scholarly journals In-flight Wind Field Identification and Prediction of Parafoil Systems

2020 ◽  
Vol 10 (6) ◽  
pp. 1958
Author(s):  
Haitao Gao ◽  
Jin Tao ◽  
Matthias Dehmer ◽  
Frank Emmert-Streib ◽  
Qinglin Sun ◽  
...  
Keyword(s):  
Wind Field ◽  
Combination Method ◽  
Essential Factor ◽  
Wind Fields ◽  
System A ◽  
Wind Identification ◽  
Field Identification ◽  
Field Information ◽  
System Information ◽  
Low Altitude

The wind field is an essential factor that affects accurate homing and flare landing of parafoil systems. In order to obtain the ambient wind field during the descent of a parafoil system, a combination method of in-flight wind field identification and prediction is proposed. First, a wind identification method only using global position system information is derived based on the flight dynamics of parafoil systems. Then a wind field prediction model is constructed using the atmospheric dynamics, and the low-altitude wind field is predicted based on the identified wind field of high-altitude. Finally, simulations of wind field identification and prediction are conducted. The results demonstrate that the proposed method can identify the wind fields precisely and also predict the wind fields reasonably. This method can potentially be applied in practical parafoil systems to provide wind field information for homing tasks.

scholarly journals Engineering Comprehensive Model of Complex Wind Fields for Flight Simulation

Aerospace ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 145
Author(s):  
Jianwei Chen ◽  
Liangming Wang ◽  
Jian Fu ◽  
Zhiwei Yang
Keyword(s):  
Wind Field ◽  
Three Dimensional ◽  
Great Influence ◽  
Spatial Location ◽  
Flight Simulation ◽  
Comprehensive Model ◽  
Flight Trajectory ◽  
Wind Fields ◽  
Wind Field Simulation ◽  
Low Level Jet

A complex wind field refers to the typical atmospheric disturbance phenomena existing in nature that have a great influence on the flight of aircrafts. Aimed at the issues involving large volume of data, complex computations and a single model in the current wind field simulation approaches for flight environments, based on the essential principles of fluid mechanics, in this paper, wind field models for two kinds of wind shear such as micro-downburst and low-level jet plus three-dimensional atmospheric turbulence are established. The validity of the models is verified by comparing the simulation results from existing wind field models and the measured data. Based on the principle of vector superposition, three wind field models are combined in the ground coordinate system, and a comprehensive model of complex wind fields is established with spatial location as the input and wind velocity as the output. The model is applied to the simulated flight of a rocket projectile, and the change in the rocket projectile’s flight attitude and flight trajectory under different wind fields is analyzed. The results indicate that the comprehensive model established herein can reasonably and efficiently reflect the influence of various complex wind field environments on the flight process of aircrafts, and that the model is simple, extensible, and convenient to use.

Simulation of the wind fields over complex terrain with coupling of CFD and WRF

2021 ◽  
pp. 1-12
Author(s):  
Xiaoyu Luo ◽  
Yiwen Cao
Keyword(s):  
Wind Speed ◽  
Wind Field ◽  
Complex Terrain ◽  
Civil Engineering ◽  
Meteorological Data ◽  
Mass Conservation ◽  
Coupling Method ◽  
Wind Fields ◽  
Civil Structures ◽  
Civil Engineers

In the field of civil engineering, the meteorological data available usually do not have the detailed information of the wind near a certain site. However, the detailed information of the wind field during typhoon is important for the wind-resistant design of civil structures. Furthermore, the resolution of the meteorological data available by the civil engineers is too coarse to be applicable. Therefore it is meaningful to obtain the detailed information of the wind fields based on the meteorological data provided by the meteorological department. Therefore, in the present study, a one-way coupling method between WRF and CFD is adopted and a method to keep the mass conservation during the simulation in CFD is proposed. It is found that using the proposed one-way coupling method, the predicted wind speed is closer to the measurement. And the curvature of the wind streamline during typhoon is successfully reproduced.

scholarly journals Effect of high altitude on human placental amino acid transport

2020 ◽  
Vol 128 (1) ◽  
pp. 127-133 ◽  
Author(s):  
Owen. R. Vaughan ◽  
Fredrick Thompson ◽  
Ramón. A. Lorca ◽  
Colleen G. Julian ◽  
Theresa L. Powell ◽  
...  
Keyword(s):  
Birth Weight ◽  
Amino Acid ◽  
High Altitude ◽  
Sea Level ◽  
Amino Acid Transport ◽  
Acid Uptake ◽  
Acid Transport ◽  
Transport Capacity ◽  
System A ◽  
Low Altitude

Women residing at high altitudes deliver infants of lower birth weight than at sea level. Birth weight correlates with placental system A-mediated amino acid transport capacity, and severe environmental hypoxia reduces system A activity in isolated trophoblast and the mouse placenta. However, the effect of high altitude on human placental amino acid transport remains unknown. We hypothesized that microvillous membrane (MVM) system A and system L amino acid transporter activity is lower in placentas of women living at high altitude compared with low-altitude controls. Placentas were collected at term from healthy pregnant women residing at high altitude (HA; >2,500 m; n = 14) or low altitude (LA; <1,700 m; n = 14) following planned, unlabored cesarean section. Birth weight, but not placenta weight, was 13% lower in HA pregnancies (2.88 ± 0.11 kg) compared with LA (3.30 ± 0.07 kg, P < 0.01). MVM erythropoietin receptor abundance, determined by immunoblot, was greater in HA than in LA placentas, consistent with lower placental oxygen levels at HA. However, there was no effect of altitude on MVM system A or L activity, determined by Na+-dependent [14C]methylaminoisobutyric acid uptake and [3H]leucine uptake, respectively. MVM abundance of glucose transporters (GLUTs) 1 and 4 and basal membrane GLUT4 were also similar in LA and HA placentas. Low birth weights in the neonates of women residing at high altitude are not a consequence of reduced placental amino acid transport capacity. These observations are in general agreement with studies of IUGR babies at low altitude, in which MVM system A activity is downregulated only in growth-restricted babies with significant compromise. NEW & NOTEWORTHY Babies born at high altitude are smaller than at sea level. Birth weight is dependent on growth in utero and, in turn, placental nutrient transport. We determined amino acid transport capacity in placentas collected from women resident at low and high altitude. Altitude did not affect system A amino acid transport across the syncytiotrophoblast microvillous membrane, suggesting that impaired placental amino acid transport does not contribute to reduced birth weight in this high-altitude population.

scholarly journals An overview of various kinds of wind effects on unmanned aerial vehicle

2019 ◽  
Vol 52 (7-8) ◽  
pp. 731-739 ◽  
Author(s):  
Bo Hang Wang ◽  
Dao Bo Wang ◽  
Zain Anwar Ali ◽  
Bai Ting Ting ◽  
Hao Wang
Keyword(s):  
Unmanned Aerial Vehicle ◽  
Great Influence ◽  
Wind Disturbance ◽  
Wind Fields ◽  
Wind Model ◽  
Aerial Vehicle ◽  
Low Altitude ◽  
The Stability ◽  
The Mathematical Model ◽  
Vehicle Movement

Attitude, speed, and position of unmanned aerial vehicles are susceptible to wind disturbance. The types, characteristics, and mathematical models of the wind, which have great influence on unmanned aerial vehicle in the low-altitude environment, are summarized, including the constant wind, turbulent flow, many kinds of wind shear, and the propeller vortex. Combined with the mathematical model of the unmanned aerial vehicle, the mechanism of unmanned aerial vehicle movement in the wind field is illustrated from three different kinds of viewpoints including velocity viewpoint, force viewpoint, and energy viewpoint. Some simulation tests have been implemented to show the effects of different kinds of wind on unmanned aerial vehicle’s path and flight states. Finally, some proposals are presented to tell reader in which condition, which wind model should be added to simulation, and how to enhance the stability of unmanned aerial vehicle for different kinds of wind fields.

The Feasibility of a Helmet-Mounted Sight as a Control Device

1966 ◽  
Vol 8 (5) ◽  
pp. 417-425 ◽  
Author(s):  
Robert M. Nicholson
Keyword(s):  
High Speed ◽  
Angular Rate ◽  
Control Device ◽  
Experimental Program ◽  
Moving Targets ◽  
Human Capabilities ◽  
Laboratory Environment ◽  
System A ◽  
Three Phase ◽  
Low Altitude

The purpose of this research was to investigate the practicality of a helmet-mounted sight as an operational element in a quick-reaction bore-sighting system. A three-phase experimental program was conducted to determine the human capabilities with the helmet-mounted sight. In a laboratory environment sighting accuracies were obtained on both static and moving targets. Field test data were obtained during high-speed, low-altitude flights. The series of tests indicated that the accuracy of the sighting process can be expected to vary between a fraction of a degree and four degrees depending on target angular rate and the target sighting angle.

scholarly journals A Feasibility Study of Simulating the Micro-Scale Wind Field for Wind Energy Applications by NWP/CFD Model with Improved Coupling Method and Data Assimilation

Energies ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2549
Author(s):  
Shaohui Li ◽  
Xuejin Sun ◽  
Riwei Zhang ◽  
Chuanliang Zhang
Keyword(s):  
Data Assimilation ◽  
Wind Energy ◽  
Wind Field ◽  
Weather Prediction ◽  
Model Performance ◽  
Coupling Method ◽  
Cfd Model ◽  
Wind Fields ◽  
Micro Scale ◽  
Cfd Models

Understanding the details of micro-scale wind fields is important in the development of wind energy. Research has proven that coupling Numerical Weather Prediction (NWP) and Computational Fluid Dynamics (CFD) models is a better approach for micro-scale wind field simulation. The main purpose of this work is to improve the NWP/CFD model performance in two parts: (i) developing a new coupling method that is more suitable for complex terrain between the NWP and CFD models, and (ii) applying a data assimilation system in the CFD model. Regarding part (i), in order to solve the problem of great topographical difference at the domain boundaries between the two models, Cressman interpolation is utilized to impose the NWP model wind on the CFD model boundaries. In part (ii), an assimilation method, nudging, to apply assimilation of observations into the CFD model is explored. Based on the Cressman interpolation coupling method, a preliminary implementation of data assimilation is performed. The results show that the NWP/CFD model with the improved coupling method may capture the details of micro-scale wind fields more accurately. Using data assimilation, the NWP/CFD model performance may be further improved by cooperating observation data.

Parametric Modeling of Transitioning Cyclone Wind Fields for Risk Assessment Studies in the Western North Pacific

2015 ◽  
Vol 54 (3) ◽  
pp. 624-642 ◽  
Author(s):  
T. Loridan ◽  
S. Khare ◽  
E. Scherer ◽  
M. Dixon ◽  
E. Bellone
Keyword(s):  
Risk Assessment ◽  
North Pacific ◽  
Wind Field ◽  
Western North Pacific ◽  
Parametric Modeling ◽  
Transition Phase ◽  
Wind Fields ◽  
Extratropical Transition ◽  
Starting Point ◽  
Assessment Systems

AbstractProbabilistic risk assessment systems for tropical cyclone hazards rely on large ensembles of model simulations to characterize cyclones tracks, intensities, and the extent of the associated damaging winds. Given the computational costs, the wind field is often modeled using parametric formulations that make assumptions that are based on observations of tropical systems (e.g., satellite, or aircraft reconnaissance). In particular, for the Northern Hemisphere, most of the damaging contribution is assumed to be from the right of the moving cyclone, with the left-hand-side winds being much weaker because of the direction of storm motion. Recent studies have highlighted that this asymmetry assumption does not hold for cyclones undergoing extratropical transitions around Japan. Transitioning systems can exhibit damaging winds on both sides of the moving cyclone, with wind fields often characterized as resembling a horseshoe. This study develops a new parametric formulation of the extratropical transition phase for application in risk assessment systems. A compromise is sought between the need to characterize the horseshoe shape while keeping the formulation simple to allow for implementation within a risk assessment framework. For that purpose the tropical wind model developed by Willoughby et al. is selected as a starting point and parametric bias correction fields are applied to build the target shape. Model calibration is performed against a set of 37 extratropical transition cases simulated using the Weather Research and Forecasting Model. This newly developed parametric model of the extratropical transition phase shows an ability to reproduce wind field features observed in the western North Pacific Ocean while using only a restricted number of input parameters.

A study of function-based diagnosis strategy and testability analysis for a system

2011 ◽  
Vol 226 (1) ◽  
pp. 273-282 ◽  
Author(s):  
Y-T Tsai ◽  
Y-Y Hsu
Keyword(s):  
Hydraulic System ◽  
Block Diagram ◽  
Fault Isolation ◽  
Functional Block Diagram ◽  
Diagnostic Ability ◽  
System A ◽  
Study Results ◽  
System Maintenance ◽  
System Information ◽  
Test Points

A good diagnostic policy can not only shorten the detection time of faults but also improve the effectiveness of system maintenance. This paper presents a function-based diagnosis strategy that provides a helpful methodology for fault identification. The diagnosis trees of the systems are constructed based on a functional block diagram consisting of function elements (FEs) and test points (TPs). The correlations between the FEs and the TPs are first analysed according to system information flows. Two weighted indexes for fault detection and fault isolation are defined to determine the priority of these TPs in testing. Several parameters related to diagnostic ability are also introduced to provide an evaluated approach for system testability. The diagnostic steps and costs between traditional sequential testing and the function-based diagnosing are compared. The study results may be useful in planning diagnosis actions and testability design for a system. A hydraulic system is used as an example in order to depict the proposed methods.

Quantification of NOX Emissions Based on Car MAX-DOAS Measurements over Beijing and Impacts of Wind Field

2020 ◽  
Author(s):  
Xinghong Cheng
Keyword(s):  
Spatial Distribution ◽  
Wind Speed ◽  
Wind Field ◽  
Meteorological Condition ◽  
Emission Rates ◽  
Wind Fields ◽  
Vertical Column ◽  
Wind Speeds ◽  
South Central ◽  
The Mean

&lt;p&gt;We carried out 14 days of Car MAX-DOAS experiments on the 6th Ring Rd of Beijing in January, September and October, 2014. The tropospheric vertical column densities (VCD) of NO&lt;sub&gt;2&lt;/sub&gt; are retrieved and used to estimate the emissions of NO&lt;sub&gt;x&lt;/sub&gt;. The offline LAPS-WRF-CMAQ model system is used to simulate wind fields by assimilation of observational data and calculate the NO&lt;sub&gt;2&lt;/sub&gt; to NO&lt;sub&gt;x&lt;/sub&gt; concentration ratios. The NO&lt;sub&gt;X&lt;/sub&gt; emissions in Beijing for different seasons derived from Car MAX-DOAS measurements are compared with the multi-resolution emission inventory in China for 2012 (MEIC 2012), and impacts of wind field on estimated emissions and its uncertainties are also investigated. Results show that the NO&lt;sub&gt;2&lt;/sub&gt; VCD is higher in January than other two months and it is typically larger at the southern parts of the 6th Ring Road than the northern parts of it. Wind field has obvious impacts on the spatial distribution of NO&lt;sub&gt;2&lt;/sub&gt; VCD, and the mean NO&lt;sub&gt;2&lt;/sub&gt; VCD with south wind at most sampling points along the 6th Ring Rd is higher than north wind. The journey-to-journey variation pattern of estimated NO&lt;sub&gt;X&lt;/sub&gt; emissions rates (E&lt;sub&gt;NOX&lt;/sub&gt;) is consistent with that of the NO&lt;sub&gt;2&lt;/sub&gt; VCD, and E&lt;sub&gt;NOX &lt;/sub&gt;is mainly determined by the NO2 VCD. In addition, the journey-to-journey E&lt;sub&gt;NOX&lt;/sub&gt; in the same month is different and it is affected by wind speed, the ratio of NO&lt;sub&gt;2&lt;/sub&gt; and NOx concentration and the decay rate of NO&lt;sub&gt;X&lt;/sub&gt; from the emission sources to measured positions under different meteorological condition. The E&lt;sub&gt;NOX&lt;/sub&gt; ranges between 6.46&amp;#215;10&lt;sup&gt;25&lt;/sup&gt; and 50.05&amp;#215;10&lt;sup&gt;25&lt;/sup&gt; molec s&lt;sup&gt;-1&lt;/sup&gt;. The averaged E&lt;sub&gt;NOX&lt;/sub&gt; during every journey in January, September and October are respectively 35.87&amp;#215;10&lt;sup&gt;25&lt;/sup&gt;, 20.34&amp;#215;10&lt;sup&gt;25&lt;/sup&gt;, 8.96&amp;#215;10&lt;sup&gt;25&lt;/sup&gt; molec s&lt;sup&gt;-1&lt;/sup&gt;. The estimated E&lt;sub&gt;NOX&lt;/sub&gt; after removing the simulated error of wind speed and observed deviation of NO&lt;sub&gt;2&lt;/sub&gt; VCD are found to be mostly closer to the MEIC 2012, but sometimes E&lt;sub&gt;NOX &lt;/sub&gt;is lower or higher and it indicates that the MEIC 2012 might be overestimate or underestimate the true emissions. The estimated E&lt;sub&gt;NOX&lt;/sub&gt; on January 27 and September 19 are obviously higher than other journeys in the same month because the mean NO&lt;sub&gt;2&lt;/sub&gt; VCD and Leighton ratio during these two periods are larger, and corresponding wind speeds are smaller. Additionally, because south wind may affect the spatial distribution of mean NO&lt;sub&gt;2&lt;/sub&gt; VCD in Beijing which is downwind of south-central&amp;#160;regions of Hebei province with high source emission rates, the uncertainty of the estimated E&lt;sub&gt;NOX&lt;/sub&gt; with south wind will be increased.&lt;/p&gt;

Sign in / Sign up

Export Citation Format

Share Document