Women in the December 26 Tsunami: how have they coped; how can we help?

Fishing communities around the Indian Ocean were severely affected by the December 2004 tsunamis. Programs for rebuilding coastal fisheries livelihoods need to address the pre-tsunami situation that was characterized by overfishing and degraded natural resources. Adopting appropriate strategies to ensure sustainable livelihoods will require community involvement, as well as cross-sectoral, integrated planning and management at ascending government levels. Key recommendations from the WorldFish Center study Sustainable Management of Coastal Fish Stocks in Asia are presented to encourage discussion and debate

Development of personal area network (PAN) for mobile robot using bluetooth transceiver

The work presents the concept of providing a Personal Area Network (PAN) for microcontroller based mobile robots using Bluetooth transceiver. With the concept of replacing cable, low cost, low power consumption and communication range between 10m to 100m, Bluetooth is suitable for communication between mobile robots since most mobile robots are powered by batteries and have high mobility. The network aimed to support real-time control of up to two mobile robots from a master mobile robot through communication using Bluetooth transceiver. If a fast network radio link is implemented, a whole new world of possibilities is opened in the research of robotics control and Artificial Intelligence (AI) research works, sending real time image and information. Robots could communicate through obstacles or even through walls. Bluetooth Ad Hoc topology provides a simple communication between devices in close by forming PAN. A system contained of both hardware and software is designed to enable the robots to form a PAN and communicating, sharing information. Three microcontroller based mobile robots are built for this research work. Bluetooth Protocol Stack and mobile robot control architecture is implemented on a single microcontroller chip. The PAN enabled a few mobile robots to communicate with each other to complete a given task. The wireless communication between mobile robots is reliable based from the result of experiments carried out. Thus this is a platform for multi mobile robots system and Ad Hoc networking system. Results from experiments show that microcontroller based mobile robots can easily form a Bluetooth PAN and communicate with each other

Electric Field Determination in DC Polymeric Power Cable in the Presence of Space Charge

The pulsed electroacoustic (PEA) technique was used to perform space charge measurements in polymeric power cables. However, for a practical dc power cable the electric field is affected by conductivity of the material, which is a function of both temperature and electric field. The coupled problems inflict difficulties to identify the electric field distribution in high voltage (HV) cables, which therefore poses threat to the reliability in operation of dc power cables. In this paper we proposed a method of determining electric field distribution in XLPE power cable, where under temperature gradient the existence of space charge density of the cable is determined by means of a modified PEA system. Commercial 11 kV ac XLPE power cable is applied and measured under an applied dc voltage of 80 kV. The space charge across the insulation was obtained and COMSOL Multiphysics software package is used to accurately determine the electric field distribution in the dc power cable by considering the influences of both the effects of temperature and electric field on the conductivity of the insulating material. Therefore, the results of the numerical modelling shall give us a clearer representation of the electric field distribution in HVDC cables

Constant beamwidth generalised sidelobe canceller

In this paper, we proposed a constant beamwidth discrete Fourier transform (DFT) beamformer based on the generalised sidelobe canceller (GSC). Broadband signals are decomposed into frequency bins which are grouped into octaves and tapered individually. The resulting beampattern possesses constant beamwidth across the entire operating spectrum, thus ensuring uniform spatial resolution. Further incorporation of the GSC allows adaptive nulling of interference to coincide with uniform resolution, enhancing the beamformer’s performance. However, modification to the constraint equation of the standard GSC is required to account for the frequency-dependent weighting of sensors

Space Charge Accumulation under Effects of Temperature Gradient and Applied Voltage Reversal on Solid Dielectric DC Cable

A well-known fact of the existence and accumulation of space charge within the insulating material poses threat to the reliability in the operation of dc power cables. When power cables are loaded under high voltage direct current (HVDC), temperature gradient is developed across the insulation. Results of space charge evolution in commercial ac XLPE power cables under an application of 80 kV dc supply at different temperature gradients and during external voltage reversal are discussed in this paper. The space charge distributions were measured across the insulation of the cable by means of a modified pulsed electroacoustic (PEA) system with a current transformer attached. Therefore, a replica of a power cable under load conditions could be obtained, which allows us to investigate the formation, migration and accumulation of space charges in a power cable both without and with different temperature gradients consideration across the bulk of the insulating material during voltage reversal. Discussion will be made thoroughly in order to understand the space charge phenomenon of power cable under its service temperature as space charge accumulation during polarity reversal plays an important factor on the electric field distribution within the insulation material

Space charge accumulation under the effects of temperature gradient on solid dielectric DC cable

It is well known that existence and accumulation of space charge within the insulating material poses threat to the reliability in the operation of dc power cables. When the cables are loaded under high voltage direct current (HVDC), temperature gradient is developed across the insulation material. In this paper, commercial ac XLPE power cables were used under an application voltage of 80 kV dc with different temperature gradients loaded between the insulating material. Space charge distributions were then measured across the insulation of the cable by means of a modified pulsed electroacoustic (PEA) system with a current transformer attached. Therefore, a replica of a power cable under load conditions could be obtained, which allows us to investigate the formation, migration and accumulation of space charges in a power cable both without and with different temperature gradients consideration across the bulk of the insulating material. Discussion will be made thoroughly in order to understand the space charge phenomenon of power cable under its service temperature

Prior Conditions, Age and the Impact of Insurance

Health insurance coverage reduces the price perceived by the insured and consequently increases the quantity of health care demanded. We consider vision care insurance because this provides a unique opportunity to observe the differential response to insurance coverage by those with and without a prior medical condition. The results show that there is a response by both groups and the response is larger for those with a prior condition. We also find that vision care insurance is poorly matched in time to the patterns of vision care needsHealth Insurance, Vision Care, Prior Conditions