ppxscal/embedding_network huggingface dataset:
A Real-Time Primary-Backup Replication Service
Authors: Hengming Zou, Farnam Jahanian
Venue: IEEE Transactions on Parallel and Distributed Systems (1999)

This paper presents a real-time primary-backup replication scheme to support fault-tolerant data access in a real-time environment. The main features of the system are fast response to client requests, bounded inconsistency between primary and backup, temporal consistency guarantee for replicated data, and quick recovery from failures. The paper defines external and interobject temporal consistency, the notion of phase variance, and builds a computation model that ensures such consistencies for replicated data deterministically where the underlying communication mechanism provides deterministic message delivery semantics and probabilistically where no such support is available. It also presents an optimization of the system and an analysis of the failover process which includes failover consistency and failure recovery time. An implementation of the proposed scheme is built within the $x$-kernel architecture on the MK 7.2 microkernel from the Open Group. The results of a detailed performance evaluation of this implementation are also discussed.
A Method to Detect and Characterize Ellipses Using the Hough Transform
Authors: Nick Bennett, Robert Burridge, Naoki Salto
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1999)

Web Extra:Download software mentionedinarticleIn this paper we describe a new technique for detecting and characterizing ellipsoidal shapes automatically from any type of image. This technique is a single pass algorithm which can extract any group of ellipse parameters or characteristics which can be computed from those parameters without having to detect all five parameters for each ellipsoidal shape. Moreover, the method can explicitly incorporate any a priori knowledge the user may have concerning ellipse parameters. The method is based on techniques from Projective Geometry and on the Hough Transform. This technique can significantly reduce interpretation and computation time by automatically extracting only those features or geometric parameters of interest from images and making exact use of a priori information.
Time-dependent visual adaptation for fast realistic image display
Authors: Sumanta N. Pattanaik, Jack Tumblin, Hector Yee, Donald P. Greenberg
Venue: Proceedings of the 27th annual conference on Computer graphics and interactive techniques (2000)

Human vision takes time to adapt to large changes in scene intensity, and these transient adjustments have a profound effect on visual appearance. This paper offers a new operator to include these appearance changes in animations or interactive real-time simulations, and to match a user's visual responses to those the user would experience in a real-world scene. Large, abrupt changes in scene intensities can cause dramatic compression of visual responses, followed by a gradual recovery of normal vision. Asymmetric mechanisms govern these time-dependent adjustments, and offer adaptation to increased light that is much more rapid than adjustment to darkness. We derive a new tone reproduction operator that simulates these mechanisms. The operator accepts a stream of scene intensity frames and creates a stream of color display images. All operator components are derived from published quantitative measurements from physiology, psychophysics, color science, and photography. ept intentionally simple to allow fast computation, the operator is meant for use with real-time walk-through renderings, high dynamic range video cameras, and other interactive applications. We demonstrate its performance on both synthetically generated and acquired &ldquo;real-world&rdquo; scenes with large dynamic variations of illumination and contrast.
Toward an Efficient Parallel Eigensolver for Dense Symmetric Matrices
Authors: Bruce Hendrickson, Elizabeth Jessup, Christopher Smith
Venue: SIAM Journal on Scientific Computing (1999)

We describe a parallel algorithm for finding the eigenvalues and eigenvectors of a dense symmetric matrix, with an emphasis on the dense linear algebra operations. We follow the traditional three-step process: reduce to tridiagonal form, solve the tridiagonal problem, then backtransform the result. Since the different steps have different algorithmic characteristics, this problem serves as a perfect vehicle for exploring some issues associated with parallel linear algebra calculations. In particular, we examine the effects of matrix distribution and blocking on the computational performance of tridiagonalization and backtransformation. Through experiments on an Intel Paragon, we demonstrate that block storage of the matrix is not necessary for a highly efficient block algorithm. The performance of our approach compares very favorably with that of the corresponding ScaLAPACK routines.
Multithreaded algorithms for the fast Fourier transform
Authors: Parimala Thulasiraman, Kevin B. Theobald, Ashfaq A. Khokhar, Guang R. Gao
Venue: Proceedings of the twelfth annual ACM symposium on Parallel algorithms and architectures (2000)

In this paper we present fine-grained multithreaded algorithms and implementations for the Fast Fourier Transform (FFT) problem. The FFT problem has been formulated using two distinct approaches based on the dataflow concepts. The first approach, referred to as the receiver-initiated algorithm, realizes the FFAT iterations as a parent-child relationship while fully exploiting the underlying parallelism. The second approach, referred to as the sender-initiated algorithm, follows a data-flow model based on the producer-consumer style of programming and can be adopted to different architectural parameters for achieving high performance. The implementations of the proposed algorithms have been carried out on the EARTH (Efficient Architecture for Running THreads) platform. For both the algorithms, we analyze the ratio of remote vs local threads and study its impact on the experimental results. Our implementation results show that for certain block sizes on fixed problem size and machine size, the receiver-initiated approach performs better than the sender-initiated approach. For large number of processors, both the algorithms perform well, yielding execution times of only 10 msec for an input of 16 K data points on a 64 processor machine, assuming each processor running at 140 MHz clock speed.
The specification and enforcement of authorization constraints in workflow management systems
Authors: Elisa Bertino, Elena Ferrari, Vijay Atluri
Venue: ACM Transactions on Information and System Security (TISSEC) (1999)

In recent years, workflow management systems (WFMSs) have gained popularity in both research and commercial sectors. WFMSs are used to coordinate and streamline business processes. Very large WFMSs are often used in organizations with users in the range of several thousands and process instances in the range of tens and thousands. To simplify the complexity of security administration, it is common practice in many businesses to allocate a role for each activity in the process and then assign one or more users to each role&mdash;granting an authorization to roles rather than to users. Typically, security policies are expressed as constraints (or rules) on users and roles; separation of duties is a well-known constraint. Unfortunately, current role-based access control models are not adequate to model such constraints. To address this issue we (1) present a language to express both static and dynamic authorization constraints as clauses in a logic program; (2) provide formal notions of constraint consistency; and (3) propose algorithms to check the consistency of constraints and assign users and roles to tasks that constitute the workflow in such a way that no constraints are violated.
NotePals: lightweight note sharing by the group, for the group
Authors: Richard C. Davis, James A. Landay, Victor Chen, Jonathan Huang, Rebecca B. Lee, Frances C. Li, James Lin, Charles B. Morrey,  III, Ben Schleimer, Morgan N. Price, Bill N. Schilit
Venue: Proceedings of the SIGCHI conference on Human factors in computing systems: the CHI is the limit (1999)

NotePals is a lightweight note sharing system that gives group members easy access to each others experiences through their personal notes. The system allows notes taken by group members in any context to be uploaded to a shared repository. Group members view these notes with browsers that allow them to retrieve all notes taken in a given context or to access notes from other related notes or documents. This is possible because NotePals records the context in which each note is created (e.g., its author, subject, and creation time). The system is lightweight because it fits easily into group members regular note- taking practices, and uses informal, ink-based user interfaces that run on portable, inexpensive hardware. In this paper we describe NotePals, show how we have used it to share our notes, and present our evaluations of the system.
Analysis of the cost-effectiveness of information networks with applications
Authors: Rafiq Jamal-Aldeen, Saad Haj Bakry, Adnan Haj Nouh
Venue: International Journal of Network Management (2000)

This paper presents a methodology for the analysis of the cost-effectiveness of information networks over a period of time. The cost-effectiveness is considered to be associated with use-dependent and use-independent costs and benefits. Copyright &copy; 2000 John Wiley Sons, Ltd.
A relations-based approach for simplifying metrices extraction
Authors: Giancarlo Succi, Eric Liu
Venue: ACM SIGAPP Applied Computing Review (1999)

The field of software metrics is constantly changing and metrics extraction tools have to be updated frequently to handle these changes. This paper details the use of an intermediate relation set to decouple code parsing from metrics analysis. Parsers simply generate a set of intuitive relations, which a separate analyzer uses as input to compute arbitrary metrics. Then, new metrics simply have to be specified in terms of these relations. A C++ metrics extractor tool for OO design metrics was built as a proof of concept.
On the Minimum Problem for a Class of Noncoercive Nonconvex Functionals
Authors: Graziano Crasta
Venue: SIAM Journal on Control and Optimization (1999)

We are concerned with the problem of existence of solutions to the variational problem \[ \min\left\{\int_0^R g(t,v'(t))\,dt;\ v\in AC([0,R]),\ v(R)=0\right\}, \] with only one fixed endpoint prescribed. The map $g\colon [0,R]\times\mathbb{R}\to\overline{\mathbb{R}}$ is a normal integrand, for which neither convexity nor superlinear growth conditions are assumed.As an application, we give an existence result for the radially symmetric variational problem \[ \min_{u\in\Wuu(B_R)}\int_{B_R} [{f\pt{\mod{x},\mod{\nabla u(x)}}+a(|x|)\,u(x)}]\,dx, \] where $B_R$ is the ball of $\mathbb{R}^n$ centered at the origin and with radius $R>0$, the map $f\colon [0,R]\times[0,+\infty[\to\overline{\mathbb{R}}$ is a normal integrand, and $a\in\L(0,R)$. Again, neither convexity nor superlinear growth conditions are made on f.These kinds of problems, with nonconvex Lagrangians with respect to $\nabla u$, arise in different fields of mathematical physics such as optimal design and nonlinear elasticity.
Localized watermarking: methodology and application to operation scheduling
Authors: Darko Kirovski, Miodrag Potkonjak
Venue: Proceedings of the 1999 IEEE/ACM international conference on Computer-aided design (1999)

This paper addresses the copyright protection problem of integrated circuits designed with blocks which are originated from multiple design sources. The process consists of two phases. First, a compact signature is generated from every block independently and made public. Utilizing such signatures, a design can be decomposed into its original building blocks, regardless of multiple hierarchies. Then, a map of all the blocks can be built, thus allowing to reconstruct the original copyright dependencies. The proposed methodology can be used by foundries to verify that designs submitted for fabrication contain blocks traceable to a legal source of intellectual property. The verification process is also useful to intellectual property providers and integrators, as it reduces the likelihood of infringement, thus ultimately minimizing the risk of litigation.
Histopathologic Variants of Basal Cell Carcinoma Correlation with Sex, Age and Localization
Authors: Neira Puizina-Ivić, Berezina Matoković, Ivo Glunčić, Siniša Maslovara, Jadranka Vela-Ljubić
Venue: Journal of Medical Systems (1999)

During the 6-year period (January 1,1993 to December 31, 1998) in the Laboratory for Dermatopathology of Department of Dermatovenereology in Clinical Hospital Split, 1616 basal cell carcinomas (BCC) of a total of 323 investigated specimens were diagnosed. The incident rate varies from 92 to 114 BCC per 100,000 inhabitans in the Split region. The sex ratio in material is 1,2:1 in favor of males. The frequence of BCC increases with the advanced age in both sexes with the peak in the age group from 70 to 79 years. The most frequent location in both sexes is the nose followed by cheeks and trunk. Statistic analysis showed a significantly higher occurrence of BCC in temporal region in the males and perioral region in the females&semi; respectively. The solid variant is the most frequent followed by superficial multicentric and solid-adenoid. Pure variants are found in 83.1% specimens, and mixed variants in 16.9%. Solid and adenoid variants are the most frequent on the nose and cheeks. According to statistics cystic variant is significantly higher on the forehead, and morpheic variant on the nose. Superficial multicentric variant is statisticaly more frequent on the trunk than on other locations. All specimens were reexamined and histopathologic variants were obtained. Over 2000 data are comprised which is a sufficient examination sample. In programs such as SPSS, and Graph master ver 1,12, Win95, MO'97 (Word, Excel, Access) on Pentium II 200 MHz, floppy, 64 MB RAM, HDD 2,1 GB, CD x24, HP LJet 6L, a comprehensive analysis has been performed.
An Interleaving Transformation for Parallelizing Reductions for Distributed-Memory Parallel Machines
Authors: Jan-Jan Wu
Venue: The Journal of Supercomputing (2000)

Reduction operations frequently appear in algorithms. Due to their mathematical invariance properties (assuming that round-off errorscan be tolerated), it is reasonable to ignore ordering constraints on the computation of reductions in order to take advantage of the computing power of parallel machines.One obvious and widely-used compilation approach for reductions is syntactic pattern recognition. Either the source language includes explicit reduction operators, or certain specific loops are recognized as equivalent to known reductions. Once such patterns are recognized, hand optimized code for the reductions are incorporated in the target program. The advantage of this approach is simplicity. However, it imposes restrictions on the reduction loops&mdash;no data dependence other than that caused by the reduction operation itself is allowed in the reduction loops.In this paper, we present a parallelizing technique, interleaving transformation, for distributed-memory parallel machines. This optimization exploits parallelism embodied in reduction loops through combination of data dependence analysis and region analysis. Data dependence analysis identifies the loop structures and the conditions that can trigger this optimization. Region analysis divides the iteration domain into a sequential region and an order-insensitive region. Parallelism is achieved by distributing the iterations in the order-insensitive region among multiple processors. We use a triangular solver as an example to illustrate the optimization. Experimental results on various distributed-memory parallel machines, including the Connection Machines CM-5, the nCUBE, the IBM SP-2, and a network of Sun Workstations are reported.
Linear and Nonlinear Image Deblurring: A Documented Study
Authors: Alfred S. Carasso
Venue: SIAM Journal on Numerical Analysis (1999)

Nonlinear image deblurring procedures based on probabilistic considerations are widely believed to outperform conventional linear methods. This paper is exclusively concerned with nonsmooth images such as those that occur in biomedical imaging, where reconstruction of high frequency detail is of prime interest, and where avoidance of a priori smoothness constraints is a major concern. The theoretical basis behind each of the following nonlinear procedures is examined: the Lucy--Richardson method, the maximum likelihood E-M algorithm, the Poisson maximum a posteriori method, and the Nu&ntilde;ez--Llacer version of the maximum entropy method. A linear iterative method, VanCittert's iteration, is also studied. It is shown that each of the first three methods, as well as VanCittert's method, lack a necessary ingredient for successful solution of the ill-posed deblurring problem, while in the maximum entropy method, the enforced smoothness may have adverse consequences in medical imaging. A direct linear method, the slow evolution from the continuation boundary (SECB) method, designed specifically for nonsmooth images, is also considered. That method is stabilized by constraining the blurring operator as well as the solution and does not require smoothness constraints. It is shown that useful error estimates can be obtained in the SECB method while this is impossible in Tikhonov's method without a priori bounds on derivatives of the unknown solution. Reconstruction experiments on low noise synthetic MRI data show that thousands of iterations are necessary to achieve sufficient resolution in the iterative procedures. However, the SECB method provides higher resolution at considerable savings in computer time. At high noise levels, the iterative algorithms are shown to diverge. At these same noise levels, the SECB method produces reconstructions comparable in quality to those that would be obtained in the iterative methods, were one able to terminate the divergent algorithm at that iteration which best approximates the true solution in the L1 norm.
X-ability: a theory of replication
Authors: Svend Frølund, Rachid Guerraoui
Venue: Proceedings of the nineteenth annual ACM symposium on Principles of distributed computing (2000)

Different replication mechanisms provide different solutions to the same basic problem. However, there is no precise specification of the problem itself, only of particular classes of solutions, such as active replication and primary-backup. Having a precise specification of the problem would help us better understand the space of possible solutions. We present a formal definition of the problem solved by replication in the form of a correctness criterion called x-ability (exactly-once ability). An x-able service has obligations to its environment and its clients. It must update its environment under exactly-once semantics. Furthermore, it must provide idempotent, non-blocking request processing and deliver consistent results to its clients. X-ability is a local property: replicated services can be specified and implemented independently, and later composed in the implementation of more complex replicated services.
Analytical macromodeling for high-level power estimation
Authors: Guiseppe Bernacchia, Marios C. Papaefthymiou
Venue: Proceedings of the 1999 IEEE/ACM international conference on Computer-aided design (1999)

This paper present a new macromodeling technique for high-level power estimation. Our technique is based on a parameterizable analytical model that relies exclusively on statistical information of the circuit's primary inputs. During estimation, the statistics of the required metrics are extracted from the input stream, and a power estimate is obtained by evaluating a model function that has been characterized in advance. Our model yields power estimates within seconds, because it does not rely on the statistics of the circuit's primary outputs and, consequently, does not perform any simulation during estimation. Moreover, it achieves better accuracy than previous macromodeling approaches by taking into account both spatial and temporal correlations in the input stream.In experiments with the ISCAS-85 combinational circuits, the average absolute relative error of our power macromodeling technique was at most 1.8%. The worst-case error was at most 12.8%. For a ripple-carry adder family, in comparison with power estimates that were obtained using Spice, the average absolute and worst-case errors of our model's estimates were at most 5.1% and 19.8%, respectively.In addition to power dissipation, our macromodeling technique can be used to estimate the statistics of a circuit's primary outputs with very low average errors. It is thus suitable for power estimation in core-based systems with pre-characterized blocks. Once the metrics of the primary inputs are known, the power dissipation of the entire system can be estimated by simply propagating this information through the blocks using their corresponding model functions.
Rebuttal to the NIST RBAC model proposal
Authors: Trent Jaeger, Jonathon E. Tidswell
Venue: Proceedings of the fifth ACM workshop on Role-based access control (2000)

In this abstract, we rebut the proposed RBAC unified reference model as defined by Sandhu, Ferriaolo, and Kuhn [4]. As a unified reference model, this proposal simply re-enforces some of the concepts that are fundamental to RBAC (i.e., roles, users, and permissions) without clarifying the more complex concepts. Also, the definitions of the concepts are too informal to drive any useful standards proposal. We suggest formalizing the base concepts, including the addition of role administration, and that more work is necessary for constraints to be useful.
A Constant-Factor Approximation Algorithm for the Geometric k-MST Problem in the Plane
Authors: Joseph S. B. Mitchell, Avrim Blum, Prasad Chalasani, Santosh Vempala
Venue: SIAM Journal on Computing (1999)

We show that any rectilinear polygonal subdivision in the plane can be converted into a "guillotine" subdivision whose length is at most twice that of the original subdivision. "Guillotine" subdivisions have a simple recursive structure that allows one to search for "optimal" such subdivisions in polynomial time, using dynamic programming. In particular, a consequence of our main theorem is a very simple proof that the k-MST problem in the plane has a constant-factor polynomial-time approximation algorithm: we obtain a factor of 2 (resp., 3) for the L1 metric, and a factor of $2\sqrt{2}$ (resp., 3.266) for the L2 (Euclidean) metric in the case in which Steiner points are allowed (resp., not allowed).
Any Circulant-Like Preconditioner for Multilevel Matrices Is Not Superlinear
Authors: S. Serra Capizzano, E. Tyrtyshnikov
Venue: SIAM Journal on Matrix Analysis and Applications (1999)

Superlinear preconditioners (those that provide a proper cluster at 1) are very important for the cg-like methods since they make these methods converge superlinearly. As is well known, for Toeplitz matrices generated by a continuous symbol, many circulant and circulant-like (related to different matrix algebras) preconditioners were proved to be superlinear. In contrast, for multilevel Toeplitz matrices there has been no proof of the superlinearity of any multilevel circulants. In this paper we show that such a proof is not possible since any multilevel circulant preconditioner is not superlinear, in the general case of multilevel Toeplitz matrices. Moreover, for matrices not necessarily Toeplitz, we present some general results proving that many popular structured preconditioners cannot be superlinear.