Sandwich structures with tapered tubes as core:A quasi-static investigation

In this article,the experimental and finite element analysis is utilized to investigate the quasi-static compression features of sandwich constructions built with tapered tubes.3D printing technology was utilized to create the hollow centers of the tapering tubes,with and without corrugations.The results demonstrate that the energy absorption(EA)and specific energy absorption(SEA)of the single corrugated tapered tube sandwich are 51.6% and 19.8% higher,respectively,than those of the conical tube sandwich.Furthermore,the results demonstrate that energy absorbers can benefit from corrugation in order to increase their efficiency.Additionally,the tapered corrugated tubes'resistance to oblique impacts was studied.Compared to a straight tube,the tapered tube is more resistant to oblique loads and has a lower initial peak crushing force(PCF),according to numerical simulations.After conducting a parametric study,it was discovered that the energy absorption performance of the sandwich construction is significantly affected by the amplitude,number of corrugations,and wall thickness.EA and SEA of DTS with corrugation number of 8 increased by 17.4%and 29.6%,respectively,while PCF decreased by 9.2% compared to DTS with corrugation number of 10.

Crashworthiness Design and Multi-Objective Optimization of Bionic Thin-Walled Hybrid Tube Structures

Thin-walled structures are widely used in cars due to their lightweight construction and energy-absorbing properties.However,issues such as high initial stress and lowenergy-absorbing efficiency arise.This study proposes a novel energy-absorbing structure inwhich a straight tube is combinedwith a conical tube and a bamboo-inspired bulkhead structure is introduced.This configuration allows the conical tube to flip outward first and then fold together with the straight tube.This deformation mode absorbs more energy and less peak force than the conical tube sinking and flipping inward.Through finite element numerical simulation,the specific energy absorption capacity of the structure is increased by 26%compared to that of a regular circular cross-section tube.Finally,the impact resistance of the bionic straight tapered tube structure is further improved through multi-objective optimization,promoting the engineering application and lightweight design of hybrid cross-section tubes.

Modified intratympanic steroid therapy for sudden sensorineural hearing loss via tympanic tube and gelfoam as a salvage treatment

Background: Sudden sensorineural hearing loss(SSNHL) is a prevalent emergency in ear, nose, and throat practice. Previous studies have demonstrated that intratympanic steroid therapy(IST) can serve as a salvage treatment for SSNHL after the failure of systemic steroid therapy(SST).Objective: This study aimed to analyze the efficacy of modified IST involving the insertion of a tympanic tube and gelfoam as a salvage treatment for patients with SSNHL, and to explore its associated factors.Methods: Totally, 74 patients who were aged 22–81 years with SSNHL were enrolled and allocated to either the control group(n = 25) or the treatment group(n = 49) based on their treatment modalities. All patients received SST lasting for at least 7 days. Subsequently, patients in the treatment group, after SST failure, underwent IST twice a week for 2–6 weeks, while the control group did not. Efficacy was assessed by the improvement in pure tone average at the affected frequency at the beginning and end of IST.Results: Hearing improvement in all patients after IST in the treatment group was 9.71 ± 14.84 dB, with significant improvement at affected frequencies(250-8000 Hz) compared with the control group(P < 0.05). The findings indicated the duration from the onset of SSNHL to the beginning of IST as an independent factor for pure tone average improvement after treatment(P = 0.002), whereas age, duration of SST, and time of IST were not(P > 0.05).Conclusion: The modified IST was demonstrated to be a safe and effective method as a salvage treatment for SSNHL. This study explored the efficacy of a modified IST approach, incorporating the utilization of tympanic tubes and gelfoam as key components. The findings underscore the advantages of gelfoam as a strategic drug carrier placed in the round window niche. By minimizing drug loss, extending action time, and increasing perilymph concentration, gelfoam enhances the therapeutic impact of IST, contributing to improved hearing outcomes in patients with SSNHL.

Analysis and Optimization of the Electrohydraulic Forming Process of Sinusoidal Corrugation Tubes

Aluminum alloy thin-walled structures are widely used in the automotive industry due to their advantages related to light weight and crashworthiness.They can be produced at room temperature by the electrohydraulic forming process.In the present study,the influence of the related parameters on the forming quality of a 6063 aluminum alloy sinusoidal corrugation tube has been assessed.In particular,the orthogonal experimental design(OED)and central composite design(CCD)methods have been used.Through the range analysis and variance analysis of the experimental data,the influence degree of wire diameter(WD)and discharge energy(DE)on the forming quality was determined.Multiple regression analysis was performed using the response surface methodology.A prediction model for the attaching-die state coefficient was established accordingly.The following optimal arrangement of parameters was obtained(WD=0.759 mm,DE=2.926 kJ).The attaching-die state coefficient reached the peak value of 0.001.Better optimized wire diameter and discharge energy for a better attaching-die state could be screened by CCD compared with OED.The response surface method in CCD was more suitable for the design and optimization of the considered process parameters.

Creep rupture properties and microstructure stability of the GH984G alloy tube

GH984G alloy is a significant candidate material for 650-700℃ ultra-supercritical coal-fired generating units.In this paper,creep rupture properties and microstructure stability of the GH984G alloy tube were studied,and the findings indicated excellent creep rupture properties at 700℃.Furthermore,the extrapolated strength for 100000 h was found to be 153.8 MPa,which satisfies the requirements for the long-term performance of high-temperature materials in power stations.Aging at 700℃ with the extension of time,the grain boundary carbides and the particle size of the γ′phase on the matrix gradually coarsen,but its spherical morphology remains uniformly distributed.However,no harmful phase precipitates were found even after aging at 700℃ for up to 19144 h.Excellent microstructure stability guarantees the 700℃ creep rupture properties of the GH984G alloy tube.

Impact Containment Barriers with Geotextile Tubes

Recently, tragic tailings dam collapses in Brazil have caused deaths and major destruction and the need to develop technologies capable of preventing damage to people and the environment. Brazilian tailings dams are in a situation of uncertainty due to new legislation that even requires decommissioning, an activity that involves many problems and where the risk of failure is the main one. An impact containment structure downstream of these dams can be effective and geotextile tubes, in a new approach, have emerged as an option with advantages in terms of execution, costs and safety. The technology is versatile and can bring many benefits such as the reuse of tailings or filling with low-energy or reused materials. In this research, geotextile tubes were tested as free containment barriers, experiencing impacts in reduced models. The safety factor for the stability of the structure was constructed using an equation which is the ratio between the self-weight of the barrier structure and its coefficient of static friction and the impact pressure, where the data showed an adequate correlation which suggests the viability of mitigating risks.

The rat eustachian tube:Anatomical, histological, and radiological features

Purpose: This study investigated the anatomical and histological characteristics of the rat Eustachian tube(E-tube)and the feasibility of Eustachian tubography in a rat model.Materials and methods: Fifteen male Wistar rats were used in this study, and the bilateral E-tubes of each rat were examined. Ten E-tubes were used for anatomical studies, another ten for histological analysis, and the other ten for Eustachian tubography. Five rats were euthanized and decapitated, and ten E-tubes were dissected to describe the anatomy of the E-tube. Ten E-tube specimens obtained from five other rats were sectioned to investigate Etube histology. Eustachian tubography was performed on the bilateral E-tubes of the other five rats using the trans-tympanic approach.Results: The rat E-tubes consisted of bony and membranous parts. Cartilage and bone tissue covered only the bony part. The E-tubes’ mean diameter and overall length were 2.97 mm and 4.96 mm, respectively. The tympanic orifices’ mean diameter was 1.21 mm. The epithelium of E-tubes was mainly composed of pseudostratified ciliated and goblet cells. Eustachian tubography was successfully performed on both sides of the E-tube for each rat.The technical success rate was 100%, the average running time was 4.9 min, and no procedure-related complications occurred. On tubography images, the E-tube, tympanic cavity, and nasopharynx could be identified because of the visualization of bony landmarks.Conclusion: In this study, we described the anatomical and histological features of rat E-tubes. With the aid of these findings, E-tube angiography was successfully performed using a transtympanic approach. These results will facilitate further investigation of E-tube dysfunction.

Experimental and Numerical Studies on Sea Sand Concrete Filled Stainless Steel Tube with Inner FRP Tube Subjected to Axial Compression

Since fibre-reinforced polymer(FRP) and stainless steel(SS) offer advantages of corrosion resistance and hybrid confinement, this study proposed a new type of composite column: sea sand concrete(SSC)-filled SS tubular columns with an inner FRP tube(CFSTFs) to help exploit abundant ocean resources in marine engineering. To study compressive behaviours of these novel members, eight CFSTFs and two SSC-filled SS tubular columns(CFSTs)were tested under axial compression. Their axial load-displacement curves, axial load-strain curves in SS or FRP tubes were obtained, and influences of key test parameters(the existence of glass FRP(GFRP) tubes, steel tube shapes, and GFRP tube thicknesses and diameters) were discussed. Further, specimen failure mechanism was analyzed employing the finite element method using ABAQUS software. Test results confirmed the excellent ductility and load-bearing capacity of CFSTFs. The existence of GFRP tubes inside can postpone SS tube buckling, and the content of inner FRP tubes, particularly increasing diameters, was found to improve compressive behaviours. GFRP contents helped develop the second elastic-plastic stage of the load-displacement curves. Furthermore, the bearing capacity of CFSTFs with a circular cross-section was approximately 26% higher than that with a square cross-section, and this difference narrowed with the increase in GFRP ratios.

A comparative single-pulse shock tube experiment and kinetic modeling study on pyrolysis of cyclohexane,methylcyclohexane and ethylcyclohexane

The pyrolysis of cyclohexane,methylcyclohexane,and ethylcyclohexane have been studied behind reflected shock waves at pressures of 5 and10 bar and at temperatures of 930-1550 K for 0.05%fuel diluted by Argon.A single-pulse shock tube(SPST)is used to perform the pyrolysis experiments at reaction times varying from 1.65 to 1.74 ms.Major products are obtained and quantified using gas chromatography analysis.A flame ionization detector and a thermal conductivity detector are used for species identification and quantification.Kinetic modeling has been performed using several detailed and lumped chemical kinetic mechanisms.Differences in modeling results among the kinetic models are described.Reaction path analysis and sensitivity analysis are performed to determine the important reactions controlling fuel pyrolysis and their influence on the predicted concentrations of reactant and product species profiles.The present work provides new fundamental knowledge in understating pyrolysis characteristics of cyclohexane compounds and additional data set for detailed kinetic mechanism development.

Identification and functional analysis of arabinogalactan protein expressed in pear pollen tubes

Arabinogalactan proteins(AGPs)are widely distributed in the plant kingdom and play a vital role during the process of plant sexual reproduction.In this study,we performed a comprehensive identification of the PbrAGPs expressed in pear pollen and further explored their influences on pollen tube growth.Among the 187 PbrAGPs that were found to be expressed in pear pollen tubes,38 PbrAGPs were specifically expressed in pollen according to the RNA-seq data.The PbrAGPs were divided into two groups of highly expressed and specifically expressed in pear pollen.We further tested their expression patterns using RT-PCR and RT-qPCR.Most of the PbrAGPs were expressed in multiple tissues and their expression levels were consistent with reads per kilobase per million map reads(RPKM)values during pollen tube growth,implying that PbrAGPs might be involved in the regulation of pear pollen tube growth.We also constructed phylogenetic trees to identify the functional genes in pear pollen tube growth.Therefore,19 PbrAGPs(PbrAGP1 to PbrAGP19)were selected to test their influences on pollen tube growth.Recombinant proteins of the 19 PbrAGP-His were purified and used to treat pear pollen,and 11 of the PbrAGP-His recombinant proteins could promote pear pollen tube growth.Additionally,pollen tube growth was inhibited when the expression levels of PbrAGP1 and PbrAGP5 were knocked down using an antisense oligonucleotide assay.PbrAGP1 and PbrAGP5 were localized in the plasma membrane and might not alter the distribution of pectin in the pollen tube.In summary,this study identified the PbrAGPs expressed in pear pollen and lays the foundation for further exploring their functions in pollen tube growth.

Effects of tube cross-sectional shapes on flow pattern, liquid film and heat transfer of n-pentane across tube bundles

The heat transfer of hydrocarbon refrigerant across tube bundles have been widely used in refrigeration.Three-dimensional simulation model using volume of fluid(VOF) was presented to study the effects of tube shapes on flow pattern, film thickness and heat transfer of n-pentane across tube bundles, including circle, ellipse-shaped, egg-shaped and cam-shaped tube bundles. Simulation results agree well with experimental data in the literature. The liquid film thickness of sheet flow and heat transfer for different tube shapes were obtained numerically. The flow pattern transition occurs lower vapor quality for ellipse-shaped tube than other tube shapes. For sheet flow, the liquid film on circle tube and ellipseshaped tube is symmetrically distributed along the circumferential direction. However, the liquid film on egg-shaped tube at circumferential angles(θ) = 15°–60° is thicker than θ = 135°–165°. The liquid film on cam tube at θ = 15°–60° is slightly thinner than θ = 135°–165°. The liquid film thickness varies from thinner to thicker for ellipse-shaped, cam-shaped, egg-shape and circle within θ = 15°–60°. The effect of tube shape is insignificant on thin liquid film thickness. Ellipse-shaped tube has largest heat transfer coefficient for sheet flow. In practical engineering, the tube shape could be designed as ellipse to promote heat transfer.

Numerical simulation of flow and heat transfer of n-decane in sub-millimeter spiral tube at supercritical pressure

The flow and heat transfer characteristics of n-decane in the sub-millimeter spiral tube(SMST) at supercritical pressure(p = 3 MPa) are studied by the RNG k-ε numerical model in this paper. The effects of various Reynolds numbers(Re) and structural parameters pitch(s) and spiral diameter(D) are analyzed.Results indicate that the average Nusselt numberNu and friction factorNu increase with an increase in Re, and decrease with an increase in D/d(tube diameter). In terms of the structural parameter s/d, it is found that as s/d increases, the Nu first increase, and then decrease. and the critical structural parameter is s/d = 4. Compared with the straight tube, the SMST can improve Nu by 34.8% at best, while it can improve Nu by 102.1% at most. In addition, a comprehensive heat transfer coefficient is applied to analyze the thermodynamic properties of SMST. With the optimal structural parameters of D/d = 6 and s/d = 4, the comprehensive heat transfer factor of supercritical pressure hydrocarbon fuel in the SMST can reach 1.074. At last, correlations of the average Nusselt number and friction factor are developed to predict the flow and heat transfer of n-decane at supercritical pressure.

CFD-Based Optimization of a Shell-and-Tube Heat Exchanger

The main objective of this study is the technical optimization of a Shell-and-Tube Heat Exchanger(STHE).In order to do so,a simulation model is introduced that takes into account the related gas-phase circulation.Then,simulation verification experiments are designed in order to validate the model.The results show that the tem-peraturefield undergoes strong variations in time when an inlet wind speed of 6 m/s is considered,while the heat transfer error reaches a minimum of 5.1%.For an inlet velocity of 9 m/s,the heat transfer drops to the lowest point,while the heat transfer error reaches a maximum,i.e.,9.87%.The pressure drop increasesfirst and then decreases with an increase in the wind speed and reaches a maximum of 819 Pa under the 9 m/s wind speed con-dition.Moreover,the pressure drops,and the heat transfer coefficient increases with the Reynolds number.

Theoretical and Experimental Analysis of Heat Transfer and Condensation in Micro-Ribbed Tubes

The thermal transmission coefficient for a micro-ribbed tube has been determined using theoretical relationships and the outcomes of such calculations have been compared with experiments conducted using a R1234yf refrigerant undergoing condensation.In particular four theoretical single-phase flow and three multi-phase flow models have been used in this regard.The experimental results show that:the Oliver et al.criterion equation overestimates the experimental results as its accuracy is significantly affected by the specific conditions realized inside micro-fin tubes;the Miyara et al.criterion equation prediction error is less than 15%;the Cavallini et al.approach gives the highest prediction accuracy;the Goto et al.model overestimates the test data.Such results are critically discussed and some indications for the improvement of such models are provided.

A Comprehensive Review of the Influence of Heat Exchange Tubes on Hydrodynamic,Heat,and Mass Transfer in Bubble and Slurry Bubble

Bubble and slurry bubble column reactors(BCRs/SBCRs)are used for various chemical,biochemical,and petro-chemical applications.They have several operational and maintenance advantages,including excellent heat and mass transfer rates,simplicity,and low operating and maintenance cost.Typically,a catalyst is present in addition to biochemical processes where microorganisms are used to produce industrially valuable bio-products.Since most applications involve complicated gas-liquid,gas-liquid-solid,and exothermic processes,the BCR/SBCR must be equipped with heat-exchanging tubes to dissipate heat and control the reactor’s overall performance.In this review,past and very recent experimental and numerical investigations on such systems are critically dis-cussed.Furthermore,gaps to befilled and critical aspects still requiring investigation are identified.

3D Grid of Carbon Tubes with Mn3O4-NPs/CNTs Filled in their Inner Cavity as Ultrahigh-Rate and Stable Lithium Anode

Transition metal oxides are regarded as promising candidates of anode for next-generation lithium-ion batteries(LIBs)due to their ultrahigh theoretical capacity and low cost,but are restricted by their low conductivity and large volume expansion during Li^(+)intercalation.Herein,we designed and constructed a structurally integrated 3D carbon tube(3D-CT)grid film with Mn_(3)O_(4)nanoparticles(Mn_(3)O_(4)-NPs)and carbon nanotubes(CNTs)filled in the inner cavity of CTs(denoted as Mn_(3)O_(4)-NPs/CNTs@3D-CT)as high-performance free-standing anode for LIBs.The Mn_(3)O_(4)-NPs/CNTs@3D-CT grid with Mn_(3)O_(4)-NPs filled in the inner cavity of 3D-CT not only afford sufficient space to overcome the damage caused by the volume expansion of Mn_(3)O_(4)-NPs during charge and discharge processes,but also achieves highly efficient channels for the fast transport of both electrons and Li+during cycling,thus offering outstanding electrochemical performance(865 mAh g^(-1)at 1 A g^(-1)after 300 cycles)and excellent rate capability(418 mAh g^(-1)at 4 A g^(-1))based on the total mass of electrode.The unique 3D-CT framework structure would open up a new route to the highly stable,high-capacity,and excellent cycle and high-rate performance free-standing electrodes for highperformance Li-ion storage.

An Evaluation to the Performance of Evacuated Tube Solar Heaters for Arid and Hot Areas

Solar energy applications could be the best alternative to the conventional fuels for the purposes of domestic,water and space heating and some industries in the sunny,arid,and hot areas.In the present study,the performance of an evacuated tube solar heater for water heating for months of February and March was experimentally investigated.This was performed in a hot and arid area(Nasiriya City,South of Iraq).A solar heater with ten evacuated tube solar collectors with a capacity of 100 liter was used in the experiments.Each evacuated tube had a length of 1.8m with an outside diameter of 8 cm.It was observed that for the two selected months,water temperature of the solar heater reached a maximum more than 70°C during sunny days with no heat extraction from the tank of the solar heater.Moreover,heat was extracted from the solar collector with four different flowrates 0.5,0.75,1,and 1.25 l/min,respectively.The results showed that temperature of the solar heater behaved differently from the static situation.When the heat extraction begun,there was a gradual and noticeable decrease in the water temperature of the heater.The observed decrease was slight with the lowest flowrate(0.25 l/m)and becomes sharp with the highest flowrate(1.25 l/min).However,water temperature of the solar heater remained higher than 40°C for the investigated flowrates except the case of 1.25 l/min.The results showed that evacuated tube solar heater can work efficiently in arid and hot areas in winter and spring seasons when the conditions of solar radiation are suitable.

The Interest of Endoscopy in the Diagnosis of Fallopian Tubes Diseases at the Yaoundé Gyneco-Obstetric and Pediatric Hospital (Ygoph)

Introduction: Fallopian diseases are often implicated in female infertility. Several radiological and surgical explorations have been proposed in order to evaluate the severity of lesions found in utero-adnexal pathology. Among tools that are used to investigate such pathologies, we have ultrasound, hysterosalpingography and endoscopy. But, in many developing countries like Cameroon, the usage of endoscopy in gynecology is not yet known by many practicians. The objective of our study was to show the interest of endoscopy in the diagnosis of fallopian tube pathologies. Methodology: We conducted a cross-sectional and descriptive study from March 1st, 2017 to May 31st, 2017 at the Gyneco-Obstetrics and Pediatric department of our Hospital. We included all women who presented infertility and underwent ultrasound, hysterosalpingography (HSG) and endoscopy at the Yaoundé Gyneco-obstetrics Hospital. We analyzed epidemiological parameters, clinics, ultrasound, hysterosalpingography and endoscopic finding. We used Cohen’s Kappa test to determine the correlation between HSG/endoscopy and ultrasound/endoscopy in the diagnosis of fallopian tube pathologies. The threshold was significant for a K-value > 0.20. Results: We got a sample of 156 women;the mean age was 32.6 ± 4.5 years. The Secondary infertility dominated in 66.7% of cases;31.1% of women presented a past medical history of sexually transmitted infections and 41.7% did abortions before. Endoscopic lesions were dominated by a fallopian obstruction in 54.5% of cases, 8.3% of adhesions, 33.9% of women presented uterine myomas, 37.8% of ovarian cysts and 1.3% of pelvic endometriosis. The K-values between HSG and endoscopy for distal and proximal tube obstructions were significant with respective thresholds of 0.25 and 0.30. The K-value between ultrasound and endoscopy was not significant with a threshold of 0.015 for the tubal hydrosalpinx. Conclusion: Endoscopy assessment appears as the most efficient tool to investigate fallopian tube diseases.

Magneto-Hydrodynamic Flow of an Incompressible Fluid in a Collapsible Elastic Tube with Mass and Heat Transfer

The aim of this study is to examine unsteady incompressible Magnetohydrodynamic fluid flow together with soret and dufour effects on mass and heat transfer through a collapsible elastic tube. The governing equations are continuity equation, momentum equation, energy equation and concentration equation. The velocity, temperature and concentration profiles together with heat and mass transfer rate were determined. The system of nonlinear partial differential equations governing the flow solved numerically by applying collocation method and implemented in MATLAB. The numerical solution of the profiles displayed both by graphically and numerically for different values of the physical parameters entering into the problem. The effects of varying various parameters such as Reynolds number, Hartmann number, Soret number, Dufour number and Prandtl number on velocity, temperature and concentration profiles also the rate of heat and mass transfer are discussed. The study is significant because heat and mass transfer mechanisms with the soret and dufour effects considerations play an important role due to its wide range of application including but not limited to medical fields, biological sciences and other physical sciences where collapsible tubes are applied.

Comparison of the conventional tube and erythrocyte-magnetized technology in titration of red blood cell alloantibodies

BACKGROUND Erythrocyte alloantibodies are mainly produced after immune stimulation,such as blood transfusion,pregnancy,and transplantation,and are the leading causes of severe hemolytic transfusion reactions and difficulty in blood grouping and matching.Therefore,antibody screening is critical to prevent and improve red cell alloantibodies.Routine tube assay is the primary detection method of antibody screening.Recently,erythrocyte-magnetized technology(EMT)has been increasingly used in clinical practice.This study intends to probe the application and efficacy of the conventional tube and EMT in red blood cell alloantibody titration to provide a reference for clinical blood transfusion.AIM To investigate the application value of conventional tube and EMT in red blood cell alloantibody titration and enhance the safety of blood transfusion practice.METHODS A total of 1298 blood samples were harvested from blood donors at the Department of Blood Transfusion of our hospital from March 2021 to December 2022.A 5 mL blood sample was collected in tubing,which was then cut,and the whole blood was put into a test tube for centrifugation to separate the serum.Different red blood cell blood group antibody titers were simultaneously detected using the tube polybrene test,tube antiglobulin test(AGT),and EMT screening irregular antibody methods to determine the best test method.RESULTS Simultaneous detection was performed through the tube polybrene test,tube AGT and EMT screening irregular antibodies.It was discovered that the EMT screening irregular antibody method could detect all immunoglobulin G(IgG)and immunoglobulin M(IgM)irregular antibodies,and the results of manual tube AGT were satisfactory,but the operation time was lengthy,and the equipment had a large footprint.The EMT screening irregular antibody assay was also conducted to determine its activity against type O Rh(D)red blood cells,and the outcomes were satisfactory.Furthermore,compared to the conventional tube method,the EMT screening irregular antibody method was more cost-effective and had significantly higher detection efficiency.CONCLUSION With a higher detection rate,the EMT screening irregular antibody method can detect both IgG and IgM irregular antibodies faster and more effectively than the conventional tube method.