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Off-label-use of sulfur-hexafluoride in voiding urosonography for diagnosis of vesicoureteral reflux in children:A survey on adverse events 被引量:1
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作者 Alexander Sauer Clemens Wirth +7 位作者 Isabel Platzer Henning Neubauer Simon Veldhoen Alexander Dierks Reinhard Kaiser Andreas Kunz Meinrad Beer Thorsten Bley 《World Journal of Clinical Pediatrics》 2017年第1期52-59,共8页
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 contra... 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%. 展开更多
关键词 voiding urosonography Ultrasound contrast agent Vesicoureteral reflux SonoV ue Adverse events Sulfur hexafluoride
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Comparative study of conventional urosonography without contrast enhancement and x-ray voiding cystourethrography for diagnosis of vesicoureteral reflux in children 被引量:1
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作者 Nadide Basak Gulleroglu Kaan Gulleroglu Esra Baskin 《Discussion of Clinical Cases》 2020年第4期9-14,共6页
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... 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. 展开更多
关键词 Vesicoureteral reflux Conventional urosonography X-ray voiding cystourethrography Ureterovesical junction insertion angle
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Uncommon cause of voiding dysfunction in a female patient-vaginal abscess: A case report
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作者 Chia-Chi Yeh Stephen Shei-Dei Yang +1 位作者 Su-Cheng Huang Yi-Chun Wang 《World Journal of Clinical Cases》 SCIE 2018年第16期1199-1201,共3页
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 dysfuncti... 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. 展开更多
关键词 VAGINAL ABSCESS voiding DYSFUNCTION FEMALE Case report
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A Feasibility Study of an Individualized Voiding Program in Japan to Improve the Sense of Control in Older People with Functional Urinary Incontinence
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作者 Satsuki Nakamura Masakazu Kubota +1 位作者 Chiharu Akazawa Keiko Suyama 《Health》 2021年第3期253-272,共20页
<strong>Purpose: </strong>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 uri... <strong>Purpose: </strong>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. <strong>Method:</strong> 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. <strong>Results:</strong> 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. <strong>Conclusion: </strong>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. 展开更多
关键词 Individualized voiding Program Functional Urinary Incontinence Sense of Control Facility for Older People
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Botulinum Toxin-A for the Treatment of Voiding Dysfunction: Our Initial Experience
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作者 Sinharib Citgez Bulent Onal +4 位作者 Fetullah Gevher Cagatay Dogan Omer Kurt Oktay Demirkesen Bulent Cetinel 《Open Journal of Urology》 2012年第2期67-71,共5页
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 w... 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. 展开更多
关键词 BOTULINUM Toksin-A OVERACTIVE BLADDER voiding DYSFUNCTION
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Experimental Instrumentation for Measurement of Reactivity Temperature and Voiding Effects at Zero Power Research Reactors
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作者 Tomas Bily Lubomir Sklenka 《Journal of Energy and Power Engineering》 2013年第12期2396-2403,共8页
The paper describes the instrumentation for studying temperature and void reactivity effects that were developed at VR-I zero power reactor. Further are described its operational parameters, fields and ways of its uti... The paper describes the instrumentation for studying temperature and void reactivity effects that were developed at VR-I zero power reactor. Further are described its operational parameters, fields and ways of its utilization as well as issues connected to its implementation into the reactor core. 展开更多
关键词 Temperature reactivity effect void reactivity effect zero power reactor reactor experiments VR-1 reactor.
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Professor Wei-bin GAO's experience in treatment of voiding dysfunction with electroacupuncture
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作者 Shao-peng LIU Ming-yuan HAN +5 位作者 Xin-yuan CAO Ying-ying ZHU Jian-tao YIN Zhong-ren SUN Wei-bin GAO Hong-na YIN 《World Journal of Acupuncture-Moxibustion》 CAS CSCD 2024年第4期325-331,共7页
As a common clinical syndrome,voiding dysfunction is complicated in etiology,involved in a variety of diseases and associated with multi-disciplines of medicine.Either medication or surgery has not obtained the favora... As a common clinical syndrome,voiding dysfunction is complicated in etiology,involved in a variety of diseases and associated with multi-disciplines of medicine.Either medication or surgery has not obtained the favorable effect on it.Integrated the theories of traditional Chinese medicine and Western medicine and based on the pathogenesis of the disease,the acupoint specificity and neuromodulatory effects,Professor Wei-bin GAO suggested"selecting the acupoints along the affected areas"The acupoints located near to the lumbar,sacral and abdominal regions are dominated and stimulated with electroacupuncture at different electric waves.In treatment,electric stimulation with disperse and dense waves was adopted.The bone conduction theory of dense-wave electric field was proposed.The same neuromodulation is presented in different diseases such as neurogenic bladder,pediatric enuresis,senile nocturia,benign prostatic hyerplasia,and postpartum of postoperative urination disorders.Hence,the same therapeutic method is adoptable to different diseases with the basic acupoint composition modified. 展开更多
关键词 ELECTROACUPUNCTURE voiding dysfunction Wei-bin GAO EXPERIENCE
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Urodynamic analysis and treatment of male Parkinson's disease patients with voiding dysfunction 被引量:2
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作者 Xue Peng Wang Tao Zong Huantao Zhang Yong 《Chinese Medical Journal》 SCIE CAS CSCD 2014年第5期878-881,共4页
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 si... 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. 展开更多
关键词 Parkinson's disease voiding dysfunction URODYNAMICS
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Work Capacity of the Bladder During Voiding: A Novel Method to Evaluate Bladder Contractile Function and Bladder Outlet Obstruction 被引量:1
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作者 Ning Liu Li-Bo Man Feng He Guang-Lin Huang Ning Zhou Xiao-Fei Zhu 《Chinese Medical Journal》 SCIE CAS CSCD 2015年第24期3329-3334,共6页
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 it... 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. 展开更多
关键词 Bladder Function Bladder Outlet Obstruction URODYNAMICS Work in voiding
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A photogrammetric approach for quantifying the evolution of rock joint void geometry under varying contact states
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作者 Rui Yong Changshuo Wang +1 位作者 Nick Barton Shigui Du 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2024年第4期461-477,共17页
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 o... 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. 展开更多
关键词 Rock joint Void geometry evolution PHOTOGRAMMETRY APERTURE Void volume Joint matching coefficient
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Molecular Dynamics Simulation of Shock Response of CL-20 Co-crystals Containing Void Defects
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作者 Changlin Li Wei Yang +5 位作者 Qiang Gan Yajun Wang Lin Liang Wenbo Zhang Shuangfei Zhu Changgen Feng 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第1期364-374,共11页
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-dinitro... 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. 展开更多
关键词 CL-20 co-crystals Molecular dynamics simulation Reactive forcefield Impact response Hot spot Void defect
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A unified fractional flow framework for predicting the liquid holdup in two-phase pipe flows
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作者 Fuqiao Bai Yingda Lu Mukul M.Sharma 《Petroleum Science》 SCIE EI CAS CSCD 2024年第4期2614-2624,共11页
Two-phase pipe flow occurs frequently in oil&gas industry,nuclear power plants,and CCUS.Reliable calculations of gas void fraction(or liquid holdup)play a central role in two-phase pipe flow models.In this paper w... Two-phase pipe flow occurs frequently in oil&gas industry,nuclear power plants,and CCUS.Reliable calculations of gas void fraction(or liquid holdup)play a central role in two-phase pipe flow models.In this paper we apply the fractional flow theory to multiphase flow in pipes and present a unified modeling framework for predicting the fluid phase volume fractions over a broad range of pipe flow conditions.Compared to existing methods and correlations,this new framework provides a simple,approximate,and efficient way to estimate the phase volume fraction in two-phase pipe flow without invoking flow patterns.Notably,existing correlations for estimating phase volume fraction can be transformed and expressed under this modeling framework.Different fractional flow models are applicable to different flow conditions,and they demonstrate good agreement against experimental data within 5%errors when compared with an experimental database comprising of 2754 data groups from 14literature sources,covering various pipe geometries,flow patterns,fluid properties and flow inclinations.The gas void fraction predicted by the framework developed in this work can be used as inputs to reliably model the hydraulic and thermal behaviors of two-phase pipe flows. 展开更多
关键词 Pipe fractional flow Liquid holdup Multiphase pipe flow Gas void fraction
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A Novel Model for the Prediction of Liquid Film Thickness Distribution in Pipe Gas-Liquid Flows
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作者 Yubo Wang Yanan Yu +1 位作者 Qiming Wang Anxun Liu 《Fluid Dynamics & Materials Processing》 EI 2024年第9期1993-2006,共14页
A model is proposed for liquid film profile prediction in gas-liquid two-phase flow,which is able to provide the film thickness along the circumferential direction and the pressure gradient in the flow direction.A two... A model is proposed for liquid film profile prediction in gas-liquid two-phase flow,which is able to provide the film thickness along the circumferential direction and the pressure gradient in the flow direction.A two-fluid model is used to calculate both gas and liquid phases’flow characteristics.The secondary flow occurring in the gas phase is taken into account and a sailing boat mechanism is introduced.Moreover,energy conservation is applied for obtaining the liquid film thickness distribution along the circumference.Liquid film thickness distribution is calculated accordingly for different cases;its values are compared with other models and available experimental data.As a result,the newly proposed model is tested and good performances are demonstrated.The liquid film thickness distribution in small pipes and inclined pipes is also studied,and regime transition is revealed by liquid film profile evolution.The observed inflection point demonstrates that the liquid film thickness decreases steeply along the circumference,when the circle angle ranges between 30°and 50°for gas-liquid stratified flow with small superficial velocities. 展开更多
关键词 Film thickness secondary flow void fraction pressure gradient regime transition
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A Novel Method for Determining the Void Fraction in Gas-Liquid Multi-Phase Systems Using a Dynamic Conductivity Probe
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作者 Xiaochu Luo Xiaobing Qi +3 位作者 Zhao Luo Zhonghao Li Ruiquan Liao Xingkai Zhang 《Fluid Dynamics & Materials Processing》 EI 2024年第6期1233-1249,共17页
Conventional conductivity methods for measuring the void fraction in gas-liquid multiphase systems are typically affected by accuracy problems due to the presence of fluid flow and salinity.This study presents a novel... Conventional conductivity methods for measuring the void fraction in gas-liquid multiphase systems are typically affected by accuracy problems due to the presence of fluid flow and salinity.This study presents a novel approach for determining the void fraction based on a reciprocating dynamic conductivity probe used to measure the liquid film thickness under forced annular-flow conditions.The measurement system comprises a cyclone,a conductivity probe,a probe reciprocating device,and a data acquisition and processing system.This method ensures that the flow pattern is adjusted to a forced annular flow,thereby minimizing the influence of complex and variable gas-liquid flow patterns on the measurement results;Moreover,it determines the liquid film thickness solely according to circuit connectivity rather than specific conductivity values,thereby mitigating the impact of salinity.The reliability of the measurement system is demonstrated through laboratory experiments.The experimental results indicate that,in a range of gas phase superficial velocities 5–20 m/s and liquid phase superficial velocities 0.079–0.48 m/s,the maximum measurement deviation for the void fraction is 4.23%. 展开更多
关键词 Forced annular flow dynamic conductivity probe void fraction gas-liquid flow liquid film thickness
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Mechanism of cross-level settlements and void accumulation of wide and conventional sleepers in railway ballast
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作者 Olga Nabochenko Mykola Sysyn +1 位作者 Norman Krumnow Szabolcs Fischer 《Railway Engineering Science》 EI 2024年第3期361-383,共23页
The cross-level and twist irregularities are the most dangerous irregularity types that could cause wheel unloading with the risk of derailments and additional maintenance expenses.However,the mechanism of the irregul... The cross-level and twist irregularities are the most dangerous irregularity types that could cause wheel unloading with the risk of derailments and additional maintenance expenses.However,the mechanism of the irregularities initiation and development is unclear.The motivation of the present study was the previous experimental studies on the application of wide sleepers in the ballasted track.The long-term track geometry measurements with wide sleepers show an enormous reduction of the vertical longitudinal irregularities compared to the conventional track.However,wide sleepers had higher twist and cross-section level irregularities.The present paper aims to explain the phenomenon by discrete element method(DEM)modeling the development process of sleeper inhomogeneous support at cross-level depending on the sleeper form.The DEM simulations show that the maximal settlement intensity is up to 3.5 times lower for a wide sleeper in comparison with the conventional one.Nevertheless,the cross-level differential settlements are almost the same for both sleepers.The particle loading distribution after all loading cycles is concentrated on the smaller area,up to the half sleeper length,with fully unloaded zones under sleeper ends.Ballast flow limitation under the central part of the sleeper could improve the resilience of wide sleepers to the development of cross-level irregularities.The mechanism of initiation of the cross-level irregularity is proposed,which assumes the loss of sleeper support under sleeper ends.The further growth of inhomogeneous settlements along the sleeper is assumed as a result of the interaction of two processes:ballast flow due to dynamic impact during void closing and on the other side high pressure due to the concentration of the pressure under the middle part of the sleeper.The DEM simulation results support the assumption of the mechanism and agree with the experimental studies. 展开更多
关键词 Wide sleeper Ballasted track Sleeper support inhomogeneity Sleeper foot form Discrete element modeling Void accumulation
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Effect of perforation density distribution on production of perforated horizontal wellbore
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作者 KAREEM Hasanain J. HASINI Hasril ABDULWAHID Mohammed A. 《Petroleum Exploration and Development》 SCIE 2024年第2期464-475,共12页
To address the issue of horizontal well production affected by the distribution of perforation density in the wellbore,a numerical model for simulating two-phase flow in a horizontal well is established under two perf... To address the issue of horizontal well production affected by the distribution of perforation density in the wellbore,a numerical model for simulating two-phase flow in a horizontal well is established under two perforation density distribution conditions(i.e.increasing the perforation density at inlet and outlet sections respectively).The simulation results are compared with experimental results to verify the reliability of the numerical simulation method.The behaviors of the total pressure drop,superficial velocity of air-water two-phase flow,void fraction,liquid film thickness,air production and liquid production that occur with various flow patterns are investigated under two perforation density distribution conditions based on the numerical model.The total pressure drop,superficial velocity of the mixture and void fraction increase with the air flow rate when the water flow rate is constant.The liquid film thickness decreases when the air flow rate increases.The liquid and air productions increase when the perforation density increases at the inlet section compared with increasing the perforation density at the outlet section of the perforated horizontal wellbore.It is noted that the air production increases with the air flow rate.Liquid production increases with the bubble flow and begins to decrease at the transition point of the slug-stratified flow,then increases through the stratified wave flow.The normalized liquid flux is higher when the perforation density increases at the inlet section,and increases with the radial air flow rate. 展开更多
关键词 horizontal wellbore two-phase flow pattern perforation density wellbore pressure drop void fraction production performance
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Erosion Wear Behaviour of Kenaf/Glass Hybrid Polymer Composites
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作者 Chandrakanta Mishra Deepak Kumar Mohapatra +2 位作者 Chitta Ranjan Deo Punyapriya Mishra Kiran Kumar Ekka 《Journal of Harbin Institute of Technology(New Series)》 CAS 2024年第1期78-89,共12页
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 inclusi... 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. 展开更多
关键词 hybrid composites erosion wear VOID micro⁃hardness
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Erosive Wear Study of PPLSF/Glass Fiber Reinforced Hybrid Laminates
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作者 Chetana Tripathy Deepak Kumar Mohapatra +1 位作者 Chitta Ranjan Deo Punyapriya Mishra 《Journal of Harbin Institute of Technology(New Series)》 CAS 2024年第2期68-79,共12页
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 f... 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). 展开更多
关键词 hybrid composites erosion wear VOID micro-hardness SEM
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Non-Uniform Pion Tetrahedron Aether and Electron Tetrahedron Model
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作者 Rami Rom 《Journal of High Energy Physics, Gravitation and Cosmology》 CAS 2024年第2期810-824,共15页
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 elevat... 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. 展开更多
关键词 Standard Model (SM) QCD Vacuum Condensate Electric Dipole Moment (EDM) KBC Void ANTIMATTER MOND Theory Aether
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Cosmic Bubbles
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作者 Vladimir S. Netchitailo 《Journal of High Energy Physics, Gravitation and Cosmology》 CAS 2024年第1期438-453,共16页
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 ... 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. 展开更多
关键词 World-Universe Model Boötes Void Boötes Superclusters Macroobjects Bubbles Dark Matter Bubbles Fermi Bubbles Boötes Bubbles
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