Burning Surface Temperature Measurements of Propellants and Explosives using Phosphor Thermography

Temperature measurements of propellants and explosives are necessary to create accurate models which lead to better understanding of energetic characteristics such as burning rate. Previous attempts at measuring surface temperatures of burning propellants and explosives using thermocouples have suffered from large uncertainty. Thermographic phosphor thermography employs ceramic powders called phosphors whose spectroscopic properties can be used to remotely and nearly non-intrusively measure temperature. Improved methods were developed for application of this technique to energetic materials to yield more accurate, two-dimensional temperature measurements. In this study, zinc oxide doped with gallium, a thermographic phosphor, was mixed into HMX and RDX powder, two propellant ingredients. These were excited by a laser while burning, and the resulting luminescence was captured by a high-speed camera. The ratio of the intensity of the luminescence at two wavelength bands was measured, and the corresponding temperature dependence was used to determine the surface temperature of the burning materials based on prior calibrations. High precision has been achieved, although further experiments must be performed to validate the accuracy of the data. Methods have been developed to achieve high resolution and more optimal signal strength for this application of phosphor thermography. The experimental data may lead to more accurate accepted values for reacting surface temperatures and improved modeling of these energetic materials

Performance Testing of a Novel Off-plane Reflection Grating and Silicon Pore Optic Spectrograph at PANTER

An X-ray spectrograph consisting of radially ruled off-plane reflection gratings and silicon pore optics was tested at the Max Planck Institute for extraterrestrial Physics PANTER X-ray test facility. The silicon pore optic (SPO) stack used is a test module for the Arcus small explorer mission, which will also feature aligned off-plane reflection gratings. This test is the first time two off-plane gratings were actively aligned to each other and with a SPO to produce an overlapped spectrum. The gratings were aligned using an active alignment module which allows for the independent manipulation of subsequent gratings to a reference grating in three degrees of freedom using picomotor actuators which are controllable external to the test chamber. We report the line spread functions of the spectrograph and the actively aligned gratings, and plans for future development.Comment: Draft Version March 19, 201

Fluid Flow Thermometry Using Thermographic Phosphors

Phosphor thermometry is a non-intrusive thermometry technique that allows for spatially and temporally resolved surface temperature measurements. The thermographic method has been employed in a number of applications that include combustion, sprays, and gas flows. In the current work, we investigate the implementation of thermographic phosphors in liquid flows, which is of interest in a wide range of applications in heat transfer, fluid mechanics, and thermal systems. Zinc oxide doped with Zinc (ZnO:Zn) was the phosphor employed for experimentation due to its high emission intensity and insolubility. In order to explore this application, the phosphor powder was uniformly dispersed in water using a magnetic stirring rod. The phosphor was excited by the third harmonic 355 nm output of a Nd:YAG laser, and the luminescence was examined using a fiber-coupled spectrometer. Analysis of the spectral data showed a significant redshift as the temperature approached boiling point. Further characterization of effects of temperature and experimental parameters such as ZnO:Zn concentration on the luminescence signal was performed

Population synthesis of accreting white dwarfs: Rates and evolutionary pathways of H and He novae

Novae are some of the most commonly detected optical transients and have the potential to provide valuable information about binary evolution. Binary population synthesis codes have emerged as the most effective tool for modelling populations of binary systems, but such codes have traditionally employed greatly simplified nova physics, precluding detailed study. In this work, we implement a model treating H and He novae as individual events into the binary population synthesis code \binaryc. This treatment of novae represents a significant improvement on the `averaging' treatment currently employed in modern population synthesis codes. We discuss the evolutionary pathways leading to these phenomena and present nova event rates and distributions of several important physical parameters. Most novae are produced on massive white dwarfs, with approximately 70 and 55 per cent of nova events occurring on O/Ne white dwarfs for H and He novae respectively. Only 15 per cent of H-nova systems undergo a common-envelope phase, but these systems are responsible for the majority of H nova events. All He-accreting He-nova systems are considered post-common-envelope systems, and almost all will merge with their donor star in a gravitational-wave driven inspiral. We estimate the current annual rate of novae in M31 (Andromeda) to be approximately $41 \pm 4$ for H novae, underpredicting the current observational estimate of $65^{+15}_{-16}$, and $0.14\pm0.015$ for He novae. When varying common-envelope parameters, the H nova rate varies between 20 and 80 events per year.Comment: Accepted, MNRAS. 7 Jun 2020: Minor correction regarding AM CVn masses at period bounce, courtesy of P. Neuteufe

Techno-Economic Feasibility Analysis of a Fully Mobile Radiation Oncology System using Monte Carlo Simulation

PURPOSEDisparities in radiation oncology (RO) can be attributed to geographic location, socioeconomic status, race, sex, and other societal factors. One potential solution is to implement a fully mobile (FM) RO system to bring radiotherapy to rural areas and reduce barriers to access. We use Monte Carlo simulation to quantify techno-economic feasibility with uncertainty, using two rural Missouri scenarios.METHODSRecently, a semimobile RO system has been developed by building an o-ring linear accelerator (linac) into a mobile coach that is used for temporary care, months at a time. Transitioning to a more FM-RO system, which changes location within a given day, presents technical challenges including logistics and quality assurance. This simulation includes cancer census in both northern and southeastern Missouri, multiple treatment locations within a given day, and associated expenditures and revenues. A subset of patients with lung, breast, and rectal diseases, treated with five fractions, was simulated in the FM-RO system.RESULTSThe FM-RO can perform all necessary quality assurance tests as suggested in national medical physics guidelines within 1.5 hours, thus demonstrating technological feasibility. In northern and southeastern Missouri, five-fraction simulations\u27 net incomes were, in US dollars (USD), $1.55 ± 0.17 million (approximately 74 patients/year) and$3.65 USD ± 0.25 million (approximately 98 patients/year), respectively. The number of patients seen had the highest correlation with net income as well as the ability to break-even within the simulation. The model does not account for disruptions in care or other commonly used treatment paradigms, which may lead to differences in estimated economic return. Overall, the mobile system achieved a net benefit, even for the most negative simulation scenarios.CONCLUSIONOur simulations suggest technologic success and economic viability for a FM-RO system within rural Missouri and present an interesting solution to address other geographic disparities in access to radiotherapy

The reporting quality of natural language processing studies: systematic review of studies of radiology reports.

BACKGROUND: Automated language analysis of radiology reports using natural language processing (NLP) can provide valuable information on patients' health and disease. With its rapid development, NLP studies should have transparent methodology to allow comparison of approaches and reproducibility. This systematic review aims to summarise the characteristics and reporting quality of studies applying NLP to radiology reports. METHODS: We searched Google Scholar for studies published in English that applied NLP to radiology reports of any imaging modality between January 2015 and October 2019. At least two reviewers independently performed screening and completed data extraction. We specified 15 criteria relating to data source, datasets, ground truth, outcomes, and reproducibility for quality assessment. The primary NLP performance measures were precision, recall and F1 score. RESULTS: Of the 4,836 records retrieved, we included 164 studies that used NLP on radiology reports. The commonest clinical applications of NLP were disease information or classification (28%) and diagnostic surveillance (27.4%). Most studies used English radiology reports (86%). Reports from mixed imaging modalities were used in 28% of the studies. Oncology (24%) was the most frequent disease area. Most studies had dataset size > 200 (85.4%) but the proportion of studies that described their annotated, training, validation, and test set were 67.1%, 63.4%, 45.7%, and 67.7% respectively. About half of the studies reported precision (48.8%) and recall (53.7%). Few studies reported external validation performed (10.8%), data availability (8.5%) and code availability (9.1%). There was no pattern of performance associated with the overall reporting quality. CONCLUSIONS: There is a range of potential clinical applications for NLP of radiology reports in health services and research. However, we found suboptimal reporting quality that precludes comparison, reproducibility, and replication. Our results support the need for development of reporting standards specific to clinical NLP studies

High Speed X-ray Phase Contrast Imaging of Energetic Composites under Dynamic Compression

Fracture of crystals and frictional heating are associated with the formation of “hot spots” (localized heating) in energetic composites such as polymer bonded explosives (PBXs). Traditional high speed optical imaging methods cannot be used to study the dynamic sub-surface deformation and the fracture behavior of such materials due to their opaque nature. In this study, high speed synchrotron X-ray experiments are conducted to visualize the in situ deformation and the fracture mechanisms in PBXs composed of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) crystals and hydroxyl-terminated polybutadiene binder doped with iron (III) oxide. A modified Kolsky bar apparatus was used to apply controlled dynamic compression on the PBX specimens, and a high speed synchrotron X-ray phase contrast imaging (PCI) setup was used to record the in situ deformation and failure in the specimens. The experiments show that synchrotron X-ray PCI provides a sufficient contrast between the HMX crystals and the doped binder, even at ultrafast recording rates. Under dynamic compression, most of the cracking in the crystals was observed to be due to the tensile stress generated by the diametral compression applied from the contacts between the crystals. Tensile stress driven cracking was also observed for some of the crystals due to the transverse deformation of the binder and superior bonding between the crystal and the binder. The obtained results are vital to develop improved understanding and to validate the macroscopic and mesoscopic numerical models for energetic composites so that eventually hot spot formation can be predicted

Senescence in dahlia flowers is regulated by a complex interplay between flower age and floret position

Mechanisms regulating flower senescence are not fully understood in any species and are particularly complex in composite flowers. Dahlia (Dahlia pinnata Cav.) florets develop sequentially, hence each composite flower head includes florets of different developmental stages as the whole flower head ages. Moreover, the wide range of available cultivars enables assessment of intraspecific variation. Transcriptomes were compared amongst inner (younger) and outer (older) florets of two flower head ages to assess the effect of floret vs. flower head ageing. More gene expression, including ethylene and cytokinin pathway expression changed between inner and outer florets of older flower heads than between inner florets of younger and older flower heads. Additionally, based on Arabidopsis network analysis, different patterns of co-expressed ethylene response genes were elicited. This suggests that changes occur in young inner florets as the whole flower head ages that are different to ageing florets within a flower head. In some species floral senescence is orchestrated by the plant growth regulator ethylene. However, there is both inter and intra-species variation in its importance. There is a lack of conclusive data regarding ethylene sensitivity in dahlia. Speed of senescence progression, effects of ethylene signalling perturbation, and patterns of ethylene biosynthesis gene expression differed across three dahlia cultivars (‘Sylvia’, ‘Karma Prospero’ and ‘Onesta’) suggesting differences in the role of ethylene in their floral senescence, while effects of exogenous cytokinin were less cultivar-specific