Nagoya Institute of Technology

About: Nagoya Institute of Technology is a education organization based out in Nagoya, Japan. It is known for research contribution in the topics: Thin film & Catalysis. The organization has 10766 authors who have published 19140 publications receiving 255696 citations. The organization is also known as: Nagoya Kōgyō Daigaku & Nitech.

PWM Switching Technique for Three-Phase Bidirectional Grid-Tie DC–AC–AC Converter With High-Frequency Isolation

Abstract: Galvanic isolation based high-frequency transformers have become very attractive in bidirectional dc/ac converters. This paper presents a new pulse width modulation (PWM) switching technique for controlling a bidirectional isolated dc–ac–ac converter employing a high-frequency link transformer. The proposed PWM technique has the ability to control the input dc current and to inject a sinusoidal three-phase current to the grid at unity power factor. The primary-side is an H-bridge converter used to convert the dc voltage to a high-frequency square-wave single-phase voltage. The secondary side is a matrix converter used to convert the grid three-phase voltage to a high-frequency single-phase waveform. The dc–ac–ac converter utilizes a high-frequency link transformer for the galvanic isolation between the H-bridge and matrix converters as alternative for the bulky line-frequency transformers (50/60 Hz). The bidirectional power flow is controlled by the phase shift angle between the primary and secondary voltages of the high-frequency transformer. The mathematical model and the circuit operational modes are presented along with the voltage controllable limit. The feasibility of the proposed PWM switching technique and the accuracy of the mathematical model are demonstrated experimentally by using a 200 V/1 kW laboratory prototype system.

Protonic conduction in alkaline earth metaphosphate glasses containing water

Abstract: D.c. electrical conductivity data were obtained for M O·P 2 O 5 glasses ( M = Be, Mg, Ca, Sr, Ba) containing small amounts of water. The results suggest that the mobility of protons in the glasses increases with decreasing OH bonding strength. The relation between the proton concentration and the conductivity or the apparent activation energy was studied for calcium metaphosphate glasses containing various amounts of water. The conductivity was found to be proportional to the square of the proton concentration; the apparent activation energy decreased linearly with increasing logarithm of proton concentration.

Antimicrobial activity of the extracts and physalin D from Physalis alkekengi and evaluation of antioxidant potential of physalin D.

Abstract: Physalis alkekengi L. (Solanaceae) is a popular plant in traditional European and Chinese folk medicine, and it has been reported to have many ethnopharmacological properties including antifungal, anti-cough, anti-inflammatory, analgesic, and febricide activities. Some active components from Physalis species have been investigated. However, no antimicrobial activity studies on extracts and physalins of P. alkekengi have been carried out. In this study, we attempted to identify the possible antimicrobial activities of the methanol extract from aerial parts of P. alkekengi and the dichloromethane extract from calyces of the plant. The extracts were tested against five Gram-positive and five Gram-negative bacteria and five Candida species by using disk diffusion and broth microdilution methods. The extracts were fractionated to isolate physalins using chromatographic techniques, and physalin D was isolated from the extracts. The structure of the compound was elucidated on the basis of (1)H-NMR spectroscopic study, and confirmed by comparison with a reference sample and literature data. Results indicated that all the extracts and physalin D were characterized by antibacterial action, especially against Gram-positive bacteria, with MIC values between 32 and 128 microg/mL. The methanol extract had moderate activity against fungi at MICs ranging from 128 to 512 microg/mL, but the dichloromethane extract and physalin D had low activity against fungi at MICs ranging from 256 to 512 microg/mL. Additionally, the antioxidant activity of physalin D was evaluated by qualitative DPPH (1,1-diphenyl-2-picrylhydrazyl) radical and TBA (thiobarbituric acid) assays. Physalin D showed low antioxidant activity with an IC(50) value of >or= 10 +/- 2.1.

Effect of Fiber Waviness on the Nonlinear Elastic Behavior of Flexible Composites

Abstract: The effect of fiber waviness on the elastic moduli of flexible composites is investigated theoretically and experimentally. The flexible composites examined are composed of con tinuous fibers with sinusoidal waviness in an elastomeric matrix. Both iso-phase and random-phase fiber arrangements are used for this study. The constitutive relations for the longitudinal and transverse tensile behavior have been developed for these models. Tensile tests have been conducted to verify the constitutive relations. Carbon fiber and silicone elastomer were used for the experiments. Techniques for specimen fabrication as well as photoelastic tests are also presented. Experimental results show good agreement with the theoretical predictions.

Randomized Leader Election Protocols in Radio Networks with No Collision Detection

Abstract: The main contribution of this work is to propose energy-efficient randomized leader election protocols for single-hop, single-channel radio networks (RN) that do not have collision detection (CD) capabilities We first presents a leader election protocol for the case the number n of stations is known beforehand The protocol runs in O(log f) time slots with no station being awake for more than O(log log f + log f/log n) time slots with probability at least 1 - 1/f for any f ≥ 1 We then present three leader election protocols for the case where n is not known beforehand The first protocol terminates, with probability exceeding 1 - 1/f, in O((log n)2 + (log f)2) time slots, with no station being awake for more than O(log n + log f) time slots Clearly, this first protocol terminates in O((log n)2) expected time slots Our second protocol reduces the expected termination time to O(log n) time slots This second protocol terminates, with probability exceeding 1 - 1/f in O(f3/5 log n) time slots Finally, by combining these two protocols, we obtain a third leader election protocol that terminates in O(log n) expected time slots This latter protocol terminates, with with probability exceeding 1 - 1/f, in O(min((log n)2 + (log f)2, f3/5log n)) time slots, with no station being awake for more than O(log n + log f) time slots