arXiv subjects

Q. M. Li

Publications and source records attributed to Q. M. Li.

8 recordsLinked to original sources

arXiv2025

Revisiting the energy distribution and formation rate of CHIME fast radio bursts

Based on the first CHIME/FRB catalogue, three volume-limited samples of fast radio bursts (FRBs) are built, with samples 1, 2, and 3 corresponding to a fluence cut of 5, 3, and 1, respectively. The Lynden-Bell's c$^-$ method was applied to study their energy function and event rate evolution with redshift ($z$). Using the non-parametric Kendall's $τ$ statistics, it is found that the FRB energy ($E$) strongly evolves with redshift as $E(z)\varpropto(1+z)^{1.24}$ for sample 1, $E(z)\varpropto(1+z)^{0.98}$ for sample 2, and $E(z)\varpropto(1+z)^{1.99}$ for sample 3. After removing the redshift dependence, the local energy distributions of the three samples can be well described by a broken power-law form with a broken energy of $\sim10^{40} \rm erg$. Meanwhile, the redshift distributions of samples 1 and 2 are identical but different from that of sample 3. Interestingly, we find that the event rates of samples 1 and 2 are independent of redshift, and sample 3 decreases as a single power-law form with an index of -2.41. The local event rates of the three samples of CHIME FRBs are found to be consistently close to $\sim 10^4\rm{\,Gpc^{-3}yr^{-1}}$, which is comparable with some previous estimates. In addition, we notice that the event rate of sample 3 FRBs with lower energies not only exceeds the star formation rate at the lower redshifts but also always declines with the increase in redshift. We suggest that the excess of FRB rates compared with the star formation rate at low redshift mainly results from the low-energy FRBs that could originate in the older stellar populations.

astro-ph.HE↗

arXiv2024

Determination of dynamic flow stress equation based on discrete experimental data: Part 1 Methodology and the dependence of dynamic flow stress on strain-rate

In this study, a framework to determine the dynamic flow stress equation of materials based on discrete data of varied (or instantaneous) strain-rate from split Hopkinson pressure bar (SHPB) experiments is proposed. The conventional constant strain-rate requirement in SHPB test is purposely relaxed to generate rich dynamic flow stress data which are widely and diversely distributed in plastic strain and strain-rate space. Two groups of independent SHPB tests, i.e. Group A (without shaper) and Group B (with shaper) were conducted on the C54400 phosphor-bronze copper alloy at room temperature, obtaining flow stress data (FSD) (two-dimensional (2D) matrix). Data qualification criteria were proposed to screen the FSD, with which qualified FSD were obtained. The qualified FSD of Group A were coarsely filled with missing data and were reconstructed by the Artificial Neural Network (ANN). As a result, finely-filled FSD of Group A were obtained, which were carefully evaluated by the qualified FSD of Group B. The evaluation proves the effectiveness of ANN in FSD prediction. Next, the finely-filled FSD from Group A were decomposed by Singular Value Decomposition (SVD) method. Discrete and analytical flow stress equation f(strain, strain-rate)_ana were obtained from the SVD results. Finally, flow stress equation (f(strain, strain-rate)_MJC) based on conventional method were established. Five uncertainties inherent in the conventional method in the determination of the flow stress equation were identified. The comparison between f(strain, strain-rate)_ana and f(strain, strain-rate)_MJC demonstrated the effectiveness and reliability of the flow stress equation obtained from the proposed method.

physics.app-ph↗

arXiv2023

New evidence of multiple channels for the origin of gamma-ray bursts with extended emission

Gamma-ray bursts (GRBs) are the most intense explosions in the universe. GRBs with extended emission (GRB EE) constitute a small subclass of GRBs. GRB EE are divided into EE-I GRBs and EE-II GRBs, according to the Amati empirical relationship rather than duration. We test here if these two types of GRB have different origins based on their luminosity function (and formation rate). Therefore, we use Lynden-Bell's c^- method to investigate the LF and FR of GRBs with EE without any assumption. We calculate the formation rate of two types of GRBs. For EE-I GRBs, the fitting function can be written as ρ(z) \propto {(1 + z)^{ - 0.34 \pm 0.04} for z < 2.39 and ρ(z) \propto {(1 + z)^{ - 2.34 \pm 0.24}} for z>2.39. The formation rate of EE-II can describe as ρ(z) \propto {(1 + z)^{ - 1.05 \pm 1.10}} for z<0.43 and ρ(z) \propto {(1 + z)^{ - 8.44 \pm 1.10}} for z>0.43. The local formation rate are ρ(0) = 0.03 Gpc^{-3}yr^{-1} for some EE-I GRBs and ρ(0) = 0.32 Gpc^{-3}yr^{-1} for EE-II GRBs. Based on these results, we provide a new evidence that the origins of EE-I GRBs are different from EE-II GRBs from the perspective of event rate. The EE-I GRB could be produced from the death of the massive star, but EE-II GRB bursts may come from other processes that are unrelated to the SFR. Our findings indicate that the GRB with EE could have multiple production channels.

astro-ph.HE↗

arXiv2023

Properties of Gamma-Ray Bursts Associated with Supernovae and Kilonovae

We systematically compare the temporal and spectral properties of 53 Supernova (SN)-associated and 15 Kilonova (KN)-associated Gamma-Ray Bursts (GRBs). We find that the spectral parameters of both types GRBs are identically and lognormally distributed, consistent with those normal GRBs. The bolometric luminosities of SN/GRBs and KN/GRBs have a triple form with the corresponding break luminosities of SN/GRBs are roughly two orders of magnitude larger than those of KN/GRBs. We build the power-law relations between the spectral lag and the luminosity of prompt $γ$-rays with indices of $-1.43\pm0.33$ for SN/GRBs and $-2.17\pm0.57$ for KN/GRBs in the laboratory frame, which are respectively coincident with the rest-frame values. We verify that both SN/GRBs and KN/GRBs comply with their own Amati relations that match those of long and short GRBs, respectively. Analyzing X-ray afterglows with good plateau segments, we build the power-law relations between the X-ray luminosity and the plateau time with an index of $-1.12\pm0.17$ for KN/GRBs and $-1.08\pm0.22$ for SN/GRBs, which can be well explained by the relativistic shock driven by an energy injection. The plots of luminosity-lag, Amati relation and luminosity-time show heavy overlap between the two types of GRBs, implying that they might share the same radiation mechanism despite originating from different progenitors or central engines.

astro-ph.HE↗

arXiv2023

The origin of low-redshift event rate excess as revealed by the low-luminosity GRBs

The relation between the event rate of long Gamma-Ray Bursts at low redshift and the star formation rate is still controversial, especially in the low-redshift end. Dong et al. confirmed that the Gamma-Ray Burst rate always exceeds the star formation rate at low-redshift of z < 1 in despite of the sample completeness. However, the reason of low-redshift excess is still unclear. Considering low-luminosity bursts with smaller redshift generally, we choose three Swift long burst samples and classify them into low- and high-luminosity bursts in order to check whether the low-redshift excess is existent and if the excess is biased by the sample size and completeness. To degenerate the redshift evolution from luminosity, we adopt the non-parametric method to study the event rate of the two types of long bursts in each sample. It is found that the high-luminosity burst rates are consistent with the star formation rate within the whole redshift range while the event rates of low-luminosity bursts exceed the star formation rate at low redshift of z < 1. Consequently, we conclude that the low-redshift excess is contributed by the low-luminosity bursts with possibly new origins unconnected with the star formation, which is also independent of the sample size and the sample completeness.

astro-ph.HE↗

arXiv2022

Evaluation of methods for the determination of tortuosity of Li-ion battery separators

The porosities and tortuosities are commonly utilized to characterize the microstructure of a Li-ion battery's separator and are adopted as key input parameters in advanced battery models. Herein, a general classification of the tortuosity for a porous medium is introduced based on its bi-fold significance, i.e., the geometrical and physical tortuosities. Then, three different methods for the determination of separator's electrical tortuosity are introduced and compared, which include the empirical Bruggeman equation, the experimental method using Electrochemical Impedance Spectrum (EIS) testing a the numerical method using realistic 3D microstructure of the separator obtained from nanoscale X-ray Computed Tomography (XCT). In addition, the connection between the geometrical tortuosity and the electrical tortuosity of a separator is established by introducing the electrical phenomenological factor (\b{eta}_e), which can facilitate the understanding of the relationship between the microstructure characteristics and transport properties of the separators. Furthermore, to quantitively compare the values of the tortuosities determined by different methods, the corresponding effective transport coefficients (δ) are compared, which was usually used as a correction for effective diffusivity and conductivity of electrolytes in porous media.

physics.app-ph↗

arXiv2020

Metric of Shock Severity

Shock response spectrum (SRS) is a widely accepted method for shock testing specification. However, SRS, as a supremum, is over-conservative and cannot fully describe the relative severity for various shock environments. This study introduces shock response matrix, from which shock severity infimum (SSI) can be extracted using singular value decomposition method. Based on SRS and SSI, dual spectra are introduced to determine the range of shock severity between its supremum and infimum. The evaluation of the relative severity of various shock signals is discussed and validated by finite element simulations.

eess.SP↗

arXiv2020

Design and implementation of the net zero displacement filter for the synthesis of a mechanical shock signal under specified shock response spectrum

Electronic and optical products are vulnerable under mechanical shock environment. Designed products need to be validated by shock testing and/or numerical simulation, using representative acceleration-time history signals. However, specifications derived from measurements are normally given in terms of shock response spectrum (SRS) without a corresponding time history signal, and therefore, there is a need to synthesis acceleration-time histories from a given SRS specification. This paper proposed a net zero displacement filter and a realistic time history synthesis method. By scaling a relevant field measurement, acceleration-time histories can be synthesized, which can meet the net zero displacement constrain and a given SRS specification within $\pm$3 dB margin.

eess.SP↗