Showing papers on "Literature survey published in 1977"

Development length of prestressing strands

Abstract: Based on an extensive literature survey of bond development, the authors propose a new equation for the transfer length of prestressing strand. This equation accounts for the effects of strand size, initial prestress, and concrete strength at transfer, and is applicable to concrete strengths ranging from 2000 to 8000 psi.

Success in ambylopia therapy as a function of age: a literature survey.

Abstract: It is frequently stated that amblyopia is not correctable after the age of 6 years. Many practitioners report marked success for older patients. To evaluate these conflicting reports, we analyzed the results from 23 published amblyopia studies. Our analysis indicates that substantial numbers of patients over age 6 were successfully treated. Success rates under age 6 were not significantly better than those in older patients when the criterion for success was achievement of 20/30 acuity or better. When a criterion of 4 lines improvement was used, success rates at all ages under 16 were quite similar; in patients 16 and over, success by this criterion was significantly less frequent, but even in this group success was achieved by 42% of the patients.

The history and status of research in fouling of heat exchangers in cooling water service

Abstract: A review of research in fouling by cooling water is presented. The literature survey covers the period from 1924 to the present. Both theoretical and experimental papers are reviewed, and the more important of these studies are categorized in table form. Significant contributions are discussed with respect to theoretical developments and experimental apparatus as well as operating variables such as velocity, temperature, water chemistry, and material effects. An assessment of the current status of cooling water fouling is made, and several areas for future research are suggested. On fait une revue des travaux de recherche sur l'encrassage par l'eau de refroidissement qui ont ete publies depuis 1924; elle embrasse a la fois les articles theoriques et les travaux experimentaux et l'on classifie les plus importants de ceux-ci sous forme de tableaux. On discute les contributions importantes qui ont trait aux progres theoriques, aux appareils experimentaux et aux variables operationnelles telles que vitesse, temperature, chimie de l'eau et effets des materiaux. On evalue la situation actuelle dans le domaine de l'encrassage par l'eau de refroidissement et l'on suggere plusieurs secteurs dans lesquels la recherche pourrait se faire a l'avenir.

Some aspects of the occurrence of boron in alloy steels

Abstract: High-resolution boron autoradiography and a literature survey have enabled an assessment to be made of the location of the small amounts of boron (0.002–0.005%) added to alloy steels. It has been shown that boron readily segregates to fcc carbides to give boro-carbides such as M23(BC)6 and V4(BC)3, and that metal borides are not formed in steels with this level of boron addition. Boron also segregates to austenite grain boundaries on slow cooling low-alloy steels below 980°C. Grain-boundary segregation thus occurs in ½%Mo–B bainitic steels as predicted by some harden ability theories. However, quenched and tempered Cr-Mo-V creep-resisting steels do not have boron at the austenite boundaries and the boron does not segregate to the boundaries even after creep testing for > 16 000 h at 550°C. The observed microstructural effects have been related to mechanical properties and interpreted in terms of vacancy–boron interactions.

Distribution of large basaltic intrusions in the Icelandic crust and the nature of the layer 2–layer 3 boundary

Abstract: Basaltic intrusions more than 20 m thick are relatively rare in Iceland and are mainly associated with central volcanic complexes. A literature survey shows that the majority of large (⩾1 km2 in area) basaltic intrusions are intruded into soft and structureless host rocks such as tuffaceous hyaloclastites, sediments, vent and caldera agglomerates, hydrothermally propylitized lavas, and hot and still partly liquid silicic intrusive material. It appears that, upon entering host rock that breaks irregularly, the upwelling magma may expand within the host rock rather than penetrate upward along a narrow fracture to form a dike. This suggests that magma may tend to spread out laterally within the highly altered base of seismic layer 2 (lava layer) rather than penetrate the progressively harder (less altered) lava pile. The boundary of layers 2 and 3 (intrusive layer) could therefore be controlled by a metamorphic front at which the degree of alteration makes the lava pile lose its coherence and accommodate large intrusions. This model is compatible with the correspondence previously observed in Iceland between depths to seismic layer 3 ( VP = 6.5 km/s) and geothermal gradients as measured in bore holes.

Influence of anesthetics, ethyl alcohol, and Freon on dark adaptation of monkey cone ERG.

Abstract: Cone dark adaptation curves were measured in a rhesus monkey using the electroretinogram (ERG) response to a 40 Hz flickering stimulus. The influence of anesthetics on the time course of dark adaptation was studied. All volatile anesthetics tested (methoxyflurane, halothane, enflurane, ether, chloroform) retarded dark adaptation but to different degrees; urethane, ethyl alcohol, and Freon 11 also retarded dark adaptation. No effect was found for barbiturates and ketamine. It seems unlikely that metabolites play a role in the observed phenomena. A literature survey reveals that several studies on dark adaptation or visual pigment regeneration might have suffered from influences of the anesthetic used. The cause of the phenomenon might lie either in anesthetics-induced membrane changes or in hindrance of the isomeration of 11-trans retinal to 11-cis retinal.

A Review of Spectroscopic Information in the Visible and Ultraviolet Region for Diatomic Molecules of Astrophysical Interest

Abstract: Spectroscopic information in the region approximately between 950 A and 5000 A for 42 diatomic molecules of astrophysical interest is summarized from laboratory data and a general literature survey. Three tables are generated. The first one contains the measured lifetimes from the laboratories, electronic transitions, band and line designations, Franck-Condon factors, calculated line strengths, calculated vibrational and rotational oscillator strengths. The second table has transitions, rotational lines in wavelengths ascending order. The thhd table lists the electronic transitions in spectroscopic notation and references of the second table. These data are useful in selecting transitions in searches for possible molecular species in the interstellar medium. This compilation arose primarily through the expressed needs of the OAO Copernicus satellite program at the Princeton University Observatory.

Behaviour of a sex-differential fertility gene in hermaphrodite populations

Abstract: In genera of flowering plants that contain closely related gynodioecious and near dioecious species, near dioecy has probably evolved from gynodioecy by gradual reduction of seed set on hermaphrodites, caused by the action of several genes for partial female sterility. A literature survey shows that several types of sex-function differential fertility effects are widespread in hermaphrodite plants, so that a model of such variation may be of interest both as a model of normal hermaphrodite populations, and for the above evolutionary process. Such a model is presented where there is a dominant or non-dominant gene p for partial female sterility (ovule fertility values w3, w5 t1. Numerical results are given for equilibrium populations and include some cases of complete female sterility for comparison. These results show that frequencies of subhermaphrodites decrease with increased selfing. The heterozygous subhermaphrodite is the fittest, and the homozygous subhermaphrodite the least fit genotype. The fitness of the heterozygous subhermaphrodite decreases, and that of the hermaphrodite increases, with increased selfing. Except for males, proportions of ovule offspring decrease with increased selfing, and again with this exception and with t1 ≠ 1, t2 is highest for heterozygous subhermaphrodites, and for this type is > t1 whereas t2 is least for hermaphrodites. The total ovule production of the population increases, and total pollen production decreases, with increased selfing.

Literature Survey and Preliminary Evaluation of Streambank Protection Methods

Abstract: : This document contains the results of the literature survey and two preliminary studies of streambank erosion control. Preliminary investigations were conducted to identify the mechanisms that contribute to streambank erosion and to evaluate the effectiveness of the most widely used streambank protection methods. Appendices include: (1) The text of the 'Streambank Erosion Control Evaluation and Demonstration Act of 1974'; (2) A list of commercial concerns that market streambank protection products; (3) A glossary of streambank protection terminology; (4) A detailed bibliography resulting from the literature survey; (5) A listing of selected bibliographies related to streambank protection.

Dinamica del mercado de trabajo urbano: el sector informal urbano en America latina

Abstract: ILO pub-WEP pub-PREALC pub. Working paper on the urban area informal sector in Latin America - presents a literature survey of economic theories concerning the urban labour market in general, and of the functioning, importance and problems (underemployment, low incomes, etc.) of the informal sector. Bibliography pp. 46 to 51.

Immunostimulation or immunodepression

Abstract: Our experimental studies and extensive literature survey established that the overall response of an experimentally modified host defense system is strongly dose-dependent, irrespective of either the modifying agent or the test model system. If a sufficiently broad dose range is used, an irregular, nonlinear, nonmonotonic response curve is formed, generally W- or M-shaped, depending on the parameters selected for the representation, with two peaks of relative maximal effect. Accordingly, a modifying agent may exhibit, in some cases, dual effect--stimulation and depression, each at different dose levels. This typical response is defined as characteristic of the entire host defense system and therefore implies a biologically integrated system. The described dose-response relationship mandates the use of multiple doses in evaluation experiments, to establish efficacy and especially to design optimal dose schedules for experimental and clinical application of any agent modifying the host defense system activity.

Haloethylene-related compounds of industrial, environmental, and medical significance

Abstract: A broad-based literature survey was made for chemicals that contain either a haloethylene or a related substructure. Two hundred and sixty-two compounds, including synthetic intermediates, pesticid...

Electrification by Contact Charge Exchange: A Literature Survey of Microscopic Models

Abstract: There is a wide assortment of complicated electrical charge-exchange phenomena that can occur when two materials are simply brought into contact and then separated. The relevant literature is extensive and complicated. Thus the literature on microscopic models of contact electrification is surveyed, and the essential features are systematically condensed so that comparisons can be readily made between the various theoretical models. Particular attention has been focused on controversies and some areas in need of investigation.

Electric motor reliability model

Abstract: : An existing data failure bank consisting of over 2000 actual fractional horsepower (FHP) motor failures was upgraded and utilized to develop a failure model for FHP motors. Motor failures were dominated by two failure modes; i.e., winding failures and bearing failures. A mathematical reliability model was developed for each failure mode utilizing a Weibull cumulative distribution function and regression technique. Results of a literature survey of both failure modes were used to supplement failure data where required and verify the developed models. Failure modes were recombined into a competing risk cumulative distribution model for use in predicting overall motor life and failure rates.

Uniaxial Extension and Compression in Stress-Strain Relations of Rubber.

Abstract: A comprehensive literature survey shows the general applicability of the generalized normalized Martin, Roth and Stiehler equation to uniaxial stress-strain data in extension and compression on rubber vulcanizates. The equation can be expressed as F/M=(L−1−L−2) expA (L−L−1) where F is the stress on the undeformed section and L the ratio of stressed to unstressed length. The equation contains two constants—M, Young's Modulus, the slope of the stress-strain curve at L=1, and A an empirical constant. The conformity of stress-strain data to the equation can readily be determined by a plot of logF/(L−1−L−2) against (L−L−1). In almost every case a straight line is obtained, from the slope and intercept of which both the constants can be determined. The range of validity of the equation usually begins near L=0.5 (in the compression region) and continuing through the region of low deformations often extends to the region of rupture in extension. If uniaxial compression data are available the modulus can ...

[Rare case of attempted suicide by drilling a joiner's drill into the head].

Abstract: The authors report a rare case of suicidal attempt with drilling of a joiner's drill into the head. The patient was mentally ill. In the light of literature survey the rarity of such self-inflicted injuries is stressed, the operative technique is discussed and the usefulness of angiography in certain cases is pointed out. Language: pl

Clinical psychology in the African context

Abstract: Clinical psychology arrived late on the African continent, and is still fighting for recognition. This state of affairs coupled with shortage of personnel has resulted in paucity of research data and poor quality of research work. The se facts are documented with a brief historical and literature survey. The author observes that most of the available work is descriptive and anecdotal, based, as it were, on intuition rather than systematic observation. Selected works on schizophrenia, depression, anxiety, children's adjustment problems, behaviour modification and influence are discussed in this light. Neither psychiatric nosology and diagnosis nor treatment methods and procedures have been effectively investigated. Problems of faulty design and misleading interpretation of research results abound. The conclusions which have been drawn from most empirical research data are probably not the most appropriate. It is therefore suggested that any worker wishing to rely on such available information may ...

Determination of constant-volume balloon capabilities for aeronautical research

Abstract: The proper application of constant-volume balloons (CVB) for measurement of atmospheric phenomena was determined. And with the proper interpretation of the resulting data. A literature survey covering 176 references is included. the governing equations describing the three-dimensional motion of a CVB immersed in a flow field are developed. The flowfield model is periodic, three-dimensional, and nonhomogeneous, with mean translational motion. The balloon motion and flow field equations are cast into dimensionless form for greater generality, and certain significant dimensionless groups are identified. An alternate treatment of the balloon motion, based on first-order perturbation analysis, is also presented. A description of the digital computer program, BALLOON, used for numerically integrating the governing equations is provided.

Literature survey of emissions associated with emerging energy technologies

Abstract: A literature survey was conducted to address fuel contaminants and atmospheric emissions from the following energy-related operations: coal gasification, coal liquefaction, shale oil production, and petroleum refining. Sulfur and nitrogen found in coal, coal liquid product, shale oil, and petroleum crude are, for the most part, organically bound. Only coal was found to have substantial amounts of inorganic contaminants, and this was as pyrite (FeS2). The sulfur content of most fuels is less than 5% and occurs as thiols (mercaptans), sulfides, disulfides, and thiophenes. Nitrogen is usually reported at less than 2% and occurs as pyridines, pyrroles, indoles, carbazoles, and benzamides. Quantitative estimates of criteria air pollutant emissions from energy-related operations are tabulated. A broad spectrum of sulfur-containing compounds, nitrogen-containing compounds, and hydrocarbons has been identified from analyses of intermediate process streams and final products from fuel conversion processes. The surveyed literature provides a basis for identifying the major emissions. The same or similar species are expected to be emitted from each fuel conversion facility.

The critical constants of the elements and of some refractory materials with high critical temperatures. a review.

Abstract: A literature survey of critical-point data is presented which covers both the experimental and theoretical work in this field. The static and dynamic, conventional and advanced experimental techniques together with empirical and theoretical approaches are briefly discussed. Theoretical estimates and experimental data on the critical points of the elements are tabulated and the authors and their methods of evaluation are listed. The elements are arranged in the standard order of the Periodic Table. A second table, which deals with nuclear fuel materials, underlines the urgent need for equation-of-state data for reactor safety analysis, and the necessity to develop new techniques in order to extend measurements beyond the range of conventional techniques.

Literature review of nitrogen oxide absorption into water and dilute nitric acid

Abstract: The removal of gaseous nitrogen oxides from off-gas streams is important when reprocessing spent nuclear fuels. The absorption of nitrogen oxides has been the subject of several laboratory and engineering-scale experiments and the theory of nitrogen oxide absorption seems to be well established. However, previous engineering-scale experimental work is not directly applicable to proposed nitrogen oxide removal processes. A literature survey has been conducted to determine the ''state of the art'' in nitrogen oxide absorption. The purpose of this report is to give the results of that survey and make some general observations on nitrogen oxide absorption.

Direct contact condensers: a literature survey

Abstract: A review is given of the literature pertinent to the design of direct contact condensers using water to condense an organic fluid. Both overall performance and fundamental concepts are examined. Recommendations are made regarding the work required to evaluate this concept for use in binary cycles for geothermal power plants.