ppxscal/embedding_network huggingface dataset:
Approximate computation of multidimensional aggregates of sparse data using wavelets
Authors: Jeffrey Scott Vitter, Min Wang
Venue: Proceedings of the 1999 ACM SIGMOD international conference on Management of data (1999)

Computing multidimensional aggregates in high dimensions is a performance bottleneck for many OLAP applications. Obtaining the exact answer to an aggregation query can be prohibitively expensive in terms of time and/or storage space in a data warehouse environment. It is advantageous to have fast, approximate answers to OLAP aggregation queries. In this paper, we present a novel method that provides approximate answers to high-dimensional OLAP aggregation queries in massive sparse data sets in a time-efficient and space-efficient manner. We construct a compact data cube, which is an approximate and space-efficient representation of the underlying multidimensional array, based upon a multiresolution wavelet decomposition. In the on-line phase, each aggregation query can generally be answered using the compact data cube in one I/O or a smalll number of I/Os, depending upon the desired accuracy. We present two I/O-efficient algorithms to construct the compact data cube for the important case of sparse high-dimensional arrays, which often arise in practice. The traditional histogram methods are infeasible for the massive high-dimensional data sets in OLAP applications. Previously developed wavelet techniques are efficient only for dense data. Our on-line query processing algorithm is very fast and capable of refining answers as the user demands more accuracy. Experiments on real data show that our method provides significantly more accurate results for typical OLAP aggregation queries than other efficient approximation techniques such as random sampling.
An 8mA, 3.8dB NF, 40dB gain CMOS front-end for GPS applications
Authors: F. Svelto, S. Deantoni, G. Montagna, R. Castello
Venue: Proceedings of the 2000 international symposium on Low power electronics and design (2000)

A fully differential 0.35&mgr;m CMOS LNA plus mixer, tailored to a double conversion architecture, for GPS applications has been realized. The LNA makes use of an inductively degenerated input stage and a resonant LC load, featuring 12% frequency tuning, accomplished by an MOS varactor. The mixer is a Gilbert cell like, in which an NMOS and a PMOS differential pair, shunted together, realize the input stage. This topology allows to save power, for given mixer gain and linearity. The front-end measured performances are: 40dB gain, 3.8dB NF, -25.5dBm IIP3, 1.3GHz input frequency, 140MHz output frequency, with 8mA from a 2.8V voltage supply.
An ATM-Based Connection Management Architecture forTelecommunications Services
Authors: Simon Znaty
Venue: Journal of Network and Systems Management (1999)

New open service architectures are now emerging. An important part of these architectures is the connection management function. It enables the establishment, control and release of semipermanent connections requested by telecommunications services such as virtual private networks. This paper presents the specification, design and implementation of this connection management function in our OAMS Open Service Architecture. The proposed architecture is deployed over a distributed processing environment.
Wattch: a framework for architectural-level power analysis and optimizations
Authors: David Brooks, Vivek Tiwari, Margaret Martonosi
Venue: ACM SIGARCH Computer Architecture News (2000)

Power dissipation and thermal issues are increasingly significant in modern processors. As a result, it is crucial that power/performance tradeoffs be made more visible to chip architects and even compiler writers, in addition to circuit designers. Most existing power analysis tools achieve high accuracy by calculating power estimates for designs only after layout or floorplanning are complete. In addition to being available only late in the design process, such tools are often quite slow, which compounds the difficulty of running them for a large space of design possibilities. This paper presents Wattch, a framework for analyzing and optimizing microprocessor power dissipation at the architecture-level. Wattch is 1000X or more faster than existing layout-level power tools, and yet maintains accuracy within 10% of their estimates as verified using industry tools on leading-edge designs. This paper presents several validations of Wattch's accuracy. In addition, we present three examples that demonstrate how architects or compiler writers might use Wattch to evaluate power consumption in their design process. We see Wattch as a complement to existing lower-level tools; it allows architects to explore and cull the design space early on, using faster, higher-level tools. It also opens up the field of power-efficient computing to a wider range of researchers by providing a power evaluation methodology within the portable and familiar SimpleScalar framework.
Reconciling top-down and bottom-up design approaches in RMM
Authors: Tomás Isakowitz, Arnold Kamis, Marios Koufaris
Venue: ACM SIGMIS Database (1998)

The proliferation of intranets and extranets as well as the vast expansion of the World Wide Web (WWW) and electronic commerce indicate the need for a structured hypermedia design methodology that will guide the design, development, and maintenance of large multimedia and hypermedia information systems and collaborative systems. The Relationship Management Methodology (RMM) is a well-known hypermedia design methodology. In this paper we provide an extension to it that enhances the design process. We present an iterative process of application design that incorporates the design of the entire application as well as its components. The process includes the design of an application diagram in a top-down fashion, the design of the components or building blocks using the construct of an m-slice, and the regeneration of the application diagram in a bottom-up fashion. An iterative comparison and refinement of the two versions of the application diagram ensure a better final application.
On achievable service differentiation with token bucket marking for TCP
Authors: Sambit Sahu, Philippe Nain, Christophe Diot, Victor Firoiu, Don Towsley
Venue: ACM SIGMETRICS Performance Evaluation Review (2000)

The Differentiated services (diffserv) architecture has been proposed as a scalable solution for providing service differentiation among flows without any per-flow buffer management inside the core of the network. It has been advocated that it is feasible to provide service differentiation among a set of flows by choosing an appropriate &ldquo;marking profile&rdquo; for each flow. In this paper, we examine (i) whether it is possible to provide service differentiation among a set of TCP flows by choosing appropriate marking profiles for each flow, (ii) under what circumstances, the marking profiles are able to influence the service that a TCP flow receives, and, (iii) how to choose a correct profile to achieve a given service level. We derive a simple, and yet accurate, analytical model for determining the achieved rate of a TCP flow when edge-routers use &ldquo;token bucket&rdquo; packet marking and core-routers use active queue management for preferential packet dropping. From our study, we observe three important results: (i) the achieved rate is not proportional to the assured rate, (ii) it is not always possible to achieve the assured rate and, (iii) there exist ranges of values of the achieved rate for which token bucket parameters have no influence. We find that it is not easy to regulate the service level achieved by a TCP flow by solely setting the profile parameters. In addition, we derive conditions that determine when the bucket size influences the achieved rate, and rates that can be achieved and those that cannot. Our study provides insight for choosing appropriate token bucket parameters for the achievable rates.
Towards data mining benchmarking: a test bed for performance study of frequent pattern mining
Authors: Jian Pei, Runying Mao, Kan Hu, Hua Zhu
Venue: ACM SIGMOD Record (2000)

Performance benchmarking has played an important role in the research and development in relational DBMS, object-relational DBMS, data warehouse systems, etc. We believe that benchmarking data mining algorithms is a long overdue task, and it will play an important role in the research and development of data mining systems as well.Frequent pattern mining forms a core component in mining associations, correlations, sequential patterns, partial periodicity, etc., which are of great potential value in applications. There have been a lot of methods proposed and developed for efficient frequent pattern mining in various kinds of databases, including transaction databases, time-series databases, etc. However, so far there is no serious performance benchmarking study of different frequent pattern mining methods.To facilitate an analytical comparison of different frequent mining methods, we have constructed an open test bed for performance study of a set of recently developed, popularly used methods for mining frequent patterns in transaction databases and mining sequential patterns in sequence databases, with different data characteristics. The testbed consists of the following components.A synthetic data generator, which can generate large sets of synthetic data in various kinds of data distributions. A few large data sets from real world applications will also be provided.A good set of typical frequent pattern mining methods, ranging from classical algorithms to recent studies. The method are grouped into three classes: frequent pattern mining, max-pattern mining, and sequential pattern mining. For frequent pattern mining, we will demonstrate Apriori, hashing, partitioning, sampling, TreeProjection, and FP-growth. For maximal pattern mining, we will demonstrate MaxMiner, TreeProjection, and FP-growth-max. For sequential pattern mining, we will demonstrate GSP and FreeSpan.A set of performance curves. These algorithms their running speeds, scalabilities, bottlenecks, and performance on different data distributions, will be compared and demonstrated upon request. Some performance curves from our pre-conference experimental evaluations will also be shown.An open testbed. Our goal is to construct an extensible test bed which integrates the above components and supports an open-ended testing service. Researchers can upload the object codes of their mining algorithms, and run them in the test bed using these data sets. The architecture is shown in Figure 1.This testbed is our first step towards benchmarking data mining algorithms. By doing so, performance of different algorithms can be reported consistently, on the same platform, and in the same environment. After the demo, we plan to make the testbed available on the WWW so that it may, hopefully, benefit further research and development of efficient data mining methods.
HCI and the 3C convergence
Authors: Helen M. Meng
Venue: ACM SIGCHI Bulletin (2000)

We attempt to explore the implications of the "3C convergence" (convergence of content, computers and communications) on the HCI research agenda. The interaction between humans and the 3C's is becoming a daily staple as we continue to witness powerful computers unite in a networked environment where wireline and wireless communications enjoy broadening bandwidths that permit the transmission of multimedia content. We draw illustrative examples from the Hong Kong environment related to the 3C convergence, and we present issues which we believe to be important for the research and development of a universal, useful and usable human-computer interface.
A 2-Approximation Algorithm for the Undirected Feedback Vertex Set Problem
Authors: Vineet Bafna, Piotr Berman, Toshihiro Fujito
Venue: SIAM Journal on Discrete Mathematics (1999)

A feedback vertex set of a graph is a subset of vertices that contains at least one vertex from every cycle in the graph. The problem considered is that of finding a minimum feedback vertex set given a weighted and undirected graph. We present a simple and efficient approximation algorithm with performance ratio of at most 2, improving previous best bounds for either weighted or unweighted cases of the problem. Any further improvement on this bound, matching the best constant factor known for the vertex cover problem, is deemed challenging.The approximation principle, underlying the algorithm, is based on a generalized form of the classical local ratio theorem, originally developed for approximation of the vertex cover problem, and a more flexible style of its application.
Non-keyboard QWERTY touch typing: a portable input interface for the mobile user
Authors: Mikael Goldstein, Robert Book, Gunilla Alsiö, Silvia Tessa
Venue: Proceedings of the SIGCHI conference on Human factors in computing systems: the CHI is the limit (1999)

Using traditional mobile input devices results in decreased effectiveness and efficiency. To improve usability issues a portable Non-Keyboard QWERTY touch-typing paradigm that supports the mobile touch-typing user is presented and investigated. It requires negligible training time. Pressure sensors strapped to the fingertips of gloves detect which finger is depressed. A language model based on lexical and syntactic knowledge transforms the depressed finger stroke sequence into real words and sentences. Different mobile input QWERTY paradigms (miniaturised, floating and Non-Keyboard) have been compared with full-size QWERTY. Among the mobile input paradigms, the Non-Keyboard fared significantly better, both regarding character error rate and subjective ratings.
Erratum: the Travelling Salesman and the Pq-Tree
Authors: Rainer E. Burkard, Vladimir G. Deineko, Gerhard J. Woeginger
Venue: Mathematics of Operations Research (1999)

Due to a printer's error, incorrect figures were published as part of this paper in Mathematics of Operations Research, Vol. 23, No. 3, August 1998, pp. 613-623. The paper is reprinted correctly below: Let D = (dij) be the n &#215; n distance matrix of a set of n cities {1, 2,...,n}, and let T be a PQ-tree with node degree bounded by d that represents a set &#928;(T) of permutations over {1, 2,...,n}. We show how to compute for D in O(2dn3) time the shortest travelling salesman tour contained in &#928;(T). Our algorithm may be interpreted as a common generalization of the well-known Held and Karp dynamic programming algorithm for the TSP and of the dynamic programming algorithm for finding the shortest pyramidal TSP tour. A consequence of our result is that the shortcutting phase of the "twice around the tree" heuristic for the Euclidean TSP can be optimally implemented in polynomial time. This contradicts a statement of Papadimitriou and Vazirani as published in 1984.
Using Generalized Cayley Transformations within an Inexact Rational Krylov Sequence Method
Authors: R. B. Lehoucq, Karl Meerbergen
Venue: SIAM Journal on Matrix Analysis and Applications (1999)

The rational Krylov sequence (RKS) method is a generalization of Arnoldi's method. It constructs an orthogonal reduction of a matrix pencil into an upper Hessenberg pencil. The RKS method is useful when the matrix pencil may be efficiently factored. This paper considers approximately solving the resulting linear systems with iterative methods. We show that a Cayley transformation leads to a more efficient and robust eigensolver than the usual shift-invert transformation when the linear systems are solved inexactly within the RKS method. A relationship with the recently introduced Jacobi--Davidson method is also established.
Approximate Semidefinite Matrices in a Linear Variety
Authors: Charles R. Johnson, Pablo Tarazaga
Venue: SIAM Journal on Matrix Analysis and Applications (1998)

We both characterize and give a convergent algorithm for finding a matrix in a linear variety of matrices that is nearest (in the Frobenius norm) to the positive semidefinite (PSD) matrices. Our motivation is from matrix completions, and in that setting our observations take an especially useful form that we use to bound, and sometimes give closed-form formulae for, the distance from the set of completions to the PSD matrices in terms only of specified data.
Distributed Schur Complement Techniques for General Sparse Linear Systems
Authors: Yousef Saad, Maria Sosonkina
Venue: SIAM Journal on Scientific Computing (1999)

This paper presents a few preconditioning techniques for solving general sparse linear systems on distributed memory environments. These techniques utilize the Schur complement system for deriving the preconditioning matrix in a number of ways. Two of these preconditioners consist of an approximate solution process for the global system, which exploits approximate LU factorizations for diagonal blocks of the Schur complement. Another preconditioner uses a sparse approximate-inverse technique to obtain certain local approximations of the Schur complement. Comparisons are reported for systems of varying difficulty.
Path lookahead: a data flow view of PDES models
Authors: Richard A. Meyer, Rajive L. Bargrodia
Venue: Proceedings of the thirteenth workshop on Parallel and distributed simulation (1999)

Architectural advances are making PDES more difficult. Processor speed improves much more quickly than interprocessor communication and memory. Lagging memory performance has a much greater impact on optimistic techniques, especially for large scale models, but conservative techniques require more small protocol messages and are therefore impacted by slow IPC. The performance of conservative PDES is heavily dependent on the lookahead available in the simulation model. Finding larger lookahead not only allows for increased parallelism, it also reduces the number of protocol messages required. In this paper, a global view of a PDES model as a set of data flows is presented. Using this view, the lookahead of the model can be optimized, resulting in a significant decrease in protocol messages, with only a marginal increase in computation, using realistic, detailed models as examples.
Innovations in Financial Services, Relationships, and Risk Sharing
Authors: Franklin Allen, Douglas Gale
Venue: Management Science (1999)

Relationships between intermediaries and their customers have become increasingly important in recent years. This paper argues that the need for costly ex ante information acquisition and analysis is a major barrier to the participation of investors and firms in sophisticated markets. Long-term relationships between intermediaries and their customers, in which intermediaries provide implicit insurance to customers, can be an effective substitute for costly ex ante investigation. In this way, intermediaries allow firms and investors to reap the benefits of financial markets. Relationships are easiest to sustain when the ongoing benefits to both parties are high. As a result, competition may lower the benefits that can be obtained from relationships.
Redundant Synchronization Elimination for DOACROSS Loops
Authors: Ding-Kai Chen, Pen-Chung Yew
Venue: IEEE Transactions on Parallel and Distributed Systems (1999)

Cross-iterations data dependences in DOACROSS loops require explicit data synchronizations to enforce them. However, the composite effect of some data synchronizations may cover the other dependences and make the enforcement of those covered dependences redundant. In this paper, we propose an efficient and general algorithm to identify redundant synchronizations in multiply nested DOACROSS loops which may have multiple statements and loop-exit control branches. Eliminating redundant sychronizations in DOACROSS loops allows more efficient execution of such loops. We also address the issues of enforcing data synchronizations in iterations near the boundary of the iteration space. Because some dependences may not exist in those boundary iterations, it adds complexity in determining the redundant synchronizations for those boundary iterations. The necessary and sufficient condition under which the synchronization is uniformly redundant is also studied. These results allow a parallelizing compiler to generate efficient data synchronization instructions for DOACROSS loops.
Wormhole Broadcast in Hypercubes
Authors: Shahram Latifi, Myung Hoon Lee, Pradip K. Srimani
Venue: The Journal of Supercomputing (2000)

We consider the problem of broadcasting a message in the n-cube, Q_n, equipped with wormhole switching. The communication model assumed is one-port, and the broadcasting scheme is path-based whereby, during broadcasting along a path by a node, all the nodes on that path will receive the message. The wormhole path length is m where <m&le;n, and thus this is a generalization of an earlier work which considered a path length of n. First, a method is proposed which is based on recursively partitioning the cube to subcubes of dimension m, and then calling the previously developed algorithm on such Q_&minus;m's concurrently (cube-based broadcast). The second method is based on the concept of Gray codes (GCs), and at every given step, it forms the Hamiltonian path of appropriate size as the broadcast path (GC-based broadcast). It is shown that the steps required in GC-based broadcast is fewer than or equal to those needed by cube-based broadcast. Furthermore, comparison of time complexity of GC-based broadcast to the lower bound reveals that this algorithm is near-optimal, and in fact optimal in many cases. This work improves on the best algorithm developed for path-based broadcast in one-port hypercube both in complexity and in simplicity.
Steady 3D Flow Configurations for the Horizontal Thermal Convection with Thermocapillary Effects
Authors: M. Giangi, D. Mansutti, G. Richelli
Venue: Journal of Scientific Computing (1999)

A vast literature exists on the Benard flow, the vertical thermal convection flow, but almost no result is known on the horizontal counterpart. On account of the wide range of applications in geophysics, astrophysics, metereology, and material science&semi; we think that the horizontal thermal convection flow deserves as much consideration as the Benard problem. The present study is the first step towards the description of the bifurcation pattern of the horizontal thermal convection flow. We present several flow configurations of an incompressible Navier-Stokes fluid contained in a 4 &times; 1 &times; 1 parallelepipedic box with open top and vertical transversal walls at different temperature. The flow induced by the buoyancy force and the thermocapillary effects at the fluid/air interface is numerically computed within the Boussinesq approximation. The velocity-vorticity formulation with a fully implicit finite difference method are implemented in a parallel computational code. The strong coupling of the discrete equations ensures the correct mass balance at each time step and provides true-transient numerical flows. For fluids at Prandtl number Pr &equals; 0.015 (semiconductors and liquid metals), we describe the changes in shape of the main vortex and the intensity of the speed of the flow versus variations of the Grashof number. In the case of absence of thermocapillary effects, we observe that as Gr increases, the flow exhibits more and more three-dimensional effects. When we add the thermocapillary effects, we observe an increase of the speed of the flow with the formation of a steep boundary layer around the liquid/air interface.