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1

The impact of changes in pore structure on the compressive strength of sulphoaluminate cement concrete at high temperature

Tchekwagep J. J. K., Zhao P., Wang S., Huang S., Cheng X.

Materials Science Poland

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2021

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Vol. 39, No. 1

75--85

EN

The internal pore structure of sulphoaluminate cement concrete (SACC) significantly affects its mechanical properties. The main purpose of this study was to establish the relationship between pore structure changes and compressive strength after exposure to elevated temperatures. SACC samples that had been cured for 12 months were dried to a constant weight and then exposed to different temperatures (100 °C, 200 °C and 300 °C), after which the compressive strength and pore structure were measured. The pore structure of SACC was quantitatively described by mercury intrusion porosimetry (MIP) and nitrogen adsorption results. The results showed that with increased temperature, the porosity of the SACC samples also increased and the pore structure was gradually destroyed. Moreover, the SACC’s compressive strength gradually decreased with increasing temperature. The relationship between compressive strength and porosity was in close agreement with the compressive strength–porosity equation proposed by Schiller. Therefore, after extensive exposure to elevated temperature, the changes in SACC’s compressive strength can be quantitatively described by the Schiller equation.

2

The effect of the amorphous content of laser cladding Ni-Nb-Zr/CaF2 on microstructure and properties

Liang X., Cheng Y., Cheng X., Jiang Y., Kulik T., Ferenc J.

Journal of Machine Construction and Maintenance - Problemy Eksploatacji

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2018

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no. 4

33--40

EN

Ni-Nb-Zr/CaF2 amorphous coating was prepared on the surface of SA283GRA steel by adopting a high-power laser cladding system. The results show that the Ni-Nb-Zr/CaF2 coating obtained by laser cladding has a good metallurgical bonding with the matrix of SA283GRA and the amorphous phase was obtained. The different amorphous content was obtained with varied laser power. With the increase of laser power, the dilution rate of the coating gradually increases, the amorphous phase content in the cladding coating decreased gradually, and crystallization near the substrate is significant in the laser coating. As the cladding coating is far from the substrate, the content of amorphous phase increases gradually, and the cladding coating has high thermal stability. The hardness of the Ni-Nb-Zr/CaF2 amorphous coating prepared by a laser power of 4 kW is up to the highest value of 890 HV, which is about 4.7 times that of the base material. The electrochemical corrosion results show that the corrosion resistance of the amorphous layer is better than that of the substrate in NaCl solution with 3.5% corrosive medium. The Ni-Nb-Zr/CaF2 laser coating has a relatively strong amorphous forming ability.

PL

Amorficzną powłokę Ni-Nb-Zr/CaF2 otrzymano na powierzchni stali SA283GrA metodą natryskiwania laserowego, z wykorzystaniem laserów dużej mocy. Uzyskane wyniki badań wykazały, że powłoka Ni-Nb-Zr/CaF2 charakteryzuje się dobrą przyczepnością do podłoża stalowego SA283GrA, a faza amorficzna jest otrzymywana w strefie przypowierzchniowej. Wykazano, że moc wyładowania laserowego istotnie wpływa na zawartość fazy amorficznej. Wraz ze wzrostem mocy lasera zawartość fazy amorficznej w strefie przypowierzchniowej zmniejsza się stopniowo, a stopień krystalizacji powłoki w pobliżu podłoża wzrasta. Zawartość fazy amorficznej zwiększa się gradientowo w funkcji odległości od podłoża. Największą twardość powłoki amorficznej Ni-Nb-Zr/CaF2 890 HV uzyskano z wykorzystaniem lasera o mocy 4kW, tj. ≈4,7 razy większą w stosunku do materiału podłoża. Wyniki badań odporności korozyjnej metodą elektrochemiczną wykazały, że w roztworze NaCl z 3,5% odporność na korozję strefy przypowierzchniowej zawierającej fazę amorficzną jest większa niż odporność korozyjna podłoża. Wykazano również, że faza amorficzna Ni-Nb-Zr/CaF2 ma stosunkowo dużą zdolność do formowania się w strefie przypowierzchniowej i charakteryzuje się dużą stabilnością temperaturową.

3

Kinetics of photoelectrocatalytic degradation of diclofenac using N, S co-doped TiO2 nano-crystallite decorated TiO2 nanotube arrays photoelectrode

Cui Y., Deng X., Ma Q., Zhang H., Cheng X., Li X., Xie M., Cheng Q., Li B.

Environment Protection Engineering

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2018

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Vol. 44, nr 2

117-130

EN

As a non-steroidal anti-inflammatory drug, diclofenac, was commonly used as analgesic, antiarthritic and antirheumatic, and has frequently been detected in municipal wastewater treatment plants (MWTPs) effluents and demonstrated to be potentially environmental risk on human beings. In the present study, N, S co-doped TiO2 nano-crystallites decorated TiO2 nano-tube arrays (N, S-TiO2 NCs/TiO2 NTAs) photoelectrode was used to degrade diclofenac containing wastewater. In addition, the effects of some critical parameters including initial pH, external positive potential, sodium sulfate concentration and initial diclofenac concentration on the photoelectrocatalytic (PEC) degradation of diclofenac containing wastewater and dynamic characteristics were investigated systematically. Results showed that N, S-TiO2 NCs/TiO2 NTAs photoelectrode exhibited high PEC efficiency for the degradation of diclofenac, in which the PEC processes fitted well with the Langmuir–Hinshelwood (L–H) model. Furthermore, external additional anions such as Cl–, ClO– and NO3 – played an important role in inhibiting the degradation of diclofenac. Also, the N, S-TiO2 NCs/TiO2 NTAs photoelectrode possessed good stability for consecutive applications for degradation of diclofenac, which could potentially be utilized in wastewater treatment.

4

Multi-objective optimization of stope structure parameters in broken rock conditions using grey relational analysis

Chen S., Wu A., Wang Y., Cheng X.

Archives of Mining Sciences

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2018

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Vol. 63, no. 2

269--282

EN

In order to optimize the stope structure parameters in broken rock conditions, a novel method for the optimization of stope structure parameters is described. The method is based on the field investigation, laboratory tests and numerical simulation. The grey relational analysis (GRA) is applied to the optimization of the stope structure parameters in broken rock conditions with multiple performance characteristics. The influencing factors include stope height, pillar diameter, pillar spacing and pillar array pitch, the performance characteristics include maximum tensile strength, maximum compressive strength and ore recovery rate. The setting of influencing factors is accomplished using the four factors four levels Taguchi experiment design method, and 16 experiments are done by numerical simulation. Analysis of the grey relational grade indicates the first effect value of 0.219 is the pillar array pitch. In addition, the optimal stope structure parameters are as follows: the height of the stope is 3.5 m, the pillar diameter is 3.5 m, the pillar spacing is 3 m and the pillar array pitch is 5 m. In-situ measurement shows that all of the pillars can basically remain stable, ore recovery rate can be ensured to be more than 82%. This study indicates that the GRA method can efficiently applied to the optimization of stope structure parameters.

PL

W pracy zaproponowano nową metodę optymalizacji parametrów struktury przodka wybierkowego prowadzonego w warunkach pękania skał. Metoda opiera się na badaniach terenowych, wykorzystuje także badania laboratoryjne oraz symulacje numeryczne. Do optymalizacji parametrów struktury przodka wybierkowego prowadzonego w warunkach pękania skał dla wielu wariantów charakterystyki górotworu wykorzystano ‘szarą’ analizę relacyjną (GRA – Grey Relational Analysis). Uwzględnione czynniki wpływu to wysokość przodka, średnica filarów, rozstaw filarów, rozmieszczenie filarów oraz charakterystyki górotworu: maksymalna wytrzymałość na rozciąganie oraz ściskanie oraz uzysk rudy. Ustawienia czynników wpływu dokonano z wykorzystaniem czterech czynników i dla czterech poziomów wg metody Taguchi planowania eksperymentów; ponadto 16 eksperymentów wykonano z wykorzystaniem symulacji numerycznych. Wyniki ‘szarej’ analiza relacyjnej wskazują, że wartość efektywna dla pierwszego z czynników, czyli rozmieszczenia filarów, wyniosła 0.219. Ponadto, otrzymano następujące optymalne parametry przodka: wysokość przodka 3.5 m; średnica filarów 3.5 m, rozstęp pomiędzy filarami 3 m, rozciągłość filarów 5 m. Pomiary przeprowadzone in situ wykazały, że wszystkie filary zasadniczo powinny zachować stabilność, a uzysk rudy przekroczyć może 82%. Wyniki wskazują, że ‘szara’ analiza relacyjna może być z powodzeniem wykorzystywana do optymalizacji parametrów struktury przodka wybierkowego.

5

Dynamic response of a base-isolated concrete rectangular liquid-storage structure under large amplitude sloshing

Cheng X., Li D., Li P., Zhang X., Li G.

Archives of Civil Engineering

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2017

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Vol. 63, nr 1

33--45

EN

Considering concrete nonlinearity, the wave height limit between small and large amplitude sloshing is defined based on the Bernoulli equation. Based on Navier-Stokes equations, the mathematical model of large amplitude sloshing is established for a Concrete Rectangle Liquid-Storage Structure (CRLSS). The results show that the seismic response of a CRLSS increases with the increase of seismic intensity. Under different seismic fortification intensities, the change in trend of wave height, wallboard displacement, and stress are the same, but the amplitudes are not. The areas of stress concentration appear mainly at the connections between the wallboards, and the connections between the wallboard and the bottom.

PL

Gdy amplituda chlupotania cieczy jest zbliżona do częstotliwości drgań struktury magazynowania substancji ciekłych (CRLSS), wówczas osiągamy rezonans i możemy zaobserwować silne zjawisko nieliniowe. Szkoda jest znacznie większa niż chlupotanie o małej amplitudzie. Obecnie brak jest odpowiedniego raportu na temat badań dynamicznej odpowiedzi struktury magazynowania substancji ciekłych z wykorzystaniem betonu izolacyjnego (CRLSS) z chlupotaniem o dużej amplitudzie, a wpływ materiałów betonowych nie jest brany pod uwagę. W związku z tym, w niniejszej pracy, w oparciu o równanie Bernoulliego, otrzymano ograniczone wysokości fali o dużej amplitudzie chlupotania oraz małej amplitudzie chlupotania. Na podstawie równań Naviera-Stokesa ustanowiono matematyczny model chlupotania o dużej amplitudzie i zbadano odpowiedź sejsmiczną CRLSS podczas chlupotania o dużej amplitudzie. Rozważając równanie Bernoulliego i zadowalający stan, chlupotanie substancji ciekłej jest liniowe, a nieliniowy kwadratowy człon jest lekceważony. W stałym i płynnym interfejsie, struktura magazynowania substancji ciekłych spełnia warunki ciągłości przemieszczania i równowagi siły oddziaływań. Właściwość mechaniczna gumowego zabezpieczenia izolacyjnego została opisana w oparciu o konstytutywną relacje modelu Mooney-Rivlin.

6

Heavy Metal Contamination of Surface Water and Groundwater in and Around Gejiu Tin Mine, Southwest China

Cheng X., Qi W., Danek T., Matysek D., Huang Q., Zhao X., Zhou Z., Fang R., Zou L., Xu J.

Inżynieria Mineralna

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2016

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R. 17, nr 1

93--98

EN

Heavy metal contamination due to mining activity is a global major concern because of its potential health risks to local inhabitants. The heavy metal contamination of surface water and ground water by mining activities in Gejiu tin-polymetallic mining area, Southwest China, was studied. Surface water and ground water were sampled and analyzed using AAS for Cr6+, Cd, As, Hg, Cu, Pb, Zn, Se, Fe and Mn. Analysis of HCO3–, Cl–, SO42–, F– and NO3– in water samples was also undertaken by ion chromatography. It was shown that none of water samples exceeded the guideline of Cr6+, Se and Hg, while the contamination degree of heavy metals was Mn > Fe > Cd > Zn > Pb > As > Cu, all of which were serious contamination except mild contamination for Cu. The ground waters were polluted much worse than surface water.

PL

Zanieczyszczenie metalami ciężkimi spowodowane działalnością kopalń jest światowym problemem z powodu ryzyka utraty zdrowia przez okolicznych mieszkańców. Zbadano zanieczyszczenie wód powierzchniowych oraz wód podziemnych wywołane działalnością kopalni cyny w rejonie górniczym Gejiu, południowo-zachodnie Chiny. Pobrano próbki wody powierzchniowej oraz podziemnej i zanalizowano je ze względu na obecność Cd, As, Hg, Cu, Pb, Zn, Se, Fe oraz Mn. Analizy HCO3–, Cl–, SO42–, F– oraz NO3– w próbkach wody również zostały przeprowadzone za pomocą chromatografii jonowej. Ukazano, że żadna z badanych wód nie przekroczyła dopuszczalnych poziomów dla Cr6+, Se oraz Hg. Jednakże poziom zanieczyszczenia metali ciężkimi tj. Mn > Fe > Cd > Zn > Pb > As > Cu był wysoki, za wyjątkiem niewielkiego przekroczenia norm dla Cu. Wody podziemne były znacznie bardziej zanieczyszczone niż wody powierzchniowe.

7

The authentication of the grid monitoring system for wireless sensor networks

Cheng X., Li M.

Przegląd Elektrotechniczny

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2013

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R. 89, nr 1a

252--254

EN

With the extensive application of wireless sensor networks, security issues get more and more attention. So this paper designs a authentication program based on elliptic curve cryptosystem, that is applied to distribute network monitoring system for wireless sensor networks. According to mathematical principles and methods in elliptic curve cryptosystem, designs specific implementation process of authentication program. Finally, we analyze the practicality and effectiveness of this program in the respects of communication overhead, computational and safety.

PL

W artykule przedstawiono program weryfikacji użytkownika w sieci czujników bezprzewodowych, oparty na kryptografii krzywych eliptycznych. Algorytm dokonuje implementacji systemu weryfikacyjnego. Dokonana została analiza praktyczności i efektywności systemu.

8

Forward-Secure Identity-Based Public-Key Encryption without Random Oracles

Yu J., Cheng X., Hao R., Kong F., Fan J.

Fundamenta Informaticae

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2011

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Vol. 111, nr 2

241-256

EN

In traditional identity-based encryption schemes, security will be entirely lost once secret keys are exposed. However, with more and more use of mobile and unprotected devices, key exposure seems unavoidable. To deal with this problem, we newly propose a forward-secure identitybased public-key encryption scheme. In this primitive, the exposure of the secret key in one period doesn't affect the security of the ciphertext generated in previous periods. Any parameter in our scheme has at most log-squared complexity in terms of the total number of time periods. We also give the semantic security notions of forward-secure identity-based public-key encryption. The proposed scheme is proven semantically secure in the standard model. As far as we are concerned, it is the first forward-secure identity-based public-key encryption scheme without random oracles.

9

Effects of substrate temperature on crystallite orientation of HfO2 thin films

Wang L., Fan B., Wang Z., Cheng X., Wu Y., Chen L.

Materials Science Poland

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2009

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Vol. 27, No. 2

547--550

EN

Hafnium dioxide thin films were deposited on fused silica substrates by reactive electron beam evaporation at three different substrate temperatures. After deposition, hafnium dioxide thin films were annealed in the ambient atmosphere for two hours at 500 °C and 1000 °C, respectively. X-ray diffractometry was used to study physical characterizations of as-deposited and annealed hafnium dioxide. The experimental results showed that hafnium dioxide fabricated at various substrate temperatures had different crystallite orientations after annealing at 500 °C or 1000 °C. These facts suggest that substrate temperature influences not only the crystallization state of as-deposited hafnium dioxide but also crystallite re-orientation after annealing.

10

Nanotribological characteristics of lanthanum-based thin films on phosphorylated 3-aminopropyltriethoxysilane self-assembled monolayers

Qinlin G., Cheng X.

Materials Science Poland

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2007

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Vol. 25, No. 4

977--989

EN

Lanthanum-based thin films deposited on phosphonate 3-aminopropyltriethoxysilane (APTES) selfassembled monolayers (SAM) were prepared on a hydroxylated silicon substrate by a self-assembling process from a specially formulated solution. Chemical compositions of the films and chemical states of the elements were detected by X-ray photoelectron spectrometry. The thicknesses of the films was determined with an ellipsometer, while their morphologies and nanotribological properties were analyzed by means of atomic force microscopy. It was found that the lanthanum-based thin films showed the lowest friction and adhesion followed by APTES-SAM and phosphorylated APTES-SAM, while silicon substrate showed high friction and adhesion. Microscale scratch/wear studies clearly showed that lanthanumbased thin films were much more scratch/wear resistant than the other samples. The superior friction reduction and scratch/wear resistance of lanthanum-based thin films may be attributed to low work of adhesion of non-polar terminal groups and the strong bonding strength between the films and the substrate.

11

Science, technology and strategy for minimizing GHG emission in steel industry

Cang D., Xiong G., Zhang X., Yu Y., Cheng X., Fang C.

Zeszyty Naukowe. Inżynieria Środowiska / Politechnika Opolska

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2003

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Vol. 291, z. 4

557-562

EN

In order to minimize CO2 emission from iron and steel-making processes to abate greenhouse gas impact, the considerations and some practice of science and technology as well as its strategy completed and on going in Chinese steel industry are summarized. Two available ways for the minimizing in China so far: (1) Minimizing carbon-consumption (fossil energy-saving) in all the processes of steel industry which is the most realizable measure for reducing CO2 emission. (2) To look for new alternative reaction medium in the processes where producing more C02 like Ha in blast furnace etc and new processes for iron and steel making which discharge less CO2 . Some new ideas like macro-based measures are put forward for minimizing CO2 emission in steel industry.

12

Research, technology and current situation of iron resources diversity in Chinese steel industry

Cang D., Xiong G., Yu Y., Cheng X., Zong Y.

Zeszyty Naukowe. Inżynieria Środowiska / Politechnika Opolska

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2003

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Vol. 291, z. 4

549-555

EN

The current situation of Chinese steel industry, the multi-iron resources and its recovery as well as utilization were introduced in this paper. The main concerned research activities and technology in China were introduced as well. Some new considerations and suggestion were put forward to increase the use of various recycled iron resources and appropriate degradation of iron ore. A new suggestion was made to establish an international research center for the developing of ultra steel making process which uses more various iron resources and degradation iron ore.

13

Renewable energy and its application in China

Cang D., Zhang X., Xiong G., Cheng X., Yu Y., Zong Y.

Zeszyty Naukowe. Inżynieria Środowiska / Politechnika Opolska

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2003

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Vol. 291, z. 4

427-433

EN

The general situation of renewable energy and its application in China are introduced in this report based on the statistics data from the Chinese government which includes wind energy, hydraulic power energy, Ocean energy, geothermal energy, solar energy and the bio-mass energy (but not the utilization of tide energy, temperature difference energy in Ocean for power generation and salt concentration difference energy in Ocean for power generation). The future developing of some renewable energy in China is introduced in the report as well.