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Factors influencing hysteresis characteristics of concrete dam deformation

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Water Science and Engineering 2017年第2期10卷 166-174页

作者： jia-he Zhang jian Wang Li-sha Chai College of Water Conservancy and Hydropower Engineering Hohai University Nanjing 210098 China Lixi Barrage Irrigation Management Office of Guangzhou City Guangzhou 510890 China

Thermal deformation of a concrete dam changes periodically, and its variation lags behind the air temperature variation. The lag, known as the hysteresis time, is generally attributed to the low velocity of heat conduction in concrete, but this explanation is not entirely sufficient. In this paper, analytical solutions of displacement hysteresis time for a cantilever beam and an arch ring are derived. The influence of different factors on the displacement hysteresis time was examined. A finite element model was used to verify the reliability of the theoretical analytical solutions. The following conclusions are reached:(1) the hysteresis time of the mean temperature is longer than that of the linearly distributed temperature difference;(2) the dam type has a large impact on the displacement hysteresis time, and the hysteresis time of the horizontal displacement of an arch dam is longer than that of a gravity dam;(3) the reservoir water temperature variation lags behind of the air temperature variation, which intensifies the differences in the horizontal displacement hysteresis time between the gravity dam and the arch dam;(4) with a decrease in elevation, the horizontal displacement hysteresis time of a gravity dam tends to increase, whereas the horizontal displacement hysteresis time of an arch dam is likely to increase initially, and then decrease; and(5) along the width of the dam, the horizontal displacement hysteresis time of a gravity dam decreases as a whole, while the horizontal displacement hysteresis time of an arch dam is shorter near the center and longer near dam surfaces.

关键词： Concretedam Displacement Hysteresis Temperature Analytical solution

Impact of Media Information on Social Response in Disasters:A Case Study of the Freezing‑Rain and Snowstorm Disasters in Southern China in 2008

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International Journal of Disaster Risk Science 2024年第1期15卷 73-87页

作者： jia he Wenjing Duan Yuxuan Zhou Yun Su College of Geographic Science and Tourism Xinjiang Normal UniversityUrumqi 830054China Xinjiang Laboratory of Lake Environment and Resources in Arid Zone Urumqi 830054China Faculty of Geographical Science Beijing Normal UniversityBeijing 100875China Key Laboratory of Environmental Change and Natural Disaster Ministry of EducationBeijing Normal UniversityBeijing 100875China

Disaster information content is an objective mapping of disaster situations,social response,and public *** response to emergency is an important mechanism for implementing and guaranteeing emergency management of major natural hazard-related *** how disaster information content affects social response to emergencies is helpful for managing risk communication and efficient disaster *** on the 2008 freezing-rain and snowstorm disasters in southern China,this study used Python to extract 7,857 case-related media reports and applied natural language processing for text *** used three typical cases to identify and analyze disaster media report content and the relationship between these reports and the social response to the *** categories of disaster response-such as prewarning and forecasting,announcements by the authorities,and social mobilization-appeared in the disaster information in the media,along with disaster impact information,that is,real-time disaster *** response information and an appropriate amount of disaster impact information played important roles in prewarning,disaster relief,public opinion guidance,and social stability maintenance and can serve important functions in communicating with all stakeholders of emergency management,assisting or influencing emergency departments or individuals in decision making,and eliminating "information islands." Empathy caused the general public to become "disaster responders" through receiving *** and an excess of negative information may have a perverse amplification effect on public opinion and increase the unpredictability of the disaster situation and the risk of social crisis.

关键词： Emergency management Freezing-rain and snowstorm disasters Media reports on disasters Social response to emergencies China

Finding map regions with high density of query keywords

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Frontiers of Information Technology & Electronic Engineering 2017年第10期18卷 1543-1555页

作者： Zhi YU Can WANG jia-jun BU Xia HU Zhe WANG jia-he JIN Alibaba-Zhejiang University Joint Institute of Frontier Technologies Zhejiang Provincial Key Laboratory of Service Robot College of Computer Science and Technology Zhejiang University Hangzhou 310027 China Hangzhou Science and Technology Information Research Institute Hangzhou 310001 China

We consider the problem of finding map regions that best match query keywords. This region search problem can be applied in many practical scenarios such as shopping recommendation, searching for tourist attractions, and collision region detection for wireless sensor networks. While conventional map search retrieves isolate locations in a map, users frequently attempt to find regions of interest instead, e.g., detecting regions having too many wireless sensors to avoid collision, or finding shopping areas featuring various merchandise or tourist attractions of different styles. Finding regions of interest in a map is a non-trivial problem and retrieving regions of arbitrary shapes poses particular challenges. In this paper, we present a novel region search algorithm, dense region search(DRS), and its extensions, to find regions of interest by estimating the density of locations containing the query keywords in the region. Experiments on both synthetic and real-world datasets demonstrate the effectiveness of our algorithm.

关键词： Map search Region search Region recommendation Spatial keyword search Geographic information system Location-based service

Physical properties of γ Doradus pulsating stars and their relationship with long-period δ Scuti variables

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Research in Astronomy and Astrophysics 2019年第1期19卷 1-20页

作者： Sheng-Bang Qian Lin-jia Li jia-jia he jia Zhang Li-Ying Zhu Zhong-Tao Han Yunnan Observatories Chinese Academy of Sciences Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Center for Astronomical Mega-Science Chinese Academy of Sciences University of Chinese Academy of Sciences

We present LAMOST data on 168 γ Doradus(γ Dor) pulsating stars including stellar atmospheric parameters of 137 variables and spectral types for all of the samples. The distributions of period(P), temperature(T), gravitational acceleration(log(g)) and metallicity [Fe/H] are shown. It is found that most γ Dor variables are main-sequence stars with early F spectral types and temperatures from 6880 K to7280 K. They are slightly more metal poor than the Sun with a metallicity range from-0.4 to 0. On the H-R and log g-T diagrams, both the γ Dor and δ Scuti(δ Sct) stars occupy in the same region and some are beyond the borders predicted by current stellar pulsation theories. It is discovered that the physical properties of γ Dor stars are similar to those of long-period δ Sct(P > 0.3 d) stars. The stellar atmospheric parameters are all correlated with the pulsation period for short-period δ Sct variables(P here are no such relations for γ Dor or long-period δ Sct stars. These results reveal that γ Dor and long-period δ Sct are the same group of pulsating stars and they are different from short-period δ Sct variables. Meanwhile, 33γ Dor stars are identified as candidates of binary or multiple systems.

关键词： stars:fundamental parameters stars:oscillations stars:binaries:spectroscopic stars:variables:other

Hybrid cooperative intersection management for connected automated vehicles and pedestrians

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Journal of Intelligent and Connected Vehicles 2023年第2期6卷 91-101页

作者： Pinlong Cai jia he Yikang Li Shanghai Artificial Intelligence Laboratory Shanghai 200232China Beijing Key Laboratory of Traffic Engineering Beijing University of TechnologyBeijing 100124China

Connected Automated Vehicles(CAVs)have drawn much attention in recent *** reliable automatic technologies can help CAVs to follow given trajectories ***,safety and efficiency are hard to be ensured since the interactions between CAVs and pedestrians are complex ***,this study focuses on cooperative intersection management for CAVs and *** avoid the effects of uncertainty about pedestrian behaviors,an indirect way is to use pedestrians’signal lights to guide the movements of pedestrians,and such lights with communication devices can share information with CAVs to make decisions *** time domains,a general conflict-free rule is established depending on the positions of CAVs and *** analysis with coordinate calculation is used to accurately determine the feasible vehicle trajectories and the reasonable periods for signal lights turning *** control strategies for the same conditions are compared in simulation experiments,and their performances are *** demonstrate that the proposed cooperative strategy not only balances the benefits of vehicles and pedestrians but also improves the traffic efficiency at the intersection.

关键词： connected automated vehicle intersection pedestrian crosswalk cooperative management

First-principle study on the optical response of phosphorene

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Frontiers of physics 2015年第4期10卷 73-81页

作者： jia-he Lin Hong Zhang Xin-Lu Cheng College of Physical Science and Technology Sichuan University Chengdu 610065 China Key Laboratory of High Energy Density Physics and Technology of Ministry of Education Sichuan University Chengdu 610065 China

The optical response of phosphorene nanostructures was studied using time-dependent density func- tional theory （TDDFT）. Compared with the absorption spectrum of graphene, that of the phospho- rene nanostructure exhibits high absorbance in the ultraviolet region, which indicates a high light absorptivity. In a low-energy resonance zone, a spectral band extends to the entire near-infrared re- gions. When the impulse excitation polarizes in the armchair-edge direction, the low-energy plaslnon in a few-layer phosphorene nanostructure shows an apparent long-range charge-transfer excitation but is significantly less pronounced along the zigzag-edge direction. The edge configuration signifi- cantly affects the absorption spectrum of monolayer phosphorene nanostructures. The armchair-edge and the zigzag-edge serve different functions in the absorption spectrum. Moreover, the absorption spectrum of the few-layer phosphorene nanostructure changes with the number of layers when the impulse excitation polarizes in the armchair-edge direction. In addition, the change in tile low-energy resonance zone is significantly different from that in the high-energy resonance zone.

关键词： phosphorene nanostructures

Preparation and characterization of sulfonated chitosan-modified gold nanoparticles and their surface electronic payload of charged drugs

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Science China(Life Sciences) 2018年第4期61卷 457-463页

作者： Huaisong Wang jia he Ya Ding Xinghua Xia Key Laboratory of Drug Quality Control and Pharmacovigilance China Pharmaceutical UniversityMinistry of Education State Key Laboratory of Analytical Chemistry for Life Science School of Chemistry and Chemical EngineeringNanjing University

Chitosan(CS), a kind of naturally produced polysaccharide with extraordinary biocompatibility and biodegradation, shows much potential to act as reducing and stabilizing agent in the synthesis of gold nanoparticles(AuNPs) for drug delivery. To solve the poor solubility and expand the pharmaceutical applications of CS, various CS derivatives through rational design have been developed and further used to prepare, stabilize, and mediate self-assembling of gold materials. herein, we chose sulfonic chitosan as a stabilizing reagent for the synthesis of highly stable AuNPs(AuNP/SCSs) with diameters of about 3 nm. For investigating their surface electronic payload of charged drugs, the negatively charged fluorescence isothiocyanate(FITC) and positively charged Rhodamine B(Rb) were used as models to be modified on the surface of the AuNP/SCSs via a layer-by-layer(Lb L) method. With a basis of the fluorescence resonance energy transfer(FRET) principle, via adjusting the distance between AuNPs and fluorescent molecules by tuning the layers of charged polymers, the regulation of the fluorescence intensity of the fluorescent molecules has been achieved. In addition, the drug loading efficiency was investigated.

关键词： sulfonic chitosan gold nanoparticle layer-by-layer (LbL) self-assembly fluorescent molecule

Effect of Martian atmosphere on aerodynamic performance of supersonic parachute two-body systems

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Chinese Journal of Aeronautics 2022年第4期35卷 45-54页

作者： Xiaopeng XUE he jia Wei RONG Qi WANG Chih-yung WEN School of Aeronautics and Astronautics Central South UniversityChangsha 410083China Beijing Institute of Space Mechanics and Electricity Beijing 100094China Department of Mechanical Engineering The Hong Kong Polytechnic UniversityHong KongChina

Supersonic flows around parachute two-body systems are numerically investigated by solving the compressible Navier-Stokes equations. In the present study, both rigid and flexible parachute models are considered, which comprise a capsule and a canopy. The objective of the present study is to investigate the effects of the Martian atmosphere on the unsteady flows produced by these parachute two-body models and the structural behavior of the flexible canopy. It was found that in the Martian atmosphere, the supersonic rigid parachutes with shorter trailing distances exhibited weaker aerodynamic interactions between the capsule wake and canopy shock, resulting in a smaller pressure distribution on the typical surfaces of the canopy. By contrast, because the flow modes around the flexible parachute in the Martian atmosphere were similar to those of the rigid parachute under the air conditions of the wind tunnel tests, the canopy shape was almost unchanged. When a new canopy material was designed by decreasing the Young’s modulus and damping coefficient, an area oscillation phenomenon was observed in the flexible parachute with a trailing distance of 10 in the Martian atmosphere. Consequently, the Martian atmosphere(low density and pressure) has a significant effect on the aerodynamic performance of the flexible parachute system.

关键词： Canopy flexibility Fluid structure interaction Martian atmosphere Supersonic parachute Unsteady flow

Mechanisms of Acupuncture in Improving Alzheimer's Disease Caused by Mitochondrial Damage

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Chinese Journal of Integrative Medicine 2022年第3期28卷 272-280页

作者： jiaNG Yu-hang he jia-kai LI Ran CheN Ze-hao jia Bao-hui Department of Acupuncture Guang'anmen HospitalChina Academy of Chinese Medical SciencesBeijing(100053)China

Alzheimer's disease(AD)is one of the most common neurodegenerative diseases among the elderly and it accounts for nearly 80%of all *** pathogenesis of AD is complicated and enigmatic thus *** mitochondrial cascade hypothesis assumes that mitochondrial damage may mediate,drive,or contribute to a variety of AD pathologies and may be the main factor in late-onset ***,there are no widely recognized drugs able to attenuate mitochondrial damage in ***,increasing evidence supports the efficacy of acupuncture for improving the mitochondrial structure and protecting mitochondrial functions in *** review reports the mechanisms by which acupuncture regulates mitochondrial dynamics,energy metabolism,calcium homeostasis and *** conclusion,these findings suggest that AD mitochondrial dysfunction represents a reasonable therapeutic target and acupuncture could play a significant role in preventing and treating AD.

关键词： acupuncture Alzheimer's disease mitochondrial damage review