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Constraints of f(R) gravity in Palatini approach with observational Hubble data

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Science china(physics,Mechanics & Astronomy) 2011年第8期54卷 1378-1383页

作者： ZHAI ZhongXu & liu WenBiao Department of physics, institute of theoretical physics, Beijing Normal university, Beijing 100875, china 1. Department of physics Institute of Theoretical Physics Beijing Normal University Beijing 100875 China

We use the newly released observational H(z) data (OHD), the Cosmic Microwave Background (CMB) shift parameter, and the Baryon Acoustic Oscillation (BAO) measurements data to constrain cosmological parameters of f(R) gravity in Palatini formalism in which the f(R) form is defined as f(R) = R β/Rn. Under the assumption of a spatially flat FRW universe, we get the best fitting results of the free parameters (Ωm0, n). In the calculation, we marginalize the likelihood function over H0 by integrating the probability density P ∝ e-χ2/2 to obtain the best fitting results and the confidence regions in the Ωm0-n plane. The constraints results of (Ωm0, n) = (0.33, 0.41) by OHD only and (Ωm0, n) = (0.23, 0.08) by the combination of OHD+CMB+BAO both indicate that the universe goes through three last phases, i.e., radiation dominated, matter-dominated, and late time accelerated expansion without introduction of dark energy.

关键词： f(R) gravity OHD CMB BAO accelerating expansion dark energy

Experimental Study on Ammonia Co-Firing with Coal for Carbon Reduction in the Boiler of a 300-MW Coal-Fired Power Station

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Engineering 2024年第9期40卷 247-259页

作者： Qifu Lin Wangping Sun Haiyan Li Yangjiong liu Yuwei Chen chengzhou liu Yiman Jiang Yu Cheng Ning Ma Huaqing Ya Longwei Chen Shidong Fang Hansheng Feng Guang-Nan Luo Jiangang Li Kaixin Xiang Jie Cong Cheng Cheng institute of Energy Hefei Comprehensive National Science Center(Anhui Energy Laboratory)Hefei 230088China Anbang Technology Co.Ltd Tongling 244000China institute of Plasma physics Hefei Institute of Matter ScienceChinese Academy of SciencesHefei 230031China

To reduce CO_(2) emissions from coal-fired power plants,the development of low-carbon or carbon-free fuel combustion technologies has become *** a new zero-carbon fuel,ammonia(NH_(3))can be used to address the storage and transportation issues of hydrogen *** it is not feasible to completely replace coal with ammonia in the short term,the development of ammonia-coal co-combustion technology at the current stage is a fast and feasible approach to reduce CO_(2) emissions from coal-fired power *** study focuses on modifying the boiler and installing two layers of eight pure-ammonia burners in a 300-MW coal-fired power plant to achieve ammonia-coal co-combustion at proportions ranging from 20%to 10%(by heat ratio)at loads of 180-to 300-MW,*** results show that,during ammonia-coal co-combustion in a 300-MW coal-fired power plant,there was a more significant change in NO_(x) emissions at the furnace outlet compared with that under pure-coal combustion as the boiler oxygen levels ***,ammonia burners located in the middle part of the main combustion zone exhibited a better high-temperature reduction performance than those located in the upper part of the main combustion *** all ammonia co-combustion conditions,the NH_(3) concentration at the furnace outlet remained below 1 parts per million(ppm).Compared with that under pure-coal conditions,the thermal efficiency of the boiler slightly decreased(by 0.12%-0.38%)under different loads when ammonia co-combustion reached 15 t·h^(-1).Ammonia co-combustion in coal-fired power plants is a potentially feasible technology route for carbon reduction.

关键词： Coal-fired boiler Coal mixing with ammonia Ammonia-coal co-firing Nitrogen oxide(NO_(x)) CO_(2)reduction Boiler thermal efficiency

Lookback time as a test for f(R) gravity in the Palatini approach

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Research in Astronomy and Astrophysics 2011年第11期11卷 1257-1265页

作者： Zhong-Xu Zhai and Wen-Biao liu Department of physics, institute of theoretical physics, Beijing Normal university, Beijing 100875, china Department of physics Institute of Theoretical Physics Beijing Normal University Beijing 100875 China

We use the recently released data of lookback time (LT)-redshift relation, the cosmic microwave background shift parameter and the baryon acoustic oscillation measurements to constrain cosmological parameters of f (R) gravity in the Palatini formalism by considering the f (R) form of type (a) f (R) = R β/Rn and (b) f (R) = R + α ln R β. Under the assumption of a Friedmann-Robertson-Walker universe, we achieved the best fitting results of the free parameters (Ωm0, n) for (a) and (Ωm0, α) for (b). We find that current LT data can provide interesting and effective constraints on gravity models. Compared with other data, the LT constraints favor a smaller value of the non-relativistic matter energy density.

关键词： cosmology cosmic microwave background

The lepton flavor violating signal of the extra gauge boson Z′in photon-photon collision at the ILC

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Science china(physics,Mechanics & Astronomy) 2010年第11期53卷 1992-1997页

作者： liu GuoLi 1,2 1 physics Department,Zhengzhou university,Zhengzhou 450001,china 2 Kavli institute for theoretical physics china,Chinese Academy of Sciences,Beijing 100190,china 1. physics Department Zhengzhou University Zhengzhou 450001 China2. Kavli Institute for Theoretical Physics China Chinese Academy of Sciences Beijing 100190 China

The hitherto unconstrained lepton flavor mixings,induced by the new gauge boson Z ,which are the prediction of many new physics models,such as topcolor-assisted technicolor (TC2) models and flavor-universal TC2 models,may lead to the lepton flavor violating productions of τμˉ,τeˉ and μeˉ in photon-photon collision at the proposed International Linear Collider (ILC).Through a comparative analysis of these processes,we find that the better channel to probe the new physics models is the production of τμˉ or τeˉ which occurs at a much higher rate than μeˉ production due to the large mixing angle and the large flavor changing coupling,and may reach the detectable level of the ILC for a large part of the parameter *** the rates predicted by the Standard Model are far below the detectable level,these processes may serve as a sensitive probe for such new physics models.

关键词： new gauge boson Z lepton flavor violating processes photon-photon

Hawking radiation and thermodynamics of a Vaidya-Bonner black hole

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Research in Astronomy and Astrophysics 2010年第1期10卷 33-38页

作者： Zhen-Feng Niu Wen-Biao liu Department of physics Hebei North University Zhangjiakou 075000 China Department of physics Institute of Theoretical Physics Beijing Normal University Beijing 100875 China

Using Parikh＇s tunneling method, the Hawking radiation on the apparent horizon of a Vaidya-Bonner black hole is calculated. When the back-reaction of particles is neglected, the thermal spectrum can be precisely obtained. Then, the black hole thermodynamics can be calculated successfully on the apparent horizon. When a relativistic perturbation is applied to the apparent horizon, a similar calculation can also lead to a purely thermal spectrum. The first law of thermodynamics can also be derived successfully at the new supersurface near the apparent horizon. When the event horizon is thought of as a deviation from the apparent horizon, the expressions of the characteristic position and temperature are consistent with the previous viewpoint which asserts that the thermodynamics should be based on the event horizon. It is concluded that the thermodynamics should be constructed exactly on the apparent horizon while the event horizon thermodynamics is just one of the perturbations near the apparent horizon.

关键词： black hole physics -- relativity -- kinematics and dynamics

DFT study of the conductance of molecular wire:The effect of coupling geometry and intermolecular interaction on the transport properties

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Science china Chemistry 2006年第6期49卷 492-498页

作者： QI Yuanhua1,2, GUAN Daren1 & liu Chengbu1 1. institute of theoretical Chemistry, Shandong university, Jinan 250100, china 2. School of physics and Microelectronics, Shandong university, Jinan 250061, china 1. institute of theoretical Chemistry Shandong University Jinan 250100 China 2. School of physics and Microelectronics Shandong University Jinan 250061 China

The density functional theory (DFT) combining with the non-equilibrium Green functions (NEGF) method is applied to the study of the electronic transport properties for a Di-thiol-benzene (DTB) molecule coupled to two Au(111) surfaces. The dependence of the transport properties on the bias, the coupling geometry of the molecule-electrode interface, and the intermolecular interaction are examined in detail. The results show that the existence of the hydrogen atom at the end of the DTB molecule would significantly decrease the transmission coefficients, and then the differential conductance (dI/dV). By changing the position of the DTB molecule located between two electrodes a maximum value of calculated current is observed. It is also found that the intermolecular interaction will strongly influence the transport properties of the system studied.

关键词： non-equilibrium Green functions method, transmission spectrum, the molecular projected selfconsistent Hamiltonian, projected density of state.

theoretical study of the electronic structures and spectroscopic properties of [(4'-XC≡Ctrpy)PtCl]^+ (trpy=2,2':6',2"-terpyridine;X=H,Me and Ph)

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Science china Chemistry 2009年第12期52卷 2226-2236页

作者： WANG Xin,BAI FuQuan,ZHOU Xin,liu Tao & ZHANG HongXing State Key Laboratory of theoretical and Computational Chemistry,institute of theoretical Chemistry,Jilin university,Changchun 130023,china 1. State Key Laboratory of theoretical and Computational Chemistry Institute of Theoretical Chemistry Jilin University Changchun 130023 China

The electronic structures and spectroscopic properties of [(4'-XC≡Ctrpy)PtCl]+(trpy = 2,2':6',2″-terpyridine; X = H (1),methyl (Me) (2),and phenyl (Ph) (3) were studied by the ab initio method. The structures at the ground and excited state were optimized at the B3LYP and CIS levels,respectively. The absorption and emission spectra in the dichloromethane solution were obtained by using the TD-DFT (B3LYP) method associated with the PCM model. The molecular orbital energy of the HOMOs of 1-3 with the d(Pt),p(Cl),π(trpy),and π(XC≡C) character is sensitive to the substituents on the acetylide ligand,but that of the trpy-based LUMOs with the π*(trpy) character varies slightly. The lowest lying emission at 503 nm for 1 is mainly attributed to the 3ILCT perturbed by the 3MLCT and 3LLCT transitions,but that at 535 nm for 2,and that at 558 nm for 3 are mainly attributed to the 3LLCT perturbed by the 3ILCT and 3MLCT transitions. The different electron-donating ability of H,Me,and Ph is responsible for the differences in emission character. Moreover,the calculation results show that the phosphorescent color can be turned by adjusting the substituents. Both the lowest energy absorption and emission of 1―3 are red-shifted in the order of 1<2<3,consistent with the electron-donating of H

关键词： platinum(Ⅱ) complexes TD-DFT absorption spectra charge transfer luminescence

Controllable optical superregular breathers in the femtosecond regime

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Chinese physics B 2018年第1期27卷 307-313页

作者：任杨杨战营刘冲杨文力 School of physics Northwest University Shaanxi Key Laboratory for theoretical physics Frontiers institute of Modern physics Northwest University

We investigate optical superregular breathers in the femtosecond regime under dispersion management in an inho- mogeneous fiber governed by the nonautonomous higher-order nonlinear Schr6dinger equation （NLSE）. Exact solutions describing the dynamics of superregular breathers are obtained. Furthermore, we discuss the propagation behaviors of controllable superregular breathers, including stabilization and recurrence in an exponential dispersion fiber and a peri- odic distributed fiber system. Particularly, the nonlinear dynamics of superregular modes evolved from an identical initial small-amplitude modulation is analyzed in detail.

关键词： nonlinear wave superregular breather controllable dynamics modulation instability

theoretical Study of CH_3CH=CH_2+O(~1D) Reaction: Mechanism and Kinetics

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Chemical Research in Chinese Universities 2012年第1期28卷 147-152页

作者： WU Nan-nan, liu Hong-xia, DUAN Xue-mei and liu Jing-yao State Key Laboratory of theoretical and Computational Chemistry, institute of theoretical Chemistry, Jilin university, Changchun 130021, P. R. china institute of theoretical Chemistry Jilin University State Key Laboratory of Theoretical and Computational Chemistry Changchun 130021

The mechanism and kinetics for the reaction of propene（CH3CH=CH2） molecule with O（1D） atom were investigated theoretically. The electronic structure information of the potential energy surface（PES） was obtained at the B3LYP/6-311＋G（d,p） level, and the single-point energies were refined by the multi-level MCG3-MPWB method. The calculated results show that O（1D） atom can attack CH3CH=CH2 via the barrierless insertion mechanism to form four energy-riched intermediates CH3C（OH）CH2（IM1）, CH3CHCHOH（IM2）, CH2OHCHCH2（IM3） and cyclo CH2OCHCH3（IM4）, respectively, on the singlet PES. The branching ratios as well as the pressure and temperature dependence of various product channels for this multi-well reaction were predicted by variational transition-state and Rice-Ramsperger-Kassel-Marcus（RRKM） theories. The present results will be useful to gain a deep insight into the reaction mechanism and kinetics of CH3CH=CH2＋O（1D） reaction.

关键词： Propene O(lD) Mechanism Kinetics