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| 1 | A new kind of optimal second-order symplectic scheme for seismic wave simulations显示文摘Here we introduce generalized momentum and coordinate to transform seismic wave displacement equations into Hamiltonian system.We define the Lie operators associated with kinetic and potential energy,and construct a new kind of second order symplectic scheme,which is extremely suitable for high efficient and long-term seismic wave simulations.Three sets of optimal coefficients are obtained based on the principle of minimum truncation error.We investigate the stability conditions for elastic wave simulation in homogeneous media.These newly developed symplectic schemes are compared with common symplectic schemes to verify the high precision and efficiency in theory and numerical experiments.One of the schemes presented here is compared with the classical Newmark algorithm and third order symplectic scheme to test the long-term computational ability.The scheme gets the same synthetic surface seismic records and single channel record as third order symplectic scheme in the seismic modeling in the heterogeneous model. | LIU ShaoLin LI XiaoFan WANG WenShuai LIU YouShan ZHANG MeiGen ZHANG Huan | 2014 | Science China Earth Sciences2014，57，4： | 8 |
| 2 | An efficient source wavefield reconstruction scheme using single boundary layer values for the spectral element method显示文摘In the adjoint-state method, the forward-propagated source wavefield and the backward-propagated receiver wavefield must be available simultaneously either for seismic imaging in migration or for gradient calculation in inversion. A feasible way to avoid the excessive storage demand is to reconstruct the source wavefield backward in time by storing the entire history of the wavefield in perfectly matched layers. In this paper, we make full use of the elementwise global property of the Laplace operator of the spectral element method (SEM) and propose an efficient source wavefield reconstruction method at the cost of storing the wavefield history only at single boundary layer nodes. Numerical experiments indicate that the accuracy of the proposed method is identical to that of the conventional method and is independent of the order of the Lagrange polynomials, the element type, and the temporal discretization method. In contrast, the memory-saving ratios of the conventional method versus our method is at least N when using either quadrilateral or hexahedron elements, respectively, where N is the order of the Lagrange polynomials used in the SEM. A higher memorysaving ratio is achieved with triangular elements versus quadrilaterals. The new method is applied to reverse time migration by considering the Marmousi model as a benchmark. Numerical results demonstrate that the method is able to provide the same result as the conventional method but with about 1/25 times lower storage demand. With the proposed wavefield reconstruction method, the storage demand is dramatically reduced;therefore, in-core memory storage is feasible even for large-scale three-dimensional adjoint inversion problems. | YouShan Liu Tao Xu YangHua Wang JiWen Teng José Badal HaiQiang Lan | 2019 | Earth and Planetary Physics2019，3，4： | 2 |
| 3 | Ray tracing of turning wave in elliptically anisotropic media with an irregular surface显示文摘Seismic ray tracing in anisotropic media with irregular surface is crucial for the exploration of the fine crustal structure. Elliptically anisotropic medium is the type of anisotropic media with only four independent elastic parameters. Usually, this medium can be described by only the vertical phase velocity and the horizontal phase velocity for seismic wave propagation. Model parameterization in this study is described by flexible triangular grids,which is beneficial for the description of irregular surface with high degree of approximation. Both the vertical and horizontal phase velocities are defined in the triangular grids, respectively, which are used for the description of phase velocity distribution everywhere in the model by linear interpolation. We develop a shooting ray tracing method of turning wave in the elliptically anisotropic media with irregular surface. Runge-Kutta method is applied to solve the partial differential equation of seismic ray in elliptically anisotropic media. Linearly modified method is used for adjusting emergent phase angles in the shooting scheme. Numerical tests demonstrate that ray paths coincide well with analytical trajectories in transversely homogeneous elliptically anisotropic media. Seismic ray tracing results in transversely inhomogeneous elliptically anisotropic media demonstrate that our method is effective for further first-arrival tomography in elliptically anisotropic media with an irregular surface. | Minghui Zhang Tao Xu Zhiming Bai Youshan Liu Jue Hou Guiping Yu | 2017 | Earthquake Science2017，30，5： | 1 |
| 4 | Homeodomain proteins POU-M2, antennapedia and abdominal-B are involved in regulation of the segment-specific expression of the clip-domain serine protease gene CLIP13 in the silkworm, Bombyx mori显示文摘Clip-domain serine proteases (CLIPs) play important roles in insect innate immunity and development. Our previous studies indicated that CLIP13, an epidermis-specific gene, was involved in cuticle remodeling during molting and metamorphosis in the silkworm, Bombyx mori. However, the transcriptional regulatory mechanism and regulatory pathways of CLIP13 remained unclear. In the present study, we investigated CLIP13 expression and the regulation pathway controlled by 20-hydroxyecdysone (20E) in the silkworm. At the transcriptional level, expression of CLIP13 exhibited pronounced spatial and temporal specificity in different regions of the epidermis;homeodomain transcription factors POU-M2, antennapedia (Antp), and abdominal-B (Abd-B) showed similar expression change trends as CLIP13 in the head capsule, thorax, and abdomen, respectively. Furthermore, results of cell transfection assays, electrophoretic mobility shift assays, and chromatin immunoprecipitation demonstrated that POU-M2, Antp, and Abd-B were involved in the transcriptional regulation of CLIP13 by directly binding to their cis-response elements in CLIP13 promoter. RNA interference-mediated silencing of POU-M2, Antp, and Abd-B led to a decrease of CLIP13 expression in the head capsule, the epidermis of the 1st to 3rd thoracic segments and the 7th to 10th abdominal segments, respectively. Consistent with CLIP13, 20E treatment significantly upregulated expression of POU-M2, Antp, and Abd-B in the silkworm epidermis. Taken together, these data suggest that 20E positively regulates transcription of CLIP13 via homeodomain proteins POU-M2, Antp, and Abd-B in different regions of the silkworm epidermis during metamorphosis, thus affecting the molting process. Our findings provide new insight into the functions of homeodomain transcription factors in insect molting. | Huawei Liu Jingya Heng Luoling Wang Youshan Li Xin Tang Xuan Huang Qingyou Xia Ping Zhao | 2022 | Insect Science2022，29，1： | 0 |
| 5 | Multiple phases analysis of deep seismic sounding records in North China Craton显示文摘The North China Craton(NCC)is a key region to study the destruction of the ancient craton.Two groups of phases(denoted as'Pw1'and'Pw2'),which are parallel to the PmP phase reflected from the Moho discontinuity and the PLP phase reflected from the Lithosphere and Asthenosphere Boundary(LAB)respectively,are found on the record section of the Rongcheng-XinzhouAlxa long-range deep seismic sounding profile.The nature of the two phases is still unclear,although they are clearly observable and reverberant.In this paper,we use travel time inversion and amplitude forward modelling to fit the reflected and refracted phases in the lithosphere.The results show:(1)the Pw1 is a multiple reflected phase which is successively reflected by the crystalline basement,the surface,the Moho and then finally received on the surface;(2)the Pw2 phase is also a multiple reflected phase successively reflected by the crystalline basement,the surface,the LAB interface and then received on the surface.We conclude that the significant velocity difference between the thick sedimentary cover and the crystalline basement in the North China rifted basin may be the main reason for generating the multiple reflections.Furthermore,the two multiple reflections provide potent constraints on the lithospheric velocity model,and constitute seismological evidence for the lithospheric thinning in the eastern NCC. | Xiaoqing Zhang Jiyan Lin Minghui Zhang Zhi Liu Baofeng Liu Youshan Liu Tao Xu Zhiming Bai | 2020 | Earthquake Science2020，33，1： | 0 |
| 6 | Soft-template synthesis of hierarchically porous structured polydimethylsiloxane toward flexible capacitive pressure sensor显示文摘Flexible pressure sensors play an important role in the field of monitoring, owing to their inherent safety and the fact that they are embedded at the material level. Capacitive pressure sensors have been proven to be quite versatile, with the ability to change the sensitivity and monitoring range by modifying the pore structure of the dielectric layer(elastic modulus). In this paper, capacitive pressure sensors are devised, comprising hierarchical porous polydimethylsiloxane. Due to the inherent hollow and hierarchical micropore structure, the capacitive pressure sensor allows operation at a wider pressure range(~1000 kPa) while maintaining sensitivity(6.33 MPa-1) in the range of 0–300 k Pa. Subsequently, the capacitance output model of the sensor is optimized, which provides an overall approximation of the experimental values for the sensor performance. Additionally, the signal response of the“break up the whole into parts”(by analysis of the whole sensor in parts) is simulated and outputted by the finite element analysis. The simplified analysis model provides a good understanding of the relationship between the local pressure and the signal response of the pressure sensor. For practical applications, seal monitoring and rubber wheel pressure array system are tested, and the proposed sensor shows sufficient potential for application in large deformation elastomer products. | HE ShiXue WU Jian DUAN YanHao SU BenLong LIU ShouYao TENG Fei WANG YouShan | 2023 | Science China(Technological Sciences)2023，66，9： | 0 |
| 7 | Evaluation of the CAM and PX Surface Layer Parameterization Schemes for Momentum and Sensible Heat Fluxes Using Observations显示文摘In this study,the performances of the Community Atmosphere Model(CAM)and Pleim–Xiu(PX)surface layer parameterization schemes are investigated by using field observations.The parameterization schemes are evaluated against continuous momentum and sensible heat flux observations measured at two flat and homogeneous grassland sites in the suburb of Nanjing,eastern China.The observations were conducted from 30 December 2014 to 18 April 2017 at Jiangxinzhou and from 9 February 2015 to 26 March 2018 at Jiangning.It is found that the momentum flux is overall in good agreement with the observation,and the sensible heat flux is overestimated.The parameterizations of the momentum and sensible heat fluxes well capture the diurnal and seasonal patterns seen in the observations at the two sites.At Jiangxinzhou,the PX parameterization underestimates the momentum flux throughout the day and the CAM parameterization slightly overestimates it around the noon,while they underestimate the momentum flux throughout the year.The two parameterizations overestimate the sensible heat flux in the daytime as well as over the entire year.At Jiangning,the two parameterizations overestimate the momentum flux throughout the day and the sensible heat flux in the daytime,and overestimate both of them over the entire year.The two parameterizations are not significantly different from each other in reproducing the turbulent fluxes at the same site,while they perform differently at the two sites in terms of statistics.In addition,the parameterized fluxes increase with increased roughness length. | Youshan JIANG Dongqing LIU Gang LIU | 2018 | Journal of Meteorological Research2018，32，6： | 0 |
| 8 | SYNTHESIS OF TiN FILM WITH ION BEAM ENHANCED DEPOSITION AND ITS PROPERTIES显示文摘The TiN films were synthesized with an alternate process of depositing titanium from a E-gunevaporation source and 40 keV N^+ bombarding onto the target.It is shown from the composi-tion analysis and structure investigations using RBS,AES,TEM,XPS and X-ray diffractionspectrum that the formed fihns are mainly composed of TiN phase with grain size of 30—40nm and without preferred orientation,the nitrogen content in the film is much less than that incase without N^+ bombarding,and an intermixed region about 40 nm thick exists between thefilm and the substrate.The films exhibt high microhardness and low friction. ZHOU Jiankun,Ion Beam Laboratory,Shanghai Institute of Metallurgy,Academia Sinica,Shanghai 200050。 | ZHOU Jiankun LIU Xianghuai CHEN Youshan WANG Xi ZHENG Zhihong HUANG Wei ZOU Shichang Shanghai Institute of Metallurgy,Academia Sinica,Shanghai,China | 1990 | Acta Metallurgica Sinica(English Letters)1990，3，11： | 0 |
| 9 | New Equations for Describing Contact Area between Tire and Ground显示文摘New equations are proposed to describe the shapes and sizes of the contact areas between tire and ground(the contact areas)under the conditions of static load,slip,camber,and rolling.The equations are super ellipse and trigonometric function with four parameters.Results indicate that the contact areas under the conditions of static load,slip,camber can be well described by super ellipse,in the most complicated case,fourteen parameters are used.The rolling contact area can be reconstructed by the trigonometric function completely.Symmetrical and asymmetrical shapes can both be described perfectly.The suggested curves will make calculate size of the areas easily.The described shapes and sizes are in good agreement with the measured,the maximum deviation is only 2.88%.This work will provide an instrument for understanding the contact area and be helpful for analyzing tire and road. | CUI Zhibo SU Zhaoqian HOU Dandan ZHANG Chunsheng WANG Youshan LIU Yuyan WU Jian | 2020 | 橡胶工业2020，67，9： | 0 |
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