Opin vísindi

 

Nýlega bætt við

Verk
Improved heuristics for optimal pathfinding on game maps
(AAAI Press, 2006) Björnsson, Yngvi; Halldórsson, Káari; Department of Computer Science
As computer game worlds get more elaborate the more visible pathfinding performance bottlenecks become. The heuristic functions typically used for guiding A*- based pathfinding are too simplistic to provide the search with the necessary guidance in such large and complex game worlds. This may result in A*-search exploring the entire game map in order to find a path between two distant locations. This article presents two effective heuristics for estimating distances between locations in large and complex game maps. The former, the dead-end heuristic, eliminates from the search map areas that are provably irrelevant for the current query, whereas the second heuristic uses so-called gateways to improve its estimates. Empirical evaluation on actual game maps shows that both heuristics reduce the exploration and time complexity of A* search significantly over a standard octile distance metric.
Verk
Solving 7×7 Hex : Virtual connections and game-state reduction
(Springer New York LLC, 2004) Hayward, R.; Björnsson, Y.; Johanson, M.; Kan, M.; Po, N.; van Rijswijck, J.; Department of Computer Science
We present an algorithm which determines the outcome of an arbitrary Hex game-state by finding a winning virtual connection for the winning player. Our algorithm performs a recursive descent search of the game-tree, combining fixed and dynamic game-state virtual connection composition rules with some new Hex game-state reduction results based on move domination. The algorithm is powerful enough to solve arbitrary 7×7 game-states; in particular, we use it to determine the outcome of a 7 × 7 Hex game after each of the 49 possible opening moves, in each case finding an explicit proof-tree for the winning player.
Verk
Differences in epicentral location of Mexican earthquakes between local and global catalogs : An update
(2016) Hjörleifsdóttir, Vala; Singh, Shri Krishna; Husker, Allen; Department of Engineering
Differences in epicentral locations between local and global catalogs for earthquakes in the Mexican subduction zone were first observed to be biased in the 1980s, based on a few well studied events. In this study we compare locations between two local catalogs; (1) a recent high precision catalog of events in the state of Guerrero and (2) the catalog of the Servicio Sismológico Nacional (SSN), to the global catalog of the United States Geological Service (USGS). We find that on average epicentral locations in the global catalog of earthquakes larger than M 5 in the Mexican subduction zone are 26 km towards N54°E of those in the local catalogs. We investigate how the errors vary for different types of earthquakes in Guerrero, and how they vary along the trench, from the state of Jalisco to the state of Chiapas. The average differences are largest for thrust events occurring close to the trench, and for events in Michoacán. The differences are greater on average for large earthquakes than for small. There is a tradeoff between the distance from the trench and timing, suggesting a poor resolution of these parameters, due to the lack of stations the Pacific Ocean. We attribute the differences in locations to systematic patterns in the velocity structure of the mantle, with consistently fast paths to the northeast and relatively slow paths towards the southwest.
Verk
Building the checkers 10-piece endgame databases
(Springer New York LLC, 2004) Schaeffer, J.; Björnsson, Y.; Burch, N.; Lake, R.; Lu, P.; Sutphen, S.; Department of Computer Science
In 1993, the CHINOOK team completed the computation of the 2 through 8- piece checkers endgame databases, consisting of roughly 444 billion positions. Until recently, nobody had attempted to extend this work. In November 2001, we began an effort to compute the 9- and 10-piece databases. By June 2003, the entire 9-piece database and the 5-piece versus 5-piece portion of the 10-piece database were completed. The result is a 13 trillion position database, compressed into 148 GB of data organized for real-time decompression. This represents the largest endgame database initiative yet attempted. The results obtained from these computations are being used to aid an attempt to weakly salve the game. This paper describes our experiences working on building large endgame databases.
Verk
Efficient key management system for large-scale smart RFID applications
(2015) Sadikin, Mohammad Fal; Kyas, Marcel; Department of Computer Science
Due to low-cost and its practical solution, the integration of RFID tag to the sensor node called smart RFID has become prominent solution in various fields including industrial applications. Nevertheless, the constrained nature of smart RFID system introduces tremendous security and privacy problem. One of them is the problem in key management system. Indeed, it is not feasible to recall all RFID tags in order to update their security properties (e.g. update their private keys). On the other hand, using common key management solution like standard TLS/SSL is too heavy-weight that can drain and overload the limited resources. Furthermore, most of existing solutions are highly susceptible to various threats reaching from privacy threats, physical attacks to various technics of Man-in-the-Middle attacks. This paper introduces novel key management system, tailored to the limited resources of smart RFID system. It proposes light-weight mutual authentication and identity protection to mitigate the existing threats.

Flokkar í Opnum vísindum

Veldu flokk til að skoða.

Niðurstöður 1 - 9 af 9