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Detecting Very-High-Frequency Relic Gravitational Waves by a Waveguide

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Chinese Journal of Astronomy and Astrophysics 2008年第3期8卷 314-328页

作者： ming-lei tong Yang Zhang Centre for Astrophysics University of Science and Technology of China Hefei 230026 China

The polarization vector （PV） of an electromagnetic wave （EW） will experience a rotation in a region of spacetime perturbed by gravitational waves （GWs）. Based on this consideration, Cruise＇s group has built an annular waveguide to detect GWs. We give detailed calculations of the rotations of polarization vector of an EW caused by incident GWs from various directions and in various polarization states, and then analyze the accumulative effects on the polarization vector when the EW passes n cycles along the annular waveguide. We reexamine the feasibility and limitation of this method to detect GWs of high frequency around 100 MHz, in particular the relic gravitational waves （RGWs）. By comparing the spectrum of RGWs in the accelerating universe with the detector sensitivity of the current waveguide, it is found that the amplitude of the RGWs is too low to be detected by the waveguide detectors currently operating. Possible ways of improvements on detection are suggested.

关键词： early universe -- instrumentation detectors -- gravitational waves --polarization

Wiener Filtration Algorithm of an Ensemble Pulsar Timescale Based on a Power-law Model of Pulsar Power Spectrum

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Research in Astronomy and Astrophysics 2022年第10期22卷 129-140页

作者： Ting-Gao Yang ming-lei tong Yu-Ping Gao National Time Service Center Chinese Academy of SciencesXi'an 710600China Key Laboratory of Time and Frequency Primary Standards Chinese Academy of SciencesXi'an 71000China University of Chinese Academy of Sciences Beijing 100049China

An ensemble pulsar timescale derived from the traditional Wiener filtration still contains some high level *** improve this situation we developed a Wiener filtration algorithm of the ensemble pulsar timescale based on a power-law model of power spectrum for *** algorithm has three strengths:(1)mitigating spectral leakage between frequency bins for Fourier techniques;(2)using a power-law model for power spectrum;(3)signal realization in original residuals of data set by the power-law *** to improved algorithm we constructed an ensemble pulsar timescale EPT-TAI using timing data with respect to International Atomic Time(TAI)about 16 yr time span of ten pulsars from International Pulsar Timing Array second data release(version A).The results show that EPT-TAI detected correctly the differences TT(BIPM2015)-TAI between terrestrial time TT(BIPM2015)and *** frequency stabilityσzanalysis shows that EPT-TAI does not indicate red noise for 16 yr time interval,and fractional frequency stability for 8 yr and longer time intervals is slightly better than that of TT(BIPM2015)-*** for short time intervals of TT(BIPM2015)-TAI is better than that of EPT-TAI,but TT(BIPM2015)-TAI shows red noise for longer time *** the same algorithm we also derived an ensemble pulsar timescale EPT-TT(BIPM2015)with respect to TT(BIPM2015).The fractional frequency stability curve of EPT-TT(BIPM2015)shows similar characteristics as that of EPT-TAI but with slightly lower values.

关键词： (stars:)pulsars general-time-methods data analysis

The influence of the observational strategies of pulsar timing on the properties of pulsar clocks

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Research in Astronomy and Astrophysics 2020年第12期20卷 323-329页

作者： Zhe-Hao Zhang ming-lei tong Cheng-Shi Zhao Xing-Zhi Zhu Feng Gao National Time Service Center Chinese Academy of SciencesXi’an 710000China Key Laboratory of Time and Frequency Primary Standard Chinese Academy of SciencesXi’an 710600China University of Chinese Academy of Sciences Beijing 100049China Department of Applied Physics Xi’an University of Science and TechnologyXi’an 710054China

Pulsars are very stable spinning stars, which have the potential to application in the work of time-keeping and autonomous navigation in deep space. For time application, an individual pulsar can be regarded as a clock. The accuracy and stability of a pulsar clock are mainly determined by various timing noises and the measurement errors;however, they would be affected by the concrete observational *** four millisecond pulsars from the first data released by International Pulsar Timing Array(IPTA) as an example, we investigated the influences of different observational strategies on the properties of pulsar clocks by removing some data in various ways. We find that the long-term stabilities of pulsar clocks are nearly not affected by increasing the observational cadence with a fixed time span. It is also found that the capabilities of prediction by pulsar clocks are also hardly affected by different observational strategies,which is reflected by both the stable weighted root-mean-square(wrms) and the stability of the resulting pre-fit timing residuals, unless the data span is too short or the data period is too far from the start of prediction.

关键词： methods:data analysis time pulsars:general

The application of co-integration theory in ensemble pulsar timescale algorithm

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Research in Astronomy and Astrophysics 2019年第7期19卷 115-122页

作者： Feng Gao ming-lei tong Yu-Ping Gao Ting-Gao Yang Cheng-Shi Zhao National Time Service Center Chinese Academy of SciencesXi'an 710600China Key Laboratory of Time and Frequency Primary Standards Chinese Academy of SciencesXi'an 710600China University of Chinese Academy of Sciences Beijing 100049China Department of Applied Physics Xi'an University of Science and TechnologyXi'an 710054China

Employing multiple pulsars and using an appropriate algorithm to establish ensemble pulsar timescale can reduce the influences of various noises on the long-term stability of pulsar timescale,compared to a single ***,due to the low timing precision and significant red noises of some pulsars,their participation in the construction of ensemble pulsar timescale is often *** by the principle of solving non-stationary sequence modeling using co-integration theory,we put forward an algorithm based on co-integration theory to establish an ensemble pulsar *** is found that this algorithm can effectively suppress some noise sources if a co-integration relationship between different pulsar data *** from the classical weighted average algorithm,the co-integration method provides the chance for a pulsar with significant red noises to be included in the establishment of an ensemble pulsar *** on data from the North American Nanohertz Observatory for Gravitational Waves(NANOGrav),we found that the co-integration algorithm can successfully reduce several timing noises and improve the long-term stability of the ensemble pulsar timescale.

关键词： pulsars general-time-methods analytical

Pulsar timing residuals due to individual non-evolving gravitational wave sources

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Research in Astronomy and Astrophysics 2014年第4期14卷 390-400页

作者： ming-lei tong Cheng-Shi Zhao Bao-Rong Yan Ting-Gao Yang Yu-Ping Gao National Time Service Center Chinese Academy of Sciences Key Laboratory of Time and Frequency Primary Standards Chinese Academy of Sciences Key Laboratory of Precision Navigation and Timing Technology Chinese Academy of Sciences

The pulsar timing residuals induced by gravitational waves from non- evolving single binary sources are affected by many parameters related to the relative positions of the pulsar and the gravitational wave sources. We will analyze the various effects due to different parameters. The standard deviations of the timing residuals will be calculated with a variable parameter fixing a set of other parameters. The or- bits of the binary sources will be generally assumed to be elliptical. The influences of different eccentricities on the pulsar timing residuals will also be studied in detail. We find that the effects of the related parameters are quite different, and some of them display certain regularities.

关键词： gravitational waves: general -- pulsars: general -- binaries: general

Imprints of relic gravitational waves on pulsar timing

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Research in Astronomy and Astrophysics 2016年第3期16卷 111-120页

作者： ming-lei tong Yong-Heng Ding Cheng-Shi Zhao Feng Gao Bao-Rong Yan Ting-Gao Yang Yu-Ping Gao National Time Service Center Chinese Academy of SciencesXi'an 710600China Key Laboratory of Time and Frequency Primary Standards Chinese Academy of SciencesXi'an 710600China Key Laboratory for Research in Galaxies and Cosmology Chinese Academy of SciencesHefei 230026China University of Chinese Academy of Sciences Beijing 100049China Key Laboratory of Precision Navigation and Timing Technology Chinese Academy of SciencesXi'an 710600China

Relic gravitational waves （RGWs）, a background originating during inflation, would leave imprints on pulsar timing residuals. This makes RGWs an important source for detection of RGWs using the method of pulsar timing. In this paper, we discuss the effects of RGWs on single pulsar timing, and quantitatively analyze the timing residuals caused by RGWs with different model parameters. In principle, if the RGWs are strong enough today, they can be detected by timing a single millisecond pulsar with high precision after the intrinsic red noises in pulsar timing residuals are understood, even though simultaneously observing multiple millisecond pulsars is a more powerful technique for extracting gravitational wave signals. We correct the normalization of RGWs using observations of the cosmic microwave background （CMB）, which leads to the amplitudes of RGWs being reduced by two orders of magnitude or so compared to our previous works. We obtained new constraints on RGWs using recent observations from the Parkes Pulsar Timing Array, employing the tensor-to-scalar ratio r = 0.2 due to the tensor-type polarization observations of CMB by BICEP2 as a reference value, even though its reliability has been brought into question. Moreover, the constraints on RGWs from CMB and Big Bang nucleosynthesis will also be discussed for comparison.

关键词： gravitational waves: general -- pulsars: general -- inflation

Pulsar timing observations with Haoping Radio Telescope

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Research in Astronomy and Astrophysics 2020年第7期20卷 187-192页

作者： Jin-Tao Luo Yu-Ping Gao Ting-Gao Yang Cheng-Shi Zhao ming-lei tong Yong-Nan Rao Yi-Feng Li Bian Li Xing-Zhi Zhu Hai-Hua Qiao Xiao-Chun Lu National Time Service Center Chinese Academy of SciencesXi’an 710600China Key Lab of Precision Navigation&Timing Technology Chinese Academy of SciencesXi’an 710600China University of Chinese Academy of Sciences Beijing 100049China

We report pulsar timing observations carried out in L-band with NTSC’s 40-meter Haoping Radio Telescope(HRT),which was constructed in *** observations were carried out using the pulsar machine we *** observations toward millisecond pulsar J0437–4715 obtain a timing residual(r.m.s.)of 397 ns in the time span of 284 *** observations successfully detected Crab pulsar’s glitch that happened on 2019 July 23.

关键词： radio telescopes instrumentation:miscellaneous methods:data analysis pulsars:general

Boosting hydrocarbon conversion via Cu-doping induced oxygen vacancies on CeO2 in CO2 electroreduction

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Journal of Energy Chemistry 2025年第1期100卷 66-76页

作者： lei Xue tong Shi Chenhui Han Heng Zhang Fenrong Liu Haorun Li Yan Wang Xiaojun Gu Shanghong Zeng Inner Mongolia Key Laboratory of Chemistry and Physics of Rare Earth Materials School of Chemistry and Chemical Engineering Inner Mongolia University State Key Laboratory of Coal Conversion Institute of Coal Chemistry Chinese Academy of Sciences Institute of Catalysis Department of Chemistry Zhejiang University National Key Laboratory of Baiyunobo Rare Earth Resource Research and Comprehensive Utilization Baotou Research Institute of Rare Earths

Conversion of CO2back to hydrocarbons is the most direct way of closing the“carbon cycle”,and its significance is further enlarged if this process is driven by renewable energies such as ***,precisely controlling the product selectivity towards hydrocarbons against the competitive hydrogen evolution remains challenging,especially for Cu-based ***,we report a novel defect engineering strategy,by which Cu-doping-induced oxygen vacancies on CeO2nanorods were effectively created,with adjustable vacancy/Cu *** resulting optimum catalyst shows up to 79% catalytic current density to hydrocarbons （excluding CO）,with 49% faradaic efficiency to *** and density functional theory unveil that the ratio between oxygen vacancy and Cu affects significantly the formation of*CHO and activation of H2O,which leads to the following deep hydrogenation to *** findings may spur new insights for designing and developing more controllable chemical process relevant to CO2utilization.

关键词： Oxygen vacancy Hydrocarbon production Reaction mechanism

Multilevel analysis of the central-peripheral-target organ pathway:contributing to recovery after peripheral nerve injury

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Neural Regeneration Research 2025年第10期20卷 2807-2822页

作者： Xizi Song Ruixin Li Xiaolei Chu Qi Li Ruihua Li Qingwen Li Kai-Yu tong Xiaosong Gu Dong ming Academy of Medical Engineering and Translational Medicine Tianjin UniversityTianjinChina Haihe Laboratory of Brain-Machine Interface and Human-Machine Fusion TianjinChina Department of Rehabilitation Tianjin University Tianjin HospitalTianjinChina Department of Hand Microsurgery Tianjin University Tianjin HospitalTianjinChina School of Exercise and Health Tianjin University of SportTianjinChina Department of Biomedical Engineering the Chinese University of Hong KongHong Kong Special Administrative RegionChina

Peripheral nerve injury is a common neurological condition that often leads to severe functional limitations and *** on the pathogenesis of peripheral nerve injury has focused on pathological changes at individual injury sites,neglecting multilevel pathological analysis of the overall nervous system and target *** has led to restrictions on current therapeutic *** this paper,we first summarize the potential mechanisms of peripheral nerve injury from a holistic perspective,covering the central nervous system,peripheral nervous system,and target *** peripheral nerve injury,the cortical plasticity of the brain is altered due to damage to and regeneration of peripheral nerves;changes such as neuronal apoptosis and axonal demyelination occur in the spinal *** nerve will undergo axonal regeneration,activation of Schwann cells,inflammatory response,and vascular system regeneration at the injury *** damage to target organs can occur,including skeletal muscle atrophy and sensory receptor *** then provide a brief review of the research advances in therapeutic approaches to peripheral nerve *** main current treatments are conducted passively and include physical factor rehabilitation,pharmacological treatments,cell-based therapies,and physical ***,most treatments only partially address the problem and cannot complete the systematic recovery of the entire central nervous system-peripheral nervous system-target organ ***,we should further explore multilevel treatment options that produce effective,long-lasting results,perhaps requiring a combination of passive(traditional)and active(novel)treatment methods to stimulate rehabilitation at the central-peripheral-target organ levels to achieve better functional recovery.

关键词： central nervous system central peripheral target organ multilevel pathological analysis nerve regeneration peripheral nerve injury peripheral nervous system target organs therapeutic approach