To see the other types of publications on this topic, follow the link: Spatial and temporal partitioning.
Dissertations / Theses on the topic 'Spatial and temporal partitioning'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Spatial and temporal partitioning.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Thorgeirsson, Halldor. "Temporal and spatial partitioning of the soil water resource between two Agropyron bunchgrasses and Artemisia tridentata." DigitalCommons@USU, 1985. https://digitalcommons.usu.edu/etd/6439.
Full textAbstract:
Dynamics of soil water use by two cool-season Agropyron bunchgrasses during the warm season depletion of soil water reserves were monitored for two years in experimental plots in the field. Agropyron desertorum, an introduced, competitive species from Eurasia, extracted more water from the deeper ( > 50 cm) soil layers than the native, less competitive Agropyron spicatum. Agropyron desertorum both extracts this water earlier and to lower soil water potentials than Agropyron spicatum. From the water extraction dynamics of the grasses in monocultures and in their two-way (50:50) mixtures with a shrub they commonly co-occur with, Artemisia tridentata, partitioning of the soil water resource between the grasses and the shrub was inferred. This indicated that Artemisia tridentata and Agropyron desertorum partitioned the soil water resource fairly evenly, while considerable quantities of water in the deeper soil layers under Agropyron spicatum seemed to be available to the shrub without direct competition. The implications of this difference in water resource partitioning for competition of the grasses with Artemisia tridentata are discussed. Predawn and midday xylem pressure potentials were not different between the two grasses in spite of different fluxes through the plants. Agropyron desertorum initiated new adventitious roots in fall and early spring while Agropyron spicatum did so only during spring. Observations from a root observation chamber indicated essentially parallel pattern of lateral root elongation during the depletion phase through top 200 cm of the profile. In both species the number of active tips, and the rate of elongation of active tips, decreased as the soil dried out. Root tips at all depths were inactive by the middle of September. Agropyron desertorum maintained root elongation at 50-110 cm for two weeks longer than A. spicatum.
2
Hall, Lucas Keith. "Competition Dynamics Within Communities of Desert Wildlife at Water Sources." BYU ScholarsArchive, 2016. https://scholarsarchive.byu.edu/etd/6402.
Full textAbstract:
Water is a vital resource for species inhabiting arid and semi-arid regions and can shape the biotic communities that we observe. Because water is considered a limiting resource for many species in desert environments, there is the potential for competitive interactions between species to occur at or around water sources. For this dissertation I tested hypotheses related to resource competition among different species of wildlife in the Great Basin and Mojave Deserts of western Utah. Chapter one evaluated the influence of feral horses (Equus caballus) on patterns of water use by communities of native birds and mammals. Chapter two determined if feral horses competed with pronghorn (Antilocapra americana) and mule deer (Odocoileus hemionus) for access to water. In chapters one and two, we found evidence that horses compete with native wildlife for water. In chapter one, horses were associated with decreased richness and diversity of native species at water sources. Native species also had fewer visits and spent less time at water sources frequented by horses. In chapter two, we found that pronghorn and mule deer used water sources less often where horse activity was high. There were also significant differences in temporal activity for pronghorn, but not mule deer, at horse-occupied sites versus sites where horses were absent or uncommon. Our results indicated that horses spatially and temporally displaced other species at water sources providing evidence of a negative influence on how communities of native wildlife access a limited resource in an arid environment. Chapter three assessed whether dominant carnivores (coyote (Canis latrans) and bobcat (Lynx rufus)) negatively influenced the spatial use of water sources by the subordinate kit fox (Vulpes macrotis). Our results did not reveal strong negative associations between kit fox visits to water sources and visits by dominant carnivores; in fact, dominant carnivores contributed very little to the use of water by kit foxes. Instead, kit fox visits were more closely associated with habitat features at water sources. Our findings indicate that dominant carnivores are not the primary driver of use of water sources by subordinate carnivores. Chapter four evaluated whether a simulated loss of water due to climate change/increased human use would differentially affect desert bats based on flight morphology and maneuverability. When we experimentally reduced surface area of water sources, larger, less-maneuverable bats experienced a 69% decrease in drinking success and increased competition with smaller, maneuverable bats. Anticipated reductions in the sizes of water sources due to climate change may lead to species with less maneuverability being unable to access water efficiently and facing increased competition from more agile bats.
3
Sorribas, Mellado Juan José. "Biological control of California red scale, Aonidiella aurantii (Hemiptera: Diaspididae): spatial and temporal distribution of natural enemies, parasitism levels and climate effects." Doctoral thesis, Universitat Politècnica de València, 2012. http://hdl.handle.net/10251/14794.
Full textAbstract:
En muchas áreas citrícolas del mundo el piojo rojo de California (PRC), Aonidiella aurantii (Hemiptera: Diaspididae), está considerado una plaga clave. En el Este de España se ha extendido durante las últimas décadas hasta cubrir una amplia extensión de cítricos. El control químico es difícil y frecuentemente es seguido de infestaciones recurrentes en poco tiempo, de la aparición de resistencias a diferentes productos usados para su control y de la eliminación de enemigos naturales en el campo. La mejora del manejo
integrado y las técnicas de control biológico del PRC requieren conocer la composición de los enemigos naturales en cada zona climática, la fluctuación en su abundancia estacional, los niveles de parasitismo y depredación, como se distribuyen en la planta y como son afectados por el clima y el cambio climático.
Aunque mucho se ha estudiado en laboratorio sobre los parasitoides Aphytis (Hymenoptera: Aphelinidae), los principales agentes de control del PRC, todavía no se conoce qué combinación de enemigos naturales consigue el mejor nivel de control en el campo, cómo varían los niveles de parasitismo a lo largo del año o cómo los parasitoides se distribuyen y compiten en el campo en relación con el clima. La acción de los Aphytis, ectoparasitoides, es complementada en muchas zonas citrícolas por los endoparasitoides
Comperiella bifasciata y Encarsia perniciosi (Hymenoptera: Aphelinidae), los cuales pueden parasitar estadíos diferentes a Aphytis. Muy poco se sabe sobre el comportamiento y las respuestas biológicas bajo diferentes condiciones climáticas de estos endoparasitoides. Del mismo modo, el efecto de los depredadores sobre la población del piojo ha sido raramente estudiado. Actualmente, A. melinus, una especie introducida en el Este de España y el competidor superior, ha desplazado al parasitoide nativo A. chrysomphali de las zonas cálidas y secas ya que puede tolerar mejor las temperaturas cálidas del verano.Sorribas Mellado, JJ. (2011). Biological control of California red scale, Aonidiella aurantii (Hemiptera: Diaspididae): spatial and temporal distribution of natural enemies, parasitism levels and climate effects [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/14794
Palancia
4
Cebecauer, Matej. "Short-Term Traffic Prediction in Large-Scale Urban Networks." Licentiate thesis, KTH, Transportplanering, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-250650.
Full textAbstract:
City-wide travel time prediction in real-time is an important enabler for efficient use of the road network. It can be used in traveler information to enable more efficient routing of individual vehicles as well as decision support for traffic management applications such as directed information campaigns or incident management. 3D speed maps have been shown to be a promising methodology for revealing day-to-day regularities of city-level travel times and possibly also for short-term prediction. In this paper, we aim to further evaluate and benchmark the use of 3D speed maps for short-term travel time prediction and to enable scenario-based evaluation of traffic management actions we also evaluate the framework for traffic flow prediction. The 3D speed map methodology is adapted to short-term prediction and benchmarked against historical mean as well as against Probabilistic Principal Component Analysis (PPCA). The benchmarking and analysis are made using one year of travel time and traffic flow data for the city of Stockholm, Sweden. The result of the case study shows very promising results of the 3D speed map methodology for short-term prediction of both travel times and traffic flows. The modified version of the 3D speed map prediction outperforms the historical mean prediction as well as the PPCA method. Further work includes an extended evaluation of the method for different conditions in terms of underlying sensor infrastructure, preprocessing and spatio-temporal aggregation as well as benchmarking against other prediction methods.QC 20190531
5
Indrakanti, Saratchandra. "Computational Methods for Vulnerability Analysis and Resource Allocation in Public Health Emergencies." Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc804902/.
Full textAbstract:
POD (Point of Dispensing)-based emergency response plans involving mass prophylaxis may seem feasible when considering the choice of dispensing points within a region, overall population density, and estimated traffic demands. However, the plan may fail to serve particular vulnerable sub-populations, resulting in access disparities during emergency response. Federal authorities emphasize on the need to identify sub-populations that cannot avail regular services during an emergency due to their special needs to ensure effective response. Vulnerable individuals require the targeted allocation of appropriate resources to serve their special needs. Devising schemes to address the needs of vulnerable sub-populations is essential for the effectiveness of response plans. This research focuses on data-driven computational methods to quantify and address vulnerabilities in response plans that require the allocation of targeted resources. Data-driven methods to identify and quantify vulnerabilities in response plans are developed as part of this research. Addressing vulnerabilities requires the targeted allocation of appropriate resources to PODs. The problem of resource allocation to PODs during public health emergencies is introduced and the variants of the resource allocation problem such as the spatial allocation, spatio-temporal allocation and optimal resource subset variants are formulated. Generating optimal resource allocation and scheduling solutions can be computationally hard problems. The application of metaheuristic techniques to find near-optimal solutions to the resource allocation problem in response plans is investigated. A vulnerability analysis and resource allocation framework that facilitates the demographic analysis of population data in the context of response plans, and the optimal allocation of resources with respect to the analysis are described.
6
Zabos, Attila. "Temporal partitioning of flexible real-time systems." Thesis, University of York, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.547350.
Full text
7
DEEPAK, MEKARAJ V. "A FLEXIBLE FRAMEWORK FOR OPTIMIZED TEMPORAL PARTITIONING." University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin980256309.
Full text
8
Parker, Austin. "Spatial probabilistic temporal databases." College Park, Md.: University of Maryland, 2008. http://hdl.handle.net/1903/8728.
Full textAbstract:
Thesis (Ph. D.) -- University of Maryland, College Park, 2008.Thesis research directed by: Dept. of Computer Science. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
9
Bobda, Christophe. "Synthesis of dataflow graphs for reconfigurable systems using temporal partitioning and temporal placement." [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=968530567.
Full text
10
Riordan, Philip. "Spatial and resource partitioning in mammalian carnivore assemblages." Thesis, Manchester Metropolitan University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.392983.
Full text
11
Gwalani, Harsha. "Spatial Partitioning Algorithms for Solving Location-Allocation Problems." Thesis, University of North Texas, 2019. https://digital.library.unt.edu/ark:/67531/metadc1609062/.
Full textAbstract:
This dissertation presents spatial partitioning algorithms to solve location-allocation problems. Location-allocations problems pertain to both the selection of facilities to serve demand at demand points and the assignment of demand points to the selected or known facilities. In the first part of this dissertation, we focus on the well known and well-researched location-allocation problem, the "p-median problem", which is a distance-based location-allocation problem that involves selection and allocation of p facilities for n demand points. We evaluate the performance of existing p-median heuristic algorithms and investigate the impact of the scale of the problem, and the spatial distribution of demand points on the performance of these algorithms. Based on the results from this comparative study, we present guidelines for location analysts to aid them in selecting the best heuristic and corresponding parameters depending on the problem at hand. Additionally, we found that existing heuristic algorithms are not suitable for solving large-scale p-median problems in a reasonable amount of time. We present a density-based decomposition methodology to solve large-scale p-median problems efficiently. This algorithm identifies dense clusters in the region and uses a MapReduce procedure to select facilities in the clustered regions independently and combine the solutions from the subproblems. Lastly, we present a novel greedy heuristic algorithm to solve the contiguity constrained fixed facility demand distribution problem. The objective of this problem is to create contiguous service areas for the facilities such that the demand at all facilities is uniform or proportional to the available resources, while the distance between demand points and facilities is minimized. The results in this research are shown in the context of creating emergency response plans for bio-emergencies. The algorithms are used to select Point of Dispensing (POD) locations (if not known) and map them to population regions to ensure that all affected individuals are assigned to a POD facility.
12
Storey, Susan. "Spatial-temporal fish stock assessment." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ28463.pdf.
Full text
13
Slack, Marc G. "Spatial and temporal path planning." Thesis, This resource online, 1987. http://scholar.lib.vt.edu/theses/available/etd-04272010-020255/.
Full text
14
Liu, Fang 1962. "Modeling spatial and temporal textures." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/29131.
Full text
15
Henderson, Jonathan. "Avian spatial and temporal cognition." Thesis, University of Edinburgh, 2004. http://hdl.handle.net/1842/14049.
Full textAbstract:
I investigated the spatial memory abilities of male rufous hummingbirds (Selasphorus rufus) on their breeding grounds, where birds can be readily trained to feed from artificial flowers presented in two- and three-dimensional arrays. I found that birds use height as a cue when encoding flower locations, preferring to visit taller flowers. Performance in three-dimensional arrays was not however consistently better than in 2-D arrays. I also examined the possibility that hummingbirds follow a fixed flight path when returning to an array of flowers, as has been seen in the Hymenoptera. By manipulating the number of doors by which a bird could enter an arena to feed on an array of flowers, I found some evidence that birds do use systematic movements when relocating rewarding sites. Rufous hummingbirds feed on floral nectar, a resource that varies in time as well as space. To determine whether these birds use time as a cue when foraging, I provided them with an array in which flowers were refilled after intervals of either ten or twenty minute. The birds were able to learn these intervals, as they returned to flowers on or shortly after their expected refill time. I used an analogous experiment to investigate timing abilities in coal tits (Parus ater), a food-storing species, and great tits (P. major), a non food-storing species, in the laboratory. Storers and non-storer might differ in their ability to time intervals due to the demands, on storers, of reliable cache recovery. Coal tits were able to track the availability of rewards in three different locations associated with reward schedules in the 30-120s range. I found no consistent differnces in the abilities of coal tits and great tits to time intervals in the 40-70s range. In conclusion, rufous hummingbirds were shown to use both spatial and temporal cues whilst foraging at flowers. Coal tits and great tits were able to time short intervals in the laboratory, but I found no overall differences in timing behaviour between the two species.
16
Kratz, Jakob, and Viktor Luthman. "Comparison of spatial partitioning data structures in crowd simulations." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-302340.
Full textAbstract:
This report investigates how the construction and query time of multiple spatial partitioning data structures is impacted by spatial distribution of and number of agents in a crowd simulation. In addition a method is investigated for updating the data structures less frequently at the cost of increasing the radius queried, without affecting the correctness of the queries. The data structures are tested in a simulation using a Boids model and update and query times are measured. It is found that the performance of the grid is better than the quad tree and the kd- tree for low number of agents, but deteriorates more quickly when the number of agents increase. It is also found that this approach can decrease the sum of time spent updating and the time spent querying in the simulation. The effectiveness of this method is highly dependent on the update of the data structure.Denna rapport undersöker hur konstruktion och grannsökning av flera datastrukturer för spatial partitionering påverkas av spatial fördelning av simuleringens agenter och antal agenter i simuleringen. Dessutom undersöks en metod för att uppdatera datastrukturerna mindre ofta, på bekostnad av att utöka grannsökningens radie, utan att påverka grannsökningens korrekthet. Datastrukturerna testas i en simulering baserad på Boids och uppdaterings- och frågetider för datastrukturerna mäts. Det visar sig att prestandan av grid är bättre än prestandan av quad tree och kd- tree för ett litet antal agenter, men att prestandan för grid försämras snabbare när antalet agenter ökar. Dessutom visar sig denna metod kunna ge en minskning i den totala tiden som går åt till att göra grannsökningar och uppdateringar av datastrukturen. Hur effektiv denna metod är beror i hög grad på hur lång uppdateringstiden är för den använda datastrukturen.
17
Zhou, Feng. "Spatial, Temporal and Spatio-Temporal Correspondence for Computer Vision Problems." Research Showcase @ CMU, 2014. http://repository.cmu.edu/dissertations/410.
Full textAbstract:
Many computer vision problems, such as object classification, motion estimation or shape registration rely on solving the correspondence problem. Existing algorithms to solve spatial or temporal correspondence problems are usually NP-hard, difficult to approximate, lack flexible models and mechanism for feature weighting. This proposal addresses the correspondence problem in computer vision, and proposes two new spatio-temporal correspondence problems and three algorithms to solve spatial, temporal and spatio-temporal matching between video and other sources. The main contributions of the thesis are: (1) Factorial graph matching (FGM). FGM extends existing work on graph matching (GM) by finding an exact factorization of the affinity matrix. Four are the benefits that follow from this factorization: (a) There is no need to compute the costly (in space and time) pairwise affinity matrix; (b) It provides a unified framework that reveals commonalities and differences between GM methods. Moreover, the factorization provides a clean connection with other matching algorithms such as iterative closest point; (c) The factorization allows the use of a path-following optimization algorithm, that leads to improved optimization strategies and matching performance; (d) Given the factorization, it becomes straight-forward to incorporate geometric transformations (rigid and non-rigid) to the GM problem. (2) Canonical time warping (CTW). CTW is a technique to temporally align multiple multi-dimensional and multi-modal time series. CTW extends DTW by incorporating a feature weighting layer to adapt different modalities, allowing a more flexible warping as combination of monotonic functions, and has linear complexity (unlike DTW that has quadratic). We applied CTW to align human motion captured with different sensors (e.g., audio, video, accelerometers). (3) Spatio-temporal matching (STM). Given a video and a 3D motion capture model, STM finds the correspondence between subsets of video trajectories and the motion capture model. STM is efficiently and robustly solved using linear programming. We illustrate the performance of STM on the problem of human detection in video, and show how STM achieves state-of-the-art performance.
18
Axel, Lindegren. "Partitioning temporal networks : A study of finding the optimal partition of temporal networks using community detection." Thesis, Uppsala universitet, Avdelningen för datalogi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-350263.
Full textAbstract:
Many of the algorithms used for community detection in temporal networks have been adapted from static network theory. A common approach in dealing with the temporal dimension is to create multiple static networks from one temporal, based on a time condition. In this thesis, focus lies on identifying the optimal partitioning of a few temporal networks. This is done by utilizing the popular community detection algorithm called Generalized Louvain. Output of the Generalized Louvain comes in two parts. First, the created community structure, i.e. how the network is connected. Secondly, a measure called modularity, which is a scalar value representing the quality of the identified community structure. The methodology used is aimed at creating a comparable result by normalizing modularity. The normalization process can be explained in two major steps: 1) study the effects on modularity when partitioning a temporal network in an increasing number of slices. 2) study the effects on modularity when varying the number of connections (edges) in each time slice. The results show that the created methodology yields comparable results on two out of the four here tested temporal networks, implying that it might be more suited for some networks than others. This can serve as an indication that there does not exist a general model for community detection in temporal networks. Instead, the type of network is key to choosing the method.
19
Bai, Ping Truong Young K. Smith Richard L. "Temporal-spatial modeling for fMRI data." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2007. http://dc.lib.unc.edu/u?/etd,1481.
Full textAbstract:
Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2007.Title from electronic title page (viewed Apr. 25, 2008). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Statistics and Operations Research." Discipline: Statistics and Operations Research; Department/School: Statistics and Operations Research.
20
Bonsall, Michael B. "Temporal and spatial insect population dynamics." Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.406839.
Full text
21
Liddle, Elizabeth B. "Temporal and spatial attention in dyslexia." Thesis, University of Nottingham, 2006. http://eprints.nottingham.ac.uk/14422/.
Full textAbstract:
It was hypothesized that the deficits underlying reading impairment may arise from supra-modal deficits in temporal and spatial attention, disrupting, on the one hand, the ability to segment the temporally ordered phonemes of language and thus the acquisition of decoding skills, and, on the other, the ability to integrate spatially and temporally ordered orthographic information acquired from the fluent visual scanning of written text. Temporal and spatial attentional deficits in dyslexia were investigated using a lateralized visual temporal order judgment (TOJ) paradigm that allowed both sensitivity to temporal order and spatial attentional bias to be measured. Dyslexic and non-dyslexic participants were required to report the temporal order of two simple visual stimuli presented in either the same or different lateral hemifields. Findings indicated that dyslexic participants showed markedly impaired sensitivity to temporal order, and that the degree of impairment was correlated with the severity of their dyslexia. Furthermore, the findings suggested that at least three partially dissociated deficits may underlie both impaired TOJ task performance and reading disorder. One is a deficit associated with difficulty in reporting the temporal order of two visual stimuli, particularly when the first is presented in right hemifield; with slow word recognition and non-word reading; and with deficits in spelling and phonological skill. This constellation of deficits was interpreted as reflecting deficits in networks in left cerebral hemisphere implicated in phoneme-grapheme mapping and visual orienting. The second is a deficit that is associated with a rightward attentional bias; with inaccurate non-word reading that is worse than predicted by phonological skill or by word recognition; and with poor sustained attention. This constellation of impairments was interpreted as evidence of a deficit in right-lateralised networks implicated in the modulation of arousal, and possibly reflecting a “developmental left-neglect” syndrome. A third deficit was associated with impaired temporal order sensitivity, regardless of hemifield presentation; with symptoms of Attentional Deficit and Hyperactivity Disorder (ADHD); and with increased interference from distractor stimuli. This constellation of deficits suggests that the impaired network is implicated in executive control of attention, including conflict resolution and working memory. The results of the investigation as a whole suggests that the reading impairments of dyslexia may arise from attentional deficits that have with substantial overlap with those of ADHD, and include deficits in attentional networks implicated in orienting attention to temporally presented stimuli.
22
Kan, Jing. "Spatial-temporal source reconstruction for magnetoencephalography." Thesis, University of York, 2011. http://etheses.whiterose.ac.uk/1636/.
Full textAbstract:
Magnetoencephalography (MEG) is a new non-invasive technique for the functional imaging of the human brain. It has been widely used in both research and clinical applications, for it has several superior properties, including a high-temporal resolution with no interference from the bone or the head-like fluid to the signal spatial transformation. In this thesis, we aim to develop a framework for MEG spatial-temporal current course reconstruction by introducing classical methods from the pattern recognition theory into medical imaging. These applications provide a new angle for research in MEG source reconstruction with the solution for source reconstruction at a single point, and improvements of the reconstruction on spatially and temporally. The whole thesis is based on three topics, which are designed to be parts of an integrated reconstruction process, and each of them are interrelated, rather than independent from each other. We firstly introduce the source reconstructionmethod at a single time point using the basis function extraction. In light of the assumption that the Laplacian eigenvectors of mesh can be the analogous to the basis functions that represent the cortex mesh; we build a new model to describe the current source that is distributed on each mesh vertex. This model consists of analogous basis functions and unknown weighted coefficients. In terms of experiment results, this algorithm shows good reconstructed property to the single stimulus, as well as the supercial stimulus on the cortical surface. Secondly, with respect to the spatial reconstructed sources by basis function method from the last topic, we build a new solution for improving the spatial-resolution of MEG source reconstruction at a single time point by introducing a classical method ( the Bayesian super-resolution method) from the pattern recognition theory. Although the approach is designed based on the reconstruction from basis functions, it is also feasible for other spatial reconstruction methods to improve the spatial-resolution. From the numerical experiment results, it is apparent that the spatial resolution has been effectively improved. Then, the MEG measurement system in the temporal field is assumed to be a linear dynamic system where the classical methods, Kalman filter and Kalman smoother, are applied as the solution for the estimation of source in time course. The Kalman filter is used to estimate the dynamic state while the Kalman smoother is applied for correcting the source distribution of the hidden state with the EMalgorithm. This approach shows superior performance to solve the inverse problem. It extends the improvement in source reconstruction using the temporal field. We construct the synthetic data as well as apply the realMEG data throughout all the experimental test of my work. In summary, this thesis builds three algorithms, which aim to reconstruct the MEG source distribution on spatial and temporal field respectively aided by methods from pattern recognition. This work provides a new angle of using the pattern recognition theory for MEG source reconstruction. Meanwhile, we also explore a new direction for applying the theory of pattern recognition. This work not only provides a good integration between these two fields, but also encourage future interactions.
23
Wang, Qian. "Characterizing InternetWorm Spatial-Temporal Infection Structures." FIU Digital Commons, 2010. http://digitalcommons.fiu.edu/etd/294.
Full textAbstract:
Since the Morris worm was released in 1988, Internet worms continue to be one of top security threats. For example, the Conficker worm infected 9 to 15 million machines in early 2009 and shut down the service of some critical government and medical networks. Moreover, it constructed a massive peer-to-peer (P2P) botnet. Botnets are zombie networks controlled by attackers setting out coordinated attacks. In recent years, botnets have become the number one threat to the Internet. The objective of this research is to characterize spatial-temporal infection structures of Internet worms, and apply the observations to study P2P-based botnets formed by worm infection. First, we infer temporal characteristics of the Internet worm infection structure, i.e., the host infection time and the worm infection sequence, and thus pinpoint patient zero or initially infected hosts. Specifically, we apply statistical estimation techniques on Darknet observations. We show analytically and empirically that our proposed estimators can significantly improve the inference accuracy. Second, we reveal two key spatial characteristics of the Internet worm infection structure, i.e., the number of children and the generation of the underlying tree topology formed by worm infection. Specifically, we apply probabilistic modeling methods and a sequential growth model. We show analytically and empirically that the number of children has asymptotically a geometric distribution with parameter 0.5, and the generation follows closely a Poisson distribution. Finally, we evaluate bot detection strategies and effects of user defenses in P2P-based botnets formed by worm infection. Specifically, we apply the observations of the number of children and demonstrate analytically and empirically that targeted detection that focuses on the nodes with the largest number of children is an efficient way to expose bots. However, we also point out that future botnets may self-stop scanning to weaken targeted detection, without greatly slowing down the speed of worm infection. We then extend the worm spatial infection structure and show empirically that user defenses, e.g., patching or cleaning, can significantly mitigate the robustness and the effectiveness of P2P-based botnets. To counterattack, we evaluate a simple measure by future botnets that enhances topology robustness through worm re-infection.
24
Musina, John. "Mechanisms of coexistence in nectar foraging bees : resource and temporal partitioning /." [Beersheba, Israel] : Ben-Gurion University of the Negev, 2009. http://aranne5.lib.ad.bgu.ac.il/others/MusinaJohn.pdf.
Full text
25
Naylor, Susan J. "Spatial context effects on temporal and spatial factors in map memory /." Thesis, Connect to Dissertations & Theses @ Tufts University, 1999.
Find full textAbstract:
Thesis (Ph.D.)--Tufts University, 1999.Adviser: Holly A. Taylor. Submitted to the Dept. of Psychology. Includes bibliographical references (leaves 59-61). Access restricted to members of the Tufts University community. Also available via the World Wide Web;
26
Farr, Daniel. "Resolving the Temporal-Spatial Ambiguity With the Auroral Spatial Structures Probe." DigitalCommons@USU, 2014. https://digitalcommons.usu.edu/etd/3728.
Full textAbstract:
The behavior of the electric and magnetic fields in the upper atmosphere of the Earth is scientifically interesting but difficult to study, since balloons and aircraft are unable to fly high enough to measure it directly. Sounding rockets, which make a one-time flight carrying instruments that measure the environment around them, have been successfully used to study the upper atmosphere. As the rocket flies through the upper atmosphere, it radios down data about the environment. When scientists on the ground use this data to construct a picture of the upper atmosphere, they run into a problem: the fields reported by the rocket change over time, but it is not clear whether this is because these fields are actually changing in time, or just because the rocket has moved to a different place where the fields are different. This inability to determine whether changes are happening in time or space is called the temporal-spatial ambiguity.
This thesis describes the Auroral Spatial Structures Probe (ASSP), a sounding rocket mission that attempts to resolve the temporal-spatial ambiguity by using multiple payloads flying in formation. Several payloads will pass through and measure the same point in space one after another, which will enable us to see how the fields are changing over time.
27
Gouraguine, Adam. "Habitat driven responses of reef fish : temporal change, niche partitioning and selection." Thesis, University of Essex, 2018. http://repository.essex.ac.uk/22278/.
Full textAbstract:
Shallow water tropical and temperate marine habitats are changing dramatically in response to many stressor-driven effects. The change in turn threatens the associated fish communities relying on their maintenance for habitat provision. At present, a much better understanding of the interaction between changing habitats and the associated fish is necessary. To address the lack of understanding of the habitat – fish association, mechanisms which underpin the habitat driven responses of reef fish were examined, from entire communities down to species level, across tropical and temperate ecosystems. Using a highly biodiverse ecosystem as the model system, effects of changing habitat on the associated fish community were observed, consequently demonstrating how important, in terms of shelter and food resources, the overall habitat is in structuring the fish community. Furthermore, patterns of habitat use of certain fish species within and across tropical and temperate ecosystems were examined. Variation in the size of the habitat used and its overlap between species within systems, and uniform patterns in habitat use and comparable fish habitat size and overlap across systems, were discovered. By looking at fish habitat use within systems, invaluable knowledge was gained on ecological interactions between habitat and fish on a small scale. At the same time, detection of similar mechanisms of fish habitat use across ecosystems indicates to possible uniform response of fish communities to habitat change at a large-scale. Finally, by looking at fish habitat selection using olfaction, in a temperate model system, a range of subtle behavioural responses displayed during habitat selection were detected. These results highlighted the extent of complexity of the mechanisms used in fish habitat selection and the ubiquitous importance of the habitat and its properties for the associated fish. In addition to, and based on the ecological significance of the findings, a number of potential management and conservational applications of the research were given within the thesis.
28
Girard, Léa. "Quorum Sensing in Vibrio spp. : AHL diversity, temporal dynamic and niche partitioning." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066650/document.
Full textAbstract:
Chez les Vibrio spp., le QS est impliqué dans de nombreuses fonctions comme la colonisation de niche écologiques, les stratégies de survie ou encore la virulence. Cependant, pour la majorité des espèces de Vibrio, la diversité des AHLs produites reste largement sous-estimée et l'étude du QS est encore limitée à quelques espèces modèles ou pathogènes. Toutefois, dans les environnements aquatiques, ces espèces sont minoritaires et les espèces les plus abondantes ne sont que très peu étudiées. Nos résultats ont révélé une importante diversité d'AHLs mais aussi, de façon surprenante, une hétérogénéité dans les phénotypes de production d'AHL au sein d'une même espèce de Vibrio. Pour la première fois, nous avons mis en évidence qu'une même souche de Vibrio pouvait présenter des phénotypes de production d'AHLs différent au cours du temps et une approche statistique a révélé l'implication de certains déterminants biotiques et abiotiques dans ces variations temporelles. Par ailleurs, une approche à micro-échelle a révélé une structuration des populations de Vibrio en unités fonctionnelles constituées de souches phylogénétiquement proches qui partagent des niches écologiques spécifiques et des comportements sociaux. Nos résultats ont mis en évidence que les modalités de communication pouvaient être hétérogènes suggérant l'absence d'un langage commun au sein de ces unités fonctionnelles. En conclusion, ce travail de thèse a permis d'apporter de nouvelles connaissances sur le QS chez les Vibrio dans l'environnement marin, de la souche à la population, et propose une vision intégrée des mécanismes de régulation de la production d'AHLs dans l'environnementQuorum sensing is an important mechanism among Vibrio species and is involved in many vital functions such as niche colonization, survival strategies or virulence. However, AHL diversity still largely underestimated for the majority of Vibrio species and the current knowledge on AHL-mediated QS is limited to a few pathogenic or bioluminescent species. Nonetheless, these species are weakly abundant in seawater while dominant species in the environment are poorly studied. Our results revealed a unexpected diversity of AHL molecules but also a quite surprising intra-species diversity of AHL production phenotypes. For the first time, we showed that different isolates of a single genotype switched between different AHL production phenotypes among time and we revealed the potential involvement of abiotic and biotic parameters in these variations. However, it appears that when studied at a microscale, Vibrio populations are showing a functional structuration in ecological units consisting of phylogenetically close strains sharing habitat and social traits. In this context, it was necessary to determine if these different AHL production phenotypes were associated to different micro-habitats in the water column. We did not demonstrate that a common language was spoken within ecological populations. This thesis work provide new insights on AHL-mediated QS among a broader range of species and among Vibrio populations and depicts the potential impact of multiple aspects of marine environments on AHL production
29
Greenlee, Jordan. "Temporal and spatial modeling of analog memristors." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41215.
Full textAbstract:
As silicon meets its performance limits, new materials and methods for advancing computing and electronics as a whole are being intensely researched, as described in Chapter 1. Memristors are a fusion of these two research areas, with new materials being pursued concurrently to development of novel architectures to take advantage of these new devices. A background of memristors and an overview of different memristive developments in the field are reviewed in Chapter 2.
Chapter 3 delves into the physical mechanisms of analog memristors. To investigate and understand the operation of analog memristors, a finite element method model has been developed.
More specifically, the devices simulated include a simple memristor simulation where the lithium ions (dopants) are confined to the device, but allowed to move in response to a voltage applied across the device. To model a more physical memristor, charge carrier mobility dependence on dopant levels was added to the device, resulting in a simulated device that operates similarly to the first simulation. Thereafter, the effect of varying geometries was modeled, and it was determined that both the speed and the resistance change of the device were improved by increasing the ratio of the top and bottom metal contact lengths in a restrictive flow geometry. Finally, the effect of dopant removal was investigated. It was determined that if the greatest change in resistance is required, then the removal of dopants is the optimal operating regime for an analog memristor.
Through a greater understanding of analog memristors developed by the simulation described herein, researchers will be able to better harness their power and implement them in bio-inspired systems and architectures.
30
Geberl, Cornelia. "Spatial and temporal resolution of bat sonar." Diss., Ludwig-Maximilians-Universität München, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:19-160582.
Full text
31
Xia, Jianhong, and not supplied. "Modelling the spatial-temporal movement of tourists." RMIT University. Mathematical and Geospatial Sciences, 2007. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080110.161021.
Full textAbstract:
Tourism is one of the most rapidly developing industries in the world. The study of spatio-temporal movement models of tourists are undertaken in variety of disciplines such as tourism, geography, mathematics, economics and artificial intelligence. Knowledge from these different fields has been difficult to integrate because tourist movement research has been conducted at different spatial and temporal scales. This thesis establishes a methodology for modelling the spatial-temporal movement of tourists and defines the spatial-temporal movement of tourists at both the macro and micro level. At the macro level, the sequence of tourist movements is modelled and the trend for tourist movements is predicted based on Markov Chain theory (MC). Log-linear models are then adopted to test the significance of the movement patterns of tourists. Tourism market segmentation based on the significant movement patterns of tourists is implemented using the EM (Expectation-Maximisation) algorithm. At the micro level, this thesis investigates the wayfinding decision-making processes of tourists. Four wayfinding models are developed and the relationships between the roles of landmarks and wayfinding decision-making are also discussed for each type of the wayfinding processes. The transition of a tourist movement between the macro and micro levels was examined based on the spatio-temporal zooming theory. A case study of Phillip Island, Victoria, Australia is undertaken to implement and evaluate the tourist movement models established in this thesis. Two surveys were conducted on Phillip Island to collect the macro and micro level movement data of tourists. As results show particular groups of tourists travelling with the same movement patterns have unique characteristics such as age and travel behaviours such as mode of transport. Effective tour packages can be designed based on significant movement patterns and the corresponding target markets. Tourists with various age groups, residency, gender and different levels of familiarity with physical environment have different wayfinding behaviours. The results of this study have been applied to tourism management on Phillip Island and the novel methods developed in this thesis have proved to be useful in improving park facilities and services provided to tourists, in designing tour packages for tourism market promotion and in understanding tourist wayfinding behaviours.
32
Osnas, Erik E. "Temporal and spatial structure of waterfowl communities." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ30815.pdf.
Full text
33
Chorley, N. "Spatial and temporal analysis of sunspot oscillations." Thesis, University of Warwick, 2011. http://wrap.warwick.ac.uk/47200/.
Full textAbstract:
Sunspots are the most conspicuous feature seen on the solar photosphere and are manifestations of the solar magnetic field. Their study, then, may provide us with a greater understanding of the dynamo mechanism thought to be responsible for the generation of this field. In this thesis, the oscillations of sunspots are studied by making use of observational data from two instruments: the Nobeyama Radioheliograph (NoRH) and the Solar Optical Telescope (SOT) on board the Hinode spacecraft. First, a study of long period oscillations was undertaken in which two long period peaks (P > 10 min) were identified in the power spectra of time series generated from sets of images of 3 sunspots observed with NoRH. In addition, by using the techniques of period, power, correlation and lag mapping, it was found that the power in each of these peaks was concentrated over the umbral regions and that there were two regions of approximately equal size oscillating in anti-phase with each other. It was suggested that these properties could be signatures of a "shallow" sunspot. A follow-up study was then performed, in which the lifetimes of the long period oscillations were investigated over a period of 9 days. These oscillations were seen to dominate the spectra during this interval and the periods and amplitudes were stable during that time. A simple model of a damped, driven simple harmonic oscillator (in which the driving term was nonlinear) was proposed to explain the generation and support of the oscillations. Finally, a study of the spatial properties of the 3 minute oscillations was performed by applying the mapping techniques mentioned above to Hinode/SOT data. The distributions of power and lag of maximum correlation coefficient were found to be non-uniform over the sunspots under study and this may be indicative of inhomogeneities of the physical quantities in the structures.
34
Richardson, Thomas Owen. "Spatial and temporal organisation within ant societies." Thesis, University of the West of England, Bristol, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.557142.
Full textAbstract:
In this thesis the organisation of colonies of the ant, Temnothorax albipennis, is investigated with a special focus on their spatial and temporal statistics. Individual-based modelling combined with analyses of experimental data are used extensively to infer the mechanisms that govern individual and collective behaviour. The unequal allocation of labour amongst different individuals, as manifested in skewed distributions of activity, is ubiquitous within the social insects. Early non-spatial individual-based models demonstrated that such skewed divisions of labour can self- organise through the interaction of fluctuating levels of stimuli associated with a task, with differentially sensitive agents that perform work upon the stimulus. Here, that modelling framework is extended by explicitly including space. This modification induces a 'percolation' effect, in which small differences amongst agents in their response thresholds, are related to large differences in their probabilities of performing work. The extension of the original fixed-threshold models of Division of Labour to include space means that they can be treated as a special case of diffusion in disordered media - a well studied branch of statistical mechanics. Staying at home to care for young or leaving to find food is one of the most fundamental divisions of labour. Here the rate of departures from ant nests and the collective activity of the individuals within the nest, are experimentally quantified. Both the rate of nest-leaving, and the inside-nest activity showed a non-linear decline over time. This and other results indicates that fluctuating record signals and repulsive ant-ant interactions play a significant role in colony organisation. A record signal is a new 'high water mark' in the history of a system. The dynamics of several complex but purely physical systems are also based on record signals but this is the first time they have been experimentally shown in a biological system. Finally, the generation of spatial pattern formation is experimentally investigated In the context of resilience to perturbations. The brood within the ant colony is often sorted into an intricate annular pattern, according to the developmental stage of the various rood types. Even after the pattern is completely destroyed, the workers are able to re-establish the pattern. The dynamics of this process of re-emergence is quantified in detail. Lastly, the possible utility of the pattern as a spatial cue to the workers is discussed.
35
Crema, E. R. "Spatial and temporal models of Jomon settlement." Thesis, University College London (University of London), 2013. http://discovery.ucl.ac.uk/1382589/.
Full textAbstract:
The Jomon culture is a tradition of complex hunter-gatherers which rose in the Japanese archipelago at the end of the Pleistocene (ca. 13,000 cal BP) and lasted until the 3rd millennium cal BP. Recent studies increasingly suggest how this long cultural persistence was characterised by repeated episodes of change in settlement pattern, primarily manifested as cyclical transitions between nucleated and dispersed distributions. Although it has been suggested that these events correlate with population dynamics, shifts in subsistence strategies, and environmental change, to date there have been very few attempts to provide a quantitative analysis of spatio-temporal change in Jomon settlement and its possible causes. This thesis is an attempt to fill that lacuna by adopting a twin-track approach to the problem. First, two case studies from central Japan have been examined using a novel set of methods, which have been specifically designed to handle the intrinsic chronological uncertainty which characterises most prehistoric data. This facilitated the application of a probabilistic framework for quantitatively assessing the available information, making it possible to identify alternating phases of nucleated and dispersed pattern during a chronological interval between 7000 and 3300 cal BP. Second, computer simulation (by means of an agent-based model) has been used to carry out a formal inquiry into the possible underlying processes that might have triggered the observed changes in the settlement pattern. The aim of this simulation exercise was two-fold. First, it has been used as a theory-building tool, combining several models from behavioural ecology and cultural transmission theory in order to provide explicit expectations in relation to the presence and absence of environmental disturbances. Second, the outcome of the simulation has been used as a template for linking the observed patterns to possible underlying socio-ecological processes suggested by the agent-based model. This endeavour has shown how some of the largest changes in the empirically observed settlement patterns can be simulated as emerging from the internal dynamics of the system rather than necessarily being induced by external changes in the environment.
36
White, Andrew. "Temporal and spatial dynamics of ecological systems." Thesis, University of Liverpool, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338459.
Full text
37
Alqarni, M. S. "Spatial temporal distribution of helical gyrotactic swimmers." Thesis, University of Liverpool, 2018. http://livrepository.liverpool.ac.uk/3024800/.
Full textAbstract:
We consider a spherical swimmer that undergoes helical motion due to the existence of a propulsive torque which is not parallel to a propulsive force that pulls the cell through the fluid. In addition, the cell is bottom-heavy; the centre of gravity is offset from the centre of buoyancy which generates a gravitational torque. In the presence of shear, fluid viscosity generates a further torque. Because cells swim at low Reynolds number, these torques are balanced. This thesis extends the model developed in Bearon (2013) in two distinct directions. Firstly, we consider an extension to the case of a flow where the shear varies with position. We consider a downward flow in a vertical channel. We observe that depending on the parameters, cells may exhibit the classical accumulation towards the centre of the channel or display a new focussing away from the centre. Secondly, we develop the model to describe randomness associated with changes in cell orientation. This is done by developing a Fokker-Planck equation for helical swimmers in terms of Euler angles. The classical Fokker-Planck equation obtained by Pedley and Kessler (1992) is a special case of the equation derived in this thesis. To implement this model numerically as an individual based model, we derive the corresponding stochastic differential equations. The Fokker-Planck equation and stochastic differential equation are extended to examine the spatial-temporal distribution of helical swimmers. We explore in detail how the horizontal distribution of cells in channel flow evolves to an equilibrium state, and how the evolution depends on the model parameters. For non-helical swimmers, we compare the result of the model to the recent experiments of Croze et al (2017).
38
Walford, Hannah Louise. "Spatial and temporal variation of African epeirogeny." Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620082.
Full text
39
Smith, Elizabeth M. "Spatial and temporal regulation of IL4Rα expression." Doctoral thesis, University of Cape Town, 2008. http://hdl.handle.net/11427/3117.
Full textAbstract:
Includes abstract.In this study, we generated a new mouse model, which allows both inducible and cell-specific deletion and reconstitution of IL-IL4Rα expression. This model has the potential to add a new dimension to our understanding of IL4Rα biology. This has been achieved by using the established Tet System (Goosen and Bujard, 1992) where the crossing of two complementary transgenic mouse lines enable the generation of the final double transgenic model. The first line expresses the transactivator, tTA, from the Tet-Off expression cassette driven by the Vav hemapoeitic specific promoter (Wiesner et al., 2005).
40
Fairbairn, Jonathan Paul. "Spatial and temporal dynamics of entomopathogenic nematodes." Thesis, University of Stirling, 2001. http://hdl.handle.net/1893/26685.
Full textAbstract:
The life-history and infection parameters of the entomopathogenic nematodes Steinernema feltiae (Filipjev)(Nematoda:Rhabditida) and Heterorhahditis megidis (Poinar, Jackson & Klein)(Nematoda:Rhabditida) were examined to provide specific details for the construction of mathematical SI models for biological control of soil insect pests. Laboratory experiments using the Greater Waxmoth, Galleria mellonella as the model host were undertaken to specifically examine the transmission behaviour of infective juvenile nematodes. The proportion of infective juveniles of S. feltiae which infected hosts was dependent on time. Previous studies declared that the proportion of infective juveniles which can infect is static, however, over a period of 5 days most of the infective juveniles infected hosts, demonstrating that the proportion infecting is dynamic. Infection of hosts by both species of nematode was compared using two mathematical representations of the transmission rate. Whereas the most parsimonious form of transmission for H. megidis was the linear Mass Action function, it was evident that, when measured at the individual nematode scale, S. feltiae transmission was non-linear. I postulated that this functional difference is due to the biology of the two species of nematodes. The subsequent effect of including the non-linear response on model predictions were investigated and it was demonstrated that the dynamics of the host nematode interaction became less stable. Spatial models of S. feltiae infection were parameterised from laboratory experiments, and control prediction of these models examined. The horizontal rate of dispersal through sand columns was determined in the presence and absence of hosts. Infective juveniles were found to disperse preferentially towards hosts. The predicted dynamics of pest control using the spatial moqel were highly dependent on the degree of nematode dispersal, host dispersal and the attraction of nematode infective juveniles towards hosts. The overall findings of this thesis have been placed in the context of epidemiological models created elsewhere, and predict that entomopathogenic nematodes may be targeted to specific pest systems with a high degree of success. An understanding of the infection biology of these nematode species is crucial in determining how and when pests may be controlled, and equally importantly, which systems successful control is not predicted.
41
Jiang, Bihan. "Spatial and temporal analysis of facial actions." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/25002.
Full textAbstract:
Facial expression recognition has been an active topic in computer vision since 90s due to its wide applications in human-computer interaction, entertainment, security, and health care. Previous works on automatic analysis of facial expressions have focused mostly on detecting prototypic expressions of basic emotions like happiness and anger. In contrast, the Facial Action Coding System (FACS) is one of the most comprehensive and objective ways to describe facial expressions. It associates facial expressions with the actions of the muscles that produce them by defining a set of atomic movements called Action Units (AUs). The system allows any facial expressions to be uniquely described by a combination of AUs. Over the past decades, extensive research has been conducted by psychologists and neuroscientists on various applications of facial expression analysis using FACS. Automating FACS coding would make this research faster and more widely applicable, opening up new avenues to understanding how we communicate through facial expressions. Morphology and dynamics are the two aspects of facial actions, that are crucial for the interpretation of human facial behaviour. The focus of this thesis is how to represent and learn the rich facial texture changes in both the spatial and temporal domain. The effectiveness of spatial and spatio-temporal facial representations and their roles in detecting the activation and temporal dynamics of facial actions are explored. In the spatial domain, a novel feature extraction strategy is proposed based on a heuristically defined regions from which a separate classifier is trained and fused in the decision-level. In the temporal domain, a novel dynamic appearance descriptor is presented by extending the static appearance descriptor Local Phase Quantisation (LPQ) to the temporal domain by using the Three Orthogonal Planes (TOP). The resulting dynamic appearance descriptor LPQ-TOP is applied to detect the latent temporal information representing facial appearance changes and explicitly model facial dynamics of AUs in terms of their temporal segments. Finally, a parametric temporal alignment method is proposed. Such strategy can accommodate very flexible time warp functions and is able to deal with both sequence-to-sequence and sub-sequence alignment. This method also opens up a new approach to the problem of AU temporal segment detection. This thesis contributes to facial action recognition by modelling the spatial and temporal texture changes for AU activation detection and AU temporal segmentation. We advance the performance of state-of-the-art facial action recognition systems and this has been demonstrated on a number of commonly used databases.
42
Monteiro, Fernando C. "Region-based spatial and temporal image segmentation." Doctoral thesis, Universidade do Porto, Faculdade de Engenharia, 2008. http://hdl.handle.net/10198/1835.
Full textAbstract:
This work discusses region-based representations for image and video sequence segmentation. It presents effective image segmentation techniques and demonstrates how these techniques may be integrated into algorithms that solve some of the motion segmentation problems. The region-based representation offers a way to perform a first level of abstraction and to reduce the number of elements to process with respect to the classical pixel-based representation.
Motion segmentation is a fundamental technique for the analysis and the understanding of image sequences of real scenes. Motion segmentation 'describes' the sequence as sets of pixels moving coherently across one sequence with associated motions. This description is essential to the identification of the objects in the scene and to a more efficient manipulation of video sequences.
This thesis presents a hybrid framework based on the combination of spatial and motion information for the segmentation of moving objects in image sequences accordingly with their motion. We formulate the problem as graph labelling over a region moving graph where nodes correspond coherently to moving atomic regions. This is a flexible high-level representation which individualizes moving independent objects. Starting from an over-segmentation of the image, the objects are formed by merging neighbouring regions together based on their mutual spatial and temporal similarity, taking spatial and motion information into account with the emphasis being on the second. Final segmentation is obtained by a spectral-based graph cuts approach.
The initial phase for the moving object segmentation aims to reduce image noise without destroying the topological structure of the objects by anisotropic bilateral filtering. An initial spatial partition into a set of homogeneous regions is obtained by the watershed transform. Motion vector of each region is estimated by a variational approach. Next a region moving graph is constructed by a combination of normalized similarity between regions where mean intensity of the regions, gradient magnitude between regions, and motion information of the regions are considered. The motion similarity measure among regions is based on human perceptual characteristics. Finally, a spectral-based graph cut approach clusters and labels each moving region.
The motion segmentation approach is based on a static image segmentation method proposed by the author of this dissertation. The main idea is to use atomic regions to guide a segmentation using the intensity and the gradient information through a similarity graph-based approach. This method produces simpler segmentations, less over-segmented and compares favourably with the state-of-the-art methods. To evaluate the segmentation results a new evaluation metric is proposed, which takes into attention the way humans perceive visual information.
By incorporating spatial and motion information simultaneously in a region-based framework, we can visually obtain meaningful segmentation results. Experimental results of the proposed technique performance are given for different image sequences with or without camera motion and for still images. In the last case a comparison with the state-of-the-art approaches is made.
43
Ewing, Tony. "Time Based Requirements and Partitioning of Systems with Automatic Test Case Generation." Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/195744.
Full textAbstract:
Automatic test case generation is a process that starts with text based functional requirements which are converted to a formal system requirements model. Once the formal system requirements model is created the automatic test case generation software creates a set of test scenarios that will verify that the requirements are all met. The automatic test case generation software accomplishes the conversion in a four step process: create base scenarios, identify unverified requirements, enhance scenarios to cover all requirements and allow black box testing, and then combine the scenarios into a single scenario tree. The automatic test case generation system outputs a set of scenarios by walking the final scenario tree. This dissertation expands on automatic test case generation for embedded systems in two major ways. The first is to extend functional automatic test case generation to allow for time based requirements as first class objects. The second is to use the automatic test case generation system to enable system partitioning decisions. The addition of time based requirements to the automatic test case generation system allows more complex systems to be developed. By providing a partitioning recommendation based on the test cases generated from the system requirements, the scope and capabilities of a single designer can be expanded to more complex systems. The resulting upgrades to the theory of automatic test case generation could be applied to the existing tools or incorporated in modern UML/SysML based design tools.
44
Loach, Daniel. "Inhibitory processes in temporal selection." Thesis, Bangor University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275136.
Full text
45
Ralley, Richard. "Spatial constraints on attention." Thesis, University of Hertfordshire, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302301.
Full text
46
Corral, Gavin Richard. "Quantifying and Mapping Spatial Variability in Simulated Forest Plots." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/77887.
Full textAbstract:
Spatial analysis is of primary importance in forestry. Many factors that affect tree development have spatial components and can be sampled across geographic space. Some examples of spatially structured factors that affect tree growth include soil composition, water availability, and growing space. Our goals for this dissertation were to test the efficacy of spatial analysis tools in a forestry setting and make recommendations for their use. Reliable spatial analysis tools will lead to more effective statistical testing and can lead to useful mapping of spatial patterns.
The data for this project is from simulated even aged loblolly pine stands (Pinus taeda L.). These simulated stands are grown at regular spacing and we impose a range of parameters on the stands to simulate many possible scenarios. In chapter 3 of this dissertation we perform a sensitivity analysis to determine if our methods are suitable for further research and applications. In chapter 4 we perform our analysis on more realistic data generated by a spatially-explicit stand simulator, PTAEDA 4.1.
In chapter 3 we performed a statistical simulation of plantation stands without effects of competition and mortality. We used redundancy analysis (RDA) to quantify spatial variability, partial redundancy analysis (pRDA) to test for spatial dependence, and spatially constrained cluster analysis to map soil productivity. Our results indicated that RDA and pRDA are reliable methods and future evaluation is appropriate. The results from the spatially constrained cluster analysis were less clear. The success or failure of the clustering algorithm could not be disentangled from the success or failure of the selection criterion used to predict the number of clusters. Further investigations should address this concern.
In chapter 4 we used PTAEDA 4.1, a loblolly stand simulator, to simulate a range of site conditions and produce data that we could use for analysis. The results showed that RDA and pRDA were not reliable methods and ready for the field. Spatially constrained cluster analysis performed poorly when more realistic data was used and because of this further use was uncertain. It was clear from the results that levels of variation and spatial pattern complexity of microsites influenced the success rate of the methods. Both RDA and pRDA were less successful with higher levels of variation in the data and with increased spatial pattern complexity.
In chapter 5 we related the coefficient of variation from our simulations in (chapters 3 and 4) to two sets of real plot data, including a clonal set and open pollinated set. We then implemented a spatial analysis of the real plot data. Our spatial analysis results of the two comparable data sets were unaffected by genetic variability indicating that the primary source of variability across plots appears to be soil and other factors, not genetic related.Ph. D.
47
Ji, Wei. "Spatial Partitioning and Functional Shape Matched Deformation Algorithm for Interactive Haptic Modeling." Ohio University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1226364059.
Full text
48
Bränd, Stefan. "Using Rigid Landmarks to Infer Inter-Temporal Spatial Relations in Spatio-Temporal Reasoning." Thesis, Linköpings universitet, Artificiell intelligens och integrerad datorsystem, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-124064.
Full textAbstract:
Spatio-temporal reasoning is the area of automated reasoning about space and time and is important in the field of robotics. It is desirable for an autonomous robot to have the ability to reason about both time and space. ST0 is a logic that allows for such reasoning by, among other things, defining a formalism used to describe the relationship between spatial regions and a calculus that allows for deducing further information regarding such spatial relations. An extension of ST0 is ST1 that can be used to describe the relationship between spatial entities across time-points (inter-temporal relations) while ST0 is constrained to doing so within a single time-point. This allows for a better ability of expressing how spatial entities change over time. A major obstacle in using ST1 in practise however, is the fact that any observations made regarding spatial relations between regions is constrained to the time-point in which the observation was made, so we are unable to observe inter-temporal relations. Further complicating things is the fact that deducing such inter-temporal relations is not possible without a frame of reference. This thesis examines one method of overcoming these problems by considering the concept of rigid regions which are assumed to always be unchanging and using them as the frame of reference, or as landmarks. The effectiveness of this method is studied by conducting experiments where a comparison is made between various landmark ratios with respect to the total number of regions under consideration. Results show that when a high degree of intra-temporal relations are fully or partially known, increasing the number of landmark regions will reduce the percentage of inter-temporal relations to be completely unknown. Despite this, very few inter-temporal relations can be fully determined even with a high ratio of landmark regions.
49
Owens, Eli Thomas. "Investigating Granular Structure with Spatial and Temporal Methods." Thesis, North Carolina State University, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=3538538.
Full textAbstract:
This dissertation reports studies of the internal structure of jammed granular materials and how granular sound propagation and vibrational modes are influenced by disorder in particle positions and contact forces. We investigate the role of particle scale forces on sound amplitude and speed, how to characterize the bulk pressure via the density of states, and force network modularity. We perform our experiments on a vertical, 2D, photoelastic granular material. Acoustic waves are excited from the bottom of the system and observed via particle scale sensors and a high speed camera. This novel combination of spatial and temporal measurements allows us to observe the role of force chains in sound propagation. The sound amplitude is largest through particles with strong contact forces, and we see that sound travels fastest along high force paths, giving rise to multiple sound speeds. Combining acoustic excitations with a method from thermal physics, we developed a new method to measure the density of modes, D(f). From D( f), we define a critical frequency, fc, that scales with the bulk pressure, and comparing D( f) to Debye scaling, we find an excess of low frequency modes. Disorder in the force chain network and particle configurations plays a crucial role in D(f), as Debye scaling is only recovered for high pressure, hexagonally ordered packings. Finally, we characterize the force network by dividing it into modules of highly connected nodes. These communities become progressively more ordered as the pressure on the system is increased and the force chains become more uniform. Together, these studies illustrate the importance of the force chains in understanding static and dynamic granular properties.
50
Pan, Feifei. "Spatial and temporal structures of soil moisture fields." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/32842.
Full text