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Prototype membrane materials for possible use as separators of ballast water and oil in cargo tanks of oilers and tanker ships (in a membrane oil pollution prevention system, MOPPS) have been evaluated for their resistance to microbial deterioration. Fabric reinforced elastomer composites of two types were tested: neoprene/nylon fabric/nitrile and Hydrin/nylon fabric/Hydrin. Samples with cold and hot-formed seams were also tested. Following exposure in systems inoculated with microorganisms commonly associated with fuels for periods up to one year, membrane specimens were inspected visually and by light and electron microscopy and also subjected to standard physical tests. The changes observed appeared to be due to oil and water exposure rather than to microbial deterioration. Although the neoprene/nylon/nitrile membrane appeared a promising choice for further performance evaluations, it is essential that pinholes and open cut edges at seams be minimized if extensive diffusion of water and oil into the fabric and the accompanying weakening of the fabric-elastomer bond are to be avoided. Numerous microscopic cracks were noted in the exposed Hydrin surfaces indicating that the formulation of this rubber should be reevaluated if it is to be retained as a possible backup membrane candidate. (Author)

An active holographic and a conventional imaging techniques were compared, with the images for both cases taken simultaneously at a range of 1 km. A 1-joule Q-switched ruby laser with a 1-m coherence length was used as the light source. To obtain both a conventional image and a holographic interference pattern simultaneously through one aperture, a beamsplitter and two cameras were mounted at the focus of a 36-cm-diameter telescope. Tests were conducted for several weeks, involving 257 exposures. At best, holographic imaging showed an improvement in resolution over conventional imaging by a factor of 2 but with a decrease in signal-to-noise ratio. (Author)

The results of calculations of the ionization equilibrium and radiative energy loss rates for C, N, and O ions in low-density plasmas are presented for electron temperatures in the range 10,000 to 10,000,000 K (about 1 to 1000 eV). The ionization structure is determined using the steady-state corona model, in which electron impact ionization from the ground states is balanced by direct radiative and dielectronic recombination. Using an improved theory, detailed calculations are carried out for the dielectronic recombination rates in which account is taken of all radiative and autoionization processes involving a single-electron electric-dipole transition of the recombining ion. The radiative energy loss processes considered are electron-impact excitation of resonance line emission, direct radiative recombination, dielectronic recombination, and electron-ion bremsstrahlung. For all three elements, resonance line emission resulting from 2s - 2p transitions produces a broad maximum in the energy loss rate near 100,000 K (about 10 eV). (Author)

The time development of air sparks initiated on aerosols near the focal region (f = 3m) of a 1 kJ CO2 laser beam has been studied. The spark at each aerosol produced a shock wave that expanded spherically at approximately 200000 cm/sec during the 1.5 microsec. tail of the laser pulse. In time these spherical waves coalesced forming a turbulent cylindrical column from which a cylindrical blast wave separated. The turbulent cylindrical region was nearly stationary ( 100 microsec. time scale) and was able to conduct electrical streamers at greatly enhanced velocities, approximately 5000Km/sec at times as long as one millisecond after the laser pulse. (Author)

The laser fusion program concentrated its efforts in two areas: laser-plasma interaction and Nd-glass laser systems. Major experiments included a layered target, light scatter, fast ion studies with a newly-developed ion mass spectrometer, compressed probe beam including work on its third harmonic, compressed square pulses using a cesium cell, measurement of gain of glass in realistic pump geometry optimization of glasses, system quality and reliability improvements, automatic laser alignment, lead oxide vidicons. This report is divided into two sections, text and selected reprints, to encompass the range of NRL's research effort.

Let p and q be probability densities. The directed divergences of p and q are given by the integral p(x) log (p(x)/q(x))dx and by the same expression with p and q interchanged; the divergence is the sum of the directed divergences. These quantities have applications in information theory and to the problem of assigning prior probabilities subject to constraints. In this report, it is shown that the directed divergences and their positive linear combinations, including the divergence, are characterized by axioms of positivity, additivity, and finiteness; in the course of the proof, the latter two are shown to imply yet another axiom; imvariance. These axioms are fundamental in work on prior probabilities. It has been claimed that they characterize only constant multiples of the single directed divergence; that claim is here refuted.

Angular distributions of scattered laser light from Nd-laser-produced plasmas at irradiances between 10 to the 15-th power and 10 to the 16th power W/sq cm were measured. Total reflectivities in the range of 20% to 50% are found. The total reflectivity remains approximately constant as the target is rotated from normal incidence up to 50-60 deg implying the existence of a steep density gradient near the critical density and/or absorption of laser light in the underdense region of the plasma.

The Transition Analysis Program System (TAPS) has been implemented on the Advanced Scientific Computer (ASC) at NRL. No changes in the original program have been made to take advantage of the pipeline architecture of the ASC, but some vectorization of the code is performed by the computer. Comparisons of computational results, run times, and costs of flow problems solved with TAPS on the ASC and other computational facilities are presented and their significance discussed. (Author)

The fracture surfaces of fatigue specimens of Type 304 stainless steel previously tested at elevated temperatures in air were examined by scanning electron microscopy (SEM) to characterize the failure processes and establish correlations with previous studies performed at NRL of fatigue crack propagation in Type 316 stainless steel. The SEM observations showed significantly different types of fatigue behavior which could be explained in terms of differences in material processing history and test conditions. Solution-annealed (SA) material tested at 427 C (800 F) exhibited a transgranular failure mode with fatigue striations indicative of a ductile failure process. Solution-annealed material tested at 593 C (1100 F) showed a change in failure mode to partially intergranular failure and an increase in the crack growth rate relative to tests at 427 C. Imposition of a hold time up to 1 min further increased the proportion of the fracture surface characterized by intergranular failure, and the crack growth rate also increased. The material that had been aged at 593 C and tested at 427 C and at 593 C showed a return to transgranular failure. The crack growth rate in the aged material tested at 427 C was comparable to that of the SA material tested at the same temperature, while the growth rate of the aged material at 593 C was somewhat higher than at 427 C. Observations were consistent with a model in which the grain boundaries were embrittled by diffusion of oxygen ahead of the crack tip, resulting in intergranular failure and an increased crack growth rate.

Results are reported for a long-range deep-ocean experiment in which a 15-Hz CW source was towed transverse to the line of propagation to a single receiver. Reciprocity between transmitter and receiver roles is used to interpret the aperture formed by the moving source as a large receiving aperture. For the shallow source and bottom-suspended SOFAR-axial receiver employed, we observed the largest physical broadside apertures yet reported over which the received signal was coherent. The maximum observed coherent interval corresponds to a broadside aperture of 14 km at 1600 km range. The measured array gain for this aperture was 1.2 dB less than the maximum possible. (Author)

The line-source bootlace lens, produces optimum focusing characteristics when it is constrained to exhibit front-to-back as well as right-left symmetry. It is shown that the symmetric bootlace lens is a one-parameter family when the radiating array is specified to be lambda/2 spaced with + or - 90-degree coverage. Design equations for the lens are derived, and overall focusing performance and design data are plotted. A computer program of the design equations is presented.

The Surveillance Radar Systems Evaluation Model (SURSEM) is a user-oriented computer model designed to generate radar single-scan and cumulative probability of detection values as a function of target range and orientation within a specified environment. A model overview, instructions for the potential SURSEM user, and a detailed description of each SURSEM subroutine have been developed as well as a FORTRAN program listing and a description of MTIMOD, a moving target indicator signal-processing subprogram to be integrated into SURSEM. (Author)

This report derives the thermonuclear yield from a cylindrical plasma with beta 1 (specifically, a reversed-field theta-pinch configuration) being compressed by an imploding liner. Since magnetic field is mixed with plasma, the average plasma density, and hence the fusion output are reduced in comparison with the beta = 1 systems considered previously. The trajectory of the liner is also modified due to the increased gamma (ratio of specific heats) of the plasma-field mixture. For the same peak field and system size, the value of Q (ratio of fusion output to system energy) is reduced to a fraction s of its value in the beta = 1 case, where s depends upon the initial pressure distribution in the plasma, and upon the compression ratio; over the likely range of parameters, 0.1 s 0.3. The significance of this result for the design of LINUS fusion systems is discussed. (Author)

A simple and convenient method is described for estimating the relative esterification rates of unknown fatty acids, HCl catalyzed in methanol. All that is essential is a reasonably quantiative chromatographic procedure for resolving a set of acids and their methyl esters. Satisfactory estimates are obtained from acids with relative rates greater than 0.001 where the relative rate of a normal acid is 1.00. With a slight modification, relative rates of slower reacting acids can be adequately determined. (Author)

Designers often cannot prevent cracking in machinery components or structural members. Uncontrollable factors such as undetected manufacturing defects and unforeseen service conditions can initiate cracking that affects safety, reliability, and maintenance. One way designers can compensate for these is in selection of alloys for optimum crack-growth resistance. Enhancement of crack-growth resistance is now an active area of material research. This report summarizes recent information that can help design engineers with problems involving stress-corrosion cracking and fatigue crack growth. (Author)

Dielectric slab center loaded ridged waveguide has been analyzed to obtain TE sub 10 propagation characteristics for the losses case. The analysis was performed by solving for the lowest order resonance of the transverse wave component, using an equivalent transmission line circuit which models the height change at the ridge as an effective shunt susceptance. Calculated and measured data are compared; they show good agreement. The analysis should prove useful in designing transformers to match empty ridged waveguide to slab loaded rectangular waveguide components such as toroidal phase shifters. (Author)

A quantitative thin-layer chromatography (TLC) method with a relative standard deviation of four percent is described for the analysis of commonly used amine antioxidants in high-temperature jet engine lubricants. The method is convenient in that after development of the plates, the components develop characteristic visible colors suitable for analysis. (Author)

Methods have been developed at NRL to sample the NACL exhaust. These methods include particulate, fluoride, and on-line mass spectrometric analysis. The only toxic gases detected were HF and DF. Their concentration in the final exhaust varied between 500 and 10,000 ppm. The particulate matter consisted of iron fluoride and iron oxide. Ten to fifteen percent of the fluorides and 85% of the particulate matter are removed by the pumps. (Author)

High-power microwave radiation of frequency 11 GHz and 36 HGz is observed when a 300 kV positive pulse is applied to an aluminized mylar anode of a reflex triode. The frequency of radiation varies as (square root of V)/(d to the n-th power), where V is the anode voltage, d the anode-cathode spacing and 0 n 1. The basic features of the radiation are explained by a theoretical model based on the energy dependence of the electron oscillation frequency.

A multiport RS232-NTDS Multiplexor will be discussed. This microprocessor driven hardware device has the capability of multiplexing up to 48 RS232 ports into a single parallel NTDS channel obeying intercomputer protocol. Each RS232 port has software programmable functions similar to AN/UYK-20 RS232 functions. The device is modular so that RS232 ports may be added incrementally as needed. The device is flexible: a very general priority interrupt structure is provided by a combination hardware logic and microprocessor firmware. As a result of this flexibility and modularity, the device can easily accommodate special purpose peripheral devices. The motivation for construction of the device will be discussed along with possible applications. Salient design features affecting flexibility, modularity and throughput will be discussed. This is a final report on this phase of the problem. (Author)

Accumulating information regarding the equatorial F-region ionosphere has proven it to be a particularly important domain for the communications and ionospheric sciences as well as investigation of fundamental plasma processes that have counterparts in atmospheric releases and controlled laboratory experiments. This wide range of interest has in recent years brought considerable intensity into equatorial investigations with major technical, scientific, and engineering advances contributing to our current understanding and future plans for adaptive communication system design and ionospheric modification and control. Rapid advances require occasional synthesis in order to draw proper perspectives and establish an improved definition of near-term and longer range plans. This document bears that objective, particularly as it relates to radar, rocket, and satellite studies of the turbulent ionospheric plasma state, the theoretical and computational descriptions, and chemical releases for controlled ionospheric modifications. Emphasis is placed on important relationships involving spread F, naturally-occurring ionospheric bite-outs, and artificial ionospheric holes. Current understanding is reviewed, deficiencies identified, and future programs involving the Naval Research Laboratory are discussed.

A computer code listing, definition of terms, and CSN step commentary are presented as a supplement to the paper 'Beam-Plasma Heating Model', by D. A. Hammer, A. W. Ali and myself. Together, these papers should allow application of our heating code to a wide and varied range of beam and plasma parameters and resistivity models. (Author)

A means of sending only the best raw detections from radars to update a track is considered. A specific error-filtering concept and method of implementation are introduced. The method depends on comparing the last three raw detections with the current raw detection under test to determine if it will significantly aid the track. In addition the method does not require any additional information be sent over the channel for its implementation. Finally, track updating using range and range rate from at least three noncolocated radars is considered. This method would require little information to be transmitted on the channel, but it is useful only when certain criteria are met. Combinations of both methods may provide the best solution. (Author)

Design, construction, and performance of a dual-acoustic-channel interferometer, capable of placing nulls spaced every 150 kHz from 329.15 to 335 MHz, are described. The prototype device constructed exhibited a minimum null depth for 40 consecutive nulls of 33 dB, with more than half the nulls being 45 dB or more. Midband insertion loss was 27 dB. Second-order effects, such as spurious signals, required some design tradeoffs. Slight modifications of the prototype should enable 50 dB nulls to be achieved with an insertion loss of 20 dB. (Author)

This report describes the conceptual design of a fusion reactor based on the dynamic compression of a magnetically-confined DT plasma by an imploding liquid lead-lithium liner. Stable implosion-expansion cycles are achieved by rotating the liner, and imploding it by a means of a rigid mechanism driven by high pressure helium (the 'captive liner' principle). At peak compression the magnetic field is 0.5 MG and the liner is 1 m thick, which is enough to absorb the fusion neutrons. The energy of the trapped alpha-particles is directly recovered in the expansion and compensates for the resistive and mechanical losses in the liner, making the mechanical cycle self-sustaining. The reactor works rather like an internal combustion engine, except that there is no shaft output: all the nuclear energy appears in the liner as heat. The initial plasma is created by means of a pulsed rotating relativistic electron beam injected from one end. The beam sets up both the plasma and the confining magnetic field, and no external magnet coils are required. The reactor is repetitively cycled at 1.67 Hz for a gross electrical power output of 1000 MW., Errata sheet inserted.

A simple model is developed to describe the compression of a plasma to high density and fusion temperature by a thick, compressible imploding liner. In contrast to previous thin liner calculations, the dwell time around peak compression is now less than the transit time of a sound wave through the liner, and thus only the inner part of the liner contributes to the inertial confinement of the plasma. The model first derives the size of the active part of the liner, and goes on to determine the final conditions (pressure, radius, etc.,) achieved by the compressible liner in terms of the same quantities derived from the incompressible model used previously. The effect of resistive diffusion of magnetic field into the inside surface of the liner is treated as a perturbation. Finally, the results of the model are used to determine the working point of a LINUS reactor. (Author)

The NRL applications software package in the 'interim' system is a multi-tasking code embodying a single task overlay and is resident on a Data General NOVA 800 minicomputer. The operating tasks are a data display task, QLOOK; a data base write task, UPDTDB; a communications driver task, NLINK2; and a message processing task, PROCT. All tasks other than QLOOK are continuously core resident during operation. QLOOK, because of its size, must be overlayed with only a small root program continuously core resident. QLOOK is the main system task in the sense that it prepared the system to receive the other tasks and then activates them. Once a task is activated, access to the CPU in determined by the RDOS (real-time disk operating system) TASK SCHEDULER according to priority. Since the data display task is of lesser urgency than the real-time data base update, QLOOK lowers its priority after activating the other tasks. The RDOS protocol for task ACTIVATE, ABORT, READY and SUSPEND is designed to make most efficient use of the CPU. Providing adequate access to the CPU for each task is largely a design factor for the code designer.

The quality of PFOMA barrier films, e.g., thickness, smoothness, surface texture, and resistance to lubricants, is shown to depend on the formulation variables of the PFOMA-solvent solutions from which they are cast. Thus, barrier film properties can be optimized by the choice of solvent composition and concentration. Scanning electron microscopy, optical microscopy, visual observation of drying films, and contact angle measurements all showed the relation of film properties to the solution variables. This was further established by calculating solubility parameters for the compositions studied, which showed that thermodynamically good solutions formed the best barrier films. Polymer phase partitioning probably occurred in a ternary solvent mixture resulting in unusually poor films. The relation of solution thermodynamics to the film properties was the basis for selection of an optimum solvent composition. From these techniques, an optimum concentration for casting was found to be one yielding a film thickness of about 0.5 micrometers. (Author)

This annual report of the NRL Inertial Confinement Fusion Theory Program covers research performed in each of the following five current program areas: (A) Transport of Charged Partcle Beams; (B) Laser and Particle Beam Absorption; (C) Fluid Dynamics and Ablative Acceleration; (D) Development of Computational Techniques; and (E) Rayleigh-Taylor Stabilization Techniques.

A review of the excitation and deexcitation processes relevant to the disturbed and the quiescent upper atmosphere is presented along with the current reaction rate coefficients.

The solution of linear integral equations of the form f1(x)g(x)+f2(x)g(x)+f3(x) = integral from a(x) to b(x) of k(x,y)g(p(x,y))dy is considered. The equations is reduced to a set of linear algebraic equations in the values of g(x) on a finite mesh. The method entails formal orthogonal polynominal quadrature of the integral and subsequent formal cubic spline interpolation for the values of g at the mesh points. Discontinuities in the derivatives of g are accommodated. (Author)

Six design categories were applied to design a three-bar structure connecting two rigid masses. The structure was taken as redundant, made of an elasto-plastic material, and required to resist dynamic loads applied independently from two directions. Weight and deformations of the structures are compared. Two of the categories allow significant reduction in the weight of the structure without producing excessive deformation.

The Naval Research Laboratory is carrying out a study to collect and evaluate mathematical and computer-based routines for performing the correlation function in Naval ocean surveillance. The correlation function, generally embedded within computerized correlator-trackers, concentrates on determining whether certain elements of the surveillance data base--contact reports or tracks--relate to the same platform. The goal of correlation activities is to partition the data base, so that each set which is a member of the partition is the collection of all data base elements which relate to a specific platform. The major product of this project is a handbook of correlation schemes, in which such schemes are listed, compared, and evaluated. Specific operations research questions within this project include the determination of measures of effectiveness for comparing correlation routines and the evaluation of routines which have been run on simulated data.

A free electron laser using an intense relativistic electron beam in a rippled magnetic field has been operated in the stimulated Raman scattering regime to yield megawatt-level radiation at submillimeter wavelengths; line-narrowing to Delta lambda/lambda approximately 2% is reported. (Author)

This report describes the characteristics of a high power Nd/glass laser presently in operation at the Naval Research Laboratory. The laser will produce 100 J of 1.06 micrometer radiation in a 40 nsec pulse, or in two pulses each of which is 40 nsec wide and separated by 300 nsec to 5 microsec. The divergence of the laser beam is approximately 0.0003 radian so that power densities in excess of 10 to the 13th power watts/sq cm can be achieved. This Nd/glass laser, is not 'state of the art' rather it is conservatively rated to provide reliable operation over long periods, with minimum maintenance. (Author), See also Rept. no. BRL-MR-3315 dated Aug 76, AD-A029 408.

Particulate aerosol size spectra obtained during the CEWCOM-78 exercise (8-22 May 1978) at San Nicolas Island, California, are presented for the particle size range 0.745 micrometers diameter as measured with a PMS Axially Scattering Spectrometer Probe. In addition, an informal account of the daily meteorological and visibility conditions as observed visually from several vantage points on the island is given to help in the interpretation of the aerosol and optical data collected during the measurement session. These observations point out: (1) the need for slant path optical transmission measurements due to the generally strong, vertical gradient in visibility in the lowest 300m or so above sea level, (2) the general susceptibility of Sites A and D to surf-generated aerosols and the additional susceptibility to dust for winds above 10m/sec, (3) the suitability of the upper two levels of the NRL tower for representative aerosol measurements except possibly during near calm wind conditions, (4) the suitability of SNI as a site for obtaining optical transmission measurements in maritime clouds, and (5) the existence of a newly observed phenomenon in which the downward vortex of air behind large, breaking or cresting waves in high wind situations prevents much of the crest-generated spray from becoming airborne. This mechanism may help explain the recently reported cases where the particle concentrations are lower and the visibilities are better in high wind situations than is to be expected from aerosol models where particle number densities increase indefinitely with wind speed. (Author)

This is the final report of a series of three on measurements of 1.3-GHz (L-band) electromagnetic wave, forward reflection coefficients of the ocean. The L-band line-of-sight path was chosen between a transmitter in an aircraft flying at constant altitude towards receiving horns mounted on the stabilized platform of a destroyer. Six days of data were obtained by flights off the Atlantic Coast in 1974. Wave heights were measured by an airborne laser profilometer. The measured L-band forward reflection coefficients followed Ament's theoretical curve as a function of apparent surface roughness (sigma sub w sin psi)/lambda for the small roughnesses encountered ( or = 0.1). A remote sensing method for significant wave height emerges from recasting Ament's theoretical expression into a series of curves vs grazing angle (psi), with wave height (sigma sub w) as a parameter. Plotting the measured reflection coefficients on this graph then yields significant wave height (4 sigma sub w) directly. The average spread in the values of sigma sub w predicted by this method is + 0.12 ft for values of sigma sub w from 0.4 to 0.9 ft. An FM-sweep system is proposed which should improve this accuracy. (Author)

Progress accomplished during the Second Quarter of FY79 in the Sonar Transducer Reliability Improvement Program is reported. Each of the nine program tasks are discussed in some detail. The most significant aspects are failure modes in the new TR-215 ( ) transducer design and the testing techniques used to discover them, the problem of not being able to measure very low background noise, the quantification of corona levels on ceramic, and the development of the sleeve spring pressure release mechanism. (Author)

A 2-meter-long cell has been devised in which aerosol extinction and scattering coefficients can be measured simultaneously. Extinction is obtained by measuring the change in the intensity of a HeNe laser beam which is stepped through the cell for a total path length of 20 meters. A reciprocal nephelometer consisting of a sensor with a precise Lambertian response is mounted on the side of the cell to give a direct measure of the scattering coefficient. Filling the cell with ambient aerosol that has been concentrated centrifugally increases the effective path length of the beam in the cell to 300 meters. The cell was taken on the 1977 EOMET cruise of the USNS Hayes in order to determine its capabilities when exposed to the rigors of a ship's environment. The variance of data collected during the cruise was analyzed. The mean resolution limit of the transmittance measurements made during the cruise was + or - 0.16%. This limit was primarily influenced by mechanical instabilities in the nephelometer operated precisely. Vibrations from the ship's machinery was damped out successfully. An improved cell could increase the resolution by a factor of 10 or more. Absorption coefficients of the aersol particles in the eastern North Atlantic and in the Mediterranean were plotted. This technique has potential in the infrared. (Author)

EDIT is a MACRO program for automatic maintenance of FORTRAN and RATFOR (RATional FORTRAN) programs on the Texas Instruments Advanced Scientific Computer. It has been used extensively to accelerate the creation of complex fluid dynamics programs for execution on the Advanced Scientific Computer (ASC). EDIT allows the user to more efficiently create and modify programs using the TI-supplied Source Management System, SMS. Object libraries and load modules may also be automatically updated. The program files (source, object, and load module) may be tape or disk resident and will always have a user-specified number of versions retained as backup. The EDIT system is described and sample usages are presented. (Author), Supersedes Rept. no. DTNSRDC/CMLD-77/07 dated Mar 77.

A computer system for the automated (numerical integration) of chemical type equations has been developed. The manual describes the use of the system, its input and output, and the incorporation of the generated FORTRAN program in an user program. The developed ARIS system has the following features which are essential for the successful use of such a system: (1) It is complete which means the input to the system is sufficient to generate a complete chemistry program (including error printouts). The generated program is efficient (vectorizable) and simple to incorporate in the user program; (2) The reaction are to be given in a physical form: A + B + ... C + D + ...with reaction energies E,C, ... The programming for initiation, back substitution, rate coefficients, conversion factors and additional source terms is easy. The generated FORTRAN is comprehensible; and (3) The ARIS system provides integration schemes suited for stiff equations with special features for asymptotic behavior. (Author).

This report proposes robust detection theoretic approaches to HF signal reception. Most of these approaches require modifying recent robust detection theory results to the specifics of the HF communication problem. One approach recommended is direct and avoids this modification requirement; however, it demands more original effort. The report contains a survey of recent robust detection theory research and discusses the applicability of the research results to HF additive interference models; it concentrates on the known-signal case to highlight the additive interference problem. (Author)

A fast approximation to the complementary error function has been programmed and tested for use in the peak-shape function for fitting peaks in gamma-ray spectra. The function was compared for speed and accuracy on the NRL ASC 7 computer to the ASC mathematical library version of the complementary error function. The approximation has resulted in a 50% time savings in the computer program HYPERMET which was developed at NRL for automatic analysis of gamma-ray spectra. Source codes for the test progams are given in an Appendix. (Author)

Trans. of Physikalische Zeitschift (Germany, F.R.) v25 p672-675 1924, by Pieter S. /Dubbleday.

X-ray spectra from CH2 laser-generated at 10 to the 16th power W/Sq cm are compared with those obtained using a 2D-mhd code. Good agreement is found over 7 orders of magnitude for X-ray energies comprised between 1 and 300 keV. It is found that the hard X-ray spectrum is compatible with the generation of B-fields in the interaction region. Variation of the numerical results with initial conditions, ion mass, laser energy deposition and grid size is investigated. (Author)

A nonlinear theory for the long-range propagation of sonic booms through the thermosphere has been developed. Arealistic atmosphere is employed, and consideration is given to such factors as nonlinear stretching and decay of the wave, the effects of the caustic, the linear acoustic attenuation, and the increase in Mach number due to the decreasing density at high altitudes, detailed results are presented for the case of the Concorde SST in straight, level and steady flight at 17.5 km and a velocity of Mach 2. We predict maximum ground level pressures of 0.3 Pa with an N-wave period of about 10 seconds. The sound level is a minimum along the flight track with the maximum signal strength occurring about 300 km off the flight track. The strongest received signal travels Initially downward and reflects off the surface of the ocean to thermosphere. The wave turns around at an altitude of 160 km and is returned back to the ground at a horizontal distance of 320 km from the launch point. The acoustic Mach number of the wave never exceeds 0.2. Ninety percent of the wave's energy is attenuated below 100 km with 99% attenuated by the time the wave reaches the turning the turning point. (Author)

A FORTRAN program that computes the optimum sizing parameters of a multi-stage rocket in powered ascent has been developed. The computer program is based upon an optimization procedure, due to Ruppe, which maximized the payload weight to total launch vehicle weight. Based upon a simplified aerodynamic model, the optimization procedure is convenient to use and provides useful approximate values of launch vehicle sizing parameters for launch vehicle of n stages, where n = 0, 1, 2... A numerical example is given to illustrate the utility of the FORTRAN program. (Author)

It has been about 20 years since the first papers in A.I. appeared. In this period, A.I. research has produced many interesting ideas of which list processing is probably the most widely used. Other results of A.I. research include chess programs, etc. Progress has been slower than some people predicted. Therefore, there has developed a body of literature which claims that A.I. effort is misguided. In this paper I will reply to three prominent critics of A.I., Dreyfus, Weizenbaum, nd Lighthill. (Author)

Polyalkylene Glycol (PAG) has been proposed as a sonar-transducer fill fluid with nearly ideal properties, but PAG is far from being a universal fill fluid. Its speed of sound and acoustic impedance are both about 13% lower than those of seawater at 20 C, causing internal reflections (sensitivity loss) and refraction (directivity loss). Low thermal expansion and moderate compressibility make PAG a good choice in a nonpressure-relieved design. The electrical resistivity of PAG is 1000 to 10,000,000 times lower than that of other common fill fluids, partly from high water solubility. Also, some of the large amount of water in PAG at equilibrium will precipitate if the temperature drops and may cause catastrophic failure. Another concern with PAG is low resistivity if exposed to tin salts or perhaps tin, which may cause electrical failure. PAG is in general compatible with fewer acoustic-grade elastomers than caster oil. An advantage of PAG is low viscosity. It is much easier than caster oil to degas; hence air bubbles are less likely. The toxicity of PAG is low, and poisoning by vapors from overheating is easily avoided. PAG is readily available and not costly. If the vendor ceased production, the synthesis and specifications in this report would let additional vendors become qualified. In conclusion, with care in avoiding water exposure and in choosing exposed materials, PAG may find use in several Navy sonar units. (Author)

The gravity-capillary wave interaction has been simplified for the special case where one component of the interacting triad is a short-gravity wave. Wind-speed effects have been included in an ad hoc manner by forcing the dispersion relation to conform to that found in microwave scattering experiments. The results show that the interaction may be envisioned as occuring between the short-gravity wave and a capillary wave whose group speed equals the phase speed of the gravity wave. The interaction dies out as the wave number of the gravity wave decreases, having a k to the 5/2 power dependence in the no-wind case. Comparisons with more accurate numerical evaluations of the interaction are given. (Author)