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An Influence of Factors of Flow Condition, Particle and Material Properties on Slurry Erosion Resistance

Abstract

The degradation of materials due to slurry erosion is the serious problem which occurs in the power industries. The paper presents actual knowledge about an influence of individual factors connected with flow conditions, particles and material properties on the slurry erosion resistance. Among the factors connected with operating conditions, an influence of impact angle, and velocity of impact, particle concertation and liquid temperature have been described. In case of the factors connected with solid particle properties, an influence of the size, shape and hardness have been discussed. In the part devoted to the impact of material properties, due to different types of materials, the issues of resistance to erosion of slurries related to the properties of steel, ceramics and polymers are discussed separately. In the paper has been shown that a change of any of mentioned factors causes a change in the erosion rate due to the synergistic effects that accompany to slurry degradation.

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The Influence of Pulsating Tensile Stress on Residual Magnetic Field of P91 Steel Samples

ABSTRACT

Measurements of Residual Magnetic Field RMF (the tangential component parallel to the load direction) were taken on the surface of P91 steel plate samples (X10CrMoVNb9-1) subjected to periodic pulsating tensile cyclic loads with the use of flux-gate and magneto impedance sensors, and preliminary measurement results are compiled and analyzed. The study investigates how the microstructure and load cycle parameters affect the RMF changes due to stress variations. Each combination of parameters: microstructure and load cycle corresponds to the characteristic variability pattern of magnetization and its maximum and minimum values.

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Investment Opportunities in Ecological Farms with Various Production Branches

Abstract

Development investment capacity of farms depends on their potential and scale of production, and thus its revenue, which determines the scale of investment purchases. Most specialized farms have growth potential. Farmers take great interest in modernization and investing in new technologies, machinery and agricultural land, as confirmed by market analysis. Literature references offer information regarding the needs and investment opportunities of territorially diversified farms running conventional production, however the aim of the work is to determine the investment possibilities of organic farms with various production branches. The research included 50 farms certified as ecological producers. In order to answer the question which type of business has the greatest development potential, the examined facilities were divided into branch groups.

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Logistic and Economical Preconditions for Production of Pellets From Sawdust

Abstract

The objective of the paper was to determine the costs of production and production effectiveness of pellets made of sawdust and characteristics of logistics of raw material carriage and distribution of pellets. The scope of the paper covered the research carried out in the branch of DREWEX company located in Chotelek town (Świętokrzyskie voivodeship, Province of Busko Zdrój). Unit costs of pellets production were: 513.4 PLN∙t−1 for option 1, 423.3 PLN∙t−1 for option 2 and 393.3 PLN∙t−1 for option 3. The most favourable was option 3 when the pellets were produced on the technology line in the 3-shift system day and night. The average distance to seven cities from which sawdust was delivered was 43.6 km and the distance to which production was distributed to ten cities was on average 105.5 km.

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Luminescent properties of a novel reddish-orange phosphor Eu-activated KLaSiO4

Abstract

A novel reddish-orange emitting phosphor Eu-activated KLaSiO4 was synthesized by the conventional solid-state reaction at 1200 °C. The luminescence properties of KLaSiO4:Eu phosphor were investigated, and the critical concentration of the activator ion (Eu3+) was established as 0.02 mol per formula unit. Chromaticity coordinates of a typical KLa0.98SiO4:0.02Eu phosphor were x = 0.614 and y = 0.385. The phosphor exhibited reddish-orange luminescence with dominating emission at 612 nm, corresponding to 5D07F2 of Eu3+. Furthermore, the phosphor was characterized by excellent thermal stability, implying its potential use in white light emitting diodes.

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Mechanical Analysis Process of a Coaxial Counter Rotor for Applications in Unmanned Ultra-Light Units

Abstract

As the rotor configuration has the most impact on helicopter properties, the process of determination the assumptions for rotor design is a very important factor in the early stage of rotorcraft development. The following paper presents a mechanical analysis process used at the Institute of Aviation to quickly develop a coaxial rotor prototype applicable in ultra-light unmanned helicopter which has the potential for further improvement of its flight parameters. The article describes the rotor analysis process due to its feasibility based on commercially available solutions, the process of formulating assumptions for the entire structure, MES analysis of the rotor parts all leading to creation of the rotor prototype.

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Mechanical and mathematical research of local deformations of a steel roller shell with a variable geometry of contact surface

Abstract

The article is devoted to solving the fundamental and applied problem of nonlinear structural mechanics of machines by introducing into the drum two additional stop cylinders with supporting rollers at the end and adjustable length, providing a given elliptical or circular shape of a flexible shell with a smoothly variable geometry in the area of its contact with compacted pavement material. Compaction of soil, gravel and asphalt concrete in the sphere of road is not only an integral part of the technological process of the roadbed, road foundation and surface construction, but it is actually the main operation to ensure their strength, stability and durability. The quality, cost and speed of road construction, the possibility of using fundamentally new technologies, structures and materials is largely determined by the availability of modern road machinery.

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Methods for Asssessing Energy Efficiency of Grain Dryers

Abstract

The article presents an algorithm for calculating selected energy assessment indexes for grain driers. Particular attention was paid to the conversion of the equations obtained for the operating conditions of the drying process into equations allowing the calculation of indexes for the standard drying conditions. The indexes obtained allow a proper comparison of dryers operating in varied atmospheric conditions, as well as humidity and temperature of the dried material.

Open access
Mixed structure Zn(S,O) nanoparticles: synthesis and characterization

Abstract

In the present work, mixed structure Zn(S,O) nanoparticles have been synthesized using solution based chemical coprecipitation technique. Two different zinc sources (Zn(CH3COO)2·2H2O and ZnSO4·7H2O) and one sulfur source (CSNH2NH2) have been used as primary chemical precursors for the synthesis of the nanoparticles in the presence and absence of a capping agent (EDTA). The structural, morphological, compositional and optical properties of the nanoparticles have been analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), Fourier transmission infra-red (FT-IR) and UV-Visible (UV-Vis) spectroscopy. XRD revealed the formation of mixed phases of c-ZnS, h-ZnS and h-ZnO in the synthesized nanoparticles. The surface morphology was analyzed from SEM micrographs which showed noticeable changes due to the effect of EDTA. EDX analysis confirmed the presence of zinc, sulfur and oxygen in Zn(S,O) nanoparticles. FT-IR spectra identified the presence of characteristic absorption peaks of ZnS and ZnO along with other functional group elements. The optical band gap values were found to vary from 4.16 eV to 4.40 eV for Zn(S,O) nanoparticles which are higher in comparison to the band gap values of bulk ZnS and ZnO. These higher band gap values may be attributed to the mixed structure of Zn(S,O) nanoparticles.

Open access
Multi-criteria decision analysis for simplified evaluation of clean energy technologies

Abstract

Technology assessment (TA) is not a new concept. High value energy technology identification needs to be followed by a decision process in which all shareholders contribute. A case study on Combined and Heat Power (CHP) technologies considered is presented to illustrate the applicability of fuzzy analytical hierarchy assessment approach (FAHP). The goal of this paper is to identify and evaluate the best variant of CHP technologies using multi-criteria that are technical feasibly and cost effective reflecting performance parameters. The results depict that technology A2 with an overall ranking of 0.438 is the best alternative compared to others. Taking into consideration decision parameters for the section, A1 is found to be relatively most important with a rating of 0.434 with its reliability and cost effectiveness. The presented fuzzy-based methodology is general expected to be used by a diverse target groups in energy sectors.

Open access