Wake Analysis of an Aerodynamically Optimized Boxprop High-Speed Propeller

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Alexandre Capitao Patrao ◽  
Tomas Grönstedt ◽  
Anders Lundbladh ◽  
Gonzalo Montero Villar
Keyword(s):  
High Speed ◽  
Tip Vortex ◽  
Lower Amount ◽  
Optimized Design ◽  
Aerodynamic Optimization ◽  
Vortex Strength ◽  
Percentage Point Increase ◽  
Aerodynamic Loading ◽  
Point Increase ◽  
Propeller Blades

The Boxprop is a novel, double-bladed, tip-joined propeller for high-speed flight. The concept draws inspiration from the box wing concept and could potentially decrease tip vortex strength compared with conventional propeller blades. Early Boxprop designs experienced significant amounts of blade interference. By performing a wake analysis and quantifying the various losses of the flow, it could be seen that these Boxprop designs produced 45% more swirl than a conventional reference blade. The reason for this was the proximity of the Boxprop blade halves to each other, which prevented the Boxprop from achieving the required aerodynamic loading on the outer parts of the blade. This paper presents an aerodynamic optimization of a 6-bladed Boxprop aiming at maximizing efficiency and thrust at cruise. A geometric parametrization has been adopted which decreases interference by allowing the blade halves to be swept in opposite directions. Compared with an earlier equal-thrust Boxprop design, the optimized design features a 7% percentage point increase in propeller efficiency and a lower amount of swirl and entropy generation. A vortex-like structure has also appeared downstream of the optimized Boxprop, but with two key differences relative to conventional propellers. (1) Its formation differs from a traditional tip vortex and (2) it is 46% weaker than the tip vortex of an optimized 12-bladed conventional propeller.

Multi-Objective and Multi-Point Aerodynamic Optimization of Transonic Fan Blades

2014 ◽  
Author(s):  
Maryam Khelghatibana ◽  
Jean-Yves Trépanier ◽  
Christophe Tribes ◽  
Jason Nichols
Keyword(s):  
High Speed ◽  
Stokes Equations ◽  
Pressure Ratio ◽  
Operating Conditions ◽  
Optimized Design ◽  
Aerodynamic Optimization ◽  
Stall Margin ◽  
Choked Flow ◽  
Multi Objective ◽  
Transonic Fan

A multi-objective and multi-point optimization methodology is developed for aerodynamic design of transonic fan blades. The optimization method aims to increase design efficiency, near stall efficiency and stall margin while maintaining the required design pressure ratio and high speed choke margin. Numerical analyses are performed by solving three-dimensional Reynolds-Averaged Navier-Stokes equations combined with shear stress turbulence model. A multi-level blade parameterization is employed to modify the blade geometry. The proposed method is applied to redesign NASA rotor 67. First, an optimization case with considering two operating conditions at peak efficiency and near stall is performed to demonstrate the relation between near stall efficiency and stall margin. An investigation on Pareto optimal solutions of this optimization shows that the stall margin is increased with improving near stall efficiency. Then, in order to maintain the required choke margin, an operating point at high speed choked flow is added to the optimization process. A final optimized design is selected by considering the interaction of design requirements at all three operating points. The new design presents higher efficiency and stall margin without any reduction in the chocking mass flow rate.

scholarly journals The Effects of Aerial Spraying of Coca Crops on Child Labor, School Attendance, and Educational Lag in Colombia, 2008-2012

2020 ◽  
Vol 6 (1) ◽  
pp. 84
Author(s):  
Claudia Rodriguez
Keyword(s):  
Child Labor ◽  
High Speed ◽  
School Attendance ◽  
War On Drugs ◽  
Drop Out ◽  
Percentage Point Increase ◽  
Point Increase ◽  
Colombian Government ◽  
Aerial Spraying ◽  
Older Siblings

Since 1999, one of the main strategies the Colombian government has used to mitigate coca cultivation is to spray the crops with herbicide, which is carried out from airplanes. This paper evaluates the consequences of this strategy for rural households in areas where coca is cultivated, specifically the effects of aerial spraying on child labor and education. Since the areas where spraying takes place are fundamentally different from those where it does not, I use a two-stage least squares model, instrumenting for aerial eradication with the number of days high-speed winds in the municipality made spraying difficult. These were days in which the wind was one standard deviation above the municipality's monthly average. This corrects for possible sources of endogeneity due to selection bias. The results of this study show that aerial spraying was associated with a one percentage point increase in the likelihood that children ages 12-17 would work instead of going to school. Crop spraying was further associated with a 0.15 percentage point increase in the probability that older siblings in families living in a coca-growing area would fall behind in school, and a five percentage point increase in the probability that younger siblings would drop out of school. Thus, the findings of this research, based on data that cover the period from 2008 to 2012, suggest that the war on drugs has the potential to generate new barriers to educational access for children who live in areas where aerial spraying occurs.

Broadband in the Labor Market

ILR Review ◽  
2016 ◽  
Vol 70 (2) ◽  
pp. 451-482 ◽  
Author(s):  
Lisa J. Dettling
Keyword(s):  
High Speed ◽  
Internet Use ◽  
Single Women ◽  
Married Women ◽  
Broadband Internet ◽  
Percentage Point Increase ◽  
Family Balance ◽  
Point Increase ◽  
State Variation ◽  
Work Family

The author investigates how high-speed home Internet use has affected labor supply. Using an instrumental variables strategy that exploits cross-state variation in supply-side constraints to residential broadband Internet access, she finds that exogenously determined high-speed Internet use leads to a 4.1 percentage point increase in labor force participation for married women. No corresponding effect is found for single women or men. Among married women, the largest increases in participation are found among college-educated women with children. Supplemental analyses suggest that Internet use for telework and saving time in home production explains the increase in participation. The results suggest that home Internet facilitates work-family balance.

The Effect of Taxation and Corruption on Firm Growth: An Empirical Investigation for Vietnam

2016 ◽  
pp. 5-29
Author(s):  
Bich Le Thi Ngoc
Keyword(s):  
International Development ◽  
Firm Growth ◽  
Empirical Investigation ◽  
Manufacturing Firms ◽  
Economic Management ◽  
Tax Rate ◽  
Percentage Point Increase ◽  
Percentage Points ◽  
Point Increase ◽  
The Impact

The aim of this study is to analyze empirically the impact of taxation and corruption on the growth of manufacturing firms in Vietnam. The study employed pooled OLS estimation and then instrument variables with fixed effect for the panel data of 1377 firms in Vietnam from 2005 to 2011. These data were obtained from the survey of the Central Institute for Economic Management and the Danish International Development Agency. The results show that both taxation and corruption are negatively associated with firm growth measured by firm sales adjusted according to the GDP deflator. A one-percentage point increase in the bribery rate is linked with a reduction of 16,883 percentage points in firm revenue, over four and a half times bigger than the effect of a one-percentage point increase in the tax rate. From the findings of this research, the author recommends the Vietnam government to lessen taxation on firms and that there should be an urgent revolution in anti-corruption policies as well as bureaucratic improvement in Vietnam.

scholarly journals African American Unemployment and the Disparity in Periviable Births

2021 ◽  
Author(s):  
Ralph Catalano ◽  
Deborah Karasek ◽  
Tim Bruckner ◽  
Joan A. Casey ◽  
Katherine Saxton ◽  
...  
Keyword(s):  
African American ◽  
African American Women ◽  
Unemployment Rate ◽  
Racial Disparity ◽  
Live Births ◽  
Percentage Point Increase ◽  
Point Increase ◽  
The Us ◽  
Race Ethnicity ◽  
Hispanic White

AbstractPeriviable infants (i.e., born before 26 complete weeks of gestation) represent fewer than .5% of births in the US but account for 40% of infant mortality and 20% of billed hospital obstetric costs. African American women contribute about 14% of live births in the US, but these include nearly a third of the country’s periviable births. Consistent with theory and with periviable births among other race/ethnicity groups, males predominate among African American periviable births in stressed populations. We test the hypothesis that the disparity in periviable male births among African American and non-Hispanic white populations responds to the African American unemployment rate because that indicator not only traces, but also contributes to, the prevalence of stress in the population. We use time-series methods that control for autocorrelation including secular trends, seasonality, and the tendency to remain elevated or depressed after high or low values. The racial disparity in male periviable birth increases by 4.45% for each percentage point increase in the unemployment rate of African Americans above its expected value. We infer that unemployment—a population stressor over which our institutions exercise considerable control—affects the disparity between African American and non-Hispanic white periviable births in the US.

Health Insurance Status as a Predictor of Mode of Colon Cancer Detection but Not Stage at Diagnosis: Implications for Early Detection

2021 ◽  
pp. 003335492199917
Author(s):  
Lindsey A. Jones ◽  
Katherine C. Brewer ◽  
Leslie R. Carnahan ◽  
Jennifer A. Parsons ◽  
Blase N. Polite ◽  
...  
Keyword(s):  
Colon Cancer ◽  
Health Insurance ◽  
Early Detection ◽  
Late Stage ◽  
Early Stage ◽  
Insurance Status ◽  
Stage At Diagnosis ◽  
Health Insurance Status ◽  
Percentage Point Increase ◽  
Point Increase

Objective For colon cancer patients, one goal of health insurance is to improve access to screening that leads to early detection, early-stage diagnosis, and polyp removal, all of which results in easier treatment and better outcomes. We examined associations among health insurance status, mode of detection (screen detection vs symptomatic presentation), and stage at diagnosis (early vs late) in a diverse sample of patients recently diagnosed with colon cancer from the Chicago metropolitan area. Methods Data came from the Colon Cancer Patterns of Care in Chicago study of racial and socioeconomic disparities in colon cancer screening, diagnosis, and care. We collected data from the medical records of non-Hispanic Black and non-Hispanic White patients aged ≥50 and diagnosed with colon cancer from October 2010 through January 2014 (N = 348). We used logistic regression with marginal standardization to model associations between health insurance status and study outcomes. Results After adjusting for age, race, sex, and socioeconomic status, being continuously insured 5 years before diagnosis and through diagnosis was associated with a 20 (95% CI, 8-33) percentage-point increase in prevalence of screen detection. Screen detection in turn was associated with a 15 (95% CI, 3-27) percentage-point increase in early-stage diagnosis; however, nearly half (47%; n = 54) of the 114 screen-detected patients were still diagnosed at late stage (stage 3 or 4). Health insurance status was not associated with earlier stage at diagnosis. Conclusions For health insurance to effectively shift stage at diagnosis, stronger associations are needed between health insurance and screening-related detection; between screening-related detection and early stage at diagnosis; or both. Findings also highlight the need to better understand factors contributing to late-stage colon cancer diagnosis despite screen detection.

Aligning Medicaid and Medicare Advantage Managed Care Plans for Dual-Eligible Beneficiaries

2021 ◽  
pp. 107755872110189
Author(s):  
Laura M. Keohane ◽  
Zilu Zhou ◽  
David G. Stevenson
Keyword(s):  
Nursing Home ◽  
Managed Care ◽  
Prescription Drugs ◽  
Service Use ◽  
Medicare Advantage ◽  
Percentage Point Increase ◽  
Care Plans ◽  
Point Increase ◽  
Dual Eligible ◽  
Home Users

To coordinate Medicare and Medicaid benefits, multiple states are creating opportunities for dual-eligible beneficiaries to join Medicare Advantage Dual-Eligible Special Needs Plans (D-SNPs) and Medicaid plans operated by the same insurer. Tennessee implemented this approach by requiring insurers who offered Medicaid plans to also offer a D-SNP by 2015. Tennessee’s aligned D-SNP participation increased from 7% to 24% of dual-eligible beneficiaries aged 65 years and above between 2011 and 2017. Within a county, a 10-percentage-point increase in aligned D-SNP participation was associated with 0.3 fewer inpatient admissions ( p = .048), 13.9 fewer prescription drugs per month ( p = .048), and 0.3 fewer nursing home users ( p = .06) per 100 dual-eligible beneficiaries aged 65 years and older. Increased aligned plan participation was associated with 0.2 more inpatient admissions ( p = .004) per 100 dual-eligible beneficiaries younger than 65 years. For some dual-eligible beneficiaries, increasing Medicare and Medicaid managed plan alignment has the potential to promote more efficient service use.

scholarly journals Mendelian randomization analysis of arsenic metabolism and pulmonary function within the Hispanic Community Health Study/Study of Latinos

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Molly Scannell Bryan ◽  
Tamar Sofer ◽  
Majid Afshar ◽  
Yasmin Mossavar-Rahmani ◽  
H. Dean Hosgood ◽  
...  
Keyword(s):  
Pulmonary Function ◽  
Mendelian Randomization ◽  
Smoking History ◽  
Health Study ◽  
Arsenic Metabolism ◽  
Percentage Point Increase ◽  
Point Increase ◽  
Increased Risk ◽  
Genotype Information ◽  
Rice Consumption

AbstractArsenic exposure has been linked to poor pulmonary function, and inefficient arsenic metabolizers may be at increased risk. Dietary rice has recently been identified as a possible substantial route of exposure to arsenic, and it remains unknown whether it can provide a sufficient level of exposure to affect pulmonary function in inefficient metabolizers. Within 12,609 participants of HCHS/SOL, asthma diagnoses and spirometry-based measures of pulmonary function were assessed, and rice consumption was inferred from grain intake via a food frequency questionnaire. After stratifying by smoking history, the relationship between arsenic metabolism efficiency [percentages of inorganic arsenic (%iAs), monomethylarsenate (%MMA), and dimethylarsinate (%DMA) species in urine] and the measures of pulmonary function were estimated in a two-sample Mendelian randomization approach (genotype information from an Illumina HumanOmni2.5-8v1-1 array), focusing on participants with high inferred rice consumption. Among never-smoking high inferred consumers of rice (n = 1395), inefficient metabolism was associated with past asthma diagnosis and forced vital capacity below the lower limit of normal (LLN) (OR 1.40, p = 0.0212 and OR 1.42, p = 0.0072, respectively, for each percentage-point increase in %iAs; OR 1.26, p = 0.0240 and OR 1.24, p = 0.0193 for %MMA; OR 0.87, p = 0.0209 and OR 0.87, p = 0.0123 for the marker of efficient metabolism, %DMA). Among ever-smoking high inferred consumers of rice (n = 1127), inefficient metabolism was associated with peak expiratory flow below LLN (OR 1.54, p = 0.0108/percentage-point increase in %iAs, OR 1.37, p = 0.0097 for %MMA, and OR 0.83, p = 0.0093 for %DMA). Less efficient arsenic metabolism was associated with indicators of pulmonary dysfunction among those with high inferred rice consumption, suggesting that reductions in dietary arsenic could improve respiratory health.

scholarly journals Planning prompts to promote uptake of HIV services among men: a randomised trial in rural Uganda

2020 ◽  
Vol 5 (11) ◽  
pp. e003390
Author(s):  
Nolan M Kavanagh ◽  
Elisabeth M Schaffer ◽  
Alex Ndyabakira ◽  
Kara Marson ◽  
Diane V Havlir ◽  
...  
Keyword(s):  
Hiv Testing ◽  
Community Health ◽  
Control Group ◽  
Health Campaign ◽  
Percentage Point Increase ◽  
Percentage Points ◽  
Point Increase ◽  
Cost Planning ◽  
Testing Uptake ◽  
The Impact

IntroductionInterventions informed by behavioural economics, such as planning prompts, have the potential to increase HIV testing at minimal or no cost. Planning prompts have not been previously evaluated for HIV testing uptake. We conducted a randomised clinical trial to evaluate the effectiveness of low-cost planning prompts to promote HIV testing among men.MethodsWe randomised adult men in rural Ugandan parishes to receive a calendar planning prompt that gave them the opportunity to make a plan to get tested for HIV at health campaigns held in their communities. Participants received either a calendar showing the dates when the community health campaign would be held (control group) or a calendar showing the dates and prompting them to select a date and time when they planned to attend (planning prompt group). Participants were not required to select a date and time or to share their selection with study staff. The primary outcome was HIV testing uptake at the community health campaign.ResultsAmong 2362 participants, 1796 (76%) participants tested for HIV. Men who received a planning prompt were 2.2 percentage points more likely to test than the control group, although the difference was not statistically significant (77.1% vs 74.9%; 95% CI –1.2 to 5.7 percentage points, p=0.20). The planning prompt was more effective among men enrolled ≤40 days before the campaigns (3.6 percentage-point increase in testing; 95% CI –2.9 to 10.1, p=0.27) than among men enrolled >40 days before the campaigns (1.8 percentage-point increase; 95% CI –2.3 to 5.8, p=0.39), although the effects within the subgroups were not significant.ConclusionThese findings suggest that planning prompts may be an effective behavioural intervention to promote HIV testing at minimal or no cost. Large-scale studies should further assess the impact and cost-effectiveness of such interventions.

scholarly journals Spatial–temporal trends in forced migrant mortality, 2014–2018

2020 ◽  
Vol 5 (10) ◽  
pp. e002885
Author(s):  
Danielle N Poole ◽  
Bethany Hedt-Gauthier ◽  
Till Bärnighausen ◽  
Stéphane Verguet ◽  
Marcia C Castro
Keyword(s):  
Temporal Trends ◽  
Forced Migration ◽  
Global Scale ◽  
International Organization ◽  
Temporal Heterogeneity ◽  
Percentage Point Increase ◽  
Humanitarian Response ◽  
Risk Of Mortality ◽  
Point Increase ◽  
Time Periods

IntroductionThe identification of spatial–temporal clusters of forced migrant mortality is urgently needed to inform preventative policies and humanitarian response. As a first step towards understanding the geography of forced migrant mortality, this study investigates spatial–temporal patterns in death at a global scale.MethodsWe used information on the location and dates of forced migrant deaths reported in the International Organization for Migration’s Missing Migrant Project from 2014 to 2018. Kulldorff’s spatial–temporal and seasonal scans were used to detect spatial–temporal and temporal heterogeneity in mortality.ResultsA total of 16 314 deaths were reported during the study period. A preponderance of deaths occurred at sea each year (range 26%–54% across 5 years). Twelve spatial–temporal clusters of forced migrant mortality were detected by maximum likelihood testing. Annually, the period of August–October was associated with a 40-percentage-point increase in the risk of mortality, relative to other time periods.ConclusionsDeath during forced migration occurs close to national borders and during periods of intense conflict. This evidence may inform the design of policies and targeting of interventions to prevent forced migration-related deaths.

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