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This research employs Gaussian Process Regression (GPR) with an ensemble kernel, integrating Exponential Squared, Revised Mat\'ern, and Rational Quadratic kernels to analyze pharmaceutical sales data. Bayesian optimization was used to identify optimal kernel weights: 0.76 for Exponential Squared, 0.21 for Revised Mat\'ern, and 0.13 for Rational Quadratic. The ensemble kernel demonstrated superior performance in predictive accuracy, achieving an \( R^2 \) score near 1.0, and significantly lower values in Mean Squared Error (MSE), Mean Absolute Error (MAE), and Root Mean Squared Error (RMSE). These findings highlight the efficacy of ensemble kernels in GPR for predictive analytics in complex pharmaceutical sales datasets., Comment: 6 pages, 5 figures

Arbitrage is one important revenue source for energy storage in electricity markets. However, a large amount of storage in the market will impact the energy price and reduce potential revenues. This can lead to strategic behaviors of profit-seeking storage investors. To study the investors' strategic storage investments, we formulate a non-cooperative game between competing investors. Each investor decides the storage investment over a long investment horizon, and operates the storage for arbitrage revenues in the daily electricity market. Different investors can deploy storage with different characteristics. Their decisions are coupled due to the market price that is determined by all the investors' decisions. We use market data from California ISO to characterize the storage impact on the market price, based on which we establish a centralized optimization problem to compute the market equilibrium. We show that an increasing number of investors will increase the market competition, which reduces investors' profits but increases the total invested storage capacity. Furthermore, we find that a slight increase in the storage efficiency (e.g., increased charge and discharge efficiency) can significantly improve an investor's profit share in the market.

This paper presents a novel algorithm to optimize energy capacity restoration of vanadium redox flow batteries (VRFBs). VRFB technologies can have their lives prolonged through a partially restoration of the lost capacity by electrolyte rebalancing. Our algorithm finds the optimal number and time of these rebalancing services to minimize the service cost, while maximizing the revenues from energy arbitrage. We show that the linearized form of this problem can be analytically solved, and that the objective function is convex. To solve the complete problem, we develop a two-step mixed integer linear programming (MILP) algorithm, which first finds the bounds for optimal number of services and then optimizes the number, and time of the services. We then present a theoretical analysis and optimization results for a case study of energy arbitrage in New York ISO., Comment: 3 pages, keywords: Flow batteries, degradation, cycle aging, capacity restoration, mixed integer linear programming

This paper introduces a mathematical formulation of energy storage systems into a generation capacity expansion framework to evaluate the role of energy storage in the decarbonization of distributed power systems. The modeling framework accounts for dynamic charging/discharging efficiencies and maximum cycling powers as well as cycle and calendar degradation of a Li-ion battery system. Results from a small-scale distributed power system indicate that incorporating the dynamic efficiencies and cycling powers of batteries in the generation planning problem does not significantly change the optimal generation portfolio, while adding substantial computational burden. In contrast, accounting for battery degradation leads to substantially different generation expansion outcomes, especially in deep decarbonization scenarios with larger energy storage capacities. Under the assumptions used in this study, it is found that battery energy storage is economically viable for 2020 only under strict carbon emission constraints. In contrast, given the projected technology advances and corresponding cost reductions, battery energy storage exhibits an attractive option to enable deep decarbonization in 2050., Comment: Energy 238 (2022): 121668

Revenue potential from offshore wind and energy storage systems for a Long Island node in the New York ISO (NYISO) is examined using advanced lithium-ion battery representations. These advanced mixed-integer-linear battery models account for the dynamic performance, as well as the degradation behavior of the batteries, which are usually not accounted for in power systems models. Multiple hybrid offshore wind and battery system designs are investigated to examine the impact of locating the battery offshore versus locating it onshore. For the examined systems, we explore different battery usable state-of-charge (SOC) windows, and corresponding dispatch of the battery to maximize energy- and capacity-market revenues. The impacts of variability of offshore wind output along with energy- and capacity-market prices are evaluated using publicly available data from 2010 to 2013. Locating the battery onshore resulted in higher revenues. For 2013, results highlight that without accurate battery representations, models can overestimate battery revenues by up to 155%, resulting primarily from degradation-related costs. Using advanced algorithms, net revenue can be increased by 29%. Results also indicate that wider useable SOC windows could lead to higher net revenues from the energy market, due to higher arbitrage opportunities that compensate for any additional degradation-tied costs in higher DODs. The added value of a MWh of energy storage varies from $2 to $3.5 per MWh of wind energy, which leads to a breakeven cost range of $50-$95 per kWh for the battery systems studied. As such, energy- and capacity-market revenues were found to be insufficient in recovering the investment costs of current battery systems for the applications considered in this analysis., Comment: 13pages

Decarbonization of the electricity sector is one of the major measures in slowing down the pace of climate change. In this paper, we analyze the impacts of energy storage systems (ESS) and interannual uncertainty of variable renewable energy (VRE) on power system decarbonization in 2050. We perform capacity expansion optimization based on technology cost projections and CO2 emission restrictions using 11 years of VRE and load data in Italy's power system, with a particular focus on the role of ESS and its duration. We also explore capacity expansion optimization based on multiple-year vs. single-year data to quantify the impact of VRE interannual variability. Our results indicate high renewables penetration even in the absence of decarbonization policies. In the transition to zero carbon system, CCS plays a minor role due to its carbon capture efficiency. ESS investments contribute to lower system costs by replacing more expensive flexibility resources. However, longer ESS durations have lower marginal value per added kWh ESS. Interannual variability of VRE substantially changes the system's configuration and energy cost. Decision-making based on single-year data substantially increases the systems' operational costs in other years. In contrast, optimizing over multiple years provides a more robust and cost effective generation expansion strategy., Comment: 12 pages, 10 figures

This paper proposes a hierarchical Bayesian model for probabilistic estimation of the electric vehicle battery capacity fade. Since the battery aging factors such as temperature, current, and state of charge are not fixed, and they change in different times, locations and by the different users, deterministic models with constant parameters cannot accurately evaluate the battery capacity fade. Therefore, a probabilistic presentation of the capacity fade including uncertainties of the measurements or observations of the variables can be a proper solution. We have developed a hierarchical Bayesian Network model for the electric vehicle battery capacity fade considering multiple external variables. The mathematical expression of the model is extracted based on Bayes theorem, the probability distributions for all variables and their dependencies are carefully chosen where the Metropolis Hastings Markov Chain Monte Carlo sampling method is applied to generate the posterior distributions. The model is trained with 85 percent of experimental data to obtain its unseen parameters and tested with other 15 percent of data to prove its accuracy. Also, three case studies for different drivers, different grid services frequencies, and different climates are explored to show model flexibility with different input data. The developed model needs training data for parameter tuning in different conditions. However, after training, it has more than 95 percent precision in estimating the battery capacity fade percentage., Comment: 12 pages, 21 figures

An assumption in micromechanical analysis of polymers is that the constitutive polymeric media is non-porous. Non-porosity of media, however, is merely a simplifying assumption. In this paper, we neglect this assumption and studied polymer networks with a different porosity volume fraction. A random morphology description function is used to model the porosity of the network and nonlinear finite element analyses are conducted to perform structural analysis of porous polymer networks. The results show that the porosity effect is significant in mechanical behavior of polymer networks and may increase the maximum Von-Mises stress drastically.

This paper shows the CFD investigation of pressure drop and thermal performance of aluminum oxide nano fluid inside square channel inserted a cylinder with and without fin using two-phase method. The constant heat flux on outer wall and laminar flow regime are applied in the considered domain using finite volume method. The results depict that the enhance of nano-particles volume concentration and Reynolds number have dramatic effects on heat transfer coefficient enhancement. Moreover, the increase of nano-particle diameter has opposite impact on heat transfer efficiency. The passive way leads to higher pressure drops. For all fluids under consideration, pressure drop escalated with Reynolds number. Injecting nano-particles into the water causes to increase in pressure drop and this impact is more significant in high nano-particle volume fraction., Comment: 31 pages, 15 figures, submitted to Applied Energy

This paper is devoted to obtain the one-dimensional group invariant solutions of the two-dimensional Ricci flow ((2D) Rf) equation. By classifying the orbits of the adjoint representation of the symmetry group on its Lie algebra, the optimal system of one-dimensional subalgebras of the ((2D) Rf) equation is obtained. For each class, we will find the reduced equation by the method of similarity reduction. By solving these reduced equations, we will obtain new sets of group invariant solutions for the ((2D) Rf) equation., Comment: 6 pages

In this paper, partially invariant solutions (PISs) method is applied in order to obtain new four-dimensional Einstein Walker manifolds. This method is based on subgroup classification for the symmetry group of partial differential equations (PDEs) and can be regarded as the generalization of the similarity reduction method. For this purpose, those cases of PISs which have the defect structure delta=1 and are resulted from two-dimensional subalgebras are considered in the present paper. Also it is shown that the obtained PISs are distinct from the invariant solutions that obtained by similarity reduction method., Comment: 8 pages

Storage of natural gas in salt caverns had been developed mainly for seasonal storage, resulting in a small number of yearly pressure cycles and moderate gas-production rates. The needs of energy traders are changing towards more aggressive operational modes. The "high-frequency cycling" operation of salt caverns raises questions concerning the effects of frequently repeated and intense mechanical and thermal loading. These questions concern the constitutive creep laws for salt, laboratory test procedures, criteria to be used at the design stage to provide operability, and the long-term integrity of the underground salt caverns., Comment: in French, JNGG 2012, Bordeaux : France (2012)