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- AghaKouchak, Amir, et al.
(författare)
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Anthropogenic Drought : Definition, Challenges, and Opportunities
- 2021
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Ingår i: Reviews of geophysics. - : John Wiley & Sons. - 8755-1209 .- 1944-9208. ; 59:2
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Forskningsöversikt (refereegranskat)abstract
- Traditional, mainstream definitions of drought describe it as deficit in water-related variables or water-dependent activities (e.g., precipitation, soil moisture, surface and groundwater storage, and irrigation) due to natural variabilities that are out of the control of local decision-makers. Here, we argue that within coupled human-water systems, drought must be defined and understood as a process as opposed to a product to help better frame and describe the complex and interrelated dynamics of both natural and human-induced changes that define anthropogenic drought as a compound multidimensional and multiscale phenomenon, governed by the combination of natural water variability, climate change, human decisions and activities, and altered micro-climate conditions due to changes in land and water management. This definition considers the full spectrum of dynamic feedbacks and processes (e.g., land-atmosphere interactions and water and energy balance) within human-nature systems that drive the development of anthropogenic drought. This process magnifies the water supply demand gap and can lead to water bankruptcy, which will become more rampant around the globe in the coming decades due to continuously growing water demands under compounding effects of climate change and global environmental degradation. This challenge has de facto implications for both short-term and long-term water resources planning and management, water governance, and policymaking. Herein, after a brief overview of the anthropogenic drought concept and its examples, we discuss existing research gaps and opportunities for better understanding, modeling, and management of this phenomenon.
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- Derakhshan, M., et al.
(författare)
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The pedagogical challenges of creating information literate librarians
- 2017
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Ingår i: Library Review. - : Emerald Group Publishing Ltd.. - 0024-2535 .- 1758-793X. ; 66:6-7, s. 570-583
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: This study aims to investigate the challenges of developing information literacy (IL) competencies and approaches to overcome the challenges among library and information science (LIS) students in Iran. Design/methodology/approach: Taking an exploratory approach, the study used semi-structured interviews to gather the data. Using the 2000 ACRL standards as a framework, the fieldwork questions were designed around the five areas of IL competencies. A total of 15 academics teaching 18 different LIS courses from six universities were interviewed. They were asked the challenges they faced in teaching these competencies and the approaches they took or suggested in overcoming the challenge(s). A thematic approach was used to analyze the data. Findings: Some of the challenges for students mentioned by the interviewees were ambiguity about the discipline, inability to match subject relevance with appropriate sources of information and lack of familiarity with databases. Research limitations/implications: This study is limited to LIS academics; studying students’ reflections can bring broader perspectives to IL education in LIS programs. Owing to the nature of the design of this study, which is a single case study, the teaching experiences of IL are limited to the ones which emerged and were addressed in the context of the case. Although the case selection was made in a way that can be representative of the “general” in the “particular” bounded system of the case (Stake, 1998), studying more cases could certainly have brought broader perspectives to IL which could have been to wider contexts. Originality/value: The results of this study contribute to our understanding of challenges in teaching IL in the LIS discipline, an area that has not been researched directly. This contributes to IL teaching in disciplinary areas and it brings new perspectives to the elements of IL teaching which emerged from the experiences of people who are directly experienced in the context of the discipline.
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- Hassanzadeh, Ahmad, et al.
(författare)
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Estimation of flotation rate constant and particle-bubble interactions considering key hydrodynamic parameters and their interrelations
- 2019
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Ingår i: Minerals Engineering. - : Elsevier BV. - 0892-6875. ; 141
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Tidskriftsartikel (refereegranskat)abstract
- Particle-bubble sub-processes cannot be directly and physically obtained in froth flotation due to the complexity of the process as well as numerous and dynamic interactions of particles and bubbles in an extremely intensive turbulent condition. Therefore, over the last three decades, two fundamental model configurations have been used as an only solution for prediction of particle-bubble collection efficiencies (Ecoll). Additionally, the relative intensity of the main flotation parameters on flotation rate constant, particle–bubble interactions together with their interrelations is not adequately addressed in the literature. The present study attempts in two separate phases to overcome these difficulties. In the first stage, prediction and evaluation of particle-bubble sub-processes are critically discussed by categorizing them in two configurations. The analytical models (approach I) commonly applied generalized Sutherland equation (EcGSE), modified Dobby–Finch (EaDF) and modified Schulze stability (EsSC) models. The second approach, numerical models, utilized Yoon–Luttrell (EcYL), Yoon–Luttrell (intermediate) (EaYL) and modified Schulze stability (EsSC) models. In the second stage, relative intensity and interrelation of key effective hydrodynamic parameters on the probability of particle–bubble encounter (Ec) and flotation rate constant (k) are obtained and optimized by means of the response surface modeling (RSM) based on central composite design (CCD). Five key factors including particle size (1–100 µm), particle density (1.3–4.1 kg/m3), bubble size (0.05–0.10 cm) and bubble velocity (10–30 cm/s) together with turbulence dissipation rate (18–30 m2/s3) are considered in order to maximize the responses including the k and Ec. The results obtained show that the Ecoll calculated by numerical techniques (configuration (II)) is greater than that of analytical approaches (configuration (I)) due to assumptions involved in using Yoon–Luttrell collision and attachment models. It is also found that under the conditions studied, particle size and bubble velocity are the most effective factors on Ec and k, respectively. Furthermore, not only the relative significance of factors on Ec and k but also the interrelation of cell turbulence and bubble size as well as bubble velocity and turbulence are shown to be inconsistent in the literature and thus require further studies. We briefly reported the main long-standing challenges in flotation kinetic modeling and emphasized on a serious need for fulfilling lack of physical observations. Finally, the presented analyses with respect to three-zone model offer a new concept for the extension of common flotation modeling approach using analytical and numerical techniques.
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- Hassanzadeh Moghimi, Farzad, et al.
(författare)
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Aggregator-Enabled Prosumers' Impact on Strategic Hydro-Thermal Operations
- 2023
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Ingår i: Proceedings of the Annual Hawaii International Conference on System Sciences. - 9780998133164 ; , s. 2693-2702
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Konferensbidrag (refereegranskat)abstract
- Climate packages envisage decarbonization of the power system and electrification of the wider economy via variable renewable energy (VRE). These trends facilitate the rise of aggregator-enabled prosumers and engender demand for flexibility. By exploiting conducive geography, e.g., in the Nordic region, hydro reservoirs can mitigate VRE's intermittency. Nevertheless, hydro producers may leverage this increased need for flexibility to exert market power through temporal arbitrage. Using a Nash-Cournot model, we examine how aggregator-enabled prosumers with endogenous loads and VRE capacity interact with other agents to affect market outcomes. Based on Nordic data, we find that hydro producers enhance their market power by shifting their production away from periods in which prosumers are net buyers and "dumping" their output during periods in which prosumers are net sellers. Hence, jurisdictions that rely upon (hydro) storage to integrate VRE from prosumers will need to be wary of incumbent firms' incentives to manipulate prices.
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- Hassanzadeh Moghimi, Farzad, 1994-, et al.
(författare)
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Climate Policy and Strategic Operations in a Hydro-Thermal Power System
- 2023
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Ingår i: Energy Journal. - : International Association for Energy Economics (IAEE). - 0195-6574 .- 1944-9089. ; 44:5, s. 67-94
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Tidskriftsartikel (refereegranskat)abstract
- Decarbonisation of the Nordic power sector entails substantial variable renewable energy (VRE) adoption. While Nordic hydropower reservoirs can mitigate VRE output's intermittency, strategic hydro producers may leverage increased flexibility requirements to exert market power. Using a Nash-Cournot model, we find that even the current Nordic power system could yield modest gains from strategic reservoir operations regardless of a prohibition on "spilling" water to increase prices. Instead, strategic hydro producers could shift generation from peak to off-peak seasons. Such temporal arbitrage becomes more attractive under a climate package with a €100/t CO2 price and doubled VRE capacity. Since the package increases generation variability, lowers average prices, and makes fossil-fuelled plants unprofitable, strategic hydro producers face lower opportunity costs in shifting output from peak to off-peak seasons and encounter muted responses from price-taking fossil-fuelled plants. Hence, a climate package that curtails CO2 emissions may also bolster strategic hydro producers' leverage.
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- Hassanzadeh Moghimi, Farzad, et al.
(författare)
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Flexible supply meets flexible demand : prosumer impact on strategic hydro operations
- 2023
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Ingår i: Computational Management Science. - 1619-697X .- 1619-6988. ; 20:1
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Tidskriftsartikel (refereegranskat)abstract
- Ambitious climate packages promote the integration of variable renewable energy (VRE) and electrification of the economy. For the power sector, such a transformation means the emergence of so-called prosumers, i.e., agents that both consume and produce electricity. Due to their inflexible VRE output and flexible demand, prosumers will potentially add endogenous net sales with seasonal patterns to the power system. With its vast hydro reservoirs and ample transmission capacity, the Nordic region is seemingly well positioned to cope with such intermittent VRE output. However, the increased requirement for flexibility may be leveraged by incumbent producers to manipulate prices. Via a Nash-Cournot model with a representation of the Nordic region’s spatio-temporal features and reservoir volumes, we examine how hydro producers’ ability to manipulate electricity prices through temporal arbitrage is affected by (i) VRE-enabled prosumers and (ii) the latter plus a high CO22 price. We find that hydro reservoirs could exploit prosumers’ patterns of net sales to conduct temporal arbitrage more effectively, viz., by targeting periods in which prosumers are net buyers (net sellers) to withhold (to “dump”) water. Meanwhile, a higher CO22 price would further enhance hydro reservoirs’ market power because flexible price-taking thermal plants would be unable to ramp up production in order to counter such producers’ strategy to target VRE’s intermittency. Hence, in spite of a flexible demand side to complement additional intermittent VRE output, strategic hydro producers may still exacerbate price manipulation in a future power sector via more tailored exercise of market power.
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