Showing papers by "Naval Postgraduate School published in 1972"
TL;DR: In this paper, observations are available to show that, early in the hurricane season, there are varying initial conditions in the Gulf of Mexico which could lead to significantly different total heat exchanges.
Abstract: It has been demonstrated that a large input of energy from the ocean is necessary to establish and maintain hurricane force winds over the sea. However, there has been no suitable data which could serve as a basis for calculating this input. Now, observations are available to show that, early in the hurricane season, there are varying initial conditions in the Gulf of Mexico which could lead to significantly different total heat exchanges. The sea can provide some seven days of energy flow into a hurricane at some times and at some locations, but less than one day in others depending upon the amount of heat initially available in the Gulf waters. In the four summers represented by the data, a quantity defined as hurricane heat potential was found to vary from a low of 700 cal cm−2 column north of Yucatan to a high of 31,600 in the central east Gulf. Synoptic data on hurricane heat potential, if made regularly available to forecasters, might serve as a basis for improved forecasts of changes in In...
295 citations
TL;DR: Experimental thermal-conductivity data were obtained on the following in-vitro human organs: liver, kidney, heart, spleen, whole brain, brain gray matter, and brain white matter and three nondimensional groups for time, temperature, and blood flow emerge.
Abstract: A small needle-like probe has been developed for the determination of the thermal conductivity of either in-vitro or in-vivo tissue. This probe consists of a copper cylinder having a diameter of 1.5 mm and a length of 22.5 mm. Constantan and copper leads are attached to the center and top of the cylinder, respectively, and as a consequence the probe acts as a thermocouple. The distinguishing characteristic of this probe is that when it is suddenly embedded into a medium at a different temperature, the duration of its temperature–time response is such that it can be related to the thermal properties of the medium. This is accomplished by a match with an analytically determined response curve which accounts for metabolic heat generation, blood flow, and conductive effects. By nondimensionalizing the governing equations for the probe–tissue system, three nondimensional groups for time, temperature, and blood flow emerge. The results of a parametric study of these effects are presented in tabular form. Initially, the probe technique was used to determine the thermal conductivity of a 1 percent agar–water mixture and the results were within 5 percent of water. Subsequently, experimental thermal-conductivity data were obtained on the following in-vitro human organs: liver, kidney, heart, spleen, whole brain, brain gray matter, and brain white matter. In addition, density, specific-heat, and water-content measurements were also obtained on these organs. In-vivo conductivity data have recently been obtained for canine liver with and without blood flow. These data indicate that the in-vivo value without blood flow is approximately the same as the in-vitro value after the organ had been removed and refrigerated for 24 hr. Blood flow, if not considered, resulted in apparent conductivities which were 15 to 25 percent higher than that of the tissue.
136 citations
TL;DR: This paper presents several fault-testing models for the k-out-of-n type k/n system, composed of n components that either work or fail, making the series n/n and parallel 1/n systems special cases.
Abstract: This paper presents several fault-testing models. Our system is composed of n components that either work or fail. The systems treated are the k-out-of-n type k/n. This system works if and only if k or more of its components work, making the series n/n and parallel 1/n systems special cases. Components can be individually tested and tests give perfect information. Each test has a time to complete it and testing procedures are judged by the expected cumulative testing time they require. In the first model, the components are assumed to function or fail independently of each other. A feasible test procedure must determine as if the system is working or has failed. This is solved for the series and parallel systems and, under a possibly restrictive hypothesis, for the general k/n system. In another model, the components are assumed to be nominally independent conditioned on the system being failed. Here a feasible test procedure must locate all failed components. This problem is solved for the general k/n system.
72 citations
TL;DR: In this article, a means of resolving incident and reflected wave heights for a partial standing wave through the use of two fixed wave sensors is demonstrated, in which the waves incident to the permeable rubblemound breakwater located in Monterey Harbor, CA, are spectrally resolved into incident, reflected and transmitted wave components.
Abstract: A means of resolving incident and reflected wave heights for a partial standing wave through the use of two fixed wave sensors is demonstrated. Field studies were conducted in which the waves incident to the permeable rubblemound breakwater located in Monterey Harbor, CA, are spectrally resolved into incident, reflected and transmitted wave components. Power-spectra and cross-spectra are calculated for various characteristic sea states. Amplitude and phase are determined for the spectral wave components compromising the partial standing wave phenomena and reflection and transmission coefficients determined. The reflection coefficients vary between 0.3 and 0.7 and the transmission coefficients between 0.1 and 0.2. The transmission and reflection coefficients are shown to be dependent on the frequency and amplitude of the incident waves and the tidal stage.
55 citations
TL;DR: In this paper, the authors deal with the interaction of a train of regular surface waves with a large submerged oil storage tank resting on the ocean floor, in water of finite depth.
Abstract: In the design of submerged oil storage vessels where the structure generally has limited net negative buoyancy, the wave forces are of considerable importance in the design. This paper deals with the interaction of a train of regular surface waves with a large submerged oil storage tank resting on the ocean floor, in water of finite depth. Linear wave theory is used to describe the incident wave and viscous effects are neglected on the basis that the size of the submerged object is large compared to the height of the incident wave. The problem is formulated in the form of a potential flow problem and to solve this problem, point wave sources are distributed over the immersed surface. The strengths of these sources are then adjusted to satisfy the no-flow condition at the surface of the object. Results from a computer program based on these theoretical concepts are compared with experimental results from wave channel testing.
53 citations
TL;DR: In this article, the authors developed a method of deriving gravity models from extremal principles, which yields the most popular gravity flow model characterized by an extremal principle, and elucidated as an information-theoretic one of choosing the distribution of interzonal transfers which gives least information (in the technical sense) for discrimination against a distribution reflecting the facility of travel between zones.
Abstract: : The paper develops a method of deriving gravity models from extremal principles. The prototype result yields the most popular gravity flow model characterized by an extremal principle. This principle is also for the first time elucidated as an information-theoretic one of choosing the distribution of interzonal transfers which gives least information (in the technical sense) for discrimination against a distribution reflecting the facility (reciprocal of the difficulty) of travel between zones. (Author)
40 citations
40 citations
TL;DR: In this article, the elastic-plastic analysis of unidirectional-filament reinforced composites subjected to longitudinal loading is performed based on special generalized plane strain conditions, finite element techniques and Prandtl-Reuss incremental plasticity relations.
Abstract: This paper considers the elastic-plastic analysis of unidirectional-filament reinforced composites subjected to longitudinal loading. The method of anal ysis is based on special generalized plane strain conditions, finite element techniques and Prandtl-Reuss incremental plasticity relations. The results for a boron/ aluminum composite and a boron/epoxy composite were compared to show the relation between composite behavior and the material properties of the matrix.
38 citations
TL;DR: Results of the comparison indicate that the method based on triangular factorization of the covariance matrix generally requires less memory space and computer time than the other two methods.
Abstract: Three methods for generating outcomes on multivariate normal random vectors with a specified variance-covariance matrix are presented. A comparison is made to determine which method requires the least computer execution time and memory space when utilizing the IBM 360/67. All methods use as a basis a standard Gaussian random number generator. Results of the comparison indicate that the method based on triangular factorization of the covariance matrix generally requires less memory space and computer time than the other two methods.
37 citations
29 Jan 1972
TL;DR: In this article, the wave-induced sand transport alongshore is investigated by an energy principle approach by comparing theory and measurements of the distribution of littoral transport along a line perpendicular to the beach.
Abstract: The wave-induced sand transport alongshore is investigated by an energy principle approach. Although the energy approach has been used before, this is the first application to comparing theory and measurements of the distribution of littoral transport along a line perpendicular to the beach. Bed load transport equations are formulated for outside and inside the surf zone. Sand transport data were collected in the field using bed load traps. Wave, tide, wind, and current information was collected simultaneously in order to verify the derived predictive equations for longshore current and sediment transport. Quite reasonable predictions are obtained for the relative distribution of bed load transport, both inside and outside the surf zone.
34 citations
TL;DR: In this paper, a numerical technique with simultaneous time integration of a meshed grid system is proposed, in which the fine-mesh region is able to move within the coarse-means grid.
Abstract: A numerical technique with simultaneous time integration of a meshed grid system is proposed, in which the fine-mesh region is able to move within the coarse-mesh grid. The interface boundary conditions employed are shown analytically to be the only stable specification of those tested for a simple linear case. Numerical experiments with linear and nonlinear systems in one dimension are used to demonstrate the method by which the fine-mesh region is kept centered over a specified disturbance. Forecast results using the meshed system are compared with those from uniform coarse and fine grids. One important criterion is that the solution within the fine-mesh region of the meshed grid must have nearly the same accuracy as in a system which uses a fine mesh everywhere. The technique is applied to a two-dimensional (y, p), ten-level, primitive equation model. Behavior of the meshed model is examined in experiments in which a small-scale heat source is imbedded within an undisturbed zonal flow pattern....
TL;DR: In this article, a digital computer program for the geometrically nonlinear static and dynamic response of arbitrarily loaded shells of revolution is described, which is based upon Sanders' nonlinear thin shell theory for the conditions of small strains and moderately small rotations.
05 Dec 1972
TL;DR: A rationale for implementing software reliability programs is presented; software reliability is defined; some of the problems of performing software reliability analysis are described; and a methodology for reliability prediction and quality control is presented.
Abstract: The increase in importance of software in command and control and other complex systems has not been accompanied by commensurate progress in the development of analytical techniques for the measurement of software quality and the prediction of software reliability. This paper presents a rationale for implementing software reliability programs; defines software reliability; and describes some of the problems of performing software reliability analysis. A software reliability program is outlined and a methodology for reliability prediction and quality control is presented. The results of initial efforts to develop a software reliability methodology at the Naval Electronics Laboratory Center are reported.
TL;DR: In this article, the second order ferroelectric transition in triglycine sulfate and Rochelle salt was investigated and it was demonstrated that crystal quality can affect the heat capacity measured in the immediate vicinity of the transition.
Abstract: Calorimetric studies employing small temperature intervals were made of the second order ferroelectric transitions in triglycine sulfate and Rochelle salt. No evidence of a heat capacity divergence was observed in Rochelle salt. No strong heat capacity divergence was observed in triglycine sulfate, an observation which may be attributed to the quality of the crystals available for study. In triglycine sulfate it was demonstrated that crystal quality can affect the heat capacity measured in the immediate vicinity of the transition.
TL;DR: In this paper, a method is presented for evaluating two-dimensional crack behavior in rocket motor geometries for pressure loadings in which the pressure is applied directly to the crack surfaces.
Abstract: A method is presented for evaluating two-dimensional crack behavior in rocket motor geometries for pressure loadings in which the pressure is applied directly to the crack surfaces. The experimental requirements associated with pressurizing the crack necessitated the application of pressure over the two-dimensional plane surface of the specimen. Analytical solutions are developed which include the side pressure and relate the stress intensity factors to the classical unpressurized situation. Stress intensity factors for the complex cracked rocket motor geometries were evaluated using finite element computer techniques based on strain energy methods. Comparison between analytical predictions using elastic fracture mechanics and experimental observations of a brittle epoxy was quite good for the three different geometries tested. The work has application in fracture analysis of solid propellant rocket grains and in pressure vessels containing partial-thickness cracks which emanate from the inside.
TL;DR: In this article, the decay of surface capillary-gravity waves passing through a zone of turbulent water suggests a dissipative decay mechanism that is proportional to the square of the wave amplitude.
Abstract: The decay of surface capillary-gravity waves passing through a zone of turbulent water suggests a dissipative decay mechanism that is proportional to the square of the wave amplitude.
01 Apr 1972
Abstract: A digital computer program known as SATANS (static and transient analysis, nonlinear, shells) for the geometrically nonlinear static and dynamic response of arbitrarily loaded shells of revolution is presented. Instructions for the preparation of the input data cards and other information necessary for the operation of the program are described in detail and two sample problems are included. The governing partial differential equations are based upon Sanders' nonlinear thin shell theory for the conditions of small strains and moderately small rotations. The governing equations are reduced to uncoupled sets of four linear, second order, partial differential equations in the meridional and time coordinates by expanding the dependent variables in a Fourier sine or cosine series in the circumferential coordinate and treating the nonlinear modal coupling terms as pseudo loads. The derivatives with respect to the meridional coordinate are approximated by central finite differences, and the displacement accelerations are approximated by the implicit Houbolt backward difference scheme with a constant time interval. The boundaries of the shell may be closed, free, fixed, or elastically restrained. The program is coded in the FORTRAN 4 language and is dimensioned to allow a maximum of 10 arbitrary Fourier harmonics and a maximum product of the total number of meridional stations and the total number of Fourier harmonics of 200. The program requires 155,000 bytes of core storage.
TL;DR: In this paper, it was shown that a widely quoted necessary condition on the Lagrange multiplier associated with a first-order state variable inequality constraint is not equivalent to Gamkrelidze's multiplier condition.
Abstract: This correspondence points out that a widely quoted necessary condition on the Lagrange multiplier associated with a first-order state variable inequality constraint is not equivalent to Gamkrelidze's multiplier condition. An example is given of a problem for which the latter stronger condition is required to determine optimal trajectories.
TL;DR: An experimental investigation of ammonium perchlorate (AP)-binder (PBAA) sandwich combustion was made in standard and high acceleration environments as mentioned in this paper, where an optically equipped combustion bomb mounted on a centrifuge and a standard combustion bomb were used in the investigation.
Abstract: An experimental investigation of ammonium perchlorate (AP)-binder (PBAA) sandwich combustion was made in standard and high acceleration environments. An optically equipped combustion bomb mounted on a centrifuge and a standard combustion bomb were used in the investigation. High speed color motion pictures and schlieren were taken during the combustion process. Principal results were: binder thickness as little effect upon regression rate; sandwich combustion is acceleration sensitive and results in part from binder melt/AP deflagration interaction; below the low pressure deflagration limit (P dt ) of ammonium perchlorate the sandwich combustion process is laminar with combustion continuing for large distances above the binder/AP interface; above the P dt of AP the sandwich combustion process appears to be turbulent and consists of two distinct flame regions.
TL;DR: In this article, a tensile stress-strain curve is defined as the point in the tensile tensor curve beyond which plastic strain occurs, and the relationship of these stress components is known as a criterion of yielding.
Abstract: Elastic limit denotes the point in a tensile stress-strain curve, beyond which plastic strain occurs. Under combined loadings, the combinations of different stress components giving the start of plastic strain define initial yielding. After the specimen is loaded beyond the initial yielding, and then unloaded, the different combinations of the stress components to give further plastic strain define a SUbsequent yielding. These combinations of stress components plotted in a space with stress components as coordinates give a surface in this space known as yield or loading surface. The relation of these stress components is known as a criterion of yielding. An ordinary piece of poly crystalline metal is composed of many individual crystals. Single crystal tests [1-4 ) show that crystals slide under stress along certain crystallographic directions on certain crystal planes. This slip depends on the shear stress in this direction on this plane and is independent of the normal pressure on this sliding plane. This sliding causes plastic strain. The orientations of crystals in the metal are random. The polycrystal initially has no particular preferred direction nor particularly preferred plane. This polycrystal is initially isotropic and, hence, the initial yielding depends only on the magnitudes of the three principal stresses and not on their directions. This ihitial yield may be expressed in the form
TL;DR: A complete solution is derived to the Isbell and Marlow fire programming problem and this solution process suggests a solution procedure applicable to a wider class of tactical allocation problems, terminal control attrition differential games.
Abstract: A complete solution is derived to the Isbell and Marlow fire programming problem. The original work of Isbell and Marlow has been extended by determining the regions of the initial state space from which optimal paths lead to each of the terminal states of combat. The solution process has involved determining the domain of controllability for each of the terminal states of combat and the determination of dispersal surfaces. This solution process suggests a solution procedure applicable to a wider class of tactical allocation problems, terminal control attrition differential games. The structure of optimal target engagement policies in “fights to the finish” is discussed.
TL;DR: It is shown that the sequential decoding of rate one-half convolutional codes leads to a special type of infinite Markov chain in which only one transition of one step toward the origin state is permitted but any number of transitions away from theorigin state are permitted.
10 Apr 1972
TL;DR: This article used multidimensional scaling to identify dimensions of political appeal and then used the results of the multi-dimensional scaling were then used in predicting expressions of preference for political personalities and found that most voters do not base their votes on rational or ideological notions, while Key's ( 1966) work appears to indicate the opposite.
Abstract: This paper describes results of a study in which multidimensional scaling was used to identify dimensions of political appeal. The results of the multidimensional scaling were then used in predicting expressions of preference for political personalities. Political practitioners and theoreticians alike have long been interested in determining what elements are involved in the popularity of a political personality. The most sophisticated empirical work on this topic has been done by the Survey Research Center at the University of Michigan (Campbell, Converse, Miller, & Stokes, 1960) and by the late V. 0. Key ( 1966; Converse, Miller, Rusk, & Wolfe, 1969). The Survey Research Center studies seem to indicate that most voters do not base their votes on rational or ideological notions, while Key's ( 1966) work appears to indicate the opposite. Our purpose was to assess multidimensional scaling as a method for further exploring the question of how voters make their preferences. The technique used was Kruskal's method for nonmetric multidimensional scaling ( 1964). METHOD
01 May 1972