14456420
A replica control method for improving availability for read-only transactions
Data replication is often considered in distributed database systems to enhance availability and performance. The benefit of data replication, however can only be realized at the cost of maintaining the consistency of data. In particular, network partition failures make it more difficult to achieve high data availability while ensuring strong correctness criteria such as l-copy serializability. We propose a replica control method to improve the availability of data in the presence of network partition failures. Our method extends the traditional primary copy method by using the relaxed correctness criterion called insular consistency for large-scale distributed systems, where partition failures frequently occur. We focus on increasing the availability of data for read-only transactions. We introduce a version vector as a tool for guaranteeing insular consistency and present a mechanism that allows read-only transactions to be executed at any partition as long as the insular consistency is satisfied. An asynchronous update propagation mechanism is also employed to improve the performance of update operations. We also show that the proposed method is correct and give some performance considerations.
13362734
FINDIT: a fast and intelligent subspace clustering algorithm using dimension voting
Abstract The aim of this paper is to present a novel subspace clustering method named FINDIT. Clustering is the process of finding interesting patterns residing in the dataset by grouping similar data objects from dissimilar ones based on their dimensional values. Subspace clustering is a new area of clustering which achieves the clustering goal in high dimension by allowing clusters to be formed with their own correlated dimensions. In subspace clustering, selecting correct dimensions is very important because the distance between points is easily changed according to the selected dimensions. However, to select dimensions correctly is difficult, because data grouping and dimension selecting should be performed simultaneously. FINDIT determines the correlated dimensions for each cluster based on two key ideas: dimension-oriented distance measure which fully utilizes dimensional difference information, and dimension voting policy which determines important dimensions in a probabilistic way based on V nearest neighbors' information. Through various experiments on synthetic data, FINDIT is shown to be very successful in the high dimensional clustering problem. FINDIT satisfies most requirements for good clustering methods such as accuracy of results, robustness to the noise and the cluster density, and scalability to the dataset size and the dimensionality. Moreover, it is gracefully scalable to full dimension without any modification to algorithm.
850911
Usability-based caching of query results in OLAP systems
In this paper we propose a new cache management scheme for online analytical processing (OLAP) systems based on the usability of query results in rewriting and processing other queries. For effective admission and replacement of OLAP query results, we consider the benefit of query results not only for recently issued queries but for the expected future queries of a current query. We exploit semantic relationships between successive queries in an OLAP session, which are derived from the interactive and navigational nature of OLAP query workloads, in order to classify and predict subsequent future queries. We present a method for estimating the usability of query results for the representative future queries using a probability model for them. Experimental evaluation shows that our caching scheme using the past and future usability of query results can reduce the cost of processing OLAP query workloads effectively only with a small cache size and outperforms the previous caching strategies for OLAP systems.
37385528
A framework for handling dependencies among web services transactions
This paper proposes an effective Web services (WS) transaction management framework to automatically manage inconsistencies occurred by relaxing isolation of WS transactions.
591216
The HS File: A New Dynamic Signature File Method for Efficient Information Retrieval
Many works on the signature file methods have been made in the past, but they are mainly for static environments. However, many recent applications in practice require a dynamic information storage structure that effectively supports insertions, deletions and updates. Though there are a few signature file techiniques for dynamic environments, they suffer from serious performance degradation when query signature weights are light. In this paper, we propose a new dynamic signature file organization, called the hierarchical signature(HS) file, that solves the problem of light query signature weights. We perform simulation experiments by using wide range of parameter values. We show through performance comparison based on experiments that the HS file improves performance significantly in both the retrieval time and the storage over-head over the other dynamic signature file methods proposed earlier.
8831551
A per-object based hybrid concurrency control
Existing concurrency control algorithms do not conform well to various environments in the performance perspective. Each algorithm has some assumption on the conflict characteristic of its execution environment, and its performance degrades when the assumption fails. A per-object hybrid scheme integrating a two phase locking algorithm with a parallel validation technique is presented to solve this problem. Read and write accesses on each database object are controlled by one algorithm at a time. This controlling algorithm can alter while transactions are running, in order to enhance the overall system performance. In the simulation study, the proposed scheme with the proposed algorithm alteration strategy is shown to conform well to various execution environments, better than both the two phase locking algorithm and the parallel validation technique.
10094158
System and software designs for transaction processing in asymmetric communication environments
Observing that it is impractical to use traditional methods to control concurrency in broadcast-based asymmetric communication environments, we introduce a concurrency control protocol designed for broadcast-based transaction processing called Server Timestamp and Update Broadcast Supported Concurrency (STUBcast). STUBcast supports two new correctness criteria proposed in this paper—Single Serializability and Local Serializability. These criteria are weaker than global serializability, but are practical and easier to achieve in broadcast environments. This article also discusses the software design for the simulation program and the protocol implementation. Simulation results collected using our simulation program suggest that STUBcast could be very efficient in realistic application environments. Copyright © 2003 John Wiley & Sons, Ltd.
9259468
Classification of Multiple Cancer Types by Multicategory Support Vector Machines Using Gene Expression Data
MOTIVATION
High-density DNA microarray measures the activities of several thousand genes simultaneously and the gene expression profiles have been used for the cancer classification recently. This new approach promises to give better therapeutic measurements to cancer patients by diagnosing cancer types with improved accuracy. The Support Vector Machine (SVM) is one of the classification methods successfully applied to the cancer diagnosis problems. However, its optimal extension to more than two classes was not obvious, which might impose limitations in its application to multiple tumor types. We briefly introduce the Multicategory SVM, which is a recently proposed extension of the binary SVM, and apply it to multiclass cancer diagnosis problems.


RESULTS
Its applicability is demonstrated on the leukemia data (Golub et al., 1999) and the small round blue cell tumors of childhood data (Khan et al., 2001). Comparable classification accuracy shown in the applications and its flexibility render the MSVM a viable alternative to other classification methods.


SUPPLEMENTARY INFORMATION
http://www.stat.ohio-state.edu/~yklee/msvm.htm
6621245
Application of Machine Shop Data Model in Manufacturing Simulation
Simulation technology holds tremendous promise for the manufacturing industry. A machine shop data model has been developed at the National Institute of Standards and Technology (NIST) to represent neutral machine shop data for supporting machine shop manufacturing simulation [1]. This paper discusses the data model and its application in manufacturing simulation. The paper also proposes an application framework that integrates the simulation model, machine shop database, and machine shop XML (Extensible Markup Language) data document. A prototype system is developed to present the application of machine shop data model using the proposed framework.
17285716
Voltage-clock-scaling adaptive scheduling techniques for low power in hard real-time systems
Many embedded systems operate under severe power and energy constraints. Voltage clock scaling is one mechanism by which energy consumption may be reduced; it is based on the fact that power consumption is a quadratic function of the voltage, while the speed is a linear function. The authors show how voltage scaling can be scheduled to reduce energy usage while still meeting real time deadlines.
13167655
Optimal Dynamic Control of Resources in a Distributed System
Abstrad-The various advantages of distributed systems can be reallzed unly when their resources are ‘*optimally” (in some sense) contrdled and utilI7~d. For example, distributed systems must he recnnfigured dynamically to rope with component failures and workload changts. Owing to the inherent dilkulty in formulating and solving re~iurce contrd problems, the resnurce control strategies currently propoacdlused for distributed systems are largely ad hoc. It is our purpose in this paper to I) quantitatively formulate the problem of controlling resources in a distributed system so as tu optimize a reward function, and 2) derive optimal control strategies using Markov decision theory. The control variables treated here are quite generak fnr example, they could be control decisions related to system configuration, repair, diagnostics, files, or data. Two algnrithms for resource contnfl In distributed systems are derived for time-invariant Bnd periodic environments, respectively. A detailed example to demonstrate the power and usefulness of our approach is provided.