The current work was initiated to develop, understand and optimise a novel computer controlled, automated, flexible compression moulding system primarily for the production of fluid seals. A prototype moulding system was designed and built for the study. It was used to process a range of rubber compounds for process evaluation.

The rapid increase in human longevity has raised important questions about what implications this development may have for the variability of age at death. Earlier studies have reported evidence of a historical trend towards mortality compression. However, the period life table model, commonly used to address mortality compression, produces a compressed picture of mortality as a built-in feature of the model. To overcome this limitation, we base our study on an examination of the durations of exposure, in years of age, of birth cohorts and period life tables to selected short ranges of the death rate observed at old age. Overall, old-age mortality has been decompressing, cohort-wise, since the 1960s. This process may further indicate good prospects for ever-decreasing mortality. In the future, deaths may not be concentrated within a narrow age interval, but will instead become more dispersed, though at ever later ages on average.

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Ce travail de recherche porte sur la caractérisation de la réponse mécanique du marbre de Macael sous compression uniaxiale. L objectif à long terme est l intégration de ce marbre dans le domaine de la construction en tant que matériau de soutien. Comme tout matériau hétérogène, le comportement mécanique du marbre calcique est directement lié à la microstructure. Une corrélation entre les événements métamorphiques et la microstructure induite est décrite dans ce travail. L étude géologique associée aux analyses d images, aux études de la texture cristallographique et aux analyses chimiques d échantillons de marbre, a permis de définir les caractéristiques du Volume Elémentaire Représentatif du Blanco de Macael. Pour la caractérisation du comportement sous compression uniaxiale plusieurs essais ont été effectués. Préalablement, une recherche expérimentale sur l influence des conditions d essais sur la réponse mécanique a été accomplie. Enfin, en alliant les mesures acoustiques, les mesures de déformations et les observations des échantillons testés à différentes échelles¡; l initiation, la propagation et la coalescence des mécanismes locaux d endommagement menant à la rupture macroscopique fragile, ont été identifiées. Les essais de compression uniaxiale dans diverses directions, ont démontré un comportement anisotrope du marbre. Trois des caractéristiques de la microstructure régissant cette réponse mécanique ont été distinguées (la morphologie des grains, l orientation cristallographique et les inclusions minérales). Les résultats de ces travaux constituent la base de la conception d un outil numérique de simulation du comportement, en cours de développement. / The research work focuses on the characterization of the mechanical response of Macael s marble under uniaxial compression. The long-term objective is the integration of marble in the construction domain as a support material. Like all heterogeneous material, the mechanical behaviour of calcic marbles is directly linked to the microstructure. A correlation between metamorphic events and the induced microstructure is described in this work. The geological study associated with images analysis, studies of the crystallographic texture and chemical analysis of marble samples, permit to define the characteristics of a Representative Elementary Volume of Blanco de Macael . To characterize the behaviour under uniaxial compression, several tests were carried out. Prior, an experimental research on the influence of test conditions on the mechanical response has been accomplished. Finally, combining acoustic measures, displacement measures and observations of the samples tested at various scales; the initiation, the propagation, and the coalescence of the local damage mechanisms leading to the macroscopic fragile rupture, have been identified. Tests of uniaxial compression in various directions, have demonstrated an anisotropic behaviour of the marble. Three characteristics of the microstructure governing this mechanical response were distinguished (grains morphology, crystal orientation and mineral inclusions). The results of this work constitute the basis for the conception of a numerical tool. The development of the simulation is in progress.

M.Ing. / Pulse Compression is a technique that may be employed for the generation of extremely high amplitude current and voltage pulses. These pulses can be as short as 50 to 100 ns, and may have amplitudes in the kiloampere and kilovolt ranges. Pulse Compression entails the compression of relatively "flat" pulses in the time domain, to pulses of very high amplitudes and extremely short duration. The pulse amplitudes and durations necessary to be achieved in this research, lie in the range where the switching speeds and other parameters of semiconductors are inadequate and where even the working life of conventional gas discharge apparatus are drastically reduced by the extreme switching demands. The burden of excessively high current densities and unmanageable current rise-rates can be transferred from the semiconductor switches to electromagnetic switches, by making use of pulse compression. Pulse compression can be carried out simultaneously or separately for the compression of the current or voltage content of pulses derived from slowly switched sources, to obtain pulses of extremely short duration and very high amplitudes. The main theme of this dissertation is Current compression. Current compression is accomplished through series-resonance in capacitors and saturable inductors connected in a transmission-line configuration. Energy is transferred in this process from one stage to the next, with reduction in pulse-time in each successive stage and a commensurate increase in amplitude. The generated pulses can attain gigawatt amplitudes and nanosecond durations, whilst loading on the semiconducting switches remains low. In addition to design of the pulse-compressor proper, the work also includes design and development of a voltage-controlled pulse power supply, suitable for generating the initial pulses which are to be compressed. Multistage pulse compression is based on the non-linear characteristics of saturable inductors. Dynamic analogue-time simulation is indispensable in a study thereof, as new theory has to be validated and because non-linear analysis is complex and capable only of being executed by employing approximation methods. Because of the difficulties involved, a considerable amount of attention has been devoted to the development of suitable analogue-dynamic simulation programs for execution on a digital computer. A numerical technique has been developed to express non-linear parameters in differential form. This technique makes it possible to model and simulate virtually any non-linear, physically realizable lumped parameter system with ease. The program is based on State Space techniques and has been developed for its versatility, to accomplish the simulation of a wide variety of circuit configurations.

The aim of this study was to evaluate the effect of the type of lubricant, its concentration and mixing time with granules on the tablet hardness, ejection force and the lubrication index. Lactose was used as a filler in granules and polyvinylpyrolidone as a binder. Granules were prepared by wet granulation. Three types of talc were used in concentrations 1%, 3%, 5%, 7% a 10% and magnesium stearate in concetrations 1%, 2% a 3% as lubricants. Tablets were produced by tablet press DOTT Bonapace (model CPR-6) with the possibility to measure the force of the upper and lower punch and force-displacement. These values were used for the calculation of the lubrication index. The values of lubrication index were used for the lubricants comparison. The lubrication index with magnesium stearate did not change either with increasing concentration or with mixing time with granules. In case of each type of talc, the lubrication effect rose with increasing concentration but time of the mixing did not have any significant effect on the lubrication potential. Tablet strength decreased with higher lubricant concentration and longer mixing time when magnesium stearate was used. With increasing concentration of the lubricant tablet strength with talc first increased then stagnated or started to decrease. The higher...

The mechanical properties of a polymer represent the critical characteristics to be considered when determining the applications for it. The same polymer processed with different methods can exhibit different mechanical properties. The purpose of this study is to investigate the difference in mechanical properties of the selected polymers caused by different processing techniques and conditions. Three polymers were studied, including low density polyethylene (LDPE), polypropylene (PP), and NEXPRENE® 1287A. Samples were processed with injection molding and compression molding under different processing condition. Tensile and DMA tests were performed on these samples. The acquired data of strain at break from the tensile tests and storage modulus from the DMA were utilized to calculate brittleness. Calculated brittleness values were used to perform analysis of variance (ANOVA) to investigate the statistical significance of the processing technique and condition. It was found that different processing techniques affect the brittleness significantly. The processing technique is the major factor affecting brittleness of PP and NEXPRENE, and the processing temperature is the major factor affecting brittleness of LDPE.

Context: Data compression is the technique that is used for the fast transmission of the data and also to reduce the storage size of the transmitted data. Data compression is the massive and ubiquitous technology where almost every communication company make use of data compression. Data compression is categorized mainly into lossy and lossless data compression. Ericsson is the telecommunication company that deals with millions of user data and, all these data get compressed using the Deflate compression algorithm. Due to the compression ratio and compression speed, the deflate algorithm is not optimal for the present use case(compress twice and decompress once) of Ericsson. This research is all about finding the best alternate algorithm which suits the current use case so that the deflate algorithm can replace it. Objectives: The objective of the research is to replace the Deflate algorithm with the algorithm, which is useful for compressing the Serving GPRS Support Node-Mobility Management Entity(SGSN-MME) user data effectively. The main objectives to achieve this goal are: Investigating the better algorithm which fits the SGSN-MME compression patterns, investigating the few alternate algorithms for Deflate algorithm, the SGSN- MME dataset used to perform experimentation, the experiment should perform by using all selected algorithms on the dataset, the results of the experiment were compared based on the compression factors, based on the performance of algorithm the Deflate algorithm will get replaced with the suitable algorithm. Methods: In this research, a literature review performed to investigate the alternate algorithms for the Deflate algorithm. After selecting the algorithm, an experiment conducted on the data which was provided by Ericsson AB, Gothenburg and based on the compression factors like compression ratio, compression speed the performance of the algorithm evaluated. Results: By analyzing the results of the experiment, Z-standard is the better performance algorithm with the optimal compression sizes, compression ratio, and compression speed. Conclusions: This research concludes by identifying an alternate algorithm that can replace the Deflate algorithm and also which is suitable for the present Use case.

no / The requirement to efficiently store and process SMILES data used in Chemoinformatics creates a demand for efficient techniques to compress this data. General-purpose transforms and compressors are available to transform and compress this type of data to a certain extent, however, these techniques are not specific to SMILES data. We develop a transform specific to SMILES data that can be used alongside other general-purpose compressors as a preprocessor and post-processor to improve the compression of SMILES data. We test our transform with six other general-purpose compressors and also compare our results with another transform on our SMILES data corpus, we also compare our results with untransformed data.

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