It is quite complicated to evaluate the hazardous waste production and management because the terminology is inconsistent and the legislation differs across countries. This makes it very difficult to compare data among countries and even within the same one. Hence the same data may vary by several tens of percent if they are generated according to different directives. This work deals with evaluation of the production of hazardous waste belonging to the group 20 in Catalogue of wastes. The total production of the hazardous waste from municipalities and citizens (households) is evaluated over a period 2008 - 2011 and the production in the capital city of Prague is for a term of 2006 - 2012. All the types of hazardous waste of the group 20 in Catalogue of wastes cannot be treated individually, due to their high number, and therefore they were arranged into seven groups, which were further processed statistically. The dominant component in both test cases is paint, the total production contains also big amount of electrical waste, fluorescent lamps and batteries. An important part of this work is to compare the composition of household waste originating from three different types of installations - housing estates, mixed and rural. Contrary to my original expectations, the most hazardous waste comes...

"Speech enhancement in an automobile is a challenging problem because interference can come from engine noise, fans, music, wind, road noise, reverberation, echo, and passengers engaging in other conversations. Hands-free microphones make the situation worse because the strength of the desired speech signal reduces with increased distance between the microphone and talker. Automobile safety is improved when the driver can use a hands-free interface to phones and other devices instead of taking his eyes off the road. The demand for high quality hands-free communication in the automobile requires the introduction of more powerful algorithms. This thesis shows that a unique combination of five algorithms can achieve superior speech enhancement for a hands-free system when compared to beamforming or spectral subtraction alone. Several different designs were analyzed and tested before converging on the configuration that achieved the best results. Beamforming, voice activity detection, spectral subtraction, perceptual nonlinear weighting, and talker isolation via pitch tracking all work together in a complementary iterative manner to create a speech enhancement system capable of significantly enhancing real world speech signals. The following conclusions are supported by the simulation results using data recorded in a car and are in strong agreement with theory. Adaptive beamforming, like the Generalized Side-lobe Canceller (GSC), can be effectively used if the filters only adapt during silent data frames because too much of the desired speech is cancelled otherwise. Spectral subtraction removes stationary noise while perceptual weighting prevents the introduction of offensive audible noise artifacts. Talker isolation via pitch tracking can perform better when used after beamforming and spectral subtraction because of the higher accuracy obtained after initial noise removal. Iterating the algorithm once increases the accuracy of the Voice Activity Detection (VAD), which improves the overall performance of the algorithm. Placing the microphone(s) on the ceiling above the head and slightly forward of the desired talker appears to be the best location in an automobile based on the experiments performed in this thesis. Objective speech quality measures show that the algorithm removes a majority of the stationary noise in a hands-free environment of an automobile with relatively minimal speech distortion."

Nas últimas décadas houve um incremento do uso de equipamentos eletroeletrônicos, que têm vida útil determinada por vários fatores, como o porte de equipamento e o comportamento do usuário, por exemplo. Quando estes equipamentos e seus acessórios são descartados tornam-se resíduos de equipamentos eletroeletrônicos (REEE). O objetivo desta tese é selecionar variáveis a serem utilizadas como base de um modelo de previsão de demanda para os REEE. O método de pesquisa adotado foi a pesquisa exploratória combinada com a pesquisa conclusiva, utilizando abordagens de caráter qualitativo e quantitativo. A parte qualitativa utiliza como técnicas de pesquisa a revisão bibliográfica, a revisão sistemática, o grupo focado e as entrevistas. Já em relação à parte quantitativa foram utilizados questionários, ferramentas estatísticas (gráficos e coeficiente de correlação posto-ordem de Spearman) e o método AHP. Foram elaborados cinco artigos científicos, que atingindo objetivos específicos, contribuem para o objetivo geral. O primeiro artigo visava obter informações sobre métodos e ferramentas utilizados para realizar a previsão de demanda de REEE. O segundo artigo pretendia delinear o cenário atual dos REEE do ponto de vista das responsabilidades dos stakeholders no processo de logística reversa. Os riscos e oportunidades decorrentes dos REEE foram abordados no artigo 3, fornecendo informações para o cenário do ponto de vista social, ambiental e econômico. Já o artigo 4 focou nas indústrias de equipamentos eletroeletrônicos do RS e buscou informações sobre a forma de produção, a composição dos produtos e ações destas indústrias para implantação do sistema de logística reversa para os REEE. No último artigo foi definido um conjunto de 21 variáveis que influenciam na logística reversa dos REEE e foi realizada a priorização destas variáveis. Como resultado, foram selecionadas 7 variáveis: estimativa de vida útil do equipamento (1º); Disponibilização de pontos de coleta de REEE (2o); Existência de um acordo setorial (3º); Número de equipamentos vendidos (4º); Incentivos para empresas de reciclagem/gerenciadoras de REEE na região (5º); Existência de empresas de reciclagem ou gerenciadoras de REEE na região (6º); Distância dos pontos de coleta de REEE (7º). / In recent decades there has been an increase in the use of electrical and electronic equipment that have life cycles defined by several factors such as the size of the equipment and user behavior, for example. When this equipment and its accessories are disposed, they become waste electrical and electronic equipment (WEEE). The aim of this doctoral dissertation is to select variables to be used as basis for a demand forecasting model for WEEE. The research method adopted combined exploratory research and conclusive research, with a qualitative and quantitative approach. The following research techniques were used in the qualitative part: literature review, systematic review, focus group and interviews. Regarding the quantitative part, the following techniques were used: questionnaires, statistical tools (graphs and the Spearman’s rank-order correlation coefficient) and the AHP method. Five scientific articles were written, which contributed to the general objective by reaching specific objectives. The first article aimed at obtaining information on methods and tools used to carry out demand forecasting of WEEE. The second article intended to describe the current scenario of WEEE from the perspective of the stakeholders’ responsibility in the process of reverse logistics. The risks and opportunities resulting from WEEE were the theme of the third article, which provided information about the scenario from a social, environmental and economic point of view. The fourth article focused on the factories of electrical and electronic equipment of Rio Grande do Sul, and collected information on the product composition and production methods of such factories, and their actions to implement a system of reverse logistics for WEEE. The last article defined a set of 21 variables that influence the reverse logistics of WEEE, and arranged these variables in order of priority. As a result, seven variables were selected: estimate of life cycle of equipment (1st); Availability of WEEE collection points (2nd); Existence of a sector agreement (3rd); Number of equipment sold (4th); Incentives to WEEE recycling/managing companies in the area (5th); Existence of WEEE recycling or managing companies in the area (6th); Distance between WEEE collection points (7th).

Thesis (Ocean E)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by Joseph Anthony Carnevale, Jr. / Ocean E

The work in this thesis aims to develop new systems for the more efficient recovery of metals from aqueous solution using solvent extraction. Understanding the underlying coordination chemistry to improve hydrometallurgical methods is crucial in order to meet the demand for critical metals for use in modern technologies, reduce the environment impact of recovery from primary mining deposits, and recycle valuable metals from secondary sources (e.g. mobile phones, WEEE). Chapter 2 examines the use of a simple primary amide that can load gold and other chloridometalates into a toluene phase through an outer-sphere mechanism. The loading of a variety of metals/metalloids from varying [HCl] is reported, highlighting the selectivity for gold over other metalates and chloride due to a combination of speciation of those metals and the relative ease of extraction of lower charged species (the Hofmeister bias). The advantages in loading/stripping, toxicity and mass balances compared to commercial alternatives are also outlined, in particular the efficacy of separating gold from a mixed-metal solution representative of those found in WEEE. The mode of action of the primary amide (and secondary/tertiary analogues) is determined using slope analysis, Karl-Fischer water determinations, NMR and MS measurements, EXAFS and computational models. The extraction occurs by the dynamic assembly of multiple amide ligands and gold metalates to generate supramolecular clusters held together through hydrogen-bonding and electrostatic interactions. The secondary and tertiary amides are found to be able to extract monoanionic metalates in a similar manner as the primary amide, although clustering occurs to a lesser extent. Whilst the secondary and tertiary amides are stronger gold extractants than the primary amide, they are not observed to be as successful when extracting from a mixed-metal solution. Instead, a 3rd phase is seen to form from these amides and some metals at higher metal concentrations, which removes the ligands from solution and prevents successful extraction of gold. Chapter 3 builds on an observation in Chapter 2 that a synergistic combination of a simple primary amide and an amine can extract chloridometalates that are typically difficult to solvent extract, such as iridium(III) and rhodium(III). These metalates, complexes with increased anionic charge and varying speciation in aqueous solution, are typically recovered last in a metal production flowsheet. The combination of a primary amide and primary amine was found to be the most effective at extracting the chloridometalates; the strength and strippability of the system is of particular interest in the context of rhodium(III) recovery as this metal currently is not extracted in commercial circuits. The mode of action of the system is investigated using similar techniques to Chapter 2, and reveals that the amine is the more important component of the synergistic mixture compared to the amide, with an improvement in extraction observed when both components are present. Rh(III) is extracted as a mixture of RhCl6 3– and RhCl5(OH2)2– complexes, dependent on the initial [HCl] concentration and the age of the initial aqueous solution. Chapter 4 investigates the feasibility of the recovery of lanthanides as anionic metalates from chloride-, nitrate- or sulfate-rich feeds. Reagents that have been found to be strong chloridometalate extractants, fragmented versions of these, and ‘classic’ commercial outer-sphere reagents are studied. The variations of ligand, anion type and concentration, proton concentration and solvent for the extraction of lanthanides is investigated. However, despite these permutations, no extraction of lanthanides is observed due to the difficulty in extracting more highly hydrated species and the lack of stability of the metalates in aqueous solution.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND AERONAUTICS. / Bibliography: p. 235-239. / by Jere Schenck Meserole, Jr. / Ph.D.

Thesis (M.S.E.C.E.)--University of Delaware, 2007. / Principal faculty advisor: Michael W. Haney, Dept. of Electrical and Computer Engineering. Includes bibliographical references.

The objective of this thesis was to model the Fuzz Face , a transistor-based guitar distortion effect, digitally at the circuit level, and explore how changes in the discrete analog components change the digital model. The circuit was first simulated using SPICE simulation software. Typically outputs and how they changed based on transistor gains were documented. A test circuit was then constructed in lab to determine true transistor gains. An analog Fuzz Face circuit was then constructed, and physical parameters were recorded. A digital model was then created using MATLAB. Capacitive filtering effects were found to be negligible in terms of the guitar signal and were not modeled. The transistors were modeled using the Ebers-Moll equations. A MATLAB algorithm was written to produce Fuzz Face type distortion given an input guitar signal. The algorithm used numerical techniques to solve the nonlinear equations and stored them in a look-up table. This table was used to process the input clips. The sound of the Fuzz Face was not perfectly modeled, but the equations were found to provide a reasonable approximation of the circuit. Further study is needed to determine a more complete modeling equation for the circuit.

Pulse tube refrigerators (PTR) are robust, rugged cryocoolers that do not have a moving component at their cold ends. They are often employed for cryogenic cooling of high performance electronics in space applications where reliability is paramount. Miniaturizing these refrigerators has been a subject of intense research interest because of the benefits of minimal size and weight for airborne operation and because miniature coolers would be an enabling technology for other applications. Despite much effort, the extent of possible PTR miniaturization is still uncertain. To partially remedy this, an investigation of the miniaturization of pulse tube refrigerators has been undertaken using several numerical modeling techniques. In support of these models, experiments were performed to determine directional hydrodynamic parameters characteristic of stacked screens of #635 stainless steel and #325 phosphor bronze wire mesh, two fine-mesh porous materials suitable for use in the regenerator and heat exchanger components of miniature PTRs. Complete system level and pulse tube component level CFD models incorporating these parameters were then employed to quantitatively estimate the effects of several phenomena expected to impact the performance of miniature PTRs. These included the presence of preferential flow paths in an annular region near the regenerator wall and increased viscous and thermal boundary layer thicknesses relative to the pulse tube diameter. The effects of tapering or chamfering the junctions between components of dissimilar diameters were also investigated. The results of these models were subsequently applied to produce successively smaller micro-scale PTR models having total volumes as small as 0.141 cc for which sufficient net cooling was predicted to make operation at cryogenic temperatures feasible. The results of this investigation provide design criteria for miniaturized PTRs and establish the feasibility of their operation at frequencies up to 1000 Hz with dimensions roughly an order of magnitude smaller than those that have recently been demonstrated, provided that challenges related to their regenerator fillers and compressors can be addressed.

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from UMI Company.