The paper presents the evaluation of knowledge of the subject of computing and informatics of the first year students of Gymnasium high school. The knowledge test was particularly designed for this purpose. The main o...
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The paper presents the evaluation of knowledge of the subject of computing and informatics of the first year students of Gymnasium high school. The knowledge test was particularly designed for this purpose. The main objective of the research is to determine the level of acquired knowledge of computing and informatics. The research evaluated 362 first grade Gymnasium students from three cities in Serbia: Cacak, Kraljevo and Uzice. As the result of this study, and due to the constant changes in Information Technology (IT), the authors suggest a complete reconstruction of the IT curriculum for the first year of Gymnasium, and an update of the existing curriculum every two to three years.
This paper addresses the challenge of accommodating nonlinear dynamics and constraints in rapid trajectory optimization with impulsive maneuvers, envisioned for use in the context of onboard guidance. We present a nov...
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This paper addresses the challenge of accommodating nonlinear dynamics and constraints in rapid trajectory optimization with impulsive maneuvers, envisioned for use in the context of onboard guidance. We present a novel framework that uniquely employs overparameterized monomial coordinates and precomputed fundamental solution expansions to facilitate rapid optimization while minimizing real-time computational requirements. The fundamental solution expansions are precomputed about an uncontrolled reference trajectory using differential algebra. Unlike traditional approaches that repeatedly evaluate the nonlinear dynamics and constraints as part of complex shooting or collocation-based schemes, this method replaces the nonlinearity inherent to dynamics and constraint functions entirely with a computationally simpler manifold constraint. With this approach, trajectory optimization is posed efficiently as a path-planning problem on the manifold. This problem is entirely convex except for the manifold constraint, readily lending itself to solution via sequential convex programming. We demonstrate the effectiveness of our approach in computing fast and accurate Delta V optimal solutions for long-range spacecraft rendezvous, including problems with nonlinear state constraints.
Efficient band-structure calculations are essential for understanding the mechanical behaviors of periodic materials, with significant implications in material design and phononic engineering. This paper introduces th...
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Efficient band-structure calculations are essential for understanding the mechanical behaviors of periodic materials, with significant implications in material design and phononic engineering. This paper introduces the application of the improved reduced system (IRS) technique to expedite elastic band-structure calculations. The IRS, a dynamic condensation method, partitions the unit cell degrees of freedom (DOFs) into primary and secondary sets. A strategic selection of primary DOFs retains a subset of interior DOFs alongside all exterior DOFs while truncating the remaining interior DOFs. The integration of IRS with the Craig-Bampton method for additional reduction and the imposition of Bloch boundary conditions yields a notable decrease in computational overhead. Additionally, for structures with a high number of interior DOFs, a substructuring scheme can be implemented to further enhance efficiency. This approach offers a compelling combination of accuracy and expedited computation, making it applicable across diverse periodic materials.
Jupiter's icy moon Europa is among the most promising locations to explore for signs of extraterrestrial life in our solar system. However, searching for biosignatures on the surface of Europa presents an unpreced...
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Jupiter's icy moon Europa is among the most promising locations to explore for signs of extraterrestrial life in our solar system. However, searching for biosignatures on the surface of Europa presents an unprecedented set of challenges: immense uncertainty, limited energy, and few opportunities for operator feedback. Effectively carrying out a robotic science campaign under these conditions will require a system with a greater degree of autonomy than any planetary exploration mission to date. In particular, onboard scheduling and execution are required for robustness to uncertainty in surface conditions, variation in lander performance, and science discoveries to maximize the quantity and quality of science data returned to Earth during a fixed, limited lander lifetime. Here we represent a proposed Europa Lander surface mission as a utility-driven hierarchical task network and establish through analysis that onboard autonomy using automated mission planning with execution feedback and predictive task models results in mission execution that is more consistently productive compared to traditional static approaches. We design a simulated onboard autonomy framework built by integrating two software components-Multi-mission EXECutive and Europa Lander Autonomy Prototype-to properly simulate the Europa Lander domain and demonstrate empirically that the proposed planning and execution system is capable of commanding a set of realistic surface scenarios as part of a larger Europa Lander surface autonomy software prototype. We expect that an approach to scheduling and execution grounded in decision theory will be an enabling technology for future tightly constrained planetary surface missions.
To ensure the safe and efficient operation of flights in terminal maneuvering areas, airports establish standard arrival and departure procedures. However, designing these procedures is typically time-consuming and ch...
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To ensure the safe and efficient operation of flights in terminal maneuvering areas, airports establish standard arrival and departure procedures. However, designing these procedures is typically time-consuming and challenging for quantitative path length optimization. This paper presents an efficient optimization method for designing multiple arrival and departure procedures, taking into account the configuration of the airport and the nearby environment. The objective is to minimize the total length of routes while satisfying related operational constraints, such as obstacle avoidance and route separation. Each route is modeled in three dimensions, consisting of a horizontal polygonal line and a vertical cone. Considering the actual procedures' merging or diverging configuration characteristics, multiple arrival or departure routes are then modeled as a tree-like topology structure. A hybrid algorithm, integrating simulated annealing and an improved A* algorithm, is developed for automated problem-solving. Simulation results, based on tests at Sweden's Arlanda Airport, exhibit advantages over existing related research in terms of both total route length and computing time. Tests at Shanghai Pudong Airport show an 8% reduction in total path length compared to actual procedures, demonstrating the proposed method's effectiveness and potential contributions to energy savings and emissions reduction.
A direct solution approach for surface erosion in particle-laden hypersonic flows is extended for use in low-cost twoway coupled solutions of dilute gas-particle flows. The trajectory control volume method, which uses...
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A direct solution approach for surface erosion in particle-laden hypersonic flows is extended for use in low-cost twoway coupled solutions of dilute gas-particle flows. The trajectory control volume method, which uses a sparse set of probe particles to predict surface erosion distributions on general vehicles, is reformulated for the solution of source terms by mean trajectory subdivision and computing a flux differencing. The approach is verified successfully against a boundary-layer solution and shown to agree well with experimental measurements. A representative Mars entry case, with conditions and geometry based on the ExoMars Schiaparelli capsule, is solved with the approach to study the impact of two-way coupling on surface heating and erosion. Results indicate that, for realistic loading conditions, heating is largely unmodified compared to one-way coupled results at peak heating trajectory conditions, and no measureable difference is observed in the surface erosion rate. At exaggerated loading conditions high enough to observe coupling effects, the worst-case collisional heating can increase heating by up to 60%.
Ever since its inception, cryptography has been caught in a vicious circle: Cryptographers keep inventing methods to hide information, and cryptanalysts break them, prompting cryptographers to invent even more sophist...
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Ever since its inception, cryptography has been caught in a vicious circle: Cryptographers keep inventing methods to hide information, and cryptanalysts break them, prompting cryptographers to invent even more sophisticated encryption schemes, and so on. But could it be that quantum information technology breaks this circle? At first sight, it looks as if it just lifts the competition between cryptographers and cryptanalysts to the next level. Indeed, quantum computers will render most of today's public key cryptosystems insecure. Nonetheless, there are good reasons to believe that cryptographers will ultimately prevail over cryptanalysts. Quantum cryptography allows us to build communication schemes whose secrecy relies only on the laws of physics and some minimum assumptions about the cryptographic hardware-leaving basically no room for an attack. While we are not yet there, this paper provides an overview of the principles and state-of-the-art of quantum cryptography, as well as an assessment of current challenges and prospects for overcoming them.
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