ARTICLE | doi:10.20944/preprints202306.1060.v1
Subject: Engineering, Civil Engineering Keywords: shield tunneling; mining method; empty pushing; structural stress; deformation characteristics; numerical simulation
Online: 14 June 2023 (14:52:30 CEST)
In the construction of shield crossing existing mined tunnel without load, it is imperative to develop corresponding design standards that reflect actual engineering force characteristics to ensure the successful completion of tunnel construction. This research uses The MIDAS-GTS finite element software to facilitate the creation of a numerical model of the shield structure for an air-push-over mine tunnel project in Changsha, China, investigating the stress field’s evolution during shield construction, and calculating the maximum positive and negative bending moments and maximum axial forces for different structures and other force states under various construction conditions. This study's findings informed the design and construction optimisation of the shield tunnelling empty-push method. The outcomes of this numerical simulation led to several key findings: (1) The soil density exerted a significantly greater impact on the internal forces of the initial support structure than both the tunnel depth and soil Poisson's ratio. Additionally, a sudden shift in internal forces occurred within the 300-350 mm range when the lining thickness was altered. (2) Factors such as the tunnel depth, soil density, soil Poisson's ratio μ, and lining thickness have a similarly influenced internal forces of the segment and the initial support. Notably, the backfill layer thickness significantly affected the segment’s maximum axial force causing an abrupt change of approximately 300 mm. (3) Under the shield machine equipment’s weight constraint, it is essential to control the guide rail’s thickness, to prevent it from becoming overly large.
ARTICLE | doi:10.20944/preprints202012.0223.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: MMR; abnormal potential method; modified Biot-Savart law; finite difference method; three-dimensional visualization simulation
Online: 9 December 2020 (12:11:59 CET)
Magnetometric Resistivity(MMR) Method, which can use the power supply method of the traditional apparent resistivity method to measure the magnetic field. At present, the application research abroad is relatively extensive, but the domestic(China) research on the application of the MMR method is very few, and it is not even well-known. This paper is based on the MMR theoretical method under the point source DC condition, combined with the abnormal potential method and the modified Biot-Savart law, and using the three-dimensional numerical calculation method of the finite difference method to calculate the abnormal potential field, electric field, and magnetic field on the matlab2018a platform. Calculate, realize the multi-physics simulation in the electromagnetic field through Matlab platform programming, and verify the correctness of the algorithm by the spherical anomaly model with an analytical solution. Through the visual simulation of the three-dimensional data volume of the multi-physics field in the electromagnetic field, we can better understand the response mechanism of the electromagnetic field under DC conditions and grasp their three-dimensional spatial distribution rules. It is hoped that the research in this article can help the research of MMR Personnel better use this method for exploration.
ARTICLE | doi:10.20944/preprints202107.0220.v2
Subject: Engineering, Automotive Engineering Keywords: Eddy current sensor; lift-off variation; radius measurement; peak frequency feature; multi-frequency testing
Online: 14 July 2021 (14:10:02 CEST)
This paper proposes a linear eddy-current feature to determine the radius of a metallic ball in a non-contact manner. An electromagnetic eddy-current sensor with two coils is placed co-axially to the metal ball during measurement. It is well known that the distance between the sensor and test piece (i.e. lift-off) affects eddy-current signals. In this paper, it is found that the peak frequency feature of inductance spectrum is linear to the lift-off spacing between the centre of coil and ball. Besides, the slope of peak frequencies versus lift-offs is linked to the radius of ball. The radius of metallic balls is retrieved from the experimental and embedded analytical result of the slope. Measurements have been carried out on 6 metallic balls with different radii. The radius of the metallic ball can be retrieved with an error of less than 2 %.
ARTICLE | doi:10.20944/preprints202012.0734.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: food culture; cultural regionalization; Chinese cuisines; machine learning; spatial struture
Online: 29 December 2020 (15:35:18 CET)
As a result of the influence of geographical environment and historical heritage, food preference has significant regional differentiation characteristics. However, the spatial structure of food culture represented by the cuisine culture at the regional level has not yet been explored from the perspective of geography. This study aims to explore such patterns by focusing on the restaurants of the eight most famous cuisines in Mainland China. Initially, the density based geospatial hotspot detector method is proposed to analyze and mapping the spatial quantitative characteristics of the eight major cuisines. A heuristic method for geographical regionalization based on machine learning was used to analyze spatial distribution patterns in accordance with the proportion of these cuisines in each prefecture-level city. Results show that some types of single-category cuisines have a stronger spatial concentration effect in the present, whereas others have a strong diffusion trend. In the comprehensive analysis of multicategory cuisines, the eight major cuisines formed a new structure of geographical regionalization of Chinese cuisine culture. This study is helpful to understand regional structure characteristics of food preference, and the density based hotspot detector proposed in this paper can also be used in the analysis of other type of POI data.
ARTICLE | doi:10.20944/preprints201801.0133.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: testosterone; cellulose bead; chitosan; coating; zinc ion; freeze drying; adsorbent
Online: 16 January 2018 (05:04:16 CET)
Immobilized metal ion affinity adsorbents have been widely used in separation technique to purify proteins. Due to the leakage of metal ion from the adsorbents, there is no metal ion affinity adsorbent for hemoperfusion has been applied to clinical trial. In this study, in order to prevent the leakage of Zn2+ loaded from cellulose beads based adsorbent, improve its stability and adsorption capacity for testosterone, Freeze-drying method was used to enhance the porosity of cellulose beads, improve the surface area of the cellulose beads and adsorption capacity for testosterone. Chitosan was used to coat the adsorbents for preventing the leakage of Zn2+ loaded and improve the adsorbent’s stability. Moreover, the factors affecting adsorption ability and some components in plasma were also investigated. The results indicate the adsorption ability of the adsorbent can be significantly improved by freeze-drying. After the adsorbent was coated with 0.02% chitosan solution, the highest adsorption percentage reached 48%. During adsorption, the Zn2+ concentration in plasma did not rise. In addition, the adsorption percentage for total proteins was below 15%. The results may be caused by the pore size and surface area of the adsorbent enlarged via freeze-drying, and the chitosan solution went into the pores and coated the outer and inner surface of the adsorbent. The adsorbent has a potential clinical application to remove testosterone in patients with recurrent and metastatic prostate cancer.
ARTICLE | doi:10.20944/preprints202104.0499.v1
Subject: Engineering, Automotive Engineering Keywords: fault detection; induced draft fan; multivariate state estimation technique (MSET); model update; power plant
Online: 19 April 2021 (14:36:56 CEST)
The induced draft (ID) fan is important auxiliary equipment in the thermal power plant. It is of great significance to monitor the operation of the ID fan for safe and efficient production. In this paper, an adaptive warning model is proposed to detect early faults of ID fans. First, a non-parametric monitoring model is constructed to describe the normal operation states with the multivariate state estimation technique (MSET). Then, an early warning approach is presented to identify abnormal behaviors based on the results of the MSET model. As the performance of the MSET model is heavily influenced by the normal operation data in the historic memory matrix, an adaptive strategy is proposed by using the samples with a high data quality index (DQI) to manage the memory matrix and update the model. The proposed method is applied to a 300 MW coal-fired power plant for early fault detection, and it is compared with the model without an update. Results show that the proposed method can detect the fault earlier and more accurately.
ARTICLE | doi:10.20944/preprints202310.1076.v1
Subject: Medicine And Pharmacology, Oncology And Oncogenics Keywords: Hepatocellular carcinoma (HCC); Human immunodeficiency virus (HIV); hepatitis; inflammatory cytokines; mitochondria DNA deletion
Online: 17 October 2023 (11:46:43 CEST)
Hepatocellular carcinoma (HCC) is a non-AIDS-defining cancer closely tied to the chronic HIV infection and associated with the release of inflammatory cytokines, immune system dysfunction, and genetic alterations within mitochondria. However, our understanding of how these factors contribute to HCC risk in PLWH is limited. The objective of the study was to ascertain the differential secretion of cytokines and mitochondria DNA (mtDNA) deletion in PLWH, and individuals diagnosed with HCC without HIV. A cross-sectional study was conducted with PLWH and HCC participants from the Korle-Bu Teaching Hospital. Plasma and peripheral blood mononuclear cells (PBMCs) were isolated from whole blood. The plasma samples were used to measure cytokines using ELISA and Luminex techniques. We determined mtDNA deletions from PBMCs. We found that the secretion of the cytokines TGF-β, FGF-2, IL-8, TNF-α, VEGF, and RANTES implicated in the pre-cancer, initiation, and early stages of HCC were similar in PLWH compared to HCC participants without HIV. PBMCs of PLWH exhibited high mtDNA deletion (60%) comparable to HCC participants without HIV (64%). These findings underscore the underlying risks associated with HCC development in PLWH. There is a need for HCC surveillance among PLWH and these cytokines could be used as biomarkers.