Showing papers by "Naval Postgraduate School published in 1992"
01 Jan 1992
590 citations
578 citations
TL;DR: In this paper, the authors used inertial-dissipation techniques to estimate wind stress from turbulence spectra, both at the offshore research platform Meetpost Noordwijk (MPN) and at a nearby ship.
Abstract: Turbulent fluxes have been measured in the atmospheric surface layer from a boom extending upwind from the Dutch offshore research platform Meetpost Noordwijk (MPN) during HEXMAX (Humidity Exchange over the Sea Main Experiment) in October–November, 1986. We started out to study eddy flux of water vapour, but discrepancies among simultaneous measurements made with three different anemometers led us to develop methods to correct eddy correlation measurements of wind stress for flow distortion by nearby objects. We then found excellent agreement among the corrected wind stress data sets from the three anemometers on the MPN boom and with eddy correlation measurements from a mast on a tripod. Inertial-dissipation techniques gave reliable estimates of wind stress from turbulence spectra, both at MPN and at a nearby ship. The data cover a range of wave ages and the results yield new insights into the variation of sea surface wind stress with sea state; two alternative formulas are given for the nondimensional surface roughness as a function of wave age.
412 citations
TL;DR: A conceptual model called REMAP (representation and maintenance of process knowledge) that relates process knowledge to the objects that are created during the requirements engineering process has been developed and a prototype environment that provides assistance to the various stakeholders involved in the design and management of large systems has been implemented.
Abstract: Support for various stakeholders involved in software projects (designers, maintenance personnel, project managers and executives, end users) can be provided by capturing the history about design decisions in the early stages of the system's development life cycle in a structured manner. Much of this knowledge, which is called the process knowledge, involving the deliberation on alternative requirements and design decisions, is lost in the course of designing and changing such systems. Using an empirical study of problem-solving behavior of individual and groups of information systems professionals, a conceptual model called REMAP (representation and maintenance of process knowledge) that relates process knowledge to the objects that are created during the requirements engineering process has been developed. A prototype environment that provides assistance to the various stakeholders involved in the design and management of large systems has been implemented. >
305 citations
TL;DR: In this article, it is shown that the Shapley value of these projected games can be interpreted as an index that measures the power of the players in the permission structure, and that the collection of these games forms a subspace of the vector space of all games with side payments on a specified player set.
Abstract: This paper is devoted to the game theoretic analysis of decision situations, in which the players have veto power over the actions undertaken by certain other players. We give a full characterization of the dividends in these games with a permission structure. We find that the collection of these games forms a subspace of the vector space of all games with side payments on a specified player set. Two applications of these results are provided. The first one deals with the projection of additive games on a permission structure. It is shown that the Shapley value of these projected games can be interpreted as an index that measures the power of the players in the permission structure. The second application applies the derived results on games, where the organization structure can be analysed separately from the production capacities of the participating players.
212 citations
TL;DR: A prototype flight simulator was built that is capable of simulating numerous types of aircraft simultaneously within a virtual world and provides the base functionality for the creation of a general purpose aerodynamic simulator that is particularly useful to aerodynamics students for graphically analyzing differing aircraft's stability and control characteristics.
Abstract: The Naval Postgraduate School NPS has actively explored the design and implementation of networked, real time, three-dimensional battlefield simulations on low-cost, commercially available graphics workstations. The most recent system, NPSNET, has improved in functionality to such an extent that it is considered a low-cost version of the Defense Advanced Research Project Agency's DARPA SIMNET system. To reach that level, it was necessary to economize in certain areas of the code so that real time performance occurred at an acceptable level. One of those areas was in aircraft dynamics. However, with “off-the-shelf” computers becoming faster and cheaper, real-time and realistic dynamics are no longer an expensive option. Realistic behavior can now be enhanced through the incorporation of an aerodynamic model. To accomplish this task, a prototype flight simulator was built that is capable of simulating numerous types of aircraft simultaneously within a virtual world. Besides being easily incorporated into NPSNET, such a simulator also provides the base functionality for the creation of a general purpose aerodynamic simulator that is particularly useful to aerodynamics students for graphically analyzing differing aircraft's stability and control characteristics. This system is designed for use on a Silicon Graphics workstation and uses the GL libraries. A key feature of the simulator is the use of quaternions for aircraft orientation representation to avoid singularities and high data rates associated with the more common Euler angle representation of orientation.
141 citations
TL;DR: Steady-state domain walls and kinks have been observed in one-dimensional nonlinear lattices that are damped and parametrically driven and a nonlinear Schr\"odinger theory is developed for kinks in the upper cutoff mode.
Abstract: Steady-state domain walls and kinks have been observed in one-dimensional nonlinear lattices that are damped and parametrically driven. These states are localized robust transition regions between two extended standing-wave domains of definite wave number. The observations are made in an experimental lattice of coupled pendulums and in simplified numerical models. A nonlinear Schr\"odinger theory is developed for kinks in the upper cutoff mode. There is currently no theory for the domain walls and noncutoff kinks, which are fundamentally new localized structures.
128 citations
TL;DR: In this paper, the relationship between organizational slack and risk taking in decision-making is investigated and some evidence on the role or organizational variables in risk-taking behavior is provided, where the authors measure organizational slack using various financial variables and find that firms with increases in organizational slack prior to the introduction of new products are more likely to adopt a higher risk product pricing strategy.
Abstract: Organizational change inevitably involves uncertainty and hence some risk taking. Tests the relationship between organizational slack and risk taking in organization decision making, and thus provides some evidence on the role or organizational variables in risk‐taking behaviour. Product pricing strategies are identified and characterized with respect to risk. Organizational slack is measured using various financial variables. Results indicate that firms which have increases in organizational slack prior to the introduction of new products are more likely to adopt a higher risk product pricing strategy. Also discusses implications regarding the measurement of slack using financial variables.
122 citations
TL;DR: In this article, a conceptual framework of public entrepreneurship is presented, which distinguishes between public entrepreneurs and other actors in the policy process, and clarify the differences between policy, political, executive, and bureaucratic entrepreneurs.
Abstract: This article presents a conceptualframeworkofpublic entrepreneurship Public entrepreneurship is defined as the generation ofa novel or innuuative idea and the design and implementation of the innovative idea into publicsector practice The conceptualfiamework is used to distinguish between public entrepreneurs and other actors in the policy process, and to clarify the differences between policy, political, executive, and bureaucratic entrepreneurs Taking a functionalist perspective, the article difmentintes between individual and coZkctiue entrepreneurship and ginezates pmpaitims to move us cher to a theory of public entrepreneurship
105 citations
01 Jan 1992
TL;DR: Maschler and Owen as mentioned in this paper introduced a new generalization of the Shapley value for a class of NTU games, which was quite narrow; namely, the class of hyperplane games.
Abstract: In [Maschler and Owen, 1989], a new generalization of the Shapley value for a class of NTU games was introduced. The motivation was a desire to preserve as much as possible the consistency property of the Shapley value for TU games, in the sense of [Hart and Mas-Colell, 1989]. It turned out that the new value resulted from an intuitive dynamic process which was interesting also for the class of TU games. Unfortunately, the class of NTU games was quite narrow; namely, the class of hyperplane games. The purpose of this paper is to extend the definition to the general class of NTU games, whose coalition functions satisfy (essentially) the usual requirements.
101 citations
TL;DR: The main purpose of as discussed by the authors is to provide a graph-theoretical characterization of this family of games whose associated hypergraphs we call strongly balanced: they show that the strong balancedness condition is equivalent to thenormality of the hypergraph.
Abstract: Kaneko/Wooders (1982) derived a list of necessary and sufficient conditions for a partitioning game to have a nonempty core regardless of the payoff functions of its effective coalitions. The main purpose of our paper is to provide a graph-theoretical characterization of this family of games whose associated hypergraphs we callstrongly balanced: we show that the strong balancedness condition is equivalent to thenormality of the hypergraph, which is a type ofcoloring property (Lovasz (1972)). We also study interesting economic examples ofcommunication andassignment games and provide direct proofs that their associated hypergraphs are strongly balanced.
01 Jan 1992
TL;DR: The Second (1992) International Offshore and Polar Engineering Conference as mentioned in this paper was held in San Francisco, USA, 14-19 June 1992, 14:19-21 June 1992.
Abstract: Proceedings of the Second (1992) International Offshore and Polar Engineering Conference
San Francisco, USA, 14-19 June 1992
TL;DR: In this article, the Muller-type coupled integral equations are derived for the surface electric and magnetic currents, and the power reflection coefficient is defined in terms of the scattered far fields.
Abstract: Plane wave scattering from lossy, periodic surfaces with periodicity in one direction is considered for arbitrary polarization and incidence angles The material is assumed to be homogeneous and characterized by complex values of permittivity and permeability Muller-type coupled integral equations are derived for the surface electric and magnetic currents The power reflection coefficient is defined in terms of the scattered far fields The integral equations are solved by the boundary element method (BEM) with constant elements Arbitrary surfaces are accommodated by approximating the actual profile by means of linear segments Other speed-up techniques are utilized to generate a numerically efficient solution Substantial comparison is made for special cases to verify the formulation The reflection coefficient is calculated for a variety of surface shapes A new profile shape is presented that results in a lower reflection coefficient than the commonly used triangular shape >
01 Jul 1992
TL;DR: A taxonomy is introduced in the review of existing research undertakings and exploratory developments to contrast and compare various approaches to federating databases and systems.
Abstract: The issues and solutions for the interoperability of a class of heterogeneous databases and their database systems are expounded in two parts. Part I presents the data-sharing issues in federated databases and systems. Part II, which will appear in a future issue, explores resource-consolidation issues. Interoperability in this context refers to data sharing among heterogeneous databases, and to resource consolidation of computer hardware, system software, and support personnel. Resource consolidation requires the presence of a database system architecture which supports the heterogeneous system software, thereby eliminating the need for various computer hardware and support personnel. The class of heterogeneous databases and database systems expounded herein is termed federated, meaning that they are joined in order to meet certain organizational requirements and because they require their respective application specificities, integrity constraints, and security requirements to be upheld. Federated databases and systems are new. While there are no technological solutions, there has been considerable research towards their development. This tutorial is aimed at exposing the need for such solutions. A taxonomy is introduced in our review of existing research undertakings and exploratory developments. With this taxonomy, we contrast and compare various approaches to federating databases and systems.
TL;DR: It is shown that three separate but related functions comprise an integrated reliability program: prediction, control, and assessment.
Abstract: The experience of a team that evaluated many reliability models and tried to validate them for the on-board system software of the National Aeronautics and Space Administration's (NASA's) space shuttle is presented It is shown that three separate but related functions comprise an integrated reliability program: prediction, control, and assessment The application of the reliability model and the allocation of test resources as part of a testing strategy are discussed >
TL;DR: In this article, field data from both the SUPERDUCK experiment (a barred beach) and the l980 NSTS experiment, at Leadbetter Beach, Santa Barbara, California (a plane beach), are used to compare quantitatively the model of Bowen and Holman (which is extended to include the effects of dissipation due to bottom friction) with observation Observed frequency-cyclic wavenumber (f-K) spectra (constructed from alongshore arrays of velocity measurements made in about 15-2 m of water in the trough of the bar at SUPER
Abstract: Low-frequency (<001 Hz) oscillations in the surf zone longshore current with wavelengths too small (<300 m) to be surface gravity waves were observed during the 1986 SUPERDUCK experiment at Duck, North Carolina The observations suggest that these oscillations are dynamically linked to the mean longshore current in the surf zone, leading Bowen and Holman to propose that the observed oscillations are manifestations of a shear instability in the longshore current In this paper, field data from both the SUPERDUCK experiment (a barred beach) and the l980 NSTS experiment, at Leadbetter Beach, Santa Barbara, California (a plane beach), are used to compare quantitatively the model of Bowen and Holman (which is extended to include the effects of dissipation due to bottom friction) with observation Observed frequency-cyclic wavenumber (f-K) spectra (constructed from alongshore arrays of velocity measurements made in about 15–2 m of water in the trough of the bar at SUPERDUCK, and in about 1 m at NSTS)
TL;DR: Diversity is found to completely negate degradation of the self-normalized receiver caused by partial-band interference and offers definite receiver performance improvement when the direct signal component is weak.
Abstract: Error probability analysis is performed for a binary orthogonal frequency-shift-keying (FSK) receiver using fast frequency-hopped (FFH) spread-spectrum waveforms transmitted over a frequency-nonselective slowly fading channel with partial-band interference. Diversity is performed using multiple hops per data, bit. A nonlinear combination procedure referred to as self-normalization combining is used by the receiver to minimize partial-band interference effects. Diversity is found to completely negate degradation of the self-normalized receiver caused by partial-band interference and offers definite receiver performance improvement when the direct signal component is weak. The self-normalized receiver is sensitive to fading channels. For severe channel fading, the performance of a conventional noncoherent binary FSK receiver is generally either equivalent or superior to that of the self-normalized receiver. >
02 Jun 1992
TL;DR: The autonomous underwater vehicle (AUV) integrated simulator has been designed to support complete scientific visualization of AUV vehicle performance, and use of well-defined, user-readable mission log files as the data transfer mechanism allows consistent and repeatable simulation of all AUV operations.
Abstract: The autonomous underwater vehicle (AUV) integrated simulator has been designed to support complete scientific visualization of AUV vehicle performance. High-resolution 3D graphics workstations can provide real-time representations of vehicle dynamics, control system behavior, mission execution, sonar processing and object classification. Use of well-defined, user-readable mission log files as the data transfer mechanism allows consistent and repeatable simulation of all AUV operations. Examples of integrated simulation are provided using the Naval Postgraduate School AUV, an eight-foot, 387-pound untethered robot submarine designed for research in adaptive control, mission planning, mission execution, and post-mission data analysis. >
TL;DR: This work overviews model integration capabilities in existing executable modeling languages, discusses current theoretical approaches to model integration, and proposes a process-oriented conceptualization and associated constructs that overcome limiting assumptions.
Abstract: Development of large-scale models often involves-or, certainly could benefit from-linking existing models. This process is termed model integration and involves two related aspects: 1 the coupling of model representations, and 2 the coupling of the processes for evaluating, or executing, instances of these representations. Given this distinction, we overview model integration capabilities in existing executable modeling languages, discuss current theoretical approaches to model integration, and identify the limiting assumptions implicitly made in both cases. In particular, current approaches assume away issues of dynamic variable correspondence and synchronization in composite model execution. We then propose a process-oriented conceptualization and associated constructs that overcome these limiting assumptions. The constructs allow model components to be used as building blocks for more elaborate composite models in ways unforeseen when the components were originally developed. While we do not prove the sufficiency of the constructs over the set of all model types and integration configurations, we present several examples of model integration from various domains to demonstrate the utility of the approach.
TL;DR: In this paper, the authors measured the frequency response of a thermoacoustic prime mover with respect to the mean gas pressure and temperature gradient across the stack of the stack.
Abstract: The frequency response of a thermoacoustic prime mover has been measured as a function of the mean gas pressure and temperature gradient across the prime mover stack. The quality factor Q and resonance frequency can be determined from the response. As the temperature gradient is increased, the Q increases, indicating a decrease in attenuation across the stack. At sufficiently large temperature differences (∼300 K), the resonator goes into self‐oscillation, indicating negative attenuation. Measurements are reported for helium and argon at pressures ranging from 170–500 kPa and temperature gradients ranging from zero to that required for onset of self‐oscillation. The results are explained in terms of a counterpropagating, plane‐wave analysis, based on techniques commonly used in porous media investigations. In general, the predictions of the analysis are in good agreement with experiment. The predictions of Q and the change in resonance frequency with mean gas pressure are within approximately 5% and 0.4% of measured values for the no temperature gradient cases. In the cases where temperature gradients are present, the agreement is quite good for the two highest mean pressures reported (370 and 500 kPa). There are some noticeable discrepancies at the lowest pressure (170 kPa). The reasons for these discrepancies are unknown.
TL;DR: Sea ice classification accuracy using standard statistics and higher order texture statistics generated from grey-level co-occurrence (GLC) matrices were compared for synthetic aperture radar data collected during the Marginal Ice Zone Experiment in April 1987, suggesting that standard statistics should be used for sea ice classification.
Abstract: Sea ice classification accuracy using standard statistics and higher order texture statistics generated from grey-level co-occurrence (GLC) matrices were compared for synthetic aperture radar (SAR) data collected during the Marginal Ice Zone Experiment (MIZEX) in April 1987. Standard stepwise discriminate analysis was used to identify the statistics modes useful for discrimination. Range was the most effective statistic, correctly classifying the ice types 75% of the time. Overall, the standard statistics (mean, variance, range, etc.) outperformed the texture statistics (87% accuracy vs. 75% accuracy). Given the added difficulty and computational cost of generating texture statistics, this result suggests that standard statistics should be used for sea ice classification. Odden and multiyear ice categories were the most difficult to statistically separate for these data. >
TL;DR: In this paper, the upward transfer of heat from ocean to atmosphere is examined for an Arctic lead, a break in the Arctic ice which allows contact between the cold atmosphere and the relatively warm ocean.
Abstract: The upward transfer of heat from ocean to atmosphere is examined for an Arctic “lead”, a break in the Arctic ice which allows contact between the cold atmosphere and the relatively warm ocean. We employ a large-eddy model to compute explicitly the three-dimensional turbulent response of the atmosphere to a lead of 200 m width. The surface heat flux creates a turbulent “plume” of individual quasi-random eddies, not a continuous updraft, which penetrate into the stable atmosphere and transport heat upward.
TL;DR: In this paper, the energy transfer into the harmonics and the resonant modes of both harmonic and anharmonic closed tubes driven at resonance (∼200 Hz) were compared with calculations using Coppens and Sanders' formulation.
Abstract: Recent developments in thermoacoustic devices have generated a renewed interest in finite amplitude standing waves in resonant cavities. Such devices can generate standing waves with acoustic pressure amplitudes on the order of 10% of ambient pressure. The similarity between previously observed finite amplitude waveforms in closed tubes and those in prime movers could be modeled as anharmonic resonating cavities. Measurements of the energy transfer into the harmonics and the resonant modes of both harmonic and anharmonic closed tubes driven at resonance (∼200 Hz) will be presented. These measurements were compared with calculations using Coppens and Sanders’ formulation [A. B. Coppens and J. V. Sanders, ‘‘Finite‐amplitude standing waves within real cavities,’’ J. Acoust. Soc. Am. 58, 1133–1140 (1975)], which requires the measured quality factors and resonance frequencies. [Work supported by ONR and the NPS Research Program.]
TL;DR: In this paper, the development and structure of flow downstream of one row and downstream of two staggered rows of film-cooling holes with compound angle orientations were described, where holes are inclined at 35 deg with respect to the test surface when projected into the streamwise/normal plane, and 30 deg with relative position to the ground surface when projecting into the span-wise or normal plane.
Abstract: Experimental results are presented that describe the development and structure of flow downstream of one row and downstream of two staggered rows of film-cooling holes with compound angle orientations. With the compound angle configuration, holes are inclined at 35 deg with respect to the test surface when projected into the streamwise/normal plane, and 30 deg with respect to the test surface when projected into the spanwise/normal plane. Within each row, holes are spaced 7.8 hole diameters apart, which gives 3.9d spacing between adjacent holes,for the staggered row arrangement
01 Jan 1992
TL;DR: In this article, the development and structure of flow downstream of one row and downstream of two staggered rows of film-cooling holes with compound angle orientations were described, where holes are inclined at 35 deg with respect to the test surface when projected into the streamwise/normal plane, and 30 deg with relative position to the ground surface when projecting into the span-wise or normal plane.
Abstract: Experimental results are presented that describe the development and structure of flow downstream of one row and downstream of two staggered rows of film-cooling holes with compound angle orientations. With the compound angle configuration, holes are inclined at 35 deg with respect to the test surface when projected into the streamwise/normal plane, and 30 deg with respect to the test surface when projected into the spanwise/normal plane. Within each row, holes are spaced 7.8 hole diameters apart, which gives 3.9d spacing between adjacent holes,for the staggered row arrangement
TL;DR: In this paper, a dynamic stall facility offering a unique new capability for studies of compressibility effects on dynamic stall is described, which features complete visual access by mounting the test airfoil between optical-quality glass windows which are rotated in unison to produce the oscillating air-foil motion associated with helicopter rotor dynamic stall.
Abstract: A dynamic stall facility offering a unique new capability for studies of compressibility effects on dynamic stall is described. This facility features complete visual access by mounting the test airfoil between optical-quality glass windows which are rotated in unison to produce the oscillating airfoil motion associated with helicopter rotor dynamic stall. By using the density gradients associated with the rapidly changing dynamic stall flow field, this facility permits simultaneous detailed investigation of the flow on the surface as well as in the flow field surrounding airfoils experiencing dynamic stall.
07 Jan 1992
TL;DR: The authors describe the state-of-the-art in rapid prototyping and discuss technologies that improve the future outlook for prototyping, such as prototyping languages, software reuse, and designer interfaces.
Abstract: Rapid software prototyping is an iterative software development methodology aimed at improving the analysis, design, and development of proposed systems. The paper describes rapid prototyping at the system and software levels and reviews the characteristics of computer-aided prototyping. The authors then describe the state-of-the-art in rapid prototyping and discuss technologies that improve the future outlook for prototyping, such as prototyping languages, software reuse, and designer interfaces. To add some cohesion to the concepts, they describe the characteristics of a computer-aided rapid prototyping system. Finally, they provide summaries of the outstanding papers that comprise the rapid prototyping mini-track. >
TL;DR: The geostrophic drag coefficient was most sensitive to the temperature difference across the boundary layer from the surface to the top of the inversion as mentioned in this paper, and the median α was 25° with hinge values of 15° and 32°.
Abstract: The geostrophic drag coefficient, Cg ≡ u*/G, and turning angle, α were measured October through November 1988 from a 120 km array of 6 drifting buoys and a drifting ship in the northern Barents Sea/Arctic Ocean during CEAREX; u* is the friction velocity, G is the geostrophic wind, and α is the angle between surface stress and equation image . The median Cg was 0.029 with hinge values (quartiles) of 0.023 and 0.034 and the median α was 25° with hinge values of 15° and 32°. The median values are representative for the nonsummer Arctic away from marginal seas and marginal ice zones. Surface air temperature, cloud amount, and the lapse rate above the inversion base were not good predictors of the influence of boundary layer stability on Cg. The geostrophic drag coefficient was most sensitive to the temperature difference across the boundary layer from the surface to the top of the inversion. DOI: 10.1034/j.1600-0870.1992.t01-5-00006.x