Brain drain: Propulsive factors and consequences

When speaking about the total number of highly educated individuals’ migration, it is easy to spot that it is rapidly increasing. The brain drain issues should be taken very seriously especially in under developed and in the developing countries, knowing that the human capital is globally mobile and that highly educated individuals can without any issues market their knowledge around the globe. Dealing with it requires a carefully tailored strategy for these countries, which are suffering from severe human capital losses on annual basis. Since the labor markets of today are highly competitive, it is necessary for these countries to secure good advancement and doing business opportunities. The purpose of this research is to provide an insight into the key propulsive factors and potential consequences caused by the brain drain. The method used in order to conduct the research was a carefully designed questionnaire taken by the date subject enrolled at the third and fourth years of state governed and privately owned universities. This research shows that one of the key reasons for brain drain in underdeveloped and in the developing countries is shortage of further educational advancement opportunities

Measurements and modeling pollution from traffic in a street canyon: Assessing and ranking the influences

More than half a century, the scientific community is trying to understand the mechanisms and conditions of pollution dispersion within urban areas. Thereat, special attention has been focused on specific areas, such as a street canyon, in which harmful concentrations higher than allowed are more likely registered. However, there is still a controversy about the conditions of occurrence and impact of the individual air pollution components due to fluctuations of key contributions. Given that OSPM is a well-known semi-empirical model specializing in the assessment of air quality within a street canyon. After its testing and validation, the results of subsequent simulations were used as a basis for planning a special experiment in order to implement 48 full factorial designs. Using the response surface methodology, as the final objective, an answer was precisely given on the impact and contribution of urban air pollution components. In addition to the main objective of this study, as a secondary, but not less important result defining emission factors for CO and NOx can be emphasized, which to date have not been determined for the fleet of Serbia

Finite element simulation of tensile test of composite materials manufactured by 3D printing

© 2020 Institute of Physics Publishing. All rights reserved. A principle of 3D printing is based on formation of continuous layers of materials up to a formation of the final shape. Materials for production of given components are composite materials, especially on the basis of so-termed CFRP, CRP, (carbon fibre - so-termed polymers reinforced by carbon fibres). The objective of this paper is to predict the deformation length of carbon/onyx composite laminates using Finite Element Analysis (FEA) and compare with universal testing machine INOVA FU 160 deformation results through the tensile load. Specimen were printed at raster orientation angles of 0°, 45° and 90° to test orientation effects on part strength. 16 ply CFRP specimens with various stacking sequences were analysed for their strength and displacements. A shell model has been established for simulation of the tensile test composite specimen which enables to understand the mechanical strength and strain at failure of the composite materials. The simulations of experiment are provided in FEM program ANSYS and ANSYS/Workbench

Influence of imperfections on dynamic properties of oscillating rod

© 2020 Institute of Physics Publishing. All rights reserved. The paper deals with the analysis of the influence of boundary conditions on the dynamic properties of a mechanical system. The steel bar is fixed in one place so that it is inserted under the hydraulic press. The pressure force in the press changes and models the imperfect fixation of the bar. The effect of bond imperfection is evaluated based on rod vibration analysis. This problem is solved computationally, by FEM and the results are compared with experimental measurement

Failure criteria of fibre reinforced composites in homogeneous temperature field

The present paper examines the failure criteria of layered composites with orthotropic properties in the homogeneous temperature field. The composite has modeled by two mechanically equivalent families of fibres. The paper formulates constitutive equations in terms of intrinsic preferred directions, which are defined by the orientation of fibers at any point of the composite. A uniformly heated, thermoelastic solid undergoes distortion as well as volume change because it experiences differential expansions in different directions. This effect is more complicated if, in addition of being anisotropic, the material is inhomogeneous, as in the case with laminated materials. In order to illustrate the influence of temperature on the failure of this group of materials constitutive equations are derived and adoptedforuse in failure criteria, without the influence of temperatures, and with the influence of increased temperature

Foreign body extraction through the rigid bronchoscopy

Introduction. Foreign body aspiration into tracheobronchial tree represents an urgent condition at high level of risk. Etiology is different, and this condition is typical for all ages with highest incidence in pediatric population. Case report. A successful foreign body removal (partial denture) in a 34-year old man was presented. Radiography and computerized tomography of the chest showed a foreign body localized at the level of the right bronchus including the right middle lobe bronchus. By the use of rigid bronchoscopy, a foreign body was visualized and mobilized from the segmental bronchus in the first act, and then completely extracted. Conclusion. Efficient diagnostics and extraction are imperative for the aspirated foreign body preventing life-threatening complications

Morphometric analysis of collagen and inflammatory cells in periodontal disease

© 2015, Institut za Vojnomedicinske Naucne Informacije/Documentaciju. All rights reserved. Background/Aim. Periodontal disease affects gingival tissue and supporting apparatus of the teeth leading to its decay. The aim of this study was to highlight and precisely determine his-tological changes in the gum tissue. Methods. Gingival biopsy samples from 53 healthy and parodontopathy-affected patients were used. Clinical staging of the disease was performed. Tissue specimens were fixed and routinely processed. Sections, 5 μm thin, were stained with hematoxylin and eosin, histochemical Van-Gieson for the collagen content, Spicer method for mast-cells and immunochemical method with anti-CD68 and anti-CD38 for the labelling of the macrophages and plasma-cells. Morphometric analysis was performed by a M42 test system. Results. While the disease advanced, collagen and fibroblast volume density decreased almost twice in the severe cases compared to the control ones, but a significant variation was observed within the investigated groups. The mast-cell number increased nearly two times, while the macrophage content was up to three times higher in severe parodontopathy than in healthy gingival tissue. However, the relative proportion of the-se cells stayed around 6% in all cases. Plasma-cells had the most prominent increase in the number (over 8 times) com-pared to the control, but again, a variation within investigated groups was very high. Conclusion. Gingival tissue destruction caused by inflammatory process leads to significant changes in collagen density and population of resident connective tissue cells. Although inflammatory cells dominated with the disease advancing, a high variation within the same investigated groups suggests fluctuation of the pathological process

Determination analysis of temperature regimes, functional characteristics and sliding curves of a hydrodynamic clutch

Analysis of output quality of power transmitters is possible in position when characteristics are determined earlier. This is the reason why we focused on determination of these characteristics for a concrete power hydro-transmitter. This means that the investigation task primarily consisted of determination of functional characteristics, defining of the sliding curves and temperature regimes of a concrete hydrodynamic clutch. Results of velocity and pressure field investigations in the working space of this clutch, obtained by use of the same test setup, are the basis for determination and analysis of the functional characteristics, sliding curves and temperature regimes. In this work we also analyzed function of the hydrodynamic transmitter in assembly with an internal combustion engine, as well as a process of acceleration and deceleration of a vehicle with this assembly in it

VARIABLE DRAWBEAD HEIGHT AND VARIABLE CONTACT PRESSURE AS TRIBOLOGICAL INFLUENCES IN SHEET METAL STRIPE SLIDING TEST

For this experimental research, electro-hydraulic computerised device for sheet metal stripes sliding was made. Its main property is realisation of contact pressure and drawbead height as functions dependent on time, i.e. stripe travel. In addition, it is also possible to measure drawing force, pressure, drawbead displacement, etc. The paper presents the preliminary results of the investigation of decreasing drawbead height influence in combination with increasing-decreasing contact pressure function. The stripes are made of low-carbon steel sheet metal of 0.8 mm thickness. Contact conditions are influenced additionally in 2 ways – by mineral oil lubrication, and dry surfaces application. Drawbead geometry, with rounding radii of 2 and 5 mm, is also varied. The results indicate that simultaneous influence of variable drawbead height, variable contact pressure, drawbead geometry and proper friction conditions can influence substantially the plastic flow process.Publishe

TRIBOLOGICAL PROPERTIES OF STEEL AND AL-ALLOYS SHEET METALS INTENDED FOR DEEP DRAWING

During the last few years, aluminium alloys are increasingly more used in production of light constructions, especially for manufacture of light car bodies of passenger cars. From the aspect of tribological factors influence, experience in application of low-carbon steel sheet metals in manufacture of car body parts by deep drawing procedures up to now differs significantly regarding the application of Al-alloys. The paper presents the experimental results of tribological investigations of specified materials properties at sliding tests, as well as results at deep drawing with variable blank holding force. The combination of unfavourable formability parameters and sensitivity to tribological conditions at application of Al-alloys requires a particular approach to tools and technology designing in comparison with classic forming procedure.Publishe