Showing papers by "Naval Postgraduate School published in 2001"

Communicating and Controlling Strategy: An Empirical Study of the Effectiveness of the Balanced Scorecard

Abstract: This paper reports evidence on the effectiveness of the Balanced Scorecard (BSC) as a strategy communication and management‐control device. This study first reviews communication and management control literatures that identify attributes of effective communication and control of strategy. Second, the study offers a model of communication and control applicable to the BSC. The study then analyzes empirical interview and archival data to model the use and assess the communication and control effectiveness of the BSC. The study includes data from multiple divisions of a large, international manufacturing company. Data are from BSC designers, administrators, and North American managers whose divisions are objects of the BSC. The study accumulates evidence regarding the challenges of designing and implementing the BSC faced by even a large, well‐funded company. These findings may be general‐izable to other companies adopting or considering adopting the BSC as a strategic and management control device. Data in...

An extended Kalman filter for quaternion-based orientation estimation using MARG sensors

Abstract: Presents an extended Kalman filter for real-time estimation of rigid body orientation using the newly developed MARG (magnetic, angular rate, and gravity) sensors. Each MARG sensor contains a three-axis magnetometer, a three-axis angular rate sensor, and a three-axis accelerometer. The filter represents rotations using quaternions rather than Euler angles, which eliminates the long-standing problem of singularities associated with attitude estimation. A process model for rigid body angular motions and angular rate measurements is defined. The process model converts angular rates into quaternion rates, which are integrated to obtain quaternions. The Gauss-Newton iteration algorithm is utilized to find the best quaternion that relates the measured accelerations and earth magnetic field in the body coordinate frame to calculated values in the earth coordinate frame. The best quaternion is used as part of the measurements for the Kalman filter. As a result of this approach, the measurement equations of the Kalman filter become linear, and the computational requirements are significantly reduced, making it possible to estimate orientation in real time. Extensive testing of the filter with synthetic data and actual sensor data proved it to be satisfactory. Test cases included the presence of large initial errors as well as high noise levels. In all cases the filter was able to converge and accurately track rotational motions.

Possible Roles of Atlantic Circulations on the Weakening Indian Monsoon Rainfall–ENSO Relationship

Abstract: Since the 1970s, the inverse relationship between the Indian monsoon rainfall and the El Nino–Southern Oscillation (ENSO) has weakened considerably. The cause for this breakdown is shown to be most likely the strengthening and poleward shift of the jet stream over the North Atlantic. These changes have led to the recent development of a significant correlation between wintertime western European surface air temperatures and the ensuing monsoon rainfall. This western Europe winter signal extended eastward over most of northern Eurasia and remained evident in spring, such that the effect of the resulting meridional temperature contrast was able to disrupt the influence of ENSO on the monsoon.

The communication characteristics of virtual teams: a case study

Abstract: Organizations are encountering novel external environments requiring flexible structures. A number of organizations have used virtual teams to provide the customer responsiveness, human resource flexibility, and speed in project completion these environments demand. Virtual teams create significant communication challenges for its leaders and members. This research analyzed the communication technologies that the Customer Support Virtual Team (CST) of International Consulting Systems (ICS), the pseudonym for a Fortune 500 organization, uses to support team interaction, the degree to which ICS systems and culture supported CST, and finally, the CST members' mindset toward communication and the methods its leader used to create the trust required for effective team interaction. Interviews revealed that ICS mission, strategy, tasks, reward systems, and attitudes toward technology supported virtual team structure. CST members were provided a suite of robust technologies to facilitate interaction; however, they relied heavily on voice mail and a large number of team, project, and organizational databases supported by Lotus Notes to generate a common language that facilitated task completion.

Inertial and magnetic posture tracking for inserting humans into networked virtual environments

Abstract: Rigid body orientation can be determined without the aid of a generated source using nine-axis MARG (Magnetic field, Angular Rate, and Gravity) sensor unit containing three orthogonally mounted angular rate sensors, three orthogonal linear accelerometers and three orthogonal magnetometers. This paper describes a quaternion-based complementary filter algorithm for processing the output data from such a sensor. The filter forms the basis for a system designed to determine the posture of an articulated body in real-time. In the system the orientation relative to an Earth-fixed reference frame of each limb segment is individually determined through the use of an attached MARG sensor. The orientations are used to set the posture of an articulated body model. Details of the fabrication of a prototype MARG sensor are presented. Calibration algorithms for the sensors and the human body model are also presented. Experimental results demonstrate the effectiveness of the tracking system and verify the correctness of the underlying theory.

Toward transformative dialogue

Abstract: Drawing from a social constructionist theoretical orientation, and a range of congenial practices, we propose the concept of transformative dialogue which stresses relational responsibility, self-expression, affirmation, coordination, reflexivity, and the co-creation of new realities. We see conversational moves that accomplish these aims as highly promising; at the same time there is no attempt in the present article to suggest these as ultimate solutions to employ in situations of conflict. The present is an attempt to generate a potentially useful vocabulary rather than a strict set of rules for negotiating among incommensurate realities.

Fiscal Decentralization and Economic Growth

Abstract: This paper reviews the current knowledge on an issue of increasing policy interest: what impact fiscal decentralization has on economic growth. Fiscal decentralization may indeed have a direct impact on economic growth but the theoretical underpinnings for this relationship remain largely undeveloped. The absence of an adequate theoretical framework has undermined the validity of the empirical work on this subject. A fair summary of the empirical search for a direct relationship between fiscal decentralization and economic growth is that it remains an open question. Much less attention has been devoted in the literature to the indirect channels through which fiscal decentralization may affect economic growth, through the impact of fiscal decentralization on economic efficiency, the regional distribution of resources, and macroeconomic stability. This paper explorers the nature of these links and concludes with some thoughts and policy advice.

Active spacecraft potential control for Cluster - implementation and first results

Abstract: Electrostatic charging of a spacecraft modifies the distribution of electrons and ions before the particles enter the sensors mounted on the spacecraft body. The floating potential of magnetospheric satellites in sunlight very often reaches several tens of volts, making measurements of the cold (several eV) component of the ambient ions impossi- ble. The plasma electron data become contaminated by large fluxes of photoelectrons attracted back into the sensors. The Cluster spacecraft are equipped with emitters of the liquid metal ion source type, producing indium ions at 5 to 9 keV energy at currents of some tens of microampere. This current shifts the equilibrium potential of the spacecraft to moderately positive values. The design and principles of the operation of the instrument for active spacecraft poten- tial control (ASPOC) are presented in detail. Experience with spacecraft potential control from the commissioning phase and the first two months of the op- erational phase are now available. The instrument is oper- ated with constant ion current for most of the time, but tests have been carried out with varying currents and a "feedback" mode with the instrument EFW, which measures the space- craft potential . That has been reduced to values according to expectations. In addition, the low energy electron measure- ments show substantially reduced fluxes of photoelectrons as expected. The flux decrease in photoelectrons returning to the spacecraft, however, occurs at the expense of an en-

Observations of nonlinear internal waves on the outer New England continental shelf during the summer Shelfbreak Primer study

Abstract: Observations are presented of nonlinear internal waves on the outer New England continental shelf during the summer Shelfbreak Primer study conducted between July 26 and August 5, 1996. Current and temperature measurements were made with an upward looking acoustic Doppler current profiler (ADCP) located on the 147 m isobath near the shelfbreak and three vertical thermistor moorings located upshelf. Data from the ADCP and two nearby thermistor chains show energetic internal tides propagating at roughly 0.9 m s 21 to the north-northwest, nearly perpendicular to the local topography with 10 -15 cm s 21 horizontal currents and 15-30 m vertical displacements. These waves evolve rapidly within a 5.8 km range into an undular internal tidal bore. Cross-isobath barotropic tidal currents, responsible for generating the internal tides are in the 5-12 cm s 21 range. The bore formation is highly variable. There is evidence of a correlation between internal tide steepening and a shelfbreak front jet orientation that is oppositely directed to the internal tide propagation. There is no correlation between steepening and the jet's vertical shear. Statistics of the undular bores show rms travel time fluctuations from 0.8 to 1.7 hours and average tidal bore durations from 12 to 9 hours. The average undular bore speed is 0.9 m s 21 , with an rms fluctuation of 0.4 m s 21 . The number of high-frequency waves in the bore varies from 0 to 8 near the shelfbreak and increases to 30 waves 26.7 km upshelf. The observed distribution function of temporal spacing between high-frequency internal waves is spread between 4 and 20 min.

Command, control, and navigation experimental results with the NPS ARIES AUV

Abstract: Provides an overview of the Naval Postgraduate School ARIES autonomous underwater vehicle and its control and navigation. An attempt is made to highlight its current operational capabilities and provide a description of future enhancements for greater mission utility and flexibility. An overview of the vehicle design along with descriptions of all major hardware components and sensors is given. A major discussion of the implementation of a modular, multirate, multiprocess software architecture for the ARIES is provided. The architecture is designed to operate using either a single computer processor or two independent, cooperating processors linked through a network interface for improved load balancing. A dual computer implementation is presented since each processor assumes different tasks for mission operation. Also included is a section on the underwater navigation method using a real-time extended Kalman filter that fuses all sensor data and computes the real time position, orientation and velocity. Experimental results for navigational accuracy using a DGPS/IMU/Doppler-aided navigation system are presented with DGPS pop-up maneuvers. Navigational accuracy is a requirement for the use of ARIES as a mobile communications network node. This work provides some examples of missions possible with such a node and the current state of its command and control system.

On the relationship between Indian Ocean Sea Surface Temperature and Asian summer monsoon

Abstract: Indian Ocean SST has been thought to play a weaker role in Indian summer monsoon rainfall than does the equatorial eastern Pacific SST. In this study we show that on the tropical biennial oscillation (TBO, 2–3 year) time scale the Indian monsoon rainfall has significant positive correlations with the Indian Ocean SST and moisture flux transport in the preceding winter and spring. The effect of this SST influence is quite different from the remote forcing of the Indian monsoon rainfall by the eastern Pacific SST, which is more dominant on the El Nino-Southern Oscillation (ENSO, 3–7 year) time scale. We conclude that while the eastern Pacific SST and the Eurasian land temperature both may affect the monsoon on the ENSO time scale, they are not important on the TBO time scale. Our results support the tropical and local feedback theories of TBO that this most important component of the monsoon variation is largely influenced by the Indian Ocean SST and interactions within the tropical atmosphere-ocean system (Chang and Li, Nichols).

Quality of security service

Abstract: : We examine the concept of security as a dimension of Quality of Service in distributed systems. Implicit to the concept of Quality of Service is the notion of choice or variation. Security services also offer a range of choice both from the user perspective and among the underlying resources. We provide a discussion and examples of user-specified security variables and show how the range of service levels associated with these variables can support the provision of Quality of Security Service, whereby security is a constructive network management tool rather than a performance obstacle. We also discuss various design implications regarding security ranges provided in a QoS-aware distributed system.

Agent-Based Supply Chain Integration

Abstract: Supply chain management represents a critical competency in today's fast-paced, global business environment. However, in the current transition from EDI to Web-based supply chain technologies, much of the capability for process integration is being lost. And the integration of buyer and seller supply chain processes is critical for speed and responsiveness in today's hypercompetitive product and service markets. Intelligent agent technology offers the potential to overcome many limitations of current supply chain technologies. This paper presents intelligent supply chain agents that represent and autonomously conduct business on behalf of product users, buyers and vendors. We classify and present numerous extant agent applications and extend a technological framework to compare and contrast intelligent agents with other classes of information technology. We then describe an agent-based supply chain process design, along with its developmental techniques, and the structure and behavior of an agent federation used for integration in a major enterprise. We present results of this exploratory research in terms of technical feasibility and process performance in the enterprise context. This work is novel in that it integrates process-level knowledge from operational enterprises with distributed agent technologies. And it makes a contribution by demonstrating how agent-based supply chain integration can be effected along a large-scale, operational, inter-organizational process.

Enhancement of the inertial navigation system for the Morpheus autonomous underwater vehicles

Abstract: This paper presents the design and development of an enhanced inertial navigation system that is to be integrated into the Morpheus autonomous underwater vehicle at Florida Atlantic University. The inertial measurement unit is based on the off-the-shelf Honeywell HG1700-AG25 3-axis ring-laser gyros and three-axis accelerometers and is aided with ground speed measurements obtained using an RDI Doppler-velocity-log sonar. An extended Kalman filter has been developed, which fuses together asynchronously the inertial and Doppler data, as well as the differential Global Positioning System positional fixes whenever they are available. A complementary filter was implemented to provide a much smoother and stable attitude estimate. Thus far, preliminary study has been made on characterizing the inertial navigation system-based navigation system performance, and the corresponding results and analyzes are provided.

Rossby Waves in Zonally Opposing Mean Flow: Behavior in Northwest Pacific Summer Monsoon

Abstract: The interactions between monsoon circulations and tropical disturbances in the Northwest Pacific, where the low-level mean flow is westerly in the west and easterly in the east, are studied with a barotropic model. The authors’ model results suggest that the scale contraction by the confluent background flow, the nonlinear dynamics, the β effect, and the large-scale convergence are important for the energy and enstrophy accumulation near the region where the zonal flow reverses. The energy/enstrophy accumulation can be maintained with a continuous Rossby wave emanation upstream. The largest accumulation occurs when the emanating zonal wavelength is around 2000 km. Longer Rossby waves experience less scale contraction and nonlinear effects while shorter Rossby waves cannot hold a coherent structure against dispersive effects. The nonlinear energy/enstrophy accumulation mechanism is significantly different from previous linear energy accumulation theories. In the linear theories this is primarily a...

Wake-Vortex Eddy-Dissipation Model Predictions Compared with Observations

Abstract: We describe the latest version of a wake-vortex eddy-dissipation model devised by T. Sarpkaya and to compare its predictions with lidar observations obtained at Memphis and Dallas/Fort Worth airports. The model simulates the evolution of aircraft-generated trailing vortices in an atmospheric environment defined by vertical profiles of potential temperature, eddy-dissipation rate, and crosswind. Visual and quantitative comparisons of the time histories of altitude, circulation, and lateral position of predicted and measured vortices are presented

Why Power Indices and Coalition Formation

Abstract: This introductory note discusses the main arguments that motivate the growing interest in power indices and the theory of coalition formation that also determine the selection of contributions to this volume. The main arguments are those of substantial growth in the application of power indices to political institutions, especially the European Union, the intensive discussion of the monotonicity properties of various indices, and the probabilistic interpretation of power, coalition formation, and power measures.

Unconditionally secure communications over fading channels

Abstract: In this paper, we propose a novel method for two communicates to exchange a secret over a public wireless fading channel. Unlike conventional computationally secure public key methods, this technique is information theoretic and unconditionally secure provided that a component of the reciprocal channel fading over time between the two communicates is statistically independent with the channel fading from either communicate to the eavesdropper. This technique may be particularly well suited to secure tactical mobile communications. A simple protocol suitable for a lognormal shadowed fading channel is described and its key exchange rate is derived.

A network layer protocol for UANs to address propagation delay induced performance limitations

Abstract: This paper provides a description of a novel network layer protocol for underwater acoustic networking (UAN) that provides a mechanism for network control and management enabling the implementation of responsive, self-configuring, adaptable, and scalable networks whose performance are predictable. The protocol draws from the demonstrated efficiencies of multi-protocol labeled switching, dynamic source routing, and multi-constraint based resource allocation schemes. The paper describes the expected benefits of establishing full duplex functionality between network nodes and presents some of the preliminary simulation findings regarding the viability of autonomously determining the network topology utilizing the full duplex node connections.

The break-up of Indonesia? Nationalisms after decolonisation and the limits of the nation-state in post-cold war Southeast Asia

Abstract: One noteworthy feature of the political crisis in Indonesia, which followed the Asian financial crisis of 1997 was the speed with which the collapse of the Suharto government was subsumed by a wider crisis of the Indonesian nation-state. One aspect of this crisis is the strengthening of secessionist movements in several regions of Indonesia, calling into question the country's national boundaries, themselves a legacy of the Dutch colonial era. This article examines the tensions in the nation-building efforts of the Indonesian state by focusing on the three territories where secessionist movements have been strongest: East Timor, which has already successfully broken away from Indonesia, and Irian Jaya and Aceh, where long-standing secessionist movements experienced significant growth in the aftermath of the resignation of President Suharto on 21 May 1998. Our analysis emphasises that these secessionist movements arose in direct response to the ways in which the Indonesian state, especially during the Suha...

Simulations of the Transformation Stage of the Extratropical Transition of Tropical Cyclones

Abstract: The physical mechanisms associated with the transformation stage of the extratropical transition of a tropical cyclone are simulated with a mesoscale model using initial environmental conditions that approximate the mean circulations defined by Klein et al. The tropical cyclone structural changes simulated by the U.S. Navy Coupled Ocean–Atmosphere Model Prediction System mesoscale model during the three steps of transformation compare well with available observations. During step 1 of transformation when the tropical cyclone is just beginning to interact with the midlatitude baroclinic zone, the main environmental factor that affects the tropical cyclone structure appears to be the decreased sea surface temperature. The movement of the tropical cyclone over the lower sea surface temperatures results in reduced surface heat and moisture fluxes, which weakens the core convection and the intensity decreases. During step 2 of transformation, the low-level temperature gradient and vertical wind shear ...

Convergence, stability, and variability of shallow water acoustic predictions using a split-step fourier parabolic equation model

Abstract: The Shallow Water Acoustic Modeling (SWAM'99) Workshop was organized to examine the ability of various acoustic propagation models to accurately predict sound transmission in a variety of shallow water environments designed with realistic perturbations. In order to quantify this, tests of reciprocity, convergence, and stability must be considered. This paper presents the results of an established parabolic equation model based on the split-step Fourier algorithm. The test cases examined in this paper include a simple isospeed water column over a flat bottom with geoacoustic parameter variations, a randomly sloping bottom with geoacoustic parameter variations, and a canonical shallow water profile perturbed by internal waves over a flat, homogeneous bottom. Source configurations were generally held constant but numerous single frequency and broadband runs were performed. Model testing is emphasized with specific criteria for accurate solutions being specified. Random perturbations are added to one test case to examine the influence of environmental uncertainty on the details of the propagation. The results indicate that point-wise accurate solutions to the acoustic field in shallow water cannot be achieved beyond a few kilometers. This is partly due to the inaccuracies of the split-step Fourier algorithm employed in these shallow water scenarios and the treatment of the bottom interface boundary conditions, but also due to the inherent variability caused by uncertain environmental specification. Thus, more general features of the acoustic field should be emphasized at longer ranges.

Investigation of logistic regression as a discriminant of software quality

Abstract: Investigates the possibility that logistic regression functions (LRFs), when used in combination with Boolean discriminant functions (BDFs), which we had previously developed, would improve the quality classification ability of BDFs when used alone; this was found to be the case. When the union of a BDF and LRF was used to classify quality, the predictive accuracy of quality and inspection cost was improved over that of using either function alone for the Space Shuttle. Also, the LRFs proved useful for ranking the quality of modules in a build. The significance of these results is that very high-quality classification accuracy (1.25% error) can be obtained while reducing the inspection cost incurred in achieving high quality. This is particularly important for safety-critical systems. Because the methods are general and not particular to the Shuttle, they could be applied to other domains. A key part of the LRF development was a method for identifying the critical value (i.e. threshold) that could discriminate between high and low quality, and at the same time constrain the cost of inspection to a reasonable value.

Coordinated Control of Multisatellite Systems

Abstract: The problem of formation and reconŽ guration of multiple microsatellite systems is addressed A control scheme called the perceptive frame is adopted that integrates the decentralized feedback of each satellite with online sensor information to achieve the goal of formation keeping and intersatellite coordination The proposed design algorithm has the advantage of relative position keeping and easy formation reconŽ guration

Adrift in the Beaufort Gyre: A Model Intercomparison

Abstract: Output from six regional sea ice-ocean climate model simulations of the arctic seas is compared to investigate the models' ability to accurately reproduce the observed late winter mean sea surface salinity. The results indicate general agreement within the Nordic seas, strong differences on the arctic continental shelves, and the presence of a climate drift that leads to a high salinity bias in most models within the Beaufort Gyre. The latter is highly sensitive to the wind forcing and to the simulation of freshwater sources on the shelves and elsewhere.