorber Configuration on the Reduction of Vibration

The methodology how to design such a system is explained in the paper. The first type of dynamic absorber is composed by two masses connected to the seat by springs and dampers in parallel configuration. The second one is composed by two sprung masses connected to the seat in the series. The parameters of the seat suspension system and the dynamic absorber parameters were all determined by an optimization process based on genetic algorithms. The objective function for the optimization was to minimize the seats displacements. The vibration reduction of the seat is compared for both investigated cases.

Website:  http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/

Acceptance and Re-verification Test of Length Metroscope

Paper deals with acceptance and re-verification of length measuring metroscope. The metroscope has been used very frequently for exercises in subject – Engineering Metrology at the bachelor study. New systematic errors have been obtained from calibration process. Other measurements have been also realized and corrections of results have been executed via using of new systematic errors. Measured errors from acceptance test have confirmed that metroscope is out of the limits defined through the maximum permissible error. Nevertheless the metroscope is fully functional and errors could be eliminated through the including of new measuring system consisting from suitable distance sensor.

Website:  http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/

Comprehensive Approach to Technical Conditions of Electromechanical Units in Mechatronic Systems

Analysis of mechanical and electrical diagnostic parameters of electromechanical units is considered as an integrated approach. The relationship between mechanical, electric diagnostic parameters and technical conditions of the electric drive is investigated on the example of the stand consisting of the asynchronous motor, the coupling and a worm gear. The most sensitive diagnostic parameters were identified in case of various defects in electromechanical units. The change in the spectrum of vibration of the motor and the coefficients of the wavelet analysis of the electric current of the motor stator were investigated at idle and under load, in the absence and presence of the following defects: a decrease in the contact patch gear, misalignment coupling rims, as well as grazing rotor motor.

Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/

Lateral Rotor Vibration Analysis Model

 Rotor dynamics is the branch of engineering that studies the lateral and torsional vibrations of rotating shaft, with the objective of predictive the rotor vibrations and containing the vibration level under an acceptable limit. Lateral rotor vibration (LRV) is radial-plane orbital motion of the rotor spin axis. Transverse rotor vibration is used synonymously for LRV. Actual LRV orbits are typical only a few hundredths of a millimeter. LRV is an important design consideration in many types of rotating machinery, particularly turboelectrical machines such as steam and combustion gas turbine/generator sets, compressors, pump, gas turbine jet engines, turbochargers and electric motors. Thus LRV affect several major industries. Usually, but not always, the potential for rotor dynamic beam-bending-type deflection significantly contributes to the LRV characteristics. The significance of LRV rotor bending increases with bearing-to-rotor stiffness ratio and with rotor spin speed. Consequently, in some rotating machines with a low operating speed and /or low bearing-to-rotor stiffness ratio, the LRV is essentially of a rigid rotor vibrating in flexible bearing or support. The opposite case (a flexible rotor in essentially rigid bearings) is also possible but rotor dynamically less desirable, because it lacks some vibratory motion at the bearings which often provides that essential ingredients, damping, to keep vibration amplitudes at resonance conditions within tolerable levels. A rotor’s flexibility and mass distributions and it is bearings flexibilities combined with its maximum spin speed essentially determine whether or not residual rotor unbalance can produce forced LRV resonance. That is these factors determine whether the rotor-bearing system has one or more lateral natural frequency modes below the operating speed.

Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/

Tecnomatix Plant Simulation, Its Features and Its Integration into Business Processes in Logistics Systems

The trend at the moment, but also over the past decades are Information Technologies. Through these technologies companies nowadays govern their production, as well as administrative processes. Without them, existence of even one enterprise was today not possible, whether large or small. In business practice several types of tools are used from ranks of information technologies. The most basic tools are for controlling administration. Among more complex are those which are already used to a partial or full management of production in certain positions, or entire production halls. Among the most complex we can include means to verify the process of planning future work practices. Planning and assessing future status of planned production by those means and subsequently they can be applied in the process of governance of real production.

Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/

Proposed Model of Hand for Designing Ergonomic Vibration Isolation Systems for Hand-held Impact Tools

An operator’s hand model is proposed comprising uniform bars positioned at angles adequate to the working position of the upper extremity during soil compacting operation. The model is addressing both the subject operator’s anthropometric traits and the tool’s interaction with the system. Model testing data of the hand-arm system are in good agreement with the results of experimental testing, in which the level of accelerations measured both at the tool handle and at the most exposed areas of the hand, that is at the wrist and at the elbow, were determined using miniature triaxial vibration sensors. The presented hand-arm system model makes it possible to analyze interaction between the hand and the tool and transmission of vibration from the tool to the human body. The proposed methodology may be used in creating ergonomic working environments and in designing safe impact tools.

Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/

Analysis of potential flow around two-dimensional body by finite element method

The numerical technique is based upon a general formulation for the Laplace’s equation using Galerkin technique finite element approach. The solution of the systems of algebraic equations is approached by Gaussian elimination scheme. Laplace’s equation is expressed in terms of both steam function and velocity potential formulation. A finite element program is developed in order to analyze the result. The contours of stream and velocity potential function are drawn. The contour of stream function exhibits the characteristics of potential flow and does not intersect each other. The calculated pressure co-efficient shows the pressure decreasing around the forwarded face from the initial total pressure at the stagnation point and reaching a minimum pressure at the top of the cylinder.

Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/

Dynamic analysis of the influence of fiber orientation in composite laminated plates

The behavior of the material is modeled through finite element method, where the First Order Shear Deformation Theory (FSDT) is used which is implemented on a rectangular element serendipity containing eight nodes. The mathematical modeling has been implemented using the commercial available software MATLAB®. Through numerical simulations, it will be possible to obtain the natural frequencies. And we will present a sensitivity analysis with respect to the fiber orientation parameter.

Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/

Effects of fuel injection discharge curve and injection pressure on upgrading power and combustion parameters in heavy-duty (HD) diesel engine with computational fluid dynamics (CFD) simulation

 Hence, the fuel injection discharge curve is changed from semi-triangular to rectangular which is usual in common rail fuel injection system. Injection pressure with respect to amount of injected fuel and nozzle hole diameter are changed. Injection pressure is calculated by an experimental equation which is developed for heavy duty diesel engines with common rail fuel injection system. Power upgrade for 1000 and 2000 bar injection pressures are discussed. For 1000 bar injection pressure with 188 mg injected fuel and 3 mm nozzle hole diameter, power is upgraded about 19% in comparison to original state which is semi-triangular discharge curve with 139 mg injected fuel and 3 mm nozzle hole diameter, with no special change in cylinder pressure. On the other hand, both the NOX and the Soot emissions decreased about 30 and 6%, respectively. Compared with the original state, in the case of 2000 bar injection pressure, with injected fuel and nozzle diameter, 196 mg and 2.6 mm respectively, the power is upgraded about 22%, whereas cylinder pressure has been fixed, and the NOX and the Soot emissions are decreased to 36 and 20%, respectively.

Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/

Establishment of an air quality monitoring model for dust-free rooms using neural network and control chart techniques

Accuracy ventilation in dust-free room is related to the experimental results, proper ventilation can help reduce levels of pollution particles inside the laboratory. In addition to particle pollution exclusion, the pollution particles into the switch through the door, whether we can be inhibited by different ventilation position pollution particles into the lab, then laboratory ventilation should be a priority. Laboratory common sources of pollution, tiny particles such as micro-electromechanical laboratory processes generated by the air conditioning ventilation equipment into dust, biological experiments may leak off bacteria, these contaminated dust particles and bacteria accumulate even off the air in the operating environment, some will direct the human body after inhalation injury, and can cause damage and affect the accuracy of the experimental laboratory equipment.

Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/

Optimal maintenance scheduling of thermal power unıts in a restructured nigerian power system

It uses HPSO algorithm to find the optimum schedule. The purpose of the algorithm is to orderly encourage moving maintenance outages from periods of low reliability to periods of high reliability, so that a reasonable reliability level is attained throughout the the year. The maintenance outages for the generating units were scheduled to minimize the sum of the squares of reserves and satisfy 2,943.8 MW system peak load with 6.5% spinning reserve of 2,403.8 MW, available manpower for maintenance per week of 22 and maximum generation of 3,028.8 MW. The reliability criterion of the power system was achieved by maximizing the minimum net reserves along with satisfaction of maintenance window, crew and load constraints. The population size of 30 particles and 2500 iterations were chosen. These were chosen as a trade-off between computational time and complexity. It was shown that the HPSO algorithm is not as time efficient as the standard PSO but it provides more consistent and reliable results. In the periods of low maintenance activities, with the PSO algorithm, the maximum generation is 2,753.8 MW while the HPSO produce 2,943.8 MW. It is glaring from the comparison that the HPSO algorithm shows better performance and produce optimal maintenance scheduling framework for the Nigerian power system that will achieve better utilization of available energy with improved reliability and reduction in energy cost.

Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/

Mass Reduction of Involute Spur Gear under Static Loading

Gears are one of the most basic components of any machine or mechanism since few centuries. Gears have wide variety of applications but they are commonly used for transmission systems. Gearing is the most critical component in a mechanical power transmission system and industrial machineries. As there are so many merits of the gears, it also has some limitations i.e. weight & Size. The weight of gear makes it difficult to use gears for compact and light duty applications. In this study some geometrical features have been incorporated in the spur gear to optimize the weight and to know its effect on the development of stresses. A finite element model of spur gear is considered for the study and static stress analysis is carried out using ANSYS 14.5.

Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/

Comparison Between Triangulation and Curve Fitting Tool Methods for Underwater Ranging Using Stereo Vision

There is a growing interest in underwater applications. Stereo vision is one of the best methods for distance estimation of underwater object. In this research two pairs of cameras were used as stereo image acquisition to estimate the distance of underwater object. The stereo vision system in this project consists of calibration of camera, rectification of images, segmentation of images, finding of centroid and localization of object. Edge-based segmentation, Mathematical morphology and largest area selection are used to perform image segmentation. Finally, It will be shown that curve fitting is better than triangulation method to estimate the coordinates with the overall error of around 0.5 cm with water condition where the overall error of using triangulation method is around 2.2 cm which is too much in range estimation

Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/

Aerodynamic Study of Small Scale Vertical Axis Wind Turbine System in Urban Circumstance

The VAWT (vertical axis wind turbine) has advantages over HAWT (horizontal axis wind turbine) that it allows less chance to be degraded independent of wind direction and turbine can be operated even at the low wind speed. However, VAWT in urban area generally has weak and turbulent wind conditions due to the presence of high-rise building. Therefore, VAWT operation under both stalled and unstalled conditions with various effective angles of attack are also in the presence of dynamic stall which are particularly significant impact on load and power the operation at low tip-speed ratio. The objective of this study is to analyze aerodynamics of the VAWT blade and investigate the ideal shape of blade. The analysis of aerodynamic characteristics with various blades has been performed using numerical simulation with CFD software. As the numerical simulation discloses local physical features around wind turbine, aerodynamic performance such as lift, drag and torque are computed for single blade rotation and multiple blade rotation cases. Through this study, an accurate aerodynamic physic is defined, furthermore, effective blade shape is suggested based vortex-blade interaction studies.

Website: http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/

Performances Improvement of Solar Stills by Reflector External

The solar cascade still performance is investigated by computer simulation in terms of cascade stills efficiency and specific boiling times. Numerical calculations have been carried out for different tilts angle of the outer reflector on typical day (02-out) in East Algeria (Constantine). To do this work, one has to adopt a theoretical approach who consists in simulating this behavior by a computer program using a mathematical model where all the parameters characterizing the performance of the system are evaluated instantaneously during the period of sunning, Temperature of each element of distiller, thermal efficiency.

Website:  http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/

Experimental Parametric Study of Steel Joints between I Beams and Tubular Columns with a Reverse Channel

The main purpose of the investigation presented is the characterization of the nonlinear 

dynamic behavior of steel joints between I profile beams and hollow section columns with welded reverse channel. The experimental program supporting this investigation consists on the determination of the characteristics of the nonlinear cyclic behavior of the connection between I profile beams and circular or rectangular hollow section columns. The main goal of this research program is the identification and characterization of the connection components that control the hysteretic behavior of the connections to be used in seismic areas. The paper presents preliminary test results.

Website:  http://www.arjonline.org/engineering/american-research-journal-of-mechanical-and-automation-engineering/