Monitoring Support for Water Distribution Systems based on Pressure Sensor Data

Water Resources Management - The increasing age and deterioration of drinking water mains is causing an increasing frequency of pipe bursts. Not only are pipe repairs costly, bursts might also lead...     

Excitation system of asynchronized turbogenerators

In contrast to conventional synchronous turbogenerators, an asynchronized turbogenerator can operate for a long time with a disabled excitation system and short-circuited longitudinal-lateral rotor windings, which increases substantially the operational reliability. The requirements on the power and information equipment of the excitation system with respect to redundancy are also less strict. Computer simulation of emergency conditions in an asynchronized turbogenerator has made it possible to substantiate the requirements on the speed of response to current reversal in the excitation system and to recommend an algorithm for protection performance upon transition of the turbogenerator to the standby mode.Translated from Élektricheskie Stantsii, No. 9, September 2004, pp. 67–72.     

The state of the left-bank anchor reinforcement of the Chirkeiskaya hydrosystem

The state of reinforcement anchors after 30 years of service at the hydroelectric power plant is described, and tension variations in the bars placed in adits caused by high humidity, breaking of welds, seismic, etc. are analyzed.Translated from Gidrotekhnicheskoe Stroitelstvo, No. 9, September 2004, pp. 52–55.     

Asynchronized machines as a means of counter-emergency control and frequency regulation in a power system

The possibility of using asynchronized machines, operating with a variable rotor rotation frequency, as counter- emergency control and high-speed regulation of the active power, is shown. The problems involved in using asynchronized machines to increase the active power and frequency regulation quality, and also to improve the dynamic characteristic of power systems, are considered.     

Analysis of physical processes and operating behavior of gas turbine units with high loading of the gas turbine stage

Aspects of using a highly loaded stage in place of a group of stages in gas turbines are analyzed. Experimental data for individual wheels, as well as for the entire stage as a whole, are presented which confirm the possibility of obtaining efficiencies relative to braking of 0.87 – 0.89 during operation of the stage with turbine load parameters of 0.40 – 0.48. This makes it possible to reduce the number of stages without significant loss of gas dynamic efficiency. The cooling air feed rate is lowered and fewer parts are needed, thereby reducing the cost of the entire turbine.     

Estimating the Economic Value of Landscape Losses Due to Flooding by Hydropower Plants in the Chilean Patagonia

This paper presents a contingent valuation study concerning landscape impacts generated by the construction of one dam (Baker 1) of the HIDROAYSEN hydropower project located in the Chilean Patagonia. A survey was used to collect information about citizens’ opinions towards the hydropower project in four major cities in Chile. Specifically, a One-and-One-Half-Bound (OOHB) willingness to pay eliciting format was applied to capture citizens’ WTP. The economic loss, associated to the landscape impacts for people living in urban areas of the country, is found to be approximately US$ 205 million, which is nearly 28% of the total investment. Our results also show that the cities’ distance from the dam affects citizens’ willingness to pay.     

Analysis of shear stress and energy consumption in a tubular airlift membrane system

Application of a two-phase slug flow in side-stream membrane bioreactors (MBRs) has proven to increase the permeate flux and decrease fouling through a better control of the cake layer. Past literature has shown that the hydrodynamics near the membrane surface have an impact on the degree of fouling by imposing high shear stress near the surface of the membrane. Previously, shear stress histograms (SSH) have been introduced to summarize results from an experimental setup developed to investigate the shear stress imposed on the surface of a membrane under different two-phase flow conditions (gas and liquid) by varying the flow of each phase. Bimodal SSHs were observed, with peaks corresponding to the shear induced by the liquid and gas flow respectively. In this contribution, SSHs are modelled using simple empirical relationships. These are used to identify the two-phase flow conditions that optimize fouling control. Furthermore, the total energy consumption of the system was estimated based on the two-phase pressure drop. It was found that low liquid and high gas flow rates (ratio of approx. 4) balanced the peaks and minimized the energy consumption.     

Design and construction of an experimental pervious paved parking area to harvest reusable rainwater

Pervious pavements are sustainable urban drainage systems already known as rainwater infiltration techniques which reduce runoff formation and diffuse pollution in cities. The present research is focused on the design and construction of an experimental parking area, composed of 45 pervious pavement parking bays. Every pervious pavement was experimentally designed to store rainwater and measure the levels of the stored water and its quality over time. Six different pervious surfaces are combined with four different geotextiles in order to test which materials respond better to the good quality of rainwater storage over time and under the specific weather conditions of the north of Spain. The aim of this research was to obtain a good performance of pervious pavements that offered simultaneously a positive urban service and helped to harvest rainwater with a good quality to be used for non potable demands.     

Calculation of Maximum Permissible Load Currents under Cyclic Loading Conditions for Cables Laid in the Ground and in Pipes in the Ground

A method for calculating the maximum permissible load current under the conditions of cyclic daily load curve is developed. A system is suggested for parallel cables laid in the ground, including in pipes. The coefficients for determining permissible load currents are calculated for different laying variants. Calculated data for cables arranged in 2 × 2 and 2 × 4 blocks are presented.