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Winter wheat yield improvement by genetic gain across different provinces in China 被引量:1
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作者 Wei Chen Jingjuan Zhang Xiping Deng 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2024年第2期468-483,共16页
The replacement of winter wheat varieties has contributed significantly to yield improvement worldwide,with remarkable progress in China.Drawing on two sets of data,production yield from the National Bureau of Statist... The replacement of winter wheat varieties has contributed significantly to yield improvement worldwide,with remarkable progress in China.Drawing on two sets of data,production yield from the National Bureau of Statistics of China and experimental yield from literature,this study aims to(1)illustrate the increasing patterns of production yield among different provinces from 1978 to 2018 in China,(2)explore the genetic gain in yield and yield relevant traits through the variety replacement based on experimental yield from 1937 to 2016 in China,and(3)compare the yield gap between experimental yield and production yield.The results show that both the production and experimental yields significantly increased along with the variety replacement.The national annual yield increase ratio for the production yield was 1.67%from 1978 to 2018,varying from 0.96%in Sichuan Province to 2.78%in Hebei Province;such ratio for the experimental yield was 1.13%from 1937 to 2016.The yield gap between experimental and production yields decreased from the 1970s to the 2010s.This study reveals significant increases in some yield components consequent to variety replacement,including thousand-grain weight,kernel number per spike,and grain number per square meter;however,no change is shown in spike number per square meter.The biomass and harvest index consistently and significantly increased,whereas the plant height decreased significantly. 展开更多
关键词 genetic gain winter wheat YIELD yield components
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Preweaning period is a critical window for rumen microbial regulation of average daily gain in Holstein heifer calves
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作者 Shengyang Xu Chong Jiao +1 位作者 Qiyu Diao Yan Tu 《Journal of Animal Science and Biotechnology》 SCIE CAS CSCD 2024年第1期396-411,共16页
Background Rumen bacterial groups can affect growth performance,such as average daily gain(ADG),feed intake,and efficiency.The study aimed to investigate the inter-relationship of rumen bacterial composition,rumen fer... Background Rumen bacterial groups can affect growth performance,such as average daily gain(ADG),feed intake,and efficiency.The study aimed to investigate the inter-relationship of rumen bacterial composition,rumen fermentation indicators,serum indicators,and growth performance of Holstein heifer calves with different ADG.Twelve calves were chosen from a trail with 60 calves and divided into higher ADG(HADG,high pre-and post-weaning ADG,n=6)and lower ADG(LADG,low pre-and post-weaning ADG,n=6)groups to investigate differences in bacterial composition and functions and host phenotype.Results During the preweaning period,the relative abundances of propionate producers,including g_norank_f_Butyricicoccaceae,g_Pyramidobacter,and g_norank_f_norank_o_Clostridia_vadin BB60_group,were higher in HADG calves(LDA>2,P<0.05).Enrichment of these bacteria resulted in increased levels of propionate,a gluconeogenic precursor,in preweaning HADG calves(adjusted P<0.05),which consequently raised serum glucose concentrations(adjusted P<0.05).In contrast,the relative abundances of rumen bacteria in post-weaning HADG calves did not exert this effect.Moreover,no significant differences were observed in rumen fermentation parameters and serum indices between the two groups.Conclusions The findings of this study revealed that the preweaning period is the window of opportunity for rumen bacteria to regulate the ADG of calves. 展开更多
关键词 Average daily gain CALVES Preweaning period Rumen microbiota
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Topological laser on square lattice with gain–loss-induced higher-order corner modes
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作者 廖明杰 韦梅松 +2 位作者 王帅领 许静平 羊亚平 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第6期189-195,共7页
We investigate the higher-order topological laser in the two-dimensional(2D) coupled-cavity array. By adding staggered on-site gain and loss to the 2D Hermitian array with a trivial phase, the system will emerge degen... We investigate the higher-order topological laser in the two-dimensional(2D) coupled-cavity array. By adding staggered on-site gain and loss to the 2D Hermitian array with a trivial phase, the system will emerge degenerate topological corner modes, which are protected by bulk band gap. For such a non-Hermitian model, by adjusting the parameters of the system and introducing the pumping into the cavity at the corner, a single-mode lasing with topological protection emerges.Furthermore, single-mode lasing exists over a wide range of pumping strengths. No matter where the cavity is initially stimulated, after enough time evolution, all the cavities belonging to the topological corner mode can emit a stable laser. 展开更多
关键词 topological corner modes nonlinear saturated gain single-mode lasing
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A Stroke-Limitation AMD Control System with Variable Gain and Limited Area for High-Rise Buildings
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作者 Zuo-Hua Li Qing-Gui Wu +1 位作者 Jun Teng Chao-Jun Chen 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第1期865-884,共20页
Collisions between a moving mass and an anti-collision device increase structural responses and threaten structural safety.An active mass damper(AMD)with stroke limitations is often used to avoid collisions.However,a ... Collisions between a moving mass and an anti-collision device increase structural responses and threaten structural safety.An active mass damper(AMD)with stroke limitations is often used to avoid collisions.However,a strokelimited AMD control system with a fixed limited area shortens the available AMD stroke and leads to significant control power.To solve this problem,the design approach with variable gain and limited area(VGLA)is proposed in this study.First,the boundary of variable-limited areas is calculated based on the real-time status of the moving mass.The variable gain(VG)expression at the variable limited area is deduced by considering the saturation of AMD stroke.Then,numerical simulations of a stroke-limited AMD control system with VGLA are conducted on a high-rise building structure.These numerical simulations show that the proposed approach has superior strokelimitation performance compared with a stroke-limited AMD control system with a fixed limited area.Finally,the proposed approach is validated through experiments on a four-story steel frame. 展开更多
关键词 High-rise buildings active control stroke limitations variable gain variable limited area
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ANovel Non-Isolated Cubic DC-DC Converter with High Voltage Gain for Renewable Energy Power Generation System
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作者 Qin Yao Yida Zeng Qingui Jia 《Energy Engineering》 EI 2024年第1期221-241,共21页
In recent years,switched inductor(SL)technology,switched capacitor(SC)technology,and switched inductor-capacitor(SL-SC)technology have been widely applied to optimize and improve DC-DC boost converters,which can effec... In recent years,switched inductor(SL)technology,switched capacitor(SC)technology,and switched inductor-capacitor(SL-SC)technology have been widely applied to optimize and improve DC-DC boost converters,which can effectively enhance voltage gain and reduce device stress.To address the issue of low output voltage in current renewable energy power generation systems,this study proposes a novel non-isolated cubic high-gain DC-DC converter based on the traditional quadratic DC-DC boost converter by incorporating a SC and a SL-SC unit.Firstly,the proposed converter’s details are elaborated,including its topology structure,operating mode,voltage gain,device stress,and power loss.Subsequently,a comparative analysis is conducted on the voltage gain and device stress between the proposed converter and other high-gain converters.Then,a closed-loop simulation system is constructed to obtain simulation waveforms of various devices and explore the dynamic performance.Finally,an experimental prototype is built,experimental waveforms are obtained,and the experimental dynamic performance and conversion efficiency are analyzed.The theoretical analysis’s correctness is verified through simulation and experimental results.The proposed converter has advantages such as high voltage gain,low device stress,high conversion efficiency,simple control,and wide input voltage range,achieving a good balance between voltage gain,device stress,and power loss.The proposed converter is well-suited for renewable energy systems and holds theoretical significance and practical value in renewable energy applications.It provides an effective solution to the issue of low output voltage in renewable energy power generation systems. 展开更多
关键词 Cubic DC-DC converter high voltage gain low device stress high efficiency renewable energy
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Design of a Low Power Low-Noise Amplifier with Improved Gain/Noise Ratio
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作者 Raja Mahmou Khalid Faitah 《World Journal of Engineering and Technology》 2024年第1期80-91,共12页
This work details the development of a broad-spectrum LNA (Low Noise Amplifier) circuit using a 65 nm CMOS technology. The design incorporates an inductive degeneracy circuit, employing a theoretical approach to enhan... This work details the development of a broad-spectrum LNA (Low Noise Amplifier) circuit using a 65 nm CMOS technology. The design incorporates an inductive degeneracy circuit, employing a theoretical approach to enhance gain, minimize noise levels, and uphold low power consumption. The progression includes a shift to a cascode structure to further refine LNA parameters. Ultimately, with a 1.8 V bias, the achieved performance showcases a gain-to-noise figure ratio of 16 dB/0.5 dB, an IIP3 linearity at 5.1 dBm, and a power consumption of 3 mW. This architecture is adept at operating across a wide frequency band spanning from 0.5 GHz to 6 GHz, rendering it applicable in diverse RF scenarios. 展开更多
关键词 LNA DEGENERACY Noise Figure LINEARITY Power Consumption gain
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Analysis of the Effects of Maternal Body Mass Index and Gestational Weight Gain on Maternal and Neonatal Outcomes in Twin Pregnancy
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作者 Fanhua Shi Yuanyuan Li 《Journal of Clinical and Nursing Research》 2024年第3期127-133,共7页
Objective:To investigate the effects of maternal body mass index(BMI)and gestational weight gain on maternal and neonatal outcomes in twin pregnancies.Methods:Five hundred cases of twin pregnancies were divided into a... Objective:To investigate the effects of maternal body mass index(BMI)and gestational weight gain on maternal and neonatal outcomes in twin pregnancies.Methods:Five hundred cases of twin pregnancies were divided into a low body weight group(68 cases),a normal weight group(355 cases),an overweight group(65 cases),and an obesity group(12 cases)according to the World Health Organization(WHO)Body Mass Index(BMI)classification guidelines Results:Comparison of weight gain during different pregnancies revealed that pregnant women were mainly of low weight and average weight.The higher the BMI before pregnancy,the higher the incidence of excessive weight gain during pregnancy.The incidences of gestational diabetes mellitus(GDM)and premature rupture of membranes in women with low weight gain were significantly higher than those in women with average weight gain and high weight gain(P<0.05).The incidences of gestational hypertension,preeclampsia,and anemia in women with high weight gain were significantly higher than those in women with low weight gain and average weight gain(P<0.05).The incidence of neonatal birth weight,fetal distress,and macrosomia in the high weight gain group was significantly higher than those in the low weight gain and average weight gain groups(P<0.05).The birth weight of newborns in low-weight gain mothers was significantly lower than that of normal-weight gain mothers(P<0.05).Conclusion:Poor maternal and infant outcomes were common in women with insufficient or excessive weight gain during pregnancy.Therefore,for women with twin pregnancies,weight management is crucial to ensure maternal and infant health. 展开更多
关键词 Body mass index Weight gain Pregnancy outcome
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Genetic gain and inbreeding from simulation of different genomic mating schemes for pig improvement 被引量:1
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作者 Fuping Zhao Pengfei Zhang +4 位作者 Xiaoqing Wang Deniz Akdemir Dorian Garrick Jun He Lixian Wang 《Journal of Animal Science and Biotechnology》 SCIE CAS CSCD 2023年第4期1363-1376,共14页
Background Genomic selection involves choosing as parents those elite individuals with the higher genomic estimated breeding values(GEBV)to accelerate the speed of genetic improvement in domestic animals.But after mul... Background Genomic selection involves choosing as parents those elite individuals with the higher genomic estimated breeding values(GEBV)to accelerate the speed of genetic improvement in domestic animals.But after multi-generation selection,the rate of inbreeding and the occurrence of homozygous harmful alleles might increase,which would reduce performance and genetic diversity.To mitigate the above problems,we can utilize genomic mating(GM)based upon optimal mate allocation to construct the best genotypic combinations in the next generation.In this study,we used stochastic simulation to investigate the impact of various factors on the efficiencies of GM to optimize pairing combinations after genomic selection of candidates in a pig population.These factors included:the algorithm used to derive inbreeding coefficients;the trait heritability(0.1,0.3 or 0.5);the kind of GM scheme(focused average GEBV or inbreeding);the approach for computing the genomic relationship matrix(by SNP or runs of homozygosity(ROH)).The outcomes were compared to three traditional mating schemes(random,positive assortative or negative assortative matings).In addition,the performance of the GM approach was tested on real datasets obtained from a Large White pig breeding population.Results Genomic mating outperforms other approaches in limiting the inbreeding accumulation for the same expected genetic gain.The use of ROH-based genealogical relatedness in GM achieved faster genetic gains than using relatedness based on individual SNPs.The GROH-based GM schemes with the maximum genetic gain resulted in 0.9%-2.6%higher rates of genetic gainΔG,and 13%-83.3%lowerΔF than positive assortative mating regardless of heritability.The rates of inbreeding were always the fastest with positive assortative mating.Results from a purebred Large White pig population,confirmed that GM with ROH-based GRM was more efficient than traditional mating schemes.Conclusion Compared with traditional mating schemes,genomic mating can not only achieve sustainable genetic progress but also effectively control the rates of inbreeding accumulation in the population.Our findings demonstrated that breeders should consider using genomic mating for genetic improvement of pigs. 展开更多
关键词 Genetic gain Genomic mating Genomic selection INBREEDING PIG
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嗜吞噬无形体效应蛋白Ats-1调控宿主细胞剪接体转录机制的初步分析
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作者 李芮芮 史梦华 +5 位作者 张妍 何洪琴 王雨璐 陈佳 王勇 陈创夫 《中国预防兽医学报》 CAS CSCD 北大核心 2024年第1期39-48,共10页
为研究嗜吞噬无形体效应蛋白Ats-1对宿主细胞内蛋白表达的影响,并初步分析Ats-1对宿主细胞剪接体的调控机制,本研究将嗜吞噬无形体的Ats-1基因克隆后连接至pcDNA3.1质粒,构建pcDNA3.1-Ats-1重组质粒,经PCR和测序鉴定正确后利用脂质体Lip... 为研究嗜吞噬无形体效应蛋白Ats-1对宿主细胞内蛋白表达的影响,并初步分析Ats-1对宿主细胞剪接体的调控机制,本研究将嗜吞噬无形体的Ats-1基因克隆后连接至pcDNA3.1质粒,构建pcDNA3.1-Ats-1重组质粒,经PCR和测序鉴定正确后利用脂质体LipofectamineTM3000将其转染HEK293T细胞,继续培养至24 h、48 h时经western blot鉴定,结果显示,在48 ku(全长蛋白)和35 ku(成熟蛋白)出现特异性条带,表明Ats-1蛋白在细胞内可正确表达;且相较于24 h,48 h Ats-1蛋白在细胞内的表达量显著增加(P<0.05)。将重组质粒pcDNA3.1-Ats-1和空质粒pcDNA3.1分别转染HEK293T细胞,48 h后收获细胞并裂解取裂解液,利用同量异位标签定量蛋白质组学方法(iTRAQ)筛选Ats-1表达后宿主细胞内差异显著表达的蛋白,并采用基因本体论(GO)分析差异显著表达蛋白的功能,利用京都基因与基因组百科全书(KEGG)数据库分析差异显著表达蛋白参与的信号通路。从剪接体通路选取34个差异表达蛋白通过q RT-PCR验证。i TRAQ结果显示,与空质粒转染细胞组相比,重组质粒pcDNA3.1-Ats-1转染细胞组共鉴定到852个差异显著表达的蛋白,其中表达显著上调蛋白406个,表达显著下调蛋白446个。GO功能分析结果显示,差异显著表达蛋白主要定位在膜、胞内膜结合细胞器、膜组分,参与大分子生物合成过程,有核酸和RNA结合活性。KEGG信号通路分析结果显示,差异显著表达蛋白显著富集于剪接体、N-糖基化、蛋白输出和RNA运输等信号通路。q RT-PCR结果显示,剪接体通路富集的差异显著表达蛋白仅O43143蛋白的m RNA转录水平上调,其他33个蛋白(A0A024R1K8、Q13435、Q13573等)m RNA的转录水平均显著下调,与iTRAQ的分析结果一致。综上所述,本研究首次证实Ats-1蛋白表达后可能参与宿主细胞中剪接体、N-糖基化和蛋白输出信号通路的调控,抑制宿主细胞中剪接体调控通路中部分蛋白的转录,从而可能抑制剪接体调控,该结果为研究嗜吞噬无形体效应蛋白Ats-1在宿主细胞中的调控机制提供了新的方向和思路。 展开更多
关键词 ats-1蛋白 ITRAQ 差异表达蛋白 剪接体
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Intoxication Induced by Urea Containing Diets in Broiler Chickens: Effect on Weight Gain, Feed Conversion Ratio, Hematological and Biochemical Profiles
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作者 Mohammed Al-Zharani Mohammed Mubarak +2 位作者 Hassan Ahmed Rudayni Mahmoud M. Abdelwahab Mohammed Al-Eissa 《Advances in Bioscience and Biotechnology》 CAS 2023年第3期106-119,共14页
Urea as a source of cheap non-protein nitrogen is used to adulterate fish and meat meals which are basic components of broiler diets. The present study was carried out to elucidate the effects of urea on weight gain, ... Urea as a source of cheap non-protein nitrogen is used to adulterate fish and meat meals which are basic components of broiler diets. The present study was carried out to elucidate the effects of urea on weight gain, and hematological and biochemical profiles. A total of 48 broiler chicks were randomly allotted into 4 groups, designated Groups 1, 2, 3 and 4 of 12 birds each. Birds in Groups 2, 3 and 4 were fed on diets containing urea at the levels of 1%, 2.5% and 4%, respectively. Birds in Group 1 served as control and were not exposed to urea. Experimentation period was for 3 weeks and experiment was terminated when birds were 42 days of age. Body weight of all intoxicated birds at the various intervals was significantly decreased in comparison with that of the untreated control. Compared with control, all intoxicated broilers manifested significant (P ≤ 0.05) decrease in all hematological parameters involving erythrocytic and total leucocytic counts, Hemoglobin (Hb) and Packed Cell Volume (PCV) on a dose- and time-pattern. In comparison with the control levels, biochemical profile of the intoxicated birds disclosed significant decrease in blood glucose level and significant increase in serum uric acid, urea, Alkaline Phosphatase (ALP) and Lactate Dehydrogenase (LDH) levels. Based upon the present data, it was concluded that the addition of urea to broiler diets bears serious sequences concerning the general health condition, performance, weight gain, and hematological and biochemical profiles. 展开更多
关键词 UREA INTOXICatION Broiler Chickens Weight gain Feed Conversion Ratio
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Thermo-hydro-mechanical (THM) coupled simulation of the land subsidence due to aquifer thermal energy storage (ATES) system in soft soils 被引量:1
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作者 Yang Wang Fengshou Zhang Fang Liu 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第6期1952-1966,共15页
Aquifer thermal energy storage(ATES)system has received attention for heating or cooling buildings.However,it is well known that land subsidence becomes a major environmental concern for ATES projects.Yet,the effect o... Aquifer thermal energy storage(ATES)system has received attention for heating or cooling buildings.However,it is well known that land subsidence becomes a major environmental concern for ATES projects.Yet,the effect of temperature on land subsidence has received practically no attention in the past.This paper presents a thermo-hydro-mechanical(THM)coupled numerical study on an ATES system in Shanghai,China.Four water wells were installed for seasonal heating and cooling of an agriculture greenhouse.The target aquifer at a depth of 74e104.5 m consisted of alternating layers of sand and silty sand and was covered with clay.Groundwater level,temperature,and land subsidence data from 2015 to 2017 were collected using field monitoring instruments.Constrained by data,we constructed a field scale three-dimensional(3D)model using TOUGH(Transport of Unsaturated Groundwater and Heat)and FLAC3D(Fast Lagrangian Analysis of Continua)equipped with a thermo-elastoplastic constitutive model.The effectiveness of the numerical model was validated by field data.The model was used to reproduce groundwater flow,heat transfer,and mechanical responses in porous media over three years and capture the thermo-and pressure-induced land subsidence.The results show that the maximum thermoinduced land subsidence accounts for about 60%of the total subsidence.The thermo-induced subsidence is slightly greater in winter than that in summer,and more pronounced near the cold well area than the hot well area.This study provides some valuable guidelines for controlling land subsidence caused by ATES systems installed in soft soils. 展开更多
关键词 Aquifer thermal energy storage(atES) Land subsidence TOUGH-FLAC3D Thermo-elastoplastic constitutive model
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Fixed-Time Stabilization of a Class of Strict-Feedback Nonlinear Systems via Dynamic Gain Feedback Control
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作者 Chenghui Zhang Le Chang +1 位作者 Lantao Xing Xianfu Zhang 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2023年第2期403-410,共8页
This paper presents a novel fixed-time stabilization control(FSC)method for a class of strict-feedback nonlinear systems involving unmodelled system dynamics.The key feature of the proposed method is the design of two... This paper presents a novel fixed-time stabilization control(FSC)method for a class of strict-feedback nonlinear systems involving unmodelled system dynamics.The key feature of the proposed method is the design of two dynamic parameters.Specifically,a set of auxiliary variables is first introduced through state transformation.These variables combine the original system states and the two introduced dynamic parameters,facilitating the closed-loop system stability analyses.Then,the two dynamic parameters are delicately designed by utilizing the Lyapunov method,ensuring that all the closed-loop system states are globally fixed-time stable.Compared with existing results,the“explosion of complexity”problem of backstepping control is avoided.Moreover,the two designed dynamic parameters are dependent on system states rather than a time-varying function,thus the proposed controller is still valid beyond the given fixedtime convergence instant.The effectiveness of the proposed method is demonstrated through two practical systems. 展开更多
关键词 Dynamic gain feedback control fixed-time stabilization strict-feedback nonlinear system
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High gain and circularly polarized substrate integrated waveguide cavity antenna array based on metasurface
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作者 白昊 王光明 邹晓鋆 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第1期298-304,共7页
Two substrate integrated waveguide(SIW) cavity antenna arrays based on metasurface are proposed in this paper. By rotating the metasurface element, circularly polarized and high gain antennas are achieved respectively... Two substrate integrated waveguide(SIW) cavity antenna arrays based on metasurface are proposed in this paper. By rotating the metasurface element, circularly polarized and high gain antennas are achieved respectively. Firstly, multi-mode resonance theory is employed to broaden the bandwidth of the slot antenna. And then, an SIW cavity composed of 4×4 cornercut elements is added on the top of the slot antenna to achieve the circular polarization and improve the front-to-back ratio. Thirdly, the metasurface elements are sequentially rotated and a high gain antenna with 2-dBi enhancement on average in the operation band is obtained. Based on the two antenna units, two 2×2 antenna arrays are designed. The circularly polarized and high gain antenna arrays are both fabricated to verify the correctness. Furthermore, the novel wideband phase shifter is employed in the circularly polarized antenna to obtain an operating bandwidth of 38%(4.05 GHz–5.95 GHz)and AR bandwidth of 24.9%(4.4 GHz–5.65 GHz). The bandwidth of the high gain antenna can reach 42.7%(3.95 GHz–6.1 GHz) and with the gain enhancement of 2 dBi compared with that of the circularly polarized antenna. The gain remains steady in most of operating band within a variation of 1 dBi. It is remarkable that the rotating of the metasurface element has a great influence on the antenna performance, which provides a new explication for the multi-function antenna design. 展开更多
关键词 substrate integrated waveguide(SIW) cavity antenna metasurface high gain circularly polarized
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Design of a High-Gain 2 × 1 Array Antenna for S-Band Applications
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作者 Md. Imran Hossain Md. Ariful Islam +1 位作者 Md. Tofail Ahmed Md. Humaun Kabir 《World Journal of Engineering and Technology》 2023年第2期293-302,共10页
Antennas are an indispensable element in wireless networks. For long-distance wireless communication, antenna gains need to be very strong (highly directive) because the signal from the antenna loses a lot of str... Antennas are an indispensable element in wireless networks. For long-distance wireless communication, antenna gains need to be very strong (highly directive) because the signal from the antenna loses a lot of strength as it travels over long distances. This is true in the military with missile, radar, and satellite systems, etc. Antenna arrays are commonly employed to focus electromagnetic waves in a certain direction that cannot be achieved perfectly with a single-element antenna. The goal of this study is to design a rectangular microstrip high-gain 2 × 1 array antenna using ADS Momentum. This microstrip patch array design makes use of the RT-DUROID 5880 as a substrate with a dielectric constant of 2.2, substrate height of 1.588 mm, and tangent loss of 0.001. To achieve efficient gain and return loss characteristics for the proposed array antenna, RT-Duroid is a good choice of dielectric material. The designed array antenna is made up of two rectangular patches, which have a resonance frequency of 3.3 GHz. These rectangular patches are excited by microstrip feed lines with 13 mm lengths and 4.8 mm widths. The impedance of the patches is perfectly matched by these transmission lines, which helps to get better antenna characteristics. At a resonance frequency of 3.3 GHz, the suggested antenna array has a directivity of 10.50 dB and a maximum gain of 9.90 dB in the S-band. The S parameters, 3D radiation pattern, directivity, gain, and efficiency of the constructed array antenna are all available in ADS Momentum. 展开更多
关键词 Microstrip Patch Antenna Array Antenna Microstrip Feed Rectangular Patch gain Efficiency DIRECTIVITY ADS
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基于身份的R-ate对聚合签名方案
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作者 敖凌峰 刘星江 +2 位作者 王慧 王辉 刘瑶 《通信技术》 2024年第5期506-511,共6页
聚合签名是一种密码学技术,其核心思想在于将多个签名者的签名结果聚合成一个新的签名,让多方签署者以群体的形式生成数字签名,以提高签名及签名验证的效率。通过改进Gentry和Ramzan等人的方案,提出了两种基于身份的R-ate对聚合签名方案... 聚合签名是一种密码学技术,其核心思想在于将多个签名者的签名结果聚合成一个新的签名,让多方签署者以群体的形式生成数字签名,以提高签名及签名验证的效率。通过改进Gentry和Ramzan等人的方案,提出了两种基于身份的R-ate对聚合签名方案,分别适用于对相同消息和不同消息的签名值生成、聚合和验证。新的聚合签名方案签名值长度适中,签名值生成及验证过程时间合理,其中签名过程主要涉及两次点乘运算,验证过程主要涉及3次R-ate配对运算。 展开更多
关键词 基于身份 R-ate配对 BN曲线 聚合签名
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Mechanisms Influencing Learning Gains Under Information Security: Structural Equation Modeling with Mediating Effect
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作者 Teng Zong Fengsi Wang +1 位作者 Xin Wei Yibo Liu 《Intelligent Automation & Soft Computing》 SCIE 2023年第6期3447-3468,共22页
With the expanding enrollments in higher education,the quality of col-lege education and the learning gains of students have attracted much attention.It is important to study the influencing factors and mechanisms of ... With the expanding enrollments in higher education,the quality of col-lege education and the learning gains of students have attracted much attention.It is important to study the influencing factors and mechanisms of individual stu-dents’acquisition of learning gains to improve the quality of talent cultivation in colleges.However,in the context of information security,the original data of learning situation surveys in various universities involve the security of educa-tional evaluation data and daily privacy of teachers and students.To protect the original data,data feature mining and correlation analyses were performed at the model level.This study selected 12,181 pieces of data from X University,which participated in the Chinese College Student Survey(CCSS)from 2018 to 2021.A confirmatory factor analysis was conducted and a structural equation modeling was conducted using AMOS 24.0.Through hypothesis testing,this study explored the mechanisms that influence learning gains from the per-spectives of student involvement,teacher involvement,and school support.The results indicated that the quality of student involvement has an important mediat-ing effect on learning gains and that a supportive campus environment has the greatest influence on learning gains.Establishing positive emotional communica-tions between teachers and students is a more direct and effective method than improving the teaching level to improve the quality of student involvement.This study discusses the implications of these results on the research and practice of connotative development in higher education. 展开更多
关键词 Structural equation model mediating effect chinese college student survey learning gains
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Nonlinear Absorption and Low-threshold Two-photon Pumped Amplified Stimulated Emission from FAPbBr_(3) Nanocrystals
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作者 WANG Yajuan TAY Yong Kang Eugene +3 位作者 WANG Fang YU Sheng SUM Tze Chien LIU Wei 《发光学报》 EI CAS CSCD 北大核心 2024年第8期1281-1291,共11页
Formamidinium lead bromide(FAPbBr_(3))nanocrystals(NCs)have been considered to be a good optoelectronic material due to their pure green emission,excellent stability and superior carrier transport characteristics.Howe... Formamidinium lead bromide(FAPbBr_(3))nanocrystals(NCs)have been considered to be a good optoelectronic material due to their pure green emission,excellent stability and superior carrier transport characteristics.However,two-photon pumped amplified spontaneous emission(ASE)and the corresponding nonlinear optical properties of FAPbBr_(3) NCs are scarcely revealed.Herein,we synthesized colloidal FAPbBr_(3) NCs with different sizes by changing the molar ratio of FABr/PbBr_(2) in the precursor solution,using ligand assisted precipitation(LARP)technology at room temperature.Photoluminescence(PL)and time resolved photoluminescence(TRPL)spectroscopy were measured to characterize their ASE properties.And their nonlinear optical properties were studied through the Zscan technique and the two-photon excited fluorescence method.The stimulated emission properties including oneand two-photon pumped ASE have been realized from FAPbBr_(3) NCs.With large two-photon absorption coefficient(0.27 cm/GW)and high non-linear absorption cross-section(7.52×10^(5) GM),ASE with threshold as low as 9.8μJ/cm^(2) and 487μJ/cm^(2) have been obtained from colloidal FAPbBr_(3) NCs using one-and two-photon excitations.These results indicate that as a new possible green-emitting frequency-upconversion material with low thresholds,FAPbBr_(3) NCs hold great potential in the development of high-performance two-photon pump lasers. 展开更多
关键词 perovskites formamidinium lead bromide nanocrystals NONLINEAR optical gain amplified spontaneous emission
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Photosynthetic response dynamics in the invasive species Tithonia diversifolia and two co-occurring native shrub species under fluctuating light conditions
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作者 Ju Li Shu-Bin Zhang Yang-Ping Li 《Plant Diversity》 SCIE CAS CSCD 2024年第2期265-273,共9页
To determine the invasiveness of invasive plants,many studies have compared photosynthetic traits or strategies between invasive and native species.However,few studies have compared the photosynthetic dynamics between... To determine the invasiveness of invasive plants,many studies have compared photosynthetic traits or strategies between invasive and native species.However,few studies have compared the photosynthetic dynamics between invasive and native species during light fluctuations.We compared photosynthetic induction,relaxation dynamics and leaf traits between the invasive species,Tithonia diversifolia and two native species,Clerodendrum bungei and Blumea balsamifera,in full-sun and shady habitats.The photosynthetic dynamics and leaf traits differed among species.T.diversifolia showed a slower induction speed and stomatal opening response but had higher average intrinsic water-use efficiency than the two native species in full-sun habitats.Thus,the slow induction response may be attributed to the longer stomatal length in T.diversifolia.Habitat had a significant effect on photosynthetic dynamics in T.diversifolia and B.balsamifera but not in C.bungei.In shady habitat,T.diversifolia had a faster photosynthetic induction response than in full-sun habitat,leading to a higher average stomatal conductance during photosynthetic induction in T.diversifolia than in the two native species.In contrast,B.balsamifera had a larger stomatal length and slower photosynthetic induction and relaxation response in shady habitat than in full-sun habitat,resulting in higher carbon gain during photosynthetic relaxation.Nevertheless,in both habitats,T.diversifolia had an overall higher carbon gain during light fluctuations than the two native species.Our results indicated that T.diversifolia can adopt more effective response strategies under fluctuating light environments to maximize carbon gain,which may contribute to its successful invasion. 展开更多
关键词 Invasive plant Photosynthetic induction Photosynthetic relaxation Carbon gain Stomatal traits Tithonia diversifolia
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What Is the Impact of Major Diversion Attitude on Undergraduates' Learning Gains?--The Mediating Role of Course Perception
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作者 Qintao Sun Yueqi Shi 《教育技术与创新》 2023年第1期1-15,共15页
Major diversion is an important part of the large-category student enrollment and training model.The degree to which undergraduates recognize the logic of the major diversion system,their satisfaction with the diverte... Major diversion is an important part of the large-category student enrollment and training model.The degree to which undergraduates recognize the logic of the major diversion system,their satisfaction with the diverted major,and their major identity after diversion all influence their subsequent learning process and outcomes.The questionnaire survey of undergraduates in this study discovered that major diversion attitude has a significant positive effect on undergraduates'learning gains;the mediating effect test discovered that course perception plays a partially mediating role between major diversion attitude and learning gains.Therefore,under the large-category student enrollment and training model,it is necessary to improve the major diversion system in terms of formulation,major selection guidance,and major identity promotion.Furthermore,strengthening the logical connection and content coupling of different types of courses,dealing with the proportion,priority,and sequence of courses,optimizing the allocation of course resources,and reasonably planning and setting courses all play an important role in improving undergraduate learning gains. 展开更多
关键词 the large-category enrollment and training major diversion attitude course perception learning gains
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基于ATE的高速DAC射频参数SFDR测试技术优化
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作者 沈锺杰 张一圣 +1 位作者 孔锐 王建超 《现代电子技术》 北大核心 2024年第2期16-20,共5页
利用集成电路自动测试设备(ATE)测试高速DAC射频参数时,由于ATE测试板PCB走线较长、损耗较大以及机台提供的信号抖动比实装大等原因,导致ATE上高速DAC射频参数测试指标低于实装测试值。为此,文中介绍DAC电路的工作原理和测试方法;其次... 利用集成电路自动测试设备(ATE)测试高速DAC射频参数时,由于ATE测试板PCB走线较长、损耗较大以及机台提供的信号抖动比实装大等原因,导致ATE上高速DAC射频参数测试指标低于实装测试值。为此,文中介绍DAC电路的工作原理和测试方法;其次为解决上述问题,对测试码的生成以及PCB的布局等进行一系列改进,并将改进前后的测试值与典型值进行对比。结果表明,改进措施成效显著,大大优化了高速DAC射频参数的测试指标,使得SFDR等高频DAC动态类参数指标接近或达到实装测试值。 展开更多
关键词 集成电路 自动测试设备(atE) 高速数模转换器 射频参数 SFDR参数 测试码 PCB测试板
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