Formiranje baznog modela transporta poljoprivrednih proizvoda

In this paper basic principles of transport organization in agriculture are presented as well as details about the transportation cycles. The paper also gives all necessary inputs for the model definition regarding the transportation for the agricultural products. The paper deals with the development of the basic model for calculation of the necessary resources in optimal transportation organization. Development of the plan is very important and the plan itself is only a single document in the given time section. Development of such a plan should make planning and development of the basic plan easier. The most important part of this research was to define and analyze all the necessary inputs for the optimal organization of the agricultural product transportation.U radu su objašnjeni principi organizacije transportnog procesa i transportnog ciklusa i dati su svi potrebni inputi za formiranje baznog modela transporta poljoprivrednih proizvoda. Predmet ovog rada je razvoj baznog modela transporta i proračun potrebnih resursa. Izrada plana je bitna i bitan je plan kao dokument po kome se postupa, ali plan je samo jedan dokument u datom preseku vremena. Upravo razvoj ovakvog modela treba da omogući lakše planiranje i izradu osnovnog plana i sve njegove naknadne korekcije. Praktičan cilj rada su osnovni parametri modela neophodni u procesu planiranja optimizacije transportnih sistema

Interactions of Fast Ions with Graphene

In this work, we study the interactions of fast ions with graphene describing the excitations of the electron gas in graphene by a two-dimensional (2D) hydrodynamic model (one-fluid and two-fluid model). The two-fluid model reproduces qualitatively the split of plasmon dispersions into the low-frequency pi-electron branch and the high-frequency sigma+pi-electron branch. We calculate the stopping force and the image force on an ion moving parallel to a single sheet of graphene. Numerical results show that the presence of the low-energy, quasiacoustic plasmon in the two-fluid model gives rise to resonant features at low velocities around its acoustic speed, which are not seen in the one-fluid model. The two models give virtually indistinguishable results for both forces at high speeds. Marked differences between the two models in the values of image forces at low speeds can be seen. Numerical results show that the magnitudes of both the stopping and image forces exhibit typical resonance-shaped velocity dependencies, with the peak positions moving to higher velocities for higher distances and with the overall magnitudes decreasing sharply with increasing distances. The second order corrections are found to be small, as expected for fast ions outside the electron gas, but their relative magnitudes should be easily discernible in experiments on ion grazing scattering from graphene. One notices effects which are similar to those obtained earlier for proton channeling in carbon nanotubes.7th Seminar of Young Researchers, Dec 22-24, 2008, Belgrade, Serbi

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

The effect of pipe corrosion upon the reliability of a thermal power plant

Prikazani su rezultati ispitivanja korozije cevi i sastava korozionih naslaga na cevima i delovima jednog termoenergetskog postrojenja. Vršena je rendgenostrukturna analiza. Uzorci su zatim posmatrani na svetlosnom mikroskopu, a slikanje uzoraka vršeno je digitalnom kamerom. Na digitalnim mikrofotografijama merena je debljina korozionog sloja. Na osnovu rezultata ispitivanja korozije ukazano je kako korozija utiče na pouzdanost rada postrojenja, kao i to kako ovim rezultatima uticati na upravljanje pouzdanosti postrojenja.The results of an investigation of the corrosion and corrosion products on the pipes of an thermal power plant are presented.X-ray diffraction analysis was done.Samples of the pipes were observed oa a light microscope and photographed with a digital camera.The thickness of the corrosion layer was measured on the digiatal photographs.Based on these results it was shown how corrosion effects the reliability of the power plant and how to use these results to manage the reliability of the power plant

Analysis of grease contamination influence on the internal radial clearance of ball bearings by thermographic inspection

One of the most important factors influencing ball bearings service life is its internal radial clearance. However, this parameter is also very complex because it depends on applied radial load and ball bearings dimensions, surface finish and manufacturing materials. Thermal condition of ball bearings also significantly affects internal radial clearance. Despite many researches performed in order to find out relevant facts about different aspects of ball bearings thermal behaviour, only few of them are dealing with the real working conditions, where high concentration of solid contaminant particles is present. That’s why the main goal of research presented in this paper was to establish statistically significant correlation between ball bearings temperatures, their working time and concentration of contaminant particles in their grease. Because of especially difficult working conditions, the typical conveyor idlers bearings were selected as representative test samples and appropriate solid particles from open pit coal mines were used as artificial contaminants. Applied experimental methodology included thermographic inspection, as well as usage of custom designed test rig for ball bearings service life testing. Finally, by obtained experimental data processing in advanced software, statistically significant mathematical correlation between mentioned bearings characteristics was determined and applied in commonly used internal radial clearance equation. That is the most important contribution of performed research - the new equation and methodology for ball bearings internal clearance determination which could be used for eventual improvement of existing bearings service life equations. [Projekat Ministarstva nauke Republike Srbije, br. TR35029 i br. TR14033

Wake effect in interactions of dipolar molecules with doped graphene

We study the wake effect in the charge carrier density in free graphene induced by an electric dipole moving parallel to it by using the dynamic polarization function of graphene within the random phase approximation for its pi electrons described as Diracs fermions. We show that, while the equilibrium doping density of graphene sets a length scale for the period of the wake via graphenes Fermi wavenumber, qualitative properties of the wake are strongly affected by the speed of the dipole, its distance from graphene, and the dipole moment orientation. (C) 2013 Elsevier B.V. All rights reserved

Wake effect in doped graphene due to moving external charge

We use the dielectric-response formalism to evaluate the induced density of charge carriers in supported graphene due to an external moving charged particle in terms of its velocity and distance from graphene for several equilibrium charge carrier densities due to graphene doping. We show that, when the particle speed exceeds a threshold value, an oscillatory wake effect develops in the induced charge density trailing the particle. Strong effects are observed in the wake pattern due to finite size of the graphene-substrate gap, as well as due to strong coupling effects, and plasmon damping of graphenes pi electrons. (C) 2011 Elsevier B.V. All rights reserved