No description available.

Landings are an integral part of New Zealand Harvest operations where extracted trees are processed into logs and loaded out onto trucks. Forest owners need to balance the cost and environmental considerations when designing and constructing landings, with the productivity and safety of the harvesting crew that will use the landing. The objective of this study is to gain a greater understanding of landing size and how they affect forest harvest operations. This study investigates the relationship between landing size and processing delays. A time study was carried out for ten harvest operations predominantly in the lower North Island. The time study recorded all delays on the processing task of measuring and cutting stems into logs. The delays were then categorised so that only processing delays that are influenced by the size of the landing remained. These processing delays were then expressed per m3 and used as the response variable in regression analysis to test their correlation against landing size and a range of other predictor variables. A very strong, linear relationship between processing delays per m3 and actual landing size was found. This indicates that harvest operations on smaller landings exhibited higher delays per m3 than those on larger landings. Loading of the deck was the most significant processing delay; this is a direct result of not having enough room for surge piles as delimbing was not able to be carried out during loader downtime. The significance of the relationships developed in this study can help forest owners realise the implications of building landings that are too small for the intended purpose. Not only will small landings affect productivity, but have the potential to financially affect the forest owner also.

Landings are an integral part of New Zealand Harvest operations where extracted trees are processed into logs and loaded out onto trucks. Forest owners need to balance the cost and environmental considerations when designing and constructing landings, with the productivity and safety of the harvesting crew that will use the landing. The objective of this study is to gain a greater understanding of landing size and how they affect forest harvest operations. This study investigates the relationship between landing size and processing delays. A time study was carried out for ten harvest operations predominantly in the lower North Island. The time study recorded all delays on the processing task of measuring and cutting stems into logs. The delays were then categorised so that only processing delays that are influenced by the size of the landing remained. These processing delays were then expressed per m³ and used as the response variable in regression analysis to test their correlation against landing size and a range of other predictor variables. A very strong, linear relationship between processing delays per m3 and actual landing size was found. This indicates that harvest operations on smaller landings exhibited higher delays per m3 than those on larger landings. Loading of the deck was the most significant processing delay; this is a direct result of not having enough room for surge piles as delimbing was not able to be carried out during loader downtime. The significance of the relationships developed in this study can help forest owners realise the implications of building landings that are too small for the intended purpose. Not only will small landings affect productivity, but have the potential to financially affect the forest owner also.

No description available.

Objective Establish normative values for knee valgus angle during drop jump and step landings. Design Observational. Setting University biomechanics laboratory. Participants 100 physically active asymptomatic individuals (50 male, 50 female) aged 18–28 years old. Main outcome measures Knee valgus angle during drop jump and step landings. Results There were no differences between genders during the step landing task (p < 0.12) but there were differences during the drop jump landing task (p < 0.048). Both males and females showed no significant differences between sides for either of the tasks (p > 0.05) or between the valgus angle generated for either of the tasks (p > 0.05). Conclusion It would appear in order to be regarded as an average “normal” performance during a drop jump landing task knee valgus angle should be symmetrical and in the range of 7–13° for females and 3–8° for males. For a unilateral step landing task knee valgus angle should be symmetrical and in the range of 5–12° for females and 1–9° for males.

Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: With a view to future ship deck landings, a moving platform landing algorithm for an unmanned autonomous helicopter was successfully designed and a number of systems were developed in order to implement the landing algorithm. Through a combination of an MCA-based ship motion prediction algorithm and the appropriate analysis of platform motion criteria, a system was developed which can identify valid landing opportunities in real ship motion data recorded at sea state 4 for up to 5 s into the future with a 75% success rate. The bandwidth of the heave motion estimator and controller of the helicopter were increased by the implementation of GPS latency compensation, and velocity and acceleration feed forward terms respectively. The resulting bandwidth of at least 0.2 Hz is sufficient to track the heave motion of a platform which is simulating the motion of a ship at sea state 4 or lower. After the various systems were integrated they were coordinated in a landing state machine. A stationary platform landing was demonstrated successfully during flight tests, verifying the functionality of the landing state machine and the integration of the system. Landings on a platform simulating the motion of a ship at sea state 4 were demonstrated successfully in hardware-in-the-loop simulations. / AFRIKAANSE OPSOMMING: Met die oog op toekomstige skip dek landings, is 'n bewegende platformlandingsalgoritme vir 'n onbemande outonome helikopter suksesvol ontwerp en 'n aantal stelsels ontwikkel om die landingsalgoritme te implementeer. Deur 'n kombinasie van 'n MCA-gebaseerde skipbewegingvoorspellingsalgoritme en die toepaslike ontleding van platformbewegingkriteria, is 'n stelsel ontwikkel wat geldige landingsgeleenthede in realeskipbewegingsdata kan identifiseer. Vir skipbewegingsdata wat by seetoestand 4 opgeneem is kan landingsgeleenthede 5 s in die toekoms met ‘n 75% sekerheid identifiseer word. Die bandwydte van die afgeebewegingafskatter en beheerder van die helikopter is deur die implementering van GPS vertragingkompensasie, en snelheid en versnelling vorentoe-voer terme onderskeidelik verhoog. Die gevolglike bandwydte van minstens 0.2 Hz is voldoende om die afgeebeweging van 'n platform te volg wat die beweging van 'n skip by seetoestand 4 of laer simuleer. Nadat die stelsels geïntegreer is is hulle gekoördineer in 'n landingtoestandsmasjien. 'n Stilstaande platform landing is suksesvol gedemonstreer tydens vlugtoetse, wat die funksionaliteit van die landingtoestandsmasjien en die integrasie van die stelsel bewys. Landings op 'n platform wat die beweging van 'n skip by seetoestand 4 simuleer is suksesvol in hardeware-in-die-lus simulasies gedemonstreer.

Cooperation is increasingly being applied in the control of interconnected multi-agent systems, and it introduces many benefits. In particular, cooperation can improve the efficiency of many types of missions, and adds flexibility and robustness against external disturbances or unknown obstacles. This thesis investigates cooperative maneuvers for aerial vehicles autonomously landing on moving platforms, and how to safely and robustly perform such landings on a real system subject to a variety of disturbances and physical and computational constraints. Two specific examples are considered: the landing of a fixed-wing drone on top of a moving ground carriage; and the landing of a quadcopter on a boat. The maneuvers are executed in a cooperative manner where both vehicles are allowed to take actions to reach their common objective while avoiding safety based spatial constraints. Applications of such systems can be found in, for example, autonomous deliveries, emergency landings, and search and rescue missions. Particular challenges of cooperative landing maneuvers include the heterogeneous and nonlinear dynamics, the coupled control, the sensitivity to disturbances, and the safety criticality of performing a high-velocity landing maneuver. The thesis suggests the design of a cooperative control algorithm for performing autonomous and cooperative landings. The algorithm is based on model predictive control, an optimization-based method where at every sampling instant a finite-horizon optimal control problem is solved. The advantages of applying this control method in this setting arise from its ability to include explicit dynamic equations, constraints, and disturbances directly in the computation of the control inputs. It is shown how the resulting optimization problem of the autonomous landing controller can be decoupled into a horizontal and a vertical sub-problem, a finding which significantly increases the efficiency of the algorithm. The algorithm is derived for two different autonomous landing systems, which are subsequently implemented in realistic simulations and on a drone for real-world flight tests. The results demonstrate both that the controller is practically implementable on real systems with computational limitations, and that the suggested controller can successfully be used to perform the cooperative landing under the influence of external disturbances and under the constraint of various safety requirements. / Samarbete tillämpas i allt högre utsträckning vid reglering av sammankopplade multiagentsystem, vilket medför både ökad robusthet och flexibilitet mot yttre störningar, samt att många typer av uppgifter kan utföras mer effektivt. Denna licentiatavhandling behandlar kooperativa och autonoma landningar av drönare på mobila landingsplatformar, och undersöker hur sådana landningar kan implementeras på ett verkligt system som påverkas av externa störningar och som samtidigt arbetar under fysiska och beräkningsmässiga begränsningar. Två exempel betraktas särskilt: först landingen av ett autonomt flygplan på en bil, därefter landning av en quadcopter på en båt. Landningarna utförs kooperativt, vilket innebär att båda fordonen har möjlighet att påverka systemet för att fullborda landningen. Denna typ av system har applikationer bland annat inom autonoma leveranser, nödlandningar, samt inom eftersöknings- och räddningsuppdrag. Forskningen motiveras av ett behov av effektiva och säkra autonoma landingsmanövrar, för fordon med heterogen och komplex dynamik som samtidigt måste uppfylla en mängd säkerhetsvillkor. I avhandlingen härleds  kooperativa regleralgoritmer för landningsmanövern. Reglermetoden som appliceras är modell-prediktiv reglerteknik, en optimeringsbaserad metod under vilken ett optimalt reglerproblem med ändlig horisont löses  varje samplingsperiod. Denna metod tillför här fördelar såsom explicit hantering av systemdynamik, och direkt inkludering av störningshantering och bivillkor vid beräkning av insignaler. På så sätt kan vi direkt i optimeringslösaren hantera säkerhetsvillkor och externa störningar. Det visas även hur lösningstiden för optimeringen kan effektiviseras genom att separera den horisontella och den vertikala dynamiken till två subproblem som löses sekvensiellt. Algoritmen implementeras därefter för två olika landingssystem, för att därefter tillämpas och utvärderas i realistiska simuleringsmiljöer med olika typer av störningar, samt med flygtester på en verklig plattform. Resultaten visar dels att reglermetoden ger önskade resultat med avseende både på störningshantering och uppfyllande av bivillkor från säkerhetskrav, och dels att algoritmen är praktiskt implementerbar även på system med begränsad beräkningskraft. / <p>QC 20190315</p>

La compréhension et la gestion des écosystèmes requièrent un maximum de connaissances sur les dynamiques de populations. Depuis 2007, la taille de la sardine (Sardina pilchardus) et de l’anchois (Engraulis encrasicolus) dans le Golfe du Lion a chuté tandis qu’au même moment, la population de sprat, qui a une faible valeur commerciale, a fortement augmenté. Les très forts enjeux économiques autour de ces espèces ont conduit au projet de recherche « EcoPelGol » dans lequel se situe cette étude portant sur les changements observés. La condition corporelle, la croissance ainsi que la structure en âge et en taille des sardines, des anchois et en partie des sprats ont été analysées sur les vingt dernières années. Alors qu’en 2005-2007, la situation semblait optimale pour les anchois et les sardines (taille et condition élevées), celle-ci s’est considérablement dégradée depuis 2008, l’anchois et la sardine étant significativement plus petits et plus maigres. De plus, une diminution de l’âge et de la croissance a été observée chez la sardine. Nous avons ensuite caractérisé les fluctuations des débarquements historiques (1865-2013) de l’anchois, de la sardine et du maquereau. La chute récente des débarquements a été mise en exergue, avec une situation inédite où la sardine est actuellement moins débarquée qu’avant les années 60, date à laquelle les débarquements ont fortement augmenté suite à un accroissement conséquent de l’effort de pêche. Bien que la majorité de la variance dans les séries de débarquements semble être engendré par les changements de l’effort de pêche, nous avons également observé une relation entre les débarquements et l’indice « Atlantic Multidecadal Oscillation » pour l’anchois et la sardine et avec le « Western Mediterranean Oscillation » pour l'anchois. Dans une troisième analyse, la pression de prédation du thon rouge sur l’anchois, la sardine et le sprat a été estimée pour voir si l’accroissement de la population du thon depuis 2007 lié à de nouvelle mesures de gestion a pu impacté les poissons petits pélagiques. Mais bien que la sardine et l’anchois soient les proies principales du thon, moins de 2% de leurs populations ont été consommés chaque année entre 2011-2013, et ce, sans sélectivité sur la taille de ces proies de la part du thon. Ainsi, le thon rouge n’a pas pu avoir un impact significatif sur la structure en taille ou les abondances des petits pélagiques. Dans le chapitre final, nous avons considéré la possible influence de pathogènes. Des analyses globales dirigées vers la détection des parasites, des bactéries et des virus ont été effectuées tout au long de l’année et ont révélées la présence ponctuelle et relativement faible de bactéries des genres Tenacibaculum et Vibrio et celle systématique de microparasites. Malgré l’impossibilité d’exclure leur pathogénicité, aucune lésion tissulaire n’a été attribuée à ces organismes, réduisant fortement la probabilité d’une épizootie. Nos travaux indiquent que les mécanismes « top-down », des pathogènes ou encore la pêche ne sont probablement pas les facteurs clés pour expliquer les changements observés chez les poissons petites pélagiques. À l'opposé, certains paramètres environnementaux ont expliqué une partie de la variabilité dans la condition corporelle des poissons et leurs débarquements. Nous concluons donc qu’un contrôle « bottom-up », et particulièrement un changement dans la quantité et/ou qualité du zooplancton, peut être la cause des phénomènes dans les populations des poissons petits pélagiques. Si cette thèse permet une avancée dans la compréhension de leur dynamique, des analyses complémentaires seront nécessaires pour confirmer notre hypothèse principale et pour estimer l’influence des autres facteurs agissant potentiellement en synergie. / Knowledge on population dynamics is key to the improvement of management and the understanding of ecosystem functioning. Since 2007, the size of sardine (Sardina pilchardus) and anchovy (Engraulis encrasicolus) in the Gulf of Lions (NW Mediterranean) has severely decreased, which has strongly affected the fisheries. Simultaneously, the commercially uninteresting sprat population increased remarkably. As the economic and ecological stakes are high, the EcoPelGol project of which this PhD is part was established. We first analysed the sardine, anchovy and (partially) sprat population for changes in body condition, growth and size and age structure over the last 20 years. We concluded that sardine and anchovy have had from 2008 onwards a distinctively poor body condition and size, and that sardine have also showed a concurrent decrease in age and growth. In contrast, both species were in optimal and average “health” during 2005-2007 and 1992-2004, respectively. Subsequently, historical landings of sardine, anchovy and mackerel were considered (1865-2013), of which the fluctuations were characterised and statistically related to environmental variables. The recent dramatic landings decrease was put into perspective, as for example sardine is now for the first time landed less than before the 1960s, when a big probably effort-related upsurge occurred. Despite most of the variability being explained by what looks like changes in fishing effort, a link was found between the sardine and anchovy landings and the Atlantic Multidecadal Oscillation and the anchovy landings and the Western Mediterranean Oscillation. Next, as a management associated bluefin tuna increase also happened since 2007, its predation pressure on all three small pelagic species was estimated. We concluded that although sardine and anchovy are bluefin tuna’s main prey items, less than 2% of each population (including sprat) was consumed annually during 2011-2013 and that there was no clear size selectivity. Thus, tuna could not have had a noticeable impact on the population abundance or size structure of the small pelagics. In the last chapter, an epizootic disease was considered. An all-embracing approach directed towards the all-year round detection of both general and specific parasites, bacteria and viruses revealed the mostly temporal and not necessarily high occurrence of only three groups: microparasites, Vibrio spp. (sometimes determined as Vibrio alginolyticus) and bacteria of the genus Tenacibaculum. Although we could not exclude their pathogenicity, significant tissue damage at a cellular or macroscopic level was never observed, making the disease hypothesis less likely. Thus, we considered several hypotheses and indicated that top-down control (through Bluefin tuna predation), pathogens and fisheries are unlikely to be main drivers. In contrast, some environmental parameters explained a part of the variability in fish condition and landings. After a final discussion on all probable theories we concluded that a bottom-up control, such as especially a planktonic change in quantity and/or quality, might be on the basis of the observed changes. Although this work is a great step towards the understanding of the small pelagic dynamics in the Gulf of Lions, further investigations will still be needed to confirm our main hypothesis and to estimate the potential synergetic effect of other drivers.

The final master´s thesis targets to create concept study of VFR airport.This airport should be build up in southeast part of Czech republic, in the vicinity of the town Valašské Klobouky. In this work there are explained essential terms and definitions refered to basic rules and law. There are explained also civil aviation law and requirements of L14 regulations. Aeroclub is submitter of this work. It establishes basic conditions for airport area searching. The length of the runway is influenced mainly by performance of used aircrafts. It was impossible to find any acceptable field in searched area. There is a posibility how to solve this problem. There can be build up a runway for take-off and landings of small aeroplanes. In the second part of this thesis there are defined basic requirements on these fields. These requirements are applicated on chosen field. At the end of this thesis there is propounded an option how to dislocate runway, taxiways, aprons, hangars and other buildings.