Browsing by Author "Leon, Jorge"
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- ItemChildren's views on evacuation drills and school preparedness: Mapping experiences and unfolding perspectives(2018) Vasquez, Andrea; Marinkovic, Katitza; Bernales, Margarita; Leon, Jorge; Gonzalez, Juan; Castro, Sebastian
- ItemColor development and acrylamide content of pre-dried potato chips(ELSEVIER SCI LTD, 2007) Pedreschi, Franco; Leon, Jorge; Mery, Domingo; Moyano, Pedro; Pedreschi, Romina; Kaack, Karl; Granby, KitThe objective of this work was to study the development of color formation in pre-dried potato slices during frying and acrylamide formation in the final potato chips. Color measurement was done by using an inexpensive computer vision technique which allowed quantifying representatively and precisely the color of complex surfaces such as those of potato chips in L*a*b* units from RGB images. Prior to frying, potato slices (Desiree variety, diameter: 37 mm, width: 2.2 mm) were blanched in hot water at 85 degrees C for 3.5 min. Unblanched slices were considered as the control. Slices of the same dimensions were blanched as in the previous step, and then air-dried until reaching a moisture content of 60% (wet basis). These samples were called pre-dried potato slices. Potato slices were fried at 120 degrees C, 140 degrees C, 160 degrees C and 180 degrees C until reaching moisture contents of similar to 1.8% (total basis) for color quantification. Acrylamide concentration was determined only in final chips fried at 120 degrees C, 150 degrees C and 180 degrees C and compared with that of two brands of commercial chips produced in Chile (Moms and Frito Lay). Color values in L*a*b* units were recorded at different sampling times during frying at the four mentioned temperatures using the total color difference parameter (Delta E). Pre-drying did not affect the color of potato chips considerably when compared against blanched chips; however when fried at 180 degrees C, pre-dried potato chips present 44%, 22%, 44% lower acrylamide content than that of the control, Moms and Frito Lay chips, respectively. (c) 2006 Elsevier Ltd. All rights reserved.
- ItemColor measurement in L*a*b* units from RGB digital images(ELSEVIER, 2006) Leon, Katherine; Mery, Domingo; Pedreschi, Franco; Leon, JorgeThe superficial appearance and color of food are the first parameters of quality evaluated by consumers, and are thus critical factors for acceptance of the food item by the consumer. Although there are different color spaces, the most used of these in the measuring of color in food is the L*a*b* color space due to the uniform distribution of colors, and because it is very close to human perception of color. In order to carry out a digital image analysis in food, it is necessary to know the color measure of each pixel on the surface of the food item. However, there are at present no commercial L*17*b* color measures in pixels available because the existing commercial colorimeters generally measure small, non-representative areas of a few square centimeters. Given that RGB digital cameras obtain information in pixels, this article presents a computational solution that allows the obtaining of digital images in L*a*b* color units for each pixel of the digital RGB image. This investigation presents five models for the RGB -> L*a*b* conversion and these are: linear, quadratic, gamma, direct, and neural network. Additionally, a method is suggested for estimating the parameters of the models based on a minimization of the mean absolute error between the color measurements obtained by the models, and by a commercial colorimeter for uniform and homogenous surfaces. In the evaluation of the performance of the models, the neural network model stands out with an error of only 0.93%. On the basis of the construction of these models, it is possible to find a L*a*b* color measuring system that is appropriate for an accurate, exacting and detailed characterization of a food item, thus improving quality control and providing a highly useful tool for the food industry based on a color digital camera. (c) 2006 Elsevier Ltd. All rights reserved.
- ItemDevelopment of a computer vision system to measure the color of potato chips(ELSEVIER, 2006) Pedreschi, Franco; Leon, Jorge; Mery, Domingo; Moyano, PedroThe objective of this research was to design and implement an inexpensive computer vision system for measuring the color of a highly heterogeneous food material not only in shape as well in color such as potato chips in L*a*b* units from RGB images. The system was composed of (i) a digital color camera for acquiring the images in a digital format, (ii) a computer for storage the images, (c) image analysis routines integrated into a software programmed in Matlab that converts the color RGB of the food image into L*a*b* units. In this way the color of potato chips can be calculated in L*a*b* units over representative areas and in a reproducible way. The kinetics of color changes in potato slices during frying at four temperatures was followed using the implemented computer vision system (CVS). Color values in L*a*b* units were recorded at different sampling times during frying at the four oil temperatures using the total color change parameter (AE). Chips fried at higher temperatures get darker as expected and showed by the CVS. The implemented computer vision system can be used to study as well foods different from potato chips by selecting their proper settings for image acquisition and digital image processing. (c) 2006 Elsevier Ltd. All rights reserved.
- ItemFrom urban form analysis to metrics for enhancing tsunami evacuation: Lessons from twelve Chilean cities(ELSEVIER, 2021) Leon, Jorge; Vicuna, Magdalena; Ogueda, Alonso; Guzman, Simon; Gubler, Alejandra; Mokrani, CyrilIn the case of near-field tsunami emergencies, evacuation is considered the most important and effective method to save human lives. While significant efforts have been carried out to examine the relationships between urban forms and tsunami evacuation, challenges remain on delivering evidence-based urban design strategies, principles or metrics that could be applied by decision-makers to guide the physical development or retrofitting of tsunami-prone coastal communities around the world. In this paper, we propose a methodology that combines tsunami flood and evacuation modelling with statistical analysis, to examine the pedestrian evacuation potential of 67 urban samples extracted from 12 case studies in Chile. Our findings show that urban form parameters like the number of exit points out of an endangered area, the mean distance from the street network to these points, and the population density, can have a noticeable impact on tsunami evacuation times, which nonetheless is significantly dependent on the evacuees & rsquo; departure time. Moreover, we demonstrate that Chilean urban coastal development has been noticeably carried out through grid-like form patterns that might contribute to hinder evacuation in case of a tsunami emergency.
- ItemUrban form planning and tsunami risk vulnerability: Analysis of 12 Chilean coastal cities(2022) Vicuña Del Rio, Maria Magdalena; Leon, Jorge; Guzmán Pincheira, Simón AndrésUrban form has a significant impact on risk. Spatial planning instruments can optimize urban form in areas exposed to hazards. This work discusses how urban planning instruments, specifically Communal Regulatory Plans (CRPs), affect vulnerability to the risk of tsunami inundation in Chilean coastal cities. We analyze urban form and address exposure, susceptibility, and response capacity parameters. Exposure is evaluated by comparing existing and planned densities and to what extent planned risk areas coincide with inundation zones. We analyze existing critical facilities and land uses permitted by the CRP in inundation zones to evaluate susceptibility. We explore response capacity through the street network connectivity and green areas outside the inundation zone and how CRPs influence the structuring of new roads and new green spaces. We found that CRPs do not hold the sufficient capacity to incorporate and manage the tsunami inundation risk adequately. The planning scenario leads to a systematic increase in vulnerability as cities develop in exposed areas. We suggest to strengthen CRPs capacities to prevent the construction and reconstruction of areas affected by tsunamis, reinforcing the urban fabric's potential for evacuation, and to strengthen joint work between municipal urban planning and disaster risk management departments, among other recommendations.
- ItemUrban form planning and tsunami risk vulnerability: Analysis of 12 Chilean coastal cities(PALGRAVE, 2022) Vicuna, Magdalena; Leon, Jorge; Guzman, SimonUrban form has a significant impact on risk. Spatial planning instruments can optimize urban form in areas exposed to hazards. This work discusses how urban planning instruments, specifically Communal Regulatory Plans (CRPs), affect vulnerability to the risk of tsunami inundation in Chilean coastal cities. We analyze urban form and address exposure, susceptibility, and response capacity parameters. Exposure is evaluated by comparing existing and planned densities and to what extent planned risk areas coincide with inundation zones. We analyze existing critical facilities and land uses permitted by the CRP in inundation zones to evaluate susceptibility. We explore response capacity through the street network connectivity and green areas outside the inundation zone and how CRPs influence the structuring of new roads and new green spaces. We found that CRPs do not hold the sufficient capacity to incorporate and manage the tsunami inundation risk adequately. The planning scenario leads to a systematic increase in vulnerability as cities develop in exposed areas. We suggest to strengthen CRPs capacities to prevent the construction and reconstruction of areas affected by tsunamis, reinforcing the urban fabric's potential for evacuation, and to strengthen joint work between municipal urban planning and disaster risk management departments, among other recommendations.