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Absorption-Amplification Response with or Without Spontaneously Generated Coherence in a Coherent Four-Level Atomic Medium

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Communications in Theoretical Physics 2004年第3X期42卷 425-430页

作者： LIJia-Hua YANGWen-Xing pengju-cun DepartmentofPhysics HuazhongUniversityofScienceandTechnologyWuhan430074China InstituteofPhysicsandMathematics theChineseAcademyofSciencesWuhan430071China DepartmentofPhysics XiaoganNormalUniversityXiaogan432100China

We discuss and analyze the absorption-amplification properties of a weak probe field in a typical four-level atomic system in the presence of an additional coherence term, the spontaneously generated coherence term. Theinfluences of the spontaneously generated coherence and a coherent pump field on the probe absorption (amplification)are investigated in detail. We show that the absorption of such a weak probe field can be dramatically enhanced dueto the presence of the spontaneously generated coherence. At the same time, the probe-absorption profile exhibitsthe double-peak structure and the probe-absorption peak gradually decreases as the pump intensity increases. On thecontrary, the amplification of such a weak probe field near the line center of the probe transition can be achieved byadjusting the coherent pump field intensity in the absence of the spontaneously generated coherence.

关键词：探针吸收作用量子相干量子干涉量子光学吸收-放大响应

Optical Multi-wave Mixing Process Based on Electromagnetically InducedTransparency

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Communications in Theoretical Physics 2004年第1期41卷 106-110页

作者： LIJia-Hua pengju-cun CHENAi-Xi DepartmentofPhysics HuazhongUniversityofScienceandTechnologyWuhan430074China DepartmentofPhysics XiaoganNormalUniversityXiaogan432100China DepartmentofPhysics HuazhongUniversityofScienceandTechnologyWuhan430074ChinaWuhanInstituteofPhysicsandMathematicstheChineseAcademyofSciencesWuhan430071China

In this paper, we propose and analyze an optical multi-wave mixing scheme for the generation of coherent light in a five-level atomic system in the context of electromagnetically induced transparency. A detailed semiclassical study of the propagation of generated mixing and probe fields is demonstrated. The analytical dependence of the generated mixing field on the probe field and the respective detuning is predicted. Such a nonlinear optical process can be used for generating short-wavelength radiation at low pump intensities.

关键词： optical multi-wave mixing electromagnetically induced transparency Rabi frequency

Absorption-Dispersion Properties in a Four-Level Atomic System with Vacuum-Induced Coherence

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Communications in Theoretical Physics 2005年第1X期44卷 146-150页

作者： WEIHua LIJia-Hua ZHANZhi-Ming pengju-cun DepartmentofPhysics HuazhongUniversityofScienceandTechnologyWuhan430074China StateKeyLaboratoryofLaserTechnology HuazhongUniversityofScienceandTechnologyWuhan430074China DepartmentofPhysics XiaoganNormalUniversityXiaogan432100China

We discuss and analyze absorption-dispersion response for the probe field in a typical four-level atomic system with vacuum-induced coherence (VIC) arising from the cross coupling pathways associated with a pair of upper excited hyperfine levels. We find that VIC effect can preserve electromagnetically induced transparency (EIT) by using the detailed numerical simulations based on the density-matrix equations and analytical calculations in the dressed-state picture. We also show that the atomic hyperfine structure cannot be a hindrance to obtaining EIT.

关键词：真空感应器一致性探测器吸收散射频率散射

Large Enhancement of Probe Amplification with Population Inversion in a Four-Level Atomic System with Vacuum-Induced Coherence

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Communications in Theoretical Physics 2005年第5期43卷 905-909页

作者： LIJia-Hua YANGWen-Xing LUOJin-Ming pengju-cun DepartmentofPhysics，HuazhongUniversityofScienceandTechnology Wuhan430074，China CentreforColdAtomPhysics theChineseAcademyofSciencesWuhan430071，China DepartmentofPhysics XiaoganNormalUniversityXiaogan432100China

In this paper, we discuss and analyze theoretically probeabsorption-amplification response in a four-level coherent atomic system with vacuum-inducedcoherence via changing the sign of the parameter f, with f denoting the ratio of a pair of dipolemoments associated with a doublet of closely upper hypernne sublevels. We find that the amplitude ofthe probe amplification for the case f = -1 can be about one order of magnitude larger than thatachievable for the case f = 1. In addition, with respect to the case f = -1 the probe amplificationcan be maintained all the time with weak incoherent pumping for a wide range of the probe detuning.

关键词： probe absorption-amplification population inversion

Double-Cascade Continuous-Wave Four-Wave Mixing Scheme in a Coherent Cold Atomic Medium

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Communications in Theoretical Physics 2005年第6期43卷 1111-1114页

作者： LIJia-Hua CHENAi-Xi ZHANZhi-Ming pengju-cun DepartmentofPhysics HuazhongUniversityofScienceandTechnologyWuhan430074China CenterforColdAtomPhysics theChineseAcademyofSciencesWuhan430071China StateKeyLaboratoryofLaserTechnology HuazhongUniversityofScienceandTechnologyWuhan430074China DepartmentofPhysics XiaoganNormalUniversityXiaogan432100China

We demonstrate the efficient generation of coherent light in a four-level double-cascade atomic medium by continuous-wave low-intensity laser radiation. We derive the corresponding explicit analytical expressions for the generated four-wave mixing (FWM) field. Dependencies of the intensity of the generate FWM field on the propagation distance, on the input-wave intensity, and on the photon detuning are investigated. To conclude, we also give a brief discussion on the experimental realization of the proposed scheme.

关键词： continuous wave four-wave mixing atomic coherence

Low-cost and fluoride-free synthesis of MFI zeolite nanosheets with enhanced stability for benzene alkylation with ethanol

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Journal of Energy Chemistry 2025年第1期100卷 458-468页

作者： Peng Zhu cun Liu Yiren Yu Guoshu Gao Yumeng Zhao Xiongfu Zhang Guodong Liu Guohui Yang State Key Laboratory of Fine Chemicals School of Chemical Engineering Dalian University of Technology State Key Laboratory of Catalysis Dalian Institute of Chemical Physics Chinese Academy of Sciences

Zeolite nanosheets with a short b-axis thickness are highly desirable in lots of catalytic reactions due to their reduced diffusion resistance. Nevertheless, conventional synthesis methods usually require expensive structure-directing agents(SDAs), pricey raw materials, and eco-unfriendly fluorine-containing additives. Here, we contributed a cost-effective and fluoride-free synthesis method for synthesizing high-quality MFI zeolite nanosheets through a Silicalite-1(Sil-1) seed suspension and urea cooperative strategy, only with inexpensive colloidal silica as the Si source. Our approach was effective for synthesizing both Sil-1 and aluminum-containing ZSM-5 nanosheets. By optimizing key synthesis parameters,including seed aging time, seed quantity, and urea concentration, we achieved precise control over the crystal face aspect ratio and b-axis thickness. We also revealed a non-classical oriented nanosheet growth mechanism, where Sil-1 seeds induced the formation of quasi-ordered precursor particles, and the(010)crystal planes of these particles facilitated urea adsorption, thereby promoting c-axis-oriented *** obtained ZSM-5 nanosheets exhibited exceptional catalytic performance in the benzene alkylation with ethanol, maintaining stability for over 500 h, which is 5 times longer than traditional ZSM-5 catalysts. Furthermore, large-scale production of ZSM-5 nanosheets was successfully carried out in a 3 L highpressure autoclave, yielding samples consistent with those from laboratory-scale synthesis. This work marks a significant step forward in the sustainable and efficient production of MFI nanosheets using inexpensive and environmentally friendly raw materials, offering the broad applicability in catalysis.

关键词： MFI zeolite ZSM-5 Nanosheets Scale-up synthesis Aromatic alkylation

Computer‑aided CT image processing and modeling method for tibia microstructure

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Bio-Design and Manufacturing 2020年第1期3卷 71-82页

作者： pengju Wang Su Wang School of Mechanical Engineering Harbin Institute of TechnologyHarbinChina School of Mechanical Engineering Sichuan UniversityChengduChina

We present a method for computed tomography(CT)image processing and modeling for tibia microstructure,achieved by using computer graphics and fractal *** the large-scale image data of tibia species with DICOM standard for clinical applications,we take advantage of algorithms such as image binarization,hot pixel removing and close operation to obtain visually clear image for tibia *** of these images are based on 20 CT scanning images with 30μm slice thickness and 30μm interval and continuous changes in *** each pore,we determine its profile by using an improved algorithm for edge ***,to calculate its three-dimensional fractal dimension,we measure the circumference perimeter and area of the pores of bone microstructure using a line fitting method based on the least ***,we put forward an algorithm for the pore profiles through ellipse *** results show that the pores have significant fractal characteristics because of the good linear correlation between the perimeter and the area parameters in log–log scale coordinates system,and the ratio of the elliptical short axis to the long axis through ellipse fitting tends to *** on support vector machine and structural risk minimization principle,we put forward a mapping database theory of structure parameters among the pores of CT images and fractal dimension,Poisson’s ratios,porosity and equivalent *** this basis,we put forward a new concept for 3D modeling called precision-measuring digital expressing to reconstruct tibia microstructure for human hard tissue.

关键词： Tibia CT image processing Fractal dimension Support vector machine 3D modeling

Modulating charge separation and transfer kinetics in carbon nanodots for photoredox catalysis

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Journal of Energy Chemistry 2020年第11期29卷 365-377页

作者： pengju Yang Zhidong Yang School of Chemistry and Chemical Engineering Shanxi UniversityTaiyuan 030006ShanxiChina

Artificial photosynthesis has gained increasing interest as a promising solution to the worldwide energy and environmental issues. A crucial requirement for realizing a sustainable system for artificial photosynthesis is to explore low cost, highly-efficient and stable photoactive materials. Carbon nanodots(CNDs) have attracted considerable attention owing to their low cost, tunable chemistry and unique light-harvesting capability. Previous review articles have highlighted the photocatalytic and photoelectrocatalytic applications of CNDs and CNDs-based composite photocatalysts. However, the control of the separation and transfer processes of photogenerated electron/hole pairs in CNDs has not been *** review summarizes the recent progress in the design of CNDs as new light-harvesting materials and highlights their applications in photocatalytic hydrogen production, CO2 photoreduction and environmental remediation. Strategies that have been employed to modulate the separation and transfer kinetics of photogenerated charge carriers in CNDs are discussed in detail. The challenges and new directions in this emerging area of research are also proposed.

关键词： Carbon nanodot Artificial photosynthesis Charge separation Visible light

The Evolution Dynamic and Long-Run Equilibrium in a Stock Market with Heterogeneous Traders

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Journal of Systems Science and Systems Engineering 2020年第1期29卷 55-67页

作者： pengju Zhao Wei Zhang Yumin Liu College of Management and Economics Tianjin UniversityTianjin 300072China System and Industrial Engineering Research Center of Zhongyuan University of Technology Zhengzhou 450007China Business School Zhengzhou universityZhengzhou 450000China

This paper uses ideas from biological evolution to analyze the evolution of the securities market in which rational and irrational traders coexist.A market evolutionary model is developed to describe the dynamic trajectories of rational and irrational traders'*** main question is,are irrational traders eliminated as the securities market *** paper considers the impact of new entrants on the security market long-term *** addition,it discusses the existence and uniqueness of the long-term equilibrium The paper finds that,under some market conditions,irrational traders could survive in the long run.

关键词： Behavioral Finance irrational traders financial evolution theory random dynamic system