ARTICLE | doi:10.20944/preprints202311.0843.v1
Online: 13 November 2023 (16:52:14 CET)
Aim at a better understanding of the flow field around a fully appended Joubert BB2 submarine model and complementing the experimental investigations of the wake of the hydroplanes and sail, the Large eddy simulation (LES) with the dynamic Smagorinsky model is conducted. Three sets of grids with a maximum grid number of up to 228 million are designed, to perform the LES simulation for the Joubert BB2 at 10° yaw conditions, with a freestream Reynolds (Re) number based on the local freestream velocity and the hull length of ReL=2.2×107. And comparison of the wake of the cruciform appendage is made with experiments, to verify the computational accuracy and examine the influence of the spatial resolution. A satisfactory result shows more favorable agreement with experimental measurements as the improvement of spatial resolution, with the relative error of the vortice centers well within 7.2% in the most refined grid arrangement. And under this grid arrangement, the evolution characteristics of three co-rotating vortices originating from the cruciform appendage are further described in detail at straight ahead and 10° yaw conditions.
ARTICLE | doi:10.20944/preprints202307.0023.v1
Subject: Social Sciences, Political Science Keywords: group panic buying incidents; evolutionary mechanisms; evolutionary game; strategy equilib-rium; simulation
Online: 3 July 2023 (08:40:03 CEST)
With the global outbreak of COVID-19, the panic buying incidents triggered by the variants of the Omicron strain have severely affected the normal social order. This paper considers the complex interest game and interactive relationship among multiple subjects in the mass panic buying event caused by rumors and constructs a three-party evolution game model of local government, rumor-monger, and public. Based on the theory of evolution game, the evolutionary process of the strategy selection of game subjects is studied, and the strategy selection of the three-game subjects under different scenarios is compared and analyzed. Taking the example of the montmorillonite powder panic buying caused by the XBB virus strain rumor in China, the evolutionary game model constructed in this study is simulated and analyzed. The study shows that: the evolution process of the mass panic buying event is characterized by six stages: the initial stage E1(0,0,0); the outbreak stage E3(0,1,0);the spread stage E7(0,1,1);the climax stage E8(1,1,1);the relief stage E5(1,1,0);and the recovery stage E4(1,0,0); there are four stable points in the evolutionary game of the three game subjects, namely (no intervention, no rumor, no panic buying), (no intervention, rumor, no panic buying), (intervention, no rumor, no panic buying), and (intervention, rumor, no panic buying), and the strategy of government intervention will be adjusted according to the strategy selection of the public and the rumor-monger; under the mechanism of reward and punishment of the higher-level government, increasing the punishment and reward intensity of the higher-level government will promote the local government to intervene in the rumor-mongering event faster, but increasing the reward intensity has a more significant impact on the intervention behavior of the local government than punishment, and increasing punishment intensity has a more significant impact on the non-rumor-mongering behavior of the rumor-monger than reward; the parameters of social risk-bearing cost, risk transmission coefficient, rumor-mongering income and cost, and public drug purchase cost have different degrees of influence on the evolutionary behavior of game subjects. This study provides new ideas for effectively responding to mass panic buying events in the context of public emergencies.
ARTICLE | doi:10.20944/preprints202305.1427.v1
Subject: Engineering, Safety, Risk, Reliability And Quality Keywords: chemical enterprises; safety regulation; evolutionary game; evolutionary stable strategy
Online: 19 May 2023 (10:16:29 CEST)
Chemical safety is related to public health, safety and environmental concerns, and the dangerous chemicals safety problem is becoming the one that people commonly pay attention to. Strengthening chemical safety supervision not only involves safe production, but also is an important link to maintain social safety. Most related studies focus on chemical safety under normal regulation, this paper addresses the perspective of ‘special rectification’ and ‘normal regulation’, and establishes an evolutionary game model between chemical enterprises and government supervision departments under different supervision modes. Based on the evolutionary game theory, this paper studies the evolution process of the two game players' strategy choices, and compares and analyzes the evolution, stability and equilibrium between the chemical safety and the behavior strategies of government regulatory departments. The model is effectively analyzed based on numerical simulation, and the results show that: Under the ‘special rectification’ mode, the strategic choice of chemical enterprises engaging in safety without investment depends on the difference between the benefits and costs of safety without investment; In the ‘normal regulation’ mode, the choice of its safety non-investment strategy depends on the difference between the cost of engaging in safety investment and the cost of safety non-investment; Increasing the government's punishment will encourage chemical enterprises to take safety investment behavior under the two supervision modes. Increasing the punishment has a significant impact on the safety investment behavior of chemical enterprises under the ‘normal regulation’ mode, but it has no significant impact on the behavior of chemical enterprises under the ‘special rectification’ mode. At the same time, increasing the punishment will inhibit the strict supervision behavior of the government. The research conclusion provides important decision support for government departments to effectively supervise the safety production of chemical enterprises.
ARTICLE | doi:10.20944/preprints202311.0180.v1
Subject: Biology And Life Sciences, Animal Science, Veterinary Science And Zoology Keywords: sheep oocytes; antral follicle; single-cell transcriptomics; molecular signatures; signaling pathways
Online: 2 November 2023 (14:40:47 CET)
The development of the ovarian antral follicle is a complex, highly regulated process. Oocytes orchestrate and coordinate the development of mammalian ovarian follicles, and the rate of follicular development is governed by a developmental program intrinsic to the oocyte. Characterizing oocyte signatures during this dynamic process is critical for understanding oocyte maturation and follicular development. Although the transcriptional signature of sheep oocytes matured in vitro and preovulatory oocytes have been previously described, the transcriptional changes of oocytes in antral follicles have not. Here, we used single-cell transcriptomics (SmartSeq2) to characterize sheep oocytes from small, medium, and large antral follicles. We characterized the transcriptomic landscape of sheep oocytes during antral follicle development, identifying unique features in the transcriptional atlas, stage-specific molecular signatures, oocyte-secreted factors, and transcription factor networks. Notably, we identified specific gene and signaling pathways in each antral follicle stage that may reflect oocyte quality and in vitro maturation competency. Additionally, we discovered key biological processes that drive the transition from small to large antral follicles, revealing hub genes involved in follicle recruitment and selection. Thus, our work provides a comprehensive characterization of the single-oocyte transcriptome, filling a gap in the mapping of the molecular landscape of sheep oogenesis. We also provide key insights into the transcriptional regulation of the critical stages of antral follicular development, which is essential for understanding how the oocyte orchestrates follicular development.
ARTICLE | doi:10.20944/preprints202012.0096.v1
Subject: Engineering, Electrical And Electronic Engineering Keywords: AHB LED constant-current driver; Digital Current-programmed control; discrete-time modeling; Modulation effect
Online: 4 December 2020 (10:09:24 CET)
The high-power Asymmetric half-bridge Converter (AHBC) LED constant current driver controlled by digital current mode is a fourth-order system. Static operating point, parasitic resistance, load characteristics, sampling effect, modulation mode and loop delay will have great influence on its dynamic performance. In this paper, the small-signal pulse transfer function of the driver is established by the discrete-time modeling method for the two operating points corresponding to the three modulation modes of the trailing edge, leading edge and double edge. And, the effects of parasitic parameters, delay effect, sampling effect and load effect are fully considered in modeling. For a large number of complex exponential matrix operations, the first order Taylor formula is used for approximate calculation after the coefficient matrix is obtained by substituting the data. Then, Matlab software is used to compare and analyze the discrete-time model and the discrete-average model. The results show that the proposed discrete-time model can more accurately characterize the resonant peak and high-frequency dynamic characteristics, and is very suitable for the design of high frequency digital controller.
ARTICLE | doi:10.20944/preprints202311.1131.v1
Subject: Chemistry And Materials Science, Surfaces, Coatings And Films Keywords: EHLA; composite coating; residual stress; wear; in-situ reaction
Online: 17 November 2023 (05:20:58 CET)
The (Ti, Nb)(C, B)/IN625 composite coating with both homogeneous and defect-free microstructure were successfully prepared by in situ on the surface of 42CrMo steel using the coupling of the ultra-high-speed laser cladding (EHLA in German) technology with the direct reaction synthesis (DRS) technology, and were comparatively analyzed with the IN625 coating prepared by the EHLA. The microstructure of the fused cladding layer was investigated by selected scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and double spherical aberration transmission electron microscopy (DSA-TEM). The residual stress distribution on both sides of the fused cladding interface was characterised by nanoindentation stress test based on the modified O&P method and the G&S energy method. The results show that the interface of (Ti, Nb)(C, B)/IN625 composite coatings is affected by about 670 kJ Joule heat released from the in-situ reaction, and the interfacial width reaches 24 μm, so that it is 6 times higher than that of IN625 coating prepared by EHLA, which effectively reduces the stress gradient in the interfacial region and alleviates the stress mismatch on both sides of the interface. However, the surface hardness of (Ti, Nb)(C, B)/IN625 composite coating is lower than that of the IN625 coating, with a value of about 240 HV0.2, and the average wear weight loss was only 10% of that of the IN625 coating, which is on the one hand attributed to the in-situ authigenic TiCB, TiC, NbMo3B4, and NbMo2B2 phases supporting the (Ti, Nb)(C, B)/IN625 composite coating substrate to achieve the abrasion reduction and wear resistance. On the other hand, it is attributed to the formation of nano-equiaxial ultrafine grains in the depth range of 250 nm below the wear surface area by the coupling of the three fields of plastic rheology-heat-force, which dynamically strengthens the wear surface.
ARTICLE | doi:10.20944/preprints202304.1079.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Sol-gel; surfactant; nanoparticles; calcium hydroxide; nano-solutions; alkali-activated materials
Online: 27 April 2023 (13:06:59 CEST)
This work presents the production and incorporation of calcium hydrolyzed nano-solutions at three concentrations (1, 2, and 3 wt.%) in alkali-activated gold mine tailings (MTs) from Arequipa, Perú. A first activator solution of sodium hydroxide (NaOH) at 10M was used. The calcium hy-drolyzed nano-solutions acted as a secondary activator and as additional calcium resource for the alkali-activated materials (AAMs) based on the low-calcium gold MTs. High-resolution trans-mission electron microscopy/energy-dispersive x-ray spectroscopy (HR-TEM/EDS) analyses were carried out to characterize the morphology, size, and structures of the calcium hydrolyzed na-noparticles. Fourier transform infrared (FTIR) analyses then were used to understand the chemical bonding interactions in the calcium hydrolyzed nanoparticles and in the AAMs. Scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS) and Quantitative X-ray diffraction (QXRD) were performed to study the structural, chemical, and phase compositions of the AAMs; uniaxial compressive tests evaluated the compressive strength of the reacted AAMs; and Nitrogen adsorption-desorption analyses measured the porosity changes at nanostructure level in the AAMs. The results indicate that each increase in the concentration of the calcium hydrolyzed nano-solution had a direct/proportional effect on the mechanical properties of the AAMs samples. The AAMs with 3 wt.% calcium-hydrolyzed nano-solution had the highest compressive strength value of 15.16 MPa, which represented an increase of 62% compared to the original system without nanoparticles and aged under the same conditions of 70°C for seven days. These results provide useful information about the positive effect of calcium-hydrolyzed nanoparticles on gold MTs and their conversion into sustainable building materials through alkali activation.