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《寒旱区科学》2020年第3期中英双语摘要

已有 591 次阅读 2020-12-14 12:36 |系统分类:论文交流

 

0125−0133  A modified numerical model for moisture-salt transport in unsaturated sandy soil under evaporation … WeiWen, YuanMing Lai, ZheMinYou

Abstract:  Soil salinization, caused by salt migration and accumulation underneath the soil surface, will corrode structures. To analyze the moisture-salt migration and salt precipitation in soil under evaporation conditions, a mathematical model consisting of a series of theoretical equations is briefly presented. The filling effect of precipitated salts on tortuosity factor and evaporation rate are taken into account in relevant equations. Besides, a transition equation to link the solute transport equation before and after salt precipitation is proposed. Meanwhile, a new relative humidity equation deduced from Pitzer ions model is used to modify the vapor transport flux equation. The results show that the calculated values are in good agreement with the published experimental data, especially for the simulation of volume water content and evaporation rate of Toyoura sand, which confirm the reliability and applicability of the proposed model.

蒸发条件下非饱和砂土水盐迁移模型修正  文伟,赖远明,尤哲敏

干旱半干旱地区土体盐渍化现象非常普遍,盐分的存在容易对工程建筑物产生腐蚀性的影响。为分析蒸发条件下土体中的水盐迁移及盐结晶沉淀规律,以半经验半理论公式为基础推导得到了水盐迁移数学控制方程。在推导过程中通过考虑结晶沉淀盐对弯曲因子和土表面蒸发速率的影响,提出盐分结晶前后控制方程可自由转换的演化方程以及采用根据Pitzer离子模型推导得到的孔隙相对湿度式计算蒸汽迁移通量实现对水盐迁移控制方程的修正。通过将数值计算解与已发表文献的试验结果相比较可知计算结果与试验结果吻合程度高,尤其是与Toyoura砂的体积含水量和蒸发速率值的对比,从而验证了修正模型的可靠性与适用性。


0134–0143  Numerical simulations on cutting of frozen soil using HJC Model … WenQiang Zhang, YongHongNiu

 

Abstract: Numerical simulation is known as an effective method for mechanical properties during frozen soil excavation. In order to reveal the development of cutting force, effective stress and cutting fragments in frozen silt during the cutting process, we introduce an explicit finite element program LS-DYNA to establish a two-dimensional numerical model of the frozen soil cut. We also use the Holmquist-Johnson-Cook (HJC) damage constitutive model for simulating the variation of soil mechanical properties according to the strong dependence between the cutting tool and frozen silt during the process with different cutting depths, angles and velocities. Meanwhile, a series of experimental results are acquired of frozen silt cutting to prove the application of the HJC model during simulation of cutting force variations. The result shows that the cutting force and fragment size are strongly influenced by cutting depths and cutting velocities increased, and the maximum effective stress at points where the tool contacts frozen soil during the cutting process. In addition, when the cutting angle is 52°, the cutting force is the smallest, and the cutting angle is optimum. Thus, the prediction of frozen soil mechanical properties on the cutting process by this model is conducive to selecting machinery equipment in the field.

基于HJC模型的冻土切削数值模拟研究  张文强, 牛永红

数值模拟方法可简单有效地研究冻土切削过程中土体力学性能的变化。为了揭示冻结粉土在切削过程中切削力、有效应力和冻土切屑的变化规律,本文采用显式有限元程序LS-DYNA建立了冻土切削二维数值模型,并利用HJC损伤本构模型,模拟了冻土切削过程中不同切削深度、切削角和切削速率下刀具与冻土间的相互作用。对比相关冻结粉土切削试验,发现HJC模型在模拟冻土切削过程中切削力的变化具有较好的适用性。模拟结果表明,切削深度的增加和切削速率的增大强烈影响冻土切削力和切屑形态,发现最大有效应力位于刃尖附近;且当切削角达到52°时,切削力达到最小,认为该角度为最优切削角。因而,基于有限元程序的HJC模型,能够预测冻土切削开挖过程中土体力学性能的变化,有助于高效选取冻土开挖设备,节约开挖成本。


01440153  Mapping the dynamic degree of aeolian desertification in the Shiyang River Basin from 1975 to 2010 … Jie Liao, Tao Wang, ShaoXiu Ma, Jian Guo

Abstract: The Shiyang River Basin is an area of China that is severly affected by aeolian desertification. Thus, we established an Aeolian desertified land classification system for visual interpretation, which classified the Aeolian Desertified Land (ADL) into Slight (SL), Moderate (M), Severe (S) and Extremely Severe (ES) according to the severity. Imagery of Landsat series (acquired in 1975, 1990, 2000 and 2010) were employed to monitor the status, trend and spatial pattern of aeolian desertification, especially to map the overall spatial pattern of ADL dynamics by proposing a new Dynamic Index (DI) in the Shiyang River Basin from 1975 to 2010. The results show a generally decreasing trend from 1975 to 2010. However, the ES ADL kept increasing throughout the whole study period. Moreover, the area of ADLs with different severity increased with increasing severity, this S and ES ADLs dominated characteristics of aeolian desertification was contrary to those sandy lands in eastern China where was dominated by SL and M ADLs. Among the three sub-periods of 19751990, 19902000 and 20002010, the first two were the restoration stage, while the last one was the expansion stage of aeolian desertification. Moreover, all these new ADLs occurred in Minqin County during 20002010, indicating a detrimental increase of aeolian desertification in Minqin, and the concentration of ADLs toward the lower reaches of the Shiyang River Basin. The DI works well to identify areas with desertification changes no matter the sub-periods. Moreover, DI results disclosed a stable status of aeolian desertification, and the DI decreased with increasing ADL severity. These results indicate that it will be difficult to control the expansion of aeolian desertification in Minqin County over an extended period of time. Thus, we suggest effective and long-lasting aeolian desertification control programs in the Shiyang River Basin, especially in Minqin, and SL and MADLs should have priority in facilitating a quick reversal of aeolian desertification.

1975~2010年石羊河流域沙漠化动态变化分析  廖杰, 王涛, 马绍休, 郭坚

石羊河流域是我国受沙漠化影响最为严重的地区之一。基于地面和遥感影像特征分析而建立的沙漠化土地(ADL)分类系统,按沙漠化严重程度将沙漠化土地分为轻度(SL)、中度(M)、重度(S)和极重度(ES)四种类型。通过对Landsat系列影像的目视解译分析,获得了研究区1975年至2010年不同程度沙漠化土地时空动态变化数据,并提出利用动态指数(DI)来识别沙漠化土地变化的空间格局。研究结果表明,石羊河流域的沙漠化土地以重度和极重度为主,面积随沙漠化严重程度增加而增加,这与我国东部沙地以轻度和中度沙漠化土地为主明显不同;研究区沙漠化土地在1975年至2000年间为收缩趋势,在2000年至2010年间为扩张趋势,沙漠化土地面积在1975年至2010年间总体上呈下降趋势,但极重度沙漠化土地在该时段内持续增加。此外,2000年至2010年间新增的沙漠化土地几乎都出现在石羊河流域下游的民勤县,这表明石羊河流域的沙漠化土地有向下游集中的趋势。动态指数(DI)在识别不同时段内的沙漠化活跃区域有很好的效果,结果表明,动态指数DI随沙漠化严重程度的增加而降低。综合以上结果,民勤县沙漠化的扩张在较长一段时间内还将持续,因此,建议在石羊河流域特别是流域下游的民勤地区需要实施有效而持久的沙漠化治理方案,并优先实施轻度和中度沙漠化土地的治理,以促进沙漠化的快速逆转。


0154–0164  Quantitatively estimate the components of natural runoff and identify the impacting factors in a snow-fed river basin of China … Jia Qin, JinKui Wu, TianDing Han, QiuDong Zhao

 

Abstract: Snowmelt water is an essential runoff source of some alpine rivers in China. This study selected the Upper Burqin River (UBR), a typical snow-fed river, to quantitatively assess the runoff contributions of different components, as well as the causes of runoff variations under the background of cryosphere change and global warming. Based on the spatial-temporal distributions of snow and glaciers during a year, as well as the altitudinal variations of 0 °C isotherm, the high flow hydrographs in UBR was separated into two parts: seasonal snowmelt flood of lower altitudes (<3,000 m) and glacier-snow melt flow in high altitudes (3,0004,296 m). The daily baseflow hydrograph of UBR was separated by the digital filtering technique. It is concluded that the contributions of snowmelt flow, glacier melt flow, and baseflow (includes rainfall runoff component) to total annual flow volumes are 27.2% (±2.7%), 8.5% (±1.7%), and 64.3% (±3.0%), respectively. The speed of air temperature rise in spring may be the controlling factor for monthly snowmelt flow distributions in the snow-fed river. The volume of snowmelt was determined by spring precipitation (SP) and previous winter's precipitation (PWP). The PWP changes can explain 43.7% of snowmelt changes during 19812010 in UBR, while snowmelt change in 19571980 is more impacted by SP. The determining factor of snowmelt variation was changed from SP to PAP during the recent decades. Precipitation in current year, excluding previous year's rainfall and snowfall, can only explain 32%70% of the variability in total runoff.

高寒山区融雪补给类河流的径流分割及影响因子分析  秦甲,吴锦奎,韩添丁,赵求东

融雪水是中国诸多山区河流径流的重要补给源之一。本研究选择布尔津河上游为典型研究区,量化估算河流径流不同组成来源的年内变化,分析全球变暖、冰冻圈变化背景下的融雪补给类河流径流变化机理。研究基于流域冰川、积雪的年内时空分布,以及0 °C等温线所处海拔高度的年内变化特征,将布尔津河上游的夏半年洪水过程划分为两部分:低山区(<3,000 m)季节性融雪洪水以及高山区(3,000~4,296 m)冰雪融水径流。此外,河流的基流年内变化通过数字滤波法计算获得。通过分析得出结论:融雪径流、冰川融水以及基流(含降雨坡向流)分别占到流域总径流的27.2%±2.7%8.5%±1.7%)和64.3%±3.0%)。春季气温的上升速率是影响融雪径流年内分配的主控因素,而特定年的总融雪水量则由春季降水量以及前一个冬季的降雪量决定。布尔津河上游年均43.7%1981~2010)的融雪径流量由上一年的冬季降雪消融补给,而在1957~1980期间,年均融雪径流量主要受当年春季降水量影响。过去半个多世纪以来,布尔津河上游年内融雪径流量的主控因子由春季降水逐渐变化为前一年的降雪量。扣除前一年降水对当年流域径流变化影响,当年降水量仅决定了布尔津河上游年内总径流量32%~70%的变化。


0165–0179  A meta-analysis of the impacts of forest logging on soil CO2 efflux … LongFei Chen, YangZhou Xiang, ZhiBin He, Jun Du, PengFei Lin, Xi Zhu

 

Abstract: Soil CO2 efflux, the second largest flux in a forest carbon budget, plays an important role in global carbon cycling. Forest logging is expected to have large effects on soil CO2 efflux and carbon sequestration in forest ecosystems. However, a comprehensive understanding of soil CO2 efflux dynamics in response to forest logging remains elusive due to large variability in results obtained across individual studies. Here, we used a meta-analysis approach to synthesize the results of 77 individual field studies to determine the impacts of forest logging on soil CO2 efflux. Our results reveal that forest logging significantly stimulated soil CO2 efflux of the growing season by 5.02%. However, averaged across all studies, nonsignificant effect was detected following forest logging. The large variation among forest logging impacts was best explained by forest type, logging type, and time since logging. Soil CO2 efflux in coniferous forests exhibited a significant increase (4.38%) due to forest logging, while mixed and hardwood forests showed no significant change. Logging type also had a significant effect on soil CO2 efflux, with thinning increasing soil CO2 efflux by 12.05%, while clear-cutting decreasing soil CO2 efflux by 8.63%. The time since logging also had variable effects, with higher soil CO2 efflux for 2 years after logging, and lower for 3-6 years after logging; when exceeded 6 years, soil CO2 efflux increased. As significantly negative impacts of forest logging were detected on fine root biomass, the general positive effects on soil CO2 efflux can be explained by the accelerated decomposition of organic matter as a result of elevated soil temperature and organic substrate quality. Our results demonstrate that forest logging had potentially negative effects on carbon sequestration in forest ecosystems.

采伐对森林土壤呼吸影响的荟萃分析(Meta-analysis  陈龙飞,向仰州,何志斌,杜军,蔺鹏飞,朱喜

土壤呼吸是森林碳收支的第二大通量,在全球碳循环中起着重要作用。尽管在全球尺度上开展了大量相关的独立研究,但是目前关于采伐对森林土壤呼吸影响的一般规律认识仍然存在较大分歧。本研究对77篇已发表的文献资料进行了荟萃分析。结果表明,采伐后,虽然年均土壤呼吸速率没有显著变化,但是生长季土壤呼吸速率提高了5.02%。采伐对森林土壤呼吸的影响程度主要受到森林类型、采伐方式及采伐时间的影响:采伐显著提高了针叶林土壤呼吸速率(4.38%),但是对阔叶林和混交林土壤呼吸速率没有显著影响;间伐显著提高了土壤呼吸速率(12.05%),而皆伐显著降低了土壤呼吸速率(8.63%);随着采伐时间的延长,土壤呼吸速率呈现先增加(0~2年),后降低(3~6年),而后又增加(>6年)的趋势。由于采伐显著降低了细根(<2mm)的生物量,采伐后土壤呼吸速率的增加主要缘于土壤温度的增加以及可供微生物利用的有机活性底物质量的提高。研究发现,采伐对森林土壤的固碳能力有着潜在负效应。


0180–0188  Fast genetic mapping in barley: case studies of cuticle mutants using RNA-sequencing … XiaoFeng Li, Chao Li, Qin Zhou, GuoXiong Chen, PengShan Zhao

 

Abstract: Barley (Hordeum vulgare L.) is one of the earliest domesticated crop species and ranked as the fourth largest cereal production worldwide. Forward genetic studies in barley have greatly advanced plant genetics during the last century; however, most genes are identified by the conventional mapping method. Array genotyping and exome-capture sequencing have also been successfully used to target the causal mutation in barley populations, but these techniques are not widely adopted because of associated costs and partly due to the huge genome size of barley. This review summarizes three mapping cases of barley cuticle mutants in our laboratory with the help of RNA-sequencing. The causal mutations have been successfully identified for two of them and the target genes are located in the pericentromeric regions. Detailed information on the mapping-by-sequencing, mapping-and-sequencing, and RNA-sequencing assisted linkage mapping are presented and some limitations and challenges on the mapping assisted by RNA sequencing are also discussed. The alternative and elegant methods presented in this review may greatly accelerate forward genetics of barley mapping, especially for laboratories without large funding.

基于转录组测序的大麦遗传作图:以角质层相关突变体为例  李晓凤,李超,周琴,陈国雄,赵鹏善

大麦是人类最早驯化的农作物之一,在世界主要谷类作物中其产量排名第四位。上世纪大麦的正向遗传学研究显著促进了植物遗传学的发展,然而大部分基因是通过传统作图方式克隆获得的。基于基因芯片分型和外显子捕获测序的方法已被成功运用于大麦突变基因克隆,但是由于技术成本和大麦超大基因组等原因,这些技术并没有被广泛使用。本文以三个大麦角质层突变体为例,展示了利用转录组测序技术辅助定位和克隆相关目的基因的实验方法。其中,两个突变体的控制基因被成功克隆,另一个突变体的目标基因被定位于近着丝粒区域。本文详细阐述了测序定位、遗传作图联合测序分析,以及转录组测序辅助连锁图谱分析等三种方法的实验过程,并对转录组测序辅助遗传定位相关方法的局限性进行了探讨。这些非传统且简洁的方法将会快速推动大麦正向遗传学的研究,特别是对于一些没有充足研究经费的实验室,这个方法有着良好的适用性。



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