Jmas: A Java-based Mobile Actor System for Heterogeneous Distributed Parallel Computing

Computer Scienc

Efficient Coding of the Prediction Residual

Electrical Engineerin

Decentralized Algorithm for Communication Efficient Distributed Shared Memory

A sequential computer executes one CPU instruction at a time. Over the years sequential computers have increased steadily in performance primarily as a result of improvements in digital hardware technology. One major concern of computer designers is that logic and memory devices are approaching ultimate physical limits on their size and speed. While size reductions and speed increases of a few orders of magnitude beyond present levels seem feasible, further improvements in the performance of sequential computers may not be achievable at acceptable cost. A more economic solution is to design systems that can process more than one CPU instruction at a time. This is known as parallel processing. Parallel processors are also referred to as distributed systems. These systems consists of an interconnected collection of autonomous computers [Sta84]. There are many ways of classifying distributed systems based on their structure or behavior. Based on Flynn's taxonomy of computer architectures, distributed systems belong to the MIMD (multiple instruction multiple data) class of computer architectures [Tan92]. The MIMD class consist of two categories: those that have shared memory (tightly coupled), and those that do not (loosely coupled). As shown in Figure 1.1, each category can be furthered divided based on the architecture of the interconnection network. In bus-based systems, there is a single network, backplane, bus, cable, or other medium that connects all machines. Switched systems connect machines by individual wires

Intensity-Based Skeletonization of CryoEM Gray-Scale Images Using a True Segmentation-Free Algorithm

Cryo-electron microscopy is an experimental technique that is able to produce 3D gray-scale images of protein molecules. In contrast to other experimental techniques, cryo-electron microscopy is capable of visualizing large molecular complexes such as viruses and ribosomes. At medium resolution, the positions of the atoms are not visible and the process cannot proceed. The medium-resolution images produced by cryo-electron microscopy are used to derive the atomic structure of the proteins in de novo modeling. The skeletons of the 3D gray-scale images are used to interpret important information that is helpful in de novo modeling. Unfortunately, not all features of the image can be captured using a single segmentation. In this paper, we present a segmentation-free approach to extract the gray-scale curve-like skeletons. The approach relies on a novel representation of the 3D image, where the image is modeled as a graph and a set of volume trees. A test containing 36 synthesized maps and one authentic map shows that our approach can improve the performance of the two tested tools used in de novo modeling. The improvements were 62 and 13 percent for Gorgon and DP-TOSS, respectively

JMAS: A Java-Based Mobile Actor System for Distributed Parallel Computation

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Efficient Scheduling of Pigeons for a Constrained Delay Tolerant Application

Information collection in the disaster area is an important application of pigeon networks&#8212;a special type of delay tolerant networks (DTNs) that borrows the ancient idea of using pigeons as the telecommunication method. The aim of this paper is to explore highly efficient scheduling strategies of pigeons for such applications. The upper bound of traffic that can be supported under the deadline constraints for the basic on-demand strategy is given through the analysis. Based on the analysis, a waiting-based packing strategy is introduced. Although the latter strategy could not change the maximum traffic rate that a pigeon can support, it improves the efficiency of a pigeon largely. The analytical results are verified by the simulations.</p