Hot spots in nuclei by microscopic transport theory

In a previous publication effects of two-body collisions were incorporated with TDHF by the time-relaxation method. This microscopic model is now used to study decays of hot spots in nuclei. Calculations are made in a one-dimensional slab geometry. A temperature-dependent expression is used for the relaxation time. It is based on Tomonaga's formula for heat conduction at low temperatures. At high temperatures we use (recent) calculations of imaginary optical potential and equilibration with penetrating infinite nuclear slabs. Our calculations show pre-equilibrium emission of nucleons. This emission is in general decreased by two-body collisions. Some of our results are presented by contour plots of the Wigner function.     

宽谱段红外消热差光学系统设计

宽谱段红外光学系统可以获取宽谱段的图像信息并增大目标信息获取程度。从红外光学系统的简洁性出发,对红外光学系统进行设计,系统仅由4片球面透镜组成,实现了4.4 m~8.8 m波段清晰成像, F#为2.68,达到了100%的冷光阑效应。采用被动消热差方式通过合理选择镜片材料及公式推导最终实现了各个波段内的消热差,镜筒材料为钛合金,透镜采用硒化锌（ZnSe）,锗（Ge）及硫化锌（ZnS）材料,给出20 lp/mm处系统在各个波段在-40 ℃~60 ℃的工作温度下的调制传递函数（MTF）,以及各个波段下的光学系统畸变值。实验结果表明:设计的宽谱段红外光学系统结构简单,满足设计要求。     

长焦距小型无热化电视光机系统设计

针对长焦距小型化电视的设计要求,采用摄远型光学结构压缩系统的轴向尺寸,使摄远比达到了0.53,并对系统进行了消杂光及光机无热化设计,通过合理地设置光阑减少系统的杂散光,选择合适的结构材料与光学材料相匹配,在整个工作温度范围（-40 ℃～+65 ℃）,像面漂移量在焦深范围内,20 lp/mm时系统的MTF在0.7以上,点列斑4.7 m,小于探测器的像元尺寸6 m,光轴稳定性达到了0.04 mrad,系统无需调焦便可满足高低温等恶劣环境下的像质和光轴稳定性要求。试验结果表明:探测和识别特定目标距离均达到了指标要求。     

Hot spots and pseudogaps for hole- and electron-doped high-temperature superconductors

Using cluster perturbation theory, it is shown that the spectral weight and pseudogap observed at the Fermi energy in recent angle resolved photoemission spectroscopy of both electron- and hole-doped high-temperature superconductors find their natural explanation within the t-t(')-t(")-U Hubbard model in two dimensions. The value of the interaction U needed to explain the experiments for electron-doped systems at optimal doping is in the weak to intermediate coupling regime where the t-J model is inappropriate. At strong coupling, short-range correlations suffice to create a pseudogap, but at weak-coupling long correlation lengths associated with the antiferromagnetic wave vector are necessary.     

A catadioptric infrared dual band optically passive athermal optical system

The paper proposes a catadioptric infrared dual band optical system based on catadioptric configuration and optically passive athermal design method. The system shares primary mirror, secondary mirror and collimating lens group, and achieves abruption in longwave infrared and midwave infrared using a dichroic beam splitter. The influence of temperature on optical parameters, the design theory and design method are analyzed. A design example is presented. The detailed optimization design method and some considering factors in engineering design moment are discussed. The design results illustrate that the system can obtain good image quality in environment temperature of 10–40?°C, which could satisfy the design requirement. The actual test result not only satisfies the design requirement, but also validates the availability of the method in the paper.     

Aberration athermal design for infrared search and trace optical system

To satisfy environment requirement of infrared search and trace optical system, an infrared diffractive/refractive hybrid optical system in 3.7–4.8 μm with 11.42° of field of view for passive athermalization is presented. The system is consisted of three lenses, including two aspheric surfaces and a diffraction surface, which has only two materials Ge and Si. The optical system has compact structure, small volume and light weight. The image quality of the system approaches the diffraction limit in the temperature range −80 °C to 160 °C. It is compatible with staring focal plane array which has a format of 320 × 240 and the pixel pitch of 30 μm. The system need not move the compensated lens repeatedly to obtain the best images from −80 °C to 160 °C and enhances the performance of target tracking and recognition.     

“Hot spots” in the field of internal waves in the ocean

A review of observations of high-amplitude internal waves is presented. These waves play an important role in the global scenario of water mixing in the world ocean and also cause a considerable variability of oceanographic fields, including the sound velocity field. The main sources of intense internal waves and the regions where such waves arise are considered. It is shown that, in addition to the much-investigated trains of soliton-like internal waves, which are formed near large-scale inhomogeneities of the bottom relief because of the nonlinear evolution of internal tides, internal waves encountered in the open ocean also possess considerable amplitudes and nonlinearity.     

基于长波红外探测器的消热差轻量化光学系统设计

利用硫系玻璃与二元衍射面设计一款基于12 μm非制冷长波红外探测器(1 024×768 pixel)的红外消热差系统.该系统由3片玻璃构成,焦距为75 mm,F数为1,系统总长97 mm,系统总质量203 g.利用ZEMAX进行仿真分析,仿真结果表明:在?40 ℃～50 ℃温度范围内,系统奈奎斯特频率(42 lp/mm...     

Hot spots enriched plasmonic nanostructure-induced random lasing of quantum dots thin film

Here,a plasmon-enhanced random laser was achieved by incorporating gold nanostars(NS) into disordered polymer and Cd Se/Zn S quantum dots(QDs) gain medium films,in which the surface plasmon resonance of gold NS can greatly enhance the scattering cross section and bring a large gain volume.The random distribution of gold NS in the gain medium film formed a laser-mode resonator.Under a single-pulse pumping,the scattering center of gold NS-based random laser exhibits enhanced performance of a lasing threshold of 0.8 m J/cm~2 and a full width as narrow as 6 nm at half maximum.By utilizing the local enhancement characteristic of the electric field at the sharp apexes of the gold NS,the emission intensity of the random laser was increased.In addition,the gold NS showed higher thermal stability than the silver nanoparticles,withstanding high temperature heating up to 200?C.The results of metal nanostructures with enriched hot spots and excellent temperature stability have tremendous potential applications in the fields of biological identification,medical diagnostics,lighting,and display devices.     

Driven alloys in the athermal limit

Static molecular simulations of binary alloys under extrinsic forcing show that complex ordered or segregated structures may evolve even in the absence of thermally activated diffusion. This result is in opposition to the standard theoretical framework for so-called "driven alloys," which assumes that extrinsic driving is an ideally randomizing process, and therefore predicts only random atomic configurations in the athermal limit. We propose a qualitative modification to the theory that introduces a new control parameter and use additional Monte Carlo simulations to demonstrate the physical plausibility of this modification. New research directions in nonequilibrium dynamic systems are also suggested by this analysis.     

中波红外折衍光学系统消热差设计与杂光分析

论述了红外折衍混合消热差光学系统的设计原理与方法,利用衍射光学元件特性进行消热差与色差,设计出工作波段为3.5μm~5.2μm、F数为2、焦距为100 mm、全视场角7,°具有100%冷屏效率的折衍混合消热差光学系统。对系统进行杂光分析,理想成像光线的像面辐照度为1.5×104W/m2,其他非成像光线的像面辐照度为2 W/m2。该系统在-50℃~80℃的温度范围内成像质量接近衍射极限,适用于像元尺寸为30μm、像元数320×256的致冷型红外焦平面阵列探测器。     

Jamming and crystallization in athermal polymer packings

Dense packings of chains of hard spheres possess characteristic features that do not have a counterpart in corresponding packings of monomeric spheres especially near the maximally random jammed (MRJ) state. From the modelling perspective the additional requirement that spheres keep their connectivity while maximizing the occupied volume fraction imposes severe constraints on generation algorithms of dense chain configurations. The extremely sluggish dynamics imposed by the uncrossability of chains precludes the use of deterministic or stochastic dynamics to generate all but dilute polymer packings. As a viable alternative, especially tailored chain-connectivity-altering Monte Carlo (MC) algorithms have been developed that bypass this kinetic hindrance and have actually been able to produce packings of hard-sphere chains in a volume fraction range spanning from infinite dilution up to the MRJ state. Such very dense athermal polymer packings share a number of structural features with packings of monomeric hard spheres, but also display unique characteristics due to the constraints imposed by connectivity. We give an overview of the most relevant results of our recent modeling work on packings of freely-jointed chains of tangent hard spheres about the MRJ state, local structure, chain dimensions and their scaling with density, topological constraints in the form of entanglements and knots, contact network at jamming, and entropically driven crystallization.     

含有双层衍射光学元件的中波/长波消热差光学系统的设计

建立了工作在一定入射角度范围内的多层衍射光学元件的复合带宽积分平均衍射效率的分析模型。基于衍射光学元件所具有的独特的消色差和消热差性质,设计了一个含有双层衍射光学元件的工作在(3.7~4.8) μm和(7.7~9.5) μm红外双波段光学系统。光学系统的焦距为200 mm,F#为2。采用像元数为320×256、间距为30 μm的制冷型探测器。该系统在空间频率17 lp/mm时,中、长波红外MTF分别高于0.66和0.54;最大RMS半径小于11.702 μm;波前像差小于0.191 7λ;最大离焦量小于焦深;在-55℃~71℃范围内实现了无热化设计。入射到衍射面上的角度为0°~5.19°,该双层衍射光学元件在中波和长波波段的复合带宽积分平均衍射效率分别为99.81%和97.36%。含有双层衍射光学元件的红外双波段光学系统结构简单,像质优良,可以广泛应用于军事探测系统中。     

Time-resolved X-ray spectroscopy of hot spots in an X-pinch

The plasma parameters in hot spots of an X-pinch are determined by using time-resolved data from X-ray spectroscopy in experiments on the implosion of crossed Ti wires in the XP device with a current of 480 kA and pulse duration of 100 ns. The electron densities and temperatures calculated from these data are in the ranges (0.8–3)×10²³cm^–3 and 1–2.5 keV, respectively. An analysis performed shows that the plasma processes are highly nonequilibrium.     

Prewetting and layering in athermal polymer solutions

Coexistence conditions for prewetting and layering at a hard surface in additive hard sphere polymer solutions, where the solvent particles are smaller than the monomers, have been calculated by density functional methods. Various chain lengths and pressures have been investigated. An unexpected finding is that prewetting in these systems may proceed below the bulk critical pressure. We rationalize this behavior in terms of local properties of the pressure tensor. For longer chains, a different behavior is observed where the systems display a lower wetting pressure, i.e., a low pressure bound for surface wetting.     

Surface-induced first-order transition in athermal polymer-nanoparticle blends

We investigate the phase behavior of athermal polymer-nanoparticle blends near a substrate. We apply a recent fluids density functional theory of Tripathi and Chapman to a simple model of the blend as a mixture of hard spheres and freely jointed hard chains, near a hard wall. We find that there is a first-order phase transition in which the nanoparticles expel the polymer from the surface to form a monolayer. The nanoparticle transition density depends on the length of the polymer and the overall bulk density of the system. The effect is due both to packing entropy effects related to size asymmetry between the components and to the polymer configurational entropy. The simplicity of the system allows us to understand the so-called "entropic-push" observed in experiments.