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Time-domain finite-difference analysis of electromagnetic scattering and penetration problems
Title
Time-domain finite-difference analysis of electromagnetic scattering and penetration problems.
Creator
Bemmel, Vincent Egbert., Florida Atlantic University, Sadiku, Matthew
Abstract/Description
The complexity involved in using analytical techniques in solving electromagnetic problems can be avoided by simulating Maxwell's differential equations by finite difference equations, which are easily solved by iteration. In this work some algorithms were developed in order to investigate plane waves as they travel through a certain medium and interact with objects, resulting in scattering and/or penetration. The numerical results were found to be in good agreement with analytical results...
Show moreThe complexity involved in using analytical techniques in solving electromagnetic problems can be avoided by simulating Maxwell's differential equations by finite difference equations, which are easily solved by iteration. In this work some algorithms were developed in order to investigate plane waves as they travel through a certain medium and interact with objects, resulting in scattering and/or penetration. The numerical results were found to be in good agreement with analytical results for tractable cases.
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Date Issued
1987
PURL
http://purl.flvc.org/fcla/dt/14422
Subject Headings
Electromagnetic fields, Maxwell's equations
Format
Document (PDF)
unified end-to-end priority strategy for traffic control in an ATM-based broadband ISDN
Title
A unified end-to-end priority strategy for traffic control in an ATM-based broadband ISDN.
Creator
Bemmel, Vincent Egbert., Florida Atlantic University, Ilyas, Mohammad, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
Abstract/Description
In order to guarantee a committed Quality of Service (QoS) to the users of a Broadband Integrated Services Digital Network (B-ISDN), preventive congestion control becomes critical, and is implemented through Call Acceptance Control (CAC) and Usage Parameter Control (UPC) functions. Currently, Asynchronous Transfer Mode (ATM) cells are equipped with a 1-bit Cell Loss Priority (CLP) field, which can be used for service-oriented and/or UPC marking. This creates a conflict, since these two...
Show moreIn order to guarantee a committed Quality of Service (QoS) to the users of a Broadband Integrated Services Digital Network (B-ISDN), preventive congestion control becomes critical, and is implemented through Call Acceptance Control (CAC) and Usage Parameter Control (UPC) functions. Currently, Asynchronous Transfer Mode (ATM) cells are equipped with a 1-bit Cell Loss Priority (CLP) field, which can be used for service-oriented and/or UPC marking. This creates a conflict, since these two marking approaches may have contradicting objectives, and are designed to operate independently. Moreover, by admitting excessive cells as marked traffic, this group is allowed to grow uncontrollably, thereby jeopardizing the QoS committed to other marked cells. This dissertation presents a solution to these problems by proposing a new 4-class priority strategy that unifies the two marking approaches, and is based on a 2-bit CLP field. The impacts of the new priority scheme are triple-fold: (I) For the UPC, a new scheme, the Forgiving Leaky Bucket (FLB), not only carries priorities through subnetwork boundaries, but also has the power of unmarking, i.e. forgiving, previously marked cells, depending on the bandwidth availability in the entering subnetwork. Forgiving will correct access-point bias, a phenomenon observed in internetworked ATM subnetworks of different congestion conditions. (II) At ATM switching nodes, a new space priority scheme is based on a hybrid of the Nested Threshold, and Push-Out cell discarding methods. This scheme is designed for the 4-class priority strategy, and improves the quality of the low priority traffic. (III) In interfacing High Speed Local Area Networks and Metropolitan Area Networks, idle bandwidth due to STM multiplexing is utilized to carry marked excessive cells of connection-oriented variable bit rate traffic, in addition to the service-oriented marking performed at transmitting stations. The resulting stream is then carried through internetworking points, subject to FLB adjustments. As a result, the STM and ATM subnetworks will support a uniform end-to-end priority strategy, essential for a B-ISDN. The proposed impacts are analyzed and compared with conventional implementations, and future directions are indicated.
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Date Issued
1993
PURL
http://purl.flvc.org/fcla/dt/12334
Subject Headings
Integrated services digital networks, Broadband communication systems, Computer networks--Management, Packet switching (Data transmission)
Format
Document (PDF)