A Novel Design of Landing Gear Oleo Strut Damper Using MR Fluid for Aircraft and UAV’s

Most landing gears used in aircraft employ very efficient oleo-pneumatic dampers to absorb and dissipate the impact kinetic energy of the aircraft body frame. A single-acting shock absorber is most commonly used in the oleo strut that has a metering pin extending through the orifice, which can vary the orifice area upon compression and extension of the strut. This variation is adjusted by shaping the metering pin so that the strut load is fairly constant under dynamic loading. In this paper, it is proposed to further change the damping coefficient as a function of time in order to achieve a semi-active control of the aircraft vibrations during landing by using Magnetorheological (MR) fluid in the Oleo. With the metering pin designed for a nominal flight condition, further variation in the fluid viscosity would help achieve the optimal performance in off-nominal flight conditions. A simulation approach is employed to show the effect of different profiles for viscosity variation in the MR fluid. The utility of such a damper can be very well exploited to include different criteria such as the landing distance after touchdown. This type of system can be used also in Unmanned Aerial Vehicle (UAV) application where the focus of design may be to accomplish the task without the consideration of passenger comfort.

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Effect of Tapered Metering Pin on Magnetorheological Fluid Subjected to Shock Loading

Materials Science Forum ◽

10.4028/www.scientific.net/msf.856.3 ◽

2016 ◽

Vol 856 ◽

pp. 3-8

Author(s):

Yuzo Shimizu ◽

Shintaro Takagi ◽

Tatsuo Sawada

Keyword(s):

Magnetic Field ◽

Field Strength ◽

Shock Loading ◽

Shock Absorber ◽

Magnetorheological Fluid ◽

Mr Fluid ◽

Orifice Area ◽

Measured Displacement ◽

Calculated Velocity ◽

Piston Stroke

This study reports on effects of tapered metering pins on a magnetorheological (MR) fluid subjected to shock loading. Using four types of tapered metering pins, we conducted drop impact tests and qualitative analysis of effects of tapered pins on an MR fluid with a magnetic field applied around an orifice area. We measured the displacement of a piston and calculated velocity and acceleration from the measured displacement. The four different tapered pins changed a piston stroke to bring the impacting mass to rest. The results indicated that the shape of the pins has an effect on the entire process of shock absorption, whereas magnetic field strength has an effect on the post-peak behavior only. These results show that a tapered metering pin has applicability to a shock absorber using an MR fluid.

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Stochastic simulation for determining the design flood of cascade reservoir systems

Hydrology Research ◽

10.2166/nh.2011.002 ◽

2012 ◽

Vol 43 (1-2) ◽

pp. 54-63 ◽

Cited By ~ 6

Author(s):

Baohong Lu ◽

Huanghe Gu ◽

Ziyin Xie ◽

Jiufu Liu ◽

Lejun Ma ◽

...

Keyword(s):

Simulation Model ◽

Stochastic Simulation ◽

Southern China ◽

Flow Simulation ◽

Simulation Method ◽

Simulation Approach ◽

Design Flood ◽

Design Values ◽

Stochastic Simulation Model ◽

The Impact

Stochastic simulation is widely applied for estimating the design flood of various hydrosystems. The design flood at a reservoir site should consider the impact of upstream reservoirs, along with any development of hydropower. This paper investigates and applies a stochastic simulation approach for determining the design flood of a complex cascade of reservoirs in the Longtan watershed, southern China. The magnitude of the design flood when the impact of the upstream reservoirs is considered is less than that without considering them. In particular, the stochastic simulation model takes into account both systematic and historical flood records. As the reliability of the frequency analysis increases with more representative samples, it is desirable to incorporate historical flood records, if available, into the stochastic simulation model. This study shows that the design values from the stochastic simulation method with historical flood records are higher than those without historical flood records. The paper demonstrates the advantages of adopting a stochastic flow simulation approach to address design-flood-related issues for a complex cascade reservoir system.

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Energy absorbed ability and damage analysis for honeycomb sandwich material of bio-inspired micro aerial vehicle under low velocity impact

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406220975427 ◽

2020 ◽

pp. 095440622097542

Author(s):

Jianxun Du ◽

Peng Hao ◽

Mabao Liu ◽

Rui Xue ◽

Lin’an Li

Keyword(s):

Honeycomb Structure ◽

Low Velocity Impact ◽

Parameter Study ◽

Low Velocity ◽

Micro Aerial Vehicle ◽

Thin Walled Structures ◽

Wide Range ◽

Aerial Vehicle ◽

Thin Walled ◽

The Impact

Because of the advantages of light weight, small size, and good maneuverability, the bio-inspired micro aerial vehicle has a wide range of application prospects and development potential in military and civil areas, and has become one of the research hotspots in the future aviation field. The beetle’s elytra possess high strength and provide the protection of the abdomen while being functional to guarantee its flight performance. In this study, the internal microstructure of beetle’s elytra was observed by scanning electron microscope (SEM), and a variety of bionic thin-walled structures were proposed and modelled. The energy absorption characteristics and protective performance of different configurations of thin-walled structures with hollow columns under impact loading was analyzed by finite element method. The parameter study was carried out to show the influence of the velocity of impactor, the impact angle of the impactor and the wall thickness of honeycomb structure. This study provides an important inspiration for the design of the protective structure of the micro aerial vehicle.

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A Novel Gemini Cationic Viscoelastic Surfactant-Based Fluid for High Temperature Well Stimulation Applications

10.2118/206297-ms ◽

2021 ◽

Author(s):

Dawn Friesen ◽

Brian Seymour ◽

Aaron Sanders

Keyword(s):

Thermal Stability ◽

High Temperature ◽

Chain Length ◽

Surfactant Concentration ◽

Gemini Surfactant ◽

Alkyl Chain ◽

Friction Reduction ◽

Fluid Viscosity ◽

Viscoelastic Surfactant ◽

The Impact

Abstract Viscoelastic surfactant (VES)-based fracturing fluids can reduce the risk of formation damage when compared with conventional polymer-based fracturing systems. However, many VES systems lose viscoelasticity rapidly under high-temperature conditions, leading to high fluid leakoff and problems in proppant placement. A gemini cationic VES-based system offering thermal stability above 250°F and its efficiency in friction reduction is presented in this paper. Rheology measurements were conducted on viscoelastic cationic gemini surfactant fluids as a function of temperature (70 – 300°F) and surfactant concentration. The length of surfactant alkyl chain was varied to investigate the impact of surfactant chain length on VES fluid viscosity at elevated temperatures. The effect of flow rate on friction reduction capability of the surfactant fluid was measured on a friction flow loop. Foam rheology measurements were conducted to evaluate the VES fluid's ability to maintain high temperature viscosity with reduced surfactant concentration. A gemini cationic surfactant was used to prepare a viscoelastic surfactant system that could maintain viscosity over 50 cP at a shear rate of 100 s−1up to at least 250°F. With this system, viscoelastic gel viscosity was maintained without degradation for over 18 hours at 250°F, and the fluid showed rapid shear recovery throughout. Decreasing the average alkyl chain length on the surfactant reduced the maximum working temperature of the resulting viscoelastic gel and showed the critical influence of surfactant structure on the resulting fluid performance. The presence of elongated, worm-like micelles in the fluid provided polymer-like friction reduction even at low surfactant concentrations, with friction reduction of over 70% observed during pumping (relative to fresh water) up to a critical Reynolds number. Energized fluids could also be formulated with the gemini surfactant to give foam fluids suitable for hydraulic fracturing or wellbore cleanouts. The resulting viscoelastic surfactant foams had viscosities over 50 cP up to at least 300°F with both nitrogen and carbon dioxide as the gas phase. The information presented in this paper is important for various field applications where thermal stability of the treatment fluid is essential. This will hopefully expand the use of VES-based systems as an alternative to conventional polymer systems in oilfield applications where a less damaging viscosified fluid system is required.

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Impact of N-Shaped Wing Morphing on Solar-Powered Aircraft

Unmanned Systems ◽

10.1142/s2301385021500138 ◽

2020 ◽

pp. 1-12

Author(s):

Mostafa E. El-Salamony ◽

Mohamed A. Aziz

Keyword(s):

Solar Energy ◽

Lift Coefficient ◽

Morphing Wing ◽

Aerial Vehicles ◽

Aircraft Performance ◽

Aerial Vehicle ◽

Solar Powered ◽

Two Parameters ◽

Wing Morphing ◽

The Impact

Generally, unmanned aerial vehicles and micro aerial vehicles depend on batteries or conventional fuel as a source of energy. These sources of energy have limited flight time, relatively high cost, and also a certain level of pollutants. Solar energy applied to aerial vehicles is an excellent alternative way to overcome other sources of energy’s disadvantage. This study aimed to design a solar-powered aerial vehicle to achieve continuous flight on Earth. The efficiency of the solar system is related to the absorbed sun rays. The concept of an anti-symmetric N-shaped morphing wing is a good idea to increase the collected solar energy during the daily sun path. But this comes with the penalty of side forces and moments due to the anti-symmetry of the wing. This paper introduces a study for two parameters that strongly affect the aerodynamics of the N-shaped morphing wing; the dihedral part angle and the dihedral part length. The impact of the dihedral angle decreases the lift coefficient and increases the drag coefficient. The impact of the morphing wing on the aircraft performance is also considered.

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Automated Bale Mapping Using Machine Learning and Photogrammetry

Remote Sensing ◽

10.3390/rs13224675 ◽

2021 ◽

Vol 13 (22) ◽

pp. 4675

Author(s):

William Yamada ◽

Wei Zhao ◽

Matthew Digman

Keyword(s):

Lower Cost ◽

Mean Squared Error ◽

Spatial Clustering ◽

Mean Average Precision ◽

Average Precision ◽

Data Set ◽

Map Projection ◽

Squared Error ◽

Aerial Vehicle ◽

The Impact

An automatic method of obtaining geographic coordinates of bales using monovision un-crewed aerial vehicle imagery was developed utilizing a data set of 300 images with a 20-megapixel resolution containing a total of 783 labeled bales of corn stover and soybean stubble. The relative performance of image processing with Otsu’s segmentation, you only look once version three (YOLOv3), and region-based convolutional neural networks was assessed. As a result, the best option in terms of accuracy and speed was determined to be YOLOv3, with 80% precision, 99% recall, 89% F1 score, 97% mean average precision, and a 0.38 s inference time. Next, the impact of using lower-cost cameras was evaluated by reducing image quality to one megapixel. The lower-resolution images resulted in decreased performance, with 79% precision, 97% recall, 88% F1 score, 96% mean average precision, and 0.40 s inference time. Finally, the output of the YOLOv3 trained model, density-based spatial clustering, photogrammetry, and map projection were utilized to predict the geocoordinates of the bales with a root mean squared error of 2.41 m.

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The impact of nonresponse in different survey stages on the precision of prevalence estimates for multi-stage survey studies

BMC Research Notes ◽

10.1186/s13104-021-05840-0 ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Ming Ma ◽

Sophie Rosenberg ◽

Alexander M. Kaizer

Keyword(s):

Survey Research ◽

State Level ◽

Simulation Approach ◽

Multi Stage ◽

Margin Of Error ◽

Prevalence Estimates ◽

Three Stages ◽

Nonresponse Rate ◽

The Mean ◽

The Impact

Abstract Objective While it is known that nonresponse might produce biased results and impair the precision of results in survey research studies, the pattern of the impact on the precision of estimates due to the nonresponse in different survey stages is historically overlooked. Having this type of information is essential when creating recruitment plans. This study proposes to examine and compare the effect of nonresponse in different stages on the precision of prevalence estimates in multi-stage survey studies. Based on data from a state level survey, a simulation approach was used to generate datasets with different nonresponse rates in three stages. The margin of error was then compared between the datasets with nonresponse at three different survey stages for 12 outcomes. Results At the same nonresponse rate, the mean margin of error was greater for the data with nonresponse at higher stages. Additionally, as the nonresponse rate increased, precision was more inflated within the data with higher stage nonresponse. This suggests that the effort used to recruit the primary sampling units is more crucial to improve the precision of estimates in multi-stage survey studies.

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Measuring Market Risk of Commercial Banks Implementing VaR with Historical Simulation Approach

10.47260/jafb/1144 ◽

2021 ◽

pp. 79-99

Author(s):

Minhaz-Ul Haq

Keyword(s):

Stock Prices ◽

Commercial Banks ◽

Value At Risk ◽

First Generation ◽

Market Risk ◽

Jel Classification ◽

Simulation Approach ◽

Share Prices ◽

Historical Simulation ◽

The Impact

This paper attempts to picture the impact of the market risk of ten commercial banks located in Bangladesh with the help of a non-parametric model known as the Historical Simulation Approach over the course of eight years. These banks' daily stock prices were used as inputs and analyzed in Microsoft Excel by means of Percentile and LN function. The study revealed market risk exposure as third, second-and first-generation banks from the least to the highest. It also pointed out the ups and downs of these banks' share prices in the selected period. Further analysis showed the portfolio VaR estimation for different time intervals. JEL classification numbers: G32. Keywords: Value-at-risk, Historical Simulation, Market Risk, Confidence Interval.

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Dynamic Stability and Control of a Manipulating Unmanned Aerial Vehicle

International Journal of Aerospace Engineering ◽

10.1155/2018/3481328 ◽

2018 ◽

Vol 2018 ◽

pp. 1-13 ◽

Cited By ~ 2

Author(s):

Yunping Liu ◽

Xijie Huang ◽

Yonghong Zhang ◽

Yukang Zhou

Keyword(s):

Stability Analysis ◽

Lyapunov Exponent ◽

Dynamic Stability ◽

Unmanned Aerial Vehicle ◽

Impedance Control ◽

System Stability ◽

Constructive Method ◽

Aerial Vehicle ◽

And Control ◽

The Impact

This paper focuses on the dynamic stability analysis of a manipulator mounted on a quadrotor unmanned aerial vehicle, namely, a manipulating unmanned aerial vehicle (MUAV). Manipulator movements and environments interaction will extremely affect the dynamic stability of the MUAV system. So the dynamic stability analysis of the MUAV system is of paramount importance for safety and satisfactory performance. However, the applications of Lyapunov’s stability theory to the MUAV system have been extremely limited, due to the lack of a constructive method available for deriving a Lyapunov function. Thus, Lyapunov exponent method and impedance control are introduced, and the Lyapunov exponent method can establish the quantitative relationships between the manipulator movements and the dynamics stability, while impedance control can reduce the impact of environmental interaction on system stability. Numerical simulation results have demonstrated the effectiveness of the proposed method.

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