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Science China Technological Sciences 2024年

作者： TANG ShuWei WANG Hao WAN Da LI XiaoDong GUO WanRong ZHENG Tuo QI XiuLing BAI ShuLin College of Materials Science and Engineering Liaoning Technical University Faculty of Chemistry Northeast Normal University

The crystal structure,mechanical stability,phonon dispersion,electronic transport properties and thermoelectric （TE） performance of the Bi2Sn2Te6monolayer are assessed with the first-principles calculations and the Boltzmann transport *** Bi2Sn2Te6monolayer is an indirect semiconductor with a band gap of 0.91 eV using the Heyd-Scuseria-Ernzerhof （HSE06）functional in consideration of the spin-orbit coupling （SOC） *** Bi2Sn2Te6monolayer is high thermodynamically and mechanically stable by the assessments of elastic modulus,phonon dispersion curves,and ab initio molecular dynamics （AIMD）*** hybrid bonding characteristics are discovered in Bi2Sn2Te6monolayer,which is advantageous for phonon *** antibonding interactions near the Fermi level weaken the chemical bonding and reduce the phonon vibrational *** to the short phonon relaxation time,strong anharmonic scattering,large Grüneisen parameter,and small phonon group velocity,an ultralow lattice thermal conductivity (0.27 W/（m·K）@300K) is achieved for the *** optimal dimensionless figure of merit （ZT） values for the n-type and p-type Bi2Sn2Te6monolayers are 2.68 and 1.63 at 700 K,respectively,associated with a high TE conversion efficiency of 20.01%at the same ***,the Bi2Sn2Te6monolayer emerges as a promising candidate for TE material with high conversion efficiency.

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Difference in microstructural characteristics of stamp-charged coke and gravity-charged coke with approximate macroscopic performance

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Journal of Iron and Steel Research International 2024年第5期31卷 1050-1062页

作者： Chong Zou Zheng-yan Huang Jian-yun Li Bin Li Shi-wei Liu Yuan She School of Metallurgical Engineering Xi’an University of Architecture and TechnologyXi’an710311ShaanxiChina technical Center of Shandong Iron and Steel Co. Ltd.(Laiwu Branch)Jinan271104ShandongChina

The microstructural characteristics including optical texture,porosity and pore structure and chemical structure of stamp-charged coke(SCC)and gravity-charged coke(GCC)with similar conventional macro-indicators were investigated,and the properties including micro-strength,reactivity of coke matrix and that after alkali enrichment were comparatively studied by various characterization *** anisotropic structure of SCC is composed of high content of fine mosaic texture,while the content of medium mosaic texture,coarse texture and fibrous texture is *** statistical average shows that the fine mosaic average of SCC(24.89%)is 3.78 times the GCC average(6.58%),and the coarse mosaic average(1.24%)is only about 1/3 of the GCC average(3.43%).The porosity of SCC is lower than that of GCC,but tamping process does not lead to the fact that the number of closed pores of SCC is significantly lower than that of *** the structure of SCC is compact,its pore number is large and the pore wall is *** of coke with diameter less than 150 nm seem unaffected by tamping *** aromatic structure of SCC was less ordered than that of GCC,which was speculated to be related to the addition of more low metamorphic coal in *** microscopic strength and structural strength of SCC are lower than those of *** reactivity of coke matrix is affected by the specific surface area,but it is not the determining factor of its *** improvement in dissolution reactivity of coke after potassium enrichment is independent of coke type.

关键词： Stamp-charged coke Optical texture Porosity Microstructure Reactivity

Synergistic extraction of rare earth elements and alumina from coal fly ash by potassium pyrosulfate

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Journal of Rare Earths 2024年第4期42卷 749-758页

作者： Jingjing Zou Yiping Sun Chunbin Guo Daye Chen Yonghong Song Yongfeng Wu Zhaotianhui Li Department of Environment Science and Engineering Liaoning Technical UniversityFuxin23000China Department of Materials Science and Engineering Liaoning Technical UniversityFuxin123000 China Technology Research and Development Department Chinese Institute of Coal ScienceBeijing100013China Shenhua Zhungeer Energy and Resource Comprehensive Development Co. Ltd.Erdos10300China Liaoning Yingguan High-tech Ceramic Co. Ltd.Jinzhou121213China

Although coal fly ash(CFA)contains a high content of rare earth elements(REEs),the related extraction methods have limitations because of their low efficiencies,high levels of energy consumption,and other *** address these problems,in this study,we examined the coextraction of REEs and Al_(2)O_(3)from two types of Al_(2)O_(3)-rich CFA,pulverized CFA(PCFA)and circulating fluidized bed fly ash(CFBFA)using low-temperature calcination in the presence of K_(2)S_(2)O_(7).The total REEs,heavy REEs(HREEs),and light REEs(LREEs)extraction efficiencies were determined using different K_(2)S_(2)O_(7)/Al_(2)O_(3) molar ratios and calcination temperatures and correlated with the Al_(2)O_(3) extraction efficiency using Pearson correlation coefficient *** REEs are concentrated within CFA particles encapsulated in an aluminosilicate glass phase,and the REEs extraction efficiency is related to the form of Al in *** extraction efficiencies of Al_(2)O_(3) and REEs increase as the K_(2)S_(2)O_(7)/Al_(2)O_(3) molar ratio and calcination temperature increase,and the extraction selectivity of the more industrially valuable HREEs from CFBFA is *** high K_(2)S_(2)O_(7)/Al_(2)O_(3) molar ratios,the extraction of REEs from PCFA is more efficient than that from CFBFA with the regeneration of the highly active Al-O-Si bonds in *** Al_(2)O_(3) extraction efficiencies of PCFA as well as CFBFA correlate strongly with the total REEs,HREEs,and LREEs extraction *** developed extraction technology has the potential to promote CFA valorization and expand REEs resources,thus mitigating the bottlenecks of REEs procurement.

关键词： Rare earths Alumina Coal fly ash Potassium pyrosulfate Calcination Extraction

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Thermoelectric performance of Bi2Sn2Te6 monolayer with ultralow lattice thermal conductivity induced by hybrid bonding properties: A theoretical prediction

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Science China Technological Sciences 2024年第11期67卷 3381-3393页

The crystal structure,mechanical stability,phonon dispersion,electronic transport properties and thermoelectric（TE） performance of the Bi2Sn2Te6monolayer are assessed with the first-principles calculations and the Boltzmann transport *** Bi2Sn2Te6monolayer is an indirect semiconductor with a band gap of 0.91 eV using the Heyd-Scuseria-Ernzerhof（HSE06） functional in consideration of the spin-orbit coupling（SOC） *** Bi2Sn2Te6monolayer is high thermodynamically and mechanically stable by the assessments of elastic modulus,phonon dispersion curves,and ab initio molecular dynamics（AIMD） *** hybrid bonding characteristics are discovered in Bi2Sn2Te6monolayer,which is advantageous for phonon *** antibonding interactions near the Fermi level weaken the chemical bonding and reduce the phonon vibrational *** to the short phonon relaxation time,strong anharmonic scattering,large Grüneisen parameter,and small phonon group velocity,an ultralow lattice thermal conductivity(0.27 W/（m·K）@300 K) is achieved for the *** optimal dimensionless figure of merit（ZT） values for the n-type and p-type Bi2Sn2Te6monolayers are 2.68 and 1.63 at 700 K,respectively,associated with a high TE conversion efficiency of 20.01% at the same ***,the Bi2Sn2Te6monolayer emerges as a promising candidate for TE material with high conversion efficiency.

关键词： A2B2Te6 family hybrid bonding antibonding interactions ultralow lattice thermal conductivity first-principles calculations

Expedition to the blockchain application potential for higher education institutions

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Blockchain(Research and Applications) 2024年第3期5卷 53-66页

作者： Matthias Gottlieb Christina Deutsch Felix Hoops Hans Pongratz Helmut Krcmar Bavarian Ministry of Digital Affairs 80333 MunichGermany technical University of Munich 85478 Garching By MunichGermany TU Dortmund University 44139 DortmundGermany

In the education sector,blockchain is currently at the end of the peak of inflated expectations in Gartner’s Hype ***,it is crucial to understand whether this technology meets the expectations of Higher education Institutions(HEIs).We go on an expedition to identify blockchain application scenarios and its potential for HEI administration-the universities are digitalized to just 23.3%.Current information systems research addresses classifications of blockchain-based projects(application level)rather than their technical realization(protocol level).Thus,when evaluating blockchain application scenarios in HEI administration,we intensively consider the technical side of blockchain-based *** perform a threestep approach:(1)systematic literature review,(2)qualitative exploratory semi-structured interviews to sup-plement information on market-ready solutions,and(3)an evaluation of the potential of the blockchain-based projects identified,based on HEI administration *** find that the leading blockchain application scenarios are credential verification and *** the protocol level,we obtain equivocal results regarding the technical realization of projects,e.g.,their underlying blockchain types and storage *** the application level,when discussing the potential of different projects,we find that most of them address adaptability,complexity decomposition,and cost reduction requirements between HEIs;interest diversity and stakeholder collaboration between HEIs and business actors;privacy and trust between HEIs and students.

关键词： Blockchain Higher education institution(HEI) Administration Protocol level Application level Application

Study of relationship between motion of mechanisms in gas operated weapon and its shock absorber

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Defence Technology（防务技术） 2024年第3期33卷 42-54页

作者： Jiri Balla Roman Vitek Dung Nguyen Van Zbynek Krist Hung Nguyen Van Department of Weapons and Ammunition University of Defence BrnoCzech Republic Department of Weapons Le Quy Don Technical UniversityHanoiViet Nam Department of Design and Special Engineering Alexander Dubcek University of TrencinSlovakia

The article deals with the motion of the breech block carrier and the weapon casing of an automatic weapon mounted on a flexible carriage and the base of the *** works,which did not consider the dynamic properties of the base of the weapon,did not allow to reconcile the calculated and experimental results of the weapon casing displacement when shooting from firing *** the analysis of the motion of individual parts,the methods of mathematical modelling and firing experiments using a high-speed camera were *** show the best accord with experiment when modelling the system with 4 degrees of *** oscillation of the system regarding the movement of the breech block carrier and the weapon casing was investigated under changed conditions of rate of fire,the use of a muzzle brake and different types of shock *** velocities and displacements of the weapon casing and the breech block carrier at different values of the impulse of the gases to the breech block carrier were determined.

关键词： Shock absorber Gas-operated weapon Force-impulse diagram Recoil system Breech block carrier

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Impact of Dewatering on the Spatio-Temporal Distribution of Benthic Macroinvertebrate Communities in the Okpara River, Benin

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Journal of Geoscience and Environment Protection 2024年第2期12卷 30-43页

作者： Sylvain Tayéwo Biaou Fadéby Modeste Gouissi Armelle Sabine Yélignan Hounkpatin Zoulkanerou Orou Piami Wakili Bolatito Yessoufou Souradjou Orou Goura Nonvignon Martial Fassinou Laboratory of Ecology Health and Animal Production (LESPA) Faculty of Agronomy (FA) University of Parakou (UP) Parakou Benin Pluridisciplanary Research Laboratory for technical education (LARPET) University of Sciences Technologies Engineering and Mathematics of Abomey (UNSTIM) Lokossa Benin

Surface watercourses are areas of very high ecological and heritage value. Macroinvertebrates are bioindicators of the health of aquatic ecosystems. The aim of this study was to assess the effects of dewatering and re-watering cycles on benthic macroinvertebrate (BMI) communities. Two data collections were carried out at two stations (Okpara 1 and Okpara 2) on the Okpara river before and after dewatering. Thus, 8 samples of benthic macroinvertebrates and 12 physico-chemical parameters (T°C, pH, Transparency, Depth, Conductivity, Dissolved Oxygen that were measured in situ, and BOD5, COD, NH4+, NO3-, NO2- and PO43-) were assayed in the laboratory. Canonical Correspondence Analysis (CCA) was used to match physico-chemical data to MIB families. Shannon and Piélou diversity indices were used to determine the effects of dewatering on MIBs. The increase in temperature values of pH, BOD5, COD, NH4+, NO3-, NO2- and PO43-, after re-watering indicates the effect of dewatering on the quality of Okpara aquatic ecosystems. The benthic macrofauna collected consisted of 62.42% insects, 0.65% crustaceans, 6.48% molluscs, 0.72% worms and 0.14% arachnids. Whereas after re-watering, 21.67% insects, 0% crustaceans, 0.22% molluscs, 7.56% worms and 0.29% arachnids were recorded. Insects, crustaceans and molluscs were more abundant before dewatering than after. This was revealed by low abundances and taxonomic richness, as well as low Shannon index values of samples collected after re-watering.

关键词： Dewatering Benthic Macroinvertebrates Impact Physico-Chemical Parameters Okpara Rivers Nord-Benin

Electrical Installation Safety Assessment of Buildings in Kumasi, Ghana

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Journal of Power and Energy Engineering 2024年第9期12卷 84-101页

作者： Bismark Mante Francois Sekyere Prince Asabere Isaac Prempeh Willie K. Ofosu Department of Electrical and Electronic education AAMUSTED Kumasi Ghana Department of Electrical and Electronic Engineering Ho Technical University Ho Ghana School of Engineering Design Technology and Professional Programs Penn State Wilkes-Barre Lehman PA USA

This study aims to evaluate the safety status of electrical installations in residential and commercial buildings within the Suame ECG strategic business unit, Ghana, focusing on compliance with international and Ghanaian wiring standards. The research assesses key factors influencing safety, including the certification of electricians, the quality of cable brands used, proper cable sizing, adherence to wiring color codes, the awareness and use of Residual Current Circuit Breakers (RCCBs), and the protection of earth electrodes. A descriptive research design was utilized, involving extensive field surveys and electrical installation audits. Data were collected using standardized tools and analyzed with SPSS software to evaluate the professional competencies of artisans and their adherence to safety standards. The findings indicate significant safety risks, with 69.7% of electricians lacking proper certification, leading to the widespread use of non-approved cable brands, improper cable sizing, and deviations from wiring color codes. Additionally, deficiencies were found in the awareness and use of RCCBs and the protection of earth electrodes. The study concludes with recommendations to enhance electrical safety, including mandatory certification for electricians, public awareness campaigns, regular inspections, and ongoing training and development programs. These measures are crucial for improving the overall safety and quality of electrical installations in the Suame area, Ghana.

关键词： Earthing System Energy Commission Ghana Wiring Code Residual Current Circuit Breaker Safety

Mechanical response of a tunnel subjected to strike-slip faulting processes,based on a multi-scale modeling method

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Frontiers of Structural and Civil Engineering 2024年第8期18卷 1281-1295页

作者： Guoguo LIU Ping GENG Tianqiang WANG Xiangyu GUO Jiaxiang WANG Ti DING Key Laboratory of Transportation Tunnel Engineering Ministry of EducationChengdu 610031China College of Civil Engineering Huaqiao UniversityXiamen 361021China China Railway Design Corporation Tianjin 300308China

The stick-slip action of strike-slip faults poses a significant threat to the safety and stability of underground *** this study,the north-east area of the Longmenshan fault,Sichuan,provides the geological background;the rheological characteristics of the crustal lithosphere and the nonlinear interactions between plates are described by Burger’s viscoelastic constitutive model and the friction constitutive model,respectively.A large-scale global numerical model for plate squeezing analysis is established,and the seemingly periodic stick-slip action of faults at different crust depths is *** a second model at a smaller scale,a local finite element model(sub-model),the time history of displacement at a ground level location on the Longmenshan fault plane in a stick-slip action is considered as the displacement *** integration of these models,creating a multi-scale modeling method,is used to evaluate the crack propagation and mechanical response of a tunnel subjected to strike-slip *** determinations of the recurrence interval of stick-slip action and the cracking characteristics of the tunnel are in substantial agreement with the previous field investigation and experimental results,validating the multi-scale modeling *** can be concluded that,regardless of stratum stiffness,initial cracks first occur at the inverted arch of the tunnel in the footwall,on the squeezed side under strike-slip *** smaller the stratum stiffness is,the smaller the included angle between the crack expansion and longitudinal direction of the tunnel,and the more extensive the crack expansion *** the tunnel in a high stiffness stratum,both shear and bending failures occur on the lining under strike-slip faulting,while for that in the low stiffness stratum,only bending failure occurs on the lining.

关键词： stick-slip action plate squeezing analysis multi-scale modeling method lining cracking mechanical response

Study on surface discharge of nonlinear conductive epoxy resin/SrTiO3 composites in 80–300 K temperature zone

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High Voltage 2024年第1期9卷 117-126页

作者： Yunqi Xing Bin Wang Mingyang Wang Jiakai Chi Peng Jia Rongjin Huang State Key Laboratory of Reliability and Intelligence of Electrical Equipment Hebei University of TechnologyTianjinChina Key Laboratory of Electormagnetic Field and Electrical Apparatus Reliability of Hebei Province Hebei University of TechnologyTianjinChina Key Laboratory of Special Machine and High Voltage Apparatus(Ministry of education) Shenyang University of TechnologyShenyangChina State Grid Tianjin High Voltage Company TianjinChina China Energy Engineering Group Tianjin Electric Power Design Institute Co. Ltd.TianjinChina CAS Key Laboratory of Cryogenics Technical Institute of Physics and ChemistryBeijingChina

Bisphenol F epoxy resin(EP)is often used in terminal current lead insulation of superconducting equipment because of its good insulation performance,high mechanical strength,good toughness at cryogenic temperatures,and resistance to cold shock and heat ***,due to the wide temperature range of 80–300 K and the strong electric field,the EP-N_(2)interface is prone to surface flashover,resulting in terminal insulation *** improve the reliability of the current lead insulation,non-linear conductive EP/strontium titanate(SrTiO_(3))composites were prepared by modification with nano *** changes of dielectric,surface discharge,flashover,and trap distribution characteristics of composite materials were studied,and the mechanism of SrTiO_(3)on the surface flashover of composite materials was *** results show that the conductivity of the composite increases with the rise of SrTiO_(3)filling content,and the amplitude of improvement is greater under the strong electric field,showing a more significant *** composite has a lower trap energy level and a greater number of shallow traps compared to pure EP,which accelerates surface charge detrapping and reduces charge accumulation,effectively enhancing the discharge and surface flashover voltage of the composite.

关键词： composites composite insulation