973 resultados para quality requirements
Resumo:
Coke oven liquor is a toxic wastewater produced in large quantities by the Iron and Steel, and Coking Industries, and gives rise to major effluent treatment problems in those industries. Conscious of the potentially serious environmental impact of the discharge of such wastes, pollution control agencies in many countries have made progressively more stringent quality requirements for the discharge of the treated waste. The most common means of treating the waste is the activated sludge process. Problems with achieving consistently satisfactory treatment by this process have been experienced in the past. The need to improve the quality of the discharge of the treated waste prompted attempts by TOMLINS to model the process using Adenosine Triphosophnte (ATP) as a measure of biomass, but these were unsuccessful. This thesis describes work that was carried out to determine the significance of ATP in the activated sludge treatment of the waste. The use of ATP measurements in wastewater treatment were reviewed. Investigations were conducted into the ATP behaviour of the batch activated sludge treatment of two major components of the waste, phenol, and thiocyanate, and the continuous activated sludge treatment of the liquor itself, using laboratory scale apparatus. On the basis of these results equations were formulated to describe the significance of ATP as a measured activity and biomass in the treatment system. These were used as the basis for proposals to use ATP as a control parameter in the activated sludge treatment of coke oven liquor, and wastewaters in general. These had relevance both to the treatment of the waste in the reactor and to the settlement of the sludge produced in the secondary settlement stage of the treatment process.
Resumo:
This review covers the production and utilisation of liquids from the thermal processing of biomass and related materials to substitute for synthetic phenol and formaldehyde in phenol formaldehyde resins. These resins are primarily employed in the manufacture of wood panels such as plywood, MDF, particle-board and OSB. The most important thermal conversion methods for this purpose are fast pyrolysis and vacuum pyrolysis, pressure liquefaction and phenolysis. Many feedstocks have been tested for their suitability as sources of phenolics including hard and softwoods, bark and residual lignins. Resins have been prepared utilising either the whole liquid product, or a phenolics enriched fraction obtained after fractional condensation or further processing, such as solvent extraction. None of the phenolics production and fractionation techniques covered in this review are believed to allow substitution of 100% of the phenol content of the resin without impacting its effectiveness compared to commercial formulations based on petroleum derived phenol. This survey shows that considerable progress has been made towards reaching the goal of a price competitive renewable resin, but that further research is required to meet the twin challenges of low renewable resin cost and satisfactory quality requirements. Particular areas of concern are wood panel press times, variability of renewable resin properties, odour, lack of reactive sites compared to phenol and potential for increased emissions of volatile organic compounds.
Resumo:
A comprehensive examination is made of the characteristics and quality requirements of bio-oil from fast pyrolysis of biomass. An appreciation of the potential for bio-oil to meet a broad spectrum of applications in renewable energy has led to a significantly increased R&D activity that has focused on addressing liquid quality issues both for direct use for heat and power and indirect use for biofuels and green chemicals. This increased activity is evident in North America, Europe, and Asia with many new entrants as well as expansion of existing activities. The only disappointment is the more limited industrial development and also deployment of fast pyrolysis processes that are necessary to provide the basic bio-oil raw material. © 2012 American Institute of Chemical Engineers (AIChE).
Resumo:
Tool life is an important factor to be considered during the optimisation of a machining process since cutting parameters can be adjusted to optimise tool changing, reducing cost and time of production. Also the performance of a tool is directly linked to the generated surface roughness and this is important in cases where there are strict surface quality requirements. The prediction of tool life and the resulting surface roughness in milling operations has attracted considerable research efforts. The research reported herein is focused on defining the influence of milling cutting parameters such as cutting speed, feed rate and axial depth of cut, on three major tool performance parameters namely, tool life, material removal and surface roughness. The research is seeking to define methods that will allow the selection of optimal parameters for best tool performance when face milling 416 stainless steel bars. For this study the Taguchi method was applied in a special design of an orthogonal array that allows studying the entire parameter space with only a number of experiments representing savings in cost and time of experiments. The findings were that the cutting speed has the most influence on tool life and surface roughness and very limited influence on material removal. By last tool life can be judged either from tool life or volume of material removal.
Resumo:
A segment selection method controlled by Quality of Experience (QoE) factors for Dynamic Adaptive Streaming over HTTP (DASH) is presented in this paper. Current rate adaption algorithms aim to eliminate buffer underrun events by significantly reducing the code rate when experiencing pauses in replay. In reality, however, viewers may choose to accept a level of buffer underrun in order to achieve an improved level of picture fidelity or to accept the degradation in picture fidelity in order to maintain the service continuity. The proposed rate adaption scheme in our work can maximize the user QoE in terms of both continuity and fidelity (picture quality) in DASH applications. It is shown that using this scheme a high level of quality for streaming services, especially at low packet loss rates, can be achieved. Our scheme can also maintain a best trade-off between continuity-based quality and fidelity-based quality, by determining proper threshold values for the level of quality intended by clients with different quality requirements. In addition, the integration of the rate adaptation mechanism with the scheduling process is investigated in the context of a mobile communication network and related performances are analyzed.
Resumo:
Only those aggregate sources which have been sampled or tested within the last ten years are listed. This listing additionally ranks sources in accordance with a skid resistance classification as defined herein for aggregates used in asphalt construction. The rankings are based on the ledges used in the past for asphalt aggregates. Upon request, new sources or different combinations of beds within an existing source will be evaluated as to their skid resistance classification. This ranking refers only to the skid resistant properties and does not waive the normal quality requirements for the particular type of aggregate indicated in the contract documents.
Resumo:
Ensihoidossa kysynnän ja kapasiteetin hallinta on toiminnan kriittinen tekijä. Potilaiden hoidontarve asettaa ensihoitopalvelulle varsin tiukat ajalliset ja laadulliset suorituskykyvaatimukset, joista poikkeaminen vaikuttaa suoraan hoidon tuloksiin. Tässä työssä tarkasteltiin ensihoitopalvelun kysynnän ja kapasiteetin hallintaa ennakoitavissa palvelutarpeen muutoksissa. Työn tavoitteena oli kehittää kohdeorganisaation ensihoitopalveluun toimintamalli, jonka avulla se voi nykyistä paremmin tunnistaa normaalista poikkeavat palvelutarpeen muutokset, arvioida niiden vaikutukset ja tarpeet sekä suunnitella ja toteuttaa toiminnan turvallisesti ja tehokkaasti. Työ tehtiin laadullisena toimintatutkimuksena. Empirian osalta työssä perehdyttiin ensihoidon palvelutuotannon vaatimuksiin sekä kohdeorganisaation toimintaan, tarpeisiin ja menetelmiin. Teoriassa tukeuduttiin pääasiassa palvelun kysynnän ja kapasiteetin hallinnan teoriaan. Toimintamallin kehittämisessä hyödynnettiin kohdeorganisaation kokemusta ja asiantuntemusta ratkaisumallien arvioinnissa. Työn tuloksena määriteltiin toimintamalli, jonka avulla kohdeorganisaatio voi systemaattisesti tunnistaa ja analysoida normaalivaihtelusta poikkeavia palvelutarpeen muutoksia, määritellä kysynnän ja kapasiteetin, suunnitella ja toteuttaa toiminnan sekä arvioida ja kehittää menettelyä systemaattisesti.
Resumo:
A qualidade do ar interior (QAI) em edifícios é uma preocupação que acompanha o Homem desde há séculos. A qualidade do ar interior nas escolas, em particular, tem vindo a provocar um crescente interesse, dado que o grupo populacional pertence a um grupo etário mais suscetível de ser afetado. A utilização de ferramentas numéricas de modelação na avaliação da QAI é uma mais valia, pois permite estimar as concentrações dos poluentes no interior dos edifícios. O principal objetivo deste estudo consiste na avaliação da qualidade do ar interior através da aplicação de uma ferramenta a um caso de estudo. Neste caso de estudo estimou-se a concentração de material particulado (PM10) numa sala de aula da Escola Básica nº 1 da Glória, em Aveiro. Neste âmbito, foi aplicado o modelo INDEX, Indoor Exposure model, que possibilita o cálculo de concentrações interiores de poluentes atmosféricos. Os resultados da aplicação indicam que as concentrações do ar interior são influenciadas pelas concentrações exteriores e pela velocidade do vento. Note-se, contudo, que os valores simulados cumprem os valores legislados na Portaria nº 353-A/2013, de 4 de Dezembro. Embora os resultados simulados não revelem uma má qualidade do ar interior na sala de aula da Escola Básica nº 1 da Glória, a avaliação de outros poluentes seria um ponto de extrema importância, de forma a verificar se os requisitos da qualidade do ar interior estarão a ser garantidos.
Resumo:
Background: Ceramic materials are used in a growing proportion of hip joint prostheses due to their wear resistance and biocompatibility properties. However, ceramics have not been applied successfully in total knee joint endoprostheses to date. One reason for this is that with strict surface quality requirements, there are significant challenges with regard to machining. High-toughness bioceramics can only be machined by grinding and polishing processes. The aim of this study was to develop an automated process chain for the manufacturing of an all-ceramic knee implant. Methods: A five-axis machining process was developed for all-ceramic implant components. These components were used in an investigation of the influence of surface conformity on wear behavior under simplified knee joint motion. Results: The implant components showed considerably reduced wear compared to conventional material combinations. Contact area resulting from a variety of component surface shapes, with a variety of levels of surface conformity, greatly influenced wear rate. Conclusions: It is possible to realize an all-ceramic knee endoprosthesis device, with a precise and affordable manufacturing process. The shape accuracy of the component surfaces, as specified by the design and achieved during the manufacturing process, has a substantial influence on the wear behavior of the prosthesis. This result, if corroborated by results with a greater sample size, is likely to influence the design parameters of such devices.
Resumo:
Production companies use raw materials to compose end-products. They often make different products with the same raw materials. In this research, the focus lies on the production of two end-products consisting of (partly) the same raw materials as cheap as possible. Each of the products has its own demand and quality requirements consisting of quadratic constraints. The minimization of the costs, given the quadratic constraints is a global optimization problem, which can be difficult because of possible local optima. Therefore, the multi modal character of the (bi-) blend problem is investigated. Standard optimization packages (solvers) in Matlab and GAMS were tested on their ability to solve the problem. In total 20 test cases were generated and taken from literature to test solvers on their effectiveness and efficiency to solve the problem. The research also gives insight in adjusting the quadratic constraints of the problem in order to make a robust problem formulation of the bi-blend problem.
Resumo:
En el presente documento vamos a explicar el modelo de implementación y ejecución de la empresa Outlanders Colombia, dedicada al ofrecimiento de experiencias de ecoturismo a un público local y extranjero ubicado en Bogotá principalmente caracterizado por ser dinámico y buscar la realización de actividades de contacto con la naturaleza. Para el año 2018 queremos posicionarnos como una empresa referente en nuestro sector por ofrecer servicios de alta calidad en los destinos que abarcamos. Adicionalmente buscaremos concretar la realización de alianzas y acuerdos de cooperación con universidades, ONG´s y demás entidades que puedan ser fuentes de usuarios para nuestras actividades. Por otra parte y aprovechando un eventual escenario de paz en nuestro país, continuaremos con la exploración de lugares de alto atractivo natural en toda Colombia y seguiremos con nuestro modelo de desarrollo de alianzas con operadores y guías turísticos locales que tengan experiencia en la atención al mercado local y se adecúen a la gestión de calidad que planteamos para la prestación de servicios a un público más exigente. Dentro de nuestro portafolio actual ofrecemos productos enmarcados en 4 categorías distintas: Actividades de 1 día, Experiencias en ambientes naturales, recorridos por corredores turísticos y expediciones técnicas. En un futuro cercano desarrollaremos una nueva categoría: Inmersiones etnográficas, en donde pretendemos que nuestro cliente comparta con comunidades indígenas y socialmente lejanas al pensamiento occidental. Para hacer conocer al cliente potencial de nuestros servicios, realizaremos inicialmente caminatas y recorridos gratuitos en donde la gente interesada en actividades outdoor tenga una “muestra gratis” de nuestros servicios. Adicionalmente estamos en proceso de consolidación de alianzas para la promoción de nuestros servicios en entidades con flujo de clientes potenciales: Universidades, ONG´s, colegios, etc. Para complementar nuestra estrategia de publicidad y mercadeo realizaremos una fuerte presencia en redes sociales y canales virtuales de mercadeo. Sabemos de la gran influencia que tiene el componente audiovisual en la promoción de nuestros servicios por lo que nos enfocaremos en mostrar imágenes de lugares con alto atractivo natural por nuestros medios virtuales. Por otra parte sabemos de la importancia de ofrecer un servicio de alta calidad a nuestros turistas, por lo que nos aseguraremos de contar con equipo y personal adecuado para el desarrollo de las actividades. Programas de aseguramiento de la calidad y mejora continua son para nosotros una prioridad. Nuestro equipo inicialmente se compone de dos personas, que se encargan inicialmente de desarrollar labores en las dos principales áreas con las que por el momento cuenta la empresa: Logística y Marketing. Sin embargo para la realización de nuestras actividades contratamos temporalmente (dependiendo de la duración de los viajes) los servicios de expertos, guías y una serie de terceros preferiblemente provenientes de los lugares que visitamos. Actualmente contamos con experiencia en el sector con un acumulado de más de 30 viajes organizados en distintos destinos dentro del país que hacen parte de nuestro portafolio. Nos visualizamos como expertos en la realización de viajes destinos de difícil acceso en el país y así mismo nos queremos posicionar como una empresa ambiental y socialmente responsable con un modelo financiero sostenible.
Resumo:
This work mainly arises from the necessity to support the rapid introduction of different biobased polymers that the industrial sector has been facing lately. Indeed, while considerable efforts are being made to find environmentally and economically sustainable materials, less attention is paid to their need to be properly compounded to fulfil increasingly rigorous technical and quality requirements. Therefore, there is a strong demand for the development of a novel generation of compatible additives able to improve the properties of biobased polymers while respecting sustainability. With this in mind, a new class of biobased plasticizers is herein proposed. Five different ketal-diesters were selectively synthesized starting from levulinic acid, a promising renewable chemical platform. These molecules were added to poly(vinyl chloride) as model polymer to test their plasticizing effectiveness. Complete morphological, thermal and viscoelastic characterizations showed a clear correlation between the structural features of the ketal-esters and the properties of the material. In addition, no significant leaching was found in both hydrophilic and lipophilic environments. Importantly, the proposed ketal-diesters performed comparably and, in some cases, even better than commercial plasticizers. The same molecules were then added to bacterial poly(3-hydroxybutyrate), a semicrystalline polyester characterized by poor thermal and mechanical properties. Morphology assessments showed no phase separation and the plasticizing effectiveness was confirmed by thermal and viscoelastic analyses, while leaching tests showed low extraction values. Readily usable fractions with controlled structure and tailored properties were obtained from highly heterogeneous industrial grade Kraft lignin. These fractions were then added to poly(vinyl alcohol). Promising preliminary results in terms of compatibility were achieved, with thermograms showing only one glass transition temperature. Finally, a fully biobased glycerol-trilevulinate was successfully synthesized by means of a mild and solvent-free route. Its plasticizing effectiveness was evaluated on poly(vinyl chloride), showing a significant decrease of the glass transition temperature of the material.
Resumo:
This study aimed to develop a diet quality index (DQI-a) adjusted for energy requirement. Dietary intake of adults was assessed using 24-hour food recall. The DQI was developed for scores evenly distributed across ten items characterizing different aspects of diet: food groups, nutrients, and variety. The components categorized under the food groups from the Dietary Guide for Brazilians were adjusted according to the estimated energy requirements of the population studied. Index consistency and correlation with nutrients of the diet was analyzed by Cronbach's alpha. A total of 737 individuals were assessed and energy requirements ranged from 1,800 to 2,500kcal among women and 2,500 to 3,400kcal in men. The food group with greatest variation in total portions was cereals and tubers. Cronbach's alpha of the DQI-a was 0.643 and the index correlated with most of the nutrients. The DQI-a can be considered a valuable instrument for assessing diet quality of the Brazilian population.
Resumo:
The DRG classification provides a useful tool for the evaluation of hospital care. Indicators such as readmissions and mortality rates adjusted for the hospital Casemix could be adopted in Switzerland at the price of minor additions to the hospital discharge record. The additional information required to build patients histories and to identify the deaths occurring after hospital discharge is detailed.