检索结果-南通市图书馆

Seismic tomography of the crust and upper mantle in the Bohai Bay Basin and its adjacent regions

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2007年第12期50卷 1810-1822页

作者： ZHANG Ling liu JinSong HAO TianYao liu JianHua xu yi Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China Gocad Research Group Rue Doyen M. Roubault 54501 Nancy France Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China

In the Bohai Bay Basin and its adjacent regions(112°―124°E,34°―42°N),there exists abundant gas-petroleum while modern inter-plate seismic activity is *** the tectonic structure of this region is very complicated,plenty of geological,geophysical and geochemical data and results are obtained through previous *** the basis of absorbing previous results,especially various kinds of geological and geophysical results,we collect and process the arrival time of P-wave phases of local events and tele-seismic events recorded by the station within this region from 1978 to 2004,build the responding initial model,and image the velocity structure of the crust and upper mantle of this region via *** perturbation images of various depths and velocity profiles imply that the velocity structure of the crust and upper mantle in the Bohai Bay Basin and its adjacent regions is mainly influenced by the surface tectonic units,and is characterized by "Stripped along east-west,and zoned along south-north";some large-scaled faults penetrate Moho and lithosphere,and provide the channels for the basic lava or hot mass upwelling from the mantle.

关键词： Bohai Bay Basin, tomography, crust and upper mantle

Electroacupuncture effects on cortical neurons, as well as Janus kinase 2-signal transducer and activator of transcription 3 signal transduction pathway, in a rat model of cerebral ischemia

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2012年第6期7卷 457-462页

作者： Rong liu Nenggui xu Wei yi Kangbai Huang Guangzhou University of Chinese Medicine Guangzhou 510405 Guangdong Province China

The present study established a model of focal cerebral ischemia through heat-coagulation induced occlusion of the middle cerebral artery. Following electroacupuncture at Baihui （GV20） and Dazhui （GV14）, or intracerebroventricular infusion of AG490, a Janus kinase 2 phosphorylation inhibitor, the amount of necrotic or degenerated neurons in the ischemic cerebral cortex decreased, neuronal swelling was ameliorated, and expression of phosphorylated Janus kinase 2 and signal transducer and activator of transcription 3 decreased Results confirmed that electroacupuncture promoted neuronal repair in the cerebral cortex by reducing expression of phosphorylated Janus kinase 2 and signal transducer and activator of transcription 3, as well as weakening the phosphorylated activation, thereby blocking abnormal activation of the Janus kinase 2- signal transducer and activator of transcription 3 signal transduction pathway.

关键词： cerebral ischemia JAK2-STAT3 neurons electroacupuncture AG490

A stable staggered-grid finite-difference scheme for acoustic modeling beyond conventional stability limit

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2024年第1期21卷 182-194页

作者： Jing-yi xu Yang liu National Key Laboratory of Petroleum Resources and Engineering China University of Petroleum(Beijing)Beijing 102249China China University of Petroleum(Beijing) Karamay CampusKaramay 834000XinjiangChina

Staggered-grid finite-difference(SGFD)schemes have been widely used in acoustic wave modeling for geophysical *** improved methods are proposed to enhance the accuracy of numerical ***,these methods are inevitably limited by the maximum Courant-Friedrichs-Lewy(CFL)numbers,making them unstable when modeling with large time sampling intervals or small grid *** solve this problem,we extend a stable SGFD scheme by controlling SGFD dispersion relations and maximizing the maximum CFL ***,to improve modeling stability,we minimize the error between the FD dispersion relation and the exact relation in the given wave-number region,and make the FD dispersion approach a given function outside the given wave-number area,thus breaking the conventional limits of the maximum CFL ***,to obtain high modeling accuracy,we use the SGFD scheme based on the Remez algorithm to compute the FD *** addition,the hybrid absorbing boundary condition is adopted to suppress boundary reflections and we find a suitable weighting coefficient for the proposed *** derivation and numerical modeling demonstrate that the proposed scheme can maintain high accuracy in the modeling process and the value of the maximum CFL number of the proposed scheme can exceed that of the conventional SGFD scheme when adopting a small maximum effective wavenumber,indicating that the proposed scheme improves stability during the modeling.

关键词： Acoustic wave Staggered-grid finite-difference(SGFD) modeling Courant-friedrichs-lewy(CFL)number Stability

DRILLING CHARACTERISTICS OF COMBINATIONS OF DIFFERENT HIGH PRESSURE JET NOZZLES

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2011年第3期23卷 384-390页

作者： ZHANG Yu-ying liu Yong-wang xu yi-ji REN Jian-hua College of Petroleum Engineering China University of Petroleum （East China） Dongying 257061 China

The high speed fluid jet for directly or indirectly breaking rock is one of the most effective ways to improve the deep penetration rate. In order to maximize the efficiency of energy use, the flow characteristics of different combinations of high pressure jet nozzles are analyzed through numerical simulations. According to the velocity vectors at the bottom and the bottom hole pressure diagram, the effects of the high pressure nozzle combinations on the flow structure and the penetration rate are analyzed. It is shown that the combination of three vertical edge nozzles is very efficient, but inefficient in cleaning the bottom hole and eroding the wall. The jet velocity is 400 m/s and the radius is 5 mm, with a center nozzle added, the problem can be solved, but the high-pressure fluid displacement would increase. The center nozzle＇s jet velocity is 200 m/s and the radius is 8 ram, the combination of two vertical edge nozzles and a center tilt nozzle or that of a vertical edge nozzle and a center tilt nozzle would provide a flow structure favorable for drilling. The angle of inclination is 10°. To take advantage of high pressure jet energy to improve the efficiency of drilling, it is important to select a suitable nozzle combination according real conditions.

关键词： Rate Of Penetration (ROP) rock breaking high pressure jet nozzle combination numerical simulation energy use

四川省眉山市29家托育机构服务能力的现状调查

在线全文

学校读者我要写书评

暂无评论

中国妇幼卫生杂志 2024年第4期15卷 55-60页

作者：陈杰刘绪义宋文健杨璐周群英彭懿眉山市妇幼保健院四川眉山620010

目的了解四川省眉山市婴幼儿照护服务能力现状,为政府后续托育服务政策的制定和完善提供参考依据。方法采用横断面研究的方法,于2023年5-6月收集四川省眉山市29家托育机构婴幼儿照护服务能力的情况,比较不同类型托育机构在办托条件、人... 详细信息

目的了解四川省眉山市婴幼儿照护服务能力现状,为政府后续托育服务政策的制定和完善提供参考依据。方法采用横断面研究的方法,于2023年5-6月收集四川省眉山市29家托育机构婴幼儿照护服务能力的情况,比较不同类型托育机构在办托条件、人力资源、卫生保健工作、收费与托位使用情况上的差异。结果29家托育机构中室外活动场地人均使用面积≥3 m~2的机构占93%,不同类型机构间的比较差异有统计学意义(P0.05)。在班型开设比例上,不同类型机构在托小班、乳儿班、混龄班开设上的比较差异有统计学意义(P0.05)。在设施设备完整配备率上,不同类型机构照护设备的比较差异有统计学意义(P0.05)。班级保育人员配置以2教1保为主(62%),专职卫生保健人员配备率为55%。托育机构从业人员年平均工资低于2022年眉山市城镇全部单位就业人员年平均工资,差异有统计学意义(P0.05)。结论四川省眉山市婴幼儿照护服务存在办托条件参差不齐、人员配备不均衡、医育结合服务供需不平衡、收费与托位使用率存在矛盾的问题。建议持续加大对各类托育服务支持的保障力度,加强托育服务人才的队伍建设,扩大医育结合服务有效供给,着重提升机构运营管理能力,全面推进婴幼儿照护服务能力的高质量发展。

关键词：婴幼儿照护服务政策建议调查研究

Analog spatiotemporal feature extraction for cognitive radio-frequency sensing with integrated photonics

在线全文

学校读者我要写书评

暂无评论

Light(Science & Applications) 2024年第3期13卷 478-487页

作者： Shaofu xu Binshuo liu Sicheng yi Jing Wang Weiwen Zou State Key Laboratory of Advanced Optical Communication Systems and Networks Intelligent Microwave Lightwave Integration Innovation Center(imLic)Department of Electronic EngineeringShanghai Jiao Tong UniversityShanghaiChina

Analog feature extraction(AFE)is an appealing strategy for low-latency and efficient cognitive sensing systems since key features are much sparser than the Nyquist-sampled ***,applying AFE to broadband radio-frequency(RF)scenarios is challenging due to the bandwidth and programmability bottlenecks of analog electronic ***,we introduce a photonics-based scheme that extracts spatiotemporal features from broadband RF signals in the analog *** feature extractor structure inspired by convolutional neural networks is implemented on integrated photonic circuits to process RF signals from multiple antennas,extracting valid features from both temporal and spatial *** of the tunability of the photonic devices,the photonic spatiotemporal feature extractor is trainable,which enhances the validity of the extracted ***,a digital-analog-hybrid transfer learning method is proposed for the effective and low-cost training of the photonic feature *** validate our scheme,we demonstrate a radar target recognition task with a 4-GHz instantaneous *** results indicate that the photonic analog feature extractor tackles broadband RF signals and reduces the sampling rate of analog-to-digital converters to 1/4 of the Nyquist sampling while maintaining a high target recognition accuracy of 97.5%.Our scheme offers a promising path for exploiting the AFE strategy in the realm of cognitive RF sensing,with the potential to contribute to the efficient signal processing involved in applications such as autonomous driving,robotics,and smart factories.

关键词： scheme driving smart

Equivalent Impedance Parameter Calculation of Three-phase Symmetrical Loads for Harmonic Source Location

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 Modern Power Systems and Clean Energy 2024年第1期12卷 251-260页

作者： yi Zhang Bijie liu Caihua Lin Zhenguo Shao Yuncong xu the Department of Electrical Engineering and Automation Fuzhou UniversityFuzhouChina State Grid Fujian Electric Power Research Institute FuzhouChina

The equivalent impedance parameters of loads have been widely used to identify and locate the harmonic ***,the existing calculation methods suffer from outliers caused by the zero-crossing of the *** outliers can result in inaccuracy and unreliability of harmonic source *** address this issue,this paper proposes an innovative method of equivalent impedance parameter calculation of three-phase symmetrical loads that avoid *** correctness and effectiveness of the proposed method are verified by simulations on Simulink using actual monitoring *** results show that the proposed method is not only simple and easy to implement but also highly accurate.

关键词： abc-αβtransformation equivalent impedance parameters of load harmonic source location nonlinear load power quality

How to build a habitable planet:an interview with Charles H. Langmuir

在线全文

学校读者我要写书评

暂无评论

National Science Review 2024年第6期11卷 76-80页

作者： yi-Gang xu the Guangzhou Institute of Geochemistry Chinese Academy of Sciences

Earth is the only known habitable planet in the solar system. Understanding how Earth developed its unique habitability has been the frontier of Earth sciences and has become one of the main themes of current deep-space explorations. What are the decisive factors that led to a habitable planet? What is the role of solid Earth processes in the origin of life and in modulating the surface environment? Are Earth’s habitability studies relevant to current challenges that human beings face? These questions have attracted the interest of both scientists and the public alike.

关键词： Earth (planet)

Enhancing competency of clinical research nurses:A comprehensive training and evaluation framework

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

World Journal of Clinical Cases 2024年第7期12卷 1378-1381页

作者： Yang-Xi liu yi xu Tumor Interventional Department Taizhou Municipal HospitalTaizhou 318099Zhejiang ProvinceChina

The Sun et al's training program for clinical research nurses(CRNs)in the World Journal of Clinical Cases is a comprehensive and scientific *** includes structured frameworks for CRN training,aiming to improve CRN *** program emphasizes practical abilities,updates training content,and improves evaluation *** cultivation of CRN talents focuses on enhancing the training system,establishing a multifaceted evaluation framework,and continuously refining the training *** feedback and evalua-tion are essential to improve CRNs'competency in practical settings.

关键词： Clinical research nurse Framework Nurse Operations Practice Structure