Off-label-use of sulfur-hexafluoride in voiding urosonography for diagnosis of vesicoureteral reflux in children:A survey on adverse events

AIM To evaluate the risk profile of sulfur hexafluoride in voiding urosonography(VUS) based on a large cohort of children.METHODS Since 2011 sulfur hexafluoride(SH,SonoV ue?,Bracco,Italy) is the only ultrasound contrast available in the European Union and its use in children has not been approved.Within a 4-year-period,531 children with suspected or proven vesicoureteral reflux(f/m = 478/53; mean age 4.9 years; 1 mo-25.2 years) following parental informed consent underwent VUS with administration of 2.6 ± 1.2 mL SH in a two-center study.A standardizedtelephone survey on adverse events was conducted three days later.RESULTS No acute adverse reactions were observed.The survey revealed subacute,mostly self-limited adverse events in 4.1%(22/531).The majority of observed adverse events(17/22) was not suspected to be caused by an allergic reaction: Five were related to catheter placement,three to reactivated urinary tract infections,five were associated with perineal disinfection before voiding urosonography or perineal dermatitis and four with a common cold.In five patients(0.9%) hints to a potential allergic cause were noted: Perineal urticaria was reported in three interviews and isolated,mild fever in two.These were minor self-limited adverse events with a subacute onset and no hospital admittance was necessary.Ninety-six point two percent of the parents would prefer future VUS examinations with use of SH.CONCLUSION No severe adverse events were observed and indications of self-limited minor allergic reactions related to intravesical administration of SH were reported in less than 1%.

Uncommon cause of voiding dysfunction in a female patient-vaginal abscess: A case report

BACKGROUND Vaginal abscess is a treatable disease and should be considered in female patients with voiding difficulties and perineal tenderness. There are no reported cases of vaginal abscess causing voiding dysfunction in the absence of a previous surgery. Early diagnosis and drainage of vaginal abscesses may lead to excellent outcomes.CASE SUMMARY We presented a case of vaginal abscess that caused voiding dysfunction without surgery history. A 64-yearold woman had a past history of type 2 diabetes mellitus. She came to our clinic following urinary difficulty with perineal tenderness. Bladder ultrasonography revealed a pelvic cystic lesion with a mass effect on the bladder. The presence of a vaginal abscess was suspected following pelvic examination and transvaginal ultrasound.After transvaginal drainage of the vaginal abscess and a full course of antibiotic treatment, she recovered well without any urination symptoms. CONCLUSION Voiding dysfunction caused by vaginal abscess is rare but should be considered in female patients with perineal tenderness.

A Feasibility Study of an Individualized Voiding Program in Japan to Improve the Sense of Control in Older People with Functional Urinary Incontinence

Purpose: This study intended to assess the feasibility of an individualized voiding program in Japan aimed at improving the sense of micturition control in older people with functional urinary incontinence. Method: Following the interview guide, FGIs were conducted in two groups (4 - 6 participants) consisting of nurses and care workers with more than 5 years of experience as practitioners of urination care. Data were analyzed using a qualitative descriptive approach. Results: We determined that the program purpose is to “enable caregivers to work as a well-coordinated team to humanely facilitate excretion independence in older people, which is essential for living with dignity”, as this confirmed the importance of maintaining the sense of micturition control in older people for their well-being. In the program outline, we extracted the following five categories: 1) setting selection criteria for recipients considering the status of micturition induction, 2) careful collection of information and assessment of lower urinary tract symptoms in older people in case of environmental changes, 3) examination of methods used for assessing lower urinary tract symptoms according to the facility environment, 4) confirmation of the recipient’s micturition habits and request for assistance, and 5) conducting necessary examination for setting the intervention period and evaluation period according to the target condition. The feedback on the program guide was summarized in the statement—specific successful cases help frame and implement the micturition induction plan. Conclusion: We confirmed the feasibility of the micturition induction plan for improving the sense of control in older people with functional urinary incontinence. Upon evaluating the program guide, we deemed that referring to specific successful cases helps frame and implement the micturition induction plan. It is extremely important to verify the effectiveness of the program going forward.

Botulinum Toxin-A for the Treatment of Voiding Dysfunction: Our Initial Experience

Objective: Evaluation of Botulinum Toxin-A (BTX-A) as an alternative treatment option in patients whom previous treatments were failed. Methods: Between March 2005 and September 2006, a total 19 patients;16 patients with overactive bladder (5 neurologic, 11 idiopathic), 2 with nocturnal enuresis, 1 with interstitial cystitis, intravesical BTX-A injection was applied. Except one patient, 18 patients with a median age 46 (20 - 80) were registered to the study. Patients were examined at postoperative 3 weeks and 6 months with ICIQ-SF (International Consultation on Incontinence Questionnaire-Short Form) and satisfaction forms used in our clinic. Results: The median follow-up time was 16 months (6 - 18). When evaluated according to diagnosis, symptoms were improved 100% in neurologic overactive bladder (5/5), 80% in idiopathic overactivity (8/10), 50% in nocturnal enuresis (1/2). In one patient with interstitial cystitis there was no improvement. Median efficiency time of BTX-A treatment was 6 months (1 - 17). At 3 weeks and 6 months after the treatment, ICIQ-SF score was decreased to 3.6 and 7.5 respectively from preoperative level of 18.7. Quality of life scores at preoperative, 3 week and 6 months were 9.7, 2.7 and 4.3 respectively. Except 3 patients with overactive neurologic bladder because of spinal cord injury, symptoms of patients with pollacuria and nocturia decreased at 3. week. Even if these rates increased at 6 months they still were significantly less than preoperative status. The spinal cord injured 3 patients had clean intermittent catheterization per 1 hour and had urinary incontinence between the catheterizations preoperatively, however at 3 weeks and 6 months the intervals of catheterisations was 4 hours and 3 hours respectively and also the urinary incontinance between the catheterisations improved. At patient satisfactions, 78% of patients declared that they were pleased and underwent the procedure again and will recommend it to their relatives with similar problems. One patient had a complication as tansient weakness on her legs. Conclusion: BTX-A injections provide an alternative treatment before surgery at overactive bladder especially for those who doesn’t response to medical treatment or cannot use antimuscarinics because of their side effects. Further studies with a greater number of patients are needed for determining the effectiveness of BTX-A on patients with voiding dysfunctions.

Comparative study of conventional urosonography without contrast enhancement and x-ray voiding cystourethrography for diagnosis of vesicoureteral reflux in children

Background:Vesicoureteral reflux is the most common urinary congenital anomaly in children.Given the risk associated with radiation exposure there has been an increasing need for radiation-free method in the diagnosis and follow-up of the vesicoureteral reflux.The aim of our study is to compare conventional urosonography without contrast enhancement and x-ray voiding cystourethrography.Patients and Methods:Children with recurrent urinary tract infection with suspected vesicoureteral reflux were included to the study.Vesicoureteral reflux is demonstrated and graded by x-ray voiding cystourethrography.DMSA is used for the evaluation of renal scar.Conventional sonographic procedure was performed in all patients.Ureterovesical junction insertion angle was evaluated.The diameter and length of the ureterovesical junction were also measured.Results:268 children enrolled to the study.Vesicoureteral reflux was demonstrated in 62 children by x-ray voiding cystourethrography.Ureterovesical junction insertion angle measurement had a statistically significant relation for right and left vesicoureteral reflux presence(right:r:.646,p:.01 and left:r:.446,p:.01).Diagnosis sensitivity of vesicoureteral reflux with conventional ultrasonography is 95.10%and specificity is 81%(Youden’s index 76.1%)for the cutoff value of the ureterovesical junction insertion angle is 28.6 degrees.Positive predictive value is 87.2%,negative predictive value is 94.73%and diagnostic accuracy is 86.29%with conventional ultrasonography.Conclusions:Measurement of ureterovesical junction insertion angle,length and diameter by conventional urosonography is an easy accessible and cheap technique with high sensitivity and specificity for the diagnosis and followup of the vesicoureteral reflux without exposure to ionizing radiation.

Urodynamic analysis and treatment of male Parkinson＇s disease patients with voiding dysfunction

Background Parkinson＇s disease （PD） is an extrapyramidal neurological disorder.Urinary symptoms are frequently present in patients affected by PD.Symptoms such as urgency,frequency,nocturia,and urge incontinence significantly impact the patient＇s quality of life.We attempted to investigate the urodynamic changes and treatment of male PD patients with voiding dysfunction by means of a review.Methods Comprehensive urodynamic examinations were performed in 141 male patients with PD associated with voiding dysfunction.Appropriate treatments were given to subgroups that were divided based on test results,and the changes in urodynamic parameters as well as the treatment efficacy were observed.Results Detrusor hyperreflexia without bladder outlet obstruction （BOO） was observed in 35 patients,who exhibited significant improvements in the international prostate symptom score （IPSS）,maximum flow rate （Qmax）,bladder volume at the first desire to void,post-void residual （PVR）,and bladder compliance.Detrusor hyperreflexia associated with BOO was observed in 59 patients.The patients exhibited significant improvements in IPSS,Qmax,PVR,and bladder compliance.Detrusor dysfunction without BOO was observed in 19 patients,for whom the IPSS and the bladder volume at the first desire to void were improved after treatment.Detrusor dysfunction with BOO was found in 28 patients,with no significant improvement in the urodynamic parameters after the treatment.Conclusions Urodynamic examination is recommended for male Parkinson＇s disease patients with voiding dysfunction.Early and effective treatment can improve the bladder function and quality of life of these patients.

Work Capacity of the Bladder During Voiding： A Novel Method to Evaluate Bladder Contractile Function and Bladder Outlet Obstruction

Background： Work in voiding （WIV） of the bladder may be used to evaluate bladder status throughout urination rather than at a single time point. Few studies, however, have assessed WIV owing to the complexity of its calculations. We have developed a method of calculating work capacity of the bladder while voiding and analyzed the associations of bladder work parameters with bladder contractile function and bladder outlet obstruction （BOO）. Methods： The study retrospectively evaluated 160 men and 23 women, aged 〉40 years and with a detrusor pressure at maximal flow rate （PdetQmax） of ≥40 cmH2O in men, who underwent urodynamic testing. The bladder power integration method was used to calculate WIV; WIV per second （WIV/t） and WIV per liter of urine voided （WIV/v） were also calculated. In men, the relationships between these work capacity parameters and PdetQmax and Abrams-Griffiths （AG） number were determined using linear-by-linear association tests, and relationships between work capacity parameters and BOO grade were investigated using Spearman＇s association test. Results： The mean WIV was 1.15 ± 0.78 J and 1.30 ± 0.88 J, mean WIV/t was 22.95 ± 14,45 mW and 23.78 ± 17.02 mW, and mean WIV/v was 5.59 ± 2.32 J/L and 2.83 ± 1.87 J/L in men and women, respectively. In men, WIV/v showed significant positive associations with PdetQmax （r = 0.845, P = 0.000）, AG number （r = 0.814, P = 0.000）, and Schafer class （r = 0.726, P = 0.000）. Conversely, WIV and WIV/t showed no associations with PdetQmax or AG number. In patients with BOO （Schafer class 〉 II）, WIV/v correlated positively with increasing BOO grade. Conclusions： WIV can be calculated from simple urodynamic parameters using the bladder power integration method. WIV/v may be a marker of BOO grade, and the bladder contractile function can be evaluated by WIV and WIV/t.

A photogrammetric approach for quantifying the evolution of rock joint void geometry under varying contact states

Accurate measurement of the evolution of rock joint void geometry is essential for comprehending the distribution characteristics of asperities responsible for shear and seepage behaviors.However,existing techniques often require specialized equipment and skilled operators,posing practical challenges.In this study,a cost-effective photogrammetric approach is proposed.Particularly,local coordinate systems are established to facilitate the alignment and precise quantification of the relative position between two halves of a rock joint.Push/pull tests are conducted on rock joints with varying roughness levels to induce different contact states.A high-precision laser scanner serves as a benchmark for evaluating the photogrammetry method.Despite certain deviations exist,the measured evolution of void geometry is generally consistent with the qualitative findings of previous studies.The photogrammetric measurements yield comparable accuracy to laser scanning,with maximum errors of 13.2%for aperture and 14.4%for void volume.Most joint matching coefficient(JMC)measurement errors are below 20%.Larger measurement errors occur primarily in highly mismatched rock joints with JMC values below 0.2,but even in cases where measurement errors exceed 80%,the maximum JMC error is only 0.0434.Thus,the proposed photogrammetric approach holds promise for widespread application in void geometry measurements in rock joints.

Molecular Dynamics Simulation of Shock Response of CL-20 Co-crystals Containing Void Defects

To investigate the effect of void defects on the shock response of hexanitrohexaazaisowurtzitane(CL-20)co-crystals,shock responses of CL-20 co-crystals with energetic materials ligands trinitrotoluene(TNT),1,3-dinitrobenzene(DNB),solvents ligands dimethyl carbonate(DMC) and gamma-butyrolactone(GBL)with void were simulated,using molecular dynamics method and reactive force field.It is found that the CL-20 co-crystals with void defects will form hot spots when impacted,significantly affecting the decomposition of molecules around the void.The degree of molecular fragmentation is relatively low under the reflection velocity of 2 km/s,and the main reactions are the formation of dimer and the shedding of nitro groups.The existence of voids reduces the safety of CL-20 co-crystals,which induced the sensitivity of energetic co-crystals CL-20/TNT and CL-20/DNB to increase more significantly.Detonation has occurred under the reflection velocity of 4 km/s,energetic co-crystals are easier to polymerize than solvent co-crystals,and are not obviously affected by voids.The results show that the energy of the wave decreases after sweeping over the void,which reduces the chemical reaction frequency downstream of the void and affects the detonation performance,especially the solvent co-crystals.

Erosion Wear Behaviour of Kenaf/Glass Hybrid Polymer Composites

The awareness amongst the researchers to develop an environment friendly sustainable material leads to explore new class of plant-based fiber for making composites. Hybridization of such plant-based fiber with inclusion of engineered fiber is one of the promising methods to not only enhanced the mechanical performance but also suppressed the drawbacks that associate with such plant-based fiber to some extent. A usual hand lay-up method was taken-up in this work to fabricate four layered of hybrid kenaf(K)/glass(G)polyester laminates with different stacking order such as KKKK,KGKG,KGGK,GKKG and GGGG. The erosive character of the laminates was examined under three distinct particle velocities(48m/s, 70m/s,82m/s)and four different impact angles(30°, 45°, 60°, 90°). All fabricated laminates exhibited a semiductile character at lower velocities(48m/s and70m/s)as peak wear rate was observed at45° impact angle. However,they showed a semi-brittle character at high velocity(82m/s)as maximum rate of erosion was noticed at60° impact angle. Again,the influence of stacking order of piles on erosion wear was also clearly noticed. Moreover,the semi-brittle/semi-ductile characterization was also evidenced in accordance to the range of erosion efficiencies. The micro-structures of worn surfaces were inspected thoroughly from the images of scanning electron microscope(SEM)to evident the mechanism of erosion.

Erosive Wear Study of PPLSF/Glass Fiber Reinforced Hybrid Laminates

This work is focused to examine the erosive performance of hybrid Palmyra palm leaf stalk fiber(PPLSF)/glass polyester laminate against solid particle bombardment.A hand lay-up method was adopted for the fabricating four piles of five distinct laminates with different stacking order glass and PPLSF layers.Amongst them,one group of pure PPLSF and pure E-glass laminates were fabricated.The hybrid laminates were exposed to high speed stream of solid sand particle at three distinct impact velocities(48,70 and 82 m/s)and four different angles of impingement(30°,45°,60°and 90°).The effect of particle velocity,angle of impingement and stacking order on both wear rate and efficiency were highlighted.The experimental assessment reveals a significant improvement in erosive wear resistance properties due to hybridization of PPLSF with E-glass.Again,the laminates with PPLSF layer as skin and glass as core layer exhibited better erosive wear resistance properties than other types of laminates.Further,a maximum value of erosion at lower velocity(48 m/s)is also noticed at 45°impingement angle.However,at high velocity of impact 70 m/s and 82 m/s,the maximum rate of erosion has been shifted from 45°impact angle to 60°impact angle.The alternation of this semi-ductile character to semi-brittle character is evidenced by analyzing the experimental data.Further to justify the mode of erosion,the eroded surface samples were inspected by scanning electron microscope(SEM).

Non-Uniform Pion Tetrahedron Aether and Electron Tetrahedron Model

We propose that the QCD vacuum pion tetrahedron condensate density vary in space and drops to extremely low values in the Kennan, Barger and Cowie (KBC) void in analogy to earth’s atmospheric density drop with elevation from earth. We propose a formula for the gravitation acceleration based on the non-uniform pion tetrahedron condensate. Gravity may be due to the underlying microscopic attraction between quarks and antiquarks, which are part of the vacuum pion tetrahedron condensate. We propose an electron tetrahedron model, where electrons are comprised of tetraquark tetrahedrons, and . The quarks determine the negative electron charge and the or quarks determine the electron two spin states. The electron tetrahedron may perform a high frequency quark exchange reactions with the pion tetrahedron condensate by tunneling through the condensation gap creating a delocalized electron cloud with a fixed spin. The pion tetrahedron may act as a QCD glue bonding electron pairs in atoms and molecules and protons to neutrons in the nuclei. Conservation of valence quarks and antiquarks is proposed.

Cosmic Bubbles

The present paper is inspired by the article “Ho’oleilana: An Individual Baryon Acoustic Oscillation?” published by R. B. Tully, C. Howlett, and D. Pomarède on Sep. 2023 [1]. They claim: Evidence is presented here for the discovery of a remarkably strong individual contribution to the baryon acoustic oscillation (BAO) signal at z = 0.068, an entity that is given the name Ho’oleilana. K. Dawson, co-spokesperson for Dark Energy Spectroscopic Instrument is more inclined to believe that this latest finding is something of a coincidence, a chance alignment that simply looks like a sphere with a radius around what you’d expect for a BAO [2]. In this paper, we provide a short summary of experimental observations of Boötes Void and Superclusters;discuss the main features of the developed Hypersphere World-Universe Model;introduce notions “Cosmic Voids” and “Cosmic Bubbles”;elaborate a mathematical framework for different types of Cosmic Bubbles (Hubble Spherical Bubble for the World, Disk Bubbles for Galaxies;Spherical Bubbles for Extrasolar Systems, Dark Matter (DM) Spherical Bubbles for Galaxies and Superclusters);make a conclusion that the Boötes is a DM Cosmic Bubble and suggest experiments, which confirm our conclusion.

HARP-SiCoNi工艺在量产环境下提升高台阶比浅沟道隔离填充能力的研究

阐述基于量产环境中“高台阶比”的“非标准V型”STI结构,使用传统的HARP和SiCoNi组合工艺研究该结构Void Free的填充方案,并测试HARP预沉积厚度和SiCoNi刻蚀量的工艺窗口,实现量产环境下“高台阶比”的“非标准V型”沟槽Void Free填充。

A national survey of lower urinary tract symptoms in Jordan

Objective To determine the prevalence of lower urinary tract symptoms(LUTS)and their severity population in Jordan.Methods This cross-sectional survey was conducted using a paper-based survey between August and September in 2019.The study was carried out in the health care centers or hospitals in three different regions of Jordan:North(Irbid and Jarash),Middle(Amman,Madaba,Salt,and Zarqa),and South(Karak and Aqaba).Results To estimate the prevalence of LUTS,two definitions were used,including the first definition(presence of any LUTS regardless of the degree of severity)and the second definition(presence of any LUTS that occurs half the time or more).According to the first definition,1038(89.9%)reported LUTS(male:47.3%,female:52.7%),while 763(66.1%)reported LUTS according to the second definition(male:45.6%,female:54.4%).According to the International Prostate Symptom Score characterization,73.9%had nocturia and 62.9%reported daytime increased frequency.Conclusion LUTS are highly prevalent among the Jordanian population,and more than half of them have nocturia or daytime increased frequency as most frequently reported symptoms.

Assessment of a two-surface plasticity model for hexagonal materials

A computationally efficient two-surface plasticity model is assessed against crystal plasticity. Focus is laid on the mechanical behavior of magnesium alloys in the presence of ductility-limiting defects, such as voids. The two surfaces separately account for slip and twinning such that the constitutive formulation captures the evolving plastic anisotropy and evolving tension-compression asymmetry. For model identification, a procedure is proposed whereby the initial guess is based on a combination of experimental data and computationally intensive polycrystal calculations from the literature. In drawing direct comparisons with crystal plasticity, of which the proposed model constitutes a heuristically derived reduced-order model, the available crystal plasticity simulations are grouped in two datasets. A calibration set contains minimal data for both pristine and porous material subjected to one loading path. Then the two-surface model is assessed against a broader set of crystal plasticity simulations for voided unit cells under various stress states and two loading orientations. The assessment also includes microstructure evolution(rate of growth of porosity and void distortion). The ability of the two-surface model to capture essential features of crystal plasticity is analyzed along with an evaluation of computational cost. The prospects of using the model in guiding the development of physically sound damage models in Mg alloys are put forth in the context of high-throughput simulations.

Distribution Properties of Internal Air Voids in Ultrathin Asphalt Friction Course

The distribution characteristics of air voids in ultrathin asphalt friction course(UAFC) samples with different gradations and compaction methods were statistically analyzed using X-ray computed tomography(CT) and image analysis techniques. Based on the results, compared with the AC-5 sample, the OGFC-5mixture has a higher air void ratio, a larger air void size and a greater number of air voids, with the distribution of internal air voids being more uniform and their shapes being more rounded. The two-parameter Weibull function was applied to fit the gradation of air voids. The fitting results is good, and the function parameters are sensitive to changes in both mineral gradation and compaction method. Moreover, two homogeneity indices were proposed to evaluate the compaction uniformity of UAFC samples. Compared with the Marshall method,the SGC method is more conducive to improve the compaction uniformity of UAFC samples. The compaction method significantly influences the air void distribution characteristics and compaction uniformity of AC-5sample, but has a less significant impact on OGFC-5 sample. The experimental results in the study provides a solid foundation for further explorations on the internal structure and mixture design of UAFC.

Automated X-ray Defect Inspection on Occluded BGA Balls Using Hybrid Algorithm

Automated X-ray defect inspection of occluded objects has been an essential topic in semiconductors,autonomous vehicles,and artificial intelligence devices.However,there are few solutions to segment occluded objects in the X-ray inspection efficiently.In particular,in the Ball Grid Array inspection of X-ray images,it is difficult to accurately segment the regions of occluded solder balls and detect defects inside solder balls.In this paper,we present a novel automatic inspection algorithm that segments solder balls,and detects defects fast and efficiently when solder balls are occluded.The proposed algorithm consists of two stages.In the first stage,the defective candidates or defects are determined through the following four steps:(i)image preprocessing such as noise removal,contrast enhancement,binarization,connected component,and morphology,(ii)limiting the inspec-tion area to the ball regions and determining if the ball regions are occluded,(iii)segmenting each ball region into one or more regions with similar gray values,and(iv)determining whether there are defects or defective candidates in the regions using a weighted sum of local threshold on local variance.If there are defective candidates,the determination of defects is finally made in the following stage.In the second stage,defects are detected using the automated inspection technique based on oblique computed tomography.The 3D precision inspection process is divided into four steps:(i)obtaining 360 projection images(one image per degree)rotating the object from 0 to 360 degrees,(ii)reconstructing a 3D image from the 360 projected images,(iii)finding the center slice of gravity for solder balls from the axial slice images in the z-direction,and getting the inspection intervals between the upper bound and the lower bound from the center slice,and(iv)finally determining whether there are defects in the averaged image of solder balls.The proposed hybrid algorithm is robust for segmenting the defects inside occluded solder balls,and improves the performance of solder ball segmentation and defect detection algorithm.Experimental results show an accuracy of more than 97%.

Factors Influencing the Thermal Conductivity of Silt in the Yellow River Delta

The thermal conductivity of marine sediments is an important thermophysical parameter in the study of seafloor heat flow and marine engineering construction.Understanding the effect of thermal conductivity of marine sediments in the environment has a major engineering value and theoretical significance.In this work,a modified test method was used to measure the thermal conductivity of silt in the Yellow River Delta under different void ratios,moisture contents,temperatures,and salinities.Results showed that the thermal conductivity of silt in the Yellow River Delta decreased with the increase in the void ratio and increased with the water content.Compared with sand and clay,silt in the Yellow River Delta was the least affected by the void ratio and moisture content.Under low temperatures,the heat transfer of soil was controlled by the average velocity of the phonons;therefore,the thermal conductivity of silt in the Yellow River Estuary increased with temperature.The thermal conductivity of pore water decreased with increasing salinity.Moreover,certain salinity levels resulted in a phenomenon known as the‘compressing twin electrical layer’,which led to an increase in the contact area between soil particles.With the increase in salinity,the thermal conductivity of silt in the Yellow River Delta experiences an initial decline and a subsequent increase.The proposed thermal conductivity test method is more accurate than the existing technique,and the findings provide a basis for further study on the thermal characteristics of submarine sediments.

Characterizations of gas-liquid interface distribution and slug evolution in a vertical pipe

Large vertical pipes are key structures connecting subsea wells to offshore platforms.However,existing studies mainly focus on small vertical pipes.In a vertical acrylic pipe with 80 mm inner diameter and 11 m height,a high-speed camera was used to visually research the influences of pipe diameters,liquid properties and inlet effect on air-water co-flow characteristic.Different flow regime maps of vertical pipes(diameters are in the range of 50e189 mm)were compared and the critical gas velocity of the transition boundary from bubble to slug flow tended to increase with the increase of diameters at D≥80 mm.Drift-flux models were established in different flow regimes and liquid properties have a significant effect on drift coefficients of bubble flow and slug flow(void fraction a≤0.4).The influence of inlet turbulent effect on the gas-liquid interface distribution gradually weakened and disappeared from the pipe base to 85D,where the flow was fully developed.Slug frequency has a trend of increase first and then decrease with the gas Weber numbers increasing at low liquid superficial velocities(J_(L)≤0.31 m/s).And on the basis of this law,a new slug frequency correlation was proposed.It was found that there was an exponential relationship between the ratio of lengths of Taylor bubble to slug and the void fraction.