Qiaoxue Dong

Crop Model-Based Greenhouse Optimal Control System: Survey and Perspectives

A survey is presented of the developments in scientific literature on the greenhouse optimal control. The related problems to optimal control were discussed, and the schematic diagram of optimal control system, combined crop models and optimization algorithm were covered focusing on issues such as: model simplification and validation, definition of objective function, input or output constraints and dynamic optimization, and especially structure-function Greenlab model was made s a first exploration for the optimal control application. Not only the above research issues were listed in the paper, the perspectives and the solutions are presented as well. It is pointed out that only the crop growth model is integrated into the greenhouse climate optimal control, the best economical result and energy-saving can be warranted.

Beta Function Law to Model the Dynamics of Fruit’s Growth Rate in Tomato: Parameter Estimation and Evaluation

The calculation of fruit growth rate (FGR) is the main part of fruit-bearing crop growth models. In this paper, greenhouse tomato was used as a research material. The purpose of this study is to better understand the regulation of single fruit growth response to environmental or genetic factors. A FGR model of tomato fruit was described based on Beta function law because it has flexible ability to generate different curve shape when adjusting its parameters. A field experiments with 4 planting densities in 2012 spring was carried out in China, using the cultivar Weichi. The parameters of Beta-law FGR model were estimated with data from the fruits in the first truss by using the optimization algorithm Nelder-Mead The results showed that the optimization procedure described in this paper found best fitted and robust parameters, which implied that those parameters are cultivar specific, and little environmental dependence. The validation against the data from the second truss and third truss with variations in planting density was found to be acceptable (R2 = 0.9117). This modeling methodology and software program have the potential to become a powerful tool for optimization of ideotype design.

Interactive Pruning Simulation of Apple Tree

Pruning treatment is one of the important management practices of perennial fruit tree cultivation. Combining fruit tree growth theory with mathematics model and software development is an effective way in agricultural research. Virtual apple tree is built as a case to study pruning treatment in this paper. First, architectural development of apple tree was analyzed and stored in xml file. Then, the simulation software of apple tree pruning is build based on the Qt framework and OpenGL graphics library. The interactive pruning and automatic pruning with setting conditions are realized in the software. Reaction laws of apple tree pruning are extracted from the analysis on the experiment data. Stochastic 3D apple tree architectures after being pruned also can be simulated. Result indicates that simulation is efficient, accurate and timely judgment of pruning reaction is possible. This work is the foundation of future research, which will simulate the apple tree development of architecture and biomass after pruning treatment over time.

Utilizing Model to Optimize Crop Plant Density: A Case Study on Tomato

Based on the functional-structural plant model GreenLab, a common plant category tomato was selected as a test case in order to analyze the impact of plant density on the yield. A yield optimization model was set up based on minimum ripe fruit weight constraints, fruit weight serve as the objective function for the bound-constrained optimization problem. Particle Swarm Optimization (PSO) algorithm was applied for maximizing the crop production, which will provide a theoretical reference for agronomy measures based on plant spacing.

Planting-Density Optimization Study Fortomato Fruit Set and Yield Based Onfunctional-Structural Model Greenlab

Quantification of tomatos fruit-sets depends on the level of competition for assimilate in different environment, and this paper presented some results of fruit yield and quality (fruit size) in response to environment (mainly respect to and planting-density and light). Some experiments had been carried out to find the relationship between growth rules of tomato and plant densities A structural-functional model GREENLAB has been developed to simulate it. The results show that increasing plant density results in an increment of biomass production on a ground area but in a reduction of single plant fresh weight. To find rules between organ sink and source relationship, calibrations Environmental conditions were introduced into the model checking the influence on Q/D over plant growth period and fruit set ratio. It is found that changing the Q/D ratio in some critical periods can be used to optimize fruit set and yield of greenhouse tomato.

Light Simulation Inside Tomato Canopy Based on a Functional-structural Growth Model

This paper present how the light transfer and interception inside the canopy was computed by combining a tomato dynamic growth model. The tomato functional structural growth model was applied to produce the topology and geometry of individual plant, and through transformation, the canopy could be composed of multi-individual plants. In this simulation system, a radioactive transfer model named hierarchical instantiation for radiosity, was coupled effectively into this tomato growth model to compute the repartition of light energy throughout the canopy, so the key interface technology when integration were explained in the paper. Finally, the visualization results were presented for the light simulation inside canopy.

Study on Greenhouse Temperature Variable Universal Adaptive Fuzzy Control

Abstract: Basic fuzzy controller (BFC) has been successfully adopted to control greenhouse environment temperature. Variable universal adaptive fuzzy controller (VUAFC) which can contracts or expands the universal of the fuzzy variables of the BFC by the value of response error has been developed to get better control performance. By analyzing the result of experiments, VUAFC improved the performance of the fuzzy controller greatly.