A procedure for determining the viscoelastic properties of apple flesh has been proposed based on compression tests and FEM optimization. Short-term simple compression tests and long-term relaxation tests were performed with cylindrical specimens of apple flesh to measure mechanical properties, and the viscoelastic behavior was predicted using FEM optimization models. Through short-term optimization, the elastic modulus and Poisson's ratio were determined by comparing two kernel functions based on 1) shear only and 2) shear and bulk terms. Long-term stress-relaxation behavior of the specimen was reasonably predicted by two FEM optimization steps within 3.8 % error. The FEM optimization algorithms developed in this research might be applied to determine the viscoelastic properties of bio-materials and also to predict mechanical behavior of these materials under various loading conditions.

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This study was intended to build 3D FEM geometry models of actual 'Fuji' apples by digitizing their surfaces, and to determine elastic modulus by FEM simulation based on the F-D curves of radial compression test from a point on apple equator. Also, the general protocol of ASAE S368.4 for predicting the apparent modulus of elasticity and the maximum contact stress for convex-shape food materials was evaluated for its appropriateness. The model apple for FEM analysis was composed of approximately 35,000 geometry elements that closely resemble the surface of an actual apple. Through FEM simulation, the average elastic modulus of 7.732 MPa was obtained at the loading condition of 0.5 BP, which was 8.3% smaller than the average apparent modulus of elasticity predicted by the ASAE standard. The maximum Von Mises stress at the points of initial contact with the compression target plates evaluated by FEM simulation was about 37% smaller than the maximum contact stress determined by the ASAE standard, and a poor correlation was found between the results of the two methods. These results could be explained by that a whole apple, in general, has an anisotropic structure with many complex and small curvatures, has fl esh texture bonded biologically, and is covered with more elastic membrane shell which contributes to prevent dehydration during compression.

The objective of this work was to establish a three-dimensional measuring method for the size, morphology and distribution of internal structure such as ice crystals, bubbles and solids content within an ice cream sample by using a cryogenic microtome spectral imaging system (CMtSIS). The 3-D images of ice crystals, bubbles and milk solids were recognized by reconstructing the circles in 2-D images into 3-D spheres; and the Overrun by Volume (ORV) was obtained by incorporating the area of bubbles on integrated image and the volume of bubbles in the 3-D image. Keywords: Ice crystal, Bubble, Internal structure, Spectral imaging, Micro- to macro-scale, Freeze-Drying

Aerial application using an unmanned agricultural helicopter would allow precise and timely spraying. The attitude of a helicopter depends on a number of dynamic variables for roll-balanced flight. Laterally tilting behavior of a helicopter is a physically intrinsic phenomenon while hovering and forwarding. In order to balance the fuselage, the rotor should be counter-tilted, resulting in the biased down-wash. The biased spraying toward right side causes uneven spray pattern.In this study, a raised tail rotor system for the roll-balanced helicopter was studied. Thrust of the tail rotor system was measured and theoretically estimated for the fundamental database of the roll-balanced helicopter design. The estimated tail thrust and roll-moment would be used to design the raising height of tail rotor and roll balancing dynamics.The unmanned agricultural helicopter required the tail rotor thrust of about 39.2 N (4.0 kgf) during hovering with a payload of 235.4 N (24 kgf). A raised tail rotor system would compensate for the physical tilt phenomena. A further attitude control system of helicopter would assist roll-balanced aerial spray application