Guidance and flight control law development for hypersonic vehicles

During the third reporting period our efforts were focused on a reformulation of the optimal control problem involving active state-variable inequality constraints. In the reformulated problem the optimization is carried out not with respect to all controllers, but only with respect to asymptotic controllers leading to the state constraint boundary. Intimately connected with the traditional formulation is the fact that when the reduced solution for such problems lies on a state constraint boundary, the corresponding boundary layer transitions are of finite time in the stretched time scale. Thus, it has been impossible so far to apply the classical asymptotic boundary layer theory to such problems. Moreover, the traditional formulation leads to optimal controllers that are one-sided, that is, they break down when a disturbance throws the system on the prohibited side of the state constraint boundary

Rapid near-optimal aerospace plane trajectory generation and guidance

Effort was directed toward the problems of the real time trajectory optimization and guidance law development for the National Aerospace Plane (NASP) applications. In particular, singular perturbation methods were used to develop guidance algorithms suitable for onboard, real time implementation. The progress made in this research effort is reported

Understanding the Nature of Entrepreneurial Leadership in the Startups Across the Stages of the Startup Lifecycle

Start-ups are important part of the world economy. Despite the astonishing rate of the start-up creation, their viability and success remain to be relatively low. Reasons behind the failure are diverse and complex. The leadership has been recognized as an important factor influencing the performance of start-ups. The paper argues that entrepreneurial leadership theory can effectively capture the complex processes in start-ups. Τhe paper explores a broader understanding of the entrepreneurial leadership by examining the context around which the entrepreneurial leadership occurs. Additionally, it includes leader and follower perspective in constructing the phenomenon. Lastly, the research reveals that it is important to view the Entrepreneurial leadership as a process developing along the stages of the start-up life cycle. The findings suggest that leadership is changing across the lifespan of the start-ups and distinct conditions and features are characteristic for the entrepreneurial leadership within each respective stage

Finger tracking and hand recognition technologies in virtual reality maritime safety training applications

The competitiveness and development of the maritime sector together with the continuous effort on increasing operations performance while reducing operations costs, drives the needs for on-board effective and qualitative training safety related issues. Virtual reality (VR) has been considered by classification societies and training organizations as a technology that can significantly improve seafarer's performance and competence with the adaptation of maritime applications developed for design simulation and gaming. This paper presents the evolution of the MarSEVR (Maritime Safety Education with VR) technology as a new concept and technology by integrating finger tracking and hand recognition technologies that increase immersiveness and user engagement within the MarISOT technology, a Green Ocean innovation composed of VR safety applications. The paper approaches this integration by addressing game design, pedagogic and cognitive neuroscience principles and challenges on the use of hand recognition and finger tracking in the MarSEVR learning episodes

Eye tracking in maritime immersive safe oceans technology

This paper presents the integration of eye tracking in the MarSEVR (Maritime Safety Education with VR) technology to increase the precision of the trainee focus on delivering the learning episodes of the technology with enhanced impressiveness and user engagement. MarSEVR is part of the Safe Oceans concept, a green ocean technology that integrates several VR safety training applications to reduce maritime accidents that result into human casualties, sea pollution and other environmental damages. The paper indicates the research delivery architecture driven by Hevner's design science in information systems Research for usability, use experience (UX) and effectiveness. Furthermore, this technology integration is approached from a game design perspective for user engagement but also from a cognitive and neuroscience perspective for pedagogical use and purposes. The paper addressees the impact of the eye tracking technology in the maritime sector operations, training market, and competitive research. Lastly areas of further research are presented and the efforts to link and align finger tracking and hand recognitions technologies with eye tracking for a more complete VR training environment

Postnatal Development of Dendrodendritic Inhibition in the Mammalian Olfactory Bulb

The mitral–granule cell (MC–GC) reciprocal synapse is an important source of auto- and lateral-inhibition in the olfactory bulb (OB), and this local inhibition is critical for odor discrimination. We may gain insight into the role of MC autoinhibition in olfaction by correlating the functional development of the autoinhibition with the postnatal development of olfactory function. We have studied the functional development of the MC–GC reciprocal synapse using whole-cell patch-clamp recordings from MCs and GCs in acute OB slices from 3- to 30-day-old rats. The magnitude of dendrodendritic inhibition (DDI) measured by depolarizing a single MC and recording recurrent inhibition in the same cell increased up to the fifteenth day of life (P15), but dropped between P15 and P30. The initial increase and later decrease in DDI was echoed by a similar increase and decrease in the frequency of miniature inhibitory post-synaptic currents, suggesting an accompanying modulation in the number of synapses available to participate in DDI. The late decrease in DDI could also result, in part, from a decrease in GC excitability as well as an increase in relative contribution of N-methyl d-aspartate (NMDA) receptors to γ-amino butyric acid (GABA) release from GC synapses. Changes in release probability of GABAergic synapses are unlikely to account for the late reduction in DDI, although they might contribute to the early increase during development. Our results demonstrate that the functional MC–GC circuit evolves over development in a complex manner that may include both construction and elimination of synapses

Functional Properties of Cortical Feedback Projections to the Olfactory Bulb

SummarySensory perception is not a simple feed-forward process, and higher brain areas can actively modulate information processing in “lower” areas. We used optogenetic methods to examine how cortical feedback projections affect circuits in the first olfactory processing stage, the olfactory bulb. Selective activation of back projections from the anterior olfactory nucleus/cortex (AON) revealed functional glutamatergic synaptic connections on several types of bulbar interneurons. Unexpectedly, AON axons also directly depolarized mitral cells (MCs), enough to elicit spikes reliably in a time window of a few milliseconds. MCs received strong disynaptic inhibition, a third of which arises in the glomerular layer. Activating feedback axons in vivo suppressed spontaneous as well as odor-evoked activity of MCs, sometimes preceded by a temporally precise increase in firing probability. Our study indicates that cortical feedback can shape the activity of bulbar output neurons by enabling precisely timed spikes and enforcing broad inhibition to suppress background activity

Diamond grinding wheels production study with the use of the finite element method

AbstractResearch results on 3D modeling of the diamond grain and its bearing layer when sintering diamond grinding wheels are provided in this paper. The influence of the main characteristics of the wheel materials and the wheel production process, namely the quantity of metallic phase within diamond grain, coefficient of thermal expansion of the metallic phase, the modulus of elasticity of bond material and sintering temperature, on the internal stresses arising in grains is investigated. The results indicate that the stresses in the grains are higher in the areas around the metallic phase. Additionally, sintering temperature has the greatest impact on the stresses of the grain-metallic phase-bond system regardless of the type of the bond. Furthermore, by employing factorial design for the carried out finite element model, a mathematical model that reflects the impact of these factors on the deflected mode of the diamond grain-metallic phase-bond material system is obtained. The results of the analysis allow for the identification of optimal conditions for the efficient production of improved diamond grinding wheels. More specifically, the smallest stresses are observed when using the metal bond with modulus of elasticity 204GPa, the quantity of metallic phase in diamond grain of not higher than 7% and coefficient of thermal expansion of 1.32×10−51/K or lower. The results obtained from the proposed 3D model can lead to the increase in the diamond grains utilization and improve the overall efficiency of diamond grinding