Environmental flows for the Yangtze Estuary based on salinity objectives

Environmental flows based on the salinity objectives for China’s Yangtze Estuary were quantified to assess the impacts of changing freshwater inflow on the estuarine ecosystem. The salinity objectives for three benthos habitats in the Yangtze Estuary were studied to determine their requirements during the most critical period of the year. The temporal variation in the natural monthly river discharge represented the temporal variation of the ecological objectives used to maintain natural flow regimes. A numerical model, coupled a hydrodynamic processes model with a salinity model and validated using field data of tidal height, current velocity, and salinity at different stations, was developed to simulate the spatial distribution of salinity as a function of the variation in freshwater inflows. The prediction results of the proposed model agreed well with the field data. Considering the salinity objectives for the different habitats, the environmental flow requirements for the Yangtze Estuary were determined. Annual environmental flows should be 9.63 × 10¹¹, 6.32 × 10¹¹, and 4.70 × 10¹¹ m³ for the high, medium, and minimum objectives, which are equivalent to 104%, 68%, and 50% of the annual river discharge, respectively. The periods from September to November should be considered as the critical seasons to maintain the minimum environmental flows in the Yangtze Estuary.     

Environmental flow requirements for integrated water resources allocation in the Yellow River Basin,China

Based on the classification and regionalization of the ecosystem, multiple ecological management objectives and the spatial variability of the environmental flow requirements of the Yellow River Basin were analyzed in this study. The summation rule was used to calculate water consumption requirements and the compatibility rule, i.e., “maximum” principle, was also adopted to estimate the non-consumptive use of water in the river basin. The environmental flow requirements for integrated water resources allocation were determined by identifying the natural and artificial water consumption in the Yellow River Basin. The results indicated that the annual minimum environmental flow requirements amounted to 317.62 × 10⁸ m³, which represented 54.76% of the natural river flows, while for the environmental flow requirements for the integrated water resources allocation were 262.47 × 10⁸ m³, which represented 45.25% of the natural river flows. The highest percentage of environmental flow requirements was 93.64% for the river ecosystem. It can be concluded that the primary concerns should be put on the downstream river water requirements to determine the environmental flows for integrated water resources allocation in a river basin.     

Vacuum polarization in light two-electron atoms and ions

A general theory of the vacuum polarization in light atomic and muon-atomic systems is considered. We derive the closed analytical expression for the Uehling potential and evaluate corrections on vacuum polarization for the 1¹S-state of the two-electron ³He and ⁴He atoms and for some two-electron ions, including the Li⁺, Be²⁺, B³⁺ and C⁴⁺ ions. The correction for vacuum polarization in two-electron He atoms has been evaluated as ΔE_ueh ≈ 7.253 ± 0.0025 × 10⁻⁷ a.u. The analogous corrections in the two-electron He-like ions rapidly increase with the nuclear charge Q (ΔE_ueh ≈ 2.7061 × 10⁻⁶ a.u. for the Li⁺ ion and ΔE_ueh ≈ 2.3495 × 10⁻⁵ a.u. for the C⁴⁺ ion). The corresponding corrections have also been evaluated for the electron–nucleus and electron–electron interactions.     

Effects of CO2 concentration and moisture content of sugar-free media on the tissue-cultured plantlets in a large growth chamber

The dynamic fluctuations of CO₂ concentration in the tissue culture growth chamber after transplantation of petunia, chrysanthemum and tomato plantlets were recorded with a real-time control system to determine the critical CO₂ concentration levels of 35 μl l^?1 at which CO₂ enrichment is needed. The experimental data showed that the tissue-cultured plantlets of petunia, chrysanthemum and tomato had the same CO₂ concentration dynamics. The results indicated that CO₂ enrichment was proper on the second day after transplantation. Petunia plantlets were used to conduct experiments under PPFD of 80 μmol m^?2 s^?1, and CO₂ concentrations of 350 ± 50 μl l^?1, 650 ± 50 μl l^?1 and 950 ± 50 μl l^?1 as well as medium moisture contents of 60%, 70% and 80%, with the result that plantlets grew better under CO₂ concentration of 650 ± 50 μl l^?1 than under the other two concentrations with all the different media water contents. Three media water contents under the same CO₂ concentration produced plantlets with the same quality. The impacts of CO₂ concentrations on plantlets are more important than those of the media water contents. Sugar-free tissue culture, as compared with the conventional culture, showed that CO₂ enrichment to 350 ± 50 μl l^?1 can promote the growth of the cultured plantlets. Sugar-free tissue culture produced healthy plantlets with thick roots, almost equivalent to the common plantlets.     

Space–time symmetry violation,configuration mixing model and E-infinity theory

We have studied the time reversal symmetry violation on the bases of the configuration mixing model and E-infinity theory. With the use of the Cabibbo angle approximation, we have presented the transformation matrix in terms of the golden ratio (?), and shown that the time reversal symmetry violation is described by the configuration mixing of the unstable and stable manifolds (W^u, W^s). The magnitude of the mixing for the weak interaction field is given by the expression sin² θ_T(theor) ≈ sin⁴ θ_C(theor) ≈ (?)¹² = 3.105 × 10^?3, which is compared to the Kaon decay experiment ～2.3 × 10^?3. We have also discussed the space–time symmetry violation by using the CPT theorem.     

Neural networks analysis of free laminar convection heat transfer in a partitioned enclosure

The feasibility of using neural networks (NNs) to predict the complete thermal and flow variables throughout a complicated domain, due to free convection, is demonstrated. Attention is focused on steady, laminar, two-dimensional, natural convective flow within a partitioned cavity. The objective is to use NN (trained on a database generated by a CFD analysis of the problem of a partitioned enclosure) to predict new cases; thus saving effort and computation time. Three types of NN are evaluated, namely General Regression NNs, Polynomial NNs, and a versatile design of Backpropagation neural networks. An important aspect of the study was optimizing network architecture in order to achieve best performance. For each of the three different NN architectures evaluated, parametric studies were performed to determine network parameters that best predict the flow variables.A CFD simulation software was used to generate a database that covered the range of Rayleigh number Ra = 10⁴–5 × 10⁶. The software was used to calculate the temperature, the pressure, and the horizontal and vertical components of flow speed. The results of the CFD were used for training and testing the neural networks (NN). The robustness of the trained NNs was tested by applying them to a “production” data set (1500 patterns for Ra = 8 × 10⁴ and 1500 patterns for Ra = 3 × 10⁶), which the networks have never been “seen” before. The results of applying the technique on the “production” data set show excellent prediction when the NNs are properly designed. The success of the NN in accurately predicting free convection in partitioned enclosures should help reduce analysis-time and effort. Neural networks could potentially help solve some cases in which CFD fails to solve because of numerical instability.     

Fast Rectangular Matrix Multiplication and Applications

First we study asymptotically fast algorithms for rectangular matrix multiplication. We begin with new algorithms for multiplication of ann×nmatrix by ann×n²matrix in arithmetic timeO(n^ω),ω=3.333953…, which is less by 0.041 than the previous record 3.375477…. Then we present fast multiplication algorithms for matrix pairs of arbitrary dimensions, estimate the asymptotic running time as a function of the dimensions, and optimize the exponents of the complexity estimates. For a large class of input matrix pairs, we improve the known exponents. Finally we show three applications of our results:   (a) we decrease from 2.851 to 2.837 the known exponent of the work bounds for fast deterministic (NC) parallel evaluation of the determinant, the characteristic polynomial, and the inverse of ann×nmatrix, as well as for the solution to a nonsingular linear system ofnequations,   (b) we asymptotically accelerate the known sequential algorithms for the univariate polynomial composition mod xⁿ, yielding the complexity boundO(n^1.667) versus the old record ofO(n^1.688), and for the univariate polynomial factorization over a finite field, and   (c) we improve slightly the known complexity estimates for computing basic solutions to the linear programming problem withmconstraints andnvariables.     

Computational modelling of fluid structure interaction at nano-scale boundaries with modified Maxwellian velocity distribution

The soft collisions among fluid–fluid and fluid-wall molecules are modeled from first principles. In particular, the assumption of Maxwellian distribution of velocities for thermalized molecules, in both parallel and perpendicular directions to the wall, has been re-evaluated with supporting experimental and/or numerical evidence.It is proposed that the normal component of molecular velocity post collision is conserved for all fluid molecules. The slip effect at the wall boundary, introduced by the surface roughness, is accounted by an accommodation coefficient f. A moving least square method is used to calculate macroscopic velocity values. The influence of molecular interaction on the macroscopic velocity distribution is investigated at 40 MPa and 300 K for slit pore, inclined and stepped wall configurations. The accommodation coefficient values f = 0, 0.07, 0.257, 0.45, 0.681 and 1; and acceleration values ranging from zero to 1 × 10¹¹ m/s² and 250 × 10¹¹ m/s² are used for comparison.The distribution of macroscopic velocity parallel to the wall is studied to observe the effect of the slip behaviour. The detailed study of average of velocity values at various magnitudes of acceleration has shown an evidence of characteristic low and high speed of molecular flows that is considered as significant and a comparison is sought with an equivalent laminar and turbulent flow style behaviour. The two dimensional vector and contour plots of macroscopic velocity provide further insights in understanding Continuum velocity distributions resulting from molecular fluid-wall interaction at nanoscale. The research has highlighted the need to develop molecular dynamics simulation techniques for non-periodic boundary conditions.     

GIS-based optimization for the locations of sewage treatment plants and sewage outfalls – A case study of Nansha District in Guangzhou City,China

Based on GIS technology, eco-suitability evaluation method integrating economic, social and ecological factors is employed to optimize the locations of the sewage treatment plants and outfalls in this paper. The ecological indices considering eco-sensitivity areas as key elements of the integrated evaluation system are allotted to the water subsystem, riparian zone subsystem, and land subsystem. A novel integrated eco-suitability evaluation index system encompassing ten criteria and fifteen indices is established to generate the distributed eco-suitability map of the concerned areas and determine the possible locations of sewage treatment plants and sewage outfalls according to the eco-suitability levels. With the case study of Nansha District in Guangzhou City, China, 212 km² areas of land are found to be suitable for locating the sewage treatment plants, 87 km² areas of water suitable for sewage release, and 6 km² area of riparian zone unsuitable for sewage outfalls.     

An image encryption scheme based on rotation matrix bit-level permutation and block diffusion

This paper proposes a novel image encryption scheme based on rotation matrix bit-level permutation and block diffusion. Firstly, divide plain image into non-overlapping 8 × 8 pixels blocks with a random matrix, then transform each block into an 8 × 8 × 8 three-dimensional (3-D) binary matrix, which has six directions just as a cube. Permutation is performed by multiplying the 3-D matrix by the rotation matrix that relies on plain image according to different direction. Secondly, use block diffusion to further change the statistical characteristics of the image after confusion. Experiment results and analysis show that the scheme can not only achieve a satisfactory security performance, but also have the suitability for a parallel mode and the robustness against noise in communication system.     

Identification of the ten inertia parameters of a rigid body

A special antisymmetric 4 × 4 matrix form of the equation of motion of a rigid body is proposed. This form depends linearly on the symmetric (4 × 4)-matrix of the Fayet global inertia tensor, containing the ten inertia parameters of a rigid body (the mass, the three coordinates of the centre of mass and the six components of the classical inertia tensor). For identifying the global inertia tensor, an algorithm is proposed which is based on the method of least squares and the method of conjugate gradients and tested using the example of a rigid body, the motion of which is obtained by computer modelling.     

Dynamic modelling of dissolved oxygen in the creeks of Sagar island,Hooghly–Matla estuarine system,West Bengal,India

Hooghly–Matla estuarine ecosystem is one of the largest estuarine ecosystems of the world. Sagar island is the largest delta in this estuarine complex. This island is criss-crossed by small and large creeks with mangrove vegetation and all are connected to the principal estuarine water. Decomposition of mangrove litter in soil is major source of inorganic nutrient to phytoplankton of the adjacent creeks. Deforestation of mangrove affects the primary production, which in turn reduces the availability of dissolved oxygen for the organisms residing in the estuary. Considering the importance of dissolved oxygen in various aspects of aquatic life, a dynamic model of dissolved oxygen at Sagar island of Hooghly–Matla estuarine complex with the help of single dimension differential equation is proposed in the present paper. Different physical, chemical and biological factors such as solar irradiance, temperature, salinity of water, particulate organic matter, re-aeration, wind velocity, phytoplankton and zooplankton, which control the fluctuation of dissolved oxygen, are included in the present model. Most of the parameter values are collected directly from the field surveys. The parameter values which are not able to collect from the field, obtained from literatures are calibrated. To make the model realistic it is properly validated with observed data and to know the statistical significance, chi square goodness fit test is performed. Field surveys are performed over two years. During calibration and validation, two sets of data (first year and second year data) are used. Chi-square values are 5.97 and 6.17 for first and second sets of data respectively (p < 0.05). Sensitivity analysis reveals that optimal light intensity is the most sensitive parameter for dissolved oxygen dynamics. Results also show that wind velocity, solar irradiation, salinity of water and temperature are important factors for controlling the dynamics of dissolved oxygen. Macrophytes have very little contribution to oxygen production in the creeks of Sagar island. Model reveals that low dissolved oxygen in the creek water is one of the causes of decline in fish population of the estuary.     

On tropical matrices of small factor rank

The notion of the factor rank of tropical matrices is considered. We construct a linear-time algorithm that either finds a full-rank 3 × 3 submatrix of a given matrix A or concludes that the factor rank of A is less than 3. We show that there exist matrices of factor rank 4 whose 4 × 4 submatrices are all rank deficient.     

Equivalent Blocks of Finite General Linear Groups in Non-describing Characteristic

J. Chuang, R. Kessar, and J. Rickard have proved Broué's Abelian defect group conjecture for many symmetric groups. We adapt the ideas of Kessar and Chuang towards finite general linear groups (represented over non-describing characteristic). We then describe Morita equivalences between certain p-blocks of GL_n(q) with defect group C_p^α × C_p^α, as q varies (see Theorem 2). Here p and q are coprime. This generalizes work of S. Koshitani and M. Hyoue, who proved the same result for principal blocks of GL_n(q) when p = 3, α = 1, in a different way.     

Modeling and numerical simulation of the resistance spot welding of zinc coated steel sheets using rounded tip electrode: Analysis of required conditions

This paper investigates the essential conditions to improve the accuracy of a resistance spot welding computational study of advanced zinc coated steel sheets using rounded tip electrode. An experimental analysis is performed to highlight the required considerations for a suitable simulation. A sequential Electrical-Thermal-Metallurgical and Mechanical (ETMM) finite element analysis with appropriate precautions of the contact conditions enables to accurately simulate the nugget development during the welding. A critical smooth evolution of the contact radius is required. A fine meshing with an interfacial mesh size of at least 0.05 × 10⁻³ m combined with a coupling time step of 0.0025 s between the electrical-thermal-metallurgical and the mechanical analysis allows a regular incrementation of the contact radius, without burdening the time computing. Accurate values of the contact resistance depending on the interfacial pressure and temperature are essential for a good simulation of the nugget size. The ETMM calculation is successfully extended to the simulation of the welding of a typical two sheets assembly.     

Anytime anyspace probabilistic inference

This paper investigates methods that balance time and space constraints against the quality of Bayesian network inferences––we explore the three-dimensional spectrum of “time × space × quality” trade-offs. The main result of our investigation is the adaptive conditioning algorithm, an inference algorithm that works by dividing a Bayesian network into sub-networks and processing each sub-network with a combination of exact and anytime strategies. The algorithm seeks a balanced synthesis of probabilistic techniques for bounded systems. Adaptive conditioning can produce inferences in situations that defy existing algorithms, and is particularly suited as a component of bounded agents and embedded devices.     

Commutativity and self-duality: Two tales of one equation

The mathematical expressions for the commutativity or self-duality of an increasing [0, 1]² → [0, 1] function F involve the transposition of its arguments. We unite both properties in a single functional equation. The solutions of this functional equation are discussed. Special attention goes to the geometrical construction of these solutions and their characterization in terms of contour lines. Furthermore, it is shown how ‘rotating’ the arguments of F allows to convert the results into properties for [0, 1]² → [0, 1] functions having monotone partial functions.     

Simulación numérica del flujo turbulento de aire con gotas dispersas de agua a través de separadores de torres de refrigeración

This work presents a numerical study on the turbulent flow of air with dispersed water droplets in separators of mechanical cooling towers. The averaged Navier-Stokes equations are discretised through a finite volume method, using the Fluent and Phoenics codes, and alternatively employing the turbulence models k ? ?, k ? ω and the Reynolds stress model, with low-Re version and wall enhanced treatment refinements. The results obtained are compared with numerical and experimental results taken from the literature. The degree of accuracy obtained with each of the considered models of turbulence is stated. The influence of considering whether or not the simulation of the turbulent dispersion of droplets is analyzed, as well as the effects of other relevant parameters on the collection efficiency and the coefficient of pressure drop. Focusing on four specific eliminators (‘Belgian wave’, ‘H1-V’, ‘L-shaped’ and ‘Zig-zag’), the following ranges of parameters are outlined: 1 ≤ U_e ≤ 5 m/s for the entrance velocity, 2 ≤ D_p ≤ 50 μm for the droplet diameter, 650 ≤ Re ≤ 8.500 for Reynolds number, and 0.05 ≤ P_i ≤ 5 for the inertial parameter. Results reached alternately with Fluent and Phoenics codes are compared. The best results correspond to the simulations performed with Fluent, using the SST k ? ω turbulence model, with values of the dimensionless scaled distance to wall y⁺ in the range 0.2 to 0.5. Finally, correlations are presented to predict the conditions for maximum collection efficiency (100 %), depending on the geometric parameter of removal efficiency of each of the separators, which is introduced in this work.     

Modelación numérica de deslizamientos de ladera en embalses mediante el Método de Partículas y Elementos Finitos (PFEM)

The paper presents the results of the application of the Particle Finite Element Method (PFEM) to the analysis of landslides in reservoirs. This is a complex phenomenon, because of the interaction between the landslide, the still water in the reservoir and the dam. PFEM combines a Lagrangian approach with the solution of the governing equations of the problem using the FEM. A mesh connecting the initial set of particles (nodes) is re-generated in every time step. Some validation cases are presented, in which PFEM results are compared with experimental data. More complex calculations have been made over the actual geometry of reservoirs taken from the cartographic information of the sites. In these cases the wave generation, its propagation and dam overtopping are reproduced. Finally, Lituya bay rock slide in which 90 × 10⁶ tons of rocks fell on the bay, generating a huge wave that caused a maximum run-up of 524 m on the opposite shore, has been simulated in 3D. The results show that PFEM is a useful tool in risk assessment related with landslides in reservoirs as it gives a good approximation to the potential affections, thus allowing the appropriate design of protection measures.     

A generalized AKNS hierarchy,bi-Hamiltonian structure,and Darboux transformation

A new generalized AKNS hierarchy is presented starting from a 4 × 4 matrix spectral problem with four potentials. Its generalized bi-Hamiltonian structure is also investigated by using the trace identity. Moreover, the special coupled nonlinear equation, the coupled KdV equation, the KdV equation, the coupled mKdV equation and the mKdV equation are produced from the generalized AKNS hierarchy. Most importantly, a Darboux transformation for the generalized AKNS hierarchy is established with the aid of the gauge transformation between the corresponding 4 × 4 matrix spectral problem, by which multiple soliton solutions of the generalized AKNS hierarchy are obtained. As a reduction, a Darboux transformation of the mKdV equation and its new analytical positon, negaton and complexiton solutions are given.