34,986 research outputs found

    Towards transportation fuels via hydrothermal liquefaction of biowaste

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    This study explores techniques to enhance the production and quality of hydrothermal liquefaction (HTL) biocrude oil and aims to make it more amenable for conversion into transportation fuel. This area of research is becoming increasingly important because the establishment of a sustainable energy supply addresses national and energy security concerns. Furthermore, jet fuel is of particular importance because the U.S. Department of Energy asserts that the current global commercial jet fuel market (106 billion gallons) is projected to grow rapidly by the year 2050 (230 billion gallons). Unlike light-duty vehicles (cars, trucks, etc.) which can use low energy density fuel and batteries, airplanes will be likely constrained to using high energy density jet fuel. Airlines have committed to carbon-neutral growth starting in 2021. Thus, establishing cost-competitive and environmentally sustainable aviation fuel (SAF) has been recognized as essential to achieving carbon neutrality. This study incorporates chemical, biological, and physical techniques to augment the quality of HTL biocrude oil from biowaste and make it amenable for upgrading into transportation fuel. First, the extraction agent’s impact on the HTL product yield, characteristics, and energy efficiency was evaluated. Three representative extraction solvents (acetone, dichloromethane, and toluene) were chosen with three representative high-carbohydrate, high-protein, and high-ash content HTL feedstocks (Chlorella sp., Nannochloropsis sp., and Enteromorpha pr., respectively). Among the three solvents, dichloromethane exhibited the highest biocrude oil yield (dry biomass), net energy values, and fossil energy ratio values amongst all feedstocks. The solvent polarity, chemical structure, hydrogen bonding, and dipole-dipole interactions all could influence the HTL biocrude extraction (quantity and properties). Extraction solvent selection should be carefully considered and normalized for the reporting of HTL yields and energy recoveries. Second, a novel integrated process of biological (dark fermentation) and thermochemical (HTL) processes herein named DF-HTL, was investigated to enhance the yield and quality of HTL biocrude oil. Compared with the control, DF-HTL significantly enhanced the biocrude oil yield (wt.%), carbon content (mol), energy content (MJ), and energy conversion ratio by 9.8%, 29.7%, 40.0%, and 61.0%, respectively. Furthermore, this process decreased the aqueous by-product yield (wt.%), carbon content (mol), nitrogen content (mol), and ammonia content (mol) by 19.0%, 38.4%, 25.0%, and 13.2%, respectively. On the other hand, DF-HTL also augmented the nitrogen content (mol) of the biocrude oil by 42.2% in comparison to the control. The benefits of DF-HTL were attributed to the increased acid content, the incorporation of H2 as a processing gas, and the enhancement of the Maillard reaction which shifted the distribution of the HTL products from the aqueous phase to the biocrude oil phase. Third, fractional distillation was conducted to explore how physical separation of chemical compounds from biocrude oil could improve the biocrude oil properties, including the chemical (heteroatom content, energy content), physical (viscosity, density), and thermal (boiling point distribution, cetane value, cold-flow properties) properties. Distillates from HTL biocrude oil derived from food waste demonstrated increased H:C (4.2-13.7%) and HHV (4.1-21.3%) values. Furthermore, distillation decreased O:C (5.5-93.5%) and N:C (6.0-39.0%) values compared to the biocrude oil, leading to values similar to those of gasoline, diesel, and Jet A fuels. With respect to the physical properties, distillation decreased the density (23.8-30.5%) and viscosity (99.5-99.9%), while the acidity either increased or decreased depending on the distillation temperature range. Despite the benefits of distillation, blending was still required due to the poor N:C, viscosity, and acidity of the distillates. Finally, the stability of biocrude oil distillates derived from food waste was investigated in two distillation temperature ranges: low-temperature (199-238°C) and medium temperature (238-274°C) distillates. A stability study was conducted to understand the influence of storage conditions (headspace and temperature) on the distillate properties. Results demonstrated that the most positively impacted characteristics of the low-temperature distillates were the vacuum oil fraction (578.4-1,172.4%), distribution of compounds < 300 Da (633.3-780.0%), and the diesel fraction (542.6-765.3%). As for the medium-temperature distillates, the vacuum oil fraction (3,209.9-3,632.8%), distribution of compounds < 300 Da (580.8-741.0%), and the unsaturated hydrocarbons (48.5-75.4%) were the most positively impacted parameters. Comparing the treatment conditions, the storage temperature and headspace elicited different effects depending on the oil distillation range. Storage also decreased the O:C (21.6% and 86.5%), N:C (32.0% and 26.1%), and increased the HHV (3.1% and 10.8%) values in the low- and medium-temperature distillates, respectively. Furthermore, only slight deviations were observed in the density (5.2% and 7.4%) and viscosity (5.2% and 0.8%), respectively.LimitedAuthor requested closed access (OA after 2yrs) in Vireo ETD syste

    Serving to secure "Global Korea": Gender, mobility, and flight attendant labor migrants

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    This dissertation is an ethnography of mobility and modernity in contemporary South Korea (the Republic of Korea) following neoliberal restructuring precipitated by the Asian Financial Crisis (1997). It focuses on how comparative “service,” “security,” and “safety” fashioned “Global Korea”: an ongoing state-sponsored project aimed at promoting the economic, political, and cultural maturation of South Korea from a once notoriously inhospitable, “backward” country (hujin’guk) to a now welcoming, “advanced country” (sŏnjin’guk). Through physical embodiments of the culturally-specific idiom of “superior” service (sŏbisŭ), I argue that aspiring, current, and former Korean flight attendants have driven the production and maintenance of this national project. More broadly, as a driver of this national project, this occupation has emerged out of the country’s own aspirational flights from an earlier history of authoritarian rule, labor violence, and xenophobia. Against the backdrop of the Korean state’s aggressive neoliberal restructuring, globalization efforts, and current “Hell Chosun” (Helchosŏn) economy, a group of largely academically and/or class disadvantaged young women have been able secure individualized modes of pleasure, self-fulfillment, and class advancement via what I deem “service mobilities.” Service mobilities refers to the participation of mostly women in a traditionally devalued but growing sector of the global labor market, the “pink collar” economy centered around “feminine” care labor. Korean female flight attendants share labor skills resembling those of other foreign labor migrants (chiefly from the “Global South”), who perform care work deemed less desirable. Yet, Korean female flight attendants elude the stigmatizing, classed, and racialized category of “labor migrant.” Moreover, within the context of South Korea’s unique history of rapid modernization, the flight attendant occupation also commands considerable social prestige. Based on ethnographic and archival research on aspiring, current, and former Korean flight attendants, this dissertation asks how these unique care laborers negotiate a metaphorical and literal series of sustained border crossings and inspections between Korean flight attendants’ contingent status as lowly care-laboring migrants, on the one hand, and ostensibly glamorous, globetrotting elites, on the other. This study contends the following: first, the flight attendant occupation in South Korea represents new politics of pleasure and pain in contemporary East Asia. Second, Korean female flight attendants’ enactments of soft, sanitized, and glamorous (hwaryŏhada) service help to purify South Korea’s less savory past. In so doing, Korean flight attendants reconstitute the historical role of female laborers as burden bearers and caretakers of the Korean state.U of I OnlyAuthor submitted a 2-year U of I restriction extension request

    A snapshot of Central Bank (two year) forecasting: a mixed picture

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    Central Banks normally adjust monetary policy so that inflation hits the Inflation Target (IT) within two years. Since a central bank must believe its policy stance is appropriate to achieve this goal, its inflation forecast at the two-year horizon should generally be close to target. We examine whether this has held for three main Central Banks, Bank of England, ECB and Fed. During the IT period, there have been two crisis periods, The Great Financial Crisis (GFC), and then Covid/Ukraine. We examine how the two-year forecasts differed depending on whether we were in a crisis, or more normal, period. Although over the whole IT period, up until 2022, both forecasts and outcomes were commendably close to target, we found that this was due to a sizeable forecast underestimate of the effects of policy and inherent resilience to revive inflation after each crisis hit, largely offset by an overestimate of the effect of monetary policy to restore inflation to target during more normal times. We attribute such latter overestimation to an unwarranted belief in forward looking, ‘well anchored’, expectations amongst households and firms, and to a failure to recognise the underlying disinflationary trends, especially in 2010-2019. We outline a novel means for assessing whether these latter trends were primarily demand driven, e.g. secular stagnation, or supply shocks, a labour supply surge. Finally, we examine how forecasts for the uncertainty of outcomes and relative risk (skew) to the central forecast have developed by examining the Bank of England’s fan chart, again at the two-year horizon

    Patching Weak Convolutional Neural Network Models through Modularization and Composition

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    Despite great success in many applications, deep neural networks are not always robust in practice. For instance, a convolutional neuron network (CNN) model for classification tasks often performs unsatisfactorily in classifying some particular classes of objects. In this work, we are concerned with patching the weak part of a CNN model instead of improving it through the costly retraining of the entire model. Inspired by the fundamental concepts of modularization and composition in software engineering, we propose a compressed modularization approach, CNNSplitter, which decomposes a strong CNN model for NN-class classification into NN smaller CNN modules. Each module is a sub-model containing a part of the convolution kernels of the strong model. To patch a weak CNN model that performs unsatisfactorily on a target class (TC), we compose the weak CNN model with the corresponding module obtained from a strong CNN model. The ability of the weak CNN model to recognize the TC can thus be improved through patching. Moreover, the ability to recognize non-TCs is also improved, as the samples misclassified as TC could be classified as non-TCs correctly. Experimental results with two representative CNNs on three widely-used datasets show that the averaged improvement on the TC in terms of precision and recall are 12.54% and 2.14%, respectively. Moreover, patching improves the accuracy of non-TCs by 1.18%. The results demonstrate that CNNSplitter can patch a weak CNN model through modularization and composition, thus providing a new solution for developing robust CNN models.Comment: Accepted at ASE'2

    Indoor climate quality assessment in civil aircraft cabins: A field study

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    Indoor Climate Quality is the way to assess how much thermal and indoor air quality conditions might influence people's comfort indoors. Passengers traveling on commercial airplanes are increasingly demanding comfort inside the cabin. So, creating a comfortable environment is a relevant requirement to be considered. Although indoor climate standards cover mainly buildings, other indoor environments may use the same concepts. This study aimed to present a multiprobe device for indoor climate quality assessment and a methodology to cate-gorize thermal comfort and indoor air quality levels in twenty-five flights between 2019 and the beginning of 2020. Data were collected in two distinct seasons, Heating and Cooling, regarding the mode of use of HVAC systems, depending on the predominant passengers' clothing set, for different aircraft types and routes. It was analyzed how much thermal comfort and indoor air quality parameters are in accordance with the categories established in the EN 16798-1 standard. As the main findings, it can be concluded that the environmental pa-rameters analyzed on flights were mostly within the comfort range. However, there is a possibility of improvement in thermal comfort since the predominance of values in the best comfort category is still marginal, focusing on the study of air cleaning and air distribution flow to improve people's comfort and energy saving.info:eu-repo/semantics/publishedVersio

    Interval Type-2 Beta Fuzzy Near Sets Approach to Content-Based Image Retrieval

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    In computer-based search systems, similarity plays a key role in replicating the human search process. Indeed, the human search process underlies many natural abilities such as image recovery, language comprehension, decision making, or pattern recognition. The search for images consists of establishing a correspondence between the available image and that sought by the user, by measuring the similarity between the images. Image search by content is generaly based on the similarity of the visual characteristics of the images. The distance function used to evaluate the similarity between images depends notonly on the criteria of the search but also on the representation of the characteristics of the image. This is the main idea of a content-based image retrieval (CBIR) system. In this article, first, we constructed type-2 beta fuzzy membership of descriptor vectors to help manage inaccuracy and uncertainty of characteristics extracted the feature of images. Subsequently, the retrieved images are ranked according to the novel similarity measure, noted type-2 fuzzy nearness measure (IT2FNM). By analogy to Type-2 Fuzzy Logic and motivated by near sets theory, we advanced a new fuzzy similarity measure (FSM) noted interval type-2 fuzzy nearness measure (IT-2 FNM). Then, we proposed three new IT-2 FSMs and we have provided mathematical justification to demonstrate that the proposed FSMs satisfy proximity properties (i.e. reflexivity, transitivity, symmetry, and overlapping). Experimental results generated using three image databases showing consistent and significant results

    Strategies for Early Learners

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    Welcome to learning about how to effectively plan curriculum for young children. This textbook will address: • Developing curriculum through the planning cycle • Theories that inform what we know about how children learn and the best ways for teachers to support learning • The three components of developmentally appropriate practice • Importance and value of play and intentional teaching • Different models of curriculum • Process of lesson planning (documenting planned experiences for children) • Physical, temporal, and social environments that set the stage for children’s learning • Appropriate guidance techniques to support children’s behaviors as the self-regulation abilities mature. • Planning for preschool-aged children in specific domains including o Physical development o Language and literacy o Math o Science o Creative (the visual and performing arts) o Diversity (social science and history) o Health and safety • Making children’s learning visible through documentation and assessmenthttps://scholar.utc.edu/open-textbooks/1001/thumbnail.jp

    Intensification or Diversification: Responses by Anti Health-Pass Entrepreneurs to French Government Announcements

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    We study the extent to which French entrepreneurs mobilized in an online collective action against the generalization of the health-pass policy in summer 2021. We document the dynamics of registrations on the website Animap.fr where entrepreneurs could claim they would not check the health-pass of their clients. We first note an over-representation of complementary and alternative medicine (CAM) practitioners among the mobilized people. We also suggest that professionals related to the touristic industry mobilized on the website. Second, we show that the government announcements led to an increase in the mobilization. However, they did not affect the diversity of the entrepreneurs joining the action. This lack of diversity may have restricted the pool of potential participants as well as limited the identification of the “public opinion” to the mobilization
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