基于质量反应法的拖拉机质心高度测量方法     

聂信天  史立新  顾浩  朱思洪 《农业工程学报》2011,27(13):336-339

根据拖拉机前后轮直径不相等的特点,提出了基于质量反应法的拖拉机质心高度测量方法,建立了拖拉机质心高度计算理论模型。与本文提出的方法相比较,发现两轴道路车辆质心高度测量标准中质心高度计算方法可作为其中的一个特例。以江苏常发集团生产的CF650型拖拉机质心高度测量为例,对该文所提出的测量方法进行了试验验证和误差分析。分析结果显示其最大相对误差为0.34%。结果表明该文提出的方法测量精度能满足工程要求。  相似文献   

中国农产品产地加工产业布局分析及发展对策   总被引：1，自引：2，他引：1  

朱明  沈瑾  孙洁  聂宇燕  杨琴  王希卓 《农业工程学报》2012,28(1):1-6

通过对大宗农产品的主要产地分布和大宗农产品加工业的产业布局进行分析,可推知中国大宗农产品产地初加工的格局已基本形成。农产品加工各行业的企业规模偏小、投资盲目、企业间无序竞争、精深加工的程度低、产品的附加值普遍不高等问题是制约中国农产品产地初加工产业化的问题所在。因此,应尽快实现中国农产品产地初加工由初级加工向高附加值精深加工转变,基本形成与国际接轨的农产品加工标准体系和全程质量控制体系,初步形成产学研相结合的研发机制和先进适用技术成果的推广体系,为农产品加工业健康快速发展奠定良好基础。  相似文献   

田块尺度土壤入渗特性空间变异研究   总被引：1，自引：4，他引：1  

聂卫波  武世亮  马孝义  费良军 《农业工程学报》2014,30(9):76-83

土壤入渗特性是田块尺度参数估值的重要基础。该文以陕西省杨凌区一级阶地砂壤土和三级阶地粘壤土所选典型田块的双环入渗试验为基础,分析了归一化因子在单一尺度和多尺度上的分形特征,并在此基础上建立了估算归一化因子的土壤转换函数。结果表明:对于修正Kostiakov公式所采用的归一化处理方法是可行的,可较好地预测典型田块各测点的土壤入渗过程;在单一尺度上,一级阶地和三级阶地所选典型田块的归一化因子最优半方差函数均为球状模型,其分形维数分别为1.796和1.840;在多尺度上,一级阶地典型田块归一化因子的空间变异受粉粒含量、砂粒含量和土壤容重的影响显著,三级阶地典型田块归一化因子的空间变异与黏粒含量、粉粒含量、砂粒含量和土壤初始含水率相关程度最高(显著性水平0.01);估算归一化因子的土壤转换函数具有较高的精度和可靠性,其一级阶地和三级阶地典型田块验证样本归一化因子的实测值与估算值相对误差绝对值均值分别为13.15%和9.95%。研究结果可较好地解决田块尺度内土壤入渗点面转换及入渗参数难以取得的问题。  相似文献   

Impacts of soil erosion on organic carbon and nutrient dynamics in an alpine grassland soil     

X.J. Nie  X.N. Qiao 《Soil Science and Plant Nutrition》2013,59(4):660-668

The impact of soil erosion on the nutrient dynamics in alpine grassland soils is still an essential problem. Selecting a grass-covered hillslope in eastern Tibet Plateau, the cesium-137 (¹³⁷Cs) technique was used to determine the impacts of soil erosion on soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), and total potassium (TK). The ¹³⁷Cs data revealed that there were distinct soil redistribution patterns in different hillslope positions because of the influences of slope runoff, plant coverage and grazing activity. For the upper slope, soil erosion first decreased downward, followed by soil deposition in its lower part. In contrast, for middle and toe slopes, there was an increasing soil erosion along a downslope transect. Across the lower slope, soil erosion showed an irregular variation. Influenced by the selective transport of water erosion, SOC, TN and TP storage decreased with increasing soil erosion in upper, middle and toe slopes. In contrast, SOC, TN and TP storage varied little with soil erosion in the lower slope. On the whole hillslope, TK storage also varied little with soil erosion due to the large amount of potassium elements derived from soil parent materials. Particularly noteworthy was the greatest storage of SOC, TN and TP in the lower slope where most obvious net soil erosion occurred, which is closely related to the humus accumulation combined with gravel separation as well as weathering and pedogenesis of parent rocks induced by soil freeze-thaw.  相似文献   

水土保持生态自然修复适宜性研究综述   总被引：2，自引：0，他引：2       下载免费PDF全文

聂斌斌  蔡强国  綦俊谕  崔普伟  陈晓安 《中国水土保持科学》2010,8(4):114-120

 根据我国的地域特点和水土保持生态建设的实施情况,进行适宜性研究至关重要。在介绍生态自然修复主要基础理论的基础上,分析了自然因素和人为因素对生态自然修复的影响作用。从区域定性、定量分析,地带性分区到GIS技术应用,以及适宜人为促进修复的作用和措施等方面探讨了水土保持生态自然修复适宜性研究的方法和内容。生态自然修复适宜性研究正向前迈进,在地理空间分析技术的引领下,生态自然修复适宜性评价在方法上会有新的发展。  相似文献   

水土保持综合治理效益评价研究进展   总被引：5，自引：0，他引：5  

聂碧娟  林敬兰  赵会贞 《亚热带水土保持》2009,21(3):39-41

随着时代的进步及人民生活水平的提高,水土保持工作受到广泛关注。政府不断加大对水土保持的投入,越来越多的水土保持生态建设工程项目启动实施,取得了显著的社会、经济和生态效益。水土保持综合治理效益评价是一项重要工作,本文论述了其指标体系的构建、指标权重的确定及其评价方法,对今后的研究发展提出了展望。  相似文献   

Characteristics of Nitrogen Loss through Surface-Subsurface Flow on Red Soil Slopes of Southeast China     

Haijin Zheng  Zhao Liu  Jichao Zuo  Lingyun Wang  Xiaofei Nie 《Eurasian Soil Science》2017,50(12):1506-1514

Soil nitrogen (N) loss related to surface flow and subsurface flow (including interflow and groundwater flow) from slope lands is a global issue. A lysimetric experiment with three types of land cover (grass cover, GC; litter cover, LC; and bare land, BL) were carried out on a red soil slope land in southeast China. Total Nitrogen (TN) loss through surface flow, interflow and groundwater flow was observed under 28 natural precipitation events from 2015 to 2016. TN concentrations from subsurface flow on BL and LC plots were, on average, 2.7–8.2 and 1.5–4.4 times greater than TN concentrations from surface flow, respectively; the average concentration of TN from subsurface flow on GC was about 36–56% of that recorded from surface flow. Surface flow, interflow and groundwater flow contributed 0–15, 2–9 and 76–96%, respectively, of loss load of TN. Compared with BL, GC and LC intercepted 83–86% of TN loss through surface runoff; GC intercepted 95% of TN loss through subsurface flow while TN loss through subsurface flow on LC is 2.3 times larger than that on BL. In conclusion, subsurface flow especially groundwater flow is the dominant hydrological rout for N loss that is usually underestimated. Grass cover has the high retention of N runoff loss while litter mulch will increase N leaching loss. These findings provide scientific support to control N runoff loss from the red soil slope lands by using suitable vegetation cover and mulching techniques.  相似文献   

黄瓜保鲜技术研究进展     

郑朕  聂小宝  李致瑜  丁天  张俊明  史君彦 《农产品加工．学刊》2011,(8):118-121

对黄瓜保鲜技术的理化、多糖及中草药贮藏方法进行了综述,提出了理化贮藏方法和中草药贮藏方法的不足,阐述了天然多糖在黄瓜保鲜中的应用,讨论了今后的主要研究方向。  相似文献   

农业机械化对农业产出的贡献率   总被引：2，自引：0，他引：2  

罗红旗  熊光洁  沈晓红  聂学俊 《农机化研究》2009,31(6)

测算出农业机械化对农业生产的贡献份额,有助于从总体上把握农业机械化的发展水平、发展潜力和发展趋势,为制定农业机械化政策提供可靠有力的理论依据.为此,分析了"有无比较"法及"生产函数"法应用于测算农业机械化贡献率的情况,并以湖南省为实例,采用"有无比较"法计算了农业机械化对农业产出的贡献率.  相似文献   

畦田Philip入渗参数和田面综合糙率同步推求   总被引：4，自引：1，他引：4  

聂卫波  马孝义 《农业机械学报》2009,40(5):39-44

以水量平衡原理为基础,通过对畦灌地表水面线的概化,并将Philip入渗公式等同为α=0.5的Kostiakov修正模型,由此建立了利用畦灌水流推进过程同步推求Philip土壤入渗参数和田面综合糙率的模型.结合文献资料和大田试验对所建模型进行验证,并采用Matlab软件求解,得出不同地表储水形状系数σh下的入渗参数和糙率,并分别对入渗参数和田面综合糙率的可靠性进行了验证,结果表明所建模型同步推求土壤入渗参数和田面综合糙率是可靠的,并且计算方便,精度较高.  相似文献