15182689
Chameleon: a resource scheduler in a data grid environment
Grid computing is moving into two ways. The Computational Grid focuses on reducing execution time of applications that require a great number of computer processing cycles. The Data Grid provides the way to solve large scale data management problems. Data intensive applications such as High Energy Physics and Bioinformatics require both Computational and Data Grid features. Job scheduling in Grid has been mostly discussed from the perspective of computational Grid. However, scheduling on Data Grid is just a recent focus of Grid computing activities. In Data Grid environment, effective scheduling mechanism considering both computational and data storage resources must be provided for large scale data intensive applications. In this paper, we describe new scheduling model that considers both amount of computational resources and data availability in Data Grid environment. We implemented a scheduler, called Chameleon, based on the proposed application scheduling model. Chameleon shows performance improvements in data intensive applications that require both large number of processors and data replication mechanisms. The results achieved from Chameleon are presented.
16557699
Disconnected Operation Service in Mobile Grid Computing
In this paper, we discuss on the extension of grid computing systems in mobile computing environments, where mobile devices can be effectively incorporated into the grid either as service recipients or as more valuable service providers. First, based on the present grid architecture, we try to figure out what would be the newly required services in such a mobile/grid integrated architecture. There are a number of challenging issues when taking mobile environment into account, such as intermittent connectivity, device heterogeneity, and weak security. Among these issues to solve, we particularly focus on a disconnected operation problem in this paper since mobile resources are prone to frequent disconnections due to their confined communication range and device mobility. We develop a new job scheduling algorithm for mobile grid system and evaluate it by various methods such as mathematical analysis, simulation, and prototype implementation.
816246
Alternative Software Stacks for OGSA-based Grids
The Open Grid Services Architecture (OGSA) has been a major step forward for Grid Computing, but its de facto reliance on the Web Services Resource Framework (WSRF) and WS-Notification have left some in the community questioning if the Grid software and protocols have become too complex. In this paper, we consider the feasibility of an "alternative" software stack, based on WS-Transfer and WS-Eventing. We compare and evaluate WSRF/WS-Notification vs. WS-Transfer/WSEventing, first via a "hello world" service and then via a more complete Grid scenario for remote execution called "Grid-in-a-Box". By qualitatively and quantitatively evaluating each approach, we find that while subtle differences exist (e.g., the naming of resources, the creation of resources), the stacks are overwhelmingly equivalent in their functionality and implied performance. Overall, this paper uniquely shows that there could be alternative software stacks for OGSA-based Grids.
9375021
Dynamic Data Grid Replication Strategy Based on Internet Hierarchy
In data grid, large quantity of data files is produced and data replication is applied to reduce data access time. Efficiently utilizing grid resources becomes important research issue since available resources in grid are limited while large number of workloads and large size of data files are produced. Dynamic replication in data grid aims to reduce data access time and to utilize network and storage resources efficiently. This paper proposes a novel dynamic replication strategy, called BHR, which reduces data access time by avoiding network congestions in a data grid network. With BHR strategy, we can take benefits from ‘network-level locality’ which represents that required file is located in the site which has broad bandwidth to the site of job execution. We evaluate BHR strategy by implementing it in an OptorSim, a data grid simulator initially developed by European Data Grid Projects. The simulation results show that BHR strategy can outperform other optimization techniques in terms of data access time when hierarchy of bandwidth appears in Internet. BHR extends current site-level replica optimization study to the network-level.
20757485
Rigorous Modeling of Disk Performance for Real-Time Applications
Performance modeling of magnetic disks allows the prediction of the disk service time which is useful for on-line decision support for soft real-time applications. In this paper, we propose a new performance model of disk access time to estimate the bounded disk service time. Our proposed model focuses on modeling the head positioning time to fully utilize the disk I/O bandwidth by exploiting the geometric layout of the disk. The experimental results show that our proposed model can estimate the disk service time with less than 10% error on average.
1442053
User preferences when searching individual and integrated full-text databases
This paper addresses a crucial issue in the digital library environment: how to support effective interaction of users with heterogeneous and distributed information resources. We compared users' preference for systems which implement interaction with multiple databases through a common interface and with multiple databases as if they were one (integrated interaction) in an experiment in the Text REtrieval Conference (TREC) environment. Twenty-eight volunteers were recruited from the graduate students of School of Communication, Information, & Library Studies at Rutgers University. Significantly more subjects preferred the common interface (HERMES) to the integrated interface (HERA). For most of the subjects in this study, the greater control in HERMES outweighed the advantages of HERA such as convenience, efficiency, and ease of use. These results suggest that: (1) the general assumption of the information retrieval (IR) literature that an integrated interaction is best needs to be revisited; (2) it is important to allow for more user control in various ways in the distributed environment; and (3) for digital library purposes, it is important to characterize different databases to support user choice for integration.
13915681
Capturing and animating skin deformation in human motion
During dynamic activities, the surface of the human body moves in many subtle but visually significant ways: bending, bulging, jiggling, and stretching. We present a technique for capturing and animating those motions using a commercial motion capture system and approximately 350 markers. Although the number of markers is significantly larger than that used in conventional motion capture, it is only a sparse representation of the true shape of the body. We supplement this sparse sample with a detailed, actor-specific surface model. The motion of the skin can then be computed by segmenting the markers into the motion of a set of rigid parts and a residual deformation (approximated first as a quadratic transformation and then with radial basis functions). We demonstrate the power of this approach by capturing flexing muscles, high frequency motions, and abrupt decelerations on several actors. We compare these results both to conventional motion capture and skinning and to synchronized video of the actors.
310444
Managing energy-performance tradeoffs for multithreaded applications on multiprocessor architectures
In modern computers, non-performance metrics such as energy consumption have become increasingly important, requiring tradeoff with performance. A recent work has proposed performance-guaranteed energy management, but it is designed specifically for sequential applications and cannot be used to a large class of multithreaded applications running on high end computers and data servers.
 To address the above problem, this paper makes the first attempt to provide performance-guaranteed energy management for multithreaded applications on multiprocessor architectures. We first conduct a comprehensive study on the effects of energy adaptation on thread synchronizations and show that a multithreaded application suffers from not only local slowdowns due to energy adaptation, but also significant slowdowns propagated from other threads because of synchronization. Based on these findings, we design three Synchronization-Aware (SA) algorithms, LWT (Lock Waiting Time-based), CSL (Critical Section Length-based) and ODP (Operation Delay Propagation-based) algorithms, to estimate the energy adaptation-induced slowdowns on each thread. The local slowdowns are then combined across multiple threads via three aggregation methods (MAX, AVG and SUM) to estimate the overall application slowdown.
 We evaluate our methods using a large multithreaded commercial application, IBM DB2 with industrial-strength online transaction processing (OLTP) workloads, and six SPLASH parallel scientific applications. Our experimental results show that LWT combined with the MAX aggregation method not only controls the performance slow down within the specified limits but also conserves the most energy.
962129
Bayesian test for asymmetry and nonstationarity in MTAR model with possibly incomplete data
We propose an easy and efficient Bayesian test procedure for asymmetry and nonstationarity in momentum threshold autoregressive model with possibly incomplete data. Estimation of parameters and missing observations is done by using a Markov chain Monte Carlo (MCMC) method. Testing for asymmetry and nonstationarity is done via test of multiple hypotheses representing various types of symmetry/asymmetry and stationarity/nonstationarity. This allows simultaneous consideration of parameters relevant to asymmetry and nonstationarity of the model, and also enables us to find the sources of asymmetry and nonstationarity when they exist. Posterior probabilities of the hypotheses are easily computed by using MCMC outputs under the full model, with almost no extra cost. We apply the proposed method to a set of Korea unemployment rate data.