检索结果-南通市图书馆

Mars Ion and Neutral Particle Analyzer (MINPA) for Chinese Mars Exploration Mission (Tianwen-1): Design and ground calibration

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Earth and Planetary Physics 2020年第4期4卷 333-344页

作者： LingGao Kong AiBing Zhang Zhen Tian XiangZhi Zheng WenJing Wang Bin Liu Peter Wurz Daniele Piazza Adrian Etter Bin Su YaYa An JianJing Ding WenYa Li Yong Liu Lei Li YiRen Li xu tan YueQiang Sun National Space Science Center Chinese Academy of SciencesBeijing 100190China Beijing Key Laboratory of Space Environment Exploration Beijing 100190China Key Laboratory of Science and Technology on Space Environment Situational Awareness Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Physics Institute University of BernBern 3012Switzerland State Key Laboratory of Space Weather Beijing 100190China University of Science and Technology of China Hefei 230026China National Astronomical Observatories Chinese Academy of SciencesBeijing 100012China

The main objective of the Mars Ion and Neutral Particle Analyzer(MINPA)aboard the Chinese Mars Exploration Mission(Tianwen-1)is to study the solar wind-Mars interaction by measuring the ions and energetic neutral atoms(ENAs)near Mars.The MINPA integrates ion and ENA measurements into one sensor head,sharing the same electronics box.The MINPA utilizes a standard toroidal top-hat electrostatic analyzer(ESA)followed by a time of flight(TOF)unit to provide measurement of ions with energies from 2.8 eV to 25.9 keV and ENAs from 50 eV to 3 keV with a base time resolution of 4 seconds.Highly polished silicon single crystal substrates with an Al2O3 film coating are used to ionize the ENAs into positive ions.These ions can then be analyzed by the ESA and TOF,to determine the energy and masses of the ENAs.The MINPA provides a 360°×90°field of view(FOV)with 22.5°×5.4°angular resolution for ion measurement,and a 360°×9.7°FOV with 22.5°×9.7°angular resolution for ENA measurement.The TOF unit combines a-15 kV acceleration high voltage with ultra-thin carbon foils to resolve H+,He2+,He+,O+,O2+and CO2+for ion measurement and to resolve H and O(≥16 amu group)for ENA measurement.Here we present the design principle and describe our ground calibration of the MINPA.

关键词： Mars ion energetic neutral atom electrostatic analyzer time of flight

Overview of the Mars climate station for Tianwen-1 mission

在线全文

学校读者我要写书评

暂无评论

Earth and Planetary Physics 2020年第4期4卷 371-383页

作者： YongQing Peng LeiBo Zhang ZhiGuo Cai ZhaoGang Wang HaiLong Jiao DongLi Wang XianTao Yang LianGuo Wang xu tan Feng Wang Jing Fang ZhouLu Sun HongLiang Feng XiaoRui Huang Yan Zhu Ming Chen LiangHai Li YanHua Li Beijing Research Institute of Telemetry Beijing 100076China National Space Science Center Chinese Academy of SciencesBeijing 100012China National Astronomical Observatories Chinese Academy of SciencesBeijing 100012China Chinese Academy of Aerospace Electronics Technology Beijing 100012China

The background and scientific objectives of the Mars Climate Station(MCS)for Tianwen-1 are introduced,accompanied by a comparative review of the status of related meteorological observation missions and of advanced sensing technologies.As one of the China Tianwen-1 Mission’s principal scientific payloads,the MCS contains four measurement sensors and one electronic processing unit that are specially designed to measure local temperature,pressure,wind,and sound on the Martian surface.The MCS’s measurement principles,technical schemes,ground calibration techniques,and adaptability evaluation to the Mars surface environment of MCS are introduced in details.The conclusion presents measurement performance specifications of the MCS,based on ground test results,that will provide guidance to future research based on data from the Tianwen-1 and later Mars missions.

关键词： Tianwen-1 Mars exploration Mars climate station

Emergence of machine language: towards symbolic intelligence with neural networks

在线全文

学校读者我要写书评

暂无评论

National Science Review 2024年第4期11卷 27-30页

作者： Yuqi Wang xu-Yao Zhang Cheng-Lin Liu Tieniu tan Zhaoxiang Zhang State Key Laboratory of Multimodal Artificial Intelligence Systems Institute of AutomationChinese Academy of Sciences

Representation learning is a core issue in artificial intelligence (AI). Currently,there exists a disparity in the choice of representation between humans and machines. Humans rely on discrete language for communicati...

关键词：

Requirements ranking based on crowd-sourcing high-end product USs

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 Systems Engineering and Electronics 2024年第1期35卷 94-104页

作者： MA Yufeng DOU Yajie xu Xiangqian JIA Qingyang tan Yuejin College of Systems Engineering National University of Defense TechnologyChangsha 410003China

Based on the characteristics of high-end products,crowd-sourcing user stories can be seen as an effective means of gathering requirements,involving a large user base and generating a substantial amount of unstructured feedback.The key challenge lies in transforming abstract user needs into specific ones,requiring integration and analysis.Therefore,we propose a topic mining-based approach to categorize,summarize,and rank product requirements from user stories.Specifically,after determining the number of story categories based on py LDAvis,we initially classify“I want to”phrases within user stories.Subsequently,classic topic models are applied to each category to generate their names,defining each post-classification user story category as a requirement.Furthermore,a weighted ranking function is devised to calculate the importance of each requirement.Finally,we validate the effectiveness and feasibility of the proposed method using 2966 crowd-sourced user stories related to smart home systems.

关键词： high-end product complex system crowd-sourcing user stories topic mining requirements ranking

Surface roughness classification using light scattering matrix and deep learning

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2024年第2期67卷 520-535页

作者： SUN Hao tan Wei RUAN YiXiao BAI Long xu JianFeng State Key Laboratory of Intelligent Manufacturing Equipment and Technology School of Mechanical Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China Wuhan Digital Design and Manufacturing Innovation Center Co. LtdWuhan 430074China

High-quality optical components have been widely used in various applications;thus,extremely high beam quality is required.Moreover,surface roughness is a key indicator of the surface quality.In this study,the angular distribution of light scattering field intensity was obtained for surfaces having different roughness profiles based on the finite difference time domain(FDTD)method,and the results were compared with those obtained using the generalized Harvey-Shack(GHS)theory.It was shown that the FDTD approach can be used for an accurate simulation of the scattered field of a rough surface,and the superposition of results obtained from many surfaces that have the same roughness level was in good agreement with the result given by the analytic GHS model.A light scattering matrix(LSM)method was proposed based on the FDTD simulation results that could obtain rich surface roughness information.The classification effect of LSM was compared with that of the single-incidence scattering distribution(SISD)based on a ResNet-50 deep learning network.The classification accuracy of the model trained with the LSM dataset was obtained as 95.74%,which was 23.40%higher than that trained using the SISD dataset.Moreover,the effects of different noise types and filtering methods on the classification performance were analyzed,and the LSM was also shown to improve the robustness and generalizability of the trained surface roughness classifier.Overall,the proposed LSM method has important implications for improving the data acquisition scheme of current light scattering measurement systems,and it also has the potential to be used for detection and characterization of surface defects of optical components.

关键词： surface roughness FDTD simulation GHS theory deep learning light scattering matrix

Half-global discretization algorithm based on rough set theory

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2009年第2期20卷 339-347页

作者： tan xu Chen Yingwu School of Information Systems & Management National Univ. of Defense Technology Changsha 410073 P. R. China

It is being widely studied how to extract knowledge from a decision table based on rough set theory. The novel problem is how to discretize a decision table having continuous attribute. In order to obtain more reasonable discretization results, a discretization algorithm is proposed, which arranges half-global discretization based on the correlational coefficient of each continuous attribute while considering the uniqueness of rough set theory. When choosing heuristic information, stability is combined with rough entropy. In terms of stability, the possibility of classifying objects belonging to certain sub-interval of a given attribute into neighbor sub-intervals is minimized. By doing this, rational discrete intervals can be determined. Rough entropy is employed to decide the optimal cut-points while guaranteeing the consistency of the decision table after discretization. Thought of this algorithm is elaborated through Iris data and then some experiments by comparing outcomes of four discritized datasets are also given, which are calculated by the proposed algorithm and four other typical algorithras for discritization respectively. After that, classification rules are deduced and summarized through rough set based classifiers. Results show that the proposed discretization algorithm is able to generate optimal classification accuracy while minimizing the number of discrete intervals. It displays superiority especially when dealing with a decision table having a large attribute number.

关键词： half-global discretization continuous condition attributes correlation coefficient rough entropy stability rough set theory

Whose Aid is Beneficial to Firms'Exports?Evidence from a Post-disaster Aid Experiment in China

在线全文

学校读者我要写书评

暂无评论

China & World Economy 2024年第2期32卷 73-96页

作者： tan Li Qing Liu Lihe xu School of International Business Southwestern University of Finance and EconomicsChina School of Economics Renmin University of ChinaChina Institute of Studies for the Greater Bay Area Guangdong University of Foreign StudiesChina

Post-disaster aid is widely regarded as important in helping local recovery and development.This paper examines the effectiveness of post-disaster aid on exports,which are a driving factor of economic development.It reports a natural experiment in China–the case of post-disaster aid following the Wenchuan earthquake in 2008–to examine how donors'experiences affected the exports of manufacturing firms in disaster-stricken counties.The export experience of the donor was important.Aid coming from donors with more export experience was more beneficial to the exports of firms in recipient counties than aid from less experienced donors.“Learning from the donor”is a potential channel through which this effect occurred.That is,firms in recipient counties learned from donors'export experience by exporting more products similar to those of donors,exporting more to the destination countries of donors,and participating in the donors'supply-chain networks by exporting more of the donors'exports.Such“learning from the donor”effects show that knowledge spillover can occur between spatially distant parties,which complements the literature.

关键词： China export knowledge spillover post-disaster aid

Operational requirements analysis method based on question answering of WEKG

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 Systems Engineering and Electronics 2024年第2期35卷 386-395页

作者： ZHANG Zhiwei DOU Yajie xu Xiangqian MA Yufeng JIANG Jiang tan Yuejin College of Systems Engineering National University of Defense TechnologyChangsha 410073China

The weapon and equipment operational requirement analysis(WEORA) is a necessary condition to win a future war,among which the acquisition of knowledge about weapons and equipment is a great challenge. The main challenge is that the existing weapons and equipment data fails to carry out structured knowledge representation, and knowledge navigation based on natural language cannot efficiently support the WEORA. To solve above problem, this research proposes a method based on question answering(QA) of weapons and equipment knowledge graph(WEKG) to construct and navigate the knowledge related to weapons and equipment in the WEORA. This method firstly constructs the WEKG, and builds a neutral network-based QA system over the WEKG by means of semantic parsing for knowledge navigation. Finally, the method is evaluated and a chatbot on the QA system is developed for the WEORA. Our proposed method has good performance in the accuracy and efficiency of searching target knowledge, and can well assist the WEORA.

关键词： operational requirement analysis weapons and equipment knowledge graph(WEKG) question answering(QA) neutral network

Data processing for the Active Particle-induced X-ray Spectrometer and initial scientific results from Chang'e-3 mission

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2014年第12期14卷 1595-1606页

作者： Xiao-Hui Fu Chun-Lai Li Guang-Liang Zhang Yong-Liao Zou Jian-Jun Liu Xin Ren xu tan Xiao-Xia Zhang Wei Zuo Wei-Bin Wen Wen-Xi Peng Xing-Zhu Cui Cheng-Mo Zhang Huan-Yu Wang National Astronomical Observatories Chinese Academy of Sciences Institute of High Energy Physics Chinese Academy of Sciences

The Active Particle-induced X-ray Spectrometer （APXS） is an important payload mounted on the Yutu rover, which is part of the Chang＇e-3 mission. The sci- entific objective of APXS is to perform in-situ analysis of the chemical composition of lunar soil and rock samples. The radioactive sources, 55Fe and 109Cd, decay and produce a-particles and X-rays. When X-rays and a-particles interact with atoms in the surface material, they knock electrons out of their orbits, which release energy by emitting X-rays that can be measured by a silicon drift detector （SDD）. The elements and their concentrations can be determined by analyzing their peak energies and in- tensities. APXS has analyzed both the calibration target and lunar soil once during the first lunar day and again during the second lunar day. The total detection time lasted about 266 min and more than 2000 frames of data records have been acquired. APXS has three operating modes： calibration mode, distance sensing mode and detection mode. In detection mode, work distance can be calculated from the X-ray counting rate collected by SDD. Correction for the effect of temperature has been performed to convert the channel number for each spectrum to X-ray energy. Dead time correction is used to eliminate the systematic error in quantifying the activity of an X-ray pulse in a sample and derive the real count rate. We report APXS data and initial results during the first and second lunar days for the Yutu rover. In this study, we analyze the data from the calibration target and lunar soil on the first lunar day. Seven major elements, including Mg, A1, Si, K, Ca, Ti and Fe, have been identified. Comparing the peak areas and ratios of calibration basalt and lunar soil the landing site was found to be depleted in K, and have lower Mg and A1 but higher Ca, Ti, and Fe. In the future, we will obtain the elemental concentrations of lunar soil at the Chang＇e-3 landing site using APXS data.

关键词： data analysis -- composition -- Moon