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Consistency of Pantheon+supernovae with a large-scale isotropic universe

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Chinese Physics C 2023年第12期47卷 131-138页

作者：唐丽林海南刘亮李昕 Department of Math and Physics Mianyang Teachers'CollegeMianyang 621000China Department of Physics Chongqing UniversityChongqing 401331China chongqing Key Laboratory for Strongly Coupled Physics Chongqing UniversityChongqing 401331China Research Center of Computational Physics Mianyang Teachers'CollegeMianyang 621000China

We investigate the possible anisotropy of the universe using data on the most up-to-date type Ia supernovae,i.e.,the Pantheon+*** fit the full Pantheon+data with the dipole-modulated ΛCDM model and find that the data are well consistent with a null *** further divide the full sample into several subsamples with different high-redshift cutoffs *** is shown that the dipole appears at the 2σ confidence level only if z_(c)≤0.1,and in this redshift region,the dipole is very stable,almost independent of the specific value of *** z_(c)=0.1,the dipole amplitude is D=1.0_(-0.4^(+0.4))×10^(-3),pointing toward(l,b)=(334.5°_(-21.6°)^(+25.7°),16.0°_(-16.8°)^(+27.1°)),which is approximately 65°away from the CMB *** implies that the full Pantheon+sample is consistent with a large-scale isotropic universe,but the low-redshift anisotropy could not be purely explained by the peculiar motion of the local universe.

关键词： type Ia supernovae anisotropy cosmological parameters

AN INEQUALITY FOR SINGULAR VALUES OF MATRICES

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Chinese Science Bulletin 1992年第5期37卷 366-369页

作者：杨新民 Department of Mathematics Chongqing Teachers' College Chongqing 630047 PRC

Proof The proof of inequality (3)is by induction on m. For m= 2, inequality (3) holds from Lemma 1. Now suppose that inequality (3) holds for 2≤m≤r-1. By the induction hypothesis and Lemma 1, we

关键词： singular values matrix product estimation of the eigenvalues

Exponential stability of cellular neural networks with multiple time delays and impulsive effects

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Chinese Physics B 2008年第11期17卷 4091-4099页

作者：李东王慧杨丹张小洪王时龙 college of Mathematics and Physics Science Chongqing University Department of Mathematics Leshan Teachers' College college of Software Engineering Chongqing University State Key Laboratories of Mechanical Transmission Chongqing University

In this work, the stability issues of the equilibrium points of the cellular neural networks with multiple time delays and impulsive effects are investigated. Based on the stability theory of Lyapunov-Krasovskii, the method of linear matrix inequality （LMI） and parametrized first-order model transformation, several novel conditions guaranteeing the delaydependent and the delay-independent exponential stabilities are obtained. A numerical example is given to illustrate the effectiveness of our results.

关键词： cellular neural networks (CNNs) multi-delays exponential stability linear matrix inequality (LMI)

Inferring redshift and energy distributions of fast radio bursts from the first CHIME/FRB catalog

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Chinese Physics C 2023年第8期47卷 162-172页

作者：唐丽林海南李昕 Department of Math and Physics Mianyang Teachers’CollegeMianyang 621000China Department of Physics Chongqing UniversityChongqing 401331China chongqing Key Laboratory for Strongly Coupled Physics Chongqing UniversityChongqing 401331China

We reconstruct the extragalactic dispersion measure-redshift(DM_(E)-z)relation from well-localized fast radio bursts(FRBs)using Bayesian ***,the DM_(E)-z relation is used to infer the redshift and energy of the first CHIME/FRB *** find that the distributions of the extragalactic dispersion measure and inferred redshift of the non-repeating CHIME/FRBs follow a cut-off power law but with a significant excess at the low-redshift *** apply a set of criteria to exclude events that are susceptible to the selection effect,but the excess at low redshifts still exists in the remaining FRBs(which we call the gold sample).The cumulative distributions of fluence and energy for both the full sample and the gold sample do not follow the simple power law,but they can be well fitted by the bent power *** underlying physical implications require further investigation.

关键词： fast radio bursts intergalactic medium cosmological parameters

In Situ Laser Coating of Calcium Phosphate on TC4 Surface for Enhancing Bioactivity

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Journal of Iron and Steel Research International 2007年第3期14卷 73-78页

作者： DENG Chi WANG Yong ZHANG Ya-ping GAO Jia-cheng Department of Physics Leshan Teachers College Leshan 614004 Sichuan China School of Materials Science and Engineering Chongqing University Chongqing 400044 China

Titanium alloy has been a successful implant material owing to its excellent ratio of strength to weight, toughness, and bio-inert oxide surface. Significant progress has been made in improving the bioactivity of titanium alloy by coating its oxide surface with calcium phosphates. In the present study, in situ coating was reported on Ti6Al4V（TC4） surface with calcium phosphate （Ca-P） bioceramics synthesized and synchronously cladded by laser beam. This coating was grown by first preplacing directly the raw powders, which contain 80% of CaHPO4 · 2H2O, 20% of CaCO3, and dram of rare earth （RE）, on the TC4 surfaces, and then exposing the surfaces to the laser beam with a power density of 12. 73-15.27 MW · m^-2 and a scanning velocity of 10.5 m/s. The resultant coating was characterized using scanning electron microscopy （SEM）, X-ray diffraction （XRD）, thermogravimetric analysis and Different-thermal Scanning （TG-DSC）, and Energy Dispersive X-ray Detection （EDX）. The results show that these laser ceramics include hydroxyapatite （HA）, tricalcium phosphate （TCP）, Ca2 P2 O7, and other Ca-P phases, and the interface between the coating and the TC4 substrate has tighter fixation, in which the chemical bonding is approved. These laser hybrid coatings are useful in enhancing the bioactivity of titanium alloy surfaces.

关键词： titanium alloy surface calcium phosphate ceramics laser cladding bioactivity

Quantitative characterization of granular size segregation: A critical review

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PARTICUOLOGY 2024年第12期95卷 166-177页

作者： Leng, Cong Sun, Chengfeng Liao, Zhehan Xu, Jian chongqing Univ Coll Mat Sci & Engn Chongqing 400044 Peoples R China

Granular size segregation is an inevitable phenomenon in both natural and industrial processes. To understand the underlying mechanisms and develop effective optimization strategies, it is essential to employ robust methodologies that can quantitatively characterize and evaluate size segregation behaviors in granular systems. This review critically examines a wide variety of state-of-the-art methodologies from recent studies to quantify granular size segregation. The features of these methodologies are extracted and organized into a comprehensive framework. Four key questions are thoroughly discussed: evaluation criteria for identical segregation states, sensitivity to sample size, the influence of sampling division pattern, and the capability of handling multiple-component system. Finally, we provide an outlook on the future development of advanced and effective methodologies for granular size segregation characterization. (c) 2024 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

关键词： Granular system Size segregation Quantitative characterization Multi-scale framework

The Time-Dependence Growth of Metallic Crystal Ultrafine Particles

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Chinese Physics Letters 1992年第12期9卷 653-655页

作者： LIU Cunye DENG Zhaojing Department of Physics Southwest China Teachers UniversityChongqing 630715

By using x-ray diffraction technique and transmission electron microscopy the in situ growth property of metal crystal ultrafine particles(CUFP)which are deposited on the silica-substrates have been studied *** is found that the diffraction intensity and the nucleus diameter of Ag CUFP are grown with time by ***,the changes of crystal nucleus and the structure of Ag CUFP with time shows a crystallization trend,at the same time,the in situ growth of Ag CUFP displays a self-similarity character.

关键词： Crystal property crystallization

A Way of Extending Theorem in Group Theory

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Chinese Science Bulletin 1993年第11期38卷 884-887页

作者：陈重穆 Department of Mathematics Southwest Teachers UniversityChongqing 630715 PRC

Throughout this note, groups are all finite. N. It has established the following theorem concerning nilpotent groups It Theorem. Suppose that G is a group of odd order. (ⅰ) If the subgroups of prime order of G all are contained in the center of G, then G is nilpotent. (ⅱ) If the subgroups of prime order of G’all are normal in G, then G is solvable.

关键词： group theory nilpotent solvable.

Water-Air Mixing Jet Produced by Electro-hydraulic Impulse Technology Strengthening the Quality of Surface of Metal Materials

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Journal of Materials Science & Technology 2002年第3期18卷 194-196页

作者： Zhenfang LIAO and Shijin ZHANGcollege of Mechanical Engineering, chongqing University, chongqing 400044, China [ Manuscript received September 10, 2001, in revised form October 26, 2001] chongqing Univ Coll Mech Engn Chongqing 400044 Peoples R China

Electro-hydraulic impulse water-air mixing jet by which the quality of metal materials can be improved is described in this paper. The experimental results proved that the hardness and the micro-hardness of the surface layer of metal materials can be improved with this method, for example, the microhardness of CrWMn can be increased by 35.62 percent.

关键词： Electro-hydraulic impulse Water-air mixing jet Quality of surface