ICF装置靶场结构总体稳定性设计

 通过分析光学元件的动力学响应,计算靶场每条光路的结构漂移误差,进行了靶场结构总体稳定性评估。神光主机装置单光路靶场结构漂移误差计算结果表明：其靶场结构设计满足稳定性要求,该方法可以应用在ICF装置靶场结构总体稳定性设计中,但所得的漂移误差的裕度应大于一个给定的合理值。     

Structural stability, phase transformations and band-tuning of actinide and rare earth based intermetallics under high pressure: a perspective

When a solid is subjected to external pressure, it can undergo either structural transformation or remain stable in its parent structure. The sequence of structural transformations, when mapped for similar materials, viz., isostructural, isoelectronic and so on, can be used to create a map showing the evolution of structures under pressure for such materials. Such maps are useful in predicting high pressure phases. The structural transitions and the stability of materials as a function of pressure are intricately connected to their electronic structure. Many a times it is advantageous to know the stability of the material under pressure just by calculating its electronic structure. This can be accomplished only if several homologues materials are studied and the stability criteria arrived at by correlating their electronic structure with their structural stability under pressure. Further, as a function of pressure, the electronic structure changes can lead to enhancement in certain desired electronic, physical or mechanical properties. Several examples are known, wherein, pressure tuning of the band structure leads to improved properties. In this paper, we have discussed the above mentioned areas and presented a perspective of the above using the results of our own studies on f-electron based intermetallics (f-IMCs).     

神光-Ⅲ主机装置靶场光传输系统结构设计

系统介绍了神光-Ⅲ主机装置靶场光传输系统的结构设计,光传输系统的关键性能包括稳定性、精确性及洁净性,为保证苛刻的稳定性要求,提高结构动力学稳定性的同时提出一种新的稳定性分析方法;通过设计在线可更换单元、运动学支承结构和采用低应力夹持技术实现在线精密调节和快速安装定位;同时在设计、制造和安装过程中建立洁净理念。目前安装完成的束组的测试结果表明,主机装置靶场光传输系统的结构设计满足装置设计要求。     

AEROELASTIC OSCILLATIONS OF A SEESAW-TYPE OSCILLATOR UNDER STRONG WIND CONDITIONS

This paper is concerned with one-degree-of-freedom aeroelastic oscillations of a seesaw- type structure in a steady wind flow. Here it is assumed that strong wind conditions induce nonlinear aeroelastic stiffness forces that are of the same order of magnitude as the structural stiffness forces. As a model equation for the aeroelastic behaviour of the seesaw-type structure, a strongly nonlinear self-excited oscillator is obtained. The bifurcation and the stability of limit cycles for this equation are studied using a special perturbation method. Both the case with linear structural stiffness and the case with nonlinear structural stiffness are studied. For both cases is assumed a general cubic approximation to describe the aerodynamic coefficient. Conditions for the existence, the stability, and the bifurcation of limit cycles are given.     

Robust and Flexible Colloidal Photonic Crystal Films with Bending Strain–Independent Structural Colors for Anticounterfeiting

Colloidal photonic crystals (PCs) possess iridescent and metallic structural color, making them an attractive candidate for anticounterfeiting. However, traditional colloidal PC-based anticounterfeiting materials usually have bending-induced color-switching characteristics or poor flexible stability, significantly affecting their color reproducibility and durability. Here, a novel robust colloidal PC film with bending strain–independent structural color and high flexible stability has been developed through the self-assembly of SiO₂ particles into the poly(ethylene glycol) diacrylate (PEGDA) matrix. The unique microstructure of the colloidal PC film contains ordered and disordered arrays of SiO₂ nanoparticles embedded into the flexible PEGDA matrix, which is crucial to achieving bending strain–independent structural color. In fact, during the bending process, the colorless disordered arrays act as the buffer space, avoiding deformation of the colored ordered arrays and thus maintaining its original structural color. Remarkably, the film retains its structural and optical integrity after 10 000 times bending, supporting its high flexible stability and robustness. In addition, the film shows high transparency so that it can easily achieve an invisible and visible state transition under switch of weak and strong light. The film is potentially useful for applications in anticounterfeiting and encryption.     

铁基非晶稀土合金的结构转变和结构弛豫

通过对铁基非晶稀土合金结构转变和结构弛豫过程特征的研究，讨论了该材料的稳定性；认为稀土成份是影响合金品质和应用前景的关键因素。     

VIBRATION AND STABILITY CONTROL OF SMART COMPOSITE ROTATING SHAFT VIA STRUCTURAL TAILORING AND PIEZOELECTRIC STRAIN ACTUATION

A dual approach based on both structural tailoring and piezoelectric strain actuation, aimed at controlling the free vibration and stability of a spinning circular shaft subjected to axial forces is presented. Due to the involvement in these structural systems of gyroscopic forces and, consequently, of the possible occurrence of divergence and flutter instabilities, the dual control methodology shows a high degree of efficiency toward postponement of the occurrence of these instabilities. The structural model of the shaft as considered in this paper is based on an advanced thin-walled beam that includes the effects of transverse shear, anisotropy of constituent materials, rotatory inertias, etc. The displayed results reveal the synergistic implications of the application of this dual technology toward the enhancement of the dynamic response characteristics and expansion of the domain of stability of these systems.     

Strategies to curb structural changes of lithium/transition metal oxide cathode materials & the changes' effects on thermal & cycling stability

Structural transformation behaviors of several typical oxide cathode materials during a heating process are reviewed in detail to provide in-depth understanding of the key factors governing the thermal stability of these materials. We also discuss applying the information about heat induced structural evolution in the study of electrochemically induced structural changes. All these discussions are expected to provide valuable insights for designing oxide cathode materials with significantly improved structural stability for safe, long-life lithium ion batteries, as the safety of lithium-ion batteries is a critical issue; it is widely accepted that the thermal instability of the cathodes is one of the most critical factors in thermal runaway and related safety problems.     

车载光学平台双层隔振系统设计与试验研究

 分析了冲击、振动对车载精密光学系统的影响,指出了光学平台的变形和振动是影响车载精密光学系统精度和稳定性的主要因素,提出了车载光学平台双层隔振系统的设计方案。采用ANSYS有限元方法分析了光学平台隔振系统的振动模态和减振比,完成了车载状况下的光学平台振动测试。分析与测试结果表明,车载光学平台的双层隔振结构具有良好的稳定性,且对环境强振动有很好的衰减作用。该双层隔振技术方案及其分析测试方法,对于各种车载精密光学系统和设备具有重要的工程应用价值。     

Structural stability and theoretical strength of the single crystal Ag under uniaxial loading

The structural stability and theoretical strength of FCC crystal Ag under uniaxial loading have been investigated by combining MAEAM with Wang modified Born stability criteria. The results reveal that, under sufficient compression, there exists a stress-free BCC phase, which is unstable and slips spontaneously to a stress-free mBCT phase by consuming internal energy. The stable region ranges from −2.076 to 4.390 GPa in the theoretical strength or from −7.972% to 8.721% in the strain correspondingly. The calculated structural energy difference between the BCC and FCC phase is in good agreement with the experimental value.     

On the Stability Behaviour of Boltzmann's Equation

The Boltzmann equation for an “isolated” gas system is assumed to form a “dynamical system” in a compact subset of the space of continuous distribution functions (existence assumption). Then the asymptotic stability in the sense of Lyapunov of the total Maxwell distribution is investigated (“approach to equilibrium”). Further the influence of persistent perturbations on the stability behaviour of Boltzmann's equation is considered (“structural stability”).     

L12型铝合金的结构、弹性和电子性质的第一性原理研究

运用第一性原理方法研究了L12型铝合金相Al3Sc和Al3Zr的晶体结构、电子结构和弹性.结合能和形成能的计算表明,两种合金具有较强的合金化能力,且Al3Zr较Al3Sc具有更强的结构稳定性.电子结构分析表明,费米能级以下较多的价电子数决定了Al3Zr具有较强的结构稳定性.计算并分析比较了两种合金相的单晶弹性常数(C11,C12和C44)以及多晶弹性模量(体弹性模量B、剪切模量G、杨氏模量Y、泊松比ν和各向异性因子A).通过对比实验和其他理论计算结果,进一步分析和解释了两种合金相的力学性质.     

Effect of helium ion irradiation on the structure and electrical resistivity of nanocrystalline Cr–N and V–N coatings

The structural stability and electrical resistivity of nanocrystalline Cr–N and V–N coatings prepared by ion beam-assisted deposition were studied. The results showed that under helium ion irradiation up to doses of 1.0^.10¹⁷ ion/cm² the fine-crystalline objects successively increase their resistance without apparent structural changes. The subsequent dose increase leads to gas-vacancy void formation and chromium nitride structure destruction. The presence of the initial closed porosity in vanadium nitride favors its structural stability at investigated maximum damage doses.     

Velocities of sound and the densities of phonon states in a uniformly strained flat graphene sheet

The effect of elastic strain on the mechanical and physical properties of graphene has been intensively studied in recent years. Using the molecular dynamics method, a surface has been built in the three-dimensional space of components of the plane strain tensor bounds the region of the structural stability of a flat graphene sheet without considering thermal vibrations and the influence of boundary conditions. The velocities of sound and the densities of phonon states in graphene subjected to an elastic strain within the region of the structural stability have been calculated. It has been shown that one of the velocities of sound becomes zero near the stability boundary of a flat graphene sheet. During biaxial tension of graphene, there is no gap in its phonon spectrum; however, it forms under uniaxial tension along the zigzag or armchair directions and also under combined tensile and compressive strains.     

光谱法研究细胞色素c氧化酶CuA结构域蛋白的稳定性

利用荧光光谱和圆二色谱研究了细胞色素c氧化酶CuA结构域蛋白的稳定性.结果表明,随着溶液pH值的升高,CuA结构域蛋白的稳定性降低.随着温度的升高,CuA结构域蛋白的二级结构遭到破坏.脱金属形式蛋白的热稳定性减小,表明双核金属铜中心的存在对CuA结构域蛋白的稳定性起重要作用.     

Infrared spectroscopy and ultrasonic velocimetry as a tool for probing conformational flexibility of proteins

Abstract

Because of the crucial importance of structural fluctuations for function and stability of proteins, there is a strong interest for the relationships between structural fluctuations, the parameters of protein denaturation and the kinetics of H/D-exchange. Structural fluctuations can be described by volume and entropy fluctuations and these quantities are accessible via the isothermal compressibility, the thermal expansion and the isobaric heat capacity.

Our aim is to present the principal problem concerning the experimental procedures to answer those questions using lysozyme and α-lactalbumin. Whereas the transition parameters and the kinetics of the H/D-exchange were obtained using FTIR spectroscopy, the adiabatic compressibility was obtained by a combination of ultrasonic velocimetry and densitometry. It could be shown that the stability of the investigated proteins is correlated with reduced volume fluctuations. The expected direct correlation between H/D exchange rates and structural fluctuations could not be seen and it is assumed that the interactions are more complex than from the intuitive point of view.     

Role of interaction anisotropy in the formation and stability of molecular templates

Surface templating via self-assembly of hydrogen-bonded molecular networks is a rapidly developing bottom-up approach in nanotechnology. Using the melamine-PTCDI molecular system as an example we show theoretically that the network stability in the parameter space of temperature versus molecular coupling anisotropy is highly restricted. Our kinetic Monte Carlo simulations predict a structural stability diagram that contains domains of stability of an open honeycomb network, a compact phase, and a high-temperature disordered phase. The results are in agreement with recent experiments, and reveal a relationship between the molecular size and the network stability, which may be used to predict an upper limit on pore-cavity sizes.     

On Exponential-Asymptotic Stability Properties of BOLTZMANN's Equation and a Class of its Modifications

For the linearized BOLTZMANN equation and a class of “modifications” of the linearized BOLTZMANN equation (including the usual BOLTZMANN equation) exponential-asymptotic stability of the total equilibrium is proved with respect to some boundary and existence assumptions which seem to be physically reasonable. Of course, this structural stability is important if BOLTZMANN 's equation has to be considered under the influence of “perturbations” or if it is substituted by model equations.     

Preservation of stability and synchronization in nonlinear systems

Preservation of stability in the presence of structural and/or parametric changes is an important issue in the study of dynamical systems. A specific case is the synchronization of chaos in complex networks where synchronization should be preserved in spite of changes in the network parameters and connectivity. In this work, a methodology to establish conditions for preservation of stability in a class of dynamical system is given in terms of Lyapunov methods. The idea is to construct a group of dynamical transformations under which stability is retained along certain manifolds. Some synchronization examples illustrate the results.     

差动柔性绳传动惯性稳定平台载荷分析与结构校核

针对一种新型柔索传动差动结构稳定平台结构设计问题,开展平台载荷分析和框架结构强度以及稳定性校核研究。根据平台的实际工况和载荷特点,将载荷划分为惯性载荷、质心偏移加速度载荷、摩擦载荷和环境载荷,分类计算并进行载荷综合和功率估算;以回转架结构为例进行结构静动态校核,根据载荷分析结果,对框架结构进行有限元分析,校核结果显示回转架具有良好的静动态特性:平台框架调转及随载体机动过程中的变形在系统允许的范围之内,满足设计要求;框架结构一阶固有频率为156.04 Hz,远高于伺服系统工作带宽,不会引起谐振,具有较高的结构动态稳定性。