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1

Mechanical behavior improving study of concrete deck of main beam at pylon root of composite beam cable-stayed bridge

Qi Tianyu, Wang Chao, Pan Xiang, Han Guining

Archives of Civil Engineering

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2024

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Vol. 70, nr 2

271--289

EN

Steel-concrete composite beam has been increasingly applied to large span cable-stayed bridges. It takes full advantage of the material properties of steel and concrete. However, the concrete deck bears tension in the negative moment zone, such as zero block, which is disadvantageous to structures. Aiming at this problem, a finite element model of the zero block in the negative moment zone of a semi-floating cable-stayed bridge is built, and the local mechanical performance of the bridge deck under completed status is studied. Based on the analysis results, three improvement measures have been proposed. The improvement effect of each method and composed of three methods has been studied. The numerical results show that the whole zero block zone is in the compressed state under the combined action of the bending moment and axial force of the stay cable. However, the local negative moment effect in the zero block zone is very prominent under the support of the diaphragm plate. Removing parts of the diaphragm plate at the bearing position can significantly improve local mechanical behavior in the concrete deck, which transfers the local support to the adjacent two diaphragm plates. The composed improvement effect is prominent when the three measures are adopted simultaneously.

2

Chlorella vulgaris auto-flocculation in wastewater treatment. Preface to granulation

Wang Chao, Wang Changwen, Sun Wenhui, Li Zixiang

Environment Protection Engineering

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2023

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Vol. 49, nr 1

45--56

EN

Microalgae wastewater treatment technology has not only the function of wastewater treatment but also biomass production, resource recovery, and biological carbon fixation with significant economic and environmental benefits. Good sedimentation of microalgae cells is the key to realize wastewater treatment and microalgae cell proliferation. In this study, short settling time in sequence batch reactors (SBRs) was utilizable as an environmental selection pressure to promote the auto-flocculation of Chlorella vulgaris treating synthetic domestic wastewater. After 60 days of operation, bacteria-microalgae consortia formed in the reactors, improving the settling efficiencies. Microalgae cultivation reactor with 30 min settling time had the largest flocs size and highest settling efficiency. Bacteria-microalgae granular sludge had a relatively high content of P, Fe, Mg, and Ca elements that both bacteria and microalgae coexisted and adhered to each other. The dominant bacteria distribution of bacteria-microalgae granular sludge was like that of aerobic granular sludge, which implied bacteria played a vital role in Chlorella vulgaris auto-flocculation. Lastly, the mechanism of Chlorella vulgaris auto-flocculation in wastewater treatment was interpreted.

3

Study on control of dynamic disaster induced by high-level ETHR fracture by ground fracturing

Liang Yanbo, Cheng Yuanfang, Han Zhongying, Yan Chuanliang, Liu Zhenhai, Zhang Xiufeng, Wang Chao

Acta Geophysica

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2023

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Vol. 71, no. 3

1273--1287

EN

Fracture of high-level extra thick and hard roof (ETHR) above the coal seam is the main reason for the frequent occurrence of mine dynamic disasters such as mine earthquake and rock burst. In order to address this problem, the ground fracturing technology was proposed in this paper to presplit the high-level roof. The FLAC numerical model was established to study the dynamic response of the ETHR before and after fracturing. The simulation results show that: The existence of hydraulic fracture can effectively reduce the first breaking span of ETHR, and slow down the stress and elastic deformation energy concentration of coal and rock mass on both sides of goaf. In order to ensure the economical and effective opening of prefabricated cracks, the comprehensive influence of tensile stress zone and induced stress between cracks should be fully considered in the design of crack spacing. Finally, the field test of hydraulic fracturing was carried out in 63up06 working face in Dongtan coal mine in China. The results of microseismic monitoring showed that there were only 4 strong mine earthquake events of magnitude 2.0 that happened in the first 400 m of excavation, compared with the adjacent working face, the number of large energy mining earthquake events decreased significantly. It showed that the ground fracturing effectively controlled the high and thick strata and verified the feasibility of the ground fracturing technology. The research results can provide some guidance for the treatment of mine earthquake and rock burst in similar working face.

4

Process parameter optimization and anisotropy sensitivity study for abrasive belt grinding of nickel-based single-crystal superalloy

Wang Chao, Yan Xufeng, Liao Hongzhong, Chai Linjiang, Zou Lai, Huang Yun

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 4

584--602

EN

Nickel-based single-crystal superalloys (SXs) are used as materials for aero- and industrial gas turbine blades due to their superior high-temperature strength. However, SXs have low thermal conductivity, high hardness, and high working hardening, which significantly increase the machining difficulty. Improving machining performance has been a critical aspect that influences functional performance, including the fatigue life of the blades. In this study, preliminary comparative tests were performed for abrasive belt grinding of SXs to obtain better performance in terms of surface roughness (Ra), material removal rate (MRR) and abrasive belt wear rate (Bw). Two empirical models of the process parameters of abrasive belt grinding were established using response surface methodology (RSM), and the influences of belt speed (Vs), feed speed (Vw), and normal grinding force (Fn) on Ra and MRR were analysed. The Ra and MRR were optimized with multiple responses to balance the grinding quality and efficiency based on the desirability function method. Both the percentage error of the experiments and model prediction error are within a reasonable range of 5%. In particular, three typical crystal planes ((001), (110), and (111)) were prepared and used to study the grinding performance from the perspective of anisotropy sensitivity.

5

Application of superconducting magnetic separation to an artificial mixture of chalcopyrite and molybdenite

Li Daokui, Kou Jue, Sun Chunbao, Yu Baoqiang, Wang Chao

Physicochemical Problems of Mineral Processing

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2019

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Vol. 55, iss. 3

597--604

EN

Superconducting magnetic separation of chalcopyrite and molybdenite was studied, along with the effects of the magnetic flux density, slurry concentration, and pulsation amplitude on the separation. According to the force equilibrium model of magnetic particles that accumulated on magnetic matrices during the superconducting magnetic separation, the saturated buildup of magnetic particles was calculated. The saturated buildup of magnetic particles was an approximate fan ring and had a positive correlation with the background magnetic flux density. Superconducting magnetic separation tests results showed that a Mo concentrate with a Mo grade of 31.86% and recovery of 87.24% and a Cu concentrate with a Cu grade of 30.57% and recovery of 94.76% could be obtained. This verified the feasibility of separating mixed Cu and Mo minerals via superconducting magnetic separation.

6

Low temperature synthesis of Cu0.1Co0.9Al2O4 blue ceramic pigment via the combustion method

Wang Qikun, Liu Kun, Wang Yongqing, Wang Chao, Wang Yang, Chang Qibing

Materiały Ceramiczne

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2019

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T. 71, nr 4

389--396

EN

To date, CoAl2O4 has become a crucial pigment of ceramic decoration because of the rapid development of ceramic ink-jet technology. In this work, copper ions (10 mol%) doped CoAl2O4 blue pigment has been prepared by combustion method. Different to conventional CoAl2O4 pigment synthesized at high temperature (> 1000 °C), the synthesis temperature of Cu0.1Co0.9Al2O4 blue pigment is only 700 °C. Herein, we shed light on the underlying reasons of low temperature synthesis by investigating effects of heating temperature on the phase composition, microstructure and chromatic value. This study provides a low-cost and low-energy approach to the preparation of blue ceramic pigment. Using this strategy, the addition of Co can be reduced by 10% and the synthesis temperature can be reduced by more the 300 °C.

PL

Obecnie CoAl2O4 stał się kluczowym pigmentem do dekoracji ceramicznych ze względu na szybki rozwój ceramicznej technologii druku z wykorzystaniem atramentów ceramicznych. W niniejszej pracy przygotowano metodą spalania niebieski pigment CoAl2O4 domieszkowany jonami miedzi (10% mol.). W przeciwieństwie do konwencjonalnego pigmentu CoAl2O4 syntetyzowanego w wysokiej temperaturze (1000 °C), temperatura syntezy niebieskiego pigmentu Cu0,1Co0,9Al2O4 wynosi tylko 700 °C. W tym miejscu rzucamy światło na podstawowe przyczyny syntezy niskotemperaturowej, badając wpływ temperatury ogrzewania na skład fazowy, mikrostrukturę i wartość chromatyczną. Badanie to zapewnia tanie i energooszczędne podejście do przygotowania niebieskiego pigmentu ceramicznego. Stosując tę strategię, dodatek Co można zmniejszyć o 10%, a temperaturę syntezy można obniżyć o więcej niż 300 °C.

7

Fabric Defect Detection and Classifier via Multi-Scale Dictionary Learning and an Adaptive Differential Evolution Optimized Regularization Extreme Learning Machine

Zhou Zhiyu, Wang Chao, Gao Xu, Zhu Zefei, Hu Xudong, Zheng Xiao, Jiang Likai

Fibres & Textiles in Eastern Europe

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2019

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Vol. 27, no. 1 (133)

67--77

EN

To develop an automatic detection and classifier model for fabric defects, a novel detection and classifier technique based on multi-scale dictionary learning and the adaptive differential evolution algorithm optimised regularisation extreme learning machine (ADE-RELM) is proposed. Firstly in order to speed up dictionary updating under the condition of guaranteeing dictionary sparseness, k-means singular value decomposition (KSVD) dictionary learning is used. Then multi-scale KSVD dictionary learning is presented to extract texture features of textile images more accurately. Finally a unique ADE-RELM is designed to build a defect classifier model. In the training ADE-RELM classifier stage, a self-adaptive mutation operator is used to solve the parameter setting problem of the original differential evolution algorithm, then the adaptive differential evolution algorithm is utilised to calculate the optimal input weights and hidden bias of RELM. The method proposed is committed to detecting common defects like broken warp, broken weft, oil, and the declining warp of grey-level and pure colour fabrics. Experimental results show that compared with the traditional Gabor filter method, morphological operation and local binary pattern, the method proposed in this paper can locate defects precisely and achieve high detection efficiency.

PL

W celu opracowania automatycznego modelu wykrywania i klasyfikowania defektów tkanin, zaproponowano nowatorską technikę wykrywania i klasyfikowania opartą na zastosowaniu maszyny uczącej się (ADE-RELM). Proponowana metoda ma na celu wykrywanie powszechnych defektów, takich jak przerwana osnowa i wątek oraz zabrudzenia po oleju. Wyniki eksperymentalne pokazują, że w porównaniu z tradycyjną metodą filtrów Gabora, operacją morfologiczną i lokalnym wzorcem binarnym, proponowana w artykule metoda pozwala na precyzyjne zlokalizowanie defektów i osiąga wysoką skuteczność ich wykrywania.