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The increasing aggregation of renewable‐based distributed generating units besides the impressive growing usage of non‐linear loads raises unwanted challenges for traditional power terms definition in power engineering. This fact consequently affected the performance of the conventional control frameworks and industrial compensation techniques. In this study, the authors aim to provide an insightful summary over the most recognised time domain‐based instantaneous power theories and discuss their advantages and disadvantages within a comprehensive mathematical‐conceptual and applicational framework for professionals who are using instantaneous power theories within the smart grid applications. They conclude that there is still a need for a modified power theory which can be validated under non‐sinusoidal‐unbalanced load/source conditions respecting the physical meaning of different power and current components.

Sustainability is increasingly becoming a core focus of geography, linking subfields such as urban, economic, and political ecology, yet strategies for achieving this goal remain illusive. Socio-technical transition theorists have made important contributions to our knowledge of the challenges and possibilities for achieving more sustainable societies, but this body of work generally lacks consideration of the influences of geography and power relations as forces shaping sustainability initiatives in practice. This paper assesses the significance for geographers interested in understanding the space, time, and scalar characteristics of sustainable development of one major strand of socio-technical transition theory, the multi-level perspective on socio-technical regime transitions. We describe the socio-technical transition approach, identify four major limitations facing it, show how insights from geographers – particularly political ecologists – can help address these challenges, and briefly examine a case study (GMO and food production) showing how a refined transition framework can improve our understanding of the social, political, and spatial dynamics that shape the prospects for more just and environmentally sustainable forms of development.

According to the characteristics of the microscopic unit strength of rock with random distribution, the power function distribution, and the Weibull distribution which is widely used in the past as the distribution function of the strength of the rock. Based on the theory of rock damage and statistical strength theory, two damage constitutive models established under three different confining pressures are modified. Then, the damage constitutive modified model of two kinds of distribution is verified and compared with the existing three axis test data. The results show that: (1) In the stage of elastic deformation of rock, the two theoretical damage constitutive model curves are in high agreement with the three axis test curve; (2) The rock at the plastic stage (hardening and softening), damage constitutive model established by Weibull probability distribution and experimental curve fits better than the damage constitutive model established by power function distribution. Especially in high confining pressure, damage constitutive model based on Weibull distribution can well describe the rock deformation from brittle to ductile transition process and power function is not; (3) In the residual strength in rock, damage variable D of damage constitutive model based on power function distribution appeared more than 1, which is deviation from the actual one and damage constitutive model based on Weibull distribution is not deviating. To summarize, using Weibull distribution statistical probability model to describe the microscopic unit strength of rock is more reasonable.

Distributed energy technologies are gaining popularity nowadays; however, due to the highly intermittent characteristics of distributed energy resources, a larger penetration of these resources into the distribution grid network becomes of major concern. The main issue is to cope with the intermittent nature of the renewable sources alongside the requirements for power quality and system stability. Unlike traditional power systems, the control and optimization of complex energy systems comprising of wind, solar, thermal, and energy storage becomes difficult in many aspects, such as modelling, integration, operation, coordination and planning etc. This means that energy conversion as per the standards imposed by the energy market is unachievable without adequate control, management, and optimization. This edited book serves as a resource for the engineers, scientists and professionals working on distributed energy systems. The book is an extensive collection of state-of-the-art studies on advanced control paradigms for complex energy systems, with emphasis on the optimization and management of the high penetration of distributed energy resources into power distribution networks. Readers will find the book inspiring and useful whilst carrying out their own research in distributed energy systems. Key features: • An extensive collection of state-of-the-art studies on advanced control paradigms for complex energy systems. • Emphasis on the optimization and management of high penetration of distributed energy resources into power/energy distribution networks. • Serves as a valuable resource for engineers, scientists, academicians, experienced professionals, and research scholars who are working in management of energy systems.

We derive exact traversable wormhole solutions in the framework of f ( R ) gravity with no exotic matter and with stable conditions over the geometric fluid entering the throat. For this purpose, we propose power-law f ( R ) models and two possible approaches for the shape function b ( r )/ r . The first approach makes use of an inverse power-law function, namely b ( r ) / r ∼ r - 1 - β . The second one adopts Padé approximants, used to characterize the shape function in a model-independent way. We single out the P (0, 1) approximant where the fluid perturbations are negligible within the throat, if the sound speed vanishes at r = r 0 . The former guarantees an overall stability of the geometrical fluid into the wormhole. Finally, we get suitable bounds over the parameters of the model for the above discussed cases. In conclusion, we find that small deviations from general relativity give stable solutions.

Are labels good or bad for consumers and firms? The answer may seem straightforward since labels improve information, yet economic theory reveals situations where their introduction reduces the welfare of at least some market participants. This essay reviews the theoretical literature on labels in order to identify and explain the main reasons that may cause labeling to produce undesirable side-effects. In contrast to earlier reviews that either concentrate on narrow topics or treat the subject in a more or less informal way, we bring together the main results from all the relevant topics by presenting and discussing the assumptions and model-building techniques that underpin them. The advantage of this approach is that it identifies the origin of the differences between results, thus allowing the synthesis of results that sometimes appear even to be contradictory. We focus on \"quality labels\" and examine the impact of labeling on market structure, the side-effects of costly certification, issues related to the label's trustworthiness, the rationale for mandatory vs. voluntary labeling, the level at which the label's standard is set according to the agency that selects it, the political economy of labels, that is, pro- or anti-label lobbying, lobbying to affect the label's standard, and lobbying in favor or against the label's mandatory imposition. These topics cover a wide range of applications, including Genetically Modified Organism (GMOs), organic produce, geographic indicators, controlled origin, eco-labels, etc. We conclude by identifying topics that require further research.

The problem of testing the equality of coefficients of variation of independent normal populations is considered. For comparing two coefficients, we consider the signed-likelihood ratio test (SLRT) and propose a modified version of the SLRT, and a generalized test. Monte Carlo studies on the type I error rates of the tests indicate that the modified SLRT and the generalized test work satisfactorily even for very small samples, and they are comparable in terms of power. Generalized confidence intervals for the ratio of (or difference between) two coefficients of variation are also developed. A modified LRT for testing the equality of several coefficients of variation is also proposed and compared with an asymptotic test and a simulation-based small sample test. The proposed modified LRTs seem to be very satisfactory even for samples of size three. The methods are illustrated using two examples.

In this paper, the concept of fractional calculus (FC) is introduced into the sliding mode control (SMC), named fractional order SMC (FOSMC), for the load frequency control (LFC) of an islanded microgrid (MG). The studied MG is constructed from different autonomous generation components such as diesel engines, renewable sources, and storage devices, which are optimally planned to benefit customers. The coefficients embedded in the FOSMC structure play a vital role in the quality of controller commands, so there is a need for a powerful heuristic methodology in the LFC study to adjust the design coefficients in such a way that better transient output may be achieved for resistance to renewable sources fluctuations. Accordingly, the Sine Cosine algorithm (SCA) is effectively combined with the harmony search (HS) for the optimal setting of the controller coefficients. The Lyapunov function based on the FOSMC is formulated to guarantee the stability of the LFC mechanism for the test MG. Finally, the hardware-in-the-loop (HIL) experiments are carried out to ensure that the suggested controller can suppress the frequency fluctuations effectively, and that it provides more robust MG responses in comparison with the prior art techniques.

This article introduces a nonparametric approach to multivariate time-varying power spectrum analysis. The procedure adaptively partitions a time series into an unknown number of approximately stationary segments, where some spectral components may remain unchanged across segments, allowing components to evolve differently over time. Local spectra within segments are fit through Whittle likelihood-based penalized spline models of modified Cholesky components, which provide flexible nonparametric estimates that preserve positive definite structures of spectral matrices. The approach is formulated in a Bayesian framework, in which the number and location of partitions are random, and relies on reversible jump Markov chain and Hamiltonian Monte Carlo methods that can adapt to the unknown number of segments and parameters. By averaging over the distribution of partitions, the approach can approximate both abrupt and slowly varying changes in spectral matrices. Empirical performance is evaluated in simulation studies and illustrated through analyses of electroencephalography during sleep and of the El Niño-Southern Oscillation. Supplementary materials for this article are available online.

Energy sharing through a microgrid (MG) is essential for islanded communities to maximise the use of distributed energy resources (DERs) and battery energy storage systems (BESSs). Proper energy management and control strategies of such MGs can offer revenue to prosumers (active consumers with DERs) by routing excess energy to their neighbours and maintaining grid constraints at the same time. This paper proposes an advanced power‐routing framework for a solar‐photovoltaic (PV)‐based islanded MG with a central storage system (CSS). An optimisation‐based economic operation for the MG is developed that determines the power routing and energy sharing in the MG in the day‐ahead stage. A modified droop controller‐based real‐time control strategy has been established that maintains the voltage constraints of the MG. The proposed power‐routing framework is verified via a case study for a typical islanded MG. The outcome of the optimal economic operation and a controller verification of the proposed framework are presented to demonstrate the effectiveness of the proposed power‐routing framework. Results reveal that the proposed framework performs a stable control operation and provides a profit of 57 AU$/day at optimal conditions.