Model studies of electrical leak detection surveys in geomembrane‐lined impoundments

Geophysics ◽  
1988 ◽  
Vol 53 (11) ◽  
pp. 1453-1458 ◽  
Author(s):  
J. O. Parra ◽  
T. E. Owen
Keyword(s):  
Field Survey ◽  
Electrical Potential ◽  
Three Dimensional ◽  
Liquid Waste ◽  
Finite Size ◽  
Leak Detection ◽  
Electrode Spacing ◽  
Model Studies ◽  
Optimum Selection ◽  
Selection Of

Pole‐dipole array electrical potential distributions are calculated for a geomembrane‐lined liquid impoundment having single or multiple leaks. A three‐dimensional numerical model is employed to represent a small circular leak in the highly resistive plastic liner. The liquid waste material, the liner, and the soil under the impoundment are simulated by infinite horizontal layers, with approximate corrections for the finite size of the impoundment. Parametric curves for a single leak show that with optimum selection of electrode spacing and positioning and other field survey parameters, leaks can be detected effectively. To identify and resolve the presence of a cluster of leaks, the potential measurements must be made close to the liner and the detector dipole spacing must be smaller than the separation of the leaks. The results also indicate that the survey speed may be increased when portable leak detection equipment employing a vertical dipole detector is used.

Optimum design of gripper jaws for tapered components

Robotica ◽  
1990 ◽  
Vol 8 (3) ◽  
pp. 223-230 ◽  
Author(s):  
D.T. Pham ◽  
M.J. Nategh
Keyword(s):  
Optimum Design ◽  
Three Dimensional ◽  
Taper Angle ◽  
Planar Curves ◽  
Optimum Selection ◽  
Wide Range ◽  
Different Diameters ◽  
Selection Of

SUMMARYFor ease of manufacture, axisymmetric components produced by processes such as forging, casting and moulding are often designed with a taper angle. This paper presents a family of devices for handling such components by their tapered portion. The devices are essentially finger tips, or jaws, to be fitted to standard scissor-type robot grippers. The jaws possess a three-dimensional profile constructed as a stack of v-shaped planar curves. The special jaw profile enables components of different diameters and taper angles to be gripped concentrically without calling for complex movements to reposition the gripper. The equations describing two categories of profile are derived and the optimum selection of profile parameters to yield compact jaws to grip components of a wide range of dimensions is discussed in the paper.

Three‐dimensional model results for an electrical hole‐to‐surface method: Application to the interpretation of a field survey

Geophysics ◽  
1988 ◽  
Vol 53 (1) ◽  
pp. 85-103 ◽  
Author(s):  
D. Le Masne ◽  
C. Poirmeur
Keyword(s):  
Field Survey ◽  
Current Source ◽  
Electrical Potential ◽  
Three Dimensional ◽  
Electrical Parameters ◽  
Three Dimensional Model ◽  
Borehole Geophysics ◽  
Homogeneous Half Space ◽  
Surface Method ◽  
Three Dimensional Models

An important objective of borehole geophysics is to maximize information about inhomogeneities in the vicinity of existing boreholes. Three‐dimensional models (parallelepipedic inhomogeneities in a homogeneous half‐space) are used here to characterize the responses of an electrical hole‐to‐surface method ELECENT (ELECtrode ENTerrée) where conductive or resistive inhomogeneities (orebodies) occur in the vicinity of a borehole. Two types of surface measurements are carried out simultaneously at each station: electrical potential V (as in mise à la masse), and associated electrical field E. These two measured parameters give rise to three other parameters, two apparent resistivities (one for each V and E case) and another parameter quantifying the orientation of the E field. The influence of various geometrical and electrical parameters (such as the horizontal and vertical distances between the current source, the stations, and the inhomogeneity, and the size and resistivity of the inhomogeneity) on the five parameters above appears to be important. Values and positions of the extrema of these five parameters are characteristic of the geometrical and electrical parameters of the models. The orientation of the E field, for instance, is found to be critical to determining the shape of the inhomogeneity and its depth relative to the current source. The theoretical results obtained are used to interpret a field survey carried out around a borehole at the Beauvain prospect in France. Field maps of the five parameters show characteristics similar to the models described in the theoretical part of the study.

Three‐dimensional modeling of a hole‐to‐hole electrical method: Application to the interpretation of a field survey

Geophysics ◽  
1988 ◽  
Vol 53 (3) ◽  
pp. 402-414 ◽  
Author(s):  
C. Poirmeur ◽  
G. Vasseur
Keyword(s):  
Field Survey ◽  
Electrical Potential ◽  
Three Dimensional ◽  
Direct Calculation ◽  
Electrical Measurements ◽  
Injection Hole ◽  
Electrical Method ◽  
Three Dimensional Modeling ◽  
Dimensional Modeling ◽  
Different Shapes

Hole‐to‐hole electrical measurements can be used to localize or define the extension of conductive bodies whether or not they are penetrated by the holes. Two promising applications of this electrical method are the optimization of mining boreholes and the delineation of fractures. Although no particular problem arises in the instrumentation of a hole‐to‐hole electrical array, the interpretation of the results has proven to be difficult. A program has been developed to compute the electrical potential caused by direct current injection in an inhomogeneous half‐space (three‐dimensional bodies embedded within a layered earth). This program allows computation of the responses of most classical electrical arrays. It is based on calculation of a disturbance potential and on resolution of a Fredholm integral equation. The modeling program is used to define the apparent‐resistivity type responses of a hole‐to‐hole pole‐pole electrical configuration for different shapes and locations of bodies in the vicinity of the boreholes. To obtain a synthetic representation, the results are plotted on a plane where the X-axis corresponds to the depth in the measuring hole and the Y-axis corresponds to the depth in the injection hole. This representation seems to be particularly convenient for the electrical configuration examined here. A detailed study of simple geometrical models has yielded interpretation rules which have been applied to the qualitative interpretation of a field survey carried out at the mining prospect of SALAU (France). The program is then applied to this interpretation to check and confirm it, by direct calculation of the response corresponding to the model.

scholarly journals Optimum Selection of Variable Pitch for Chatter Suppression in Face Milling Operations

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 112 ◽  
Author(s):  
Alex Iglesias ◽  
Zoltan Dombovari ◽  
German Gonzalez ◽  
Jokin Munoa ◽  
Gabor Stepan
Keyword(s):  
Removal Rate ◽  
Face Milling ◽  
Heavy Duty ◽  
Variable Pitch ◽  
Thin Walls ◽  
Chatter Suppression ◽  
Milling Operations ◽  
Optimum Selection ◽  
Cutting Capacity ◽  
Selection Of

Cutting capacity can be seriously limited in heavy duty face milling processes due to self-excited structural vibrations. Special geometry tools and, specifically, variable pitch milling tools have been extensively used in aeronautic applications with the purpose of removing these detrimental chatter vibrations, where high frequency chatter related to slender tools or thin walls limits productivity. However, the application of this technique in heavy duty face milling operations has not been thoroughly explored. In this paper, a method for the definition of the optimum angles between inserts is presented, based on the optimum pitch angle and the stabilizability diagrams. These diagrams are obtained through the brute force (BF) iterative method, which basically consists of an iterative maximization of the stability by using the semidiscretization method. From the observed results, hints for the selection of the optimum pitch pattern and the optimum values of the angles between inserts are presented. A practical application is implemented and the cutting performance when using an optimized variable pitch tool is assessed. It is concluded that with an optimum selection of the pitch, the material removal rate can be improved up to three times. Finally, the existence of two more different stability lobe families related to the saddle-node and flip type stability losses is demonstrated.

scholarly journals A NEW APPROACH TO DYNAMIC FINITE-SIZE SCALING

2003 ◽  
Vol 14 (07) ◽  
pp. 945-954 ◽  
Author(s):  
MEHMET DİLAVER ◽  
SEMRA GÜNDÜÇ ◽  
MERAL AYDIN ◽  
YİĞİT GÜNDÜÇ
Keyword(s):  
Three Dimensional ◽  
Finite Size ◽  
Taylor Series Expansion ◽  
Scaling Behavior ◽  
Dynamic Scaling ◽  
Finite Size Scaling ◽  
New Approach ◽  
Size Scaling ◽  
Dynamic Exponent ◽  
Good Agreement

In this work we have considered the Taylor series expansion of the dynamic scaling relation of the magnetization with respect to small initial magnetization values in order to study the dynamic scaling behavior of two- and three-dimensional Ising models. We have used the literature values of the critical exponents and of the new dynamic exponent x0 to observe the dynamic finite-size scaling behavior of the time evolution of the magnetization during early stages of the Monte Carlo simulation. For the three-dimensional Ising model we have also presented that this method opens the possibility of calculating z and x0 separately. Our results show good agreement with the literature values. Measurements done on lattices with different sizes seem to give very good scaling.

Mechanism of the Transition From In-Plane Buckling to Helical Buckling for a Stiff Nanowire on an Elastomeric Substrate

2016 ◽  
Vol 83 (4) ◽  
Author(s):  
Youlong Chen ◽  
Yong Zhu ◽  
Xi Chen ◽  
Yilun Liu
Keyword(s):  
High Performance ◽  
Three Dimensional ◽  
Stretchable Electronics ◽  
Buckling Mode ◽  
Design And Optimization ◽  
Out Of Plane ◽  
Plane Direction ◽  
Plane Displacement ◽  
Helical Buckling ◽  
Selection Of

In this work, the compressive buckling of a nanowire partially bonded to an elastomeric substrate is studied via finite-element method (FEM) simulations and experiments. The buckling profile of the nanowire can be divided into three regimes, i.e., the in-plane buckling, the disordered buckling in the out-of-plane direction, and the helical buckling, depending on the constraint density between the nanowire and the substrate. The selection of the buckling mode depends on the ratio d/h, where d is the distance between adjacent constraint points and h is the helical buckling spacing of a perfectly bonded nanowire. For d/h > 0.5, buckling is in-plane with wavelength λ = 2d. For 0.27 < d/h < 0.5, buckling is disordered with irregular out-of-plane displacement. While, for d/h < 0.27, buckling is helical and the buckling spacing gradually approaches to the theoretical value of a perfectly bonded nanowire. Generally, the in-plane buckling induces smaller strain in the nanowire, but consumes the largest space. Whereas the helical mode induces moderate strain in the nanowire, but takes the smallest space. The study may shed useful insights on the design and optimization of high-performance stretchable electronics and three-dimensional complex nanostructures.

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