Correlations

The increasing wind power generation requires the updating of the computational tools that support decision making in the operation and planning of electric power systems. This work describes a methodology to model the spatial correlations among wind speeds probability distributions in probabilistic power flow. The proposed methodology is based on Nataf transformation and Monte Carlo Simulation. The proposed methodology is illustrated in case studies with the IEEE 24 bus test system, highlighting the importance of adequately considering such correlations.

This article focuses on the impact of international research collaboration on individual research productivity in 11 European countries. Research productivity and international publication co-authorship of “internationalists” and “locals” (or academics collaborating and not collaborating internationally) are compared. The article uses a micro-level (individual) approach and relies on the primary data collected in a comparable format through a survey from 17,211 European academics. In all countries and all clusters of academic fields studied, international collaboration in research is strongly correlated with substantially higher research productions. Internationalization increasingly plays a stratifying role, though: More international collaboration tends to mean higher publishing rates and those who do not collaborate internationally may be losing more than ever before in terms of resources and prestige in the process of “accumulative disadvantage.” The competition is becoming a pe...

Society’s expectations of farmers in relation to their environmental performance are ever increasing, in general terms and in response to regional challenges. One tool for achieving environmental improvements in agriculture is the design and promotion of region-specific ‘best management practices’ (BMPs). BMPs are conservation practices aimed at reducing diffuse source pollution from agricultural lands and thus improving end-of-catchment water quality. A suite of grazing BMPs was developed for the Burdekin River catchment in Australia, which drains into the Great Barrier Reef lagoon. BMPs were developed in a consultative fashion but without explicit consideration of key factors that influence adoption, in particular farmers’ goals and risk perceptions. This paper utilises the data from a survey of 94 graziers in the Burdekin River catchment to explore whether and to what extent motivations and risk perceptions influence the adoption of BMPs. The results demonstrate clear correlations between both motivations, and risk attitudes, and the adoption of BMPs. In particular, strong conservation and lifestyle motivation translates into intrinsic motivation for adoption of conservation practices, while option values prevent strongly economically/financially motivated farmers from adopting in the absence of external incentives. We conclude that a sound understanding of farmers’ motivations and risk attitudes is required—in a regional, industry and environmental context—to tailor public investments aimed at providing relevant improvements in the environmental performance of agriculture.

Accurate determination of the crude oil PVT properties is essential for solving many reservoir engineering, production engineering, and surface production and operational problems. A large number of PVT correlations for oil exist in the petroleum literature and numerous studies are also present for with data favoring one correlation over the other. In the absence of PVT data from laboratory experiments, it is often difficult to choose which correlation to use to calculate different PVT properties. We approached this problem in two ways. First, we developed an expert system that checks the input parameters (e.g. reservoir parameters) against the valid ranges of input data for different correlations, and then recommends which correlations to use for specific input parameters. Second, we tested all available PVT correlations for black oil on a database of selected 35 Egyptian crudes to develop guidelines on which correlations to use for each PVT property for the specific range of input data. These specific crudes were selected to allow testing of those guidelines on a wide range of reservoir input data for black oils. Our database included oils with oAPI ranging from 17 to 51, gas-oil-ratios of 8 to 7,800 scf/STB, formation volume factor at bubble point of 1.04 to 4.47 bbl/STB, bubble point pressures of 60 to 4,739 psia, and reservoir temperatures of 40 to 270 ◦F.
The present work included 13 bubble points, 6 solution-gas-oil ratio, 14 formation volume factors, 13 oil compressibilities, 14 dead oil viscosities, 9 saturated oil viscosities, 10 under saturated oil viscosities ,12 under-saturated densities, 2 total formation volume factors and 2 saturated density correlations.
Based on this study, guidelines for selecting an appropriate correlation for PVT oil properties are introduced .These guidelines are recommended in programming of PVT correlations regardless of their geographic origin

Description/Abstract This manual focuses on the needs of engineers involved in the geotechnical design of foundations for transmission line structures. It also will serve as a useful reference for other geotechnical problems. In all foundation design, it is necessary ...

Yamuna river pollution has been extensively studied with regard to some selected parameters in five locations at Palla, Nizamuddin Midstream, Nizamuddin Quarter Stream, Agra Canal Midstream, and Agra Canal Quarter Stream in Delhi, India. Seasonal and location-wise variation of pollutants namely dissolve oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), total Kjeldahl nitrogen (TKN), ammonia (AMM), total coliform and fecal coliform were studied for 6 years during the period of 2000–2005. The study results revealed the lowest level of pollution during monsoon. The statistical analysis revealed a positive correlation between DO, BOD, COD, TKN, and AMM.

An accurate model for the estimation of the drag coefficient of a falling sphere is essential for different theoretical analyses and engineering applications. Ramírez (2017) summarized relationships of the frictional drag coefficient and presented the historical chronological sequence of the coefficient. While the author’s intention is laudable, this note discuss some important points in the subject matter, which is useful for the chemical engineers.

Rhinocerotid fauna from the Orleanian (MN3-5) of the Garonne and Loire basins are revised. Twelve taxa, with seven asiatic migrants, are recognized and connected to the biostratigraphical context. New correlations are established between both areas. Three rhinocerotid associations are characterized for the Orleanian of the studied basins.Les faunes de rhinocérotidés orléaniens (MN3-5) des bassins de la Garonne et de la Loire sont révisées. Les douze taxons, dont sept migrants asiatiques, sont ensuite replacés dans leur contexte biostratigraphique. De nouvelles corrélations sont établies entre les gisements des deux bassins. Enfin, trois associations-marqueurs de rhinocérotidés sont caractérisées pour l'Orléanien des régions étudiées.

February 1996Inflation limits economic growth by reducing the efficiency of investment rather than its level. An effective way of achieving low inflation is to establish an independent central bank.De Gregorio reviews the theory and evidence on inflation and growth and provides ...

This paper presents first a discussion on the status of the subdivisions of the European Neogene mammal chronology and second, it synthesizes all available magnetostratigraphic data from Europe to provide chronological framework for mammal localities, mammalian events and mammalian biochronologic units of the European Neogene.Because of the lack of their rock equivalents, the subdivisions of the European Neogene, based on mammals, have not attained the stage status in terms of reliability, except the Vallesian and Turolian. Therefore they are designated as the European Land Mammal Ages (ELMA).Magnetostratigraphic data on mammal-bearing deposits in Europe is still scarce in time and space; consequently, it is not yet possible to correlate accurately all ELMA and MN zones with the geomagnetic polarity time-scale (GPTS). Nevertheless, several studies dealing with mammal localities (and their deposits) around the Oligocene/Miocene boundary, in the middle and late Miocene provide reliable correlations of some ELMA and MN zone boundaries. Thus, the calibration of the Oligocene/Miocene boundary at the base of Chron C6Cn.2n is in agreement with its age in marine deposits. The well-known Hipparion Datum (Astaracian/Vallesian boundary) is now dated as about 10.8 Ma, occurring slightly above the base of Chron C5n.2n.This paper also reviews magnetostratigraphic correlations of some late Miocene and Pliocene mammal localities in the Paratethys area. Taking into account the chronological assessments in other parts of Europe for some key mammalian events, new correlations with the GPTS have been proposed for these localities. Thus some new ages are suggested for the late Miocene and Pliocene Paratethys stages.