VERIFICATION OF MATHEMATICL MODEL FOR SEDIMENT TRANSPORT BY UNSTEADY FLOW IN THE LOWER YELLOW RIVER

Field data from the Lower Yellow River (LYR) covering a period often consecutive years are used to test a mathematical model for one dimensional sediment transport by unsteady flow developed previously by the writers. Data of the first year of the said period, i.e., 1976, are used to calibrate the model and those of the remaining years to verify it. Items investigated include discharge, water stage, rate of transport of suspended sediment and riverbed erosion/deposition. Comparisons between computed and observed data indicate that the proposed model may well simulate sediment transport in the LYR under conditions of unsteady flow with sufficient accuracy.     

DESIGN OF SEDIMENT TRANSPORTING CANAL SECTIONS

Design equations for minimum area or maximum velocity canal-sections for transport of bulk sediment carried by water have been obtained. Such canals are economically feasible in the terrain where large slopes are available. The design procedure is illustrated by a practical example.     

中国科学院院士、中国地质科学院地质研究所研究员沈其韩先生逝世

我国著名地质学家、中国科学院院士、中国地质科学院地质研究所研究员、中国地质学会32-33届理事、第37届常务理事、中国地质学会岩石专业委员会前主任委员沈其韩先生,因病医治无效,于2022年11月27日不幸逝世,享年100岁。中共中央委员、中国科学院院长兼党组书记侯建国同志受中共中央办公厅委托,向家属致电口头转达了习近平总书记对沈其韩院士逝世的悼念和对家属的慰问！同时,代表中国科学院学部、中国科学院党组,对沈其韩院士的去世表示哀悼,对家属表示慰问！第十九届中央政治局常委、国务院总理、党组书记李克强,中华人民共和国副主席王岐山,第十九届中央政治局委员、国务院副总理刘鹤,国务院前总理温家宝,第十八届中央政治局常委张德江,中央纪律检查委员会原书记吴官正,第二十届中央委员、国务委员、国务院秘书长肖捷对沈其韩同志的逝世表示哀悼和慰问。中共中央组织部办公厅请中国科学院转达了陈希同志和中共中央组织部领导对沈其韩院士的悼念和对家属的慰问！自然资源部部长王广华,中国地质调查局对沈其韩同志的逝世表示哀悼和慰问并送花圈。     

STUDY OF MORPHOLOGICAL CHANGE OF THE KUSHIYARA AND MONU RIVERS BY REMOTE SENSING

The Kushiyara and Monu rivers are two of the major river systems in the northeast region of Bangladesh. Analyzing satellite images of the Kushiyara and Monu rivers between 1990 and 1997, it was found that significant changes occurred at five distinct locations; i.e., Ahmadpur, Monumukh, Raysrr, Kaprangibari and Telibil. The amount of change was measured as 168.34 ha by using a plani-meter. Transportation of sediment was the major contributing factor of morphological change. The total average sediment concentration of Kushiyara and Monu rivers was found to be 16889.6 ppm per year during the study period by applying the Engelund and Hansen equation approach. Protection work has been suggested at the vulnerable locations.     

家庭送养的时空演化及决策机制

中国民间抱养行为由来已久,家庭送养的决策将完全改变儿童的生存和发展的轨迹。囿于送养的隐蔽性和复杂性,且相关研究匮乏,亟需系统性的剖析。文章基于公益平台寻亲数据,运用社会网络、空间分析、数理统计以及地理探测器的方法,探究1981—2010年家庭送养的时空分异特征,并进一步归纳送养决策的流程及原因机制。结果表明：1）送养主体为未满1周岁女童。2）送养人数在时间上呈现“先增后减”的倒“U”型分布,在空间上主要分布在中国东部、中部以及川渝地区。3）家庭送养原因以经济贫困为主,违反生育政策的影响次之。当家庭面临狭小的生育空间时,重男轻女的思想会被强化。4）地理探测器结果揭示,人口因素是影响送养空间分异最主要的原因,自然灾害、计划生育和经济因素在不同时期产生较大影响。5）基于理性选择理论提出了多尺度下的家庭送养的影响机制,认为家庭在作理性送养决策时,往往遵循生存理性、经济理性、制度理性以及社会理性的原则。     

天路奇观

青藏铁路是世界上海拔最高、线路最长的高原铁路,被誉为“天路”。它北起西宁,南至拉萨,全长1956公里,是中国20世纪四大工程（西气东输、西电东送、南水北调、青藏铁路）之一,也是西部大开发的标志。青藏铁路包括两段,北段西宁-格尔木,1979年动工,1984年投入运营,长达814公里。南段格尔木-拉萨,2001年6月动工,2007年7月投入运营,长达1142公里。