Wyniki wyszukiwania - BazTech

Ograniczanie wyników

Znaleziono wyników: 3

Liczba wyników na stronie

Wyniki wyszukiwania

Sortuj według:

Ogranicz wyniki do:

Mechanism of Ca2+/Fe3+-based synergistic activation of quartz

Liu Rongxiang, Yang Zhanfeng, Li Jie, Li Qiang, Wang Zhenjiang, Luo Xiaofeng

Physicochemical Problems of Mineral Processing

2023

Vol. 59, iss. 1

art. no. 162262

Although the flotation behaviors of iron concentrate and quartz are significantly different, quartz is the primary factor that affects the quality of iron concentrate. The flotation mechanism of quartz in the presence of mixed cationic Ca2+/Fe3+-co-activated SDS catcher was studied by conducting flotation tests with pure quartz mineral. The solution chemical calculation method, zeta potential calculation method, Fourier transform infrared (FT-IR) spectroscopy technique, X-ray photoelectron spectroscopy (XPS) technique, and other techniques were used to conduct the studies. The results showed that the maximum Ca2+/Fe3+-based synergistic activation of the flotation recovery process could be achieved in a certain range of pH values when three different activators were added sequentially. Analysis of the zeta potential values revealed that the Ca2+/Fe3+-activated quartz surface improved the extent of positive electricity generated and enhanced the SDS adsorption ability of the quartz surface. Results obtained using the FT-IR technique revealed that Ca2+/Fe3+ exerted a synergistic effect, and the adsorption process exploited the single oxygen bond interactions in the monovalent hydroxyl complex Ca(OH)+ and the double oxygen bond interactions in the Fe(OH)3 precipitates. Results obtained using the XPS technique revealed that the synergistic effect exerted by Ca2+/Fe3+ was significantly stronger than that exerted by Ca2+ or Fe3+ alone. The stable Fe-based six-membered chelate ring was formed on the surface of quartz when Fe3+ was the activator, and the chain-like Ca-based complex was formed when Ca2+ was the activator. The adsorption process on the surface of quartz proceeded following chemical as well as physical adsorption pathways. The results revealed that Ca(OH)+ and Fe(OH)3 played prominent roles during the activation of quartz surfaces in the presence of Ca2+/Fe3+.

Automated detection of abnormal respiratory sound from electronic stethoscope and mobile phone using MobileNetV2

Liao Ximing, Wu Yin, Jiang Nana, Sun Jiaxing, Xu Wujian, Gao Shaoyong, Wang Jun, Li Ting, Wang Kun, Li Qiang

Biocybernetics and Biomedical Engineering

2023

Vol. 43, no. 4

763--775

Auscultation, a traditional clinical examination method using a stethoscope to quickly assess airway abnormalities, remains valuable due to its real-time, non-invasive, and easy-to-perform nature. Recent advancements in computerized respiratory sound analysis (CRSA) have provided a quantifiable approach for recording, editing, and comparing respiratory sounds, also enabling the training of artificial intelligence models to fully excavate the potential of auscultation. However, existing sound analysis models often require complex computations, leading to prolonged processing times and high calculation and memory requirements. Moreover, the limited diversity and scope of available databases limits reproducibility and robustness, mainly relying on small sample datasets primarily collected from Caucasians. In order to overcome these limitations, we developed a new Chinese adult respiratory sound database, LD-DF RSdb, using an electronic stethoscope and mobile phone. By enrolling 145 participants, 9,584 high quality recordings were collected, containing 6,435 normal sounds, 2,782 crackles, 208 wheezes, and 159 combined sounds. Subsequently, we utilized a lightweight neural network architecture, MobileNetV2, for automated categorization of the four types of respiratory sounds, achieving an appreciable overall performance with an AUC of 0.8923. This study demonstrates the feasibility and potential of using mobile phones, electronic stethoscopes, and MobileNetV2 in CRSA. The proposed method offers a convenient and promising approach to enhance overall respiratory disease management and may help address healthcare resource disparities.

Multiples inversion imaging using a one way propagation operator

Li Qiang, Wang Deli

Acta Geophysica

2019

Vol. 67, no. 5

1341--1348

The one-way propagation operator in the frequency-space domain has the advantages of fast calculation speed and good adaptability to medium with lateral velocity variation. The full wavefeld model constructed by the one-way propagation operator is iterative. As the number of iterations increases, the components of wavefeld are more and more abundant. In the full wavefeld model, the propagation and scattering processes are independent of each other. The former is determined by the propagation operator, while the latter is determined by the scattering operator. As each iteration increases, the wavefeld component will increase by one order. As an inverse migration operator, the full wavefeld model could feed back the imaging result to the data. By calculating the residual between the simulated data and the actual data, the refectivity is updated. This is an inversion process. In this process, multiples will be imaged. In this way, the subsurface information contained in multiples is utilized and the imaging quality is greatly improved. The L1-norm is used to constrain the imaging result, which further suppresses the artifacts and improves the imaging resolution. We have made some numerical examples in 2D case, explaining the principles and advantages of this methodology.