An Overview of Existing Algorithms for Resolving the 180° Ambiguity in Vector Magnetic Fields: Quantitative Tests with Synthetic Data

We report here on the present state-of-the-art in algorithms used for resolving the 180° ambiguity in solar vector magnetic field measurements. With present observations and techniques, some assumption must be made about the solar magnetic field in order to resolve this ambiguity. Our focus is the application of numerous existing algorithms to test data for which the correct answer is known. In this context, we compare the algorithms quantitatively and seek to understand where each succeeds, where it fails, and why. We have considered five basic approaches: comparing the observed field to a reference field or direction, minimizing the vertical gradient of the magnetic pressure, minimizing the vertical current density, minimizing some approximation to the total current density, and minimizing some approximation to the field's divergence. Of the automated methods requiring no human intervention, those which minimize the square of the vertical current density in conjunction with an approximation for the vanishing divergence of the magnetic field show the most promise.     

探地雷达在岩溶探测中的应用

利用探地雷达在芜湖--宣城高速公路上进行岩溶探测,通过分析雷达图像圈定了该区的岩溶发育位置,且雷达探测结果与钻探验证结果非常吻合.     

西北太平洋台风季节预报的数值模拟

利用中尺度气象模式WRF（weather research and forecasting）对2006年7月1日-9月30日的西北太平洋夏季台风进行了动力季节预报试验。结果表明：1）在对3个月以内的台风作动力季节预报试验时,WRF模式模拟的台风总个数与实况接近,模式模拟的总登陆台风数与实况相比偏小。从各月模拟情况看,台风总数与登陆数的模拟均与实况有差距。WRF模式对台风强度的模拟总体偏弱。2）WRF在模拟2006年7q月台风以及平均高度场、水平风垂直切变时,7月与实况接近,随时间增长,与实况的差别明显增大．WRF模式具有一定的台风动力季节预报能力,但其预报时限有待探讨。     

Sources of dissolved organic carbon in forest soils: evidences from the differences of organic carbon concentration and isotope composition studies

There is considerable discussion and uncertainty in the literature regarding the importance of fresh litter versus older soil organic matter as sources of soil dissolved organic carbon (DOC) in forest floor. In this study, the differences of organic carbon concentration and stable isotope composition were analyzed under different background conditions to identify the origins of DOC in forest soil. The data show that there is no significant difference in SOC content between these collected soil samples (P > 0.05), but the litter-rich surface soils have relatively higher DOC concentration than the litter-lacking (P < 0.01) ones, and the δ ¹³C values of DOC (δ ¹³C_DOC) are closer to δ ¹³C of litter than δ ¹³C values of SOC (δ ¹³C_SOC). In the litter-lacking surface soil samples, the range of δ ¹³C_DOC is between δ ¹³C_SOC and δ ¹³C of dominant plant leaves. These results suggest that DOC mainly derive from litter in the litter-rich surface soil with, and the main path of DOC sources may change with surrounding conditions. In addition, δ ¹³C_SOC and δ ¹³C_DOC become more positive, and the absolute values of Δ (δ ¹³C_DOC − δ ¹³C_SOC) decrease with depth in the soil profiles, which indicate that the percentage of DOC below 5 cm, derived from degradation of humus, may increase with soil depth.     

Croundwater Evolution and its Influence on the Fragile Ecology …

塔里木盆地南缘第四系松散沉积物以第三系弱透水层为隔水底板构成良好的储水场所含水层厚２００～９００ｍ,主要由冲洪积卵砾石、砂砾石和细砂组成。地下水位埋深由山前倾斜平原的５０～１００ｍ逐渐过渡为细土平原的１～３ｍ,矿化度相应地由１～３ｇ．Ｌ＾－１变化到３～５ｇ．Ｌ＾－１。大部分地下水由地表径流和渠系、田间灌溉水入渗转化而成,约占地下水补给总量的９４％以上。人类历史时期,气候地下水演变中依旧起着主导作用     

Dynamic design and construction of highway cut slopes in Huangshan area, China

Deformation and failure of high slope impact the construction and operation safety of highway in the mountainous areas. The deformation and failure are mainly caused by poor design which normally has not well combined with the geological conditions and unplanned construction. Therefore, effective design and construction management should be conducted for ensuring a successful construction without damage and risk. In light of the reality of high slope construction along highway in the Huangshan area, this paper proposes a technical procedure for dynamic design and construction management of high slopes along highway in the mountainous area. The proposed construction management scheme is divided into three phases, i.e., 1) design phase, 2) preparation phase of excavation, and 3) construction phase. During the design phase, experiences and lessons learnt from the design and construction of other high slopes along highway in the same region are summarized. The number of slopes and slope height should be optimized from the aspects of route selection and route form. During the preparation phase of excavation, “Excavation Permit Management System” should be adopted, and construction scheme should be made by the construction unit, then the scientific research and design unit determine whether it guarantees slope stability and makes optimization measures. During the construction phase, the scientific research unit would make proposal of optimization design, and apply the achievements of scientific research into practice through common efforts of various units based on the understanding of excavation and investigation. The management system mentioned above is adopted to conduct dynamic design and construction management for more than 90 slopes along the Huangshan — Taling — Taolin Expressway, and successful results of application have been achieved.     

Experimental Study and System Identification of Hydrodynamic Force Acting on Heave Damping Plate

Although Morison equation is often applied for simulating hydrodynamic force of marine structure, it may give poor results when non-linear behavior is severe or random wave is encountered. This leads to some modifications of Morison equation or other methods for predicting hydrodynamic force. One of them is the system identification technique. In this paper, NARMAX model theory is firstly used to identify the hydrodynamic system of heave damping plates, which are commonly installed on spar platform. Both linear and non-linear models are obtained. The comparisons between the predieted results and measured data indicate that NARMAX model can predict hydrodynamic force of a heave damping plate very well. The measured data for identification originate from forced oscillation tests, which are random records with given spectrum. The forced oscillation forms in experiment also contain simple harmonic, multi-frequency ones.     

Adaptation of agriculture to warming in Northeast China

Northeast China comprises Heilongjiang, Jilin and Liaoning Provinces, with a total area of 790,000 km² and a population of about 107 million. Northeast China, located at relatively high latitudes, (from about 39 to 53°N), is one of the coolest regions in China with long and cold winters, a short growth season and frequent cold extreme events, which are adverse to agricultural production. However, since the 1980s, Northeast China has experienced significant warming with annual mean temperature rising by 1.0–2.5°C. The increase of accumulated temperature, the extension of the growth period and the recession of summer cool disasters all contributed to improved conditions for crop growth and led to a northward movement of the agricultural climate zone. In addition, the adaptation to warming including the adjustment of crop composition and structure as well as the adoption of advanced technologies greatly facilitated agricultural development. As a result, total grain production in the region increased rapidly. This paper describes in detail climate change, adaptation measures and final agricultural outcomes, alongside with economic and political factors and the role of different political actors in Northeast China.     

长江防洪决策支持系统——数据库及其信息查询系统

针对长江防洪决策支持系统的需要,在分析研究防洪决策支持系统数据库和信息查询特点以及开发方法的基础上,采用先进的系统开发方法和可视化的编程工具,在微型计算机上使用Windows开发平台完成了水情数据库、工程数据库的开发和部分信息查询系统的程序设计.所建数据库和信息查询系统是一个内容丰富、数据结构复杂的子系统,也是一个数据规范性较强、结构合理、具有较高灵活性、可维护性和可扩充性的子系统.     

应用S930树脂富集薄样-X射线荧光光谱现场分析环境水体中8种重金属的方法研究

使用便携式X射线荧光光谱法结合富集技术已能分析液体样品中近20种金属元素,但检出限相对较高(0.1~100μg/L)、富集操作繁多、一种富集法可测元素种类较少等因素制约了该技术的发展。本文研究了一种适应于现场测试环境水样的XRF分析方法。使用20 mg S-930螯合树脂对100 m L水体中8种重金属(V、Mn、Fe、Co、Ni、Cu、Zn和Pb)进行预富集,控制溶液p H=4,搅拌30 min,经真空抽滤系统过滤制得均匀薄样,再使用自制的双层膜包夹样品盒并利用小型台式波长色散XRF测定。结果表明,8种元素标准曲线的相关性R20.997,检测范围为10~1000μg/L,检出限为1.0~6.2μg/L,方法精密度(RSD,n=12)小于5%,加标回收率为80%~120%;标准水样和模拟水样的测定结果分别与标准值和理论值基本一致。本方法巧妙地使用双层聚丙烯膜包夹薄试样的制样方法,较好解决了薄膜样品的污染等问题,简化了水样的预富集操作,制备的树脂薄样可直接供XRF测量。方法检出限较低,稳定性较好,适用于检测Ⅰ~Ⅴ类水体中Fe、Co、Ni和Cu,Ⅱ~Ⅴ类水体中V和Zn,Ⅲ~Ⅴ类水体中Mn和Pb,基本具备对8种重金属污染水体进行环境监测、水质调查等现场分析的能力。