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New method to implement digital down converter in radar system

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Journal of Systems Engineering and Electronics 2005年第4期16卷 775-780页

作者： ma zhigang Wen Biyang Zhou Hao Bai Liyun Radio Propagation Lab Electronics and informations school Wuhan Univ. Wuhan 430079 P. R. China

Digital down converter （DDC） is the main part of the next generation high frequency （HF） radar. In order to realize the single chip integrations of digital receiver hardware in the next generation HF Radar, a new design for DDC by using FPGA is presented. Some important and practical applications are given in this paper, and the result can prove the validity. Because we can adjust the parameters freely according to our need, the DDC system can be adapted to the next generation HF radar system.

关键词： high frequency radar FPGA DDC decimation.

Fixed-Time Controller Design for a Quadrotor UAV with Asymmetric Output Error Constraints

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Journal of Systems Science & Complexity 2023年第5期36卷 1981-2000页

作者： WANG Fang ma zhigang ZHOU Chao ZHANG Zheng HUA Changchun ZONG Qun School of Science Yanshan UniversityQinhuangdao 066004China Ocean College Hebei Agricultural UniversityQinhuangdao 066003China School of Electric Engineering Yanshan UniversityQinhuangdao 066004China School of Electrical and Information Engineering Tianjin UniversityTianjin 300072China

In this article,a fixed-time tracking control strategy is proposed for a quadrotor UAV(QUAV)with external disturbance and asymmetric output error ***,a dynamic model of the QUAV is transformed into a strict feedback system with external disturbance,and it is decoupled into attitude subsystem and position subsystem for simplifying controller ***,an asymmetric tangent barrier Lyapunov function(ATBLF)is applied to solve the tracking error constraints problem,and a fixed-time control law is ***,a fixed-time disturbance observer(FTDO)is designed to cope with external ***,it is proved that the designed controller guarantees the tracking error remains within the constraint ranges and converges to zero in fixed-time by Lyapunov stability ***,the effectiveness of the proposed control scheme is verified by numerical simulations.

关键词： Asymmetric tangent barrier Lyapunov function(ATBLF) fixed-time disturbance observer(FTDO) output error constraints quadrotor UAV(QUAV)

Anti-interference method for HF radars by transmitting phase-modulated chirps

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High Technology Letters 2006年第4期12卷 392-396页

作者：周浩 Wen Biyang ma zhigang Wu Shicai School of Electronic Information Wuhan University Wuhan 430079 P.R. China Southwest China Re.arch Institute of Electronic Equipment Chengdu 610036 P R China

Radio frequency interference （RFI） is a major problem in high-frequency （HF） radars. Conventional filtering-involved RFI suppression methods may introduce distortions to the target signals of interest and often demand extra hardware costs. In this paper, a novel method for RFI suppression by using linearly or randomly phase-modulated （PM） chirps is proposed, which enables independent analyses of the target signal and the RFI. Furthermore, the directions of arrival （DOA） of the interference are used as constraints to ensure a better DOA estimation of the target. The effectiveness of the method is demonstrated by numerical simulation results. The method can greatly improve the anti-interference capabilities of HF radars and is extremely applicable in the portable and low-cost radar systems.

关键词： HF radar radio frequency interference phase modulation direction of amval MUSIC

Ladder-type Diindenopyrazine Based Conjugated Copolymers for Organic Solar Cells with High Open-circuit Voltages

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Chinese Journal of Chemistry 2013年第11期31卷 1409-1417页

作者： Shanci Chen Changquan Tang zhigang Yin Yunlong ma Dongdong Cai Dhanavel Ganeshan Qingdong Zheng State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences Fuzhou Fujian 350002 China

A ladder-type diindenopyrazine （IPY） was synthesized and used as a building block for constructing conjugated copolymers. Three copolymers based on the IPY moiety were obtained via the Suzuki coupling reaction with dif- ferent monomers, including 4,7-dithien-2-yl-2,1,3-benzothiadiazole （DBT）, 5,8-dithien-2-yl-2,3-diphenylquinoxa- line （DTQ）, and 5,8-dithien-2-yl-2,3-di（4-fluorophenyl）quinoxaline （DFTQ）. The obtained polymers were charac- terized by 1H NMR spectroscopy, UV-Vis absorption spectroscopy, cyclic voltammetry, and gel permeation chro- matography （GPC）. Owing to the four solubilizing alkyl chains on the IPY unit, all the three copolymers have good solubility in common solvents. These polymers have deep-lying HOMO energy levels in the range of-5.55-5.60 eV, and exhibit field-effect mobilities as high as 0.006 cm2.V-l.s i. Photovoltaic applications of these polymers as light-harvesting and hole-conducting materials were investigated in conjunction with [6,6]-phenyl-C6rbutyric acid methyl ester （PC61BM）. Both conventional and inverted devices were fabricated based on these three polymers. A power conversion efficiency （PCE） of 2.53% and a high open-circuit voltage of 1.00 V were obtained under simu- lated solar light AM 1.5 G （100 mW/cm2） from an inverted solar cell with an active layer containing 25 wt% lad- der-type IPY containing copolymer （PIPYDTQ） and 75 wt% PC61BM. Moreover, a high open-circuit voltage of 1.02 V and a PCE of 2.40% were achieved from a conventional solar cell based on PIPYDTQ.

关键词： conjugated polymers diindenopyrazine organic solar cells field-effect transistors open-circuit volt-age

Impact Factors on Distribution and Characteristics of Natural Plant Community in Reclamation Zones of Changjiang River Estuary

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Chinese Geographical Science 2012年第2期22卷 154-166页

作者： SUN Yongguang LI Xiuzhen HE Yanlong JIA Yue ma zhigang GUO Wenyong XIN Zaijun State Key Laboratory of Estuarine and Coastal Research East China Normal University Shanghai 200062 China Department of History Culture and Tourism Gannan Normal University Ganzhou 341000 China

To identify impact factors on the distribution and characters of natural plants community in reclamation area, with survey data from 67 plant quadrats in July 2009, soil properties data from 216 sampling points in April 2009, and TM (30 m) data in 2006, the composition and characteristics of natural plants community in different time of the Fengxian area in the Changjiang (Yangtze) River estuary were analyzed with two-way indicator species analysis (TWINSPAN), multivariate analysis of variance (maNOVA), detrended canonical correspondence analysis (DCCA) and canonical correspondence analysis (CCA). The results show that: 1) The plant communities in the reclaimed area are mainly mesophytes and helophytic-mesophytic transitional communities, showing a gradient distribution trend with the change in reclamation years. Species richness (ma), species diversity (H) and above-ground biomass also increase with the increase of reclamation years. Nevertheless, they appear to decline slightly in the middle and late reclamation period (> 30 years). 2) With the rise in land use levels, the changes in species richness and species diversity tend to increase at first and then decrease; species dominance (D), however, tends to decline; and above-ground biomass increases slightly. 3) The distribution of the plant community is mainly influenced by the following factors: land use levels (R = 0.55, p mation time (R = 0.40, p < 0.05).

关键词： natural plant communities soil properties land use patterns reclamation time Changjiang River estuary

The influences of biotic and abiotic factors on the occurrence and severity of poplar canker disease in Qingfeng County, China and the management implications

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Journal of Forestry Research 2015年第4期26卷 1025-1034页

作者： zhigang ma Jingle Zhu Zhiqiang Sun Jun Liang Zhaoxin Zhang Limin Zhang Lijuan Sun Wenjuan Li Paulownia R&D Center of China Chinese Academy of Forestry Non-timber Forestry R&D Center Chinese Academy of Forestry The Key Laboratory of Forest Protection of China State Forestry Administration Research Institute of Forest EcologyEnvironment and ProtectionChinese Academy of Forestry Puyang Forest Research Institute

Landscape pathology is a research approach that can provide validation of the effectiveness of regional controls of forest disease at a landscape scale. In this paper, we analyzed the effects of stand features, management approaches, and geographical locations on poplar canker disease incidence （DI） and disease severity index （DSI） of individual trees at a 10 km x 10 km mesoscale landscape in Qingfeng County, China. DI varied significantly with stand age, tree densities, and the degree of canopy closure. DI in stands younger than 4 years old was significantly lower than that in the stands over 6 years old and reached the highest value at a stand age of 8-10 years. Overall, DI was positively correlated with stand age, stand density, andthe degree of canopy closure. DI was significantly lower in agro-forest stand patches than in other three patch types, i.e. isolated patch, pure stand patch, and mixed stand patch. Poplar plantations distributed around and near to villages exhibited significantly higher DI mainly due to human activities and herbivores. Fragmentation or connectivity in this mesoscale landscape seemed not impact disease occurrence. DSI was not significantly correlated with stand density, but varied significantly with tree varieties and trees ages. DSI was highest in stands of 10-12 year trees for all poplar varieties we studied here. Plantation density and plantation age were thus critical factors in determining DI and DSI. A logistic predictive model of disease occurrence was developed for the study area, considering varieties, age, height, density, canopy cover, stand types, patch types, management status, and stand geographical locations. Our study here shows that adjustment of stand density by thinning at different plantation ages is an effective approach controlling the occurrence canker disease in short-rotation poplar plantations at the landscape scale.

关键词： Landscape pathology Poplar plantation Canker disease - Disease incidence - Disease severityincidence - Stand features Adaptation

Effect of Reclamation Time and Land Use on Soil Properties in Changjiang River Estuary,China

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Chinese Geographical Science 2011年第4期21卷 403-416页

作者： SUN Yongguang LI Xiuzhen ülo maNDER HE Yanlong JIA Yue ma zhigang GUO Wenyong XIN Zaijun State Key Laboratory of Estuarine and Coastal Research East China Normal UniversityShanghai 200062China National marine Environment Monitor Center Dalian 116023China Department of Geography Institute of Ecology & Earth SciencesUniversity of Tartu46 Vanemuise St.Tartu51014Estonia

The objective of this study is to analyze soil physical and chemical properties,soil comprehensive functions and impact factors after different years of *** on the survey data taken from 216 soil sampling points in the Fengxian Reclamation Area of the Changjiang (Yangtze) River Estuary,China in April 2009 and remotely sensed TM data in 2006,while by virtue of multivariate analysis of variance (maNOVA),geo-statistical analysis (GA),prin-cipal component analysis (PCA) and canonical correspondence analysis (CCA),it was concluded that:1) With the in-crease in reclamation time,soil moisture,soil salinity,soil electric conductivity and soil particle size tended to decline,yet soil organic matter tended to *** available phosphorous tended to increase in the early reclamation period,yet it tended to decline after about 49 years of *** nitrate nitrogen,soil ammonia nitrogen and pH changed slightly in different reclamation *** physical and chemical properties reached a steady state after about 30 years of reclamation.2) According to the results of PCA analysis,the weighted value (0.97 in total) that represents soil nutrient factors (soil nitrate nitrogen,soil organic matter,soil available phosphorous,soil ammonia nitrogen,pH and soil particle size) were higher than the weighted value (0.48 in total) of soil limiting factors (soil salinity,soil elec-tric conductivity and soil moisture).The higher the F value is,the better the soil quality is.3) Different land use types play different roles in the soil function maturity process,with farmlands providing the best contribution.4) Soil physi-cal and chemical properties in the reclamation area were mainly influenced by reclamation time,and then by land use *** correlation (0.1905) of the composite index of soil function (F) with reclamation time was greater than that with land use types (-0.1161).

关键词： soil properties land use types reclamation time soil function Changjiang River Estuary

Design and Implementation of the Employment management Decision Support System based on machine Learning

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Journal of Electronic Research and Application 2024年第5期8卷 134-140页

作者： zhigang ma Zhengzhou University of Science and Technology Zhengzhou 450064Henan ProvinceChina

To address the challenges of current college student employment management,this study designed and implemented a machine learning-based decision support system for college student employment *** system collects and analyzes multidimensional data,uses machine learning algorithms for prediction and matching,provides personalized employment guidance for students,and provides decision support for universities and *** research results indicate that the system can effectively improve the efficiency and accuracy of employment guidance,promote school-enterprise cooperation,and achieve a win-win situation for all parties.

关键词： machine learning Employment of college students Decision support system Data analysis

Experimental and Simulated Study on the Cylinder Deactivation of Vehicle Gasoline Engine 1

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