广州地区1984年6月小阵雨的微物理结构

本文分析了广州1984年小阵雨的雨滴谱分布。指出该地区小阵雨谱型以Ⅲ型谱(多峰谱)居多,不出现Ⅰ型谱(无峰谱)。滴浓度较小而平均尺度较大,最大滴直径达6.5mm。最突出的特点是起始直径较大,小滴明显不足而大滴较多,用指数谱描述不甚理想。 此外发现,W-I关系较Z-I关系的地区变异小得多;该地小阵雨的W-I,Z-I关系可分别表示为: W=0.0569I^(0.88), Z=345I^(1.39)。

海关总署关于废止《中华人民共和国海关关于异地加工贸易的管理办法》的决定

中华人民共和国海关总署令第234号《海关总署关于废止<中华人民共和国海关关于异地加工贸易的管理办法 >的决定》已于2017年11月20日经海关总署署务会议审议通过,现予公布,自公布之日起生效。

Evolution of Webcasting in Nigeria

This paper discusses the history and evolution of webcasting in the Federal Republic of Nigeria as a way of documenting an innovation, a process which thrived on existing system of broadcasting in the country. The paper premised on the webcast phenomenon as an offshoot of broadcasting. It begins by outlining the origins, history, and definitions of webcasting as a global phenomenon before linking these trends to the historical and contemporary context of Nigeria. Adopting the in-depth interview, the paper highlights the motivations for and advantages of using webcasting in Nigeria. It also provides prospects, challenges, and conclusions about the use of this technology within an African context. The paper posits that webcasting as an innovation has gained a firm hold among terrestrial broadcast outfits in the highly populated African country.

Determinants of Adoption of Agricultural Extension of Green River Project among Rural Households of Niger Delta, Nigeria

This study analyzed the determinants of adoption of agricultural extension of Green River Project among rural households of Niger Delta, Nigeria. Questionnaire, which was randomly distributed, was used for data collection from 270 direct beneficiaries of the project. Frequency, percentage and multiple regression were used for data analyses. For the beneficiaries, the results indicated a mean age of 48 years, 9 years of formal education, annual net farm income of N115, 681.48 and 2.8 times of monthly contact with Project Extension Officers. The mean adoption status of the project was 56.6%. The relationship between socio-economic characteristics of beneficiaries and adoption status gave an R2 of 0.668. Age, education, farming, experience, farm income and extension contact were significant determinants of adoption. The study recommends improvement in formal education, farm income, extension contact and inclusion of younger farmers as beneficiaries to enhance adoption status.

Estimating Soil Salinity in the Yellow River Delta, Eastern China——An Integrated Approach Using Spectral and Terrain Indices with the Generalized Additive Model

Soil salinity is one of the most severe environmental problems worldwide. It is necessary to develop a soil-salinity-estimation model to project the spatial distribution of soil salinity. The aims of this study were to use remote sensed images and digital elevation model(DEM) to develop quantitative models for estimating soil salinity and to investigate the influence of vegetation on soil salinity estimation. Digital bands of Landsat Thematic Mapper(TM) images, vegetation indices, and terrain indices were selected as predictive variables for the estimation. The generalized additive model(GAM) was used to analyze the quantitative relationship between soil salt content, spectral properties, and terrain indices. Akaike's information criterion(AIC) was used to select relevant predictive variables for fitted GAMs. A correlation analysis and root mean square error between predicted and observed soil salt contents were used to validate the fitted GAMs. A high ratio of explained deviance suggests that an integrated approach using spectral and terrain indices with GAM was practical and efficient for estimating soil salinity. The performance of the fitted GAMs varied with changes in vegetation cover.Salinity in sparsely vegetated areas was estimated better than in densely vegetated areas. Visible red and near-infrared bands, and the second and third components of the tasseled cap transformation were the most important spectral variables for the estimation. Variable combinations in the fitted GAMs and their contribution varied with changes in vegetation cover. The contribution of terrain indices was smaller than that of spectral indices, possibly due to the low spatial resolution of DEM. This research may provide some beneficial references for regional soil salinity estimation.

The Riemann Problem with Delta Data for Zero-Pressure Gas Dynamics

In this paper, the Riemann problem with delta initial data for the onedimensional system of conservation laws of mass, momentum and energy in zero-pressure gas dynamics is considered. Under the generalized Rankine-Hugoniot conditions and the entropy condition, we constructively obtained the global existence of generalized solutions which contains delta-shock. Moreover, the author obtains the stability of generalized solutions by making use of the perturbation of the initial data.