A monitor for the laboratory evaluation of control integrity in digital control systems operating in harsh electromagnetic environments

This paper presents a strategy for dynamically monitoring digital controllers in the laboratory for susceptibility to electromagnetic disturbances that compromise control integrity. The integrity of digital control systems operating in harsh electromagnetic environments can be compromised by upsets caused by induced transient electrical signals. Digital system upset is a functional error mode that involves no component damage, can occur simultaneously in all channels of a redundant control computer, and is software dependent. The motivation for this work is the need to develop tools and techniques that can be used in the laboratory to validate and/or certify critical aircraft controllers operating in electromagnetically adverse environments that result from lightning, high-intensity radiated fields (HIRF), and nuclear electromagnetic pulses (NEMP). The detection strategy presented in this paper provides dynamic monitoring of a given control computer for degraded functional integrity resulting from redundancy management errors, control calculation errors, and control correctness/effectiveness errors. In particular, this paper discusses the use of Kalman filtering, data fusion, and statistical decision theory in monitoring a given digital controller for control calculation errors

On the sharpness of the bound for the Local Converse Theorem of p-adic GLprime

We introduce a novel ultrametric on the set of equivalence classes of cuspidal irreducible representations of a general linear group GL(N) over a nonarchimedean local field, based on distinguishability by twisted gamma factors. In the case that N is prime and the residual characteristic is greater than or equal to N/2, we prove that, for any natural number i at most N/2, there are pairs of cuspidal irreducible representations whose logarithmic distance in this ultrametric is precisely i. This implies that, under the same conditions on N, the bound N/2 in the Local Converse Theorem for GL(N) is sharp

Adaptive performance control of computing systems via distributed cooperative control: Application to power management in computing clusters

Proceedings of the 3rd International Conference on Autonomic Computing, ICAC 2006, pp. 165-174.Advanced control and optimization techniques offer a theoretically sound basis to enable self-managing behavior in distributed computing models such as utility computing. To tractably solve the performance management problems of interest, including resource allocation and provisioning in such distributed computing environments, we develop a fully decentralized control framework wherein the optimization problem for the system is first decomposed into sub-problems, and each sub-problem is solved separately by individual controllers to achieve the overall performance objectives. Concepts from optimal control theory are used to implement individual controllers. The proposed framework is highly scalable, naturally tolerates controller failures, and allows for the dynamic addition/removal of controllers during system operation. As a case study, we apply the control framework to minimize the power consumed by a computing cluster subject to a dynamic workload while satisfying the specified quality-of-service goals. Simulations using real-world workload traces show that the proposed technique has very low control overhead, and adapts quickly to both workload variations and controller failures

Distributed cooperative control for adaptive performance management

IEEE Internet Computing, 11(1): pp. 31-39.The authors’ distributed cooperative-control framework uses concepts from optimal control theory to adaptively manage the performance of computer clusters operating in dynamic and uncertain environments. Decomposing the overall performance-management problem into smaller subproblems that individual controllers solve cooperatively allows for the scalable control of large computing systems. The control framework also adapts to controller failures and allows for the dynamic addition and removal of controllers during system operation. This article presents a case study showing how to manage the dynamic power consumed by a computer cluster processing a time-varying Web workload

A computational fluid dynamics approach for optimization of a sensor network

Presented at the 2006 IEEE International Workshop on Measurement Systems for Homeland Security, Contraband Detection and Personal Safety. Alexandria, VA.We optimize the placement of sensors for detecting a nuclear, biological, or chemical (NBC) attack in a dense urban environment. This approach draws from two main areas: (1) computational fluid dynamic (CFD) simulations and (2) sensor placement algorithms. The main objective was to minimize detection time of a NBC sensor network for attacks on a generic urban environment. To this end we conducted simulations in the generic urban environment using thirty-three (33) unique attack locations, thirty-three (33) candidate sensor locations, prevailing wind conditions, and the properties of the chemical agent, chlorine gas. A total of ninety-nine (99) simulated attack scenarios were created (three sets of thirty-three unique attack simulations) and used for optimization. Simulated surrogate agent concentration data were collected at each candidate sensor location as a function of time. The integration of this concentration data with respect to time was used to calculate the ”consumption” of the network and the sensor placement algorithm minimized consumption to the network while minimizing the number of sensors placed. Our results show how a small number of properly placed sensors (eight(8), in our case) provides the best achievable coverage (additional sensors do not help)

Social Gerontology- Integrative and Territorial Aspects: A Citation Analysis of Subject Scatter and Database Coverage

To determine the mix of resources used in social gerontology research, a citation analysis was conducted. A representative sample of citations was selected from three prominent gerontology journals and information was added to determine subject scatter and database coverage for the cited materials. Results indicate that a significant portion of gerontology research, even from a social science perspective, relies roughly equally on medical resources as it does social science resources. Furthermore, there is a small but defined core of literature constituting scholarly “territory” unique to gerontology. Analysis of database indexing indicated that broad, interdisciplinary databases provide more comprehensive coverage of the cited materials than do subject-specific databases

Control of Hopping Height for a One-Legged Hopping Machine

The control of the hopping height in a one-legged machine is studied. The general aim is to decrease sensitivity of the hopping height to drifts in the machine's parameters. The proposed approach combines a near-inverse controller which uses height feedback, with a recursive least-squares parameter estimator which continually tunes the controller. The paper presents the mechanical design of the hopping leg, as well as simulations of its performance in tracking a piecewise-constant height reference. These simulations suggest that the resulting algorithm is both computationally feasible and robust to disturbances and drifts. 1. Introduction The one-legged hopping machine [2,5-10,12] consists of a body and a single springy leg which articulates with respect to the body. The primary role of a controller for the machine is to dynamically balance the body (i.e. keep the machine from falling over). As a secondary role, the controller is to maintain the desirable hopping height and horizontal ..