Tube Length Research Articles

Research on unsteady characteristics of valveless piezoelectric micropump with planar conical tube

The model of valveless piezoelectric micropump with planar conical tube is established in this paper, and dynamic mesh technology is used to simulate the unsteady characteristics of the micropump at different pressure amplitudes and driving frequencies for different diffusion angles. The elements affecting the output performance of the micropump are analyzed. The research indicates that the longer the conical tube, the smaller the flux that flows into the cavity of the micropump during inhalation. While the longer the conical tube, the greater the flux that flows out of the cavity of the micropump during expulsion. The net output flux of the valveless piezoelectric micropump increases with the length of the conical tube. The rectification efficiencies of micropump with tube length of 1mm, 3mm, and 5mm are 8.77%, 14.58%, and 18%, respectively.

Design-encoded dual shape-morphing and shape-memory in 4D printed polymer parts toward cellularized vascular grafts.

Current additive manufacturing technologies wherein as-printed simple two-dimensional (2D) structures morph into complex tissue mimetic three-dimensional (3D) shapes are limited to multi-material hydrogel systems, which necessitates multiple fabrication steps and specific materials. This work utilizes a single shape memory thermoplastic polymer (SMP), PLMC (polylactide-co-trimethylene carbonate), to achieve programmable shape deformation through anisotropic design and infill angles encoded during 3D printing. The shape changes were first computationally predicted through finite element analysis (FEA) simulations and then experimentally validated through quantitative correlation. Rectangular 2D sheets could self-roll into complete hollow tubes of specific diameters (ranging from ≈6 mm to ≈10 mm) and lengths (as long as 40 mm), as quantitatively predicted from FEA simulations within one minute at relatively lower temperatures (≈80 °C). Furthermore, shape memory properties were demonstrated post-shape change to exhibit dual shape morphing at temperatures close to physiological levels. The tubes (retained as the permanent shape) were deformed into flat sheets (temporary shape), seeded with endothelial cells (at T < Tg), and thereafter triggered at ≈37 °C back into tubes (permanent shape), utilizing the shape memory properties to yield bioresorbable tubes with cellularized lumens for potential use as vascular grafts with improved long-term patency. Additionally, out-of-plane bending and twisting deformation were demonstrated in complex structures by careful control of infill angles that can unprecedently expand the scope of cellularized biomimetic 3D shapes. This work demonstrates the potential of the combination of shape morphing and SMP behaviors at physiological temperatures to yield next-generation smart implants with precise control over dimensions for tissue repair and regeneration.

A PARAMETRIC AND COMPARATIVE STUDY ON BARE-TUBE BANKS AND NEW CAM-SHAPED TUBE BANKS FOR WASTE HEAT RECOVERY APPLICATIONS

The present study numerically examines the effects of tube diameter (12 to 35 mm), arrangement, pitch-to-diameter ratio (1.25 to 2.5), length (300 to 1500 mm), and passage number (1-4 passes) on the thermofluidic characteristics of cross-flow tube bundles. Especially, five new cam-shaped tubes are proposed in comparison with the conventional round tube. The air temperatures at the cold and hot side inlets are kept constant at 25&amp;deg;C and 600&amp;deg;C, respectively. The numerical method is verified by the existing experimental results. The findings show that a cam-shaped tube with an equal diameter (Cam_1818) is a promising tube for tube bundles, which apply in waste heat recovery. Indeed, it can offer the same minimum gap as that of the round tube; however, it improves the total thermal resistance up to about 28&amp;#37; and enhances the heat-transfer rate up to an average of 42.3&amp;#37; compared to that of the round tubes at the same pumping power.

Floral visitors of sesame (Sesamum indicum L.): Elucidating their nectar-robbing behaviour and impacts on the plant reproduction.

Nectar robbing is common in angiosperms, especially in long tubular flowers or flowers with spurs that keep nectar out of reach of visitors. However, the robbing behaviour of bees is less understood. Here, we studied the sesame visitors, their robbing behaviour, and the impacts of robbing on plant reproductive fitness. Diverse insect species (primarily members of Hymenoptera) visited sesame flowers. The most effective pollinators were Amegilla zonata, Apis cerana, Apis dorsata, Apis florea, Ceratina binghami, Halictus acrocephalus and Xylocopa amethystina. Almost all visitors with variable percentages revealed the nectar-robbing phenomenon. Robbing activity depended on a complex of multiple attributes, including the visitor's body size, the corolla tube length, the availability and accessibility of nectar, and the resource-collecting task allocation of bees. Robbing activity varied according to flower-visiting species, flowering period and daytime. Robbing was comparatively higher in the late flowering period at 10.00-14.00 h. In the case of robbing visits, flower handling time was lower, and the visitation rate remained higher than non-robbing visits. Robbing visits did not significantly affect fruit and seed sets of sesame. Therefore, we can interpret the nectar-robbing interactions on sesame as commensal, with pollinators benefitting without altering the plant's reproductive fitness.

Pollination of Chamaepentas nobilis (Rubiaceae) by long‐proboscid hawkmoths in south‐central Africa: Trait mismatching and floral scent chemistry

AbstractThe evolution of extremely long (&gt;10 cm) floral tubes in angiosperms is closely linked with adaptation for pollination by long‐proboscid hawkmoths. In most cases, pollen is placed on the head or body of these moths, selecting for floral tubes that match or slightly exceed their proboscis length as this ensures contact with reproductive parts of the flower. However, in the case of Chamaepentas nobilis (Rubiaceae), anthers are inserted inside the c. 12‐cm floral tubes and coat the proboscis of visiting hawkmoths with sticky pollen, meaning that insects with proboscides longer than the floral tube can be effective pollinators, despite trait mismatching. Direct observations and camera trapping on granite outcrops in central Zambia showed that C. nobilis was visited both by Agrius convolvuli (proboscis length c. 13 cm) and Xanthopan morganii (proboscis length c. 17 cm), which are the only moth species in Africa that can access the small amounts of dilute nectar at the base of the floral tube. Pollen on the proboscides of captured hawkmoths was confirmed to originate from C. nobilis. Key floral advertising traits of C. nobilis include early evening anthesis, the highly reflective white limbus, and the evening production of scent dominated by oxygenated aromatic and terpenoid compounds known to elicit antennal responses of A. convolvuli. This study shows that that A. convolvuli and X. morganii share floral resources and jointly pollinate C. nobilis, despite their proboscides differing in length and being mismatched with the corolla tube length.

Development of Heat Exchanger for Syngas Purification in a Smart Mini-Grid Gasification Power Plant

The shell and tube heat exchanger was designed using a stainless pipe with a diameter of 203.2 mm (8 inches) and 3 mm thick. The design calculation results indicates that heat transfer rate was about and a tube length of 0.7 m was used and the number of tubes Nt is 17, this is required to cool the syngas from 350℃ to 80°C theoretically. Results obtained from CFD ANSYS software 2022 version showed that the verification of the model was achieved by comparing the theoretical temperatures of the syngas with the temperatures predicted from the simulation.

Magnetic Field Impact on Heat Transfer and Nano-Ferrofluid Flow in a Pipe

The research examines velocity, Nusselt number, Y plus, magnetism effectiveness, and flow of Fe3O4-distilled water in a magnetic field tube in order to investigate heat transfer and flow. Magnetic fields modify flow patterns by generating vortexes and changing thermal boundary layers. The surface of a model with a 210 mm tube length and a 25.4 mm inner diameter exhibits equal magnet shed spots. The entry of the nanomaterial at a temperature of 300 K is shown by the three different entrance velocities of 0.05, 0.1, and 0.5 m/s that were recorded at the entry region. These limitations were used. Three instances of the first magnets were taken when the middle magnet was switched on, followed by the first and third, and finally all three of them. In the exit region, an exit pressure of 0 pa was given to the surfaces of heat at a constant temperature of 350 K. Three magnetic flux forces one, two, and three Tesla were measured. The temperature value at the three magnets is 349 K, which is the biggest temperature value compared to the other examples, demonstrating that the temperature value rises with the number of magnetization stages.

Capillary Tube Length and Heat Transfer Dynamics in Air Conditioners: A Comparative Analysis of R-12 and Its Alternatives

Capillary Tube Length and Heat Transfer Dynamics in Air Conditioners: A Comparative Analysis of R-12 and Its Alternatives

Performance Evaluation of Centrifugal Pump-As-Turbine For Micro Hydro Applications

The Philippines is entirely dependent on imported hydropower (HP) system parts, specifically the turbine and generator. The use of a centrifugal pump as a turbine is a good option for the HP system due to its low cost and wide availability in the market. The performance of the centrifugal pump-as-turbine was evaluated under the following conditions: (1) different head setting, (2) different configurations of the draft tube, and (3) a match with an AC generator. A 75x75mm end suction, non-self-priming centrifugal pump was used in this study. The head settings used were 0.28 kg/cm2 to 0.84 kg/cm2 (pressure gauge reading). A prony brake dynamometer was fabricated to measure the torque at the shaft of the pump-as-turbine. The configurations of the draft tube used include: (a) conical angles - 0°, 4°, and 6°, and (b) draft tube lengths – 0.4572 m, 0.9144 m, and 1.3716 m. A 900W AC generator was matched with the pump–as–turbine and tested at different pressure and load settings. Results showed that the centrifugal pump could operate in turbine mode without any mechanical modifications. The highest mechanical efficiency obtained was 83.60% and was attained at a pressure setting of 0.70 kg/cm2. The highest shaft power of 1.02 kW that was attained at 0.84 kg/cm2 pressure setting. Based on the results, in terms of shaft power, the best draft tube configuration has a conical angle of 4° and a length of 1.3716 m. Meanwhile, in terms of efficiency, the best draft tube configuration is 4° conical angle and 0.4572 m length. The generator speed of 4000 rpm was obtained at a pressure setting of 0.84 kg/cm2. On the other hand, a generator speed of 3800 rpm was obtained at a pressure setting of 0.63 kg/cm2. It could be observed that the maximum power (515 W) obtained during the actual run was way below the expected output (847 W). The system efficiencies as well as the electrical power output could improve if the belt slippage is reduced. It is recommended to conduct more testing to be able to determine the full potential of the pump-as-turbine.

The use of variable coil pitch of helical tube on the hydro-thermal performance improvement

The use of helical tubes in heat transfer appliances is desirable due to their better heat transfer characteristics, but the higher pressure drop decreases the overall performance. The variation of pitch design of a helical tube is proposed to alleviate this situation so that the pitch number does not remain constant in the total tube length. A total of six variable pitch numbers with three different diameters are proposed and investigated on the thermal and fluid characteristics. To better understand the helical tube efficiency, PEC (performance evaluation criteria) is selected as a performance indicator in the present work and simulations are performed in a laminar regime (100 ≤ Re≤ 1600) at a constant heat flux boundary condition using computational fluid dynamics. The numerical results show that variable radial pitch has higher effects on the overall performance than variable axial pitch, and it can intensify the helical tube performance by up to 10%. The results also indicate that increasing the tube diameter leads to heat transfer and friction factor increment while increasing the Reynolds number deteriorates the overall performance.

Analysis of the Effectiveness of a Freight Transport Vehicle at High Speed in a Vacuum Tube (Hyperloop Transport System)

This paper shows the development of a numerical analysis model, which enables the calculation of the cargo transport capacity of a vehicle that circulates through a vacuum tube at high speed, whose effectiveness in transport is analyzed. The simulated transportation system is based on vehicles moving in vacuum tubes at high speed, a concept commonly known as Hyperloop, but assuming the vehicles for cargo containers. For the specific vehicle proposed, which does not include a compressor and levitates on magnets, the system formed by the vehicle and the vacuum tube has been conceptually developed, establishing the corresponding mathematical relationships that define its behavior. To properly model the performance of this transport system, it has been necessary to establish the relationships between the design variables and the associated constraints, such as the Kantrowitz limit, aerodynamics, transport, energy consumption, etc. Once the model was built and validated, it was used to analyze the effects of the variation of the number of containers, the operating speed and the tube length, considering the total and specific consumption of energy. After finding the most efficient configuration regarding energy consumption and transport effectiveness, the complete system was calculated. The results obtained constitute a first approximation for the predesign of this transport system and the built model allows different alternatives to be compared according to the design variables.

PiC/MC-simulation of a low-pressure discharge in helium initiated by a relativistic electron beam in a coaxial chamber with a magnetic cusp

A gas discharge is simulated and numerically studied. The discharge is excited by a tubular relativistic electron beam in gaseous helium in a coaxial gas-discharge chamber. A magnetic field in the form of a cusp was imposed on the chamber. The code based on the PiC/MC-method was used. Electron beam dynamics, time evolution of phase portraits of particles, physical parameters, and spatial-time characteristics of plasma were calculated. It is shown that a dense plasma appears in the cavity under the action of an electron beam in the form of a thin-walled tube of a large length; its concentration can be nHe+≈2×1010 cm−3. At the same time, it turned out that plasma is considerably non-uniform in length; its denser part corresponds to the parts where beams stop. Time dependence of the charge compensation of electrons on the helium atom concentration in the chamber was calculated. The dependence turned out to be decreasing since the rate of the discharge development is increasing with the growth of the helium pressure in the cavity.

Thermal performance enhancement in the receiver part of solar parabolic trough collectors

In this study, CFD analysis for thermal performance of absorber tube with inner helical axial fins which is used in solar PTC collector is considered and compared. Three-dimensional numerical model simulations were performed using flow and heat transfer interfaces in COMSOL Multiphysics software. Water is used as heat transfer fluid and copper was chosen as receiver tube material. Sun's radiation is considered as constant at around (Io=1000 W/m2) and concentration ratio is C=60. Inlet velocity of heat transfer fluid is changed from 0.2ms to 0.2 4 ms in order to define its magnitude with the length of absorber tube. Electrical analog method is utilized for mathematical modeling to evaluate heat losses through the absorber tube. Variations of surface and fluid temperature are determined to investigate the receiver which shows better performance in the given boundary conditions. In the discussion section of the article, temperature variation of the receiver tube and HTF during this process is presented.

Anti-Angiogenic Effect of Clerodendreme inerme Leaves Extract

Clerodendrum inerme, a medicinal plant, exhibits diverse pharmacological properties. Various species within the Clerodendrum genus have been traditionally utilized in indigenous medical systems and folk remedies. This study intended to scrutinize the anti-angiogenic possibility of CI through in-ovo, in-vitro, and in-vivo approaches. The screening methods employed include the chick chorioallantoic membrane test (in-ovo), sponge bud technique (in-vivo), as well as in-vitro assays for cell migration, cell proliferation, along with morphogenesis. Statistical analyses involved Dunnett’s test for mean comparisons, utilizing one-way ANOVA. In the chick chorioallantoic membrane assay, both angiogenic score and branching points were evaluated. Notably, CI exhibited noteworthy antiangiogenic effects. In the sponge implantation technique, CI at specified dosages resulted in a substantial reduction in sponge weights, the formation of new vessels, and hemoglobin levels. The antiangiogenic effects were particularly pronounced with increasing doses. Furthermore, on endothelial cells, C. inerme demonstrated a dose-dependent decrease in migration, proliferation, and tube length, indicating potent antiangiogenic properties. In summary, this research underscores the considerable antiangiogenic potential of CI by various assays.

Influence of Anodizing Parameters on the Morphological Characteristics of TNTAs

TiO2 nanotubes arrays (TNTAs) were synthesized using the anodization method in ethylene glycol (EG)-based electrolyte with different percentages of ammonium fluoride (0.3, 0.4, and 0.5 wt.%) and water content (2.5, 5, and 7.5% vol%). All the samples were ultrasonically cleaned in acetone, ethanol, and deionized water, then dried in air and kept in an etching solution for a while before anodization. The two-step anodization was carried out, followed by thermal treatment at 450°C for the crystallization. The nanotube samples were characterized using FE-SEM analysis. The FE-SEM results showed that the largest tube diameter was 87.74±1.89 nm of the TNTAs prepared in the EG electrolyte with a composition of 7.5% water content and 0.5% ammonium fluoride. The longest tube length analyzed was around 5.3 µm of the TNTAs prepared in the ethylene glycol electrolyte with the composition of 2.5% water content and 0.4% ammonium fluoride percentage, exhibiting a highly ordered, compact honeycomb structure and thick single-walled structure.

A novel genotype-phenotype between persistent-cloaca-related VACTERL and mutations of 8p23 and 12q23.1.

The mechanism underlying anorectal malformations (ARMs)-related VACTERL (vertebral defects, anal atresia, cardiac defects, tracheo-esophageal fistula, and renal and limb abnormalities) remains unclear. Copy number variation (CNV) contributed to VACTERL pathogenicity. Here, we report a novel CNV in 8p23 and 12q23.1 identified in a case of ARMs-related VACTERL association. This 12-year-old girl presented a cloaca (urethra, vagina, and rectum opening together and sharing a single tube length), an isolated kidney, and a perpetuation of the left superior vena cava at birth. Her intelligence, growth, and development were slightly lower than those of normal children of the same age. Array comparative genomic hybridization revealed a 9.6-Mb deletion in 8p23.1-23.3 and a 0.52-Mb duplication in 12q23.1 in her genome. Furthermore, we reviewed the cases involving CNVs in patients with VACTERL, 8p23 deletion, and 12q23.1 duplication, and our case was the first displaying ARMs-related VACTERL association with CNV in 8p23 and 12q23.1. These findings enriched our understanding between VACTERL association and the mutations of 8p23 deletion and 12q23.1 duplication. IMPACT: This is a novel case of a Chinese girl with anorectal malformations (ARMs)-related VACTERL with an 8p23.1-23.3 deletion and 12q23.1 duplication. Cloaca malformation is presented with novel copy number variation in 8p23.1-23.3 deletion and 12q23.1 duplication.

Numerical analysis of thermo hydro-dynamics behavior of solar flat plate collector with square and V-cut twisted tape inserts

Numerical analysis has been conducted for a solar collector with two circular pipes having semi-circular contact with absorber plate. The tubes are analyzed with and without the inclusion of twisted tape inserts of twist ratio Y = 3 and Y = 4. The comparison between the heat transfer and pressure drop characteristics of a plain tube to that fitted with the twisted tape inserts is done and validated against experimental results with good agreement. Additionally, helical twisted tape is modeled with square- and V-cut to analyze its influence on flow and heat transfer phenomenon. V-cut twisted tape inserts act as turbulence promoters, increasing fluid flow and inducing vortex-like motion. As a result, boundary layer around the absorber plate is disrupted with decrease in stagnation temperature, resulting in better heat transfer and more effective absorption and conversion of solar energy. The Nusselt number, friction factor, and heat transfer coefficient variation with the Reynolds number have been studied for the given heat fluxes. It is found that the Nusselt number of the fluid flowing in the plain tube is increased by 76.44% when the tube is fitted with twisted tape inserts. The pressure drop in the tube is found to increase with the presence of the twisted tapes. The average temperature along the length of the circular tube and absorber plate has also been reported.

Drivers of sunbird‐plant interactions on Mount Cameroon: Between neutrality and niche‐based processes

AbstractThe drivers behind plant‐pollinator interactions still need to be fully understood. Previous research has suggested that observed interactions result from either neutral interaction between species based on their abundance or from niche‐based processes, which are reflected in the adaptations of both plants and pollinators. Furthermore, the importance of both scenarios can differ depending on seasonal dynamics translated into differences in resource availability. Extensive research has been conducted on New‐World hummingbirds (Trochilidae), whereas much less is known about Old World nectar‐feeding sunbirds (Nectariniidae). Our study aimed to explore whether sunbird‐plant interactions are explained by neutral and/or niche‐based processes. Thus, we tested the effects of abundance, morphology, and nectar sugar content on the observed interactions and the link between sunbirds and plant traits. Moreover, we explored the effects of robbing on these mechanisms. Finally, we investigated the partitioning of bird pollination niches, based on floral traits. We used a dataset of sunbird‐plant interactions collected at Mount Cameroon during two seasons (dry and wet seasons). Our study shows that sunbird‐plant interactions are influenced by both neutral and niche‐based processes. Neutral processes and nectar reward were the main mechanisms underlaying the observed interactions in the dry season. However, as more ornithophilous plants bloom during the rainy season, morphological trait‐matching becomes more important. We found a correlation between bill length and floral tube dimensions and observed niche overlap among the sunbird species. Considering this and other research, we suggest that plant‐pollinator interactions are influenced by a combination of both neutral and niche‐based processes.

Towards an optimal frequency and time response of singe-tube pressure measurement systems under continuum-flow conditions

The pressure transmission tube, as part of a pressure measurement system, generally has a considerable influence on its dynamic characteristics. The paper deals with the mathematical modelling of the dynamic behaviour of pressure transmission tubes with the aim of providing guidelines for the optimal design of such systems in the frequency and time domains. The mathematical models used are based on linear wave theory and continuum flow mechanics with no-slip and isothermal boundary conditions. The frequency responses were evaluated in terms of frequency bandwidth and the transient step responses in terms of settling and rise times. Following a systematic analysis of these characteristic parameters, we derived an analytically formulated optimisation objective function defining the transition between the low-wavenumber and high-wavenumber pressure waves in the pressure transmission tubes. The demanded dynamic behaviour in the frequency and time domains can be achieved through an appropriate ratio between the actual tube radius and the so-called transition tube radius, which was derived as a function of the tube length, end volume and fluid properties.

Hydrodynamic performance of an elastic capsule oscillating water column type WEC: An experimental study

Wave energy represents a promising and sustainable source of energy with substantial potential. To promote the utilization of wave energy resources as well as develop new wave energy converters (WECs) with application prospects, an innovative elastic capsule oscillating water column (EC-OWC) WEC is proposed, and an initial experimental investigation is conducted on the device. Besides, the expansion characteristics of the elastic capsule and the motion characteristics of the free bulge wave are investigated through bulge wave tests. Moreover, the hydrodynamic performances of the device on the condition that coupled with traveling regular waves are investigated through wave tests, as well as the damping characteristics of the impulse turbine model and the ring-opening as power take-off (PTO) systems in the EC-OWC. It indicates that the variation in the speed of the free bulge wave is consistent with the one-dimensional longitudinal wave theory, that the ring-opening model with an opening ratio of 0.76 percent has comparable operating characteristics to the impulse turbine, and that the impulse turbine model has outstanding operating characteristics in the EC-OWC system. The maximum primary hydrodynamic efficiency of the system is approximately 0.475. When the relative water depth is in the interval of approximately 0.07-0.09, the efficiency can reach 0.4. Furthermore, the efficiency increases and subsequently decreases with the variation of the relative hydraulic head, and the efficiency reaches the maximum value when the relative tube length is around 1.6. The results indicate that the one-dimensional longitudinal wave theory can provide support for the design of the elastic capsule. When the capsule length is close to half a wavelength and the internal and external oscillation periods are matched, the system reaches a near-resonant state, and the level of efficiency is optimized. The bulge wave contained within the EC-OWC is a half-wavelength standing wave.