检索结果-南通市图书馆

A Special Kind of Interplanetary Coronal Mass Ejection

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2024年第12期24卷 185-193页

作者： h.Q.Feng Y.zhao G.Q.zhao h.B.Li L.Xiang J.M.Wang Institute of Space Physics Luoyang Normal University henan Key Laboratory of Electromagnetic Transformation and detection Luoyang Normal University

It is generally believed that coronal mass ejections(CMEs) have magnetic flux rope structures because of their helical shapes. however, only about 30%–40% of interplanetary CMEs(ICMEs) have a local magnetic flux rope structure. The usual explanations are that the spacecraft only crossed the flank of the ropes and failed to detect the complete magnetic flux rope structure or that some processes destroyed these magnetic flux rope structures. Several studies suggest that some ICMEs inherently possess disordered magnetic fields and consequently exhibit no magnetic flux-rope structures. We introduce a special kind of ICME which has a low magnetic field magnitude and stable magnetic field direction, relatively fast expansion speed, and lower proton temperature and density. All three of the measured magnetic field components are relatively stable. We want to know whether these ICMEs also have magnetic flux rope structures or not. We identified 20 special ICMEs and analyzed their evolution based on their observed characteristics. We took a special ICME as an example, which had an apparent rope configuration at 1 au but evolved to a special ICME at 5.4 au, to illustrate that this kind of ICME could come from magnetic clouds(MCs) whose rope structure had been being stretched due to expansion. We inferred that the missing obvious flux rope structure may be due to the expansion of MCs, not the flank crossing effect. however, more than 50% of the events were associated with the dominant x-component of the magnetic field, which indicates a leg ***, the detection of part of these special ICMEs may also be the result of the leg-crossing effect.

关键词： (Sun:) solar wind interplanetary medium Sun: coronal mass ejections (CMEs)

Optimal deployment of Mobile Sensors for Target Tracking in 2d and 3d Spaces

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

IEEE/CAA Journal of Automatica Sinica 2014年第1期1卷 24-30页

作者： Shiyu zhao Ben M Chen Tong h Lee the Graduate School for Integrative Sciences and Engineering National University of Singapore the department of Electrica and Computer Engineering National University of Singapore

This paper proposes a control strategy to autonomously deploy optimal placements of range-only mobile sensors in 2d and 3d spaces. Based on artificial potential approaches, the control strategy is designed to minimize the intersensor and external potentials. The inter-sensor potential is the objective function for optimal sensor placements. A placement is optimal when the inter-sensor potential is minimized. The external potential is introduced to fulfill constraints on sensor trajectories. Since artificial potential approaches can handle various issues such as obstacle avoidance and collision avoidance among sensors, the proposed control strategy provides a flexible solution to practical autonomous optimal sensor deployment. The control strategy is applied to several optimal sensor deployment problems in 2d and 3d spaces. Simulation results illustrate how the proposed control strategy can improve target tracking performance.

关键词： Optimal sensor placement mobile sensor net-work artificial potential target tracking

how do molecular interactions affect fluorescence behavior of AIEgens in solution and aggregate states?

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 Chemistry 2022年第1期65卷 135-144页

作者： Ying Yu hao Xing Zhicong Zhou Junkai Liu herman h-YSung Ian d.Williams Jonathan E.halpert Zheng zhao Ben Zhong Tang department of Chemistry the Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and ReconstructionDepartment of Chemical and Biomedical EngineeringInstitute for Advanced Studyand Guangdong-Hong Kong-Macao Joint Laboratory of Optoelectronic and Magnetic Functional MaterialsThe Hong Kong University of Science and TechnologyClear Water BayKowloonHong KongChina Shenzhen Institute of Molecular Aggregate Science and Engineering School of Science and EngineeringChinese University of Hong KongShenzhenGuangdong518172China department of chemistry The Hong Kong University of Science and TechnologyClear Water BayKowloonHong KongChina AIE Institute Guangzhou Development DistrictHuangpuGuangzhou 510530China

Molecular interactions are crucial in diverse fields of protein folding,material science,nanotechnology,and life *** mounting experimental research controls luminescent behavior by adjusting molecular interactions in light-emitting materials,it remains elusive to correlate microscopic molecular interactions with macroscopic luminescent behavior ***,we synthesized three red luminogens with subtle structural variation and investigated the influence of molecular interactions on their luminescent behavior in solution and aggregate *** results indicate that strongπ-πand d-A interactions in both dilute solution(between luminogen and solvent molecules)and aggregate(between luminogens)states cause the redshift in emission,while weak interactions(e.g.,Van der Waals,C–h…π,and C–h…F interactions)enhance the quantum *** work provides a thoughtful investigation into the complicated influence of various molecular interactions on luminescent behavior.

关键词： molecular interactions fluorescence behaviors AIEgens aggregates

同方期刊数据库

Correlation between microstructure and mechanical properties of columnar crystals in the directionally solidified Mg-Gd-Y-Er alloy

在线全文

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2022年第3期10卷 806-818页

作者： d.R.Fang S.S.zhao X.P.Lin T.Chai Y.Kuo h.Sun Y.dong School of Materials Science and Engineering Northeastern UniversityNo.11Alley 3Wenhua RoadHeping DistrictShenyangChina School of Resources and Materials Northeastern University at QinhuangdaoQinhuangdao 066004China

The Mg-4.58Gd-0.45Y-0.01 Er alloys with different volume fractions of columnar crystals in hard orientation(orientation factor ofbasal plane slip system is less than 0.2)were prepared by changing the pulling rate to regulate the crystal growth *** tests were performed on the Mg-4.58Gd-0.45Y-0.01 Er alloy at room temperature,and the structure after deformation was investigated by electron backscatter diffraction(EBSd).Subsequently,the strengthening mechanism of columnar crystals in hard orientation was *** results show if orientation factors ofbasal plane slip system of columnar crystals are all greater than 0.4(soft orientation),the alloy has low yield strength σ_(s)(64 MPa),but great work hardening ability,and ultimate tensile strength σ_(b) and elongationδare 114 MPa and 37.3%,*** orientation factors ofbasal plane slip system of columnar crystals are all less than 0.2(hard orientation),the alloy has high strength(σ_(s),125 MPa),but poor plasticity(δ,6.32%).If the"hard orientation"and the"soft orientation"columnar crystals are arranged alternately along the direction perpendicular to the crystal growth,the alloy has both superior strength(σ_(s),102 MPa)and excellent plasticity(δ,22.5%)at room *** improved comprehensive mechanical property can be attributed to two *** the one hand,the"hard orientation"columnar crystals can prevent the"soft orientation"crystals deforming,so the strength is *** the other hand,the"hard orientation"columnar crystals themselves can withstand a certain amount of deformation to retain appropriate plasticity.

关键词： directional solidification Mg-Gd-Y-Er alloy hard orientation Mechanical prop

Studies of the dissociation and the protonation of TB-chlorosulphophenol

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 1997年第1期15卷 68-75页

作者： Zhu, CZ Yang, BL zhao, h Gu, WX Ai, SY department of Chemistry East China Normal University Shanghai 200062 China [*]department of Chemistry East China Normal University Shanghai 200062 China

The dissociation constant of each step for TB-chlorosulphophenol has been determined by potentiometric method, and the thermodynamic constants, delta G degrees, delta h degrees and delta S degrees, of the dissociation process have been calculated. The protonation constants were measured by the spectrophotometric method. The ph values of various forms of anions of the chromogenic reagent at their concentrations were also calculated.

关键词： dissociation protonation TB-chlorosulphophenol

Empirical models for predicting lateral spreading considering the effect of regional seismicity

在线全文

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2012年第1期11卷 121-131页

作者： Zhang Jian Yang Changwei John X. zhao Graeme h. Mcgerry department of Civil Engineering Southwest Jiaotong University Chengdu 610031 China GNS Science Lower Hutt New Zealand

A revised empirical model has been developed for predicting liquefaction-induced lateral spreading displacement （Ld） as a function of both response spectral acceleration derived from strong-motion attenuation models and geotechnical parameters from Youd＇s Ld data set （Youd website）. This revised model is different from the model of Zhang and zhao, which overcame some drawbacks of earlier models for predicting lateral spreading and was primarily used in Japan and the western U.S. The revised model can potentially be applied anywhere if ground shaking （in terms of 5% damped acceleration or displacement response spectra） can be estimated using local strong-motion attenuation relationships. The revised model is examined using data from Japan and the western U.S. and applied to Turkey and New Zealand, where the ground shaking is estimated using appropriate strong-motion attenuation relationships for each region. The accuracy of the revised model is evaluated by comparing its predicted lateral displacements with those measured in actual earthquakes. The results show that the revised model can account for the effects of local seismicity on lateral spreading displacements and is comparable with existing prediction models.

关键词： lateral spreading liquefaction strong-motion attenuation

The W-11-4A Platform Comprehensive Strength Monitoring System

在线全文

学校读者我要写书评

暂无评论

China Ocean Engineering 1998年第2期13卷 135-146页

作者： Shen, Zh Li, h Xue, YI Chen, JC zhao, Q Chinese Acad Sci Inst Mech Beijing 100080 Peoples R China Louisiana Tech Univ Appl & Computat Anal & Modeling Program Ruston LA 71272 USA Acad Sinica S China Sea Inst Oceanol Guangzhou 510301 Peoples R China

A comprehensive strength monitoring system used on a fixed jacket platform is presented in this paper. The long-term monitoring of W-11-4A platform achieved. Structural responses (strain and acceleration) at selected locations, as well as associated environmental parameters, have been obtained. The emphasis of the paper is placed on the system design, and the instrumentation and operation methodology employed in the monitoring of the structural responses. The performance of the system and the characteristic results obtained during its 13-month operation are also summarized.

关键词： monitoring techniques comprehensive strength monitoring structural responses waterproof strain transducers underwater instrumentation techniques

Optimization Study of the Efficient Spindle

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2008年第3期17卷 243-246页

作者： Y.d.Kim d.h.Chun M.S.Kang h.d.Kim Korea Textile Machinery Research Institute School of Textiles Yeungnam University School of Mechanical Engineering Andong National University

In the field of yarn dyeing, the most generally employed method is a type of package dyeing which uses a package of cheese stacked on a spindle made of a perforated tube. Spindles up to now, have been designed without considering the characteristics of dyeing liquid, focusing only on the geometric configuration which cause many problems such as lack of level dyeing. To improve the level dyeing and find the appropriate spindle configuration for the most effective dyeing process, this study examines the spindle flow-field in detail, using a computational method. Flow characteristics inside the spindle have been investigated with varying in porosity, porous diameter and the velocity of the flow. The results show that the total pressure of the flow through the spindle is used to overcome body force. The characteristics of the flow from the porous spindle could also be observed. Based on the results from this study, an effective spindle configuration for level-dyeing has been proposed.

关键词： Porosity Spindle Yarn dyeing Computational Fluid dynamics

Chloride content and ph value in the pore solution of concrete under carbonation

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2013年第1期14卷 71-78页

作者： Xiao-mei WAN Folker h. WITTMANN Tie-jun zhao hong FAN Aedificat Institute Freiburg Freiburg D-79100 Germany School of Civil Engineering Qingdao Technological University

Chloride content and the ph value of the pore solution in the neighborhood of steel reinforcement are decisive pa- rameters for initiation and rate of corrosion. The pore solution of cement mortar and hardened cement paste has been expressed from the pore space by high pressure in the investigation. The influence of the water-cement ratio, age, and addition of chloride to the fresh mix on chloride content in the pore solution has been determined by ion chromatography. At the same time the ph value of the pore solution has been determined. The dissolved chloride content decreases with increase in the water-cement ratio. The amount of bound chloride increases with time, but it decreases with decreasing content of dissolved chloride in the pore solution. A significant influence of carbonation on the dissolved chloride content of the pore solution has been observed. With complete carbonation, the dissolved chloride content in cement mortar and hardened cement paste increases by a factor between 2 and 12. The bound chloride decreases by 27%--54%. As expected, the ph value decreases from around 13.2 to as low as 8.0 due to car- bonation. It can be concluded that carbonation not only lowers the ph value but liberates bound chloride. This is one obvious reason why the combined action of chloride penetration and carbonation accelerates steel corrosion and shortens the service life of reinforced concrete structures.

关键词： Chloride Pore solution Carbonation ph value