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Universal Journal of Mechanical Engineering
Number of Followers: 16  Open Access journalISSN (Print) 2332-3353 - ISSN (Online) 2332-3361 Published by Horizon Research Publishing  [54 journals]
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- Expansion of Wave Rays and Fronts in Media with Inhomogeneous Structure
Abstract: Publication date: Sep 2018
Source:Universal Journal of Mechanical Engineering Volume 6 Number 4 Anatoli Chigarev and Ju. Chigarev In the article on the principles of Fermet, Huygens obtaine the differential equations in the form of Hamilton, which describe the ray trajectories and wave fronts in inhomogeneous media. Established that the vector of Poynting-Umov's determining the direction of energy propagation in inhomogeneous medium is coincident with the vector tangent to the ray. In the second part of the article established that the equations of the theory of rays' propagation in inhomogeneous media have the form of equations of nonlinear dynamics and describe the emergence of deterministic chaos in the geometry of rays for a wide variety of types of heterogeneous structures. In this case, the rays behave randomly and their description you must go to the description based on the theory of random functions and fields. In the third part of the paper is considered a model which is equivalent to the random medium and the calculation of the coordinates of the ray (the mathematical expectation and correlation functions). Understanding of these characteristics gives information about the behavior of the trajectories of the rays for these models of media. The description of the behavior of rays on the basis of the equations of statistical mechanics is discussed in the article for functions of Markov's type.
PubDate: Sep 2018
- Experimental and Numerical Study of Heat Transfer Process of Chilled Water
Storage Tank
Abstract: Publication date: Sep 2018
Source:Universal Journal of Mechanical Engineering Volume 6 Number 4 Firas M. Hasan and Maathe Abdulwahed Theeb Cool thermal energy storage using thermal stratification becomes one of the widespread applications because of the ability to shift the electrical cooling loads from on-peak to off-peak periods and significantly contributes to reducing the capacity of the refrigeration system and operating costs. Seven flow rate tests varying from 1.5 to 7.5 l/min for charging cycle were performed on small-scale vertical cylindrical storage tank equipped with three primary inlet diffusers, an elbow, two-ring linear and radial circular diffusers. The storage tank with inlet diffusers was assessed using temperature distributions and performance measures including thermocline thickness(ht), the half-cycle figure of merit (
) and equivalent lost tank height (ELH). Commercial finite volume code was used to predict temperature distributions in a stratified water tank model, temperature data acquired from experimental tests and simulation models were compared for validation purpose. The results suggested that the storage tank with two-ring linear circular diffuser produced better performance and higher stratification than two-ring radial circular diffuser for various flow rates by 1.4% , 20.6% ELH and 10.6% ht, and much better than an elbow diffuser by 1.7% , 24% ELH and 31.1% ht, furthermore, the degree of mixing was affected essentially the flow velocity which in turn causes an increase or decrease in thermocline thickness. Temperature distributions obtained from finite volume model are found to be in very close agreement with those obtained experimentally.
PubDate: Sep 2018
- Numerical Study of the Heat Transfer Rate of Nano-fluid Flow in a Channel
with a Triangular Cross-section in the Presence of a Magnetic Field
Abstract: Publication date: Sep 2018
Source:Universal Journal of Mechanical Engineering Volume 6 Number 4 Amir Haghighatkhah Hossein Ahmadi-Danesh-Ashtiani and Kourosh Amiraslani In this study, nanofluid flow inside a triangular channel in the presence of a magnetic field with two phase model was analyzed. For this purpose, the external surface of the channel is heated or cooled with a specific heat transfer coefficient, and the effect of the changes in the Nusselt number as well as the pressure drop for variable parameters such as nanoparticle concentrations, magnetic field strength, and channel shape (relative to the circular mode) was investigated. In order to the Grid Independent Study, the Nusselt number for different sizes of grid has been evaluated. As a result, comparing the Nusselt number changes, the average is seen by changing the size of the networking. A grading with the number of 350,000 elements is suitable for simulating the corresponding problem. In order to confirm the validity of the results, simulation of Nusselt number changes during the channel was evaluated and compared with the results presented by Saeed et al. [23]. The error rate between the data presented in reference [23] and the simulation claims is not tangible, and therefore the model used for simulation has been approved. In this study, a triangular channel with a flow inside it is a nanofluid, is analyzed in the presence of a magnetic field in a smooth, completely two phases. For this purpose, the external surface of the channel with a certain heat transfer coefficient and the effect of changes in the thermal and fluid parameters with the change in the parameters involved in the problem have been observed. The results show that with increasing magnetic field, friction coefficient, in-channel velocity, heat transfer rate, average Nusselt number increase. In this study, for simulation we used computational fluid dynamics and limited volume method, and specifically using the Ansys-Fluent version 17 software. The problem is investigated in the form of a three dimensional, stable, single-phase and two-phase flow.
PubDate: Sep 2018
- Influence of the Mills Maintenance on Their Capacity
Abstract: Publication date: Nov 2018
Source:Universal Journal of Mechanical Engineering Volume 6 Number 5 Lidija Joleska Bureska The good working condition of the mills is very important for boilers, which use coal dust. The mills are very important for Power Plants because their work have a direct influence on the combustion process in the boiler furnace. On time controlling the mills condition and their correct repairing during a revision in accordance, technical standards enable unhindered work of the mills with a maximal load. Depending on the coal quality, a maximal load of the mills directly enables increasing of the heat in the boiler. In continue of the paper are shown the characteristic, parameters and capacity of the fans mills during tests: before overhaul (with current maintenance, with partial reparation with a lot of shortcomings) and after overhaul (with complete reparation). According to the received results, a comparative analyze was made for the effect of the mills' condition on the capacity of the boiler and of course of the Power Plant. In order to reach better characteristics of the mills, at the end of paper are mentioned measures for increasing mills‘ capacity for 20t/h with execution technically properly overhaul, with elimination on all gaps in the mills, with improving sealing on the whole coal line etc.
PubDate: Nov 2018
- Comparison of Constraint Elastic Modulus (Ec) Behaviors of Sand Samples
and Derivatives Relative to Stress (σ)
Abstract: Publication date: Nov 2018
Source:Universal Journal of Mechanical Engineering Volume 6 Number 5 Seda Cellek Four different sand samples, designated Type 1, Type 5, Type 9, and Type 13, were selected for this study. The sands were subjected to milling operations of 30 (Types 6, 10, 14), 45 (Types 7, 11, 15), and 60 (Types 8, 12, 16) minutes to produce new samples. For Type 1 sand, new samples were obtained by grinding for 75 (Type 2), 90 (Type 3), and 120 (Type 4) minutes as determined by their mineralogical content. Resulting samples prepared from the Type 1 sand were named Types 2, 3, and 4; from Type 2 were named Types 6, 7, and 8; from Type 9 were named Types 10,11, and12; and finally samples prepared from Type 13 were named Types 14, 15, and 16. Physical properties were determined for Type 1sand at 55, 58, 61, and 73% relative compaction; for Type 5 at 48, 58, 83, and 85%; for Type 9 at 40, 58, 60, 65, and 68%; and for Type 13 at 45, 61, 65, and 68%.The samples prepared from the milled derivatives of the sands were subjected to 40% compaction. Grain distributions were determined to aid in understanding the effects of grain size on Ec. Washed clean sand was used in the study and grain distribution shows poor distribution for all samples. According to this result, while the original sand samples consist of fine and medium grains, the grain sizes of the milled samples vary from fine sand to clay. Mineralogical properties of the sands used in the study were determined. The minerals contained in the sand were determined by Sem (electron microscopy sciences), optical microscope, electron microscope and X-ray diffraction. Results of the examination of the sand samples show that Type 1 sand is made up of augite, hedenbergite, and Anorthite; Type 5 consist of Quartz, Anorthite, Muscovite; Type 9 consist of Quartz, Anorthite; and Type 13 is composed of quartz, anorthite, muscovite, and Anortheclast. In this study, constraint elastic modulus (Ec) values were calculated for sand samples, and various graphics were constructed. The results obtained were analyzed, and an attempt was made to establish the effect of grain size and mineralogy on Ec values by comparison.
PubDate: Nov 2018
- A Tissue Engineering Discussion for Mechanical / Chemical Engineers -
Introducing the Operation of the Stem-Cells Activation Triggers
Abstract: Publication date: Nov 2018
Source:Universal Journal of Mechanical Engineering Volume 6 Number 5 Edilson Gomes de Lima This paper traced an introductory script about the natural communication by an interface between the tissues and the environment theoretically, as a possible form of biological adaptation in environment, as a first step for popularization in tissue engineering for mechanical and chemical engineers. Knowing the keys communication system, it’s theoretically possible to understand that even after generating a specialized tissue, it is still possible to induce new stem cells to generate tissues. According to external and internal tissues readings, as by integrin mechanism, or actomyosin induced by various means, presented throughout this study. Also, make visible and clear new stem cells induction techniques through stimuli, activated by means for the formation of specialized and interconnected specialized cells for tissue engineering. In this objective investigation is showed some mechanical analytical apparatus in new designs to automate biological processes. The domain of all flow and mechanism in stem cell activation triggers is as important as the knowledge of DNA sequencing. With the focus on proving the ability of the tissues to read passively, interpret the external environment and make changes by biochemicals for appropriate adaptation, the genes interpret the environmental stimuli, human senses interfaces and activate adult stem cell niches. External factors along the stem cell are the focus of this investigation, e.g. it has already been proven that a specific nanotopography is a platform to induce differentiation control in stem cells. By nanotopography a stem cell can being induced to become a specific tissue. Through the control and listing these activation keys through mechanical engineering and logic, we can create true artificial tissue factories in high precision innovative scaffolds geometries, with final objective new addictive manufacture and innovative architecture for biological circuits.
PubDate: Nov 2018
- A Numerical Algorithm for the Analysis of the Thermal Stress-Stain State
of a Rod
Abstract: Publication date: Nov 2018
Source:Universal Journal of Mechanical Engineering Volume 6 Number 5 Kanat Amirtayev A universal algorithm for solving applied tasks of thermo elastic state of a partially heat insulated rod of limited length, in the presence of axial force, temperature, heat flow and heat exchange, was developed. The corresponding numerical calculation of efforts of the rod partially thermally insulated and clamped by two ends, in the presence of heat flow was elaborated. The numerical algorithm allowed calculate the lengthening value of the partially thermally insulated rod or the compressive stress and strain in the rods of limited length with the heat flow, the heat exchange, heat insulation and the axial tensile force.
PubDate: Nov 2018
- Optimal Synthesis and Implementation of Resonant Vibratory Systems
Abstract: Publication date: Mar 2018
Source:Universal Journal of Mechanical Engineering Volume 6 Number 2 Volodymyr Gursky Igor Kuzio and Vitaliy Korendiy The problems of synthesis and substantiation of elasticity parameters of the resonant vibratory device with electromagnetic drive and one flat spring are considered. At first, the harmonic systems with oscillation frequencies of 50 Hz and 100 Hz were investigated. Then, various asymmetric piecewise linear characteristics of elasticity were carried into effect on one flat spring using auxiliary intermediary fixed cylindrical supports. Due to this, the corresponding vibro-impact operation modes were obtained. The resonant systems characterized by improved functioning efficiency were carried into effect using the new technique of optimization synthesis of elasticity parameters. The resonant systems being investigated were implemented in practice. The basic experimental investigations of their kinematic, dynamic and energetic parameters were carried out. The fundamental result of the investigation consists in confirmation of the improved dynamic efficiency of vibro-impact systems with pulsed electromagnetic excitation designed according to the new technique. The proposed systems may be used in technological processes of materials compaction and screening, of surface treatment of machine parts and in processes associated with nanotechnology.
PubDate: Mar 2018
- First Principles Study of the New Half-metallic Ferromagnetic Full-Heusler
Alloys Co2CrSi1-XGeX: An Ab-initio Study
Abstract: Publication date: Mar 2018
Source:Universal Journal of Mechanical Engineering Volume 6 Number 2 I. Asfour and D. Rached We present an ab-initio study of the structural, electronic, elastic, magnetic, thermal and thermodynamic property of the quaternary Heusler alloys
(x = 0, 0.25, 0.5, 0.75, 1) with the linearized augmented plane wave method based on density functional theory (DFT) and implemented in WIEN2k code. For exchange correlation potential we have used the generalized gradient approximation (GGA) of Perdew et al. Our results provide a theoretical study for the mixed Heusler 
in which no experimental or theoretical data are currently available. In their equilibrium L21 structure, all concentrations are equilibrium L21 structure; all concentrations are magnetic and metallic. However, there is linear variation of the lattice parameter. The bulk modulus, the elastic constants and the Debye temperature was studied with variation of composition x of Ge. A regular solution model is used to investigate the thermodynamic stability of the alloy which is essentially shows a miscibility gap phase by calculating the critical temperatures of the alloys. In addition, the quasi-harmonic Debye model is applied to determine the thermal properties of the alloy.
PubDate: Mar 2018
- Human Machine Interface Design for a 3 DoF Robot Manipulator
Abstract: Publication date: Jul 2018
Source:Universal Journal of Mechanical Engineering Volume 6 Number 3 Fatih Cemal Can Önder Lapçin Burak Ayan and Mehmet Çevik This paper represents a Human Machine Interface (HMI) design to control a 3 DoF robot manipulator. This manipulator has two parallelograms to make the moving platform always parallel to the ground. We used inverse kinematic analysis of the robot manipulator to control the end point location. Inverse kinematic results are verified using design parameters and end effector location. According to our algorithm, user defines the end point location from HMI, and then program solves inverse kinematics of the robot manipulator. The angles are sent to Arduino microcontroller to set the position of the servo motors. Using this HMI, the user picks and places the object in real time. The user can also give command to draw linear, circular and rectangular paths on the HMI.
PubDate: Jul 2018
- Simulation of Tsunami Effect by Seismic Wave Propagation in Hypoplastic
Medium at Vicinity of Free Boundary
Abstract: Publication date: Jan 2018
Source:Universal Journal of Mechanical Engineering Volume 6 Number 1 Anatoli Chigarev Victor Polenov and Pavel Shirvel A theoretical study of seismic waves propagation in a soil layer with a free surface has a great importance for a prediction in engineering decisions. Wave packets are radiated from an earthquake source and transfer energy. A transformation and a selection of wave packets occur in a process of wave propagating that why waves which arrive in a layer have a length considerably greater than a variation scale of heterogeneity in a medium in a layer near free surface. In the case, when the properties of different layers affect a relatively small degree on a behavior of the waves, an approximation of effective medium gives a fairly good solution. A model of a hypoplastic medium is used for a describing of some effects, which are observed in the time of seismic wave propagation. The model of hypoplastic medium allows describing many effects which are observed in granular soils. We consider a successive application of effective medium and ray methods in order to receive of approximate analytical solutions wishing to describe shear wave propagation in stratified layer, which lies on a half-space.
PubDate: Jan 2018
- Experimental Investigation of Flow Structures around a Torpedo-like
Geometry Placed in a Boundary Layer Flow
Abstract: Publication date: Jan 2018
Source:Universal Journal of Mechanical Engineering Volume 6 Number 1 M. A. H. Hayder I. Goktepeli S. Yagmur M. Ozgoren F. Kose and L. A. Kavurmacioglu Defense applications for both under oceans and seas, particularly underwater vehicles have been considered in this research. With this aim, flow characteristics around a torpedo-like geometry under the effect of the boundary layer flow over a smooth flat plate have been experimentally examined by using PIV technique. All of the experiments have been done for Re=20000 and Re=40000 based on the length (L) of the geometry as a characteristic length. As a result, time-averaged streamwise velocity components
, velocity vectors 
, streamline topologies and Reynolds stress correlations 
in the wake region of the torpedo-like geometry have been acquired in the range of 0 ≤ G/D ≤ 1.5. Here, G is the space between the bottom point of the geometry and flat plate surface; D stands for the diameter of the geometry. It is found that at the smallest value of G/D=0.25, jet-like flow occurs between the plate and the model which causes a powerful scouring. As the gap ratio is increased to G/D=0.5 and G/D=1.0, the jet-like flow diminishes slightly and then the flow structure in the wake region becomes similar to the uniform incoming flow condition for G/D=1.50. Due to the effect of the jet-like flow and boundary layer flow, time-averaged flow patterns present asymmetrical distributions which are clearly shown a bigger size focus close to the plate in streamline topology. Reynolds stress patterns form more powerful viscous forces in the boundary layer flow due to the occurrence of eddy vortices and viscosity effect. It is observed from the aforementioned flow patterns that interaction between the flow structure, the model and boundary layer flow yields very complex structure. In order to decrease the energetic flow in this condition, passive or active flow control method can be integrated on the torpedo-like geometry.
PubDate: Jan 2018
