Demonstration of a sterilizable solid rocket motor system, addendum

Technical emphasis was placed on characterization of a scaled-up batch of the improved propellant formulation and determination of the effects of dry heat sterilization on propellant integrity and structural response. The grain stress analysis was directed toward tailoring a fully-bonded grain to the calculated propellant allowable stresses and investigating various bond release concepts to relieve stresses incurred in thermal shrinkage following sterilization

Synthesis and alkyne-coupling chemistry of cyclomanganated 1- and 3-acetylindoles, 3-formylindole and analogues

The syntheses are reported of new cyclomanganated indole derivatives (1-acetyl-κO-indolyl-κC2)dicarbonylbis(trimethylphosphite)manganese (2), (1-methyl-3-acetyl-κO-indolyl-κC2)tetracarbonylmanganese (4), (3-formyl-κO-indolyl-κC2)tetracarbonylmanganese (5a) and (1-methyl-3-formyl-κO-indolyl-κC2)tetracarbonylmanganese (5b). The unusually complicated crystal structure of 5b has been determined, the first for a cyclomanganated aryl aldehyde. The preparations of a mitomycin-related pyrrolo-indole and related products by thermally promoted and oxidatively (Me3NO) initiated alkyne-coupling reactions of the previously known complex (1-acetyl-κO-indolyl-κC2)tetracarbonylmanganese (1) are reported for different alkynes and solvents. X-ray crystal structures are reported for the dimethyl acetylenedicarboxylate coupling product of 1 (dimethyl 1-methyl-l-hydroxypyrrolo[1,2a]-indole-2,3-dicarboxylate; 6a), and an unusually-cyclised triple insertion product 8 from the coupling of acetylene with 4, in which a cyclopentadiene moiety is η3-allyl-coordinated to Mn through only one double bond and an exocyclic carbon, but which rearranges on heating to an η5-cyclopentadienyl complex

Predicting functional properties of milk powder based on manufacturing data in an industrial-scale powder plant

The fundamental science relating key physical and functional properties of milk powder to plant operating conditions is complex and largely unknown. Consequently this paper takes a data-driven approach to relate the routinely measured plant conditions to one vital function property known as sediment in an industrial-scale powder plant. Data from four consecutive production seasons was examined, and linear regression models based on a chosen set of processing variables were used to predict the sediment values. The average prediction error was well within the range of the uncertainty of the laboratory test. The models could be used to predict the effect of each individual plant variable on the sediment values which could be beneficial in quality optimisation. In addition the choice of the training data set used to compute regression coefficients was studied and the resultant regression models were compared to alternative PLS models built on the same data

Rapid Particle Size Measurements Used as a Proxy to Control Instant Whole Milk Powder Dispersibility

Characterising the dispersion of instant whole milk powder (IWMP) into water is a complex dissolution measurement that is both manual and laborious so is normally carried out post production at industrial dryers. However, this means there is no immediate feedback so the functional quality cannot be controlled in real-time. This work proposes the idea of applying a simpler, surrogate measurement that can be implemented in the plant in order to have useful real-time information regarding the quality of the product being produced. This we term is a proxy measurement. The functional property dispersibility was used as a case study, with particle size being investigated as a proxy at an industrial IWMP plant. It was found that particle sizing could be used to provide useful information regarding the powder, with the proxy measurement being able to predict in-specification powder 97% of the time. Although the test was not as effective for predicting out-of-specification results, with an false-positive rate of 50%, the fact that out-of-specification events are rare in the industry setting means that the overall proxy measurement is still between 78—87 % accurate, and thus useful for predicting the dispersibility quality of the IWMP. Furthermore, these proxy measurements can then be combined with on-line plant information using multivariate techniques to further improve their accuracy and understand how the quality can be controlled by changing the plant processing conditions

Significance of powder breakdown during in-plant transport at industrial milk powder plants

Instant whole milk powder (IWMP) is designed to rapidly dissolve in water, which depends on the particle size distribution (PSD) and agglomeration. The warm and delicate milk powder exiting the dryer is transported via either pneumatic conveying or bucket elevators to packing. The gentleness of this powder transport process is important for IWMP, as it can break down the agglomerates, generating excess fines, which leads to poor dissolution properties. This work looked at the breakdown of milk powder at two different, geographically separate, industrial IWMP plants, using the Malvern Mastersizer, a laboratory laser diffraction instrument, and sieving, to evaluate the importance of breakdown on the final product properties given different conveying methods. It was found that the method of measurement affected the results, with sieves showing a larger powder size reduction during transport as compared with the Mastersizer. PSDs with a larger average size at the start of powder transport showed more breakdown, with a greater decrease in the average particle size. However, the larger decrease was not enough to compensate for the initially larger average particle size, and powder that started out with larger agglomerates at the fluidised beds still had a larger average particle size at packing. The Mastersizer appeared to break the large agglomerates during measurement, especially with powder that had not been through the entire transport line, thus masking the extent of the size reduction, however this could only occur to weaker agglomerates. Thus in order to produce IWMP with the desired functionalities, the focus should be on improving agglomeration as oppose to reducing transport breakdown to achieve the desired particle size distribution

Spatial and Temporal Variations in Small-Scale Galactic HI Structure Toward 3C~138

We present three epochs of VLBA observations of Galactic HI absorption toward the quasar 3C~138 with resolutions of 20 mas (~ 10 AU). This analysis includes VLBA data from observations in 1999 and 2002 along with a reexamination of 1995 VLBA data. Improved data reduction and imaging techniques have led to an order of magnitude improvement in sensitivity compared to previous work. With these new data we confirm the previously detected milliarcsecond scale spatial variations in the HI opacity at the level of Delta(tau_{max}) =0.50 \pm 0.05. The typical size scale of the optical depth variations is ~ 50 mas or 25 AU. In addition, for the first time we see clear evidence for temporal variations in the HI opacity over the seven year time span of our three epochs of data. We also attempted to detect the magnetic field strength in the HI gas using the Zeeman effect. From this analysis we have been able to place a 3 sigma upper limit on the magnetic field strength per pixel of ~45 muG. We have also been able to calculate for the first time the plane of sky covering fraction of the small scale HI gas of ~10%. We also find that the line widths of the milliarcsecond sizescale HI features are comparable to those determined from previous single dish measurements toward 3C~138, suggesting that the opacity variations cannot be due to changes in the HI spin temperature. From these results we favor a density enhancement interpretation for the small scale HI structures, although these enhancements appear to be of short duration and are unlikely to be in equilibrium.Comment: 34 pages, 8 figures. Figures 3 & 4 are in color. Accepted to A

L-band (3.5 micron) IR-excess in massive star formation, II. RCW 57/NGC 3576

We present a JHKL survey of the massive star forming region RCW 57 (NGC 3576) based on L-band data at 3.5 micron taken with SPIREX (South Pole Infrared Explorer), and 2MASS JHK data at 1.25-2.2 micron. This is the second of two papers, the first one concerning a similar JHKL survey of 30 Doradus. Colour-colour and colour-magnitude diagrams are used to detect sources with infrared excess. This excess emission is interpreted as coming from circumstellar disks, and hence gives the cluster disk fraction (CDF). Based on the CDF and the age of RCW 57, it is possible to draw conclusions on the formation and early evolution of massive stars. The infrared excess is detected by comparing the locations of sources in JHKL colour-colour and L vs. (K-L) colour-magnitude diagrams to the reddening band due to interstellar extinction. A total of 251 sources were detected. More than 50% of the 209 sources included in the diagrams have an infrared excess. Comparison with other JHKL surveys, including the results on 30 Doradus from the first paper, support a very high initial disk fraction (>80%) even for massive stars, although there is an indication of a possible faster evolution of circumstellar disks around high mass stars. 33 sources only found in the L-band indicate the presence of heavily embedded, massive Class I protostars. We also report the detection of diffuse PAHs emission throughout the RCW 57 region.Comment: 15 pages, 13 figure

The Significance of Powder Breakdown During Conveying Within Industrial Milk Powder Plants

Instant whole milk powder (IWMP) is designed to rapidly dissolve in water, which depends on the particle size distribution (PSD). The fragile milk powder exiting the dryer has to be conveyed for packing, which can break down the particles, worsening the dissolution properties. This work investigated the importance of in-plant conveying in determining the nal functional properties at the industrial scale. IWMP breakdown was compared between two plants with di erent transport systems; a pneumatic system and bucket elevator. It was expected that the plant with the bucket elevator consistently produced powder with superior dissolution due to lower breakdown during transport. This was evaluated using the change in PSD. It was found that both plants had a similar decrease in the median particle size, and powder with an initially larger particle size showed more breakdown. However, it was not enough to compensate for the initially larger size. Thus powder that started out larger still had a larger particle size after transport. When quanti ed using the change in bulk density, a low initial bulk density compensated for large breakdown during conveying and ameliorated the impact on the functional properties. Thus in order to produce IWMP with the desired functionalities the focus should be on improving the initial agglomeration, as oppose to reducing transport breakdown.

High-Resolution Continuum Imaging at 1.3 and 0.7 cm of the W3 IRS 5 Region

High-resolution images of the hypercompact HII regions (HCHII) in W3 IRS 5 taken with the Very Large Array (VLA) at 1.3 and 0.7 cm are presented. Four HCHII regions were detected with sufficient signal-to-noise ratios to allow the determination of relevant parameters such as source position, size and flux density. The sources are slightly extended in our ~0.2 arcsecond beams; the deconvolved radii are less than 240 AU. A comparison of our data with VLA images taken at epoch 1989.1 shows proper motions for sources IRS 5a and IRS 5f. Between 1989.1 and 2002.5, we find a proper motion of 210 mas at a position angle of 12 deg for IRS 5f and a proper motion of 190 mas at a position angle of 50 deg for IRS 5a. At the assumed distance to W3 IRS 5, 1.83 +/- 0.14 kpc, these offsets translate to proper motions of ~135 km/s and ~122 km/s$ respectively. These sources are either shock ionized gas in an outflow or ionized gas ejected from high mass stars. We find no change in the positions of IRS 5d1/d2 and IRS 5b; and we show through a comparison with archival NICMOS 2.2 micron images that these two radio sources coincide with the infrared double constituting W3 IRS 5. These sources contain B or perhaps O stars. The flux densities of the four sources have changed compared to the epoch 1989.1 results. In our epoch 2002.5 data, none of the spectral indicies obtained from flux densities at 1.3 and 0.7 cm are consistent with optically thin free-free emission; IRS 5d1/d2 shows the largest increase in flux density from 1.3 cm to 0.7 cm. This may be an indication of free-free optical depth within an ionized wind, a photoevaporating disk, or an accretion flow. It is less likely that this increase is caused by dust emission at 0.7 cm.Comment: 13 pages, 3 figures To be published in The Astrophysical Journa