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Lipschitz-continuity of Spherically Convex Functions

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Acta Mathematica Sinica,English Series 2023年第2期39卷 363-374页

作者： Yin zhang qi GUO department of Mathematics Suzhou University of Science and TechnologySuzhou215009China

In this article,some basic and important properties of spherically convex functions,such as the Lipschitz-continuity,are *** is shown that,under a weaker condition,every family of spherically convex functions is equi-Lipschitzian on each closed spherically convex subset contained in the relative interior of their common domain,and from which a powerful result is derived:the pointwise convergence of a sequence of spherically convex functions implies its uniform convergence on each closed spherically convex subset contained in the relative interior of their common domain.

关键词： Spherically convex set spherically convex function Lipschitz-continuity uniform convergence

On Permutation Polynomials in Two Variables over ■/p^2■

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Acta Mathematica Sinica,English Series 2009年第7期25卷 1191-1200页

作者： qi Jiao WEI qi Fan zhang College of Mathematics Sichuan University Chengdu 610064 P. R. China Chengdu University of Information Technology Chengdu 610059 P. R. China

We give a good characterization of the permutation polynomials in two variables over Z/p2Z.

关键词： permutation polynomial Witt polynomial Witt vector ring

Alternative flexible correction forming of a blade: multipoint correction with surface measurement and deformation simulation

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Advances in Manufacturing 2023年第4期11卷 587-600页

作者： Da-Wei zhang Wen-Long Gao-zhang qi zhang Xi’an Key Laboratory of Intelligent Equipment and Control School of Mechanical EngineeringXi’an Jiaotong UniversityXi’an710049People’s Republic of China

Distortion during the forging or machining processes of a blade causes problems in subsequent manufacturing. This paper proposes an alternative multipoint correction method integrated with blade measurement, determination of correcting parameters, and adjustment of the correcting die. An iterative algorithm for determining the correcting parameters is proposed. Measuring equipment combining a laser displacement sensor with multipoint flexible support is manufactured to measure the blade shape. Multipoint correcting equipment with an adaptive lower die and rapid adjustment is manufactured, and software is developed for data analysis and equipment control. The correction experiment for a rough-machined steam-turbine blade indicates that the correcting parameters can be determined after one modification based on numerical simulation, and that a rough blade that meets the allowance for finish machining can be obtained using the determined correction parameters.

关键词： Blade Surface measurement Numerical simulation Multipoint correction

The Photoionization of Atomic Hydrogen in an Intense Circularly Polarized Laser Field

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Communications in Theoretical Physics 2001年第12期36卷 685-690页

作者： zhang deng zhang qi-Ren department of Technical Physics Peking University Beijing 100871 China Department of Technical Physics Peking University Beijing 100871 China

We calculate nonperturbatively the irfluence of a strong circularly polarized laser beam on the hydrogen atom energy levels by making use of the time-independent formalism proposed by one of us. The photoionization cross section of the hydrogen atom irradiated by this laser beam and the angular distribution of photoelectrons are also calculated. From the numerical results we clearly see the intensity dependence of the whole photoionization process,including the intensity dependence of the photoelectron energies.

关键词： intensity dependence of photoelectron energies, photoionization, atomic hydrogen

Noise-Induced Entanglement Transition in One-Dimensional Random Quantum Circuits

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Chinese Physics Letters 2022年第5期39卷 10-15页

作者： qi zhang Guang-Ming zhang State Key Laboratory of Low-Dimensional Quantum Physics and department of Physics Tsinghua UniversityBeijing 100084China Frontier Science Center for Quantum Information Beijing 100084China

A random quantum circuit is a minimally structured model to study entanglement dynamics of many-body quantum *** consider a one-dimensional quantum circuit with noisy Haar-random unitary gates using density matrix operator and tensor contraction *** is shown that the entanglement evolution of the random quantum circuits is properly characterized by the logarithmic entanglement *** performing exact numerical calculations,we find that,as the physical error rate is decreased below a critical value p;≈0.056,the logarithmic entanglement negativity changes from the area law to the volume law,giving rise to an entanglement *** critical exponent of the correlation length can be determined from the finite-size scaling analysis,revealing the universal dynamic property of the noisy intermediate-scale quantum devices.

关键词： transition quantum Transition

A Novel High Sensitivity Refractive Index Sensor Based on Multi-Core Micro/Nano Fiber

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Photonic Sensors 2019年第3期9卷 197-204页

作者： Yuefeng qi Jin zhang qi FENG Xin zhang Yanyan LIU Ying HAN School of Information Science and Engineering Yanshan University Qinhuangdao 066004 China Key Laboratory for Special Fiber and Fiber Sensor of Hebei Province Qinhuangdao 066004 China BaYin GuoLeng Vocational and Technical College Korla 841000 China

A refractive index sensor based on a multi-core micro/nano fiber is proposed for low refractive index solutions. At first, the mode field distribution of the tapered multi-core fiber is analyzed with the finite element model (FEM). After that, the relationship between the refractive index sensitivity and the diameter of the multi-core micro/nano fiber is calculated. At last, four sensors with different sizes are explored, and when the taper length is 16.20 mm, the refractive index sensitivity of the sensor can reach 5815.50nm/RIU, which agrees with the theoretical analysis. The refractive index measurement error is less than 0.5 %o, which has a high practical application value. The longer the taper length is, the smaller the fiber diameter is. According to the theoretical analysis, when the fiber diameter is less than 4.864 gm, the structure sensor\ refractive index sensitivity is higher than 10000 nm/RIU. At the same time, when the sensor's taper length is 15.99 mm, its temperature sensitivity is -0.1084nm/°C. Compared with single-mode fiber, the sensor proposed here has the advantages of stability, compact structure, and high sensitivity, which has a potential in the field of seawater salinity measurement.

关键词： Fiber optic sensor refractive index measurement multi-core fiber

Preparation of Highly Loaded PAA/PAH Layer-by-layer Films by Combining Acid Transformation and Templating Methods

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Chemical Research in Chinese Universities 2019年第2期35卷 353-358页

作者： XIA qi PAN Shaofeng zhang Yi AN qi zhang qian zhang Yihe Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes National Laboratory of Mineral MaterialsSchool of Materials Science and TechnologyChina University of GeosciencesBeijing 100083P.R.China School of Resources and Environmental Engineering Shandong University of TechnologyZibo 255049P.R.China

Enhancing the molecular loading capability of layer-by-layer(LbL)method holds high importance in environmental and biomedical ***,we reported a strategy to prepare highly loaded poly(acrylic acid)(PAA)/poly(allylamine hydrochloride)(PAH)LbL films by combining the particulate templating strategy and acid treatment film transformation and realized tlae efficient loading of hydrophilic small *** loaded molecules can be released in a pH-controlled manner.A slow release speed was observed in the acidic solutions with pH value of *** releases were observed at higher pH values(5 or 7).

关键词： Layer-by-layer High load Calcium carbonate template pH-Controlled release

Experimental study and industrial demonstration on utilization of Fe,Ti and V from vanadium-bearing titanomagnetite ore sands

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Journal of Iron and Steel Research International 2019年第12期26卷 1295-1303页

作者： Jing Gu Li Wang de-hong Xia Feng zhang Zhao-dong qi Wen-qing Ao School of Energy and Environmental Engineering University of Science and Technology BeijingBeijing 100083China Beijing Key Laboratory of Advanced Ceramic and Refractories China Iron&Steel Research Institute GroupBeijing 100081China

In order to achieve highly efficient utilization of three valuable elements Fe,Ti and V simultaneously from vanadium-bearing titanomagnetite ore sands,an improved carbothermic reduction method was proposed and verified in both laboratory scale and industrial test-bed *** method combined the process of direct reduction and the process of further reduction and ***,pulverized coal injection was *** experimental tests,the effects of parameters such as carbon content in briquette,reduction duration and reduction temperature on the contents of metallic Fe and FeO as well as Fe metallization rate were *** results indicated that Fe metallization rate in the carbon-containing briquette could reach 75.83%.In the industrial test-bed tests,the effects of carbon content in briquette,reduction duration and reduction temperature were also investigated,*** addition,processes with and without pulverized coal injection were *** comparative analysis indicated that the content of TiO2 in titaniferous slag was increased by applying pulverized coal injection,and it can reach 82.5 wt.%.Meanwhile,the energy performance analysis showed that the equivalent electricity consumption of the test-bed dropped significantly to 2071 kWh per ton of slag,about 26.0%less than that of traditional ***,the investment payback of the test-bed is 3.4 *** experiments and industrial test-bed tests demonstrated that the proposed method has the advantages of highly efficient utilization,high energy efficiency as well as good economic performance.

关键词： Vanadium titanomagnetite Titaniferous slag Rotary hearth furnace Direct reduction Industrial test-bed

Grant-Free Random Access in Pilot-Reused Multicell Massive MIMO Systems with Backoff Mechanisms

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China Communications 2023年第9期20卷 185-195页

作者： qi zhang Jun zhang Shi Jin Jiangsu Key Laboratory of Wireless Communications Nanjing University of Posts and TelecommunicationsNanjing 210003China National Mobile Communications Research Laboratory Southeast UniversityNanjing 210096China

Grant-free random access(RA)is attractive for future network due to the minimized access *** this paper,we investigate the grantfree RA in multicell massive multiple-input multipleoutput(MIMO)systems with pilot *** backoff mechanism,user equipments(UEs)in each cell are randomly activated,and active UEs randomly select orthogonal pilots from a predefined pilot pool,which results in a random pilot contamination among *** the help of indicators that capture the uncertainties of UE activation and pilot selection,we derive a closed-form approximation of the spectral efficiency per cell after averaging over the channel fading as well as UEs’random *** on the analysis,the optimal backoff parameter and pilot length that maximize the spectral efficiency can be *** find that the backoff mechanism is necessary for the system with large number of UEs,as it can bring significant gains on the spectral ***,as UE number grows,more backoff time is needed.

关键词： backoff mechanism grant-free RA multicell massive MIMO