Demonstration and application of NMM‐based fractured porous medium flow model     

Qi‐Hua Zhang  Shao‐Zhong Lin  Hai‐Dong Su  Gen‐Hua Shi 《国际地质力学数值与分析法杂志》2021,45(1):132-153

In natural rock masses, the shapes of three‐dimensional (3‐D) blocks cut by arbitrary fracture networks may be very complex. Owing to the geometric complexity and difficulty of mesh discretization of 3‐D blocks and fracture facets, explicit consideration of fracture networks in flow analysis of fractured porous medium (FPM) is very challenging. Using the numerical manifold method based on independent covers (NMMIC), an FPM flow model was proposed that can deal with very complex 3‐D fracture networks. In this paper, the convergence of NMMIC was first demonstrated. The theoretical basis of the arbitrary refinement of computational meshes was proven. Moreover, three peculiarities of NMMIC meshes, that is, arbitrary shape, arbitrary connection, and arbitrary refinement of independent covers, were concluded. Finally, some two‐dimensional (2‐D) tunnel flow examples were analyzed and the numerical results were compared with the analytical results. 3‐D examples with complex fracture distributions were also analyzed. In addition, the computational scale of the developed program was tested by increasing the number of computational elements. The results show that our model can accurately analyze the groundwater flow of rocks surrounding tunnels with complex fracture distributions.  相似文献   

Estimation of genetic parameters for upper thermal tolerances and growth-related traits in turbot Scophthalmus maximus     

WANG Xin'an  MA Aijun  HUANG Zhihui  SUN Zhibin  CUI Wenxiao  QU Jiangbo  YU Hong 《中国海洋湖沼学报》2019,(5)

An abnormally high temperature produces a stress response in turbot causing large economic losses in the turbot aquaculture industry of China.A genetic improvement of the upper thermal tolerance(UTT)of turbot could allow cultured fish to adapt.A genetic evaluation of UTT is required for determining the practicability of including this trait into a breeding program.In this study,data were recorded from a temperature tolerance test conducted on 3 200 individual turbots from 32 full-sib groups.A cross-sectional linear model and a cross-sectional threshold probit model were used to analyze the test-period survival and a cross-sectional threshold logit model was used to analyze the test-day survival.In addition,phenotypic and genetic correlations between body weight and survival data were estimated.The estimated heritability values obtained from the cross-sectional linear model(CSL),the cross-sectional threshold(probit)model(THRp),and the cross-sectional threshold(logit)model(THR1)were 0.247 9±0.108 3,0.288 3±0.161 2,and 0.106 9±0.045 2,respectively.The correlation coefficients among the full-sib family estimated breeding values(EBVs)obtained from the three models were greater than 0.998 6 and all models produced an almost identical family ranking.The accuracies of selection obtained with the CSL,THRp,and THR1 model were0.773 8,0.775 4,and 0.784 4,respectively,the greatest from the THR1 model.The genetic correlations between body weight and survival data EBVs from the CSL,THRp,and THR1 models were 0.020 1,-6.201 1 ×10-4,and-3.115 4×10-4,respectively,and the phenotypic correlations between the two traits were-0.837 1 and-0.667 1,respectively.The findings of this study provide background information to determine the best strategy of selection for the genetic improvement of UTT in turbot.  相似文献   

COSI-Corr技术在风沙地貌研究中的初步应用及精度检验     

邵梅  罗万银  车雪华 《中国沙漠》2020,40(3):151-158

沙丘移动与形态监测是风沙地貌研究的重要内容，传统的测量方法对大范围的风沙地貌进行动态监测存在很大的困难。光学影像配准与关联（Co-registration of Optically Sensed Images and Correlation，COSI-Corr）技术的出现为区域风沙地貌的动态演化与监测研究提供了良好契机。讨论了COSI-Corr技术在沙丘移动和形态监测中的优势和存在的主要问题，通过无人机野外地面实测结果检验了COSI-Corr的测量精度。结果表明：沙丘背风坡底缘COSI-Corr测量精度最高，月测量误差0.01～0.53 m，达到影像分辨率的1/30像元；在沙丘背风坡底缘，COSI-Corr测量精度与沙丘底面积呈线性关系，底面积越大，COSI-Corr测量误差越大；个别沙丘脊线部位出现极大异常点，与沙丘脊线部位的光噪影响有关。COSI-Corr技术在风沙地貌监测中尚属起步阶段，一些具体的问题还需要我们在实践中不断的去检验和改进，但它确实极大提高了野外风沙地貌动态监测的效率，为研究大尺度范围内风沙地貌的时空动态演化过程提供了可能，在未来的风沙地貌研究中将具有广阔的应用前景。  相似文献   

Vertical distribution of sand layer CO<Subscript>2</Subscript> concentration and its diurnal variation rules in Alxa desert region,northwest China     

Tianjie Shao  Yandong Ma  Jingbo Zhao  Zhibo Dong  Liankai Zhang 《Environmental Earth Sciences》2016,75(18):1269

  相似文献   

黄海浒苔绿潮防灾减灾现状与早期防控展望   总被引：4，自引：2，他引：2  

王宗灵  傅明珠  周健  沈颂东  邵魁双  胡伟  肖洁  范士亮  张学雷 《海洋学报》2020,42(8):1-11

截至2019年，浒苔绿潮连续12年大规模暴发，对近海生态系统、沿岸环境与社会经济造成严重影响，已经成为黄海最严重的生态环境问题。本文总结了黄海浒苔绿潮防灾减灾现状与成效，分析了存在的问题，然后基于对该绿潮起源与成因的认识，将其早期分为3个关键过程，即浒苔微观繁殖体在养殖设施上的着生与生长过程，定生浒苔脱离附着基形成漂浮浒苔过程，浅滩漂浮浒苔进入深水区形成大面积绿潮过程。最后分别从加强新材料与技术研发防控绿藻着生、强化养殖设施回收管理严控定生绿藻落滩、浅滩汇聚通道拦截打捞等3种途径提出了早期防控措施建议，以期为黄海浒苔绿潮的源头防控提供科学依据。  相似文献   

Hydrological projections of future climate change over the source region of Yellow River and Yangtze River in the Tibetan Plateau: A comprehensive assessment by coupling RegCM4 and VIC model          下载免费PDF全文

Wenjun Lu  Weiguang Wang  Quanxi Shao  Zhongbo Yu  Zhenchun Hao  Wanqiu Xing  Bin Yong  Jinxing Li 《水文研究》2018,32(13):2096-2117

Understanding climate change impacts on hydrological regime and assessing future water supplies are essential to effective water resources management and planning, which is particularly true for the Tibetan Plateau (TP), one of the most vulnerable areas to climate change. In this study, future climate change in the TP was projected for 2041–2060 by a high‐resolution regional climate model, RegCM4, under 3 representative concentration pathways (RCPs): 2.6, 4.5, and 8.5. Response of all key hydrological elements, that is, evapotranspiration, surface run‐off, baseflow, and snowmelt, to future climate in 2 typical catchments, the source regions of Yellow and Yangtze rivers, was further investigated by the variable infiltration capacity microscale hydrological model incorporated with a 2‐layer energy balance snow model and a frozen soil/permafrost algorithm at a 0.25°×0.25° spatial scale. The results reveal that (a) spatial patterns of precipitation and temperature from RegCM4 agree fairly well with the data from China Meteorological Forcing Dataset, indicating that RegCM4 well reproduces historical climatic information and thus is reliable to support future projection; (b) precipitation increase by 0–70% and temperature rise by 1–4 °C would occur in the TP under 3 RCPs. A clear south‐eastern–north‐western spatial increasing gradient in precipitation would be seen. Besides, under RCP8.5, the peak increase in temperature would approach to 4 °C in spring and autumn in the east of the TP; (c) evapotranspiration would increase by 10–60% in 2 source regions due to the temperature rise, surface run‐off and baseflow in higher elevation region would experience larger increase dominantly due to the precipitation increase, and streamflow would display general increases by more than 3% and 5% in the source regions of Yellow and Yangtze rivers, respectively; (d) snowmelt contributes 11.1% and 16.2% to total run‐off in the source regions of Yellow and Yangtze rivers, respectively, during the baseline period. In the source region of Yangtze River, snowmelt run‐off would become more important with increase of 17.5% and 18.3%, respectively, under RCP2.6 and RCP4.5 but decrease of 15.0% under RCP8.5.  相似文献   

培育密度、换水量和倒池培育对珠母贝浮游幼虫生长发育和存活的影响   总被引：1，自引：0，他引：1  

黄海立  符韶  邓陈茂  刘志刚 《广东海洋大学学报》2010,30(1):50-54

以室内育苗池或玻璃缸养殖方式,研究了不同培育密度、换水量和倒池培育对珠母贝浮游幼虫生长发育和存活的影响。结果表明:当培育密度为0.8、1.2只/mL,直线铰合期时间分别为7.00、7.40d,日均生长为5.16、4.87μm,壳顶期时间分别为10.76d和10.77d,眼点期密度为0.58只·mL-1和0.60只·mL-1,差异不显著;日换水量分别为40%、60%、80%,直线铰合期时间、壳顶期时间、日均生长及眼点期密度差异不显著,日换水量40%能满足幼虫的生长和存活;壳顶初期进行倒池培育,能促进浮游幼虫的生长发育和提高其存活率。  相似文献   

地震数据采集器后级滤波器的设计     

邵玉平  宋澄  王翠芳 《地震地磁观测与研究》2010,31(5):108-113

以ADS1281为例,介绍新一代地震数据采集器后级滤波器设计。该后级滤波器包括变抽样率的梳状滤波器、有限脉冲响应(FIR1)4抽1滤波器和有限脉冲响应(FIR2)2抽1滤波器。其中,FIR1 4抽1滤波器和FIR2 2抽1又分为最小相位、线性相位和瞬态3种滤波器,文中使用设计的最小相位滤波抽取器对仿真的正弦波进行滤波验证,结果表明,通带波动和阻带衰减满足中国数字测震台网技术规程的要求。  相似文献   

Does Aqueous‐Phase Oxidation of HCHO Opens a Pathway to Formic Acids in Atmosphere?     

Xu Gang  Lee XinQing  Shao HongBo  Lv YingChun 《洁净——土壤、空气、水》2010,38(11):1006-1009

Formic acid is the major contributor to acid rain in some regions but its sources are not fully understood. We investigated the aqueous‐phase reactions of HCHO (aq) and OH ^. radicals at enlarged rainwater pH values (2.49–5.89) in Guiyang, China from May 2006 to April 2007. Our results show that there were no significant correlation between the [HCOOH]_t/[HCHO] (aq) and the rainwater pH. The ratio did not appear to vary consistently as a function of rainwater pH as predicted by theoretical model. In addition, we saw no clear evidence that oxidation of HCHO (aq) would produce significant HCOOH (aq) which indicates this reaction may be only a minor contribution to the budget of HCOOH (g) in atmosphere. Further investigation is strongly suggested to be carried out in field cloud water, fog water, or rainwater because the ratios would be diverged from equilibrium value as a result of other chemical or physical processes.  相似文献   

Effect of deposit alterations on the dating of herbivorous teeth from Arago cave by the ESR–U-series method     

F. Han  C. Falguères  J.-J. Bahain  Q. Shao  M. Duval  M. Lebon  T. Garcia  J.-M. Dolo  C. Perrenoud  G.J. Shen  H. de Lumley 《Quaternary Geochronology》2010,5(2-3):376-380

Geochemical alteration processes in archaeological sites may affect the environmental dose rate during the burial history and cause inaccuracy in age determination by palaeodosimetric dating methods, such as luminescence or ESR. In Arago Cave (Tautavel, France), the original composition of the sandy aeolian sediments of palaeoanthropological level G, where the Homo heidelbergensis Arago XXI skull was found, has been modified by both carbonation and phosphatization processes. Eight fossil teeth were collected from different geochemically affected parts of level G and analyzed by the ESR–U-series method. All the teeth are presumably contemporaneous. The results show that the samples from the phosphated area agree within error with those from the carbonated area. Surprisingly, the samples from the non-altered area show ages 100–150 ka younger. This difference is mainly due to the remarkable changes in the gamma dose rate over time. The measured in situ dose rate accounts for more than 50% of the total dose rate for all the samples. We observed that the samples' equivalent dose (D_E) were generally 20% lower in the non-altered area than in the carbonated and phosphated ones. These results show the crucial effect of the geochemical processes affecting the age calculation by ESR–U-series method in comparison with independent chronological data.  相似文献