Numer: Autor: Fraza:

XL, 3-4 (1993)

Mathematical model of the process of hot water consumption

Władysław Szaflik

Institute of Water Engineering of the Technical University of Szczecin,
Al. Piastów 50, 70-311 Szczecin, Poland

Streszczenie

The problem of stochastic modelling of hot-water intake for the needs of dimensioning of the system serving its preparation has been considered. Modelling of hot water intake was carried out using Poisson's process with variable intensity. Further, the theoretical distribution of variability of the total hot-water intake over an optional period of time has been defined for the multi-family dwellings, on the basis of experimental results, unitary hot-water consumption for workdays, free days (free Saturdays) and holidays (Sundays) as a function of the number of inhabitants and assumed probability of its being exceeded has been evaluated.

Słowa kluczowe:

On the averaged inertia method in the MHD vicous flow in a slot between fixed surfaces of revolution

Anna Walicka

Higher College of Engineering (WSI),
ul. Podgórna 50, 65-246 Zielona Góra, Poland

Streszczenie

The steady laminar MHD flow of a viscous fluid through a narrow space between two fixed surfaces of revolution, having a common axis of symmetry is considered. To solve this problem the MHD boundary layer equations are used and expressed for the axially symmetric case in a curvilinear orthogonal coordinate system x, Θ, y connected with one of the surfaces. The method of averaged inertia terms is used to solve the boundary layer equations. As a result, one obtains formulae expressing such flow parameters as the velocity components vx, vy and the pressure p.

Słowa kluczowe:

Application of the Saint-Venant model to the problem of the enforced outflow from a drainage channel

Jan Jełowicki

Department of Mathematics, Agricultural Academy,
ul. Grunwaldzka 52, 50-375 Wrocław, Poland

Streszczenie

The Saint-Venant open channel model is applied to the simulation of pump-enforced outflow from a drainage channel. The switching boundary conditions are formulated and used to predict the moment of flow stability loss and for stability control.

Słowa kluczowe:

Optimal ground water pumping model

Andrzej Wit, Agnieszka Czachowska-Aussenberg

Institute of Meteorology and Water Management, Warsaw, Poland

Streszczenie

The paper presents possibilities of application of linear programming to optimize water pumping from an aquifer using vertical wells. An optimization model is described, in which so-called "response coefficients" characterizing lowering of the ground water table in some points of the aquifer, resulting from unit water discharge from individual wells, are used. The methods of calculating response coefficients are given for both confined and unconfined ground water flow. The objective function and constraints for the problem of minimization of total discharge from a group of wells dewatering an excavation have been formulated. The results of application of the optimization model to the problem of dry dock dewatering are presented. To verify the optimal solution resulting from the model, a forecast of ground water level changes has been calculated.

Słowa kluczowe:

Solution of Lamb`s steady-state plane problem for Biot`s medium by the finite element method

Ryszard Staroszczyk

Institute of Hydro-Engineering, Polish Academy of Sciences,
ul. Kościerska 7, 80-953 Gdańsk, Poland

Streszczenie

In the paper plane Lamb's problem for a two-phase medium is solved by the use of the finite element method. In order to reduce considerations to a finite domain artificial boundaries, consisting of viscous dashpots, are introduced. Discrete results obtained are compared with those evaluated analytically.

Słowa kluczowe:

Time dependent increase of bearing capacity of piles driven into cohesive soils

Bohdan Zadroga

Gdańsk Technical University, Hydro-Engineering Faculty,
ul. Narutowicza 11, 80-952 Gdańsk, Poland

Streszczenie

A time influence on bearing capacity increase of driven piles is presented. The field investigation results for different types of piles driven in various soil conditions obtained by various authors were analysed. In the paper the most significant quantitative relations and calculation formulae are given. The methodology and scope of own model tests for open-ended and closed-ended pipe piles driven in till was discussed. The comparison results of measured and calculated values of piles bearing capacities as a function of time was presented. It has been finally stated, that the total bearing capacity increase of piles is caused mainly by capacity increase of pile shaft.

Słowa kluczowe: