Event Tree
An event tree is an inductive analytical diagram in which an event is analyzed using Boolean logic to examine a chronological series of subsequent events or consequences. For example, event tree analysis is a major component of nuclear reactor safety engineering.Wang, John '' et al.'' (2000). An event tree displays sequence progression, sequence end states and sequence-specific dependencies across time. Analytical tool Event tree analysis is a logical evaluative process which works by tracing forward in time or forwards through a causal chain to model risk. It does not require the premise of a known hazard. An event tree is an inductive investigatory process. In contrast, the Fault tree analysis (FTA) evaluates risk by tracing backwards in time or backwards through a cause chain. The analysis takes as a premise a given hazard. FTA is a deductive investigatory process. Applications An event tree may start from a specific initiator such as loss of critical supply, or component f ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Boolean Logic
In mathematics and mathematical logic, Boolean algebra is a branch of algebra. It differs from elementary algebra in two ways. First, the values of the variable (mathematics), variables are the truth values ''true'' and ''false'', usually denoted 1 and 0, whereas in elementary algebra the values of the variables are numbers. Second, Boolean algebra uses Logical connective, logical operators such as Logical conjunction, conjunction (''and'') denoted as ∧, Logical disjunction, disjunction (''or'') denoted as ∨, and the negation (''not'') denoted as ¬. Elementary algebra, on the other hand, uses arithmetic operators such as addition, multiplication, subtraction and division. So Boolean algebra is a formal way of describing logical operations, in the same way that elementary algebra describes numerical operations. Boolean algebra was introduced by George Boole in his first book ''The Mathematical Analysis of Logic'' (1847), and set forth more fully in his ''The Laws of Thought, ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Event Tree Analysis
Event tree analysis (ETA) is a forward, top-down, logical modeling technique for both success and failure that explores responses through a single initiating event and lays a path for assessing probabilities of the outcomes and overall system analysis. This analysis technique is used to analyze the effects of functioning or failed systems given that an event has occurred.Wang, John '' et al.'' (2000). ETA is a powerful tool that will identify all consequences of a system that have a probability of occurring after an initiating event that can be applied to a wide range of systems including: nuclear power plants, spacecraft, and chemical plants. This technique may be applied to a system early in the design process to identify potential issues that may arise, rather than correcting the issues after they occur. With this forward logic process, use of ETA as a tool in risk assessment can help to prevent negative outcomes from occurring, by providing a risk assessor with the probabili ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Fault Tree Analysis
Fault tree analysis (FTA) is a type of failure analysis in which an undesired state of a system is examined. This analysis method is mainly used in safety engineering and reliability engineering to understand how systems can fail, to identify the best ways to reduce risk and to determine (or get a feeling for) event rates of a safety accident or a particular system level (functional) failure. FTA is used in the aerospace, nuclear power, chemical and process, pharmaceutical, petrochemical and other high-hazard industries; but is also used in fields as diverse as risk factor identification relating to social service system failure. FTA is also used in software engineering for debugging purposes and is closely related to cause-elimination technique used to detect bugs. In aerospace, the more general term "system failure condition" is used for the "undesired state" / top event of the fault tree. These conditions are classified by the severity of their effects. The most severe condi ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Timeline Of The Fukushima I Nuclear Accidents
Fukushima Daiichi is a multi-Nuclear reactor technology, reactor Nuclear power plant, nuclear power site in the Fukushima Prefecture of Japan. Fukushima Daiichi nuclear disaster, A nuclear disaster occurred there after a Moment magnitude scale, 9.0 magnitude 2011 Tōhoku earthquake and tsunami, earthquake and subsequent tsunami on 11 March 2011. The earthquake triggered a scram shut down of the three active reactors, and the ensuing tsunami crippled the site, stopped the backup diesel generators, and caused a station power outage, blackout. The subsequent Loss-of-coolant accident, lack of cooling led to explosions and nuclear meltdown, meltdowns, with problems at three of the six reactors and in one of the six Spent nuclear fuel, spent-fuel pools. Times are given in Japan Standard Time (JST), unless noted, which is UTC+09:00, UTC plus nine hours. March 2011 Monday, 7 March Tokyo Electric Power Company (TEPCO) submits a report to Japan's nuclear safety agency which predicts t ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Northeast Blackout Of 2003
The Northeast blackout of 2003 was a widespread power outage throughout parts of the Northeastern and Midwestern United States, and most parts of the Canadian province of Ontario on Thursday, August 14, 2003, beginning just after 4:10 p.m. EDT. Most places restored power by midnight (within 7 hours), some as early as 6 p.m. on August 14 (within 2 hours), while the New York City Subway resumed limited services around 8 p.m. Full power was restored to New York City and Toronto on August 16. At the time, it was the world's second most widespread blackout in history, after the 1999 Southern Brazil blackout. The outage, which was much more widespread than the Northeast blackout of 1965, affected an estimated 10 million people in southern and central Ontario, and 45 million people in eight U.S. states. The blackout's proximate cause was a software bug in the alarm system at the control room of FirstEnergy, an Akron, Ohio–based company, which rendered operators una ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Probabilistic Safety Assessment
Probabilistic risk assessment (PRA) is a systematic and comprehensive methodology to evaluate risks associated with a complex engineered technological entity (such as an airliner or a nuclear power plant) or the effects of stressors on the environment (probabilistic environmental risk assessment, or PERA). Risk in a PRA is defined as a feasible detrimental outcome of an activity or action. In a PRA, risk is characterized by two quantities: #the magnitude (severity) of the possible adverse consequence(s), and #the likelihood (probability) of occurrence of each consequence. Consequences are expressed numerically (e.g., the number of people potentially hurt or killed) and their likelihoods of occurrence are expressed as probabilities or frequencies (i.e., the number of occurrences or the probability of occurrence per unit time). The total risk is the expected loss: the sum of the products of the consequences multiplied by their probabilities. The spectrum of risks across classes ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Event Structure
In mathematics and computer science, an event structure represents a set of events, some of which can only be performed after another (there is a ''dependency'' between the events) and some of which might not be performed together (there is a ''conflict'' between the events). Formal definition An event structure (E,\leq,\#) consists of * a set E of events * a partial order relation on E called causal dependency, * an irreflexive symmetric relation \# called incompatibility (or conflict) such that * ''finite causes'': for every event e \in E, the set = \ of predecessors of e in E is finite * ''hereditary conflict'': for every events d,e,f \in E, if d \leq e and d \# f then e \# f. See also * Binary relation * Mathematical structure In mathematics, a structure is a set endowed with some additional features on the set (e.g. an operation, relation, metric, or topology). Often, the additional features are attached or related to the set, so as to provide it with some additional ... ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Root Cause Analysis
In science Science is a systematic endeavor that builds and organizes knowledge in the form of testable explanations and predictions about the universe. Science may be as old as the human species, and some of the earliest archeological evidence for ... and engineering, root cause analysis (RCA) is a method of problem solving used for identifying the root causes of faults or problems. It is widely used in IT operations, manufacturing, telecommunications, Process control, industrial process control, accident analysis (e.g., in aviation, rail transport, or nuclear plants), medicine (for medical diagnosis), healthcare industry (e.g., for epidemiology), etc. Root cause analysis is a form of deductive inference since it requires an understanding of the underlying causal mechanisms of the potential root causes and the problem. RCA can be decomposed into four steps: * Identify and describe the problem clearly * Establish a timeline from the normal situation until the problem ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Ishikawa Diagram
Ishikawa diagrams (also called fishbone diagrams, herringbone diagrams, cause-and-effect diagrams) are causal diagrams created by Kaoru Ishikawa that show the potential causes of a specific event. Common uses of the Ishikawa diagram are product design and quality defect prevention to identify potential factors causing an overall effect. Each cause or reason for imperfection is a source of variation. Causes are usually grouped into major categories to identify and classify these sources of variation. Overview The ''defect'' is shown as the fish's head, facing to the right, with the ''causes'' extending to the left as fishbones; the ribs branch off the backbone for major causes, with sub-branches for root-causes, to as many levels as required. Ishikawa diagrams were popularized in the 1960s by Kaoru Ishikawa, who pioneered quality management processes in the Kawasaki shipyards, and in the process became one of the founding fathers of modern management. The basic concept was fi ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Failure Mode And Effects Analysis
Failure mode and effects analysis (FMEA; often written with "failure modes" in plural) is the process of reviewing as many components, assemblies, and subsystems as possible to identify potential failure modes in a system and their causes and effects. For each component, the failure modes and their resulting effects on the rest of the system are recorded in a specific FMEA worksheet. There are numerous variations of such worksheets. An FMEA can be a qualitative analysis, but may be put on a quantitative basis when mathematical failure rate models are combined with a statistical failure mode ratio database. It was one of the first highly structured, systematic techniques for failure analysis. It was developed by reliability engineers in the late 1950s to study problems that might arise from malfunctions of military systems. An FMEA is often the first step of a system reliability study. A few different types of FMEA analyses exist, such as: * Functional * Design * Process Sometime ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Quality
Quality may refer to: Concepts *Quality (business), the ''non-inferiority'' or ''superiority'' of something *Quality (philosophy), an attribute or a property *Quality (physics), in response theory *Energy quality, used in various science disciplines *Logical quality, philosophical categorization of statements *Service quality, comparison of expectations with performance in a service *Vapor quality, in thermodynamics, the ratio of mass of vapor to that of vapor and liquid *Data quality, refers to the condition of a set of values of qualitative or quantitative variables Practices *Quality assurance (QA) *Quality control (QC) Places *Quality, Kentucky, an unincorporated community Brands and enterprises *Quality Comics, an American comic book publisher between 1939 and 1956 *Quality Communications, a comic book publisher started in 1982 *Quality Records, a Canadian entertainment company Music * ''Quality'' (CDQ album), 2016 * ''Quality'' (Talib Kweli album), 2002 *"Quality", a song ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |