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Journal articles on the topic "COP rotational component"
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Ospina-Zamudio, J., B. Lefloch, C. Ceccarelli, C. Kahane, C. Favre, A. López-Sepulcre, and M. Montarges. "First hot corino detected around an isolated intermediate-mass protostar: Cep E-mm." Astronomy & Astrophysics 618 (October 2018): A145. http://dx.doi.org/10.1051/0004-6361/201832857.
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Context. Intermediate-mass (IM) protostars provide a bridge between the low- and high-mass protostars. Despite their relevance, little is known about their chemical diversity. Aims. We want to investigate the molecular richness towards the envelope of I-M protostars and to compare their properties with those of low- and high-mass sources. Methods. We have selected the isolated IM Class 0 protostar Cep E-mm to carry out an unbiased molecular survey with the IRAM 30 m telescope between 72 and 350 GHz with an angular resolution lying in the range 7–34″. Our goal is to obtain a census of the chemical content of the protostellar envelope. These data were complemented with NOEMA observations of the spectral bands 85.9–89.6 GHz and 216.8–220.4 GHz at angular resolutions of 2.3″ and 1.4″, respectively. Results. The 30 m spectra show bright emission of O- and N-bearing complex organic molecules (COMs): CH3OH and its rare isotopologues CH2DOH and 13CH3OH, CH3CHO, CH3OCH3, CH3COCH3, HCOOH, HCOOCH3, H2CCO, NH2CHO, CH3CN, C2H3CN, C2H5CN, HNCO and H2CO. We identify up to three components in the spectral signature of COMs: an extremely broad line (eBL) component associated with the outflowing gas (FWHM > 7kms−1), a narrow line (NL) component (FWHM < 3kms−1) associated with the cold envelope, and a broad line (BL) component (FWHM ≃ 5.5kms−1) which traces the signature of a hot corino. The eBL and NL components are detected only in molecular transitions of low excitation and dominate the emission of CH3OH. The BL component is detected in highly excited gas (Eup > 100 K). The NOEMA observations reveal Cep E-mm as a binary protostellar system, whose components, Cep E-A and Cep E-B, are separated by ≈1.7″. Cep E-A dominates the core continuum emission and powers the long-studied, well-known, high-velocity jet associated with HH377. The lower flux source Cep E-B powers another high-velocity molecular jet, reaching velocities of ≈80 km s−1, which propagates in a direction close to perpendicular with respect to the Cep E-A jet. Our interferometric maps show that the emission of COMs arises from a region of ≈0.7″ size around Cep E-A, and corresponds to the BL component detected with the IRAM 30 m telescope. On the contrary, no COM emission is detected towards Cep E-B. We have determined the rotational temperature (Trot) and the molecular gas column densities from a simple population diagram analysis or assuming a given excitation temperature. Rotational temperatures of COMs emission were found to lie in the range 20−40 K with column densities ranging from a few times 1015 cm−2 for O-bearing species, down to a few times 1014 cm−2 for N-bearing species. Molecular abundances are similar to those measured towards other low- and intermediate-mass protostars. Ketene (H2CCO) appears as an exception, as it is found significantly more abundant towards Cep E-A. High-mass hot cores are significantly less abundant in methanol and N-bearing species are more abundant by two to three orders of magnitude. Conclusions. Cep E-mm reveals itself as a binary protostellar system with a strong chemical differentiation between both cores. Only the brightest component of the binary is associated with a hot corino. Its properties are similar to those of low-mass hot corinos.
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Sergison, Darryl J., Tim Naylor, S. P. Littlefair, Cameron P. M. Bell, and C. D. H. Williams. "Characterizing the i-band variability of YSOs over six orders of magnitude in time-scale." Monthly Notices of the Royal Astronomical Society 491, no. 4 (December 4, 2019): 5035–55. http://dx.doi.org/10.1093/mnras/stz3398.
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ABSTRACT We present an i-band photometric study of over 800 young stellar objects in the OB association Cep OB3b, which samples time-scales from one minute to 10 yr. Using structure functions we show that on all time-scales (τ) there is a monotonic decrease in variability from Class I to Class II through the transition disc (TD) systems to Class III, i.e. the more evolved systems are less variable. The Class Is show an approximately power-law increase (τ0.8) in variability from time-scales of a few minutes to 10 yr. The Class II, TDs, and Class III systems show a qualitatively different behaviour with most showing a power-law increase in variability up to a time-scale corresponding to the rotational period of the star, with little additional variability beyond that time-scale. However, about a third of the Class IIs shows lower overall variability, but their variability is still increasing at 10 yr. This behaviour can be explained if all Class IIs have two primary components to their variability. The first is an underlying roughly power-law variability spectrum, which evidence from the infrared suggests is driven by accretion rate changes. The second component is approximately sinusoidal and results from the rotation of the star. We suggest that the systems with dominant longer time-scale variability have a smaller rotational modulation either because they are seen at low inclinations or have more complex magnetic field geometries. We derive a new way of calculating structure functions for large simulated data sets (the ‘fast structure function’), based on fast Fourier transforms.
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Hoeppner, J. W., M. H. Entz, B. G. McConkey, R. P. Zentner, and C. N. Nagy. "Energy use and efficiency in two Canadian organic and conventional crop production systems." Renewable Agriculture and Food Systems 21, no. 1 (March 2006): 60–67. http://dx.doi.org/10.1079/raf2005118.
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AbstractA goal in sustainable agriculture is to use fossil fuel energy more efficiently in crop production. This 12-year study investigated effects of two crop rotations and two crop production systems (organic versus conventional management) on energy use, energy output and energy-use efficiency. The grain-based rotation included wheat (Triticum aestivumL.)–pea (Pisum sativumL.)–wheat–flax (Linum usitatissimumL.), while the integrated rotation included wheat–alfalfa (Medicago sativaL.)–alfalfa–flax. Energy use was 50% lower with organic than with conventional management, and approximately 40% lower with integrated than with the grain-based rotation. Energy use across all treatments averaged 3420 MJ ha−1yr−1. Energy output (grain and alfalfa herbage only) across treatments averaged 49,947 MJ ha−1yr−1and was affected independently by production system and crop rotation. Energy output in the integrated rotation was three times that of the grain-based rotation; however, this difference was largely due to differences in crop type (whole plant alfalfa compared with grain seed). Energy output was 30% lower with organic than with conventional management. Energy efficiency (output energy/input energy) averaged to 17.4 and was highest in the organic and integrated rotations. A significant rotation by production system interaction (P<0.05) indicated that energy efficiency increases due to crop input reduction (i.e., shift from conventional to organic management) were greater in the integrated than in the grain-based rotation. Greater energy efficiency in the integrated rotation under organic management was attributed to the fact that the forage component was less sensitive to chemical input removal than grain crops.
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He, Dun-Chun, Yan-Li Ma, Zhuan-Zhuan Li, Chang-Sui Zhong, Zhao-Bang Cheng, and Jiasui Zhan. "Crop Rotation Enhances Agricultural Sustainability: From an Empirical Evaluation of Eco-Economic Benefits in Rice Production." Agriculture 11, no. 2 (January 21, 2021): 91. http://dx.doi.org/10.3390/agriculture11020091.
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Cropping systems greatly impact the productivity and resilience of agricultural ecosystems. However, we often lack an understanding of the quantitative interactions among social, economic and ecological components in each of the systems, especially with regard to crop rotation. Current production systems cannot guarantee both high profits in the short term and social and ecological benefits in the long term. This study combined statistic and economic models to evaluate the comprehensive effects of cropping systems on rice production using data collected from experimental fields between 2017 and 2018. The results showed that increasing agricultural diversity through rotations, particularly potato–rice rotation (PR), significantly increased the social, economic and ecological benefits of rice production. Yields, profits, profit margins, weighted dimensionless values of soil chemical and physical (SCP) and heavy metal (SHM) traits, benefits and externalities generated by PR and other rotations were generally higher than successive rice cropping. This suggests that agricultural diversity through rotations, particularly PR rotation, is worth implementing due to its overall benefits generated in rice production. However, due to various nutrient residues from preceding crops, fertilizer application should be rationalized to improve the resource and investment efficiency. Furthermore, we internalized the externalities (hidden ecological and social benefits/costs) generated by each of the rotation systems and proposed ways of incenting farmers to adopt crop rotation approaches for sustainable rice production.
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Mohr, R. M., D. A. Derksen, C. A. Grant, D. L. McLaren, M. A. Monreal, A. M. Moulin, M. Khakbazan, and R. B. Irvine. "Effect of nitrogen fertilizer rate, herbicide rate, and soil disturbance at seeding on the productivity of a wheat-pea rotation." Canadian Journal of Plant Science 87, no. 2 (April 1, 2007): 241–53. http://dx.doi.org/10.4141/p05-226.
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Rotational productivity is a function of the rotational crops and their interactions, as well as the management employed. Understanding the functioning of the overall production system, as well as its component parts, may contribute to improved management. Effects of nitrogen fertilizer rate (25, 50, 75, 100 kg N ha-1 as urea) and herbicide rate (66 or 100% of recommended) applied to wheat, and of the level of soil disturbance at seeding, on the productivity and N status of a 2-yr rotation of spring wheat (Triticum aestivum L.) and field pea (Pisum sativum L.) were assessed over two rotation cycles at two locations in southwestern Manitoba. Management factors typically acted independently to influence the cropping system. In both wheat and pea, high soil disturbance at seeding reduced or tended to reduce plant density in most site-years, resulting in reduced yields in about half of site-years. In 2 site-years where weed pressure was high, wheat yields for high disturbance treatments were less than 60% of low disturbance seeding, demonstrating the importance of adequate plant stands under sub-optimal growing conditions. The herbicide rate applied to wheat had few significant effects on wheat and pea. In most site-years, N fertilization had limited or negative effects on wheat yields due partly to relatively high soil NO3-N levels. Soil NO3-N levels declined over the years of the study, suggesting that N contributions from peas did not exceed crop N removal and/or N losses from the wheat-pea rotation. The N rate applied to wheat typically did not affect pea yields. Key words: Wheat, pea, rotation, herbicide, nitrogen, soil disturbance
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Arumugasamy, Prakash, and Dipanjan Mitra. "Evaluating the evidence of multipolar surface magnetic field in PSR J0108–1431." Monthly Notices of the Royal Astronomical Society 489, no. 4 (August 19, 2019): 4589–605. http://dx.doi.org/10.1093/mnras/stz2299.
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ABSTRACT PSR J0108–1431 is an old pulsar where the X-ray emission is expected to have a thermal component from the polar cap and a non-thermal component from the magnetosphere. Although the phase-integrated spectra are fit best with a single non-thermal component modelled with a power law (PL) of photon index Γ = 2.9, the X-ray pulse profiles do show the presence of phase-separated thermal and non-thermal components. The spectrum extracted from half the rotational phase away from the X-ray peak fits well with either a single blackbody (BB) or a neutron star atmosphere (NA) model, whereas the spectrum from the rest of the phase range is dominated by a PL. From Bayesian analysis, the estimated BB area is smaller than the expected polar cap area for a dipolar magnetic field with a probability of 86 per cent, whereas the area estimate from the NA model is larger with a probability of 80 per cent. Due to the ambiguity in the thermal emission model, the polar cap area cannot be reliably estimated and hence cannot be used to understand the nature of the surface magnetic field. Instead, we can infer the presence of multipolar magnetic field from the misalignment between the pulsar’s thermal X-ray peak and the radio emission peak. For J0108–1431, we estimated a phase-offset Δϕ > 0.1 between the thermal polar cap emission peak and the radio emission peak and argue that this is best explained by the presence of a multipolar surface magnetic field.
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Anderson, Randy L., Clair E. Stymiest, Bruce A. Swan, and John R. Rickertsen. "Weed Community Response to Crop Rotations in Western South Dakota." Weed Technology 21, no. 1 (March 2007): 131–35. http://dx.doi.org/10.1614/wt-06-011.1.
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Producers in the semiarid Great Plains are exploring alternative crop rotations, with the goal of replacing winter wheat–fallow. In 1993, a study was established to compare performance of eight rotations comprised of various combinations with winter wheat (W), spring wheat (SW), dry pea (Pea), safflower (Saf), corn (C), sunflower (Sun), proso millet (M), or fallow (F). After 8 years, we characterized weed communities by recording seedling emergence in each rotation. Seventeen species were observed, with downy brome, kochia, horseweed, and stinkgrass comprising 87% of the community. Rotations with the least number of weed seedlings were W–F and SW–W–C–Sun; in comparison, weed density was six-fold higher in W–M. Density of downy brome and kochia was highest in W–M compared with other rotations, whereas stinkgrass and green foxtail were prominent in proso millet of the W–M and W–C–M rotations. Horseweed established readily in safflower and dry pea. In the semiarid Great Plains, designing rotations in a cycle of four that includes cool- and warm-season crops can be a key component of integrated weed management.
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Wu, Teng, Fanting Kong, Lei Shi, Qing Xie, Yongfei Sun, and Changlin Chen. "Power Consumption Influence Test of Castor Disc-Cutting Device." Agriculture 12, no. 10 (September 23, 2022): 1535. http://dx.doi.org/10.3390/agriculture12101535.
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This study theoretically analyzed the cutting process of castor and determined the structural parameters of the key component of the castor disc-cutting device, aiming to obtain the optimal operation parameter combination and reduce the cutting resistance and power consumption during the harvesting process. The effects of the cutting-disc thickness, cutting-disc rotational speed, feeding speed, and edge angle on the cutting power consumption were studied using an orthogonal rotation combination experiment. The response surface method was used to optimize the parameters, and the mathematical relationship model between the cutting power consumption and each factor was established to determine the optimal parameter combination for disc cutting. The simulation results showed that the optimal combination of cutting parameters was cutting-disc thickness of 3 mm, cutting-disc rotational speed of 550 r/min, feeding speed of 0.6 m/s, and edge angle of 20°. Under these conditions, the cutting power consumption was 1.20375 J. The test results were basically consistent with the model prediction results. Therefore, this study provided a theoretical basis and reference for the design and improvement of castor harvesters.
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Blackshaw, Robert E. "Rotation Affects Downy Brome (Bromus tectorum) in Winter Wheat (Triticum aestivum)." Weed Technology 8, no. 4 (December 1994): 728–32. http://dx.doi.org/10.1017/s0890037x00028591.
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Downy brome control in winter wheat is often inadequate. The effects of three crop rotations and two tillage intensities on downy brome populations and associated crop yields were determined in an experiment at Lethbridge, Alberta from 1987 to 1993. Downy brome densities in continuous winter wheat increased from 24 to 970 plants/m2between 1988 and 1993; and were often higher with zero tillage. Inclusion of fallow or spring canola in rotation with winter wheat suppressed downy brome densities to less than 55 and 100 plants/m2, respectively, over the six years. In continuous winter wheat, yields decreased as downy brome densities increased progressively over years, indicating that monoculture winter wheat production will not be viable in regions where downy brome is prevalent unless effective herbicides are developed. In the more arid areas of the Canadian prairies, a winter wheat-fallow rotation may be most suitable but in higher precipitation areas, a winter wheat-canola rotation is a viable alternative. Crop rotation is a key component of an improved management system for control of downy brome.
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NEKRASENKO, L. A. "TAX INCENTIVES TO MANAGE LAND AS A NATURAL ASSET." Economic innovations 24, no. 1(82) (March 20, 2022): 122–29. http://dx.doi.org/10.31520/ei.2022.24.1(82).122-129.
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Topicality. Successful economic development of agriculture is one of the components of Ukraine's sustainable development. But this development very often leads to changes in natural and climatic conditions and to increased risks for doing business. Agricultural land is a natural asset and it should be taken into account that the change oflandscapes from natural vegetation to any other use can lead to loss, degradation, and fragmentation of the environment, all of which can have devastating consequences for biodiversity as a source of ecosystem services. Therefore, it is important to find ways to rationally manage the land.Aim and tasks. The purpose of our study was to substantiate the relevance of taxes for the management and rational use of land as a natural asset. As a tool, we consider a tax on crop rotation, which leads to a decrease in soil fertility and the release of carbon from dying plant residues. Crop rotation planning will help reprioritize crop selection, increase fertility and reduce carbon emissions.Research results. The main component of the sustainable development of the agricultural sector is soil fertility. At the same time, land use and agriculture are the main natural agents for reducing air pollution. Today, agriculture accounts for about 20% of greenhouse gas emissions, and humus losses range from 19% to 22% in different natural areas. Considering agricultural land as a natural asset, it should be taken into account that their irrational use leads to a change in natural and climatic conditions and an increase in risks for doing business. We have proposed to introduce carbon crop rotations as a tool for soil quality management. In our opinion, this should contribute to a change in priorities in the choice of agricultural crops, and as a result, an increase in fertility and an increase in carbon sequestration. To stimulate agricultural enterprises, we consider it expedient to introduce a tax on crop rotation. To substantiate this idea, we have created a model for the dependence of CO2 absorption/emission on the yield of various crops and a decision-making model for planning the costs of an agricultural enterprise.Conclusion. We have conducted a study of the relationship between the yield of various crops and the absorption/release of carbon dioxide. We put forward a hypothesis: there is a certain relationship between the yield of different crops and the balance of absorption/release of CO2. We have studied this connection. The model of dependence of CO2 uptake/emission on the yield of different crops shows that the ability to release carbon by plant residues of different agricultural crops has both a direct and inverse relationship with the yield of various crops. We have developed a decision-making model for planning the costs of an enterprise, subject to planning for environmental risks or paying a tax on carbon crop rotations. Thus, the problems of land use as a natural asset in agriculture can be solved by: the introduction of carbon crop rotations, which should help change priorities in the choice of agricultural crops, and the introduction of a balanced and evidence-based approach to the development and implementation of environmental taxes.
Book chapters on the topic "COP rotational component"
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Sturm, V., L. Gronewäller, P. Loosen, and H. Schülke. "Temporal Measurement of CO2-Laser Output Resolved into Transverse Direction, Polarization Components and Rotational Transitions." In Laser/Optoelektronik in der Technik / Laser/Optoelectronics in Engineering, 87–92. Berlin, Heidelberg: Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-48372-1_17.
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Burlaka, Serhiy, and Tetiana Yemchik. "IMPROVING THE EFFICIENCY OF THE USE OF BIODIESEL FUEL MIXTURES IN THE SYSTEMS OF AUTONOMOUS ENERGY SUPPLY OF AGRICULTURAL ENTERPRISES." In Modernization of research area: national prospects and European practices. Publishing House “Baltija Publishing”, 2022. http://dx.doi.org/10.30525/978-9934-26-221-0-9.
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The research is devoted to solving important tasks of interdisciplinary research work on the topic: «Development of scientific and technical support for energy autonomy of the agro-industrial complex based on environmentally efficient use of agrobiomass for biofuel production», state registration number 0122U000844, implementation of which is planned for 2022–2024 at the expense of the state budget of Ukraine.The use of fossil fuels leads to environmental pollution and climate change in general. To ensure energy security and to improve the environmental conditions necessary for the use of alternative energy sources and to determine their potential impact on the climate and our planet. Looking for more in-depth analysis of all aspects of the use of biofuels in order to determine their potential through the use and economic components.During studies carried out comparing the performance of different fuels. It has been found that the fuel obtained from biomass is advantageous in environmental protection performance in the production process, is absorbed when the biomass in the growth process and the carbon dioxide in operation.Analyzing the following requirements fuel when executed estimate (European) emission standards (CO, ShNu, NO X) for the test cycle, reduced CO2 emissions, the minimum consumption of natural resources and energy, and minimal impact on the environment in its life cycle. There are theoretical ways to increase the effective capacity of machine units and to determine the impact of this increase on the technical, economic and environmental efficiency of a diesel internal combustion engine. It has been found that the use of biofuels from plant oils can reduce the use of fossil fuels and environmental improvements. However, when using a fuel, wherein the content of the organic component exceeds 50%, i.e. deterioration of technical and economic parameters of the diesel engine. Among the mixed fuel we studied the best technical and economic characteristics of a mixture containing 70% of mineral fuels and biofuels 30% rapeseed oil. Thus, the subject to reach a dosage adjustment of the change of the fuel mixture, depending on the speed of rotation of the crankshaft of the engine the best environmental performance.
Conference papers on the topic "COP rotational component"
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Young, Bruce A., and Richard J. Olson. "System Stiffness and Restraint Effects on Circumferential Crack Opening Displacements: A Rotational Stiffness Approach." In ASME 2015 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/pvp2015-45404.
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Current crack opening displacement (COD) solutions for leak-before-break (LBB) analyses assume the ends of the cracked pipe, which is subjected to remote bending and internal pressure, are free to rotate. However, in plant piping systems, the pressure induced bending and imposed rotations are restrained, because the ends of the pipe are constrained by the rest of the piping system and other components. Hence, existing evaluation procedures, theoretically overestimate the COD values of a circumferential through-wall crack (TWC) in a piping system. These overestimations comprise one of the uncertainties in an LBB analysis, as it leads to an under-prediction of the leakage-size-crack length of a postulated leaking TWC for a prescribed leakage detection limit in a plant, and thus, results in a non-conservative estimation of the crack stability from an LBB perspective. Historical efforts on the effects of restraint on COD have focused on a restraint distance from the crack to restrain the rotation of the pipe. This study provides a fundamentally different approach in that the underlying theory develops a relationship between the apparent rotational stiffness of a pipe with unrestrained ends and the material modulus as a function of crack length and pipe geometry. Thus, the local system stiffness from a plant structural model can be used to modify the unrestrained value of COD.
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Lombardo, P. "Tracking filters for translational and rotational motion components of high resolution radar targets." In 2002 International Radar Conference (Radar 2002). IEE, 2002. http://dx.doi.org/10.1049/cp:20020302.
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Lambropoulos, John, and Don Golin. "Cutter Marks as Vibration-Induced Errors in Deterministic Microgrinding." In Optical Fabrication and Testing. Washington, D.C.: Optica Publishing Group, 1994. http://dx.doi.org/10.1364/oft.1994.omb3.
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Cutter marks, often referred to as mid-spatial frequency errors during deterministic microgrinding, have been observed on the surface of ground spherical components in a series of experiments at the Center for Optics Manufacturing (COM) at the University of Rochester. A simple model is presented to explain the recent observation that the number of cutter marks N during deterministic microgrinding of spherical components is approximately equal to the ratio of tool rotational rate fT (rpm) to work rotational rate fW for a wide range of these parameters. The model is based on the fundamental assumption that both the tool and the work execute steady-state, forced harmonic oscillations, each at its respective driving frequency, and on the observation that for each revolution of the work, the tool executes fT/fW revolutions.
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Hacks, Alexander, Sebastian Schuster, Hans Josef Dohmen, Friedrich-Karl Benra, and Dieter Brillert. "Turbomachine Design for Supercritical Carbon Dioxide Within the sCO2-HeRo.EU Project." In ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-75154.
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The paper aims to give an overview over the keystones of design of the turbomachine for a supercritical CO2 (sCO2) Brayton cycle. The described turbomachine is developed as part of a demonstration cycle on a laboratory scale with a low through flow. Therefore the turbomachine is small and operates at high rotational speed. To give an overview on the development the paper is divided into two parts regarding the aerodynamic and mechanical design. The aerodynamic design includes a detailed description on the steps from choosing an appropriate rotational speed to the design of the compressor impeller. For setting the rotational speed the expected high windage losses are evaluated considering the reachable efficiencies of the compressor. The final impeller design includes a description of the blading development together with the final geometry parameters and calculated performance. The mechanical analysis shows the important considerations for building a turbomachine with integrated design of the three major components turbine, alternator and compressor (TAC). It includes different manufacturing techniques of the impellers, the bearing strategy, the sealing components and the cooling of the generator utilising the compressor leakage. Concluding the final design of the TAC is shown and future work on the machine is introduced.
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Badami, Marco, Mauro Ferrero, and Armando Portoraro. "Simulation Model and Experimental Validation of a CHP Plant With Micro Gas Turbine." In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-89423.
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The paper deals with a simulation model, developed in Matlab Simulink®, of a small-scale Combined Heat and Power (CHP) plant based on a recuperated micro gas turbine (mGT). A minimum data set, mainly obtainable from datasheets, was defined, that allows the model to simulate different mGT plants in the small-scale range with a good accuracy. The model implements the mass, energy and momentum equations of the main components of the power plant. A double control system has also been developed, with the aim of maintaining the rotational speed of the turbine /compressor assembly at the nominal fixed value, and at limiting the Exhaust Gas Temperature (EGT) below the limit value. The model has been validated by means of experimental data obtained from a commercial mGT (100 kWel, 170 kWth), installed at the Politecnico di Torino, whose energetic characterization has been performed both at rated and at partial load conditions. The layout and the characteristics of the measurement system are also described in the paper.
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Sukhovii, Sergii I., Feliks F. Sirenko, Sergiy V. Yepifanov, and Igor Loboda. "Alternative Method to Simulate a Sub-Idle Engine Operation in Order to Synthesize Its Control System." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-25960.
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The steady-state and transient engine performances of gas turbine control system development are usually evaluated by applying full thermodynamic engine models. Most models only address the operating range between the idle and maximum power points, but more recently, they also address a sub-idle operating range. The lack of information about the component maps at the sub-idle modes creates major challenges for the starting system and control system designers. A common method to cope with the problem extrapolates the performances of the engine components to the sub-idle operation range. Precise extrapolation is a challenge to be studied by many scientists. As a rule, many scientists are only concerned about particular aspects of the problem such as the lighting combustion chamber or the turbine operation under the turned-off conditions of the combustion chamber. However, there are no known reports about a model that considers all of these mentioned aspects and simulates the engine starting. To synthesize a thermodynamic model of starting, most known methods require the performance of the components in the sub-idle range. The proposed paper addresses a new method that simulates the engine starting. The method substitutes the non-linear thermodynamic model with a linear dynamic model, which is supplemented with a simplified static model. The latter model is the set of direct relations between parameters that are used in the control algorithms instead of commonly used component performances. Specifically, the static model consists of simplified relations between the gas path parameters and the corrected rotational speed. The paper also describes an algorithm for model synthesis and its practical application to real data.
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Cho, Jongjae, Hyungki Shin, Junhyun Cho, Young-Jin Baik, Bongsu Choi, Chulwoo Roh, Ho-Sang Ra, Youngseok Kang, and Jaesung Huh. "Design, Flow Simulation, and Performance Test for a Partial-Admission Axial Turbine Under Supercritical CO2 Condition." In ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-76508.
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The development of a 60-kWe turbo generator that uses supercritical carbon dioxide (sCO2) cycle technology at the lab scale is described herein. The design concept for the turbo generator involved using commercially available components to reduce the developmental time and to increase the reliability of the machine. The developed supercritical partial-admission CO2 turbine has a single-stage axial-type design with a 73-mm rotor mean diameter. The design of the sCO2 turbine uses impulse and partial admission to reduce the axial force and rotational speed. We simulated the flow of the designed sCO2 turbine. To increase the simulation accuracy, a real gas property table is coupled with the flow solver. The turbine performance test apparatus and test results are described; then, the turbine is continuously operated for 44 min. The maximum turbine power is 25.4 kW, and the maximum electric power is 10.3 kWe.
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Hasuike, Hiroshi, Takashi Yamamoto, Toshihiko Fukushima, Toshinori Watanabe, Motoaki Utamura, and Masanori Aritomi. "Test Plan and Preliminary Test Results of a Bench Scale Closed Cycle Gas Turbine With Super-Critical CO2 as Working Fluid." In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-22171.
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Development of a closed cycle gas turbine using supercritical carbon dioxide as a working fluid is underway to generate power from industrial waste heat sources of a low or intermediate temperature range. Its demonstration test plan using a reduced scale turbomachine is described herein. Principal specifications include the following: net power output of 10 kWe and recirculation CO2 with flow rate of 1.2 kg/s under given turbine inlet conditions of 550 K and 12 MPa. The optimized ranges of compressor inlet temperatures and pressures are investigated in this study. Given these inlet conditions, primary and auxiliary component development is done. Coupled with cycle analysis, the design rotational speed of the co-axially aligned turbomachine was determined as 100,000 rpm. Aerodynamic CFD analyses were conducted for the centrifugal compressor considering real gas properties. Preliminary test results show indirect evidence of compressor work reduction inherent to the supercritical CO2 gas turbine concept.
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Sanz, W., H. Jericha, B. Bauer, and E. Go¨ttlich. "Qualitative and Quantitative Comparison of Two Promising Oxy-Fuel Power Cycles for CO2 Capture." In ASME Turbo Expo 2007: Power for Land, Sea, and Air. ASMEDC, 2007. http://dx.doi.org/10.1115/gt2007-27375.
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Since the Kyoto conference there is a broad consensus that the human emission of greenhouse gases, mainly CO2, has to be reduced. In the power generation sector there are three main alternatives which are currently studied world wide. Among them oxy-fuel cycles with internal combustion with pure oxygen are a very promising technology. Within the European project ENCAP — ENhanced CO2 CAPture — the benchmarking of a number of novel power cycles with CO2 capture was carried out [1]. Within the category oxy-fuel cycles the Graz Cycle and the Semi-Closed Oxy-Fuel Combustion Combined Cycle (SCOC-CC) both achieved a net efficiency of nearly 50%. In a second step a qualitative comparison of the critical components was performed according to their technical maturity. In contrast to the Graz Cycle the study authors claimed that no major technical barriers would exist for the SCOC-CC. In this work the ENCAP study is repeated for the SCOC-CC and for a modified Graz Cycle variant as presented at the ASME IGTI conference 2006 [2]. Both oxy-fuel cycles are thermodynamically investigated based on common assumptions agreed with industry in previous work. The calculations showed that the high-temperature turbine of the SCOC-CC plant needs a much higher cooling flow supply due to the less favorable properties of the working fluid. A layout of the main components of both cycles is further presented which shows that both cycles rely on the new designs of the high-temperature turbine and the compressors. The SCOC-CC compressor needs more stages due to a lower rotational speed but has a more favorable operating temperature. In general, all turbomachines of both cycles show similar technical challenges and are regarded as feasible.
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Breckel, Alex, Altan Ozkan, and Halil Berberoglu. "Steady and Dynamic Rheological Properties of Dense Slurries of Chlorella vulgaris." In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-64123.
Full textAbstract:
This experimental study reports the steady and dynamic rheological properties of dense slurries of the green algae Chlorella vulgaris. Biofuel production from algae growth is a promising technology that has the potential to serve as a significant component of the world’s revised energy mix. Along with providing a renewable fuel source, algae production acts as a CO2 sink, potentially reducing net CO2 emissions. Design and operation of algae biofuel production facilities require accurate knowledge of the flow characteristics of algae slurries and estimation of the pumping and harvesting energy requirements. Reliable rheological data is needed to optimize production processes to lower costs and increase yields. This study reports steady state viscosity measurements conducted using the ARES TA rotational rheometer using the common algae strain Chlorella vulgaris over the packing factor range from 0.1 to 0.8. Viscoelastic data was gathered using oscillatory tests conducted on the rotational rheometer with a double wall coquette fixture geometry. Dynamic frequency sweep tests were used to recover the storage shear modulus (G′), and the loss shear modulus (G″), which correspond to the elastic and viscous properties of the fluid, respectively. Apparent viscosity of the cell suspensions increased with increasing packing factors. Packing factors lower than 0.3 exhibited Newtonian characteristics, whereas at larger packing factors the behavior was shear-thinning. The algae suspensions exhibited both viscous and elastic behavior when subjected to oscillatory flow, behaving as a dilute solution. Finally, the frequency of the gel point increased with increasing packing factor.