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Voices of Children and Young People in Wales Study: A qualitative study of Wellbeing among children and young people under 25 years old
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Misfit of rigid tools and interferometer subapertures on off-axis aspheric mirror segments
Get PDFRigid tools can confer advantages at certain stages of manufacturing off-axis mirror segments, but the misfit due to surface asphericity and asymmetry poses constraints on their application. Types of misfit are classified and, using least squares, the best-fit tool forms with different distances from the pole of the parent asphere are calculated. The outer mirror segment for the European extremely large telescope is taken as a case-study, assuming a rigid tool size of 150 mm. A simple independent approximation validates the calculation. A close parallel is wavefront misfit in subaperture interferometry, which is also considered
Vibration and buckling of composite beams using refined shear deformation
Get PDFVibration and buckling analysis of composite beams with arbitrary lay-ups using refined shear deformation theory is presented. The theory accounts for the parabolical variation of shear strains through the depth of beam. Three governing equations of motion are derived from the Hamilton’s principle. The resulting coupling is referred to as triply coupled vibration and buckling. A two-noded C1 beam element with five degree-of-freedom per node which accounts for shear deformation effects and all coupling coming from the material anisotropy is developed to solve the problem. Numerical results are obtained for composite beams to investigate effects of fiber orientation and modulus ratio on the natural frequencies, critical buckling loads and corresponding mode shapes
The production of advanced fine-grained alumina by carbon nanotube addition
Get PDFAlumina and alumina+1vol.% carbon nanotube (CNT) composites were fully densified by spark plasma sintering. Post-sintering heat treatments (1300–1500 ◦C) were performed to completely oxidize CNTs and then densify the remaining 1 vol.% to produce fine-grained ceramics. The grain size and Vickers hardness of the heat-treated composites were compared with the monolithic alumina sintered without CNT addition. Compared to the initial powder particle size of alumina (D50: 356±74 nm), minimal grain growth (∼450 nm) was observed for the fully dense heat-treated composites. A 25% improvement in Vickers hardness and >10 times finer average grain size were observed for alumina produced by the heat treatment (1300 ◦C) of alumina+1vol.% CNT composite, compared to alumina sintered without CNTs
Maximising sensory learning through immersive education
Get PDFThe use of simulated learning in nurse education is not new and much has been written regarding various approaches to using low, medium and high-fidelity approaches. Reality or fidelity is important in terms of creating quality learning using simulation; however, within the literature there is a strong focus on the use of computerised mannequins, rather than on the environment in which the simulation occurs. It is accepted that scenarios on which simulation is based should represent the reality of the clinical world, where students are enabled to learn through active participation in situation which they will likely encounter in the real world. Nurses retrieve information from patients using all of their senses; indeed nursing text books advocate the use of a multi-sensory approach to assessment. Using the senses is often highlighted as part of active learning reinforcing the need for seeing, noticing and observing as a central principle; however other senses may be just as important in terms of active learning. Educators need to determine which aspects of clinical simulation are most important for learning. For example, are motor, cognitive and sensory aspects of equal importance? This paper describes the emerging technology enabling educators to introduce a range of sensory learning stimuli, for example, the use of smell as a clinical indicator and sophisticated suits which provide the wearer with tactile feedback. We go on to consider the potential value of such mechanisms to learning through simulation
Use of a NOM profilometer to measure large aspheric surfaces
Get PDFThe use of autocollimator-based profilometers of the Nanometer Optical measuring Machine (NOM) design has been reported for the evaluation of X-ray optics for some time. We report a related development in the use of a non-contact NOM profilometer for the in situ measurement of base radius of curvature and conic constant for E-ELT primary mirror segments during fabrication. The instrument is unusual in NOM design in that it is deployable onto a CNC polishing machine in an industrial fabrication environment. Whilst the measurement of radius of curvature of spherical surfaces over a single scan has been reported previously, here we report on the use of this instrument to measure optical surfaces with an aspheric departure of 180 micrometers using a grid of multiple scans and bespoke surface fitting software. The repeatability of the measurement has been found to be approximately 1 mm in a measured radius of curvature of approximately 90 m. The absolute accuracy is limited by the accuracy of the calibration of the autocollimator and the in situ calibration of the instrument during operation
Instructional laboratory for practical investigation of electric drive control
Get PDFThe study discusses the design principles of instructional laboratory equipment applied for practical investigations of electric drive control. The laboratory workstations comprise of two-motor hardware systems where each motor is controlled by a real-time DSP board. A control structure under test is assembled at the software level using a number of control elements, which is then compiled into a control algorithm for the microcontroller. In order to provide safe test execution, the control algorithm operates under the supervision of a real-time core software ensuring protection of the motors and the power converters. Due to the improvement in the reliability of hardware operation, the rated power of the motors and converters is increased to >1 kW to provide a proper characterisation of electric drives similar to industrial installations. The study also describes the laboratory hardware and software details using an example of the control system for an induction motor based on flux-vector control strategy. The example demonstrates configuring the control systems, compiling it into the execution code, the test procedure and result analysis
A Generalized Method for Efficient Global Optimization of Antenna Design
Get PDFEfficiency improvement is of great significance for simulation-driven antenna design optimization methods based on evolutionary algorithms (EAs). The two main efficiency enhancement methods exploit data-driven surrogate models and/or multi-fidelity simulation models to assist EAs. However, optimization methods based on the latter either need ad hoc low-fidelity model setup or have difficulties in handling problems with more than a few design variables, which is a main barrier for industrial applications. To address this issue, a generalized three stage multi-fidelity-simulation-model assisted antenna design optimization framework is proposed in this paper. The main ideas include introduction of a novel data mining stage handling the discrepancy between simulation models of different fidelities, and a surrogate-model-assisted combined global and local search stage for efficient high-fidelity simulation model-based optimization. This framework is then applied to SADEA, which is a state-of-the-art surrogate-model-assisted antenna design optimization method, constructing SADEA-II. Experimental results indicate that SADEA-II successfully handles various discrepancy between simulation models and considerably outperforms SADEA in terms of computational efficiency while ensuring improved design quality
Estimation of the particle concentration in hydraulic liquid by the in-line automatic particle counter based on the CMOS image sensor
Get PDFModern hydraulic systems should be monitored on the regular basis. One of the most effective ways to address this task is utilizing in-line automatic particle counters (APC) built inside of the system. The measurement of particle concentration in hydraulic liquid by APC is crucial because increasing numbers of particles should mean functional problems. Existing automatic particle counters have significant limitation for the precise measurement of relatively low concentration of particle in aerospace systems or they are unable to measure higher concentration in industrial ones. Both issues can be addressed by implementation of the CMOS image sensor instead of single photodiode used in the most of APC. CMOS image sensor helps to overcome the problem of the errors in volume measurement caused by inequality of particle speed inside of tube. Correction is based on the determination of the particle position and parabolic velocity distribution profile. Proposed algorithms are also suitable for reducing the errors related to the particles matches in measurement volume. The results of simulation show that the accuracy increased up to 90 per cent and the resolution improved ten times more compared to the single photodiode sensor
Real-time model of switched reluctance drive based on a LUT magnetization curve for educational purposes
Get PDFThis paper discusses the implementation of a real-time model of a switched reluctance motor drive for which the parameters of its magnetisation curve are represented by the data in a look-up table. A method of cubic interpolation has been applied for the look-up table approximation in order to provide a high accuracy and realistic performance of the modelled motor drive. The model structure has been optimised for real-time execution in a motion control microcontroller operating under PWM frequency up to 40 kHz. The model is designed to be used in the students' coursework on the specialist subject of electric drive control