National Security Agency

About: National Security Agency is a government organization based out in Fort George Meade, Maryland, United States. It is known for research contribution in the topics: Signal & Encryption. The organization has 393 authors who have published 485 publications receiving 15916 citations. The organization is also known as: NSA & N.S.A..

Range limited antenna

Abstract: Range limited antenna includes at least two sets of antenna elements and an RF signal processing network connected to each set of antenna elements. The network has a function, F(Ξ,x)=ΦA(x)−ΦB(x)+ΦC(x)−ΦD(x) . . . +ΦN−1(x)−ΦN(x), where x is a signal, ΦA(x) is the phase angle of signal x at the first element set, ΦB(x) is the phase angle of signal x at the second element set, ΦN(x) is the phase angle of signal x at the set N, and Ξ contains all additional parameters which bear on the system. The network is configured to pass a signal for which F(Ξ,x)>e, where e is a threshold amount, such that the antenna has gain to signals within a radius and has attenuation outside the radius.

Split Euler Tours In 4-Regular Planar Graphs

Abstract: Abstract The construction of a homing tour is known to be NP-complete. On the other hand, the Euler formula puts su cient restrictions on plane graphs that one should be able to assert the existence of such tours in some cases; in particular we focus on split Euler tours (SETs) in 3-connected, 4-regular, planar graphs (tfps). An Euler tour S in a graph G is a SET if there is a vertex v (called a half vertex of S) such that the longest portion of the tour between successive visits to v is exactly half the number of edges of G. Among other results, we establish that every tfp G having a SET S in which every vertex of G is a half vertex of S can be transformed to another tfp G′ having a SET S′ in which every vertex of G′ is a half vertex of S′ and G′ has at most one point having a face configuration of a particular class. The various results rely heavily on the structure of such graphs as determined by the Euler formula and on the construction of tfps from the octahedron. We also construct a 2-connected 4-regular planar graph that does not have a SET.

Database Security 2000

Abstract: Database systems are being more and more used, with larger sized databases, and as components of very complex systems, that include numerous protocols. Database security problems in the past have only partially been solved. Is there any hope to provide adequate security for the new database systems? This paper describes user and system requirements and provides a list of hints and techniques to better secure this type of system.

System and method for automated reasoning with and searching of documents

Abstract: A method and computer system architecture for providing to a computer user or to a downstream system a means of converting the content of documents including legal, policy, and compliance statements, using symbolic logic, into a logic ontology, which enables users to reason through the content of laws, policies, and procedures by means of automated reasoning. The system additionally includes a process for easily searching or navigating multiple facets of legal, policy, and compliance documents.

Lower bounds for codimension-1 measure in metric manifolds

Abstract: We establish Euclidean-type lower bounds for the codimension-1 Hausdorff measure of sets that separate points in doubling and linearly locally contractible metric manifolds. This gives a quantitative topological isoperimetric inequality in the setting of metric manifolds, in the sense that lower bounds for the codimension-1 measure of a set depend not on some notion of filling or volume but rather on in-radii of complementary components. As a consequence, we show that balls in a closed, connected, doubling, and linearly locally contractible metric $n$-manifold $(M,d)$ with radius $0 0$ depends only on $n$ and on the doubling and linear local contractibility constants.