Today, emission legislations for engine exhaust particles are mass based. The engines of today are low-emitting with respect to particle mass, with the emissions approaching the detection limit of the current measurement method. This calls for new and improved measurement methods. Both from the point of view of the engine developers and regarding human health effects, particle number seem to be the particle property of greatest interest to legislate upon. Recently, a proposal for a new particle number based measurement methodology has been put forward by the United Nations Economic Commission for Europe (UN ECE). The gas and particle mixture (the aerosol) of engine exhaust is not a stable system. The size and the number of the particles change over time as the temperature and pressure change. Particle number measurements call for dilution which changes the gas-phase concentrations of the condensing gases. The dilution process alters the conditions in the aerosol and thereby influences the measurements. Within the current project it was desired to better understand the outcome of particle number measurements and the complexities of particle sampling, dilution and conditioning prior to measurements. Two experimental set-ups have been developed within the project. The first system includes a rotating disc diluter followed by a volatility Tandem Differential Mobility Analyser (v-TDMA). The second set-up, called the EMIR-system, includes ejector diluters in series followed by a stand-alone Condensation Particle Counter (CPC). After the development of these experimental set-ups, the v-TDMA has been used to study the volatility and the size distributed number concentration of exhaust particles. The EMIR-system was used for total number concentration measurements including only the solid fraction of the aerosol. The experimental work has given practical experience that can be used to estimate the benefits and disadvantages of upcoming measuring methodology. For the engine developers, in order to produce engines that meet future legislation limits, it is essential to know how the measurement procedure influences the aerosol. In summary, the experimental studies have shown that the number of nucleation mode particles is strongly affected by varied dilution. No upper threshold value of the dilution has been found where the dilution effect diminishes. The volatility studies have shown that it is mainly the nucleation mode particles that are affected by heat. The v-TDMA instrument have shown to be a sensitive analytical tool which, if desired to use for further engine exhaust particle characterization, needs some development work. Experimental work with the EMIR-system, which in principle is similar to the instruments proposed for a future standard, shows that these types of measurement systems are sensitive to small changes in the detector cut-off. The major outcome of the project lies in the new detailed knowledge about particle number measurements from engines. / QC 20100628

Existing and novel laboratory techniques and equipment are used to produce comprehensive information on the liquefaction mitigation provided by granular drainage columnar inclusions in loose sand. Extensive use is made of bender-element testing techniques and the frequency dependence of such measurements is examined. Phase-sensitive detection is proposed as a new method to obtain the frequency response of the element data. The applicability of this technique is extended to provide a convenient and accurate method for determination of the time-of-flight of a shear-wave in sand. This technique is employed to measure the load share between sand and columnar components during triaxial testing. A novel low cost, high loading frequency, triaxial testing system is developed and preliminary testing is carried out on both pure sand samples and composite columnar samples. The testing programme examines aspects of liquefaction mitigation due to the rigidity of the columnar inclusions and due to the increased permeability of the columns. The laboratory results are verified by the application of existing analytical models. The equipment and techniques are used to investigate the feasibility of using recycled aggregates in place of stone backfill.

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The research involves the analysis and design of a new band of horn antennas, namely Frequency Selective Horns (FSHs). Folding a Frequency Selective Surface (FSS) into a shape of a cone makes a FSH. The stimulus behind this research emanates from an idea to use the FSH as a microwave camera for medical diagnostic purposes. FSHs with dipole geometries have been modelled using existing software. A quasi-static approximation models the dipole elements with a dielectric backing as dielectrically loaded cylindrical conducting elements.

Made available in DSpace on 2014-06-11T19:31:34Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-02-02Bitstream added on 2014-06-13T20:22:25Z : No. of bitstreams: 1 dalpai_a_dr_botfca.pdf: 1486803 bytes, checksum: b52df39020b92a64e3e55443e73fcbef (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Universidade Estadual Paulista (UNESP) / No presente trabalho é apresentado um modelo de correção anisotrópico para radiação difusa medida com anel de sombreamento Melo-Escobedo (ME) em função do índice de claridade (razão da radiação global pela extraterrestre). São propostos ainda dois modelos estatísticos da fração difusa isotrópica ( ) e anisotrópica ( ) em função do índice de claridade na estimativa das irradiações horária, diária e mensal. A base de dados das radiações global, direta na incidência e difusa medida pelo anel de sombreamento ME utilizada compreende o período de 1996 a 2002 monitorada pelo Laboratório de Radiometria Solar da UNESP/Botucatu/SP. O modelo de correção anisotrópico, obtido a partir das irradiâncias difusa medida pelo anel de sombreamento Melo-Escobedo (raio 40cm e largura 10cm) e medida pelo método da diferença (referência), considerou três intervalos discretos de por meio de três equações: (0 < < 0,30 - nublado); (0,30 < < 0,65 - parcialmente nublado); e (0,65 < < 1 - aberto). O modelo anisotrópico foi validado comparando-se a irradiância difusa anisotrópica estimada com a irradiância difusa de referência numa base de dados independente, mostrando bons resultados conforme os indicativos estatísticos MBE(%) = 0,25%, 0,51% e -0,38% e RMSE(%)= 5,78%, 9,83% e 12,93% para as coberturas de céu nublado, parcialmente nublado e aberto, respectivamente.... / The present work presents an anisotropic correction model as a function of the clearness index (global/extraterrestrian radiation) for the diffuse radiation measurements with the Melo-Escobedo (ME) shadowring. Two statistical estimate models for the isotropic ( ) and anisotropic ( ) diffuse fraction as a function of clearness index are also proposed to estimate the hourly, daily and monthly diffuse irradiations. The global, diffuse measured by the shadowring ME and the direct radiations measurements were provided by the Laboratory of Solar Radiometry of UNESP/Botucatu/SP in the period from 1996 to 2002. The anisotropic correction model, obtained from the comparison between the diffuse irradiance measured by the Melo-Escobedo shadowring (radius of 40cm and width of 10cm) and the diffuse irradiance measured by the difference method (reference), considered three discreet intervals, with three equations: (0 < <0,30 - cloudy); (0,30 < <0,65 - partially cloudy); and (0,65 < <1 - clear). The anisotropic correction model was validated through the comparison of the anisotropic diffuse irradiance and the reference diffuse irradiance with an independent database, showing good results according to the statistical indicators MBE (%) = 0,25%, 0,51% and -0,38% and RMSE (%) = 5,78%, 9,83% and 12,93% for cloudy, partially cloudy and clear skies, respectively. The anisotropic correction model showed to be dependent of the shadowring dimensions, and for a same radius-width relationship, the smaller radius (20cm) and width (5cm) shadowring needed smaller numeric correction than the larger ray (40cm) and width (10cm) one. The anisotropic correction model was applied in the diffuse irradiance measurements obtained with a 5 minutes frequency automated operating system. The algorithm calculated hourly, daily and monthly anisotropic diffuse irradiations and compared to the ones from the reference diffuse ...(Complete abstract, access undermentioned eletronic address).