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Unavailable Name
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%. The converse, unavailability, is 1 minus the availability. 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 amount 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 Between Failure (MTBF), or : ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reliability Engineering
Reliability engineering is a sub-discipline of systems engineering that emphasizes the ability of equipment to function without failure. Reliability is defined as the probability that a product, system, or service will perform its intended function adequately for a specified period of time, OR will operate in a defined environment without failure. 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. In practice, it is calculated using different techniques, and its value ranges between 0 and 1, where 0 indicates no probability of success while 1 indicates definite success. This probability is estimated from detailed (physics of failure) analysis, previous data sets, or through reliability testing and reliability modeling. Availability, testability, maintainability, and maintenance ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spare Part
A spare part, spare, service part, repair part, or replacement part, is an interchangeable part that is kept in an inventory and used for the repair or Refurbishment (electronics), refurbishment of defective equipment/units. Spare parts are an important feature of logistics engineering and supply chain management, often comprising dedicated spare parts management systems. Spare parts are an outgrowth of the industrial development of interchangeable parts and mass production. In an industrial environment, spare parts are described in several manner to distinguish key features of various spare parts. The following describes spare part types and their typically functionality. 1. Capital parts are spare parts which, although acknowledged to have a long life or a small chance of failure, would cause a long shutdown of equipment because it would take a long time to get a replacement for them. Capital parts are typically repaired or replaced during planned overhauls/scheduled inspect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High Availability
High availability (HA) is a characteristic of a system that aims to ensure an agreed level of operational performance, usually uptime, for a higher than normal period. There is now more dependence on these systems as a result of modernization. For example, to carry out their regular daily tasks, hospitals and data centers need their systems to be highly available. Availability refers to the ability of the user to access a service or system, whether to submit new work, update or modify existing work, or retrieve the results of previous work. If a user cannot access the system, it is considered ''unavailable from the user's perspective''. The term '' downtime'' is generally used to refer to describe periods when a system is unavailable. Resilience High availability is a property of network resilience, the ability to "provide and maintain an acceptable level of service in the face of faults and challenges to normal operation." Threats and challenges for services can range from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fault Reporting
Fault reporting is a maintenance concept that increases operational availability and that reduces operating cost by three mechanisms: * Reduce labor-intensive diagnostic evaluation * Eliminate diagnostic testing down-time * Provide notification to management for degraded operation That is a prerequisite for condition-based maintenance. Active redundancy can be integrated with fault reporting to reduce the down time to a few minutes per year. History Formal maintenance philosophies are required by organizations whose primary responsibility is to ensure systems are ready when expected, such as space agencies and military. Labor-intensive planned maintenance began during the rise of the Industrial Revolution and depends upon periodic diagnostic evaluation based upon calendar dates, distance, or use. The intent is to accomplish diagnostic evaluations that indicate when maintenance is required to prevent inconvenience and safety issues that will occur when critical equipment fai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Condition-based Maintenance
Predictive maintenance techniques are designed to help determine the condition of in-service equipment in order to estimate when maintenance should be performed. This approach claims more cost savings over routine or time-based preventive maintenance, because tasks are performed only when warranted. Thus, it is regarded as condition-based maintenance carried out as suggested by estimations of the degradation state of an item. The main appeal of predictive maintenance is to allow convenient scheduling of corrective maintenance, and to prevent unexpected equipment failures. By taking into account measurements of the state of the equipment, maintenance work can be better planned (spare parts, people, etc.) and what would have been "unplanned stops" are transformed to shorter and fewer "planned stops", thus increasing plant availability. Other potential advantages include increased equipment lifetime, increased plant safety, fewer accidents with negative impact on environment, and o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spurious Trip Level
Spurious trip level (STL) is defined as a discrete level for specifying the spurious trip requirements of safety functions to be allocated to safety systems. An STL of 1 means that this safety function has the highest level of spurious trips. The higher the STL level the lower the number of spurious trips caused by the safety system. There is no limit to the number of spurious trip levels. Safety functions and systems are installed to protect people, the environment and for asset protection. A safety function should only activate when a dangerous situation occurs. A safety function that activates without the presence of a dangerous situation (e.g., due to an internal failure) causes economic loss. The spurious trip level concept represents the probability that safety function causes a spurious (unscheduled) trip. The STL is a metric that is used to specify the performance level of a safety function in terms of the spurious trips it potentially causes. Typical safety systems that ben ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of System Quality Attributes
Within systems engineering, quality attributes are realized non-functional requirements used to evaluate the performance of a system. These are sometimes named architecture characteristics, or "ilities" after the suffix many of the words share. They are usually architecturally significant requirements that require architects' attention. In software architecture, these attributed are known as "architectural characteristic" or non-functional requirements. Note that it's software architects' responsibility to match these attributes with business requirements and user requirements. Note that synchronous communication between software architectural components, entangles them and they must share the same architectural characteristics. Quality attributes Notable quality attributes include: * accessibility * accountability * accuracy * adaptability * administrability * affordability * agility * auditability * autonomy * availability * compatibility * composability * con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Safety Engineering
Safety engineering is an engineering Branches of science, discipline which assures that engineered systems provide acceptable levels of safety. It is strongly related to industrial engineering/systems engineering, and the subset system safety engineering. Safety engineering assures that a life-critical system behaves as needed, even when components Failure, fail. Analysis techniques Analysis techniques can be split into two categories: Qualitative research, qualitative and Quantitative research, quantitative methods. Both approaches share the goal of finding causal dependencies between a hazard on system level and failures of individual components. Qualitative approaches focus on the question "What must go wrong, such that a system hazard may occur?", while quantitative methods aim at providing estimations about probabilities, rates and/or severity of consequences. The complexity of the technical systems such as Improvements of Design and Materials, Planned Inspections, Fool-pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reliability Engineering
Reliability engineering is a sub-discipline of systems engineering that emphasizes the ability of equipment to function without failure. Reliability is defined as the probability that a product, system, or service will perform its intended function adequately for a specified period of time, OR will operate in a defined environment without failure. 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. In practice, it is calculated using different techniques, and its value ranges between 0 and 1, where 0 indicates no probability of success while 1 indicates definite success. This probability is estimated from detailed (physics of failure) analysis, previous data sets, or through reliability testing and reliability modeling. Availability, testability, maintainability, and maintenance ... [...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] |
Generating Availability Data System
The Generating Availability Data System (GADS) is a database produced by the North American Electric Reliability Corporation (NERC). It includes annual summary reports comprising the statistics for power stations in the United States and Canada. GADS is the main source of power station outage data in North America. This reporting system, initiated by the electric utility industry in 1982, expands and extends the data collection procedures begun by the industry in 1963. NERC GADS is recognized today as a valuable source of reliability, availability, and maintainability (RAM) information.North American Electric Reliability Corporation's (NERC) Generating Availability Data System (GADS) Data Reporting Instructions (DRI). This information, collected for both total unit and major equipment groups, is used by analysts industry-wide in numerous applications. GADS maintains complete operating histories on more than 5,800 generating units representing 71% of the installed generating capac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
North American Electric Reliability Corporation
The North American Electric Reliability Corporation (NERC) is a nonprofit corporation based in Atlanta, Georgia, and formed on March 28, 2006, as the successor to the North American Electric Reliability Council (also known as NERC). The original NERC was formed on June 1, 1968, by the electric utility industry to promote the reliability and adequacy of bulk power transmission in the electric utility systems of North America. NERC's mission states that it "is to assure the effective and efficient reduction of risks to the reliability and security of the grid". NERC oversees six regional reliability entities and encompasses all of the interconnected power systems of Canada and the contiguous United States, as well as a portion of the Mexican state of Baja California. NERC's major responsibilities include working with all stakeholders to develop standards for power system operation, monitoring and enforcing compliance with those standards, assessing resource adequacy, and prov ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
