15933972
A logical specification for usage control
Recently presented usage control (UCON) has been considered as the next generation access control model with distinguishing properties of decision continuity and attribute mutability. Ausage control decision is determined by combining authorizations, obligations, and conditions, presented as UCONABC core models by Park and Sandhu. Based on these core aspects, we develop afirst-order logic specification of UCON with Lamport's temporallogic of actions (TLA). The building blocks of this model include:(1) a sequence of states expressed by attributes of subjects, objects, and the system, (2) state predicates on subject andobject attributes, (3) pre-defined authorization actions performed by the security system and subjects, (4) obligation actions, and(5) condition predicates on system attributes. For a UCON model we define a set of temporal logic formulas that hold as usage control policies. We show the flexibility and expressive capability of this logic model by specifying the new features and core models of UCON.
15806644
Attribute Mutability in Usage Control
The notion of Usage Control (UCON) has been introduced recently to extend traditional access controls by including three decision factors called authorizations, obligations, and conditions. Usage control also recognize two important decision properties of continuity and mutability. In access control literature, an authorization decision is commonly made by utilizing some form of subject and object attributes. Identities, security labels and roles are some examples of attributes. Traditionally these attributes are assigned to subjects and objects by a security officer and can be modified only by administrative actions. However, in modern information systems these attributes are often required to be changed as a side effect of subject’s usage on object. This requirement of updates has been recognized and defined as mutability property in usage control. In this paper, we discuss issues of this attribute mutability and show how usage control can apply this mutability property in various traditional and modern access control policies.
11119047
Component-abnormality detection and immunization for survivable systems in large distributed environments
17481727
Strain analysis and visualization: left ventricle of a heart
Abstract Clinical utility of computational models is crucial in the applications of medical data visualization. Previously we have developed a new class of volumetric models whose parameters are functions in conjunction with physically based deformable modeling framework, and have applied the technique to estimate the left ventricular (LV) wall motion. We have successfully showed that the model parameter functions characterize the LV motion of normal and abnormal states and that no further non-trivial post-processing is required for anatomically meaningful interpretation. In an effort to evaluate the LV model, this paper presents a method and results from a strain analysis based on the nodal displacements of the deformable LV model. Furthermore, in order to visualize the local quantities on the volumetric model for an effective analysis, we also developed a methodology to assist in assessing the cardiac function utilizing principal strains, Von-Mises’ yield criteria, and a smoothing filter. Each strain tensor component was in the range of values observed in other reported studies. The application of a smoothing filter on the model improved in visualizing the overall trend of each strain variation. With our platform for a comprehensive strain analysis, we have augmented a clinical utility to the deformable models with parameter functions.
6952634
A middleware approach for SAINT (secure, automatic, interoperable, and transparent) peer-to-peer content services
Expanded use of the Internet and technological advances are eliciting changes in how individuals manage and share their contents. The Internet has been primarily a client-server-based system, where it is challenging to keep contents up-to-date and consistent among all of the devices. Furthermore, the client-server model has service limitations in heterogeneous computing environments. However, a new peer-to-peer (P2P) model has emerged. In this P2P workplace, each participant (peer) acts as both client and content provider. Compared with services performed by the client-server model, P2P-based content management services have several advantages. In P2P environments, users can manage heterogeneous information resources residing in various platforms perhaps in different policy environments. A P2P-based content management model can provide higher resource availability due to the distributed nature of P2P computing. However, wide-scale application of P2P computing is constrained by limitations associated with the especially sophisticated control mechanisms needed between peers: most current P2P technologies simply focus on sharing services rather than on controls between the peers. In this paper, we introduce a middleware approach to support the underlying mechanisms, providing secure, automatic, interoperable, and transparent (SAINT) services for P2P content management. The underlying mechanisms are based on machine-understandable metadata. Our middleware approach using metadata facilitates the SAINT content management services with rich metadata expression in P2P computing environments. The broad dissemination of our approach allows the application of P2P technology to more reliable and efficient content services within organization or inter-organizations.
8794763
Video Retrieval of Human Interactions Using Model-Based Motion Tracking and Multi-layer Finite State Automata
Recognition of human interactions in a video is useful for video annotation, automated surveillance, and content-based video retrieval. This paper presents a model-based approach to motion tracking and recognition of human interactions using multi-layer finite state automata (FA). The system is used for widely-available, static-background monocular surveillance videos. A three-dimensional human body model is built using a sphere and cylinders and is projected on a two-dimensional image plane to fit the foreground image silhouette. We convert the human motion tracking problem into a parameter optimization problem without the need to compute inverse kinematics. A cost functional is used to estimate the degree of the overlap between the foreground input image silhouette and a projected three-dimensional body model silhouette. Motion data obtained from the tracker is analyzed in terms of feet, torso, and hands by a behavior recognition system. The recognition model represents human behavior as a sequence of states that register the configuration of individual body parts in space and time. In order to overcome the exponential growth of the number of states that usually occurs in single-level FA, we propose a multi-layer FA that abstracts states and events from motion data at multiple levels: low-level FA analyzes body parts only, and high-level FA analyzes the human interaction. Motion tracking results from video sequences are presented. Our recognition framework successfully recognizes various human interactions such as approaching, departing, pushing, pointing, and handshaking.
31766769
Improved selection in totally monotone arrays
This paper's main result is an -time algorithm for computing the kth smallest entry in each row of an m×n totally monotone array. (A two-dimensional array A={a[i, j]} is totally monotone if for all i1<i2 and j1<j2, a[i1, j1]<a[i1, j2] implies a[i2, j1]<a[i2, j2].) For large values of k (in particular, for k=⌈n/2⌉), this algorithm is significantly faster than the O(k(m + n))-time algorithm for the same problem due to Kravets and Park. An immediate consequence of this result is an O(n3/2lg1/2 n)-time algorithm for computing the kth nearest neighbor of each vertex of a convex n-gon. In addition to the main result, we also give an O(n lg m)-time algorithm for computing an approximate median in each row of an m×n totally monotone array; this approximate median is an entry whose rank in its row lies between ⌊n/4⌋ and ⌈3n/4⌉ − 1.