With the increasing use of geometry scanners to create 3D models, there is a rising need for fast and robust mesh smoothing to remove inevitable noise in the measurements. While most previous work has favored diffusion-based iterative techniques for feature-preserving smoothing, we propose a radically different approach, based on robust statistics and local first-order predictors of the surface. The robustness of our local estimates allows us to derive a non-iterative feature-preserving filtering technique applicable to arbitrary "triangle soups". We demonstrate its simplicity of implementation and its efficiency, which make it an excellent solution for smoothing large, noisy, and non-manifold meshes. / Singapore-MIT Alliance (SMA)

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Recent innovations in design and construction of architectural buildings has led us to revisit the metrics for discretizing smooth freeform shapes in context with both aesthetics and fabrication. Inspired by the examples of the British Museum Court Roof in Britain and the Beijing Aquatic Centre in China, we propose solutions for generating aesthetic as well as economically viable solutions for tessellating smooth, freeform shapes. For the purpose of generating an aesthetic tessellation, we propose a simple linearized strain based metric to minimize dissimilarity amongst triangles in a local neighborhood. We do so by defining an error function that measures deformation required to map a pair of triangles onto each other. We minimize the error using a global non-linear optimization based framework. We also reduce the complexity associated with prefabricating triangulated panels for a given shape. To do so, we propose a global optimization based framework to approximate any given shape using significantly reduced numbers of unique triangles. By doing so, we leverage the economies of scale as well as simplify the process of physical placement of panels by manual labor.

Recent advances in Wireless Mesh Networks (WMNs) have overcome the drawbacks of traditional wired networks and wireless ad hoc networks. WMNs will play a leading role in the next generation of networks, and the question of how to provide smooth mobility for WMNs is the driving force behind the research. The inherent characteristics of WMNs, such as relatively static backbones and highly mobile clients, require new handoff management solutions to be designed and implemented. This thesis first presents our research work on handoff management schemes in traditional WMNs. In general, a handoff process includes two parts, the MAC layer handoff and the network layer handoff. For the MAC layer handoff, a self-configured handoff scheme with dynamic adaptation is presented. Before the mobile node starts the probe process, it configures parameters for each channel to optimize the scan process. Moreover, a fast authentication scheme to reduce authentication latency for WiFi-based mesh networks is introduced. A tunnel is introduced to forward data packets between the new access router and the original reliable access router to recover data communication before the complete authentication process is finished. To minimize the network layer handoff latency, a hybrid routing protocol for forwarding packets is proposed: this involves both the link layer routing and the network layer routing. Based on the hybrid routing protocol, both intra-domain and inter-domain handoff management have been designed to support smooth roaming in WMNs. In addition, we extend our work to Vehicular Mesh Networks (VMNs). Considering the characteristics of VMNs, a fast handoff scheme is introduced to reduce handoff latency by using a multi-hop clustering algorithm. Using this scheme, vehicle nodes are divided into different multi-hop clusters according to the relative mobility. Some vehicle nodes are selected as assistant nodes; and these assistant nodes will help the cluster head node to determine the next access router for minimizing handoff latency. Extensive simulation results demonstrate that the proposed scheme can reduce handoff latency significantly.

The Master’s thesis report describes the wireless mesh networks functions, characteristics, network management and finally different protocols with security issues and applications. Wireless Networks (WMNs) are replacing wireless Infrastructure networks in many areas because of their lower and higher flexibility. The wireless mesh networks (WMNs) provides network access for both mesh and conventional clients through mesh routers and mesh clients. Communication across the network is formed via the bridge functions. Mesh router also provides the minimal mobility and form the backbone of WMNs. Wireless mesh network has resolved the limitation of ad hoc networks which is ultimately improves the performance of Ad hoc networks. Security is a very important issue which can be resolve through proper management of network. The improvment of 802.11i security has greatly improved the network perfomance and increase the encryption and integrity security capabilities. The key points which are being addressed in this report are security issues and threats and their counter measures. Attacks which can come on diffent layers are being discussed in this survey. Security of wireless mesh network is still under consideration. Wireless mesh network are attracting more attention due to its enhanced features. Wireless mesh network topology technology is being discussed in this report. Then network management of WMNs is explained and in the concluding chapters security issues are discussed. Threats, attacks and challenges of WMNs are discussed in this survey.

In architectural and sculptural practice, the eventual goal is constructing the shapes that have been designed. Due to fabrication considerations, shapes with planar faces are in demand for these practices. In this thesis, a novel computational modeling approach to design constructible shapes is introduced. This method guarantees that the resulting shapes are planar meshes with 3-valence vertices, which can always be physically constructed using planar or developable materials such as glass, sheet metal or plywood. The method introduced is inspired by the traditional sculpture and is based on the idea of carving a mesh by using slicing planes. The process of determining the slicing planes can either be interactive or automated. A framework is developed which allows user to sculpt shapes by using the in- teractive and automated processes. The framework allows user to cut a source mesh based on its edges, faces or vertices. The user can sculpt various kinds of developable surfaces by cutting the parallel edges of the mesh. The user can also introduce in- teresting conical patterns by cutting dierent vertex, edge, face combinations of the mesh.

This dissertation describes a new version of the Generalized Finite Element Method (GFEM), which is well suited for problems set in domains with a large number of internal features (e.g. voids, inclusions, etc.), which are practically impossible to solve using the standard FEM. The main idea is to employ the mesh-based handbook functions which are solutions of boundary value problems in domains extracted from vertex patches of the employed mesh and are pasted into the global approximation by the Partition of Unity Method (PUM). It is shown that the p-version of the Generalized FEM using mesh-based handbook functions is capable of achieving very high accuracy. It is also analyzed that the effect of the main factors affecting the accuracy of the method namely: (a) The data and the buffer included in the handbook domains, and (b) The accuracy of the numerical construction of the handbook functions. The robustness of the method is illustrated by several model problems defined in domains with a large number of closely spaced voids and/or inclusions with various shapes, including the heat conduction problem defined on domains with porous media and/or a real composite material.

In architectural and sculptural practice, the eventual goal is constructing the shapes that have been designed. Due to fabrication considerations, shapes with planar faces are in demand for these practices. In this thesis, a novel computational modeling approach to design constructible shapes is introduced. This method guarantees that the resulting shapes are planar meshes with 3-valence vertices, which can always be physically constructed using planar or developable materials such as glass, sheet metal or plywood. The method introduced is inspired by the traditional sculpture and is based on the idea of carving a mesh by using slicing planes. The process of determining the slicing planes can either be interactive or automated. A framework is developed which allows user to sculpt shapes by using the in- teractive and automated processes. The framework allows user to cut a source mesh based on its edges, faces or vertices. The user can sculpt various kinds of developable surfaces by cutting the parallel edges of the mesh. The user can also introduce in- teresting conical patterns by cutting dierent vertex, edge, face combinations of the mesh.

Wimax (Worldwide Interoperability for Microwave Access) is a standard of wireless metropolitan area networks (WMAN), designed by IEEE 802.16 standards group. The coverage of Wimax is wide, so it is suited for developing in large networks and provides more steady, high-speed, and secure data transmission for fixed and mobile subscribers. As the result, Wimax is designed for solving last mile problem because of the bandwidth is limit and the expensive building cost in the traditional networks. IEEE 802.16 (Wimax) defines two modes of data communication topology: PMP (Point-to-multipoint) mode and Mesh mode. In Mesh mode, the data can route through another subscriber station (SS), so it not only improves coverage range but also raises the throughput. Although IEEE 802.16 defined a secure sub layer in the MAC (Media Access Control) layer to provide privacy by encrypting connections between base station (BS) and subscriber station (SS), but it still face many security problems. In the mesh mode, it is not like PMP mode that the traffic is only between BS and SS, the traffic sometime will pass through another SS, for this reason, it is prone to bring many problems, such as shared secret key exposing, man-in-the-middle attack, eavesdropping threat¡Ketc. On the relay node (we termed sponsor node here), it also involved more unnecessary loads of encryption and decryption. In this thesis, we focus on the MAC layer , and we propose some schemes to modify the present of PKM and the traffic encryption key used for transmitting data, and we will show that these schemes can achieve better security than previous ones, also achieve efficient in data transmission.

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