专业学位研究生“油藏工程设计”课程教学研究

针对目前"油藏工程设计"实践性不强、学生主动参与程度不高和工程设计培养能力不全的问题,通过优化教学内容,建立油藏工程设计案例资源库和教学平台,实现"理论学习、案例实训、系统实践"三位一体的以实践训练为主和理论教学为辅的混合式教学模式,形成了适合于石油与天然气工程专业学位研究生工程实践能力培养的核心课程内容体系和教学模式。

专业学位研究生油藏工程设计混合式实践教学模式探索

实践性教学是专业学位研究生教育的重要组成部分,是实现人才培养目标的重要教学环节。本文围绕专业学位研究生课程建设和教学模式的相关要求,结合"油藏工程设计方法与应用"课程实际情况,充分利用现代信息技术,优化组合各种教学要素,探索了线上与线下、课堂与实训、院校教师与行业专家相结合的油藏工程设计混合式实践教学模式。

林业院校本科毕业论文常见问题分析及改进措施

本科生招生规模的扩大及师资队伍建设滞后等原因,导致本科毕业论文质量严重下滑。针对本科毕业论文在选题、摘要、绪论、实验材料和方法、实验结果、讨论和结论内容中出现的问题进行分析,并提出合理建议和改进措施,以期为提高林业院校本科毕业论文质量提供新思路。

林业院校本科毕业论文现状调查分析与策略——以生命科学与技术学院为例

本科毕业论文是本科教学工作中的重要环节,是评价学生综合能力和高校教学质量的重要指标。招生规模扩大、教学设施建设滞后等,导致本科毕业论文质量严重下降。鉴于此,以湖南省长沙市某林业院校生命科学与技术学院2018届毕业生为研究对象,以电子调查问卷和访谈的形式,从专业兴趣、毕业论文的形成与选取、文献的获取与质量要求、毕业论文形成中的困难与解决方式和完成毕业论文的目的和时间投入5个方面对毕业论文的现状进行调查与分析,并提出改进措施与策略,以期为提高林业院校本科毕业论文质量提供新思路。

广西猫儿山国家级自然保护区森林生态系统生态服务价值评估

按照《森林生态系统服务功能评估规范》要求,基于猫儿山国家级自然保护区森林资源调查、野外观测研究和当地社会经济发展数据,评价保护区森林生态系统生态服务价值。结果表明:(1)2014年保护区森林生态系统生态服务总价值为165 557.736万元·a-1,单位面积森林生态系统生态服务价值为10.802万元·hm-2·a-1。(2)保护区森林生态系统生态服务价值从大到小依次为:涵养水源、生物多样性保护、固碳释氧、净化大气环境、保育土壤、森林游憩、积累营养物质,其中涵养水源占总价值量的58.35%,生物多样性保护价值占总价值量的17.27%。(3)保护区典型森林生态系统生态服务总价值从大到小依次为:阔叶林、灌木林、马尾松林、杉木林、毛竹林,单位面积森林生态系统提供的生态服务价值排序不同于总价值,毛竹林最大。说明相同面积的森林生态系统生态服务价值受到系统结构和活力等因素的影响,表现出较大的差异。

Effects of Thinning and Litter Fall Removal on Fine Root Production and Soil Organic Carbon Content in Masson Pine Plantations

Soils play a critical role in the global carbon cycle, and can be major source or sink of CO2 depending upon land use, vegetation type and soil management practices. Fine roots are important component of a forest ecosystem in terms of water and nutrient uptake. In this study the effects of thinning and litter fall removal on fine root production and soil organic carbon content were examined in 20-year-old Masson pine (Pinus resinosa) plantations in Huitong, Hunan Province of China in the growing seasons of 2004 and 2005. The results showed that fine root production was significantly lower in the thinning plots than in the control plots, with a decrease of 58% and 14% in 2004 and 2005 growing seasons, respectively. Litter fall removal significantly increased fine root production by 14% in 2004. Soil temperature (Tsoil) and soil moisture (Msoil) were higher in the thinning plots than those in the controls. Litter fall removal had significant effiects on Tsoil and Msoil. Soil organic carbon content was higher in the thinning plots but was lower in the plots with litter fall removal compared with that in the controls. Our results also indicated that annual production of fine roots resulted in small carbon accumulation in the upper layers of the soil, and removal of tree by thinning resulted in a significant increase of carbon storage in Masson pine plantations.

垂直管中气-水-泡沫三相管流空隙率实验研究

空隙率是计算气-水-泡沫三相管流压力、温度的重要参数,准确预测气井中气-水-泡沫三相管流空隙率对泡沫排水采气工艺技术的高效实施及方案优化至关重要。目前关于气-水两相管流空隙率模型研究较多,而气-水-泡沫空隙率研究相对薄弱。因此通过开展气-水-泡沫三相空隙率测量实验,研究了泡排剂浓度、气量、液量对空隙率大小的影响规律。基于漂移模型,考虑泡排剂浓度、气液表观流速、密度、滑脱速度等参数,建立了适用于垂直管的气-水-泡沫三相管流空隙率模型,并分别利用145组实验数据和602组文献数据验证了模型的准确度。结果表明,预测实验数据时平均相对误差为2.24%,平均绝对误差为2.47%;预测文献时平均相对误差为-4.65%,平均绝对误差为6.21%;证明新模型计算精度较高,可满足工程需求。新模型可为泡沫排水采气工艺技术的高效实施和方案优化提供理论指导。

控水条件下侧柏冠层气孔导度对土壤水的响应

建立了不同控水条件下(无降水、一半降水、自然降水和二倍降水)的侧柏样地,于2016年8月—2017年8月监测了样地土壤含水量(SWC)、降水量、液流密度(Js)、叶面积指数(LAI)和水汽压亏缺(VPD)等因子,分析SWC对侧柏冠层气孔导度(gs)的影响。结果表明:一半、自然和二倍降水样地的SWC与降水量呈正相关,SWC变化范围分别为4.9%~16.0%、7.2%~22.9%、7.4%~29.6%,无降水样地的SWC在8—10月下降50%;7月的日gs在14:00达到峰值(166.64 mmol·m-2·s-1),显著高于其他月份,且出现双峰现象,1月的日gs在12:00达到峰值(54.1 mmol·m-2·s-1);3个降水条件下,侧柏gs与SWC呈负二次相关关系,且gs达到峰值,对应的SWC分别为8.5%、12.5%和18.5%,均趋近于年平均SWC。不同控水样地内侧柏gs对VPD的敏感性(δ)/参比冠层气孔导度(gsref)均≥0.6,表明不同控水条件下土壤水分状况较适合侧柏蒸腾用水的需求。当SWC在3.7%~7.5%时,δ和gsref值迅速增大,说明气孔调节能力更好,植物气孔对VPD的响应更敏感;当SWC上升到11%时,SWC变化对gsref和gs对VPD响应敏感性的影响不显著。可能存在侧柏产生适应状态的SWC阈值,植物体在自身的生命活动中关闭或减小气孔开度,降低叶片水势以适应过高的VPD,保护植物不会引起过度蒸腾,从而对蒸腾的调控更加有效。

Soil CO_2 Flux in Different Types of Forests Under a Subtropical Microclimatic Environment

The flux of carbon dioxide(CO2) from soil surface presents an important component of carbon(C) cycle in terrestrial ecosystems and is controlled by a number of biotic and abiotic factors. In order to better understand characteristics of soil CO2 flux(FCO2) in subtropical forests,soil FCO2 rates were quantified in five adjacent forest types(camphor tree forest,Masson pine forest,mixed camphor tree and Masson pine forest,Chinese sweet gum forest,and slash pine forest) at the Tianjiling National Park in Changsha,Hunan Province,in subtropical China,from January to December 2010. The influences of soil temperature(Tsoil),volumetric soil water content(θsoil),soil pH,soil organic carbon(SOC) and soil C/nitrogen(N) ratio on soil FCO2 rates were also investigated. The annual mean soil FCO2 rate varied with the forest types. The soil FCO2 rate was the highest in the camphor tree forest(3.53 ± 0.51 μmol m-2s-1),followed by,in order,the mixed,Masson pine,Chinese sweet gum,and slash pine forests(1.53 ± 0.25 μmol m-2 s1). Soil FCO2 rates from the five forest types followed a similar seasonal pattern with the maximum values occurring in summer(July and August) and the minimum values during winter(December and January). Soil FCO2 rates were correlated to Tsoiland θsoil,but the relationships were only significant for Tsoil. No correlations were found between soil FCO2 rates and other selected soil properties,such as soil pH,SOC,and C/N ratio,in the examined forest types. Our results indicated that soil FCO2 rates were much higher in the evergreen broadleaved forest than coniferous forest under the same microclimatic environment in the study region.