Highly thermally responsive hybrid in-fiber slab waveguide grating structure with a plastic core and a silica cladding

A 1.2(height)×125(depth)×500(length) micro-slot was engraved along a fiber Bragg grating by chemically assisted femtosecond laser processing. By filling epoxy and UV-curing, waveguide with plastic-core and silica-cladding was created, presenting high thermal responding coefficient of 211pm/°C.

Highly thermally responsive hybrid in-fiber sSlab waveguide grating structure with a plastic core and a silica cladding

A 1.2(height)×125(depth)×500(length) micro-slot was engraved along a fiber Bragg grating by chemically assisted femtosecond laser processing. By filling epoxy and UV-curing, waveguide with plastic-core and silica-cladding was created, presenting high thermal responding coefficient of 211pm/°C.

The ecology of percolating filters containing a plastic filter medium in relation to their efficiency in The treatment of domestic sewage

The suitability of a new plastic supporting medium for biofiltration was tested over a three year period. Tests were carried out on the stability, surface properties, mechanical strength, and dimensions of the medium. There was no evidence to suggest that the medium was deficient in any of these respects. The specific surface (320m2m-3) and the voidage (94%) of the new medium are unlike any other used in bio-filtration and a pilot plant containing two filters was built to observe its effects on ecology and performance. Performance was estimated by chemical analysis and ecology studied by film examination and fauna counts. A system of removable sampling baskets was designed to enable samples to be obtained from two intermediate depths of filter. One of the major operating problems of percolating filters is excessive accumulation of film. The amount of film is influenced by hydraulic and organic load and each filter was run at a different loading. One was operated at 1.2m3m-3day-1 (DOD load 0.24kgm-3day-1) judged at the time to be the lowest filtration rate to offer advantages over conventional media. The other filter was operated at more than twice this loading (2.4m3m-3day-lBOD load 0.55kgm-3day-1) giving a roughly 2.5x and 6x the conventional loadings recommended for a Royal Commission effluent. The amount of film in each filter was normally low (0.05-3kgm(3 as volatile solids) and did not affect efficiency. The evidence collected during the study indicated that the ecology of the filters was normal when compared with the data obtained from the literature relating to filters with mineral media. There were indications that full ecological stability was yet to be reached and this was affecting the efficiency of the filters. The lower rate filter produced an average 87% BOD removal giving a consistent Royal Commission effluent during the summer months. The higher rate filter produced a mean 83% BOD removal but at no stage a consistent Royal Commission effluent. From the data on ecology and performance the filters resembled conventional filters rather than high rate filters.

Elastic-plastic analysis of complete building structures

In this Thesis, details of a proposed method for the elastic-plastic failure load analysis of complete building structures are given. In order to handle the problem, a computer programme in Atlas Autocode is produced. The structures consist of a number of parallel shear walls and intermediate frames connected by floor slabs. The results of an experimental investigation are given to verify the theoretical results and to demonstrate various factors that may influence the behaviour of these structures. Large full scale practical structures are also analysed by the proposed method and suggestions are made for achieving design economy as well as for extending research in various aspects of this field. The existing programme for elastic-plastic analysis of large frames is modified to allow for the effect of composite action of structural members, i.e. reinforced concrete floor slabs and the supporting steel beams. This modified programme is used to analyse some framed type structures with composite action as well as those which incorporate plates and shear walls. The results obtained are studied to ascertain the influence of composite action and other factors on the load carrying capacity of both bare frames and complete building structures. The theoretical failure load presented in this thesis does not predict the overall failure load of the structure nor does it predict the partial failure load of the shear walls and slabs but it merely predicts the partial failure load of a single frame and assumes that the loss of stiffess of such a frame renders the overall structure unusable. For most structures the analysis proposed in this thesis is likely to break down prematurely due to the failure of the slab and shear wall system and this factor must be taken into account in any future work on such structures. The experimental work reported in this thesis is acknowledged to be unsatisfactory as a verification of the limited theory proposed. In particular perspex was not found to be a suitable material for testing at high loads, micro-concrete may be more suitable.

Elasto-plastic impact of fine particles and fragmentation of small agglomerates

Surface deposition of dense aerosol particles is of major concern in the nuclear industry for safety assessment. This study presents theoretical investigations and computer simulations of single gas-born U3O8 particles impacting with the in-reactor surface and the fragmentation of small agglomerates. A theoretical model for elasto-plastic spheres has been developed and used to analyse the force-displacement and force-time relationships. The impulse equations, based on Newton's second law, are applied to govern the tangential bouncing behaviour. The theoretical model is then incorporated into the Distinct Element Method code TRUBAL in order to perform computer simulated tests of particle collisions. A comparison of simulated results with both theoretical predictions and experimental measurements is provided. For oblique impacts, the results in terms of the force-displacement relationship, coefficients of restitution, trajectory of the impacting particle, and distribution of kinetic energy and work done during the process of impact are presented. The effects of Poisson's ratio, friction, plastic deformation and initial particle rotation on the bouncing behaviour are also discussed. In the presence of adhesion an elasto-plastic collision model, which is an extension to the JKR theory, is developed. Based on an energy balance equation the critical sticking velocity is obtained. For oblique collisions computer simulated results are used to establish a set of criteria determining whether or not the particle bounces off the target plate. For impact velocities above the critical sticking value, computer simulated results for the coefficients of restitution and rebound angles of the particle are presented. Computer simulations of fracture/fragmentation resulting from agglomerate-wall impact have also been performed, where two randomly generated agglomerates (one monodisperse, the other polydisperse), each consisting of 50 primary particles are used. The effects of impact angle, local structural arrangements close to the impact point, and plastic deformation at the contacts on agglomerate damage are examined. The simulated results show a significant difference in agglomerate strength between the two assemblies. The computer data also shows that agglomerate damage resulting from an oblique impact is determined by the normal velocity component rather than the impact speed.

A production planning system for plastic footwear in a seasonal market

Modern injection-moulding machinery which produces several, pairs of plastic footwear at a time brought increased production planning problems to a factory. The demand for its footwear is seasonal but the company's manning policy keeps a fairly constant production level thus determining the aggregate stock. Production planning must therefore be done within the limitations of a specified total stock. The thesis proposes a new production planning system with four subsystems. These are sales forecasting, resource planning, and two levels of production scheduling: (a) aggregate decisions concerning the 'manufacturing group' (group of products) to be produced in each machine each week, and (b) detailed decisions concerning the products within a manufacturing group to be scheduled into each mould-place. The detailed scheduling is least dependent on improvements elsewhere so the sub-systems were tackled in reverse order. The thesis concentrates on the production scheduling sub-systems which will provide most. of the benefits. The aggregate scheduling solution depends principally on the aggregate stocks of each manufacturing group and their division into 'safety stocks' (to prevent shortages) and 'freestocks' (to permit batch production). The problem is too complex for exact solution but a good heuristic solution, which has yet to be implemented, is provided by minimising graphically immediate plus expected future costs. The detailed problem splits into determining the optimal safety stocks and batch quantities given the appropriate aggregate stocks. It.is found that the optimal safety stocks are proportional to the demand. The ideal batch quantities are based on a modified, formula for the Economic Batch Quantity and the product schedule is created week by week using a priority system which schedules to minimise expected future costs. This algorithm performs almost optimally. The detailed scheduling solution was implemented and achieved the target savings for the whole project in favourable circumstances. Future plans include full implementation.

Acousto-optic modulation in a microstructured plastic optical fibre Bragg grating

The present work addresses the control of the mPOF Bragg grating spectrum properties through acousto-optic modulation. For the first time, the interaction of a flexural acoustic wave, generated by longitudinal excitation of different frequencies, with the Bragg grating will be presented. Also it will be demonstrated the quasi linear relationship between PZT load and maximum reflected power/ 3dB bandwidth of the reflected spectrum.

A transient method of measuring thermal contact conductance between metal-plastic surfaces

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High refractive index plastic optical materials

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