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Public health preparedness and responses to the coronavirus disease 2019(COVID-19)pandemic in South Asia:a situation and policy analysis

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Global Health Journal 2020年第4期4卷 121-132页

作者： Amitabha Sarkar Guangqi Liu Yinzi Jin zheng Xie Zhi-Jie zheng Centre of Social Medicine and Community Health School of Social Sciences(Building-II)Jawaharlal Nehru UniversityNew Mehrauli RoadNew Delhi 110067India Department of Global Health School of Public HealthPeking University38 Xueyuan RoadHaidian DistrictBeijing 100191China Institute for Global Health Peking University38 Xueyuan RoadHaidian DistrictBeijing 100191China

Like rest of the world,the South Asian region is facing enormous challenges with the coronavirus disease 2019(COVID-19)*** socio-economic context of the eight South Asian countries is averse to any longterm lockdown program,but the region still observed stringent lockdown close to two *** paper analyzed major measures in public health preparedness and responses in those countries in the *** research was based on a situation analysis to discuss appropriate plan for epidemic preparedness,strategies for prevention and control measures,and adequate response management *** on the data from March 21 to June 26,2020,it appeared lockdown program along with other control measures were not as effective to arrest the exponential growth of fortnightly COVID-19 cases in Afghanistan,Bangladesh,India,Nepal and ***,Bhutan,Maldives and Sri Lanka have been successfully limiting the spread of the *** in-depth analysis of prevention and control measures espoused densely populated context of South Asia needs community-led intervention strategy,such as case containment,in order to reverse the growing trend,and adopt the policy of mitigation instead of suppression to formulate COVID-19 action *** the other hand,mechanism for response management encompassed a four-tier approach of governance to weave community-led local bodies with state,national and international governance actors for enhancing the countries’emergency operation *** is concluded resource-crunch countries in South Asia are unable to cope with the disproportionate demand of capital and skilled health care workforce at the time of the ***,response management needs an approach of governance maximization instead of resource *** epidemiologic management of population coupled with suitable public health prevention and control measures may be a more appropriate strategy to strike a balance between economy and population health during the t

关键词： Coronavirus disease 2019 COVID-19 Pandemic Intervention strategy Epidemiological management Public health South Asia

A Novel Angle of Arrival Tracking Method in Large-Scale-Array Systems

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China Communications 2022年第9期19卷 171-190页

作者： Chen zheng Dekang Liu Xuhui Ding Xiangyuan Bu Zhongshan Zhang School of Information and Electronics Beijing Institute of TechnologyBeijing 100081China

In this paper,we investigate the problem of angle of arrival(AOA)tracking for the largescale array in terahertz(THz)communication,which has a large size and a narrow beam,highly demanding an accurate angle *** the one hand,the system usually adopts a hybrid structure with limited radio-frequency(RF)chains,which increases the difficulty of angle estimation;on the other hand,the rapid mobility of users also brings new challenges to angle *** address the above challenges,a two-stage tracking framework is proposed in this paper,which employs the random phase matrix and orthogonal long pilots in the first stage to reduce the complicated multi-user estimation to multiple single-user estimations,followed by using both wide and narrow beams in the second stage to serve high-speed and low-speed ***,a generalized-approximated-message-passing(GAMP)method is proposed for facilitating a low-accuracy estimation of the angles,followed by adopting a modified expectation-maximization(EM)algorithm based phase estimation to unbiased estimate the instantaneous angle with the help of high-gain characteristics of the *** proposed structure can not only simplify the estimation complexity,but also improve the estimation accuracy due to its capability of transferring the non-linear problem of angle observation into a linear gaussian *** addition,the Kalman tracking framework is employed for performing a continuous angle *** results show that the angle estimation based on the random phase matrix in the initial stage can obtain a high enough estimation accuracy,while the GAMP algorithm implemented in the second stage can quickly capture the angle range under the Rayleigh *** performance of the proposed EM-based tracking method is shown to outperform the traditional extended Kalman filter(EKF)method.

关键词： angle tracking hybrid MIMO communications analog matrix

Microstructure and properties of hydrogenated TB8 alloy

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Rare Metals 2017年第4期36卷 242-246页

作者： Ping Li Bao-Guo Yuan Ke-Min Xue zheng Jiang School of Materials Science and Engineering Hefei Universityof Technology Hefei 230009 China

Thermohydrogen processing can enhance workability, decrease flow stress and deforming tempera- ture of titanium alloys. In this study, thermohydrogen processing was carried out for metastable β-type TB8 alloy. The microstructures of hydrogenated TB8 alloy were investigated based on scanning electron microscopy （SEM）, transmission electronic microscopy （TEM） as well as X-ray diffraction （XRD） analysis. The results reveal that 6 hydride phase forms in the hydrogenated TB8 alloy, but the amount of β phase increases with hydrogen content increasing. Single β phase appears when the hydrogen content reaches 0.7 wt%. The alloying elements redistrib- ute in the hydrogenated TB8 alloy, and hydrogen leads to the reduction of the alloying elements in β phase. The room-temperature compression tests were performed on a MTS809 machine. It is found that the room-temperature yield strength of hydrogenated TB8 alloy decreases. And minimum yield strength is obtained at a hydrogen content of 0.5 wt%. The ductility does not decrease within 0.7 wt% hydrogen content. These results provide theoretical basis for improving the formability and promoting the applica- tions of TB8 alloy.

关键词： Thermohydrogen processing TB8 alloy Microstructure Compression property

Local Homography Estimation on User-Specified Textureless Regions

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Journal of Computer Science & Technology 2022年第3期37卷 615-625页

作者： zheng Chen Xiao-Nan Fang Song-Hai Zhang Department of Computer Science and Technology Tsinghua UniversityBeijing 100084China

This paper presents a novel deep neural network for designated point tracking(DPT)in a monocular RGB video,*** concretely,the aim is to track four designated points correlated by a local homography on a textureless planar region in the *** can be applied to augmented reality and video editing,especially in the field of video *** methods predict the location of four designated points without appropriately considering the point *** solve this problem,VideoInNet predicts the motion of the four designated points correlated by a local homography within the heatmap prediction *** network refines the heatmaps of designated points through two *** the first stage,we introduce a context-aware and location-aware structure to learn a local homography for the designated plane in a supervised *** the second stage,we introduce an iterative heatmap refinement module to improve the tracking *** propose a dataset focusing on textureless planar regions,named ScanDPT,for training and *** show that the error rate of VideoInNet is about 29%lower than that of the state-of-the-art approach when testing in the first 120 frames of testing videos on ScanDPT.

关键词： homography estimation neural network designated point tracking(DPT)

Glauber gluon effects in soft collinear factorization

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Communications in Theoretical Physics 2022年第11期74卷 106-135页

作者： Gao-Liang Zhou zheng-Xin Yan Xin Zhang Feng Li College of Science Xi'an University of Science and TechnologyXi'an 710054China College of Science Nanjing University of Posts and TelecommunicationsNanjing 210023China

Effects of Glauber gluons,which cause the elastic scattering process between different jets,are studied in the frame of soft-collinear effective *** modes are added into the action before being integrated out,which is helpful in studies on the Glauber couplings of collinear and soft *** is proved that the final state interactions cancel out for processes inclusive *** are interactions with the light cone coordinates x^(+)and x^(-)greater than those of the hard *** eikonalization of Glauber couplings of active particles and absorption of these couplings into soft and collinear Wilson lines are discussed,which is related to the loop level definitions of Glauber gluons *** active-spectator coherence is proved to be harmless to the inclusive summation of spectator-spectator and spectator-soft Glauber *** on this result,spectator-spectator and spectator-soft Glauber exchanges cancel out in the processes considered *** aspects of the cancellation are also discussed to explain relations between the graphic and operator level cancellation of Glauber gluons.

关键词： soft-collinear effective theory QCD factorization Glauber gluons

Evolution of In783 alloy in microstructure and properties enduring different service times

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Rare Metals 2024年第1期43卷 334-341页

作者： Zhong-Shuai Han Jin-Feng Du Jun Liang zheng Zhang School of Material Science and Engineering Beihang UniversityBeijing 100191China Shenhua Guohua(Beijing)Electric Power Research Institute Co. Ltd.Beijing 100025China

Impact, tensile, and fatigue tests were performed in In783 alloy serving 4000, 23,000 and 48,000 h. The microstructure was then analysed by optical microscopy(OM), scanning electron microscopy(SEM), and transmission electron microscopy(TEM) to probe the relationship between microstructure and properties. The results show that a new Ni_(5)Al_(3) phase is found, which grows gradually in β phase with serving time increasing,destroying the martensitic structure of the β phase, and degenerating the toughness of the β phase(approximately13.88% reduction). Therefore, the degradation of the βphase results in a sharp dropping of the resistance to stress accelerated grain boundary oxygen(SAGBO) during serving;thus, the intergranular fracture morphology degree increases with duration of service(almost 40% increase from the fractured surface). In addition, the strength of alloy will be gradually enhanced when the γ'phase becomes relatively bulky with serving time increasing due to considerable distortion of the dislocations as a result of the spacing of individual particles, in which any movement of the dislocation will have to overcome a larger number of obstacles per unit length.

关键词： In783 Microstructure Properties βphase Ni_(5)Al_(3)phase

Smart and fast reinforcement design for anti-dip bedding rock slopes

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第11期15卷 2943-2953页

作者： Yun zheng Congxin Chen Fei Meng Xiaodong Fu Wei Yuan State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China University of Chinese Academy of Sciences Beijing100049China School of Civil Engineering and Architecture Wuhan University of TechnologyWuhan430070China Key Laboratory of Roads and Railway Engineering Safety Control of Ministry of Education Shijiazhuang Tiedao UniversityShijiazhuang050043China

Rock slopes are usually reinforced by a number of rock bolts due to the high efficiency and low ***,where should the rock bolts be installed is still a troublesome *** anti-dip bedding rock slopes(ABRSs),the installation position of rock bolts is a controlling factor that determines the reinforcement *** this work,a theoretical method is firstly proposed for assessing the stability of ABRSs reinforced by rock bolts using a limit equilibrium model.A comparison of theoretical calculations and numerical results was conducted to test the correctness of the theoretical *** on the stability assessment of ABRSs,we introduce adaptive moment estimation method(Adam)to optimize the installation location of rock *** Adam optimizer,the optimal layout of rock bolts with the maximum factor of safety can be determined,and the factor of safety of the slope increases by about 25%using the same amount of rock bolts but with different installation *** proposed method enables the fast stability analysis and supporting design for reinforced ABRSs,which paves the way to smart supporting design of slopes.

关键词： Rock slopes Toppling failure Rock bolts Stability assessment Smart analysis

Optothermally Assembled Nanostructures

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Accounts of Materials Research 2021年第5期2卷 352-363页

作者： Jingang Li Yuebing zheng Materials Science&Engineering Program Texas Materials Instituteand Walker Department of Mechanical EngineeringThe University of Texas at AustinAustinTexas 78712United States

CONSPECTUS:Nanofabrication is one of the core techniques in rapidly evolving nanoscience and *** top-down nanofabrication approaches such as photolithography and electron beam lithography can produce high-resolution nanostructures in a robust ***,these methods usually involve multistep processing and sophisticated instruments and have difficulty in fabricating three-dimensional complex structures of multiple materials and ***,bottom-up techniques have emerged as promising alternatives to fabricating nanostructures via the assembly of individual building *** comparison to top-down lithographical methods,bottom-up assembly features the on-demand construction of superstructures with controllable configurations at single-particle *** size,shape,and composition of chemically synthesized building blocks can also be precisely tailored down to the atomic scale to fabricate multimaterial architectural structures of high *** techniques have been reported to assemble individual nanoparticles into complex structures,such as self-assembly,DNA nanotechnology,patchy colloids,and optically controlled *** them,the optically controlled assembly has the advantages of remote control,site-specific manipulation of single components,applicability to a wide range of building blocks,and arbitrary configurations of the assembled *** this Account,we provide a concise review of our contributions to the optical assembly of architectural materials and structures using discrete nanoparticles as the building *** exploiting entropically favorable optothermal conversion and controlling optothermal−matter interactions,we have developed optothermal assembly techniques to manipulate and assemble individual *** techniques can be operated both in solution and on solid ***,we discuss the opto-thermoelectric assembly(OTA)of colloidal particles into superstructures by co

关键词： structures architectural printing

Analysis and control of micro-stepping characteristics of ultrasonic motor

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Frontiers of Mechanical Engineering 2020年第4期15卷 585-599页

作者： Ning CHEN Jieji zheng Xianliang JIANG Shixun FAN Dapeng FAN College of Intelligence Science and Technology National University of Defence and TechnologyChangsha 410073China

Micro-stepping motion of ultrasonic motors satisfies biomedical applications, such as cell operation and nuclear magnetic resonance, which require a precise compact-structure non-magnetization positioning device. When the pulse number is relatively small, the stopping characteristics have a non-negligible effect on the entire stepwise process. However, few studies have been conducted to show the rule of the open-loop stepwise motion, especially the shutdown stage. In this study, the modal differences of the shutdown stage are found connected with amplitude and velocity at the turn-off instant. Changes of the length in the contact area and driving zone as well as the input currents, vibration states, output torque, and axial pressure are derived by a simulation model to further explore the rules. The speed curves and vibration results in functions of different pulse numbers are compared, and the stepwise motion can be described by a two-stage two-order transfer function. A test workbench based on the Field Programmable Gate Array is built for acquiring the speed, currents, and feedback voltages of the startup–shutdown stage accurately with the help of its excellent synchronization performances. Therefore, stator vibration, rotor velocity, and terminal displacements under different pulse numbers can be compared. Moreover, the two-stage two-order model is identified on the stepwise speed curves, and the fitness over 85% between the simulation and test verifies the model availability. Finally, with the optimization of the pulse number, the motor achieves 3.3 µrad in clockwise and counterclockwise direction.

关键词： ultrasonic motor stepping characteristics pulse number control synchronous acquisition system precise positioning