Echtzeitregelung der Applikationsmenge bei der Herbizidanwendung mit Hilfe eines Kamerasensors

Am Leibniz-Institut für Agrartechnik wurde in Zusammenarbeit mit den Firmen SYMACON Bildverarbeitung GmbH Barleben und Müller-Elektronik GmbH & Co. KG Salzkotten ein sensorgesteuertes Feldspritzensystem zur Applikation von Pflanzenschutzmitteln entwickelt.Bei engstehenden Reihenkulturen wie Getreide erfolgt die Unkrauterfassung in der Fahrspur. Systembedingt wird nicht zwischen Unkraut und Kulturpflanze unterschieden. Dadurch ist ein langer Einsatzzeitraum des Systems gegeben, zumal eine Unterscheidung von Kulturpflanze und Unkraut je nach Überlappungsgrad im fortgeschrittenen Wachstumsstadium äußerst schwierig bzw. nicht mehr möglich ist. Situationsbedingt können als Regelparameter die Unkrautanzahl (frühe Wachstumsstadien des Unkrautes) oder der Unkrautdeckungsgrad (späte Wachstumsstadien) verwendet werden. Auf Grund der mechanischen Trägheit der Feldspritze beim Erreichen des Sollwertes der Applikationsmenge (Druckanpassung innerhalb des Regelbereiches der Düsen) ist ein gewisser Abstand zwischen dem Sensor und dem Spritzbalken notwendig. Daher ist der Kamerasensor am Frontdreipunkt des Traktors positioniert. Feldspritzen mit einer schnellen kontinuierlichen Regelung der Applikationsmenge, die eine Sensorpositionierung am Spritzbalken erlauben, werden zurzeit nicht produziert.Im Unterschied zu anderen am Markt verfügbaren bzw. in Entwicklung befindlichen sensorgestützten Applikationssystemen, wo Düsen bzw. Teilbreiten an- und abgeschaltet werden, wird entsprechend einer definierten Regelfunktion während der Fahrt die Applikationsmenge entsprechend dem Sensorsignal variiert. In Feldbereichen, in denen die Verunkrautung einen bestimmten Schwellenwert übersteigt, wird mit der betriebsüblichen Menge gespritzt, während in Bereichen ohne Unkraut bis zu 50 % reduziert wird. Zwischen 50 % bis 100 % erfolgt eine proportionale Anpassung der Applikationsmenge. Im Gegensatz zu einer Düsenbzw. Teilbreitenschaltung „an/aus“ bleiben bei einer kontinuierlichen Regelung keine Feldbereiche unbehandelt. Die Gefahr einer ungehinderten Unkrautentwicklung bis hin zur Samenbildung ist nicht gegeben.Im Herbst 2009 wurde mit dem sensorgesteuerten Spritzensystem in einem 26 ha großen Wintergerstenfeld eines Landwirtschaftsbetriebes eine Herbizidapplikation durchgeführt. Die Mitteleinsparung belief sich auf 20 %.Stichwörter: Multispektralkamera, präzise Unkrautkontrolle, Unkrautsensor, variable AufwandmengenOnline variable rate herbicide application using a camera sensorIn cooperation with the two companies SYMACON Bildverarbeitung GmbH Barleben and Müller-Elektronik GmbH & Co. KG Salzkotten a sensor controlled field sprayer for precise plant protection was developed at the Leibniz-institute for Agricultural Engineering.In narrow seeded field crops like cereals, the weed detection is done within the tramlines. Because of the way the system operates, there is no discrimination between cultivated crops and weeds. In later growth stages, crop and weed are overlapping and discrimination within the plant stand becomes difficult or even impossible. Situational, the weed number (early growth stages) or the weed coverage level (late growth stages) can be used as parameter to control the field sprayer. The sensor is positioned at the front three point linkage of the tractor. Field sprayers with a fast adaption of the application rate are not yet commercially available.In contrast to other “on/off” sensor controlled application systems which are on the market or under development, the application rate in the presented technology is in- or decreased according to the sensor signal. At heavy weed infested sites of the field, the customary application rate is sprayed. It is reduced up to 50 % at sites with low weed pressure. Between the volume of 50 % and 100 %, the application rate is proportional adapted to the weed infestation. In contrast to the “on/off” switching of single nozzles or boom sections, no sites are left unsprayed using the variable rate approach. There is no risk of unobstructed weed development or seed setting.In autumn 2009, a 26 ha winter barley field on a farm was sprayed against weeds with the sensor controlled field sprayer. The product Falkon® was used with the dosage of 1 l/ha. The spray volume was varied between 100 and 200 l/ha. The product savings were on average 20 %. Keywords: Multispectral camera, precise weed control, sensor-controlled sprayer, weed sensor

5. Freiburger Bildungsbericht. Bildung für nachhaltige Entwicklung

Der vorliegende 5. Freiburger Bildungsbericht mit dem Schwerpunkt Bildung für nachhaltige Entwicklung (BNE) gibt wertvolle Impulse. Dieser Bericht ist in vielerlei Hinsicht ungewöhnlich. Zunächst ist er bundesweit der erste Bildungsbericht, der sich ausschließlich mit diesem Thema befasst; diese Tatsache war Herausforderung und Chance zugleich. Es konnte nicht auf bestehende gute Beispiele zurückgegriffen werden, sondern die Inhalte mussten selbst erarbeitet werden. Eine weitere Besonderheit des Berichtes liegt in seinem partizipativen Charakter. Von der Konzepterstellung bis hin zu den Datenerhebungsverfahren waren Freiburgerinnen und Freiburger eingebunden. (DIPF/Orig.

Multiplicity dependence of jet-like two-particle correlations in p-Pb collisions at sNN\sqrt{s_{NN}} = 5.02 TeV

Two-particle angular correlations between unidentified charged trigger and associated particles are measured by the ALICE detector in p-Pb collisions at a nucleon-nucleon centre-of-mass energy of 5.02 TeV. The transverse-momentum range 0.7 $< p_{\rm{T}, assoc} < p_{\rm{T}, trig} <$ 5.0 GeV/$c$ is examined, to include correlations induced by jets originating from low momen\-tum-transfer scatterings (minijets). The correlations expressed as associated yield per trigger particle are obtained in the pseudorapidity range $|\eta|<0.9$. The near-side long-range pseudorapidity correlations observed in high-multiplicity p-Pb collisions are subtracted from both near-side short-range and away-side correlations in order to remove the non-jet-like components. The yields in the jet-like peaks are found to be invariant with event multiplicity with the exception of events with low multiplicity. This invariance is consistent with the particles being produced via the incoherent fragmentation of multiple parton--parton scatterings, while the yield related to the previously observed ridge structures is not jet-related. The number of uncorrelated sources of particle production is found to increase linearly with multiplicity, suggesting no saturation of the number of multi-parton interactions even in the highest multiplicity p-Pb collisions. Further, the number scales in the intermediate multiplicity region with the number of binary nucleon-nucleon collisions estimated with a Glauber Monte-Carlo simulation.Comment: 23 pages, 6 captioned figures, 1 table, authors from page 17, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/161

Anisotropic flow of charged hadrons, pions and (anti-)protons measured at high transverse momentum in Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm NN}}=2.76 TeV

The elliptic, $v_2$, triangular, $v_3$, and quadrangular, $v_4$, azimuthal anisotropic flow coefficients are measured for unidentified charged particles, pions and (anti-)protons in Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV with the ALICE detector at the Large Hadron Collider. Results obtained with the event plane and four-particle cumulant methods are reported for the pseudo-rapidity range $|\eta|<0.8$ at different collision centralities and as a function of transverse momentum, $p_{\rm T}$, out to $p_{\rm T}=20$ GeV/$c$. The observed non-zero elliptic and triangular flow depends only weakly on transverse momentum for $p_{\rm T}>8$ GeV/$c$. The small $p_{\rm T}$ dependence of the difference between elliptic flow results obtained from the event plane and four-particle cumulant methods suggests a common origin of flow fluctuations up to $p_{\rm T}=8$ GeV/$c$. The magnitude of the (anti-)proton elliptic and triangular flow is larger than that of pions out to at least $p_{\rm T}=8$ GeV/$c$ indicating that the particle type dependence persists out to high $p_{\rm T}$.Comment: 16 pages, 5 captioned figures, authors from page 11, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/186

Centrality dependence of charged particle production at large transverse momentum in Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm{NN}}} = 2.76 TeV

The inclusive transverse momentum ($p_{\rm T}$) distributions of primary charged particles are measured in the pseudo-rapidity range $|\eta|<0.8$ as a function of event centrality in Pb-Pb collisions at $\sqrt{s_{\rm{NN}}}=2.76$ TeV with ALICE at the LHC. The data are presented in the $p_{\rm T}$ range $0.15<p_{\rm T}<50$ GeV/$c$ for nine centrality intervals from 70-80% to 0-5%. The Pb-Pb spectra are presented in terms of the nuclear modification factor $R_{\rm{AA}}$ using a pp reference spectrum measured at the same collision energy. We observe that the suppression of high-$p_{\rm T}$ particles strongly depends on event centrality. In central collisions (0-5%) the yield is most suppressed with $R_{\rm{AA}}\approx0.13$ at $p_{\rm T}=6$-7 GeV/$c$. Above $p_{\rm T}=7$ GeV/$c$, there is a significant rise in the nuclear modification factor, which reaches $R_{\rm{AA}} \approx0.4$ for $p_{\rm T}>30$ GeV/$c$. In peripheral collisions (70-80%), the suppression is weaker with $R_{\rm{AA}} \approx 0.7$ almost independently of $p_{\rm T}$. The measured nuclear modification factors are compared to other measurements and model calculations.Comment: 17 pages, 4 captioned figures, 2 tables, authors from page 12, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/284

Multi-particle azimuthal correlations in p-Pb and Pb-Pb collisions at the CERN Large Hadron Collider

Measurements of multi-particle azimuthal correlations (cumulants) for charged particles in p-Pb and Pb-Pb collisions are presented. They help address the question of whether there is evidence for global, flow-like, azimuthal correlations in the p-Pb system. Comparisons are made to measurements from the larger Pb-Pb system, where such evidence is established. In particular, the second harmonic two-particle cumulants are found to decrease with multiplicity, characteristic of a dominance of few-particle correlations in p-Pb collisions. However, when a $|\Delta \eta|$ gap is placed to suppress such correlations, the two-particle cumulants begin to rise at high-multiplicity, indicating the presence of global azimuthal correlations. The Pb-Pb values are higher than the p-Pb values at similar multiplicities. In both systems, the second harmonic four-particle cumulants exhibit a transition from positive to negative values when the multiplicity increases. The negative values allow for a measurement of $v_{2}\{4\}$ to be made, which is found to be higher in Pb-Pb collisions at similar multiplicities. The second harmonic six-particle cumulants are also found to be higher in Pb-Pb collisions. In Pb-Pb collisions, we generally find $v_{2}\{4\} \simeq v_{2}\{6\}\neq 0$ which is indicative of a Bessel-Gaussian function for the $v_{2}$ distribution. For very high-multiplicity Pb-Pb collisions, we observe that the four- and six-particle cumulants become consistent with 0. Finally, third harmonic two-particle cumulants in p-Pb and Pb-Pb are measured. These are found to be similar for overlapping multiplicities, when a $|\Delta\eta| > 1.4$ gap is placed.Comment: 25 pages, 11 captioned figures, 3 tables, authors from page 20, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/87

Charge separation relative to the reaction plane in Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm NN}}= 2.76 TeV

Measurements of charge dependent azimuthal correlations with the ALICE detector at the LHC are reported for Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV. Two- and three-particle charge-dependent azimuthal correlations in the pseudo-rapidity range $|\eta| < 0.8$ are presented as a function of the collision centrality, particle separation in pseudo-rapidity, and transverse momentum. A clear signal compatible with a charge-dependent separation relative to the reaction plane is observed, which shows little or no collision energy dependence when compared to measurements at RHIC energies. This provides a new insight for understanding the nature of the charge dependent azimuthal correlations observed at RHIC and LHC energies.Comment: 12 pages, 3 captioned figures, authors from page 2 to 6, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/286

A note on comonotonicity and positivity of the control components of decoupled quadratic FBSDE

In this small note we are concerned with the solution of Forward-Backward Stochastic Differential Equations (FBSDE) with drivers that grow quadratically in the control component (quadratic growth FBSDE or qgFBSDE). The main theorem is a comparison result that allows comparing componentwise the signs of the control processes of two different qgFBSDE. As a byproduct one obtains conditions that allow establishing the positivity of the control process.Comment: accepted for publicatio

Measurement of charm production at central rapidity in proton-proton collisions at s=2.76\sqrt{s} = 2.76 TeV

The $p_{\rm T}$-differential production cross sections of the prompt (B feed-down subtracted) charmed mesons D$^0$, D$^+$, and D$^{*+}$ in the rapidity range $|y|<0.5$, and for transverse momentum $1< p_{\rm T} <12$ GeV/$c$, were measured in proton-proton collisions at $\sqrt{s} = 2.76$ TeV with the ALICE detector at the Large Hadron Collider. The analysis exploited the hadronic decays D$^0 \rightarrow$K$\pi$, D$^+ \rightarrow$K$\pi\pi$, D$^{*+} \rightarrow$D$^0\pi$, and their charge conjugates, and was performed on a $L_{\rm int} = 1.1$ nb$^{-1}$ event sample collected in 2011 with a minimum-bias trigger. The total charm production cross section at $\sqrt{s} = 2.76$ TeV and at 7 TeV was evaluated by extrapolating to the full phase space the $p_{\rm T}$-differential production cross sections at $\sqrt{s} = 2.76$ TeV and our previous measurements at $\sqrt{s} = 7$ TeV. The results were compared to existing measurements and to perturbative-QCD calculations. The fraction of cdbar D mesons produced in a vector state was also determined.Comment: 20 pages, 5 captioned figures, 4 tables, authors from page 15, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/307

Transverse sphericity of primary charged particles in minimum bias proton-proton collisions at s=0.9\sqrt{s}=0.9, 2.76 and 7 TeV

Measurements of the sphericity of primary charged particles in minimum bias proton--proton collisions at $\sqrt{s}=0.9$, 2.76 and 7 TeV with the ALICE detector at the LHC are presented. The observable is linearized to be collinear safe and is measured in the plane perpendicular to the beam direction using primary charged tracks with $p_{\rm T}\geq0.5$ GeV/c in $|\eta|\leq0.8$. The mean sphericity as a function of the charged particle multiplicity at mid-rapidity ($N_{\rm ch}$) is reported for events with different $p_{\rm T}$ scales ("soft" and "hard") defined by the transverse momentum of the leading particle. In addition, the mean charged particle transverse momentum versus multiplicity is presented for the different event classes, and the sphericity distributions in bins of multiplicity are presented. The data are compared with calculations of standard Monte Carlo event generators. The transverse sphericity is found to grow with multiplicity at all collision energies, with a steeper rise at low $N_{\rm ch}$, whereas the event generators show the opposite tendency. The combined study of the sphericity and the mean $p_{\rm T}$ with multiplicity indicates that most of the tested event generators produce events with higher multiplicity by generating more back-to-back jets resulting in decreased sphericity (and isotropy). The PYTHIA6 generator with tune PERUGIA-2011 exhibits a noticeable improvement in describing the data, compared to the other tested generators.Comment: 21 pages, 9 captioned figures, 3 tables, authors from page 16, published version, figures from http://aliceinfo.cern.ch/ArtSubmission/node/308