ppxscal/embedding_network huggingface dataset:
Efficient algorithms for approximating maximum inscribed sphere in high dimensional polytopes
Authors: Jinhui Xu
Venue:  (2008)

Computing maximum inscribed sphere (MaxIS) in high dimensional polytope is a fundamental problem in theorectical computer science, combinatorial optimization, and operation research, and is closely related to the maximum inscribed ellipsoid (MaxIE) problem which is the core problem of interior-point methods for linear programming (LP). One commonly used approach for solving the MaxIS problem is to reduce it to a linear programming (LP) problem with one more dimension and then use existing LP algorithms to solve it. Thus optimally solving the MaxIS problem could be rather costly (i.e., has the same complexity as an LP problem and takes O(n3.5 L) time using the best-known interior-point algorithm, where L is the size of the LP problem). Due to their importance, both problems have been extensively studied in the past. In this dissertation, we present efficient algorithms for computing a (1 &ndash; &epsis;)-approximation of the MaxIS. Given a bounded polytope P defined by nd-dimensional halfspaces, an interior point O of P, and a constant &epsis;>0, compute an inscribed sphere B of P with radius no smaller than (1 &ndash; &epsis;)Ropt, where Ropt is the radius of the maximum inscribed sphere of P. For polytopes with constant aspect ratio polytopes (also called fat polytopes), we provide an efficient algorithm with complexity O(nd/&epsis;3). For other polytopes, our algorithm takes O(((n + 1/&epsis;) nd/&epsis;2) log &alpha;) time, where &alpha; is the aspect ratio of the polytope. The dependence of our algorithms on the aspect ratio in the time complexities is only logarithmic. To our best knowledge, our algorithms are the first approximation solutions with linear complexity in d and quadratic in n, which is significantly faster than the traditional way of solving the MaxIS problem. Our algorithm is based on the core-set concept and a number of interesting geometric observations. Our result solves a special case of an open problem posted by Khachiyan and Todd in 1993 in which a geometric transform is sought to reduce an MaxIE to an MinEE (i.e., Maximum Enclosing Ellipsoid). Our results give an efficient geometric transformation to reduce MaxIS to MinES (Minimum Enclosing Sphere).
Development of tolerant features for characterization of masses in mammograms
Authors: Alfonso Rojas-Domínguez, Asoke K. Nandi
Venue: Computers in Biology and Medicine (2009)

In this paper, four new features for the analysis of breast masses are presented. These features were designed to be insensitive to the exact shape of the contour of the masses, so that an approximate contour, such as the one extracted via an automated segmentation algorithm, can be employed in their computation. Two of the features, Sp"S"I and Sp"G"O, measure the degree of spiculation of a mass and its likelihood of being spiculated. One of these features, Sp"G"O, is a measure of the relative gradient orientation of pixels that correspond to possible spicules. The other feature, Sp"S"I, is based on a comparison of mutual information measures between selected components of the mammographic images. The last two features, Fz"1 and Fz"2, measure the local fuzziness of the mass margins based on points defined automatically. The features were tested for characterization (i.e. discrimination between circumscribed and spiculated masses) and diagnosis (i.e. discrimination between benign and malignant masses) of breast masses using a set of 319 masses and three different classifiers. In the characterization experiments the features produced a result of approximately 89% correct classification. In the diagnosis experiments, the performance achieved was approximately 81% of correct classification.
Bi-directional Prediction between Weld Penetration and Processing Parameters in Electron Beam Welding Using Artificial Neural Networks
Authors: Xianfeng Shen, Wenrong Huang, Chao Xu, Xingjun Wang
Venue: Proceedings of the 6th International Symposium on Neural Networks: Advances in Neural Networks - Part III (2009)

The bi-directional prediction between processing parameters and weld penetration benefits electron beam welding (EBW) production by reducing costly trials. An artificial neural network (ANN) model was established for the bi-directional prediction between them in EBW. The main processing parameters consist of accelerating voltage, beam current and welding speed, while weld penetration indicates penetration depth and penetration width of weld. The training and test sets were collected through EBW experiments by using 1Cr18Ni9Ti stainless steel. Two-layer supervised neural networks were used with different number of hidden layer nodes. Comparison between experimental and predicted results show the maximum absolute-value error is 6.6% in forward prediction from the main processing parameters to weld penetration, while that is 23.6% in backward prediction reversely. Combined the higher accurate forward prediction with the easy-use backward prediction in EBW production, a flow chart is proposed for optimizing prediction of processing parameters.
Semantic hashing
Authors: Ruslan Salakhutdinov, Geoffrey Hinton
Venue: International Journal of Approximate Reasoning (2009)

We show how to learn a deep graphical model of the word-count vectors obtained from a large set of documents. The values of the latent variables in the deepest layer are easy to infer and give a much better representation of each document than Latent Semantic Analysis. When the deepest layer is forced to use a small number of binary variables (e.g. 32), the graphical model performs ''semantic hashing'': Documents are mapped to memory addresses in such a way that semantically similar documents are located at nearby addresses. Documents similar to a query document can then be found by simply accessing all the addresses that differ by only a few bits from the address of the query document. This way of extending the efficiency of hash-coding to approximate matching is much faster than locality sensitive hashing, which is the fastest current method. By using semantic hashing to filter the documents given to TF-IDF, we achieve higher accuracy than applying TF-IDF to the entire document set.
Robust synchronization of absolute and difference clocks over networks
Authors: Darryl Veitch, Julien Ridoux, Satish Babu Korada
Venue: IEEE/ACM Transactions on Networking (TON) (2009)

We present a detailed re-examination of the problem of inexpensive yet accurate clock synchronization for networked devices. Based on an empirically validated, parsimonious abstraction of the CPU oscillator as a timing source, accessible via the TSC register in popular PC architectures, we build on the key observation that the measurement of time differences, and absolute time, requires separate clocks, both at a conceptual level and practically, with distinct algorithmic, robustness, and accuracy characteristics. Combined with round-trip time based filtering of network delays between the host and the remote time server, we define robust algorithms for the synchronization of the absolute and difference TSCclocks over a network. We demonstrate the effectiveness of the principles, and algorithms using months of real data collected using multiple servers. We give detailed performance results for a full implementation running live and unsupervised under numerous scenarios, which show very high reliability, and accuracy approaching fundamental limits due to host system noise. Our synchronization algorithms are inherently robust to many factors including packet loss, server outages, route changes, and network congestion.
A Model of Database Components and their Interconnection Based upon Communicating Views
Authors: Stephen J. Hegner
Venue: Proceeding of the 2008 conference on Information Modelling and Knowledge Bases XIX (2008)

A formalism for constructing database schemata from simple components is presented in which the components are coupled to one another via communicating views. The emphasis is upon identifying the conditions under which such components can be interconnected in a conflict-free fashion, and a characterization of such, based upon the acyclicity of an underlying hypergraph, is obtained. The work is furthermore oriented towards an understanding of how updates can be supported within the component-based framework, and initial ideas of so-called canonical liftings are presented.
A conceptual model of m-commerce customers' continuance intention based on the customers' perceived value
Authors: Xiaobo Wu, Qi Chen, Lingling Sheng, Ying Wang
Venue: International Journal of Mobile Learning and Organisation (2009)

In the research field of mobile commerce (m-commerce), attention is focused on customers' adoption of m-commerce. However, the success of enterprises depends on customers' long-term use. In this paper, through contrasting the dimensions of customers' perceived value and factors that affect the m-commerce customer's behaviour, we propose the dimensions of m-commerce customer's perceived value and the conceptions of these dimensions. Based on the key conception of m-commerce customers' perceived value, we extend the expectation-confirmation model for information technology and build a conceptual model of m-commerce customers' continuance intention.
PHP Website Programming: Problem - Design - Solution
Authors: Jeremy Johnstone, Marco Bellinaso
Venue:  (2009)

PHP Website Programming: Problem Design Solution builds and implements a real-world PHP web site using the core features of PHP. It is a general-purpose, data-driven, content-based site that can be easily modified to meet the needs of many real sites you'll develop as a professional site developer. After introducing the overall approach and architecture for the n-tier design of the site, each chapter of the book discusses the business rationale behind the site features being developed in the chapter. After this business problem is explained, the chapter describes the technical features needed to solve the problem, including some background that will be useful to experienced PHP developers. From there, the chapter produces and discusses the code of the solution. The chapters and individual site features are not designed to be developed independently, but rather as part of a whole, just as a complete site would normally be developed in a real setting. The book doesn't hide difficult problems to make the solution simpler, rather it tackles them head on so that the solution is robust enough to really use. Some of the features in the site include: Membership and user profiles Content management system for news, article management, photos Opinion polls newsletters ecommerce with support for real-time credit card processing Forums Downloads Photo gallery Personalization Localization Advertising
Separability of spatial manipulations in multi-touch interfaces
Authors: Miguel A. Nacenta, Patrick Baudisch, Hrvoje Benko, Andy Wilson
Venue: Proceedings of Graphics Interface 2009 (2009)

Multi-touch interfaces allow users to translate, rotate, and scale digital objects in a single interaction. However, this freedom represents a problem when users intend to perform only a subset of manipulations. A user trying to scale an object in a print layout program, for example, might find that the object was also slightly translated and rotated, interfering with what was already carefully laid out earlier. We implemented and tested interaction techniques that allow users to select a subset of manipulations. Magnitude Filtering eliminates transformations (e.g., rotation) that are small in magnitude. Gesture Matching attempts to classify the user's input into a subset of manipulation gestures. Handles adopts a conventional single-touch handles approach for touch input. Our empirical study showed that these techniques significantly reduce errors in layout, while the Handles technique was slowest. A variation of the Gesture Matching technique presented the best combination of speed and control, and was favored by participants.
Incremental state based diagnosis
Authors: George M. Coghill, Guofu Wu
Venue: Advanced Engineering Informatics (2009)

In this paper we present an incremental diagnostic engine: IMBDE. IMBDE utilises qualitative models, and combines an extended version of Nayak and Williams' ITMS (based on root antecedents) with an incremental version of Reiter's Hitting Set Algorithm to perform incremental state based diagnosis on dynamic process systems. The approach is demonstrated to work by application to an industrial process - an ammonia washer system.
Coverage path planning algorithms for agricultural field machines
Authors: Timo Oksanen, Arto Visala
Venue: Journal of Field Robotics (2009)

In this article, a coverage path planning problem is discussed in the case of agricultural fields and agricultural machines. Methods and algorithms to solve this problem are developed. These algorithms are applicable to both robots and human-driven machines. The necessary condition is to cover the whole field, and the goal is to find as efficient a route as possible. As yet, there is no universal algorithm or method capable of solving the problem in all cases. Two new approaches to solve the coverage path planning problem in the case of agricultural fields and agricultural machines are presented for consideration. Both of them are greedy algorithms. In the first algorithm the view is from on top of the field, and the goal is to split a single field plot into subfields that are simple to drive or operate. This algorithm utilizes a trapezoidal decomposition algorithm, and a search is developed of the best driving direction and selection of subfields. This article also presents other practical aspects that are taken into account, such as underdrainage and laying headlands. The second algorithm is also an incremental algorithm, but the path is planned on the basis of the machine's current state and the search is on the next swath instead of the next subfield. There are advantages and disadvantages with both algorithms, neither of them solving the problem of coverage path planning problem optimally. Nevertheless, the developed algorithms are remarkable steps toward finding a way to solve the coverage path planning problem with nonomnidirectional vehicles and taking into consideration agricultural aspects. &copy; 2009 Wiley Periodicals, Inc.
Norm Defeasibility in an Institutional Normative Framework
Authors: Henrique Lopes Cardoso, Eugénio Oliveira
Venue: Proceeding of the 2008 conference on ECAI 2008: 18th European Conference on Artificial Intelligence (2008)

Normative environments have been proposed to regulate agent interaction in open multi-agent systems. However, most approaches rely on pre-imposed regulations that agents are subject to. Taking a different stance, we focus on a normative framework that assists agents in establishing by themselves their own commitment norms. With that aim in mind, a model of norm defeasibility is presented that enables exploiting and adapting a normative background to different extents. We formalize the normative state using first-order logic and define rules and norms operating on that state. A suitable semantics regarding the use of norms within a hierarchical context structure is given, based on norm activation conflict and defeasibility.
Improvement of BitTorrent Performance and Inter-domain Traffic by Inserting ISP-Owned Peers
Authors: Ioanna Papafili, Sergios Soursos, George D. Stamoulis
Venue: Proceedings of the 6th International Workshop on Internet Charging and Qos Technologies: Network Economics for Next Generation Networks (2009)

Large volumes of Internet traffic are nowadays generated by BitTorrent. In this article, we propose the insertion of high-bandwidth ISP-owned peers as an optimization approach to improve end-users' performance and reduce inter-domain traffic. An ISP-owned peer participates in BitTorrent swarms in order to download chunks and subsequently serve regular peers. We have run simulations on the ns-2 platform showing that our approach results in considerable reduction of both inter-domain traffic and the downloading times of users. We also show that the insertion of an ISP-owned peer can complement effectively the use of locality awareness, and lead to further performance improvements.
Postprocessing in Automated Grading Systems, Part 1
Authors: Peter A. Knipp, S. Raj Chaudhury
Venue: Computing in Science and Engineering (2009)

In this first installment on postprocessing, we discuss the manner in which the standard grading algorithm can be generalized in order to increase the power and effectiveness of automated grading systems.
Information theoretic measures for clusterings comparison: is a correction for chance necessary?
Authors: Nguyen Xuan Vinh, Julien Epps, James Bailey
Venue: Proceedings of the 26th Annual International Conference on Machine Learning (2009)

Information theoretic based measures form a fundamental class of similarity measures for comparing clusterings, beside the class of pair-counting based and set-matching based measures. In this paper, we discuss the necessity of correction for chance for information theoretic based measures for clusterings comparison. We observe that the baseline for such measures, i.e. average value between random partitions of a data set, does not take on a constant value, and tends to have larger variation when the ratio between the number of data points and the number of clusters is small. This effect is similar in some other non-information theoretic based measures such as the well-known Rand Index. Assuming a hypergeometric model of randomness, we derive the analytical formula for the expected mutual information value between a pair of clusterings, and then propose the adjusted version for several popular information theoretic based measures. Some examples are given to demonstrate the need and usefulness of the adjusted measures.
A view upon redundancy in wireless sensor networks
Authors: Daniel-Ioan Curiac, Constantin Volosencu, Dan Pescaru, Lucian Jurca, Alexa Doboli
Venue: Proceedings of the 8th WSEAS international conference on Signal processing, robotics and automation (2009)

This paper presents and classifies different approaches for redundancy in the area of wireless sensor networks, related to sensing, communication and measurement information. Sometimes an ally, sometimes a foe, redundancy is an inherent feature of sensor networks that has to be very carefully examined in order to improve important aspects of their functioning. Moreover, this paper presents the fields in which the redundancy could be applied with significant results.
A Discrete-Time Recurrent Neural Network with One Neuron for k-Winners-Take-All Operation
Authors: Qingshan Liu, Jinde Cao, Jinling Liang
Venue: Proceedings of the 6th International Symposium on Neural Networks on Advances in Neural Networks (2009)

In this paper, a discrete-time recurrent neural network with one neuron and global convergence is proposed for k-winners-take-all (kWTA) operation. Comparing with the existing kWTA networks, the proposed network has simpler structure with only one neuron. The global convergence of the network can be guaranteed for kWTA operation. Simulation results are provided to show that the outputs vector of the network is globally convergent to the solution of the kWTA operation.
Auctioning Vertically Integrated Online Services: Computational Approaches for Real-Time Allocation
Authors: Ravi Bapna, Paulo Goes, Alok Gupta
Venue: Journal of Management Information Systems (2008)

We develop three auction-based pricing and allocation solution methods for the case where a capacity-constrained online service provider offers multiple classes of unique, one-time services with differentiated quality. Consumers desire exactly one of the many service classes offered. We call such a setting a vertically integrated online services market. Examples of these services are webcasting of special events over the Internet, provision of video-on-demand, and allocation of grid computing resources. We model the pricing and allocation decision faced by firms in such a setting as a knapsack problem with an added preference elicitation dimension. We present a variety of computational solution approaches based on adaptations of the traditional greedy heuristic for knapsack problems. The solution approaches vary in efficacy depending on whether bidders are restricted to bid in one service class or allowed to bid in multiple service classes, as well as on the overall variability of the demand. In the case bidders can bid in multiple classes but are interested in consuming only one service class, a direct application of the heuristics developed for the single service case results in a nonfair allocation. We develop a novel data structure to eliminate the unfair allocation while maintaining the original computation complexity of the simpler setting. The paper contributes by presenting a menu of auction clearing mechanisms for selling vertically integrated online services.
The Effect of Open Student Model on Learning: A Study
Authors: Amruth Kumar, Adrian Maries
Venue: Proceeding of the 2007 conference on Artificial Intelligence in Education: Building Technology Rich Learning Contexts That Work (2007)

We conducted a within-subjects study of the effect on student learning of using open student model in the form of taxonomic concept map. We found a significant improvement in learning on two questions related to the topic of the tutor, and no pre-post improvement on questions unrelated to the topic of the tutor. These preliminary results suggest that students may learn concepts indirectly by viewing the open student model presented as taxonomic concept map after each problem.
An adaptive online system for efficient processing of hierarchical data
Authors: Athanasia Asiki, Dimitrios Tsoumakos, Nectarios Koziris
Venue: Proceedings of the 18th ACM international symposium on High performance distributed computing (2009)

Concept hierarchies greatly help in the organization and reuse of information and are widely used in a variety of information systems applications. In this paper, we describe a method for efficiently storing and querying data organized into concept hierarchies and dispersed over a DHT. In our method, peers individually decide on the level of indexing according to the granularity of the incoming queries. Roll-up and drill-down operations are performed on a per-node basis in order to minimize the required bandwidth for answering queries on variable aggregation levels. We motivate our approach by applying it on a large-scale Grid system: Specifically, we plan to apply our fully decentralized scheme that creates, queries and updates large volumes of hierarchical data on-line and replace the traditional centralized and strictly indexed information systems. Our extensive experimental results support this argument on many diverse configurations: Our system proves very efficient in skewed workloads, both over single and multiple hierarchy levels at the same time. It adapts to sudden changes in popularity and effectively stores and updates large amounts of data at very low cost.
Installing Linux on a Dead Badger
Authors: Lucy A. Snyder
Venue:  (2007)

Installing Linux on a Dead Badger (and Other Oddities) contains a dozen stories to amuse any fan of technology humor or science fictional dark comedy. Many of the stories are what Green Man Review has dubbed "cyberzombie humor"; the title story is one of the most popular features ever posted at the acclaimed science fiction magazine Strange Horizons. The satiric tales are accompanied by 14 black-and-white illustrations from DE Christman and Malcolm McClinton. Teen Linux gang mayhem. Trolls gone wild. A vampire's guide to management. Your corporate network and the forces of darkness. And much more .... 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