MRC Laboratory of Molecular Biology
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A novel split mode TFBAR device for quantitative measurements of prostate specific antigen in a small sample of whole blood
No full textEasy monitoring of prostate specific antigen (PSA) directly from blood samples would present a significant improvement as compared to conventional diagnostic methods. In this work, a split mode thin film bulk acoustic resonator (TFBAR) device was employed for the first time for label-free measurements of PSA concentrations in the whole blood and without sample pre-treatment. The surface of the sensor was covalently modified with anti-PSA antibodies and demonstrated a very high sensitivity of 101 kHz mL ng-1 and low limit of detection (LOD) of 0.34 ng mL-1 in model spiked solutions. It has previously been widely believed that significant pre-processing of blood samples would be required for TFBAR biosensors. Importantly, this work demonstrates that this is not the case, and TFBAR technology provides a cost-effective means for point-of-care (POC) diagnostics and monitoring of PSA in hospitals and in doctors' offices. Additionally, the accuracy of the developed biosensor, with respect to a commercial auto analyser (Beckman Coulter Access), was evaluated to analyse clinical samples, giving well-matched results between the two methods, thus showing a practical application in quantitative monitoring of PSA levels in the whole blood with very good signal recovery
Nonlinear Modal Interactions and Internal Resonance in a Micromachined Disk Resonator
No full textIn this paper, nonlinear modal interactions in a micromachined disk resonator with 2:1 internal resonance are demonstrated. By means of the multiple scales method, two types of transition from stable to unstable behavior including jump phenomena and modulated motion corresponding to M-shaped responses are explained in a coupled nonlinear system dominated by quadratic nonlinearity. At the same time, these exotic responses and stability under different driving forces and the strength of internal resonance are also investigated. Furthermore, the frequency and amplitude stability and signal-to-noise ratio (SNR) can be improved under this condition
Distributed diagnostics, prognostics and maintenance planning: Realizing industry 4.0
No full textIn this paper, a novel distributed yet integrated approach for diagnostics and prognostics is presented. An experimental study is conducted to validate the performance. Results showed that distributed prognostics give better performance in leaser computational time. Also, the proposed approach helps in making the results of the machine learning techniques comprehensible and more accurate. These results will be handy in arriving at predictive maintenance schedule considering the criticality of the system, the dependency of the components, available maintenance resources and confidence level in the results of the prognostic
Silicon Photonic Switch Topologies and Routing Strategies for Disaggregated Data Centers
No full textDisaggregation enabled by silicon photonic switch fabrics is a path to low-cost and energy-efficient data centers. The routing strategy, which can be seamlessly incorporated into the switch control plane, potentially provides an additional dimension for the physical-layer performance optimization, at no extra cost. In this paper, we analyze the role of optical routing strategies for silicon photonic switch fabrics. We define and quantify the number of global switching states in various switching topologies and discuss their relationship to the number of switch permutations. We propose a topology-agnostic approach that is shown to optimize fabric-wide switch path power penalties and consequently reduce the dynamic-range requirement on receivers. Additionally, it potentially compensates for device fabrication variations by taking advantage of the redundancy in switching states over switch permutations; thus, increasing fabrication tolerance. Significant power penalty improvements are demonstrated via both our simulation and test platforms, even for moderate-scale silicon switches
Finite-element modelling of no-insulation HTS coils using rotated anisotropic resistivity
No full textThe no-insulation (NI) winding method is an effective technique for winding coils from high-Tc superconductors (HTS). NI coils are electrically and thermally robust due to their ability to radially bypass current away from the fragile superconducting path when necessary. This avoids stored magnetic energy being entirely discharged on local defects in the HTS tape. However, the increased degrees of freedom for the current distribution makes finite-element modelling of these coils a complicated and multi-level problem. Here we present and validate a 2D axially symmetric model of an NI (or partially insulated) coil that captures all the inherent electromagnetic properties of these coils, including axial vs radial current flow and critical current suppression, and also reproduces the well-known charging and discharging characteristics. The model is validated against previously reported discharge measurements, and is shown to produce results consistent with the expected equivalent-circuit behaviour. Only by solving the NI coil problem with both axial and radial fidelity can the interplay of critical current anisotropy and turn-to-turn current be properly accounted for. The reported FE model will now enable coil designers to simulate key complex behaviours observed in NI coils, such as shielding currents, magnetic field inhomogeneity and remnant field effects
Advanced Gas-cooled reactors technology for enabling molten-salt reactors design - Estimation of coolant impact on neutronic performance
No full textIt has been shown that the Fluoride Salt-Cooled High-Temperature Reactors (FHR) can benefit from adopting some features of well-established Advanced Gas-cooled Reactors (AGR) technology pioneered in the United Kingdom. AGRs offer a number of technological advantages that can potentially speed up the development of FHRs, such as experience with operation at high temperatures, graphite moderated core, fuel design, on-line refuelling, and experience in manufacturing and construction of large concrete pressure vessels with steel liners. This paper summarises relevant information available in the open literature on AGR core operation and design, focusing on neutronic characteristics. The obtained information was used to test the capabilities of Monte Carlo code Serpent to reproduce fuel temperature coefficient of a typical AGR. Then, the paper presents a neutronic analysis of the impact of CO2 coolant substitution with molten salt (FLiBe). The results obtained from the analysis showed that Serpent accurately reproduces the value and behaviour of fuel temperature coefficient both for fresh and depleted fuel conditions. However, subsequent sensitivity and uncertainty analysis showed high uncertainties in the calculated fuel temperature coefficients. The change of the coolant results in significant variation of an AGR neutronic characteristics. The analysis suggests that the use of FLiBe salt as a coolant in AGR-type reactors introduces additional design challenges related to the uncertainties in nuclear data. This work summarises an initial stage of AGRESR project, which was aiming to review the AGR technology relevant to FHR development
Holographic Predictive Search: Extending the scope
No full textHolographic Predictive Search (HPS) is a novel approach to search-based hologram generation that uses a mathematical understanding of the optical transforms to make informed optimisation decisions. Existing search techniques such as Direct Search (DS) and Simulated Annealing (SA) rely on trialling modifications to a test hologram and observing the results. A formula is used to decide whether the change should be accepted. HPS operates presciently, using knowledge of the underlying mathematical relationship to make exact changes to the test hologram that guarantee the'best’ outcome for that change. In this work, we extend the scope of the original research to cover both phase and amplitude modulating Spatial Light Modulators (SLMs), both phase sensitive and phase insensitive systems and both Fresnel and Fraunhofer diffraction. In the cases discussed, improvements of up to 10x are observed in final error and the approach also offers significant performance benefits in generation time. This comes at the expense of increased complexity and loss of generality
A novel energy management strategy for a ship's hybrid solar energy generation system using a particle swarm optimization algorithm
No full textDue to the pressures caused by the energy crisis, environmental pollution, and international regulations, the largest ship-producing nations are exploring renewable resources, such as wind power, solar energy, and fuel cells to save energy and develop more environmentally-friendly ships. Solar energy has recently attracted a great deal of attention from both academics and practitioners; furthermore, the optimization of energy management has become a research topic of great interest. This paper takes a solar-diesel hybrid ship with 5000 car spaces as its research object. Then, following testing on this ship, experimental data were obtained, a multi-objective optimization model related to the ship's fuel economy and diesel generator's efficiency was established, and a partial swarm optimization algorithm was used to solve a multi-objective problem. The results show that the optimized energy management strategy for a hybrid energy system should be tested under different electrical loads. Moreover, the hybrid system's economy should be taken into account when the ship's power load is high, and the output power from the new energy generation system should be increased as much as possible. Finally, the diesel generators' efficiency should be taken into consideration when the ship's electrical load is low, and the injection power of the new energy system should be reduced appropriately
Effect of Pillar Ripple on Static and Dynamic Trade-Offs in Superjunction MOSFETs
No full textMulti-epitaxially grown superjunctions feature a fluctuation of the doping concentration (ripple) in the pillars and the ripple is highly dependent on the supplied thermal energy during the fabrication. This study thoroughly investigates the relationship between the ripple in the pillars and the static/dynamic characteristics of the device. The ripple dependent trade-offs in terms of the specific resistance and turn-off switching loss will be able to provide a guide for developing fine pitch superjunction devices