共查询到20条相似文献,搜索用时 218 毫秒
1.
Crystallization evolution and relaxation behavior of high entropy bulk metallic glasses using microalloying process 下载免费PDF全文
《中国物理 B》2021,30(6):66401-066401
The role of the microalloying process in relaxation behavior and crystallization evolution of Zr_(20) Cu_(20) Ni_(20) Ti_(20) Hf_(20) high entropy bulk metallic glass(HEBMG) was investigated. We selected Al and Nb elements as minor elements, which led to the negative and positive effects on the heat of mixing in the master HEBMG composition, respectively. According to the results, both elements intensified β relaxation in the structure; however, α relaxation remained stable. By using different frequencies in dynamic mechanical analysis, it was revealed that the activation energy of β relaxation for the Nb-added sample was much higher, which was due to the creation of significant structural heterogeneity under the microalloying process. Moreover, it was found that Nb addition led to a diversity in crystallization stages at the supercooled liquid region.It was suggested that the severe structural heterogeneity in the Nb-added sample provided multiple energy-level sites in the structure for enhancing the crystallization stages. 相似文献
2.
Detection of Mechanism of Noise-Induced Synchronization between Two Identical Uncoupled Neurons 下载免费PDF全文
We investigate the noise-induced synchronization between two identical uncoupled Hodgkin-Huxley neurons with sinusoidal stimulations. The numerical results confirm that the value of critical noise intensity for synchronizing two systems is much less than the magnitude of mean size of the attractor in the original system, and the deterministic feature of the attractor in the original system remains unchanged. This finding is significantly different from the previous work [Phys. Rev. E 67 (2003) 027201] in which the value of the critical noise intensity for synchronizing two systems was found to be roughly equal to the magnitude of mean size of the attractor in the original system, and at this intensity, the noise swamps the qualitative structure of the attractor in the original deterministic systems to synchronize to their stochastic dynamics. Further investigation shows that the critical noise intensity for synchronizing two neurons induced by noise may be related to the structure of interspike intervals of the original systems. 相似文献
3.
DOU Fu-Quan SUN Jian-An DUAN Wen-Shan 《理论物理通讯》2008,50(10):907-912
Based on active control theory, anti-synchronization between two different hyperchaotic systems is investigated. The sufficient conditions for achieving anti-synchronization of two different hyperchaotic systems are derived. Moreover, numerical simulations are presented for hyperehaotic Lorenz-Chen system, hyperchaotic Lorenz-Lu system, and hyperchaotic Chen Lu system to verify the effectiveness and feasibility of the proposed anti-synchronization scheme. 相似文献
4.
Synthesis of diamonds in Fe-C systems using nitrogen and hydrogen co-doped impurities under HPHT 下载免费PDF全文
《中国物理 B》2017,(9)
In this study, we investigate the effect of nitrogen and hydrogen impurities on colors, morphologies, impurity structures and synthesis conditions of diamond crystals in Fe–C systems with C_3N_6H_6 additives at pressures in the range 5.0–6.5 GPa and temperatures of 1400–1700℃ in detail. Our results reveal that the octahedron diamond nucleation in a Fe–C system is evidently inhibited by co-doped N–H elements, thereby resulting in the increase of minimum pressure and temperature of diamond synthesis by spontaneous nucleation. The octahedron diamond crystals synthesized from a pure Fe–C system are colorless, while they become green in the system with C_3N_6H_6 additive. The surface defects of diamond will deteriorate when the nitrogen and hydrogen atoms simultaneously incorporate in the diamond growth environment in the Fe–C system. We believe that this study will provide some important information and be beneficial for the deep understanding of the crystallization of diamonds from different component systems. 相似文献
5.
We studied the effect of Coulomb interaction on the isospin fractionation in the intermediate energy heavy ion collisions by using the isospin-dependent quantum molecular dynamics model. The calculated results show that Coulomb interaction induces the reduction of the isospin fractionation process with the evolutions of neutronproton ratio and mass of system. Because Coulomb interaction is repulsive for the proton, more binding protons become free, which produces the neutron-poor gas phase and neutron-rich liquid phase, compared to the neutronproton ratio of the system. The isospin fractionation degree is weakened by the Coulomb term. In contrast, the symmetry potential is repulsive for neutrons and attractive for protons in the neutron-rich system, and then the binding neutrons more than the protons become free, which produces a neutron-rich gas phase and neutron-poor liquid phase, so that the isospin fractionation degree is increased. The competition between the effects from the Coulomb interaction and the symmetry potential induces the reduction of the isospin fractionation degree for all the system masses. The properties for the sensitive dependence of isospin fractionation degree on the symmetry potential and weak dependence on the nucleon-nucleon cross section are preserved for all the neutron-rich systems. 相似文献
6.
A 1550-nm all-fiber monostatic lidar system based on linear chirp amplitude modulation and heterodyne detection for the measurements of range and velocity is presented. The signal processing method is given, after which the relationship between the peak frequency values in the final signal spectrum, the target's range, and the line-of-sight velocity is obtained in the presence of the fiber end-face-reflected signal plaguing many monostatic lidar systems. The range of an electric fan as well as the line-of-sight fan speed of different levels is tested. This proposed system has a potential application for the space-borne landing system. 相似文献
7.
Synchronization between fractional-order chaotic systems and integer orders chaotic systems (fractional-order chaotic systems) 下载免费PDF全文
Based on the idea of tracking control and stability theory of fractional-order systems, a controller is designed to synchronize the fractional-order chaotic system with chaotic systems of integer orders, and synchronize the different fractional-order chaotic systems. The proposed synchronization approach in this paper shows that the synchronization between fractional-order chaotic systems and chaotic systems of integer orders can be achieved, and the synchronization between different fractional-order chaotic systems can also be realized. Numerical experiments show that the present method works very well. 相似文献
8.
BinBin Xiao NaiZhou Wang Chao Shang FanBao Meng JianWen Ding Bin Lei XiGang Luo 《中国科学:物理学 力学 天文学(英文版)》2019,(4)
The origin of the ~40 and ~30 K superconducting phases in the metal-intercalated FeSe superconductors is still unclear. We report the synthesis of K_(0.3)(NH_3)_y(FeSe_(1-x)Te_x)_2 and K_(0.6)(NH_3)_y(FeSe_(1-x)Te_x)_2 with x=0-0.6 by using the liquid ammonia method at room temperature. The superconducting transition temperature Tcof the former remains about 43 K for all the nominal Te content less than 0.3, while that of the latter is about 30 K and obviously decreases with Te doping. Superconductivity disappears for x ≥0.4 in both systems. Except for the different chemical pressure induced by substitution of Te for Se in both systems, we also observed distinct external pressure effect on superconductivity for both systems, with much more efficiency of suppressing Tcby external pressure in the former system. These dramatic differences of both chemical and external pressure effects on Tc between the ~30 and ~40 K superconducting phases revealed that the existence of the two superconducting phases can be ascribed to the moderate and negligible coupling between FeSe layers, respectively. 相似文献
9.
The static and dynamic properties of the two-dimensional classic system of two-species interacting charged particles in a parabolic trap are studied. The ground state energy and configuration for different kinds of binary systems are obtained by Monte Carlo simulation and Newton optimization. The spectrum and normal modes vectors can be gained by diagonalizing the dynamical matrix of the system. It is found that the total particle number, particle number and mass-to-charge ratio of each species are decisive factors for the system structure and spectrum. The three intrinsic normal modes of single species Coulomb clusters are inherent, concluded from our numerical simulations and analytical results. 相似文献
10.
This paper proposes a method of realizing generalized chaos synchronization of a weighted complex network with different nodes. Chaotic systems with diverse structures are taken as the nodes of the complex dynamical network, the nonlinear terms of the systems are taken as coupling functions, and the relations among the nodes are built through weighted connections. The structure of the coupling functions between the connected nodes is obtained based on Lyapunov stability theory. A complex network with nodes of Lorenz system, Coullet system, Rõssler system and the New system is taken as an example for simulation study and the results show that generalized chaos synchronization exists in the whole weighted complex network with different nodes when the coupling strength among the nodes is given with any weight value. The method can be used in realizing generalized chaos synchronization of a weighted complex network with different nodes. Furthermore, both the weight value of the coupling strength among the nodes and the number of the nodes have no effect on the stability of synchronization in the whole complex network. 相似文献
11.
运用基于密度泛函理论的第一性原理分子动力学和静态电子结构计算,研究了La65X35(X=Ni,Al)非晶合金体系原子结构随温度演化的规律及其相关电子结构特性.使用径向分布函数、Voronoi团簇以及键对分析等给出了从高温液体快速冷却到玻璃态过程中原子结构的演化规律.研究发现,该类合金体系的原子排布符合局域密堆模型,两体系中占比最大的特征多面体类型由溶质与溶剂原子半径比调控;两体系中高五次对称性局域结构随温度的下降而增加验证了其在抑制晶化方面的重要作用;利用投影态密度分析两体系电子结构之间的差异,指出La-5d与Ni-3d电子间强烈的杂化是La–Ni 间键长缩短的电子结构起源,为理解成分相关的结构和物性提供了重要线索. 相似文献
12.
建立了在过冷水溶液中传播的光束的非局域非线性模型.过冷水的热致折射率扰动在温度扰动较小的情况下随温度增大,但在温度扰动达到一定程度后随温度减小.在求出该模型的数值孤子解后,对孤子的性态进行了研究.研究表明,在光功率较小时,过冷水表现出自聚焦的特性,而在光功率较大时,在孤子的中心区域的过冷水表现出自散焦的特性,而在孤子的外围仍表现为自聚焦.在总功率较大的情况下,孤子间的相互作用也表现出这种部分自散焦,部分自聚焦的现象. 相似文献
13.
按甲基醚、乙基醚、正丙基醚、异丙基醚和叔丁基醚等五大类,提出了计算链状脂肪醚17O-NMR化学位移的公式:δcal =δ0n+Δα+ Δβ+Δγ,并通过线性回归法结合最小二乘法得到29种取代基的参数,计算结果用以上五大类147种化合物的147个17 O-NMR化学位移数据为样本点作回归检验,置信度为99.5%,计算误差Δδ小于5.0(相对误差小于0.5%)的17O-NMR化学位移计算值约占90%. 相似文献
14.
含羟基化合物的17O-NMR化学位移研究 总被引:15,自引:15,他引:0
在系统地归纳总结前人对含羟基化合物17O-NMR化学位移研究成果的基础上,按伯、仲、叔醇,i-R-OH型化合物(i-R表示与羟基直接相连的原子为非链状烷烃碳原子的取代基)及苯酚类等五大类,提出了计算含羟基化合物17O-NMR化学位移的公式:δcal=δ0+∑aiΔδi,并通过 线性回归法结合最小二乘法得到15种计算醇和羧酸中羟基17O-NMR化学位移时采用的取代基参数和23种计算 酚羟基17O-NMR化学位移时采用的取代基参数,计算结果分别以伯、仲、叔醇、i-R-OH型化合物四类140种化合物和60种酚类在化合物为样本点作回归检验,置信度均为99.5% ,计算误差Δδ小于5(相对误差小于0.5%)的17O-NMR化学位移计算值均在90 %以上. 相似文献
15.
由于缺乏位错、晶界等典型的晶格缺陷,金属玻璃体系中承载力的形变单元为短程序或中程序原子团簇,键的强度及成键方向是影响原子间协调变形能力主要因素.本文通过与晶态合金对比,指出金属玻璃中原子键合方式与宏观力学性能的潜在关系,综述了金属材料电子结构与力学性能内在关系的最新研究进展,并系统介绍了金属玻璃电子结构特征、表征参量和主要测试手段,使读者对金属玻璃体系中原子间的键态特征有较清晰的认识,对进一步探索本征塑性较好的金属玻璃体系具有一定指导意义. 相似文献
16.
分别在298,310,318 K温度下,利用荧光光谱法研究了pH=7.40生理条件下硝基羟乙唑(TRI)与溶菌酶(LYSO)的相互作用机理。结果表明,TRI与LYSO间通过静态猝灭方式相互作用。测定了LYSO与TRI反应的结合常数、结合位点数。利用反应过程的热力学参数,确定了LYSO-TRI体系的作用力类型;由Hill系数得出了LYSO或TRI的协同性;根据非辐射能量转移理论,确定了TRI到LYSO的结合距离,同时采用同步光谱法考察了TRI对LYSO构象的影响。 相似文献
17.
Hubbard R.F. Sprangle P. Hafizi B. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》2000,28(4):1159-1169
Future wakefield accelerator (LWFA) experiments are expected to operate in the short pulse resonant regime and employ some form of laser guiding, such as a preformed plasma channel. Performance of an LWFA may be characterized by the maximum axial electric field Em, the dephasing length Ld, and the corresponding dephasing limited energy gain Wd. Dephasing is characterized by the normalized phase slippage rate Δβp, of the wakefield relative to a particle moving at the velocity of light. This paper presents analytical models for all of these quantities and compares them with results from simulations of channel-guided LWFAs. The simulations generally confirm the scaling predicted by the analytical models, agreeing within a few percent in most cases. The results show that with the proper choice of laser and channel parameters, the pulse will propagate at a nearly constant spot size rM over many Rayleigh lengths and generate large accelerating electric fields. The spot size correction to the slippage rate is shown to be important in the LWFA regime, whereas Δβp, is essentially independent of laser intensity. An example is presented of a 25-TW, 100-fs laser pulse that produces a dephasing limited energy gain in excess of 1 GeV 相似文献
18.
19.
20.
通过引入静水应力对自由体积演化的影响, 研究了金属玻璃在不同温度下的拉压屈服行为. 结果表明, 在拉伸和压缩载荷下, 屈服强度均满足(T/Tg)1/2的温度依赖关系; 同时, 在不同温度下, 材料的压力敏感系数保持为常值0.1. 随着温度的升高, 压力对自由体积的影响逐渐降低, 从而导致材料的拉压屈服不对称性逐渐趋于不显著. 在高温下, 显著的结构弛豫减缓了自由体积增长速率从而抑制材料迅速屈服. 这些结果将有助于更深入的认识金属玻璃屈服及其拉压不对称性的内在机理. 相似文献