Tube Assembly Research Articles

Development of a 3-D visible limiter imaging system for the HSX stellarator.

A visible camera diagnostic has been developed to study the Helically Symmetric eXperiment (HSX) limiter plasma interaction. A straight line view from the camera location to the limiter was not possible due to the complex 3D stellarator geometry of HSX, so it was necessary to insert a mirror/lens system into the plasma edge. A custom support structure for this optical system tailored to the HSX geometry was designed and installed. This system holds the optics tube assembly at the required angle for the desired view to both minimize system stress and facilitate robust and repeatable camera positioning. The camera system has been absolutely calibrated and using Hα and C-III filters can provide hydrogen and carbon photon fluxes, which through an S/XB coefficient can be converted into particle fluxes. The resulting measurements have been used to obtain the characteristic penetration length of hydrogen and C-III species. The hydrogen λiz value shows reasonable agreement with the value predicted by a 1D penetration length calculation.

An evaluation for tube assembly performance based on virtual fixtures

There are a lot of complex tubing in aviation, aerospace, automobile, and other industrial machinery and equipment. The reliable assembly of these tubing directly affects the quality of the product...

On the influence of pseudoelastic material behaviour in planar shape-memory tubular continuum structures

For planar tubular continuum structures based on precurved shape memory alloy tubes a beam model with respect to the pseudoelastic material behaviour of NiTi is derived. Thereunto a constitutive material law respecting tension-compression asymmetry as well as hysteresis is used. The beam model is then employed to calculate equilibrium curvatures of concentric tube assemblies without clearance between the tubes. In a second step, the influence of clearance is approximated to account for non-concentric tube assemblies. These elastokinematic results are integrated into a purely kinematic model to describe the cannula path under the presence of material hysteresis and clearance. Finally a photogrammetric measurement system is used to track the path of an exemplary two-tube continuum structure to examine the accuracy of the proposed model. It is shown that material hysteresis leads to a hysteresis phenomena in the path of the tubular continuum structure.

Standardization of the collection of exhaled breath condensate and exhaled breath aerosol using a feedback regulated sampling device

Exhaled breath condensate (EBC) and associated exhaled breath aerosols (EBA) are valuable non-invasive biological media used for the quantification of biomarkers. EBC contains exhaled water vapor, soluble gas-phase (polar) organic compounds, ionic species, plus other species including semi- and non-volatile organic compounds, proteins, cell fragments, DNA, dissolved inorganic compounds, ions, and microbiota (bacteria and viruses) dissolved in the co-collected EBA. EBC is collected from subjects who breathe ‘normally’ through a chilled tube assembly for approximately 10 min and is then harvested into small vials for analysis. Aerosol filters without the chilled tube assembly are also used to separately collect EBA. Unlike typical gas-phase breath samples used for environmental and clinical applications, the constituents of EBC and EBA are not easily characterized by total volume or carbon dioxide (CO2) concentration, because the gas-phase is vented. Furthermore, EBC and associated EBA are greatly affected by breathing protocol, more specifically, depth of inhalation and expelled breath velocity. We have tested a new instrument developed by Loccioni Gruppa Humancare (Ancona, Italy) for implementation of EBC collection from human subjects to assess EBC collection parameters. The instrument is the first EBC collection device that provides instantaneous visual feedback to the subjects to control breathing patterns. In this report we describe the operation of the instrument, and present an overview of performance and analytical applications.

Variceal Tamponade: Teaching New Dogs Old Tricks! A Performance Improvement Project

Introduction: Acute esophageal variceal hemorrhage is a dreaded complication of chronic liver disease that nearly every endoscopist will encounter during their career. In the event of failed endoscopic treatment, it is vital for one to be knowledgeable on the proper use and placement of balloon tamponade as a bridge to repeat endoscopy or transjugular intrahepatic portosystemic shunt procedure. There are many obstacles that can make the use of balloon tamponade more challenging, such as maintaining the knowledge and skill for placement given rarity of use, locating all necessary required components for proper function (these are not provided from the tube manufacturer), and educating the team and ancillary staff on tube care post-placement. Our aim in this project was to standardize the balloon tamponade process by re-educating our gastroenterology providers on tube placement and developing a balloon tamponade “kit” containing all required accessories and instructions to improve the ease and safety when this emergency intervention is required. Methods: We devised a five-question pre and post-intervention survey to test our seven staff gastroenterologists and six fellows on their knowledge of locating all components of the balloon tamponade tube, details of tube placement, and post-placement tube instructions. The intervention included introduction of our new tube kit along with a one-on-one, 20-25 minute demonstration of tube assembly, placement, troubleshooting, and post tube care instructions. We then measured improvement between pre and posttest surveys using a paired t-test. Results: There was a statistically significant improvement in confidence with each tested component of our survey, as well as for the entire group of questions post-education intervention (P<0.001), see Table 1.Table: Table. Pre/Post Test SummaryConclusion: Our balloon tamponade project was a success in standardizing the use of this device. It was also effective in refreshing our providers on proper tube placement, use, and post-placement tube care. Moving forward, our institution will continue to utilize this balloon tamponade kit until newer options become standard of care. Sample size may have been a limitation in our study. In the future, we are planning to reproduce this project to include the internal medicine residents who are typically first line in acute variceal hemorrhage cases prior to gastroenterology consultation and are usually involved in tube placement.

Hydrodynamics around a shroud tube assembly of a fast breeder reactor

Control plug assembly of a liquid sodium cooled fast breeder reactor is partially submerged inside the liquid sodium coolant pool, free surface of which is blanketed with cover gas, mainly Argon to provide a non-reactive environment. It receives high velocity coolant flow from the fuel subassembly which travels through annular gap inside Control Safety Rod Driving Mechanism (CSRDM) assembly leading to swelling of free surface and gas entrainment inside the coolant pool. Entrained gas bubbles travel through different submerged components of the reactor and induces numerous complications including reactor power fluctuation, cavitation in inlet pumps and heat transfer inhibition in heat exchangers. Study of hydrodynamics around the shroud tube is crucial to examine cover gas entrainment inside the pool. The present study reports an experimental study on a 1:9 scale down model of CSRDM shroud tube assembly based on Froude number similarity. Eccentricity of the control rod inside the shroud tube is also an important parameter as temperature gradient along the CSRDM assembly leads to longitudinal thermal stress causing displacement of control rod from its center position in the shroud tube. Flow behavior around shroud tube, hump formation at the axial exit of shroud tube, air entrainment inside coolant pool have been reported for various parameters viz. inlet flow rate (qi), free surface height (hf) and eccentricity of central rod (e). Dye visualization, Schlieren visualization, Bulk visualization have been carried out and digital image processing techniques have been adopted for quantification of hump parameters and entrained air fraction inside the coolant pool.The axial flow from the exit of the shroud tube impinges on the free surface like a wall jet. At low Froude number, the impinging jet flow travels radially outward on the interface like a wall jet boundary layer. The shear of the free surface flow drags the jet like flow from the pores upward leading to mixing between the vortices inside the shear layer and the free vortices from the pores of the shroud tube. At high Froude number, the impinging jet like flow penetrates through the interface leading to hump formation. The downward motion of the hump reduces the radial free surface flow and blankets the radial flow from the pores of the shroud tube. The eccentricity of the central rod leads to asymmetric axial flow from the shroud tube and thus the resulting hump becomes asymmetric due to impingement of asymmetric jet. Therefore, the impingement angle of the downward hump motion becomes different at both sides of the shroud tube with asymmetric flow field and bubble formation process inside the liquid pool. However, the synchronization between the hump unsteadiness and the surface wave motion leads to mixing of air bubbles inside the liquid pool. Average entrained air fraction increases with increase in inlet flow rate and decreases with increase in free surface height.

Src- and Fyn-dependent apical membrane trafficking events control endothelial lumen formation during vascular tube morphogenesis.

Here we examine the question of how endothelial cells (ECs) develop their apical membrane surface domain during lumen and tube formation. We demonstrate marked apical membrane targeting of activated Src kinases to this apical domain during early and late stages of this process. Immunostaining for phosphotyrosine or phospho-Src reveals apical membrane staining in intracellular vacuoles initially. This is then followed by vacuole to vacuole fusion events to generate an apical luminal membrane, which is similarly decorated with activated phospho-Src kinases. Functional blockade of Src kinases completely blocks EC lumen and tube formation, whether this occurs during vasculogenic tube assembly or angiogenic sprouting events. Multiple Src kinases participate in this apical membrane formation process and siRNA suppression of Src, Fyn and Yes, but not Lyn, blocks EC lumen formation. We also demonstrate strong apical targeting of Src-GFP and Fyn-GFP fusion proteins and increasing their expression enhances lumen formation. Finally, we show that Src- and Fyn-associated vacuoles track and fuse along a subapically polarized microtubule cytoskeleton, which is highly acetylated. These vacuoles generate the apical luminal membrane in a stereotypically polarized, perinuclear position. Overall, our study identifies a critical role for Src kinases in creating and decorating the EC apical membrane surface during early and late stages of lumen and tube formation, a central event in the molecular control of vascular morphogenesis.

Solid‐State NMR H–N–(C)–H and H–N–C–C 3D/4D Correlation Experiments for Resonance Assignment of Large Proteins

Solid-state NMR spectroscopy can provide insight into protein structure and dynamics at the atomic level without inherent protein size limitations. However, a major hurdle to studying large proteins by solid-state NMR spectroscopy is related to spectral complexity and resonance overlap, which increase with molecular weight and severely hamper the assignment process. Here the use of two sets of experiments is shown to expand the tool kit of 1 H-detected assignment approaches, which correlate a given amide pair either to the two adjacent CO-CA pairs (4D hCOCANH/hCOCAcoNH), or to the amide 1 H of the neighboring residue (3D HcocaNH/HcacoNH, which can be extended to 5D). The experiments are based on efficient coherence transfers between backbone atoms using INEPT transfers between carbons and cross-polarization for heteronuclear transfers. The utility of these experiments is exemplified with application to assemblies of deuterated, fully amide-protonated proteins from approximately 20 to 60 kDa monomer, at magic-angle spinning (MAS) frequencies from approximately 40 to 55 kHz. These experiments will also be applicable to protonated proteins at higher MAS frequencies. The resonance assignment of a domain within the 50.4 kDa bacteriophage T5 tube protein pb6 is reported, and this is compared to NMR assignments of the isolated domain in solution. This comparison reveals contacts of this domain to the core of the polymeric tail tube assembly.

Performance simulation on unilateral ladder type helical baffle heat exchanger in half cylindrical space

A unilateral ladder type helical baffle heat exchanger (ULHBHX) which is a novel countercurrent U-tube heat exchanger was proposed and investigated for better characteristics of high heat transfer coefficient, low resistance, anti-vibration and anti-fouling with a spiral flow pattern than those of the conventional segment one. The numerical model of ULHBHX was established and simulated by CFD software with 38 heat transfer tubes and 2 rod and spacing tube assemblies in the lower half cylindrical space under the parameters of subcooling of a high pressure feedwater heater in power plants. Different views such as on baffle-parallel slices and polygonal slices were presented to show the flow patterns of the main helical flow, secondary vortex flow and the leakage flow. The influences of geometrical parameters of baffle pitch and projection length of the inclined section on heat transfer and pressure drop were discussed quantitatively. The results show that the shell-side heat transfer coefficient ho of the ULHBHXs is 13.2%–18.2%, with an average of 16.0%, higher than those of the corresponding segment schemes, and the comprehensive index hoΔpo−1/3 is 15.7%–46.4%, with an average of 28.3%, higher than those of the corresponding segment schemes with identical baffle pitches in the discussed range.

Numerical and experimental study on biased tube temperature problem in tangential firing boiler

In this study, a numerical and experimental investigation on the flow field in a 500-MW unit of a tangentially fired boiler has been performed to understand the effect of residual swirl on the temperature distribution and inconsistency of flow velocity in the crossover pass. The k–kL–ω turbulence model was used in this study to analyse the possible formation of transition flow in the tangential firing boiler. Furthermore, 1D and 3D hybrid modelling were used for the simulation of the convective heat transfer in the boiler tube assembly. The commercially available code ANSYS Fluent and COMSOL were used for the studies, respectively. The numerical results for the velocity profile and residual swirl in the boiler were validated using the experimental results from the cold air velocity test, in which the flow velocity was directly measured in the full-scale boiler. The computational results agreed well with the experimental findings. Furthermore, from a comparison of the simulation and experiment, it was found that the biased gas flow induces non-uniform tube temperatures at the crossover pass area of the tangential firing boiler. These results aid in the detailed study of the residual swirl effects on the temperature or flue gas at various locations of the boiler. This study indicates that a non-uniform tube temperature at the crossover pass is an inherent problem resulting from residual swirl in the tangential firing boiler. Therefore, the pulverised coal burner should be fine-tuned to avoid tube rupture due to local overheating.

Composite Absorber in Collision Simulations of a Bus

Abstract This paper details the numerical modeling of composite absorbers and an assessment of the influence of such deformation elements on a bus during frontal collision with a car. The absorber itself is designed as an assembly of thin-walled composite wound tubes oriented in the vehicle direction of travel. During the impact the tubes are crushed, causing energy absorption. Crash simulations were performed at various speeds using differing scenarios with the deformational member as well as without it. Comparative diagrams of force and velocity of the car and deformation of the bus structure were assessed

Cyclic analysis and optimization of design parameters for Beta-configuration Stirling engine using rhombic drive

Design and development of Beta configuration Stirling engine is a complex combination of thermodynamic analysis and mechanical design of components. The present work uses the second order cyclic analysis for the thermodynamic investigations and includes the effect of the overlapping volume displaced by piston and displacer within cylinder. It determines the ideal heat input, ideal power output and related losses separately. This provides estimate of net heat input, net brake power and cooling duty. The sensitivity analysis of various design and operating parameters is carried out to decide the order in which these should be modified and includes heater tube assembly parameters; annular regenerator assembly parameters; and cooler assembly parameters, using univariate method. The optimization considers the combined effect of the net power output and the efficiency instead of a single Optimization Parameter. The present work thus presents the cyclic analysis and optimization of design parameters of a Beta configuration Stirling Engine of 1.5kWe using rhombic drive. It was observed that the power output exceeds the requirement of 1.5kWe. Instead of carrying out the optimization process all over again, the operating parameter pmean is adjusted to 24bar to obtain the desired output of 1.5kWe.

In vitro assembly of the Rous Sarcoma Virus capsid protein into hexamer tubes at physiological temperature

During a proteolytically-driven maturation process, the orthoretroviral capsid protein (CA) assembles to form the convex shell that surrounds the viral genome. In some orthoretroviruses, including Rous Sarcoma Virus (RSV), CA carries a short and hydrophobic spacer peptide (SP) at its C-terminus early in the maturation process, which is progressively removed as maturation proceeds. In this work, we show that RSV CA assembles in vitro at near-physiological temperatures, forming hexamer tubes that effectively model the mature capsid surface. Tube assembly is strongly influenced by electrostatic effects, and is a nucleated process that remains thermodynamically favored at lower temperatures, but is effectively arrested by the large Gibbs energy barrier associated with nucleation. RSV CA tubes are multi-layered, being formed by nested and concentric tubes of capsid hexamers. However the spacer peptide acts as a layering determinant during tube assembly. If only a minor fraction of CA-SP is present, multi-layered tube formation is blocked, and single-layered tubes predominate. This likely prevents formation of biologically aberrant multi-layered capsids in the virion. The generation of single-layered hexamer tubes facilitated 3D helical image reconstruction from cryo-electron microscopy data, revealing the basic tube architecture.

Thermomechanical Behavior of Coolant Channel Assembly in Heavy Water Reactor Under Severe Plant Condition

The objective of current study is to develop and verify computer models to accurately predict the behavior of reactor structural components under operating and off-normal conditions. Indian pressurized heavy water reactors (PHWRs) are tube type of reactors. The coolant channel assemblies, being one of the most important components, need detailed analysis under all operating conditions as well as during postulated conditions of accidents for its thermomechanical behavior. One of the postulated accident scenarios for heavy water moderated pressure tube type of reactors, i.e., PHWRs, is loss of coolant accident (LOCA) coincident with loss of emergency core cooling system (LOECCS). In this case, even though the reactor is tripped, the decay heat may not be removed adequately due to low- or no-flow condition and inventory depletion of primary side. Initially, this will result in high temperature of the fuel pins. Since the emergency core cooling system (ECCS) is presumed to be not available, the cooling of the fuel pins and the coolant channel assembly depends on the moderator cooling system, which is assumed to be available. Moderator cooling system is a separate system in PHWRs. In PHWRs, the fuel assembly is surrounded by pressure tube, an annulus insulating environment, and a concentric calandria tube. In this postulated accident scenario, a structural integrity evaluation has been carried out to assess the modes of deformation of pressure tube—calandria tube assembly in a tube type nuclear reactor. The loading of pressure and temperature causes the pressure tube to sag (by weight of fuel bundle) and/or balloon (by internal pressure) and come in contact with the outer cooler calandria tube. The resulting heat transfer could cool and thus control the deformation of the pressure tube thus introducing interdependency between thermal and mechanical contact behavior. The amount of heat thus expelled significantly depends on the thermal contact conductance (TCC) and the nature of contact between the two tubes. Deformation of pressure tube creates a heat removal path to the relatively cold moderator. This, in turn, limits the temperature of fuel for a sufficiently long period and ensures safety of the plant. The objective of this paper is to provide insights into this thermomechanical behavior by computational studies and to understand the role of underlying parameters (such as material constants, thermal contact conductance, and boundary conditions) that control the tube deformation and further damage progression. The deformation characteristics of the pressure tube have been modeled using finite-element-based program. Experimental data of pressure tube material, generated for this research work, were used in modeling and examining the role of nonlinear stress–strain laws in the finite-element analyses.

Development of an Adaptive Food Preservation System for food quality and energy efficiency enhancement

This paper proposes a system design of an Adaptive Food Preservation System (AFPS). It is motivated by the fact that constant storage condition in today's refrigerators has deficiency. Customized storage with fast freezing capability can better manage food quality and energy efficiency. Key components include AFPS packages and vortex tubes. Superior fast freezing capability is demonstrated by comparisons with benchmarks from refrigerator tests and regulatory standards, and experimentation with a simulated test setup at various settings of input. Theoretical and analytical models are proposed to predict package inlet and exit temperatures, freezing capacities, and freezing efficiencies. At 7 bar inlet pressure, the maximum available freezing efficiency, mean efficiencies with vacuum insulation and with ABS insulation of the AFPS Package and Vortex Tube Assembly are 6%, 4.66%, and 2.80%, respectively. AFPS technology consumes 0.18% in time and 45% in energy during fast freezing comparing with what a typical household freezer does.

Platelet-derived growth factor (PDGF) signaling directs cardiomyocyte movement toward the midline during heart tube assembly.

Communication between neighboring tissues plays a central role in guiding organ morphogenesis. During heart tube assembly, interactions with the adjacent endoderm control the medial movement of cardiomyocytes, a process referred to as cardiac fusion. However, the molecular underpinnings of this endodermal-myocardial relationship remain unclear. Here, we show an essential role for platelet-derived growth factor receptor alpha (Pdgfra) in directing cardiac fusion. Mutation of pdgfra disrupts heart tube assembly in both zebrafish and mouse. Timelapse analysis of individual cardiomyocyte trajectories reveals misdirected cells in zebrafish pdgfra mutants, suggesting that PDGF signaling steers cardiomyocytes toward the midline during cardiac fusion. Intriguingly, the ligand pdgfaa is expressed in the endoderm medial to the pdgfra-expressing myocardial precursors. Ectopic expression of pdgfaa interferes with cardiac fusion, consistent with an instructive role for PDGF signaling. Together, these data uncover a novel mechanism through which endodermal-myocardial communication can guide the cell movements that initiate cardiac morphogenesis.

Mitigation of Ground Vibration due to Collapse of a Large-Scale Cooling Tower with Novel Application of Materials as Cushions

Ground vibration induced by the collapse of large-scale cooling towers in nuclear power plants (NPPs) has recently been realized as a potential secondary disaster to adjacent nuclear-related facilities with demands for vibration mitigation. The previous concept to design cooling towers and nuclear-related facilities operating in a containment as isolated components in NPPs is inappropriate in a limited site which is the cases for inland NPPs in China. This paper presents a numerical study on the mitigation of ground vibration in a “cooling tower-soil-containment” system via a novel application of two materials acting as cushions underneath cooling towers, that is, foamed concrete and a “tube assembly.” Comprehensive “cooling tower-cushion-soil” models were built with reasonable cushion material models. Computational cases were performed to demonstrate the effect of vibration mitigation using seven earthquake waves. Results found that collapse-induced ground vibrations at a point with a distance of 300 m were reduced in average by 91%, 79%, and 92% in radial, tangential, and vertical directions when foamed concrete was used, and the vibrations at the same point were reduced by 53%, 32%, and 59% when the “tube assembly” was applied, respectively. Therefore, remarkable vibration mitigation was achieved in both cases to enhance the resilience of the “cooling tower-soil-containment” system against the secondary disaster.

Optimal Branching Structure of Fluidic Networks with Permeable Walls.

Biological and engineering studies of Hess-Murray's law are focused on assemblies of tubes with impermeable walls. Blood vessels and airways have permeable walls to allow the exchange of fluid and other dissolved substances with tissues. Should Hess-Murray's law hold for bifurcating systems in which the walls of the vessels are permeable to fluid? This paper investigates the fluid flow in a porous-walled T-shaped assembly of vessels. Fluid flow in this branching flow structure is studied numerically to predict the configuration that provides greater access to the flow. Our findings indicate, among other results, that an asymmetric flow (i.e., breaking the symmetry of the flow distribution) may occur in this symmetrical dichotomous system. To derive expressions for the optimum branching sizes, the hydraulic resistance of the branched system is computed. Here we show the T-shaped assembly of vessels is only conforming to Hess-Murray's law optimum as long as they have impervious walls. Findings also indicate that the optimum relationship between the sizes of parent and daughter tubes depends on the wall permeability of the assembled tubes. Our results agree with analytical results obtained from a variety of sources and provide new insights into the dynamics within the assembly of vessels.

Determining the Optimum Inner Diameter of Condenser Tubes Based on Thermodynamic Objective Functions and an Economic Analysis

The diameter and configuration of tubes are important design parameters of power condensers. If a proper tube diameter is applied during the design of a power unit, a high energy efficiency of the condenser itself can be achieved and the performance of the whole power generation unit can be improved. If a tube assembly is to be replaced, one should verify whether the chosen condenser tube diameter is correct. Using a diameter that is too large increases the heat transfer area, leading to over-dimensioning and higher costs of building the condenser. On the other hand, if the diameter is too small, water flows faster through the tubes, which results in larger flow resistance and larger pumping power of the cooling-water pump. Both simple and complex methods can be applied to determine the condenser tube diameter. The paper proposes a method of technical and economic optimisation taking into account the performance of a condenser, the low-pressure (LP) part of a turbine, and a cooling-water pump as well as the profit from electric power generation and costs of building the condenser and pumping cooling water. The results obtained by this method were compared with those provided by the following simpler methods: minimization of the entropy generation rate per unit length of a condenser tube (considering entropy generation due to heat transfer and resistance of cooling-water flow), minimization of the total entropy generation rate (considering entropy generation for the system comprising the LP part of the turbine, the condenser, and the cooling-water pump), and maximization of the power unit’s output. The proposed methods were used to verify diameters of tubes in power condensers in a200-MW and a 500-MW power units.

Comparison in partition efficiency of protein separation between four different tubing modifications in spiral high-speed countercurrent chromatography.

High-speed countercurrent chromatography with a spiral tube assembly can retain a satisfactory amount of stationary phase of polymer phase systems used for protein separation. In order to improve the partition efficiency a simple tool to modify the tubing shapes was fabricated, and the following four different tubing modifications were made: intermittently pressed at 10 mm width, flat, flat-wave, and flat-twist. Partition efficiencies of the separation column made from these modified tubing were examined in protein separation with an aqueous-aqueous polymer phase system at flow rates of 1-2 ml/min under 800 rpm. The results indicated that the column with all modified tubing improved the partition efficiency at a flow rate of 1 ml/min, but at a higher flow rate of 2 ml/min the columns made of flattened tubing showed lowered partition efficiency apparently due to the loss of the retained stationary phase. Among all the modified columns, the column with intermittently pressed tubing gave the best peak resolution. It may be concluded that the intermittently pressed and flat-twist improve the partition efficiency in a semi-preparative separation while other modified tubing of flat and flat-wave configurations may be used for analytical separations with a low flow rate.