Impact of spanwise non-uniform discrete gusts on civil aircraft loads

2019 ◽  
Vol 123 (1259) ◽  
pp. 93-120 ◽  
Author(s):  
M. Lone ◽  
G. Dussart
Keyword(s):  
Aircraft Design ◽  
Past Research ◽  
Maximum Load ◽  
Lower Envelope ◽  
Load Factor ◽  
Test Case ◽  
Research Experience ◽  
Aspect Ratios ◽  
Load Factors ◽  
The Impact

ABSTRACTThe drive for increasing flight efficiency is resulting in wing designs that are of higher aspect ratios, lower in weight, increased wingspans and, consequently, require greater attention in the disciplines of aeroelastics and loads. This trend in aircraft design, along with past research experience with flexible aircraft, motivate a review of assumptions in gust models; especially, that of the gust maintaining a uniform spanwise profile. In this paper, the authors investigate the use of spanwise varying 1−cos gust models for loads prediction using a non-linear aeroelastic model of a conventional large transport aircraft. The comparison between a test case using conventional uni-dimensional approach and another, using multidimensional gusts, illustrates the impact of stepping away from traditional discrete tuned gust processes and adding a spanwise varying gust component. A methodology for processing and analysing the loads data arising due to the added dimension is also developed and both envelope and correlated loads are considered. Gust characteristics and resulting load factor are, respectively, considered for comparison between the two models, as both metrics define realistic gust encounters. In this case, it has been shown that spanwise variation of gust profiles leads to lower envelope loads if viewed in terms of conventional gust gradients. However, higher envelope loads are found if the maximum load factors are matched.

Environmental Load Factors for Offshore Structures

1999 ◽  
Vol 121 (4) ◽  
pp. 261-267
Author(s):  
H. P. Hong ◽  
M. A. Nessim ◽  
I. J. Jordaan
Keyword(s):  
Model Uncertainty ◽  
Offshore Structures ◽  
Specific Model ◽  
Load Factor ◽  
Environmental Load ◽  
Load Effect ◽  
Environmental Loads ◽  
Load Factors ◽  
Environmental Process ◽  
The Impact

An analysis of the impact of model uncertainties on the design factors for environmental loads on offshore structures was carried out. Considering uncertainties in environmental processes, the load effect models and the member resistance, an approach was developed that gives explicit consideration to model uncertainty in codified design. For frequent environmental load effects, a two-factor approach was developed that defines the overall load factor as the product of two components: a basic factor accounting for uncertainty in the environmental process and a separate factor accounting for model uncertainty. The overall load factor is to be applied to the specified load, which is defined as the load corresponding to the environmental process value associated with a specified return period. This load can be calculated from the environmental process without considering model uncertainty. The model uncertainty factor was defined as a linear function of the mean and the standard deviation of the model uncertainty parameter. It can be estimated based on a specific model and reliability analysis. This two-factor approach has two advantages: (a) it allows for reductions in the load factor if conservative or more accurate models are used; and (b) it eliminates the need for the designer to consider model uncertainty in estimating the specified load. The approach was used to develop a set of load factors for environmental loads on offshore structures. These factors were calibrated to produce reliability levels consistent with those implied by the load factors in CSA-S471.

scholarly journals THE FUTURE OF PASSENGER AIR TRANSPORT – VERY LARGE AIRCRAFT AND OUT KEY HUMAN FACTORS AFFECTING THE OPERATION AND SAFETY OF PASSENGER AIR TRANSPORT

2017 ◽  
Vol 12 ◽  
pp. 104
Author(s):  
Petra Skolilova
Keyword(s):  
Human Factors ◽  
Human Error ◽  
Operating Cost ◽  
Aircraft Design ◽  
Air Transport ◽  
Final Decision ◽  
Factors Affecting ◽  
Fuel Burn ◽  
The Future ◽  
The Impact

The article outlines some human factors affecting the operation and safety of passenger air transport given the massive increase in the use of the VLA. Decrease of the impact of the CO2 world emissions is one of the key goals for the new aircraft design. The main wave is going to reduce the burned fuel. Therefore, the eco-efficiency engines combined with reasonable economic operation of the aircraft are very important from an aviation perspective. The prediction for the year 2030 says that about 90% of people, which will use long-haul flights to fly between big cities. So, the A380 was designed exactly for this time period, with a focus on the right capacity, right operating cost and right fuel burn per seat. There is no aircraft today with better fuel burn combined with eco-efficiency per seat, than the A380. The very large aircrafts (VLAs) are the future of the commercial passenger aviation. Operating cost versus safety or CO2 emissions versus increasing automation inside the new generation aircraft. Almost 80% of the world aircraft accidents are caused by human error based on wrong action, reaction or final decision of pilots, the catastrophic failures of aircraft systems, or air traffic control errors are not so frequent. So, we are at the beginning of a new age in passenger aviation and the role of the human factor is more important than ever.

“I think Canadians look like all sorts of people”: ethnicity, political leadership, and the case of Jagmeet Singh

2021 ◽  
pp. 1-32
Author(s):  
Joanie Bouchard
Keyword(s):  
Political Behavior ◽  
Political Leadership ◽  
Past Research ◽  
Vote Choice ◽  
Party Leader ◽  
Political Leaders ◽  
Party Leaders ◽  
Sociodemographic Profile ◽  
The Impact ◽  
Voting Intentions

Abstract Research into the impact of a politician's sociodemographic profile on vote choice in Westminster-style systems has been hindered by the relative sociodemographic homogeneity of party leaders. Past research has focused mainly on the evaluation of local candidates in the American context, but given that elections in plurality systems are far less candidate-oriented , the evaluation of local candidates tells us little about the prevalence of affinity or discrimination in other contexts. This article investigates the effect of political leaders' ethnicity on political behavior by looking at the case of Jagmeet Singh in Canada, the first federal party leader of color in the country's history. While the literature has shown that the gender of leaders in Canada can matter, little is known about the attitudes of Canadians toward party leaders of color specifically. We are interested in the evaluations of Singh and his party, as well as the shifts in voting intentions between elections in 2015 and 2019. We uncover affinity-based behaviors from individuals who identify as Sikh, as well as a negative reception of Singh's candidacy in Quebec.

scholarly journals Meaning Matters: Self-Perceived Meaning in Life, Its Predictors and Psychological Stressors Associated with the COVID-19 Pandemic

2021 ◽  
Vol 11 (4) ◽  
pp. 50
Author(s):  
Ashley Humphrey ◽  
Olivia Vari
Keyword(s):  
Life Events ◽  
Meaning In Life ◽  
Protective Factor ◽  
Negative Life Events ◽  
Past Research ◽  
Coping Resources ◽  
Life Meaning ◽  
Life Orientation ◽  
Psychological Stressors ◽  
The Impact

Past research has found that a perceived meaning in life can act as a protective factor against adverse mental health symptomology, while also providing coping resources to buffer against the impact of negative life events. The current research investigated how the impact of self-perceived meaning in life as well as its predictors interact with stressors and worry related to the COVID-19 pandemic. We collected survey based data (n = 260) from Australian participants during the pandemic, measuring their meaning in life, orientation to differing life goals and COVID-19 related stressors via the impact of events scale. We found that meaning in life predicted less stress and worry associated with COVID-19. We also found that intrinsic based aspirations related positively to meaning in life within this context whereas extrinsic based goals related negatively to it, although these aspirations were not significant in reducing the stressors associated with COVID-19. These results reinforce past findings that meaning in life can effectively buffer against the impact of negative life events such as the COVID-19 pandemic. They also suggest that intrinsic based aspirations centred on relationships and self-acceptance may be an important mechanism in how people choose to pursue life meaning during uncertain life events.

scholarly journals The impact of late-career job loss and genetic risk on body mass index: Evidence from variance polygenic scores

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Lauren L. Schmitz ◽  
Julia Goodwin ◽  
Jiacheng Miao ◽  
Qiongshi Lu ◽  
Dalton Conley
Keyword(s):  
Body Mass Index ◽  
Body Mass ◽  
Complex Traits ◽  
Job Loss ◽  
Past Research ◽  
Long Term Effects ◽  
Polygenic Scores ◽  
Show Evidence ◽  
Using Data ◽  
The Impact

AbstractUnemployment shocks from the COVID-19 pandemic have reignited concerns over the long-term effects of job loss on population health. Past research has highlighted the corrosive effects of unemployment on health and health behaviors. This study examines whether the effects of job loss on changes in body mass index (BMI) are moderated by genetic predisposition using data from the U.S. Health and Retirement Study (HRS). To improve detection of gene-by-environment (G × E) interplay, we interacted layoffs from business closures—a plausibly exogenous environmental exposure—with whole-genome polygenic scores (PGSs) that capture genetic contributions to both the population mean (mPGS) and variance (vPGS) of BMI. Results show evidence of genetic moderation using a vPGS (as opposed to an mPGS) and indicate genome-wide summary measures of phenotypic plasticity may further our understanding of how environmental stimuli modify the distribution of complex traits in a population.

Influence of nozzle exit geometrical parameters on supersonic jet decay

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Prasanta Kumar Mohanta ◽  
B. T. N. Sridhar ◽  
R. K. Mishra
Keyword(s):  
Aspect Ratio ◽  
Nozzle Exit ◽  
Ambient Air ◽  
Schlieren Image ◽  
Geometrical Parameters ◽  
Image Study ◽  
Aspect Ratios ◽  
Core Length ◽  
Supersonic Core Length ◽  
The Impact

Abstract Experiments and simulations were carried on C-D nozzles with four different exit geometry aspect ratios to investigate the impact of supersonic decay characteristics. Rectangular and elliptical exit geometries were considered for the study with various aspect ratios. Numerical simulations and Schlieren image study were studied and found the agreeable logical physics of decay and spread characteristics. The supersonic core decay was found to be of different length for different exit geometry aspect ratio, though the throat to exit area ratio was kept constant to maintain the same exit Mach number. The impact of nozzle exit aspect ratio geometry was responsible to enhance the mixing of primary flow with ambient air, without requiring a secondary method to increase the mixing characteristics. The higher aspect ratio resulted in better mixing when compared to lower aspect ratio exit geometry, which led to reduction in supersonic core length. The behavior of core length reduction gives the identical signature for both under-expanded and over-expanded cases. The results revealed that higher aspect ratio of the exit geometry produced smaller supersonic core length. The aspect ratio of cross section in divergent section of the nozzle was maintained constant from throat to exit to reduce flow losses.

scholarly journals Photovoltaic Power Forecasting: Assessment of the Impact of Multiple Sources of Spatio-Temporal Data on Forecast Accuracy

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1432
Author(s):  
Xwégnon Ghislain Agoua ◽  
Robin Girard ◽  
Georges Kariniotakis
Keyword(s):  
Satellite Images ◽  
Forecast Accuracy ◽  
Absolute Error ◽  
Data Sources ◽  
Test Case ◽  
Temporal Data ◽  
Multiple Sources ◽  
Forecasting Error ◽  
Spatio Temporal ◽  
The Impact

The efficient integration of photovoltaic (PV) production in energy systems is conditioned by the capacity to anticipate its variability, that is, the capacity to provide accurate forecasts. From the classical forecasting methods in the state of the art dealing with a single power plant, the focus has moved in recent years to spatio-temporal approaches, where geographically dispersed data are used as input to improve forecasts of a site for the horizons up to 6 h ahead. These spatio-temporal approaches provide different performances according to the data sources available but the question of the impact of each source on the actual forecasting performance is still not evaluated. In this paper, we propose a flexible spatio-temporal model to generate PV production forecasts for horizons up to 6 h ahead and we use this model to evaluate the effect of different spatial and temporal data sources on the accuracy of the forecasts. The sources considered are measurements from neighboring PV plants, local meteorological stations, Numerical Weather Predictions, and satellite images. The evaluation of the performance is carried out using a real-world test case featuring a high number of 136 PV plants. The forecasting error has been evaluated for each data source using the Mean Absolute Error and Root Mean Square Error. The results show that neighboring PV plants help to achieve around 10% reduction in forecasting error for the first three hours, followed by satellite images which help to gain an additional 3% all over the horizons up to 6 h ahead. The NWP data show no improvement for horizons up to 6 h but is essential for greater horizons.

Dependency of Machine Efficiency on the Thermal Behavior of Induction Machines

Machines ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 9
Author(s):  
Svenja Kalt ◽  
Karl Ludwig Stolle ◽  
Philipp Neuhaus ◽  
Thomas Herrmann ◽  
Alexander Koch ◽  
...  
Keyword(s):  
Thermal Behavior ◽  
Electric Vehicles ◽  
Thermal Load ◽  
Load Capacity ◽  
Maximum Load ◽  
Induction Machines ◽  
Electric Machines ◽  
Model Parameters ◽  
Dynamic Operating ◽  
The Impact

The consideration of the thermal behavior of electric machines is becoming increasingly important in the machine design for electric vehicles due to the adaptation to more dynamic operating points compared to stationary applications. Whereas, the dependency of machine efficiency on thermal behavior is caused due to the impact of temperature on the resulting loss types. This leads to a shift of efficiency areas in the efficiency diagram of electric machines and has a significant impact on the maximum load capability and an impact on the cycle efficiency during operation, resulting in a reduction in the overall range of the electric vehicle. Therefore, this article aims at analyzing the thermal load limits of induction machines in regard to actual operation using measured driving data of battery electric vehicles. For this, a thermal model is implemented using MATLAB® and investigations to the sensitivity of model parameters as well as analysis of the continuous load capacity, thermal load and efficiency in driving cycles under changing boundary conditions are conducted.

scholarly journals Participation in a Course-Based Undergraduate Research Experience Results in Higher Grades in the Companion Lecture Course

2020 ◽  
pp. 0013189X2096809
Author(s):  
Marsha Ing ◽  
James M. Burnette ◽  
Tarek Azzam ◽  
Susan R. Wessler
Keyword(s):  
Low Income ◽  
Undergraduate Research ◽  
Public Institutions ◽  
Research Experience ◽  
Stem Fields ◽  
Academic Characteristics ◽  
Course Grades ◽  
Undergraduate Science ◽  
Hispanic Serving ◽  
The Impact

Opportunities for large numbers of undergraduates to engage in authentic research experiences are limited in many large public institutions. These large public institutions serve the vast majority of students who are historically underrepresented in STEM fields, such as first-generation, low-income students of color. Although a course-based undergraduate research experience (CURE) is one scalable approach to providing such opportunities, there is limited evidence about the impact of participation, particularly for students historically underrepresented in science. This study provides evidence of the influence of student participation in a CURE on undergraduate science course grades using an experimental design and multiple years of data from students at a Hispanic-serving institution. Course grades were compared for five different science courses across five cohorts of students participating in a CURE ( n = 935) and a similar group of students who did not participate in the CURE ( n = 1,144). CURE students had significantly higher overall grades in a lecture course directly related to the CURE even after statistically adjusting for demographic and academic characteristics. Implications for CUREs as a model for improving science knowledge and achievement for students typically underrepresented in STEM fields are discussed.

The Effect of Vocal Alarms on Operator Mistrust

2000 ◽  
Vol 44 (22) ◽  
pp. 694-697
Author(s):  
James P. Bliss ◽  
Freida Kilpatrick
Keyword(s):  
Past Research ◽  
Primary Task ◽  
Duty To Warn ◽  
Complex Information ◽  
The Impact ◽  
Operator Workload

The use of alarms has increased in many operational areas because of increased reliance on automation and the duty to warn about system anomalies. Past research has supported the use of verbal alarms for relaying complex information. However, researchers have not considered the impact of vocal alarms on operator trust. In this research, 56 participants reacted to auditory alarms while performing a complex primary task. Half of the participants experienced vocal alarms, and the others experienced nonvocal alarms. Contrary to expectations, we noted that participants reacted to nonverbal alarms more quickly than verbal alarms. Furthermore, participants responded to verbal alarms more often than verbal alarms. We also noted that verbal alarms interfered with the primary task more than nonverbal alarms. We suggest that alarm designers alter verbal alarm onset algorithms during high operator workload.

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