31254944
Priority Scheduling in Wireless Ad Hoc Networks
Ad hoc networks formed without the aid of any established infrastructure are typically multi-hop networks. Location dependent contention and hidden terminal problem make priority scheduling in multi-hop networks significantly different from that in wireless LANs. Most of the prior work related to priority scheduling addresses issues in wireless LANs. In this paper, priority scheduling in multi-hop networks is discussed. We propose a scheme using two narrow-band busy tone signals to ensure medium access for high priority source stations. The simulation results demonstrate the effectiveness of the proposed scheme.
1335433
A wakeup scheme for sensor networks: achieving balance between energy saving and end-to-end delay
Energy saving is a critical task for sensor networks with limited energy supply. Wakeup schemes that turn off sensors' radio when communication is not necessary have great potential in energy saving. However, existing wakeup schemes encounter critical tradeoffs between energy saving and wakeup latency, and little attention has been paid to reducing the packet end-to-end delay while preserving the energy saving capability. We argue that a long delay can be detrimental for large sensor networks. We propose a wakeup scheme that helps to achieve the balance between energy saving and end-to-end delay. The conditions under which the proposed scheme can show improvement are identified.
584490
Surface interpolation of meshes by geometric subdivision
Subdivision surfaces are generated by repeated approximation or interpolation from initial control meshes. In this paper, two new non-linear subdivision schemes, face based subdivision scheme and normal based subdivision scheme, are introduced for surface interpolation of triangular meshes. With a given coarse mesh more and more details will be added to the surface when the triangles have been split and refined. Because every intermediate mesh is a piecewise linear approximation to the final surface, the first type of subdivision scheme computes each new vertex as the solution to a least square fitting problem of selected old vertices and their neighboring triangles. Consequently, sharp features as well as smooth regions are generated automatically. For the second type of subdivision, the displacement for every new vertex is computed as a combination of normals at old vertices. By computing the vertex normals adaptively, the limit surface is G^1 smooth. The fairness of the interpolating surface can be improved further by using the neighboring faces. Because the new vertices by either of these two schemes depend on the local geometry, but not the vertex valences, the interpolating surface inherits the shape of the initial control mesh more fairly and naturally. Several examples are also presented to show the efficiency of the new algorithms.
5734078
A DoS-limiting network architecture
We present the design and evaluation of TVA, a network architecture that limits the impact of Denial of Service (DoS) floods from the outset. Our work builds on earlier work on capabilities in which senders obtain short-term authorizations from receivers that they stamp on their packets. We address the full range of possible attacks against communication between pairs of hosts, including spoofed packet floods, network and host bottlenecks, and router state exhaustion. We use simulation to show that attack traffic can only degrade legitimate traffic to a limited extent, significantly outperforming previously proposed DoS solutions. We use a modified Linux kernel implementation to argue that our design can run on gigabit links using only inexpensive off-the-shelf hardware. Our design is also suitable for transition into practice, providing incremental benefit for incremental deployment.
18376953
Planar point set fairing and fitting by arc splines
Abstract We fair and fit planar point sets by minimal-energy arc splines. The fairing process consists of two steps: computing the optimal tangents for curve interpolation and adjusting the point positions by smoothing the discrete curvatures. To fit the point set with minimal-energy arc curve, a simple linear algorithm is given for computing the optimal tangents. The discrete curvatures derived from the optimal tangents can be made smooth by low-pass filtering. These two linear and local algorithms are combined to generate a fair point set together with a fair G 1 arc curve within a given tolerance of the original data. The method can be used for fair shape design and measured data processing. Numerical examples are given to show the efficiency of this method.
3643118
Skeleton-driven 2D distance field metamorphosis using intrinsic shape parameters
In this article a novel algorithm is presented for 2D shape interpolation using the intrinsic shape parameters of a piecewise linear curve. The skeletons of two given shapes are computed and the smooth transformation of distance fields is driven by metamorphosis from the skeleton of the source object to that of the target one. We introduce feature graphs, linear forms of skeletons, to guide the construction of intermediate skeleton. If the topologies of the source object and the target one are different, their feature graphs will be automatically extended with equivalent topologies. Then we apply the technique of intrinsic shape parameters to the smooth transition of the extended feature graphs, which will guide the metamorphosis of the skeletons. Not only can the new approach be capable of morphing between objects with different topological genus, but also the topologies and the shapes of the intermediate objects can be controlled efficiently.
7182914
A Twin-Candidate Model of Coreference Resolution with Non-Anaphor Identification Capability
Although effective for antecedent determination, the traditional twin-candidate model can not prevent the invalid resolution of non-anaphors without additional measures. In this paper we propose a modified learning framework for the twin-candidate model. In the new framework, we make use of non-anaphors to create a special class of training instances, which leads to a classifier capable of identifying the cases of non-anaphors during resolution. In this way, the twin-candidate model itself could avoid the resolution of non-anaphors, and thus could be directly deployed to coreference resolution. The evaluation done on newswire domain shows that the twin-candidate based system with our modified framework achieves better and more reliable performance than those with other solutions.