Optimal water allocation and scheduling for irrigation using ant colony algorithms

In most regions of the world, irrigation is vital for food production. However, under increased water demands due to population growth, economic development, and climate change in recent decades, there is likely to be a significant reduction in the amount of water available for irrigation. Therefore, it is imperative to make the best use of water that is available for irrigation. This applies to: 1) the optimal allocation of land and water resources for irrigation management to achieve maximum net return, subject to constraints on area and water allocations at the district or regional scale; and 2) the optimal irrigation scheduling of available water, as well as fertilizer, in order to maximise net return at the farm scale. In order to rigorously address these problems, metaheuristic optimization algorithms have been used extensively due to their abilities in terms of finding globally optimal or near-globally optimal solutions and relative ease of linkage with complex simulation models. However, the application of these algorithms to real-world problems has been challenging due to the generally large size of the search space and the computational effort associated with realistic long-term simulation of crop growth and associated soil-water processes. In this thesis, general simulation-optimization frameworks for optimal irrigation management (including optimal crop and water allocation, and optimal irrigation water and fertilizer application scheduling) have been developed in order to make the application of metaheuristic optimization methods to the above problems more computationally efficient. As part of this approach the problems are represented in the form of decision graphs which are solved using ant colony optimization (ACO) as the optimization engine. The frameworks enable dynamic reduction of the size of the search space by using dynamic decision variable option (DDVO) adjustment during solution construction. This also ensures only feasible solutions are obtained as part of the stepwise solution generation process. In addition, the computational efficiency of the ACO algorithms within the framework for optimal crop and water allocation has been increased by biasing the options at each node in the decision-tree graph based on domain knowledge (represented by a visibility factor, VF). Furthermore, the framework for optimal irrigation scheduling was linked with a process-based crop growth model to enable optimal or near-optimal irrigation water and fertilizer application schedules to be identified. This thesis is arranged as a series of three publications that present the main research contributions. The first paper introduces a generic simulation-optimization framework for optimal crop and water allocation at the regional or district scale using decision-tree graphs, ACO and the search space reduction technique based on dynamically adjusting decision variable options during stepwise solution construction. The performance of this technique in terms of finding feasible solutions, solution quality, computational efficiency and convergence speed was compared with that of linear programming (LP) and a “standard” ACO approach using static decision variable options (SDVO) on a benchmark case study from the literature. The second paper extends the ACO formulation for optimal crop selection and irrigation water allocation in the first paper by incorporating domain knowledge through VFs to bias the search towards selecting crops that maximize net returns and water allocations that result in the largest net return for the selected crop, given a fixed total volume of water. This improvement enables locally optimal solutions related to the factors (i.e., crops and water) affecting net return to be identified, and enables promising regions of the search space to be explored. The benefits of this improved formulation were tested on the benchmark case study used in the first paper and a real-world case study based on an irrigation district located in Loxton, South Australia near the River Murray. In the final paper, the formulation for detailed optimal irrigation water and fertilizer application scheduling at the farm scale is introduced and applied to a case study considering corn production under center pivot irrigation in Colorado, USA. The Root Zone Water Quality Model 2 (RZWQM2) was used for this case study to simulate the detailed impacts of irrigation water and fertilizer application scheduling on crop growth at a fixed time step. The utility of the proposed framework was demonstrated in terms of finding better net returns while using less fertilizer and similar amounts of water, or similar net returns while using less water and fertilizer, compared with the Microsoft Excel spreadsheet-based Colorado Irrigation Scheduler (CIS) tool for annual crops.Thesis (Ph.D.) (Research by Publication) -- University of Adelaide, School of Civil, Environmental and Mining Engineering, 2016

Enhancing Water Supply Resilience in a Tropical Island via a Socio-Hydrological Approach: A Case Study in Con Dao Island, Vietnam

Socio-hydrological approaches are gaining momentum due to the importance of understanding the dynamics and co-evolution of water and human systems. Various socio-hydrological approaches have been developed to improve the adaptive capacity of local people to deal with water-related issues. In this study, a social-hydrological approach was developed to enhance the water supply resilience in Con Dao Island, Vietnam. We used a water-balance model, involving the Water Evaluation and Planning (WEAP) tool, to conduct a scenario-based evaluation of water demands. In doing so, we assessed the impacts of socio-economic development, such as population growth and climate change, on increasing water demand. The modelling results showed that the existing reservoirs—the main sources to recharge the groundwater (accounting for 56.92% in 2018 and 65.59% in 2030)—play a critical role in enhancing water supply resilience in the island, particularly during the dry season. In addition, future water shortages can be solved by investment in water supply infrastructures in combination with the use of alternative water sources, such as rainwater and desalinated seawater. The findings further indicate that while the local actors have a high awareness of the role of natural resources, they seem to neglect climate change. To meet the future water demands, we argue that upgrading and constructing new reservoirs, mobilizing resources for freshwater alternatives and investing in water supply facilities are among the most suitable roadmaps for the island. In addition, strengthening adaptive capacity, raising awareness and building professional capacity for both local people and officials are strongly recommended. The research concludes with a roadmap that envisages the integration of social capacity to address the complex interaction and co-evolution of the human–water system to foster water-supply resilience in the study area

Observation and Simulation of Wind Speed and Wind Power Density over Bac Lieu Region

In this study, the WRF (Weather Research and Forecasting) model was used to simulate and investigate diurnal and annual variations of wind speed and wind power density over Southern Vietnam at 2‐km horizontal resolution for two years (2016 and 2017). The model initial and boundary conditions are from the National Centers for Environmental Prediction (NCEP) Final Analyses (FNL). Observation data for two years at 20 m height at Bac Lieu station were used for model bias correction and investigating diurnal and annual variation of wind speeds. The results show that the WRF model overestimates wind speeds. After bias correction, the model reasonably well simulates wind speeds over the research area. Wind speed and wind power density show much higher values at levels of 50–200 m above ground levels than near ground (20 m) level and significantly higher near the coastal regions than inland. Wind speed has significant annual and diurnal cycles. Both annual and diurnal cycles of wind speeds were well simulated by the model. Wind speed is much stronger during daytime than at nighttime. Low-level wind speed reaches the maximum at about 14 LT to 15 LT when the vertical momentum mixing is highly active. Wind speeds over the eastern coastal region of Southern Vietnam are much stronger in winter than in summer due to two main reasons, including (1) stronger large-scale wind speed in winter than in summer and (2) funnel effect creating a local maximum wind speed over the nearshore ocean which then transports high-momentum air inland in winter

A review of mathematical methods for flexible robot dynamics modeling and simulation

In recent decades, lots of robots are designed and produced all over the world because of their important applications. Nowadays, using the robot is more and more popular in many different fields. In practice, the modeling and control of most of the robots are performed with an important assumption that all links of a robot are rigid bodies. This is to simplify the modeling, analysis, and control for a robot. The elastic deformation of a link always exists during a robot’s operation. This elastic deformation of a flexible robot has significant effects on several characterizations and specifications of the robot such as the robot strength, the accuracy of the robot motion, the robot control, etc. In the literature, there have been many studies addressing the dynamics modeling and control of flexible robots. This paper presents an overview of the mathematical methods which have been used for the kinematic and dynamic modeling of the flexible manipulators

A Review of Mathematical Methods for Flexible Robot Dynamics Modeling and Simulation

In recent decades, lots of robots are designed and produced all over the world because of their important applications. Nowadays, using the robot is more and more popular in many different fields. In practice, the modeling and control of most of the robots are performed with an important assumption that all links of a robot are rigid bodies. This is to simplify the modeling, analysis, and control for a robot. The elastic deformation of a link always exists during a robot’s operation. This elastic deformation of a flexible robot has significant effects on several characterizations and specifications of the robot such as the robot strength, the accuracy of the robot motion, the robot control, etc. In the literature, there have been many studies addressing the dynamics modeling and control of flexible robots. This paper presents an overview of the mathematical methods which have been used for the kinematic and dynamic modeling of the flexible manipulators

Ho chicken breed: Morpho-biometric characteristics and Economic efficiency of production

peer reviewedIn order to evaluate the economic efficiency and production status of Ho chicken, this survey was carried out on 34 households raising Ho chickens in Thuan Thanh district, Bac Ninh province, from December 2012 to April 2013. Morpho-biometric characteristics were measured on 181 individuals (46 cocks and 135 hens) according to FAO standards. The results show that Ho chicken herd size is very limited, with 30.78 chickens per household. Average age at the first laying is rather late (7.42 months) with 11.97 eggs in a laying cycle and 76.32% of hatchability rate. These numbers are low because Ho chickens are heavy and clumsy, and therefore could easily step on and break their eggs. The body weight of a cock is 3.79 kg at 9 months while the hen weight is 2.63kg at 12 months. The body length, neck length, back length, thigh length of cock are significantly higher than those of hens (P<0.05). Production of these chickens does not require much initial investment costs. In these costs, buy breed and chicken housing are the most important in the fixed costs. The average annual expense to operate Ho chicken production reaches 12.16 million VND (565.58 USD) while the average annual revenue is 30.85 million VND (1443 USD)

A Multidisciplinary approach to treat massive recurrent hematochezia from a jejunal Dieulafoy lesion: A case report

Jejunal Dieulafoy lesion (DL) is an exceedingly rare, life-threatening cause of gastrointestinal bleeding. Due to its rarity, intermittent bleeding symptoms that often necessitate prompt clinical intervention, variability in detection and treatment methods, and the risk of rebleeding, this condition frequently presents a diagnostic and therapeutic conundrum. We report a case of severe, intermittent, recurrent hematochezia due to a jejunal DL that was difficult to localize. In this case, the metallic coils used as a radiopaque marker allowed surgeons to accurately identify the bleeding site during intraoperative enteroscopy and successfully manage the lesion with minimally invasive laparoscopic surgery