Papers by Keyword: Injection

Abstract: In this study, we conduct a techno-economic comparative analysis between traditional manufacturing and 3D printing technology (i.e., additive manufacturing (AM)) for fused deposition modeling (FDM) --based finger casts. Manufacturing costs are initially collected for machine cost, material cost, and labor cost, in which the Monte Carlo method is also implemented to simulate the number of pieces manufactured in each manufacturing cycle. Traditional manufacturing based on injection technology is found to have high manufacturing costs due to the mold requirement, in which the economies of scale are applied with the increase in manufacturing quantity. In addition, manufacturing costs with AM technology are analyzed using the Cura platform to assess the designed experiment from the FDM-based AM printer to fabricate single and multiple healthcare workpieces per time, respectively. In particular, the breakeven point analysis is investigated, where manufacturing one and five workpieces with AM technology is comparable to producing 1,854 and 6,048 pieces using traditional, injection manufacturing technology in our exemplified case study. The results from the techno-economic evaluation in this study are expected to be further used as a guideline for studies relevant to operational and tactical planning for AM-related applications.

Abstract: The purpose of this paper is to investigate the Soret and Dufour effects on unsteady mixed convective boundary layer flow of a viscous fluid over a stretching surface in a porous medium in the presence of magnetic field with heat generation/absorption, chemical reaction, suction/injection and convective boundary condition. The governing time-dependent partial differential equations are transformed into non-linear ordinarydifferential equations using similarity transformations. These equations subject to the appropriate boundary conditions are solved analytically by homotopy analysis method (HAM) and numerically by Runge-Kutta fourth order method and shooting technique.The numerical solution is compared with analytical solution. The influence of the different parameters on velocity, temperature and concentration profiles are discussed in graphical as well as in tabular form. It is observed that the fluid velocity and temperature increase on increasing the buoyancy ratio parameter and heat generation/absorption parameter. Also found that the surface heat and mass transfer rates increase on increasingthe suction/injection and heat generation/absorption parameters.

Abstract: This paper is devoted to find analytic approximate solution by optimal homotopy asymptotic method (OHAM) for the problem of nonlinear boundary layer flow. Two-dimensional magneto-hydrodynamic (MHD) flow of a viscous fluid over a moving wedge in porous medium with suction/injection is investigated. Governing equations are transformed by similarity method into a third order Falkner-Skan equation and solved analytically using OHAM. This approach is highly efficient, ensuring a very rapid convergence of the solution only after one iteration. Graphical results are presented to discuss the effects of various parameters on velocity profiles. Further, the skin friction coefficient is also tabulated and compared with the corresponding results available in literature. Our results were found in an excellent agreement.

Abstract: Effect of suction/injection on the rate of entropy generation of third grade fluid with convective cooling is analysed in this work. The highly non-linear boundary value problems obtained from the governing equations are solved by Adomian decomposition method (ADM). Some plots are presented to explain the influence of pertinent parameters on fluid motion, temperature, entropy generation and irreversibility ratio. From the results it is shown that suction/injection and third grade fluid parameters reduce fluid velocity across the channel, and increase in suction/injection parameter enhances fluid temperature while convective cooling parameter reduces it. Entropy generation is enhanced by suction/injection parameter at the lower wall but reduces it at the upper wall

Abstract: The injection behavior of β-tricalcium phosphate (Ca₃(PO₄)₂: β-TCP) based cement was improved through the granulation of β-TCP. Dense β-TCP granules were obtained by heat treatment after spray drying. The fraction of injected paste under loaded mass in the syringe was measured while varying the granular fraction of β-TCP and the heat treatment temperature. The increase in granular fraction and heating treatment temperature reduced the amount of setting agent required to wet the granules. As the surplus setting agent could be used in the powdery β-TCP to reduce the viscosity, improved injectability was achieved. Inappropriate setting by the excessive setting agent was not observed and the cements tested exhibited normal setting behavior by forming a brushite phase.

Abstract: Often, when it is necessary to fill formwork space in confined working conditions with limited operational control in some engineering solutions the special materials for injection are used. In this case, it is advisable to use high-fluidity concrete mixes made with К-cement, regulator of the kinetics of structure formation, superplasticizer and gas-forming admixture. The gas-forming admixture obtains of expansion of fresh-concrete during first stage. The special sulfo-alumina additive in K-cement obtains of expansion of hardening concrete during second stage. The main regularities in the formation of the structure and properties of cement stone are considered. The dependences "composition-technology-structure-properties" for concretes with two-stage expansion are clarified. The main provisions for determination of mix proportion for concrete are proposed. The quantitative relationships between the construction properties of concretes and prescription and technological factors are obtained.

Abstract: In this paper, both first and second laws of thermodynamics are employed to investigate the combined effects of magnetic field, buoyancy force, velocity slip, suction/injection, porous medium permeability, thermal radiation absorption, viscous and Joule heating on mixed convective flow of an electrical conducting Casson fluid in a vertical channel. The dimensionless governing equations are obtained and solved numerically using a shooting technique coupled with a fourth order Runge-Kutta-Fehlberg integration scheme. The influence of various thermophysical parameters on velocity and temperature profiles, skin friction, Nusselt number, entropy generation rate and Bejan number are presented graphically and discussed quantitatively. It is found that with appropriate combination of thermophysical parameter values the entropy generation rate in the presence of an applied magnetic field can successfully.

Abstract: This paper discusses the thermodynamics irreversibility in an unsteady hydromagnetic mixed convective flow of an electrically conducting optically dense fluid over a permeable vertical surface under the combined influence of thermal radiation, velocity slip, temperature jump, buoyancy force, viscous dissipation, Joule heating and magnetic field. The governing partial differential equations are reduced to ordinary differential equations by using similarity variable. A local similarity solution is obtained numerically using shooting technique coupled with Runge-Kutta Fehlberg integration method. The influence of various thermophysical parameters on velocity and temperature profiles, skin friction, Nusselt number, entropy generation rate and Bejan number are presented graphically and discussed quantitatively. It is found that velocity slip, surface injection and temperature jump can successfully reduce entropy generation rate in the presence of an applied magnetic field. A comparison of numerical solution is made with the exact solution under a special case scenario and excellent agreement is found.

Abstract: The objective of the present study is to investigate the heat and mass transfer characteristics of the MHD stagnation-point flow of gyrotactic microorganisms contained nanofluid past a nonlinear stretching/shrinking sheet in presence of space and temperature dependent internal heat generation/absorption with suction/injection. The governing partial differential equations are transformed to system of ordinary differential equations by using similarity transformation and then solved numerically using Runge-Kutta based shooting technique. The influence of non-dimensional governing parameters on velocity, temperature, nanoparticle volume fraction and density of the motile microorganisms along with friction factor, local Nusselt number, local Sherwood number and the local density of the motile microorganisms was discussed and presented through graphs and tables. Dual solutions are presented for certain range of suction and injection parameters. The validity of the present results compared with the existed results.

Abstract: Uncontrolled growing of construction industry in Turkey has caused a large number of buildings were constructed without the benefit of sufficient engineering supervision. These phenomena have contributed to the increase in the number of seismically weak buildings. After the Great Marmara Earthquake seismic performances of the existing structures have been inspected and some of them fortified. In this context, an existing building foundation, built on a problematic soil and located in Denizli where is in high seismic risk area, has been strengthened by cement injection. Grouting holes up to 7 m in depth from the basement level were used in 45 points. The injection has created a less permeable barrier, acts like an underground dam. This barrier has caused rising of the underground water table around the recharge area of the foundation. The raised underground water has increased hydraulic gradient and hydraulic pressure. Then, the basement floor has arched up to 12 cm and underground water has risen up to 30 cm high after one year of the injection practice. In this study, hydrogeological characteristics of the soil structural analysis have been evaluated and some solutions suggested remedying the problem. It should be kept in mind as injection practice is employed in aquifers.