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Microbivores: Artificial Mechanical Phagocytes using Digest and Discharge Protocol
"... A peer-reviewed electronic ..."
Perspectives on Redundancy: Applications to Software Certification
- IEEE Proc. HICSS, (Testing and Certification of Trustworthy Systems Minitrack), Big Island
, 2005
"... Redundancy is a feature of systems that arises by design or as an accidental byproduct of design, and can be used to detect, diagnose or correct errors that occur in systems operations. While it is usually investigated in the con-text of fault tolerance, one can argue that it is in fact an intrinsic ..."
Abstract
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Cited by 3 (2 self)
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Redundancy is a feature of systems that arises by design or as an accidental byproduct of design, and can be used to detect, diagnose or correct errors that occur in systems operations. While it is usually investigated in the con-text of fault tolerance, one can argue that it is in fact an intrinsic feature of a system that can be analyzed on its own without reference to any fault tolerance capability. In this paper, we submit three alternative views of redun-dancy, which we propose to analyze to gain a better un-derstanding of redundancy; we also explore means to use this understanding to enhance the design of fault tolerant systems.
Towards Verifiable Adaptive Control for Safety Critical Applications
, 2005
"... requirements for the degree of ..."
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KABINENTECHNOLOGIE UND MULTIFUNKTIONALE BRENNSTOFFZELLE
"... Zusammenfassung Summary In the light tower project 'cabin technologies and multi functional fuel cell' in the frame of the Hamburg Aviation Cluster, the application of a fuel cell and the connected innovations for cabin technologies are investigated for use in an aircraft. For the multi f ..."
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Zusammenfassung Summary In the light tower project 'cabin technologies and multi functional fuel cell' in the frame of the Hamburg Aviation Cluster, the application of a fuel cell and the connected innovations for cabin technologies are investigated for use in an aircraft. For the multi functional fuel cell the integration of the system in an aircraft environment is done in a lab where it is tested according to airborne requirements. In the second part of the project selected cabin systems and their interfaces to the fuel cell system are under investigation. New system architectures for use of the fuel cell products water and power and also air filters for the application of higher air circulation rates are developed. On this later part this paper will focus on. The project Energy optimized Cabin Systems deals with three aspects to reduce mass of the electrical system, to foster aircraft efficiency. These aspects are new 115 VAC architectures on future smaller civil aircraft, higher voltages and power management. In the scope of the project a wide set of architectures were analyzed and results showed, that in many cases decentralized architectures are lighter and more flexible on small aircraft than conventional centralized implementations. Analysis on higher voltages unveiled the promising HVDC approach, which allows weight savings not just in wiring but also in equipment. Power management, which shall permit (nearly) full usage of every wire, has the advantage of being installable on flying aircraft, was the last aspect investigated for weight savings in the electrical system. Another way to enhance the energy efficiency and cabin comfort of future aircraft is to increase the amount of recirculation air in the environmental control system. However, high rates of recirculation air demand for the separation of accumulating CO 2 emitted by the passengers and crew. Among several options the most promising way to realize a CO 2 separation unit successfully is using a solid adsorber, as a lightweight, simple separation unit with low overall energy consumption. The newly developed aerogel adsorbent, which is a amino functionalised silica aerogel, possesses a very high adsorption capacity at low CO 2 concentrations (0.047 g/g) even in the presence of moisture, whereas it also able to remove not only CO 2 but also water and ethanol. Finally, the ability to be regenerated at mild conditions will lower the energy consumption of an aircraft.
Abstract
"... Redundancy is a feature of systems that arises by design or as an accidental byproduct of design, and can be used to detect, diagnose or correct errors that occur in systems operations. While it is usually investigated in the context of fault tolerance, one can argue that it is in fact an intrinsic ..."
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Redundancy is a feature of systems that arises by design or as an accidental byproduct of design, and can be used to detect, diagnose or correct errors that occur in systems operations. While it is usually investigated in the context of fault tolerance, one can argue that it is in fact an intrinsic feature of a system that can be analyzed on its own without reference to any fault tolerance capability. In this paper, we submit three alternative views of redundancy, which we propose to analyze to gain a better understanding of redundancy; we also explore means to use this understanding to enhance the design of fault tolerant systems.
Development of a Normative Package for Safety-Critical Software Using Formal Regulatory Requirements
"... The important tasks in requirement engineering are resolving requirements inconsistencies between regulators and developers of safety-critical computer systems, and the validation of regulatory requirements. This paper proposes a new approach to the regulatory process, including formulating requi ..."
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The important tasks in requirement engineering are resolving requirements inconsistencies between regulators and developers of safety-critical computer systems, and the validation of regulatory requirements. This paper proposes a new approach to the regulatory process, including formulating requirements and elaborating methods for their assessment. We address the differences between prescriptive and nonprescriptive regulation, and suggest a middle approach. Also introduced is the notion of a normative package as the collection of documents to be used by a regulator and provided to a developer. It is argued that the normative package should include not only regulatory requirements but also methods of their assessment. We propose the use of formal regulatory requirements as a basis for development of software assessment methods. This approach is illustrated with examples of requirements for protecting computer control systems against unauthorized access, using the Z notation as the method of formalization.
Keywords Recoverability Preservation: A Measure of Last Resort
"... Abstract. Traditionally, it is common to distinguish between three broad families of methods for dealing with the presence and manifestation of faults in digital (hardware or software) systems: Fault Avoidance, Fault Removal and Fault Tolerance. We focus on fault tolerance and submit that current te ..."
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Abstract. Traditionally, it is common to distinguish between three broad families of methods for dealing with the presence and manifestation of faults in digital (hardware or software) systems: Fault Avoidance, Fault Removal and Fault Tolerance. We focus on fault tolerance and submit that current techniques of fault tolerance would benefit from a better undersdtanding of recoverability preservation, i.e. a system’s ability to preserve recoverability even when / if it does not preserve correctness. In this extended abstract, we briefly introduce the concept of recoverability preservation, discuss some preliminary characterizations of it, then explore possible applications thereof.
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, 2002
"... This Report includes data that shall not be disclosed outside the Government and shall not be duplicated, used, or disclosed in whole or in part for any purpose other than to evaluate this Report. This restriction does not limit the right of the Government to use information contained in this Report ..."
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This Report includes data that shall not be disclosed outside the Government and shall not be duplicated, used, or disclosed in whole or in part for any purpose other than to evaluate this Report. This restriction does not limit the right of the Government to use information contained in this Report if it is proprietary data contained herein, if obtained from another source without restriction. The data subject to this restriction are contained in all sheets of this Report. The proprietary data contained herein, if disclosed to the public, would affect ISR’s competitive position in obtaining business; therefore, it is considered to be exempt from public release under the Freedom of Information Act (5 USC §552, as amended), paragraph (b)(4). IVVNN-LITREV-F002-UNCLASS-111202
Modeling Redundancy: Quantitative and Qualitative Models
, 2007
"... Redundancy is a system property that generally refers to duplication of state information or system function. While redundancy is usually investigated in the context of fault tolerance, one can argue that it is in fact an intrinsic feature of a system that can be analyzed on its own without refer-en ..."
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Redundancy is a system property that generally refers to duplication of state information or system function. While redundancy is usually investigated in the context of fault tolerance, one can argue that it is in fact an intrinsic feature of a system that can be analyzed on its own without refer-ence to fault tolerance. Redundancy may arise by design, generally to support fault tolerance, or as a natural byprod-uct of design, and is usually unexploited. In this paper, we tentatively explore observable forms of redundancy, as well as mathematical models that capture them.
Relational Characterizations of System Fault Tolerance
, 2004
"... Fault tolerance is the ability of a system to continue delivering its services after faults have caused errors. We have argued, in the past, that complex and/or critical systems are best validated by a wide range of methods, including proving, testing, and fault tolerance; we have also argued that i ..."
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Fault tolerance is the ability of a system to continue delivering its services after faults have caused errors. We have argued, in the past, that complex and/or critical systems are best validated by a wide range of methods, including proving, testing, and fault tolerance; we have also argued that in order to use these methods in concert, we need to cast them in a common framework. In this paper, we present mathematical characterizations of fault tolerance properties, using a relational calculus.
