基于霍尔效应的微小压强测量装置的设计与实现

针对化工液体的微小压强测量中所存在的测量复杂、精度低的问题，设计一种基于霍尔效应的测量流体微小压强变化的装置。该测量装置通过前端受力装置来承受液体压强的变化而产生一定的位移，并转换成霍尔电动势，经放大调理电路，最后接电压表显示相应的电压值。根据输出电压与液体压强之间的关系即可得到相应深度的压强大小。在实验中，电压表精确到1mV，最小可测量到0.792Pa的压强变化，其测量精度较高。该装置体积小、通用性强，具有较好的应用前景。     

自动润滑装置在数控无卡轴旋切机上的应用

数控无卡轴旋切机的刀台进给系统通过丝杠螺母的传动可实现刀体座的进退,传动丝杠螺母都是依靠人工润滑,如果润滑不及时就会出现粘牙现象而导致整个设备不能工作。介绍了一种自动润滑装置,其可实现对丝杠螺母的自动润滑。     

智能喷水灭火装置不同布置方式技术分析

在考虑喷水强度和喷水均匀性的基础上,文章针对智能喷水灭火装置的特性并综合国内一些工程实践经验,对智能喷水灭火装置的主要几种布置形式做出了技术分析比较,指出对于狭长型建筑物应采取单排布置形式,在多行列布置时宜被首选应用.     

气吸式大豆精密排种器排种性能试验研究

在精密播种机中,精密排种器是其工作的核心部件,工作性能直接制约了播种机播种性能的优劣。为了探究影响气吸式排种器工作性能的主次因素,以大豆气吸式排种器为研究对象进行了台架性能试验测试。试验确定排种盘转速为影响排种器排种性能的主次因素,气室负压为次要因素;排种盘转速为20 r/min,气室负压为5 k Pa时该大豆气吸式排种器排种性能最优,合格指数高达91.13%。该研究结果对排种器结构改进以及性能优化提供了参考依据。     

新型水土流失监测装置及其应用

测钎法是一种应用广泛的水土流失监测方法,但是传统测钎法难以适应复杂监测地形,缺乏专门测读装置,还会产生较大监测误差,需要对其加以改进.以颐和园万寿山山体为研究对象,针对其山体特征和文物分布状况,选定18块监测场地,发明单钎多点式测读装置,选用改进的测钎法对水土流失进行监测.结果表明:1)18块监测场地考虑了土壤、坡度、植被等因素的差异,可以全面反映万寿山水土流失状况;2)单钎多点式测读装置有效降低了测钎埋点环境条件、测读方式等客观和主观误差,提高了测钎法水土流失监测结果的准确性;3)监测期间,万寿山平均土壤流失值在-3 mm～ +1 mm范围内.说明新型水土流失监测装置是可行的,所用水土流失监测方法和数据处理方法,可供其他类似工程借鉴与应用.     

酸模叶蓼对大豆生长的影响及其经济阈值

酸模叶蓼是大豆田的恶性杂草,严重危害大豆生长发育及产量,为明确酸模叶蓼在大豆田中的经济危害允许水平和经济阈值,在大田条件下采用添加系列试验和拟合函数关系模型的方法,研究了酸模叶蓼与大豆的竞争关系。结果表明,在酸模叶蓼的竞争干扰下,大豆单株荚数,产量均随酸模叶蓼密度的增加而逐渐降低,而株高没有显著变化。线性函数模型y=-0.443x+39.453(R2=0.962,F=75.887,P=0.003)能较好地拟合酸模叶蓼对大豆单株荚数的影响;二次曲线函数模型y=0.702x~2-54.395x+3027.810(R~2=0.972,F=34.843,P=0.028)能较好地拟合大豆产量与酸模叶蓼密度之间的关系,对数函数y=16.131lnx-23.458(R2=0.911,F=20.532,P=0.045)能较好的拟合大豆产量损失与酸模叶蓼密度之间的关系。大豆田酸模叶蓼人工拔除的经济阈值为10.22株/m2,使用75%噻吩磺隆水分散粒剂、80%阔草清水分散粒剂、95%精异丙甲草胺乳油防除的经济阈值分别为4.75、5.03、5.25株/m~2。酸模叶蓼对大豆产量有明显影响,通过对经济阈值分析,在大豆田化学除草剂防治酸模叶蓼具有明显的经济优势。     

Agronomic traits of soybean cultivars released in different decades after grafting record‐yield cultivar as rootstock

Breeders have seldom considered the selection for root traits during the genetic improvement in soybean. It is hypothesized that grain yield would be increased by the root function improvement, especially for the current cultivars. The objective of this grafting experiment was to determine the effect of record‐yield cultivars L14 or Z35 as rootstocks on agronomic traits of cultivars released in different decades. A total of 11 cultivars, released in different decades, were used to graft onto L14 or Z35 rootstocks. The agronomic traits were measured in the pot‐culture experiments. Grafting cultivars released in different decades onto L14 or Z35 rootstocks resulted in higher yield, 100‐seed mass and apparent harvest index as compared with those of non‐grafted or self‐grafted plants. Grain yield gain of cultivars grafted onto record‐yield cultivar rootstocks was 0.40 g/plant/year from 1966 to 2006, which was larger than that of non‐grafts and self‐grafts (0.27 g/plant/year). The yield of current cultivars should increase more if their root functions were improved.     

Molecular mapping of soybean seed tocopherols in the cross ‘OAC Bayfield’ × ‘OAC Shire’

Soybean (Glycine max [L.] Merr.) is cultivated primarily for its protein and oil in the seed. In addition, soybean seeds contain nutraceutical compounds such as tocopherols (vitamin E), which are powerful antioxidants with health benefits. The objective of this study was to identify molecular markers linked to quantitative trait loci (QTL) that affect accumulation of soybean seed tocopherols. A recombinant inbred line (RIL) population derived from the cross ‘OAC Bayfield’ × ‘OAC Shire’ was grown in three locations over 2 years. A total of 151 SSR markers were polymorphic of which a one‐way analysis of variance identified 42 markers whereas composite interval mapping identified 26 markers linked to tocopherol QTL across 17 chromosomes. Individual QTL explained from 7% to 42% of the total phenotypic variation. Significant two‐locus epistatic interactions were identified for a total of 122 combinations in 2009 and 152 in 2010. The multiple‐locus models explained 18.4–72.2% of the total phenotypic variation. The reported QTL may be used in marker‐assisted selection (MAS) to develop high tocopherol soybean cultivars.     

Association analysis for detecting significant single nucleotide polymorphisms for phosphorus-deficiency tolerance at the seedling stage in soybean [Glycine max (L) Merr.]

Tolerance to low-phosphorus soil is a desirable trait in soybean cultivars. Previous quantitative trait locus (QTL) studies for phosphorus-deficiency tolerance were mainly derived from bi-parental segregating populations and few reports from natural population. The objective of this study was to detect QTLs that regulate phosphorus-deficiency tolerance in soybean using association mapping approach. Phosphorus-deficiency tolerance was evaluated according to five traits (plant shoot height, shoot dry weight, phosphorus concentration, phosphorus acquisition efficiency and use efficiency) comprising a conditional phenotype at the seedling stage. Association mapping of the conditional phenotype detected 19 SNPs including 13 SNPs that were significantly associated with the five traits across two years. A novel cluster of SNPs, including three SNPs that consistently showed significant effects over two years, that associated with more than one trait was detected on chromosome 3. All favorable alleles, which were determined based on the mean of conditional phenotypic values of each trait over the two years, could be pyramided into one cultivar through parental cross combination. The best three cross combinations were predicted with the aim of simultaneously improving phosphorus acquisition efficiency and use efficiency. These results will provide a thorough understanding of the genetic basis of phosphorus deficiency tolerance in soybean.     

Soil property differences among high‐ and average‐yielding soya bean areas in Arkansas,USA

Soya bean [Glycine max (L.) Merr] yields >6719 kg/ha (100 bu/ac) have only recently and infrequently been achieved. Quantifying soil property differences between high‐ and average‐yielding areas can help to further identify non‐plant‐related properties contributing to soya bean yield potential. The objective of this study was to evaluate the effects of region and soil depth on soil property differences between high‐ and average‐yielding areas. In each of the seven regions of the ‘Grow for the Green’ yield contest in Arkansas, prior to or just after harvest in 2014 and 2015, soil samples were collected from the top 20 cm of one contest high‐yield (HY ) area that was in close proximity to an average‐yield (AY ) area. Across all regions and both years, soya bean yields differed (P  <  0.05) between yield areas, averaging 4701 and 5498 kg/ha in AY and HY areas, respectively. Averaged across soil depth and years, numerous soil properties differed (P  <  0.05) between HY and AY areas within at least one of seven regions. Total soil C content was at least 20.2% greater in the HY than in the AY area in three of seven regions. Extractable soil P content was, on average, 19.4 kg/ha greater in HY than in AY areas in three of the seven regions. Results from this study have the potential to help producers better understand soil properties that contribute to or hinder achieving ultra‐high (>6719 kg/ha) soya bean yields.