Penetration Efficiency as a Function of Target Obliquity and Projectile Pitch

2013 ◽  
Vol 80 (3) ◽  
Author(s):  
Charles E., Jr. Anderson ◽  
Thilo Behner ◽  
Volker Hohler
Keyword(s):  
Pitch Angle ◽  
Asymmetric Behavior ◽  
Empirical Relations ◽  
Penetration Data ◽  
D 20 ◽  
Yaw Angle ◽  
Good Agreement ◽  
Blunt Nose

The influence of pitch (vertical yaw) angle on the penetration reduction of rod projectiles into oblique targets has been investigated for tungsten sinter alloy rods with a blunt nose and L/D = 20. Semi-infinite RHA targets with an obliquity of 30 deg, 45 deg, and 60 deg were impacted at 1650 m/s. The pitch angles were varied between ±90 deg. The strong asymmetric behavior of the target crater is dependent on whether the pitch is positive or negative relative to the obliquity of the target. The experiments provide a good overview of the penetration characteristics of long rods for the whole pitch angle range. The penetration data are described by empirical relations that show good agreement with the experiments.

scholarly journals A peduncle detection method of tomato for autonomous harvesting

2021 ◽  
Author(s):  
Jiacheng Rong ◽  
Guanglin Dai ◽  
Pengbo Wang
Keyword(s):  
Pose Estimation ◽  
Pitch Angle ◽  
Detection Method ◽  
Geometric Model ◽  
Average Error ◽  
Long Distance ◽  
End Effector ◽  
Key Points ◽  
Yaw Angle ◽  
Cutting Point

AbstractFor automating the harvesting of bunches of tomatoes in a greenhouse, the end-effector needs to reach the exact cutting point and adaptively adjust the pose of peduncles. In this paper, a method is proposed for peduncle cutting point localization and pose estimation. Images captured in real time at a fixed long-distance are detected using the YOLOv4-Tiny detector with a precision of 92.7% and a detection speed of 0.0091 s per frame, then the YOLACT +  + Network with mAP of 73.1 and a time speed of 0.109 s per frame is used to segment the close-up distance. The segmented peduncle mask is fitted to the curve using least squares and three key points on the curve are found. Finally, a geometric model is established to estimate the pose of the peduncle with an average error of 4.98° in yaw angle and 4.75° in pitch angle over the 30 sets of tests.

scholarly journals Cone Algorithm of Spinning Vehicles under Dynamic Coning Environment

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Shuang-biao Zhang ◽  
Xing-cheng Li ◽  
Zhong Su
Keyword(s):  
Pitch Angle ◽  
Euler Angle ◽  
Roll Angle ◽  
Angle Error ◽  
Attitude Error ◽  
Spinning Process ◽  
Cone Algorithm ◽  
Definition Of ◽  
Yaw Angle ◽  
The Relationship

Due to the fact that attitude error of vehicles has an intense trend of divergence when vehicles undergo worsening coning environment, in this paper, the model of dynamic coning environment is derived firstly. Then, through investigation of the effect on Euler attitude algorithm for the equivalency of traditional attitude algorithm, it is found that attitude error is actually the roll angle error including drifting error and oscillating error, which is induced directly by dynamic coning environment and further affects the pitch angle and yaw angle through transferring. Based on definition of the cone frame and cone attitude, a cone algorithm is proposed by rotation relationship to calculate cone attitude, and the relationship between cone attitude and Euler attitude of spinning vehicle is established. Through numerical simulations with different conditions of dynamic coning environment, it is shown that the induced error of Euler attitude fluctuates by the variation of precession and nutation, especially by that of nutation, and the oscillating frequency of roll angle error is twice that of pitch angle error and yaw angle error. In addition, the rotation angle is more competent to describe the spinning process of vehicles under coning environment than Euler angle gamma, and the real pitch angle and yaw angle are calculated finally.

Examination of the Flow Separation Characteristics Around a Streamlined Axisymmetric Shape

2005 ◽  
Author(s):  
C. R. Baker ◽  
T. L. Jeans ◽  
A. G. Gerber ◽  
A. G. L. Holloway ◽  
G. D. Watt
Keyword(s):  
Axisymmetric Body ◽  
Hydrodynamic Forces ◽  
The Body ◽  
Estimation Methods ◽  
Body Region ◽  
Force Estimation ◽  
Uncertainty Range ◽  
Flow Features ◽  
Yaw Angle ◽  
Good Agreement

Using computational fluid dynamics (CFD), a study was conducted to predict the hydrodynamic forces and moments on an axisymmetric body over a range of yaw angles and Reynolds numbers. Computational results for hydrodynamic forces and moments show good agreement with experimental data, being within the experimental uncertainty range at most yaw angles. Deviations outside of the uncertainty range occurred for the lateral (Y) force values at yaw angles greater than 15 degrees. The development of the after-body vortex shows good agreement with experimental observation. Primary and secondary separation points and shear stress streamline behaviour are also compared with experiment data at a yaw angle of 24 degrees. Results are discussed with a view to identifying flow features critical to the development of new force estimation methods. The after-body vortex, at increasing yaw angles, influences the overall force and moment predictions through a complex interaction between the transport of after-body vorticity and the detachment/reattachment locations of the boundary layer. Adequate modeling of this after-body region is increasingly important at high yaw angles. One of the most important features that influences the overall forces and moments is the circumferential position of shear layer detachment and reattachment, which have a direct impact on the pressure distribution along the body.

Computation of Hoisting Forces on Wind Turbine Blades Using Computation Fluid Dynamics

2013 ◽  
Vol 446-447 ◽  
pp. 452-457 ◽  
Author(s):  
Yong Wang ◽  
De Tian ◽  
Wei He
Keyword(s):  
Fluid Dynamics ◽  
Wind Turbine ◽  
Pitch Angle ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Azimuth Angle ◽  
Wind Turbine Blades ◽  
Mesh Model ◽  
Cfd Method ◽  
Yaw Angle

The hoisting forces on a 38.5m wind turbine blade in multiple positions are computed using the computational fluid dynamics (CFD) method. The computation model is constructed with the steady wind conditions, blade mesh model and the blade positions which are determined by the blade pitch angle, azimuth angle and rotor yaw angle. The maximal and minimal hoisting forces in three-dimensional coordinates are found and the corresponding pitch angle, azimuth angle and yaw angle are obtained. The change of the hoisting forces on wind turbine blades is analyzed. Suggestions are given to decrease the hoisting forces of the blade in open wind environment.

An empirical relation for cluster decay preformation probability

2014 ◽  
Vol 23 (03) ◽  
pp. 1450018 ◽  
Author(s):  
M. Balasubramaniam ◽  
N. S. Rajeswari
Keyword(s):  
Mass Number ◽  
Empirical Relation ◽  
Cluster Decay ◽  
Q Value ◽  
Mass Asymmetry ◽  
Empirical Relations ◽  
Experimental Values ◽  
Physical Quantities ◽  
Penetration Probability ◽  
Good Agreement

Empirical relations for the preformation probability of cluster decay process in terms of the Q-value, mass asymmetry (η), mass number of the emitted cluster A2 is analyzed based on the discrepancy between the calculated and experimental half-lives of the cluster emitters. For the different empirical expressions considered corresponding to different physical quantities the preformation probability for the complete binary breakup of 226 Ra is calculated and the obtained results are compared with the preformed cluster model calculation (P0( PCM )) and another calculation in which the overlapping penetration probability is treated as the preformation probability (P0(μ)). Our empirical results for the use of Q-value compare well with P0(μ). Results due to the use of Q and its powers along with the combination of mass number A2 of the cluster emitted, and mass asymmetry η, reveal that preformation factor depends strongly on Q-value rather than A2 and η. Calculated half-lives of different cluster decays for the use of empirical P0 values are found to be in good agreement with the experimental values.

Method of Attitude Measurement Based on the Geomagnetic and Gyroscope

2013 ◽  
Vol 336-338 ◽  
pp. 180-184 ◽  
Author(s):  
Li Long ◽  
He Zhang
Keyword(s):  
Pitch Angle ◽  
Measurement Accuracy ◽  
Performance Test ◽  
Detection System ◽  
Roll Angle ◽  
Angle Error ◽  
Blind Area ◽  
Trajectory Correction ◽  
Yaw Angle ◽  
Attitude Detection

The trajectory correction capability of the Simple guided munitions is directly affected by measurement accuracy of attitude angle. A gesture detection method based on geomagnetic gyro combination is proposed in this paper in order to detect the projectile flight attitude, The yaw angle of the projectile is solved by using runge-kutta algorithm with angle information of MEMS gyro. Then roll angle and pitch angle of the projectile is solved by magnetic field component of the three-axis magnetic sensor. Finally, the whole attitude detection system is installed in three-axis non-magnetic turntable to have a performance test. Experimental results show that the attitude solution results error is small. Nearby blind area, the roll angle error reduced to 5° and the pitch angle error reduced to 4°. In other locations, the roll angle error reduced to 2° and the pitch angle error reduce to 1°. The measurement accuracy increased nearly tenfold, can satisfy the trajectory correction demand of simple guidance ammunition.

Penetration Deep of Non-Deformable Projectile into Concrete Targets

2012 ◽  
Vol 446-449 ◽  
pp. 3604-3608
Author(s):  
Wei Wei Sun ◽  
Jun Yuan
Keyword(s):  
Penetration Depth ◽  
Unconfined Compressive Strength ◽  
Frictional Coefficient ◽  
Cavity Expansion ◽  
Stress Difference ◽  
Additional Mass ◽  
Depth Of Penetration ◽  
Penetration Data ◽  
The Relationship ◽  
Good Agreement

A dynamic cavity-expansion penetration model for concrete targets impacted by non-deformable projectile is developed. Based on the dynamic cavity-expansion penetration model, the equations of the final penetration depth were determined including the effect of additional mass and sliding frictional coefficient. The predicted final Penetration depth was compared with the depth of penetration data and a good agreement was achieved. The analysis indicated the additional mass was negligible compared to the mass of the projectile and independent of the striking velocity. When the friction between the concrete and the nose surface is assumed to be negligible, the final penetration depth increases slightly. The relationship between the principle stress difference at failure and unconfined compressive strength was determined by curve fitting.

Investigation of Non-Axisymmetric Endwall Contouring and 3D Airfoil Design in a 1.5 Stage Axial Turbine: Part II — Experimental Validation

2014 ◽  
Author(s):  
Jens Niewoehner ◽  
Thorsten Poehler ◽  
Peter Jeschke ◽  
Yavuz Guendogdu
Keyword(s):  
Experimental Validation ◽  
Guide Vane ◽  
Radial Profile ◽  
Mechanical Efficiency ◽  
Fast Response ◽  
Numerical Results ◽  
Inlet Guide Vane ◽  
Main Effect ◽  
Yaw Angle ◽  
Good Agreement

This paper is the second part of a two-part paper reporting on the increase in efficiency of a 1.5 stage axial test rig turbine with the use of non-axisymmetric endwalls and 3D airfoil design. Contoured endwalls were developed for the inlet guide vane separately, as well as in combination with a bowed radial profile stacking. In addition, a contour endwall was applied to the hub of the unshrouded rotor. In part I the design of the profiled endwalls and 3D airfoils is presented, as well as a detailed analysis of the steady and unsteady CFD results. Part II reports on the experimental validation of the numerical results. A distinct increase in mechanical efficiency for both new configurations in good agreement with the numerical results is observed. Additionally, performance map measurements demonstrate that the new designs are also beneficial under off-design conditions. Five- and three-hole-probes, as well as fast-response total pressure probes are used to investigate the new designs. The main effect is the homogenization of the yaw angle behind the first stator.

scholarly journals Research on Attitude Measurement Method of Special Aircraft Using Geomagnetic Sensor/Gyroscope Based on UKF

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Zhang Ping-an ◽  
Wang Wei ◽  
Gao Min ◽  
Wang Yi
Keyword(s):  
Real Time ◽  
Pitch Angle ◽  
Measurement Method ◽  
Unscented Kalman Filter ◽  
Direct Calculation ◽  
Attitude Measurement ◽  
Aircraft Flight ◽  
Simulation Results ◽  
Output Information ◽  
Yaw Angle

Based on the output information of the three-axis geomagnetic sensor and three-axis gyroscope, a mathematical model for measuring the flight attitude information of special aircraft is established, and the flight attitude of the special aircraft is calculated in real time. To improve the accuracy of calculating the flight attitude of the special aircraft, the model of the pitch and yaw angles based on the Unscented Kalman filter (UKF) is established by using the output expression of the gyroscope and geomagnetic sensor x -axis, and then the pitch angle and yaw angle obtained by filtering are brought into the geomagnetic sensor to calculate the roll angle of special aircraft in real time. The simulation results show that compared with the direct calculation of the special aircraft flight attitude angle, the combination of a geomagnetic sensor and gyroscope is more accurate after UKF processing, which verifies the effectiveness and feasibility of the attitude calculation method, and improves the accuracy of flight attitude measurement for special aircraft.

scholarly journals Optimal control in trajectory planning for a re-entry vehicle

2008 ◽  
Vol 18 (1) ◽  
pp. 1-4 ◽  
Author(s):  
Bogdan Căruntu ◽  
Romeo Negrea ◽  
Ioan Luminosu
Keyword(s):  
Optimal Control ◽  
Trajectory Planning ◽  
Pitch Angle ◽  
Attack Angle ◽  
Linear Control ◽  
Reentry Vehicle ◽  
Control Functions ◽  
Good Agreement

The objective of this paper is to establish a desired trajectory for the Alflex reentry vehicle using stepwise and linear control functions, so that the oscillations of the pitch, roll and yaw rates are minimized. For the variations of the attack angle and pitch angle we find control functions for which the computed results are in a good agreement with those recorded experimentally.

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