Debond detection in RC structures using piezoelectric materials

This paper presents a technique to detect the delamination between the steel bars and concrete in the reinforced concrete structures. The piezoelectric components are mounted on reinforcing bars that are embedded in RC structures as sensors and actuators to generate and record the signal, which is sensitive to the delamination between the steel bars and concrete. The experimental study is carried out on a concrete slab with different debonds between the rebars and concrete. The test results show that the delamination between the rebars and concrete can be detected with the embedded piezoelectric sensors and actuators.

Some aspects of numerical simulation for lamb wave propogation in composite laminates

Some aspects of numerical simulation of Lamb wave propagation in composite laminates using the finite element models with explicit dynamic analysis are addressed in this study. To correctly and efficiently describe the guided-wave excited/received by piezoelectric actuators/sensors, effective models of surface-bounded flat PZT disks based on effective force, moment and displacement are developed. Different finite element models for Lamb wave excitation, collection and propagation in isotropic plate and quasi-isotropic laminated composite are evaluated using continuum elements (3-D solid element) and structural elements (3-D shell element), to elaborate the validity and versatility of the proposed actuator/sensor models.

What do they think when we stack them in? A comparative analysis of student perceptions relating to large and small marketing subjects

University education is in a period of flux with emphasis being focused on quality education, competition for students both local and international as well as changes in governmental financial support and direction. It is with this scenario as a backdrop, that universities in an endeavour to obtain economies of scale offer subjects with large student enrolments. This study investigates marketing students’ perception of and participation in marketing subjects relating to teaching quality, staff availability and support, and individual student involvement in marketing education with large enrolments compared to subjects with small enrolments. This research builds on the investigations of effects of class size by Cuseo (2004) and Binney et al (2004). The study used a multi-method approach. Data from a sample of 621 students was analysed using Factor analysis, MANOVA and ANOVA. Students indicated that there was little difference in the quality of learning obtained in small or large classes. Of interest from a marketing perspective, however, is the perception by students that they are more likely to obtain practical assistance and support from tutors in smaller classes. Student perceptions generally show no major differences between large and small classes in relation to subject selection, ability to learn and lecture  attendance. Students expressed a preference for the opportunity to choose from a number of lecture streams available in subjects with large enrolments. Of interest, however is the student belief that they are less likely to actively participate in large lectures than in small lecture environments.

Enhancement of natural ventilation in high-rise residential buildings using stack system

This paper describes the feasibility study on the application of passive and active stack systems to enhance natural ventilation in public housing in Singapore. About 86% of the population is staying in high-rise public housing, known as Housing and Development Board (HDB) flats, which is designed for natural ventilation. The primary objective of this work is to assess the status of natural ventilation in a typical four-room HDB flat using scaled model in the wind tunnel, and to develop an effective passive or active stack system to enhance natural ventilation in the flat. Four numbers of stacks with different sizes were tested at two locations in the flat. The study shows that the passive stack, incorporating the principle of airflow due to buoyancy, does not enhance air velocity in the flat. However, the active stack which operates based on the suction effect induced by a fan fixed at the top of the stack leads to substantial increase in the air velocity at the room and thus meeting the human’s thermal comfort condition. It was noted that the velocities increase along with the increase in the stack size.

A potential application of a piezoelectric atomiser for ophthalmic drug delivery

A liquid atomiser composed of a piezoelectric transducer and a metal plate with numerous micro-apertures is studied to identify the most influential factors on its atomising performance. The Taguchi method is employed in the experiment design and analysis of the study on how each factor acts in the atomising process. An optimal condition is determined for producing a stream of droplets. The study shows that the droplet size and the spraying velocity are suitable for ophthalmic drug delivery application, with an even distribution of the drug over most of the eyeball surface area due to the controllable cross-sectional area of the droplet stream. This greatly improves the treatment effectiveness and efficiency of eye therapy. Finally, a structure of the ophthalmic drug delivery system is proposed.

Solid state actuators based on polypyrrole and polymer-in-ionic liquid electrolytes

Novel polymer-in-ionic liquid electrolytes (PILEs) have been developed for solid state electrochemical actuators based on polypyrrole. The active polymer electrodes are readily oxidized/reduced without degradation in the PILE. It was found that the actuator cycle life is significantly enhanced in the PILE as is the ‘shelf life’ of the device.

Real-time surface formation using a network of interconnected programmable actuators

This research has explored methods for developing a large interactive dynamic 3D surface using an array of interconnected pneumatically actuated cylinders. People can control the surface using body movement, sound or pre-programmed sequences. The main contribution is a method for accurately positioning cylinders without the need for position feedback.