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Prospect for Cosmological Parameter Estimation Using Future Hubble Parameter Measurements

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Communications in Theoretical Physics 2018年第10期70卷 445-450页

作者： jia-jia geng Rui-Yun Guo An-Zhong Wang Jing-Fei Zhang Xin Zhang Institute for Advanced Physics & Mathematics Zhejiang University of Technology Hangzhou 310032 China Department of Physics College of Sciences Northeastern University Shenyang 110004 China GCAP-CASPER Department of Physics Baylor University Waco TX 76798-7316 USA Center for High Energy Physics Peking University Beijing 100080 China Center for Gravitation and Cosmology Yangzhou University Yangzhou 225009 China

We constrain cosmological parameters using only Hubble parameter data and quantify the impact of future Hubble parameter measurements on parameter estimation for the most typical dark energy models. We first constrain cosmological parameters using 52 current Hubble parameter data including the Hubble constant measurement from the Hubble Space Telescope. Then we simulate the baryon acoustic oscillation signals from WFIRST(Wide-Field Infrared Survey Telescope) covering the redshift range of z ∈ [0.5, 2] and the redshift drift data from E-ELT(European Extremely Large Telescope) in the redshift range of z ∈ [2, 5]. It is shown that solely using the current Hubble parameter data could give fairly good constraints on cosmological parameters. Compared to the current Hubble parameter data, with the WFIRST observation the H(z) constraints on dark energy would be improved slightly, while with the E-ELT observation the H(z) constraints on dark energy is enormously improved.

关键词： dark energy cosmological parameter constraints Hubble parameter measurements

采用端口阻抗测试的车载充电机传导电磁干扰建模方法研究

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西安交通大学学报 2025年第1期59卷 172-182页

作者：李季风耿宇宇贾晋廖兴林路青洋重庆理工大学电气与电子工程学院重庆400054 重庆理工大学汽车零部件先进制造技术教育部重点实验室重庆400054

针对电动汽车车载充电机的设计过程中普遍存在的电磁干扰频率范围广、干扰源复杂的问题,提出了一种基于端口阻抗测试的等效电路建模和系统级协同仿真方法。首先,通过对车载充电机系统各部件进行阻抗测试和三维电磁仿真,建立了无源器件... 详细信息

针对电动汽车车载充电机的设计过程中普遍存在的电磁干扰频率范围广、干扰源复杂的问题,提出了一种基于端口阻抗测试的等效电路建模和系统级协同仿真方法。首先,通过对车载充电机系统各部件进行阻抗测试和三维电磁仿真,建立了无源器件、端口滤波器和高压屏蔽线缆模型,提取了系统印制电路板关键回路的高频寄生参数。其次,建立了有源器件的仿真电路模拟器等效模型,并通过双脉冲实验验证模型的精度;针对功率因数校正电路控制环节的仿真与建模难以同步实现的问题,采用协同建模的方法构建整个系统的等效电路模型。最后,将各部件模型组合在一起,建立了完整的车载充电机系统传导电磁干扰预测模型,并依据相关测试标准进行了系统传导电磁干扰仿真和实验。结果表明:在150 kHz~30 MHz频率范围内,预测结果与实际结果的误差小于9 dB,具有良好的一致性,表明该模型能够精确预测车载充电机系统高压交流端的传导干扰水平,可以有效指导充电机系统的电磁兼容正向设计。

关键词：车载充电机电磁干扰端口阻抗测试协同仿真

Structural engineered living materials

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Nano Research 2024年第2期17卷 715-733页

作者： Yang geng Zian jia Ling Li 635 Prices Fork Road Department of Mechanical EngineeringVirginia Polytechnic Institute and State UniversityBlacksburg VA24061USA

Biological structural materials not only exhibit remarkable mechanical properties but also often embody dynamic characteristics such as environmental responsiveness,autonomy,and self-healing,which are difficult to achieve in conventional engineering *** merging materials science,synthetic biology,and other disciplines,engineered living materials(ELMs)provide a promising solution to combine living organisms with abiotic components,thus facilitating the construction of functional“living”*** natural materials,ELMs possess vitality and hold immense application potential in areas such as medicine,electronics,and construction,captivating increasing research attention *** an emerging branch of ELMs,structural ELMs aim to mimic living biological structural materials by achieving desired mechanical performance while maintaining important“living”*** we summarize the recent progress and provide our perspectives for this emerging research *** first summarize the superiority of structural ELMs by reviewing biological structural materials and biomimetic material design ***,we provide a systematic discussion on the definition and classifications of structural ELMs,their mechanical performance,and physiological ***,we summarize some critical challenges faced by structural ELMs and highlight directions of future *** hope this review article can provide a timely summary of the state of the art and relevant perspectives for future development of structural ELMs.

关键词： structural materials engineered living materials(ELMs) structural ELMs composites mechanical properties

PREPARATION OF SINGLE-HOLE HOLLOW POLYMER NANOSPHERES BY RASPBERRY-LIKE TEMPLATE METHOD

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Chinese Journal of Polymer Science 2013年第2期31卷 294-301页

作者： Yong Zhang jia-jia Chen geng-hui Zhang Bai-zhu Chen 阎虎生 Key laboratory of Functional Polymer Materials (Ministry of Education) Institute of Polymer Chemistry Nankai University

Single-hole hollow polymer nanospheres were fabricated by raspberry-like template method using ＂graft-from＂ strategy through atom transfer radical polymerization （ATRP）. Nanometer-sized silica spheres were covalently attached onto the surfaces of micrometer-sized silica spheres. Crosslinked polymer shells on the nano-sized spheres outside the attached area were formed by ＂graft-from＂ strategy through ATRP. After removal of the silica cores, single-hole hollow crosslinked polymer nanospheres were obtained. In this strategy, most of ATRP monomers may be used and thus many functional groups can be easily incorporated into the single-hole hollow crosslinked polymer nanospheres.

关键词： Single-hole Hollow polymeric nanoparticles ATRP.

Network boundary recognition via relative azimuth angle

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The Journal of China Universities of Posts and Telecommunications 2010年第4期17卷 31-41页

作者： jia Rui-wu SHI geng-chen National Lab of Mechatronic Engineering and Control Beijing Institute of Technology Beijing 100081 China

To recognize the boundary of wireless networks to meet some specific needs, relative azimuth angles of nodes distributed in the 1-hop neighborhood of each node in one network were used to recognize the boundary of the network. A novel recognition algorithm based on local generalized convex hull was proposed for one node to decide if it self is a boundary node. The flexibility, efficiency and consistency of the algorithm are shown in its performance by extensive simulations.

关键词： wireless sensor network boundary point generalized convex hull relative azimuth angle θ-hull

A novel dynamic equivalence method for grid-connected wind farm

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第4期9卷 558-563页

作者： jia-geng QIAO Zong-xiang LU Yong MIN State Key Laboratory of Power Systems Department of Electrical Engineering Tsinghua University Beijing 100084 China

Dynamic equivalence of the wind farm is a fundamental problem in the simulation of a power system connected with wind farms because it is unpractical to model every generator in a wind farm in detail. In this paper, an Equivalence Method based on the Output Characteristics (EMOC) is proposed, with which the wind farm composed of Squirrel-Cage Induction Generators (SCIGs) can be equivalent to one generator. By considering the diversity of wind generators and special operating characteristics of a wind farm, the equivalent generator based on EMOC responds accurately in various faults. No matter whether the wind farm is integrated in grid or just programmed, EMOC can be used to acquire an accurate equivalent generator. Simulation of the dynamic equivalence of an SCIG wind farm validated the method.

关键词： Grid-connected wind farm Dynamic equivalence Squirrel-Cage Induction Generator (SCIG) Genetic algorithm

High-frequency vibration analysis of thin plate based on wavelet-based FEM using B-spline wavelet on interval

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Science China(Technological Sciences) 2017年第5期60卷 792-806页

作者： geng jia ZHANG XingWu CHEN XueFeng XUE XiaoFeng State Key Laboratory for Manufacturing Systems Engineering School of Mechanical Engineering Xi 'an Jiaotong University Xi'an 710049 China

The wavelet finite element methods （WFEMs） own higher calculation accuracy and efficiency for structure analysis. Unfortunately, the existing WFEMs are still limited in low-frequency domain when capturing dynamic characteristics of thin plate. This paper proposes the wavelet multi-elements method based on C1 type B-spline Kirchhoff plate （CIBKP） element to break up this limitation. The validity, numerical stability and convergence respectively are investigated systematically in numerical study. The corresponding results show that the calculation accuracy and numerical stability are very excellent when predicting the high-order natural frequency. The maximum relative errors can be rapidly reduced to 0.4% within the first 1000 modes of thin plate under simply supported. Besides, the method is suitable for predicting the dynamic characteristics of thin plate under various boundary conditions.

关键词： high-order natural frequency thin plate plate bending vibrations wavelet multi-elements method

Load identification in one dimensional structure based on hybrid finite element method

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Science China(Technological Sciences) 2017年第4期60卷 538-551页

作者： XUE XiaoFeng CHEN XueFeng ZHANG XingWu geng jia State Key Laboratory for Manufacturing System Engineering School of Mechanical Engineering Xi'an Jiaotong University Xi'an 710049 China

The new hybrid elements are proposed by combing modified Hermitian wavelet elements with ANASYS elements. Then hybrid elements are substituted into finite element formulations to solve the load identification. Transfer matrix can be constructed by using the inverse Newmark algorithm and hybrid finite element method. Loads can obtain through the responses and the transfer matrix. Load identification law was studied under different excitation cases in rod and Timoshenko *** method is adopted to solve ill-posed inverse problem of load identification. Compared with ANSYS results,hybrid elements and HCSWI elements can accurately identify the applied load. Numerical results show that the algorithm of hybrid elements is effective. The accuracy of hybrid elements and HCSWI elements can be verified by comparing the load identification result of ANASYS elements with the experiment data. Hermitian wavelet finite element methods have high accuracy advantage but it is difficult to apply the engineering practice. In practical engineering, complex structure can be analyzed by using the hybrid finite element methods which can be obtained the high accuracy in the crucial component.

关键词： hybrid finite element method Hermitian wavelet elements load identification regularization method

Marginal Land-based Biomass Energy Production in China

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Journal of Integrative Plant Biology 2010年第1期52卷 112-121页

作者： Ya Tang jia-Sui Xie Shu geng Department of Environment College of Architecture and Environment Sichuan University Chengdu 610065 China School of Environment and Energy Peking University Shenzhen Graduate School Shenzhen 518055 China University of California Davis California 95616 USA

Fast economic development in China has resulted in a significant increase in energy demand. Coal accounts for 70% of China＇s primary energy consumption and its combustion has caused many environmental and health problems. Energy security and environmental protection requirements are the main drivers for renewable energy development in China. Small farmland and food security make bioenergy derived from corn or sugarcane unacceptable to China： the focus should be on generating bioenergy from lignocellulosic feedstock sources. As China cannot afford biomass energy production from its croplands, marginal lands may play an important role in biomass energy production. Although on a small scale, marginal land has already been used for various purposes. It is estimated that some 45 million hm2 of marginal land could be brought into high potential biomass energy production. For the success of such an initiative, it will likely be necessary to develop multipurpose plants. A case study, carried out on marginal land in Ningnan County, Sichuan Province with per capita cropland of 0.07 ha, indicated that some 380 000 tons of dry biomass could be produced each year from annual pruning of mulberry trees. This study supports the feasibility of producing large quantities of biomass from marginal land sources.

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