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直供电系统中电网调频方式研究 预览
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作者 唐长忠 《电工技术》 2019年第6期38-39,41共3页
本文分析了直供电系统网内频率变化特性,在优化网内机组调频的基础上,提出配置负荷调频措施来抑制电网的频率劣化,既能减轻机组调频装置频繁动作对调速系统的损坏,又有利于电网频率的快速恢复。
关键词 直供电系统 频率 机组调频方式 负荷调频
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Joint timing and frequency synchronization in coherent optical OFDM systems
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作者 Xinwei DU Pooi-Yuen KAM Changyuan YU 《中国光电子学前沿:英文版》 EI CSCD 2019年第1期4-14,共11页
In this paper,we review our joint timing and frequency synchronization algorithms in coherent optical orthogonal frequency division multiplexing(CO-OFDM)systems.We first present a timing estimation method by designing... In this paper,we review our joint timing and frequency synchronization algorithms in coherent optical orthogonal frequency division multiplexing(CO-OFDM)systems.We first present a timing estimation method by designing the pattern of the training symbol,whose timing metric has a sharp and clear peak,to ensure accurate timing offset(TO)estimation performance.Then we provide both data-aided(DA)and blind(BL)approaches to estimate the carrier frequency offset(CFO).For the DA algorithm,we utilize the same training symbol structure as the timing estimation does,while for the BL algorithm,we utilize the zero-subcarrier power(ZSP)to achieve full-range CFO estimation.Note that our joint timing and frequency synchronization approaches require only one OFDM symbol,which ensure not only the data transmission efficiency,but also the TO and CFO estimation performance.A modified BL ZSP algorithm is proposed to further improve the CFO estimation performance by taking the power average over a series of OFDM symbols.The effectiveness of the TO estimation algorithm,and both the DA and BL CFO estimation algorithms are verified and demonstrated in both simulations and experiments. 展开更多
关键词 timing OFFSET (TO) carrier FREQUENCY OFFSET (CFO) COHERENT OPTICAL orthogonal FREQUENCY division multiplexing (CO-OFDM) zero-subcarrier power (ZSP)
Quantitative SNR analysis of QFM signals in the LPFT domain with Gaussian windows
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作者 Yan-Na ZHANG Bing-Zhao LI +1 位作者 Navdeep GOEL Salvador GABARDA 《中国科学:信息科学(英文版)》 SCIE EI CSCD 2019年第2期127-141,共15页
The purpose of this paper is to present a quantitative SNR analysis of quadratic frequency modulated(QFM)signals.This analysis is located in the continuous-time local polynomial Fourier transform(LPFT)domain using a G... The purpose of this paper is to present a quantitative SNR analysis of quadratic frequency modulated(QFM)signals.This analysis is located in the continuous-time local polynomial Fourier transform(LPFT)domain using a Gaussian window function based on the definition of 3 dB signal-to-noise ratio(SNR).First,the maximum value of the local polynomial periodogram(LPP),and the 3 dB bandwidth in the LPFT domain for a QFM signal is derived,respectively.Then,based on these results,the 3 dB SNR of a QFM signal with Gaussian window function is given in the LPFT domain with one novel idea highlighted:the relationship among standard SNR,parameters of QFM signals and Gaussian window function is clear,and the potential application is demonstrated in the parameter estimation of a QFM signal using the LPFT.Moreover,the 3 dB SNR in the LPFT domain is compared with that in the linear canonical transform(LCT)domain.The validity of theoretical derivations is confirmed via simulation results.It is shown that,in terms of SNR,QFM signals in the LPFT domain can achieve a significantly better performance than those in the LCT domain. 展开更多
关键词 SNR ANALYSIS QUADRATIC FREQUENCY modulated signal local polynomial Fourier TRANSFORM linear CANONICAL TRANSFORM time FREQUENCY representations
Formulation of Determining the Gravity Potential Difference Using Ultra-High Precise Clocks via Optical Fiber Frequency Transfer Technique
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作者 Ziyu Shen Wen-Bin Shen +3 位作者 Zhao Peng Tao Liu Shougang Zhang Dingbo Chao 《地球科学学刊:英文版》 SCIE CAS CSCD 2019年第2期422-428,共7页
Based on gravity frequency shift effect predicted by general relativity theory, this study discusses an approach for determining the gravity potential(geopotential) difference between arbitrary two points P and Q by r... Based on gravity frequency shift effect predicted by general relativity theory, this study discusses an approach for determining the gravity potential(geopotential) difference between arbitrary two points P and Q by remote comparison of two precise optical clocks via optical fiber frequency transfer. After synchronization, by measuring the signal’s frequency shift based upon the comparison of bidirectional frequency signals from P and Q oscillators connected with two optical atomic clocks via remote optical fiber frequency transfer technique, the geopotential difference between the two points could be determined, and its accuracy depends on the stabilities of the optical clocks and the frequency transfer comparison technique. Due to the fact that the present stability of optical clocks achieves 1.6×10-18 and the present frequency transfer comparison via optical fiber provides stabilities as high as 10-19 level, this approach is prospective to determine geopotential difference with an equivalent accuracy of 1.5 cm. In addition, since points P and Q are quite arbitrary, this approach may provide an alternative way to determine the geopotential over a continent, and prospective potential to unify a regional height datum system. 展开更多
关键词 GRAVITY FREQUENCY shift OPTICAL fiber FREQUENCY TRANSFER OPTICAL clock GRAVITY potential
联轴部分对转轮自振频率计算结果的影响分析 预览
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作者 卜良峰 吉敏刚 《大电机技术》 2019年第1期51-56,共6页
本文以一个电厂结构为分析基础,选取了一个完整的转轮和不同轴身长度作为计算模型,计算出了转轮不同节径的自振频率。对计算结果和不同振型进行了分析,对转轮自振频率与激振频率的关系进行了分析,给出了设计时对转轮自振频率计算模型的... 本文以一个电厂结构为分析基础,选取了一个完整的转轮和不同轴身长度作为计算模型,计算出了转轮不同节径的自振频率。对计算结果和不同振型进行了分析,对转轮自振频率与激振频率的关系进行了分析,给出了设计时对转轮自振频率计算模型的选取及对计算结果的影响和取值方面的指导性意见,对结构优化调整转轮自振频率具有一定的指导意义。 展开更多
关键词 混流式水轮机 转轮 计算模型 频率 节径 结构优化 有限元分析 自振频率
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中药汤剂治疗颈动脉粥样硬化患者临床用药规律分析 预览
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作者 张文将 易健 刘柏炎 《中国医药导报》 CAS 2019年第13期128-131,共4页
目的探索中医药治疗颈动脉粥样硬化的用药规律。方法运用关键词查找的方法在万方、维普、知网数据库上检索2005年1月~2017年12月的文献,最终符合要求的文献共109篇,运用Excel表格建立数据库,并对药物使用的频次、频率、四气、五味、归... 目的探索中医药治疗颈动脉粥样硬化的用药规律。方法运用关键词查找的方法在万方、维普、知网数据库上检索2005年1月~2017年12月的文献,最终符合要求的文献共109篇,运用Excel表格建立数据库,并对药物使用的频次、频率、四气、五味、归经、药物类别、治则治法运用SPSS软件进行统计分析。结果文献共使用药物147味,使用频次为1007次。使用频次最高的药物是丹参、川芎、黄芪。药性以温、寒、平为主,累计频率为92.3%;五味以甘、苦、辛为主,累计频率为90.4%;归经以肝、脾、心为主,累计频率为86.4%;药物类别以活血化瘀药、补气药、补血药、温化寒痰药为主,累计频率为45.1%。结论中药汤剂治疗颈动脉粥样硬化以活血化瘀为主。 展开更多
关键词 中医药 颈动脉粥样硬化 用药规律 频次
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神经外科监护病房高频接触物体表面消毒频次的研究 预览
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作者 张晶 周晶 +3 位作者 田洋洋 宋岩 于鸿源 纪微 《中国感染控制杂志》 CAS CSCD 北大核心 2019年第4期331-334,共4页
目的通过对神经外科监护病房(ICU)高频接触物体表面消毒现状的调查,探讨最佳消毒频次。方法选取吉林大学第一医院神经外科ICU内的床栏、微量泵、监护仪按钮、洗手液按压开关、鼠标、病历的物体表面共6项为研究对象。分别于消毒后2、4、6... 目的通过对神经外科监护病房(ICU)高频接触物体表面消毒现状的调查,探讨最佳消毒频次。方法选取吉林大学第一医院神经外科ICU内的床栏、微量泵、监护仪按钮、洗手液按压开关、鼠标、病历的物体表面共6项为研究对象。分别于消毒后2、4、6、8h进行采样,培养48h后读取菌落数。比较不同消毒后时间点的菌落数。结果床栏和监护仪按钮消毒后不同时间点采样菌落数比较,差异无统计学意义(均P>0.05),平均菌落数均<5CFU/cm2。微量泵、洗手液按压开关、鼠标、病历消毒后不同时间点采样菌落数比较,差异具有统计学意义(均P<0.05);该四类物体表面消毒后8h的菌落数均高于消毒后6h(均P<0.05)。结论ICU内不同高频接触物体表面的污染情况存在一定差异,应根据高频接触物体表面的实际情况制定最佳的消毒频次。 展开更多
关键词 高频接触物体表面 神经外科 重症监护病房 消毒 频次
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Vector mode based optical direct detection orthogonal frequency division multiplexing transmission in short-reach optical link
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作者 Jianping LI Zhaohui LI 《中国光电子学前沿:英文版》 EI CSCD 2019年第1期41-51,共11页
As one solution to implement the largecapacity space division multiplexing(SDM)transmission systems,the mode division multiplexing(MDM)has gained much attention recently.The vector mode(VM),which is the eigenmode of t... As one solution to implement the largecapacity space division multiplexing(SDM)transmission systems,the mode division multiplexing(MDM)has gained much attention recently.The vector mode(VM),which is the eigenmode of the optical fiber,has also been adopted to realize the optical communications including the transmission over free-space optical(FSO)and optical fiber links.Considering the concerns on the short-reach optical interconnects,the low cost and high integration technologies should be developed.Direct detection(DD)with higher-order modulation formats in combination of MDM technologies could offer an available trade-off in system performance and complexity.We review demonstrations of FSO and fiber high-speed data transmission based on the VM MDM(VMDM)technologies.The special VMs,cylindrical vector beams(CVB),have been generated by the q-plate(QP)and characterized accordingly.And then they were used to implement the VMDM transmission with direct-detection orthogonal frequency division multiplexing(DD-OFDM).These demonstrations show the potential of VMDM-DD-OFDM technology in the large-capacity short-reach transmission links. 展开更多
关键词 space DIVISION MULTIPLEXING (SDM) MODE DIVISION MULTIPLEXING (MDM) few-mode fiber (FMF) VECTOR MODE (VM) cylindrical VECTOR beam (CVB) orthogonal frequency DIVISION MULTIPLEXING (OFDM) direct detection (DD) OPTICAL interconnect
低气压环境下噪声特性对人体烦躁感的影响 预览
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作者 管宏宇 胡松涛 +3 位作者 慕缘鹏 刘国丹 尹晓燕 王岳振 《科学技术与工程》 北大核心 2019年第14期90-94,共5页
为了探究低气压环境下不同噪声特性对人员舒适度的影响,对常压及低气压环境下噪声对人员烦躁感的影响开展了实验研究。结果显示:烦躁感随着噪声声压级的升高而增加,低气压环境下烦躁感较常压环境低;女性对噪声的变化更敏感,烦躁感更强烈... 为了探究低气压环境下不同噪声特性对人员舒适度的影响,对常压及低气压环境下噪声对人员烦躁感的影响开展了实验研究。结果显示:烦躁感随着噪声声压级的升高而增加,低气压环境下烦躁感较常压环境低;女性对噪声的变化更敏感,烦躁感更强烈;烦躁感随着噪声持续时间有累积效应,超过15 min之后,人员会产生适应性;阶跃变化会影响人体舒适度,噪声阶跃升高会增加烦躁感,噪声阶跃降低,烦躁感会降低,但较低分贝稳态噪声环境下,阶跃变化烦躁感更强烈。该研究可为低气压环境下声环境研究提供参考。 展开更多
关键词 低气压 频率 声压级 阶跃变化 烦躁感
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高速编码器在流量计量中的应用 预览
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作者 杨智 裴锐 《仪器仪表用户》 2019年第9期45-47,共3页
详细分析的X2控制器用于高速IO测量的4种测量方式:累加计数、正交计数、频率计数和脉宽计数.通过对X2控制器编程实现了欧姆龙编码器累积脉冲、旋转方向、旋转圈数的计量,进而验证了高速编码器用于工业流量计量的可行性.工业编码器可靠性... 详细分析的X2控制器用于高速IO测量的4种测量方式:累加计数、正交计数、频率计数和脉宽计数.通过对X2控制器编程实现了欧姆龙编码器累积脉冲、旋转方向、旋转圈数的计量,进而验证了高速编码器用于工业流量计量的可行性.工业编码器可靠性强,应用灵活,可以有效地提升容积式流量计的现场计量效率. 展开更多
关键词 编码器 X2控制器 累积 频率 正交 脉冲
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基于振动分析的转速测试系统设计 预览
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作者 张宇 谢群 +2 位作者 丛培田 张秀珩 陈茂双 《光电技术应用》 2019年第3期48-52,共5页
针对封闭式旋转机械转速测量的需求,提出了一种通过振动分析的转速测试方法。由于机械转子质量分布不均匀,转子在转动过程中必然会产生简谐振动。并且振动的频率与转子转动的频率相等,从而就将转子转速的测量转化到转子振动的频率测量... 针对封闭式旋转机械转速测量的需求,提出了一种通过振动分析的转速测试方法。由于机械转子质量分布不均匀,转子在转动过程中必然会产生简谐振动。并且振动的频率与转子转动的频率相等,从而就将转子转速的测量转化到转子振动的频率测量上来。利用振动测试传感器将机械振动信号拾取出来,并通过信号调理电路,将振动信号转变成具有一定强度的电压信号,用AD数据采集模块将这个电压信号采集并传送给计算机进行处理。应用Visual Basic6.0软件平台根据最小条件系统识别理论编写转速测试系统,对采集来的振动数据进行处理,从而计算出封闭式旋转机械的转速。附有转速测试系统的软件设计流程图,进行了现场测试实验,分析测试系统的可行性和误差。 展开更多
关键词 振动分析 封闭式旋转机械 VISUAL BASIC6.0 最小条件 频率 转速
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Teacher’s Code-switching to L1 in Chinese College EFL Class 预览
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作者 Yang Ning 《教育理论综述(英文)》 2019年第2期34-41,共8页
The paper tries to explore teachers’ code-switching to Chinese in EFL classroom. Quantitative and qualitative research methods are adopted in the study. The case study centers on showing the attitude of teachers and ... The paper tries to explore teachers’ code-switching to Chinese in EFL classroom. Quantitative and qualitative research methods are adopted in the study. The case study centers on showing the attitude of teachers and that of students towards the CS to L1. It indicated that both teachers and students had positive attitude toward CS to Chinese in EFL classroom. The results in the classroom recording showed that students’ English proficiency level influenced the frequency of teachers’ CS;teachers alternate to Chinese mainly to facilitate students’ understanding or to emphasize some key points. 展开更多
关键词 Teacher's CODE-SWITCHING ATTITUDE Frequency PROFICIENCY level
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承压含水层中孔压变化规律的振动台实验研究 预览
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作者 张耀文 谷洪彪 +2 位作者 那金 宋洋 张艳 《科学技术与工程》 北大核心 2019年第17期18-24,共7页
为研究不同地震动作用下承压含水层中孔压变化规律及其主要影响因素,开展了基于地震模拟振动台的承压含水层孔隙水压力变化实验研究。结果表明:①地震动作用下孔压变化形态可分为振荡、振荡上升以及阶升三种类型,孔压变化形态及幅度均... 为研究不同地震动作用下承压含水层中孔压变化规律及其主要影响因素,开展了基于地震模拟振动台的承压含水层孔隙水压力变化实验研究。结果表明:①地震动作用下孔压变化形态可分为振荡、振荡上升以及阶升三种类型,孔压变化形态及幅度均与加速度峰值密切相关,而与频率相关度较低;②孔压增量随加速度峰值增大而增大,其增长规律可表示为以加速度峰值为自变量的二次函数;③孔压消散过程基本呈线性规律,且消散速率与加速度峰值大小有关,加速度峰值越大,振后孔压消散速率越快。实验可为后续探究地震动作用下孔压变化信息在含水层中的传递机理提供一定参考。 展开更多
关键词 孔压 加速度峰值 频率 振动台实验
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Special Section on Energy-Efficient TechnologiesCurrent Issue | Archive | Adv Search | Energy Harvesting—Technical Analysis of Evolution, Control Strategies, and Future Aspects 预览
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作者 MD. Shahrukh Adnan Khan Md. Tanbhir Hoq +3 位作者 A. H. M. Zadidul Karim Md. Khairul Alam Masum HowladerRajkumar Rajprasad Kumar 《电子科技学刊:英文版》 CAS CSCD 2019年第2期116-125,共10页
This paper provides a technical analysis of energy harvesting (EH) in the field of power and energy sector, including different aspects of harvesting energy, individual case history, control strategies of harvesting i... This paper provides a technical analysis of energy harvesting (EH) in the field of power and energy sector, including different aspects of harvesting energy, individual case history, control strategies of harvesting in the field of power and energy sector together with the current trend and future aspects of it. EH is comparatively a new concept which is growing very fast since the 20th century and catching new generation research approaches. This paper not only describes the past and current scenarios of harvesting energy with radio frequency (RF) and renewables but also gives author’s own anticipation of the upcoming future trends of it by comparing the case histories. 展开更多
关键词 Energy HARVESTING (EH) PIEZOELECTRIC radio frequency (RF) solar triboelectric wind
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石家庄汉族血小板捐献者HPA1-17基因多态性分析
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作者 李茵 苏蔓 +7 位作者 何路军 赵倩 胡光磊 赵佳 谢晶 钱明明 张泓楠 王振雷 《中国输血杂志》 CAS 2019年第5期427-429,共3页
目的 建立石家庄地区已知HPA基因型别单采血小板捐献者基因资料数据库,分析石家庄地区3591名汉族血小板捐献者HPA基因多态性分布特点。方法 HPA基因分型采用聚合酶链反应—序列特异引物(PCR-SSP)方法,计算等位基因频率、基因型频率及HPA... 目的 建立石家庄地区已知HPA基因型别单采血小板捐献者基因资料数据库,分析石家庄地区3591名汉族血小板捐献者HPA基因多态性分布特点。方法 HPA基因分型采用聚合酶链反应—序列特异引物(PCR-SSP)方法,计算等位基因频率、基因型频率及HPA-1~17组合型频率。结果 3 591名无血缘关系的血小板捐献者HPA基因HPA-7~14、HPA-16、HPA-17系统均为aa纯合子,未检出b等位基因。HPA-1~6、15中杂合度最高的为HPA-3系统,不配合率为37.44%;其次为HPA-15系统,不配合率为37.40%;HPA-4系统的杂合度最低,不配合率仅为0.38%;与国内部分地区人群数据比较分析,发现石家庄地区汉族血小板捐献者HPA-5系统分布与国内其他地区人群存在显著差异。结论 建立了石家庄地区血小板捐献者HPA-1~17基因分型数据库,可为患者提供HPA相合的血小板,对减少临床血小板输注无效的发生具有重要意义。 展开更多
关键词 血小板 HPA 血小板输注无效 频率
Using irrigation intervals to optimize water-use efficiency and maize yield in Xinjiang,northwest China 预览
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作者 Guoqiang Zhang Dongping Shen +10 位作者 Bo Ming Ruizhi Xie Xiuliang Jin Chaowei Liu Peng Hou Jun Xue Jianglu Chen Wanxu Zhang Wanmao Liu Keru Wang Shaokun Li 《作物学报:英文版》 CAS CSCD 2019年第3期322-334,共13页
Worldwide, scarce water resources and substantial food demands require efficient water use and high yield.This study investigated whether irrigation frequency can be used to adjust soil moisture to increase grain yiel... Worldwide, scarce water resources and substantial food demands require efficient water use and high yield.This study investigated whether irrigation frequency can be used to adjust soil moisture to increase grain yield and water use efficiency(WUE) of high-yield maize under conditions of mulching and drip irrigation.A field experiment was conducted using three irrigation intervals in 2016: 6, 9, and 12 days(labeled D6, D9, and D12) and five irrigation intervals in 2017: 3, 6, 9, 12, and 15 days(D3, D6, D9, D12, and D15).In Xinjiang, an optimal irrigation quota is 540 mm for high-yield maize.The D3, D6, D9, D12, and D15 irrigation intervals gave grain yields of 19.7, 19.1–21.0, 18.8–20.0, 18.2–19.2, and 17.2 Mg ha^-1 and a WUE of 2.48, 2.53–2.80, 2.47–2.63, 2.34–2.45, and 2.08 kg m-3, respectively.Treatment D6 led to the highest soil water storage, but evapotranspiration and soil-water evaporation were lower than other treatments.These results show that irrigation interval D6 can help maintain a favorable soil-moisture environment in the upper-60-cm soil layer, reduce soilwater evaporation and evapotranspiration, and produce the highest yield and WUE.In this arid region and in other regions with similar soil and climate conditions, a similar irrigation interval would thus be beneficial for adjusting soil moisture to increase maize yield and WUE under conditions of mulching and drip irrigation. 展开更多
关键词 IRRIGATION frequency Soil MOISTURE MAIZE High YIELD (>15 Mg ha^?1) Water use efficiency
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Genome-wide dissection of segregation distortion using multiple inter-subspecific crosses in rice
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作者 Guangwei Li Jiye Jin +5 位作者 Yan Zhou Xufeng Bai Donghai Mao Cong Tan Gongwei Wang Yidan Ouyang 《中国科学:生命科学英文版》 SCIE CAS CSCD 2019年第4期507-516,共10页
Mendelian inheritance can ensure equal segregation of alleles from parents to offspring,which provides fundamental basis for genetics and molecular biology.Segregation distortion(SD)leads to preferential transmission ... Mendelian inheritance can ensure equal segregation of alleles from parents to offspring,which provides fundamental basis for genetics and molecular biology.Segregation distortion(SD)leads to preferential transmission of certain alleles from generation to generation.Such violation of Mendelian genetic principle is often accompanied by reproductive isolation and eventually speciation.Although SD is observed in a wide range of species from plants to animals,genome-wide dissection of such biased transmission of gametes is rare.Using nine inter-subspecific rice crosses,a genome-wide screen for SD loci is performed,which reveals 61 single-locus quantitative trait loci and 194 digenic interactions showing distorted transmission ratio,among which 24 new SD loci are identified.Biased transmission of alleles is observed in all nine crosses,suggesting that SD exists extensively in rice populations.72.13% distorted regions are repeatedly detected in multiple populations,and the most prevalent SD hotspot that observed in eight populations is mapped to chromosome 3.Xian alleles are transmitted at higher frequencies than geng alleles in inter-subspecific crosses,which change the genetic composition of the rice populations.Epistatic interaction contributes significantly to the deviation of Mendelian segregation at the whole-genome level in rice,which is distinct from that in animals.These results provide an extensive archive for investigating the genetic basis of SD in rice,which have significant implications in understanding the reproductive isolation and formation of inter-subspecific barriers during the evolution. 展开更多
关键词 Oryza sativa xian/indica geng/japonica segregation distortion REPRODUCTIVE isolation ALLELE frequency
Frequency control of future power systems: reviewing and evaluating challenges and new control methods 预览
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作者 Zeyad Assi OBAID Liana M.CIPCIGAN +1 位作者 Lahieb ABRAHIM Mazin T.MUHSSIN 《现代电力系统与清洁能源学报(英文)》 CSCD 2019年第1期9-25,共17页
Integration of more renewable energy resources introduces a challenge in frequency control of future power systems.This paper reviews and evaluates the possible challenges and the new control methods of frequency in f... Integration of more renewable energy resources introduces a challenge in frequency control of future power systems.This paper reviews and evaluates the possible challenges and the new control methods of frequency in future power systems.Different types of loads and distributed energy resources(DERs) are reviewed.A model representation of a population of the water heater devices for the demand side frequency response is considered.A model representation of a population of battery energy storage system(BESS)-based DERs such as smart electric vehicles(EVs) charging, large-scale BESSs, and residential and non-residential BESSs, are highlighted.The simplified Great Britain power system and the 14-machine South-East Australian power system were used to demonstrate the effectiveness of the new methods in controlling power system frequency following a disturbance.These new methods are effective in recovering the fallen frequency response and present a great potential in controlling the frequency in future power systems. 展开更多
关键词 Battery ENERGY storage system(BESS) Distributed ENERGY resource(DER) Electric vehicle HOME-BASED BESS Large-scale BESS AGGREGATION Demand side response Frequency control Markov chain
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不同面密度吸声板对声屏障结构影响研究 预览
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作者 黄涛 常婷婷 于梦阁 《中国铁路》 2019年第4期85-91,共7页
针对吸声板面密度为40 kg/m~2和60 kg/m~2的2种直立插板式声屏障,基于有限元法计算声屏障结构的模态,并在台风荷载为8 000 Pa条件下,研究声屏障的稳态结构响应。研究结果表明:(1)这2种声屏障的1阶振动频率和2阶振动频率各不相同,3阶到6... 针对吸声板面密度为40 kg/m~2和60 kg/m~2的2种直立插板式声屏障,基于有限元法计算声屏障结构的模态,并在台风荷载为8 000 Pa条件下,研究声屏障的稳态结构响应。研究结果表明:(1)这2种声屏障的1阶振动频率和2阶振动频率各不相同,3阶到6阶模态相差不大;(2)当吸声板面密度为60 kg/m~2时,声屏障结构具有较好的稳定性。并提出建议:(1)在保证吸声降噪效果的前提下,建议吸声板面密度选择60 kg/m~2;(2)在台风载荷作用下,声屏障结构会发生破坏,建议结构设计时在H形支座底部合理布置一定数量的加强筋板或将H形支座材料改为Q275钢。 展开更多
关键词 声屏障 面密度 结构 模态 频率 应力
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基于振动减阻原理的吸力式基础纠偏试验研究 预览
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作者 谢立全 林田田 《高技术通讯》 CAS 北大核心 2019年第1期53-59,共7页
吸力式基础作为一种新兴的海洋锚泊基础,具有运输便捷、施工快、节省材料等优点。但吸力式基础在复杂多变的海洋环境以及海床地质条件贯入过程中易发生倾斜,严重影响自身的承载功能。本文针对海底吸力式基础的沉贯倾斜问题,展开一系列试... 吸力式基础作为一种新兴的海洋锚泊基础,具有运输便捷、施工快、节省材料等优点。但吸力式基础在复杂多变的海洋环境以及海床地质条件贯入过程中易发生倾斜,严重影响自身的承载功能。本文针对海底吸力式基础的沉贯倾斜问题,展开一系列试验,采用振动减阻原理达到纠偏效果。试验分别研究了在不同振动频率、不同初始倾斜角、不同静压荷载作用下的基础纠偏过程。结果表明,倾斜的吸力式基础可通过侧壁振动方式实现有效纠偏,其纠偏效果与振动频率、初始倾斜角以及静压荷载息息相关:相同激振力作用下,激振频率越大(25~75Hz),所需纠偏时间越短;桶基的初始倾斜角越大,则完全纠偏所需时间越长,且呈非线性增加;贯入荷载(或贯入深度)越大,纠偏难度越大,纠偏越早(贯入深度越小)越容易。 展开更多
关键词 吸力式基础 倾斜 振动 纠偏 频率
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