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geometry of time-dependent PT-symmetric quantum mechanics

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Chinese Physics B 2021年第10期30卷 47-55页

作者：张大剑王清海龚江滨 Department of Physics Shandong UniversityJinan 250100China Department of Physics National University of Singapore117551Singapore

A new type of quantum theory known as time-dependent𝒫PT-symmetric quantum mechanics has received much attention recently.It has a conceptually intriguing feature of equipping the Hilbert space of a𝒫PT-symmetric system with a time-varying inner product.In this work,we explore the geometry of time-dependent𝒫𝒯PT-symmetric quantum mechanics.We find that a geometric phase can emerge naturally from the cyclic evolution of a PT-symmetric system,and further formulate a series of related differential-geometry concepts,including connection,curvature,parallel transport,metric tensor,and quantum geometric tensor.These findings constitute a useful,perhaps indispensible,tool to investigate geometric properties of𝒫PT-symmetric systems with time-varying system’s parameters.To exemplify the application of our findings,we show that the unconventional geometric phase[Phys.Rev.Lett.91187902(2003)],which is the sum of a geometric phase and a dynamical phase proportional to the geometric phase,can be expressed as a single geometric phase unveiled in this work.

关键词： time-dependent𝒫PT-symmetric quantum mechanics geometry time-varying inner product unconventional geometric phase

geometry effect on water-evaporation-induced voltage in porous carbon black film

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Science China(Technological Sciences) 2021年第3期64卷 629-634页

作者： ZHANG ShiYu FANG SunMiao LI LuXian GUO WanLin State Key Laboratory of Mechanics and Control of Mechanical Structures Key Laboratory of Intelligent Nano Materials and Devices of the Ministry of EducationInstitute of Nano ScienceNanjing University of Aeronautics and AstronauticsNanjing 210016China

Water-evaporation-induced electricity generation shows great application prospect due to the volt-level voltage induced by natural water evaporation in ambient environment.Increasing investigations have been conducted on water-evaporation-induced electricity in different materials,surface treatments,working mechanisms and wide ranges of practical applications.However,to further enhance the electricity output remains a great challenge.In this study,we fabricated porous carbon black films with isosceles trapezoid shapes to generate water-evaporation-induced electricity,in contrast with the widely used rectangle samples.We found that an isosceles trapezoid film produces two different voltages by inversing the film,because of different flow rates and capillary heights after inversion.The ratio of these voltages varies with the length of longer base when lengths of shorter base and heights are fixed,and the maximum ratio can reach 1.77:1 in our study.This work shows the importance of geometry design in improving the output voltage.

关键词： water-evaporation-induced voltage porous carbon black film geometry hydrovoltaic technology

geometry-based non-line-of-sight error mitigation and localization in wireless communications

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Science China(Information Sciences) 2019年第10期62卷 149-163页

作者： Jingyu HUA Yejia YIN Anding WANG Yu ZHANG Weidang LU School of Information and Electronic Engineering Zhejiang Gongshang University Zhejiang Provincial Key Laboratory of Information Processing Communication and Networking College of Information Engineering Zhejiang University of Technology

Recently, positioning services have received considerable attention. The primary source of the positioning error is non-line-of-sight(NLOS) propagation. To address this problem, we propose a novel NLOS mitigation scheme, in which the geometric relationship between a base station and a mobile station is used.This makes it possible to identify range measurements corrupted by NLOS errors, and the mobile station can then estimate its position through line-of-sight(LOS) measurements. Moreover, the threshold of the NLOS detector is derived via a hybrid method using both the analytical derivation and computer simulation, which significantly reduces the difficulty of identifying thresholds. After identifying the NLOS measurements, a two-step weighted-least-squares algorithm is used to obtain the localization, in which both range and angle measurements are considered. The simulation results reveal that the proposed algorithm yields a high identification probability of NLOS measurements, which results in improved localization performance.

关键词： wireless localization non-line-of-sight error geometry cellular network residual

Three-dimensional geometry and Kinematics of the Changning Anticline in the Southern Sichuan Basin

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Acta Geologica Sinica(English Edition) 2022年第4期96卷 1432-1450页

作者： YANG Jinhe HE Dengfa ZHANG Weikang HUANG Hanyu Chinese University of Geosciences Beijing School of Energy ResourcesBeijing 100083China

In this study,we aim to clarify the structural characteristics and deformation process of the Changning anticline.We carefully interpret 38 two-dimensional(2D)seismic profiles in the study area and establish three-dimensional(3D)geometric and quantitative kinematic models of the Changning anticline.This study shows that the basement fault controls the formation of the Changning anticline.The fault slope of the main fault in the basement shows’steep in the upper and gentle in the lower’structural characteristics vertically,possessing obvious segmentary characteristics transversely and presents the overall characteristics of’steep in the east and gentle in the west’.Further analysis shows that the Changning anticline proceeds west and terminates at the boundary defined by current surface features but gradually disappears westward across the Mt.Huaying fault zone.Furthermore,we identified that deformation of the Changning anticline began during the early Yanshanian movement period.Under compressional stress from the southeast,the anticline slid forward along the basement fault until the end of the Yanshanian movement period,when the dominant WNW-ESE structure gradually emerged.Since the Himalayan movement period,a series of NE-trending structures have been formed in the anticline,owing to multi-directional compressive stress.

关键词： geometry segmented feature kinematics formation mechanism Changning anticline

The Effects of the geometry of a Current Collector with an Equal Open Ratio on Output Power of a Direct Methanol Fuel Cell

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Energy Engineering 2024年第5期121卷 1161-1172页

作者： Yingli Zhu Jiachi Xie Mingwei Zhu Jun Zhang Miaomiao Li Tianjin Key Laboratory of Integrated Design and On-line Monitoring for Light Industry&Food Machinery and Equipment School of Mechanical EngineeringTianjin University of Science&TechnologyTianjin300222China Tianjin College University of Science and Technology BeijingTianjin301830China Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology College of Mechanical and Electrical EngineeringNanjing University of Aeronautics and AstronauticsNanjing210016China

The open ratio of a current collector has a great impact on direct methanol fuel cell(DMFC)performance.Although a number of studies have investigated the influence of the open ratio of DMFC current collectors,far too little attention has been given to how geometry(including the shape and feature size of the flow field)affects a current collector with an equal open ratio.In this paper,perforated and parallel current collectors with an equal open ratio of 50%and different feature sizes are designed,and the corresponding experimental results are shown to explain the geometry effects on the output power of the DMFC.The results indicate that the optimal feature sizes are between 2 and 2.5 mm for both perforated and parallel flow field in the current collectors with an equal open ratio of 50%.This means that for passive methanol fuel cells,to achieve the highest output power,the optimal feature size of the flow field in both anode and cathode current collectors is between 2 and 2.5 mm under the operating mode of this experiment.The effects of rib and channel position are also investigated,and the results indicate that the optimum pattern depends on the feature sizes of the flow field.

关键词： Direct methanol fuel cell geometry open ratio current collector position

geometry and kinematics of tugerming structural belt in the east of Kuqa Depression,Tarim Basin

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Petroleum Research 2021年第4期6卷 333-350页

作者： Shaoye Chai Chuanxin Li Xuesong Lu Qingong Zhuo Yanjie Gong School of Energy Resources China University of Geosciences(Beijing)Beijing100083China PetroChina Research Institute of Petroleum Exploration and Development Beijing100083China Key Laboratory of Basin Structure and Hydrocarbon Accumulation CNPCBeijing100083China

Accurate interpretation of clutter seismic reflection is of great significance to make clear the structural geometry and kinematics characteristics.Based on field investigations,boreholes and seismic data,forward modeling is carried out under the trishear model of fault-propagated fold principle,and the activity characteristics of the main faults in the study area are quantitatively analyzed using the balanced restoration technique,which may provide important indication for the potential petroleum exploration and development.The results show that separated by Tuziluoke and Tugerming fault,the structural style of the study area can be divided into the deeply buried forelimb,the kink band and the tiny anticline backlimb section.The Tuziluoke fault has been active with strong intensity since the sedimentary period of the Kuqa Formation and,which controls the formation of the growth strata in the deep buried forelimb of the Tuziluoke anticline.The Tugerming fault has been active intermittently since the end of the Jurassic,causing the strata denudation of the Late Jurassic to Paleogene in varying degrees and the development of series of regulating faults.The multi-stage tectonic activities caused the structural high of the anticline migrated from east to west.

关键词： Fault related fold Trishear geometry Kinematics Balanced restoration Kuqa depression

geometry and tectonic deformation of the seismogenic structure for the 8 August 2017 M_S 7.0 Jiuzhaigou earthquake sequence,northern Sichuan, China

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Earth and Planetary Physics 2019年第3期3卷 253-267页

作者： Feng Long GuiXi Yi SiWei Wang YuPing Qi Min Zhao Sichuan Earthquake Agency Sichuan Seistech Corporation Ltd.

To reveal the geometry of the seismogenic structure of the Aug. 8, 2017 M_S 7.0 Jiuzhaigou earthquake in northern Sichuan,data from the regional seismic network from the time of the main event to Oct. 31, 2017 were used to relocate the earthquake sequence by the tomoDD program, and the focal mechanism solutions and centroid depths of the M_L ≥ 3.5 events in the sequence were determined using the CAP waveform inversion method. Further, the segmental tectonic deformation characteristics of the seismogenic faults were analyzed preliminarily by using strain rosettes and areal strains(As). The results indicate:(1) The relocated M_S 7.0 Jiuzhaigou earthquake sequence displays a narrow ～ 38 km long NNW-SSE-trending zone between the NW-striking Tazang Fault and the nearly NSstriking Minjiang Fault, two branches of the East Kunlun Fault Zone. The spatial distribution of the sequence is narrow and deep for the southern segment, and relatively wide and shallow for the northern segment. The initial rupture depth of the mainshock is 12.5 km, the dominant depth range of the aftershock sequence is between 0 and 10 km with an average depth of 6.7 km. The mainshock epicenter is located in the middle of the aftershock region, showing a bilateral rupture behavior. The centroid depths of 32 M_L ≥ 3.5 events range from 3 to 12 km with a mean of about 7.3 km, consistent with the predominant focal depth of the whole sequence.(2) The geometric structure of the seismogenic fault on the southern section of the aftershock area(south of the mainshock) is relatively simple, with overall strike of ～150° and dip angle ～75°, but the dip angle and dip-orientation exhibit some variation along the segment. The seismogenic structure on the northern segment is more complicated; several faults, including the Minjiang Fault, may be responsible for the aftershock activities. The overall strike of this section is ～159° and dip angle is ～59°, illustrating a certain clockwise rotation and a smaller dip angle than the southern segment. The differences betw

关键词： MS 7.0 Jiuzhaigou earthquake sequence relocation focal mechanism seismogenic structure geometry tectonic deformation

Preface of the Special Issue on Symplectic geometry and Mathematical Physics

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Acta Mathematica Sinica,English Series 2024年第1期40卷 1-2页

作者： Huijun Fan Xiaobo Liu Gang Tian Peking University BeijingChina

Symplectic geometry is a branch of differential geometry and differential topology and has its origins in the Hamiltonian formulation of classical mechanics.In the last few decades,symplectic geometry has experienced enormous progress and has had interactions with many other branches of mathematics,including enumerative geometry,low-dimensional topology,mathematical physics,Hamiltonian dynamics,integrable systems etc..

关键词： geometry topology Hamiltonian

On the role of geometry in geo-localization

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Computational Visual Media 2021年第1期7卷 103-113页

作者： Moti Kadosh Yael Moses Ariel Shamir Department of Electrical Engineering Tel-Aviv UniversityTel-AvivIsrael The Efi Arazi School of Computer Science The Interdisciplinary Center HerzliyaHerzliyaIsrael

Consider the geo-localization task of finding the pose of a camera in a large 3 D scene from a single image.Most existing CNN-based methods use as input textured images.We aim to experimentally explore whether texture and correlation between nearby images are necessary in a CNN-based solution for the geo-localization task.To do so,we consider lean images,textureless projections of a simple 3 D model of a city.They only contain information related to the geometry of the scene viewed(edges,faces,and relative depth).The main contributions of this paper are:(i)to demonstrate the ability of CNNs to recover camera pose using lean images;and(ii)to provide insight into the role of geometry in the CNN learning process.

关键词： geo-localization geometry CNN-based solutions synthetic lean images