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Rate of the phase transition for a charged anti-de Sitter black hole

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Science China(Physics,Mechanics & Astronomy) 2023年第4期66卷 61-66页

作者： zhen-ming xu Bin Wu Wen-Li Yang School of Physics Northwest UniversityXi'an 710127China Institute of Modern Physics Northwest UniversityXi'an 710127China Shaanxi Key Laboratory for Theoretical Physics Frontiers Xi'an 710127China Peng Huanwu Center for Fundamental Theory Xi'an 710127China

Phase transition is a core content of black hole thermodynamics. This study adopted Kramer’s escape rate method for describing the Brownian motion of particles in an external field to investigate the intensity of the phase transition between small and large black hole states. Some existing studies mostly focused on the formal analysis of the thermodynamic phase transition of black holes, but they neglected the detailed description of the phase transition process. Our results show that the phase transition between small and large black holes for charged anti-de Sitter(AdS) black holes presents serious asymmetric features, and the overall process is dominated by the transition from a small black hole to a large black hole. This study filled a research gap of a stochastic process analysis on the issue of the first-order phase transition rate in the Ad S black hole.

关键词： black hole thermodynamics phase transition thermal potential Kramer’s escape rate

Interaction potential and thermo-correction to the equation of state for thermally stable Schwarzschild anti-de Sitter black holes

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Science China(Physics,Mechanics & Astronomy) 2019年第1期62卷 27-31页

作者： Yan-Gang Miao zhen-ming xu School of Physics Nankai University

The microscopic structure of black holes remains a challenging subject. In this paper, based on the well-accepted fact that black holes can be mapped to thermodynamic systems, we make a preliminary exploration of the microscopic structure of the thermodynamically stable Schwarzschild anti-de-Sitter(SAdS) black hole. In accordance with the number density and thermodynamic scalar curvature, we give the interaction potential among the molecules of thermodynamically stable SAdS black holes and analyze its effectiveness. Moreover, we derive the thermo-correction to the equation of state for such black holes that arises from interactions among black-hole molecules using virial coefficients.

关键词： molecular potential number density equation of state

Design Research of a Novel Aftercool-Humidifier Concept for Humid Air Turbine Cycle

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Journal of Thermal Science 2024年第3期33卷 951-969页

作者： ZHANG Junzheng xu zhen School of Energy and Power Engineering Shandong UniversityJi’nan250061China Shandong Engineering Laboratory for High-efficiency Energy Conservation and Energy Storage Technology&Equipment Shandong UniversityJi’nan250061China

Humid air turbine cycle(HAT)has potential of electrical efficiencies comparable to combined cycle,with lower investment cost and NO_(x) *** typical heat exchanger network of HAT consists of intercooler(if there is),aftercooler,recuperator,economizer and humidifier,which brings higher efficiency but makes the system more *** simplify HAT layout,a novel humidifier concept is proposed by integrating the aftercooler into traditional counter-current *** on this concept,a one-dimensional model including pressure drop and exergy calculation is established to distinguish the thermodynamic and hydrodynamic characteristics,and then the structural parameters,such as the number of rows and columns,tube diameter,pitch and type for a micro HAT are *** results show that the aftercool-humidifier plays the same role as original aftercooler and humidifier,and can match the in-tube air,out-tube air and water stream well with lower *** the case of micro HAT cycle,the volume of heat and mass transfer area can be reduced by 47%compared with traditional *** major thermal resistance occurred in the convection heat transfer process inside the tube;however,using enhanced tube cannot effectively improve the compactness of device.

关键词： humid air turbine cycle humidifier thermodynamic analysis one-dimensional model

Designing a Phthalonitrile/Benzoxazine Blend for the Advanced GFRP Composite Materials

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Chinese Journal of Polymer Science 2018年第1期36卷 106-112页

作者： xu-Lin Yang Kui Li ming-zhen xu Xiao-Bo Liu Research Branch of Functional Materials Institute of Microelectronic & Solid State Electronic University of Electronic Science and Technology of China

High performance resin must be used in the high performance glass fiber-reinforced plastic（GFRP） composites, but it is sometimes difficult to balance the processabilities and the final properties in the design of advanced thermoset GFRP composites. In this study, a phthalonitrile/benzoxazine（PPN/BZ） blend with excellent processability has been designed and applied in the GFRP composite materials. PPN/BZ blend with good solubility, low melt viscosity, appropriate gel condition and low-temperature curing behavior could enable their GFRP composite preparation with the prepreg-laminate method under a relatively mild condition. The resulted PPN/BZ GFRP composites exhibit excellent mechanical properties with flexural strength over 700 MPa and flexural modulus more than 19 GPa. Fracture surface morphologies of the PPN/BZ GFRP composites show that the interfacial adhesion between resin and GF is improved. The temperatures at weight loss 5%（T_（5%）） and char residue at 800 °C of all PPN/BZ GFRP composites are over 435 °C and 65% respectively. PPN/BZ GFRP composites with high performance characteristics may find applications under some critical circumstances with requirements of high mechanical properties and high service temperatures.

关键词： Phthalonitrile Benzoxazine High performance composite GFRP composites

High-Performance Recyclable Furan-based Epoxy Resin and Its Carbon Fiber Composites with Dense Hydrogen Bonding

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Chinese Journal of Polymer Science 2024年第1期42卷 73-86,I0008页

作者： Chang-Bo Zhao Lu-Kun Feng Hui Xie ming-Liang Wang Bing Guo Zhi-Yong xue Cai-zhen Zhu Jian xu Advanced Materials Research Institute North China Electric Power UniversityBejing 102206China Institute of Low-Dimensional Materials Genome Initiative College of Chemistry and Environmental EngineeringShenzhen UniversityShenzhen 518060China Chengdu Institute of Organic Chemistry Chinese Academy of SciencesChengdu 610041China School of Science and Shenzhen Key Laboratory of Flexible Printed Electronics Technology and Shenzhen Key Laboratory of Advanced Functional Carbon Materials Research and Comprehensive ApplicationHarbin Institute of TechnologyShenzhen 518055China

The emerging biomass-based epoxy vitrimers hold great potential to fulfill the requirements for sustainable development of *** the existence of dynamic chemical bonds in vitrimers often reduces both the thermal and mechanical properties of epoxy resins, it is challenging to produce recyclable epoxy vitrimers with both excellent mechanical properties and good thermal stability. Herein, a monomer 4-(((5-(hydroxymethyl)furan-2-yl)methylene)amino)phenol(FCN) containing furan ring with potential to form high density of hydrogen bonding among repeating units is designed and copolymerized with glycerol triglycidyl ether to yield epoxy resin(FCN-GTE), which intrinsically has dual hydrogen bond networks, dynamic imine structure and resultant high performance. Importantly, as compared to the BPA-GTE, the FCN-GTE exhibits significantly improved mechanical properties owing to the increased density of hydrogen bond network and physical crosslinking interaction. Furthermore, density functional theory(DFT) calculation and in situ FTIR analysis is conducted to decipher the formation mechanism of hydrogen bond network. In addition, the FCN-GTE possesses superior UV shielding, chemical degradation, and recyclability because of the existence of abundant imine bonds. Notably, the FCN-GTE-based carbon fiber composites could be completely recycled in an amine *** study provides a facile strategy for synthesizing recyclable biomass-based high-performance epoxy vitrimers and carbon fiber composites.

关键词： Furan Hydrogen bond network Dynamic Schiff base Carbon fiber composites Recycling

Astrometric Observations of NEA 1998 HH49 Using the Daocheng 50 cm Telescope

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Research in Astronomy and Astrophysics 2024年第7期24卷 74-81页

作者： Huan xu Xiang-ming Cheng Yi-Gong Zhang Teng-Fei Song zhen-Jun Zhang Qing-Yu Peng Yunnan Observatories Chinese Academy of Sciences University of Chinese Academy of Sciences Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Engineering Laboratory on Applied Astronomical Technology of Yunnan School of Information Engineering Kunming University School of Computer Science and Information Engineering Anyang Institute of Technology Department of Computer Science Jinan University Sino-French Joint Laboratory for Astrometry Dynamics and Space ScienceJinan University

This study details an astrometric observation campaign of the Near-Earth Asteroid 1998 HH49, conducted with the aim of refining our understanding of its physical characteristics. Utilizing the 50 cm telescope located at the Wumingshan Mountain in Daocheng, Sichuan, images were obtained over four nights, from 2023 October 19 to October 22. These observations were processed using Astrometrica software, facilitating the precise determination of the asteroid's position. The observational results were compared with the ephemerides from three distinct sources to verify accuracy: the Jet Propulsion Laboratory(JPL) Horizons System, the Institut de Mécanique Céleste et de Calcul des éphémérides(IMCCE) Miriade, and the Near-Earth Objects Dynamic Site(NEODyS-2).When compared with the JPL ephemeris, a mean observed-minus-calculated(O-C) result of 0.''07 in the *** and-0.''35 in the decl. direction was yielded. Furthermore, the comparison with the IMCCE ephemeris yielded mean O-C results of 0.''08 in the R.A. direction and-0.''06 in the decl. direction. The comparison with the NEODyS-2 ephemeris yielded the mean O-C results of 0.''06 in R.A. and-0.''49 in decl. direction. The study's findings demonstrate a general consistency between the observed data and the ephemeris predictions, with minor discrepancies observed across the data sets. Notably, both the JPL and NEODyS-2 ephemerides show that the residuals in the decl. direction exceed those in the R.A. direction. The disparities may result from atmospheric differential color refraction, ephemeris discrepancies, observational errors, and other factors. Additionally, it is worth noting that further investigation is required due to the potential influence of additional factors. Overall, the Daocheng 50 cm Telescope exhibits the ability to conduct high-precision positional measurements.

关键词： astrometry ephemerides time

Analytic phase structures and thermodynamic curvature for the charged AdS black hole in alternative phase space

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Frontiers of physics 2021年第2期16卷 209-215页

作者：许震明 Institute of Modem Physics Northwest UniversityXi'an 710127China School of Physics Northwest UniversityXi'an 710127China Shaanxi Key Laboratory for Theoretical Physics Frontiers Xi’an 710127China Peng Huanwu Center for Fundamental Theory Xi’an 710127China

In this paper,we visit the thermodynamic criticality and thermodynamic curvature of the charged AdS black hole in a new phase *** is shown that when the square of the total charge of the charged black hole is considered as a thermodynamic quantity,the charged AdS black hole also admits a van der Waals-type critical behavior without the help of thermodynamic pressure and thermodynamic *** on this,we study the fine phase structures of the charged AdS black hole with fixed AdS background in the new *** the one hand,we give the phase diagram structures of the charged AdS black hole accurately and analytically,which fills up the gap in dealing with the phase transition of the charged AdS black holes by taking the square of the charge as a thermodynamic *** the other hand,we analyse the thermodynamic curvature of the black hole in two coordinate *** thermodynamic curvatures obtained in two different coordinate spaces are equivalent to each other and are also *** on an empirical conclusion under the framework of thermodynamic geometry,we speculate that when the square of charge is treated as an independent thermodynamic quantity,the charged AdS black hole is likely to present a repulsive between its *** importantly,based on the thermodynamic curvature,we obtain a universal exponent at the critical point of phase transition.

关键词： thermodynamics of black hole phase transition the Maxwell construction the Ruppeiner

Collaborative Charging Scheduling in Wireless Charging Sensor Networks

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Computers, Materials & Continua 2024年第4期79卷 1613-1630页

作者： Qiuyang Wang zhen xu Lei Yang School of Electrical and Electronic Engineering Wuhan Polytechnic UniversityWuhan430048China

Wireless sensor networks (WSNs) have the trouble of limited battery power, and wireless charging provides apromising solution to this problem, which is not easily affected by the external environment. In this paper, we studythe recharging of sensors in wireless rechargeable sensor networks (WRSNs) by scheduling two mobile chargers(MCs) to collaboratively charge sensors. We first formulate a novel sensor charging scheduling problem with theobjective of maximizing the number of surviving sensors, and further propose a collaborative charging schedulingalgorithm(CCSA) for WRSNs. In the scheme, the sensors are divided into important sensors and ordinary *** can adaptively collaboratively charge the sensors based on the energy limit ofMCs and the energy demandof sensors. Finally, we conducted comparative simulations. The simulation results show that the proposed algorithmcan effectively reduce the death rate of the sensor. The proposed algorithm provides a solution to the uncertaintyof node charging tasks and the collaborative challenges posed by multiple MCs in practical scenarios.

关键词： Wireless rechargeable sensor network mobile charger collaborative charging adaptive charging

Clinical experience sharing on gastric microneuroendocrine tumors: A case report

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World Journal of Clinical Cases 2024年第4期12卷 795-800页

作者： You-Jun Wang Da-ming Fan Yu-Shuang xu Qi Zhao zhen-Fang Li Department of Gastroenterology Central Hospital Affiliated to Shandong First Medical UniversityJinan 250000Shandong ProvinceChina Department of Pathology Central Hospital Affiliated to Shandong First Medical UniversityJinan 250000Shandong ProvinceChina Department of Gastroenterology The Affiliated Hospital of Qingdao UniversityQingdao 266000Shandong ProvinceChina

BACKGROUND The majority of gastric neuroendocrine tumors(G-NENs)are present in various lesions under endoscopy,and they can be polypoid uplifts,submucosal tumors or papules,erosions,and *** lesions are mostly confined to the mucosal or submucosal layer,usually less than 2 cm,and exclusively localized to the gastric body or *** type 1 G-NENs,about 22%of cases have no visible lesions under an endoscope,and such lesions can only be detected via biopsies(microcar-cinoids).CONCLUSION In the case under study,the patient did not have any visible raised lesions under a gastroscope,and the lesions were found only after a random *** article combines the endoscopic manifestations and clinical features of the lesions in this case to improve the diagnosis of G-NENs.

关键词： Neuroendocrine tumor Micro carcinoids Endoscopy Case report