In recent years,tuned liquid dampers(TLDs)have attracted significant research interest;however,overall progress has been limited due to insufficient understanding of the mechanisms governing sloshing-induced loads.In ...In recent years,tuned liquid dampers(TLDs)have attracted significant research interest;however,overall progress has been limited due to insufficient understanding of the mechanisms governing sloshing-induced loads.In particular,it remains unclear whether the water in aqueducts—common water-diversion structures in many countries—can serve as an effective TLD.This study investigates the generation mechanisms of sloshing loads during the first-order transverse resonance of water in a U-shaped aqueduct using a two-dimensional(2D)numerical model.The results reveal that,at the equilibrium position,the free surface difference between the left and right walls,the horizontal force on the aqueduct,and the fluctuating component of the vertical force all reach their maxima,with energy predominantly stored as potential energy.At the maximum displacement position,the surface difference and horizontal force drop to zero,while the fluctuating vertical force attains its minimum and energy shifts primarily to kinetic form.At this stage,static pressure is governed solely by the vertical convective acceleration,whereas at equilibrium it is closely linked to both the free surface difference and vertical local acceleration of the water.This dynamic energy exchange generates vertical force oscillations even when the free surface appears nearly symmetric.展开更多
In recent years,tuned liquid dampers(TLDs)have emerged as a focal point of research due to their remarkable potential for structural vibration mitigation.Yet,progress in this field remains constrained by an incomplete...In recent years,tuned liquid dampers(TLDs)have emerged as a focal point of research due to their remarkable potential for structural vibration mitigation.Yet,progress in this field remains constrained by an incomplete understanding of the fundamental mechanisms governing sloshing-induced loads in liquid-filled containers.Aqueducts present a distinctive case,as the capacity of their contained water to function effectively as a TLD remains uncertain.To address this gap,the present study investigates the generation mechanisms of sloshing loads under non-resonant cases through a two-dimensional(2D)computational fluid dynamics(CFD)model developed in ANSYS Fluent.The incompressible Reynolds-Averaged Navier–Stokes(RANS)equations are solved,while the Volume of Fluid(VOF)method captures the evolution of the air–water interface.Turbulent flow behavior is modeled using the RNG-approach.The ensuing results reveal the dynamic characteristics of the horizontal force(fℎ)and the fluctuating component of the vertical force(Fof).Fh is predominantly governed by the inertia of the deep-water region and its phase varies coherently with the aqueduct’s acceleration.With increasing excitation amplitude(A)and frequency(f),the contribution of deep-water inertia to𝐹ℎintensifies markedly,accounting for 82.6–92.1%of the total horizontal load at an excitation amplitude of 0.15 m and frequencies of 1.0–1.6 Hz.The extreme values of Fof arise primarily from asymmetric static pressures induced by free-surface fluctuations,which are further amplified when wall gaps appear at large amplitudes(A≥10 cm)and high frequencies(f≥1.4 Hz).Unlike resonant cases dominated by free-surface resonance,non-resonant sloshing loads are principally driven by deep-water inertia and motion-induced surface asymmetry.展开更多
In this paper, a full-scale 3-D finite element model of the Jundushan cable-stayed aqueduct bridge is established with ANSYS Code. The shell, fluid, tension-only spar and beam elements are used for modeling the aquedu...In this paper, a full-scale 3-D finite element model of the Jundushan cable-stayed aqueduct bridge is established with ANSYS Code. The shell, fluid, tension-only spar and beam elements are used for modeling the aqueduct deck, filled water, cables and support towers, respectively. A multi-element cable formulation is introduced to simulate the cable vibration. The dry （without water） and wet （with water） modes of the aqueduct bridge are both extracted and investigated in detail. The dry modes of the aqueduct bridge are basically similar to those of highway cable-stayed bridges. A dry mode may correspond to two types of wet modes, which are called the in-phase （with lower frequency） and out-of-phase （with higher frequency） modes. When the water-structure system vibrates in the in-phase/out-of-phase modes, the aqueduct deck moves and water sloshes in the same/opposite phase-angle, and the sloshing water may take different surface-wave modes. The wet modes of the system reflect the properties of interaction among the deck, towers, cables and water. The in-phase wet frequency generally decreases as the water depth increases, and the out-of-phase wet frequency may increase or decrease as the water depth increases.展开更多
Enlarged vestibular aqueduct(EVA), the most frequent identifiable cause of congenital hearing loss, is evaluated with high-definition multidetector CT in the axial plane. Our purpose was to determine which reformatted...Enlarged vestibular aqueduct(EVA), the most frequent identifiable cause of congenital hearing loss, is evaluated with high-definition multidetector CT in the axial plane. Our purpose was to determine which reformatted CT measurements are most reproducible. Seven multiplanar reformatted images were created for each of the 64 temporal bones in patients with EVA. Intraclass correlation coefficients(ICC) were used to assess inter-observer variability, and both linear regression and ROC analyses were used to compare the measurements with severity of hearing loss, as assessed by pure tone audiometry. All seven measurements had excellent inter-observer variability, with average-measure ICC ranging from 0.92 to 0.98. There was no statistically significant correlation between the radiologic degree of aqueduct enlargement and severity of hearing loss using any of the seven measurements; ROC analyses revealed areas under the curves ranging from 0.57 to 0.73. Optimal accuracy was obtained with a threshold of 1.75 mm as measured at the aqueductal aperture in the P€oschl plane, with sensitivity of 0.75 and specificity of0.63. Although the radiologic measurement may not serve as a reliable tool for assessing severity of EVA, P€oschl plane reformatting has proven to be better than conventional axial acquisition plane for identifying patients with clinically significant hearing loss.展开更多
nPendred syndrome （PS） is characterized by autosomal recessive inheritance of goiter associated with a defect of iodide organification, hearing loss, enlargement of the vestibular aqueduct （EVA）, and mutations of ...nPendred syndrome （PS） is characterized by autosomal recessive inheritance of goiter associated with a defect of iodide organification, hearing loss, enlargement of the vestibular aqueduct （EVA）, and mutations of the SLC26A4 gene. However, not all EVA patients have PS or SLC26A4 mutations. Two mutant alleles of SLC26A4 are detected in 1/4 of North American or European EVA populations, one mutant allele is detected in another 1/4 of patient populations, and no mutations are de-tected in the other 1/2. The presence of two mutant al-leles of SLC26A4 is associated with abnormal iodide or-ganification, increased thyroid gland volume, increased severity of hearing loss, and bilateral EVA. The pres-ence of a single mutant allele of SLC26A4 is associated with normal iodide organification, normal thyroid gland volume, less severe hearing loss and either bilateral or unilateral EVA. When other underlying correlations are accounted for, the presence of a cochlear malformation or the size of EVA does not have an effect on hearing thresholds. This is consistent with observations of an Slc26a4 mutant mouse model of EVA in which hearing loss is independent of endolymphatic hydrops or in-ner ear malformations. Segregation analyses of EVA in families suggest that the patients carrying one mutant allele of SLC26A4 have a second, undetected mutant allele of SLC26A4, and the probability of a sibling hav-ing EVA is consistent with its segregation as an autoso-mal recessive trait. Patients without any mutations are an etiologically heterogeneous group in which siblings have a lower probability of having EVA. SLC26A4 muta-tion testing can provide prognostic information to guide clinical surveillance and management, as well as the probability of EVA affecting a sibling.展开更多
Backgroud Large vestibular aqueduct syndrome （LVAS） is a major cause of hearing loss in childhood. This study aimed at measuring external aperture of enlargement of the vestibular aqueduct （EVA） and analyzing rela...Backgroud Large vestibular aqueduct syndrome （LVAS） is a major cause of hearing loss in childhood. This study aimed at measuring external aperture of enlargement of the vestibular aqueduct （EVA） and analyzing relationship between the size of external aperture and hearing loss. Methods Diagnostic criteria of LVAS were based on hearing loss and CT images. CT images of temporal bone of 100 LVAS patients were collected and 60 control subjects were reviewed retrospectively in the past 10 years. A battery of audiometric and vestibular function tests were performed. The width of the vestibular aqueduct （VA） was measured on axial CT images of the temporal bone. Results One hundred patients （65 men, 35 women） were diagnosed as having the isolated EVA. Hearing loss mostly occurred in early childhood. The diagnosis age of LVAS was 7.7 years on average. The causes of hearing loss could not be confirmed by initial consult. Typically, audiometric curve is the high-frequency down-sloping configuration. 92% of the cases had severe or profound sonsorineural hearing loss （SNHL）. The mean size of the external aperture was （7.5±1.2） mm in present LVAS. Statistical analysis showed that the degree of hearing loss is unrelated to the width of VA. Conclusions LVAS is a distinct clinical entity characterized by fluctuating, progressive SNHL. The degree of hearing loss is unrelated to the size of external aperture of VA. The protective management and hearing aid have become the main therapies. The cochlear implantation might be performed if the hearing loss affected learning at school.展开更多
To the Editor:Drug-induced immune hemolytic anemia (DIIHA)is a rare but severe condition.Ceftriaxone,a third-generation cephalosporin with a wide antibacterial spectrum and effective antibacterial action,is one of the...To the Editor:Drug-induced immune hemolytic anemia (DIIHA)is a rare but severe condition.Ceftriaxone,a third-generation cephalosporin with a wide antibacterial spectrum and effective antibacterial action,is one of the most common drugs causing DIIHA.^[1]Ceftriaxoneinduced immune hemolytic anemia (CIIHA)is a potentially fatal complication.^[2]Most of the patients were children.The reported fatality rate of CIIHA was as high as 40%.展开更多
Growing interest in using Powdered Activated Carbon （PAC） in raw water aqueduct, as a method of polluted surface water treatment, raises the question of transport of PAC in the aqueduct, which is related to the pote...Growing interest in using Powdered Activated Carbon （PAC） in raw water aqueduct, as a method of polluted surface water treatment, raises the question of transport of PAC in the aqueduct, which is related to the potential PAC erosion along the aqueduct. By means of a recently developed re-circulating flume, erosion rates of PAC with the grain size of 230 meshes （less than 62μm） depending on shear stress and bulk density were the discussed with real-time measurement of suspended PAC concentration. Lateral cross sectional averaging shear stress was decided by the actual value in the raw water conveying aqueduct of upstream Huangpu River, Shanghai, China, smaller than 1.8 N＇m 2. As for the bulk density, it was measured with compacting times varying from 1 d to 15 d, equivalent to 1 550 kg/m3-1 800 kg/m3. Experiments were conducted for the shear stress and bulk density separately, so as to isolate and quantify the effects of one of the parameters. The results demonstrate that, for a particular PAC particle, the erosion rate increases with shear stress and decreases with bulk density as a function of power form. A product of powers of the lateral cross sectional averaging shear stress and bulk density to estimate PAC erosion rate is presented by approximating experimental data sets.展开更多
基金Science and Technology Planning Project of Sichuan Province with Grant No.2023YFS0429supported by Science and Technology Project of China Road and Bridge Corporation with Grant No.P2220447+1 种基金supported by Foundation of Xinjiang Institute of Engineering 2024(Grant No.2024xgy072605)supported by Sichuan Natural Science Foundation Project(Grant No.2024NSFSC0162).The numerical calculations in this study have been done on Hefei advanced computing center.
文摘In recent years,tuned liquid dampers(TLDs)have attracted significant research interest;however,overall progress has been limited due to insufficient understanding of the mechanisms governing sloshing-induced loads.In particular,it remains unclear whether the water in aqueducts—common water-diversion structures in many countries—can serve as an effective TLD.This study investigates the generation mechanisms of sloshing loads during the first-order transverse resonance of water in a U-shaped aqueduct using a two-dimensional(2D)numerical model.The results reveal that,at the equilibrium position,the free surface difference between the left and right walls,the horizontal force on the aqueduct,and the fluctuating component of the vertical force all reach their maxima,with energy predominantly stored as potential energy.At the maximum displacement position,the surface difference and horizontal force drop to zero,while the fluctuating vertical force attains its minimum and energy shifts primarily to kinetic form.At this stage,static pressure is governed solely by the vertical convective acceleration,whereas at equilibrium it is closely linked to both the free surface difference and vertical local acceleration of the water.This dynamic energy exchange generates vertical force oscillations even when the free surface appears nearly symmetric.
基金supported by Science and Technology Planning Project of Sichuan Province with Grant No.2023YFS0429supported by Science and Technology Project of China Road and Bridge Corporation with Grant No.P2220447+1 种基金supported by Foundation of Xinjiang Institute of Engineering 2024(Grant No.2024xgy072605)also supported by Sichuan Natural Science Foundation Project(Grant No.2024NSFSC0162).
文摘In recent years,tuned liquid dampers(TLDs)have emerged as a focal point of research due to their remarkable potential for structural vibration mitigation.Yet,progress in this field remains constrained by an incomplete understanding of the fundamental mechanisms governing sloshing-induced loads in liquid-filled containers.Aqueducts present a distinctive case,as the capacity of their contained water to function effectively as a TLD remains uncertain.To address this gap,the present study investigates the generation mechanisms of sloshing loads under non-resonant cases through a two-dimensional(2D)computational fluid dynamics(CFD)model developed in ANSYS Fluent.The incompressible Reynolds-Averaged Navier–Stokes(RANS)equations are solved,while the Volume of Fluid(VOF)method captures the evolution of the air–water interface.Turbulent flow behavior is modeled using the RNG-approach.The ensuing results reveal the dynamic characteristics of the horizontal force(fℎ)and the fluctuating component of the vertical force(Fof).Fh is predominantly governed by the inertia of the deep-water region and its phase varies coherently with the aqueduct’s acceleration.With increasing excitation amplitude(A)and frequency(f),the contribution of deep-water inertia to𝐹ℎintensifies markedly,accounting for 82.6–92.1%of the total horizontal load at an excitation amplitude of 0.15 m and frequencies of 1.0–1.6 Hz.The extreme values of Fof arise primarily from asymmetric static pressures induced by free-surface fluctuations,which are further amplified when wall gaps appear at large amplitudes(A≥10 cm)and high frequencies(f≥1.4 Hz).Unlike resonant cases dominated by free-surface resonance,non-resonant sloshing loads are principally driven by deep-water inertia and motion-induced surface asymmetry.
基金National Natural Science Foundation of China Under Grant No.50678121Open Research Fund Program of State key Laboratory of Hydro-science and Engineering
文摘In this paper, a full-scale 3-D finite element model of the Jundushan cable-stayed aqueduct bridge is established with ANSYS Code. The shell, fluid, tension-only spar and beam elements are used for modeling the aqueduct deck, filled water, cables and support towers, respectively. A multi-element cable formulation is introduced to simulate the cable vibration. The dry （without water） and wet （with water） modes of the aqueduct bridge are both extracted and investigated in detail. The dry modes of the aqueduct bridge are basically similar to those of highway cable-stayed bridges. A dry mode may correspond to two types of wet modes, which are called the in-phase （with lower frequency） and out-of-phase （with higher frequency） modes. When the water-structure system vibrates in the in-phase/out-of-phase modes, the aqueduct deck moves and water sloshes in the same/opposite phase-angle, and the sloshing water may take different surface-wave modes. The wet modes of the system reflect the properties of interaction among the deck, towers, cables and water. The in-phase wet frequency generally decreases as the water depth increases, and the out-of-phase wet frequency may increase or decrease as the water depth increases.
文摘Enlarged vestibular aqueduct(EVA), the most frequent identifiable cause of congenital hearing loss, is evaluated with high-definition multidetector CT in the axial plane. Our purpose was to determine which reformatted CT measurements are most reproducible. Seven multiplanar reformatted images were created for each of the 64 temporal bones in patients with EVA. Intraclass correlation coefficients(ICC) were used to assess inter-observer variability, and both linear regression and ROC analyses were used to compare the measurements with severity of hearing loss, as assessed by pure tone audiometry. All seven measurements had excellent inter-observer variability, with average-measure ICC ranging from 0.92 to 0.98. There was no statistically significant correlation between the radiologic degree of aqueduct enlargement and severity of hearing loss using any of the seven measurements; ROC analyses revealed areas under the curves ranging from 0.57 to 0.73. Optimal accuracy was obtained with a threshold of 1.75 mm as measured at the aqueductal aperture in the P€oschl plane, with sensitivity of 0.75 and specificity of0.63. Although the radiologic measurement may not serve as a reliable tool for assessing severity of EVA, P€oschl plane reformatting has proven to be better than conventional axial acquisition plane for identifying patients with clinically significant hearing loss.
基金Supported by NIH intramural research funds Z01-DC-000039,Z01-DC-000060 and Z01-DC-000064,NIH grants R01-DK43495 and P30-DK34854Kansas State University CVM-SMILE and the Kansas City Area Life Science Institute
文摘nPendred syndrome （PS） is characterized by autosomal recessive inheritance of goiter associated with a defect of iodide organification, hearing loss, enlargement of the vestibular aqueduct （EVA）, and mutations of the SLC26A4 gene. However, not all EVA patients have PS or SLC26A4 mutations. Two mutant alleles of SLC26A4 are detected in 1/4 of North American or European EVA populations, one mutant allele is detected in another 1/4 of patient populations, and no mutations are de-tected in the other 1/2. The presence of two mutant al-leles of SLC26A4 is associated with abnormal iodide or-ganification, increased thyroid gland volume, increased severity of hearing loss, and bilateral EVA. The pres-ence of a single mutant allele of SLC26A4 is associated with normal iodide organification, normal thyroid gland volume, less severe hearing loss and either bilateral or unilateral EVA. When other underlying correlations are accounted for, the presence of a cochlear malformation or the size of EVA does not have an effect on hearing thresholds. This is consistent with observations of an Slc26a4 mutant mouse model of EVA in which hearing loss is independent of endolymphatic hydrops or in-ner ear malformations. Segregation analyses of EVA in families suggest that the patients carrying one mutant allele of SLC26A4 have a second, undetected mutant allele of SLC26A4, and the probability of a sibling hav-ing EVA is consistent with its segregation as an autoso-mal recessive trait. Patients without any mutations are an etiologically heterogeneous group in which siblings have a lower probability of having EVA. SLC26A4 muta-tion testing can provide prognostic information to guide clinical surveillance and management, as well as the probability of EVA affecting a sibling.
文摘Backgroud Large vestibular aqueduct syndrome （LVAS） is a major cause of hearing loss in childhood. This study aimed at measuring external aperture of enlargement of the vestibular aqueduct （EVA） and analyzing relationship between the size of external aperture and hearing loss. Methods Diagnostic criteria of LVAS were based on hearing loss and CT images. CT images of temporal bone of 100 LVAS patients were collected and 60 control subjects were reviewed retrospectively in the past 10 years. A battery of audiometric and vestibular function tests were performed. The width of the vestibular aqueduct （VA） was measured on axial CT images of the temporal bone. Results One hundred patients （65 men, 35 women） were diagnosed as having the isolated EVA. Hearing loss mostly occurred in early childhood. The diagnosis age of LVAS was 7.7 years on average. The causes of hearing loss could not be confirmed by initial consult. Typically, audiometric curve is the high-frequency down-sloping configuration. 92% of the cases had severe or profound sonsorineural hearing loss （SNHL）. The mean size of the external aperture was （7.5±1.2） mm in present LVAS. Statistical analysis showed that the degree of hearing loss is unrelated to the width of VA. Conclusions LVAS is a distinct clinical entity characterized by fluctuating, progressive SNHL. The degree of hearing loss is unrelated to the size of external aperture of VA. The protective management and hearing aid have become the main therapies. The cochlear implantation might be performed if the hearing loss affected learning at school.
文摘To the Editor:Drug-induced immune hemolytic anemia (DIIHA)is a rare but severe condition.Ceftriaxone,a third-generation cephalosporin with a wide antibacterial spectrum and effective antibacterial action,is one of the most common drugs causing DIIHA.^[1]Ceftriaxoneinduced immune hemolytic anemia (CIIHA)is a potentially fatal complication.^[2]Most of the patients were children.The reported fatality rate of CIIHA was as high as 40%.
基金supported by the National Natural Science Foundation of China(Grant No.11102137)State Key Laboratory of Pollution Control and Resource Reuse Foundation,Tongji University(Grant No.PCRRY11009)the National High Technology Research and Development Program of China(863 Program,Grant No.2008AA06A412)
文摘Growing interest in using Powdered Activated Carbon （PAC） in raw water aqueduct, as a method of polluted surface water treatment, raises the question of transport of PAC in the aqueduct, which is related to the potential PAC erosion along the aqueduct. By means of a recently developed re-circulating flume, erosion rates of PAC with the grain size of 230 meshes （less than 62μm） depending on shear stress and bulk density were the discussed with real-time measurement of suspended PAC concentration. Lateral cross sectional averaging shear stress was decided by the actual value in the raw water conveying aqueduct of upstream Huangpu River, Shanghai, China, smaller than 1.8 N＇m 2. As for the bulk density, it was measured with compacting times varying from 1 d to 15 d, equivalent to 1 550 kg/m3-1 800 kg/m3. Experiments were conducted for the shear stress and bulk density separately, so as to isolate and quantify the effects of one of the parameters. The results demonstrate that, for a particular PAC particle, the erosion rate increases with shear stress and decreases with bulk density as a function of power form. A product of powers of the lateral cross sectional averaging shear stress and bulk density to estimate PAC erosion rate is presented by approximating experimental data sets.
