The fracture energy and acoustic emission of a short carbon fiber reinforced nylon 66 composite

Two knee points which are found in the cumulative plotting of acoustic emission (AE) events on a semi-log sheet in a monotonically increasing tensile load system of the center notched carbon fiber reinforced nylon 66 composite (FRTP) are applied to the estimation of the energy value required for the beginning of the stable crack propagation, the one for the stable crack propagation and also the one for the final fracture. They have been examined with regard to the dependence of some mechanical properties of the material on the gauge length, the fiber content and the crack length to width ratio of the specimen. Correlations between the AE characteristic nature such as AE activity (the number of AE events per unit area) and the above energy values are also investigated with regard to the results of the fractographic measurement of the fracture surface. It has been found that the energy required for the stable crack propagation decreases with an increase in the crack length to width ratio and increases with an increase in the gauge length. However, for an unstable crack propagation, it decreases with an increase in the fiber content. The dependence of the energy value on crack length to width ratio disappears in the results for a 30% specimen and this value becomes constant.     

Development of a compact high-density microbial hydrogen reactor for portable bio-fuel cell system

The development of a compact high-density microbial reactor for hydrogen production is described with possible implications to use as a portable bio-fuel cell system. To construct the compact bioreactor, mainly, the cell density and immobilization methods were optimized in this paper. The encapsulation of hydrogen producing bacterium, Escherichia coli strain MC13-4, in alginate gel beads provided approximately three-fold increase in hydrogen production in comparison with the free cell suspension. The immobilized cells (cell density; O.D. 100) and 500 mM glucose solution were packed into a 20 mL glass bottle that was connected to the fuel cell. This system has generated electricity of over 20 mW for 20 min.     

Structural characteristics of Hagia Sophia: II—A finite element formulation for dynamic analysis

The Hagia Sophia, a 6th century masonry edifice in Istanbul, is analysed with a linear finite element model including thickness shear deformations, the terms z/R, and rotatory inertia effects with consistent mass matrix to provide insight to the structure's behaviour under earthquake loading. The structure, including the primary main dome and supporting system, is modelled by using a two-dimensional model composed of eight-node shell element. The dynamic characteristics of the system are obtained by using the Wilson-θ method, step-by-step integration method, and also by applying the available ground motion data to understand its general structural behaviour in the future earthquakes.     

A study of transfer switching for the purpose of fault detection in FRIENDS

The authors have proposed a new concept of a distribution system “Flexible, Reliable and Intelligent ENergy Delivery System (FRIENDS)” with intent to solve imminent operating problems faced by utilities in providing their customers with reliable supply of power at several levels of quality. The main idea of FRIENDS is to introduce new facilities, so‐called Quality Control Centers (QCCs), which are installed very close to the customers for the purpose of implementing multiple functions, such as Customized Power Quality Service. In addition, these QCCs form a network for energy and information transmission at a level below distribution substations. QCCs make it possible to frequently change configuration of the network depending on the system and load conditions. These frequent reconfigurations of the network require fast and reliable Transfer Switching in the QCCs to ease an effect on customers. The reconfiguration for the purpose of fault area isolation also requires a fast Fault Detection feature. This paper presents a new method for controlling Transfer Switching and a method of Fault Detection in order to realize a fast and reliable reconfiguration of QCC network in a normal state, as well as under fault conditions. This paper also analyzes the methods in terms of instantaneous values calculated by PSCAD/EMTDC. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 148(3): 25–35, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10298     

Ultra micro glutamate sensor using platinized carbon-fiber electrode and integrated counter electrode

An integrated ultra micro glutamate sensor has been constructed with a 7 μm diameter platinized carbon-fiber disk (PCD) electrode and a platinum thin-film (PTF) counter electrode fabricated on the glass capillary tube. By platinization, the electrode activity of the carbon fiber is improved. In order to obtain a stable response, a pulse potential is applied for hydrogen peroxide measurement. The PTF counter electrode shows good stability and can be used as a substitute for a silver-silver chloride electrode. Since the integrated PCD electrode shows good characteristics as a hydrogen peroxide sensor, glutamate oxidase is immobilized onto the tip of the PCD electrode to construct the ultra micro glutamate sensor. The sensor shows stable response to glutamate and a response time within 12 s. The calibration range for glutamate measurement is 50–800 μM.