42385078
Using Earned Value Management for COTS-Based Systems: Issues and Recommendations
Earned value management (EVM) has long been used by organizations to plan, monitor, and control the development and evolution of custom developed systems. EVM was developed for managing such projects, and assumes a waterfall development model. COTS-based systems (CBS), on the other hand, are formed and evolved through the selection and composition of pre-existing, off-the-shelf packages or components with potentially some number of custom components. Experience indicates that a spiral or iterative development process is a key to success with CBS. While EVM has been applied to CBS projects, the results have not been uniformly satisfying. This paper explores the fundamental challenges in using EVM with CBS, and proposes adaptations to some of the principals of EVM to render it more suitable for CBS development.
33417779
Implementing Large-Scale COTS Reengineering within the United States Department of Defense
This paper reports on empirical research into the organizational and process changes necessary to implement large-scale reengineering using COTS. The research goal is to identify how these changes can be effected within the context of the existing United States Department of Defense acquisition management, requirements management, and planning, programming, and budgeting systems. While this effort is still in its early stages, initial results indicate that there are significant challenges in developing and defending budget inputs to support an evolutionary COTS-oriented acquisition model. At the same time, recent changes in acquisition constraints and other mitigating circumstances are being exploited to improve the likelihood of success.
952506
ID Modulation: Embedding Sensor Data in an RFID Timeseries
This paper reports the first use of ID Modulation to embed a bitstream representing sensor information in a standards-compliant Radio Frequency Identification (RFID) channel. Like other forms of information hiding, ID Modulation embeds a new, lower bit-rate channel in a pre-existing host channel, without requiring any changes to the protocols defining the host channel. Like most other forms of information hiding, the embedded data is represented as correlations introduced into the host channel data stream. Most previous applications of information hiding have emphasized either secrecy (as in steganography) or robustness to removal (as in watermarking). The benefit of information hiding that is most important for the application reported here is backward compatibility with pre-existing standards and hardware. It has allowed us to build a new communication layer (for transmitting sensor data) on top of current RFID infrastructure.
17392905
Replacement Strategies in Steady State Genetic Algorithms: Static Environments
Recent years have seen increasing numbers of applications of Evolutionary Algorithms to non-stationary environments such as on-line process control. Studies have indicated that Genetic Algorithms using "Steady State" models demonstrate a greater ability to track moving optima than those using "Generational" models, however implementing the former requires an additional choice of which members of the current population should be replaced by new offspring. In this paper a number of selection and replacement strategies are compared for use in Steady State Genetic Algorithms working as function optimisers in dynamic environments. In addition to an algorithm with fixed mutation rates, the strategies are also compared in algorithms employing Cobb's Hypermutation method for tracking environmental changes. On-line and off-line metrics are used for comparison, which correspond to different types of real-world applications. In both cases it is shown that algorithms employing some kind of elitism outperform those that do not, which is related to previous studies on stationary environments. An investigation is made of various methods of implementing elitism, including an implicit method, "conservative" selection. It is shown that the latter, in addition to being computationally simpler, produces significantly better results on the problems used, and reasons are given for this behaviour.
12656940
Towards Semantic Universal Multimedia Access
15945659
Distributed Query Processing on the Grid
Distributed query processing (DQP) has been widely used in data intensive applications where data of relevance to users is stored in multiple locations. This paper argues: (i) that DQP can be important in the Grid, as a means of providing high-level, declarative languages for integrating data access and analysis; and (ii) that the Grid provides resource management facilities that are useful to developers of DQP systems. As well as discussing and illustrating how DQP technologies can be deployed within the Grid, the paper describes a prototype implementation of a DQP system running over Globus.
16057397
Measuring and modelling the performance of a parallel ODMG compliant object database server
Object database management systems (ODBMSs) are now established as the database management technology of choice for a range of challenging data intensive applications. Furthermore, the applications associated with object databases typically have stringent performance requirements, and some are associated with very large data sets. An important feature for the performance of object databases is the speed at which relationships can be explored. In queries, this depends on the effectiveness of different join algorithms into which queries that follow relationships can be compiled. This paper presents a performance evaluation of the Polar parallel object database system, focusing in particular on the performance of parallel join algorithms. Polar is a parallel, shared-nothing implementation of the Object Database Management Group (ODMG) standard for object databases. The paper presents an empirical evaluation of queries expressed in the ODMG Query Language (OQL), as well as a cost model for the parallel algebra that is used to evaluate OQL queries. The cost model is validated against the empirical results for a collection of queries using four different join algorithms, one that is value based and three that are pointer based. Copyright © 2005 John Wiley & Sons, Ltd.