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326 results about "Laws of thermodynamics" patented technology

The three laws of thermodynamics define physical quantities (temperature, energy, and entropy) that characterize thermodynamic systems at thermal equilibrium. The laws describe how these quantities behave under various circumstances, and preclude the possibility of certain phenomena (such as perpetual motion).

Symmetric obtaining method for coefficient of active power transmission from nodes to branches in power network

The invention belongs to the field of electric power engineering, and provides a symmetric obtaining method for a coefficient of active power transmission from nodes to branches in a power network. According to the method, a linear function relationship between branch active power and node voltage phase angles is established according to known alternating current power network parameters and alternating current power network running characteristics, a symmetric linear function relationship between the node voltage phase angles and node injected active power is established according to the linear function relationship and the node injected active power, a symmetric linear function relationship between the branch active power and the node injected active power is established according to the linear function relationship and the known symmetric linear function relationship, and the coefficient of the active power transmission from the nodes to the branches is obtained according to the symmetric linear function relationship and the function relationship between the branch active power and the coefficient of the active power transmission from the nodes to the branches. The problems that existing obtaining methods for the coefficient of the active power transmission from the nodes to the branches go against a physical symmetry rule and a circuital law, and cannot reflect the characteristics of the active power transmission from the nodes to the branches truly are solved.
Owner:SHENZHEN UNIV

Method for evaluating fatigue life of aged reinforced concrete bridge

ActiveCN105825030AThe prediction method is reasonableGeometric CADForecastingStress concentrationCrazing
The invention discloses a method for evaluating the fatigue life of an aged reinforced concrete bridge. The method comprises the following steps of obtaining initial corrosion time of reinforcement in concrete based on the second diffusion law of Fick, and considering the influence of concrete cracking due to corrosion expansion in a corrosion rate model; adopting a small crack growth and near threshold growth analysis and determining relevant parameters of fatigue crack propagation rate of materials by developing a fatigue crack propagation test of reinforced concrete materials; performing a corrosion fatigue test or finite element analysis on corroded reinforcement to obtain stress concentration factors at different corrosion levels, and integrating into a stress intensity factor model to obtain the fatigue crack propagation rate of the reinforcement under the influence of corrosion; comparing the magnitude of a corrosion pit growth rate and the fatigue crack propagation rate and gradually converting into a single growth analysis on fatigue cracks of the reinforcement; meanwhile, combining with vehicle load observing information to realize life evaluation of a bridge at different service stages. The prediction method disclosed by the invention is reasonable and high in popularization, and can provide technical support for evaluating the life of the concrete bridges.
Owner:CHANGSHA UNIVERSITY OF SCIENCE AND TECHNOLOGY

Brazilian split method for measuring elastic parameter of rock under extension condition

InactiveCN102183410AGain tensile strengthGet elastic parametersMaterial strength using tensile/compressive forcesCircular discStress conditions
The invention discloses a Brazilian split method for measuring an elastic parameter of a rock under an extension condition, which comprises the steps of: A. horizontally putting a machined disc-shaped sample between the load bearing plates of a press machine by using a Brazilian disc split method, placing a hard steel wire respectively between the upper load bearing plate and the sample and between the lower load bearing plate and the sample, arranging a filler strip perpendicular to the symmetrical surfaces of the sample, and applying pressure on the upper load bearing plate and the lower load bearing plate to make the sample generate tension perpendicular to the action directions of an upper load and a lower load; B. carrying out analysis by using the Hooke's law in classical elasticity mechanics by combining specific conditions of the Brazilian split method; C. analyzing the stress condition of the rock and the measurement principle in the Brazilian disc split method; and D. obtaining the strain in the stress direction according to the Hooke's law from the stress condition sigma3=0, measuring epsilon1 and epsilon2, obtaining the elastic parameter of the rock sample, and arranging a strain gauge in the center position of the rock sample for measurement of epsilon1 and epsilon2. The method has the advantages of easiness for operation and use, clear principle, low material consumption, and the like. The method is suitable for wide popularization and application.
Owner:INST OF ROCK AND SOIL MECHANICS - CHINESE ACAD OF SCI

Dynamic correction method for reliability assessment of large-sized oil-immersed power transformer

The invention discloses a dynamic correction method for reliability assessment of a large-sized oil-immersed power transformer; a transformer oil-paper insulating system is used as an assessment object, and two processes are involved; in the first process, with hotspot temperature calculation as the core, an HST-based (hotspot temperature) transformer aging fault model is established in conjunction with Weibull distribution and Arrhenius reaction law, winding HST is acquired by calculating, and fault rate gamma of the transformer oil-paper insulating system is solved; in the second process, with gray target correction analysis via dissolved gas in oil as the core, a relationship between transformer health state and its predicted life is established via grey theory, equivalent HST value is obtained, dynamic correction is provided for the basic model in the first process, and it is ensured that the assessment value is capable of well tracing and reflecting actual reliability level of the transformer. By using the method, it is possible to effectively solve the problems that, for instance, a transformer reliability analysis model has low accuracy and is difficult to popularize and apply.
Owner:SOUTH CHINA UNIV OF TECH

Photovoltaic intelligent community electric automobile and controllable load two-stage optimization scheduling method

The invention discloses a photovoltaic intelligent community electric automobile and controllable load two-stage optimization scheduling method. A controllable load output model is established based on residential area, controllable load use characteristics and laws of thermodynamics, an electric automobile charging model is established based on electric automobile user driving characteristics, and a photovoltaic probability model is established based on the condition that photovoltaic output forecast deviations meet normal distribution; in day-ahead scheduling, time-of-use electricity price is set with profit maximization of an operator obtained after orderly charging of electric automobiles being as a target, and the electric automobiles are guided to be charged orderly through the time-of-use electricity price to reduce system valley-peak difference; taking consideration of influence of photovoltaic prediction and temperature prediction deviation on intelligent community electric automobile and controllable load co-scheduling, supply and demand unbalance due to day-ahead predication is corrected by introducing real-time scheduling; and in real-time scheduling, with the time-of-use electricity price set in day-ahead scheduling being as a basis, a day-ahead charging scheme of the electric automobiles is optimized to reduce real-time scheduling cost and stabilize load fluctuation. The method comprises day-ahead scheduling and real-time scheduling two-stage optimization.
Owner:SOUTHWEST JIAOTONG UNIV
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