| High-Speed, High-Density, Coherent Time Domain Optical Memory |
NOV 91 |
40 pages |
| Authors:
R. Kachru; X-a. Shen; SRI INTERNATIONAL MENLO PARK CA
|
 | Our goal is to quantitatively evaluate the concept of time-domain optical memory (TDOM) based on the stimulated photon echo technique and to prepare for the development of a working prototype. Earlier feasibility studies at SRI International showed that TDOM can store not only digital data in the form a series of on-off laser pulses but also two-dimensional (2-D) images with the same read/write speed. Despite work at SRI and elsewhere, ... |
|
| Thermochemistry of Atmospheric Metal Reactions |
NOV 91 |
48 pages |
| Authors:
K. H. Lau; D. L. Hildenbrand; SRI INTERNATIONAL MENLO PARK CA
|
| As part of a research program carried out during the period May, 1990 through September 1991, we have used effusion-beam mass spectrometry to study the thermochemistry and related aspects of several chemical systems pertinent to the understanding of some atmospheric metal reactions. First, the Na2o-CO2-H 0 system was examined for evidence of gaseous NaHCO3 or other carbonates that may be important as sinks for sodium in the atmosphere. Second, the ... |
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| Development of Electro Supercapacitors |
NOV 91 |
54 pages |
| Authors:
Digby D. Macdonald; Subhash C. Narang; SRI INTERNATIONAL MENLO PARK CA
|
| Nonfluorinated proton conducting superionic molecular tunnel electrolytes (PSMTE) exhibiting high proton conductivity (approximately 10 exp-2 S/cm) have been synthesized. The highly hygroscopic nature of these polymers yielding deliquescent films has precluded their use in supercapacitors. Fluorinated analogs of these PSMTE's were synthesized to provide higher conductivity and greater hydrophobicity. Fluorinated PSMTE's exhibit higher conductivity than Nafion (1.3 x 10 exp-2 vs. 2.1 x 10 exp-4 S/cm) under identical conditions of ... |
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| Data Driven Spatial Reasoning |
OCT 91 |
8 pages |
| Authors:
Prasanna Mulgaonkar; SRI INTERNATIONAL MENLO PARK CA
|
| Our research is aimed at the development of computational techniques for hypothesizing the shapes of hidden portions of unknown objects within a pile of such objects, using a dense range image of the pile. The techniques that we have developed employ symmetry, stability, viewpoint independence, and object impenetrability to hypothesize the unknown shape and dimensions of each visible object. The process constructs alternative hypotheses, which differ in the way the ... |
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| Laboratory Particle Velocity Experiments on Indiana Limestone and Sierra White Granite |
OCT 91 |
76 pages |
| Authors:
S. A. Miller; A. L. Florence; SRI INTERNATIONAL MENLO PARK CA
|
| Laboratory experiments were performed to determine the influence of freezing on the spherical wave generated by a small spherical explosive charge in rock. The work is relevant to the Soviet nuclear test site in Novaya Zemlya where permafrost conditions exist. The results are also valuable for developing and validating material modeling in continuum mechanics codes used for source coupling calculations. The experiments were performed with cores of well characterized Indiana ... |
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| Comparison between Irregularity Motion and Bulk Plasma Drifts at High Latitudes |
OCT 91 |
54 pages |
| Authors:
Robert C. Livingston; Mary C. McCready; SRI INTERNATIONAL MENLO PARK CA
|
| Coincident measurements of ionospheric motion, derived from two different techniques, are compared. The first technique is coherent-scatter radar measurement of bulk plasma drift; if the plasma flow is uniform within its field of view, the radar provides precise measurements of motion resolved from multiple line-of-sight velocity samples. The second technique is spaced-receiver measurement of kilometer-scale irregularity motion; the velocity is extracted from the diffraction pattern produced by integrated propagation effects ... |
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| Knowledge-Based Vision Techniques for the Autonomous Land Vehicle Program |
OCT 91 |
65 pages |
| Authors:
Martin A. Fischler; Robert C. Bolles; SRI INTERNATIONAL MENLO PARK CA
|
| The goal of this research was to develop techniques for automatically acquiring and representing knowledge about complex cultural and natural environments for such purposes as autonomous navigation, planning, intelligence analysis, and manipulation. Our research strategy was to develop representations and techniques for storing (or incrementally learning) semantic and geographic information about a specific geographic area to permit both mission planning and knowledge-based interpretation of sensed data, develop representations for natural ... |
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| Studies of Spatial Inhomogeneities in Smoke Plumes |
30 SEP 91 |
70 pages |
| Authors:
F. L. Ludwig; SRI INTERNATIONAL MENLO PARK CA
|
| Fractal concepts and their relevance to atmospheric processes are reviewed. Among these concepts are approaches to the estimation of fractal dimension based on the slope of the power spectrum, box counting and multidimensional feature analysis. These three approaches were applied to synthesized Brownian fractals, lidar cross sections of an elevated smoke plume, and infrared transmittance imagery of a ground-level smoke plume. The methodologies provided very good estimates of the known ... |
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| Stereospecific Total Synthesis of Radiolabeled Microcystin |
13 SEP 91 |
|
| Authors:
Wesley K. Chong; SRI INTERNATIONAL MENLO PARK CA
|
 | An approach to the total synthesis of the algal toxin microcystin-LR is described herein. Of the seven component amino acids, an enantioselective total synthesis of 3-amino-9-methoxy-10-phenyl-2,3,8-trimethyldeca-4,6-dienoic acid (ADDA) was developed to prepare gram quantities. A structural moiety of the ADDA and D-erythro-Beta-methylaspartic acid (Masp) residues received a lot of synthetic effort, which is continuing. The seven amino acid residues of microcystin-LR were assembled in two ways: fragments of four amino ... |
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| Work Development and Application of Advanced Methods in Electronic Structure to Semiconductors |
13 SEP 91 |
12 pages |
| Authors:
SRI INTERNATIONAL MENLO PARK CA
|
| Work so far falls into a number of groups: (1) continuation of the Schottky barrier studies; (2) work on early stages of Schottky barrier formation (with John Klepeis: (3) work on properties of SiC with Walter Lambrecht and Ben Segall at Case; (4) general development of the methods, most particularly the ultimate electronic structure program that I've design together with Michael Methfessel in Berlin; (5) current projects, and plans for ... |
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| Development of a Therapeutic Agent for Wound-Healing Enhancement |
SEP 91 |
10 pages |
| Authors:
Amrit K. Judd; SRI INTERNATIONAL MENLO PARK CA
|
| During this quarter we synthesized and purified three peptides, one from PDGF A-chain sequence and two from PDGF B-chain sequence. During this quarter we conducted cell binding experiments and assays for mitogenesis. Competitive receptor binding assays were performed on four peptides using NIH 3T3 cells. None of the peptides tested so far showed any binding. We tested two peptides at three doses and two at four doses. In the future, ... |
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| Metaphor and Abduction |
25 AUG 91 |
30 pages |
| Authors:
Jerry R. Hobbs; SRI INTERNATIONAL MENLO PARK CA
|
| In this paper a recent approach to inference in text understanding based on abduction is applied to the problem of metaphor interpretation. The fundamental ideas in the interpretation as abduction approach are outlined. A succinct characterization of interpretation is given, along with a brief example and a description of the principal features of a weighted abduction scheme that is used. This approach is shown to lead to an elegant integration ... |
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| Algorithms for Radio Networks with Dynamic Topology |
AUG 91 |
31 pages |
| Authors:
Nachum Shacham; Richard Ogier; Vladislav V. Rutenburg; Jose Garcia-Luna-Aceves; SRI INTERNATIONAL MENLO PARK CA
|
| The objective of this project was the development of advanced algorithms and protocols that efficiently use network resources to provide optical or nearly optimal performance in future communication networks with highly dynamic topologies and subject to frequent link failures. As reflected by this report, we have achieved our objective and have significantly advanced the state of the art in this area. The research topics of the papers summarized include the ... |
|
| Auroral-Clutter Predictions for Fylingdales, England |
JUL 91 |
30 pages |
| Authors:
Roland T. Tsunoda; SRI INTERNATIONAL MENLO PARK CA
|
| Radar clutter produced by auroral processes in the ionospheric E layer, called auroral clutter, can have severe deleterious effects on surveillance radars that operate in the subauroral regions. Auroral clutter characteristics, however, are practically impossible to characterize with a statistical description because of the large number of controlling parameters. Recently, a predictive code called Comprehensive E-Region Auroral Clutter (CERAC) model has been written that used knowledge of the underlying physics ... |
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| Novel Nonlinear Laser Diagnostic Techniques |
26 JUN 91 |
35 pages |
| Authors:
Gregory W. Faris; Jay B. Jeffries; D. L. Huestis; SRI INTERNATIONAL MENLO PARK CA
|
| This report describes research on novel laser-based diagnostic techniques in two areas: (1) extension of laser-based diagnostics to shorter wavelengths, allowing two-photon detection of atomic ions; and (2) investigation of the feasibility of obtaining quantitative concentration and velocity measurements using amplified spontaneous emission (ASE). For the first task, we have developed a high power VUV source based on two-photon-resonant difference frequency mixing of a ArF excimer laser and a frequency-doubled ... |
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| Ultrafast Laser Techniques |
05 JUN 91 |
69 pages |
| Authors:
H. Helm; C. H. Becker; H. Bissantz; C. Bordas; M. J. Dyer; SRI INTERNATIONAL MENLO PARK CA
|
| A subpicosecond wavelength-tunable high-power dye-laser has been developed and used to perform novel experiments on multiphoton ionization and dissociation, allowing us to draw important conclusions about modifications of the excited state structure of atoms and molecules when exposed to intense radiation. The laser system is based on a synchronously-pumped oscillator, a pulse chirping and compression device, and four amplifiers. The near-Gaussian spatial beam profile and high peak power (>10 GW) ... |
|
| Persistent Data/Knowledge Base |
JUN 91 |
71 pages |
| Authors:
Donovan Hsieh; Teresa Lunt; SRI INTERNATIONAL MENLO PARK CA
|
| The Persistent Data/Knowledge Base (PDKB) project is a research effort funded by Rome Laboratory and conducted at the Computer Science Laboratory of SRI International. The main goal of this effort was to design/ develop persistent object storage techniques capable of handling multiple data objects in a distributed information processing environment. The objective of this effort was to perform an investigation and evaluation and to develop and verify a top level ... |
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| Experimental Investigation of Meteor Burst Footprints, |
JUN 1991 |
|
| Authors:
M. Rich; P. Heilman; M. Murray; B. Yesto; SRI INTERNATIONAL MENLO PARK CA
|
| Meteor Burst Communications (MBC) provides reliable, beyond-line-of-sight data communications, but some serious throughput limitations are associated with the technology. One limitation is the finite waiting time required to send a message. This waiting time can be reduced by increasing the excess link margin, but this increases the cost and complexity of an MBC system. However, because of the limited footprint of a meteor trail, the waiting time for a system ... |
|
| Universal Launcher System |
MAY 91 |
33 pages |
| Authors:
James P. Broady; SRI INTERNATIONAL MENLO PARK CA
|
| The design, fabrication and operation of a Universal Air Gun Launcher System (UAGL) is described. The UAGL uses pressurized inert gas to launch a wide variety of projectiles. The UAGL is a two-man portable system which is capable of launching a 30-lb projectile at a muzzle velocity of 200 ft/s from launch angles of -15 to 105 degrees. |
|
| Systematic Mustard Gas Scavengers. |
17 APR 1991 |
27 pages |
| Authors:
R. Harris III; R. Sanderson; SRI INTERNATIONAL MENLO PARK CA
|
| The synthesis methodology for preparing four types of novel nucleophilic scavengers for experimental treatment of HD intoxication is described. The four types include 3-alkoxyquinuclidines, 4-(dialkyl)aminopyridines, N-alkylpyridine-4-thiones, and imidazoline-2-thiones. A total of 4 compounds representing three of the classes were prepared, characterized, and submitted to WRAIR for biological evaluation. In addition, a convenient kinetic screen to rank target compounds in order of relative reactivity was established. |
|
| Anticholinesterase Therapeutics. |
03 APR 1991 |
|
| Authors:
R. N. Harris III; G. A. Koolpe; R. A. Sanderson; G. A. Peterson; SRI INTERNATIONAL MENLO PARK CA
|
| A total of 27 new experimental therapeutic agents for the treatment of anticholinesterase intoxication were prepared, characterized, and submitted to the Walter Reed Army Institute of Research. Most of the compounds are members of the quaternary 1,2,3-trisubstituted imidazolium ring system. The first precursor to a fused bicyclic, conformationally rigid analog of the imidazolium compounds was prepared in modest yield. Attempts to quaternize 1-methyl-2-(nitro)methylimidazole gave only products resulting from alkylation at ... |
|
| Automated Bathymetric Error Detection Study |
APR 91 |
|
| Authors:
James F. Arnold; Scott W. Shaw; SRI INTERNATIONAL MENLO PARK CA
|
| This report summarizes a program to develop automatic techniques for detecting outliers in multibeam sonar data. Funded as part of an initiative to automate and standardize bathymetry data interpretation, this effort resulted in the implementation, evaluation, and delivery of prototype outlier detection software. When used in conjunction with other productivity tools, automatic outlier editing should significantly reduce the time and expense of bathymetry data preparation. To explore the full range ... |
|
| Improved Muscarinic Antagonists as Anticholinesterase Antidotes |
28 MAR 91 |
54 pages |
| Authors:
Michael Tracy; SRI INTERNATIONAL MENLO PARK CA
|
| Muscarinic antagonists play an important role in anticholinesterase agent therapy by reducing the response of muscarinic receptors to acetylcholine, acting synergistically with cholinesterase reactivators. Therapy with antagonists such as atropine is difficult to manage because of the toxicity of these compounds, atropine antagonizes the receptor whether or not acetylcholine levels are elevated. Our approach to the development of a better antidote is to design a molecule whose concentration and resulting ... |
|
| Modeling of Microstructural Effects on Fracture Processes at High Loading Rates |
MAR 91 |
|
| Authors:
Jacques H. Giovanola; Richard W. Klopp; Donald A. Shockey; SRI INTERNATIONAL MENLO PARK CA
|
| The development of engineered two-phase alloys with tailored mechanical properties requires understanding of the influence of individual phases on properties. For applications involving high loading rates, understanding the rate dependence of mechanical properties is also important. To further this understanding, SRI International is studying (1) the role of microstructure in controlling the static and dynamic fracture properties of the near-beta titanium alloy, Ti-10V-2Fe-3Al, and (2) the role of small compositional ... |
|
| Prophylaxis Against Organophosphonate Intoxication |
15 FEB 91 |
|
| Authors:
Daniel W. Parish; Allen L. Dodge; Robert A. Sanderson; SRI INTERNATIONAL MENLO PARK CA
|
| This report summarizes the technical efforts undertaken for the U.S. Army Medical Research and Development Command (MRDC) under Contract DAMD17-90-C- 0019, Prophylaxis Against Organophosphonate Intoxication , and covers progress during the period 15 December 1989 through 14 December 1990. During this period, 24 compounds were synthesized and submitted to the MRDC for in vivo screening. In addition, three previously submitted compounds, two 1-(1-ARYLCYCLOALKYL) METHYLamines and one bis-quaternary bis(pyridinium) alkane, were ... |
|
| Lower Thermospheric Neutral Densities Determined from Soendre Stroemfjord Incoherent Scatter Radar During LTCS 1 |
01 FEB 91 |
|
| Authors:
K. W. Reese; R. M. Johnson; T. L. Killeen; SRI INTERNATIONAL MENLO PARK CA
|
|
| Ab Initio Molecular Dynamics Simulations of Surfaces and Interfaces |
FEB 91 |
|
| Authors:
Mark van Schilfgaarde; SRI INTERNATIONAL MENLO PARK CA
|
| This work was to develop and apply density-functional methods to semiconductor surfaces and interfaces. The method of Linear Muffin Tin Orbitals (LMTO) was used to make a detailed study of the properties of the ideal metal/ GaAs interface. This was the first systematic study of the properties of a Schottky barrier using a first-principles method, and these explicit calculations shed light on some of the many theories which have been ... |
|
| Calculations of Electron Attachment and Recombination in a Hydrogen Plasma |
FEB 91 |
90 pages |
| Authors:
A. P. Hickman; SRI INTERNATIONAL MENLO PARK CA
|
| This project involved theoretical calculations of microscopic atomic and molecular processes in the generation of H- in a hydrogen plasma. Efficient production of H- is essential for practical applications such as particle beams and fusion plasmas. The specific objectives of the project were: (1) to calculate cross sections foe dissociative recombination of electrons with H2(+) (2) to provide theoretical analysis for ongoing experiments that use multiphoton ionization to investigate the ... |
|
| A Coupled Environment Model for Stress Corrosion Cracking in Sensitized Type 304 Stainless Steel in LWR Environments |
91 |
|
| Authors:
D. D. MacDonald; M. Urquidi-Macdonald; SRI INTERNATIONAL MENLO PARK CA
|
| Intergranular stress corrosion cracking(IGSCC) in sensitized Type 304 stainless steel (SS) in simulated light water reactor(LWR) environments described by physico-electrochemical model differs from previous ones in that internal and external environments are coupled by need to conserve charge in system; solution of Laplce primes equation for external environment, assuming that oxygen reduction on external surfaces consumes positive current emanating from crack mouth, yields a boundary condition for solving Laplace primes ... |
|
| Composition of Surface Films on Nickel Base Superalloys |
91 |
|
| Authors:
Bruce G. Pound; Christopher H. Becker; SRI INTERNATIONAL MENLO PARK CA
|
| The composition and thickness of the passive film formed on three nickel base superalloys (Inconel 718,Incoloy 925 and MP35N) in an acetate buffer was investigated using the technique of surface analysis by laser ionization (SALI); the thickness of the films was found to be similar for the three alloys and was estimated to be 1.5 plus or minus 0.5 nm; the films were all enriched in Cr but were depleted ... |
|
| Dynamic Fracture of Welded Joints |
91 |
|
| Authors:
J. H. Giovanola; R. W. Klopp; S. W. Kirkpatrick; W. W. McDonald; SRI INTERNATIONAL MENLO PARK CA
|
| Experimental testing of the the dynamic fracture if t-shaped welds of a high strength steel were conducted using explosive loading; by changing the thickness of the explosive and density and thickness of the specimen the tests were realiably controlled; scaling the fracture conditions geometrically agreement between the experimental and the analytical results for a rate independent and statistically calibrated local fracture model could be obtained. |
|
| The Strength Behavior of Granulated Silicon Carbide at High Strain Rates and Confining Pressure |
91 |
|
| Authors:
R. W. Klopp; D. A. Shockey; SRI INTERNATIONAL MENLO PARK CA
|
|
| A Detailed Look at Microfailure Processes in a Brittle Matrix Fiber Composite |
91 |
|
| Authors:
T. Kobayashi; D. A. Shockey; S. M. Johnson; SRI INTERNATIONAL MENLO PARK CA
|
| FRASTA (fracture surface topography analysis), a newly developed fractographic technique that shows how a crack front interacts with microstructural features, is described and applied to a continuous fiber- reinforced intermetallic matrix composite. The fracture surfaces of a tensile specimen were examined and their topographies quantified. The fracture process was reconstructed in microscopic detail by comparing the conjugate topographic features at various relative displacements using FRASTA. The results show the sequence ... |
|
| Robust Processing of Real-World Natural-Language Texts |
91 |
24 pages |
| Authors:
Jerry R. Hobbs; Douglas E. Appelt; John Bear; Mabry Tyson; David Magerman; SRI INTERNATIONAL MENLO PARK CA
|
| It is often assumed that when natural language processing meets the real world, the ideal of aiming for complete and correct interpretations has to be abandoned. However, our experience with TACITUS, especially in the MUC-3 evaluation, has shown that principled techniques for syntactic and pragmatic analysis can be bolstered with methods for achieving robustness. We describe and evaluate a method for dealing with unknown words and a method for filtering ... |
|
| SRI International's Tacitus System: MUC-3 Results and Analysis |
1991 |
4 pages |
| Authors:
Jerry R. Hobbs; SRI INTERNATIONAL MENLO PARK CA
|
| This site report is intended as a companion piece to the System Summary appearing in this volume and is best read in conjunction with it. In particular, it refers to the various modules of the system which are described in that paper. Here only the overall results will be summarized. A more detailed, component-by- component analysis of the results is contained in the System Summary. Our results for the TST2 ... |
|
| SRI International: Description of the Tacitus System as Used for MUC-3 |
1991 |
8 pages |
| Authors:
Jerry R. Hobbs; SRI INTERNATIONAL MENLO PARK CA
|
| TACITUS is a system for interpreting natural language texts that has been under development since 1985. It has a preprocessor and postprocessor currently tailored to the MUC-3 application. It performs a syntactic analysis of the sentences in the text, using a fairly complete grammar of English, producing a logical form in first-order predicate calculus. Pragmatics problems are solved by abductive inference in a pragmatics, or interpretation, component. The original purpose ... |
|
| The Use of Prosody in Syntactic Disambiguation |
1991 |
7 pages |
| Authors:
Patti Price; Mari Ostendorf; Stefanie Shattuck-Hufnagel; Cynthia Fong; SRI INTERNATIONAL MENLO PARK CA
|
| Prosodic structure and syntactic structure are not identical; neither are they unrelated. Knowing when and how the two correspond could yield better quality speech synthesis, could aid in the disambiguation of competing syntactic hypotheses in speech understanding, and could lead to a more comprehensive view of human speech processing. In a set of experiments involving 35 pairs of phonetically similar sentences representing seven types of structural contrasts, the perceptual evidence ... |
|
| Theoretical Investigation of Energy Storage in Atomic and Molecular Systems: Metastable Molecular Fuels |
DEC 90 |
46 pages |
| Authors:
Roberta P. Saxon; SRI INTERNATIONAL MENLO PARK CA
|
| Ion-pair species bound by the coulomb attraction between a stable positive and stable negative ion have been investigated theoretically as candidate high-energy fuels that could form the basis of new propulsion schemes. Theoretical results for H3O, Li3H, and H3F are presented along with specific impulse (Isp) predictions based on calculated energies. The ion-pair local minimum on the first excited potential surface of H3O is found to be unstable with respect ... |
|
| Engineering for Artificial Intelligence Software |
DEC 90 |
64 pages |
| Authors:
John Rushby; Mark E. Stickel; Richard J. Waldinger; SRI INTERNATIONAL MENLO PARK CA
|
| Rule based systems are being applied to tasks of increasing responsibility. This report focuses on techniques for the verification and validation of these systems. Conventional software quality assurance depends on the availability of requirements and specification documents. For rule systems, there are generally none because the capabilities of these systems evolve through a development process that is partly experimental in nature. Conventional testing techniques are considered; however, such techniques do ... |
|
| Multilevel Security for Knowledge Based Systems |
DEC 90 |
61 pages |
| Authors:
Teresa F. Lunt; Thomas D. Garvey; SRI INTERNATIONAL MENLO PARK CA
|
| We discuss work aimed at defining a multilevel, mandatory security policy for knowledge based systems. We address two distinct issues: an effective implementation formalism based on a multilevel, object oriented programming paradigm, and requirements for ensuring the corrections of inferences computed on the basis of possibly contradictory information from different access classes. We define requirements for an object-oriented system capable of handling multilevel object with a single access class. We ... |
|
| Advanced Methods of Approximate Reasoning |
30 NOV 90 |
120 pages |
| Authors:
Enrique H. Ruspini; SRI INTERNATIONAL MENLO PARK CA
|
| This research was directed toward establishing basic conceptual foundations for approximate reasoning concepts and toward the development of frameworks that facilitate the development and comparison of applicable techniques. Approximate reasoning is the common name utilized to to describe automated techniques for the representation and manipulation of imprecise, uncertain, unreliable, and vague information. Our attention was focused primarily on the development of conceptual bases for possibilities or fuzzy logic. Using a ... |
|
| Improved Muscarinic Antagonists as Anticholinesterase Antidotes |
21 NOV 90 |
71 pages |
| Authors:
Michael Tracy; SRI INTERNATIONAL MENLO PARK CA
|
| Muscarinic antagonists play an important role in anticholinesterase agent therapy by reducing the response of muscarinic receptors to acetylcholine, acting synergistically with cholinesterase reactivators. Therapy with antagonists such as atropine is difficult to manage because of the toxicity of these compounds; atropine antagonizes the receptor whether or not acetylcholine levels are elevated. Our approach to the development of a better antidote is to design a molecule whose concentration and resulting ... |
|
| Evaluation of a Diffusion/Trapping Model for Hydrogen Ingress in High- Strength Alloys |
14 NOV 90 |
95 pages |
| Authors:
Bruce G. Pound; SRI INTERNATIONAL MENLO PARK CA
|
| The objective of this research was to obtain the hydrogen ingress and trapping characteristics for a range of microstructures and so identify the dominant type of irreversible trap in different alloys. A diffusion/trapping model was used in conjunction with a potentiostatic pulse technique to study the ingress of hydrogen in three precipitation-hardened alloys (Inconel 718, Incoloy 925, and 18Ni maraging steel), two work-hardened alloys (Inconel 625 and Hastelloy C-276), titanium ... |
|
| TACITUS: Text Understanding for Strategic Computing |
NOV 90 |
342 pages |
| Authors:
Jerry R. Hobbs; SRI INTERNATIONAL MENLO PARK CA
|
| The aim of the TACITUS project was to elaborate a theory of how knowledge is used in the interpretation of discourse, and to implement this theory in a computer system for understanding naturally generated texts. This research was carried out between May 1985 and September 1990. The principal results of the research were as follows: 1) The development of a theory of inference in discourse interpretation based on weighted abduction. ... |
|
| Mechanical Properties of Semiconductors and their Alloys |
NOV 90 |
26 pages |
| Authors:
A. Sher; M. A. Berding; M. van Schilfgaarde; S. Krishnamurthy; A. T. Paxton; SRI INTERNATIONAL MENLO PARK CA
|
| This annual report of AFOSR contract F49620-88-K-0009 summarizes the work accomplished on studies of mechanical properties of semiconductors and their alloys, and plastic flow and intermetallic compounds. (1) A simple relationship between the elastic constants of semiconductor is found. (2) A systematic study of tight-binding parameters to fit cohesive energy, bulk modulus, and shear coefficients of all diamond and zinc-blende semiconductors has been carried out. (3) An additional, nonequilibrium mechanism ... |
|
| Spatiotemporal Characteristics of Visual Localization |
NOV 90 |
157 pages |
| Authors:
Christina A. Burbeck; SRI INTERNATIONAL MENLO PARK CA
|
| Psychophysical experiments were conducted to investigate how the human visual system determines the spatial structure of a visual scene. The theoretical basis of the research centers on three ideas: that local spatial filters constitute an initial stage of contrast-encoding; that the properties of these initial filters can affect accuracy of the judgements of the perceived separation; and that the actual encoding of interobject separation occurs at a higher level of ... |
|
| Laboratory Particle Velocity Experiments on (JVE) Analog Rock |
OCT 90 |
105 pages |
| Authors:
S. A. Miller; A. L. Florence; SRI INTERNATIONAL MENLO PARK CA
|
| This project was performed in support of a (DARPA) program to calibrate a Soviet nuclear test site be generating spherical waves in granite obtained from a borehole drilled adjacent to the site of the JVE. Objectives were to determine effects of pore condition and effective stress on spherical wave propagation and attenuation and to investigate coupling and attenuation properties in different low porosity 'hard' rocks to find a suitable analog ... |
|
| Ionic Solid Hydrogen Fuel: Production and Properties of Hydrogen ion and Energetic Neutral Clusters |
SEP 90 |
81 pages |
| Authors:
Young K. Bae; Philip C. Cosby; SRI INTERNATIONAL MENLO PARK CA
|
| we have demonstrated that the production of intense beams of positive hydrogen cluster inos is quite feasible, and should allow their rapid embedment in a H2 matrix. However, stabilization of these species by codeposition of hydrogen cluster anions does not appear to be useful approach, because of the extreme difficulty we have encountered in generating the negative hydrogen cluster beams. Whereas the hydrogen anion clusters may be unstable in the ... |
|
| Explosive Safety Compliance of a Weapon Assembly Operation |
30 Aug 1990 |
32 pages |
| Authors:
Mohsen Sanal; Gary Greenfield; SRI INTERNATIONAL MENLO PARK CA
|
| SRI International evaluated the explosive operations of a weapons assembly operation to determine compliance with the U.S. Department of Defense (DOD) quantity/distance (Q/D) requirements for blast overpressure and fragment projection distance. Figure 1 shows a schematic of the weapon assembly and inhabited buildings. The closest distance between the two buildings (for later use with Q/D charts) is 550 ft. Our objective was to obtain a credible estimate of the hazardous ... |
|
| Drug Development of the Antimalarial Agent Artemisinin: Total Synthesis, Analog Synthesis, and Structure-Activity Relationship Studies |
15 AUG 90 |
|
| Authors:
Mitchell A. Avery; SRI INTERNATIONAL MENLO PARK CA
|
| The enantioselective total synthesis of (+)-artemisinin has been optimized and carried out at multigram scale. An alternate approach to the total synthesis afforded racemic 6, 9-desmethylartemisinin 79 and a related analog 80. A synthetic intermediate from the total synthesis, (+)-acid 32, has been alkylated and led to numerous C-(alkylartemisinin analogs 42 - 63. The acid 32 has also been converted into various N-alkyl amides, which in turn finished 11- azaartemisinin ... |
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Reports by Corporate Author
