scholarly journals Hydraulic networks with pressure-dependent closure relations, under restrictions on the value of nodal pressures. Maxwell matrix properties and monotonicity of flow distribution problem solution

2019 ◽  
Vol 102 ◽  
pp. 01005 ◽  
Author(s):  
Leonid Korelstein
Keyword(s):  
Existence Theorems ◽  
Flow Distribution ◽  
Previous Article ◽  
Problem Solution ◽  
Distribution Problem ◽  
Matrix Properties ◽  
Hydraulic Network ◽  
Closure Relations ◽  
Hydraulic Networks

In the article, which continues the research of article [1], the results of previous article are generalized to “abstract” hydraulic networks. Additional existence theorems are proved for classical flow distribution problem (CFDP) for hydraulic networks with pressure-dependent closure relations, under restriction on nodal pressures. Hydraulic network Maxwell matrix properties are establish, related to monotonicity of CFDP solution.

scholarly journals Existence, uniqueness and monotonic behavior of the solution of classical flow distribution problem for hydraulic networks with pressure-dependent closure relations

2019 ◽  
Vol 102 ◽  
pp. 01004 ◽  
Author(s):  
Leonid Korelstein
Keyword(s):  
Existence And Uniqueness ◽  
Flow Distribution ◽  
Uniqueness Of Solution ◽  
Distribution Problem ◽  
Closure Relation ◽  
Closure Relations ◽  
Monotonicity Conditions ◽  
Hydraulic Networks

Existence, uniqueness and monotonic behavior of the solution of classical flow distribution problem for hydraulic networks with pressure-dependent closure relations was proved. The closure relation can have very general form, restricted only by continuity and monotonicity conditions necessary for providing existence, uniqueness and continuity of flow distribution problem for each branch. It is shown that network as a whole “inherits” monotonicity and continuity of its branches behavior, and this provides existence and uniqueness of solution.

scholarly journals Modernization of Todini Global Gradient Algorithm for hydraulic analysis of networks with choked flow

2020 ◽  
Vol 219 ◽  
pp. 01003
Author(s):  
Leonid Korelstein
Keyword(s):  
Network Flow ◽  
Flow Distribution ◽  
Gradient Algorithm ◽  
Hydraulic Analysis ◽  
Distribution Problem ◽  
Choked Flow ◽  
Global Gradient Algorithm ◽  
Hydraulic Network ◽  
Piping Networks ◽  
Gas Liquid Flow

The modification of well-known Global Gradient Algorithm for hydraulic network flow distribution problem is proposed. This modification is based on problem equations rewritten in “upstream” form and on modified form of linearization, and can be effectively used for piping networks with gas and multiphase gas-liquid flow with multiple choked flow.

scholarly journals A method of analysis of complex hydraulic networks

2020 ◽  
Vol 219 ◽  
pp. 01002
Author(s):  
Leonid Duginov ◽  
Michael Rozovskiy ◽  
Leonid Korelstein
Keyword(s):  
Loss Function ◽  
Flow Rate ◽  
Network Flow ◽  
Solution Method ◽  
Iterative Solution ◽  
Distribution Problem ◽  
Rate Distribution ◽  
Hydraulic Network ◽  
Hydraulic Networks ◽  
Iterative Solution Method

A simple and reliable iterative solution method of classical hydraulic network flow rate distribution problem is described. The method is based on chord linearization of inverse branch loss function which keeps basic branch properties. It has good speed of convergency which is practically independent of initial values.

scholarly journals METHODS AND ALGORITHNS FOR INCREASING THE SPEED OF COMPU-TING PROCESSES FOR CALCULATING HYDRAULIC NETWORKS

2019 ◽  
Vol 7 (3) ◽  
pp. 55-61
Author(s):  
Elena Kitayceva
Keyword(s):  
Mathematical Modeling ◽  
Nonlinear Equations ◽  
Network Topology ◽  
Iterative Process ◽  
Flow Distribution ◽  
System Of Nonlinear Equations ◽  
System Of Equations ◽  
Hydraulic Network ◽  
Hydraulic Networks ◽  
The Mathematical Model

The article is devoted to mathematical modeling of flow distribution in hydraulic net-works. Calculations of hydraulic networks are carried out at the stage of their design and operation. The results of numerical simulation are used to control the operation of the hy-draulic network in real time. The mathematical model of the distribution of flows in the hydraulic network is a system of nonlinear equations. The nodal pressures method used to solve the system of equations numerically is the n-dimensional Newton method. To ensure stable and fast convergence of the iterative process, it is proposed to use the initial approx-imation taking into account the network topology and parameters of its objects, use the lower relaxation factor and optimize the structure of the Maxwell matrix. The algorithms presented in the paper allow one to significantly reduce the dimension of the system of nonlinear equations being solved.

Optimal Selection of Pumps in an Hydraulic Network

1976 ◽  
Vol 98 (1) ◽  
pp. 2-9 ◽  
Author(s):  
T. F. Conry ◽  
D. P. Schneider
Keyword(s):  
Control Systems ◽  
Mixed Integer ◽  
Nonlinear Program ◽  
Hydraulic Control ◽  
Analysis Problem ◽  
Analysis And Design ◽  
Hydraulic Network ◽  
Hydraulic Networks ◽  
Selection Of ◽  
General Networks

The selection of pumps in an hydraulic network (such as those found in plant firewater systems or hydraulic control systems) is formulated as a mixed integer nonlinear program. The design objective is to minimize the total relative pump first cost. The piping network is assumed to exist and hence is not modified during the optimization process. A method is given for the transformation of the mixed integer nonlinear program into a mixed integer separable program. This formulation allows the use of efficient algorithms for the design of hydraulic networks. It also offers an alternative for the analysis of hydraulic networks. This technique may also be used for the analysis and design of general networks with nonlinear elements subject to convexity conditions. Two examples are given which consider an analysis problem and a design problem.

scholarly journals The identification problem solution of the ventilation system model based on static pressure

2019 ◽  
Vol 102 ◽  
pp. 01003
Author(s):  
Dmitriy V. Boykov ◽  
Aleksandr A. Dekterev
Keyword(s):  
Static Pressure ◽  
Ventilation System ◽  
Flow Distribution ◽  
Identification Problem ◽  
Pipeline System ◽  
Problem Solution ◽  
Local Resistance ◽  
Identification Method ◽  
Gas Removal ◽  
Resistance Coefficients

A pressure method to solve the problem of flow distribution in a pipeline system based on the static pressure use was proposed in the study. A modification of the identification method to search for the local resistance coefficients of the ventilation system sites was provided. Static pressure and flow rate as identifying values were used in the developed approach. The applicability of the identification method for local resistance of the gas removal system to be found was shown.

The Effect of Mass Flow Distribution Inaccuracies in a Hydraulic Network Model for OD Zig-Zag Cooled Power Transformer Windings

2015 ◽  
Vol 789-790 ◽  
pp. 336-341
Author(s):  
Joris Coddé ◽  
Wim Van der Veken ◽  
Martine Baelmans
Keyword(s):  
Mass Flow ◽  
Cfd Simulation ◽  
Power Transformer ◽  
Flow Distribution ◽  
Network Models ◽  
Good Correspondence ◽  
Transformer Winding ◽  
Hydraulic Network ◽  
Transformer Design ◽  
Simulation Results

In this paper the mass flow distribution in zig-zag cooled power transformer windings is shown to play a crucial factor to accurately predict the winding temperature. In order to enable thermo-hydraulic network models for transformer design, new correlations are derived for combining and dividing T-junctions and elbow configurations. Good correspondence is achieved in comparison with CFD simulation results for a zig-zag cooled power transformer winding.

On the Area of Equilibrium Thermodynamics Application

2004 ◽  
Author(s):  
Boris M. Kaganovich ◽  
Alexandre V. Keiko ◽  
Vitalii A. Shamansky ◽  
Igor A. Shirkalin
Keyword(s):  
Chemical Kinetics ◽  
Gas Turbines ◽  
Flow Distribution ◽  
Stationary Flow ◽  
Time Variable ◽  
Combustion Chambers ◽  
Equilibrium Thermodynamics ◽  
Transfer Processes ◽  
Intermediate States ◽  
Hydraulic Networks

The paper addresses the applicability of equilibrium thermodynamics models and the expediency of their employment for analysis of non-equilibrium systems, first of all, when solving the applied computational problems of large dimensionality. A model of extreme intermediate states (MEIS) is suggested for such an analysis. The methods to include the constraints on chemical kinetics and transfer processes are discussed. These constraints are to be presented in a thermodynamic form, i.e. without time variable. The efficiency of the approach is illustrated with the examples of determining the maximum possible nitrogen oxide concentrations in combustion chambers of gas turbines and modeling the non-stationary flow distribution in multi-loop hydraulic networks.

In Search of Somatic Precursors of Spontaneous Insight

2018 ◽  
Vol 32 (3) ◽  
pp. 97-105 ◽  
Author(s):  
Wangbing Shen ◽  
Yuan Yuan ◽  
Chaoying Tang ◽  
Chunhua Shi ◽  
Chang Liu ◽  
...  
Keyword(s):  
Problem Solving ◽  
Direct Evidence ◽  
Electrodermal Activity ◽  
Cardiovascular Responses ◽  
Solution Time ◽  
Problem Solution ◽  
Insight Problem ◽  
Creative Insight ◽  
Insight Problem Solving ◽  
Analytic Problem

Abstract. A considerable number of behavioral and neuroscientific studies on insight problem solving have revealed behavioral and neural correlates of the dynamic insight process; however, somatic correlates, particularly somatic precursors of creative insight, remain undetermined. To characterize the somatic precursor of spontaneous insight, 22 healthy volunteers were recruited to solve the compound remote associate (CRA) task in which a problem can be solved by either an insight or an analytic strategy. The participants’ peripheral nervous activities, particularly electrodermal and cardiovascular responses, were continuously monitored and separately measured. The results revealed a greater skin conductance magnitude for insight trials than for non-insight trials in the 4-s time span prior to problem solutions and two marginally significant correlations between pre-solution heart rate variability (HRV) and the solution time of insight trials. Our findings provide the first direct evidence that spontaneous insight in problem solving is a somatically peculiar process that is distinct from the stepwise process of analytic problem solving and can be represented by a special somatic precursor, which is a stronger pre-solution electrodermal activity and a correlation between problem solution time and certain HRV indicators such as the root mean square successive difference (RMSSD).

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