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Acoustic emissions evaluation of the dynamic splitting tensile properties of steel fiber reinforced concrete

《结构与土木工程前沿（英文）》   页码 1341-1356 doi: 10.1007/s11709-023-0988-4

摘要： This study empirically investigated the influence of freeze–thaw cycling on the dynamic splitting tensile properties of steel fiber reinforced concrete (SFRC). Brazilian disc splitting tests were conducted using four loading rates (0.002, 0.02, 0.2, and 2 mm/s) on specimens with four steel fiber contents (0%, 0.6%, 1.2%, and 1.8%) subjected to 0 and 50 freeze–thaw cycles. The dynamic splitting tensile damage characteristics were evaluated using acoustic emission (AE) parameter analysis and Fourier transform spectral analysis. The results quantified using the freeze–thaw damage factor defined in this paper indicate that the degree of damage to SFRC caused by freeze–thaw cycling was aggravated with increasing loading rate but mitigated by increasing fiber content. The percentage of low-frequency AE signals produced by the SFRC specimens during loading decreased with increasing loading rate, whereas that of high-frequency AE signals increased. Freeze–thaw action had little effect on the crack types observed during the early and middle stages of the loading process; however, the primary crack type observed during the later stage of loading changed from shear to tensile after the SFRC specimens were subjected to freeze–thaw cycling. Notably, the results of this study indicate that the freeze–thaw damage to SFRC reduces AE signal activity at low frequencies.

关键词： steel fiber reinforced concrete     freeze–thaw cycling     Brazilian disc splitting test     acoustic emission technique     dynamic splitting tensile acoustic emission properties    

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Analysis of load and adaptability of disc cutters during shield tunneling in soft–hard varied strata

《结构与土木工程前沿（英文）》 2023年 第17卷 第4期   页码 533-545 doi: 10.1007/s11709-023-0946-1

摘要： The disc cutters of shield machines exhibit unsatisfactory adaptability and performance during the soft–hard varied strata tunneling process. To analyze the rotation state, cutting performance, and adaptability of disc cutters during shield tunneling in soft–hard varied strata, the Holmquist Johnson Cook and Federal Highway Administration constitutive models are introduced to numerically simulate the failure process of materials on the excavation face and to calculate the load of disc cutters. Additionally, the parameters of the models are modified based on laboratory disc cutter excavation test results. The results of numerical calculation can reflect the load level and the behavior of the disc cutters during operation. The tangential loads of the disc cutters during the cutting of four typical soft-strata excavation face models are numerically calculated, thus providing reference values for the starting torque of the disc cutters. A greater penetration is suggested for soft-strata tunneling to allow the disc cutters to rotate smoothly and continuously as well as to guarantee a better cutting effect. The disc cutters in the center of the cutterhead should be specified with a lower starting torque to prevent uneven wear, rotation stagnation, cutterhead clogging, and other adverse phenomena.

关键词： shield tunneling     disc cutter load     laboratory excavation test     numerical calculation     soft–hard varied strata    

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Vibration analysis of blade-disc coupled structure of compressor

WANG Chunjie, SONG Shunguang, ZONG Xiao

《能源前沿（英文）》 2008年 第2卷 第3期   页码 302-305 doi: 10.1007/s11708-008-0064-8

摘要： While a 3D assembly model of blade-disc structure was established, a finite element model for calculating the vibration characteristics during blade-disc coupling was built by taking into consideration the coupling action of contact stress between the blade and the disc. The vibration characteristics of the blade-disc coupling structure was calculated and analyzed using cycle analysis method with the aid of ANSYS software. The modeling experiment shows that this method is feasible for analyzing the rabbet assembly structure.

关键词： blade-disc coupling     assembly     experiment     vibration     blade-disc structure    

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Wear mechanism of disc-brake block material for new type of drilling rig

WANG Xinhua, WANG Simin, ZHANG Siwei, WANG Deguo

《机械工程前沿（英文）》 2008年 第3卷 第1期   页码 10-16 doi: 10.1007/s11465-008-0009-2

摘要： To improve friction and wear performance and service life of the disc-brake pair material of a drilling rig, a new type of asbestos-free frictional material with better performance for disc-brake blocks is developed, and its wear mechanism is investigated by friction and wear experiments. Topography and elementary components of the brake block’s wear surface are analyzed by employing SEM and EDAX patterns, revealing its tribological behaviour and wear mechanism. When the frictional temperature is lower, the surface film of the brake block is thinner, dense, smooth with plasticity, and divided into the mixture area, Fe-abundant area, carbon-abundant area and spalling area. The mixture area consists of various constituents of frictional pairs without ploughing and rolling trace. The Fe-abundant area mainly consists of iron and other constituents. The carbon-abundant area is the zone where graphite and organic fibre are comparatively gathered, while the spalling area is the zone where the surface film is spalled and its surface is rough and uneven, with a loose and denuded state. During the period of high frictional temperature, the frictional surface is also divided into the mixture area, Fe-abundant area and spalling area. In this case, the mixture area consists of abrasive dust from friction pairs, and the surface film is distributed with crumby hard granules, exiguous oxide, carbide granules and sheared slender fibre. The Fe-abundant area is mostly an oxide layer of iron with a flaky distribution. Fracture and spalling traces as well as an overlapping structure of multilayer surface films can be easily found on the surface film. The components of the spalling area are basically the same as that of the matrix. At the beginning of wear, the hard peaks from the friction surface of the disc-brake plough on the surface of the brake block. With increasing frictional temperature, the friction surface begins to soften and expand, and oxidized wear occurs at the same time. During the high-temperature wear period, severely influenced by friction heat, obvious softening and plastic flow can be found on the friction surface of the brake block, its anti-shearing ability is weakened, and adhesive wear is intensified. Thermal decomposition of cohesive material in the brake block is simultaneously strengthened, so that constituents shed due to loss of adhesion. Organic fibre is in a flowing state and obviously generates drawing, shearing, carbonization and oxidization. In addition, thermal cracking, thermal oxidization, carbonization and cyclization of organic substances on the surface of brake block can make the friction surface produce pores or cracks, thus fatigue wear occurs.

关键词： asbestos-free frictional     Fracture     cyclization     friction     disc-brake    

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Field and laboratory experimental studies on hard-rock tunnel excavation based on disc cutter coupled

《结构与土木工程前沿（英文）》   页码 1370-1386 doi: 10.1007/s11709-023-0947-0

摘要： The tunnel boring machine (TBM) is typically used in hard-rock tunnel excavation. Owing to the unsatisfactory adaptability of TBM to the surrounding rock, when crossing high-strength and high-wear strata, the TBM can easily cause defects, such as abnormal wear on cutters and overload damage to bearings, thus affecting the construction efficiency and cost. Therefore, high-pressure waterjet technology should be applied to assist in rock breaking for efficient TBM tunneling. In this study, the effects of water pressure, nozzle diameter, and nozzle speed on cutting are investigated via laboratory experiments of cutting hard rock using high-pressure waterjets. The penetration performance of the TBM under different water pressures is investigated via a field industrial penetration test. The results show that high-pressure waterjets are highly efficient for rock breaking and are suitable for industrial applications, as they can accommodate the advancing speed of the TBM and achieve high-efficiency rock breaking. However, during the operation of high-pressure waterjets, the ambient temperature and waterjet temperature in the tunnel increase significantly, which weakens the cooling effect of the cutterhead and decreases the construction efficiency of the TBM. Therefore, temperature control and cooling measures for high-pressure waterjets during their long-term operation must be identified. This study provides a useful reference for the design and construction of high-pressure water-jet-assisted cutterheads for breaking road headers.

关键词： tunnel boring machine     hard-rock cutting     free face     disc cutter     rock-cutting efficiency    

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Effects of inclination angles of disc cutter on machining quality of Nomex honeycomb core in ultrasonic

Yidan WANG, Renke KANG, Yan QIN, Qian MENG, Zhigang DONG

《机械工程前沿（英文）》 2021年 第16卷 第2期   页码 285-297 doi: 10.1007/s11465-021-0631-9

摘要： Ultrasonic cutting with a disc cutter is an advanced machining method for the high-quality processing of Nomex honeycomb core. The machining quality is influenced by ultrasonic cutting parameters, as well as tool orientations, which are determined by the multi-axis machining requirements and the angle control of the cutting system. However, in existing research, the effect of the disc cutter orientation on the machining quality has not been studied in depth, and practical guidance for the use of disc cutters is lacking. In this work, the inclined ultrasonic cutting process with a disc cutter was analyzed, and cutting experiments with different inclination angles were conducted. The theoretical residual height models of the honeycomb core, as a result of the lead and tilt angles, were established and verified with the results obtained by a linear laser displacement sensor. Research shows that the residual height of the honeycomb core, as a result of the tilt angle, is much larger than that as a result of the lead angle. Furthermore, the tearing of the cell wall on the machined surface was observed, and the effects of the ultrasonic vibration, lead angle, and tilt angle on the tear rate and tear length of the cell wall were studied. Experimental results revealed that ultrasonic vibration can effectively decrease the tearing of the cell wall and improve the machining quality. Changes in the tilt angle have less effect than changes in the lead angle on the tearing of the cell wall. The determination of inclination angles should consider the actual processing requirements for the residual height and the machining quality of the cell wall. This study investigates the influence of the inclination angles of a disc cutter on the machining quality of Nomex honeycomb core in ultrasonic cutting and provides guidelines for machining.

关键词： Nomex honeycomb core     disc cutter     inclined ultrasonic cutting     machining quality    

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Performance of landfill leachate treatment system with disc-tube reverse osmosis units

WANG Baozhen, LIU Shuo, LIU Yanping, LI Xiujin

《环境科学与工程前沿（英文）》 2008年 第2卷 第1期   页码 24-31 doi: 10.1007/s11783-008-0024-x

摘要： Reverse osmosis system with the disc-tube module (DT-RO) was applied to treat landfill leachate on full scale at the Changshengqiao Sanitary Landfill, Chongqing City, China. In the first six-mouth operation phase, the treatment performance of DT-RO system had been excellent and stable. The removal rate of chemical oxygen demand (COD), total organic carbon (TOC), electrical conductivity (EC), and ammonia nitrogen (NH-N) reached 99.2–99.7%, 99.2%, 99.6%, and over 98%, respectively. The rejection of Ca, Ba, and Mg was over 99.9%, respectively. Suspended solid (SS) was not detected in product water. Effective methods had been adopted to control membrane fouling, of which chemical cleaning is of utmost importance to guarantee the long smooth operation of the DT-RO system. The DT-RO system is cleaned in turns with Cleaner A and Cleaner C. At present, the 1st stage cleaning cycle by Cleaner A and Cleaner C is conducted every 100 and 500 h, respectively, depending on raw the water quality.

关键词： chemical cleaning     product     organic     nitrogen     Effective    

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Best operating conditions to produce hydroxyapatite nanoparticles by means of a spinning disc reactor

A. F. D’ Intino,B. de Caprariis,M.L. Santarelli,N. Verdone,A. Chianese

《化学科学与工程前沿（英文）》 2014年 第8卷 第2期   页码 156-160 doi: 10.1007/s11705-014-1427-9

摘要： In this work, Mg doped hydroxyapatite (Mg-HAP) nanoparticles were produced by a reaction-precipitation process by using a spinning disc reactor (SDR) at high rotational speed. The production process of these nanoparticles consisted of the neutralization reaction between two aqueous solutions of calcium chloride and ammonia orthophosphate at room temperature. By operating at pH= 10, a high purity Mg-HAP nanoparticles were obtained. In particular, they were 51 nm in average size when the two reagents were fed over the disc symmetrically at 3 cm from the disc center and a rotational speed of the disc reactor equal to 1400 r/min was adopted.

关键词： hydroxyapatite     nanoparticles     spinning disc reactor    

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Generation of enhanced stability of SnO/In(OH)/InP for photocatalytic water splitting by SnO protection

《能源前沿（英文）》 2021年 第15卷 第3期   页码 710-720 doi: 10.1007/s11708-021-0764-x

摘要： InP shows a very high efficiency for solar light to electricity conversion in solar cell and may present an expectation property in photocatalytic hydrogen evolution. However, it suffers serious corrosion in water dispersion. In this paper, it is demonstrated that the stability and activity of the InP-based catalyst are effectively enhanced by applying an anti-corrosion SnO layer and In(OH)3 transition layer, which reduces the crystal mismatch between SnO and InP and increases charge transfer. The obtained Pt/SnO/In(OH)3/InP exhibits a hydrogen production rate of 144.42 µmol/g in 3 h under visible light illumination in multi-cycle tests without remarkable decay, 123 times higher than that of naked In(OH)3/InP without any electron donor under visible irradiation.

关键词： SnO/In(OH)3/InP photocatalyst     enhanced activity and stability for water splitting     corrosion inhibition     enhancing charge transfer and decreasing crystal mismatch    

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Approaching the commercial threshold of solar water splitting toward hydrogen by III-nitrides nanowires

《能源前沿（英文）》 doi: 10.1007/s11708-023-0870-z

摘要： Approaching the commercial threshold of solar water splitting toward hydrogen by III-nitrides nanowires

关键词： threshold solar water     splitting hydrogen III    

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An overview and recent advances in electrocatalysts for direct seawater splitting

《化学科学与工程前沿（英文）》 2021年 第15卷 第6期   页码 1408-1426 doi: 10.1007/s11705-021-2102-6

摘要： In comparison to pure water, seawater is widely accepted as an unlimited resource. The direct seawater splitting is economical and eco-friendly, but the key challenges in seawater, especially the chlorine-related competing reactions at the anode, seriously hamper its practical application. The development of earth-abundant electrocatalysts toward direct seawater splitting has emerged as a promising strategy. Highly efficient electrocatalysts with improved selectivity and stability are of significance in preventing the interference of side reactions and resisting various impurities. This review first discusses the macroscopic understanding of direct seawater electrolysis and then focuses on the strategies for rational design of electrocatalysts toward direct seawater splitting. The perspectives of improved electrocatalysts to solve emerging challenges and further development of direct seawater splitting are also provided.

关键词： seawater splitting     electrocatalysts     oxygen evolution reaction     hydrogen evolution reaction     chlorine chemistry    

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Adenovirus-mediated tissue inhibitor of metalloproteinase-3 gene transfection inhibits rabbit intervertebral disc

Xudong YU MM, Zengwu SHAO MD, Liming XIONG MD, Weiwei XU MM, Hezhong WANG MM, Huifa XU MM,

《医学前沿（英文）》 2009年 第3卷 第4期   页码 415-420 doi: 10.1007/s11684-009-0072-z

摘要： The aim of this study was to investigate the inhibitory effects of recombinant adenovirus vector carrying tissue inhibitor of metalloproteinase-3 (RAdTIMP-3) against degeneration of rabbit intervertebral disc. Thirty Japanese white rabbits of 4 months old were randomly divided into 5 groups. Mild or moderate rabbit lumbar disc degeneration model was constructed with the controllable axial loading device by imposing 98N pressure at the discs for 2 weeks. Various doses of virus were injected into the degenerated discs as follows: 20μL of normal saline in group 1; 20μL of RAd66 (an empty adenovirus vector, 1.0×10OPU/mL) in group 2; and 20, 10, and 5μL of RAdTIMP-3 (1.0×10OPU/mL) in groups 3, 4, and 5, respectively. Two weeks after the injection, the discs were collected for investigations, including assessment of degeneration degrees according to the Thompson’s grading system, reverse-transcription polymerase chain reaction (RT-PCR) assay for TIMP-3 gene, Safranin O-Fast green staining, and immunohistochemical staining for TIMP-3 and type II collagen. According to Thompson’s criteria, the degeneration of groups 3, 4, and 5, especially group 3, was alleviated as compared with groups 1 and 2. RT-PCR revealed that the expression of TIMP-3 in groups 3, 4, and 5, especially in group 3, was significantly enhanced as compared with group 1 (<0.01). Both Safranin O-Fast green staining and type II collagen staining demonstrated better reserved integrity of disc matrix in groups 3, 4, and 5 than in groups 1 and 2. TIMP-3 staining exhibited an obvious increase of positive-staining rate in groups 3, 4, and 5 as compared with group 1. The positive-staining rate in group 3 (79.42%±1.35%) was about 3times that of group 1 (25.47%±5.46%, <0.01). RAdTIMP-3 can effectively protect the matrix of rabbit intervertebral disc against overloading-induced degeneration in a dose-dependent manner, resulting in the alleviation of disc degeneration.

关键词： tissue inhibitor of metalloproteinase-3     intervertebral disc     rabbit     gene therapy    

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Enhanced photocatalytic water splitting with surface defective SrTiO

Junying LIU, Zhidong WEI, Wenfeng SHANGGUAN

《能源前沿（英文）》 2021年 第15卷 第1期   页码 700-709 doi: 10.1007/s11708-021-0735-2

摘要： Surface reconstructed SrTiO nanocrystals were synthesized by a thermal treatment process in presence of NaBH and SrTiO nanocrystals. The surface reconstruction of SrTiO nanocrystals is attributed to the introduction of surface oxygen vacancies or Ti sites (such as Ti and Ti ) during the hydrogenation treatment process. The light absorption and the charge transfer ability of SrTiO nanocrystals are simultaneously enhanced due to surface oxygen vacancies or Ti sites (such as Ti and Ti ), which are beneficial to photocatalytic water splitting. Meanwhile, these defects also change the redox potential of the photocatalysts. Since there existed a synergistic effect between the three, the ratio of hydrogen to oxygen production was also regulated.

关键词： SrTiO3     surface reconstruction     oxygen vacancies     photocatalytic water splitting    

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polarization enhanced bismuth ferrate photoelectrode: fabrication and boosted photoelectrochemical water splitting

《能源前沿（英文）》 2021年 第15卷 第3期   页码 781-790 doi: 10.1007/s11708-021-0782-8

摘要： In this paper, the fabrication of a highly orientated Bi2Fe4O9 (BFO) photoelectrode in the presence of two-dimensional (2D) graphene oxide (GO) was reported. It was found that the GO can be used as a template for controlling the growth of BFO, and the nanoplate composites of BFO/reduced graphene oxide (RGO) with a high orientation can be fabricated. The thickness of the nanoplates became thinner as the ratio of GO increased. As a result, the ferroelectric spontaneous polarization unit arranges itself in the space in a periodic manner, leading to the formation of a polarization field along a special direction. Therefore, the created built-in electric field of the nanoplate composites of BFO/RGO is improved upon the increase of the amount of RGO. As expected, carrier separation is enhanced by the built-in electric field, therefore substantially enhancing the photoelectrochemical (PEC) activity of water splitting compared to pure BFO under the irradiation of visible-light.

关键词： bismuth ferrate     ferroelectric polarisation     photoelectrochemical (PEC) water splitting     graphene oxide (GO)     high orientation    

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Ga(X)N/Si nanoarchitecture: An emerging semiconductor platform for sunlight-powered water splitting toward

《能源前沿（英文）》 doi: 10.1007/s11708-023-0881-9

摘要： Sunlight-powered water splitting presents a promising strategy for converting intermittent and virtually unlimited solar energy into energy-dense and storable green hydrogen. Since the pioneering discovery by Honda and Fujishima, considerable efforts have been made in this research area. Among various materials developed, Ga(X)N/Si (X = In, Ge, Mg, etc.) nanoarchitecture has emerged as a disruptive semiconductor platform to split water toward hydrogen by sunlight. This paper introduces the characteristics, properties, and growth/synthesis/fabrication methods of Ga(X)N/Si nanoarchitecture, primarily focusing on explaining the suitability as an ideal platform for sunlight-powered water splitting toward green hydrogen fuel. In addition, it exclusively summarizes the recent progress and development of Ga(X)N/Si nanoarchitecture for photocatalytic and photoelectrochemical water splitting. Moreover, it describes the challenges and prospects of artificial photosynthesis integrated device and system using Ga(X)N/Si nanoarchitectures for solar water splitting toward hydrogen.

关键词： Ga(X)N/Si nanoarchitecture     artificial photosynthesis     water splitting     solar toward hydrogen    

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标题 作者 时间 类型 操作

Acoustic emissions evaluation of the dynamic splitting tensile properties of steel fiber reinforced concrete

期刊论文

Analysis of load and adaptability of disc cutters during shield tunneling in soft–hard varied strata

期刊论文

Vibration analysis of blade-disc coupled structure of compressor

WANG Chunjie, SONG Shunguang, ZONG Xiao

期刊论文

Wear mechanism of disc-brake block material for new type of drilling rig

WANG Xinhua, WANG Simin, ZHANG Siwei, WANG Deguo

期刊论文

Field and laboratory experimental studies on hard-rock tunnel excavation based on disc cutter coupled

期刊论文

Effects of inclination angles of disc cutter on machining quality of Nomex honeycomb core in ultrasonic

Yidan WANG, Renke KANG, Yan QIN, Qian MENG, Zhigang DONG

期刊论文

Performance of landfill leachate treatment system with disc-tube reverse osmosis units

WANG Baozhen, LIU Shuo, LIU Yanping, LI Xiujin

期刊论文

Best operating conditions to produce hydroxyapatite nanoparticles by means of a spinning disc reactor

A. F. D’ Intino,B. de Caprariis,M.L. Santarelli,N. Verdone,A. Chianese

期刊论文

Generation of enhanced stability of SnO/In(OH)/InP for photocatalytic water splitting by SnO protection

期刊论文

Approaching the commercial threshold of solar water splitting toward hydrogen by III-nitrides nanowires

期刊论文

An overview and recent advances in electrocatalysts for direct seawater splitting

期刊论文

Adenovirus-mediated tissue inhibitor of metalloproteinase-3 gene transfection inhibits rabbit intervertebral disc

Xudong YU MM, Zengwu SHAO MD, Liming XIONG MD, Weiwei XU MM, Hezhong WANG MM, Huifa XU MM,

期刊论文

Enhanced photocatalytic water splitting with surface defective SrTiO

Junying LIU, Zhidong WEI, Wenfeng SHANGGUAN

期刊论文

polarization enhanced bismuth ferrate photoelectrode: fabrication and boosted photoelectrochemical water splitting

期刊论文

Ga(X)N/Si nanoarchitecture: An emerging semiconductor platform for sunlight-powered water splitting toward

期刊论文