Gas-Coupled, Pulse-Echo Ultrasonic Crack Detection and Thickness Gaging

Ultrasonic inspection is a standard method to assess the integrity of large-diameter oil pipelines. However, similar methods applied to natural-gas pipelines present a considerably greater challenge; gas is a poor coupling agent for the probing ultrasonic signals between the transducer and the pipe wall. Natural gas exhibits a very low specific acoustic impedance (300 Rayls for methane at atmospheric pressure) compared to oil (1.5 MRayls and higher). Consequently, large ultrasonic-signal transmission losses occur at the transducer/gas and pipe-wall/gas interfaces. To circumvent this obstacle, past exploratory developments included the use of a liquid-filled wheel [1], electromagnetic-acoustic-transducer (EMAT) [2], and liquid-slug technologies [3]. While prototypes of high-speed, in-line inspection systems employing such principles do exist, all exhibit serious operational shortcomings that prevent widespread commercial exploitation.</p

Gas-Coupled, Pulse-Echo Ultrasonic Crack Detection and Thickness Gaging

Ultrasonic inspection is a standard method to assess the integrity of large-diameter oil pipelines. However, similar methods applied to natural-gas pipelines present a considerably greater challenge; gas is a poor coupling agent for the probing ultrasonic signals between the transducer and the pipe wall. Natural gas exhibits a very low specific acoustic impedance (300 Rayls for methane at atmospheric pressure) compared to oil (1.5 MRayls and higher). Consequently, large ultrasonic-signal transmission losses occur at the transducer/gas and pipe-wall/gas interfaces. To circumvent this obstacle, past exploratory developments included the use of a liquid-filled wheel [1], electromagnetic-acoustic-transducer (EMAT) [2], and liquid-slug technologies [3]. While prototypes of high-speed, in-line inspection systems employing such principles do exist, all exhibit serious operational shortcomings that prevent widespread commercial exploitation

Content Engineering Agent: A TBL-Based E-Course Development Tool with TQM

With the advance in Internet technology, “e-learning” becomes an alternative means of learning and teaching, and is currently an active research topic in both IT and education professionals. However, to make “e-learning” an effective learning mode, besides technology, the issue of pedagogy and quality control are equally important. Most of the existing e-learning platforms and tools usually focus on the technology aspect without much investigation on the pedagogical issues and the quality control on the e-learning material. In fact, there is still a big gap between pedagogy and technology. The SPACE Online Universal Learning (SOUL) platform is designed to fill this gap and provide an effective e-Learning platform for e-course providers and students. In particular, the content engineering agent of the platform is designed for e-course development, which is based on the Task-Based Learning (TBL) curriculum development framework and is incorporated with the concept of Total Quality Management (TQM), a well-known technique in quality control. In this paper, we discuss the details of this content engineering agent and show how TBL and TQM are incorporated in the agent. As a remark, the content engineering agent has already been integrated in the SOUL platform, which is being used by more than 17,000 students and teachers. A preliminary evaluation on the usefulness of the Content Engineering agent has been performed and the result is positive