基于参变量扫值的非道路用柴油机增压匹配

为了解决传统增压匹配方法不能保证所选涡轮增压器与柴油机最佳匹配的问题,以及内燃机是高度的非线性系统,难以使用具体的数学公式来表示某一参数与其他参数之间的相互关系,基于一款非道路用柴油机的设计开发需求,提出了利用参变量扫值进行增压匹配的方法,以GT-Power软件为载体建立相应的增压柴油机模型,通过对不同大小的压气机和涡轮进行参变量扫值计算,在满足柴油机设计指标与耐久性约束的条件下,综合选取了与柴油机匹配良好的涡轮增压器。为了折中增压之后表征机械负荷的最高气缸压力与表征热负荷的排气歧管温度,又通过模拟分析确定了合理的增压压力和燃烧始点。台架试验结果表明:选定的涡轮增压器与柴油机匹配良好,各项性能参数与排放指标均达到了设计要求,合理匹配增压压力和燃烧始点可有效平衡最高气缸压力与排气歧管温度之间的矛盾。参变量扫值方法代替了实际增压匹配的复杂调整过程,并为实际的标定工作提供了一定的借鉴指导。     

几类图簇匹配等价图的结构性质

利用匹配多项式的代数性质,证明了几类图簇的匹配多项式因式分解理论,进而得到了这几类图簇匹配等价图的结构性质.     

基于直方图小波变换的图像颜色特征索引技术

提出了一种基于直方图小波变换的图像颜色特征索引技术:对图像HSV颜色直方图进行小波变 换,变换后数据用于相似性的递进匹配。该方法与直接直方图比较具有相同的效果,而特征矢量长度明 显减少,检索效率明显改进。实验结果表明,小波变换由于其金字塔形式可为图像数据库提供内容特征 的递进匹配,明显加快图像检索匹配速度。     

辽西河滩地杨树立地质量代换评价及适地适树的研究

本文采用数量化地位指数方法实现了小青杨、北京杨、小钻杨、健杨等辽西主要适宜杨树种类间的立地质量代换评价，建立了６对树种转换评价的配对方程。在此基础上进行了适地适树分析，将江西河滩地分为５个地力等级，分析了不同立地条件下各树种生长特性，在高地位质量条件下健杨生长最好，在中等立地条件下小钻杨为最优造林树种，在立地条件较差时小青杨、小叶杨较为适宜，北京杨则不作为辽西今后大力发展的树种。最后为不同地力等级内的各立地类型设计了最优造林树种和主要的改土培肥措施。     

Prediction of hydraulic conductivity and sorptivity in soils at steady-state infiltration

The purpose of this study was (1) to find a matching factor (u) between infiltration rate and hydraulic conductivity during steady-state infiltration, and (2) to propose equations based on infiltration and soil moisture-retention functions for prediction of the hydraulic conductivity K(θ) within the rapidly (non-capillary) drainable pores (RDP) and capillary-matrix pores of soils. The K(θ) of capillary pores was divided into K(θ)_SDP, K(θ)_WHP and K(θ)_FCP within slowly drainable pores (SDP), water-holding pores (WHP) and fine capillary pores (FCP), respectively. Five soil profiles of calcareous sandy loam, alluvial saline and non-saline clay, located at the Nile Delta, were used to apply the proposed equations. The highest and the lowest values of K(θ)_RDP were observed in calcareous and saline clay soil profiles, respectively. Values of K(θ)_RDP remained higher than those for capillary pores in the studied soils. The predicted values of K(θ) in capillary and non-capillary pores classes were in the expected range for unsaturated hydraulic conductivity. Water sorptivity (S) was determined at initial unsaturated soil water conditions and calculated at steady-state infiltration (S _w) using a derived equation. There was a decrease in S with an increase in soil water content; i.e. at steady-state infiltration, S decreased by 35–40% in calcareous soils and by 45–60% in alluvial clay soils. The parameter values of u and S _w tended to be uniform in calcareous soils, but nonuniform in saline and non-saline clay soils.     

卫星遥感影像的自动匹配

影像匹配是指在两幅或者多幅影像之间寻找同名像点的过程.它是从影像上自动提取地物三维空间信息的关键技术之一,已被广泛应用于摄影测量与遥感领域,如影像的自动内定向和立体像对的相对定向、摄影测量区域网平差中连接点的自动提取和DSM自动生成等.影像匹配结果的优劣直接影响后续遥感产品的质量.对于多重影像覆盖的区域或者基于控制点影像库的不同源遥感影像的联合处理,影像自动匹配技术就成为提高影像几何处理精度与作业效率的一项关键技术.该研究基于影像匹配的国内外研究成果,介绍了匹配中的图像预处理和基于控制点影像库匹配流程;并根据三线阵CCD影像的特点,介绍了基于金字塔分层动态窗口匹配运算的相关系数法在三线阵CCD影像像点立体匹配中的应用.     

Adoption of small-scale irrigation technologies and its impact on land productivity: Evidence from Rwanda

In an attempt to identify solutions to the effects of erratic rainfall patterns and droughts that limit agricultural production growth, the Rwandan government has recently increased investments in irrigation development. In this study, we analyze the adoption of small-scale irrigation technologies (SSITs) and its impact on land productivity using cross-sectional data from a sample of 360 farmers in Rwanda. The study uses the propensity score matching technique to address potential self-selection bias. Our results reveal that adoption decisions are significantly influenced by factors such as education, farm size, group membership, gender, extension services, access to credit, access to weather forecast information, risk perceptions, access to a reliable source of water for irrigation, awareness of rainwater harvesting techniques, and awareness of subsidy programs. In addition, the results show that the adoption of SSITs has a significantly positive impact on land productivity. The study concludes with policy implications that highlight the need to promote the adoption of SSITs among farmers as a strategy to improve agricultural productivity and food security in Rwanda.     

优质米加工及降碎措施

南方产优质稻谷粒形长,导致加工过程碎米率高、出米率低、生产成本高。实践表明,做好品种的选育、生产管理和收储,优化大米加工工艺流程及设备匹配,是降低优质米加工破碎率及提高经济效益的有效措施。     

谈西部生态建设的几个问题

在生态林规划中,应注意立地以水为主的生态负荷能力,使种植材料的生态习性与立地状况相适应.作好树种选择与树种搭配.扩大乡土树种、本地种源和灌木的种植比例,不要营造大面积纯林.在遗传改良品种的使用上,认为多无性系复合品种和实生繁殖材料,更有利于对本地环境的适应.     

板栗中毒死蜱农药残留检测结果满意度的研究

本文就如何保证农产品农药残留能力验证实验结果满意需要注意几个关键点进行探讨分析。要想通过板栗中毒死蜱农残的能力验证,样品前处理采用NY/T 761的方法,必须注意：提取液的过滤要用定性滤纸或脱脂棉,提取液过滤后静置时间控制在30 min～40 min之间,吸取10 mL乙腈液体要准确,净化步骤的水浴温度要严格按照方法要求,氮吹切记不要吹的太干,吹到潮乎乎为宜,SPE小柱的活化平衡要充分,上样时液面不能流干,上样后尽可能流干再洗脱,最后定容5.00 mL要准确。检测结束后,对结果进行验证很重要,可采用盲样的空白基质基质配标和空白基质基质加标画标准曲线两种办法。