Showing papers by "United States Department of the Army published in 1981"

Microstrip antenna technology

Abstract: A survey of microstrip antenna elements is presented, with emphasis on theoretical and practical design techniques. Available substrate materials are reviewed along with the relation between dielectric constant tolerance and resonant frequency of microstrip patches. Several theoretical analysis techniques are summarized, including transmission-line and modal-expansion (cavity) techniques as well as numerical methods such as the method of moments and finite-element techniques. Practical procedures are given for both standard rectangular and circular patches, as well as variations on those designs including circularly polarized microstrip patches. The quality, bandwidth, and efficiency factors of typical patch designs are discussed. Microstrip dipole and conformal antennas are summarized. Finally, critical needs for further research and development for this antenna are identified.

Biodegradation of hexahydro-1,3,5-trinitro-1,3,5-triazine.

Abstract: Biodegradation of the explosive hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) occurs under anaerobic conditions, yielding a number of products, including: hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine, hexahydro-1,3-dinitroso-5-nitro-1,3,5-triazine, hexahydro-1,3,5-trinitroso-1,3,5-triazine, hydrazine, 1,1-dimethyl-hydrazine, 1,2-dimethylhydrazine, formaldehyde, and methanol. A scheme for the biodegradation of RDX is proposed which proceeds via successive reduction of the nitro groups to a point where destabilization and fragmentation of the ring occurs. The noncyclic degradation products arise via subsequent reduction and rearrangement reactions of the fragments. The scheme suggests the presence of several additional compounds, not yet identified. Several of the products are mutagenic or carcinogenic or both. Anaerobic treatment of RDX wastewaters, which also contain high nitrate levels, would permit the denitrification to occur, with concurrent degradation of RDX ultimately to a mixture of hydrazines and methanol. The feasibility of using an aerobic mode in the further degradation of these products is discussed.

Microstrip antennas with frequency agility and polarization diversity

Abstract: A technique is investigated for controlling the operating frequency and polarization of microstrip antennas. The control is achieved by placing shorting posts at appropriate locations within the antenna's boundaries. By changing the number and locations of the posts, the operating frequency can be tuned over a 1.5-to-1 range, and the polarization can be changed from horizontal to vertical, right-hand circular, or left-hand circular. All of these changes are obtained without significantly altering the input impedance or radiation patterns of the antenna and without increasing the complexity of the external microwave feed network. The frequency and polarization can be electronically controlled by using microwave switching diodes for the shorting posts. Antennas that have two feeds and operate simultaneously in two orthogonal polarizations have been constructed with the capability to switch between linear and circular polarization. Also, a thin frequency-scanned array has been built with the frequency-agile microstrip elements.

Terminal settling velocity of commonly occurring sand grains

Abstract: Published measurements of terminal settling velocity for commonly occurring sands are used to develop three equations which join into a single segmented curve of dimensionless form. Results are noticeably different from those for spheres of similar diameter, and permit calculation of the settling velocity for usual sand grains without specification of exact grain shape. For quartz in water, the three equations of different settling regimes correspond approximately to: very fine sand; fine to coarse sand; and very coarse sand.

Virtual space teleconference system

Abstract: A teleconference system for N conferees, N being greater than two, includes at least two separate stations. Each station has N conferee positions, confronting a virtual conference space, and corresponding conferee positions at each station have the same relative locations about the virtual conference space. At least one conferee position at each station is adapted to be occupied by a conferee in person. Surrogate conferees, which include a video display, a video camera, and a loudspeaker, occupy each conferee position not adapted to be occupied by a conferee in person. Each video display faces one conferee and displays the image of another conferee at a corresponding position at another station; the loudspeaker reproduces the voice of the other conferee. The video camera forms image signals of the one conferee and couples these signals to the display device of a surrogate conferee at a conferee position corresponding to the position of the one conferee at the other station. The system includes a shared graphic display system. A video display device is positioned at the center of the virtual conference space and has a display screen at about the level of a table top. A target area for each conferee is scanned by an overhead video camera, and the target image signals are combined for display on the screens in the table tops at each station. Images from a video storage device are also combined in the composite signal. The display devices and cameras at each station are so oriented with respect to the virtual conference space that the target images from each station will appear on the screen as oriented the same as the conferee at that station.

Enzymatic hydrolysis of cellulose: Evaluation of cellulase culture filtrates under use conditions

Abstract: Culture filtrates from three mutant strains of Trichoderma reesei grown on lactose and on cellulose were compared under use conditions on four cellulose substrates. Cellulose culture filtrates contained five to six times as much cellulase as lactose culture filtrates. Unconcentrated cellulose culture filtrates produced up to 10% sugar solutions from 15% cellulose in 24 hours. Specific activity in enzyme assays and efficiency in saccharification tests were low for enzymes from all the mutants. Over a wide range the percent saccharification of a substrate in a given time was directly proportional to the logarithm of the ratio of initial concentrations of enzyme and substrate. As a result of this, dilute enzyme is more efficient than concentrated enzyme, but if high sugar concentrations are desired, very large quantities of enzyme are required. Since the slopes of these plots varied, the relative activity of cellulase on different substrates may be affected by enzyme concentration. (Refs. 28).

The role of efferent inhibition in human auditory attention: an examination of the auditory brainstem potentials.

Abstract: This study examined whether the efferent olivocochlear bundle (OCB) functions to attenuate irrelevant auditory stimuli during visual attention. Subjects either counted 8000 Hz, 50 dB SL target tone pips, or target letters flashed rapidly on a visual display. The target stimuli were randomly interspersed among nontarget stimuli to prevent the subjects anticipating their occurrence (Naatanen, 1975). The auditory brainstem potentials were tape recorded for separate analyses of the target and nontarget tone pips. The nontarget tone pips were not significantly affected suggesting they were attenuated in the auditory task (intramodal effect) as well as during the visual task. During focused visual attention, the auditory nerve component to the target tone pips was significantly reduced in amplitude by 37.4% and increased in latency by 90 μsec. Wave V generated partially from the inferior colliculus was also reduced in amplitude by 12.9%; however, this decrement was not statistically significant. The use of 8000...

Korean hemorrhagic fever: propagation of the etiologic agent in a cell line of human origin

Abstract: The etiologic agent of Korean hemorrhagic fever has been propagated in a human cultured cell line derived from a carcinoma of the lung. The cells, described as type II, alveolar epithelial, support replication of the agent and successive passages. Antigen of the Korean hemorrhagic fever agent is readily detected in infected cells by means of direct or indirect fluorescent antibody techniques. Previous attempts to propagate this agent in vitro had been unsuccessful.

Composite floor armor for military tanks and the like

Abstract: A novel composite armor for armored vehicles which attenuates mine blast loading better than monolithic steel armor plate of equal areal density without structural fracture. The disclosed composite armor, particularly used as vehicle floor armor, is designed so as to greatly enhance not only crew survivability, by markedly reduced compressive shock effect, but also vehicular integrity. The novel composite armor in most preferred embodiments comprises layers of high density steel honeycomb, balsa wood, and ballistic-resistant nylon such as KEVLAR, sandwiched in various arrangements between outer layers of steel armor plate.

Magnet position sensing system

Abstract: Magnetic position sensing for an object is disclosed wherein the analogue the distance between an object and a sensor is detected for indicating changes in object position in one, two, or three dimensions. An accurate, and continous output signal indicative of object position and incremental changes in that position are obtained. Additionally, magnetic sensing provides motion sensing of a support structure or velocity and acceleration sensing of an object.

Burn wound infection

Abstract: : Ninety-seven of 763 patients admitted to a burn center during a 3-year period had histologically confirmed bacterial or fungal burn wound invasion. Nine of these 97 patients survived and 88 died. Burn wound infection was the principal cause of death in 57 patients and was diagnosed perimortem in an additional 31 patients but was not judged to be the primary cause of death. Pseudomonas aeruginosa continues as the most frequent offending organism. The variety of mycotic and bacterial organisms identified, however, suggests that the compromise of the host is the critical factor, and not any particular microorganism. A variety of combinations of treatments are described: the selection of treatment depends upon the type and extent of infection.

An outbreak of Mayaro virus disease in Belterra, Brazil. II. Epidemiology.

Abstract: Results of entomological and vertebrate host investigations made during dual outbreaks of Mayaro (MAY) and yellow fever (YF) viruses in Belterra, Para, Brazil in 1978 are reported. Over 9,000 insects representing 26 species were assayed in 396 pools for the presence of arboviruses. Pools of Haemagogus janthinomys Dyar yielded the only isolates of either MAY of YF virus. The minimum field infection rate for nine isolates of MAY virus from Hg. janthinomys was 1:82, and for two isolates of YF virus was 1:368. Analysis of collection data showed Hg. janthinomys to be attracted to man as a blood source and present in all habitats sampled, although most abundant in the forest canopy. Twelve hundred bird sera and 584 mammal sera were tested by hemagglutination-inhibition (HI) tests for antibody to MAY virus. Highest MAY antibody prevalence rates were found among marmosets (Callithrix argentata, 32 positive of 119 tested, 27%). Mayaro virus was also isolated from the blood of a sylvan marmoset captured at the peak of the MAY virus outbreak. Experimental infection of marmosets with MAY virus confirmed that a substantial viremia follows infection with this virus. Marmosets were also found with HI antibody to YF virus (5/119, 4%). The results presented indicate that Hg. janthinomys was the principal vector of both MAY and YF viruses and that marmosets were the main amplifying hosts for MAY virus, and perhaps for YF virus as well.

An outbreak of Mayaro virus disease in Belterra, Brazil. III. Entomological and ecological studies.

Abstract: Results in entomological and vertebrate host investigations made during dual outbreaks of Mayaro (MAY) and yellow fever (YF) viruses in Belterra, Para, Brazil in 1978 are reported. Over 9,000 insects representing 26 species were assayed in 396 pools for the presence of arboviruses. Pools of Haemagogus janthinomys Dyar yielded the only isolates of either MAY or YF virus. The minimum field infection rate for nine isolates of MAY virus from Hg. janthinomys was 1:82, and for two isolates of YF virus was 1:368. Analysis of collection data showed Hg. janthinomys to be attracted to man as a blood source and present in all habitats sampled, although most abundant in the forest canopy. Twelve hundred bird sera and 584 mammal sera were tested by hemagglutination-inhibition (HI) tests for antibody to MAY virus. Highest MAY antibody prevalence rates were found among marmosets (Calithrix argentata, 32 positive of 119 tested, 27%). Mayaro virus was also isolated from the blood of a sylvan marmoset captured at the peak of the MAY virus outbreak. Experimental infection of marmosets with MAY virus confirmed that a substantial viremia follows infection with this virus. Marmosets were also found with HI antibody to YF virus (5/119, 4%). The results presented indicate that Hg. janthinomys was the principal vector of both MAY and YF viruses and that marmosets were the main amplifying hosts for MAY virus, and perhaps for YF virus as well.

Weld quality monitor

Abstract: Weld arc voltage, weld arc current and weld arc travel speed are monitoredn a real-time basis during the welding process. Each monitored quantity or parameter is compared directly with a reference value indicative of a high quality weld, and an alarm is activated when a preselected variation in the measured and the reference quantities occurs. The monitored quantities are also used to calculate additional welding parameters, including heat input, weld bead area and cooling rate. These parameters are also compared to ideal reference values in order to control weld quality. The sensors used for measuring the welding parameters are selected so as to provide minimal interference with the welding process. For example, Hall effect transductors are used for current measurements, while a unique opto-electronic noncontacting sensor is used for measuring the weld speed.

Pathogenesis of a Pichinde Virus Strain Adapted to Produce Lethal Infections in Guinea Pigs

Abstract: A model for studying the pathogenesis of virulent arenavirus infection was developed by adapting Pichinde virus to produce lethal infections of inbred guinea pigs. This adapted Pichinde virus retained low virulence for primates, thus potentially reducing the biohazard to investigators. Whereas all inbred (strain 13) guinea pigs were infected and killed by 3 plaque-forming units or more of adapted Pichinde virus injected subcutaneously, outbred (Hartley strain) guinea pigs were relatively resistant. All infected, inbred guinea pigs died at 13 to 19 days after inoculation, with viremias in excess of 5 log 10 plaque-forming units/ml, severe lymphopenia ( 3 ), and elevated serum glutamic oxaloacetic acid transaminase levels. Immunofluorescent antibody examination of tissues and infectivity titrations of tissue homogenates obtained at 3- to 4-day intervals demonstrated significant viral replication in all visceral tissues examined, but not in brain. Livers of all moribund guinea pigs contained moderate to severe hepatocellular necrosis and diffuse fatty change. Splenic red pulp and adrenal cortical tissues were engorged with blood and contained necrotic foci. Pancreatic acinar tissues were atrophied and vacuolated; lung sections typically contained areas of moderate to severe interstitial pneumonia. Inflammatory cells were conspicuously absent from all lesions. The virological and pathological features of adapted Pichinde infection in guinea pigs are remarkably similar to those described for Lassa virus infections in rhesus monkeys and humans, suggesting that this model might provide insight into the pathogenesis and treatment of Lassa fever in humans. Images

Boresighting of airborne laser designation systems

Abstract: A method and apparatus is described for boresighting the sighting systems ed with a 1.06 micrometer designator laser. The method enables boresighting visual direct view optics, TV, and forward looking infrared (FLIR) sights with respect to the laser itself, without the use of external targets. The laser beam is focused onto a refractory target in the boresight device, creating very briefly an incandescent hot spot which can be "seen" by all three sensors. The radiation from this hot spot is collimated by the boresight device optics and projected back into the sights exactly anti-parallel to the laser beam. By aligning the sight reticles with this hot spot, all three types of sights are aligned relative to the laser. Since the hot flash created by the laser energy is of such short duration, the alignment can be accomplished in flight where relative motion exists between the laser designator system and the boresight module. The apparatus disclosed includes a CO 2 laser alignment fixture and a reflective collimator with a phosphor thermal imaging disk for precision alignment of the laser input and FLIR output lines of sight of the boresight module.

Plaque Assay for Ebola Virus

Abstract: A plaque assay for Ebola virus is reported. The procedure has real potential for future research, although it is less sensitive than indirect fluorescent-antibody and mouse inoculation tests. Images

Protective gel composition for wounds

Abstract: Water soluble hydrogels of alkali metal alginate and glycerine have been found to be excellent wound dressings The gels dry to an adherent, non-toxic pliable protective film which can be removed by water-washing when desired The gels are also compatible with medicaments and hence can serve as vehicles or carriers for medicament application to wounds as well as a protective cover

Ionization of SiO2 by Heavy Charged Particles

Abstract: Highly ionizing heavy charged particles generate significant charge as they pass through the thin thermally grown gate oxide of a MOSFET device. The amount of charge created by an alpha particle and proton is calculated and the yield of charqes which escape initial recombination is measured. The experimental results are shown to agree with a charge recombination model where an ionization track radius of 30-40 A is assumed. Finally, implications of the findings for single charged particle effects in submicron dimension devices are discussed.

Optical properties and mass concentration of carbonaceous smokes

Abstract: Absorption or extinction measurements at wavelengths of 0.5145 and 10.6 μm lead to determination of the mass concentration of carbonaceous smokes with an accuracy of ~20%. The results do not depend on the details of the particle size distribution or on particulate to void ratio.

An experimental study of the circular-polarized elliptical printed-circuit antenna

Abstract: Elliptical-shaped printed-circuit antennas were fabricated with varying eccentricities, and their impedance and radiation patterns were measured. Special attention was devoted to investigating the design criteria which produced the best circular polarization.

Atmospheric modulation transfer function for desert and mountain locations: the atmospheric effects on r 0

Abstract: In conjunction with recent atmospheric modulation transfer function (MTF) measurements for desert and mountain locations, the distribution of optical turbulence within the planetary boundary layer was measured by using tower, aircraft, and acoustic sounder techniques. Diurnal variations in the atmospheric turbulence within 1–3 km above the surface dominate the MTF observations. During convective, daylight hours, desert and mountain boundary layers are found to be similar. The magnitudes of optical turbulence (Cn2) are comparable, and similar thermal plume structures are observed. In addition, optical turbulence is found to have a simple (Δθ)4/3 dependence on the air–surface temperature difference. At night, the cool ground surface produces turbulent, stratified layers above a desert that are not observed for a mountain. The effects of tower height above the ground are investigated theoretically and experimentally. MTF measurements made 2 and 8 m above the desert during the day are in good agreement with theoretical models. We observe interrelationships between the turbulent boundary layer and the atmospheric MTF that can be applied to the selection of both astronomical and solar telescope site locations.