ppxscal/embedding_network huggingface dataset:
Boundary treatments in non-equilibrium Green's function (NEGF) methods for quantum transport in nano-MOSFETs
Authors: Haiyan Jiang, Sihong Shao, Wei Cai, Pingwen Zhang
Venue: Journal of Computational Physics (2008)

Non-equilibrium Green's function (NEGF) is a general method for modeling non-equilibrium quantum transport in open mesoscopic systems with many body scattering effects. In this paper, we present a unified treatment of quantum device boundaries in the framework of NEGF with both finite difference and finite element discretizations. Boundary treatments for both types of numerical methods, and the resulting self-energy @S for the NEGF formulism, representing the dissipative effects of device contacts on the transport, are derived using auxiliary Green's functions for the exterior of the quantum devices. Numerical results with both discretization schemes for an one-dimensional nano-device and a 29nm double gated MOSFET are provided to demonstrate the accuracy and flexibility of the proposed boundary treatments.
Video frame rate up conversion under inconsistent camera motion
Authors: Jinsong Wang, Nilesh Patel, William Grosky, Farshad Fotouhi
Venue: Multimedia Tools and Applications (2008)

In this paper, we address the problem of video frame rate up-conversion (FRC) in the compressed domain. FRC is often recognized as video temporal interpolation. This problem is very challenging when targeted for video sequences with inconsistent camera and object motion, such as sports videos. A novel compressed domain motion compensation scheme is presented and applied in this paper, aiming at up-sampling frame rates in sports videos. MPEG-2 encoded motion vectors (MVs) are utilized as inputs in the proposed algorithm. The decoded MVs undergo a cumulative spatiotemporal interpolation. An iterative rejection scheme based on the dense motion vector field (MVF) and the generalized affine motion model is exploited to detect global camera motion. Subsequently, the foreground object separation is performed by additionally examining the temporal consistency of the output of iterative rejections. This consistency check process helps coalesce the resulting foreground blocks and weed out the unqualified blocks. Finally, different compensation strategies for the camera and object motions are applied to interpolate the new frames. Illustrative examples are provided to demonstrate the efficacy of the proposed approach. Experimental results are compared with the popular block and non-block based frame interpolation approaches.
Constructivism, virtual reality and tools to support design
Authors: Cara Winterbottom, Edwin Blake
Venue: Proceedings of the 7th ACM conference on Designing interactive systems (2008)

This paper describes a process for creating a design tool, which is based in constructivism. The process is described for the creation of a tool to help novices in designing virtual environment interactions, however it can be generalized to other design domains. The process consists of four steps: first constructivist values of atomic simplicity, multiplicity, exploration, control and reflection are distilled. Next, expert practices are researched and reframed in terms of the constructivist values. Thirdly, novice processes are examined and understood in constructivist terms. Lastly, prototypes are created and shown to target users. These steps are iterated until the designed tool is satisfactory.
Coordinated traversal: (t+1)-round Byzantine agreement in polynomial time
Authors: Y. Moses, O. Waarts
Venue: Proceedings of the 29th Annual Symposium on Foundations of Computer Science (1988)

The problem of efficiently performing Byzantine agreement in t+1 rounds in the face of arbitrarily malicious failures is treated. A communication-efficient polynomial-time protocol is presented for n>8t. The protocol is an early stopping protocol, halting in min(t+1, f+2) rounds in the worst case, where f is the number of processors that fail during the run. This is provably optimal. The protocol is based on a careful combination of early stopping, fault masking, and a technique called coordinated traversal. The combination of the three provides a powerful method for restricting the damage that a faulty processor, however malicious, can do. One of the byproducts of this protocol is a polynomial-time (t+1)-round protocol for the Byzantine firing squad problem.
Experimental Evaluation and Characterization of Long-Distance 802.11g Links
Authors: Hesham El-Sayed, Sherali Zeadally, Mohamed Boulmalf
Venue: Proceedings of the Seventh International Conference on Networking (2008)

The use of 802.11 long-distance links is a cost-effective means of providing wireless connectivity to rural areas. Although deployments in such settings are increasing, there are few empirical results reported on the performance of 802.11 over long distances. An empirical evaluation of 802.11 performance over long distances is a non-trivial task since it involves several variables such as the network topology, tower heights, antenna types used and their orientations, and radio transmit powers. The task is further complicated by the presence of network performance constraints, and the inter-dependence among the variables. In this paper we present an empirical performance study of long-distance 802.11g links using metrics such as signal strength, free space loss, jitter and round-trip time. In addition, we also develop a theoretical model of the wireless link to validate our experimental measurements.
A Fast and Robust Approach to Liver Nodule Detection in MR Images
Authors: Dongjiao Lu, Jue Zhang, Xiaoying Wang, Jing Fang
Venue: Proceedings of the 2007 Frontiers in the Convergence of Bioscience and Information Technologies (2007)

Liver cancer has a high mortality rate in Asia, and is characterized by dysplastic nodules in early stages. An important step in the early detection of this disease is accurate detection of these nodules, which can be dysplastic or regenerative.
Can software reliability outperform hardware reliability on high performance interconnects?: a case study with MPI over infiniband
Authors: Matthew J. Koop, Rahul Kumar, Dhabaleswar K. Panda
Venue: Proceedings of the 22nd annual international conference on Supercomputing (2008)

An important part of modern supercomputing platforms is the network interconnect. As the number of computing nodes in clusters have increased, the role of the interconnect has become more important. Modern interconnects, such as InfiniBand, Quadrics, and Myrinet have become popular due to their low latency and increased performance over traditional Ethernet. As these interconnects become more widely used and clusters continue to scale, design choices such as where data reliability should be provided are an important issue. In this work we address the issue of network reliability design using InfiniBand as a case study. Unlike other high-performance interconnects, InfiniBand exposes both reliable and unreliable APIs. As part of our study we implement the Message Passing Interface (MPI) over the Unreliable Connection (UC) transport and compare with the Reliable Connection (RC) and Unreliable Datagram (UD) transports for MPI. We detail the costs of reliability for different message patterns and show that providing reliability in software instead of hardware can increase performance up to 25% in a molecular dynamics application (NAMD) on a 512-core InfiniBand cluster.
Building a database on S3
Authors: Matthias Brantner, Daniela Florescu, David Graf, Donald Kossmann, Tim Kraska
Venue: Proceedings of the 2008 ACM SIGMOD international conference on Management of data (2008)

There has been a great deal of hype about Amazon's simple storage service (S3). S3 provides infinite scalability and high availability at low cost. Currently, S3 is used mostly to store multi-media documents (videos, photos, audio) which are shared by a community of people and rarely updated. The purpose of this paper is to demonstrate the opportunities and limitations of using S3 as a storage system for general-purpose database applications which involve small objects and frequent updates. Read, write, and commit protocols are presented. Furthermore, the cost ($), performance, and consistency properties of such a storage system are studied.
Formal models of coherence and legal epistemology
Authors: Amalia Amaya
Venue: Artificial Intelligence and Law (2007)

This paper argues that formal models of coherence are useful for constructing a legal epistemology. Two main formal approaches to coherence are examined: coherence-based models of belief revision and the theory of coherence as constraint satisfaction. It is shown that these approaches shed light on central aspects of a coherentist legal epistemology, such as the concept of coherence, the dynamics of coherentist justification in law, and the mechanisms whereby coherence may be built in the course of legal decision-making.
An extended GRAI model for enterprise process diagnosis
Authors: X. Wen, X. Xu, G. Wang, Y. Gong, R. Lv
Venue: International Journal of Computer Integrated Manufacturing (2007)

With GRAI GRID and GRAI NET offered, GRAI method has great advantage over other modelling methods in decision-making of enterprise manufacturing systems. However, it has a flaw in description ability for enterprises, which effects its decision-making ability in other fields. To solve more enterprise problems, GRAI method needs to be extended. In this paper an extended GRAI model for enterprise process diagnosis is presented. The diagnosis model includes an extended GRAI grid view and an extended GRAI net view used to aid the diagnosis of certain aspects of an enterprise, such as business process, organization, resource and information. A mapping mechanism among views and some rules of model maintenance are also put forward. Based on the model, a systematic diagnosis procedure and types of problems that can be diagnosed are introduced. Finally, an instance of enterprise process diagnosis is mentioned in detail.
Upper bound limit and shakedown analysis of shells using the exact Ilyushin yield surface
Authors: Thanh Ngc Tran, R. Kreiíig, Duc Khôi Vu, Manfred Staat
Venue: Computers and Structures (2008)

This paper concerns the development of a kinematic formulation for the finite element limit and shakedown analysis of shells. The technique is based upon an upper bound approach using the re-parameterized exact Ilyushin yield surface and a nonlinear optimization procedure. The solution of the problem is obtained by discretizing the shell into finite elements. Numerical examples are presented to show the validity of the present method.
A new FIR filter for state estimation and its application
Authors: Pyung-Soo Kim, Myung-Eui Lee
Venue: Journal of Computer Science and Technology (2007)

This paper proposes a new FIR (finite impulse response) filter under a least squares criterion using a forgetting factor. The proposed FIR filter does not require information of the noise covariances as well as the initial state, and has some inherent properties such as time-invariance, unbiasedness and deadbeat. The proposed FIR filter is represented in a batch form and then a recursive form as an alternative form. From discussions about the choice of a forgetting factor and a window length, it is shown that they can be considered as useful parameters to make the estimation performance of the proposed FIR filter as good as possible. It is shown that the proposed FIR filter can outperform the existing FIR filter with incorrect noise covariances via computer simulations. Finally, as a useful application, an image sequence stabilization problem is considered. Through this application, the FIR filtering based approach is shown to be superior to the Kalman filtering based approach.
Preface to the special issue: Isomorphisms of types and invertibility of lambda terms
Authors: Ralph Matthes, Sergei Soloviev
Venue: Mathematical Structures in Computer Science (2008)

Isomorphisms of types are computational witnesses of logical equivalence with additional properties. The types/formulas A and B are isomorphic if there are functions (in a certain formalism) f : A → B and g : B → A such that g ○ f and f ○ g are equal in a certain sense to the identity on A and B, respectively. Typical such formalisms are extensions of simply typed λ-calculus, with βη-convertibility as equality relation. Another view of a pair of functions f : A → B and g : B → A (besides establishing the logical equivalence of A and B) is that f is invertible with left-inverse g, and it is then natural to relax the above symmetric condition to just g ○ f being equal to the identity on A. In this situation, A is called a retract of B, which is thus a natural generalisation of the notion of an isomorphism, while both these notions are refinements of the concept of logical equivalence in operational terms, that is, in terms of computable functions.
Simultaneous optimization of the material properties and the topology of functionally graded structures
Authors: Qi Xia, Michael Yu Wang
Venue: Computer-Aided Design (2008)

A level set based method is proposed for the simultaneous optimization of the material properties and the topology of functionally graded structures. The objective of the present study is to determine the optimal material properties (via the material volume fractions) and the structural topology to maximize the performance of the structure in a given application. In the proposed method, the volume fraction and the structural boundary are considered as the design variables, with the former being discretized as a scalar field and the latter being implicitly represented by the level set method. To perform simultaneous optimization, the two design variables are integrated into a common objective functional. Sensitivity analysis is conducted to obtain the descent directions. The optimization process is then expressed as the solution to a coupled Hamilton-Jacobi equation and diffusion partial differential equation. Numerical results are provided for the problem of mean compliance optimization in two dimensions.
Model-driven design and implementation of discrete event control for a machine tool control system
Authors: Y. Liu, W. Li, K. Yamazaki, M. Fujishima
Venue: International Journal of Computer Integrated Manufacturing (2007)

Design and implementation of discrete event control for machine tool control system is extremely complicated. In current industrial practice, designers tend to derive implementations from a rough system design in terms of system specification analysis. Such an implementation-based method leads to ad hoc system design and implementation, with system performance that relies highly on the designers' experiences. Usually a long 'cycle and debug' stage is needed to fix errors after a prototype system has been built. In addition, it is always difficult to build a new system by modifying an existing one when the specification is changed. In this paper, the authors propose a model-driven method to enhance the design and implementation of discrete event control for a machine tool control system. Based on the system specification, an executable model is first built. This model is then evaluated by simulation to eliminate the design errors before implementation. Finally for system implementation, a separate process engine with operation rules is obtained from the model. A key module of machine tool control system is used to illustrate the proposed method.
Matchings in hypergraphs of large minimum degree
Authors: Daniela Kühn, Deryk Osthus
Venue: Journal of Graph Theory (2006)

It is well known that every bipartite graph with vertex classes of size n whose minimum degree is at least n-2 contains a perfect matching. We prove an analog of this result for hypergraphs. We also prove several related results that guarantee the existence of almost perfect matchings in r-uniform hypergraphs of large minimum degree. Our bounds on the minimum degree are essentially best possible. &copy; 2005 Wiley Periodicals, Inc. J Graph Theory 51: 269&ndash;280, 2006
On control of stochastic sensitivity
Authors: L. B. Ryashko, I. A. Bashkirtseva
Venue: Automation and Remote Control (2008)

Consideration was given to generation of the desired probabilistic characteristics of the attractors of the nonlinear stochastic control systems. In the case of small random perturbations, the scatter of trajectories in the neighborhood of stable equilibrium is describable in terms of the stochastic sensitivity matrix. Problem was posed of generating the desired stochastic sensitivity matrix. The corresponding notions of reachability and full controllability were examined. A criterion for full controllability was obtained, and a constructive description of the reachability set was given. Efficiency of the proposed constructions was demonstrated by way of example of control of the stationary distribution of the random states of the perturbed stochastic Van der Pol's equation.
Adaptive Compression of Graph Structured Text
Authors: John Gilbert, David M. Abrahamson
Venue: Proceedings of the Data Compression Conference (2008)

In this paper we introduce an adaptive technique for compressing small quantities of text which are organized as a rooted directed graph. We impose a constraint on the technique such that data encountered during a traversal of any valid path through the graph must be recoverable without requiring the expansion of data that is not on the path in question. The technique we present determines the set of nodes y which are guaranteed to be encountered before reaching node x while traversing any valid path in the graph, and uses them as a basis for conditioning an LZW dictionary for the compression/expansion of the data in x. Initial results show that our improved LZW technique reduces the compressed text size by approximately 20% more than regular LZW, and requires only minor modifications to the standard LZW decompression routine.
Symmetric replication for efficient flooding in DHTs
Authors: Salma Ktari, Mathieu Zoubert, Artur Hecker, Houda Labiod
Venue: Proceedings of the 9th ACM international symposium on Mobile ad hoc networking and computing (2008)

To support complex queries and broadcast in DHTs, we propose an algorithm for an effective flooding that we implement and compare in a Chord DHT. We use flooding and replication that exploit structural constraints to achieve lower overhead and higher reliability.
Switching visual control based on epipoles for mobile robots
Authors: G. López-Nicolás, C. Sagüés, J. J. Guerrero, D. Kragic, P. Jensfelt
Venue: Robotics and Autonomous Systems (2008)

In this paper, we present a visual control approach consisting in a switching control scheme based on the epipolar geometry. The method facilitates a classical teach-by-showing approach where a reference image is used to control the robot to the desired pose (position and orientation). As a result of our proposal a mobile robot carries out a smooth trajectory towards the target and the epipolar geometry model is used through the whole motion. The control scheme developed considers the motion constraints of the mobile platform in a framework based on the epipolar geometry that does not rely on artificial markers or specific models of the environment. The proposed method is designed in order to cope with the degenerate estimation case of the epipolar geometry with short baseline. Experimental evaluation has been performed in realistic indoor and outdoor settings.
Spectral mesh deformation
Authors: Guodong Rong, Yan Cao, Xiaohu Guo
Venue: The Visual Computer: International Journal of Computer Graphics (2008)

In this paper, we present a novel spectral method for mesh deformation based on manifold harmonics transform. The eigenfunctions of the Laplace&#x2013;Beltrami operator give orthogonal bases for parameterizing the space of functions defined on the surfaces. The geometry and motion of the original irregular meshes can be compactly encoded using the low-frequency spectrum of the manifold harmonics. Using the spectral method, the size of the linear deformation system can be significantly reduced to achieve interactive computational speed for manipulating large triangle meshes. Our experimental results demonstrate that only a small spectrum is needed to achieve undistinguishable deformations for large triangle meshes. The spectral mesh deformation approach shows great performance improvement on computational speed over its spatial counterparts.
Social network analysis: a new approach for business process reengineering
Authors: Jianfeng Li, Yan Chen
Venue: Proceedings of the 10th WSEAS International Conference on APPLIED MATHEMATICS (2006)

In today's competitive environment, business process reengineering has a great role in improving operational efficiency for most organizations. This paper bases on social network analysis (SNA) as a new approach to work over configurable efficiency for business process reengineering without respect to other factors. Organization is regard as the network where units or actor are as nodes and relations are as the connectors between nodes. According to some measuring indexes of SNA, characteristics of each actor's exchanging activities affected by the structure are shown obviously. It's favourable to reveal the myth of connection and redesign the business process in the organization.
Metasearch Engines and Information Retrieval: Computational Complexity of Ranking Multiple Search Results
Authors: Robert Goldberg, Isak Taksa, Amanda Spink
Venue: Proceedings of the Fifth International Conference on Information Technology: New Generations (2008)

This paper analyzes the computational complexity of finding relevant documents on the Web. Given a search query that has n significant terms, relevant documents retrieved by search engines will contain at least a number k of the significant terms. The threshold k chosen will depend on the collection of documents and is determined experimentally upon formation of the collection. Algorithms are then provided to compute a similarity ranking. The fundamental analysis is based on combinatorial theory and theorems providing bounds on the runtime complexity of the algorithms are proven.
SafeResynth: A new technique for physical synthesis
Authors: Kai-hui Chang, Igor L. Markov, Valeria Bertacco
Venue: Integration, the VLSI Journal (2008)

Physical synthesis is a relatively young field in Electronic Design Automation. Many published optimizations for physical synthesis end up hurting the quality of the final design, often because they neglect important physical aspects of the layout, such as long wires or routing congestion. Our work defines and explores the concept of physical safeness and evaluates empirically its impact on route length, via count and timing. In addition, we propose a new physically safe and logically sound optimization, called SafeResynth, which provides immediately measurable improvements without altering the design's functionality. SafeResynth can enhance circuit timing without detrimental effects on route length and congestion. We achieve these improvements by performing a series of netlist transformations and re-placements that are individually evaluated for logical soundness (that is, they do not alter the logic functionality) and for physical safeness. When used alone, SafeResynth improves circuit delay of IWLS'05 benchmarks by 11% on average after routing, while increasing route length by less than 0.2%. Since transistors are not affected by SafeResynth, it can also be applied to post-silicon debugging, where only metal fixes are possible.