2,445 research outputs found
Geology of the Eagle Ford Quadrangle, Dallas County, Texas
The Eagle Ford quadrangle includes an area of 62 square miles in western Dallas County. It is bounded by the parallels 32°45\u2700 and 32°52\u2730 N, and by the meridians 96°52\u2730 and 97°00\u2700 W. The towns of Irving and Eagle Ford are in the area, as are portions of Grand Prairie and Arcadia Park. A network of paved highways and graveled roads makes most of the quadrangle readily accessible by automobile. Physiographically, this area is part of the Black Prairie, a province of low relief in which the landscape has been largely shaped by running water. West and Elm forks of the Trinity River, with their tributaries, form a dendritic pattern over the Eagle Ford area
Host and Derivative Product Modeling and Synthesis
In recent years, numerous methods to aid designers in conceptualizing new products have been developed. These methods intend to give structure to a process that was, at one time, considered to be a purely creative exercise. Resulting from the study, implementation, and refinement of design methodologies is the notion that both the structure of the development process and the structure of the developed product are key factors in creating value in a firm’s product line. With respect to the latter key factor, product architecture, but more specifically, modular product architecture has been the subject of much study. However, prior research in the area of modular product architecture has, with limited exception, focused on the construction of modules that are to be incorporated into a product before it becomes available to its end-users; that is, the modules are incorporated ‘pre-market.’
The research contained in this thesis is focused on two tasks: advancing the notion of a modular product architecture in which modules can be incorporated into a product ‘post-market,’ and creating a method that aids designers in synthesizing these post-market modules. Researchers have examined the idea of post-market modules; however, they do not fully formalize language used to describe these modules, and they also do not give the product space created by post-market modularization well-defined boundaries. Additionally, the prior work gives no method that can be used to create post-market modules. The research presented here addresses these shortcomings in the prior work by first, defining the terms ‘derivative product’ and ‘host product’ to describe the post-market module and the product that the module augments, respectively. Second, by establishing three guidelines that are used to assess the validity of potential derivative products, giving the newly termed host and derivative product space defined boundaries. And lastly, by developing a 7-step, biomimetic-based methodology that can be used to create derivative product concepts (post-market modules). This developed methodology is applied to four case studies in which it is used to create five derivative product concepts for a given host product. Thus, 20 derivative product concepts are developed in this study, demonstrating the qualitative effectiveness of the 7-step methodology
Methanol as a fuel for internal combustion engines
Transportation of people and goods largely relies on the use of fossil hydrocarbons, contributing to global warming and problems with local air quality. There are a number of alternatives to fossil fuels that can avoid a net carbon emission and can also decrease pollutant emissions. However, many have significant difficulty in competing with fossil fuels due to either limited availability, limited energy density, high cost, or a combination of these. Methanol (CH3OH) is one of these alternatives, which was demonstrated in large fleet trials during the 1980s and 1990s, and is currently again being introduced in various places and applications. It can be produced from fossil fuels, but also from biomass and from renewable energy sources in carbon capture and utilization schemes. It can be used in pure form or as a blend component, in internal combustion engines (ICEs) or in direct methanol fuel cells (DMFCs). These features added to the fact it is a liquid fuel, making it an efficient way of storing and distributing energy, make it stand out as one of the most attractive scalable alternatives. This review focuses on the use of methanol as a pure fuel or blend component for ICEs. First, we introduce methanol historically, briefly introduce the various methods for its production, and summarize health and safety of using methanol as a fuel. Then, we focus on its use as a fuel for ICEs. The current data on the physical and chemical properties relevant for ICEs are reviewed, highlighting the differences with fuels such as ethanol and gasoline. These are then related to the research reported on the behaviour of methanol and methanol blends in spark ignition and compression ignition engines. Many of the properties of methanol that are significantly different from those of for example gasoline (such as its high heat of vaporization) lead to advantages as well as challenges. Both are extensively discussed. Methanol's performance, in terms of power output, peak and part load efficiency, and emissions formation is summarized, for so-called flex-fuel engines as well as for dedicated engines. We also briefly touch upon engine hardware changes and material compatibility. Methanol fuel reforming using engine waste heat is discussed, as a potential route towards further increases in efficiency and decreases in emissions. Next to the experimental work, research efforts into modelling the behaviour of methanol as a fuel are also reviewed, including mixture formation, normal and abnormal combustion. Methanol's properties such as high latent heat, fast burning velocity, high knock-resistance and no carbon-to-carbon bonds are shown to leverage engine technology developments such as increased compression ratios, downsizing and dilution; enabling much increased engine efficiencies. Finally, we point out the current gaps in knowledge to indicate which areas future research should be directed at
Methanol as a fuel for internal combustion engines
Transportation of people and goods largely relies on the use of fossil hydrocarbons, contributing to global warming and problems with local air quality. Thereare a number of alternatives to fossil fuels that can avoid a net carbon emission and can also decrease pollutant emissions. However, many have significant difficultyin competing with fossil fuels due to either limited availability, limited energy density, high cost, or a combination of these. Methanol (CH3OH) is one of these alternatives, which was demonstrated inlarge fleet trials during the 1980s and 1990s, and is currently again being introduced in various places and applications. It can be produced from fossil fuels,but also from biomass and from renewable energy sources in carbon capture and utilization schemes. It can be used in pure form or as a blend component, ininternal combustion engines (ICEs) or in direct methanol fuel cells (DMFCs). These features added to the fact it is a liquid fuel, making it an efficient way of storing and distributing energy, make it stand out as one of the most attractive scalable alternatives. This review focuses on the use of methanol as a pure fuel or blend componentfor ICEs. First, we introduce methanol historically, briefly introduce the various methods for its production, and summarize health and safety of using methanolas a fuel. Then, we focus on its use as a fuel for ICEs. The current data on the physical and chemical properties relevant for ICEs are reviewed, highlighting the differences with fuels such as ethanol and gasoline. These are then related to the research reported on the behaviour of methanol and methanol blendsin spark ignition and compression ignition engines. Many of the properties of methanol that are significantly different from those of for example gasoline (suchas its high heat of vaporization) lead to advantages as well as challenges. Both are extensively discussed.Methanol’s performance, in terms of power output, peak and part load efficiency, and emissions formation is summarized, for so-called flex-fuel engines as well as for dedicated engines. We also briefly touch upon engine hardware changes and material compatibility. Methanol fuel reforming using engine waste heat is discussed, as a potential route towards further increases in efficiency anddecreases in emissions. Next to the experimental work, research efforts into modelling the behaviour of methanol as a fuel are also reviewed, including mixtureformation, normal and abnormal combustion. Methanol’s properties such as high latent heat, fast burning velocity, high knock-resistance and no carbonto-carbonbonds are shown to leverage engine technology developments such as increased compression ratios, downsizing and dilution; enabling much increasedengine efficiencies. Finally, we point out the current gaps in knowledge to indicate which areas future research should be directed at
Assessment of Noise Reduction Concepts for Leading-Edge Slat Noise
The leading-edge slat of a high-lift airfoil can be a significant noise contributor during aircraft landing. This paper summarizes the effects of several passive noise reduction devices on the 30P30N high-lift airfoil. Experiments are conducted on a two-dimensional multi-element high-lift airfoil with leading-edge slat extensions, gap filler, and cove filler in an anechoic wind tunnel to evaluate the effect of passive flow control on the acoustics generated by the unsteady flow field. Slat geometry modifications associated with the treatments alter the flow field in the region that dominates the generation of the acoustic field. Three angles of attack (a(k) = 8, 10, and 15.5) and three different Reynolds numbers (Re(c) = 1.2e6, 1.5e6, and 1.71e6) are selected as the test conditions. Steady surface pressure measurements are conducted to assess the effect of the treatments on the lift and drag. Unsteady surface pressure measurements along with the far-field acoustic array measurements are performed to evaluate the changes in near- and far-field pressure fluctuations, respectively. Delay and Sum (DAS) beamforming method is applied to locate the noise sources on the model and provide integrated spectra. Implementation difficulties with the gap filler led to structural integration deficiencies that prevented a fair assessment of this technology. Among the other passive devices, the cove filler s the most effective noise reduction, along with a negligible change in the aerodynamic metrics
Perceptions of the intergroup structure and anti-Asian prejudice amongst white Australians
Proof oSubjective intergroup beliefs and authoritarianism were assessed in a field study (N= 255) of White Australians’ anti-Asian stereotyping and prejudice. A social identity analysis of intergroup prejudice was adopted, such that perceptions of the intergroup structure (instability, permeability, legitimacy and higher ingroup status) were proposed as predictors of higher prejudice (blatant and covert) and less favorable stereotyping. Consistent with the social identity approach, both independent and interacting roles for sociostructural predictors of Anti-Asian bias were observed, even after demographic and personality variables were controlled. For example, perceived legitimacy was associated with higher prejudice when White Australians’ status position relative to Asian Australians was valued. Moreover, when participants evaluated Whites’ position as unstable and high status or legitimate, perceptions of permeable intergroup boundaries were associated with anti-Asian bias. The present findings demonstrate status protection responses in advantaged group members in a field setting, lending weight to the contention that perceptions of sociostructural threat interact to predict outgroup derogation. Implications for theories of intergroup relations are discussed
High-intensity exercise in the evening does not disrupt sleep in endurance runners.
PURPOSE: To investigate the effect of early evening exercise training at different intensities on nocturnal sleep and cardiac autonomic activity in endurance-trained runners. METHODS: Eight runners completed three experimental trials in a randomised, counterbalanced order. In the early evening (end of exercise 3.5 h before bedtime), participants performed either: (i) a 1 h high-intensity interval running session (HIGH, 6 × 5 min at 90% VO2peak interspersed with 5 min recovery); (ii) a 1 h low-intensity running session (LOW, 60 min at 45% VO2peak) or (iii) no exercise (CON). Subsequent nocturnal sleep was assessed using polysomnography, wristwatch actigraphy, and subjective sleep quality. A two-lead electrocardiogram recorded nocturnal cardiac autonomic activity. RESULTS: Total sleep time increased after HIGH (477.4 ± 17.7 min, p = 0.022) and LOW (479.6 ± 15.6 min, p = 0.006) compared with CON (462.9 ± 19.0 min). Time awake was lower after HIGH (31.8 ± 18.5 min, p = 0.047) and LOW (30.4 ± 15.7 min, p = 0.008) compared with CON (46.6 ± 20.0 min). There were no differences between conditions for actigraphy and subjective sleep quality (p > 0.05). Nocturnal heart rate variability was not different between conditions, but average nocturnal heart rate increased after HIGH (50 ± 5 beats min-1) compared with LOW (47 ± 5 beats min-1, p = 0.02) and CON (47 ± 5 beats min-1, p = 0.028). CONCLUSION: When performed in the early evening, high-intensity exercise does not disrupt and may even improve subsequent nocturnal sleep in endurance-trained runners, despite increased cardiac autonomic activity. Additionally, low-intensity exercise induced positive changes in sleep behaviour that are comparable to those obtained following high-intensity exercise
Stem, root, and older leaf N:P ratios are more responsive indicators of soil nutrient availability than new foliage
Author Posting. © Ecological Society of America, 2014. This article is posted here by permission of Ecological Society of America for personal use, not for redistribution. The definitive version was published in Ecology 95 (2014): 2062–2068, doi:10.1890/13-1671.1.Foliar nitrogen to phosphorus (N:P) ratios are widely used to indicate soil nutrient availability and limitation, but the foliar ratios of woody plants have proven more complicated to interpret than ratios from whole biomass of herbaceous species. This may be related to tissues in woody species acting as nutrient reservoirs during active growth, allowing maintenance of optimal N:P ratios in recently produced, fully expanded leaves (i.e., “new” leaves, the most commonly sampled tissue). Here we address the hypothesis that N:P ratios of newly expanded leaves are less sensitive indicators of soil nutrient availability than are other tissue types in woody plants. Seedlings of five naturally established tree species were harvested from plots receiving two years of fertilizer treatments in a lowland tropical forest in the Republic of Panama. Nutrient concentrations were determined in new leaves, old leaves, stems, and roots. For stems and roots, N:P ratios increased after N addition and decreased after P addition, and trends were consistent across all five species. Older leaves also showed strong responses to N and P addition, and trends were consistent for four of five species. In comparison, overall N:P ratio responses in new leaves were more variable across species. These results indicate that the N:P ratios of stems, roots, and older leaves are more responsive indicators of soil nutrient availability than are those of new leaves. Testing the generality of this result could improve the use of tissue nutrient ratios as indices of soil nutrient availability in woody plants.Data are from Santiago et al. (2012), which was supported by
a grant from the Andrew W. Mellon Foundation to S. J.
Wright, a Smithsonian Institute Scholarly Studies grant to S. J.
Wright and J. B. Yavitt, and a University of California
Regent’s Faculty Fellowship to L. S. Santiago. L. A.
Schreeg was partially supported through a Marine Biological
Laboratory-Brown University SEED grant to Z. Cardon, S.
Porder, and L. A. Schreeg
Host and Derivative Product Modeling and Synthesis
In recent years, numerous methods to aid designers in conceptualizing new products have been developed. These methods intend to give structure to a process that was, at one time, considered to be a purely creative exercise. Resulting from the study, implementation, and refinement of design methodologies is the notion that both the structure of the development process and the structure of the developed product are key factors in creating value in a firm’s product line. With respect to the latter key factor, product architecture, but more specifically, modular product architecture has been the subject of much study. However, prior research in the area of modular product architecture has, with limited exception, focused on the construction of modules that are to be incorporated into a product before it becomes available to its end-users; that is, the modules are incorporated ‘pre-market.’
The research contained in this thesis is focused on two tasks: advancing the notion of a modular product architecture in which modules can be incorporated into a product ‘post-market,’ and creating a method that aids designers in synthesizing these post-market modules. Researchers have examined the idea of post-market modules; however, they do not fully formalize language used to describe these modules, and they also do not give the product space created by post-market modularization well-defined boundaries. Additionally, the prior work gives no method that can be used to create post-market modules. The research presented here addresses these shortcomings in the prior work by first, defining the terms ‘derivative product’ and ‘host product’ to describe the post-market module and the product that the module augments, respectively. Second, by establishing three guidelines that are used to assess the validity of potential derivative products, giving the newly termed host and derivative product space defined boundaries. And lastly, by developing a 7-step, biomimetic-based methodology that can be used to create derivative product concepts (post-market modules). This developed methodology is applied to four case studies in which it is used to create five derivative product concepts for a given host product. Thus, 20 derivative product concepts are developed in this study, demonstrating the qualitative effectiveness of the 7-step methodology
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