Showing papers by "Naval Postgraduate School published in 1999"
TL;DR: Three new heuristics, one for batch mode and two for immediate mode, are introduced as part of this research, revealing that the choice of which dynamic mapping heuristic to use in a given heterogeneous environment depends on parameters such as the structure of the heterogeneity among tasks and machines and the arrival rate of the tasks.
828 citations
Book•
01 Sep 1999TL;DR: The Promises and Challenges of Networked Virtual Environments: Real-Time System Design and Resource Management, and challenges in Net-VE Design and Development.
Abstract: 1. The Promises and Challenges of Networked Virtual Environments. What Is a Networked Virtual Environment? Graphics Engines and Displays. Control and Communication Devices. Processing Systems. Data Network. Challenges in Net-VE Design and Development. Network Bandwidth. Heterogeneity. Distributed Interaction. Real-Time System Design and Resource Management. Failure Management. Scalability. Deployment and Configuration. Conclusion. References. 2. The Origin of Networked Virtual Environments. Department of Defense Networked Virtual Environments. SIMNET. Distributed Interactive Simulation. Networked Games and Demos. SGI Flight and Dogfight. Doom. Other Games. Academic Networked Virtual Environments. NPSNET. PARADISE. DIVE. Brick Net. MR Toolkit Peer Package. Others. Conclusion. References. 3. A Networking Primer. Fundamentals of Data Transfer. Network Latency. Network Bandwidth. Network Reliability. Network Protocol. The BSD Sockets Architecture. Sockets and Ports. The Internet Protocol. Introducing the Internet Protocols for Net-Ves. Transmission Control Protocol. User Datagram Protocol. IP Broadcasting Using UDP. IP Multicasting. Selecting a Net-VE Protocol. Using TCP/IP. Using UDP/IP. Using IP Broadcasting. Using IP Multicasting. Conclusion. References. 4. Communication Architectures. Two Players on a LAN. Multiplayer Client-Server Systems. Multiplayer Client-Server, with Multiple-Server Architectures. Peer-to-Peer Architectures. Conclusion. References. 5. Managing Dynamic Shared State. The Consistency-Throughput Tradeoff. Maintaining Shared State Inside Centralized Repositories. Reducing Coupling through Frequent State Regeneration. Dead Reckoning of Shared State. Conclusion. References. 6. Systems Design. One Thread, Multiple Threads. Important Subsystems. Conclusion. References and Further Reading. 7. Resource Management for Scalability and Performance. An Information-Centric View of Resources. Optimizing the Communications Protocol. Controlling the Visibility of Data. Taking Advantage of Perceptual Limitations. Enhancing the System Architecture. Conclusion. References. 8. Internet Networked Virtual Environments. VRML-Based Virtual Environments. Virtual Reality Transfer Protocol. Internet Gaming. Conclusion. References. 9. Perspective and Predictions. Better Library Support. Toward a Better Internet. Research Frontiers. Past, Present, and Future. References. Appendix: Network Communication in C, C++, and Java. Using TCP/IP from C and C++. Managing Concurrent Connections in C and C++. Using TCP/IP from Java. Managing Concurrent Connections in Java. Using UDP/IP from C and C++. Using UDP/IP from Java. Broadcasting from C and C++. Broadcasting from Java. Multicasting from C and C++. Multicasting from Java. References. Index. 0201325578T04062001
782 citations
TL;DR: It is shown that, in expectation, z^*"n is a lower bound on z* and that this bound monotonically improves as n increases, and confidence intervals are constructed on the optimality gap for any candidate solution x@^ to SP.
698 citations
12 Apr 1999
TL;DR: Three new heuristics, one for batch and two for on-line, are introduced as part of this research, revealing that the choice of mapping heuristic depends on parameters such as: the structure of the heterogeneity among tasks and machines, the optimization requirements, and the arrival rate of the tasks.
Abstract: Dynamic mapping (matching and scheduling) heuristics for a class of independent tasks using heterogeneous distributed computing systems are studied. Two types of mapping heuristics are considered: on-line and batch mode heuristics. Three new heuristics, one for batch and two for on-line, are introduced as part of this research. Simulation studies are performed to compare these heuristics with some existing ones. In total, five on-line heuristics and three batch heuristics are examined. The on-line heuristics consider; to varying degrees and in different ways, task affinity for different machines and machine ready times. The batch heuristics consider these factors, as well as aging of tasks waiting to execute. The simulation results reveal that the choice of mapping heuristic depends on parameters such as: (a) the structure of the heterogeneity among tasks and machines, (b) the optimization requirements, and (c) the arrival rate of the tasks.
658 citations
TL;DR: Water-tunnel tests of a NACA 0012 airfoil that was oscillated sinusoidally in plunge are described in this article, where dye flow visualization and single-component laser Doppler velocimetry (LDV) measurements for a range of freestream speeds, frequencies, and amplitudes of oscillation are explored.
Abstract: Water-tunnel tests of a NACA 0012 airfoil that was oscillated sinusoidally in plunge are described. The flowered downstream of the airfoil was explored by dye flow visualization and single-component laser Doppler velocimetry (LDV) measurements for a range of freestream speeds, frequencies, and amplitudes of oscillation. The dye visualizations show that the vortex patterns generated by the plunging airfoil change from drag-producing wake flows to thrust-producing jet flows as soon as the ratio of maximum plunge velocity to freestream speed, i.e., the nondimensional plunge velocity, exceeds approximately 0.4. The LDV measurements show that the nondimensional plunge velocity is the appropriate parameter to collapse the maximum streamwise velocity data covering a nondimensional plunge velocity range from 0.18 to 9.3
326 citations
12 Apr 1999
TL;DR: A collection of eleven heuristics from the literature has been selected, implemented, and analyzed under one set of common assumptions and provides one even basis for comparison and insights into circumstances where one technique will outperform another.
Abstract: Heterogeneous computing (HC) environments are well suited to meet the computational demands of large, diverse groups of tasks (i.e., a meta-task). The problem of mapping (defined as matching and scheduling) these tasks onto the machines of an HC environment has been shown, in general, to be NP-complete, requiring the development of heuristic techniques. Selecting the best heuristic to use in a given environment, however, remains a difficult problem, because comparisons are often clouded by different underlying assumptions in the original studies of each heuristic. Therefore, a collection of eleven heuristics from the literature has been selected, implemented, and analyzed under one set of common assumptions. The eleven heuristics examined are opportunistic load balancing, user-directed assignment, fast greedy, min-min, max-min, greedy, genetic algorithm, simulated annealing, genetic simulated annealing, tabu, and A*. This study provides one even basis for comparison and insights into circumstances where one technique will outperform another. The evaluation procedure is specified, the heuristics are defined, and then selected results are compared.
259 citations
01 Nov 1999
TL;DR: In this article, the authors developed a preliminary ontology to identify a number of factors that influence maintenance and defined two common maintenance scenarios and considered the industrial issues associated with them, and presented the ontology in the form of a UML model.
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.
197 citations
TL;DR: In this paper, the seasonal ocean circulation and the seasonal thermal structure in the South China Sea (SCS) were studied numerically using the Princeton Ocean Model (POM) with 20-km horizontal resolution and 23 sigma levels conforming to a realistic bottom topography.
Abstract: The seasonal ocean circulation and the seasonal thermal structure in the South China Sea (SCS) were studied numerically using the Princeton Ocean Model (POM) with 20-km horizontal resolution and 23 sigma levels conforming to a realistic bottom topography. A 16-month control run was performed using climatological monthly mean wind stresses, restoring-type surface salt and heat, and observational oceanic inflow/outflow at the open boundaries. The seasonally averaged effects of isolated forcing terms are presented and analyzed from the following experiments: 1) nonlinear dynamic effects removed, 2) wind effects removed, and 3) open boundary inflow/outflow set to zero. This procedure allowed analysis of the contribution of individual parameters to the general hydrology and specific features of the SCS: for example, coastal jets, mesoscale topographic gyres, and countercurrents. The results show that the POM model has the capability of simulating seasonal variations of the SCS circulation and thermoha...
187 citations
08 Nov 1999
TL;DR: This paper describes the design, implementation, and preliminary testing of an inertial tracking system using a "complementary" filter based upon quaternions that is capable of tracking a rigid body through all orientations and is more efficient than those based on Euler angles.
Abstract: Joint angle determination for robots with flexible links can be difficult. Inertial orientation tracking combined with RF positioning provides an accurate method for determining end effector orientation and location. The same technology could also be used to determine human posture for the purpose of inserting humans in synthetic environments. Orientation filters based upon Euler angles suffer from singularities. This paper describes the design, implementation, and preliminary testing of an inertial tracking system using a "complementary" filter based upon quaternions. This filter is capable of tracking a rigid body through all orientations and is more efficient than those based on Euler angles. Results of qualitative tests of a prototype inertial angle tracking device are presented.
171 citations
13 Mar 1999
TL;DR: Results indicate that targeted search tasks are best served by a forward- up alignment while primed and naive search tasks (tasks requiring information from the world reference frame) prefer a north-up alignment.
Abstract: Navigation tasks in large virtual environments often call for the use of a virtual map. However, all maps are not alike. Performance on navigation tasks in general has been shown to vary depending on the orientation of the map with respect to the user's frame of reference. This paper reports the results of an experiment investigating orientation issues of virtual maps for use during navigation tasks. Participants were given a virtual map in either a north-up or forward-up configuration. Performance on search tasks was measured in terms of search time and errors. Results indicate that targeted search tasks (tasks requiring only the egocentric reference frame) are best served by a forward-up alignment while primed and naive search tasks (tasks requiring information from the world reference frame) prefer a north-up alignment. Both types of maps are affected by the ability of user to perform mental rotations.
160 citations
TL;DR: It is shown that well-typed concurrent programs are probabilistically noninterfering if every total command with a guard containing high variables executes atomically.
Abstract: In previous work (Smith and Volpano, Proceedings 25th Symposium on Principles of Programming Languages, San Diego, CA, 1998, pp. 355-364), we give a type system that guarantees that well-typed multi-threaded programs are possibilistically noninterfering. If thread scheduling is probabilistic, however, then well-typed programs may have probabilistic timing channels. We describe how they can be eliminated without making the type system more restrictive. We show that well-typed concurrent programs are probabilistically noninterfering if every total command with a guard containing high variables executes atomically. The proof uses the notion of a probabilistic state of a computation from Kozens work in the denotational semantics of probabilistic programs (Kozen, Journal of Computer and System Sciences 22 (1981), 328-350).^{2}
Stanford University1, University of Pennsylvania2, American University3, University of Virginia4, California Institute of Technology5, University of Wisconsin-Madison6, University of Massachusetts Amherst7, University of Mississippi8, Thomas Jefferson National Accelerator Facility9, University of Michigan10, University of Liverpool11, Lawrence Livermore National Laboratory12, University of Bonn13, University of Basel14, College of William & Mary15, Old Dominion University16, Yale University17, Tohoku University18, Naval Postgraduate School19, Temple University20, Kent State University21, Florida International University22, CERN23
TL;DR: In this paper, the cross section for scattering 29 GeV electrons from carbon at a laboratory angle of 4.5° was measured at SLAC, corresponding to 0.03.
TL;DR: In this paper, the authors presented the first study of Pulse-Width PulseFrequency (PWPF) modulated thruster control using command input shaping, which takes full advantage of the pseudolinear property of a PWPF modulator and integrates it with a command shaper to minimize the vibration induced by on-off thruster firing.
Abstract: Minimizing vibrations of a flexible spacecraft actuated by on-off thrusters is a challenging task. This paper presents the first study of Pulse-Width PulseFrequency (PWPF) modulated thruster control using command input shaping. Input shaping is a technique which uses shaped command to ensure zero residual vibration of a flexible structure. PWPF modulation is a control method which provides pseudo-linear operation for an on-off thruster. The proposed method takes full advantage of the pseudo-linear property of a PWPF modulator and integrates it with a command shaper to minimize the vibration of a flexible spacecraft induced by on-off thruster firing. Compared to other methods, this new approach has numerous advantages: 1) effectiveness in vibration suppression, 2) dependence only on modal frequency and damping, 3) robustness to variations in modal frequency and damping, 4) easy computation and 5) simple implementation. Numerical simulations performed on an eight-mode model of the Flexible Spacecraft Simulator (FSS) in the Spacecraft Research and Design Center (SRDC) at US Naval Postgraduate School (NPS) demonstrate the efficacy and robustness of the method.
TL;DR: Hardware and software design and testing results of the SANS are described and it is shown that results from tilt table testing and bench testing provide an effective means for tuning filter gains.
Abstract: A Small Autonomous Underwater Vehicle Navigation System (SANS) is being developed at the Naval Postgraduate School. The SANS is an integrated Global Positioning System/Inertial Navigation System (GPS/INS) navigation system composed of low-cost and small-size components. It is designed to demonstrate the feasibility of using a low-cost strap-down inertial measurement unit (IMU) to navigate between intermittent GPS fixes. The present hardware consists of a GPS/DGPS receiver, IMU, compass, water speed sensor, water depth sensor, and a data processing computer. The software is based on a 12-state complementary filter that combines measurement data from all sensors to derive a vehicle position/orientation estimate. This paper describes hardware and software design and testing results of the SANS. It is shown that results from tilt table testing and bench testing provide an effective means for tuning filter gains. Ground vehicle testing verifies the overall functioning of the SANS and exhibits an encouraging degree of accuracy.
TL;DR: The authors argue that the authors in this debate have largely been talking past one another because of a failure to distinguish three quite different questions: low turnout voters more likely to vote Democratic than high turnout voters, and should we expect that elections in which turnout is higher are ones in which we can expect Democrats to have done better?
Abstract: Controversy persists over the link between turnout and the likelihood of success of Democratic candidates (e.g., DeNardo, 1980, 1986; Zimmer, 1985; Tucker and Vedlitz, 1986; Piven and Cloward, 1988; Texeira, 1992; Radcliff, 1994, 1995; Erikson, 1995a, b). We argue that the authors in this debate have largely been talking past one another because of a failure to distinguish three quite different questions. The first question is: “Are low turnout voters more likely to vote Democratic than high turnout voters?” The second question is: “Should we expect that elections in which turnout is higher are ones in which we can expect Democrats to have done better?” The third question is the counterfactual: “If turnout were to have increased in some given election, would Democrats have done better?” We show the logical independence of the first two questions from one another and from the third, and argue that previous researchers have failed to recognize this logical independence – sometimes thinking they were answering question three when in fact they were answering either question one or question two. Reviewing previous research, we find that the answer to the first question once was YES but, for more recent elections at the presidential level, now appears to be NO, while, for congressional and legislative elections, the answer to the second question appears generally to be NO. However, the third question is essentially unanswerable absent an explicit model of why and how turnout can be expected to increase, and/or analyses of individual level panel data. Thus, the cross-sectional and pooled data analyses of previous research are of almost no value in addressing this third question.
10 May 1999
TL;DR: The task space ellipsoid is derived, both kinematics and dynamics, for a wheeled mobile manipulator which takes into account manipulation and locomotion and is able to visualize how the manipulator and the platform can contribute to a task execution.
Abstract: This paper presents an unified approach to the task space analysis of a wheeled mobile manipulator interacting with the environment. The system considered consists of two articulated manipulators atop a wheeled mobile platform handling a common object. We derive the task space ellipsoid, both kinematics and dynamics, for a wheeled mobile manipulator which takes into account manipulation and locomotion. The ellipsoid is able to visualize how the manipulator and the platform can contribute to a task execution by integrating the mobility of the platform with the manipulability of the arms as one unified measure. This measure can be useful not only for the task space analysis of a single mobile manipulator, but also for the coordination of multiple arms, mobile robots or mobile manipulators.
TL;DR: It is found that nighttime imagery provides adequate low-level image information for effective perceptual organization on a classification task, but that performance for exemplars within a given object category is dependent on the image type.
Abstract: This study investigated human perceptual performance allowed by relatively impoverished information conveyed in nighttime natural scenes. Researchers used images of nighttime outdoor scenes rendered in image-intensified low-light visible (i-squared) sensors, thermal infrared (ir) sensors, and an i-squared/ir fusion technique with information added. They found that nighttime imagery provides adequate low-level image information for effective perceptual organization on a classification task, but that performance for exemplars within a given object category is dependent on the image type. Overall performance was best with the false-color fused images. This is consistent with the suggestion in the literature that color plays a predominate role in perceptual grouping and segmenting of objects in a scene and supports the suggestion that the addition of color in complex achromatic scenes aids the perceptual organization required for visual search. The study addresses the issue of assessment of perceptual performance with alternative night-vision sensors and fusion methods and begins to characterize perceptual organization abilities permitted by the information in relatively impoverished images of complex scenes. Applications of this research include improving night vision, medical, and other devices that use alternative sensors or degraded imagery.
TL;DR: In this paper, the rotation of the elliptical eye in the context of barotropic dynamics at three levels were explored: linear waves on a Rankin vortex, nonlinear Kirchhoff vortex, and with a nonlinear spectral model.
Abstract: An elliptical eye that rotated cyclonically with a period of approximately 144 minutes in Typhoon Herb 1996 was documented. The elliptical region had a semimajor axis of 30 km and a semiminor axis of 20 km. Two complete periods of approximately 144 min were observed in the Doppler radar data. The rotation of the elliptical eye in the context of barotropic dynamics at three levels were explored: linear waves on a Rankin vortex, a nonlinear Kirchhoff vortex, and with a nonlinear spectral model. The linear wave theory involves the existence of both the high (potential) vorticity gradient near the eye edge and the cyclonic mean tangential flow in the typhoon. The propagation of (potential) vorticity waves in the cyclonic mean flow makes the elliptical eye rotate cyclonically. The rotation period is longer than the period of a parcel trajectory moving in the cyclonic mean flow around the circumference, because the vorticity wave propagates upwind. The nonlinear theory stems from the rotation of Kirchhoff’s vortex. Estimates of the eye rotation period from both linear and nonlinear theories agree with observations of the eye rotation period when the observed maximum wind from Herb is used. Nonlinear numerical computations suggest the importance of the interaction of neutral vorticity waves, which determine the shape and the rotation period of the eye. The calculations also support the rotation of the eye in approximately 144 min in the presence of axisymmetrization, vorticity redistribution, wave breaking, and vortex merging processes.
TL;DR: In this paper, nineteen isobaric RAFOS floats, placed in the California Undercurrent at intermediate depths (150-600 m) off Monterey and San Francisco, California, reveal a region of varying width of subsurface, poleward flow adjacent to the continental margin.
Abstract: During the period 1992–95, nineteen isobaric RAFOS floats, placed in the California Undercurrent at intermediate depths (150–600 m) off Monterey and San Francisco, California, reveal a region of varying width of subsurface, poleward flow adjacent to the continental margin. The float trajectories exhibit three patterns: poleward flow in the undercurrent; reversing, but predominately alongshore, flow adjacent to the continental margin;and, farther offshore, anticyclonic motion accompanied by slow westward drift. Flow continuity of the undercurrent exists between Pt. Reyes and at least Cape Mendocino with an average speed dependent on the float depth. Speeds were variable, but common features were acceleration occurring to the south of Pt. Arena and deceleration to the north of Cape Mendocino. An important mechanism for floats, and water, to enter the ocean interior from the undercurrent is through the formation of submesoscale coherent vortices.
06 Dec 1999
TL;DR: A preliminary security service taxonomy is defined and is used as a framework for defining the costs associated with network security services.
Abstract: A wide range of security services may be available to applications in a heterogeneous computer network environment. Resource management systems (RMSs) responsible for assigning computing and network resources to tasks need to know the resource-utilization costs associated with the various network security services. In order to understand the range of security services all RMS needs to manage, a preliminary security service taxonomy is defined. The taxonomy is used as a framework for defining the costs associated with network security services.
TL;DR: In this article, the effect of planetary vorticity gradient (beta) and the presence of a uniform mean flow on the intensification of tropical cyclones using a limited-area primitive equation model was studied.
Abstract: The effect of planetary vorticity gradient (beta) and the presence of a uniform mean flow on the intensification of tropical cyclones are studied using a limited-area primitive equation model. The most intense storm evolves on a constant-f plane with zero-mean flow and its structure is symmetric with respect to the vortex center. The presence of an environmental flow induces an asymmetry in a vortex due to surface friction. When f varies the vortex is distorted by the beta gyres. Fourier analysis of the wind field shows that a deepening cyclone is associated with a small asymmetry in the low-level wavenumber-one wind field. A small degree of asymmetry in the wind field allows a more symmetric distribution of the surface fluxes and low-level moisture convergence. On the other hand, a weakening or nonintensifying cyclone is associated with a larger asymmetry in its wavenumber-one wind field. This flow pattern generates asymmetric moisture convergence and surface fluxes and a phase shift may exist b...
22 Sep 1999
TL;DR: Safety and secrecy are formulated for a deterministic programming language and a safety property is defined as a set of program traces and secrecy isdefined as a binary relation on traces, characterizing a form of Noninterference.
Abstract: Safety and secrecy are formulated for a deterministic programming language. A safety property is defined as a set of program traces and secrecy is defined as a binary relation on traces, characterizing a form of Noninterference. Safety properties may have sound and complete execution monitors whereas secrecy has no such monitor.
01 Nov 1999
TL;DR: It is found that KBS can be developed and employed for effective knowledge management support and its field application, as part of a major reengineering engagement, reveals four important knowledge effects enabled by this KBS.
Abstract: A fundamental problem with knowledge management is the information technology (IT) employed to enable knowledge work appears to target data and information, as opposed to knowledge itself. In contrast, knowledge-based systems (KBS) maintain an explicit and direct focus on knowledge. The research described in this article is focused on innovating knowledge management through KBS technology. We refer to this KBS-enabled transformation of knowledge work as knowledge-based knowledge management. Drawing from the recent literature, we identify a number of key activities associated with knowledge management to establish a set of requirements for knowledge management support. We match these requirements with textbook capabilities of intelligent systems and use this analysis to evaluate KOPeR, a KBS employed to automate and support knowledge management in the reengineering domain. We find KOPeR possesses the capabilities required for knowledge management support. And its field application, as part of a major reengineering engagement, reveals four important knowledge effects enabled by this KBS. From this study, we also find KOPeR to be effective in its automation and support of key knowledge management activities. And through its successful use and knowledge effects in this study, we conclude that KBS can be developed and employed for effective knowledge management support.
11 Jan 1999
TL;DR: In this paper, a flapping-wing propulsion is investigated experimentally and numerically with direct comparisons between experimental and numerical thrust measurements for several geometrically simple con gurations.
Abstract: Flapping-wing propulsion is investigated experimentally and numerically with direct comparisons between experimental and numerical thrust measurements for several geometrically simple con gurations. Numerical simulations are performed using linear theory, and a previously developed, unsteady panel method that models one or two independently moving airfoils with three-degrees of freedom and non-linear deforming wakes. Experiments are carried out in the Naval Postgraduate School 5 5 low-speed tunnel. A apping mechanism that approximates the two-dimensional motions modeled by the panel code is suspended with cables in the wind tunnel, and thrust measurements are made by measuring the streamwise displacement of the model using a laser rangender. The experimental apping mechanism utilizes variable aspectratio wings and optional tip plates to investigate the e ect of three-dimensionality. The device aps two airfoils, each with two degrees of freedom and adjustable pitch and plunge amplitudes, and additional stationary wings may be attached up and/or downstream of the apping wings to investigate interference e ects.
TL;DR: In this paper, a cross-shore array of nine collocated pressure sensors and bidirectional current meters, extending from the shoreline to approximately 4.5m depth, are used to estimate the relative contributions of gravity waves (e.g., edge and leaky waves) and instabilities of the alongshore current (shear waves) to motions in the infragravity (frequencies nominally 0.004-0.05 Hz) band.
Abstract: Data from a cross-shore array of nine collocated pressure sensors and bidirectional current meters, extending from the shoreline to approximately 4.5-m depth, are used to estimate the relative contributions of gravity waves (e.g., edge and leaky waves) and instabilities of the alongshore current (shear waves) to motions in the infragravity (frequencies nominally 0.004–0.05 Hz) band. The ratio between frequency-integrated velocity and pressure variances is shown to be approximately equal to g/h for a broad spectrum of gravity waves independent of the mode mix of edge and leaky waves. Since shear waves have velocity to pressure variance ratios ≫ g/h, this ratio can be used to estimate the relative contributions of gravity and shear waves to the infragravity band. Outside the surf zone where the shear in the alongshore current is relatively weak, the observed velocity to pressure variance ratios are approximately equal to g/h, consistent with a gravity-dominated wave field. Inside the surf zone wher...
TL;DR: This fuzzy correlation approach is developed based on fuzzy clustering means algorithm and is applied to a two- and a four-dimensional multisensor–multitarget tracking system using Monte Carlo simulations.
TL;DR: In this paper, the authors compare observations to model output for these periods using the Los Alamos Parallel Ocean Program (POP) 1/6 deg (on average) global model, forced by ECMWF wind stresses for the period 1985 through 1995.
Abstract: The Indonesian Throughflow, weaving through complex topography, drawing water from near the division of the North Pacific and South Pacific water mass fields, represents a severe challenge to modeling efforts. Thermohaline observations within the Indonesian seas in August 1993 (southeast monsoon) and February 1994 (northwest monsoon) offer an opportunity to compare observations to model output for these periods. The simulation used in these comparisons is the Los Alamos Parallel Ocean Program (POP) 1/6 deg (on average) global model, forced by ECMWF wind stresses for the period 1985 through 1995. The model temperature structure shows discrepancies from the observed profiles, such as between 200 and 1200 dbar where the model temperature is as much as 38C warmer than the observed temperature. Within the 58‐288C temperature interval, the model salinity is excessive, often by more than 0.2. The model density, dominated by the temperature profile, is lower than the observed density between 200 and 1200 dbar, and is denser at other depths. In the model Makassar Strait, North Pacific waters are found down to about 250 dbar, in agreement with observations. The model sill depth in the Makassar Strait of 200 m, rather than the observed 550-m sill depth, shields the model Flores Sea from Makassar Strait lower thermocline water, causing the Flores lower thermocline to be dominated by salty water from the Banda Sea. In the Maluku, Seram, and Banda Seas the model thermocline is far too salty, due to excessive amounts of South Pacific water. Observations show that the bulk of the Makassar throughflow turns eastward into the Flores and Banda Seas, before exiting the Indonesian seas near Timor. In the model, South Pacific thermocline water spreads uninhibited into the Banda, Flores, and Timor Seas and ultimately into the Indian Ocean. The model throughflow transport is about 7.0 Sv (Sv [ 106 m3 s21) in August 1993 and 0.6 Sv in February 1994, which is low compared to observationally based estimates. However, during
TL;DR: This work investigates an important facet of process capability-stability-as defined and evaluated by trend, change and shape metrics, across releases and within a release and uses the NASA Space Shuttle flight software to illustrate the approach.
Abstract: In analyzing the stability of a software maintenance process, it is important that it is not treated in isolation from the reliability and risk of deploying the software that result from applying the process. Furthermore, we need to consider the efficiency of the test effort that is a part of the process and a determinate of reliability and risk of deployment. The relationship between product quality and process capability and maturity has been recognized as a major issue in software engineering based on the premise that improvements in the process will lead to higher-quality products. To this end, we have been investigating an important facet of process capability-stability-as defined and evaluated by trend, change and shape metrics, across releases and within a release. Our integration of product and process measurement serves the dual purpose of using metrics to assess and predict reliability and risk and to evaluate process stability. We use the NASA Space Shuttle flight software to illustrate our approach.
TL;DR: In this article, the decision, risk and management science program at the National Science Foundation (NSF) was used to support the development of a decision-making system for risk management.
Abstract: This work was supported by funding from the Decision, Risk and Management Science Program at the National Science Foundation.
TL;DR: Recommendations for research, development, and evaluation are made to appropriate sponsors, academic administrators, faculty members, training managers, and instructional developers, interested in realizing on-line learning.