Bruce M. McMillin

Automated highway systems

Currently, intelligent transportation systems are being developed and implemented in various forms. Advanced traffic management systems (ATMS), automatic traveler information systems (ATIS) and driver support systems are all a reality today. However, many challenges remain on the road to realizing a fully automated highway system (AHS). The complexity of developing large distributed systems such as AHS has raised warning flags in the computer science community. Unexpected complex interactions between the software and hardware can induce errors that can be fatal. The authors argue that these issues should provide a cautionary note to practicing engineers before deploying a fully automated highway system.

Power transmission control using distributed max-flow

Existing maximum flow algorithms use one processor for all calculations or one processor per vertex in a graph to calculate the maximum possible flow through a graphs vertices. This is not suitable for practical implementation. We extend the max-flow work of Goldberg and Tarjan to a distributed algorithm to calculate maximum flow where the number of processors is less than the number of vertices in a graph. Our algorithm is applied to maximizing electrical flow within a power network where the power grid is modeled as a graph. Error detection measures are included to detect problems in a simulated power network. We show that our algorithm is successful in executing quickly enough to prevent catastrophic power outages.

Composite stock cutting through simulated annealing

This paper explores the use of Simulated Annealing as an optimization technique for the problem of Composite Material Stock Cutting. The shapes are not constrained to be convex polygons or even regular shapes. However, due to the composite nature of the material, the orientation of the shapes on the stock is restricted. For placements of various shapes, we show how to determine a cost function, annealing parameters and performance.

The maximum flow algorithm applied to the placement and distributed steady-state control of UPFCs

The bulk power system is one of the largest man-made networks and its size makes control an extremely difficult task. This paper presents a method to control a power network using UPFCs set to levels determined by a maximum flow (max-flow) algorithm. The graph-theory-based max-flow is applied to the power system for UPFC placement and scheduling. A distributed version of max-flow is described to coordinate the actions of the UPFCs distributed in a power network. Two sample power systems were tested using max-flow for UPFC placement and settings. The resulting system characteristics are examined over all single-line contingencies and the appropriateness of the maximum flow algorithm for power flow control is discussed.

Reliable distributed sorting through the application-oriented fault tolerance paradigm

The design and implementation of a reliable version of the distributed bitonic sorting algorithm using the application-oriented fault tolerance paradigm on a commercial multicomputer is described. Sorting assertions in general are discussed and the bitonic sort algorithm is introduced. Faulty behavior is discussed and a fault-tolerant parallel bitonic sort developed using this paradigm is presented. The error coverage and the response of the fault-tolerant algorithm to faulty behavior are presented. Both asymptotic complexity and the results of run-time experimental measurements on an Ncube multicomputer are given. The authors demonstrate that the application-oriented fault tolerance paradigm is applicable to problems of a noniterative nature. >

Structured object-oriented co-analysis/co-design of hardware/software for the FACTS power system

There are several approaches to the hardware/software design in embedded systems, ranging from the traditional sequential methods which focus on the determination of the hardware architecture prior to software design, to newer object-oriented approaches that attempt to apply software engineering methods to hardware design without a systematic process. This paper discusses a structured object-oriented methodology for the integrated co-analysis and co-design of hardware/software systems using an extended high order object-oriented modeling technique (HOOMT). This methodology offers a uniform method for hardware and software developers to jointly develop the specifications for and partitioning of the hardware and software components of a system, as well as developing the interfaces between components, and allows easy design migration of components between hardware and software. In this paper it is applied to the co-analysis/co-design of the hardware and software of a simulated advanced power grid control system.

Run-time security evaluation (RTSE) for distributed applications

Formal security specifications for a distributed application can be checked for compliance at run-time using executable security assertions. We propose the run-time security evaluation (RTSE) method which makes use of histories/traces of events, assertions and operational evaluation in the distributed environment to ensure the security specifications for the application are fulfilled at run-time. A model problem is used to aid in developing the security requirements formally.

Fault-tolerant distributed deadlock detection/resolution

In an unreliable distributed system, faulty processors may prevent a deadlock detection algorithm from properly detecting deadlocks. However, few of the algorithms proposed in the literature address the issue of handling process failures in a distributed system. This paper proposes a fault-tolerant distributed deadlock detection algorithm which integrates a priority-based probe algorithm with a PMC-based diagnosis model. This algorithm detects deadlock cycles as well as identifies process failures under a bounded number of failures in a deadlock cycle by using extended probe messages that contain additional information about faulty processors.<<ETX>>

Personal computing for the visually impaired

The problem of providing feedback from the computer to a visually impaired user is examined. The use of traditional tactile input and output (Braille) is described. The limitations of voice output are discussed, and difficulties posed by complicated screen formats and screen review are considered.<<ETX>>

A general method for maximizing the error-detecting ability of distributed algorithms

The bound on component failures and their spatial distribution govern the fault tolerance of any candidate error-detecting algorithm. For distributed memory multiprocessors, the specific algorithm and the topology of the processor interconnection network define these bounds. This paper introduces the maximal fault index, derived from the system topology and local communication patterns, to demonstrate how a maximal number of simultaneous component failures can be tolerated for a particular interconnection network and error-detecting algorithm. The index is used to design a mapping of processes to processor groups such that the error-detecting ability of the algorithm is preserved for certain multiple simultaneous processor failures.