Climate change and the future of freshwater resources of the island: a case study on the Rishiri Island,Japan

A comparison of the d-excess values of precipitation and of spring water, streams, groundwater wells and submarine groundwater discharge indicated that the precipitation that occurred during winter season was an important source of groundwater recharge. Due to the steep slope of the island, most of the short duration and high intensity precipitation is lost through direct surface runoff. The comparison indicated that snowmelt is an important resource of groundwater recharge on Rishiri Island. Future climate change will continue to diminish the snowpack, and therefore, reduce groundwater recharge. It may cause the decline of the groundwater level in the coastal area and possibly shift the saline–freshwater boundary on the island. Chloride data indicated that saltwater intrusion is beginning to occur on the western flank of the island. A Piper diagram shows that the water samples are characterized by the dominance of the Ca–HCO₃ and Na–Cl type. Their chemistry probably results from sea salt spray and the dissolution of minerals. These results support the need for the effective management of groundwater resources.     

长江经济带新型城镇化协调性的趋同与差异研究

近10年来,城镇化进程中暴露的很多问题可以归结为城镇化的协调性问题,本文以“人地关系”理论为基础,从城乡、产城、城镇化区域和城镇化与资源环境协调发展4个方面来衡量新型城镇化的协调性。并以长江经济带为研究区域,运用空间杜宾面板模型(spatial Durbin panel data model, SDPDM)从经验上考察新型城镇化协调性的俱乐部与条件趋同现象,发现制约长江经济带东、中、西部新型城镇化协调性的因素并不一致：东部城市应进一步加强城镇化同资源环境的协调,促进区域间的协同发展;中部城市应改变大拆大建的城市建设模式,着重发展服务业和增强城市间的合作;西部城市应进一步推进市场开放进程,减少政府对市场的干预和城市建设中的攀比,发展服务业和促进本地经济增长。同时,限制城市人口增长的政策对于新型城镇化协调性不存在显著影响,而放开户籍管制,则会促进人口向城市集聚;无论从促进第三产业发展、产城融合或是城乡协调发展,均会对新型城镇化协调性起到正向作用。     

不同破碎波对沙质海床作用的实验研究

破碎波对近海海岸地形以及海岸建筑物影响强烈,通过物理模型实验对孤立波、规则波作用下破碎带的床面形态以及孔隙水压力进行分析。破碎波冲击海床,破碎处床面上形成沙坝和沙坑,与规则波相比,孤立波破碎时对床面的冲刷更加剧烈,床面形成的沙坝和沙坑尺度更大,且土体内孔隙水压力幅值也较大。同时研究了波面变化对孔隙水压力的影响,发现波面变化历时曲线与孔隙水压力历时曲线相似,与孔隙水压力梯度历时曲线更为相似,说明波面变化更能反映海床内部孔隙水压力梯度的变化。通过探讨波浪与海床之间相互耦合作用,发现破碎带地形变化使得波浪出现不同破碎类型,分析得出卷破波比崩破波作用下孔隙水压力幅值大。     

梅雨与北极涛动及平流层环流异常的关联

平流层过程如何影响气候变化是一个大家关注的科学问题,在WCRP中专门设置了一个研究子计划SPARC.本文的分析研究表明,中国的梅雨异常可能受到平流层大气环流异常的影响,而这种影响是通过北极涛动（AO）的变化来实现的.从分析和计算结果可以看到,二月份北半球30 hPa位势高度的EOF第一主分量对应着副热带和高纬度地区的显著下传异常波作用量,其第三主分量对应着极地地区的显著下传异常波作用量,这些下传的异常波作用量都对三月份AO形势的形成有明显的贡献.三月份的AO则会通过影响东亚地区夏季对流层大气的冷暖状况和环流,在长江中下游地区导致异常垂直运动和辐散辐合形势,从而影响夏季的梅雨降水.     

基于特征向量法的地基红外高光谱反演大气温湿廓线附加影响因子分析

在地基高光谱遥感中,特征向量法获取的温湿廓线以初值的方式对物理反演进行约束,其反演精度对物理反演结果有着重要的影响。利用AERI的观测辐射资料和同站点的探空数据,基于特征向量法分析了温度廓线与湿度廓线反演的异同点;研究了主成分个数的选择问题,综合考虑反演精度和特征向量中包含的信息将反演温度廓线和湿度廓线的最优主成分个数定为7。为提高反演精度,引入地面温度、湿度、气压作为影响因子,试验结果表明,考虑反演精度和稳定性,地面气压的引入相比于其他2种单一气象要素以及3种气象要素组成的因子集表现更好,尤其是对边界层中下部的温湿廓线有着明显的提升,并随着高度的降低提升作用更明显,温度廓线RMSE降低最高达到1.5K,湿度廓线RMSE降低最高达到0.42g/kg。同时,分析了对数反演形式对湿度廓线的影响,结果表明,以水汽混合比的形式反演时取自然对数对反演精度的影响较小;将反演得到的水汽混合比转化为相对湿度后,取自然对数对反演精度有12%以上的提升。     

EM算法的BFGS和DFP联合加速算法

使用非线性规划中的变度量法BFGS算法和DFP算法给出了一种新的加速EM算法收敛的方法。     

A 3D discrete FEM iterative algorithm for solving the water pipe cooling problems of massive concrete structures

Water pipe cooling has been widely used for the temperature control and crack prevention of massive concrete structures such as high dams. Because both under‐cooling and over‐cooling may reduce the efficiency of crack prevention, or even lead to great harm to structures, we need an accurate and robust numerical tool for the prediction of cooling effect. Here, a 3D discrete FEM Iterative Algorithm is introduced, which can simulate the concrete temperature gradient near the pipes, as well as the water temperature rising along the pipes. On the basis of the heat balance between water and concrete, the whole temperature field of the problem can be computed exactly within a few iteration steps. Providing the pipe meshing tool for building the FE model, this algorithm can take account of the water pipe distribution, the variation of water flow, water temperature, and other factors, while the traditional equivalent algorithm based on semi‐theoretical solutions can only solve problems with constant water flow and water temperature. The validation and convergence are proved by comparing the simulated results and analytical solutions of two standard second‐stage cooling problems. Then, a practical concrete block with different cooling schemes is analyzed and the influences of cooling factors are investigated. In the end, detailed guidance for pipe system optimization is provided. Copyright © 2015 John Wiley & Sons, Ltd.     

Constraints on sedimentary ages of the Chuanlinggou Formation in the Ming Tombs,Beijing, North China Craton: LA-ICP-MS and SHRIMP U–Pb dating of detrital zircons

Detrital zircons in five sedimentary samples, MC1 to MC5, from the bottom of the Chuanlinggou Formation in the Ming Tombs District, Beijing, were dated with the LA-ICP-MS and SHRIMP U–Pb methods. Age spectra of the five samples show a major peak at 2500 Ma and a secondary peak at 2000 Ma, suggesting their provenances were mainly from the crystalline basement of the North China Craton and the Trans-North China Orogen. The youngest zircon has an age of 1673 ± 44 Ma, indicating that the Chuanlinggou Formation was deposited after this age. From sample MC4 to MC5, lithology changed from a clastic rock (fine-grained sandstone) to a carbonate rock (fine-grained dolomite), suggesting that the depositional basin became progressively deeper. The age spectrum of sample MC5 shows a major peak at 2500 Ma and a secondary peak at 2000 Ma. Sample MC4, which is stratigraphically lower than sample MC5, only had one peak at 2500 Ma. We conclude that there was a transgressive event when sediments represented by MC5 was deposited, and seawater carried ca. 2000 Ma clastic materials to the basin where the Chuanlinggou Formation was deposited, leading to the addition of ca. 2000 Ma detritus. Our research indicates that the source area for the sediments became more extensive with time. We conclude that the Chuanlinggou Formation in the Ming Tombs District was deposited in a low-energy mud flat sedimentary environment in the inter-supra tidal zone because it is mainly composed of silty mudstone and fine-grained sandstone with relatively simple sedimentary structures.     

复杂载荷作用下立管触地段损伤管道的动力响应

触地段(Touchdown zone, TDZ)是在役钢悬链线立管(Steel catenary riser, SCR)的关键部位,在复杂载荷作用下,极易形成损伤缺陷,其载荷寿命的评估是深海结构工程中的一个关键问题。本文以大型有限元软件ABAQUS为平台,运用损伤管道实体单元与土弹簧阻尼单元相互作用的模型模拟触地段损伤海底管道在复杂载荷作用下的动力响应,数值计算考虑了管-土相互作用过程中的材料非线性、几何非线性以及接触非线性。讨论了单一环向体积损伤位于触地段管道的不同位置时,触地段损伤管道在不同载荷作用下的动力特性及特征点的动力响应。结果表明,管道所受内外压力以及管道提升端的竖向位移载荷会影响结构的自振频率;体积损伤部位的动力响应较完好部位更剧烈;体积损伤的位置和动力载荷频率对管道动力放大系数的影响很大;当动力载荷的激励频率越接近结构基频时,损伤管道的动力响应及动力放大系数越大。     

准噶尔盆地周边硅质岩激光40Ar/39Ar法定年

由于较低的钾元素含量以及过剩氩的存在,长期以来对硅质岩的40Ar/39Ar定年一直存在较大难度。近年来,由于仪器水平的不断提高,新实验技术和方法的应用,特别是激光全熔40Ar/39Ar定年技术的应用,40Ar/39Ar定年方法具有了足够高的测试精度和稳定的低本底水平,可以满足测试极低钾元素含量的硅质岩样品的要求。利用多组矿物颗粒测试数据计算等时线年龄的方法可以很好地去除过剩氩对硅质岩年龄的影响。本文利用激光全熔40Ar/39Ar定年方法对新疆准噶尔盆地边缘的两个硅质岩样品进行了定年研究。采自白碱滩地区的08BJT-3样品的年龄测试结果为294±14Ma,该年龄结果与硅质岩样品所处的晚石炭世地层沉积年代基本一致。采自卡拉麦里地区的KML-2样品的年龄测试结果为266±14Ma,该年龄结果与强烈变形改造硅质岩样品的卡拉麦里构造变形带活动年代十分一致,表明激光全熔40Ar/39Ar定年方法可以准确地对硅质岩进行定年。