Showing papers on "Literature survey published in 1987"

Evolution and Escalation: An Ecological History of Life

Abstract: Here is one biologist's interpretation of the chronology of life during the last six hundred million years of earth history: an extended essay that draws on the author's own data and a wide-ranging literature survey to discuss the nature and dynamics of evolutionary change in organisms and their biological surroundings. Geerat Vermeij demonstrates that escalation--the process by which species adapt to, or are limited by, their enemies as the latter increase in ability to acquire and retain resources--has been a dominant theme in the history of life despite frequent episodes of extinction.

Wettability literature survey - Part 5: The effects of wettability on relative permeability

Abstract: The wettability of a core will strongly affect its waterflood behavior and relative permeability. Wettability affects relative permeability because it is a major factor in the control of the location, flow, and distribution of fluids in a porous medium. In uniformly or fractionally wetted porous media, the water relative permeability increases and the oil relative permeability decreases as the system becomes more oil-wet. In a mixed-wettability system, the continuous oil-wet paths in the larger pores alter the relative permeability curves and allow the system to be waterflooded to a very low residual oil saturation (ROS) after the injection of many PV's of water. The most accurate relative permeability measurements are made on native-state core, where the reservoir wettability is perserved. Serious errors can result when measurements are made on cores with altered wettability, such as cleaned core or core contaminated with drilling-mud surfactants.

Wettability literature survey - Part 4: Effects of wettability on capillary pressure

Abstract: The capillary-pressure/saturation relationship depends on the interaction of wettability, pore structure, initial saturation, and saturation history. No simple relationship exists that relates the capillary pressures determined at two different wettabilities. Therefore, the most accurate measurements are made with cores that have native reservoir wettability. The article describes pore geometry and the pore medium and concludes that because of wettability, pore structure, initial saturation, and inhibition behavior interactions, there is a large range of contact angles where neither oil nor water will imbibe freely into a uniformly wetted reservoir core. In contrast it is sometimes possible for both fluids to imbibe freely into a core with fractional or mixed wettability.

Wettability Literature Survey-Part 6: The Effects of Wettability on Waterflooding

Abstract: Cet article est le sixieme d'une serie consacree a l'influence de la mouillabilite sur l'analyse des carottes. L'auteur etudie l'effet de la mouillabilite sur l'injection d'eau et notamment le coefficient de viscosite de l'huile, sa percee, sa saturation residuelle dans les systemes uniformement ou non mouilles

Phase diagrams and thermodynamic properties of the 70 binary alkali halide systems having common ions

Abstract: A very extensive literature survey of all available phase diagram and thermodynamic data has been carried out for all 40 possible common‐anion binary systems (AX‐BX) and all 30 possible common‐cation binary systems (AX‐AY) involving the alkali halides (A,B =Li,Na,K,Rb,Cs; X,Y=F,Cl,Br,I). A critical analysis and evaluation of these data have been performed with a view to obtaining a ‘‘best’’ evaluated phase diagram and a set of ‘‘best’’ evaluated thermodynamic parameters for each system. To this end, a computer‐assisted coupled analysis of the phase diagram data and the thermodynamic data for each system has been employed. Mathematical expressions for the thermodynamic properties of all known phases have been obtained which are consistent with the measured thermodynamic properties and phase diagrams as well as with established thermodynamic principles and theories of solution behavior. The parameters of these expressions are reported here and have been used to generate the computer‐calculated diagrams in the compilation.

Microeconomic Estimates of Housing Depreciation

Abstract: Measuring economic depreciation in residential real estate is important for deepening our understanding of housing market behavior and for assessing a variety of public policies. Independent estimates of depreciation rates for many metropolitan areas provide a rich data base for analyzing the interaction between structure depreciation and, for example, suburbanization. Also, public policies such as rent control and tax incentives for construction could be better evaluated and designed with improved estimates of depreciation. For example, in an attempt to stimulate construction in 1981 Congress cut allowable depreciation for tax purposes from something like 30 years to 15 years. Then in 1986 in response to apparent over-building, Congress raised the depreciation rate back to 27.5 years. Better estimates of depreciation rates could have contributed to better targeting of incentives. A literature survey indicates significant variation in estimates of depreciation rates for residential real estate. The variation in reported results seems to be due to differences in the definition of depreciation employed, in the models and data used to estimate depreciation rates and, in some cases, the condition of the real estate market examined at the time of the study. A primary objective of this paper is to establish that rates of economic depreciation vary spatially. By using the same hedonic model and representative data from each of 59 metropolitan areas, we are able to eliminate differences in models and data as the only source of variation in estimated depreciation rates and attribute some of the observed variation to differences in housing markets. This paper reports estimates of metropolitan area specific rates of economic depreciation for residential real estate obtained using the hedonic pricing methodology. Separate h donic equations were estimated for owneroc upied and renter-occupied properties for each of 59 metropolitan areas. With the exception of variables that identified particular locations within the urban area, the same hedonic equation was used to estimate tenure spec f c depreciation rates. That is, the same hedonic specification was used for each of the 59 metropolitan areas to estimate depreciation rates for owner-occupied and for renteroccupied housing. We define economic depreciation "to be the decline in asset price (or shadow price) due to aging" (Hulten and Wykoff 1981, 85). Our hedonic equation for renter-occupied housing therefore examines how the current market price of the flow of (rental) housing services varies with dwelling age. Rents might be expected to change as the flow of housing services decreases as the unit deteriorates. The market value of owner-occupied residential real estate, on the other hand, reflects the present value of future housing services as well as current services. Hence, changes in any of the determinants of present value will have a significant impact on the current market value of owner-occupied housing.

Viscosity and Thermal Conductivity of Nitrogen for a Wide Range of Fluid States

Abstract: The viscosity and the thermal conductivity of fluid nitrogen were critically evaluated and correlated on the basis of a comprehensive literature survey. Recommended values were generated in a temperature range from 70 to 1100 K and pressures up to 100 MPa using the residual concept. To retain consistency with the IUPAC Thermodynamic Tables, the same thermodynamic key data were used. Additionally, a so‐called transport equation of state was established that makes it possible to achieve a unified representation of the viscosity and thermal conductivity in terms of pressure and temperature.

Models of viscoplasticity some comments on equilibrium (back) stress and drag stress

Abstract: Phenomenological and microstructural motivations for the terms appearing in the title are found in a literature survey. Although the interpretations differ with various investigators a strong tendency is observed to consider plastic flow as rate dependent. It is stated that plastic strain takes time to develop and the existnce of an equilibrium stress is postulated at which plastic strain is fully developed. It is similar to the back stress used in materials science. The drag stress introduced from microdynamical studies performs the same function as the isotropic variable in plasticity. Most of the theories that describe the transient and steady-state behavior of metallic alloys make the inelastic strain rate a function of the over (effective) stress. It is shown that this concept has considerable advantages in the modeling of changes of viscous (time- or rate-dependent) and plastic (time- or rate-independent) contributions to hardening that are observed in cyclic loading and dynamic plasticity.

Dam-breach flood wave models

Abstract: Significant advances in the state‐of‐the art of dam‐breach flood wave modeling have occurred during the past decade. A comparative evaluation of several leading models representative of the current state‐of‐the‐art included a comprehensive literature survey and application of the selected models to several case study data sets. A dynamic routing model should be used whenever obtaining a maximum practical level of accuracy is required and adequate manpower, time, and computer resources are available. The National Weather Service (NWS) Dam‐Break Hood Forecasting Model (DAMBRK) is the optimal choice of model for most practical applications. Some applications require the capability to perform an analysis as expeditiously as possible. The NWS Simplified Dam‐Break Flood Forecasting Model (SMPDBK) is the optimal choice of model for most of these types of applications.

Bowel perforation in Hirschsprung's disease

Abstract: A review of the medical records of 45 infants less than 1 year old with Hirschsprung's disease identified two (4.4%) who presented with bowel perforation. A literature survey was done to evaluate the relationship between bowel perforation of the bowel early in the course of Hirschsprung's disease indicates that: the infant under 4 months old is at the greatest risk; the majority of cases (62%) were associated with long-segment or total colonic Hirschsprung's disease; the most common sites of perforation were the proximal colon (68%) and appendix (17%); in cases with a short or intermediate length of aganglionic bowel, the perforation was proximal to or at the site of transition, but in 84% of infants with total colonic aganglionosis the perforation was situated in aganglionic bowel. Hirschsprung's disease should be a prime differential consideration in a young infant with penumoperitoneum caused by distal bowel perforation.

Gold Leaching from Refractory Ores—Literature Survey

Abstract: This review is essentially an overview of the pretreatment processes for the refractory gold ores available in the recent literature. When gold is finely disseminated in sulphides, arsenosulphides, tellurides, carbonaceous and clayey materials direct alkaline cyanidation is not effective for gold extraction. However, pretreatment processes involving thermal oxidation, such as roasting, chemical oxidation, such as acid leaching, acid or alkaline pressure leaching; or biological oxidation such as bioleaching with T. Ferrooxidans liberates gold from refractory minerals. Gold is then recovered from the oxidized mass by alkaline cyanidation. Beside pretreatments, direct gold recovery from carbonaceous gold ores or concentrates with thiourea or CIL leach process is also feasible. Finally, some critical comments have been made to all the major pretreatment processes; and some recommendations for further R&D efforts have been suggested.

A literature survey on distributed discrete event simulation

Abstract: Much literature over the past decade has examined using multiprocessors to increase the speed and lower the cost of discrete event simulation. Three orthogonal approaches have been suggested, using simulation parallelism in support functions, in model functions and on the application level. This overview brings together these past approaches into a new framework wherein all three can be used simultaneously and suggests several promising research areas.

Probability density distribution in turbulent wall boundary layer flows

Abstract: The present paper provides a summary of a literature survey on statistical properties of wall boundary-layer flows. Existing knowledge on the subject and the authors’ own investigations are described that were initially carried out to yield mean and fluctuating flow properties in turbulent wall boundary layers at high Reynolds numbers. From these investigations, instantaneous velocity information resulted which was processed to yield local velocity information in the form of mean velocity and probability density distributions of the turbulent velocity fluctuations. It is shown that the latter obey a general analytical distribution law. Hence, it is possible to describe probability density distributions in turbulent boundary-layer flows in an analytical form. In the sublayer as well as in the wake region of the boundary layer, a simple form of the general distribution, known as the hyperbolic function, describes the probability density distributions of the velocity fluctuations very well. The latter curve contains four parameters whereas the general distribution requires seven parameters for describing the entire probability density distribution of turbulent velocity fluctuations. The distributions of these parameters across a wall boundary-layer flow are given in the paper.

Boundary elements in shape optimal design of structural components

Abstract: The shape optimal design of shafts and two-dimensional elastic structural components is formulated using boundary elements. The design objective is to maximize torsional rigidity of the shaft or to minimize compliance of the structure, subject to an area constrain Also a model based on minimum area and stress constraints is developed, where the real and adjoint structures are identical, but with different loading conditions. All degrees of freedom of the models are at the boundary and there is no need for calculating displacements and stresses in the domain. Formulations based on constant, linear and quadratic boundary elements are developed. A method for calculating accurately the stresses at the boundary is presented, which improves considerably the design sensitivity information. It is developed a technique for an automatic mesh refinement of boundary element models. The corresponding nonlinear programming problems are solved by Pshenichny’s linearization method. The models are applied to shape optimal design of several shafts and elastic structural components. The advantages and disadvantages of the boundary element method over the finite element technique for shape optimal design of structures are discussed with reference to applications. A literature survey of the development of the boundary element method for shape optimal design is presented.

A Literature Review on Korean Rice-cakes

Abstract: A literature survey on traditional Korean rice-cakes was made in order to identify the historical background and the state of scientific understanding on these products. Korean rice cakes can be classified into 5 groups depending on the processing methods; steamed (Jeung-byung), pounded (Do-byung), shaped and steamed or boiled (Dan-ja), fried (Yu-Jeon-byung) and fermented and steamed (Yi-byung). They are further divided into varieties by the raw materials used, coating materials and shape. The recipe and processing characteristics of 5 groups of Korean rice-cake were discussed and the scientific findings on these products were reviewed.

Genetic variation of energy metabolism in poultry.

Abstract: A literature survey was performed to quantify the variation between poultry strains and between individual animals within strains with respect to some energy metabolism parameters: metabolizability of dietary gross energy (ME %), net energy for maintenance (NEm), heat increment of maintenance (HIm), and heat increment of production (HIprod). Both laying hens and growing chicks were studied.

The effect on artifact materials of the fumigant ethylene oxide and freezing used in insect control

Abstract: The literature survey on the effects of ethylene oxide on artifact material shows explicitly that there are potential changes in materials of artifacts on fumigation with ethylene oxide, e.g. chemical solubility, pH, adsorptive ability, and strength characteristics, as well as introducing humectants and products of ethylene oxide. Ethylene oxide, and its product ethylene glycol, which may form in artifact materials, are hazardous to man. They are mutagenic, carcinogenic and toxic, and difficult to monitor. Freezing of artifacts under specific conditions, and using specific procedures has been recommended as an alternative. The literature survey on the effects of freezing on materials that would be found in artifacts shows that there are potential water hazards which can easily be prevented. Bound water in dry artifact material, and water in damp materials in capillaries less than 30u will not form ice crystals at -20°C. Condensation caused by reduced holding capacity of air or warm air cooling adjacent to cold objects can be prevented. Freezing should not be used for non-adsorptive materials. Physical and dimensional changes are minimal at the recommended -20°C. Essential procedures for freezing artifacts are listed. -- AATA

Indicators of Institutional Achievement: Some Theoretical and Empirical Considerations.

Abstract: This article outlines a number of general approaches to organisational effectiveness, and three approaches to effectiveness in the more specific field of higher education. The literature survey is used to derive a broad framework suggestive of the main causal relationships likely to exist between various areas of institutional achievement, and this framework is used as a background to discussion of empirical evidence. Empirical findings in the field of institutional achievement are sparse and poorly interconnected. The article summarises findings from product portfolio matrix studies and Cameron's work on effectiveness, discusses some aspects of institutional management, and outlines some differences between British and American universities regarding the acquisition of funds. The article concludes with comments on some methodological aspects of assessing institutional achievement.

Relationships between road transport working conditions, fatigue, health and traffic safety

Abstract: The report contains a literature survey evaluating research on the relationship between working and driving hours and rest periods of professional road transport drivers, and fatigue, health and traffic safety. Indications for limitations on driving and working hours in order to protect drivers against health and traffic safety hazards are specifically looked for and evaluated. Only a few investigators have taken professional bus drivers as the subject of their study, the majority of the research concentrates on truck drivers. Hence, the results in this literature survey are limited to these drivers but in a general sense the conclusions are also applicable to bus drivers who work under the same conditions as truck drivers. Truck drivers in North America and Europe work very long days, between 12 and 14 hours on average, and approximately 60% of this time is spent driving the truck. In addition, their daily rest between consecutive working periods is relatively short. There is no clear evidence for a direct relationship between driving hours and accident occurrence. However, in one case a relationship between long working hours and accidents is reported. Accident risk in general appears to be 2.5 times higher for a driver who works over 13 hours per day than for a driver who works 10 hours or less. There is evidence that inadequate daily rest leads to drivers falling asleep at the wheel. However, no limits for the length of rest periods can be set without further research. Future research should concentrate on: (a) the influence of the number of working hours per week and the length of rest periods in between working periods on accident occurrence and health problems of professional road transport drivers; and (b) the circumstances surrounding the onset of fatigue. (TRRL)

Relationship between minimum exchangeable potassium and soil taxonomy

Abstract: Potassium is an essential element for plant growth and its importance in agriculture has been well recognized. With continuous cropping of a soil, exchangeable ? levels decrease to a minimum, steady‐state level if no ? is added. This minimum level is important to both modeling soil ? cycling and fertilizer ? recommendations, and it has been determined by field studies lasting from 2 to 10 years. Consequently, there is a need for estimation of minimum exchangeable ? levels for a wide range of soil types from soil physical and chemical properties. A literature survey provided 19 studies where minimum exchangeable ? had been measured and regression analysis was conducted on this data to determine predictive relationships. Minimum exchangeable ? is closely related to soil clay content (r2 from 0.66 to 0.99), however, regression constants varied from study to study. Improved correlations were obtained between minimum exchangeable ? and clay content when all the soils (22A, r2=0.69) were divided into 3...

Properties of concrete at very low temperatures: A survey of the literature

Abstract: This literature survey is focussed on the behaviour of concrete at very low temperatures down to -196°C. To give the reader some theoretical background, first the mechanisms of freezing and frost damage are discussed. Based on these mechanisms, reasonable explanations can be given for the characteristic behaviour of concrete under cryogenic conditions. The thermal deformation, the compressive and tensile strengths and the elasticity of concrete will be successively treated in separate Sections. Special attention will be paid to the effect of the mix proportions, moisture content, type of aggregate and thermal cycling on the behaviour of concrete. Finally, the cryogenic bond behaviour will be discussed. Particularly, the local bond stress-slip relationship will be analysed in more detail. Furthermore, the effect of low temperatures upon the crack width and spacings conclude this literature survey.