Johnson's Theory Research Articles

An Elastic-Plastic Finite Element Model of Rolling Contact, Part 1: Analysis of Single Contacts

This paper describes a two-dimensional (plane strain) elastic-plastic finite element model of rolling contact that embodies the elastic-perfectly plastic, cycle and amplitude-independent material of the Merwin and Johnson theory, but is rigorous with respect to equilibrium and continuity requirements. The rolling contact is simulated by translating a semielliptical pressure distribution. Both Hertzian and modified Hertzian pressure distributions are used to estimate the effect of plasticity on contact width and the continuity of the indentor-indentation interface. The model is tested for its ability to reproduce various features of the elastic-plastic indentation problem and the stress and strain states of single rolling contacts. This paper compares the results derived from the finite element analysis of a single, frictionless rolling contact at p0/k = 5 with those obtained from the Merwin and Johnson analysis. The finite element calculations validate basic assumptions made by Merwin and Johnson and are consistent with the development of “forward” flow. However, the comparison also reveals significant differences in the distribution of residual stress and strain components after a single contact cycle.

A Study on the Mean Crushing Load of Circular Cylindrical Shells

The mean crushing load for axially compressed circular cylindrical shells is studied in the present paper. The theoretical rigid-plastic solutions for the axisymmetric and the nonaxisymmetric collapse mode are compared with the experimental data given in the published literatures and their validities are investigated. The obtained results are summarized as follows : (1) For the mean crushing load in case of axisymmeric collapse the modified Alexander's solution (eq. (10)) in which the effect of stroke to length ratio is taken into account is extremely in good agreement with the experimental results with regard to the crushing wavelength as well as the crushing load.(2) In the range of large R/t ratios where the crushing mode is mainly due to the non-axisymmetric elastic buckling the modified Johnson's theory (eq. (33)) in which the inextensional collpse mode is assumed gives reasonable mean crushing stresses.(3) In the range of small R/t ratios where the crushing mode is mainly due to the nonaxisymmetric plastic buckling the generalized Pugsley's theory (eq. (29)) in which the internal plastic work by the membrane shearing force as well as the bending moment is taken into account agrees relatively well with the experimental results.(4) When the axisymmetric and the non-axisymmetric collapse are both considered, the modified Alexander's theory and the modified Johnson's theory can be regarded as the upper and the lower bound solution for mean crushing stresses respectively, however, no rigidplastic solution is sufficiently accurate for non-axisymmetric collapse mode. The detailed numerical analysis such as the finite element analysis will be needed in order to estimate the mean crushing load for the non-axisymmetric collapse mode with sufficient accuracy.

Development of a Decision-Making Inventory to Assess Johnson's Decision-Making Styles

Johnson's decision-making theory suggests that information can be gathered in a systematic or spontaneous manner and that this information is analyzed either externally or internally. This article ...

A survey of communicative disorders students' attitudes toward stuttering

Cooper's (1975) Clinician Attitudes Toward Stuttering (CATS) inventories were conpleted by 1,902 speech-language pathology and audiology students from 33 universities, each in a different state. The majority of respondents perceived stutterers as having psychosocial problems and believed that client and parental counseling were essential aspects of treatment. These views were relatively unaffected by student training and clinical exposure. In addition, most of the assumptions of Johnson's diagnosogenic theory of stuttering were held by the majority of the students surveyed. Most of the respondents believed that stuttering was difficult to modify and that speech clinicians were neither adept nor comfortable treating stutterers. These latter attitudes were significantly affected by training, i.e., the more advanced the students' training, the more pessimistic their views on clinician competence. Other professional attitudes and the effect of training on them are also discussed.

Rubber friction and the rheology of viscoelastic contact

The phenomena accompanying friction at low speeds (1–1500 μm/s) of a clean glass hemisphere ( R = 2 mm) on a plate of soft, transparent, natural vulcanized rubber ( E' = 1.6 × 10 7 dynes/ cm 2) were studied using an optical microscope equipped with Nomarski interference contrast (× 150) and with a device to form Newton's rings around the area of contact. The friction force under loads of zero, 1 and 2 × 10 3 dynes was recorded, and its variation on the appearance of Schallamach waves was assessed. The elastic adhesion between both surfaces was specially studied, and Johnson's theory verified. The profile of the deformed rubber surface was determined, in static as well as in dynamic conditions, and the geometric process of the formation of detachment waves was demonstrated. The contact angle between rubber and glass was measured in the case of zero load. Relaxation phenomena were observed for the free surface and the bound surface (interfacial relaxation), and the corresponding characteristic relaxation times roughly estimated. Some conditions for the appearance of Schallamach waves were established and hypotheses made concerning their eventual role in the problems of tyre and seal friction. The need for a new theoretical approach to these questions is briefly discussed.

James Weldon Johnson's Theories and Performance Practices of Afro-American Folksong

James Weldon Johnson's Theories and Performance Practices of Afro-American Folksong

Effects of type of listeners and listening instructions on the attention to manner and content of a severe stutterer's speech

Naive listeners and speech therapists reacted to the content and manner of a severe stutterer's speech on the basis of various prelistening instructions. Results indicated that the degree of the listeners' pre-experimental sophistication and the severity of stuttering were more important in determining listeners' attention than most of the pre-listening instructions. Attention of both types of listeners was paid mainly to the manner of speaking. It is suggested that Johnson's Diagnosogenic theory is not applicable to the interaction between severe stutterers and their listening environment. It is also suggested that therapy should be aimed at a reduction of nonfluencies before an attempt is made to change the listening environment.

Dr. Johnson, Mandeville, and "Publick Benefits"

T HE BELIEF that Dr. Johnson's theories were largely borrowed from Mandeville has been expressed by F. B. Kaye, as well as by G. Birkbeck Hill and others following them.' Since this belief does not seem to accord wholly with Johnson's conversations and seems to contradict the tenor of his writings, it is the purpose of the following discussion to re-evaluate his pronouncements on in the Life and in his poetic and prose writings. Although the eighteenth century saw the birth of modern economic theory, it is necessary to remember that the popular terms in which such problems were discussed were different from our own: even the term economics did not achieve currency until after the first third of the next century.2 The usual approach was more political-even literary-and moral in emphasis, and devolved typically upon the Mandevillean distrust of charity and the dispute over the good or evil of luxury or of, as Veblen put it, conspicuous consumption. The traditional view of luxury was derived from the orthodox medieval contempt for the vain and transitory treasures of this life, a theological condemnation also readily seen in Spenser's dramatizing of the deadliest of the seven deadly sins in the rotten luxury of Lucifera's palace. The two schools of thought that most seriously challenged this orthodoxy in the eighteenth century were the deistic, benevolent school of Shaftesbury and the freethinking, egoistical thought of Mandeville.' Johnson could not wholly accept Shaftesbury's benevo-

Changes in the High-Latitude East-West Asymmetry of Cosmic Rays

A large long-term decrease in the east-west asymmetry has been observed at Hobart ($\ensuremath{\lambda}=52\ifmmode^\circ\else\textdegree\fi{}$S; near sea level). This is apparently related to the level of solar activity. In 1950 the asymmetry amounted to $\ensuremath{\alpha}=0.0246\ifmmode\pm\else\textpm\fi{}0.0022$, while in 1954 (a year of sunspot minimum) it was only 0.0108\ifmmode\pm\else\textpm\fi{}0.0016. It is shown that the decrease cannot be explained by changes in the parameters involved in the Johnson theory of the high-latitude east-west asymmetry, leading to the conclusion that the primary particles capable of producing a sea-level penetrating component at these latitudes are not completely isotropically distributed when they reach the upper atmosphere. The asymmetry is to be regarded as a very sensitive indicator of such anisotropy.

The High Latitude East-West -Asymmetry of Cosmic Rays

Measurements of the east-west asymmetry of cosmic rays at sea-level have been made at Hobart and Macquarie Island in geomagnetic latitudes 51.7 and 60.7 �S. respectively. The values obtained have been found to agree satisfactorily with values calculated using a revised form of Johnson's theory.

On the origin of the Carolina Bays

A critical reconsideration of all important theories concerning the origin of the Carolina Bays led to a modified meteorite theory of origin, and to the conclusions: (1) Johnson's theory of “complex origin” is quite untenable; (2) a modified meteorite theory of origin can meet all of Johnson's 29 requirements; (3) such a meteorite theory of origin has not yet been shown to be untenable; and (4) the modified meteorite theory of origin is the least unsatisfactory of all the theories which have been published thus far.

The Carolina "Bays"

Since the area of the bays is almost the entire area of the coastal plain in the two Carolinas, Johnson's complex theory of origin of the Carolina "bays" would violate the laws of conservation of energy, inasmuch as the area of assumed outflow of ground water would have to be the same as the area of intake. Johnson assumed implicitly that the coastal-plain bedrock (chiefly Cretaceous) dips down the slope of the coastal plain toward the southeast in the manner of a textbook illustration of coastal plains, whereas the dip is actually toward the south or slightly southwestward. Therefore, his assumed "spring vents" should have moved northward under his theory, instead of northwestward, as the shape of the bays would require. Other errors of fact and examples of illogical theory in Johnson's spring-vent hypothesis are pointed out. Through a revision of the meteoritic theory it is shown that the supposed impact could have occurred at any one of several times in the geologic past.

Is the Atlantic Coast Sinking? The Evidence from the Tide

ABOUT thirty years ago late Douglas Johnson discussed in this /A journal question of of Atlantic coast under 1 L. title Is Atlantic Coast Sinking?' After referring to then generally accepted view that Atlantic coast of North America was subsiding at rate of one to two feet in a century, he reviewed some recent contributions on problem that controverted this view. For a number of years Johnson had been arguing in his characteristically lucid manner that the so-called proofs of land sinking within historic times were open to alternative explanations, whereas physiographic evidence could only be explained by postulating long-continued coastal stability. Johnson concluded his discussion by quoting from a report on Precise Leveling in New York by Frederick W. Koop, published in I9I5, as follows: From determinations above noted, which are result of spirit leveling of unquestioned accuracy, it is clear that from standpoint of geodesist or engineer there is no reliable evidence to show a general progressive subsidence of Atlantic coast in New York City and vicinity. On contrary, all evidence is in favor of ...... The work of writer [Koop] on Board of Estimate leveling must be construed as a striking confirmation of Professor Johnson's theory of coastal as set forth in preceding paragraphs. It is of especial interest because it is a proof based on engineering methods of during last quarter of a century of very part of coast which is generally supposed to be undergoing most rapid subsidence at present time. It must be noted that question of coastal was only incidental to primary purpose of Precise Leveling in New York City, and technical results embodied in that report are in no manner dependent on that question. In light of present tidal knowledge, a careful reading of that portion ofKoop's report which deals with question of coastal compels one to characterize absolute stability as too strong. Koop based his conclusion on tidal data that are now known to have been insufficient to permit so unequivocal a statement. Since that time, however, a very