Research in termoacoustics began with the observation of the heat transfer between gas and solids. Using this interaction the intense sound wave could be applied to create engines and heat pumps. The most important part of thermoacoustic devices is a regenerator, where press of conversion of sound energy into thermal or vice versa takes place. In a heat pump the acoustic wave produces the temperature difference at the two ends of the regenerator. The aim of the paper is to find the influence of the material used for the construction of a regenerator on the properties of a thermoacoustic heat pump. Modern technologies allow us to create new materials with physical properties necessary to increase the temperature gradient on the heat exchangers. The aim of this paper is to create a regenerator which strongly improves the efficiency of the heat pump.

There are two basic types of coal mine gases: gas from demethanation of coal deposits, and ventilation gas; containing combustible ingredients (mainly methane, CH4). Effective use of these gases is an important technical and ecological issue (greenhouse gas emissions), mainly due to the presence of methane in these gases. Serious difficulties in this area (e.g. using them as the fuel for internal combustion (IC) engine) occur mainly in relation to the ventilation gas, whereas the gas from demethanation of coal deposits can be used directly as the fuel for internal combustion engines. The proposed solution of this problem shows that the simple mixing of these two gases (without supplying of oxygen from ambient air) is the effective way to producing the gaseous combustible mixture, which can be used for the fueling of internal combustion gas engines. To evaluate the energy usefulness of this way produced combustible mixture the process indicator has been proposed, which expresses the share of the chemical energy supplied with the ventilation gas, in the whole chemical energy of the produced fuel combustible mixture. It was also established how (e.g., by appropriate choice of the mixed gas streams) can be achieved significantly higher values of the characteristic process indicator, while retaining full energy usefulness of the gained gaseous mixture to power combustion engines.

The motion of a ring pack on a thin film covering a cylinder liner has been analysed. In contrast to the previous papers [30], [31], which considered a primary hydrodynamic phenomena (including mixed lubrication), in the present paper an additional degree of freedom of a ring i.e. a twist motion is also taken into account. Equations describing the twist of rings are presented and used in simulation. The twist phenomena of a single ring have been analysed in the past [25]. In this paper, the twist effects of separate rings forming a ring pack are considered. In the pack configuration, the twist of the upstream ring strongly influences the operation of the downstream ring. The phenomenon commonly treated as secondary effect seems to be influencing the ring motion strongly. Differences between results obtained applying and neglecting ring twist motion are analysed and discussed.

It has been found that the vegetable oils are promising substitute, because of their properties are similar to those of diesel fuel and they are renewable and can be easily produced. However, drawbacks associated with crude vegetable oils are high viscosity, low volatility call for low heat rejection combustion chamber, with its significance characteristics of higher operating temperature, maximum heat release, and ability to handle lower calorific value (CV) fuel etc. Experiments were carried out to evaluate the performance of an engine consisting of different low heat rejection (LHR) combustion chambers such as ceramic coated cylinder head-LHR-1, air gap insulated piston with superni (an alloy of nickel) crown and air gap insulated liner with superni insert - LHR-2; and ceramic coated cylinder head, air gap insulated piston and air gap insulated liner - LHR-3 with normal temperature condition of crude rice bran oil (CRBO) with varied injector opening pressure. Performance parameters (brake thermal efficiency, brake specific energy consumption, exhaust gas temperature, coolant load, and volumetric efficiency) and exhaust emissions [smoke levels and oxides of nitrogen [NOx]] were determined at various values of brake mean effective pressure of the engine. Combustion characteristics [peak pressure, time of occurrence of peak pressure, maximum rate of pressure rise] were determined at full load operation of the engine.

Conventional engine (CE) showed compatible performance and LHR combustion chambers showed improved performance at recommended injection timing of 27°bTDC and recommend injector opening pressure of 190 bar with CRBO operation, when compared with CE with pure diesel operation. Peak brake thermal efficiencyincreased relatively by 7%, brake specific energy consumption at full load operation decreased relatively by 3.5%, smoke levels at full load decreased relatively by 11% and NOx levels increased relatively by 58% with LHR-3 combustion chamber with CRBO at an injector opening pressure of 190 bar when compared with pure diesel operation on CE.

The article concerns computer modelling of processes in cooling systems of internal combustion engines. Modelling objectives and existing commercial programs are presented. It also describes Author’s own method of binding graphs used to describe phenomena in the cooling system of a spark ignition engine. The own model has been verified by tests on the engine dynamometer. An example of using a commercial program for experimental modelling of an installation containing a heat accumulator is presented.

Replacing silicon with diamond may significantly reduce energy losses in electronic devices, according to Dr. Michał Pomorski from the CEA-LIST Diamond Sensors Laboratory in France.

In the paper, the Author presents the method of realisation of various scenarios of "test ride" on engine test bench. Research possibilities offered by semi-virtual system consisting of a real engine and a vehicle simulator are described. The previous article by the Author, "The Principles of Engine Operation Simulation in Test-bench Examination in the Conditions Equivalent to Traffic Exploitation of the Vehicle" [7] was devoted to the description of test requirements. Test accuracy, structure and equipment of the test stand were described there, as well as the characteristics of the software that controls the test and monitors its correctness.

The paper presents an original design of a single compression machine for combustion study. The principle of operation is based an old concept, utilizing the inertia energy of a flywheel to accelerate the crank mechanism and the attached piston to compress rapidly the combustible mixture in the combustion chamber. A square piston geometry was adopted to allow visualization of the compression and combustion processes in directions perpendicular to the cylinder axis. To avoid the extensive scratching of glass walls by the moving piston, a special multi-action clutch-brake unit was used; this facilitates coupling of the flywheel with the crank mechanism during the single piston stroke and subsequent immediate uncoupling and fast stopping of the piston. The whole operating cycle can be completed within no more than two revolutions of the crankshaft. The design details of the machine, its acceleration characteristics and a sample of the visualized combustion process are presented.

The paper presents a general idea of the acceleration test method and the design, construction and testing of the inertial dynamorneter test rig developed for small, high performance two-stroke engines. The method is universal and can be also used for four-stroke engines but it is especially useful for the two-stroke ones. The testing procedure is described and the advantages of that type of investigation method are pointed out. It has been proved that the reliability of the method is satisfactory. It was also proven that the individual construction of the inertial dynamorneter of good quality can be performed individually and that it can be a very useful investigation tool in engine tuning practice. The point has been stressed that the major advantage of that method is the possibility of the instantaneous measurement of the engine power characteristic during unsteady engine operation (acceleration) where the time for the single run does not exceed ten seconds.

This article presents shortly reasons for improving designs of turboprop and turboshaft engines, and describes aero-thermodynamic aspects of methods or modification of these devices. The theoretical analysis of methods or modification concerns general changes or efficiency, flow, and rating. The influence of the following factors on engine performance is presented: change of efficiency or engine units, increase of compression and flow rate by using a compressor zerostage, change of compressor pressure ratio, changes of gas temperature keeping the gasgenerator rotational speed constant by adjusting the minimal throat area of turbine nozzle guide vanes, turbornachinery modelling, and changes of rotational speed of ratings.

Plastic rocks can creep, therefore the knowledge of the rheological properties of the drilled formations is an important element of the drilling process and when choosing borehole designs. These properties of plastic formations also influence the way in which appropriate drilling technology and drilling mud properties are selected. The article presents the effect of basic rheological parameters of salt from the Fore-Sudetic Monocline deposit on the drilling of boreholes in the mining area of KGHM Polska Miedź, which in the future can be used as a good drilling practice to improve the safety and efficiency of drilling.

The process of drilling in plastic rocks may be hindered. Salt is a plastic rock and in the analyzed rock mass it is deposited at a considerable depth. The caprock exerts big loads on it, beside the temperature in the deposit intensifies the rheological properties of the rock. The creep process causes that the borehole contracts, therefore the knowledge about the rheological properties of the drilled rock is very important for establishing the safe time in which the well may remain uncased. The paper is devoted to the influence of basic rheological parameters of salt bed in the Fore-Sudetic Monocline on the process of drilling of a borehole in the area of KGHM Polska Miedź as these data can be used in drilling practice in the future.

This paper presents an experimental study on the leaching of heavy metals, toxic chemicals and persistent organic pollutants (POPs) – PAH, PCB and HCB – from soil dredged from the coastal area of Västernorrland in northern Sweden. The soil was stabilized with cement/slag. Samples were subjected to modified surface leaching and shake tests using technical standards of the Swedish Geotechnical Institute (SGI). The experiments were performed using different blends of binding agents (30/70, 50/50, 70/30) and binder quantities (120 and 150 kg/m3) to analyze their effects on leaching. Soil properties, tools, and workflow are described. Binders included Portland cement and ground granulated blast furnace slag (GGBFS). Samples were tested to evaluate the min/max contents of pollutants (μg/l) for heavy metals (As, Ba, Pb, Cd, Co, Cu, Cr, Hg, Mn, Mo, Ni, S, V, Zn) and the hydrocarbon fraction index in the excess water. The leaching of heavy metals and POPs was assessed in sediments after the addition of the binder. The comparison was made against the two mixes (cement/slag in 30/70% and high/low binder with low/high water ratio). The results showed that 70% slag decreases the leaching of heavy metals and POPs. The equilibrium concentrations of DOC and heavy metals at L/S 10 (μg/l) were measured during the shake experiments to compare their levels in the groundwater that was used as a leachate. The leached content was assessed at L/S 10 in the upscaling experiments using four samples for PAH, PCB and various fractions of hydrocarbons: C10–C40, C10–C12, C12–C16 and C35–C40. The shake test showed a decrease in the leaching of heavy metals and POP substances from the soil subjected to stabilization by a higher amount of slag added as a binder. A binder blend with 30% cement and 70% of GGBFS showed the best performance.

The engine simulations have become an integral part of engine design and development. They are based on approximations and assumptions. The precision of the results depends on the accuracy of these hypotheses. The simplified models of frozen composition, chemical equilibrium and chemical kinetics provide the compositions of combustion products for engine cycle simulations. This paper evaluates the effects of different operating conditions and hypotheses on the exergetic analysis of a spark-ignition engine. The Brazilian automotive market has the highest number of flex-fuel vehicles. Therefore, a flex-fuel engine is considered for simulations in order to demonstrate the effects of these different hypotheses. The stroke length and bore diameter have the same value of 80 mm. The in-cylinder irreversibility is calculated for each case at the closed part of the engine cycle. A comparative analysis of these hypotheses provides a comprehensive evaluation of their effects on exergetic analysis. Higher values of accumulated irreversibility are observed for the oversimplified hypothesis.

At the beginning of the year 2024, 65 years will have passed since the establishment of the Chamber of Experts of the Association of Polish Electrical Engineers (SEP). During this period, SEP underwent significant changes. Particularly serious changes in the conditions for practicing association expertises have occurred in recent years, along with dynamic economic and political changes in Poland. Expertise is strongly based on economic conditions and the ways in which scientific, technical and industrial competences are expanded and available in the society. In the past, these highest competencies were quite strictly limited to well-organized professional communities related to scientific and technical associations such as SEP, and federal bodies such as NOT. Competencies were also generated in the best industrial centres associated with academic polytechnic centres. Today the role of expertises in electrical, electronics and ICT engineering is undergoing significant changes.

Thermoacoustic converters are devices for direct conversion of acoustic energy into thermal energy in the form of temperature difference, or vice versa – for converting thermal energy into an acoustic wave. In the first case, the device is called a thermoacoustic heat pump, in the second – thermoacoustic engine. Thermoacoustic devices can use (or produce) a standing or travelling acoustic wave. This paper describes the construction and properties of a single-stage thermoacoustic engine with a travelling wave. This kind of engine works using the Stirling cycle. It uses gas as a working medium and does not contain any moving parts. The main component of the engine is a regenerator equipped with two heat exchangers. Most commonly, a porous material or a set of metal grids is used as a regenerator. An acoustic wave is created as a result of the temperature difference between a cold and a hot heat exchanger. The influence of working gas, and such parameters as static pressure and temperature at heat exchanger on the thermoacoustic properties of the engine, primarily its efficiency, was investigated. The achieved efficiency was up to 1.4% for air as the working medium, which coincides with the values obtained in other laboratories. The efficiency for argon as working gas is equal to 0.9%.

This article proposes an analytical model of a system with priorities servicing a mixture of different elastic traffic streams. The model presented in the article was developed as the extension of earlier works published by the authors. It utilizes the concept of equivalent bandwidth and then, following bandwidth discretization, uses the dependencies introduced on the basis of the assumptions adopted for the generalized Kaufman-Roberts formula and for the model of a full-availability group with traffic compression. The article presents a possibility of using the proposed model to model the radio interface in a multi-service mobile network and provides an example of the above with the interface of an LTE network. Since the proposed model is an approximate one, the results of the calculations are compared with the results of simulations. A comparison of the results confirms an acceptable level of accuracy of the model. The model can be successfully used in the analysis and design of links and nodes of telecommunication and computer networks.

The time period of a jet engines full acceleration (from idle run rotating speed to full thrust) is a very important operational parameter. Minimization of this period is an important problem to be solved during the design of the fuel supply and control system. There are many methods of acceleration process control, especially in the case of engines with complicated design configurations. This work presents the problem of acceleration of a simple, single spool turbine jet engine with a so-called stable geometry, in which only one input (control) signal exists - fuel flow rate. Two methods of acceleration control consisting of limitation of the maximum allowable temperature of working medium in front of and behind the turbine in transient states were analyzed. In order to avoid difficulties associated with the direct measurement of actual temperatures, the so-called nonlinear engine observer was applied. With the use of the computer simulation method it was proven that the control algorithm with the limited maximum temperature in front of the turbine makes it possible the shortening of the acceleration time period significantly in comparison with a similar algorithm, that realizes the limitation of temperature behind the turbine.

Many groups of researchers have focused on the design of micro turbine engines in recent years. Since turbo-component efficiency becomes very low due to the downsizing effect, an important problem arises of how to obtain thermal efficiency high enough to produce the positive power required. The micro wave rotor is expected to be applied for the improvement of the performance of ultra micro gas turbines, increasing the cycle pressure ratio. Wave rotors can also be built in another configuration. Applying only a combustion chamber and using oblique blades to form the rotor cells, net power can be taken from the rotor. In that way, the use in a micro scale of an inefficient turbo unit can be omitted. Such a solution in a form of wave engine was developed and practically realised by Weber [ 15] and Pearson [8], [9], [ IO] in centimetre scale. Conventional construction of wave engines in a form of wave rotor can not be directly realized in MEMS technology. The new idea of a wave disk developed by Piechna, Akbari, Iancu,and Mueller [II] and independently by Nagashima and Okamoto [7] gives the possibility of easy implementation of the wave engine idea in MEMS technology. In the proposed solution, the wave disk plays the role of an active compressiondecompression unit and torque generator. Appropriate port geometry with oblique blades forming the disk channels generates torque. The engine disk rotates with a speed much lower than the conventional turbo-unit that simplifies the bearing problem. Also, the construction of electric generator can be simpler. The paper presents the proposed flow schemes, thermodynamic cycle, exemplary engine construction and some results of simulation of the MEMS wave engine using the wave disk.

The article presents subject matter related to the assessment of the suitability of the built-up area, including the occurrence of sinkholes on the surface. The investment plot, which is the subject of the analysis, is located in the central part of the Upper Silesian Coal Basin, where shallow exploitation of coal seams was conducted in the past. At present it is a post-mining area, located at a large distance from active mines. It has an attractive administrative location and good transport connection with the main road connecting the cities of the Silesian agglomeration. These advantages make it particularly attractive in terms of use for various types of investments. The geological and mining factors are not favorable in the area in question, mainly due to the shallow mining exploitation conducted in the past and the access excavations on small depth and an unknown method of liquidation. These reasons are the cause of some restrictions in the use of construction, for which taking the appropriate solutions is recommended. According to the study of (Rules... 2009), the category of mining land should be defined for the areas of liquidated mining plants due to the limitation in construction use. The authors of the article made an attempt to determine it, and they analyzed the geological and mining conditions for this purpose, mainly including mining exploitation conducted in the past. On the basis of the obtained results and own experience, the type of expected hazards and its assessment were determined The probability of the occurrence of the inclusions according to the Chudek-Olaszowski method (Chudek et al. 1988) was assumed as a measure of the hazard.

This paper aims to evaluate the effects of blended binders on the development of strength in moraine soils by optimising the proportion of several binders. We tested three types of soil as a mixture of moraine soils: A (sandy clay), B (clayey silt) and C (silty clay), collected in southern Sweden. The soil was compacted using a modified Proctor test using the standard SS-EN 13286-2:2010 to determine optimum moisture content. The particle size distribution was analysed to determine suitable binders. The specimens of types A, B and C, were treated by six different binders: ordinary Portland cement (OPC); hydrated lime (Ca(OH)2); ground granulated blast furnace slag (GGBFS) and their blends in various proportions. The strength gain in soil treated by binders was evaluated by the test for Unconfined Compressive Strength (UCS) against curing time. For soil type A, the strength increase is comparable for most of the binders, with the difference in behaviour in the UCS gain. The OPC/lime, GGBFS and hydrated lime showed a direct correlation, while OPC, OPC/GGBFS and GGBFS/hydrated lime – a quick gain in the UCS by day 28th. After that, the rate of growth decreased. Compared to soil type A, Ca(OH)2 performs better on the stabilisation of soil type B. Besides, the hydrated lime works better on the gain of the UCS compared to other binders. The GGBFS/Ca(OH)2 blend shows a notable effect on soil type A: the UCS of soil treated by Ca(OH)2 performs similarly to those treated by OPC with visible effects on day 90th. Cement and a blend of slag/hydrated lime demonstrated the best results for soil type B. An effective interaction was noted for the blends GGBFS and hydrated lime, which is reflected in the UCS development in soils type A and B. Blended binder GGBFS/hydrated lime performs better compared to single binders.

The paper presents a new method of determination of economic benefits of land consolidation of farms, which result from reduction of land parcels' number. A model method and a logical method have been applied. The discussed economic benefits have been determined by means of comparing economic evaluation of a model farm's land configuration before and after land consolidation. As a result of analysis, a mathematical formula that describes an economic benefit of land consolidation, resulting from the reduction of land parcels number, has been derived. The economic benefit is a function of the differences between the numbers of arable fields and the differences between the area of an arable lands and green lands of a farm, before and after land consolidation, as well as constant parameters and slope of linear regression equations for the models of such fields. The benefit does not depend on the area of farms.

ln laboratory electrically heated entrained flow reactor with quasi one-dimensional laminar flow the influence of fuel properties on the nitrogen oxide emission for 23 coals of various rank from brown coal, bituminous coal to anthracites has been examined. For one brown coal type twofold increase of nitrogen content resulted in NO, emissions increase of about 30%. Increasing rank from brown coal to bituminous coal increases NO emissions and next a fall in the anthracites range. With nitrogen content increase NO - emission grows a~d the ratio of fuel nitrogen conversion to nitrogen oxide decreases. Experiments results and their statistical analysis were used to determine relationships describing NO, emissions and conversion ratio of fuel nitrogen to nitrogen oxide as functions of two variables. describing coal properties, i.e. nitrogen content and fuel ratio (fixed carbon to volatile matter ratio).

The paper presents the results of simulation tests of hydraulic resistance and temperature distribution of the prototype Stirling alpha engine supplied with waste heat. The following elements were analyzed: heater, regenerator and cooler. The engine uses compressed air as a working gas. Analyses were carried out for three working pressure values and different engine speeds. The work was carried out in order to optimize the configuration of the engine due to the minimization of hydraulic resistance, while maintaining the required thermal capacity of the device. Preliminary tests carried out on the real object allowed to determine boundary and initial conditions for simulation purposes. The simulation assumes that there is no heat exchange between the regenerator and the environment. The solid model used in simulation tests includes the following elements: supply channel, heater, regenerator, cooler, discharge channel. Due to the symmetrical structure of the analyzed elements, simulation tests were carried out using 1/6 of the volume of the system.