冬季供暖工况下混凝土辐射顶板传热特性

针对冬季供暖工况下混凝土辐射顶板的传热问题,建立顶板辐射供暖的简化数学模型,利用MATLAB软件计算其供热量,并通过该顶板辐射供暖的热工特性实验验证模型的合理性。研究表明:顶板温度计算值与实验结果的误差在5.01%以内,供热量计算值与实验结果的误差在5.15%左右。通过对实验和计算结果的分析发现:在定流量稳态工况下,顶板温度随供水温度的增大呈指数性增大,随换热盘管间距的增大而减小。     

Tissue‐print and squash real‐time PCR for direct detection of ‘Candidatus Liberibacter’ species in citrus plants and psyllid vectors

Huanglongbing (HLB) disease is seriously threatening and/or damaging the citrus industry worldwide. Accurate detection of the three species associated with HLB disease, ‘Candidatus Liberibacter asiaticus’, ‘Candidatus Liberibacter africanus’ and ‘Candidatus Liberibacter americanus’, is essential for the preventive control of the disease. Real‐time PCR is a useful tool for bacterial detection. However, nucleic acid purification steps limit the number of samples that can be processed by PCR. Universal detection of ‘Ca. Liberibacter’ species was achieved by direct tissue‐printing and spotting of plant leaf petiole extracts or squashing of individual psyllids onto paper or nylon membranes. Primers were designed and used with TaqMan chemistry for accurate detection of the bacterium in immobilized targets (prints of 10 overlapping leaf pedicels per tree, or squashed single vectors), by extraction with water and direct use for real‐time PCR. This simplified method was validated and could detect HLB‐liberibacters in 100% of leaves with symptoms and 59% of symptomless leaves collected from HLB‐infected trees. The use of direct assays as template showed good agreement with use of purified DNA (κ = 0·76 ± 0·052). The squash assay allowed detection of the bacterium in 40% of mature Diaphorina citri that fed on leaves of HLB‐infected trees with or without symptoms. A commercial ready‐made kit based on this technology showed 96% accuracy in intra‐laboratory performance studies. The simplified direct methods of sample preparation presented herein can be effectively adopted for use in rapid screening of HLB agents in extensive surveys, certification schemes or for epidemiological and research studies.     

Parameter optimized Morlet wavelet de noising method based on cross validation method

A new de noising method based on parameter optimized Morlet wavelet is put forward. The Morlet wavelet is chosen as the mother wavelet because its shape is similar to the mechanical shock signals. The mother Morlet wavelet is improved by adding two parameters which decide the shape of the mother wavelet in time domain. The added parameters and the appropriate scale parameter for the wavelet transformation are designed by the cross validation method. Finally, the useful components of the signal can be obtained by the improved Morlet wavelet de noising method. The gear fault diagnosis experimental result shows that the proposed method has a good de nosing performance and it is effective in fault feature extraction.     

土壤水分过多对春玉米生长发育影响的模拟模型研究

运用ＰｅｎｎｉｎｇｄｅＶｒｉｅｓ研制的作物生长模型结合田间与水槽水分实验结果,建立了稻田玉米生长动态模拟模型。通过两年的实验验证,表明模型对稻田单作玉米的生育期、地上部茎叶干物质的动态及叶面积的变化的模拟与实测值较为一致,而对套作玉米的模拟则差异较大,需进一步考虑套作共生期内的麦／玉米之间的相互作用。文中还对模拟与实测值之间的差异进行了统计分析。     

土壤空间变异研究中的半方差问题

简要回顾了土壤空间变异的研究。根据地质统计学理论和多年从事土壤空间变异研究的经验,对土壤空间变异研究的关键问题——半方差函数的基本假设、取样、模型选取及模型的检验进行了讨论,并对确定半方差函数模型应注意的问题提出建议。在保证取样样本容量的前提下,检查测定数据是否服从内蕴假设;注意提高每一个估算值的置信水平;尽量选择安全型模型作为半方差函数模型;对确定的半方差模型进行统计检验。由此可以求得较为客观合理的半方差模型。     

小麦盐应答基因TaSR1的生物信息学鉴定及表达验证

为发掘小麦盐应答相关基因,利用Genevestigator在线生物信息学程序,分析了25个试验中118个样品的盐胁迫试验的转录组数据,筛选到2个盐应答候选基因。以中国春小麦为试验材料,将其三叶一心期幼苗根系置于200mmol·L~(-1)的NaCl溶液中,分别处理0、0.5、1、2、4和8h,分析候选基因的表达模式。结果表明,其中1个候选基因的表达模式与生物信息学分析结果相近,受盐胁迫诱导明显上调表达,命名为TaSR1。该基因编码区含有948个核苷酸,编码315个氨基酸。TaSR1蛋白含有KRTAP和PHA01732两个保守结构域,富含脯氨酸残基。     

MODIS/FAPAR在呼伦贝尔草原区的精度验证与分析

验证MODIS/FAPAR产品在温性草原地区的精度，以提高NPP估算精度，为区域碳平衡监测及合理安排草地畜牧业生产提供服务。该文选取两块2 km×2 km温性草甸类草地设计和进行FAPAR实测试验。以分辨率为32 m的北 京-1号卫星遥感数据对样地进行异质性分析，然后进行尺度上推，利用地面实测数据对1km的MODIS/FAPAR草原地区产品进行验证。结果表明，在草地生长季，MODIS/FAPAR产品的草地FAPAR季节变化与实测FAPAR季节变化趋势基本一致，但总体要比实测FAPAR要高，针茅样地MODIS/FAPAR值比实测值要高约13.7%，羊草样地为18.7%。MODIS/FAPAR算法对于局部区域过于粗糙，对草地类型多样的中国来说，需更多的野外试验资料，以反演适合不同草地类型的FAPAR算法。     

喷嘴空化模型建立与有效性试验验证

提出了一种针对喷嘴孔内空化现象的数值计算模型——喷嘴空化模型,并进行了可视化试验以验证其模型有效性,其中喷嘴空化模型考虑了液相与气相之间相变、气泡动力学、湍流扰动及不凝性气体影响等诸多因素,并采用喷孔内空化数对相变速率方程进行了修正。将基于喷嘴空化模型的数值计算结果与试验结果及基于Schnerr-Sauer模型的计算结果进行对比分析,结果显示:在2种空化模均采用默认参数的前提下,喷嘴空化模型与Schnerr-Sauer模型计算所得喷孔内空化现象变化趋势均与试验结果吻合良好,即喷嘴孔内空化现象随喷射压力提高而加强,且在发展空化至超空化流态过渡过程中空化特征长度涨幅远高于其他流态过渡情况;喷嘴空化模型计算所得空化特征长度在各流态下均与试验结果吻合良好,Schnerr-Sauer模型计算空化特征长度则低于试验结果,两者与试验值的最大误差均发生在超空化阶段,其中喷嘴空化模型计算值为试验值的92%,Schnerr-Sauer模型计算值为试验值的65%。该结果表明,所建立喷嘴空化模型可用于较为准确地模拟喷嘴孔内空化现象的变化趋势及空化特征长度。     

车辆传动系统虚拟样机建模与验证

为实现在设计阶段对车辆传动系统性能进行预测,以目前广泛应用的液力机械传动系统的组成和工作原理为基础,提出了可闭锁式液力变矩器和换挡离合器两个关键部件级,以及整个系统级虚拟样机建模方法,并进一步分析建立了相对应的数学模型。以起步工况试验的动力输入特性和操纵方式作为模型的输入条件对其进行了验证。通过仿真与试验测试结果对比,表明所建立的模型正确、合理并具有较高的精度。