Slender Tube Research Articles

Behavior of eccentrically loaded slender concrete-filled steel tubes with defect representing random local corrosion

This paper focuses on the eccentric compression behavior of slender concrete-filled steel tubes (CFSTs) subjected to random localized corrosion and the localized corrosion was represented by a local defect. The randomness of corrosion includes the random locations and the random geometric characteristics that involve irregular corrosion profiles and uneven surfaces. Corrosion on the steel tube was represented by a defect in the experiment. The influence of spatial characteristics of local corrosion was investigated by seven CFST beam-column specimens, each featuring the defect in different locations along both height and circumferential directions. It was indicated through test results that both dimensions and locations of the defect considerably affected the failure mode and ultimate strength of the CFSTs. A numerical analysis was performed to confirm that local corrosion with irregular shape and uneven surface on a CFST beam-column can be approximated by a constant-depth circumscribed rectangular defect. Subsequently, a parametric analysis was conducted to find out how the corrosion dimensions, locations, and other critical parameters such as steel ratio, slenderness ratio, and material strengths influence the eccentric compression behavior of CFST. It revealed that negligible effects from local corrosion were observed in cases where slight corrosion was located near the column end. Finally, a calculation method was introduced to predict the ultimate strength of randomly localized corroded CFST beam-columns, with high precision.

On reduction of noise emissions from thin-walled slender tubes by means of acoustic metamaterials

On reduction of noise emissions from thin-walled slender tubes by means of acoustic metamaterials

An integrated strategy for reducing anastomotic leakage in patients undergoing McKeown esophagectomy

ObjectiveTo describe our experience of reducing anastomotic leakage, a problem that has not been properly solved. MethodsStarting in January 2020, we began implementing our integrated strategy (application of an esophageal diameter-approximated slender gastric tube, preservation of the fibrous tissue around the residual esophagus and thyroid inferior pole anastomosis) in consecutive patients undergoing esophagectomy without a nasogastric tube or a nasal-jejunum feeding tube. Additionally, the blood supply at the site of the anastomosis was evaluated with a near-infrared fluorescence thoracoscope after the completion of esophagogastric anastomosis in the integrated strategy group. ResultsOf 570 patients who were reviewed, 119 (20.9%) underwent the integrated strategy, and 451 (79.1%) underwent the conventional strategy. The rate of anastomotic leakage was 2.5% in the integrated strategy group and 10.2% in the conventional strategy group (p = 0.008). In the integrated strategy group, the site of most of the anastomotic blood supply was the residual esophagus dominant (82.4%), followed by the gastroesophageal dual-dominant (12.6%) and the gastric tube dominant (5.0%). The reconstruction route was more likely to be orthotopic in the integrated strategy group than in the conventional strategy group (89.9% vs. 38.6%, p = 0.004). Gastric dilation was identified in 3.4% of the patients in the integrated strategy group and in 21.1% in the conventional strategy group. ConclusionsPatients who underwent our proposed integrated strategy (Zhengzhou Strategy) during McKeown esophagectomy without a nasogastric tube or a nasal-jejunum feeding tube had a strikingly lower rate of anastomotic leakage and a relatively lower rate of postoperative complications, such as gastric tube dilation and delayed gastric emptying.

Comparison of two types of extension tubes for people with Parkinson’s disease in advanced treatment with levodopa–entacapone–carbidopa intestinal gel infusions: a prospective, crossover quality study

BackgroundWithin Parkinson’s disease (PD) management, a pivotal juncture often arises when individuals with PD (PwP) necessitate advanced therapies to stabilise symptom fluctuations and reduce off-periods, which are intrinsic to living...

Transumbilical Stapling Technic of OAGB.

Single-port or single-incision laparoscopic surgery (SILS) is esteemed for its efficacy in achieving superior postoperative cosmetic outcomes compared to the conventional laparoscopic approach (Behnia-Willison et al. in Aust N Z J Obstet Gynaecol 52:366-370, 2012; Rogula et al. in Obes Surg 24:1102-1108, 2014; Pitot et al. in Surg Endosc 28:3007-3011, 2014). The introduction of SILS for bariatric procedures can be attributed to the pioneering work of Saber in 2008, who initially applied this technique to laparoscopic sleeve gastrectomy (SG), followed by its utilization in laparoscopic adjustable gastric banding (AGB) (Saber et al. in Obes Surg 18:1338-1342, 2008;Nguyen et al. in Obes Surg 18:1628-1631, 2008). The inaugural application of SILS in Roux-en-Y gastric bypass (RYGB) was documented in 2009, employing a plastic reconstruction methodology. Acknowledging the intricate nature of complex bariatric interventions, we previously detailed a modified SILS approach termed the transumbilical two-site (TUTS) technique for RYGB, which was established as a standard procedure in 2010 (Lee et al. in Surg Obes Relat Dis. 8:208-13, 2012). At that juncture, a solitary article surfaced in 2010 elucidating the dimensions of the small gastric pouch as a mere 8-9cm, falling short of contemporary surgical requisites for optimal outcomes in one anastomosis gastric bypass (OAGB) (Tacchino et al. in Obes Surg 20:1154-1160, 2010). Notably, the TUTS technique, which was successfully implemented for RYGB, had hitherto not been extended to OAGB due to the complexities associated with creating a slender gastric tube spanning 25cm. In a pioneering development this year, we have devised a novel strategy to surmount this challenge. The present study is designed to expound upon the transumbilical stapling technique tailored to the unique demands of OAGB.

Magnetic resonance imaging of trickle flow

AbstractTrickle bed reactors (TBR) are widely used in the chemical industries. These reactors involve gas and liquid flow through a catalyst‐packed bed. For optimal TBR performance, it is crucial to achieve a uniform distribution of gas and liquid among the catalyst particles. However, in multitubular reactors with slender tubes, flow maldistribution near the tube walls is a common issue. Therefore, a comprehensive understanding of local phase and flow distribution is essential for designing and operating reactors with slender tubes. This article employs Magnetic Resonance Imaging (MRI) to characterize the three‐dimensional distribution of the two‐phase trickle flow within a slender tube. Three quantities are characterized: gas‐liquid‐solid distribution, particle wetting efficiency, and the flow field. Structure and flow MRI images are processed to calculate these quantities. Additionally, a novel postprocessing technique is introduced to determine the liquid distribution over individual particle surfaces. This distribution is determined at several axial and radial positions.

Experimental and numerical study on axial compression behavior of slender CFST columns with localized pitting corrosion damage

In order to investigate the axial compression behavior of slender circular concrete-filled steel tubes (CFSTs) with localized pitting corrosion damage, an experimental and numerical study was performed in this paper. In the experimental study, mechanically drilled cylindrical pits were employed to simulate localized pitting corrosion damage. Seven specimens were tested, with six specimens containing corrosion pits located at mid-height and one intact specimen. The experimental results showed that the localized pitting corrosion damage degraded the axial compression behavior of the specimens. Numerical models were developed and validated by the experimental results and used to consider the random characteristics of corrosion pits. A parametric analysis was then performed based on the validated numerical models. It was revealed that the ultimate strength of CFST was influenced by the location and dimensions of the pitting corrosion. Considering the random nature of localized pitting corrosion damage located at the midheight, practical calculation models for predicting the ultimate strength of CFSTs were put forward based on the methods provided in existing codes. On account of the obtained data pool, the predictions were verified against the results from the tests and parametric analysis. In addition, considering the random locations of the pitting region on the surface of the member, a method based on the controlling section was proposed to determine whether the corrosion should be considered and to calculate the ultimate strength.

A new internal surface polishing method for sub-millimeter slender tube with varying diameters

A new abrasive flow polishing method with a ferromagnetic blockage placed inside tube was proposed for finishing internal surface of slender tubes with varying diameters. A mathematic model was established to calculate the blockage's profile. Results indicate that the special designed ferromagnetic blockage provides an effective tool to adjust the flow velocity and pressure, and thus controlling local material removal. Axial tool marks were removed by rotating the workpiece during polishing. A uniform internal surface (Sa < 40 nm) was achieved when finishing a puncture needle with diameters ranging from 0.3 to 0.7 mm (initial Sa 600 - 1200 nm).

Various Flow in a Slender Tube: Mach Number and Domain Shape Influenced by Boundary Obstacles Via Small Disturbance Equations

With the exponential advancements in computer hardware and software in recent years, computational fluid dynamics (CFD) has emerged as a highly efficient alternative to traditional fluid mechanics studies. Its prowess in accurately predicting and analyzing flow mechanics has led to widespread adoption across diverse engineering disciplines. This research delves into a numerical analysis of flow conditions utilizing the small disturbance equation (SDE). The study bridges the gap between mathematical formulations and computational language, exemplified through Python code, by harnessing the successive over-relaxation (SOR) method, Neumann boundary conditions (BC), and the ghost point technique. The research underscores its predictions' precision in subsonic and supersonic scenarios by meticulously evaluating the resultant errors. This accuracy is further corroborated by examining overarching flow patterns and Mach number distributions. However, the program's outputs indicate a discernible lack of precision in the transonic case, with errors surpassing acceptable thresholds. This discrepancy is hypothesized to stem from potential mischaracterizations of points at the inflow and outflow boundaries. This study, thus, offers invaluable insights while also highlighting areas necessitating further refinement.

Experimental and numerical investigation on axial behavior of circular and square slender reinforced columns

To investigate the axial performance of slender concrete-filled steel tube (CFST) columns reinforced by outer steel tube and sandwiched concrete jackets, an axial compression test was conducted on 20 circular and square slender reinforced columns. The study aimed to examine the influence of the cross-sectional shape, steel content of the outer tube, the strength of sandwiched concrete, and slenderness ratio on the failure mode, load-displacement curves, and ultimate load. A comparative test on six slender CFST columns was also conducted. The test results showed that the local buckling degree of the outer steel tube in square reinforced columns was greater than that in circular reinforced columns, while the overall bending deformation was smaller. The influence of the sandwiched concrete strength on the load-displacement curve was weaker compared to the influence of the outer tube thickness and slenderness ratio. As the slenderness ratio increased, both the longitudinal and lateral strains of the specimens tended to decrease. The difference in strain between the tension and compression sides was more pronounced in circular reinforced columns than in square reinforced columns. The average SI values of circular and square reinforced specimens were 1.05 and 1.00, respectively, but the gap in SI values between the two types of reinforced columns is reduced as the slenderness ratio increases. Then, a numerical model on the slender reinforced columns was established by the finite element software ABAQUS. A good agreement was obtained between test results and simulation results. The mechanical mechanism of typical slender reinforced columns was further analyzed, including longitudinal stress contour map of concrete, the development of longitudinal stress of steel tube, as well as distribution of transverse confinement stress. A formula was subsequently proposed based on a design code to predict the load-bearing capacity of the retrofitted columns, the prediction results agreed well with the experimental data.

Flexural behaviour of optimised steel tubular beams partially filled with concrete

A partially concrete-filled steel tubular beam (PCFST) is proposed in this study to optimise the design and construction of the concrete-filled steel tubular beams (CFST). Concrete filling prevents the local buckling of the slender tubes. However, it is not needed in the beam’s tension zone. Therefore, in PCFST, concrete is filled in the compression zone while the tension zone is kept empty. In this paper, the flexural behaviour of the PCFST beam is studied experimentally and numerically. The ultimate moment resistance and flexural stiffness of PCFST are the same as CFST beams, while the weight reduction in PCFST is up to 60%. A finite element (FE) model is developed using ABAQUS software to investigate the effect of geometric and material properties of the PCFST beam on flexural behaviour. The FE model is validated by the present test results and the literature reports on CFST beams. Next, a parametric study is conducted to study the effect of concrete wall thickness in the web region, length-to-depth ratio, steel yield strength, concrete compressive strength, and beam shear span-to-depth ratio. The results show that the concrete filling is useful for slender steel tubular cross-sections rather than compact ones. A higher grade of concrete increases the beam ductility, while high-strength steel reduces the ductility. The results also show that the PCFST beam is more suitable for beam lengths where flexure is predominant than shear. Further, a flexural capacity equation is proposed for PCFST beams, and it agrees well with the test and numerical results. The reliability of the proposed equation is checked as per the recommendation in EN:1994–2004 and AISC 360–2016 code provisions.

Short Communication: Rediscovery of the Zamboanga peninsula endemic Boesenbergia longipetiolata (Ridl.) Merr. (Zingiberaceae) after a lapse of over a century, including an amended description and an updated distribution

Abstract. Yongco JE, Amparado OA, Naive MAK. 2023. Short Communication: Rediscovery of the Zamboanga peninsula endemic Boesenbergia longipetiolata (Ridl.) Merr. (Zingiberaceae) after over a century, including an amended description and an updated distribution. Biodiversitas 24: 6305-6309. Zamboanga Peninsula is one of the important sites for biodiversity studies in the Philippines. Despite that, there have been limited attempts for field explorations focusing on the floral diversity and plant inventories in the region, resulting in the scarcity of floristic data and has left many of its plant species, including their status, unknown. Included is Boesenbergia longipetiolata, a poorly known plant species belonging to the Zingiberaceae family, endemic to the Zamboanga Peninsula, Western Mindanao, Philippines and considered a long-lost species as its existence had not been reported since it was first collected in 1909. A meticulous examination of a specimen collected from a recent botanical exploration conducted in Mount Timolan Protected Landscape of Zamboanga Peninsula in July 2022 revealed the rediscovery of B. longipetiolata after a lapse of over a century. This species is unique among all other Philippine endemic Boesenbergia species by having a very long petiole and is closely similar to the Malay Peninsula endemic B. longipes but differs significantly by having lower stature, narrowly ovate to lanceolate lamina, a longer calyx and a slender corolla tube. In this study, an amended taxonomic description, including information on its geographical distribution and habitat, and a proposed conservation status are provided.

Performance of axially loaded slender circular CFSTs with random local corrosion

The performance of axially loaded slender circular concrete-filled steel tubes with random local corrosion was investigated in this paper through experimental and numerical study. Specifically, the randomness of corrosion included the random locations along the column height, irregular corrosion profile, and uneven corrosion surface. In the experimental study, machining defects are employed to simulate local corrosion, and five slender CFSTs were tested, with four containing the defect located at different member heights and one intact specimen. Additionally, a numerical study is conducted to consider the random nature of local corrosion in terms of random locations, irregular profiles, and uneven surfaces. A parametric analysis is then conducted, with varying parameters such as defect dimensions, locations, material strengths, steel ratio, and slenderness ratio. The analysis finds that the ultimate strength of the slender member is influenced by the location and dimensions of the local defect. Some sightly corrosion occurring in the column end has negligible influence on the performance of slender members. A method based on the controlled section is proposed for calculating the ultimate strength of slender circular CFSTs with random local corrosion, yielding accurate results.

Multi-pole magnetorheological shear thickening polishing on inner surface of aluminum alloy slender tubes

The aluminum alloys slender tubes with high surface quality are required to improve the components performance. The inner surface polishing of slender tubes becomes a challenge because of the machining space limitation. In this work, a multi-pole magnetorheological shear thickening polishing (MP-MSTP) method, combining the dual excitation of magnetorheological principles and shear thickening behavior, is proposed for aluminum alloy slender tubes polishing. The magnetic field generator was designed integrating four cylindrical Nd-Fe-B radial magnetic poles. The magnetic flux density is investigated in the polishing zone based on finite element analysis (FEA) and experimental measurements. Mathematical modeling of material removal rate (MRR) was established based on single abrasive particle. The feasibility of the MP-MSTP method for aluminum alloy slender tube was verified by computational fluid dynamics (CFD) simulation analysis and experimental measurements. Polishing experiments were carried out on the inner surface of aluminum alloy slender tubes to investigate the effect of various processing parameters on surface roughness, including carbonyl iron particles (CIPs) and silicon carbide (SiC) abrasive particle sizes, working gap and workpiece rotational speed. The surface roughness was reduced to 155 nm from the initial 480 nm under the optimal polishing parameters. A smooth surface without micro-convex peaks and deep scratches was obtained after 50 min polishing based on ultra-depth-of-field microscope and SEM observation.

Stability analysis of pultruded basalt fiber-reinforced polymer (BFRP) tube under axial compression

This study analyzed mechanical properties and stability of pultruded basalt fiber-reinforced polymer (BFRP) tubes under compressive axial loading for large-span space and truss structures applications. This study assessed the compressive strength of BFRP tubes with three different cross-sectional shapes and investigated the failure modes under compression with slenderness ratios ranging from 20 to 150. The results demonstrated that short BFRP tubes can achieve a compressive strength of up to 122.36 MPa with a compressive elastic modulus of 40.39 GPa. Three types of compressive failure modes were observed in the BFRP tubes, including local material, critical, and overall buckling failures. Furthermore, based on the analysis of experiment results, two design-oriented three-stage theoretical models were proposed for BFRP tubes with three different cross-sectional shapes. The proposed models were able to predict both the stress–strain and load-lateral deflection curves by taking into account the post-peak softening behavior of the stress–strain curve. In addition, a stability equation was also derived for predicting the compressive strength of slender BFRP tubes and was validated by experiments. The predictions derived from proposed models were consistent with experiment results.

Behaviour of axially-restrained slender steel tubes exposed to fire

The behaviour of axially-restrained slender steel tubes exposed to fire was studied. Fire tests and corresponding finite element (FE) simulations were conducted on four specimens with varying slenderness ratios and axial restraint stiffness. The accuracy of FE simulation was validated against the test results. Both the test and numerical results showed that the axially-restrained slender steel tubes buckled at much lower temperatures than steel columns. Continuous temperature elevation was then required to complete their buckling, because the steel maintains considerable stiffness at the buckling temperature. Parametric analysis was conducted based on FE simulations to investigate the effect of the slenderness ratio, axial restraint stiffness, and peak temperature on the behaviour of axially-restrained slender steel tubes exposed to fire. Empirical equations were established for the buckling temperature and post-fire residual lateral displacement using response surface methodology. These equations demonstrated a strong ability to fit the experimental data and predict the responses for new scenarios.

The available energy of trapped electrons: a nonlinear measure for turbulent transport

A collisionless plasma possesses a certain amount of ‘available energy’, which is that part of the thermal energy that can be converted into kinetic energy of plasma motion and electromagnetic fluctuations. In this paper we present a calculation of the available energy carried by trapped electrons in a slender non-omnigenous flux tube of plasma. This quantity is compared with gyrokinetic simulations of the nonlinear saturated radial energy flux resulting from turbulence driven by collisionless trapped-electron modes in various stellarators and a tokamak. The numerical calculation of available energy is fast and shows a strong correlation with the turbulent energy fluxes found in the gyrokinetic simulations. Indeed, the energy flux is found to be proportional to the available energy to the power of approximately $3/2$ , which is what one would expect from a simple argument. We furthermore investigate how available energy is distributed across different bounce wells, and it is found that deeply trapped electrons typically contribute most to the available energy. Finally, we investigate the dependence of available energy on gradient strength, and we find important differences between weakly and strongly driven regimes for stellarators and tokamaks.

A catalog of pressure and deformation profile for thin walled hyperelastic tubes conveying inertialess flow and undergoing large deformation

Slender tubes constituted of hyperelastic materials undergoing large deformations and conveying inertialess flow of Newtonian fluids are a model representation of several systems including those in soft robotics, biology and in industry. In this paper, we undertake a systematic study of this system. The tube’s hyperelastic behavior is modeled by five (5) different constitutive laws: Neo-Hookean, Mooney–Rivlin, Fung, Gent and Ogden. Invoking the principles of finite elasticity, we delineate the local pressure — deformation relationship for the tube for each of the hyperelastic models. The structural mechanical field of the tube is then coupled with fluid flow field, which is simplified using the principles of lubrication approximation. The resultant fluid–structure interaction problem then throws up a set of interesting results including the deformation and pressure profile across the tube, and tube laws for five (5) hyperelastic models. Analyzing these results, we posit that the behavior of Neo-Hookean and Mooney–Rivlin tubes is converse of Fung’s and Gent’s tubes; the latter show a strain hardening behavior whilst the former exhibit a strain softening one. A sensitivity analysis which underscores the relative importance of geometrical nonlinearity in the problem then follows.

BioKnit: development of mycelium paste for use with permanent textile formwork.

This paper presents significant advances in mycelium biofabrication using permanent knitted textile formwork and a new substrate formulation to dramatically improve the mechanical properties of mycelium-textile biocomposites suitable for large-scale components for use in construction. The paper outlines the biofabrication process, detailing the composition of mycocrete, a viscous mycelium substrate developed for use with permanent knitted formwork, and the injection process required to regulate the filling of slender tubes of fabric with mycocrete. The use of a permanent integrated knitted formwork shows promise as a composite system for use with mycelium to improve mechanical performance and enable complex shapes to be fabricated for lightweight construction. Results of mechanical testing show dramatic improvements in tensile, compressive and flexural strength and stiffness compared to conventional mycelium composites. The testing demonstrates the importance of both the mycocrete paste recipe and the knitted textile formwork. In addition, the paper highlights the advantages of the proposed biofabrication system with reference to the BioKnit prototype: a 1.8m high freestanding arched dome composed of very slender biohybrid knit-mycelium tubes. This prototype demonstrates the opportunity to utilize the potential for lightweight construction and complex form offered by a textile formwork with low environmental impact mycelium biomaterials. The combination of textiles and mycelium present a compelling new class of textile biohybrid composite materials for new applications within the construction sector.

Cryogenic spectroscopic imaging scanning tunnelling microscope in a water-cooled magnet down to 1.7 K

Spectroscopic-imaging scanning tunnelling microscope (SI-STM) in a water-cooled magnet (WM) at low temperature has long been desirable in the condensed matter physics area since it is crucial for addressing various scientific problems, such as the behaviour of Cooper electrons crossing Hc2 in a high-temperature superconductor. Here we report on the construction and performance of the first atomically resolved cryogenic SI-STM in a WM. It operates at low temperatures of down to 1.7 K and in magnetic fields of up to 22 T (the WM's upper safety limit). The WM-SI-STM unit features a high-stiffness sapphire-based frame with the lowest eigenfrequency being 16 kHz. A slender piezoelectric scan tube (PST) is coaxially embedded in and glued to the frame. A well-polished zirconia shaft is spring-clamped onto the gold-coated inner wall of the PST to serve both the stepper and the scanner. The microscope unit as a whole is elastically suspended in a tubular sample space inside a 1K-cryostat by a two-stage internal passive vibrational reduction system, achieving a base temperature below 2 K in a static exchange gas. We demonstrate the SI-STM by imaging TaS2 at 50 K and FeSe at 1.7 K. Detecting the well-defined superconducting gap of FeSe, an iron-based superconductor, at variable magnetic fields demonstrates the device's spectroscopic imaging capability. The maximum noise intensity at the typical frequency is 3 pA per square root Hz at 22 T, which is only slightly worse than at 0 T, indicating the insensitivity of the STM to harsh conditions. In addition, our work shows the potential of SI-STMs for use in a WM and hybrid magnet with a 50 mm-bore size where high fields can be generated.