ppxscal/embedding_network huggingface dataset:
Divisibility of countable metric spaces
Authors: Christian Delhommé, Claude Laflamme, Maurice Pouzet, Norbert Sauer
Venue: European Journal of Combinatorics (2007)

Prompted by a recent question of Hjorth [G. Hjorth, An oscillation theorem for groups of isometries, manuscript] as to whether a bounded Urysohn space is indivisible, that is to say has the property that any partition into finitely many pieces has one piece which contains an isometric copy of the space, we answer this question and more generally investigate partitions of countable metric spaces. We show that an indivisible metric space must be bounded and totally Cantor disconnected, which implies in particular that every Urysohn space U"V with V containing some dense initial segment of R"+ is divisible. On the other hand we also show that one can remove ''large'' pieces from a bounded Urysohn space with the remainder still inducing a copy of this space, providing a certain ''measure'' of the indivisibility. Associated with every totally Cantor disconnected space is an ultrametric space, and we go on to characterize the countable ultrametric spaces which are homogeneous and indivisible.
Proceedings. Ninth IEEE International High-Level Design Validation and Test Workshop (IEEE Cat. No.04EX940)
Venue: Proceedings of the High-Level Design Validation and Test Workshop, 2004. Ninth IEEE International (2004)

The following topics are dealt with: formal verification; formal specification; processor-oriented validation; decision diagram; validation pattern generation; behavioral modeling; fault coverage analysis; SAT solving; network architecture validation; high-level validation. The ACM Portal is published by the Association for Computing Machinery. Copyright © 2010 ACM, Inc. Terms of Usage Privacy Policy Code of Ethics Contact Us Useful downloads: Adobe Acrobat QuickTime Windows Media Player Real Player
A Novel Medical Image Segmentation Method using Dynamic Programming
Authors: Yan Zhang, Bogdan J. Matuszewski, Lik-Kwan Shark
Venue: Proceedings of the International Conference on Medical Information Visualisation - BioMedical Visualisation (2007)

A novel method is proposed to segment objects in medical images whose boundaries can be described as closed curves. Based on an image with the enhanced boundary of an object of interest, the segmentation method consists of three key steps, namely, the polar transformation, dynamic programming and curve fitting. A 3D object in volumetric data can be segmented on a slice-by-slice basis by only specifying one point inside the 3D object of interest as the pole for the polar transformation. The method is also shown to be able to segment objects with very weak boundaries.
Illumination and motion-based video enhancement for night surveillance
Authors: Jing Li, S. Z. Li, Quan Pan, Tao Yang
Venue: Proceedings of the 14th International Conference on Computer Communications and Networks (2005)

This work presents a context enhancement method of low illumination video for night surveillance. A unique characteristic of the algorithm is its ability to extract and maintenance the meaningful information like highlight area or moving objects with low contrast in the enhanced image, meanwhile recover the surrounding scene information by fusing the daytime background image. A main challenge comes from the extraction of meaningful area in the night video sequence. To address this problem, a novel bidirectional extraction approach is presented. In evaluation experiments with real data, the notable information of the night video is extracted successfully and the background scene is fused smoothly with the night images to show enhanced surveillance video for observers.
Colyseus: a distributed architecture for online multiplayer games
Authors: Ashwin Bharambe, Jeffrey Pang, Srinivasan Seshan
Venue: Proceedings of the 3rd conference on Networked Systems Design & Implementation - Volume 3 (2006)

This paper presents the design, implementation, and evaluation of Colyseus, a distributed architecture for interactive multiplayer games. Colyseus takes advantage of a game's tolerance for weakly consistent state and predictable workload to meet the tight latency constraints of game-play and maintain scalable communication costs. In addition, it provides a rich distributed query interface and effective prefetching subsystem to help locate and replicate objects before they are accessed at a node. We have implemented Colyseus and modified Quake II, a popular first person shooter game, to use it. Our measurements of Quake II and our own Colyseus-based game with hundreds of players shows that Colyseus effectively distributes game traffic across the participating nodes, allowing Colyseus to support low-latency game-play for an order of magnitude more players than existing single server designs, with similar per-node bandwidth costs.
Camera Sensor Model for Visual SLAM
Authors: Jing Wu, Hong Zhang
Venue: Proceedings of the Fourth Canadian Conference on Computer and Robot Vision (2007)

In this paper, we present a technique for the construction of a camera sensor model for visual SLAM. The proposed method is an extension of the general camera calibration procedure and requires the camera to observe a planar checkerboard pattern shown at different orientations. By iteratively placing the pattern at different distances from the camera, we can find a relationship between the measurement noise covariance matrix and the range. We conclude that the error distribution of a camera sensor follows a Gaussian distribution, based on the Geary's test, and the magnitude of the error variance is linearly related to the range between the camera and the features being observed. Our sensor model can potentially benefit visual SLAM algorithms by varying its measurement noise covariance matrix with range.
Evaluation of a Local Adaptive Protocol for Distributed Discrete Event Simulation
Authors: Donald O. Hamnes, Anand Tripathi
Venue: Proceedings of the 1994 International Conference on Parallel Processing - Volume 03 (1994)

The performance of a local adaptive protocol for distributed discrete event simulation is evaluated. This protocol allows each process to adapt at runtime to its environment on a per channel basis with the possible range of behavior varying from conservative to optimistic. This evaluation includes a comparison of the performance of the algorithm with that of both a conservative and an optimistic protocol, as well as, an examination of a number of unique characteristics of the algorithm. Results from simulations using a network of workstations on a closed queueing system are presented. The results demonstrate the importance of various protocol features and show that it performs better than either the conservative or optimistic protocols in certain simulations.
The workspace model: dynamic distribution of interactive systems
Authors: William Greg Phillips
Venue:  (2006)

This thesis presents an architectural model for synchronous groupware called the Workspace Model, which provides a clean separation of conceptual structure from distributed implementation. The model includes a formally-defined, distribution transparent, conceptual level architectural model with appropriate abstractions for the development of groupware; a formally-defined implementation level architectural model that exposes the distributed system issues abstracted at the conceptual level; a formal relation between the two levels that allows a range of implementations to be automatically computed for any conceptual level architecture; and an explicit representation of runtime change. We argue that this combination of properties allows the model to satisfy needs arising from three communities: end-users, application programmers, and toolkit developers. End users require that their groupware systems support fluid collaboration, perform efficiently, and behave in a predictable manner. Application programmers need an environment that is appropriately expressive and that doesn't require them to commit prematurely to a distributed implementation. Toolkit implementors need a model that is formally represented, that provides a range of distributed implementations, that supports efficient incremental refinement of conceptual architectures to distributed implementations. The Model has been designed such that all syntactically correct conceptual level architectures can be refined to fully refined architectures by a finite computation. A proof sketch of this key property is offered. The Workspace Model has been implemented in a toolkit and runtime system called fiia, which demonstrates that the model is both practically implementable and usable for the creation of groupware programs. The fiia programming model and the implementation of fiia itself are presented.
Automatic syllabus classification
Authors: Xiaoyan Yu, Manas Tungare, Weiguo Fan, Manuel Perez-Quinones, Edward A. Fox, William Cameron, GuoFang Teng, Lillian Cassel
Venue: Proceedings of the 7th ACM/IEEE-CS joint conference on Digital libraries (2007)

Syllabi are important educational resources. However, searching for a syllabus on the Web using a generic search engine is an error-prone process and often yields too many non-relevant links. In this paper, we present a syllabus classifier to filter noise out from search results. We discuss various steps in the classification process, including class definition, training data preparation, feature selection, and classifier building using SVM and Naïve Bayes. Empirical results indicate that the best version of our method achieves a high classification accuracy, i.e., an F1 value of 83% on average.
Structured Approach to Property Specification and Verification of HW IP
Authors: Lyes Benalycherif, Anthony McIsaac, Neil Dunlop
Venue: Proceedings of the 18th IEEE/IFIP International Workshop on Rapid System Prototyping (2007)

Formal property specification and model checking are increasingly deployed in the HW design industry, thanks to the emergence of standard property specification languages and major advances in the maturity of model checking tools. Moderately sized HW IP is now within the capacity of such tools. Complete formal verification of such IP requires not only efficient algorithms, but also a systematic approach to specifying the properties of common classes of designs. This paper addresses the methodological aspects of such an approach in an industrial setting, the Random Number Generator IP. The PSL implementation and checking considerations are dealt with including the randomness preservation property which can not be tackled by the usual specification and verification methods.
The design of pedagogical agent for distance virtual experiment
Authors: Huan-Wen Tzeng
Venue: Proceedings of the Frontiers in Education Conference, 2001. 31st Annual - Volume 02 (2001)

Experimental learning about electric-machinery is high risk and time-consuming, students do not always enjoy the laboratory, the teacher also needs to pay full attention to all students and equipment, besides it is hard to provide enough machine sets and space for learning. So it is our motivation to design a virtual laboratory for the teaching of electric-machinery experiment by Internet under the more real environment without concern about danger or limitations. It is taught by an experienced teacher using a pedagogical agent which is the most important key factor. Taking the above features into consideration, an interactive virtual laboratory based on an expert system has been designed and implemented to improve the learning, operation and control in electric-machinery experiments. The system set up is a highly intelligent and interactive mechanism. Through the system, students could have a more complete environment for distance learning.
Cryptography on a Speck of Dust
Authors: Jens-Peter Kaps, Gunnar Gaubatz, Berk Sunar
Venue: Computer (2007)

As tiny wireless sensors and RFID tags become ubiquitous, they impact privacy, trust, and control. Protecting data on these devices requires new algorithms suitable for ultralow-power implementations.
Head gestures for perceptual interfaces: The role of context in improving recognition
Authors: Louis-Philippe Morency, Candace Sidner, Christopher Lee, Trevor Darrell
Venue: Artificial Intelligence (2007)

Head pose and gesture offer several conversational grounding cues and are used extensively in face-to-face interaction among people. To accurately recognize visual feedback, humans often use contextual knowledge from previous and current events to anticipate when feedback is most likely to occur. In this paper we describe how contextual information can be used to predict visual feedback and improve recognition of head gestures in human-computer interfaces. Lexical, prosodic, timing, and gesture features can be used to predict a user's visual feedback during conversational dialog with a robotic or virtual agent. In non-conversational interfaces, context features based on user-interface system events can improve detection of head gestures for dialog box confirmation or document browsing. Our user study with prototype gesture-based components indicate quantitative and qualitative benefits of gesture-based confirmation over conventional alternatives. Using a discriminative approach to contextual prediction and multi-modal integration, performance of head gesture detection was improved with context features even when the topic of the test set was significantly different than the training set.
Key management in an encrypting file system
Authors: Matt Blaze
Venue: Proceedings of the USENIX Summer 1994 Technical Conference on USENIX Summer 1994 Technical Conference - Volume 1 (1994)

As distributed computing systems grow in size, complexity and variety of application, the problem of protecting sensitive data from unauthorized disclosure and tampering becomes increasingly important. Cryptographic techniques can play an important role in protecting communication links and file data, since access to data can be limited to those who hold the proper key. In the case of file data, however, the routine use of encryption facilities often places the organizational requirements of information security in opposition to those of information management. Since strong encryption implies that only the holders of the cryptographic key have access to the cleartext data, an organization may be denied the use of its own critical business records if the key used to encrypt these records becomes unavailable (e.g., through the accidental death of the key holder). This paper describes a system, based on cryptographic "smartcards," for the temporary "escrow" of file encryption keys for critical files in a cryptographic file system. Unlike conventional escrow schemes, this system is bilaterally auditable, in that the holder of an escrowed key can verify that, in fact, he or she holds the key to a particular directory and the owner of the key can verify, when the escrow period is ended, that the escrow agent has neither used the key nor can use it in the future. We describe a new algorithm, based on the DES cipher, for the on-line encryption of file data in a secure and efficient manner that is suitable for use in a smartcard.
An architecture for internet data transfer
Authors: Niraj Tolia, Michael Kaminsky, David G. Andersen, Swapnil Patil
Venue: Proceedings of the 3rd conference on Networked Systems Design & Implementation - Volume 3 (2006)

This paper presents the design and implementation of DOT, a flexible architecture for data transfer. This architecture separates content negotiation from the data transfer itself. Applications determine what data they need to send and then use a new transfer service to send it. This transfer service acts as a common interface between applications and the lower-level network layers, facilitating innovation both above and below. The transfer service frees developers from re-inventing transfer mechanisms in each new application. New transfer mechanisms, in turn, can be easily deployed without modifying existing applications. We discuss the benefits that arise from separating data transfer into a service and the challenges this service must overcome. The paper then examines the implementation of DOT and its plugin framework for creating new data transfer mechanisms. A set of microbenchmarks shows that the DOT prototype performs well, and that the overhead it imposes is unnoticeable in the wide-area. End-to-end experiments using more complex configurations demonstrate DOT's ability to implement effective, new data delivery mechanisms underneath existing services. Finally, we evaluate a production mail server modified to use DOT using trace data gathered from a live email server. Converting the mail server required only 184 lines-of-code changes to the server, and the resulting system reduces the bandwidth needed to send email by up to 20%.
Performance analysis for direction finding in non-Gaussian noise
Authors: B. M. Sadler
Venue: Proceedings of the Acoustics, Speech, and Signal Processing, 1999. on 1999 IEEE International Conference - Volume 05 (1999)

We consider narrowband angle of arrival estimation in non-Gaussian (NG) noise channels, such as arises in some indoor and outdoor mobile communications channels. We develop a general expression for the Cramer-Rao bound (CRB) for direction finding using arrays for deterministic signals plus i.i.d. non-Gaussian noise, generalizing the Gaussian CRB. The CRBs for the noise and direction parameters decouple. The CRB for direction finding is expressed as a product of two terms that depend on the noise distribution, and the signal, respectively. We illustrate the results for a Gaussian mixture PDF, and present simulation results comparing five direction finding algorithms. An approach based on the expectation-maximization (EM) algorithm, that simultaneously estimates the noise parameters, the signal directions, and the signal waveforms, is shown to achieve the CRB over a wide SNR range.
Recognition of Pornographic Web Pages by Classifying Texts and Images
Authors: Weiming Hu Ou Wu Zhouyao Chen Zhouyu Fu Steve Maybank
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (2007)

With the rapid development of the World Wide Web, people benefit more and more from the sharing of information. However, Web pages with obscene, harmful, or illegal content can be easily accessed. It is important to recognize such unsuitable, offensive, or pornographic Web pages. In this paper, a novel framework for recognizing pornographic Web pages is described. A C4.5 decision tree is used to divide Web pages, according to content representations, into continuous text pages, discrete text pages, and image pages. These three categories of Web pages are handled, respectively, by a continuous text classifier, a discrete text classifier, and an algorithm that fuses the results from the image classifier and the discrete text classifier. In the continuous text classifier, statistical and semantic features are used to recognize pornographic texts. In the discrete text classifier, the naive Bayes rule is used to calculate the probability that a discrete text is pornographic. In the image classifier, the object's contour-based features are extracted to recognize pornographic images. In the text and image fusion algorithm, the Bayes theory is used to combine the recognition results from images and texts. Experimental results demonstrate that the continuous text classifier outperforms the traditional keyword-statistics-based classifier, the contour-based image classifier outperforms the traditional skin-region-based image classifier, the results obtained by our fusion algorithm outperform those by either of the individual classifiers, and our framework can be adapted to different categories of Web pages.
An extension of multidimensional synchronous dataflow to handle arbitrary sampling lattices
Authors: P. K. Murthy
Venue: Proceedings of the Acoustics, Speech, and Signal Processing, 1996. on Conference Proceedings., 1996 IEEE International Conference - Volume 06 (1996)

Multidimensional synchronous dataflow (MDSDF) is a model of computation that has been proposed and implemented for specifying multidimensional multirate signal processing systems such as image and video processing algorithms. The model is an extension of synchronous dataflow (SDF) and has all of the desirable properties of the SDF model such as static schedulability, exposure of data and functional parallelism and a visually pleasing syntax well suited for block diagram signal processing environments such as Ptolemy and Khoros. However, the MDSDF model as specified by Lee (1993) is limited to modeling multidimensional systems sampled on the rectangular lattice. Since some multidimensional systems of practical interest use non-rectangular sampling lattices and non-rectangular multirate operators like hexagonal decimators, models that are capable of representing and simulating such systems are of interest. This paper describes an extension of the MDSDF model that allows signals on arbitrary sampling lattices to be represented, and that allows the use of non-rectangular downsamplers and upsamplers.
Accurate Breast Region Detection in Digital Mammograms Using a Local Adaptive Thresholding Method
Authors: Maysam B. K. Shahedi, Rassoul Amirfattahi, Farah Torkamani Azar, Saeed Sadri
Venue: Proceedings of the Eight International Workshop on Image Analysis for Multimedia Interactive Services (2007)

Recently Computer Aided Diagnosis (CAD) systems have improved diagnosis of abnormalities in mammogram images. To improve the accuracy and reliability of such systems, the exact breast region as the region of interest (ROI), has to be segmented. Furthermore, focus on ROI can eliminates the effect of image background noise. Consequently it can reduce the detection algorithms execution time. Also, the accurate breast region detection ends to the accurate breast border detection, which can improve clinical diagnosis of abnormalities. Currently, new methods have been presented that achieve the accurate breast border detection. Nevertheless most of these methods are complicated and have undesirable effects on the execution time. In this paper we proposed a novel approach for accurate breast region segmentation in digital mammograms based on local thresholds. The suggested method can extract the breast region accurately.
Routing and scheduling in multihop wireless networks with time-varying channels
Authors: Matthew Andrews, Lisa Zhang
Venue: ACM Transactions on Algorithms (TALG) (2007)

We study routing and scheduling in multihop wireless networks. When data is transmitted from its source node to its destination node it may go through other wireless nodes as intermediate hops. The data transmission is node constrained, that is, every node can transmit data to at most one neighboring node per time step. The transmission rates are time varying as a result of changing wireless channel conditions. In this article, we assume that data arrivals and transmission rates are governed by an adversary. The power of the adversary is limited by an admissibility condition which forbids the adversary from overloading any wireless node a priori. The node-constrained transmission and time-varying nature of the transmission rates make our model different from and harder than the standard adversarial queueing model which relates to wireline networks. For the case in which the adversary specifies the paths that the data must follow, we design scheduling algorithms that ensure network stability. These algorithms try to give priority to the data that is closest to its source node. However, at each time step only a subset of the data queued at a node is eligible for scheduling. One of our algorithms is fully distributed. For the case in which the adversary does not dictate the data paths, we show how to route data so that the admissibility condition is satisfied. We can then schedule data along the chosen paths using our stable scheduling algorithms.