An Instrument for the Determination of a Hydropneumograph in a Bubbling Spring

In order to enable greater accuracy in the determination of the mass discharge of gas and water-gas ratios (WGR) in groundwater from springs, we have developed a field-deployable instrument using commercially available components to independently measure the gas and water mass flow rates in springs with bubbling mixed-phase flow. Collecting and measuring the free gas phase will allow for further compositional analysis that may be useful in improving gas-derived parameters such as recharge temperature and age, as well as quantification of methanogenesis and flux of crustal/mantle gasses. By installing a phase separator at the spring discharge, a thermal mass flow sensor is utilized to measure the gas flow rate (ebullition + flux) generated from a spring. The water flow rate is determined by a standard weir. Field performance of the device was tested on a spring discharging from the Arbuckle-Simpson aquifer near the town of Connerville in south-central Oklahoma, USA.     

Method for the determination of the height of a solar filament

A comparison of the actual filament height above the solar photosphere with the limiting height calculated by magnetic data provides information about the filament stability margin and its readiness for eruption. A method is proposed for the determination of the height of solar filaments by a comparison of the position of the upper edge of the filament (spine) with the position of the polarity-inversion line of the potential magnetic field calculated for different heights. The line closest to the filament spine corresponds to its height. Observations of the Solar Terrestrial Relations Observatory (STEREO) spacecraft were used to verify the proposed method when they were at an angular distance of ~90° from the Earth and provided a side view of the filaments near the central meridian in observations from the Earth and near-Earth orbits. The proposed method can be useful in the estimation of the possible geoeffectiveness of filaments on the solar disk.     

Conditions for the arrest of a vertical propagating dyke

Magma ascent towards the Earth’s surface occurs through dyke propagation in the vast majority of cases. We investigate two purely mechanical effects unrelated to cooling or solidification that lead to the arrest of propagation, so that no eruption occurs. The first is that the input of magma from the source is not maintained continuously, such that a fixed volume of magma is released. Laboratory experiments show that, in this case, the dyke stops at a finite distance from the source. This behaviour is specific to the fracturing process in 3-D. We derive a relationship for the minimum magma volume required for an eruption as a function of magma buoyancy and source depth. When large magma volumes are available, eruption may also be prevented by a thick low density layer in the upper crust. Numerical studies of dyke propagation show that the dyke continues to rise even though it is negatively buoyant. Magma accumulates in a swollen nose region at the interface between the low density layer and the dense basement. Magma overpressure is largest at this interface and increases with increasing penetration into the upper layer. It may become large enough to induce horizontal fractures in the dyke walls and lateral intrusion of a sill, which prevents eruption. This requires that the thickness of the low density layer exceeds a threshold value that depends on the density contrast between magma and host rock. If the magma volume is smaller than a threshold value, neither sill intrusion nor eruption are possible and magma gets stored in a horizontal blade-shaped dyke straddling the interface. Scaling laws for variations of ascent rate and for the minimum magma volume allow diagnosis of a failed eruption.     

New methods for measuring the permeability of rock samples for a single-phase fluid

A complex of methodology, instrumentation, and software tools is worked out, which makes it possible to accomplish high-precision measurements of permeability for a single-phase fluid and its anisotropy within a wide range of values both under the normal conditions and high temperature and pressure.The transient method, modified with allowance for the dependence of the properties of a percolating gas on the parameters of its state, enables one to simultaneously determine, from the data of a single experiment, the permeability values for a sample of condensed fluid and the Klinkenberg constant, which characterizes the pore space of rock. This approach made it possible to substantially increase the accuracy of measurements, reducing their labor-intensiveness.The method of varying the flow shape makes it possible to simultaneously determine, in the course of a single experiment, the axial and radial components of the permeability tensor of anisotropic rocks with layered structure. The instrumentation and software implementing these new methodologies are developed and thoroughly tested.     

A Tool for Forecasting the Arrival Time of a Tracer or a Pollutant at a Karst Spring

Karst aquifers are a groundwater resource of global importance. Protection and contamination of karst water resources are often tackled by means of land-use planning and monitoring of physico-chemical and microbial water properties coupled to early-warning systems. However, these solutions of management do not integrate observational data on karst hydrodynamic, for example, tracer tests. Thus, this technical note aims at introducing a straightforward method for forecasting the arrival time of a tracer or a pollutant at a karst spring. Deliverables from the proposed method can assist professionals in the case of a pollution involving a swallow hole of the karst network. The approach is based on repeated tracer testing, gauging of spring flow rate and mathematical curve fitting. Tracer tests and gauging of spring flow rates are repeated under low, middle, and high flow periods. Arrival times of tracer from a given swallow hole of the network are plotted as a function of measured flow rates at the karst spring. The observational data are finally fitted by a mathematical function. Flow rate monitoring at high-temporal resolution at the karst spring and the mathematical functions allow forecasting the arrival of a tracer or a pollutant at the spring in the case of an accident involving a swallow hole of the network or estimating the duration of a pollution if hydrodynamic conditions do not change abruptly. The applicability of the method is documented by three study sites in Switzerland.     

一次北京大暴雨过程低空东南风气流形成机制的数值研究

2002年6月24~25日,北京门头沟附近发生了一次大暴雨过程.观测资料和数值模拟均发现,在暴雨发生前和发生过程中,北京地区边界层内出现了一支强盛的东南风气流.东南风气流沿太行山东坡爬升,触发了对流.为探讨这支低空东南风气流的形成原因,本文通过数值模拟和敏感性试验,对这支东南风气流的形成机制进行了研究.结果表明,这支低层东南风气流是一支冷湿的、伴有较强风速辐合的气流,主要是在天气尺度系统作用下生成的.东南风气流形成过程中,地表感热加热作用对其强度有加强作用.大暴雨开始后的潜热加热作用对这支东南风气流有正反馈作用,使气流的强度大大增强,因此,在降水开始后气流强度也增强,降水最强时低空急流的强度达最强.暴雨开始后,由于夜间地表降温造成山风效应,导致在北京西部山脚下出现偏北风.     

Modifications of the dispersion relations for surface waves in a layer on a half-space

Summary Dispersion relations for Love and Rayleigh waves in a layer on a half-space are modified by introducing quadratic slownesses instead of velocities. The advantages of this approach are demonstrated on analytical formulae for computing the group velocity.     

Effectiveness of a market-based instrument for the allocation of water in a tropical river environment

The seasonal nature of Australia’s tropical rivers means that connected groundwater aquifers are an important source of both consumptive and non-consumptive water, particularly during the dry season. The management of these common pool groundwater resources is one of the predominant water issues facing northern Australia. A national program of water reform stipulates the expansion of water trading as a key instrument for water allocation. The effectiveness of new institutional arrangements such as water markets will be determined mostly by how well they coordinate with local environmental requirements, local institutions and local norms. This paper describes a novel application of combined field work, institutional analysis, experimental economics and agent-based modeling to the analysis of a potential water market in the Katherine region of the Northern Territory, Australia. The effectiveness of different versions of the policy instrument is assessed in light of local conditions. Instruments that enable personal relationships and local institutions and norms to play a role in water management are found to be more effective in terms of both farming income and environmental impact.     

框架塔自振频率的数值解法

框架和塔连接后可简化为一个弹性支承的系统,利用弹性连续体分析法求解振动方程,推导出了计算框架塔自振频率的理论公式。试验结果表明:本模型的计算值与试验值吻合良好,可以为工程实践中的应用提供理论依据。     

On the variance of the stationary probability vector for a finite dam

A method for estimating the variance of the stationary probability vector for the finite dam is discussed. The method relies upon the constancy of a gradient matrix in the vicinity of the solution and a simple numerical differentiation technique is found to be adequate. An example of the variance calculation is given by applying the method to streamflow data previously used in an application of Moran's theory of dam to the Ord River project, Western Australia.     

Performance of methods for estimating the time of concentration in a watershed of a tropical region

The time of concentration (T_c) is a fundamental parameter in the design of hydrological projects for watersheds. In this study a graphical methodology is described for estimating T_c in a watershed, and this is applied to 17 rainfall–runoff events from a rural watershed located near the capital city of Mato Grosso do Sul State, in the Brazilian Cerrado. The T_c values obtained through the graphical method were compared to T_c values estimated using 20 equations from various references. The equations were selected by considering those that were not developed using data for urban watersheds, and the results of the graphical method were compared to those derived by applying the equations to sub-basin data. The graphical method was reliable in determining T_c, and Ventura’s equation was found to present the best performance for a rural watershed in a tropical climate region.     

Bayesian analysis of a dynamical model for the spread of the Usutu virus

The Usutu virus is an arbovirus transmitted by mosquitoes and causing disease in birds. The virus was detected in Austria for the first time in 2001, while a major outbreak occurred in 2003. Rubel et al. (2008) developed a nine-compartment deterministic SEIR model to explain the spread of the disease. We extended this to a hierarchical Bayes model assuming random variation in temperature data, in reproduction data of birds, and in the number of birds found to be infected. The model was implemented in R, combined with the FORTRAN subroutine for the original deterministic model. Analysis was made by MCMC using a random walk Metropolis scheme. Posterior means, medians, and credible intervals were calculated for the parameters. The hierarchical Bayes approach proved to be fruitful in extending the deterministic model into a stochastic one. It allowed for Bayesian point and interval estimation and quantification of uncertainty of predictions. The analysis revealed that some model parameters were not identifiable; therefore we kept constant some of them and analyzed others conditional on them. Identifiability problems are common in models aiming to mirror the mechanism of the process, since parameters with natural interpretation are likely to exhibit interrelationships. This study illustrated that Bayesian modeling combined with conditional analysis may help in those cases. Its application to the Usutu model improved model fit and revealed the structure of interdependencies between model parameters: it demonstrated that determining some of them experimentally would enable estimation of the others, except one of them, from available data.     

Current stabilizer for the magnetic field of a mass spectrograph

Summary A new automatic current stabilizer is constructed, which can be used for a magnetic field of a mass spectrograph. A stability of the order of 10^–6 is attained for relatively long intervals. The dependence of the magnetic field constancy on the different parameters of the stabilizer is investigated by methods of servomechanism.     

Some suggestions for the construction of a flat response seismograph

Summary A new circuit is suggested which allows the seismographs to afford a flat response to the ground displacement and to the ground velocity. The circuit is based on a rigorous integrator and it fits to any pendulum's damping.     

A model for the water regime of a deciduous forest

The relationships between actual evapotranspiration, atmospheric conditions and soil water content in the root zone are described in a simple functional model. Some constants which are used in these relationships, but unknown for forest areas, have been estimated for a deciduous forest near Zürich in Switzerland (Brülhart, 1969). On sufficiently humid soil the evapotranspiration of this forest was more than twice as high as for agricultural crops. On the other hand in the forest the evapotranspiration reacted much more sensitively on drying of the soil. On warm summer days (evaporation of free water about 0.4–0.6 cm per day) the trees considerably reduced their water delivery to the atmosphere at soil water suctions of slightly more then 0.05 bars (Fig. 7).     

On the validity of a model for the reversals of the Earth's magnetic field

Abstract

We have used techniques of nonlinear dynamics to compare a special model for the reversals of the Earth's magnetic field with the observational data. Although this model is rather simple, there is no essential difference to the data by means of well-known characteristics, such as correlation function and probability distribution. Applying methods of symbolic dynamics we have found that the considered model is not able to describe the dynamical properties of the observed process. These significant differences are expressed by algorithmic complexity and Renyi information.     

Methods for locating the proper position of a planned fishway entrance near a hydropower tailrace

The spatial distribution of upstream migrating Atlantic salmon (Salmo salar) spawners was studied in 2008 and 2009 in the surroundings of the tailrace from a hydropower station in the River Umeälven. This area is problematic because the fish have difficulties finding their way into the original riverbed, which prompted an investigation on the feasibility of adding a fishway in the area. Echo sounding was used in 2008 to investigate the spatial use of fish in the tailrace channel during the time of salmon migration. Presence of other fish species was so low that all echo sounding detections were assumed to be salmon. In 2009, data on wild radio-tagged salmon (n = 94) was collected in the same tailrace by an array of underwater antennas with a detection radius of approximately 10 m, to validate the results from the echo sounding. Both types of surveys showed aggregations of fish in one part of the tailrace. As a final step, Computational Fluid Dynamics (CFD) modeling was performed to analyze hydrodynamics. This CFD modeling showed a coincidence of fish detections in areas with turbulence intensities between 0.6 and 0.8, which may be an indication that the fish are holding in these areas to reduce energy expenditure during migration. A high proportion of the radio-tagged salmon were observed in the tailrace area (a median of 21 days between their first and last detection), indicating that the salmon are delayed in their upstream migration by the attraction to the tailrace in this area. The overall data on fish behavior in the tailrace led us to suggest a location for a new fishway where the fish aggregation was most pronounced. The number of detections from either technology had similar distributions over the tailrace, suggesting that the results are comparable. Thus, the split beam echo sounder can preferably be used to investigate which location is most appropriate for locations of entrances to new fishways since many more individual fishes are covered by this method compared to telemetry. Furthermore, there is no need to handle the fish in the echo sounding studies as is required in telemetry studies.     

Note on the determination of the best-fitting plane for a given set of directions

Summary Using Lagrange's multiplicator, a least-squares solution for the position of the plane that is in best accord with a finit number of directions is derived. Reference is made to a seismo-tectonic problem to which the solution can be applied.     

On a method for estimating the shape of a gravitationally and magnetically disturbing body

Summary The demagnetisation depends on the shape of the magnetised body. Here we investigate the possibility of calculating the shape of the magnetised body by means of the demagnetisation. It can be done if the gravity field and the induced magnetic field of a body with constant susceptibility and density are known. As the method is approximative it is not restricted just to bodies with a 2nd degree surface, but can be applied to all bodies, for which the demagnetisation can be regarded as constantly dependent on the direction. This means, with certain approximation, all bodies that are homogeneously magnetised, but not in the direction of the magnetising field due to demagnetisation.

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Zusammenfassung Die Demagnetisierung hängt von der Gestalt des magnetisierten Körpers ab. Hier soll untersucht werden, inwieweit es möglich ist, aus der Demagnetisierung Rückschlüsse über die Gestalt des magnetisierten Körpers zu ziehen. Dazu besteht die Möglichkeit, wenn das Gravitationsfeld und das induzierte Magnetfeld eines Körpers mit konstanter Dichte und Suszeptibilität gegeben sind. Da die Methode approximativ ist, ist sie nicht auf Körper mit Oberfläche 2ten Grades beschränkt, sondern sie kann in allen Fällen angewandt werden, in denen die Demagnetisierung als konstant richtungsabhängig angesehen werden kann. Dies bedeutet mit einer gewissen Approximation alle Körper, die homogen magnetisiert sind, aber infolge der Entmagnetiseerung nicht in der Richtung des magnetisierenden Feldes.

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