Hrachya Astsatryan

An interoperable cloud-based scientific GATEWAY for NDVI time series analysis

Processing of high-resolution time series satellite images typically requires a large amount of computational resources and time. We introduce here a scientific gateway for computing the Normalized Difference Vegetation Index (NDVI) time series data. Based on a distributed workflow using the Web Processing Service (WPS) standard, the gateway aims to be completely interoperable with other standardized tools. The availability of this gateway may help researchers to acquire knowledge of land cover changes more efficiently over very large spatial and temporal extents, which is especially important in the context of Armenia for which timely decision-making is needed. A scientific gateway for computing the NDVI time series data based on a distributed workflow using the WPS standard.An optimal NDVI times series geoprocessing services based on cloud infrastructures.Experimental results in the study area that include some part of the territory of Armenia.

Web Portal for Photonic Technologies Using Grid Infrastructures

The modeling of physical processes is an integral part of scientific and technical research. In this area, the Extendible C++ Application in Quantum Technologies (ECAQT) package provides the numerical simulations and modeling of complex quantum systems in the presence of decoherence with wide applications in photonics. It allows creating models of interacting complex systems and simulates their time evolution with a number of available time-evolution drivers. Physical simulations require massive amounts of calculations are often executed on distributed computing infrastructures. It is often difficult for non expert users to use such computational infrastructures or even to use advanced libraries over the infrastructures, because they often require being familiar with middleware and tools, parallel programming techniques and packages. The Parallel Grid Run-time and Application Development Environment (P-RADE) Grid Portal is a Grid portal solution that allows users to manage the whole life-cycle for executing a parallel application on the computing Grid infrastructures. The article describes the functionality and the structure of the web portal based on ECAQT package.

A Grid-Aware Web Portal with Advanced Service Trading for Linear Algebra Calculations

Due to the rapid growth of the Internet, there has been a rising interest in using the Web as an interface to develop various applications over computational Grid environments. The purpose of this work is to develop a Grid-aware Web interface for linear algebra tasks with advanced service trading. Developing efficient and portable codes, requires users to face parallel computing and programming and to make use of different standard libraries, such as the BLAS [1], LAPACK [2] and ScaLAPACK [3] in order to solve computational tasks related to linear algebra. For this purpose, a scientific computing environment based on a Web interface is described that allows users to perform their linear algebra tasks without explicitly calling the above mentioned libraries and softwarep tools, as well as without installing any piece of software on local computers: users enter algebraic formula (such as in Matlab or Scilab [4]) that are evaluated for determining the combinations of services answering the user request. Services are then executed locally or over the Grid using the Distributed Interactive Engineering Toolbox (DIET) [5] middleware.

On the Easy Use of Scientific Computing Services for Large Scale Linear Algebra and Parallel Decision Making with the P-Grade Portal

Scientific research is becoming increasingly dependent on the large-scale analysis of data using distributed computing infrastructures (Grid, cloud, GPU, etc.). Scientific computing (Petitet et al. 1999) aims at constructing mathematical models and numerical solution techniques for solving problems arising in science and engineering. In this paper, we describe the services of an integrated portal based on the P-Grade (Parallel Grid Run-time and Application Development Environment) portal (http://www.p-grade.hu) that enables the solution of large-scale linear systems of equations using direct solvers, makes easier the use of parallel block iterative algorithm and provides an interface for parallel decision making algorithms. The ultimate goal is to develop a single sign on integrated multi-service environment providing an easy access to different kind of mathematical calculations and algorithms to be performed on hybrid distributed computing infrastructures combining the benefits of large clusters, Grid or cloud, when needed.

SWAT hydrological model as a DaaS cloud service

Earth Science community depends on the exploration, analysis and reprocessing of high volumes of data as well as the modeling and simulation of complex coupled systems on multiple scales. The main aim of this article is to introduce a new hydrological modeling service based on the Soil and Water Assessment Tool (SWAT) (Arnold et al. J American Water Resour Assoc 34(1), 73–89, 1998 ; Arnold and Fohrer Hydrol Process 19(3), 563–572, 2005) model using high efficiency, resource sharing and low cost cloud computing resources (Astsatryan et al. International Journal of Scientific & Engineering Research 1(1), 1130–1133, 2014). Such a Desktop as a Service (DaaS) approach allowing users to work from anywhere, and gives centralized desktop management and great performance. Within the Spatial Data Infrastructure (SDI) and cloud platform, the DaaS service gives secure access to the model and a centralized data storage to get a SWAT model input. The article illustrates the analyses of the implementation of the SWAT model for the Sotk watershed of Lake Sevan in Armenia (Sargsyan 2007).

An interoperable web portal for parallel geoprocessing of satellite image vegetation indices

The main objective of this paper is to introduce a portal of geoprocessing services that can be used to compute either a single vegetation index or a combination of vegetation indices, as a workflow. High Performance Computing (HPC) resources are used for the calculations, and the Web Processing Service (WPS) standard is used to handle the requests from and the responses to the portal. In case of a workflow, a single node of the cluster is dedicated to each index, and the number of used cores depends on the complexity of the task. In addition, based on a series of experiments made to accelerate remote sensing image processing, a parallelization method within the computational node is automatically chosen depending on the complexity of the operations and the amount of data. The suggested algorithm optimizes the processing by selecting the best methodology (serial or parallel) and the number of cores to efficiently manipulate and distribute the data. The interoperable web portal, Spatial Data Infrastructure (SDI) and the heterogeneous resources of HPC cluster are located in the same local area network, and the cluster nodes have access to the data via network file system sharing. The use of standardized web services makes it possible to use remote data as inputs.

Introduction of a Grid-aware portlet for numerical calculations

Grid portals are one of the most popular user interfaces to Grids. Grid portals build upon the familiar Web portal model offer to virtual communities of users a single access point to computational or data resources. P-GRADE is a Grid portal solution that allows users to manage the whole life-cycle for executing a parallel application in the Grid. The purpose of this article is to introduce the structure of a Grid-aware portlet for linear algebra calculations based on the P-GRADE portal. To accomplish this goal, the portlet provides the seamless bridge between the linear algebra calculations and various linear algebra software environments (middlewares, tools, parallel programming techniques, linear algebra libraries) deployed over a grid. The portlet GUI (Graphical User Interface) is lightweight and uses standard web technologies. Moreover, since today smartphone are ubiquitous, we propose to provide an easy and adapted way to monitor the portlets operation from a mobile device and illustrate its practical use.

Enabling Large-Scale Linear Systems of Equations on Hybrid HPC Infrastructures

Scientific research is becoming increasingly dependent on the large-scale analysis of data using High Performance Computing (HPC) infrastructures. Scientific computing aims at constructing mathematical models and numerical solution techniques for solving problems arising in science and engineering. The solution of linear system of equations lies at the heart of most calculations in scientific computing. HPC infrastructures with many-core and graphics processing unit (GPU) challenges, Cloud and Grid technologies and e-infrastructures are currently offering interesting opportunities for solving large-scale linear system of equations. In this article, a second-generation of our Web portal for Scientific Computing is introduced based on a hybrid HPC infrastructure that provides predictable optimal execution and scales from a single resource to multiple resources. After analyzing the synergies and the complementarities of the different computing platforms, we argue for an architecture that combines the benefits of these technologies.

Dynamic Features of Complex Systems: A Molecular Simulation Study

The main aim of the article is the molecular simulation study and detailed analysis of surfactant molecules of complex micellar systems [1-2] consist of long hydrocarbon chain surfactant. The GROMACS software package [3] designed for high-performance simulations of large complex systems is used for the simulations. The IBM BlueGene/P supercomputer [4] at Bulgarian National Centre for Supercomputing Applications, with 8,192 processor cores connected by multiple high-performance networks, enables to investigate a completely new class of problems. The initially random distributed surfactant molecules in aqueous solute hydration have been simulated using GROMOS united atom force field [5]. An extensive series of short benchmarks run for timing purposes with different number of cores show that the studied system achieves good scalability (0.5ns per day) in case of using up to 512 processor cores. Further increasing the numbers of cores (for instance, 1024 cores) does not lead any significant increase. In spite of the limitation of number of simulations, the qualitative statistical data gave some interesting results, which indicates that long hydrocarbon chain surfactant self-assemble into small oligomers since 50ns of simulations, meanwhile in our previous study with surfactant rich content shows that 43ns is enough for self-assembling of spherical micelle.

Cloud Service for Numerical Calculations and Visualizations of Photonic Dissipative Systems

Abstract Nowadays quantum physics is crucial for several scientific applications, where it is no longer possible to neglect the environmental interaction, like dissipation and decoherence. In these cases, the quantum systems are usually treated as open systems and their time-evolution is described by a density matrix in frames of the master equation, instead of the Hilbert-space vector and the Schrodinger equation. The visualization of such quantum systems allows users to calculate and study the sensitivity of the parameters, like excitation photon numbers or photonnumber distribution functions or Wigner functions. In this paper, a cloud service for numerical calculations and visualization of photonic dissipative systems is presented, which enables numerical simulations and visualizations of a wide variety of Hamiltonians, including those with arbitrary time-dependences widely used in many physics applications. The service allows creating graphics and charts for interacting complex systems and simulating their time evolution with many available timeevolution drivers.