940 resultados para Oil. External constraint. Development
Resumo:
A range of societal issues have been caused by fossil fuel consumption in the transportation sector in the United States (U.S.), including health related air pollution, climate change, the dependence on imported oil, and other oil related national security concerns. Biofuels production from various lignocellulosic biomass types such as wood, forest residues, and agriculture residues have the potential to replace a substantial portion of the total fossil fuel consumption. This research focuses on locating biofuel facilities and designing the biofuel supply chain to minimize the overall cost. For this purpose an integrated methodology was proposed by combining the GIS technology with simulation and optimization modeling methods. The GIS based methodology was used as a precursor for selecting biofuel facility locations by employing a series of decision factors. The resulted candidate sites for biofuel production served as inputs for simulation and optimization modeling. As a precursor to simulation or optimization modeling, the GIS-based methodology was used to preselect potential biofuel facility locations for biofuel production from forest biomass. Candidate locations were selected based on a set of evaluation criteria, including: county boundaries, a railroad transportation network, a state/federal road transportation network, water body (rivers, lakes, etc.) dispersion, city and village dispersion, a population census, biomass production, and no co-location with co-fired power plants. The simulation and optimization models were built around key supply activities including biomass harvesting/forwarding, transportation and storage. The built onsite storage served for spring breakup period where road restrictions were in place and truck transportation on certain roads was limited. Both models were evaluated using multiple performance indicators, including cost (consisting of the delivered feedstock cost, and inventory holding cost), energy consumption, and GHG emissions. The impact of energy consumption and GHG emissions were expressed in monetary terms to keep consistent with cost. Compared with the optimization model, the simulation model represents a more dynamic look at a 20-year operation by considering the impacts associated with building inventory at the biorefinery to address the limited availability of biomass feedstock during the spring breakup period. The number of trucks required per day was estimated and the inventory level all year around was tracked. Through the exchange of information across different procedures (harvesting, transportation, and biomass feedstock processing procedures), a smooth flow of biomass from harvesting areas to a biofuel facility was implemented. The optimization model was developed to address issues related to locating multiple biofuel facilities simultaneously. The size of the potential biofuel facility is set up with an upper bound of 50 MGY and a lower bound of 30 MGY. The optimization model is a static, Mathematical Programming Language (MPL)-based application which allows for sensitivity analysis by changing inputs to evaluate different scenarios. It was found that annual biofuel demand and biomass availability impacts the optimal results of biofuel facility locations and sizes.
Resumo:
An electrospray source has been developed using a novel new fluid that is both magnetic and conductive. Unlike conventional electrospray sources that required microfabricated structures to support the fluid to be electrosprayed, this new electrospray fluid utilizes the Rosensweig instability to create the structures in the magnetic fluid when an external magnetic field was applied. Application of an external electric field caused these magnetic fluid structures to spray. These fluid based structures were found to spray at a lower onset voltage than was predicted for electrospray sources with solid structures of similar geometry. These fluid based structures were also found to be resilient to damage, unlike the solid structures found in traditional electrospray sources. Further, experimental studies of magnetic fluids in non-uniform magnetic fields were conducted. The modes of Rosensweig instabilities have been studied in-depth when created by uniform magnetic fields, but little to no studies have been performed on Rosensweig instabilities formed due to non-uniform magnetic fields. The measured spacing of the cone-like structures of ferrofluid, in a non-uniform magnetic field, were found to agree with a proposed theoretical model.
Resumo:
This honors thesis research project was the study and development of a compact separation device for the oil and gas industry involving a multiphase cylindrical screen filter. Cylindrical screens can be used for solids removal in multiphase flow in upstream oil and gas applications. This study focused on cylindrical wire-wrap screen test unit design and performance characterization to determine volumetric flow rate and pressure drop correlations. The project goals were met with research, test unit design, CFD modeling, calculations, and physical testing. The comprehensive testing will take place during the summer of 2013 and is planned to consist of building the designed flowloop and housing and using high capacity pumps to achieve higher flow rates. Multiphase testing will be performed with water, air, and sand particles and flow and pressure effects will be evaluated for solids filtering over time.
Resumo:
This presentation describes research at Montana Tech to improve oil recovery rates in the Elm Coulee Oil Field in the Bakken Reservoir, Richmond County, Montana. The slides display current recovery rate predictions, enhanced oil recovery methods, reservoir model building and history matching strategies. Recommended development strategies include implementing hydrocarbon gas injection operations to improve current oil recovery rates by more than 75%. The impact of increased production on Production Engineers is also described. The Principal Investigators include John Evans, Leo Heath, David Reichhardt and Burt Todd in the Petroleum Engineering Department.
Resumo:
BACKGROUND: Heavier than water tamponades offer the possibility to support the inferior part of the fundus after retinal detachment. The aim of this study was to evaluate the anatomic and functional outcome of complicated retinal detachment treated with vitreous surgery and heavy silicone oil (HSO) tamponade. Surgery was performed in eyes with rhegmatogenous retinal detachment (RD) predominantly in the lower hemisphere or with penetrating injury (either as primary intervention or after development of proliferative vitreoretinopathy [PVR]). MATERIALS AND METHODS: Sixty-one eyes of 61 patients with RD - mostly complicated by PVR - and a minimum follow-up of 12 months were included in this study. Vitreoretinal surgery with HSO (Oxane HD) tamponade was performed in all patients. In 52 patients, heavy silicone oil was used in the management of complicated RD. 9 patients had surgery for complicated RD after penetrating eye injury.The mean follow-up period was 30.3 +/- 10.2 months. RESULTS: The overall final anatomic success rate was 79 %. In 39 % of the cases the retina remained attached during the entire follow-up period. CONCLUSIONS: The anatomic success rate after surgery with HSO (Oxane HD) was relatively low; however, only complex cases bearing a higher risk of retinal re-detachment received HSO in this study. Oxane HD does not appear to have major advantages compared to conventional silicone oil or other new-generation heavy silicone oils in these cases.
Resumo:
The present study analyses transdisciplinary co-production of knowledge in the development of organic farming in Switzerland by using Fleck's theory of thought styles and thought collectives. Three different phases can be identified throughout the historical development. The initial phase lasting from the beginning of the 1920s to the early 1970s contains numerous characteristics of diverse well-established definitions and concepts of transdisciplinarity and represents a successful transdisciplinary process, which has not been perceived as such in the past and present scientific discussion. The second and third phases show an increasing segregation of thought collectives, caused by internal changes such as the establishment of specialised research institutions and external processes like agriculture policy and market development. These developments led to a decreasing degree of transdisciplinarity. We observe an ambiguous trend: the continuously growing and today well-established positive societal recognition of an initially rather little accepted newcomer movement is associated with the gradual loss of its very valuable forms of knowledge co-production and the related philosophical background. In order to maintain the various forms of transdisciplinary co-production of knowledge, one has to reflect not only their results or outcome but also the whole cooperation process, which has led to these results. The understanding of the historical development and characteristic features of knowledge co-production as presented in this study will help to reinforce transdisciplinary research in organic agriculture and research on transdisciplinarity in general.
Resumo:
The goal of this article was to study teachers' professional development related to web-based learning in the context of the teacher community. The object was to learn in what kind of networks teachers share the knowledge of web-based learning and what are the factors in the community that support or challenge teachers professional development of web-based learning. The findings of the study revealed that there are teachers who are especially active, called the central actors in this study, in the teacher community who collaborate and share knowledge of web-based learning. These central actors share both technical and pedagogical knowledge of web-based learning in networks that include both internal and external relations in the community and involve people, artefacts and a variety of media. Furthermore, the central actors appear to bridge different fields of teaching expertise in their community. According to the central actors' experiences the important factors that support teachers' professional development of web-based learning in the community are; the possibility to learn from colleagues and from everyday working practices, an emotionally safe atmosphere, the leader's personal support and community-level commitment. Also, the flexibility in work planning, challenging pupils, shared lessons with colleagues, training events in an authentic work environment and colleagues' professionalism are considered meaningful for professional development. As challenges, the knowledge sharing of web-based learning in the community needs mutual interests, transactive memory, time and facilities, peer support, a safe atmosphere and meaningful pedagogical practices. On the basis of the findings of the study it is suggested that by intensive collaboration related to web-based learning it may be possible to break the boundaries of individual teachership and create such sociocultural activities which support collaborative professional development in the teacher community. Teachers' in-service training programs should be more sensitive to the culture of teacher communities and teachers' reciprocal relations. Further, teacher trainers should design teachers' in-service training of web-based learning in co-evolution with supporting networks which include the media and artefacts as well as people.
Resumo:
The goal of this article was to study teachers' professional development related to web-based learning in the context of the teacher community. The object was to learn in what kind of networks teachers share the knowledge of web-based learning and what are the factors in the community that support or challenge teachers professional development of web-based learning. The findings of the study revealed that there are teachers who are especially active, called the central actors in this study, in the teacher community who collaborate and share knowledge of web-based learning. These central actors share both technical and pedagogical knowledge of web-based learning in networks that include both internal and external relations in the community and involve people, artefacts and a variety of media. Furthermore, the central actors appear to bridge different fields of teaching expertise in their community. According to the central actors' experiences the important factors that support teachers' professional development of web-based learning in the community are; the possibility to learn from colleagues and from everyday working practices, an emotionally safe atmosphere, the leader's personal support and community-level commitment. Also, the flexibility in work planning, challenging pupils, shared lessons with colleagues, training events in an authentic work environment and colleagues' professionalism are considered meaningful for professional development. As challenges, the knowledge sharing of web-based learning in the community needs mutual interests, transactive memory, time and facilities, peer support, a safe atmosphere and meaningful pedagogical practices. On the basis of the findings of the study it is suggested that by intensive collaboration related to web-based learning it may be possible to break the boundaries of individual teachership and create such sociocultural activities which support collaborative professional development in the teacher community. Teachers' in-service training programs should be more sensitive to the culture of teacher communities and teachers' reciprocal relations. Further, teacher trainers should design teachers' in-service training of web-based learning in co-evolution with supporting networks which include the media and artefacts as well as people.
Resumo:
The goal of this article was to study teachers' professional development related to web-based learning in the context of the teacher community. The object was to learn in what kind of networks teachers share the knowledge of web-based learning and what are the factors in the community that support or challenge teachers professional development of web-based learning. The findings of the study revealed that there are teachers who are especially active, called the central actors in this study, in the teacher community who collaborate and share knowledge of web-based learning. These central actors share both technical and pedagogical knowledge of web-based learning in networks that include both internal and external relations in the community and involve people, artefacts and a variety of media. Furthermore, the central actors appear to bridge different fields of teaching expertise in their community. According to the central actors' experiences the important factors that support teachers' professional development of web-based learning in the community are; the possibility to learn from colleagues and from everyday working practices, an emotionally safe atmosphere, the leader's personal support and community-level commitment. Also, the flexibility in work planning, challenging pupils, shared lessons with colleagues, training events in an authentic work environment and colleagues' professionalism are considered meaningful for professional development. As challenges, the knowledge sharing of web-based learning in the community needs mutual interests, transactive memory, time and facilities, peer support, a safe atmosphere and meaningful pedagogical practices. On the basis of the findings of the study it is suggested that by intensive collaboration related to web-based learning it may be possible to break the boundaries of individual teachership and create such sociocultural activities which support collaborative professional development in the teacher community. Teachers' in-service training programs should be more sensitive to the culture of teacher communities and teachers' reciprocal relations. Further, teacher trainers should design teachers' in-service training of web-based learning in co-evolution with supporting networks which include the media and artefacts as well as people.
Resumo:
Lake-effect snow is an important constraint on ecological and socio-economic systems near the North American Great Lakes. Little is known about the Holocene history of lake-effect snowbelts, and it is difficult to decipher how lake-effect snowfall abundance affected ecosystem development. We conducted oxygen-isotope analysis of calcite in lake-sediment cores from northern Lower Michigan to infer Holocene climatic variation and assess snowbelt development. The two lakes experience the same synoptic-scale climatic systems, but only one of them (Huffman Lake) receives a significant amount of lake-effect snow. A 177-cm difference in annual snowfall causes groundwater inflow at Huffman Lake to be 18O-depleted by 2.3‰ relative to O'Brien Lake. To assess when the lake-effect snowbelt became established, we compared calcite-δ18O profiles of the last 11,500 years from these two sites. The chronologies are based on accelerator-mass-spectrometry 14C ages of 11 and 17 terrestrial-plant samples from Huffman and O'Brien lakes, respectively. The values of δ18O are low at both sites from 11,500 to 9500 cal yr BP when the Laurentide Ice Sheet (LIS) exerted a dominant control over the regional climate and provided periodic pulses of meltwater to the Great Lakes basin. Carbonate δ18O increases by 2.6‰ at O'Brien Lake and by 1.4‰ at Huffman Lake between 9500 and 7000 cal yr BP, suggesting a regional decline in the proportion of runoff derived from winter precipitation. The Great Lakes snowbelt probably developed between 9500 and 5500 cal yr BP as inferred from the progressive 18O-depletion at Huffman Lake relative to O'Brien Lake, with the largest increase of lake-effect snow around 7000 cal yr BP. Lake-effect snow became possible at this time because of increasing contact between the Great Lakes and frigid arctic air. These changes resulted from enhanced westerly flow over the Great Lakes as the LIS collapsed, and from rapidly rising Great Lakes levels during the Nipissing Transgression. The δ18O difference between Huffman and O'Brien lakes declines after 5500 cal yr BP, probably because of a northward shift of the polar vortex that brought increasing winter precipitation to the entire region. However, δ18O remains depleted at Huffman Lake relative to O'Brien Lake because of the continued production of lake-effect snow.
Resumo:
Objective: Cognitive problems and biases play an important role in the development and continuation of psychosis. A self-report measure of these deficits and processes was developed (Davos Assessment of Cognitive Biases Scale: DACOBS) and is evaluated in this study. Methods: An item pool made by international experts was used to develop a self-report scale on a sample of 138 schizophrenia spectrum patients. Another sample of 71 patients was recruited to validate the subscales. A group of 186 normal control subjects was recruited to establish norms and examine discriminative validity. Results: Factor analyses resulted in seven factors, each with six items (jumping to conclusions, belief inflexibility bias, attention for threat bias, external attribution bias, social cognition problems, subjective cognitive problems and safety behavior). All factors independently explained the variance (eigenvalues > 2) and total explained variance was 45%. Reliability was good (Cronbach's alpha = .90; split-half reliability = .92; test–retest reliability = .86). The DACOBS discriminates between schizophrenia spectrum patients and normal control subjects. Validity was affirmed for five of seven subscales. The scale ‘Subjective Cognitive problems’ was not associated with objective cognitive functioning and ‘Social cognition problems’ was not associated with the Hinting task, but with the scale measuring ideas of social reference. Conclusions: The DACOBS scale, with seven independent subscales, is reliable and valid for use in clinical practice and research.
Resumo:
Access to affordable and renewable sources of energy is crucial to reducing poverty and enhancing rural development in countries of the global South. Straight vegetable oil was recently identified as a possible alternative to conventional biomass for rural energy supply. In this context, the Jatropha curcas Linn. species has been extensively investigated with regard to its potential as a biofuel feedstock. In contrast, only little is known about Jatropha mahafalensis Jum. & H. Perrier, which is an indigenous and endemic representative of the Jatropha genus in Madagascar. This paper explores the potential and suitability of J. mahafalensis as a biofuel feedstock. Seed samples were collected in the area of Soalara in south-western Madagascar in February and September 2011. Two agro-ecological zones (coastal area and calcareous plateau) and two plant age groups (below and above 10 years) were considered. These four sample groups were analyzed with regard to oil properties, element contents, and fatty acid profiles. Measured values differed greatly between the two harvests, probably owing to different climatic or storage conditions. No direct relation between age of trees or location and oil quality could be established. The analyses indicate that J. mahafalensis oil can be used in oil lamps, cooking stoves and stationary combustion engines for electrification or for biodiesel production. However, modifications in storage and extraction methods, as well as further processing steps are necessary to enable its utilization as a straight vegetable oil and feedstock for biodiesel production. If these technical requirements can be met, and if it turns out that J. mahafalensis oil is economically competitive in comparison with firewood, charcoal, paraffin and petroleum, it can be considered as a promising feedstock for rural energy supply.
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Estrogens have been implicated in the normal and neoplastic development of the mammary gland. Although estradiol is essential for early mammary differentiation, its role in postnatal ductal morphogenesis is poorly defined. We have found that neonatal estradiol exposure promotes precocious ductal outgrowth and terminal end bud formation in 21 day-old female mice. In contrast to this precocious phenotype, day 21 estradiol-treated epithelium, transplanted into control host fatpads, grows more slowly than control epithelium. Western and immunohistochemical (IHC) analyses indicate that neonatally-estrogenized glands have significantly less total ER than controls at days 7 and 21, and significantly more stromal ER at day 35. Estrogen receptor α (ER) is present in the gland when treatment is initiated at day 1. We propose that the premature activation of ER by neonatal estradiol exposure, during this critical perinatal period, is a key factor in the alteration of mammary growth and ER expression. ^ To address the role of ER function in mammary morphogenesis, we have developed an in vitro system to study the effect of estradiol exposure in vivo. Keratin and ER-positive mammary epithelial cell lines from 7, 21 and 35 day-old oil or estradiol treated mice have been established. Cell lines derived from estradiol-treated mice grow significantly slower than cells from control glands. Although the level of ER expressed by each cell line is correlated to its rate of growth, epithelial growth in vitro is estradiol-independent and antiestrogen-insensitive. Estradiol-induced transcription from an ERE-reporter in transiently-transfected cell lines confirms the functionality of the ER detected by western and IHC. However, there are no differences in estradiol-stimulated transcription between cell lines. ^ In conclusion, neonatal estradiol treatment alters the pattern of ER expression in mammary epithelial and stromal cells in vivo, and the growth of mammary epithelial cells in vivo and in vitro. When grown outside of the estrogenized host, exposed epithelium grows more slowly than the control. Therefore, an extra-epithelial factor is necessary for enhanced epithelial growth. Our model, which couples an in vivo-in vitro approach, can be used in the future to identify factors involved in the period of early mammary outgrowth and carcinogen susceptibility. ^
Resumo:
Patients with first-episode psychosis (FEP) often show dysfunctional coping patterns, low self-efficacy, and external control beliefs that are considered to be risk factors for the development of psychosis. Therefore, these factors should already be present in patients at-risk for psychosis (AR). We compared frequencies of deficits in coping strategies (Stress-Coping-Questionnaires, SVF-120/SVF-KJ), self-efficacy, and control beliefs (Competence and Control Beliefs Questionnaire, FKK) between AR (n=21) and FEP (n=22) patients using a cross-sectional design. Correlations among coping, self-efficacy, and control beliefs were assessed in both groups. The majority of AR and FEP patients demonstrated deficits in coping skills, self-efficacy, and control beliefs. However, AR patients more frequently reported a lack of positive coping strategies, low self-efficacy, and a fatalistic externalizing bias. In contrast, FEP patients were characterized by being overly self-confident. These findings suggest that dysfunctional coping, self-efficacy, and control beliefs are already evident in AR patients, though different from those in FEP patients. The pattern of deficits in AR patients closely resembles that of depressive patients, which may reflect high levels of depressiveness in AR patients. Apart from being worthwhile treatment targets, these coping and belief patterns are promising candidates for predicting outcome in AR patients, including the conversion to psychosis
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Recently, offshoring of information systems (IS) services to external vendors has seen considerable growth. Outsourcing to vendors in foreign countries brings about unique challenges which need to be understood and managed effectively. This paper explores cultural differences in IS offshoring arrangements involving German client organizations that outsource application development activities to Indian vendors. For this purpose, a research framework is developed based on both theoretical considerations and specific empirical observations from multiple case studies. The goal is to (1) explore the nature of cultural differences in offshoring arrangements in depth and to (2) analyze the relationship between those cultural differences and offshoring success. Based on the case findings, implications and practices for the management of offshore development projects are outlined.