马尔康县城区泥石流及其防治对策

本文根据作者1987年5月和8月两次对马尔康县城区泥石流实地考察的资料,对该区的4条泥石流沟的有关自然要素、灾害状况和潜在危险进行了分析研究,提出了对4条危害较严重的泥石流沟进行治理原则、方案和措施。     

做青环境调控方式对乌龙茶品质影响的试验研究

为了降低乌龙茶人工做青环境的投资成本和能耗，改善做青环境空气质量，对恒温恒风和恒温无风两种做青环境进行试验比较，通过在线测定做青环境指标及青叶若干生理指标，探明做青环境调控方式对叶层空气参数、青叶生理生化变化以及毛茶品质的影响。结果表明，恒温恒风调控方式能有效降低叶层空气的相对湿度，改善空气质量，增大青叶的气孔导度、失水速率及呼吸速率，提高毛茶的水浸出物和游离氨基酸含量，毛茶品质较优。春茶乌龙茶做青环境调控参数宜为：温度22～25℃，相对湿度70%～80%，做青前期叶层平均风速0.2 m/s。     

天山独─库公路三岔河道班泥石流沟成因分析

三岔河流域高山带裸露的岩石地表与其35°以上的陡峻地形一同构成了迅速汇流的有利条件;夏季高山带5℃～10℃左右的持续高温天气过程,引起冰舌末端发生冰体崩解或山缘积雪发生雪崩?进入沟道,并在较短时间内融化,形成激发泥石流的冰雪消融洪水?目前,由于提供泥石流的这种水源和沟道内丰富的松散固体物质条件依然具备,所以,泥石流爆发将仍处于活跃发展阶段?     

李家大沟泥石流与三峡库区奉节县新城建设

三峡库区奉节县新城建设大大改变了李家大沟中下游的地质环境,泥石流将直接威胁到新城区的建设和人民财产的安全。从工程地质角度出发,对李家大沟泥石流的形成环境(地层岩性条件、构造条件、地貌条件、气象条件、植被发育及人类工程活动)、基本特征(形成区和流通区特征)和形成机制进行了详细的系统研究,对泥石流的危害性和发展趋势做了预测评价,并提出了合理科学的建议。     

悬挂农具对电液悬挂系统拖拉机振动的影响

悬挂农具设备的拖拉机在行驶过程中的振动会加剧,有时甚至产生很大的俯仰运动。为了研究悬挂农具的存在对拖拉机振动特性的影响,该文在对拖拉机进行运动学和动力学分析的同时,首次详细分析了悬挂机构的运动及受力情况,从而建立了带有悬挂农具的大功率拖拉机整机振动数学模型;用Matlab仿真了拖拉机受到条形水泥障碍激励时的振动情况。研究表明:农具的存在使拖拉机前轮动载系数由O.26增大到0.55;空载拖拉机垂直振动频率为3 Hz,带农具的拖拉机垂直振动频率为2.5 Hz;农具的存在使得拖拉机的俯仰振动显著增加,频率为4.8 Hz;由于悬挂系统的运动与拖拉机机体振动的非线性耦合,一定条件下会表现出频率为10~15 Hz的第3振型的振动;农具的振动使得电液悬挂系统下拉杆铰接点处的力发生相应变化,其垂直分量的大小与农具质心垂直加速度之间存在较好的线性关系。仿真结果与试验结果相吻合,验证了所建数学模型的正确性。所得到的上述结论为拖拉机主动减振控制提供了理论依据。     

坡面侵蚀动力学及其相关参数的探讨

 从分析坡面水流形态动力学特性着手,对比土壤侵蚀临界坡度的研究;概述土壤侵蚀的机制,以及坡面水流中水流速度、泥沙含量和下垫面三者相互作用的关系。发现及时、准确和动态地测量水流速度和泥沙含量,是分析这些复杂关系的关键,它使定量研究坡面土壤侵蚀的机理成为可能。     

岷江上游某建设场地山洪泥石流灾害危险性分析

某建设场地位于岷江上游大沟流域,为山洪泥石流多发区。从主、支沟山洪泥石流特征、泥石流暴发规模及支沟泥石流对主沟山洪特征的影响等方面分析了场地可能遭受山洪泥石流灾害的危险性,并以此为基础对场地按危险程度进行了分区。结果表明,该场地主体位于基本无危险区,其建设计划是可行的。     

回转破碎气流干燥设备试验研究

介绍了回转破碎气流干燥设备的结构特点及其性能试验。该设备将滚筒破碎干燥机与气流干燥机串联组合，其组合衔接处采用封头板带过流孔的独特结构形式，把整个干燥过程分为三个阶段，集滚筒破碎干燥机、闪急干燥机和气流干燥机的优点于一体，提高了烘干效率和产品质量。     

RZWQM simulation of long-term crop production, water and nitrogen balances in Northeast Iowa

Agricultural system models are tools to represent and understand major processes and their interactions in agricultural systems. We used the Root Zone Water Quality Model (RZWQM) with 26 years of data from a study near Nashua, IA to evaluate year to year crop yield, water, and N balances. The model was calibrated using data from one 0.4 ha plot and evaluated by comparing simulated values with data from 29 of the 36 plots at the same research site (six were excluded). The dataset contains measured tile flow that varied considerably from plot to plot so we calibrated total tile flow amount by adjusting a lateral hydraulic gradient term for subsurface lateral flow below tiles for each plot. Keeping all other soil and plant parameters constant, RZWQM correctly simulated year to year variations in tile flow (r² = 0.74) and N loading in tile flow (r² = 0.71). Yearly crop yield variation was simulated with less satisfaction (r² = 0.52 for corn and r² = 0.37 for soybean) although the average yields were reasonably simulated. Root mean square errors (RMSE) for simulated soil water storage, water table, and annual tile flow were 3.0, 22.1, and 5.6 cm, respectively. These values were close to the average RMSE for the measured data between replicates (3.0, 22.4, and 5.7 cm, respectively). RMSE values for simulated annual N loading and residual soil N were 16.8 and 47.0 kg N ha⁻¹, respectively, which were much higher than the average RMSE for measurements among replicates (7.8 and 38.8 kg N ha⁻¹, respectively). The high RMSE for N simulation might be caused by high simulation errors in plant N uptake. Simulated corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] yields had high RMSE (1386 and 674 kg ha⁻¹) with coefficient of variations (CV) of 0.19 and 0.25, respectively. Further improvements were needed for better simulating plant N uptake and yield, but overall, results for annual tile flow and annual N loading in tile flow were acceptable.     

清水河流域泥石流成因分析及其防治对策

本文通过对影响该区土壤侵蚀的地质、地貌、气候、植被、土壤等自然因素和人类生产活动等因素的调查研究,分析了清水河流域泥石流发生的原因,并提出了防治对策。