The performance of a distributed combat simulation with the time warp operating system

This paper analyzes the performance of a discrete-event combat simulation executed on a parallel processor under control of the Time Warp Operating System. Time Warp is in a class of distributed simulation methods called Optimistic methods which have proven to be useful over a wide range of simulations. The combat simulation used for this performance study, called STB88, is a division-corps model incorporating a number of different types of computations. The speed-up for three versions of this model on the Caltech/JPL Mark III Hypercube and the BBN Butterfly parallel processors was measured relative to an efficient sequential execution of the same model on the same hardware. The results indicate that STB88 version 1 achieves a speed-up of 28.6 on 60 Mark III processors, while STB88 version 2 achieves a speed-up of 36.8 on 100 Butterfly processors. Version 3 of STB88 achieved a speed-up of 38.5 on 128 Mark III processors. The versions differed only in their interface to Time Warp. On the Butterfly, the sequential execution completed in 2 hours, while the 100 processor execution completed in 3.2 minutes.     

Radiation-curable carbon fiber prepreg composites

Radiation processing is the utilization of ionizing radiation, usually photons or electron beams, to produce useful physical and chemical changes in a material. A potential application for electron beam processing for composite manufacturing is for curing carbon fiber prepregs. These prepregs, carbon fibers or fabrics preimpregnated with liquid polymer resin, are commonly used in the aircraft industry. Their use, however, can be time consuming and labor intensive. The advantages of radiation curing over thermal or chemical curing methods include improved rate control, reduced curing times, and curing at ambient temperature. There is no need for chemical initiators. A radiation-curable prepreg has been designed to meet the mechanical and physical property specifications of a leading aircraft manufacturing company. The resin is a mixture of an expoxy diacrylate, polybutadiene diacrylate, and a multifunctional monomer. This resin was used to impregnate a plain weave carbon fabric, at a loading of 35 percent (by mass), using a solvent process. Preliminary characterization studies show that the cured polymer produced by irradiation in air to a dose of 40 kGy is amorphous with a maximum gel fraction of 85 percent. The softening point of the polymer varied from 228°C (30-kGy sample) to 237°C (50-kGy sample). The linear thermal expansion coefficient of the polymer was 1.7 × 10⁻⁴ m/m°C from 25°C to 150°C and was unaffected by varying the applied dose from 30 to 50 kGy.     

Synthesis and Field Tests of Possible Minor Components of the Sex Pheromone of Prionus californicus

Earlier work has shown that adult male Prionus californicus Motschulsky (Coleoptera: Cerambycidae) are attracted to the female-produced compound (3R,5S)-3,5-dimethyldodecanoic acid, and to a synthetic mixture of the four stereoisomers of 3,5-dimethyldodecanoic acid. Here, we report the results of field trials that tested whether or not three structurally related compounds (methyl 3,5-dimethyldodecanoate, 3,5-dimethyltridecanoic acid, and 3,5-dimethylpentadecanoic acid), present in extracts of virgin females, are attractive, and whether or not they influence attraction to 3,5-dimethyldodecanoic acid. In a trial with single components, only traps baited with the acid or its methyl ester captured more beetles than did control traps; catches to the acid were five times higher than to the methyl ester. Another trial, excluding 3,5-dimethyldodecanoic acid, confirmed the activity of the methyl ester. Finally, addition of the three compounds to 3,5-dimethyldodecanoic acid, in the ratio found in extracts from female beetles, gave a catch similar to that of traps baited with 3,5-dimethyldodecanoic acid alone. Consequently, the function of these minor compounds remains undetermined.     

Physical and Chemical Processes to Enhance Oil Recovery from Condensed Corn Distillers Solubles

Oil recovery from corn fermentation co-products can provide feedstock for biodiesel production. The effects of physical and chemical processes on oil recovery from condensed corn distillers solubles (CCDS) were investigated. Heating disrupted physical interactions in the CCDS and increased oil recovery by 2.5-fold when temperature was increased from 25 to 59 °C. Oil recovery at acidic pH conditions was significantly greater than at alkaline pH. Oil recovery at alkaline pH was increased by heating and addition of the reducing agent, sodium metabisulfite. Oil extraction using polar solvents isopropanol and butanol achieved greater than 80% oil recovery. When oil was co-extracted with zein using hexane and ethanol as co-solvents, the greatest total oil recovery was achieved, 89%. Churning CCDS at pH 3.5, 50 °C for 3 h achieved up to 80% oil recovery. This study provides data for designing further effective methods for oil separation from corn ethanol co-products.     

Behavior of Pt Atoms on Oxide Supports During Reduction Treatments at Elevated Temperatures,Characterized by Aberration Corrected Stem Imaging

Abstract  

Aberration-corrected scanning transmission electron microscopy at the sub-?ngstr?m resolution allows imaging the structure of catalytic materials at the single atom level and permits fundamental studies of the behavior of heavy metal catalytic species as a result of elevated temperature gas-treatments. The present study is aimed at understanding the development of clusters and nanoparticles of Pt on γ-alumina during reduction treatments of a pre-oxidized highly dispersed catalyst. A special built ex situ reactor and a specimen holder allowing cyclic anaerobic transfer between the reactor and microscope were used for the study. The number of atoms in a nascent cluster can be determined along with the general shape of the cluster. Reduction experiments without air exposure of the sample showed that although clusters are formed at 500 °C, many Pt atoms are not associated with the cluster and are still dispersed on the catalyst support. After a 700 °C reduction, all of the Pt atoms are associated with the clusters. Movement of the clusters on the catalyst support is different depending upon the catalyst support.     

An adaptable luminescence resonance energy transfer assay for measuring and screening protein-protein interactions and their inhibition

Protein-protein interactions (PPIs) are central to biological processes and represent an important class of therapeutic targets. Here we show that the interaction between FK506-binding protein 12 fused to green fluorescent protein (GFP-FKBP) and the rapamycin-binding domain of mTor fused to Escherichia coli dihydrofolate reductase (FRB-eDHFR) can be sensitively detected (signal-to-background ratio (S/B)>100) and accurately quantified within an impure cell lysate matrix using a luminescence resonance energy transfer (LRET) assay. Ascomycin-mediated inhibition of GFP-FKBP-rapamycin-FRB-eDHFR complex formation was also detected at high S/B ratio (>80) and Z'-factor (0.89). The method leverages the selective, stable binding of trimethoprim (TMP)-terbium complex conjugates to eDHFR, and time-resolved, background-free detection of the long-lifetime (～ms) terbium-to-GFP LRET signal that indicates target binding. TMP-eDHFR labeling can be adapted to develop high-throughput screening assays and complementary, quantitative counter-screens for a wide variety of PPI targets with a broad range of affinities that may not be amenable to purification.     

Modelling collisions of soft agglomerates at the continuum length scale

Growth and breakdown mechanisms in granulation processes may involve collisions between soft plastically deforming agglomerates. It has been established previously that the flow stress in such collisions increases with the strain rate, which is dependent on the impact velocity and the size of the agglomerates. In the current paper, a scaling model is described that is based on a continuum constitutive relationship and formulated in terms of accessible experimental parameters. It is an extension of an existing contact mechanics model for elastoplastic nonadhesive collisions and therefore limited to deformations in which the contact radius is less than about 40% of the agglomerate radius. In addition, it is assumed that the elastic strains are small compared to the maximum value. Finite element simulations were carried out for a range of impact velocities and material parameters associated with an elastoviscoplastic constitutive relationship of the type used in the scaling model. The results were employed to validate the scaling model. Within the specified limits of applicability, it was found that the coefficient of restitution, contact area, loading and unloading curves and also the time evolution of the compressive displacement could be calculated with relatively high accuracy. Moreover, it was found that for a viscoplastic material the rate of decrease of the coefficient of restitution with increasing impact velocity is greater than for plastic deformation. The model should prove useful in understanding collision processes in granulation systems, particularly those occurring at relatively high impact velocities when the main energy dissipation process arises from viscoplastic deformation. Under this circumstance, the influence of adhesion is negligible and coalescence may be taken to occur when the coefficient of restitution is small.     

Anthraquinone Losses During Alkaline Pulping

Extensive loss of anthraquinone (AQ) or the active catalyst anthrahydroquinone (AHQ) from the AQ –- AHQ catalytic cycle has been explained in part by side reactions leading to the reaction product anthrone (anthracen-9-one), followed by subsequent formation of adducts with lignin quinone methides. Degradation of an adduct between anthrone and the quinone methide of guaiacylglycerol-β-guaiacyl ether, under soda pulping conditions, resulted in a complex mixture of products. The mixture included 3-guaiacylbenzanthrone, bianthronyl, bianthrone, guaiacol, AQ, trans-coniferyl alcohol, trans-coniferylaldehyde, cis- and trans-1-(3-methoxy-4-hydroxyphenyl)-2-(2-methoxyphenoxy)ethene, vanillin, and 2-methoxy-4-vinylphenol. C-13 NMR studies of lignins isolated from soda/AQ spent liquors indicated the presence of residual anthrone adducts and a significant content of chemically attached AQ.