10Be dating of Younger Dryas Salpausselkä I formation in Finland

Boulders of the Younger Dryas Salpausselkä I (Ss I) formation west of Lahti, southern Finland, were sampled for surface exposure dating. The ¹⁰Be concentrations, determined by accelerator mass spectrometry, yield minimum exposure ages of 11 930 ± 950, 11 220 ± 890, 11 050 ± 910 and 11 540 ± 990 years, using recently published production rates scaled for latitude and elevation. This includes a correction to the production rate resulting from postglacial uplift of the Fennoscandian lithosphere (i.e. changing elevation) during the time of exposure. The error‐weighted mean exposure age of 11 420 ± 470 years of the analysed boulders agrees with previous varve dates of Ss I, which range from 11 680 to 11 430 calendar years BP. However, erosion has to be taken into account as a process affecting rock surfaces and therefore influencing exposure ages. Available information suggests an erosion rate of 5 mm/kyr, which increases the error‐weighted mean exposure age to a value of 11 610 ± 470 years. Within the errors, the formation of Ss I in the Vesala area west of Lahti falls into the Younger Dryas time bracket, as defined by the GRIP and GISP 2 ice core (Greenland).     

Estimation of error in the determination of Al in stone meteorites by indirect γ-ray spectrometry

The error involved in the determination of the Al²⁶ concentration by the method of Rowe and his co-workers was measured and the values they reported should be increased by a factor of 1.36 ± 0.05. The potassium contents of the meteorites measured by Roweet al., are not affected by this error and can be used with confidence.     

Determination of in situ stresses from excavation-induced stress changes

The state of in situ stress described by the magnitudes and orientations of the principal stresses is an important design parameter for the construction of underground openings. Conventional methods of in situ stress determination, such as overcoring, only provide information for a small domain and are usually very costly. In this paper, a method for field stress determination in a volume of rock that is representative for an underground opening is presented. This method requires the measurement of stress changes induced by the excavation of an opening (tunnel). The best fit stress field is then determined by comparing measured and predicted stress changes. An error function is defined between the two sets of stress changes and the best-fit solution is obtained by error minimization. The methodology and its applicability are explained by an example of a circular opening for which closed form solutions are available. Application of this method to a case study has shown great potential. The back-analyzed stresses are extremely close to those determined by a large number of overcoring tests. Compared with conventional techniques of stress determination, this new method is superior in that:

Development of an empirical model for predicting peak breach flow of landslide dams considering material composition

The existing empirical models do not consider the influence of material composition of landslide deposits on the peak breach flow due to the uncertainty in the material composition and the randomness of its distribution. In this study, based on the statistical analyses and case comparison, the factors influencing the peak breach flow were comprehensively investigated. The highlight is the material composition-based classification of landslide deposits of 86 landslide cases with detailed grain-size distribution information. In order to consider the geometric morphology of landslide dams and the potential energy of dammed lakes, as well as the material composition of landslide deposits in an empirical model, a multiple regression method was applied on a database, which comprises of 44 documented landslide dam breach cases. A new empirical model for predicting the peak breach flow of landslide dams was developed. Furthermore, for the same 44 documented landslide dam failures, the predicted peak breach flow obtained by using the existing empirical models for embankment and landslide dams and that obtained by using the newly developed model were compared. The comparison of the root mean square error (E_rms) and the multiple coefficient of determination (R²) for each empirical model verifies the accuracy and rationality of the new empirical model. Furthermore, for fair validation, several landslide dam breach cases that occurred in recent years in China and have reliable measured data were also used in another comparison. The results show that the new empirical model can reasonably predict the peak breach flow, and exhibits the best performance among all the existing empirical models for embankment and landslide dam breaching.

     

Isotherms for the sorption of zinc and copper onto kaolinite: comparison of various error functions

In this research, the equilibrium sorption of Zn(II) and Cu(II) by kaolinite was explained using the Freundlich, Langmuir and Redlich–Peterson isotherms, via both linear and non-linear regression analyses. In the case of non-linear regression method, the best-fitting model was evaluated using six different error functions, namely coefficient of determination (r ²), hybrid fractional error function (HYBRID), Marquardt’s percent standard deviation (MPSD), average relative error (ARE), sum of the errors squared (SSE) and sum of the absolute errors (EABS). The examination of error estimation methods showed that the Langmuir model provides the best fit for the experimental equilibrium data for both linear and non-linear regression analyses. The SSE function was found to be a better option to minimize the error distribution between the experimental equilibrium data and predicted two-parameter isotherms. In the case of three-parameter isotherm, HYBRID was found to be the best error function to minimize the error distribution structure between experimental equilibrium data and theoretical isotherms. Non-linear method was found to be more appropriate method for estimating the isotherm parameters.     

Studies on an efficient method for determining ethyl carbamate in the workplace air

In relation to the proposal to introduce an occupational exposure limit value for ethyl carbamate (EC) in Poland, a need to develop a sensitive method for determination of this carcinogenic substance in the workplace air was emerged. In the presented paper, a new method for its determination by high-performance liquid chromatography (HPLC) with fluorescence detector (FLD) is proposed. The method is based on the adsorption of EC on the cellulose filter, its extraction with water, further reaction of EC with 9-xanthydrol in acidic solution. Determination of the obtained EC derivative (N-xanthyl ethyl carbamate) was then conducted in a reverse-phase system with acetonitrile and water mobile phase at a flow rate of 1 mL/min on an Ultra C18 column of 250 mm by HPLC–FLD. Measurement range of 0.1–2 µg/m³ for a 1440 L of air sample was appropriate to the established maximum admissible concentration value of 1 µg/m³. The limit of detection is 0.142 ng/mL, and the limit of quantification is 0.426 ng/mL, respectively. The developed quantitative method makes it possible to determine ethyl carbamate in workplace air, which in turn allows determining exposure indicators and facilitates occupational risk assessment for the employees.     

A stable space-time FE method for the shallow water equations

We consider the finite element (FE) approximation of the two dimensional shallow water equations (SWE) by considering discretizations in which both space and time are established using a stable FE method. Particularly, we consider the automatic variationally stable FE (AVS-FE) method, a type of discontinuous Petrov-Galerkin (DPG) method. The philosophy of the DPG method allows us to establish stable FE approximations as well as accurate a posteriori error estimators upon solution of a saddle point system of equations. The resulting error indicators allow us to employ mesh adaptive strategies and perform space-time mesh refinements, i.e., local time stepping. We establish a priori error estimates for the AVS-FE method and linearized SWE and perform numerical verifications to confirm corresponding asymptotic convergence behavior. In an effort to keep the computational cost low, we consider an alternative space-time approach in which the space-time domain is partitioned into finite sized space-time slices. Hence, we can perform adaptive mesh refinements on each individual slice to preset error tolerances as needed for a particular application. Numerical verifications comparing the two alternatives indicate the space-time slices are superior for simulations over long times, whereas the solutions are indistinguishable for short times. Multiple numerical verifications show the adaptive mesh refinement capabilities of the AVS-FE method, as well the application of the method to some commonly applied benchmarks for the SWE.

     

Prediction of river flow using hybrid neuro-fuzzy models

The complex nature of hydrological phenomena, like rainfall and river flow, causes some limitations for some admired soft computing models in order to predict the phenomenon. Evolutionary algorithms (EA) are novel methods that used to cover the weaknesses of the classic training algorithms, such as trapping in local optima, poor performance in networks with large parameters, over-fitting, and etc. In this study, some evolutionary algorithms, including genetic algorithm (GA), ant colony optimization for continuous domain (ACO_R), and particle swarm optimization (PSO), have been used to train adaptive neuro-fuzzy inference system (ANFIS) in order to predict river flow. For this purpose, classic and hybrid ANFIS models were trained using river flow data obtained from upstream stations to predict 1-, 3-, 5-, and 7-day ahead river flow of downstream station. The best inputs were selected using correlation coefficient and a sensitivity analysis test (cosine amplitude). The results showed that PSO improved the performance of classic ANFIS in all the periods such that the averages of coefficient of determination, R², root mean square error, RMSE (m³/s), mean absolute relative error, MARE, and Nash-Sutcliffe efficiency coefficient (NSE) were improved up to 0.19, 0.30, 43.8, and 0.13%, respectively. Classic ANFIS was only capable to predict river flow in 1-day ahead while EA improved this ability to 5-day ahead. Cosine amplitude method was recognized as an appropriate sensitivity analysis method in order to select the best inputs.     

碘量法测定铜矿石中铜方法的改进

针对铜矿石中铜含量的测定方法——碘量法在应用过程中存在碘的挥发及碘化铜沉淀对碘的吸附所引起的误差问题,通过大量的调研和试验提出改进方案,即在聚乙烯醇存在下碘量法测定铜,增大了碘化铜沉淀的溶解度;聚乙烯醇与碘生成较稳定的络合物,减小了碘的挥发损失,操作简单;聚乙烯醇可直接代替淀粉作指示剂,成本低廉。     

标准加入-原子吸收光谱法测定钢渣中的铁

样品经硝酸-氢氟酸混合酸溶解后,用标准加入-原子吸收光谱法测定钢渣中的铁.实验探讨了钢渣的均匀性等干扰因素对结果的影响,并提出基体高、浓度高的样品稀释倍数过高误差越大,建议采用如旋转燃烧头、选择次灵敏线等降低仪器灵敏度的方法或采用标准加入法.并将标准加入法与X射线荧光光谱、电感耦合等离子体发射光谱、原子吸收光谱直接测定法进行比较,铁的实验结果分别为51.6%、54.2%、46.2%、16.6%,相对标准偏差分别为2.8%、5.3%、2.0%、2.3%.标准加入-原子吸收光谱法用于测定基体高、浓度高的样品是准确可靠的.方法可用于环境类实验室用水剂标准溶液进行钢渣类样品中元素的分析.     

高浓度示差分光光度法测定钢厂循环管道除垢污水中的总磷

循环水及污水中总磷的国家标准方法是用分光光度法测定,当样品中有机磷含量高时,分解易碳化,操作繁琐,分析误差大.本文应用磷钼黄显色示差分光光度技术测定某钢厂循环管道除垢污水中的总磷,通过正交实验确立了采用硝酸-高氯酸消解样品,将样品中聚磷酸盐、有机磷酸盐转化为正磷酸盐,在硝酸溶液中,正磷酸盐与钒钼酸铵作用生成可溶性黄色磷钒钼酸配合物,基于其颜色强度与磷的浓度成正比测定高浓度磷的含量.实验对使用的氧化剂用量、溶解温度、显色条件、测定波长进行优化,结果表明,磷含量在10.0 ～ 40.0 mg/L范围符合朗伯-比尔定律,方法精密度(RSD)＜1.0％(n=5),加标回收率为98.8％～105.0％.建立的示差光度法比一般光度法相对误差小,准确度更高;与电感耦合等离子体发射光谱法的测定结果基本吻合,且测定成本更低.     

应用高频红外碳硫仪测定农用地土壤样品中有机质含量

应用高频红外碳硫仪测定农用地土壤样品中的有机质,避免了传统方法中的试样液体转化环节,测定效率高,但存在土壤样品电磁感应低和基体影响较大等问题。本文通过实验优化了样品称样量、助熔剂铁和钨的添加量等测定条件,结果表明：当样品称样量为0.05g、助熔剂铁添加量为0.40g、钨添加量为1.50g时,有机质测定效果最佳。通过土壤标准物质进行验证,方法检出限为0.003%,相对标准偏差（RSD,n=7）小于4%,测定值与认定值的相对误差小于5%,且不同分析人员的测定结果间没有显著差异。采用本法与重铬酸钾容量法对甘肃省农用地土壤样品进行测定,两种方法测定值的绝对误差为-0.25%~0.28%,测定结果之间呈极显著线性正相关（R²=0.9736）,表明两种方法的一致性很好。本方法的检出限、精密度、准确度均满足农用地土壤样品有机质测定要求。     

顾及系统误差的GEO卫星几何法定轨PDOP值分析

针对GEO卫星几何法定轨中系统误差对PDOP值的影响进行研究,首先回顾了经典几何法定轨的基本原理,然后根据顾及系统误差的几何法定轨原理推导出PDOP值计算公式,并利用5个跟踪站的模拟数据,计算了多种系统误差情况下PDOP值。结果表明：系统误差对GEO卫星几何法定轨的PDOP值影响很大;采用顾及系统误差的几何法定轨方法可以较好地削弱系统误差对PDOP值的影响;国外布设跟踪站比仅在中国布设跟踪站能更好地削弱系统误差对PDOP值的影响。     

江苏连云港地区滨海相软土地质特性研究

根据江苏连云港地区大量的工程地质勘察资料，就该区软土层的因类型、物理力学特性、室内试验问题、现场原位测试，特别是力学指标的确定进行了深入的探讨和分析，结果表明：室内试验确定连云港 地区软土力学指标误差大，有些指标与实际误差在2倍以上，常难以气氛。用十字板、CPT方法有较好的效果。     

基于铸体薄片资料的砂岩储层孔隙度演化定量计算方法--以鄂尔多斯盆地环江地区长8储层为例

利用铸体薄片资料进行储层孔隙度演化定量计算是一项重要的成岩演化和储层模拟技术,但由于参数确定和计算方法存在的问题,导致结果准确性较差。基于此,在分析前人计算方法及其误差的基础上,确定了计算参数的选用,改进和完善了计算方法与结果检验方法的应用。在初始孔隙度的确定上,相对赋一固定值作为所有样品初始孔隙度或Scherer拟合公式,根据Beard和Weyl湿砂填集实验恢复初始孔隙度具有较高的精度;在考虑压实过程中岩石表观体积缩小的情况下,推导了压实、胶结损失孔隙度与溶蚀增加孔隙度计算公式,并给出了忽略岩石表观体积变化时孔隙度演化分析的误差来源和可能的误差大小范围;结果检验方面,摒弃了以往忽略溶蚀增加孔隙度而简单进行粒间孔隙度与和氦孔隙度对比的较为粗略的方法,建立了考虑各种成岩作用结果和成岩过程中岩石表观体积变化情况下的结果检验方法。应用该方法对鄂尔多斯盆地环江地区长8储层孔隙度演化进行计算,结果与岩芯氦孔隙度相比,绝对误差-1.1%,相对误差15.3%,取得了良好的应用效果。     

Semi-automatic determination of the carbon and oxygen stable isotope compositions of calcite and dolomite in natural mixtures

A semi-automatic, on-line method was developed to determine the δ¹³C and δ¹⁸O values of coexisting calcite and dolomite. An isotopic mass balance is used to calculate the compositions of dolomite after having measured that of calcite and of the “bulk” sample. The limit of validity of this method is established by performing isotopic measurements of artificial mixtures made of precisely weighted and isotopically-characterised dolomite and calcite. The accuracy and repeatability of the calculation of dolomite δ¹³C and δ¹⁸O are statistically determined with a Monte-Carlo procedure of error propagation. Stable isotope ratios are determined by using an automated MultiPrep™ system on-line with an isotope-ratio mass-spectrometer (IRMS). The reaction time and the temperature of reaction were optimised by comparing the results with the isotopic composition of known mixtures. The best results were obtained by phosphoric acid digestion after 20 min at 40 °C for calcite and 45 min at 90 °C for dolomite. This procedure allows an accurate determination of the isotopic ratios from small samples (300 μg). Application of this protocol to natural mixtures of calcite and dolomite requires the accurate determination of the relative abundance of calcite and dolomite by combining Mélières manocalcimetry (MMC) and X-ray diffractometry (XRD).     

Modelling soil erosion from a watershed using cubic splines

Erosion in a watershed exhibits spatial and temporal variability, and its determination is fundamental to determining sediment yield which is a key to proper watershed management. In this study, we propose a relationship between the curve number (SCS 1956) and Sediment Yield Index (SYI) using cubic splines. The method is illustrated with a case study of one watershed of Narmada Basin located in Mandla district of Madhya Pradesh, India. Cubic splines are found to perform satisfactorily with Nash efficiency of 63.64%, absolute prediction error of 2.64%, integral square error of 1.22%, coefficient of correlation of 93.78% and degree of agreement of 0.99%. The relation between observed and computed SYI values is correlated with a coefficient of determination (R ²) of 0.87. Such a relationship can be used to determine SYI from the available CN value, which may be quite useful in field applications.     

A Comparison of Two-Phase Dynamic Upscaling Methods Based on Fluid Potentials

Although a number of methods for calculating dynamic pseudo-functions have been developed over the years, there is still a lack of understanding as to why a certain method will succeed in some cases but fail in others. In this paper, we describe the results of an assessment of several upscaling methods, namely the Kyte and Berry (KB) method, the Stone method, the Hewett and Archer (HA) method and the Transmissibility-Weighted (TW) method. We have analyzed the equations for deriving the methods and investigated the results of numerical simulations of gas displacing oil, in a variety of models to enable us to gain new insights into these, and related, upscaling methods. In particular, some novel observations on methods based on fluid potential are presented and the issue of using predicted fluid mobilities as a criterion of accuracy of an upscaling method is clarified.     

广东高凤金矿形成时代的Rb-Sr、40Ar-39Ar年龄测定

用含金石英脉流体包裹体Rb-Sr和⁴⁰Ar-³⁹Ar方法测定了广东高凤金矿的形成时代为印支期(215×10⁶a)。两种方法的结果在误差范围内完全一致，两种测定方法相互验证，结果准确可靠。研究表明含金石英脉流体包裹体Rb-Sr和⁴⁰Ar-³⁹Ar年代方法对于解决石英脉型金矿的成矿时代具有很好的应用前景。     

Tephrochronology,magnetostratigraphy and mammalian faunas of Middle and Early Pleistocene sediments at two sites on the Old Crow River,northern Yukon Territory,Canada

Alluvial and lacustrine sediments exposed beneath late Pleistocene glaciolacustrine silt and clay at two sites along the Old Crow River, northern Yukon Territory, are rich in fossils and contain tephra beds. Surprise Creek tephra (SZt) occurs in the lower part of the alluvial sequence at CRH47 and Little Timber tephra (LTt) is present near the base of the exposure at CRH94. Surprise Creek tephra has a glass fission-track age of 0.17 ± 0.07 Ma and Little Timber tephra is 1.37 ± 0.12 Ma. All sediments at CRH47 have a normal remanent magnetic polarity and those near LTt at CRH94 have a reversed polarity — in agreement with the geomagnetic time scale. Small mammal remains from sediments near LTt support an Early Pleistocene age but the chronology is not so clear at CRH47 because of the large error associated with the SZt age determination. Tephrochronological and paleomagnetic considerations point to an MIS 7 age for the interglacial beds just below SZt at CRH47 and at Chester Bluffs in east-central Alaska, but mammalian fossils recovered from sediments close to SZt suggest a late Irvingtonian age, therefore older than MIS 7. Further studies are needed to resolve this problem.