Relevant bibliographies by topics / Mode field spatial distribution

Academic literature on the topic 'Mode field spatial distribution'

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Published: 30 May 2022
Last updated: 31 May 2022

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Journal articles on the topic "Mode field spatial distribution"

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RAGHU KANTH, S. T. G. "INTRINSIC MODE FUNCTIONS OF EARTHQUAKE SLIP DISTRIBUTION." Advances in Adaptive Data Analysis 02, no. 02 (April 2010): 193–215. http://dx.doi.org/10.1142/s1793536910000458.

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In this paper, empirical mode decomposition technique is used to analyze the spatial slip distribution of five past earthquakes. It is shown that the finite fault slip models exhibit five empirical modes of oscillation. The last intrinsic mode is positive and characterizes the non-stationary mean of the slip distribution. This helps in splitting the spatial variability of slip into trend and the remaining modes sum as the fluctuation in the data. The fluctuation component indicates that it can be modeled as an anisotropic random field. Important parameters of this random field have been estimated. The effect of these modes on ground motion is presented by simulating both acceleration and displacement time histories.
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Ledneva, H. P., A. V. Korzhov, L. A. Kotomtseva, and L. G. Astafyeva. "The effect of spatial field distribution on two-mode lasing in a spherical microparticle." Optics and Spectroscopy 94, no. 3 (March 2003): 476–80. http://dx.doi.org/10.1134/1.1563697.

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Sangeetha, S., and S. T. G. Raghukanth. "A Stochastic source model for the 2015 Mw 7.9 Gorkha, Nepal, Earthquake using Multi-Dimensional Ensemble Empirical Mode Decomposition technique." MATEC Web of Conferences 148 (2018): 08004. http://dx.doi.org/10.1051/matecconf/201814808004.

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The present study aims at developing a new strategy to model the spatial variability of slip on the rupture plane using multi-dimensional ensemble empirical mode decomposition (MEEMD) technique. Here, the earthquake slip distribution is split into finite number of empirical modes of oscillation called the intrinsic mode functions (IMFs). This help in identifying the fluctuation component and trend in the slip data. The trend is positive and characterizes the nonstationary mean of the slip distribution. The fluctuation component can be modelled as a stationary random field using an exponential power spectral density function. The trend can be modeled as an elliptic patch. This new technique is demonstrated for the slip distribution of the recent Nepal Earthquake, 2015. It is observed that the new model can be used to simulate the spatial complexity of slip distribution of any earthquake.
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Kuo, C.-W., M. Crawley, J. Cluts, and M. Samimy. "Near-field pressure waveform analysis of an excited Mach 0.9 jet." International Journal of Aeroacoustics 17, no. 1-2 (February 24, 2018): 114–34. http://dx.doi.org/10.1177/1475472x17743631.

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This work explores the effects of axisymmetric, helical, and flapping mode perturbations over a range of Strouhal numbers on the near-field pressure of an axisymmetric Mach 0.9 jet with a Reynolds number of 6.2 × 105. Excitation is generated by eight localized arc filament plasma actuators uniformly distributed around the nozzle exit. The excitation of jet shear layer instabilities resulted in large-scale structures. The signature of these structures in the irrotational near field appears as high-amplitude hydrodynamic pressure fluctuations with wavepacket-like growth, saturation, and decay. The excitation Strouhal number and, perhaps more importantly, the azimuthal mode, are seen to strongly affect the spatial evolution of the wavepacket in both axial and radial directions. The dominant excitation Strouhal number is around 0.3, and the most significant effect on the jet statistical properties (such as distributions of velocity and pressure) occurs further downstream for the flapping mode in comparison to the axisymmetric mode. Dynamic mode decomposition is performed to further describe the modal behavior and evolution of hydrodynamic pressure fluctuations. The pressure response in the near field of jet plumes in flapping mode excitation is shown to exhibit two azimuthal mode behaviors: axisymmetric and flapping. An empirical model of hydrodynamic pressure distribution is established with normalized axial and radial profiles. The amplitude and distribution of the hydrodynamic pressure component are well depicted by the empirical reconstruction.
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Liu, Yongkai, Jianli Wang, Lie Ma, Shijie Gao, Chenzi Guo, Kainan Yao, and Lei Sheng. "The Effect of Spatial Mode Distribution on Coupling Efficiency of Single-Mode Fiber: Theoretical Analysis and Experimental Verification." Applied Sciences 9, no. 16 (August 11, 2019): 3296. http://dx.doi.org/10.3390/app9163296.

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In this study, Zernike polynomials and optical fiber field theory are applied to build a mathematical model of coupling efficiency (CE) and spatial mode of aberrations. The theory built in this paper can be used to quickly calculate the CE affected by a single aberration as well as the aberrations caused by atmospheric turbulence. The aberrations are classified based on Zernike polynomials and the effects of aberrations on CE of different types and different spatial frequencies are analyzed. The influence of the effects of AO system residual errors is also analyzed. Adaptive optics (AO) equipment is applied to build a system on which the proposed theory was tested; the experimental results validate the theoretical analysis.
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Casper, Katya M., Justin L. Wagner, Steven J. Beresh, Russell W. Spillers, John F. Henfling, and Lawrence J. Dechant. "Spatial distribution of pressure resonance in compressible cavity flow." Journal of Fluid Mechanics 848 (June 11, 2018): 660–75. http://dx.doi.org/10.1017/jfm.2018.346.

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The development of the unsteady pressure field on the floor of a rectangular cavity was studied at Mach 0.9 using high-frequency pressure-sensitive paint. Power spectral amplitudes at each cavity resonance exhibit a spatial distribution with a streamwise-oscillatory pattern; additional maxima and minima appear as the mode number is increased. This spatial distribution also appears in the propagation velocity of modal pressure disturbances. This behaviour was tied to the superposition of a downstream-propagating shear-layer disturbance and an upstream-propagating acoustic wave of different amplitudes and convection velocities, consistent with the classical Rossiter model. The summation of these waves generates a net downstream-travelling wave whose amplitude and phase velocity are modulated by a fixed envelope within the cavity. This travelling-wave interpretation of the Rossiter model correctly predicts the instantaneous modal pressure behaviour in the cavity. Subtle spanwise variations in the modal pressure behaviour were also observed, which could be attributed to a shift in the resonance pattern as a result of spillage effects at the edges of the finite-width cavity.
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Durán, O., V. Schwämmle, P. G. Lind, and H. J. Herrmann. "Size distribution and structure of Barchan dune fields." Nonlinear Processes in Geophysics 18, no. 4 (July 13, 2011): 455–67. http://dx.doi.org/10.5194/npg-18-455-2011.

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Abstract. Barchans are isolated mobile dunes often organized in large dune fields. Dune fields seem to present a characteristic dune size and spacing, which suggests a cooperative behavior based on dune interaction. In Duran et al. (2009), we propose that the redistribution of sand by collisions between dunes is a key element for the stability and size selection of barchan dune fields. This approach was based on a mean-field model ignoring the spatial distribution of dune fields. Here, we present a simplified dune field model that includes the spatial evolution of individual dunes as well as their interaction through sand exchange and binary collisions. As a result, the dune field evolves towards a steady state that depends on the boundary conditions. Comparing our results with measurements of Moroccan dune fields, we find that the simulated fields have the same dune size distribution as in real fields but fail to reproduce their homogeneity along the wind direction.
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Козырева, Ольга, Olga Kozyreva, Вячеслав Пилипенко, Vyacheslav Pilipenko, Марк Энгебретсон, Mark Engebretson, Дмитрий Климушкин, Dmitriy Klimushkin, Павел Магер, and Pavel Mager. "Correspondence between the ULF wave power spatial distribution and auroral oval boundaries." Solar-Terrestrial Physics 2, no. 2 (August 10, 2016): 46–65. http://dx.doi.org/10.12737/20999.

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The world-wide spatial distribution of the wave power in the Pc5 band during magnetic storms has been compared with auroral oval boundaries. The poleward and equatorward auroral oval boundaries are estimated using either the British Antarctic Survey database containing IMAGE satellite UV observations of the aurora or the OVATION model based on the DMSP particle data. The “epicenter” of the spectral power of broadband Pc5 fluctuations during the storm growth phase is mapped inside the auroral oval. During the storm recovery phase, the spectral power of narrowband Pc5 waves, both in the dawn and dusk sectors, is mapped inside the auroral oval or around its equatorward boundary. This observational result confirms previously reported effects: the spatial/temporal variations of the Pc5 wave power in the morning/pre-noon sector are closely related to the dynamics of the auroral electrojet and magnetospheric field-aligned currents. At the same time, narrowband Pc5 waves demonstrate typical resonant features in the amplitude-phase latitudinal structure. Thus, the location of the auroral oval or its equatorward boundary is the preferred latitude for magnetospheric field-line Alfven resonator excitation. This effect is not taken into account by modern theories of ULF Pc5 waves, but it could be significant for the development of more adequate models.
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Dubrovin, V. F. "The field radiated by a single-mode optical waveguide excited by a field with a complex amplitude-phase spatial distribution." Journal of Communications Technology and Electronics 57, no. 12 (December 2012): 1249–53. http://dx.doi.org/10.1134/s1064226912110034.

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Wei, Shusheng, and Wusong Wen. "Antenna Current Calculation Based on Equivalent Transmission Line Model." Micromachines 13, no. 5 (April 30, 2022): 714. http://dx.doi.org/10.3390/mi13050714.

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This paper provides a new way for spatial current/field profiles for frequency-selective surface analytical approximation. It confirms that the per unit length radiation resistance of an equivalent transmission line model for line antenna has little influence on the normalized current distribution. The two-wire equivalent transmission line model (typically used for transmitting line antenna) is applied to the receiving line antenna. In this case, the corresponding incident field is decomposed into odd and even mode for asymmetric distribution. A one-wire equivalent transmission line model is then introduced for any antenna composed of relative narrow strips. The incident field does not need to be decomposed. According to the simulation, the transmission line loss has little influence on the current distribution.
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Dissertations / Theses on the topic "Mode field spatial distribution"

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Odarenko, E. N., Y. V. Sashkova, and A. A. Shmat’ko. "Localized field enhancement in slow-wave modes of modified Bragg waveguide." Thesis, IEEE, 2017. https://openarchive.nure.ua/handle/document/18123.

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Modified scheme of Bragg reflection waveguide with additional layers between the hollow core and cladding is considered. Dispersion diagrams are calculated on the base of dispersion equations solutions for ordinary and modified Bragg waveguides. Slow-wave regimes are considered for both kinds of structure. Electric field spatial distributions for localized slowwave modes of Bragg reflection waveguide are obtained. It is shown that modified scheme of Bragg waveguide provides the enhanced localization of the surface modes field in the hollow core. Therefore modified Bragg waveguide is the promising electrodynamic system not only for laser-driven accelerators but also for the vacuum electron devices where usual slow-wave structures are unconvenient.
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Sashkova, Y. V., and E. N. Odarenko. "The Effect of Additional Layers Parameters on the Modifided Bragg Waveguide Characteristics." Thesis, IEEE, 2017. https://openarchive.nure.ua/handle/document/18112.

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Bragg waveguide with additional layers between hollow core and periodic cladding is considered. On the base of dispersion equation solutions dispersion diagrams are obtained. The transversal spatial distributions of the electric field intensity are shown. The characteristics of Bragg waveguide respect to additional layer thickness and permittivity are considered. It is shown that increase of additional layers thickness results in increase of slow-waves number. Also field intensity decay in channel is reduced. Number of slow-waves increases respect to additional layers permittivity too. But distribution of the electric field intensity in the channel changes insignificantly. So one can tune additional layers parameters to get expected Bragg waveguide characteristics.
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Haag, Christian. "Temporal and spatial wind field distribution in Delaware Bay." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 9.11 Mb., 62 p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:1430767.

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Thesis (M.E.E.)--University of Delaware, 2006.
Principal faculty advisors: Kenneth E. Barner, Dept. of Electrical and Computer Engineering; and Mohsen Badiey, Dept. of Marine and Earth Studies. Includes bibliographical references.
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Getachew, T. (Tibebu). "Spatial-temporal structure and distribution of the solar photospheric magnetic field." Doctoral thesis, Oulun yliopisto, 2019. http://urn.fi/urn:isbn:9789526224367.

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Abstract I have made a detailed study of the fundamental properties of the solar photospheric magnetic field, which helps in better understanding the Sun’s radiative and particle outputs that affect the Earth’s near-space environment, as well as the entire heliosphere. Photospheric magnetic field is an essential parameter for space weather and space climate. The photospheric magnetic field includes a wide range of large-scale and small-scale structures, but the contribution of weak, small-scale fields to the total flux on the solar surface is dominant. This thesis discusses the spatial-temporal structure and long-term evolution of the solar photospheric magnetic field. Particularly, the thesis presents, for the first time, the spatial distribution of the asymmetry of weak field values and its evolution in solar cycles 21–24. I found that the asymmetry (also called shift) of the distribution of positive and negative weak-field values is a real physical phenomenon. I also found that the shifts are most effectively produced at the supergranulation scale. I studied the asymmetry of the distribution of weak field values separately in the two solar hemispheres. My results show that the shifts of weak-field field distributions in the two solar hemispheres have always the same sign as the new polarity of the polar field in the respective hemisphere and solar cycle. I also found that the hemispheric shifts change their sign in the late ascending to maximum phase of the solar cycle and attain their maximum in the early to mid-declining phase. This evolution of the hemispheric weak-field gives a new signal of the solar magnetic cycle. We also studied the long-term spatial-temporal evolution of the weak-field shift and skewness of the distribution of photospheric magnetic field values during solar cycles 21–24 in order to clarify the role and relation of the weak field values to the overall magnetic field evolution. Our results give evidence for the preference of even the weakest field elements toward the prevailing magnetic polarity since the emergence of an active region, and for a systematic coalescence of stronger magnetic fields of opposite to produce weak fields during the poleward drift of the surge
Original papers Original papers are not included in the electronic version of the dissertation. Getachew, T., Virtanen, I., & Mursula, K. (2017). Structure of the Photospheric Magnetic Field During Sector Crossings of the Heliospheric Magnetic Field. Solar Physics, 292(11). https://doi.org/10.1007/s11207-017-1198-9 http://jultika.oulu.fi/Record/nbnfi-fe201802083259 Getachew, T., Virtanen, I., & Mursula, K. (2019). Asymmetric Distribution of Weak Photospheric Magnetic Field Values. The Astrophysical Journal, 874(2), 116. https://doi.org/10.3847/1538-4357/ab0749 http://jultika.oulu.fi/Record/nbnfi-fe2019061320447 Getachew, T., Virtanen, I., & Mursula, K. (2019). A New Signal of the Solar Magnetic Cycle: Opposite Shifts of Weak Magnetic Field Distributions in the Two Hemispheres. Geophysical Research Letters, 46(16), 9327–9333. https://doi.org/10.1029/2019gl083339 Mursula, K., Getachew, T., & Virtanen, I. (2019). Spatial-temporal evolution of photospheric weak-field shifts in solar cycles 21-24. Astron. Astrophys., submitted
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Wood, Gillian Ann. "Field arrangements in the West Riding of Yorkshire in the High Middle Ages." Thesis, University of Leeds, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275806.

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Lavinsky, D. V. "Structural analysis of the technological systems under electromagnetic field action." Thesis, Center of educational literature, 2016. http://repository.kpi.kharkov.ua/handle/KhPI-Press/22372.

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Stewart, Kelley Christine. "Quantitative Hydrodynamics Analysis of Left Ventricular Diastolic Dysfunction using Color M-Mode Echocardiography." Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/35466.

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Numerous studies have shown that cardiac diastolic dysfunction and diastolic filling play a critical role in dictating overall cardiac health and demonstrated that the filling wave propagation speed is a significant index of the severity of diastolic dysfunction. However, the governing flow physics underlying the relationship between propagation speed and diastolic dysfunction are poorly understood. More importantly, currently there is no reliable metric to allow clinicians the ability to diagnose cardiac dysfunction. There is a greater need than ever for more accurate and robust diagnostic tools with the increasing number of deaths caused by this disease. Color M-mode (CMM) echocardiography is a technique that is commonly used in the diagnosis of Left Ventricular Diastolic Dysfunction (LVDD) and is used as the image modality in this work. The motivation for the current work is a hypothesized change in the mechanism driving early diastolic filling. The early filling wave of a healthy patient is driven by a rapid early diastolic relaxation creating a pressure difference within the left ventricle despite the fact the left ventricular volume is increasing. As diastolic dysfunction progresses, the left ventricular relaxation declines and it is hypothesized that the left atrial pressure rises to create the favorable pressure difference needed to drive early diastole. This changes the mechanism driving early diastolic filling from a pulling mechanism primary driven by left ventricular relaxation to a pushing mechanism primarily driven by high left atrial pressure. Within this study, CMM echocardiography images from 125 patients spanning healthy and the three stages of LVDD are analyzed using a newly developed automated algorithm. For the first time, a series of isovelocity contours is utilized to estimate the conventional propagation velocity. A critical point within the early filling wave is quantified as the point of early filling velocity deceleration. The clinically used propagation velocity is compared to a novel critical point propagation velocity calculated as a weighted average of the propagation velocities before and after the critical point showing an increase in the correlation between decreasing diastolic dysfunction stage and decreasing propagation velocity. For the first time the spatial pressure distributions calculated as the pressure relative to the mitral valve pressure at each location from the mitral valve to the ventricular apex, are quantified and analyzed at the instant of peak mitral to apical pressure difference for patients with varying stages of LVDD. The analysis of the spatial pressure distribution revealed three filling regions present in all patients. The pressure filling regions were used to calculate a useful filling efficiency with healthy patients having a useful filling efficiency of 64.8 ± 12.7% and severely diseased filling patients having an efficiency of 37.1 ± 12.1%. The newly introduced parameters and analysis of the CMM echocardiography data supports the hypothesis of a change in the mechanism driving early diastolic efficiency by displaying a decline in the early diastolic propagation velocity earlier into the left ventricle for severely diseased patients than for healthy filling patients and a premature breakup of the progressive pressure gradient fueling early diastolic filling in severely diseased patients.
Master of Science
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Fisher, Aaron Jay. "Predicting spatial distribution of critical pore types and their influence on reservoir quality, Canyon (Pennsylvanian) Reef reservoir, Diamond M field, Texas." Texas A&M University, 2005. http://hdl.handle.net/1969.1/4808.

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This study examined the stratigraphic architecture, depositional and diagenetic histories, and resulting reservoir characteristics that have influenced the occurrence, distribution, and quality of flow units in the Diamond M field, Scurry County, Texas. The study area is located in the Midland Basin. The field has production from the Canyon (Pennsylvanian) Horseshoe Atoll carbonate buildup. Recent drilling in the Diamond M field was done to evaluate ways to improve recovery by water flooding. Classification of depositional texture based on detailed petrologic and petrographic studies on three cores was done. Subsequent genetic classification of pore types by thin section petrography revealed three dominant pore types: intramatrix, moldic, and vuggy. The reservoir was zoned according to dominant pore type and log signatures to evaluate correlations at field scale by using neutron logs. Equations determined from core analyses provided equations used for estimating porosity and permeability, which were used to develop a ranking scheme for reservoir quality based on good, intermediate, and poor flow units at field scale. Ultimately slice maps of reservoir quality at a 10 ft interval for a 150 ft section of the Canyon Reef reservoir were developed. These reservoir quality maps will provide a useful tool for the design and implementation of accurate and profitable development programs.
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Shiran, M. B. "An investigation of the mode of action of dye/paper method of recording intensity distribution in an ultrasound field." Thesis, University of Aberdeen, 1993. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU059239.

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Ultrasound (the frequency range above 20 KHz) at intensities of 0-3.0 Wcm-2 is used in physical medicine to treat a variety of conditions (joint contractures, fibrosis and scarring and severe pain due to disorders such as frozen shoulder and capsulitis). It is believed to produce a reduction in pain and swelling and increase movement of joints affected by diseases such as arthritis. It is also used to generate hyperthermia for the treatment of neoplastic tumours. The technique involves irradiating tissues with either continuous or pulsed mode ultrasound, using either the field from a single or multielement transducer. Geometrically similar ultrasound transducers even from the same batch can have significantly different efficiencies and the resulting field distributions can also vary. There are several pieces of information required to characterize an ultrasound source. They are frequency, power output, spatial average and spatial peak intensity and details of ultrasonic field distribution. This application of ultrasound requires an experimental method to define the intensity distribution generated by a transducer or array of transducers. A number of different techniques have been used to record intensity distribution. These include sheets of liquid crystal on an absorbing surface, detection of signals using hydrophone probes, thermocouple probes, thermistor probes and the Schlieren technique. The dye/paper method and Starch iodine plate have been developed for the observation of the ultrasonic fields and evaluation of the source pattern.
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Hällstig, Emil. "Nematic Liquid Crystal Spatial Light Modulators for Laser Beam Steering." Doctoral thesis, Uppsala University, Quantum Chemistry, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4693.

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Laser beam control is important in many applications. Phase modulating spatial light modulators (SLMs) can be used to electronically alter the phase distribution of an optical wave-front and thus change the direction and shape of a laser beam. Physical constraints set limitations to the SLM and an ideal phase distribution can usually not be realised. In order to understand how such components can be used for non-mechanical beam control three nematic liquid crystal (NLC) SLMs have been thoroughly characterised and modelled.

The pixel structure and phase quantisation give a discrepancy between ideal and realised phase distributions. The impact on beam steering capability was examined by measurements and simulations of the intensity distribution in the far-field.

In two of the studied SLMs the pixel period was shorter than the thickness of the LC layer giving the optical phase shift. This results in a so-called “fringing field”, which was shown to degrade the phase modulation and couple light between polarisation modes. The deformation of the LC was simulated and a finite-difference time-domain (FDTD) algorithm was used to calculate how polarised light propagates through the optically anisotropic SLM.

Non-mechanical beam steering and tracking in an optical free-space communication link were demonstrated. Continual optimisation of the steering angle was achieved by feedback from a video camera.

The optical properties of the SLM in the time period right after a voltage update were studied. It was shown how light is redistributed between orders during the switching from one blazed grating to another. By appropriate choice of the blazed gratings the effects on the diffraction efficiency can be minimised.

The detailed knowledge of the SLM structure and its response to electronic control makes it possible to predict and optimise the device performance in future systems.

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Books on the topic "Mode field spatial distribution"

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Leighton, David A. Spatial distribution of selenium and other inorganic constituents in ground water underlying a drained agricultural field, western San Joaquin Valley, California. Sacramento, Calif: U.S. Geological Survey, 1992.

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Miller, Paul C. H. Automatic Recording by Application Machinery of Rates and Spatial Distribution of Field Inputs (Proceedings of the International Fertiliser Society S.). International Fertiliser Society, 1999.

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Veech, Joseph A. Habitat Ecology and Analysis. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198829287.001.0001.

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Habitat is crucial to the survival and reproduction of individual organisms as well as persistence of populations. As such, species-habitat relationships have long been studied, particularly in the field of wildlife ecology and to a lesser extent in the more encompassing discipline of ecology. The habitat requirements of a species largely determine its spatial distribution and abundance in nature. One way to recognize and appreciate the over-riding importance of habitat is to consider that a young organism must find and settle into the appropriate type of habitat as one of the first challenges of life. This process can be cast in a probabilistic framework and used to better understand the mechanisms behind habitat preferences and selection. There are at least six distinctly different statistical approaches to conducting a habitat analysis – that is, identifying and quantifying the environmental variables that a species most strongly associates with. These are (1) comparison among group means (e.g., ANOVA), (2) multiple linear regression, (3) multiple logistic regression, (4) classification and regression trees, (5) multivariate techniques (Principal Components Analysis and Discriminant Function Analysis), and (6) occupancy modelling. Each of these is lucidly explained and demonstrated by application to a hypothetical dataset. The strengths and weaknesses of each method are discussed. Given the ongoing biodiversity crisis largely caused by habitat destruction, there is a crucial and general need to better characterize and understand the habitat requirements of many different species, particularly those that are threatened and endangered.
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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.
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Certoma, Chiara, Susan Noori, and Martin Sondermann, eds. Urban gardening and the struggle for social and spatial justice. Manchester University Press, 2019. http://dx.doi.org/10.7228/manchester/9781526126092.001.0001.

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It is increasingly clear that, alongside the spectacular forms of justice activism, the actually existing just city outcomes from different everyday practices of performative politics that produce transformative trajectories and alternative realities in response to particular injustices in situated contexts. The massive diffusion of urban gardening practices (including allotments, community gardens, guerrilla gardening and the multiple, inventive forms of gardening the city) deserve a special attention as experiential learning and in-becoming responses to spatial politics, able to articulate different forms of power and resistance to current state of unequal distribution of benefits and burdens in the urban space. While advancing their socio-environmental claims, urban gardeners makes evident that the physical disposition of living beings and non-living things can both determine and perpetuate injustices or create justice spaces. In so doing, urban gardeners question the inequality-biased structuring and functioning of social formations (most notably urban deprivation, lack of public decision and engagement, and marginalization processes); and conversely create (or allow the creation of) spaces of justice in contemporary cities. This book presents a selection of contributions investigating the possibility and capability of urban gardeners to effectively tackling with spatial injustice; and it offers the readers a sound theoretically-grounded reflections on the topic. Building upon on-the-field experiences in European cities, it presents a wide range of engaged scholarly researches that investigate whether, how and to what extend urban gardening is able to contrast inequalities and disparities in living conditions.
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El uso de Sistemas de Información Geográfica (SIG) en la arqueología sudamericana. Oxford: BAR S2497 South American Archaeology Series 18, 2013.

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Schomer, Donald L., Charles M. Epstein, Susan T. Herman, Douglas Maus, and Bruce J. Fisch. Recording Principles. Edited by Donald L. Schomer and Fernando H. Lopes da Silva. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780190228484.003.0005.

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This chapter reviews the technical aspects of recording and reviewing clinical electroencephalograms (EEGs) and related biopotentials. While advances in engineering technology have revolutionized EEG machines, the basic principles underlying accurate representation of brain activity are largely unchanged. The first section reviews the analog EEG components, and the second section discusses analog-to-digital conversion, digital filters, and display and storage parameters. Digital EEG machines are now less expensive and their capabilities far surpass those of analog machines. The third section reviews how electrode positions and systems of signal display (montages) can be used to determine the polarity and field of EEG signals. The final section describes how other biopotentials are acquired and displayed. Polygraphy can provide crucial information on other physiological processes that can impact EEG activity and can help identify potential artifactual signals. We highlight recent advances that allow the recording of a broader range of EEG frequencies and spatial distribution.
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Book chapters on the topic "Mode field spatial distribution"

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Kaur, Gagandeep, and Harshawardhan Wanare. "Engineering Spatial Field Distribution of Modes in Photonic Crystal Cavities." In Springer Proceedings in Physics, 857–60. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-15-9259-1_197.

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Raghavan, Ram, and Roman Ganta. "Considerations for predicting climate change implications on future spatial distribution ranges of ticks." In Climate, ticks and disease, 38–43. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789249637.0006.

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Abstract This chapter focuses on spatial distribution models (SDMs) that are essential to producing reliable models of tick distributions, both in the present time and in the future, under climate change scenarios. It highlights the opinion that careful consideration of the methods is necessary in building SDMs, model assumptions, the limitations in predictions and making a careful interpretation of predictions, if possible, supported by field observations.
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Callejón-Leblic, M. A., and Pedro C. Miranda. "A Computational Parcellated Brain Model for Electric Field Analysis in Transcranial Direct Current Stimulation." In Brain and Human Body Modeling 2020, 81–99. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-45623-8_5.

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AbstractRecent years have seen the use of increasingly realistic electric field (EF) models to further our knowledge of the bioelectric basis of noninvasive brain techniques such as transcranial direct current stimulation (tDCS). Such models predict a poor spatial resolution of tDCS, showing a non-focal EF distribution with similar or even higher magnitude values far from the presumed targeted regions, thus bringing into doubt the classical criteria for electrode positioning. In addition to magnitude, the orientation of the EF over selected neural targets is thought to play a key role in the neuromodulation response. This chapter offers a summary of recent works which have studied the effect of simulated EF magnitude and orientation in tDCS, as well as providing new results derived from an anatomically representative parcellated brain model based on finite element method (FEM). The results include estimates of mean and peak tangential and normal EF values over different cortical regions and for various electrode montages typically used in clinical applications.
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Schmidt, K. H., and T. Boller. "Luminosity Function and Spatial Distribution of Nearby Galaxies." In Astronomy from Wide-Field Imaging, 577–81. Dordrecht: Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-011-1146-1_120.

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Riel, Stefanie, Mohammad Bashiri, Werner Hemmert, and Siwei Bai. "Computational Models of Brain Stimulation with Tractography Analysis." In Brain and Human Body Modeling 2020, 101–17. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-45623-8_6.

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AbstractComputational human head models have been used in studies of brain stimulation. These models have been able to provide useful information that can’t be acquired or difficult to acquire from experimental or imaging studies. However, most of these models are purely volume conductor models that overlooked the electric excitability of axons in the white matter of the brain. We hereby combined a finite element (FE) model of electroconvulsive therapy (ECT) with a whole-brain tractography analysis as well as the cable theory of neuronal excitation. We have reconstructed a whole-brain tractogram with 2000 neural fibres from diffusion-weighted magnetic resonance scans and extracted the information on electrical potential from the FE ECT model of the same head. Two different electrode placements and three different white matter conductivity settings were simulated and compared. We calculated the electric field and second spatial derivatives of the electrical potential along the fibre direction, which describes the activating function for homogenous axons, and investigated sensitive regions of white matter activation. Models with anisotropic white matter conductivity yielded the most distinctive electric field and activating function distribution. Activation was most likely to appear in regions between the electrodes where the electric potential gradient is most pronounced.
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Yau, Tai-Wei, Chau-Hwang Lee, and Jyhpyng Wang. "Spatial-temporal field distribution of self-focused femtosecond pulses." In Springer Series in Chemical Physics, 106–8. Berlin, Heidelberg: Springer Berlin Heidelberg, 1998. http://dx.doi.org/10.1007/978-3-642-72289-9_32.

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Al-Mamari, Mahmood M., Sameh A. Kantoush, and Tetsuya Sumi. "Innovative Monitoring Techniques for Wadi Flash Flood by Using Image-Based Analysis." In Natural Disaster Science and Mitigation Engineering: DPRI reports, 251–66. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-2904-4_9.

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AbstractFlash floods in wadi systems are a very important environmental issue, and their monitoring is necessary for many applications, including water resource management, irrigation and flood control. However, monitoring networks are very rare and lack spatial distribution features. In this study, image-based techniques were used to quantify and monitor flash floods in wadi channels by using two different methods. In the first section, we employed photogrammetry processing technique to quantify post-peak flood discharges by using a drone survey to build a digital elevation model (DEM) with a high resolution and calibrated and validated the model with a field survey (levelling measurements). This technique used drone-collected images to construct a DEM for extracting a cross-sectional profile and elevation points to calculate the peak discharge using the slope-area method with the Manning equation. In the second section, we combined the previous technique with the large-scale particle image velocimetry (LSPIV) technique to measure flash flood discharge by installing a fixed camera on a road bridge crossing a wadi channel and using a digitally extracted cross section from the DEM in the analysis. The results of those techniques show a high efficiency that is equivalent to that of conventional methods.
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Sperl, C., H. Stanjek, and A. Berktold. "On-Site Measurements of the Spatial Distribution of Soil Water Content with Ground-Penetrating Radar." In Field Screening Europe, 157–60. Dordrecht: Springer Netherlands, 1997. http://dx.doi.org/10.1007/978-94-009-1473-5_36.

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Gamon, John A., Ran Wang, Hamed Gholizadeh, Brian Zutta, Phil A. Townsend, and Jeannine Cavender-Bares. "Consideration of Scale in Remote Sensing of Biodiversity." In Remote Sensing of Plant Biodiversity, 425–47. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-33157-3_16.

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AbstractA coherent and effective remote sensing (RS) contribution to biodiversity monitoring requires careful consideration of scale in all its dimensions, including spatial, temporal, spectral, and angular, along with biodiversity at different levels of biological organization. Recent studies of the relationship between optical diversity (spectral diversity) and biodiversity reveal a scale dependence that can be influenced by the RS methods used, vegetation type, and degree and nature of disturbance. To better understand these issues, we call for multi-scale field campaigns that test the effect of sampling scale, vegetation type, and degree of disturbance on the ability to detect different kinds of biodiversity, along with the development of improved models that incorporate both physical and biological principles as well as ecological and evolutionary theory. One goal of these studies would be to more closely match instrumentation and sampling scales to biological definitions of biodiversity and so improve optical diversity (spectral diversity) as a proxy for biodiversity. The ultimate goal would be to design and implement a truly effective, “scale-aware” global biodiversity monitoring system employing RS methods. Such a system could improve our understanding of the distribution and functional importance of biodiversity and enhance our ability to manage ecosystems for resilience and sustainability in a changing world.
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Berlucchi, G., S. Aglioti, M. Biscaldi, L. Chelazzi, M. Corbetta, and G. Tassinari. "Spatial Constraints on the Distribution of Selective Attention in the Visual Field." In Brain and Reading, 115–28. London: Macmillan Education UK, 1989. http://dx.doi.org/10.1007/978-1-349-10732-2_8.

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Conference papers on the topic "Mode field spatial distribution"

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Gruneisen, Mark T., Raymond C. Dymale, and Kurt E. Stoltenberg. "Free-space quantum key distribution with spatial modes of the optical field." In SPIE Security + Defence, edited by Roberto Zamboni, François Kajzar, Attila A. Szep, Colin Lewis, Douglas Burgess, Mark T. Gruneisen, Miloslav Dusek, and John G. Rarity. SPIE, 2011. http://dx.doi.org/10.1117/12.898926.

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Chen, Zhicheng, Yuequan Bao, and Hui Li. "The random field model of the spatial distribution of heavy vehicle loads on long-span bridges." In SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring, edited by Tribikram Kundu. SPIE, 2016. http://dx.doi.org/10.1117/12.2218968.

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Guell, F., A. R. Goni, J. O. Osso, L. A. Perez, E. A. Coronado, and J. R. Morante. "Retrieving the spatial distribution of cavity modes in ZnO nanowires by near-field imaging and electrodynamics simulations." In 2013 Conference on Lasers & Electro-Optics Europe & International Quantum Electronics Conference CLEO EUROPE/IQEC. IEEE, 2013. http://dx.doi.org/10.1109/cleoe-iqec.2013.6800946.

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Pougatch, Konstantin, Martha Salcudean, and Jennifer McMillan. "Average Droplet Diameter Spatial Distribution in a Spray After Gas-Assisted Atomization." In ASME 2010 International Mechanical Engineering Congress and Exposition. ASMEDC, 2010. http://dx.doi.org/10.1115/imece2010-39737.

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Gas-assisted atomization is used in many industries to produce finely dispersed droplets. Knowledge about the droplet size distribution guides the design and development of the nozzle as well as of the whole processes. This knowledge can be obtained through experimental and modeling works that usually complement each another. In this paper we present an application of the mathematical model previously developed for gas-assisted atomization to the prediction of the average droplet diameter distribution in a spray and compare the results with experimental findings. The model is based on a two-fluid Eulerian-Eulerian treatment of the motion of the phases with a catastrophic phase inversion (atomization). It also includes the compressibility effects for the gaseous phase and can be applied to both the flow through the nozzle-atomizer and to the dispersion of the spray. The model accounts for the break-up and coalescence of bubbles and droplets due to interfacial shear and collisions. The diameter of the particle (bubble or droplet) is represented by its local mean average value that varies throughout the flow field. Simulations are conducted for the flow of air and water through the convergent-divergent nozzle, which is similar to the one used in commercial fluid cokers, a bitumen upgrading apparatus, for steam-assisted atomization of bitumen. It is found that while there are wide experimentally observed local distributions of the particle diameter, the concept of the average diameter still allows for satisfactory predictions of its average values and spatial variations. In agreement with the experiments, the numerical model demonstrated that the largest droplet diameter is located in the axial area, and the diameter values reduce towards the periphery of the jet. In addition, the average diameter increases slightly and its radial variation becomes more uniform as the distance from the nozzle orifice increases.
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Zhang, Zhenyang, Hongwei Ma, Chao Jin, Cheng Xue, and Yunlong Huang. "Application of PIV Measurements and Snapshot POD Analysis in a Cylinder Head of Diesel Engine." In ASME 2017 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/icef2017-3511.

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The characteristic of coolant flow field in the water jacket of a cylinder head plays an important role in heat exchange, which could even influence the diesel engine’s performance and service life. Measurements and analysis methods to coolant flow field are limited by the complex internal geometrical structure of the cylinder head. In this paper, flow fields in a small and complicated spatial structure are measured by particle image velocimetry (PIV) system and the data are analyzed using proper orthogonal decomposition (POD) method. Time varying coolant flow structures located among two valve seats, a fuel injector seat and a side wall in a real cylinder head are measured by a two dimensional PIV system. PIV results of three measuring planes are displayed in different ways to show flow structures in the water jacket. Distinctive areas can be recognized easily in distributions of different flow parameters. A snapshot POD method is employed to analyze PIV data. Flow structures, which contain different amount of energy, are decomposed into different modes by POD method. POD Mode 1 and ensemble mean flow field are compared together and the relevance index shows a relatively high similarity between these two flow fields. The results also indicate a significant convergence of energy distribution. Energy contained in Mode 1 varies from 22% to 61% of the total energy in different measuring planes. 90% of the total energy is captured in top 10% of the total modes which belong to low-order modes. Energy in high-order modes, which occupy more than 60% of the total modes, contains less than 1% of the total energy. In summary, this paper presents the application of PIV measurements to coolant flow field in a real cylinder head and data processing using a snapshot POD method to analyze PIV results. A set of comprehensive properties showing the spatial and temporal characteristics of coolant flow structure is discussed and concluded detailedly. The data obtained can be used to build an experimental database to optimize coolant flow field structures and verify CFD numerical simulations in order to promote coolant flow passage design and simulation credibility of the diesel engine cooling system.
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Zhang, Y., X. S. Mei, D. L. Zou, N. G. Sun, and J. J. Zhang. "A New Field Unbalance Estimation Method for Flexible Rotors." In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-65867.

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Current field unbalance estimation methods regards “flexible rotors with lumped mass” as the main research object, and most of them need a stop running to take trial weights. Due to its test speed closing to the critical speed, the process of balance is really complicated and dangerous. This paper concerns rotors which unbalance state shows a continuous spatial distribution. Firstly, a dynamic finite element (FE) model of the rotor system is built, the inherent relations and differences between the dynamics transfer matrix and influence coefficient (IC) matrix are analyzed, and then, an extended dynamics matrix with arbitrary dimension is obtained based on the principle of IC balancing method. Secondly, the continuous distribution mass eccentricity curve is represented as mass eccentricity point on each FE model node, and the unbalance forces imposing on each FE model node are identified by the extended dynamics matrix. Finally, the theoretic analysis and experiment is presented to verify this method, and the result shows that unbalance forces on all FE model nodes can be identified accurately with less measuring points, and higher order modal components of the distributed unbalance are balanced effectively.
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Sui, Xin, Yifan Yu, and Liu Huhui. "Measurement of spatial equity : a case study of nursing institution." In 55th ISOCARP World Planning Congress, Beyond Metropolis, Jakarta-Bogor, Indonesia. ISOCARP, 2019. http://dx.doi.org/10.47472/bgdi1793.

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Equity and justice have always been important norms in the field of urban planning. With the gradual deepening of understanding of residential environment, the research context of equity and justice related to location is becoming more and more sophisticated. Recently, varieties of subjects Including Public Health and Geography focus on the inequity of public resources in spatial distribution and how to measure the degree of this gap. In general, the mainstream measurement methods can be summarized into two categories: (1) The description of phenomenon caused by the spatial inequities, and accessibility is a typical method of this type. (2) the direct quantification of inequity, such as Gink Coefficient which is originated from the economics field and introduced into the measurement of health equity, and Getis-Ord General G, together with Moran’ index is the most commonly method used into the general spatial autocorrelation. In this paper, based on the overall literature review of the concept of equity in the study using these methods and a summary of their specific context of the measurement using, nursing institution in Shanghai, China are regarded as a typical case to practice these methods and compare the differences in using. Meantime, the impact of the politics and planning related to this special facility is also been considered. Results show that, accessibility of nursing institution among elderly groups is much different under different research distance, and the overall trend seems like the research units in suburb appears higher accessibility than those in highly urbanized area. And Gink Coefficient helps us determine the proportion of the elderly population in different reachable areas in Shanghai is within a reasonable range. However, Global Moran’ index provide reliable evidence that the existence of the aggregation combined by the high-value units. It indicates that there are inequities among the distribution of aged-nursing resources, and Local Moran I （LISA）help us to find the specific boundaries of these areas. In general, in the study of the equity related to location, accessibility can only reflect the differences phenomenon in distribution, but it is not clear to describe this gap to what extent, and it’s difficult to achieve the possibility of comparison among different periods and different subjects. The Gini coefficient often focuses on the unfairness of the distribution of people, but ignored the aggregation characteristics of the spatial dimension, which the analysis of spatial autocorrelation can make up. All these methods proved that it’s necessary to consider both the spatial distribution of supply and demand. And the discussion about equity related to location should be strictly qualified in study.
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Garbatov, Yordan, and C. Guedes Soares. "Spatial Corrosion Wastage Modelling of Steel Plates Subjected to Marine Environments." In ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/omae2017-61751.

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The objective of the present study is to analyse and identify the most suitable corrosion degradation model, fitted with real corrosion depth measurement data sets and to reproduce the corroded steel plate surface as a function of time and spatial distribution using advanced statistical methods. An approach for properly identifying the best fitted model to real corrosion depth measurement data sets is employed. A sequence dependent data analysis is performed based on the fast Fourier transform, which is used as an input for a random field modelling of the corroded steel plate surfaces.
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Cordera Piñera, Rubén, Roberto Sañudo, Luigi Dell'Olio, and Ángel Ibeas. "Demand prediction model for regional railway services considering spatial effects between stations." In CIT2016. Congreso de Ingeniería del Transporte. Valencia: Universitat Politècnica València, 2016. http://dx.doi.org/10.4995/cit2016.2016.4053.

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The railways are a priority transport mode for the European Union given their safety record and environmental sustainability. Therefore it is important to have quantitative models available which allow passenger demand for rail travel to be simulated for planning purposes and to evaluate different policies. The aim of this article is to specify and estimate trip distribution models between railway stations by considering the most influential demand variables. Two types of models were estimated: Poisson regression and gravity. The input data were the ticket sales on a regional line in Cantabria (Spain) which were provided by the Spanish railway infrastructure administrator (ADIF – RAM). The models have also considered the possible existence of spatial effects between train stations. The results show that the models have a good fit to the available data, especial the gravity models constrained by origins and destinations. Furthermore, the gravity models which considered the existence of spatial effects between stations had a significantly better fit than the Poisson models and the gravity models that did not consider this phenomenon. The proposed models have therefore been shown to be good support tools for decision making in the field of railway planning.DOI: http://dx.doi.org/10.4995/CIT2016.2016.4053
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Owejan, J. P., T. A. Trabold, D. L. Jacobson, M. Arif, and S. G. Kandlikar. "Effects of Flow Field and Diffusion Layer Properties on Water Accumulation in a PEM Fuel Cell." In ASME 2007 5th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2007. http://dx.doi.org/10.1115/icnmm2007-30142.

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Water is the main product of the electrochemical reaction in a proton exchange membrane (PEM) fuel cell. Where the water is produced over the active area of the cell, and how it accumulates within the flow fields and gas diffusion layers, strongly affects the performance of the device and influences operational considerations such as freeze and durability. In this work, the neutron radiography method was used to obtain two-dimensional distributions of liquid water in operating 50 cm2 fuel cells. Variations were made of flow field channel and diffusion media properties, to assess the effects on the overall volume and spatial distribution of accumulated water. Flow field channels with hydrophobic coating retain more water, but the distribution of a greater number of smaller slugs in the channel area improves fuel cell performance at high current density. Channels with triangular geometry retain less water than rectangular channels of the same cross-sectional area, and the water is mostly trapped in the two corners adjacent to the diffusion media. Also, it was found that cells constructed using diffusion media with lower in-plane gas permeability tended to retain less water. In some cases, large differences in fuel cell performance were observed with very small changes in accumulated water volume, suggesting that flooding within the electrode layer or at the electrode-diffusion media interface is the primary cause of the significant mass transport voltage loss.
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Reports on the topic "Mode field spatial distribution"

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Russo, David, and William A. Jury. Characterization of Preferential Flow in Spatially Variable Unsaturated Field Soils. United States Department of Agriculture, October 2001. http://dx.doi.org/10.32747/2001.7580681.bard.

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Preferential flow appears to be the rule rather than the exception in field soils and should be considered in the quantitative description of solute transport in the unsaturated zone of heterogeneous formations on the field scale. This study focused on both experimental monitoring and computer simulations to identify important features of preferential flow in the natural environment. The specific objectives of this research were: (1) To conduct dye tracing and multiple tracer experiments on undisturbed field plots to reveal information about the flow velocity, spatial prevalence, and time evolution of a preferential flow event; (2) To conduct numerical experiments to determine (i) whether preferential flow observations are consistent with the Richards flow equation; and (ii) whether volume averaging over a domain experiencing preferential flow is possible; (3) To develop a stochastic or a transfer function model that incorporates preferential flow. Regarding our field work, we succeeded to develop a new method for detecting flow patterns faithfully representing the movement of water flow paths in structured and non-structured soils. The method which is based on application of ammonium carbonate was tested in a laboratory study. Its use to detect preferential flow was also illustrated in a field experiment. It was shown that ammonium carbonate is a more conservative tracer of the water front than the popular Brilliant Blue. In our detailed field experiments we also succeeded to document the occurrence of preferential flow during soil water redistribution following the cessation of precipitation in several structureless field soils. Symptoms of the unstable flow observed included vertical fingers 20 - 60 cm wide, isolated patches, and highly concentrated areas of the tracers in the transmission zone. Soil moisture and tracer measurements revealed that the redistribution flow became fingered following a reversal of matric potential gradient within the wetted area. Regarding our simulation work, we succeeded to develop, implement and test a finite- difference, numerical scheme for solving the equations governing flow and transport in three-dimensional, heterogeneous, bimodal, flow domains with highly contrasting soil materials. Results of our simulations demonstrated that under steady-state flow conditions, the embedded clay lenses (with very low conductivity) in bimodal formations may induce preferential flow, and, consequently, may enhance considerably both the solute spreading and the skewing of the solute breakthrough curves. On the other hand, under transient flow conditions associated with substantial redistribution periods with diminishing water saturation, the effect of the embedded clay lenses on the flow and the transport might diminish substantially. Regarding our stochastic modeling effort, we succeeded to develop a theoretical framework for flow and transport in bimodal, heterogeneous, unsaturated formations, based on a stochastic continuum presentation of the flow and a general Lagrangian description of the transport. Results of our analysis show that, generally, a bimodal distribution of the formation properties, characterized by a relatively complex spatial correlation structure, contributes to the variability in water velocity and, consequently, may considerably enhance solute spreading. This applies especially in formations in which: (i) the correlation length scales and the variances of the soil properties associated with the embedded soil are much larger than those of the background soil; (ii) the contrast between mean properties of the two subdomains is large; (iii) mean water saturation is relatively small; and (iv) the volume fraction of the flow domain occupied by the embedded soil is relatively large.
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Ansari, S. M., E. M. Schetselaar, and J. A. Craven. Three-dimensional magnetotelluric modelling of the Lalor volcanogenic massive-sulfide deposit, Manitoba. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/328003.

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Unconstrained magnetotelluric inversion commonly produces insufficient inherent resolution to image ore-system fluid pathways that were structurally thinned during post-emplacement tectonic activity. To improve the resolution in these complex environments, we synthesized the 3-D magnetotelluric (MT) response for geologically realistic models using a finite-element-based forward-modelling tool with unstructured meshes and applied it to the Lalor volcanogenic massive-sulfide deposit in the Snow Lake mining camp, Manitoba. This new tool is based on mapping interpolated or simulated resistivity values from wireline logs onto unstructured tetrahedral meshes to reflect, with the help of 3-D models obtained from lithostratigraphic and lithofacies drillhole logs, the complexity of the host-rock geological structure. The resulting stochastic model provides a more realistic representation of the heterogeneous spatial distribution of the electric resistivity values around the massive, stringer, and disseminated sulfide ore zones. Both models were combined into one seamless tetrahedral mesh of the resistivity field. To capture the complex resistivity distribution in the geophysical forward model, a finite-element code was developed. Comparative analyses of the forward models with MT data acquired at the Earth's surface show a reasonable agreement that explains the regional variations associated with the host rock geological structure and detects the local anomalies associated with the MT response of the ore zones.
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Libelo, Louis F., and Guy E. Pisane. The Normal Mode E- and H-Field Distribution in the Concentric Spherical Cavity. Fort Belvoir, VA: Defense Technical Information Center, April 1990. http://dx.doi.org/10.21236/ada225388.

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Jurkevitch, Edouard, Carol R. Lauzon, Boaz Yuval, and Sue D. McCombs. Bacteria - Medfly Interactions: a Spatial, Temporal and Functional Study. United States Department of Agriculture, July 2010. http://dx.doi.org/10.32747/2010.7697102.bard.

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Our progress overallhas been gratifying. We have been able to characterize the microflora of wild and mass reared flies, determine their mode of transmission, their spatial distribution, and their contribution to the fitness of the fly. In addition we have been able to demonstrate that manipulation of the bacteria residing in the gut of sterile males, significantly improves their reproductive success. These points are expanded below.
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Heinz, Kevin, Itamar Glazer, Moshe Coll, Amanda Chau, and Andrew Chow. Use of multiple biological control agents for control of western flower thrips. United States Department of Agriculture, 2004. http://dx.doi.org/10.32747/2004.7613875.bard.

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The western flower thrips (WFT), Frankliniella occidentalis (Pergande), is a serious widespread pest of vegetable and ornamental crops worldwide. Chemical control for Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) on floriculture or vegetable crops can be difficult because this pest has developed resistance to many insecticides and also tends to hide within flowers, buds, and apical meristems. Predatory bugs, predatory mites, and entomopathogenic nematodes are commercially available in both the US and Israel for control of WFT. Predatory bugs, such as Orius species, can suppress high WFT densities but have limited ability to attack thrips within confined plant parts. Predatory mites can reach more confined habitats than predatory bugs, but kill primarily first-instar larvae of thrips. Entomopathogenic nematodes can directly kill or sterilize most thrips stages, but have limited mobility and are vulnerable to desiccation in certain parts of the crop canopy. However, simultaneous use of two or more agents may provide both effective and cost efficient control of WFT through complimentary predation and/or parasitism. The general goal of our project was to evaluate whether suppression of WFT could be enhanced by inundative or inoculative releases of Orius predators with either predatory mites or entomopathogenic nematodes. Whether pest suppression is best when single or multiple biological control agents are used, is an issue of importance to the practice of biological control. For our investigations in Texas, we used Orius insidiosus(Say), the predatory mite, Amblyseius degeneransBerlese, and the predatory mite, Amblyseius swirskii(Athias-Henriot). In Israel, the research focused on Orius laevigatus (Fieber) and the entomopathogenic nematode, Steinernema felpiae. Our specific objectives were to: (1) quantify the spatial distribution and population growth of WFT and WFT natural enemies on greenhouse roses (Texas) and peppers (Israel), (2) assess interspecific interactions among WFT natural enemies, (3) measure WFT population suppression resulting from single or multiple species releases. Revisions to our project after the first year were: (1) use of A. swirskiiin place of A. degeneransfor the majority of our predatory mite and Orius studies, (2) use of S. felpiaein place of Thripinema nicklewoodi for all of the nematode and Orius studies. We utilized laboratory experiments, greenhouse studies, field trials and mathematical modeling to achieve our objectives. In greenhouse trials, we found that concurrent releases of A.degeneranswith O. insidiosusdid not improve control of F. occidentalis on cut roses over releases of only O. insidiosus. Suppression of WFT by augmentative releases A. swirskiialone was superior to augmentative releases of O. insidiosusalone and similar to concurrent releases of both predator species on cut roses. In laboratory studies, we discovered that O. insidiosusis a generalist predator that ‘switches’ to the most abundant prey and will kill significant numbers of A. swirskiior A. degeneransif WFTbecome relatively less abundant. Our findings indicate that intraguild interactions between Orius and Amblyseius species could hinder suppression of thrips populations and combinations of these natural enemies may not enhance biological control on certain crops. Intraguild interactions between S. felpiaeand O. laevigatus were found to be more complex than those between O. insidiosusand predatory mites. In laboratory studies, we found that S. felpiaecould infect and kill either adult or immature O. laevigatus. Although adult O. laevigatus tended to avoid areas infested by S. felpiaein Petri dish arenas, they did not show preference between healthy WFT and WFT infected with S. felpiaein choice tests. In field cage trials, suppression of WFT on sweet-pepper was similar in treatments with only O. laevigatus or both O. laevigatus and S. felpiae. Distribution and numbers of O. laevigatus on pepper plants also did not differ between cages with or without S. felpiae. Low survivorship of S. felpiaeafter foliar applications to sweet-pepper may explain, in part, the absence of effects in the field trials. Finally, we were interested in how differential predation on different developmental stages of WFT (Orius feeding on WFT nymphs inhabiting foliage and flowers, nematodes that attack prepupae and pupae in the soil) affects community dynamics. To better understand these interactions, we constructed a model based on Lotka-Volterra predator-prey theory and our simulations showed that differential predation, where predators tend to concentrate on one WFT stage contribute to system stability and permanence while predators that tend to mix different WFT stages reduce system stability and permanence.
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Dasberg, Shmuel, Jan W. Hopmans, Larry J. Schwankl, and Dani Or. Drip Irrigation Management by TDR Monitoring of Soil Water and Solute Distribution. United States Department of Agriculture, August 1993. http://dx.doi.org/10.32747/1993.7568095.bard.

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Drip irrigation has the potential of high water use efficiency, but actual water measurement is difficult because of the limited wetted volume. Two long-term experiments in orchards in Israel and in California and several field crop studies supported by this project have demonstrated the feasibility of precise monitoring of soil water distribution for drip irrigation in spite of the limited soil wetting. Time Domain Reflectometry (TDR) enables in situ measurement of soil water content of well defined small volumes. Several approaches were tried in monitoring the soil water balance in the field during drip irrigation. These also facilitated the estimation of water uptake: 1. The use of multilevel moisture probe TDR system. This approach proved to be of limited value because of the extremely small diameter of measurement. 2. The placement of 20 cm long TDR probes at predetermined distances from the drippers in citrus orchards. 3. Heavy instrumentation with neutron scattering access tubes and tensiometers of a single drip irrigated almond tree. 4. High resolution spatial and temporal measurements (0.1m x 0.1m grid) of water content by TDR in corn irrigated by surface and subsurface drip. The latter approach was accompanied by parametric modelling of water uptake intensity patterns by corn roots and superimposed with analytical solutions for water flow from point and line sources. All this lead to general and physically based suggestions for the placement of soil water sensors for scheduling drip irrigation.
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Lundgren, Jonathan, Moshe Coll, and James Harwood. Biological control of cereal aphids in wheat: Implications of alternative foods and intraguild predation. United States Department of Agriculture, October 2014. http://dx.doi.org/10.32747/2014.7699858.bard.

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The overall objective of this proposal is to understand how realistic strategies for incorporating alternative foods into wheat fields affect the intraguild (IG) interactions of omnivorous and carnivorous predators and their efficacy as biological control agents. Cereal aphids are a primary pest of wheat throughout much of the world. Naturally occurring predator communities consume large quantities of cereal aphids in wheat, and are partitioned into aphid specialists and omnivores. Within wheat fields, the relative abilities of omnivorous and carnivorous predators to reduce cereal aphids depend heavily on the availability, distribution and type of alternative foods (alternative prey, sugar, and pollen), and on the intensity and direction of IG predation events within this community. A series of eight synergistic experiments, carefully crafted to accomplish objectives while accounting for regional production practices, will be conducted to explore how cover crops (US, where large fields preclude effective use of field margins) and field margins (IS, where cover crops are not feasible) as sources of alternative foods affect the IG interactions of predators and their efficacy as biological control agents. These objectives are: 1. Determine the mechanisms whereby the availability of alternative prey and plant-provided resources affect pest suppression by omnivorous and carnivorous generalist predators; 2. Characterize the intensity of IGP within generalist predator communities of wheat systems and assess the impact of these interactions on cereal aphid predation; and 3. Evaluate how spatial patterns in the availability of non-prey resources and IGP affect predation on cereal aphids by generalist predator communities. To accomplish these goals, novel tools, including molecular and biochemical gut content analysis and geospatial analysis, will be coupled with traditional techniques used to monitor and manipulate insect populations and predator efficacy. Our approach will manipulate key alternative foods and IG prey to determine how these individual interactions contribute to the ability of predators to suppress cereal aphids within systems where cover crop and field margin management strategies are evaluated in production scale plots. Using these strategies, the proposed project will not only provide cost-effective and realistic solutions for pest management issues faced by IS and US producers, but also will provide a better understanding of how spatial dispersion, IG predation, and the availability of alternative foods contribute to biological control by omnivores and carnivores within agroecosystems. By reducing the reliance of wheat producers on insecticides, this proposal will address the BARD priorities of increasing the efficiency of agricultural production and protecting plants against biotic sources of stress in an environmentally friendly and sustainable manner.
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Spatial distribution of selenium and other inorganic constituents in ground water underlying a drained agricultural field, western San Joaquin Valley, California. US Geological Survey, 1992. http://dx.doi.org/10.3133/wri914119.

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9

Coastal Lidar And Radar Imaging System (CLARIS) mobile terrestrial lidar survey along the Outer Banks, North Carolina in Currituck and Dare counties. Coastal and Hydraulics Laboratory (U.S.), January 2020. http://dx.doi.org/10.21079/11681/39419.

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The Coastal Observation and Analysis Branch (COAB) located at the Field Research Facility (FRF) conducts quarterly surveys and post-storm surveys along up to 60 kilometers of coastline within the vicinity of the FRF to assess, evaluate, and provide updated observations of the morphology of the foreshore and dune system. The surveys are conducted using a mobile terrestrial LiDAR scanner coupled with an Inertial Navigation System (INS). Traditionally the surveys coincide with a low tide, exposing the widest swath of visible sediment to the scanner as well as enough wind-sea swell or texture to induce wave breaking upon the interior sandbars. The wave field is measured with X-Band radar which records a spatial time series of wave direction and speed. Data for the survey region was collected using the VZ-2000's mobile, 3D scanning mode where the scanner continuously rotates the line scan 360 degrees as the vehicle progresses forward. Elevation measurements are acquired on all sides of the vehicle except for the topography directly underneath the vehicle. As the vehicle moves forward, the next rotation will capture the previous position's occluded data area. Laser data is acquired in mobile 3D radar mode with a pulse repetition rate of 300kHz, theta resolution of 0.19 degrees and phi resolution of 0.625 degrees. Horizontal Datum NAD83(2011), Projection North Carolina State Plane (3200) meters; Vertical Datum NAVD88, meters with geoid09 applied.
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10

Coastal Lidar And Radar Imaging System (CLARIS) mobile terrestrial lidar survey along the Outer Banks, North Carolina in Currituck and Dare counties. Coastal and Hydraulics Laboratory (U.S.), January 2020. http://dx.doi.org/10.21079/11681/39419.

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Abstract:
The Coastal Observation and Analysis Branch (COAB) located at the Field Research Facility (FRF) conducts quarterly surveys and post-storm surveys along up to 60 kilometers of coastline within the vicinity of the FRF to assess, evaluate, and provide updated observations of the morphology of the foreshore and dune system. The surveys are conducted using a mobile terrestrial LiDAR scanner coupled with an Inertial Navigation System (INS). Traditionally the surveys coincide with a low tide, exposing the widest swath of visible sediment to the scanner as well as enough wind-sea swell or texture to induce wave breaking upon the interior sandbars. The wave field is measured with X-Band radar which records a spatial time series of wave direction and speed. Data for the survey region was collected using the VZ-2000's mobile, 3D scanning mode where the scanner continuously rotates the line scan 360 degrees as the vehicle progresses forward. Elevation measurements are acquired on all sides of the vehicle except for the topography directly underneath the vehicle. As the vehicle moves forward, the next rotation will capture the previous position's occluded data area. Laser data is acquired in mobile 3D radar mode with a pulse repetition rate of 300kHz, theta resolution of 0.19 degrees and phi resolution of 0.625 degrees. Horizontal Datum NAD83(2011), Projection North Carolina State Plane (3200) meters; Vertical Datum NAVD88, meters with geoid09 applied.
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