Influence of environmental, root, and stand parameters on soil surface CO₂ efflux in a Populus euphratica of desert forest in extreme arid region     

ZongQiang Chang  Qi Feng  YongHong Su  JianHua Si  HaiYang Xi  ShengKui Cao  Rui Guo 《寒旱区科学》2009,1(4):0348-0355

Spatial variation in soil surface CO2 efflux was measured in a stand of Populus euphratica in the Ejina Oasis of desert riparian forest in the extreme arid region in northwestern China from April 2007 through October 2007.Measurements were taken with a gas-exchange analyzer linked to a soil-respiration chamber.The mean soil CO2 efflux in the stand was 2.71 μmol/(m2·s) during the growing season and 1.38 μmol/(m2·s) in the nongrowing season.The seasonal maximum (end of May through early June) andminimum (October) CO2 efflux were 3.38 and 0.69 μmol/(m2·s),respectively.The diurnal fluctuation of CO2 efflux was relatively small (< 20 percent),with theminimum appearing around 05:00 and the maximum around 15:00.Linear regression analysis showed soil-surface CO2 efflux to be most highly correlated with soil temperature (R2=0.435) and soil moisture (R2=0.213).When all variables were considered simultaneously,only soil temperature (R2=0.378),soil moisture (R2=0.147),and root volume density (R2=0.021) explained a significant amount of variance in soil surface CO2 efflux.Stand volumes were not correlated with soil CO2 efflux on our sites.  相似文献   

AN EVALUATION OF SURFACE HARDNESS OF NATURAL AND MODIFIED ROCKS USING SCHMIDT HAMMER: STUDY FROM NORTHWESTERN HIMALAYA, INDIA     

BY VIKRAM GUPTA  RUCHIKA SHARMA  MADHO PRASAD SAH 《Geografiska Annaler: Series A, Physical Geography》2009,91(3):179-188

Four rock types (quartz mica gneiss, schist, quartzite and calc-silicate) located in the Satluj and Alaknanda valleys were used to test whether a Schmidt hammer can be used to distinguish rock surfaces affected by various natural and man-induced processes like manual smoothing of rock surfaces by grindstone, surface weathering, deep weathering, fluvial polishing and blasting during road construction. Surfaces polished by fluvial process yielded the highest Schmidt hammer rebound (R-) values and the blast-affected surfaces yielded the lowest R-values for the same rock type. Variations in R-value also reflect the degree of weathering of the rock surfaces. It has been further observed that, for all the rock types, the strength of relationship between R-values for the treated surfaces (manual smoothing of rock surface by grindstone) and the unconfined compressive strength (UCS) is higher than for the fresh natural surfaces.  相似文献   

KSC-127型射流式冲击器应用于大陆科学深钻的试验研究   总被引：21，自引：0，他引：21  

朴成哲  殷琨  蒋荣庆  王茂森 《世界地质》2000,19(3):295-298

根据现场试验,评价了ＫＳＣ－１２７冲击器的性能,分析了其对大陆科学深钻的适应性,且对大直径全面破碎冲击回转钻进工艺进行了讨论。  相似文献   

基于S波段双偏振雷达一次强雹暴过程观测分析     

吴福浪  李云  方艳莹  姜嘉俊 《气象科技》2023,51(2):245-253

利用宁波S波段双偏振天气雷达资料、NCEP再分析资料、结合常规观测资料和实地冰雹调查资料,对2020年3月21日浙江省中北部一次强雹暴灾害过程(简称“03·21”过程)的天气背景和双偏振雷达回波演变特征进行分析。结果表明：(1)此次雹暴过程环流形势属于低层暖平流强迫类型,雹暴影响过程约4 h,雹暴A和B先以强的对流单体形态移动,在自西向东移动过程中分别加强为超级单体。(2)典型降雹时次具有明显的三体散射特征(TBSS),垂直剖面图上强回波(>50 dBz)伸展高度超过-20℃层,低层的弱回波,中高层悬垂回波明显。径向速度垂直剖面图上,雹暴低层辐合,其上叠加了辐散层,使得雹块得以继续形成和增长。(3)冰雹区出现了Z_DR冰雹信号,对应的反射率因子(Z_H)均大于65 dBz,差分反射率因子(Z_DR)介于-2.0～0 dB,相关系数(C_C)介于0.80～0.98;当结合Z_H、Z_DR、C_C综合判断云中有冰雹粒子,C_C...  相似文献   

液动螺杆马达与潜孔锤复合钻具的研究     

陈宝义 《吉林大学学报(地球科学版)》1997,(2)

螺杆马达与潜孔锤同属孔底动力机，复合起来难度较大。通过时钻具参数匹配、钻具的连接方式及水功率的消耗等问题的分析，对复合钻具研究的理论方法进行了探讨，提出了适合于科学钻探的复合钻具的两种模式。为进一步研究奠定了基础  相似文献   

Classification of rock weathering at writing-on-stone Provincial Park,Alberta, Canada: A study in applied geomorphology     

Ian A. Campbell 《地球表面变化过程与地形》1991,16(8):701-711

At Writing-On-Stone Provincial Park in southern Alberta, Canada, weathering is causing deterioration and loss of archaeologically important Indian rock art. A procedure devised for the use of park personnel identified four classes of weathering ranging from largely unweathered rock to severely weathered. The technique employed simple visual, qualitative assessment and photo interpretation of 50 sample sections of sandstone cliff face covering a total area of 354 m². Schmidt hammer tests indicated large variations in rock strength and provided a numerical basis for the visual assessment. About 43 per cent of the cliffs are severely to completely weathered, 41 per cent show moderate weathering.  相似文献   

Use of the schmidt test hammer to detect enhanced boulder weathering under late-lying snowpatches     

Colin K. Ballantyne  Nicola M. Black  Donna P. Finlay 《地球表面变化过程与地形》1990,15(5):471-474

  相似文献   

Hammer's Impact Force on Pile and Pile's Penetration     

Ji-Cheng Wang  Jianlin Yu  Ma Shiguo  Xiaonan Gong 《Marine Georesources & Geotechnology》2016,34(5):409-419

Methods of energy and momentum conservation, vibration theories, and model tests are employed to research the impact force of a hammer on a pile and the pile's penetration. An analytical formula of impact force of the hammer on pile is obtained. A comparison of results from the three methods finds that the analytical formula proposed by this article conforms well to practical situations. Research results show that if the hammer's impact energy remains unchanged, penetration increases with the increase of hammer weight and cushion stiffness. In addition, the impact force received by the pile head degrades with the increase of hammer weight, but increases with the increase of cushion stiffness. Impact time decreases with the increase of cushion stiffness, but increases with the increase of hammer weight. The model test shows that, when compared with a cotton cloth cushion, an elastic cushion's advantages lie in that the relatively small pile head impact force can achieve significant pile penetration. The cotton cloth is gradually compacted with the increase of blow counts; hence, the impact force the pile head receives tends to increase gradually.  相似文献   

高能射流式液动锤在花岗岩中的钻进研究          下载免费PDF全文

孙强  杨冬冬  彭枧明  纪天坤  张鑫鑫 《探矿工程》2016,43(8):39-43

由于干热岩地层通常为火成岩,研磨性强、可钻性差,现有常规工艺方法钻进效率低,为此专门研制了用于干热岩钻进用的SC-86H型高能射流式液动锤,并对该高能射流式液动锤样机进行了地面钻进试验。试验采用可钻性等级为10级的完整花岗岩作为钻进对象,观测了冲锤质量、活塞行程和泵量对机械钻速的影响。试验结果表明：增大冲锤质量、活塞行程和泵量有利于提高机械钻速。试验过程中获得的最大机械钻速为5.19 m/h,较常规回转钻进机械钻速提升显著。  相似文献   

新型射流式元件结构设计与试验研究          下载免费PDF全文

纪天坤  孙强  杨冬冬  彭枧明 《探矿工程》2016,43(6):52-55

射流式液动锤由于其具有钻进效率高、钻进深度不受限制等优点被成功应用于油气钻井领域。然而由于射流元件在复杂受力条件下极易破损,严重制约了射流式液动锤的使用寿命。为解决此问题,对射流式液动锤射流元件受力情况进行了数值模拟分析,通过分析射流元件内部应力场分布情况,得出了射流元件破损机理,并设计了新型两体式射流元件。模拟分析研究表明,采用新型两体式射流元件可将元件内最大应力值降低一个数量级,使射流元件受力情况明显改善,可有效地提高其使用寿命。  相似文献