不同保鲜膜对灵武长枣低温贮藏品质的影响

对灵武长枣低温贮藏前期3种包装袋袋内气体成分的变化进行了测定分析,同时将3种保鲜膜对枣果实低温贮藏90天的保鲜效果进行了研究。结果表明,微孔膜（KDM）保鲜效果好于打孔聚乙烯（PE）膜,不打孔PE膜最差,说明灵武长枣以使用气体通透性能较好的包装材料贮藏效果最佳,同时也证实了低温与专用保鲜剂结合专用薄膜自发气调的综合配套保鲜技术模式适用于灵武长枣贮藏保鲜．贮藏90天后好果率达87．5％。     

Near-isogenic lines of durum wheat: their development and plant characteristics

Summary The effect of specific plant characteristics on the grain and biomass yield of durum wheat can be accurately determined by using isogenic lines, which, however, were not usually available. This study reported the effects of long glume, glaucousness, glume pubescence, black glume and purple culm on the yield and its associated characteristics in near-isogenic lines of durum wheat cv. LD222, which were developed by continuous backcrossing. The long glume trait which resulted in a large photosynthetic area did not enhance yield. Increased glume size associated with the P gene tended to increase the main culm dominance, characterized such as vigorous main culm and weak tillers, and plant height, but to reduce tillering and spike number. Consequently, grain yield and harvest index declined. Under the adequate water supplying condition of the present study, the glaucous trait was beneficial for grain yield. The trait of glume pubescence did not excert any significant effect on the yield related characteristics in the LD222 background. The traits of black glume and purple culm reduced the number of spikes per unit area and the number of kernels per unit area.     

不含调压室的长引水管道水电站小波动稳定分析

具有长引水管道的中小型水电站,设置调压阀、爆破膜等调压措施后对大波动过渡过程中的内水压力变化和转速上升均能有较好的控制,但对机组的运行稳定性并无改善。通过假定水流为刚性水体,推导长距离输水管道系统理想水轮机下小波动微分方程组系数矩阵及其特征方程系数,根据Routh-Hurwitz稳定性判据,分别讨论了Tw和Ta以及PID调速器参数对小波动稳定域的影响,从而合理整定调速器的参数,保证小波动稳定。     

碳罐固定支架优化设计

通过对某款车型中碳罐固定支架初始结构设计所存在的两个主要问题（碳罐固定支架留在空间中的悬臂过长和在碳罐固定支架上的安装点连接强度相对较弱）,进行结构、装配关系等原因分析,然后根据这些原因问题进行结构优化改进。相应的结构改进包括：首先,通过缩短碳罐固定支架的悬臂长度用以减少其受力弯矩;其次,通过在碳罐固定支架周边增加翻边,来增加支架的强度,进而避免在支架折弯处产生变形或开裂。     

基于LSTM算法的智能节水灌溉预测模型研究

针对当前农田灌溉缺乏科学技术指导、水资源浪费严重的现状,为提高灌溉用水的利用效率,在智慧农业灌溉系统体系结构的基础上,提出了一种基于LSTM算法的智慧农业灌溉预测模型,可根据作物生长需求、生长环境和种植土壤等数据实现精准灌溉,能够最大程度地节约水资源.通过实验对LSTM灌溉预测模型与传统灌溉预测模型的预测值进行对比分析...     

基于SSA-LSTM的玉米土壤含氧量预测模型

土壤含氧量（Soil oxygen content,SOC）是影响作物生长的重要土壤环境因素之一,具有时序性、不稳定性和非线性等特点,精确预测土壤环境中含氧量的变化趋势,有助于制定更加合理的土壤通气增氧方案。本研究提出基于麻雀搜索算法（Sparrow search algorithm,SSA）和长短时记忆（Long and short-term memory,LSTM）神经网络预测模型,利用国家土壤质量湛江观测实验站记录玉米种植期间的气象环境和土壤环境数据,基于SSA-LSTM模型对SOC变化进行预测及相关性分析,并与传统的BP预测模型、LSTM预测模型、GA-LSTM预测模型及PSO-LSTM预测模型进行对比。试验结果表明,SOC与降雨量、土壤含水率、土壤温度、土壤充气孔隙度相关性极显著,相关系数高于0.8,与大气温度和风速相关性显著,与大气湿度和土壤呼吸速率相关性较弱。SSA-LSTM模型预测精度明显高于其他4组对照预测模型,R2达到0.95979,RMSE仅为0.4917%,MAPE为3.7331%,MAE为 0.3620%,预测值与试验值之间的拟合程度高。本研究可为土壤含氧量变化的精准预测及土壤通气增氧技术的应用推广提供理论支撑与科学依据。     

空气罐与超压泄压阀联合水锤防护特性

提出了一种空气罐与超压泄压阀联合设置的停泵水锤防护方案,并基于瞬变流计算的特征线法建立了空气罐、液控蝶阀、超压泄压阀等边界条件的数学模型,模拟了停泵工况下系统的压力变化过程.结合工程实例,对比分析了空气罐单独防护、空气罐与两阶段关闭泵后液控蝶阀联合防护以及空气罐与超压泄压阀联合防护对停泵水锤的影响.在空气罐体型一定时,对超压泄压阀的启闭规律进行了敏感性分析.计算结果表明,空气罐与两阶段关闭泵后液控蝶阀联合防护方案对输水系统正负水锤防护均不利;而空气罐与超压泄压阀联合防护方案对输水系统正负水锤均有较好的防护效果,与空气罐单独防护方案相比,泵后高压管段最高压应力由1.343 MPa降至1.087 MPa,在满足承压标准1.2 MPa的基础上安全裕度提高了9.4%,空气罐体型也由200 m³缩减至160 m³.超压泄压阀应在5 s内开启至全开度,且开启后持续时间应接近1个相长.     

Full Aero-elastic Bridge Model Design of Long Span Arch Bridge

Aero-elastic model design is the precondition of full bridge aero-elastic model tunnel tests. The full aero-elastic bridge model design of long span arch bridge is discussed. The effect on the model design of different transverse rod space and bend stiff is analyzed in detail. Different scheme need to be designed according to the transverse rod stiff. Considering the changing section dimensional arches, the method of projecting the spatial arches to the plane arches, then designing the plane arches, at last projecting the plane arches to the spatial arches is proposed at first. The results show that the method is effective.     

矮牵牛长柱头性状遗传分析

以闭花瓣型短柱头矮牵牛为母本,正常开放纯合型长柱头的矮牵牛作为父本,采用杂交、自交、回交方法,对不同世代的植株进行柱头长短调查统计分析,初步探讨了矮牵牛长柱头是由两对显性核基因控制的遗传,提出了转育长柱头闭花瓣型矮牵牛的遗传模式,以期获得长柱头闭花瓣型矮牵牛材料。     

温度对嫁接番茄幼苗生长及SOD、POD活性的影响

为探明华南地区番茄嫁接后的适宜生长温度,试验研究了3个温度处理下番茄嫁接苗的生长状况及其叶片内保护酶(SOD、POD)活性的变化。试验结果表明：20/17℃处理下地上部和根系生长都受到抑制,根冠比失调;30/27℃时植株出现徒长迹象,且整株生物量下降;25/22℃环境条件下,嫁接苗根冠协调,茎秆健壮,光合能力较强。相比于25/22℃环境,20/17℃的相对低温处理和30/27℃的相对高温处理下,番茄嫁接苗的SPAD读数分别下降20%和13%,叶片的SOD酶活性为237.58 U/(g?FW)和254.39 U/(g?FW),分别比25/22℃处理下的SOD活性低114 U/(g?FW)和97.19 U/(g?FW)。30/27℃处理下的POD活性高于另外两个处理,但差异不显著。综上所述,嫁接后的白天温度应控制在25℃左右,夜间温度为22℃左右。