Academic literature on the topic 'Periodic patches'
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Journal articles on the topic "Periodic patches"
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GEORGESCU, PAUL, GABRIEL DIMITRIU, and ROBERT SINCLAIR. "IMPULSIVE CONTROL OF AN INTEGRATED PEST MANAGEMENT MODEL WITH DISPERSAL BETWEEN PATCHES." Journal of Biological Systems 18, no. 03 (September 2010): 535–69. http://dx.doi.org/10.1142/s0218339010003561.
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We consider a two-patch SI model of integrated pest management with dispersal of both susceptible and infective pests between patches. A biological control, consisting of the periodic release of infective pests and a chemical control, consisting of periodic and impulsive pesticide spraying, are employed in order to maintain the size of the pest population below an economically acceptable level. It is assumed that the spread of the disease which is inflicted on the pest population through the use of the biological control is characterized by a nonlinear force of infection expressed in an abstract form. A sufficient condition for the local stability of the susceptible pest-eradication periodic solution is found using Floquet theory for periodic systems of ordinary differential equations, an analysis of the influence of dispersal between patches being performed for several particular cases. Our numerical simulations indicate that an increase in the amount but not in the frequency of pesticide use may not result in control. We also show that patches which are stable in isolation can be destabilized by dispersal between patches.
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Franović, Igor, and Sebastian Eydam. "Patched patterns and emergence of chaotic interfaces in arrays of nonlocally coupled excitable systems." Chaos: An Interdisciplinary Journal of Nonlinear Science 32, no. 9 (September 2022): 091102. http://dx.doi.org/10.1063/5.0111507.
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We disclose a new class of patterns, called patched patterns, in arrays of non-locally coupled excitable units with attractive and repulsive interactions. The self-organization process involves the formation of two types of patches, majority and minority ones, characterized by uniform average spiking frequencies. Patched patterns may be temporally periodic, quasiperiodic, or chaotic, whereby chaotic patterns may further develop interfaces comprised of units with average frequencies in between those of majority and minority patches. Using chaos and bifurcation theory, we demonstrate that chaos typically emerges via a torus breakup and identify the secondary bifurcation that gives rise to chaotic interfaces. It is shown that the maximal Lyapunov exponent of chaotic patched patterns does not decay, but rather converges to a finite value with system size. Patched patterns with a smaller wavenumber may exhibit diffusive motion of chaotic interfaces, similar to that of the incoherent part of chimeras.
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JANG, HONG-KYU, YEON-GWAN LEE, JAE-HWAN SHIN, and CHUN-GON KIM. "ELECTROMAGNETIC WAVE ABSORBING TECHNIQUE USING PERIODIC PATTERNS FOR LOW RCS PATCH ARRAY ANTENNA." International Journal of Modern Physics B 27, no. 17 (July 3, 2013): 1350094. http://dx.doi.org/10.1142/s021797921350094x.
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This paper presents an electromagnetic wave absorbing technique to reduce a radar cross-section (RCS) of a patch array antenna without compromising their antenna performance. The technique is based on periodic patterns, which is made of resistive materials. The 2×2 patch array antenna with a resonance frequency of 3.0 GHz was designed and fabricated. To reduce the RCS of the patch array antenna, the periodic patterns using a square patch element were proposed and applied to the surface between the four antenna patches. The printed lossy periodic patterns have radar absorbing performance at 12.0 GHz frequency. The measured results show that the lossy periodic patterns have no significant effect on the antenna radiation performance. On the other hand, the RCS is reduced by more than 98% compared to the conventional antenna at the target frequency.
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Mokrani, Bilal, Renaud Bastaits, Mihaita Horodinca, Iulian Romanescu, Ioanica Burda, Régis Viguié, and André Preumont. "Parallel Piezoelectric Shunt Damping of Rotationally Periodic Structures." Advances in Materials Science and Engineering 2015 (2015): 1–12. http://dx.doi.org/10.1155/2015/162782.
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This paper considers the RL shunt damping of rotationally periodic structures with an array of regularly spaced piezoelectric patches. The technique is targeted to the damping of a specific mode withnnodal diameters. For this particular case, one can take advantage of the shape of the targeted mode to organize the piezoelectric patches as a modal filter (in parallel loops) which reduces the demand on the inductors of the tuned inductive shunt. In the case of a perfectly rotationally periodic structure, it is possible to organize 4npiezoelectric transducers (PZT patches) in two parallel loops of 2npatches each. In this way, the demand on the inductors is reduced by4n2as compared to independent loops, which may allow a fully passive integration of the RL shunt in a turbomachinery application. The method is first illustrated experimentally on a circular plate; it is then applied to a prototype of an industrial bladed drum. The influence of blade mistuning is investigated.
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ZHANG, LONG, and ZHIDONG TENG. "PERMANENCE IN A PERIODIC PREDATOR–PREY SYSTEM WITH PREY DISPERSAL AND PREDATOR DENSITY-INDEPENDENT." Journal of Biological Systems 14, no. 04 (December 2006): 491–507. http://dx.doi.org/10.1142/s0218339006001933.
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In this paper, we study two-species predator–prey Lotka–Volterra-type dispersal system with periodic coefficients, in which the prey species can disperse among n-patches, but the predator species which is density-independent is confined to some patches and cannot disperse. By utilizing the analytic method, sufficient and realistic conditions on the boundedness, permanence, extinction, and the existence of positive periodic solution are established. The theoretical results are confirmed by a special example and numerical simulations.
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Hamilton, J. K., I. R. Hooper, and C. R. Lawrence. "Exploring microwave absorption by non-periodic metasurfaces." Advanced Electromagnetics 10, no. 3 (October 14, 2021): 1–6. http://dx.doi.org/10.7716/aem.v10i3.1803.
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In recent years there has been a large body of work investigating periodic metasurface microwave absorbers. However, surprisingly few investigations have focused on the absorption performance of similar non-periodic designs. In this work, the electromagnetic response of a large area (310 mm x 310 mm) microwave absorber that lacks a global periodicity is experimentally studied. The top metallic layer of the ultra-thin (0.3 mm) absorber is structured with rectangular patches given by a procedurally generated non-periodic pattern, known as the toothpick sequence. The specular reflectivity of both p-polarised and s-polarised incident radiation shows coupling to an additional low frequency mode when compared to a standard square patch periodic absorber. To further explore the coupling efficiency of such non-periodic absorbers, finite element models were used to investigate the influence of increasing sample size.
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Hamilton, J. K., I. R. Hooper, and C. R. Lawrence. "Exploring microwave absorption by non-periodic metasurfaces." Advanced Electromagnetics 10, no. 3 (October 14, 2021): 1–6. http://dx.doi.org/10.7716/aem.v10i3.1803.
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In recent years there has been a large body of work investigating periodic metasurface microwave absorbers. However, surprisingly few investigations have focused on the absorption performance of similar non-periodic designs. In this work, the electromagnetic response of a large area (310 mm x 310 mm) microwave absorber that lacks a global periodicity is experimentally studied. The top metallic layer of the ultra-thin (0.3 mm) absorber is structured with rectangular patches given by a procedurally generated non-periodic pattern, known as the toothpick sequence. The specular reflectivity of both p-polarised and s-polarised incident radiation shows coupling to an additional low frequency mode when compared to a standard square patch periodic absorber. To further explore the coupling efficiency of such non-periodic absorbers, finite element models were used to investigate the influence of increasing sample size.
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Lebon, Benoît, Jorge Peixinho, Shun Ishizaka, and Yuji Tasaka. "Subcritical transition to turbulence in a sudden circular pipe expansion." Journal of Fluid Mechanics 849 (June 18, 2018): 340–54. http://dx.doi.org/10.1017/jfm.2018.421.
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The results of experiments on the flow through a circular sudden expansion pipe at moderate Reynolds numbers are presented. At five diameters upstream of the expansion, laminar flow was disturbed by a (constant) cross-flow jet, a suction or a (periodic in–out) synthetic jet from a hole in the wall. When the disturbance exceeded a critical value of the control parameter depending on the Reynolds number, localised turbulent patches formed downstream of the expansion at fixed axial positions. For the cross-flow jet, the onset of turbulent patches is related to the velocity ratio of the mean jet velocity to the mean pipe velocity. At low velocity ratio, turbulent patches formed intermittently. For the suction disturbance, the flow experienced a strong asymmetry of the recirculation region and required a larger velocity ratio before the turbulent patch formed. For the synthetic jet, the amplification of wavy disturbances into turbulent patches and their axial positions are controlled by the driving frequency. Overall, these results suggest the existence of different mechanisms for the development of localised turbulent patches.
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LIU, ZIJIAN, ZHIDONG TENG, and LONG ZHANG. "TWO PATCHES IMPULSIVE DIFFUSION PERIODIC SINGLE-SPECIES LOGISTIC MODEL." International Journal of Biomathematics 03, no. 01 (March 2010): 127–41. http://dx.doi.org/10.1142/s1793524510000842.
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In this paper, we study a periodic single-species logistic system with impulsive diffusion in two patches. By using the iterative method, sufficient and necessary conditions on the existence, uniqueness and global attractivity of positive periodic solution and the extinction of species for this system are established. Two examples and numerical simulations are presented to illustrate the feasibility of our results.
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MARVÁ, M., J. C. POGGIALE, and R. BRAVO DE LA PARRA. "REDUCTION OF SLOW–FAST PERIODIC SYSTEMS WITH APPLICATIONS TO POPULATION DYNAMICS MODELS." Mathematical Models and Methods in Applied Sciences 22, no. 10 (August 13, 2012): 1250025. http://dx.doi.org/10.1142/s021820251250025x.
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This work deals with the approximate reduction of a nonautonomous two time scales ordinary differential equations system with periodic fast dynamics. We illustrate this technique with the analysis of two models belonging to different fields in ecology. On the one hand, we deal with a two patches periodic predator–prey model with a refuge for prey. Considering migrations between patches to be faster than local interaction allows us to study a three-dimensional system by means of a two-dimensional one. On the other hand, a two time scales periodic eco-epidemic model is addressed by considering two competing species, one of them being affected by a periodic SIR epidemic process which is faster than inter-species interactions. The difference between time scales allows us to study the asymptotic behavior of the four-dimensional system by means of a planar, reduced one. Furthermore, we propose a methodology straightforwardly applicable to a very large class of two time scales periodic systems.
Dissertations / Theses on the topic "Periodic patches"
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Maalik, Abdul. "Novel Characteristic-Mode-Based Synthesis and Analysis Method for Reflectarray Antennas." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1593684814222685.
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Almutawa, Ahmad Tariq. "Log-Periodic Microstrip Patch Antenna Miniaturization Using Artificial Magnetic Conductor Surfaces." Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/2982.
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Microstrip patch antennas are attractive for numerous military and commercial applications due to their advantages in terms of low-profile, broadside radiation, low-cost, low-weight and conformability. However, the inherent narrowband performance of patch antennas prohibits their use in systems that demand wideband radiation. To alleviate the issue, an existing approach is to combine multiple patch antennas within a log-periodic array configuration. These log-periodic patch antennas (LPMAs) are capable of providing large bandwidths (>50%) with stable broadside radiation patterns. However, they suffer from electrically large sizes. Therefore, their miniaturization without degrading the bandwidth performance holds promise for extending their use in applications that demand conformal and wideband installations.
In recent years, electromagnetic band gap structures have been proposed to enhance the radiation performances of printed antennas. These engineered surfaces consist of a periodic arrangement of unit cells having specific metallization patterns. At particular frequencies, they provide a zero-degree phase shift for reflected plane waves and effectively act as high impedance surfaces. Since, their band-limited electromagnetic field behavior is quite similar to a hypothetical magnetic conductor; they are also referred to as artificial magnetic conductors (AMCs). AMC structures were shown to allow lower antenna profile, larger bandwidth, higher gain, and good unidirectional radiation by alleviating the field cancellation effects observed in ground plane backed antenna configurations.
Previous research studies have already demonstrated that microstrip patch antennas can enjoy significant size reductions when placed above the AMC surfaces. This project, for the first time, investigates the application of AMCs to LPMA configurations. Specifically, the goal is to reduce the LPMA size while retaining its highly desired large bandwidth performance. To accomplish this, we employ various AMC surface configurations (e.g. uniform, log-periodic) under traditional LPMAs and investigate their performance in terms of miniaturization, bandwidth, gain, and radiation patterns.
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Chamblee, John Francis. "Landscape Patches, Macroregional Exchanges and pre-Columbian Political Economy in Southwestern Georgia." Diss., The University of Arizona, 2006. http://hdl.handle.net/10150/195436.
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Results from archaeological survey provide new insights into the origins of variation among the prehistoric Native American societies that occupied the Chickasawhatchee Swamp of southwestern Georgia. Through macroregional comparison, these insights are broadly applicable to the Eastern Woodlands societies that existed across the southeastern U.S. between A.D. 150 and 1600. Theoretical frameworks concerning landscape ecology, inter-regional exchange, and agency and structure provide the organizing structure for a multi-scalar view of change that contradicts earlier models.Within the Chickasawhatchee Swamp, survey, mapping, and excavation data present a complex regional settlement system. Within the swamp, a few large settlements were occupied for the long-term, in spite of the absence of monumental architecture. Smaller surrounding sites were periodically abandoned. At the swamp's edge, several subregions were organized around civic-ceremonial mound sites. At these edges, mound sites and surrounding subregions were abandoned simultaneously. Instead of being driven by changes in political complexity, residential mobility cycles were consistent through time and related to the region's heterogeneous landscape.Macroregional spatial data comparing mound locations through time support data from the Chickasawhatchee Swamp and confirm hypotheses relating mound construction and transitional landscapes. New data emphasize continuity in inter-regional exchange networks and contradict earlier views in which the emergence of hierarchical political structures were a transformational process that fundamentally altered Eastern Woodlands political economies. Temporal continuity and spatial variation are instead most evident.
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Musgrave, Jeffrey. "Integrodifference Equations in Patchy Landscapes." Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/26129.
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In this dissertation, we study integrodifference equations in patchy landscapes. Specifically, we provide a framework for linking individual dispersal behavior with population-level dynamics in patchy landscapes by integrating recent advances in modeling dispersal into an integrodifference equation.
First, we formulate a random-walk model in a patchy landscape with patch-dependent diffusion, settling, and mortality rates. We incorporate mechanisms for individual behavior at an interface which, in general, results in the probability-density function of the random walker being discontinuous at an interface. We show that the dispersal kernel can be characterized as the Green's function of a second-order differential operator and illustrate the kind of (discontinuous) dispersal kernels that arise from our approach. We examine the dependence of obtained kernels on model parameters.
Secondly, we analyze integrodifference equations in patchy landscapes equipped with discontinuous kernels. We obtain explicit formulae for the critical-domain-size problem, as well as, explicit formulae for the analogous critical size of good patches on an infinite, periodic, patchy landscape. We examine the dependence of obtained formulae on individual behavior at an interface. Through numerical simulations, we observe that, if the population can persist on an infinite, periodic, patchy landscape, its spatial profile can evolve into a discontinuous traveling periodic wave. We derive a dispersion relation for the speed of the wave and illustrate how interface behavior affects invasion speeds.
Lastly, we develop a strategic model for the spread of the emerald ash borer and its interaction with host trees. A thorough literature search provides point estimates and interval ranges for model parameters. Numerical simulations show that the spatial profile of an emerald ash borer invasion evolves into a pulse-like solution that moves with constant speed. We employ Latin hypercube sampling to obtain a plausible collection of parameter values and use a sensitivity analysis technique, partial rank correlation coefficients, to identify model parameters that have the greatest influence on obtained speeds. We illustrate the applicability of our framework by exploring the effectiveness of barrier zones on slowing the spread of the emerald ash borer invasion.
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Alqawasmeh, Yousef. "Models for Persistence and Spread of Structured Populations in Patchy Landscapes." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36845.
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In this dissertation, we are interested in the dynamics of spatially distributed populations. In particular, we focus on persistence conditions and minimal traveling
periodic wave speeds for stage-structured populations in heterogeneous landscapes.
The model includes structured populations of two age groups, juveniles and adults,
in patchy landscapes. First, we present a stage-structured population model, where we divide the population into pre-reproductive and reproductive stages. We assume that all parameters of the two age groups are piecewise constant functions in space. We derive explicit formulas for population persistence in a single-patch landscape and in heterogeneous habitats. We find the critical size of a single patch surrounded by a non-lethal matrix habitat. We derive the dispersion relation for the juveniles-adults model in homogeneous and heterogeneous landscapes. We illustrate our results by comparing the structured population model with an appropriately scaled unstructured model. We find that a long pre-reproductive state typically increases habitat requirements for persistence and decreases spatial spread rates, but we also identify scenarios in which a population with intermediate maturation rate spreads fastest. We apply sensitivity and elasticity formulas to the critical size of a single-patch landscape and to the minimal traveling wave speed in a homogeneous landscape.
Secondly, we use asymptotic techniques to find an explicit formula for the traveling
periodic wave speed and to calculate the spread rates for structured populations in
heterogeneous landscapes. We illustrate the power of the homogenization method by comparing the dispersion relation and the resulting minimal wave speeds for the
approximation and the exact expression. We find an excellent agreement between
the fully heterogeneous speed and the homogenized speed, even though the landscape period is on the same order as the diffusion coefficients and not as small as the formal derivation requires. We also generalize this work to the case of structured populations of n age groups.
Lastly, we use a finite difference method to explore the numerical solutions for the
juveniles-adults model. We compare numerical solutions to analytic solutions and
explore population dynamics in non-linear models, where the numerical solution for
the time-dependent problem converges to a steady state. We apply our theory to
study various aspects of marine protected areas (MPAs). We develop a model of
two age groups, juveniles and adults, in which only adults can be harvested and
only outside MPAs, and recruitment is density dependent and local inside MPAs and
fishing grounds. We include diffusion coefficients in density matching conditions at
interfaces between MPAs and fishing grounds, and examine the effect of fish mobility
and bias movement on yield and fish abundance. We find that when the bias towards
MPAs is strong or the difference in diffusion coefficients is large enough, the relative
density of adults inside versus outside MPAs increases with adult mobility. This
observation agrees with findings from empirical studies.
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Staffan, Paul. "Design of an ultra-wideband microstrip antenna array with low size, weight and power." Wright State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=wright1578437280799995.
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Marcello, Gregory James. "The Effects of Predation and Supplemental Food on Foraging and Abundance of White-Footed Mice (Peromyscus Leucopus) in Relation to Forest Patch Size." Oxford, Ohio : Miami University, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=miami1123179821.
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Cavalcanti, Liana Monique Paiva. "Oscilação intra e interanual na reprodução de uma comunidade de aves na Caatinga, um semiárido neotropical." Universidade Federal Rural do Semi-Árido, 2016. http://bdtd.ufersa.edu.br:80/tede/handle/tede/644.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
In semiarid regions, as the Caatinga, the rains distribution can determine the food availability and the intensity of hydric stress. This, with frequency, affects breeding aspects of birds, as time, length and reproduction intensity. In this study we have tested the hypothesis: (1) The breeding of the sampled species is restricted to the rainy season characteristic of the region; (2) Intra-annual variations in the rains’ volume and frequency are correlated with the quantity of individuals and species reproducing; (3) the species of the community reproducing in a way temporally jointly, independent of the feeding guilds. The study was accomplished in Caatinga’s region, with assessments every 14 days of brood patch occurrence. Three reproductive cycles was studied between september-2012 and october-2015. It was utilized the Cross-Correlation Function – CCF to verify the relation existing between the rains and the breeding birds. Altogether, 46 species (377 records) were observed with patches. The reproduction occurred in a seasonal way between february and july, with 94% of the records of patches restricted to the period. The intensity and duration of the breeding (total of individuals and species) was significantly correlated with the rains, when considered the time lag of 14 days. The length (140, 168, and 154 days) and time (march/02 to july/20, February/01 to july/19, February/12 to july/18) of breeding differed between three reproductive cycles. The analysis by feeding guild (insectivore-restrictive, insectivore-frugivorous, insectivore-granivorous and omnivorous) resulted in a similar pattern to general, mainly when it’s considered the correlation and time lag with the rains. Our study indicates that the breeding birds in the Caatinga’s area studied it was not just, generally, related to rainy seasons, as it was break out via answer of short deadline to the rainfall intensity. Including having it period, length and intensity regulated by this climatic factor or by other factors correlated to rains (g.e. food availability)
Em regiões semiáridas, como a Caatinga, a distribuição das chuvas pode determinar a disponibilidade do alimento e a intensidade do estresse hídrico. Isso, com frequência, afeta aspectos reprodutivos das aves, tais como época, comprimento e intensidade da reprodução. Neste estudo, testamos as hipóteses: (1) A reprodução das espécies amostradas é restrita ao período chuvoso característico da região; (2) variações intra-anuais no volume e na frequência das chuvas estão correlacionadas com a quantidade de indivíduos e espécies se reproduzindo; (3) as espécies da comunidade se reproduzem de forma temporalmente conjunta, independentemente da guilda alimentar. O estudo foi realizado em uma região de Caatinga, com avaliações a cada 14 dias de ocorrência de placa de incubação. Três ciclos reprodutivos foram estudados entre set-2012 e out-2015. Foi utilizada a Função de Correlação Cruzada (Cross-correlation Function – CCF) para verificar a existência de relação entre as chuvas e a reprodução das aves. Ao todo, 46 espécies (377 registros) foram observadas com placas. A reprodução ocorreu de forma sazonal entre fevereiro e julho, com 94% dos registros de placas restritos ao período. A intensidade e a duração da reprodução (total de indivíduos e de espécies) foram significativamente correlacionadas com as chuvas, quando considerado o time lag de 14 dias. O comprimento (140, 168 e 154 dias) e a época (02/mar a 20/jul, 01/fev a 19/jul, 13/fev a 18/jul) da reprodução diferiram entre os três ciclos reprodutivos. As análises por guilda alimentar (insetívoro-restritivo, insetívoro-frugívoro, insetívoro-granívoros e onívoros) resultaram em padrão semelhante ao geral, principalmente quando considerada a correlação e time lag com as chuvas. Nosso estudo indica que a reprodução das aves na área de Caatinga estudada não só esteve, de modo geral, relacionada às épocas chuvosas, como foi deflagrada via resposta de curto prazo à intensidade da precipitação. Inclusive, tendo seus períodos, comprimentos e intensidades regulados por este fator climático ou por outros fatores correlacionados às chuvas (e.g. disponibilidade de alimento)
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Alotaibi, Hammad Mayoof M. "Developing multiscale methodologies for computational fluid mechanics." Thesis, 2017. http://hdl.handle.net/2440/114544.
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The development of multiscale computational methods is a key research area in mathematics, physics, engineering and computer science. Engineers and scientists often perform detailed microscale computational simulations of a large scale complicated spatio-temporal system. For most problems of practical interest, there are two major complications in simulating the dynamical behaviour on large macroscopic space-time scales. The first is the often prohibitive computational cost when only a microscopic model is available. The second complication is the memory constraints which often make the simulation over the whole domain of interest infeasible. To overcome these obstacles, the equation-free approach was proposed by Keverkidis and colleagues in 2000. This approach is a multiscale method for capturing the behaviour on large scales of some complicated systems using only relatively small bursts of the microscale models. The patch dynamics scheme was proposed as an essential component of the equation-free framework. The patch scheme promises a great saving in computation time by predicting the macroscopic dynamics using detailed microscopic computation only on relatively small widely distributed patches of the spatial domain. This thesis provides mathematical analysis and computational simulation of some basic atom dynamics on small patches. The most significant novel result of this research is that patches with microscale periodic boundary conditions can be used to efficiently predict macroscale properties of interest. This result is important because microscale computations are often easiest with microscale periodic boundary conditions. As a major test of the approach, we analyse, implement and evaluate such a scheme for a computationally intensive atomistic simulation. Chapter 1 of this dissertation introduces the challenge of multiscale problems and highlights some recent developments of multiscale methods for complex systems. Chapter 2 explores atomistic simulations in three-dimensional space. The microscale atomistic simulator is used to predict a macroscale temperature field. This is achieved by performing atomistic simulation on a small triply-periodic patch. The method uses locally averaged properties over small space-time scales to advance and predict relatively large space scale dynamics. Our ultimate aim for this chapter is to explore the macroscopic properties of a system through atomistic simulation in small periodic patches, but as a pilot study this thesis only considers one small patch coupled over the macroscale to boundaries. The computation is implemented only on the periodic patch, while over most of the domain we interpolate in order to predict the macroscale temperature. The thesis develops appropriate control terms to the microscale action regions of the patch. The control is applied to the left and right action regions surrounding a core region. A proportional controller dependent upon the relatively distant boundaries enables reasonably accurate macroscale predictions. The analysis and computational simulations indicate that this innovative patch scheme empowers computation of large scale simulations of microscale systems. Chapter 3 analyses the case of a one-dimensional microscale diffusion system in a single microscale patch to predict the macroscale dynamics over a comparatively large spatial region. The nature of the solutions of the patch scheme is explored when operating with time-varying boundary conditions that mimic coupling with neighbouring, dynamically varying patches. The patch eigenfunctions and their adjoints form a biorthogonal basis to determine the spectral coefficients in formal series solutions. We also explore this patch scheme with time delays in the communication of boundary values. This models a patch when information from the neighbouring patches is subject to communication delays. The delayed patch scheme prediction is compared with a scheme without delays to delineate when such delays are significant. Chapter 4 analyses diffusion dynamics on multiple coupled patches. Centre manifold theory supports the patch scheme. The patch coupling conditions are standard Lagrange interpolation from the macroscale values at the centre of surrounding patches to the boundaries of each patch. The results of this chapter demonstrate the feasibility of the microscale patch scheme to model diffusion over large spatial scales. Chapter 5 extends the analysis to one-dimensional microscale advection-diffusion dynamics in a single patch and for multiple patches. Eigenvalue analysis suggests that a slow manifold exists on the macroscale. Computer algebra constructs the slow manifold model for the advection-diffusion dynamics. The long-time dynamics behaviour of numerical solutions on one patch is compared with the prediction of the slow manifold. Comparisons among the patch dynamics scheme, the microscale model over the complete domain, and published experimental data determines regimes where the patch dynamics accurately predicts the large scale advection-diffusion dynamics.Thesis (Ph.D.) -- University of Adelaide, School of Mathematical Sciences, 2017.
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Yu, Ming-Hong, and 余敏宏. "Loading Effects of Periodic Patch Array on a Coplanar Waveguide." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/86189055994393789301.
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碩士國立臺灣大學
電信工程學研究所
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An analysis of coplanar waveguide periodically loaded with crossing patches is presented. Floquet's theorm and the hybrid-mode spectral domain approach are used to obtain a set of coupled integral equations, and method of moments is used to transform the coupled integral equations into a determinantal equation from which the dispersion characteristics are obtained. Numerical results for the slow wave, leakage, radiation, and passband/stopband characteristics are presented.
Books on the topic "Periodic patches"
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MacKay, Glen, and Thomas D. Andrews. The Precontact History of Subarctic Northwest Canada. Edited by Max Friesen and Owen Mason. Oxford University Press, 2016. http://dx.doi.org/10.1093/oxfordhb/9780199766956.013.55.
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This chapter provides an overview of precontact hunter-gatherer land use in the Subarctic region of northwest Canada. The earliest evidence of human presence in this region is found in the unglaciated areas of Yukon Territory at Bluefish Caves and the Little John Site. The role of an ice-free corridor in the Mackenzie Valley in the dispersal of early peoples remains unclear. Caribou-hunting strategies are used as a theme to explore regional histories between 7,000 B.P. and the beginning of the historic period. Migratory tundra caribou were a focal resource for many hunter-gatherer societies in this region. The emerging archaeological record of alpine ice patches provides a unique view of hunter-gatherer land use in alpine regions. The archaeological record of the Mackenzie Valley is one of the poorest known in all of North America. Throughout, the chapter highlights the strengths and weaknesses of the Subarctic archaeological record for interpreting precontact land use.
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Abhishek, Abhishek, Adrian Jones, and Michael Doherty. Topical pharmacological treatments. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199668847.003.0028.
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Topical pharmacological agents such as non-steroidal anti-inflammatory drugs (NSAIDs) and capsaicin are widely recommended as first-line analgesics in the treatment of osteoarthritis (OA) of the knee, hand, and potentially other peripheral joints in view of their safety and efficacy. Although initial studies were short in duration (2–4 weeks), recent randomized controlled trials have confirmed the efficacy of topical NSAIDs over longer (12-week) study periods. Systematic reviews demonstrate that their efficacy can be equivalent to oral NSAIDs for OA pain, but they have a significantly better systemic toxicity profile than the corresponding oral formulations. Topical capsaicin is less well studied than topical NSAIDs but has been demonstrated to be effective in several placebo-controlled clinical trials. Local warming and an uncomfortable burning sensation is a common problem with initial applications, but this subsides with continued treatment and can be minimized by using a low-strength preparation (e.g. 0.025%) initially. Several other topical treatments such as drug-free transfersome gel and local lignocaine patches have been shown to be effective in controlling pain due to OA. However, they have been studied in relatively few studies and currently are not recommended for general use.
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Tunia, Krzysztof, ed. Kartki z dziejów igołomskiego powiśla. Wydawnictwo i Pracownia Archeologiczna PROFIL-ARCHEO, 2020. http://dx.doi.org/10.33547/igolomia2020.
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„Cards from the history of Igołomia region on the Vistula River” is a monumental, richly illustrated collective work devoted to the history of a patch of Małopolska (Lesser Poland; S Poland) located north-east of Kraków, in the Western Lesser Poland Loess Upland. This area is known to archaeologists for years as a kind of Eldorado, inhabited by subsequent human groups, ranging from Palaeolithic hunter-gatherers, through the shepherds of the Corded Ware culture, to the creators of the Igołomia-Zofipole wheel-trown pottery production center in the late Roman period. It played a significant role also in historical times, thanks to its location in the foreground of the capital of Małopolska. The monograph edited by Dr. Krzysztof Tunia, an archaeologist who has devoted most of his professional career to researching this region, reflects the current state of research on the prehistory and history of this part of the Vistula river. The advantage of the publication is the fact that the individual chapters come „first hand”: from the researchers who have conducted excavations, historical queries or anthropological studies here, and today synthesize their results in a form accessible to a wide audience. The reading is accompanied by the thought of longue durée – it is inevitable, in fact, when in one book one reads about the subsistence strategies of the first farmers from the 6th millennium BC, the innovations of their Slavic successors from the 6th century AD, the bias of local peasants toward the January Uprising or the attitude of the rural population in the face of the atrocities of the Holocaust…
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Tunia, Krzysztof, ed. Kartki z dziejów igołomskiego powiśla. 2nd ed. Wydawnictwo i Pracownia Archeologiczna Profil-Archeo, 2021. http://dx.doi.org/10.33547/igolomia2021.
Full textAbstract:
The second, supplemented edition of the „Cards from the history of Igołomia region on the Vistula River” is a monumental, richly illustrated collective work devoted to the history of a patch of Małopolska (Lesser Poland; S Poland) located north-east of Kraków, in the Western Lesser Poland Loess Upland. This area is known to archaeologists for years as a kind of Eldorado, inhabited by subsequent human groups, ranging from Palaeolithic hunter-gatherers, through the shepherds of the Corded Ware culture, to the creators of the Igołomia-Zofipole wheel-trown pottery production center in the late Roman period. It played a significant role also in historical times, thanks to its location in the foreground of the capital of Małopolska. The monograph edited by Dr. Krzysztof Tunia, an archaeologist who has devoted most of his professional career to researching this region, reflects the current state of research on the prehistory and history of this part of the Vistula river. The advantage of the publication is the fact that the individual chapters come „first hand”: from the researchers who have conducted excavations, historical queries or anthropological studies here, and today synthesize their results in a form accessible to a wide audience. The reading is accompanied by the thought of longue durée – it is inevitable, in fact, when in one book one reads about the subsistence strategies of the first farmers from the 6th millennium BC, the innovations of their Slavic successors from the 6th century AD, the attitude of local peasants toward the January Uprising or about daily life of the rural population in the dark times of the German occupation and atrocities of the Holocaust…
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UUelcome Matte©: Déltos from Link Starbureiy: an exercise of imagination, creativity, and wonder. online [weblog format]: The Link Egglepple Starbureiy Museum, 2010.
Find full textBook chapters on the topic "Periodic patches"
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Wang, Xiande, Douglas H. Werner, Jeremiah P. Turpin, and Pingjuan L. Werner. "Efficient Hybrid Algorithms for Characterizing 3-D Doubly Periodic Structures, Finite Periodic Microstrip Patch Arrays, and Aperiodic Tilings." In Computational Electromagnetics, 445–86. New York, NY: Springer New York, 2013. http://dx.doi.org/10.1007/978-1-4614-4382-7_12.
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Venkateshwar Rao, B., and Sunita Panda. "Design and Characterization of Microstrip Patch Antenna Using Octagonal EBG Periodic Structures." In Algorithms for Intelligent Systems, 489–96. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-1669-4_43.
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Halouzka, R., and F. Kováru. "Histology of the Continuous Peyer’s Patches in the Terminal Ileum of Pigs in the Perinatal Period." In Advances in Experimental Medicine and Biology, 399–401. Boston, MA: Springer US, 1995. http://dx.doi.org/10.1007/978-1-4615-1941-6_83.
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Panda, Ribhu Abhusan, Mihir Panda, Pawan Kumar Nayak, and Debasish Mishra. "Log Periodic Implementation of Butterfly Shaped Patch Antenna with Gain Enhancement Technique for X-Band Applications." In ICICCT 2019 – System Reliability, Quality Control, Safety, Maintenance and Management, 20–28. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-8461-5_3.
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Seibel, Wolfgang. "Intended Ignorance: The Collapse of the I-35 W Mississippi River Bridge on 1 August 2007." In Collapsing Structures and Public Mismanagement, 55–86. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-67818-0_3.
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AbstractAt 6:05 PM on 1 August 2007, the I-35 W Highway Bridge crossing the Mississippi River in Minneapolis, Minnesota, collapsed due to the failure of crucial parts of the bridge’s steel truss structure. Thirteen people died in the disaster, 145 were injured. A report of United States National Transportation Safety Board (NTSB) revealed that the Minnesota Department of Transport, over a long period of time, had ignored available information about the structurally deficient status of the bridge in anticipation of ‘budget busting’ repair costs. Which resulted in a preference for less expensive patch-up measures to improve the drivability of the bridge rather than a retrofit of the fracture-critical components of the steel truss whose failure triggered the disaster of 1 August 2007.
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De Giovanni, Nadia. "Sweat as an Alternative Biological Matrix." In Forensic Toxicology: Drug Use and Misuse, 438–63. The Royal Society of Chemistry, 2016. http://dx.doi.org/10.1039/bk9781782621560-00438.
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Situations with medico-legal implications, such as crime under the influence of alcohol/drugs, need the support of forensic toxicology. In order to identify drug use/abuse, toxicologists analyze biological specimens collected from corpses or living people. In the last decades, various specimens other than traditional blood and urine have been studied by researchers in order to support data obtained with conventional samples. Sweat is considered a suitable matrix with a peculiar time window of detection up to one week after intake; it can be collected by the means of patches that trap the xenobiotics released by sweat. Parent drugs are generally excreted at higher levels than metabolites, and the concentrations are expressed as nanograms/patch. It offers a non-invasive alternative for the monitoring of drugs exposure in living people as it can be collected for a programmed period with minimal disturbance for the individual. The main disadvantages of working with sweat are related to the amount of sample collected, which is variable and very low. The analysis of sweat may find applications in the monitoring of drug abuse as the patches provide a long-term detection of drug exposure. Forensic toxicology can benefit from sweat testing, for example in workplace drug testing or doping control.
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"Fish Habitat: Essential Fish Habitat and Rehabilitation." In Fish Habitat: Essential Fish Habitat and Rehabilitation, edited by Nina M. Kelly, Don Field, Ford A. Cross, and Robert Emmett. American Fisheries Society, 1999. http://dx.doi.org/10.47886/9781888569124.ch19.
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<em>Abstract.</em> —The rivers and streams that drain into the lower Columbia River estuary in Oregon contain essential fish habitat (EFH) for several species of Pacific salmon. Seven subwatershed basins in the Columbia River drainage basin, each containing salmon spawning and nursery habitat, were examined using remote sensing and geographic information system techniques to measure the amount and pattern of upland forest clearing. Landsat Thematic Mapper imagery from 1989 and 1992 was used to determine the cleared forest patches produced by clear-cutting. Digital Elevation Models were used to determine slope underlying cleared patches. A digital coverage (or map layer) of streams containing EFH was used to measure proximity of cleared patches to streams. The size and slope of cleared forest patches and the proximity of cleared forest patches to streams can greatly exacerbate the deposition of sediment in streams, altering stream environments and the quality of EFH. Size, slope, and proximity of cleared forest patches to streams containing EFH were calculated for the seven subwatershed basins. This analysis was performed at a landscape scale and utilized readily available broadscale data to (1) compare forest-clearing patterns across basins and (2) locate critical areas for further analysis using finer-scale data. Once critical areas had been located, a second analysis was performed using finer-scale data. The landscape-scale results indicated major differences in the spatial pattern of forest-clearing change across the lower Columbia River estuary drainage basin, with some subwatershed basins significantly altered in the three-year period. Three subwatershed basins showed a pattern of large cleared patches close to streams containing EFH. Some of these cleared forest patches were situated at least partially on steep slopes. In the three basins, Milton Creek, Young’s River, and the Claskanie River run directly through large areas of cleared forest. The pattern evidenced in these critical areas is consistent with increased sedimentation and decreased stream shading characteristics, both of which can have a detrimental effect on fish habitat. Milton Creek was examined with finer-scale data, and these results showed an increased number of cleared forest patches and increased total area of cleared forest draining into streams. More cleared forest patches on steep slopes were also shown with the finer-scale data. These results provide an initial justification for performing searches for critical areas at a synoptic or landscape scale, with further research performed at a finer scale. These techniques provide a practical method to evaluate upland land-use activities and essential fish habitat.
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"Fish Habitat: Essential Fish Habitat and Rehabilitation." In Fish Habitat: Essential Fish Habitat and Rehabilitation, edited by Nina M. Kelly, Don Field, Ford A. Cross, and Robert Emmett. American Fisheries Society, 1999. http://dx.doi.org/10.47886/9781888569124.ch19.
Full textAbstract:
<em>Abstract.</em> —The rivers and streams that drain into the lower Columbia River estuary in Oregon contain essential fish habitat (EFH) for several species of Pacific salmon. Seven subwatershed basins in the Columbia River drainage basin, each containing salmon spawning and nursery habitat, were examined using remote sensing and geographic information system techniques to measure the amount and pattern of upland forest clearing. Landsat Thematic Mapper imagery from 1989 and 1992 was used to determine the cleared forest patches produced by clear-cutting. Digital Elevation Models were used to determine slope underlying cleared patches. A digital coverage (or map layer) of streams containing EFH was used to measure proximity of cleared patches to streams. The size and slope of cleared forest patches and the proximity of cleared forest patches to streams can greatly exacerbate the deposition of sediment in streams, altering stream environments and the quality of EFH. Size, slope, and proximity of cleared forest patches to streams containing EFH were calculated for the seven subwatershed basins. This analysis was performed at a landscape scale and utilized readily available broadscale data to (1) compare forest-clearing patterns across basins and (2) locate critical areas for further analysis using finer-scale data. Once critical areas had been located, a second analysis was performed using finer-scale data. The landscape-scale results indicated major differences in the spatial pattern of forest-clearing change across the lower Columbia River estuary drainage basin, with some subwatershed basins significantly altered in the three-year period. Three subwatershed basins showed a pattern of large cleared patches close to streams containing EFH. Some of these cleared forest patches were situated at least partially on steep slopes. In the three basins, Milton Creek, Young’s River, and the Claskanie River run directly through large areas of cleared forest. The pattern evidenced in these critical areas is consistent with increased sedimentation and decreased stream shading characteristics, both of which can have a detrimental effect on fish habitat. Milton Creek was examined with finer-scale data, and these results showed an increased number of cleared forest patches and increased total area of cleared forest draining into streams. More cleared forest patches on steep slopes were also shown with the finer-scale data. These results provide an initial justification for performing searches for critical areas at a synoptic or landscape scale, with further research performed at a finer scale. These techniques provide a practical method to evaluate upland land-use activities and essential fish habitat.
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Lander, Brian. "The Nature of Political Power." In The King's Harvest, 14–31. Yale University Press, 2021. http://dx.doi.org/10.12987/yale/9780300255089.003.0002.
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This chapter illustrates the lives of ordinary people in four different periods in order to illustrate the changes that occurred over this time. It shows how agricultural systems improved over time, eventually becoming productive enough to create substantial and reliable surpluses. Political institutions gradually arose that used these surpluses to feed people doing nonagricultural labor, such as building infrastructure or fighting. The chapter discusses the village of Jiangzhai, near Xi'an, around 4500 BCE, which archaeologists call the Yangshao period and is situated in a grassy savanna with scattered patches of shrubs and woodlands. Human settlements are few and far between, and the landscape is home to dangerous animals like tigers and wild water buffaloes, perhaps one reason the village is surrounded by a deep ditch.
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Blevins, Brooks. "Domesticating the Ozarks." In A History of the Ozarks, Volume 1, 119–54. University of Illinois Press, 2018. http://dx.doi.org/10.5622/illinois/9780252041914.003.0005.
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Chapter 4 analyzes the taming or domesticating of the wilderness Ozarks by Anglo-American pioneers in the decades before the Civil War. This chapter discusses the effects of human habitation on the environment and on the region’s wildlife. It also covers such topics as hunting and trapping, log construction and material culture, rural folkways and foodways. A particular focus of the chapter is the introduction of an “extensive” style of agriculture in the Ozarks, one characterized by the raising of hogs and cattle on the open range and the growing of small patches of corn. By the end of the antebellum period, all but the most rugged and inaccessible areas of the Ozarks had undergone some degree of domestication.
Conference papers on the topic "Periodic patches"
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Beck, Benjamin S., Kenneth A. Cunefare, Massimo Ruzzene, and Manuel Collet. "Experimental Analysis of a Cantilever Beam With a Shunted Piezoelectric Periodic Array." In ASME 2010 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. ASMEDC, 2010. http://dx.doi.org/10.1115/smasis2010-3757.
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The use of both shunted piezoelectric elements and periodic arrays have been investigated independently as well as used in conjunction to modify the vibration of a system. Piezoelectric patches bonded to a cantilever beam which are shunted with an active circuit, specifically a negative capacitance shunt, can control broadband flexural vibrations of a structure. Also, periodic arrays integrated into a structure allow for modification of propagating waves through the mechanical “stop-bands”. The performance of a combined shunted periodic piezoelectric patch array will be analyzed here by investigating the velocity amplitude of the beam away from the array and in the array section, and the number of control elements in the array.
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Beck, Benjamin, Kenneth A. Cunefare, Massimo Ruzzene, and Manuel Collet. "Experimental Implementation of Negative Impedance Shunts on Periodic Structures." In ASME 2009 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. ASMEDC, 2009. http://dx.doi.org/10.1115/smasis2009-1369.
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Shunt damping of structures has been heavily researched, both passively and actively. Negative capacitance shunts actively control vibration on a structure and have been shown to obtain significant broadband suppression. The use of smaller piezoelectric patches, implemented in a periodic array, can alter the behavior of the control. Assorted shunt arrangements as well as circuit configurations will be investigated. Experimental results will be compared to theoretical predictions of shunt performance.
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Casadei, F., M. Ruzzene, B. Beck, and K. Cunefare. "Vibration control of plates featuring periodic arrays of hybrid shunted piezoelectric patches." In SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring, edited by Mehdi Ahmadian and Mehrdad N. Ghasemi-Nejhad. SPIE, 2009. http://dx.doi.org/10.1117/12.815843.
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Liu, Haixia, Fei Wang, Xiaowei Shi, and Long Li. "Ultra-wideband planar inverse-F antenna with periodic metal patches ground plane." In 2013 IEEE Third International Conference on Information Science and Technology (ICIST). IEEE, 2013. http://dx.doi.org/10.1109/icist.2013.6747744.
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Thorp, Owen G., Massimo Ruzzene, and Amr M. Baz. "Attenuation and localization of wave propagation in rods with periodic shunted piezoelectric patches." In SPIE's 8th Annual International Symposium on Smart Structures and Materials, edited by Daniel J. Inman. SPIE, 2001. http://dx.doi.org/10.1117/12.432706.
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Xia, Yiwei, Giuseppe Trainiti, Alper Erturk, and Massimo Ruzzene. "Selective Wave Filtering in Time-Modulated Elastic Metamaterials." In ASME 2018 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/detc2018-85991.
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We implement periodic stiffness time-modulation in a beam with piezoelectric patches and switchable shunted negative capacitance. The shunted negative capacitance circuits, connected in series with each piezoelectric patch through a switch, soften the structure. By alternatively opening and closing the switch, the beam’s stiffness effectively oscillates periodically between two values. We present a simplified theoretical model of time-periodic beams and describe the occurrence of flat bands in the dispersion diagrams. We show that a narrowband reflection from a time-modulated domain can be obtained for a broadband incident wave, hence qualifying the modulated domain as a single-port system with tunable response. We validate our theoretical findings by comparing time-domain simulations with experimental measurements of transient wavefields through scanning Doppler laser vibrometry.
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Svezhentsev, Alexander Ye, Vladimir Volski, and Guy A. E. Vandenbosch. "Plane Wave Scattering by Cylindrically Conformal Periodic Finite Array with PEC and Graphene Patches." In 2020 IEEE Ukrainian Microwave Week (UkrMW). IEEE, 2020. http://dx.doi.org/10.1109/ukrmw49653.2020.9252802.
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Lossouarn, Boris, Mathieu Aucejo, and Jean-François Deü. "Multimodal vibration damping through a periodic array of piezoelectric patches connected to a passive network." In SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring, edited by Wei-Hsin Liao. SPIE, 2015. http://dx.doi.org/10.1117/12.2083835.
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Bozzi, M., M. Montagna, and L. Perregrini. "Modeling of printed periodic structures with thick metal patches by the MoM/BI-RME method." In 2010 IEEE/MTT-S International Microwave Symposium - MTT 2010. IEEE, 2010. http://dx.doi.org/10.1109/mwsym.2010.5515052.
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Bozzi, Maurizio, Maria Montagna, and Luca Perregrini. "Modeling of printed periodic structures with thick metal patches by the MoM/BI-RME method." In 2010 IEEE/MTT-S International Microwave Symposium - MTT 2010. IEEE, 2010. http://dx.doi.org/10.1109/mwsym.2010.5518166.
Full textReports on the topic "Periodic patches"
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Perkins, Dustin. Invasive exotic plant monitoring at Colorado National Monument: 2019 field season. Edited by Alice Wondrak Biel. National Park Service, July 2021. http://dx.doi.org/10.36967/nrr-2286650.
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Invasive exotic plant (IEP) species are a significant threat to natural ecosystem integrity and biodiversity, and controlling them is a high priority for the National Park Service. The North-ern Colorado Plateau Network (NCPN) selected the early detection of IEPs as one of 11 monitoring protocols to be implemented as part of its long-term monitoring program. This report represents work completed at Colorado National Monument during 2019. During monitoring conducted June 12–19, a total of 20 IEP species were detected on monitoring routes and transects. Of these, 12 were priority species that accounted for 791 separate IEP patches. IEPs were most prevalent along riparian areas. Yellow sweetclover (Melilotis officinale) and yellow salsify (Tragopogon dubius) were the most commonly detected priority IEPs along monitoring routes, representing 73% of all priority patches. Patches of less than 40 m2 were typical of nearly all priority IEP species except yellow sweetclover. A patch management index (PMI) was created by combining patch size class and percent cover for each patch. In 2019, a large majority of priority IEP patches were assigned a PMI score of low (46%) or very low (50%), indicating small and/or sparse patches where control is generally still feasible. This is similar to the numbers for 2017, when 99% of patches scored low or very low in PMI. Seventy-eight percent of tree patches were classified as seedlings or saplings, which require less effort to control than mature trees. Cheatgrass (Anisantha tectorum) was the most common IEP recorded in transects, found in 30–77% of transects across the different routes. It was the only species found in transects on all monitoring routes. When treated and untreated extra areas near the West Entrance were compared, the treated area had comparable or higher lev-els of IEPs than the untreated area. When segments of monitoring routes conducted between 2003 and 2019 were compared, results were mixed, due to the different species monitored in different time periods. But in general, the number of IEPs per 100 meters is increasing or remaining constant over time. There were notable increases in IEP patches per 100 meters on several routes in 2019: field bindweed (Convolvulus arvensis) along East Glade Park Road; Siberian elm (Ulmus pumila) in Red Canyon; yellow salsify along East Glade Park Road, No Thoroughfare Canyon, No Thoroughfare Trail, and Red Canyon; and yellow sweetclover in No Thoroughfare Canyon and Red Canyon. Network staff will return to re-sample monitoring routes in 2021.
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Perkins, Dustin. Invasive exotic plant monitoring at Colorado National Monument: 2021 field season. Edited by Alice Wondrak Biel. National Park Service, September 2022. http://dx.doi.org/10.36967/2294260.
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Invasive exotic plant (IEP) species are a significant threat to natural ecosystem integrity and biodiversity, and controlling them is a high priority for the National Park Service. The Northern Colorado Plateau Network (NCPN) selected the early detection of IEPs as one of 11 monitoring protocols to be implemented as part of its long-term monitoring program. This report represents work completed at Colorado National Monument during 2021. During monitoring conducted June 9–15, a total of 15 priority IEP species in 395 patches were detected on 53.6 kilometers (33.3 mi) of monitoring routes. An additional four species were detected in transects. Yellow salsify (Tragopogon dubius), ripgut brome (Anisantha diandra), jointed goatgrass (Cylindropyrum cylindricum), and tamarisk (Tamarix sp.) were the most commonly detected priority IEPs along monitoring routes, representing 74% of all priority patches. Except for ripgut brome and broad-leaf pepperwort (Cardaria latifolia), most patches of priority IEPs were than 40 m2. Ninety-five percent of tree patches were classified as seedlings or saplings, which require less effort to control than mature trees. Cheatgrass (Anisantha tectorum) was the most common IEP in transects, found in >63% of transects along every route surveyed. When segments of monitoring routes consistently surveyed from 2005 to 2021 were analyzed, Red Canyon, Wedding Canyon, and Fruita Canyon all had the highest number of IEPs per 100 meters during the entire monitoring period. Increases were driven by increases in jointed goatgrass on all three routes and yellow salsify (Tragopogon dubius) in Wedding Canyon and tamarisk in Red Canyon. Jointed goatgrass appears to be rapidly expanding, increasing from 8 patches in 2019 to 42 patches in 2021 (though the routes surveyed were not all the same). In addition, three species not seen in recent years—Canada thistle (Breea arvensis), bull thistle (Cirsium vulgare), and broad-leaf pepperwort—were detected, but in fewer than 10 patches each. These species should be prioritized for control. The No Thoroughfare, Ute Canyon, and Monument Canyon routes all have stayed relatively stable over time, but at least one patch of jointed goatgrass was found on each. Network staff plans to return to re-sample monitoring routes in 2023.
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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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Short, Mary, and Sherry Leis. Vegetation monitoring in the Manley Woods unit at Wilson’s Creek National Battlefield: 1998–2020. Edited by Tani Hubbard. National Park Service, June 2022. http://dx.doi.org/10.36967/nrr-2293615.
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Natural resource management at Wilson’s Creek National Battlefield (NB) is guided by our understanding of the woodlands and prairies at the time of the Civil War battle in 1861. This report is focused on the Manley Woods unit of the park. This unit is an oak-hickory woodland in the Springfield Plain subsection of the Ozarks. Canopy closure for Missouri oak woodlands can be highly variable and ranges from 30–100% across the spectrum of savanna, open woodland, and closed woodland types. In 1861, the woodland was likely a savanna community. Changes in land use (e.g., fire exclusion) caused an increase in tree density in woodlands at Wilson’s Creek NB and across the Ozarks. Savannas and open woodlands transitioned to closed canopy woodlands over time. Park management plans include restoring the area to a savanna/open woodland structure. Prescribed fire was reintroduced to Wilson’s Creek NB in 1988 and continues as the primary mechanism for reducing the tree canopy. The Manley Woods unit of Wilson’s Creek NB has been subject to intense natural and anthropogenic disturbance events such as a tornado in 2003, timber removal in 2005, prescribed fires in 2006, 2009, and 2019, an ice storm in 2007, and periodic drought. The Heartland Inventory and Monitoring Network (hereafter, Heartland Network) installed four permanent monitoring sites within the Manley Woods area of the park in 1997. Initially, we assessed ground flora and regeneration within the sites (1998–1999). We added fuel sampling after the 2003 tornado. Although overstory sampling occurred prior to the tornado, the protocol was not yet stabilized and pre-2003 overstory data were not included in these analyses. In this report, we focus on the overstory, tree regeneration, and ground cover metrics; ground flora data will be assessed in future analyses. Heartland Network monitoring data reveal that Manley Woods has undergone substantial change in canopy cover and midstory trees since 1998. While basal area and density metrics classify Manley Woods as an open woodland, the closed canopy of the midstory and overstory reveal a plant community that is moving toward closed woodland or forest structure. The most recent fire in 2019 was patchy and mild, resulting in continued increases in fuels. Ground cover metrics indicate infrequent disturbance since leaf litter continued to increase. Management objectives to restore savanna or woodland composition and structure to the Manley Woods overstory, regeneration layer, and ground cover will require implementation of prescribed fire in the future. Repeated fires can thin midstory trees and limit less fire tolerant early seral species. Additionally, mechanical or chemical treatments to reduce undesirable tree species should be considered for woodland restoration. Decreasing canopy closure is an important and essential step toward the restoration of a functioning savanna/open woodland plant community in Manley Woods. Treatments that thin the midstory and reduce fuel loading will also benefit these plant communities. With the anticipated changing climate, maintaining an open woodland community type may also provide resilience through management for native species tolerant of increasingly warmer temperatures.