Biosystems engineering Research Papers - Academia.edu (original) (raw)

The objective of this work was to evaluate the effect of moisture content variation on reduction of superficial area, volume and equivalent sphere diameter of coffee berries. Four varieties of Coffea arabica (cv Catua! ı ı Vermelho,... more

The objective of this work was to evaluate the effect of moisture content variation on reduction of superficial area, volume and equivalent sphere diameter of coffee berries. Four varieties of Coffea arabica (cv Catua! ı ı Vermelho, Catua! ı ı Amarelo, Mundo Novo and Catimor) and one variety of Coffea canephora (cv Conilon) were used. From the results obtained, it was concluded that moisture content in the coffee berries affects its physical properties causing significant decrease of the superficial area, volume and diameter of the equivalent sphere during a drying process. The varieties of coffee had different shrinkage behaviour. The Conilon coffee had the highest level of berry shrinkage, the volume decreased 35% during the drying process from 1Á38 to 0Á12 dry basis (d.b.) berry moisture content. The shrinkage behaviour during the drying process was well explained by a polynomial model with coefficient of determination greater than 90%.

Micronisation (infrared heat treatment) following tempering (conditioning) is an effective means of reducing cooking time in grain legumes such as lentils. However, the physical, physico-chemical and chemical changes that bring about this... more

Micronisation (infrared heat treatment) following tempering (conditioning) is an effective means of reducing cooking time in grain legumes such as lentils. However, the physical, physico-chemical and chemical changes that bring about this desirable change in the lentils have not been extensively investigated. The objective of this study was to investigate the physical changes occurring in lentils as a result of micronisation at different moisture contents. Lentils were tempered to a range of moisture contents (17-45%) and micronised under an electric microniser to return them to their initial moisture content (13%). Control samples were tempered to the same moisture contents but were air-dried (at 40 1C). Changes in the density and apparent elastic modulus (of a collection of grains) of the processed lentils were measured, as was the diffusion coefficient of moisture into them. Porosity of the micronised lentils increased with increasing tempering moisture, up to approximately 25%, arising from void creation induced by evaporation of moisture. However, porosity decreased at higher tempering moisture contents, presumably due to filling of voids by amylose from partially gelatinised starch granules. Changes in the porosity of air-dried lentils were slight. Apparent elastic modulus of the micronised lentils was essentially unaffected by tempering conditions. The rewetting coefficient of the micronised lentils was significantly greater than that of air-dried lentils, and the difference increased as tempering moisture content was increased. Diffusion coefficients of moisture within the lentils were strongly dependent on tempering moisture content, increasing as tempering moisture increased. The results indicate that rate of hydration of the lentils (a factor in cooking time reduction) depends on the physico-chemical changes brought about by heat and moisture during micronisation as well as on the increase in porosity.

Researchers have traditionally predicted animal responses by means of statistical models. This study was conducted to evaluate modelling techniques. One hundred and twenty-eight feedlot heifers were observed during a 2-month period during... more

Researchers have traditionally predicted animal responses by means of statistical models. This study was conducted to evaluate modelling techniques. One hundred and twenty-eight feedlot heifers were observed during a 2-month period during the summer of 2002. Respiration rate and surface temperature were taken on a random sample of 40 animals twice a day. Five different models (two statistical models, two fuzzy inference systems, and one neural network) were developed using 70% of this data, and then tested using the remaining 30%. Results showed that the neural network described the most variation in test data (68%), followed by the data-dependent fuzzy model (Sugeno type) (66%), regression models (59 and 62%), while the data-free fuzzy model (Mamdami type) described only 27%. While the neural-network model may be a slightly better approach, the researcher may learn more about responses using a fuzzy inference system approach. For all models tested, respiration rate is over-predicted at low stress conditions and under-predicted at high stress conditions. This suggests that all models are lacking a key piece of input data, possibly the accumulative effects of prior weather conditions, to make an accurate prediction.

Ammonia emissions from mink houses were measured over two seasons for growing kits in a two-row opensided building with slurry gutters (385 mm wide). In the first season, a layer of sand was placed below the cages, and in the last season... more

Ammonia emissions from mink houses were measured over two seasons for growing kits in a two-row opensided building with slurry gutters (385 mm wide). In the first season, a layer of sand was placed below the cages, and in the last season a layer of chopped barley straw on sand, to serve as a collector for urine and faeces dropped outside the gutter. When the slurry was removed weekly in the houses with slurry gutter and sand layer, the ammonia emission was 0Á59 g [N] per animal per 24 h at 68C and 1Á15 g [N] per animal per 24 h at 168C. By covering the ground area below the cages with a layer of chopped barley straw, renewed weekly, the nitrogen loss increased with the time since the latest renewal of the straw. One week after renewal of straw and removal of slurry, the emission amounted to 0Á70 g [N] per animal per 24 h at 68C and 1Á44 g [N] per animal per 24 h at 168C. Nine-week nitrogen balance measurements were carried out in three sections over the second season. When a layer of chopped barley straw on the ground area was renewed once a week, about 45% of the nitrogen in the consumed feed was collected in the slurry gutter by emptying the gutter twice a week. About 19% was collected in straw beneath the cages, about 5% was deposited in the carcass, about 20% evaporated, and the rest, about 11%, was assumed to be collected in the sand layer below the cages.#

The design of the supply chain, and in particular of the distribution phase, for fresh-food products, such as fresh and fresh-cut produce, fruit or meat, cannot be achieved without considering the perishable nature and the variability of... more

The design of the supply chain, and in particular of the distribution phase, for fresh-food products, such as fresh and fresh-cut produce, fruit or meat, cannot be achieved without considering the perishable nature and the variability of the products entering the chain.

This work discusses application of acoustically-derived index of disintegration for characterization of pulsed electric field (PEF)-treated whole apples in aqueous media. It was demonstrated that PEF efficiency was dependent on the... more

This work discusses application of acoustically-derived index of disintegration for characterization of pulsed electric field (PEF)-treated whole apples in aqueous media. It was demonstrated that PEF efficiency was dependent on the conductivity of the aqueous media and orientation of the apple with respect to the external field. Electrical treatment also stimulated transient changes after PEF application in acoustic disintegration index (Z a ).

Between 1997 and 1999 a comprehensive survey of airborne pollutant concentrations within, and emissions from, 160 Australian piggery buildings was undertaken. The primary aim of the study was to model the concentrations and emissions of... more

Between 1997 and 1999 a comprehensive survey of airborne pollutant concentrations within, and emissions from, 160 Australian piggery buildings was undertaken. The primary aim of the study was to model the concentrations and emissions of different airborne pollutants and thus identify potential reduction techniques. The main factors identified as significantly influencing airborne pollutant concentrations were building type, pen hygiene, pig flow management, seasons, building volume, ventilation airflow rate, air temperature, relative humidity, and farm size (as expressed by number of sows on site). These effects were included in comprehensive statistical models to explain the variation in measured concentrations and emission rates. The models developed were validated and fine-tuned using the ''leave-one-out'' cross-validation technique. This article details the validation technique used that was aimed to maximise the value of available experimental data and further improves the practicality of the models developed. The main result of the study was the development of an improved model. The study results, and the resulting prediction models, should help improve air quality in piggery buildings by providing decision makers with an awareness of the environmental conditions inside and outside of piggery buildings. In turn, that should lead to improvements in the health and welfare of pigs and piggery staff and the sustainability of the piggery operations. (T.M. Banhazi).

Regulatory instruments at the national level to ensure high quality are crucial to achieve and maintain a regional hub of higher education in Malta. While The Malta Qualifications Council and the National Commission for Higher Education... more

Regulatory instruments at the national level to ensure high quality are crucial to achieve and maintain a regional hub of higher education in Malta. While The Malta Qualifications Council and the National Commission for Higher Education are established and operational, the legal framework to set up a quality assurance agency and a quality assurance and licensing framework is in place, but the legislations is still awaiting approval. The University of Malta has set up internal quality assurance structures, The Programme Validation Committee monitors, reviews and recommends programmes for approval by Senate, The formation of the INSTITUTE OF EARTH SYSTEMS will facilitate the means through which a Bio Systems Engineering course could be offered, Furthermore the recent establishment of a Maltese Chamber of Agrologists could in theory eventually take up the role to grant professional accreditation,

In general, meteorological parameters such as temperature, rain and global radiation are important for agricultural systems. Anticipating on future conditions is most often needed in these systems. Weather forecasts then become of... more

In general, meteorological parameters such as temperature, rain and global radiation are important for agricultural systems. Anticipating on future conditions is most often needed in these systems. Weather forecasts then become of substantial importance. As weather forecasts are subject to uncertainties, there is a need in minimising the uncertainties. In this paper, a framework is presented in which local weather forecasts are updated using local measurements. Kalman filtering is used for this purpose as assimilation technique. This method is compared and combined with diurnal bias correction. It is shown that the standard deviation of the forecast error can be reduced up to 6 h ahead for temperature, up to 31 h ahead for wind speed, and up to 3 h for global radiation using local measurements. Combining the method with diurnal bias correction leads to a further increase in performance in terms of both bias and standard deviation.

Small-scale roughness on bare agricultural soils determines very important properties such as infiltration, runoff or soil erosion. In this work, a method based on photogrammetric tools has been developed for the generation of automatic... more

Small-scale roughness on bare agricultural soils determines very important properties such as infiltration, runoff or soil erosion. In this work, a method based on photogrammetric tools has been developed for the generation of automatic digital elevation models (DEMs) in agricultural soils, and is compared with a method based on very accurate offthe-shelf three-dimensional (3D) laser scanners. High resolution and accurate DEMs are generated by both of these non-contact techniques on two agricultural field plots of about 0.2 m 2 : (i) untilled and smooth soil, and (ii) very cloddy tilled surface. Furthermore, classical microrelief parameters such as Random Roughness and Maximum Depressional Storage are computed from grid DEMs obtained by laser scanning and close-range photogrammetry. Both techniques are compared on agricultural soils in terms of data acquisition and analysis performance, resolution, accuracy, and capability of representing microrelief and for computing microrelief parameters. Both the techniques tested have proved able to generate, under ideal conditions, DEMs with high accuracy (standard deviations of the residuals were 0.121 mm and 0.467 mm for laser and photogrammetry, respectively) and resolution (about 0.4 mm for laser scanning and 1 mm for the photogrammetric method). It is also worth noting that soil DEMs can be generated by both methods in less than 2 h, using devices in field assays that are not too expensive. Laser scanning produces a far more detailed surface allowing it to reproduce smaller aggregates than the photogrammetric method. On the other hand, data acquisition is faster with digital photogrammetry. The worse performance with either method happens when they are used on a rougher type of soil. Regarding the proposed non-contact methodologies, field soil microrelief can be attained in a fast, accurate, and economic way. In addition, the microrelief parameters computed from agricultural soil grid DEMs by laser scanning and photogrammetry show quite similar values. (M.A. Aguilar).

The main source of ammonia and odour from most livestock buildings is the slurry pit. The ammonia emission rate is affected by the air exchange rate in the slurry pit. Reduction of air exchange between slurry pit and room air may reduce... more

The main source of ammonia and odour from most livestock buildings is the slurry pit. The ammonia emission rate is affected by the air exchange rate in the slurry pit. Reduction of air exchange between slurry pit and room air may reduce the emissions. The hypothesis that using an environmental deflector in the room and curtains in the slurry pit may affect air exchange rate between the slurry pit and the room air was validated. In the experiment, three position angles for the deflector and three arrangements of curtains were investigated in a two-dimensional ventilation chamber under isothermal conditions at two ventilation airflow rates. The airflow pattern, air velocity and turbulence intensity inside the chamber were also recorded. The results showed that the airflow patterns, air velocities and turbulence intensities in the room space near the slatted floor and in the headspace of the pit were influenced by changing deflector angles and curtain numbers. It was found that the lowest pit ventilation and the highest concentration in the headspace of the pit could be achieved by using a deflector's position angle of 45 at both of two airflow rates.

A monorail test system has been developed for studying the draught and power performance of narrow tillage tools operating at high speeds. The system is retrofitted to a small 10-m long linear soil bin, yet is capable of maintaining... more

A monorail test system has been developed for studying the draught and power performance of narrow tillage tools operating at high speeds. The system is retrofitted to a small 10-m long linear soil bin, yet is capable of maintaining target tool speeds of 0.5-10 m s À1 over 1 to 3 m distances. Rigid vertical tools with three different blade shapes, two operating depths and two widths were tested in a silty clay loam with soft and hard compaction levels to demonstrate system capabilities. Soil disturbance was measured using a profilemeter. Results showed increases in power, tool draught and soil pulverization with increases in speed, and measurable effects of tool geometry (shape, width, operating depth) and of soil strength on power and draught-speed relationships.

A prototype robot that moves on a monorail along the greenhouse for weed elimination between cucumber plants was designed and developed. The robot benefits from three arrays of ultrasonic sensors for weed detection and a PIC18 F4550-E/P... more

A prototype robot that moves on a monorail along the greenhouse for weed elimination between cucumber plants was designed and developed. The robot benefits from three arrays of ultrasonic sensors for weed detection and a PIC18 F4550-E/P microcontroller board for processing. The feedback from the sensors activates a robotic arm, which moves inside the rows of the cucumber plants for cutting the weeds using rotating blades. Several experiments were carried out inside a greenhouse to find the best combination of arm motor (AM) speed, blade rotation (BR) speed, and blade design. We assigned three BR speeds of 3500, 2500, and 1500 rpm, and two AM speed of 10 and 30 rpm to three blade designs of S-shape, triangular shape, and circular shape. Results indicated that different types of blades, different BR speed, and different AM speed had significant effects (P < 0.05) on the percentage of weeds cut (PWC); however, no significant interaction effects were observed. The comparison between ...

Agricultural fleet management is viewed as farmers' or machine contractors' decisionmaking concerning, for example, resource allocation, scheduling, routing, and real-time monitoring of vehicles and materials. In order to optimise this... more

Agricultural fleet management is viewed as farmers' or machine contractors' decisionmaking concerning, for example, resource allocation, scheduling, routing, and real-time monitoring of vehicles and materials. In order to optimise this management task, fleet management tools are used for decision support to improve scheduling, routing and other operational measures for a fleet of agricultural machines. Additionally, fleet management involves the process of supervising the use and maintenance of machines and the associated administrative functions including the coordination and dissemination of tasks and related information for solving the heterogeneous scheduling and routing problems. In order to analyse the complex situation of how to develop an effective Fleet Management System, a conceptual model was developed based on a participatory approach and subsequent system analysis. This involved identification of the scope of the system, identification of user requirements, conceptual modelling, identification of actors and decision processes, and information-needs modelling. A holistic view and scope of the system is presented together with the system constraints. The results build on extracted information from selected actors in the agricultural domain. The systems components are depicted and linked to the subsequent conceptual model of the overall system as an outline for a subsequent tool development and implementation.

A method was developed for the automatic endpoint determination of near-ambient barley drying in static deep beds, based on a correlation to infer grain moisture content of the top layer, using a continuous on-line measurement of relative... more

A method was developed for the automatic endpoint determination of near-ambient barley drying in static deep beds, based on a correlation to infer grain moisture content of the top layer, using a continuous on-line measurement of relative humidity and temperature of outlet air. The correlation was based on an equilibrium isotherm equation, modified by an empirical constant accounting for the non-equilibrium nature of drying. The modifying constant was fitted using results from nine laboratory experiments and validated in an on-farm drying experiment. Three desorption isotherm equations, specific for barley, were investigated: modified Henderson, Chung and Chung-Pfost equations. The correlation relationship developed from the Chung-Pfost isotherm equation and modified by the authors by the addition of a constant of 0.0213 kg kg À1 d.b. predicted moisture content in a 2-m-thick fixed-bed of malting barley cv. Annabell during the final phase of drying better than the other equations (in a climate that is the mixture of maritime and continental climates). The estimated accuracy of the proposed method is sufficient for practical applications with the post-harvest conservation of barley.

ABSTRACT During the ripening season, measurements were performed on 4 grape varieties (i.e. Cabernet Sauvignon, Merlot, Syrah and Carmenère). Spectral reflection measurements were performed on intact grapes using the Zeiss corona 45... more

ABSTRACT During the ripening season, measurements were performed on 4 grape varieties (i.e. Cabernet Sauvignon, Merlot, Syrah and Carmenère). Spectral reflection measurements were performed on intact grapes using the Zeiss corona 45 VIS–NIR spectrophotometer. Thereafter, the concentration of extractable anthocyanins at pH equal to 1.0 (pH10) and 3.2 (pH32), the concentration of polyphenols (IPT), the concentration of sugars (OH) and the density were determined from the samples. Partial least squares analysis showed that prediction of PH10 and PH32 was possible for Syrah. For this variety, PH10 and PH32 increased during the season and changes in the spectral properties of the grapes could be linked to these parameters. For all other varieties, the parameters PH10 and PH32 remained fairly constant over time and the results showed that prediction was not possible. The prediction of IPT was not possible for all varieties. The prediction of OH and density was achieved accurately for all varieties. An important region for the prediction of OH and density was detected around 700 nm, corresponding to the red colour. The prediction of sugar is consequently, at least partially, feasible due to the co-occurring colour change from green to blue/red.

Maximum reverse vehicle velocity a Vehicle acceleration ω Vehicle angular velocity d(i,j) RRT node distance metric between nodes (i) and (j) h(i,j) RRT node heading metric between nodes (i) and (j) m(i,j) RRT metric between nodes (i) and... more

Maximum reverse vehicle velocity a Vehicle acceleration ω Vehicle angular velocity d(i,j) RRT node distance metric between nodes (i) and (j) h(i,j) RRT node heading metric between nodes (i) and (j) m(i,j) RRT metric between nodes (i) and (j) g d RRT distance metric weight g h RRT heading metric weight g f RRT node failure rate metric weight n B-spline number of control point p B-spline curve degree m B-spline number of knots B-spline knot vector u B-spline parametric length k B-spline curvature K max Maximum B-spline Curvature u B-spline normalized length parameter N(u) B-spline basis function Px, Py B-spline control polygon coordinates c(u) B-spline curve x(u) B-spline curve x-coordinates y(u) B-spline curve y-coordinates L B-spline segment length α B-spline segment angle L min B-spline minimum segment length α min

Non-invasive sampling and chemical analysis of breath gases could provide valuable information related to health and well-being. Breath gases are indicators of metabolic end products. The objective of this research was to design, assemble... more

Non-invasive sampling and chemical analysis of breath gases could provide valuable information related to health and well-being. Breath gases are indicators of metabolic end products. The objective of this research was to design, assemble and test a new facemask-like device for on-site bovine breath sample collection with solid-phase microextraction (SPME). The new device consists of a cylindrical container, a sealing membrane for enclosure of nostrils and mouth of cattle, a system of filters and one-way valves, and sampling ports sealed with septa facilitating insertion of air sampling probes inside the device. An experiment was conducted to examine the feasibility of detecting volatile organic compounds (VOCs) exhaled by calves using this device. Solid-phase microextraction was used to collect rapid on-site breath samples. Divinylbenzene/Carboxen/ polydimethylsiloxane (DVB/Carboxen/PDMS) 50/30 mm and PDMS 100 mm SPME fibres and sampling times ranging from 5 to 15 min were used. The SPME-based samples were sealed and transported to the laboratory and analysed with chromatography-mass spectrometry (GC-MS). Acetone, methyl ethyl ketone, toluene, tetradecane, pentadecane, nonanal and decanal were identified in cattle breath. A simple sampling system, combined with SPME-based sampling and analysis with GC-MS was very useful for fast collection and detection of bovine breath gases. The DVB/Carboxen/PDMS 50/30 mm fibre coating, sealing caps, and refrigeration worked well for retaining compounds found in breath samples. Solid-phase microextraction was also valuable for detection of residual VOCs in the breath sampling device that resulted in optimisation of cleaning procedures. The device can be easily adapted for other animals by adjusting the size of the cylindrical container and/or by replacing the sealing membrane with more suitable opening.

The actual quantity of product units in pre-packed packages is an issue that concerns both the consumer and the producer. The consumer has the right to expect packages to bear accurate net content information, and the producer aims to... more

The actual quantity of product units in pre-packed packages is an issue that concerns both the consumer and the producer. The consumer has the right to expect packages to bear accurate net content information, and the producer aims to pack the specified nominal quantities at minimum cost. Routine verification of the net contents of packages is an important part of any weights and measures programme intended to facilitate value comparison and fair competition. The American National Institute of Standards and Technology (NIST) has developed a procedural guide (NIST Handbook 133) for testing the compliance of net content of packaged goods. This handbook is used by government officials, and by commercial and industrial establishments, in connection with packing, distribution, and sale of commodities. Manufacturers whose products are sold in such packages have the right to expect that their competitors will be required to adhere to the same standards. The present study presents a methodology that supports the count-toweight transform of pre-packed packages of products with wide variability of characteristics. The analytical model developed guides the manufacturer on how to satisfy the NIST Handbook 133 requirements, while ensuring that the package will not be overfilled, as usually occurs in manual packaging of these products. (G. Vitner).

Two machinery operations in two different fields were monitored and analysed. The operations involved slurry applications carried out by machinery systems involving an application unit (AU) and a refilling unit (RU). The application... more

Two machinery operations in two different fields were monitored and analysed. The operations involved slurry applications carried out by machinery systems involving an application unit (AU) and a refilling unit (RU). The application systems consisted of an uncontrolled traffic farming (UCTF) system and the controlled traffic farming (CTF) system.

A bidimensional finite element model that predicts temperature distribution and moisture migration of wheat stored in silobags due to seasonal variation of climatic conditions is described. The model includes grain respiration and... more

A bidimensional finite element model that predicts temperature distribution and moisture migration of wheat stored in silobags due to seasonal variation of climatic conditions is described. The model includes grain respiration and calculates carbon dioxide and oxygen concentrations during storage as well as the associated dry matter loss.

In this study, the influence of air temperature, velocity and humidity on the thin-layer drying of rosehip was investigated. A laboratory air drier was designed and used for drying experiments. The system was operated in an air... more

In this study, the influence of air temperature, velocity and humidity on the thin-layer drying of rosehip was investigated. A laboratory air drier was designed and used for drying experiments. The system was operated in an air temperature range of 50-801C, air velocity range of 1Á67-3Á10 m s À1 and air absolute humidity range of 0Á005-0Á08 kg [vapour] kg À1 [dry air]. Six mathematical models available in the literature were fitted to the experimental data. By statistical comparison of the values for the six models, it was concluded that the logarithmic model represents drying characteristics better than the other equations.

Indicators are suitable tools to analyse the environmental effects of intensive agricultural cultivation, and their description and quantification can be used by local authorities to carry out decisions to contain the impact on the... more

Indicators are suitable tools to analyse the environmental effects of intensive agricultural cultivation, and their description and quantification can be used by local authorities to carry out decisions to contain the impact on the environment within adequate thresholds.

The trial compared the use of needle and plate electrode configuration (corona discharge) with parallel plate electrode configuration for postharvest treatment of apples (Malus domestica Borkh, cv. Fuji and Golden Delicious) during... more

The trial compared the use of needle and plate electrode configuration (corona discharge) with parallel plate electrode configuration for postharvest treatment of apples (Malus domestica Borkh, cv. Fuji and Golden Delicious) during storage. The effect of electric field direction on physicochemical properties of fruit was also investigated. In Fuji apple storage, physicochemical parameters varied with water core content. Treatment of apples kept between parallel plate electric field suppressed weight loss unlike in the corona discharge field. Respiration and climacteric peak were suppressed in apples kept between parallel plate electric field. In corona discharge, after 7 days more respiration was noted in the treated than the untreated samples. The 'reversed' electric field treatment (apples on cathode plate) gave higher weight loss than the corresponding 'forward' electric field treatment (apples on anode plate) in the parallel plate arrangement. In corona discharge, the multiple of evaporation rate (ratio of water loss in treated sample to that of untreated sample) was higher for the 'forward' electric field direction (negative needle polarity) than the 'reversed' electric field direction (positive needle polarity).

A laser beam directed towards weeds can be an efficient weed control method as an alternative to herbicides. Lasers may deliver high-density energy to selected plant material, raising the temperature of the water in the plant cells and... more

A laser beam directed towards weeds can be an efficient weed control method as an alternative to herbicides. Lasers may deliver high-density energy to selected plant material, raising the temperature of the water in the plant cells and thereby stop or delay the growth. A commercial use of lasers for weed control, however, require a systematic investigation of the relationship between energy density and the biological effect on different weed species, growth stages, etc.

The vehicle routing problem (VRP) has been characterised as one of the great success stories of operational research, providing and facilitating, for over fifty years, optimal planning solutions for vehicle fleets in a large number of... more

The vehicle routing problem (VRP) has been characterised as one of the great success stories of operational research, providing and facilitating, for over fifty years, optimal planning solutions for vehicle fleets in a large number of real-life applications. In its simplest form, a VRP can be described as the problem of determining least-cost routes from one depot to a set of geographically dispersed ''customers'' (such as cities, stores, warehouses, and schools). VRP constitutes one of the most challenging combinatorial optimisation problems. A large number of different approaches have been developed over the years and a number of software packages are available on the market. In the agriculture, the VRP has only very recently been applied to the planning and execution of in-field operations, despite the fact that almost all agricultural field operations (AFO) inherently involve the motion of vehicles. In this paper, a dedicated classification of AFO is devised and tailored to a conceptual application of the VRP within the domain of agricultural field logistics. The concept regards the operations of primary agricultural machines, with the worked tracks in the field representing the ''customers'' using VRP methodology. By casting the agricultural fleet management problem in the framework of well-known VRP instances, over half a century of research and implementation experience can be brought to bear on the problem. This will provide for the enhanced management of conventional machinery systems, as well as, the mission and route-planning aspects of the high level control of emerging field robots.

In the arid and semi-arid regions of the southeast of Spain, the low availability of water for irrigation requires the development of new water-conserving irrigation techniques. This leads to the use of precision agriculture technologies... more

In the arid and semi-arid regions of the southeast of Spain, the low availability of water for irrigation requires the development of new water-conserving irrigation techniques. This leads to the use of precision agriculture technologies that permit an improvement in performance or reductions in the consumption of water and fertilisers. In this context, the use of digital photography enables plant growth monitoring, which allows crop water requirements to be determined from variables that are directly related to evapotranspiration.

Instrumented spheres are used worldwide in food processing chains to locate bruising risk zones and to prevent quality loss of commodity. Risk zone location and optimisation of machine settings can be executed with a satisfying accuracy... more

Instrumented spheres are used worldwide in food processing chains to locate bruising risk zones and to prevent quality loss of commodity. Risk zone location and optimisation of machine settings can be executed with a satisfying accuracy by comparing test results mutually, but measurement data are often hard to interpret, especially if predictions are desired on real damage. An extensive knowledge of the instrumented device and indications on the bruise susceptibility of a product are two indispensable conditions for successful damage prevention and reduction. As data acquisition techniques become more sophisticated and the autonomy of the measurement equipment tends to be better, the new generation of electronic potatoes, such as the Danish made PTR 200, seems promising for bruise prevention purposes. This is mainly due to improved memory capacity and more accurate data acquisition techniques.

In this study, computational fluid dynamics (CFD) was utilised to investigate the flow characteristics around tree windbreaks. The efficiency of windbreaks depends on many factors which can be investigated in field experiments, though... more

In this study, computational fluid dynamics (CFD) was utilised to investigate the flow characteristics around tree windbreaks. The efficiency of windbreaks depends on many factors which can be investigated in field experiments, though this is limited due to several reasons such as unstable weather conditions, few measuring points, etc. Fortunately, the investigation is possible via computer simulations. The simulation technique allows the trees to be modelled as a porous media where the aerodynamic properties of the trees are utilised in the model. The trees employed are Black pine trees (Pinus thunbergii) with a drag coefficient value of 0.55. The simulation provides analysis of the effect of gaps between trees, rows of trees, and tree arrangements in reducing wind velocity.

Agricultural machinery drivers are exposed to low-frequency vibrations during their work. The terrain profile, the long operating times, the forward speed of the agricultural machine and the sitting position are the key factors that lead... more

Agricultural machinery drivers are exposed to low-frequency vibrations during their work. The terrain profile, the long operating times, the forward speed of the agricultural machine and the sitting position are the key factors that lead to the suffering of the back of the agricultural machinery drivers. Suspensions systems are produced in order to reduce the health risks and the discomfort to the driver and to enable the driver to work at a faster pace. The suspension systems isolate the driver from the machine vibrations as much as possible.

ABSTRACT An agricultural tractor seat with non-linear stiffness and on–off damper offers a number of advantages when compared with traditional and currently, commercially available designs. These advantages are discussed within the... more

ABSTRACT An agricultural tractor seat with non-linear stiffness and on–off damper offers a number of advantages when compared with traditional and currently, commercially available designs. These advantages are discussed within the context of the constraints imposed by the restricted seat travel space. It is known that a soft suspension system with low natural frequency offers more comfort than a stiffer one, and also, that the former requires more travel space. It is also known that conventional dampers tend to be a compromise between limiting seat motion around the natural frequency and having good attenuation of higher-frequency inputs. This work shows that having the damper switched on for low-frequency ‘harsh’ bumps and off for higher-frequency inputs reduces seat accelerations while preventing end stop impacts. Experiments on a non-linear stiffness seat and on-off damper indicate that a 40% reduction in root-mean-square (RMS) acceleration compared to the linear, passively damped seat is obtainable, with no end stop impacts. This design has the additional advantage that it is cheap and robust.

Future technology in horticultural biosystems includes reflective ground covers to improve fruit quality including fruit colouration, firmness and sugar content. Optimal optical properties remain obscure, but it is well-known that... more

Future technology in horticultural biosystems includes reflective ground covers to improve fruit quality including fruit colouration, firmness and sugar content. Optimal optical properties remain obscure, but it is well-known that visible, particularly red, light as well as UV-B light, enhance colouration of fruits such as apple, peach, grape, plum, kaki and persimmon. The objective of this paper was to examine the reflection of four materials with potential suitability as ground covers (paper, aluminium foil, composite and polypropylene) to aid finding the optimal material for this purpose and its spread area. Spectral (M.M. Blanke).

A simulation model of a spinning disc fertiliser spreader developed for incorporation into an automatic control system design is described. Comparisons of the model simulation results to real measured results showed unacceptably high... more

A simulation model of a spinning disc fertiliser spreader developed for incorporation into an automatic control system design is described. Comparisons of the model simulation results to real measured results showed unacceptably high discrepancies between the two. Discrepancies were significantly reduced to acceptable levels when the parameters of the particle 'landing area' on the disc were used in the calculations rather than those of the orifice area, thus confirming the validity of the model. Particle 'landing area' is a manifestation of phenomena unaccounted for by the model and is dominated by the various particle interactions that occur during flow. Particle interactions are sensitive to spreader configurations, fertiliser characteristics as well as environmental factors. Calibration of model was performed to quantify dependence of 'landing area' parameters on a variety of spreader settings under controlled environmental conditions and for one fertiliser type. Achieved calibration curves can be used in a control system design to determine necessary adjustments to other control parameters to maintain shape of the distribution pattern when flow rate is adjusted.

In computational fluid dynamics (CFD) analyses, insect-proof screens are usually simulated as porous media. In applying the porous medium approach, the Forchheimer equation with published correlations for the permeability K and inertial... more

In computational fluid dynamics (CFD) analyses, insect-proof screens are usually simulated as porous media. In applying the porous medium approach, the Forchheimer equation with published correlations for the permeability K and inertial factor Y are usually used. In the present study, a comparison between simulations of flow through a realistic woven screen and a porous slab that represented the realistic woven screen indicated that using the published relations for K and Y may lead to erroneous results for pressure drops through screens. An alternative way, basically similar to that used in previous studies, for calculating K and Y is presented; it led to good estimates of pressure drops through various porous media slabs that were used to simulate realistic screen geometries.

The dynamics of a vertical suspension for a 39 m wide boom on a John Deere crop sprayer was optimised. The optimisation was based on a mathematical model of the suspension with an existing non-linear Koni s damper characteristic. During... more

The dynamics of a vertical suspension for a 39 m wide boom on a John Deere crop sprayer was optimised. The optimisation was based on a mathematical model of the suspension with an existing non-linear Koni s damper characteristic. During the optimisation, several tracks, which are based on power spectral densities of measurements in different field conditions, are applied to the suspension. The objective function to be minimised is the standard deviation of the absolute boom rotation around the horizontal axis while applying the tracks. As the model is simple but accurate, computation time is small such that many different field situations can be imposed during optimisation. By playing with the distance to the rotation point of the damper and selection of the appropriate damping value, the optimum could be realised.

A series of 168 pull-out tests were completed on samples of all-softwood pegged mortice and tenon connections fabricated using carpentry practices common to the UK, USA, Japan and Taiwan. Following testing, the connections were dissected... more

A series of 168 pull-out tests were completed on samples of all-softwood pegged mortice and tenon connections fabricated using carpentry practices common to the UK, USA, Japan and Taiwan. Following testing, the connections were dissected to allow observations of the failure mode and the effects of the end distance in the tenon, edge distance in the mortice, peg diameter and cross-section. Relative stiffness of the peg and the surrounding connection material, determined by geometry, was shown to influence the mode of failure and elastic connection behaviour. For the pegged mortice and tenon connections to perform to their full capacity in the softwood base material, 2d and d end distances are required for connections with 12 and 18 mm pegs, respectively, where d is the diameter of peg. A minimum of 2d edge distance is recommended to prevent wall failure in the mortice and for joints to perform to their full capacity for both 12 and 18 mm pegged connections.

Climate control for housed animals is of substantial importance but it is also a difficult and complicated task. The animals in a livestock building affect temperature and humidity conditions inside the building in a non-linear way, and... more

Climate control for housed animals is of substantial importance but it is also a difficult and complicated task. The animals in a livestock building affect temperature and humidity conditions inside the building in a non-linear way, and add long time constants to the system response. Moreover, the inherent coupling of temperature and humidity through psychrometric laws as well as the thermally dynamic nature of livestock buildings suggest that disturbance attenuation (load control of external environmental conditions, heat emanated by the animals and water-vapour production of animals) is far more important than is the case of other types of buildings. To settle these concerns, a non-linear control design method, resulting in an inherently robust adaptive non-linear proportional integral control law for simultaneous temperature/humidity control of livestock buildings in both summer and winter conditions, is presented in this paper. The proposed method, successfully tested here through extensive simulation, relies on: (a) a model-based feedback/feed-forward compensation of measured external disturbances on the basis of input–output linearisation, decoupling and Lyapunov theory; (b) a robust non-linear compensation of unknown external system disturbances and parametric uncertainties, on the basis of non-linear damping terms, to guarantee small output deviations from desired set-point values; and (c) an adaptive non-linear control law incorporating integral action to cope for parametric model uncertainty and unknown disturbances and to guarantee zero steady-state offset in the system response. Its ability to track varying set-points provides the possibility to combine it with higher level control modules useful for the transformation of user-defined settings for temperature and humidity into feasible controller set-points, taking into account the constraints imposed by the capacities of the actuators, the psychrometric laws, animal welfare, etc. The proposed method is applicable to any air-conditioning system and is expected to gain wide acceptance in modern climate control systems.

An innovative biodegradable coating that can be sprayed was developed and tested as suitable alternative to low density polyethylene (LDPE) films for soil mulching in horticulture. A mulch was created by spraying onto the soil a sodium... more

An innovative biodegradable coating that can be sprayed was developed and tested as suitable alternative to low density polyethylene (LDPE) films for soil mulching in horticulture. A mulch was created by spraying onto the soil a sodium alginate water-based solution that, at the end of the cultivation cycle, could be tilled into the soil to be biodegraded. The mechanical and radiometric properties, the functionality of the spray coating, and its biodegradation were assessed by means of laboratory measurements and cultivation field tests. In the field, during the cultivation of strawberries, the spray coating was compared with a LDPE mulching film and a straw mulch. The mechanical properties of the coating degraded when exposed in the field, but the coating kept its mulching effect for 6 months. The radiometric properties varied without regular trends, but the coating maintained its capacity to suppress weeds. The biodegradation tests showed that the spray coating samples biodegraded by 65% after 6 months into the soil. (G. Vox).

Lab report produced for Agricultural Process Engineering subject

Coordinate transformations were used to simulate the kinematics of a rotary tillage, C type blade. Using three-dimensional computer graphics, a Bezier surface of the rear surface of the blade was generated. The error in generating the... more

Coordinate transformations were used to simulate the kinematics of a rotary tillage, C type blade. Using three-dimensional computer graphics, a Bezier surface of the rear surface of the blade was generated. The error in generating the surface remained below 1·2, 5 and 8 per cent for the x, y and z coordinates, respectively, joining multiple Bezier surface patches. The analysis was carried out at rotor speeds of 180, 200 and 220 min−1 and at tractor forward speeds of 3, 3·25 and 3·5 km h−1 and for two blade orientations: namely, 0° and 20°. The interaction of the blade with soil during its operation was analysed using a scan of trochoidal paths of the leading and trailing edges of the blade (LT scan) computer programmed in language C/C++. Interference of the trailing edges of the blade with uncut soil was eliminated by design changes and checked with LT scans for the range of selected rotor speeds and forward speeds. The rectified surface was manufactured using high carbon steel.

To investigate the structural stability of horizontal silo walls, a silo (length, 27 m; width, 9.1 m) with straight panels (length, 3 m; thickness, 0.16 m; height above the floor, 2.05 m) on one side and L-shaped wall panels (length, 4 m;... more

To investigate the structural stability of horizontal silo walls, a silo (length, 27 m; width, 9.1 m) with straight panels (length, 3 m; thickness, 0.16 m; height above the floor, 2.05 m) on one side and L-shaped wall panels (length, 4 m; thickness, 0.15 m at the bottom to 0.10 m at the top; height above the foot, 1.85 m) on the other side was constructed on the à Corresponding author.

This work focuses on the operational characterisation of a fogging system in combination with forced ventilation for cooling greenhouses. This cooling system was installed and operated according to the following scheme: highpressure spray... more

This work focuses on the operational characterisation of a fogging system in combination with forced ventilation for cooling greenhouses. This cooling system was installed and operated according to the following scheme: highpressure spray nozzles with the highest possible uniformity of distribution, fans at both ends of the greenhouse (north and south) placed at ground level, roof openings and two side openings (east and west). The results obtained revealed that inside the greenhouse air temperature and relative humidity of 288C and 80%, respectively, were maintained during the summer at midday. Furthermore, the results obtained revealed generally high uniformity of the climatic conditions (the same magnitude of temperature measurements error }AE0Á58C), within the greenhouse, in the lengthwise (north-south) and vertical directions. In contrast to that, there was significant variation across the width of the greenhouse (east-west), which arose as a result of wind action; however, under the conditions of a greenhouse with developed plants or with the windward openings closed, uniform conditions were obtained. It must be concluded that in order to obtain completely uniform climatic conditions throughout the volume of the greenhouse, it is desirable to install fans in all four sides. Such an arrangement may make possible: uniform climatic conditions within the desired range, even in the summer months; good control over the climatic conditions through reduction of the influence of the wind; operation of the greenhouse by means of a relatively simple control system; the establishment of greenhouses in large units and, consequently, better exploitation of the land area and significant reduction in the cost per unit area of the structure.

A systems model has been developed to support the process of choosing the optimal level of farm mechanisation in terms of technical capability. The optimisation model is a non-linear programming model implemented by using the programming... more

A systems model has been developed to support the process of choosing the optimal level of farm mechanisation in terms of technical capability. The optimisation model is a non-linear programming model implemented by using the programming software suite General Algebraic Modelling System (GAMS). It is based upon a least-cost concept involving all expected fixed and variable costs (including timeliness costs) for a particular farm size and crop plan. The output from the model is the sizing of each machine, and also the tractor power and number of tractors required. The effective work rates of the machinery sets and the duration in nominal time for performing each operation are also shown. The selection is based upon a farm-oriented matrix involving various types of constraints, such as available man-hours, available machine-and tractorhours, timeliness and workability of operations, agronomic window of operations, and sequence of operations.

An analysis of the motion of a particle on a rotating flat disc is conducted and a basic equation of motion derived for a single particle. The analysis is directly applied to the flow of particles on a centrifugal fertiliser spreader.... more

An analysis of the motion of a particle on a rotating flat disc is conducted and a basic equation of motion derived for a single particle. The analysis is directly applied to the flow of particles on a centrifugal fertiliser spreader. Equations of motion are derived for flat disc/radial vanes type of spreaders and further generalised for the more common conical disc/pitched vanes type. The derived equations of motion form part of the basis of a simulation model for centrifugal (or spinning disc) fertiliser spreaders with the equations of motion through the air completing the model. In the simulation, the collective flow of particles is treated as a superposition of single-particle trajectories with different initial conditions. The spreader model is applicable for the development of spreader control systems for site-specific fertiliser application as well as for the design and optimisation of spreaders.

Thin-layer drying behaviour of raw mango slices was studied in a laboratory model tunnel dryer. The samples were dried at 55, 60 and 65 1C air temperature with control, blanching and blanching in 1% potassium metabisulphide (KMS) solution... more

Thin-layer drying behaviour of raw mango slices was studied in a laboratory model tunnel dryer. The samples were dried at 55, 60 and 65 1C air temperature with control, blanching and blanching in 1% potassium metabisulphide (KMS) solution as pre-treatments. Six thin-layer drying models (Newton, Page, Modified Page, Henderson and Pabis, logarithmic and Wang & Singh) were fitted to the moisture ratio data. Among the drying models investigated, the Page model satisfactorily described the drying behaviour of raw mango slices. The effective moisture diffusivity varied from 2Á62 Â 10 À10 to 4Á39 Â 10 À10 m 2 s À1 .

The effect of ventilation configuration of a tunnel greenhouse with crop on airflow and temperature patterns was numerically investigated using a commercial computational fluid dynamics (CFD) code. The numerical model was firstly... more

The effect of ventilation configuration of a tunnel greenhouse with crop on airflow and temperature patterns was numerically investigated using a commercial computational fluid dynamics (CFD) code. The numerical model was firstly validated against experimental data collected in a tunnel greenhouse identical with the one used in simulations. The airflow patterns were measured and collected using a three-dimensional sonic anemometer and the greenhouse ventilation rate was deduced using a tracer gas technique. A good qualitative and quantitative agreement was found between the numerical results and the experimental measurements. After its validation, the CFD model was used to study the consequences of four different ventilator configurations on the natural ventilation system. The ventilation configuration affects the ventilation rate of the greenhouse and the airflow and air temperature distributions as well. For the different configurations, computed ventilation rates varied from 10 to 58 air changes per hour for an outside wind speed of 3 m s À1 and for a wind direction perpendicular to the openings. Likewise, the simulations highlight that while the mean air temperature at the middle of the tunnels varied from 28Á2 to 29Á88C, for an outside air temperature of 288C, there are regions inside tunnels 68C warmer than outside air. Average air velocity in the crop cover varied according to the arrangement of the vents from 0Á2 to 0Á7 m s À1 . The consequences of the marked climate heterogeneity on plant activity through the variation of crop aerodynamic resistance as well as the influence of the vent configurations on the efficiencies of ventilation on flow rate and air temperature differences between inside and outside, are also discussed.

After extrusion, the optimal moisture content of pasta is attained through drying, taking into account energetic and bio-physical concerns. Monitoring the moisture content of the pasta after the extrusion process, but before the drying... more

After extrusion, the optimal moisture content of pasta is attained through drying, taking into account energetic and bio-physical concerns. Monitoring the moisture content of the pasta after the extrusion process, but before the drying process, is useful as the moisture content is variable and may be used to adapt the air characteristics during drying. In this paper, near-infrared (NIR) reflectance spectroscopy is proposed for in-line determination of moisture concentrations in semolina pasta immediately after the extrusion process. Several pasta samples with different moisture concentrations were extruded while the reflectance spectra between 308 and 1704 nm were measured at the extrusion die. An adequate prediction model for the in-line moisture concentration was developed based on the Partial Least Squares (PLS) method using leave-one-out cross-validation. Best cross-validation results were obtained for non-transformed data, confirming the ability to predict excellently the moisture concentration of the extruded pasta (coefficient of determination r 2 CV ¼ 0.956; root-mean-square error of cross-validation RMSE CV ¼ 0.024 kg/kg). Comparable cross-validation results were obtained based on the most important wavelengths (when at least two different wavelengths were used). This creates opportunities for measuring the moisture content with a low-cost sensor.