Automatic validation of vibration signals in wind farm distributed monitoring systems

A rapid growth of wind farms as a leading renewable energy sector has compelled a number of companies to develop dedicated distributed systems of monitoring and diagnosis (SM&D). Such systems are capable of early mechanical faults detection, which prevents from costly critical repairs. Fault detection of wind turbines is based on vibration and process signals analysis. Modern SM&D are usually advanced hardware and software technological products, which on the basis of collected data are capable of continuous execution of enormous number of analyses. However, the expansion of distributed systems has disclosed new challenges accompanying the transition from a singular signal analysis to automatic interpretation of large data sets. The paper deals with the assessment of data acquisition final products, namely the correctness of vibration signals recording process. The proposed validation, which is to be implemented a priori to data analysis, is required for significant calculation of any signal features as well as for legitimate storage of raw waveforms in the system database. The latter aspect is especially important in terms of gigabytes of disk space frequently wasted for corrupted data. The paper presents a step-by-step method for automatic signal validation, which can be implemented on a personal computer. Finally, the algorithm is evaluated on a real wind turbine database.     

Simplified numerical study of evaporation processes inside vertical tubes

The paper presents a simplified numerical model of evaporation processes inside vertical tubes. In this model only the temperature fields in the fluid domain （the liquid or two-phase mixture） and solid do- main （a tube wall） are determined. Therefore its performance and efficiency is high. The analytical formulas, which allow calculating the pressure drop and the distribution of heat transfer coefficient along the tube length, are used in this model. The energy equation for the fluid domain is solved with the Control Volume Method and for the solid domain with the Finite Element Method in order to de- termine the temperature field for the fluid and solid domains.     

Ethylene/1-olefin copolymerization behaviour of vanadium and titanium complexes bearing salen-type ligand

Ethylene/1-olefin copolymerization using vanadium and titanium complexes bearing tetradentate [O,N,N,O]-type ligand and EtAlCl₂ or MAO as a cocatalyst is carried out. In the presence of the vanadium complex activated with EtAlCl₂ is observed (a) negative “comonomer effect”, (b) high comonomer incorporation and narrow chemical composition distribution (CCD), (c) unexpected copolymer microstructure, and (d) increased molecular weight of copolymers when compared with the homopolymer. In contrast, titanium catalyst gives copolymers with lower 1-olefin content and broad CCD. Supported complexes show higher activity, lower 1-olefins incorporation and give copolymers with ultra high molecular weights.     

Environmentally friendly pathways for the evaluation of investment projects using life cycle assessment (LCA) and life cycle cost analysis (LCCA)

Issues related to improvement in the quality of products and to environmental protection in the economic policy of many countries and in the strategies of institutions and international organisations (e.g. European Union) have increased in importance in recent years as a consequence of the increase in environmental awareness of consumers. All these institutions currently recommend a comprehensive assessment of the effectiveness of planned projects during the decision-making process taking into account both economic and environmental factors. It is, therefore, important to develop methods and tools to assess environmental performance as a support to a proper choice of investment activities. The aim of this paper is to develop algorithms to link the life cycle assessment (LCA) model associated with environmental issues and the life cycle cost analysis (LCCA) model associated with economic factors to permit an integrated assessment of investment projects. The combination of LCA and LCCA results enables the assessment of ongoing or planned investments and should be used as a priority in making strategic decisions. In this paper, three environmentally friendly pathways (algorithms) using LCA–LCCA indicators as a support for decision-making processes were proposed: the first for implementing any environmental investments, the second for modernisation and innovation investments, and the third for new investments.     

A New One/Two-Dimensional Model of the Conjugate Heat Transfer in Waterwall Tubes of the Supercritical Steam Boiler Combustion Chamber

An important issue arising in supercritical steam boilers is to avoid the tube wall overheating due to high heat fluxes transferred from flue gases to the fluid. The paper presents a new hybrid one/two-dimensional model of the fluid heating in waterwall tubes in the combustion chambers of steam boilers for supercritical steam parameters. The model is based on distributed parameters. The analysis concerns tubes with externally finned surfaces. Using the proposed model, it is possible to estimate zones and locations where the tube wall overheating may occur. One-dimensional equations describing the mass, momentum and energy conservation are formulated and solved for the fluid domain. Each analyzed cross section of the finned waterwall tube is divided into 20 control volumes for which energy balance equations are solved in a two-dimensional space. In order to analyses the conjugate heat transfer between the waterwall tube and the fluid, the heat transfer coefficient is computed using the Kitoh correlation. The computations assume a variable heat flux along the combustion chamber height. Also, the heat flux variation on the waterwall tube circumference is incorporated within the model. The reduction in dimensionality in both the fluid and the solid domains leads to an improvement in the computational performance compared to complex three-dimensional computational fluid dynamics simulations. The paper presents an application of the proposed hybrid model to simulate heat and flow processes occurring in waterwall tubes of a supercritical boiler operating in one of the Polish power plants. The results of the simulations are compared with the data obtained from measurements and good agreement is obtained. Therefore, the developed model can be successfully applied, e.g. in simulators of the supercritical power boiler operation.     

At the Edges of Photosynthetic Metabolic Plasticity—On the Rapidity and Extent of Changes Accompanying Salinity Stress-Induced CAM Photosynthesis Withdrawal

The common ice plant (Mesembryanthemum crystallinum L.) is a facultative crassulacean acid metabolism (CAM) plant, and its ability to recover from stress-induced CAM has been confirmed. We analysed the photosynthetic metabolism of this plant during the 72-h response period following salinity stress removal from three perspectives. In plants under salinity stress (CAM) we found a decline of the quantum efficiencies of PSII (Y(II)) and PSI (Y(I)) by 17% and 15%, respectively, and an increase in nonphotochemical quenching (NPQ) by almost 25% in comparison to untreated control. However, 48 h after salinity stress removal, the PSII and PSI efficiencies, specifically Y(II) and Y(I), elevated nonphotochemical quenching (NPQ) and donor side limitation of PSI (Y_ND), were restored to the level observed in control (C₃ plants). Swelling of the thylakoid membranes, as well as changes in starch grain quantity and size, have been found to be components of the salinity stress response in CAM plants. Salinity stress induced an over 3-fold increase in average starch area and over 50% decline of average seed number in comparison to untreated control. However, in plants withdrawn from salinity stress, during the first 24 h of recovery, we observed chloroplast ultrastructures closely resembling those found in intact (control) ice plants. Rapid changes in photosystem functionality and chloroplast ultrastructure were accompanied by the induction of the expression (within 24 h) of structural genes related to the PSI and PSII reaction centres, including PSAA, PSAB, PSBA (D₁), PSBD (D₂) and cp43. Our findings describe one of the most flexible photosynthetic metabolic pathways among facultative CAM plants and reveal the extent of the plasticity of the photosynthetic metabolism and related structures in the common ice plant.     

The VIT technology for rapid detection of Listeria monocytogenes and other Listeria spp

Detection of Listeria monocytogenes is generally performed in a two-step cultural enrichment process and takes on average 1 week until the biochemical identification of a L. monocytogenes suspicious colony is completed. However, food processing companies depend increasingly on test methods, which attempt to generate results comparable to standard methods but in reduced time-frame and which allow to release produced batches dependent on such results. In the present study, the vermicon identification technology (VIT), a rapid commercial test system using fluorescently labelled gene probes, was compared to a cultural standard method. In total, 298 naturally contaminated samples were analysed. The sensitivity and the specificity of the VIT system were 100% for the detection of L. monocytogenes and 97.1% and 100%, respectively, for the detection of the genus Listeria.     

Gas‐phase flow resistance of metal foams: Experiments and modeling

Based on experimental results of gas flow resistance through two metal foams, NC 2733 and Ni 2733, a modeling is performed to adjudicate governing flow mechanism. Two essential models are considered: developing laminar flow within short capillary channel (i.e., foam pore) and flow around solid body (foam strut modeled as cylinder or sphere), each of them of some variants. Foam geometry was studied using computer microtomography. The model of flow around a sphere (diameter equal to strut thickness) gives the best conformity with experiments. © 2017 American Institute of Chemical Engineers AIChE J, 63: 1799–1803, 2017     

Antioxidant (Tocopherol and Canolol) Content in Rapeseed Oil Obtained from Roasted Yellow-Seeded <Emphasis Type="Italic">Brassica napus</Emphasis>

In this study, the effect of temperature (140, 160, 180 °C) and roasting time (5, 10, 15 min) on the bioactive compound content (canolol, tocopherol and plastochromanol‐8) of cold‐pressed oil from yellow‐seeded rapeseed lines of different colors was investigated. Roasting increased the peroxide value in the seed oils compared to the oils from the control samples. However, roasting did not affect the acid values of the oils, which were 1.15–1.47 and 1.30–1.40 mg KOH/g, for line PN1 03/1i/14 (yellow seeds) and line PN1 563/1i/14 (brown seeds), respectively. In this study, the seeds of line PN1 03/1i/14 were characterized by different changes in canolol content during roasting than the seeds of PN1 563/1i/14. There was a 90‐fold increase in canolol for the line PN1 03/1i/14 (768.26 µg/g) and a 46‐fold increase for the line PN1 563/1i/14 (576.43 µg/g). Changes in tocopherol and PC‐8 contents were also observed. There was an increase in the contents of γ‐T and PC‐8 in the oils obtained from the seeds roasted at 180 °C for 10 and 15 min. γ‐T content increased by 17–18% after 15 min of roasting, whereas the PC‐8 content increased twofold.     

Methods of Selenium Supplementation: Bioavailability and Determination of Selenium Compounds

Selenium, a “dual-surface” element, maintains a very thin line between a level of necessity and harmfulness. Because of this, a deficiency or excess of this element in an organism is dangerous and causes health-related problems, both physically and mentally. The main source of selenium is a balanced diet, with a proper selection of meat and plant products. Meanwhile, the proper assimilation of selenium into these products depends on their bioavailability, bioaccessibility, and/or bioactivity of a given selenium compound.

From the time when it was discovered that selenium and its compounds have a significant influence on metabolic processes and in many countries throughout the world, a low quantity of selenium was found in different parts of the environment, pressure was put upon an effective and fast method of supplementing the environment with the help of selenium. This work describes supplementation methods applied with the use of selenium, as well as new ideas for increasing the level of this element in various organisms.

Based on the fact that selenium appears in the environment at trace levels, the determination of total amount of selenium or selenium speciation in a given sample demands the selection of appropriate measurement methods. These methods are most often comprised of a sample preparation technique and/or a separation technique as well as a detection system. The work presents information on the subject of analytical methods used for determining selenium and its compounds as well as examples in literature of their application.