检索结果-南通市图书馆

Non-adiabatic holonomic quantum operations in continuous variable systems

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2024年第6期67卷 12-19页

作者： Hao-Long Zhang Yi-Hao Kang Fan Wu Zhen-biao yang shi-biao Zheng Fujian Key Laboratory of Quantum Information and Quantum Optics College of Physics and Information EngineeringFuzhou UniversityFuzhou 350116China

Quantum operations by utilizing the underlying geometric phases produced in physical systems are favoured due to their potential robustness.When a system in a non-degenerate eigenstate undergoes an adiabatically cyclic evolution dominated by its Hamiltonian,it will get a geometric phase,referred to as the Berry Phase.While a non-adiabatically cyclic evolution produces an Aharonov-Anandan geometric phase.The two types of Abelian geometric phases are extended to the non-Abelian cases,where the phase factors become matrix-valued and the transformations associated with different loops are non-commutable.Abelian and non-Abelian(holonomic)operations are prevalent in discrete variable systems,whose limited(say,two)energy levels,form the qubit.While their developments in continuous systems have also been investigated,mainly due to that,bosonic modes(in,such as,cat states)with large Hilbert spaces,provide potential advantages in fault-tolerant quantum computation.Here we propose a feasible scheme to realize non-adiabatic holonomic quantum logic operations in continuous variable systems with cat codes.We construct arbitrary single-qubit(two-qubit)gates with the combination of single-and two-photon drivings applied to a Kerr Parametric Oscillator(KPO)(the coupled KPOs).Our scheme relaxes the requirements of the previously proposed quantum geometric operation strategies in continuous variable systems,providing an effective way for quantum control.

关键词： cat qubit continuous variable systems non-Abelian

Detection of arboviruses in Culicoides(Diptera:Ceratopogonidae)collected from animal farms in the border areas of Yunnan Province,China

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Agriculture 2021年第9期20卷 2491-2501页

作者： DI Di LI Chen-xi LI Zong-jie WANG Xin XIA Qi-qi Mona SHARMA LI Bei-bei LIU Ke SHAO Dong-hua QIU Ya-feng Soe-Soe WAI yang shi-biao WEI Jian-chao MA Zhi-yong Shanghai Veterinary Research Institute Chinese Academy of Agricultural SciencesShanghai 200241P.R.China Yunnan Tropical and Subtropical Animal Virus Diseases Laboratory Yunnan Animal Science and Veterinary InstituteKunming 650224P.R.China Department of Veterinary Public Health University of Veterinary ScienceYezin 15013Myanmar

Biting midges of the genus Culicoides(order Diptera,family Ceratopogonidae)are potential biological vectors for the transmission of certain arboviruses among humans,livestock,and wild animals.This study collected a total of 405 Culicoides individuals from seven animal farms located in five counties in the border areas of Yunnan Province,China,and examined the Culicoides species composition and the major arboviruses carried by the Culicoides species.The collected Culicoides were classified into seven species with variable abundances:Culicoides arakawae(5.43%,22/405),Culicoides homotomus(1.23%,5/405),Culicoides obsoletus(19.75%,80/405),Culicoides orientalis(17.28%,70/405),Culicoides oxystoma(29.38%,119/405),Culicoides peregrinus(5.68%,23/405),and Culicoides nipponensis(21.23%,86/405).Among the seven species,C.oxystoma and C.nipponensis were distributed in all the five counties with abundances of 13.33–44.87%and 10.00–46.83%,respectively,suggesting that these were the dominant species of Culicoides widespread on animal farms in the border areas.PCR was used to detect major arboviruses in the collected Culicoides specimens,including bluetongue virus(BTV),Japanese encephalitis virus,Dengue virus,Zika virus,African swine fever virus,and African horse sickness virus.Among the tested viruses,only BTV serotype 1 was tested positive in C.oxystoma specimens collected from a buffalo farm.Culicoides oxystoma was the dominant species on animal farms in the sampled areas,but it has not previously been documented as positive for BTV in China.The current results thus suggest that C.oxystoma could be an important vector for BTV transmission in these border areas,which,however,needs to be confirmed by further comprehensive experiments.Overall,the present study provides the first profile of Culicoides species on animal farms in the China,Vietnam,and Myanmar border areas,establishes the prevalence of arboviruses carried by these Culicoides species,and suggests the vector potential of C.oxystoma species for the transmission of BTV.

关键词： biting midge Culicoides bluetongue virus arbovirus arthropod vector

Experimental observation of spontaneous symmetry breaking in a quantum phase transition

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2024年第2期67卷 34-39页

作者： Wen Ning Ri-Hua Zheng Jia-Hao Lu Fan Wu Zhen-biao yang shi-biao Zheng Fujian Key Laboratory of Quantum Information and Quantum Optics College of Physics and Information EngineeringFuzhou UniversityFuzhou 350108China Hefei National Laboratory Hefei 230088China

Spontaneous symmetry breaking(SSB)plays a central role in understanding a large variety of phenomena associated with phase transitions,such as superfluid and superconductivity.So far,the transition from a symmetric vacuum to a macroscopically ordered phase has been substantially explored.The process bridging these two distinct phases is critical to understanding how a classical world emerges from a quantum phase transition,but so far remains unexplored in experiment.We here report an experimental demonstration of such a process with a quantum Rabi model engineered with a superconducting circuit.We move the system from the normal phase to the superradiant phase featuring two symmetry-breaking field components,one of which is observed to emerge as the classical reality.The results demonstrate that the environment-induced decoherence plays a critical role in the SSB.

关键词： quantum phase transition Rabi model spontaneous symmetry breaking superconducting circuit Schrodinger cat states

Dynamic manipulation of multimodal emission in Er3+-activated non-core-shell structure for optical thermometry and information security

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2024年第4期43卷 1702-1712页

作者： Xuan Liu Zi-Xia Lin Yin-biao shi Xiao-Yan Wang Ming-Ye Ding Xiao-Fei yang College of Science Nanjing Forestry University Testing Center Yangzhou University

Regulating luminescent dynamics of lanthanide-based luminescent materials via external stimuli is of great significance in the fields of optical thermometry and high-level anti-counterfeiting.However,it is still a huge challenge to realize multimodal emissions with tunable color outputs from a single activator in simple structures via smart dynamic control of photon transition processes.Herein,we present a mechanistic strategy to achieve multimodal luminescence of Er3+activators with color-switchable outputs in a non-core-shell host.Under the control of excitation dynamics(λex=980,808,1532,377 nm),the population among the intermediate en ergy levels of Er3+and the interaction between Er3+and Yb3+could be precisely modulated through energy transfer and migration processes,leading to the generation of colortunable multimodal luminescence upon diverse excitation modes（non-steady-state,single-/dual-wavelength steady,thermal activation）.Inspired by its special luminescent performance,the as-obtained material exhibits great potential in noncontact thermometry,multimodal anticounterfeiting,and high-capacity information encryption by performing a series of proof-of-concept experiments.Our findings might provide a conceptual model to modulate the luminescent dynamics in a simple-structured system for the generation of color-adjustable multimodal emissions,which is convenient for the development of advanced luminescent materials toward versatile cuttingedge applications.

关键词： Lanthanide ions Multimodal emission Upconversion Downshifting Anti-counterfeiting Luminescent thermometry

Analyst Coverage,Forecasting Bias,and Corporate Innovation:Evidence from China

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Systems Science and Information 2024年第1期12卷 1-24页

作者： Xinping MA Yiru WANG Jianping LI biao shi School of Economics and Management University of Chinese Academy of SciencesBeijing 100049China School of Finance Nankai UniversityTianjin 300071China Institutes of Science and Development Chinese Academy of SciencesBeijing 100190China

Due to information asymmetry and strategic innovation,firms often encounter challenges related to insufficient driving forces and low-quality innovation outcomes.Analysts always act as information intermediaries who help foster the advancement of corporate innovation activities and the conversion of innovation output.This study examines the impact of analyst coverage and forecasting bias on corporate innovation,employing data from China A-shared listed firms spanning the period 2007 to 2019.We measure corporate innovation from two perspectives:Input and output.Specifically,we use the ratio of research and development(R&D)expenditure to sales as a proxy for the innovation input and the number of patent citations excluding self-citations to measure innovation output.We find that analyst coverage promotes corporate innovation,which is consistent with the“bright”side of analyst coverage.However,the positive effect of analyst coverage hinges on effectively transmitting and disclosing accurate information to investors in the capital market.Based on this,analysts'forecasting bias includes forecasting dispersion and optimism bias.We find evidence that an increase in analysts'forecast dispersion leads to a decrease in corporate innovation quality.Moreover,this paper presents a novel approach by employing the regression discontinuity method to examine the effect of analyst optimistic bias on firm innovation.The empirical findings reveal that overly optimistic forecasts by analysts exacerbate innovation quality.These analyses enrich the research on analyst coverage and corporate innovation,providing an empirical basis for improving the capital market with the help of analysts.

关键词： analyst coverage forecasting bias corporate innovation innovation quality

Pressure transient characteristics of non-uniform conductivity fractured wells in viscoelasticity polymer flooding based on oil-water two-phase flow

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2024年第1期21卷 343-351页

作者： yang Wang Jia Zhang shi-Long yang Ze-Xuan Xu shi-Qing Cheng National Key Laboratory of Petroleum Resources and Engineering China University of Petroleum(Beijing)Beijing102249China

Polymer flooding in fractured wells has been extensively applied in oilfields to enhance oil recovery.In contrast to water,polymer solution exhibits non-Newtonian and nonlinear behavior such as effects of shear thinning and shear thickening,polymer convection,diffusion,adsorption retention,inaccessible pore volume and reduced effective permeability.Meanwhile,the flux density and fracture conductivity along the hydraulic fracture are generally non-uniform due to the effects of pressure distribution,formation damage,and proppant breakage.In this paper,we present an oil-water two-phase flow model that captures these complex non-Newtonian and nonlinear behavior,and non-uniform fracture characteristics in fractured polymer flooding.The hydraulic fracture is firstly divided into two parts:high-conductivity fracture near the wellbore and low-conductivity fracture in the far-wellbore section.A hybrid grid system,including perpendicular bisection(PEBI)and Cartesian grid,is applied to discrete the partial differential flow equations,and the local grid refinement method is applied in the near-wellbore region to accurately calculate the pressure distribution and shear rate of polymer solution.The combination of polymer behavior characterizations and numerical flow simulations are applied,resulting in the calculation for the distribution of water saturation,polymer concentration and reservoir pressure.Compared with the polymer flooding well with uniform fracture conductivity,this non-uniform fracture conductivity model exhibits the larger pressure difference,and the shorter bilinear flow period due to the decrease of fracture flow ability in the far-wellbore section.The field case of the fall-off test demonstrates that the proposed method characterizes fracture characteristics more accurately,and yields fracture half-lengths that better match engineering reality,enabling a quantitative segmented characterization of the near-wellbore section with high fracture conductivity and the far-wellbore section with low fracture conduct

关键词： Polymer flooding Non-Newtonian fluid Non-uniform fracture conductivity Two-phase flow Pressure transient analysis

Research on the macro-and meso-mechanical properties of frozen sand mold based on Hertz-Mindlin with Bonding model

在线全文

学校读者我要写书评

暂无评论

Particuology 2024年第5期88卷 176-191页

作者： Jianpei shi Zhongde Shan Haoqin yang College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China College of Material Science and Technology Nanjing University of Aeronautics and AstronauticsNanjing 210016China

In this study,macro-and meso-mechanical properties of frozen sand molds were discussed based on the Hertz-Mindlin with Bonding(HMB)model.Plackett-Burman,steepest ascent,and central composite designs were utilized to propose a parameter calibration methodology.The effects of mesoscopic parameter variations on the compressive strength and average gradient of stress-strain were investigated through response surface method analysis.Results showed that the relative error between the simulated and measured repose angle is 3.1%under calibrated intrinsic contact parameters.The compressive strength and average stress-strain gradient primarily depend on the normal and shear stiffness per unit area,as well as the particle size and porosity of the silica sand.Furthermore,taking load-displacement curves of three frozen sand molds with different geometric characteristics as the target value,the reliability and effectiveness of the frozen sand mold HMB model were verified through uniaxial compression tests and discrete element simulations.

关键词： Frozen sand mold Hertz-Mindlin with Bonding model Uniaxial compression test Discrete element method Mechanical properties

Flow excitation mechanisms of unbalanced impeller forces after pump power-trip of ultra-high head pump-turbines

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2024年第5期67卷 1602-1611页

作者： FU XiaoLong LI DeYou LV JingWei yang biao WANG HongJie WEI XianZhu School of Energy Science and Engineering Harbin Institute of TechnologyHarbin150001China State Key Laboratory of Hydro-Power Equipment Harbin Institute of Large Electrical MachineryHarbin150040China

To elucidate the dynamic mechanisms of unbalanced impellers in ultra-high head pump-turbines(PTs),this study employed a one-and three-dimensional coupled method to simulate the pump power-trip(PPT)process of an ultra-high head PT.The investigation revealed two novel pulsation frequency components,denoted as fDVand fINFT,associated with impeller forces.The pulsation intensities of these components were markedly higher than those of rotor-stator interaction frequency components in ultra-high head PTs.Notably,the fDVcomponents exhibited pulsations at 1–2 times the rated rotation frequency of the impeller,spanning the entire transition period.Meanwhile,the fINFTcomponents constituted a complex frequency band with various frequency values,primarily occurring near conditions(Q=0,n=0,M=0,and d M/dt=0).These two pulsation frequency components were predominantly linked to the unsteady evolution of dean vortices inside the volute and complex transitions of the flow pattern within the impeller,respectively.It is crucial to note that these unbalanced flow-induced impeller axial forces can elevate the risk of accidents where the rotor is subjected to significant upwind axial forces.These findings offer valuable insights into mitigating the risk of rotor lifting due to axial forces during PT events in ultra-high head PTs.

关键词： ultra-high head pump-turbine pump power-trip unbalanced impeller forces pressure pulsations flow pattern transitions

Thermal Performance of a 4 K High-Frequency Pulse Tube Cryocooler with Different Working Fluids

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2024年第4期33卷 1468-1479页

作者： GAO Zhaozhao yang biao FAN Xiaoyu CHEN Liubiao WANG Junjie Key Laboratory of Cryogenic Science and Technology Technical Institute of Physics and ChemistryChinese Academy of Sciences University of Chinese Academy of Sciences

The high-frequency pulse tube cryocooler（HPTC） represents a promising miniature cryocooling technology due to its compact structure and the absence of low-temperature moving components.However,limited to the non-ideal gas effect of4He,the HPTC is hard to obtain high cooling performance in the liquid helium temperature range.3He as the working fluid can effectively improve the cooling performance of the HPTC,but the high cost hinders its wide application.In consideration of both cooling performance and cost-effectiveness,this paper explores the feasibility of utilizing3He-4He mixtures as the working fluid for HPTCs.Firstly,the experimental results of a developed HPTC based4He are reported.With a total power consumption of 575 W,the lowest temperature of 3.26 K was observed.And the measured cooling power at 4.2 K was 20.8 mW.Then the theoretical utmost efficiency of the cryocooler was calculated in terms of the thermophysical properties of the working fluids,using3He-4He mixtures with different compositions as the working fluids.The whole machine modeling of the HPTC was further carried out,and the influence of the working fluids with different components on the structural parameters such as double-inlet and inertance tube,and operating parameters such as pressure and frequency were analyzed.The calculated results show that the cooling power is expected to be increased to36 mW and 53 mW if the equimolar3He-4He mixture and pure3He are used,respectively.

关键词： high-frequency pulse tube cryocooler 3 He- 4 He mixture liquid helium temperature thermally coupled