Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Fast parallel algorithms for short-range molecular dynamics

Statistics for Spatial Data.

The Internet has led to the creation of a digital society, where (almost) everything is connected and is accessible from anywhere. However, despite their widespread adoption, traditional IP networks are complex and very hard to manage. It is both difficult to configure the network according to predefined policies, and to reconfigure it to respond to faults, load, and changes. To make matters even more difficult, current networks are also vertically integrated: the control and data planes are bundled together. Software-defined networking (SDN) is an emerging paradigm that promises to change this state of affairs, by breaking vertical integration, separating the network's control logic from the underlying routers and switches, promoting (logical) centralization of network control, and introducing the ability to program the network. The separation of concerns, introduced between the definition of network policies, their implementation in switching hardware, and the forwarding of traffic, is key to the desired flexibility: by breaking the network control problem into tractable pieces, SDN makes it easier to create and introduce new abstractions in networking, simplifying network management and facilitating network evolution. In this paper, we present a comprehensive survey on SDN. We start by introducing the motivation for SDN, explain its main concepts and how it differs from traditional networking, its roots, and the standardization activities regarding this novel paradigm. Next, we present the key building blocks of an SDN infrastructure using a bottom-up, layered approach. We provide an in-depth analysis of the hardware infrastructure, southbound and northbound application programming interfaces (APIs), network virtualization layers, network operating systems (SDN controllers), network programming languages, and network applications. We also look at cross-layer problems such as debugging and troubleshooting. In an effort to anticipate the future evolution of this new paradigm, we discuss the main ongoing research efforts and challenges of SDN. In particular, we address the design of switches and control platforms—with a focus on aspects such as resiliency, scalability, performance, security, and dependability—as well as new opportunities for carrier transport networks and cloud providers. Last but not least, we analyze the position of SDN as a key enabler of a software-defined environment.

https://publications.uni.lu/bitstream/10993/20596/1/survey_on_SDN.pdf

Software-Defined Networking: A Comprehensive Survey

Software-Defined Networking (SDN) is an emerging paradigm that promises to change this state of affairs, by breaking vertical integration, separating the network's control logic from the underlying routers and switches, promoting (logical) centralization of network control, and introducing the ability to program the network. The separation of concerns introduced between the definition of network policies, their implementation in switching hardware, and the forwarding of traffic, is key to the desired flexibility: by breaking the network control problem into tractable pieces, SDN makes it easier to create and introduce new abstractions in networking, simplifying network management and facilitating network evolution. In this paper we present a comprehensive survey on SDN. We start by introducing the motivation for SDN, explain its main concepts and how it differs from traditional networking, its roots, and the standardization activities regarding this novel paradigm. Next, we present the key building blocks of an SDN infrastructure using a bottom-up, layered approach. We provide an in-depth analysis of the hardware infrastructure, southbound and northbound APIs, network virtualization layers, network operating systems (SDN controllers), network programming languages, and network applications. We also look at cross-layer problems such as debugging and troubleshooting. In an effort to anticipate the future evolution of this new paradigm, we discuss the main ongoing research efforts and challenges of SDN. In particular, we address the design of switches and control platforms -- with a focus on aspects such as resiliency, scalability, performance, security and dependability -- as well as new opportunities for carrier transport networks and cloud providers. Last but not least, we analyze the position of SDN as a key enabler of a software-defined environment.

The Transmission Control Protocol.

Current collaborative filtering can't represent various aspects of users' interests. We propose a recommendation method in which a user can find new interests that are partially similar to the user's taste. Partial similarity is an aspect of the user's preference which is projected by the community in which the user belongs. We developed a television program recommendation system which performs such recommendation with serendipity, conducted an actual experiment and evaluated its results.

A Community-Based Recommendation System to Reveal Unexpected Interests

A high speed computer network will provide us with new broadband multimedia applications. This paper discusses new functions for the next generation VRML (Virtual Reality Modeling Language) over high speed computer networks. The LoD (Level of Detail) of 3D objects is the most important function for rendering scenes dynamically while managing the QoS (Quality of Service). New requirements for the next generation VRML are discussed. We present Differential VRML (DVRML) in order to update scene graphs dynamically, and describe principles of the LoD function based on the DVRML.

Dynamic LoD for QoS management in the next generation VRML

With the popularization of todays mobile devices, the environment that enables us to publish and utilize information independent of location and time has been actualized. In the future, various kinds of sensors such as GPS as well as network-enabled appliances will also be connected to the Internet. By utilizing various kinds of information acquired from these network terminals, advanced context-aware services will be produced. For realizing context-aware services, we focus on information management and retrieval using a Peer-to-Peer (P2P) network. In this paper, we propose a location-based P2P network named the LL-Net. By constructing a P2P overlay network based on locations of peers, the LL-Net achieves efficient propagation of location-dependent queries issued by context-aware services.

A Location-Based Peer-to-Peer Network for Context-Aware Services in a Ubiquitous Environment

Recently we have seen an increase in the calls for universities and the education community to re-think undergraduate education and create opportunities that prepare students as effective global professionals. The key motivator is the need to build a research and industrial workforce that works collaboratively across cultures and disciplines to address major global challenges. At the same time, computing, information, and communication technology facilitates a comprehensive 'cyberinfrastructure' on which new types of scientifc and engineering knowledge environments and organizations can be constructed. We describe our four-year pilot experience with the Pacifc Rim experiences for undergraduates (PRIME) project. The goals of PRIME are to: develop an integrated and sustainable undergraduate international research program that serves as a model for 21st century undergraduate education; prepare students to become effective global professionals and citizens; and, give students a head-start on careers in science, engineering and technology research. We discuss the design and motivation for the scheme, salient implementation details, outcomes to date and discuss challenges of scalability and sustainability.

/pdf/prime-an-integrated-and-sustainable-undergraduate-3bsf6mqawb.pdf

Prime: An integrated and sustainable undergraduate international research program

This paper proposes a multimedia presentation system Harmony which can deal with temporal and active media such as motion video, computer animation, and music sounds. Harmony is based on the notion of a hyperobject which integrates a hypertext system with an object-oriented framework. Each object is considered a node as is usual in hypertext systems, and the relations between objects are represented as links between nodes. Harmony extends the ordinary notion of a link. A link in Harmony consists of three components: objects connected by the link, conditions specifying when the link is navigated, andmessages sent to the target object. In addition to such an extension, each object can include internal objects called subobjects which specify parts of an object and can become a source/destination of a link. Furthermore, the notion of a group object is introduced to represent a synchronization of parallel displayed media information. Through these extended notions of a hypertext model, temporal and active media can be easily handled through the description of temporal relations from the media in hypermedia documents. Based on the design of Harmony, we have implemented a prototype multimedia presentation system which deals with text, music, graphics, motion video, and computer animation as objects. Harmony consists of three subsystems: link manager subsystem (Harmony/LM), user interface subsystem (Harmony/UI), and object-oriented database (Harmony/DB), where a commercial objectoriented database was employed as the Harmony/DB. Scenario viewer was developed for displaying the structure of scenario in a tree graph which can reduce a cognitive overhead in a hypermedia document. The whole system was constructed based on C++ language.

Shinji Shimojo

Papers

A Community-Based Recommendation System to Reveal Unexpected Interests

Dynamic LoD for QoS management in the next generation VRML

A Location-Based Peer-to-Peer Network for Context-Aware Services in a Ubiquitous Environment

Prime: An integrated and sustainable undergraduate international research program

Multimedia Presentation System Harmony with Temporal and Active Media.