MRC Laboratory of Molecular Biology
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Development of a deep space nuclear electric propulsion (Nep) system – a nuaer plasma nep reactor
No full textThe application of nuclear fission to meet the propulsion and power requirements of spacecraft has returned to the forefront of research studies in space technology. This project draws on a concept developed by researchers at the University of Florida called a ‘nuclear-activation enhanced’ MHD cycle, in which a partially-ionized rubidium (Rb) vapor from a boiling fast reactor is used to power a magnetohydrodynamic (MHD) generator. In the present study, a molten salt fast reactor concept, called the NuAER plasma NEP-MHD system, is developed based on previous studies of molten salt reactors. A critical reactor core configuration is designed and simulated using the Monte Carlo code SERPENT®. Thermodynamic analysis is performed to assess the feasibility of a Rb vapor MHD cycle with the properties of Rb vapor, at the desired temperatures and pressures, determined from predicted values. Basic heat exchanger calculations are performed to qualify the heat transfer requirements of a simple NuAER plasma NEP reactor concept. The results obtained show that the NuAER plasma NEP-MHD system employing a molten salt fast reactor is a viable fission reactor option for the ‘nuclear-activation enhanced’ MHD cycle
Catheter-integrated soft multilayer electronic arrays for multiplexed sensing and actuation during cardiac surgery
No full textThe rigidity and relatively primitive modes of operation of catheters equipped with sensing or actuation elements impede their conformal contact with soft-tissue surfaces, limit the scope of their uses, lengthen surgical times and increase the need for advanced surgical skills. Here, we report materials, device designs and fabrication approaches for integrating advanced electronic functionality with catheters for minimally invasive forms of cardiac surgery. By using multiphysics modelling, plastic heart models and Langendorff animal and human hearts, we show that soft electronic arrays in multilayer configurations on endocardial balloon catheters can establish conformal contact with curved tissue surfaces, support high-density spatiotemporal mapping of temperature, pressure and electrophysiological parameters and allow for programmable electrical stimulation, radiofrequency ablation and irreversible electroporation. Integrating multimodal and multiplexing capabilities into minimally invasive surgical instruments may improve surgical performance and patient outcomes
24 1x12 wavelength-selective switches using a 312-port 3D waveguide and a single 4k LCoS
No full textA switch module with a 4k LCoS is enabled by a 312-port waveguide array to produce 24 independent 1x12 WSSs. The average/best insertion losses were 8.4/7.2 dB, with crosstalk suppression of 26.9/40.5 dB
Coherent Access: Status and Opportunities
No full textCoherent technology has the potential to be a disruptive technology for access networks. However, deployment of coherent-access remains challenging due to its higher complexity and power-consumption compared with conventional approaches. Herein we review present research status on reduced-complexity coherent PON and outline the future opportunities
Triggers for industrial symbiosis: lessons learnt from twenty-five case studies
No full textThis chapter provides the first part of an evidence base of practices in industrial symbiosis. We reviewed twenty-five case studies to build a rich picture of the various triggers that seed or accelerate resource synergies between organisations. We identified triggers that operate at various levels in relation to industrial symbiosis. These are categorised as national governmental, regional and firm levels. We found that there is a high degree of interplay between these levels. Catalysing industrial symbiosis is complex and context specific. The lessons learnt illuminate the path dependent nature for the scale up of industrial symbiosis
Predictions of the transient loading exerted on circular cylinders by arbitrary pressure waves in air
No full textThis study investigates the transient loading exerted on rigid circular cylinders by impinging pressure waves of arbitrary shape, amplitude and time duration. Numerical calculations are used to predict the transient flow around the cylinder for wide ranges of geometric and loading parameters. An analytical model is developed to predict the transient loading history on the cylinder and this is found to be in good agreement with the results of the numerical calculations. Both models are used to identify and explore the different loading regimes, and to construct non-dimensional maps to allow direct application of the findings of this study to the design of structures exposed to the threat of pressure wave loading
Feedthrough parasitic nonlinear resonance in micromechanical oscillators
No full textMechanical oscillators incorporating miniaturized structures to transduce mesoscopic motion as readable electrical signals are often limited by the feedthrough effect (FE) because oscillation features are corrupted. The knowledge of FE parasitic resonance hitherto is only demonstrated in the linear regime. Herein, we reveal the nature of phenomenological FE parasitic nonlinear resonance. An inverse distortion in the spectra resulting from the superposition of Duffing nonlinearity and the FE is observed and modeled with physical insight into the governing parameters. We find that the manipulation of electromechanical coupling of the oscillator can fully de-embed the FE, while the device oscillates at the nonlinear bifurcation point under phase control. The generic nature of our model indicates that similar dynamic behaviors will occur for the nonlinear resonant systems containing the FE, regardless of transducing techniques. The strategy of on-chip FE control in our capacitive platform is scalable and can be suitably transformed for application in oscillators employing alternative transducers
Effects of ventilation on the indoor spread of COVID-19
No full textAlthough the relative importance of airborne transmission of the SARS-CoV-2 virus is controversial, increasing evidence suggests that understanding airflows is important for estimation of the risk of contracting COVID-19. The data available so far indicate that indoor transmission of the virus far outstrips outdoor transmission, possibly due to longer exposure times and the decreased turbulence levels (and therefore dispersion) found indoors. In this paper we discuss the role of building ventilation on the possible pathways of airborne particles and examine the fluid mechanics of the processes involved
Physics-Based Part Orientation and Sentencing: A Solution to Manufacturing Variability
No full textCasting deviations introduce geometric variability that impacts the aerodynamic performance of turbomachinery. These effects are studied for a high-pressure turbine rotor blade from a modern aero-engine. A sample of 197 blades were measured using structured-light three-dimensional scanning, and the performance of each blade is quantified using Reynolds-averaged Navier-Stokes (RANS) simulations. Casting variation is typically managed by applying geometric tolerances to determine the suitability of a component for service. The analysis demonstrates that this approach may not be optimal since it does not necessarily align with performance, in particular the capacity and efficiency. Alternatively, functional acceptance based on the predicted performance of each blade removes the uncertainty associated with geometric tolerancing and gives better performance control. Building on these findings, the paper proposes a method to set the orientation of the fir-tree, which is machined after casting. By customizing the alignment of each blade, performance variability and scrap rates can be significantly reduced. The method uses predictions of performance to reorient the castings to compensate for manufacturing-induced errors, without changing the design-intent blade geometry and with minimal changes to the manufacturing facility
Experimental Demonstration of in-Service Security Monitoring using a Quantum Modulated Signal
No full text© 2020 OSA. We experimentally demonstrate a method for in-service optical physical layer security monitoring with vacuum-noise sensitivity that can detect a 1% fiber tapping attack at 50km without classical security loopholes