Solid Rotation Research Articles

Dipolar Energy as an Electrical Power Source: Dipole Rotation in Solids Enables a New Source for the Triboelectric Generator

Herein, the concept of triboelectric generators using dipolar polarization energy as an electrical power source is introduced. Dipolar polarization energy is stored in dielectric films by rubbing, and is conveyed to external circuits for use during the depolarization process. Pyromellitic dianhydride‐4,4’‐oxydianiline polyimide films are used as a possible candidate for triboelectric generators, where polarization is formed by rubbing owing to the orientational alignment of polar molecular groups. The current–voltage measurements are used to evaluate the equivalent‐circuit parameters of the generator. The current source is 0.07 nA at 30 °C, which is enhanced to 0.13 nA at 110 °C. It is indicated in these results that the depolarization process proceeds in a short time at higher temperatures, causing an increase in the current. Consequently, the maximum power increases from 18 nW (30 °C) to 33 nW (110 °C). The enhancement of the output power at higher temperatures well supports the idea of using dipolar polarization energy as a power source of triboelectric generators.

Doppler wind measurements in Neptune’s stratosphere with ALMA

Context. Neptune’s tropospheric winds are among the most intense in the Solar System, but the dynamical mechanisms that produce them are still unclear. Measuring wind speeds at different pressure levels may help shed light on the atmospheric dynamics of the planet. Aims. The goal of this work is to directly measure winds in Neptune’s stratosphere with ALMA Doppler spectroscopy. Methods. We derived the Doppler lineshift maps of Neptune at the CO(3-2) and HCN(4-3) lines at 345.8 GHz (λ ∼ 0.87 mm) and 354.5 GHz (0.85 mm), respectively. For that purpose, we used spectra obtained with ALMA in 2016 and recorded with a spatial resolution of ∼0.37″ on Neptune’s 2.24″ disk. After subtracting the planet’s solid rotation, we inferred the contribution of zonal winds to the measured Doppler lineshifts at the CO and HCN lines. We developed an MCMC-based retrieval methodology to constrain the latitudinal distribution of wind speeds. Results. We find that CO(3-2) and HCN(4-3) lines probe the stratosphere of Neptune at pressures of 2−1.8+12 mbar and 0.4−0.3+0.5 mbar, respectively. The zonal winds at these altitudes are less intense than the tropospheric winds based on cloud tracking from Voyager observations. We find equatorial retrograde (westward) winds of −180−60+70 m s−1 for CO, and −190−70+90 m s−1 for HCN. Wind intensity decreases towards mid-latitudes and wind speeds at 40°S are −90−60+50 m s−1 for CO and −40−80+60 m s−1 for HCN. Wind speeds become 0 m s−1 at about 50°S. We find that the circulation reverses to a prograde jet southwards of 60°S. Overall, our direct stratospheric wind measurements match previous estimates from stellar occultation profiles and expectations based on thermal wind equilibrium. Conclusions. These are the first direct Doppler wind measurements performed on the Icy Giants, opening up a new method for the study and monitoring of their stratospheric dynamics.

Absolute Paleolatitude of Northern Zealandia From the Middle Eocene to the Early Miocene

AbstractThe absolute position during the Cenozoic of northern Zealandia, a continent that lies more than 90% submerged in the southwest Pacific Ocean, is inferred from global plate motion models, because local paleomagnetic constraints are virtually absent. We present new paleolatitude constraints using paleomagnetic data from International Ocean Discovery Program Site U1507 on northern Zealandia and Site U1511 drilled in the adjacent Tasman Sea Basin. After correcting for inclination shallowing, five paleolatitude estimates provide a trajectory of northern Zealandia past position from the middle Eocene to the early Miocene, spanning geomagnetic polarity chrons C21n to C5Er (∼48–18 Ma). The paleolatitude estimates support previous works on global absolute plate motion where northern Zealandia migrated 6° northward between the early Oligocene and early Miocene, but with lower absolute paleolatitudes, particularly in the Bartonian and Priabonian (C18n–C13r). True polar wander (solid Earth rotation with respect to the spin axis), which only can be resolved using paleomagnetic data, may explain the discrepancy. This new paleomagnetic information anchors past latitudes of Zealandia to Earth's spin axis, with implications not only for global geodynamics, but also for addressing paleoceanographic and paleoclimate problems, which generally require precise paleolatitude placement of proxy data.

Enhanced enzymatic hydrolysis of corn stover using twin‐screw extrusion under mild conditions

AbstractThis paper aims to investigate the effect of extrusion at high solid loading on corn stover (CS) properties and its enzymatic hydrolysis. This biomass was extruded under different screw speeds and different solid loadings and the impact of these parameters on the physicochemical properties was evaluated. It was found that lignocellulosic components were not significantly affected by the pretreatment, while the surface area increased with solid loading and rotation speed. Different enzyme cocktails were used for the enzymatic hydrolysis of extruded and untreated CS. Overall, mild twin‐extrusion enhanced the enzymatic hydrolysis of CS through an increase in glucose and xylose yields by 134–212% and 214–294%, respectively, when using Trichoderma longibrachiatum cellulase. The highest sugar content was obtained from CS extruded under 400 g total solids per liter and 200 rpm. The energy efficiency of the pretreatment was also assessed and was found to be maximal at 400 g total solids per liter and 200 rpm. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd.

Improving resident education on the inpatient solid tumor oncology rotation through development of an asynchronous video curriculum.

e23014 Background: As the oncology patient population grows, continued recruitment of talented individuals is essential. Meaningful and highly educational clinical exposures play a crucial role in a resident’s decision to pursue fellowship in oncology. Currently, the majority of oncology exposure occurs in the inpatient setting, where trainees are confronted with many competing clinical demands, leaving minimal time for teaching. Prior work has demonstrated that dedicated time for teaching supplemented with high-yield educational material improves trainee satisfaction and interest in a particular field. We hypothesize that implementing an asynchronous inpatient video oncology curriculum will improve resident clinical competency and satisfaction. Methods: This is an ongoing, single institution educational intervention using the Kern method for curriculum development in the Johns Hopkins Osler Internal Medicine Residency (IRB00307077). A targeted needs assessment has been developed to identify gaps in medical knowledge, assess preparedness in managing common solid tumor inpatient diagnoses, and explore satisfaction with prior educational experiences on this service. Based on these results, ten educational videos will be created by content experts and aligned with the learning objectives of the Osler residency program and ABIM blueprint. Trainees will have dedicated time to watch the videos during their solid tumor rotation. We plan to evaluate effectiveness of our curriculum by measuring completion rates and pre- and post-video multiple choice responses. We will also assess knowledge retention and resident satisfaction at three and six months post-rotation with online questionnaires. Results: Annual Osler program ACGME survey data review revealed a high level of resident dissatisfaction with the oncology clinical experience compared with other rotations. While 83.3% of residents rated their general internal medicine experience as “excellent,” only 52.4% rated their oncology experience as “excellent.” Needs assessment data collection has been delayed by the COVID-19 pandemic but is ongoing. Following topic selection, videos will be created in April 2022 with plans for video curriculum implementation in July 2022. Conclusions: In order to attract and retain trainees in the field of oncology, it is imperative that educational curricula adapts to meet learners’ needs. Efficient, evidence-based instructional strategies designed to promote clinical competency for internal medicine residents on an inpatient solid tumor service may foster engagement and rotation satisfaction. We are currently evaluating how an asynchronous video inpatient oncology curriculum may significantly improve the inpatient internal medicine trainee experience. If successful, this curriculum can be adapted for other trainees and practitioners new to the field of oncology.

Theoretical modeling of a vortex-type liquid metal MHD generator for energy harvesting applications

The use of liquid metals (LM) in energy harvesting is gaining attention due to their unique properties. The DC vortex magnetohydrodynamic (MHD) generator is a suitable and robust option among the different approaches in which LM can be used for energy scavenging. In this device, the LM is driven in a cylindrical chamber to produce a swirling flow, which interacts with an external magnetic field, inducing electric currents that can be extracted to power an external electric system. In turn, the electrical resistance of this system highly affects the dynamics of the flow and the electric variables. In this work, two analytical models for the total voltage, electric current, electric and fluid power are developed. One model considers an inviscid fluid performing a rigid solid rotation. The second model considers a real fluid, for which the velocity distribution is also determined. For this latter case, MHD induced effects are modeled. These solutions are also obtained in dimensionless form in terms of the interaction parameter, Reynolds number and Hartmann number. In addition, 2D and 3D numerical models were implemented. These models are compared with reported experimental results, obtaining a good qualitative and quantitative agreement (differences ⩽13.5%) with numerical and analytical results.

Application of computational gas dynamics methods for calculating losses during rotation of solids in low vacuum conditions

On the basis of a mathematical model with distributed parameters, a method for determining aerodynamic losses during high-frequency rotation of a flywheel accumulator is developed. The power of losses due to friction of the rotor against the air is determined as a function of the pressure in the chamber. A comparative analysis of the aerodynamic losses under low vacuum conditions at various pressures of the working medium and the data obtained on the basis of empirical dependences and presented in the scientific literature on this topic is carried out. The maximum difference between the loss power values is no more than 25%. The data deviation decreases as the pressure in the chamber decreases.

All-Suture and Solid Medial Row Anchors Produce Similar Clinical Outcomes for Double Row Suture Bridge Rotator Cuff Repair (227)

Objectives:All-suture anchor use for rotator cuff repair is increasing. Potential benefits of these anchors include less bone loss from anchor hole drilling and decreased injury to the chondral surface with anchor pullout. Minimal evidence exists comparing clinical outcomes of all suture to solid medial row anchor fixation in double row suture bridge rotator cuff repair. The purpose of this study was to compare patient-reported outcomes for rotator cuff tears treated with all-suture medial row anchors to those treated with more traditional solid anchors. The null hypothesis was that there is no difference in outcomes between the all-suture and solid anchor rotator cuff repairs.Methods:Three sports medicine fellowship trained surgeons performed rotator cuff repairs using the double row suture bridge technique with minimum 3 years of follow up. Patients were separated into two groups based on whether or not they received all-suture or solid anchor fixation for the medial row of their repair. All lateral row fixation was performed with solid anchors. Primary outcomes were evaluated with telephone follow-up and included the American Shoulder and Elbow Surgery Score (ASES), Single Assessment Numeric Evaluation (SANE), and Visual Analog Scale (VAS). The Rehabilitation protocol was the same for all subjects in the study.Results:3 sports medicine fellowship trained orthopaedic surgeons performed 153 rotator cuff repairs. 91 of these subjects had all-suture fixation of the medial row and 62 received solid anchor fixation. Follow up was 3.6 years ± 0.6 for the all-suture group and 3.7 years ± 0.6 in the solid anchor group (p= 0.28). ASES scores were 92 ± 16 in the all-suture group and 90 ± 17 in the solid group (p =0.35). SANE scores were 91 ± 13 in the all-suture and also 91 ± 13 in the solid anchor cohort (p = 0.97). VAS scores were 1.1 ± 2.0 in the all-suture and 0.7± 1.8 in the solid anchor group (p=0.17). There were no significant differences between groups with regards to re-operation rate or anchor configuration.Conclusions:All suture anchors used in medial row fixation for double row suture bridge rotator cuff repairs have similar clinical outcomes to rotator cuff tears treated in similar fashion with solid medial row anchors.

Stress field and tectonic regime of Central Iran from inversion of the earthquake focal mechanisms

This paper provides a latest compilation of data on the present-day stress pattern in Central Iran and its tectonic regime. We compiled 103 focal mechanism data collected from the Global Centroid Moment Tensor Project (GCMT) including data from Harvard University (HRVD) and the International Seismological Center (ISC). Stress inversion of all shallow focal depths provides a first order stress field with a N029°E maximum horizontal compressive stress (SHmax) direction corresponding to a general compressive tectonic regime. In order to reconstruct the second and third order stress fields, we subdivided the study area into eight zones on the basis of their structures, relatively similar focal mechanisms and relatively homogeneous deformation. For each zone and for the same data set, reduced stress tensors have been obtained by formal stress inversion using the Win-Tensor program and modified SLICK method. Both inversion methods show similar results for horizontal stress axes orientations and for the tectonic regimes.The obtained NE-SW direction of the first order stress field is related to Arabia-Eurasia convergence as confirmed by the geodetic measurements. This stress field is responsible for accommodation of shortening within Central Iran and right-lateral movement along the N-S faults as well as left-lateral movement along the E-W faults. Solid block rotation between strike-slip and thrust faults, vertical rotation of the fault bounded blocks, escape tectonics, block extrusion and strain partitioning occurred due to second and third order stress fields with variable SHmax directions from N006° to N081° and in different tectonic regimes.

Core-shell microstructured nanocomposites optimized based on Box–Behnken design for enhanced suppression of hydrogen co-flow flames

Combustion characteristics of hydrogen-containing syngas are distinct from those of traditional hydrocarbon fuels. However, the efficiency for any fire extinguishant on syngas/air flame suppression has not been validated up to now. In this study, we developed novel core-shell microstructured nanocomposites (CSMNs) with inner seawater for syngas/air fire extinguishing. To optimize the preparation conditions, we adopted a three-factor three-level Box-Behnken design (BBD). The corrosion rate and minimum extinguishing concentration of CSMNs were determined by corrosion tests and Cup-burner experiments, respectively. Results showed that the BBD method exhibits good agreement between experimental data and fitted models. By applying numerical optimization, we determined that solid mass fraction, rotation speed, and rotation time in a range of 2–10%, 4000–8000 rpm, and 60–180 s, respectively, are the optimal preparation conditions for the CSMN preparation. The degree of corrosion rate and mass concentration in co-flow gaseous fuel/air fire suppression were reduced by more than 50% compared to an aqueous seawater solution. The updated methods can be used to study the fire inhibition efficiency of the emerging class of composite materials with the core-shell structure. This does not only provide solutions for syngas/air flame inhibition, but it also gives new insight into the application of seawater for fire extinguishment.

Construction of a programmed trajectory in the configuration space of rotations for solving the problem of the solid rotation

The paper proposes method of programmed control based on the concept of solving the inverse dynamic problem. As a configurational space of rotations, it is proposed to consider a sphere with a radius of 2 π in the three-dimensional Euclidean space, which is the image of the unit Sp(1) quaternions. A linear relationship has been established between the angular velocity vector of a solid in its spherical motion and the velocity of a point in a sphere allowing to relate the rotation of a solid to the motion of a point inside a three-dimensional sphere. This approach allows to clearly interpret the spherical motion of a solid by the movement of a point inside this sphere, which is used by the authors to describe the rotation of a solid at arbitrary given boundary conditions for angular positions, velocities and accelerations. An example of a smooth turn from one position to another in the case when the turn is set in the sphere in the form of a polynomial of the fifth degree is given.

Constraints on mantle viscosity and Laurentide ice sheet evolution from pluvial paleolake shorelines in the western United States

The deformation pattern of the paleoshorelines of extinct Lake Bonneville were among the first features to indicate that Earth's interior responds viscoelastically to changes in surface loads (Gilbert, 1885). Here we revisit and extend this classic study of isostatic rebound with updated lake chronologies for Lake Bonneville and Lake Lahontan as well as revised elevation datasets of shoreline features. The first order domal pattern in the shoreline elevations can be explained by rebound associated with the removal of the lake load. We employ an iterative scheme to calculate the viscoelastic lake rebound, which accounts for the deformation of the solid Earth and gravity field, to calculate a lake load that is consistent with the load-deformed paleotopography. We find that the domal deformation requires a regional Earth structure that exhibits a thin elastic thickness of the lithosphere (15–25 km) and low sublithospheric Maxwell viscosity (∼1019 Pas). After correcting for rebound due to the lake load, shoreline feature elevations reveal a statistically significant northward dipping trend. We attribute this trend to continent-scale deformation caused by the ice peripheral bulge of the Laurentide ice sheet, and take advantage of the position of these lakes on the distal flank of the peripheral bulge to provide new insights on mantle viscosity and Laurentide ice sheet reconstructions. We perform ice loading calculations to quantify the deformation of the solid Earth, gravity field, and rotation axis that is caused by the growth and demise of the Laurentide ice sheet. We test three different ice reconstructions paired with a suite of viscosity profiles and confirm that the revealed trend can be explained by deformation associated with the Laurentide ice sheet when low viscosities below the asthenosphere are adopted. We obtain best fits to shoreline data using ice models that do not have the majority of ice in the eastern sectors of the Laurentide ice sheet, with the caveat that this result can be affected by lateral variations in viscosity. We show that pluvial lakes in the western United States can place valuable constraints on the Laurentide ice sheet, the shape of its peripheral bulge, and the underlying mantle viscosity.

Turbulence of generalised flows in two dimensions

This paper discusses the generalised least-action principle and the associated concept of generalised flow introduced by Brenier (J. Am. Math. Soc., vol. 2, 1989, pp. 225–255), from the perspective of turbulence modelling. In essence, Brenier’s generalised least-action principle is a probabilistic generalisation of Arnold’s geometric interpretation of ideal fluid mechanics, whereby strong solutions to the Euler equations are deduced from minimising an action over Lagrangian maps. While Arnold’s framework relies on the deterministic concept of Lagrangian flow, Brenier’s least-action principle describes solutions to the Euler equations in terms of non-deterministic generalised flows, namely probability measures over sets of Lagrangian trajectories. In concept, generalised flows seem naturally fit to describe turbulent Lagrangian trajectories in terms of stochastic processes, an approach that originates from Richardson’s seminal work on turbulent dispersion. Still, Brenier’s generalised least-action principle has so far hardly found any practical application in the realm of fluid mechanics, let alone for turbulence modelling. The purpose of the present paper is to provide a hydrodynamical perspective on Brenier’s principle, and to assess its skills at coarse graining the Lagrangian motion of fluid particles, in order to reconstruct the space–time dynamics of the underlying Eulerian velocity fields. In practice, we rely on a statistical-mechanics interpretation of the concept of generalised flows, whereby the latter become akin to statistical ensembles of suitably defined ‘permutation flows’. We then employ Monte Carlo techniques to numerically solve the generalised least-action principle, and analyse the Eulerian and Lagrangian statistical features of the associated generalised flows. For simplicity, we restrict ourselves to two dimensions of space and consider situations of increasing complexity, ranging from solid rotation and cellular flows to freely decaying two-dimensional turbulence. Our analysis highlights a major caveat of the generalised variational principle. When used over long time lags, e.g. longer than a well-defined hydrodynamic turnover time, it generates artificial generalised flows, with non-physical statistical features. We argue that this limitation is not specifically inherent to Brenier’s formulation, but rather to the variational framework being formulated as a two-end boundary-value problem. When appropriately used over sufficiently short times, the generalised least-action principle is however relevant, and generalised flows can be explicitly constructed, that represent a space–time coarse graining of the underlying dynamics. We show numerical evidence that Brenier’s principle may then even accommodate irreversible Eulerian behaviours. This suggests that, if carefully used, generalised variational formulations could provide new tools to coarse grain genuine multi-scale hydrodynamics.

Solid Film Formation at the Tetradecane/Aqueous Hexadecyltrimethylammonium Bromide Solution Interface Studied by Interfacial Tensiometry and X-ray Reflectometry.

The effect of oil on condensed film formation in the adsorbed film of hexadecyltrimethylammonium bromide (C16TAB) at the tetradecane (C14)/water (W) interface was examined by interfacial tension and X-ray reflectivity measurements. The interfacial tension vs temperature curves have break point due to the expanded?condensed phase transition of the adsorbed film. The partial molar entropy of C16TAB at the interface changes discontinuously, whereas the interfacial density changes almost continuously at the phase transition point. The electron density profile normal to the interface manifested that the condensed film is regarded as a two-dimensional (2D) solid rotator phase in which C16TAB and C14 molecules are densely packed with perpendicular orientation. Combining the interfacial tension and X-ray reflectivity data, the mixing ratio of C16TAB to C14 in the solid film was determined to be 2:3 and thus the film is enriched in oil molecules than surfactant ones. Furthermore, the partial molar entropy change of C14 associated with solid film formation was found to be largely negative and very close to that of surface freezing of liquid alkane, manifesting that C14 molecules are well ordered to form a 2D solid film by mixing with C16TAB molecules at the interface. The solid film formation of the present system is driven by effective vdW interactions between adsorbed C16TAB and intercalated C14 molecules. The morphology of the condensed domain observed during phase transition suggested that the contact energy is more predominant than the dipole repulsion at the domain boundary, which promotes coalescence of small domains into large ones during phase transition.

Rotation of a Thin Heated Plate by Its Own Thermal Radiation

The results of the theoretical investigation of a heated solid plate rotation caused by its own thermal radiation are presented. The rotational moment of the plate with uniform temperature is due to the asymmetry of a recoil of photons of thermal radiation from different areas of its wide faces. The time dependences of the rotation angle of a rectangular plate with stable temperature and at radiative cooling are calculated. The rotation angle dependences on the plate geometric and optical parameters are studied. It is shown that the rotation angle depends nontrivially on the plate thickness because of the thickness-dependent plate emittance. The numerical calculations are performed for a silicon plate. The biggest rotation effect (rotation angle of 118.5∘ for 70 s) is obtained for a mirror black plate 0.1 mm thick at a preset plate temperature of 350 K and a background temperature of 300 K. The considered model can be useful to develop thermal motors, whose rotors consist of a set of heated plates with photon recoil asymmetry.

Pressure Profile Estimation through CFD in UBD Operation Considering with Influx to Wellbore

Nowadays, UnderBalanced Drilling (UBD) technology is widely applicable in the petroleum industry due to its advantages to an overbalanced drilling operation. UBD success depends on maintaining the drilling fluid circulating pressure below the reservoir pore pressure during operations. One of the main prerequisites of a successful UBD operation is the correct estimation of the pressure profile. In this investigation, the pressure profile was obtained with consideration of the influx to the wellbore. A spreadsheet was developed to obtain the pressure profile using an analytical solution for aerated mud in UBD operation. Moreover, a numerical simulation was employed to simulate the three-phase flow in annulus through the UBD operation and the transient Eulerian model flow via the turbulence k-e model. The effects of solid particle size and rotation of the inner pipe were considered on the pressure drop. It was observed that pressure drop was significantly increased with increasing solid particle size while it remained almost constant with increasing of the inner pipe rotation. The analytical and numerical results were compared with published experimental results and showed a good agreement.

Experimental investigation on size degradation of bridging material in drilling fluids

Solid particle size distribution (PSD) of drilling fluids is one of the key factors for the formation damage and lost circulation control. However, particle size degradation occurs during the long-term process of drilling fluid circulation in the wellbore, consequently resulting in severe formation damage. In this study, size degradation experiments of calcium carbonate solids in the period of drilling fluid circulation are conducted to understand the effect of initial particle size, rotation speed, shear time, fluid viscosity, temperature, pH, salinity, and solid concentration on size degradation of bridging material (BM). The size degradation rate of D90 is taken as the characterization of particle size degradation. The results show that ① the degree of size degradation sharply increases with increasing solid initial size, rotation speed, and shear time. Under the experimental conditions, size degradation rate of sample with D90 = 44.153 μm is up to 30%~40% at a rotation speed of 1000 rpm over 30 min; ② there is a critical particle size in the range 15–20 μm for size degradation over 90 min. When the particle size drops to this critical size, no size degradation occurs obviously; ③ size degradation decreases with increasing fluid viscosity; ④ fluid temperature, pH, salinity, and solid concentration have little effect on size degradation. The evaluation criterion of size degradation is established, and an empirical model is developed to calculate the size degradation. Two mechanisms of the formation damage induced by size degradation are revealed. Based on the particle size degradation, the strategy for the optimization of PSD and solid supplement is presented. We believe that this strategy will be of great significance to designing the particle size distribution of BM for drilling fluids in the field.

On the three-dimensional flow of a stable tangential vortex intake

Tangential vortex intakes are compact hydraulic structures commonly used in water supply, drainage and sewerage systems to convey water from high to low elevations efficiently. Tangential vortex intakes can be designed to ensure stable flows for all discharges, with high energy dissipation in the absence of significant air entrainment. However, due to the complex three-dimensional (3D) flow in the tangential vortex intake, current theoretical models are not sufficiently complete to interpret the flow process reliably. This paper presents a 3D computational fluid dynamics study of a steady tangential vortex intake flow using the Volume-of-Fluid method. For the first time, the CFD model predictions are validated against detailed point velocity measurements using laser doppler anemometry (LDA) for a wide range of inflow conditions. For a flow less than the free drainage discharge, the inflow does not interfere with the swirling flow in the drop shaft. The streamwise horizontal x-velocity at the channel-dropshaft junction varies linearly with vertical distance, while the vertical velocity follows a parabolic relation. For larger discharges the pressure and inflow velocity field is notably modified by the dropshaft swirling flow interacting with the inflow issued from the junction. While the swirling flow in the dropshaft is highly asymmetrical, it is found that the local tangential velocity can be well-approximated by a Rankine vortex – with solid rotation (forced vortex) behavior near the air core and a free vortex behavior in the main flow. In the free vortex region the vertical velocity is approximately constant in the radial direction. The predicted head-discharge relations, velocity field, pressure, and air core sizes are in excellent agreement with data. In particular the variation of air core size with flow rate is successfully predicted for the first time. The present study offers comprehensive insights of tangential vortex intake flow, and provides a basis for the hydraulic design of such vortex intake structures.

A non‐oscillatory multimoment finite‐volume global transport model on a cubed‐sphere grid using the WENO slope limiter

By using CSL3 multimoment interpolation, a piecewise cubic polynomial for spatial reconstruction can be obtained with four multimoment constraint conditions consisting of two point values at cell boundaries, one volume‐integrated average and one slope parameter at the cell center. The resulting multimoment finite‐volume scheme is of fourth‐order accuracy. A non‐oscillatory scheme can be derived by designing the proper formula to calculate the slope parameter at the cell center. A new strategy was recently proposed, using the Weighted Essentially Non‐Oscillatory (WENO) concept to determine the slope parameter. Using a WENO‐type limiter, the multimoment reconstruction can effectively remove nonphysical oscillations while keeping fourth‐order accuracy in smooth regions. In this study, a WENO‐type slope limiter is proposed and implemented in our multimoment finite‐volume global transport model based on the cubed‐sphere grid. The widely used benchmark tests, including both solid rotation and complicated deformational advection cases, are checked to verify the performance of the proposed global transport model. Numerical results reveal that a WENO‐type slope limiter can greatly improve the accuracy of the multimoment finite‐volume model compared with the former Total Variation Diminishing (TVD)‐type limiter. Furthermore, the proposed limiter is constructed over a compact stencil of only three adjacent cells. Without any user‐defined or problem‐dependent parameters, the present model is very promising for practical applications.

Multiple responses optimization of instant dark tea production by submerged fermentation using response surface methodology.

In this study, submerged fermentation mode for preparing instant dark tea production was developed through utilizing industrial low grade green tea as raw material and Aspergillus niger as fermentation microbe starter. The fermentation parameters (inoculum size, liquid-solid ratio and rotation speed) were optimized by using Box-Behnken design and response surface methodology (RSM) with desirability function, the theabrownins content, redness and turbidity value as responses. The optimal conditions were set as follow: inoculum size of 5.3% (v/v), liquid-solid ratio of 27.78mL/g, and rotation speed of 182r/min. The optimized conditions model showed a good correlation between the predicted and experimental values. Further, the optimum product of instant dark was achieved in a 3-L laboratory fermenter, and the main parameters of product were theabrownins content of 140.92g/kg and redness value of 40.78 and turbidity of 90.98 NTU. Sensory evaluation showed that the instant dark tea infusion approached mellow mouthfeel, an aroma of mint and a good overall acceptance.