Earthen architecture, tradition and modernity: Local self construction through building tradition and technological innovation opportunities in Chiapas, MexicoKarla Sánchez Torres
, 2015, doctoral dissertation
Abstract: Earthen architecture represents a long building tradition of numerous indigenous communities in Mexico, in particular in the state of Chiapas, where a significant number of examples represent a rich historical tradition of earthen architecture and a valuable source of information, hence a fertile ground for a deeper investigation on its potential significance and, more broadly, for a greater understanding of sustainable building today.
Despite the fact that the relevance of earthen architecture is widespread all over the world, traditional earthen architecture in Chiapas is scarcely documented, it lacks systematic research projects aimed at preserving this important tradition of these indigenous groups who often live in precarious conditions. Hence, this research highlights not only the widespread employment of earth as a traditional building material for the indigenous groups of Chiapas, but also its additional function as being an authentic expression of the architectural legacy of indigenous culture and thus a key potential factor for the development of the self construction.
The first part of the dissertation introduces a general overview and prevailing knowledge on earthen architecture, mainly through investigating the bibliographic, historical and technical sources as well as the particular studies on earthen architecture in Mexico. The second part discusses the results of the field studies related to the specific conditions of earthen architecture in Chiapas through sampling, testing, photographic reference and interviews.
On analysing the results of the field studies it can be established that the local population has shown a particular interest in the continuity of the earthen building tradition, in spite of this period of far-reaching globalisation building trends.
For this reason the final part of dissertation propooses the manual. The main objective of the manual is to improve the traditional earthen building system by introducing a number of minor variations to the building technologies and new sustainable suggestions for the management of the living space, without sacrificing the flair and simplicity found within the local building tradition, thus giving new opportunities for the development of local populations through the preservation of the earthen building tradition.
Found in: ključnih besedah
Keywords: earthen architecture, indigenous, self-construction, manual, tradition, local communities
Published: 01.12.2015; Views: 2286; Downloads: 21
Fulltext (34,58 MB)
Meshless modeling of thermo-mechanics of low-frequency electromagnetic direct chill castingBoštjan Mavrič
, 2017, doctoral dissertation
Abstract: The aim of this dissertation is to devise a meshless model describing the thermomechanical phenomena, which occur during DC casting of aluminium alloys under the influence of electromagnetic stirring. The thermoemchanical phenomena are important, because they can cause several type of defects, which can significantly deteriorate the quality of the resulting billet. The two most important of them are the hot tearing, which causes cracks to appear in the mushy zone, and the porosity, which demonstrates itself as micrometer sized voids in the microstructure of the billet.
To calculate the stresses and strains, a computational model of the stationary state of the process, stated in axial symmetry, is formulated. It uses Eulerian formulation by fixing the computational domain to the mold of the casting device allowing the material to move through the computational domain. The stresses are calculated from the stress equilibrium equations. The small strain approximation is used to consider the three contributions to strain. The strain consists of the thermal strain, which is caused by the inhomogeneous thermal profile in the billet, the viscoplastic strain, which is caused by the irreversible deformation because of the large stresses occurring in the billet, and the elastic strain.
The spatial discretization of the governing equations is performed by local radial basis function collocation method (LRBFCM) and the temporal discretization is achieved by the method of lines with implicit Euler formula. The method used for spatial discretization uses radial basis functions augmented by monomials to approximate the solution values on localized stencils. This approximation is used to construct the discretization coefficients of the differential operators present in the model. A flexible framework for formulation of multiphysics problems is developed to use the obtained discretization coefficients to construct the temporal discretization of the governing equations. The node arrangement, on which the spatial discretization is performed, was generated by a point-repel algorithm.
The performance of the method is tested on several benchmark test cases. The accuracy of the discretization is estimated by comparing the analytic and the numerical solution to several stationary problems in thermomechancis. Of special interest is the performance of the method with respect to the choice of the shape parameter, which determines the spatial scale of the radial basis functions. Besides this, the dependence of the condition number of the interpolation matrix on the shape parameter is studied. The condition number is found fit to replace the condition number as the shape-determining free parameter of the method.
The implementation of the solver of time dependent problems is tested on problem of thermoelasticity, which couples the thermal transport with the elastic waves. The results of the problem are compared with the finite element method, showing good agreement of the two methods. The results are also compared with the results obtained by meshless local Petrov-Galerkin method and the proposed local collocation method demonstrated significantly better solution quality in the studied case.
The performance of the solver used to solve the system of nonlinear equations given by the viscoplastic constitutive equations is estimated on a quasi zero-dimensional problem. The results are found to match perfectly. Solution of a more complicated problem is obtained with the proposed method and the finite-element method, both methods giving practically the same solution, although some serious limitations of the chosen finite element solver are exposed during the selection of the problem parameters.
Finally, the devised method is applied to the problem of DC casting of aluminium alloys. The thermomechanical model relies on a model of heat and mass transfer to obtain the input fields needed in the solver. The required fields are: temperature, pressure, liquid
Found in: ključnih besedah
Summary of found: ...of the governing equations is performed by local radial basis function collocation method (LRBFCM) and...
Keywords: thermomechanics, viscoplasticity, aluminium alloys, direct-chill casting, electromagnetic stirring, hot tearing, porosity, meshless methods, local collocation method, radial basis functions, shape parameter
Published: 28.06.2017; Views: 2097; Downloads: 78
Fulltext (21,30 MB)
Drifting through CityscapesSzabolcz Kisspal
, Allan Siegel
, Eszter Lazar
, Olivera Batajić Sretenović
, Danica Bojić
, 2018, professional monograph
Found in: ključnih besedah
Summary of found: ... local, city, urban, mapping, intermedia...
Keywords: local, city, urban, mapping, intermedia
Published: 06.06.2018; Views: 1048; Downloads: 21
Fulltext (237,37 MB)
Comparison and complementary use of in situ and remote sensing aerosol measurements in the Athens Metropolitan AreaS. Vratolis
, Griša Močnik
, Konstantinos Eleftheriadis
, 2020, original scientific article
Abstract: In the summer of 2014 in situ and remote sensing instruments were deployed in Athens, in order to study the concentration, physical properties, and chemical composition of aerosols. In this manuscript we aim to combine the measurements of collocated in situ and remote sensing instruments by comparison and complementary use, in order to increase the accuracy of predictions concerning climate change and human health. We also develop a new method in order to select days when a direct comparison on in situ and remote sensing instruments is possible. On selected days that displayed significant turbulence up to approximately 1000 m above ground level (agl), we acquired the aerosol extinction or scattering coefficient by in situ instruments using three approaches. In the first approach the aerosol extinction coefficient was acquired by adding a Nephelometer scattering coefficient in ambient conditions and an Aethalometer absorption coefficient. The correlation between the in situ and remote sensing instruments was good (coefficient of determination equal to 0.69). In the second approach we acquired the aerosol refractive index by fitting dry Nephelometer and Aethalometer measurements with Mie algorithm calculations of the scattering and absorption coefficients for the size distribution up to a maximum diameter of 1000 nm obtained by in situ instruments. The correlation in this case was relatively good ( equal to 0.56). Our next step was to compare the extinction coefficient acquired by remote sensing instruments to the scattering coefficient calculated by Mie algorithm using the size distribution up to a maximum diameter of 1000 nm and the equivalent refractive index (), which is acquired by the comparison of the size distributions obtained by a Scanning Mobility Particle Sizer (SMPS) and an Optical Particle Counter (OPC). The agreement between the in situ and remote sensing instruments in this case was not satisfactory ( equal to 0.35). The last comparison for the selected days was between the aerosol extinction Ångström exponent acquired by in situ and remote sensing instruments. The correlation was not satisfactory ( equal to 0.4), probably due to differences in the number size distributions present in the air volumes measured by in situ and remote sensing instruments. We also present a day that a Saharan dust event occurred in Athens in order to demonstrate the information we obtain through the synergy of in situ and remote sensing instruments on how regional aerosol is added to local aerosol, especially during pollution events due to long range transport.
Found in: ključnih besedah
Summary of found: ...on how regional aerosol is added to local aerosol, especially during pollution events due to...
Keywords: Aerosol mixing in the vertical, In situ — Remote sensing comparison, Regional aerosol addition to local aerosol
Published: 09.04.2020; Views: 339; Downloads: 0
Fulltext (3,98 MB)