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1.
在分析地震条件下管线功能函数及极限状态方程基础上,对城市供水管单元体进行震害预测。以供水管网系统作为边权的有向网络图,通过基于神经网络的Monte Carlo方法,模拟各管线运行状态及其破坏状态。结合图论理论,分析供水管网的管线连通可靠性。  相似文献   

2.
In order to ensure the function of building in the earthquake, reduce economic losses and facilitate post-disaster relief, it is necessary to accurately evaluate the seismic performance of pipeline system on the structure under seismic excitation. Considering this practical need, seismic response calculation methods of piping systems on structures were systematically studied. Firstly, theoretical derivation was performed based on the pseudo-excitation method for seismic response of pipeline system. It is found that the formula in previous studies has obvious defect: the accurate relative displacement values of degree of freedom near the supports can not be obtained in the formula. Thereby, the theoretical basis for derivation was mended to correct the defect, and the uniform combination expressions available for pipeline's seismic response calculation which is in the form of ground response spectrum or floor response spectrum were presented. Moreover, the simplified formulas and calculation method of correlation coefficients in the obtained expressions were put forward according to the assumption of white noise earthquake excitation. Finally, case studies were adopted to verify the proposed method's effectiveness and applicability in the seismic response calculation of pipeline system.  相似文献   

3.
Branch -like pipeline is a common structure in gas transmission pipeline. In the light of the constituent properties of natural gas branch - like pipeline system, the system can be divided into fundamental constituent units. This paper presents a realistic unsteady flow model consisting of simple models of pipeline units and connecting conditions, boundary conditions and initial condition associated with units by using system analysis method. The solutions in wide sense are obtained by theory of functional analysis and operator series method, Such a method has the properties of both analytical solution and numerical solution methods. When the divided pipeline unit is larger, an intuitive approximate analytical solution may be obtained; while the one is smaller, a more accurate numerical solution may be acquired. Based on this, a general computer program has been developed for this model and solutions have been used successfully in a local natural gas transmission network in Sichuan. It is proved that the model and algorithm proposed in this paper are of the advantages of convenient calculation, high precision, time saving and wide application range by way of analysis and application.  相似文献   

4.
Equivalent linear system method is the main method of nonlinear structural system random response analysis. While it would generate big error when the results of equivalent linear system method are used to analyze the structural dynamic reliability. Through minimum mean square error principle, general nonlinear system was converted to equivalent Duffing nonlinear system, based on which the structural dynamic reliability was analyzed. The accurate steady state analytic solution of Duffing nonlinear system can be worked out by FPK equation, so it is not only convenient but also accurate to analyze structural dynamic reliability by using the equivalent nonlinear system method. It is also shown that the analysis results of equivalent nonlinear system method presented here is reliable and the calculation accuracy is higher than equivalent linear system method apparently through the example analysis.  相似文献   

5.
Component reliability parameters are of uncertainty and are affected by the component type, operation time, and weather conditions. So do the reliability indices of bulk power systems. The calculation of its probability distributions and its alteration law affected by parameters uncertainty are researched to provide practical engineering reference with exploring the impact of the parameter uncertainty on reliability assessment. The point estimate method is firstly proposed based on the two-loop Monte-Carlo simulation, and then the improved Monte-Carlo simulation is presented to enhance the calculation efficiency further. Moreover, their theories, merits and faults are explained in detail. It can be seen from the evaluation results for the RBTS power systems that the accuracy of the three methods are similar but the improved Monte-Carlo simulation has the highest efficiency, followed by the point estimate method. The IEEE-RTS 79 power system is evaluated by using the improved Monte-Carlo simulation, and the results verify its validity.  相似文献   

6.
This paper sums up the current situation of water supply and drainage designs of residential building. In accordance with the owner's demands, the problems related to the installation of water meter and water heater, the layout of pipeline, selection of pipe material and engineering measures are discussed respectively. It also points out some problems existed and inquires into the water system design for residential houses in the future.  相似文献   

7.
RELAP5 Analysis of Passive Emergency Core Cooling System Tests   总被引：1，自引：0，他引：1  
One of the apparent characteristic of advanced PWR is the high reliability of passive safety system .It is important to assess the operation behavior of such system and the ability of system analysis code as RELAP5.One principal test facility, passive emergency core cooling system experiments is carried out. The RELAP5/Mod3.2 is used to simulated the experiments in this paper. The simulation capability of RELAP5/Mod3.2 in passive emergency core cooling system is assessed through the comparison between the experimental results and calculation results.  相似文献   

8.
In order to optimize design and operation, it is necessary to calculate accurately hydraulic characteristics large central air-conditioning systems. Simplified Model can not be applied to hydraulic calculation of large pipe network topological structure for its large calculation error. Taking into account the regulating characteristics of terminal branch temperature regulating valve, a direct-return chilled water system is studied, an accurate mathematical model of pipe network hydraulic characteristics has been established and a computer logic algorithm with virtual flow has been given. A direct-return pipe network with ten AHU branches is used as simulation calculation object, the pipe network supply-return water pressure difference is calculated, and also the temperature regulating valve opening and actual flow of each branch are calculated in the condition of different supply-return water pressure difference. The calculated results accord with the natural characteristics of high pressure difference unbalanced for direct-return pipe network. The calculation method can ensure calculation convergence.  相似文献   

9.
An optimal active power adjustment model is deve in this paper for hybrid AC/DC systems after outage contingencies. The objective of the model is to minimize the rejection of load when some elements are out of service, with adjustment strategy approaching practical system operation. A large number of outage contingencies are simulated when the Monte-Carlo Method is emyloyed to evaluate the system reliability, requiring fast calculation of each simulation. The model and computer method proposed in this paper satisfy such a requirment because of the application of concentric relaxation, recursive branch constraint treatment in linear programming and a direct method for B-1 matrix modification. This paper is concerned with the simplified steady state conditions of the system based on DC load-flow, which implies the reliability indices calculated are the measures about static loss of load. The results for a 14-bus hybrid AC/DC system are given.  相似文献   

10.
Various defects and cracks may be produced in the welding process in natural gas pipeline.Under variable pressure of natural gas,the cracks will be propagated it may lead to break and invalidity.The effect of internal surface cracks are more serious.It has been researched that the propagation along radial direction of internel surface cracks in the natural gas pipeline.The fatig life of pipeline has been calculated.On the other hand,considering the size of cracks, pressure of gas and character of material are random variable,and by using reliability method,the fatig reliable life of pipeline has been determined.This method has some practical value in design, working and overhaul of pipeline.  相似文献   

11.
The authors definitely make out the concept of loop main pipeline, supplying main pipeline and ramiform branch line, as well as the order of their hydraulic calculation. Then they puts forward the principia of how to study out the direction of loop main pipeline and presents the method of making flux initial distribution. The matrix of loop main pipeline hydraulic square dispersion is set up. The node referenced pressure is defined and the equation of how to calculate it is deduced. A software is developed to calculate the loop main pipeline hydraulic square dispersion. The method of calculating ramiform branch margin impetus is given.  相似文献   

12.
The purpose of a power system is to deliver the power the customers require in real time, on demand, within acceptable voltage and frequency limit, and in a reliable and economic manner. Using NLPNN (New Linear Programming Neural Network) model, the behavior analysis of power system under fault conditions is carried through. The stability and convergence theorems are set up to obtain the resolution for the problem of the load curtailment strategy. A new way is open up to evaluate the reliability of power systems and the great progress in calculation analysis model is achieved. The new calculation technique and theory foundation of reliability evaluation are supplied.  相似文献   

13.
It is helpful for energy efftciency to use distributed pumps instead of valves to regulate hydraulic balance in a district heating system (DHS). A new scheme of distributed pump-system is presented based on performance comparison of hydraulic regime and power saving of single-heat-source dendritic pipeline networks with regulating valves and/or distributed pumps. Supposing that the new scheme was employed in multi-sources looped-pipe network, theoretical analysis and case study were carried out to evaluate off-design performances including hydraulic self-regulation, supply water temperature stability and power-saving potential. The results indicated that the proposed scheme would contribute to minimizing power consumption, retarding water temperature change, and would be convenient to adjust the quality and quantity independently in the looped-pipe heat supply networks.  相似文献   

14.
The vertical U-tube ground-coupled heat pump system provides cold and heat for the controlling of indoor environment. Under the air-conditioning condition, the vertical U-tube ground-coupled heat pump system with heat recovery can provide domestic hot water. The influence of supplying domestic hot water on the heat transfer performance of ground heat exchangers is different under different operating modes in summer and winter. Through a project design of ground-source heat pump system, the influence of supplying domestic hot water under heat storage mode on the heat transfer performance of ground heat exchangers in summer and winter is respectively analyzed. The dynamic performance of heat exchangers under different working conditions is analyzed, and through numerical calculation, the heat transfer performance parameters of ground heat exchangers under different operating modes are obtained. From the calculation results, the adjusting methods based on the load characteristics of this project represent.  相似文献   

15.
As information base of city water supply pipeline net inspection system, this paper gives the data composition of the system, discusses the basic composition and its setup way, as well as the application of GIS in this information system. It gives the connection function and analyzes the data gathering and data interface. Then, the proposition of system application and some key technology for development of this system are presented.  相似文献   

16.
The buried box girders in the mountain city sewage pipeline system would be turned into simple-supported girders because of the removal of the foundation caused by landslide.This change of supporting would result in the failure risk of pipeline structure.The static properties of the buried box girders with small depth-to-span ratio in simple-supported condition are experimentally analyzed.The failure pattern,shear behavior and shear lag effect of the buried box girders in simple-supported condition are studied.The shortages in the present design codes for the calculation of shear capacities of the box girders are also discussed.It is shown that under the vertical uniformly distributed load,the crack distribution of the box girders is uniform,and no major critical diagonal crack is formed,and the box girders lose the bearing capacity in the form of concrete diagonal rod crushing.As the main shear-bearing components,the stirrups devote much to shear capacity of the box girder after concrete cracking.The strains of the longitudinal rebars are affected by those factors such as the redistribution of internal force and cracks,so only few areas of the box girders show the shear lag effect.The change of supporting form leads to the premature cracking of concrete and affects the serviceability of the sewage pipeline.  相似文献   

17.
When the water supply network suffered earthquake damages, pipeline leaks and bursts may occur. In the period in post-earthquake emergency rescue and repair, the network is supplying water with additional outflow of damages (leaks and breaks), which result in pressure deficient. According to the frictional head loss along the break pipeline, a model with additional emitter at the endpoint of the disconnect pipeline was proposed to simulate the break, which simplifies the modeling of breaks. The pressure-dependent demand relationship was adopted in the process of pressure-deficient hydraulic simulation to avoid node negative pressure. Meanwhile a backtracking and line search procedure was utilized to control the iteration step of pipeline network nonlinear equations, which ensure the global convergence of the hydraulic simulation. The effectiveness of the proposed method was verified by a case study.  相似文献   

18.
Based on L.A.Zadeh's idea of fuzzy probability operation in his language probability which space is fuzzy probability,the concrete algorithm of the second kind fuzzy reliability of engineering structure/system is researched.The calculating equation of the fuzzy probabiliy of the second kind fuzzy reliability is given out by using the extension principle for fuzzy sets.The fuzzy set decompose theorem,which satesfies the closed probability operation,is given out and proved.The method calculating fuzzy reliability of that structure/system is studied,where the resistance and load effect of the structure/system have probability.The analysis indicates that the calculation of the second kind fuzzy reliability for a structure/system can be transformed into a series of solving optimum programming.The result of the example indicates the rationality of above algorithm.  相似文献   

19.
Aiming at the central mechanical circulated hot water supply system recommended by the current code, the criteria of water flow direction in the pipes of transport and distribution is brought forward based on the hydraulic principle, followed by the analysing with charts of flow directions in the reversed return hot water system consisting of two, three and several vertical pipes in the working conditions of simple return and a little water distributing. There are several directions of circular flow, the only working condition of simple return and single water flow direction which applied in current hydraulic calculation of reversed return hot water supply system is incomplete, certain hydraulic precondition is necessary to ensure circular flow flowing in each vertical pipe as the assumed direction in the course of hydraulic calculation.  相似文献   

20.
Contaminant diffusion in layered soil is very complex. The diffusion process is simplified as a one-dimensional diffusion mode. The Laplace transformation and Laplace numerical inverse transformation are adopted. The proposed solution can be degraded to a single layer case. The obtained results are well consistent with those obtained by the classic theory. The correctness of the presented solution is verified by comparing the calculation results with the results generated by existing numerical software. One case study is conducted and the calculation results have a good agreement with measured data, which prove the reliability of the proposed method. The presented method can be used to solve more complex boundary conditions of contaminant migration.  相似文献   

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