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Provider: - Institution: - Data provided by Europeana Collections- München, Bayerische Staatsbibliothek -- 4 Diss. 1748#Beibd.56- All metadata published by Europeana are available free of restriction ...under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
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Provider: - Institution: - Data provided by Europeana Collections- München, Bayerische Staatsbibliothek -- 4 Diss. 1745#Beibd.10- All metadata published by Europeana are available free of restriction ...under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
•A novel deep learning-based evolutionary model proposed for wind speed forecasting.•A new evolutionary hierarchy-based decomposition method introduced.•A developed evolutionary algorithm proposed in ...order to hyper-parameter tuning.•Generalised normal distribution algorithm is improved by an adaptive local search.•The proposed hybrid model improves the accuracy of short-term wind speed.
Due to expanding global environmental issues and growing energy demand, wind power technologies have been studied extensively. Accurate and robust short-term wind speed forecasting is crucial for large-scale integration of wind power generation into the power grid. However, the seasonal and stochastic characteristics of wind speed make forecasting a challenging task. This study adopts a novel hybrid deep learning-based evolutionary approach in an attempt to improve the accuracy of wind speed prediction. This hybrid model consists of a bidirectional long short-term memory neural network, an effective hierarchical evolutionary decomposition technique and an improved generalised normal distribution optimisation algorithm for hyper-parameter tuning. The proposed hybrid approach was trained and tested on data gathered from an offshore wind turbine installed in a Swedish wind farm located in the Baltic Sea with two forecasting horizons: ten-minutes ahead and one-hour ahead. The experimental results indicated that the new approach is superior to six other applied machine learning models and a further seven hybrid models, as measured by seven performance criteria.
In this paper, an extended optimal power-flow (OPF) model incorporating a detailed model of a voltage-source converter-based-multiterminal high-voltage direct current system (VSC-MTDC) is proposed, ...hereafter referred to as the mixed ac/dc OPF (M-OPF) model. A cost-benefit analysis approach using the M-OPF model as the calculation engine is proposed to determine the preferred VSC-MTDC alternative to be installed in an existing ac transmission system. In this approach, the operational benefits of VSC-MTDC systems are evaluated against their investment costs to derive the benefit-to-cost ratios (BCR) which reflect the cost-effectiveness of the alternatives. A case study has been carried out using a modified Nordic 32-bus system. The results of the study show that VSC-MTDC systems might lead to a reduction in total operation cost, and the reduction of the total system transmission loss depends to a large extent on the VSC-MTDC configuration. The results from sensitivity analyses show that if the VSC loss could be reduced to a third of the original level, the total benefit from the system would be increased by about 70%. A suggestion for the placement and configuration of a VSC-MTDC system is made based on calculated BCRs.
In a power system with high renewable power penetration, uncertain and intermittent characteristics of renewable energy resources become major concerns of system planning and operation. In such a ...power system, conventional thermal or hydro units have to be dispatched, shut down or started up more frequently to incorporate load, renewable resource variation and system failures. Slow ramp up (or down) of conventional units may cause energy shortage (or surplus) in power systems with high wind power penetration or in isolated micro grids with limited dispatchable capacity. This paper proposes a technique to evaluate operational reliability and energy utilization efficiency of power systems with high wind power penetration. The ramp rate of a conventional generator and energy storage system (ESS) are considered in the proposed technique. The effect of slow ramp-up rate or fast reduction of wind speed on system reliability is measured by the expected energy not supplied. A new index designated as the expected energy not used is proposed and formulated to represent energy surplus due to fast increase of wind speed and slow ramp down of conventional units. The IEEE-RTS is used to illustrate the applications of the proposed method.
A remarkable diversity of bioerosion trace fossils is reflected by the plethora of ichnotaxa that has been proposed for these structures during the past two centuries. Bioerosion traces include ...microborings, macroborings, grazing traces, attachment etchings, and predation traces. They occur in calcareous, siliceous, osteic, and xylic substrates, and are known or interpreted to be produced by tracemakers as diverse as bacteria, fungi, algae, invertebrates, and vertebrates. This review presents the status quo of an inventory of all bioerosion ichnotaxa currently recognized as valid, comprising 123 ichnogenera and 339 ichnospecies, including 45
combinationes novae
, the majority of which on account of fossil sponge bioerosion traces formerly grouped within the sponge biotaxon
Cliona
. In addition, the spelling of several ichnotaxa has to be corrected, leading to eight
nomina corrigenda
, and three cases of primary or secondary homonymy require establishing
nomina nova,
i.e., the new ichnogenus name
Irhopalia
replacing
Rhopalia
Radtke,
1991
, as well as the new ichnospecies names
Entobia morrisi
replacing
E. glomerata
(Morris,
1851
) and
Entobia tuberculata
replacing
E. mammillata
Bromley and D’Alessandro,
1984
, respectively. Ichnotaxa of dubious or invalid nomenclatural status currently include an additional 76 ichnogenera and 157 ichnospecies. The invalid ichnogenus
Ipites
is herein reinstated as new ichnogenus. Considering that only four valid (and one invalid) ichnofamilies had previously been established for bioerosion ichnotaxa, we here introduce a suite of 14 additional ichnofamilies: G
astrochaenolitidae
, T
alpinidae
, E
ntobiaidae
, P
lanobulidae
, I
chnoreticulinidae
, S
accomorphidae
, C
entrichnidae
, R
enichnidae
, P
odichnidae
, G
nathichnidae
, C
ircolitidae
, O
ichnidae
, B
elichnidae
, and M
achichnidae
. During the past five decades, the number of valid bioerosion ichnotaxa has more than quadrupled, reflecting a boost in bioerosion research, but also indicating the need for ichnotaxonomic consolidation in concert with a revision of key ichnogenera. In this context, the aim of this overview is to call for feedback from the research community in order to foster completeness of this list and to provide ichnotaxonomic stability. Furthermore, we want to raise awareness of the existence of the listed ichnotaxa, many of which obviously have remained unconsidered or forgotten for a long time.
Maintenance of offshore wind power plants is known to be extensive and costly. This paper presents a model for optimizing the maintenance support organization of an offshore wind farm: the location ...of maintenance accommodation, the number of technicians, the choice of transfer vessels, and the use of a helicopter. The model includes an analysis of a transportation strategy using alternative transportation means, a queuing model of maintenance activities, and an economic model of the maintenance support organization. An example based on a generic 100 wind turbine 5-MW wind farm is used to demonstrate the application of the model. The results show the benefit of the production losses of the different options, which enables the identification of an optimal maintenance support organization based on the reliability, logistic costs, and electricity price. The most cost-efficient maintenance support organization in the case study consists of an offshore accommodation with technicians on service 24 hours a day, 7 days a week. The solution suggests transportation by use of a crew transfer vessel equipped with a motion compensated access system.
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