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CFD Impulse Flow Simulation Through Shaped Nozzles
Get PDFPressure pulsations in volumetric compressor manifolds are important issues in the compressor plant operation. For pressure pulsation attenuation, mufflers designed using the Helmholtz resonator approach are applied. Nowadays, the variable revolution speed compressors requires new design methods for pressure pulsation damping elements. One of the possibilities to attenuate the pressure pulsations is the introduction of specially shaped nozzles in the gas duct flow. In this paper, the impulse flow simulations conducted in FLUENT/ANSYS. The experimental validation of the simulation results is also presented
Wind-tunnel modelling of the phenomenon of railway wagons rolling over under strong crosswind action
Get PDFThis paper deals with the derivation of similarity criteria for the phenomenon of railway wagons rolling over when exposed to strong crosswinds. Utilizing these criteria, the authorial method for the determination of the aerodynamic coefficient of the rollover moment is also presented in the paper
Asynchronous buffer read method in development of DAQ application for supporting research of hydraulic systems
Get PDFThe paper presents a method of data acquisition from a DAQ card using a direct memory access (DMA) and an asynchronous read of data buffer with the FIFO queue. The method can be used to acquire measurement data in Windows™ system when the required read frequency is higher than the system’s clock frequency. The method was used in practice to measure high-speed pressure and position changes in a two cylinder hydraulic system with two-state fast switching valves
Centres of civic activity and the idea of the city
Get PDFThe author presents the results of a research project carried out under the academic supervision of S. Juchnowicz in the 80s of the last century and, from the perspective of thirty years, undertakes the effort of verification whether the prognostic assumptions adopted at that time were accurate. The article presents the results of the research and the author’s personal reflections on the evolution of Kraków
Calculation methods for eddy current losses with the example of a permanent magnet excited synchronous machine inside the threshing cylinder of a combine harvester
Get PDFElectrical drives become more and more interesting for many applications in mobile machines including farming equipment. In this paper, the electromagnetic design of a threshing cylin der for an electrical combine harvester with a function-fitted external rotor and an inner stator is shown. Special attention will be paid to the calculation of the eddy current losses within the magnets through different FEM methods. The influence on the losses of segmentation of magnets in tangential and axial directions is shown
Equivalent circuits used in the diagnostics of insulation in power transformers
Get PDFAn equivalent circuit of the insulation system in power transformers comes in many forms. In tests for the dielectric loss tangent (tgδ) of the main insulation, the equivalent circuit has been simplified to two-terminal RC series connected or parallel connected circuits. For direct current tests of groundwall insulation modelling, two two-terminals circuits are required – one for charging and shorting, the other for the voltage recovering after shorting. The model turn-to-turn insulation may also be presented by two-terminal circuits. The parameters of the two-terminal circuit can be determined by direct current. The tested winding is energized by DC voltage, the current is interrupted and the voltage waveform on the terminals of the winding is recorded. The parameters of turn-to-turn insulation (equivalent circuit parameters) are calculated from the voltage waveform and they can be used for diagnostic purposes
The world of architecture
Get PDFThe architecture of theatre and the scenic urban space, which has always provided a venue for celebrations and been the scene for collective actions, essentially concerns those places that contain their theatricality in the architecture, like all those places whose shapes make the rituals of performance and the event possible by mimicking theatrical forms
A note on singularity of fibers of singular sets
Get PDFThe paper presents a general theorem on fibers of singular sets: Let D1 be a connected σ-compact Josefson manifold and let D2 be a σ-compact complex manifold. Let Ω⊂D1×D2 be a domain and let Ω⊂M be a singular set with respect to the family Ƒ
New opportunities of financing revitalisation of historical garden compositions in the light of their conservation
Get PDFThe 21st century has brought new opportunities for revitalization projects in Poland (including those related to historical parks and gardens) under the framework of EU subsidies. Greenery compositions, often significantly damaged and with poorly preserved historical structure, have gained a chance to survive and be properly managed. However, the problem is that design and construction works are often conducted in haste, and adapted to the specific requirements of EU projects, often resulting in the unification of adopted solutions and incongruence with historical structures (e.g. “Orlik” sports fields or “Radosna szkoła” playgrounds, where even the colour scheme is imposed by the project), which obviously causes irreparable damage. The authors wish to present the above mentioned problems illustrated with an example of the revalorisation process of a park in Chociw, one of the valuable manor-park complexes in the Łódź Province. They present both positive and negative influence which financial support might have on a venture of this kind
Da Capo City
Get PDFThe city is lauded as one of the most important products of civilisation. However, cities differ from each other, and socialist cities are an altogether different phenomenon. All types of so- cialist cities share one characteristic – they have no social spaces. The article faces the issue of revitalisation of post-socialist cities through redevelopment of their public spaces