bluuebunny/crossref_metadata_2025_split huggingface dataset:
Can ISPS and P2P users cooperate for improved performance?
Authors: Aggarwal Vinay , Feldmann Anja , Scheideler Christian 
Published: September 2007

Peer-to-peer (P2P) systems, which are realized as overlays on top of the underlying Internet routing architecture, contribute a significant portion of today's Internet traffic. While the P2P users are a good source of revenue for the Internet Service Providers (ISPs), the immense P2P traffic also poses a significant traffic engineering challenge to the ISPs. This is because P2P systems either implement their own routing in the overlay topology or may use a P2P routing underlay [1], both of which are largely independent of the Internet routing, and thus impedes the ISP's traffic engineering capabilities. On the other hand, P2P users are primarily interested in finding their desired content quickly, with good performance. But as the P2P system has no access to the underlying network, it either has to measure the path performance itself or build its overlay topology agnostic of the underlay. This situation is disadvantageous for both the ISPs and the P2P users.
To overcome this, we propose and evaluate the feasibility of a solution where the ISP offers an "oracle" to the P2P users. When the P2P user supplies the oracle with a list of possible P2P neighbors, the oracle ranks them according to certain criteria, like their proximity to the user or higher bandwidth links. This can be used by the P2P user to choose appropriate neighbors, and therefore improve its performance. The ISP can use this mechanism to better manage the immense P2P traffic, e.g., to keep it inside its network, or to direct it along a desired path. The improved network utilization will also enable the ISP to provide better service to its customers.
A type discipline for authorization policies
Authors: Fournet Cédric , Gordon Andrew D. , Maffeis Sergio 
Published: September 2007

Distributed systems and applications are often expected to enforce high-level authorization policies. To this end, the code for these systems relies on lower-level security mechanisms such as digital signatures, local ACLs, and encrypted communications. In principle, authorization specifications can be separated from code and carefully audited. Logic programs in particular can express policies in a simple, abstract manner.
We consider the problem of checking whether a distributed implementation based on communication channels and cryptography complies with a logical authorization policy. We formalize authorization policies and their connection to code by embedding logical predicates and claims within a process calculus. We formulate policy compliance operationally by composing a process model of the distributed system with an arbitrary opponent process. Moreover, we propose a dependent type system for verifying policy compliance of implementation code. Using Datalog as an authorization logic, we show how to type several examples using policies and present a general schema for compiling policies.
Experience distributing objects in an SMMP OS
Authors: Appavoo Jonathan , Silva Dilma Da , Krieger Orran , Auslander Marc , Ostrowski Michal , Rosenburg Bryan , Waterland Amos , Wisniewski Robert W. , Xenidis Jimi , Stumm Michael , Soares Livio 
Published: September 2007

Designing and implementing system software so that it scales well on shared-memory multiprocessors (SMMPs) has proven to be surprisingly challenging. To improve scalability, most designers to date have focused on concurrency by iteratively eliminating the need for locks and reducing lock contention. However, our experience indicates that locality is just as, if not more, important and that focusing on locality ultimately leads to a more scalable system.In this paper, we describe a methodology and a framework for constructing system software structured for locality, exploiting techniques similar to those used in distributed systems. Specifically, we found two techniques to be effective in improving scalability of SMMP operating systems: (i) an object-oriented structure that minimizes sharing by providing a natural mapping from independent requests to independent code paths and data structures, and (ii) the selective partitioning, distribution, and replication of object implementations in order to improve locality. We describe concrete examples of distributed objects and our experience implementing them. We demonstrate that the distributed implementations improve the scalability of operating-system-intensive parallel workloads.
XQuery layers
Authors: Braga Daniele , Campi Alessandro , Ceri Stefano , Spoletini Paola 
Published: September 2007

XML is becoming widespread as data interoperability standard in many application domains. An increasing number of researchers and professionals, who are not computer scientists (although they may have a strong technical background), needs to query and transform XML data during their working activities. Such tasks typically require simple queries and partial awareness of the XML data model, in the context of a given, domain-specific XML-based protocol.
The W3C community has proposed XQuery as the standard query language for XML [9]. XQuery has a huge expressive power - as it encompasses features belonging both to query and functional languages, but it may be considered as too complex for the above user profiles; well-designed subsets of XQuery are sufficient to satisfy their needs.
In this paper, we propose six layered subsets of XQuery, targeted to cover user communities with increasing needs. The initial layers are based upon XQBE (XQuery By Example), a visual XML query language, strictly less expressive than XQuery. We argue that the first layers are easier to learn and to master than the full language, also thanks to the availability of simple visual interfaces, and that these layers cover most of the needs of many user communities.
Image deblurring with blurred/noisy image pairs
Authors: Yuan Lu , Sun Jian , Quan Long , Shum Heung-Yeung 
Published: September 2007

Taking satisfactory photos under dim lighting conditions using a hand-held camera is challenging. If the camera is set to a long exposure time, the image is blurred due to camera shake. On the other hand, the image is dark and noisy if it is taken with a short exposure time but with a high camera gain. By combining information extracted from both blurred and noisy images, however, we show in this paper how to produce a high quality image that cannot be obtained by simply denoising the noisy image, or deblurring the blurred image alone.
Our approach is image deblurring with the help of the noisy image. First, both images are used to estimate an accurate blur kernel, which otherwise is difficult to obtain from a single blurred image. Second, and again using both images, a residual deconvolution is proposed to significantly reduce ringing artifacts inherent to image deconvolution. Third, the remaining ringing artifacts in smooth image regions are further suppressed by a gain-controlled deconvolution process. We demonstrate the effectiveness of our approach using a number of indoor and outdoor images taken by off-the-shelf hand-held cameras in poor lighting environments.
Line drawings via abstracted shading
Authors: Lee Yunjin , Markosian Lee , Lee Seungyong , Hughes John F. 
Published: September 2007

We describe a GPU-based algorithm for rendering a 3D model as a line drawing, based on the insight that a line drawing can be understood as an abstraction of a shaded image. We thus render lines along tone boundaries or thin dark areas in the shaded image. We extend this notion to the dual: we render highlight lines along thin bright areas and tone boundaries. We combine the lines with toon shading to capture broad regions of tone.
The resulting line drawings effectively convey both shape and material cues. The lines produced by the method can include silhouettes. creases, and ridges, along with a generalization of suggestive contours that responds to lighting as well as viewing changes. The method supports automatic level of abstraction, where the size of depicted shape features adjusts appropriately as the camera zooms in or out. Animated models can be rendered in real time because costly mesh curvature calculations are not needed.
Rotational symmetry field design on surfaces
Authors: Palacios Jonathan , Zhang Eugene 
Published: September 2007

Designing rotational symmetries on surfaces is a necessary task for a wide variety of graphics applications, such as surface parameterization and remeshing, painterly rendering and pen-and-ink sketching, and texture synthesis. In these applications, thetopologyof a rotational symmetry field such assingularitiesandseparatricescan have a direct impact on the quality of the results. In this paper, we present a design system that provides control over the topology of rotational symmetry fields on surfaces.As the foundation of our system, we provide comprehensive analysis for rotational symmetry fields on surfaces and present efficient algorithms to identify singularities and separatrices. We also describe design operations that allow a rotational symmetry field to be created and modified in an intuitive fashion by using the idea of basis fields and relaxation. In particular, we provide control over the topology of a rotational symmetry field by allowing the user to remove singularities from the field or to move them to more desirable locations.At the core of our analysis and design implementations is the observations thatN-way rotational symmetries can be described by symmetricN-th order tensors, which allows an efficient vector-based representation that not only supports coherent definitions of arithmetic operations on rotational symmetries but also enables many analysis and design operations for vector fields to be adapted to rotational symmetry fields.To demonstrate the effectiveness of our approach, we apply our design system to pen-and-ink sketching and geometry remeshing.
A theory of locally low dimensional light transport
Authors: Mahajan Dhruv , Shlizerman Ira Kemelmacher , Ramamoorthi Ravi , Belhumeur Peter 
Published: September 2007

Blockwise or Clustered Principal Component Analysis (CPCA) is commonly used to achieve real-time rendering of shadows and glossy reflections with precomputed radiance transfer (PRT). The vertices or pixels are partitioned into smaller coherent regions, and light transport in each region is approximated by alocally low-dimensional subspaceusing PCA. Many earlier techniques such as surface light field and reflectance field compression use a similar paradigm. However, there has been no clear theoretical understanding of how light transport dimensionality increases with local patch size, nor of the optimal block size or number of clusters.In this paper, we develop a theory of locally low dimensional light transport, by using Szego's eigenvalue theorem to analytically derive the eigenvalues of the covariance matrix for canonical cases. We show mathematically that for symmetric patches of areaA, the number of basis functions for glossy reflections increases linearly withA, while for simple cast shadows, it often increases as √A. These results are confirmed numerically on a number of test scenes. Next, we carry out an analysis of the cost of rendering, trading off local dimensionality and the number of patches, deriving an optimal block size. Based on this analysis, we provide useful practical insights for setting parameters in CPCA and also derive a new adaptive subdivision algorithm. Moreover, we show that rendering time scales sub-linearly with the resolution of the image, allowing for interactive all-frequency relighting of 1024 x 1024 images.
Key Point Subspace Acceleration and soft caching
Authors: Meyer Mark , Anderson John 
Published: September 2007

Many applications in Computer Graphics contain computationally expensive calculations. These calculations are often performed at many points to produce a full solution, even though the subspace of reasonable solutions may be of a relatively low dimension. The calculation of facial articulation and rendering of scenes with global illumination are two example applications that require these sort of computations. In this paper, we present Key Point Subspace Acceleration and Soft Caching, a technique for accelerating these types of computations.
Key Point Subspace Acceleration (KPSA) is a statistical acceleration scheme that uses examples to compute a statistical subspace and a set of characteristic key points. The full calculation is then computed only at these key points and these points are used to provide a subspace based estimate of the entire calculation. The soft caching process is an extension to the KPSA technique where the key points are also used to provide a confidence estimate for the KPSA result. In cases with high anticipated error the calculation will then "fail through" to a full evaluation of all points (a cache miss), while frames with low error can use the accelerated statistical evaluation (a cache hit).
The influence of shape on the perception of material reflectance
Authors: Vangorp Peter , Laurijssen Jurgen , Dutré Philip 
Published: September 2007

Visual observation is our principal source of information in determining the nature of objects, including shape, material or roughness. The physiological and cognitive processes that resolve visual input into an estimate of the material of an object are influenced by the illumination and the shape of the object. This affects our ability to select materials by observing them on a point-lit sphere, as is common in current 3D modeling applications.In this paper we present an exploratory psychophysical experiment to study various influences on material discrimination in a realistic setting. The resulting data set is analyzed using a wide range of statistical techniques. Analysis of variance is used to estimate the magnitude of the influence of geometry, and fitted psychometric functions produce significantly diverse material discrimination thresholds across different shapes and materials.Suggested improvements to traditional material pickers include direct visualization on the target object, environment illumination, and the use of discrimination thresholds as a step size for parameter adjustments.
From the chair
Authors: Sipior Janice C. , Lending Diane , Amoroso Donald L. , Shayo Conrad , Vowels Susan A. 
Published: September 2007

Welcome to the new academic year! I hope you had an enjoyable summer.
Please join me in congratulating the members of the ACM-SIGMIS CPR (Computer Personnel Research) 2007 Conference Committee for organizing a successful conference. This year's conference was held at the Hyatt Regency in St. Louis, Missouri, USA from April 19 - 21, 2007, http://www.sigmis.org/conferences.html. The SIGMIS CPR 2007 Conference Proceedings are available in the ACM Digital Library at: http://portal.acm.org/dl.cfm.

I would like to thank the members of the 2007 Conference Committee for all their hard work in making this conference a success:

Conference Co-Chairs:
Fred Niederman, St. Louis University Mary Sumner, Southern Illinois University Edwardsville

Program Co-Chairs:
Diane Lending, James Madison University Chelley Vician, Michigan Tech University

Local Arrangements:
Jo Ellen Moore, Southern Illinois University Edwardsville Susan Yager, Southern Illinois University Edwardsville

Treasurer:
Donald Amoroso, Appalachian State University

Publicity:
Anne Powell, Southern Illinois University Edwardsville Sandra Newton, University of South Florida

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The recipients of the fourth annual Magid Igbaria Outstanding Conference Paper of the Year Award are Tim Klaus of Texas A&M University, Stephen Wingreen of Southeastern University, and J. Ellis Blanton of University of South Florida for their paper, "Examining User Resistance and Management Strategies in Enterprise Systems Implementations." Congratulations to all of you!.
Please consider submitting your research to next year's CPR 2008. The submission deadline is October 15, 2007. Everyone is welcome! For information about next year's CPR 2008 Conference, please check our website at: http://www.acm.org/sigmis.
Also, please continue to consider Data Base as an outlet for your research. The new online submission system is available at the Data Base website at: http://the-database.org.

Finally, please mark your calendar now for the Seventh Annual ACM-SIGMIS Reception:

Where:
International Conference on Information Systems (ICIS2007) Fairmont The Queen Elizabeth Hotel, Montreal, Canada

When:
5:30 to 7:00 pm -- Saturday, December 8, 2007

Who:
All ACM-SIGMIS members and their invited guests are welcome!

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We appreciate your continued support of SIGMIS. We welcome any ideas or suggestions to improve SIGMIS. Please feel free to contact any one of us.
Future IS research in net-enabled organizations
Authors: Watson Richard T. , Straub Detmar W. 
Published: September 2007

This essay explores the interplay of network technology and the stakeholder viewpoint to argue that the information systems (IS) discipline is now in its third era of networking, and rapidly moving toward a fourth era. The first era, sans significant networks, concentrated on increasing employee productivity. The introduction of private networks ushered in a second era and brought in interorganizational systems that permitted interaction between and among businesses and governments. The third era is built on public networks, which enable firms to interact electronically with individual customers and investors, and to interact in new ways with governments. The fourth era, yet to arrive, will be built on high functionality, mobile devices that support real-time access and stakeholder locatability. Each era results in an order of magnitude increase in the potential impact of information systems on organizational performance because it can address the objectives of one or more additional groups of stakeholders.
Net-enabled organizations (NEOs) are the key evolutionary development of the third era. These organizations require insights into how to organize, architect, and implement the entire range of their electronic connections in the next several decades, and IS researchers are uniquely positioned to deliver on this vision.
The mechanics of in-kernel synchronization for a scalable microkernel
Authors: Uhlig Volkmar 
Published: September 2007

Systems with minimal kernels address the problem of ever-increasing system software complexity by strict separation of resource permission management and resource policies into different trust domains. Lately, such system structure has found wide attention in the research community and industry in the form of hypervisors and virtual machines.
With an increasing number of processors, these systems face a scalability problem. The separation eliminates semantic information about the expected parallelism for individual resources, such as memory pages or processors. Hence, the kernel is unable to optimize its synchronization primitives on a case-by-case basis---a precondition for a scalable, yet well-performing system.
In this paper we present an adaptive synchronization scheme, one of the core building block for scalable microkernels. Herewith, unprivileged components (like virtual machines) can express the degree of concurrency at the granularity of individual resources. The kernel can safely adapt and optimize its internal synchronization regime on a case-by-case basis as we show exemplary for inter-process communication and the memory management subsystem of an L4 microkernel.
Ethane
Authors: Casado Martin , Freedman Michael J. , Pettit Justin , Luo Jianying , McKeown Nick , Shenker Scott 
Published: September 2007

This paper presents Ethane, a new network architecture for the enterprise. Ethane allows managers to define a single network-wide fine-grain policy, and then enforces it directly. Ethane couples extremely simple flow-based Ethernet switches with a centralized controller that manages the admittance and routing of flows. While radical, this design is backwards-compatible with existing hosts and switches.
We have implemented Ethane in both hardware and software, supporting both wired and wireless hosts. Our operational Ethane network has supported over 300 hosts for the past four months in a large university network, and this deployment experience has significantly affected Ethane's design.
Reconciling performance and programmability in networking systems
Authors: Mudigonda Jayaram , Vin Harrick M. , Keckler Stephen W. 
Published: September 2007

Challenges in addressing the memory bottleneck have made it difficult to design a packet processing platform that simultaneously achieves both ease-of-programming and high performance. Today's commercial processors support two architectural mechanisms - namely, hardware multithreading and caching - to overcome the memory bottleneck. The configurations of these mechanisms (e.g., cache capacity, number of threads per processor core) are fixed at processor-design time. The relative effectiveness of these mechanisms, however, varies significantly with application, traffic, and system characteristics. Thus, programmers often struggle to achieve high performance from a processor that is not well-suited to a particular deployment.
To address this challenge, we first make a case for, and then develop a malleable processor architecture that facilitates the dynamic reconfiguration of cache capacity and number of threads to best-suit the needs of each deployment. We then present an algorithm that can determine the optimal thread-cache balance at run-time. The combination of these two allows us to simultaneously achieve the goals of ease-of-programming and high performance. We demonstrate that our processor outperforms a processor similar to Intel's IXP2800 - a state-of-the-art commercial Network Processor - in about 89% of the deployments we consider. Further, in about 30% of the deployments our platform improves the throughput by as much as 300%.
Can internet video-on-demand be profitable?
Authors: Huang Cheng , Li Jin , Ross Keith W. 
Published: September 2007

Video-on-demand in the Internet has become an immensely popular service in recent years. But due to its high bandwidth requirements and popularity, it is also a costly service to provide. We consider the design and potential benefits of peer-assisted video-on-demand, in which participating peers assist the server in delivering VoD content. The assistance is done in such a way that it provides the same user quality experience as pure client-server distribution. We focus on the single-video approach, whereby a peer only redistributes a video that it is currently watching.
Using a nine-month trace from a client-server VoD deployment for MSN Video, we assess what the 95 percentile server bandwidth costs would have been if a peer-assisted employment had been instead used. We show that peer-assistance can dramatically reduce server bandwidth costs, particularly if peers prefetch content when there is spare upload capacity in the system. We consider the impact of peer-assisted VoD on the cross-traffic among ISPs. Although this traffic is significant, if care is taken to localize the P2P traffic within the ISPs, we can eliminate the ISP cross traffic while still achieving important reductions in server bandwidth. We also develop a simple analytical model which captures many of the critical features of peer-assisted VoD, including its operational modes.