Nauki Techniczne

Archives of Civil Engineering

Zawartość

Archives of Civil Engineering | 2010 | No 3 |

Abstrakt

The annual usage of heat for the demand of heating systems in municipal sector has been estimatedas about 650PJ. It is mostly addressed for the demand of central heating systems and hot waterconsumption. The mode of adopted solutions concerning regulation and control, as well as energymanagement system, essentially influence its consumption. In the case of residential buildings,the costs of energy constitute the greatest share related to the total cost of building maintenance. Providing buildings with modern digital systems for control and regulation of heating installationsis a basic condition enabling their rational usage. In currently employed solutions, algorithms PI or PID are usually applied. However, due to the non-linear properties of heating control systems, they do not secure proper quality. The sequences are often unstable and major control deviationsoccur. The application of neural networks is an alternative solution to those presently employed. They are especially recommended for adaptive control of non-stationary systems. Such cases occurin heating objects since they demonstrate non-linear properties with a great range of variability ofparameters; this especially refers to district heating equipped with flux-through heat exchangers.In this paper, a compile model of heating system control aided by neural networks is presented. The results of the investigation clearly prove the usefulness of such solutions, cause the qualityof control is much better than that one applied in traditional systems. Presently, works on theimplementation of the proposed solutions are under way.

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Autorzy i Afiliacje

W.J. Chmielnicki

Abstrakt

Industrial utilization of fly ash from various kinds of fuel plays an important role in the envi-ronmentally clean and cost effective power production. The primary market for fly ash utilizationis as a pozzolanic addition in concrete production. The paper concerns the concretes containingfly ash called Fly Ash from Biomass (FAB) from co-combustion of hard coal and wood biomass(wood chips). Characterization of the fly ash was carried on by means of X-ray diffractometryand E-SEM/EDS analysis. The results of laboratory studies undertaken to evaluate the influence of FAB on concrete resistance to surface scaling due to cyclic freezing and thawing in the presenceof NaCl solution were presented. The tests were carried out for concretes containing up to 25% offly ash related to cement mass. Additionally, the microstructure of air-voids was described.

It was concluded that the FAB has significant effect on concrete freeze/thaw durability. The re-placement of cement by fly ash from co-combustion progressively transformed the concrete mi-crostructure into less resistant against freeze/thaw cycles and excessive dosage (over 15%) maydangerously increase the scaling.

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Autorzy i Afiliacje

M. Kosior-Kazberuk
D. Jóźwiak-Niedźwiedzka

Abstrakt

The method of calculations of a thick plate on the two-parameter layered foundation by the finiteelement method is presented. The numerical model allows to add a few (number of) foundationlayers. The expressions for the element stiffness matrices of the foundation are based on 18-nodezero-thickness interface elements. For modelling of thick plates the 9-node Mindlin element of theLagrange family is used. The formulation of the problem takes into account the shear deformation ofthe plate and unilateral contact conditions between plate and foundation. The tensionless characterof the foundation is achieved by removing from the global stiffness matrix the appropriate partof foundation stiffness attached to the node being in the separation stage. The advantages of theproposed algorithm are illustrated by numerical examples.

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Autorzy i Afiliacje

R. Buczkowski
W. Torbacki

Redakcja

Editor-in-Chief
Henryk Zobel


Scientific Advisory Committee
:
Andrzej M. Brandt
Werner Brilon (Germany)
Jacek Chróścielewski
Luc Courard (Belgium)
Andrzej Garbacz
Andrzej Garstecki
Wojciech Gilewski
Marian Giżejowski
Oleg Kapliński
Piotr Konderla
Aleksander Kozłowski
Marian Kwietniewski
Zbigniew Młynarek
Andrzej S. Nowak (USA)
Anna Siemińska-Lewandowska
Jan Szwabowski
Waldemar Świdziński
Andrew P. Tarko (USA)
Marian Tracz
Edmundas K. Zavadskas (Lithuania)
Jerzy Ziółko

Secretary
Dorota Walesiak

Kontakt

 

Politechnika Warszawska

Wydział Inżynierii Lądowej

Al. Armii Ludowej 16, 00-637 Warszawa, Polska Pokój 618; Telefon 22 234 62 84

e-mail: ace@il.pw.edu.pl;

website: http://ace.il.pw.edu.pl

 

 

 

Polityka Open Access

Archives of Civil Engineering jest czasopismem wydawanym w wolnym dostępie na licencji CC BY-NC-ND 4.0. https://creativecommons.org/licenses/by-nc-nd/4.0/

Archives of Civil Engineering is an open access journal with all content available with no charge in full text version. The journal content is available under the licencse CC BY-NC-ND 4.0 https://creativecommons.org/licenses/by-nc-nd/4.0/.

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