Search results

Filters

  • Journals
  • Authors
  • Keywords
  • Date
  • Type

Search results

Number of results: 70
items per page: 25 50 75
Sort by:
Download PDF Download RIS Download Bibtex

Abstract

In this paper, the authors present a novel construction of an automatic balancing device applicable to balancing shafts working in a heavily polluted environment. The novelty of the presented system lies in the fact that its utilization requires no changes to be made in the already existing shafts. Also, the system is capable of working during the operation of the balanced shaft, so there is no need to stop it. The propulsion system is based on eddy current braking, therefore no wires need to be used in the device. During the development process of the system, three iterations of the device were created. Each iteration is presented, described, and discussed. The advantages and drawbacks of each version are pointed out and explained thoroughly. The correctness of the design was verified by the created devices that were assembled and fixed on shafts to prove the design assumptions.
Go to article

Bibliography

[1] J. Alsalaet. Dynamic Balancing and Shaft Alignment. College of Engineering – University of Basrah, Iraq, 2015.
[2] G.K. Grim, J.W. Haidler, and B.J. Mitchell. The Basics of Balancing. Balance Technology Inc., 2014.
[3] M. MacCamhaoil. Static and Dynamic Balancing of Rigid Rotors. Brüel & Kjær, 2016.
[4] R. Kelm, D. Pavelek, and W. Kelm. Rotor balancing tutorial. In: 45th Turbomachinery Symposium, pages 1–29, Huston, Texas, USA, Sept.12–15, 2016. doi: 10.21423/R1G59R.
[5] W.C. Foiles and P.E. Allaire. Single plane and multi-plane rotor balancing using only amplitude. In: 7th IFToMM International Conference on Rotor Dynamics, Vienna, Austria, Sept. 25–28, 2006.
[6] L. Li, S. Cao, J. Li, R. Nie, and L. Hou. Review of rotor balancing methods. Machines, 9(5):89, 2021. doi: 10.3390/machines9050089.
[7] Bendix Aviation Corp. Automatic Balancing of Rotating Bodies. Patent GB570170A, 1945.
[8] P. Żak. A survey of automatic balancing methods for shafts in motion. International Journal of Mechanical Engineering and Robotics Research, 9(4):559–564. doi: 10.18178/ijmerr.9.4.559-564.
[9] P. Loetzner, C.P. Hemingray, and C. Maas. Rotatable shaft balancing machine and method with automatic flexible shaft balancing equipment. Patent US20030024309A1, 2003.
[10] L. Capo and I. Goodbar. Device for the automatic static and dynamic balancing of rotating machinery. Patent GB679522A, 1952.
[11] G. Darrieus. Apparatus for automatic balancing of rotating bodies. Patent US2659243A, 1953.
[12] G. Darrieus. Device for automatic balancing of rotating machine parts. Patent US2778243A, 1957.
[13] J. Perdiart. System for automatically balancing a centrifuge in operation. Patent US4919646, 1990.
[14] O.A. Makarov, V.I. Nisenman, V.I. Pryadilov, and J.P. Tsimansky. Device for automatic balancing of grinding wheel. Patent US4905419, 1990.
[15] H. Wu, X. Pan, and H. Gao. Pneumatic liquid on-line automatic balancer of rotor. Patent US20140311281A1, 2014.
[16] P.C. Stein. Permanent automatic rotor balancer for shafts operating above critical speed. Patent US4117742A, 1978.
[17] W.R. Backer. Automatic balancing means. Patent GB957577A, 1962.
[18] K. Unno and K. Sugita. Automatic balancing apparatus for a rotating body. US3776065A, 1973.
[19] H. Kuwajima, H. Kita, H. Hashi, M. Miyamoto, Y. Ueno, T. Inagaki, and K. Matsuoka. Development of balanced-type high shock suspension for 0.85-in hard disk drive. IEEE Transactions on Magnetics, 42(2):255–260, 2006. doi: 10.1109/TMAG.2005.861736.
[20] Gao Jinji and Zhang Peng. Simulative study of automatic balancing of grinding wheel using a continuously-dripping liquid-injection balancing head. In: 2006 6th World Congress on Intelligent Control and Automation, pages 8002-8005, Dalian, China, 2006. doi: 10.1109/WCICA.2006.1713530.
[21] E. Lulay. Apparatus for balancing a rotary member. Patent US5676025A, 1997.
[22] M. Krygier, P. Żak, L. Podsędkowski, P. Wróblewski, and M. Podsędkowski. A novel autonomous balancing system for shafts in motion. 2022 20th International Conference on Mechatronics – Mechatronika (ME), pages 1-4, Pilsen, Czech Republic, 2022, doi: 10.1109/ME54704.2022.9983460.
[23] M. Krygier, P. Żak, and L. Podsedkowski. Numerical analysis of torques generated in a propulsion system using eddy currents phenomenon. 5th International Conference on Robotics Systems and Automation Engineering (RSAE) (RSAE 2023), April 20–22, 2023, online.
Go to article

Authors and Affiliations

Michał Krygier
ORCID: ORCID
Paweł Żak
1
ORCID: ORCID
Leszek Podsędkowski
1
ORCID: ORCID
Piotr Wróblewski
1
ORCID: ORCID
Maciej Podsędkowski
2
ORCID: ORCID

  1. Institute of Machine Tools and Production Engineering, Lodz University of Technology, Lodz, Poland
  2. Institute of Turbomachinery, Lodz University of Technology, Lodz, Poland
Download PDF Download RIS Download Bibtex

Abstract

Energy from different sources is fundamental to the economy of each country. Bearing in mind the limited reserves of non-renewable energy sources and the fact that their production from new deposits is becoming less economically viable, attention is paid to alternative energy sources, particularly those that are readily available or require no substantial financial investment. One possible solution may be to generate hydrogen, which will then be used for heat (energy) production using other methods. At the same time, these processes will be characterized by low emission levels compared to conventional energy sources. In recent years, more and more emphasis has been placed on the use of clean energy from renewable sources. New, more technically and economically efficient technologies are being developed. The energy use worldwide comes mostly from fossil fuel processing. It can be observed that the share of RES in global production is growing every year. At the end of the 1990s, the share of renewable energy sources was at 6–7%. Global trends indicate the increasing demand for renewable energy due to its form. Global hydrogen resources are practically inexhaustible, but the problem is its availability in molecular form. The article analyzed the use of hydrogen as a fuel. The basic problem is the inexpensive and easy extraction of hydrogen from its compounds; attention has been paid to water, which can easily be electrolytically decomposed to produce oxygen and hydrogen. Hydrogen generated by electrolysis can be stored, but due to its physicochemical properties, it is a costly process; therefore, a decision was made that it is better to store it with natural gas or use it for further reaction. In addition, hydrogen can be used as a substrate for binding and converting the increasingly problematic carbon dioxide, thus reducing its content in the atmosphere.
Go to article

Authors and Affiliations

Tomasz Mirowski
Piotr Janusz
Download PDF Download RIS Download Bibtex

Abstract

In recent years, changes have been made in the structure of primary energy use in the European

Union In addition, a reduction in the use of primary energy has also been observed. According to

the forecasts of the International Energy Agency, the European energy market will be subject to

further changes in the perspective of 2040. These may include the reduction of the energy consumption

and the change in the structure of the energy balance as a result pro-ecological activities.

Natural gas will be the only fossil energy carrier whose role in covering the energy demand will not

change. Along with the changes taking place in the European energy market, global changes can

also be observed. The EU Member States will continue to strive to diversify natural gas supplies.

One of the main elements of diversification of natural gas supplies is the use of LNG regasification

terminals. The reasons for that include the increasing production of natural gas, particularly in the

case of unconventional deposits, the ongoing development of liquefaction terminals, and, as a consequence,

an increase in the LNG supply in the global market. The article presents the utilization of

regasification terminals in the EU Member States and plans for the development of LNG terminals.

Europe has the opportunity to import natural gas through LNG terminals. However, until now,

these have been used to a limited extent. This may indicate that in addition to diversification tasks,

terminals can act as a safeguard against interruptions in gas supplies.

Go to article

Authors and Affiliations

Piotr Janusz
Maciej Kaliski
Download PDF Download RIS Download Bibtex

Abstract

Underground spaces having features such as stability, resistance, and being undetected can play a key role in reducing vulnerability by relocating infrastructures and manpower. In recent years, the competitive business environment and limited resources have mostly focused on the importance of project management in order to achieve its objectives. In this research, in order to find the best balance among cost, time, and quality related to construction projects using reinforced concrete in underground structures, a multi-objective mathematical model is proposed. Several executive approaches have been considered for project activities and these approaches are analyzed via several factors. It is assumed that cost, time, and quality of activities in every defined approach can vary between compact and normal values, and the goal is to find the best execution for activities, achieving minimum cost and the maximum quality for the project. To solve the proposed multi-objective model, the genetic algorithm NSGA-II is used.

Go to article

Authors and Affiliations

S.A. Hosseini
A. Akbarpour
H. Ahmadi
B. Aminnejad
Download PDF Download RIS Download Bibtex

Abstract

Compared to other European countries, Poland has scarce drinking water resources and exhibits

significant variation in annual runoff. On the other hand, the geothermal water resources present in sedimentary/structural basins, mostly in the Polish Lowlands and the Podhale geothermal system, not only provide a

valuable source of renewable energy, which is utilized, although only to a limited extent, but can also be used

for many other purposes. The paper presents the results of studies related to the desalination of low dissolved

mineral content geothermal waters from the Bańska IG-1 well using a dual hybrid system based on ultrafiltration and reverse osmosis. The desalination of geothermal waters may be considered a possible solution leading

to the decentralization of drinking water supply. In many cases, using cooled waters for drinking purposes may

be considered an alternative method of disposing of them, in particular for open drain arrangements, i.e. where

cooled water is dumped into surface waters.

Go to article

Authors and Affiliations

B. Tomaszewska
Download PDF Download RIS Download Bibtex

Abstract

The paper presents abilities and advantages following from the use of the harmonicbalance method for analysis of steady state of a multiphase system with switching devices on example of a matrix converter. Switching elements are modelled as resistances with step-wise variable parameters, what allows to describe the converter by a linear infinite set of equations. The analysis in frequency domain is presented on example of the one-periodic control strategy. External systems were also added using the Thevenin method approach. The numerical calculation results of a linear equations set were verified by the variable structure method in a time domain and the numerical convergence was confirmed. Furthermore, the exemplary complex system was analysed using the cascade method and current waveforms were obtained.

Go to article

Authors and Affiliations

Dariusz Borkowski
Tadeusz J. Sobczyk
Download PDF Download RIS Download Bibtex

Abstract

The article is focused onthe energetical balance of a technical system for the conversion of crushed tyres by pyrolysis. Process temperatures were set in the range from 500 to 650°C. Mass input of the material was 30 kg per hour. The aim of the article is to answer the following questions as regards the individual products: Under which process conditions can the highest quality of the individual products related to energy be reached? How does the thermal efficiency of the system change in reaction to various conditions of the process?

On the basis of the experimental measurements and calculations, apart from other things, it was discovered that the pyrolysis liquid reaches the highest energetic value, i.e. 42.7 MJ.kg-1, out of all the individual products of the pyrolysis process. Generated pyrolysis gas disposes of the highest lower calorific value 37.1 MJ.kg-1 and the pyrolysis coke disposes of the maximum 30.9 MJ kg-1. From the energetic balance, the thermal efficiency of the experimental unit under the stated operational modes ranging from about 52 % to 56 % has been estimated. Individual findings are elaborated on detail in the article.

Go to article

Authors and Affiliations

Stanislav Honus
Veronika Sassmanová
Jaroslav Frantík
Przemysław Bukowski
Dagmar Juchelková
Download PDF Download RIS Download Bibtex

Abstract

Balance, thermodynamic and mainly kinetic approaches using methods of process engineering enable to determine conditions under which iron technology can actually work in limiting technological states, at the lowest reachable fuel consumption (reducing factor) and the highest reachable productivity accordingly. Kinetic simulation can be also used for variant prognostic calculations. The paper deals with thermodynamics and kinetics of iron making process. It presents a kinetic model of iron oxide reduction in a low temperature area. In the experimental part it deals with testing of iron ore feedstock properties. The theoretical and practical limits determined by heat conditions, feedstock reducibility and kinetics of processes are calculated.

Go to article

Authors and Affiliations

Pavlína Pustějovská
Simona Jursová
Download PDF Download RIS Download Bibtex

Abstract

Many precision devices, especially measuring devices, must maintain their technical parameters in variable ambient conditions, particularly at varying temperatures. Examples of such devices may be super precise balances that must keep stability and accuracy of the readings in varying ambient temperatures. Due to that fact, there is a problem of measuring the impact of temperature changes, mainly on geometrical dimensions of fundamental constructional elements of these devices. In the paper a new system for measuring micro-displacements of chosen points of a constructional element of balance with a resolution of single nanometres and accuracy at a level of fractions of micrometres has been proposed.

Go to article

Authors and Affiliations

Marek Dobosz
Adam Woźniak
Mariusz Kożuchowski
Marek Ściuba
Olga Iwasińska-Kowalska
Download PDF Download RIS Download Bibtex

Abstract

The aim of this work is to design the links‒spring mechanism for balancing, in the three positions of the operating range, a rotary disc subjected to a torque. An energy-related approach towards the conditions of the mechanical system balance for a discrete number of positions leads to the formulation of a task of searching for a four-bar linkage which guides a coupler point through the prescribed positions, where, at the same time, geometrical conditions (specifying the spring tension) and kinematic conditions (defining the radial component of the tension change rate) are satisfied. The finitely and infinitesimally separated position synthesis is considered, however, only a component of the coupler point velocity is essential. A general method was proposed for determining the four-bar mechanism geometry. Mechanism inversion was applied in order to reduce the number of designed variables and simplify the solution method. The system of complex algebraic equations defines the problem. Linear, symbolic transformations and a systematic search technique are utilized to find multiple local optimal solutions. The problem is solved using Mathematica software.
Go to article

Bibliography

[1] V.H. Arakelian and S. Briot. Balancing of Linkages and Robot Manipulators. Advanced Methods with Illustrative Examples. Springer, 2015.
[2] P. Wang and Q. Xu. Design and modeling of constant-force mechanisms: A survey. Mechanism and Machine Theory, 119:1–21, 2018. doi: 10.1016/j.mechmachtheory.2017.08.017.
[3] V. Arakelian and M. Mkrtchyan. Design of scotch yoke mechanisms with balanced input torque. In Proceedings of the ASME 2015 International Design Engineering Technical Conferences \amp Computers and Information in Engineering Conference IDETC/CIE 2015, pages 1–5, Boston, Massachusetts, USA, 2–5 August, 2015. doi: 10.1115/DETC2015-46709.
[4] J.A. Franco, J.A. Gallego, and J.L. Herder. Static balancing of four-bar compliant mechanisms with torsion springs by exerting negative stiffness using linear spring at the instant center of rotation. Journal of Mechanisms and Robotics, 13(3):031010–13, 2021. doi: 10.1115/1.4050313.
[5] B. Demeulenaere and J. De Schutter. Input torque balancing using an inverted cam mechanism. Journal of Mechanical Design, 127(5):887–900, 2005. doi: 10.1115/1.1876452.
[6] D.A. Streit and E. Shin. Equilibrators for planar linkages. Journal of Mechanical Design, 115(3):604–611, 1993. doi: 10.1115/1.2919233.
[7] Y. Liu, D.P. Yu, and J. Yao. Design of an adjustable cam based constant force mechanism. Mechanism and Machine Theory, 103:85–97, 2016. doi: 10.1016/j.mechmachtheory.2016.04.014.
[8] J.L. Herder. Design of spring force compensation systems. Mechanism and Machine Theory, 33(1-2):151–161, 1998. doi: 10.1016/S0094-114X(97)00027-X.
[9] S.R. Deepak and G.K. Ananthasuresh. Static balancing of a four-bar linkage and its cognates. Mechanism and Machine Theory, 4:62–80, 2012. doi: 10.1016/j.mechmachtheory.2011.09.009.
[10] S. Perreault, P. Cardou, and C. Gosselin. Approximate static balancing of a planar parallel cable-driven mechanism based on four-bar linkages and springs. Mechanism and Machine Theory, 79:64–79, 2014. doi: 10.1016/j.mechmachtheory.2014.04.008.
[11] J. Buśkiewicz. The optimum distance function method and its application to the synthesis of a gravity balanced hoist. Mechanism and Machine Theory, 139:443–459, 2019. doi: 10.1016/j.mechmachtheory.2019.05.006.
[12] V.L. Nguyen. A design approach for gravity compensators using planar four-bar mechanisms and a linear spring. Mechanism and Machine Theory, 172:104770, 2022. doi: 10.1016/j.mechmachtheory.2022.104770.
[13] R. Barents, M. Schenk, W.D. van Dorsser, B.M. Wisse, and J.L. Herder. Spring-to-spring balancing as energy-free adjustment method in gravity equilibrators. Journal of Mechanical Design, 133(6):689–700, 2011. doi: 10.1115/DETC2009-86770.
[14] I. Simionescu and L. Ciupitu. The static balancing of the industrial robot arms, Part I: discrete balancing. Mechanism and Machine Theory, 35(9):1287–1298, 2001. doi: 10.1016/S0094-114X(99)00067-1.
[15] A.G. Erdman and G.N. Sandor. Mechanism Design: Analysis and Synthesis, Vol. 1, 4th ed., Prentice-Hall, Upper Saddle River, NJ, 2001.
[16] G.N. Sandor and A.G. Erdman. Advanced Mechanism Design: Analysis and Synthesis, Vol. 2, Prentice Hall, Englewood Cliffs, NJ, 1997.
[17] J.M. McCarthy and G.S. Soh. Geometric Design of Linkages, Vol. 11, Springer, New York, 2011.
[18] H. Kaustubh, J. Sonawale, and J.M. McCarthy. A design system for six-bar linkages integrated with a solid modeler. Journal of Computing and Information Science in Engineering, 15(4):041002, 2015. doi: 10.1115/1.4030940.
[19] J. Han and W. Liu. On the solution of eight-precision-point path synthesis of planar four-bar mechanisms based on the solution region methodology. Journal of Mechanisms and Robotics, 11(6):064504, 2019. doi: 10.1115/1.4044544.
[20] C.W. Wampler, A.P. Morgan, and A.J. Sommese. Complete solution of the nine-point path synthesis problem for four-bar linkages. Journal of Mechanical Design, 114(1):153–159, 1992. doi: 10.1115/1.2916909.
[21] W. Guo and X. Wang. Planar linkage mechanism design for bi-objective of trajectory and velocity. J Beijing Univ Aero Astronautics, 35(12):1483–1486, 2009.
[22] J. Han, W. Qian, and H. Zhao. Study on synthesis method of $\lambda$-formed 4-bar linkages approximating a straight line. Mechanism and Machine Theory, 44(1):57–65, 2009. doi: 10.1016/j.mechmachtheory.2008.02.011.
[23] J.E. Holte, T.R. Chase, and A.G. Erdman. Approximate velocities in mixed exact-approximate position synthesis of planar mechanisms. Journal of Mechanical Design, 123(3):388–394, 2001. doi: 10.1115/1.1370978.
[24] W.T. Lee and K. Russell. Developments in quantitative dimensional synthesis (1970–present): Four-bar path and function generation. Inverse Problems in Science and Engineering, 26(9):1280–1304, 2017. doi: 10.1080/17415977.2017.1396328.
[25] C. Wampler and A. Sommese, Numerical algebraic geometry and algebraic kinematics. Acta Numerica, 20:469–567, 2011. doi: 10.1017/S0962492911000067.
[26] D.A. Brake, J.D. Hauenstein, A.P. Murray, D.H. Myszka, and C.W. Wampler. The complete solution of alt-burmester synthesis problems for four-bar linkages. Journal of Mechanisms and Robotics, 8(4): 041018, 2016. doi: 10.1115/1.4033251.
[27] J. Buśkiewicz, 2019, Gravity balancing of a hoist by means of a four-bar linkage and spring. In: Advances in Mechanism and Machine Science: Proceedings of the 15th IFToMM World Congress on Mechanism and Machine Science, pages 1721–1730, Cracow, Poland, June, 2019. doi: 10.1007/978-3-030-20131-9_170.
[28] J. Buśkiewicz. Solution data, the code of algorithm 6dv2s_II in Mathematica wolfram 8.0 and pdf file of the code, the figures of the spring extensions and the rates of the spring extensions for all the cases. Mendeley Data, V3, 2022, https://data.mendeley.com/datasets/sb38dsw6vm/3.
Go to article

Authors and Affiliations

Jacek Buśkiewicz
1
ORCID: ORCID

  1. Poznan University of Technology, Poznan, Poland
Download PDF Download RIS Download Bibtex

Abstract

Traditional mass balance measurements by stake readings and snow surveying have been conducted annually since 1996 on the Waldemar Glacier (= Waldemarbreen) in northwest Spitsbergen, Svalbard. Several indirect methods were also used for estimating its mass balance. These methods were divided into two major groups: climatological and geodetic. A comparison of the latest map (2000) with that of 1978 and climatological records enable us to calculate the change in the mass balance of Waldemarbreen over 34 years. These methods include air temperature and degree-day (PDD) models. The average mass balance of Waldemarbreen, computed by climatological methods, was -0.42 m a-1 of water equivalent (w.e.) for the period 1970-2004, and -0.51 m w.e. for 1996-2004. These balances were compared with the glaciological balance for the period 1996-2004, -0.53 m w.e.. The mass balance was also computed using geodetic method, giving -0.52 m of w.e. from 1978 to 2000. It is suggested that, from these results, the approach used for Waldemarbreen might be also useful for estimation the mass balances of other small Svalbard glaciers which terminate on land.

Go to article

Authors and Affiliations

Ireneusz Sobota
Download PDF Download RIS Download Bibtex

Abstract

The paper discusses the water resources of the Krężniczanka River catchment. The catchment with an area of 224.9 km2 is located south-west of Lublin. The characteristics of the groundwaters and runoff were determined based on hydrological and hydrogeological materials of the Department of Hydrology of the Maria Curie-Skłodowska University (UMCS). Mean runoff in the period from 2010 to 2016 amounted to 125.7 mm, precipitation 629.4 mm, and evapotranspi-ration 503.7 mm. A strong relationship was determined between the rhythm of runoff and ground-water level fluctuations. The contribution of groundwater supply in total runoff equalled 81.5%.
Go to article

Authors and Affiliations

Zdzisław Michalczyk
Stanisław Chmiel
Sławomir Głowacki
Joanna Sposób
Beata Zielińska
Download PDF Download RIS Download Bibtex

Abstract

The paper investigates a significant influence of transients on steady states in a matrix converter with the one-periodic control strategy. Proposed controller can be used as an interconnection device within a power system for a power flow control. However, the presence of inductances in external systems has the significant influence on steady state of a matrix converter operation. The special current injection method has been developed to ensure a proper operation of a matrix converter. Presented analysis of steady states is carried out in a frequency domain using the harmonic balance method. Obtained numerical results, which are confirmed by a time domain analysis, prove the effectiveness of the proposed method.
Go to article

Authors and Affiliations

Dariusz Borkowski
Tadeusz Sobczyk
Download PDF Download RIS Download Bibtex

Abstract

The main topic of this study is the mathematical modelling of bubble size distributions in an aerated stirred tank using the population balance method. The air-water system consisted of a fully baffled vessel with a diameter of 0.29 m, which was equipped with a six-bladed Rushton turbine. The secondary phase was introduced through a ring sparger situated under the impeller. Calculations were performed with the CFD software CFX 14.5. The turbulent quantities were predicted using the standard k-ε turbulence model. Coalescence and breakup of bubbles were modelled using the MUSIG method with 24 bubble size groups. For the bubble size distribution modelling, the breakup model by Luo and Svendsen (1996) typically has been used in the past. However, this breakup model was thoroughly reviewed and its practical applicability was questioned. Therefore, three different breakup models by Martínez-Bazán et al. (1999a, b), Lehr et al. (2002) and Alopaeus et al. (2002) were implemented in the CFD solver and applied to the system. The resulting Sauter mean diameters and local bubble size distributions were compared with experimental data.

Go to article

Authors and Affiliations

Zbyněk Kálal
Milan Jahoda
Ivan Fořt
Download PDF Download RIS Download Bibtex

Abstract

In many systems of engineering interest the moment transformation of population balance is applied. One of the methods to solve the transformed population balance equations is the quadrature method of moments. It is based on the approximation of the density function in the source term by the Gaussian quadrature so that it preserves the moments of the original distribution. In this work we propose another method to be applied to the multivariate population problem in chemical engineering, namely a Gaussian cubature (GC) technique that applies linear programming for the approximation of the multivariate distribution. Examples of the application of the Gaussian cubature (GC) are presented for four processes typical for chemical engineering applications. The first and second ones are devoted to crystallization modeling with direction-dependent two-dimensional and three-dimensional growth rates, the third one represents drop dispersion accompanied by mass transfer in liquid-liquid dispersions and finally the fourth case regards the aggregation and sintering of particle populations.

Go to article

Authors and Affiliations

Jerzy Bałdyga
Grzegorz Tyl
Mounir Bouaifi
Download PDF Download RIS Download Bibtex

Abstract

The work is a part of research into the reduction of energy consumption in the production of EPSthrough the modernization

of technological equipment used. This paper presents the results of research and analysis of heat transfer process between the water vapor

that was provided to machine, the mold, the product and the environment. The paper shows the calculation of the heat balance of the

production cycle for two types of mold: standard and modernized. The performance tests used an infrared imaging camera.

The results were used to develop a computer image analysis and statistical analysis. This paper presents the main stages of the production

process and the construction of technological equipment used, changing the mold surface temperature field during the production cycle

and the structure of the heat balance for the mold and its instrumentation. It has been shown that the modernization of construction

of technological equipment has reduced the temperature field and as a consequence of decreased of demand for process steam production

cycle.

Go to article

Authors and Affiliations

R. Władysiak
T. Pacyniak
W. Bogus
Download PDF Download RIS Download Bibtex

Abstract

Lysimeters represent the ideal tool for direct measurement of soil water balance components in soil profiles. Changes in the water content in a soil monolith can be measured with sufficient accuracy by the precise lysimeter weighing system.Water content changes in soil monolith as derived from lysimeter mass represent one of the basic water balance compo-nent. This paper deals with the development and comparison of individual soil water balance components in two different soil profiles from the Easter-Slovakian-Lowland. Two lysimeter vessels were filled monolithically with two different soil profiles covered with grass: one sandy soil profile from locality Poľany and one silty-loam soil profile from locality Vysoká nad Uhom. A constant groundwater level of 1 m below ground level was maintained in both soil profiles. Under the same meteorological conditions, all differences in the development of water balance components were caused only by the differences in soil profiles. The actual evapotranspiration and water flows at the bottom of the soil profiles were compared. Sandy soils are generally considered to be more prone to drought than silty-loam soils. Under the specific conditions of this experiment (maintaining a constant groundwater level) the opposite was shown, when the silty-loam soil profile was more prone to drought than sandy soil profile. Sandy soilprofile from Poľany reacted more quickly to precipitation (or evaporation). Due to the higher hydraulic conductivity of the sandy soil compared to the silty-loamy soil, the groundwater level response to external stimuli was much faster.

Go to article

Authors and Affiliations

Andrej Tall
Dana Pavelková
Download PDF Download RIS Download Bibtex

Abstract

Permanent grasslands – according to the Water Framework Directive – are typical water related ecosystems so they largely affect water quality, its cycling and balance and therefore deserve protection. They are an element of landscape structure (ecosystem function or service) commonly considered a factor stabilising environmental changes.

Most threats posed to waters in Poland originate from present cropland structure with its definite predominance of arable lands over grasslands. Agriculture should therefore focus on the improvement of land use structure in order to minimise environmental hazards and to guarantee at the same time optimum economic effects. This could be achieved by turning arable lands into grasslands (where justified e.g. on light soils) or at least by maintaining present grassland area (condition in negotiations with the EU) and management that would consider environmental protection.

Increasing the contribution of grasslands to cropland structure or at least maintaining their pre-sent status quo would help to achieve compromise between the goals of farmers and environmental protection. Purposeful utilisation of ecosystem services, particularly those of grasslands, allows to maintain more intensive farming without environmental hazard. Limited should be only such activi-ties whose intensity exceeds regenerative or buffering environmental capacity e.g. on grounds par-ticularly subjected to water pollution or those included into Natura 2000 network.

Go to article

Authors and Affiliations

Halina Jankowska-Huflejt
Download PDF Download RIS Download Bibtex

Abstract

Wetlands play a significant role in agricultural landscape. They are the areas of exception-ally great natural values able to regulate water cycling in river catchments. In many cases they are the basic food source for bred animals.

Large areas of wetlands (c. 4 million ha) have been drained for agricultural purposes in Poland. Nevertheless, there are still numerous natural (or close to natural) wetlands, part of which is protected in nature reserves or national parks.

Having in mind the transformation of agriculture and the need of protecting water resources and natural environment, it is necessary to regulate the principles of utilisation and management of re-claimed wetlands. Water management should be adjusted to the type of an area and to environmental requirements. Regardless of the type and intensity of agricultural use of wetlands one has to aim at limiting rapid outflow of spring thaw and rainfall waters which means the reconstruction and increas-ing of natural retention capacity of the river catchment. It is necessary to provide an appropriate num-ber of water lifting facilities and their proper exploitation in land reclamation objects.

It is as well necessary to create appropriate organizational, legal and financial conditions stimu-lating actions to improve water balance and wetland protection.

Go to article

Authors and Affiliations

Waldemar Mioduszewski
Download PDF Download RIS Download Bibtex

Abstract

The Kibble balance experiment is used to redefine the kilogram as a unit of mass based on the Planck constant. To demonstrate and understand the basic principle of the Kibble balance, the National Institute of Standards (NIS)-Egypt has constructed a prototype Kibble balance that can measure gram-level masses with 0.01% relative uncertainty. Through the construction of this prototype, the challenges can be studied and addressed to overcome the weaknesses of NIS’s prototype. This study presents the design and construction of the prototype Kibble balance. It also focuses on the design and performance of the magnetic system, which is a crucial element of the Kibble balance. Analytical modeling and finite element analysis were used to evaluate and improve the magnet system. Several other aspects were also discussed, including the yoke’s material and enhancing the magnetic profile within the air gap of the magnet system. Over a vertical distance of 30 mm inside the air gap, the magnetic flux density was found to be 0.3 T, and the uniformity was found to be 8 x 10 -5.
Go to article

Authors and Affiliations

Sayed Emira
1
E.R. Shaaban
2
M.M. Rashad
3
Shaker A. Gelany
1

  1. National Institute of Standards (NIS), Tersa St, El-Haram, PO Box 136, Code 12211, Giza, Egypt
  2. Department of Physics, Faculty of Science, Al-Azhar University, Assiut 71542, Egypt
  3. Central Metallurgical Research and Development Institute (CMRDI), P.O. BOX. 87 Helwan, Egypt 11421
Download PDF Download RIS Download Bibtex

Abstract

This paper gives the results of investigations carried out in the Fugleberget basin which lies on the northern shore of the Hornsund Fiord, in the unglaciated region of raised sea terraces and on the slopes of the Fugleberget (569 m a.s.l.) and the Ariekammen (511 m a.s.l.). The investigations were carried out between 23 July, 1979 and 4 September, 1980, including the polar night. The Fugleberget basin represents well the area of sea terraces and coastal mountains uncovered with glacier and occupying large areas in West Spitsbergen. These areas are characterized by the presence of permafrost. The aim of investigations was to determine such fluvial processes as the duration of the hydrological period, the manner of water supply to the basin and an attempt to define the elements of the water balance. In addition studies were made on hydrological processes, particulary changes in the chemical composition of water, and the magnitude of denudation determined.

Go to article

Authors and Affiliations

Marian Pulina
Wiesława Krawczyk
Jerzy Pereyma
Download PDF Download RIS Download Bibtex

Abstract

This paper contains thsults of hydrological and hydrochemical investigations carried out in the basin of Werenskiöld Glacier against the background of determining climate elements. It also gives chosen elements of the water balance and mass balance determined from year-long investigations of the polar hydrological year 1979-1980.

Go to article

Authors and Affiliations

Marian Pulina
Jerzy Pereyma
Janusz Kida
Wiesława Krawczyk

This page uses 'cookies'. Learn more