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Статті в журналах з теми "System Equivalent Model Mixing"
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Klaassen, Steven W. B., Maarten V. van der Seijs, and Dennis de Klerk. "System equivalent model mixing." Mechanical Systems and Signal Processing 105 (May 2018): 90–112. http://dx.doi.org/10.1016/j.ymssp.2017.12.003.
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Pogačar, Miha, Domen Ocepek, Francesco Trainotti, Gregor Čepon, and Miha Boltežar. "System equivalent model mixing: A modal domain formulation." Mechanical Systems and Signal Processing 177 (September 2022): 109239. http://dx.doi.org/10.1016/j.ymssp.2022.109239.
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El Abdalaoui, E. H., and M. Disertori. "Spectral properties of the Möbius function and a random Möbius model." Stochastics and Dynamics 16, no. 01 (November 10, 2015): 1650005. http://dx.doi.org/10.1142/s0219493716500052.
Повний текст джерелаАнотація:
Assuming Sarnak’s conjecture is true for any singular dynamical process, we prove that the spectral measure of the Möbius function is equivalent to Lebesgue measure. Conversely, under Elliott’s conjecture, we establish that the Möbius function is orthogonal to any uniquely ergodic dynamical system with singular spectrum. Furthermore, using Mirsky’s theorem, we find a new simple proof of Cellarosi–Sinai’s theorem on the orthogonality of the square of the Möbius function with respect to any weakly mixing dynamical system. Finally, we establish Sarnak’s conjecture for a particular random model.
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Ashrafi, S., S. Zarezadeh, and M. Asadi. "Reliability modeling of coherent systems with shared components based on sequential order statistics." Journal of Applied Probability 55, no. 3 (September 2018): 845–61. http://dx.doi.org/10.1017/jpr.2018.54.
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Abstract In this paper we are concerned with the reliability properties of two coherent systems having shared components. We assume that the components of the systems are two overlapping subsets of a set of n components with lifetimes X1,...,Xn. Further, we assume that the components of the systems fail according to the model of sequential order statistics (which is equivalent, under some mild conditions, to the failure model corresponding to a nonhomogeneous pure-birth process). The joint reliability function of the system lifetimes is expressed as a mixture of the joint reliability functions of the sequential order statistics, where the mixing probabilities are the bivariate signature matrix associated to the structures of systems. We investigate some stochastic orderings and dependency properties of the system lifetimes. We also study conditions under which the joint reliability function of systems with shared components of order m can be equivalently written as the joint reliability function of systems of order n (n>m). In order to illustrate the results, we provide several examples.
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Kodrič, Miha, Tomaž Bregar, Gregor Čepon, and Miha Boltežar. "An expansion based on System Equivalent Model Mixing: From a limited number of points to a full-field dynamic response." Measurement 190 (February 2022): 110522. http://dx.doi.org/10.1016/j.measurement.2021.110522.
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HOCHMAN, MICHAEL. "Genericity in topological dynamics." Ergodic Theory and Dynamical Systems 28, no. 1 (February 2008): 125–65. http://dx.doi.org/10.1017/s0143385707000521.
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AbstractWe study genericity of dynamical properties in the space of homeomorphisms of the Cantor set and in the space of subshifts of a suitably large shift space. These rather different settings are related by a Glasner–King type correspondence: genericity in one is equivalent to genericity in the other. By applying symbolic techniques in the shift-space model we derive new results about genericity of dynamical properties for transitive and totally transitive homeomorphisms of the Cantor set. We show that the isomorphism class of the universal odometer is generic in the space of transitive systems. On the other hand, the space of totally transitive systems displays much more varied dynamics. In particular, we show that in this space the isomorphism class of every Cantor system without periodic points is dense and the following properties are generic: minimality, zero entropy, disjointness from a fixed totally transitive system, weak mixing, strong mixing and minimal self joinings. The latter two stand in striking contrast to the situation in the measure-preserving category. We also prove a correspondence between genericity of dynamical properties in the measure-preserving category and genericity of systems supporting an invariant measure with the same property.
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Zhai, Chi, Qinjun Liu, Jose A. Romagnoli, and Wei Sun. "Modeling/Simulation of the Dividing Wall Column by Using the Rigorous Model." Processes 7, no. 1 (January 8, 2019): 26. http://dx.doi.org/10.3390/pr7010026.
Повний текст джерелаАнотація:
Dividing wall column (DWC) is an atypical distillation column with an internal, vertical WE partition wall that effectively accommodates two conventional distillation columns into one to improve the thermodynamic efficiency. In previous studies, different equivalent models by combining conventional columns are adopted to approximate the DWC modeling, which may not well describe the integration of the DWC; moreover, the computational cost increases when multiple columns are implemented to represent one DWC. In this paper, a rigorous mathematical model is proposed based on the mass balance, the energy and phase equilibrium of the DWC, where decision variables and state variables are equally treated. The model was developed in the general process modeling system (gPROMS). Based on the rigorous model, the influences of liquid split ratio and vapor split ratio are discussed, and it is shown that the heat duty is sensitive to changes on the liquid and vapor split ratio. Inappropriate liquid and vapor split ratio will increase the mixing effects at both ends of the dividing wall, and adversely affect the thermodynamic efficiency. Hence, the degree of mixing is defined to characterize the column efficiency. Furthermore, the middle component split ratio at the top of the pre-fractionator has an optimal point for better energy saving with certain liquid and vapor split ratios, and can be used as an indicator for the energy performance. Finally, the model was tested and validated against literature data by using the ternary benzene–toluene–xylene mixture system as a case study.
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Orr, J. C., and J. M. Epitalon. "Improved routines to model the ocean carbonate system: mocsy 1.0." Geoscientific Model Development Discussions 7, no. 3 (May 5, 2014): 2877–902. http://dx.doi.org/10.5194/gmdd-7-2877-2014.
Повний текст джерелаАнотація:
Abstract. Software used by modelers to compute ocean carbonate chemistry is often based on code from the Ocean Carbon Cycle Model Intercomparison Project (OCMIP), last revised in 2005. As an update, we offer here new publicly available Fortran 95 routines to model the ocean carbonate system (mocsy). Both codes take as input dissolved inorganic carbon CT and total alkalinity AT, the only two tracers of the ocean carbonate system that are unaffected by changes in temperature and salinity and conservative with respect to mixing, properties that make them ideally suited for ocean carbon models. With the same basic thermodynamic equilibria, both codes compute surface-ocean pCO2 in order to simulate air–sea CO2 fluxes. The mocsy package goes beyond the OCMIP code by computing all other carbonate system variables (e.g., pH, CO32−, and CaCO3 saturation states) and by doing so throughout the water column. Moreover, it avoids three common model approximations: that density is constant, that modeled potential temperature is equivalent to in situ temperature, and that depth is equivalent to pressure. These approximations work well at the surface, but total errors in computed variables grow with depth, e.g., reaching −8 μatm in pCO2, +0.010 in pH, and +0.01 in ΩA at 5000 m. Besides the equilibrium constants recommended for best practices, mocsy also offers users three new options: (1) a recent formulation for total boron that increases its ocean content by 4%, (2) an older formulation for KF common to all other such software, and (3) recent formulations for K1 and K2 designed to also include low-salinity waters. More total boron increases borate alkalinity and reduces carbonate alkalinity, which is calculated as a difference from total alkalinity. As a result, the computed surface pCO2 increases by 4 to 6 μatm, while the computed aragonite saturation horizon (ASH) shallows by 60 m in the North Atlantic and by up to 90 m in the Southern Ocean. Changes due to the new formulation for K1 and K2 enhance pCO2 by up to 8 μatm in the deep ocean and in high-latitude surface waters. These changes are comparable in magnitude to errors in the same regions associated with neglecting nutrient contributions to total alkalinity, a common practice in ocean biogeochemical modeling. The mocsy code with the standard options for best practices and none of the 3 approximations agrees with results from the CO2SYS package generally within 0.005%.
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Schiro, Kathleen A., and J. David Neelin. "Tropical continental downdraft characteristics: mesoscale systems versus unorganized convection." Atmospheric Chemistry and Physics 18, no. 3 (February 12, 2018): 1997–2010. http://dx.doi.org/10.5194/acp-18-1997-2018.
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Abstract. Downdrafts and cold pool characteristics for strong mesoscale convective systems (MCSs) and isolated, unorganized deep precipitating convection are analyzed using multi-instrument data from the DOE Atmospheric Radiation Measurement (ARM) GoAmazon2014/5 campaign. Increases in column water vapor (CWV) are observed leading convection, with higher CWV preceding MCSs than for isolated cells. For both MCSs and isolated cells, increases in wind speed, decreases in surface moisture and temperature, and increases in relative humidity occur coincidentally with system passages. Composites of vertical velocity data and radar reflectivity from a radar wind profiler show that the downdrafts associated with the sharpest decreases in surface equivalent potential temperature (θe) have a probability of occurrence that increases with decreasing height below the freezing level. Both MCSs and unorganized convection show similar mean downdraft magnitudes and probabilities with height. Mixing computations suggest that, on average, air originating at heights greater than 3 km must undergo substantial mixing, particularly in the case of isolated cells, to match the observed cold pool θe, implying a low typical origin level. Precipitation conditionally averaged on decreases in surface equivalent potential temperature (Δθe) exhibits a strong relationship because the most negative Δθe values are associated with a high probability of precipitation. The more physically motivated conditional average of Δθe on precipitation shows that decreases in θe level off with increasing precipitation rate, bounded by the maximum difference between surface θe and its minimum in the profile aloft. Robustness of these statistics observed across scales and regions suggests their potential use as model diagnostic tools for the improvement of downdraft parameterizations in climate models.
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Radhouane, Amina, Nejla Mahjoub Said, Hatem Mhiri, and Philippe Bournot. "Characterization of the Mixing Induced by Multiple Elevated Jets in Cross Flow." Defect and Diffusion Forum 399 (February 2020): 3–9. http://dx.doi.org/10.4028/www.scientific.net/ddf.399.3.
Повний текст джерелаАнотація:
Experimental and numerical consideration is given in the present work to an inline, inclined triple elliptic jet-group discharged in cross flow, a common configuration widely present in several domains, namely environmental, industrial and even medical. The experiments were described by particle image velocimetry and hot wire anemometry measurements, and the numerical simulation was based upon the finite volume method together with a non uniform grid system tightened close to the discharging nozzles. Generally, optimizing similar configurations is meant to reach optimum mixings in terms of heat and/or mass transfers. The present work will be particularly dedicated to the heat transfers generated within the examined multiple jet in cross flow configuration, for jets emitted under an injection height equivalent to , and under a variable injection ratio. After presenting the handled geometry, a validation of the numerical model is proposed. Afterward, a discussion of the reduced static temperature is presented. This is a highly interesting parameter due to its closeness, if not similarity under some circumstances, to the cooling efficiency.
Дисертації з теми "System Equivalent Model Mixing"
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Shamsi, Mohammad Haris. "Analysis of an electric Equivalent Circuit Model of a Li-Ion battery to develop algorithms for battery states estimation." Thesis, Uppsala universitet, Elektricitetslära, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-298427.
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Batteries have imparted momentum to the process of transition towards a green future. However, mass application of batteries is obstructed due to their explosive nature, a trait specific to Li-Ion batteries. To cater to an efficient battery utilization, an introduction of a battery management system would provide an ultimate solution. This thesis deals with different aspects crucial in designing a battery management system for high energy as well as high power applications. To build a battery management system capable of predicting battery behavior, it is necessary to analyze the dynamic processes happening inside the battery. Hence, a battery equivalent circuit model is proposed in this thesis as well as proper analysis is done in MATLAB to project a generic structure applicable to all Li-Ion chemistries. The model accounts for all dynamic characteristics of a battery including non-linear open circuit voltage, discharge current and capacity. Effect of temperature is also modeled using a cooling system. The model is validated with test current profiles. Less than 0.1% error between measured and simulated voltage profiles indicates the effectiveness of the proposed model to predict the runtime behavior of the battery. Furthermore, the model is implemented with the energy as well as the power battery pack. State of charge calculations are performed using the proposed model and the coulomb counting method and the results indicate only a 4% variance. Therefore, the proposed model can be applied to develop a real-time battery management system for accurate battery states estimation.
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Haines, Sam P. "Design and application of a smart battery management system for a small electric vehicle." Thesis, Queensland University of Technology, 2022. https://eprints.qut.edu.au/228154/1/Sam_Haines_Thesis.pdf.
Повний текст джерелаАнотація:
This thesis outlines the development and application of a battery management system for a small electric vehicle, and the hardware required to test and validate these systems. The project applies state-of-the-art methods for estimating the remaining charge of a battery pack in a real-world environment. In doing so, the limitations of existing estimation methods are identified and addressed.
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Übel, Markus [Verfasser]. "Simulation of mesoscale patterns and diurnal variations of atmospheric CO2 mixing ratios with the model system TerrSysMP-CO2 / Markus Übel." Bonn : Universitäts- und Landesbibliothek Bonn, 2016. http://d-nb.info/1107184452/34.
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Wu, Lichuan. "Introducing Surface Gravity Waves into Earth System Models." Doctoral thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-314760.
Повний текст джерелаАнотація:
Surface gravity waves alter the turbulence of the bottom atmosphere and the upper ocean. Accordingly, they can affect momentum flux, heat fluxes, gas exchange and atmospheric mixing. However, in most state-of-the-art Earth System Models (ESMs), surface wave influences are not fully considered or even included. Here, applying surface wave influences into ESMs is investigated from different aspects. Tuning parameterisations for including instantaneous wave influences has difficulties to capture wave influences. Increasing the horizontal resolution of models intensifies storm simulations for both atmosphere-wave coupled (considering the influence of instantaneous wave-induced stress) and stand-alone atmospheric models. However, coupled models are more sensitive to the horizontal resolution than stand-alone atmospheric models. Under high winds, wave states have a big impact on the sea spray generation. Introducing a wave-state-dependent sea spray generation function and Charnock coefficient into a wind stress parameterisation improves the model performance concerning wind speed (intensifies storms). Adding sea spray impact on heat fluxes improves the simulation results of air temperature. Adding sea spray impact both on the wind stress and heat fluxes results in better model performance on wind speed and air temperature while compared to adding only one wave influence. Swell impact on atmospheric turbulence closure schemes should be taken into account through three terms: the atmospheric mixing length scale, the swell-induced momentum flux at the surface, and the profile of swell-induced momentum flux. Introducing the swell impact on the three terms into turbulence closure schemes shows a better performance than introducing only one of the influences. Considering all surface wave impacts on the upper-ocean turbulence (wave breaking, Stokes drift interaction with the Coriolis force, Langmuir circulation, and stirring by non-breaking waves), rather than just one effect, significantly improves model performance. The non-breaking-wave-induced mixing and Langmuir circulation are the most important terms when considering the impact of waves on upper-ocean mixing. Accurate climate simulations from ESMs are very important references for social and biological systems to adapt the climate change. Comparing simulation results with measurements shows that adding surface wave influences improves model performance. Thus, an accurate description of all important wave impact processes should be correctly represented in ESMs, which are important tools to describe climate and weather. Reducing the uncertainties of simulation results from ESMs through introducing surface gravity wave influences is necessary.
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Khodabakhshian, Mohammad. "Improving Fuel Efficiency of Commercial Vehicles through Optimal Control of Energy Buffers." Doctoral thesis, KTH, Mekatronik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-181071.
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Fuel consumption reduction is one of the main challenges in the automotiveindustry due to its economical and environmental impacts as well as legalregulations. While fuel consumption reduction is important for all vehicles,it has larger benefits for commercial ones due to their long operational timesand much higher fuel consumption. Optimal control of multiple energy buffers within the vehicle proves aneffective approach for reducing energy consumption. Energy is temporarilystored in a buffer when its cost is small and released when it is relativelyexpensive. An example of an energy buffer is the vehicle body. Before goingup a hill, the vehicle can accelerate to increase its kinetic energy, which canthen be consumed on the uphill stretch to reduce the engine load. The simplestrategy proves effective for reducing fuel consumption. The thesis generalizes the energy buffer concept to various vehicular componentswith distinct physical disciplines so that they share the same modelstructure reflecting energy flow. The thesis furthermore improves widely appliedcontrol methods and apply them to new applications. The contribution of the thesis can be summarized as follows: • Developing a new function to make the equivalent consumption minimizationstrategy (ECMS) controller (which is one of the well-knownoptimal energy management methods in hybrid electric vehicles (HEVs))more robust. • Developing an integrated controller to optimize torque split and gearnumber simultaneously for both reducing fuel consumption and improvingdrivability of HEVs. • Developing a one-step prediction control method for improving the gearchanging decision. • Studying the potential fuel efficiency improvement of using electromechanicalbrake (EMB) on a hybrid electric city bus. • Evaluating the potential improvement of fuel economy of the electricallyactuated engine cooling system through the off-line global optimizationmethod. • Developing a linear time variant model predictive controller (LTV-MPC)for the real-time control of the electric engine cooling system of heavytrucks and implementing it on a real truck.QC 20160128
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Cordoba, Arenas Andrea Carolina. "Aging Propagation Modeling and State-of-Health Assessment in Advanced Battery Systems." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1385967836.
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Pečeliūnas, Robertas. "Automobilio svyravimai ekstremalaus stabdymo metu." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2005. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2005~D_20050224_192006-55801.
Повний текст джерелаАнотація:
The suspension of the motor vehicle is one of the most important elements of the flexible mounted and inflexible mounted masses of the vehicle bodywork, and most attention is paid to its exploration and improvement. Analysis of models of equivalent oscillation systems of motor vehicles testifies that the evaluation of motor vehicle oscillations and modelling of its motion modes is still very topical and requires further research. Suspension models of motor vehicles offered in publications regard only the influence of road irregularities, and the modernisation of these models is directed towards the improvement of passengers’ comfort. However not much research has been done on the influence of oscillations of flexible mounted and inflexible mounted masses of the bodyworks of vehicles in the process of braking; also there is not much investigation of the post-accident identification of the vehicle’s movement mode corresponding to the deformations of the suspension and the longitudinal pitch of the bodywork. Research of oscillations in the conditions of emergency braking is primarily important for the work in two practical directions:
1) improvement of calculation methods of motor vehicle’s response to external impact in the conditions of real operation;
2) further improvement of research methods on the road, and analysis of fait accompli road accidents related to oscillations in the emergency braking.
Methodology defining the oscillations occurring in the braking may be applied... [to full text]
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Kuo, Yu-chi, and 郭育齊. "The Study of Signal Integration Analysis and Equivalent Model Extracting for RF Testing System." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/5ecdjm.
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李政勳. "Equalization System with SOC Estimation Based on Equivalent Circuit Model for LCO Battery Modules." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/09118459463937977623.
Повний текст джерелаАнотація:
碩士逢甲大學
電機工程學系
103
Nowadays, the research of the battery with higher energy density is increasing. Due to the higher energy density of battery, more and more machines are powered by batteries, such as electric vehicle, electric stacker trucks, and electric boat. These battery applications must to control and manage the batteries by Battery Management System (BMS). The state of charge (SOC) of battery and the battery balancing are two very important topics of battery management system. This paper proposed an improved coulomb counting method with equivalent circuit model, by using equivalent circuit model to provide the initial SOC, and then coulomb counting method to estimate capacity. Balanced single battery capacity was made by the bi-directional DC-to-DC buck-boost converter. The battery module can have accurate estimate SOC estimation and balance ability.
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Kwasnicki, Wieslaw T. "An equivalent model generator for large scale linear networks based on a system identification approach." 1986. http://hdl.handle.net/1993/15396.
Повний текст джерелаКниги з теми "System Equivalent Model Mixing"
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Zhang, Weicun, and Qing Li. Virtual Equivalent System Approach for Stability Analysis of Model-based Control Systems. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-15-5538-1.
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F, Walker James, Trefny Charles J, and NASA Glenn Research Center, eds. Parametric studies of the ejector process within a turbine-based combined-cycle propulsion system. [Cleveland, Ohio]: National Aeronautics and Space Administration, Glenn Research Center, 1999.
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Li, Qing, and Weicun Zhang. Virtual Equivalent System Approach for Stability Analysis of Model-based Control Systems. Springer, 2020.
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Li, Qing, and Weicun Zhang. Virtual Equivalent System Approach for Stability Analysis of Model-Based Control Systems. Springer Singapore Pte. Limited, 2021.
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Li, Qing, and Weicun Zhang. Virtual Equivalent System Approach for Stability Analysis of Model-based Control Systems. Springer, 2020.
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Petroka, Robert P. Computer simulation and experimental validation of a dynamic model (equivalent rigid link system) on a single-link flexible manipulator. 1986.
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Zeitlin, Vladimir. Rotating Shallow-Water model with Horizontal Density and/or Temperature Gradients. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198804338.003.0014.
Повний текст джерелаАнотація:
The derivation of rotating shallow-water equations by vertical averaging and columnar motion hypothesis is repeated without supposing horizontal homogeneity of density/potential temperature. The so-called thermal rotating shallow-water model arises as the result. The model turns to be equivalent to gas dynamics with a specific equation of state. It is shown that it possesses Hamiltonian structure and can be derived from a variational principle. Its solution at low Rossby numbers should obey the thermo-geostrophic equilibrium, replacing the standard geostrophic equilibrium. The wave spectrum of the model is analysed, and the appearance of a whole new class of vortex instabilities of convective type, resembling asymmetric centrifugal instability and leading to a strong mixing at nonlinear stage, is demonstrated.
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Pershina, K. D., and K. O. Kazdobin. Impedance spectroscopy of electrolytic materials. V.I. Vernadsky Institute of General and Inorganic Chemistry, 2012. http://dx.doi.org/10.33609/guide.2012.224.
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Electrochemical impedance spectroscopy (EIS) is playing an increasingly significant role in fundamental and applied research: to study any type of solid and liquid materials (ionic, mixed, semiconductor, and insulators), to study charge transfer in heterogeneous systems, including phase boundaries, electrode boundaries, and elements of the microstructure. With the help of EIS, it is possible to study the behavior of chemical sensors, fuel cells, batteries, and corrosion processes. The base of the method stays on the principle of exciting any electrochemical system with a signal in the form of a sinusoidal wave and observing its behavior in response to this disturbance. This is the simplest method for determining the structural and transport functions of the system under study. This is the simplest method for determining the structural and transport functions of the system under study. The book discusses the theoretical foundations of the method of impedance spectroscopy, including the method of equivalent circuits, and provides examples of the analysis of impedance spectra for real objects. The main attention is paid to the model elements of equivalent circuits, their physical base, and the use of the models in the analysis of electrochemical systems. Handbook consists of seven chapters. It has questions and tasks to self-work after each part. It is intended for students of chemical, chemical-technological, and biomedical specialties, as well as for specialists engaged in research in the field of materials science, medicine, and ecology.
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Zeitlin, Vladimir. Rotating Shallow-Water Models with Moist Convection. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198804338.003.0015.
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It is shown how the standard RSW can be ’augmented’ to include phase transitions of water. This chapter explains how to incorporate extra (convective) vertical fluxes in the model. By using Lagrangian conservation of equivalent potential temperature condensation of the water vapour, which is otherwise a passive tracer, is included in the model and linked to convective fluxes. Simple relaxational parameterisation of condensation permits the closure of the system, and surface evaporation can be easily included. Physical and mathematical properties of thus obtained model are explained, and illustrated on the example of wave scattering on the moisture front. The model is applied to ’moist’ baroclinic instability of jets and vortices. Condensation is shown to produce a transient increase of the growth rate. Special attention is paid to the moist instabilities of hurricane-like vortices, which are shown to enhance intensification of the hurricane, increase gravity wave emission, and generate convection-coupled waves.
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Ślusarski, Marek. Metody i modele oceny jakości danych przestrzennych. Publishing House of the University of Agriculture in Krakow, 2017. http://dx.doi.org/10.15576/978-83-66602-30-4.
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The quality of data collected in official spatial databases is crucial in making strategic decisions as well as in the implementation of planning and design works. Awareness of the level of the quality of these data is also important for individual users of official spatial data. The author presents methods and models of description and evaluation of the quality of spatial data collected in public registers. Data describing the space in the highest degree of detail, which are collected in three databases: land and buildings registry (EGiB), geodetic registry of the land infrastructure network (GESUT) and in database of topographic objects (BDOT500) were analyzed. The results of the research concerned selected aspects of activities in terms of the spatial data quality. These activities include: the assessment of the accuracy of data collected in official spatial databases; determination of the uncertainty of the area of registry parcels, analysis of the risk of damage to the underground infrastructure network due to the quality of spatial data, construction of the quality model of data collected in official databases and visualization of the phenomenon of uncertainty in spatial data. The evaluation of the accuracy of data collected in official, large-scale spatial databases was based on a representative sample of data. The test sample was a set of deviations of coordinates with three variables dX, dY and Dl – deviations from the X and Y coordinates and the length of the point offset vector of the test sample in relation to its position recognized as a faultless. The compatibility of empirical data accuracy distributions with models (theoretical distributions of random variables) was investigated and also the accuracy of the spatial data has been assessed by means of the methods resistant to the outliers. In the process of determination of the accuracy of spatial data collected in public registers, the author’s solution was used – resistant method of the relative frequency. Weight functions, which modify (to varying degree) the sizes of the vectors Dl – the lengths of the points offset vector of the test sample in relation to their position recognized as a faultless were proposed. From the scope of the uncertainty of estimation of the area of registry parcels the impact of the errors of the geodetic network points was determined (points of reference and of the higher class networks) and the effect of the correlation between the coordinates of the same point on the accuracy of the determined plot area. The scope of the correction was determined (in EGiB database) of the plots area, calculated on the basis of re-measurements, performed using equivalent techniques (in terms of accuracy). The analysis of the risk of damage to the underground infrastructure network due to the low quality of spatial data is another research topic presented in the paper. Three main factors have been identified that influence the value of this risk: incompleteness of spatial data sets and insufficient accuracy of determination of the horizontal and vertical position of underground infrastructure. A method for estimation of the project risk has been developed (quantitative and qualitative) and the author’s risk estimation technique, based on the idea of fuzzy logic was proposed. Maps (2D and 3D) of the risk of damage to the underground infrastructure network were developed in the form of large-scale thematic maps, presenting the design risk in qualitative and quantitative form. The data quality model is a set of rules used to describe the quality of these data sets. The model that has been proposed defines a standardized approach for assessing and reporting the quality of EGiB, GESUT and BDOT500 spatial data bases. Quantitative and qualitative rules (automatic, office and field) of data sets control were defined. The minimum sample size and the number of eligible nonconformities in random samples were determined. The data quality elements were described using the following descriptors: range, measure, result, and type and unit of value. Data quality studies were performed according to the users needs. The values of impact weights were determined by the hierarchical analytical process method (AHP). The harmonization of conceptual models of EGiB, GESUT and BDOT500 databases with BDOT10k database was analysed too. It was found that the downloading and supplying of the information in BDOT10k creation and update processes from the analyzed registers are limited. An effective approach to providing spatial data sets users with information concerning data uncertainty are cartographic visualization techniques. Based on the author’s own experience and research works on the quality of official spatial database data examination, the set of methods for visualization of the uncertainty of data bases EGiB, GESUT and BDOT500 was defined. This set includes visualization techniques designed to present three types of uncertainty: location, attribute values and time. Uncertainty of the position was defined (for surface, line, and point objects) using several (three to five) visual variables. Uncertainty of attribute values and time uncertainty, describing (for example) completeness or timeliness of sets, are presented by means of three graphical variables. The research problems presented in the paper are of cognitive and application importance. They indicate on the possibility of effective evaluation of the quality of spatial data collected in public registers and may be an important element of the expert system.
Частини книг з теми "System Equivalent Model Mixing"
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Pogačar, Miha, Domen Ocepek, Gregor Čepon, and Miha Boltežar. "System Equivalent Model Mixing (SEMM): A Modal Domain Formulation." In Conference Proceedings of the Society for Experimental Mechanics Series, 111–14. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-04094-8_14.
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Kodrič, Miha, Tomaž Bregar, Gregor Čepon, and Miha Boltežar. "Parametric Analysis of the Expansion Process Based on System Equivalent Model Mixing." In Conference Proceedings of the Society for Experimental Mechanics Series, 97–100. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-04094-8_12.
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Dutta, Monalisa, and Soma Barman. "Electrical Equivalent Model for Gene Regulatory System." In Proceedings of the International Conference on Microelectronics, Computing & Communication Systems, 161–69. Singapore: Springer Singapore, 2017. http://dx.doi.org/10.1007/978-981-10-5565-2_14.
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Naik, Mayur, and Jens Palsberg. "A Type System Equivalent to a Model Checker." In Programming Languages and Systems, 374–88. Berlin, Heidelberg: Springer Berlin Heidelberg, 2005. http://dx.doi.org/10.1007/978-3-540-31987-0_26.
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Thibault, Louis, Peter Avitabile, Jason R. Foley, and Janet Wolfson. "Equivalent Reduced Model Technique Development for Nonlinear System Dynamic Response." In Topics in Nonlinear Dynamics, Volume 3, 95–127. New York, NY: Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4614-2416-1_9.
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Lee, Sang Yub, Jae Kyu Lee, Duck Keun Park, and Jae Jin Ko. "Equivalent Test Model of Wireless Optical Communication System for Automotive Environment." In Lecture Notes in Electrical Engineering, 341–48. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-662-47895-0_41.
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Gonzalez-Longatt, Francisco M., José Luis Rueda, C. A. Charalambous, and P. De Oliveira. "Estimation of Equivalent Model for Cluster of Induction Generator Based on PMU Measurements." In PowerFactory Applications for Power System Analysis, 473–89. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-12958-7_20.
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Das, Anamika, Ananyo Bhattacharya, and Pradip Kumar Sadhu. "Equivalent Two-Coil Model for a Four-Coil Wireless Power Transfer System." In Recent Advances in Power Electronics and Drives, 111–22. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-8586-9_11.
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Barrios-Gomez, Jose A., Francisco Sanchez, Francisco Gonzalez-Longatt, Gianfranco Claudio, Alberto Cavazos, Harold R. Chamorro, and Wilmar Martinez. "Data-Driven Fuzzy C-Means Equivalent Turbine-Governor for Power System Frequency Response." In Soft Computing for Data Analytics, Classification Model, and Control, 117–35. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-92026-5_7.
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Zhang, Weicun, and Qing Li. "Stable Weighted Multiple Model Adaptive Control of Continuous-Time Plant." In Virtual Equivalent System Approach for Stability Analysis of Model-based Control Systems, 111–27. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-5538-1_6.
Повний текст джерелаТези доповідей конференцій з теми "System Equivalent Model Mixing"
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Makhoul, Alain, Kamel Ghali, and Nesreen Ghaddar. "Ceiling-Mounted Fresh Air Personalized Ventilator System for Occupant-Controlled Microenvironment." In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-87565.
Повний текст джерелаАнотація:
The aim of this work is to develop an effective coaxial personalized ventilator nozzle as add-on to ceiling diffuser to localize the air conditioning and fresh air needs of occupants in a space. The ceiling diffusers supply the space with circulated conditioned return air while the personalized coaxial ventilators supply fresh air directly to the breathing zone of occupants. The coaxial nozzle minimizes air entrainment between the fresh air stream and the space contaminated air and allows the effective delivery of fresh air from a substantial distance with lower amounts than what is required by ASHRAE standards. A detailed 3D CFD model was developed and used to optimize the nozzles dimensions and outlet flow characteristics. The CFD model numerical findings were then validated against experimental data where flow field measurements involving the flow rate and air quality were taken. The proposed air delivery system (coaxial personalized ventilator and angled ceiling diffuser) has substantially reduced air conditioning system energy consumption (up to 28%) when it was compared with conventional overhead mixing systems. Meanwhile, it permitted to obtain equivalent thermal comfort conditions and achieve higher breathing air quality (45% ventilation effectiveness at 10 L/s.person fresh air flow rate) compared to conventional mixed air systems with the privilege of the occupant being able to control his own microclimate.
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Müller, Jens Satria, Finn Lückoff, Thomas Ludwig Kaiser, Christian Oliver Paschereit, and Kilian Oberleithner. "Modal Decomposition and Linear Modeling of Swirl Fluctuations in the Mixing Section of a Model Combustor Based on PIV Data." In ASME Turbo Expo 2021: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/gt2021-58832.
Повний текст джерелаАнотація:
Abstract In order to determine the flame transfer function of a combustion system only based on isothermal flow field data, three governing mechanisms have been identified which need to be modeled: swirl fluctuations, equivalence fluctuations and velocity fluctuations excited by planar acoustic waves. This study focuses on the generation and propagation of swirl fluctuations downstream of a radial swirl combustor under isothermal conditions. Swirl fluctuations are generated experimentally by imposing acoustic perturbations. Time-resolved longitudinal and crosswise PIV measurements are conducted inside the mixing tube and combustion chamber to quantify the evolution of the swirl fluctuations. The measured flow response is decomposed using spectral proper orthogonal decomposition to unravel the contributions of different dynamical modes. In addition a resolvent analysis is conducted based on the linearized Navier-Stokes equations to reveal the intrinsically most amplified flow structures. Both, the data-driven and analytic approach, show that inertial waves are indeed present in the flow response and an inherent flow instability downstream of the swirler, which confirms the recent theoretical work of Albayrak et al. (Journal of Fluid Mechanics, 879). However, the contribution of these inertial waves to the total swirl fluctuations turns out to be very small. This is suggested to be due to the very structured forcing at the swirler and the amplification of shear-driven modes which are expected to be much more influential for this type of swirler. Overall, this work confirms the presence of inertial waves in highly turbulent swirl combustors and evaluates its relevance for industry-related configurations. It further outlines a methodology to analyze and predict their characteristics based on mean fields only, which is applicable for complex geometries of industrial relevance.
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Saeed, Zeeshan, Christian Maria Firrone, and Teresa Maria Berruti. "Hybrid Numerical-Experimental Model Update Based on Correlation Approach for Turbine Components." In ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/gt2020-16308.
Повний текст джерелаАнотація:
Abstract Bladed-disks in turbo-machines experience high cycle fatigue failures due to high vibration amplitudes. Therefore, it is important to accurately predict their dynamic characteristics including the mechanical joints at blade-disk (root joint) or blade-blade (shroud) interfaces. These joints help in dampening the vibration amplitudes. Before the experimental identification of these joints, it is of paramount importance to accurately measure the interface degrees-of-freedom (DoF). However, they are largely inaccessible for the measurements. For this reason, expansion techniques are used in order to update the single components before their coupling. But the expansion can be affected adversely if the measurements are not properly correlated with the updated model or if they have significant errors. Therefore, a frequency domain expansion method called System Equivalent Model Mixing (SEMM) is used to expand a limited set of measurements to a larger set of numerical DoF. Different measured models — termed the overlay models — are taken from an impact testing campaign of a blade and a disk and coupled to the numerical model according to the SEMM. The expanded models — termed the hybrid models — are then correlated with the validation channels in a round-robin way by means of Frequency Response Assurance Criteria (FRAC). The global correlations depict whether or not a measurement and the respective expansion is properly correlated. By this approach, the least correlated channels can be done away with from the measurements to have a better updated hybrid model. The method is tested on both the structures (the blade and the disk) and it is successfully shown that removing the uncorrelated channels does improve the quality of the hybrid models.
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Javadi, A., and D. Bastani. "Estimation of Mass Transfer During Drop Formation: New Flow Expansion Model." In ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-62443.
Повний текст джерелаАнотація:
Although there is extensive experimental, theoretical and numerical research on dynamics of drop formation in liquid-liquid systems, the evaluation of mass transfer during drop formation is rather complex and there has been little research on that. The various mathematical models developed for this problem are generally based on a solution of the diffusion equation without any allowance for circulation within the drop. This is the main reason for the poor prediction of these models in many cases for which internal convection has an important effect on mass transfer rate. In this paper an attempt was made to define a parameter related to the extent of the convective mixing within the growing drop. For this purpose it is assumed that the entrance of the dispersed flow into the growing drop from the nozzle is analogous to the entrance of the flow from a smaller channel to a larger one (the expanding drops). This transfer mechanism presented in this paper has been dubbed “flow expansion.” A global time-dependent Reynolds number was defined based on the equivalent diameter of growing drop as a length scale and also on a velocity scale, which is obtained using this flow expansion assumption. This time dependent Reynolds number of growing drop (Regd) has an important role on the mass transfer coefficient. The results of the model where predicting the effects of the nozzle diameter and dispersed phase flow rate on the mass transfer behavior showed good agreement with experimental data. This comparison demonstrates an improvement on famous models such as surface stretch and fresh surface elements for evaluation of mass transfer during drop formation.
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King, Phil T., T. B. Mat Lazim, Gordon E. Andrews, Mohamed M. Pourkashanian, and Andy C. McIntosh. "Internal Gas Analysis and CFD Predictions of Double Contra-Rotating Axial Swirlers With Fuel Injection From Between the Two Outlets." In ASME Turbo Expo 2012: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/gt2012-69303.
Повний текст джерелаАнотація:
A double contra-rotating axial swirler was investigated at 0.38 equivalence ratio and 600K inlet temperature at 1 bar, both experimentally and using CFD. Natural gas fuel was injected from between the two contra-rotating flows. The experimental results showed that whilst the NOx emissions were relatively high, the system has excellent flame stability characteristics meaning the flame could be maintained at very low fuel-air ratios, down to an equivalence ratio of around 0.28. CFD predictions were carried out using the equilibrium pdf combustion model alongside the partially premixed combustion model using default model constants, and the NOx model was applied as a post-processing application. The results showed that whilst the location and shape of the flame and the combustor fuel-air distribution could not be precisely captured, the peak temperature, CO, UHC and NOx levels were correctly predicted. The influence of the turbulent Schmidt number, Sct, was therefore investigated in an attempt to improve the predictions. Lower values offered an improvement in the fuel-air mixing predictions, but not in the combustion predictions, where the peak flame temperature could only be predicted correctly when using the default value of Sct = 0.85. This indicates that the use of a universal turbulent Schmidt number for both the fuel-air mixing and combustion models may not be suitable for the present swirler and combustor configuration, therefore future work will look to use a separate value of Sct for the mixture fraction than for the pdf combustion models.
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Weigand, Peter, Wolfgang Meier, Xuru Duan, and Manfred Aigner. "Laser Based Investigations of Thermo-Acoustic Instabilities in a Lean Premixed Gas Turbine Model Combustor." In ASME Turbo Expo 2006: Power for Land, Sea, and Air. ASMEDC, 2006. http://dx.doi.org/10.1115/gt2006-90300.
Повний текст джерелаАнотація:
Non-intrusive laser-based and optical measurements were performed in a gas turbine model combustor with a lean premixed swirl-stabilized CH4-air flame at atmospheric pressure. The main objective was to gain spatially and temporally resolved experimental data to enable the validation of numerical CFD-results of oscillating flames. The investigated flame was operated at 25 kW and φ = 0.70 and exhibited self-excited oscillations of more than 135 dB at about 300 Hz. The applied measurement techniques were 3-D LDV for velocity measurements, OH* chemiluminescence yielding information about the heat release, and point-wise laser Raman scattering for the determination of joint PDFs of the major species concentrations, temperature, and mixture fraction. Each of these techniques was applied with phase resolution with respect to the periodic fluctuation of the pressure in the combustion chamber that was measured with a microphone probe. The measurements finally revealed that the mixing of fuel and air in this technical premixing system was strongly affected by the pressure fluctuations leading to changes in equivalence ratio during an oscillation cycle which in turn induced the pressure fluctuations.
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Gowda Kodebyle Raju, Nandini, Adam Dempsey, and Scott Curran. "Analysis of Engine Air Handling Systems for Light-Duty Compression Ignition Engines Using 1-D Cycle Simulation: Achieving High Dilution Levels for Advanced Combustion." In ASME 2016 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/icef2016-9459.
Повний текст джерелаАнотація:
Previous research studies have shown that low temperature combustion (LTC) strategies are capable of achieving very low NOx and soot emissions while maintaining high thermal efficiency. To achieve LTC, there has to be sufficient mixing time between the fuel and air in a dilute, yet overall lean, environment. Dilution with a combination of fresh air and exhaust gas recirculation (EGR) is typically used to achieve longer mixing times and reduce the peak combustion temperatures. However, there are challenges associated with today’s engine air handling systems’ ability to move large combinations of EGR and air simultaneously. As the EGR demand is increased to reduce NOx emissions or retard combustion phasing, the global equivalence ratio tends to increase because of the boosting systems’ limited ability to supply fresh air. In this study, a one-dimensional engine modeling approach was used to analyze the behavior of a production light duty diesel engine equipped with a variable geometry turbocharger and a high-pressure loop EGR system under LTC conditions. The model is used to predict the global equivalence ratio as a function of the EGR level at a variety of operating conditions. The EGR level was varied from 0 to 50% at speeds ranging from 1,500 to 2,500 rpm and loads from 2 to 10 bar brake mean effective pressure. The objective of this study is to evaluate the air handling system’s capability of driving high amounts of EGR and air simultaneously for light duty engines to successfully achieve LTC operation over a large portion of the operating space. The results of the simulations show that at light loads, large amounts of EGR can be used while maintaining globally lean operation. However, as the engine load increases, a globally stoichiometric condition is reached relatively quickly, and high engine loads with greater than 30% EGR and overall lean conditions were achievable.
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Abou-Taouk, Abdallah, Suresh Sadasivuni, Daniel Lörstad, and Lars-Erik Eriksson. "Evaluation of Global Mechanisms for LES Analysis of SGT-100 DLE Combustion System." In ASME Turbo Expo 2013: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gt2013-95454.
Повний текст джерелаАнотація:
This paper presents the results of Computational Fluid Dynamics (CFD) analyses obtained for the experimental version of the SGT-100 Dry Low Emission (DLE) gas turbine burner provided by Siemens Industrial Turbomachinery Ltd (SIT). A testing and measurement campaign for this burner was previously carried out at the DLR Institute of Combustion Technology, Stuttgart, Germany, for various operating pressure conditions. The present work shows the successful validation of the CFD model in terms of time-averaged temperature and velocity data within measurement errors at an operating pressure of 3 bar. Several well known global mechanisms are tested in this work, namely the Westbrook Dryer 2-step (WD) scheme, the Jones and Lindstedt 4-step (JL4) scheme, the Meredith et al. 3-step (M3) scheme and a recently developed in-house 4-step scheme (M4) for methane-air mixtures. The M4 scheme is optimized by matching the detailed GRI-Mech 3.0 mechanism in terms of 1D laminar flame speed, using the CHEMKIN software for a wide range of pressures (1 to 6 bar), unburned gas temperatures (295 to 650 K) and equivalence ratios range (0.4 to 1.6). CFD simulations are performed using the Eddy Dissipation Model (EDM)/Finite Rate Chemistry (FRC) non-premixed turbulence chemistry interaction model. Both steady-state Reynolds Averaged Navier Stokes (RANS) and hybrid Unsteady Reynolds Averaged Navier Stokes /Large Eddy Simulation (URANS/LES) turbulence models are used. The LES Wall Adaptive Large Eddy-Viscosity (WALE) model with finite rate chemistry is also tested for validation. Velocity profiles, flame temperatures and major species are compared with experiments for different global reaction mechanisms used with different turbulence models. A reasonable agreement is found with the M4 global reaction mechanism in predicting mixing, temperatures and major species. RANS simulations are observed to underpredict the temperature profiles downstream and overpredict in the upstream region, while the velocity profiles are found to be in close agreement with experiments. The SAS-SST turbulence model predicts the velocity profiles in good agreement with experimental data and slightly better than the RANS model. Both the transient simulations slightly overpredict the temperature profiles. The LES-WALE model gives too high and unrealistic temperatures.
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Liu, Dongdong, Xiang Luo, and Zhi Tao. "A Computational Investigation of Hot Gas Ingress Through the Rim Seal of a Counter-Rotating Turbine Cavity With Annulus." In ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-42944.
Повний текст джерелаАнотація:
The hot gas ingestion through rim seals of counter-rotating turbine disks with annulus flow is investigated by numerical simulation in this paper. Three models were calculated in this paper, counter-rotating turbine cavity with annulus and radial sealing inlet, the same geometric configuration but in rotor-stator system and the counter-rotating turbine cavity without annulus. The axial Reynolds number of annulus was set at 5.99×105 and rotating Reynolds number was set at 2.35×105, the non-dimensional sealing flow rate was changed from 279 to 1116. The results of simulation indicated that counter-rotating cavity with radial inlet was found to have a much higher sealing efficiency than the stator-rotor cavity at the equivalent condition. The flow path of ingestion gas was considered to be the cause for this. For the difference of flow structure of cavities, the annulus air is ingested the middle of cavity for counter-rotating cavity rather than flowed towards the static wall for rotor-stator cavity. Therefore, the sealing efficiency for counter-rotating cavity is high in both of the walls but low inside the cavity. In addition, preswirl of sealing air was found to affect the sealing efficiency by changing the flow inside cavity and making the early mixing of sealing air and ingestion gas.
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Krawciw, Jason, Damian Martin, and Paul Denman. "Measurement and Prediction of Adiabatic Film Effectiveness of Combustor Representative Effusion Arrays." In ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-43210.
Повний текст джерелаАнотація:
Thermal protection of gas turbine combustors relies heavily upon the delivery of a carefully managed film of coolant air to the hot-side of the combustor liner. Furthermore, improvements in engine sfc and the trend to ever more aggressive engine cycles means greater emphasis is being placed upon more efficient use of the proportion of combustion system air made available for cooling. As a result, there is a requirement to better understand the development of cooling films deposited onto the hot-side of the liner through complex effusion arrays. This study, therefore, is concerned with the prediction and measurement of adiabatic film effectiveness of a number of engine-representative designs. A RANS based CFD approach is used to predict film effectiveness in which computational cost is minimised by solving first for a single coolant passage to provide high fidelity, near-exit boundary conditions to the effusion arrays. Equivalent measurements are made for each test case using a Pressure Sensitive Paint (PSP) technique in which the oxygen-quenched fluorescence properties of the paint are employed together with a Nitrogen gas cooling simulant to determine adiabatic film effectiveness. This study demonstrates that whist the model under-predicts the mixing of the coolant with the main-stream flow, and hence the film development over the surface, the approach works well at quantifying the relative performance of each design.
Звіти організацій з теми "System Equivalent Model Mixing"
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Jablonowski, Christiane. Final Report. Evaluating the Climate Sensitivity of Dissipative Subgrid-Scale Mixing Processes and Variable Resolution in NCAR's Community Earth System Model. Office of Scientific and Technical Information (OSTI), December 2015. http://dx.doi.org/10.2172/1232606.
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Drzymala, J., and T. D. Wheelock. Development of a gas-promoted oil agglomeration process: Air-promoted oil agglomeration of moderately hydrophobic coals. 2: Effect of air dosage in a model mixing system. Office of Scientific and Technical Information (OSTI), July 1996. http://dx.doi.org/10.2172/257322.
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Hefetz, Abraham, and Justin O. Schmidt. Use of Bee-Borne Attractants for Pollination of Nonrewarding Flowers: Model System of Male-Sterile Tomato Flowers. United States Department of Agriculture, October 2003. http://dx.doi.org/10.32747/2003.7586462.bard.
Повний текст джерелаАнотація:
The use of bee natural product for enhancing pollination is especially valuable in problematic crops that are generally avoided by bees. In the present research we attempted to enhance bee visitation to Male Sterile (M-S) tomato flowers generally used in the production of hybrid seeds. These flowers that lack both pollen and nectar are unattractive to bees that learn rapidly to avoid them. The specific objects were to elucidate the chemical composition of the exocrine products of two bumble bee species the North American Bombus impatiens and the Israeli B. terrestris. Of these, to isolate and identify a bee attractant which when sprayed on M-S tomato flowers will enhance bee visitation, and to provide a procedure of the pheromone application regime. During the research we realized that our knowledge of B. impatiens is too little and we narrowed the objective to learning the basic social behavior of the bees and the pattern of foraging in a flight chamber and how it is affected by biogenic amines. Colonies of B. impatiens are characterized by a high number of workers and a relatively small number of queens. Size differences between queens and workers are pronounced and the queen seems to have full control over egg laying. Only about 9% of the workers in mature colonies had mature oocytes, and there were no signs of a "competition phase" as we know in B. terrestris. Queens and workers differ in their exocrine bouquet. Queen's Dufour's gland possesses a series of linear, saturated and unsaturated hydrocarbons whereas that of workers contains in addition a series of wax-type esters. Bees were trained to either visit or avoid artificially scented electronic flowers in a flight chamber. Since bee also learned to avoid scented non-rewarding flowers we attempted to interfere with this learning. We tested the effect of octopamine, a biogenic amine affecting bee behavior, on the choice behavior of free-flying bumblebees. Our results show that octopamine had no significant effect on the bees' equilibrium choice or on the overall rate of the behavioral change in response to the change in reward. Rather, octopamine significantly affected the time interval between the change in reward status and the initiation of behavioral change in the bee. In B. terrestris we studied the foraging pattern of the bees on tomato flowers in a semi commercial greenhouse in Yad Mordechai. Bee learned very quickly to avoid the non- rewarding M-S flowers, irrespective of their arrangement in the plot, i.e., their mixing with normal, pollen bearing flowers. However, bees seem to "forget" this information during the night since the foraging pattern repeats itself the next morning. Several exocrine products were tested as visitation enhancers. Among these, tarsal gland extracts are the most attractive. The compounds identified in the tarsal gland extract are mostly linear saturated hydrocarbons with small amounts of unsaturated ones. Application was performed every second day on leaves in selected inflorescences. Bee visitation increased significantly in the treated inflorescences as compared to the control, solvent treated. Treatment of the anthers cone was more effective than on the flower petals or the surrounding leaves. Methanol proved to be a non-flower-destructive solvent. We have shown that bumble bees (B. terrestris) can be manipulated by bee-borne attractants to visit non-rewarding flowers. We have further demonstrated that the bees learning ability can be manipulated by applying exogenously octopamine. Both methods can be additively applied in enhancing pollination of desired crops. Such manipulation will be especially useful in tomato cultivation for hybrid seed production.
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Burroughs, Jedadiah, Jason Weiss, and John Haddock. Influence of high volumes of silica fume on the rheological behavior of oil well cement pastes. Engineer Research and Development Center (U.S.), July 2021. http://dx.doi.org/10.21079/11681/41288.
Повний текст джерелаАнотація:
Specialized classes of concrete, such as ultra-high-performance concrete, use volumes of silica fume in concrete that are higher than those in conventional concrete, resulting in increased water demand and mixing difficulty. This study considered the effects of eight different silica fumes in three dosages (10%, 20%, 30%) with three w/b (0.20, 0.30, 0.45) on rheological behavior as characterized by the Herschel-Bulkley model. Results indicated that the specific source of silica fume used, in addition to dosage and w/b, had a significant effect on the rheological behavior. As such, all silica fumes cannot be treated as equivalent or be directly substituted one for another without modification of the mixture proportion. The rheology of cement pastes is significantly affected by the physical properties of silica fume more so than any chemical effects.
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Castro, Rubén, Leonardo González, Ignacio Schiappacasse, and Juan Tapia. The Impact of Covid-19 on Pensions due to Early Withdrawals of Pension Savings. Inter-American Development Bank, November 2022. http://dx.doi.org/10.18235/0004517.
Повний текст джерелаАнотація:
The Chilean pension system was hit hard during 2020-2021 by the withdrawal of 25 per cent of the individual pensions funds accumulated by 2019, an amount equivalent to 20 per cent of Chiles GDP. We estimate here the impact of those withdrawals on new pension allowances, using a combination of official data sets and the IDB model for the actuarial projection of pensions, including its heterogeneity matrix, to simulate the distribution of pension impacts. The withdrawal impact decreases in new retirees of future years until disappearing around the year 2065. We estimate respective impacts of about 31 percent and 37 percent for males and females new self-financed pensions around the year 2022, which goes to about 56 percent among the third of the affiliates with the lowest savings. However, we found that the recent increase in non-contributory pensions more than counteracted this impact for roughly 90 percent of 2022 new retirees. Regarding labor markets shocks, we found only a moderate role for them in the long-term evolution of the pension system, as we also found to be the case of seven Caribbean countries (Cuba, Haiti, Dominican Republic, Jamaica, Trinidad and Tobago, Bahamas and Barbados). As an overall conclusion, we recommend studying contribution rates, because low-salary workers attain a substantial replacement rate with just the non-contributory pension, which casts doubt on whether a mandatory contribution is appropriate for them.
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Moran, Nava, Richard Crain, and Wolf-Dieter Reiter. Regulation by Light of Plant Potassium Uptake through K Channels: Biochemical, Physiological and Biophysical Study. United States Department of Agriculture, September 1995. http://dx.doi.org/10.32747/1995.7571356.bard.
Повний текст джерелаАнотація:
The swelling of plant motor cells is regulated by various signals with almost unknown mediators. One of the obligatory steps in the signaling cascade is the activation of K+-influx channels -K+ channels activated by hyperpolarization (KH channels). We thus explored the regulation of these channels in our model system, motor cell protoplasts from Samanea saman, using patch-clamp in the "whole cell" configuration. (a) The most novel finding was that the activity of KH channels in situ varied with the time of the day, in positive correlation with cell swelling: in Extensor cells KH channels were active in the earlier part of the day, while in Flexor cells only during the later part of the day; (b) High internal pH promoted the activity of these channels in Extensor cells, opposite to the behavior of the equivalent channels in guard cells, but in conformity with the predicted behavior of the putative KH channel, cloned from S. saman recently; (c) HIgh external K+ concentration increased (KH channel currents in Flexor cells. BL depolarized the Flexor cells, as detected in cell-attached patch-clamp recording, using KD channels (the K+-efflux channels) as "voltage-sensing devices". Subsequent Red-Light (RL) pulse followed by Darkness, hyperpolarized the cell. We attribute these changes to the inhibition of the H+-pump by BL and its reactivation by RL, as they were abolished by an H+-pump inhibitor. BL increased also the activity KD channels, in a voltage-independent manner - in all probability by an independent signaling pathway. Blue-Light (BL), which stimulates shrinking of Flexor cells, evoked the IP3 signaling cascade (detected directly by IP3 binding assay), known to mobilize cytosolic Ca2+. Nevertheless, cytosolic Ca2+ . did not activate the KD channel in excised, inside-out patches. In this study we established a close functional similarity of the KD channels between Flexor and Extensior cells. Thus the differences in their responses must stem from different links to signaling in both cell types.
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Rahai, Hamid, and Jeremy Bonifacio. Numerical Investigations of Virus Transport Aboard a Commuter Bus. Mineta Transportation Institute, April 2021. http://dx.doi.org/10.31979/mti.2021.2048.
Повний текст джерелаАнотація:
The authors performed unsteady numerical simulations of virus/particle transport released from a hypothetical passenger aboard a commuter bus. The bus model was sized according to a typical city bus used to transport passengers within the city of Long Beach in California. The simulations were performed for the bus in transit and when the bus was at a bus stop opening the middle doors for 30 seconds for passenger boarding and drop off. The infected passenger was sitting in an aisle seat in the middle of the bus, releasing 1267 particles (viruses)/min. The bus ventilation system released air from two linear slots in the ceiling at 2097 cubic feet per minute (CFM) and the air was exhausted at the back of the bus. Results indicated high exposure for passengers sitting behind the infectious during the bus transit. With air exchange outside during the bus stop, particles were spread to seats in front of the infectious passenger, thus increasing the risk of infection for the passengers sitting in front of the infectious person. With higher exposure time, the risk of infection is increased. One of the most important factors in assessing infection risk of respiratory diseases is the spatial distribution of the airborne pathogens. The deposition of the particles/viruses within the human respiratory system depends on the size, shape, and weight of the virus, the morphology of the respiratory tract, as well as the subject’s breathing pattern. For the current investigation, the viruses are modeled as solid particles of fixed size. While the results provide details of particles transport within a bus along with the probable risk of infection for a short duration, however, these results should be taken as preliminary as there are other significant factors such as the virus’s survival rate, the size distribution of the virus, and the space ventilation rate and mixing that contribute to the risk of infection and have not been taken into account in this investigation.
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Snyder, Victor A., Dani Or, Amos Hadas, and S. Assouline. Characterization of Post-Tillage Soil Fragmentation and Rejoining Affecting Soil Pore Space Evolution and Transport Properties. United States Department of Agriculture, April 2002. http://dx.doi.org/10.32747/2002.7580670.bard.
Повний текст джерелаАнотація:
Tillage modifies soil structure, altering conditions for plant growth and transport processes through the soil. However, the resulting loose structure is unstable and susceptible to collapse due to aggregate fragmentation during wetting and drying cycles, and coalescense of moist aggregates by internal capillary forces and external compactive stresses. Presently, limited understanding of these complex processes often leads to consideration of the soil plow layer as a static porous medium. With the purpose of filling some of this knowledge gap, the objectives of this Project were to: 1) Identify and quantify the major factors causing breakdown of primary soil fragments produced by tillage into smaller secondary fragments; 2) Identify and quantify the. physical processes involved in the coalescence of primary and secondary fragments and surfaces of weakness; 3) Measure temporal changes in pore-size distributions and hydraulic properties of reconstructed aggregate beds as a function of specified initial conditions and wetting/drying events; and 4) Construct a process-based model of post-tillage changes in soil structural and hydraulic properties of the plow layer and validate it against field experiments. A dynamic theory of capillary-driven plastic deformation of adjoining aggregates was developed, where instantaneous rate of change in geometry of aggregates and inter-aggregate pores was related to current geometry of the solid-gas-liquid system and measured soil rheological functions. The theory and supporting data showed that consolidation of aggregate beds is largely an event-driven process, restricted to a fairly narrow range of soil water contents where capillary suction is great enough to generate coalescence but where soil mechanical strength is still low enough to allow plastic deforn1ation of aggregates. The theory was also used to explain effects of transient external loading on compaction of aggregate beds. A stochastic forInalism was developed for modeling soil pore space evolution, based on the Fokker Planck equation (FPE). Analytical solutions for the FPE were developed, with parameters which can be measured empirically or related to the mechanistic aggregate deformation model. Pre-existing results from field experiments were used to illustrate how the FPE formalism can be applied to field data. Fragmentation of soil clods after tillage was observed to be an event-driven (as opposed to continuous) process that occurred only during wetting, and only as clods approached the saturation point. The major mechanism of fragmentation of large aggregates seemed to be differential soil swelling behind the wetting front. Aggregate "explosion" due to air entrapment seemed limited to small aggregates wetted simultaneously over their entire surface. Breakdown of large aggregates from 11 clay soils during successive wetting and drying cycles produced fragment size distributions which differed primarily by a scale factor l (essentially equivalent to the Van Bavel mean weight diameter), so that evolution of fragment size distributions could be modeled in terms of changes in l. For a given number of wetting and drying cycles, l decreased systematically with increasing plasticity index. When air-dry soil clods were slightly weakened by a single wetting event, and then allowed to "age" for six weeks at constant high water content, drop-shatter resistance in aged relative to non-aged clods was found to increase in proportion to plasticity index. This seemed consistent with the rheological model, which predicts faster plastic coalescence around small voids and sharp cracks (with resulting soil strengthening) in soils with low resistance to plastic yield and flow. A new theory of crack growth in "idealized" elastoplastic materials was formulated, with potential application to soil fracture phenomena. The theory was preliminarily (and successfully) tested using carbon steel, a ductile material which closely approximates ideal elastoplastic behavior, and for which the necessary fracture data existed in the literature.