Crustal Composition of China Continent Constrained from Heat Flow Data and Helium Isotope Ratio of Underground Fluid

Based on conservation of energy principle and heat flow data in China continent, the upper limit of 1.3 μW/m3 heat production is obtained for continental crust in China. Furthermore, using the data of heat flow and helium isotope ratio of underground fluid, the heat productions of different tectonic units in China continent are estimated in range of 0.58-1.12 μW/m3 with a median of 0.85 μW/m3. Accordingly, the contents of U, Th and K20 in China crust are in ranges of 0.83-1.76 μg/g, 3.16-6.69 μg/g, and 1.0%-2.12%, respectively. These results indicate that the abundance of radioactive elements in the crust of China continent is much higher than that of Archean crust; and this fact implies China＇s continental crust is much evolved in chemical composition. Meanwhile, significant lateral variation of crustal composition is also exhibited among different tectonic units in China continent. The crust of eastern China is much enriched in incompatible elements such as U, Th and K than that of western China; and the crust of orogenic belts is more enriched than that of platform regions. It can also be inferred that the crusts of eastern China and orogenic belts are much felsic than those of western China and platform regions, respectively, derived from the positive correlation between the heat production and SiO2 content of bulk crust. This deduction is consistent with the results derived from the crustal seismic velocity data in China. According to the facts of the lower seismic velocity of China than the average value of global crust, and the higher heat production of China continent compared with global crust composition models published by previous studies, it is deduced that the average composition models of global continent crust by Rudnick and Fountain （1995）, Rudnick and Gao （2003）, Weaver and Tarney （1984）, Shaw et al. （1986）, and Wedepohl （1995） overestimate the abundance of incompatible elements such as U, Th and K of continental crust.

Yield ratios and directed flows of light particles from proton-rich nuclei-induced collisions

The neutron-to-proton and3 H-to-3 He yield ratios, and the directed flows of particles dependent on a reduced rapidity, the transverse momentum per nucleon,and a reduced impact parameter are investigated for ^(28)S+^(28)Si and ^(32)S+^(28)Si systems at 50 and 400 MeV/u using an isospin-dependent quantum molecular dynamics model.The results show that these yield ratios of projectile-like fragments are approximately equal to the constituent neutron-to-proton ratio of the projectile. There are clear differences of the directed flows for isospin-related fragments neutron and proton,~3H and ~3He from ^(28)S+^(28)Si collisions.The differences in directed flows for neutrons and protons and ~3H–~3He from a proton-rich nucleus ^(28)S- induced collisions are noticeably larger than those from a stable nucleus ^(32)S- induced reactions under medium impact parameters. Thus, the yield ratios and differences in directed flows for the neutrons and protons and ~3H–~3He under medium impact parameters are proposed as possible observable items for studying isospin physics.

Determination of optimal blowing-to-suction flow ratio in mechanized excavation face with wall-mounted swirling ventilation using numerical simulations

Wall-mounted swirling ventilation is a new type of system in mechanized excavation faces with a dust sup-pression performance that is closely related to the blowing-to-suction flow ratio.Physical and simulation models were developed according to the No.C103 mechanized excavation face in the Nahe Coal Mine of the Baise Mining Bureau,Guangxi Province to optimize the blowing-to-suction flow ratio for wall-mounted swirling ventilation.Both the k-εturbulence model and the discrete phase model were utilized to simulate airflow field structures and dust concentration distribution patterns at various blowing-to-suction flow ratios.The results suggest that higher blowing-to-suction flow ratios increase the airflow field disturbance around the working face and weaken the intensity of the axial air curtain.On the other hand,both the intensity of the radial air curtain and the dust suppression effect are enhanced.At a blowing-to-suction flow ratio of 0.8,the wall-mounted swirling ventilation system achieved the most favorable dust suppression performance.Both the total dust and respirable dust had their lowest concentrations with maximum efficiencies of reducing both types at 90.33%and 87.16%,respectively.

Debris flow impact on flexible barrier: effects of debrisbarrier stiffness and flow aspect ratio

Conventionally,flexible barriers are rated based on their ability to resist a free-falling boulder with a particular input energy.However,there is still no well-accepted approach for evaluating performance of flexible barrier under debris flow impact.In this study,a large-nonlinear finite-element model was used to back-analyze centrifuge tests to discern the effects of impact material type,barrier stiffness,and flow aspect ratio(flow height to flow length)on the reaction force between the impacting medium and flexible barrier.Results show that,in contrast to flexible barriers for resisting rockfall,the normal impact force induced by the highly frictional and viscous debris is insensitive to barrier stiffness.This is because the elongated distributions of kinetic energy are mainly dissipated by the internal and boundary shearing,and only a small portion is forwarded to the barrier.Furthermore,a new stiffness number is proposed to characterize the equivalent stiffness between a debris flow or a boulder,and a flexible barrier.Under the circumstance of an extremely elongated debris flow event,i.e.,low aspect ratio,the load on a barrier is dominated by the static component and thus not sensitive to the barrier stiffness.

Quantitative flow ratio and intravascular ultrasound guided percutaneous coronary intervention of left anterior descending lesion concomitant with severe coronary myocardial bridge

Severe coronary stenosis concomitant with congenital coronary myocardial bridge(MB)is a tough scenario for cardiologist to perform revascularization,for which the complication rates including in-stent restenosis,stent fracture,stent thrombosis and even coronary perforation are still high.[1,2]Meanwhile,the necessity of revascularization in such patients is worth prudent evaluation.Cardiac imaging modalities are crucial and helpful in making revascularized decisions and strategies.Herein,we report a case using quantitative flow ratio(QFR)and intravascular ultrasound(IVUS)to facilitate accurate revascularization in a patient with both severe coronary stenosis and deep coronary MB.

Influence of Rotating Speed Ratio on the Annular Turbulent Flow between Two Rotating Cylinders

Rotating flows represent a very interesting area for researchers and industry for their extensive use in industrial and domestic machinery and especially for their great energy potential, annular flows are an example that draws the attention of researchers in recent years. The best design and optimization of these devices require knowledge of thermal, mechanical and hydrodynamic characteristics of flows circulating in these devices. An example of hydrodynamic parameters is the speed of rotation of the moving walls. This work is to study numerically the influence of the rotating speed ratio Γ of the two moving cylinders on the mean and especially on the turbulent quantities of the turbulent flow in the annular space. The numerical simulation is based on one-point statistical modeling using a low Reynolds number second-order full stress transport closure (RSM model), simulation code is not a black box but a completely transparent code where we can intervene at any step of the calculation. We have varied Γ from -1.0 to 1.0 while maintaining always the external cylinder with same speed Ω. The results show that the turbulence structure, profiles of mean velocities and the nature of the boundary layers of the mobile walls depend enormously on the ratio of speeds. The level of turbulence measured by the kinetic energy of turbulence and the Reynolds stresses shows well that the ratio Γ is an interesting parameter to exploit turbulence in this kind of annular flows.

The Effect of the Gap Ratio on the Flow and Heat Transfer over a Bluff Body in Near-Wall Conditions

In order to study the effect of different gap ratios on the thermofluid-dynamic field around a bluff body located in proximity to a heated wall,a series of experiments and numerical simulations have been conducted.The former were carried out using an open circulating water tank experimental platform and a single cylinder and square column as geometrical models(their characteristic length being D).The latter were based on the well-known SIMPLE algorithm for incompressible flow.The results show that the gap ratio is an important factor affecting the wake characteristics of near-wall bluff bodies.When the gap ratio is small,the influence of the wall on the bluff body wake is large.With an increase in the gap extension,periodic vortex shedding is enabled and heat transfer is strengthened accordingly;in addition,the vortex shedding period is larger for the square column.The square column displays hysteresis compared with the cylinder at the same gap ratio(the critical gap ratio of cylinder is 0.2~0.4,while that of square column is 0.4
0.6).

Air flow control based on optimal oxygen excess ratio in fuel cells for vehicles

Air flow control is one of the most important control methods for maintaining the stability and reliability of a fuel cell system, which can avoid oxygen starvation or oxygen saturation. The oxygen excess ratio （OER） is often used to indicate the air flow condition. Based on a fuel cell system model for vehicles, OER performance was analyzed for different stack currents and temperatures in this paper, and the results show that the optimal OER was affected weakly by the stack temperature. In order to ensure the system working in optimal OER, a control scheme that includes an optimal OER regulator and a fuzzy control was proposed. According to the stack current, a reference value of air flow rate was obtained with the optimal OER regulator and then the air compressor motor voltage was controlled with the fuzzy controller to adjust the air flow rate provided by the air compressor. Simulation results show that the control method has good dynamic and static characteristics.

Application of empirical mode decomposition based energy ratio to vortex flowmeter state diagnosis

To improve the measurement performance, a method for diagnosing the state of vortex flowmeter under various flow conditions was presented. The raw sensor signal of the vortex flowmeter was adaptively decomposed into intrinsic mode functions using the empirical mode decomposition approach. Based on the empirical mode decomposition results, the energy of each intrinsic mode function was extracted, and the vortex energy ratio was proposed to analyze how the perturbation in the flow affected the measurement performance of the vortex flowmeter. The relationship between the vortex energy ratio of the signal and the flow condition was established. The results show that the vortex energy ratio is sensitive to the flow condition and ideal for the characterization of the vortex flowmeter signal. Moreover, the vortex energy ratio under normal flow condition is greater than 80%, which can be adopted as an indicator to diagnose the state of a vortex flowmeter.

Gravel Accumulation in Deposits of Viscous Debris Flows with Hyper-concentration

According to the observational data of viscous debris flows with hyper-concentration, debris flows can be classified into three types:high-viscous, viscous, and sub-viscous debris flows.Distinct formation mechanism of different graded bedding structures in deposits of viscous debris flows was analyzed in this paper by using their yield-stress ratio and flow plug ratio.This paper specially analyzed the effect of Weissenberg which the gravels in squirm condition of hyper-concentration viscous flows would tend to move vertically, and the formation mechanism of the gravels accumulated at surface was also studied.The analysis in this paper can establish a foundation for the studies on differentiation of bedding structures of debris flow deposits and studies on dynamic parameters of debris flows.

Numerical Study on the Effects of Contraction Ratio in a Two-Phase Flow Injection Nozzle

The Euler-Euler numerical method was used to investigate the effects of contraction ratio on twophase flow mixing with mass transfer in the flow injection nozzle. The geometric shape of the nozzle was modified to improve carbonation efficiency. A gas inlet hole was created to increase the flow mixing of CO2 with water. A nozzle throat was also introduced to increase the gas dissolution by increasing flow rates. Various contraction ratios of nozzle throat, inlet gas and liquid velocities, and gas bubble sizes were employed to determine their effects on gas hold-up, gas concentration, and mass transfer coefficient. Results revealed that the flow injection nozzle with high contraction ratios improved carbonation because of high gas hold-up. Gas concentration was directly related to contraction ratio and gas flow velocities. Carbonation reduced when high liquid velocities and large gas bubbles were employed because of inefficient flow mixing. This study indicated that flow injection nozzle with large contraction ratios were suitable for carbonation because of their ability to increase gas hold-up, gas concentration, and mass transfer coefficient.

An online method to determine chlorine stable isotope composition by continuous flow isotope ratio mass spectrometry (CF-IRMS) coupled with a Gasbench Ⅱ

An online method using continuous flow isotope ratio mass spectrometry (CF-IRMS) interfaced with a Gasbench Ⅱ was presented to determine chlorine stable isotope composition. Silver chloride (AgCl) was quantitatively derived from chloride by using silver nitrate (AgNO3), and then was reacted with iodomethane (CH3I) to produce methyl chloride (CH3Cl). A GasBench Ⅱ equipped with a PoraPlot Q column was used to separate CH3Cl from any other gas species. Finally, chlorine stable isotope analysis was carried out on CH3Cl introduced to the IRMS in a helium stream via an active open split. The minimum amount of Cl used in this method is of the order of 1.4μmol. Inter-laboratory and inter-technique comparisons show that the total uncertainty incorporating both the precision and accuracy of this method is better than 0.007%. Furthermore, ten seawaters sampled from different locations have a narrow δ 37 Cl value range from -0.008% to 0.010%, with a mean value of (0.000±0.006)%. This supports the assumption that any seawater can be representative of standard mean ocean chloride (SMOC) and used as an international reference material.

Effects of aspect ratio on unsteady solutions through curved duct flow

The effects of the aspect ratio on unsteady solutions through the curved duct flow are studied numerically by a spectral based computational procedure with a temperature gradient between the vertical sidewalls for the Grashof number 100 ≤ Gr ≤ 2 000. The outer wall of the duct is heated while the inner wall is cooled and the top and bottom walls are adiabatic. In this paper, unsteady solutions are calculated by the time history analysis of the Nusselt number for the Dean numbers Dn = 100 and Dn = 500 and the aspect ratios 1≤γ≤ 3. Water is taken as a working fluid （Pr =7.0）. It is found that at Dn = 100, there appears a steady-state solution for small or large Gr. For moderate Gr, however, the steady-state solution turns into the periodic solution if γ is increased. For Dn = 500, on the other hand, it is analyzed that the steady-state solution turns into the chaotic solution for small and large Gr for any γ lying in the range. For moderate Gr at Dn = 500, however, the steady-state flow turns into the chaotic flow through the periodic oscillating flow if the aspect ratio is increased.

Fluid flow and heat transfer characteristics of spiral coiled tube: Effects of Reynolds number and curvature ratio

Numerical analysis was performed to investigate flow and heat transfer characteristics in spiral coiled tube heat exchanger. Radius of curvature of the spiral coiled tube was gradually increased as total rotating angle reached 12π. As the varying radius of curvature became a dominant flow parameter, three-dimensional flow analysis was performed to this flow together with different Reynolds numbers while constant wall heat flux condition was set in thermal field. From the analysis, centrifugal force due to curvature effect is found to have significant role in behavior of pressure drop and heat transfer. The centrifugal force enhances pressure drop and heat transfer to have generally higher values in the spiral coiled tube than those in the straight tube. Even then, friction factor and Nusselt number are found to follow the proportionality with square root of the Dean number. Individual effect of flow parameters of Reynolds number and curvature ratio was investigated and effect of Reynolds number is found to be stronger than that of curvature effect.

Zonal flow energy ratio evolution during L-H and H-L transitions in EAST plasmas

The essential role of zonal flow in the L-H transition and the suppression of turbulence have been studied with a long range correlation technique using Langmuir probe arrays in EAST tokamak.Two toroidally localized probe arrays are used to measure the zonal flow during L-H transition and H-L back transition.The energy ratio of the low frequency zonal flow to the total drift wave turbulence is calculated.During ELM-free H mode,the energy ratio is higher than that in L mode,which reveals the important role of zonal flows in regulating turbulence amplitude in L-H transition.

INFLUENCES OF THE FISH-MOUTH PROJECT AND THE GROINS ON THE FLOW AND SEDIMENT RATIO OF THE YANGTZE RIVER WATERWAY

A depth_integrated two_dimensional numerical model of current, salinity and sediment transport was proposed and calibrated by the observation data in the Yangtze River Estuary. It was then applied to investigate the flow and sediment ratio of the navigation channel, i.e. the North Channel of the Yangtze River Estuary,before and after the first phase waterway project is implemented. Particularly, the influences of groin length and the orientation of the submerged dam on the flow ratio and sediment load discharging into the North Channel were discussed. The numerical results demonstrate that less sediment load discharges into the navigation channel, which unburdens the waterway dredging, but in the meantime the flow ratio is also decreased. The flow and sediment ratio can be adjusted by changing layout and dimensions of the hydro_structures, such as the groin length, the top height, etc. The effect of the orientation of the submerged dam is more obvious than the groin lengh.

Augmentation of Heat Transfer in Pipe Flow Using Plain Twisted Tape Inserts for Different Twist Ratios

The heat transfer augmentation of plain twisted tape inserts for different twist ratios has been studied in this study. The data are conducted using the plain twisted tape insert with five different twist ratios respectively. The range of Reynolds number is considered under a uniform heat flux condition. In the case of simulation, the tapes are made from a stainless steel strip with a thickness of 2 mm. A tubular pipe with 850mm U-loop length and twist length of 800 mm each is considered in our study for simulation. Water is used as working fluids inside the tube for our simulation. The simulation results demonstrate that the important heat transfer parameters including Nusselt number (Nu), friction factor (f) and thermal performance index (η) are gradually increased with the increment of the twist ratio and reached at the saturated level while twist ratio is 3.5,?afterward the thermal properties are decreased.

Visual Study on Flow and Operational Characteristics of Flat Plate Closed Loop Pulsating Heat Pipes

This paper presents an experimental study including visualization on a flat plate closed loop pulsating heat pipes.It consists of a total of 40 channels with square cross section(2 mm×2 mm,165 mm long) machined directly on an aluminum plate(180 mm×120 mm×3 mm) covered by a transparent plate.The working fluid employed is ethanol.As a result,various flow patterns and their transitions are observed and found to be related to the fluid fill ratio,input heat load and the device orientation.Also the operational characteristics and working mechanism are discussed.

An Empirical Formula for Suspended Sediment Delivery Ratio of Main River after Confluence of Debris flow

In order to calculate the suspended sediment discharge of the flood debris flows into the main river,a small scale flume test was designed to simulate the process of confluence of Jiangjia Ravine and Xiangjiang River in Yunnan province,China.By test observation and data analysis,suspended sediment discharge of Debris flow after its entry into the main river was found to have a close relation with the bulk density,the confluence angle of the Debris flow and the main river,the ratio between per unit width discharge of Debris flow and main river.Based on the measured and simulated results,and statistical analysis,an empirical formula was proposed for the suspended SDR(Sediment Delivery Ratio) of the main river after the confluence of Debris flow.Compared with the observed results of Debris flow in 2009,the error between the data calculated by the empirical formula and the monitored data is only about 10%.

Impact of depth ratio on flow structure and turbulence characteristics of compound open channel flows

Compound open channel flows appear in most natural rivers are of great importance in river management and flood control.In this study,large eddy simulations were carried out to simulate the compound open channel flows with four different depth ratios(hr=0.10,0.25,0.50,and 0.75).The main flow velocity,secondary flow,Reynolds stress,and bed shear stress were obtained from numerical simulations.The depth-averaged stream wise momentum equation was used to quantify the lateral momentum exchange between the main channel and floodplain.The instantaneous coherent structures were presented by the Q criterion method.The impact of hr on flow structure and turbulence charac-teristics was analyzed.The results showed that with the increase of hr,the high velocity area in the main channel shifted to the floodplain,and the dip phenomenon became more obvious;the Reynolds stress largely contributed to the lateral momentum exchange within the flows near the side walls of floodplain;and the vortex structures were found to significantly increase in the floodplain region.