Interfacial phenomena during drop coalescence in polymeric systems

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Influencing factors on effective width of compressed zone in joint column - cylindrical shell of steel silo

In order to ensure unloading of whole amount of stored product by gravity, steel silos are often placed on supporting structure. The simplest way to design these complicated facilities is to divide cylindrical shell on two parts in our minds - discretely supported ring beam and continuously supported shell above it. Obviously, to ensure continuously support of shell, bending stiffness of ring beam should be high. In European standard EN 1993-4-1, that concept is recognized but it keeps silence about recommended stiffness of ring beam. Another way to design is to know law of distribution of compressive axial stresses due to discrete column reactions R, by height of shell. Knowing it, we could calculate the effective width leff of distribution of compressive stresses on every level. Where effective width is equal to distance between discrete supports, there critical height of shell ends and above it cylindrical body is continuously supported. Unfortunately the above quoted standard EN 1993-4-1 does not give an information how to calculate leff. The questions here are; should we accept linear distribution of compressive forces by height? In addition, could we use directly the results of Whitmore (1952), where angle of distribution α = 30°? Or, even to accept a far more brave opinion that α = 45°, used by many of the elder designers? Moreover, is value of angle α constant or does it depend on various influencing factors

Business Cycles in Bulgaria and the Baltic Countries: An RBC Approach

This paper explores the business cycle in Bulgaria and the Baltic countries: Estonia, Latvia and Lithuania during the 1993-2005 period. The paper aims at deepening the understanding of the nature of output fluctuations. The neoclassical approach will be employed, much in the spirit of the Real Business Cycle (RBC) literature, which gives a general equilibrium picture of the transition process. The model used in this paper follows the methodology of King, Plosser and Rebelo (1988). Calibration parameters, taken from data on Bulgarian and Baltic economies, are used in the estimation procedure. Both the model and data series show that the major drop in output was due to productivity. In addition, the timing of the banking reforms coincides with the improvement of economic performance. This is a strong indication that banking regulations in place were crucial for the output performance throughout the period in Bulgaria and the Baltic countries, a finding that has important implications for economic policy

Vertical stiffeners and internal pressure - influencing factors on distribution of meridional stresses in steel silos on discrete supports

Steel silos are interesting, complicated facilities. In order to ensure unloading of whole amount of stored product by gravity, they are often placed on supporting structure. Values of stresses in joints between thin sheets and supporting frame elements are very high, which could cause local loss of stability in thin shells. Many researchers have worked on values and distribution of the meridional stresses in that joints. Their traditional approach is to divide in their minds cylindrical shell on two parts - discretely supported ring beam and continuously supported shell above it. As a result of their efforts critical height of shell Hcr and ideal position of intermediate stiffening ring on shell are determined. The scientific results are based on semi-membrane theory of Vlasov, in which influence of vertical stiffeners and internal pressure is not accounted. On other hand all steel silos are loaded with an internal pressure and majority of them have vertical stiffeners above supports. Is it possible the obtained scientific results to be applied to these silos? In a present article the author will show that stiffeners and pressure should not be ignored in an analysis

Arch effect in silos on discrete supports - Is it a myth or reality?

Steel silos are interesting, complicated facilities. In order to assure its complete emptying by gravity they are often placed on supporting frame structure above the ground. Values of stresses in joints between thin walled shell and supporting frame elements are very high. It can cause the local buckling in the shell. The simplest way to design steel silos is to divide hypothetically the cylindrical shell into two parts - ring beam, supported in some points and shell above, uniformly supported. This conception is accepted by European Standard EN 1993-4-1. The particular moment is that the ring beam and cylindrical body above it are separated. Actually the two elements are jointed and work together in the same time. Considering the last results of Zeybek, Topkaya and Rotter from 2019, and as well as his own research, the author asks the question if it is true that the transferring of discrete base reactions to the cylindrical body is done by bending work of the ring beam, which is the conception in EN 1993-4-1? Or the vertical reaction forces are actually redistributed on the height based on the work of the cylindrical shell under compression as an arch. Using the contemporary capabilities of the programs for spatial analysis of building structures the author will try to find the answer of this question

METHODOLOGY FOR EVALUATION OF STRATEGIC DOCUMENTS

The nature of the strategic documents and the mechanisms for their updating require improvement of the strategic planning apparatus. Despite the existing actions in this direction, there is still no universal state standard and mature regulatory framework to harmonize and regulate the entire process in the Republic of Bulgaria. The report summarizes efforts to create a new toolkit bringing together proven practices in the subject area. A Methodology for the evaluation of strategic documents is presented, which offers a comprehensive and systematized approach to the evaluation of conformity according to the procedure of creation, structure, consistency, content and attainability