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Preliminary Designing Method of External Pressure Vessels for Sea Subsurface Applications

Preliminary Designing Method of External Pressure Vessels for Sea Subsurface Applications

This paper describes a unique engineering method intended for the preliminary designing of marine echo-location systems. The solved designing problem consists in determining geometrical parameters and selecting structural materials for a vessel of a buoyancy necessary to contain measuring instruments of a given mass, as well as its maximum gabarites and operational submersion depth. The assumed variability range of the system's parameters determines a space of permissible applicability parameters of the method. Stress level related to permissible and critical stresses was assumed to be safety criterion for the vessel. The method may be applied also to solving converse problems consisting in determining maximum permissible submersion depth for a vessel made of assumed structural materials and having given geometrical parameters. The presented description of the method is illustrated by an example of its application.

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Effect of Compression Garments on Physiological Responses After Uphill Running

each participant was determined by the measurements of leg circumference at the widest part of the calf. Each pair of CS was designed in the same appearance and white color to prevent any placebo effects. The pressure values were measured in vitro and explicitly reported by the manufacturer to ensure their validity. The measuring device used was MST MK IV SALZMANN AG from ST. GALLEN, Switzerland. The required external pressure of tested CS was achieved by calf circumference measurements. Table 1 Pressure applied by compression sleeves at the ankle and below

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Influence of transit water flow rate on its dispensation and on inflow through nozzles in pressure pipeline under action of external pressure

Abstract

The influence of transit flow rate of water upon operative of the equipped with nozzles pressure pipeline is experimentally investigated. External pressure, which varies in the range of 1465-2295 mm, acted upon the pipeline. The angle β between vectors of velocities of the stream in the pipeline and jets which branch off through nozzles were given the value: ; 45° ; 90° ; 135° ; 180°. The diameter of the pipeline was of D=20.18 mm, the diameter of nozzles d=6.01 mm. The distances between the nozzles were 180 mm, and the number of them 11. The value of the transit flow rate at input into the pipeline varied from 4.05 to 130.20 cm3 / s. The increase in flow rate of the transit flux Qtr caused increase in non-uniformity of distribution of operating heads and increase in flow rate of water along the pipeline over the segment of its dispensation. On the segment of collecting of water, inverse tendency was observed. The number of nozzles through which water became to be dispensed increased with the increase in Qtr.

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Buckling Capacity Curves for Steel Spherical Shells Loaded by the External Pressure

Abstract

Assessment of buckling resistance of pressurised spherical cap is not an easy task. There exist two different approaches which allow to achieve this goal. The first approach involves performing advanced numerical analyses in which material and geometrical nonlinearities would be taken into account as well as considering the worst imperfections of the defined amplitude. This kind of analysis is customarily called GMNIA and is carried out by means of the computer software based on FEM. The other, comparatively easier approach, relies on the utilisation of earlier prepared procedures which enable determination of the critical resistance pRcr, the plastic resistance pRpl and buckling parameters a, b, h, l 0 needed to the definition of the standard buckling resistance curve. The determination of the buckling capacity curve for the particular class of spherical caps is the principal goal of this work. The method of determination of the critical pressure and the plastic resistance were described by the authors in [1] whereas the worst imperfection mode for the considered class of spherical shells was found in [2]. The determination of buckling parameters defining the buckling capacity curve for the whole class of shells is more complicated task. For this reason the authors focused their attention on spherical steel caps with the radius to thickness ratio of R/t = 500, the semi angle j = 30o and the boundary condition BC2 (the clamped supporting edge). Taking into account all imperfection forms considered in [2] and different amplitudes expressed by the multiple of the shell thickness, sets of buckling parameters defining the capacity curve were determined. These parameters were determined by the methods proposed by Rotter in [3] and [4] where the method of determination of the exponent h by means of additional parameter k was presented. As a result of the performed analyses the standard capacity curves for all considered imperfection modes and amplitudes 0.5t, 1.0t, 1.5t were obtained. Obtained capacity curves were compared with the recommendations for different fabrication quality classes formulated in [5].

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Buckling Analysis of Orthotropic Thick Cylindrical Shells Considering Geometrical Imperfection Using Differential Quadrature Method (DQM)

Conditions Under External Pressure. Journal of Theoretical and Applied Mechanics , 52 (2014) no. 1, 25-36. [15] S emenyuk , N. P., N. B. Z hukova . Stability and Post-buckling Behavior of Orthotropic Cylindrical Shells with Local Deflections, International Applied Mechanics , 52 (2016) No. 3, 290-300. [16] W interstetter , T. A., H. S chmidt . Stability of Circular Cylindrical Steel Shells Under Combined Loading. Thin-Walled Structures , 40 (2002), 893-909. [17] L ai , W. M., D. R ubin , E. K rempl . Introduction to Continuum Mechanics. 3rd ed

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Snap-Through of the Very Shallow Shell with Initial Imperfection

Abstract

Elastic shallow shell of translation subjected to the external pressure is analysed in the paper numerically by FEM. Nonlinear equilibrium paths are calculated for the different boundary conditions. Special attention is paid to the influence of initial imperfection on the limit load level of fundamental load-displacement path of nonlinear analysis. ANSYS system was used for analysis, arclength method was chosen for obtain fundamental load-displacement path of solution.

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The Determination of Pressure Drop of Filter Rods and Nozzles under Different Atmospheric Pressure Conditions/Messung des Zugwiderstandes von Filterstäben und Düsen unter verschiedenen Luftdruckbedingungen

Abstract

The relations between the pressure drop values of filter rods and nozzles obtained by customary gauges and the atmospheric pressure are investigated. Measurements are carried out between 500 and 1.000 mm Hg external pressure. This range was produced artificially. In case of filter rods it is shown, that a variation of 4 % only is received on the full measuring range by operating at constant air circulation (cm3/s) independent of atmospheric pressure. This shift is negligible in view of normally occurring local variations of atmospheric pressure. By operating at constant air circulation (cm3/s) the value of the nozzles' pressure drop varies in considerable degree over the full measuring range. Using reference nozzles for devices of pressure drop determination at different altitudes therefore, either a correction of the reference mark fixed at a standard pressure is necessary, or the values for filter pressure drop are to be corrected. The corrections are indicated.

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CFD Simulation of Air Flow Over an Object with Gable Roof, Revised with Y+ Approach

Abstract

Aim of this contribution is to provide insight view into analysis focused on obtaining external pressure coefficients on isolated two storey low-rise building with 15° elevation gable roof using Computer Fluid Dynamics simulation and these are compared to values that offering Eurocodes. Final Volume Model consisting of polyhedral mesh will be used for analysis with two different turbulence models. Mesh was created with respect to y+ parameter, where desired value was below one which leads us to fine mesh type. Secondary aim of this contribution is to compare performance of selected turbulence models. For this purpose were chosen Detached Eddy Simulation and Large Eddy Simulation which are part of the Scale Resolving Simulation turbulence models.

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Study Regarding the Defense Expenditure Analysis in Nato

Abstract

Armed conflicts are a reality of the present world. Military power is an active actor in domestic and international relations. Defense must have the financial allocations necessary to sustain a flexible and modern army. The macroeconomic and geostrategic factors, including the change of power poles from the West to the East, the demographic changes and the limited resources are elements that will deeply reconfigure the trends in military expenditure. This is the case in less developed areas of the world where trends will bring instability and will put additional, internal and external pressure on the challenges of defense and security. NATO countries have assumed the 2% of GDP target for defense expenditure, but are making great efforts to reach this level. In 2016, only 4 out of 29 NATO members, or 14% reached the target of 2% of GDP for military expenditure and 20 out of 29 NATO countries spent less in absolute terms in 2016 compared to 2014

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Sri Lanka: Physical Reconstruction and Economic Development as Conflict Prevention Factors

ABSTRACT

This article gives an overview of the 26 year long ethnic conflict in Sri Lanka and examines physical reconstruction and economic development as measures of conflict prevention and postconflict reconstruction. During the years of conflict, the Sri Lankan government performed some conflict prevention measures, but most of them caused counter effects, such as the attempt to provide “demilitarization”, which actually increased militarization on both sides, and “political power sharing” that was never honestly executed. Efforts in post-conflict physical reconstruction and economic development, especially after 2009, demonstrate their positive capacity as well as their conflict sensitivity. Although the Sri Lankan government initially had to be forced by international donors to include conflict sensitivity in its projects, more recently this has changed. The government now practices more conflict sensitivity in its planning and execution of physical reconstruction and economic development projects without external pressure.

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