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Number of results: 10
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Abstract

The paper presents a thermodynamic analysis of the removal of an inert gas from the tank using the vapor of liquefied petroleum gas cargo (called cargo tank gassing-up operation). For this purpose a thermodynamic model was created which considers two extreme cases of this process. The first is ‘piston pushing’ of inert gas using liquefied petroleum gas vapour. The second case is the complete mixing of both gases and removal the mixture from the tank to the atmosphere until desired concentration or amount of liquefied petroleum gas cargo in the tank is reached. On the example of nitrogen as inert gas and ethylene as a cargo, by thermodynamic analysis an attempt was made to determine the technical parameters of the process, i.e., pressure in the tank, temperature, time at which the operation would be carried out in an optimal way, minimizing the loss of cargo used for gassingup. Calculations made it possible to determine the amount of ethylene used to complete the operation and its loss incurred as a result of total mixing of both gases.
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Authors and Affiliations

Agnieszka Wieczorek
1

  1. Gdynia Maritime University, Morska 81–87, 81-225 Gdynia, Poland
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Abstract

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.

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Authors and Affiliations

Ahmed Ramadhan Al-Obaidi
ORCID: ORCID
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Abstract

In Mexico, one of the principal natural resources is oil, however, the activity related to it has generated hydrocarbon spills on agricultural soils. The aim of this study was to evaluate the biodegradability of diesel by means of indigenous bacteria isolated from agricultural soil contaminated with 68 900 mg kg -1 diesel. We examined indigenous bacterial strains in agricultural soils contaminated with diesel from Acatzingo, Puebla, Mexico. We performed a physicochemical soil characterization, and a bacterial population quantification favoring sporulated bacteria of the genera Bacillus and Paenibacillus taken from the study site. Six bacterial strains were isolated. The identification was made based on the 16S rRNA gene and API systems. The tolerance and biodegradation capacity in diesel were determined at 4 000 to 24 000 mg L -1 of diesel. Residual concentrations of diesel were determined by GC-FID. Soil contaminated with diesel alters the concentrations of organic matter, phosphorus and nitrogen. Analysis of soil samples showed heat resistant bacterial populations of 106 cfu g -1 dry soil. Six strains from soil pollution were identified – Pseudomonas stutzeri M1CH1, Bacillus pumilus M1CH1b, Bacillus cereus M1CH10, Bacillus subtilis M1CH15a, and Paenibacillus lautus strains M1CH19 and M1CH27. These bacteria showed different degradation behavior. Bacillus pumilus M1HC1b and Paenibacillus lautus M1CH27 use diesel oil as the sole carbon source. Bacillus pumilus degraded high concentrations of diesel (24 000 mg L -1), while for Paenibacillus lautus it became toxic and the degradation was less.
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Authors and Affiliations

Amparo Mauricio-Gutiérrez
1
Rocío Machorro-Velázquez
2
Teresita Jiménez-Salgado
3
Candelario Vázquez-Crúz
3
María Patricia Sánchez-Alonso
3
Armando Tapia-Hernández
3

  1. CONACYT – Instituto de Ciencias, Posgrado en Ciencias Ambientales, Benemérita Universidad Autónoma de Puebla, Mexico
  2. Facultad de Ciencias Biológicas, Benemérita Universidad Autónoma de Puebla, Mexico
  3. Centro de Investigación en Ciencias Microbiológicas, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Mexico
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Abstract

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.

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Authors and Affiliations

Erik P. Querner
Henry M. Mulder
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Abstract

We consider the real-life problem of planning tasks for teams in a corporation, in conditions of some restrictions. The problem takes into account various constraints, such as for instance flexible working hours, common meeting periods, time set aside for self-learning, lunchtimes and periodic performance of tasks. Additionally, only a part of the team may participate in meetings, and each team member may have their own periodic tasks such as self-development. We propose an algorithm that is an extension of the algorithm dedicated for scheduling on parallel unrelated processors with the makespan criterion. Our approach assumes that each task can be defined by a subset of employees or an entire team. However, each worker is of a different efficiency, so task completion times may differ. Moreover, the tasks are prioritized. The problem is NP-hard. Numerical experiments cover benchmarks with 10 instances of 100 tasks assigned to a 5-person team. For all instances, various algorithms such as branch-and-bound, genetic and tabu search have been tested.
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Authors and Affiliations

Marek Bazan
1 2
Czesław Smutnicki
1
Maciej E. Marchwiany
2

  1. Wroclaw University of Scienceand Technology, Department of Computer Engineering, Wrocław, Poland
  2. JT Weston sp. z o.o. Warszawa, Poland
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Abstract

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.

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Authors and Affiliations

Paulina Legutko-Kobus
ORCID: ORCID
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Abstract

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.

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Authors and Affiliations

Jacek Kluska
Mateusz Ochnio
Paweł Kazimierski
Dariusz Kardaś
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Abstract

The steam turbine blades of low pressure stages are endangerd by the high-cyclic fatigue due to the combined loading of dynamic stresses by the steam time-variant pressure and the pre-stress from centrifugal forces. Therefore, the importance of their experimental dynamic analysis in the design stage is critical. For laboratory tests of the blades, the piezo actuators placed on the blades, unlike electromagnets placed in the stationary space, give a possibility to excite the flexural vibration of the blades within the bladed disk by time continuous forces independently of the rotor revolutions. In addition, the piezo actuators can be also used to control the vibrations of the blade. Therefore, several dynamic experiments of the clamped model blade equipped with PVDF films were performed for the force description of the piezo foils and their behavior as actuators of the blade vibration. The numerical beam models were used for numerical analysis of the vibration suppression effects both by additional parametric excitation and by active damping. The optimal phase shift of piezo actuator voltage supply was ascertained both for amplitude amplification and suppression. The results contribute to the knowledge of the actuation and active damping of blade vibration by the piezo elements
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Authors and Affiliations

Ludĕk Pešek
Ladislav Půst
Vítĕzslav Bula
Jan Cibulka
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Abstract

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).

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Authors and Affiliations

M. Sterna
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Abstract

Na łamach wydawanego w latach 1886–1893 w Winonie „Wiarusa” publikowano w formie krótkich notatek wiadomości o polskich gazetach i czasopismach wydawanych na ziemiach podzielonej Polski. Informowano o pojawiających się nowych wydawnictwach periodycznych, odnotowywano zmiany zachodzące w poszczególnych tytułach, charakteryzowano ich zawartość, pisano o zmianach personalnych w redakcjach. Zajmowano się kwestiami ograniczania wolności słowa.
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Bibliography

1. Bałabuch H., Kontrowersje w łonie władz carskich na tle konfliktu wokół „Gazety Lubelskiej” w latach 1887–1888, „Kwartalnik Historii Prasy Polskiej” 1999, z. 1. s. 27–35. 2. Bukowski A., Derdowski Hieronim, [w:] Słownik biograficzny Pomorza Nadwiślańskiego, t. 1, Gdańsk 1992, s. 320–322. 3. Bukowski A., Działalność literacka i społeczna H. Derdowskiego w Ameryce (1885–1902), Gdańsk 1961. 4. Bukowski A., Regionalizm kaszubski, Poznań 1950. 5. Cieślak T., Sylwetki mazurskie i kaszubskie, Warszawa 1967. 6. Frycie S., „Tydzień” piotrkowski jako czasopismo społeczno‑literackie, „Rocznik Naukowo‑Dydaktyczny Studium Terenowego Krakowskiej WSP w Rzeszowie. Nauki Humanistyczne” 1964, z. 1, s. 37–141. 7. Janke S., Derdowski, Gdańsk 2002. 8. Mańkowski A., Piśmiennictwo polskie na Warmii, „Gazeta Olsztyńska” 1923, nr 97 (5 V). 9. Ramułt S., Statystyka ludności kaszubskiej, Kraków 1899. 10. Szulist W., Kaszubi w Ameryce. Szkice i materiały, Wejherowo 2005.
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Authors and Affiliations

Grażyna Gzella
1
ORCID: ORCID

  1. Uniwersytet Mikołaja Kopernika w Toruniu

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