MARINE ELECTRICAL RESISTIVITY METHOD

Open-File Report, 1984

A total of 19 Sen1umberger resistivity soundings and 3 resistivity gradient profiles were made to study the high-level water body beneath the Schofield plateau in central O'ahu. The soundings yield much detail on the thick weathered zone overlying unweathered rock over the entire area. They also delineate areas which are underlain by a conductor interpreted to be salt water saturated rock outside the high level aquifer. Mithin the aquifer, the basement conductor is not found. Secondarily, the results indicate that the aquifer may be impounded by buried ridges of the Waianae volcano.-2-Resistivity Investigation Kauahikaua & Shettigara Schofield, O'ahu Resistivity Investigation Kauahikaua & Shettigara Schofield, O'ahu DESCRIPTION OF RESISTIVITY TECHNIQUES USED Resistivity is one of the most useful geophysical properties on which to base ground water exploration because the resistivity of a rock varies with its water content and the quality of the contained water and because it is possible to determine the resistivities of deeply-buried rock units from surface measurements. Once the resistivity of the rock units are determined, gross physical properties like porosity, water quality, etc., can theoretically be estimated (Keller and Frischknecht, 1966). Resistivity methods are actually unique among surface geophysical methods in providing information concerning the presence and quality of water and are extensively used for determining the depth of fresh-salt water interfaces. In resistivity prospecting, electrical current is passed into the earth through two electrodes, designated A and B. The difference in potential between any two points can then be measured using two more electrodes, designated M and N. For the electrode configurations described in this report, the electrodes are arranged in the order AMNB in a straight line. From the relative locations of the electrodes, a correction or geometrical factor can be computed which, when multiplied by the ratio of potential difference divided by the current through electrodes A and B, would produce a value identical to any which is produced by any other electrode configuration over a homogeneous halfspace and which is corrected similarly. For a homogeneous halfspace, that value is equal to the resistivity of the halfspace. For the more general case, the value is called an 'apparent resistivity' and it is the field data to be interpreted. Data are gathered by moving the electrodes and remaking the measurements, in one of two modes sounding or profiling. Resistivity Investigation Kauahikaua & Shettigara Schofield, O'ahu '71 "7

Symposium on the …, 2002

In this paper, we describe an instrument system for performing continuous resistivity profiling in shallow freshwater and marine environments. Using a streamer cable containing 9 electrodes, the system continuously samples the dipole-dipole resistivity at n-spacings 1 through 6. The system can be installed aboard a variety of small inboard or outboard powered vessels in a few hours. Hand-held or marine GPS units provide location information that is recorded by a laptop computer. With this system, up to 40 line-km/day of dipole-dipole data have been collected. The resistivity data are merged with the GPS positions as a post-processing step. The final step in the post-processing is the inversion of overlapping segments of each profile using a 2-D smooth model. The inversions provide high resolution images of the geoelectric cross-section. The depth of investigation ranges from 20-30 m, with a 10 m dipole spacing. Over the last 4-years, we have performed surveys on the Ohio River, near Louisville, KY, on tidal estuaries and bays along the Atlantic coast in Delaware, Maryland, Virginia, and North Carolina, and in Tampa Bay, Florida. Data from these surveys will be used to illustrate the final deliverable from a survey.

2018

2017

Onshore applications of direct current resistivity (DCR) along shorelines suffer a short-circuit-like phenomenon due to electrical current flowing through a more conductive body of water rather than ground. Our study of the numerical simulation of DCR data with a three-dimensional forward model demonstrated that the apparent resistivity was reduced as a function of the sea depth and the distance of measurement site to the shoreline. Furthermore, it was concluded that the “marine effects” on DCR data (i.e. reduction in apparent resistivity) become nonnegligible as the ratio of half-electrode expansion (AB/2) to the distance to the shoreline is larger than one. The reduction in apparent resistivity reaches its highest levels as the ratio approaches ten. Our survey conducted along the coastal line of Northwest Turkey clearly showed that if the “marine effects” are left untreated, one- or two-dimensional inversion yields incorrect resistivities for underlying units and therefore undermines the credibility of survey results. In the paper suggestions are made to handle such situations

Terrestrial, Atmospheric and Oceanic Sciences, 2011

In contrast to marine sediments, because of large electrical resistivity anomalies found in sulfide deposits and methane hydrates, resistivity measurements such as marine towed electrical resistivity (MTER) might be a feasible method for discovering those natural minerals. To determine the feasibility of the MTER method we examined arrays consisting of a pole electrical dipole (PED), vertical electrical dipole (VED) and horizontal electrical dipole (HED). The VED array showed a maximum difference in electric fields of 36% and 105% in the resistive and conductive models, respectively, while the PED and HED arrays yielded worse results of around 13% to 19%, respectively. The VED array showed a higher difference in electric fields than both the HED and PED arrays in the two models. Therefore, we suggest that a VED array with a large electrical current would be most conducive leading to the discovery of such minerals during MTER surveys.

2021

Nombres Revista De Filosofia, 2012

SÉMINAIRE D’HISTOIRE ET MUSICOLOGIE “Normes, cultures, pouvoirs” Organisation scientifique : Claire Angotti, Bertrand Marceau et Marc Rigaudière Centre d’Études et de Recherche en Histoire Culturelle (CERHiC) Il est possible de participer à cette présentation à distance. Écrire à [email protected] pour recevoir le lien de connexion.

"Importa enunciar este hecho: el estudio psicoanalí-tico de la locura, sea cual fuere el significado de ésta, se realiza principalmente sobre la base del análisis de los llamados´casosllamados´casos fronterizos´…".-Winnicott (1963) A modo de introducción Las organizaciones fronterizas cuestionan las fronteras de nuestra disciplina, las fronteras del psicoanálisis actual. Hacen que nuestro método se interrogue, empujan a la polémica, al debate, despiertan dudas y alejamientos de certezas obturantes. Escribir sobre organizaciones fronterizas presupone de entrada navegar por aguas turbu-lentas, enfrentarse con aquellos puntos de extravío de la teoría y la clínica psicoanalítica que provocan inquietud y nos impulsan a la búsqueda de nuevas respuestas posibles ante un cúmulo de interrogantes. Los sujetos que nos consultan y que se sienten atravesados por las múltiples problemáti-cas que caracterizan a los borderline conmueven cualquier respuesta añejada y nos convocan así a retrabajar nuestro posicionamiento teórico-clínico. Son pacientes que nos incomodan y nos invitan a examinar nuestras inercias y a buscar ideas nuevas ya sea en lecturas o en intercambios con colegas Sabemos que el psicoanálisis nació y se desarrolló dentro de un marco social y cultural diferente del actual. Un marco que, entre otras cosas, estaba definido por la estabilidad en algunos planos, como el familiar. La mirada estaba dirigida hacia lo que sucedía puertas adentro, en la familia. Y, dentro de ese contexto, más ligado al encierro, se ubicaba el inte-rés por el complejo de Edipo, las histerias, la sexualidad infantil. Las neurosis ocupaban el centro de la escena y de los devaneos de nuestros colegas pioneros. Hoy estamos atravesados por las ausencias, por lo que falta. Ahora el centro está ocupa-do por las "patologías actuales", aquéllas ligadas a las problemáticas narcisistas entre las cuales están las organizaciones fronterizas. Recordemos también que desde el punto de vista epistemológico nos fuimos apartando de la impronta positivista que impregnaba a las ciencias de comienzos de siglo, con la fuerte búsqueda de objetividad que llevaba implícita. Hoy es habitual escuchar que se dejó de lado el discurso de las profundidades y ocupa su lugar el de las superficies. Que el sujeto alienado, víctima de la represión, fue cediendo lugar al sujeto fragmentado, asociado más a la idea de escisión. En el modelo de las profundidades se piensa en términos de histo-ria, de un proceso que implica la noción de tiempo. En el de las superficies impacta más el espacio, el lugar, o como dice Augé (1996) el no lugar. Algunos autores sostienen que las patologías de lo fronterizo son predominantes en la ac-tualidad. ¿Es esto efectivamente así? ¿Han abandonado realmente las neurosis el foco de la escena psicoanalítica? ¿Han cambiado nuestros pacientes o es que se ha ampliado nuestra escucha y el abanico de nuestras intervenciones, alojando de este modo padeci

El tratamiento de aguas y las plantas de tratamiento de agua son un conjunto de sistemas y operaciones unitarias de tipo físico, químico o biológico cuya finalidad es que a través de los equipamientos elimina o reduce la contaminación o las características no deseables de las aguas, bien sean naturales, de abastecimiento, de proceso o residuales.