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Number of results: 16
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Abstract

During the cruise of the research ship r/v Oceania owned by the Institute of Oceanology of the Polish Academy of Sciences in Sopot a research on mineral suspension concentration and dispersion distributions was conducted. The research area included the western part of the Baltic Sea, the Danish Straits, the Norwegian Sea, the waters around Spitsbergen and the North Atlantic Ocean. Samples of water were collected from the surface layer. They were subjected to microscopic analysis. Measurements were done with a projection microscope (magnification lOOOx) and using the Burker's table. After counting the particles dispersion distribution was determined. The largest concentration of mineral suspension was noted offshore in the Norwegian Sea and around Spitsbergen and the smallest in the central Atlantic Ocean.
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Abstract

Concentration and dispersion distributions of mineral suspension and crude-oil particles in waters of the Kongsfiord (Spitsbergen) were examined in 1997. Most suspension occurs at glacier margins and decreases towards a fiord outlet.
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Abstract

Discusses an attempt to optimize the operation of an electric furnace slag to be decopperisation suspension of the internal recycling process for the production of copper. The paper presents a new method to recover copper from metallurgical slags in arc-resistance electric furnace. It involves the use of alternating current for a first period reduction, constant or pulsed DC in the final stage of processing. Even distribution of the electric field density in the final phase of melting caused to achieve an extremely low content of metallic copper in the slag phase. They achieved by including the economic effects by reducing the time reduction.
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Abstract

The paper describes the design and multibody dynamic analysis of a mechanically interconnected suspension, as applied to a small off-road vehicle. Interconnected suspensions use some sort of connection between the axles of a vehicle in order improve ride quality or vehicle handling. In principle, the connection may be hydraulic, pneumatic, or mechanical, but for installation in a typical passenger car, a mechanical connection would likely be impractical due to weight and complexity. In this paper, the vehicle in question is the University of Windsor SAE Baja off-road competition vehicle, and novel mechanical design is proposed. A multibody dynamic analysis is performed on the proposed design using the EoM open source multibody software developed by theUniversity ofWindsorVehicle Dynamics and Control research group in order to assess any potential performance improvements.
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Abstract

The paper focuses on the influence of the longitudinal and lateral suspension damping in correlation with the velocity upon the vibration behaviour of the railway vehicles while moving on a tangent track. The numerical simulations are developed based on a linear model of a 17-degree of freedom vehicle that allows the evaluation of the dynamic behaviour of the vehicle in a sub-critical velocity. Based on the response frequency functions of the vehicle in a harmonic and in a random behaviour, a series of basic properties of the stable behaviour of the forced lateral vibrations has been made evident, as well as the opportunities to lower the level of the carbody vibrations by changing the suspension damping.
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Abstract

The paper focuses on a nonlinear model to represent the mechanical behaviour of a mix coil spring – rubber used in the secondary suspension of passenger rail vehicles. The principle of the model relies on overlapping of the forces corresponding to three components – the elastic component, the viscous component and the dry friction component. The model has two sources on non-linearity, in the elastic force and the friction force, respectively. The main attributes of the model are made visible by its response to an imposed displacement-type harmonic excitation. The results thus obtained from the applications of numerical simulation show a series of basic properties of the model, namely the dependence on amplitude and the excitation frequency of the model response, as well as of its stiffness and damping.
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Abstract

This paper focuses on the design and control of an active suspension system, where a tubular linear motor is integrated into a spring damper system of a vehicle. The spring takes up the weight of the vehicle. Therefore the electric linear motor can be designed very compact as it has to provide forces to adjust the damping characteristic only. Design and construction of the active suspension system, a control strategy and validation measurements at a test bench are presented.
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Abstract

The Bulletin of the Polish Academy of Sciences: Technical Sciences (Bull.Pol. Ac.: Tech.) is published bimonthly by the Division IV Engineering Sciences of the Polish Academy of Sciences, since the beginning of the existence of the PAS in 1952. The journal is peer‐reviewed and is published both in printed and electronic form. It is established for the publication of original high quality papers from multidisciplinary Engineering sciences with the following topics preferred: Artificial and Computational Intelligence, Biomedical Engineering and Biotechnology, Civil Engineering, Control, Informatics and Robotics, Electronics, Telecommunication and Optoelectronics, Mechanical and Aeronautical Engineering, Thermodynamics, Material Science and Nanotechnology, Power Systems and Power Electronics. Journal Metrics: JCR Impact Factor 2018: 1.361, 5 Year Impact Factor: 1.323, SCImago Journal Rank (SJR) 2017: 0.319, Source Normalized Impact per Paper (SNIP) 2017: 1.005, CiteScore 2017: 1.27, The Polish Ministry of Science and Higher Education 2017: 25 points. Abbreviations/Acronym: Journal citation: Bull. Pol. Ac.: Tech., ISO: Bull. Pol. Acad. Sci.-Tech. Sci., JCR Abbrev: B POL ACAD SCI-TECH Acronym in the Editorial System: BPASTS.
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Abstract

Combustion technology of the coal-water suspension creates a number of new possibilities to organize the combustion process fulfilling contemporary requirements, e.g. in the environment protection. Therefore the in-depth analysis is necessary to examine the technical application of coal as a fuel in the form of suspension. The research undertakes the complex investigations of the continuous coal-water suspension as well as cyclic combustion. The cyclic nature of fuel combustion results from the movement of the loose material in the flow contour of the circulating fluidized bed (CFB): combustion chamber, cyclone and downcomer. The experimental results proved that the cyclic change of oxygen concentration around fuel, led to the vital change of both combustion mechanisms and combustion kinetics. The mathematical model of the process of fuel combustion has been presented. Its original concept is based on the allowance for cyclic changes of concentrations of oxygen around the fuel. It enables the prognosis for change of the surface and the centre temperatures as well as mass loss of the fuel during combustion in air, in the fluidized bed and during the cyclic combustion.
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Abstract

The purpose of this work is to find a correlation for heat transfer to walls in a 1296 t/h supercritical circulating fluidised bed (CFB) boiler. The effect of bed-to-wall heat transfer coefficient in a long active heat transfer surface was discussed, excluding the radiation component. Experiments for four different unit loads (i.e. 100% MCR, 80% MCR, 60% MCR and 40% MCR) were conducted at a constant excess air ratio and high level of bed pressure (ca. 6 kPa) in each test run. The empirical correlation of the heat transfer coefficient in a large-scale CFB boiler was mainly determined by two key operating parameters, suspension density and bed temperature. Furthermore, data processing was used in order to develop empirical correlation ranges between 3.05 to 5.35 m·s-1 for gas superficial velocity, 0.25 to 0.51 for the ratio of the secondary to the primary air, 1028 to 1137K for bed temperature inside the furnace chamber of a commercial CFB boiler, and 1.20 to 553 kg·m-3 for suspension density. The suspension density was specified on the base of pressure measurements inside the boiler’s combustion chamber using pressure sensors. Pressure measurements were collected at the measuring ports situated on the front wall of the combustion chamber. The obtained correlation of the heat transfer coefficient is in agreement with the data obtained from typical industrial CFB boilers.
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Abstract

Experimental research has been carried out in a supercritical circulating fluidized bed combustor in order to indicate the effect of the bed particle size on bed-to-wall heat transfer coefficient. The bed inventory used were 0.219, 0.246 and 0.411 mm Sauter mean particles diameter. The operating parameters of a circulating fluidized bed combustor covered a range from 3.13 to 5.11 m/s for superficial gas velocity, 23.7 to 26.2 kg/(m2s) for the circulation rate of solids, 0.33 for the secondary air fraction and 7500 to 8440 Pa pressure drop. Furthermore, the bed temperature, suspension density and the main parameters of cluster renewal approach were treated as experimental variables along the furnace height. The cluster renewal approach was used in order to predict the bed-to-wall heat transfer coefficient. A simple semi-empirical method was proposed to estimate the overall heat transfer coefficient inside the furnace as a function of particle size and suspension density. The computationally obtained results were compared with the experimental data of this work.
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Abstract

The paper presents optimization of 5-rod (5-link) suspension mechanism used in passenger cars for independent guiding of the wheels. Selected stiffness coefficients defined for five elastomeric bushings installed in joints of the suspension rods are considered as design variables. Two models with lumped parameters (i.e. elastokinematic and dynamic) of wheel-suspension-car body system are formulated to describe relationships between the design variables and the performance indexes including car active safety and ride comfort, respectively. The multi-criteria goal function is minimized using a deterministic algorithm. The suspension with optimized bushings rates fulfils desired elastokinematic criteria together with a defined dynamic criterion, describing the so-called rolling comfort. An event of car passing over short road bump is considered as dynamic conditions. The numerical example deals with an actual middle-class passenger car with 5-rod suspension at the front driven axle. Estimation of the models parameters and their verification were carried out on the basis of indoor and outdoor experiments. The proposed optimization procedure can be used to improve the suspension design or development cycle.
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Abstract

The suspension of copper droplets in the slag is considered. The copper/slug suspension is delivered as the product from the direct-toblister process which is applied in the KGHM – Polska Miedź (Polish Copper) S.A. factory. The droplets / slag suspension was treated by a special set of reagents (patented by the authors) to improve the coagulation process. On the other hand, the observations are made to estimate if the melting / reduction process in the furnace is sufficiently effective to avoid a remaining of carbon in the copper droplets. The coagulation process was carried out in the crucible (laboratory scale). However, conditions imposed to the coagulation / solidification process in the laboratory scale were to some extent similar to those applied usually in the industry when the suspension is subjected to the analogous treatment in the electric arc-furnace. Some suggestions are formulated how to improve the industrial direct-to-blister process.
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Abstract

The analysis of particle size in suspensions carried out with use of the laser diffraction method enables us to obtain not only information about the size of particles, but also about their properties, shape and spatial structure, determined basing on fractal dimension. The fractal dimension permits the evaluation of the interior of aggregates, at the same time showing the degree of complexity of the matter. In literature, much attention is paid to the evaluation of the fractal dimension of flocs in activated sludge, in the aspect of control of single processes, i.e. sedimentation, dehydration, coagulation or flocculation. However, results of research concerning the size of particles and the structure of suspensions existing in raw and treated sewage are still lacking. The study presents optical fractal dimensions D3 and particle size distributions measured with use of laser granulometer in raw and treated sewage and activated sludge collected from six mechanical-biological wastewater treatment plants located in the Lower Silesian region. The obtained test results demonstrate that wastewater treatment plants that use both sequencing batch reactors and continuous flow reactors are more efficient at capturing suspension particles of a size up to 30 μm and are characterized by an increased removal of particles of a size ranging from 30 μm to 550 μm to the outflow. Additionally, in the case of samples of treated sewage and activated sludge collected at the same location, at short intervals, similar particle distributions were observed. As far as the analysis of fractal dimensions is concerned, particles contained in the raw sewage suspension were characterized by the lowest values of the fractal dimension (median equals 1.89), while the highest values occurred in particles of activated sludge (median equals 2.18). This proves that the spatial structure of suspension particles contained in raw sewage was similar to a linear structure, with a large amount of open spaces, while the structure of particles contained in the activated sludge suspension was significantly more complex in the spatial aspect.
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