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Health behavior outcomes in stroke survivors prescribed wearables for atrial fibrillation detection stratified by age
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作者 Joanne Mathew Jordy Mehawej +11 位作者 Ziyue Wang Taylor Orwig Eric Ding Andreas Filippaios Syed Naeem Edith Mensah Otabil Alex Hamel Kamran Noorishirazi IrinaRadu Jane Saczynski David D.McManus Khanh-Van Tran 《Journal of Geriatric Cardiology》 SCIE CAS CSCD 2024年第3期323-330,共8页
BACKGROUND Smartwatches have become readily accessible tools for detecting atrial fibrillation(AF).There remains limited data on how they affect psychosocial outcomes and engagement in older adults.We examine the heal... BACKGROUND Smartwatches have become readily accessible tools for detecting atrial fibrillation(AF).There remains limited data on how they affect psychosocial outcomes and engagement in older adults.We examine the health behavior outcomes of stroke survivors prescribed smartwatches for AF detection stratified by age.METHODS We analyzed data from the Pulsewatch study,a randomized controlled trial that enrolled patients(≥50 years)with a history of stroke or transient ischemic attack and CHA2DS2-VASc≥2.Intervention participants were equipped with a cardiac patch monitor and a smartwatch-app dyad,while control participants wore the cardiac patch monitor for up to 44 days.We evaluated health behavior parameters using standardized tools,including the Consumer Health Activation Index,the Generalized Anxiety Disorder questionnaire,the 12-Item Short Form Health Survey,and wear time of participants categorized into three age groups:Group 1(ages 50-60),Group 2(ages 61-69),and Group 3(ages 70-87).We performed statistical analysis using a mixedeffects repeated measures linear regression model to examine differences amongst age groups.RESULTS Comparative analysis between Groups 1,2 and 3 revealed no significant differences in anxiety,patient activation,perception of physical health and wear time.The use of smartwatch technology was associated with a decrease in perception of mental health for Group 2 compared to Group 1(β=-3.29,P=0.046).CONCLUSION Stroke survivors demonstrated a willingness to use smartwatches for AF monitoring.Importantly,among these study participants,the majority did not experience negative health behavior outcomes or decreased engagement as age increased. 展开更多
关键词 PRESCRIBED stratified WEAR
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Finite Difference Approach on Magnetohydrodynamic Stratified Fluid Flow Past Vertically Accelerated Plate in Porous Media with Viscous Dissipation
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作者 M.Sridevi B.Shankar Goud +1 位作者 Ali Hassan D.Mahendar 《Frontiers in Heat and Mass Transfer》 EI 2024年第3期939-953,共15页
This study intends to evaluate the influence of temperature stratification on an unsteady fluid flow past an accelerated vertical plate in the existence of viscous dissipation.It is assumed that the medium under study... This study intends to evaluate the influence of temperature stratification on an unsteady fluid flow past an accelerated vertical plate in the existence of viscous dissipation.It is assumed that the medium under study is a grey,non-scattered fluid that both fascinates and transmits radiation.The leading equations are discretized using the finite differencemethod(FDM).UsingMATLABsoftware,the impacts of flowfactors on flowfields are revealed with particular examples in graphs and a table.In this regard,FDM results show that the velocity and temperature gradients increase with an increase of Eckert number.Furthermore,tables of the data indicate the influence of flow-contributing factors on the skin friction coefficients,and Nusselt numbers.When comparing constant and variable flow regimes,the constant flow regime has greater values for the nondimensional skin friction coefficient.This research is both innovative and fascinating since it has the potential to expand our understanding of fluid dynamics and to improve many different sectors. 展开更多
关键词 MHD FDM stratified fluid porous media unsteady flow
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Application Effect of Stratified Nursing Intervention for ICU Mechanically Ventilated Patients in the Context of Aspiration Risk Assessment
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作者 Caisu Qin Yong Gao +1 位作者 Yanchi Zheng Wenjuan Wang 《Journal of Clinical and Nursing Research》 2024年第6期226-231,共6页
Objective:To explore the application effect of stratified nursing intervention based on the background of misinspiration risk assessment in mechanically ventilated patients in intensive care unit(ICU).Methods:100 case... Objective:To explore the application effect of stratified nursing intervention based on the background of misinspiration risk assessment in mechanically ventilated patients in intensive care unit(ICU).Methods:100 cases of mechanically ventilated patients who were admitted to the ICU of our hospital from March 2022 to March 2023 were selected and divided into an observation group and a control group according to the random number table method,with 50 cases in each of the two groups.The control group was given routine care in ICU,and the observation group was given stratified nursing interventions based on the background of the risk of aspiration assessment on the basis of the control group,and both groups were cared for until they were transferred out of the ICU,and the mechanical ventilation time,ICU stay time,muscle strength score,complication rate,adherence,and satisfaction were observed and compared between the two groups.Results:The mechanical ventilation time and ICU stay time of the observation group were shorter than that of the control group after the intervention;the muscle strength score,compliance and satisfaction of the observation group were higher than that of the control group after the intervention;and the complication rate of the observation group was lower than that of the control group after the intervention,all of which were P<0.05.Conclusion:The application of stratified nursing intervention based on the background of misaspiration risk assessment in ICU mechanically ventilated patients can improve the patient's muscle strength,shorten the time of mechanical ventilation,promote the patient's recovery,reduce the occurrence of complications,and improve the patient's compliance and satisfaction. 展开更多
关键词 Mechanical ventilation Aspiration risk assessment stratified care Muscle strength COMPLICATION
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Singularity-free Green's function for EM sources embedded in a stratified medium 被引量:3
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作者 翁爱华 刘云鹤 +1 位作者 殷长春 贾定宇 《Applied Geophysics》 SCIE CSCD 2016年第1期25-36,217,218,共14页
We present a method to unify the calculation of Green's functions for an electromagnetic(EM) transmitting source embedded in a homogeneous stratified medium.A virtual interface parallel to layer interfaces is intro... We present a method to unify the calculation of Green's functions for an electromagnetic(EM) transmitting source embedded in a homogeneous stratified medium.A virtual interface parallel to layer interfaces is introduced through the source location.The potentials for Green's function are derived by decomposing the partial wave solutions to Helmholtz's equations into upward and downward within boundaries.The amplitudes of the potentials in each stratum are obtained recursively from the initial amplitudes at the source level.The initial amplitudes are derived by coupling with the transmitting sources and following the discontinuity of the tangential electric and magnetic fields at the source interface.Only the initial terms are related to the transmitting sources and thus need to be modified for different transmitters,whereas the kernel connected with the stratified media stays unchanged.Hence,the present method can be easily applied to EM transmitting sources with little modification.The application of the proposed method to the marine controlled-source electromagnetic method(MCSEM) demonstrates its simplicity and flexibility. 展开更多
关键词 EM Marine EM Green's function stratified medium SINGULARITY
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On The Necessity of Stratified English Teaching in Higher Vocational Colleges
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作者 张天华 《海外英语》 2013年第16期53-54,共2页
The practice of stratified English teaching is determined by the features of vocational education. In addition, it is an inexorable trend of current higher education reform, and also a fundamental demand of higher voc... The practice of stratified English teaching is determined by the features of vocational education. In addition, it is an inexorable trend of current higher education reform, and also a fundamental demand of higher vocational education and quality-oriented education. This thesis argues for the need of stratified English teaching in high vocational colleges. 展开更多
关键词 Higher VOCATIONAL COLLEGES stratified English TEAC
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Metallogenetic Mechanism and Timing of Late Superimposing Fluid Mineralization in the Dongguashan Diplogenetic Stratified Copper Deposit,Anhui Province 被引量:21
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作者 XUZhaowen LUXiancai +5 位作者 LINGHongfei LUJianjun JIANGShoyong NIEGuiping HUANGShunsheng HUAMing 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2005年第3期405-413,共9页
An important diplogenetic mineralization event superimposed on pre-existing exhalation sediments in the Tongling area, Anhui province, was triggered by widespread granitic magmatism along the northeastern margin of th... An important diplogenetic mineralization event superimposed on pre-existing exhalation sediments in the Tongling area, Anhui province, was triggered by widespread granitic magmatism along the northeastern margin of the Yangtze Block during 140–135 Ma under extensional tectonic circumstances following the collision between the North China and Yangtze blocks. The main orebodies of the Dongguashan copper deposit, a typical diplogenetic stratified deposit among many polymetallic ore deposits in China, are hosted by strata between Upper Devonian sandstone and Carboniferous limestone, and its mineralization was genetically related to the Qingshanjiao intrusive. The Rb-Sr isotopic isochron of the Qingshanjiao intrusive yields an age of about 136.5±1.4 Ma. The ore-forming fluid reflected by the inclusion fluid in quartz veins is characterized by high temperature and high salinity, and its age was also determined by Rb -Sr isotope dating as 134±11 Ma. Oxygen and hydrogen isotope composition data suggest that the ore-forming fluid was derived mainly from magmatism. By integrating these isotopic dating data, characteristics of fluid inclusions and the geology of the deposit, the mineralization of the Dongguashan copper deposit is divided into two stages. First, a stratiform sedimentary deposit or protore layer formed in the Late Devonian to the Early Carboniferous, while in the second stage the pre-existing protore was superimposed by hydrothermal fluid that was derived from the Yanshanian magmatic activities occurring around 135 Ma ago. This two-stage mineralization formed the Dongguashan statiform copper deposit. Associated “porphyry” mineralization found in the bottom of and in surrounding intrusive rocks of the orebodies might have occurred in the same period as a second-stage mineralization of this deposit. 展开更多
关键词 stratified copper deposit hydrothermal diplogenetic mineralization fluid inclusion metallogenetic epoch
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Gas-water stratified flow patterns from electromagnetic tomography 被引量:7
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作者 Wang Xiaoxing Wu Xiling 《Petroleum Science》 SCIE CAS CSCD 2009年第3期254-258,共5页
Because of gravitational differentiation of multi-phase fluids, gas-water flow is usually stratified in highly inclined or horizontal gas wells. By using electrode arrays to scan flowing fluids, electromagnetic tomogr... Because of gravitational differentiation of multi-phase fluids, gas-water flow is usually stratified in highly inclined or horizontal gas wells. By using electrode arrays to scan flowing fluids, electromagnetic tomography can identify the flow patterns of mixed fluid from the different electrical properties of gas and water. The responses for different gas-water interface locations were calculated and then physical measurements were undertaken. We compared the results of the numerical simulation with the experimental data, and found that the response characteristics were consistent in the circumstances of uniform physical fields and stratified flows. By analyzing the signal characteristics, it is found that, with the change of the interface location, the response curves showed "steps" whose position and width were decided by the location of fluid interface. The measurement accuracy of this method depended on the vertical distance between adjacent electrodes. The results showed that computer simulation can simulate the measurement of the electromagnetic tomography accurately, so the physical experiment can be replaced. 展开更多
关键词 Electromagnetic tomography stratified flow GAS-WATER numerical simulation physical experiment
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A novel method for chemistry tabulation of strained premixed/stratified flames based on principal component analysis 被引量:4
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作者 Peng TANG Hongda ZHANG +2 位作者 Taohong YE Zhou YU Zhaoyang XIA 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2018年第6期855-866,共12页
The principal component analysis (PCA) is used to analyze the high dimen- sional chemistry data of laminar premixed/stratified flames under strain effects. The first few principal components (PCs) with larger cont... The principal component analysis (PCA) is used to analyze the high dimen- sional chemistry data of laminar premixed/stratified flames under strain effects. The first few principal components (PCs) with larger contribution ratios axe chosen as the tabu- lated scalars to build the look-up chemistry table. Prior tests show that strained premixed flame structure can be well reconstructed. To highlight the physical meanings of the tabu- lated scalars in stratified flames, a modified PCA method is developed, where the mixture fraction is used to replace one of the PCs with the highest correlation coefficient. The other two tabulated scalars are then modified with the Schmidt orthogonalization. The modified tabulated scalars not only have clear physical meanings, but also contain passive scalars. The PCA method has good commonality, and can be extended for building the thermo-chemistry table including strain rate effects when different fuels are used. 展开更多
关键词 premixed flame stratified flame strain rate principal component analysis(PCA) chemistry table
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Modelling the flexural buckling failure of stratified rock slopes based on the multilayer beam model 被引量:2
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作者 ZHANG Yan-jun NIAN Ting-kai +2 位作者 GUO Xing-sen CHEN Guang-qi ZHENG Lu 《Journal of Mountain Science》 SCIE CSCD 2019年第5期1170-1183,共14页
The buckling failure of stratified rock slopes intersected by a set of steep discontinuities that are approximately parallel to the slope surface is frequently encountered while constructing railways and roadways in m... The buckling failure of stratified rock slopes intersected by a set of steep discontinuities that are approximately parallel to the slope surface is frequently encountered while constructing railways and roadways in mountainous areas. In this study, an analytical approach based on the energy equilibrium principle is presented to solve the flexural buckling stability of stratified rock slopes within the framework of multilayer beam theory. The generalized HoekBrown failure criterion is introduced to reflect the influences of slope size(scale effects) on the buckling stability. Subsequently, numerical and physical modellings from previous literatures are employed to validate the proposed approach. Furthermore, a practical case of Bawang Mountain landslide is also used for the comparative analysis. The study shows that the present analytical approach is capable to provide a more reasonable assessment for the buckling failure of stratified rock slopes, compared with several existing analytical approaches. Finally, a detailed parametric study is implemented, and the results indicate that the effects of rock strength, rock deformation modulus, geological strength index, layer thickness and disturbance degree of rock mass on the buckling failure of stratified rock slopes are more significant than that of rock type and slope angle. 展开更多
关键词 SLOPE stability stratified rock BUCKLING Scale effect Bawang MOUNTAIN
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Mechanical properties and failure modes of stratified backfill under triaxial cyclic loading and unloading 被引量:14
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作者 Wang Jie Song Weidong +1 位作者 Cao Shuai Tan Yuye 《International Journal of Mining Science and Technology》 SCIE EI CSCD 2019年第5期809-814,共6页
Multiple filling of gobs will lead to a layered structure of the backfill.To explore the influence of layering structure on the mechanical properties and failure modes of backfill,different backfill specimens were pre... Multiple filling of gobs will lead to a layered structure of the backfill.To explore the influence of layering structure on the mechanical properties and failure modes of backfill,different backfill specimens were prepared with a cement/sand ratio of 1:4,a slurry concentration of 75%,and backfilling times of 1,2,3 and 4,separately.Triaxial cyclic loading and unloading experiments were carried out.The results show that with an increase in backfilling time,the peak strength of backfill decreases as a polynomial function and the peak strain increases as an exponential function.The cyclic load enhances the linear characteristic of backfill deformation.The loading and unloading deformation moduli have a linear negative correlation with the backfilling time.The unloading deformation modulus is always slightly higher than the loading deformation modulus.The failure modes of stratified backfill are mainly characterized by conjugate shear failure at the upper layer and tensile failure across the layer plane,and there is usually no damage in the lower layer away from the loading area. 展开更多
关键词 stratified BACKFILL TRIAXIAL cyclic loading and UNLOADING Mechanical properties Failure MODES Deformation MODULUS
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Predicting suitability of different scale-dependent dispersivities for reactive solute transport through stratified porous media 被引量:2
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作者 Deepak Swami Abhimanyu Sharma +1 位作者 Pramod Kumar Sharma Dericks P.Shukla 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2016年第6期921-927,共7页
In this paper,the behavior of breakthrough curves(BTCs) for reactive solute transport through stratified porous media is investigated.A physical laboratory model for layered porous media was constructed,in which thin ... In this paper,the behavior of breakthrough curves(BTCs) for reactive solute transport through stratified porous media is investigated.A physical laboratory model for layered porous media was constructed,in which thin layer of gravel was sandwiched in between two thick layers of natural soil.Gravel layer and natural soil layers were hydraulically connected as single porous continuum.A constant source of tracer was connected through gravel layer and elucidated at different sampling points in the direction of flow.Flexible multiprocess non-equilibrium(MPNE) transport equation with scale-dependent dispersivity function was used to simulate experimental BTCs of reactive solute transport through layered porous media.The values of equilibrium sorption coefficient and other input parameters were obtained experimentally.The simulation of BTC was performed using MPNE model with scale-dependent dispersivity.The simulation of different scale-dependent dispersivities was then compared and it was found that for field scale of estimation of dispersivity,asymptotic and exponential dispersivity functions performed better.In continuation to the comparison of simulated BTCs obtained using different models,spatial moment analysis of each aforesaid scale-dependent dispersivity model was also done.Spatial moment analysis provides the information related to mean solute mass,rate of mass travel,and mean plume dispersion.Linear and constant dispersivities showed higher variance as compared to asymptotic and exponential dispersion functions.This supports the field applicability of asymptotic and exponential dispersivity functions.The BTCs were also found to elucidate a nonzero concentration with time,which was clearly affected by physical non-equilibrium.In natural condition,such information is required in effective aquifer remediation process. 展开更多
关键词 Multiprocess non-equilibrium(MPNE) Scale-dependent dispersivity stratified porous media Spatial moment
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NLS EQUATION OF INTERNAL WAVES IN WEAKLY STRATIFIED OCEAN 被引量:1
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作者 徐肇廷 楼顺里 田纪伟 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 1996年第2期121-127,共7页
The NLS (Non-Linear Schr(?)dinger) equation of internal waves in a wekly stratified ocean is der-ived in phase coordnates in terms of the RPM (Reductive Perturbation Method). It was shown thatwhen AB】0 there exist mo... The NLS (Non-Linear Schr(?)dinger) equation of internal waves in a wekly stratified ocean is der-ived in phase coordnates in terms of the RPM (Reductive Perturbation Method). It was shown thatwhen AB】0 there exist modulation forms of envelope soliton and dn, and tha when AB【0 there arethree modulation forms dark soliton, sn and cn. Only if K^2】B/A(?) . the side-band perturbation is stable,otherwise unstable. For the stable side-band perturbation there ekisis a modulation form of MdV soliton. 展开更多
关键词 WEAKLY stratified OCEAN MLS equation INTERNAL WAVES
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Near Wake of a Horizontal Circular Cylinder in Stably Stratified Flows 被引量:3
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作者 Yuji Ohya Takanori Uchida Tomoyuki Nagai 《Open Journal of Fluid Dynamics》 2013年第4期311-320,共10页
The near wake of a circular cylinder in linearly stratified flows of finite depth was experimentally investigated by means of flow visualization and measurements of vortex shedding frequencies, at Reynolds numbers 3.5... The near wake of a circular cylinder in linearly stratified flows of finite depth was experimentally investigated by means of flow visualization and measurements of vortex shedding frequencies, at Reynolds numbers 3.5 × 103-1.2 × 104 and stratification parameters kd 0-2.0. The non-dimensional parameter kd is defined as kd = Nd/U, where N is the Brunt-Vaisala frequency, d, the diameter of the cylinder, and U, the approaching flow velocity. The study demonstrates that as kd increases from zero, the vortex shedding from a circular cylinder progressively strengthens, while the Strouhal number gradually becomes lower than that for homogeneous flow. This phenomenon can be explained by the effect of the increasingly stable stratification which enhances the two-dimensionality of the near-wake flow of the circular cylinder;the enhanced two-dimensionality of the flow strengthens the roll-up of the separated shear layer. Above a certain value of kd, however, vortex formation and shedding are strongly suppressed and the Strouhal number rises sharply. This observation is attributable to the development of stationary lee waves downstream of the circular cylinder because the lee waves strongly suppress vertical fluid motions. 展开更多
关键词 stratified Flow Circular CYLINDER WAKE Pattern VORTEX SHEDDING LEE Wave
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Application of CPD in Analyzing EM Field in Stratified Media with an Uniform Plane Wave Slanted Through 被引量:2
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作者 张清毅 朱建铭 《International Journal of Mining Science and Technology》 SCIE EI 1999年第2期187-191,共5页
The Counter-Propagation Deduction (CPD) method suggested by the authors is a new one for analyzing electromagnetic (EM) field in stratified media. The mechanism or the method is briefly introduced, and the rield in a ... The Counter-Propagation Deduction (CPD) method suggested by the authors is a new one for analyzing electromagnetic (EM) field in stratified media. The mechanism or the method is briefly introduced, and the rield in a layered medium in the presence or slant incidence of a perpendicularly or parallelly polarized electric wave is investigated. Some illustrative examples show that the method is capable of providing the direct mathematic expressions of the fields in an arbitrary layer, and is convenient for numerical evaluation through an unified program, irrespective of the number of medium layers. 展开更多
关键词 stratified media counter-propagation DEDUCTION (CPD)method boundary-originated set (BOS) of WAVES perpendicularly POLARIZED WAVES parallelly POLARIZED WAVES
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Failure mode and strength anisotropic characteristic of stratified rock mass under uniaxial compressive situation 被引量:4
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作者 鲁光银 朱自强 +1 位作者 柳群义 何现启 《Journal of Central South University》 SCIE EI CAS 2009年第4期663-668,共6页
A stratified rock mass model was founded by FLAC^3D. The failure mode and anisotropic characteristic of strength for stratified rock mass were analyzed. The analysis results show that the numerical simulation can visu... A stratified rock mass model was founded by FLAC^3D. The failure mode and anisotropic characteristic of strength for stratified rock mass were analyzed. The analysis results show that the numerical simulation can visually reflect the failure modes of rock samples under different inclination angles β of structural plane. The stiffness of rock sample before peak strength changes in the compressive procedure. With the increase of β, the compressive strength σc of rock sample decreases firstly and then increases; when β is in the range of 20°-30° and 80°-90°, σc has the largest sensitivity to r; while β falls in the range of 30°-70°, σc varies little. When φj〈β〈90° ( φj is friction angle of structure plane), the results obtained from numerical simulation and theoretical analysis are in almost the same values; while β〈 φj or β=90°, they are in great different values. The results obtained from theoretical analysis are obvious larger than those from numerical simulation; and the results from numerical simulation can reflect the difference of compressive strength of rock samples for the two situations of β≥φj and β=90°, which is in more accordance with the real situation. 展开更多
关键词 stratified rock mass failure mode STRENGTH anisotropic characteristic numerical analysis
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Analysis of current induced by long internal solitary waves in stratified ocean 被引量:1
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作者 Hui-Qin Zhang Jia-Chun Li 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2010年第5期653-660,共8页
An approximate theoretical expression for the current induced by long internal solitary waves is presented when the ocean is continuously or two-layer stratified. Particular attention is paid to characterizing velocit... An approximate theoretical expression for the current induced by long internal solitary waves is presented when the ocean is continuously or two-layer stratified. Particular attention is paid to characterizing velocity fields in terms of magnitude, flow components, and their temporal evolution/spatial distribution. For the two-layer case, the effects of the upper/lower layer depths and the relative layer density difference upon the induced current are further studied. The results show that the horizontal components are basically uniform in each layer with a shear at the interface. In contrast, the vertical counterparts vary monotonically in the direction of the water depth in each layer while they change sign across the interface or when the wave peak passes through. In addition, though the vertical components are generally one order of magnitude smaller than the horizontal ones, they can never be neglected in predicting the heave response of floating platforms in gravitationally neutral balance. Comparisons are made between the partial theoretical results and the observational field data. Future research directions regarding the internal wave induced flow field are also indicated. 展开更多
关键词 Induced current Internal solitary waves stratified flow Two-layer fluid Asymptotic analysis
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Effects of Second Order Scattered Wave in Stratified Ocean 被引量:1
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作者 黄华 詹杰民 +1 位作者 朱顶金 廖德驹 《Marine Science Bulletin》 CAS 2001年第1期9-18,共10页
By using the theories on Stokes multicolored water waves and taking the two- layer ocean as a basic model of stratified ocean, the paper analyzes the problems related to the effects of the nonlinear water wave on offs... By using the theories on Stokes multicolored water waves and taking the two- layer ocean as a basic model of stratified ocean, the paper analyzes the problems related to the effects of the nonlinear water wave on offshore structures. A mathematical expression is presented to describe second order wave radiation conditions. Using integral principle, the analytical integral solutions are given to evaluate second order scattered wave loads on general vertical circular cylinders in the two-layer ocean, and the special recurrence formulas for infinite integrals over free and stratified surfaces are derived. 展开更多
关键词 stratified ocean SECOND order wave two layer ocean scattering diffracting WAVE load
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Stability of Stratified Gas-Liquid Flow in Horizontal and Near Horizontal Pipes 被引量:3
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作者 顾汉洋 郭烈锦 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2007年第5期619-625,共7页
A viscous Kelvin-Helmholtz criterion of the interfacial wave instability is proposed in this paper based on the linear stability analysis of a transient one-dimensional two-fluid model. In thismodel, the pressure is e... A viscous Kelvin-Helmholtz criterion of the interfacial wave instability is proposed in this paper based on the linear stability analysis of a transient one-dimensional two-fluid model. In thismodel, the pressure is evaluated using the local momentum balance rather than the hydrostatic approximation. The criterion predicts well the stability limit of stratified flow in horizontal and nearly horizontal pipes. The experimental and theoretical investigation on the effect of pipe inclination on the interfacial instability are carded out. It is found that the critical liquid height at the onset of interfacial wave instability is insensitive to the pipe inclination. However, the pipe inclination significantly affects critical superficial liquid velocity and wave velocity especially lor low gas velocities. 展开更多
关键词 two-fluid model Kelvin-Helmholtz criterion interfacial instability gas-liquid stratified flow
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The determination of the relative permittivity of periodic stratified media based on the iterative time-reversal method 被引量:1
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作者 章志敏 王秉中 +2 位作者 梁木生 纪晴 宋钢兵 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第4期694-699,共6页
In this paper, we present a new method to determine the relative permittivity of periodic stratified media using the iterative time-reversal method. Based on transmission line theory, the focal peak value of iterative... In this paper, we present a new method to determine the relative permittivity of periodic stratified media using the iterative time-reversal method. Based on transmission line theory, the focal peak value of iterative time-reversal electro- magnetic waves, which contain information about the periodic stratified medium, is computed in pulse-echo mode. Using the relationship between the focal peak value and the relative permittivity of the periodic stratified medium, the relative permittivity can be obtained by measuring the focal peak value. Numerical simulations are conducted, and the results demonstrate the feasibility of the proposed approach to the measurement of the relative permittivity of a periodic stratified medium. 展开更多
关键词 iterative time reversal periodic stratified medium peak value detection relative permittivity determination
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Large eddy simulation of turbulent premixed and stratified combustion using flame surface density model coupled with tabulation method 被引量:1
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作者 Zhou YU Hongda ZHANG +1 位作者 Taohong YE Minming ZHU 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2018年第12期1719-1736,共18页
Large eddy simulations(LESs) are performed to investigate the Cambridge premixed and stratified flames, SwB1 and SwB5, respectively. The flame surface density(FSD) model incorporated with two different wrinkling facto... Large eddy simulations(LESs) are performed to investigate the Cambridge premixed and stratified flames, SwB1 and SwB5, respectively. The flame surface density(FSD) model incorporated with two different wrinkling factor models, i.e., the Muppala and Charlette2 wrinkling factor models, is used to describe combustion/turbulence interaction, and the flamelet generated manifolds(FGM) method is employed to determine major scalars. This coupled sub-grid scale(SGS) combustion model is named as the FSD-FGM model. The FGM method can provide the detailed species in the flame which cannot be obtained from the origin FSD model. The LES results show that the FSD-FGM model has the ability of describing flame propagation, especially for stratified flames. The Charlette2 wrinkling factor model performs better than the Muppala wrinkling factor model in predicting the flame surface area change by the turbulence.The combustion characteristics are analyzed in detail by the flame index and probability distributions of the equivalence ratio and the orientation angle, which confirms that for the investigated stratified flame, the dominant combustion modes in the upstream and downstream regions are the premixed mode and the back-supported mode, respectively. 展开更多
关键词 large eddy simulation(LES) flame surface density(FSD) model TABULATION premixed combustion stratified combustion
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