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Gravitational waves and primordial black hole productions from gluodynamics by holography

Science China(Physics,Mechanics & Astronomy) 2024年第4期67卷 31-42页

作者： Song He li li Zhibin li Shao-Jiang wang Center for Theoretical Physics and College of Physics Jilin UniversityChangchun 130012China Max Planck Institute for Gravitational Physics(Albert Einstein Institute) Golm 14476Germany CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of SciencesHangzhou 310024China Peng Huanwu Collaborative Center for Research and Education Beihang UniversityBeijing 100191China School of Physics and Microelectronics Zhengzhou UniversityZhengzhou 450001China

Understanding the nature of quantum chromodynamics(QCD)matter is important but challenging due to the presence of nonperturbative dynamics under extreme *** construct a holographic model describing the gluon sector of QCD at finite temperatures in the non-perturbative *** equation of state as a function of temperature is in good accordance with the lattice QCD ***,the Polyakov loop and the gluon condensation,which are proper order parameters to capture the deconfinement phase transition,also agree quantitatively well with the lattice QCD *** obtain a strong first-order confinement/deconfinement phase transition at Tc=276.5 Me V that is consistent with the lattice QCD *** on our model for a pure gluon hidden sector,we compute the stochastic gravitational waves and primordial black hole(PBH)productions from this confinement/deconfinement phase transition in the early *** resulting stochastic gravitational-wave backgrounds are found to be within detectability in the International Pulsar Timing Array and Square Kilometre Array in the near future when the associated productions of PBHs saturate the current observational bounds on the PBH abundances from the liGO-Virgo-Collaboration O3 data.

关键词： AdS/QCD confinement/deconfinement phase transition gravitational wave primordial black hole

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Comparison of thermal shock resistance capabilities of the rotary swaged pure tungsten,potassium-doped tungsten,and W-La2O3 alloys

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Tungsten 2024年第4期6卷 759-766页

作者： Tao Yang Hao wang Fan Feng Xiang liu Xue-Yu Gong You-Yun lian Jian-Bao wang School of Nuclear Science and Technology University of South China Southwestern Institute of Physics

Tungsten-based materials are one of the most important candidates for the plasma facing materials（PFMs） of future fusion reactors,and it is necessary to study the properties of tungsten-based materials under the service conditions of fusion devices to ensure the long-term steady-state operation of future fusion *** this paper,different tungsten-based materials made by the same rotary swaging process are selected to simulate the transient thermal loads on the PFMs of a fusion reactor using an electron beam,and thermal load experiments are carried out by changing the power density of a loading pulse and the pulse *** is found that different tungsten-based materials made by the same process have large differences in thermal shock resistance,and the doped tungsten materials（W-K and W-La2O3） are significantly better than the pure tungsten materials with the increase in thermal shock power density and the number of cycles,especially the W-K materials,which have excellent performance.

关键词： Electron beam Rotary swaging Thermal shock Tungsten materials

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Hydrographic Characteristics and Oceanic Heat Flux in the Upper Arctic Ocean over the Alpha Ridge Observed by the DTOP Platform in 2018 and 2021

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Journal of Ocean University of China 2024年第2期23卷 304-316页

作者： wang Yongjun li Tao College of Oceanic and Atmospheric Sciences Ocean University of ChinaQingdao 266100China Frontier Science Center for Deep Ocean Multispheres and Earth System(FDOMES) and Physical Oceanography Laboratory Ocean University of ChinaQingdao 266100China Laoshan Laboratory Qingdao 266237China

In 2018 and 2021,the Drift-Towing Ocean Profilers(DTOP)provided extensive temperature and salinity data on the upper 120m ocean through their drifts over the Alpha Ridge north of the Canada *** thickness and temperature maximum of Alaska Coastal Water(ACW)ranged from 20m to 40m and-1.5℃to-0.8℃,respectively,and the salinity generally maintained from 30.2 to *** with World Ocean Atlas 2018’s climatology manifested a 40m-thick and warm ACW roughly ex-ceeding the temperature maximum by 0.4–0.5℃in June–August *** anomalously warm ACW was highly related to the ex-pansion of the Beaufort Gyre in the negative Arctic Oscillation *** summer,the under-ice oceanic heat flux F_(w)^(OHF)was elevated,with a maximum value of above 25Wm^(-2).F_(w)^(OHF)was typically low in the freezing season,with an average value of 1.2Wm^(-2).The estimates of upward heat flux contributed by ACW to the sea ice bottom F_(w)^(OHF)were in the range of 3–4Wm^(-2)in June–August 2021,when ACW contained a heat content of more than 80MJm^(-2).The heat loss over this period was driven by a weak stratification upon the ACW layer associated with a surface mixed layer(SML)approaching the ACW *** autumn,F_(w)^(OHF)was reduced(ling north of the Canada Basin,was largely responsible for the substantial cooling and thinning of the ACW layer in the summer of 2021.

关键词： Arctic Ocean oceanic heat flux Alaska Coastal Water Alpha Ridge

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Adaptive Barrier-Lyapunov-Functions Based Control Scheme of Nonlinear Pure-Feedback Systems with Full State Constraints and Asymptotic Tracking Performance

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Journal of Systems Science & Complexity 2024年第3期37卷 965-984页

作者： NIU Ben wang Xiaoan wang Xiaomei wang Xinjun li Tao Faculty of Electronic Information and Electrical Engineering Dalian University of TechnologyDalian 116024China School of Information Science and Engineering Shandong Normal UniversityJinan 250014China School of Mathematics Southeast UniversityNanjing 211189China School of Automation Nanjing University of Information Science and TechnologyNanjing 210044China

In this paper,the authors propose an adaptive Barrier-Lyapunov-Functions(BLFs)based control scheme for nonlinear pure-feedback systems with full state *** to the coexist of the non-affine structure and full state constraints,it is very difficult to construct a desired controller for the considered *** to the mean value theorem,the authors transform the pure-feedback system into a system with strict-feedback structure,so that the well-known backstepping method can be ***,in the backstepping design process,the BLFs are employed to avoid the violation of the state constraints,and neural networks(NNs)are directly used to online approximate the unknown packaged nonlinear *** presented controller ensures that all the signals in the closed-loop system are bounded and the tracking error asymptotically converges to ***,it is shown that the constraint requirement on the system will not be violated during the ***,two simulation examples are provided to show the effectiveness of the proposed control scheme.

关键词： Asymptotic tracking control barrier Lyapunov functions full state constraints nonlinear pure-feedback systems

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The adsorption effect of aquaculture residual feed on heavy metals and its impact on microbial metabolism of feed

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Ecological Processes 2024年第2期13卷 246-259页

作者： Sufeng wang Zijng wang Wen Zhang Jingshan li Mingyang lin li Chen State Key Laboratory of Metastable Materials Science and Technology Hebei Key Laboratory of Heavy Metal Deep-Remediation in Water and Resource Reuse Yanshan University Key Laboratory of Pollution Exposure and Health Intervention of Zhejiang Province College of Biology and Environmental EngineeringZhejiang Shuren University Hebei Ocean & Fisheries Science Research Institute

Background Intensive and large-scale aquaculture has a high biological density, and a large amount of artificial feed must be provided. As a result, residual feed would be discharged into natural water bodies with water exchange. Due to heavy metal pollution in surface water, residual feed may adsorb heavy metals in the water, affecting the subsequent microbial degradation of feed and the restoration of the water environment. The combined ecological impacts of these two types of pollution urgently need to be *** This study explored the adsorption effect of residual feed on heavy metals and its impact on microbial degradation of residual feed. The results showed that both the insoluble component（mainly fiber, ash, and ether extract, abbreviated as FAE） and soluble component（soluble protein and starch） of the feed had adsorption effects on heavy metals. As the salinity increased, the adsorption capacity of Cu2+and Cd2+decreased, while the adsorption effect on Pb2+was not changed significantly. The adsorption of heavy metals by residual feed could affect the biological degradation of residual feed. The residual feed could adsorb heavy metals and bacterial cells simultaneously, forming FAE-B（bacteria）-S（starch）-Pr（protein）-metal adsorption complex. This adsorption effect could reduce the negative impact of heavy metals on microbial degradation of residual feed. The simulated degradation experiments in actual water bodies also confirmed this. However, the accumulation of heavy metals in residual feed may bring negative effects, such as being consumed by aquatic organisms and entering the food *** The results of this study provide a basis for the collection and centralized treatment of residual feed in aquaculture, as well as the control and remediation of residual feed pollution in natural water bodies.

关键词： Residual feed Adsorption complex Feed pollution Heavy metal

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Shape and composition evolution of Pt and Pt_(3)M nanocrystals under HCl chemical etching

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Chinese Chemical Letters 2024年第9期35卷 403-407页

作者： lian Sun Honglei wang Ming Ma Tingting Cao Leilei Zhang Xingui Zhou State Key Laboratory of NBC Protection for Civilian Beijing 102205China Science and Technology on Advanced Ceramic Fibers and Composites Laboratory College of Aerospace Science and EngineeringNational University of Defense TechnologyChangsha 410073China School of Materials Science and Engineering Beijing Institute of TechnologyBeijing 100081China State Key Laboratory of Crystal Materials and Institute of Crystal Materials Shandong UniversityJi’nan 250100China

Controlling the shape and composition of Pt-based nanocrystals is essential to improve electrocatalytic *** this work,we have carefully investigated the evolution process of morphology and composition for Pt and Pt_(3)M(M=Ni,Co)nanocrystals by hydrochloric acid(HCl)*** a result,only Pt_(3)Ni nanocrystals successfully formed unsaturated step-like atoms on the surface and then constructed high-index facets(HIFs),while Pt and Pt_(3)Co preserved a good octahedron *** functional theory(DFT)calculation suggests that Cl-ions can be tightly adsorbed on the surface of Pt_(3)Ni rather than other nanocrystals,which hinders the deposition of newly-reduced atoms and thus regulating the surface ***,the etching of surface transitional metals further accelerates the formation of *** by the active sites on the surface,HCl-Pt-Ni exhibited a~10.8 and~11.3 times higher oxygen reduction reaction(ORR)mass and specific activities than commercial Pt/C catalyst,and possessed a good durability after 10,000 cycles *** work gives a deep insight into the design of high-performance Pt-based ORR catalysts.

关键词： Electrocatalysts Nanocrystals Platinum Oxygen reduction reaction DFT calculation

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Engineering oxygen vacancies on Tb-doped ceria supported Pt catalyst for hydrogen production through steam reforming of long-chain hydrocarbon fuels

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Chinese Journal of Chemical Engineering 2024年第4期68卷 181-192页

作者： Zhourong Xiao Changxuan Zhang Peng li Desong wang Xiangwen Zhang li wang Jijun Zou Guozhu li State Key Laboratory of Metastable Materials Science and Technology(MMST) Hebei Key Laboratory of Applied ChemistryCollege of Environmental and Chemical EngineeringYanshan UniversityQinhuangdao 066004China Key Laboratory for Green Chemical Technology of Ministry of Education School of Chemical Engineering and TechnologyTianjin UniversityTianjin 300072China

Steam reforming of long-chain hydrocarbon fuels for hydrogen production has received great attention for thermal management of the hypersonic vehicle and fuel-cell *** this work,Pt catalysts supported on CeO_(2)and Tb-doped CeO_(2)were prepared by a precipitation *** physical structure and chemical properties of the as-prepared catalysts were characterized by powder X-ray diffraction,scanning electron microscopy,transmission electron microscopy,Raman spectroscopy,H_(2)temperature programmed reduction,and X-ray photoelectron *** results show that Tb-doped CeO_(2)supported Pt possesses abundant surface oxygen vacancies,good inhibition of ceria sintering,and strong metal-support interaction compared with CeO_(2)supported *** catalytic performance of hydrogen production via steam reforming of long-chain hydrocarbon fuels(n-dodecane)was *** with 2Pt/CeO_(2),2Pt/Ce_(0.9)Tb_(0.1)O_(2),and 2Pt/Ce_(0.5)Tb_(0.5)O_(2),the 2Pt/Ce_(0.7)Tb_(0.3)O_(2)has higher activity and stability for hydrogen production,on which the conversion of n-dodecane was maintained at about 53.2%after 600 min reaction under 700℃at liquid space velocity of 9 ml·g^(-1)·h^(-1).2Pt/CeO_(2)rapidly deactivated,the conversion of n-dodecane was reduced to only 41.6%after 600 min.

关键词： Steam reforming n-Dodecane Hydrogen production Pt-based catalyst Oxygen vacancy CeO_(2)

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Wind-sand flow simulation and radius optimization of highway embankment under different vertical curve radius

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Journal of Mountain Science 2024年第8期21卷 2533-2546页

作者： li liangying li Qi wang Xu XIN Guowei wang Zhenqiang School of Civil Engineering Lanzhou Jiaotong UniversityLanzhou 730070China

It is of great practical value to explore the correlation between the vertical curve radius of desert highway and the increase of sand accumulation in local lines,and to select the appropriate vertical curve radius for reducing the risk of sand *** this study,three-dimensional models of desert highway embankments with different vertical curve radii were constructed,and Fluent software was used to simulate the wind-sand flow field and sand accumulation distribution of vertical curve *** results show that:(1)Along the direction of the road,the concave and the convex vertical curve embankments have the effect of collecting and diverging the wind-sand flow,*** the radius of the concave vertical curve is 3000 m,5000 m,8000 m,10000 m and 20000 m,the wind velocity in the middle of the vertical curve is 31.76%,22.58%,10.78%,10.53%and 10.44%,higher than that at both *** the radius of the convex vertical curve is 6500 m,8000 m,10000 m,20000 m and 30000 m,the wind velocity at both ends of the vertical curve is 14.06%,9.99%,6.14%,3.22%and 2.41%,higher than that in the *** diversion effect also decreases with the increase of the radius.(2)The conductivity of the concave and convex vertical curve embankments with different radii is greater than 1,which is the sediment transport *** conductivity increases with the increase of radius and gradually tends to be *** the radius of the concave and convex vertical curves reaches 8000 m and 20000 m respectively,the phenomenon of sand accumulation is no longer *** the same radius condition,the concave vertical curve embankment is more prone to sand accumulation than the convex one.(3)Considering the strength of the collection and diversion of the vertical curve embankment with different radii,and the sand accumulation of the vertical curve embankment in the desert section of Wuma Expressway,the radius of the concave vertical curve is not less than 8000 m,and the r

关键词： Highway engineering Vertical curve Numerical simulation Embankment wind-sand flow Radius optimization

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Regulation effect of the grille spacing of a funnel-type grating water–sediment separation structure on the debris flow performance

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Journal of Mountain Science 2024年第7期21卷 2283-2304页

作者： li Shuai GU Tianfeng wang Jiading wang Fei li Pu State Key Laboratory of Continental Dynamics/Department of Geology Northwest UniversityXi’an 710069China Chengdu Institute of Mountain Hazards and Environment Ministry of Water Resources&Chinese Academy of SciencesChengdu 610299China

The size of pores or the grille spacing of water–sediment separation structures directly affects their regulation effect on the debris flow performance.A suitable pore size or grille spacing can effectively improve the water–sediment separation ability of the *** new funnel-type grating water–sediment separation structure(FGWSS)combines vertical and horizontal structures and provides a satisfactory water–sediment separation ***,the regulation effect of the grille spacing of the structure on the debris flow performance has not been *** regulation effect of the structure grille spacing on the debris flow performance is studied through a flume test,and the optimal structure grille spacing is *** empirical equation of the relationship between the relative grille spacing of the structure and the sediment separation rate is ***,the influence of the water–sediment separation structure on the regulation effect of debris flows is examined from two aspects:external factors(properties of debris flows)and internal factors(structural factors).The experimental results show that the gradation characteristics of solid particles in debris flows constitute a key factor affecting the regulation effect of the structure on the debris flow *** optimum grille spacing of the FGWSS matches the particle size corresponding to the material distribution curves d85~d90 of the debris *** total separation rate of debris flow particles is related to the grille spacing of the structure and the content of coarse and fine particles in the debris flow.

关键词： Debris flow Water–sediment separation structure Grille spacing Performance regulation effect

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Evaluating the stability and volumetric flowback rate of proppant packs in hydraulic fractures using the lattice Boltzmann-discrete element coupling method

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第6期16卷 2052-2063页

作者： Duo wang Sanbai li Rui wang Binhui li Zhejun Pan National Key Laboratory of Continental Shale Oil Northeast Petroleum UniversityDaqing163318China Institute of Unconventional Oil&Gas Northeast Petroleum UniversityDaqing163318China School of Environmental Science and Engineering Southern University of Science and TechnologyShenzhen518055China National Center for Applied Mathematics Shenzhen(NCAMS) Southern University of Science and TechnologyShenzhen518055China National Key Laboratory of Continental Shale Oil Daqing Oilfield of CNPCDaqing163002China Daqing Oilfield Exploration and Development Research Institute DaqingHeilongjiang163712China

The stability and mobility of proppant packs in hydraulic fractures during hydrocarbon production are numerically investigated by the lattice Boltzmann-discrete element coupling method(LB-DEM).This study starts with a preliminary proppant settling test,from which a solid volume fraction of 0.575 is calibrated for the proppant pack in the *** the established workflow to investigate proppant flowback,a displacement is applied to the fracture surfaces to compact the generated proppant pack as well as further mimicking proppant embedment under closure *** a pressure gradient is applied to drive the fluid-particle flow,a critical aperture-to-diameter ratio of 4 is observed,above which the proppant pack would *** results also show that the volumetric proppant flowback rate increases quadratically with the fracture aperture,while a linear variation between the particle flux and the pressure gradient is exhibited for a fixed fracture *** research outcome contributes towards an improved understanding of proppant flowback in hydraulic fractures,which also supports an optimised proppant size selection for hydraulic fracturing operations.

关键词： Numerical simulation Hydraulic fracturing Proppant flowback Closure stress Particulate flow

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