Wind Speed Parameterization and Turbulence Intermittency in the Roughness Sublayers over Urban Areas: a Wind Tunnel Study

2021 ◽  
Author(s):  
Ziwei Mo ◽  
Chun-Ho Liu
Keyword(s):  
Wind Tunnel ◽  
Analytical Solution ◽  
Urban Areas ◽  
Urban Setting ◽  
Quadrant Analysis ◽  
Law Of The Wall ◽  
Flux Gradient ◽  
Turbulence Intermittency ◽  
The Mean ◽  
Mean Square Errors

<p>The flow in inertial sublayer (ISL) is horizontally homogeneous where the Monin–Obukhov similarity theory (MOST) well describes the flux-gradient relationship.  In contrast, roughness sublayer (RSL) flow is highly inhomogeneous. Its dynamics is influenced by the length scale of individual roughness elements. This study presents an analytical solution to the mean wind profile for both ISL and RSL by adding a new function in the flux-gradient relationship to handle the RSL dynamics. The mean wind speeds measured in the wind tunnel experiments over a range of idealized and real urban geometries are well predicted by the new analytical solution. The root-mean-square errors (RMSE) are reduced over an order of magnitude compared with the conventional logarithmic law of the wall (log-law). Its key parameter, the RSL constant converges asymptotically to μ = 1.7 for urban setting which is different from that (μ = 2.6) for vegetation canopy. The RSL turbulence intermittency is revealed by higher-order moments of velocities, probability density function (PDF), quadrant analysis, and conditional sampling. Ejection Q2 (-u’’, +w”) and sweep Q4 (+u’’, -w”) dominate in both RSL and ISL but with different share. Unlike the ISL, Q2 occurs more frequently (but contributes less to momentum flux) than Q4 in the RSL. It is thus suggested that RSL turbulent transport is driven by occasional, fast motions of accelerating downward flow (Q4) and bulk, slow decelerating upward flow (Q2).</p>

Flow and Turbulence Characteristics in the Roughness Sublayer over Real Urban Morphology of Hong Kong

2020 ◽  
Author(s):  
Ziwei Mo ◽  
Chun-Ho Liu ◽  
Yat-Kiu Ho
Keyword(s):  
Hong Kong ◽  
Wind Tunnel ◽  
Urban Areas ◽  
Air Entrainment ◽  
Urban Morphology ◽  
Pollutant Removal ◽  
Quadrant Analysis ◽  
Vertical Profiles ◽  
Mean Flow ◽  
Law Of The Wall

<p>Mean flow and turbulence in roughness sublayers (RSLs) over urban areas are complicated because of the diversified building configurations (such as size, shape and orientation, etc.). This study investigates the RSL flows over (part of) the real urban morphology of Hong Kong downtown by wind tunnel measurements. The urban models are fabricated by 3D printing using high-resolution digital maps of building morphology and topography. Vertical profiles of mean and turbulent components in three parallel transects are measured by a constant-temperature hot-wire anemometer (CTA). The wind tunnel results reveal that individual (vertical) profiles of streamwise fluctuating velocity u’’, vertical fluctuating velocity w’’ and vertical momentum flux u’’w’’ show noticeable variations in the RSL. It is largely attributed to the wakes and recirculations after the upstream high-rise buildings. A new analytical solution is proposed to predict the mean wind profiles in the RSL as well as the inertial sublayer (ISL) that is more accurate than the conventional logarithmic law of the wall (log-law). The turbulence in the RSL and ISL are examined in terms of quadrant analysis. The ejection Q2 and the sweep Q4 are stronger in the RSL than those in the ISL, collectively improving street-level air entrainment and pollutant removal.</p>

scholarly journals Digit Variability in Carotenoid Scores Obtained with the Veggie Meter: A Pilot Study (P02-001-19)

2019 ◽  
Vol 3 (Supplement_1) ◽  
Author(s):  
Velarie Ansu ◽  
Stephanie Dickinson ◽  
Alyce Fly
Keyword(s):  
Indiana University ◽  
Left Hand ◽  
Funding Sources ◽  
Right Hand ◽  
Period Data ◽  
The Mean ◽  
The Right ◽  
Post Hoc ◽  
Main Effects ◽  
Mean Square Errors

Abstract Objectives To determine which digit and hand have the highest and lowest skin carotenoid scores, to compare inter-and-intra-hand variability of digits, and to determine if results are consistent with another subject. Methods Two subjects’ first(F1), second(F2), third(F3) and fifth(F5) digits on both hands were measured for skin carotenoids with a Veggie Meter, for 3 times on each of 18 days over a 37-day period. Data were subjected to ANOVA in a factorial treatment design to determine main effects for hand (2 levels), digits (4), and days (18) along with interactions. Differences between digits were determined by Tukey's post hoc test. Results There were significant hand x digit, hand x day, digit x day, and hand x digit x day interactions and significant simple main effects for hand, digit, and day (all P < 0.001). Mean square errors were 143.67 and 195.62 for subject A and B, respectively, which were smaller than mean squares for all main effects and interactions. The mean scores ± SD for F1, F2, F3, and F5 digits for the right vs left hands for subject A were F1:357.13 ± 45.97 vs 363.74 ± 46.94, F2:403.17 ± 44.77 vs. 353.20 ± 44.13, F3:406.76 ± 43.10 vs. 357.11 ± 45.13, and F5:374.95 ± 53.00 vs. 377.90 ± 47.38. For subject B, the mean scores ± SD for digits for the right vs left hands were F1:294.72 ± 61.63 vs 280.71 ± 52.48, F2:285.85 ± 66.92 vs 252.67 ± 67.56, F3:268.56 ± 57.03 vs 283.22 ± 45.87, and F5:288.18 ± 34.46 vs 307.54 ± 40.04. The digits on the right hand of both subjects had higher carotenoid scores than those on the left hands, even though subjects had different dominant hands. Subject A had higher skin carotenoid scores on the F3 and F2 digits for the right hand and F5 on the left hand. Subject B had higher skin carotenoid scores on F5 (right) and F1 (left) digits. Conclusions The variability due to hand, digit, and day were all greater than that of the 3 replicates within the digit-day for both volunteers. This indicates that data were not completely random across the readings when remeasuring the same finger. Different fingers displayed higher carotenoid scores for each volunteer. There is a need to conduct a larger study with more subjects and a range of skin tones to determine whether the reliability of measurements among digits of both hands is similar across the population. Funding Sources Indiana University.

scholarly journals Prevalence, pattern and determinants of chronic disease multimorbidity in Nepal: secondary analysis of a national survey

BMJ Open ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. e047665
Author(s):  
Raja Ram Dhungana ◽  
Khem Bahadur Karki ◽  
Bihungum Bista ◽  
Achyut Raj Pandey ◽  
Meghnath Dhimal ◽  
...  
Keyword(s):  
Urban Areas ◽  
Formal Education ◽  
Secondary Analysis ◽  
Density Lipoprotein ◽  
Prevalence Ratio ◽  
Urban Setting ◽  
Chronic Obstructive ◽  
Cluster Sampling ◽  
Obstructive Pulmonary Disease ◽  
Nationally Representative

ObjectivesTo assess the prevalence, pattern and determinants of non-communicable diseases (NCDs) multimorbidity in Nepal.DesignSecondary analysis of the data from the NCD survey 2018, which was conducted between 2016 and 2018.SettingThe data belong to the nationally representative survey, that selected the study samples from throughout Nepal using multistage cluster sampling.Participants8931 participants aged 20 years and older were included in the study.Primary outcomesNCD multimorbidity (occurrence of two or more chronic conditions including hypertension, diabetes, chronic obstructive pulmonary disease, chronic kidney disease, coronary artery disease and cancer). Descriptive statistics, prevalence ratio and odds ratio were computed to assess pattern and determinants of multimorbidity.ResultsMean (SD) age was 46.7 years (14.9 years). The majority of the participants were women (57.8%), without formal education (53.4%) and from urban areas (51.5%). Multimorbidity was present in 13.96% (95% CI: 12.9% to 15.1%). Hypertension and diabetes coexisted in 5.7%. Age, alcohol consumption, body mass index, non-high-density lipoprotein (non-HDL) level and rural–urban setting were significantly associated with multimorbidity.ConclusionMultimorbidity was prevalent in particular groups or geographical areas in Nepal suggesting a need for coordinated and integrated NCD care approach for the management of multiplicative co-comorbid conditions.

scholarly journals Country-level determinants of the severity of the first global wave of the COVID-19 pandemic: an ecological study

BMJ Open ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. e042034
Author(s):  
Tiberiu A Pana ◽  
Sohinee Bhattacharya ◽  
David T Gamble ◽  
Zahra Pasdar ◽  
Weronika A Szlachetka ◽  
...  
Keyword(s):  
Mortality Rate ◽  
Vaccination Coverage ◽  
Urban Areas ◽  
Ecological Study ◽  
Environmental Parameters ◽  
The Philippines ◽  
International Travel ◽  
Bcg Vaccination ◽  
Country Level ◽  
The Mean

ObjectiveWe aimed to identify the country-level determinants of the severity of the first wave of the COVID-19 pandemic.DesignEcological study of publicly available data. Countries reporting >25 COVID-19 related deaths until 8 June 2020 were included. The outcome was log mean mortality rate from COVID-19, an estimate of the country-level daily increase in reported deaths during the ascending phase of the epidemic curve. Potential determinants assessed were most recently published demographic parameters (population and population density, percentage population living in urban areas, population >65 years, average body mass index and smoking prevalence); economic parameters (gross domestic product per capita); environmental parameters (pollution levels and mean temperature (January–May); comorbidities (prevalence of diabetes, hypertension and cancer); health system parameters (WHO Health Index and hospital beds per 10 000 population); international arrivals; the stringency index, as a measure of country-level response to COVID-19; BCG vaccination coverage; UV radiation exposure; and testing capacity. Multivariable linear regression was used to analyse the data.Primary outcomeCountry-level mean mortality rate: the mean slope of the COVID-19 mortality curve during its ascending phase.ParticipantsThirty-seven countries were included: Algeria, Argentina, Austria, Belgium, Brazil, Canada, Chile, Colombia, the Dominican Republic, Ecuador, Egypt, Finland, France, Germany, Hungary, India, Indonesia, Ireland, Italy, Japan, Mexico, the Netherlands, Peru, the Philippines, Poland, Portugal, Romania, the Russian Federation, Saudi Arabia, South Africa, Spain, Sweden, Switzerland, Turkey, Ukraine, the UK and the USA.ResultsOf all country-level determinants included in the multivariable model, total number of international arrivals (beta 0.033 (95% CI 0.012 to 0.054)) and BCG vaccination coverage (−0.018 (95% CI −0.034 to –0.002)), were significantly associated with the natural logarithm of the mean death rate.ConclusionsInternational travel was directly associated with the mortality slope and thus potentially the spread of COVID-19. Very early restrictions on international travel should be considered to control COVID-19 outbreaks and prevent related deaths.

scholarly journals Salt intake and blood pressure in Iranian children and adolescents: a population-based study

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Mohammad Hassan Emamian ◽  
Hossein Ebrahimi ◽  
Hassan Hashemi ◽  
Akbar Fotouhi
Keyword(s):  
Blood Pressure ◽  
Rural Areas ◽  
Urban Areas ◽  
Salt Intake ◽  
Daily Intake ◽  
Population Based ◽  
World Health ◽  
Second Phase ◽  
Salt Consumption ◽  
The Mean

Abstract Background Previous studies have reported a high prevalence of hypertension in Iranian students, especially in rural areas. The aim of this study was to investigate the daily intake of salt in students and its association with high blood pressure. Methods A random sub-sample was selected from the participants of the second phase of Shahroud schoolchildren eye cohort study and then a random urine sample was tested for sodium, potassium and creatinine. Urine electrolyte esexcretion and daily salt intake were calculated by Tanaka et al.’s formula. Results Among 1455 participants (including 230 participants from rural area and 472 girls), the mean age was 12.9 ± 1.7 year and the mean daily salt intake was 9.7 ± 2.6 g (95% CI 9.5–9.8). The mean salt consumption in rural areas [10.8 (95% CI 10.4–11.2)] was higher than urban areas [9.4 (95% CI 9.3–9.6)], in people with hypertension [10.8 (95% CI 10.3–11.3)] was more than people with normal blood pressure [9.4 (95% CI 9.3–9.6)], and in boys [9.8 (95% CI 9.7–10.0)] was more than girls [9.3 (95% CI 9.1–9.6)]. Higher age, BMI z-score, male sex and rural life, were associated with increased daily salt intake. Increased salt intake was associated with increased systolic and diastolic blood pressure. Conclusion Daily salt intake in Iranian adolescents was about 2 times the recommended amount of the World Health Organization, was higher in rural areas and was associated with blood pressure. Reducing salt intake should be considered as an important intervention, especially in rural areas.

scholarly journals The Awareness of and Input into Cultural Heritage Preservation by Urban Planners and Other Municipal Actors in Light of Climate Change

Atmosphere ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 726
Author(s):  
Paul Carroll ◽  
Eeva Aarrevaara
Keyword(s):  
Climate Change ◽  
Cultural Heritage ◽  
Urban Areas ◽  
Climate Change Impacts ◽  
Town Planning ◽  
Urban Setting ◽  
Heritage Preservation ◽  
Climate Conditions ◽  
The Future ◽  
Cultural Heritage Preservation

Future climate conditions need to be considered in planning for urban areas. As well as considering how new structures would best endure in the future, it is important to take into account factors that contribute to the degradation of cultural heritage buildings in the urban setting. Climate change can cause an increase in structural degradation. In this paper, a review of both what these factors are and how they are addressed by urban planners is presented. A series of inquiries into the topic was carried out on town planning personnel and those involved in cultural heritage preservation in several towns and cities in Finland and in a small number of other European countries. The target group members were asked about observed climate change impacts on cultural heritage, about present steps being taken to protect urban cultural heritage, and also their views were obtained on how climate change impacts will be emphasised in the future in this regard. The results of the inquiry demonstrate that climate change is still considered only in a limited way in urban planning, and more interaction between different bodies, both planning and heritage authorities, as well as current research on climate change impacts, is needed in the field.

scholarly journals A hospital-based study on clinical data, demographic data and visual function of keratoconus patients in Central China

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kaili Yang ◽  
Liyan Xu ◽  
Qi Fan ◽  
Yuwei Gu ◽  
Bo Zhang ◽  
...  
Keyword(s):  
Clinical Data ◽  
Rural Areas ◽  
Visual Function ◽  
Urban Areas ◽  
Demographic Data ◽  
Corneal Thickness ◽  
Positive Family History ◽  
Education Level ◽  
Central China ◽  
The Mean

AbstractChina is a populous country but lacks epidemiological data on keratoconus (KC). The present study aimed to investigate the clinical data, demographic data, and visual function (VF) data of KC patients in Central China. A total of 524 KC eyes in 307 KC patients (217 bilateral and 90 unilateral) from Henan Eye Hospital were included in the current study. Demographic and VF data were assessed with questionnaires administered by well-trained staff during face-to-face interviews. Visual acuity value was examined by a qualified optometrist, and the clinical data were measured by professional clinicians. The distributions of sex, residence and education level of KC patients were compared by Chi-square tests, and the ratios of people wearing glasses and rigid gas permeable (RGP) lenses were compared by McNemar tests. General linear models/Chi-squared tests were used to compare the clinical and demographic data according to KC severity. Spearman’s correlation analysis was used to test the associations between the data and KC severity. The mean age at diagnosis was 20.98 ± 6.06 years, and males had a higher ratio of KC than females (P < 0.001). Patients in rural areas had a higher rate of KC than those in urban areas (P = 0.039), and the proportion of KC patients with a higher education level (above high school) was high (P < 0.001). A total of 68.40% of the patients reported eye rubbing and 3.52% had a positive family history. The percentage of people wearing glasses was higher than that of patients wearing RGP lenses (P < 0.001). The total VF score of KC patients was 69.35 ± 15.25. The thinnest corneal thickness (TCT) and stiffness parameter at the first applanation (SP-A1) values were inversely correlated with KC severity (P < 0.05). The mean, steep, and max keratometry (Km, Ks and Kmax) values, the RGP lens use and keratoplasty were positively correlated with KC severity (all P < 0.05). The total VF score of the eye with better VA decreased as the severity increased (r = − 0.21, P = 0.002). The present study comprehensively describes various associated features of KC patients from a tertiary hospital in Central China, providing a reference for understanding the characteristics of KC patients in China.

Wind tunnel investigation on the retention of air pollutants in three-dimensional recirculation zones in urban areas

2007 ◽  
Vol 41 (23) ◽  
pp. 4949-4961 ◽  
Author(s):  
Marcos Sebastião de Paula Gomes ◽  
André Augusto Isnard ◽  
José Maurício do Carmo Pinto
Keyword(s):  
Wind Tunnel ◽  
Urban Areas ◽  
Air Pollutants ◽  
Three Dimensional ◽  
Recirculation Zones

Wingbeat frequency of barn swallows and house martins: a comparison between free flight and wind tunnel experiments

2002 ◽  
Vol 205 (16) ◽  
pp. 2461-2467 ◽  
Author(s):  
Felix Liechti ◽  
Lukas Bruderer
Keyword(s):  
Wind Tunnel ◽  
Single Pulse ◽  
Free Flight ◽  
Wind Tunnel Experiments ◽  
Wingbeat Frequency ◽  
Flight Costs ◽  
Radar Echo ◽  
The Mean ◽  
Barn Swallows ◽  
Air Speed

SUMMARYThe flight paths and wingbeat patterns of 39 barn swallows (Hirundo rustica) and 26 house martins (Delichon urbica) were recorded by tracking radar during the spring migration. Depending mostly on flight angle,hirundines performed anything from continuous flapping flight during climbing to single pulse-like wing beats during descent. Unlike most other passerines,hirundines rarely showed regular flapping and rest phases, allowing them to be distinguished from other bird migrants by radar echo signatures. Effective wingbeat frequency (Feff) was calculated as the mean number of wing beats per second, including non-flapping phases. Under comparable flight conditions, Feff was higher in house martins than in barn swallows. Within species, Feff values were higher during climbing and slow flying than during descent. Of the variance in Feff, 71 % could be explained by climb rate,air speed and species; similar results were obtained in the wind tunnel. Under comparable flight conditions, barn swallows and house martins in free flight had significantly lower values of Feff than individuals in wind tunnel experiments (by 40 % and 32 %, respectively). This difference may at least partly be due to the shorter wings of the juveniles tested in the wind tunnel during autumn. However, it seems unlikely that this can account for all of the large difference. It is suggested that wind tunnel experiments might overestimate birds' flight costs compared with free flight.

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