Untersuchungen zur automatischen Erntemaschinenführung mit Satellitennavigation und Leitlinienplanung

Die Entwicklung landwirtschaftlicher Arbeitsmaschinen ist in den letzten Jahrzehnten von einer kontinuierlichen Optimierung der Arbeitsorgane sowie einer Steigerung der Baugröße, Arbeitsbreite und der installierten Leistung gekennzeichnet. In vielen Fällen wird die herkömmliche Kombination von Ackerschlepper und angebautem, austauschbarem Gerät durch spezialisierte, für eine bestimmte Arbeit ausgelegte, selbstfahrende Arbeitsmaschinen abgelöst. Dieser Trend ist bei Erntemaschinen besonders deutlich. Die Bedienung einer Erntemaschine erfordert vom Maschinenführer eine hohe Konzentration. Einerseits muss er die häufig komplexen und zahlreichen Arbeitsorgane der Maschine bedienen und überwachen. Je nach Art der Erntemaschine muss das Erntegut entweder kontinuierlich oder intermittierend an ein Transportfahrzeug während der Fahrt übergeben werden. Neben diesen Hauptfunktionen muss der Maschinenführer andererseits lenken und sicherstellen, dass die Arbeitsbreite vollständig ausgenutzt wird und keine Fehlstellen in der Bearbeitung auftreten. Die Erntevorsätze können in Deutschland bis zu 9 m, in anderen Ländern häufig sogar noch breiter sein und sind entsprechend schlecht zu überblicken. Zusätzlich muss er die Fahrgeschwindigkeit an die lokalen Erntebedingungen anpassen. Der Maschinenführer hat auch die Aufgabe, mit einem günstigen Fahrkurs einen effizienten Ernteprozess zu gewährleisten und die Maschine am Feldrand entsprechend wieder in die richtige Spur zu führen. Diese Aufgaben werden häufig sowohl durch schlechte Sichtbedingungen, bedingt durch Gegenlicht, Staub oder Dunkelheit, als auch durch Zeitdruck, hervorgerufen durch die Wetterverhältnisse und Reifezustand des Erntegutes, zusätzlich erschwert. Wird der Maschinenführer vom Lenken und der Fahrgeschwindigkeitsanpassung durch geeignete Regeleinrichtungen entlastet, kann er sich auf die Hauptfunktionen konzentrieren und die Auslastung und die Arbeitsqualität der Erntemaschine steigern. Ziel der vorliegenden Arbeit ist die Erarbeitung von Grundlagen für automatisch geführte Erntemaschinen, die exemplarisch an einem selbstfahrenden Feldhäcksler untersucht werden. Die für die automatische Führung notwendigen Positionsdaten liefern hoch genaue Empfänger für das differenzielle Global Positioning System. Sie zeichnen sich durch eine erzielbare Ortungsgenauigkeit von wenigen Zentimetern aus und werden als einzige Positionssensoren verwendet. Das entwickelte Führungssystem gliedert sich in die Querregelung, um die seitliche Abweichung der Maschine in Bezug zu einer vorgegeben Leitlinie zu minimieren und einer kombinierten Fahrgeschwindigkeits- und Durchsatzregelung, um die Maschine trotz veränderlicher Erntebedingungen im Feld konstant auszulasten. Diesen beiden Regelaufgaben ist ein Fahrkurs übergeordnet. Es wurden Methoden entwickelt, nach denen Leitlinien für verschiedene Erntevorgänge mit einer automatisch geführten Maschine berechnet werden können. Die Querregelung basiert auf Ansätzen mit einem linearen Fahrzeugmodell. Der seitliche Versatz und die Fehlorientierung zur Leitlinie dienen als Reglereingangsgrößen. Zusätzlich werden die Fahrgeschwindigkeit und die Krümmung der Leitlinie berücksichtigt. Für die Fahrgeschwindigkeitsregelung wird angenommen, dass die ermittelte Antriebsleistung des Erntevorsatzes des Feldhäckslers ein geeignetes Maß für den Durchsatz ist. Es wurden verschiedene Verfahren untersucht, nach denen der Durchsatz mit der Fahrgeschwindigkeit geregelt werden kann. Im ersten Verfahren wurde die Soll-Fahrgeschwindigkeit direkt aus der ermittelten Antriebsleistung des Erntevorsatzes abgeleitet. Um den Zeitbedarf der Fahrgeschwindigkeitsanpassung zu reduzieren, wurde in einem zweiten Verfahren auch die Antriebsleistung, die bei der bereits geernteten Nachbarspur ortsbezogen gemessen und gespeichert wurde, herangezogen. Aus diesen Messungen wurde die zu erwartende Soll-Fahrgeschwindigkeit vor der Maschine abgeschätzt. In einem dritten Verfahren wurde die Antriebsleistung eines vorausgegangenen Arbeitsganges ortsbezogen gemessen und daraus die Soll-Fahrgeschwindigkeit der nachfolgenden, automatisch geführten Maschine berechnet. In diesem Fall sollte der Feldhäcksler Halmgut ernten, welches in einem vorangegangen Arbeitsgang mit einem Schwader zu Halmgutreihen, sogenannten Schwaden, zusammengeführt wurde. Wird bei dieser Arbeit der Leistungsbedarf und die Fahrgeschwindigkeit aufgezeichnet, so kann mit diesen Daten eine Soll-Fahrgeschwindigkeit des nachfolgenden Feldhäckslers berechnet werden. Die Regelung passt bei bekanntem Verlauf der Soll-Fahrgeschwindigkeit rechtzeitig die Fahrgeschwindigkeit anThe working devices of agricultural machines have been optimised continuously in the last decades. Additionally, the size of the machines, the working width and the installed power have been increased. The common combination of a tractor and a mounted, exchangeable implement is often replaced by specialized, self-propelled machines for one definite operation. Especially for harvesters this development can be noticed. The operation of a harvester requires a high concentration of the driver. He has to operate and monitor the complex and numerous working devices. Depending on the harvester the crop has to be transferred continuously or with interrupts to a transport vehicle. Working widths of harvester headers can reach to 9 m in Germany. In other countries they can be even exceeded. The working edge of these wide headers can be surveyed badly. Therefore, it is difficult to guide the machine in that way that the whole working width is used. Furthermore, the driver has to adjust the driving speed according to the local harvesting conditions. Regarding the harvesting process the driver has to choose an efficient course inside the field and at the headland. Bad sight conditions caused by back light, dust or darkness as well as time pressure caused by weather conditions and ripeness of the crop make the driver's tasks even more difficult. If suitable control systems steer the machine and adjust the driving speed automatically, the driver can concentrate on the main functions of the harvester. Therefore, the throughput and the working quality can be increased. The aim of this thesis is to develop the basic theory for an automatic guidance for harvesters which has to be investigated with a self-propelled forage harvester in practice. It was demanded that the positioning data which are necessary for the automatic guidance are provided by receivers for the differential Global Positioning System. They have an accuracy of a few centimetres. No other navigation sensors should be used. The developed guidance system is structured in the closed loop transversal and the closed loop longitudinal control system. The lateral control reduces the lateral offset to the guidance path and the longitudinal control keeps the throughput constant in the field with varying yields. The control plan is defined by the guidance path which describes the desired driving route and the speed of the harvester. Path planning methods have been developed and investigated for different harvest operations. Path planning methods for swath harvesting and field covering operations are presented. The driving course of the swather is recorded during operation. With these data the guidance path for the forage harvester is calculated. The path allows a harvest operation in forward motion in every case, in order to avoid problems between harvester and transport vehicles at the headland. In order to plan the guidance path for a field covering harvest operation, the field is first structured into a headland and a main operation area. The headland provides the turning area. Also neighbour areas are considered which can be passed. Therefore, soil damaging turning manoeuvres can be carried out outside the field. The main operation area is divided into further areas, so that the guidance path has as many straight parts as possible. The number of turns can be reduced in this manner. The simulation of the path planning process and an automatically guided harvester shows that 20% of the turning distance and 10% of the total distance can be saved in comparison to a manually guided harvester without path planning

Model-based scenario analysis for effective site-specific weed control on grassland sites

The site-specific management of weeds in grassland is often challenging because different weed control strategies have different trade-offs regarding the required resources and treatment efficiency. So, the question arises whether a wide tractor-based system with section control or a small agricultural robot has a higher weed control performance for a given infestation scenario. For example, a small autonomous robot moving from one weed to the next might have much shorter travel distances (and thus lower energy and time costs) than a tractor-mounted system if the locations of the weeds are relatively isolated across the field. However, if the plants are highly concentrated in small areas so-called clusters, the increased width of the tractor-mounted implement could be beneficial because of shorter travel distances and greater working width. An additional challenge is the fact that there is no complete knowledge of the weed locations. Weeds may not have been detected, for example, due to their growth stage, occlusion by other objects, or misclassification. Weed control strategies must therefore also be evaluated with regard to this issue. Thus, in addition to the driving distance, other metrics are also of interest, such as the number of plants that were actually controlled or the size of the total treatment area. We performed this investigation for the treatment of the toxic Colchicum autumnale, which had been detected in drone images of extensive grassland sites. In addition to real data, we generated and analyzed simulated weed locations using mathematical models of stochastic geometry. These offer the possibility to simulate very different spatial distributions of toxic plant locations. Different treatment strategies were then virtually tested on this data using Monte Carlo simulations and their performance was statistically evaluated.Comment: 20 pages, 9 figure

Bioavailability Studies of Acetaminophen and Nitrofurantoin

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97190/1/j.1552-4604.1974.tb02312.x.pd

Hydroclimate variability during the last 2700 years based on stalagmite multi-proxy records in the central-western Mediterranean

This study presents the first high-resolution speleothem-based hydrological reconstruction for much of the last 2.7 kyr in the central-western Mediterranean. The paleohydrological information comes from a combination of five U-Th dated stalagmites from two Mallorca island caves. Interpretations are based on high-resolution records of d18O, d13C and trace element analyses combined with information from mineralogical X-ray diffraction, fabrics and morphological features, and cave monitoring data. None of the studied stalagmites cover the whole 2.7 kyr period but they provide sufficient overlap to replicate most of the discussed climatic intervals with the exception of the Medieval Climate Anomaly (MCA), which is represented by a hiatus. Taking into account the results of five years farmed calcite collected in glass plates and cave environmental parameters, we argue that main patterns in the stalagmite geochemical records are mostly controlled by changing rates of prior calcite precipitation (PCP) that respond to hydrological changes in the region. We apply a principal component analysis to the stalagmite geochemical data set and a composite d18O record to obtain a robust regional hydrological record. This record supports wet conditions for the early Roman Period (RP), the first half of the Early Middle Ages (EMA) and the Little Ice Age (LIA), and drier conditions for the late RP, the late EMA and the entire MCA. These results are discussed in the context of other climatic and oceanographic records from the region including paleo North Atlantic Oscillation (NAO) records. This ocean-atmosphere approach suggests complex non-stationary climate patterns for the last 2.7 kyr, including the occurrence of both wetwarm and wet-cold intervals and underlying the complex interaction of factors controlling climate evolution in the region. Overall, positive (negative) NAO phases appear coincident with drier (wetter) conditions for all the examined period at decadal time-scale

Calicivirus from Novel Recovirus Genogroup in Human Diarrhea, Bangladesh

To identify unknown human viruses in the enteric tract, we examined 105 stool specimens from patients with diarrhea in Bangladesh. A novel calicivirus was identified in a sample from 1 patient and subsequently found in samples from 5 other patients. Phylogenetic analyses classified this virus within the proposed genus Recovirus

The strength of negative plant–soil feedback increases from the intraspecific to the interspecific and the functional group level

One of the processes that may play a key role in plant species coexistence and ecosystem functioning is plant–soil feedback, the effect of plants on associated soil communities and the resulting feedback on plant performance. Plant–soil feedback at the interspecific level (comparing growth on own soil with growth on soil from different species) has been studied extensively, while plant–soil feedback at the intraspecific level (comparing growth on own soil with growth on soil from different accessions within a species) has only recently gained attention. Very few studies have investigated the direction and strength of feedback among different taxonomic levels, and initial results have been inconclusive, discussing phylogeny, and morphology as possible determinants. To test our hypotheses that the strength of negative feedback on plant performance increases with increasing taxonomic level and that this relationship is explained by morphological similarities, we conducted a greenhouse experiment using species assigned to three taxonomic levels (intraspecific, interspecific, and functional group level). We measured certain fitness‐related aboveground traits and used them along literature‐derived traits to determine the influence of morphological similarities on the strength and direction of the feedback. We found that the average strength of negative feedback increased from the intraspecific over the interspecific to the functional group level. However, individual accessions and species differed in the direction and strength of the feedback. None of our results could be explained by morphological dissimilarities or individual traits. Synthesis. Our results indicate that negative plant–soil feedback is stronger if the involved plants belong to more distantly related species. We conclude that the taxonomic level is an important factor in the maintenance of plant coexistence with plant–soil feedback as a potential stabilizing mechanism and should be addressed explicitly in coexistence research, while the traits considered here seem to play a minor role

Educators' working conditions in a day care centre on ownership of a non-profit organization

Background: Working conditions of nursery school teachers have not been scrutinized thoroughly in scientific research. Only a few studies have so far examined work-load and strain in this profession. Preferably, subjective perceptions should be corroborated by data that can be quantified more objectively and accurately. The aim of the present observational field study was to evaluate pedagogical staffs' workflow. Methods: In 2009 eleven educators in a day care centre were observed throughout three complete workdays. A total of 250 working hours were recorded. Results: An educators' workday lasted on average 07:46:59 h (SD = 01:01:10 h).Within this time span, an average of 02:20:46 h (30.14%, SD = 00:28:07 h) were spent on caring, 01:44:18 h on playing (22.33%, SD = 00:54:12 h), 00:49:37 h on educational work (10.62%, SD = 00:40:09), and only 00:05:38 h on individual child contact (1.21%, SD = 00:04:58 h). Conclusion: For the first time, educators' workflow in day care centres was studied in real time. Some of the educators' self-reported problems were corroborated. The results of this study form a basis upon which further investigations can be built and measures can be developed for an overall improvement of child care

Traits of neighbouring plants and space limitation determine intraspecific trait variability in semi-arid shrublands

Understanding how intraspecific trait variability (ITV) responds to both abiotic and biotic constraints is crucial to predict how individuals are assembled in plant communities, and how they will be impacted by ongoing global environmental change.Three key functional traits [plant height, leaf area (LA) and specific leaf area (SLA)] were assessed to quantify the range of ITV of four dominant plant species along a rainfall gradient in semi-arid Mediterranean shrublands. Variance partitioning and confirmatory multilevel path analyses were used to assess the direct and indirect effects of rainfall, space limitation (crowding) and neighbouring plant traits on ITV.The direct effect of the local neighbourhood on the trait values of subordinate individuals was as strong as the effect of rainfall. The indirect effect of rainfall, however, mediated by the effect of the local neighbourhood on the trait values of subordinate individuals, was weak. Rainfall decreased the height and SLA of subordinate individuals, but increased their LA. Neighbouring plant traits were just as strong predictors as crowding in explaining changes in ITV.Synthesis. Our study provides a framework to disentangle the direct effects of abiotic factors and their indirect effects on ITV mediated by the local neighbourhood. Our results highlight that abiotic and biotic constraints are both substantial sources of trait variations at the individual level, and can blur processes underlying changes in ITV. Considering and disentangling combined sources with an individual perspective would help to refine our predictions for community assembly and functional ecology

Regulation of T Cell Priming by Lymphoid Stroma

The priming of immune T cells by their interaction with dendritic cells (DCs) in lymph nodes (LN), one of the early events in productive adaptive immune responses, occurs on a scaffold of lymphoid stromal cells, which have largely been seen as support cells or sources of chemokines and homeostatic growth factors. Here we show that murine fibroblastic reticular cells (FRCs), isolated from LN of B6 mice, play a more direct role in the immune response by sensing and modulating T cell activation through their upregulation of inducible nitric oxide synthase (iNOS) in response to early T cell IFNγ production. Stromal iNOS, which only functions in very close proximity, attenuates responses to inflammatory DC immunization but not to other priming regimens and preferentially affects Th1 cells rather than Th2. The resultant nitric oxide production does not affect T cell-DC coupling or initial calcium signaling, but restricts homotypic T cell clustering, cell cycle progression, and proliferation. Stromal feedback inhibition thus provides basal attenuation of T cell responses, particularly those characterized by strong local inflammatory cues