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RAMS
In engineering, RAMS (reliability, availability, maintainability and safety) Norwegian University of Science and Technology is used to characterize a product or system: * – as ability to perform a specific function and may be given as design reliability or operational reliability. * , – as ability to keep a functioning state in the given environment. * |
Reliability Engineering
Reliability engineering is a sub-discipline of systems engineering that emphasizes the ability of equipment to function without failure. Reliability describes the ability of a system or component to function under stated conditions for a specified period of time. Reliability is closely related to availability, which is typically described as the ability of a component or system to function at a specified moment or interval of time. The reliability function is theoretically defined as the probability of success at time t, which is denoted R(t). This probability is estimated from detailed (physics of failure) analysis, previous data sets or through reliability testing and reliability modelling. Availability, testability, maintainability and maintenance, repair and operations, maintenance are often defined as a part of "reliability engineering" in reliability programs. Reliability often plays the key role in the cost-effectiveness of systems. Reliability engineering deals with the p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Availability
In reliability engineering, the term availability has the following meanings: * The degree to which a system, subsystem or equipment is in a specified operable and committable state at the start of a mission, when the mission is called for at an unknown, ''i.e.'' a random, time. * The probability that an item will operate satisfactorily at a given point in time when used under stated conditions in an ideal support environment. Normally high availability systems might be specified as 99.98%, 99.999% or 99.9996%. Representation The simplest representation of availability (''A'') is a ratio of the expected value of the uptime of a system to the aggregate of the expected values of up and down time (that results in the "total amont of time" ''C'' of the observation window) : A = \frac = \frac Another equation for availability (''A'') is a ratio of the Mean Time To Failure (MTTF) and Mean Time To Repair (MTTR), or : A = \frac = \frac If we define the status function X(t) as : X( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maintainability
In engineering, maintainability is the ease with which a product can be maintained to: * correct defects or their cause, * Repair or replace faulty or worn-out components without having to replace still working parts, * prevent unexpected working conditions, * maximize a product's useful life, * maximize efficiency, reliability, and safety, * meet new requirements, * make future maintenance easier, or * cope with a changing environment. In some cases, maintainability involves a system of continuous improvement - learning from the past to improve the ability to maintain systems, or improve the reliability of systems based on maintenance experience. In telecommunication and several other engineering fields, the term maintainability has the following meanings: * A characteristic of design and installation, expressed as the probability that an item will be retained in or restored to a specified condition within a given period of time, when the maintenance is performed by prescribed p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reliability, Availability And Serviceability
Reliability, availability and serviceability (RAS), also known as reliability, availability, and maintainability (RAM), is a computer hardware engineering term involving reliability engineering, high availability, and serviceability design. The phrase was originally used by International Business Machines ( IBM) as a term to describe the robustness of their mainframe computers. Computers designed with higher levels of RAS have many features that protect data integrity and help them stay available for long periods of time without failure This data integrity and uptime is a particular selling point for mainframes and fault-tolerant systems. Definitions While RAS originated as a hardware-oriented term, systems thinking has extended the concept of reliability-availability-serviceability to systems in general, including software. * ''Reliability'' can be defined as the probability that a system will produce correct outputs up to some given time ''t''. Reliability is enhanced by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Systems Engineering
Systems engineering is an interdisciplinary field of engineering and engineering management that focuses on how to design, integrate, and manage complex systems over their enterprise life cycle, life cycles. At its core, systems engineering utilizes systems thinking principles to organize this body of knowledge. The individual outcome of such efforts, an engineered system, can be defined as a combination of components that work in synergy to collectively perform a useful Function (engineering), function. Issues such as requirements engineering, reliability, logistics, coordination of different teams, testing and evaluation, maintainability and many other Discipline (academia), disciplines necessary for successful system design, development, implementation, and ultimate decommission become more difficult when dealing with large or complex projects. Systems engineering deals with work-processes, optimization methods, and risk management tools in such projects. It overlaps technical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dependability
In systems engineering, dependability is a measure of a system's availability, reliability, maintainability, and in some cases, other characteristics such as durability, safety and security. In real-time computing, dependability is the ability to provide services that can be trusted within a time-period.A. Avizienis, J.-C. Laprie, Brian Randell, and C. Landwehr,Basic Concepts and Taxonomy of Dependable and Secure Computing" IEEE Transactions on Dependable and Secure Computing, vol. 1, pp. 11-33, 2004. The service guarantees must hold even when the system is subject to attacks or natural failures. The International Electrotechnical Commission (IEC), via its Technical Committee TC 56 develops and maintains international standards that provide systematic methods and tools for dependability assessment and management of equipment, services, and systems throughout their life cycles. The IFIP Working Group 10.4 on "Dependable Computing and Fault Tolerance" plays a role in synthesizing t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reliability-centered Maintenance
Reliability-centered maintenance (RCM) is a concept of maintenance planning to ensure that systems continue to do what their user require in their present operating context. Successful implementation of RCM will lead to increase in cost effectiveness, reliability, machine uptime, and a greater understanding of the level of risk that the organization is managing. Context It is generally used to achieve improvements in fields such as the establishment of safe minimum levels of maintenance, changes to operating procedures and strategies and the establishment of capital maintenance regimes and plans. Successful implementation of RCM will lead to increase in cost effectiveness, machine uptime, and a greater understanding of the level of risk that the organization is managing. John Moubray characterized RCM as a process to establish the safe minimum levels of maintenance. This description echoed statements in the Nowlan and Heap report from United Airlines. It is defined by the tech ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Engineering
Engineering is the use of scientific method, scientific principles to design and build machines, structures, and other items, including bridges, tunnels, roads, vehicles, and buildings. The discipline of engineering encompasses a broad range of more specialized List of engineering branches, fields of engineering, each with a more specific emphasis on particular areas of applied mathematics, applied science, and types of application. See glossary of engineering. The term ''engineering'' is derived from the Latin ''ingenium'', meaning "cleverness" and ''ingeniare'', meaning "to contrive, devise". Definition The American Engineers' Council for Professional Development (ECPD, the predecessor of Accreditation Board for Engineering and Technology, ABET) has defined "engineering" as: The creative application of scientific principles to design or develop structures, machines, apparatus, or manufacturing processes, or works utilizing them singly or in combination; or to construct o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Risk Assessment
Broadly speaking, a risk assessment is the combined effort of: # identifying and analyzing potential (future) events that may negatively impact individuals, assets, and/or the environment (i.e. hazard analysis); and # making judgments "on the tolerability of the risk on the basis of a risk analysis" while considering influencing factors (i.e. risk evaluation). Put in simpler terms, a risk assessment determines possible mishaps, their likelihood and consequences, and the tolerances for such events. The results of this process may be expressed in a quantitative or qualitative fashion. Risk assessment is an inherent part of a broader risk management strategy to help reduce any potential risk-related consequences. Need Individual risk assessment Risk assessment are done in individual cases, including patient and physician interactions. Individual judgements or assessments of risk may be affected by psychological, ideological, religious or otherwise subjective factors, which impa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Safety Integrity Level
Safety integrity level (SIL) is defined as the relative level of risk-reduction provided by a safety function, or to specify a target level of risk reduction. In simple terms, SIL is a measurement of performance required for a safety instrumented function (SIF). The requirements for a given SIL are not consistent among all of the functional safety standards. In the functional safety standards based on the IEC 61508 standard, four SILs are defined, with SIL 4 the most dependable and SIL 1 the least. The applicable SIL is determined based on a number of quantitative factors in combination with qualitative factors such as development process and safety life cycle management. Assignment Assignment of SIL is an exercise in risk analysis where the risk associated with a specific hazard, that is intended to be protected against by a SIF, is calculated without the beneficial risk reduction effect of the SIF. That unmitigated risk is then compared against a tolerable risk target. The di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Failure Rate
Failure rate is the frequency with which an engineered system or component fails, expressed in failures per unit of time. It is usually denoted by the Greek letter λ (lambda) and is often used in reliability engineering. The failure rate of a system usually depends on time, with the rate varying over the life cycle of the system. For example, an automobile's failure rate in its fifth year of service may be many times greater than its failure rate during its first year of service. One does not expect to replace an exhaust pipe, overhaul the brakes, or have major transmission problems in a new vehicle. In practice, the mean time between failures (MTBF, 1/λ) is often reported instead of the failure rate. This is valid and useful if the failure rate may be assumed constant – often used for complex units / systems, electronics – and is a general agreement in some reliability standards (Military and Aerospace). It does in this case ''only'' relate to the flat region of the ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
