9854601
An effective recovery under fuzzy checkpointing in main memory databases
Abstract In main memory databases, fuzzy checkpointing gives less transaction overhead due to its asynchronous backup feature. However, till now, fuzzy checkpointing has considered only physical logging schemes. The size of the physical log records is very large, and hence it incurs space and recovery processing overhead. In this paper, we propose a recovery method based on a hybrid logging scheme, which permits logical logging under fuzzy checkpointing. The proposed method significantly reduces the size of log data, and hence offers faster recovery processing than other conventional fuzzy checkpointing with physical logging.
38239153
Qualitative Behavior Modeling of Information Processing Components
This paper presents qualitative behavior modeling of Information Processing Components(IPCs), which are domain-specific software components for modeling reusable functions in database management systems(DBMSs). After introducing a detailed formal syntax of IPCs, we propose their modular, qualitative behavior generation mechanism. The proposed mechanism is based on qualitative modeling and simulation, thus produces a sequence of temporal state transitions of modeled IPCs. The proposed modeling mechanism aims to facilitate the scientific measurement of
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.
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.
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.
5304492
Design specifications of a generic supply chain simulator
This paper describes a design specification for a generic, supply-chain-simulation system. The proposed simulation system is based on schedule-driven and stock-driven control methods to support the supply chain management. The simulation system includes three processing modes: business process flows, material process flows, and information process flows. The paper also discusses interface data requirements for the proposed supply-chain-simulation system.
206579905
Improving multistage network performance under uniform and hot-spot traffics
The major performance drawbacks of multistage interconnection networks are due to link contention and message blockage. To remedy this problem, the authors propose a switch design which uses two independent routes between each input port and each output port within a switch. With proper routing control mechanisms, the adverse effect on link conflicts can be greatly reduced. Various simulations are used to illustrate the performance improvement of this new design under both uniform and hot-spot traffic patterns.<<ETX>>
14604625
Single run optimization using the reverse-simulation method
An efticient “Simulation Optimization” technique is developed to solve system design problems which can not be expressed in explicit analytical or mathematical models. In particular, we explore a new paradigm called the “Reverse-Simulation optimization method” which is quite Merent from current simulation optimization methods in the literature. This paper focuses on the method of on-line determination of steady-state, which is a very important issue in ReverseSimulation optimization, and the construction of a Reverse-Simulation algorithm with expert systems. The proposed algorithm finds the steady-state of a system and an optimal state. The algorithm employs the Lyapunov exponent of Chaos theory to determine both the steady-state and optimal state of a system.
19081367
Robust technique for estimating the bearings of cyclostationary signals
This paper deals with the problem of direction finding using cyclostationary signals in the presence of cycle frequency error (CFE). By exploiting the signal cyclostationarity, cyclic MUSIC and conjugate cyclic MUSIC presented in Gardner (Cyclostationarity in Communications and Signal Processing, New York, 1994; Proc. IEEE 76 (1988) 845) have been shown to be effective for signal-selective direction finding. However, they suffer from severe performance degradation even if there is a small error in the cycle frequency of the signals of interest. In this paper, we first evaluate the performance of conjugate cyclic MUSIC when CFE exists. An analytical formula is derived to show the behavior of the performance degradation due to CFE. By exploiting the eigenstructure of the conjugate cyclic correlation matrix of the received array data, we develop a technique including a method for estimating the cycle frequency of the SOI and an efficient method in conjunction with a subspace-fitting algorithm to achieve robust direction finding against CFE. Several simulation examples confirming the theoretical analysis and showing the effectiveness of the proposed technique are also presented.
26477941
A novel direction-finding method for cyclostationary signals
We develop a method based on the phase-SCORE algorithm of Agee et al. (Proc. IEEE 78 (April 1990) 753) to achieve direction finding for cyclostationary signals. Using the weight obtained from the phase-SCORE algorithm, we construct a subspace orthogonal to the subspace spanned by the direction vectors of uncorrelated signals of interest (SOIs). Finding the directions of the uncorrelated SOIs is then performed according to a subspace-fitting concept. For coping with the coherence between SOIs, we incorporate the proposed method with the well-known spatial smoothing algorithm of Shan et al. (IEEE Trans. Acoust. Speech Signal Process ASSP-33 (August 1985) 806) to alleviate the performance degradation due to coherence. Simulation examples for illustration and comparison are also provided.