9865654
A reversible data hiding approach to mesh authentication
This paper proposes a reversible data hiding method to authenticate 3D meshes by modulating the distances from the mesh faces to the mesh centroid to embed a fragile watermark. It keeps the modulation information in the watermarked mesh so that the reversibility of the embedding process is achieved. Since the embedded watermark is sensitive to geometrical and topological processing, unauthorized modifications on the watermarked mesh can be therefore detected by retrieving and comparing the embedded watermark with the original one. Furthermore, as long as the watermarked mesh is intact, the original mesh can be recovered using some priori knowledge.
14728640
Public Authentication of 3D Mesh Models
In this paper, a public-key scheme is proposed to authenticate 3D mesh models. It is well known that digital signature schemes can be used for data authentication by generating a separate signature and appending it to the file. Another way is divide the original data into two parts: the content to be authenticated and the cover content. In the embedding process, the signature of the first part is generated and imperceptibly embedded within the cover content to form the signed content. In the authentication process, a new hash value is produced from the signed content and compared with the value decrypted from the retrieved signature for tamper detection. Before we implement such a scheme on polygonal meshes, mesh partitioning technique is used to divide them into patches with a fixed amount of vertices. For each patch, a corresponding signature is generated to replace the least significant bits of vertex coordinates within it so that the tamper can be localized. The experimental results have shown the promising results
16314153
A New Fragile Mesh Watermarking Algorithm for Authentication
In this paper, we propose a new fragile watermarking algorithm based on the global characteristics of the mesh geometry to authenticate 3D mesh models. In our method, a sequence of data bits is adaptively embedded into the mesh model by properly adjusting the vertex positions, and the bit information can be blindly extracted from the watermarked mesh model using a key. The embedding process is adaptive to the mesh model so that the watermarked mesh is perceptually indistinguishable from the original. We show that the embedded watermark is invariant to affine transformation but sensitive to other operations. Besides, the embedding strength is adjustable and can be controlled to a certain extent that even a trivial tampering with the watermarked mesh would lead the watermark signal to change. Therefore, unauthorized modifications of the mesh models can be detected and estimated.
13992284
CPU scheduling for statistically-assured real-time performance and improved energy efficiency
We present a CPU scheduling algorithm, called Energy-efficient Utility Accrual Algorithm (or EUA), for battery-powered, embedded real-time systems. We consider an embedded software application model where repeatedly occurring application activities are subject to deadline constraints specified using step time/utility functions. For battery-powered embedded systems, system-level energy consumption is also a primary concern. We consider CPU scheduling that (1) provides assurances on individual and collective application timeliness behaviors and (2) maximizes system-level timeliness and energy efficiency. Since the scheduling problem is intractable, EUA heuristically computes CPU schedules with a polynomial-time cost. Several properties of EUA are analytically established, including timeliness optimality during under-load situations and statistical assurances on timeliness behavior. Further, our simulation results confirm EUA's superior performance.
9516398
The CenSSIS image database
The CenSSIS image database is a scientific database that enables effective data management and collaboration to accelerate fundamental research. This paper describes the design and use of a state-of-the-art relational image database management system, accessible through a standard Web-browser interface. The application utilizes a robust security architecture and is designed for efficient data submission. Our database query engine provides complex query capabilities to facilitate fast and efficient data retrieval. The system offers a highly extensible metadata schema, with the option of storing data within a hierarchical format.
5941019
Utility accrual scheduling under joint utility and resource constraints
We extend time/utility functions and utility accrual model with the concept of joint utility functions (or JUFs) that allow an activity's utility to be described as a function of the completion times of other activities and their progress. We also specify the concept of progressive utility that generalizes the previously studied imprecise computational model, by describing an activity's utility as a function of its progress. Given such an extended utility accrual model, we consider the scheduling criterion of maximizing the weighted sum of completion time, progressive, and joint utilities. We present an algorithm called the combined utility accrual algorithm (or CUA)for this criterion. Experimental measurements with an implementation of CUA on a POSIX RTOS illustrate the effectiveness of JUFs in a class of applications of interest to us
7266719
Two processor scheduling with real release times and deadlines
In a hard real-time system, critical tasks are subject to timing constraints such as release times and deadlines. All timing constraints must be satisfied when tasks are executed. Nevertheless, given a set of tasks, finding a feasible schedule which satisfies all timing constraints is NP-complete even on one processor.In this paper, we study the following special non-pre-emptive two processor scheduling problem: Given a set of UET (Unit Execution Time) tasks with arbitrary precedence constraints, individual real release times and deadlines, find a feasible schedule on two identical processors whenever one exists. The complexity status of this problem has been open for a long time. we propose the first polynomial algorithm for this problem. Our algorithm is underpinned by the key consistency notion: successor-tree-consistency. The time complexity of our algorithm is O(n4), where n is the number of tasks.
31035436
Contractible Elements in Graphs and Matroids
Let G be a simple 3-connected graph with at least five vertices. Tutte [13] showed that G has at least one contractible edge. Thomassen [11] gave a simple proof of this fact and showed that contractible edges have many applications. In this paper, we show that there are at most $\frac{|V(G)|}{5}$ vertices that are not incident to contractible edges in a 3-connected graph G. This bound is best-possible. We also show that if a vertex v is not incident to any contractible edge in G, then v has at least four neighbours having degree three, and each such neighbour is incident to exactly two contractible edges. We give short proofs of several results on contractible edges in 3-connected graphs as well. We also study the contractible elements for k-connected matroids. We partially solve an open problem for regular matroids.