Naval Postgraduate School

About: Naval Postgraduate School is a education organization based out in Monterey, California, United States. It is known for research contribution in the topics: Tropical cyclone & Boundary layer. The organization has 5246 authors who have published 11614 publications receiving 298300 citations. The organization is also known as: NPS & U.S. Naval Postgraduate School.

A unified approach to time- and frequency-domain realization of FIR adaptive digital filters

Abstract: Specific implementations of the finite impulse response (FIR) block adaptive filter in the frequency domain are presented and some of their important properties are discussed. The time-domain block adaptive filter implemented in the frequency domain is shown to be equivalent to the frequency-domain adaptive filter (derived in the frequency domain), provided data sectioning is done properly. All of the known time- and frequency-domain adaptive filters [1]-[12], [16]-[18] are contained in the set of possible block adaptive filter structures. Thus, the block adaptive filter is generic and its formulation unifies the current theory of time- and frequency-domain FIR adaptive filter structures. A detailed analysis of overlap-save and overlap-add implementations shows that the former is to be preferred for adaptive applications because it requires less computation, a fact that is not true for fixed coefficient filters.

Towards an Ontology of software maintenance

Abstract: SUMMARY We suggest that empirical studies of maintenance are difficult to understand unless the context of the study is fully defined. We developed a preliminary ontology to identify a number of factors that influence maintenance. The purpose of the ontology is to identify factors that would affect the results of empirical studies. We present the ontology in the form of a UML model. Using the maintenance factors included in the ontology, we define two common maintenance scenarios and consider the industrial issues associated with them. Copyright © 1999 John Wiley & Sons, Ltd.

Microstructural evolution in commercial purity aluminum during high-pressure torsion

Abstract: An investigation was conducted to evaluate the microstructural evolution occurring in disks of commercial purity aluminum processed by high-pressure torsion (HPT) under constrained conditions. Microhardness measurements were taken to assess the variation in hardness across the diameters of disks subjected to different imposed strains and the microstructures were observed at the edges and in the centers of the disks using transmission electron microscopy. The results show the microhardness is lower and there is less grain refinement in the central regions of the disks in the initial stages of torsional straining but the microstructures become reasonably homogeneous across the disks at high imposed strains.

Integrated analysis and design of knowledge systems and processes

Abstract: Although knowledge management has been investigated in the context of decision support and expert systems for over a decade, interest in and attention to this topic have exploded recently. But integration of knowledge process design with knowledge system design is strangely missing from the knowledge management literature and practice. The research described in this chapter focuses on knowledge management and system design from three integrated perspectives: 1 reengineering process innovation, 2 expert systems knowledge acquisition and representation, and 3 information systems analysis and design. Through careful analysis and discussion, we integrate these three perspectives in a systematic manner, beginning with analysis and design of the enterprise process of interest, progressively moving into knowledge capture and formalization, and then system design and implementation. Thus, we develop an integrated approach that covers the gamut of design considerations from the enterprise process in the large, through alternative classes of knowledge in the middle, and on to specific systems in the detail. We show how this integrated methodology is more complete than existing developmental approaches and illustrate the use and utility of the approach through a specific enterprise example, which addresses many factors widely considered important in the knowledge management environment. Using the integrated methodology that we develop and illustrate in this article, the reader can see how to identify, select, compose and integrate the many component applications and technologies required for effective knowledge system and process design.

Carbon Nanotubes: Reinforced Metal Matrix Composites

Abstract: From the Foreword, written by legendary nano pioneer M. Meyyappan, Chief Scientist for Exploration Technology NASA Ames Research Center, Moffett Field, California, USA: "…there is critical need for a book to summarize the status of the field but more importantly to lay out the principles behind the technology. This is what Professor Arvind Agarwal and his co-workers … have done here." Carbon Nanotubes: Reinforced Metal Matrix Composites reflects the authors’ desire to share the benefits of nanotechnology with the masses by developing metal matrix carbon nanotube (MM-CNT) composites for large-scale applications. Multiwall carbon nanotubes can now be produced on a large scale and at a significantly reduced cost. The book explores potential applications and applies the author’s own research to highlight critical developmental issues for different MM-CNT composites—and then outline novel solutions. With this problem-solving approach, the book explores: Advantages, limitations, and the evolution of processing techniques used for MM-CNT composites Characterization techniques unique to the study of MM-CNT composites—and the limitations of these methods Existing research on different MM-CNT composites, presented in useful tables that include composition, processing method, quality of CNT dispersion, and properties The micro-mechanical strengthening that results from adding CNT The applicability of micro-mechanics models in MM-CNT composites Significance of chemical stability for carbon nanotubes in the metal matrix as a function of processing, and its impact on CNT/metal interface and mechanical properties Computational studies that have not been sufficiently covered although they are essential to research and development The critical issue of CNT dispersion in the metal matrix, as well as a unique way to quantify CNT distribution and subsequently improve control of the processing parameters for obtaining improved properties Carbon Nanotubes: Reinforced Metal Matrix Composites paints a vivid picture of scientific and application achievements in this field. Exploring the mechanisms through which CNTs are enhancing the properties of different metal-based composites, the authors provide a roadmap to help researchers develop MM-CNT composites and choose potential materials for use in emerging areas of technology.