X3 expansion tube driver gas spectroscopy and temperature measurements

The University of Queensland’s X3 facility is a large, free-piston driven expansion tube used for superorbital and high Mach number scramjet aerothermodynamic studies. X3’s powerful test flow is initiated by firing its heavy piston into its driver gas – a mixture of argon and helium. Knowledge of the initial and transient temperature behavior of the driver gas is critical to correctly characterize the driver performance, losses and all subsequent expansion tube flow processes. However, the driver gas temperature is not currently measured during routine experimentation and there is limited evidence of its measurement in other international facilities. During recent scramjet flow development in X3, lower than expected experimentally measured shock speeds through helium indicated an effective driver temperature of approximately 2400 K, compared to a temperature of 3743 K at the time of diaphragm rupture for an ideal isentropic driver gas compression. These performance losses motivate this study, which examines initial and peak driver gas temperatures. The study shows that the initial steady-state driver gas temperature, once the filling process ceases, can be approximated by the external driver tube wall temperature. During filling, a net increase in driver gas temperature occurs due to compression heating, as well as, Joule-Thomson effect for helium. Optical emission spectroscopy was then used to resolve the peak driver gas temperature, during piston compression, for a Mach 10 scramjet operating condition. The driver gas emission spectrum exhibits a significant background radiation component, with prominent spectral lines attributed to contamination of the flow. A blackbody approximation of background radiation suggests a peak driver gas temperature of 3200±100 K. Application of the line-ratio method to two argon lines at 763.5 and 772.4 nm suggests a temperature of 3500±750 K. Comparison of these estimates to the ideal isentropic driver gas temperature at diaphragm rupture, 3743 K, suggests losses in the driver gas temperature during the compression process are not extensive for X3, and further that the lower than expected shock speeds are likely primarily due to pressure losses during driver gas expansion through the diaphragm and at the driver-to-driven tube area change

Working group 5: space transportation

The disruption of the traditionally stable launch vehicle market by new commercial players is driving the space transportation sector through its greatest period of change. Although this unprecedented level of growth is aiding in increasing the accessibility of space, it does not come without its challenges. In order to identify, analyse, and address the challenges facing the current and future launch sector, the Space Transportation Working Group at the 2017 Space Generation Congress assessed the existing and incoming stakeholders, their changing needs, and the roles each could play in meeting these challenges.This aim was encapsulated in the following goal statement:Addressing future challenges to foster an economically sustainable launch market,The primary stakeholders in the sector (government space agencies, commercial industry, and launch customers) are undergoing changes in their traditional roles, enabling increasedcooperation. In parallel, upcoming stakeholders, such as academic institutions and nongovernment organisations, may provide support in brokering these developing partnerships. These interactions almost always involve compromise, and from this analysis the following trade off challenges were focused on:1. Innovation and risk2. Global collaboration vs National interestsa. Global collaboration - commercial vs institutionalb. Addressing security issue

The 2018 correlative microscopy techniques roadmap

Developments in microscopy have been instrumental to progress in the life sciences, and many new techniques have been introduced and led to new discoveries throughout the last century. A wide and diverse range of methodologies is now available, including electron microscopy, atomic force microscopy, magnetic resonance imaging, small-angle x-ray scattering and multiple super-resolution fluorescence techniques, and each of these methods provides valuable read-outs to meet the demands set by the samples under study. Yet, the investigation of cell development requires a multi-parametric approach to address both the structure and spatio-temporal organization of organelles, and also the transduction of chemical signals and forces involved in cell-cell interactions. Although the microscopy technologies for observing each of these characteristics are well developed, none of them can offer read-out of all characteristics simultaneously, which limits the information content of a measurement. For example, while electron microscopy is able to disclose the structural layout of cells and the macromolecular arrangement of proteins, it cannot directly follow dynamics in living cells. The latter can be achieved with fluorescence microscopy which, however, requires labelling and lacks spatial resolution. A remedy is to combine and correlate different readouts from the same specimen, which opens new avenues to understand structure-function relations in biomedical research. At the same time, such correlative approaches pose new challenges concerning sample preparation, instrument stability, region of interest retrieval, and data analysis. Because the field of correlative microscopy is relatively young, the capabilities of the various approaches have yet to be fully explored, and uncertainties remain when considering the best choice of strategy and workflow for the correlative experiment. With this in mind, the Journal of Physics D: Applied Physics presents a special roadmap on the correlative microscopy techniques, giving a comprehensive overview from various leading scientists in this field, via a collection of multiple short viewpoints.status: publishe

The 2018 correlative microscopy techniques roadmap

Developments in microscopy have been instrumental to progress in the life sciences, and many new techniques have been introduced and led to new discoveries throughout the last century. A wide and diverse range of methodologies is now available, including electron microscopy, atomic force microscopy, magnetic resonance imaging, small-angle x-ray scattering and multiple super-resolution fluorescence techniques, and each of these methods provides valuable read-outs to meet the demands set by the samples under study. Yet, the investigation of cell development requires a multi-parametric approach to address both the structure and spatio-temporal organization of organelles, and also the transduction of chemical signals and forces involved in cell-cell interactions. Although the microscopy technologies for observing each of these characteristics are well developed, none of them can offer read-out of all characteristics simultaneously, which limits the information content of a measurement. For example, while electron microscopy is able to disclose the structural layout of cells and the macromolecular arrangement of proteins, it cannot directly follow dynamics in living cells. The latter can be achieved with fluorescence microscopy which, however, requires labelling and lacks spatial resolution. A remedy is to combine and correlate different readouts from the same specimen, which opens new avenues to understand structure-function relations in biomedical research. At the same time, such correlative approaches pose new challenges concerning sample preparation, instrument stability, region of interest retrieval, and data analysis. Because the field of correlative microscopy is relatively young, the capabilities of the various approaches have yet to be fully explored, and uncertainties remain when considering the best choice of strategy and workflow for the correlative experiment. With this in mind, the Journal of Physics D: Applied Physics presents a special roadmap on the correlative microscopy techniques, giving a comprehensive overview from various leading scientists in this field, via a collection of multiple short viewpoints