Dissertations / Theses on the topic 'Trajectory of projectiles'

Afin d'atteindre leur cible, les projectiles guidés d'artillerie nécessitent d'être dotés d'un dispositif de pilotage. Des surfaces de contrôle déployables et orientables sont donc nécessaires. Toutefois, le montage de gouvernes ajustables sur une ogive est une tâche mécaniquement ardue. En effet, lors du tir effectué par canon, l'équipement de bord subit une accélération significative, ce qui implique que des liaisons mécaniques particulièrement robustes doivent être conçues entre les ailettes et le corps. Cette technologie est bien maîtrisée lorsqu'elle est employée sur des projectiles de gros calibre, mais devient bien plus compliquée quand elle doit être adaptée pour être intégrée dans des petits ou moyens calibres. Néanmoins, dans des conditions de vol supersonique, des ondes de choc qui interagissent avec des surfaces solides sont susceptibles de considérablement modifier la distribution de pression. Ce principe a permis d'imaginer une méthode alternative de pilotage de projectiles supersoniques en exploitant des ondes de choc générées au moyen de petites perturbations créées à partir d'un micro-actionneur de forme cylindrique, aussi appelé micro-plot. Comme les forces de portance exercée sur un corps sont essentiellement dues à une pression appliquée sur de grandes surfaces, il a été choisi de se baser sur une configuration stabilisée par empennage. En vue de simplifier l'étude, le travail a été effectué sur un projectile académique de référence bien connu appelé le Basic Finner.Des expériences ont tout d'abord été effectuées dans la soufflerie supersonique de l'ISL sur une plaque plane comportant un plot et deux ailettes verticales. Ces mesures ont permis de valider la capacité de simulations numériques stationnaires RANS à prédire à la fois la distribution pariétale de la pression que génère un tel actionneur et le champ de vitesse de l'écoulement dans son voisinage. Les distributions de pression et de vitesse ont été mesurées en utilisant des méthodes optiques appelés Pressure Sensitive Paints (PSP) et Particle Image Velocimetry (PIV) afin d'être comparés avec les résultats de la CFD. Une étude paramétrique a ensuite été menée en se basant exclusivement sur ces simulations RANS. Ces calculs ont permis de déterminer l'emplacement optimal pour lequel le plot est le plus efficace sur toute l'enveloppe de vol du projectile. A partir de cette position optimale, deux configurations spécifiques ne générant aucun moment de roulis ont été étudiées numériquement et comparés en termes d'efficacité. En utilisant les coefficients aérodynamiques résultants de ce travail, des simulations de trajectoires à 6 degrés de liberté (6-DOF) ont été réalisées avec le code de BALCO (OTAN). Celles-ci ont permis de déterminer la déviation potentielle qui peut être obtenue sur une des deux configurations retenues en employant un tel micro-actionneur. Ces simulations 6-DOF ainsi que l'effet de du plot sur le projectile ont enfin été validés lors d'une campagne d'essai en vol libre qui a eu lieu sur le champ de tir de l'ISL
In order to reach their target, guided artillery projectiles need some steering capability. Folding and adjustable control surfaces are thus necessary. However, mounting adjustable rudders on a shell is a difficult task, mechanically speaking. Indeed, during the gun launch, the onboard equipment undergoes significant acceleration so that robust mechanical joints have to be designed between the rudders and the body. This technique performs very well on large-caliber projectiles, but becomes more complicated when it has to be embedded in small- or medium-caliber ones. Nevertheless, under supersonic flight conditions, shock waves interacting with solid surfaces are likely to strongly modify the pressure distribution. This principle made it possible to imagine a way of steering small-caliber vehicles using shock waves generated by means of small disturbances created by a cylindrical-shaped micro-actuator, also called micro-pin. As lift forces exerted on a body are mainly due to the pressure applied to large surfaces, a finned configuration has been chosen. To simplify the study, the work has been conducted on the Basic Finner, a well known academic reference projectile.Experiments were first performed in the ISL supersonic wind tunnel on a flat plate on which a pin and two vertical projectile-like fins were mounted in order to validate the capability of steady RANS numerical simulations to predict both the pressure footprint of such an actuator and the flow velocity in its vicinity. Pressure and velocity distributions have been measured by using optical methods called Pressure-Sensitive Paint (PSP) and Particle Image Velocimetry (PIV) in order to be compared with the calculation results. A parametric study was then conducted with these RANS simulations so that the optimum location for which the pin is the most effective over the complete flight envelope of the projectile could be determined. Using this optimum position two specific no-roll momentum configurations were studied numerically and compared in terms of effectiveness. By using the aerodynamic coefficients resulting from this work, 6-Degree-Of-Freedom (6-DOF) trajectory simulations were performed with the NATO BALCO code on one of these configurations in order to determine the potential deviation which can be obtained with such an actuator. These 6-DOF simulations as well as the pin effect on the projectile could finally be validated during a free-flight campaign that took place at the ISL open-range testing site

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This work aims to address some aspects of Niccolò Tartaglia's (1500-1556) different arguments on the trajectories of projectiles. On one hand, at Nova Scientia (1537), the author explained that the trajectories were composed by two straight lines and a circular arc; on the other, at Quesiti et Inventioni Diverse (1546), the same trajectories were presented only as curves. These two different approaches to the trajectory of projectiles suggested to some historians that Tartaglia had changed his mind, leaving, in a way, his old beliefs. Thus, based on original documents, this paper seeks to resume Tartaglia arguments in order to understand the reasons which would have led him to change his approaches in those two works. Despite other factors, we present evidence that Tartaglia had, around 1540, come in contact with works that had almost none circulation before. With this in mind, our work provides evidence that there is some continuity between the arguments of Tartaglia on the trajectories in these two works
Este trabalho tem por objetivo tratar alguns aspectos das diferentes argumentações de Niccolò Tartaglia (1500-1556) sobre as trajetórias dos projéteis. Na Nova Scientia (1537), as trajetórias seriam compostas por duas retas e um arco de circunferência. Já nos Quesiti et Inventioni Diverse (1546), elas são apresentadas completamente curvas. Esses dois enfoques diferentes dados ao tema sugeriram a alguns historiadores que Tartaglia teria mudado de ideia, abandonando, de certa maneira, suas antigas convicções. Desse modo, baseado em documentos originais, este trabalho busca retomar os argumentos de Tartaglia de modo a compreendermos as razões que o teriam levado a dar dois diferentes enfoques nas duas obras. Dentre outros fatores, apresentamos indícios de que Tartaglia passou a contar, por volta de 1540, com obras anteriormente desconhecidas e que pouco circulavam até então. Tendo isso em vista, nosso trabalho fornece indícios de que podemos observar certa continuidade entre as argumentações de Tartaglia sobre as trajetórias nessas duas obras

The thesis traces the history of missile aerodynamic prediction methods and defines the aerodynamic requirements for the subsonic free-flight projectiles configurations under consideration. Different types of trajectory model are described with the aerodynamic input requirement being analysed. Methods of generating the required aerodynamic data for the trajectory models are discussed emphasising the aerodynamic models capabilities, weaknesses and ease of use. The method of masses aerodynamic prediction method is defined, highlighting the adaptations to the method that were carried out to generate the aerodynamic stability data required for subsequent projectile trajectory analysis. An assessment of the sensitivity and accuracy of the simulated data is carried out using experimental flight trial data on different projectile configurations. Finally, using the simulation models developed in previous chapters, a parametric analysis is carried out on different projectile configurations to optimise the trajectory performance.

L’intensification des combats en milieu urbains pousse les industriels de l’armement terrestre à développer des systèmes d’armes intégrant des dispositifs de correction de trajectoire. Le déploiement de tels dispositifs au cours du vol d’un projectile d’artillerie doit permettre de réduire l’erreur de dispersion afin de limiter au maximum les risques de dommages collatéraux. L’enjeu réside ici dans le développement d’un dispositif adapté aux conditions de vol d’un projectile gyrostabilisé. Un spoiler isolé, supposé monté sur une bague libre en rotation, est identifié comme le moyen de contrôle le plus adapté. L’objet de ces travaux consiste à développer un algorithme d’optimisation des caractéristiques géométriques d’un tel dispositif et de démontrer qu’il possède l’autorité suffisante pour générer une modification de la portée ainsi que de la déviation latérale du projectile. D’une part un réseau de neurones modélise les variations des coefficients aérodynamiques du spoiler à partir de résultats de simulations RANS. D’autre part, la modélisation par kriging des fonctions objectifs et contraintes tire avantage de l’estimation de l’erreur de modélisation. Ceci permet de définir des critères d’enrichissement assurant un compromis entre exploration et exploitation du domaine défini par l’ensemble des paramètres géométriques. L’application de l’algorithme d’optimisation au dimensionnement du spoiler a permis d’identifier une configuration géométrique optimale satisfaisant les objectifs de l’étude en termes de correction de trajectoire. Des simulations ZDES sur cette configuration particulière ont été réalisées dans le but de constituer un niveau de fidélité supérieur aux évaluations RANS des coefficients aérodynamiques. Elles donnent également lieu à une caractérisation physique des modifications de l’écoulement de culot engendrées par la présence du spoiler. Une campagne d’essais en soufflerie permet de valider la démarche méthodologique développée dans ces travaux et ouvre des perspectives pour de futurs travaux concernant l’inclusion de données expérimentales dans une base de données numérique dans le cadre de méta-modèles multi-niveaux de fidélité
The intensification of urban combat encourages the industrials of terrestrial armament to develop new weapon systems equipped with trajectory modification devices. Deploying these devices during the projectile flight would allow reducing the scattering error in order to narrow the collateral damage. The challenge lies in the development of a device adapted to the flight conditions of a spin-stabilized projectile. An isolated spoiler, installed on a rotatable ring, is chosen as the most adapted control device. This work consists in developing an optimization algorithm for the geometrical parameters of the spoiler and to demonstrate that it is possible to modify concurrently the range and lateral deviation of the projectile. On one hand a neural network model the variations of the aerodynamic coefficients from RANS calculations. On the other hand, the kriging modeling of the objective and constraint functions benefits from the estimation of the modeling error. This allows defining enrichment criteria ensuring a tradeoff between exploration and exploitation of the geometrical domain. The optimization of the spoiler geometrical parameters leads to the identification of an optimal configuration able to achieve the course corrections abilities targeted. ZDES simulations on this particular configuration have been achieved to form a new fidelity level in addition to the RANS evaluations of the aerodynamic coefficients. These simulations lead to a physical characterization of modifications of the boat-tail flow induced by the presence of the spoiler. A wind tunnel campaign provides a validation step to the optimization methodology developed and offers promising perspectives for future work in terms of experimental data inclusion in a numerical database through multi-level surrogate modeling

Respiration introduces large tumor motion in the thoracic region which influences treatment outcome for lung cancer patients. Tumor motion management techniques require characterization of temporal tumor motions because tumor motion varies patient to patient, day to day and cycle to cycle. This work develops a markerless algorithm to estimate 3 dimensional (3D) lung-tumor trajectories on free breathing cone beam computed tomography (CBCT) projections, which are 2 dimensional (2D) sequential images rotating about an axis and are used to reconstruct 3D CBCT images. A gold standard tumor trajectory is required to guide the algorithm development and estimate the tumor detection accuracy for markerless tracking algorithms. However, a sufficient strategy to validate markerless tracking algorithms is lacking. A validation framework is developed based on fiducial markers. Markers are segmented and marker trajectories are xiv obtained. The displacement of the tumor to the marker is calculated and added to the segmented marker trajectory to generate reference tumor trajectory. Markerless tumor trajectory estimation (MLTM) algorithm is developed and improved to acquire tumor trajectory with clinical acceptable accuracy for locally advanced lung tumors. The development is separate into two parts. The first part considers none tumor deformation. It investigates shape and appearance of the template, moreover, a constraint method is introduced to narrow down the template matching searching region for more precise matching results. The second part is to accommodate tumor deformation near the end of the treatment. The accuracy of MLTM is calculated and compared against 4D CBCT, which is the current standard of care. In summary, a validation framework based on fiducial markers is successfully built. MLTM is successfully developed with or without the consideration of tumor deformation with promising accuracy. MLTM outperforms 4D CBCT in temporal tumor trajectory estimation.

Thesis (Ph. D.)--University of California, San Diego, 2010.
Title from first page of PDF file (viewed June 23, 2010). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (leaves 129-150).

Dans cette thèse, nous présentons une étude algorithmique et numérique concernant la méthode de trajectoire centrale appliquée au problème de complémentarité linéaire considéré comme une formulation unificatrice de la programmation linéaire et de la programmation quadratique convexe. Puis, nous proposons deux variantes intéressantes, l'une de trajectoire centrale et l'autre de type projectif avec linéarisation, pour minimiser une fonction convexe différentiable sur un polyèdre. Les algorithmes sont bien définis et les résultats théoriques correspondants sont établis
In this thesis, we present an algorithmically and numerical study concerning the central path method for linear complementarity problem wich is considered as an unifying framework of linear and quadratic programming. Then, we propose two intersting variants namely the central path and the projective with linearization methods for minimizing a convex differentiable function on a polyhedral set. The algorithms are well defined and the corresponding theoretical results are established

Robots manipulateurs sont couramment utilisés pour la projection thermique, qui peuvent être programmés de deux façons : par apprentissage et par la programmation hors-ligne. La programmation par apprentissage ne peut pas garantir la qualité de revêtements, en particulier pour les pièces de forme complexe. La technologie de la programmation hors-ligne est une bonne solution, en utilisant le fichier CAO de la pièce à revêtir. Le but de cette étude est de développer une trousse à outil - Thermal Spray Toolkit (TST) sous RobotStudio™ 5 (ABB), un logiciel de programmation hors-ligne, pour générer la trajectoire adaptée à l'application de projection thermique en fonction de la forme de la pièce et des paramètres cinématiques tels que la distance de projection, l'orientation normal à la surface, le débordement, le pas de balayage etc. Cela résout les difficultés de génération de la trajectoire adaptée à la projection thermique sur la pièce complexe sous RobotStudio™. En outre, deux méthodes d'amélioration de la trajectoire sont proposées pour maintenir la vitesse du CDO après les analyses. Les simulations et les essais ont prouvé que ces deux méthodes peuvent améliorer efficacement la stabilité de la vitesse du CDO ainsi que la qualité du revêtement. A la fin, l'axe externe rotatif a été appliqué en projection thermique et la programmation d'axe externe automatique a été intégrée également dans le TST. Les trajectoires verticale et horizontale ont été générées et analysées sur une pièce qui nécessite de l'utilisation d'un axe externe. Les simulations et les essais ont été réalisés pour ces différents programmes, ils ont montré que la trajectoire verticale a donné de meilleurs résultats que la trajectoire horizontale.

碩士
逢甲大學
航太與系統工程所
98
The movement of projectile in airflow field frequently occurs in our daily life. The scale of this phenomenon may be as small as the tiny particles moving in airflow and as big as the projectiles of any shape moving in the flow field. In this research, computational fluid dynamics software Fluent 6.3.26 is employed. In accordance with different rotational speed, initial velocity and direction of rotation, the dynamic trajectory of projectile in airflow were predicted. In this study, dynamic mesh technique and κ-ε turbulence model provided by Fluent were used in the simulation of interactions between projectiles and the surrounding airflow. According to the transient displacement of the projectile subjected to forces, variation of pressure in surrounding airflow, recirculation phenomena and dynamic trajectory of projectiles were analyzed. It was found that the pressure difference between the upper and lower surfaces of projectiles with different rotation speed affects their descent distances. With increasing of rotation speed, shorter distance is descended. The flight paths of projectiles investigated are parabolic trajectories.

Wildfires are a devastating source of human and environmental loss, and the available means to combat them in their early stages can be improved. With the aid of Unmanned Aerial Systems and FEB (Fire-extinguishing balls), wildfires’ early stages might be suppressed while keeping human lives safe and firefighters risk-free. Considering the use of a fixed wing Unmanned Aircraft Vehicle to launch the fire-extinguishing projectile, launching the FEB as it is, without any modification, does not seem to be the best available option, with problems ranging from difficulty in predicting its trajectory to the possible bad impact performance, with the possibility of the FEB rolling away from the target as it lands. Therefore, three other configurations for the projectile with FEB as its basis were studied, all of them utilizing fins for the means of stability. These configurations differed in terms of tail design attached to the FEB: one is a tube, the other a tangential cone, and the other a symmetrical NACA airfoil revolved around its axis. Their aerodynamic static coefficients were obtained through CFD (computational fluid dynamics), while the dynamic ones were obtained through analytical expressions. Using an implemented 6-DOF (degrees of freedom) model, 17 trajectories were studied for each of these configurations. Other analyses were carried out, as the consideration of the influence of wind turbulence, consideration of a fourth configuration with double the area of the fins, and asserting the importance of the consideration of the dynamic coefficients while testing different values for some of these coefficients. Regarding the FEB-projectile configurations, CFD results suggest that the tube configuration has a transient behavior in the tested speeds, and that the tangential cone is a very suitable way of streamlining the FEB in these range of speeds, with no considerable difference to the NACA tail configuration. Trajectory results highlight the importance of considering the mean wind speed and direction, the importance of obtaining an appropriate estimate of the wind turbulence, and the importance of the dynamic coefficients for the full aerodynamic characterization of the projectile, concretely for its stability and attitude results. Ultimately, between the tested configurations, the best candidate is the cone tail configuration, for its simplicity in construction and performance in the trajectories.
Os incêndios florestais são uma fonte devastadora de custos humanos e ambientais, e os meios disponíveis para combater as suas fases iniciais poderão ser melhoradas. Com o auxílio de sistemas de aeronaves não-tripuladas e de FEB (bolas extintoras), os incêndios florestais poderão ser extintos nas suas fases iniciais, mantendo vidas humanas livres de risco. Considerando o uso de uma aeronave não tripulada de asa fixa para lançar o projétilextintor, lançar a bola extintora tal como é não aparenta ser a melhor opção, sendo alguns dos problemas relacionados com o seu lançamento a dificuldade em prever a sua trajetória e um possível mau desempenho no impacto, com a possibilidade da bola rolar para longe do seu alvo. Assim, três configurações para o projétil extintor que tem a FEB como base foram estudados, todos eles utilizando empenagens como forma de estabilização. As configurações diferem em termos da cauda acoplada à FEB: uma delas é um tubo, outra um cone tangencial, e outra um perfil NACA simétrico girado em torno do seu eixo. Os coeficientes aerodinâmicos estáticos foram obtidos através de CFD (dinâmica de fluidos computacional), enquanto que os dinâmicos foram obtidos por expressões analíticas. Implementando um modelo de trajetória 6-DOF (6 graus de liberdade) 17 trajetórias foram estudadas para cada uma das configurações. Outras análises foram realizadas, como a relevância na trajetória da turbulência do vento, a consideração de uma quarta configuração com o dobro da área das empenagens, e a determinação da importância dos coeficientes dinâmicos, testando vários valores para alguns dos coeficientes. Em relação às configurações do projétil testadas, os resultados CFD sugerem que a configuração com o tubo possui um comportamento transiente nas velocidades testadas, e que o cone tangencial é uma forma bastante eficaz de tornar a esfera mais aerodinâmica, nesta gama de velocidades não havendo uma diferença considerável entre esta configuração e a configuração com a cauda NACA. Os resultados das trajetórias destacam a importância da consideração da velocidade e orientação do vento médio, a importância de obter uma estimativa apropriada para a turbulência do vento, e a relevância dos coeficientes dinâmicos para a caracterização aerodinâmica completa do projétil, concretamente em relação à estabilização e atitude. Entre as configurações testadas, o melhor candidato é a configuração com cauda em cone, pela sua simplicidade de construção e desempenho nas trajetórias.

碩士
國立成功大學
工程科學系
103
The main purpose of this thesis is to study a multi-camera visual tracking system, which guides an omnidirectional mobile robot to catch a projectile. In the vision tracking system, two image sensors are used to provide stereo vision. The vision system is able to track the throwing projectile according to it’s color information. After the position of the projectile has been determined by Kalman filter, the omnidirectional mobile robot moves to the point of fall which is sent to the robot via a wireless communication module. Through simulation and experiments, this thesis has shown the feasibility of the designed system. The projectile can be truly tracked by the active stereo vision system, and the omnidirectional mobile robot can also catch the projectile.

碩士
國立成功大學
航空太空工程學系
86
The work investigates the trojectory and effects of a projectile by aerodynamics, and caculates the displacement and distribution when they are thrown out from an aircraft. The projectile is complicated and unregular on it' s configuration The flow field could be observed by the experiment of water channel and the results obtained can suppose that the drag is increasing or decreasing by reason of cofiguration. 　　The flow distribution could be observed by the experiment of water channel. The magnitude of force and moment of the projectile can be arrived by the experiment of wind tunnel. The study will investigate the theory of motion and aerodynamics of the projectile and write the program. 　　Finally, taking the initial condition of the projectile with 200 and 500 meters height and 3.8 kiograms weight and velocity 40 i+10 j m/s into the program to caculate the trajectory and Euler.

碩士
國立勤益科技大學
電機工程系
105
Projectile trajectory estimation systems are often used in military defense such as missiles, rockets and other parabolic trajectory prediction. However, they usually use radar or sonar detection methods, which can only provide local and passive information. When a human takes a flying projectile, fast he looks attentively at the projectile to estimate the object flight path, and then takes the object. In this paper, we propose projectile trajectory estimation systems based on stereo vision. Two parallel network cameras simulate the human eyes. The stereo vision algorithm is used to capture the target from images. The target’s images are calculated with SAD (Sum of Absolute Difference) algorithm for image matching to calculate the target’s position and height in images. Kalman Filter (KF) and Unscented Kalman Filter (UKF) are used to estimate the trajectory and the landing position of the projectile, when it flies in the space. Experiments are carried out in different illumination background, different volume and weight of projectiles. Experiments of projectile trajectory estimation by KF and UKF correspond closely to the real trajectory. The projectile trajectory estimations by UKF correspond more closely to the real trajectory than those by KF.

碩士
中原大學
機械工程研究所
92
Abstract This study model the sabot discard projectile body by SolidWorks software and simulate the process of all dynamic behavior of the projectile body by ADAMS software. The process is moderated landed from shooting, shelling, and the parachute’s deceleration. Sabot discard flight of dynamic simulation regards as 3D rigid body structure. Shelled dynamics and aerodynamics, derive out the equation of the projectile body which is shooting, shelling, and parachute’s landing, and receive the lift and drag coefficients, and put them into ADAMS , and finish the simulated flight of the projectile body. This study discusses the projectile body’s influence of wind velocity and initial velocity and shooting angle and sabot discard force and escape time on the projectile body, and the simulation of the expanded antenna mechanism. By various kinds of situations of ADAMS simulation predict the flight route and position of the projectile body.

碩士
國防大學理工學院
機械工程碩士班
102
Mortar is a tail fin-stabilized projectile which has the characteristics of simple structure, light, agility, and wide area of firepower. In modern warfare it is also a mainstream and indispensable weapon for the Army's ground battles. Many countries currently are still doing lots of researches on the improvement of mortar performance. The purpose of this study is to investigate the aerodynamic performance of the new type of 81mm mortar (with lengthened tail pipe). The thesis uses the computational fluid dynamic (CFD) techniques combined with wind tunnel experiments to study the aerodynamic performance of the new 81mm mortar with different number of tail fins (4, 6, and 8 fins: referred as 81_4FIN, 81_6FIN, and 81_8FIN). For the experiments, the projectile model is test in a low-speed wind tunnel, and then the Karman-Tsien Rule formula is used for converting the aerodynamic data measured from low speed wind tunnel experiments into subsonic compressible flow data. In the CDF numerical simulations, the calculation grids are built by using ICEM and the solver used is ANSYS 12.1-FLUENT. The accuracy of CFD predictions is validated with the converted subsonic data obtained from low-speed wind tunnel experiments. Then, the relevant aerodynamic parameters of the new mortar are obtained from CFD simulations. Based on these data, the projectile flight trajectory is predicted from a projectile trajectory prediction program which is developed according to the basic flight trajectory theory. The software of 6 DoF (six degrees of freedom) module of MATLAB/Simulink is also employed to simulate projectile flight trajectory in this study. The CFD predictions show that: 81_6FIN has better aerodynamic performance; 81_4FIN has higher lift to drag ratio but its stability is poor due to less number of tail fins; 81_8FIN has better stability but it has lower lift to drag ratio due to greater drag produced by larger number of tail fins and less lift affected by fin-to-fin interference effect. The flight trajectory simulation results indicate that, the projectile trajectory prediction program is able to accurately simulate the two-dimensional trajectory with error under 5% comparing with the data from firing table. In addition, the two-dimensional trajectory is also reasonably predicted by using the MATLAB/Simulink software. The results show the trend in accord with the general physical characteristics of the trajectory. As for the three-dimensional trajectory prediction, it has had preliminary results already.

碩士
國立臺灣大學
造船及海洋工程學研究所
90
The subject of this paper is to study the trajectory of the projectile penetrating the air-water interface and analysis its stability experimentally. In theoretical part, firstly, we derive the fundamental of the experiment and the dynamic relation between the model and projected projectile. Secondly, the theoretical trajectory of the center of gravity of the model projectile is computed. In experimental part, the projectile is projected by air pressure and free fall. The experiment is conducted in NTU-NAOE towing tank. Two CCD cameras were setup, one is above and the other is under water surface, respectively, to record the trajectory of the projectile. After analyzed the trajectory of the center of gravity, pitch angle, and attack angle, the result was compared with the computed data Generally, from the comparison and the experiment result we find that the projectile is stable when the projectile angle is 20, 25, and 30 degree, and the speed is within 4~10 m/s.

碩士
國防大學理工學院
機械工程碩士班
105
This paper combines computational fluid mechanics (CfD) method and Fortran trajectory simulation program to explore the aerodynamic characteristics and trajectory simulation of the new type 81 mm projectile in different type of fuze (4 control canard), flight conditions for 0.5~0.9 and 0.945 Ma, attack angle α between -5 ° ~ +5 °. In the CFD simulation results show that under the same conditions (Mach number and angle of attack), as the warhead fuze increases 4 slices of duck rudder, the force area increases, so the drag coefficient and the lift coefficient are increased, in which Model B (Slope_Canard) is the largest. The trajectory calculation is also used to carry out the trajectories at the 0.945M and 800 degree, the maximum range of Original is the farthest. The other maximum height to Original, model A (similar, the difference is only 1 meters) are the highest, mainly because the program is the main control parameters of resistance, but with a smaller resistance, in the bullet weight difference, can obtain a far range. The impact of maximum range between Original and model A is only 318meters (5.15%), so the 3 types of bomb can be seen in range is not far. It can continue to study the canard in different deflection and rotation conditions.Finally to find the establishment of the external Ballistic correction database, for development of two-dimensional ballistic correction fuze reference in the future. This study establishes a set of fuze configuration aerodynamic design, flow field analysis ratio and flight trajectory simulation method to provide the database for the advance design and development of ballistic correction fuze, and saves the related cost of live ammunition test. Key words: mortar, aerodynamic performance of fuze configurations, canard, computational fluid dynamics

Η σύγχρονη επιστήμη της εξωτερικής βλητικής έχει εξελιχθεί ως εξειδικευμένος κλάδος της δυναμικής των στερεών σωμάτων, που κινούνται υπό την επίδραση της βαρύτητας και των αεροδυναμικών δυνάμεων και ροπών. Στην παρούσα διατριβή μελετάται η προσομοίωση του δυναμικού μοντέλου ατμοσφαιρικής τροχιάς των 6 βαθμών ελευθερίας (6-DOF), εφαρμόζεται για ακριβή πρόβλεψη τροχιών από διάφορες γωνίες βολής σε μικρά και σε μεγάλα βεληνεκή και γίνεται σύγκριση με το γραμμικό μοντέλο τροχιάς, για περιστρεφόμενα ή μη περιστρεφόμενα βλήματα και σφαίρες λαμβάνοντας υπόψη τον αριθμό Mach και τις μεταβολές της συνολικής γωνίας εκτροπής σε σχέση με τους μεταβλητούς και σταθερούς αεροδυναμικούς συντελεστές. Επίσης, μελετώνται τα δύο είδη ευστάθειας του βλήματος: η στατική ή γυροσκοπική ευστάθεια που αφορά τη στατική θέση ισορροπίας του βλήματος και η δυναμική ευστάθεια που αφορά την κινητική του κατάσταση. Η λύση της διαφορικής εξίσωσης για ολοκληρωμένη ή απλοποιημένη κίνηση περιστρεφόμενων αξονοσυμμετρικών βλημάτων, μπορεί να μας περιγράψει την ακρογωνιαία φύση της επικυκλικής κίνησης των βλημάτων. Τέλος, αναπτύσσεται νέα σχέση υπολογισμού της επίδρασης του φαινόμενου της αεροδυναμικής αναπήδησης της ταχύτητας για περιστρεφόμενα βλήματα τα οποία πυροδοτούνται οριζόντια από μεταβλητές γωνίες, μέσα από ιπτάμενο όχημα (ελικόπτερο, πολεμικό αεροπλάνο).
On the battlefield, it is well known that the target effects using artillery systems diminish exponentially with the number of rounds fired at a particular target. To maximize target effects, rounds must be designed to hit a target with a minimum number of rounds that impact the target in rapid succession. The modern science of the exterior ballistics has evolved as a specialized branch of the dynamics of rigid bodies, moving under the influence of gravitational and aerodynamic forces and moments. The six degrees of freedom (6-DOF) simulation flight dynamics model is applied for the accurate prediction of short and long-range trajectories of high and low fin spin-stabilized projectiles and small bullets. Variable coefficients of aerodynamic forces, moments and Magnus effects are taken into account depending on Mach number and total angle of attack variations. The above analysis is compared to the modified linear modified simulation model for rapid trajectory predictions and high accuracy impact point computations for constant and variable aerodynamic coefficients is also applied for the accurate prediction of short and long range trajectories. The computational results of the proposed synthesized analysis give satisfactory agreement with other technical data and recognized exterior atmospheric projectile flight investigations. The variable modified atmospheric flight model can be further coupled to a suitable trajectory tracking control system for current and future control actions applied to projectiles for minimizing the estimated error to target impact area. Epicyclic motion and gyroscopic stability analysis are also examined for spinning and non-spinning projectiles. A new engineering correlation is proposed for the flat-fire disturbance due to aerodynamic jump performance firing at different angles which relative to the helicopter’s flight path motion. The computational results of the generalized aerodynamic jump formula are verified compared to McCoy’s recognized simulation modelling.

The present dissertation develops an invariant framework for 3D gesture comparison studies. 3D gesture comparison without Lagrangian models is challenging not only because of the lack of prediction provided by physics, but also because of a dual geometry representation, spatial dimensionality and non-linearity associated to 3D-kinematics. In 3D spaces, it is difficult to compare curves without an alignment operator since it is likely that discrete curves are not synchronized and do not share a common point in space. One has to assume that each and every single trajectory in the space is unique. The common answer is to assert the similitude between two or more trajectories as estimating an average distance error from the aligned curves, provided that the alignment operator is found. In order to avoid the alignment problem, the method uses differential geometry for position and orientation curves. Differential geometry not only reduces the spatial dimensionality but also achieves view invariance. However, the nonlinear signatures may be unbounded or singular. Yet, it is shown that pattern recognition between intrinsic signatures using correlations is robust for position and orientation alike. A new mapping for orientation sequences is introduced in order to treat quaternion and Euclidean intrinsic signatures alike. The new mapping projects a 4D-hyper-sphere for orientations onto a 3D-Euclidean volume. The projection uses the quaternion invariant distance to map rotation sequences into 3D-Euclidean curves. However, quaternion spaces are sectional discrete spaces. The significance is that continuous rotation functions can be only approximated for small angles. Rotation sequences with large angle variations can only be interpolated in discrete sections. The current dissertation introduces two multi-scale approaches that improve numerical stability and bound the signal energy content of the intrinsic signatures. The first is a multilevel least squares curve fitting method similar to Haar wavelet. The second is a geodesic distance anisotropic kernel filter. The methodology testing is carried out on 3D-gestures for obstetrics training. The study quantitatively assess the process of skill acquisition and transfer of manipulating obstetric forceps gestures. The results show that the multi-scale correlations with intrinsic signatures track and evaluate gesture differences between experts and trainees.