Cyber-Physical Systems Module 1

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Questions and Answers

What is the term for a system's ability to deliver service that can justifiably be trusted?

Dependability

What is the process of determining whether a realization meets its specification?

Validation

What is the term for a transition from proper to improper service?

System failure

What is the term for that part of the system state that may cause a subsequent failure?

Error Signup and view all the answers

What is the term for the adjudged or hypothesized cause of an error?

Fault Signup and view all the answers

What are the four techniques for ensuring dependability?

Fault prevention, fault tolerance, fault removal, and fault forecasting Signup and view all the answers

What is the term for the readiness for correct service?

Availability Signup and view all the answers

What is the term for a system consisting of a computer system, a controlled object, and possibly interacting humans?

Cyber-physical system Signup and view all the answers

What is the primary characteristic of reliability in a system?

Continuous delivery of service Signup and view all the answers

What is the primary measure of Safety in a system?

Time to catastrophic failure Signup and view all the answers

What is the primary goal of model validation in system modeling?

To ensure the model accurately represents the system or specifies the intended model Signup and view all the answers

What are the three primary methods of model validation?

Measurements, Theoretical results, Insight of experts Signup and view all the answers

What is the primary characteristic of Performability in a system?

Quantifying system performance considering faults Signup and view all the answers

What is the primary goal of Dependability measures in a system?

To find a compromise between contrasting measures (e.g., safety and availability) Signup and view all the answers

What is the primary characteristic of Maintainability in a system?

Ability to undergo modifications and repairs Signup and view all the answers

What is the primary goal of Coverage in a system?

Measuring the effectiveness of fault tolerance techniques Signup and view all the answers

Study Notes

System Definition

A system consists of a computer system (cyber system), a controlled object (physical system), and possibly interacting humans.
A collection of hardware, networks, operating systems, and application software that is intended to be dependable, secure, survivable, or have predictable performance.

System Properties

Valid: Able to effect or accomplish what is designed or intended.
Specification: A description of what a system is supposed to do.
Realization: A description of what a system is and does.
Validation: The process of determining whether a realization meets its specification.

Dependability

Dependability: Ability to deliver service that can justifiably be trusted, ability to avoid service failures that are more frequent and more severe than is acceptable.
System service: Classified as proper if it is delivered as specified; otherwise, it is improper.
System failure: A transition from proper to improper service.
System restoration: A transition from improper to proper service.

Error, Failure, and Fault

Error: That part of the system state that may cause a subsequent failure.
Failure: Occurs when an error reaches the service interface and alters the service.
Fault: The adjudged or hypothesized cause of an error; active when it produces an error, otherwise dormant.

Techniques for Dependability

Fault prevention: Preventing the occurrence or introduction of faults.
Fault tolerance: Delivering correct service in the presence of faults.
Fault removal: Reducing the number or severity of faults.
Fault forecasting: Estimating the present number, the future incidence, and the likely consequences of faults.

Dependability Measures

Availability: Readiness for correct service, quantifying the alternation between deliveries of proper and improper service.
Reliability: A measure of the continuous delivery of service.
Safety: A measure of the time to catastrophic failure.
Time to Failure: A measure of the time to failure from the last restoration.
Maintainability: The ability to undergo modifications and repairs.
Coverage: The measure of the effectiveness of a given fault tolerance technique.

Performance and Performability

Performance: How well a system performs, provided that service is proper.
Performability: Quantifies how well a system performs, taking into account behavior due to the occurrence of faults.

Validation Methods

Model validation: The process of making sure that the model built is correct, accurately representing the system or the model specified.
Validation methods: Measurements, theoretical results, and insight of experts.

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Description

This quiz covers the introduction to Cyber-Physical Systems, including its components, specifications, and realization. Learn about dependable, secure, and predictable performance of systems.