A Numerical Simulation of Air Flow in the Human Respiratory System Based on Lung Model

The lung is an important organ that takes part in the gas exchange process. In the study of gas transport and exchange in the human respiratory system, the complicated process of advection and diffusion (AD) in airways of human lungs is considered. The basis of a lumped parameter model or a transport equation is modeled during the inspiration process, when oxygen enters into the human lung channel. The quantitative measurements of oxygen are detached and the model equation is solved numerically by explicit finite difference schemes. Numerical simulations were made for natural breathing conditions or normal breathing conditions. The respiratory flow results for the resting conditions are found strongly dependent on the AD effect with some contribution of the unsteadiness effect. The contour of the flow rate region is labeled and AD effects are compared with the variation of small intervals of time for a constant velocity when breathing is interrupted for a negligible moment.

Impact of well placement and flow rate on production efficiency and stress field in the fractured geothermal reservoirs

Geothermal energy has gained wide attention as a renewable alternative for mitigating greenhouse gas emissions.The advancements in enhanced geothermal system technology have enabled the exploitation of previously inaccessible geothermal resources.However,the extraction of geothermal energy from deep reservoirs poses many challenges due to high‐temperature and high‐geostress conditions.These factors can significantly impact the surrounding rock and its fracture formation.A comprehensive understanding of the thermal–hydraulic–mechanical(THM)coupling effect is crucial to the safe and efficient exploitation of geothermal resources.This study presented a THM coupling numerical model for the geothermal reservoir of the Yangbajing geothermal system.This proposed model investigated the geothermal exploitation performance and the stress distribution within the reservoir under various combinations of geothermal wells and mass flow rates.The geothermal system performance was evaluated by the criteria of outlet temperature and geothermal productivity.The results indicate that the longer distance between wells can increase the outlet temperature of production wells and improve extraction efficiency in the short term.In contrast,the shorter distance between wells can reduce the heat exchange area and thus mitigate the impact on the reservoir stress.A larger mass flow rate is conducive to the production capacity enhancement of the geothermal system and,in turn causes a wider range of stress disturbance.These findings provide valuable insights into the optimization of geothermal energy extraction while considering reservoir safety and long‐term sustainability.This study deepens the understanding of the THM coupling effects in geothermal systems and provides an efficient and environmentally friendly strategy for a geothermal energy system.

A New Method for Measurement of Helium Mass Flow Rate in the Cryogenic System of TORE SUPRA

The TORE SUPRA Tokamak was built by EURATOM-CEA association. The NbTi conductor of superconducting coils is inserted in a tight enclosure filled with pressurized superfluid helium of 0.125 MPa at 1.8 K. The thick casing is cooled to 4.5 K by 1.8 MPa in 4.5 K supercritical helium circulation. Around this thick casing, a 80 K thermal shield protects the parts at very low temperatures from the thermal radiation, which is cooled by pressurized helium at 80 K and 1.8 MPa. A new measurement method for helium mass flow rate of 80 K shield and 4.5 K casing is described in this paper. The commissioning was done on the two helium loops of the cryoplant: the supercritical 4.5 K thick casing and 80 K shields. The purpose is to improve control of the 4.5 K and 80 K refrigeration loops.

Industrial Ecosystems and Food Webs＂ An Ecological-Based Mass Flow Analysis to Model the Progress of Steel Manufacturing in China

Materials and energy are transferred between natural and industrial systems, providing a standard that can be used to deduce the interactions between these systems, An examination of these flows is an essen- tial part of the conversation on how industry impacts the environment, We propose that biological sys- tems, which embody sustainability, provide methods and principles that can lead to more useful ways to organize industrial activity, Transposing these biological methods to steel manufacturing is manifested through an efficient use of available materials, waste reduction, and decreased energy demand with cur- rently available technology, In this paper, we use ecological metrics to examine the change in structure and flows of materials in the Chinese steel industry over time by means of a systems-based mass flow analysis, Utilizing available data, the results of our analysis indicate that the Chinese steel manufacturing industry has increased its efficiency and sustainable use of resources over time at the unit process level, However, the appropriate organization of the steel production ecosystem remains a work in progress, Our results suggest that through the intelligent placement of cooperative industries, which can utilize the waste generated from steel manufacturing, the future of the Chinese steel industry can better reflect ecosystem maturity and health while minimizing waste.

Experimental Study on the Mobility of Channelized Granular Mass Flow

Granular mass flows （e.g., debris flows/avalanches） in landslide-prone areas are of great concern because they often cause catastrophic disasters as a result of their long run-out distances and large impact forces. To investigate the factors influencing granular mass flow mobility, experimental tests were conducted in a flume model. Granular materials consisting of homogeneous sand and non- homogeneous sandy soil were used for studying particle size effects. Run-out tests with variable flow masses, water contents, and sloping channel confinement parameters were conducted as well. The results indicated that granular mass flow mobility was significantly influenced by the initial water content; a critical water content corresponding to the smallest flow mobility exists for different granular materials. An increase in the total flow mass generally induced a reduction in the travel angle （an increase in flow mobility）. Consistent with field observations, the travel angles for different granular materials decreased roughly in proportion to the logarithm of mass. The flume model tests illustrate that the measured travel angles increase as the proportion of fine particles increases. Interestingly, natural terrain possesses critical confinement characteristics for different granular mass flows.

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 1.4 μmol. 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 δ37Cl 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 fluid recirculation on mass transfer from the arterial surface to flowing blood

The effect of disturbed flow on the mass trans- fer from arterial surface to flowing blood was studied nu- merically, and the results were compared with that of our previous work. The arterial wall was assumed to be vis- coelastic and the blood was assumed to be incompressible and non-Newtonian fluid, which is more close to human arte- rial system. Numerical results indicated that the mass trans- fer from the arterial surface to flowing blood in regions of disturbed flow is positively related with the wall shear rates and it is significantly enhanced in regions of disturbed flow with a local minimum around the reattachment point which is higher than the average value of the downstream. There- fore, it may be implied that the accumulation of cholesterol or lipids within atheromatous plaques is not caused by the reduced efflux of cholesterol or lipids, but by the infiltration of the LDL （low-density lipoprotein） from the flowing blood to the arterial wall.

Design of fan beam optical sensor and its application in mass flow rate measurement of pneumatically conveyed solids

The fan-beam optical sensor is made up of many semiconductor lasers and detectors fixed around the wall alternately at a cross section of pneumatically conveying pipe. When the sensor works, a scanning light source emits a 50° lamellar fan-beam through the gas-solid two phase flow, and the projection data resulting extinction effect of solid particles are detected at the same time. With the projection data, the flow rate mass can be calculated, and then the flow image can be reconstructed. In this paper, the design of the sensor including spatial arrangement of the structural parts, basic principle and measurement sensitivity distribution are introduced. The mathematical measurement model of solid mass flow rate is presented together with the testing results.

Comprehensive interpretation of the Sedongpu glacier-related mass flows in the eastern Himalayan syntaxis

Glacier-related mass flows(GMFs)in the high-mountain cryosphere have become more frequent in the last decade,e.g.,the 2018 Sedongpu(SDP)GMFs in the Himalayas.Seismic forcing,thermal perturbation and heavy rainfall are common triggers of the GMFs.But the exact role of seimic forcing in the GMF formation is poorly known due to scarity of observational data of real cases.Here the evolution processes of the GMFs and the detachment of the trunk glacier in SDP are reconstructed by using remote sensing techniques,including feature-tracking of multi-source optical satellite imagery and visual interpretation.The reconstruction demonstrates that the high frequency of GMF events in SDP after the Milin earthquake on 18 November 2017 was mainly attributed to the earthquake-induced glacial stress changes and destablisation.The post-earthquake velocity of the trunk glacier is about three times of that in December 2016 and December 2017.The median glacier-surface velocity raised to 0.32 m d-1between November 2017 and June 2018,being 14%-77%higher than that of pre-earthquake,which is initiated by the seismic forcing and then aggravated by additional loading of ice/rock avalanches,infiltration of liquid water,progressively crevassed glacier,and local compressional deformation.Ensuing surge motion of the trunk glacier resulted from high temperature and heavy precipitation between July and September 2018.We infer that the trunk glacier is more sensitive to the thermal perturbation after the Milin earthquake,which is the predominant cause in sudden surge movement.These findings reveal comprehensive mechanisms of quakeinduced,low-angle,glacial detachment and multisource-driven GMF in the Himalayas.

Lumped Parameter Mass Flow Rate and Pressure Control Characteristics Model for High-Speed Pneumatic PWM on/off Valve

Aiming at solving the problem of strong coupling characteristic of the key parameters of high-speed pneumatic pulse width modulation( PWM) on / off valve, a general lumped parameter mathematical model based on the valves time periods was well developed. With this model,the mass flow rate and dynamic pressure characteristics of constant volumes controlled by high-speed pneumatic PWM on /off valves was well described. A variable flow rate coefficient model was proposed to substitute for the constant one used in most of the prior works to investigate PWM on /off valves' dynamical pressure response, and a formula for disclosing the inherent relationship among the PWM command signal,static mass flow rate,and sonic conductance of the valve was newly derived.Finally,an extensive set of analytical experimental comparisons were implemented to verify the validity of the proposed mathematica model. With the proposed model, PWM on /off valves' characteristics,such as mass flow rate,step pressure response of the valve control system,mean pressure and ripple amplitude,not only in the linear range,but also in the nonlinear range can be wel predicted; Good agreement between measured and calculated results was obtained,which proved that the model is helpful for designing a control strategy in a closed loop control system.

Experimental Analysis of the Flow Characteristics of an Adjustable Critical-Flow Venturi Nozzle

The response of an adjustable critical-flow Venturi nozzle is investigated through a set indoor experiments aimed to determine the related critical flow rate,critical pressure ratio,and discharge coefficient.The effect of a variation in the cone displacement and liquid content on the critical flow characteristics is examined in detail and it is shown that the former can be used to effectively adjust the critical flow rate.The critical pressure ratio of the considered nozzle is above 0.85,and the critical flow control deviation of the gas flow is within±3%.Liquid flow can reduce the gas critical mass flow rate accordingly,especially for the cases with larger liquid volume and lower inlet pressure.The set of results and conclusions provided are intended to support the optimization of steam injection techniques in the context of heavy oil recovery processes.

隧道火灾相向射流排烟系统烟气质量流率比例系数

为探究隧道相向射流排烟系统中火灾发生时烟气的流动特性,通过FDS数值模拟研究隧道内不同上、下游风速工况下的上、下游烟气质量流率变化。基于等效风速、理论分析和数值模拟结果得到上、下游风速与烟气质量流率比例系数的关系式。结果表明:当等效风速小于临界风速时,上、下游烟气质量流率比值和烟气质量流率比例系数随等效风速增加而减小,并且等效风速与上、下游烟气质量流率比值存在线性关系;当等效风速大于临界风速时,上、下游烟气质量流率比值和烟气质量流率比例系数为0。

ITER气体注入系统注入管线和气体流量控制阀特性研究

为验证国际热核聚变实验堆计划(ITER)的气体注入系统(GIS)的设计是否能够满足装置运行的要求,以及为优化气体注入系统的气体加料控制模式提供直接而可靠的数据支撑。该研究在基于ITER GIS最终设计阶段提供的设计方案的基础上,在模拟实验平台上进行实验研究,该研究涉及燃料气体H2、D2以及杂质气体Ne、Ar、N2及其混合气体的注入特性,包括其供气压力、注入管线结构对响应时间的影响。实验结论证明,气体注入系统的设计可以满足ITER装置的运行要求,且实验数据为ITER装置的气体控制模式,尤其是实现杂质气体快速、精确的控制,从而保障ITER装置安全运行,提供有力的技术支持。

基于可调文氏管的液氧流量闭环控制特性研究

针对液氧供应系统流量精准控制困难的问题,开发了一套流量闭环控制系统并应用于液氧供应系统中。为实现系统按预设目标流量进行输出,进行了四类试验:无控制试验、流量闭环控制试验、PID参数影响试验与流量阶跃调节试验,研究了贮箱压力、液氧温度、针锥位置、调节范围与PID参数等因素对液氧流量闭环控制特性的影响。结果表明,通过反馈实时测得的液氧质量流量,流量闭环控制系统控制可调文氏管节流面积变化,实现了液氧流量±1%的精准控制,解决了由于系统压力波动及液氧温度变化等原因导致的液氧流量供应不稳定的问题,并实现了液氧在5∶1流量变比内的精准阶跃调节。

基于NSGA-Ⅱ算法的含汞天然气脱水脱烃单元工艺参数优化

在含汞天然气的脱水脱烃处理过程中,部分汞会进入外输干气。为降低外输干气中汞的质量流量并考虑系统能耗,利用HYSYS软件模拟了高含汞天然气脱水脱烃单元,探究低温分离器进料温度、乙二醇质量分数、乙二醇质量流量对外输干气中汞质量流量以及系统能耗的影响。在此基础上,依据响应面法建立各关键参数与外输干气中汞质量流量以及系统能耗的多目标优化模型,并使用NSGA-Ⅱ(非支配排序遗传算法Ⅱ)进行多目标寻优。结果表明:经过NSGA-Ⅱ算法计算出的Pareto解值与HYSYS模拟值误差小于1%,其结果精确度较高。且经优化后的外输干气中汞的质量流量以及系统能耗均有所下降,故可利用NSGA-Ⅱ算法求解得到的Pareto解集可为天然气脱水脱烃流程的参数优化提供指导。

Flow Simulation of a Horizontal Well with Two Types of Completions in the Frame of a Wellbore–Annulus–Reservoir Model

Well completions are generally used to connect a reservoir to the surface so that fluids can be produced from orinjected into it. With these systems, pipe flows are typically established in the horizontal sections of slotted screencompletions and inflow control device (ICD) completions;moreover, an annular flow exists in the region betweenthe pipe and the borehole wall. On the basis of the principles of mass and momentum conservation, in the presentstudy, a coupling model considering the variable mass flow of the central tubing, the variable mass flow of theannular tubing and the reservoir seepage is implemented to simulate the wellbore–annulus–reservoir behaviorin the horizontal section of slotted-screen and ICD completions. In earlier models, only the central tubing variablemass flow and reservoir seepage flow were considered. The present results show that the closer the heel end, thegreater is the flow per unit length in the central tubing from the annulus. When external casing packers are notconsidered, the predicted production rate of the slotted screen completion, which is obtained using the variablemass flow model not taking into account the annulus flow, is 9.51% higher than the rate obtained using the (complete) model with annulus flow. In addition, the incomplete model forecasts the production of ICD completion ata 70.98% higher rate. Both models show that the pressure profile and flow profile of the borehole wall are relatively uniform in the wellbore–annulus–reservoir in horizontal wells.

Experiments on an Open-Loop Cycle Carbon Dioxide Refrigeration System

An open loop cycle carbon dioxide(CO2)refrigeration system is established,and the cooling performances of high-pressure CO2 under different storage conditions(25℃,30℃,and 35℃)are investigated.Moreover,the experimental mass flow rates of CO2 are compared with the theoretical values at different conditions and refrigeration capacities.The results indicate that the storage condition of CO2 has a significant impact on the refrigeration performance,and the mass flow rate of CO2 increases with the increasing storage temperature in a given refrigeration capacity.

Mass transport deposits and processes in the north slope of the Xisha Trough,northern South China Sea

Triple mass-transport deposits （MTDs） with areas of 625, 494 and 902 km^2, respectively, have been identified on the north slope of the Xisha Trough, northern South China Sea margin. Based on high-resolution seismic reflection data and multi-beam bathymetric data, the Quaternary MTDs are characterized by typical geometric shapes and internal structures. Results of slope analysis showed that they are developed in a steep slope ranging from 5° to 35°. The head wall scarps of the MTDs arrived to 50 km in length （from headwall to termination）. Their inner structures include well developed basal shear surface, growth faults, stepping lateral scarps, erosion grooves, and frontal thrust deformation. From seismic images, the central deepwater channel system of the Xisha Trough has been filled by interbedded channel-levee deposits and thick MTDs. Therefore, we inferred that the MTDs in the deepwater channel system could be dominated by far-travelled slope failure deposits even though there are local collapses of the trough walls. And then, we drew the two-dimensional process model and three- dimensional structure model diagram af the MTDs. Combined with the regional geological setting and previous studies, we discussed the trigger mechanisms of the triple MTDs.

Theoretical and Experimental Investigations of Solar Heating Systems at Specified Output Conditions of Hot Water

The theoretical analysis discussed in this work is a suitable mathematical tool by which the performance of the proposed collector can be predicted. The obtained experimental results coincide with the obtained theoretical data obtained from the devised computer program. Controlled output temperature can be obtained from the proposed system. The performance of the tested collector under the proposed intermittent flow conditions overcomes that of the conventional thermosyphone flow collector.