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Availability (system)
Availability is the probability that a system will work as required when required during the period of a mission. The mission could be the 18-hour span of an aircraft flight. The mission period could also be the 3 to 15-month span of a military deployment. Availability includes non-operational periods associated with reliability, maintenance, and logistics. This is measured in terms of nines. Five-9's (99.999%) means less than 5 minutes when the system is not operating correctly over the span of one year. Availability is only meaningful for supportable systems. As an example, availability of 99.9% means nothing after the only known source stops manufacturing a critical replacement part. Definition There are two kinds of availability. * Operational * Predicted Operational availability is presumed to be the same as predicted availability until after operational metrics become available. Availability Operational availability is based on observations after at least one system h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Military Deployment
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Military deployment is the movement of armed forces and their logistical support infrastructure around the world. Notable deployments and deployment forces include: * Egyptian Rapid deployment forces * Pakistan Armed Forces deployments * Deployments of the United States Military * Deployments of the French military See also * Rapid Deployment Force * Expeditionary warfare Expeditionary warfare is a military invasion of a foreign territory, especially away from established bases. Expeditionary forces were in part the antecedent of the modern concept of rapid deployment forces. Traditionally, expeditionary forces ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High Availability
High availability (HA) is a characteristic of a system which aims to ensure an agreed level of operational performance, usually uptime, for a higher than normal period. Modernization has resulted in an increased reliance on these systems. For example, hospitals and data centers require high availability of their systems to perform routine daily activities. Availability refers to the ability of the user community to obtain a service or good, access the system, whether to submit new work, update or alter existing work, or collect the results of previous work. If a user cannot access the system, it is – from the user's point of view – ''unavailable''. Generally, the term '' downtime'' is used to refer to periods when a system is unavailable. Principles There are three principles of systems design in reliability engineering which can help achieve high availability. # Elimination of single points of failure. This means adding or building redundancy into the system so tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brassboard
A brassboard or brass board is an experimental or demonstration test model, intended for field testing outside the laboratory environment. A brassboard follows an earlier prototyping stage called a breadboard. A brassboard contains both the functionality and approximate physical configuration of the final operational product. Unlike breadboards, brassboards typically recreate geometric and dimensional constraints of the final system which are critical to its performance, as is the case in radio frequency systems. While representative of the physical layout of the production-grade product, a brassboard will not necessarily incorporate all final details, nor represent the physical size and quality level of the final deliverable product. Exact definition of a brassboard depends on the industry and has changed with time. A 1992 guide book on proposal preparation defined a brassboard ''or'' a breadboard as "a laboratory or shop working model that may or may not look like the final produc ... [...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 b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Condition-based Maintenance
The technical meaning of maintenance involves functional checks, servicing, repairing or replacing of necessary devices, equipment, machinery, building infrastructure, and supporting utilities in industrial, business, and residential installations. Over time, this has come to include multiple wordings that describe various cost-effective practices to keep equipment operational; these activities occur either before or after a failure. Definitions Maintenance functions can defined as maintenance, repair and overhaul (MRO), and MRO is also used for maintenance, repair and operations. Over time, the terminology of maintenance and MRO has begun to become standardized. The United States Department of Defense uses the following definitions:Federal Standard 1037C and from MIL-STD-188 and from the Department of Defense Dictionary of Military and Associated Terms * Any activity—such as tests, measurements, replacements, adjustments, and repairs—intended to retain or restore a func ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planned Maintenance System
Planning is the process of thinking regarding the activities required to achieve a desired goal. Planning is based on foresight, the fundamental capacity for mental time travel. The evolution of forethought, the capacity to think ahead, is considered to have been a prime mover in human evolution. Planning is a fundamental property of intelligent behavior. It involves the use of logic and imagination to visualise not only a desired end result, but the steps necessary to achieve that result. An important aspect of planning is its relationship to forecasting. Forecasting aims to predict what the future will look like, while planning imagines what the future could look like. Planning according to established principles is a core part of many professional occupations, particularly in fields such as management and business. Once a plan has been developed it is possible to measure and assess progress, efficiency and effectiveness. As circumstances change, plans may need to be modifie ... [...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. Quality attributes Notable quality attributes include: * accessibility * accountability * accuracy * adaptability * administrability * affordability * agility * auditability * autonomy rl* availability * compatibility * composability rl* confidentiality * configurability * correctness * credibility * customizability * debuggability * degradability * determinability * demonstrability * dependability * deployability * discoverability rl* distributability * durability * effectiveness * efficiency * evolvability * extensibility * failure transparency * fault-tolerance * fidelity * flexibility * inspectability * instal ... [...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] |
