TY - THES A1 - Michalczyk, Anna T1 - Modelling of nitrogen cycles in intensive winter wheat–summer maize double cropping systems in the North China Plain T1 - Modellierung von Stickstoffkreisläufen in intensiven Winterweizen–Sommermais-Doppelfruchtfolgen in der Nordchinesischen Tiefebene BT - site specific optimisation of nitrogen fertilisation with regard to nitrogen losses, water protection, productivity and regionalisation N2 - The North China Plain (NCP) is one of the most productive and intensive agricultural regions in China. High doses of mineral nitrogen (N) fertiliser, often combined with flood irrigation, are applied, resulting in N surplus, groundwater depletion and environmental pollution. The objectives of this thesis were to use the HERMES model to simulate the N cycle in winter wheat (Triticum aestivum L.)–summer maize (Zea mays L.) double crop rotations and show the performance of the HERMES model, of the new ammonia volatilisation sub-module and of the new nitrification inhibition tool in the NCP. Further objectives were to assess the models potential to save N and water on plot and county scale, as well as on short and long-term. Additionally, improved management strategies with the help of a model-based nitrogen fertiliser recommendation (NFR) and adapted irrigation, should be found. Results showed that the HERMES model performed well under growing conditions of the NCP and was able to describe the relevant processes related to soil–plant interactions concerning N and water during a 2.5 year field experiment. No differences in grain yield between the real-time model-based NFR and the other treatments of the experiments on plot scale in Quzhou County could be found. Simulations with increasing amounts of irrigation resulted in significantly higher N leaching, higher N requirements of the NFR and reduced yields. Thus, conventional flood irrigation as currently practised by the farmers bears great uncertainties and exact irrigation amounts should be known for future simulation studies. In the best-practice scenario simulation on plot-scale, N input and N leaching, but also irrigation water could be reduced strongly within 2 years. Thus, the model-based NFR in combination with adapted irrigation had the highest potential to reduce nitrate leaching, compared to farmers practice and mineral N (Nmin)-reduced treatments. Also the calibrated and validated ammonia volatilisation sub-module of the HERMES model worked well under the climatic and soil conditions of northern China. Simple ammonia volatilisation approaches gave also satisfying results compared to process-oriented approaches. During the simulation with Ammonium sulphate Nitrate with nitrification inhibitor (ASNDMPP) ammonia volatilisation was higher than in the simulation without nitrification inhibitor, while the result for nitrate leaching was the opposite. Although nitrification worked well in the model, nitrification-born nitrous oxide emissions should be considered in future. Results of the simulated annual long-term (31 years) N losses in whole Quzhou County in Hebei Province were 296.8 kg N ha−1 under common farmers practice treatment and 101.7 kg N ha−1 under optimised treatment including NFR and automated irrigation (OPTai). Spatial differences in simulated N losses throughout Quzhou County, could only be found due to different N inputs. Simulations of an optimised treatment, could save on average more than 260 kg N ha−1a−1 from fertiliser input and 190 kg N ha−1a−1 from N losses and around 115.7 mm a−1 of water, compared to farmers practice. These long-term simulation results showed lower N and water saving potential, compared to short-term simulations and underline the necessity of long-term simulations to overcome the effect of high initial N stocks in soil. Additionally, the OPTai worked best on clay loam soil except for a high simulated denitrification loss, while the simulations using farmers practice irrigation could not match the actual water needs resulting in yield decline, especially for winter wheat. Thus, a precise adaption of management to actual weather conditions and plant growth needs is necessary for future simulations. However, the optimised treatments did not seem to be able to maintain the soil organic matter pools, even with full crop residue input. Extra organic inputs seem to be required to maintain soil quality in the optimised treatments. HERMES is a relatively simple model, with regard to data input requirements, to simulate the N cycle. It can offer interpretation of management options on plot, on county and regional scale for extension and research staff. Also in combination with other N and water saving methods the model promises to be a useful tool. N2 - Die Nordchinesische Tiefebene (NCP) ist eine der produktivsten und intensivsten Agrarregionen Chinas. Große Düngermengen an mineralischem Stickstoff (N) und der oft in Kombination genutzten Überflutungsbewässerung führen zu Stickstoffüberflüssen, Grundwasserabsenkung und Umweltverschmutzung. Ziel dieser Arbeit war die Simulation des N-Kreislaufes in Winterweizen (Triticum aestivum L.)–Sommermais (Zea mays L.) -Doppelfruchtfolgen mit dem HERMES Modell. Weitere Ziele waren ein Test der Modellgüte, sowie das Potential des Modells aufzuzeigen, N und Wasser mit Hilfe einer modellbasierten N-Düngeempfehlung (NFR) und angepassten Bewässerungsstrategien einzusparen. Dies erfolgte auf Schlag- und Countyebene wie auch in Kurzzeit- und in Langzeitsimulationen, um verbesserte Managementstrategien für Quzhou-County in der Hebei-Provinz zu finden. Die Ergebnisse zeigten, dass das HERMES Modell gut unter den Wachstumsbedingungen der NCP funktioniert und alle relevanten Boden-Pflanze-Interaktionen während der Versuchszeit von 2,5 Jahren in Bezug auf N und Wasser beschreiben konnte. Es konnten keine Ertragsunterschiede zwischen Echtzeit modellbasierter NFR und anderen Behandlungen auf Schlagebene in Quzhou-County festgestellt werden. Simulationen mit steigenden Bewässerungsgaben ergaben signifikant höheren N-Austrag, höheren N-Bedarf der NFR und reduzierte Erträge. Daher birgt die konventionelle Überflutungsbewässerung, wie sie derzeit von den Landwirten praktiziert wird, große Unsicherheiten und genaue Bewässerungsmengen sollten für zukünftige Simulationsstudien bekannt sein. In der optimierten („best-practice“) Szenariosimulation auf Schlagebene konnte insbesondere die N-Düngung und der N-Austrag, aber auch die Bewässerung innerhalb 2 Jahre stark gesenkt werden. Daher hat die modellbasierte NFR in Kombination mit angepasster Bewässerung, im Gegensatz zu konventioneller und mineralischen N (Nmin)-reduzierter Behandlung, das höchste Potential Nitratauswaschung zu reduzieren. Auch das kalibrierte und validierte Ammoniak-Verflüchtigungs-modul des HERMES Modells funktionierte gut unter den Klima- und Bodenverhältnissen in Nordchina. Die zwei einfacheren Ammoniak-Verflüchtigungsansätze erreichten auch gute Ergebnisse, während die zwei prozessorientierten Ansätze Umwelteinflüsse besser darstellen konnten. In der Simulation mit der Ammonsulfatsalpeter-Düngung mit Nitrifikationsinhibitor (ASNDMPP) war die Ammoniakverflüchtigung höher als in der Simulation ohne Nitrifikationshemmer, während das Ergebnis für Nitratauswaschung umgekehrt war. Obwohl der Nitrifikationsansatz gut funktionierte, sollten von der Nitrifikation stammende Lachgasemissionen in Zukunft im Modell berücksichtigt werden. Im Jahresdurchschnitt lagen die simulierten Langzeit (31 Jahre) N-Verluste für eine Weizen-Mais-Doppelfruchtfolge im ganzen Quzhou-County bei 296,8 kg N ha−1 unter konventioneller Düngung und bei 101,7 kg N ha−1 unter optimierter Düngung inklusive NFR and automatischer Bewässerung (OPTai). Räumliche Unterschiede von simulierten N-Verlusten in Quzhou-County konnten nur aufgrund von unterschiedlichen N-Düngemengen gefunden werden. Simulationen einer optimierten Behandlung konnten im Durchschnitt mehr als 260 kg N ha−1a−1 an N-Düngung und 190 kg N ha−1a−1 an N-Verlusten und 115,7 mm a−1 an Wasser, im Vergleich zur konventionellen Behandlung, einsparen. Im Vergleich zu den Kurzzeitsimulationen ist es ein niedrigeres N- und Wasserreduktionspotential und unterstreicht die Notwendigkeit von Langzeitsimulationen um den Effekt von hohen Anfangs Nmin-Gehalten im Boden zu berücksichtigen. Zudem kommt, dass auf tonigem Lehm Simulationen mit konventioneller Bewässerung nicht den aktuellen Wasserbedarf decken konnten, welches zu Ertragseinbußen insbesondere für Winterweizen führte. Die OPTai Behandlung funktionierte bis auf hohe simulierte Denitrifikationsverluste auf diesem Standort am besten. Daher ist dort für zukünftige Simulationen ein an aktuelle Wetterverhältnisse und Pflanzenwachstumsbedürfnisse angepasstes Management von N und Wasser nötig. Trotzdem schienen die optimierten Behandlungen, trotz voller Strohrückgabe, die organische Bodensubstanz nicht zu erhalten. Zur Sicherung der Bodenfruchtbarkeit in den optimierten Behandlungen scheinen zusätzliche organische Düngergaben wahrscheinlich notwendig zu sein. HERMES ist ein relativ einfaches Modell, im Hinblick auf die Anforderungen an die Eingangsdaten, um den Stickstoffkreislauf zu simulieren. Es ermöglicht, Managementoptionen für Berater und Wissenschaftler auf Schlag-, County- und Regionalebene anzuwenden. Auch in Kombination mit anderen N- und Wasser-Einsparmethoden verspricht das Modell ein nützliches Instrument zu sein. KW - nitrogen KW - Stickstoff KW - simulation KW - Simulation KW - China KW - China Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-444213 ER - TY - JOUR A1 - Fritz, Amelie A1 - Makeyeva, Angelina A1 - Staub, Kaspar A1 - Groth, Detlef T1 - Influence of network properties on a migration induced secular height trend by Monte Carlo simulation JF - Journal of biological and clinical anthropology : Anthropologischer Anzeiger ; Mitteilungsorgan der Gesellschaft für Anthropologie N2 - Background: Recent research reported height biased migration of taller individuals and a Monte Carlo simulation showed that such preferential migration of taller individuals into network hubs can induce a secular trend of height. In the simulation model taller agents in the hubs raise the overall height of all individuals in the network by a community effect. However, it could be seen that the actual network structure influences the strength of this effect. In this paper the background and the influence of the network structure on the strength of the secular trend by migration is investigated. Material and methods: Three principal network types are analyzed: networks derived from street connections in Switzerland, more regular fishing net like networks and randomly generated ones. Our networks have between 10 and 152 nodes and between 20 and 307 edges connecting the nodes. Depending on the network size between 5.000 and 90.000 agents with an average height of 170 cm (SD 6.5 cm) are initially released into the network. In each iteration new agents are regenerated based on the actual average body height of the previous iteration and, to a certain proportion, corrected by body heights in the neighboring nodes. After generating new agents, a certain number of them migrated into neighbor nodes, the model let preferentially taller agents migrate into network hubs. Migration is balanced by back migration of the same number of agents from nodes with high centrality measures to less connected nodes. The latter is random as well, but not biased by the agents height. Furthermore the distribution of agents per node and their correlation to the centrality of the nodes is varied in a systematic manner. After 100 iterations, the secular trend, i.e. the gain in body height for the different networks, is investigated in relation to the network properties. Results: We observe an increase of average agent body height after 100 iterations if height biased migration is enabled. The increase rate depends on the height of the neighboring factor, the population distribution, the relationship between population in the nodes and their centrality as well as on the network topology. Networks with uniform like distributions of the agents in the nodes, uncorrelated associations between node centrality and agent number per node, as well as very heterogeneous networks with very different node centralities lead to biggest gains in average body height. Conclusion: Our simulations show, that height biased migration into network hubs can possibly contribute to the secular trend of height increase in the human population. The strength of this "tall by migration" event depends on the actual properties of the underlying network. There is a possible significance of this mechanism for social networks, when hubs are represented by individuals and edges as their personal relationships. However, the required high number of iterations to achieve significant effects in more natural network structures in our models requires further studies to test the relevance and real effect sizes in real world scenarios. KW - secular trend KW - body height KW - simulation KW - community effect KW - Monte Carlo method KW - network KW - centrality measures Y1 - 2019 U6 - https://doi.org/10.1127/anthranz/2019/1032 SN - 0003-5548 VL - 76 IS - 5 SP - 433 EP - 443 PB - Schweizerbart CY - Stuttgart ER - TY - GEN A1 - Bender, Benedict A1 - Grum, Marcus A1 - Gronau, Norbert A1 - Alfa, Attahiru A1 - Maharaj, B. T. T1 - Design of a worldwide simulation system for distributed cyber-physical production networks T2 - 2019 IEEE International Conference on Engineering, Technology and Innovation (ICE/ITMC) N2 - Modern production infrastructures of globally operating companies usually consist of multiple distributed production sites. While the organization of individual sites consisting of Industry 4.0 components itself is demanding, new questions regarding the organization and allocation of resources emerge considering the total production network. In an attempt to face the challenge of efficient distribution and processing both within and across sites, we aim to provide a hybrid simulation approach as a first step towards optimization. Using hybrid simulation allows us to include real and simulated concepts and thereby benchmark different approaches with reasonable effort. A simulation concept is conceptualized and demonstrated qualitatively using a global multi-site example. KW - production networks KW - geographical distribution KW - task realization strategies KW - Industry 4.0 KW - simulation KW - evaluation Y1 - 2019 SN - 978-1-7281-3401-7 SN - 978-1-7281-3402-4 U6 - https://doi.org/10.1109/ICE.2019.8792609 SN - 2334-315X PB - IEEE CY - New York ER -