现有土壤与触土部件材料间的接触参数适用范围较窄,难以模拟高含水率下的作业状况。为了探索多种材料与不同含水率土壤的粘附情况,更加准确地解决触土部件与土壤的粘附问题,以南方稻茬田土壤为研究对象,应用EDEM中的Hertz-Mindlin with ...现有土壤与触土部件材料间的接触参数适用范围较窄,难以模拟高含水率下的作业状况。为了探索多种材料与不同含水率土壤的粘附情况,更加准确地解决触土部件与土壤的粘附问题,以南方稻茬田土壤为研究对象,应用EDEM中的Hertz-Mindlin with JKR Cohesion模型,对不同含水率的土壤与45号钢、超高分子量聚乙烯(ultra-high molecular weight polyethylene, UHMWPE)、聚四氟乙烯(polytetrafluoroethylene,PTFE)的接触参数进行标定。在前期试验的基础上,以碰撞恢复系数、静摩擦系数、滚动摩擦系数和JKR为试验因素,土壤的滚动距离为试验指标设计了Box-Behnken四因素三水平试验。最后对所得回归模型进行优化,得到了含水率21%、26%、31%(±1%)的土壤与45号钢、UHMWPE、PTFE的碰撞恢复系数、静摩擦系数、滚动摩擦系数以及JKR的最优参数。仿真滚动距离与实测滚动距离的最大相对误差为3.46%,说明标定的参数准确可靠,可以为触土部件在进行减粘脱附设计时提供参考。展开更多
为提高液熏腊肉风味品质及生产效率,以液熏腊肉为研究对象,改进烟熏液的传统使用方式,探究烟熏液辅助腌制液熏腊肉的加工工艺。以烟熏液体积分数、烟熏液添加量、腌制时间和烘烤时间为单因素影响因子,感官评分为响应值,进行响应面优化分...为提高液熏腊肉风味品质及生产效率,以液熏腊肉为研究对象,改进烟熏液的传统使用方式,探究烟熏液辅助腌制液熏腊肉的加工工艺。以烟熏液体积分数、烟熏液添加量、腌制时间和烘烤时间为单因素影响因子,感官评分为响应值,进行响应面优化分析,与传统湘西腊肉品质进行对比,并采用偏最小二乘判别分析(partial least squares-discriminant analysis,PLS-DA)对液熏腊肉烘烤过程中滋味物质的变化进行综合评价。结果表明:液熏腊肉最佳工艺条件为烟熏液体积分数70%、烟熏液添加量2%(m/m)、腌制时间4d、烘烤时间8d;相比市售湘西腊肉,液熏腊肉具有较高水分含量和亮度值,且食盐和亚硝酸盐含量更低,分别为3.8%和1.20mg/kg;液熏腊肉感官评分为84.56±1.10;通过滋味活度值分析可得,肌苷酸、鸟苷酸(guanosine monophosphate,GMP)、丙氨酸、谷氨酸、赖氨酸、精氨酸、缬氨酸、组氨酸及腺苷酸是液熏腊肉的主要滋味物质;PLS-DA表明,不同烘烤时间下液熏腊肉滋味物质含量存在差异,瓜氨酸、色氨酸、半胱氨酸、次黄嘌呤、GMP、谷氨酰胺、甘氨酸、异亮氨酸及亮氨酸是影响不同烘烤时间液熏腊肉滋味差异的关键指标。展开更多
Aerial threat assessment is a crucial link in modern air combat, whose result counts a great deal for commanders to make decisions. With the consideration that the existing threat assessment methods have difficulties ...Aerial threat assessment is a crucial link in modern air combat, whose result counts a great deal for commanders to make decisions. With the consideration that the existing threat assessment methods have difficulties in dealing with high dimensional time series target data, a threat assessment method based on self-attention mechanism and gated recurrent unit(SAGRU) is proposed. Firstly, a threat feature system including air combat situations and capability features is established. Moreover, a data augmentation process based on fractional Fourier transform(FRFT) is applied to extract more valuable information from time series situation features. Furthermore, aiming to capture key characteristics of battlefield evolution, a bidirectional GRU and SA mechanisms are designed for enhanced features.Subsequently, after the concatenation of the processed air combat situation and capability features, the target threat level will be predicted by fully connected neural layers and the softmax classifier. Finally, in order to validate this model, an air combat dataset generated by a combat simulation system is introduced for model training and testing. The comparison experiments show the proposed model has structural rationality and can perform threat assessment faster and more accurately than the other existing models based on deep learning.展开更多
文摘为提高液熏腊肉风味品质及生产效率,以液熏腊肉为研究对象,改进烟熏液的传统使用方式,探究烟熏液辅助腌制液熏腊肉的加工工艺。以烟熏液体积分数、烟熏液添加量、腌制时间和烘烤时间为单因素影响因子,感官评分为响应值,进行响应面优化分析,与传统湘西腊肉品质进行对比,并采用偏最小二乘判别分析(partial least squares-discriminant analysis,PLS-DA)对液熏腊肉烘烤过程中滋味物质的变化进行综合评价。结果表明:液熏腊肉最佳工艺条件为烟熏液体积分数70%、烟熏液添加量2%(m/m)、腌制时间4d、烘烤时间8d;相比市售湘西腊肉,液熏腊肉具有较高水分含量和亮度值,且食盐和亚硝酸盐含量更低,分别为3.8%和1.20mg/kg;液熏腊肉感官评分为84.56±1.10;通过滋味活度值分析可得,肌苷酸、鸟苷酸(guanosine monophosphate,GMP)、丙氨酸、谷氨酸、赖氨酸、精氨酸、缬氨酸、组氨酸及腺苷酸是液熏腊肉的主要滋味物质;PLS-DA表明,不同烘烤时间下液熏腊肉滋味物质含量存在差异,瓜氨酸、色氨酸、半胱氨酸、次黄嘌呤、GMP、谷氨酰胺、甘氨酸、异亮氨酸及亮氨酸是影响不同烘烤时间液熏腊肉滋味差异的关键指标。
基金supported by the National Natural Science Foundation of China (6202201562088101)+1 种基金Shanghai Municipal Science and Technology Major Project (2021SHZDZX0100)Shanghai Municip al Commission of Science and Technology Project (19511132101)。
文摘Aerial threat assessment is a crucial link in modern air combat, whose result counts a great deal for commanders to make decisions. With the consideration that the existing threat assessment methods have difficulties in dealing with high dimensional time series target data, a threat assessment method based on self-attention mechanism and gated recurrent unit(SAGRU) is proposed. Firstly, a threat feature system including air combat situations and capability features is established. Moreover, a data augmentation process based on fractional Fourier transform(FRFT) is applied to extract more valuable information from time series situation features. Furthermore, aiming to capture key characteristics of battlefield evolution, a bidirectional GRU and SA mechanisms are designed for enhanced features.Subsequently, after the concatenation of the processed air combat situation and capability features, the target threat level will be predicted by fully connected neural layers and the softmax classifier. Finally, in order to validate this model, an air combat dataset generated by a combat simulation system is introduced for model training and testing. The comparison experiments show the proposed model has structural rationality and can perform threat assessment faster and more accurately than the other existing models based on deep learning.
