检索结果-南通市图书馆

Binding Energy of Biexcitons in Two-Dimensional Semiconductors

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 1998年第8期15卷 588-590页

作者： LIU Jian-jun KONG xiao-jun WEI cheng-wen LI shu-shen National Laboratory for Superlattices and Microstructures Beijing 100083 Department of Physics Hebei Normal UniversityShijiazhuang 050016

The binding energies of a two-dimensional(2D)biexciton have been calculated variationally for all values of the effective electron-to-hole mass ratio u by using a three-parameter wave *** ratio of the binding energy of a 2D biexciton to that of a 2D exciton is found to be from 0.582 to *** results agree fairly well with previous experimental *** results of this approach are compared with those of earlier theories.

关键词： function. variational parameter

Experimental and numerical investigation on the gas leakage regime for ventilated tail cavity of an underwater vehicle

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2023年第1期35卷 46-60页

作者： xiao-bo Quan Shao-hua cheng College of Shipbuilding Engineering Harbin Engineering UniversityHarbin150001China China Academy of Launch Vehicle Technology Beijing100076China Beijing Institute of Astronautical Systems Engineering Beijing100076China

The objective of this paper is mainly to investigate the ventilated tail cavity flow of an underwater vehicle with focus on the gas leakage regime by experimental and numerical methods.A high-speed camera and pressure measurement system are used to record the cavity flow patterns and pressure behavior,*** numerical simulation is carried out with volume of fluid(VOF)model and Filter-based turbulence model(FBM).Good agreement can be obtained between the experimental and numerical *** are three gas leakage types in the evolution of the intact tail cavity,i.e.,twin-vortex tube entrainment(TVTE),toroidal vortex shedding(TVS)and hybrid twin-vortex tube entrainment and toroidal vortex shedding(TVTE-TVS).With the increase of Fr,the unsteady behavior of the cavity with different gas leakage types becomes more *** internal flow characteristics revealed three distinct regions including the ventilation influence region,the reverse flow region and the high shear flow region and have an important effect on the transition of gas leakage regime.

关键词： Ventilated tail cavity gas leakage regime unsteady behavior internal flow characteristics

Weak Merging Scenario of CLASH Cluster A209

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2024年第4期24卷 174-182页

作者： Wen-cheng Feng Heng Yu Hai-Hui Zhao xiao-Lan Hou shu-Mei Jia cheng-Kui Li Yu-Lin cheng Paolo Tozzi Ming Sun Yong Chen Department of Physics and Institute of Theoretical Physics Nanjing Normal UniversityNanjing 210023China Key Laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China Department of Astronomy Beijing Normal UniversityBeijing 100875China Department of Astronomy Yunnan UniversityKunming 650091China INAF—Osservatorio Astrofisico di Arcetri Largo E.Fermi50122 FirenzeItaly Department of Astronomy University of VirginiaP.O.Box 400325CharlottesvilleVA 22904-4325USA

We study the structural and dynamical properties of A209 based on Chandra and XMM-Newton *** obtain detailed temperature,pressure,and entropy maps with the contour binning method,and find a hot region in the NW *** X-ray brightness residual map and corresponding temperature profiles reveal a possible shock front in the NW direction and a cold front feature in the SE *** with the galaxy luminosity density map we propose a weak merger scenario.A young sub-cluster passing from the SE to NW direction could explain the optical subpeak,the intracluster medium temperature map,the X-ray surface brightness excess,and the X-ray peak offset together.

关键词： X rays:galaxies:clusters galaxies:clusters:intracluster medium galaxies:clusters:Abell 209

Profile-dynamic based fictitious play

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2021年第6期64卷 230-232页

作者： xiao ZHANG Daizhan cheng School of Control Science and Engineering Shandong University Academy of Mathematics and Systems Science Chinese Academy of Sciences

Dear editor,The fictitious play(FP) was initially proposed by Brown [1]in 1951 as a handy learning rule. The main idea of FP can be described as follows: In a game process, the player who adopts FP assumes that the others choose their strategies randomly and independently, according to a fixed distribution. Based on this assumption, the player tends to choose his or her own strategy empirically to counter the opponents and ultimately earn more benefits. Many distinguished studies have been springing up after the introduction of FP.

关键词： Profile-dynamic based fictitious play profile

An efficient method for identification of risk factors

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2009年第12期52卷 3626-3631页

作者： cheng Jin xiao Rucheng Department of Bridge Engineering Tongji UniversityShanghai 200092China

This paper presents a method to identify risk factors during bridge *** method integrates the concepts of analytical hierarchy process and fuzzy consistent matrix *** advantage of the method is that instead of using 9-point scale of relative importance of the conventional analytical hierarchy process,it uses a 3-point scale to describe the scale of importance,thus greatly simplifying the identification problem of risk ***,the difficulties of making judgment and comparison caused by uncertainty that jeopardizes the accuracy of the results in the conventional analytical hierarchy process can also be *** advantage of the method is that it does not involve consistency checking,thus saving a large amount of CPU *** has been demonstrated with a numerical example that the proposed fuzzy analytical hierarchy process based on 3-point scale can offer significant computational savings over the conventional analytical hierarchy process.

关键词： analytical hierarchy process risk fuzzy consistent matrix identification

Hydrophobic long-chain two-dimensional perovskite scintillators for underwater X-ray imaging

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2024年第1期43卷 175-185页

作者： Jin-xiao Zheng Zi-An Zhou Tiao Feng Hui Li cheng-Hua Sun NüWang Yang Tian Yong Zhao shu-Yun Zhou Key Laboratory of Photochemical Conversion and Optoelectronic Materials Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Laboratory of Bioinspired Smart Interfacial Science and Technology of the Ministry of Education Beijing Key Laboratory of Bioinspired Energy Materials and DevicesSchool of ChemistryBeijing Advanced Innovation Center for Biomedical EngineeringBeihang UniversityBeijing 100191China Department of Engineering Physics Tsinghua University and Key Laboratory of Particle and Radiation Imaging Ministry of EducationTsinghua UniversityBeijing 100084China e-mail:yangt@***

The underwater X-ray imaging technology development is significant to subaqueous target reconnaissance/detection/identification, subfluvial archaeology,submerged resource exploration, etc. As the core of X-ray imaging detection, the scintillator has been plagued by inherent moisture absorption and decomposition, and strict requirements for seamless packaging and ***, we designed a manganese-doped two-dimensional(2D) perovskite scintillator modified by hydrophobic longchain organic amine through the combination of component and doping engineering. The modified perovskites show high water repellency that can be used as an underwater X-ray scintillator. X-ray images of aquatic organisms or other objects with a high spatial resolution of10 lp·mm^(-1) at a big view field(32 mm × 32 mm) were obtained by scintillation screen. This hydrophobic perovskite scintillator based on molecular design is of great promise in underwater X-ray nondestructive testing technology development.

关键词： Two-dimensional perovskite Hydrophobic Scintillators Underwater X-ray imaging Underwater nondestructive testing technology

The PQCD approach towards to next-to-leading order:A short review

在线全文

学校读者我要写书评

暂无评论

Frontiers of physics 2021年第2期16卷 175-193页

作者： Shan cheng Zhen-Jun xiao School of Physics and Electronics Hunan UniversityChangha 410082 Department of Physics and Institute of Theortical Physics Nangjing Normal UniversityNanjing 210023China

In this short review we elaborate the significance of resummation in kτ factorization theorem,and summarize the recent progresses in the calculations of the next-to-leading order contributions to B meson decays from the perturbative QCD(PQCD)*** also comment on the current sta-tus of the PQCD approach and highlight some key issues to develop it in the near future for more phenomenological applications.

关键词： flavor physics perturbative QCD,kτfactorization next-to-leading order

Heparanase mRNA expression and point mutation in hepatocellular carcinoma

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2004年第19期10卷 2795-2799页

作者： xiao-PengChen Yin-BibLiu JingRui shu-YouPeng cheng-HongPeng Zi-YanZhou Liang-HuiShi Hong-WeiShen BinXu DepartmentofSurgery AffiliatedYijishanHospitalWannanMedicalCollegeWuhu241001AnhuiProvinceChina DepartmentofSurgery SecondAffiliatedHospitalMedicalSchoolofZhejiangUniversityHangzhou310009ZhejiangProvinceChina

AIM: To explore the expression of heparanase mRNA and point mutation in hepatocellular carcinoma (HCC). METHODS: Reverse transcription polymerase chain reaction was used to measure the expression of heparanase mRNA in the primary tumor tissues and surrounding liver tissues of 33 HCC patients. T-A cloning and sequencing were used to detect whether there was any mutation in the amplified PCR products. RESULTS: The expression of heparanase mRNA waspositive in 16 primary tumor tissues of HCC, and the positive rate was 48.5%, which was significantly higher than that in the surrounding liver parenchyma (P<0.01). The positive rate for heparanase gene in high-tendency to metastatic recurrence group (71.4%, 10/14) was obviously higher than that in low-tendency to metastatic recurrence group (31.6%, 6/19) (P= 0.023). The positive rate for heparanase gene in paltients with metastatic recurrence during postoperative follow-up (78.6%, 11/14) was also significantly higher than that in those without metastatic recurrence (21.4%, 3/14) (P = 0.003). Sequence analysis of the HPA PCR products was made in 7 patients, and 2-point mutations were found in 4 patients, one of which was sense mutation, neither base insertion nor deletion was detected. The mutation rate was 57.1% (4/7). CONCLUSION- The expression rate of heparanase mRNA increases in HCC, and HPA mRNA may be one of the reliable markers for the metastatic activity gained by the liver tumor cells and could be used clinically in predicting metastatic recurrence of HCC. Point mutation may be one of the causes for enhanced heparanase mRNA expression.

关键词：肝素酶 mRNA 基因表达基因突变肝细胞癌肿瘤

Tunable circularly-polarized turnstile-junction mode converter for high-power microwave applications

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2018年第6期27卷 502-506页

作者： xiao-Yu Wang Yu-Wei Fan Ting shu cheng-Wei Yuan Qiang Zhang （College of Advanced Interdisciplinary Studies National University of Defense Technology Changsha 410073 China

Frequency tunability has become a subject of concern in the field of high-power microwave（HPM） source ***, little information about the corresponding mode converter is available. A tunable circularly-polarized turnstilejunction mode converter（TCTMC） for high-power microwave applications is presented in this paper. The input coaxial TEM mode is transformed into TE（10） mode with different phase delays in four rectangular waveguides and then converted into a circularly-polarized TE（11） circular waveguide mode. Besides, the rods are added to reduce or even eliminate the reflection. The innovations in this study are as follows. The tunning mechanism is added to the mode converter, which can change the effective length of rectangular waveguide and the distance between the rods installed upstream and the closest edge of the rectangular waveguide, thus improving the conversion efficiency and bandwidth. The conversion efficiency of TCTMC can reach above 98% over the frequency range of 1.42 GHz–2.29 GHz, and the frequency tunning bandwidth is about 47%. Significantly, TCTMC can obtain continuous high conversion efficiency of different frequency points with the change of tuning mechanism.

关键词： mode converter high conversion efficiency frequency tuning performance