Mechanical Flaws Research Articles

Uso de preservativos, risco e ocorrência de gravidez não planejada e conhecimento e acesso à contracepção de emergência entre mulheres com HIV/aids

This paper focuses both the risk and the occurrence of non-planned pregnancy, abortions, as well as the awareness about and the use of emergency contraception among HIV/aids-infected women. A quantitative observational approach was used after a domiciliary survey in Santo Andre, São Paulo State, Brazil, where it was found that, after receiving the information about the infection, 62.8% adopted the use of male condom, 77.2% using it exclusively, 13% associated with hormone injections, and 9.8% alternated with either interrupted intercourse, fertility schedule or vaginal shower. Mechanical flaws by the use of the preservative occurred to 38%. Added to flaws associated to the alternation with behavioral methods, they caused together 40% of non-planned pregnancy, which occurred to 24% of the interviewed women, 22% resulting in self-provoked abortions. Emergency contraception was known by 51.4%, although only 2.7% had used it. The conclusion is that mechanical or behavioral flaws related to the use of preservative by HIV/aids-infected women increased their exposure to non-planned gestations and abortions. It is needed to amplify both the options and the supply of contraceptive methods, including emergency contraception, with constant re-orientation on the use of preservative among this public.

Magnetic pipe flaw detector ДМТП

-A ДМТП magnetic flaw detector with transverse magnetization of pipes, which was designed at ZAO Spektr is described in brief. It is to be used for inspecting the state of buried gas-main pipelines, detecting mechanical, erosion, and corrosion flaws in them, and estimating their dimensions and location in the tested section. Performance characteristics of the flaw detector are compared with those of earlier designed flaw detectors with longitudinal magnetization of tested pipes.

Mechanisms of salt scaling

A great deal of information has been collected over the years about the phenomenology of salt scaling of concrete, and no single mechanism has been identified that can account for all of the observations. We review the essential facts that any complete theory of scaling must explain, and suggest two mechanisms that seem to be of primary importance. Experiments indicate that damage is worst when the water on the surface of the concrete contains a small amount of solute, regardless of the type of solute. We argue that the role of solute is to create brine pockets in the ice that act as mechanical flaws; when the weakened ice cracks, the crack runs to the surface of the concrete and does superficial damage. An analysis of the stresses created in this way shows that they are more than sufficient to initiate cracks. A second phenomenon, which is present when chloride salts are used, is expansion resulting from precipitation of Friedel's salt. The crystallization pressure from growth of these crystals causes significant expansion of the paste, and results in high stresses on a local scale near the ice/paste boundary. This can substantially weaken the material and facilitate scaling.

Estimating Noise Level in Dynamical Behavior for Detecting Mechanical Damage

The diagnostic algorithm introduced by Wayland et al. to test for degrees of visible determinism in complex dynamical behavior is applied to precise estimation of noise level for the gear-noise sound emanated from automobile automatic transmissions. It is shown that the method successfully captures such a small difference in acoustical characteristics indicating micro mechanical flaws on the gear surface that power spectral analysis fails to detect.

Effects of mechanical flaws in open-ended coaxial probes for dielectric spectroscopy

A detailed study of dielectric properties of breast tissue in the 0.1 to 20 GHz frequency range currently under way uses open-ended teflon coaxial probes as sensors. This letter quantifies the effects of small mechanical imperfections at the probe aperture on the measured reflection coefficient. The mechanical flaws in the probe can lead to significant errors, thus probes for dielectric spectroscopy of breast tissue have to be carefully manufactured.

Fatigue crack growth in 316 type stainless steel at temperatures and displacement damage rates representative for the first wall loading

Fatigue crack growth initiating from preexisting mechanical flaws is one of the major parameters to be considered when evaluating the endurance life of tokamak reactor components. The anticipated pulsed operation of Next Step systems will impose cyclic thermomechanical loads on structural materials associated with radiation damage which can limit the lifetime of the first wall. Fatigue crack growth under cyclic tensile stress was measured on AISI 316 stainless steel under proton irradiation at a displacement damage rate of ≈10 −7 dpa s −1 and at 373, 473, and 573 K. The influence of proton irradiation appears to be more significant at the primary stage of crack propagation, causing only a slight decrease of the fatigue crack growth rate in the secondary stage. Irradiation tends also to prolong fatigue life. The results suggest that under irradiation at low fluences and low temperatures, the effect is due to hardening by defect agglomerates produced by displacements.

Literature and Medicine

4fc Literature and Medicine Lawrence J. Schneiderman And glutted now with learning's golden gifts, He surfeits upon cursed necromancy. Nothing so sweet as magic is to him, Which he prefers before his chief est bliss. —Christopher Marlowe, The Tragical History of Doctor Faustus The very word startled me when I first heard it in medical school. Literature. The professors were referring to those tedious journal articles they made us scurry after as literature. For one who had sipped sherry in Gothic rooms whilst pondering Homer, Tolstoy, Proust, Joyce, et al., such barbarity was tantamount to child abuse. I am afraid my standards have slipped since those precious days. I use the word myself now when I want to send medical students scurrying, although I like to think I would as happily see them scamper back with the Kansas Quarterly, say, as with the New England Journal of Medicine. Isn't this, after all, how we once regarded the ideal physician— nurtured by both the Humanities and the Sciences? We hardly remember, now that technology and specialization have overwhelmed the humanistic tradition of medicine—and philosophy, music, and history, for that matter. But perhaps we are beginning to experience a kind of microrenaissance . Not only a few perceptive individuals, but national commissions, are urging us to revive the humanities. Once again, it is up-to-date to be old-fashioned. (When I want to tease my "young Turk" colleagues, I accuse them of being back in the Age of Molecular Biology.) As with any renaissance, the process involves rediscovery. We are discovering things we never should have forgotten—that the practice of medicine is not limited to the repair of mechanical flaws. Physicians deal with that larger, more elusive subject, the human condition. By training, if not by instinct, scientists follow Occam's Law, seeking the simplest explanation to a scientific mystery. As anyone who has Literature and Medicine 1 (Rev. ed., 1992) 40^1 © 1992 by The Johns Hopkins University Press Lawrence J. Schneiderman 41 grown up on the great writers will tell you, simple answers to human mysteries are likely to be wrong. It is a commonplace that literature teaches the meaning of life. I believe it does more. Like science, literature is a way of perceiving. Great literature re-creates our world with the intense imagery of metaphor. Literature leaps where the scientific method treads circumspectly. Literature constructs the most profound truths out of selected data and delirious imaginings. I know scientists who are appalled to think that people actually believe that stuff. And yet, great writers do make us believe, using the marvelous powers of language to construct towers and flying machines from which we view earthbound knowledge. They provide unexpected contexts, wild perspectives, allowing us to see better, yet paradoxically to look at such obvious contrasts as health and illness and wonder which is which. Great literature reveals the voluptuousness of disease, the illumination of pain, the generative force of death—the obverse sides of medicine's nemeses. I'm convinced that human beings have a need—perhaps a biologic need—to believe in magic. Even blatant falsehood. At its most grandiose, this leads to religion and tragedy; at its most pathetic, to fad diets and quack cancer cures. But the need is unquenchable; the truths of science will never slake it. It is in this chasm of paradox that some of the greatest literature takes root. And it is here—as well as into the well-lit laboratory —that physicians must peer. ...

Iodine stress corrosion cracking of zircaloy: Laboratory data, a phenomenological model, and predictions of in-reactor behavior

Data from laboratory tests performed on unirradiated and irradiated Zircaloy have been used as the basis for developing a phenomenological model of iodine-induced stress corrosion crack initiation and growth. The model is capable of predicting the response of cladding subjected to complex loading conditions. Major features of the data incorporated into the model include the existence of a threshold stress, the effect of iodine concentration, temperature effects, the role of chemical inhomogeneities and mechanical flaws, crack initiation in smooth specimens, crack propagation rates as a function of stress intensity in flawed specimens, and the detrimental effect of irradiation. The major physical processes addressed by the model include intergranular stress corrosion cracking (SCC), transgranular SCC, ductile rupture, iodine penetration by surface diffusion along existing or incipient cracks, and stress and strain intensification and triaxiality caused by cracks or flaws. A probabilistic description of the size distribution of the flaws found in as-fabricated cladding is used as the basis for quantitatively extrapolating the laboratory test results to predict in-reactor cladding behavior. The in-reactor SCC resistance of a large fuel assembly is predicted to be substantially lower and more variable than that of small laboratory specimens.

Electromagnetic testing for mechanical flaws in steel wire ropes

This paper contains an account of an electromagnetic method of testing for mechanical flaws in wire ropes such as colliery winding ropes, the method comprising the use of a band of in combination with a search-coil system. In the introduction are detailed the advantages of the use of alternating as compared with direct current for the excitation of the magnet system. Section 1 describes the results of an experimental investigation of the penetration of magnetic flux in locked coil wire ropes, for a supply frequency of 50 and 20 cycles per second respectively. In Section 2 the effect of mechanical strain on magnetic permeability is considered, with special reference to a.c. excitation. In Section 3 the change in reluctance of the air space due to eccentricity of the rope in the magnet system is examined. Section 4 contains an account of the construction of the rope-testing magnet system, and the method of utilizing the search band of flux is explained. Section 5 contains the results of tests on a length of wire rope which was specially constructed for the purpose by Messrs. Latch and Batchelor, and in which a series of hidden flaws were incorporated. A complete rope-testing equipment constructed in accordance with the principles explained in this paper has been installed in one of the Carlton Main Co.'s collieries in south Yorkshire.

X. Optical rotatory dispersion. Part III.—The rotatory dispersion of quartz in the infra-red, visible and ultra-violet regions of the spectrum

In an earlier paper on “Optical Rotatory Dispersion” (‘Phil. Trans.,’ 1912, A, vol. 212, pp. 261-297) a description was given of the measurement of the rotatory power of quartz for 24 wave-lengths in the visible region of the spectrum from Li 6708 to Hg 4358. Two important features of this research were:— (1) The discovery, after several years of work on inferior material, of a crystal of quartz of extraordinary optical purity, in which none but mechanical flaws could be detected in a plate 58 mm. in thickness and 150 mm. in diameter. (2) The use of long columns of quartz, made up of cylinders drilled from this crystal, giving even in the visible region rotations of the order of 10,000°, which could be read with an average error amounting only to a few parts per million.