Approved for public release, distribution is unlimited / The objective of this thesis is to provide an aircraft with an optimal route to its destination that avoids encroaching into surface-to-air weapons killing envelopes in real time. The optimal route computed will be updated dynamically, depending on the location of the vehicle and the location of the Surface to Air Missile (SAM) sites. The problem was solved using heuristic algorithms instead of the conventional Dijkstra's & Bellman Ford algorithms, which are computationally expensive. Data fusion techniques such as spatial correlation and triangulation algorithms are presented in detail. Such techniques are important for situational awareness in a real time combat environment. Important information provided by onboard sensors are merged with the preplanned data to provide the operator with a better integrated picture of the combat environment. / Civilian, Singapore Ministry of Defense

Modern-day terrorist attacks present a considerable danger for commercial aircrafts. This thesis analyzes potential methods of such attacks with a critical analysis of the most dangerous type: an attack from the outside of the aircraft via a fragmentation missile warhead. Such missiles cause damage to the airframe of the aircraft through fragments created by the explosion. In this thesis, analytical geometry is used to determine the area of the aircraft affected by the fragmentation. The aircraft’s geometry and the fragments’ dispersion are calculated by analytical functions, and the effect of the damage is analyzed. A shooting experiment was also carried out, in which fragments were shot at a reinforced skin panel that was manufactured according to the real design of commercial aircraft. The results of the experiment revealed that only directly hit sections of the structure are damaged. Data obtained by the experiment was then used for the creation and improvement of the model used in the simulation by means of the finite element method. This model is used for the numerical calculation of the damage sustained. Further included in the thesis is an analysis of the change in the load-bearing capacity after such an attack. The relationship between the size of the damage and its effect on the load-bearing capacity of the component as well as the entire structure is defined. First, the effect of component damage is analyzed via the FMEA/FMECA methods. This analysis is then extended using fuzzy logic. Fuzzy logic analysis is based on the determination of the size of the damaged component area and the component’s importance on the structure’s carry loads. Application of the defined approach is described for several parts of an aircraft’s life cycle, including development, operation after the terrorist attack, and assessment of causes after a crash caused by a fragmentation missile warhead.

Approved for public release, distribution is unlimited / The United States Navy requires radical and innovative ways to model and design multifunction phased array radars. This thesis puts forth the concept that Genetic Algorithms, computer simulations that mirror the natural selection process to develop creative solutions to complex problems, would be extremely well suited in this application. The capability of a Genetic Algorithm to predict adequately the behavior of an array antenna with randomly located elements was verified with expected results through the design, construction, development and evaluation of a test-bed array. The test-bed array was constructed of commercially available components, including a unique and innovative application of a quadrature modulator microchip used in commercial communications applications. Corroboration of predicted beam patterns from both Genetic Algorithm and Method of Moments calculations was achieved in anechoic chamber measurements conducted with the test-bed array. Both H-plane and E-plane data runs were made with several phase steered beams. In all cases the measured data agreed with that predicted from both modeling programs. Although time limited experiments to beam forming and steering with phase shifting, the test-bed array is fully capable of beam forming and steering though both phase shifting and amplitude tapering. / Outstanding Thesis / Lieutenant Commander, United States Navy

My doctoral project investigates the impact of Ronald Reagan’s Strategic Defense Initiative on transatlantic relations during the period 1983-86. The dissertation focuses on the three main European powers, namely Britain, France, and the Federal Republic of Germany, and examines their reaction to SDI both individually and comparatively. The study exploits SDI’s position at the intersection of nuclear strategy, political ideology, Cold War diplomacy, and industrial politics to offer a multifaceted, multi-national, and primary source-based analysis of US-European relations during the Reagan Presidency. The picture of the transatlantic relationship which emerges from the dissertation is a complex and nuanced one. On the one hand, the analysis argues that relations across the Atlantic during the Reagan era cannot be reduced to a scenario of accelerating ‘drift’ between the United States and Western Europe. Instead, on SDI as well as on other matters, moments of acute friction alternated with a constantly renewed search for dialogue, cooperation, and compromise on the part of the Europeans and also, if to a lesser degree, of the Americans. On the other hand, the ‘exceptionalist’ ideology and worldview underpinning SDI, the prevailing indifference in Washington to its implications for NATO, and most importantly the persistent anti-nuclear rhetoric and ambitions associated with the initiative revealed a distinct lack of sensitivity to European interest by the Reagan administration. As the dissertation shows, the anti-nuclear drive inherent in SDI, which both reflected and reinforced Reagan’s deep-seated interest in nuclear abolition, constituted the most disruptive aspect of the initiative from the viewpoint of European leaders. In these respects, the SDI controversy epitomises the unilateral tendencies and increasingly divergent priorities from those of the European allies which characterised much of the Reagan administration’s foreign policy – making the 1980s a decade of recurrent tensions in transatlantic relations.

The global Cold War is used frequently by historians to frame the context of political, economic, social, military, and geographic history of the 20th century. This is often the case in Africa as well. This thesis set out to explore U.S.- South African relations during the 1960s. After conducting research in Record Group 59 (State Department Records) of the National Archives from 1967-1973, three case studies emerged that suggested that reexamination of how historians traditionally view U.S.-South African relations during this time period is necessary. The three case studies include U.S. use of naval ports in South Africa, the strategic geographic location of South Africa and its importance to NASA's satellite and missile tracking stations, and the policy of selling of weapons to South Africa by the U.S. While this is by no means an exhaustive study of this time period due to limited time in the National Archives, it does offer promise for more research involving this topic.

No description available.

This thesis deals with development of guidance laws for advanced applications. Two class of guidance problems, namely, impact angle constrained guidance and pulsed guidance for exo-atmospheric engagements, are considered here. Three impact angle constrained guidance schemes are developed using (i) Proportional navigation guidance (PNG), (ii) State Dependent Riccati Equation (SDRE) technique and (iii) geometric concepts, respectively. A collision course based pulsed guidance law is presented for exo-atmospheric interceptors. Proportional Navigation Guidance (PNG) law is the most widely used guidance law because of its ease of implementation and efficiency. However, in its original form, it achieves only a limited set of impact angles. A two stage PNG law is presented for achieving all impact angles against a stationary target. In the first phase of guidance, an orientation PNG command is used. The orientation navigation constant (N ) is a function of the initial engagement geometry and has a lower value (N less than 2). It is proved that following the orientation trajectory, the interceptor can switch to N = 2 and achieve the desired impact angle. Simulations, with a constant speed and with a realistic interceptor model, show successful interception of the target with all desired impact angles. Feedback implementation of the guidance law results in negligible errors in impact angle with uncompensated autopilot delays. The idea of a two-stage PNG law with impact angle constraint is further used to develop a guidance law for intercepting moving targets. Following the orientation trajectory, the interceptor can switch to N = 3 and achieve the desired impact angle. It is proved that the guidance achieves all impact angles in a surface-to-surface engagement scenario with receding and approaching targets, respectively. In a air-to-surface engagement scenario, it is proved that the guidance law achieves all impact angles in a deterministic set. Constant speed and realistic interceptor models are used for simulations. Results show negligible error in impact angle and miss distance for moving targets. The guidance law, in its feedback implementation form, achieves the desired impact angle for interceptors with delay and with a maneuvering target. The impact angle errors are low with negligible errors in miss distance. Next, the impact angle constrained guidance problem against a stationary target is solved as a non-linear regulator problem using the SDRE technique. The interceptor guidance problems are of finite time nature. As the main contribution of this part of the work, we solve a finite time interceptor guidance problem with infinite horizon SDRE formulation by choosing the state weighting matrix as a function of time-to-go. Numerical simulations are carried out both for a constant speed interceptor model and a realistic interceptor model. Simulations for both the models are carried out for various impact angles and firing angles. Robustness of the proposed guidance law with respect to autopilot lag is also verified by simulations. Results obtained show the efficiency of the SDRE approach for impact angle constrained missile guidance. A geometric guidance scheme is proposed for lateral interception of targets in a planar engagement scenario in the absence of line-of-sight rate information. A kill-band is defined for target initial positions capturable by an arc maneuver, followed by a straight line path by the interceptor. Guidance law for capturing targets inside the kill-band is presented and is further modified for targets outside the kill-band. Based on analytical studies on the kill-band, a guidance law is proposed for lateral interception of maneuvering targets. Simulations are carried with for typical low speed engagements. The concept of kill-band provides an inherent robustness to the proposed guidance law with respect to uncompensated system delays and target maneuver. As the final part of the work, an interceptor endgame pulsed guidance law for exoatmospheric engagements is derived by using the notion of collision heading. The proposed guidance law is derived in steps by (i) Obtaining the collision heading based on the collision triangle engagement geometry and then (ii) Computing the width of the pulse fired by the divert thruster to attain the collision heading. It is shown that this strategy is more effective than the existing zero effort miss (ZEM) based guidance laws for intercepting targets with higher heading angles off the nominal head-on collision course. A result on pulse firing sequence is also presented showing that firing pulses in quick succession results in minimum pulse widths and hence minimum control effort for a desired miss distance. Simulations are carried out for various engagement scenarios. Results show better miss-distance and divert thrust performance as compared to the existing ZEM based law.

The recent interests in the necessity of high maneuverability and vertical launching triggered namely the unconventional control design techniques that are effective at high angle of attack flight regimes. For most of missile configurations, this interest required thrust vector control together with conventional aerodynamic control. In this study, nonlinear modeling and dynamical analysis of a surface to air missile with both aerodynamic and thrust vector control is investigated. Aerodynamic force and moment modeling of the presented missile includes the challenging high angle of attack aerodynamics behavior and the so called hybrid control, which utilizes both tail fins and jet vanes as control surfaces. Thrust vector and aerodynamic control effectiveness is examined during flight envelope. Different autopilot designs are accomplished with hybrid control. Midcourse and terminal guidance algorithms are implemented and performed on target sets including maneuverable targets. A different initial turnover strategy is suggested and compared with standard skid-to-turn maneuver. Comparisons of initial roll with aerodynamic and thrust vector control are examined. Afterwards, some critical maneuvers and hybrid control ratio is studied with a real coded genetic algorithm. Rapid turnover for low altitude targets, intercept maneuver analysis with hybrid control ratio and lastly, engagement initiation maneuver optimization is fulfilled.

Hypersonic vehicles are exposed to severe heating loads during their flight in the atmosphere. In order to minimize the heating problem, a variety of cooling techniques are presently available for hypersonic blunt bodies. Introduction of a forward-facing cavity in the nose tip of a blunt body configuration of hypersonic vehicle is one of the most simple and attractive methods of reducing the convective heating rates on such a vehicle. In addition to aerodynamic heating, the overall drag force experienced by vehicles flying at hypersonic speeds is predominate due to formation of strong shock waves in the flow. Hence, the effective management of heat transfer rate and aerodynamic drag is a primary element to the success of any hypersonic vehicle design. So, precise information on both aerodynamic forces and heat transfer rates are essential in deciding the performance of the vehicle. In order to address the issue of both forces and heat transfer rates, right kind of measurement techniques must be incorporated in the ground-based testing facilities for such type of body configurations. Impulse facilities are the only devices that can simulate high altitude flight conditions. Uncertainties in test flow conditions of impulse facilities are some of the critical issues that essentially affect the final experimental results. Hence, more reliable and carefully designed experimental techniques/methodologies are needed in impulse facilities for generating experimental data, especially at hypersonic Mach numbers. In view of the above, an experimental program has been initiated to develop novel techniques of measuring both the aerodynamic forces and surface heat transfer rates. In the present investigation, both aerodynamic forces and surface heat transfer rates are measured over the test models at hypersonic Mach numbers in IISc hypersonic shock tunnel HST-2, having an effective test time of 800 s. The aerodynamic coefficients are measured with a miniature type accelerometer based balance system where as platinum thin film sensors are used to measure the convective heat transfer rates over the surface of the test model. An internally mountable accelerometer based balance system (three and six-component) is used for the measurement of aerodynamic forces and moment coefficients acting on the different test models (i.e., blunt cone with after body, blunt cone with after body and frustum, blunt cone with after body-frustum-triangular fins and sharp cone with after body-frustum-triangular fins), flying at free stream Mach numbers of 5.75 and 8 in hypersonic shock tunnel. The main principle of this design is that the model along with the internally mounted accelerometer balance system are supported by rubber bushes and there-by ensuring unrestrained free floating conditions of the model in the test section during the flow duration. In order to get a better performance from the accelerometer balance system, the location of accelerometers plays a vital role during the initial design of the balance. Hence, axi-symmetric finite element modeling (FEM) of the integrated model-balance system for the missile shaped model has been carried out at 0° angle of attack in a flow Mach number of 8. The drag force of a model was determined using commercial package of MSC/NASTRAN and MSC/PATRAN. For test flow duration of 800 s, the neoprene type rubber with Young’s modulus of 3 MPa and material combinations (aluminum and stainless steel material used as the model and balance) were chosen. The simulated drag acceleration (finite element) from the drag accelerometer is compared with recorded acceleration-time history from the accelerometer during the shock tunnel testing. The agreement between the acceleration-time history from finite-element simulation and measured response from the accelerometer is very good within the test flow domain. In order to verify the performance of the balance, tests were carried out on similar standard AGARD model configurations (blunt cone with cylinder and blunt cone with cylinder-frustum) and the results indicated that the measured values match very well with the AGARD model data and theoretically estimated values. Modified Newtonian theory is used to calculate the aerodynamic force coefficient analytically for various angles of attack. Convective surface heat transfer rate measurements are carried out by using vacuum sputtered platinum thin film sensors deposited on ceramic substrate (Macor) inserts which in turn are embedded on the metallic missile shaped body. Investigations are carried out on a model with and without fin configurations in HST-2 at flow Mach number of 5.75 and 8 with a stagnation enthalpy of 2 MJ/kg for zero degree angle of attack. The measured heating rates for the missile shaped body (i.e., with fin configuration) are lower than the predicted stagnation heating rates (Fay-Riddell expression) and the maximum difference is about 8%. These differences may be due to the theoretical values of velocity gradient used in the empirical relation. The experimentally measured values are expressed in terms of normalized heat transfer rates, Stanton numbers and correlated Stanton numbers, compared with the numerically estimated results. From the results, it is inferred that the location of maximum heating occurs at stagnation point which corresponds to zero velocity gradient. The heat-transfer ratio (q1/Qo)remains same in the stagnation zone of the model when the Mach number is increased from 5.75 to 8. At the corners of the blunt cone, the heat transfer rate doesn’t increase (or) fluctuate and the effects are negligible at two different Mach numbers (5.75 and 8). On the basis of equivalent total enthalpy, the heat-transfer rate with fin configuration (i.e., at junction of cylinder and fins) is slightly higher than that of the missile model without fin. Attempts have also been made to evaluate the feasibility of using forward facing cavity as probable technique to reduce the heat transfer rate and to study its effect on aerodynamic coefficients on a 41° apex angle missile shaped body, in hypersonic shock tunnel at a free stream Mach number of 8. The forward-facing circular cavities with two different diameters of 6 and 12 mm are chosen for the present investigations. Experiments are carried out at zero degree angle of attack for heat transfer measurements. About 10-25 % reduction in heat transfer rates is observed with cavity at gauge locations close to stagnation region, whereas the reduction in surface heat transfer rate is between 10-15 % for all other gauge locations (which is slightly downstream of the cavity) compared with the model without cavity. In order to understand the influence of forward facing cavities on force coefficients, measurement of aerodynamic forces and moment coefficients are also carried out on a missile shaped body at angles of attack. The same six component balance is also being used for subsequent investigation of force measurement on a missile shaped body with forward facing cavity. Overall drag reductions of up to 5 % is obtained for a cavity of 6 mm diameter, where as, for the 12 mm cavity an increase in aerodynamic drag is observed (up to about 10%). The addition of cavity resulted in a slight increase in the missile L/D ratio and did not significantly affect the missile lateral components. In summary, the designed balances are found to be suitable for force measurements on different test models in flows of duration less than a millisecond. In order to compliment the experimental results, axi-symmetric, Navier-Stokes CFD computations for the above-defined models are carried out for various angles of attack using a commercial package CFX-Ansys 5.7. The experimental free stream conditions obtained from the shock tunnel are used for the boundary conditions in the CFD simulation. The fundamental aerodynamic coefficients and heat transfer rates of experimental results are shown to be in good agreement with the predicted CFD. In order to have a feeling of the shock structure over test models, flow visualization experiments have been carried out by using the Schlieren technique at flow Mach numbers of 5.75 and 8. The visualized shock wave pattern around the test model consists of a strong bow shock which is spherical in shape and symmetrical over the forebody of the cone. Experimentally measured shock stand-off distance compare well with the computed value as well as the theoretically estimated value using Van Dyke’s theory. These flow visualization experiments have given a factual proof to the quality of flow in the tunnel test section.

North Korea twice conducted ballistic missile tests close to Japan in 1998 and 2006. While Japan responded with non-coercive condemnations to demonstrate its disapproval in 1998, it imposed unilateral economic sanctions in 2006, marking the first instance in post-World War II of applying a substantial coercion to punish a neighbouring state. The research asks why Japanese policy toward the North shifted for a seemingly identical type of provocation. The dissertation seeks contextual explanations by using inductive process-tracing, a type of ‘middle approach’ between historical narratives and parsimonious theories. It is applied to highlight the underlying mechanism through which public discursive changes concerning national security and North Korea during this eight-year period influenced the subsequent policy shift in 2006. The dissertation concludes that the unilateral sanctions were not necessarily a calculated strategic response to punish the missile launch (or North Korean nuclear programs) per se, but were a direct consequence of a deeper shift in societal discourse taking place beforehand. During the eight-year period, there had been other visible provocations and shocks originating from the North, especially the sensational revelation in 2002 of past North Korean abductions of Japanese citizens. These highly-publicized incidents facilitated the Japanese public to be increasingly conscious about Japan’s security weaknesses and re-evaluate its historical relations with its neighbour, leading to a hardened domestic environment in which the new idea of pressuring the North became a feasible option even before 2006. These North Korean provocations and the resulting societal security discourse, along with concurrent structural changes in the Japanese government and mass media which made them both highly susceptible to discursive currents among citizens, mutually interacted to produce the policy result when the opportunity arose. The research, however, also challenges the popular view that the sanctions are the first example of the wholesale transformation of Japan’s post-war ‘pacifist’ security principles. It argues that the confined means (economic) by which the sanctions were imposed reflects the highly nuanced discourse, which endorses Japan’s legitimate right to specifically punish the North for the harms done, but that the societal momentum is not equally supportive of the more controversial areas concerning military usage and the current constitution.