219 research outputs found

    On the construction of hierarchic models

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    One of the main problems in the field of model-based diagnosis of technical systems today is finding the most useful model or models of the system being diagnosed. Often, a model showing the physical components and the connections between them is all that is available. As systems grow larger and larger, the run-time performance of diagnostic algorithms decreases considerably when using these detailed models. A solution to this problem is using a hierarchic model. This allows us to first diagnose the system using an abstract model, and then use this solution to guide the diagnostic process using a more detailed model. The main problem with this approach is acquiring the hierarchic model. We give a generic hierarchic diagnostic algorithm and show how the use of certain classes of hierarchic models can increase the performance of this algorithm. We then present linear time algorithms for the automatic construction of these hierarchic models, using the detailed model and extra information about cost of probing points and invertibility of components

    Economic feasibility of second generation ethanol with and without indirect greenhouse gas reduction benefits : a simulation for Brazil

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    The aim of this study is to determine the economic feasibility of second generation ethanol from sugar cane, whereby traditional ethanol production is combined with the use of lignocellulosic biomass for ethanol production. By applying cost-benefit analysis, this study evaluated the viability of the second generation ethanol technology as an alternative to conventional sugarcaneto- ethanol, both in terms of processing technology, and of land use impacts. Furthermore, an attempt is made to analyze impacts on CO2 mitigation and land use in economic. The research results indicate that: i) from an economic point of view, the first generation plant is clearly preferable. With IRR of 18.7%, Minimum selling price of US0.31perliter,andNPVofUS 0.31 per liter, and NPV of US 213.0 million, first generation ethanol production from sugar cane has a large economic advantage compared to the second generation plant (IRR of 13.5%, Minimum selling price of US0.40perliterandNPVofUS 0.40 per liter and NPV of US 78.5 million). ii) from an environmental point of view, a second generation biofuel that makes use of lignocellulosic biomass plant is clearly preferable. The second generation plant uses 49.6% less land and avoids a CO2 debt average of 942,282 ton per year throughout the life of the project. iii) Productivity gains improve profitability (IRR) and reduce biofuel prices (Minimum selling prices). Increasing the yearlt Ethanol and sugar cane productivity’s growth rate from 0.5% to 4.0% leads to a range of IRR from 17.5% to 21.5%, and of price from 0.29 US/lto0.32US/l to 0.32 US/l for first generation plant, and from 13.2% to 14.2% and of price from 0.39 US/lto0.40US/l to 0.40 US/l for second generation plant. iv) Process improvement shows little economic impact but matters on environmental side because less land is needed. Up to 10% more land can be saved compared to least advanced technology. v) Energy conversion development can improve income of the plant, especially for the first generation plant. Each 5% improvement can lead to 0.6% change in IRR project, and a reduction of 1.1% in the Minimum selling price. vi) Equipment investment is the most sensitive parameter to alter biofuel prices and profitability. The conventional plant is more sensitive to equipment investment, land prices and trash costs in this order while second generation plant is sensitive to equipment investment and almost insensitive to land prices and trash costs changes. vii) Assuming an average payment of US29.43orhigherpertonCO2debt,thesecondgenerationplantmaybecomeacompetingalternativetoconventional,firstgenerationplant.Onaverage,thetechnologycouldbepaidatreasonablecost(RevenueaverageofUS 29.43 or higher per ton CO2 debt, the second generation plant may become a competing alternative to conventional, first generation plant. On average, the technology could be paid at reasonable cost (Revenue average of US 27.7 million). viii) Productivity gains reduce the repayment time of CO2 debt, with ethanol productivity having a stronger contribution. Besides, from a growth rate of ethanol and sugar cane productivity from 0.5% to 4.0% per year, the repayment time changes from 11.8 years to a range between 6.5 years and 5.5 years and 13 and 9.5, respectively. In conclusion, the appraisal model represents a useful tool for analyzing many issues related with the dilemmas involved in biofuel production

    Redesign of technical systems

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    The paper describes a systematic approach to support the redesign process. Redesign is the adaptation of a technical system in order to meet new specifications. The approach presented is based on techniques developed in model-based diagnosis research. The essence of the approach is to find the part of the system which causes the discrepancy between a formal specification of the system to be designed and the description of the existing technical system. Furthermore, new specifications are generated, describing the new behaviour for the `faulty¬Ņ part. These specifications guide the actual design of this part. Both the specification and design description are based on YMIR, an ontology for structuring engineering design knowledge

    Pragmatisch redeneren in modelgebaseerde diagnose

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    Model-gebaseerde diagnose bepaalt de defecte componenten in een technisch systeem door middel van een gerichte reeks testen en metingen. Meetadvies wordt gegeven op basis van verkregen diagnostische hypothesen. De huidige model-gebaseerde diagnostische methoden2 hebben een hoge berekeningscomplexiteit (in 0(2")) waarbij n het aantal componenten in het model is). De Pragmatic Diagnostic Engine (POE) is een model-gebaseerde redeneermethode die een polynomiale berekeningscomplexiteit heeft (in 0(n2)). Door een beperking van het diagnostisch redeneren tot de belangrijkste diagnostische hypothesen, kan in korte tijd een goed meetadvies gegeven worden. In een aantal experimenten werd bevestigd dat PDE's meetadvies nagenoeg hetzelfde is als dat van de standaardmethode GDE

    Lactic acid production from xylose by the fungus Rhizopus oryzae

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    Lignocellulosic biomass is considered nowadays to be an economically attractive carbohydrate feedstock for large-scale fermentation of bulk chemicals such as lactic acid. The filamentous fungus Rhizopus oryzae is able to grow in mineral medium with glucose as sole carbon source and to produce optically pure l(+)-lactic acid. Less is known about the conversion by R. oryzae of pentose sugars such as xylose, which is abundantly present in lignocellulosic hydrolysates. This paper describes the conversion of xylose in synthetic media into lactic acid by ten R. oryzae strains resulting in yields between 0.41 and 0.71 g g¬Ņ1. By-products were fungal biomass, xylitol, glycerol, ethanol and carbon dioxide. The growth of R. oryzae CBS 112.07 in media with initial xylose concentrations above 40 g l¬Ņ1 showed inhibition of substrate consumption and lactic acid production rates. In case of mixed substrates, diauxic growth was observed where consumption of glucose and xylose occurred subsequently. Sugar consumption rate and lactic acid production rate were significantly higher during glucose consumption phase compared to xylose consumption phase. Available xylose (10.3 g l¬Ņ1) and glucose (19.2 g l¬Ņ1) present in a mild-temperature alkaline treated wheat straw hydrolysate was converted subsequently by R. oryzae with rates of 2.2 g glucose l¬Ņ1 h¬Ņ1 and 0.5 g xylose l¬Ņ1 h¬Ņ1. This resulted mainly into the product lactic acid (6.8 g l¬Ņ1) and ethanol (5.7 g l¬Ņ1

    Biofuel production from acid-impregnated willow and switchgrass

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    As part of a broader technical and economic feasibility study, we studied production of bioethanol from two types of lignocellulosic biomass by way of concentrated acid impregnation at low temperature. Willow chips and switchgrass were submitted to various impregnation techniques with concentrated sulfuric acid at varying acid: biomass ratios and impregnation times. Goal of the experiments was to investigate the technical feasibility of concentrated acid pretreatment technology as part of an industrial process that employs recycling of acid through biological means. Experimental results showed that significant amounts of fermentable sugars including glucose (up to 78 f max. obtainable glucose) and xylose can be obtained by relatively simple impregnation techniques at room temperature. Fermentation of willow-derived hydrolysates with S. Cerevisiae yielded 0.45 - 0.49 g ethanol/g glucose. Ethanol production rates however were 38 ower compared to standard glucose fermentation, prompting the need for further optimization to reduce the formation of acetic acid and furfural, two fermentation inhibitors. Novel impregnation techniques, including employment of sulfur trioxide, were also investigated but require more work to assess technical feasibilit

    Onderzoek naar brandveiligheid voor dieren in veestallen = Study regarding fire safety of barns for farm animals

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    Study regarding bottle necks in fire safety of barns for farm animals and possible improvements, inter alia in legislation

    Decolonizar la investigación sobre migraciones : apuntes desde una etnografía colaborativa

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    En este artículo analizamos los significados asumidos por la idea de "(in)migración(es)" y la categoría de "(in)migrante(s)" en los contextos sociales, políticos y académicos contemporáneos. Resaltando su estrecha relación con el pensamiento de Estado y la colonialidad del poder/saber, nos preguntamos por otros posibles acercamientos a la movilidad humana. Discutimos la etnografía colaborativa, entendida como una metodología decolonial que rechaza las representaciones pasivizantes hegemónicas y aspira a visibilizar los procesos de subjetivación política de las personas junto a las que se investiga. Aportando ejemplos de nuestra propia investigación colaborativa junto a Stop Desahucios-Granada 15M, ilustramos cómo la idea de (in)migración(es) y la categoría "(in)migrante(s)" se han materializado en nuestro contexto, que se encuentra definido por el activismo político y no había sido previamente alterizado como "migratorio". Concluimos resaltando la ambivalencia implícita en estas dos expresiones y reflexionamos sobre los pros y los contras implícitos en su uso.In this paper we analyze the meaning of "immigration" and "immigrant" within contemporary social, political and academic contexts. We emphasize their narrow relation with State thought and the coloniality of power/knowledge and search for alternative approaches to human mobility. With this aim, we discuss collaborative ethnography as a decolonial methodology addressed to visibilize the political subjectivation processes of the people we research with. Drawing on examples from our own collaborative research with Stop Evictions-Granada 15M, we show how the idea of "immigration" and the category "immigrants" have come into being within our field, a space of political activism which had not been previously constructed as a "migratory context". We conclude underlining the ambivalence implicit in the two aforementioned concepts and discuss the pros and cons of using them

    Paleobiology of titanosaurs: reproduction, development, histology, pneumaticity, locomotion and neuroanatomy from the South American fossil record

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    Fil: García, Rodolfo A.. Instituto de Investigación en Paleobiología y Geología. Museo Provincial Carlos Ameghino. Cipolletti; ArgentinaFil: Salgado, Leonardo. Instituto de Investigación en Paleobiología y Geología. General Roca. Río Negro; ArgentinaFil: Fernández, Mariela. Inibioma-Centro Regional Universitario Bariloche. Bariloche. Río Negro; ArgentinaFil: Cerda, Ignacio A.. Instituto de Investigación en Paleobiología y Geología. Museo Provincial Carlos Ameghino. Cipolletti; ArgentinaFil: Carabajal, Ariana Paulina. Museo Carmen Funes. Plaza Huincul. Neuquén; ArgentinaFil: Otero, Alejandro. Museo de La Plata. Universidad Nacional de La Plata; ArgentinaFil: Coria, Rodolfo A.. Instituto de Paleobiología y Geología. Universidad Nacional de Río Negro. Neuquén; ArgentinaFil: Fiorelli, Lucas E.. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica. Anillaco. La Rioja; Argentin
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