上海青浦优质稻米产业发展现状与对策研究

优质稻米产业是上海市青浦区现代农业主导产业,发展优质稻米产业是贯彻落实乡村振兴战略的重要措施。通过调查研究,分析青浦区优质稻米产业的发展现状和存在的问题,提出构建优质稻米标准化绿色生产体系、强化优质稻米品牌建设、组建优质稻米产业化联合体、拓宽优质稻米的营销渠道等对策和建议,以期为上海青浦地区优质稻米产业发展提供参考。

Spatial Pattern Characteristics and Influencing Factors of National Forest Cities in China

In view of the deficiency of national forest cities in the exploration of spatial pattern and influencing factors,this paper adopted the methods of nearest neighbor analysis,kernel density analysis and unbalanced index calculation to analyze the spatial agglomeration pattern and spatial differentiation pattern of national forest cities.The factors affecting the selection and distribution of national forest cities were investigated by using the geographic detector and GWR model.The research results show that:① National forest cities show a spatial aggregation pattern of “east and west sparse,gradient change”,whose distribution is closely related to the climatic area;② The number of national garden cities,forest coverage rate,urbanization rate and local general budget income are four factors that have significant influence on the selection and distribution of national forest cities;③ The four significant influencing factors all have different degrees of spatial non-stationarity,and their two-factor and nonlinear enhancement effects can be generated after two interactions,among which the enhancement effect is the most obvious when the local general budget income interacts with other factors.

基于正交试验的玻璃壳热应力影响因素分析

为研究江门中微子试验(JUNO)光电倍增管(PMT)玻璃壳在温度载荷下的应力分布,以避免玻璃壳发生脆性破坏,对不同灌封胶材料下的玻璃壳热应力进行有限元模拟分析。采用正交试验方法,选取灌封胶材料属性参数中的弹性模量、泊松比和热膨胀系数作为研究因素,建立L25(53)正交表并得到25组数值模拟方案。对数值计算结果进行极差和方差分析,结果显示影响设计指标的主要因素为弹性模量和热膨胀系数,次要因素为泊松比。弹性模量对玻璃壳热应力有显著影响,热膨胀系数对玻璃壳热应力有一定影响,泊松比对玻璃壳热应力无显著影响。对各因素水平的算术平均值进行曲线拟合,提出基于拟合函数解析解的敏度分析方法来得到设计指标对各因素的敏感程度。结果表明,玻璃热应力对不同灌封胶材料的各参数敏感度不同。实际工程可针对最大敏度参数进行材料的改性工作,从而使得灌封胶材料的选用和改性更具有针对性和方向性,研究结果对实际工程具有极强的指导意义和参考价值。