•A single energy storage can always be split into two hybrid energy storages.•These hybrid storages have the same total energy and power as the single storage.•The potential for storage hybridisation ...depends on the shape of the power profile.•A higher potential allows a higher spread of the power/energy-ratios of the storages.•Automobile and pulsed power applications are well suited for storage hybridisation.
Aim of a storage hybridisation is a beneficial usage or combination of different storage technologies with various characteristics to downsize the overall system, decrease the costs or to increase the lifetime, system efficiency or performance. In this paper, the point of interest is a different ratio of power to energy (specific power) of two storages to create a hybrid energy storage system (HESS) with a resulting specific power that better matches the requirements of the application. The approach enables a downsizing of the overall system compared to a single storage system and consequently decreases costs. The paper presents a theoretical and analytical benchmark calculation that determines the maximum achievable hybridisation, i.e. possible spread in specific power, while retaining the original total energy and power capacities of an equivalent single storage system. The theory is independent from technology, topology, control strategy, and application and provides a unified view on hybrid energy storage systems. It serves as a pre-dimensioning tool and first step within a larger design process. Furthermore, it presents a general approach to choose storage combinations and to characterize the potential of an application for hybridisation. In this context, a Hybridisation Diagram is proposed and integral Hybridisation Parameters are introduced.
•PDF of wind, PV and load forecast errors can be modelled by an intermittency model.•Their standard deviations generated on 1 h and 15 min resolution correlate linearly.•Common dimensioning of FRR ...lead to significant reductions of FRR capacities.•FRR capacities will increase significantly until 2050 if not commonly dimensioned.
This paper advances the probabilistic modelling approach for dynamic dimensioning of Frequency Restoration Reserve (FRR) capacities of 1. The approach is based on the convolution of forecast error distributions of generation and load sources. The improvements include 1. the replacement of normal distributions with better fitting intermittency distributions to model forecast error distributions of wind and photovoltaic generation and load, 2. the adjustments for facilitating the dynamic and static dimensioning for 20 European load-frequency control (LFC) blocks, 3. the dimensioning of FRR capacities not only for a historical year (2016) but also for a scenario year 2050 with 100% renewable generation and 4. the implementation of a common dimensioning of several LFC blocks in order to determine the saving potential of an implied integration of European LFC blocks.
Among the recent advances and innovations in satellite communications, Non-Geostationary Orbit (NGSO) satellite constellations are gaining popularity as a viable option for providing widespread ...broadband internet access and backhauling services. However, a more complex ground segment with multiple ground stations is necessary due to these satellites' high speeds and low altitudes. The complete dimensioning of the ground segment, including gateway optimal placement and the number of ground access points, remains a relevant open challenge. In this article, we provide an overview of the key factors that shall be considered for NGSO gateway station geographical planning. Subsequently, we propose a ground segment dimensioning approach that combines several criteria, such as rain attenuation, elevation angle, visibility, geographical constraints, and user traffic demands. The operational concept is first discussed, followed by a methodology that combines all these constraints into a single map-grid to select the best position for each gateway. Furthermore, a case study is presented, which demonstrates the performance of the proposed methodology, for one example constellation. Finally, we highlight relevant open challenges and key research directions in this area.
Emerging 5G cellular networks are expected to face a dramatic increase in the volume of mobile traffic and IoT user requests due to the massive growth in mobile devices and the emergence of new ...compute-intensive applications. Running high-intensive compute applications on resource-constrained mobile devices has recently become a major concern, given the constraints of finite computation and limited storage capacities. Mobile Edge Computing (MEC) has recently become the key technology to overcome these issues by providing cloud computing capabilities and placing IT infrastructures at the mobile network edge. In this survey, we present a list of relevant research papers for the MEC infrastructure implementation phases, including (1) MEC infrastructure designing and dimensioning, (2) MEC infrastructure virtualization using Network Function Virtualization (NFV) concept, and the use of virtualized service placement and auto-scaling methods to deploy an agile system framework, (3) MEC resource management frameworks, and (4) approaches used to optimize the MEC resources on the physical infrastructure. The main focus of this survey is to determine the required aspects to implement an auto-scaled and proactive MEC-NFV infrastructure to support a dynamic and heterogenous mobile users' demand at mobile network operators.
•Investigates losses and efficiency enhancement opportunities in pumping system.•Presents efficient component selection in pumping system.•Suggests energy optimised sizing and dimensioning of piping ...system.•Reviews optimal control and adjustment methods in parallel pumping.•Highlights ongoing research and developments for improving pumping efficiency.
The energy consumption across the globe is increasing at an alarming rate. This has already shown its impact in the depletion of energy sources and environmental issues (global warming, and weakening of the ozone layer). Certainly, this escalating tendency of energy insufficiency will get aggravated in the future. Efficiency enhancement initiatives are considered to be the key solution in reducing the energy utilization and eventually resisting the global environmental impacts. Of the world’s total energy generated, pumping systems, especially the centrifugal pumps consume about 20%. Consequently, the primary focus of global energy policy makers is to enhance energy efficiency in pumping systems. As per the literature, remarkable energy savings can be accomplished by controlling the speed of the pumping system using Variable Frequency Drives (VFDs). For this reason, studies and researches focus primarily on VFD control techniques to improve the efficiency of the pumping system. This article also focuses on component selection, and system dimensioning in addition to the control techniques. Comparison of recent research outcomes of energy efficiency improvements in pumping system has been made to provide an insight for future research.
•Probabilistic simulation-based multi-objective optimization approach for hybrid power systems.•Study the uncertainties of renewable resources availability, load demand, and components ...failure.•Post-optimization sensitive analysis leads to unfeasible solutions.•Optimization with uncertainties implies higher costs for the same level of reliability.•Useful decision making tool to design optimum and robust power systems.
This paper proposes a probabilistic simulation-based multi-objective optimization approach for dimensioning robust renewable based Hybrid Power Systems. The method integrates an Optimization Module based on a multi-objective Genetic Algorithm, an Uncertainty Module that uses Latin Hypercube Sampling method and Monte Carlo Simulation to generate uncertainty scenarios and a Simulation Module to simulate the power system under real operating conditions. Uncertainties considered include the renewable resources availability, the load demand, and the probability of the components’ failure. The performance of the proposed approach was assessed in a rural community of the Amazonian region of Brazil. Results show that a system configuration with the same level of reliability as in the deterministic scenario implies a higher economic cost; however, the configurations obtained probabilistically represent feasible robust solutions and guarantee a reliable source of generation. The proposed optimization method constitutes a useful decision making tool for dimensioning hybrid power systems that require both optimality and robustness.
PurposeThe purposes of this study were (1) to explore empirical challenges in dimensioning safety buffers and their implications and (2) to organise those challenges into a ...framework.Design/methodology/approachIn a multiple-case study following an exploratory, qualitative and empirical approach, 20 semi-structured interviews were conducted in six cases. Representatives of all cases subsequently participated in an interactive workshop, after which a questionnaire was used to assess the impact and presence of each challenge. A cross-case analysis was performed to situate empirical findings within the literature.FindingsTen challenges were identified in four areas of dimensioning safety buffers: decision management, responsibilities, methods for dimensioning safety buffers and input data. All challenges had both direct and indirect negative implications for dimensioning safety buffers and were synthesised into a framework.Research limitations/implicationsThis study complements the literature on dimensioning safety buffers with qualitative insights into challenges in dimensioning safety buffers and implications in practice.Practical implicationsPractitioners can use the framework to understand and overcome challenges in dimensioning safety buffers and their negative implications.Originality/valueThis study responds to the scarcity of qualitative and empirical studies on dimensioning safety buffers and the absence of any overview of the challenges therein.
FEM analysis of the hatch for special use Fiačan, Jakub; Hrček, Slavomír; Jenis, Jozef ...
Transportation research procedia (Online),
2023, Letnik:
74
Journal Article
A coupled experimental and modelling approach was used to develop an adapted PHBV active film with Lauroyl Arginate Ethyl (LAE®) as an antimicrobial compound incorporated in the bulk or as a coating ...to prolong the shelf life of cheese. The minimum inhibitory concentration (MIC) of LAE® was evaluated in the range of 25–100 ppm against spoilage and pathogenic microorganisms, such as Micrococcus luteus, Penicillium roqueforti, Salmonella enteritidis, and Pseudomonas putida. Film production induced a loss of 50 % of LAE® when introduced into the bulk, whereas only 4 % was lost in the case of incorporation by coating. When in contact with food simulant D1 (50 % ethanol), a release of 43 % and 34 % of LAE® was achieved in 10 days at 20 °C for LAE® incorporated as a coating and in the bulk, respectively, while a lower release level of 34 % and 14 % respectively was observed in food simulant C (20 % ethanol), confirming the interest to use active coating for fatty foods. The developed packaging was well adapted to reach the MIC while remaining below the admissible daily intake. The results also showed that the PHBV film activated with LAE® incorporated as a coating was as effective as modified atmosphere packaging (MAP) to preserve cheese against microorganism growth.
•A LAE® antimicrobial packaging was dimensioned for cheese application.•MIC of LAE® was in the range of 25-100 ppm against various microorganisms and molds.•50 % and 4 % of LAE® was lost from bulk and coated PHBV during forming process.•14-34 and 34-43 % of LAE® diffused in food simulant C and D1 from bulk and coated PHBV.•LAE coated packaging was as effective as MAP for paste cheese application.
Modular multilevel converters (MMC) represent an interesting and emerging topology in medium-voltage motor drive applications. The main challenge of using such a topology in variable-speed drives is ...the large voltage ripple of submodule capacitors at low speed with constant torque. In this paper, an improved circulating current injection method is proposed, which does not completely eliminate the capacitor voltage ripple, but maintains it bounded within reasonable values. As a result, magnitude of injected circulating current is reduced, leading to converter efficiency improvement and reduction of semiconductor current ratings. Dimensioning of submodule capacitance is also discussed, which is an important consideration when designing the MMCs in variable-speed drives. The proposed method has been successfully validated by simulation and experimental results.
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