Next-Day Peak Electricity Price Forecasting Using NN Based on Rough Sets Theory

Electricity price forecasting is an essential task for market participants in deregulated electricity market. This paper proposes an approach for next-day peak electricity price forecasting, since it is important for risk management and bidding strategy. In the proposed method, neural network (NN) is employed as the forecasting method, and its learning data is selected by using rough sets. Moreover, the creating method of learning data based on temperature fluctuation is also proposed for generation of new learning data in order to efficiently learn. This method is examined by using the data of Pennsylvania-New Jersey-Maryland (PJM) electricity market and The independent electricity system operator (IESO) market. From the simulation results, it is observed that the proposed method is useful for next-day peak electricity price forecasting. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Adaptive notch filter for synchronization and islanding detection using negative‐sequence impedance measurement

Dispersed generation (DG) has been found promising for satisfying the requirements of high power quality in distributed systems. One operation situation, namely, an island, is formed when one or more DG systems and an aggregate of local loads are disconnected from the main grid and remain operational as an islanded entity. Islanding is either due to intentional events, e.g. maintenance outage, or due to unintentional events, such as faults, and their subsequent switching actions. Islanding is usually undesirable because of the potential harm it causes to the existing equipment, human safety, power reliability and quality, etc. Accordingly, anti‐islanding schemes are used to immediately detach a DG system from the feeder after islanding. This paper presents an active method of detecting islanding for DG systems by injecting a small negative voltage into the point of common coupling, and then measuring the negative system impedance. In this study, an adaptive notch filter is introduced as a synchronous part instead of a phase‐locked loop and as a signal processing unit as well. The proposed control strategy allows DG systems to detect properly the occurrence of islanding in a balanced distribution system. Simulation results show the overall system performance including synchronization, power control, and islanding detection capability of the simulated DG system. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Analysis of inner structure in high-strength biodegradable fibers by X-ray microtomography using synchrotron radiation

The observation of the inner structure of materials without pretreatment or damage is a very useful analytical method in the field of materials science as well as in medicine and biology. We have carried out a three-dimensional (3D) analysis of biodegradable polyester bacterial-poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyvalerate] (P(3HB-co-3HV)) fibers with high tensile strength (1.07 GPa) using X-ray microtomography with synchrotron radiation. The inner structure of the fibers was visualized at a spatial resolution of 1 μm. There are many fine voids for one-step-drawn P(3HB-co-3HV) fibers after isothermal crystallization from the result of X-ray microtomography. This revealed that the clear streak reflection along the equator in small-angle X-ray scattering is caused by these fine voids. The recalculated tensile strength of one-step-drawn P(3HB-co-3HV) fibers after isothermal crystallization is suggested to be 2.02 GPa, taking the cross-section area with 52.7% (polymer region) into consideration. These fine voids in fibers seemed to be generated by the volume changes due to the contraction of polymer chains during isothermal crystallization.     

MAPKs and Signal Transduction in the Control of Gastrointestinal Epithelial Cell Proliferation and Differentiation

Mitogen-activated protein kinase (MAPK) pathways are activated by several stimuli and transduce the signal inside cells, generating diverse responses including cell proliferation, differentiation, migration and apoptosis. Each MAPK cascade comprises a series of molecules, and regulation takes place at different levels. They communicate with each other and with additional pathways, creating a signaling network that is important for cell fate determination. In this review, we focus on ERK, JNK, p38 and ERK5, the major MAPKs, and their interactions with PI3K-Akt, TGFβ/Smad and Wnt/β-catenin pathways. More importantly, we describe how MAPKs regulate cell proliferation and differentiation in the rapidly renewing epithelia that lines the gastrointestinal tract and, finally, we highlight the recent findings on nutritional aspects that affect MAPK transduction cascades.