Clay mineral composition of shelf sediments off the east coast of India

The clay mineral composition of the sediments carpeting the continental shelf off the east coast of India has been determined by X-ray and Differential Thermal Analysis techniques. Sediments contributed by the Ganges-Brahmaputra system of rivers are composed of about equal quantities of chlorite and illite with a small amount of montmorillonite and a trace of kaolinite. On the other hand, sediments from near the confluence of the Godavari river are composed of a mixture of very poorly ordered clay minerals; and those derived from the Krishna river comprise illite, montmorillonite, and mixed-layers of these minerals. Sediments off Visakhapatnam, which are accumulating at a place relatively free from the influence of the terrigenous influx from the major rivers, are composed of illite, montmorillonite, mixed-layer montmorillonite and illite, with a trace of chlorite, and kaolinite. The contrasted clay mineral assemblages have been attributed primarily to the difference in the source rocks and their weathered products in the respective drainage basins of these rivers rather than to diagenesis in the marine environment.     

Residual currents and corridor of flow in the Rio de la Plata

The Rio de la Plata is a large and shallow water body that discharges onto the Atlantic Ocean. The main driving forces for the river flow are the bathymetry, tides, the outflow from the Paraná and Uruguay rivers and the winds. A numerical model covering the entire river was set up with the objective of increasing our understanding of the hydrographical features and morphological dynamics in the Estuary. The simulations revealed a counter-clockwise residual circulation in the Samborombón Bay and an eastward net flow near the Uruguayan coast. The residual flow is forced by both the tides and the bathymetry. The residence time for the entire river ranges from 40 to 80 days. However, residence times above 120 days was found in the Samborombón Bay. Three corridors of flow have been identified.     

Man-made plutonium in freshwater and marine environments

Significant concentrations of plutonium isotopes are found in lake and coastal marine sediments accumulating at rates of 1–5 mm/yr. The activity levels of^{239, 240}Pu range between 0·7–3·3 dpm/g for post 1960 sediments. The measured and the calculated integrated activities of²³⁹Pu in the lake sediments are in agreement. This suggests that plutonium is chemically reactive in freshwater environments and it is removed to sediments from the water column shortly after its injection. A delay of about three years has been observed between the peak of plutonium fallout and its incorporation in the varved sediment from Santa Barbara basin. Based on this observation the mean size of particles transporting plutonium to the basin sediments is estimated to be about three microns. The usefulness of plutonium isotopes as a tracer nuclide for estimating sedimentation rates for the last two decades have been evaluated.     

Sensitivity of hypersaline Arabian Gulf to seawater desalination plants

Due to the hot, arid nature of its bordering lands, seawater in the Arabian Gulf can have significant evaporation rates leading to hypersaline conditions. If additional desalination plants were to operate along its coast, then the extraction of desalinated water and returned brine waste stream into the Gulf would increase the salinity. This paper uses a tidally and cross-sectionally averaged mathematical model that reveals multiplicative dependence of the salinity on factors associated with river flow, evaporation rates and each of the desalination plants. Present-day desalinated water production rates are in the linear regime, but hypersalinity has exponential sensitivity to the position and volumetric rate of desalinated water extraction.     

Confluences of agendas: Emigrant mathematicians in transit in Denmark, 1933–1945

The present paper analyses the confluence of agendas held by Danish mathematicians and German refugees from Nazi oppression as they unfolded and shaped the mathematical milieu in Copenhagen during the 1930s. It does so by outlining the initiatives to aid emigrant intellectuals in Denmark and contextualises the few mathematicians who would be aided. For most of those, Denmark would be only a transit on the route to more permanent immigration, mainly in the US. Thus, their time in Copenhagen would exert only temporary influence over Danish mathematics; but as it will be argued, the impacts of their transit would be more durable both for the emigrants and for the Danish mathematical milieu. It is thus argued that the influx of emigrant mathematicians helped develop the institutional conditions of mathematics in Copenhagen in important ways that simultaneously bolstered the international outlook of Danish mathematicians. These confluences of agendas became particularly important for Danish mathematics after the war, when the networks developed during the 1930s could be drawn upon.     

Isotopes of uranium and radium in Indian rivers

The concentrations of dissolved uranium and radium isotopes have been determined in the waters of several Indian rivers. The concentration of uranium (U-238) is found to vary between 0·01–7·0 micrograms/litre, depending primarily on the terrain through which the river flows. From the available data on the activity ratios, U-234/U-238, concentration of U-238 in rivers and the amount of uranium depositing on the ocean floor, a material balance calculation has been attempted. This shows that the supply of uranium to sea by rivers based on above measurements, is inadequate to explain the observed concentrations of U-238 and U-234 in the oceans. The Ra-226 concentration of river waters is found to be of the order of 0·1 dpm/litre (varying between 0·05–0·2 dpm/litre). The activity ratios, Ra-228/Ra-226, range between 1 and 4. This large variation is clearly related to the fact that the concentrations of the parent nuclides of Ra-226 and Ra-228 are different. The observed ratios are consistent with those expected from leaching of clays/soils; however, analogous to the situation in the case of uranium, the observed concentrations of radium isotopes in the oceans are too large to be explained by their influx by rivers.     

Studies on travancore monazite

Optimum conditions for the removal of phosphatic content in monazite sand by sintering with sodium carbonate are described in the previous papers in the series.? Results of investigation by D.T.A. and X-ray diffraction of the solid-solid reaction between monazite sand and sodium carbonate are now given. The D.T.A. curve shows that it is a slow exothermic reaction. X-ray diffraction patterns, besides confirming the constituents in the sintered product identified chemically, show the presence of a new phase.     

Digital Rock Physics: A case study of carbonate rocks

Digital Rock physics is a numerical framework applying image-based methods to determine effective material properties of rock. It is possible to find several of these methods in the literature, but we focused mainly in micro X-Ray Computed Tomography (µXRCT) to acquire the digital rock samples. After scanning the 3-D microstructure, morphological filters and numerical simulations were performed to characterize the samples. In particular carbonate rocks present a mismatch in numerical results compared to laboratory experiments. The elastic parameters, the P- and S-wave moduli, respectively,are overestimated when compared to ultrasonic measurements in the laboratory. We describe possible causes of this mismatch and propose a new segmentation technique to improve the correlation between numerical simulations and laboratory data. Furthermore, the workflow proposed for the characterization of carbonate rocks has been applied to different digitized samples from different sources, and a data driven material law has been found that fits better experimental results than the lower Hashin-Shtrikman bound. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

用概率统计方法预测洪水水位

河流的水位变化从局部时间看是偶然的，但从长远看，这些偶然的数据常常是必然的结果。在自然条件下取得的水位数据，从本质上看都是随机的，正因为其随机性，统计方法尤为重要。本文试用统计方法分析预测河水的最高洪水水位，这对建筑桥梁、修建堤坝具有一定的参考价值。     

Thermal study of some manganese oxide and hydrous oxide minerals

The minerals manganite, pyrolusite, ramsdellite, cryptomelane, psilomelane, braunite, lithiophorite and woodruffite from Sandur manganese ore deposits, Bellary District, Mysore State, which have been investigated by microscopic, chemical and X-ray methods (Naganna, 1963) are subjected to thermal study through differential thermal analysis and gravimetric thermal analysis. The hydrous oxides of manganese undergo dehydration below 400° C. and subsequent changes follow later. Most of the minerals containing MnO₂ thermally react in two stages, one at about 600° C. and the other beyond 800° C. The thermal behaviour of pyrolusite is seen to be similar to that ofβ MnO₂, while the thermal behaviour of ramsdellite is found to be similar to those ofα orγ MnO₂. Further the study suggests that ramsdellite may change over to pyrolusite below 500° C.     

X-Ray spectroscopic evidence for chemical bonding in manganese selenide (MnSe)

K absorption spectra of manganese and selenium have been recorded photographically in the pure metals and in the intermetallic compound manganese selenide (MnSe), employing a bent crystal X-ray spectrograph. It has been observed that the Mn K absorption discontinuity in MnSe shifts by 5·6 eV toward the high energy side with respect to the discontinuity in the pure metal. On the other hand, the Se K edge in MnSe is found to shift by 3·4 eV toward the low energy side with respect to the discontinuity in pure selenium. Also, emission work has revealed that the Mn K_β5 band in the compound shifts by about 5 eV toward the high energy side with respect to that in the pure metal. It has been shown that these results confirm the resonatingp ³ type of chemical bonding in the compound, as suggested theoretically by Pearson.     

黑龙江漠河地区冰雪情自动监测系统的设计与应用

基于空气、冰、雪与水物理特性的差异,设计了适应高寒地区内陆河道冰雪情定点自动检测的传感器和数据采集系统设备.该系统被安装在黑龙江省漠河县北极村水位站黑龙江河道断面,进行了3个半月的冰雪情定点连续监测,获取了系统的黑龙江河道内部冰水情以与积雪深度现场数据.采集数据完整地反映了黑龙江河道冬季冰层和雪层生消变化过程,为分析高寒地区冬季冰雪情变化规律以及春季凌汛预警提供了科学的预测数据,并探索出了一种适合野外恶劣环境下工程应用的冰雪情检测方法和系统设备.     

Long-term optimal operation of a parallel multireservoir power system

Long-term optimal operation of a multireservoir system is complex because it is a dynamic problem (present decisions for one reservoir depend on future decisions for all reservoirs); the optimal operating policy for one reservoir depends not only on its own energy content, but also on the corresponding content of each one of the other reservoirs; it is a highly stochastic problem with respect to the reservoir inflows and it is a nonlinear problem. This paper presents a new method for determining the optimal monthly operating policy of a power system consisting of multireservoirs on a multiriver system taking into account the stochasticity of the river flows. Functional optimization techniques and minimum norm formulation have been used. Results for a numerical example composed of three rivers with four reservoirs, three reservoirs, and two reservoirs on each river, respectively, are presented.This work was supported by the National Research Council of Canada, Grant. No. A4146.     

Numerical modelling of residual flow and salinity in the Río de la Plata

The Río de la Plata discharges into the Atlantic Ocean. The particular characteristics of the study area, the variable width and shallowness of the river, the high fluvial discharges and the dynamic processes involving interactions between river discharges, tidal currents and wind, generate complex velocity and salinity fields. We applied the hydrodynamic model RMA-10 to examine the effects of various forcing (tides, flow discharge and winds) on residual currents and salinity fields in the Río de la Plata, focusing on the outer zone of the river. The RMA-10 code, developed by Ian King, is a multiparameter finite element model representing estuarine flow in three dimensions. In this study the model has been applied in a depth-averaged-baroclinic mode and a series of observed data is used for model calibration and verification. The model result shows that it is able to simulate velocity and the salinity fields with a reasonable accuracy. The analysis of residual currents in the river, when forced by freshwater discharge and astronomical tide, shows that the flow discharge takes place mainly over the shallower areas of the river and that the saline water is advected up-river through the deeper channels. The numerical simulations show that the winds from the South-West and North-East quadrants have a great influence over the salinity and velocity fields.     

IMPACTS OF RECREATIONAL FISHING ON THE COMMERCIAL SECTOR: AN EMPIRICAL ANALYSIS OF ATLANTIC MACKEREL

There are often tensions between recreational and commercial uses of marine fisheries. The Atlantic mackerel along the coast of the United States and Canada is one such fishery. Although recreational catch is only a small percent of total catch, it has been suggested that recreational use be incorporated into a broad management scheme for the fishery. This paper measures the costs domestic commercial fishermen incur from the recreational harvest of Atlantic mackerel. The results indicate that the domestic commercial fishery, which takes only a small portion of total commercial catch, would see no significant gain from limiting recreational fishing. An earlier version of this paper was presented at the AERE Workshop on Sport and Commercial Fisheries. Participants at that conference, anonymous referees, and Peter Berck offered valuable suggestions which improved this paper. Any errors are my own.     

Multi-objective analysis of dam release flows in rivers downstream from hydropower reservoirs

This paper assesses dam releases from hydropower reservoirs in order to optimize power production and fish habitat protection. A multi-objective programming model includes output from 2-D hydraulic simulation for habitat assessment to optimize power production and fish habitat suitability as a Pareto set. To identify the optimal Pareto set two different approaches are used and compared: ε-constraint methods and non-dominant-sorting genetic algorithm (NSGA II). To formulate the ecological objective the river habitat quality is quantified by the weighted usable area (WUA). The relation between the WUA and the river flow-rate is obtained by using a 2D hydraulic model in which the hydraulic characteristics of river current – depth and velocity – are calculated by a finite difference numerical integration of two-dimensional shallow water equations on a boundary fitted non orthogonal curvilinear mesh. This approach allows the integration of motion equations on geometrically complex domains as those representing the morphology of natural watercourses. The performance of the proposed methodology is analyzed in a case study of a stretch of the Piave river downstream of the dam of the Pieve di Cadore reservoir (Belluno, Italy).     

Problem solving in Chinese mathematics education: research and practice

This paper is an attempt to paint a picture of problem solving in Chinese mathematics education, where problem solving has been viewed both as an instructional goal and as an instructional approach. In discussing problem-solving research from four perspectives, it is found that the research in China has been much more content and experience-based than cognitive and empirical-based. We also describe several problem-solving activities in the Chinese classroom, including “one problem multiple solutions,” “multiple problems one solution,” and “one problem multiple changes.” Unfortunately, there are no empirical investigations that document the actual effectiveness and reasons for the effectiveness of those problem-solving activities. Nevertheless, these problem-solving activities should be useful references for helping students make sense of mathematics.     

Numerical modelling of storm surges in the Arabian Sea

Using the basic hydrodynamic equations governing motion in the sea, a coastal zone numerical model has been developed for the prediction of storm surges along the west coast of India. Numerical experiments were performed with the help of this model to simulate the surge generated by the devastating 1975 Porbandar cyclone. The results of the experiments were in good agreement with the reported values along the Gujarat coast.     

Optimal scheduling of reservoir releases during flood: Deterministic optimization problem,part 2, case study

This paper applies the optimization procedure developed in Part 1 to the problem of the optimal scheduling of reservoir releases during flood in the case study concerning the river system of Upper Vistula in Poland. Technical details related to the implementation of the proposed algorithm are discussed.The research reported here has been supported by the Central Basic Research Program CPBP-03.09, Metody Analizy i Uytkowania Aasobow Wodnych, Polish Academy of Sciences, Warsaw, Poland. This support is kindly acknowledged.