典型果品机械损伤的多尺度实验研究及高光谱定量表征

Fruits will bear a variety of loads in the transport and storage process, which will bring micro- and meso-scale tissue damage, thus leading to a decline in fruit quality. At present, the damage mechanical behaviors research of fruits are concentrated in macroscopic mechanical properties and the micro-scale observation. Nondestructive assessment of the damage also falls on the classification of fruit quality and qualitative detection of damage and defects. In this proposal,a multi-scale experimental analysis of typical fruits’ damage behaviors will be carried out from macro-scale experimantal test to micro-scale in-suti loading and obzavation. The Non-destructive quantitative description and characterization of fruits’ mechanical damage will be studied. The mechanical parameters, which control the damage of fruit, will be explored and the conditions that cause the damage and the damage threshold will be determined. The damage evolution process of fruit tissues under external loads will be observed in micro-scale. The damage evolution law of different fruits will be analyzed. The factors that influence tissue damage will be explored. The relationship between micro-scale damage and macroscopic mechanical response will be built.In addition, a hyperspectral experimental mechanics technology will be developed and the nondestructive testing and quantitative characterization of fruits’ mechanical damage will be achieved. Finally, the damage mechanism of fruit tissue will be deeply understood by macro-mechanical experiments, micro-scale in situ loading and observations, necessary theoretical analysis and numerical simulations. Results are expected not only to enrich the theoretical system of biomechanics, but also to reduce postharvest losses of fruits.

果品在贮运过程中会受到多种载荷的作用，进而会给细胞组织带来损伤，从而影响果品的品质。针对目前对果品损伤力学行为的研究大多数还集中在宏观方面以及微观观察，对其损伤程度的无损评估也停留在果品质量的分级和缺陷、损伤的定性检测层面的现状，本项目拟在已有工作的基础上开展典型果品从宏观力学实验到微细观原位加载与观测分析的果品损伤力学行为的多尺度实验分析以及机械损伤的无损定量描述和表征的研究。探索控制果品损伤的力学参数，确定引起损伤的条件以及损伤阈值，从微细观尺度上观察果品细胞组织在外部载荷下的损伤演化过程，分析损伤演化规律，发现影响果品细胞组织损伤形式的因素，建立果品微细观损伤与宏观力学响应之间的关系，发展高光谱实验力学检测技术，实现果品机械损伤的无损检测和定量表征，最终达到深入理解果品细胞组织损伤机理的目标。研究工作在丰富生物力学理论体系的同时，对减少果品采后损耗有重要意义。

果品的力学特性与其组织结构、成分、品质变化密切相关，检测力学特性和质地能够反映果品贮藏中的品质变化。在这种情况下，果品的基本力学特性、损伤的机理分析、定量表征以及损伤程度的无损检测等成为该领域的关键性基础力学问题。高光谱成像技术凭借其定性、定量以及定位的能力，已经成为食品质量和安全检测、现代农业等领域最为活跃的一种检测手段。本项目研究了水果受机械损伤后其理化指标的变化，证明了水果理化指标的变化与其受损程度呈线性相关。基于高光谱成像技术实现了对水果（受损和未受损）理化指标的定量预测，进而实现了对水果受损程度的无损鉴别及预测。将感压胶片技术和压力扫描系统应用到水果的跌落损伤实验，巧妙提取样品的损伤面积值，通过建立水果损伤面积与其光谱变量的数学模型，实现了对水果损伤面积的无损预测。系统研究了水果在冲击载荷下的力学行为并实现了对其力学参数的高光谱无损预测。借助于高速相机系统和感压胶片技术，将水果的力学参数与其损伤面积联系起来并且找出影响损伤的主要贡献因子，最终采用高光谱成像技术对水果的力学参数进行了预测。同时，本项目还开发了一种结合主成分分析的损伤区域检测算法并将其应用于主成分图像，并基于所选区域提取光谱，主成分分析和连续投影算法用于选择特征波长，使用基于全波段和选定波长建立的支持向量机模型进行苹果机械参数的无损检测。研究成果不仅能丰富生物力学的理论体系，而且对于为果品低损伤收获、加工、贮运及质量检测等相关设备的研究提供理论依据，同时减少果品采后损耗，提高经济效益。