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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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 by 1 and 0, whereas in elementary algebra the values of the variables are numbers. Second, Boolean algebra uses logical operators such as Logical conjunction, conjunction (''and'') denoted as , disjunction (''or'') denoted as , and negation (''not'') denoted as . Elementary algebra, on the other hand, uses arithmetic operators such as addition, multiplication, subtraction, and division. Boolean algebra is therefore 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 ''An Investigation of the Laws of Thought'' (1854). According to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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] |
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 conditi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Timeline Of The Fukushima I Nuclear Accidents
Fukushima Daiichi is 1 of 2 multi- reactor nuclear power sites in the Fukushima Prefecture of Japan. A nuclear disaster occurred there after a 9.0 magnitude 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 blackout. The subsequent lack of cooling led to explosions and meltdowns, with problems at three of the six reactors and in one of the six spent-fuel pools. Times are given in Japan Standard Time (JST), unless noted, which is 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 the possibility of a tsunami up to 10.2 metres high at the Fukushima Daiichi nuclear plant in the event of an earthquake similar to the magnitude 7.2 earthquake with accompanying tsunami that devastated the area in 1896. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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] |
Event Structure
Event may refer to: Gatherings of people * Ceremony, an event of ritual significance, performed on a special occasion * Convention (meeting), a gathering of individuals engaged in some common interest * Event management, the organization of events * Festival, an event that celebrates some unique aspect of a community * Happening, a type of artistic performance * Media event, an event created for publicity * Party, a social, recreational or corporate events held * Sporting event, at which athletic competition takes place * Virtual event, a gathering of individuals within a virtual environment Science, technology, and mathematics * Event (computing), a software message indicating that something has happened, such as a keystroke or mouse click * Event (philosophy), an object in time, or an instantiation of a property in an object * Event (probability theory), a set of outcomes to which a probability is assigned * Event (relativity), a point in space at an instant in time, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Root Cause Analysis
In science 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, industrial process control, accident analysis (e.g., in aviation, rail transport, or nuclear plants), medical diagnosis, the healthcare industry (e.g., for epidemiology), etc. Root cause analysis is a form of inductive inference (first create a theory, or ''root'', based on empirical evidence, or ''causes'') and deductive inference (test the theory, i.e., the underlying causal mechanisms, with empirical data). RCA can be decomposed into four steps: # Identify and describe the problem clearly # Establish a timeline from the normal situation until the problem occurrence # Distinguish between the root cause and other causal factors (e.g., via event correlation) # Establish a causal graph between the root cause and the problem. RCA generally serves as input to a r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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'', or the problem to be solved, 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 manag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Failure Mode And Effects Analysis
Failure is the social concept of not meeting a desirable or intended Goal, objective, and is usually viewed as the opposite of success. The criteria for failure depends on context, and may be relative to a particular observer or belief system. One person might consider a failure what another person considers a success, particularly in cases of direct competition or a zero-sum game. Similarly, the degree of success or failure in a situation may be differently viewed by distinct observers or participants, such that a situation that one considers to be a failure, another might consider to be a success, a qualified success or a neutral situation. It may also be difficult or impossible to ascertain whether a situation meets criteria for failure or success due to ambiguous or ill-defined definition of those criteria. Finding useful and effective criteria or heuristics to judge the success or failure of a situation may itself be a significant task. Sociology Cultural historian Sco ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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) *Quality management system (QMS) *Quality management, Quality Management (QM) Places *Quality, Kentucky, an unincorporated community Brands and enterprises *Quality Comics, an American comic book publisher between 1939 and 1956 *Quality Communications, a British comic book publisher between 1982 and 2008 *Quality Records, a Canadian entertainment company Musi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
