Flow Regimes in Bubble Columns with and without Internals: A Review

Hydrodynamics characterization in terms offlow regime behavior is a crucial task to enhance the design of bubble column reactors and scaling up related methodologies.This review presents recent studies on the typicalflow regimes established in bubble columns.Some effort is also provided to introduce relevant definitions pertaining to thisfield,namely,that of“void fraction”and related(local,chordal,cross-sectional and volumetric)variants.Experimental studies involving different parameters that affect design and operating conditions are also discussed in detail.In the second part of the review,the attention is shifted to cases with internals of various types(perfo-rated plates,baffles,vibrating helical springs,mixers,and heat exchanger tubes)immersed in the bubble columns.It is shown that the presence of these elements has a limited influence on the global column hydrodynamics.However,they can make the homogeneousflow regime more stable in terms of transition gas velocity and transi-tion holdup value.The last section is used to highlight gaps which have not beenfilled yet and future directions of investigation.

Mechanism of internal thermal runaway propagation in blade batteries

Blade batteries are extensively used in electric vehicles,but unavoidable thermal runaway is an inherent threat to their safe use.This study experimentally investigated the mechanism underlying thermal runaway propagation within a blade battery by using a nail to trigger thermal runaway and thermocouples to track its propagation inside a cell.The results showed that the internal thermal runaway could propagate for up to 272 s,which is comparable to that of a traditional battery module.The velocity of the thermal runaway propagation fluctuated between 1 and 8 mm s^(-1),depending on both the electrolyte content and high-temperature gas diffusion.In the early stages of thermal runaway,the electrolyte participated in the reaction,which intensified the thermal runaway and accelerated its propagation.As the battery temperature increased,the electrolyte evaporated,which attenuated the acceleration effect.Gas diffusion affected thermal runaway propagation through both heat transfer and mass transfer.The experimental results indicated that gas diffusion accelerated the velocity of thermal runaway propagation by 36.84%.We used a 1D mathematical model and confirmed that convective heat transfer induced by gas diffusion increased the velocity of thermal runaway propagation by 5.46%-17.06%.Finally,the temperature rate curve was analyzed,and a three-stage mechanism for internal thermal runaway propagation was proposed.In Stage I,convective heat transfer from electrolyte evaporation locally increased the temperature to 100℃.In Stage II,solid heat transfer locally increases the temperature to trigger thermal runaway.In StageⅢ,thermal runaway sharply increases the local temperature.The proposed mechanism sheds light on the internal thermal runaway propagation of blade batteries and offers valuable insights into safety considerations for future design.

Seeing beneath the surface:Harnessing point-of-care ultrasound for internal jugular vein evaluation

Point-of-care ultrasound(POCUS)of the internal jugular vein(IJV)offers a noninvasive means of estimating right atrial pressure(RAP),especially in cases where the inferior vena cava is inaccessible or unreliable due to conditions such as liver disease or abdominal surgery.While many clinicians are familiar with visually assessing jugular venous pressure through the internal jugular vein,this method lacks sensitivity.The utilization of POCUS significantly enhances the visualization of the vein,leading to a more accurate identification.It has been demonstrated that combining IJV POCUS with physical examination enhances the specificity of RAP estimation.This review aims to provide a comprehensive summary of the various sonographic techniques available for estimating RAP from the internal jugular vein,drawing upon existing data.

Relative Impacts of Sea Ice Loss and Atmospheric Internal Variability on the Winter Arctic to East Asian Surface Air Temperature Based on Large-Ensemble Simulations with NorESM2

To quantify the relative contributions of Arctic sea ice and unforced atmospheric internal variability to the “warm Arctic, cold East Asia”(WACE) teleconnection, this study analyses three sets of large-ensemble simulations carried out by the Norwegian Earth System Model with a coupled atmosphere–land surface model, forced by seasonal sea ice conditions from preindustrial, present-day, and future periods. Each ensemble member within the same set uses the same forcing but with small perturbations to the atmospheric initial state. Hence, the difference between the present-day(or future) ensemble mean and the preindustrial ensemble mean provides the ice-loss-induced response, while the difference of the individual members within the present-day(or future) set is the effect of atmospheric internal variability. Results indicate that both present-day and future sea ice loss can force a negative phase of the Arctic Oscillation with a WACE pattern in winter. The magnitude of ice-induced Arctic warming is over four(ten) times larger than the ice-induced East Asian cooling in the present-day(future) experiment;the latter having a magnitude that is about 30% of the observed cooling. Sea ice loss contributes about 60%(80%) to the Arctic winter warming in the present-day(future) experiment. Atmospheric internal variability can also induce a WACE pattern with comparable magnitudes between the Arctic and East Asia. Ice-lossinduced East Asian cooling can easily be masked by atmospheric internal variability effects because random atmospheric internal variability may induce a larger magnitude warming. The observed WACE pattern occurs as a result of both Arctic sea ice loss and atmospheric internal variability, with the former dominating Arctic warming and the latter dominating East Asian cooling.

Correction to:Error Calculation of Large-Amplitude Internal Solitary Waves Within the Pycnocline Introduced by the Strong Stratification Approximation

In the original publication the third author name is published incorrectly as“Hayatdavoodi Masoud”.The correct author name should be read as“Masoud Hayatdavoodi”.The correct author name is available in this correction.

Equivalence between the internal observability and equation

This paper is concerned with a third order in time linear Moore-Gibson-Thompson equation which describes the acoustic velocity potential in ultrasound wave program.Influenced by the work of Kaltenbacher,Lasiecka and Marchand(Control Cybernet.2011,40:971-988),we establish an observability inequality of the conservative problem,and then discuss the equivalence between the exponential stabilization of a dissipative system and the internal observational inequality of the corresponding conservative system.

Observation of Doppler shift f_(D) modulated by the internal kink mode using conventional reflectometry in the EAST tokamak

In this paper we present a new experimental observation using a conventional reflectometry technique,poloidal correlation reflectometry(PCR),in the Experimental Advanced Superconducting Tokamak(EAST).The turbulence spectrum detected by the PCR system exhibits an asymmetry and induced Doppler shift f_(D)during the internal kink mode(IKM)rotation phase.This Doppler shift f_(D)is the target measurement of Doppler reflectometry,but captured by conventional reflectometry.Results show that the Doppler shift f_(D)is modulated by the periodic changes in the effective angle between the probing wave and cutoff layer normal,but not by plasma turbulence.The fishbone mode and saturated long-lived mode are typical IKMs,and this modulation phenomenon is observed in both cases.Moreover,the value of the Doppler shift f_(D)is positively correlated with the amplitude of the IKM,even when the latter is small.However,the positive and negative frequency components of the Doppler shift f_(D)can be asymmetric,which is related to the plasma configuration.A simulated analysis is performed by ray tracing to verify these observations.These results establish a clear link between f_(D)and IKM rotation,and are helpful for studying the characteristics of IKM and related physical phenomena.

Data-driven modeling on anisotropic mechanical behavior of brain tissue with internal pressure

Brain tissue is one of the softest parts of the human body,composed of white matter and grey matter.The mechanical behavior of the brain tissue plays an essential role in regulating brain morphology and brain function.Besides,traumatic brain injury(TBI)and various brain diseases are also greatly influenced by the brain's mechanical properties.Whether white matter or grey matter,brain tissue contains multiscale structures composed of neurons,glial cells,fibers,blood vessels,etc.,each with different mechanical properties.As such,brain tissue exhibits complex mechanical behavior,usually with strong nonlinearity,heterogeneity,and directional dependence.Building a constitutive law for multiscale brain tissue using traditional function-based approaches can be very challenging.Instead,this paper proposes a data-driven approach to establish the desired mechanical model of brain tissue.We focus on blood vessels with internal pressure embedded in a white or grey matter matrix material to demonstrate our approach.The matrix is described by an isotropic or anisotropic nonlinear elastic model.A representative unit cell(RUC)with blood vessels is built,which is used to generate the stress-strain data under different internal blood pressure and various proportional displacement loading paths.The generated stress-strain data is then used to train a mechanical law using artificial neural networks to predict the macroscopic mechanical response of brain tissue under different internal pressures.Finally,the trained material model is implemented into finite element software to predict the mechanical behavior of a whole brain under intracranial pressure and distributed body forces.Compared with a direct numerical simulation that employs a reference material model,our proposed approach greatly reduces the computational cost and improves modeling efficiency.The predictions made by our trained model demonstrate sufficient accuracy.Specifically,we find that the level of internal blood pressure can greatly influence stress distribution and determine the possible related damage behaviors.

Alkali Tolerance of Concrete Internal Curing Agent Based on Sodium Carboxymethyl Starch

Internal curing agents (ICA) based on super absorbent polymer have poor alkali tolerance and reduce the early strength of concrete.An alkali tolerate internal curing agent (CAA-ICA) was designed and prepared by using sodium carboxymethyl starch (CMS) with high hydrophilicity,acrylic acid (AA) containing anionic carboxylic group and acrylamide (AM) containing non-ionic amide group as the main raw materials.The results show that the ratio of CAA-ICA alkali absorption solution is higher than that existing ICA,which solves the low water absorption ratio of the ICA in alkali environment.The water absorption ratio of CAA-ICA in saturated Ca(OH)_(2) solution is 95.8 g·g^(-1),and the alkali tolerance coefficient is 3.4.The application of CAA-ICA in cement-based materials can increase the internal relative humidity and miniaturize the pore structure.The compressive strength of mortar increases up to 12.95%at 28 d,which provids a solution to overcome the reduction of the early strength.

Investigation of risk factors in the development of recurrent urethral stricture after internal urethrotomy

BACKGROUND Urethral stricture is a condition that often develops with trauma and results in narrowing of the urethral lumen.Although endoscopic methods are mostly used in its treatment,it has high recurrence rates.Therefore,open urethroplasty is recommended after unsuccessful endoscopic treatments.AIM To investigate the risk factors associated with urethral stricture recurrence.METHODS The data of male patients who underwent internal urethrotomy for urethral stricture between January 2017 and January 2023 were retrospectively analyzed.Demographic data,comorbidities,preoperative haemogram,and biochemical values obtained from peripheral blood and operative data were recorded.Patients were divided into two groups in terms of recurrence development;recurrence and non-recurrence.Initially recorded data were compared between the two groups.RESULTS A total of 303 patients were included in the study.The mean age of the patients was 66.6±13.6 years.The mean duration of recurrence development was 9.63±9.84(min-max:1-39)months in the recurrence group.Recurrence did not occur in non-recurrence group throughout the follow-up period with an average time of 44.15±24.07(min-max:12-84)months.In the comparison of both groups,the presence of diabetes mellitus(DM),hypertension(HT),and multiple comorbidi-ties were significantly higher in the recurrence(+)group(P=0.038,P=0.012,P=0.013).Blood group,postoperative use of non-steroidal anti-inflammatory drugs,preoperative cystostomy,cause of stricture,iatrogenic cause of stricture,location and length of stricture,indwelling urinary cathater size and day of catheter removal did not differ between the two groups.No statistically significant difference was observed between the two groups in terms of age,uroflowmetric maximum flow rate value,hemo-gram parameters,aspartate aminotransferase(AST),alanine aminotransferase(ALT),fasting blood sugar,creati-nine,glomerular filtration rate,neutrophil-lymphocyte ratio,platelet-lymphocyte ratio,lymphocyte-monocyte ratio,monocyte-lymphocyte ratio and AST/ALT ratios.CONCLUSION In patients with urethral stricture recurrence,only the frequency of DM and HT was high,while inflammation marker levels and stricture-related parameters were similar between the groups.

Intestinal Parasitosis in Children among Internally Displaced Persons in the Hauts-Bassins Region of Burkina Faso

Introduction: The setting up of camps for internally displaced persons in Burkina Faso as a result of terrorism creates favorable conditions for the emergence of digestive parasitosis in these displaced populations. The objective of this study was to evaluate the prevalence of digestive parasitosis in children of this population in the Hauts-Bassins region. Material and methods: This was a prospective cross-sectional study from November to December 2020, in which stool samples were collected from internally displaced children from the Sinfra reception site in Banzon and from Poya in Karangasso Vigué. The stool samples were stored at room temperature, protected from dust and insects, in a cooler and then sent to the laboratory of the CHUSS in Bobo-Dioulasso where the parasitological analyses were performed. Results: The mean age was 5.8 ± 2.4 years. The most represented age group was 5 to 10 years (75.31%). The sex ratio is 1.61. The overall prevalence of intestinal parasite infection was 53.09%. The prevalence was statistically higher among those who consumed well water than those consuming tap water (p = 0.01). Monoparasitism by protozoa and helminths represented 74.42% and 6.68% respectively. The polyparasitism rate was 9.31%. The species identified in monoparasite patients were protozoa with Entamoeba coli (37.21%), Giardia lamblia (25.58%), Endolimax nanus (6.98%) and Entamoeba histolytica/dispar (4.65%). Biparasitism was identified with combinations, such as E. coli + E. histolytica/dispar (11.63%). Conclusion: There is a high prevalence of digestive parasitosis among IDPs in the Sinfra and Poya reception site. Educational sessions on hand washing before meals, use of drinking water, etc. should emphasize preventive measures in these IDP camps.

Internal phase control of fiber laser array based on photodetector array

Coherent beam combining(CBC) of fiber laser array is a promising technique to realize high output power while maintaining near diffraction-limited beam quality. To implement CBC, an appropriate phase control feedback structure should be established to realize phase-locking. In this paper, an innovative internal active phase control CBC fiber laser array based on photodetector array is proposed. The dynamic phase noises of the laser amplifiers are compensated before being emitted into free space. And the static phase difference compensation of emitting laser array is realized by interference measurement based on photodetector array. The principle of the technique is illustrated and corresponding simulations are carried out, and a CBC system with four laser channels is built to verify the technique. When the phase controllers are turned on, the phase deviation of the laser array is less than λ/20, and ~ 95% fringe contrast of the irradiation distribution is obtained. The technique proposed in this paper could provide a reference for the system design of a massive high-power CBC system.

Multi-Stage Multidisciplinary Design Optimization Method for Enhancing Complete Artillery Internal Ballistic Firing Performance

To enhance the comprehensive performance of artillery internal ballistics—encompassing power,accuracy,and service life—this study proposed a multi-stage multidisciplinary design optimization(MS-MDO)method.First,the comprehensive artillery internal ballistic dynamics(AIBD)model,based on propellant combustion,rotation band engraving,projectile axial motion,and rifling wear models,was established and validated.This model was systematically decomposed into subsystems from a system engineering perspective.The study then detailed the MS-MDO methodology,which included Stage I(MDO stage)employing an improved collaborative optimization method for consistent design variables,and Stage II(Performance Optimization)focusing on the independent optimization of local design variables and performance metrics.The methodology was applied to the AIBD problem.Results demonstrated that the MS-MDO method in Stage I effectively reduced iteration and evaluation counts,thereby accelerating system-level convergence.Meanwhile,Stage II optimization markedly enhanced overall performance.These comprehensive evaluation results affirmed the effectiveness of the MS-MDO method.

Endoscopic polidocanol foam sclerobanding for the treatment of grade Ⅱ-Ⅲ internal hemorrhoids:A prospective,multi-center,randomized study

BACKGROUND Endoscopic rubber band ligation(ERBL)is a nonsurgical technique for the treatment of symptomatic internal hemorrhoids but is limited by recurrence and post-procedural pain.AIM To evaluate satisfaction,long-term recurrence,and post-procedural pain in managing internal hemorrhoids using a combination of polidocanol foam sclerotherapy and ERBL.METHODS This was a prospective,multicenter,randomized study.A total of 195 consecutive patients diagnosed with grade II-III internal hemorrhoids were enrolled from four tertiary hospitals and randomly divided into a cap-assisted endoscopic polidocanol foam sclerobanding(EFSB)or an ERBL group.All patients were followed-up for 12 months.Symptom-based severity and post-procedural pain were assessed using a hemorrhoid severity score(HSS)and a visual analog scale(VAS).Continuous variables were reported as medians and interquartile range.RESULTS One hundred and ninety-five patients were enrolled,with 98 in the EFSB group.HSS was lower in the EFSB group than in the ERBL group at 8 weeks[4.0(3.0-5.0)vs 5.0(4.0-6.0),P=0.003]and 12-month[2.0(1.0-3.0)vs 3.0(2.0-3.0),P<0.001]of follow-up.The prolapse recurrence rate was lower in the EFSB group at 12 months(11.2%vs 21.6%,P=0.038).Multiple linear regression analysis demonstrated that EFSB treatment[B=-0.915,95%confidence interval(CI):−1.301 to−0.530,P=0.001]and rubber band number(B=0.843,95%CI:0.595-1.092,P<0.001)were negatively and independently associated with the VAS score 24 hours post-procedure.The median VAS was lower in the EFSB group than in the ERBL[2.0(1.0-3.0)vs 3.0(2.0-4.0),P<0.001].CONCLUSION Cap-assisted EFSB provided long-term satisfaction and effective relief from the recurrence of prolapse and pain 24 hours post-procedure.

Experimental Study on the Variation of Optical Imaging Characteristics with Zenith Angle due to Internal Solitary Waves in Sunglint

Internal solitary waves(ISWs)change the roughness of the sea surface,thus producing dark and bright bands in optical images.However,reasons for changes in imaging characteristics with the solar zenith angle remain unclear.In this paper,the optical imaging pattern of ISWs in sunglint under different zenith angles of the light source is investigated by collecting optical images of ISWs through physical simulation.The experiment involves setting 10 zenith angles of the light source,which are divided into area a the optical images of ISWs in the three areas show dark-bright mode,single bright band,and bright-dark mode,which are consistent with those observed by optical remote sensing.In addition,this study analyzed the percentage of the dark and bright areas of the bands and the change in the relative gray difference and found changes in both areas under different zenith angles of the light source.The MODIS and ASAR images display a similar brightness-darkness distance of the same ISWs.Therefore,the relationship between the brightness-darkness distance and the characteristic half-width of ISWs is determined in accordance with the eKdV theory and the imaging mechanism of ISWs of the SAR image.Overall,the relationship between them in the experiment is almost consistent with the theoretical result.

Effect of internal structure of a batch-processing wet-etch reactor on fluid flow and heat transfer

Batch-processing wet-etch reactors are the key equipment widely used in chip fabrication,and their performance is largely affected by the internal structure.This work develops a three-dimensional computational fluid dynamics(CFD)model considering heat generation of wet-etching reactions to investigate the fluid flow and heat transfer in the wet-etch reactor.The backflow is observed below and above the wafer region,as the flow resistance in this region is high.The temperature on the upper part of a wafer is higher due to the accumulation of reaction heat,and the average temperature of the side wafer is highest as its convective heat transfer is weakest.Narrowing the gap between wafer and reactor wall can force the etchant to flow in the wafer region and then facilitate the convective heat transfer,leading to better within-wafer and wafer-to-wafer etch uniformities.An inlet angle of 60°balances fluid by-pass and mechanical energy loss,and it yields the best temperature and etch uniformities.The batch with 25wafers has much wider flow channels and much lower flow resistance compared with that with 50wafers,and thus it shows better temperature and etch uniformities.These results and the CFD model should serve to guide the optimal design of batch-processing wet-etch reactors.

An internal ballistic model of electromagnetic railgun based on PFN coupled with multi-physical field and experimental validation

To accelerate the practicality of electromagnetic railguns,it is necessary to use a combination of threedimensional numerical simulation and experiments to study the mechanism of bore damage.In this paper,a three-dimensional numerical model of the augmented railgun with four parallel unconventional rails is introduced to simulate the internal ballistic process and realize the multi-physics field coupling calculation of the rail gun,and a test experiment of a medium-caliber electromagnetic launcher powered by pulse formation network(PFN)is carried out.Various test methods such as spectrometer,fiber grating and high-speed camera are used to test several parameters such as muzzle initial velocity,transient magnetic field strength and stress-strain of rail.Combining the simulation results and experimental data,the damage condition of the contact surface is analyzed.

Interaction between internal solitary waves and the seafloor in the deep sea

Internal solitary wave(ISW),as a typical marine dynamic process in the deep sea,widely exists in oceans and marginal seas worldwide.The interaction between ISW and the seafloor mainly occurs in the bottom boundary layer.For the seabed boundary layer of the deep sea,ISW is the most important dynamic process.This study analyzed the current status,hotspots,and frontiers of research on the interaction between ISW and the seafloor by CiteSpace.Focusing on the action of ISW on the seabed,such as transformation and reaction,a large amount of research work and results were systematically analyzed and summarized.On this basis,this study analyzed the wave–wave interaction and interaction between ISW and the bedform or slope of the seabed,which provided a new perspective for an in‐depth understanding of the interaction between ISW and the seafloor.Finally,the latest research results of the bottom boundary layer and marine engineering stability by ISW were introduced,and the unresolved problems in the current research work were summarized.This study provides a valuable reference for further research on the hazards of ISW to marine engineering geology.

Misdiagnosed Meckel's diverticulum with internal hernia mimicking appendicitis:A case report

BACKGROUND Meckel's diverticulum is a common congenital anomaly of the gastrointestinal tract,with a higher incidence rate in children under 7 years old.The condition is characteristically asymptomatic but may become a clinical concern when complications such as intestinal obstruction,bleeding,perforation,or diverticulitis precipitate acute abdominal presentations.CASE SUMMARY This report describes the case of a middle-aged man initially suspected of having acute appendicitis,which rapidly progressed to acute peritonitis with concomitant intestinal obstruction observed during preoperative assessment.Surgical exploration confirmed the diagnosis of Meckel's diverticulum-induced internal hernia,accompanied by intestinal obstruction and necrosis.In addition,the hernial ring base exhibited entrapment resembling a surgical knot.CONCLUSION Meckel's diverticulum is a rare cause of small bowel obstruction in adults,and it should be considered in a differential diagnosis.

Internal limiting membrane peeling combined with silicone oil or air tamponade for highly myopic foveoschisis

AIM:To compare the efficacy of pars plana vitrectomy(PPV)combined with internal limiting membrane(ILM)and silicone oil or sterile air tamponade for the treatment of myopic foveoschisis(MF)in highly myopic eyes.METHODS:This retrospective study included 48 myopic eyes of 40 patients with MF and axial lengths(ALs)ranging from 26-32 mm treated between January 2020 and January 2022.All patients were underwent PPV combined with ILM peeling followed by sterile air or silicone oil tamponade and followed up at least 12mo.Based on the features on spectral-domain optical coherence tomography(SD-OCT),the eyes were divided into the MF-only group(Group A,n=15 eyes),MF with central foveal detachment group(Group B,n=20 eyes),and MF with lamellar macular hole group(Group C,n=13 eyes).According to AL,eyes were further divided into three groups:Group D(26.01-28.00 mm,n=12 eyes),Group E(28.01-30.00 mm,n=26 eyes),and Group F(30.01-32.00 mm,n=10 eyes).The best-corrected visual acuity(BCVA),central foveal thickness(CFT),and complications were recorded.RESULTS:The patients included 16 males and 24 females with the mean age of 56±9.82y.The BCVA and CFT improved in all groups after surgery(P<0.01),while there was no significant difference of the CFT in Group A,B,and C postoperatively(P>0.05).The intergroup differences of BCVA and CFT postoperatively were statistically significant in Group D,E,and F.Twenty eyes were injected with sterile air,and 28 eyes were injected with silicone oil for tamponade based on the AL.However,there was no statistically significant difference among Groups D,E,and F in terms of the results of sterile air or silicone oil tamponade.The mean recovery time was 5.9mo for MF patients subjected to silicone oil tamponade and 7.7mo for patients subjected to sterile air tamponade,and the difference was not statistically significant.CONCLUSION:PPV and ILM peeling combined with silicone oil or sterile air tamponade can achieve good results for MF in highly myopic eyes with ALs≤32 mm.