Effect of Polianthes tuberosa (Amaryllidaceae) on the Reproduction and Biochemical Parameters in the Ovotestis of Snail Lymnaea acuminata (Mollusca,Pulmonata)     

K. Singh  V. K. Singh  D. K. Singh 《洁净——土壤、空气、水》1999,27(1):32-37

The present study elucidates the effect of powder of Polianthes tuberosa bulb and its sapogenins tigogenin and hecogenin on the reproduction of the snail Lymnaea acuminata. It has been reported that the two sapogenins tigogenin and hecogenin caused a significant reduction in fecundity, hatchability, and survival of young snails. Exposure to sublethal concentration caused a small but significant reduction in protein, amino acids, nucleic acids, and phosphatase activities in gonadal tissue of treated snails. Withdrawal after 7 days indicates that the effect of powder of P. tuberosa bulb, tigogenin, and hecogenin on the reproduction and different biochemical parameters is reversible.  相似文献   

Spatial constrained inverse rock physics modelling   总被引：1，自引：0，他引：1       下载免费PDF全文

Erling H. Jensen  Tor Arne Johansen 《Geophysical Prospecting》2015,63(1):183-191

Predicting reservoir parameters, such as porosity, lithology, and saturations, from geophysical parameters is a problem with non‐unique solutions. The variance in solutions can be extensive, especially for saturation and lithology. However, the reservoir parameters will typically vary smoothly within certain zones—in vertical and horizontal directions. In this work, we integrate spatial correlations in the predicted parameters to constrain the range of predicted solutions from a particular type of inverse rock physics modelling method. Our analysis is based on well‐log data from the Glitne field, where vertical correlations with depth are expected. It was found that the reservoir parameters with the shortest depth correlation (lithology and saturation) provided the strongest constraint to the set of solutions. In addition, due to the interdependence between the reservoir parameters, constraining the predictions by the spatial correlation of one parameter also reduced the number of predictions of the other two parameters. Moreover, the use of additional constraints such as measured log data at specific depth locations can further narrow the range of solutions.  相似文献   

Joint parameter estimation from magnetic resonance and vertical electric soundings using a multi‐objective genetic algorithm     

İrfan Akca  Thomas Günther  Mike Müller‐Petke  Ahmet T. Başokur  Ugur Yaramanci 《Geophysical Prospecting》2014,62(2):364-376

Magnetic resonance sounding (MRS) has increasingly become an important method in hydrogeophysics because it allows for estimations of essential hydraulic properties such as porosity and hydraulic conductivity. A resistivity model is required for magnetic resonance sounding modelling and inversion. Therefore, joint interpretation or inversion is favourable to reduce the ambiguities that arise in separate magnetic resonance sounding and vertical electrical sounding (VES) inversions. A new method is suggested for the joint inversion of magnetic resonance sounding and vertical electrical sounding data. A one‐dimensional blocky model with varying layer thicknesses is used for the subsurface discretization. Instead of conventional derivative‐based inversion schemes that are strongly dependent on initial models, a global multi‐objective optimization scheme (a genetic algorithm [GA] in this case) is preferred to examine a set of possible solutions in a predefined search space. Multi‐objective joint optimization avoids the domination of one objective over the other without applying a weighting scheme. The outcome is a group of non‐dominated optimal solutions referred to as the Pareto‐optimal set. Tests conducted using synthetic data show that the multi‐objective joint optimization approximates the joint model parameters within the experimental error level and illustrates the range of trade‐off solutions, which is useful for understanding the consistency and conflicts between two models and objectives. Overall, the Levenberg‐Marquardt inversion of field data measured during a survey on a North Sea island presents similar solutions. However, the multi‐objective genetic algorithm method presents an efficient method for exploring the search space by producing a set of non‐dominated solutions. Borehole data were used to provide a verification of the inversion outcomes and indicate that the suggested genetic algorithm method is complementary for derivative‐based inversions.  相似文献   

草原生态系统模式中参数不确定性导致的模拟结果不确定性研究   总被引：1，自引：1，他引：0  

谢东东  孙国栋  邵爱梅  穆穆 《气候与环境研究》2013,18(3):375-386

基于五变量草原生态系统理论模式,应用与参数有关的条件非线性最优扰动(CNOP-P)方法,探讨了由参数不确定性导致的草原生态系统模式模拟结果的不确定性问题。参数的不确定性可能来源于观测和（或）对物理过程描述等的不确定性。选取了五变量草原生态系统模式中具有物理意义的32个模式参数进行数值试验。试验结果表明,对所考察的32个模式参数,在一定的不确定性和给定的优化时刻范围内,单独优化每个参数所得CNOP-Ps的联合模态与同时优化32个参数所得CNOP-P的模态并不相同。比较了上述两类参数误差以及随机参数误差对草原生态系统模拟的差异。随机参数误差与上述优化方法所得参数误差的不确定性范围大小相同。数值结果表明,同时优化32个参数所得 CNOP-P 类型参数误差使得草原生态系统模拟的不确定性程度最大。这种影响表现在使得草原生态系统转变为沙漠生态系统,或者使得草原生态系统转变为具有更多生草量的草原生态系统。上述数值结果不依赖于优化时间和参数不确定性程度的大小。这些数值结果建议我们应当考虑多参数的非线性相互作用来研究草原生态系统模式模拟的不确定性问题,并且揭示出CNOP-P方法是讨论上述问题的一个有用的工具。  相似文献   

A Dynamical Statistical Model for Prediction of a Tropical Cyclone     

S. K. Roy Bhowmik  S. D. Kotal 《Marine Geodesy》2013,36(4):412-423

A dynamical statistical method is applied for operational forecasting of the Bay of Bengal tropical cyclone “Nargis” of April–May 2008. The method consists of three forecast components, namely (a) analysis of Genesis Potential Parameter (GPP) and maximum potential intensity, (b) track prediction, and (c) 12 hourly intensity prediction for forecasts up to 72 hours. The results of the study showed that GPP could provide necessary predictive signal at early stages of development on the further intensification of the low pressure system into a tropical cyclone. The landfall forecast position errors by different operational numerical models (NWP) showed landfall position errors ranging from 10 km to 150 km and landfall time error ranges from 6 hours early to 6 hours delay. The dynamical statistical model is capable to provide 12 hourly nearly realistic intensity forecasts up to 60 hours of forecast.  相似文献   

Moveout approximation for horizontal transversely isotropic and vertical transversely isotropic layered medium. Part I: 1D ray propagation‡     

Igor Ravve  Zvi Koren 《Geophysical Prospecting》2010,58(4):577-597

Anisotropy in subsurface geological models is primarily caused by two factors: sedimentation in shale/sand layers and fractures. The sedimentation factor is mainly modelled by vertical transverse isotropy (VTI), whereas the fractures are modelled by a horizontal transversely isotropic medium (HTI). In this paper we study hyperbolic and non‐hyperbolic normal reflection moveout for a package of HTI/VTI layers, considering arbitrary azimuthal orientation of the symmetry axis at each HTI layer. We consider a local 1D medium, whose properties change vertically, with flat interfaces between the layers. In this case, the horizontal slowness is preserved; thus, the azimuth of the phase velocity is the same for all layers of the package. In general, however, the azimuth of the ray velocity differs from the azimuth of the phase velocity. The ray azimuth depends on the layer properties and may be different for each layer. In this case, the use of the Dix equation requires projection of the moveout velocity of each layer on the phase plane. We derive an accurate equation for hyperbolic and high‐order terms of the normal moveout, relating the traveltime to the surface offset, or alternatively, to the subsurface reflection angle. We relate the azimuth of the surface offset to its magnitude (or to the reflection angle), considering short and long offsets. We compare the derived approximations with analytical ray tracing.  相似文献   

Definition and interests of reciprocity and reciprocity gap principles for groundwater flow problems     

Nejla T. Hariga  Amel Ben Abda  Rachida Bouhlila  Jean-Raynald de Dreuzy 《Advances in water resources》2010

We introduce the reciprocity and reciprocity gap principles for flow problems in hydrogeology and illustrate their interest in addressing identification problems. The reciprocity principle is derived from mechanics and establishes for flow problems a relationship between different sets of forcing terms, including sources, sinks and boundary conditions, and the resulting head fields. The reciprocity gap principle compares different head fields resulting from the same forcing terms applied to different structures. We give general 2D expressions of the reciprocity and reciprocity gap principles for transient flow problems and give two examples of applications for the identification of transmissivity values and interfaces between different transmissivities. Identification capacities of the reciprocity and reciprocity gap principles yielding direct inversion methods could be used as initial guesses for more advanced inverse problem methodologies.  相似文献   

三维复电阻率电磁场正演研究     

许仕良  王丽妍  许权  李光波  焦紫晗 《云南地质》2009,28(3):299-306

将Cole—Cole模型表示的地下异常体各剖分单元复电阻率,引入到体积分方程求解均匀大地三维电磁场计算中,实现电偶源地面激发、接收复电阻率三维电磁场正演模拟。  相似文献   

Identification of diffusion parameters in a nonlinear convection–diffusion equation using the augmented Lagrangian method     

T. K. Nilssen  K. H. Karlsen  T. Mannseth  X.-C. Tai 《Computational Geosciences》2009,13(3):317-329

Numerical identification of diffusion parameters in a nonlinear convection–diffusion equation is studied. This partial differential equation arises as the saturation equation in the fractional flow formulation of the two-phase porous media flow equations. The forward problem is discretized with the finite difference method, and the identification problem is formulated as a constrained minimization problem. We utilize the augmented Lagrangian method and transform the minimization problem into a coupled system of nonlinear algebraic equations, which is solved efficiently with the nonlinear conjugate gradient method. Numerical experiments are presented and discussed. This work was partially supported by the Research Council of Norway (NFR), under grant 128224/431.  相似文献   

Robust Regulation of Alkalinity in Highly Uncertain Continuous Anaerobic Digestion Processes     

Víctor Alcaraz‐González  Fabián Azael Fregoso‐Sanchez  Hugo Oscar Mendez‐Acosta  Victor Gonzalez‐Alvarez 《洁净——土壤、空气、水》2013,41(12):1157-1164

In this paper, a multiple‐input multiple‐output (MIMO) model‐based robust control scheme is proposed for the indirect control of both total alkalinity and the ratio (intermediate alkalinity)/(total alkalinity) by regulating volatile fatty acid concentrations and strong ions concentration, while guaranteeing the so‐called operational stability in anaerobic digestion (AD) processes. The proposed MIMO regulator is an adaptive controller derived from an AD model which incorporates the physicochemical equilibrium of the system as well as the use of a robust interval observer to estimate key process bounds that are used in the computation of the control efforts. Numerical simulations were carried out for a number of operating conditions under the most uncertain scenarios. Results showed that the proposed multivariable control law is able to recover the system stability around a pre‐determined set point in the face of parameter uncertainty and load disturbances.  相似文献