A mise‐à‐la‐masse study of the Cavendish Geophysical Test Site

Geophysics ◽  
1983 ◽  
Vol 48 (9) ◽  
pp. 1252-1257 ◽  
Author(s):  
L. Mansinha ◽  
C. J. Mwenifumbo
Keyword(s):  
Potential Field ◽  
Test Site ◽  
Drill Hole ◽  
Mineral Deposit ◽  
Current Electrode ◽  
Underground Openings ◽  
Mineralized Zone ◽  
Electrical Prospecting ◽  
Drill Holes ◽  
A Current

The mise‐à‐la‐masse method of electrical prospecting is used when a conductive, mineralized zone has already been located. A current electrode is placed directly in the mineralized zone, and the resulting potential field is mapped on the surface or in the subsurface via drill holes or underground openings. The potential field reflects the shape, size, and orientation of the mineral deposit. A field study of this method was carried out at the Cavendish Geophysical Test Site in Ontario, Canada. Two vein‐type mineralized bodies, zone A and zone B, are known to exist at the site. Drill holes were used to implant a current electrode in each of the veins and surface potentials were measured. The extension of the two zones in the strike direction was established with the resulting mise‐à‐la‐masse potential profiles. However, no electrical continuity between zones A and B could be discerned, indicating that the veins are not connected at depth. The dip of zone A appears to be toward the west, contrary to that inferred from the drill hole logs. The measured potentials are influenced by the mutual proximity of the far current and potential electrodes as well as by the location of the electrodes with reference to the local geologic structure.

PRECISE MEASUREMENT OF DEEP ELECTRICAL ANOMALIES

Geophysics ◽  
1944 ◽  
Vol 9 (4) ◽  
pp. 494-539 ◽  
Author(s):  
Thomas S. West ◽  
Clarence C. Beacham
Keyword(s):  
Precise Measurement ◽  
Oil And Gas ◽  
Depth Resolution ◽  
Lateral Variation ◽  
Current Electrode ◽  
Subsurface Zones ◽  
Electrical Prospecting ◽  
Direct Location ◽  
A Current ◽  
Made In

A method of electrical prospecting has been developed in which the deleterious effects of superficial inhomogeneities in resistivity are eliminated. An electrode configuration is used consisting of a current electrode at “infinity,” a pair of current electrodes with a constant separation of a few hundred feet which are used alternately, and a pair of potential electrodes with a constant separation of a few hundred feet, collinear with the pair of current electrodes, and at a distance from them which is varied to secure depth resolution. It is demonstrated that superficial influences are eliminated by forming the resistivity increment, the ratio between apparent resistivity determined by use of the closer current electrode of the alternate pair and that determined by use of the farther current electrode of the alternate pair. It is also demonstrated that the area explored is below a point approximately half‐way between the alternate pair of current electrodes. Resistivity increment curves, called Resistologs by the authors, can be correlated from station to station, and after they are correlated the lateral variation in the electrical properties of selected subsurface zones can be studied. As a result of the latter characteristic of the measurements, a possibility exists for the direct location of oil and gas, observational evidence for which is presented. The results of surveys made in Hart County, Kentucky, and in the Sam Fordyce, Seven Sisters, Pettus, Branyon, Dunlap, Oakville, and Rhode Ranch fields of Southwest Texas are displayed.

ANALYTIC MODELS FOR THE INTERPRETATION OF ELECTRICAL SURVEYS USING BURIED CURRENT ELECTRODES

Geophysics ◽  
1973 ◽  
Vol 38 (3) ◽  
pp. 513-529 ◽  
Author(s):  
Donald D. Snyder ◽  
Richard M. Merkel
Keyword(s):  
Apparent Resistivity ◽  
Three Dimensional ◽  
Drill Hole ◽  
Surface Electrode ◽  
Sphere Model ◽  
Current Electrode ◽  
Anomaly Pattern ◽  
Lateral Offset ◽  
Analytic Models ◽  
A Current

The IP response and the apparent resistivity resulting from a buried current pole in the presence of a stratigraphic target and a three‐dimensional target have been studied. The targets were modeled using a layered model to simulate the stratigraphic target and a buried sphere model to simulate the three‐dimensional target. The results show that there is a substantial increase in the response of the target measured at the surface for current electrode depths of greater than half the depth to the top of the target. A larger anomalous response is of particular importance when dealing with deeply buried targets from which little or no response is measured using conventional surface electrode methods. Furthermore, the results indicate that a survey around a drill hole containing a current electrode can be used to outline mineralization in the immediate vicinity of the drill hole. Some empirical observations resulting from our study are presented which relate the lateral offset of the target from the drill hole and its depth to characteristics of the anomaly pattern as measured on the surface.

PATTERNS OF GASTROPOD MOLLUSK PREDATION ON BIVALVE MOLLUSKS ALONG THE UPPER TEXAS GULF COAST

2018 ◽  
Vol 70 (1) ◽  
Author(s):  
Serena J. Randolph ◽  
Alan D. Maccarone
Keyword(s):  
Shell Thickness ◽  
Prey Species ◽  
Gulf Coast ◽  
Prey Selection ◽  
Drill Hole ◽  
The United States ◽  
Hole Diameter ◽  
Bivalve Mollusks ◽  
Collection Site ◽  
Drill Holes

Abstract Predation on bivalve mollusks by gastropod mollusks is common in coastal regions of the United States; however, few previous studies have examined whether drilling gastropods exhibit prey selection. In 2016, shells with small holes drilled by as many as two gastropod predators were collected at three sites separated by 30 km along the Texas Upper Gulf Coast on the Bolivar Peninsula (29° 40′N, 94° 90′W). The likeliest predators in these waters are the southern oyster drill (Stramonita haemastoma Linnaeus 1767) and the moon snail (Neverita duplicate Say 1822). Collected shells were identified to species and measurements were taken to examine statistical relationships between predators and prey species. These measurements included drill-hole diameter, shell thickness, drill-hole completeness, number of drill attempts, and collection site. Across the three locations, 17 different species of shells with drill holes were collected; of these, we focused on the ten most abundant species (n = 277 shells). The sample showed high variation in drill-hole diameter, shell thickness, and drill-hole completeness. Both the total number of holes and mean drill-hole diameter differed significantly among prey species (ANOVA, both P < 0.0001). In addition, drill-hole diameter correlated directly with prey shell thickness (P < 0.0001). Shells whose drill holes were complete were significantly thinner than shells with incomplete holes (P < 0.0001). Mean prey shell thickness, mean drill-hole diameter, and mean number of drill holes all differed significantly by collection site (all P < 0.0001). Ecological and morphological implications related to gastropod predation on mollusks are discussed.

scholarly journals Fluoride removal using electrocoagulation technique

2021 ◽  
Vol 877 (1) ◽  
pp. 012047
Author(s):  
Hind M. Ewadh ◽  
Mustafa J. Al Imari ◽  
Sabrean F. Jawad ◽  
Hayfaa A. Mubarak
Keyword(s):  
Severe Disease ◽  
Electrical Current ◽  
Electrode Spacing ◽  
Polluted Water ◽  
Fluoride Removal ◽  
Acidic Environment ◽  
Current Electrode ◽  
The Past ◽  
The Impact ◽  
A Current

Abstract A modest quantity of fluoride can increase the mineralization of teeth and reduce their cavities. But the presomerence of fluoride in excess in water can lead to severe disease infertility. In the past few decades, scientists have thus been preoccupied with developing ways to reduce sewage fluoride concentrations and reduce their effects on human health. The present study is aimed at using the technology of electrocoagulation to remove fluoride from polluted water. Tests have been done to examine the elimination of fluoride with a rectangular electrocoagulation cell and examine the impact of the experimental aspects on fluoride extraction, specifically electrical current, electrode spacing, and pH. The authors found that 93% of the fluoride has been extracted using 5mm spaced electrodes with a current density of 2 mA/cm2 and a level of pH of 7 from the polluted water after 20 min of processing. Experimental factors considerably impact the efficacy of fluoride removal. In the acidic environment, greater effectiveness of fluoride removal is being attained. The elimination effectiveness depends directly on the electric current, whereas the distance between poles is adversely linked to fluoride elimination.

Large Drill Holes Are Still Present in the Long Term After Arthroscopic Bankart Repair With Absorbable Tacks: An 18-Year Randomized Prospective Study

2020 ◽  
Vol 48 (8) ◽  
pp. 1865-1872
Author(s):  
Christina Chrysanthou Constantinou ◽  
Ninni Sernert ◽  
Lars Rostgård-Christensen ◽  
Jüri Kartus
Keyword(s):  
Study Groups ◽  
Drill Hole ◽  
Ct Images ◽  
Bankart Repair ◽  
Plain Radiographs ◽  
Arthroscopic Bankart Repair ◽  
Absorbable Tacks ◽  
Drill Holes

Background: Studies have demonstrated the development of an osseous reaction at the drill sites of anchors after arthroscopic shoulder surgery. Purpose: To investigate the drill-hole size at 18 years after arthroscopic Bankart repair using either fast polygluconate acid (PGA) or slow polylevolactic acid (PLLA) absorbable tacks and to compare the functional outcomes and development of osteoarthritis. Study design: Randomized controlled trial; Level of evidence, 2. Methods: 40 patients with unidirectional anterior shoulder instability, treated with arthroscopic Bankart repair, were randomized into the PGA group (n = 20) or the PLLA group (n = 20). Plain radiographs of both shoulders, as well as computed tomography (CT) images of the operated shoulder, were used to evaluate the drill-hole size, volume, and degenerative changes. Functional outcomes were assessed by use of the Rowe score, Constant score, and Western Ontario Shoulder Instability (WOSI) index. Results: Of the 40 patients, 32 patients returned for the follow-up (15 PGA and 17 PLLA). No significant differences were found in the population characteristics between the study groups. The mean follow-up time was 18 years for both groups. No significant differences were seen in range of motion, strength in abduction, or Constant, Rowe, and WOSI scores between the groups. Recurrence rate was 33% in the PGA group and 6% in the PLLA group during the follow-up period ( P = .07). The drill-hole appearance on plain radiographs (invisible/hardly visible/visible/cystic) was 11/2/2/0 and 6/5/5/1 for the PGA and PLLA groups, respectively ( P = .036). The mean ± SD drill-hole volume as estimated on CT images was 89 ± 94 and 184 ± 158 mm3 in the PGA and PLLA groups, respectively ( P = .051). Degenerative changes (normal/minor/moderate/severe) on plain radiographs were 7/4/4/0 and 3/8/5/1 for the PGA and PLLA groups, respectively ( P = .21), and on CT images were 5/7/3/0 and 2/6/6/3 for the PGA and PLLA groups, respectively ( P = .030). Conclusion: This long-term follow-up study demonstrated that the PLLA group had significantly more visible drill holes than the PGA group on plain radiographs. However, this difference was not evident on CT imaging, with both groups having several visible cystic drill holes and a substantial drill-hole volume defect. No significant differences were found between the study groups in terms of clinical outcomes.

The application of the mise-a-la-masse electrical technique in Greenstone belt gold exploration

1989 ◽  
Vol 20 (2) ◽  
pp. 113
Author(s):  
L.G.B.T. Polomé
Keyword(s):  
Greenstone Belt ◽  
Electrical Potential ◽  
Gold Deposits ◽  
Iron Formation ◽  
Banded Iron Formation ◽  
Current Electrode ◽  
Barberton Greenstone Belt ◽  
A Current ◽  
Ore Zones ◽  
Gold Bearing

Most of the gold deposits in the Barberton Greenstone belt of South Africa are relatively small and in structurally complex geological areas.The mise-a-la-masse electrical technique, where a current electrode is earthed in a mineralised zone, was used on one of our exploration projects consisting of a sulphides/gold-bearing carbonaceous banded iron formation within a succession of mafic, ultramafic and sedimentary rocks. The technique was successful in delineating individual mineralised units within a broad lithological sequence. During the survey, electrical potential measurements were recorded on surface, in underground drives and in twenty five boreholes. Measurements were also repeated by earthing the mineralised zone in a number of boreholes. Major discontinuities were recognised within the ore zones and used to interpret geological structures. These were then used to define specific units for ore reserve calculations and the application of selected mining techniques.

Investigation of Drill Hole Quality of Multi-Layer PWBs for High Current Capacity

2007 ◽  
Author(s):  
Eiichi Aoyama ◽  
Toshiki Hirogaki ◽  
Keiji Ogawa ◽  
Kenichi Mori ◽  
Yuusuke Itagaki
Keyword(s):  
Copper Foil ◽  
Drill Hole ◽  
Foil Thickness ◽  
Electronic Systems ◽  
Hole Quality ◽  
Large Current ◽  
Drill Holes ◽  
Objective Variable ◽  
Chip Load ◽  
Through Hole

Recently, as a result of changes in the automotive industry, a large number of electronic systems have been installed in cars. The thickness of the copper foil used for printed wiring boards (PWBs) has tended to increase in response to the large current capacity required for such electronic equipment. Therefore, the nail head generated in the inner layer copper foil was examined with respect to the influence of the thickness of the copper foil on the through-hole quality. In the present study, the size of the nail head generated in the copper foil after drilling a through hole was used as the objective variable. The explaining variables included drill wear, frequency, feed rate, chip load, drill temperature, copper foil thickness, copper foil cutting distance, and number of drill holes. We investigated the relationships between these explaining variables and the objective variable and found that the copper foil cutting distance was a very important parameter in generating nail heads. In addition, we found that the chip load is important for controlling nail head generation.

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