Simulation of site-specific irrigation control strategies with sparse input data

Crop and irrigation water use efficiencies may be improved by managing irrigation application timing and volumes using physical and agronomic principles. However, the crop water requirement may be spatially variable due to different soil properties and genetic variations in the crop across the field. Adaptive control strategies can be used to locally control water applications in response to in-field temporal and spatial variability with the aim of maximising both crop development and water use efficiency. A simulation framework ‘VARIwise’ has been created to aid the development, evaluation and management of spatially and temporally varied adaptive irrigation control strategies (McCarthy et al., 2010). VARIwise enables alternative control strategies to be simulated with different crop and environmental conditions and at a range of spatial resolutions. An iterative learning controller and model predictive controller have been implemented in VARIwise to improve the irrigation of cotton. The iterative learning control strategy involves using the soil moisture response to the previous irrigation volume to adjust the applied irrigation volume applied at the next irrigation event. For field implementation this controller has low data requirements as only soil moisture data is required after each irrigation event. In contrast, a model predictive controller has high data requirements as measured soil and plant data are required at a high spatial resolution in a field implementation. Model predictive control involves using a calibrated model to determine the irrigation application and/or timing which results in the highest predicted yield or water use efficiency. The implementation of these strategies is described and a case study is presented to demonstrate the operation of the strategies with various levels of data availability. It is concluded that in situations of sparse data, the iterative learning controller performs significantly better than a model predictive controller

Air pollution and livestock production

The air in a livestock farming environment contains high concentrations of dust particles and gaseous pollutants. The total inhalable dust can enter the nose and mouth during normal breathing and the thoracic dust can reach into the lungs. However, it is the respirable dust particles that can penetrate further into the gas-exchange region, making it the most hazardous dust component. Prolonged exposure to high concentrations of dust particles can lead to respiratory health issues for both livestock and farming staff. Ammonia, an example of a gaseous pollutant, is derived from the decomposition of nitrous compounds. Increased exposure to ammonia may also have an effect on the health of humans and livestock. There are a number of technologies available to ensure exposure to these pollutants is minimised. Through proactive means, (the optimal design and management of livestock buildings) air quality can be improved to reduce the likelihood of risks associated with sub-optimal air quality. Once air problems have taken hold, other reduction methods need to be applied utilising a more reactive approach. A key requirement for the control of concentration and exposure of airborne pollutants to an acceptable level is to be able to conduct real-time measurements of these pollutants. This paper provides a review of airborne pollution including methods to both measure and control the concentration of pollutants in livestock buildings

Development of a naturally-ventilated solar energy-assisted maize seed store.

Masters Degree. College of Agriculture, Engineering and Science, University of KwaZulu-Natal, Pietermaritzburg, 2018.The seed industry continues to face losses during seed storage, especially in Africa. Moreover, there is high loss of seed viability during storage, mainly due to the poor ventilation in seed storage structures, which results in the development of storage fungi. In this study, the main objectives were to construct, to evaluate the solar energy assisted maize seed store. A 22-m3 room was converted to a seed storage room by retrofitting a chimney on its wall and a solar collector on its roof. Different chimney sizes were investigated in order to identify which size would be best for the construction of a naturally-ventilated seed storage room. The chimney sizes that were used included those with a diameter and a height of 200 mm x 3600 mm, 200 mm x 4800 mm, 300 mm x 3600 m and 300 mm x 4800 mm. The parameters, air velocity in the chimney duct, as well as the air temperature and relative humidity at the inlet, centre and outlet of the storage room, were recorded during the seed storage period. A naturally- ventilated seed storage room was developed based on the results obtained. A naturally-ventilated seed storage room was then evaluated in terms of its effectiveness to preserve the quality of the stored maize seeds. To compare the performance of the modified storage room, a room with similar storage capacity, but without the retrofitted components, was used as a control. Maize seeds were stored in each storage room for the duration of three months. Samples were taken every two weeks for germination, moisture content and seed vigour analyses. Both the diameter and height of the chimney were found to have a significant (P≤0.05) influence on the air ventilation rate inside the storage room. A seed storage was therefore developed using a 300 mm x 4.8 m chimney size, which performed better than the other chimney sizes that were explored in this study. The relative humidity in the control storage room was significantly (P≤0.05) higher (60.6 ± 5.87%) than the relative humidity in the modified storage room (40.1 ± 3.21%). The moisture content obtained in the control room was significantly (P≤0.05) higher (13.3%) than the moisture content obtained in the modified storage room (12.6%). The initial germination was 99%. The seed germination percentage obtained after three months of storage in the modified storage room was significantly higher (P≤0.05) (98.5 ± 0.85%) than the germinations percentage obtained in the control storage (96.8 ± 1.49%). The seed vigour obtained in the modified storage was significantly higher (P≤0.05) than the seed vigour obtained in the control room. Thus, a naturally-ventilated seed storage room was tested and was found to preserve the quality of the seeds over the duration of storage

Energy Efficient Window Development

The paper investigates the development of energy efficient windows in the past 30 years. The focus is on the development and interlinkages among technology, actors´ interaction and market diffusion in a broader policy context. The paper shows that in singular development cycles, different factors and the interfaces among these factors influenced the improvement and penetration of energy efficient window technologies. Such factors includes a) surrounding factors, such as climate characteristics, oil crisis and international concerns and strategies, b) policy instruments, like building codes and technology procurement programs, as well as c) industry initiatives, including niche market strategies

Development of probabilistic models for quantitative pathway analysis of plant pest introduction for the EU territory

This report demonstrates a probabilistic quantitative pathway analysis model that can be used in risk assessment for plant pest introduction into EU territory on a range of edible commodities (apples, oranges, stone fruits and wheat). Two types of model were developed: a general commodity model that simulates distribution of an imported infested/infected commodity to and within the EU from source countries by month; and a consignment model that simulates the movement and distribution of individual consignments from source countries to destinations in the EU. The general pathway model has two modules. Module 1 is a trade pathway model, with a Eurostat database of five years of monthly trade volumes for each specific commodity into the EU28 from all source countries and territories. Infestation levels based on interception records, commercial quality standards or other information determine volume of infested commodity entering and transhipped within the EU. Module 2 allocates commodity volumes to processing, retail use and waste streams and overlays the distribution onto EU NUTS2 regions based on population densities and processing unit locations. Transfer potential to domestic host crops is a function of distribution of imported infested product and area of domestic production in NUTS2 regions, pest dispersal potential, and phenology of susceptibility in domestic crops. The consignment model covers the several routes on supply chains for processing and retail use. The output of the general pathway model is a distribution of estimated volumes of infested produce by NUTS2 region across the EU28, by month or annually; this is then related to the accessible susceptible domestic crop. Risk is expressed as a potential volume of infested fruit in potential contact with an area of susceptible domestic host crop. The output of the consignment model is a volume of infested produce retained at each stage along the specific consignment trade chain

Assessment of CO2 Health Risk in Indoor Air Following a Leakage from a Geological Storage: Results from the First Representative Scale Experiment

If a leakage of CO2 out of a geological reservoir were to happen and to reach the vadose zone below a building, CO2 could migrate through the vadose and the building's slab and accumulate in the building, leading to possible acute risk for the inhabitants. A representative-scale experiment, including a prototype for a building, was developed to better understand and quantify this possible risk. It brought fruitful directions for further modeling work, since unexplained CO2 peaks were observed in the prototype. Numerical simulations were carried out to address the variability of CO2 concentrations considering the influence of soil and building properties as well as meteorological conditions, with promising results for risk analysis

Autophage engines: towards a throttleable solid motor

This paper describes the instrumented test firing of a rocket that seeks to combine the throttleability of a liquid-fueled engine with the simplicity of a solid motor. The concept is that a differentiated fuel and oxidizer rod is forced into a vaporization unit where its constituents transition into separate propellant gases, which are then mixed in a combustion chamber. The vaporization unit is heated by the combustion, and the throttle setting is adjusted by changing the force used to drive the solid propellant rod into the vaporizer, which naturally influences the propellant feed rate. In experiments using a solid propellant rod consisting of polypropylene fuel and a 1∶1.5 mixture of NH4ClO4 and NH4NO3 oxidizer, operations have been sustained for around 60 s. During testing, using propellant feed forces of between 250 and 900 N, propellant feed rates of between 100 and 300 mm/min have been achieved, which are in turn correlated to chamber pressures of between approximately 300 and 700 kPa. These correlated cycles of control input (the feed force), throttle response (the propellant feed rate), and implied thrust (the chamber pressure) demonstrate, for the first time, a simple solid rocket that can be throttled in real time

Economic and environmental analysis of energy efficiency measures in agriculture. Case Studies and trade offs.

This report is the result of the collaboration of the partners of the AGREE work-package “Economic and environmental analysis”, which is based on case study analyses of the partners in seven countries of the EU. The case studies show economic and environmental trade-offs in the different regions in the EU, for which each partner is responsible. Nevertheless prior to the reporting of the case studies an intensive discussion on a common methodological approach has been accomplished and applied to the case studies. The case studies show a wide range of different perspectives of energy efficiency in agriculture, but they are all based on the common methodology presented in Chapter 3. In Chapter 4, the case studies are presented, with authors indicated at the beginning of each section. Each section of Chapter 4 ends with a synthesis analysis of the results from the different case studies. Chapter 5 summarizes and concludes the report by highlighting the major findings of the analyses. The report builds upon the “State of the Art in Energy Efficiency in Europe” published separately by the AGREE consortium (Gołaszewski et al. 2012), which shows the status quo of energy use and possible energy efficiency measures in agriculture across different production systems and regions in Europe. This report presents an economic and environmental analysis based on in-depth case studies which show the potential for, and constraints on, energy efficiency measures in agriculture with respect to the specific environments in Europe

Rural structures in the tropics: Design and development

There is a growing awareness of the need for better rural structures and services in many developing countries. Here the FAO presents an up-to-date, comprehensive text focusing on structures for small- to medium-scale farms and, to some extent, village-scale agricultural infrastructure. The book will help to improve teaching on the subject of rural buildings in the tropics and will assist professionals engaged in providing technical advice. Importantly, it also provides guidance in the context of disaster recovery and rehabilitation, for rebuilding the sound rural structures and related services that are key to development and economic sustainability