Comparative analysis of classical models (MARS3D, AZOV3D) and lattice Boltzmann models for shallow water hydrodynamics computations

Different numerical approaches of hydrodynamics of shallow water basins are considered and compared. Two approaches are developped in TIT-Russia: one of them is classical and based on numerical solution of the Navier-Stokes equations by Pressure-Correction method, another (developed several years ago) is  based on the solution of the Lattice Boltzmann kinetic equation. The comparative analysis of these two approaches with MARS3D is performed for a shallow water basin example: «Etang de Berre»

Frost resistance of cement-sand and concrete beams during unilateral freezing

The work investigates changes in the beam structure under the action of local freezing, which leads to a change of the mechanical properties of the material and, consequently, of the beam structure. Two types of beam samples were used: from cement-sand mortar and from concrete. The work investigates the change in the development of deformations depending on the conditions of freezing of samples. The second accelerated method for assessing frost resistance was chosen according to DSTU B В.2.7-47-96. An accelerated method was chosen for assessing frost resistance at the temperature of -20 ±2 C°. After every five freeze-thaw cycles, the following changes were monitored: mass, water absorption, ultrasound transmission rate, damage coefficient, tensile bending strength, splitting strength, compressive strength, carbonization depth. The results showed that both in concrete and in mortar samples, the compressive strength after freezing was lower by 8% and 15% accordingly. The experimental results obtained confirm the assumptions made that the frost resistance of the material depends on the conditions of exposure of negative temperatures on products and structures and it can be used in a wider range of construction which will push regional development

Frost resistance of cement-sand and concrete beams during unilateral freezing

The work investigates changes in the beam structure under the action of local freezing, which leads to a change of the mechanical properties of the material and, consequently, of the beam structure. Two types of beam samples were used: from cement-sand mortar and from concrete. The work investigates the change in the development of deformations depending on the conditions of freezing of samples. The second accelerated method for assessing frost resistance was chosen according to DSTU B В.2.7-47-96. An accelerated method was chosen for assessing frost resistance at the temperature of -20 ±2 C°. After every five freeze-thaw cycles, the following changes were monitored: mass, water absorption, ultrasound transmission rate, damage coefficient, tensile bending strength, splitting strength, compressive strength, carbonization depth. The results showed that both in concrete and in mortar samples, the compressive strength after freezing was lower by 8% and 15% accordingly. The experimental results obtained confirm the assumptions made that the frost resistance of the material depends on the conditions of exposure of negative temperatures on products and structures and it can be used in a wider range of construction which will push regional development

Development of algorithms for assessing risks and vulnerability to anthropogenic impacts

The paper presents currently used approaches to the assessment of water pollution by various types of pollutants. Based on the existing criteria, an algorithm for assessing risks and vulnerability to anthropogenic impacts is proposed. The software package obtained on their basis makes it possible to model the processes of the spread of pollutants in the studied water area, to detect and evaluate the power of sources of pollutants and manage them, to assess risks and vulnerabilities in relation to anthropogenic impacts, to carry out zoning of the water area of a shallow water body in accordance with the levels of anthropogenic loads, to carry out environmental design from the standpoint of sustainable development

Optimization of the amount of transmitted data in parallel algorithms for iterative methods with a triangular preconditioner

Software has been developed in the C++ programming language using the MPI parallel programming technology, designed for mathematical modeling of the transport of substances in coastal systems. When calculating the dynamics of the spread of a pollutant, the decomposition of the computational domain was carried out to organize the computational process on a multiprocessor computer system K-60 in KIAM RAS. To solve the system of grid equations obtained as a result of the approximation of the problem, iterative methods were used, with a triangular preconditioner

Solving Grid Equations Using the Alternating-triangular Method on a Graphics Accelerator

The paper describes a parallel-pipeline implementation of solving grid equations using the modified alternating-triangular iterative method (MATM), obtained by numerically solving the equations of mathematical physics. The greatest computational costs at using this method are on the stages of solving a system of linear algebraic equations (SLAE) with lower triangular and upper non-triangular matrices. An algorithm for solving the SLAE with a lower triangular matrix on a graphics accelerator using NVIDIA CUDA technology is presented. To implement the parallel-pipeline method, a three-dimensional decomposition of the computational domain was used. It is divided into blocks along the y coordinate, the number of which corresponds to the number of GPU streaming multiprocessors involved in the calculations. In turn, the blocks are divided into fragments according to two spatial coordinates — x and z. The presented graph model describes the relationship between adjacent fragments of the computational grid and the pipeline calculation process. Based on the results of computational experiments, a regression model was obtained that describes the dependence of the time for calculation one MATM step on the GPU, the acceleration and efficiency for SLAE solution with a lower triangular matrix by the parallel-pipeline method on the GPU were calculated using the different number of streaming multiprocessors.The paper describes a parallel-pipeline implementation of solving grid equations using the modified alternating-triangular iterative method (MATM), obtained by numerically solving the equations of mathematical physics. The greatest computational costs at using this method are on the stages of solving a system of linear algebraic equations (SLAE) with lower triangular and upper non-triangular matrices. An algorithm for solving the SLAE with a lower triangular matrix on a graphics accelerator using NVIDIA CUDA technology is presented. To implement the parallel-pipeline method, a three-dimensional decomposition of the computational domain was used. It is divided into blocks along the y coordinate, the number of which corresponds to the number of GPU streaming multiprocessors involved in the calculations. In turn, the blocks are divided into fragments according to two spatial coordinates — x and z. The presented graph model describes the relationship between adjacent fragments of the computational grid and the pipeline calculation process. Based on the results of computational experiments, a regression model was obtained that describes the dependence of the time for calculation one MATM step on the GPU, the acceleration and efficiency for SLAE solution with a lower triangular matrix by the parallel-pipeline method on the GPU were calculated using the different number of streaming multiprocessors

A software package for solving grid equations in areas with geometry "stretched" along one of the spatial directions

A method for solving grid equations in areas with geometry "stretched" along one of the spatial directions is proposed. Method proposed for model includes pollutants whose concentration in the Azov Sea, according to the analysis of scientific publications and environmental databases, exceeds the maximum permissible concentration (MPC). The mechanism of the preconditioner formation is described. The estimation of the minimum and maximum eigenvalues is performed. Using object-oriented analysis and design, a class library has been implemented to solve the problem of impurity propagation in a shallow reservoir. The architecture of an information system to support scientific research capable of functioning in conditions of using heterogeneous computing environments is described. The system is based on the requirement of the maximum possible use of free software in order to minimize capital and operational costs. The system uses classes that allow you to read and write information about the geometry of the object under study and the parameters of the calculated grid. Numerical experiments were carried out using the developed software package, including the proposed mathematical model, focused on the multiprocessor computing system (MCS). The dependences of the SLAE solution time on the number of diagonals and the order of the matrix are obtained. The number of iterations for solving grid equations has been experimentally determined depending on the ratio of the number of nodes in spatial coordinates

Vascular Endothelial Growth Factor in Anterior Chamber Liquid Patients with Diabetic Retinopathy, Cataract and Neovascular Glaucoma

INTRODUCTION: The aims of this study were: (1) to investigate the association of vascular endothelial growth factor isoform A (VEGF-A) concentration in the anterior chamber liquid (ACL) with vascular proliferation in patients with diabetic retinopathy (DR) who had undergone surgical treatment for cataract and neovascular glaucoma; (2) to analyze the association of VEGF-A level in ACL with the cataract surgery outcomes. MATERIALS AND METHODS: Undiluted aqueous fluid samples were obtained from 207 eyes of patients who underwent intraocular surgery, 136 patients with diabetes mellitus (DM) and 22 patients without DM. The ACL samples were obtained during operation. The VEGF-A levels were analyzed by enzyme-linked immunosorbent assay. RESULTS: The lowest VEGF-A levels were in diabetic patients without signs of DR [22.75 pg/mL (10.78; 63.36)]. More severe DR tended to occur in diabetic patients with higher VEGF-A levels in ACL. In diabetic patients with proliferative DR (PDR), VEGF-A levels were significantly higher [336.6 pg/mL (232.3; 410.74)] than in patients without DR P < 0.0001. In patients with terminal stage of DR [neovascular glaucoma (NG)], VEGF-A levels were dramatically higher and attained 1,634.01 pg/mL (610.69; 2657.33). In non-diabetic patients, VEGF-A levels were 95.07 pg/ml (60.92; 129.22). The best visual acuity results in post-operative period were observed in the group of diabetic patients without DR. In the group of patients with PDR, post-operative visual acuity [0.26 (0.1; 0.42)] was similar to visual acuity before operation [0.29 (0.13; 0.44)]. There was no significant increase in visual acuity due to cataract surgery. In 52.4% patients, no complications had occurred by the end of the follow-up period. In 40% patients, retinal laser coagulation was performed, and in 7.6% patients NG had developed. CONCLUSION: VEGF-A level in ACL increases with DR progression and may be of prognostic value in evaluating the potential risk of further neovascularization progression in diabetic patients

Synthesis of Amphiphilic Copolymers of N-Vinyl-2-pyrrolidone and Allyl Glycidyl Ether for Co-Delivery of Doxorubicin and Paclitaxel

Co-delivery of chemotherapeutics in cancer treatment has been proven essential for overcoming multidrug resistance and improving the outcome of therapy. We report the synthesis of amphiphilic copolymers of N-vinyl-2-pyrrolidone and allyl glycidyl ether of various compositions and demonstrate that they can form nanoaggregates capable of simultaneous covalent immobilization of doxorubicin by the epoxy groups in the shell and hydrophobic-driven incorporation of paclitaxel into the core of nanoparticles. The structure of the obtained copolymers was characterized by (13)C NMR, IR, and MALDI spectroscopy, as well as adsorption at the water/toluene interface. A linear increase in the number-average molecular weight of amphiphilic copolymers and a decrease in the number-average diameter of macromolecular aggregates with an increase in the ratio N-vinyl-2-pyrrolidone/allyl glycidyl ether were observed. The assembled nanocarriers were characterized by DLS. The reported novel nanocarriers can be of interest for delivery and co-delivery of a wide range of pharmacological preparations and combined therapy for cancer and other deceases