The Computation and Transmission Rate Based (CTRB) Algorithm for Distributed Applications

MAX-MIN FAIR FLOW CONTROL SENSITIVE TO PRIORITIES

Journal of Interconnection Networks ◽

10.1142/s0219265905001332 ◽

2005 ◽

Vol 06 (02) ◽

pp. 85-114 ◽

Cited By ~ 2

Author(s):

PANAGIOTA FATOUROU ◽

MARIOS MAVRONICOLAS ◽

PAUL SPIRAKIS

Keyword(s):

Flow Control ◽

Communication Networks ◽

Transmission Rate ◽

Distributed Applications ◽

Network Resources ◽

Combinatorial Properties ◽

Individual Session ◽

A Priority ◽

Priority Function ◽

Fairness Condition

Flow control is the dominant technique currently used in communication networks for preventing excess traffic from flooding the network, and for handling congestion. In rate-based flow control, transmission rates of sessions are adjusted in an end-to-end manner through a sequence of operations. In this work, we present a theory of max-min fair, rate-based flow control sensitive to priorities of different sessions, as a significant extension of the classical theory of max-min fair, rate-based flow control to networks supporting applications with diverse requirements on network resources. Each individual session bears a priority function, which maps the session's priority to a transmission rate; the priority is a working abstraction of the session's priority to bandwidth access. Priority functions enable the specification of requirements on bandwidth access by distributed applications, and the formal handling of such requirements. We present priority max-min fairness, as a novel and well motivated fairness condition which requires that assigned rates correspond, through the priority functions, to priorities comprising a max-min vector. We also introduce priority bottleneck algorithms gradually update a session's rate until when its priority is restricted on a priority bottleneck edge of the network. We establish a collection of interesting combinatorial properties of priority bottleneck algorithms. Most significantly, we show that they can only converge to priority max-min fairness. As an application of our general theory, we embed priority bottleneck algorithms in the more realistic optimistic framework for rate-based flow control. The optimistic framework allows for both decreases and increases of session rates. We exploit these additionally provided semantics to prove further combinatorial properties for the termination of priority bottleneck algorithms in the optimistic framework. We use these properties to conclude the first optimistic algorithms for efficient, max-min fair, rate-based flow control sensitive to priorities.

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Interfacing of a TEM/STEM System to a Computer

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100097818 ◽

1981 ◽

Vol 39 ◽

pp. 250-251

Author(s):

P. Hagemann

Keyword(s):

Image Analysis ◽

Transmission Rate ◽

Analytical Electron Microscopy ◽

Signal Beam ◽

Automated Image Analysis ◽

Beam Deflection ◽

External Control ◽

Computer Input ◽

Instrument Control ◽

Data Acquisition And Processing

The use of computers in the analytical electron microscopy today shows three different trends (1) automated image analysis with dedicated computer systems, (2) instrument control by microprocessors and (3) data acquisition and processing e.g. X-ray or EEL Spectroscopy.While image analysis in the T.E.M. usually needs a television chain to get a sequential transmission suitable as computer input, the STEM system already has this necessary facility. For the EM400T-STEM system therefore an interface was developed, that allows external control of the beam deflection in TEM as well as the control of the STEM probe and video signal/beam brightness on the STEM screen.The interface sends and receives analogue signals so that the transmission rate is determined by the convertors in the actual computer periphery.

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