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A Result on the Quasi-periodic Solutions of Forced Isochronous Oscillators at Resonance

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Chinese Annals of Mathematics,Series B 2015年第4期36卷 523-542页

作者： Bin liu Yingchao TANG LMAM School of Mathematical Sciences Peking University

In this paper, the authors are concerned with the forced isochronous oscillators with a repulsive singularity and a bounded nonlinearity x'' + V'(x) + g(x) = e(t, x, x'),where the assumptions on V, g and e are regular, described precisely in the *** a variant of Moser's twist theorem of invariant curves, the authors show the existence of quasi-periodic solutions and boundedness of all solutions. This extends the result of liu to the case of the above system where e depends on the velocity.

关键词： Isochronous oscillators Repulsive singularity Invariant curves Timereversibility Quasi-periodic solutions Lazer-Landesman conditions Boundedness of solutions

The unitary subgroups of group algebras for a class of finite 2-groups with the derived subgroup of order 2

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Science China Mathematics 2024年第9期67卷 1989-2018页

作者： Yulei Wang Heguo liu Department of Mathematics Henan University of TechnologyZhengzhou 450001China Department of Mathematics Hainan UniversityHaikou 570228China

Let p be a prime and F be a finite field of characteristic *** that FG is the group algebra of the finite p-group G over the field *** V(FG)denote the group of normalized units in FG and let V_(*)(FG)denote the unitary subgroup of V(FG).If p is odd,then the order of V_(*)(FG)is|F|^((|G-1)/2).However,the case p=2 still is *** this paper,the order of V*(FG)is computed when G is a nonabelian 2-group given by a central extension of the form 1→Z_(2^(n))×Z_(2^(m))→G→Z_(2)×…×Z_(2)→1 and G'≌Z_(2),n,m≥***,a conjecture is confirmed,i.e.,the order of V_(*)(FG)can be divisible by|F|^(1/2(|G|+|Ω1(G)|)-1),where Ω_(1)(G)={g∈G|g^(2)=1}.

关键词： normalized unit unitary subgroup inner abelian p-group central extension

Organic geochemistry and petrology of source rocks from the Banqiao Sag, Bohai Bay Basin, China: Implications for petroleum exploration

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Petroleum Science 2022年第4期19卷 1505-1515页

作者： Xiang-Bai liu Guang-Di liu Wen-Ya Jiang Ze-Zhang Song Na Wang State Key Laboratory of Petroleum Resources and Prospecting China University of PetroleumBeijing102249China College of Geosciences China University of PetroleumBeijing102249China Exploration and Development Research Institute Dagang Oilfield CompanyPetroChinaTianjin300280China

The organic geochemistry and petrology of source rocks determine the hydrocarbon generation potential of the Banqiao Sag. In this study, organic geochemistry and petrology were used to determine the abundance of organic matter(OM), OM type, OM maturity, and sedimentary environments of the source rocks, collected from Cenozoic Shahejie Formation, Banqiao Sag, Bohai Bay Basin, China. Vitrinite and liptinite are the main maceral composition of the source rocks, and range from 18% to 81% and from 2% to82% on a mineral matter free(MMF) basis, respectively. The values of vitrinite reflectance(Ro)(0.36%-1.20%) and the Tmaxvalues(397-486.C) show that the thermal maturity range from low mature to peak-maturity. The abundance of OM varies between 0.22% and 4.37%, suggesting that the source rocks of the Shahejie(Es) Formation are mainly fair to good source rocks. The Rock-Eval pyrolysis results show that the source rocks have good petroleum generation potential. The amount of free hydrocarbons(S_1)and hydrocarbons generated from pyrolysis(S_(2)) range within 0.01-3.70 mg/g, and 0.04-29.17 mg/g. The hydrogen index(HI) varies between 18.18 and 741.13 mg HC/g TOC, with most of the samples appearing to be mainly Type II kerogen, and thereby exhibiting the ability to generate both oil and gas. The ratios of Pr/Ph, the cross plot of Pr/nC_(17)-Ph/nC_(18), the cross plot of C_(29)/C_(27)-Pr/Ph, and ternary of dibenzothiophene, dibenzofuran, and fluorene, indicate that the Shahejie Formation deposited in suboxic and weak reducing environments. The main biological source is from advanced plants. The maceral composition and rock pyrolysis data indicate the kerogen type is a humic type or mixed sapropelic-humic type. The source rocks of the Shahejie(Es) Formation occur in the oil window, and the abundant organic richness,humic kerogen demonstrate that these rocks are effective oil and gas source rocks. The mudstone rocks in the Shahejie Formation are the main source of oil and gas and re

关键词： Lacustrine source rocks Petrology Biomarkers Depositional environment Banqiao Sag

Parity-check and G-matrix based intelligent early stopping criterion for belief propagation decoder for polar codes

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Digital Communications and Networks 2023年第5期9卷 1148-1156页

作者： Qasim Jan Shahid Hussain Zhiwen Pan Nan liu Zakir Ali Zechen liu Xiaohu You National Mobile Communications Research Laboratory Southeast UniversityNanjingJiangsu210096China Purple Mountain Laboratories NanjingJiangsu211100China Department of Computer Science COMSATS University IslamabadAttock CampusAttock43600Pakistan School of Medicine Computer Science and EngineeringUniversity of GalwayH91 TK33GalwayIreland Department of Computer Sciences Bahria University Lahore Campus54600Pakistan

The error correction performance of Belief Propagation(BP)decoding for polar codes is satisfactory compared with the Successive Cancellation(SC)***,it has to complete a fixed number of iterations,which results in high computational *** necessitates an intelligent identification of successful BP decoding for early termination of the decoding process to avoid unnecessary iterations and minimize the computational complexity of BP *** paper proposes a hybrid technique that combines the“paritycheck”with the“G-matrix”to reduce the computational complexity of BP decoder for polar *** proposed hybrid technique takes advantage of the parity-check to intelligently identify the valid codeword at an early stage and terminate the BP decoding process,which minimizes the overhead of the G-matrix and reduces the computational complexity of BP *** explore a detailed mechanism incorporating the parity bits as outer code and prove that the proposed hybrid technique minimizes the computational complexity while preserving the BP error correction ***,mathematical formulation for the proposed hybrid technique that minimizes the computation cost of the G-matrix is *** performance of the proposed hybrid technique is validated by comparing it with the state-of-the-art early stopping criteria for BP *** results show that the proposed hybrid technique reduces the iterations by about 90%of BP decoding in a high Signal-to-Noise Ratio(SNR)(i.e.,3.5~4 dB),and approaches the error correction performance of G-matrix and conventional BP decoder for polar codes.

关键词： Belief propagation Early termination G-matrix Parity-check Polar codes

HEATING RATE OF MINERALS AND COMPOUNDS IN MICROWAVE FIELD

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Transactions of Nonferrous Metals Society of China 1996年第1期6卷 35-40页

作者： Hua Yixiru liu Chunpeng Department oj Metallurgy Kimming University of Science and Technology、Kunming 650093

More than 40 kinds of selected minerals and compounds were individually irradiated by microwaves under an inert atmosphere,and the temperatures of samples were measured with a metal-sheathed thermocouple inserted into the samples *** results indicated that most sulphide and some oxide minerals and compounds could be heated to high temperatures in a short timet whereas the common gangue minerals,some oxide and oxy-salt minerals or compounds could *** sulphide minerals had faster heating rate than the oxide minerals containing the same *** impurities of minerals had significant effect on the heating *** selective heating characteristics of microwaves on different minerals and compounds could be attributed to the differences between their conductivities or dielectric loss factors and bonding properties.

关键词： microwave heating minerals and compounds mineral processing extractive metallurgy

High pressure equation of state for molten CaCO_3 from first principles simulations

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Chinese Journal Of Geochemistry 2015年第1期34卷 13-20页

作者： Zhigang Zhang Zairong liu Key Laboratory of Earth and Planetary Physics Institute of Geology and Geophysics Chinese Academy of Sciences

Carbonate melts are important active metasomatic agents and efficient transport agents; their thermodynamic properties at high temperatures and pressures are therefore of considerable interest for various geochemica applications. However, due to the extreme challenges in relevant experiments, current knowledge of even the density of carbonate melts is limited. In this study, we provide high quality volumetric data of Ca CO3-melt from firs principles at high temperatures and pressures(up to3,500 K and 60 GPa). The accuracy of these data is demonstrated through comprehensive comparison with available experimental data and a thorough discussion of the predictability of the re-scaling method proposed in this study. Based on the simulations, an equation of state has been established that is critical to relevant highly disputed questions such as the decomposition and solidification boundaries of Ca CO3 melts, the latter of which is briefly discussed in this study with a newly derived ab initio melting curve to high pressures.

关键词：熔融曲线第一原理碳酸钙高压力模拟实验数据热力学性质 CaCO3

INVESTIGATION ON APPLICABILITY OF VARIOUS STRESS DEFINITIONS IN ATOMISTIC SIMULATION

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Acta Mechanica Solida Sinica 2009年第6期22卷 644-649页

作者： Ran Xu Bin liu AML Department of Engineering Mechanics Tsinghua University Beijing 100084 China

How to correctly extract Cauchy stress from the atomistic simulations is a crucial issue in studying the mechanical behaviours of atomic systems, but is still in controversy. In this paper, three typical atomistic simulation examples are used to validate various existing stress definitions. It is found that the classical virial stress fails in predicting the stresses in these examples, because the velocity depends on the choice of the local average volume or the reference frame velocity and other factors. In contrast, the Lagrangian cross-section stress and Lagrangian virial stress are validated by these examples, and the instantaneous Lagrangian atomic stress definition is also proposed for dynamical problems.

关键词： atomic stress virial stress atomistic simulation

Functionalization of Carbonyl Compounds via Photoredox Organocatalysis

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Chinese Journal of Chemistry 2017年第10期35卷 1491-1500页

作者： Yuhua liu Wen Dong School of Chemistry and Chemical Engineering Guangzhou University Guangzhou Guangdong 510006 China

In recent years, a methodology merging photoredox catalysis with organocatalysis termed ＂photoredox organo- catalysis＂ has emerged to allow the direct, selective and efficient functionalization of the α/β-C of carbonyl com- pounds under mild reaction condition. In this review, photophysics background of photoredox catalysis is intro- duced, followed by a report on recent advances in direct α- and β-functionalization of carbonyls with photoredox organocatalysis methodology. With this different reaction modes, valuable synthetic targets including different a/fl-functionalized carbonyls are accessible.

关键词： photoredox organocatalysis functionalization of carbonyl compounds

Effect of brain-derived neurotropic factor released from hypoxic astrocytes on gamma-aminobutyric acid type A receptor function in normal hippocampal neurons

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Neural Regeneration Research 2011年第25期6卷 1954-1959页

作者： Hongliang liu Tijun Dai Department of Anesthesiology Chongqing Cancer Institute/Cancer Hospital Chongqing 400030 China Department of Anesthesiology Xuzhou Medical College Xuzhou 221002 Jiangsu Province China

Astrocytes can release increased levels of brain-derived neurotrophic factor during cerebral ischemia, but it is unclear whether brain-derived neurotrophic factor affects y-aminobutyric acid type A receptor function in normal neurons. Results from this study demonstrated that y-aminobutyric acid at 100 pmol/L concentration raised the intracellular calcium level in neurons treated with medium from cultured hypoxic astrocytes, and the rise in calcium level could be inhibited by y-aminobutyric acid type A receptor antagonist bicuculline or brain-derived neurotrophic factor receptor antagonist k252a, y-aminobutyric acid type A-gated current induced by 100 IJmol/L y-aminobutyric acid was in an inward direction in physiological conditions, but shifted to the outward direction in neurons when treated with the medium from cultured hypoxic astrocytes, and this effect could be inhibited by k252a. The reverse potential was shifted leftward to -93 mV, which could be inhibited by k252a and Na＋-K＋-CI cotransporter inhibitor bumetanide. Brain-derived neurotrophic factor was released from hypoxic astrocytes at a high level. It shifted the reverse potential of y-aminobutyric acid type A-gated currents leftward in normal neurons by enhancing the function of Na＋-K＋-CI- cotransporter, and caused y-aminobutyric acid to exert an excitatory effect by activating y-aminobutyric acid type A receptor.

关键词： brain-derived neurotrophic factor hypoxia astrocytes neurons y-aminobutyric acid type A receptor Na+-K+-CI cotransporter