Disparity among low first ionization potential elements

The elemental composition of the solar wind differs from the solar photospheric composition. Elements with low first ionization potential (FIP) appear enhanced compared to O in the solar wind relative to the respective photospheric abundances. This so-called FIP effect is different in the slow solar wind and the coronal hole wind. However, under the same plasma conditions, for elements with similar FIPs such as Mg, Si, and Fe, comparable enhancements are expected. We scrutinize the assumption that the FIP effect is always similar for different low FIP elements, namely Mg, Si, and Fe. We investigate the dependency of the FIP effect of low FIP elements on the O7+/O6+ charge state ratio depending on time and solar wind type. We order the observed FIP ratios with respect to the O7+/O6+ charge state ratio into bins and analyze separately the respective distributions of the FIP ratio of Mg, Si, and Fe for each O7+/O6+ charge state ratio bin. We observe that the FIP effect shows the same qualitative yearly behavior for Mg and Si, while Fe shows significant differences during the solar activity maximum and its declining phase. In each year, the FIP effect for Mg and Si always increases with increasing O7+/O6+ charge state ratio, but for high O7+/O6+ charge state ratios the FIP effect for Fe shows a qualitatively different behavior. During the years 2001-2006, instead of increasing with the O7+/O6+ charge state ratio, the Fe FIP ratio exhibits a broad peak. Also, the FIP distribution per O7+/O6+ charge state bin is significantly broader for Fe than for Mg and Si. These observations support the conclusion that the elemental fractionation is only partly determined by FIP. In particular, the qualitative difference behavior with increasing O7+/O6+ charge state ratio between Fe on the one hand and Mg and Si on the other hand is not yet well explained by models of fractionation

Evolution of an equatorial coronal hole structure and the released coronal hole wind stream: Carrington rotations 2039 to 2050

The Sun is a highly dynamic environment that exhibits dynamic behavior on many different timescales. In particular, coronal holes exhibit temporal and spatial variability. Signatures of these coronal dynamics are inherited by the coronal hole wind streams that originate in these regions and can effect the Earth's magnetosphere. Both the cause of the observed variabilities and how these translate to fluctuations in the in situ observed solar wind is not yet fully understood. During solar activity minimum the structure of the magnetic field typically remains stable over several Carrington rotations (CRs). But how stable is the solar magnetic field? Here, we address this question by analyzing the evolution of a coronal hole structure and the corresponding coronal hole wind stream emitted from this source region over 12 consecutive CRs in 2006. To this end, we link in situ observations of Solar Wind Ion Composition Spectrometer (SWICS) onboard the Advanced Composition Explorer (ACE) with synoptic maps of Michelson Doppler imager (MDI) on the Solar and Heliospheric Observatory (SOHO) at the photospheric level through a combination of ballistic back-mapping and a potential field source surface (PFSS) approach. Together, these track the evolution of the open field line region that is identified as the source region of a recurring coronal hole wind stream. We find that the shape of the open field line region and to some extent also the solar wind properties are influenced by surrounding more dynamic closed loop regions. We show that the freeze-in order can change within a coronal hole wind stream on small timescales and illustrate a mechanism that can cause changes in the freeze-in order. The inferred minimal temperature profile is variable even within coronal hole wind and is in particular most variable in the outer corona

Geschwindigkeitsverteilungsfunktionen von schweren Ionen im Sonnenwind bei 1 AU

From the study of the velocity distributions of solar wind ions we can draw conclusions about the formation and the development of the solar wind. Thus, it is possible to study the physical processes in the solar corona and the inner heliosphere by in situ measurements. Because their low abundance complicates their measurements heavy solar wind ions have been long neglected. Up to now observations of their velocity distributions have been solely 1D. In this thesis the 3D velocity distributions of heavy solar wind ions have been investigated. For our studies we have used data from the Solar Wind Ion Composition Spectrometer on-board the Advanced Composition Explorer. A new improved analysis technique has been developed. The new technique is adapted to analyse small count rates and thus, allows the use of high time resolutions. Based on the known 3D velocity distributions of protons and alpha particles a model for the 3D distributions of heavy ions has been developed. Furthermore, a virtual detector was implemented, that allows a comparison of the 1D observations and the 3D model. From our investigations we found that the model is capable to explain non-thermal features of the observations. In addition the influence of wave-particle interaction on the observed ion temperatures have been analysed.Das Studium der Geschwindigkeitsverteilungen von Sonnenwind Ionen erlaubt es auf die Entstehung und Entwicklung des Sonnenwindes zurück zu schließen. Es ist somit möglich durch in situ Beobachtungen die physikalischen Prozesse in der solaren Korona und der inneren Heliosphäre zu studieren. Die schweren Ionen im Sonnenwind die aufgrund ihrer geringen Häufigkeiten schwer zu Messen sind wurden hierbei lange Zeit vernachlässigt. Bislang gibt es nur eindimensionale Beobachtungen von ihren Geschwindigkeitsverteilungen. Im Rahmen dieser Arbeit wurden die dreidimensionalen Geschwindigkeitsverteilungen von schweren Ionen im Sonnenwind untersucht. Die Untersuchungen wurden mit Daten vom Solar Wind Ion Composition Spectrometer auf dem Advanced Composition Explorer durchgeführt. Ein neues verbessertes Verfahren zur Datenanalyse wurde entwickelt. Das Verfahren ist besonders geeignet für die Analyse kleiner Zählraten und erlaubt es somit hohe Zeitauflösungen zu verwenden. Anhand der bekannten dreidimensionalen Geschwindikeitsverteilungen von Protonen und Alphateilchen wurde ein Modell für die dreidimensionalen Verteilungen von schweren Ionen entwickelt. Zudem wurde ein virtueller Detektor implementiert der es erlaubt die 1D Beobachtungen mit dem 3D Modell zu vergleichen. Unsere Untersuchungen haben gezeigt, daß mit Hilfe des Modells Eigenschaften der Verteilungen die mit der Annahme einer thermischen Verteilung im Widerspruch stehen reproduziert werden können. Darüber hinaus wurde der Einfluss von Welle-Teilchen Wechselwirkung auf die beobachteten Temperaturen der Ionen untersucht

Traction Adaptive Motion Planning and Control at the Limits of Handling

In this article, we address the problem of motion planning and control at the limits of handling, under locally varying traction conditions. We propose a novel solution method where traction variations over the prediction horizon are represented by time-varying tire force constraints, derived from a predictive friction estimate. A \CFTOClong (\CFTOCshort) is solved in a receding horizon fashion, imposing these time-varying constraints. Furthermore, our method features an integrated sampling augmentation procedure that addresses the problems of infeasibility and sensitivity to local minima that arise at abrupt constraint alterations, for example, due to sudden friction changes. We validate the proposed algorithm on a Volvo FH16 heavy-duty vehicle, in a range of critical scenarios. Experimental results indicate that traction adaptive motion planning and control improves the vehicle\u27s capacity to avoid accidents, both when adapting to low local traction, by ensuring dynamic feasibility of the planned motion, and when adapting to high local traction, by realizing high traction utilization

Smart orchard sprayer to adjust pesticide dose to canopy characteristics

Apple scab (Venturia inaequalis) is one of the most endemic diseases that affect apple production worldwide. An accurate management of Plant Protection Products (PPP) together with the use of the latest technologies is one of the objectives of the EU Horizon 2020 OPTIMA project, as part of an integrated pest management (IPM) system. Optimal dose adjustment of PPP in orchards requires an accurate identification of canopy characteristics and a precise sprayer adjustment to distribute the adequate amount of active ingredient and liquid proportionally to the canopy variations. Furthermore, the possibility to use available tools and knowledge to consider the potential variability inside the parcel will lead into a reduction of the amount of PPP, which is a shared objective with the EU Farm to Fork strategy. Within the OPTIMA project a smart orchard sprayer has been developed. The system incorporates 6 ultrasonic sensors (three per side) for canopy characterization. A dedicated program developed using python allows the system to calculate canopy width and canopy density along the row. This information, together with the georeferenced location of the sprayer and the actual forward speed is used to activate the six-solenoid proportional motor-valves controlling the six different spray sections. Information about working pressure and consequently the nozzle flow rate is recorded every 1 s in order to generate the actual application map. The system is based on the adaptation of the Tree Row Volume (TRV) method established by European and Mediterranean Plant Protection Organization (EPPO, 2021) with additional information concerning canopy density. The system is linked with development of EDS (Early Detection System) and DSS (Decision Support System) within the OPTIMA project and the aim at the end of the project will be to link all the three technological developments to achieve a holistic smart sprayer.Postprint (published version