جستجوی مقالات مرتبط با کلیدواژه « Height » در نشریات گروه « عمران »

Nowadays, surface roughness measurement has been considered in many civil and industrial applications. One of the important indicators in measuring the roughness of the surface, is determining the fractal dimension. To determine the fractal dimension, the profile meters are usually used by contact method, which in the case of surfaces with low roughness may cause distortion of the surface texture and as a result, the roughness is measured with low accuracy. In this study, a fast and reliable method based on close range photogrammetry, which is a non-contact method, for measuring fractal dimension and roughness is presented. The case study in this research is the sand surface.. Digital elevation model was created by taking several overlapped photographs. For accurate measurements on the surface 6 control points were created, then scaling and definition of the coordinate system was performed. The accuracy in x-y plane is 1.33 mm and the height accuracy is 0.32 mm. In order to measure the surface roughness parameters including correlation length and root mean square height (rms-height), several profiles were extracted from the three-dimensional surface. The slope of the surface spectrum was calculated using Welch method for each of these profiles then the fractal dimensions were calculated. Finally, using the fractal dimension, the correlation length and rms-height were calculated for each of the profiles. In this study, surface roughness was evaluated using four indices of fractal dimension, correlation length, rms-height and ZS parameter (ratio of rms-height to correlation length). ‌ The results showed that for all profiles, ZS with 81% correlation coefficient with fractal dimension, is a sufficient indicator for calculating the surface roughness, because of the the independence of this indicator from the length of the profile. This study showed that the close-range photogrammetry is a very suitable and reliable method for measuring roughness parameters. One of the important advantages of this method, unlike other methods such as needle or laser profile meters, is having multiple profiles in any desired direction and preserve of texture (especially on very low roughness surfaces) due to direct contact of the profile meter with the surface.

Rapid urbanization and urban growth are important issues to be considered. Urban development factors recognition can help urban planners and decision makers to understand the consequences of their decisions on urban growth and development .So urban planners, in order to Control the urban growth, use dynamic systems .cellular automata (CA) models have been increasingly used over the last decades to simulate a wide range of spatial phenomena.Urban development is a complex spatio-temporal process that involves both horizontal and vertical growth. Despite growing recognition of the significance of horizontal development, models of urban vertical growth remain limited .This study aims to develop a GIS-based vector cellular automata model for exploring the Horizontal growth and vertical complexities of urban growth according to the height states of existing buildings in the neighborhood and using General Development Control Regulations.The developed model has the capacity to simulate urban growth space and hence vertical growth .series of variables that are used in horizontal model including accessibility, physical suitibility , neighborhood affect and land price.Affactive factors of urban development are classified in two part: vertical variables and horizontal variables .Slope and Height factors will be used in order to calculate the phizical suitability for undevelop parcel. Euclidean distance and network distance will be used in order to calculate accessibility. neighborhood affect is considered in three component. Also Value of residential, office and retail floor area are computed for property values affect.
Vertical model was performed in two different ways. In the first method, undevelop Parcel is assigned a state value according to the height states of existing buildings in the neighborhood in which it is situated. In the second method, using General Development Control Regulations can simulate different height states of building growth. the model has been developed in a very small area of ​​the city of Qom in the years 1385 to 1394 .The results show overall accuracy 60% in horizontal growth and overall accuracy 65 % in the first method of vertical growth and overall accuracy 60 % in the second method of vertical growth .Therefore, it carries scope of being used to visualize growth for other, similar, cities and help urban planners and decision makers to understand the consequences of their decisions on urban growth and development.