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1.
Supplementary material for paper City size and the spreading of COVID-19 in Brazil
Haroldo V. Ribeiro, Andre S. Sunahara, Jack Sutton, Matjaž Perc, Quentin S. Hanley, 2020, izvirni znanstveni članek

Opis: The current outbreak of the coronavirus disease 2019 (COVID-19) is an unprecedented example of how fast an infectious disease can spread around the globe (especially in urban areas) and the enormous impact it causes on public health and socio-economic activities. Despite the recent surge of investigations about different aspects of the COVID-19 pandemic, we still know little about the effects of city size on the propagation of this disease in urban areas. Here we investigate how the number of cases and deaths by COVID-19 scale with the population of Brazilian cities. Our results indicate small towns are proportionally more affected by COVID-19 during the initial spread of the disease, such that the cumulative numbers of cases and deaths per capita initially decrease with population size. However, during the long-term course of the pandemic, this urban advantage vanishes and large cities start to exhibit higher incidence of cases and deaths, such that every 1% rise in population is associated with a 0.14% increase in the number of fatalities per capita after about four months since the first two daily deaths. We argue that these patterns may be related to the existence of proportionally more health infrastructure in the largest cities and a lower proportion of older adults in large urban areas. We also find the initial growth rate of cases and deaths to be higher in large cities; however, these growth rates tend to decrease in large cities and to increase in small ones over time.
Ključne besede: COVID-19, coronavirus, scaling, city size, epidemic, prediction
Objavljeno: 19.11.2020; Ogledov: 277; Prenosov: 69
.pdf Raziskovalni podatki (6,89 MB)
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2.
City size and the spreading of COVID-19 in Brazil
Haroldo V. Ribeiro, Andre S. Sunahara, Jack Sutton, Matjaž Perc, Quentin S. Hanley, 2020, izvirni znanstveni članek

Opis: The current outbreak of the coronavirus disease 2019 (COVID-19) is an unprecedented example of how fast an infectious disease can spread around the globe (especially in urban areas) and the enormous impact it causes on public health and socio-economic activities. Despite the recent surge of investigations about different aspects of the COVID-19 pandemic, we still know little about the effects of city size on the propagation of this disease in urban areas. Here we investigate how the number of cases and deaths by COVID-19 scale with the population of Brazilian cities. Our results indicate small towns are proportionally more affected by COVID-19 during the initial spread of the disease, such that the cumulative numbers of cases and deaths per capita initially decrease with population size. However, during the long-term course of the pandemic, this urban advantage vanishes and large cities start to exhibit higher incidence of cases and deaths, such that every 1% rise in population is associated with a 0.14% increase in the number of fatalities per capita after about four months since the first two daily deaths. We argue that these patterns may be related to the existence of proportionally more health infrastructure in the largest cities and a lower proportion of older adults in large urban areas. We also find the initial growth rate of cases and deaths to be higher in large cities; however, these growth rates tend to decrease in large cities and to increase in small ones over time.
Ključne besede: COVID-19, coronavirus, scaling, city size, epidemic, prediction
Objavljeno: 12.11.2020; Ogledov: 224; Prenosov: 115
.pdf Celotno besedilo (1,23 MB)
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3.
Estimating the size of plants by using two parallel views
Barbara Videc, Jurij Rakun, 2017, izvirni znanstveni članek

Opis: This paper presents a method of estimating the size of plants by using two parallel views of the scene, taken by a common digital camera. The approach relays on the principle of similar triangles with the following constraints: the resolution of the camera is known; the object is always in parallel to the camera sensor and the intermediate distance between the two concessive images is available. The approach was first calibrated and tested using one artificial object in a controlled environment. After that real examples were taken from agriculture, where we measured the distance and the size of a vine plant, apple and pear tree. By comparing the calculated values to measured values, we concluded that the average absolute error in distance was 0.11 m or around 3.7 %, and the absolute error in high was 0.09 m or 4.6 %.
Ključne besede: digital image processing, size, digital camera, pixels, similar triangles
Objavljeno: 10.10.2018; Ogledov: 564; Prenosov: 233
.pdf Celotno besedilo (727,92 KB)
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4.
Determining the grain size distribution of granular soils using image analysis
Nihat Dipova, 2017, izvirni znanstveni članek

Opis: Image-processing technology includes storing the images of objects in a computer and processing them with the computer for a specified purpose. Image analysis is the numerical expression of the images of objects by means of mimicking the functioning of the human visual system and the generation of numerical data for calculations that will be made later. Digital image analysis provides the capability for rapid measurement, which can be made in near-real time, for numerous engineering parameters of materials. Recently, image analysis has been used in geotechnical engineering practices. Grain size distribution and grain shape are the most fundamental properties used to interpret the origin and behaviour of soils. Mechanical sieving has some limitations, e.g., it does not measure the axial dimension of a particle, particle shape is not taken into consideration, and especially for elongated and flat particles a sieve analysis will not yield a reliable measure. In this study the grain size distribution of sands has been determined following image-analysis techniques, using simple apparatus, non-professional cameras and open-code software. The sample is put on a transparent plate that is illuminated with a white backlight. The digital images were acquired with a CCD DSLR camera. The segmentation of the particles is achieved by image thresholding, binary coding and particle labeling. The geometrical measurements of each particle are obtained using an automated pixel-counting technique. Local contacts or limited overlaps were overcome using a watershed split. The same sample was tested by traditional sieve analysis. An image-analysis-based grain size distribution has been compared with a sieve-analysis distribution. The results show that the grain size distribution of the image-based analysis and the sieve analysis are in good agreement.
Ključne besede: image analysis, image processing, grain size, sand
Objavljeno: 18.06.2018; Ogledov: 535; Prenosov: 64
.pdf Celotno besedilo (1,27 MB)
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5.
Effects of the particle shape and size of sands on the hydraulic conductivity
Ali Firat Cabalar, Nurullah Akbulut, 2016, izvirni znanstveni članek

Opis: This study aims to investigate the effects of some physical properties of sands (e.g., size and shape) on the hydraulic conductivity (k). The paper presents the results of an extensive series of experimental investigations performed using sands with different sizes and particle shapes. Three different particle size ranges (0.60- 1.18 mm, 1.18- 2.00 mm, and 0.075- 2.00 mm) of sands (i. Crushed Stone Sand, CSS; ii. Trakya Sand, TS; iii. Narli Sand, NS; iv. Fly Ash Pellets, FAP; v. Leighton Buzzard Sand, LBS) having distinct shapes, including roundness, R, and sphericity, S (Ri=0.15, Si=0.55; Rii=0.43, Sii=0.67; Riii=0.72, Siii=0.79; Riv=0.65, Siv=0.89; Rv=0.78 Sv=0.65) were tested in a constant-head permeability testing apparatus at a relative density (Dr) of about 35% and constant room temperature (20°C). The experimental results showed that the sands having different shapes (R, S) with the same size and gradation characteristics (cc , cu , D10 , D30 , D50 , D60) result in different k values. The scanning electron microscope (SEM) images indicate the physical differences/similarities among the sands used during this investigation. A comparative study of the tests results and the estimated hydraulic conductivity values using empirical equations previously developed for the hydraulic conductivity prediction of soils by certain researchers are presented.
Ključne besede: sand, shape, size, hydraulic conductivity
Objavljeno: 18.06.2018; Ogledov: 435; Prenosov: 43
.pdf Celotno besedilo (587,55 KB)
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6.
Correlation between the point load index, $I_{s(50)}$, and the resistance to unconfined compression in limestone from the comunidad Valenciana, Spain
Manolo Galván, Jorge Preciado, Jose Serón, 2014, izvirni znanstveni članek

Opis: The unconfined compression strength is one of the most important engineering parameters in rock mechanics; it is used to characterize and study the behaviour of solid rocks. A good correlation between the unconfined compression strength test (UCS) and the point load strength (PLS) can be very useful, because it allows for faster and cheaper testing than other methods with the same security to calculate the structures and performances of solid rocks. A preliminary step to implement the correlation is to have a good method to determine the resistance to a point load. This determination is correct if we have a sufficient number of tests on specimens of the same nature, but usually this does not occur, and it is necessary to apply a size-correction factor, F = (De/50)α, with α = 0.45. This paper is based on limestone from Comunidad Valenciana, Spain, because it represents a very high percentage of the rocks. The implementation was conducted over 700 field and laboratory tests, of which 255 are PLT tests, 45 are UCS tests, and the rest are other parameters, like porosity and specific weight, Slake Durability, and ultrasonic velocity.
Ključne besede: resistance to point load, point load strength, Franklin test, size correction factor, unconfined compression
Objavljeno: 14.06.2018; Ogledov: 457; Prenosov: 37
.pdf Celotno besedilo (398,58 KB)
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7.
Mean grain size as a function of spectral amplitude: a new regression law for marine sediment cores
Nelly Zanette, Darinka Battelino, 2017, izvirni znanstveni članek

Opis: Geophysics has been developed in order to supply indicative estimations in soil mechanics like the grain size distribution of finely grained soils as day, silt and fine sands. The paper describes the attempt to characterize porous and saturated marine sediments with a non destructive technique which is the acoustic wave, in order to determine the correlation with geotechnical measurements. The characterization of physical parameters of marine sediments was based on research methods which permit to describe the parameters defining different types of sediment and zones of sedimentation; to determine fundamental parameters that influence the propagation of the acoustic waves in saturated and porous means; to define quick and indicative methods for characterization of physical parameters of analysed means. The acoustic measurements were carried out at SACLANT-NATO of La Spezia (I), where the Vertical Multi Sensor Core Logger (V-MSCL) was used. The results of acoustic tests were compared to the grain size curves of the sediments and the propagation characteristics such as velocity, density, porosity and absorption of experimentally determined data. The analyses are based 011 various mathematical models presented in. literature, in order to predict and to describe physical mechanisms of the wave propagation using a simplification of the sediment structure. The target of the study was to determine a new mathematical law that linked the mean grain size to a directly measurable parameter such as the spectral amplitude, and to offer the possibility to obtain the first indicative value of the sediment mean grain size. The determined exponential law represents an innovative and quick approach to determine a physical characteristic of saturated and porous sediments such as the grain size in a non destructive way based on the spectral analysis of the wave propagation form.
Ključne besede: soil mechanics, marine sediments, finely grained soil, acoustic waves, grain size curve
Objavljeno: 17.05.2018; Ogledov: 542; Prenosov: 52
.pdf Celotno besedilo (437,86 KB)
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8.
An empirical study regarding radical innovation, research and development management, and leadership
Fumihiko Isada, Yuriko Isada, 2017, izvirni znanstveni članek

Opis: The objective of this research is to empirically compare the management that is most suitable for radical innovation with that needed for incremental innovation. The relationship between the results of research and development and management styles was surveyed using a questionnaire. Respondents included research and development leaders in Japanese manufacturing, with special attention given to the differences between radical innovation and incremental innovation. Results verified, in an integrated way, the management and leadership factors, taking into consideration the differences arising from the object under analysis and the environmental factors.
Ključne besede: radical innovation, incremental innovation, research and development management, leadership, size of the firm, technology life cycle, kinds of goods
Objavljeno: 03.11.2017; Ogledov: 624; Prenosov: 294
.pdf Celotno besedilo (245,59 KB)
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9.
The relationship between children's physical fitness and gender, age and environmental factors
Črtomir Matejek, Gregor Starc, 2013, izvirni znanstveni članek

Opis: The main aim of the research was to determine how children’s physical fitness development is related to age, gender, and certain environmental factors at the onset of puberty. The research was carried out on a representative sample of 897 children (47.9 % females and 52.1 % males) aged eleven and fourteen. Twelve tests were used to assess their physical fitness. Based on the duration of the physical activities, the children were divided into four categories: inactive, occasionally active, active and highly active. In the case of paternal education and maternal education, the children were classified into three categories: low, average and high. Considering their school grades in mathematics, the children were divided into three groups: less successful, successful and very successful. In the case of their place of residence, the children were divided into three groups: urban, suburban and rural. A component model of factor analysis was used to identify their basic coordinate system of physical fitness. To solve the problem of the integration of physical fitness into environmental factors, age and gender, a factorial analysis of variance was used. The results show that most of the differences in physical fitness can mainly be explained through age and gender. We can conclude that the significant factors to physical fitness development are growth, development and the maturation rate of individuals, which are predominantly hereditarily determined. Place of residence, physical activity, school grades and parental education have less influence on physical fitness development and serve only as an additional impulse to further stimulate or inhibit the physical development of children.
Ključne besede: physical fitness development, environment, factorial analysis, effect size
Objavljeno: 21.07.2017; Ogledov: 697; Prenosov: 89
.pdf Celotno besedilo (293,84 KB)
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10.
Effect size measurement in functional milk product marketing
Karmen Pažek, Črtomir Rozman, Jernej Turk, Darja Majkovič, Sebjan Hari, Matej Kolenko, Sašo Pamič, Jernej Prišenk, 2011, izvirni znanstveni članek

Opis: The paper presents the application possibility of "Effect size" and Cohen's-d index in the case of introduction of new milk products on the market. The field and online survey were used to establish the potential interest of finalconsumers for new functional food product of dairy company in Slovenia - milk with phytosterols additives. Two techniques possibilities of Cohen-d index were calculated; manual and using the Cohen's-d calculator. Further, the application is focused on two main questions in survey regarding observed problem: 1) Would you buy milk with phytosterols additives, which scientifically proven lowers concentration of cholesterol in blood? 2) Would you pay for it at a higher price? The sample includes 419 surveys, 150 surveyswere conducted on field (control group) and 269 surveys were provided online (experimental group). The Cohenćs-d index (d) results show by using manual and Cohen's-d calculator for both groups "small" effect (d=0.35, i.e. d=0.34 ), and "zero or near zero" effect (d=0.15, i.e.= 0.15) when deciding to buy new milk product.
Ključne besede: effect size, Cohen`s-d index, functional food, milk
Objavljeno: 10.07.2017; Ogledov: 688; Prenosov: 107
.pdf Celotno besedilo (804,43 KB)
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