7,407 research outputs found
Pipes and Connections
This document describes the low-level Pipe and ConnectionManager objects of the Mesh-
Router system. The overall MeshRouter framework provides a general scheme for interest-
limited communications among a number of client processes. This generality is achieved by
a carefully factorized, object-oriented software implementation. Within this framework, the
Pipe and ConnectionManager (base) classes dened in this note specify the interfaces for i) ac-
tual `bits on the wire' communications and ii) dynamic client insertions during overall system
execution. Two specic implementations of the Pipe class are described in detail: a `Memo-
ryPipe' linking objects instanced on a single processor and a more general 'rtisPipe' providing
inter-processor communications built entirely from the standard RTI-s library used in current
JSAF applications. Initialization procedures within the overall MeshRouter system are dis-
cussed, with particular attention given to dynamic management of inter-processor connections.
Prototype RTI-s router processes are discussed, and simple extensions of the standard system
conguration data les are presented
21st Century Simulation: Exploiting High Performance Computing and Data Analysis
This paper identifies, defines, and analyzes the limitations imposed on Modeling and Simulation by outmoded
paradigms in computer utilization and data analysis. The authors then discuss two emerging capabilities to
overcome these limitations: High Performance Parallel Computing and Advanced Data Analysis. First, parallel
computing, in supercomputers and Linux clusters, has proven effective by providing users an advantage in
computing power. This has been characterized as a ten-year lead over the use of single-processor computers.
Second, advanced data analysis techniques are both necessitated and enabled by this leap in computing power.
JFCOM's JESPP project is one of the few simulation initiatives to effectively embrace these concepts. The
challenges facing the defense analyst today have grown to include the need to consider operations among non-combatant
populations, to focus on impacts to civilian infrastructure, to differentiate combatants from non-combatants,
and to understand non-linear, asymmetric warfare. These requirements stretch both current
computational techniques and data analysis methodologies. In this paper, documented examples and potential
solutions will be advanced. The authors discuss the paths to successful implementation based on their experience.
Reviewed technologies include parallel computing, cluster computing, grid computing, data logging, OpsResearch,
database advances, data mining, evolutionary computing, genetic algorithms, and Monte Carlo sensitivity analyses.
The modeling and simulation community has significant potential to provide more opportunities for training and
analysis. Simulations must include increasingly sophisticated environments, better emulations of foes, and more
realistic civilian populations. Overcoming the implementation challenges will produce dramatically better insights,
for trainees and analysts. High Performance Parallel Computing and Advanced Data Analysis promise increased
understanding of future vulnerabilities to help avoid unneeded mission failures and unacceptable personnel losses.
The authors set forth road maps for rapid prototyping and adoption of advanced capabilities. They discuss the
beneficial impact of embracing these technologies, as well as risk mitigation required to ensure success
EventKG+BT: Generation of Interactive Biography Timelines from a Knowledge Graph
Research on notable accomplishments and important events in the life of
people of public interest usually requires close reading of long encyclopedic
or biographical sources, which is a tedious and time-consuming task. Whereas
semantic reference sources, such as the EventKG knowledge graph, provide
structured representations of relevant facts, they often include hundreds of
events and temporal relations for particular entities. In this paper, we
present EventKG+BT - a timeline generation system that creates concise and
interactive spatio-temporal representations of biographies from a knowledge
graph using distant supervision.Comment: ESWC 2020 Satellite Events pp 91-9
Computational and theoretical aspects of a grain-boundary model at finite deformations
A model to describe the role of grain boundaries in the overall response of a polycrystalline material at small length scales subject to finite deformations is presented. Three alternative thermodynamically consistent plastic flow relations on the grain boundary are derived and compared using a series of numerical experiments. The numerical model is obtained by approximating the governing relations using the finite element method. In addition, the infinitesimal and finite deformation theories are compared, and the limitations of the former made clear
Concurrent Multi-Target Tracking
Simulation89 is an emulation of various SDI tasks (tracking,
engagement management and âlook aheadâ) developed for the
U. S. Air Force. The simulation presently deals with
the boost, post-boost and early midcourse phases of
a âmass raidâ scenario, and is designed to process scenarios with a few thousand targets. The simulation is run on
the Mark-III hypercube, with individual tasks performed
on subcubes of the full hypercube. In general, the computations within individual subcubes are done in
a synchronous manner (i.e., CrOS), while communications between tasks/subcubes are done asynchronously
Computational and theoretical aspects of a grain-boundary model that accounts for grain misorientation and grain-boundary orientation
A detailed theoretical and numerical investigation of the infinitesimal
single-crystal gradient plasticity and grain-boundary theory of Gurtin (2008)
"A theory of grain boundaries that accounts automatically for grain
misorientation and grain-boundary orientation". Journal of the Mechanics and
Physics of Solids 56 (2), 640-662, is performed. The governing equations and
flow laws are recast in variational form. The associated incremental problem is
formulated in minimization form and provides the basis for the subsequent
finite element formulation. Various choices of the kinematic measure used to
characterize the ability of the grain boundary to impede the flow of
dislocations are compared. An alternative measure is also suggested. A series
of three-dimensional numerical examples serve to elucidate the theory
Earnings distribution, corporate governance and CEO pay
We investigate the relationship between earnings differentials and the pay of CEOs of 190 British companies between 1970 and 1990. We find that (i) changes in the differential between the 90th and 50th weekly earnings percentiles for non-manual adult male workers [90:50] explain changes in the level of real CEO salary and bonus in our sample of companies; (ii) changes in this differential also account for changes in the elasticity of CEO pay to firm size; (iii) a broader measure of earnings inequality does far worse than 90:50 at explaining changes in both the level and the firm size elasticity of CEO pay; (iv) fitting the model on data for 1970-1983 and predicting pay levels for the period starting with the widespread adoption of executive share option schemes in 1984, we find a structural break in the relationship between lower management pay differentials and the pay of the CEO. We conclude first that top executive pay prior to 1984 was a stable function of both firm size and earnings differentials lower on the administrative ladder, consistent with a hypothesis advanced by Herbert Simon in 1957; and second that the use of share options from 1984 onward represents not simply a change in the mode of top executive compensation, but a de -linking of the pay of top executives and that of their subordinates
- âŠ