Showing papers by "Naval Postgraduate School published in 1983"
TL;DR: In this article, a digital filter with discrete coefficient values selected from the powers-of-two coefficient space is designed using the methods of integer programming, and the frequency responses obtained are shown to be superior to those obtained by simply rounding the coefficients.
Abstract: FIR digital filters with discrete coefficient values selected from the powers-of-two coefficient space are designed using the methods of integer programming. The frequency responses obtained are shown to be superior to those obtained by simply rounding the coefficients. Both the weighted minimax and the weighted least square error criteria are considered. Using a weighted least square error criterion, it is shown that it is possible to predict the improvement that can be expected when integer quadratic programming is used instead of simple coefficient rounding.
451 citations
TL;DR: In this article, the authors report on the socialization practices most available to new employees and the extent to which these practices are seen by newcomers as being helpful in becoming effective organizational members.
Abstract: This study reports on the socialization practices most available to new employees and the extent to which these practices are seen by newcomers as being helpful in becoming effective organizational members. The results showed that socialization practices are differentially available to newcomers, and perceptions of their helpfulness vary. The helpfulness of various socialization practices as reported by newcomers appears to affect their feelings of subsequent job satisfaction and commitment.
423 citations
TL;DR: In this article, the remaining unquantized coefficients of a FIR linear phase digital filter when one or more of the filter coefficients takes on discrete values are optimized using the least square response error.
Abstract: An efficient method optimizing (in the least square response error sense) the remaining unquantized coefficients of a FIR linear phase digital filter when one or more of the filter coefficients takes on discrete values is introduced. By incorporating this optimization method into a tree search algorithm and employing a suitable branching policy, an efficient algorithm for the design of high-order discrete coefficient FIR filters is produced. This approach can also be used to design FIR filters on a minimax basis. The minimax criterion is approximated by adjusting the least squares weighting. Results show that the least square criteria is capable of designing filters of order well beyond other approaches by a factor of three for the same computer time. The discrete coefficient spaces discussed include the evenly distributed finite wordlength space as well as the nonuniformly distributed powers-of-two space.
240 citations
TL;DR: In this paper, the power-law wind dependence of the low elevation concentration of droplets larger than 8pm radius was determined to be similar to the wind dependent of whitecap cover, with I. vaiues of 3.23 and 3-31 resulting from the respective application of the robust bi-weight fitting technique.
Abstract: SUMMARY Low elevation aerosol spectra, ocean whitecap cover and 10m wind speeds measured during the 1978 JASIN experiment have been inter-related and compared with previously published observations. The positive dependence of aerosol concentration upon whitecap cover was found to increase with droplet radius reflecting the expected higher correlation of the concentration of larger droplets, which have shorter effective residence time in the marine atmospheric boundary layer, with the immediate whitecap cover, which reflects the instantaneous rate of aerosol generation at the sea surface. The power-law wind dependence, Ui, of the low elevation concentration of droplets larger than 8pm radius was determined to be similar to the wind dependence of whitecap cover, with I. vaiues of 3.23 and 3-31 resulting from the respective application of the robust bi-weight fitting technique. This observation is consonant with an aerosol generation model in which the instantaneous rate of production is simply proportional to the immediate whitecap cover. The large droplet end of the JASIN low elevation aerosol spectrum is seen to undergo a marked enhancement when the wind speed exceeds IOms-'. This is a consequence of the onset at that speed of supplementary droplet production via the mechanical disruption of wave crests. The observed growth, with increasing wind speed, in the disparity in amplitude of near-sea-surface and near-cloud-base aerosol spectra is in part a consequence of the fact that the larger droplets, produced in relative abundance at the higher wind speeds, fall out before they can be mixed effectively through the boundary layer.
226 citations
TL;DR: This work is supported in part by the National Science Foundation under Grant NSF-ENG-79-01438 and NSF -79-10825 and by the Office of Naval Research under Grant NR-42-284 and NR- 42-469.
Abstract: supported in part by National Science Foundation under
Grant NSF-ENG-79-01438 and NSF-ENG-79-10825; and by the Office of Naval
Research under Grant NR-42-284 and NR-42-469.
202 citations
TL;DR: In this article, specific implementations of the finite impulse response (FIR) block adaptive filter in the frequency domain are presented and some of their important properties are discussed, and the time-domain block adaptive filtering is shown to be equivalent to the frequency-domain adaptive filtering, provided data sectioning is done properly.
Abstract: Specific implementations of the finite impulse response (FIR) block adaptive filter in the frequency domain are presented and some of their important properties are discussed. The time-domain block adaptive filter implemented in the frequency domain is shown to be equivalent to the frequency-domain adaptive filter (derived in the frequency domain), provided data sectioning is done properly. All of the known time- and frequency-domain adaptive filters [1]-[12], [16]-[18] are contained in the set of possible block adaptive filter structures. Thus, the block adaptive filter is generic and its formulation unifies the current theory of time- and frequency-domain FIR adaptive filter structures. A detailed analysis of overlap-save and overlap-add implementations shows that the former is to be preferred for adaptive applications because it requires less computation, a fact that is not true for fixed coefficient filters.
197 citations
TL;DR: In this paper, the authors examined the relevant literature and developed a model of defense and economic growth that explicitly incorporates resource constraints and found that relatively poor countries tend to cut back high-growth development expenditures in favor of maintaining defense programs, while relatively rich countries are much less likely to abandon development expenditures given a constant level of defense preparedness.
Abstract: : Studies of the effect that defense spending has had on economic growth in less-developed countries have produced rather mixed results. We contend that this is because these studies have failed to take into account the relative financial constraints faced by individual countries. In an extension of the seminal work by Emile Benoit on defense spending and its effect on economic growth, I we hypothesize that relatively poor countries tend to cut back high-growth development expenditures in favor of maintaining defense programs, while relatively rich countries are much less likely to abandon development expenditures given a constant level of defense preparedness. Thus, we should expect a negative relationship between defense and growth in the poorer countries, but a positive relationship in the richer countries. In this article, we examine the relevant literature, and develop a model of defense and economic growth that explicitly incorporates resource constraints. The results of the cluster analysis that was used to group the sample of countries into a richer and poorer group are presented. Finally, the results of the within-group regressions are presented.
135 citations
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TL;DR: This paper contrasts the notion of strategy that has developed in the field of business policy over the past decade or so with the conceptions that prevail in other loosely related fields--most notably the fields of military practice and of futures research.
115 citations
TL;DR: In this article, experiments were conducted with three delta wings and two rectangular wings to investigate the evolution of trailing vortices in stratified and unstratified water, and the trajectories were determined as a function of the normalized time V0t/b0, stratification parameter Nb0/V0 and an effective vortex-core size re/b 0.
Abstract: Experiments were conducted with three delta wings and two rectangular wings to investigate the evolution of trailing vortices in stratified and unstratified water. The vortex trajectories were determined as a function of the normalized time V0t/b0, stratification parameter Nb0/V0 and an effective vortex-core size re/b0. The results have shown that the vortices rise only to a finite height as they decay gradually at first and rapidly thereafter under the influence of turbulence, sinusoidal instability, and core bursting. The effect of stratification is to reduce the lifespan of vortices and the maximum height attained by them.
114 citations
TL;DR: An iterative Forward And Backward FAB algorithm applicable to the problem of computing optimal search plans when the target's motion is modeled by a discrete space and time Markov chain is proposed and studied.
Abstract: We propose and study an iterative Forward And Backward FAB algorithm applicable to the problem of computing optimal search plans when the target's motion is modeled by a discrete space and time Markov chain. This paper generalizes the class of objective functions to which the method applies.
104 citations
TL;DR: In this article, the surface flux can be inferred from measuremerits of the rate of change of aerosol densities and changes in the height of the marine boundary layer using data from CEWCOM-78.
Abstract: The rate of production of sea water droplets by bubble bursting at the ocean surface is very difficult to measure directly. Laboratory simulations are also difficult. However, the surface flux can be inferred from measuremerits of the rate of change of aerosol densities and changes in the height of the marine boundary layer. Data from CEWCOM-78 have been analyzed to produce the aerosol surface flux volume spectrum from 0.8 to 15 pm radius at a wind speed of 9 m s -1 . Using this flux spectrum and equilibrium aerosol spectra from JASIN. flux spectra are calculated for wind speeds from 6 to 18 m s -1 . DOI: 10.1111/j.1600-0889.1983.tb00005.x
TL;DR: In this article, two types of atmospheric response to steady tropical forcing are studied by an eigenmode analysis using a linearized model with constant mean wind on an equatorial β-plane.
Abstract: Using a linearized model with constant mean wind on an equatorial β-plane, two types of atmospheric response to steady tropical forcing are studied by an eigenmode analysis. The first type is the less rotationally trapped “barotropic” motions which show some of the characteristics of the teleconnection patterns observed by Bjerknes (1966) and Horel and Wallace (1981). The second type is the more rotationally trapped, warm-core, deep baroclinic motions which resemble the Walker circulations. The analysis reveals several important inadequacies in previous modeling studies and provides a relatively comprehensive explanation of the dynamics of both types of motions. A vertical normal mode consideration shows that the barotropic-type motions are difficult to excite by internal beating. Surface heating, which has been neglected in many previous numerical modeling studies, is found to be important in directly forcing this type of motion. Furthermore, the possible contribution by large equivalent depth i...
TL;DR: In this article, the effects of transformation cycling between the parent and martensite phases of selected Cu-Zn-Al: alloys were studied using differential scanning calorimetry.
Abstract: The effects of transformation cycling between the parent (P) and martensite (M) phases of selected Cu-Zn-Al: alloys were studied. Using differential scanning calorimetry it was observed that the martensite start temperature, Ms, progressively shifts upward with cycling. Also, the proportion of the microstructure actually undergoing P↔M transformation decreases. Transmission electron microscope observations reveal dislocation substructures generated by martensite transformation and reversion.
TL;DR: In this paper, cold surges were identified from shipboard data over the South China Sea and characterized an increase in the surface northerly wind and a surface pressure differential between Hong Kong and 30 deg N, 115 deg E. The data were taken twice a day, and included the total wind field, the computed rotational and divergent winds, the velocity potential, and the streamfunction.
Abstract: The FGGE/winter-Monex wind data from 850 and 200 mb are used to analyze the short-term teleconnections over the tropical and midlatitude Pacific and monsoonal surges in the winter of 1978-79. The data were taken twice a day, and included the total wind field, the computed rotational and divergent winds, the velocity potential, and the streamfunction. Cold surges were identified from shipboard data over the South China Sea and characterized an increase in the surface northerly wind and a surface pressure differential between Hong Kong and 30 deg N, 115 deg E. Midlatitude baroclinic disturbances triggered the cold surges, which displayed intensities dependent on the strength of the midlatitude anticyclogenesis and the intensity of the East Asia local Hadley cell. Fluctuations in the 200 mb jet streak over Japan indicated changes in eddy behavior over the North Pacific and the intensity of the East Asia local Hadley cell circulation and tropical convection. It was concluded that midlatitude synoptic systems could force equatorial convection that produces remote midlatitude responses.
TL;DR: In this article, 13 profiles of the rate of viscous dissipation of turbulent kinetic energy were made over the continental slope off Vancouver Island between 12 and 14 May 1980 in conjunction with CTD and moored current-meter observations.
Abstract: Thirteen profiles of the rate of viscous dissipation of turbulent kinetic energy &epsi¯ were made over the continental slope off Vancouver Island between 12 and 14 May 1980 in conjunction with CTD and moored current-meter observations. Systematic variability was observed in the vertical but not in the horizontal direction. Above 200 m depth numerous salt-stabilized temperature inversions were seen and dissipation rates were significantly larger than below 200 m. Dissipation rates below 200 m are the lowest ever reported and coincide with a low level of energetics revealed by the current meter moorings. Comparison with the Garrett-Munk internal wave spectrum indicates an e-folding decay time of internal wave energy of ∼50 days at depths below 200 m.
TL;DR: In this paper, surface pressure, temperature, dew point and wind data over the South China Sea and vicinity during Winter MONEX were examined to determine the timing of the passage of cold surges at various reporting stations.
Abstract: The surface pressure, temperature, dew point and wind data over the South China Sea and vicinity during Winter MONEX are examined to determine the timing of the passage of cold surges at various reporting stations. It is found that for more than half of the surge cases during Winter MONEX, a surge occurs in two stages separated by a time interval of several hours to approximately one day. The first stage is often characterized by a significant rise in pressure, while the second stage by a sharp decrease in dew point temperature. Freshening of surface winds may accompany either or both stages. The time separation between the two stages is relatively short at the upstream stations but generally long at the downstream stations. The second stage is associated with a frontal passage. On the other hand, the first stage is not clearly associated with any significant synoptic events. From its very fast propagation speed which increases with an inferred depth scale, and an increase in the local cross-isob...
TL;DR: In this paper, the authors obtained weekly EOFA charts of the Gulf Stream from the US Navy's weekly IR imagery based on satellite IR imagery for the period from 1975 to 1978.
Abstract: Weekly Gulf Stream paths within 1000 km downstream of Cape Hatteras were obtained for 1975–78 from the Navy's weekly EOFA charts based on satellite IR imagery. They displayed two dominant meander modes: first, a standing meander energetic over periods between 4 months and at least 4 years; and second. down-stream-propagating meanders that were most energetic at periods of several weeks. The long-period standing meander was confined between nodes located at the separation point near Cape Hatteras (i.e., where the Stream's mean path turns seaward) and at a point about 600 km farther downstream. The rms amplitude was 36 km at the antinode. The amplitude of propagating meanders increased rapidly in the first 200 km downstream of the separation point, where the capture of warm-core eddies was common. Farther down-stream, the predominant meanders had a wavelength averaging 330 km, a period averaging 1.5 month, a phase speed averaging 8 cm s−1, a downstream group speed averaging 17 cm s−1, and downstrea...
TL;DR: In this paper, a technique for designing recursive and non-recursive two-dimensional digital filters by the application of a complex transformation to a one-dimensional low-pass filter is presented.
Abstract: This paper develops a technique for designing recursive and nonrecursive two-dimensional digital filters by the application of a complex transformation to a one-dimensional low-pass filter. A set of transformed filters is presented. The appropriate combination of these filters produces zero-phase fan filters. The advantage of such an approach is that the resulting fan filters are inherently stable and no optimization is needed. Several examples are presented for both finite impulse response (FIR) and infinite impulse response (IIR) fan filters and quadrant fan filters. The paper also includes implementation techniques using the properties of finite area arrays which reduce both computational and storage requirements compared with conventional implementations.
01 Jan 1983
TL;DR: Satellite infrared images of the eastern North Pacific show surface thermal features which appear to be mesoscale eddies and fronts within the California Current and coastal upwelling zone.
Abstract: Satellite infrared (IR) images of the eastern North Pacific show surface thermal features which appear to be mesoscale eddies and fronts within the California Current and coastal upwelling zone. Coordinated satellite and shipboard measurements show that some of these are produced by interaction between the California Current and wind-induced upwelling near points and capes along the coastal boundary. The process of coastal upwelling as viewed from space is unlike the simple structure expected from classical concepts and may develop a cyclonic circulation, an anticyclonic circulation, or surface flows which extend far offshore as giant cold water plumes embedded in the California Current. Observations of a cyclonic upwelling system off Point Sur, California, show that these recurrent injections of nutrient-rich, cold waters produce the same distinctive structure in the nutrient field. When present, microplankton concentrate in the sharp thermal and nutrient fronts that define these systems. The combined effect of the distinctive advective process and redistribution of nutrients is a significant factor in determining the distribution of primary production and biological patchiness along the coast and in the California Current system. Since ships are too slow to synoptically study these large and rapidly changing upwelling systems, phytoplankton distribution and the nutrient structure of the sea surface is inferred from satellites. By calibrating satellite infrared data against in situ nutrient measurements, sea surface nutrient maps can be produced so that estimates of the true nutrient distribution and potential sites of biological activity can be made. Satellite ocean color imagery shows this relationship between chlorophyll-biomass blooms and sharp nutrient gradients. This upwelling center appears to operate like a “natural chemostat.” Such recurrent upwelling at favored locations along the coastal boundary may be reflected in the sediment record.
TL;DR: In this article, computer simulations of ion-bombardment events which recrystallize the target demonstrate pit formation at 1.0 keV, where atoms are ejected from the first two target layers in the pit region.
Abstract: Computer simulations of ion-bombardment events which recrystallize the target demonstrate pit formation at 1.0 keV. Atoms are ejected from the first two target layers in the pit region. The remainder of the pit is created by replacement-collision sequences. Linear-cascade and spike-regime events are dynamically indistinguishable. © 1983 The American Physical Society.
TL;DR: In this article, a two part review covers experiments examining the effects of blade tip gap encountered in turbomachines and the methods by which the synthesized data are currentl used in turbine turbomachine design and analysis.
TL;DR: In this article, two cases of summer monsoon depressions in the vicinity of the Bay of Bengal are analyzed to study the importance of the baroclinic mechanism, and both cases show a barocliic structure with well-defined warm and cold sectors, the latter being situated to the east of the former in a region where the thermal wind is easterly throughout the troposphere.
Abstract: Two cases of summer monsoon depressions in the vicinity of the Bay of Bengal are analyzed to study the importance of the baroclinic mechanism. Both cases show a baroclinic structure with well-defined warm and cold sectors, the latter being situated to the east of the former in a region where the thermal wind is easterly throughout the troposphere. In a developing depression, the geopotential and the temperature fields differ in phase such that warm advection from the north occurs to the west of the depression center and cold advection from the south to the east. There is also strong convergence to the west and divergence to the east of the depression center in the lower troposphere, and vice versa in the upper troposphere. Thus a divergent secondary circulation exists in the zonal-vertical plane with warm air rising to the west and cold air sinking to the east. Marked increases in upward motion and relative divergence (divergence at 200 mb minus divergence at 850 mb) in the southwest sector occur...
01 Jan 1983
TL;DR: A nonlinear optimization algorithm is developed which combines the best features of the Method of Feasible Directions and the Generalized Reduced Gradient Method and finds that the sensitivity of the optimum design to changes in the problem parameters can be obtained using this method without the need for second derivatives or Lagrange multipliers.
Abstract: A nonlinear optimization algorithm is developed which combines the best features of the Method of Feasible Directions and the Generalized Reduced Gradient Method. This algorithm utilizes the direction-finding sub-problem from the Method of Feasible Directions to find a search direction which is equivalent to that of the Generalized Reduced Gradient Method, but does not require the addition of a large number of slack variables associated with inequality constraints. This method provides a core-efficient algorithm for the solution of optimization problems with a large number of inequality constraints. Further optimization efficiency is derived by introducing the concept of infrequent gradient calculations. In addition, it is found that the sensitivity of the optimum design to changes in the problem parameters can be obtained using this method without the need for second derivatives or Lagrange multipliers. A numerical example is given in order to demonstrate the efficiency of the algorithm and the sensitivity analysis.
TL;DR: In this paper, the amplitude and steepness of broad smooth-sided jets are modeled by a top-hat pattern and an approximate solution is found for linear waves, based on conservation of wave action and vertical averaging.
Abstract: Variations in wave amplitude and steepness across current jets have been described for broad smooth-sided jets. Here, narrow jets are modelled by a top-hat pattern; an approximate solution is found for linear waves, based on conservation of wave action and vertical averaging. The results join remarkably well to those for a broad cosine-shaped jet (cf. McKee 1975). For jet widths less than about a third of a wavelength, there is little change in amplitude ; the enhancement predicted by a WKB analysis is suppressed owing to interference with reflections from the far side of the jet. For directional spectra not too different from cos2 8 , some suppression occurs near the middle of jets of all scales, owing to exclusion of the glancing wave components by reflection from the near side ; this suppression can be significant for jets more than a wavelength wide. For monochromatic waves, maximum amplitudes occur some distance outside the jet owing to interference; the net reflection appears to have a positive phase shift along the near caustic of about 1 cycle.
TL;DR: In this article, a computer simulation of ion-bombardment events has been extended to coalesce and recrystallise the target, so that the surface damage created when a single ion strikes a metal surface can now be studied directly.
01 Jan 1983
TL;DR: In this article, the authors present the capabilities of the ADS-1 program and demonstrate its application to structural synthesis, which solves the general nonlinear constrained optimization problem in the standard form at each level of the optimization process.
Abstract: Today, numerous programs are available which may be coupled with finite element analysis or other analysis techniques to perform the optimization function in the solution of structural synthesis problems. However, most of these codes include only one or two algorithms and many have not been tested on problems of significant size and complexity. There is, therefore, a need for a reliable, general-purpose, publicly available code, containing a variety of modern algorithms for use in structural synthesis as well as general engineering design. The ADS-1 program (Automated Design Synthesis: Version 1) was written in response to this need. The present investigation has the objective to present the capabilities of the ADS program and to demonstrate its application to structural synthesis. The ADS program solves the general nonlinear constrained optimization problem in the standard form. At each level of the optimization process, several options are available.
TL;DR: An important transformation of the battle's time scale is introduced that not only simplifies the force-level equations, but also shows that relative fire effectiveness and intensity of combat are the only two weapon-system parameters determining the course of such variable-coefficient Lanchester-type combat.
Abstract: This paper introduces important new functions for analytic solution of Lanchester-type equations of modem warfare for combat between two homogeneous forces modeled by power attrition-rate coefficients with "no offset." Tabulations of these Lanchester-Clifford-Schlafli or LCS functions allow one to study this particular variable-coefficient model almost as easily and thoroughly as Lanchester's classic constant-coefficient one. LCS functions allow one to obtain important information in particular, force-annihilation prediction without having to spend the time and effort of computing force-level trajectories. The choice of these particular functions is based on theoretical considerations that apply in general to Lanchester-type equations of modern warfare and provide guidance for developing other canonical functions. Moreover, our new LCS functions also provide valuable information about related variable-coefficient models. Also, we introduce an important transformation of the battle's time scale that not only simplifies the force-level equations, but also shows that relative fire effectiveness and intensity of combat are the only two weapon-system parameters determining the course of such variable-coefficient Lanchester-type combat.
TL;DR: In this paper, an analysis of the radiative transfer processes in the atmosphere suggests that the ratio between the diffuse radiance flux and the directly transmitted flux may be a useful parameter for investigating the variation of atmospheric optical depth.
TL;DR: In this paper, Cerenkov radiation is calculated for electron beams which exceed the velocity of radiation in a nondispersive dielectric medium, and the electron beam is assumed to be bunched as emitted from a traveling-wave accelerator.
Abstract: Cerenkov radiation is calculated for electron beams which exceed the velocity of radiation in a nondispersive dielectric medium. The electron beam is assumed to be bunched as emitted from a traveling-wave accelerator, and the emission region is assumed to be finite. Predictions include (a) emission at harmonics of the bunch rate, (b) coherence of radiation at low frequencies, (c) smearing of the emission angle for finite emission regions, and (d) explicit evaluation of the power spectrum in terms of bunch dimensions. The results apply to microwave emission from fast electrons in air or other dielectrics.