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Transient Modelling
Transient modelling is a way of looking at a process with the primary criterion of time, observing the pattern of changes in the subject being studied over time. Its obverse is Steady state, where you might know only the starting and ending figures but do not understand the process by which they were derived. Transient models will reveal the pattern of a process, which might be sinusoidal or another shape that will help to design a better system to manage that process. Transient models can be done on a spreadsheet with an ability to generate charts, or by any software that can handle data of inputs and outputs and generate some sort of a display. Transient modelling does not need a computer. It is a methodology that has worked for centuries, by observers noting patterns of change against time, analysing the result and proposing improved design solutions. A simple example is a garden water tank. This is being topped up by rainfall from the roof, but when the tank is full, the remai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Steady State
In systems theory, a system or a Process theory, process is in a steady state if the variables (called state variables) which define the behavior of the system or the process are unchanging in time. In continuous time, this means that for those properties ''p'' of the system, the partial derivative with respect to time is zero and remains so: : \frac = 0 \quad \text t. In discrete time, it means that the first difference of each property is zero and remains so: :p_t-p_=0 \quad \text t. The concept of a steady state has relevance in many fields, in particular thermodynamics, Steady state economy, economics, and engineering. If a system is in a steady state, then the recently observed behavior of the system will continue into the future. In stochastic systems, the probabilities that various states will be repeated will remain constant. See for example Linear difference equation#Conversion to homogeneous form for the derivation of the steady state. In many systems, a steady state i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sinusoidal
A sine wave, sinusoidal wave, or just sinusoid is a mathematical curve defined in terms of the '' sine'' trigonometric function, of which it is the graph. It is a type of continuous wave and also a smooth periodic function. It occurs often in mathematics, as well as in physics, engineering, signal processing and many other fields. Formulation Its most basic form as a function of time (''t'') is: y(t) = A\sin(2 \pi f t + \varphi) = A\sin(\omega t + \varphi) where: * ''A'', ''amplitude'', the peak deviation of the function from zero. * ''f'', ''ordinary frequency'', the ''number'' of oscillations (cycles) that occur each second of time. * ''ω'' = 2''f'', ''angular frequency'', the rate of change of the function argument in units of radians per second. * \varphi, ''phase'', specifies (in radians) where in its cycle the oscillation is at ''t'' = 0. When \varphi is non-zero, the entire waveform appears to be shifted in time by the amount ''φ''/''ω'' seconds. A negative value rep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spreadsheet
A spreadsheet is a computer application for computation, organization, analysis and storage of data in tabular form. Spreadsheets were developed as computerized analogs of paper accounting worksheets. The program operates on data entered in cells of a table. Each cell may contain either numeric or text data, or the results of formulas that automatically calculate and display a value based on the contents of other cells. The term ''spreadsheet'' may also refer to one such electronic document. Spreadsheet users can adjust any stored value and observe the effects on calculated values. This makes the spreadsheet useful for "what-if" analysis since many cases can be rapidly investigated without manual recalculation. Modern spreadsheet software can have multiple interacting sheets and can display data either as text and numerals or in graphical form. Besides performing basic arithmetic and mathematical functions, modern spreadsheets provide built-in functions for common financial a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water Tank
A water tank is a container for storing water. Water tanks are used to provide storage of water for use in many applications, drinking water, irrigation agriculture, fire suppression, agricultural farming, both for plants and livestock, chemical manufacturing, food preparation as well as many other uses. Water tank parameters include the general design of the tank, and choice of construction materials, linings. Various materials are used for making a water tank: plastics (polyethylene, polypropylene), fiberglass, concrete, stone, steel (welded or bolted, carbon, or stainless). Earthen pots, such as matki used in South Asia, can also be used for water storage. Water tanks are an efficient way to help developing countries to store clean water. History Throughout history, wood, ceramic and stone tanks have been used as water tanks. These containers were all naturally occurring and some man made and a few of these tanks are still in service. The Indus Valley civilization (30 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transient Climate Simulation
A transient climate simulation is a mode of running a global climate model (GCM) in which a period of time (typically 1850–2100) is simulated with continuously-varying concentrations of greenhouse gases so that the climate of the model represents a realistic mode of possible change in the real world. Related models This may be contrasted with an equilibrium climate simulation in which greenhouse gas concentrations are suddenly changed (typically from pre-industrial values to twice pre-industrial values) and the model allowed to come into equilibrium with the new forcing. History Early GCMs used "swamp" or "slab" ocean models for reasons of computational simplicity. Such models cannot simulate the heat take up that occurs in the real ocean and were thus unable to run transient simulations: instead, the response to equilibrium change was investigated. There are problems with this approach, which were well appreciated at the time: the deep ocean has a very long time constant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ice Core
An ice core is a core sample that is typically removed from an ice sheet or a high mountain glacier. Since the ice forms from the incremental buildup of annual layers of snow, lower layers are older than upper ones, and an ice core contains ice formed over a range of years. Cores are drilled with hand augers (for shallow holes) or powered drills; they can reach depths of over two miles (3.2 km), and contain ice up to 800,000 years old. The physical properties of the ice and of material trapped in it can be used to reconstruct the climate over the age range of the core. The proportions of different oxygen and hydrogen isotopes provide information about ancient temperatures, and the air trapped in tiny bubbles can be analysed to determine the level of atmospheric gases such as carbon dioxide. Since heat flow in a large ice sheet is very slow, the borehole temperature is another indicator of temperature in the past. These data can be combined to find the climate model ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Climate Change (general Concepts)
In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to Earth's climate. The current rise in global average temperature is more rapid than previous changes, and is primarily caused by humans burning fossil fuels. Fossil fuel use, deforestation, and some agricultural and industrial practices increase greenhouse gases, notably carbon dioxide and methane. Greenhouse gases absorb some of the heat that the Earth radiates after it warms from sunlight. Larger amounts of these gases trap more heat in Earth's lower atmosphere, causing global warming. Due to climate change, deserts are expanding, while heat waves and wildfires are becoming more common. Increased warming in the Arctic has contributed to melting permafrost, glacial retreat and sea ice loss. Higher temperatures are also causing more ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weather Forecasting
Weather forecasting is the application of science and technology forecasting, to predict the conditions of the Earth's atmosphere, atmosphere for a given location and time. People have attempted to predict the weather informally for millennia and formally since the 19th century. Weather forecasts are made by collecting quantitative data about the current state of the atmosphere, land, and ocean and using meteorology to project how the atmosphere will change at a given place. Once calculated manually based mainly upon changes in atmospheric pressure, barometric pressure, current weather conditions, and sky condition or cloud cover, weather forecasting now relies on numerical weather prediction, computer-based models that take many atmospheric factors into account. Human input is still required to pick the best possible forecast model to base the forecast upon, which involves pattern recognition skills, teleconnections, knowledge of model performance, and knowledge of model biases ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecosystem
An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the system through photosynthesis and is incorporated into plant tissue. By feeding on plants and on one another, animals play an important role in the movement of matter and energy through the system. They also influence the quantity of plant and microbial biomass present. By breaking down dead organic matter, decomposers release carbon back to the atmosphere and facilitate nutrient cycling by converting nutrients stored in dead biomass back to a form that can be readily used by plants and microbes. Ecosystems are controlled by external and internal factors. External factors such as climate, parent material which forms the soil and topography, control the overall structure of an ecosystem but are not themselves influenced by the ecosystem. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Floating Currency
In macroeconomics and economic policy, a floating exchange rate (also known as a fluctuating or flexible exchange rate) is a type of exchange rate regime in which a currency's value is allowed to fluctuate in response to foreign exchange market events. A currency that uses a floating exchange rate is known as a ''floating currency'', in contrast to a ''fixed currency'', the value of which is instead specified in terms of material goods, another currency, or a set of currencies (the idea of the last being to reduce currency fluctuations). In the modern world, most of the world's currencies are floating, and include the most widely traded currencies: the United States dollar, the euro, the Swiss franc, the Indian rupee, the pound sterling, the Japanese yen, and the Australian dollar. However, even with floating currencies, central banks often participate in markets to attempt to influence the value of floating exchange rates. The Canadian dollar most closely resembles a pure flo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Freeway
A controlled-access highway is a type of highway that has been designed for high-speed vehicular traffic, with all traffic flow—ingress and egress—regulated. Common English terms are freeway, motorway and expressway. Other similar terms include '' throughway'' and '' parkway''. Some of these may be limited-access highways, although this term can also refer to a class of highways with somewhat less isolation from other traffic. In countries following the Vienna convention, the motorway qualification implies that walking and parking are forbidden. A fully controlled-access highway provides an unhindered flow of traffic, with no traffic signals, intersections or property access. They are free of any at-grade crossings with other roads, railways, or pedestrian paths, which are instead carried by overpasses and underpasses. Entrances and exits to the highway are provided at interchanges by slip roads (ramps), which allow for speed changes between the highway and arter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bank Statement
A bank statement is an official summary of financial transactions occurring within a given period for each bank account held by a person or business with a financial institution. Such statements are prepared by the financial institution, are numbered and indicate the period covered by the statement, and may contain other relevant information for the account type, such as how much is payable by a certain date. The start date of the statement period is usually the day after the end of the previous statement period. Once produced and delivered to the customer, details on the statement are not normally alterable; any error found would normally be corrected on a future statement, usually with some correspondence explaining the reason for the adjustment. Bank statements are commonly used by the customer to monitor cash flow, check for possible fraudulent transactions, and perform bank reconciliations. Historically they have been printed on one or more pieces of paper, and either mail ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
