1,721,047 research outputs found
Semi-Automatic Acquisition of Visual Knowledge
No full textHeidemann G. Semi-Automatic Acquisition of Visual Knowledge. In: Geldermann J, Rommelfanger H, eds. Einsatz von Fuzzy Sets, Neuronalen Netzen und Künstlicher Intelligenz in industrieller Produktion und Umweltforschung. Fortschritt-Berichte VDI. Vol 725. Düsseldorf: VDI; 2003: 1-14
Strategic planning of a multi-product wood-biorefinery production system
No full textProducts derived from crude oil form the basis for large segments of energy and production systems. However, the availability of crude oil is limited and the combustion of fossil fuels contributes to global warming. Biorefineries can produce a product portfolio similar to that of crude-oil refineries from renewable resources and thus promote transformation towards a more sustainable bioeconomy. The actual product portfolio of a given biorefinery, however, depends on the choice and capacity of the production units used to upgrade raw materials to marketable products. Thus, to improve biorefinery product competitiveness, we apply an algorithm that combines an exact optimization algorithm nested in an Evolutionary Strategy with Geographic Information Systems to determine a wood-based biorefinery's optimal configuration, capacity, and location within the Cariboo District in Canada. The results indicate that there are numerous locations with similarly attractive economic potentials for biorefineries with 450,000 to 550,000 tons of biomass input capacity in the investigated area
Life cycle assessment of synthetic natural gas production from different CO2 sources: A cradle⇂to-gate study
Full text linkFuel production from hydrogen and carbon dioxide is considered an attractive solution as long‐term storage of electric energy and as temporary storage of carbon dioxide. A large variety of CO2 sources are suitable for Carbon Capture Utilization (CCU), and the process energy intensity depends on the separation technology and, ultimately, on the CO2 concentration in the flue gas. Since the carbon capture process emits more CO2 than the expected demand for CO2 utilization, the most sustainable CO2 sources must be selected. This work aimed at modeling a Power‐to‐Gas (PtG) plant and assessing the most suitable carbon sources from a Life Cycle Assessment (LCA) perspective. The PtG plant was supplied by electricity from a 2030 scenario for Italian electricity generation. The plant impacts were assessed using data from the ecoinvent database version 3.5, for different CO2 sources (e.g., air, cement, iron, and steel plants). A detailed discussion on how to handle multi‐functionality was also carried out. The results showed that capturing CO2 from hydrogen production plants and integrated pulp and paper mills led to the lowest impacts concerning all investigated indicators. The choice of how to handle multi‐functional activities had a crucial impact on the assessment
Life Cycle Assessment of synthetic fuel production from renewable hydrogen: Process contribution and impact assessment considering different 2030 energy mixes
No full textRenewable energy source generation has been increasing drastically for the last decades. In order to avoid grid congestions or overloads and energy curtailments, it is necessary to envisage energy storage technologies. Converting surplus electricity into hydrogen or eventually other synthetic fuels through Powerto- X technologies is regarded as a promising solution for the mid and long-term storage and for its potential of providing sector interconnection. However, synthetic fuel production consists of energy-intensive conversion steps, for which it is of importance to assess its environmental impacts before large scale plant development. This work aims at modeling and assessing the impacts of different alternative fuel synthesis based on renewable hydrogen in a life cycle assessment perspective. The analyzed fuels are chosen among the ones that can rely on a reliable and extensive infrastructure and, likewise, feed emerging and innovative technologies (e.g., fuel cells); in particular, methane, methanol, ammonia are selected as promising hydrogen carriers. The plant models developed in previous works are assessed regarding several environmental impacts in the software SimaPro. The data used in the present study included both data from ecoinvent database version 3.5, data from literature, and assumptions based on engineering practice for electricity generation, electrolysis, and concerning carbon dioxide sources. From a process contribution analysis, the sub-optimal and critical steps are pointed out and an outlook is provided. Since electricity production proved to be one of the most critical parameters, a sensitivity analysis over different 2030 energy mixes and renewable energy sources is carried out
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Optimization of sustainable seawater desalination: Modeling renewable energy integration and energy storage concepts
No full textMany arid and semi-arid regions of the world face growing freshwater scarcity, requiring increased utilization of seawater desalination to augment the existing freshwater resources. Seawater reverse osmosis (RO) is currently one of the most deployed technologies, due to its electrical energy efficiency and comparatively low costs. However, the required energy for desalination processes is often still converted from fossil sources. Given the growing demand for seawater desalination and the energy sector's parallel decarbonization, the substitution by renewable energy sources (RES) is a critical issue. The volatility, lower availability of renewable energy, and cost for required electrical energy storage (EES) are all obstacles to the decarbonization of large-scale desalination plants and may affect production volume and water production costs negatively. This paper presents a mathematical model to determine a cost-optimal energy conversion and EES mix for the design and operation of large-scale seawater RO desalination plants. The linear program ensures satisfaction of the plant's energetic demands. Furthermore, the model allows to investigate the general feasibility of integrating RES into large-scale desalination processes, which are examined by means of a case study while employing location-specific weather data. Different types of energy conversion technologies and the effect of EES on operating behavior, greenhouse gas emissions, and water unit costs are investigated. Specifically, the indirect storage of electrical energy via the smart management of a desalination plant's oversized RO membranes is examined and compared to battery energy storage (BES). Results indicate that RES cannot meet an RO desalination plant's full and constant electrical load demand without a high BES capacity, which is probably not feasible from a technical and economic point of view. The economic penalty from energy storage costs on one unit of desalinated water ranges from 3.10 /m3. However, operating an oversized RO desalination plant intermittently could reduce the energy-related costs substantially and potentially provide a more appropriate way of adapting to a volatile supply of energy from renewable sources in order to decarbonize the desalination processes. Specific emissions of desalinated water can be reduced from 1.5 kg CO2 eq./m3 when relying mostly on combined cycle gas turbines down to 0.124 kg CO2 eq./m3 by intermittent operation and fully relying on renewable energy sources
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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