To efficiently use alternate paths during periods of congestion, we have devised prioritized Dynamic Routing
Control Agent (pDRCA) that (1) selects best links to meet the bandwidth and delay requirements of traffic, (2)
provides load-balancing and traffic prioritization when multiple topologies are available, and (3) handles changes
in link quality and traffic demand, and link outages. pDRCA provides multiplatform load balancing to maximize
SATCOM (both P2P and multi-point) and airborne links utilization. It influences link selection by configuring the
cost metrics on a router's interface, which does not require any changes to the routing protocol itself. It supports
service differentiation of multiple traffic priorities by providing more network resources to the highest priority
flows. pDRCA does so by solving an optimization problem to find optimal links weights that increase throughput
and decrease E2E delay; avoid congested, low quality, and long delay links; and exploit path diversity in the network. These optimal link weights are sent to the local agents to be configured on individual routers per traffic priority. The pDRCA optimization algorithm has been proven effective in improving application performance. We created a variety of different test scenarios by varying traffic profile and link behavior (stable links, varying capacity, and link outages). In the scenarios where high priority traffic experienced significant loss without pDRCA, the average loss was reduced from 49.5% to 13% and in some cases dropped to 0%. Currently, pDRCA is integrated with an open-source software router and priority queues on Linux as a component of Open Tactical Router (OTR), which is being developed by ONR DTCN program.
KEYWORDS: Human-machine interfaces, Commercial off the shelf technology, Sensor networks, Receivers, Network architectures, Sensors, Switches, Local area networks, Satellites, Systems modeling
WISER is a scalable network emulation tool for networks with several hundred heterogeneous wireless nodes. It
provides high-fidelity network modeling, exchanges packets in real-time, and faithfully captures the complex
interactions among network entities. WISER runs on inexpensive COTS platforms and represents multiple full network
stacks, one for each individual virtual node. It supports a flexible open source router platform (XORP) to implement
routing protocol stacks. WISER offers wireless MAC emulation capabilities for different types of links, waveforms,
radio devices, etc. We present experiments to demonstrate WISER's capabilities enabling a new paradigm for
performance evaluation of mobile sensor and ad-hoc networks.
This document presents the conception of electronic controller for Power Supply subsystem for MXGS (Miniature X-ray
and Gamma Sensor) payload of ASIM (Atmospheric Space Interaction Monitor) experiment to be located onboard
International Space Station as an add-on for European Space Laboratory - Columbus. The aim of this experiment is to
investigate interactions between upper layers of Earth's atmosphere and the outer space. One of the methods of
conducting this kind of examination is planned to be performed by means of MXGS subsystem using a set of CdZnTe
detectors. These are utilized to acquire data about Gamma and X radiation, emitted during specific natural electric
discharges for spectral analysis purposes. Power supply of detector crystals and corresponding front-end electronics
represents very important matter for whole payload subsystem, therefore major focus was put on proper monitoring of
Power Supply Unit's performance. Power Supply Controller must operate in harsh space environment therefore
utilization of space qualified components is taken under consideration.
KEYWORDS: Field programmable gate arrays, Satellites, Error control coding, Temperature metrology, Computer programming, Reliability, Manufacturing, Data acquisition, Clocks, Commercial off the shelf technology
This paper holds an information about an extension module for Single Board Computer (MIP405), which is the heart of
On-board Data Handling Module (OBDH) of student Earth's microsatellite - SSETI ESEO. OBDH is a PC104 stack of
four boards electrically connected and mechanically fixed. On-Board Computer is a key subsystem to the mission
success - it is responsible for distribution of control signals to each module of the spacecraft. It is also expected to
gather critical data for an appropriate mission progress, implementation of a part of algorithms used for satellite
stabilization and orbit control and, at last, processing telecommands. Since whole system should meet spaceborne
application requirements, it must be exceptionally reliable.
Blind source separation (BSS) and related methods such as
independent component analysis (ICA) and their extensions or
sparse component analysis (SCA) refers to wide class of problems
in signal and image processing, when one needs to extract the
underlying sources from a set of mixture. The goal of BSS can be
considered as estimation of true physical sources and parameters
of a mixing system, while objective of generalized component
analysis (GCA) is finding a new reduced or hierarchical and
structured representation for the observed (sensor)
multidimensional data that can be interpreted as physically
meaningful coding or blind signal decompositions. These methods
are generally based on a wide class of unsupervised learning
algorithms and they found potential applications in many areas
from engineering to neuroscience. The recent trends in blind
source separation and generalized component analysis is to
consider problems in the framework of matrix factorization or more
general signals decomposition with probabilistic generative and
tree structured graphical models and exploit some priori
knowledge about true nature and structure of latent (hidden)
components or sources such as spatio-temporal decorrelation,
statistical independence, sparsity, nonnegativity, smoothness or
lowest possible complexity. The key issue is to find a such
transformation or coding which has true physical meaning and
interpretation. In this paper we discuss some promising approaches
and algorithms for BSS/GCA, especially for ICA and SCA in order to
analyze, enhance, perform feature extraction, removing artifacts
and denoising of multi-modal, multi-sensory data.
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