检索结果-南通市图书馆

Development of a Front End Array for Broadband Phased Array Receiver

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4期24卷 60-70页

作者： Kai Wang Liang Cao Jun Ma Xue-Feng Duan Hao Yan mao-zheng chen Yun-Wei Ning Xinjiang Astronomical Observatory Chinese Academy of SciencesUrumqi 8300lChina University of the Chinese Academy of Sciences Beijing 100049China Xinjiang Key Laboratory of Microwave Technology Urumqi 830011China

The receiver is a signal receiving device placed at the focus of the *** order to improve the observation efficiency,the concept of phased array receiver has been proposed in recent years,which places a small phased array at the focal plane of the reflector,and flexible pattern and beam scanning functions can be achieved through a beamforming *** combined with the element multiplexing,all beams within the entire field of view can be observed simultaneously to achieve continuous sky *** article focuses on the front-end array of phased array receiver at 0.7-1.8 GHz for QiTai Telescope,and designs a Vivaldi antenna array of PCB structure with dual line *** polarization antenna is designed to arrange in a rectangle manner by 11×*** on the simulation results of the focal field,32,18,and eight elements were selected to form one beam at 0.7,1.25,and1.8 *** analog beamforming network was constructed,and the measured gains of axial beam under uniform weighting were 19.32,13.72,and 15.22 *** the beam scanning method of reflector antenna,the pattern test of different position element sets required for PAF beam scanning was carried out under independent *** pattern optimization at 1.25 GHz was carried out by weighting method of conjugate field *** with uniform weighting,the gain,sidelobe level,and main beam direction under conjugate field matching have been *** the above test and simulation results are slightly different,which is related to the passive array and laboratory testing condition,the relevant work has accumulated experience in the development of the front-end array for the phased array receiver,and has good guiding significance for future performance verification after the array is installed on the telescope.

关键词： telescopes instrumentation:detectors techniques:radar astronomy

Design and Application of an S-band Fast Radio Bursts Search Pipeline for the Nanshan 26 m Radio Telescope

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7期24卷 114-120页

作者： Yan-Ling Liu mao-zheng chen Jian Li Jian-Ping Yuan Rai Yuen Zhi-Yong Liu Hao Yan Wen-Long Du Nan-Nan Zhai Xinjiang Astronomical Observatory Chinese Academy of Sciences Xinjiang Key Laboratory of Microwave Technology University of Chinese Academy of Sciences

Fast radio bursts(FRBs) are among the most studied radio transients in astrophysics, but their origin and radiation mechanism are still unknown. It is a challenge to search for FRB events in a huge amount of observational data with high speed and high accuracy. With the rapid advancement of the FRB research process, FRB searching has changed from archive data mining to either long-term monitoring of the repeating FRBs or all-sky surveys with specialized equipments. Therefore, establishing a highly efficient and high quality FRB search pipeline is the primary task in FRB research. Deep learning techniques provide new ideas for FRB search processing. We have detected radio bursts from FRB 20201124A in the L-band observational data of the Nanshan 26 m radio telescope(NSRT-26m) using the constructed deep learning based search pipeline named dispersed dynamic spectra search(DDSS). Afterwards, we further retrained the deep learning model and applied the DDSS framework to S-band observations. In this paper, we present the FRB observation system and search pipeline using the S-band *** carried out search experiments, and successfully detected the radio bursts from the magnetar SGR J1935+2145and FRB 20220912A. The experimental results show that the search pipeline can complete the search efficiently and output the search results with high accuracy.

关键词： methods: data analysis methods: observational radio continuum: general

Single image defogging via multi-exposure image fusion and detail enhancement

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Safety Science and Resilience 2024年第1期5卷 37-46页

作者： Wenjing mao Dezhi zheng Minze chen Juqiang chen School of Information and Electronics Advanced Research Institute of Multidisciplinary ScienceBeijing Institute of TechnologyBeijing100081China Chinese Aeronautical Establishment Beijing100012China

Outdoor cameras play an important role in monitoring security and social *** a common weather phenomenon,haze can easily affect the quality of camera shooting,resulting in loss and distortion of image *** paper proposes an improved multi-exposure image fusion defogging technique based on the artificial multi-exposure image fusion(AMEF)***,the foggy image is adaptively exposed,and the fused image is subsequently obtained via multiple *** fusion weight is determined by the saturation,contrast,and ***,the image fused by a multi-scale Laplacian algorithm is enhanced with simple adaptive details to obtain a clearer defogging *** is subjectively and objectively verified that this algorithm can obtain more image details and distinct picture colors without a priori information,effectively improving the defogging ability.

关键词： Image defogging Multi-scale fusion Laplacian pyramid Adaptive detail enhancement

A Search Technique Based on Deep Learning for Fast Radio Bursts and Initial Results for FRB 20201124A with the NSRT

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

Research in Astronomy and Astrophysics 2022年第10期22卷 77-85页

作者： Yan-Ling Liu Jian Li Zhi-Yong Liu mao-zheng chen Jian-Ping Yuan Na Wang Rai Yuen Hao Yan Xinjiang Astronomical observatory Chinese Academy of SciencesUrumqi 830011China University of Chinese Academy of Sciences Beijing 100049China Key Laboratory of Radio Astronomy Chinese Academy of SciencesNanjing 210033China Xinjiang Key Laboratory of Microwave Technology Urumqi 830011China

The origin and phenomenology of Fast Radio Bursts(FRBs) remain unknown. Fast and efficient search technology for FRBs is critical for triggering immediate multi-wavelength follow-up and voltage data dump. This paper proposes a dispersed dynamic spectra search(DDSS) pipeline for FRB searching based on deep learning, which performs the search directly from observational raw data, rather than relying on generated FRB candidates from single-pulse search algorithms that are based on de-dispersion. We train our deep learning network model using simulated FRBs as positive and negative samples extracted from the observational data of the Nanshan 26 m radio telescope(NSRT)at Xinjiang Astronomical Observatory. The observational data of PSR J1935+1616 are fed into the pipeline to verify the validity and performance of the pipeline. Results of the experiment show that our pipeline can efficiently search single-pulse events with a precision above 99.6%, which satisfies the desired precision for selective voltage data dump. In March 2022, we successfully detected the FRBs emanating from the repeating case of FRB 20201124A with the DDSS pipeline in L-band observations using the NSRT. The DDSS pipeline shows excellent sensitivity in identifying weak single pulses, and its high precision greatly reduces the need for manual review.

关键词： radio continuum general-methods data analysis-methods observational

MiR-30a-5p alleviates LPS-induced HPMEC injury through regulation of autophagy via Beclin-1

在线全文

学校读者我要写书评

暂无评论

BIOCELL 2024年第3期48卷 431-441页

作者： RAN PAN JIAYAN mao YUELIANG zheng WEI chen JUNPING GUO LIJUN WANG Rainbowfish Rehabilitation and Nursing School Hangzhou Vocational&Technical CollegeHangzhou310018China Cancer Institute of Integrated Traditional Chinese and Western Medicine Key Laboratory of Cancer Prevention and Therapy Combining Traditional Chinese and Western MedicineZhejiang Academy of Traditional Chinese MedicineHangzhou310012China Geriatric Medicine Center Department of EndocrinologyZhejiang Provincial People’s Hospital(Affiliated People’s Hospital)Hangzhou Medical CollegeHangzhou310015China

Background:Sepsis,a type of systemic disease,can impact nearly all organs,tissues and *** them,endothelial cells are amongst theﬁrst to be affected and respond to the *** this study,we investigated the protective effects of microRNA-30a-5p(miR-30a-5p)on human pulmonary microvascular endothelial cells(HPMECs)treated with lipolysaccharide(LPS).Methods:An in vitro model of sepsis was established in HPMECs with the use of *** with different tools(mimetic and inhibitor)to modify miR-30a-5p *** viability,proliferation and apoptosis were detected by the CCK-8 assay,the EdU kit andﬂuorescence staining,*** autophagy-related protein and mRNA expression,the number of autophagosomes were separately examined through Western blot analysis,qPT-PCR and confocal *** and the luciferase reporter assays were used to probe target genes interacting with ***:LPS caused a reduction in the viability and proliferation of HPMECs,as well as an elevation in the number of apoptotic ***,we observed that miR-30a-5p might play a role in preventing LPS-induced inhibition of cell damage and decreasing HPMEC apoptosis,suggesting the potential function of miR-30a-5p in this injury ***,we conﬁrmed that miR-30a-5p exerts its protective effect by regulating cell autophagy,possibly by targeting ***:Our study provided evidence that autophagy is a crucial aspect in the protective role of miR-30a-5p against LPS-induced HPMEC injury,identifying a promising target for sepsis-related endothelial cell injury.

关键词： Sepsis Endothelial cells MicroRNA Systemic inflammatory response syndrome

Equilibrium Strategy of the Pursuit-Evasion Game in Three-Dimensional Space

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

IEEE/CAA Journal of Automatica Sinica 2024年第2期11卷 446-458页

作者： Nuo chen Linjing Li Wenji mao School of Artificial Intelligence University of Chinese Academy of SciencesBeijing 100049 Institute of Automation Chinese Academy of SciencesBeijing 100190China

The pursuit-evasion game models the strategic interaction among players, attracting attention in many realistic scenarios, such as missile guidance, unmanned aerial vehicles, and target defense. Existing studies mainly concentrate on the cooperative pursuit of multiple players in two-dimensional pursuit-evasion games. However, these approaches can hardly be applied to practical situations where players usually move in three-dimensional space with a three-degree-of-freedom control. In this paper,we make the first attempt to investigate the equilibrium strategy of the realistic pursuit-evasion game, in which the pursuer follows a three-degree-of-freedom control, and the evader moves freely. First, we describe the pursuer's three-degree-of-freedom control and the evader's relative coordinate. We then rigorously derive the equilibrium strategy by solving the retrogressive path equation according to the Hamilton-Jacobi-Bellman-Isaacs(HJBI) method, which divides the pursuit-evasion process into the navigation and acceleration phases. Besides, we analyze the maximum allowable speed for the pursuer to capture the evader successfully and provide the strategy with which the evader can escape when the pursuer's speed exceeds the threshold. We further conduct comparison tests with various unilateral deviations to verify that the proposed strategy forms a Nash equilibrium.

关键词： Differential game equilibrium strategy pursuit-evasion game threedegree-of-freedom control

A semi-analytical model for coupled flow in stress-sensitive multi-scale shale reservoirs with fractal characteristics

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 327-342页

作者： Qian Zhang Wen-Dong Wang Yu-Liang Su Wei chen zheng-Dong Lei Lei Li Yong-mao Hao Key Laboratory of Unconventional Oil&Gas Development(China University of Petroleum(East China)) Ministry of EducationQingdao266580ShandongChina School of Petroleum Engineering China University of Petroleum(East China)Qingdao266580ShandongChina Shale Oil Development Branch Changqing Oilfield CompanyPetroChinaQingyang745708GansuChina PetroChina Research Institute of Petroleum Exploration&Development Beijing100083China

A large number of nanopores and complex fracture structures in shale reservoirs results in multi-scale flow of oil. With the development of shale oil reservoirs, the permeability of multi-scale media undergoes changes due to stress sensitivity, which plays a crucial role in controlling pressure propagation and oil flow. This paper proposes a multi-scale coupled flow mathematical model of matrix nanopores, induced fractures, and hydraulic fractures. In this model, the micro-scale effects of shale oil flow in fractal nanopores, fractal induced fracture network, and stress sensitivity of multi-scale media are considered. We solved the model iteratively using Pedrosa transform, semi-analytic Segmented Bessel function, Laplace transform. The results of this model exhibit good agreement with the numerical solution and field production data, confirming the high accuracy of the model. As well, the influence of stress sensitivity on permeability, pressure and production is analyzed. It is shown that the permeability and production decrease significantly when induced fractures are weakly supported. Closed induced fractures can inhibit interporosity flow in the stimulated reservoir volume (SRV). It has been shown in sensitivity analysis that hydraulic fractures are beneficial to early production, and induced fractures in SRV are beneficial to middle production. The model can characterize multi-scale flow characteristics of shale oil, providing theoretical guidance for rapid productivity evaluation.

关键词： Multi-scale coupled flow Stress sensitivity Shale oil Micro-scale effect Fractal theory

Multidimensional hollow SiO_(2)/C nanofibers modified by magnetic nanocrystals for electromagnetic energy conversion and lithium battery storage

在线全文

学校读者我要写书评

暂无评论

Nano Research 2024年第8期17卷 7301-7314页

作者： chen Han Qi zheng Juncheng Jin Jiajia Zhang Wen-Qiang Cao Kun Xiang Min Zhang mao-Sheng Cao Anhui Provincial Laboratory of Biomimetic Sensor and Detecting Technology College of Materials and Chemical EngineeringWest Anhui UniversityLu’an 237012China School of Materials Science and Engineering Beijing Institute of TechnologyBeijing 100081China Department of Physics Beijing Technology and Business UniversityBeijing 100048China

Multifunctional materials are powerful tools to support the advancement of energy conversion *** with prominent electromagnetic and electrochemical properties can realize the conversion of electromagnetic energy and solve the subsequent storage ***,an electrospinning-thermal reduction method is employed to construct ultrafine nickel nanoparticle modified porous SiO_(2)/C(Ni-SiO_(2)/C)hollow nanofibers as promising materials for applications in both electromagnetic wave absorption(EMA)and lithium-ion ***,when used as an EMA material,the reflection loss(RL)of Ni-SiO_(2)/C can reach−47.8 dB at 15.8 GHz with a matching thickness of 2.2 *** excellent microwave absorption performance can be attributed to the enhanced conduction loss,polarization relaxation,synergistic magnetic loss,and preferred impedance matching,which result from multi-component magnetic/dielectric synergy and the unique interconnected multidimensional hollow ***,the electronic conductivity and electrochemical activity of the samples are significantly enhanced due to the uniform distribution of ultrafine Ni nanoparticles in the amorphous SiO_(2)/C ***,the hierarchical hollow porous structure provides sufficient free space for volume change during lithiation/delithiation ***,the Ni-SiO_(2)/C nanocomposite exhibits a high reversible capacity of 917.6 mAh·g^(−1)at 0.1 A·g^(−1).At a high current density of 2 A·g^(−1),a capacity of 563.9 mAh·g^(−1)can be maintained after 300 *** energy conversion-storage device is designed to store waste electromagnetic energy in the form of useful electrical *** work inspires the development of high-performance bifunctional materials.

关键词： Ni-SiO_(2)/C nanofiber electromagnetic absorption lithium-ion storage electrospinning multidimensional structure

Can whole steps of grain production be outsourced? Empirical analysis based on the three provinces of Jiangsu,Jilin,and Sichuan in China

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 Integrative Agriculture 2024年第1期23卷 336-347页

作者： Jiacheng Liu Shengzhi mao Qiufen zheng Zhigang Xu School of Finance and Taxation Nanjing University of Finance and EconomicsJiangsu 210023China School of Economics Southwestern University of Finance and EconomicsSichuan 611130China School of Economics and Management Nanjing Agricultural UniversityJiangsu 210095China

Certain outsourcing services for agricultural management in China,such as pest control in grain production,have experienced prolonged sluggishness,contrasting with the relatively high level of outsourcing services observed in harvesting,land preparation,and *** study examines the feasibility of implementing whole-step outsourcing in grain production by conducting a case study of rice and maize production in Jiangsu,Jilin,and Sichuan provinces in *** provision of outsourcing services hinges on two essential conditions:technological advancements fostering specialized production and economies of scale,coupled with a market size sufficient to realize the aforementioned potential economies of *** results showed that outsourcing pest control or harvesting services had varying economies of *** outsourcing services in pest control were less common than in harvesting services,and their marginal growth space of the economies of scale with technological change was also *** by the operational characteristics of pest control itself,the market scale of its professional services is ***,achieving the whole-step outsourcing of grain production necessitates not only technological innovation but also effective policy interventions to overcome the constraints of market *** interventions include(1)optimizing crop layouts between planning regions and reducing land fragmentation and(2)supplying timely and effective inter-regional agricultural information for service providers aided by information technology.

关键词： outsourcing services economy of scale technical conditions market scale