Food security remains a critical concern in Indonesia, prompting the need for adequate food availability nationwide. Maize, as a prominent staple crop, faces demand imbalances across the country. To ...address this issue, a system dynamics model is developed to analyze the dynamics of maize supply and demand in East Java. The model captures the non-linear and dynamic relationships inherent in maize production and consumption. Through a rigorous research methodology, this study presents a comprehensive system dynamics model that depicts the current state and dynamics of maize supply. The key findings shed light on the factors influencing maize availability in East Java and provide insights for policymakers to enhance food security. By utilizing a systems approach, this research contributes to the understanding of maize supply dynamics and supports the development of strategies to ensure sufficient food supply in the region.
•Mathematical model for Covid19.•SEIR model for Covid19.•Covid19 in Indonesia.•Numerical solution of SEIR model.
The Aim of this research is construct the SEIR model for COVID-19, Stability Analysis ...and numerical simulation of the SEIR model on the spread of COVID-19. The method used to construct the model is the SEIR model by considering vaccination and isolation factors as model parameters, the analysis of the model uses the generation matrix method to obtain the basic reproduction numbers and the global stability of the COVID-19 distribution model. Numerical simulation models use secondary data on the number of COVID-19 cases in Indonesia. The results obtained are the SEIR model for COVID-19; model analysis yields global stability from the spread of COVID-19; The results of the analysis also provide information if no vaccine, Indonesia is endemic COVID-19. Then the simulation results provide a prediction picture of the number of COVID-19 in Indonesia in the following days, the simulation results also show that the vaccine can accelerate COVID-19 healing and maximum isolation can slow the spread of COVID-19. The results obtained can be used as a reference for early prevention of the spread of COVID-19 in Indonesia
25 years of the WOFOST cropping systems model de Wit, Allard; Boogaard, Hendrik; Fumagalli, Davide ...
Agricultural systems,
January 2019, 2019-01-00, 2019, Letnik:
168
Journal Article
Recenzirano
Odprti dostop
The WOFOST cropping systems model has been applied operationally over the last 25 years as part of the MARS crop yield forecasting system. In this paper we provide an updated description of the model ...and reflect on the lessons learned over the last 25 years. The latter includes issues like system performance, model sensitivity, spatial model setup, parameterization and calibration approaches as well as software implementation and version management. Particularly for spatial model calibrations we provide experience and guidelines on how to execute calibrations and how to evaluate WOFOST model simulation results, particularly under conditions of limited field data availability.
As an open source model WOFOST has been a success with at least 10 different implementations of the same concept. An overview is provided for those implementations which are managed by MARS or Wageningen groups. However, the proliferation of WOFOST implementations has also led to questions on the reproducibility of results from different implementations as is demonstrated with an example from MARS. In order to certify that the different WOFOST implementations and versions available can reproduce basic sets of inputs and outputs we make available a large set of test cases as appendix to this publication.
Finally, new methodological extensions have been added to WOFOST in simulating the impact of nutrients limitations, extreme events and climate variability. Also, a difference is made in the operational and scientific versions of WOFOST with different licensing models and possible revenue generation. Capitalizing both on academic development as well as model testing in real-world situations will help to enable new applications of the WOFOST model in precision agriculture and smart farming.
•An updated description of the WOFOST model is provided•Guidelines for (spatial) calibration of WOFOST are provided•Current implementations of the model are described and issues with model proliferation are raised•New development and model extensions are described•A set of reference results is published that can be used to certify any WOFOST implementation.
Potential consequences of climate change on crop production can be studied using mechanistic crop simulation models. While a broad variety of maize simulation models exist, it is not known whether ...different models diverge on grain yield responses to changes in climatic factors, or whether they agree in their general trends related to phenology, growth, and yield. With the goal of analyzing the sensitivity of simulated yields to changes in temperature and atmospheric carbon dioxide concentrations CO2, we present the largest maize crop model intercomparison to date, including 23 different models. These models were evaluated for four locations representing a wide range of maize production conditions in the world: Lusignan (France), Ames (USA), Rio Verde (Brazil) and Morogoro (Tanzania). While individual models differed considerably in absolute yield simulation at the four sites, an ensemble of a minimum number of models was able to simulate absolute yields accurately at the four sites even with low data for calibration, thus suggesting that using an ensemble of models has merit. Temperature increase had strong negative influence on modeled yield response of roughly -0.5 Mg ha-1 per °C. Doubling CO2 from 360 to 720 µmol mol-1 increased grain yield by 7.5% on average across models and the sites. That would therefore make temperature the main factor altering maize yields at the end of this century. Furthermore, there was a large uncertainty in the yield response to CO2 among models. Model responses to temperature and CO2 did not differ whether models were simulated with low calibration information or, simulated with high level of calibration information.
We introduce LANDIS-II, a landscape model designed to simulate forest succession and disturbances. LANDIS-II builds upon and preserves the functionality of previous LANDIS forest landscape simulation ...models. LANDIS-II is distinguished by the inclusion of variable time steps for different ecological processes; our use of a rigorous development and testing process used by software engineers; and an emphasis on collaborative features including a flexible, open architecture. We detail the variable time step logic and provide an overview of the system architecture. Finally, we demonstrate model behavior and sensitivity to variable time steps through application to a large boreal forest landscape. We simulated pre-industrial forest fire regimes in order to establish base-line conditions for future management. Differing model time steps substantially altered our estimates of pre-industrial forest conditions. Where disturbance frequency is relatively high or successional processes long, the variable time steps may be a critical element for successful forest landscape modeling.
In this study, significant efforts have been devoted to optimizing energy consumption and driving range of an electric sport utility vehicle (ESUV). Vehicle energy flow tests were conducted at ...different temperatures, and integrated simulation models were built and validated. Subsequently, Natural Gradient Boosting (NGBoost) model was constructed based on extensive datasets obtained by parallel simulation framework, and many-objective optimizations of ESUV design parameters were performed. The results show that energy consumption per 100 km under high and low temperatures increases by 19.3 % and 34.9 % compared to room temperature, while effective work of half-axis decreases by 12.9 % and 28 %, suggesting extreme environmental temperature significantly affects ESUV performance. Mean square errors (MSEs) of NGBoost model predictions are less than 0.12, indicating its reliable predictive capability for unknown data. Many-Objective Random Walk Grey Wolf Optimizer (MORW-GWO) algorithm achieves optimal or suboptimal results on 10 test problems, fully demonstrating its efficient convergence and excellent robustness. Battery recovered energy, effective work of half-axis and electricity consumption per 100 km of final optimization scheme are increased by 20.2 %, 9.0 % and 13.0 %, with the largest overall percentage improvement of 17.3 %. These findings can provide data support and directional guidance for optimization designs and performance improvements of ESUVs.
Display omitted
•Integrated simulation model was built based on test data under multiple temperatures.•NGBoost model was constructed for precise prediction of ESUV overall performance.•MORW-GWO algorithm was proposed to perform efficient many-objective optimizations.•Final optimized scheme provided the largest total percentage improvement of 17.3 %.
The Overview, Design concepts and Details (ODD) protocol for describing Individual- and Agent-Based Models (ABMs) is now widely accepted and used to document such models in journal articles. As a ...standardized document for providing a consistent, logical and readable account of the structure and dynamics of ABMs, some research groups also find it useful as a workflow for model design. Even so, there are still limitations to ODD that obstruct its more widespread adoption. Such limitations are discussed and addressed in this paper: the limited availability of guidance on how to use ODD; the length of ODD documents; limitations of ODD for highly complex models; lack of sufficient details of many ODDs to enable reimplementation without access to the model code; and the lack of provision for sections in the document structure covering model design rationale, the model's underlying narrative, and the means by which the model's fitness for purpose is evaluated. We document the steps we have taken to provide better guidance on: structuring complex ODDs and an ODD summary for inclusion in a journal article (with full details in supplementary material; Table 1); using ODD to point readers to relevant sections of the model code; update the document structure to include sections on model rationale and evaluation. We also further advocate the need for standard descriptions of simulation experiments and argue that ODD can in principle be used for any type of simulation model. Thereby ODD would provide a lingua franca for simulation modelling.
An increasing number of countries are investigating options to stop the spread of the emerging zoonotic infection Salmonella (S.) Dublin, which mainly spreads among bovines and with cattle manure. ...Detailed surveillance and cattle movement data from an 11-year period in Denmark provided an opportunity to gain new knowledge for mitigation options through a combined social network and simulation modeling approach. The analysis revealed similar network trends for non-infected and infected cattle farms despite stringent cattle movement restrictions imposed on infected farms in the national control program. The strongest predictive factor for farms becoming infected was their cattle movement activities in the previous month, with twice the effect of local transmission. The simulation model indicated an endemic S. Dublin occurrence, with peaks in outbreak probabilities and sizes around observed cattle movement activities. Therefore, pre- and post-movement measures within a 1-mo time-window may help reduce S. Dublin spread.
To comply with the effluent standards and growing demands for safety and reliability, the operation of wastewater treatment processes (WWTPs) has been considered as a multiobjective control problem. ...In this article, a data-driven multiobjective predictive control (MOPC) method is developed to deal with the conflicting control objectives to improve the operation performance of WWTPs. The main contributions of MOPC are three folds: first, a multiobjective control strategy is developed in the design of MOPC. And an adaptive fuzzy neural network identifier, using the relevant process data, is designed to catch the nonlinear behaviors of WWTPs. Second, a transfer multiobjective optimization algorithm (TMOOA) is developed to obtain the optimal solutions of the conflicting control objectives. The major advantage of TMOOA is its low computational cost, which is realized by avoiding the computation of Pareto fronts. Third, the stability of MOPC has been given in detail. Meanwhile, the benefits and feasibility of MOPC are confirmed on the benchmark simulation model no. 2. The results further demonstrate the effectiveness of the proposed control method.
Theory and experiments suggest that rhizodeposition can accelerate N-cycling by stimulating microbial decomposition of soil organic matter (SOM). However, there are remarkably few experimental ...demonstrations on the degree to which variations in root exudation alter rhizosphere N dynamics in the field. We conducted a series of in situ substrate addition experiments and a modeling exercise to investigate how exudate mimics and enzyme solutions (at varying concentrations) influence rhizosphere SOM and N dynamics in a loblolly pine (Pinus taeda) plantation (Duke Forest). Exudates were added semi-continuously to unfertilized and fertilized soils in summer and fall; enzymes were added during the following summer. Exudate additions enhanced the microbial biomass specific activities of enzymes that degrade fast-cycling N pools (i.e., amino acids and amino sugars), and increased microbial allocation to N-degrading compounds. More, such effects occurred at low exudate concentrations in unfertilized soil and at higher concentrations in fertilized soil. Direct additions of a subset of enzymes (amino sugar- and cellulose-degrading) to soils increased net N mineralization rates, but additions of enzymes that cleave slow-cycling SOM did not. We conclude that exudates can stimulate microbes to decompose labile SOM and release N without concomitant changes in microbial biomass, yet the investment of plants to trigger this effect may be greater in N-rich soils.
•Evidence for a mechanistic link between root exudation and accelerated N cycling.•Exudate additions enhanced fast-cycling N degrading enzyme activities.•Additions of fast-cycling N degrading enzymes increased net N mineralization.•Much of the extra N is likely derived from amino acids and amino sugars.•Investment of plants to trigger SOM decomposition is much higher in N-rich soils.
PDF
