1,567 research outputs found

    Robust Trajectory Planning for Autonomous Parafoils under Wind Uncertainty

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    A key challenge facing modern airborne delivery systems, such as parafoils, is the ability to accurately and consistently deliver supplies into di cult, complex terrain. Robustness is a primary concern, given that environmental wind disturbances are often highly uncertain and time-varying, coupled with under-actuated dynamics and potentially narrow drop zones. This paper presents a new on-line trajectory planning algorithm that enables a large, autonomous parafoil to robustly execute collision avoidance and precision landing on mapped terrain, even with signi cant wind uncertainties. This algorithm is designed to handle arbitrary initial altitudes, approach geometries, and terrain surfaces, and is robust to wind disturbances which may be highly dynamic throughout the terminal approach. Explicit, real-time wind modeling and classi cation is used to anticipate future disturbances, while a novel uncertainty-sampling technique ensures that robustness to possible future variation is e ciently maintained. The designed cost-to-go function enables selection of partial paths which intelligently trade o between current and reachable future states. Simulation results demonstrate that the proposed algorithm reduces the worst-case impact of wind disturbances relative to state-of-the-art approaches.Charles Stark Draper Laborator

    Robust Trajectory Planning for Autonomous Parafoils under Wind Uncertainty

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    A key challenge facing modern airborne delivery systems, such as parafoils, is the ability to accurately and consistently deliver supplies into di cult, complex terrain. Robustness is a primary concern, given that environmental wind disturbances are often highly uncertain and time-varying, coupled with under-actuated dynamics and potentially narrow drop zones. This paper presents a new on-line trajectory planning algorithm that enables a large, autonomous parafoil to robustly execute collision avoidance and precision landing on mapped terrain, even with signi cant wind uncertainties. This algorithm is designed to handle arbitrary initial altitudes, approach geometries, and terrain surfaces, and is robust to wind disturbances which may be highly dynamic throughout the terminal approach. Explicit, real-time wind modeling and classi cation is used to anticipate future disturbances, while a novel uncertainty-sampling technique ensures that robustness to possible future variation is e ciently maintained. The designed cost-to-go function enables selection of partial paths which intelligently trade o between current and reachable future states. Simulation results demonstrate that the proposed algorithm reduces the worst-case impact of wind disturbances relative to state-of-the-art approaches.Charles Stark Draper Laborator

    Comparing nuclear power trajectories in Germany and the UK: from ‘regimes' to ‘democracies’ in sociotechnical transitions and Discontinuities

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    This paper focuses on arguably the single most striking contrast in contemporary major energy politics in Europe (and even the developed world as a whole): the starkly differing civil nuclear policies of Germany and the UK. Germany is seeking entirely to phase out nuclear power by 2022. Yet the UK advocates a ‘nuclear renaissance’, promoting the most ambitious new nuclear construction programme in Western Europe.Here,this paper poses a simple yet quite fundamental question: what are the particular divergent conditions most strongly implicated in the contrasting developments in these two countries. With nuclear playing such an iconic role in historical discussions over technological continuity and transformation, answering this may assist in wider understandings of sociotechnical incumbency and discontinuity in the burgeoning field of‘sustainability transitions’. To this end, an ‘abductive’ approach is taken: deploying nine potentially relevant criteria for understanding the different directions pursued in Germany and the UK. Together constituted by 30 parameters spanning literatures related to socio-technical regimes in general as well as nuclear technology in particular, the criteria are divided into those that are ‘internal’ and ‘external’ to the ‘focal regime configuration’ of nuclear power and associated ‘challenger technologies’ like renewables. It is ‘internal’ criteria that are emphasised in conventional sociotechnical regime theory, with ‘external’ criteria relatively less well explored. Asking under each criterion whether attempted discontinuation of nuclear power would be more likely in Germany or the UK, a clear picture emerges. ‘Internal’ criteria suggest attempted nuclear discontinuation should be more likely in the UK than in Germany– the reverse of what is occurring. ‘External’ criteria are more aligned with observed dynamics –especially those relating to military nuclear commitments and broader ‘qualities of democracy’. Despite many differences of framing concerning exactly what constitutes ‘democracy’, a rich political science literature on this point is unanimous in characterising Germany more positively than the UK. Although based only on a single case,a potentially important question is nonetheless raised as to whether sociotechnical regime theory might usefully give greater attention to the general importance of various aspects of democracy in constituting conditions for significant technological discontinuities and transformations. If so, the policy implications are significant. A number of important areas are identified for future research, including the roles of diverse understandings and specific aspects of democracy and the particular relevance of military nuclear commitments– whose under-discussion in civil nuclear policy literatures raises its own questions of democratic accountability

    Developing sustainability pathways for social simulation tools and services

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    The use of cloud technologies to teach agent-based modelling and simulation (ABMS) is an interesting application of a nascent technological paradigm that has received very little attention in the literature. This report fills that gap and aims to help instructors, teachers and demonstrators to understand why and how cloud services are appropriate solutions to common problems they face delivering their study programmes, as well as outlining the many cloud options available. The report first introduces social simulation and considers how social simulation is taught. Following this factors affecting the implementation of agent-based models are explored, with attention focused primarily on the modelling and execution platforms currently available, the challenges associated with implementing agent-based models, and the technical architectures that can be used to support the modelling, simulation and teaching process. This sets the context for an extended discussion on cloud computing including service and deployment models, accessing cloud resources, the financial implications of adopting the cloud, and an introduction to the evaluation of cloud services within the context of developing, executing and teaching agent-based models

    Organizational Posthumanism

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    Building on existing forms of critical, cultural, biopolitical, and sociopolitical posthumanism, in this text a new framework is developed for understanding and guiding the forces of technologization and posthumanization that are reshaping contemporary organizations. This ‘organizational posthumanism’ is an approach to analyzing, creating, and managing organizations that employs a post-dualistic and post-anthropocentric perspective and which recognizes that emerging technologies will increasingly transform the kinds of members, structures, systems, processes, physical and virtual spaces, and external ecosystems that are available for organizations to utilize. It is argued that this posthumanizing technologization of organizations will especially be driven by developments in three areas: 1) technologies for human augmentation and enhancement, including many forms of neuroprosthetics and genetic engineering; 2) technologies for synthetic agency, including robotics, artificial intelligence, and artificial life; and 3) technologies for digital-physical ecosystems and networks that create the environments within which and infrastructure through which human and artificial agents will interact. Drawing on a typology of contemporary posthumanism, organizational posthumanism is shown to be a hybrid form of posthumanism that combines both analytic, synthetic, theoretical, and practical elements. Like analytic forms of posthumanism, organizational posthumanism recognizes the extent to which posthumanization has already transformed businesses and other organizations; it thus occupies itself with understanding organizations as they exist today and developing strategies and best practices for responding to the forces of posthumanization. On the other hand, like synthetic forms of posthumanism, organizational posthumanism anticipates the fact that intensifying and accelerating processes of posthumanization will create future realities quite different from those seen today; it thus attempts to develop conceptual schemas to account for such potential developments, both as a means of expanding our theoretical knowledge of organizations and of enhancing the ability of contemporary organizational stakeholders to conduct strategic planning for a radically posthumanized long-term future

    EVALUATING ARTIFICIAL INTELLIGENCE FOR OPERATIONS IN THE INFORMATION ENVIRONMENT

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    Recent advances in artificial intelligence (AI) portend a future of accelerated information cycles and intensified technology diffusion. As AI applications become increasingly prevalent and complex, Special Operations Forces (SOF) face the challenge of discerning which tools most effectively address operational needs and generate an advantage in the information environment. Yet, SOF currently lack an end user–focused evaluation framework that could assist information practitioners in determining the operational value of an AI tool. This thesis proposes a practitioner’s evaluation framework (PEF) to address the question of how SOF should evaluate AI technologies to conduct operations in the information environment (OIE). The PEF evaluates AI technologies through the perspective of the information practitioner who is familiar with the mission, the operational requirements, and OIE processes but has limited to no technical knowledge of AI. The PEF consists of a four-phased approach—prepare, design, conduct, recommend—that assesses nine evaluation domains: mission/task alignment; data; system/model performance; user experience; sustainability; scalability; affordability; ethical, legal, and policy considerations; and vendor assessment. By evaluating AI through a more structured, methodical approach, the PEF enables SOF to identify, assess, and prioritize AI-enabled tools for OIE.Outstanding ThesisMajor, United States ArmyApproved for public release. Distribution is unlimited

    Aufmerksamkeitsverzerrungen in militärischen Einsatzkräften mit posttraumatischer Belastungsstörung und deren Veränderlichkeit nach Bereitstellung einer internet-basierten kognitiv-behavioralen Intervention

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    Posttraumatic stress disorder (PTSD) is a prevalent and highly disturbing mental health condition that occurs in response to extremely distressing events during the lifetime. First, military personnel represent a high-risk population for the development of posttraumatic stress symptoms (PTSS) or the full-diagnostic spectrum of the disorder due to deployment- and combat-related stressors during their military career. Despite the existence of well established and efficacious psychotherapy treatments for PTSD, access to trauma-focused psychotherapy is limited and veterans in particular experience high barriers to accessing help from the mental health care system. A substantial proportion of affected veterans receive no or inadequate treatment, increasing the risk of secondary adverse mental and somatic health outcomes, reduced social and occupational functioning, and of the condition becoming chronic. Second, internet-based interventions (IBI), particularly internet-based cognitive behavioral therapies (iCBT), have been shown to be efficacious and widely accepted for the treatment of a range of psychiatric disorders, including PTSD. IBI can already be seen as playing a potentially important role in supplementing the landscape and provision of psychotherapeutic interventions, and this is set to grow further in the future. Indeed, IBI should be particularly beneficial for patients in rural areas with a restricted psychotherapy infrastructure, for patients with restricted mobility, and for patients who desire greater anonymity and more independence regarding the time and location of psychotherapy access. Third, the systematic and reliable assessment of objective indicators of symptom expression and symptom change is of increasing interest and relevance for psychotherapy research. This dissertation thesis aims at incorporating these three pillars in four studies: First, a diagnostic identification of PTSD in veterans of the German Armed Forces (GAF) according to the main diagnostic manuals the International Classification of Diseases and Related Health Problems (ICD) and the Diagnostic and Statistical Manual of Mental Disorders (DSM); second, a meta-analytical evaluation of the efficacy of IBI in PTSD; third, an assessment of patterns of visual attentional bias in (traumatized) veterans (with PTSS); and fourth, an exploration of the modifiability of attentional bias in veterans after receiving iCBT. STUDY 1 investigated the concordance of PTSD prevalence rates when transiting between the diagnostic criteria of the DSM-IV, DSM-5, ICD-10, and proposed ICD-11 in a sample of service members of the GAF. High levels of agreement emerged between the DSM-IV and the DSM-5, and between the DSM-5 and the proposed ICD-11. Prevalence rates were significantly higher according to the proposed ICD-11 compared to the ICD-10, mainly due to the deletion of the time criterion. STUDY 1 provides support for the identification of six ‘core’ PTSD symptoms according to the proposed ICD-11, presenting a high agreement rate with the set of twenty qualifiers according to the DSM-5. STUDY 2 provided meta-analytical evidence for the efficacy of IBI for the treatment of PTSD. Twenty randomized controlled trials (RCT) encompassing 21 comparisons were included, evaluating either iCBT or internet-based expressive writing (iEW) with passive or active control conditions. The results revealed that iCBT was more efficacious than passive control conditions at post-treatment assessment (0.66 ≤ g ≤ 0.83). No superiority of either iCBT or iEW was found in contrast to active control conditions. Subgroup analyses revealed no significant moderators of iCBT efficacy. More research is needed to prove the efficacy of IBI in contrast to active control treatments and further explore the impact of moderators on treatment efficacy. STUDY 3 measured patterns of attentional bias in GAF veterans with PTSS, traumatized veterans without PTSS, and unexposed healthy veterans. In a free-viewing task, participants were presented with pairs of combat-related and neutral pictures, of more general threat-related and neutral pictures, and of emotional and neutral faces, while their eye gazes were tracked. Further, the internal consistency of attentional bias indicators was calculated. The findings provide support for the maintenance hypothesis in PTSS. There was no robust evidence to support the hypothesis of hypervigilant behavior in PTSS. Findings on attentional bias variability remain unclear. Internal consistency varied across attentional bias indicators, highlighting the need for future research in this regard. STUDY 4 investigated the modifiability of attentional bias in veterans with PTSS through the provision of iCBT. In a free-viewing task, participants were presented with combat-related, general threat-related, and neutral pictures, and with faces with negative emotional valence and neutral facial expressions while their eye gazes were tracked. Attentional bias was examined pre- and post-intervention and at a three-month follow-up. No modifications in attentional bias were observable over time. Future investigations are warranted to systematically investigate objective measures of symptom expression and symptom change together with subjective symptom reporting and symptom change in response to psychotherapeutic treatment options. In summary, this dissertation thesis provides a threefold contribution to the current landscape of psychotherapy research: First, it supports the concordance between the DSM-5 and the ICD-11 diagnostic criteria for PTSD. Second, it proves the efficacy of IBI for PTSD. In view of the growing relevance of IBI as a supplement to psychotherapeutic care, future research needs to examine its long-term efficacy, whether it shows equal or superior efficacy compared to other active (control) treatments, potential side effects, and whether it may lead to a deterioration of symptoms. Moreover, studies should focus on tailoring IBI to the specific needs of different patient populations to ensure patients’ safety and satisfaction with IBI. Third, the present thesis underlines the need for systematic and reliable assessments of objective indicators of symptom presentation and of symptom change, in addition to subjective reports. Moreover, methodological approaches need to be extended to measure diverse dimensions of symptom presentation and symptom change and gain a better understanding of their interplay. A multidimensional diagnostic approach and treatment evaluation will be of key relevance for future intervention research and evidence-based practice

    Parasocial While Meaningful: How Does Exposure to Foreign Cultures Affect One\u27s Opinion of Foreign Countries?

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    This dissertation attempts to study how exposure to foreign cultures affects one’s opinion of foreign countries. According to the parasocial contact theory, indirect mediated contact with an outgroup member on screen, similar to direct face-to-face contact, can reduce ingroup bias and outgroup prejudice. However, the parasocial contact effect is conditioned by the media content and producer. I argue that the consumption of foreign-made cultural products, such as TV programs and movies, is a better alternative and categorize it into two types. First, group-specific exposure to a foreign culture is associated with decategorization that strengthens knowledge, affinity, empathy, and identification with the contacted outgroup media character and deemphasizes group-based categorical differences. Second, generalized exposure to diverse foreign cultures contributes to recategorization through which a more inclusive, shared superordinate identity is constructed beyond subgroup boundaries and ingroup members become more cosmopolitan. Both approaches are hypothesized to lead to more favorable attitudes toward foreign countries. Drawing upon the AsiaBarometer Survey and East Asian Social Survey, the overall statistical analyses lend empirical support to the positive effects of group-specific and generalized cultural exposure. Using cable TV ownership as an instrument, the instrumental variable and corresponding sensitivity analyses further add to the robustness of the above findings
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