国外早熟大豆冠层粒重分布与产量的关系

对国外早熟大豆冠层产量分布特点及冠层产量百分比与小区产量的相关性进行了研究。结果表明 :品种之间在产量空间分布的上层产量及下层产量存在显著差异 ,中层产量差异不显著 ;上层产量与小区产量呈显著正相关 ,下层产量与小区产量呈显著负相关 ,中层产量与小区产量无明显相关 ;在产量冠层结构中 ,上中层产量占全株产量比重较大的品种 。

两系法超级杂交稻粒重分布的差异

采用大田栽培方法,对两个大穗型两系超级杂交水稻培两优500和培两优E32稻穗上、中、下3个部位的平均籽粒重进行了研究。结果表明:稻穗上、中、下不同部位的平均粒重分布均呈正态性,不同部位间籽粒平均粒重方差齐性因品种自身充实程度而异,且稻穗上、中、下不同部位平均粒重均存在极显著差异。

茄子种高压电场分选的粒重分布试验与分析

茄子种落入高压静电场中 ,受到场强作用 ,将沿电场方向产生位移 ,不同场强作用 ,茄子种分离区会不同 ,不同分离区 ,种子的粒重也不相同 ,分布也不相同 ,它们之间存在着紧密相关作用 。

两系亚种间杂交稻粒重分布和结实特性研究

[目的]探讨亚种间杂交稻粒重分布特点和结实特性,为亚种间杂交稻组合的选育与高产栽培技术提供依据。[方法]以11个亚种间杂交稻组合为材料,开展两系亚种间杂交水稻粒重分布、结实特性及其差异分析。[结果]粒重分布和结实特性呈现一定的规律性,表现为穗上部总粒数较少,中下部较多,穗上部结实率较高,下部较低;穗上部的粒重较轻,下部较高。一次枝梗上的粒重较重,二次枝梗上粒重较轻,一次枝粳上籽粒优于二次枝粳上的籽粒;二次枝梗粒重占单穗粒重的比例大于一次枝梗。[结论]提高两系亚种间杂交稻栽培管理水平是必要的。一方面要构建合理的群体结构,加强水肥调控;另一方面要适期化控,改善营养物质的运输和分配。

Relationship Between Soil Properties and Different Fractions of Soil Hg

Correlation and path analysis methods were used to study the relationship between soil properties and the distribution of different soil Hg fractions with nine representative soils from Chongqing, China. Results showed that clay (< 2 m) could increase water-soluble Hg (r = 0.700*). Soil organic matter (OM) could enhance the increase of elemental Hg (r = 0.674*). The higher the base saturation percentage (BSP), the more the residual Hg (T = 0.684*). Organic Hg, the sum of acid-soluble organic Hg and alkali-soluble Hg, was positively affected by silt (2-20 μm) but negatively affected by pH, with the direct path coefficients amounting to 1.0487 and 0.5121, respectively. The positive effect of OM and negative effect of BSP on organic Hg were the most significant, with the direct path coefficients being 0.7614 and -0.8527, respectively. The indirect effect of clay (< 2 μm) via BSP (path coefficient = 0.4186) was the highest, showing that the real influencing factor in the effect of clay (< 2 μm) on acid-soluble organic Hg was BSP. Since the available Hg fraction, water-soluble Hg, was positively affected by soil clay content, and the quite immobile and not bioavailable residual Hg by soil BSP, suitable reduction of clay content and increase of BSP would be of much help to reduce the Hg availability and Hg activity in Hg-contaminated soils.

Origin of Quaternary Red Clay of Southern Anhui Province

The particle size distribution, heavy mineral constituents and rare earth elements (REE) characteristics of the Quaternary red clay of southern Anhui Province were studied to explore the origin of the clay. The results showed that the clay had some properties of areolian deposits, which could be compared with those of the loess in North China; and its chondrite normalized curves of REE were similar to those of the Xiashu loess, implying that they shared the same origin. It was concluded in combination with the results reported by other researchers that the Quaternary red clay of southern Anhui Province originated from aeolian deposits, and this could reveal the cycles of warm and cold climates in the area during the Quaternary period.

Development of a mass model in estimating weight-wise particle size distribution using digital image processing

Particle size distribution of coarse aggregates through mechanical sieving gives results in terms of cumu- lative mass percent. But digital image processing generated size distribution of particles, while being fast and accurate, is often expressed in terms of area function or number of particles. In this paper, a mass model is developed which converts the image obtained size distribution to mass-wise distribution, mak- ing it readily comparable to mechanical sieving data. The concept of weight/particle ratio is introduced for mass reconstruction from 2D images of particle aggregates. Using this mass model, the effects of several particle shape parameters （such as major axis, minor axis, and equivalent diameter） on sieve-size of the particles is studied. It is shown that the sieve-size of a particle strongly depend upon the shape param- eters, 91% of its variation being explained by major axis, minor axis, bounding box length and equivalent diameter. Furthermore, minor axis gives an overall accurate estimate of particle sieve-size, error in mean size （D-50） being just 0.4%. However, sieve-size of smaller particles （〈20 ram） strongly depends upon the length of the smaller arm of the bounding box enclosing them and sieve-sizes of larger particles （〉20 mm） are highly correlated to their equivalent diameters. Multiple linear regression analysis has been used to generate overall mass-wise particle size distribution, considering the influences of all these shape parameters on particle sieve-size. Multiple linear regression generated overall mass-wise particle size distribution shows a strong correlation with sieve generated data. The adjusted R-square value of the regression analysis is found to be 99 percent （w.r,t cumulative frequency）. The method proposed in this paper provides a time-efficient way of producing accurate （up to 99%） mass-wise PSD using digital image processing and it can be used effectively to renlace the mechanical sieving.

Resampling methods for particle filtering: identical distribution, a new method, and comparable study

Resampling is a critical procedure that is of both theoretical and practical significance for efficient implementation of the particle filter. To gain an insight of the resampling process and the filter, this paper contributes in three further respects as a sequel to the tutorial （Li et al., 2015）. First, identical distribution （ID） is established as a general principle for the resampling design, which requires the distribution of particles before and after resampling to be statistically identical. Three consistent met- rics including the （symmetrical） Kullback-Leibler divergence, Kolmogorov-Smimov statistic, and the sampling variance are introduced for assessment of the ID attribute of resampling, and a corresponding, qualitative ID analysis of representative resampling methods is given. Second, a novel resampling scheme that obtains the optimal ID attribute in the sense of minimum sampling variance is proposed. Third, more than a dozen typical resampling methods are compared via simulations in terms of sample size variation, sampling variance, computing speed, and estimation accuracy. These form a more comprehensive under- standing of the algorithm, providing solid guidelines for either selection of existing resampling methods or new implementations

Soil particle size distribution and its relationship with soil water and salt under mulched drip irrigation in Xinjiang of China

Soil particle size distribution(PSD),one of the most important soil physical attributes,is of great importance to soil water movement,soil erosion and soil solute migration.In this study,the soil PSD of 563 soil samples from the mulched drip irrigated cotton fields in Xinjiang of China were measured by laser diffraction particle size analyzer.The soil PSD characteristics and its relations with soil water and salt were studied by using the combined methods of textural triangle,fractal and multifractal analysis.The results showed very low clay content(about 1.52%) while really high sand content of the studied soil,and a complex shape of bimodal or unimodal of soil PSD.The results also showed that the two indices,i.e.,standard deviation and the peak value of soil particle relative volumes,were good indicators of soil PSD and thus had good relations with fractal and multifractal characteristics.The correlative analysis further indicated that the mulched drip irrigation had a significant impact on the distribution of the soil salt,while this impact withered for the deeper soil layer.The soil texture feature was found to dominate soil water and salt distribution,especially the surface soil salt content and the deep soil water content.

Single and Joint Multifractal Analysis of Soil Particle Size Distributions

It is noted that there has been little research to compare volume-based and number-based soil particle size distributions （PSDs）. Our objectives were to characterize the scaling properties and the possible connections between volume-based and number-based PSDs by applying single and joint multifractal analysis. Twelve soil samples were taken from selected sites in Northwest China and their PSDs were analyzed using laser diffractometry. The results indicated that the volume-based PSDs of all 12 samples and the number-based PSDs of 4 samples had multifractal scalings for moment order -6 〈 q 〈： 6. Some empirical relationships were identified between the extreme probability values, maximum probability （Pmax）, minimum probability （Pmin）, and Pmax/Pmin, and the multifractal indices, the difference and the ratio of generalized dimensions at q = 0 and 1 （Do - D1 and D1/Do）, maximum and minimum singularity strength （αmax and OZmin） and their difference （αmax - αmin, spectrum width）, and asymmetric index （RD）. An increase in Pmax generally resulted in corresponding increases of Do - D1, αmax, αmax - αmin, and RD, which indicated that a large Pmax increased the multifractality of a distribution. Joint multifractal analysis showed that there was significant correlation between the scaling indices of volume-based and number-based PSDs. The multifractality indices indicated that for a given soil, the volume-based PSD was more homogeneous than the number-based PSD, and more likely to display monofractal rather than multifractal scaling.