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1

A novel testing setup for determining the flexural properties of tunnel segmental joints: Development and application

Zhang Z. X., Liu W., Zhuang Q. W., Huang X., Wang S. F., Zhang C., Zhu Y. T., Kwok C. Y.

Archives of Civil and Mechanical Engineering

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2019

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Vol. 19, no. 3

724--738

EN

A novel testing setup is developed for structural tests on segmental joints of shield tunnels. It lies on the ground and is a self-balanced system. The applied axial force and bending moment are coupled, and the combination of target axial force and bending moment at the joint can be achieved by adjusting the horizontally-applied forces. It is more economic and flexible than the traditional two-point bending testing setups. The effectiveness of internal force/moment transmission of the testing setup was verified by comparing the experimental data with theoretically-determined values and numerical simulation results. It was then applied to investigate the flexural behaviour of longitudinal joint of a deeply-buried tunnel subjected to both sagging and hogging moments. The rotational stiffnesses of the testing joint were determined. The influences of bending moment and axial force on joint defor-mation were unified through eccentricity. In both the sagging moment and hogging moment cases, the joint deformation varied with eccentricity following a bilinear trend composed of an axial-force-dominant stage and a bending-moment-dominant stage. The slopes of the relationships between eccentricity and joint rotation angle are steeper in the hogging moment case than in the sagging moment case due to the absence of bolts at the extrados.

2

Synteza matrycowa kompozytów tlenku cynku stosowanych w ogniwach słonecznych uczulanych barwnikiem

Zhao N., Zhang C., Zhang P.

Przemysł Chemiczny

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2018

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T. 97, nr 2

195--199

PL

Tlenek cynku jest obiecującym materiałem do budowy anod ze względu na możliwość uzyskiwania go w postaci różnych nanostruktur oraz doskonałą ruchliwość elektronów. W celu poprawy działania ogniw fotowoltaicznych otrzymano nanostruktury ZnO i zastosowano je w elektrodach półprzewodnikowych. Jako podłoże warstwy ZnO zastosowano szkło z tlenku cyny domieszkowanego fluorem FTO (fluorine-doped tin oxide). Po wyżarzaniu pokryto je warstwą składającą się z mikrokulek polistyrenowych wytworzonych in situ metodą polimeryzacji wolnorodnikowej. Zarodki ZnO hodowano w mieszaninie azotanu cynku i heksametylenotetraaminy w celu wytworzenia różnych typów nanostruktur ZnO (struktura siatki 3D i struktura nanodrutu-nanocząstki) o dużej powierzchni właściwej. Warstwę kompozytową uczulono barwnikiem N719 i zastosowano w ogniwach słonecznych. Uzyskano efektywność konwersji energii 3,91%.

EN

ZnO was deposited from Zn(OAc)2 soln. on F-doped SnO glass substrate by spin coating. After the procedure was repeated 4 times, the layer was annealed at 400°C for 1 h and covered with template layer consisting of polystyrene microspheres in-situ produced by free radical emulsion polymerization. The seed layer was grown in the mixt. of Zn(NO3)2 and hexamethylenetetramine to produce ZnO of nanowire-nanoparticle structures with high sp. surface area. The template layer was then removed by heating at 500°C for 1 h under formation of ZnO nanostructures. Di(tetrabutylammonium)cis-bis(isothiocyanato)bis(2,2’- bipyridyl-4,4’-dicarboxylato)ruthenium(II) (N719 dye) was then deposited from its soln. on the composite surface and sensitized in dark for 1 h. The product was characterized by X-ray diffractometry, elec. impedance spectroscopy and scanning electron microscopy and then successfully used as a semiconductor electrode in a solar cell of improved performance.

3

Reliability based analysis and design of a tripod offshore wind turbine structure assuring serviceability performance

Zhang J., Kang W. H., Zhang C., Sun K.

Polish Maritime Research

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2018

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nr 4

139--148

EN

Typical tripod foundations are designed using deterministic computational models according to relevant standards and codes. However, for more cost-safety balanced design, uncertainties in significant parameters should be considered in preliminary design to ensure meeting a specific probabilistic safety target in the context of the complex configuration of a tripod structure. In this article, uncertainties associated with design parameters and modelling errors are considered using Monte Carlo simulations, in order to determine the key structural design parameters, and to determine the optimal balance between design parameters and design requirements. A Spearman rank-order correlation based analysis is carried out to understand the effects of design variables on maximum deformation, total weight, and natural frequency, and to have insight about important design parameters for improvement of a preliminary design. It is found that the tower diameter has the most significant effect on the maximum displacement on the hub as validated through engineering case studies. In addition, a statistical framework, which identifies influential design parameters and provides reliability evaluation, is proposed for the structural design of a tripod OWT system. The design cases considered in this study indicate that a simple deterministic design check cannot guarantee the required reliability level of the structure, and the cost-safety balance can be achieved by a reliability analysis with the consideration of the uncertainties in the structure.

4

The effect of polyacrylic acid on the surface properties of calcite and fluorite aiming at their selective flotation

Zhang C., Gao Z., Hu Y., Sun W., Tang H., Yin Z., He J., Guan Q., Zhu Y.

Physicochemical Problems of Mineral Processing

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2018

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Vol. 54, iss. 3

868--877

EN

In this study, the polyacrylic acid (PAA) was studied as a selective depressant for calcite in the selective flotation of fluorite and calcite, and the implications of this process for the separation of fluorite ore were studied using micro-flotation tests, and the results were analyzed with Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) analyses. The flotation tests indicated that the preferential adsorption of PAA onto calcite rather than sodium oleate (NaOl) could selectively depress the flotation of calcite, allowing its separation from fluorite at pH 7. The zeta potential of calcite became more negative with the addition of PAA rather than with NaOl. However, the characteristic features of PAA adsorption were not observed for fluorite, suggesting that NaOl preferentially adsorbed on the surface of fluorite, or that PAA could be replaced by NaOl on the fluorite surface. FT-IR and XPS analysis were utilized to obtain a better understanding of the mechanism by which PAA was more strongly adsorbed on the calcite surface than NaOl. This was revealed to occur through chemical bonding between the carboxyl group of PAA and the hydroxyl groups of the Ca species on the calcite surface, modifying the structure of the adsorbed layer. A possible adsorption mechanism, along with a postulated adsorption mode for the surface interaction between PAA and calcite, is proposed.

5

Kinetics and mechanism of one-step reductive leaching of manganese oxide ores by EDTA/EDTA-2Na

Zhang C., Wang S., Cao Z., Zhong H.

Physicochemical Problems of Mineral Processing

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2018

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Vol. 54, iss. 3

858--867

EN

In this research, the kinetics and mechanism of one-step reductive leaching of manganese oxide ores by ethylenediaminetetraacetic acid (EDTA) or its disodium salt (EDTA-2Na) in an aqueous medium have been investigated. The kinetic data of this reductive leaching process may be described by the Avrami model, and the apparent activation energy was determined to be 15.8 kJ·mol-1/7.9 kJ·mol-1 for leaching by EDTA/EDTA-2Na with a reaction order of -1.7/2.0. The EDTA/EDTA-2Na leach liquor characterized and analyzed by X-ray photoelectron spectra (XPS), Fourier transform infrared spectra (FTIR), and total organic carbon (TOC) determination denoted that the oxidation-reduction reaction happened between manganese(IV) and EDTA/EDTA-2Na, and a coordination complex, EDTA-manganese(II/III) formed. This new process can be easily used to leach manganese from manganese oxide ores in a moderate environment with the pH range of 5–8.

6

Contribution on fluid inclusion abundance to activation of quartz flotation

Yuan Y., Zhang L., Guan J., Zhang C., Wu J., Chen Z.

Physicochemical Problems of Mineral Processing

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2018

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Vol. 54, iss. 3

981--991

EN

In this study, comparative experiments were conducted on the recovery of quartz using flotation with different fluid inclusion abundances. A large number of fluid inclusions with various sizes have been found in natural quartz. Micrographs, inductively coupled plasma, electron probe microanalysis, homogenization temperature, Raman spectra, zeta potentials, X-ray photoelectron spectroscopy, scanning electron microscope, and energy dispersive spectrometer were used to characterize the fluid inclusions and quartz, as well as the adsorption tests and single mineral flotation experiments to investigate its floatability. The results demonstrated that it was more likely for quartz with higher fluid inclusion abundance to connect with Fe3+ sufficiently to achieve a high level of flotation recovery, due to the powerful collecting ability by sodium dodecyl sulphonate to Fe3+. Furthermore, the mechanism indicated that the adsorption between quartz and Fe3+ was a process of chemisorption.

7

Synthesis of LiNiO2 by two-step solid-state method

Li S., Wu Q., Zhang C., Zhu H., Zhang C., Wang X., Kong C.

Materials Science Poland

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2018

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Vol. 36, No. 1

107--111

EN

LiNiO2 was prepared through two-step solid-state reaction by mechanochemical method and heat treatment, using LiOH (Li2 CO3) and Ni(OH) 2 as starting materials. The influence of grinding speed and time, heat treatment time, and starting materials on the structure of LiNiO2 was studied. The as-milled samples and products were characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD). The results show that uniform as-milled samples can be obtained at grinding speed of 580 rpm for 0.5 h, using LiOH and Ni(OH) 2 as raw materials. Perfect crystal LiNiO2 has been prepared by calcining the as-milled samples at 700 °C for 15 h. Composite material powders consisting of Li2 Ni8 O10 and LiNiO2 have been obtained using Li2 CO3 as lithium source.

8

Reference Abstract Domains and Applications to String Analysis

Amadini R., Gange G., Gauthier F., Jordan A., Schachte P., Søndergaard H., Stuckey P. J., Zhang C.

Fundamenta Informaticae

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2018

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Vol. 158, nr 4

297--326

EN

Abstract interpretation is a well established theory that supports reasoning about the run-time behaviour of programs. It achieves tractable reasoning by considering abstractions of run-time states, rather than the states themselves. The chosen set of abstractions is referred to as the abstract domain. We develop a novel framework for combining (a possibly large number of) abstract domains. It achieves the effect of the so-called reduced product without requiring a quadratic number of functions to translate information among abstract domains. A central notion is a reference domain, a medium for information exchange. Our approach suggests a novel and simpler way to manage the integration of large numbers of abstract domains. We instantiate our framework in the context of string analysis. Browser-embedded dynamic programming languages such as JavaScript and PHP encourage the use of strings as a universal data type for both code and data values. The ensuing vulnerabilities have made string analysis a focus of much recent research. String analysis tends to combine many elementary string abstract domains, each designed to capture a specific aspect of strings. For this instance the set of regular languages, while too expensive to use directly for analysis, provides an attractive reference domain, enabling the efficient simulation of reduced products of multiple string abstract domains.

9

Magnetohydrodynamic Calculation on Double-Loop Channel Induction Tundish

Yue Q., Pei X., Zhang C., Wang X.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 1

329--336

EN

A mathematical model is developed to investigate the electromagnetic induction heating in a continuous casting tundish with the double-loop inductor. Maxwell’s equations are solved using finite element method to obtain the magnetic flux density, electromagnetic force, and Joule heating. Results show that the induced current through the two channels generates a current loop. The electromagnetic force points to the center of the channel, thus generating a pinch effect on the molten steel. With the skin effect and proximity effect, Joule heating rate reaches its maximum and minimum values at the corners and the center of the crosssection area respectively. Power ampere-turn has a significant influence on the electromagnetic force and Joule heating density. As ampere-turns vary from 3.6×104 to 2.16×105, Joule heating rate increases from 2.4 MW m-3 to 85 MW m-3. Electromagnetic force also increases from 8×104 N m-3 to 3×106 N m-3 in the center axis line of the channel. The present work reveals the relationship between magnetic flux density and electromagnetic force. The results will be helpful in adjusting the electromagnetic field in channel-induction furnaces and modifying the design of channel parameters.

10

Generating Porosity Spectrum of Carbonate Reservoirs using Ultrasonic Imaging Log

Zhang J., Nie X., Xiao S., Zhang C., Zhang C., Zhang Z.

Acta Geophysica

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2018

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Vol. 66, no. 2

191--201

EN

Imaging logging tools can provide us the borehole wall image. The micro-resistivity imaging logging has been used to obtain borehole porosity spectrum. However, the resistivity imaging logging cannot cover the whole borehole wall. In this paper, we propose a method to calculate the porosity spectrum using ultrasonic imaging logging data. Based on the amplitude attenuation equation, we analyze the factors affecting the propagation of wave in drilling fluid and formation and based on the bulk-volume rock model, Wyllie equation and Raymer equation, we establish various conversion models between the reflection coefficient β and porosity φ. Then we use the ultrasonic imaging logging and conventional wireline logging data to calculate the near-borehole formation porosity distribution spectrum. The porosity spectrum result obtained from ultrasonic imaging data is compared with the one from the microresistivity imaging data, and they turn out to be similar, but with discrepancy, which is caused by the borehole coverage and data input difference. We separate the porosity types by performing threshold value segmentation and generate porosity-depth distribution curves by counting with equal depth spacing on the porosity image. The practice result is good and reveals the efficiency of our method.

11

Application of Multiboost-KELM algorithm to alleviate the collinearity of log curves for evaluating the abundance of organic matter in marine mud shale reservoirs: a case study in Sichuan Basin, China

Zhu L., Zhang C., Zhang C., Zhou X., Wang J., Wang X.

Acta Geophysica

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2018

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Vol. 66, no. 5

983--1000

EN

The total organic carbon (TOC) content reflects the abundance of organic matter in marine mud shale reservoirs and reveals the hydrocarbon potential of the reservoir. Traditional TOC calculation methods based on statistical and machine learning have limited effect in improving the computational accuracy of marine mud shale reservoirs. In this study, the collinearity between log curves of marine mud shale reservoirs was revealed for the first time, which was found to be adverse to the improvement of TOC calculation accuracy. To this end, a new TOC prediction method was proposed based on Multiboost-Kernel extreme learning machine (Multiboost-KELM) bridging geostatistics and machine learning technique. The proposed method not only has good data mining ability, generalization ability and sound adaptivity to small samples, but also has the ability to improve the computational accuracy by reducing the effect of collinearity between logging curves. In prediction of two mud shale reservoirs of Sichuan basin with proposed model, the results showed that the predicted value of TOC was in good consistence with the measured value. The root-mean-square error of TOC predicting results was reduced from 0.415 (back-propagation neural networks) to 0.203 and 1.117 (back-propagation neural networks) to 0.357, respectively; the relative error value decreased by up to 8.9%. The Multiboost-KELM algorithm proposed in this paper can effectively improve the prediction accuracy of TOC in marine mud shale reservoir.

12

Simultaneous determination of eight kinds of gingerols in zingiberis rhizome collected from different areas of China

Wang Y., Chen J., Li Y., Li P., Iqbal J., Chen Y., Ma Y., Zhang C.

Acta Chromatographica

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2018

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Vol. 30, no. 3

164--168

EN

A reliable and rapid high-performance liquid chromatography coupled with diode array detector method (HPLC–DAD) was established and validated to determine eight gingerol simultaneously in the rhizomes of Zingiber offcinale Rosc. The separation of eight compounds (4-hydroxy-3-methoxy-benzenebutanol,3,5-dihydroxy-1-(4-hydroxy-3-methoxyphenyl) decane, 3,5-dihydroxy-1-(3,4-dimethoxyphenyl) decane, 6-gingerol, 8-gingerol, 6-shogaol, 5-hydroxy-1-(4-hydroxy-3-methoxyphenyl)-1,4-decadien-3-one, and 10-gingerol) were performed on an Agilent TC(2) C18 (250 mm × 4.6 mm, 5 μm) at 30 °C using acetonitrile (A) and 1% formic acid aqueous solution (B) as the mobile phase with gradient elution (0–10 min, 20%–35% A; 10–28 min, 35%–55% A; 28–35 min, 55%–60% A; 35–55 min, 60%–70% A; 55.01–60 min, 100%–100% A). The detection wavelength was set at 280 nm, and the flow rate was 0.8 mL/min. Validation of the analytical method was performed by linearity, precision, and accuracy test. All compounds were quantified with good linear calibration curves (coefficient of determination R2, >0.9999). The method showed good precision with overall coefficients of variation between 0.56% and 0.84%. The range of recovery was from 95.50% to 104.14% for the analytes. This method was successfully applied to quantify eight gingerols in Z. offcinale Rosc from different regions in China, so it can provide quality assessment for this medicine.

13

Summary of the port shoreline resource evaluation based on triangular fuzzy analytic hierarchy process

Jiang L., Tao T., Zhang C., Jiang H., Wang J.

Polish Maritime Research

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2017

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S 3

16--22

EN

Port shoreline resources are the basis of port and shipping development, and its assessment method has become one of the hot issues in port research. On the basis of constructing a reasonable index evaluation system, this paper constructs the fuzzy evaluation matrix based on the triangular fuzzy analytic hierarchy process and constructs the fuzzy evaluation matrix by using the fuzzy comprehensive evaluation method, and obtains the maximum membership degree of the port shoreline resources. Compared with the traditional port shoreline Resource evaluation methods, the new one got more advantages in objective and quantitative. Finally, Combined with the Nanjing section of the Yangtze River as a case for verification, the results show that the model can accurately solve the problem of resource evaluation of port shoreline.

14

Role of Seed Bank in Establishment of Single and Mixed-Sowing Artificial Grasslands of Tibetan Plateau

Ma Z., Zhang C., Zhou H.-K., Yao B.-Q., Zhao X.-Q.

Polish Journal of Ecology

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2017

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Vol. 65, nr 4

334--344

EN

Artificial grassland establishment is one of the fastest and most effective ways to restore the productivity of degraded grasslands. Little is known about the effect of different types of artificial grassland establishment (i.e., single- and mixed-sowing grassland establishment with perennial grasses) on soil seed bank in degraded grassland ecosystems. Single-sowing population of a high yield species usually has a great standing biomass causing shading that may inhibit germination of seeds in soil seed bank. Thus, we hypothesized that there is higher species richness and seed density in the soil seed bank of single-sowing than mixed-sowing grasslands. Here, we investigated the soil seed bank in four-year old single-sowing and mixed-sowing and control (degraded) grasslands on the Qinghai-Tibetan Plateau. We found that the autumn seed bank of mixed-sowing grasslands had lower species richness and seed density than single-sowing grasslands, while the summer soil seed bank (persistent seed bank) showed little differences. There were differences in biomass among the three grasslands (single-sowing > mixed-sowing > control), but there was no differences in species richness of vegetation. In sum, our results of the autumn seed bank support our hypothesis. Greater above-ground biomass in single-sowing grasslands could generally cause low light availability preventing seeds in soil from germinating and support more seed output, which both may indirectly or directly result in the relatively higher species richness and seed density in the soil seed bank. Our results also suggest that artificial grasslands usually returning to native grasslands in terms of production and species composition after several years is likely due to stability of the persistent soil seed bank.

15

Microstructure and dielectric properties of La2O3 doped Ti-rich barium strontium titanate ceramics for capacitor applications

Zhang C., Chen F., Ling Z., Jian G., Li Y.

Materials Science Poland

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2017

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Vol. 35, No. 4

806--815

EN

Microstructure and dielectric properties of La2O3 doped Ti-rich barium strontium titanate ceramics, prepared by solid state method, were investigated with non-stoichiometric level and various La2O3 content, using XRD, SEM and LCR measuring system. With an increase of non-stoichiometric level, the unit cell volumes of perovskite lattices for the single phase Ti-rich barium strontium titanate ceramics increased due to the decreasing A site vacancy concentration V″A. The unit cell volume increased and then decreased slightly with the increasing La2O3 content. Relatively high non-stoichiometric level and high La2O3 content in Ti-rich barium strontium titanate ceramics contributed to the decreased average grain size as well as fine grain size distribution, which correspondingly improved the temperature stability of the relative dielectric constant. The relative dielectric constant єrRT, dielectric loss tanδRT and the maximum relative dielectric constant єrmax decreased and then increased with the increasing non-stoichiometric level. With the increase of La2O3 doping content, the relative dielectric constant єrRT increased initially and then decreased. The maximum relative dielectric constant єrmax can be increased by applying low doping content of La2O3 in Ti-rich barium strontium titanate ceramics due to the increased spontaneous polarization.

16

Relative clauses as a benchmark for Minimalist parking

Graf T., Monette J., Zhang C.

Journal of Language Modelling

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2017

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Vol. 5, No. 1

57--106

EN

Minimalist grammars have been used recently in a series of papers to explain well-known contrasts in human sentence processing in terms of subtle structural differences. These proposals combine a top-down parser with complexity metrics that relate parsing difficulty to memory usage. So far, though, there has been no large-scale exploration of the space of viable metrics. Building on this earlier work, we compare the ability of 1,600 metrics to derive several processing effects observed with relative clauses, many of which have been proven difficult to unify. We show that among those 1,600 candidates, a few metrics (and only a few) can provide a unified account of all these contrasts. This is a welcome result for two reasons: First, it provides a novel account of extensively studied psycholinguistic data. Second, it significantly limits the number of viable metrics that may be applied to other phenomena, thus reducing theoretical indeterminacy.

17

Comparative experiment study on nitrogen injection and free desorption of methane-rich bituminous coal under triaxial loading

Zhang L., Ye Z., Tang J., Hao D., Zhang C.

Archives of Mining Sciences

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2017

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Vol. 62, no. 4

911--928

EN

As a kind of associated geological gas, coalbed methane (CBM) is mainly adsorbed in the coal seam. The coal-methane adsorption phenomenon can be described by Langmuir monolayer adsorptio n model, BET multilayer adsorption model and the Theory of Volume Filling of Micropore (TVFM), whereas the binary gas adsorption phenomenon can be described by the extended Langmuir Model. For the CBM in the low permeability coal seam, the amount of gas released by direct drainage is relatively limited, which cannot eliminate the gas explosion and outburst hazards. Gas injection is an effective method to promote methane drainage. In this paper, the free desorption and nitrogen injection displacement experiments are comparatively analyzed, which allows verifying the effectiveness of nitrogen injection’s enhancement to gas drainage. The experiment of injecting nitrogen gas into the coal body shows that the coal fracture can be maintained or expanded by the injected gas pressure so that more methane can be released. The nitrogen injection has a higher time efficiency than that of free desorption as well. The displacement ratio of N2/CH4 is in the range of 1-3. Both the injection pressure and confining pressure affect the displacement ratio. The analysis of the desorbed gas components shows that the relationship between the methane component and gas flooding time is an “inverted S” shape curve, and the appropriate time for the methane collection can be inferred by the time interval of the rapid decline of the curve.

PL

Metan zawarty w złożu węgla występuje w głównej mierze w postaci zaadsorbowanej, jako gaz związany. Zjawisko adsorpcji metanu na węglu opisuje model adsorpcji jednowarstwowej Langmuira, model adsorpcji wielowarstwowej BET oraz teoria objętościowego wypełniania mikroporów. Z kolei procesy desorpcji mieszanin dwóch gazów opisuje rozszerzony model Langmuira. W przypadku metanu zawartego w złożu węgla o niskiej przepuszczalności, ilość gazu uwalnianego poprzez proste odgazowanie jest ograniczona i wciąż nie eliminuje ryzyka wybuchu gazu oraz wyrzutu skał i gazu. Wstrzykiwanie gazów jest jedną ze skutecznych metod odgazowania. W pracy tej przeprowadzono badanie porównawcze rezultatów swobodnej desorpcji gazu oraz wstrzyknięcia do złoża azotu, w celu zademonstrowania skuteczności odgazowania poprzez wprowadzenie azotu. Eksperyment polegający na wstrzykiwaniu azotu do calizny węglowej pokazuje możliwość zachowania lub powiększenia pęknięć w strukturze węgla pod działaniem ciśnienia wstrzykiwanego gazu, co umożliwi uwolnienie większych ilości metanu. Ponadto, wprowadzenie azotu okazuje się rozwiązaniem skuteczniejszym w dłuższym okresie czasu niż swobodna desorpcja. Stosunek wypierającego metan N2 do CH4 wynosi w przybliżeniu 1:3. Zarówno ciśnienie wstrzykiwanego gazu jak i wielkość ciśnienia złożowego mają wpływ na tempo wypierania metanu przez azot. Analiza składników desorbowanego gazu wskazuje, że zależność ilości metanu od czasu wypływu gazu opisywana jest na wykresie krzywą w postaci odwróconej litery S, zaś odpowiedni czas na odzysk metanu odczytujemy jako przedział odpowiadający nagłemu obniżeniu widocznemu na wykresie.

18

Flower Colour Polymorphism in Geranium nepalense (Geraniaceae ) : Adaptation to Non-Pollinator Agents

Tang X. X., Liu H. L., Zhang C., Wang Y., Zhang X., Yi Y.

Polish Journal of Ecology

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2016

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Vol. 64, nr 4

526--533

EN

Flower colour polymorphism is attributed to pollinator or non-pollinator mediated selection. Geranium nepalense has common white morph and very rare pink morph. We compared pollinator visitation frequencies, temperature and soil moisture between two morphs in the mixed morph population. We also compared morph ratio and reproductive success between white and pink flower individuals. Our results indicated that no visitor groups were different between two colour morphs. But visitor groups differed in visits between two years. Halictidae preferred pink morph in the year of 2012 but showed no discrimination in 2014, whereas Syrphidae preferred white morph in 2014 but no discrimination in 2012. Overall, pink morph produced more seeds than white morph, but exhibited variation between two years. However, visitor discrimination was not the main cause of the difference in female fitness. Soil moisture was not different between two colour morphs. Temperature of white morph was lower than pink in evening but not different in morning and noon. The results indicated that non-pollinator factors may exert the selective pressure to maintain the flower colour polymorphism in this species. Although pollinators did not exert selection on the flower colour polymorphism, we suggest that they provided potential pollination environment of fluctuating selection to drive flower colour evolution if visitors were limited.

19

Rare Earth Elements supply vs. clean energy technologies: new problems to be solve

Zhou B., Li Z., Zhao Y., Zhang C., Wei Y.

Gospodarka Surowcami Mineralnymi

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2016

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T. 32, z. 4

29--44

EN

Rare earth elements (REEs) provide important properties to clean energy technologies such as wind turbine and hybrid electric vehicles. The global REE demand will grow rapidly during the global transformation toward a greener economy in the next decades. This high demand will require a steady supply chain in the long run. China has a monopoly of global REE production and extraction. The global REE supply chain runs the risk of disruption along with Chinese REE policy evolution. To overcome this supply chain vulnerability, new strategies and measures should be adopted to satisfy future REE supply/demand. There is a pressing need to explore REE deposits, develop efficient REE recycling techniques from end-of-life products, improve substitution technologies for REEs, and reduce the number of critical REEs used in devices. Such measures are facing significant challenges due to environmental factors and an unbalanced market, and overcoming them requires efforts from government and REE companies.

PL

Pierwiastki ziem rzadkich (Rare Earths Elements) mają istotne znaczenie dla rozwoju czystych technologii energetycznych, takich jak turbiny wiatrowe czy pojazdy hybrydowe. Światowy popyt na REE będzie wzrastał w związku z globalną transformacją w kierunku bardziej czystej (ekologicznej) gospodarki w okresie najbliższych dziesięcioleci. Wysoki popyt wymagać będzie stabilnego łańcucha dostaw REE w dłuższej perspektywie. Chiny mają monopol w zakresie globalnej produkcji i wydobycia REE. Światowe dostawy REE obarczone są jednak ryzykiem zakłóceń wynikających z chińskiej polityki w tym zakresie. W związku z tym, powinny być przyjęte nowe środki i strategie w celu zaspokojenia przyszłego popytu/podaży na REE. Istnieje pilna konieczność: poszukiwania nowych złóż, opracowania skutecznych technik recyklingu z wycofanych z eksploatacji produktów, poprawy technologii z zastosowaniem substytutów REE oraz zmniejszenie liczby krytycznych pierwiastków ziem rzadkich w stosowanych urządzeniach. Działania te stanowią poważne wyzwanie ze względu na czynniki środowiskowe i niezrównoważony rynek (monopol podaży). Przezwyciężenie ich wymaga odpowiednich działań ze strony rządu i firm zajmujących się produkcją REE.

20

Lifetime prediction of self-lubricating spherical plain bearings based on physics-of-failure model and accelerated degradation test

Wang Y., Fang X., Zhang C., Chen X., Lu J.

Eksploatacja i Niezawodność

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2016

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Vol. 18, no. 4

528--538

EN

Due to small friction coefficient and no need for lubrication during operation, self-lubricating spherical plain bearings (SSPBs) have been widely used in operation and transmission systems in aerospace, nuclear power plants, and ship equipment and they are key components of these systems. SSPBs failure will directly affect the operational reliability and safety of the equipment; therefore, it is necessary to accurately predict the service life of SSPBs to define reasonable maintenance plans and replacement cycles and to ensure reliability and safety of vital equipment. So far, lifetime prediction of SSPB has been primarily based on empirical formulae established by most important bearing manufacturers. However, these formulae are lack of strong theoretical basis; the correction coefficients are difficult to determine, resulting in low accuracy of lifetime prediction. In an accelerated degradation test (ADT), the load is increased to accelerate the SSPB wear process. ADT provides a feasible way for accurate lifetime prediction of SSPB in a short period. In this paper, wear patterns are studied and methods of wear analysis are presented. Then, physics-offailure model which considers SSPB wear characteristics, structure parameters and operation parameters is established. Moreover, ADT method for SSPB is studied. Finally, lifetime prediction method of SSPBs based on physics-of-failure model and ADT is established to provide a theoretical method for quick and accurate lifetime prediction of SSPBs.

PL

W związku z niskim współczynnikiem tarcia oraz brakiem konieczności smarowania podczas pracy,samosmarujące łożyska ślizgowe (self-lubricating spherical bearings, SSPB) znajdują szerokie zastosowanie w układach pracy oraz układach przełożeń urządzeń w przemyśle lotniczym, elektrowniach jądrowych, oraz na statkach, stanowiąc kluczowe elementy tych układów. Uszkodzenie łożyska SSPB ma bezpośredni wpływ na niezawodność eksploatacyjną oraz bezpieczeństwo sprzętu; dlatego też istnieje konieczność precyzyjnego prognozowania resursu łożysk SSPB, pozwalającego na odpowiednie planowanie konserwacji oraz cykli wymiany , które ma na celu zapewnienie niezawodności i bezpieczeństwa kluczowego sprzętu. Dotychczas czas pracy łożysk SSPB prognozowano przede wszystkim w oparciu o wzory empiryczne podawane przez największych producentów łożysk. Wzory te, jednak, nie mają solidnej podstawy teoretycznej; trudno jest dla nich określić współczynniki korygujące, co zmniejsza trafność prognozowania czasu pracy. W przyspieszonych badaniach degradacji zwiększa się obciążenie celem przyspieszenia procesu zużycia łożysk SSPB. Badania przyspieszone umożliwiają trafne przewidywanie czasu pracy łożysk SSPB w krótkim okresie czasu. W przedstawionej pracy analizowano wzorce zużycia badanych łożysk oraz przedstawiono metody analizy zużycia. Następnie opracowano model fizyki uszkodzeń, który uwzględnia charakterystyki zużycia, parametry konstrukcyjne oraz parametry eksploatacyjne omawianych łożysk ślizgowych. Ponadto rozpatrywano możliwość zastosowania badań przyspieszonych dla tego typu łożysk. W wyniku przeprowadzonych badań, opracowano metodę prognozowania czasu pracy łożysk SSPB opartą na modelu fizyki uszkodzeń oraz badaniach przyspieszonych, która pozwala na szybkie i trafne prognozowanie czasu pracy samosmarujących łożysk ślizgowych.