scholarly journals A Sensitivity Analysis of the SPACSYS Model

Agriculture ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 624
Author(s):  
Yan Shan ◽  
Mingbin Huang ◽  
Paul Harris ◽  
Lianhai Wu
Keyword(s):  
Sensitivity Analysis ◽  
Wheat Yield ◽  
Climatic Conditions ◽  
Water Dynamics ◽  
Ecological Modelling ◽  
Soil Conditions ◽  
Model Parameters ◽  
Nutrient Inputs ◽  
Nutrient Pool ◽  
Wheat Field

A sensitivity analysis is critical for determining the relative importance of model parameters to their influence on the simulated outputs from a process-based model. In this study, a sensitivity analysis for the SPACSYS model, first published in Ecological Modelling (Wu, et al., 2007), was conducted with respect to changes in 61 input parameters and their influence on 27 output variables. Parameter sensitivity was conducted in a ‘one at a time’ manner and objectively assessed through a single statistical diagnostic (normalized root mean square deviation) which ranked parameters according to their influence of each output variable in turn. A winter wheat field experiment provided the case study data. Two sets of weather elements to represent different climatic conditions and four different soil types were specified, where results indicated little influence on these specifications for the identification of the most sensitive parameters. Soil conditions and management were found to affect the ranking of parameter sensitivities more strongly than weather conditions for the selected outputs. Parameters related to drainage were strongly influential for simulations of soil water dynamics, yield and biomass of wheat, runoff, and leaching from soil during individual and consecutive growing years. Wheat yield and biomass simulations were sensitive to the ‘ammonium immobilised fraction’ parameter that related to soil mineralization and immobilisation. Simulations of CO2 release from the soil and soil nutrient pool changes were most sensitive to external nutrient inputs and the process of denitrification, mineralization, and decomposition. This study provides important evidence of which SPACSYS parameters require the most care in their specification. Moving forward, this evidence can help direct efficient sampling and lab analyses for increased accuracy of such parameters. Results provide a useful reference for model users on which parameters are most influential for different simulation goals, which in turn provides better informed decision making for farmers and government policy alike.

scholarly journals IMPROVEMENT OF TECHNOLOGICAL APPROVALS OF SPRING WHEAT PRODUCTION IN THE CONDITIONS OF THE RIGHT-BANK FOREST UKRAINE

2020 ◽  
pp. 64-73
Author(s):  
Mihaylo Polishuk ◽  
Ruslan Antko
Keyword(s):  
Spring Wheat ◽  
Wheat Yield ◽  
Positive Influence ◽  
Climatic Conditions ◽  
Mineral Fertilizers ◽  
Soil Conditions ◽  
Forest Steppe ◽  
Seeding Rate ◽  
Resource Potential ◽  
The Right

The article presents the effectiveness of the influence of certain agrotechnical components of the technology of growing wheat wheat in the conditions of the Right Bank Forest-steppe of Ukraine. The positive influence of application of foliar fertilization of crops is shown. The prospects of using the complex application of intensification elements are determined. It has been established that the optimization of the mode of power provides a more complete disclosure of the resource potential of plants, which increases yields. Reindeer nutrition should be considered as an element of supplementation to the soil nutrition system, primarily due to the fact that plants are able to absorb nutrients through the leaf surface only in limited quantities, with excess concentration of which possible burns or intoxication of plants. The use of foliar feeding on the background of the main fertilizer has been found to have a positive effect on productivity and quality. The role of the plant nutrition system, which allows to control the formation of grain productivity of spring wheat crops, is substantiated. It has been found that the optimization of the nutrition regime provides a fuller disclosure of the resource potential of the plants, thereby increasing the yield. Nutrition optimization provides more complete disclosure of plant resource potential, thereby increasing yields. It is determined that under the conditions of the Forest-Steppe of Ukraine the level of spring wheat yield is largely determined by the amount of rainfall that has fallen during the growing season. By optimizing the wheat's nutritional conditions, its productivity increases substantially, regardless of weather and climatic conditions. The use of mineral fertilizers, especially nitrogen in combination with phosphorus and potassium, can significantly improve the nutritional regime of the soil. The available nutrients of the plant are provided as a result of the mineralization of organic compounds by soil microorganisms and the transition of soluble mineral substances into solubility. This creates a more favorable environment for the growth and development of plants and for maintaining high soil fertility. At the end of the spring wheat vegetation, there was a redistribution of nitric and ammoniacal forms of nitrogen. It is advisable to continue research in this area and to deepen in connection with the emergence of new varieties, preparations and changes in climatic and soil conditions. Key words: spring wheat, yield, variety, sowing dates, seeding rate.

scholarly journals Climate change scenarios related to the winter wheat yields

2004 ◽  
Vol 52 (4) ◽  
pp. 125-136
Author(s):  
Zdeněk Žalud
Keyword(s):  
Climate Change ◽  
Winter Wheat ◽  
Emission Scenario ◽  
Wheat Yield ◽  
Site Effect ◽  
Climatic Conditions ◽  
Soil Conditions ◽  
Climate Change Scenarios ◽  
Time Period ◽  
Time Periods

Impact of climate change on winter wheat yields using crop growth model has been tested in this study. Simulated results show that: (1) Wheat yields tend in general to increase (40 out of 42 applied climate change scenarios) on most locations in range between 7.5–25.3% in all three time periods. In case of CCSR scenario that predicts the most severe increase of air temperature yields would be reduced by 9.6% in 2050 and by 25.8% if the A2 emission scenario would become reality. Differences between individual scenarios are large and statistically significant and especially for the more distant time periods may lead to doubts about the trend of the yield shifts. (2) Site effect upon the final quantity of climate change impact of winter wheat yield was caused mainly by site-specific differences in the present soil and climatic conditions. Specific importance of site increases with increasing severity of imposed climatic changes and culminates for emission scenario A2 and time period 2100. The sustained tendencies benefiting two warmest sites has been found as well as betters response to the change climatic conditions of sites with deeper soil profiles than those with less suitable soil conditions.

scholarly journals Using Satellite Data to Optimize Wheat Yield and Quality under Climate Change

2021 ◽  
Vol 13 (11) ◽  
pp. 2049
Author(s):  
Shilo Shiff ◽  
Itamar M. Lensky ◽  
David J. Bonfil
Keyword(s):  
Land Surface ◽  
Wheat Yield ◽  
Grain Filling ◽  
High Temperature Stress ◽  
Climatic Conditions ◽  
Google Earth ◽  
Sowing Time ◽  
Wheat Field ◽  
Yield And Quality ◽  
Grain Filling Period

Climatic conditions during the grain-filling period are a major factor affecting wheat grain yield and quality. Wheat in many semi-arid and arid areas faces high-temperature stress during this period. Remote sensing can be used to monitor both crops and environmental temperature. The objective of this study was to develop a tool to optimize field management (cultivar and sowing time). Analysis of 155 cultivar experiments (from 10 growth seasons) representing different environmental conditions revealed the required degree-days for each Israeli spring wheat cultivar to reach heading (from emergence). We developed a Google Earth Engine (GEE) app to analyze time series of gap-filled 1 km MODIS land surface temperature (LSTcont). By changing the cultivar and/or emergence date in the GEE app, the farmer can “expose” each wheat field to different climatic conditions during the grain-filling period, thereafter enabling him to choose the best cultivar to be sown in the field with the right timing. This approach is expected to reduce the number of fields that suffer from heat stress during the grain-filling period. The app can be also used to assess the effects of different global warming scenarios and to plan adaptation strategies in other regions too.

scholarly journals Global Sensitivity Analysis of a Homogenized Constrained Mixture Model of Arterial Growth and Remodeling

2021 ◽  
Author(s):  
Sebastian Brandstaeter ◽  
Sebastian L. Fuchs ◽  
Jonas Biehler ◽  
Roland C. Aydin ◽  
Wolfgang A. Wall ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Global Sensitivity Analysis ◽  
Model Parameters ◽  
Computational Studies ◽  
Growth And Remodeling ◽  
Global Sensitivity ◽  
Output Variability ◽  
Constrained Mixture ◽  
The One ◽  
Influential Parameters

AbstractGrowth and remodeling in arterial tissue have attracted considerable attention over the last decade. Mathematical models have been proposed, and computational studies with these have helped to understand the role of the different model parameters. So far it remains, however, poorly understood how much of the model output variability can be attributed to the individual input parameters and their interactions. To clarify this, we propose herein a global sensitivity analysis, based on Sobol indices, for a homogenized constrained mixture model of aortic growth and remodeling. In two representative examples, we found that 54–80% of the long term output variability resulted from only three model parameters. In our study, the two most influential parameters were the one characterizing the ability of the tissue to increase collagen production under increased stress and the one characterizing the collagen half-life time. The third most influential parameter was the one characterizing the strain-stiffening of collagen under large deformation. Our results suggest that in future computational studies it may - at least in scenarios similar to the ones studied herein - suffice to use population average values for the other parameters. Moreover, our results suggest that developing methods to measure the said three most influential parameters may be an important step towards reliable patient-specific predictions of the enlargement of abdominal aortic aneurysms in clinical practice.

scholarly journals Gaussian Processes Proxy Model with Latent Variable Models and Variogram-Based Sensitivity Analysis for Assisted History Matching

Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4290
Author(s):  
Dongmei Zhang ◽  
Yuyang Zhang ◽  
Bohou Jiang ◽  
Xinwei Jiang ◽  
Zhijiang Kang
Keyword(s):  
Sensitivity Analysis ◽  
Gaussian Processes ◽  
Latent Variable ◽  
History Matching ◽  
Latent Variable Models ◽  
High Dimensional ◽  
Model Parameters ◽  
Variable Model ◽  
Assisted History Matching ◽  
Proxy Models

Reservoir history matching is a well-known inverse problem for production prediction where enormous uncertain reservoir parameters of a reservoir numerical model are optimized by minimizing the misfit between the simulated and history production data. Gaussian Process (GP) has shown promising performance for assisted history matching due to the efficient nonparametric and nonlinear model with few model parameters to be tuned automatically. Recently introduced Gaussian Processes proxy models and Variogram Analysis of Response Surface-based sensitivity analysis (GP-VARS) uses forward and inverse Gaussian Processes (GP) based proxy models with the VARS-based sensitivity analysis to optimize the high-dimensional reservoir parameters. However, the inverse GP solution (GPIS) in GP-VARS are unsatisfactory especially for enormous reservoir parameters where the mapping from low-dimensional misfits to high-dimensional uncertain reservoir parameters could be poorly modeled by GP. To improve the performance of GP-VARS, in this paper we propose the Gaussian Processes proxy models with Latent Variable Models and VARS-based sensitivity analysis (GPLVM-VARS) where Gaussian Processes Latent Variable Model (GPLVM)-based inverse solution (GPLVMIS) instead of GP-based GPIS is provided with the inputs and outputs of GPIS reversed. The experimental results demonstrate the effectiveness of the proposed GPLVM-VARS in terms of accuracy and complexity. The source code of the proposed GPLVM-VARS is available at https://github.com/XinweiJiang/GPLVM-VARS.

scholarly journals Effects of Rootstocks on Blade Nutritional Content of Two Minority Grapevine Varieties Cultivated under Hyper-Arid Conditions in Northern Chile

Agronomy ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 327
Author(s):  
Nicolás Verdugo-Vásquez ◽  
Gastón Gutiérrez-Gamboa ◽  
Emilio Villalobos-Soublett ◽  
Andrés Zurita-Silva
Keyword(s):  
Climatic Conditions ◽  
Soil Conditions ◽  
Northern Chile ◽  
High Tolerance ◽  
Nutritional Content ◽  
Pests And Diseases ◽  
Arid Conditions ◽  
High K ◽  
Warm Weather ◽  
Nutritional Imbalance

In the 90s, as in other countries, transformation of Chilean viticulture brought about the introduction and spread of European grapevine varieties which has resulted in a massive loss of minor local and autochthonous grapevine varieties traditionally grown in several wine growing regions. Fortunately, in recent years, autochthonous and minority varieties have been revalued due to their high tolerance to pests and diseases and because of their adaptation to thermal and water stress triggered by global warming. In this study, we assessed the nutritional status of two autochthonous grapevines grafted onto four different rootstocks under the hyper-arid climatic conditions of Northern Chile over three consecutive seasons. The results showed that R32 rootstock induced high N, P, Ca, Mg and Mn levels in blades compared to Harmony rootstock. R32 rootstock and to a lesser extent, 1103 Paulsen and 140 Ruggeri rootstocks kept balanced levels of nutrients in blades collected from Moscatel Amarilla and Moscatel Negra grapevine varieties. Additionally, Harmony presented slight nutritional imbalance compared to the rest of studied rootstocks due to its low absorption of Mg, Mn, Ca and P, and its high K absorption, which was exacerbated under warm weather and salinity soil conditions. These results may provide a basis for specific cultivar/rootstock/site combinations, a nutritional guide for the viticulturists of Northern Chile, and options to diversify their production favoring the use of minority and autochthonous varieties that adapt well to hyper-arid conditions of Northern Chile.

scholarly journals Cost-effectiveness of TAS-102 plus bevacizumab versus TAS-102 monotherapy in patients with metastatic colorectal cancer

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Kiyoaki Sugiura ◽  
Yuki Seo ◽  
Takayuki Takahashi ◽  
Hideyuki Tokura ◽  
Yasuhiro Ito ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Health Care ◽  
Sensitivity Analysis ◽  
Cost Effectiveness ◽  
Combination Therapy ◽  
Metastatic Colorectal Cancer ◽  
Cost Effective ◽  
Model Parameters ◽  
Combination Regimen ◽  
The Cost

Abstract Background TAS-102 plus bevacizumab is an anticipated combination regimen for patients who have metastatic colorectal cancer. However, evidence supporting its use for this indication is limited. We compared the cost-effectiveness of TAS-102 plus bevacizumab combination therapy with TAS-102 monotherapy for patients with chemorefractory metastatic colorectal cancer. Method Markov decision modeling using treatment costs, disease-free survival, and overall survival was performed to examine the cost-effectiveness of TAS-102 plus bevacizumab combination therapy and TAS-102 monotherapy. The Japanese health care payer’s perspective was adopted. The outcomes were modeled on the basis of published literature. The incremental cost-effectiveness ratio (ICER) between the two treatment regimens was the primary outcome. Sensitivity analysis was performed and the effect of uncertainty on the model parameters were investigated. Results TAS-102 plus bevacizumab had an ICER of $21,534 per quality-adjusted life-year (QALY) gained compared with TAS-102 monotherapy. Sensitivity analysis demonstrated that TAS-102 monotherapy was more cost-effective than TAS-102 and bevacizumab combination therapy at a willingness-to-pay of under $50,000 per QALY gained. Conclusions TAS-102 and bevacizumab combination therapy is a cost-effective option for patients who have metastatic colorectal cancer in the Japanese health care system.

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