Wyniki wyszukiwania - BazTech

1

An early warning method for a slope based on the increment ratio of anchor cable internal force

Feng Jincai, Chen Jiaxin, Li Jian, Zhang Yu, Guo Jianhua, Qiu Hongyong

Archives of Civil Engineering

|

2023

|

Vol. 69, nr 1

553--569

EN

Prestressed anchor cables are active reinforcement to improve slope stability. However, the anchoring is not a permanent guarantee of stability, and the slope retains a potential risk of instability. From the perspective of the internal force of anchor cables, a new early warning method for the safety of the slope is provided, and a slope analysis model is established. With the increase in the strength reduction factor, the internal force increment curves of anchor cables under different prestresses are obtained. The point corresponding to strength reduction factors λ1 and λ2 represents a warning point. Key conclusions are drawn as follows: (1) The internal force of an anchor cable can be used to judge the stability of the slope strengthened by a prestressed anchor cable. (2) A warning index based on the internal force increment ratio of anchor cables is established. (3) The internal force increment ratio of anchor cables eliminates the influence of the initial prestress and is convenient for engineering applications.

2

Channeling analysis of wavelet threshold processing based on K-means clustering algorithm

Gan Lixiong, Li Ming, Cai Wenyuan, Li Jian, Chen Zhanglong, Sun Jian, Deng Rui

Acta Geophysica

|

2023

|

Vol. 71, no. 5

2137--2147

EN

Through the spectrum noise logging technology, the oil field is dynamically monitored, and according to its simple logging instrument and convenient operation, the position of the outer channeling of the casing can be qualitatively judged by the abnormal noise of the measurement record, and the downhole production status of the water injection well can be accurately diagnosed. Fully grasp the problems of oil casing leakage, outer channeling and packer leakage in water injection wells, and enrich downhole operations. In this paper, the downhole noise signal data are standardized, and the K-means clustering algorithm is used to classify the downhole noise signal according to the correlation coefficient of different frequencies to obtain the low-frequency noise signal, and the low-frequency noise signal is clustered twice to obtain the channeling frequency band and the reservoir fluid frequency band. The accurate channeling frequency range is determined and conforms to the domestic and foreign research data. The channeling frequency band is processed by wavelet threshold, and the useless noise in the channeling frequency band is eliminated. The channeling noise signal curve after processing is analyzed, and the main output layers have an obvious amplitude back channeling. The K-means clustering algorithm is used to analyze the channeling frequency band, and the channeling noise is processed by wavelet threshold. It is a new noise signal curve processing method, which provides a new idea for the spectrum noise logging technology to master the problem of channeling outside the pipe in the water injection well.

3

Effects of the spatialisation of water-sounds sequences on the perception of traffic noise

Li Jian, Maffei Luigi, Pascale Aniello, Masullo Massimiliano

Vibrations in Physical Systems

|

2022

|

Vol. 33, nr 1

art. no. 2022110

EN

In the last decades, different researchers have shown the positive effects of informational masking (IM) on mitigating traffic noise perception and improving the local soundscape in urban parks. Most of these studies have tested various water sounds at different signal-to-noise ratios to optimise the selection and the sound levels to set the water sounds playback. However, less is known about the effects of the spatial distribution and movement of water sounds on the perception of the surrounding environment. Three different water-sounds sequences, and one control condition with only traffic noise, were created and used in an online experiment to investigate the role of spatialisation of water-sounds sequences. The sequences include a frontal fixed-position water sound, a two-position switching water sound and a four-position-randomised moving water sound. All of them were superimposed with a background traffic noise. Thirty-six subjects participated and answered an online questionnaire consisting of sets of items to describe the sound’s perception and feeling. The Perceived Restorativeness Scale (PRS-11) was also administered. The results have shown that introducing water-sounds sequences improves some components of the restorative qualities (Fascination and Being-Away). Moreover, different spatialisation settings of water sounds proved to modify people’s perception and feelings in different aspects, including attractiveness, smoothness, mechanicalness, stimulation, and nervousness.

4

The performance of the cutting head of the longitudinal shaft anchor excavation machine based on the fuzzy number and entropy evaluation method

Zhang Zhengqi, Zhu Zongming, Qiao Shuo, Li Jian

Mining Science

|

2022

|

Vol. 29

75--92

EN

The longitudinal shaft anchor excavation machine is a new type of excavating machinery; the cutting head directly participates in cutting work. This paper focuses on the performance parameters of the cutting head. Two variables of the cutting head are selected to study, that is, the included the alloy head clip angle and the alloy head diameter. The installation angle of the pick is 55° and the section spacing is 60 mm. Three groups of data were selected for each variable, and the ANSYS finite element analysis software was used to simulate the rock cutting of the pick, and the load characteristics of the pick were obtained. The fuzzy number principle and entropy evaluation method are used to evaluate the load fluctuation, specific energy consumption, and pick load of three groups of data in each variable, and then the optimal performance parameters of the pick are obtained. The specific work is as follows: 1. Two parameter variables of the pick are selected and analyzed by LS-DYNA simulation software to obtain the cutting load of the pick at work. 2. Determine the index set and evaluation set of the cutting head, use the fuzzy number principle and entropy evaluation method to calculate the weight of each parameter variable, create the fuzzy number relation evaluation matrix of performance parameters, and then use the fuzzy number comprehensive evaluation model to calculate the fuzzy number comprehensive evaluation result vector, finally get a set of optimal performance parameters of the pick. The final results show that the cutting head has the best performance when the alloy head clip angle is 100° and the alloy head diameter is 11 mm.

5

The preparation of CNT/PMMA composite film on SiO2 substrates

Li Jian

Materials Science Poland

|

2021

|

Vol. 39, No. 4

639--645

EN

Microelectromechanical system (MEMS) has been highly valued since the size of the MEMS structure is miniaturized, the spacing between the components is in the nanometer range, and the behaviors of friction and adhesion greatly affect the reliability of MEMS. An atomic force microscope (AFM) was used to observe the surface morphology of carbon nanotube (CNT)/polymethyl methacrylate (PMMA) film, and X-ray photoelectron spectroscopy (XPS) was used to analyze the chemical state of typical elements on the surface of the film. The friction and wear properties of composite nano-films under macroscopic conditions were systematically studied. The research results show that the composite nano-film has excellent anti-friction and anti-wear properties.