Open Dam Research Articles

Statistical arbitrage trading across electricity markets using advantage actor–critic methods

In this paper, risk-constrained arbitrage trading strategies that exploit price differences arising across short-term electricity markets, namely day-ahead (DAM), continuous intraday (CID) and balancing (BAL) markets, are developed and evaluated. To open initial DAM positions, a rule-based trading policy using DAM and CID price forecasts is proposed. DAM prices are predicted using both technical indicator features and data augmentation methods, such as autoencoders and generative adversarial networks. Meanwhile, CID prices are predicted using novel features that are engineered from the limit order book. Using the forecasts, the direction of price movements is correctly predicted the majority of the time. To manage open DAM positions while optimising the risk-reward ratio, deep reinforcement learning agents trained using the advantage actor–critic algorithm (A2C) are employed. Evaluated across Dutch short-term markets, A2C yields profits surpassing those obtained using A3C and other benchmarks. We expect our study to benefit electricity traders and researchers who seek to develop state-of-art intelligent trading strategies.

ИЗУЧЕНИЕ ПЕРЕФОРМИРОВАНИЯ БЬЕФОВ НИЗКОНАПОРНЫХ ГИДРОУЗЛОВ В НИЗОВЬЯХ РАВНИННЫХ РЕК

The article presents the results of long-term field studies of the re-formation of water courses in the zone of the Takhiatash hydroelectric complex. It was noted that due to low water, for a significant part of the year, the Takhiatash dam worked with fully closed gates in all spans. In these years, the role of regulating the level regime of the shield dam is almost lost, and the end regulators of the main channels are regulated.
 The data of comparison of actual expenses, turbidity and back-up at the Takhiatash hydroelectric power plant with the calculated ones are presented. It is proved that sharp fluctuations in the water level in front of the dam and water intake into the channels lead to changes in the hydraulic and alluvial regime of the shield dam and channels. As the analysis of the survey of the riverbed cross-sections in the headwaters of the Takhiatash hydroelectric complex showed, in the initial period of operation, the bottom marks in the upper stream are increasing and the bottom marks in the lower stream are decreasing. Further years of operation (after 1982) were characterized by the stability of the flowing riverbed processes, that each characteristic year has its own level and consumption regime. It is noted that in high-water years there were no difficulties with water intakes, and the main difficulties are associated with the passage of flood flows through the shield dam. In recent years, there has been a rapid rise in the water level in the upper reaches, despite all the open dam gates, shipping locks and water intake structures, which are explained by the influence of the drifted streams on the capacity of the shield dam. It is proved that without any damage to the water intake during the growing season, it is possible to effectively flush the upstream with a constant decrease in the water intake coefficient - Kv < 0.55. Practically, this means for the Takhiatash hydroelectric unit that the flushing flow rate should not be lower than Q ≥ 250 – 300 m3/s.

Safety assessment method of steel protective structure against large-scale debris flow

Recently, steel pipe open type protective structures (steel open dams) have been damaged because of large-scale debris flow resulting from torrential rainfall based on abnormal climate. This article proposes a safety assessment method for the load-carrying capacity of a steel open dam against large-scale debris flow load (level II load) using the energy constant law. First, the safety assessment method of steel open dams is proposed that the ultimate strength must be larger than the required strength against the level II load, which is determined by using the energy constant law. Second, the load-carrying capacities of three types of steel open dams with different structural shapes against the front and eccentric debris flow loadings are investigated by a push-over analysis. Finally, the safety assessments on load-carrying capacities against the front and eccentric debris flow loading are confirmed and the strength reduction by the eccentric loading is examined for three steel open dams.

A safety verification method on load-carrying capacity of steel open dams

A safety verification method on load-carrying capacity of steel open dams

Failure analysis of steel open dam against an extreme boulder debris flow

This paper presents a failure analysis for a steel open-type Sabo dam (hereafter, steel open dam) against an extreme boulder debris flow load (hereafter, level II load) by a two-step analysis. The first step analysis is to estimate the level II load against the rigid wall by using the revised distinct element method (DEM). In the second step, the failure mechanism of a steel open dam is examined by using a dynamic elastic plastic analysis, in which the level II load-time relations obtained by the first analysis are multiplied by a reduction factor and then used. For the second step, the effects of the flange joint and dent deformation of the connection between column and beam are considered. Finally, a simple entire uniform load onto the steel open dam is proposed as a level II load model for the safety assessment.

Electrodialytic treatment of secondary mining resources for raw materials extraction: Reactor design assessment

The sustainability of mining activities is compromised due to the high amounts of mining residues generated that have to be disposed of, often in open dams, that may cause environmental deterioration, e.g. release of toxic elements to water supplies. These residues are, however, secondary resources of raw materials. In the case of Panasqueira mine, they even are a source of tungsten, considered a critical raw material. The present work aims to assess the electrodialytic process efficiency for raw materials extraction from Panasqueira mine residues. Experiments were performed with 2 and 3-compartment electrodialytic reactors, applying current intensities between 50 and 100 mA, from 4 to 14 days, and sample suspensions enhanced with NaCl or effluent. Additionally, control experiments with no current application were carried out. The results showed that a 3-compartment reactor operating at 100 mA, with NaCl as supporting electrolyte, presented the highest extraction of copper (13%), tin (10%), tungsten (13%) and arsenic (63%).

Using remote sensing to calculate floating photovoltaic technical potential of a dam’s surface

A dam with a hydroelectric power plant (HEPP) prevents flooding while generating electricity and providing controlled irrigation of agricultural land. An open dam surface causes a substantial loss in water resources over the course of a year due to evaporation. In this paper, the authors propose to occupy the idle dam area with a floating photovoltaic (FPV) solar power plant (SPP) to generate electrical energy and to conserve water by minimizing evaporation. Since the shoreline of a dam used for agricultural irrigation continually changes, the most critical challenge in installing a SPP is to determine the suitable area to be covered with FPV panels. In this study, the shoreline changes of the Demirköprü Dam in Manisa, Turkey, were monitored over 20 years from Landsat and Sentinel satellite images using the supervised classification in the Google Earth Engine. The minimum surface area of the dam was found to be 1,562.45 ha. Installing a 2.03 GWp FPV SPP horizontally on this surface and obtaining 3,328.33 GWh annual energy is feasible. Moreover, the FPV panels can prevent 28,231,026.90 m3 of water from evaporating. Approximately 7.82% of the water used for electricity production in 2019 can be recovered with the installation of this SPP.

Differential removal of human pathogenic viruses from sewage by conventional and ozone treatments.

Sewage contains a mixed ecosystem of diverse sets of microorganisms, including human pathogenic viruses. Little is known about how conventional as well as advanced treatments of sewage, such as ozonation, reduce the environmental spread of viruses. Analyses for viruses were therefore conducted for three weeks in influent, after conventional treatment, after additional ozonation, and after passing an open dam system at a full-scale treatment plant in Knivsta, Sweden. Viruses were concentrated by adsorption to a positively charged filter, from which they were eluted and pelleted by ultracentrifugation, with a recovery of about 10%. Ion Torrent sequencing was used to analyze influent, leading to the identification of at least 327 viral species, most of which belonged to 25 families with some having unclear classification. Real-time PCR was used to test for 21 human-related viruses in inlet, conventionally treated, and ozone-treated sewage and outlet waters. The viruses identified in influent and further analyzed were adenovirus, norovirus, sapovirus, parechovirus, hepatitis E virus, astrovirus, pecovirus, picobirnavirus, parvovirus, and gokushovirus. Conventional treatment reduced viral concentrations by one to four log10, with the exception of adenovirus and parvovirus, for which the removal was less efficient. Ozone treatment led to a further reduction by one to two log10, but less for adenovirus. This study showed that the amount of all viruses was reduced by conventional sewage treatment. Further ozonation reduced the amounts of several viruses to undetectable levels, indicating that this is a promising technique for reducing the transmission of many pathogenic human viruses.

Diurnal Patterns of Daily Activities Frequencies of White-Faced Whistling Duck (Dendrocygna viduata) in an Open Dam in Osogbo, Osun State, Nigeria

A non-invasive study on Dendrocygna viduata was carried out at a selected water body in Osogbo, Osun State, Nigeria to investigate daily, monthly and seasonal patterns in key diurnal activities frequencies to quantify diurnal activity budgets, visibility, and habitat preference. Observations of species activities were evaluated, during morning and afternoon, and twenty six (26) species of Dendrocygna viduata was recorded. Focal animal sampling method was used to select one individual at a time for observation and collection of activity data. Overlapping in collection of data was avoided carefully. Eight key diurnal activities of White-faced Whistling Duck were selected for the study. Normality test for all response variables was conducted using Shapiro-Wilk test for normality, and results was considered significant at 5% level. There was no significant difference in the mean frequency between the different activities, such as flying, resting, bathing and preening. There was a significant difference between the species activities and season and month. During the wet season, the highest mean frequency of activities was observed in April, while in the dry season the highest mean frequency of activities was observed in December. Although, the mean frequency of activities was slightly higher in the afternoon than morning, but it was not significant and does not determine the frequency of activities employed by the White-faced whistling duck. More research is needed to assess this species in early morning or late evening to achieve greatest accuracy and time-efficiency, creating desirable habitat in the vicinity by modifying the dam to encourage aquatic plant development.

Sequence Stratigraphy and Sedimentary Environment of Sarvak Formation, in the Oil Field of Kuhmond (Southwest of Iran)

Sarvak formation is one of the important hydrocarbon reservoirs in the Zagros Basin that is one of the mid-Cretaceous carbonate units in Bangestan group. This formation is located in the Kazhdomi Formation of the slope. Kuhmond oil field is in the southeast of Bushehr and in the north and northwestern of Fars province. In this study, sedimentology studies, stratigraphy and sedimentary environment in Sarvak Formation were studied. Based on studies, 18 main Microfacies were diagnosed in the region that have been deposited in four facies belts including open Sea, dam, lagoon and tidal zones. According to studies, the sedimentary environment of Sarvak formation in Kohmond field was diagnosed as a ramp carbonate platform (Figure 1).

Prevention and Mitigation of Debris Flow Hazards by Using Steel Open-Type Sabo Dams

This paper presents the findings of an investigation on the prevention and mitigation of debris flow hazards by using steel open-type dams. First, the actual cases of trapping hazardous debris flow by steel open-type dams were surveyed. Through a field survey of actual cases, we classified them into four distinct scenarios based on the trapping type of debris flow: Scenario A (wooden debris + rocks + sediment), Scenario B (wooden debris + sediment), Scenario C (rocks + sediment) and Scenario D (wooden debris only). Second, recent trapping cases on protection and mitigation by various steel open dams were introduced. Third, trapping scenarios A, B, C and D were confirmed by performing physical model tests. Finally, a safety check of a steel open dam against a large rock was verified by two impact analyses, the finite element method (FEM) impact analysis using ANSYS Autodyn software, and the three dimensional (3-D) impact frame analysis.

Numerical simulation of the dynamics of sedimentary river beds with a stochastic Exner equation

At the scale of a river reach, the dynamics of the river bed is typically modelled by Exner equation (conservation of the solid mass) with an empirical solid flux of transported sediments, which is a simple deterministic algebraic formula function of i) the sediment physical characteristics (size and mass) and of ii) the averaged hydrodynamical description of the ambient water flow. This model has proved useful, in particular through numerical simulations, for hydraulic engineering purposes (like estimating the mass of sediments that is drained through an open dam). Though, the model is also coarse. And its applicability at various space and time scales remains a question of considerable interest for sedimentologists. In particular, physical experiments from the grain scale to the laboratory scale reveal important fluctuations of the solid flux in given hydrodynamical conditions. This work is a preliminary study of the coupling of a stochastic Exner equation with a hydrody-namical model for large scales. (Stochastic models with a probabilistic solid flux are currently being investigated, but most often only from the viewpoint of theoretical physics at the grain scale.) We introduce a new stochastic Exner model and discuss it using numerical simulations in an appropriate test case.

A new water–sediment separation structure for debris flow defense and its model test

Structural measures, such as the commonly used open dam with a water-sediment separation function, are important in the mitigation of debris flow hazards and disasters. However, the existing open dams often lose their water-sediment separation function over time and/or during a debris flow event because of blockage by sediment and other debris. To resolve this problem, this paper describes a new debris flow water-sediment separation structure. This structure causes the separated sediment to leave the structure automatically and move to a deposit field. In this way, it maintains its water-sediment separation function in a debris flow event. To test the effectiveness of the new structure, model experiments were developed and tested in the laboratory. These showed that the water-sediment separation function was maintained. More than 80 % of the sediment larger than the design sediment was separated, and most of it left the structure automatically with the water-sediment separation functioning throughout the debris flow process.

A 400-year record of environmental change in an euxinic fjord as revealed by the sedimentary biomarker record

A 400-year sedimentary record of the euxinic Kyllaren Fjord was investigated using organic biogeochemical, geochemical and sedimentological approaches. Accumulation rates of a suite of biomarkers, and in some cases their stable carbon isotopic composition, were determined. Biomarkers were separated into three different groups: terrestrial derived, general aquatic/marine derived, and aquatic/marine derived but related to high primary productivity. Variations in bulk sediment parameters and biomarker accumulation rates with depth were used to interpret the sedimentary record. We infer that in the first half of the 19th century an environmental change occurred, caused by a change in either the precipitation regime, vegetation and/or land use. The data also show that in the last century, and especially in the last decades, a distinct increase in primary productivity occurred. Most likely this is caused by a ‘natural’ eutrophication due to the transformation of the fjord from an open to a confined system by the building of a partially open dam in 1954, possibly combined with anthropogenic eutrophication. A concurrent shoaling of the fjord chemocline may have had a mediating effect in the change towards a higher productivity by enhancing nutrient and carbon recycling. Enhanced carbon recycling is reflected by decreased δ 13C values of several biomarkers.