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Search Results: 1 - 10 of 120247 matches for " Jincheng Wang "
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Furstenberg Families and Sensitivity
Huoyun Wang,Jincheng Xiong,Feng Tan
Discrete Dynamics in Nature and Society , 2010, DOI: 10.1155/2010/649348
Abstract: We introduce and study some concepts of sensitivity via Furstenberg families. A dynamical system (,) is ?-sensitive if there exists a positive such that for every ∈ and every open neighborhood of there exists ∈ such that the pair (,) is not ?--asymptotic; that is, the time set {∶((),())>} belongs to ?, where ? is a Furstenberg family. A dynamical system (,) is (?1, ?2)-sensitive if there is a positive such that every ∈ is a limit of points ∈ such that the pair (,) is ?1-proximal but not ?2--asymptotic; that is, the time set {∶((),())<} belongs to ?1 for any positive but the time set {∶((),())>} belongs to ?2, where ?1 and ?2 are Furstenberg families.
Finite-Time Combination-Combination Synchronization for Hyperchaotic Systems
Huini Lin,Jianping Cai,Jincheng Wang
Journal of Chaos , 2013, DOI: 10.1155/2013/304643
Abstract: A new type of finite-time synchronization with two drive systems and two response systems is presented. Based on the finite-time stability theory, step-by-step control and nonlinear control method, a suitable controller is designed to achieve finite-time combination-combination synchronization among four hyperchaotic systems. Numerical simulations are shown to verify the feasibility and effectiveness of the proposed control technique. 1. Introduction As a new subject in 1980s, chaos almost covers all the fields of science. It is known that chaos is an interesting nonlinear phenomenon which may lead to irregularity and unpredictability in the dynamic system, and it has been intensively studied in the last three decades. Since Pecora and Carroll proposed the PC method to synchronize two chaotic systems in 1990 [1, 2], the study of synchronization of chaotic systems has been widely investigated due to their potential applications in various fields, for instance, in chemical reactions, biological systems, and secure communication. Over the past decades, a variety of control approaches such as adaptive control [3], linear feedback control [4], active control [5], and backstepping control [6] have been proposed for various types of synchronization, which include complete synchronization [7], projective synchronization [8, 9], general synchronization [10], lag synchronization [11], and novel compound synchronization [12]. Most of the aforementioned works are based on the synchronization scheme which consists of one drive system and one response system and can be seen as one-to-one system. However, we found it not secure and flexible enough in many real world applications, for instance, in secure communication. Recently, Runzi et al. presented a new type of synchronization with two drive systems and one response system [13]. Then, Sun et al. extended multi-to-one system to multi-to-two systems and reported a new type of synchronization, namely, combination-combination synchronization, where synchronization is achieved between two drive systems and two response systems [14]. The type of synchronization can improve the security of communication; for instance, we can split the transmitted signals into several parts, then load each part in different drive systems, and then restore it to the original signals by combining the received signals of different response systems correctly. Notice that the mentioned literatures mainly investigated the asymptotic synchronization of chaotic systems. However, in the view of practical application, optimizing the synchronization
Pairing fluctuation effects in a strongly coupled color superfluid/superconductor
Jinyi Pang,Jincheng Wang,Lianyi He
Physics , 2012, DOI: 10.1103/PhysRevD.88.054017
Abstract: We investigate the effects of pairing fluctuations in fermionic superfluids/superconductors where pairing occurs among three species (colors) of fermions. Such color superfluids/superconductors can be realized in three-component atomic Fermi gases and in dense quark matter. The superfluidity/superconductivity is characterized by a three-component order parameter which denotes the pairing among the three colors of fermions. Due to the SU$(3)$ symmetry of the Hamiltonian, one color does not participate pairing. This branch of fermionic excitation is gapless in the naive BCS mean-field description. In this paper, we adopt a pairing-fluctuation theory to investigate the pairing fluctuation effects on the unpaired color in strongly coupled atomic color superfluids and quark color superconductors. At low temperature, a large pairing gap of the paired colors suppresses the pairing fluctuation effects for the unpaired color, and the spectral density of the unpaired color shows a single Fermi-liquid peak, which indicates the naive mean-field picture remains valid. As the temperature is increased, the spectral density of the unpaired color generally exhibits a three-peak structure: the Fermi-liquid peak remains but get suppressed, and two pseudogap-like peaks appears. At and above the superfluid transition temperature, the Fermi-liquid peak disappears completely and the all three colors exhibits pseudogap-like spectral density. The coexistence of Fermi liquid and pseudogap behavior is generic for both atomic color superfluids and quark color superconductors.
Interface instability modes in freezing colloidal suspensions - revealed from onset of planar instability
Lilin Wang,Jiaxue You,Zhijun Wang,Jincheng Wang,Xin Lin
Physics , 2015,
Abstract: Freezing colloidal suspensions widely exists in nature and industry. Interface instability has attracted much attention for the understandings of the pattern formation in freezing colloidal suspensions. However, the interface instability modes, the origin of the ice banding or ice lamellae, are still unclear. In-situ experimental observation of the onset of interface instability is still absent up to now. Here, by directly imaging the initial transient stage of planar interface instability in directional freezing colloidal suspensions, we proposed three interface instability modes, Mullins-Sekerka instability, global split instability and local split instability. All the three instability modes come from the competition of the solute boundary layer and the particle boundary layer, which only can be revealed from the initial transient stage of planar instability in directional freezing.
Motion Intention Analysis-Based Coordinated Control for Amputee-Prosthesis Interaction
Fei Wang,Shiguang Wen,Chengdong Wu,Yuzhong Zhang,Jincheng Li
Journal of Robotics , 2010, DOI: 10.1155/2010/139634
Abstract: To study amputee-prosthesis (AP) interaction, a novel reconfigurable biped robot was designed and fabricated. In homogeneous configuration, two identical artificial legs (ALs) were used to simulate the symmetrical lower limbs of a healthy person. Linear inverted pendulum model combining with ZMP stability criterion was used to generate the gait trajectories of ALs. To acquire interjoint coordination for healthy gait, rate gyroscopes were mounted on CoGs of thigh and shank of both legs. By employing principal component analysis, the measured angular velocities were processed and the motion synergy was obtained in the final. Then, one of two ALs was replaced by a bionic leg (BL), and the biped robot was changed into heterogeneous configuration to simulate the AP coupling system. To realize symmetrical stable walking, master/slave coordinated control strategy is proposed. According to information acquired by gyroscopes, BL recognized the motion intention of AL and reconstructed its kinematic variables based on interjoint coordination. By employing iterative learning control, gait tracking of BL to AL was archived. Real environment robot walking experiments validated the correctness and effectiveness of the proposed scheme. 1. Introduction Lower limb prosthesis is used to compensate the locomotion function for amputees in the field of biomedical rehabilitation. Conventional mechanical prosthesis has been criticized for difficulty in motion transformation, stiff-legged gait and poor mobility under complex condition. Intelligent prosthetic leg controlled by a microprocessing unit can realize the arbitrary gait precisely to coordinate with the sound leg of amputee [1]. It has been a challenging endeavor for interaction between amputee and prosthesis for their different structures, actuation manners, cognitive competence, and dynamic characters. To realize coordinated movement, prosthetic leg must be able to perceive the motion intention of amputee properly so as to actuate its joints accordingly when walking on different terrains with various cadences and stride length. To guarantee the performance of prosthetic leg during development stage, a great amount of repetitive experiments that need amputee to participate entirely is necessary. It is not only costly but also painful to handicapped person, and even leads to accidental injury to amputee. Moreover, individual difference also makes it difficult to obtain the uniform and quantitative performance evaluation for prosthetic leg. To solve problems mentioned above, a novel reconfigurable test-bed for prosthetic
Look back and look forward to granite research.
我国花岗岩研究的回顾与展望

Wang Dezi,Zhou Jincheng,
王德滋
,周金城

岩石学报 , 1999,
Abstract: Some aspects about domestic granite research since 1980's have been reviewed in the paper , which include the formation and evolution of granites in orogenic belts ,the features of subvolcanic granitoids , the petrogenesis of A type granite , the magma
Preliminary Research on the Relationship between the Analysis Error and Both Sampling Strategies and Sample Content of the Assimilation by Using 4DSVD
4DSVD分析误差与样本选取方法和样本容量的关系初探

Wang Jincheng,Li Jianping,
王金成
,李建平

气候与环境研究 , 2010,
Abstract: 分析误差与样本选取方法和样本容量的关系是4DSVD同化方法一个亟需研究的重要问题。获得支撑大气模式空间和观测空间吸引子的基向量是4DSVD研究的关键部分,样本的好坏和样本容量的范围是决定4DSVD基向量和分析结果质量的一个重要前提条件。首先利用Lorenz 28变量模式,用4DSVD方法做了一些简单三维同化试验,探讨了Lorenz 28变量模式的分析误差与样本容量和样本选取方法的关系。数值试验结果表明,对一个具体的模式,有限的样本容量就能够获得较高精度的分析结果;在模式系统和观测系统不变情况下,用一定样本容量得到的支撑模式空间和观测空间的基向量具有很好的稳定性,即一旦获得一组较好的基向量,在观测系统和模式系统不变的情况下,对同化任何时刻的观测适用;分析结果对选取方法没有太大的依赖性,但具体的样本容量要视不同模式和样本选取方法而定。用WRF模式做的4DSVD四维观测系统模拟试验结果表明,若样本选取方法得当,所需要的样本容量要远远小于模式自由度。4DSVD要真正获得较高精度的分析结果,需要的条件是尽可能的在吸引子上取样并选取充足的样本容量;间隔取样可以一定程度上减少计算量。根据数值试验结果提出了4DSVD在实际同化时样本选取的一些初步的方法。
High-quality reduced graphene oxide-nanocrystalline platinum hybrid materials prepared by simultaneous co-reduction of graphene oxide and chloroplatinic acid
Wang Yinjie,Liu Jincheng,Liu Lei,Sun Darren
Nanoscale Research Letters , 2011,
Abstract: Reduced graphene oxide-nanocrystalline platinum (RGO-Pt) hybrid materials were synthesized by simultaneous co-reduction of graphene oxide (GO) and chloroplatinic acid with sodium citrate in water at 80°C, of pH 7 and 10. The resultant RGO-Pt hybrid materials were characterized using transmission electron microscopy (TEM), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy, and thermogravimetric analysis. Platinum (Pt) nanoparticles were anchored randomly onto the reduced GO (RGO) sheets with average mean diameters of 1.76 (pH 7) and 1.93 nm (pH 10). The significant Pt diffraction peaks and the decreased intensity of (002) peak in the XRD patterns of RGO-Pt hybrid materials confirmed that the Pt nanoparticles were anchored onto the RGO sheets and intercalated into the stacked RGO layers at these two pH values. The Pt loadings for the hybrid materials were determined as 36.83 (pH 7) and 49.18% (pH 10) by mass using XPS analysis. With the assistance of oleylamine, the resultant RGO-Pt hybrid materials were soluble in the nonpolar organic solvents, and the dispersion could remain stable for several months.
Antiangiogenic Effect of Oyster Polypeptide (OPP)
Zhenhua WANG,Jincheng LIU,Ai SU,Mi SUN
Chinese Journal of Lung Cancer , 2009,
Abstract: Background and objective Drugs which block tumor angiogenesis will be likely effective towards inhibiting tumor growth for angiogenesis being a prerequisite for tumor growth and metastasis. Therefore, antiangiogenesis has become a promising strategy for the treatment of cancer. Investigation on both antiangiogenic effect and mechanism(s) of oyster polypeptide (OPP) were performed via experiments of chicken embryos model in vivo and human umbilical vein endothelial cells (HUVECs) in vitro. Methods The methods employed in experiment were chorioallantoic membrane (CAM) angiogenesis in chicken embryos in vivo, MTT cell survival assay, flat plate scarification, transwell plates assay, matrigel-induced tube formation assay and transmission electron microscope et al. and the OPP’s effects on angiogenesis was observed. Results Study showed that treatment with OPP resulted in significant inhibition of chorioallantoic membrane (CAM) angiogenesis in chicken embryos. MTT cell survival assay showed that treatment with OPP resulted in strong inhibition of HUVECs growth, with an IC50 of 400 μg/mL. Flat plate scarification suggested that OPP (200 μg/mL, 400 μg/mL and 800 μg/mL) distinctly inhibited HUVECs’ migration (18.75%, 37.93%, 74.07% respectively, treatment for 12 h). Treatment with OPP of different concentrations (200 μg/mL, 400 μg/mL and 800 μg/mL) significantly reduced the density of the migration cells by 15.5%, 37.2% and 67.24% (P<0.05) respectively. Matrigel-induced tube formation assay showed that OPP resulted in striking inhibition of tube formation of 52.43%, 84.47% and 96.12% (P<0.01) at 200 μg/mL, 400 μg/mL and 800 μg/mL (treatment for 10 h) respectively. In addition, the apoptotic analysis by transmission electron microscope showed that OPP (400 μg/mL, treatment for 48 h) distinctly induced HUVECs’ apoptosis. Conclusion This study strikingly showed that OPP could inhibit angiogenesis through its effects on vascular endothelial cells directly and the inhibition of their proliferation, migration, angiogenic ability, and induction of their apoptosis might be the antiangiogenic mechanism of OPP.
Does the 62-day X-ray periodicity come from ULX M82 X-1?
Yanli Qiu,JiFeng Liu,Jincheng Guo,Jing Wang
Physics , 2015, DOI: 10.1088/2041-8205/809/2/L28
Abstract: M82 X-1 is the brightest ultraluminous X-ray source in starburst galaxy M82 and is one of the best intermediate mass black hole candidates. Previous studies based on the Rossi X-ray Timing Explorer/Proportional Counter Array (RXTE/PCA) reported a regular X-ray flux modulation of M82 with a period of 62 days, and attributed this periodic modulation to M82 X-1. However, this modulation is not necessarily from M82 X-1 because RXTE/PCA has a very poor spatial resolution of ~1 degree. In this work, we analyzed 1000 days of monitoring data of M82 X-1 from the Swift/X-ray telescope (XRT), which has a much better spatial resolution than RXTE/PCA. The periodicity distribution map of M82 reveals that the 62-day periodicity is most likely not from M82 X-1, but from the summed contributions of several periodic X-ray sources 4 arcsec southeast of M82 X-1. However, Swift/XRT is not able to resolve those periodic sources and locate the precise origin of the periodicity of M82. Thus, more long-term observations with higher spatial resolution are required.
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