ppxscal/embedding_network huggingface dataset:
Modeling and Experiments of Untethered Quadrupedal Running with a Bounding Gait: The Scout II Robot
Authors: Ioannis Poulakakis, James Andrew Smith, Martin Buehler
Venue: International Journal of Robotics Research (2005)

In this paper we compare models and experiments involving Scout II, an untethered four-legged running robot with only one actuator per compliant leg. Scout II achieves dynamically stable running of up to 1.3 m s-1 on flat ground via a bounding gait. Energetics analysis reveals a highly efficient system with a specific resistance of only 1.4. The running controller requires no task-level or body-state feedback, and relies on the passive dynamics of the mechanical system. These results contribute to the increasing evidence that apparently complex dynamically dexterous tasks may be controlled via simple control laws. We discuss general modeling issues for dynamically stable legged robots. Two simulation models are compared with experimental data to test the validity of common simplifying assumptions. The need for including motor saturation and non-rigid torque transmission characteristics in simulation models is demonstrated. Similar issues are likely to be important in other dynamically stable legged robots as well. An extensive suite of experimental results documents the robot's performance and the validity of the proposed models.
Speed-accuracy tradeoff in Fitts' law tasks: on the equivalency of actual and nominal pointing precision
Authors: Shumin Zhai, Jing Kong, Xiangshi Ren
Venue: International Journal of Human-Computer Studies (2004)

Pointing tasks in human-computer interaction obey certain speed-accuracy tradeoff rules. In general, the more accurate the task to be accomplished, the longer it takes and vice versa. Fitts' law models the speed-accuracy tradeoff effect in pointing as imposed by the task parameters, through Fitts' index of difficulty (Id) based on the ratio of the nominal movement distance and the size of the target. Operating with different speed or accuracy biases, performers may utilize more or less area than the target specifies, introducing another subjective layer of speed-accuracy tradeoff relative to the task specification. A conventional approach to overcome the impact of the subjective layer of speed-accuracy tradeoff is to use the a posteriori "effective" pointing precision We in lieu of the nominal target width W. Such an approach has lacked a theoretical or empirical foundation. This study investigates the nature and the relationship of the two layers of speed-accuracy tradeoff by systematically controlling both Id and the index of target utilization Iu in a set of four experiments. Their results show that the impacts of the two layers of speed-accuracy tradeoff are not fundamentally equivalent. The use of We could indeed compensate for the difference in target utilization, but not completely. More logical Fitts' law parameter estimates can be obtained by the We adjustment, although its use also lowers the correlation between pointing time and the index of difficulty. The study also shows the complex interaction effect between Id and Iu, suggesting that a simple and complete model accommodating both layers of speed-accuracy tradeoff may not exist.
An HLLC Riemann solver for magneto-hydrodynamics
Authors: Shengtai Li
Venue: Journal of Computational Physics (2005)

This paper extends a class of approximate Riemann solvers devised by Harten, Lax and van Leer (HLL) for Euler equations of hydrodynamics to magneto-hydrodynamics (MHD) equations. In particular, we extend the two-state HLLC (HLL for contact wave) construction of Toro, Spruce and Speares to MHD equations. We derive a set of HLLC middle states that satisfies the conservation laws. Numerical examples are given to demonstrate that the new MHD-HLLC solver can achieve high numerical resolution, especially for resolving contact discontinuity. In addition, this new solver maintains a high computational efficiency when compared to Roe's approximate Riemann solver.
Optimal Point Correspondence through the Use of Rank Constraints
Authors: Ricardo Oliveira, Joao Costeira, Joao Xavier
Venue: Proceedings of the 2005 IEEE Computer Society Conference on Computer Vision and Pattern Recognition (CVPR'05) - Volume 2 - Volume 02 (2005)

We propose a solution to the n-frame correspondence problem under the factorization framework. During the matching process, our algorithm takes explicitly into account the geometrical constraints associated to the reconstruction process. To this end, a rank constraint is imposed on the measurement matrix. Since our method relies solely on geometric constraints, it is not dependent on corners as image features and can consequently match generic points (e.g. contours). Outlier rejection is integrated as a part of the actual matching process. In general the problem is formulated as combinatorial, but we develop a method which can provide a solution with a low computational complexity. Because of this, our algorithm is able to handle high-dimensional matching problems that are common in real-life applications.
Haptic Glyphs (Hlyphs) " Structured Haptic Objects for Haptic Visualization
Authors: Jonathan C. Roberts, Keith Franklin
Venue: Proceedings of the First Joint Eurohaptics Conference and Symposium on Haptic Interfaces for Virtual Environment and Teleoperator Systems (2005)

Haptic devices can be used to visualize information. As well as representing tangible surfaces and forces to enhance virtual training simulators for instance, haptic devices have been used to realize tactile versions of diagrams and visualizations (such as line graphs and bar charts). Such depictions enable blind or partial sighted users to perceive and understand information. However, there are multiple challenges when presenting information tactically: (1) it is difficult to understand a summary of the information, and (2) it is challenging to represent multivariate information through these haptic representations. In this paper we present how hlyphs (haptic versions of the graphical glyph) can be created, describe design guidelines, and detail how they can be used to represent both summaries and multivariate information.
A conversational interface for online shopping
Authors: Joyce Chai, Veronika Horvath, Nanda Kambhatla, Nicolas Nicolov, Margo Stys-Budzikowska
Venue: Proceedings of the first international conference on Human language technology research (2001)

We present a deployed, conversational dialog system that assists users in finding computers based on their usage patterns and constraints on specifications. We discuss findings from a market survey and two user studies. We compared our system to a directed dialog system and a menu driven navigation system. We found that the conversational interface reduced the average number of clicks by 63% and the average interaction time by 33% over a menu driven search system. The focus of our continuing work includes developing a dynamic, adaptive dialog management strategy, robustly handling user input and improving the user interface.
Building Impress and Powerpoint slides with LaTeX and Perl
Authors: Paul Barry
Venue: Linux Journal (2005)

Take advantage of Openoffice.org's well-documented file formats to create presentations as easily as a Web site.
Energy-Efficient Computations on FPGAs
Authors: Viktor K. Prasanna
Venue: The Journal of Supercomputing (2005)

Recently, energy dissipation for computations on FPGAs has become an important performance metric. In this paper, we summarize our recent efforts in developing an algorithm-level design methodology for optimizing the energy performance of FPGA based implementations. For kernels, our design methodology consists of four steps: domain selection, domain-specific energy modeling, domain-space exploration and low-level simulation. To achieve system-level energy-efficiency, we outline a design methodology that integrates the kernel-level design methodology. Both the design methodologies can be used to achieve not only energy-efficiency but also latency, area, and power efficiency. We consider signal processing kernels as illustrative examples and demonstrate energy and time efficient algorithms and implementations for these on FPGAs. Example energy performance optimization through algorithmic optimizations include the 29--51% improvement in energy performance for a matrix multiplication kernel, 57--78% improvement for a FFT kernel and the 10--60% improvement for a floating-point LU decomposition kernel over state-of-the-art implementations. Similarly, an improvement of 41 to 46% in energy performance was achieved by the system-level design approach over a greedy approach for a MVDR adaptive beamforming application. Finally we briefly describe a high-level tool for obtaining parameterized and energy-efficient designs on FPGAs.
Notes on burst mitigation for transport protocols
Authors: Mark Allman, Ethan Blanton
Venue: ACM SIGCOMM Computer Communication Review (2005)

In this note we explore the various causes of micro-bursting in TCP connections and also the behavior of several mitigations that have been suggested in the literature along with extensions we develop herein. This note methodically sketches the behavior of the mitigations and presents the tradeoffs of various schemes as a data point in the ongoing discussion about preventing bursting in transport protocols.
A UML Approach to the Generation of Test Sequences for Java-Based Concurrent Systems
Authors: Soon-Kyeong Kim, Luke Wildman, Roger Duke
Venue: Proceedings of the 2005 Australian conference on Software Engineering (2005)

Starting with a UML specification that captures the underlying functionality of some given Java-based concurrent system, we describe a systematic way to construct, from this specification, test sequences for validating an implementation of the system. The approach is to first extend the specification to create UML state machines that directly address those aspects of the system we wish to test. To be specific, the extended UML state machines can capture state information about the number of waiting threads or the number of threads blocked on a given object. Using the SAL model checker we can generate from the extended UML state machines sequences that cover all the various possibilities of events and states. These sequences can then be directly transformed into test sequences suitable for input into a testing tool such as ConAn. As an illustration, the methodology is applied to generate sequences for testing a Java implementation of the producer-consumer system.
Semantic similarity between search engine queries using temporal correlation
Authors: Steve Chien, Nicole Immorlica
Venue: Proceedings of the 14th international conference on World Wide Web (2005)

We investigate the idea of finding semantically related search engine queries based on their temporal correlation; in other words, we infer that two queries are related if their popularities behave similarly over time. To this end, we first define a new measure of the temporal correlation of two queries based on the correlation coefficient of their frequency functions. We then conduct extensive experiments using our measure on two massive query streams from the MSN search engine, revealing that this technique can discover a wide range of semantically similar queries. Finally, we develop a method of efficiently finding the highest correlated queries for a given input query using far less space and time than the naive approach, making real-time implementation possible.
An empirical study of fault localization for end-user programmers
Authors: Joseph R. Ruthruff, Margaret Burnett, Gregg Rothermel
Venue: Proceedings of the 27th international conference on Software engineering (2005)

End users develop more software than any other group of programmers, using software authoring devices such as e-mail filtering editors, by-demonstration macro builders, and spreadsheet environments. Despite this, there has been little research on finding ways to help these programmers with the dependability of their software. We have been addressing this problem in several ways, one of which includes supporting end-user debugging activities through fault localization techniques. This paper presents the results of an empirical study conducted in an end-user programming environment to examine the impact of two separate factors in fault localization techniques that affect technique effectiveness. Our results shed new insights into fault localization techniques for end-user programmers and the factors that affect them, with significant implications for the evaluation of those techniques.
Measuring DEA efficiency in internet companies
Authors: Carlos Serrano-Cinca, Yolanda Fuertes-Callén, Cecilio Mar-Molinero
Venue: Decision Support Systems (2005)

This paper uses Data Envelopment Analysis (DEA), a non-parametric approach to the estimation of production functions, in order to assess efficiency in dot corn firms. These firms have two objectives: to make an impact in the Internet and to obtain revenues from their activities. For this reason, the outputs have been two: unique visitors--a web metric--and revenues. DEA efficiencies have been obtained under various input/output combinations. A ranking of dot com firms in terms of relative efficiency has been obtained. A method based on multivariate analysis has been proven to be successful at showing the strengths and weaknesses of individual dot com firms. It is shown that there is a relationship between the type of e-business (e-tailers, search/portal, content/communities), and the way in which efficiency is obtained. The paper suggests a new approach to the problem of deciding which inputs and outputs the model should contain.
RAPTOR: introducing programming to non-majors with flowcharts
Authors: Martin C. Carlisle, Terry A. Wilson, Jeffrey W. Humphries, Steven M. Hadfield
Venue: Journal of Computing Sciences in Colleges (2004)

When students are learning to develop algorithms, they very often spend more time dealing with issues of syntax than solving the problem. Additionally, the textual nature of most programming environments works against the learning style of the majority of students. RAPTOR is a flowchart-based programming environment, designed specifically to help students visualize their algorithms and avoid syntactic baggage. RAPTOR programs are created visually and executed visually by tracing the execution through the flowchart. Required syntax is kept to a minimum. Students preferred using flowcharts to express their algorithms, and were more successful creating algorithms using RAPTOR than using a traditional language or writing flowcharts without RAPTOR.
Analyze Grid from the Perspective of a Computing System
Authors: Guoshun Hao, Shilong Ma, Haoming Guo, Xiaolong Wu, Mei Yang, Yingtao Jiang
Venue: Proceedings of the International Conference on Information Technology: Coding and Computing (ITCC'05) - Volume II - Volume 02 (2005)

This paper presents a service-based grid computing model which emphasizes that a grid is a special computing system. By comparing this model with the traditional computing system model, we analyze their similarities and differences, which is important for related grid study. The proposed model is very useful for future study in grid computing: it not only provides instructions for developing a grid system, but also provides a framework for the theoretical grid research.
iHITS: Extending HITS for Personal Interests Profiling
Authors: Ziming Zhuang
Venue: Proceedings of the 19th International Conference on Advanced Information Networking and Applications - Volume 2 (2005)

Ever since the boom of World Wide Web, profiling online users' interests has become an important task for content providers. The traditional approach involves manual entry of users' data, which requires intensive labor and time. Recent approaches utilize machine learning and clustering techniques to build the profiles, by analyzing the content of the Web pages visited by the users. Because such solutions rely heavily on the textual information, although they are capable of differentiating different topics of interests, it remains a difficult task to determine the users' different levels of interests in a given topic as well as gauge the shift of interests over time. In this paper, we propose iHITS, which is an extension to the HITS (Hypertext-Induced Topic Search) algorithm. The algorithm automatically determines a ranked list of userýs interests through link analysis on Web pages that the user visited. The visit pattern is obtained from the browsing history. We evaluate our approach by comparing automatically-generated interests profiles of the users with usersý manual entry to examine its accuracy and effectiveness. Our evaluation shows that the approach is promising and achieves satisfactory results. Our study introduces a novel approach to build a user-interests profiling systems with the capability to automatically capture and rank usersý browsing interests preference.
A Discontinuous Galerkin Method for Linear Symmetric Hyperbolic Systems in Inhomogeneous Media
Authors: Peter Monk, Gerard R. Richter
Venue: Journal of Scientific Computing (2005)

The Discontinuous Galerkin (DG) method provides a powerful tool for approximating hyperbolic problems. Here we derive a new space-time DG method for linear time dependent hyperbolic problems written as a symmetric system (including the wave equation and Maxwell's equations). The main features of the scheme are that it can handle inhomogeneous media, and can be time-stepped by solving a sequence of small linear systems resulting from applying the method on small collections of space-time elements. We show that the method is stable provided the space-time grid is appropriately constructed (this corresponds to the usual time-step restriction for explicit methods, but applied locally) and give an error analysis of the scheme. We also provide some simple numerical tests of the algorithm applied to the wave equation in two space dimensions (plus time).
Extending cubic uniform B-splines by unified trigonometric and hyperbolic basis
Authors: Jiwen Zhang, Frank-L. Krause
Venue: Graphical Models (2005)

In this paper, the trigonometric basis {sin t, cos t, t, 1} and the hyperbolic basis {sinh t, cosh t, t, 1} are unified by a shape parameter C (0 ≤ C < ∞). It yields the Functional B-splines (FB-splines) and its corresponding Subdivision B-splines (SB-splines). As well, a geometric proof of curvature continuity for SB-splines is provided. FB-splines and SB-splines inherited nearly all properties of B-splines, including the C2 continuity, and can represent elliptic and hyperbolic arcs exactly. They are adjustable, and each control point bi can have its unique shape parameter Ci. As Ci increases from 0 to ∞, the corresponding breakpoint of bi on the curve is moved to the location of bi, and the curvature of this breakpoint is increased from 0 to ∞ too. For a set of control points and their shape parameters, SB-spline and FB-spline have the same position, tangent, and curvature on each breakpoint. If two adjacent control points in the set have identical parameters, their SB-spline and FB-spline segments overlap. However, in general cases, FB-splines have no simple subdivision equation, and SB-splines have no common evaluation function. Furthermore, FB-splines and SB-splines can generate shape adjustable surfaces. They can represent the quadric surfaces precisely for engineering applications. However, the exact proof of C2 continuity for the general SB-spline surfaces has not been obtained yet.
Estimating 3D Shape and Texture Using Pixel Intensity, Edges, Specular Highlights, Texture Constraints and a Prior
Authors: Sami Romdhani, Thomas Vetter
Venue: Proceedings of the 2005 IEEE Computer Society Conference on Computer Vision and Pattern Recognition (CVPR'05) - Volume 2 - Volume 02 (2005)

We present a novel algorithm aiming to estimate the 3D shape, the texture of a human face, along with the 3D pose and the light direction from a single photograph by recovering the parameters of a 3D Morphable Model. Generally, the algorithms tackling the problem of 3D shape estimation from image data use only the pixels intensity as input to drive the estimation process. This was previously achieved using either a simple model, such as the Lambertian reflectance model, leading to a linear fitting algorithm. Alternatively, this problem was addressed using a more precise model and minimizing a non-convex cost function with many local minima. One way to reduce the local minima problem is to use a stochastic optimization algorithm. However, the convergence properties (such as the radius of convergence) of such algorithms, are limited. Here, as well as the pixel intensity, we use various image features such as the edges or the location of the specular highlights. The 3D shape, texture and imaging parameters are then estimated by maximizing the posterior of the parameters given these image features. The overall cost function obtained is smoother and, hence, a stochastic optimization algorithm is not needed to avoid the local minima problem. This leads to the Multi-Features Fitting algorithm that has a wider radius of convergence and a higher level of precision. This is shown on some example photographs, and on a recognition experiment performed on the CMU-PIE image database.
A framework for extending the synergy between MAC layer and query optimization in sensor networks
Authors: Vladimir I. Zadorozhny, Panos K. Chrysanthis, Prashant Krishnamurthy
Venue: Proceeedings of the 1st international workshop on Data management for sensor networks: in conjunction with VLDB 2004 (2004)

Queries in sensor networks are expected to produce results in a timely manner and for long periods, as needed. This implies that sensor queries need to be optimized with respect to both response time and energy consumption. With these requirements in mind, we develop novel cross-layer optimization techniques that utilize information about how the medium access control (MAC) layer operates while processing queries in large scale sensor network environments. The central framework of our approach is a Data Transmission Algebra that uniformly captures the structure of data transmissions along with their constraints and requirements. Our framework enables both qualitative analysis and quantitative cost-based optimization of sensor queries. We illustrate the effectiveness of our framework by developing a collision-aware scheduler and evaluating it experimentally.
Java: an eventful approach
Authors: Kim Bruce, Andrea Danyluk, Tom Murtagh
Venue: Journal of Computing Sciences in Colleges (2004)

As many have learned over the past several years, teaching a CS1 course in Java requires an entirely new approach. Because it is an object-oriented language, it is difficult to teach in the style used for imperative languages like Pascal, C, and even C++. Many have proposed teaching Java in an objects-first way, but others have complained that too many concepts must be introduced before students can understand the construction of classes and objects. The objective of this workshop is to introduce an approach to teaching Java that we have developed at Williams College that overcomes these problems. Our approach is supported by materials developed with NSF funding. These include extensive course notes, laboratory exercises, the Objectdraw library, and a textbook to be published in 2004.