蒸汽喷射器的噪声控制方法研究

结合现场噪声测试结果,分析了蒸汽喷射器噪声的特点.在理论分析的基础上对蒸汽喷射器进行改进,并对其流场进行模拟.理论分析与模拟结果指出:由于喷嘴出口处轴线上垂直于轴线方向存在着很大的速度梯度,产生了很强的四极子声源,从而发射很强的噪声.改进后的喷射器投入工程使用后,经现场测试,降低噪声14dB.     

结构阻尼系统的一种子结构综合方法

本文对结构阻尼系统提出一种模态综合方法,该方法特别适合于部件对接界面自由度较少情况下的结构综合.给出了一个算例来说明方法的有效性.     

斜纹夜蛾性诱剂不同使用方法对诱蛾量的影响

通过对性诱剂及诱捕器不同悬挂使用方法对诱蛾量的影响进行应用观察研究,以期明确性诱剂诱捕器摆放高度、间距等较为合理的使用方法。试验结果表明,诱捕器在时间、气候条件等相同情况下,放置在作物顶端上方30~50 cm,诱蛾量最大;从节本和诱蛾效果来看,放置间距以50~80 m为宜;诱芯以单放为宜。     

不同播期、种植密度及整枝方式对黄秋葵产量的影响

为在甘肃庆阳地区推广种植黄秋葵,在塑料大棚内进行了4个播期(A)、2个种植密度(B)、2种整枝方式(C)对黄秋葵生长及产量影响的试验。试验结果表明,影响黄秋葵产量的关键因素是播期,其次是种植密度,整枝方式对产量影响不大,最优组合是A2B1C2,即播期3月30日、株行距30 cm×50 cm、不整枝,以及A1B1C1,即播期3月15日、株行距30 cm×50 cm、单秆整枝。     

Determination of the genetic variation in the effect of temperature and daylength on bolting of Brassica campestris L.

Summary Effects of temperature and daylength on the bolting of a number of B. campestris accessions were investigated both in the open and in the IVT phytotron. From the results it was concluded that low temperature and genotype are the predominant factors with respect to bolting. Daylength has rather limited influence. One cultivar bolted more than 12 weeks earlier at 10 and 14°C than at 18°C. On the other hand some cultivars did not require vernalization at all.At 14°C and short daylength, depending on genotype, the period of time between sowing and 50% bolting ranged from 8 to 30 weeks. At this temperature the stimulating effect of long day (24 h), depending again on the genotype, ranged from 0 to 4 weeks. The genotypes most resistant to bolting appeared to be the stubble turnips (B. campestris ssp. rapa).In terms of seed(ling) vernalization at 5°C the cold requirement ranged from 0 to more than 3 weeks, depending on the genotype. The required vernalization periods at 5°C can be used as a criterion in screening for resistance to bolting.     

毛细管气相色谱内标法测定防霉剂中富马酸二甲酯

建立了巴豆酸为内标物,用毛细管气相色谱快速测定防霉剂中富马酸二甲酯含量的方法.样品用乙酸乙酯提取,以DM-FFAP毛细管柱分离,火焰离子化检测器检测.结果表明,在0.25～3.0 mg/mL浓度范围内,富马酸二甲酯和巴豆酸的浓度比与峰面积比的回归方程为y=-0.0009 0.7174x,相关系数r=0.9996,检出限为5.0 mg/L;样品加标回收率(n=6)为97.0%～104.0%,相对标准偏差为3.26%.该方法简单、快速、准确度好,可用于测定防霉剂中的富马酸二甲酯含量.     

PAYING ATTENTION TO USE SIMPLEX METHOD FOR OPTIMAL MULTIPARAMETER IN THE DESIGN OF CONTROL SYSTEM

In the design of control system using simplex method for optimal multi-parameter,if the difference in number between the greatest and the smallestparameters is very great,the optimization process converges very slowly.Evenoptimal parameters can't be found at all.This paper studies the problem,analyses its cause and poses a resolution means.A testing example shows thatthis means can solve the above problem well.     

SOME PROBLEMS BY USE OF BOUNDARY POINT ELEMENT IN BOUNDARY ELEMENT METHOD

Using boundary point element is one of the treatmentsof corner node problem.This paper further discusses some problems byuse of point element.They mainly include the calculation of stresses atpoint elements,the cause and treatment of singularity in boundary usingequations when point elements are used.An example is given.Correctlyboundary point element has certain practical significance for moreobjective simulation of the actual situation of quantities and improvesaccuracy of results.     

Research on PDM Technology Oriented Dynamical Data

对冬枣采后主要病害种类、症状及防治方法进行阐述,并介绍了生物防治技术在果蔬贮运病害防治中的应用,展望了该技术在冬枣采后病害防治中的应用前景.     

凤仙花种子的贮藏特性研究

通过比较普通开放式贮藏、0~4℃冷冻贮藏和硅胶干燥贮藏条件下的凤仙花种子的活力和细胞膜完整性的变化,发现硅胶干燥贮藏能保持凤仙花种子较高的活力和细胞膜结构的完整性,是一种理想的贮藏方法。