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多径环境下脉冲超宽带系统的传输性能分析

林迪,沙学军,吴宣利,张乃通

《中国工程科学》 2009年 第11卷 第2期   页码 75-81

摘要：

为分析多径环境下脉冲超宽带跳时多址系统的传输性能，通过研究IEEE802.4.53a工作组给出的多 径信道参考模型，提出了一个同时存在符号间干扰、符号内多径干扰和多用户干扰的跳时超宽带系统相干解 调的性能分析模型，分别得到了符号内多径干扰、符号间干扰和多用户干扰的方差，且推导得到了系统的误 比特率计算公式，并用计算机仿真验证了公式的有效性。通过计算相邻多径的平均间隔，论证了符号内脉冲 自身多径的干扰是不可忽略的。在不同的信道环境下，以一定误码率要求作为衡量标准，比较了单用户系统 中仅考虑符号间干扰和同时考虑符号内多径干扰及符号间干扰的用户最高传输速率，并分析了多用户系统 中接入不同用户数时对应的平均传输速率的上限。

关键词： 超宽带     符号内多径干扰     符号间干扰     多用户干扰     传输性能分析模型    

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Choosing configurations of transmission line tower grounding by back flashover probability value

Dmitry KUKLIN

《能源前沿（英文）》 2016年 第10卷 第2期   页码 213-226 doi: 10.1007/s11708-016-0398-6

摘要： There is a considerable number of works devoted to electrical characteristics of grounding. These characteristics are important in general. However, in application to grounding of transmission line towers they are not enough to determine what grounding construction is preferable in some particular case, because these characteristics are calculated or measured apart from the grounded object, and only limited number of current (or voltage) source waveforms is used. This paper indicates reasons in favor of the fact that to choose the optimum design of grounding, the calculation model should include the tower as it is. The probability of back flashover, which provides both qualitative and quantitative estimate of the grounding structure efficiency, can be taken as the criterion for the grounding design. The insulation flashover probability is calculated on the basis of engineering method, which evaluates breakdown strength of insulation for nonstandard waveshapes, and probability data on lightning currents. Different approaches are examined for identifying the back flashover probability, as not only amplitudes but also other parameters can be taken into account. Finite-difference time-domain method is used for calculations of transients. It is found that lightning current waveform can greatly influence calculated back flashover probability value.

关键词： grounding     transmission line tower     back flashover probability     FDTD method    

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Recent transmission of Mycobacterium tuberculosis in China: the implication of molecular epidemiology

null

《医学前沿（英文）》 2018年 第12卷 第1期   页码 76-83 doi: 10.1007/s11684-017-0609-5

摘要：

Tuberculosis (TB) has remained an ongoing concern in China. The national scale-up of the Directly Observed Treatment, Short Course (DOTS) program has accelerated the fight against TB in China. Nevertheless, many challenges still remain, including the spread of drug-resistant strains, high disease burden in rural areas, and enormous rural-to-urban migrations. Whether incident active TB represents recent transmission or endogenous reactivation has helped to prioritize the strategies for TB control. Evidence from molecular epidemiology studies has delineated the recent transmission of ( ) strains in many settings. However, the transmission patterns of TB in most areas of China are still not clear. Studies carried out to date could not capture the real burden of recent transmission of the disease in China because of the retrospective study design, incomplete sampling, and use of low-resolution genotyping methods. We reviewed the implementations of molecular epidemiology of TB in China, the estimated disease burden due to recent transmission of strains, the primary transmission of drug-resistant TB, and the evaluation of a feasible genotyping method of strains in circulation.

关键词： tuberculosis     recent transmission     molecular epidemiology     China    

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Antibiotic resistome mostly relates to bacterial taxonomy along a suburban transmission chain

《环境科学与工程前沿（英文）》 2022年 第16卷 第3期 doi: 10.1007/s11783-021-1466-7

摘要：

• The α-diversities of resistome were lower in manure and compost than in soils.

关键词： Antibiotic resistance genes     Resistome     Bacterial taxonomy     Transmission chain    

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Planet position errors in planetary transmission: Effect on load sharing and transmission error

Miguel IGLESIAS, Alfonso FERNáNDEZ, Ana DE-JUAN, Ramón SANCIBRIáN, Pablo GARCíA

《机械工程前沿（英文）》 2013年 第8卷 第1期   页码 80-87 doi: 10.1007/s11465-013-0362-7

摘要：

In this paper an advanced model of spur gear transmissions developed by the authors is used to study the influence of carrier planet pin hole position errors on the behaviour of the transmission. The model, initially conceived for external gear modeling, has been extended with internal meshing features, and thus increasing its capabilities to include planetary transmission modeling. The new features are presented, along with the summary of the model general approach. The parameters and characteristics of the planetary transmission used in the paper are introduced. The influence of carrier planet pin hole position errors on the planet load sharing is studied, and several static cases are given as examples in order to show the ability of the model. Tangential and radial planet pin hole position errors are considered independently, and the effect of the load level is also taken into account. It is also given attention to the effect on the transmission error of the transmission. Two different configurations for the planetary transmission are used, attending to the fixed or floating condition of the sun, and the differences in terms of load sharing ratio are shown.

关键词： gear     planetary     epicyclic     transmission     load sharing     transmission error    

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Eliminating mother-to-child transmission of HBV: progress and challenges in China

Wenzhan Jing, Jue Liu, Min Liu

《医学前沿（英文）》 2020年 第14卷 第1期   页码 21-29 doi: 10.1007/s11684-020-0744-2

摘要： China has the world’s largest burden of hepatitis B virus (HBV) infection, but the country has made considerable progress in preventing its mother-to-child transmission (MTCT) in the past three decades. This feat is made possible due to the high coverage of birth-dose hepatitis B vaccine (HepB,>95%), hepatitis B surface antigen (HBsAg) screening for pregnant women (>99%), and hepatitis B immunoglobulin plus HepB for newborns whose mothers are HBsAg positive (>99%). Studies on the optimal antiviral treatment regimen for pregnant women with high HBV-DNA load have also been conducted. However, China still faces challenges in eliminating MTCT of HBV. The overall HBsAg prevalence among pregnant women is considered an intermediate endemic. The prevalence of HBsAg among pregnant women from remote, rural, or ethnic minority areas is higher than that of the national level because of limited health resources and public health education for HBV. The coverage for maternal and child healthcare and immunization services should be improved, especially in western regions. Integration of current services to prevent MTCT of HBV with other relevant health services can increase the acceptability, efficiency, and coverage of these services, particularly in remote areas and ethnic minority areas. By doing so, progress toward key milestones and targets to eliminate hepatitis B as the main public health threat by 2030 can be achieved.

关键词： hepatitis B virus     mother-to-child transmission     progress     challenge    

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An approach for evaluating the impact of an intermittent renewable energy source on transmission expansion

Rongrit CHATTHAWORN,Surachai CHAITUSANEY

《信息与电子工程前沿（英文）》 2015年 第16卷 第10期   页码 871-882 doi: 10.1631/FITEE.1500049

摘要： We propose a new robust optimization approach to evaluate the impact of an intermittent renewable energy source on transmission expansion planning (TEP). The objective function of TEP is composed of the investment cost of the transmission line and the operating cost of conventional generators. A method to select suitable scenarios representing the intermittent renewable energy generation and loads is proposed to obtain robust expansion planning for all possible scenarios. A meta-heuristic algorithm called adaptive tabu search (ATS) is employed in the proposed TEP. ATS iterates between the main problem, which minimizes the investment and operating costs, and the subproblem, which minimizes the cost of power generation from conventional generators and curtailments of renewable energy generation and loads. The subproblem is solved by nonlinear programming (NLP) based on an interior point method. Moreover, the impact of an intermittent renewable energy source on TEP was evaluated by comparing expansion planning with and without consideration of a renewable energy source. The IEEE Reliability Test System 79 (RTS 79) was used for testing the proposed method and evaluating the impact of an intermittent renewable energy source on TEP. The results show that the proposed robust optimization approach provides a more robust solution than other methods and that the impact of an intermittent renewable energy source on TEP should be considered.

关键词： Adaptive tabu search     Renewable energy generation     Robust optimization     Transmission expansion planning    

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Design and characteristic research of a novel electromechanical-hydraulic hybrid actuator with two transmission

《机械工程前沿（英文）》 2023年 第18卷 第2期 doi: 10.1007/s11465-022-0735-x

摘要： Servo-hydraulic actuators (SHAs) are widely used in mechanical equipment to drive heavy-duty mechanisms. However, their energy efficiency is low, and their motion characteristics are inevitably affected by uncertain nonlinearities. Electromechanical actuators (EMAs) possess superior energy efficiency and motion characteristics. However, they cannot easily drive heavy-duty mechanisms because of weak bearing capacity. This study proposes and designs a novel electromechanical-hydraulic hybrid actuator (EMHA) that integrates the advantages of EMA and SHA. EMHA mainly features two transmission mechanisms. The piston of the hydraulic transmission mechanism and the ball screw pair of the electromechanical transmission mechanism are mechanically fixed together through screw bolts, realizing the integration of two types of transmission mechanisms. The control scheme of the electromechanical transmission mechanism is used for motion control, and the hydraulic transmission mechanism is used for power assistance. Then, the mathematical model, structure, and parameter design of the new EMHA are studied. Finally, the EMHA prototype and test platform are manufactured. The test results prove that the EMHA has good working characteristics and high energy efficiency. Compared with the valve-controlled hydraulic cylinder system, EMHA exhibits a velocity tracking error and energy consumption reduced by 49.7% and 54%, respectively, under the same working conditions.

关键词： electromechanical-hydraulic hybrid actuator (EMHA)     integration     transmission mechanisms     power assistance     energy efficiency     working characteristics    

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Analysis of the kinematic characteristics of a high-speed parallel robot with Schönflies motion: Mobility, kinematics, and singularity

Fugui XIE,Xin-Jun LIU

《机械工程前沿（英文）》 2016年 第11卷 第2期   页码 135-143 doi: 10.1007/s11465-016-0389-7

摘要：

This study introduces a high-speed parallel robot with Schönflies motion. This robot exhibits a promising prospect in realizing high-speed pick-and-place manipulation for packaging production lines. The robot has four identical limbs and a single platform. Its compact structure and single-platform concept provides this robot with good dynamic response potential. A line graph method based on Grassmann line geometry is used to investigate the mobility characteristics of the proposed robot. A generalized Blanding rule is also introduced into this procedure to realize mutual conversion between the line graphs for motions and constraints. Subsequently, the inverse kinematics is derived, and the singularity issue of the robot is investigated using both qualitative and quantitative approaches. Input and output transmission singularity indices are defined based on the reciprocal product in screw theory and the virtual coefficient by considering motion/force transmission performance. Thereafter, the singular loci of the proposed robot with specific geometric parameters are derived. The mobility analysis, inverse kinematics modeling, and singularity analysis conducted in this study are helpful in developing the robot.

关键词： parallel robot     mobility     inverse kinematics     singularity     transmission performance    

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Aerosol transmission, an indispensable route of COVID-19 spread: case study of a department-store cluster

《环境科学与工程前沿（英文）》 2021年 第15卷 第3期 doi: 10.1007/s11783-021-1386-6

摘要：

• Aerosol transmission is an indispensable route of COVID-19 spread.

关键词： SARS-CoV-2     COVID-19     Environmental factor     Aerosol transmission     Epidemiologic characteristic    

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Interspecies transmission and evolution of the emerging coronaviruses: perspectives from bat physiology

Baicheng HUANG, Kegong TIAN

《农业科学与工程前沿（英文）》 2020年 第7卷 第2期   页码 218-226 doi: 10.15302/J-FASE-2020324

摘要：

Emergent coronaviruses (CoVs) such as SARS-CoV and MERS-CoV have posed great threats to public health worldwide over the past two decades. Currently, the emergence of SARS-CoV-2 as a pandemic causes greater public health concern. CoV diversity is due to the large size and replication mechanisms of the genomes together with having bats as their optimum natural hosts. The ecological behavior and unique immune characteristics of bats are optimal for the homologous recombination of CoVs. The relationship of spatial structural characteristics of the spike protein, a protein that is critical for recognition by host receptors, in different CoVs may provide evidence in explaining the coevolution of CoVs and their hosts. This information may help to enhance our understanding of CoV evolution and thus provide part of the basis of preparations for any future outbreaks.

关键词： bat     coronavirus     evolution     host receptor     spike protein     transmission    

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Reliability analysis of urban gas transmission and distribution system based on FMEA and correlation

Su LI,Weiguo ZHOU

《能源前沿（英文）》 2014年 第8卷 第4期   页码 443-448 doi: 10.1007/s11708-014-0336-4

摘要： In order to improve the safety management of urban gas transmission and distribution system, failure mode and effects analysis (FMEA) was used to construct the reliability analysis system of the pipeline network. To solve the problem of subjectivity and uncertainty of the multi-expert decision making, the correlation operator was introduced into the calculation of the risk priority number (RPN). Using FMEA along with weight analysis and expert investigation approach, the FMEA evaluation table was given, including five failure modes, risk priority numbers, failure causes and effects, as well as corrective actions. The results show that correlation operator can directly process the linguistic terms and quantify the priority of the risks.

关键词： gas transmission and distribution system     risk evaluation     reliability analysis     failure mode and effects analysis (FMEA)     correlation operator    

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Gray-box modeling and QFT control for precision servo transmission systems

Xiulan BAO, Xuedong CHEN, Xin LUO, Haocheng ZUO

《机械工程前沿（英文）》 2011年 第6卷 第4期   页码 442-448 doi: 10.1007/s11465-011-0242-y

摘要：

Precision servo transmission systems have widely been applied in industrial equipment to achieve high accuracy and high speed motion. However, due to the presence of friction and uncertainty, the characteristics of precision servo transmission systems are variant depends on the working conditions, leading to oscillation and instability in the system performances. In this paper, a grey-box model of the system is established, the model structure derived from the theoretical modeling and the model parameters are obtained by experiments using set membership identification method. This paper proposes two-degrees of freedom (2-DOF) robust position controller for a precision servo transmission system, based on the quantitative feedback theory (QFT), to achieve high accuracy and consistent tracking performance even in presence of considerable system uncertainties and friction disturbances. The results of simulate and experiment validate the effectiveness of the proposed controller.

关键词： precision servo transmission system     modeling     set membership identification     quantitative feedback theory (QFT)     robustness    

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Motion/force transmission indices of parallel manipulators

Xinjun LIU, Chao WU, Fugui XIE

《机械工程前沿（英文）》 2011年 第6卷 第1期   页码 89-91 doi: 10.1007/s11465-011-0215-1

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磁力金属带传动中传动比的影响因素分析

罗善明,缪协兴

《中国工程科学》 2002年 第4卷 第3期   页码 73-77

摘要：

对新型磁力金属带传动中传动比的影响因素，如有效牵引力、初张力、磁感应强度、中心距、小带轮直径及围包角等进行了分析和数值模拟，揭示了传动比随这些影响因素而变化的规律。结果表明，磁力金属带传动的传动比随磁感应强度、初张力及中心距的增大而增大，随围包角及小带轮直径的增大而减小。文中指出，由于磁力的作用，小带轮直径及其围包角均可相应减小，因此，其传动比较普通带传动可增加3～4倍。

关键词： 带传动     磁力     金属带     传动比    

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标题 作者 时间 类型 操作

多径环境下脉冲超宽带系统的传输性能分析

林迪,沙学军,吴宣利,张乃通

期刊论文

Choosing configurations of transmission line tower grounding by back flashover probability value

Dmitry KUKLIN

期刊论文

Recent transmission of Mycobacterium tuberculosis in China: the implication of molecular epidemiology

null

期刊论文

Antibiotic resistome mostly relates to bacterial taxonomy along a suburban transmission chain

期刊论文

Planet position errors in planetary transmission: Effect on load sharing and transmission error

Miguel IGLESIAS, Alfonso FERNáNDEZ, Ana DE-JUAN, Ramón SANCIBRIáN, Pablo GARCíA

期刊论文

Eliminating mother-to-child transmission of HBV: progress and challenges in China

Wenzhan Jing, Jue Liu, Min Liu

期刊论文

An approach for evaluating the impact of an intermittent renewable energy source on transmission expansion

Rongrit CHATTHAWORN,Surachai CHAITUSANEY

期刊论文

Design and characteristic research of a novel electromechanical-hydraulic hybrid actuator with two transmission

期刊论文

Analysis of the kinematic characteristics of a high-speed parallel robot with Schönflies motion: Mobility, kinematics, and singularity

Fugui XIE,Xin-Jun LIU

期刊论文

Aerosol transmission, an indispensable route of COVID-19 spread: case study of a department-store cluster

期刊论文

Interspecies transmission and evolution of the emerging coronaviruses: perspectives from bat physiology

Baicheng HUANG, Kegong TIAN

期刊论文

Reliability analysis of urban gas transmission and distribution system based on FMEA and correlation

Su LI,Weiguo ZHOU

期刊论文

Gray-box modeling and QFT control for precision servo transmission systems

Xiulan BAO, Xuedong CHEN, Xin LUO, Haocheng ZUO

期刊论文

Motion/force transmission indices of parallel manipulators

Xinjun LIU, Chao WU, Fugui XIE

期刊论文

磁力金属带传动中传动比的影响因素分析

罗善明,缪协兴

期刊论文