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The new functionalities of www.aiia.it - technical note
No full textThe main funcniolaties of the renewed website of Italian Association of Agricultural Engineering, at the address www.aiia.it, are briefly described
Application of Constrained Optimization Techniques in Optimal Shape Design of a Freezer to Dosing Line Splitter for Ice Cream Production
Full text linkDesign of multiple branches splitting of equal mass flow rate in complex rheological flows like ice cream near melting point temperature can be a challenging task. Pulsations in flow rate due to air pumping process and small fluctuations in temperature affecting flow rheology can determine a consistent difference in internal pipe velocity distribution, resulting in a significant difference in the distribution of ice cream dosage. Computational sciences and engineering techniques have allowed a major change in the way products and equipment can be engineered, as a computational model simulating physical processes can be more easily obtained, rather than making prototypes and performing multiple experiments. Among such techniques, optimal shape design (OSD) represents an interesting approach. In OSD, the essential element with respect to classical numerical simulations in fixed geometrical configurations relays on the introduction a certain amount of geometrical degrees of freedom as a part of the unknowns. This implies that the geometry is not completely defined, but part of it is allowed to move dynamically in order to minimize or maximize an objective function. From a mathematical point of view, OSD is a branch of differentiable optimization and more precisely the application of optimal control for distributed systems. OSD is still today numerically difficult to implement, because it relies on a computer intensive activity and moreover because the concept of “optimal” is a compromise between shapes that are good with respect to several criteria. In this work, the applications of a multivariate constrained optimization algorithm is proposed in the case of a mechanical ice cream 1 to 5 splitting system, required to distribute in an evenly way from one freezer into five dosing valves. Results allowed to design a retro-fitting system on an existing production plant reducing the dosing error down to 3% on the average
Air Assisted Production of Alginate Beads Using Focusing Flow Microfluidic Devices: Numerical Modeling of Beads Formation
No full textAlginate micro-bead production represents an interesting technological application in many fields such as pharmaceutical, food, and cosmetics. Usually the studies of micro droplet or micro-bead creation in micro channels formed in different geometries and different techniques (mostly T channel or flow-focusing) have been the subject of many research studies using pure, well characterized solutions and do not take into account the behavior and interaction of food grade and natural products. The possibility of using air as focusing flow [2] in microfluidic devices to produce sodium alginate micro-bead introduce some advantages; for example, the utilization of different focusing fluids like oil frequently requires complicate production processes, introducing a barrier to the interaction of alginate solution with the calcium ions during gelification phase and requiring a posteriori filtering and washing procedure. Moreover, direct immersion of liquid alginate drops in a calcium chloride bath to induce gelification usually happens at relatively high speed, inducing a bead shape deformation due to inertial effects. As in microfluidics details really matter, the geometry of the device represents an important issue: small changes in geometrical configuration, like coaxial misalignment could results in major changes in the dynamics of droplet formation. In this work such effects are investigated using numerical analysis
Modeling in postharvest: A multiscale perspective
No full textThe development in plant physiology understanding together with the extension of mechanistic and hybrid models suggests that the use of models in the postharvest chain will always more extended in the next future. Modeling allows not only to verify experimental data under a unifying umbrella, but also to gain an insight in physical and biological process, to predict product characteristics and to optimize the postharvest chain at different scale levels. In this short review a multiscale point of view is presented.
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Computer simulation of radio-frequency heating applied to block-shaped foods: Analysis on the role of geometrical parameters
No full textDuring radio frequency (RF) processing, geometrical factors such as distance between electrodes and projection of top electrode on the samples' exposed surface area (area that electric field passes through the sample) have a certain effect on power absorption, temperature distribution, heating rates and heating uniformity in the samples. Knowing the role played by these factors can be helpful for further studies in optimization of design parameters of an RF heating process. Therefore, to evaluate effect due to distance between electrodes and projection area during RF heating process, samples of same volume but exhibiting different projection areas were used to determine the variability in their power absorption, temperature change and heating rates. RF electrodes in this system were positioned with a fixed gap between samples' top-bottom surfaces and the electrodes and, case by case, at different distance between electrodes. The results indicated that both parameters have strong effect on power absorption, temperature distribution, heating rates and heating uniformity in the samples, which is further amplified when it is combined with the change of dielectric properties with temperature. In the investigated range, wider projection area and shorter distance between electrodes led to faster heating, in terms of average temperature, but less uniform temperature distribution, at least in the early stage of the RF heating process, before the changes in dielectric properties of the heated load started modifying the trend of the loss tangent and penetration depth. The results of this study are expected to be used in planning geometrical configuration and design parameters of RF systems and sample dimensions for further optimization studies. © 2016 The Institution of Chemical Engineers
Analysis of Instantaneous IMU Acquisition for Safety Index Identification in Tractor Driving
No full textNumerical and experimental analysis of vertical spray control patternators
No full textThe experimental vertical spray control walls have the purpose of picking up the liquid delivered by trained sprayer for providing the liquid distribution profile in height. Theoretically this should correspond to the ideal profile, which consists in a uniform distribution on the vegetation. If the profile is different from the ideal, a parameter setup is required on the sprayer. Nonetheless, some problems are hidden in the aforementioned statements: i) no wall measures exactly the distribution profile (i.e. the flow through the sections in the vertical plane, parallel to the direction of advancement of the sprayer). Compared to real profile, sensitive errors are introduced: the evaporation of the drops, the deviation of the air flows caused by the sensors panel themselves; by the possibility that the drops bounce on the wall panels, also due to the current of air that can push the liquid veil laterally or upwards, Moreover, everything varies depending on the geometry of the sensors, air velocity, air humidity; ii) no one knows what exactly is the optimal distribution profile. It is often considered as optimal a profile that reflects the amount of leaf area subtended by each section absorber: however, it is evident that the path of the droplets changes according to the sprayer typology (eg. radial-flow or horizontal flows). In this work a combined numerical-experimental approach is adopted, in order to assess some of the aforementioned issues: numerical data obtained by using computational fluid dynamics models are compared and validated with experimental data, in order to assess the reliability of numerical simulations in configurations which are difficult to analyze using an experimental setu
First measurements of spray deposition obtained from UAV spray application technique
No full textPesticide application using UAV is gaining momentum as a possible crucial technical approach to control insect, diseases and weeds population on the field. To prevent large-scale spread of dissociation or pathogen, a drone can be used not only to record and determine the disease scale, but also for repressing further attack and spreading of diseases. In order to achieve the control of diseases and efficiency of the pesticide application, a pesticide deposition must reach destination target at maximum quantity. Adequate and even uniform pesticide application will increase the efficiency of the application. Deposit quantification analysis was done initially with water-sensitive paper. This method provided coverage data, but not the exact amount of the product that reached the targeted surface due to problem with reading in software. By using tracers, a quantification of the amount of pesticide that has reached the target is achieved. In this case, drone sprayer with flat fan nozzles have been used to test deposition quality of tracer in exchange for pesticides. Maximum deposition was recovered almost 31% of total spraying norm. More than 69% was loose as drift or in other ways. Average deposition of tracer under the drone was between 13.39% and 15.97% which mean that more over 84% are losses. The deposit of tracer is affected not only by wind drift, but also by vortex made by drone turbines
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