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Operational Availability
Operational availability in systems engineering is a measurement of how long a system has been available to use when compared with how long it should have been available to be used. Definition Operational availability is a management concept that evaluates the following. * Diagnostic down time * Criticality * Fault isolation down time * Logistics delay down time * Corrective maintenance down time Any failed item that is not corrected will induce operational failure. A_o is used to evaluate that risk. Operational failure is unacceptable in any situation where the following can occur. * Capital equipment loss * Injury or loss of life * Sustained failure to accomplish mission In military acquisition, operational availability is used as one of the Key Performance Parameters in requirements documents, to form the basis for decision support analyses. History Aircraft systems, ship systems, missile systems, and space systems have a large number of failure modes that must be addressed ... [...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 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. Issues such as requirements engineering, reliability, logistics, coordination of different teams, testing and evaluation, maintainability and many other 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 and human-centered disciplines such as industrial engineeri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Key Performance Parameters
Key Performance Parameters (KPPs) specify what the critical performance goals are in a United States Department of Defense (DoD) acquisition under the JCIDS process. The JCIDS intent for KPPs is to have a few measures stated where the acquisition product either meets the stated performance measure or else the program will be considered a failure per instructions CJCSI 3170.01H – Joint Capabilities Integration and Development System. The mandates require 3 to 8 KPPs be specified for a United States Department of Defense major acquisition, known as Acquisition Category 1 or ACAT-I. The term is defined as "Performance attributes of a system considered critical to the development of an effective military capability. A KPP normally has a threshold representing the minimum acceptable value achievable at low-to-moderate risk, and an objective, representing the desired operational goal but at higher risk in cost, schedule, and performance. KPPs are contained in the Capability Developm ... [...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 through three mechanisms. * Reduce labor-intensive diagnostic evaluation * Eliminate diagnostic testing down-time * Provide notification to management for degraded operation This is a prerequisite for Condition-based maintenance. Active redundancy can be integrated with fault reporting to reduce down time to a few minutes per year. * Passive redundancy * Active redundancy 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. This 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 th ... [...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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reliability Block Diagram
A reliability block diagram (RBD) is a diagrammatic method for showing how component reliability contributes to the success or failure of a redundant. RBD is also known as a dependence diagram (DD). An RBD is drawn as a series of blocks connected in parallel or series configuration. Parallel blocks indicate redundant subsystems or components that contribute to a lower failure rate. Each block represents a component of the system with a failure rate. RBDs will indicate the type of redundancy in the parallel path. For example, a group of parallel blocks could require two out of three components to succeed for the system to succeed. By contrast, any failure along a series path causes the entire series path to fail. An RBD may be drawn using switches in place of blocks, where a closed switch represents a working component and an open switch represents a failed component. If a path may be found through the network of switches from beginning to end, the system still works. An RB ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Active Redundancy
Active redundancy is a design concept that increases operational availability and that reduces operating cost by automating most critical maintenance actions. This concept is related to condition-based maintenance and fault reporting. History The initial requirement began with military combat systems during World War I. The approach used for survivability was to install thick armor plate to resist gun fire and install multiple guns. This became unaffordable and impractical during the Cold War when aircraft and missile systems became common. The new approach was to build distributed systems that continue to work when components are damaged. This depends upon very crude forms of artificial intelligence that perform reconfiguration by obeying specific rules. An example of this approach is the AN/UYK-43 computer. Formal design philosophies involving active redundancy are required for critical systems where corrective labor is undesirable or impractical to correct failure during ... [...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] |
Downtime
The term downtime is used to refer to periods when a system is unavailable. The unavailability is the proportion of a time-span that a system is unavailable or offline. This is usually a result of the system failing to function because of an unplanned event, or because of routine maintenance (a planned event). The term is commonly applied to networks and servers. The common reasons for unplanned outages are system failures (such as a crash) or communications failures (commonly known as network outage). The term is also commonly applied in industrial environments in relation to failures in industrial production equipment. Some facilities measure the downtime incurred during a work shift, or during a 12- or 24-hour period. Another common practice is to identify each downtime event as having an operational, electrical or mechanical origin. The opposite of downtime is uptime. Types Industry standards for the term "Outage Duration" or "Maintenance Duration" can have different p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reliability Block Diagram
A reliability block diagram (RBD) is a diagrammatic method for showing how component reliability contributes to the success or failure of a redundant. RBD is also known as a dependence diagram (DD). An RBD is drawn as a series of blocks connected in parallel or series configuration. Parallel blocks indicate redundant subsystems or components that contribute to a lower failure rate. Each block represents a component of the system with a failure rate. RBDs will indicate the type of redundancy in the parallel path. For example, a group of parallel blocks could require two out of three components to succeed for the system to succeed. By contrast, any failure along a series path causes the entire series path to fail. An RBD may be drawn using switches in place of blocks, where a closed switch represents a working component and an open switch represents a failed component. If a path may be found through the network of switches from beginning to end, the system still works. An RB ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maintenance
Maintenance may refer to: Biological science * Maintenance of an organism * Maintenance respiration Non-technical maintenance * Alimony, also called ''maintenance'' in British English * Champerty and maintenance, two related legal doctrines * Child support, also commonly called "child maintenance" * Feudal maintenance, system of funding armies Technical maintenance * Maintenance (technical) * Aircraft maintenance * Bicycle maintenance * Bus maintenance * Car maintenance * Train maintenance * Property maintenance * Railroad track maintenance * Software maintenance Some kinds of technical maintenance * Condition-based maintenance * Corrective maintenance * Planned 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 install ... * Predictive maintenance * Preven ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Engineering Concepts
Engineering is the use of 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 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 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 or operate the same with full cognizance of their design; or to forecast their behavior under spec ... [...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 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 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 prediction, prevention and mana ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
