Aluminum X-ray mass-ablation rate measurements

Measurements of the mass ablation rate of aluminum(Al)have been completed at the Omega Laser Facility.These measurements show that the mass-ablation rate of Al is higher than plastic(CH),comparable to high density carbon(HDC),and lower than beryllium.The mass-ablation rate is consistent with predictions using a 1D Lagrangian code,Helios.The results suggest Al capsules have a reasonable ablation pressure even with a higher albedo than beryllium or carbon ablators and further investigation into the viability of Al capsules for ignition should be pursued.

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.

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.

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.

Rock Mass Quality Rating Based on the Multi-Criteria Grey Metric Space

Assessment of rock mass quality significantly impacts the design and construction of underground and open-pit mines from the point of stability and economy.This study develops the novel Gromov-Hausdorff distance for rock quality(GHDQR)methodology for rock mass quality rating based on multi-criteria grey metric space.It usually presents the quality of surrounding rock by classes(metric spaces)with specified properties and adequate interval-grey numbers.Measuring the distance between surrounding rock sample characteristics and existing classes represents the core of this study.The Gromov-Hausdorff distance is an especially useful discriminant function,i.e.,a classifier to calculate these distances,and assess the quality of the surrounding rock.The efficiency of the developed methodology is analyzed using the Mean Absolute Percentage Error(MAPE)technique.Seven existing methods,such as the Gaussian cloud method,Discriminant method,Mutation series method,Artificial neural network(ANN),Support vector machine(SVM),Grey wolf optimizer and Support vector classification method(GWO-SVC)and Rock mass rating method(RMR)are used for comparison with the proposed GHDQR method.The share of the highly accurate category of 85.71%clearly indicates compliance with actual values obtained by the compared methods.The results of comparisons showed that the model enables objective,efficient,and reliable assessment of rock mass quality.

Crustal Growth Rate of the North China Platform:a Method of Estimating Mass Equilibrium between Crust and Mantle

The following equation is proposed in this paper to estimate the crustal growth rate of the North China Platform on the basis of mass equilibrium between the crust and the mantle:The results indicate that the mass fractions of the crust during different geological periods are close to the real mass fractions of the crust in the upper mantle and the whole mantle (2-2.5% and 0.5 -0.6%, respectively, Hofmann, 1986), and the discrepancy of the results is probably related to that the heterogeneous contribution of the mantle to the crust both in space and in element. The results also show that the mass of the Archaean crust is only half that of the Proterozoic crust, and the crustal mass remained unchanged from Proterozoic to Paleozoic. suggesting that the plate movement at least started from the Late Proterozoic.

MASS FLOW RATE INDUCED BY COMBINED ROOF SOLAR COLLECTOR AND VERTICAL STACK IN A HOT HUMID CLIMATE

This paper presents the investigation of solar induced ventilation that utilizes roof solar collector and vertical stack. Three prototypes, namely A, B and C, were developed based on preliminary experimental work. They were then used in simulation study with the objective of determining the prototype that was able to induce the highest mass flow rate. The validation of simulation modelling against experiment indicated a good agreement between these two results. The findings showed that prototype A induced the highest mass flow rate. However, prototype C, which had obstructions at the stack outlets, was more appropriate for application in Malaysia due to various prevailing wind directions. In addition, the findings also indicated that besides solar radiation, the mass flow rate induced by the prototypes was also influenced by the local wind direction, the inlet and outlet positions as well as the outlet design. In summary, the findings highlighted the potential application of the proposed solar induced ventilation in a hot and humid climate.

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.

Sweat Rate and Electrolyte Composition in Young Women of Varying Body Mass Indices during Moderate Exercise

Sweat is a hypotonic fluid excreted by sweat glands to cool the body. There are conflicting reports on whether or not body composition has an effect on thermoregulatory responses especially during exercise. This study was aimed at determining and comparing sweat rate and electrolyte composition in underweight (BMI BMI 30 kg/m2) during moderate exercise. Forty women (19 - 25 years) were used during this study after assessing their health status. They were stratified for BMI with each group having a total of ten women. It was ensured that all the women used in the study were euhydrated before commencing the research. Before sweat collection, the treadmill was calibrated according to the Bruce Treadmill Protocol. Sweat samples were obtained with a sweat suction apparatus from a 120 cm2 circular area marked on the skin of the face and neck, after a 15 minute fast walk on a treadmill at an inclination of 15° and at a speed of 4.2 km/h at 27°C room temperature. The time at which sweating commenced in the subjects was recorded. Sweat rate (L/hour) was calculated using the formula: sweat rate (L/hr) = (pre-exercise body weight - Post-exercise body weight)/exercise duration. Each sweat sample was collected and analysed immediately. The results showed that obese women had a significantly (P < 0.05) higher sweat rate and underweight women had a significantly (P < 0.05) lower sweat rate than all the other groups. Furthermore, subjects with a high body surface area showed significantly higher sweat rates compared to subjects with lower body surface area. Sweat electrolyte composition did not change in all BMI groups. In conclusion, obese subjects are more likely to develop fluid imbalances than underweight and normal weight subjects during moderate exercise. Also, underweight women might be at a thermoregulatory disadvantage because of their reduced body fat and body surface area.

Classification and assessment of rock mass parameters in Choghart iron mine using P-wave velocity

Engineering rock mass classification,based on empirical relations between rock mass parameters and engineering applications,is commonly used in rock engineering and forms the basis for designing rock structures.The basic data required may be obtained from visual observation and laboratory or field tests.However,owing to the discontinuous and variable nature of rock masses,it is difficult for rock engineers to directly obtain the specific design parameters needed.As an alternative,the use of geophysical methods in geomechanics such as seismography may largely address this problem.In this study,25 seismic profiles with the total length of 543 m have been scanned to determine the geomechanical properties of the rock mass in blocks Ⅰ,Ⅲ and Ⅳ-2 of the Choghart iron mine.Moreover,rock joint measurements and sampling for laboratory tests were conducted.The results show that the rock mass rating（RMR） and Q values have a close relation with P-wave velocity parameters,including P-wave velocity in field(V;).P-wave velocity in the laboratory(V;) and the ratio of V;V;(i.e.K;= V;/V;.However,Q value,totally,has greater correlation coefficient and less error than the RMR,In addition,rock mass parameters including rock quality designation（RQD）,uniaxial compressive strength（UCS）,joint roughness coefficient（JRC） and Schmidt number（RN） show close relationship with P-wave velocity.An equation based on these parameters was obtained to estimate the P-wave velocity in the rock mass with a correlation coefficient of 91%.The velocities in two orthogonal directions and the results of joint study show that the wave velocity anisotropy in rock mass may be used as an efficient tool to assess the strong and weak directions in rock mass.

Application of rock mass classification systems to rock slope stability assessment:A case study

The stability of rock slopes is considered crucial to public safety in highways passing through rock cuts, as well as to personnel and equipment safety in open pit mines. Slope instability and failures occur due to many factors such as adverse slope geometries, geological discontinuities, weak or weathered slope materials as well as severe weather conditions. External loads like heavy precipitation and seismicity could play a significant role in slope failure. In this paper, several rock mass classification systems developed for rock slope stability assessment are evaluated against known rock slope conditions in a region of Saudi Arabia, where slopes located in rugged terrains with complex geometry serve as highway road cuts. Selected empirical methods have been applied to 22 rock cuts that are selected based on their failure mechanisms and slope materials. The stability conditions are identified, and the results of each rock slope classification system are compared. The paper also highlights the limitations of the empirical classification methods used in the study and proposes future research directions.

Modification of rock mass rating system:Interbedding of strong and weak rock layers

Rock mass classification systems are the very important part for underground projects and rock mass rating(RMR) is one of the most commonly applied classification systems in numerous civil and mining projects. The type of rock mass consisting of an interbedding of strong and weak layers poses difficulties and uncertainties for determining the RMR. For this, the present paper uses the concept of rock bolt supporting factor(RSF) for modification of RMR system to be used in such rock mass types. The proposed method also demonstrates the importance of rock bolting practice in such rock masses. The geological parameters of the Shemshak Formation of the Alborz Tunnel in Iran are used as case examples for development of the theoretical approach.

Effect of mixing rate and temperature on primary Si phase of hypereutectic Al-20Si alloy during control ed diffusion solidification(CDS) process

Controlled Diffusion Solidification(CDS) is a promising process relied on mixing two liquid alloys of precisely controlled chemistry and temperature in order to produce a predetermined alloy composition. In this study, the CDS was employed to prepare hypereutectic Al-20%Si(mass fraction) alloy using Al-30%Si and pure Al of different temperatures. The mixing rate was controlled using three small crucibles with a hole of different diameters in their bottom. The effect of mixing rate and temperature on the microstructure of the primary Si-phase during the mixing of molten Al and Al-30%Si was studied. The results showed that when the diameter of the small crucible bottom hole is 16 mm, a higher mass mixing rate 0.217 kg·s-1 would results in a lower stream velocity 0.414 m·s-1. Conversely a lower mass mixing rate 0.114 kg·s-1(the diameter of the small crucible bottom hole is 8 mm) would result in a higher fluid stream velocity 0.879 m·s-1. A lower mass mixing rate would be better to refine the primary Si than a higher mass mixing rate. Meanwhile, the morphology and distribution of primary Si could also be improved. Especially, when Al-30%Si alloy at 820 °C was mixed with pure Al at 670 °C in the case of a mass mixing rate of 0.114 kg·s-1 and a pouring temperature of 680 °C, the average size of the primary Si phase would be only 18.2 μm. Its morphology would mostly be octahedral and the primary Si would distribute uniformly in the matrix microstructure. The lower mass mixing rate(0.114 kg·s-1) will enhance the broken tendency of Al-30%Si steam and the mixing agitation of resultant melt, so the primary Si phase can be better refined.

热电池FeS_(2)-CoS_(2)复合正极材料利用率的影响因素

采用高能球磨和磁悬浮筛分法制备了不同粒径的FeS_(2)-CoS_(2)复合正极材料,并通过单体电池放电试验研究了LiB/LiCl-LiBr-KBr/FeS_(2)-CoS_(2)热电池中正极材料粒径、正负极质量比和放电温度对正极材料利用率的影响。结果表明:在450℃条件下,当FeS_(2)粒径为7.85~59.12μm时,正极材料利用率随FeS_(2)粒径的减小而增大;当FeS_(2)粒径为3.30~7.85μm时,正极材料利用率随FeS_(2)粒径的减小而减小。FeS_(2)(7.85μm)-CoS_(2)(8.06μm)复合正极单体电池的放电性能最佳,截止电压1.5 V时,其放电比容量为342.4 mA·h·g^(-1),正极材料利用率为48.8%。随着单体电池工作时间的延长,其放电比容量随正负极质量比的减小而增大,在正负极质量比为1.67时,450℃条件下的FeS_(2)-CoS_(2)复合正极单体电池的放电比容量高于400℃和500℃,截止电压1.5 V时,其放电比容量为389.2 mA·h·g-1,正极材料利用率高达55.5%。

Mass Transfer During Osmotic Dehydration Using Acoustic Cavitation

An experimental study on intensifying osmotic dehydration was carried out ina state of nature and with acoustic cavitation of different cavitating intensity (0.5A, 0.7A and0.9A) respectively, in which the material is apple slice of 5mm thickness. The result showed thatacoustic cavitation remarkably enhanced the osmotic dehydration, and the water loss was acceleratedwith the increase of cavitating intensity. The water diffusivity coefficients ranged from1.8x10^(-10)m^2·s^(-1) at 0.5A to 2.6x10^(-10)m^2·s^(-1) at 0.9A, and solute diffusivitycoefficients ranged from 3.5x10^(-11) m^2·s^(-1) at 0.5A to 4.6X10^(-11)m^2·s^(-1) at 0.9A. On thebasis of experiments, a mathematical model was established about mass transfer during osmoticdehydration, and the numerical simulation was carried out. The calculated results agree well withexperimental data, and represent the rule of mass transfer during osmotic dehydration intensified byacoustic cavitation.

Slope mass rating and kinematic analysis of slopes along the national highway-58 near Jonk, Rishikesh, India

The ro ad n etw o rk in th e H im alayan terrain , connecting re m o te areas e ith e r in th e valleys o r on th e hillslopes, plays a pivotal role in socio-econom ic d e v elo p m en t ofIn d ia. The planning, d ev elo p m en t an d evenm ain ten an ce o f ro ad an d rail netw o rk s in such precarious terrain s are alw ays a challenging task becauseo f com plexities p osed by topography, geological stru ctu res, varied lithology an d neotectonics. Increasingp o p u latio n an d c o n stru ctio n o f roads have led to destab ilisatio n o f slopes, th u s leading to m ass w astingand m ovem ent, fu rth e r aggravation d u e to recen t events o f cloud bu rsts and u n p re c e d e n te d flash floods.V ulnerability analysis o f slopes is an im p o rta n t co m p o n e n t for th e ＂Landslide H azard A ssessm ent＂ and＂Slope Mass C h aracterisation＂ guide p lan n ers to p red ict an d choose suitable w ays for c o n stru ctio n ofroads and o th e r en g in eerin g stru ctu res. The pro b lem o f landslides along th e n ational highw ay-58 （NH-58） from Rishikesh to D evprayag is a co m m o n scene. The slopes along th e NH-58 b e tw e e n Jonk andRishikesh w ere investigated, w h ich experienced v ery heavy traffic especially from M arch to A ugust dueto pilgrim age to K edarnath shrine. On th e basis o f slope m ass rating （SMR） investigation, th e area falls instable class, an d landslide susceptibility score （LSS） values also indicate th a t th e slopes u n d e r investigationfall in low to m o d erate v ulnerability to landslide. More atte n tio n s should be paid to th e slopes toachieve g reater safe an d econom ic b enefits along th e highw ay.

Performance analysis of empirical models for predicting rock mass deformation modulus using regression and Bayesian methods

Deformation modulus of rock mass is one of the input parameters to most rock engineering designs and constructions.The field tests for determination of deformation modulus are cumbersome,expensive and time-consuming.This has prompted the development of various regression equations to estimate deformation modulus from results of rock mass classifications,with rock mass rating(RMR)being one of the frequently used classifications.The regression equations are of different types ranging from linear to nonlinear functions like power and exponential.Bayesian method has recently been developed to incorporate regression equations into a Bayesian framework to provide better estimates of geotechnical properties.The question of whether Bayesian method improves the estimation of geotechnical properties in all circumstances remains open.Therefore,a comparative study was conducted to assess the performances of regression and Bayesian methods when they are used to characterize deformation modulus from the same set of RMR data obtained from two project sites.The study also investigated the performance of different types of regression equations in estimation of the deformation modulus.Statistics,probability distributions and prediction indicators were used to assess the performances of regression and Bayesian methods and different types of regression equations.It was found that power and exponential types of regression equations provide a better estimate than linear regression equations.In addition,it was discovered that the ability of the Bayesian method to provide better estimates of deformation modulus than regression method depends on the quality and quantity of input data as well as the type of the regression equation.

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.

3D porous V2O5 architectures for high-rate lithium storage

The discovery of novel electrode materials promises to unleash a number of technological advances in lithium-ion batteries.V2O5 is recognized as a high-performance cathode that capitalizes on the rich redox chemistry of vanadium to store lithium.To unlock the full potential of V2O5,nanotechnology solution and rational electrode design are used to imbue V2O5 with high energy and power density by addressing some of their intrinsic disadvantages in macroscopic crystal form.Here,we demonstrate a facile and environmental-friendly method to prepare nanorods-constructed 3D porous V2O5 architectures(3 D-V2O5)in large-scale.The 3D porous architecture is found to be responsible for the enhanced charge transfer kinetics and Li-ion diffusion rate of the 3D-V2O5 electrode.As the result,the 3D-V2O5 surpasses the conventional bulk V2O5 by showing enhanced discharge capacity and rate capability(delivering 154 and 127 m Ah g^-1 at 15 and 20 C,respectively).

Research on unloading nonlinear mechanical characteristics of jointed rock masses

Geological environments of rock mass projects are always very complicated, and further investigations on rock mechanical characteristics are needed. There are considerable distinctions in rock mechanical characteristics under unloading and loading conditions. A series of tests are conducted to study the stress-strain relationship of rock masses under loading and unloading conditions. Also, the anisotropy, the size effect, and the rheological property of unloading rock mass are investigated. The tests presented in the paper include model test and granite rheological test, which are conducted considering geological condition, rock mass structure, in-situ stress field of the permanent shiplock of the Three Gorges Project. The main differences between loading and unloading rock masses are stress paths, yield criteria, deformation and strength parameters, etc.. Different structural plane directions affect unloading rock mass evidently. With increasing size, the tensile strength, the compressive strength, the deformation modulus, the Poisson’s ratio and the anisotropy of rock mass all decrease. For sandstone samples with parallel bedding planes, the cohesion c increases but the internal friction angle ? decreases under unloading condition when compared with the values under loading condition. While for samples with vertical bedding planes, the trend is adverse. The rheological property of rocks has close relationship with the tensile stresses of rock masses. When the sandstone samples are tested under high stress condition, their rheological properties are very obvious with the unloading of confining pressure, and three typical rheological stages are shown. Rheological rate changes with the variations in axial stress and confining pressure.