Economic Evaluation of Power System Flexibility by Commercial Air Conditioner Control with Large Penetration of Photovoltaic Generation

High penetration of intermittent renewable energy such as photovoltaic (PV) and wind power could cause shortage of power system flexibility. Demand response is expected to help supply ancillary service instead of the conventional power plant. Commercial air conditioners are a promising responsive load for demand response because they account for a large proportion of power consumption in the power system. We calculate a system operation cost and hourly operation pattern of each power plant by using the optimal power generation model considering flexibility supply from controlling commercial air conditioner. We obtained the following results as an effect of commercial air conditioner control. (1) The power generation of oil fired power plants decreases at peak time and annual fuel cost of oil fired plant is reduced by approximately 30% at most in Kanto area. (2) The percentage of rated operation mode of LNG combined cycle plants increases. (3) Curtailed energy rate of PV decreases because a power storage amount by pumped hydropower generation increases. (4) Required battery capacity to reduce PV curtailed amount decreased by combining battery energy storage system in case of high penetration of PV.     

The Effects of Geometric Uncertainties on Micro-Channel Heat Transfer—A CFD Study on the Tilted-Cover Problem

The present paper attempts to shed light on issues that so far have been unaddressed in research on micro-channel heat transfer. The first part of the paper summarizes the uncertainty sources likely to be present in micro-channel cooling devices incorporated in the electronic package. The effects of uncertainties on the heat transfer performance of the cooling device are difficult to assess due to the coupling of diverse factors in a narrow physical space. The CFD simulation offers a means to sort out the effects from multiple factors by assuming uncertainties from one of the sources or a set of selected sources into an analytical model.

A model channel is defined to illustrate the application of the CFD-based methodology to situations involving geometric uncertainties. The model has a 20 mm × 20 mm heater plate set in a channel having an adiabatic cover and side-walls and cooled by a dielectric coolant. The tilt of the cover plate is chosen as an uncertainty factor from among all possible factors. CFD simulations were performed for the cases where the nominal channel height was changed from 1 mm to 0.1 mm with a proportionate reduction of the cover tilt from 1° to 0.1°. The results indicate a measure of required stringency in assembling the micro-channel cooling device. Also, a hypothetical experiment is considered where the performance of a channel having an optimum height is compared with that of a non-optimum channel under a given pumping power. Examination of the simulation results revealed that the cover tilts in both channels could blur or amplify the optimality of the channel height to an appreciable extent.     

Development of Magnetic Levitation System for Science and Technology Education: Magnetic Levitation Control by Using a Hall Element Displacement Sensor with Neural Network

In this study, we developed a magnetic levitation system using a Hall element displacement sensor with neural network for science and technology education. The sensor configured with three Hall elements was devised in order to measure displacement from an electromagnet to a levitated object with a permanent magnet. Use of the Hall element displacement sensor achieves a lower cost magnetic levitation system. Furthermore, three‐layered feedforward neural network was utilized in order to improve the precision of the Hall element displacement sensor. Finally, operation verification of the developed magnetic levitation system was conducted by designing state feedback regulator with observer.     

A method for estimating spatial resolution of real image in the Fourier domain

Spatial resolution is a fundamental parameter in structural sciences. In crystallography, the resolution is determined from the detection limit of high‐angle diffraction in reciprocal space. In electron microscopy, correlation in the Fourier domain is used for estimating the resolution. In this paper, we report a method for estimating the spatial resolution of real images from a logarithmic intensity plot in the Fourier domain. The logarithmic intensity plots of test images indicated that the full width at half maximum of a Gaussian point spread function can be estimated from the images. The spatial resolution of imaging X‐ray microtomography using Fresnel zone‐plate optics was also estimated with this method. A cross section of a test object visualized with the imaging microtomography indicated that square‐wave patterns up to 120‐nm pitch were resolved. The logarithmic intensity plot was calculated from a tomographic cross section of brain tissue. The full width at half maximum of the point spread function estimated from the plot coincided with the resolution determined from the test object. These results indicated that the logarithmic intensity plot in the Fourier domain provides an alternative measure of the spatial resolution without explicitly defining a noise criterion.