768 research outputs found
Dead Reckoning Using Play Patterns in a Simple 2D Multiplayer Online Game
In today’s gaming world, a player expects the same play experience whether playing on a local network or online with many geographically distant players on congested networks. Because of delay and loss, there may be discrepancies in the simulated environment from player to player, likely resulting in incorrect perception of events. It is desirable to develop methods that minimize this problem. Dead reckoning is one such method. Traditional dead reckoning schemes typically predict a player’s position linearly by assuming players move with constant force or velocity. In this paper, we consider team-based 2D online action games. In such games, player movement is rarely linear. Consequently, we implemented such a game to act as a test harness we used to collect a large amount of data from playing sessions involving a large number of experienced players. From analyzing this data, we identified play patterns, which we used to create three dead reckoning algorithms. We then used an extensive set of simulations to compare our algorithms with the IEEE standard dead reckoning algorithm and with the recent “Interest Scheme” algorithm. Our results are promising especially with respect to the average export error and the number of hits
NASA SBIR abstracts of 1991 phase 1 projects
The objectives of 301 projects placed under contract by the Small Business Innovation Research (SBIR) program of the National Aeronautics and Space Administration (NASA) are described. These projects were selected competitively from among proposals submitted to NASA in response to the 1991 SBIR Program Solicitation. The basic document consists of edited, non-proprietary abstracts of the winning proposals submitted by small businesses. The abstracts are presented under the 15 technical topics within which Phase 1 proposals were solicited. Each project was assigned a sequential identifying number from 001 to 301, in order of its appearance in the body of the report. Appendixes to provide additional information about the SBIR program and permit cross-reference of the 1991 Phase 1 projects by company name, location by state, principal investigator, NASA Field Center responsible for management of each project, and NASA contract number are included
Advanced Integration of GNSS and External Sensors for Autonomous Mobility Applications
L'abstract è presente nell'allegato / the abstract is in the attachmen
State of the art of cyber-physical systems security: An automatic control perspective
Cyber-physical systems are integrations of computation, networking, and physical processes. Due to the tight cyber-physical coupling and to the potentially disrupting consequences of failures, security here is one of the primary concerns. Our systematic mapping study sheds light on how security is actually addressed when dealing with cyber-physical systems from an automatic control perspective. The provided map of 138 selected studies is defined empirically and is based on, for instance, application fields, various system components, related algorithms and models, attacks characteristics and defense strategies. It presents a powerful comparison framework for existing and future research on this hot topic, important for both industry and academia
Aeronautical engineering: A continuing bibliography with indexes (supplement 259)
This bibliography lists 774 reports, articles, and other documents introduced into the NASA scientific and technical information system in November, 1990. Subject coverage includes: design, construction and testing of aircraft and aircraft engines; aircraft components, equipment and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics
Smart metering and its use for distribution network control
Global energy demand is increasing, with the adoption of electric vehicles, in particular, representing a significant prospective demand on electricity distribution networks. The exploitation of renewable generation sources, driven by increased economic viability, technological maturity, and the need for environmental sustainability, is expected to play an increasingly important role in meeting this demand. However, the adoption of such low-carbon technologies necessitates a significant change in the way that distribution networks are monitored and controlled. This work examines the state of the art in the impact of low-carbon technologies on distribution networks, the technical strategies available to mitigate these impacts and their relative merits, and the architecture of the control systems used to effect such strategies. Smart metering and advanced metering infrastructure (AMI) are a fundamental component of these smart grid systems, providing widespread visibility of conditions at the very periphery of distribution networks which has not previously been feasible, but where the impact of low-carbon technologies is significant. This work describes the development of a hardware-in-the-loop test rig incorporating multiple, custom-built, hardware smart meter test beds, and the use of this test rig to demonstrate the implementation of real-time voltage control within a simulated low voltage (LV) distribution network. However, the adoption of smart metering and AMI inevitably incurs cyber security vulnerabilities which did not exist in the case of meters with no facility for remote communication. This work examines cyber security issues pertinent to smart grids and AMI in particular, and describes the analysis of the cyber security vulnerabilities of a commercially deployed smart electricity meter. The exploitation of these vulnerabilities in a manner which permits unauthorised electronic access to the device is also described. Finally, recommendations are made of revisions to the hardware, firmware and communications protocols used by the compromised meter which may mitigate the vulnerabilities identified
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A comprehensive proposal for securing terrestrial radionavigation systems
The security of terrestrial radionavigation systems (TRNS) has not yet been addressed in the literature. This proposal builds on what is known about securing global navigation satellite systems (GNSS) to address this gap, re-evaluating proposals for GNSS security in light of the distinctive properties of TRNS. TRNS of the type envisioned in this paper are currently in their infancy, unburdened by considerations of backwards compatibility: security for TRNS is a clean slate. This thesis argues that waveform- or signal-level security measures are irrelevant for TRNS, preventing neither spoofing nor unauthorized use of the service. Thus, only security measures which modify navigation message bits merit consideration. This thesis proposes orthogonal mechanisms combining navigation message encryption (NME) and navigation message authentication (NMA), constructed from standard cryptography primitives and specialized to TRNS: message encryption allows providers to offer tiered access to navigation parameters on a bit-by-bit basis, and message authentication disperses the bits of a message authentication code across all data packets, posing an additional challenge to spoofers. This cryptographic proposal, however, is still vulnerable to certain types of replay threats. This thesis addresses this gap by augmenting TRNS with autonomous signal-situational-awareness (SSA) capability, allowing TRNS operators to detect spoofing and meaconing attacks. Two signal authentication techniques for SSA are developed to detect a weak spoofing signal in the presence of static and dynamic multipath. This thesis also proposes enhancements to these signal authentication techniques. These enhancements exploit the synergy from combining information across multiple epochs, or over multiple monitoring beacons, to further lower the spoofer detection threshold. Both techniques with their enhancements are shown to be effective in simulations of the varied operating environments that a generic TRNS will encounter. With both proposed cryptographic NME+NMA scheme and autonomous SSA in place, TRNS gains a defensive capability that GNSS cannot easily match: a comprehensive defense against most man-in-the-middle attacks on position, navigation and timing services.Aerospace Engineerin
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