This dissertation offers a novel quantitative method for assessing an actor's subjective temporal orientation. Our method involves the use of supervised machine learning techniques in concert with natural language processing tools and linguistic principles. We suggest our method may offer a clandestine technique for extracting aspects of an actor’s temporal orientations from right behind their back. This capacity occurs because of the unique ways time references are reflected in language syntax. This reflection does not simply occur in face-to-face spoken interactions, but also resides in recorded vocal transcripts and within textual documents articulated by speakers for a social audience (e.g., political speeches). . From a social theory point of view, we argue that our technique can help objectify some of the major links theorists have long made between the temporal features of mind, subjective meaning, and social processes. Temporal orientation has long been defined as a tripartite mental process. Edmund Husserl famously defined this process as involving retention (a mental focus on past), presentation (a mental focus on the present) or protention (a mental envisioning of the future). From a pure phenomenology perspective, Husserl’s innovation was to link this mental interlocking process with meaning-making. For Husserl, it was directly through an actor’s temporal orientation that meaning became variably constituted and the problem of subjectivity emerged. From a sociological point of view, it is primarily through Alfred Schutz’s formulation of social phenomenology that Husserl’s tripartite system was opened to accommodate the influence of the social in meaning-making. This opening has possessed a long-standing contradiction. For Schutz, endogenous social structure could affect where an actor temporally orients. The resulting implication is that social structure could have a direct effect on how actors assign specific meanings in social systems. Even more, social structure could facilitate shared temporal orientations among actors. However, Schutz also promoted the idea that different temporal orientations could explain how different meanings could be assigned to the same social object by disparate actors. This possibility served as the centerpiece of Schutz’s well-known methodological critique of Max Weber’s direct linkage between subjective meaning, motive, and empathetic based interpretations of social action. To carry out our efforts to quantify how the subjective processes of temporal orientation appear to be influenced by endogenous social processes, we employed our algorithm on three different text-based data sets. We suggest these datasets possess strong reflections of the social world. The first dataset entails a collection of matched twitter tweets that correspond to Trump’s reelection bid and Biden’s challenge during the 2020 period. In this dataset, our method illustrates how both candidates appear to have different temporal orientations despite being bounded by a similar social event. We suggest this finding may reflect the relationship between what Schütz called inner duration and the influence of external stocks of knowledge (i.e., external structures.) The second dataset corresponds to a recorded conversational transcript of the Cuban missile crisis, taken from President Kennedy’s Executive Committee of the National Security Council (ExComm) on the 6th of October in 1962. Using our algorithm, we offer objective measures of homogenous temporal orientations of committee members that are consistent with meso-group conformity. We suggest that our method may offer a novel way of measuring group conformity in general. The third dataset consists of the State of the Union Corpora (SOU). In this dataset, we apply our algorithm to identify changes in temporal orientation occurring among a single President’s entire collection of SOU speeches. Furthermore, we compare the average temporal orientation of the Presidents in relation to various social categories, such as party affiliation and societal events. The scope of the Presidents inventoried for temporal orientation is restricted from Eisenhower to Biden.

<p dir="ltr">In the pursuit of establishing a sustainable space economy within the cislunar region, it is vital to formulate transfer design strategies that uncover economically viable highways between different regions of the space domain. The inherent complexity of spacecraft dynamics in the cislunar space poses challenges in determining feasible transfer options. However, the motion characterized by known dynamical structures modeled through the circular restricted three-body problem (CR3BP) aids in the identification of pathways with reasonable maneuver costs and flight times. A framework is proposed that incorporates a quasi-periodic orbit (QPOs) as an option to design transfer scenarios. This investigation focuses on the construction of transfers between periodic orbits. The framework is exemplified by the construction of pathways between an L2 9:2 synodic resonant Near-Rectilinear Halo Orbit (NRHO) and a planar Moon-centered Distant Retrograde Orbit (DRO). The innate difference in the geometries of the departure and arrival orbits of the sample case, along with the lack of natural flows towards and away from them, imply that links between these orbits may necessitate costly maneuvers. A strategy is formulated that leverages the stable and unstable manifolds associated with intermediate periodic orbits and quasi-periodic orbits to construct end-toend trajectories. As part of this strategy, a systematic methodology is outlined to streamline the determination of transfer options provided by the 5-dimensional manifolds associated with a QPO family. This approach reveals multiple local basins of solutions, both interior and exterior-types, characterized by selected intermediate orbits. The construction of transfers informed by the manifolds associated with QPOs is more intricate than those based on periodic orbits. However, QPO-derived solutions allow for the recognition of alternative local basins of solutions and often offer more cost-effective transfer options when compared to trajectories designed using periodic orbits that underlie the QPOs.</p>

<p>  </p> <p>  </p> <p>An approach to modify surface flashover of insulators in vacuum by limiting duration of its high-current stage responsible for the damaging effects of a classic flashover was developed. The flashover assembly was made by TorrSeal-gluing copper electrodes (10 x 10 x 0.5 mm) to both side of an alumina ceramic sheet (0.635 mm thick). The modified flashover, referred to as low energy surface flashover (LESF), was achieved by utilization of a high voltage (HV) nanosecond pulser or addition of a resistor in series with the LESF assembly when HV DC was utilized. The duration of LESF was visualized by ICCD fast photography to be 100 – 200 ns accompanying electrical characteristics measurements, which gave insight of a way to control the flashover duration by inserting additional capacitor in parallel with the LESF assembly to increase the stored energy prior to breakdown. The LESF assembly was tested for > 1.5 million consecutive pulses and remained operational, while operation in high energy regime with parallel capacitor (4nF) lead to significant damage after 200 pulses.</p> <p>The igniting capabilities of LESF assembly was demonstrated via successful triggering of vacuum arc and a prototype pulsed plasma accelerator. The plasma plume propagation speed and angular distribution was measured via Langmuir probes. Efforts were made for temporally resolved spectroscopy measurements. </p> <p>The LESF assembly was improved by replacing TorrSeal-gluing with direct bonding of copper to alumina ceramic and changing the configuration from parallel plate to coaxial. The improved assembly was demonstrated to be operational throughout and after an extended test of 10 million pulses. A higher resolution ICCD photography revealed finer LESF discharge features including initial bright line across the insulator developing into a double-jet plasma plume propagating at around 10⁵m/s and later-on point-like attachment of the discharge column to the electrodes. The composition of the plasma and erosion pattern on the LESF assembly was studied via SEM/EDX analysis, which supported the predominant ceramic erosion over copper electrodes erosion.</p>

<p dir="ltr">Improving launch vehicle and satellite propulsion system performance directly correlates to the delivery of more mass (or quantity) on orbit from launch vehicles, longer duration satellite missions, and longer ranges for missiles/interceptors. Alternative propulsion devices such as rotating detonation engines (RDEs) offer the potential for significant performance gains but their operability has only been demonstrated on “battle hardened” laboratory devices for rocket applications. The objective of this research was to demonstrate cooling and structural approaches that mature rotating detonation rocket engines (RDREs) to flight like maturation levels.</p><p dir="ltr">Multiple 1.6”/4.1 cm diameter RDE combustors were designed, fabricated, and tested. The RDE tested the most accumulated 309 seconds of hot fire testing and 118 starts/shutdowns. Long duration testing was completed to characterize heat flux and high cycle fatigue (HCF) loading. Large quantities of short duration tests were completed to evaluate thermal cycling impacts to the combustor structure and evaluate low cycle fatigue (LCF) loading. The hardware experienced 118 LCF loadings on the combustor cooling passages, equivalent to the amount of thermal cycle starts and shutdowns. An endurance test was completed at 60 seconds in duration, demonstrating operation well beyond thermal steady state. Additionally, ~3.7 million HCF loadings were placed on the combustor cooling passages, equivalent to the approximate amount of detonation wave passes present for all of the WC 2.0 testing.</p><p dir="ltr">Predicted operating pressures ranged from 5 to 15 atm. The highest-pressure conditions resulted in hot gas wall temperatures exceeding 1000°F on the outerbody of the combustor and injector face temperatures peaking at 350°F. Water calorimetry was used to compute heat fluxes, which were then compared to traditional rocket engine throat level heat fluxes calculated using Bartz equations under average operating conditions. The outerbody heat fluxes reached up to 3.7 kW/cm², while injector face heat fluxes reached a maximum of 1.6 kW/cm². When compared to Bartz throat level values, the outer-body heat fluxes varied from 0.9 to 1.6 times the throat level values, and injector heat fluxes ranged from 0.3 to 0.5 times the throat level values.</p><p dir="ltr">A combined thermal and pressure loading fatigue assessment was completed that took into consideration mean stresses and cumulative damage from the spectrum of loading events. Traditional rocket combustor life is typically limited by the thermal cycles that can be placed on the cooling channel hot wall. The fatigue analysis results highlight the reduction in available low cycle fatigue life as RDE's experience larger thermal loads when compared to traditional rocket combustors. Low cycle fatigue life will become especially challenging in higher chamber pressure combustors where thermal environments are more extreme, and the ability keep hot wall temperatures within acceptable levels is more challenging.</p><p dir="ltr">The study also highlights that the passing detonation wave provides a high cycle fatigue (HCF) failure mechanism that is not present in traditional rocket combustors. This failure mechanism is the result of the pressure pulse provided by the passing detonation wave causing a variable load on the hot wall. This variable load is applied at frequencies commonly in the 10's of kHz, resulting in large quantities of loading cycles when operated at rocket like durations (>60 sec). This HCF failure mechanism is most impactful at larger chamber pressures where the detonation pressure ratio causes peak pressures to be elevated, resulting in larger cyclic stresses and strains in the hot wall. The results indicate that high chamber pressure combustors may experience HCF life exceedances within seconds of operation.</p>

La thèse porte sur le développement des techniques non linéaires robustes de stabilisation et commande des systèmes avec perturbations de model. D’abord, on introduit les concepts de base de stabilité et stabilisabilité robuste dans le contexte des systèmes non linéaires. Ensuite, on présente une méthodologie de stabilisation par retour d’état en présence d’incertitudes qui ne sont pas dans l’image de la commande («unmatched»). L’approche récursive du «backstepping» permet de compenser les perturbations «unmatched» et de construire une fonction de Lyapunov contrôlée robuste, utilisable pour le calcul ultérieur d’un compensateur des incertitudes dans l’image de la commande («matched»). Le contrôleur obtenu est appelé «recursive Lyapunov redesign». Ensuite, on introduit la technique de stabilisation par «Immersion & Invariance» comme outil pour rendre un donné contrôleur non linéaire, robuste par rapport à dynamiques non modelées. La première technique de contrôle non linéaire robuste proposée est appliquée au projet d’un autopilote pour un missile air-air et au développement d’une loi de commande d’attitude pour un satellite avec appendices flexibles. L’efficacité du «recursive Lyapunov redesign» est mis en évidence dans le deux cas d’étude considérés. En parallèle, on propose une méthode systématique de calcul des termes incertains basée sur un modèle déterministe d’incertitude. La partie finale du travail de thèse est relative à la stabilisation des systèmes sous échantillonnage. En particulier, on reformule, dans le contexte digital, la technique d’Immersion et Invariance. En premier lieu, on propose des solutions constructives en temps continu dans le cas d’une classe spéciale des systèmes en forme triangulaire «feedback form», au moyen de «backstepping» et d’arguments de domination non linéaire. L’implantation numérique est basée sur une loi multi-échelles, dont l’existence est garantie pour la classe des systèmes considérée. Le contrôleur digital assure la propriété d’attractivité et des trajectoires bornées. La loi de commande, calculée par approximation finie d’un développement asymptotique, est validée en simulation de deux exemples académiques et deux systèmes physiques, le pendule inversé sur un chariot et le satellite rigide. / The dissertation deals with the problems of stabilization and control of nonlinear systems with deterministic model uncertainties. First, in the context of uncertain systems analysis, we introduce and explain the basic concepts of robust stability and stabilizability. Then, we propose a method of stabilization via state-feedback in presence of unmatched uncertainties in the dynamics. The recursive backstepping approach allows to compensate the uncertain terms acting outside the control span and to construct a robust control Lyapunov function, which is exploited in the subsequent design of a compensator for the matched uncertainties. The obtained controller is called recursive Lyapunov redesign. Next, we introduce the stabilization technique through Immersion \& Invariance (I\&I) as a tool to improve the robustness of a given nonlinear controller with respect to unmodeled dynamics. The recursive Lyapunov redesign is then applied to the attitude stabilization of a spacecraft with flexible appendages and to the autopilot design of an asymmetric air-to-air missile. Contextually, we develop a systematic method to rapidly evaluate the aerodynamic perturbation terms exploiting the deterministic model of the uncertainty. The effectiveness of the proposed controller is highlighted through several simulations in the second case-study considered. In the final part of the work, the technique of I\& I is reformulated in the digital setting in the case of a special class of systems in feedback form, for which constructive continuous-time solutions exist, by means of backstepping and nonlinear domination arguments. The sampled-data implementation is based on a multi-rate control solution, whose existence is guaranteed for the class of systems considered. The digital controller guarantees, under sampling, the properties of manifold attractivity and trajectory boundedness. The control law, computed by finite approximation of a series expansion, is finally validated through numerical simulations in two academic examples and in two case-studies, namely the cart-pendulum system and the rigid spacecraft.

<p>Att utveckla en publik webbtjänst kan tyckas lätt, men att få denna till en framgångsrik och lönsam applikation är en annan sak. Konkurrensen är idag stenhård och en bra applikation är långt ifrån det enda man behöver för att lyckas.</p><p>Studiens syfte var att kartlägga och öka förståelsen kring publik webbtjänstutveckling, ett område som tidigare inte fått så stor uppmärksamhet i den akademiska världen. Studien bygger på ett empiriskt material insamlat genom intervjuer med några av Sveriges främsta IT-entreprenörer inom området. Studien inkluderade även ett praktiskt moment där utveckling av inbjudningssajten InviClub.se genomförts för att praktiskt testa teorierna.</p><p>Vår studie visade på att traditionella systemutvecklingsmetoder är svåra att tillämpa på detta område. En faktor som visade sig vara av yttersta vikt för lyckade projekt var snabbhet, något som de traditionella modellerna RUP och Vattenfallsmodellen inte prioriterar. Därför tog utvecklandet av MISSILE (Marknadsföring, Interaktion, Snabbhet, Snack, Integration, Lock-In samt Enkelhet) vid. Denna modell är en lättviktsmodell som är baserad på både teoretisk och praktisk grund, och är speciellt anpassad för webbutveckling inom publika webbtjänster. Modellen tar vara på och behandlar de nyckelfaktorer som kommit fram under studiens gång, genom att utkast till en tidigare egenutvecklad teoretisk modell, MALIN (Marknadsföring, Användbarhet, Lock-In) jämfördes med vad experter inom området publika webbtjänster tyckte var framgångsfaktorer för att utveckla publika webbtjänster.</p><p>Vi anser att uppsatsen har stort värde då det inte finns tidigare forskning inom området publika webbtjänster. Vi anser även att det finns ett stort praktiskt värde av MISSILE-modellen, då modellen kan vägleda IT-entreprenörer att utveckla nya publika webbtjänstprojekt mer framgångsrikt och snabbare än tidigare.</p>

Att utveckla en publik webbtjänst kan tyckas lätt, men att få denna till en framgångsrik och lönsam applikation är en annan sak. Konkurrensen är idag stenhård och en bra applikation är långt ifrån det enda man behöver för att lyckas. Studiens syfte var att kartlägga och öka förståelsen kring publik webbtjänstutveckling, ett område som tidigare inte fått så stor uppmärksamhet i den akademiska världen. Studien bygger på ett empiriskt material insamlat genom intervjuer med några av Sveriges främsta IT-entreprenörer inom området. Studien inkluderade även ett praktiskt moment där utveckling av inbjudningssajten InviClub.se genomförts för att praktiskt testa teorierna. Vår studie visade på att traditionella systemutvecklingsmetoder är svåra att tillämpa på detta område. En faktor som visade sig vara av yttersta vikt för lyckade projekt var snabbhet, något som de traditionella modellerna RUP och Vattenfallsmodellen inte prioriterar. Därför tog utvecklandet av MISSILE (Marknadsföring, Interaktion, Snabbhet, Snack, Integration, Lock-In samt Enkelhet) vid. Denna modell är en lättviktsmodell som är baserad på både teoretisk och praktisk grund, och är speciellt anpassad för webbutveckling inom publika webbtjänster. Modellen tar vara på och behandlar de nyckelfaktorer som kommit fram under studiens gång, genom att utkast till en tidigare egenutvecklad teoretisk modell, MALIN (Marknadsföring, Användbarhet, Lock-In) jämfördes med vad experter inom området publika webbtjänster tyckte var framgångsfaktorer för att utveckla publika webbtjänster. Vi anser att uppsatsen har stort värde då det inte finns tidigare forskning inom området publika webbtjänster. Vi anser även att det finns ett stort praktiskt värde av MISSILE-modellen, då modellen kan vägleda IT-entreprenörer att utveckla nya publika webbtjänstprojekt mer framgångsrikt och snabbare än tidigare.

Autonomous aerial vehicles like missiles and unmanned aerial vehicles (UAVs) have attracted various military and civilian applications. The primary guidance objective of any autonomous vehicle is to reach the desired destination point (target or waypoint). However, many practical engagements impose additional constraints like minimum control effort, a desired final velocity direction or a predefined engagement time. This thesis addresses engagement time constrained guidance problems pertaining to missiles and UAVs. The first part of the thesis discusses a nonlinear guidance law for impact time control of missiles against stationary target. The guidance law is designed with a particular choice of missile heading error variation as a function of ran to-target. The proposed heading error variation leads to an exact closed-form expression for the impact time. controlling the impact time, a closed-form relation is derived relating the control parameter to the desired impact time. A new Lyapunov based guidance law with a monotonically decreasing lateral acceleration is proposed in the next part of the thesis. An exact expression for impact time with minimum and maximum achievable impact times is derived. A control parameter is proposed with a closed-form relationship to the desired impact time. Using the concept of predicted interception point, the two guidance laws are extended for impact time control against non-maneuvering and moving targets. The proposed guidance models are extended to three-dimensional engagements by deducing yaw and pitch lateral accelerations satisfying the desired heading error profile. Extensive simulation studies are carried out for single missile and salvo attack scenarios. The last part of the thesis presents a guidance methodology governing the arrival time of a UAV at a waypoint. A specific arrival angle is considered as an additional constraint. The arrival constraints are satisfied by varying the navigation gain of the proportional navigation guidance law. The methodology is applied for simultaneous and sequential arrival of UAVs at a waypoint.

THE 1977 UNITED STATES ARMS EMBARGO AGAINST SOUTH AFRICA: INSTITUTION AND IMPLEMENTATION TO 1997 The institution and implementation of the 1977 mandatory United States arms embargo against South Africa and the impact thereof on relations between the United States and South Africa is investigated in this study. The investigation centers around the objectives of the United States in instituting the arms embargo, whether these objectives were met through the implementation and enforcement of the arms embargo, and whether the South African reaction to the embargo indicates the failure of the embargo to meet its objectives. The relation of the arms embargo to the foreign policy of the United States Government of the day, as well as the impact of the embargo on the South African military industry is discussed. The basis on which the problem statement is built is that close scrutiny of the implementation of the arms embargo would allow one to judge the seriousness that the United States assigned to the objectives of the arms embargo. The main objective of the embargo was to force the South African Government to abandon apartheid. Full compliance with the embargo would demonstrate the commitment of the United States to this objective, while non-compliance would be regarded by critics as a retreat from that objective. The United States’ implementation of the arms embargo would furthermore demonstrate the ability of major arms producers like the United States to reduce the threat of global violence by putting measures in place to successfully block arms and related items from being exported to potential belligerents. In conclusion to the study, it was found that the implementation of the embargo was linked to external objectives of the United States Government of the day. Thus, the strengthening or weakening of arms embargo regulations occurred according to the objectives that the Government of the day wanted to achieve. Nonetheless, the United States’ implementation of the arms embargo was generally very effective. It was also concluded that the arms embargo indeed acted as the main stimulant for the development of the world-renowned South African arms industry. This industry developed out of the determination of the white South African minority Government to remain in power, which in turn resulted in a defiant disregard for the arms embargo. Clandestine activities became the order of the day. These activities later had a major impact on the first democratically elected black government in South Africa. This government inherited a legacy of embargo violations, which led to much tension in relations with the United States in the first few years after the 1994 South African elections. The research therefore also paints a picture of the inherited struggles that the new South African Government had to face as a result of the arms embargo, and the resultant difficulties in normalizing relations with the United States. / Thesis (DPhil (History))--University of Pretoria, 2006. / Historical and Heritage Studies / unrestricted

International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, California / White Sands Missile Range (WSMR) is developing a new transportable telemetry system that consolidates various telemetry data collection functions currently being performed by separate instrumentation. The new system will provide higher data rate handling capability, reduced labor requirements, and more efficient operations support which will result in a reduction of mission support costs. Seven new systems are planned for procurement through Requirements Contracts. They will replace current mobile systems which are over 25 years old on a one-on-one basis. Regulation allows for a sixty-five percent overage on the contract and WSMR plans to make this contract available for use by other Major Range Test Facility Bases (MRTFBs). Separate line items in the contracts make it possible to vary the design to meet a specific system configuration. This paper describes both current and replacement mobile telemetry system