Electrical modeling of the inhomogeneous invaded zone

Geophysics ◽  
1984 ◽  
Vol 49 (10) ◽  
pp. 1580-1585 ◽  
Author(s):  
D. Drahos
Keyword(s):  
Recursive Formula ◽  
Depth Of Invasion ◽  
Usual Model ◽  
Resistivity Profile ◽  
True Resistivity ◽  
Rock Model ◽  
Invaded Zone ◽  
The Many ◽  
Layer Problem

The ideal rock model in electrical well logging for prospecting hydrocarbon consists of three cylindrical layers characterized by homogeneous resistivities. The second layer of the model respresents the zone of invasion, where under real circumstances the resistivity is not constant but changes with the distance from the borehole. This condition could be taken into consideration, but the solution of the electrical direct problem for such case is very complicated. Any kind of invasion resistivity profile can be approximated by many cylindrical layers of homogeneous resistivities. A recursive formula is derived by which the many‐layer problem can be solved simply. Numerical calculations were made to study the effect of the inhomogeneity of the invaded zone. Apparent resistivities of different Laterolog and normal arrangements were calculated for several models having linearly increasing resistivity profile in the invaded zone. These apparent resistivity values were evaluated by least‐squares fitting to determine the equivalent electrical parameters of the usual model of three homogeneous layers. The results show that there is practically no error in determination of the true resistivity, but the depth of invasion may be significantly smaller than that of the linear resistivity profile.

The many faces of STEM in materials science

1991 ◽  
Vol 49 ◽  
pp. 440-441
Author(s):  
John Silcox
Keyword(s):  
Materials Science ◽  
Auger Spectroscopy ◽  
Dark Field ◽  
High Tc Superconductors ◽  
High Tc ◽  
Acoustic Environment ◽  
Electromagnetic Vibration ◽  
The Many ◽  
Serial Mode

Determination of the microstructure and microchemistry of small features often provides the insight needed for the understanding of processes in real materials. In many cases, it is not adequate to use microscopy alone. Microdiffraction and microspectroscopic information such as EELS, X-ray microprobe analysis and Auger spectroscopy can all contribute vital parts of the picture. For a number of reasons, dedicated STEM offers considerable promise as a quantitative instrument. In this paper, we review progress towards effective quantitative use of STEM with illustrations drawn from studies of high Tc superconductors, compound semiconductors and metallization of H-terminated silicon.Intrinsically, STEM is a quantitative instrument. Images are acquired directly by detectors in serial mode which is particularly convenient for digital image acquisition, control and display. The VG HB501A at Cornell has been installed in a particularly stable electromagnetic, vibration and acoustic environment. Care has been paid to achieving UHV conditions (i.e., 10-10 Torr). Finally, it has been interfaced with a VAX 3200 work station by Kirkland. This permits, for example, the acquisition of bright field (or energy loss) images and dark field images simultaneously as quantitative arrays in perfect registration.

Enhanced information from biological materials through technological improvements in cryo-electron microscopy

1992 ◽  
Vol 50 (1) ◽  
pp. 788-789
Author(s):  
Marc J.C. de Jong ◽  
Wim M. Busing ◽  
Max T. Otten
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
Biological Materials ◽  
Electron Crystallography ◽  
Cryo Electron Microscopy ◽  
Transmission Electron ◽  
The Many ◽  
Technological Improvements ◽  
Beam Damage

Biological materials damage rapidly in the electron beam, limiting the amount of information that can be obtained in the transmission electron microscope. The discovery that observation at cryo temperatures strongly reduces beam damage (in addition to making it unnecessaiy to use chemical fixatives, dehydration agents and stains, which introduce artefacts) has given an important step forward to preserving the ‘live’ situation and makes it possible to study the relation between function, chemical composition and morphology.Among the many cryo-applications, the most challenging is perhaps the determination of the atomic structure. Henderson and co-workers were able to determine the structure of the purple membrane by electron crystallography, providing an understanding of the membrane's working as a proton pump. As far as understood at present, the main stumbling block in achieving high resolution appears to be a random movement of atoms or molecules in the specimen within a fraction of a second after exposure to the electron beam, which destroys the highest-resolution detail sought.

The Collaborative Medical and Behavioral Management of Chronic Cough

2009 ◽  
Vol 19 (2) ◽  
pp. 49-57
Author(s):  
Brian E. Petty ◽  
Seth H. Dailey
Keyword(s):  
Medical Care ◽  
Chronic Cough ◽  
Therapeutic Management ◽  
Ambulatory Setting ◽  
Behavioral Management ◽  
Speech Language Pathologists ◽  
Speech Language Pathologist ◽  
The Many ◽  
Frequent Reason

Abstract Chronic cough is the most frequent reason cited by patients for seeking medical care in an ambulatory setting and may account for 10% to 38% of a pulmonologist's practice. Because chronic cough can be caused by or correlated with a wide array of disorders and behaviors, the diagnosis of etiologic factors and determination of appropriate therapeutic management in these cases can prove to be daunting for the physician and speech-language pathologist alike. This article will describe the phenomenon of chronic cough, discuss the many etiologic factors to consider, and review some of the more common ways in which speech-language pathologists and physicians collaborate to treat this challenging condition.

The departure of the Greeks from Egypt, 1961: the perspective of Greek diplomacy

2020 ◽  
pp. 1-18
Author(s):  
Evanthis Hatzivassiliou
Keyword(s):  
Near East ◽  
Political Leaders ◽  
The Mediterranean ◽  
Younger Generation ◽  
Post War ◽  
The Many ◽  
Economic Failure

The departure of the greater part of the Greek community from Egypt is one of the many sad stories of the post-war Mediterranean. This article focuses upon the reports of the Greek Consul-General in Alexandria, Byron Theodoropoulos, regarding the Egyptian ‘Socialist Laws’ of summer 1961, which gave the coup de grâce to the Greek community. It argues that the expulsion of the Greeks was part of a wider redistribution of power in the region. This episode, together with similar experiences in other parts of the Mediterranean, evidently cemented the determination of a younger generation of political leaders and diplomats to seek Greece's future in the cosmopolitan, post-nationalist West, rather than in a ‘Near East’ rife with nationalism and economic failure.

Investigation of Radiant Superheater Crossover Pipe Weld Cracking at Big Cajun II Station

2002 ◽  
Author(s):  
James P. King ◽  
Robert D. Hendrix
Keyword(s):  
Growth Curves ◽  
Performance Testing ◽  
Circumferential Welds ◽  
Root Cause ◽  
Ultrasonic Time ◽  
History Of ◽  
The Many ◽  
Stress Fatigue ◽  
Ultrasonic Shear

This paper describes the many features of a detailed investigation into the determination of a root cause for internal cracking found in the circumferential welds of radiant superheater crossover piping lines, in the Units No. 1 and 2 boilers at Big Cajun II Station in New Roads, Louisiana. The history of inside diameter, circumferential cracks dates back to 1992. The cracking had been recorded during several outages for both units. It was discovered by use of ultrasonic shear wave testing, and verified by ultrasonic time of flight diffraction methods. During each of the ensuing unit outages, the crack depths were recorded and mapped. Repairs were undertaken by machining out the complete girth weld followed by re-welding. During the interim years cracking did re-occur at many of the weld locations. In 2000, a detailed investigation into the cause of the cracking was initiated, which resulted in recommendations for resolving the ongoing problem. This detailed study included; nondestructive testing and metallurgy of removed metal samples, boiler performance testing and analysis and stress, fatigue and fracture mechanics evaluations. The detailed background, applications and results of the many and varied testing and analytical tasks are fully described herein. The main conclusion to the root cause of the cracking is identified as fatigue caused by the combined effects of thermal and pressure cycles. Recommendations are given which address the actions needed to limit or prevent re-occurrence of the cracking, including revised boiler operating procedures. In addition, a series of fatigue crack growth curves is presented, as a monitoring toot for evaluating existing cracks in the welds.

scholarly journals Routine Determination of Ice Thickness for Cryo-EM Grids

2018 ◽  
Author(s):  
William J. Rice ◽  
Anchi Cheng ◽  
Alex J. Noble ◽  
Edward T. Eng ◽  
Laura Y. Kim ◽  
...  
Keyword(s):  
Data Collection ◽  
Sample Preparation ◽  
Quality Data ◽  
Ice Thickness ◽  
Limiting Factor ◽  
Test Cases ◽  
Slowing Down ◽  
Routine Monitoring ◽  
The Many

AbstractRecent advances in instrumentation and automation have made cryo-EM a popular method for producing near-atomic resolution structures of a variety of proteins and complexes. Sample preparation is still a limiting factor in collecting high quality data. Thickness of the vitreous ice in which the particles are embedded is one of the many variables that need to be optimized for collection of the highest quality data. Here we present two methods, using either an energy filter or scattering outside the objective aperture, to measure ice thickness for potentially every image collected. Unlike geometrical or tomographic methods, these can be implemented directly in the single particle collection workflow without interrupting or significantly slowing down data collection. We describe the methods as implemented into the Leginon/Appion data collection workflow, along with some examples from test cases. Routine monitoring of ice thickness should prove helpful for optimizing sample preparation, data collection, and data processing.

Use of projects methods in study of second context line of computer science

2021 ◽  
Vol 47 (2) ◽  
pp. 217-223
Author(s):  
A. Azizova ◽  
Keyword(s):  
Computer Science ◽  
Cognitive Abilities ◽  
Functional Model ◽  
Science Research ◽  
Educational Process ◽  
Project Method ◽  
Methodological Research ◽  
The Many ◽  
Procedural Components

The relevance of the topic is justified by the many existing interpretations of the cognitive interest of students. The authors note the lack of scientific and methodological research on the problem of the development of the cognitive abilities in the study of computer science and propose to focus on only one aspect of the research. The aim of the study is to develop the content and procedural components of the educational process using the project method to develop the cognitive interest of students in teaching the omputer science. Research objectives: determination of the psychological and pedagogical foundations of the project method for the development of students' cognitive interests in teaching and studying computer science; development of a structural and functional model of the project; development of a methodology for organizing project activities of students in teaching computer science. The article presents the results of the experiment, which testify to the successful use of the project method in teaching informatics.

Determination of Diazepam (Valium) Concentrations in Serum by Gas—Liquid Chromatography

1970 ◽  
Vol 16 (3) ◽  
pp. 177-179 ◽  
Author(s):  
Lowell B Foster ◽  
Christopher S Frings
Keyword(s):  
Liquid Chromatography ◽  
Chromatographic Method ◽  
Gas Liquid Chromatography ◽  
Gas Chromatograph ◽  
Serum Samples ◽  
The Many ◽  
Gas Chromatographic Method

Abstract A simple, rapid, and precise gas chromatographic method for determination of serum diazepam concentrations is described. Two milliliters of serum is extracted with chloroform, and the extract is concentrated and injected into a gas chromatograph. Of the many drugs and serum samples tested, none interferes with the determination of diazepam.

Numerical Determination of the Response of a Linear Vibration System With a Singular Mass Matrix

1972 ◽  
Vol 94 (1) ◽  
pp. 64-69
Author(s):  
K. D. Willmert
Keyword(s):  
Multistep Methods ◽  
Mass Matrix ◽  
Linear Equations ◽  
Coefficient Matrix ◽  
Vibrational System ◽  
Wide Range ◽  
Mass Matrices ◽  
The Stability ◽  
The Many

In numerically determining the response of a linear second-order multidegree-of-freedom vibrational system subjected to a general excitation, the common approach of applying one of the many multistep methods of numerical analysis (e.g., Milne-Simpson, Adams-Bashforth, etc.) leads ultimately to the solution of a system of linear equations. However, when the mass matrix of the original vibrational system is singular, the coefficient matrix of the system of equations also becomes singular and thus the response cannot be determined. Presented is a means of applying these multistep methods to vibrational systems which results in a method that is capable of obtaining the response independent of the singularity of the mass matrix. This technique is particularly useful in optimization where the values of the parameters of the system are unknown in advance, and thus the method of determining the response must be applicable for a wide range of values of the parameters. In the development and investigation of this technique, the causes of the stability problems which develop from the application of multistep methods to systems with nearly singular mass matrices become apparent.

scholarly journals Clusters of Galaxies

1980 ◽  
Vol 5 ◽  
pp. 699-714 ◽  
Author(s):  
Neta A. Bahcall
Keyword(s):  
Large Scale ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Clusters Of Galaxies ◽  
Groups Of Galaxies ◽  
Formation And Evolution ◽  
The Rich ◽  
The Many ◽  
The Universe

AbstractClusters and groups of galaxies contain the majority of galaxies in the universe. The rich clusters, while less numerous than the many poor groups, are the densest and largest systems known, and can be easily recognized and studied even at relatively large distances. Their study is important for understanding the formation and evolution of clusters and galaxies, and for a determination of the large-scale structure in the universe.

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