Tube Dimensions Research Articles

Phase equilibrium and micronization for flufenamic acid with supercritical carbon dioxide

Abstract The solubility data of flufenamic acid (FFA, a fluorinated and non-steroidal anti-inflammatory drug) in supercritical carbon dioxide were measured with a semi-flow type phase equilibrium apparatus at temperatures from 313.2 K to 333.2 K and pressures up to 21 MPa. Over the experimental conditions, the solubility values are between 0.8 × 10−6 and 2.13 × 10−4 in mole fraction. These solid–gas equilibrium data were correlated with the Chrastil model, Mendez-Santiago and Teja model, and the Peng–Robinson equation of state to average absolute relative deviations of 11.4%, 21.1%, and 7.8%, respectively. Since the solubility of FFA can be as high as 10−4, rapid expansion of supercritical solution (RESS) method is favorable for preparing ultra-fine FFA particles. The experimental results of the RESS micronization show that extraction pressure, pre-expansion temperature, and dimension of capillary tube are the key factors to govern the morphology and the mean size of the resultant particles. While sticky agglomerates were obtained from lower extraction pressures with larger and/or longer capillary tube, needle-like particles were produced at higher extraction pressures with smaller and/or shorter capillary tube. Moreover, operating at lower pre-expansion temperatures and higher crystallization temperatures yielded longer and thinner needle-like crystals. Under higher extraction pressure (e.g., 21 MPa), the mean size of the generated FFA particles distributed from 0.5 to 5.1 µm and from 0.1 to 1.1 µm for the lengths of major and minor axes, respectively. It is also found that the particulate FFA converts from original form I into form III after the RESS processing.

The Inner Flow and Heat Transfer Analysis of Round Tube with Different Rotating Speed

Aiming at the inner flowing characteristics of round tube, the different transient cases of tube with rotating wall boundary are analyzed by CFD, and the six cases are determined according to the different rotating speed respectively. The fluid is water, with the same dimension of tubes, the negative pressure region moves forward in the tube as the increase of rotating speed, and the outflow velocity is high to 31.42 mm/s, being 348.22% more than that of steady case. When the rotating speed is 1 rev./s, there is a lowest temperature band between the wall and center high temperature flow. In the transient temperature analysis, the high temperature cloud changes to cone-like shape, and there is a swirl with lower temperature at the inlet part with a large depth into the tube center. The case with 2 rev./s has the much more uniform temperature distribution than others.

맨드렐을 이용한 엘보우 성형 공정해석

In this study, process analysis of elbow-shaped tubes using a mandrel has been performed. To reach the final shape within the dimensional tolerance, the process analysis has been performed at various processing parameters such as tube dimensions, the curved cutting surface and the radius of curvature. The area outside the boundary of the target shape was expressed as a quantitative index to analyze the formability. The validation experiments have also been performed in order to increase the reliability of the process analysis. For the processing of elbow-shaped tubes, it is preferable to make the angle of the portion where the punch touches the tube smaller than the opposite angle. And the convex cutting surface is advantageous due to the increased contacts between the punch and the tube ends during the bending process. Elbow tube having larger radius of curvature shows higher dimensional accuracy due to the relatively uniform strain distribution.

Viscous behavior of synthetic silica glass tubes during collapsing

The viscous behavior of synthetic silica tubes is studied during collapsing. This technique can be applied directly during the modified chemical vapor deposition (MCVD) of light-guiding preform preparation. By performing several experiments with different tube dimensions, the material viscosity can be measured. In addition, information concerning the thermal behavior of the glass tubes during this process (the difference between the outer and inner temperature depending on the process conditions) can be derived, which is important for process control. This MCVD-inherent temperature difference is caused by radiation loss in wavelength regions in which quartz glass is semitransparent.

Physical and Numerical Modelling of Laser Dieless Drawing Process of Tubes from Magnesium Alloy

Abstract This paper is devoted to the development of technological process of production of magnesium alloy tubes by laser dieless drawing process. The purpose of the paper is the development and verification of the FEM code for simulation of LDD process and the study of main regularities of this process for magnesium alloy tubes. The problems of forecasting the geometric dimensions of the tube and the possibility of the crack of the material were considered.. The developed FEM code takes into account the three-dimensional deformation of the material, thermal processes, laser heating, the mechanical properties of the material and process parameters. Calibration of the model included the definition of the absorption coefficient, which determines the efficiency of laser heating. For this purpose the experimental analysis of the temperature distribution during the process was made. In laboratory conditions the experiment of laser dieless drawing of tube from AZ31 alloy was performed with the initial outside diameter of 5 mm and a wall thickness of 1 mm. In the experiment the tube surface was covered with a graphite paint to increase the absorption coefficient. The value of absorption coefficient was determined by the inverse analysis and was equal to 0.12. The calculated results were used for producing tube in laboratory. As a result, a good correspondence of geometrical dimensions of the final tube with the calculated values was achieved.

Quantitative relationship between fluid inhomogeneities and flow enhancement in nanotubes.

Flow enhancement in nanotubes is of great potential to achieve ultra-fast fluidic transport. However, the mechanism of such a fast transport and the reduction as the tube enlarges to bulk scale is still unclear. In this study, we establish a model to quantitatively correlate the flow enhancement and the fluid inhomogeneity to describe the enhanced transport and its evolution with the tube dimension. We found the fluid inhomogeneity at the solid-liquid interface in nanotubes and its independence with tube size by dissipative particle dynamics (DPD) simulation. Based on that, we establish novel theoretical models for the penetration rate in nanotubes for the first time with parameters related to the fluid inhomogeneity which can achieve quantitative prediction of nanoflow enhancement and are valid through all scales.

Axisymmetric irrotational potential flows of an ideal fluid in doubly connected domains

Amethod of constructing the model of ideal incompressible unbounded flow past an axisymmetric tube is developed; the tube shape and dimensions are determined in the process of the problem solution. The problem is solved using the method of spatial annular sources and sinks. It is shown that under certain conditions the resulting flow corresponds to that past a round finite-length tube, whose wall has a finite thickness. It is established that near the tunnel entry the flow is considerably restructured.

On numerical modelling of multi-rifled tube drawing

Abstract Production of precision seamless steel tubes in Zeleziarne Podbrezova is divided into several technological steps, with final cold drawing determining final tube dimensions. The drawing itself usually takes several drawing passes with intermediate heat treatment. For multi-rifled tubes, the last drawing pass utilizes a special, free-to-rotate plug with multiple helical grooving so to produce a helical rifling pattern on the inner surface of the tube. A crucial factor to meet stringent dimensional tolerances on rifling geometry is to determine proper input dimensions of the tube just before the final rifling pass. Also, drawing velocity is another key factor that not only determines the overall productivity but the quality of the rifling as well. Due to the high costs of plant trials in early stage of technology development, computer simulation approach can easily serve the purpose very well, thus saving us from laborious and costly pilot experiments. Numerical modelling software DEFORM-3D has been utilized in Zeleziarne Podbrezova for drawing technology development and optimization for T12 steel tubes with 28.6 × 6.3 mm (O.D. × W.T.) In particular, both input dimensions and drawing velocity were optimized while meeting rather strict dimensional requirements on tube rifling. Resulting tube & rifling dimensions were in good accordance with dimensions from experimental proofing trials, where the actual dimensions were obtained via 3D optical scanning of multi-rifled tubular samples.

M2 macrophages contribute to osteogenesis and angiogenesis on nanotubular TiO2 surfaces.

The monocyte/macrophage system plays an essential role in the host response and the fate of endosseous implanted materials. Macrophage behavior was thought to be regulated by nanostructured titanium which has been considered as a very promising candidate for dental implants. However, there is little known for subsequent effects of these activated macrophages on osteogenesis and angiogenesis which were essential for bone integration. Here we presented two different dimensions of titanium nanotubes generated by anodic oxidation at 10 V (NT 10) and 20 V (NT 20), respectively. The behavior of macrophages on the surfaces was evaluated, and their conditioned medium (CM) was collected to stimulate MC3T3 and HUVECs, with commercially pure titanium (cp Ti) as control. We found that NT 20 induced macrophage activation similar to the anti-inflammatory M2 macrophage state with the enhanced expression of IL-10 and ARG, while NT 10 was associated with M1 macrophage phenotype characterized by high levels of IL-1β, iNOS and TNF-α. Furthermore, the osteogenic capacity of MC3T3 in CM from NT 20 was enhanced (NT 20 > NT 10 ≈ cp Ti) and the tube formation capacity of HUVECs was promoted in CM from nanotubular surfaces with increasing tube dimensions (NT 20 > NT 10 > cp Ti). Our data suggest that dental implants with the large nanotube dimension surface could result in a favorable osteoimmunomodulatory microenvironment for the establishment of osseointegration.

Enhancement of laser intensity and proton acceleration using micro-tube plasma lens targets

A hollow, cylindrical, micron-scale structure is proposed to enhance and manipulate the laser plasma interaction. It is shown through 3-D particle-in-cell simulations that the incident laser pulse intensity is enhanced within the tube. A detailed study of the intensification optimizes the tube dimensions and provides a characterization of the in-tube intensity. By coupling the micro-tube plasma lens to a traditional flat interface, we show an increase in on-target intensity. We detail proton energy enhancement as a potential application of the micro-tube plasma lens target, where the tube structure focuses the light and provides additional electrons that enhance the accelerating sheath field.

Is the gut content ofMilnesium(Eutardigrada) related to buccal tube size?

Milnesium, with its relatively short and wide buccal tube, is considered carnivorous. Species in this genus exhibit differences in buccal tube length, standard buccal tube width, and the buccal tube length/width ratio. To determine whether buccal tube size is correlated with the type of prey, ˜4000 specimens of various Milnesium species were examined. Among those with identifiable gut contents, ˜97% contained tardigrades, rotifers, or both, whereas only ˜3% contained nematodes or amoebas. In total, 189 females with guts containing only tardigrades, only rotifers, or both were analysed with general linear model multivariate analysis. Milnesium specimens containing only tardigrade remnants were larger and had longer and wider buccal tubes than those containing only rotifers. Those with only tardigrades in the gut also had a significantly lower buccal tube length to width ratio than those with only rotifers in the gut. Specimens with a mixed diet (rotifers and tardigrades) had intermediate values of buccal tube width and length, and these differed significantly from individuals containing rotifers or tardigrades only. Variation in buccal tube dimensions was linked with interspecific and age (size)-related factors, and differences in buccal tube dimensions associated with gut content remained significant, even when the analysis was controlled for the interspecific variation. No evidence of cannibalism was observed.

Numerical analysis of tube expansion process for heat exchangers production

This work analyses two different aspects of the mechanical process of tubes expansion used for the production of heat exchangers. In particular, the influences on the expansion process due to mandrel geometry and geometrical errors in tubes, caused by production tolerances, were studied and analyzed using finite element (FE) models. A 2D axisymmetric model was used to study the influence of mandrel geometry, whereas a 3D solid model was adopted to investigate the influence of geometrical errors in tubes. Experimental tests were carried out on actual materials in order to set up and validate the FE models. Force required for expansion, and variation in tube dimensions due to expansion were investigated and a good agreement was found between experimental and FE results. Additionally, the obtained results showed that the fillet radius is the most important geometrical factor of the mandrel in order to reduce the expansion force. A great influence of the tube geometrical errors was observed on the tube expansion process, which can compromise the performance of the heat exchanger. Finally, it is worth mentioning that the present study provides useful information that might be used to improve tubes expansion processes in general and heat exchangers production in particular.

Calculating scale tunings of Polynesian nose flutes

The Polynesian nose flute is found in two versions that are blown in a similar manner but fingered and tuned differently. The Eastern Polynesian flute, known in Hawai'i as 'ohe hano ihu, but is found also to Tahiti and Niue. The tube is closed by a segment node at one end but with a hole for blowing and open at the other end. It typically has two or three finger holes along the tube and three or four playable notes. Being similar to other flutes, the scale tunings can be calculated from hole and tube dimensions by analytic expressions. In Fiji, New Zealand, Samoa, and Tonga, where it is known as fangufangu, both ends of the Western Polynesian flute are closed by segment nodes. There are five holes are placed along the top, usually evenly spaced from one end to the other, with a sixth hole in the middle underneath, giving a variety of fingering options with four to six notes and two registers. The scale tunings are determined by first calculating the frequency response using a lumped-element method.

Influence of Die Geometry on Drawing Force in Cold Drawing of Steel Tubes Using Numerical Simulation

In Železiarne Podbrezová, cold drawing process is the final process in production of precision seamless steel tubes. This particular technology utilizes multiple drawing sequences and intermediate annealing. From the physical point of view, it is nothing just the optimal use of plastic deformation during cold forming that grants the final tube dimensions. The drawing process itself is significantly affected by physical and metallurgical properties of the tube, the tool geometry, the lubrication, and the sequence of operations. This paper deals with the relationship between the tool geometry and the drawing force. The FEM-based numerical model of the process was prepared in DEFORM 3D in order to optimize the geometry of the die; eight die geometries were investigated in total. The numerical simulation itself considered a hot rolled hollow at Ø32 mm × 4 mm, cold drawn into Ø25 mm × 4 mm using die drawing (sinking) sequences only. Calculated drawing force showed that the change of the run-in angle of the die led to a decrease of the drawing force.

Basic Analysis of the Incremental Profile Forming Process

Increasing demands in profile manufacturing leads to a constant increase of the geometric complexity of the profile. Nowadays, lightweight design and load adaption are of huge importance and a need for new profile manufacturing technologies exists. In order to cope with this development, a new tube profile forming method was invented, the incremental profile forming (IPF). IPF allows the flexible manufacturing of profiles with varying cross section geometries along the longitudinal profile axis and offers therefore a high potential for the manufacturing of lightweight design parts. Due to the high degree of innovation, research work regarding the process fundamentals as well as the process limits is necessary. For this reason, the results of the first basic experimental and numerical investigations are presented. While in the experiments, the potential of the process is shown in feasibility studies, first analyses of the forming process, and the influence of different process parameters on the process were carried out in numerical investigations. In particular, it turned out that the tool infeed and tube dimensions have significant influence on the forming force, whereas the tool radius has a minor influence.

Experimental Performance Comparison of R134a and R600a Refrigerants in Vapour Compression Refrigeration System at Steady State Condition

This paper focuses on the performance comparison and analysis of refrigerants used in domestic compression refrigeration systems in the premises of steady state.R134a and R600a are the two refrigerants considered for comparison. Refrigerators used for domestic as well as household uses were chosen for conducting the experiments. The achieved results show that 50g of R600a produces the same output as produced by R134a.Based on the results, R600a performance compressor coefficient, charge amount and condenser evaporator were chosen for the analytical design. Out of the various outcomes, the variance result supported the view that R600a charge amount was the most notable parameter. At conditions which are optimal the charging amount necessary for R600a was found to be 60g which was 68% lesser than R134a.Other working parameters include heat transfer performance and capillary tube dimensions. Comparison and review results show that R600a performs better than R134a.

Residual stresses evolution in Cu tubes, cold drawn with tilted dies – Neutron diffraction measurements and finite element simulation

The use of cold drawing processes for tubes is a flexible and well-established technology to reduce tube dimensions and improve their surface quality. However, wall thickness deviations over the circumference in the semi-finished goods – eccentricity – and residual stresses can be disadvantageous. Nevertheless, drawing with die tilting is clearly affecting the eccentricity as well as the residual stress development. In this paper the evolution of residual stresses over the wall thickness in cold drawn copper tubes was measured from the as-received state over the condition in the deformation zone with tilted dies and finally to the drawn tubes by means of neutron diffraction analysis at SALSA facility in Institut Laue-Langevin (ILL), Grenoble. A model was developed and the behavior of the residual stresses was simulated using the finite element method (FEM). The information about the evolution was necessary for the model and its verification. With this model – which is taking into account the influence of eccentricity on the residual stress development – the cost intensive neutron diffraction measurements can be reduced strongly. The verified model was used to calculate the residual stresses for standard drawn tubes and compared to tilted ones.

3D-Printable Materials for Microbial Liquid Culture

Abstract Additive manufacturing is providing the opportunity to easily fabricate complex structures for biological applications, such as growing microbial cultures. To best determine 3D-printable materials suitable for liquid microbial growth, culture tubes were printed that mimic the shape and dimensions of a standard commercial tube. Ten different printed materials were assessed in conjunction with multiple 3D printing platforms, and their performance to standard commercial polystyrene culture tubes was compared. In each test, a K-12 strain of the common laboratory bacterium Escherichia coli was monitored for growth over 24 h under normal conditions of temperature and agitation. Growth inhibition was observed for some printed materials, and mass spectrometry was used to identify two leached chemicals that inhibited bacterial growth. Based on this assessment, three of the materials are recommended for consideration in prototyping 3D-printed culture environments.

High-throughput Acid-Base Tandem Organocatalysis over Hollow Tube-Shaped Porous Polymers and Carbons

A FeCl3 mediated polymerization of 4-tritylaniline with dimethoxymethane (DMM) at 80 oC resulted the formation of hollow tube shaped porous polymers, which can be transformed into microflowers and larger hollow tubes (bamboo shaped) by increasing the amount of DMM during the synthesis. All polymers are converted to Microporus hollow carbon tubes (CT), carbon flowers (CF), extra-large carbon hollow tubes by simply pyrolyzing it at 600–700 oC under N2 atm. Among them only CTs having smaller dimension of hollow tubes, exhibits better CO2 uptake (120 cm3 g−1, 273 K) at 1 atm, higher than other microporous organic tubes. A one pot acid-base tandem organocatalysis has been carried out over these N-doped CT, CF and amine functionalized polymers after post grafting with –SO3H groups for the synthesis of 3-benzylidine malononitrile.

Characterization of Flow-resistant Tubes Used for Semi-occluded Vocal Tract Voice Training and Therapy

This study aimed to characterize the pressure-flow relationship of tubes used for semi-occluded vocal tract voice training/therapy, as well as to answer these major questions: (1) What is the relative importance of tube length to tube diameter? (2) What is the range of oral pressures achieved with tubes at phonation flow rates? (3) Does mouth configuration behind the tubes matter? Plastic tubes of various diameters and lengths were mounted in line with an upstream pipe, and the pressure drop across each tube was measured at stepwise increments in flow rate. Basic flow theory and modified flow theory equations were used to describe the pressure-flow relationship of the tubes based on diameter and length. Additionally, the upstream pipe diameter was varied to explore how mouth shape affects tube resistance. The modified equation provided an excellent prediction of the pressure-flow relationship across all tube sizes (6% error compared with the experimental data). Variation in upstream pipe diameter yielded up to 10% deviation in pressure for tube sizes typically used in voice training/therapy. Using the presented equations, we can characterize resistance for any tube based on diameter, length, and flow rate. With regard to the original questions, we found that (1) For commonly used tubes, diameter is the critical variable for governing flow resistance; (2) For phonation flow rates, a range of tube dimensions produced pressures between 0 and 7.0 kPa; and (3) The mouth pressure behind the lips will vary slightly with different mouth shapes, but this effect can be considered relatively insignificant.