Induced voltages on fence wires and pipe lines by AC powertransmission lines

A method is developed for calculating the induced voltages on fence wires and pipelines underneath AC power transmission lines. The method is based on the charge simulation techniques and takes into account disturbances of the electric field and potential due to the presence of the fence wire or pipeline underneath the line. The calculated and previously measured induced voltages on fence wires are compared. Induced voltages on pipelines underneath 230 and 380 kV lines were measured. The results are correlated with the calculated values and discussed in the light of electric field induction on objects adjacent to AC power transmission line

Induced voltages on fence wires and pipe lines by AC powertransmission lines

A method is developed for calculating the induced voltages on fence wires and pipelines underneath AC power transmission lines. The method is based on the charge simulation techniques and takes into account disturbances of the electric field and potential due to the presence of the fence wire or pipeline underneath the line. The calculated and previously measured induced voltages on fence wires are compared. Induced voltages on pipelines underneath 230 and 380 kV lines were measured. The results are correlated with the calculated values and discussed in the light of electric field induction on objects adjacent to AC power transmission line

Feasibility study of hybrid retrofits to an isolated off-grid diesel power plant

Abstract The green sources of energy are being encouraged to reduce the environmental pollution and combat the global warming of the planet. A target of 12% usage of wind energy only has been agreed by the UNO country members to achieve by 2020. So, the power of the wind is being used to generate electricity both as grid connected and isolated wind-diesel hybrid power plants. This paper performed a pre-feasibility of wind penetration into an existing diesel plant of a village in north eastern part of Saudi Arabia. For simulation purpose, wind speed data from a near by airport and the load data from the village have been used. The hybrid system design tool HOMER has been used to perform the feasibility study. In the present scenario, for wind speed less than 6.0 m/s the, the existing diesel power plant is the only feasible solution over the range of fuel prices used in the simulation. The wind diesel hybrid system becomes feasible at a wind speed of 6.0 m/s or more and a fuel price of 0.1 $/L or more. If the carbon tax is taken into consideration and subsidy is abolished then it is expected that the hybrid system become feasible. The maximum annual capacity shortage did not have any effect on the cost of energy which may be accounted for larger sizes of wind machines and diesel generators. It is recommended that the wind data must be collected at the village at three different heights using a wind mast of 40m for a minimum of one complete year and then the hybrid system must be re-designed. r 2006 Elsevier Ltd. All rights reserved. ARTICLE IN PRESS www.elsevier.com/locate/rser 1364-0321/$ - see front matter r 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.rser.2005.05.003 Corresponding author. Tel.: +9663 860 3802; fax: +966 3 860 3996. E-mail address: [email protected] (S. Rehman). 1Home page: http://staff.kfupm.edu.sa/ri/srehman

Design and performance evaluation of bitwise retransmission schemes in wireless sensor networks

The previously proposed bitwise retransmission schemes which retransmit only selected bits to accumulate their reliability are designed and evaluated. Unlike conventional automatic repeat request (ARQ) schemes, the bitwise retransmission schemes do not require a checksum for error detection. The bitwise retransmission decisions and combining can be performed either after demodulation of the received symbols or after channel decoding. The design and analysis assume error-free feedback, however, the impact of feedback errors is also considered. The bit-error rate (BER) expressions are derived and verified by computer simulations in order to optimize the parameters of the retransmission schemes. The BER performance of coded and uncoded bitwise retransmissions is compared with a hybrid ARQ (HARQ) scheme over additive white Gaussian noise (AWGN), slow fading, and fast fading channels. It is shown that bitwise retransmissions outperform block repetition coding (BRC) over AWGN channels. In addition, the selection diversity created by the bitwise retransmissions can outperform the HARQ at large signal-to-noise ratio (SNR) over fast fading channels. Finally, the practical design of a bitwise retransmission protocol for data fusion in wireless sensor networks is presented assuming Zigbee, WiFi and Bluetooth system parameters

An ecophysiological study on the moss Hydrogonium fontanum from the Asir mountains, Saudi Arabia

SIGLEAvailable from British Library Document Supply Centre- DSC:D171626 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

The link between shrimp farm runoff and blooms of toxic Heterosigma akashiwo in Red Sea coastal waters

In May 2010 a copious bloom of the raphidophyte Heterosigma akashiwo was observed for the first time in Red Sea waters off the coasts of Saudi Arabia. This bloom was confined to an area where water and phytoplankton flow freely between the sea and a shrimp farm. The phytoplankton density and physico-chemical characteristics of the sea water were therefore investigated weekly at bloom and non-bloom sites in order to gain insight into the environmental factors prevailing at the bloom site and their link with the shrimp farm runoff. The bloom site showed higher nutrient concentrations than the non-bloom site, indicating the possible role of the shrimp farm in flushing nutrients into this site. The bloom appeared on 27 May, coinciding with a decrease in salinity (19◦C). The results of toxicological assays showed that both bloom samples and batch cultures of H. akashiwo were toxic to Artemia salina and exhibited haemolytic activity with respect to rabbit erythrocytes. Bloom samples showed a higher toxicity (LC50 = 8.9 × 104 cells ml−1) and haemolytic activity (EC50 = 3.64 × 104 cells ml−1) than the batch cultures (LC50 =11.6×104 cells ml−1, EC50 =5.1×104 cells ml−1). In the light of the results of this study, the link between H. akashiwo blooms and shrimp farm runoff should be considered during the monitoring of Red Sea coastal waters for the presence of harmful algal blooms

Transmission Lines Magnetic Field Management Feasibility Under Cost Constraints

The scientific issues concerning the relationship between electromagnetic fields and adverse health effects are very complex and difficult to interpret. Epidemiologic data are limited and many results to date are based on small studies with methodological limitations. As a result, there are large differences in the way that these studies are evaluated and interpreted, both within the scientific community in general, and among scientists and Agencies within the federal governments and utilities bodies.This paper contains studies of electromagnetic fields around 138 kV and 230-kV transmission lines and the practical solutions to the field reduction predicted by computer simulation. Chosen were transmission lines 1 and 2 of 138 kV and 230 kV where the data was collected near areas that may be of concern to human occupants. Line 1 consists of two transmission lines of three phase lines. Data was collected with EMDEX II gauss meter approved by EPRI. Analysis of initial measurements was done and compared with simulated data using Southern California Edison's FIELDS program. Feasibility of three new rephasing configurations are evaluated based on the magnitude of magnetic field reduction, the economics, and the practicality. At the edge of the right-of-way, simulation shows a 40 to 80% reduction in magnetic fields. This study demonstrates that rephasing, where applicable, is an effective method to manage magnetic field distribution within, at the edge of, and outside of the transmission line right-of-way. Advantages of each method are presented in this paper with a detail configuration of each simulation, including cost analysis of implementation of such designs

Transmission Lines Magnetic Field Management Feasibility Under Cost Constraints

The scientific issues concerning the relationship between electromagnetic fields and adverse health effects are very complex and difficult to interpret. Epidemiologic data are limited and many results to date are based on small studies with methodological limitations. As a result, there are large differences in the way that these studies are evaluated and interpreted, both within the scientific community in general, and among scientists and Agencies within the federal governments and utilities bodies.This paper contains studies of electromagnetic fields around 138 kV and 230-kV transmission lines and the practical solutions to the field reduction predicted by computer simulation. Chosen were transmission lines 1 and 2 of 138 kV and 230 kV where the data was collected near areas that may be of concern to human occupants. Line 1 consists of two transmission lines of three phase lines. Data was collected with EMDEX II gauss meter approved by EPRI. Analysis of initial measurements was done and compared with simulated data using Southern California Edison's FIELDS program. Feasibility of three new rephasing configurations are evaluated based on the magnitude of magnetic field reduction, the economics, and the practicality. At the edge of the right-of-way, simulation shows a 40 to 80% reduction in magnetic fields. This study demonstrates that rephasing, where applicable, is an effective method to manage magnetic field distribution within, at the edge of, and outside of the transmission line right-of-way. Advantages of each method are presented in this paper with a detail configuration of each simulation, including cost analysis of implementation of such designs