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Combining High-Resolution Imaging,Deep Learning,and Dynamic Modeling to Separate Disease and Senescence in Wheat Canopies

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Plant Phenomics 2023年第2期5卷 295-312页

作者： Jonas Anderegg Radek Zenkl achim Walter Andreas Hund Plant Pathology Group Institute of Integrative BiologyETH ZurichZurichSwitzerland Crop Science Group Institute of Agricultural SciencesETH ZurichZurichSwitzerland

Maintenance of sufficiently healthy green leaf area after anthesis is key to ensuring an adequate assimilate supply for grain *** regulated age-related physiological senescence and various biotic and abiotic stressors drive overall greenness decay dynamics under field *** direct effects on green leaf area in terms of leaf damage,stressors often anticipate or accelerate physiological senescence,which may multiply their negative impact on grain ***,we present an image processing methodology that enables the monitoring of chlorosis and necrosis separately for ears and shoots(stems+leaves)based on deep learning models for semantic segmentation and color properties of vegetation.A vegetation segmentation model was trained using semisynthetic training data generated using image composition and generative adversarial neural networks,which greatly reduced the risk of annotation uncertainties and annotation *** of the models to image time series revealed temporal patterns of greenness decay as well as the relative contributions of chlorosis and ***-based estimation of greenness decay dynamics was highly correlated with scoring-based estimations(r≈0.9).Contrasting patterns were observed for plots with different levels of foliar diseases,particularly septoria tritici *** results suggest that tracking the chlorotic and necrotic fractions separately may enable(a)a separate quantification of the contribution of biotic stress and physiological senescence on overall green leaf area dynamics and(b)investigation of interactions between biotic stress and physiological *** high-throughput nature of our methodology paves the way to conducting genetic studies of disease resistance and tolerance.

关键词： Wheat enable image

A high-order full-discretization method using Hermite interpolation for periodic time-delayed differential equations

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Acta Mechanica Sinica 2015年第3期31卷 406-415页

作者： Yilong Liu achim Fischer Peter Eberhard Baohai Wu Key Laboratory of Contemporary Design and Integrated Manufacturing Technology Northwestern Polytechnical University Institute of Engineering and Computational Mechanics University of Stuttgart

A high-order full-discretization method （FDM） using Hermite interpolation （HFDM） is proposed and implemented for periodic systems with time delay. Both Lagrange interpolation and Hermite interpolation are used to approximate state values and delayed state values in each discretization step. The transition matrix over a single period is determined and used for stability analysis. The proposed method increases the approximation order of the semidiscretization method and the FDM without increasing the computational time. The convergence, precision, and efficiency of the proposed method are investigated using several Mathieu equations and a complex turning model as examples. Comparison shows that the proposed HFDM converges faster and uses less computational time than existing methods.

关键词： Full-discretization method Time delay -Stability Chatter

Stability analysis of a thin-walled cylinder in turning operation using the semi-discretization method

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Acta Mechanica Sinica 2014年第2期30卷 214-222页

作者： Arnab Chanda achim Fischer Peter Eberhard Santosha Kumar Dwivedy Institute of Engineering and Computational Mechanics University of Stuttgart

In this work, the stability of a flexible thin cylindrical workpiece in turning is analyzed. A process model is derived based on a finite element representation of the workpiece flexibility and a nonlinear cutting force law. Repeated cutting of the same surface due to overlapping cuts is modeled with the help of a time delay. The stability of the so obtained system of periodic delay differential equations is then determined using an approximation as a time-discrete system and Floquet theory. The time-discrete system is obtained using the semi-discretization method. The method is implemented to analyze the stability of two different workpiece models of different thicknesses for different tool positions with respect to the jaw end. It is shown that the stability chart depends on the tool position as well as on the thickness.

关键词： Machine tools Stability Chatter

Cereal area and nitrogen use efficiency are drivers of future nitrogen fertilizer consumption

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Science China(Life Sciences) 2005年第Z2期48卷 745-758页

作者： achim Dobermann Kenneth G.Cassman Department of Agronomy and Horticulture University of Nebraska-Lincoln P.O.Box 830915LincolnNE 68583-0915USA

At a global scale, cereal yields and fertilizer N consumption have increased in a near-linear fashion during the past 40 years and are highly correlated with one another. However,large differences exist in historical trends of N fertilizer usage and nitrogen use efficiency (NUE)among regions, countries, and crops. The reasons for these differences must be understood to estimate future N fertilizer requirements. Global nitrogen needs will depend on: (i) changes in cropped cereal area and the associated yield increases required to meet increasing cereal demand from population and income growth, and (ii) changes in NUE at the farm level. Our analysis indicates that the anticipated 38% increase in global cereal demand by 2025 can be met by a 30% increase in N use on cereals, provided that the steady decline in cereal harvest area is halted and the yield response to applied N can be increased by 20%. If losses of cereal cropping area continue at the rate of the past 20 years (-0.33% per year) and NUE cannot be increased substantially, a 60% increase in global N use on cereals would be required to meet cereal demand. Interventions to increase NUE and reduce N losses to the environment must be accomplished at the farm- or field-scale through a combination of improved technologies and carefully crafted local policies that contribute to the adoption of improved N management; uniform regional or national directives are unlikey to be effective at both sustaining yield increases and improving NUE. Examples from several countries show that increases in NUE at rates of 1% per year or more can be achieved if adequate investments are made in research and extension. Failure to arrest the decrease in cereal crop area and to improve NUE in the world's most important agricultural systems will likely cause severe damage to environmental services at local, regional, and global scales due to a large increase in reactive N load in the environment.

关键词： nitrogen, cereals, nitrogen use efficiency, fertilizer requirements, global food security.

Sustainable intensification of agriculture in sub-Saharan Africa:first things first!

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Frontiers of Agricultural Science and Engineering 2020年第4期7卷 376-382页

作者： Bernard VANLAUWE achim DOBERMANN International Institute of Tropical Agriculture Nairobi00100 NairobiKenya 2 International Fertilizer Association75116 ParisFrance

We both belong to a generation of soils scientists and agronomists who have spent or are spending their career trying to develop and scale better soil and crop management solutions for smallholder farmers in the *** have witnessed some successes in this,but also many ***,the work of the first author(BV)has primarily been in sub-Saharan Africa(SSA),while much of the work of the second author(AD)has been in *** both believe that there is great urgency to accelerate crop production in Africa,the region with the greatest challenges for food and nutritional security and socioeconomic *** believe that what SSA needs most now is an agronomic revolution.

关键词： soil Sustainable Africa

Improving the dynamic stability of a workpiece dominated turning process using an adaptronic tool holder

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Theoretical & Applied Mechanics Letters 2013年第1期3卷 63-70页

作者： achim Fischer Peter Eberhard Institute of Engineering and Computational Mechanics University of Stuttgart

In this contribution, inside turning of a thin-walled cylinder is investigated in simulation. Self-excited vibrations can arise due to repeated cutting of the same surface, that lead to instability.A flexible multibody system model of the system is the basis for a subsequent analysis of the stability of the process. Stability analysis is done using an approximation as a time-discrete system via the semi-discretization method. An adaptronic turning chisel comprising a piezo actuator and sensors is then used in combination with different control concepts to improve the stability of the process. The effectiveness of the different strategies is compared based on the influence on the stability charts. A classic H∞ controller based on a model of the coupled system of workpiece and tool can only yield some improvements, when an additional measurement of the workpiece displacement is added. Incorporating knowledge on the cutting process coupling workpiece and tool using a gain scheduled H∞ controller allows further improvements. However, robustness with respect to model uncertainties, notably concerning the force law, remains an issue. C 2013 The Chinese Society of Theoretical and Applie-d Mechanics. [doi：10.1063/2.1301308]

关键词： multibody dynamics vibrations stability feedback control

Li2SnO3 branched nano- and microstructures with intense and broadband white-light emission

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Nano Research 2019年第2期12卷 441-448页

作者： Miguel Garcia-Tecedor Javier Bartolome David Maestre achim Trampert Ana Cremades Dpt. Fisica de Materials Facultad de CC. Fisicas Universidad Complutense de Madrid Madrid 28040 Spain Paul-Drude-Institut fur Festkorperelektronik Hausvogteiplatz 5-7 Berlin 10117 Germany Institute of Advanced Materials (INAM) Universitat Jaume I Castello 12006 Spain Dpt. Fisica de Materiales Facultad de CC. Ftsicas Universidad Complutense de Madrid Madrid 28040 Spain

Exploiting the synergy between microstructure, morphology and dimensions by suitable nanomaterial engineeri ng, can effectively upgrade the physical properties and material performances. Li2SnO3 elongated nano- and microstructures in form of belts, wires, rods and branched structures have been fabricated by a vapor-solid method at temperatures ranging from 700 to 900℃ using metallic Sn and Li2CO3 as precursors. The achievement of these new morphologies can face challenging applications for Li2SnO3, not only in the field of energy storage, but also as building blocks in optoelectronic devices. The micro? and nanostructures grown at 700 and 800℃ correspond to monoclinic Li2SnO3, while at 900℃ complex Li2S nO/SnO2 core-shell microstructures are grow n, as con firmed by X-ray diffractio n and Rama n spectroscopy. Transmission electron microscopy reveals structural disorder related to stacking faults in some of the branched structures, which is associated with the prese nee of the low-temperature phase of L12S nO3. The luminescent resp onse of these structures is domi nated by in tense emissi ons at 2, 2.5 and 3 eV, almost completely covering the whole range of the visible light spectrum. As a result, white-light emission is obtained without the need of phosphors or complex quantum well heterostructures. Enhanced functionality in applications such as in light-emitting devices could be exploited based on the high luminescenee intensity observed in some of the analysed Li2SnO3 structures.

关键词： lithium oxides white light emitters nanostructures luminescenee

The Root Cap Determines Ethylene-Dependent Growth and Development in Maize Roots

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Molecular Plant 2008年第2期1卷 359-367页

作者： achim Hahn Roman Zimmermann Dierk Wanke Klaus Harter Hans G. Edelmann Botanisches Institut Universitfit zu Koin Gyrhofstr. 15 D-50931 Koin Germany Present address: ZMBP Pflanzenphysiologie University TQbingen Auf der Morgenstelle 1 D-72076 TQbingen Germany Institut fur Entwicklungsbiologie Universitat zu Koin Gyrhofstr. 17 D-50931 Koin Germany Institut fur Entwicklungsbiologie Universitat zu Koin Gyrhofstr. 17 D-50931 Koln Germany ZMBP Pflanzenphysiologie Universitat Tubingen Auf der Morgenstelle 1 D-72076 Tubingen Germany Present address: Biologie und ihre Didaktik Universitat Siegen D-57068 Siegen Germany

Besides providing protection against mechanical damage to the root tip, the root cap is involved in the perception and processing of diverse external and internal stimuli resulting in altered growth and development, The transduction of these stimuli includes hormonal signaling pathways such as those of auxin, ethylene and cytokinin. Here, we show that the root cap is essential for the ethylene-induced regulation of elongation growth and root hair formation in maize. Exogenously applied ethylene is no longer able to inhibit elongation growth when the root cap has been surgically removed prior to hormone treatment. Reconstitution of the cap positively correlates with the developing capacity of the roots to respond to ethylene again. In contrast, the removal of the root cap does not per se affect growth inhibition controlled by auxin and cytokinin. Furthermore, our semi-quantitative RT-PCR results support earlier findings that the maize root cap is a site of high gene expression activity with respect to sensing and responding to hormones such as ethylene, From these data, we propose a novel function of the root cap which is the establishment of competence to respond to ethylene in the distal zones of the root.

关键词： AUXIN BIOSYNTHESIS INSENSITIVE MUTANTS CELL ELONGATION

The Determinants of China's Minimum Wage Rates

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China & World Economy 2023年第3期31卷 59-91页

作者： achim Schmillen Michael Stops Dewen Wang Human Development World BankIndonesia Institute for Employment Research Germany Senior Social Protection Economist World BankChina.

We use a highly disaggregated panel of macro data and minimum wages at the county level to investigate the processes behind minimum wage adjustments in *** on random effects models,spatial econometrics techniques,and multilevel analyses,we document that a comparatively small number of economic variables-including the local price level and GDP per capita-are important determinants of minimum wage *** between adjacent counties and counties of the same administrative type,and centralized mechanisms,particularly at the provincial level,also play an important role in explaining the variance in minimum wage rates across ***,we show that China's provinces are the key players for setting minimum wage rates and that,when they do so,they are not uniform in the way they weigh different economic variables.

关键词： applied spatial econometrics China highly disaggregated macro data minimum wage setting multilevel analysis strategic interactions between subnationa governments