Shape Of Column Research Articles

Application of multi-camera digital image correlation in the stability study of the long timber column with the circular cross-section under axial compression

Displacement meter synthesis (DMS), as a traditional method, is widely used to capture the local deformation of a specimen. However, for axis-symmetrical circular columns, the axial compression instability cannot be accurately evaluated using the DMS method due to the uncertain bending direction. To address this problem, a 360° full-surface digital image correlation (DIC) system composed of eight cameras is proposed to capture the full-field deformation information of the column surfaces under axial compression. The objective of this study was to experimentally validate the efficiency of the proposed novel measurement in tracking the full-filled compressive deformation of a long wooden column with the circular cross-section. The test results showed that the columns experience instable failure. The multi-camera DIC system can completely reconstruct the three-dimensional shape of the circular column and obtain the whole process deformation state at any position on the surface of the timber column. The DIC method also can capture the uncertain lateral deformation direction and obtain the data of lateral deflection at the mid-span of timber columns. The multi-camera DIC provides an intuitive and comprehensive new test method for the test and analysis of the stability of axisymmetric long timber columns.

Effect of nozzle inlet swirl and air column shape in nozzle on water jet occurring periodic droplets splashing

Water with free surface inside the water tank was pressurized and ejected as a water jet from nozzle with abrupt contraction flow path attached to the bottom of the tank. When the height of the free surface of water makes low into some height from the bottom of the tank, a peculiar air column is generated in the nozzle, a phenomenon occurs in which the droplets are periodically aligned outward in the radial direction and are rapidly splashed from the jet due to the pressure difference from the atmospheric pressure. In order to investigate how water swirling near the nozzle inlet affects this droplet splashing phenomenon, The bottom of the tank was designed to affect the flow of water, and the flow of water was analyzed using visualization photography. As a result, it was found that the circumferential velocity has a great influence on the droplet splashing phenomenon under low pressure. When the circumferential velocity increases, it affects the shape of the air column in the large tube of nozzle, and the shape makes it easier for air bubbles to be generated in the small tube of nozzle. It was found that these processes facilitated the occurrence of the droplet splashing phenomenon.

1層1スパンの鉄骨構造物を対象とした梁端部の剛性低下が固有振動数と柱の固有モード形状に及ぼす影響

In this paper, the effects of reduced rigidity at the beam end on natural frequency and mode shape of column for steel structure made clear 3 aspects.

Optimization of Fiber-Reinforced Polymer Bars for Reinforced Concrete Column Using Nonlinear Finite Element Algorithms

The ductility and strength of reinforced concrete (RC) columns could be noticeably improved by replacing steel bars with polymeric bars. Despite the previous research on RC columns, most of those studies focused only on the lateral load capacity of this structural member and were mainly costly experimental studies. However, this paper is concentrated on the previously occurred damages to the reinforced columns in the previous earthquakes. Subsequently, finite element analysis has been performed to examine 24 models including the various shapes of RC columns. In employing the plastic behavior of steel, carbon fiber-reinforced polymer (CFRP), and glass fiber reinforced polymer (GFRP) bars, the bilinear hardening has been considered. To capture both compressive and tensile behavior of the concrete, the concrete damage plasticity model has been implemented. Furthermore, the optimization technique is used for CFRP models to compare with other models. In this paper, the parameters of energy, seismic factor, stiffness, and ductility have been computed using the method proposed by the authors. This suggested method is considered to compare the results from each parameter. Finite element results of steel bars are compared with carbon and glass models. The results show the stiffness of models is improved by CFRP bars, while the energy absorption and ductility factor are enhanced with steel bars. Moreover, GFRP bars can enhance the seismic factor. The reduction of column stiffness to almost half would occur in some rectangular cross-section columns.

ANALYSIS OF THE STATION OF TOPIARY FIGURES ON THE TERITORI OF THE VINNYTSIA NATIONAL AGRARIAN UNIVERSITY

The article examines the relevance of topiary art in modern landscape design. The art of topiary requires a well-thought-out compositional integrity. Before choosing plants, you should decide on the theme of the garden and the harmonious arrangement of topiary figures in it. Such compositions become an adornment of any backyard territory, giving it an aristocratic exclusivity and originality. A detailed taxonomic analysis of the assortment of plants, which were used to form topiary on the territory of Vinnytsia National Agrarian University and the botanical garden "Podillya", was carried out. The state of the existing topiary figures was assessed. The features of the formation of topiary figures by the classical and wireframe formation technique have been investigated. Of the plants of the classical formation technique, a spiral figure has an excellent appearance. The hedge, cone and column shape have a good appearance. Plants formed in the form of a circle have the lowest indicators of external perception. The frame technique for creating plant compositions prevails at the VNAU exposition area. Project proposals have been developed to improve the aesthetics and general appearance of topiary figures on the territory of the Vinnytsia National Agrarian University. For the plant to have an attractive appearance, appropriate care is needed. Pruning of plants (sanitary) should be carried out only during the dormant period. The best period will be the end of winter, when the threat of severe frosts has passed. In the spring, no later than the first half of April, the first corrective pruning of figures and hedges should be carried out. In the summer, several additional haircuts are made, the frequency of which depends on the intensity of growth. It is optimal to carry out an additional haircut 3 months after the first one. In summer, you do not need to cut in extreme heat. Haircuts are finished before the onset of the first frost. If you carry out the formation later, then the created topiary will simply freeze over. In the cold season, some figures, especially those created from conifers, can fall apart under the weight of snow, so it is advisable to tie them up.

Thermal and hydraulic analysis of ultra-thin vapor chamber with copper columns considering Marangoni effect

The ultra-thin vapor chamber (UTVC) technology offers an attractive approach for thermal management of micro devices due to tiny volume, flat contact area and high temperature uniformity. In this paper, a 3D transient numerical model of UTVC is established to study the performance of the UTVC. The numerical method takes into account the variation of saturation pressure with saturation temperature. The Marangoni effect on the evaporation process is also discussed in wick microstructure. The modified boundary conditions are proposed to couple Marangoni effect on the liquid flow and pressure drop. According to the modified numerical method, the transient characteristics of UTVC are analyzed. The numerical results have excellent agreement with the experimental results and the maximum relative error is less than 1%. The numerical analysis result shows that the UTVC has rapid transient thermal response time and the time for UTVC to reach the steady state was less than 60 s at three heat loads. The pressure drop of UTVC is mainly in the vapor region, but the pressure drop of liquid increases by 12% after considering Marangoni effect. Comparing different copper column models, the increase of rows can increase the overall pressure drop of UTVC; but it can also improve the temperature uniformity of heating area and slightly reduce the overall thermal resistance before capillary limit is reached. The shape of copper column has little effect on the thermal performance of UTVC, while the influence of pressure drop is circular < diamond < square. These results provide valuable suggestions in design of copper columns to decrease pressure drop and improve thermal performance of UTVC.

Experimental Investigation on Concrete Filled Steel Tube Columns under Concentric and Eccentric Loading

Modern construction projects such as skyscrapers, bridge with a large span, residential structures, towers for transmission, warehouses and other industrial structures have all incorporated concrete-filled steel tube (CFST) columns. Fire resistance, excellent ductility and high bearing capacity are all the advantages of CFST columns. Among the different shapes of CFST columns, uses of rectangular and square CFST columns are becoming more favored in modern construction projects for their simple beam-to-column connections design. This study tested 10 concentrically loaded CFST columns and 8 eccentrically loaded CFST columns. One of the most effective techniques to delay local buckling and enhance the ultimate strength of the CFST columns is to use longitudinal inner stiffeners on these steel tubes. Cold-formed steel tube sections are vulnerable due to local buckling; however, a concrete core is able to restrict such early local buckling in the cold-formed steel tube. The test specimens consisted of unstiffened sections and longitudinal inner-stiffened sections. In total, the experimental program tested 18 CFST stub columns with both compact and slender sections, without longitudinal stiffener, with 2 longitudinal inner stiffeners and with 4 longitudinal stiffeners. The test strengths have been as compared with predictions based on the existing design code AISC 360-16 for calculating the ultimate capacities of the CFST stub columns subjected to both concentric and eccentric loading. The focus was mainly on the effect of vertical stiffener square concrete-filled steel tubes on the overall concentric and eccentric compression capacity. The results identified that the longitudinal inner stiffeners had a significant impact on the ultimate strength, deformability and mode of failure in the CFST stub columns. To prevent local buckling of such steel tube, a longitudinal inner stiffener could be applied. In addition, the compression capacity was increased by 12–13.5%.

Closed-form solution for optimization of buckling column

The optimization problem for a column, loaded by compression forces is studied in this article. The direction of the applied forces coincides until buckling moment with the axis of the column. The critical values of buckling are equal among all competitive designs of the columns. The dimensional analysis eases the mathematical technique for the optimization problem. The dimensional analysis introduces two dimensionless factors, one for the total material volume and one for the total stiffness of the columns. With the method of dimensional analysis, the solution of the nonlinear algebraic equations for the Lagrange multiplier will be superfluous. The closed-form solutions for Sturm-Liouville and mixed types boundary conditions are derived. The solutions are expressed in terms of the higher transcendental functions. The principal results are the closed-form solution in terms of the hypergeometric and elliptic functions, the analysis of single- and bimodal regimes, and the exact bounds for the masses of the optimal columns. The isoperimetric inequality was formulated as the strict inequality sign, because the optimal solution could not be attained for any finite seting of the design parameter. The additional restriction on the minimal area of the cross-section regularizes the optimization problem and leads to the definite attainable shape of the optimal column.

Magnetohydrodynamics radiative dissipative slip flow of hydrogen-oxide (H2O) infused with various shape tungsten, tin, titanium (nanometer) particles over a nonlinear radial stretching surface

Optimal control over heat transfer during the manufacturing of various significant cylindrical components is vital to achieving a desirable finished product. Insertion of various-shaped nanoparticles provides a promising solution to the problem at hand due to their greater thermal conductivity and unique features. Keeping in view, the present article is an effort to explore the slip flow of hydrogen-oxide [Formula: see text] infused with lamina- and column-shaped tungsten, tin, and titanium nanometer-sized particles over a nonlinear radially stretching surface. The physical model is presented by utilizing the fundamental laws of mass, momentum, and energy conservation. Magnetohydrodynamics, thermal radiation, and viscous dissipation effects are incorporated to provide physically realistic analysis. Utilizing scaling analysis flow governing problem is converted into a set of higher-order nonlinear Ordinary differential equation’s which afterward are tackled numerically. Quantities of practical significance such as surface friction and heat flux are portrayed through bar graphs and are examined physically in a detailed manner. Column shape tungsten nanoparticles offered minimum surface drag with the highest heat transfer rate compared to the other two particles making them an optimal choice in manufacturing cylindrical components as per our study.

FEM-PGD BASED TECHNIQUE FOR COLUMN SHAPE OPTIMIZATION AGAINST BUCKLING

This paper presents a simple numerical procedure based upon the projected gradient descent (PGD) and finite element method (FEM) for the shape optimization of laterally restrained columns to attain the maximum elastic buckling load under the specified volumetric constraint. The analysis of the buckling load is achieved via the formulation based on Euler-Bernoulli beam theory, the discretization by the standard finite element technique, and the determination of the least eigenvalue and the corresponding eigenvector via the power method with Rayleigh quotient. In the optimization, the profile of the cross-sectional area of the column is represented by piecewise polynomial interpolation functions. The gradient information and the projection operator required in PGD iterations are obtained explicitly in a closed form. A selected set of results is reported to demonstrate not only the good convergence behavior and accuracy of numerical solutions, but also the capability of the proposed technique to attain the optimal shape of columns for various scenarios.

Numerical simulation study of thermal and hydraulic characteristics of laminar flow in microchannel heat sink with water droplet cavities and different rib columns

Microchannel heat sink is an effective technology to dissipate heat for high flux density devices. However, it is still unknown that what geometric structure form of channel will most effectively improve the overall performance of microchannel heat sinks. Three-dimensional numerical simulations were carried out to investigate the flow and heat transfer characteristics of microchannel heat sinks designed with an innovative combination of water droplet cavities and rib columns. Five different shaped rib columns were considered, including triangular, rectangular, diamond, elliptical and trapezoidal rib columns. A comparative analysis was presented to discuss the performance of these geometric configurations according to average Nusselt number (Nu), friction coefficient (f), entropy production (SΔ) and overall performance factor (η). It was found that the combination of water droplet cavities and rib columns can greatly improve the overall performance of microchannel heat sinks due to the full use of the advantage of rib columns to enhance heat transfer with the strengthened fluid flow disturbance and the advantage of cavities to reduce pressure drop with the enlarged flow area. The rib column shape and geometric parameters have significant effect on hydrothermal performance. Furthermore, the microchannel with water droplet cavities and elliptical rib columns has the best overall performance in all the cases and its overall performance factor achieves up to 1.513 with α = 0.3 and ξ = 0.5 at Re = 331.32.

Study on Dominant Parameters Determining Streamer Initiation From Hydrometeors in Thundercloud Fields

AbstractThis study reports a study trying to find the dominant factor on streamer initiation from an isolated hydrometeor in thundercloud fields at 7 km altitude corresponding to an atmosphere pressure of about 0.453 atm. Three parameters are considered including hydrometeor size, shape, and electric quantity. The simulation results indicate that a larger hydrometeor is more likely to initiate a streamer discharge at a lower ambient field for noncharged hydrometeors. The charge on hydrometeor plays a prominent role when a charged hydrometeor has a smaller size, and it is easier to initiate a streamer in this case. At 0.25 Ek, a positive streamer discharge has been presented for a charged hydrometeor with a radius of 0.5 mm. The critical field to form streamer discharge for a column shape hydrometeor without charge is much smaller than that for a spherical hydrometeor. If smaller hydrometeors are charged, the critical field for a spherical hydrometeor becomes lower than that for a column one. The electric quantity charged on hydrometeor has little effect on the critical field for both spherical and column hydrometeors, when the hydrometeor size is larger enough. The charge on hydrometeor plays a dominant role in streamer initiation when hydrometeor is smaller, but hydrometeor shape becomes more important for larger hydrometeor. Streamer discharge can be predicted by Meek number, but stable streamer cannot be ensured. Streamer branch will be met when ambient field is lower than 0.25 Ek.

Band broadening in mobility shift affinity capillary electrophoresis due to pressure-driven flow

Mobility Shift Affinity Capillary Electrophoresis (msACE) presents a simple and powerful approach to determining the equilibrium and kinetic parameters governing the interaction between a variety of analyte and ligand molecules. These determinations often rely on measuring the elution peak profile for the analyte zone when migrated with a steady electric field. However, pressure-gradients applied intentionally or generated due to unwanted differences in the hydrostatic heads at the capillary/channel ends and/or a variation in the electroosmotic flow rate along the analysis column can significantly alter this peak profile introducing error in the estimated parameter values. To account for these alterations, this article describes a mathematical formulation for quantitating band broadening in msACE systems due to a steady pressure-driven flow in the Taylor–Aris dispersion limit with fast analyte-ligand binding kinetics. The current analysis shows that the additional zone dispersion under such conditions can be quantitated using four terms that scale with the square of the Péclet number calculated based on the pressure-driven flow velocity. While the first term among these quantitates the Taylor–Aris dispersion experienced by a neutral tracer advected by the pressure-gradient, the other three terms are proportional to the square of the difference in the diffusion coefficients for the analyte and analyte-ligand complex. Moreover, these latter terms also vary inversely with the Damköhler number computed as the ratio of the rate of reaction over that of diffusive mass transfer with the coefficient for each of the four terms shown to be dependent on the cross-sectional shape of the analysis column.

Essential mineral content variations in commercial marine species induced by ecological and taxonomical attributes

Seafood is one of the most traded food commodities and its consumption is highly recommended since it is an excellent source of minerals for humans. This work reports the essential mineral content of 96 marine species from the Northeast Atlantic and clarifies how taxonomical and ecological attributes (i.e. feeding mode and vertical distribution in the water column) shape their mineral composition. In general, potassium (296 to 5410 mg kg−1 ww), phosphorus (645–4500 mg kg−1 ww), and sodium (230–7410 mg kg−1 ww) were the most abundant macrominerals, while zinc (2.1–1670 mg kg−1 ww), iron (0.92–468 mg kg−1 ww), and copper (0.061–318 mg kg−1 ww) were the most abundant microminerals in the species studied. Differences in the mineral content of taxonomic, feeding mode, and vertical distribution groups were found, which were attributed to a combination of specific characteristics and physiological requirements, diet composition and bioavailability of minerals in the surrounding environment (water and sediments). Element-dense groups were also identified according to their mineral content, which can enable better informed choices regarding human nutrition.

Optimization of grouting method and axial performance of pressure-grouted helical piles

Pressure-grouted helical pile (PGHP) is an innovative piling system that allows a significant increase in helical pile capacity with relatively low additional cost. The pile is constructed by applying pressurized grout during the installation of conventional helical piles. The grout is injected into the ground through two nozzles welded to the hollow pile shaft. This paper presents a comprehensive laboratory study to investigate the effect of three different nozzle configurations on the shape and axial performance of PGHP. The results reveal a significant increase in the PGHP shaft resistance over that of the un-grouted helical pile due to the formation of a continuous grout column with a larger diameter, higher friction angle at the pile–soil interface, and higher lateral earth pressure around the pile. The shape and diameter of the grout column created depend on the nozzle configuration used for grout injection. An increase in the end-bearing resistance is observed due to grout dissipation into the supporting soil voids. The study also shows that PGHPs installed with the third nozzle configuration have the fastest installation rate and the highest compression and pullout resistances. Thus, the third nozzle configuration is recommended for PGHP construction.

Influence of Load Plates Diameters, Shapes of Columns and Columns Spacing on Results of Load Plate Tests of Columns Formed by Dynamic Replacement.

The dynamic replacement method is used to strengthen the subgrade of objects, usually up to 5 to 6 m thick. After the improvement process, acceptance tests in the form of load testing are carried out. Interpretation of the test results can cause some difficulties. Dynamic replacement results in a situation where columns of different shapes, loaded with plates of diameters usually smaller than the head diameter and in the vicinity of adjacent columns, are subjected to load tests. In order to demonstrate the influence of these factors, a spatial model of soil strengthened by dynamic replacement, comprising four material zones, was calibrated on the basis of load testing. The following models were used in the analysis: linear-elastic, elastic–perfectly plastic (Coulomb–Mohr) and elastic–plastic with isotropic hardening (Modified Cam-Clay). This formed the basis for 105 numerical models, which took into account the actual shapes of the columns made at various spacings, subjected to load tests with plates of various diameters. The analyses of the settlements, calculated moduli and stress distribution in the loaded system showed how the results were significantly influenced by mentioned factors. This implies that the interpretation of the results of load tests should be based on advanced spatial numerical analyses, using appropriate constitutive models and including the considered factors.

What causes AIS? Ask the genome!

The most common developmental disorder of the spine is scoliosis, a rotated, lateral deformity in the shape of the spinal column. Scoliosis may be part of the clinical spectrum that is observed in many developmental disorders, but typically presents as an isolated symptom in otherwise healthy adolescent children. Adolescent idiopathic scoliosis (AIS) has defied pathogenic understanding in part due to its genetic complexity, and to the lack of well-defined animal models. The disease is also remarkable in its sexual dimorphism, where girls are at more than five times greater risk of progressive deformity than boys. Breakthroughs have come from recent genome wide association studies (GWAS) and next generation sequencing (NGS) of human AIS cohorts. Post-hoc gene set and pathway-level analyses of genetic datasets have highlighted a role for cartilage biogenesis and the development of the intervertebral disc (IVD) in disease susceptibility. Moreover, next generation sequencing in AIS families, as well as modeling in vertebrate systems, has revealed that rare deficiencies in proteins of the cartilaginous extracellular matrix (ECM) collectively contribute to AIS. Thus, as in a jigsaw puzzle, the pieces coming together from multiple biologic studies suggest that deficiencies in the structural integrity and homeostasis of spinal cartilages are culprits in AIS susceptibility. Here, we update progress in understanding the genetic, biochemical, and cellular determinants of AIS. We also suggest a molecular model in which interaction of the hormonal environment with genetic susceptibility may increase risk of this common disorder of childhood.

A theoretical model for estimating the water-tightness of jet-grouted cut-off walls with geometric imperfections

Jet-grouted columns are commonly used to form cut-off walls in various water-seal project applications. However, affected by geological conditions or other factors, the geometric shapes of jet-grouted columns often deviate from the design values, which affects the water-tightness of cut-off walls. The probability distributions of factors inducing geometric defects in the cut-off walls are analyzed first according to field testing to estimate the water-tightness of jet-grouted cut-off walls with geometric imperfections. Based on this, three-dimensional simulation models of jet-grouted cut-off walls considering geometric defects are established. A simplified theoretical soil seepage model with a cut-off wall is deduced based on Darcy's law. The geometrical parameters in the simulation model are related to the cut-off thickness in the simplified theoretical model according to the equal seepage flow, and a theoretical model of a jet-grouted cut-off wall considering defects is obtained. Finally, the theoretical model is verified by numerical simulation and field observation, and it is found that the theoretical model can get reliable calculation results. This theoretical model can provide a basis for the parametric design of jet-grouted columns and can also predict the degree of seepage flow before soil excavation.

CFD study of oscillatory motion effect on liquid flow distribution into structured packed divided wall column

Packed distillation columns are key equipment in natural gas pre-treatment process within LNG production process train operated at offshore. In this work, the impact of offshore operating conditions and that of divided wall column shape were explored via developing transient three-dimensional CFD model for a divided wall distillation column filled with structured packing. Inter-phase drag force, porous resistance force, mass transfer, and liquid dispersion were incorporated into volume averaged equations to map the distortion in liquid distribution in response to column oscillatory motion. The results show that introducing a dividing-wall into distillation column affects fluids partition and distribution. Column motions induce complex fluid flows in radial direction that result in oscillatory patterns around the steady-state solution of vertical column. Furthermore, liquid distributions in a divided wall column under influence of column motion differ with respect to column system positions throughout rotational axes, mass transfer also fluctuates according to column oscillations. A position with a dividing wall making an angle of 45˚ with rotational axis gives a scenario in which rolling motion resembles to pitching motion. The thereof position leads to moderate liquid maldistribution in comparison to liquid maldistribution from scenario with dividing wall parallel to rotational axis.

Punching Strength of Reactive Powder Reinforced Concrete Flat Slabs

This research is devoted to investigating experimentally the punching shear strength of reactive powder concrete slabs under monotonic loading. All slabs have the same flexural reinforcement and same dimensions (1000mm length,600mm width,50mm thickness). The experimental program includes casting and testing of sixteen slabs tested under monotonic loading. The major parameters adopted in the current research include the shape of column (circle, square), column size (twocolumn sizes), number of columns (one, two), and the distance between two columns (3d,5d,7d). Results showed that, the slabs with circular column sections have slightly higher ultimate load than those with square column sections. An increasing column area increases the load of punching shear failure. It was found that the ultimate failure load for slabs with two columns is greater than the slabs with one column. Related to the effect of distance between the two columns for monotonic, it was found that the slabs maximum load reaches the maximum value at distance between the two columns equal to(7d) for a circular section with a diameter of 85mm and 113mm and square section with dimensions of (100*100)mm. While the maximum failure load reaches the maximum value when the distance between two columns (d) for a square section with the dimension of (75*75)mm. Related to the crack patterns, it was noticed that for slabs with larger columns sections with the distance between columns equal to 7d, the failure zone extended (in a large direction) to the slab sides.