Business decision-making of power generators in competitive electricity market.

This paper presents a theoretical framework for the business decision-making process of the power generators as price takers when considering the participation of energy storage. The framework assesses rational valuation, optimal sales strategies, and hedging options for power plants with and without a gross sales constraint. The valuation and optimal sales strategy problems are analyzed using a risk-neutral pricing approach, dynamic programming principles, and the trinomial tree model suitable for the regime switching model. The formulation of a price risk hedging scheme flexible and widely used over-the-counter electricity derivative, the electricity contract for difference, as a tool for hedging electricity spot price risk. The minimum variance hedge ratio and its corresponding hedging efficiency formula are derived. In the section of numerical simulations, we first use the EM algorithm to calibrate the electricity spot model based on electricity spot price data of Nord Pool. Numerical simulations are then conducted on the operational decision-making of power generators under three different forms of energy storage. The results of the simulations provide a basis for power generators to evaluate the real-time value of power plants, to select optimal real-time power sales, and to determine the optimal timing of power plant transfer and storage methods.

Factors affecting hemostasis in the control of iatrogenic renal hemorrhage.

PURPOSE: To investigate factors affecting hemostasis in iatrogenic renal hemorrhage. METHODS: Seventy-three patients with iatrogenic renal hemorrhage experiencing selective renal artery angiography between Jan 2015 and Dec 2020 were enrolled in this study. The clinical features, treatment modalities and outcomes were reviewed. Factors affecting hemostasis were analyzed by univariate and multivariate models using linear regression techniques. The optimum values of the independent factors to predict postangiographic hemostasis were conducted by receiver operating characteristic (ROC) curve analysis. RESULTS: Of the 73 iatrogenic renal hemorrhage patients, 47 (64.4%) patients had positive angiographic findings and received therapeutic embolization. Of the patients with negative angiographic findings, 20 (76.9%) and 6 (23.1%) received conservative therapy and prophylactic embolization, respectively. The red blood cell (RBC) count (OR = 0.61, P = 0.04), the hematuria time before angiography (OR = - 0.19, P < 0.01) and treatment modality were independent factors affecting hemostasis time. The ROC curve analysis showed that the RBC count of 3.5 × 109/L and the hematuria time before angiography of 7 days were the optimum indicators. Therapeutic embolization and prophylactic embolization were protective factors affecting hemostasis time compared with conservative treatment (OR = - 1.59, P = 0.02; OR = - 3.31, P < 0.01). CONCLUSIONS: The hematuria time before selective renal artery angiography, the RBC count, and embolization treatment are associated with rapid hemostasis. Embolization is an effective strategy for iatrogenic renal hemorrhage, and also enables rapid hemostasis in patients with negative angiographic findings.

The viscosity solutions approach to swing options pricing under a regime-switching mean-reverting model.

In this paper, we study the valuation of swing options on electricity markets with local volume and refraction time constraints, under the setting that the dynamic of the underlying spot price is a 2-state regime-switching mean-reverting process. We derive the corresponding optimal multiple stopping problem, reduce it to a sequence of optimal single stopping problems, and further find that those value functions satisfy HJB variational inequalities subject to suitable conditions. Then after a prior estimation for the value functions, the viscosity solutions approach is adopted to get existence and uniqueness results in viscosity sense.