The University of the West Indies-Seismic Research Centre Volcano Monitoring Network: Evolution since 1953 and Challenges in Maintaining a State-of-the-Art Network in a Small Island Economy

The Seismic Research Centre (SRC), formerly known as the Seismic Research Unit (SRU), of the University of the West Indies is located on the island of Trinidad in the Eastern Caribbean. The centre has been operating its volcanological and seismological surveillance network since 1953. Since that time, the network has been upgraded five times resulting in five generations of seismic network topologies (i.e., Classes). Class 1 consisted of autonomously operated photographic recording stations, a purely analogue configuration. From Class 2 to Class 5 (current class) the network has continuously grown in scope, sophistication and capability. The evolution of the network was carried out using a combination of state-of-the-art instruments as well as trailing edge technology (e.g., analogue transmission) used in a manner that allows for sustainability. In this way, the network has been able to address the scientific and technical challenges associated with operating in an island arc subduction zone which is exposed to other natural hazards such as hurricanes. To counter its operational constrains the SRC has developed several strategies, which contribute to: (i) expand the network to meet the demand for more timely and accurate surveillance of geohazards, (ii) broaden the range of monitoring techniques (e.g., cGPS, geochemical), (iii) capture research grade scientific data and (iv) reduce operational costs.

Hardware Development Of Electrical Capacitance Tomography For Imaging A Mixture Of Water And Oil

Kertas kerja ini membentangkan kajian perubahan nilai kapasitan terhadap pengukuran perbezaan bahan dielektrik seperti minyak dan air di dalam saliran paip menggunakan 12 pengesan elektrod di atas permukaan paip. Sistem Kapasitan Elektrik Tomografi (ECT) berupaya memaparkan pembentukan imej di dalam industri proses campurankomponen yang melibatkan cecair bukan pengalir di dalam paip. Oleh yang demikian, menerusi kajian ini, 12 elektrod kapasitan elektrik tomografi dibangunkan. Sistem ini membolehkan banyak data diperolehi bagi pembentukan imej yang lebih jelas di dalam aliran paip. Untuk mengurangkan hingar di dalam sistem ini, litar perapi telah di bina di atas plat pengesan di atas satu plat yang sama bagi menghilangkan sebahagian hingar yang datang dari talian penghantaran isyarat analog. Setelah itu pelbagai litar pengukur kapasitan telah dibina dari segi prestasi dan kepekaannya bagi memperolehi aras hingar yang rendah, kadar dinamik yang luas dan imun kepada kebocoran kapasitan bagi memenuhi reka bentuk yang sempurna untuk sistem yang dibina. Isyarat yang terhasil dari litar pengesan di tukar dalam bentuk digital menerusi litar multiplex, penukar analog kepada digital dan penampan maka dengan itu data yang dihantar bersesuaian dengan pengantaramukaan computer. Pengantaramukaan pengguna grafik (GUI) dibina dengan pengawal dan penunjuk yang lebih jelas member kemudahan kepada pengguna berinteraksi dengan panel kawalan. Kata kunci: Kapasitan tomografi; 12 elektrod; plat pengesan; perapi atas satu plat This paper proposes the process of investigating the changes of capacitance value due to the changes of permittivity distribution of a different dielectric materials such as water and oil in a conveying pipeline using twelve externally Electrical Capacitance Tomography (ECT) sensor. Electrical capacitance tomography system is a system which can be used for imaging industrial multi–component processes involving non-conducting fluids in pipeline. Therefore, in this research, a 12 electrodes electrical capacitance tomography system is developed. This system can provide more data for processing to obtain more precise images of the pipeline. In order to reduce the noise in the system, on–plate signal conditioning board is applied in this research to eliminate certain noise source from the analogue transmission line. Then, various of accapacitance measuring circuits has been developed in terms of performance and sensitivity to achieve low noise level, wide dynamic range and high immunity stray capacitance to suits the appropriate design for system development. The signal produced by the detection circuit is digitized by using multiplexing circuit, ADC circuit and buffering so that the transferring data is suitable for pc interface. A graphic user interface (GUI) is developed with visible controls and indicators to provide users with organized interactive panels. Key words: Capacitance tomography, 12 electrodes, on-plate signal conditioning board

Broadcast Digital Migration Policy in South Africa

All countries in the world, are compelled to migrate their analogue terrestrial television systems to digital by the year 2015 as stipulated by the International Telecommunications Union. The old analogue transmission signals will be eventually switched off and so countries need to upgrade their television systems so that they can receive digital signals. This has necessitated government intervention in the form of policies or strategies to manage this transition process from analogue to digital. This chapter looks at the transition from analogue to digital terrestrial television migration in South Africa. It considers South Africa’s Digital Migration Policy as a framework meant to advance the introduction of digital terrestrial television. Since the process is still in motion and we are looking at a start of a transition period towards the eventual cut-off date of analogue signals in 2015, there are therefore no definite conclusions about whether the South African case can be considered entirely successful. The effort of this chapter is merely to gauge the policy effort and rollout activities made thus far towards digital migration, highlighting potential drawbacks.