Slight Fluctuation Research Articles

Capillary rise height of sulfate in Portland-limestone cement concrete under physical attack: Experimental and modelling investigation

Capillary rise is a dominate mechanism for the subsequent salt crystallization damage on concrete structures partially exposed to sulfate bearing environments. The aim of this study is to assess the capillary rise height of sulfate (h) in Portland cement (PC) and Portland-limestone cement (PLC) concretes under physical attack. The impacts of limestone contents (0 wt%, 10 wt% and 30 wt%) and water-to-binder ratios (w/b of 0.4 and 0.6) on the pore structures and sorptive property of concrete specimens were investigated. Results show that the effects of limestone content on the capillary rise heights, pore structures and sorptivity of PLC-based concrete specimens differed from different w/b ratios, as a consequence from the competition mechanism between filler effect and dilution effect due to the incorporation of limestone. The heights of efflorescence zone in PLC-based concrete specimens were found to be closely related to their volumes of capillary pores, while those of subflorescence zone only exhibited slight fluctuation at varying compositions. The time-dependent evolution of h can be divided into two stages and almost 35.7%–46.5% of the final height were reached in the first month (the fast increase stage). The capillary rise height h predicted by the modified model demonstrated good agreements with those obtained from experiments, when compared to other prediction models.

Comparison of fertilizer use efficiency in grain production between developing countries and developed countries.

The investigation of chemical fertilization intensity (FI) and efficiency can provide basal data for decision-making in food production and environmental impact assessments of fertilization. The present study aimed to compare trends of the FI and efficiency during 1961-2018 in developed and developing countries using a simple method. The FI in China increased rapidly from approximately 5kg ha-1 in 1961 to the highest value of 282 kg ha-1 in 2014, and then decreased to approximately 231 kg ha-1 in 2018. Although the fertilizer allocation efficiency (FAE) showed a slight downward trend, a slight upward trend was observed for fertilizer integrated efficiency (FIE). FIs in India, Iran and Turkey continuously increased from 5 kg ha-1 in 1961 to 116, 49(148 in 2006),120 kg ha-1 in 2018, respectively, whereas FAEs showed a significant fluctuation around horizontal direction or downward trends and their FIEs showed a slight fluctuation downward. The FIs of Britain, Germany and France, excluding USA, increased rapidly from approximately 200-400 kg ha-1 in 1960s to peaks of 430-530 kg ha-1 in 1980s, decreasing to 150-340 kg ha-1 around 2010, and then increased to the current level of 200-350 kg ha-1 , whereas FAEs and FIEs increased rapidly. France and Germany were found to have moderate chemical fertilizer input and the highest FIE. Thus, their experiences of ecological agricultures in both countries could provide good examples for developing countries to follow. In brief, models of FAE and FIE are an easier way of reflecting fertilizer efficiencies in developed and developing countries. © 2021 Society of Chemical Industry.

Intensity-Modulated Fiber-Optic Strain Sensor Using Multimode Fiber and Microfiber Joint-Assisted Micro-Cavity Interferometer

In this paper, a novel micro-cavity based Mach-Zehnder interferometer is proposed by joint-assistance of microfiber and multimode fiber (MMF). The light field distribution is comprehensively investigated, and the quantitative beam expansion range and the length of MMF are obtained. Under the optimized fabrication parameters, a joint-assisted micro-cavity structure is experimentally completed and the axial strain tests are performed. The experimental results show that obvious intensity responses of fringes are exhibited in the range from 0 to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$300~ {\mu \varepsilon }$ </tex-math></inline-formula> , but with gradually reduced wavelength sensitivities. It is found that a near-zero wavelength drift exists in the fringe of 1589.83 nm with the intensity sensitivity of ~0.02 dB/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\mu \varepsilon }$ </tex-math></inline-formula> . Besides, the corresponding temperature response is −81 pm/°C with a slight fluctuation of ~0.003 dB/°C. Such high discrimination between axial strain and temperature brings <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 0.5~ {\mu \varepsilon }$ </tex-math></inline-formula> detection resolution and ultra-low temperature crosstalk ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 0.15~ {\mu \varepsilon }/^{ {\circ }}\text{C}$ </tex-math></inline-formula> ), simultaneously. With the merits of high sensitivity and practicality, our sensor is very promising and potential in high-precision axial-strain related engineering monitoring and sensing.

Direct genome-wide identification of G-quadruplex structures by whole-genome resequencing

We present a user-friendly and transferable genome-wide DNA G-quadruplex (G4) profiling method that identifies G4 structures from ordinary whole-genome resequencing data by seizing the slight fluctuation of sequencing quality. In the human genome, 736,689 G4 structures were identified, of which 45.9% of all predicted canonical G4-forming sequences were characterized. Over 89% of the detected canonical G4s were also identified by combining polymerase stop assays with next-generation sequencing. Testing using public datasets of 6 species demonstrated that the present method is widely applicable. The detection rates of predicted canonical quadruplexes ranged from 32% to 58%. Because single nucleotide variations (SNVs) influence the formation of G4 structures and have individual differences, the given method is available to identify and characterize G4s genome-wide for specific individuals.

Pore Fractal Characteristics of Suancigou Long-Flame Coal after Electrochemical Treatment: An Experimental Study through the Implementation of N2 Adsorption and Mercury Intrusion Prosimetry Techniques.

The application of electrochemical treatment in coal seams for enhancing coalbed methane (CBM) recovery can also decrease the risks of outburst disasters. The long-flame coal samples were electrochemically modified with 0, 1, 2, and 4 V/cm electric potential gradients, and the pore structures were measured and analyzed by combined low-temperature nitrogen gas adsorption, mercury intrusion prosimetry, and fractal theory. The experimental test results indicated that the pore volumes of macropores (>50 nm) and mesopores (2–50 nm) increased after electrochemical modification and further increased with the increase in electric potential gradient. The fractal dimensions of pores showed a decreasing trend except for the slight fluctuation of the mesopores with a size of 2–4.5 nm after modification, which indicated that the overall roughness and irregularity index of pores decreased. The evolution mechanisms of pore size distributions and their fractal dimensions were explained by the dissolution of minerals and the falling off of alkane side chains in the coal surface, which would expand and connect the pores during the electrochemical modification process. The results obtained from this work were crucial for CBM exploration via an electrochemical method.

Pyrolysis-assisted transesterification for accurate quantification of phospholipid fatty acids: Application to microbial community analysis in 1000-years paddy soil chronosequence

Phospholipid fatty acids (PLFAs) are widely used to assess soil microbial community and metabolic activity in variousenvironmentalsamples. However, the transesterification of phospholipids into PLFAs still utilize homogeneous acid/alkaline catalyst, which may increase environment risk. This study developedand validated an accurate method for the determination of PLFAs in soil utilizing pyrolysis-assisted transesterification with diatomaceous earth. The thermolysis behavior of phospholipids, optimal pyrolysis conditions, tolerance against impurities, and recyclability of porous material were evaluated. Under optimal conditions, the transesterification can complete in only 8 min, with high impurity tolerance. The repeatability (relative standard deviation (RSD) between 2.59% and 12.12%), reproducibility (RSD between 5.22% and 16.22%), and linearity (r between 0.9259 and 0.9999) were excellent. This method was applied to analyze the PLFAs to evaluate microbial community of 1000-years paddy soil chronosequences and the relationships among soil chemical properties, enzyme activities and microbial community composition. Soil microbial biomass PLFAs increased significantly over time followed by slight fluctuation at 60–1000 years, but the ratios of soil fungal to bacterial and gram-positive to gram-negative PLFAs remained constant. In addition to soil total N and organic matter, soil enzyme activities related to N cycling metabolism also positively significantly influenced microbial communities. Overall, the developed PLFAs method using pyrolysis-assisted transesterification was environmentally friendly, efficient, accurate, stable, and suitable alternative to acid/alkaline transesterification of phospholipids.

Characterizing the dynamic evolutionary behavior of multivariate price movement fluctuation in the carbon-fuel energy markets system from complex network perspective

This paper explores the dynamic evolutionary characteristics of the multivariate price movement in the carbon-fuel energy markets system by analyzing the topological features of our constructed multivariate price movement evolution network. Firstly, we find that the evolution pattern of the multivariate price movement modes of the carbon-fuel energy markets system has been generally almost fixed after a while, which suggests there exist the essential evolution laws of multivariate price movement modes. Secondly, we extract the essential evolution laws by motif analysis, showing that the transmission probability from the favorable community promoting the greenhouse gases emission reduction to the unfavorable community hindering the greenhouse gases emission reduction is not low, which could result in the occurrence of the “short-term effectiveness traps” in greenhouse gases emission reduction. Finally, we also find that when the evolution occurs within the modes with slight fluctuation of the carbon and coal price, its evolution process is favorable to greenhouse gases emission reduction. The results we obtained are totally new and open up a new perspective for market regulators in the carbon trading market.

Effects of vibration on output characteristics of shipboard PV modules

In the context of green transportation, as an important clean energy technology, PV modules applied in vehicles has attracted the attention of scholars from all over the world. The reliability of PV modules on vehicles is the premise of their effective uses. In addition to the impact of solar irradiance, temperature, dust and other factors on the PV modules, vibration is also a factor that cannot be ignored, especially for ships. Taking ship as the object, this study investigates the influence mechanism of vibration on the output characteristics of PV modules. The simulation model in the MATLAB/Simulink platform has been established, and some related experimental studies have been carried out based on the experiment platform, which can simulate ship vibration environment. The results of the simulation analysis and the experimental study all show that it is possible to lead to slight fluctuation on the output of PV modules. The vibration frequency has no obvious effect on the fluctuation of the output characteristic, and the main factor is amplitude of vibration. At the same time, the differences between direct light and scattered light are studied, and the impact effects on the output characteristics of PV modules are different. The results are useful for the effective use of PV systems in vehicles, which will promote energy conservation and emission reduction in the transportation sector.

Electron spin resonance studies of (La0.6Ln0.4)0.67Ca0.33MnO3 (Ln = La, Pr, Nd and Sm) nanoparticles at different temperatures

In this work, (La0.6Ln0.4)0.67Ca0.33MnO3 (Ln = La, Pr, Nd and Sm) nanoparticles (NPs) synthesized by sol-gel process were investigated by electron spin resonance (ESR) in the temperature range 100–330 K. At the high temperature the ESR signals of La0.67Ca0.33MnO3 (LCMO) NPs only consist of a single peak with Landé g factor of 2.0. This signal is contributed from the paramagnetic (PM) Mn ions in the LCMO NPs. With decreasing the temperature the PM resonance line is split into two resonance lines, one is ferromagnetic (FM) resonance line shifting towards low field while the other is antiferromagnetic (AFM) resonance line moving to a high field. The resonance peak-to-peak spectra linewidth, increases monotonically with decreasing the temperature owing to the strong double exchange interactions below the Curie temperature (T C). Resonance field is almost temperature independent in the PM phase whereas it drops fast at temperature below T C. Consequently, the Landé g factor in the PM region is very close to 2.0 whereas in the range of 2.17–2.47 under FM state due to the strong FM interactions. For the Pr (Nd)-doped LCMO NPs below T C, their g values are in the range of 2.04–2.18 due to the substantial reduction of the FM interactions caused by the Pr (Nd)-doping at La-site. The g values of the Sm-doped LCMO NPs exhibit a slight fluctuation around 1.88 (but smaller than 2.0) within the measured temperature due to the existence of weak magnetic interactions under the PM states.

Development Analysis on BiFeO3 Nanoparticle as Material Research in Laboratorium Area through Bibliometric using Vosviewer

Abstract: Purpose: This research aimed to conduct analysis in the research of BiFeO3 nanoparticles through bibliometric analysis techniques with computational mapping used VOSviewer application. Methodology/approach: By using the publish or perish reference management tool and the Google Scholar database's collection of research article data to obtain research data article. The search was focused on the article's title and abstract with "BiFeO3 nanoparticles" was used as the search term, and literature review method was used according to related topics. This study's research era covers the most recent 10 years (2012 to 2022) from publications in both national and international journals that Google Scholar has indexed. Results/findings: From the search result, there were 996 journal articles related to keywords. The range of journal articles searched from the Google Scholar database is the last decade (from 2012 to 2022). Limitations: This limitations of this research was focused on the development trend of BiFeO3 nanoparticle research in the last decade shows a slight fluctuation but still an uptrend from time to time. Contribution: This research is expected to provide information on research development trends during the last decade for researchers who want to conduct research, especially related to the topic of BiFeO3 nanoparticle. Keywords: 1. Bibliometric 2. BiFeO3 nanoparticle 3. Publish or Perish 4. Vosviewer

Trends of the response-relationship between net anthropogenic nitrogen and phosphorus inputs (NANI/NAPI) and TN/TP export fluxes in Raohe basin, China

The intensification of anthropogenic nitrogen (N) and phosphorus (P) inputs profoundly affects water environmental quality. Hence it is pivotal to clarify the response relationship between riverine TN/TP export and anthropogenic N/P inputs to provide strategies guidance in N/P management. Based on the variation of net anthropogenic N and P inputs (NANI/NAPI) in the Raohe basin from 1990 to 2018, we constructed the response relationship between NANI/NAPI and total nitrogen and phosphorus (TN/TP) export fluxes in the riverine, which successfully predicted N and P export at the basin scale management. We found N export ratio (ratio of TN export to NANI) increased with slight fluctuation and was mainly affected by the combined effects of Nfer (fertilizer N inputs) and Ndep (atmospheric N deposition) etc., while the decrease of P export ratio (ratio of TP export to NAPI) was mainly due to intensive retention effect of the soil and sediment induced by anthropogenic influence to P transportation process. These results indicate that the downstream aquatic systems take a high risk of increasing N load pressure and the basin systems suffer a danger from rising P load pressure. Therefore, it is recommended to concentrate more on downstream aquatic systems during the N management strategy implementation and pay closer attention to the whereabouts of P in the basin system.

Fabrication and Characterization of Iridium Oxide pH Microelectrodes Based on Sputter Deposition Method.

pH value plays an important role in many fields such as chemistry and biology; therefore, rapid and accurate pH measurement is very important. Because of its advantages in preparation, wide test range, rapid response, and good biocompatibility, iridium oxide material has received more and more attention. In this paper, we present a method for preparing iridium oxide pH microelectrodes based on the sputter deposition method. The sputtering parameters of iridium oxide are also studied and optimized. Open-circuit potential tests show that microelectrodes exhibit near-Nernstian pH response with good linearity (about 60 mV/pH), fast response, high stability (a slight periodic fluctuation of potential change <2.5 mV in 24 h), and good reversibility in the pH range of 1.00–13.00.

Mixed potential type ammonia sensor using Fe-substituted LaCoO3 sensing electrode prepared by flame spray pyrolysis

NH3 detection is of great significance for precise control of the SCR system. In this paper, mixed potential type ammonia sensor using LaCo1-xFexO3 sensing electrode, YSZ electrolyte, and Pt reference electrode was developed. LaCo1-xFexO3 sensing materials were made by flame spray pyrolysis technique, and Fe B-site substitution was implemented to enhance the sensing performance. It was observed that in the concentration range of 20–70 ppm at 475 °C, the sensor using LaCo0.9Fe0.1O3 as sensing electrode exhibited the highest sensing signal and sensitivity to ammonia among the LaCo1-xFexO3-SE sensors (x = 0, 0.05, 0.1, 0.2, 0.3). A sectional linear relationship between the response value change(ΔV) of that sensor and the logarithm of ammonia concentration within the range of 2–15 ppm and 15–70 ppm was noticed, and the sensitivities were 17.52 and 87.22 mV/decade, respectively. Its lower detection limit reached 2 ppm at 475 °C. Its excellent sensing properties are ascribed to enriched oxygen vacancies and high electrocatalytic performance of the perovskite electrode. Moreover, the sensor exhibited good selectivity against CH4, CO, NO, NO2, and good stability against oxygen and water vapor concentration fluctuation. Besides, the sensing response to 50 ppm ammonia has been tested for 22 days and only a slight fluctuation within 7 % was observed. Furthermore, the mixed potential sensing mechanism of the sensor was discussed.

Tension-compression asymmetry of stress-relaxation ageing behavior of AA2219 alloy over a wide range of stress levels

The asymmetric stress-relaxation ageing behavior of AA2219 alloy has been experimentally investigated under both tension and compression loading conditions, over a wide range of stress levels at 165 °C for 11 h, using the stress-relaxation ageing tests, room-temperature tensile tests and transmission electron microscopy observations. The relaxed stresses in tension are much larger than those in compression and this deviation mostly originates from the initial rapid reduction stage of stress relaxation. With increasing initial stress, the yield strength in tension increases monotonously, while it remains basically unchanged with only a slight fluctuation of 8 MPa in compression. The mechanisms for asymmetric deformation and strengthening are unveiled on the basis of microstructural analysis. At low initial stress region, the yield strength under compression is higher as compared with that under tension, due to the GP zones and θ'' phases with larger size and weaker stress orientation effect, leading to more stronger hindering effects on the dislocation movement. At high initial stress region, massive dislocations caused by loading and main strengthening θ′ promoted by dislocations result in the larger yield strength under tension, exhibiting an unique reversed strength asymmetry in contrast to low stress level; meanwhile, these dislocations considerably accelerate the tensile stress relaxation process. In addition, the effect of tensile and compressive stresses on precipitate variants is quantitatively discussed based on the Eshelby inclusion theory. These findings benefit the deep understanding of tension-compression asymmetry and offer the theoretical basis for stress-relaxation ageing prediction models.

Optimizing K0.5Na0.5NbO3 Single Crystal by Engineering Piezoelectric Anisotropy.

K0.5Na0.5NbO3 is considered as one of the most promising lead-free piezoelectric ceramics in the field of wearable electronics because of its excellent piezoelectric properties and environmental friendliness. In this work, the temperature-dependent longitudinal piezoelectric coefficient was investigated in K0.5Na0.5NbO3 single crystals via the Landau–Ginzburg–Devonshire theory. Results show that the piezoelectric anisotropy varies with the temperature and the maximum of deviates from the polar direction of the ferroelectric phase. In the tetragonal phase, parallels with cubic polarization direction near the tetragonal-cubic transition region, and then gradually switches toward the nonpolar direction with decreasing temperatures. The maximum of in the orthorhombic phase reveals a distinct varying trend in different crystal planes. As for the rhombohedral phase, slight fluctuation of the maximum of was observed and delivered a more stable temperature-dependent maximum and its corresponding angle θmax in comparison with tetragonal and orthorhombic phases. This work not only sheds some light on the temperature-dependent phase transitions, but also paves the way for the optimization of piezoelectric properties in piezoelectric materials and devices.

Smartphone-assisted colorimetric sensing of enzyme-substrate system using pH-responsive gold nanoparticle assembly

Gold nanoparticle (AuNP)-based colorimetric biosensors have been widely used for pH sensing and monitoring its changes. However, few AuNP-based pH sensors have been developed through the manipulation of the aggregation states of AuNPs via i-motif DNA. We herein report i-motif DNA-assisted pH-responsive gold nanoparticle assembly (termed RGA), which shows a reversible and highly sensitive response to pH variation between 6.20 and 7.40. The acidic pH triggers the disassembly of the RGA, thus converting the AuNPs from aggregation state to disperse state, which leads to a color transition from blue-purple to red. Therefore, the pH value can be estimated by naked-eye determination or UV–vis spectroscopy analysis. More significantly, the visually detectable color change is monitored using the built-in camera of a smartphone. The RGB (red, green, blue) values of the RGA solution are measured by a smartphone application (APP). Following data processing, the RGB values can be converted into pH value, providing a new strategy for the on-site and real-time pH sensing. Furthermore, the pH-induced conformation change of i-motif DNA allows the RGA to detect a slight pH fluctuation in the catalytic oxidation of glucose by glucose oxidase and the hydrolysis of urea by urease.

Analysis on academic quality and influence of Chinese Journal of Epidemiology, 2006-2019

Objective: In recent years, the editorial board and editorial department of Chinese Journal of Epidemiology have taken a series of measures to further improve the academic quality and influence of the journal. This study analyzed the citation index of Chinese Journal of Epidemiology from 2006 to 2019, and evaluated the academic quality and influence of the journal. Methods: The total citation frequency, impact factor, annual index and other citation rate etc. of Chinese Journal of Epidemiology were extracted from Chinese S&T Journal Citation Report, 2006-2019 (Expanded Edition) and Chinese S&T Journal Citation Report, 2006-2019 (Natural Science) for the analysis on academic quality and influence of the journal. Results: From 2006 to 2019, there were 241-406 articles published in Chinese Journal of Epidemiology per year. The literature selection rate over the years ranged from 66% to 100%. The total expanded citation frequency of Chinese Journal of Epidemiology increased from 3 365 in 2006 to 7 817 in 2019, and the total core citation frequency increased from 1 875 in 2006 to 5 055 in 2019 with slight fluctuation. The expanded impact factor increased from 1.566 in 2006 to 2.799 in 2019. The core impact factor increased from 0.904 in 2006 to 1.842 in 2019. The expanded annual index rose from 0.224 in 2006 to 0.741 in 2019. The core annual index rose from 0.170 in 2006 to 0.602 in 2019. Conclusion: The academic quality and influence of Chinese Journal of Epidemiology has been improved gradually and its ability to focus on hot spots and report new academic achievement has been further strengthened in recent years.

Gas pipeline event classification based on one-dimensional convolutional neural network

Pipeline block and pipeline leak may lead to serious accidents and cause huge economic losses, which have been urgent problems for gas transportation. In this work, active acoustic pulse-compression technology is first introduced to detect and locate these two anomalous events. The matched filtered signals are then normalized and input into one-dimensional convolutional neural network to achieve classification of not only pipeline block and pipeline leak but also normal event such as pipeline elbow which causes acoustic wave reflection as well. Neural network parameter optimization has also been carried out as well as the comparison with long- and short-term memory network. Experimental results demonstrate that compared with long- and short-term memory network, one-dimensional convolutional neural network has an improvement in efficiency due to the great reduction of running time. For non-aliasing pipeline events, both of the models can reach 100% classification accuracy. For aliasing pipeline events, despite the shorter time series and fewer features, the classification accuracy of one-dimensional convolutional neural network still reaches 100.00%, but that of long- and short-term memory network is only 93.89%. Furthermore, the smoothing and slight fluctuation of receiver operating characteristic curve and the high value of area under curve also verify the stability and good classification performance of the proposed trained model. Therefore, the one-dimensional convolutional neural network shows significant performance for pipeline events classification and has considerable potential and application prospect in gas pipeline safety monitoring.

Spatio-Temporal Assessment of Groundwater Potential Zone in the Drought-Prone Area of Bangladesh Using GIS-Based Bivariate Models

Groundwater is one of the most dynamic and renewable natural resources found in the earth’s crust. A spatio-temporal assessment of groundwater potential zone (GWPZ) incorporating different seasons is essential to generate detailed information of groundwater distribution to maintain sustainable management and mitigate the drought consequences. This present study aimed at developing a spatio-temporal groundwater mapping approach by considering climatic factors implementing different bivariate statistic models, namely, frequency ratio (FR), Shannon’s entropy (SE), and weights of evidence. The developed approach was applied in the drought-prone area of Bangladesh to map spatio-temporal variation of GWPZ. Eighteen (18) conditioning factors including six climatic criteria under different thematic components were used, and the produced potential maps were then categorized into five classes for illustrating the spatial view, and all of them were evaluated through the method of receiver operating characteristics considering the validation wells (30%) data. The bivariate statistics models were found highly effective for both Kharif (wet) and Rabi (dry) seasons and suggest that the northeastern part of the study area, namely Bogra, Sirajganj, Pabna, and Joypurhat districts, have adequate groundwater availability; in contrast, the western part covering Chapainawabganj, Naogaon, and Rajshahi district shows scarcity of groundwater. A slight fluctuation observed for all models indicates high availability of groundwater in the Kharif season because of different climatic factors. Besides, the area under the curve score suggests that the FR model was more accurate for both season, and conversely the SE model was found less efficient to predict GWPZ. The findings suggest that the proposed approach is highly significant in mapping spatio-temporal GWPZ to formulate sustainable management strategies and to mitigate future drought consequences.

Tribological properties and residual strength of wire rope with different strands during the interlayer-transition stage

Wear is a common phenomenon between the upper and lower ropes during the interlayer-transition stage, especially for the hoisting drum with the parallel rope groove in the ultra-deep mine. It will directly reduce the service life of ropes and threaten the safe operation of the winding hoists. In order to study the tribological properties of round strands and triangular strands during the interlayer-transition stage, a wear tester was developed. Moreover, the residual strength of the worn ropes of the strands was analyzed. Results show that the coefficient of friction (COF) of triangular strands is smaller than that of round strands. The COF of the two strands were decreased under the condition of grease lubrication. The friction temperature of both kinds of strands show a trend of “rising rapidly - slight fluctuation - tending to stability”. However, the wear morphology of round strands is more serious than triangular strands. Additionally, the breaking force of worn round strands between 45 kN and 65 kN is smaller than that of worn triangular strands, concentrated between 71 kN and 82 kN. Furthermore, the breaking force-wear depth fitting formulas for the two kinds of strands are obtained to predict the residual strength of the worn ropes.