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Focused energy delivery (FED) is a technique that can precisely bring energy to the specific region, which arouses wide attention in precision electronic warfare (PREW). This paper first proposes a joint optimization model with respect to the locations of the array and the transmitted signals to improve the performance of FED. As the problem is nonconvex and NP-hard, particle swarm optimization (PSO) is adopted to solve the locations of the array, while designing the transmitted signals under a feasible array is considered as a unimodular quadratic program (UQP) subproblem to calculate the fitness criterion of PSO. In the PSO-UQP framework established, two methods are presented for the UQP subproblem, which are more efficient and more accurate respectively than previous works. Furthermore, a threshold value is set in the framework to determine which method to adopt to take full advantages of the methods above. Meanwhile, we obtain the maximum localization error that FED can tolerate, which is significant for implementing FED in practice. Simulation results are provided to demonstrate the effectiveness of the joint optimization algorithm, and the correctness of the maximum localization error derived.

Context The influences of diabetes duration and glycemic control and their potential interplays on the risk of heart failure (HF) remain unclear. Objective This work aimed to investigate the association of diabetes duration and glycemic control with the risk of HF. Methods A total of 23 754 individuals with diabetes but without HF during the baseline recruitment of UK Biobank were included in this study. Duration of diabetes was self-reported, and the status of glycemic control was reflected by glycated hemoglobin A1c (HbA1c) levels. Their associations with incident HF were assessed using multivariate Cox models adjusting for traditional risk factors. Results Duration of diabetes and HbA1c levels both were positively associated with the risk of HF. The hazard ratios (HRs) (95% CI) for diabetes durations of 5 to less than 10, 10 to less than 15, and 15 years or more were 1.09 (0.97-1.23), 1.13 (0.97-1.30), and 1.32 (1.15-1.53), respectively (vs < 5 years); and the HRs for HbA1c of 53.0 to less than 58.5 mmol/mol (7.0% to < 7.5%), 58.5 to less than 63.9 mmol/mol (7.5% to < 8.0%), and 63.9 mmol/mol or greater (8.0%) were 1.15 (1.02-1.31), 1.07 (0.91-1.26), and 1.46 (1.30-1.65), respectively (vs < 53.0 mmol/mol [7.0%]). Individuals with the longest disease duration (≥ 15 years) and poorer glycemic control (HbA1c ≥ 63.9 mmol/mol [8.0%]) had a particularly higher risk of HF (P for interaction = .026). Conclusion The risk of HF among individuals with diabetes increases with a longer duration of diabetes and increasing HbA1c levels. This finding may contribute to the individualized prevention of HF in patients with diabetes if being considered in clinical practices and policy-making.

In this paper, we consider the problem of space–time adaptive processing (STAP) when inaccurate target (namely the angle and Doppler frequency of target are uncertain) exists in the training samples, which would result in target self-nulling effects and degrade the performance of STAP significantly. A robust STAP method is proposed by reconstructing the clutter-plus-noise covariance matrix (CPNCM) and estimating the target spatial–temporal steering vector. The CPNCM is reconstructed by integrating clutter Capon spectrum over a region which includes the clutter component and is separated from the region of interest (ROI), and we use a discrete sum method to compute the integral approximately for approximate computation. Similarly, the ROI covariance matrix is calculated by integrating signal Capon spectrum over the ROI which includes the signal component. After that, the correlation coefficient between the presumed steering vector and the dominant eigenvectors of ROI covariance matrix is computed. The spatial–temporal steering vector of target is then estimated by searching for the eigenvector corresponding to the maximum correlation coefficient. Finally, a novel robust STAP weight is obtained based on the reconstructed CPNCM and estimated spatial–temporal steering vector of target. Compared to conventional robust STAP methods, simulation examples demonstrate that the proposed method can obtain a more robust performance against target spatial–temporal steering vector mismatch, better output signal-to-clutter-plus-noise (SCNR) and target detection performance in practical clutter environment.

Different discrete velocity quadrature rules are analyzed and applied in gas-kinetic unified algorithm (GKUA) for rarefied free-molecule transition to continuum flows, including the original and modified Gauss–Hermite quadrature rules, the composite Newton–Cotes integration methods, the multi-subinterval Gauss–Legendre numerical quadrature rule and the Gauss–Chebyshev integral rule. Mathematical description and basic procedures of GKUA are presented briefly in solving the gas flow problems covering various flow regimes on the basis of the direction solution to the unified kinetic model of the Boltzmann equation. The numerical analyses and the application conditions of these quadrature rules are given in detail, as well as the evaluating method for the discretized velocity ordinate (DVO) points and their corresponding weights of each rule. According to the comparisons for some Gauss-type function integrations, the original and modified Gauss–Hermite quadrature rules can obtain the integration results with enough accuracy by using least DVO points among these rules, while the impossibility of more nodes limits the application scope of these two quadrature rules. Other four rules can conduct the problems with a needful wide integral interval, even if they use more DVO points than the Gauss–Hermite rules. Besides, the multi-subinterval Gauss–Legendre and the Gauss–Chebyshev rules can use less DVO points to obtain accurate integration results than the other two rules, which demonstrate their advantage and are recommended to be applied in GKUA to solve the Boltzmann model equation efficiently. Numerical simulations for the Sod and Lax shock-tube problems and the shock-density wave disturbing interaction problems are conducted by using GKUA with the above quadrature rules to make comparison. All quadrature rules can obtain nice accurate results with different number of the DVO points. The original and modified Gauss–Hermite quadrature rules, using the least DVO nodes to obtain results with enough computed precision, are the best options for GKUA to simulate low mach number flow regimes, while the Gauss–Chebyshev quadrature rule, which can obtain results with adequate and controllable precision for a wide integral interval using little DVO nodes, is the most appropriate quadrature rule for GKUA solving some complex and high mach number flows covering various flow regimes.

The corresponding physical model was established by using a tunnel, and the appropriate fire source power was selected. The minimum export momentum was calculated by the minimum export momentum method, and the minimum outlet jet velocity of the air curtain is given as umin = 14m/s. The change of the concentration of CO, visibility and temperature in the same fire environment under the influence of piston wind was analyzed by CFD simulation software under different jet velocity of air curtain, comparison of the concentration of CO, visibility and temperature at different jet speed of air curtain changes with time simultaneously, to study the effect of jet velocity of air curtain on the spread characteristics of flue gas of tunnel fire. The results show that when the jet velocity of air curtain is 14m/s, it can control the smoke best.

In this paper, the unified gas-kinetic wave-particle (UGKWP) method is further developed for diatomic gas with the energy exchange between translational and rotational modes for flow study in all regimes. The multiscale transport mechanism in UGKWP is coming from the direct modeling in a discretized space, where the cell's Knudsen number, defined by the ratio of particle mean free path over the numerical cell size, determines the flow physics simulated by the wave particle formulation. The non-equilibrium distribution function in UGKWP is tracked by the discrete particle and analytical wave. The weights of distributed particle and wave in different regimes are controlled by the accumulating evolution solution of particle transport and collision within a time step, where distinguishable macroscopic flow variables of particle and wave are updated inside each control volume. With the variation of local cell's Knudsen number, the UGKWP becomes a particle method in the highly rarefied flow regime and converges to the gas-kinetic scheme (GKS) for the Navier-Stokes solution in the continuum flow regime without particles. Even targeting on the same solution as the discrete velocity method (DVM)-based unified gas-kinetic scheme (UGKS), the computational cost and memory requirement in UGKWP could be reduced by several orders of magnitude for the high speed and high temperature flow simulation, where the translational and rotational non-equilibrium becomes important in the transition and rarefied regime. As a result, 3D hypersonic computations around a flying vehicle in all regimes can be conducted using a personal computer. The UGKWP method for diatomic gas will be validated in various cases from one dimensional shock structure to three dimensional flow over a sphere, and the numerical solutions will be compared with the reference DSMC results and experimental measurements., Comment: 35 pages, 15 figures, 1 table

Shale gas flow at the pore scale is very challenging to simulate due to high Knudsen numbers ( K n ), low speeds and complicated pore geometries. The direct simulation BGK (DSBGK) method and the discrete velocity method (DVM) are promising methods to simulate three-dimensional (3D) gas flows in the shale rock. As the grid-convergence accuracy and computational cost highly depend on the spatial and molecular velocity grids, here we present a rigorous study of the computational performance of the two methods by simulating gas flows through the standard 3D Sierpinski carpet. In this study, we found reasonable agreement between the DSBGK and DVM simulations when comparing the velocity profiles and permeability curves obtained by using fine spatial and velocity grids. However, the grid convergence of the DSBGK simulation is faster than that of the DVM, which requires a very large number of spatial and velocity grids for convergence. Consequently, the DSBGK simulation is orders of magnitude cheaper than the DVM simulation in terms of the CPU time and memory usage. While the DVM requires a high-performance computing facility to meet the memory demand of several hundreds of gigabyte for simulating this 3D flow problem, the DSBGK simulation can run on an ordinary laptop. This work therefore demonstrates the DSBGK method as a practical simulation tool for 3D pore-scale gas flows in the shale rock. Converged results generated in this study can be used as comparison data by other simulation methods.

The unsteady process of rarefied jet flows expanding into a vacuum is numerically solved by the Gas-Kinetic Unified Algorithm (GKUA) based on the Boltzmann model equations. The discrete velocity ordinate method (DVOM) is adopted to discretize the velocity space of the molecular velocity distribution function, while the corresponding numerical integral technique is developed to evaluate macroscopic flow variables, including number density, flow velocity, temperature and so on. The time-explicit finite difference scheme is constructed to capture the unsteady evolution of the discrete velocity distribution functions at each DVO point by using the unsteady time-splitting method. The multi-block docking grid technique is designed for different regions of flow field in physical space with self-adaptive adjustment. Then, the supersonic planar jet flows with the wide range of Knudsen numbers, from 100 to 0.1, are solved numerically and discussed, including startup to steady state and shutting down. The GKUA results of free-molecule jet flows are analyzed and compared with the Maxwellian analytical solutions for collisionless plume flows, in which good agreement shows the validity and accuracy of the present numerical method. When taking the collision effect into account, the unsteady jet flows with different Knudsen numbers are computed by the present GKUA method. It is shown that the collision term of the Boltzmann model equation plays an important role in this rarefied gas diffusion into the back flow when Kn ≤ 10. However, the colliding relaxation term have a little influence on the kernel region in the startup process for Kn ≥ 0.1. In general, the convective transport term of the Boltzmann model equation dominates the kernel region of the jet flow during the unsteady process of gas expanding into a vacuum. The numerical experience indicates that the present GKUA can provide a vital tool for solving unsteady flow problems covering various flow regimes by directly tracing the time evolution of the Boltzmann-type velocity distribution function.

A Cartesian grid method combined with a simplified gas kinetic scheme is presented for subsonic and supersonic viscous flow simulation on complex geometries. Under the Cartesian mesh, the boundaries are represented by a set of direction-oriented boundary points, and the computational grid points are classified into four different categories, the fluid point, the solid point, the drop point, and the interpolation point. A constrained weighted least square method is employed to evaluate the physical quantities at the interpolation points. Different boundary conditions, including isothermal boundary, adiabatic boundary, and Euler slip boundary, are presented by different interpolation strategies. We adopt a simplified gas kinetic scheme as the flux solver for both subsonic and supersonic flow computations. The methodology of constructing a simplified kinetic flux function can be extended to other flow systems. A few numerical examples are used to validate the Cartesian grid method and the simplified flux solver. The reconstruction scheme for recovering the boundary conditions of compressible viscous and heat conducting flow with a Cartesian mesh can provide a smooth distribution of physical quantities at solid boundary, and present an accurate solution for the flow study with complex geometry.

The general synthetic iteration scheme (GSIS) is extended to find the steady-state solution of nonlinear gas kinetic equation, removing the long-standing problems of slow convergence and requirement of ultra-fine grids in near-continuum flows. The key ingredients of GSIS are that the gas kinetic equation and macroscopic synthetic equations are tightly coupled, and the constitutive relations in macroscopic synthetic equations explicitly contain Newton's law of shear stress and Fourier's law of heat conduction. The higher-order constitutive relations describing rarefaction effects are calculated from the velocity distribution function, however, their constructions are simpler than our previous work (Su et al. Journal of Computational Physics 407 (2020) 109245) for linearized gas kinetic equations. On the other hand, solutions of macroscopic synthetic equations are used to inform the evolution of gas kinetic equation at the next iteration step. A rigorous linear Fourier stability analysis in periodic system shows that the error decay rate of GSIS can be smaller than 0.5, which means that the deviation to steady-state solution can be reduced by 3 orders of magnitude in 10 iterations. Other important advantages of the GSIS are (i) it does not rely on the specific form of Boltzmann collision operator and (ii) it can be solved by sophisticated techniques in computational fluid dynamics, making it amenable to large scale engineering applications. In this paper, the efficiency and accuracy of GSIS is demonstrated by a number of canonical test cases in rarefied gas dynamics., 25 pages, 17 figures; Version 3, major revision of text and reformed/re-organized equations, added numerical analysis but numerical results are not changed

Low speed thermal transpiration gas flows through micro-channels are simulated by the direct simulation BGK (DSBGK) method that is based on the Bhatnagar-Gross-Krook model equation. Different from the ordinary application of BGK equation having the viscosity matched, we selected its relaxation time according to the thermal conductivity coefficient and thus significantly improved the accuracy. In comparing the detailed flow field solutions of a 2D Knudsen pump, the validation by the standard direct simulation Monte Carlo (DSMC) method shows that the improved BGK equation has about the same accuracy as the Shakhov equation that is solved by the well-developed gas kinetic unified algorithm (GKUA). We also present the ordinary application of BGK equation with noticeable error to clearly show the difference made in our study. Then, the efficient DSBGK method is applied to simulate the low-speed rarefied gas flows in 3D real-size thermal transpiration problem to show its applicability and its validity is verified by comparing with the experimental measurement of mass flow rates. The DSBGK simulation results have excellent agreement with experimental data for three types of gases over a wide range of Knudsen number. Additionally, the channel end effect is also studied and discussed as a prerequisite for high-fidelity modeling, otherwise it will be mistakenly interpreted as the variation of accommodation coefficients of the molecular reflection process on the solid boundary.

Evaluation of plant response to nutrients may be difficult in soil grown plants due to complex nutrient chemical, physical and biological interactions. Hydroponics is an alternative method of plant nutrient supply which avoids soil-nutrient reaction complexities. Eucalyptus and related species are highly valued as fast-growing woody plants. We conducted a study to evaluate the feasibility of producing eucalypt seedlings hydroponically, and investigate if the seedling growth and morphology could be manipulated through regulated hydroponic nutrient supply. We focused on phosphorus nutrition since it is one of the commonly growth limiting plant nutrient element. Two important eucalypts species Eucalyptus dunnii and Corymbia citriodora were grown hydroponically in a greenhouse at six P concentrations (0, 0.01, 0.1, 0.5, 1 and 2 mM) for two months with 1/4 strength modified (different P concentrations) Hoagland solution in a glass greenhouse. Phosphorus nutrition significantly affected seedlings’ leaf area, height, stem diameter and biomass ( p i ) toxicity, micronutrient unavailability and uptake antagonism due to excessive P. There was a close relationship between the Hoagland solution P concentration, plant tissue P and nitrogen (N) concentration. Phosphorus use efficiency (PUE) was highest at lower (0.01 mM) P concentrations (13 g mM −1 for C . citriodora and 19 g mM −1 for E. dunniii ). Low P concentration (0.1 mM) was sufficient to produce good quality seedlings in both species. Our study confirmed that hydroponic system could be used successfully to produce high vigor woody plants seedlings. The eucalyptus seedlings had sufficient roots and shoot growth. The general root lengths for both species were more than 30 cm long.

This article reviews rarefied gas flow computations based on nonlinear model Boltzmann equations using deterministic high-order gas-kinetic unified algorithms (GKUA) in phase space. The nonlinear Boltzmann model equations considered include the BGK model, the Shakhov model, the Ellipsoidal Statistical model and the Morse model. Several high-order gas-kinetic unified algorithms, which combine the discrete velocity ordinate method in velocity space and the compact high-order finite-difference schemes in physical space, are developed. The parallel strategies implemented with the accompanying algorithms are of equal importance. Accurate computations of rarefied gas flow problems using various kinetic models over wide ranges of Mach numbers 1.2–20 and Knudsen numbers 0.0001–5 are reported. The effects of different high resolution schemes on the flow resolution under the same discrete velocity ordinate method are studied. A conservative discrete velocity ordinate method to ensure the kinetic compatibility condition is also implemented. The present algorithms are tested for the one-dimensional unsteady shock-tube problems with various Knudsen numbers, the steady normal shock wave structures for different Mach numbers, the two-dimensional flows past a circular cylinder and a NACA 0012 airfoil to verify the present methodology and to simulate gas transport phenomena covering various flow regimes. Illustrations of large scale parallel computations of three-dimensional hypersonic rarefied flows over the reusable sphere–cone satellite and the re-entry spacecraft using almost the largest computer systems available in China are also reported. The present computed results are compared with the theoretical prediction from gas dynamics, related DSMC results, slip N–S solutions and experimental data, and good agreement can be found. The numerical experience indicates that although the direct model Boltzmann equation solver in phase space can be computationally expensive, nevertheless, the present GKUAs for kinetic model Boltzmann equations in conjunction with current available high-performance parallel computer power can provide a vital engineering tool for analyzing rarefied gas flows covering the whole range of flow regimes in aerospace engineering applications.

Phase fraction and solidification path of high Zn-containing Al-Zn-Mg-Cu series aluminum alloy were calculated by calculation of phase diagram (CALPHAD) method. Microstructure and phases of Al-9.2Zn-1.7Mg-2.3Cu alloy were studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The calculation results show that η(MgZn2) phase is influenced by Zn and Mg. Mass fractions of η(MgZn2) in Al-xZn-1.7Mg-2.3Cu are 10.0%, 9.8% and 9.2% for x=9.6, 9.4, 8.8 (mass fraction, %), respectively. The intervals of Mg composition were achieved for θ(Al2Cu)+η(MgZn2), S(Al2CuMg)+η(MgZn2) and θ(Al2Cu)+S(Al2CuMg)+η(MgZn2) phase regions. Al3Zr, α(Al), Al13Fe4, η(MgZn2), α-AlFeSi, Al7Cu2Fe, θ(Al2Cu), Al5Cu2Mg8Si6 precipitate in sequence by no-equilibrium calculation. The SEM and XRD analyses reveal that α(Al), η(MgZn2), Mg(Al,Cu,Zn)2, θ(Al2Cu) and Al7Cu2Fe phases are discovered in Al-9.2Zn-1.7Mg-2.3Cu alloy. The thermodynamic calculation can be used to predict the major phases present in experiment.

The microstructural evolution of Al–0.66Mg–0.85Si alloy was investigated by optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The as-cast microstructure is typical dendritical structure, consisting of α(Al), Al(FeMn)Si, Mg 2 Si, AlCuMgSi and Si phases. The electron diffraction analyses indicate that the Al(FeMn)Si phase is Al 15 (FeMn) 3 Si 2 and the AlCuMgSi phase is Q (Al 1.9 CuMg 4.1 Si 3.3 ). There are two kinds of Mg 2 Si phases in the as-cast microstructure. One is formed in the casting process, and the other is formed in the cooling process after casting process is finished. The phases have different crystal structures. After homogenization treatment at 545 °C for 20 h, Mg 2 Si, Si and Q intermetallic compounds are dissolved into matrix completely, and the remaining phases are α(Al) and Al 15 (FeMn) 3 Si 2 . The size of Al 15 (FeMn) 3 Si 2 phase is decreased, and the phase is spheroidized and distributes along grain boundary discontinuously. The Zn-containing phases are not found during solidification and homogenization process.

The developments of several kinetic numerical methods for solving the semiclassical Boltzmann-BGK equation are presented. The methods considered include the direct solver in phase space and lattice Boltzmann method. For the direct phase space solver, the discrete ordinate methods in velocity space and explicit and implicit high resolution schemes in physical space are combined to yield the desired scheme. A brief overview of the core computational methods which has been originated and evolved over the past 30 years starting at NASA-Ames/Stanford is reviewed. For the semiclassical lattice Boltzmann method, a multiple relaxation time approach is developed. The method is directly derived by projecting the kinetic governing equation onto the tensor Hermite polynomials and various hydrodynamic approximation orders can be achieved. The semiclassical incompressible Navier–Stokes equations can be recovered via a Chapman–Enskog multi-scale expansion. Applications of these kinetic numerical methods to semiclassical hydrodynamic transport involving various kinds of carrier particles are then illustrated by specific examples. The general hydrodynamic transports in gases of arbitrary statistics and in wide flow regimes are emphasized. The results indicate distinct characteristics of the effects of quantum statistics.

The soil organic matter and nutrients are fundamental for the sustainability of pear production, but little is known about the spatial distribution of soil organic matter and nutrients in a pear orchard. With the soil of the pear (cv. Dangshansu on P. betulifolia Bunge. rootstock) orchard under clean and sod cultivation models as test materials, the experiment was conducted to evaluate spatial variability of soil organic matter (SOM), total nitrogen (STN), total phosphorus (STP), total potassium (STK), available nitrogen (SAN), and available potassium (SAK) in and between rows at different soil depths (0–60 cm). The SOM, STN, STP, STK, SAN and SAK of the different soil layers under the two tillage models were different in the vertical direction. The SOM, STN, STP and SAN in the 0–20 cm soil layer were higher than those in the 20–40 and 40–60 cm soil layers. The STK of 40–60 cm soil layer was higher than that in the 0–20 and 20–40 cm soil layers. The STK increased with the depth of soil in the vertical direction in the clean cultivated pear orchard. Variability of the SOM, STN, STP, STK, SAN and SAK of sample sites in between rows of the same soil layer was found in the pear orchard soil in the horizontal direction under clean and sod cultivation management systems, except that STK of all sites did not show the difference in identical soil layers in the pear orchard under clean cultivation. The sod cultivation model improved the SOM, STN, and STK in the 0–20 cm soil layer in the pear orchard, and the three components increased by 12.8, 12.7 and 7.3% compared to clean cultivation, respectively. The results can be applicable to plan collection of orchard soil samples, assess orchard soil quality, and improve orchard soil management practices.

Temperature variation and solution treatment of high strength aluminum alloy were investigated with temperature data acquisition system, microstructural observation, mechanical properties test, electrical conductivity measurement and differential scanning calorimetry (DSC) analysis. Specimens with two dimensions were employed in the experiment. The results indicate that the specimens with large size undergo low solution temperature and short time, giving rise to the reduction of hardening precipitates. The optimized solution treatments for specimens with dimensions of 25 mm×25 mm×2.5 mm and 70 mm×60 mm×20 mm are (480 °C, 30 min) and (480 °C, 90 min), respectively. The densities of GP zones and η′ phases of the small specimen are higher than those of the large specimen, which is consistent with the properties of the alloys.

The effect of quenching rate on the electrical conductivity and microstructure of thick plates of incumbent AA7050 was investigated by employing Jominy end quench test. The electrical conductivity measurement and microstructural observation were conducted at different distances from the quenched end. The results indicate that the average cooling rates decrease with increasing the distance from the quenched end of the bar in the quench sensitive temperature range. However, the electrical conductivity increases with the increase of distance from the quenched end. The surface parts of the plate were fully recrystallized, while partial recrystallization took place at the quarter and center parts of the plate. The quench induced grain boundary precipitates became remarkably coarser and discontinuously distributed with increasing distance from the quenched end of the bar. Plenty of heterogeneous precipitates were observed to nucleate on Al3Zr dispersoids when the distance from the quenched end was greater than 38 mm.

The convection heat transfer characteristics of supercritical CO2 in a vertical circular tube of 2 mm inner diameter were investigated experimentally for pressures ranging from 78 to 95 bar, inlet temperatures from 25 to 40 °C, and inlet Reynolds numbers from 3800 to 20,000. The effects of the heat flux, thermo-physical properties, buoyancy and thermal acceleration on the convection heat transfer were analyzed. The experimental results show that for high inlet Reynolds numbers (e.g. Re = 9000) and high heat fluxes, a significant local deterioration and recovery of the heat transfer was found for upward flows but not for downward flows. Comparison of the experimental data for inlet Reynolds numbers from 3800 to 20,000 with some well-known empirical correlations showed large differences especially when the heat transfer deteriorates and then recovers when the effect of buoyancy is significant. The experimental data was used to develop modified local turbulent Nusselt number correlations for supercritical CO2 flowing in vertical small circular tubes.

In principle, every linear code can be used to construct a secret sharing scheme. However, in general, determining the access structure of the scheme is very hard. On the other hand, finding error correcting codes that produce secret sharing schemes with efficient access structures is also difficult. In this paper, we study a set of minimal codewords for certain classes of binary linear codes, and then determine the access structure of secret sharing schemes based on these codes. Furthermore, we prove that the secret sharing schemes obtained are democratic in the sense that every participant is involved in the same number of minimal access sets.

Dispersed flow film boiling heat transfer in vertical narrow annular gaps with gap sizes of 1.0, 1.5 and 2.0 mm was experimentally investigated with de-ionized water as the working fluid at low mass velocities. Comparisons of the experimental data with established correlations show that the correlations are not accurate for small gaps. The influences of the heating mode (only one tube heating or both tubes heated), the gap size and the tube diameter were analyzed. The data was correlated in the form of the Groeneveld equation with a modified wall temperature factor as use in the Polomik correlation and a modified gap size factor as use in the Yun and Muthu correlation. A new correlation was developed for dispersed flow film boiling heat transfer based on the experimental data for 1.0–2.0 mm gaps.

The gas-kinetic numerical algorithm solving the Boltzmann model equation is extended and developed to study the three-dimensional hypersonic flows of spacecraft re-entry into the atmosphere in perfect gas. In this study, the simplified velocity distribution function equation for various flow regimes is presented on the basis of the kinetic Boltzmann-Shakhov model. The discrete velocity ordinate technique and numerical quadrature methods, such as the Gauss quadrature formulas with the weight function 2/@p^1^/^2exp(-V^2) and the Gauss-Legendre numerical quadrature rule, are studied to resolve the barrier in simulating complex flows from low Mach numbers to hypersonic problems. Specially, the gas-kinetic finite-difference scheme is constructed for the computation of three-dimensional flow problems, which directly captures the time evolution of the molecular velocity distribution function. The gas-kinetic boundary conditions and numerical procedures are studied and implemented by directly acting on the velocity distribution function. The HPF (high performance fortran) parallel implementation technique for the gas-kinetic numerical method is developed and applied to study the hypersonic flows around three-dimensional complex bodies. The main purpose of the current research is to provide a way to extend the gas-kinetic numerical algorithm to the flow computation of three-dimensional complex hypersonic problems with high Mach numbers. To verify the current method and simulate gas transport phenomena covering various flow regimes, the three-dimensional hypersonic flows around sphere and spacecraft shape with different Knudsen numbers and Mach numbers are studied by HPF parallel computing. Excellent results have been obtained for all examples computed.

The microstructure of an AA 7B04 alloy in the form of plate was investigated using differential scanning calorimetry (DSC) and TEM analysis technologies. Tensile properties and electrical conductivity of AA 7B04 under various heat treatment conditions were also presented. The results reveal that peak-aged microstructure contains GP zones and η′ precipitates predominantly. After retrogressing and reaging(RRA), the η′ and η precipitates disperse in the alloy matrix, and the η precipitates distribute coarsely and sparsely, decorating the grain boundaries, together with precipitate free zones(PFZs) around them. It is also shown that selecting of suitable heat treatments can provide optimal precipitates in matrix and at grain boundaries, which gives rise to a combination of high strength and stress corrosion cracking(SCC) resistance in such materials.

A calculation of band structure is carried out and demonstrates that a hollow spherical non-closed-packed face-centered cubic uniaxial structure possesses a robust complete photonic band gap between the low-frequency bands (2nd and 3rd bands). The results show that the relative gap size can reach a value of 6.1% at a low dielectric contrast of 7.84 appropriate to the transparent TiO2. The influence of structure variations on the band gap, such as hollow spheres, cylindrical tubes and dielectric contrast, is also discussed.

High-performance titania inverse opal films have been derived from a sol–gel procedure using polystyrene colloidal crystals as templates. By carefully controlling the synthetic procedures, the titania inverse opal films display a uniform color over centimeter dimensions. Scanning electron microscopy is employed to characterize the qualities of the titania inverse opal films. Electron diffraction pattern shows a polycrystalline anatase structure of TiO2.

We discuss the relationships among several types of fuzzy automata in which all fuzzy sets are defined by membership functions whose codomains are a lattice-ordered monoid L. These automata include nondeterministic L-valued finite automata with @L-move, nondeterministic L-valued finite automata, deterministic L-valued finite automata, and L-valued finite-state automata. We consider all that come with fuzzy initial states and fuzzy final states or with crisp initial states or crisp final states. Some comparative results concerning the power of fuzzy automata used in the existing literature to recognize fuzzy languages are given systematically.

Based on the Boltzmann–BGK model equation, the unified simplified velocity distribution function equation adapted to various flow regimes can be presented by the aid of the basic characteristic on molecular movement and collision approaching to equilibrium. The optimum Golden Section principle is extended and applied to the discrete velocity ordinate method in order to discretize the corresponding velocity components, and then the molecular velocity distribution function equation will be cast into hyperbolic conservation laws form with non-linear source terms. In view of the unsteady characteristic of molecular convective movement and colliding relaxation, the time-splitting method is applied to decompose the velocity distribution function equations into the colliding relaxation equations with non-linear source terms and the convective motion equations. Based on the second-order Runge–Kutta method and the non-oscillatory, containing no free parameters, and dissipative (NND) finite difference method, the gas kinetic finite difference second-order scheme is constructed to directly solve the discrete velocity distribution functions. Four types of discrete velocity quadrature rules, such as the modified Gauss–Hermite formula and the Golden Section number-theoretic integral method, are developed and applied to evaluate the macroscopic flow moments of the distribution functions over the velocity space. As a result, a unified gas kinetic algorithm is established for the flows from rarefied transition to continuum regime. To test the reliability of the present method, the one-dimensional shock wave structures, the flows past two-dimensional circular cylinder and the three-dimensional flows over sphere with various Knudsen numbers are simulated. The computational results are found in high resolution of the flow fields and good agreement with the theoretical, DSMC, and experimental results.

It is proved that the category Top of topological spaces is a mono-reflective and epi-coreflective subcategory of fuzzy topological spaces in the sense of Hutton.