Concept Of Equivalent Diameter Research Articles

Behavior and design-oriented model for elliptical FRP-confined concrete under axial compression

Elliptical fiber-reinforced polymer (FRP)-confined concrete members have gained increasing attention due to their aesthetical characteristics and structural efficiency. This paper investigated the behavior of 24 elliptical FRP-confined concrete stub columns under axial compression. Effects of the amount of FRP confinement, the cross-sectional aspect ratio, and the use of high-strength concrete were discussed. The test results indicated that the stress and strain capacities of the confined concrete were enhanced with the increasing amount of FRP confinement. By contrast, the increasing sectional aspect ratio and the use of high-strength concrete had an adverse effect on the inner concrete’s axial behavior due to the increasingly non-uniform distribution of FRP confining pressure. In general, the typical stress–strain curves of elliptical FRP-confined concrete were categorized into four types. Furthermore, using the concept of equivalent diameter, the threshold for sufficient confinement of elliptical FRP-confined concrete was determined by the equivalent confinement stiffness ratio to ensure an overall ascending behavior. After addressing some key issues, a design-oriented model for elliptical FRP-confined concrete with a relatively wider range of concrete strength (from 32.6 to 72.4 MPa) was developed herein with more satisfactory accuracy than existing models. This model with a simple form could be naturally reduced to a widely accepted model for FRP-confined concrete with circular sections.

Performance evaluation of analytical expressions for cylindrical and rectangular deep drawing force estimation

The deep drawing force (DDF) is defined as the maximum force required to perform a given deep drawing operation. The DDF is needed to design the drawing tools, to define the press capacity and to estimate the drawing work and process efficiency. Although several expressions to estimate the DDF have been proposed in the literature, particularly for cylindrical parts, very few research works have focused on their evaluation in terms of prediction performance. Moreover, a limited number of expressions to estimate the DDF of rectangular parts have been reported in the literature.In this paper, an investigation to evaluate and compare different analytical expressions to estimate the DDF of cylindrical and rectangular parts is presented. The aim of this investigation is twofold: first, to propose new expressions to estimate the DDF of rectangular parts, and second, to evaluate the prediction performance of the DDF expressions for cylindrical and rectangular parts. Initially, several DDF expressions for cylindrical parts are identified and analysed. These expressions are then transformed into equivalent expressions for rectangular parts by using the equivalent diameter concept. The prediction performance of these DDF expressions for cylindrical and rectangular deep drawing is then quantified and analysed based on experimental data from the literature. Finally, the influence of the deep drawing parameters on the DDF is also presented and analysed.

Development of a method and technology for obtaining vegetable oil from safflower seeds

The article is designed and engineered compact line for processing grain safflower, which used the equipment of the increased efficiency, implementing progressive processes with application of modern physical methods of treatment. This line includes bucket Elevator (Noria), a receiving hopper , the air-sieve separator , intermediate tank, Trier (osgoodby and qualitronic), stone-dividing machine and separator for separation of Caucalis lappula, screw conveyor, intermediate bunker, peeler, oil press machines, the device for the deposition of oil (the sump), pump, frame filter. The process of collapse in the grinding pilot plant, in which the destruction of the epithelial layer of the shell is due to the fact that the compression stress in the impact zone exceeds the limit of elastic deformation of the shell of the grain. Conducted sieve analysis, which was studied granulometric composition fed to the compression of the particles of safflower seed , in this case to characterize the granulometric composition of the raw material, consisting of particles of irregular shape, used the concept of equivalent diameter. As a result of the experiments was the dependence of the equivalent particle diameter from the diameter of the sieve. Since the degree of extraction of safflower seed are hugely influenced by the moisture source of the product, was therefore carried out experimental studies of compaction with different moisture content of the seeds , and with the addition of Luz-Ki. From the analysis of graphic dependences were established a range of optimum moisture safflower seed 8,5--10%, providing the lowest residual oil content and hence the greatest yield of oil. Also managed to significantly increase the efficiency of extraction of oil by adding safflower seed pre-milled husks, which allowed to obtain cake with a residual oil content of 12% when you multiply pre-pressing and to 6% at the final extraction

ANALISIS TEÓRICO-NUMÉRICO-EXPERIMENTAL DE UN PROCESO DE HIDROCONFORMADO USANDO DIÁMETRO EQUIVALENTE

The main goal of this work is to propose the application of the concept of equivalent diameter in the calculation of the hydraulic pressure required to conduct an hydroforming process in non-circulars pieces. Although this approach was carried out initially for the conventional stamping process, this paper demonstrates that it can also be applied in hydroforming. In a first phase experimental tests were carried out to form a part using this methodology, measuring the reduction in resulting thickness. It was found that difference between the calculated pressure and the experimental required pressure was 2.6%. To perform a numerical-experimental comparison, the simulation of the process was carried out using several material models by explicit finite element method in a commercial software. It was observed that using the material model HILL’90 deviation between experimental and numerical results for the thickness reduction was lower than 5.5%.

Equivalent Analogy Research on Filtration Resistance of Wet Fiber Layer for Mine Particles

The hypothesis of the flushing fluid that is evenly distributed and flowing on the surface of the wet filtering layer fiber was first introduced in the paper, on which the concept of equivalent diameter of the composite trap was given to build the theoretical model of filtration resistance of wet fiber layer for aerosol particles, therefore the theoretical formula of wet filtration resistance has been derived, making possible the theoretical research on the filtration and purification resistance of wet fiber layer for dust particles. Based on the theoretical analysis, a semi-theoretical and semi-empirical formula that can be applied to the practical use has been eventually obtained by means of the necessary dimensionless correction of the theoretical results through simulation experiments, the formula and the methods of research questions are of guiding significance and conductive to the filtration and purification of wet fiber layer for aerosol particles.

Analysis of the allowable deep drawing height of rectangular steel parts

This paper presents a theoretical, numerical and experimental analysis of the allowable (maximum) deep drawing height (DDH) of rectangular cups made of steel. In particular, a new expression to calculate the allowable DDH of rectangular deep drawing, based on the equivalent diameter concept and the volume conservation principle, is proposed and compared with those theoretical expressions currently available in the literature. Finite element method simulations together with experimental data taken from a set of 20 industrial steel parts are used to evaluate the accuracy of each theoretical expression. The results have shown that the new expression has superior precision than those existing in the literature.

Effects of particle diameter correction factor on the performance of cyclone collection efficiency models for an industrial application

A shape correction factor for flake-like particles is applied to six different previously reported models (Leith and Licht model, ideal laminar cyclonic flow model, ideal turbulent cyclonic flow model, mixed flow model, Zhang and Basu model, and Avci and Karagoz model) to calculate cyclone collection efficiency. The correction factor was obtained using an equivalent diameter concept based on particle volume and particle geometry. The results obtained after using this correction were compared to experimental data and it was found that the above mentioned models describe better the experimental collection efficiency data for particle diameters smaller than 20 μm in five of the six used models. Values for the D 50 were also calculated as well as their error compared to the experimental data. Error values for the D 50 calculation went from 77.8% to 7.7% for the Ideal laminar cyclonic flow model; from 92.9% to 70.3% for the Leith and Licht model, from 74.8% to 4.9% for the Mixed flow model; from 91% to 62.5% for the Avci and Karagoz model; from 87.7% to 48.6% for the Zhang and Basu model, and from 33.7% to 176% for the Ideal turbulent cyclonic flow model. These are promising results to predict collection efficiency more accurately for industrial processes that use cyclones.

Thermal conductivity of dielectric nanowires with different cross-section shapes

Non-equilibrium molecular dynamics simulations have been performed to investigate the effect of the cross-section shape on the thermal conductivity of argon nanowires. Some typical cross-section shapes, such as triangle, square, pentagon, hexagon and circle, are carefully explored. The simulation results show that with the same cross-sectional area of the regular polygons, the thermal conductivities decrease with the reduction of the sides of the polygons, and the thermal conductivity of the circular nanowire is larger than those of the other polygonal ones. Phonon gas kinetic theory is used to analyse the phonon transport in nanowires, and the concept of equivalent diameter is proposed to illustrate the characteristic dimension of the none-circular cross-section.

Concept of equivalent diameter for heat and fluid flow in porous media

In this note, we shall propose the concept of the equivalent diameter and the Reynolds number based on it, which can handle both hydrodynamic and heat-transfer aspects associated with fluid flow, and heat transfer in porous media. This concept enables us to extract a series of useful correlations for porous media, such as the friction factor, thermal dispersion and interfacial heat transfer coefficient, from existing correlations available for tube flows and cross flows over banks of cylinders. Prior to the discussion leading to the equivalent diameter, here we revisit the concept of the hydraulic diameter often introduced in conjunction with the Carman-Kozeny theory, to estimate the permeability of a fluid-saturated porous medium (See for example,). The hydraulic diameter dh may best be illustrated in consideration of a bundle of capillary tubes as shown in Figure 1, in which, Hagen-Poiseuille flow may develop. For each tube, the following equation should hold

Simulation of Fiber Deposition in Bronchial Airways

Penetration probabilities of inhaled man-made mineral fibers to reach central human airways were computed by a stochastic lung deposition model for different flow rates and equivalent diameters. Results indicate that even thick and long fibers can penetrate into the central airways at low flow rates. Deposition efficiencies and localized deposition patterns were then computed for man-made fibers with variable lengths in a three-dimensional physiologically realistic bifurcation model of the central human airways by computational fluid dynamics (CFD) techniques for characteristic breathing patterns. The results obtained for inspiratory flow conditions indicate that deposition efficiencies were highest for parallel orientation of the fibers, increasing with rising flow rate, branching angle, and fiber length at all orientations. Furthermore, deposition patterns were highly inhomogeneous and their localized distributions showed hot spots in the vicinity of the carinal ridge and at the inner sides of the daughter airways. Comparisons with other theoretical results demonstrate that the equivalent diameter concept, if including interception, presents a reasonable approximation for the parameter ranges employed in the present study.

Predicting the Collection Efficiency of Agglomerates in Fibrous Filters

Particle collection in fibrous filters is a very complex problem in filtration theory, and therefore spherical particles are mainly considered. Nevertheless, real particles often have a complicated structure, which influences their deposition behavior. The equivalent diameter concept can be used to account for non-sphericity. We predict the penetration of carbon agglomerates through fibrous filters using a model for spheres and suitable equivalent diameters for the agglomerates. In addition, penetration measurements were performed through a glass fiber filter and a non-woven stainless-steel wire filter. The measured penetrations agreed well with the calculations.

Reference Doses for Paediatrics from Fluoroscopic Procedures

The determination of reference doses for paediatrics is complicated both by the widely varying patient size, and the relatively small amount of data that has been collected. Dose-area product data has been collected for over five thousand paediatric patients from fifteen hospitals across the North of England, over a period of three years. The collection of data was facilitated by use of an automated data collection system. In order to make meaningful comparisons of the data, a method of correcting for patient size was formulated. This utilised the concept of equivalent diameter, which is determined from the patient height and weight. All dose-area product data was corrected to that for a standard size for each of five age bands. This enabled mean doses to be determined for each age band and examination type for comparatively large data samples. Third quartile levels were also determined for use as reference dose levels throughout the region.

Velocity distribution and skin friction resistance in rectangular ducts

This paper summarizes analytical and experimental findings about the characteristics of fully-developed flow in smooth-walled rectangular conduits. Results are presented which support the equivalent diameter concept for the single-parameter description of friction effects in turbulent conduit flow, including ducts of large aspect ratio.