A simple instant‐estimation method for time‐average quantities of single‐phase power and application to single‐phase power grid connection by inverter

This paper presents and analyzes a new simple instant‐estimation method for time‐average quantities such as rms values of voltage and current, active and reactive powers, and power factor for single‐phase power with the fundamental component of constant or nearly constant frequency by measuring instantaneous values of voltage and current. According to the analyses, the method can instantly estimate time‐average values with accuracy of the fundamental frequency, and estimation accuracy of the power factor is about two times better than that of voltage, current, and powers. The instant‐estimation method is simple and can be easily applied to single‐phase power control systems that are expected to control instantly and continuously power factor on a single‐phase grid by inverter. Based on the proposed instant‐estimation method, two methods for such power control systems are also proposed and their usefulness is verified through simulations. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(2): 34–43, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20236     

Synthesis of novel hydride Li3AlFeH8 at high temperature and pressure

Iron-containing complex hydrides are a fascinating class of materials for hydrogen storage applications because they consist of abundant iron and usually contains [FeH₆]^4? complexes, resulting in high hydrogen densities. In this study, we synthesized theoretically predicted Li₃AlFeH₈, which has the highest gravimetric hydrogen density of all transition metal complex hydrides, through a hydrogenation reaction of LiH, AlH₃, and pure iron powder mixture under high pressure. The reaction process was observed in situ using a synchrotron radiation x-ray diffraction technique to clarify its reaction kinetics. The reaction temperature and pressure were changed to optimize reaction conditions for obtaining single phase Li₃AlFeH₈. Unfortunately, we did not obtain single phase Li₃AlFeH₈ because the reaction was slow. In addition, there were other phases with similar thermodynamic stabilities to that of Li₃AlFeH₈. Another novel hydride, LiAlFeH₆, was found to be synthesized above 850 °C at 9 GPa.     

Phase‐Responsive Fourier Nanotransducers for Probing 2D Materials and Functional Interfaces

Light scattered by an object contains plethora information about the object which is distributed evenly among all possible Fourier components of light observed in the far‐field. There are some cases, however, where this information is accumulated in the light confined by the object and then encoded in just a few coherent optical beams. Here, Fourier nanotransducers based on 2D plasmonic metamaterials are introduced, which are capable of confining light in 2D plane contacting with a functional interface, gathering information about its properties, and then transmitting the information into discrete optical beams with amplified phase relations. It is shown that phase of light in such beams can be used for probing dynamic physical properties of 2D materials and performing bio/chemical sensing with unprecedented sensitivity. Using a Fourier transducer based on periodic gold nanostructures, ferroelectric response from a single atomic layer of MoS₂ is resolved and studied for the first time, as well as the detection of important antibiotic chloramphenicol at fg mL^?1 level is demonstrated, which several orders of magnitude better than reported in the literature. The implementation of phase‐responsive Fourier nanotransducers opens new avenues in exploration of emergent 2D structures and radical improvement of biosensing technology.     

Sediment penetration performance of a portable underwater robot for core sampling

As described in this paper, we investigate the sediment penetration performance of a portable underwater robot with a helical screw pipe using marine thrusters with limited force. First, we derive a mathematical model based on an empirical and simple method using the undrained shear strength of cohesive soil to provide a rough estimate of maximum penetration depths. Then, we perform numerical analysis for estimating the maximum depth of sediment penetration and for designing a sampling pipe. Additionally, we use experimentation to investigate the relation between the penetration depth of the helical screw pipe and the force of marine thrusters mounted on the portable underwater robot. After testing the penetration performance in a water tank, we conduct a field experiment at Lake Biwa and obtain results of the penetration depths. The maximum penetration into the lake sediment is at least 0.30 m. The results demonstrated the possibility of using the derived mathematical model to make a rough estimation of the maximum penetration depth for clay sediments. Additionally, we can use non-powerful thrusters equipped with small autonomous underwater vehicles (AUVs) and remotely operated vehicles (ROVs) for sediment sampling. The proposed method is also applicable for the installation of underwater sensors using small AUVs and ROVs.     

Corrosion behavior of carbon steel coated with a zinc-rich paint containing metallic compounds under wet and dry cyclic conditions

The corrosion behavior of carbon steel coated with a zinc-rich paint containing two metallic compounds, Al₂(SO₄)₃ and CaO, as anticorrosive additives was examined under wet and dry cyclic corrosion test conditions. The zinc-rich paint coating without the two metallic compounds formed a white corrosion product and red iron rust on the surface after the corrosion test, whereas the coating with the metallic compounds showed reduced surface corrosion products. The corrosion current density of the painted steel substrate decreased drastically due to the incorporation of metallic compounds in the paint. The zinc-rich paint coating modified with the metallic compounds contained dispersed simonkolleite (Zn₅(OH)₈Cl₂·H₂O) phase and possibly very fine CaSO₄ particles, which remarkably improved the protectiveness of the zinc-rich paint coating.     

Cold Atmospheric Plasma Modification of Amyloid β

Cold atmospheric plasma (CAP) has attracted much attention in the fields of biotechnology and medicine owing to its potential utility in clinical applications. Recently accumulating evidence has demonstrated that CAP influences protein structures. However, there remain open questions regarding the molecular mechanisms behind the CAP-induced structural perturbations of biomacromolecules. Here, we investigated the potential effects of CAP irradiation of amyloid β (Aβ), an amyloidogenic protein associated with Alzheimer’s disease. Using nuclear magnetic resonance spectroscopy, we observed gradual spectral changes in Aβ after a 10 s CAP pretreatment, which also suppressed its fibril formation, as revealed by thioflavin T assay. As per mass spectrometric analyses, these effects were attributed to selective oxidation of the methionine residue (Met) at position 35. Interestingly, this modification occurred when Aβ was dissolved into a pre-irradiated buffer, indicating that some reactive species oxidize the Met residue. Our results strongly suggest that the H₂O₂ generated in the solution by CAP irradiation is responsible for Met oxidation, which inhibits Aβ amyloid formation. The findings of the present study provide fundamental insights into plasma biology, giving clues for developing novel applications of CAP.     

Capacitance reduction of pulse voltage generator by using series voltage compensator

This paper proposes a new configuration of a pulse voltage generator, which can be applied to the klystron modulator for a large‐scale accelerator. The voltage generator consists of a conventional capacitor discharge type pulse voltage generator and series cascaded voltage compensators. By using the voltage compensators, higher voltage fluctuation of the bank capacitor is acceptable; therefore, its capacitance and the dimensions of the capacitors can be low. This paper discusses the control strategy of the voltage compensators and thyristors for DC voltage supply for the highly fluctuating capacitor voltage, and demonstrates this by a laboratory‐scale experimental setup.     

一种新的处理非封闭图像表面的三维表面提取算法研究

对皮下组织表面 ,例如表皮·真皮组织交界面进行定性和定量的检测已经越来越成为医学、生物学等诸多学科中有关人体皮肤的课题中不可或缺的重要研究手段 在利用计算机自动检测皮下组织表面的过程中 ,涉及到的一个关键问题就是如何从图像中提取边界成分 动态边界模型 (snake)作为一种边界提取算法被广泛地应用于这类问题中 在这个算法的基础上 ,提出了可以从断层图像中将对象的三维表面提取出来的算法———动态开放表面模型 并应用此算法开发了一套皮下组织表面自动提取重建系统 通过对共焦点显微镜断层图像处理的实验 ,验证了本系统的实用性和可靠性