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| 1 | Variable scale-convex-peak method for weak signal detection显示文摘Avariable scale-convex-peak method is constructed to identify the frequency of weak harmonic signal. The key of this method is to find a set of optimal identification coefficients to make the transition of dynamic behavior topologically persistent. By the stochastic Melnikov method, the lower bound of the chaotic threshold continuous function is obtained in the mean-square sense.The intermediate value theorem is applied to detect the optimal identification coefficients. For the designated identification system, there is a valuable co-frequency-convex-peak in bifurcation diagram, which indicates the state transition of chaosperiod-chaos. With the change of the weak signal amplitude and external noise intensity in a certain range, the convex peak phenomenon is still maintained, which leads to the identification of frequency. Furthermore, the proposition of the existence of reversible scaling transformation is introduced to detect the frequency of the harmonic signal in engineering. The feasibility of constructing the hardware and software platforms of the variable scale-convex-peak method is verified by the experimental results of circuit design and the results of early fault diagnosis of actual bearings, respectively. | TIAN RuiLan ZHAO ZhiJie XU Yong | 2021 | Science China(Technological Sciences)2021，64，2： | 2 |
| 2 | The codimension-two bifurcation for the recent proposed SD oscillator显示文摘 | Ruilan Tian Qingjie Cao Shaopu Yang | 2010 | Nonlinear Dynamics2010，，1： | 1 |
| 3 | Bifurcations and chaotic thresholds for the spring-pendulum oscillator with irrational and fractional nonlinear restoring forces显示文摘 | Ruilan Tian Qiliang Wu Yeping Xiong Xinwei Yang Wenjie Feng | 2014 | The European Physical Journal Plus2014，，5： | 1 |
| 4 | The codimension-two bifurcation for the recent proposed SD?oscillator显示文摘 | Ruilan Tian Qingjie Cao Shaopu Yang | 2010 | Nonlinear Dynamics (-)2010，，1： | 1 |
| 5 | Reed-wetland beds for municipal wastewater treatment显示文摘The performance of 11 reed-wetland beds for municipal wastewater treatment is described in this paper. The interrelation between pollutants removal (BOD5, SS, N and P) and hydraulic loading rate, organic loading rate, hydraulic retention time as well as the seasonal variation could be found in this study. The treatment efficiencies of reed beds are better than the secondary treatment standards with high and steady nitrogen and phosphorus removal. The total nitrogen and phosphorus of the final effluent are less than 10 mg/L and 0.5 mg/L, respectively. | Tang Yunping, Mi Ruilan and Zhao JinlingTianjin Environmental Protection Institute, Tianjin 300191, ChinaShen Weiran and Tian ShuhuiTianjin Environmental Monitoring Center, Tianjin 300191, China | 1992 | Journal of Environmental Sciences1992，4，1： | 0 |
| 6 | Periodic-phase-diagram similarity method for weak signal detection显示文摘The periodic-phase-diagram similarity method is proposed to identify the frequency of weak harmonic signals.The key technology is to find a set of optimal coefficients for Duffing system,which leads to the periodic motion under the influence of weak signal and strong noise.Introducing the phase diagram similarity,the influences of strong noise on the similarity of periodic phase diagram are discussed.The principle of highest similarity of periodic phase diagram with the same frequency is detected by discussing the persistence of similarity of periodic motion phase diagram under the strong noise and the periodic-phase-diagram similarity method is constructed.The weak signals of early fault and strong noise are input into Duffing system to obtain the identified system.The stochastic subharmonic Melnikov method is extended to obtain the conditions of the optimal coefficients for the identified system.Based on the results,the constructed frequency conversion harmonic weak signals are considered to form a datum periodic system.With the change of frequency in the datum periodic system,the phase diagram similarity of the two constructed systems can be calculated.Based on the periodic-phase-diagram similarity method,the frequency of weak harmonic signals can be identified by the principle of highest similarity of periodic phase diagram with the same frequency.The results of numerical simulation and the early fault diagnosis results of actual bearings verify the feasibility of the periodic-phase-diagram similarity method.The accuracy of the detection effect is 97%,and the minimum signal-to-noise ratio is−80.71 dB. | Ruilan Tian Yangkun Zhang Shaopu Yang Kai Yuan Qiang Xue Quanrong Ren | 2021 | International Journal of Mechanical System Dynamics2021，1，2： | 0 |
| 7 | Theoretical and experimental study of a bi-stable piezoelectric energy harvester under hybrid galloping and band-limited random excitations显示文摘In the practical environment,it is very common for the simultaneous occurrence of base excitation and crosswind.Scavenging the combined energy of vibration and wind with a single energy harvesting structure is fascinating.For this purpose,the effects of the wind speed and random excitation level are investigated with the stochastic averaging method(SAM)based on the energy envelope.The results of the analytical prediction are verified with the Monte-Carlo method(MCM).The numerical simulation shows that the introduction of wind can reduce the critical excitation level for triggering an inter-well jump and make a bi-stable energy harvester(BEH)realize the performance enhancement for a weak base excitation.However,as the strength of the wind increases to a particular level,the influence of the random base excitation on the dynamic responses is weakened,and the system exhibits a periodic galloping response.A comparison between a BEH and a linear energy harvester(LEH)indicates that the BEH demonstrates inferior performance for high-speed wind.Relevant experiments are conducted to investigate the validity of the theoretical prediction and numerical simulation.The experimental findings also show that strong random excitation is favorable for the BEH in the range of low wind speeds.However,as the speed of the incoming wind is up to a particular level,the disadvantage of the BEH becomes clear and evident. | Haitao LI Tianyu ZHENG Weiyang QIN Ruilan TIAN Hu DING J.C.JI Liqun CHEN | 2024 | Applied Mathematics and Mechanics(English Edition)2024，45，3： | 0 |
| 8 | Quantifying the parameter dependent basin of the unsafe regime of asymmetric Lévy-noise-induced critical transitions显示文摘In real systems,the unpredictable jump changes of the random environment can induce the critical transitions(CTs)between two non-adjacent states,which are more catastrophic.Taking an asymmetric Lévy-noise-induced tri-stable model with desirable,sub-desirable,and undesirable states as a prototype class of real systems,a prediction of the noise-induced CTs from the desirable state directly to the undesirable one is carried out.We first calculate the region that the current state of the given model is absorbed into the undesirable state based on the escape probability,which is named as the absorbed region.Then,a new concept of the parameter dependent basin of the unsafe regime(PDBUR)under the asymmetric Lévy noise is introduced.It is an efficient tool for approximately quantifying the ranges of the parameters,where the noise-induced CTs from the desirable state directly to the undesirable one may occur.More importantly,it may provide theoretical guidance for us to adopt some measures to avert a noise-induced catastrophic CT. | Jinzhong MA Yong XU Yongge LI Ruilan TIAN Shao juan MA J.KURTHS | 2021 | Applied Mathematics and Mechanics(English Edition)2021，42，1： | 0 |
| 9 | Dynamic crushing behavior and energy absorption of hybrid auxetic metamaterial inspired by Islamic motif art显示文摘Auxetic honeycomb structures are promising metamaterials with outstanding mechanical properties,and can be potentially used in energy absorption applications.In this study,a novel modified re-entrant hybrid auxetic metamaterial inspired by Islamic motif art is designed by integrating four-pointed double re-entrant motifs with symmetric semi-hexagonal unit cells to achieve a high energy absorption capacity(EAC).Theoretical analyses and numerical simulations are performed to examine the dynamic crushing behavior of the four-pointed double re-entrant combined structure(FDRCS).The developed finite element models(FEMs)are validated by the experiments under quasi-static compression.The deformation mode and stress-strain curves are further studied under low,medium,and high crushing velocities.The theoretically predicted plateau stress of the FDRCS under different crushing velocities is consistent with the numerical simulation results.The crushing stress and the EAC of the FDRCS are influenced by the geometric parameters and crushing velocities.The FDRCS exhibits a negative Poisson's ratio(NPR),owing to the four-point re-entrant structure(RES).Moreover,the specific energy absorption(SEA)of these structures is higher than that of nonauxetic hexagonal and auxetic re-entrant structures,owing to the generation of more plastic hinges that dissipate more energy during dynamic crushing. | Ruilan TIAN Huaitong GUAN Xuhao LU Xiaolong ZHANG Huanan HAO Wenjie FENG Guanglei ZHANG | 2023 | Applied Mathematics and Mechanics(English Edition)2023，44，3： | 0 |
| 10 | HIF-1αpromotes virus replication and cytokine storm in H1N1 virus-induced severe pneumonia through cellular metabolic reprogramming显示文摘The mortality of patients with severe pneumonia caused by H1N1 infection is closely related to viral replication and cytokine storm.However,the specific mechanisms triggering virus replication and cytokine storm are still not fully elucidated.Here,we identified hypoxia inducible factor-1α(HIF-1α)as one of the major host molecules that facilitates H1N1 virus replication followed by cytokine storm in alveolar epithelial cells.Specifically,HIF-1αprotein expression is upregulated after H1N1 infection.Deficiency of HIF-1αattenuates pulmonary injury,viral replication and cytokine storm in vivo.In addition,viral replication and cytokine storm were inhibited after HIF-1αknockdown in vitro.Mechanistically,the invasion of H1N1 virus into alveolar epithelial cells leads to a shift in glucose metabolism to glycolysis,with rapid production of ATP and lactate.Inhibition of glycolysis significantly suppresses viral replication and inflammatory responses.Further analysis revealed that H1N1-induced HIF-1αcan promote the expression of hexokinase 2(HK2),the key enzyme of glycolysis,and then not only provide energy for the rapid replication of H1N1 virus but also produce lactate,which reduces the accumulation of the MAVS/RIG-I complex and inhibits IFN-α/βproduction.In conclusion,this study demonstrated that the upregulation of HIF-1αby H1N1 infection augments viral replication and cytokine storm by cellular metabolic reprogramming toward glycolysis mainly through upregulation of HK2,providing a theoretical basis for finding potential targets for the treatment of severe pneumonia caused by H1N1 infection. | Xiaoxiao Meng Yong Zhu Wenyu Yang Jiaxiang Zhang Wei Jin Rui Tian Zhengfeng Yang Ruilan Wang | 2024 | Virologica Sinica2024，39，1： | 0 |
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