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  • 1.
    Ashraf, Adnan
    et al.
    Abo Akad Univ, Fac Sci & Engn, Turku, Finland..
    Majd, Amin
    Abo Akad Univ, Fac Sci & Engn, Turku, Finland..
    Troubitsyna, Elena
    KTH, School of Electrical Engineering and Computer Science (EECS), Computer Science, Theoretical Computer Science, TCS.
    Online Path Generation and Navigation for Swarms of UAVs2020In: Scientific Programming, ISSN 1058-9244, E-ISSN 1875-919X, Vol. 2020, article id 8530763Article in journal (Refereed)
    Abstract [en]

    With the growing popularity of unmanned aerial vehicles (UAVs) for consumer applications, the number of accidents involving UAVs is also increasing rapidly. Therefore, motion safety of UAVs has become a prime concern for UAV operators. For a swarm of UAVs, a safe operation cannot be guaranteed without preventing the UAVs from colliding with one another and with static and dynamically appearing, moving obstacles in the flying zone. In this paper, we present an online, collision-free path generation and navigation system for swarms of UAVs. The proposed system uses geographical locations of the UAVs and of the successfully detected, static, and moving obstacles to predict and avoid the following: (1) UAV-to-UAV collisions, (2) UAV-to-static-obstacle collisions, and (3) UAV-to-moving-obstacle collisions. Our collision prediction approach leverages efficient runtime monitoring and complex event processing (CEP) to make timely predictions. A distinctive feature of the proposed system is its ability to foresee potential collisions and proactively find best ways to avoid predicted collisions in order to ensure safety of the entire swarm. We also present a simulation-based implementation of the proposed system along with an experimental evaluation involving a series of experiments and compare our results with the results of four existing approaches. The results show that the proposed system successfully predicts and avoids all three kinds of collisions in an online manner. Moreover, it generates safe and efficient UAV routes, efficiently scales to large-sized problem instances, and is suitable for cluttered flying zones and for scenarios involving high risks of UAV collisions.

  • 2.
    Brandic, Ivona
    et al.
    University of Vienna, Austria.
    Pllana, Sabri
    University of Vienna, Austria.
    Benkner, Siegfried
    University of Vienna, Austria.
    An approach for the high-level specification of QoS-aware grid workflows considering location affinity2006In: Scientific Programming, ISSN 1058-9244, E-ISSN 1875-919X, Vol. 14, no 3-4, p. 231-250Article in journal (Refereed)
    Abstract [en]

    Many important scientific and engineering problems may be solved by combining multiple applications in the form of a Grid workflow. We consider that for the wide acceptance of Grid technology it is important that the user has the possibility to express requirements on Quality of Service (QoS) at workflow specification time. However, most of the existing workflow languages lack constructs for QoS specification. In this paper we present an approach for high level workflow specification that considers a comprehensive set of QoS requirements. Besides performance related QoS, it includes economical, legal and security aspects. For instance, for security or legal reasons the user may express the location affinity regarding Grid resources on which certain workflow tasks may be executed. Our QoS-aware workflow system provides support for the whole workflow life cycle from specification to execution. Workflow is specified graphically, in an intuitive manner, based on a standard visual modeling language. A set of QoS-aware service-oriented components is provided for workflow planning to support automatic constraint-based service negotiation and workflow optimization. For reducing the complexity of workflow planning, we introduce a QoS-aware workflow reduction technique. We illustrate our approach with a real-world workflow for maxillo facial surgery simulation.

  • 3. George, William
    et al.
    Brickner, Ralph G
    Johnsson, Lennart
    KTH, School of Computer Science and Communication (CSC), Centres, Centre for High Performance Computing, PDC.
    POLYSHIFT Communications Software for the Connection Machine System CM–2001994In: Scientific Programming, ISSN 1058-9244, E-ISSN 1875-919X, Vol. 3, no 1, p. 83-99Article in journal (Refereed)
    Abstract [en]

    We describe the use and implementation of a polyshift function PSHIFT for circular shifts and end-offs shifts. Polyshift is useful in many scientific codes using regular grids, such as finite difference codes in several dimensions, and multigrid codes, molecular dynamics computations, and in lattice gauge physics computations, such as quantum chromodynamics (QCD) calculations. Our implementation of the PSHIFT function on the Connection Machine systems CM-2 and CM-200 offers a speedup of up to a factor of 3-4 compared with CSHIFT when the local data motion within a node is small. The PSHIFT routine is included in the Connection Machine Scientific Software Library (CMSSL).

  • 4. Hu, Yu
    et al.
    Johnsson, Lennart
    KTH, School of Computer Science and Communication (CSC), Centres, Centre for High Performance Computing, PDC.
    Implementing O(N ) N–body algorithms efficiently in data parallel languages1996In: Scientific Programming, ISSN 1058-9244, E-ISSN 1875-919X, Vol. 5, no 4, p. 337-364Article in journal (Refereed)
    Abstract [en]

    The optimization techniques for hierarchical O(N) N-body algorithms described here focus on managing the data distribution and the data references, both between the memories of different nodes and within the memory hierarchy of each node. We show how the techniques can be expressed in data-parallel languages, such as High Performance Fortran (HPF) and Connection Machine Fortran (CMF). The effectiveness of our techniques is demonstrated on an implementation of Anderson's hierarchical O(N) N-body method for the Connection Machine system CM-5/5E. Of the total execution time, communication accounts for about 10-20% of the total time, with the average efficiency for arithmetic operations being about 40% and the total efficiency (including communication) being about 35%. For the CM-5E, a performance in excess of 60 Mflop/s per node (peak 160 Mflop/s per node) has been measured.

  • 5. Marthur, Kapil K
    et al.
    Johnsson, Lennart
    KTH, School of Computer Science and Communication (CSC), Centres, Centre for High Performance Computing, PDC.
    All–to–All Communication on the Connection Machine system CM–2001995In: Scientific Programming, ISSN 1058-9244, E-ISSN 1875-919X, Vol. 4, no 4, p. 251-273Article in journal (Refereed)
    Abstract [en]

    based on all--to--all broadcast and all--to--all reduce are presented. For DBLAS, at each all--to--all step, it is necessary to know the data values and the indices of the data values as well. This is in contrast to the more traditional applications of all--to--all broadcast (such as a N--body solver) where the identity of the data values is not of much interest. Detailed schedules for all--to--all broadcast and reduction are given for the data motion of arrays mapped to the processing nodes of binary cube networks using binary encoding and binary--reflected Gray encoding. The algorithms compute the indices for the communicated data locally. No communication bandwidth is consumed for data array indices. For the Connection Machine system CM--200, Hamiltonian cycle based all--to--all communication algorithms improve the performance by a factor of two to ten over a combination of tree, butterfly network, and router based algorithms. The data rate achieved for all--to--all broadcast on a 256 node Connection Machine system CM--200 is 0.3 Gbytes/sec. The data motion rate for all--to--all broadcast, including the time for index computations and local data reordering, is about 2.8 Gbytes/sec for a 2048 node system. Excluding the time for index computation and local memory reordering the measured data motion rate for all--to--all broadcast is 5.6 Gbytes/s. On a Connection Machine system, CM--200, with 2048 processing nodes, the overall performance of the distributed matrix vector multiply (DGEMV) and vector matrix multiply (DGEMV with TRANS) is 10.5 Gflops/s and 13.7 Gflops/s respectively

  • 6.
    Mossberg, Eva
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Scientific Computing. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Numerical Analysis.
    Otto, Kurt
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Scientific Computing. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Numerical Analysis.
    Thuné, Michael
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Scientific Computing. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Numerical Analysis.
    Object-oriented software tools for the construction of preconditioners1997In: Scientific Programming, ISSN 1058-9244, E-ISSN 1875-919X, Vol. 6, p. 285-295Article in journal (Refereed)
  • 7.
    Muddukrishna, A.
    et al.
    KTH Royal Institute of Technology, Sweden.
    Jonsson, Peter
    RISE, Swedish ICT, SICS.
    Brorsson, Mats
    RISE, Swedish ICT, SICS. KTH Royal Institute of Technology, Sweden.
    Locality-aware task scheduling and data distribution for OpenMP programs on NUMA systems and manycore processors2015In: Scientific Programming, ISSN 1058-9244, E-ISSN 1875-919X, Vol. 2015, article id 981759Article in journal (Refereed)
    Abstract [en]

    Performance degradation due to nonuniform data access latencies has worsened on NUMA systems and can now be felt on-chip in manycore processors. Distributing data across NUMA nodes and manycore processor caches is necessary to reduce the impact of nonuniform latencies. However, techniques for distributing data are error-prone and fragile and require low-level architectural knowledge. Existing task scheduling policies favor quick load-balancing at the expense of locality and ignore NUMA node/manycore cache access latencies while scheduling. Locality-aware scheduling, in conjunction with or as a replacement for existing scheduling, is necessary to minimize NUMA effects and sustain performance. We present a data distribution and locality-aware scheduling technique for task-based OpenMP programs executing on NUMA systems and manycore processors. Our technique relieves the programmer from thinking of NUMA system/manycore processor architecture details by delegating data distribution to the runtime system and uses task data dependence information to guide the scheduling of OpenMP tasks to reduce data stall times. We demonstrate our technique on a four-socket AMD Opteron machine with eight NUMA nodes and on the TILEPro64 processor and identify that data distribution and locality-aware task scheduling improve performance up to 69% for scientific benchmarks compared to default policies and yet provide an architecture-oblivious approach for programmers

  • 8.
    Muddukrishna, Ananya
    et al.
    KTH, School of Information and Communication Technology (ICT), Electronic Systems.
    Jonsson, Peter A.
    SICS Swedish ICT AB.
    Brorsson, Mats
    KTH, School of Information and Communication Technology (ICT), Software and Computer systems, SCS. SICS Swedish ICT AB.
    Locality-aware Task Scheduling and Data Distribution for OpenMP Programs on NUMA Systems and Manycore Processors2015In: Scientific Programming, ISSN 1058-9244, E-ISSN 1875-919X, article id 981759Article in journal (Refereed)
    Abstract [en]

    Performance degradation due to nonuniform data access latencies has worsened on NUMA systems and can now be felt on-chip in manycore processors. Distributing data across NUMA nodes and on manycore processors is necessary to reduce the impact of nonuniform latencies. However, techniques for distributing data are error-prone and fragile and require low-level architectural knowledge. Existing task scheduling policies favor quick load-balancing at the expense of locality and ignore NUMA node access latencies while scheduling. Locality-aware scheduling, in conjunction with or as a replacement for existing scheduling, is necessary to minimize NUMA effects and sustain performance. We present a data distribution and locality-aware scheduling technique for task-based OpenMP programs executing on NUMA systems and manycore processors. Our technique relieves the programmer from thinking of NUMA architecture details by delegating data distribution to the runtime system and uses task data dependence information to guide the scheduling of OpenMP tasks to reduce data stall times. We demonstrate our technique on a four-socket AMD Opteron machine with eight NUMA nodes and on the TILEPro64 processor, and we identify that data distribution and locality-aware task scheduling improve performance up to 69% for scientific benchmarks compared to default policies and yet provide an architecture-oblivious approach for programmers.

  • 9.
    Nieves, Juan Carlos
    et al.
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Osorio, Mauricio
    Extending Well-Founded Semantics with Clark's Completion for Disjunctive Logic Programs2018In: Scientific Programming, ISSN 1058-9244, E-ISSN 1875-919X, article id 4157030Article in journal (Refereed)
    Abstract [en]

    In this paper, we introduce new semantics (that we call D3-WFS-DCOMP) and compare it with the stable semantics (STABLE). For normal programs, this semantics is based on suitable integration of the well-founded semantics (WFS) and the Clark's completion. D3-WFS-DCOMhas the following appealing properties: First, it agrees with STABLE in the sense that it never defines a nonminimal model or a nonminimal supported model. Second, for normal programs it extends WFS. Third, every stable model of a disjunctive program.. is a D3-WFS-DCOM model of P. Fourth, it is constructed using transformation rules accepted by STABLE. We also introduce second semantics that we call D2-WFS-DCOMP. We show that D2-WFS-DCOMP is equivalent to D3-WFS-DCOMP for normal programs but this is not the case for disjunctive programs. We also introduce third new semantics that supports the use of implicit disjunctions. We illustrate how these semantics can be extended to programs including explicit negation, default negation in the head of a clause, and a lub operator, which is a generalization of the aggregation operator setof over arbitrary complete lattices.

  • 10.
    Pllana, Sabri
    et al.
    University of Vienna.
    Träff, Jesper
    University of Vienna.
    Introduction to the Scientific ProgrammingSpecial Issue: Software Development forMulti-core Computing Systems2009In: Scientific Programming, ISSN 1058-9244, E-ISSN 1875-919X, Vol. 17, no 4, p. 283-284Article in journal (Other academic)
  • 11. Proaño Orellana, Julio
    et al.
    Caminero, Bianca
    Carrión, Carmen
    Tomas, Luis
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Kostentinos Tesfatsion, Selome
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Tordsson, Johan
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    FPGA-Aware Scheduling Strategies at Hypervisor Level in Cloud Environments2016In: Scientific Programming, ISSN 1058-9244, E-ISSN 1875-919X, article id 4670271Article in journal (Refereed)
    Abstract [en]

    Current open issues regarding cloud computing include the support for nontrivial Quality of Service-related Service Level Objectives (SLOs) and reducing the energy footprint of data centers. One strategy that can contribute to both is the integration of accelerators as specialized resources within the cloud system. In particular, Field Programmable Gate Arrays (FPGAs) exhibit an excellent performance/energy consumption ratio that can be harnessed to achieve these goals. In this paper, a multilevel cloud scheduling framework is described, and several FPGA-aware node level scheduling strategies (applied at the hypervisor level) are explored and analyzed. These strategies are based on the use of a multiobjective metric aimed at providing Quality of Service (QoS) support. Results show how the proposed FPGA-aware scheduling policies increment the number of users requests serviced with their SLOs fulfilled while energy consumption is minimized. In particular, evaluation results of a use case based on a multimedia application show that the proposal can save more than 20% of the total energy compared with other baseline algorithms while a higher percentage of Service Level Agreement (SLA) is fulfilled.

  • 12.
    Sheshadri, Krishnamurthy
    et al.
    Connexios Life Sciences, Bangalore, India.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    A general symbolic PDE solver generator: Beyond explicit schemes2003In: Scientific Programming, ISSN 1058-9244, E-ISSN 1875-919X, Vol. 11, no 3, p. 225-235Article in journal (Refereed)
    Abstract [en]

    This paper presents an extension of our Mathematica- and MathCode-based symbolic-numeric framework for solving a variety of partial differential equation (PDE) problems. The main features of our earlier work, which implemented explicit finite-difference schemes, include the ability to handle (1) arbitrary number of dependent variables, (2) arbitrary dimensionality, and (3) arbitrary geometry, as well as (4) developing finite-difference schemes to any desired order of approximation. In the present paper, extensions of this framework to implicit schemes and the method of lines are discussed. While C++ code is generated, using the MathCode system for the implicit method, Modelica code is generated for the method of lines. The latter provides a preliminary PDE support for the Modelica language. Examples illustrating the various aspects of the solver generator are presented.

  • 13.
    Sheshadri, Krishnamurthy
    et al.
    Connexios Life Sciences, Bangalore, India.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory. Linköping University, The Institute of Technology.
    A General Symbolic PDE-Solver Generator: Explicit Schemes2003In: Scientific Programming, ISSN 1058-9244, E-ISSN 1875-919X, Vol. 11, no 1, p. 39-55Article in journal (Refereed)
    Abstract [en]

    A symbolic solver generator to deal with a system of partial differential equations (PDEs) in functions of an arbitrary number of variables is presented; it can also handle arbitrary domains (geometries) of the independent variables. Given a system of PDEs, the solver generates a set of explicit finite-difference methods to any specified order, and a Fourier stability criterion for each method. For a method that is stable, an iteration function is generated symbolically using the PDE and its initial and boundary conditions. This iteration function is dynamically generated for every PDE problem, and its evaluation provides a solution to the PDE problem. A C++/Fortran 90 code for the iteration function is generated using the MathCode system, which results in a performance gain of the order of a thousand over Mathematica, the language that has been used to code the solver generator. Examples of stability criteria are presented that agree with known criteria; examples that demonstrate the generality of the solver and the speed enhancement of the generated C++ and Fortran 90 codes are also presented.

  • 14.
    Viklund, Lars
    et al.
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Fritzson, Peter
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    ObjectMath – An Object-Oriented Language and Environment for Symbolic and Numerical Processing in Scientific Computing1995In: Scientific Programming, ISSN 1058-9244, E-ISSN 1875-919X, Vol. 4, no 4, p. 229-250Article in journal (Refereed)
    Abstract [en]

    ObjectMath is a language for scientific computing that integrates object-oriented constructs with features for symbolic and numerical computation. Using ObjectMath, complex mathematical models may be implemented in a natural way. The ObjectMath programming environment provides tools for generating efficient numerical code from such models. Symbolic computation is used to rewrite and simplify equations before code is generated. One novelty of the ObjectMath approach is that it provides a comman language and an integrated environment for this kind of mixed symbolic/numerical computation. The motivation for this work is the current low-level state of the art in programming for scientific computing. Much numerical software is still being developed the traditional way in Fortran. This is especially true in application areas such as machine elements analysis, where complex nonlinear problems are the norm. We believe that tools like ObjectMath can increase productivity and quality, thus enabling users to solve problems that are too complex to handle with traditional tools. 

  • 15. Yamba Yamba, André
    et al.
    Åhlander, Krister
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Numerical Analysis.
    Ljungberg, Malin
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Numerical Analysis.
    Designing for geometrical symmetry exploitation2006In: Scientific Programming, ISSN 1058-9244, E-ISSN 1875-919X, Vol. 14, p. 61-80Article in journal (Refereed)
  • 16.
    Zhu, Yuxiang
    et al.
    Shandong University of Science and Technology, China.
    Peng, Yanjun
    Shandong University of Science and Technology, China.
    Asl, Arsineh Boodaghian
    Karlstad University, Faculty of Arts and Social Sciences (starting 2013), Karlstad Business School (from 2013).
    Dual Adaptive Adjustment for Customized Garment Pattern2019In: Scientific Programming, ISSN 1058-9244, E-ISSN 1875-919X, p. 1-12, article id 8069373Article in journal (Refereed)
    Abstract [en]

    We present a dual adaptive garment slice adjustment technique for automatic resizing of apparel products with variant body shapes, and this technique can quickly generate clothed characters. Our first contribution is to propose a novel fit evaluation method. When a 2D garment pattern and a 3D draped garment have the same triangle topology connection, we calculate the shape variable of each triangle and output heat map simultaneously. For sewing a pattern to a newly targeted human body, we propose a fully automatic adjustment method that conforms to the body structure and is composed of two stages. In the coarse auto adjustment (CAA) stage, we propose a method of controlling the size of a garment by the length of a bounding box in five parts of the human body. Then, the garment pattern is automatically adjusted using the measured dimension, by stretching or shrinking. In the fine auto adjustment (FAA) stage, boundary vertices control the shape in the adjustment process. For better matching with the body, the vertices of the garment pattern boundary are relocated with the calculated moving distance and moving direction. As demonstrated in the results, our method enables fully automatic adjustment, preserving the original pattern style of garments between characters with vastly body shapes. Compared with the state-of-art 2D editing method, our proposed approach leads to time saving, and it achieves realistic garment effect compared to auto fitting methods.

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