Deriving the PEE proposal from the locking bit thread configuration

In the holographic framework, we argue that the partial entanglement entropy (PEE) can be explicitly interpreted as the component flow flux in a locking bit thread configuration. By applying the locking theorem of bit threads, and constructing a concrete locking scheme, we obtain a set of uniquely determined component flow fluxes from this viewpoint, and successfully derive the PEE proposal and its generalized version in the multipartite cases. Moreover, from this perspective of bit threads, we also present a coherent explanation for the coincidence between the BPE (balanced partial entanglement)/EWCS (entanglement wedge cross section) duality proposed recently and the EoP (entanglement of purification)/EWCS duality. We also discuss the issues implied by this coincident between the idea of the PEE and the picture of locking thread configuration.

Compressor Maps and Coupling: Symmetry, Paradox, and Clarity

The most common compressor map framework, referred to here as the β-framework, will be shown to suffer from limitations that grow more troublesome in the multiple-map environment. When maps are coupled in series in the β-framework, it is very common to find operating points that are physically unrealizable, but these cannot generally be avoided without first generating them. A feasible situation is described in which the β-framework leads to an apparent physical paradox. In the proposed S-framework, the map itself is recast in terms of independent variables (corrected speed and exit corrected flow) and dependent variables (inlet corrected flow and temperature ratio). The propagation of information in map coupling is split into an upstream-marching corrected flow ‘flux’ and a downstream-marching temperature ‘flux’. Finding the equilibrium operating point requires only finding a simple intersection between curves. The S-framework is then developed further into a more compact S’-framework that exhibits a natural set of qualitative symmetries. The S- and S’-frameworks are shown to simplify compressor map expression, resolve the problems shown with the β-framework, and aid intuition with regard to off-design phenomena. The resolution of the paradox using the S’-framework is a new description of multistage compressor performance hysteresis.

Numerical Simulation on Mesoscale Mechanism of Seepage in Coal Fractures by Fluid-Sloid Coupling Method

Trying to reveal the mechanism of gas seepage in coal is of significance to both safe mining and methane exploitation. A series of FEM numerical models were built up and studied so as to explore the mesoscale mechanism of seepage in coal fractures. The proposed mesoscale FEM model is a cube with micron fractures along three orthogonal directions. The distribution of velocity and pressure under fluid-solid coupling was obtained, and furthermore, the seepage flow flux and an equivalent permeability of the whole model were calculated. The influences of fracture width, outlet velocity, and in situ stress level on seepage were investigated. The numerical results show that nonlinear Darcy seepage occurs during low velocity zone. The permeability is increased linearly with the increasing of facture width and outlet velocity. A certain change of lateral coefficient of in situ stress also affects seepage. The permeability is increased sharply once deviating the isotropic spherical stress state, but it is no longer changed obviously after the lateral coefficient has been increased or decreased more than 20%. The mesoscale seepage mechanism in coal fractures has been preliminarily revealed by considering fluid-solid coupling effect, and the key factors influencing fluid seepage in coal fractures were demonstrated. The proposed methods and results will be helpful to the further study of seepage behaviour in coal with more complex structures.

Electrochemical Characterization of Cellulose Acetate/Chitosan Membrane in Presence and Absence of Nonionic Surfactant in Monovalent Electrolytic Solution

The influence of surfactant on cellulose acetate/chitosan membrane has been investigated. A basic approach to cellulose acetate/chitosan membrane is also mentioned. Nonionic surfactants are disrupted the normal permeability of the characteristic membrane. Electrochemical characterization such as conductance, flow, flux and permeability are measured in various concentrations of the electrolyte and surfactants. Membrane potential is determined by the combination of the properties of ions of the electrolyte, surfactant and membrane. The synthesized membrane was found to be cation selective with measured membrane potential found to be negative in all cases. The value of membrane potential was varying in different concentration of the electrolyte and surfactant. The Teorell Meyer and Sievers (TMS) theoretical method was employed for calculating the Transport number, perm selectivity and fixed charge density of the membrane by using the data of membrane potential across normal and surfactant modified membrane with electrolytic solution of NaCl. The variation of fixed density and perm selectivity also depends on the concentration of the electrolyte and surfactant (Tween 20 and Tween 60).

Analysis of Event-based Hydrological Processes at the Hydrohill Catchment Using Hydrochemical and Isotopic Methods

Hydrochemical and isotopic techniques have been widely applied in hydrological sciences because isotopic tracers can identify water sources and hydrochemical tracers can discern runoff flow paths. To better understand the hydrological process, we combined hydrochemical and isotopic techniques under controlled experimental conditions to investigate hydrological process from rainfall to runoff in the Hydrohill experiment catchment, a typical artificial catchment in Chuzhou, China. Hydrochemical and isotopic data, i.e., pH, electric conductivity (EC), total dissolved solids (TDS), anions (Cl−, NO3-, SO42- and HCO3-), cations (K+, Na+, Ca2+ and Mg2+) and dissolved Si, 18O and D in water samples were collected during a rainfall event in 2016, and used to determine the hydrochemical and isotopic characteristics of rainfall and runoff components. We applied EC, TDS, SO42-, Ca2+, Mg2+, 18O and D as tracers to investigate rainfall-runoff processes in the experimental catchment. Runoff flow paths could be well identified by the relationship between 18O and EC, TDS, SO42-, Ca2+ and Mg2+. The quantity of flow flux and mass fluxes of main hydrochemical and isotopic tracers gauged at the catchment outlet shows applicable tracers (Ca2+, Mg2+, SO42-, and 18O) are mainly from deep groundwater runoff (from soil layer of 60–100 cm beneath ground surface). Contributions of the event water and pre-event water to the total runoff during the rainfall-runoff process are different. The quantitative results were very encouraging as a basis to develop hydrological models for further study.

Numerical and Experimental Study of Turbulent Mixing Characteristics in a T-Junction System

The mixing, migration, and degradation of pollutants in sewers are the main causes for pipeline corrosion and the increased pollution scope. The clarification of the turbulent mixing characteristics in pipelines is critical for finding the source of pollution in a timely fashion and inspecting pipelines’ damaged locations. In this paper, numerical simulations and experiments were conducted to investigate the turbulent mixing characteristics in pipelines by studying a T-junction system, of which four variables (main pipe diameter φ, cross-flow flux Q, mixing ratio δ, the incident angle of T-junctions θ) were considered. The coefficient of variation (COV) of the salt solution was selected as the evaluation index and effective mixing length (LEML) was defined for quantitative analysis. The numerical results were found to be in good agreement with the experimental results. The results reveal that the values of LEML rise as Q or φ increase and decrease with the increase of δ, where the influence of φ is much greater than Q and δ, and there is no obvious regularity between LEML and θ. By dimensional analysis and multivariate nonlinear regression analysis, a dimensionless relationship equation in harmony with the dimensional analysis was fitted, and a simplified equation with the average error of 4.01% was obtained on the basis of correlation analysis.

Influence of combination forms of intact sub-layer and tectonically deformed sub-layer of coal on the gas drainage performance of boreholes: a numerical study

High concentration and large flow flux of gas drainage from underground coal seams is the precondition of reducing emission and large-scale use of gas. However, the layered occurrence of coal seams with tectonically deformed sub-layers and intact sub-layers makes it difficult to effectively drain gas through commonly designed boreholes. In this study, the gas drainage performance in coal seams with different combinations of tectonically deformed sub-layers and intact sub-layers was numerically analyzed. The analysis results show that the gas drainage curve changes from a single-stage line to a dual-stage curve as the permeability ratios of Zone II (kII) and Zone I (kI) increase, raising the difficulty in gas drainage. Furthermore, a dual-system pressure decay model based on the first-order kinetic model was developed to describe the dual-stage characteristics of pressure decay curves with different permeability ratios. In the end, the simulation results were verified with reference to in-situ drainage data from literature. The research results are helpful for mines, especially those with layered coal seams comprising tectonically deformed sub-layers and intact sub-layers, to choose appropriate gas drainage methods and develop the original drainage designs for achieving better gas drainage performance.

Hydrogeological characterization of the aquifers of the Salitre region through stable isotopes (δD and δ18O) and geochemistry

The important aquifers of the Salitre basin are encompassed within the geological framework of the metasedimentary rocks of the Chapada Diamantina Group and in the carbonate rocks of the Una Group and Caatinga Formation. For fifty five water samples from carbonate aquifers, dD values varied from −43‰ to −10‰, and d18O values from −5.9‰ to −3.3‰, with high concentrations of dissolved total salts. The variability allowed us to discern three process of salinization: i) samples with more negative isotope values are produced primarily by transpiration and/or dissolution in the evaporitic rocks ii) samples with less negative isotopic values indicate that evaporation is predominant; and iii) samples from metasedimentary aquifers, with low concentrations of dissolved total salts and dD values ranging from −36‰ to −20‰ and 18O values from −5,4‰ to −3,5‰ indicated low evaporation. The piezometric map indicated that the groundwater flow flux is from both the east and west towards the center of the basin and that the general direction of surface water flux is from south to north, where the water level is closer to the surface.Keywords: Carbonate rocks, semiarid region, hydrochemistry, stable isotopes, karst aquifer. ResumoOs aquíferos importantes da bacia do Salitre estão abrangidos dentro do arcabouço geológico metassedimentares do Grupo Chapada Diamantina e nas rochas carbonáticas do Grupo Una e da Formação Caatinga. Para cinquenta e cindo amostras de água dos aquíferos carbonatados, os valores de dD variaram de -43 ‰ a −10 ‰ e os valores de d18O de -5,9 ‰ a -3,3 ‰, com altas concentrações de sais totais dissolvidos. A variabilidade indica três processos de salinização: i) amostras com mais valores de isótopos negativos são produzidas primariamente por transpiração e/ou dissolução nas rochas evaporíticas; ii) amostras com menos valores isotópicos negativos indicam que a evaporação é predominante; e iii) amostras de aquíferos metassedimentares, com baixas concentrações de sais totais dissolvidos e valores de D variando de −36 ‰ a −20 ‰ e valores de d18O de -5,4 ‰ a −3,5 ‰ indicaram pouca evaporação. O mapa isopiezométrico indicou que o fluxo subterrâneo é tanto do leste quanto do oeste em direção ao centro da bacia e que a direção geral do fluxo de superfície é do sul para o norte, onde o nível freático está mais próximo da superfície.Palavras-chave: Rochas carbonáticas, região semiárida, hidroquímica, isótopos estáveis, aquíferos cársticos.

Effect of Mixed-Flow Fans with a Newly Shaped Diffuser on Heat Stress of Dairy Cows Based on CFD

Mixed-flow fans (MFF) are widely used to reduce the heat stress in dairy cows in summer. Our research team developed MFFs with a newly shaped diffuser with the length of 250 mm and the circumferential angle of 150°, which have better performance in terms of maximum flow flux and energy efficiency. However, how the elevation angle of the diffuser influences the performance of MFFs and how the optimal fan perform in the field experiment has not been studied yet. In this paper, the diffuser was optimized by CFD (Computational Fluid Dynamics) simulation of the fan and a laboratory prototype test. An orthogonal test showed no interaction among length, circumferential angle, and elevation angle. The diffuser with an elevation angle of 10° performed better than that with an elevation angle of 0°, showing increased jet lengths, flow flux, and energy efficiency by 0.5 m, 0.69%, and 1.39%, respectively, and attaining greater axial wind speeds and better non-uniformity coefficients at the dairy cattle height. Then, through on-site controlled trials, we found that the 10°/150°/250 mm diffusers increased the overall average wind speeds by 9.4% with respect to the MFFs without a diffuser. MFFs with the newly shaped diffuser were used for field tests, and their effectiveness in alleviating heat stress in dairy cows was evaluated by testing environmental parameters and dairy cows’ physiological indicators. Although the temperature–humidity indexes (THIs) in the experimental barn with the optimized fan at different times were lower than those in the controlled barn, the environmental conditions corresponded to moderate heat stress. However, this was not consistent with cow's respiratory rate and rectal temperature. Finally, on the basis of the CFD simulation of a dairy cow barn, the equivalent temperature of cattle (ETIC), which takes into account the effect of air velocity, showed that the environment caused moderate heat stress only at 13:00, but not at other times of the day. This shows that ETIC is more accurate to evaluate heat stress.