The face‐current concept and its application to survey design in electrical exploration

Geophysics ◽  
2003 ◽  
Vol 68 (3) ◽  
pp. 900-910 ◽  
Author(s):  
Carlos A. Mendonça
Keyword(s):  
Survey Design ◽  
Electrical Potential ◽  
Ground Surface ◽  
Electrode Array ◽  
Homogeneous Half Space ◽  
The Face ◽  
Geoelectrical Structure ◽  
Dipole Sources ◽  
Conductivity Contrast

This paper presents a new method to identify the regions over a 3D geoelectrical structure that produce major contributions to the electrical potential established in response to a dc source at the ground surface. The measured potential is represented by a sum of a known primary potential (due to a homogeneous half space) plus an unknown potential caused by conductivity inhomogeneities. Because the primary potential is continuous everywhere, the interfaces with a conductivity contrast act as sources or sinks of currents in order to maintain the continuity of the current density related to the primary flux. These disturbing face currents are responsible for the generation of the secondary potential, and mapping them over a given structure allows us to assess the regions where the secondary potential is generated. In general, the face currents vanish away from the source according to the decay of the primary electric field. For this reason, deeper investigations can be expected when using pole sources because its primary field decays with the inverse of the squared distance, instead of the cubed distance as for dipole sources. For thin sheets, the polarization decay with distance is one order higher than that for large 3D bodies, which makes the detection of a sheet yet more difficult. The quantification of the total face current over the structure for different positions along a profile helps one choose the proper electrode array and determine its optimum length. This is done in two steps: (1) identification of the offset where the dc source provides the highest polarization (face current) on the targeted structure, and (2) determination of the array length by locating the potential electrodes closest to the region with the highest polarization. This second criterion came from an analogy between the face‐current and artificial current sources, where it is intuitively seen that the resulting potential is highest close to the source. The proposed survey design technique is applied to three models commonly used in electrical exploration: a shallow conductive heterogeneity, a buried contact, and a thin conductive sheet.

scholarly journals Determination of the Vertical Dimension and the Position of the Occlusal Plane in a Removable Prosthesis Using Cephalometric Analysis and Golden Proportion

2021 ◽  
Vol 11 (15) ◽  
pp. 6948
Author(s):  
Gabriele Cervino ◽  
Sergio Sambataro ◽  
Chiara Stumpo ◽  
Salvatore Bocchieri ◽  
Fausto Murabito ◽  
...  
Keyword(s):  
Vertical Dimension ◽  
Occlusal Plane ◽  
X Rays ◽  
Common Procedure ◽  
Lower Incisor ◽  
Golden Proportion ◽  
The Face ◽  
Removable Prosthesis ◽  
Edentulous Patients

The aim of this study is to demonstrate the use and the effectiveness of cephalometry and golden proportions analysis of the face in planning prosthetic treatments in totally edentulous patients. In order to apply this method, latero-lateral and posterior-anterior X-rays must be performed in addition to the common procedure. Two main concerns for totally edentulous patients are the establishment of the vertical dimension and the new position of the occlusal plane. The divine proportion analysis was carried out by the use of a golden divider. The prosthetic protocol was divided into three steps and a case was selected for better understanding. Referring to the golden relations, if the distance from the chin to the wing of the nose is 1.0, the distance from the nose to eye is 0.618. This proportion is useful and effective in determining the correct prosthetic vertical dimension. The incisal margin of the lower incisor must be positioned between Point A (A) and protuberance menti (Pm) according to the gold ratio 0.618 of the total height A-Pm. Posteriorly the occlusal plane must be placed 2 mm below the divine occlusal plane (traced from the incisal margin of lower incisors to Xi point). A prosthesis made in accordance with cephalometric parameters and divine proportions of the face helps to improve the patient’s aesthetics, function and social personality.

A disposable aptasensor based on a gold-plated coplanar electrode array for on-site and real-time determination of Cu2+

2021 ◽  
pp. 338991
Author(s):  
Haochen Qi ◽  
Xiaofan Huang ◽  
Jayne Wu ◽  
Jian Zhang ◽  
Fei Wang ◽  
...  
Keyword(s):  
Real Time ◽  
Electrode Array ◽  
Time Determination

Identification and determination of phenolic constituents in natural beverages and plant extracts by means of a coulometric electrode array system

1993 ◽  
Vol 632 (1-2) ◽  
pp. 111-117 ◽  
Author(s):  
Guido Achilli ◽  
Gian Piero Cellerino ◽  
Paul H. Gamache ◽  
Gian Vico Melzi d'Eril
Keyword(s):  
Plant Extracts ◽  
Electrode Array ◽  
Phenolic Constituents

scholarly journals Theoretical framework for estimating snow distribution through point measurements

2015 ◽  
Vol 9 (1) ◽  
pp. 1-44
Author(s):  
E. Trujillo ◽  
M. Lehning
Keyword(s):  
Snow Depth ◽  
Survey Design ◽  
Spatial Location ◽  
Theoretical Framework ◽  
Statistical Properties ◽  
Spatial Covariance ◽  
Sample Mean ◽  
Snow Properties ◽  
Survey Designs

Abstract. In recent years, marked improvements in our knowledge of the statistical properties of the spatial distribution of snow properties have been achieved thanks to improvements in measuring technologies (e.g. LIDAR, TLS, and GPR). Despite of this, objective and quantitative frameworks for the evaluation of errors and extrapolations in snow measurements have been lacking. Here, we present a theoretical framework for quantitative evaluations of the uncertainty of point measurements of snow depth when used to represent the average depth over a profile section or an area. The error is defined as the expected value of the squared difference between the real mean of the profile/field and the sample mean from a limited number of measurements. The model is tested for one and two dimensional survey designs that range from a single measurement to an increasing number of regularly-spaced measurements. Using high-resolution (~1 m) LIDAR snow depths at two locations in Colorado, we show that the sample errors follow the theoretical behavior. Furthermore, we show how the determination of the spatial location of the measurements can be reduced to an optimization problem for the case of the predefined number of measurements, or to the designation of an acceptable uncertainty level to determine the total number of regularly-spaced measurements required to achieve such error. On this basis, a series of figures are presented that can be used to aid in the determination of the survey design under the conditions described, and under the assumption of prior knowledge of the spatial covariance/correlation properties. With this methodology, better objective survey designs can be accomplished, tailored to the specific applications for which the measurements are going to be used. The theoretical framework can be extended to other spatially distributed snow variables (e.g. SWE) whose statistical properties are comparable to those of snow depth.

scholarly journals Kemampuan Lulusan Sekolah Tinggi Pariwisata Ampta Dalam Menghadapi Persaingan Di Dunia Kerja

Media Wisata ◽  
2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Sri Larasati
Keyword(s):  
Communication Skill ◽  
Total Population ◽  
Sampling Technique ◽  
Regression Equations ◽  
Test Results ◽  
A Value ◽  
The Face ◽  
Job Competition ◽  
Sampling Approach

The purpose of this research is to know wtether knowledge, skill, responsiveness and communication skill influence in job competition for graduate student from Sekolah Tinggi Pariwisata AMPTA. The population in this study are student pf Sekolah Tinggi Pariwisata SMPTA that graduated in 2013 until 2016, the total population in this studt is 702 and 200 respondents who have worked taken as samples, samples were taken with non probability sampling technique and accidental sampling approach. Sampling approach using regression equations obtained results that through test results F (regression analysis jointly) may note that the value of F = 147.104 count with the significance of 0.000 < 0.05. The test results of the test F reinforced with testing the determination of the coefficient that shows the value of 74.6%) (0.746. From Test t (partially) can result in variable knowledge with a value of t = 3,173 and significance of the value 0002 < 0.05, variable skill with a value of t = 2,949 and value the significance of 0.004 < 0.05, variable attitude with a value of t = 2,688 and value the significance of 0.008 < 0.05, variable communication skill with a value of t = value and significance of 4,497 0000 < 0.05. From the above results can be known that the hypothesis posed was not proven in other words that all of these variables can be said to have a positive and significant effect simultaneously as well as partial toward the ability of STP graduates AMPTA in the face of competition in the world of work

scholarly journals Liquefaction Susceptibility of an Earth Dam Foundation: A Case Study 

2021 ◽  
Author(s):  
Hatem karoui ◽  
Mounir Bouassida
Keyword(s):  
Ground Surface ◽  
Standard Penetration Test ◽  
Earth Dam ◽  
Sand Layer ◽  
Dam Foundation ◽  
Liquefaction Susceptibility ◽  
Numerical Predictions ◽  
Earth Embankment ◽  
Heterogeneous Foundation

Abstract Sidi El Barrak earth dam is a compacted earth embankment of height 28 m built in 1999 on a heterogeneous foundation with strong dominance of sandy formations. The dam foundation was subjected to several tests to predict its behavior against the liquefaction risk. Standard penetration test (SPT) results served to evaluate the liquefaction risk in an earthquake occurrence. This article, firstly, presents an interpretation of data collected from SPT tests. Determination of liquefaction risk resulted from the empirical methods proposed by Seed & Idriss, (1985) and Idriss & Boulanger, (2008). Obtained results by those methods showed that, for different earthquake magnitudes equal to 5.25, 6 and 6.75, the risk of liquefaction exists in the pure sand layer located between the ground surface and 15 m depth of the foundation of the earth dam. An UBC3D-PLM constitutive model was adopted for studying the numerical response of sand layer subjected to an earthquake of acceleration equal 0.2 g to estimate its liquefaction risk. Recorded SPT data and laboratory tests results served for the determination of geotechnical parameters of this model. From numerical predictions it revealed that the liquefaction risk is greater for an earthquake characterized by an acceleration equal 0.2g.

scholarly journals INVESTIGATION OF THE GEOMECHANICAL STATE OF SOFT ADJOINING ROCKS UNDER PROTECTIVE CONSTRUCTIONS

2021 ◽  
Vol 36 (4) ◽  
pp. 61-71
Author(s):  
Serhii Nehrii ◽  
Tetiana Nehrii ◽  
Oksana Zolotarova ◽  
Serhii Volkov
Keyword(s):  
Physical And Mechanical Properties ◽  
New Approach ◽  
Soft Rocks ◽  
The Face ◽  
Geomechanical State ◽  
Rock Mass Failure ◽  
The Stability ◽  
Seam Mining ◽  
Mine Roadways

The conditions of coal seam mining in the mines of Ukraine have been considered. The problem of conducting coal mining by longwalls in the conditions of soft adjoining rocks, which concerns the protection of mine roadways located near the face, has been revealed. In such conditions, the existing protective constructions are ineffective due to the fact that they yield and get pressed into the soft rocks of the footwall. This indicated the need for research into the geomechanical state of soft rocks of the footwall. According to the results of known studies on the mechanism of rock mass failure around roadways and the data of physical and mechanical properties of the coal mass, which is represented by soft rocks, the correlation dependence has been obtained, the use of which allowed for the determination of the parameters of the rock deformation diagram and the establishment of the stability criterion of footwall rocks under the protection means and stability conditions of the geotechnical system “protective construction – adjoining rocks.” They are the basis of a new approach to ensure the stability of the roadways, which are supported behind the faces, by controlling the stress state in the system “protective construction – adjoining rocks.” This may be the basis for the development of new methods of protecting roadways in conditions of soft adjoining rocks.

scholarly journals Cultism and Violence in Nigerian Universities: A Paradigm for Achieving Religious Academic Excellence

2019 ◽  
Vol 6 (2) ◽  
pp. 102
Author(s):  
Ushe Mike Ushe
Keyword(s):  
Moral Education ◽  
Survey Design ◽  
Daily Basis ◽  
Academic Excellence ◽  
University Campuses ◽  
Face To Face ◽  
The Face ◽  
Persistent Violence ◽  
The Government ◽  
Forms Of Violence

Nigerian universities and other institutions of higher learning have in recent times witnessed unprecedented insecurity, persistent violence and educational backdrop, leading to loss of many lives and properties worth millions of naira across the country. Part of the face out of this scourge is the prevailing case of cultism and other forms of violence in Nigerian universities and other higher educational institutions. This has resulted to gruesome arrest, expulsion and murder of many students on account of cult activities on the campuses and other forms of students’ violence which further exposed our universities to insecurity, ritual murders, drug abuse and use of dangerous weapons by cult groups, victimization and regime of terror against fellow students, lecturers, and anyone that stands in the ways of these cult groups on our campuses. This paper discusses the impacts of cultism and other forms of violence on university campuses in Nigeria as a search for achieving sustainable peace and academic excellence. To explore this change, the study employs survey design, questionnaires and face-to-face interviews in collecting data and analysis. The research findings have shown that cultism and other forms of violence are prevalence in Nigerian universities and have increased tremendously in recent decades, reoccurring almost on daily basis. The paper observed that students’ radical activism and union politics, incapability of university and state authorities to enforce minimum standard of students’ civil behaviors on campuses as well as rivalries between cult groups and the wider campus community has drastically affected educational or academic performance of students in contemporary Nigerian society. The paper recommends the restructuring of university educational policies and curriculum, provision of moral education and non-interference of the government and university authorities in the affairs of students’ union politics and activism.

scholarly journals Determination of Recent Movements of Lithosphere in Regions with Chemogenic Sediments on the Surface in the Dinarides Region

2014 ◽  
Vol 96 (1) ◽  
pp. 20-26
Author(s):  
Almin Đapo ◽  
Boško Pribičević ◽  
Lidija Špiranec
Keyword(s):  
Carbonate Rocks ◽  
Ground Surface ◽  
Tectonic Activity ◽  
Surrounding Area ◽  
Isostatic Equilibrium ◽  
Tectonic Movements ◽  
Chemical Sediments ◽  
Carbonate Deposits ◽  
Significant Mass

Abstract In the area of carbonate or karst Dinarides, besides the dominant carbonate rocks and subordinate clastics, in more places more significant mass of chemical sediments can be found, represented by gypsum and anhydrite. As chemical sediments are specifically lighter than overlying rocks, they have been, during the long geological history, trying to achieve isostatic equilibrium, or get out on the ground surface. In recent times, in areas with chemical sediments, a larger tectonic activity is noted than in the wider environment. This is certainly reflected in increased vertical and tangential displacements along major faults in relation to the surrounding area, which are built mainly of carbonate deposits. Determining the amount of movement of diapiric bodies, as absolute and relative, using the most modern surveying methods, precisely would assist the understanding of the tectonic movements and recent structural relations in a wider area

scholarly journals Phosphorus Speciation in Surface Waters by Ion Chromatography With High Resolution Mass Spectrometry Detection

2021 ◽  
Author(s):  
Vlastimil Packa
Keyword(s):  
Mass Spectrometry ◽  
Ion Chromatography ◽  
High Resolution Mass Spectrometry ◽  
Ground Surface ◽  
Analytical Determination ◽  
Water Quality Control ◽  
Accuracy Of Measurements ◽  
Total P ◽  
Inorganic And Organic

Phosphorus (P) containing compounds, depending on their origin, can enter freshwater systems in variety of forms. Utilization of bioavailable P, a key nutrient in living organisms, is a crucial factor in biological productivity in aquatic environment¹. An increase in the P concentration in water, resulting from both natural and anthropogenic processes, can lead to eutrophication and an excessive growth of vegetative biomass. Determination of organic and inorganic P species in ground, surface and waster is an important part of water quality control and monitoring². Analytical determination of P compounds, quantification, identification (Chapter 2) and P speciation process can be problematic due to P adsorption on storage containers, sulfate interference, presence of acid hydrolysable P species and colloidal matter, association of both inorganic and organic phosphates with iron, manganese and aluminum, biological uptake of P. Such processes have to be considered when designing an analytical procedure for analysis of P species. Analytical P compound separation by ion chromatography with mass spectrometry/Orbitrap technology for compound detection (Chapter 3) is a powerful technology with highly sensitive and selective properties capable of performing P speciation in one analytical run. Selectivity of the Orbitrap detector also allows for utilization of isotope dilution technique which can compensate for loss of P compounds during storage and transportation and thus increase accuracy of measurements and holding time of sample matrices. Analytical techniques used in the past were able to determine broad P-fractions, such as total P, total P or functional groups of inorganic and organic P compounds. Identification of variety of specific P-containing compounds of inorganic and organic origin by the methodology used in this thesis in combination with multivariate statistical analysis can be used to explain the large sets of intercorrelated analytical variables with a smaller set of independent variables (Chapter 4) and help in source identification in water pollution studies³.

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