scholarly journals XIX. Magnetic qualities of iron

1893 ◽  
Vol 184 ◽  
pp. 985-1039 ◽  
Keyword(s):  
Magnetic Hysteresis ◽  
Detailed Examination ◽  
Cyclic Process ◽  
Magnetic Cycle ◽  
Ballistic Method ◽  
Sheet Iron ◽  
Electrical Engineers ◽  
Magnetizing Force ◽  
Cyclic Variations ◽  
Energy Dissipated

Recent applications of electricity, and especially the extended use of transformers, have added particular interest to the study of cyclic magnetizing processes in iron. It has become a matter of consequence to investigate, in various specimens of metal, not only the amount of the energy dissipated by hysteresis in a magnetic cycle, hut the relative amounts under various degrees of magnetization and various intensities of magnetizing force. Other questions arise with regard to the dependence of this loss on the frequency of the cyclic process and on the manner in which it is performed. The experiments to be described in this paper deal mainly with the effects of cyclic variations of magnetizing force. They are intended to contribute some additions to existing data, to answer one or two specific questions, and to exemplify certain more or less novel methods of experimental inquiry. A section at the end of the paper relates to the molecular theory of magnetization, and its adequacy to explain some characteristic manifestations of magnetic hysteresis. Experiments on Rings, by the Ballistic Method. In a paper published eight years ago by one of us, experiments were described in which a piece of soft iron was carried through a numerous series of cycles of magneti­sation, of graded amplitude, with the object of determining the form taken by the curve of magnetization and magnetizing force during the process of reversal between any assigned limits, and of comparing the work spent in the process with the ampli­tude of the magnetization. A similar experiment was described for steel. Since then the importance of such information has been recognized by electrical engineers, and some experiments with a similar object have been made by Messrs, Evershed and Vignoles, and by Mr. C. P. Steinmetz. Notwithstanding, however, the increased interest which now attaches to the matter in consequence of its practical bearing, the available data are still meagre. By way of adding to them, we have made a detailed examination of some ten samples of wire and sheet iron, arranged in the form of rings to be operated on by the ballistic, method.

scholarly journals II. The measurement of magnetic hysteresis

1902 ◽  
Vol 198 (300-311) ◽  
pp. 33-104 ◽  
Keyword(s):  
Magnetic Field ◽  
Magnetic Force ◽  
Permanent Magnets ◽  
Magnetic Hysteresis ◽  
Physical Processes ◽  
Mathematical Expressions ◽  
Sheet Iron ◽  
Standard Specimens ◽  
Simple Instrument ◽  
Energy Dissipated

1. Two ideal physical processes have been devised as the foundations of two methods of deducing mathematical expressions for the energy dissipated in magnetic material through magnetic hysteresis; these processes are due to Professor E. Warburg and to the late Dr. J. Hopkinson. In Warburg’s theory the specimen, in the form of a slender wire, is placed in a magnetic field due to a pair of permanent magnets so arranged as to produce magnetic force parallel to the length of the specimen. The mechanical work spent in moving these magnets through such a cycle of changes of position, that the iron is subjected to a cycle of magnetic changes, is clearly equal to the energy dissipated on account of magnetic hysteresis in the specimen. In terms of the magnetic quantities the energy dissipated per cub. centim. per cycle is — ∫I d H or ∫H d I ergs, where H is the magnetic force and I the intensity of magnetisation. Professor J. A. Ewing has applied the principle involved in Warburg’s theory to the design of a simple instrument by which the hysteresis of any specimen of sheet iron (for the range of induction B = 4000 to B = - 4000 C. G. S. units approximately) is determined by comparison with two standard specimens supplied with the instrument, and previously tested for hysteresis by the ballistic method. The principle has also been employed by W. S. Franklin, by H. S. Webb, and by G. L. W. Gill to obtain absolute determinations of hysteresis.

II. Magnetic qualities of iron

1894 ◽  
Vol 54 (326-330) ◽  
pp. 75-77 ◽  
Keyword(s):  
Magnetic Induction ◽  
Magnetic Force ◽  
Magnetic Hysteresis ◽  
Iron Wire ◽  
Sheet Iron

The paper describes a series of observations of magnetic quality in vai'ious specimens of sheet iron and iron wire. A principal object was to determine the amount of energy lost in consequence of magnetic hysteresis when the iron under examination was carried through cyclic magnetising processes between assigned limits of the magnetic induction B. For this purpose observations of the relation of the induction B to the magnetic force H were made, from which curves were drawn, and the area enclosed by the curves in cyclic magnetising processes was measured.

scholarly journals Social Electrical Engineering: A Pathway for Better Undergraduate Education

2018 ◽  
Vol 5 (1) ◽  
pp. 13
Author(s):  
Amilton Costa Lamas ◽  
Anderson Gomes Domingues
Keyword(s):  
Engineering Students ◽  
Low Cost ◽  
Electrical Engineering ◽  
Cyclic Process ◽  
Communication Analysis ◽  
Professional Recognition ◽  
Electrical Engineers ◽  
White Cane ◽  
Social Capitals ◽  
High Level

As engineering skills becomes a commodity, electrical engineers’ programs are urged to adapt their pedagogical strategies do better prepared their graduates. The 21st century engineers are expected to have a strong technical background while being capable to work with people with different kinds of intellectual and social capitals, and to have a high level of cognitive flexibility. This article reports on the application of an information appropriation method, adopted by the Department of Electrical Engineering at PUC-Campinas, where activities on extension projects are simultaneously conducted along with the regularly schedule classes. The study case is related to the coplanning and cocreation of a technological white cane (proof of connect) between electrical engineering students, social technicians and the visually impaired. In the present case, the technicians were led to reinterpret, adapt and reinvent technology while contributing to the design and build of a low cost adaptive electronic sensing aid attachable to a white cane. The collaborative method, applied during conversation rounds, is based on a virtuous cyclic process which includes steps like information capture, validation, guidance and feedback. The engineering students, on the other hand, have the opportunity to develop their communication, analysis and interpretation skills in a way not available in the classroom. They also experience solving conflict situations and find creative uses and applications for they knowledge not otherwise foreseen. The participating students transformed information into knowledge through a dialogical experience with people having a contrasting technological background to its own. Through this experience the engineering graduates emerged with a greater sense of responsibility with the society and a better understanding of what means to be an engineer. Participation in the Extension Project also brought up several opportunities of professional recognition by the technicians and the visual impaired themselves, which stimulated the students do achieve better performance in the course.

scholarly journals On the Nature of the 41-Day Cycle of RR Lyrae

1973 ◽  
Vol 21 ◽  
pp. 31-34
Author(s):  
L. Detre ◽  
B. Szeidl
Keyword(s):  
Phase Shift ◽  
Magnetic Fields ◽  
Light Curve ◽  
Rotation Period ◽  
Magnetic Cycle ◽  
Rr Lyrae ◽  
Tentative Model ◽  
Large Phase ◽  
Cyclic Variations ◽  
Photoelectric Observations

AbstractPhotoelectric observations obtained with the 24-in. telescope of the Konkoly Observatory from 1950 to 1972 show that the amplitudes of the changes of the 0.d57 light-curve in the course of the 41-day cycle undergo considerable cyclic variations. The length of the cycles varies between 3.8 and 4.8 yr. A new cycle always begins with a large phase-shift in the 41-day period; afterwards there is generally no further shift during one 4-yr cycle. Following Julia Balázs’ hypothesis, a tentative model is suggested: The 41-day cycle is the rotation period of the star. Magnetic fields concentrated in a limited longitude zone influence the 0.d57 pulsation in such a way that variations in light amplitude and phase arise as aspect effects of the 41-day rotation period. In this way, the 4-yr cycle can be interpreted as the magnetic cycle of the star. The location of the magnetic fields strongly differs in longitude from cycle to cycle causing the observed large phase shifts at the beginning of a new 4-yr cycle.

Spectroscopic and photometric studies of four W UMa-type eclipsing binaries – II

2019 ◽  
Vol 491 (4) ◽  
pp. 6065-6076 ◽  
Author(s):  
Liyun Zhang ◽  
ZhongZhong Zhu ◽  
Qiang Yue ◽  
Rachel Terheide ◽  
Xianming L Han ◽  
...  
Keyword(s):  
Activity Cycle ◽  
Spectroscopic Studies ◽  
Magnetic Activity ◽  
Time Effect ◽  
Eclipsing Binaries ◽  
Light Curves ◽  
Cyclic Variation ◽  
Magnetic Cycle ◽  
Orbital Parameters ◽  
Cyclic Variations

ABSTRACT We performed photometric and spectroscopic studies on four W Ursae Majoris eclipsing binaries (V384 Ser, AQ Psc, V480 Gem and 2MASS J07095549+3643564). The binaries were observed from 2015 to 2018. The orbital period of V384 Ser showed an interesting cyclic variation overlaying a decreasing period, which may be caused by the light-time effect (LITE) of approximately 2.84 ± 0.01 yr or the magnetic activity cycle of 2.83 ± 0.01 yr. For AQ Psc, we found cyclic variations in its period caused by the LITE either as a result of a tertiary companion or because of a magnetic activity cycle. We derived the cycle of the tertiary component of AQ Psc as 23.87 (±0.14) yr or a magnetic cycle of 44.08 (±1.15) yr. We revised the linear ephemeris of eclipsing binaries V480 Gem and 2MASS J07095549+3643564. We also determined their orbital parameters and star-spot parameters by fitting the light curves. In addition, we found weak excess emissions in the LAMOST spectra of V384 Ser, AQ Psc, V480 Gem and 2MASS J07095549+3643564 in the Hα line, which indicates weak chromospheric activities.

Long-term Cyclic Variations of Prominences, Green and Red Coronae over Solar Cycles

2000 ◽  
Vol 179 ◽  
pp. 201-204
Author(s):  
Vojtech Rušin ◽  
Milan Minarovjech ◽  
Milan Rybanský
Keyword(s):  
Emission Lines ◽  
High Latitudes ◽  
Green Line ◽  
Solar Cycles ◽  
The South ◽  
Coronal Emission ◽  
Local Maxima ◽  
The North ◽  
Cyclic Variations

AbstractLong-term cyclic variations in the distribution of prominences and intensities of green (530.3 nm) and red (637.4 nm) coronal emission lines over solar cycles 18–23 are presented. Polar prominence branches will reach the poles at different epochs in cycle 23: the north branch at the beginning in 2002 and the south branch a year later (2003), respectively. The local maxima of intensities in the green line show both poleward- and equatorward-migrating branches. The poleward branches will reach the poles around cycle maxima like prominences, while the equatorward branches show a duration of 18 years and will end in cycle minima (2007). The red corona shows mostly equatorward branches. The possibility that these branches begin to develop at high latitudes in the preceding cycles cannot be excluded.

Electron Irradiation Effects in Polyoxymethylene Crystals Grown Inside Trioxane Crystals

1971 ◽  
Vol 29 ◽  
pp. 78-79
Author(s):  
J. P. Colson ◽  
D. H. Reneker
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Detailed Examination ◽  
The Other ◽  
Electron Micrograph ◽  
Irradiation Effects ◽  
Threefold Axis ◽  
Typical Sample ◽  
Polymer Crystals ◽  
Chain Axis

Polyoxymethylene (POM) crystals grow inside trioxane crystals which have been irradiated and heated to a temperature slightly below their melting point. Figure 1 shows a low magnification electron micrograph of a group of such POM crystals. Detailed examination at higher magnification showed that three distinct types of POM crystals grew in a typical sample. The three types of POM crystals were distinguished by the direction that the polymer chain axis in each crystal made with respect to the threefold axis of the trioxane crystal. These polyoxymethylene crystals were described previously.At low magnifications the three types of polymer crystals appeared as slender rods. One type had a hexagonal cross section and the other two types had rectangular cross sections, that is, they were ribbonlike.

A new dissociation mode for dislocations in silicon

1978 ◽  
Vol 36 (1) ◽  
pp. 346-347
Author(s):  
A. Ourmazd ◽  
G.R. Booker ◽  
C.J. Humphreys
Keyword(s):  
Detailed Examination ◽  
Experimental Results ◽  
Dislocation Network ◽  
Weak Beam ◽  
Phosphorus Doped

A (111) phosphorus-doped Si specimen, thinned to give a TEM foil of thickness ∼ 150nm, contained a dislocation network lying on the (111) plane. The dislocation lines were along the three <211> directions and their total Burgers vectors,ḇt, were of the type , each dislocation being of edge character. TEM examination under proper weak-beam conditions seemed initially to show the standard contrast behaviour for such dislocations, indicating some dislocation segments were undissociated (contrast A), while other segments were dissociated to give two Shockley partials separated by approximately 6nm (contrast B) . A more detailed examination, however, revealed that some segments exhibited a third and anomalous contrast behaviour (contrast C), interpreted here as being due to a new dissociation not previously reported. Experimental results obtained for a dislocation along [211] with for the six <220> type reflections using (g,5g) weak-beam conditions are summarised in the table below, together with the relevant values.

High-resolution scanning electron microscopy of thin-film magnetic media of magnetic recording disk

1992 ◽  
Vol 50 (2) ◽  
pp. 1334-1335
Author(s):  
K. Ogura ◽  
H. Nishioka ◽  
N. Ikeo ◽  
T. Kanazawa ◽  
J. Teshima
Keyword(s):  
Thin Film ◽  
Fine Structure ◽  
High Resolution ◽  
Magnetic Recording ◽  
High Performance ◽  
Magnetic Hysteresis ◽  
Grain Structure ◽  
Magnetic Media ◽  
Cross Sectional ◽  
Resolution Observation

Structural appraisal of thin film magnetic media is very important because their magnetic characters such as magnetic hysteresis and recording behaviors are drastically altered by the grain structure of the film. However, in general, the surface of thin film magnetic media of magnetic recording disk which is process completed is protected by several-nm thick sputtered carbon. Therefore, high-resolution observation of a cross-sectional plane of a disk is strongly required to see the fine structure of the thin film magnetic media. Additionally, observation of the top protection film is also very important in this field.Recently, several different process-completed magnetic disks were examined with a UHR-SEM, the JEOL JSM 890, which consisted of a field emission gun and a high-performance immerse lens. The disks were cut into approximately 10-mm squares, the bottom of these pieces were carved into more than half of the total thickness of the disks, and they were bent. There were many cracks on the bent disks. When these disks were observed with the UHR-SEM, it was very difficult to observe the fine structure of thin film magnetic media which appeared on the cracks, because of a very heavy contamination on the observing area.

Communication Sciences and Disorders PhD Graduates' Perceptions of Their PhD Program

2020 ◽  
Vol 5 (2) ◽  
pp. 463-478
Author(s):  
Elizabeth Crais ◽  
Melody Harrison Savage
Keyword(s):  
Detailed Examination ◽  
Career Expectations ◽  
Doctoral Preparation ◽  
Creative Solutions ◽  
Phd Education ◽  
Doctor Of Philosophy ◽  
First Time ◽  
Students Success ◽  
Phd Program

Purpose The shortage of doctor of philosophy (PhD)–level applicants to fill academic and research positions in communication sciences and disorders (CSD) programs calls for a detailed examination of current CSD PhD educational practices and the generation of creative solutions. The intended purposes of the article are to encourage CSD faculty to examine their own PhD program practices and consider the perspectives of recent CSD PhD graduates in determining the need for possible modifications. Method The article describes the results of a survey of 240 CSD PhD graduates and their perceptions of the challenges and facilitators to completing a PhD degree; the quality of their preparation in research, teaching, and job readiness; and ways to improve PhD education. Results Two primary themes emerged from the data highlighting the need for “matchmaking.” The first time point of needed matchmaking is prior to entry among students, mentors, and expectations as well as between aspects of the program that can lead to students' success and graduation. The second important matchmaking need is between the actual PhD preparation and the realities of the graduates' career expectations, and those placed on graduates by their employers. Conclusions Within both themes, graduate's perspectives and suggestions to help guide future doctoral preparation are highlighted. The graduates' recommendations could be used by CSD PhD program faculty to enhance the quality of their program and the likelihood of student success and completion. Supplemental Material https://doi.org/10.23641/asha.11991480

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