ppxscal/embedding_network huggingface dataset:
A multiresolutional approach for large data visualization
Authors: Han-Wei Shen
Venue:  (2006)

The sizes of large data sets, ranging from gigabytes to terabytes, pose a formidable challenge to conventional volume visualization algorithms. Multiresolution rendering proves to be a viable solution to this challenge by reducing the actual amount of data sent to the rendering pipeline. However, previous multiresolution rendering algorithms are inherently sequential, which hinders their applications in parallel environments, such as PC clusters with increasing availability. Moreover, most of the existing algorithms for large volume visualization use data-based metrics for level-of-detail selection and provide very limited user interaction and control. There is lack of techniques and tools for more effective level-of-detail selection and rendering. I present a multiresolutional approach for representing, managing, selecting, and rendering large-scale three-dimensional steady and time-varying data sets. A multiresolution volume rendering algorithm is proposed to visualize large data sets in parallel environments that ensures a well-balanced workload. A comprehensive imagebased quality metric is introduced for quality-driven interactive level-of-detail selection and rendering of large data sets. Furthermore, a new visual navigation interface is presented for the user to examine, compare, and validate different level-of-detail selection algorithms. Future research focuses on transfer function design for large-scale time-varying data, which includes spatio-temporal data reduction, transfer function design, and user interface support for space-time data exploration.
An Asymmetric Quorum-based Power Saving Protocol for Clustered Ad Hoc Networks
Authors: Shan-Hung Wu, Chung-Min Chen, Ming-Syan Chen
Venue: Proceedings of the 27th International Conference on Distributed Computing Systems (2007)

Clustering in Mobile Ad Hoc Networks (MANETs) has shown to be a promising technique to ensure the scalability and efficiency of various communication protocols. Since stations in MANETs are usually equipped with batteries as the power source, it is critical to ensure the energy efficiency of clustering schemes. The Quorum-based Power Saving (QPS) protocols render extensive energy conservation as compared with IEEE 802.11 Power Saving (PS) mode and are widely studied over the past years. However, most existing QPS protocols adopt a symmetric design where stations in the network are guaranteed to discover each other. Observing that in clustered environments there is no need to insist in all-pair neighbor discovery, we propose an Asymmetric Cyclic Quorum (ACQ) system. The ACQ system guarantees the neighbor discovery between each member node and the clusterhead in a cluster, and between clusterheads in the network. A construction scheme is presented in this work, which assembles the ACQ system in O(1) time. We show that by taxing slightly more energy consumption on the clusterhead, the average energy consumption of stations in a cluster can reduce substantially than can be achieved by traditional QPS protocols. Simulation results show that the ACQ system outperforms the previous studies up to 52% in energy efficiency, while introducing no extra worst-case latency.
Exploiting parallelism to support scalable hierarchical clustering
Authors: Rebecca J. Cathey, Eric C. Jensen, Steven M. Beitzel, Ophir Frieder, David Grossman
Venue: Journal of the American Society for Information Science and Technology (2007)

A distributed memory parallel version of the group average hierarchical agglomerative clustering algorithm is proposed to enable scaling the document clustering problem to large collections. Using standard message passing operations reduces interprocess communication while maintaining efficient load balancing. In a series of experiments using a subset of a standard Text REtrieval Conference (TREC) test collection, our parallel hierarchical clustering algorithm is shown to be scalable in terms of processors efficiently used and the collection size. Results show that our algorithm performs close to the expected O(n2&sol;p) time on p processors rather than the worst-case O(n3&sol;p) time. Furthermore, the O(n2&sol;p) memory complexity per node allows larger collections to be clustered as the number of nodes increases. While partitioning algorithms such as k-means are trivially parallelizable, our results confirm those of other studies which showed that hierarchical algorithms produce significantly tighter clusters in the document clustering task. Finally, we show how our parallel hierarchical agglomerative clustering algorithm can be used as the clustering subroutine for a parallel version of the buckshot algorithm to cluster the complete TREC collection at near theoretical runtime expectations. &copy; 2007 Wiley Periodicals, Inc.
Multiscale representation for automatic identification of structures in medical images
Authors: M. S. Rebelo, S. S. Furuie, M. A. Gutierrez, E. T. Costa, L. A. Moura
Venue: Computers in Biology and Medicine (2007)

The identification of structures is a key step in several applications of medical imaging. In this work we propose a method for the identification of structures using a multiscale approach with inclusion of a priori information about the searched objects. After describing the image structures in the multiscale representation, a matching step determines which structure most likely corresponds to the target. Patterns are generated by previous application of the method to a set of images. We present a prototype for identifying structures in 2D images. A set of experiments was carried out to evaluate the prototype leading to encouraging results.
GETA sandals: a footstep location tracking system
Authors: Shun-Yuan Yeh, Keng-Hao Chang, Chon-In Wu, Hao-Hua Chu, Jane Yung-Jen Hsu
Venue: Personal and Ubiquitous Computing (2007)

This paper presents the design, implementation, and evaluation of a footstep based indoor location system. The traditional Japanese GETA sandals are equipped with force, ultrasonic, orientation, RFID sensors and an accelerometer to produce a wearable location tracking system that demand little infrastructure in the deployed environment. In its basic form, a user simply puts on GETA sandals to enable tracking of his/her locations relative to a starting point (e.g., a building entrance), making it easy for deployment everywhere. The footstep location system is based on dead-reckoning, which works by measuring and tracking displacement vectors along a trail of footsteps. Each displacement vector is formed by drawing a line between each pair of footsteps, and the position of a user can be calculated by summing up the current and all previous displacement vectors. Unlike most existing indoor location systems, the footstep based method does not suffer from problems with obstacles, multi-path effects, signal noises, signal interferences, and dead spots. There are two technical challenges in the proposed design: (1) location error accumulates over distance traveled, and (2) displacement measurements are sporadic during stair climbing. The first problem is addressed by a light RFID infrastructure, while the second problem is remedied by incorporating an accelerometer into the system. Experiments on GETA prototype are conducted to evaluate the positional accuracy of our system.
Dynamic enumeration algorithm using array antennas
Authors: P. J. Green
Venue: Proceedings of the Acoustics, Speech, and Signal Processing, 2001. on IEEE International Conference - Volume 05 (2001)

This paper develops a robust method to enumerate the incident signals impinging on a uniform but variable size linear array independent of their extent of correlation in a Rayleigh flat fading channel environment. The method also optimizes by minimizing the number of antennas to the number of signals and adapts continuously to maintain optimum performance in a mobile environment where users (signals) come and go. The technique is a modification of the matrix decomposition method of J.H. Cozzens and M.J. Sousa (see IEEE Transactions on Signal Processing, vol.42, no.2, p.304-17, 1994). A new set of stability, stopping and adaptive control criteria is presented. An algorithm is formulated with simulation and field results presented.
A multiresolution approach to blind separation of speech signals in a reverberant environment
Authors: M. Z. Ikram
Venue: Proceedings of the Acoustics, Speech, and Signal Processing, 2001. on IEEE International Conference - Volume 05 (2001)

The performance of existing blind speech separation methods is limited in a realistic reverberant environment, where a need for long un-mixing filters is imperative. We first show how these methods suffer while trying to balance the competing objectives of frequency-domain permutation alignment and spectral resolution. We then propose a multistage multiresolution algorithm, which aligns the un-mixing filter permutations over the whole frequency band without sacrificing spectral resolution. We perform experiments in both real and simulated reverberant environments, and obtain improved separation results that are comparable to the ideal benchmark obtained by aligning the permutations using prior knowledge of the mixing filters.
Extending Tcl for dynamic object-oriented programming
Authors: David Wetherall, Christopher J. Lindblad
Venue: Proceedings of the 3rd Annual USENIX Workshop on Tcl/Tk - Volume 3 (1995)

Object Tcl is an extension to the Tool Command Language (Tcl) for the management of complicated data types and dynamic object-oriented programming in general. We believe it is a worthy alternative to other object-oriented programming extensions (including [incr Tcl]) because it may be used dynamically, allows for per object specialization, has an economy of design and implementation, and provides a metaobject-based class system. Its design was driven by our VuSystem application needs to create a foundation with powerful abstraction and introspection capabilities, yet we sought to retain both the spirit and benefits of Tcl. This paper presents Object Tcl, emphasizing language design and implementation issues by comparing it with alternative systems.
Fast IPsec: a high-performance IPsec implementation
Authors: Samuel J. Leffler
Venue: Proceedings of the BSD Conference 2003 on BSD Conference (2003)

Fast IPsec is an implementation of the IPsec protocols [Kent & Atkinson, 1998a] for FreeBSD that was designed for high performance. In particular the protocols use the OpenBSD Cryptographic Framework, as ported to FreeBSD [Leffler, 2003], so any cryptographic hardware is automatically used to accelerate their operation. Fast IPsec, running on a uniprocessor system with a single Broadcom BCM5822 cryptographic processor, has demonstrated throughput of more than 400 megabits/second when acting as an IPsec terminator. This is more than 50% higher than any other freely available IPsec implementation.
Connection handoff policies for TCP offload network interfaces
Authors: Hyong-youb Kim, Scott Rixner
Venue: Proceedings of the 7th USENIX Symposium on Operating Systems Design and Implementation - Volume 7 (2006)

This paper presents three policies for effectively utilizing TCP offload network interfaces that support connection handoff. These policies allow connection handoff to reduce the computation and memory bandwidth requirements for packet processing on the host processor without causing the resource constraints on the network interface to limit overall system performance. First, prioritizing packet processing on the network interface ensures that its TCP processing does not harm performance of the connections on the host operating system. Second, dynamically adapting the number of connections on the network interface to the current load avoids overloading the network interface. Third, the operating system can predict connection lifetimes to select long-lived connections for handoff to better utilize the network interface. The use of the first two policies improves web server throughput by 12-31% over the baseline throughput achieved without offload. The third policy helps improve performance when the network interface can only handle a small number of connections at a time. Furthermore, by using a faster offload processor, offloading can improve server throughput by 33-72%.
Incorporating 3D modeling and visualization in the first year engineering curriculum
Authors: L. G. Richards
Venue: Proceedings of the Frontiers in Education Conference, on 1995. Proceedings., 1995 - Volume 02 (1995)

We describe how 3D modeling and visualization have been incorporated into a first year engineering concepts course at the University of Virginia. Previously we eliminated the traditional engineering graphics course and integrated that material into other courses. We now introduce geometric modeling, computer aided design, and the basic ideas of visualization to our students during their first semester. In their first CAD lesson, our students learn to construct a solid model, to view it from multiple perspectives and to render it. The second lesson introduces Boolean operations; the third, working in multiple spaces, the fourth, a variety of solid modeling techniques, and the fifth annotating a model. A sixth lesson covers the fundamental ideas of rendering. Thus, we start with three dimensional thinking and emphasize the importance of modeling and visualization to the engineering design process. Students find this approach exciting, challenging, and relevant. They learn to capture their ideas as 3D models, and gain an early understanding of the role of design in engineering.
An efficient power allocation strategy for low Earth-orbit satellite communication systems
Authors: Chia-Sheng Tsai, Szu-Lin Su
Venue: Proceedings of the The 8th International Conference on Communication Systems - Volume 02 (2002)

This paper proposes a method for efficiently allocating power to subscribers oil earth. The idea is that the users located closer to the center of a cell, which usually enjoy larger gain of satellite antenna and lower interference from surrounding beams, can request and get services at a higher data rate without much transmission power allocation, while the users located at the cell's boundary shall reduce the data-reception rate to save the power. A mathematical model is developed and the results show that the proposed scheme enables more traffic to be carried on a limited power resource of LEO satellite systems.
Interactive presentation: Single-ended coding techniques for off-chip interconnects to commodity memory
Authors: Mihir Choudhury, Kyle Ringgenberg, Scott Rixner, Kartik Mohanram
Venue: Proceedings of the conference on Design, automation and test in Europe (2007)

This paper introduces a class of single-ended coding schemes to reduce off-chip interconnect energy consumption. State-of-the-art codes for processor-memory off-chip interfaces require the transmitter and receiver (memory controller and memory) to collaborate using current and previously transmitted values to encode and decode data. Modern embedded systems, however, cannot afford to use such double-ended codes that require specialized memories to participate in the code. In contrast, a single-ended code enables the memory controller to encode data stored in memory and subsequently decode that data when it is retrieved, allowing the use of commodity memories. In this paper, single-ended codes are presented that assign limited-weight codewords using trace-based mapping techniques. Simulation results show that such codes can reduce the energy consumption of an uncoded off-chip interconnect by up to 42.5%.
The true duration of the impulse response used to estimate reverberation time
Authors: L. Faiget
Venue: Proceedings of the Acoustics, Speech, and Signal Processing, 1996. on Conference Proceedings., 1996 IEEE International Conference - Volume 02 (1996)

Since Schroeder [1965], reverberation time can be computed from the impulse response. Some other studies have shown the advantages of this method leading often to more accurate results than the classical ones. But, it can be shown that, when background noise is an important energetic part of the impulse response, Schroeder's method must be revised. A theoretical approach is proposed showing the influence of background noise and the integration boundaries in Schroeder's equation. Hence, a new upper limit of integration is defined based on regression lines to model background noise and decay. The intersection defines t' being the useful length of the impulse response. Experiments were processed in a large factory hall. Comparisons between classical reverberation time measurements and Schroeder's method are made showing good results even for the lowest values of signal-to-noise ratio.
Scaling multiplayer online games using proxy-server replication: a case study of Quake 2
Authors: Jens Müller, Sergei Gorlatch, Tobias Schröter, Stefan Fischer
Venue: Proceedings of the 16th international symposium on High performance distributed computing (2007)

Massively Multiplayer Online Games (MMOGs) are an increasingly popular class of real-time interactive distributed applications that require scalable architectures and parallelization approaches. While games of the role-playing genre already allow thousands of users to concurrently participate in a single game session, there are important genres, in particular action and strategy games, which have not been scaled to the massively multiplayer realm so far. These games have hard requirements in terms of scalability, in particular regarding density: many players tend to congregate in small locations. In this paper, we outline our novel approach of replication-based parallelisation for scaling the density of players. The practical impact of our work is demonstrated by porting the popular action game QFusion, based on the famous Quake 2, onto our proxy-server system architecture using the replication approach. The experiments with the ported QFusion demonstrate its high responsiveness and show that our approach allows to almost triple the maximum number of simultaneous players on four servers as compared with a single-server version.
Integrating computing resources in the College of Engineering
Authors: N. LaTourrette
Venue: Proceedings of the Frontiers in Education Conference, 2001. 31st Annual - Volume 02 (2001)

Computing resources are a necessity for course work in all engineering disciplines. Some departments respond to these needs by creating small departmental computing laboratories with little collaboration, significant overlap in software and hardware, and ineffective use of space. Combining computing resources for a college can transform a decentralized, disconnected group of computers and laboratories into a centralized, unified computing environment. This could result in greater access, increased software availability, and better equipment. In this paper, the authors report on a transition to an integrated computing center and on the design and layout of such a facility. They discuss the hardware and software resources of a multi-platform, multi-discipline computing environment. Advantages and disadvantages of a centralized computing facility are addressed. The pros and cons are presented from the different viewpoints of the lab's constituents: academic administrators, faculty, students, and facility staff.
Neuronal selectivity, population sparseness, and ergodicity in the inferior temporal visual cortex
Authors: Leonardo Franco, Edmund T. Rolls, Nikolaos C. Aggelopoulos, Jose M. Jerez
Venue: Biological Cybernetics (2007)

The sparseness of the encoding of stimuli by single neurons and by populations of neurons is fundamental to understanding the efficiency and capacity of representations in the brain, and was addressed as follows. The selectivity and sparseness of firing to visual stimuli of single neurons in the primate inferior temporal visual cortex were measured to a set of 20 visual stimuli including objects and faces in macaques performing a visual fixation task. Neurons were analysed with significantly different responses to the stimuli. The firing rate distribution of 36% of the neurons was exponential. Twenty-nine percent of the neurons had too few low rates to be fitted by an exponential distribution, and were fitted by a gamma distribution. Interestingly, the raw firing rate distribution taken across all neurons fitted an exponential distribution very closely. The sparseness a s or selectivity of the representation of the set of 20 stimuli provided by each of these neurons (which takes a maximal value of 1.0) had an average across all neurons of 0.77, indicating a rather distributed representation. The sparseness of the representation of a given stimulus by the whole population of neurons, the population sparseness a p, also had an average value of 0.77. The similarity of the average single neuron selectivity a s and population sparseness for any one stimulus taken at any one time a p shows that the representation is weakly ergodic. For this to occur, the different neurons must have uncorrelated tuning profiles to the set of stimuli.
Goal-directed evaluation for the improvement of optical music recognition on early music prints
Authors: Laurent Pugin, John Ashley Burgoyne, Ichiro Fujinaga
Venue: Proceedings of the 7th ACM/IEEE-CS joint conference on Digital libraries (2007)

Optical music recognition (OMR) systems are promising tools for the creation of searchable digital music libraries. Using an adaptive OMR system for early music prints based on hidden Markov models, we leverage an edit distance evaluation metric to improve recognition accuracy. Baseline results are computed with new labeled training and test sets drawn from a diverse group of prints. We present two experiments based on this evaluation technique. The first resulted in a significant improvement to the feature extraction function for these images. The second is a goal-directed comparison of several popular adaptive binarization algorithms, which are often evaluated only subjectively. Accuracy increased by as much as 55% for some pages, and the experiments suggest several avenues for further research.
Interactive Digital Entertainment, Social Computing, and Lifestyle Computing
Authors: Paul Benjamin Lowry, Scott McCoy
Venue: Proceedings of the 40th Annual Hawaii International Conference on System Sciences (2007)

Some of the most dramatic recent developments in computing have been the explosive growth in interactive digital entertainment (IDE), and social and lifestyle computing--or the non-business use of computing for purposes of entertainment, socialization, and lifestyle augmentation. For example, the market for gaming alone is currently about $7.3 billion dollars, with $936 million in online gaming. Meanwhile, the market for digital entertainment in homes and home automation has reached an all-time high in 2005 with no end in sight. These non-business uses of computing represent large and legitimate markets with social implications that are so profound and global in impact that effected societies will never be the same.