Abstract—This paper describes the application of the abrupt change detection technologies to detect the abrupt changes in the signals recorded during disturbances in the electrical power network of South Africa for disturbance analysis and relay performance monitoring. The aim is to estimate the time instants of the changes in the signal model parameters during the prefault condition, after initiation of fault, after the circuit-breaker opening and autoreclosure, etc. After these event-specific segmentations, the synchronization of the different digital fault recorder recordings are done based on the fault inception timings. The synchronized signals are segmented again. This synchronized segmentation is the first step toward automatic disturbance recognition, facilitating further complex feature vector analysis and pattern recognition. Besides, the synchronized, segmented recordings can be directly used to analyze certain kinds of disturbances and monitor the relay performance. This paper presents many practical examples from the power network in South Africa.

This thesis studies in detail the dynamics of ball screw feed drives and expands understanding of the factors that impose limitations on their performance. This knowledge is then used for developing control strategies that provide adequate command following and disturbance rejection. High performance control strategies proposed in this thesis are designed for, and implemented on, a custom-made ball screw drive. A hybrid Finite Element (FE) model for the ball screw drive is developed and coded in Matlab programming language. This FE model is employed for prediction of natural frequencies, mode shapes, and Frequency Response Functions (FRFs) of the ball screw setup. The accuracy of FRFs predicted for the ball screw mechanism alone is validated against the experimental measurements obtained through impact hammer testing. Next, the FE model for the entire test setup is validated. The dynamic characteristics of the actuator current controller are also modeled. In addition, the modal parameters of the mechanical structure are extracted from measured FRFs, which include the effects of current loop dynamics. To ensure adequate command following and disturbance rejection, three motion controllers with active vibration damping capability are developed. The first is based on the sensor averaging concept which facilitates position control of the rigid body dynamics. Active damping is added to suppress vibrations. To achieve satisfactory steady state response, integral action over the tracking error is included. The stability analysis and tuning procedure for this controller is presented together with experimental results that prove the effectiveness of this method in high-speed tracking and cutting applications. The second design uses the pole placement technique to move the real component of two of the oscillatory poles further to the left along the real axis. This yields a faster rigid body response with less vibration. However, the time delay from the current loop dynamics imposes a limitation on how much the poles can be shifted to the left without jeopardizing the system???s stability. To overcome this issue, a lead filter is designed to recover the system phase at the crossover frequency. When designing the Pole Placement Controller (PPC) and the lead filter concurrently, the objective is to minimize the load side disturbance response against the disturbances. This controller is also tested in high-speed tracking and cutting experiments. The third control method is developed around the idea of using the pole placement technique for active damping of not only the first mode of vibration, but also the second and third modes as well. A Kalman filter is designed to estimate a state vector for the system, from the control input and the position measurements obtained from the rotary and linear encoders. The state estimates are then fed back to the PPC controller. Although for this control design, promising results in terms of disturbance rejection are obtained in simulations, the Nyquist stability analysis shows that the closed loop system has poor stability margins. To improve the stability margins, the McFarlane-Glover robustness optimization method is attempted, and as a result, the stability margins are improved, but at the cost of degraded performance. The practical implementation of the third controller, was, unfortunately, not successful. This thesis concludes by addressing the problem of harmonic disturbance rejection in ball screw drives. It is shown that for cases where a ball screw drive is subject to high-frequency disturbances, the dynamic positioning accuracy of the ball screw drive can be improved significantly by adopting an additional control scheme known as Adaptive Feedforward Cancellation (AFC). Details of parameter tuning and stability analysis for AFC are presented. At the end, successful implementation and effectiveness of AFC is demonstrated in applications involving time periodic or space periodic disturbances. The conclusions drawn about the effectiveness of the AFC are based on results obtained from the high-speed tracking and end-milling experiments.

No description available.

This is the first study to investigate and provide definitive evidence that the plant pathogen Phytophthora cinnamomi is a significant threat to the mammal fauna of Western Australia. This study investigated the impact of P. cinnamomi-induced habitat disturbance and degradation on Antechinus flavipes leucogaster (yellow-footed antechinus) or mardo. Phytophthora cinnamomi is an introduced and invasive soil-borne plant pathogen that kills many common and structurally important plant species, which results in significant changes to the structural characteristics of affected areas. An evaluation of P. cinnamomi affected and unaffected areas of the northern jarrah (Eucalyptus marginata) forest revealed significant declines in the structure, composition and complexity of all areas affected by P. cinnamomi. Dieback Expression Score values ranged from a mean value of 1.88 ± 1.01 to 3.8 ± 0.41 at the P. cinnamomi affected sites, indicating a high degree of disturbance. A non-metric multidimensional scaling (MDS) analysis using 16 habitat variables identified significant (ANISOM: R=0.343, P<0.003) separation among affected and unaffected sites. A SIMPER analysis revealed that ground and shrub cover vegetation, small and total log densities, percentage leaf litter cover, and the densities of small, medium, tall single crowned and total Xanthorrhoea preissii were the greatest contributors separating affected and unaffected areas. Presently, our understanding of how P. cinnamomi affects the fauna of Western Australia is limited. This providing a unique opportunity to examine how P. cinnamomi-induced disturbance impacts upon the mardo. The mardo is a small insectivorous marsupial that is regarded as being common and a habitat generalist that occupies a broad range of forest and woodland habitats throughout the south-west of Western Australia. Until the present study, the specific habitat requirements, and therefore the factors limiting the present distribution of the mardo have received little attention. Therefore, in addition to being the first study to evaluate the impact of P. cinnamomi on Western Australian fauna, this study also provides important information about the present distribution of the mardo. Detection-nondetection mark-release surveys conducted in P. cinnamomi affected and unaffected regions of the northern jarrah forest, revealed that although, mardos were recorded at most sites, the number of mardo individuals, captures and detections were considerably lower at P. cinnamomi affected areas. Patch Occupancy analysis, using an information theoretic approach, revealed that the probability of a mardo occupying a region of the northern jarrah forest affected by P. cinnamomi ranged from a likelihood of 0.0 to 25.0%, while in contrast there was a 41.0 to 51.0% likelihood of a mardo occurring among unaffected regions. This discovery supports the hypothesis that P. cinnamomi-induced habitat disturbance impacts upon the distribution of the mardo. An evaluation of the micro-habitat features important to the mardo using Patch Occupancy modelling using an information theoretic approach identified large logs and X. preissii densities as positive contributors to the present distribution of the mardo in the northern jarrah forest. Indeed, the likelihood of a mardo occupying an area with large logs and dense patches of X. preissii ranged from 62.2% to 85.0%. In contrast, in the P. cinnamomi affected sites with lower X. preissii densities the patch occupancy probabilities ranged from 0.0% to 45.7%. Logs and X. preissii strongly contribute to the understorey and may increase nest locations and cover while offering protection from predators. Mardos may avoid P. cinnamomi affected areas because of lower X. preissii densities, which may result in fewer nest locations, reduced cover and an increased likelihood of predation. However, the results of the study must be treated as preliminary findings, therefore there may be additional environmental related or unrelated to P. cinnamomi factors that may also contribute to the occupancy rates of the mardo. Therefore, further studies and research on the ecology and biology of the mardo is strongly encouraged. Until this research is conducted, P. cinnamomi most be considered as significant threat to the conservation of the mardo. Therefore, the conservation of the mardo in the northern jarrah forest depends on limiting the spread and impact of P. cinnamomi, as well as the retention of large logs and tall X. preissii. Given that large logs and tall X. preissii contribute to the distribution of the mardo, strong consideration must be given to using these natural elements to rehabilitate the most severely disturbed areas of the northern jarrah forest. Consideration must be given to the conservation of other small and threatened mammal species that inhabit susceptible plant communities in the south-west of Western Australia. An understanding of how P. cinnamomi impacts on the mardo and other native mammals will contribute to our ability to control, protect and manage vulnerable communities and ecosystems in Western Australia. If the spread and impact of this pathogen is left unchecked, the ultimate consequence to the conservation of many small to medium native mammals that are dependant on structurally complex habitat may be devastating.

Thesis (M.A.)--York University, 2006. Graduate Programme in Psychology. / Typescript. Includes bibliographical references (leaves 51-63). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR19643

Thesis, PlanB (M.S.)--University of Wisconsin--Stout, 1999. / Includes bibliographical references.

This thesis is about the development and structure of mountain Norway spruce forest in location Koprová dolina, which is part of Tatras national park. Forest dynamic were monitored on 13 permanent research plots, every plot takes 1000 m2. Study was based on the analyses of the thicknes and age structure and the dendrochronologal analysis, which detects releases during growth. Based on results we confirmed that locations have character of natural forests, these locations are formed by strong and big-scale disturbances, but also by disturbances of medium and small strenght and scale. Results are similar with other papers and historical texts, which describes disturbances events in Koprová dolina.

x, 81 p. : ill (some col.) / This study investigates how two major groups of forest pests in North America, defoliating insects and bark beetles, influenced subsequent wildfire severity in the Booth and Bear Complex Fires. A secondary goal is to ascertain whether high-resolution plot-based vegetation data are better predictors of fire severity than lower resolution historical vegetation data. General Additive Models were used with an information-theoretic approach to determine the importance of forest insect outbreaks as predictors of fire severity. The models indicate that pest outbreaks were not significant predictors of fire severity and that high-resolution plot-based vegetation data are not superior to lower resolution historical vegetation data. Elevation and weather conditions were the most important controls of severity, while low-resolution vegetation data, slope and topographic position were of secondary importance. These results suggest defoliating insect outbreaks do not appreciably increase fire severity, though this finding should be verified in the context provided by other fires. / Committee in charge: Dr. Dan Gavin, Chairperson; Dr. Andrew Marcus, Member

The study was conducted on Mt. Hallasan (1950 a.s.l.) in South Korea. Forest plots were established along altitudinal gradient (950-1770 a.s.l.) from oak-hornbeam (Quercus serrata, C. laxiflora), to mixed-oak (Quercus mongolica, Taxus cuspidata), and fir (Abies koreana, Sorbus commixta) forests. Vascular plants were identified to species, and their total cover and covers of individual species in herb ({>} 1 m), shrub (1 - 5 m) and tree ({<} 5 m) layers estimated using Braun-Blanquet scale. Dentrended Correspondence Analyses was used to analyze relationship between environment and species composition, lifeforms spectra and plant diversity. The spatio-temporal variations in stem dispersion, radial growth, and mode of competition among trees were examined using the mapped location of trees and tree-rings. Changes in radial-growth were used to analyse stand disturbance history using 36647 measured tree-rings. Histories of radial-growth of individuals trees were further examined using visual classification to 5 different groups of growth trends. Ripley´s K-function was used to determine whether the spatial distribution pattern of trees was random, regular or clumped. Spatial size autocorrelations were used to determine the mode and extant of neighbor interactions. Spatial associations of different groups of trees and random mortality test were also computed for tree stands where Abies koreana was a dominant species.

<p>Emotional Disturbance (ED) is becoming more common in our society. The national estimates suggest that 1 in 10 youths in the United States suffer from a serious emotional disturbance (SED), a diagnoseable mental illness severe enough to cause impairments in the daily lives of students (U.S. Department of Health & Human Services, 2000 as cited in Williams 2009). This has become a challenge for teachers in the inclusive classrooms. The purpose of this study is to explore teacher’s strategies used within the classroom. Eighteen teachers from an urban public high school in the Midwest participated in an anonymous survey through Purdue Qualtrics. The results showed that all teachers have had experience working with students with ED and indicated that one-on-one support has been successful for them as a strategy. The results also indicated that 83% of teachers stated they need the most support for strategies for emotional support with 72% reporting additional strategies needed for behavioral support. </p>