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In order to improve the effect of injection–production coupling development to improve crude oil recovery in complex fault-block reservoirs, we carried out a physical simulation experiment based on a sandpack model of transforming water-driven development into injection–production coupling development and quantitatively evaluated the influence of rounds of injection pressure coupling on the crude oil mobilization in reservoirs with different permeability levels and on oil recovery. Meanwhile, the characteristics of residual oil were studied via a numerical simulation method. The mechanism of increased oil production via injection–production coupling development was revealed by analyzing the water and oil contents, formation pressure, and streamline fields through the establishment of mechanism models. The results of the physical experiment show that injection–production coupling can improve the recovery effect of medium- and low-permeability reservoirs by 55.66%. With an increase in the injection pressure, the oil recovery percentage of the low-permeability sandpack model at 20 MPa is 100%, and this study finds that injection–production coupling is the main way to develop the recoverable oil in a low-permeability reservoir. The numerical simulation results show that among the four remaining oil distribution types (interwell-enriched, low-permeability zone-enriched, well network imperfection, and mismatch between injection and production), the interwell-enriched type of the remaining oil reserves accounts for the highest proportion (48.52%). The simulation results of the mechanism model show that water-driven development easily leads to streamline solidification, resulting in ineffective circulation of the injected water. Compared with conventional water-driven development, the pressure propagation range is significantly increased in injection–production coupling development. The reservoir streamline distribution is more continuous and uniform, and the flooding wave is wider in volume and range. This research provides a theoretical basis for the injection–production coupling technology policy in complex fault-block reservoirs. [ABSTRACT FROM AUTHOR]

Background: The widespread use and misuse of antimicrobials are the major driving factor for antimicrobial resistance (AMR) that threatens the health of human beings globally. Thus, monitoring antimicrobial consumption at national level is crucial to prevent and contain AMR. Nevertheless, there is no well-established system for recording and reporting of antimicrobial consumption in Ethiopia. Hence, the national antimicrobial consumption survey was conducted to generate evidence for decision-making on the appropriate use of antimicrobials in Ethiopia and tackle AMR. Methods: All imported and locally manufactured antimicrobials from 2017 to 2019 were from the Ethiopian Food and Drug Authority and local manufacturers database, respectively. Data were collected and analyzed descriptively in accordance with the World Health Organization (WHO) Anatomical Therapeutic Chemical (ATC) and defined daily doses (DDD) classification and methodology. Results: The average DDD/1,000 inhabitants for all antimicrobials was 15.36. The DDD/1,000 inhabitants fell down sharply from 37.03 in 2017 to 4.30 in 2018, before slightly rising to 4.75 in 2019. The majority of the consumed antimicrobials were comprised of oral antimicrobials (98.6%), while parenteral antimicrobials made up 1.4%. Tetracyclines (35.81%), fluoroquinolones (20.19%), macrolides (13.92%), antiretrovirals (10.57%), and cephalosporins (9.63%) were the most frequently consumed classes of antimicrobials during the three years period. About 75.83% of the consumed antimicrobials fall under the WHO AWaRe classification and 67.87% of antimicrobial consumption was from the WHO Access class medications, with Watch and Reserve classes accounting for 32.13% and <1%, respectively. Similarly, about 86.90% of the antimicrobials fall under the Ethiopian AWaRe classification, with Access, Watch, and Reserve accounting for 87.73%, 12.26%, and <1%, respectively. Conclusion: Due to the peculiarities of our settings, our findings may have some similarities and differences with similar studies from other countries. Hence, we recommend for all concerned bodies to work collaboratively to improve monitoring of antimicrobial consumption at different levels of the Ethiopian healthcare tier system. Future work is necessary to establish a strong system of reporting of antimicrobial consumption patterns in Ethiopia. [ABSTRACT FROM AUTHOR]

The western Baltic Sea cod (WBC) stock is at historically low levels, mainly attributed to high fishing pressure and low recruitment. Stable stock assessment metrics suggested recovery potential, given appropriate fisheries management measures. However, changing environmental conditions violate stability assumptions, may negatively affect WBC, and challenge the resource management. The present study explored 42 years of changes in WBC biological parameters. WBC body condition gradually decreased over the last decades for juveniles and adults, with a rapid decrease in recent years when a single cohort dominated the overfished stock. The hepato-somatic index and the muscle weight decreased by 50% and 10% in the last 10 years, respectively, suggesting severely decreasing energy reserves and productivity. The changes in energy reserves were associated with changes in environmental conditions (increase in bottom water temperature, expansion of hypoxic areas during late summer/autumn), and changes in diet composition (less herring). A key bottleneck is the warming and longer-lasting summer period when WBC, trapped between warmed shallow waters and hypoxic deeper waters, have to mobilize energy reserves to account for reduced feeding opportunities and thermal stress. Our results suggest that stock recovery is unlikely to happen by fisheries management alone if environmental trajectories remain unchanged. [ABSTRACT FROM AUTHOR]

This paper proposes a comprehensive methodology for determining the converter droop settings to ensure the voltage security in a multi-terminal direct current (MTDC) grid. The novelty lies in the introduction of the concept of over- and under-voltage containment reserves in analogy to the frequency containment reserves in AC systems. This not only gives a distinction of the contribution between the converters in rectifying and inverting modes, but also significantly facilitates the sizing of the necessary amount of reserves within their available headroom capacity of power. In particular, the constraints of converter outages, converter rating, and DC voltage deviations are all taken into account in the design of reserves. The effectiveness of the proposed approach is demonstrated by a contingency power flow analysis algorithm and EMT simulations of a four-terminal MTDC grid. [ABSTRACT FROM AUTHOR]

Global warming is increasing the vulnerability of ecosystems, especially in peninsular Spain. Biosphere Reserves are internationally protected areas that seek to protect biodiversity and, at the same time, promote sustainable development. Evaluating these protected areas is essential to verify environmental changes and establish priorities in their management. In this work, we have studied the time trends of NDVI in the high mountain Biosphere Reserves of Spain from 2001 to 2016 to check if the trend patterns are associated with some environmental variables. Significant differences were found between NDVI trends and high mountain Biosphere Reserves. Firstly, significant positive trends in NDVI were observed when analysing both reserves together. However, significant differences were found between the two reserves. The Ordesa-Viñamala Reserve shows higher positive NDVI trends and lower negative trends, while this pattern is reversed in Sierra Nevada. We observed how the fluctuations in temperature and drought due to climate change have already negatively affected the Mediterranean reserve (Sierra Nevada). In contrast, the alpine reserve (Ordesa-Viñamala) maintains positive NDVI trends. This study helps to close the gap in information related to Biosphere Reserves, which gives value to the work that is being carried out by the local communities that make up them, generating statistically significant results that Biosphere Reserves are protected areas that help us understand how to manage and govern socioecological systems sustainably. • The study assesses NDVI trend in the Spanish high mountain Biosphere Reserves. • We analysis the association between NDVI trends and environmental variables. • Significant differences in NDVI trend frequency found between the reserves. • Climate change is having effects on reserves NDVI trends. • Trend data is key to ensuring reserves take into account in political decisions. [ABSTRACT FROM AUTHOR]

The complex pattern of gold production in Canada, which differs from the classic Hubbert´s curve, is modeled, and a short-term forecast is made, via the Fundamental Equation of Mineral Production (FEMP). For intervals of time with a variable production to reserves ratio, a discrete piecewise version of the equation updates the reserves and the Production to Reserves Ratio (PRR) by units of time. These piecewise linear portions of the PRR correspond to sub-cycles of rising and declining production embedded in the overall history of production. This version of the FEMP allows modelling of any pattern of mineral production at a universal range of scales. The Hubbert´s linearization indicates the official account of reserves underestimates the real amount of gold resources in Canada. The equivalence between the Hubbert's formula and the FEMP is introduced. The Hubbert curve is shown as a case study of the Fundamental Equation, featured as the product of a quadratic function of the cumulative production and a rational function of the PRR with time. The forecast for Canada's current gold production illustrates the metal output is about to peak with an all-time record high in the near future, unless new findings or influential global economic factors are introduced (i.e., a sharp and sustained growth of gold demand from regional markets), allowing an increase of the slope of the linear function featured by the PRR of the FEMP-based model. [ABSTRACT FROM AUTHOR]

The article describes a method for estimating the U.S. government's overall programmatic credit risk exposure that recognizes the covariance across its guarantee programs. The government is urged to have a capital reserve for covering aggregate losses that is lower than the sum of the capital reserves appropriate for each separate guarantee program. Also presented is evidence of loss distributions of government-sponsored enterprises (GSEs) in the context of Fannie Mae and Freddie Mac.

The AquaCrop simulation model, originally designed for annual crops, is expanded here to simulate alfalfa, a perennial forage crop. A new routine was added to the model to mimic the assimilate partitioning between above and below-ground plant parts to account for the utilization of reserves in Spring and for their storage in the Fall. The simulation of the transfer of assimilates requires only three extra crop parameters which makes the model also easy to calibrate. To evaluate the model, yield data collected in Louvain-La-Neuve (Belgium), Isparta (Turkey), and Ottawa (Canada) for different alfalfa cultivars, various years and field and irrigation management strategies were used. To assess the accuracy and robustness of the simple assimilate remobilization process, simulations were run for the three different environments with a common set of crop parameters which were parameterized. The dispersion between the observed and simulated cumulative dry above-ground biomass during the growing cycle was small (r² = 0.97; nRMSE = 11%; Nash-Sutcliffe model EF = 0.97), and a systematic over- or underestimation by the model was not observed (Willmott's index of agreement, d = 0.99). When evaluating the goodness of fit of the 81 individual harvest events, the results were still very satisfactory although the nRMSE doubled. The simulations indicated that the AquaCrop model adapted to perennial crops and with a novel storage-remobilization routine, could predict well alfalfa yields in various climates and environments, with and without water and fertility stress, and for three different alfalfa cultivars. • The AquaCrop simulation model is expanded to simulate perennial forage crops. • A simple routine describes the transfer of assimilates between the above ground biomass and the below-ground storage organs. • Variations in partitioning along the season was simulated by increasing or reducing the crop water productivity. • Simulations were run with a common set of crop parameters for different years, alfalfa cultivars, climates, and environments. • The simulations indicated that AquaCrop can well predict the total yield of alfalfa that can be expected in various environments. [ABSTRACT FROM AUTHOR]

Why have emerging market economies (EMEs) been stockpiling international reserves? We find that motives have varied over time; vulnerability to current account shocks was relatively important in the 1980s but, as EMEs became more financially integrated, factors related to the magnitude of potential capital outflows gained importance. Reserve accumulation as a by-product of undervalued currencies has also become more important since the Asian crisis. Correspondingly, using quantile regressions, we find that the reason for holding reserves varies according to the country's position in the global reserves distribution. High-reserve holders, who tend to be more financially integrated, are motivated by insurance against capital account rather than current account shocks and are more sensitive to the cost of holding reserves than are low-reserve holders. Currency undervaluation is a significant determinant across the reserves distribution, albeit for different reasons. [ABSTRACT FROM AUTHOR]

China is both a major trading partner of the United States and the largest official holder of U.S. assets in the world. The value of Chinese foreign exchange reserves peaked at just over $4 trillion in June 2014 but has since declined to $3.19 trillion (as of August 2016). This very large decline in foreign exchange reserves is unprecedented, and some analysts have speculated that continued sales of these (mostly U.S.) assets might significantly impact the U.S. and global economies. This article explains the reasons for this large decline in official assets, China's available policy choices, and how these choices could affect the U.S. economy. [ABSTRACT FROM AUTHOR]

We present evidence from 260,000 online auctions of second-hand cars to identify the impact of public reserve prices on auction outcomes. We exploit multiple discontinuities in the relationship between reserve prices and vehicle characteristics to present causal regression-discontinuity estimates of reserve price impacts. We find an increase in reserve price decreases the number of bidders, increases the likelihood the object remains unsold, and increases expected revenue conditional on sale. We then combine these estimates to calibrate the reserve price effect on the auctioneer's ex ante expected revenue. This reveals the auctioneer's reserve price policy to be locally optimal. ( JEL D44, L11, L62) [ABSTRACT FROM AUTHOR]

The frequent best practice for managing large low-grade run-of-mine (ROM) stockpiles is to average the entire stockpile to only one grade. Modern ore control and mineral processing procedures need better precision. Low-precision models hinder the ability to create a digital mine-to-mill model and optimize the holistic mining process. Prior to processing, poorly characterized stockpiles are often drilled and sampled, despite there being no geological reason for relationships between samples to exist. Stockpile management is also influenced by reserve accounting and lacks a common operational workflow. This paper provides a review of base and precious metal run-of-mine (ROM) pre-crusher stockpiles in the mining industry, and demonstrates how to build a spatial model of a large long-term stockpile using fleet management system (FMS) data and geostatistical code in Python and R Studio. We demonstrate a framework for modelling a stockpile believed to be readily workable for most modern mines through use of established geostatistical modelling techniques applied to the type of data generated in a FMS. In the method presented, each bench of the stockpile is modeled as its own geological domain. Size of dump loads is assumed to contain the same volume of material and grade values that match those of the grade data tracked in the FMS. Despite the limitations of these inputs, existing interpolation techniques can lead to increased understanding of the grade distribution within stockpiles. Using the framework demonstrated in this paper, engineers and stockpile managers will be able to leverage operational data into valuable insight for empowered decision making and smoother operations. [ABSTRACT FROM AUTHOR]

With the depletion of traditional energy resources, the share of heavy-oil production has been increasing recently. According to some estimates, their reserves account for 80% of the world's oil resources. Costs for extraction of heavy oil and natural bitumen are 3–4 times higher than the costs of extracting light oil, which is due not only to higher density and viscosity indicators but also to insufficient development of equipment and technologies for the extraction, transportation, and processing of such oils. Currently, a single pipeline system is used to pump both light and heavy oil. Therefore, it is necessary to take into account the features of the heavy-oil pumping mode. This paper presents mathematical models of heavy-oil flow in oil-field pipelines. The rheological properties of several heavy-oil samples were determined by experiments. The dependencies obtained were used as input data for a simulation model using computational fluid dynamics (CFD) methods. The modeling condition investigates the range of shear rates up to 300 s−1. At the same time, results up to 30 s−1 are considered in the developed computational models. The methodology of the research is, thus, based on a CFD approach with experimental confirmation of the results obtained. The proposed rheological flow model for heavy oil reflects the dynamics of the internal structural transformation during petroleum transportation. The validity of the model is confirmed by a comparison between the theoretical and the obtained experimental results. The results of the conducted research can be considered during the selection of heavy-oil treatment techniques for its efficient transportation. [ABSTRACT FROM AUTHOR]