scholarly journals The Specification of Air-to-Air Combat Tactics Using UML Sequence Diagram

2021 ◽  
Vol 24 (6) ◽  
pp. 664-675
Author(s):  
Myunghwan Park ◽  
Jihyun Oh ◽  
Cheonyoung Kim ◽  
Hyeonju Seol
Keyword(s):  
Natural Language ◽  
High Speed ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Sequence Diagram ◽  
Natural Languages ◽  
Extended Sequence ◽  
Air Combat ◽  
Current Sequence ◽  
Uml Sequence Diagram

Air force air-to-air combat tactics are occurring at a high speed in three-dimensional space. The specification of the tactics requires dealing with a quite amount of information, which makes it a challenge to accurately describe the maneuvering procedure of the tactics. The specification of air-to-air tactics using natural languages is not suitable because of the intrinsic ambiguity of natural languages. Therefore, this paper proposes an approach of using UML Sequence Diagram to describe air-to-air combat tactics. Since the current Sequence Diagram notation is not sufficient to express all aspects of the tactics, we extend the syntax of the Sequence Diagram to accommodate the required features of air-to-air combat tactics. We evaluate the applicability of the extended Sequence Diagram to air-to-air combat tactics using a case example, that is the manned-unmanned teaming combat tactic. The result shows that Sequence Diagram specification is more advantageous than natural language specification in terms of readability, conciseness, and accuracy. However, the expressiveness of the Sequence Diagram is evaluated to be less powerful than natural language, requiring further study to address this issue.

scholarly journals Vortex flow and cavitation in diesel injector nozzles

2008 ◽  
Vol 610 ◽  
pp. 195-215 ◽  
Author(s):  
A. ANDRIOTIS ◽  
M. GAVAISES ◽  
C. ARCOUMANIS
Keyword(s):  
High Speed ◽  
Fuel Injection ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Flow Distribution ◽  
Fuel Injector ◽  
Flowing Liquid ◽  
Injection Quantity ◽  
Dimensional Reconstruction ◽  
Real Size

Flow visualization as well as three-dimensional cavitating flow simulations have been employed for characterizing the formation of cavitation inside transparent replicas of fuel injector valves used in low-speed two-stroke diesel engines. The designs tested have incorporated five-hole nozzles with cylindrical as well as tapered holes operating at different fixed needle lift positions. High-speed images have revealed the formation of an unsteady vapour structure upstream of the injection holes inside the nozzle volume, which is referred to as ‘string-cavitation’. Computation of the flow distribution and combination with three-dimensional reconstruction of the location of the strings inside the nozzle volume has revealed that strings are found at the core of recirculation zones; they originate either from pre-existing cavitation sites forming at sharp corners inside the nozzle where the pressure falls below the vapour pressure of the flowing liquid, or even from suction of outside air downstream of the hole exit. Processing of the acquired images has allowed estimation of the mean location and probability of appearance of the cavitating strings in the three-dimensional space as a function of needle lift, cavitation and Reynolds number. The frequency of appearance of the strings has been correlated with the Strouhal number of the vortices developing inside the sac volume; the latter has been found to be a function of needle lift and hole shape. The presence of strings has significantly affected the flow conditions at the nozzle exit, influencing the injected spray. The cavitation structures formed inside the injection holes are significantly altered by the presence of cavitation strings and are jointly responsible for up to 10% variation in the instantaneous fuel injection quantity. Extrapolation using model predictions for real-size injectors operating at realistic injection pressures indicates that cavitation strings are expected to appear within the time scales of typical injection events, implying significant hole-to-hole and cycle-to-cycle variations during the corresponding spray development.

Computation of Rigid-Body Rotation in Three-Dimensional Space From Body-Fixed Linear Acceleration Measurements

1979 ◽  
Vol 46 (4) ◽  
pp. 925-930 ◽  
Author(s):  
N. K. Mital ◽  
A. I. King
Keyword(s):  
Rigid Body ◽  
High Speed ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Angular Acceleration ◽  
Linear Acceleration ◽  
Field Measurements ◽  
Moving Frame ◽  
Accelerometer Data ◽  
Hypothetical Data

The angular acceleration of a rigid body with respect to a body-fixed (moving) frame can be reliably computed from nine acceleration field measurements. Noncommutativity of finite rotations causes computational problems during numerical integration to obtain the transformation matrix, especially when the rotation is three-dimensional and there are errors in the measured linear accelerations. A method based on the orientation vector concept is formulated and tested against hypothetical data. The rigid-body rotations computed from linear accelerometer data from impact acceleration tests are compared against those obtained from three-dimensional analysis of high speed movie films.

Experimental and numerical analyses of wedge effects on the rooster tail and porpoising phenomenon of a high-speed planing craft in calm water

2019 ◽  
Vol 233 (13) ◽  
pp. 4637-4652 ◽  
Author(s):  
Sayyed Mahdi Sajedi ◽  
Parviz Ghadimi ◽  
Mohammad Sheikholeslami ◽  
Mohammad A Ghassemi
Keyword(s):  
High Speed ◽  
Degrees Of Freedom ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Scale Model ◽  
Test Cases ◽  
Planing Craft ◽  
Calm Water ◽  
Space Discretization ◽  
Good Agreement

This paper presents experimental and numerical investigation of stability and rooster tail of a mono-hull high-speed planing craft with a constant deadrise angle. Initially, a one-fifth scale model was tested in a towing tank, which showed porpoising phenomenon at 8 m/s (equal to the speed of sailing). Subsequently, two wedges of 5 and 10 mm heights, based on the boundary layer calculations, were mounted on the aft section of the planing hull. These wedges were shown to increase the lift at the aft section. These experiments were carried out at different speeds up to 10 m/s in calm water. The experimental results indicated that the installed wedges reduced the trim, drag, and the elapsed time for reaching the hump peak, and also eliminated the porpoising condition. All these test cases were also numerically simulated using Star CCM+ software. The free surface was modeled using the volume of fluid scheme in three-dimensional space. The examined planing craft had two degrees of freedom, and overset mesh technique was used for space discretization. The obtained numerical results were compared with experimental data and good agreement was displayed in the presented comparisons. Ultimately, the effect of the wedge on the rooster tail behind the planing craft was studied. The results of this investigation showed that by decreasing the trim at a constant speed, the height of the generated wake profile (rooster tail) behind the craft decreases, albeit its length increases.

Dynamic Modeling and Vibration Response Simulation for High Speed Rolling Ball Bearings With Localized Surface Defects in Raceways

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Linkai Niu ◽  
Hongrui Cao ◽  
Zhengjia He ◽  
Yamin Li
Keyword(s):  
High Speed ◽  
Degrees Of Freedom ◽  
Surface Defects ◽  
Dimensional Space ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Hertzian Contact ◽  
Ball Bearings ◽  
Rolling Ball ◽  
Vibration Responses

A dynamic model is developed to investigate vibrations of high speed rolling ball bearings with localized surface defects on raceways. In this model, each bearing component (i.e., inner raceway, outer raceway and rolling ball) has six degrees of freedom (DOFs) to completely describe its dynamic characteristics in three-dimensional space. Gyroscopic moment, centrifugal force, lubrication traction/slip between bearing component are included owing to high speed effects. Moreover, local defects are modeled accurately and completely with consideration of additional deflection due to material absence, changes of Hertzian contact coefficient and changes of contact force directions due to raceway curvature variations. The obtained equations of motion are solved numerically using the fourth order Runge–Kutta–Fehlberg scheme with step-changing criterion. Vibration responses of a defective bearing with localized surface defects are simulated and analyzed in both time domain and frequency domain, and the effectiveness of fault feature extraction techniques is also discussed. An experiment is carried out on an aerospace bearing test rig. By comparing the simulation results with experiments, it is confirmed that the proposed model is capable of predicting vibration responses of defective high speed rolling ball bearings effectively.

Experimental investigation of cage motions in an angular contact ball bearing

2017 ◽  
Vol 231 (8) ◽  
pp. 1041-1055 ◽  
Author(s):  
Baogang Wen ◽  
Hongjun Ren ◽  
Hao Zhang ◽  
Qingkai Han
Keyword(s):  
Experimental Investigation ◽  
High Speed ◽  
Ball Bearing ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Axial Loads ◽  
Angular Contact Ball Bearing ◽  
Radial Forces ◽  
External Loads

The commonly known effects of both the rotating speeds and external loads on the bearing dynamics or life behaviors are mostly caused by its cage dynamics, because of the complicated contact and collision interactions between the cage and other parts such as the inner or outer rings and balls. In this paper, experimental investigation of dynamic motions of a cage is carried out under various rotating speeds and external loads in a ball bearing. On a bearing test rig, the cage motions in axial and radial directions are measured by use of eddy transducers installed inside the bearing house and the subpanel. Then the measured results are analyzed by fast Fourier transform and compared at different operating conditions including rotating speeds, axial and radial forces, or moments. The three-dimensional space motions of the cage are also constructed to illustrate its different modes. Results reveal that the cage motions are typically periodic in the three directions. The motion frequencies consist of the cage rotating frequency and its multi-frequency, the inner ring rotating frequency, and also some combination frequencies of the cage and inner ring. The obtained characteristic frequencies of the cage motion in axial are similar to that in radial, but different in the variety of amplitudes under the same operating conditions. The increment of rotating speeds and axial loads of the bearing gradually make the whirl trajectories of the cage mass center regular, and enlarge its whirl radii. Instead, the whirl trajectories change from well-defined patterns to complicated ones, and its whirl radii decrease on increasing the radial loads and moments of the bearing. All the obtained experimental results are useful references for dynamic design and life prediction of high-speed and low-load bearings commonly used in many machines.

scholarly journals Propulsive design principles in a multi-jet siphonophore

2018 ◽  
Author(s):  
Kelly R. Sutherland ◽  
Sean P. Colin ◽  
John H. Costello ◽  
Brad J. Gemmell
Keyword(s):  
High Speed ◽  
Swimming Performance ◽  
Dimensional Space ◽  
Fluid Motion ◽  
Three Dimensional ◽  
Flow Parameters ◽  
Image Velocimetry ◽  
Summary Statement ◽  
High Pressure Region ◽  
Three Dimensional Space

AbstractCoordination of multiple propulsors can provide performance benefits in swimming organisms. Siphonophores are marine colonial organisms that orchestrate the motion of multiple swimming zooids for effective swimming. However, the kinematics at the level of individual swimming zooids (nectophores) have not been examined in detail. We used high speed, high resolution microvideography and particle image velocimetry (PIV) of the physonect siphonophore, Nanomia bijuga, to study the motion of the nectophores and the associated fluid motion during jetting and refilling. The integration of nectophore and velum kinematics allow for a high-speed (maximum ~1 m s−1), narrow (1-2 mm) jet and rapid refill as well as a 1:1 ratio of jetting to refill time. Overall swimming performance is enhanced by velocity gradients produced in the nectophore during refill, which lead to a high pressure region that produces forward thrust. Generating thrust during both the jet and refill phases augments the distance travelled by 17% over theoretical animals, which generate thrust only during the jet phase. The details of velum kinematics and associated fluid mechanics elucidate how siphonophores effectively navigate three-dimensional space and could be applied to exit flow parameters in multijet underwater vehicles.Summary statement:Colonial siphonophores produce high speed jets and generate forward thrust during refill using a flexible velum to achieve effective propulsion.

scholarly journals Visually targeted reaching in horse-head grasshoppers

2012 ◽  
Vol 279 (1743) ◽  
pp. 3697-3705 ◽  
Author(s):  
Jeremy E. Niven ◽  
Swidbert R. Ott ◽  
Stephen M. Rogers
Keyword(s):  
High Speed ◽  
Visual Cues ◽  
Motion Parallax ◽  
Dimensional Space ◽  
Body Position ◽  
Motor Pattern ◽  
Three Dimensional ◽  
Visual Inputs ◽  
Sensorimotor Transformations ◽  
Specific Object

Visually targeted reaching to a specific object is a demanding neuronal task requiring the translation of the location of the object from a two-dimensionsal set of retinotopic coordinates to a motor pattern that guides a limb to that point in three-dimensional space. This sensorimotor transformation has been intensively studied in mammals, but was not previously thought to occur in animals with smaller nervous systems such as insects. We studied horse-head grasshoppers (Orthoptera: Proscopididae) crossing gaps and found that visual inputs are sufficient for them to target their forelimbs to a foothold on the opposite side of the gap. High-speed video analysis showed that these reaches were targeted accurately and directly to footholds at different locations within the visual field through changes in forelimb trajectory and body position, and did not involve stereotyped searching movements. The proscopids estimated distant locations using peering to generate motion parallax, a monocular distance cue, but appeared to use binocular visual cues to estimate the distance of nearby footholds. Following occlusion of regions of binocular overlap, the proscopids resorted to peering to target reaches even to nearby locations. Monocular cues were sufficient for accurate targeting of the ipsilateral but not the contralateral forelimb. Thus, proscopids are capable not only of the sensorimotor transformations necessary for visually targeted reaching with their forelimbs but also of flexibly using different visual cues to target reaches.

scholarly journals Dynamic Visual Measurement of Driver Eye Movements

Sensors ◽  
2019 ◽  
Vol 19 (10) ◽  
pp. 2217 ◽  
Author(s):  
Jin Zhang ◽  
Ze Yang ◽  
Huaxia Deng ◽  
Huan Yu ◽  
Mengchao Ma ◽  
...  
Keyword(s):  
High Speed ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Visual Fatigue ◽  
High Definition ◽  
Robust Algorithms ◽  
Visual Measurement ◽  
New Approach ◽  
The Face ◽  
Image Acquisition System

Vibrations often cause visual fatigue for drivers, and measuring the relative motion between the driver and the display is important for evaluating this visual fatigue. This paper proposes a non-contact videometric measurement method for studying the three-dimensional trajectories of the driver’s eyes based on stereo vision. The feasibility of this method is demonstrated by dynamic calibration. A high-speed dual-camera image acquisition system is used to obtain high-definition images of the face, and the relative trajectories between the eyes and the display are obtained by a set of robust algorithms. The trajectories of the eyes in three-dimensional space are then reconstructed during the vehicle driving process. This new approach provides three-dimensional information and is effective for assessing how vibration affects human visual performance.

scholarly journals A Piecewise Hysteresis Model for a Damper of HIS System

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Kaidong Tian ◽  
Bangji Zhang ◽  
Nong Zhang ◽  
Xuhui Liu ◽  
Jinchen Ji
Keyword(s):  
High Speed ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Hysteresis Phenomenon ◽  
Hysteresis Model ◽  
Low Speed ◽  
Proposed Model ◽  
Velocity Characteristic ◽  
Force Velocity ◽  
Three Dimensional Space

A damper of the hydraulically interconnected suspension (HIS) system, as a quarter HIS, is prototyped and its damping characteristic is tested to characterize the damping property. The force-velocity characteristic of the prototype is analyzed based on a set of testing results and accordingly a piecewise hysteresis model for the damper is proposed. The proposed equivalent parametric model consists of two parts: hysteresis model in low speed region and saturation model in high speed region which are used to describe the hysteresis phenomenon in low speed and nonhysteresis phenomenon in high speed, respectively. The parameters of the model are identified based on genetic algorithm by setting the constraints of parameters according to their physical significances and the corresponding testing results. The advantages of the model are highlighted by comparing to the nonhysteresis model and the permanent hysteresis model. The numerical simulation results are compared with the testing results to validate the accuracy and effectiveness of the proposed model. Finally, to further verify the proposed model’s wide applicability under different excitation conditions, its results are compared to the testing results in three-dimensional space. The research in this paper is significant for the dynamic analysis of the HIS vehicle.

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