The pump performance and occurrence of cavitation directly depends on different operating conditions. To cover a wide range of operation conditions for detecting cavitation in this work, investigations on the effect of various suction valve openings on cavitation in the pump were carried out. In order to analyse various levels of cavitation in different operation conditions, the effect of the decrease in the inlet suction pressure of the centrifugal pump by controlling the inlet suction valve opening was investigated using this experimental setup. Hence, the acoustic and pressure signals under different inlet valve openings and different flow rates, namely, 103, 200, 302 l/min were collected for this purpose. A detailed analysis of the results obtained from the acoustic signal was carried out to predict cavitation in the pump under different operating conditions. Also, the acoustic signal was investigated in time domain through the use of the same statistical features. The FFT technique was used to analyse the acoustic signal in the frequency domain. In addition, in this work an attempt was made to find a relationship between the cavitation and noise characteristics using the acoustic technique for identifying cavitation within a pump.
The very wet conditions of recent years in Europe have made it clear that measures will have to be taken in this century to prevent flooding. The question is how to manage groundwater in order to reduce the anticipated increased hydrological risk. Furthermore the surface water quality in the Netherlands is insufficient to meet the standards of the Water Framework Directive. The required improvements are difficult to reach, because the diffuse loads of nutrients from agricultural land can not be easily reduced. This demands for innovative solutions with respect to improve the surface wa-ter quality. In this pilot study the focus is on the purification in reed fields and use it as well to reduce the effects of the anticipated climate change. An experimental evidence on a practical scale is lacking and therefore in the woodland area of Lankheet in the eastern part of the Netherlands, 3 ha has been planted with reeds to purify the river water. The aim of the study is further to store the purified water in the groundwater in order to reduce climate change effects. For the hydrological situation a scenario study was set up, using a regional hydrological model to simulate the groundwater flow together with the water flow in a network of water courses. The analysis will give knowledge on the multifunc-tional use of such a system.
The Opole region struggles from the most unfavourable demographic situation among all Polish administrative regions. The region is not only losing its population but also reports a growing number of inhabitants aged 50 and more. For this reason, demographic challenges are high on the region’s development agenda. The establishment of the Special Demographic Zone for Opolskie Voivodeship (SDZ) has provided an incentive to take measures, both on the local and regional scale, to reverse the undesirable situation.
This article discusses one of the SDZ packages, namely Package 4 Golden Autumn intended for persons aged 50 and move. Based on surveys held in the municipalities of the Opole region, the author seeks to answer questions related to the perception of the existing demographic processes as developmental barriers and looks at different initiatives and action taken by local self-governments for 50+ residents.
The paper concerns the two-machine non-preemptive flow shop scheduling problem with a total late work criterion
and a common due date (F2|dj = d|Y ). The late work performance measure estimates the quality of a solution with regard
to the duration of late parts of activities performed in the system, not taking into account the quantity of this delay. In the
paper, a few theorems are formulated and proven, describing features of an optimal solution for the problem mentioned, which is
NP-hard. These theorems can be used in exact exponential algorithms (as dominance relations reducing the number of solutions
enumerated explicitly), as well as in heuristic and metaheuristic methods (supporting the construction of sub-optimal schedules
of a good quality).
The aim of this study was to compare and analyze the gasification process of beech wood. The experimental investigation was conducted inside a gasifier, which can be operated in downdraft and updraft gasification system. The most important operating parameter studied in this paper was the influence of the amount of supply air on the temperature distribution, biomass consumption and syngas calorific value. The results show that the amount of air significantly influences the temperature in the combustion zone for the downdraft gasification process, where temperature differences reached more than 150 ◦C.The increased amount of air supplied to the gasifier caused an increase in fuel consumption for both experimental setups. Experimental results regarding equivalence ratio show that for value below 0.2, the updraft gasification is characterized by a higher calorific value of producer gas, while for about 0.22 a similar calorific value (6.5 MJ/Nm3) for both gasification configurations was obtained. Above this value, an increase in equivalence ratio causes a decrease in the calorific value of gas for downdraft and updraft gasifiers.