ppxscal/embedding_network huggingface dataset:
Common refactorings, a dependency graph and some code smells: an empirical study of Java OSS
Authors: S. Counsell, Y. Hassoun, G. Loizou, R. Najjar
Venue: Proceedings of the 2006 ACM/IEEE international symposium on Empirical software engineering (2006)

Refactoring, as a software engineering discipline has emerged over recent years to become an important aspect of maintaining software. Refactoring refers to the restructuring of software according to specific mechanics and principles. In this paper, we describe an analysis of the results from a tool whose purpose was to identify and extract refactorings from seven open-source Java systems. In particular, we analyzed the mechanics of the most commonly and least commonly applied refactorings to try and account for their frequency. Results showed the most common refactorings of the fifteen coined a 'Gang of Six', to be generally those with a high in-degree and low out-degree when mapped on a dependency graph; the same refactorings also featured strongly in the remedying of bad code smells. Remarkably and surprisingly, inheritance and encapsulationbased refactorings were found to have been applied relatively infrequently - we offer explanations for why this may be the case. The paper thus identifies 'core' refactorings central to many of the changes made by developers on open-source systems. While we can not guarantee that developers consciously undertake refactoring in any sense, the empirical results demonstrate that simple renaming and moving fields/methods between classes are common components of open-source system re-engineering. From a wider software engineering perspective, knowledge of what a modification will incur in likely sub-tasks is of value to developers whether working on open-source or other forms of software.
The BlueGene/L pseudo cycle-accurate simulator
Authors: L. R. Bachega, J. R. Brunheroto, L. DeRose, P. Mindlin, J. E. Moreira
Venue: Proceedings of the 2004 IEEE International Symposium on Performance Analysis of Systems and Software (2004)

The design and development of a new computer system is a lengthy process, with a considerable amount of time elapsed between the beginning of development and first hardware availability. Hence, fast and reasonably accurate simulation of processor architecture has become critical as an enabling mechanism for software engineers to develop and tune system software and applications. In this paper, we present the time-stamped timing model extensions to the BlueGene/L functional simulator. These extensions were implemented to create a pseudo cycle-accurate simulator capable of providing tracing capabilities for detection of bottlenecks and for performance tuning of applications, before the actual hardware became available. Our validation tests, using the DAXPY kernel and the serial version of the NAS benchmarks, show that our pseudo cycle-accurate simulator provides timing information within 15% of the times measured using the actual BlueGene/L hardware. In addition, we present a couple of case studies, which describes how this simulator can be used for identification of performance bottlenecks and for application tuning.
Local or Global Minima: Flexible Dual-Front Active Contours
Authors: Hua Li, Anthony Yezzi
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (2007)

Most variational active contour models are designed to find local minima of data-dependent energy functionals with the hope that reasonable initial placement of the active contour will drive it toward a "desirable” local minimum as opposed to an undesirable configuration due to noise or complex image structure. As such, there has been much research into the design of complex region-based energy functionals that are less likely to yield undesirable local minima when compared to simpler edge-based energy functionals whose sensitivity to noise and texture is significantly worse. Unfortunately, most of these more "robust” region-based energy functionals are applicable to a much narrower class of imagery compared to typical edge-based energies due to stronger global assumptions about the underlying image data. Devising new implementation algorithms for active contours that attempt to capture more global minimizers of already proposed image-based energies would allow us to choose an energy that makes sense for a particular class of energy without concern over its sensitivity to local minima. Such implementations have been proposed for capturing global minima. However, sometimes the completely-global minimum is just as undesirable as a minimum that is too local. In this paper, we propose a novel, fast, and flexible dual front implementation of active contours, motivated by minimal path techniques and utilizing fast sweeping algorithms, which is easily manipulated to yield minima with variable "degrees” of localness and globalness. By simply adjusting the size of active regions, the ability to gracefully move from capturing minima that are more local (according to the initial placement of the active contour/surface) to minima that are more global allows this model to more easily obtain "desirable” minimizers (which often are neither the most local nor the most global). Experiments on various 2D and 3D images and comparisons with some active contour models and region-growing methods are also given to illustrate the properties of this model and its performance in a variety of segmentation applications.
Guest Editor's Introduction: Educating the Next Generation of Game Developers
Authors: Michael Zyda
Venue: Computer (2006)

To advance the state of the art of game technology, many universities have begun new degree programs focused on game design and development. This special issue profiles four programs that are exploring this emerging and important discipline and have proposed similar--or even novel--solutions to the challenges it presents.
Principal Component Analysis of Multi-view Images for Viewpoint-Independent Face Recognition
Authors: Takio Kurita, Tatsuya Hosoi, Akinori Hidaka
Venue: Proceedings of the IEEE International Conference on Video and Signal Based Surveillance (2006)

We consider the problem of recognizing a specific human face in different poses (viewing direction) when only one frontal face image exists in the face database. To solve this problem, prior knowledge is learned by using principal component analysis on a set of multi-view images to obtain aligned principal components. They are used together with the idea of linear object classes to synthesize a virtual view of the frontal face from a given face image taken from a different viewing direction. The estimated virtual frontal view is then compared with the stored frontal face images in the face database to identify the person. Experimental results are shown using face images captured from different viewpoints.
A Conceptual Framework for Business Process Engineering: A Case Study
Authors: Zeljka Car, Hrvoje Belani, Antun Caric
Venue: Proceedings of the International Conference on Software Engineering Advances (2006)

this paper discusses a conceptual framework for the requirements engineering process for e-school applications offering a service to the information society. The e-school application is considered a fusion of the electronic business and mobile business contexts, containing three dynamic Webinterfaces and an SMS-interface. Implementation of this service requires changes in the school business process it supports. This paper presents a requirements engineering framework which aims at resolving the feedback loop between the application and the business process. The presented framework has been defined in order to help simultaneously develop an application which provides the service and ensures the necessary identification of school business process changes and their models. The framework also provides a mechanism for efficient service deployment and its future evolution without adverse effects on the underlying business process. Presented is a case study for an e-school notification service implemented within this framework.
Mixed-integer linear programming for transition-independent decentralized MDPs
Authors: Jianhui Wu, Edmund H. Durfee
Venue: Proceedings of the fifth international joint conference on Autonomous agents and multiagent systems (2006)

Markov decision process (MDP) provides a framework for computing optimal policies for individual agents operating in uncertain environments. However, extending single-agent MDP techniques to multiagent problems is not straightforward. Previous complexity analyses have shown that the general decentralized Markov decision process (Dec-MDP) is NEXP-complete, which means that optimally solving a Dec-MDP is extremely difficult. The class of problems studied in this paper is a subclass of Dec-MDP in which two or more cooperative agents are tied together through the rewards of completing joint tasks but the actions taken by one agent do not impact other agents' transitions. Although this reduces the complexity class to NP-complete [4], efficiently solving such transition independent Dec-MDPs is still nontrivial.
YAM2: a multidimensional conceptual model extending UML
Authors: Alberto Abelló, José Samos, Fèlix Saltor
Venue: Information Systems (2006)

This paper presents a multidimensional conceptual Object-Oriented model for Data Warehousing and OLAP tools, its structures, integrity constraints and query operations. It has been developed as an extension of UML core metaclasses to facilitate its usage, and try to fill the absence of a standard model. Being a UML extension allows reusing modeling constructs and techniques, and integrating multidimensional modeling in more general modeling processes. Moreover, while existing multidimensional models are restricted to the modeling of isolated stars, this paper investigates the representation of several semantically related star schemas. Summarizability and identification constraints can also be represented in the model, and a closed and complete set of algebraic operations has been defined in terms of functions (so that mathematical properties of functions can be smoothly applied).
Kernel Spectral Matched Filter for Hyperspectral Imagery
Authors: Heesung Kwon, Nasser M. Nasrabadi
Venue: International Journal of Computer Vision (2007)

In this paper a kernel-based nonlinear spectral matched filter is introduced for target detection in hyperspectral imagery, which is implemented by using the ideas in kernel-based learning theory. A spectral matched filter is defined in a feature space of high dimensionality, which is implicitly generated by a nonlinear mapping associated with a kernel function. A kernel version of the matched filter is derived by expressing the spectral matched filter in terms of the vector dot products form and replacing each dot product with a kernel function using the so called kernel trick property of the Mercer kernels. The proposed kernel spectral matched filter is equivalent to a nonlinear matched filter in the original input space, which is capable of generating nonlinear decision boundaries. The kernel version of the linear spectral matched filter is implemented and simulation results on hyperspectral imagery show that the kernel spectral matched filter outperforms the conventional linear matched filter.
Hybrid video downloading/streaming over peer-to-peer networks
Authors: Yufeng Shan, S. Kalyanaraman
Venue: Proceedings of the 2003 International Conference on Multimedia and Expo - Volume 1 (2003)

Peer-to-peer based multimedia delivery is becoming increasingly more important in today's networks. Using a peer- to-peer network to assist video streaming is a topic of considerable interest. In this paper, we propose a novel hybrid video downloading/streaming scheme (HDS) that efficiently integrates traditional client/server based video streaming and peer-to-peer based media distribution. Furthermore, we propose a receiver-driven algorithm to coordinate the downloading and streaming modes; and control the state transitions between these modes. We have performed real-world experiments and simulations to validate our concept. These results show that our proposed scheme greatly increases the availability of video content on the receiver side and simultaneously reduces the server load significantly.
Architecture of a Self-Checkpointing Microprocessor that Incorporates Nanomagnetic Devices
Authors: Love Kothari, Nicholas P. Carter
Venue: IEEE Transactions on Computers (2007)

Memory and latch circuits in CMOS systems rely on capacitatively-stored charge to hold state information. When power is removed from a chip, this charge quickly drains off, destroying any information that was contained in the chip. This causes a number of problems for computer systems, including data loss from power failures, the need to load operating systems from nonvolatile storage each time the system is powered on, and high "idle” power consumption due to leakage currents in memory arrays. Magnetoelectronic devices that combine ferromagnetic elements with semiconductor structures have the potential to overcome this limitation by providing high-performance nonvolatile storage that can be tightly integrated with logic. In this paper, we present the architecture of a microprocessor that uses magnetoelectronic devices to "snapshot” the state of the currently executing program at regular intervals. If its power supply is interrupted, this self-checkpointing microprocessor can near instantly restore its state from the last checkpoint, allowing it to resume execution with little loss of progress. Simulations of a self-checkpointing version of the Pentium 4 microprocessor show that the magnetoelectronic memories increase power consumption by only 62 mW, with little to no cost in system performance.
An Informatics-Based Managed Learning Environment MLE For Research and Learning at UCDavis CRISP, The Instructional Systems Design ISD Approach
Authors: Maria Lorna A. Kunnath, Peter Yellowlees
Venue: Proceedings of the Sixth IEEE International Conference on Advanced Learning Technologies (2006)

This paper describes the main concept depicted in a recent grant proposal submitted by UCDavis to the National Institute of Health NIH January 31, 2006 to improve the education and training of the School of Medicine researchers at UCDavis. The proposal posits that a managed learning (informatics-rich) environment MLE will enhance the education and continuous training of researchers by allowing them access to rich learning research resources through specialized software and databases not normally accessible to researchers while formulating ideas and theories, solving problems, and analyzing data.. The paper describes the proposed portal and more importantly, the evaluation component which will drive the continuous re-design of the syste
Automatic Cast Listing in Feature-Length Films with Anisotropic Manifold Space
Authors: Ognjen Arandjelovic, Roberto Cipolla
Venue: Proceedings of the 2006 IEEE Computer Society Conference on Computer Vision and Pattern Recognition - Volume 2 (2006)

Our goal is to automatically determine the cast of a feature-length film. This is challenging because the cast size is not known, with appearance changes of faces caused by extrinsic imaging factors (illumination, pose, expression) often greater than due to differing identities. The main contribution of this paper is an algorithm for clustering over face appearance manifolds. Specifically: (i) we develop a novel algorithm for exploiting coherence of dissimilarities between manifolds, (ii) we show how to estimate the optimal dataset-specific discriminant manifold starting from a generic one, and (iii) we describe a fully automatic, practical system based on the proposed algorithm. The performance of the system is evaluated on well-known featurelength films and situation comedies on which it is shown to produce good results.
Bipartite roots of graphs
Authors: Lap Chi Lau
Venue: ACM Transactions on Algorithms (TALG) (2006)

Graph H is a root of graph G if there exists a positive integer k such that x and y are adjacent in G if and only if their distance in H is at most k. Motwani and Sudan [1994] proved the NP-completeness of graph square recognition and conjectured that it is also NP-complete to recognize squares of bipartite graphs. The main result of this article is to show that squares of bipartite graphs can be recognized in polynomial time. In fact, we give a polynomial-time algorithm to count the number of different bipartite square roots of a graph, although this number could be exponential in the size of the input graph. By using the ideas developed, we are able to give a new and simpler linear-time algorithm to recognize squares of trees and a new algorithmic proof that tree square roots are unique up to isomorphism. Finally, we prove the NP-completeness of recognizing cubes of bipartite graphs.
Automatic Recognition of Text Difficulty from Consumers Health Information
Authors: Yunli Wang
Venue: Proceedings of the 19th IEEE Symposium on Computer-Based Medical Systems (2006)

Internet is used as one of major sources of health information. However, some studies show that the readability of health information presented on health web sites is difficult for many consumers. Readability formulas usually measure difficulty of writing style, instead of difficulty of content. In order to recommend health information with appropriate reading level to consumers, we investigate the feasibility of identifying text difficulty of health information using machine learning methods. Support Vector Machine is used to classify consumer health information into easy to read and reading level for the general public. Three feature sets: surface linguistic features, word difficulty features, unigrams and their combinations are compared in terms of classification accuracy. Unigram features alone reach an accuracy of 80.71%, and the combination of three feature sets is the most effective in classification with accuracy of 84.06%. They are significantly better than surface linguistic features, word difficulty features and their combination.
A square magnetic circuit analysis using Schwarz-Christoffel mapping
Authors: Miroslav Marković, Marcel Jufer, Yves Perriard
Venue: Mathematics and Computers in Simulation (2006)

The paper presents an original method to determine the 2D magnetic field in a square magnetic circuit. To do it, the method of Schwarz-Christoffel mapping is used. This mapping is a special kind of the conformal mappings, applicable to polygonal 2D configurations. As the magnetic circuit is complicated, a numerical solution has to be applied. Knowing the magnetic field, the fluxes and inductances are determined. The results are verified using FEM commercial software.
A comparison of multivariate autoregressive estimators
Authors: Alois Schlögl
Venue: Signal Processing (2006)

Recently, a new estimator--Arfit--for multivariate (vector) autoregressive (MVAR) parameters has been proposed. Several other MVAR estimators (e.g. Levinson recursion, Burg-type Nuttall-Strand, etc.) were already well known in the field of signal processing.The various MVAR estimators have been implemented for Octave and Matlab. A method based on cross-validation and bootstrapping has been developed for comparing the various estimators. Thousand realizations of a MVAR(6)-process with 5 channels and a length of 1000 samples were generated. Each realization was separated into training and a test period. The training period was used to estimate the MVAR-parameters with each algorithm; the testing period was used to probe the accuracy of the estimates.For large sample sizes, the Burg-type algorithm and Arfit yielded similar results, the multivariate Levinson method was worse. For small sample sizes, the Burg-type Nuttall-Strand method was signifcantly better than multivariate Levinson, the Arfit estimates performed worst.In summary, the Nuttall Strand method (multivariate Burg) for estimating MVAR parameters yielded the best results. The implementation of the algorithms for Octave and Matlab has been made available on the world wide web.
Conflicts in pedagogical and technical knowledge: pre-service teachers' understanding and misconception of integrating technology into PBL lessons
Authors: Hyo-Jeong So, Bosung Kim
Venue: Proceedings of the 7th international conference on Learning sciences (2006)

Fifty-one pre-service teachers' understandings and misconceptions of Information and Communications Technology (ICT) and Problem-based Learning (PBL) integration were examined in this study. Data from questionnaire and student projects were analyzed to identify the conceptual and practical difficulties integrating ICT tools into PBL lessons. While participants showed good theoretical understandings of PBL approaches, their lesson designs showed a mismatch between ICT tools and learning objectives, indicating conflicts in translating pedagogical knowledge into technology-integrated lessons.
On the Impact of Unwanted Traffic onto a 3G Network
Authors: Fabio Ricciato, Philipp Svoboda, Eduard Hasenleithner, Wolfgang Fleischer
Venue: Proceedings of the Second International Workshop on Security, Privacy and Trust in Pervasive and Ubiquitous Computing (2006)

The presence of "unwanted" (or background) traffic in the Internet is a well-known fact. In principle any network that has been engineered without taking into account the presence of unwanted traffic might experience troubles during periods of massive exposure to it, e.g. large-scale infections. A concrete example was provided by the spreading of Code-Red-II in 2001, which caused several routers crashes worldwide. Similar events might take place in 3G networks as well, with further potential complications due to the functional complexity and the scarcity of radio resources. In this explorative paper we show that unwanted traffic is present also in GPRS/UMTS, mainly due to the widespread use of 3G connect cards for laptops. Based on a mixture of real-world measurements and theoretical speculations, we investigate the potential impact of such traffic onto the underlying network. We show that under certain hypothetical network configuration settings unwanted traffic, and specifically scanning traffic from infected Mobile Stations, can cause large-scale wastage of logical resources, and in extreme cases starvation. We urge the research community and network operators to consider the issue of 3G robustness to unwanted traffic as a prominent research area. The goal of this paper is to trigger interest and at the same time move a first pioneering step in this direction.
Mechanically verifying correctness of CPS compilation
Authors: Ye Henry Tian
Venue: Proceedings of the 12th Computing: The Australasian Theroy Symposium - Volume 51 (2006)

In this paper, we study the formalization of one-pass call-by-value CPS compilation using higher-order abstract syntax. In particular, we verify mechanically that the source program and the CPS-transformed program have the same observable behavior. A key advantage of this approach is that it avoids any administrative redexes thereby simplifying the proofs about CPS-translations. The CPS translation together with its correctness proof is implemented and techanically verified in the logical framework Twelf.