Agnieszka J. Klemm
Glasgow Caledonian University
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Publication
Featured researches published by Agnieszka J. Klemm.
Building and Environment | 2000
Katarzyna Klemm; Wojciech Marks; Agnieszka J. Klemm
This paper presents an example of the optimisation of two building arrangements as a function of three variables describing their alignment relative to each other and relative to North. The presented results are limited to the wind flow speeds around buildings in flat undeveloped terrain. The turbulence model K-ϵ has been adopted for this study. Calculations have been made with the use of simulation program FLUENT 4.3. The potential application of a multicriteria optimisation method for the selection process of the optimal arrangement of buildings which would provide required wind comfort has been investigated. Computer program CAMOS (Computer Aided Multicriterion Optimisation System) has been used for the optimisation procedure.
Building and Environment | 2001
Kazimierz Rozniakowski; Piotr Klemm; Agnieszka J. Klemm
Abstract Preservation of cultural heritage is gaining increasing attention all over the world. Restoration of ancient artwork and architecture requires even more effective cleaning techniques than are currently available. Laser cleaning appears to be a suitable method for removing surface contaminants from porous materials like masonry. This paper presents some effects of laser beam interaction (ruby laser, free generation regime) with clean and contaminated surface of brick which was subjected to long term exposure to atmospheric conditions. The effects of the laser beam interaction have been examined by the optical microscopy method, scanning electron microscopy and X-ray microanalysis. The present research revealed the potential application of laser irradiation for cleaning of the surface layer from contaminants and possible modification of the chemical composition of cleaned surfaces.
Building and Environment | 1997
Agnieszka J. Klemm; Piotr Klemm
Abstract This paper presents results which are part of a larger study on the influence of two admixtures (methyl hydroxy ethyl cellulose, MHEC, and polyvinyl acetate, PVA) on properties of water contained in pores and capillaries of cementitious materials subjected to freezing and thawing. An attempt has been made to explain some aspects of frost deterioration based on the Everett and Hynes model of phase transition. The Differential Scanning Calorimetry technique was used to record the process of water to ice transition in cementitious composites, which were initially subjected to different curing conditions including freezing and thawing. A study of the phase transition of water in polymer modified concrete revealed variations in the ice concentration depending upon the mix composition and number of freezing and thawing cycles. It has been found that admixtures have strong effects on the phase transition particularly after prolonged exposure to alternate freezing and thawing.
Building and Environment | 2002
Agnieszka J. Klemm; Piotr Klemm; Kazimierz Rozniakowski; Tomasz W. Wojtatowicz
This paper present the results of the investigation into a potential application of laser radiation for the detection of phase transition processes occurring on the surface layers of porous materials. An attempt was made to discuss in the approximation equations, the relationships between coefficients of the reflected light, the temperature and humidity of the surrounding environment. Laser light reflected from the porous surface carries information about the roughness of the structure. The presence of water microdrop on the surface of the porous material, as a result of condensation and thus a phase transition, leads to the phase displacement of individual rays, which is represented by different images. Therefore, a comprehensive analysis of the reflected light parameters allows a dynamic study of the phase transition phenomena without mechanical intervention.
Building and Environment | 1998
Agnieszka J. Klemm; Wojciech Marks
Abstract The optimisation approach to any activity in technology, economics or other fields, is aimed at finding methods of determining the best solutions in an objective way. In particular, the optimisation of composite materials deals with problems of selecting the values of several variables which determine composition, microstructure, mixing procedure and curing regime, etc. This paper presents the application of the optimisation approach to the design of frost resistant concrete modified by two admixtures—methyl hydroxy ethyl cellulose, MHEC and polyvinyl acetate, PVA. Experimental data, including flexural and compressive strengths, total porosity and supercooling, all determined after 300 cycles of freezing and thawing was used for the formulation of the objective functions. The problem of optimisation was solved with the aid of the Computer Aided Multicriterion Optimisation System—CAMOS.
Building and Environment | 1997
Agnieszka J. Klemm; Piotr Klemm
Abstract Deterioration of mortars by weathering is usually of great importance and is brought about by the disruptive action of alternate freezing and thawing of free water within the material. As it appears that applications of methyl hydroxy ethyl cellulose (MHEC) and polyvinyl acetate (PVA) are very beneficial in improving frost resistance, special attention has been paid to observing the changes in microstructural features of polymer modified composites exposed to the destructive effects of water and low temperature. The presence of both admixtures in normally cured composites has been found to have a significant effect on their microstructure. The microstructure is mostly determined by the quantity of MHEC used, as it provides water retention. The application of PVA slightly affects the pore size distribution, significantly improving the adhesive properties of composites. The present research revealed an interrelationship between the quantity of admixtures used and the micro-structural features of composites subjected to freezing and thawing. The mercury intrusion porosimetry results suggest the significant effect of rehydration process with respect to the damage caused by the action of crystallised ice.
Building and Environment | 2002
Agnieszka J. Klemm; Piotr Klemm; Kazimierz Rozniakowski; G.H. Galbraith
Abstract This paper presents the results of the larger study on the potential application of laser radiation for the detection of phase transition processes. The proposed experimental method allows a dynamic study of the phenomena without mechanical intervention. This seems to be the best practical solution particularly when the access for the other methods is very restricted. The investigations give an evidence of the strong relationships between the rapid growth of water vapour condensate and the roughness of the surface. Condensation process therefore can be modified by a careful design of the geometrical structure of surface.
Brittle Matrix Composites | 2006
Poologanathan Sanjeevan; Agnieszka J. Klemm; Piotr Klemm
Abstract The paper presents a part of the larger study on microstructural features of mortars and their effect on laser cleaning process. The paper focuses on presenting the results of investigation on the influence of surface roughness, porosity and moisture content of mortars on the removal of graffiti. ND: YAG laser was used for laser cleaning. The properties of this laser are as follow: wavelength (λ): 1.06μm, energy: 500 mJ, pulse duration: 10 μs. The relationship between laser fluence and number of pulses required for the laser cleaning can be divided in two zones which are effective zone and ineffective zone. There is good linear relationship between number of pulses required for laser cleaning and the laser fluence in the effective zone. Surface roughness, porosity and moisture content have strong influence on the laser cleaning process. The effect becomes however negligible for high level of laser fluence. The number of pulses required for the laser cleaning is smaller for smooth, less porous and wet surfaces.
Building and Environment | 2002
Agnieszka J. Klemm; Piotr Klemm; Kazimierz Rozniakowski; Tomasz W. Wojtatowicz
Abstract This paper presents the results of the larger study into a potential application of laser radiation for the detection of phase transition processes in low temperatures occurring on the surface layers of cementitious materials. An attempt was made to identify relationships between the environmental conditions—temperature and air humidity, and the selected parameters of the reflected light. Onset of the condensation process and formation of water microdrops on the surface of the material leads to the phase displacement of individual laser rays, which are represented by different speckle images. Although the analysis of parameters of the reflected light are very difficult in the case of porous materials because of highly developed roughness of the surface structure it has been proved that a dynamic study of the phase transition phenomena can be successfully carried out without mechanical intervention.
Building and Environment | 1997
Agnieszka J. Klemm; Piotr Klemm
Abstract This paper reports results from a larger study on the influence of two admixtures (methyl hydroxy ethyl celullose, MHEC and polyvinyl acetate, PVA) on properties of water contained in pores and capillaries of cementitious materials subjected to freezing and thawing cycles. The Differential Scanning Calorimetry technique has been found to be particularly useful in evaluating the amount of heat that is involved as material undergoes either an endothermic or an exothermic transition. An attempt has been made to explain some aspects of phase transition based on the Everett and Hynes model. Test results have shown that the lowest values of ice concentration were recorded for composites which had the lowest MHEC contents and finer microstructure.