Dissertationen: „Timber decay“

1

Le, Poidevin Janine. „Timber permeability : significance for joinery decay“. Thesis, Imperial College London, 1986. http://hdl.handle.net/10044/1/38083.

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2

Lee, Hyun-Mi. „Aspects of wood decay and preservation of timber“. Thesis, Liverpool John Moores University, 2009. http://researchonline.ljmu.ac.uk/5941/.

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A number of species of wood decay fungi important for the damage they cause to timber and timber products in Korea were cultured. Trametes versicolor, which is one of the most important, was also cultured from a collection made in the UK and likewise the ascomycete Daldinia concentica was obtained for comparative studies. In the initial testing of the effectiveness of the two wood preservatives, ammoniacal copper quaternary (ACQ) and copper azole (CuAz) preserve injected blocks of Japanese Red Pine and Yellow Poplar were inoculated with T versicolor, Pleurotus ostreatus and D. concentrica. Weight loss(%) of the wood blocks showed that Japanese Red Pine possessed greater natural resistance to decay by the white rot basidiomycete fungus T versicolor, than to the white rot ascomycete D. concentrica. The results for Yellow Poplar were the opposite. It was also found that both preservatives had an inhibitory effect on all three test fungi regardless of tree species. Furthermore ACQ was the most effective preservative in relation to T versicolor, which is the most damaging wood decay fungus in Korea. It has also been found that the absorption of the preservatives by the two different wood types differed with Yellow Poplar exhibiting a slightly greater absorption than the Japanese Red Pine, which might be a result of differences in the anatomical structure of the woods. Fungal biomass was also determined using chitin and ergosterol assays. The results regarding levels of decay caused by T versicolor, P ostreatus and D. concentrica are in close agreement with the weight loss determinations. The assays also confirmed the effectiveness of the copper based preservatives. The application of Scanning Electron Microscopy (SEM) has allowed observations on the damage caused by the test fungi to the untreated blocks of the two wood species and the reduction in damage on blocks treated with the preservatives. Linked studies using the SEM and Atomic Force Microscopy have demonstrated differences in the micromorphology of the hyphal tips of the test fungi.

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3

McGeachie, M. T., University of Western Sydney, College of Law and Business und of Construction Property and Planning School. „Characterisation of the Sydney region in relation to corrosion, timber decay risk factors and the corrosion of nails in timber in covered conditions“. THESIS_CLAB_CPP_McGeachie_M.xml, 2001. http://handle.uws.edu.au:8081/1959.7/491.

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The aim of the study was to characterise the environment in the Sydney region in respect of atmospheric corrosivity, timber decay risk factors and the corrosion of nails in timber in covered conditions. The study reviewed contemporary research in this field, particularly in Australia, developing an understanding of the durability failure mechanisms for timber and nails in timber. The study looked at the effects of climatic aspects, pollutants, corrosion on timber decay risk factors. The study found that the levels of risk in terms of timber degradation, corrosion and nail corrosion were greatest adjacent to the coast and at marine sites.
Doctor of Philosophy (PhD)

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4

Vigrow, Anne. „Molecular analysis of the dry rot fungus Serpula lacrymans“. Thesis, University of Abertay Dundee, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306791.

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5

McGeachie, Mark Thomas. „Characterisation of the Sydney region in relation to corrosion, timber decay risk factors and the corrosion of nails in timber in covered conditions /“. View thesis View thesis, 2001. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20030326.082457/index.html.

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6

Score, Alan James. „Biological control of the dry rot fungus Serpula lacrymans“. Thesis, University of Abertay Dundee, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264798.

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7

Moreira-Munoz, Simon. „Timber supply and economic impact of mountain pine beetle salvage strategies“. Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/697.

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To address the scale mountain pine beetle (MPB) outbreak in British Columbia, salvage has become fully integrated with timber supply strategies. The objective of this thesis is to assess the economic impact of different salvage strategies depending on different attack levels, decay rates, and stakeholder discount rates. The study area is located in N.E. British Columbia where the MPB has not yet reached its peak and where susceptible to attack stands account for 40% of the area. Salvage strategies were modelled with a timber supply model (Woodstock) which uses a linear programming type II optimization approach. Performance of the model was assessed over a range of indicators such as NPV, profit, salvage proportion, species composition, inventory levels, and non-recoverable volume. Sensitivity analyses were conducted on harvest flow, discount rate, and ending inventory. The model was very sensitive to the intensity of attack and less sensitive to the decay level. The high level of attack resulted in large volume losses, mostly as un-salvaged inventory. Although allowable annual cut (AAC) uplifts have an economic benefit, they do not necessarily maximize the salvage of pine. Non-pine species are an important component of the salvage and these species are also essential for the future timber supply. If the objective is to ensure quality and quantity of the future forest, policies have to complement AAC uplifts by strongly encouraging the salvage of mainly pine-leading stands and management options that minimize the “by-catch” of non-pine species and minimize destruction of advanced regeneration during salvage. However, this has an opportunity cost for the private industry where the objective is to maximize profit. If the salvage strategy focuses on decreasing the impact on cash flows, achieving desirable ending inventory levels, avoiding salvage of stands after shelf-life, and reducing impact on non-attack species, then the current harvest level will likely lead to a mid-term timber supply fall-down. Using the fibre for bioenergy production is an alternative if managing for bioenergy can be integrated into harvest operations. However, unlike mill residues, the bioenergy supply has to fully account for harvest and transportation costs of dead wood to the mill.

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8

Kumi-Woode, Benjamin G. „Natural decay resistance of some Ghanian timbers and wood decay hazard potential for Ghana“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1996. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/MQ33402.pdf.

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9

Brown, Heather. „Biological control of wood decay in ground contact timbers“. Thesis, Abertay University, 2002. https://rke.abertay.ac.uk/en/studentTheses/404b141f-ed6c-4363-a96a-27ba3ab1f68a.

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Wood placed in ground contact situations is susceptible to attack by a wide range of soil micro-organisms which degrade the wood structure, causing significant deterioration of the mechanical properties of the timber such as strength and elasticity. Chemical preservatives such as CCA (copper-chrome-arsenic) and CCB (copper-chrome-boron) are currently used to prevent the decay of wood exposed to biodeteriogens. However, increasing concerns regarding the long-term environmental effects of the toxic chemicals applied to ground contact timbers has resulted in the investigation and development of a number of alternatives to chemical preservation. This project examined the use of biological control as a means of protecting ground contact timbers from fungal decay. Trichoderma spp. are soil-inhabiting fungi with broad-spectrum antagonistic properties, and have been extensively investigated as potential biocontrol agents in agriculture and forestry. A small-scale wood-based screening system was developed for the rapid assessment of biocontrol potential. The screening system used non-sterile soil as a test medium to provide a natural environment for the evaluation of potential biocontrolagents. A number of Trichoderma isolates were tested using the developed system, andone Trichoderma viride isolate, (T60) demonstrated an initial protective effect against non-sterile soil. This isolate has previously been shown to be totally effective against basidiomycete decay fungi. The isolate was therefore selected as a potential biocontrol agent for ground contact timber, and a field trial was designed to assess the isolate on a larger scale. Development of the field trial included the formulation of an appropriate delivery system. The biocontrol agent was applied to wood as a fungal spore suspension prepared in water. Wood was pressure impregnated with spores using a pilot preservation plant, integrating biological control strategies with current industry processes. Spore viability was retained, as indicated by the germination of Trichoderma spores on the wood surface. Field trial and fungal cellar testing of the biocontrol agent on ground contact was based on European Standard test methods for chemical wood preservatives. T60-treated stakes, CCA-treated stakes and untreated control stakes of 2 softwood species were uplifted after 9 and 18 months exposure to soil. Recommended subjective assessmentswere supplemented with biological examinations of decay. Results indicated partial protection of T60-treated wood. However, the study highlighted the influence of test system and wood species on the activity and behaviour of the applied biocontrol agent. To assess the distribution of the biocontrol agent in wood following the novel application procedure, a molecular-based method for the specific detection and quantification of T60 in treated wood was investigated. DNA was extracted from wood and amplified using the polymerase chain reaction (PCR). A random primer was used to detect T60 DNA in extracted material, and image analysis software was utilised to assess the relative abundance of amplified DNA indicating a non-uniform distribution of detected spores. In summary, results from the field and fungal cellar testing of a selected biocontrol isolate showed a variation in the degree and constancy of protection against wood decay fungi. Standard testing guidelines were used as a basis for a field trial, with modifications designed to provide a more comprehensive assessment of biological control in ground contact timbers. The research presented in this thesis highlights the importance of field testing with regard to the biological control of wood decay, and indicates the influence of environmental factors on the overall performance of fungal biocontrol agents.

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10

Mouzouras, R. „Microbiological aspects of stored timbers from the Mary Rose and the decay of wood by marine fungi“. Thesis, University of Portsmouth, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376466.

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11

Danko, V. A., P. E. Shepeliavyi, K. V. Michailovska und I. Z. Indutnyi. „Absorption Cross Section and Photoluminescence Lifetime of Silicon-Based Light-Emitting nc-Si-SiOx Structures“. Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35011.

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The spectral dependence of the photoluminescence (PL) decay kinetics at room temperature have been studied in porous nc-Si-SiOx nanostructures. Investigated samples were obtained by oblique evaporation of SiO with following annealing at 975 C in vacuum and treating in the HF vapor at 50 C. PL decay in these structures described by a stretched exponential and the average lifetime of the PL decrease exponentially with increasing energy of photons. PL lifetime values is in microsecond range that point out on phonon participation in radiative recombination. Dispersion parameter do not depend on emission energy and tends to 1 with increasing porosity, which is consistent with the model of noninteracting nc-Si. It was established, that the absorption cross section σ of the nc-Si particles increase with decreasing of nc-Si dimensions and increasing of emission energy. This result is consistent with the quantum confinement effects, where the smaller nc-Si with larger energy gaps are characterized by a short radiative lifetime and the corresponding radiative recombination process take place within the individual nc-Si. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35011

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12

Reed, Alan Thomas. „Decay studies of neutron-rich nuclei“. Thesis, University of Liverpool, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367175.

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13

Ferguson, Colin. „Mass modelling in X-/#gamma#-ray astronomy“. Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327364.

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14

Zhang, Nien-fan. „Estimating partial group delay“. Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/74721.

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Partial group delay is a spectral parameter, which measures the time lag between two time series in a system after the spurious effects of the other series in the system have been eliminated. For weakly-stationary processes, estimators for partial group delay are proposed based on indirect and direct approaches. Conditions for weak consistency and asymptotic normality of the proposed estimators are obtained. Applications to a multiple test of partial group delay are investigated. The time lag interpretation of partial group delay is justified, which provides insight into the nature of linear relationships among weakly-stationary processes. Extensions are made to group delay estimation and partial group delay estimation for non-stationary "oscillatory" processes.
Ph. D.

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15

Swaminathan, Prasanna V. „Measurement of Charge Storage Decay Time and Resistivity of Spacecraft Insulators“. DigitalCommons@USU, 2004. https://digitalcommons.usu.edu/etd/2094.

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Insulators used in the construction of spacecraft are irradiated with high-energy electrons in the space environment and this sometimes causes the insulators to charge to very high voltages. Such charged insulators can generate spontaneous electric partial-discharge pulses of the order of mA to tens of A. These pulses sometimes last enough time to destroy the expensive micro-circuitry present in the spacecraft. In evaluating the threat to the spacecraft due to these discharges, calculation of the resistivity becomes a critical parameter since it determines how accumulated charge will distribute across the spacecraft and how rapidly charge imbalance will dissipate. So far, resistivity values for the insulators for spacecraft applications have been simply imported from tabulated results measured using standard American Society for Testing and Materials (ASTM) and International Electro-technical Commission (IEC) methods. This thesis work provides the details of the charge storage method which has been found to be more appropriate in calculating the resistivity of spacecraft insulators by emulating the space environment better. This method is based on the concept that the resistivity is better measured as the decay of the charge deposited on the surface of an insulator, rather than by the flow of current across two electrodes around the sample which is the case with the classical method of measurements. From the results obtained from the charge storage method, it has been found that the ASTM resistivity values for thin film insulating spacecraft materials have been found to under-predict charge transport values applicable to many spacecraft charging problems, by 10 to 104 times. The charge storage method has only one side of the insulator in vacuum exposed to charged particles, light and plasma, with a metal electrode attached to the other side of the insulator. The chamber for measuring the charge storage decay has been designed with the capability to measure 32 samples simultaneously. The details of the apparatus, instrumentation, test methods, data acquisition methods, and data analysis for measuring resistivity of the spacecraft insulators are given here. Details about the vacuum environment, sample mounting, isolation of the samples, charging of the samples, measurement of the surface charge, rotary motion of the sample carousel, etc., are also given. The report also includes differences between the classical methods and the charge storage method both in terms instrumentation and methodology. The results obtained from both methods are tabulated showing the superiority of the charge storage method. Recommendations for future work are also included.

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16

Bai, Yuqiong. „ANALYSIS OF AIRCRAFT ARRIVAL DELAY AND AIRPORT ON-TIME PERFORMANCE“. Master's thesis, University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2573.

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In this research, statistical models of airport delay and single flight arrival delay were developed. The models use the Airline On-Time Performance Data from the Federal Aviation Administration (FAA) and the Surface Airways Weather Data from the National Climatic Data Center (NCDC). Multivariate regression, ANOVA, neural networks and logistic regression were used to detect the pattern of airport delay, aircraft arrival delay and schedule performance. These models are then integrated in the form of a system for aircraft delay analysis and airport delay assessment. The assessment of an airport¡¯s schedule performance is discussed. The results of the research show that the daily average arrival delay at Orlando International Airport (MCO) is highly related to the departure delay at other airports. The daily average arrival delay can also be used to evaluate the delay performance at MCO. The daily average arrival delay at MCO is found to show seasonal and weekly patterns, which is related to the schedule performance. The precipitation and wind speed are also found contributors to the arrival delay. The capacity of the airport is not found to be significant. This may indicate that the capacity constraint is not an important problem at MCO. This research also investigated the delays at the flight level, including the flights with delay ¡Ý0 minute and the flights with delay ¡Ý15min, which provide the delay pattern of single arrival flights. The characteristics of single flight and their effect on flight delay are considered. The precipitation, flight distance, season, weekday, arrival time and the time spacing between two successive arriving flights are found to contribute to the arrival delay. We measure the time interval of two consecutive flights spacing and analyze its effect on the flight delay and find that for a positively delayed flight, as the time space increases, the probability of the flights being delayed will decrease. While it was possible to calculate the immediate impact of originating delays, it is not possible to calculate their impact on the cumulative delay. If a late departing aircraft has no empty space in its down line schedule, it will continue to be late. If that aircraft enters a connecting airport, it can pass its lateness on to another aircraft. In the research we also consider purifying only the arrival delay at MCO, excluding the flights with originating delay >0. The model makes it possible to identify the pattern of the aircraft arrival delay. The weather conditions are found to be the most significant factors that influence the arrival delay due to the destination airport.
M.S.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Civil Engineering

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17

Mumm, Hans Pieter. „A test of time reversal violation in neutron beta decay /“. Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/9802.

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18

Pietarila, Kristel M. Fales Roger. „Developing and automating time delay system stability analysis of dynamic systems using the Matrix Lambert W (MLW) function method“. Diss., Columbia, Mo. : University of Missouri--Columbia, 2009. http://hdl.handle.net/10355/6180.

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Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 16, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dissertation advisor: Dr. Roger Fales. Vita. Includes bibliographical references.

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19

Du, Baozhu, und 杜宝珠. „Stability analysis and controller synthesis of continous-time linear time-delay systems“. Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B44765186.

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20

Corvi, Andrea P. „Subjective Time Perception Predicts Delay of Gratification“. Case Western Reserve University School of Graduate Studies / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1291765358.

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21

Zinck, Melissa M. „A COMPARISON STUDY OF CONSTANT TIME DELAY AND PROGRESSIVE TIME DELAY IN THE ACQUISITION OF ACADEMIC CONTENT FOR STUDENTS WITH INTELLECTUAL DISABILITIES“. UKnowledge, 2018. https://uknowledge.uky.edu/edsrc_etds/59.

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Constant time delay (CTD) and progressive time delay (PTD) are both evidence-based practices used to teach students with intellectual disability (ID). The prompt delay strategies have been used for instruction with academics, social, vocational, and communication skills. There is limited research regarding the differential effectiveness of the time delay variations for teaching academic content to students with ID. The present study compares the effects of CTD and PTD in the acquisition of academic content with four students with ID. An adapted alternating treatments design was used to compare the effectiveness and efficiency of the two procedures. Generalization was assessed across settings, participants, and materials. Results indicated that both strategies were effective but PTD was more efficient in regards to number of errors and average time to criterion.

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22

嚴利興 und Li-hing Yim. „Some stability results for time-delay control problems“. Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B31225482.

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23

Yim, Li-hing. „Some stability results for time-delay control problems“. Hong Kong : University of Hong Kong, 2000. http://sunzi.lib.hku.hk/hkuto/record.jsp?B22926094.

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24

Bevan, Matthew Gareth. „Investigating differences in the decay of divorce-induced residential mobility across gender and urbanisation“. Thesis, Malmö universitet, Fakulteten för kultur och samhälle (KS), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-21258.

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Divorce is a life course event that triggers deviant, negative residential moves that symbolises the antithesis of climbing the traditional housing ladder, and sets individuals on an altered housing trajectory, typically associated with long-term instability compared to married counterparts. Studies have revealed that long-term instability associated with divorce is commonly connected to an increased probability of moving out of owner occupation that is greater and persists longer for women than men. Similarly, studies examining the immediate effects of divorce typically identify that women have a higher risk of moving out of the matrimonial home at the time of separation. No studies found have examined the time taken for divorcing individuals to assume their new altered housing trajectories. This study aims to develop an understanding in this regard by examining gendered differences in the time taken for individual mobility rates to assume their new housing trajectory, and considering what effects urbanisation has on divorce-induced mobility. Using the Swedish LISA database, groups of divorcing single parents with cohabiting children under 18 are compared to similar long-term divorcees whom are conceptualised to represent the post-divorce altered housing trajectory. Noteworthy findings include: 1) Divorce-induced mobility at the time of separation decays one year after divorce for Rural and Urban male groups, at which time the new housing trajectory was assumed. 2) The decay time for Big City males was four years. 3) The decay time for Urban females was four years, while Rural and Big City female groups remained at an elevated mobility state for all four years observed post-divorce. 4) Degree of Urbanisation has a significant impact for women, mobility was highest in Rural groups and lowest in Big City groups. However, no such effect is observed for males. This study is important to municipalities and urban planners because the findings presented here concerning gendered and regional impacts on mobility are relevant to forecasting housing demand. Moreover, national planners are concerned with regional inequalities and the finding that degrees of urbanisation has a mobility association for females, but not males, is interesting in light of Sweden’s rural development and gender equality goals.

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25

Mitchell, Richard James. „Multi-microprocessor control of processes with pure time delay“. Thesis, University of Reading, 1987. http://centaur.reading.ac.uk/18826/.

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26

Eriksson, Daniel. „How to implement Bounded-Delay replication in DeeDS“. Thesis, University of Skövde, Department of Computer Science, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-646.

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In a distributed database system, pessimistic concurrency control is often used to ensure consistency which implies that the execution time of a transaction is not predictable. The execution time of a transaction is not dependent on the local transactions only, but on every transaction in the system.

In real-time database systems it is important that transactions are predictable. One way to make transactions predictable is to use eventual consistency where transactions commit locally before they are propagated to other nodes in the system. It is then possible to get predictable transactions due to the fact that the execution time of the transaction only depends on concurrent transactions on the local node and not on delays on other nodes and delays from a network.

In this report an investigation is made on how a replication protocol using eventual consistency can be designed for, and implemented in, DeeDS, a distributed real-time database prototype. The protocol consists of three parts: a propagation method, a conflict detection algorithm, and a conflict resolution mechanism. The conflict detection algorithm is based on version vectors. The focus is on the propagation mechanism and the conflict detection algorithm of the replication protocol.

An implementation design of the replication protocol is made. A discussion on how the version vectors may be applied in terms of granularity (container, page, object or attribute) and how the log filter should be designed and implemented to suit the particular conflict detection algorithm is carried out. A number of test cases with focus on regression testing have been defined.

It is concluded that the feasibility of the conflict detection algorithm is dependent on the application type that uses DeeDS.

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Sidhu, Bobjot Singh. „Exploring Data Driven Models of Transit Travel Time and Delay“. DigitalCommons@CalPoly, 2016. https://digitalcommons.calpoly.edu/theses/1601.

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Transit travel time and operating speed influence service attractiveness, operating cost, system efficiency and sustainability. The Tri-County Metropolitan Transportation District of Oregon (TriMet) provides public transportation service in the tri-county Portland metropolitan area. TriMet was one of the first transit agencies to implement a Bus Dispatch System (BDS) as a part of its overall service control and management system. TriMet has had the foresight to fully archive the BDS automatic vehicle location and automatic passenger count data for all bus trips at the stop level since 1997. More recently, the BDS system was upgraded to provide stop-level data plus 5-second resolution bus positions between stops. Rather than relying on prediction tools to determine bus trajectories (including stops and delays) between stops, the higher resolution data presents actual bus positions along each trip. Bus travel speeds and intersection signal/queuing delays may be determined using this newer information. This thesis examines the potential applications of higher resolution transit operations data for a bus route in Portland, Oregon, TriMet Route 14. BDS and 5-second resolution data from all trips during the month of October 2014 are used to determine the impacts and evaluate candidate trip time models. Comparisons are drawn between models and some conclusions are drawn regarding the utility of the higher resolution transit data. In previous research inter-stop models were developed based on the use of average or maximum speed between stops. We know that this does not represent realistic conditions of stopping at a signal/crosswalk or traffic congestion along the link. A new inter-stop trip time model is developed using the 5-second resolution data to determine the number of signals encountered by the bus along the route. The variability in inter-stop time is likely due to the effect of the delay superimposed by signals encountered. This newly developed model resulted in statistically significant results. This type of information is important to transit agencies looking to improve bus running times and reliability. These results, the benefits of archiving higher resolution data to understand bus movement between stops, and future research opportunities are also discussed.

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Lorenz, Robert. „Weak approxamation of stochastic delay“. Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät II, 2006. http://dx.doi.org/10.18452/15488.

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Wir betrachten die stochastische Differentialgleichung mit Gedächtnis (SDDE) mit Gedächtnislänge r dX(t) = b(X(u);u in [t-r,t])dt + sigma(X(u);u in [t-r,t])dB(t) mit eindeutiger schwacher Lösung. Dabei ist B eine Brownsche Bewegung, b and sigma sind stetige, lokal beschränkte Funktionen mit Definitionsbereich C[-r,0], und X(u);u in [t-r,t] bezeichnet das Segment der Werte von X(u) für Zeitpunkte u im Intervall [t,t-r]. Unser Ziel ist eine Folge von diskreten Zeitreihen Xh höherer Ordung zu konstruieren, so dass mit h gegen 0 die Zeitreihen Xh schwach gegen die Lösung X der stochastischen Differentialgleichung mit Gedächtnis konvergieren. Desweiteren werden wir Bedingungen angeben, unter denen eine gegeben Folge von Zeitreihen Xh höherer Ordung schwach gegen die Lösung X einer stochastischen Differentialgleichung mit Gedächtnis konvergiert. Als ein Beispiel werden wir den schwachen Grenzwert einer Folge von diskreten GARCH-Prozessen höherer Ordnung ermitteln. Dieser Grenzwert wird sich als schwache Lösung einer stochastischen Differentialgleichung mit Gedächtnis herausstellen.
Consider the stochastic delay differential equation (SDDE) with length of memory r dX(t) = b(X(u);u in [t-r,t])dt + sigma(X(u);u in [t-r,t])dB(t), which has a unique weak solution. Here B is a Brownian motion, b and sigma are continuous, locally bounded functions defined on the space C[-r,0], and X(u);u in [t-r,t] denotes the segment of the values of X(u) for time points u in the interval [t,t-r]. Our aim is to construct a sequence of discrete time series Xh of higher order, such that Xh converges weakly to the solution X of the stochastic differential delay equation as h tends to zero. On the other hand we shall establish under which conditions time series Xh of higher order converge weakly to a weak solution X of a stochastic differential delay equation. As an illustration we shall derive a weak limit of a sequence of GARCH processes of higher order. This limit tends out to be the weak solution of a stochastic differential delay equation.

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29

Wang, Xiang, und 王翔. „Model order reduction of time-delay systems with variational analysis“. Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B46604236.

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30

Wang, Shengquan. „Utilization-based delay guarantee techniques and their applications“. [College Station, Tex. : Texas A&M University, 2006. http://hdl.handle.net/1969.1/ETD-TAMU-1078.

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31

Li, Lok-man Jennifer. „Schedule delay of work trips in Hong Kong an empirical analysis /“. Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B40988041.

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32

Zhou, Ziqian. „Statistical inference of distributed delay differential equations“. Diss., University of Iowa, 2016. https://ir.uiowa.edu/etd/2173.

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In this study, we aim to develop new likelihood based method for estimating parameters of ordinary differential equations (ODEs) / delay differential equations (DDEs) models. Those models are important for modeling dynamical processes that are described in terms of their derivatives and are widely used in many fields of modern science, such as physics, chemistry, biology and social sciences. We use our new approach to study a distributed delay differential equation model, the statistical inference of which has been unexplored, to our knowledge. Estimating a distributed DDE model or ODE model with time varying coefficients results in a large number of parameters. We also apply regularization for efficient estimation of such models. We assess the performance of our new approaches using simulation and applied them to analyzing data from epidemiology and ecology.

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33

Lu, Hao. „Approximation and applications of distributed delay“. Phd thesis, INSA de Lyon, 2013. http://tel.archives-ouvertes.fr/tel-00961273.

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A distributed delay is a linear input-output operators and appears in many control problems. We investigate distributed delay and its applications. After introducing the definition and the main properties of the distributed delay, the numerical implementation problem of distributed delays is analyzed and a general method for its approximation is given. Then three applications are focused on where distributed delay appears. The first application is the stable inversion and model matching. A new class of stable inversion and model matching problem for finite dimensional linear time-invariant systems is defined. The stable inversion (resp. model matching) is an approximation of the inverse of a given model (resp. model matching), where exact inversion (resp. exact matching) is reached after a time $t=h$, which is a parameter of our procedure. The second application is concerned with stabilization and finite spectrum assignment for a class of infinite dimensional systems. The last application concerns observer synthesis for estimation or output control. For linear finite dimensional systems. A closed-loop memoryless observer by input injection is introduced. Asymptotic convergence as well as finite time convergence of the estimation are analyzed by output injection and input information via distributed delay. At last, we introduce a new class for approximation of distributed parameter systems. We work on the graph topology, and show that under some weak assumptions, such an approximation can be realized using distributed delay.

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Qiu, Jianbin. „New approaches to robust filtering design for uncertain dynamical systems with time delay /“. access full-text access abstract and table of contents, 2009. http://libweb.cityu.edu.hk/cgi-bin/ezdb/thesis.pl?phd-meem-b30082626f.pdf.

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Thesis (Ph.D.)--City University of Hong Kong, 2009.
"Submitted to Department of Manufacturing Engineering and Engineering Management in partial fulfillment of the requirements for the degree of Doctor of Philosophy." Includes bibliographical references (leaves [169]-205)

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Li, Yulan. „PREDICTIVE CONTROL FOR DYNAMIC SYSTEMS TO TRACK UNKNOWN INPUT IN THE PRESENCE OF TIME DELAY“. Master's thesis, University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4220.

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This study investigated a tracking system to trace unknown signal in the presence oftime delay. A predictive control method is proposed in order to compensate the time delay. Root locus method is applied when designing the controller, parameter setting is carried out through error and trail technique in w-plane. State space equation is derived for the system, with special state chose of tracking error. To analyze the asymptotic stability of the proposed predictive control system, the Lyapunov function is constructed. It is shown that the designed system is asymptotically stable when input signal is rather low frequency signal. In order to illustrate the system performance, simulations are done based on the data profile technique. Signal profiles including acceleration pro le, velocity pro le, and trajectory profile are listed. Based on these profiles, simulations can be carried out and results can be taken as a good estimation for practical performance of the designed predictive control system. Signal noise is quite a common phenomenon in practical control systems. Under the situation that the input signal is with measurement noise, low pass filter is designed to filter out the noise and keep the low frequency input signal. Two typical kinds of noise are specified, i.e Gaussian noise and Pink noise. Simulations results are displayed to show that the proposed predictive control with low-pass filter design can achieve better performance in the case of both kinds of noise.
M.S.E.E.
Department of Electrical and Computer Engineering
Engineering and Computer Science
Electrical Engineering

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Zhang, Liqian. „Optimal H2 model reduction for dynamic systems /“. Hong Kong : University of Hong Kong, 2000. http://sunzi.lib.hku.hk/hkuto/record.jsp?B21841548.

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37

Kalavagunta, Sushma. „Computational algorithms for stability analysis of linear systems with time-delay /“. free to MU campus, to others for purchase, 2003. http://wwwlib.umi.com/cr/mo/fullcit?p1418036.

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38

Chifan, Iustina. „Hopf Bifurcation Analysis for a Variant of the Logistic Equation with Delays“. Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/40504.

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This thesis contains some results on the behavior of a delay differential equation (DDE) with two delays, at a Hopf bifurcation, for the nonzero equilibrium, using the growth rate, r, as bifurcation parameter. This DDE is a model for population growth, incorporating a maturation delay, and a second delay in the harvesting term. Considering a Taylor expansion of the non-dimensionalized model, we find a region of stability for the nonzero equilibrium, after which we find a pair of ODEs which help define the flow on the center manifold. We then find an expression for the first Lypapunov coefficient, which changes sign, so we also find the second Lyapunov coefficient, allowing us to predict multi-stability in the model. Numerical simulations provide examples of the behavior expected. For a similar model with one delay (PMC model), we prove the Hopf bifurcation at the nonzero equilibrium is always supercritical.

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39

Xu, Hao. „Synthesis and design of PID controllers“. Texas A&M University, 2004. http://hdl.handle.net/1969.1/1480.

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controllers for discrete-time systems and time-delayed systems. By using bilinear transformation and orthogonal transformation, earlier research results obtained in the continuous-time case are extended to discrete-time situation. The complete set of stabilizing PID controllers for the discrete-time systems is thus obtained. Moreover, this set remains to be a union of convex sets when one particular parameter is fixed. Thus a method to design robust and non-fragile digital PID controllers is proposed by following a similar design procedure for the continuous-time systems. In order to find the stabilizing controller set for systems with time-delays, the relationship between the Nyquist Criterion and Pontryagins theory is investigated. The conditions under which one can correctly apply the Nyquist Criterion to time-delayed systems are derived. Then, the complete set of stabilizing PID controllers for arbitrary order LTI systems with time-delay up to a given value is obtained. Furthermore, the stability issue of a system with fixed-delay is also studied and a formula which provides complete knowledge of the distribution of the closed-loop poles is presented. Based on this formula, stabilizing P and PI controller sets for the system with fixed-delay can be computed.

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Chen, Yu Ling. „The Effects of Behavioral Skills Training on a Mother's Implementation ofConstant Time Delay for her Children with Autism and Developmental Delay“. The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555092052561576.

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41

Alwan, Mohamad. „Stability of Hybrid Singularly Perturbed Systems with Time Delay“. Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/2934.

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Hybrid singularly perturbed systems (SPSs) with time delay are considered and exponential stability of these systems is investigated. This work mainly covers switched and impulsive switched delay SPSs . Multiple Lyapunov functions technique as a tool is applied to these systems. Dwell and average dwell time approaches are used to organize the switching between subsystems (modes) so that the hybrid system is stable. Systems with all stable modes are first discussed and, after developing lemmas to ensure existence of growth rates of unstable modes, these systems are then extended to include, in addition, unstable modes. Sufficient conditions showing that impulses contribute to yield stability properties of impulsive switched systems that consist of all unstable subsystems are also established. A number of illustrative examples are presented to help motivate the study of these systems.

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42

Nelson, Tom. „ALAMOUTI SPACE-TIME CODING FOR QPSK WITH DELAY DIFFERENTIAL“. International Foundation for Telemetering, 2003. http://hdl.handle.net/10150/607483.

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International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada
Space-time coding (STC) for QPSK where the transmitted signals are received with the same delay is well known. This paper examines the case where the transmitted signals are received with a nonnegligible delay differential when the Alamouti 2x1 STC is used. Such a differential can be caused by a large spacing of the transmit antennas. In this paper, an expression for the received signal with a delay differential is derived and a decoding algorithm for that signal is developed. In addition, the performance of this new algorithm is compared to the standard Alamouti decoding algorithm for various delay differentials.

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43

Olsson, Mattias. „Contributions to Frequency Offset and Time Delay Estimation“. Licentiate thesis, Linköping : Linköping University, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-6436.

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44

McDaniel, Austin James. „The Effects of Time Delay on Noisy Systems“. Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/556867.

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We consider a general stochastic differential delay equation (SDDE) with multiplicative colored noise. We study the limit as the time delays and the correlation times of the noises go to zero at the same rate. First, we derive the limiting equation for the equation obtained by Taylor expanding the SDDE to first order in the time delays. The limiting equation contains a noise-induced drift term that depends on the ratios of the time delays to the correlation times of the noises. We prove that, under appropriate assumptions, the solution of the equation obtained by the Taylor expansion converges to the solution of this limiting equation in probability with respect to the sup norm over compact time intervals. Next, we derive the limiting equation for the SDDE and prove a similar convergence result regarding convergence of the solution of the SDDE to the solution of this limiting equation. We see that the limiting equation corresponding to the equation obtained by the Taylor expansion is an approximation of the limiting equation corresponding to the SDDE. Finally, we study the effects of time delay on a particular model of active Brownian motion.

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Olsson, Mattias. „Contributions to Delay, Gain, and Offset Estimation“. Doctoral thesis, Linköping : Department of Electrical Engineering, Linköping University, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-11826.

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46

Imaida, Takashi. „STUDIES ON BILATERAL CONTROL OF TELEOPERATOR UNDER TIME DELAY“. 京都大学 (Kyoto University), 2015. http://hdl.handle.net/2433/200503.

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47

Böhme, Christiane. „Decay rates and scattering states for wave models with time-dependent potential“. Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2011. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-70939.

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Viele Problemstellungen der Naturwissenschaften führen zur Betrachtung von nichtlinearen Wellengleichungen. Dabei ist von großem Interesse, ob zu vorgegebenen kleinen Daten Lösungen eindeutig existieren und ob diese stetig von den Daten abhängen. Hilfsmittel für diese Probleme sind Aussagen über lineare Wellengleichungen. In der vorliegenden Arbeit werden lineare Klein-Gordon Gleichungen, also Wellengleichungen mit Potentialterm, mit zeitabhängiger Masse bzgl. des Verhaltens ihrer Lösungen untersucht. Von speziellem Interesse sind Resultate mit Bezug auf verallgemeinerte Energieerhaltung und sogenannte Lp – Lq decay-Abschätzungen. Aus der Arbeit geht hervor, dass man eine Klassifizierung für Gleichungen mit fallendem Masseterm finden kann. Für Gleichungen vom Wellentyp ist der Einfluss des Potentialterms gering und die Lösungen verhalten sich wie Lösungen der Wellengleichung. Dem gegenüber stehen Gleichungen vom Klein-Gordon-Typ mit erkennbarem Einfluss des Masseterms. Ausgangspunkt für die Klassifizierung ist das kritische Verhalten der Lösungen einer skaleninvarianten Gleichung mit speziellem Masseterm.

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Gunawardana, Upul, und Kurt Kosbar. „OPTIMIZATION OF REFERENCE WAVEFORM FILTERS IN COHERENT DELAY LOCKED LOOPS“. International Foundation for Telemetering, 1999. http://hdl.handle.net/10150/606804.

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International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada
In this paper, a new coherent correlation-loop architecture for tracking direct-sequence spread-spectrum signals is proposed. In the proposed correlation loop model, the mean-square tracking error is minimized by varying the cross-correlation function between the received signal and the locally generated signal. The locally generated signal is produced by passing a replica of the transmitted signal through a linear time-invariant filter, which is termed the VCC filter. The issue of bandwidth of a correlation loop is addressed and a bandwidth definition for comparative purposes is introduced. The filter characteristics to minimize the tracking errors are determined using numerical optimization algorithms. This work demonstrates that the amplitude response of the VCC filter is a function of the input signal-to-noise ratio (SNR). In particular, the optimum filter does not replicate a differentiator at finite signal-to-noise ratio as is sometimes assumed. The optimal filter characteristics and the knowledge of the input SNR can be combined to produce a device that has very low probability of loosing lock.

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49

Pall, Goutom K. „Causes of delay in power transmission projects in Bangladesh“. Thesis, Queensland University of Technology, 2021. https://eprints.qut.edu.au/211479/1/Goutom_Pall_Thesis.pdf.

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Power transmission (PT) sits at the heart of the electric power sector linking power generation and power distribution to contribute to global economic growth. This study presents the first empirical study on causes of delays in PT projects to identify the critical delay attributes with a recommendation to minimize the delay. This research determines the overall ranking of the delay factors with the top-ranked factors being right of way problems of transmission line (TL), frequent changes in TL routes, and accessibility to the TL tower locations. Finally, recommendations are made to help minimize delay in PT projects across the globe.

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Li, Lok-man Jennifer, und 李諾文. „Schedule delay of work trips in Hong Kong: anempirical analysis“. Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B40988041.

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Dissertationen zum Thema „Timber decay“

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