快走丝线切割机床断丝故障分析与对策

对快走丝线切割机床断丝故障发生的原因进行了全面分析,并根据不同的断丝原因提出了相应的预防对策。     

苎麻牵切纺纱的牵切工艺探讨

本文主要分析了新型苎麻牵切机各项工艺参数对最终麻条质量的影响，主要包括皮辊，加压、牵切区隔距、预牵切区隔距、牵切区牵伸倍数。     

水炭运筹下稻田土壤氮素分布与盈亏15N示踪分析

为揭示水炭运筹下铵态氮、硝态氮在不同土层的分布规律和土壤氮素在水稻植株中的分布规律,设置两种水分管理模式(浅湿干灌溉、常规淹灌)和4个秸秆生物炭施用量水平(0、2. 5、12. 5、25 t/hm~2),采用田间小区和~(15)N示踪微区结合的方法,研究了不同水炭运筹下0～60 cm土层NH_4~+-N、NO_3~--N和肥料NH_4~+-~(15)N、NO_3~--~(15)N的累积分布,以及土壤氮素在水稻植株中的分布情况,并计算了不同水炭运筹下的土壤盈亏状况。试验结果表明:浅湿干灌溉模式下,稻田土壤中的NH_4~+-N累积量随土层深度的增加而减小,施加适量的秸秆生物炭增加了0～20 cm土层NH_4~+-N、NO_3~--N累积量,同时减少了20～60 cm土层的累积量。相同秸秆生物炭施用水平下,浅湿干灌溉模式0～20 cm土层中NH_4~+-N、NO_3~--N累积量和肥料NH_4~+-~(15)N、NO_3~--~(15)N累积量均高于常规淹灌模式,浅湿干灌溉模式20～40 cm和40～60 cm土层NO_3~--~(15)N累积量较常规淹灌模式显著降低(P 0. 05)。浅湿干灌溉模式积累的土壤氮素有9. 79%～13. 96%分布在植株叶片,15. 71%～20. 03%分布在植株茎鞘,66. 00%～74. 50%分布在植株穗部。综合考虑寒地黑土区土壤氮库盈亏平衡,浅湿干灌溉模式施加12. 5 t/hm~2秸秆生物炭的水炭运筹模式最优。     

甘肃省淤地坝工程的溃坝风险评价模型

[目的] 运用淤地坝工程溃坝风险评价模型,确定淤地坝工程发生溃决可能性的大小,为淤地坝运行管理提供技术支撑。[方法] 通过调研和对溃坝风险问题的梳理,形成淤地坝工程溃坝风险评价指标体系,运用层次分析法确定指标权重,构建了甘肃省淤地坝工程溃坝风险评价模型。[结果] 该模型包含水文风险（B₁）、运行风险（B₂）、管理风险（B₃）、工程风险（B₄）4个风险类型模块（其权重分别为0.12,0.13,0.12,0.63）及其下的16个具体评价指标;水面/泥面距拦泥坝高的距离（D₁）、剩余淤积库容（D₄）、有无3个管理负责人（D₇）、坝体变形（D₁₂）分别是4个风险类型模块的最大权重评价指标;对各指标的评分标准作了规定,依据综合风险得分将输出的风险等级和预警等级各划分为3级。[结论] 淤地坝工程溃坝风险评价模型由输入、分析和输出3个模块组成,层次清晰,架构明确。评估模型的构建可对汛期淤地坝工程风险的评价提供实时预警数据。     

极端降雨条件下小流域淤地坝系连溃风险分析

近年来,黄土高原上的淤地坝在减轻水土流失、淤地造田等方面发挥了重要作用.但相较土石坝,淤地坝的防洪标准不高,更容易发生溃坝.淤地坝多以梯级形式分布在若干小流域中,构成了一个复杂的坝系网络,为正确评价溃决风险带来很大的挑战.采用一种基于小流域水文计算和考虑复杂入流条件的淤地坝系连溃风险分析模型及相应的计算程序FT-IWH...     

酰胺化低酯果胶在低糖果酱的应用研究

酰胺化低酯果胶具有较低酯果胶更优越的凝胶性质,在低糖果酱中应用广泛。以酰胺化低酯果胶为研究对象,研究不同钙离子添加量和不同固形物含量对低酯酰胺化果胶制备低糖果酱的凝胶强度影响,此外在一定条件下采用不同钙敏性酰胺化低酯果胶制备低糖果酱,研究酰胺化低酯果胶的成胶能力与其钙敏性的关系。研究表明,酰胺化低酯果胶较低酯果胶能在较宽的钙离子浓度范围内形成凝胶,且所需钙离子较少。固形物含量对酰胺化低酯果胶形成凝胶的凝胶强度有影响,随着固形物含量的增加,形成凝胶的凝胶强度增大。酰胺化低酯果胶在一定条件下的成胶能力与其钙敏性有关,钙敏性越高的酰胺化低酯果胶凝胶强度越高。     

基于变结构协整检验的都市农业景观演变阶段分析

为准确判定经济增长和农业景观面积变化的结构突变时点,划分都市农业景观演变阶段,该文以上海市西郊的青浦区为例,利用1978-2015年的经济和农业景观时间序列数据,采用Gregory-Hansen变结构协整检验对该区经济增长与农业景观面积变化进行分析。结果表明:长时段的不考虑结构突变点的协整检验方法,对处于经济社会快速转型期的上海市青浦区并不合适;而变结构协整方法能较好地反映长时段内经济和社会结构变化,体现该区经济和社会系统内部长期均衡关系;青浦区的经济增长是以牺牲农业景观资源为代价而实现的;1978-2015年青浦区农业景观演变可划分为3个阶段:低水平协同阶段(1978-1995年)、反向推动阶段(1995-2007年)和经济拉动阶段(2007-2015年)。该结果既有助于协调该区经济发展与农业景观资源保护问题,为土地空间整治提供重要的理论依据,又能对经济欠发达区域更好处理二者关系提供科学借鉴。     

沙米生长特性调查

通过对沙米生长特性、种群动态及其对水分的影响等方面系统的调查,探讨流动沙丘上若留有片状枯萎的沙米,（翌年）沙米植株之间就不再生长新生沙米的可能原因。同时,利用先锋植物的这种生态适应机制,探讨了沙漠地区短命植物适应干旱环境的生长特性。     

Modelling Agronomically-Suitable Sowing Date in Relation to the Risk of Frost Damage and Heat Stress of Wheat in Southern New South Wales,Australia

Sowing time of wheat in south eastern Australia varies from autumn to early winter, depending on the seasonal ＇break＇. Wheat yields are often reduced by frost damage at flowering time and by heat-and/or water-stress during grain filling. Selecting suitable varieties for specific sowing times is a complex decision farmers make because these varietal phenology and climate risks have to be assessed together. In order to help farmers make decisions, they need tools that simulate and analyse agronomically-suitable sowing dates （ASSD） for a given variety of wheat. The hypothesis underlining this study is the integration of a wheat phenology model with historical climate data is an effective approach to modelling the ASSD of current varieties used in the wheat growing areas of Southern NSW. The parameters of the wheat phenology model were based on data from five years of field experimentation across 15 sites. Data from four sites were used to examine varietal suitability in relation to sowing time and its associated risks of frost and heat damage. The optimum ASSD for any variety at 72 locations across Southern NSW was investigated. The results showed that there were substantial spatial variations in the ASSD across the target region. ASSD for a late maturing wheat genotype （EGA Gregory） can range from early March to late April, while the earliest acceptable sowing date for an early maturing spring wheat genotype （H46） can range from early to late May. The wide range of spatial variation in the earliest and latest sowing dates, as well as the varied length of sowing opportunities, highlighted the importance of being able to apply a modelling approach which can integrate information on crop phenology with climate risk for a given location. This approach would allow better decision-making on suitable varieties and sowing dates in order to minimise the risk of frost and heat damage affecting crop yield.     

Susceptibility of intercrops to infection with Rhizoctonia solani AG 2‐2 IIIB and influence on subsequently cultivated sugar beet

The susceptibility of intercrop species (Raphanus sativus, Brassica juncea, B. rapa, Sinapis alba and Phacelia tanacetifolia) to the sugar beet pathogen Rhizoctonia solani was investigated in vitro, in the greenhouse and in the field with artificial inoculation. Disease severity in subsequently cultivated sugar beet was monitored in the field. Differences in susceptibility between species were found to be consistent in all experimental systems. All intercrop species were susceptible to R. solani. Brassica rapa and R. sativus were less susceptible than P. tanacetifolia. Compared to fallow, the cultivation of B. rapa and R. sativus reduced disease severity in subsequently grown sugar beet (median ratings of up to 3·0 and 3·5, respectively, depending on environmental conditions). This resulted in higher white sugar yield compared to fallow (up to 210% and 157% for B. rapa and R. sativus, respectively). This study demonstrates that in vitro and greenhouse resistance tests are suitable systems to predict the effects of intercrop species susceptibility in the field on disease severity and white sugar yield in subsequently grown sugar beet. Intercrop breeding programmes might profit from fast and efficient screening tests to provide Rhizoctonia‐resistant intercrops as an additional control measure against R. solani in sugar beet.