轻小型喷灌机组能耗计算与评价方法

为客观评价轻小型喷灌机组的能量消耗,应用水力机械能效计算基本方法,根据喷灌机组构成特点与运行特性,推导出喷灌机组与水泵的能耗计算公式,确定喷灌机组能耗评价指标与方法.借鉴多孔出流管道水力计算方法,采用退步法进行输水管道水力计算,应用迭代法求解喷头的流量和压力,提出喷灌机组水力计算步骤与方法.实例分析表明计算与评价方法简单实用、计算方便,进行喷灌机组能耗分析与评价具有可比性、可操作性和可靠性强的特点,计算与评价结果符合喷灌机组工程实际.研究结果能够为水泵的合理选型、管路装置优化配置与设计及喷灌机组产品的开发提供理论依据,对于提高喷灌机组装置效率、降低运行能耗,具有重要的理论意义和实用价值.     

双向竖井贯流泵进出水流道优化研究

基于RNG k-ε紊流模型和雷诺时均N-S方程,运用商用CFD软件对双向竖井贯流泵装置进行了三维流动数值仿真计算。对流道内的水力损失分析借鉴了微元法分析原理,通过对比分析分段水力损失可知:竖井作为进水流道时,其尾部汇合处水力损失较大,直管式出水流道在靠近导叶出口端水力损失较大,竖井作为出水流道在分叉处水力损失较大。通过调整竖井及直管式流道型线,有效减小水力损失,泵装置外特性有了较好的提升,最终完成水力性能优化设计。最终优化后的双向竖井贯流泵装置在叶片安放角为0°时数值计算结果正向运行效率最高达72.0%,反向为57.9%;模型试验结果正向运行效率最高达70.4%,反向为56.2%。     

基于动态规划法的金沟河流域农业水资源配置

为了提高金沟河流域枯水期水资源的利用效率,以流域灌溉效益最大为目标,建立需水量～灌溉效益数学模型,根据动态规划的原理和特点,利用软件Visial Basic编制计算程序对模型进行求解,使得灌溉效益模型计算较为简单,计算结果准确.通过计算与现状相比,金沟河流域3个灌区枯水期水资源得到了合理配置和利用,流域缺水量减少,灌溉...     

沙棘果采收后的管理及营养价值研究

沙棘(Hippopheae rhamnoides L.)是生长在高寒干旱地区的一种具有广阔开发前景的植物.因为它的药用价值,美容功效及保健作用,所以有很高的商业价值.这种小型的浆果极易腐坏,由于很酸所以不能在采摘后立即食用.因此,加工程序的研究是现在的当务之急,以确保能尽快地科学开发它的食用价值.1996年,印度Leh地区在实地研究实验室里首次完成了果实质量参数的评定、沙棘汁的提取和果实存储的研究.不同品种沙棘价值的合理利用技术将会标准化.     

大兴安岭北部西坡寒棕壤标准剖面的研究

在对大兴安岭北部林区寒棕壤进行多次面上调查及定位研究的基础上，根据初步拟定的“寒棕壤系统分类”，选择了具有广泛代表性的大兴安岭北部西坡潮查自然保护区作为寒棕壤标准剖面采集地点，并按“中国土壤系统分类研究项目”拟定的土壤剖面描述标准和土壤实验室分析项目及方法规范进行外业采集土壤标本和内业土壤分析。研究结果讨论了寒棕壤标准剖面的成土条件和基本性质；并以诊断层和诊断特性为基础研究检查了寒棕壤系统分类中的问题，对诊断层中的诊断表层（腐殖质表层、潜育特征），诊断表下层（风化Ｂ层、粘化层、灰化淀积层、灰化淀积特征）和诊断特性中的冻融特征、土壤水分状况、土壤温度状况、地表至５０ｃｍ土层的石砾含量等进行了检查讨论。     

火炬松种源木材化学成分的变异

报道了火炬松种源试验林木材主要化学成分含量的变异，方差分析表明火炬松种源间纤维素，木质素含量无显著性差异，戊聚糖，苯－醇抽出物含量则差异显著；木材主要化学成分含量广义遗传力较低，种源内株间木材化学成分含量变异大于种源间的差异。纤维素，木质素，苯－醇抽出物，戊聚糖含量与种源原产地地理气象因子间相关性不显著。     

Pathogenicity of Heterobasidion annosum (Fr.) Bref. sensu stricto on coniferous tree species in Turkey

Two‐year‐old seedlings of Pinus brutia, P. brutia var. eldarica, Pinus pinea and 3‐year‐old seedlings of Pinus radiata, Pinus sylvestris, Pinus nigra and Cedrus libani were inoculated on the lower stem with isolates of Heterobasidion annosum s.s. collected from the Black Sea and Mediterranean regions of Turkey. In total, 315 seedlings were inoculated in April 2014 and incubated in a growth chamber for 7 weeks at 18–20°C. All isolates were pathogenic on the seven different hosts and had the ability to grow in living sapwood. The isolates had a greater growth on C. libani, P. sylvestris and P. radiata seedlings compared to plants of the other species tested. The least affected species were P. brutia and P. nigra. The isolates originating from the Black Sea region caused longer lesions on the hosts. Overall mortality during 7 weeks of incubation was 4%.     

柳树杂种木材基本密度的遗传变异

利用柳属和钻天柳属种间、属间杂交１５个杂种３９个杂交组合１５１个无性系材料，对木材基本密度的遗传变异情况进行了研究。结果表明，杂种间和无性系间，在木材基本密度上存在极显著（α＝０．０１）差异，其中属间杂种（旱柳×钻天柳）×旱柳平均木材基本密度达到０．４８８，显著（α＝０．０５）超过各杂种平均值；柳树杂种及无性系木材基本密度是受强遗传控制的，被研究群体的广义遗传力达到０．９２￣０．９８，遗传变异系数     

Effect of six years of nitrogen additions on soil chemistry in a subtropical <Emphasis Type="Italic">Pleioblastus amarus</Emphasis> forest,Southwest China

Soil chemistry influences plant health and carbon storage in forest ecosystems. Increasing nitrogen (N) deposition has potential effect on soil chemistry. We studied N deposition effects on soil chemistry in subtropical Pleioblastus amarus bamboo forest ecosystems. An experiment with four N treatment levels (0, 50, 150, and 300 kg N ha^?1 a^?1, applied monthly, expressed as CK, LN, MN, HN, respectively) in three replicates. After 6 years of N additions, soil base cations, acid-forming cations, exchangeable acidity (EA), organic carbon fractions and nitrogen components were measured in all four seasons. The mean soil pH values in CK, LN, MN and HN were 4.71, 4.62, 4.71, and 4.40, respectively, with a significant difference between CK and HN. Nitrogen additions significantly increased soil exchangeable Al³⁺, EA, and Al/Ca, and exchangeable Al³⁺ in HN increased by 70% compared to CK. Soil base cations (Ca²⁺, Mg²⁺, K⁺, and Na⁺) did not respond to N additions. Nitrogen treatments significantly increased soil NO₃^?–N but had little effect on soil total nitrogen, particulate organic nitrogen, or NH₄⁺–N. Nitrogen additions did not affect soil total organic carbon, extractable dissolved organic carbon, incorporated organic carbon, or particulate organic carbon. This study suggests that increasing N deposition could increase soil NO₃^?–N, reduce soil pH, and increase mobilization of Al³⁺. These changes induced by N deposition can impede root grow and function, further may influence soil carbon storage and nutrient cycles in the future.     

退耕还林中经济林比重过高问题的探讨

退耕还林工作不仅关系到千家万户的当前收入和长远生计，还涉及农村经济结构调整、区域经济发展以及扶贫战略目标的实现等一系列重大问题，笔者仅就退耕还林工程中经济林过热问题作探讨，以保证退耕还林工作得以顺利进行。