激光惯性约束聚变(ICF)玻璃靶丸研究及进展

空心玻璃微球(HGM)在常温常压下对DT气体的渗透率低,机械强度高,在惯性约束聚变靶的制备工艺中是一种常用的DT燃料容器.已经应用于神光I和II系列实验的薄壁玻璃微球,壁厚降到1μm以下,提高了中子产额,并获得内爆特征信息.简要综述了国内外有关惯性约束玻璃靶丸的研究及进展.     

微球状骨修复材料研究

结合自体碎骨修复和组织工程的原理，在微球材料表面黏附足够的成骨细胞后，植入体内进行骨修复，是骨修复方法中的新思路。选择壳聚糖/β-TCP复合微球以及β-TCP微球作为材料体系。首先采用反相乳液悬浮法制备壳聚糖/β-TCP复合微球，再经过脱脂-烧结工艺获得仅含有B-TCP的无机微球。粒度分析发现，获得的微球球径主要分布在150-450μm范围内，平均球径约300μm。XRD结果显示烧结后的微球中仅有β-TCP相.SEM观察和压汞法测量发现，经烧结后微球表面无尖锐的棱角存在，表面与内部存在大量1．5～5μm的孔隙，孔隙率达到48％以上。复合微球中孔隙较少，其表面较粗糙。细胞培养实验发现细胞在两种微球表面均生长良好，表明它们均具有良好的生物活性和细胞相容性。     

基于显微视觉的微球圆度测量方法研究

利用显微视觉技术结合优化算法对微球的圆度进行自动测量。利用测量显微镜CCD相机采集微球图像,基于最大信息熵原理对图像增强,通过梯度非极大值抑制迭代算法分割图像,提取微球轮廓后进行最小二乘圆拟合,获得微球的圆度参数。该方法避免因滤波后微球目标边缘信息的丢失造成的检测精度降低。通过对0.5mm微球圆度测量实验证明:微球目标轮廓检测与提取的方法可以有效地抑制噪声干扰的影响,高效率实现目标边缘的准确定位;采用该方法获得的微球圆度值与标定微球圆度值之间的相对误差在0.17%之内,能够达到对微球圆度有效检测的目的。     

靶丸材料及氘氚冰层分布对冷冻靶温度场的影响

冷冻靶靶丸氘氚(DT)内冰层均匀性直接影响到惯性约束聚变(ICF)点火成功率,衡量冰层均匀性的重要指标为靶丸表面温度均匀性。本文利用CFD软件对球腔内的温度场与速度场变化进行模拟,包括恒定冷臂温度下的稳态工况和非稳态降温过程,研究了不同烧蚀层材料以及冰层形貌下的冷冻靶丸传热特性和温度场分布。结果表明,高导热性烧蚀层材料对于提高冷冻靶温度场均匀性具有积极作用,当材料的导热系数高于400 W/(m·K)时,该球形冷冻靶靶丸外表面温差已小于0.01 mK。在非稳态降温过程中,比热容和导热系数大的高密度碳(HDC)材料的靶丸外壁面温差比碳氢聚合物靶(CH)靶丸约减少81%。     

ICF靶丸表面形貌及球度误差检测

为了对ICF靶丸的表面形貌及球度误差进行高精度测量,开发了一台五轴坐标测量机,并采用锥光全息技术的激光测头实现对靶丸表面的高精度、非接触检测。首先,根据靶丸表面的结构特点,改进了基于最小二乘的球度误差评价算法;然后,介绍了作为实验平台的五轴坐标测量机的整体配置,推导了该坐标测量机的测量数学模型,该坐标测量机可实现在多个姿态下对靶丸的非接触取点测量;最后,在相同条件下,进行了5次实验测量,其结果表明:靶丸球度误差测量的均值为0.0021 mm,标准差为2.07 x10^-4 mm。该检测方法可以满足对靶丸表面形貌及球度误差高精度、高稳定性的测量要求。     

聚脲微球表面粗糙度及水性涂层消光性调控

以异佛尔酮二异氰酸酯（IPDI）为聚合单体,2,4-二胺基苯磺酸钠（MPDSA-Na）为亲水单体,SiO₂作为表面粗糙剂,通过沉淀聚合法在水/乙腈体系中制备了不同粒径和表面粗糙度的聚脲微球。将其用作水性聚氨酯涂层消光助剂,通过调节MPDSA-Na用量、IPDI用量和SiO₂用量等来控制微球的粒径和表面粗糙度,进而调节涂层的光泽度。结果表明:增加MPDSA-Na用量可减小微球的粒径并提高其在水中的分散稳定性,而提高溶剂中乙腈的比例和增加IPDI用量可增大微球的粒径;作为表面粗糙剂,提高SiO₂用量使微球粒径和表面粗糙度增大,在反应体系开始浑浊时加入SiO₂,微球表面粗糙度最大;粒径介于1～2μm、表面粗糙度高的聚脲微球具有更好的消光效果,所制备水性聚氨酯涂层的光泽可调控至1.6°以下（60°入射角）。     

数字全息在粗糙度检测中的应用

提出一种用数字全息测量物件表面粗糙度的新方法,基于离轴无透镜数字全息理论推导获得了表面粗糙度Ra值和用数字全息法获得的相位解包裹后相位分布之间的关系式,发现用此方法不需要用数字全息获得的真实的相位分布,而用相位解包裹后的相对相位分布即可.实验结果表明用此方法测量物件表面粗糙度是可行的并且变动度较小.     

表面粗糙度三维测量和评定的研究

本文论述了应用相移干涉原理测量三维表面粗糙度,给出了测量系统的组成,实现相移的微位移器件压电陶瓷应用,三维表面粗糙度评定参数的确定。     

弹性磨具磨削M330钢材实验研究

为提高球头弹性磨具磨削M330钢材的加工效率和磨削效果,采用#600球头磨具进行磨削M330钢材实验.通过设计正交实验,研究了不同磨削参数时M330试样的表面形貌和材料去除机理,并得到了初步优化参数.通过单因素实验进一步优化了工艺参数.实验结果表明:增大球头磨具直径、供液速度及减小进给速度,均能降低表面粗糙度;磨削后试样表面粗糙度随设定磨削深度的增加先减小后增加;采用的高速供液法能显著降低试样表面粗糙度,有效改善球头磨具表面的切屑黏附现象;采用高速供液后,可在保证磨削质量的前提下提高进给速度;主轴转速越高,对应最佳供液速度越高.实验得出的不同主轴转速下对应的最佳供液速度为使用MOORE-450CPW连续轨迹坐标磨床进行的磨削加工提供了参照依据.     

粗糙表面可见光散射特性的实验研究

为了获得目标材料表面的散射参数,设计了一种测量粗糙表面散射特性的实验装置,并对几种材料进行了测量.激光器发出的激光经样品反射散射后,被探测器接收,转动转台,完成在入射平面的测量.利用Matlab对实验数据曲线拟合,给出了材料表面散射特性的数学表达式.实验结果表明,散射特性与表面粗糙度和入射角相关.当以中大角度照射时,粗糙表面不再严格遵守朗伯余弦定律,出现非镜向峰值现象,且峰值随着入射角的增大而增大.     

Examination of surface roughness on light scattering by long ice columns by use of a two-dimensional finite-difference time-domain algorithm

Natural particles such as ice crystals in cirrus clouds generally are not pristine but have additional microroughness on their surfaces. A two-dimensional finite-difference time-domain (FDTD) program with a perfectly matched layer absorbing boundary condition is developed to calculate the effect of surface roughness on light scattering by long ice columns. When we use a spatial cell size of 1/120 incident wavelength for ice circular cylinders with size parameters of 6 and 24 at wavelengths of 0.55 and 10.8 microm, respectively, the errors in the FDTD results in the extinction, scattering, and absorption efficiencies are smaller than approximately 0.5%. The errors in the FDTD results in the asymmetry factor are smaller than approximately 0.05%. The errors in the FDTD results in the phase-matrix elements are smaller than approximately 5%. By adding a pseudorandom change as great as 10% of the radius of a cylinder, we calculate the scattering properties of randomly oriented rough-surfaced ice columns. We conclude that, although the effect of small surface roughness on light scattering is negligible, the scattering phase-matrix elements change significantly for particles with large surface roughness. The roughness on the particle surface can make the conventional phase function smooth. The most significant effect of the surface roughness is the decay of polarization of the scattered light.     

表面粗糙度对喷丸残余应力场的影响

为定性研究表面粗糙度对喷丸残余应力场的影响,采用余弦曲线模拟靶材粗糙表面,建立喷丸二维有限元模型,采用ABAQUS/EXPLICIT求解器对喷丸过程进行数值模拟,研究了表面粗糙度喷丸残余应力场的影响规律,分析了同一粗糙度下弹丸尺寸和喷射速度对喷丸残余应力场的影响规律,并与表面理想光滑时的情况进行了对比.结果表明,表面粗糙度的增加使残余压应力区变浅变薄,甚至使靶材表面产生残余拉应力,不利于喷丸强化件抗疲劳性能的提高,喷丸件表面应尽可能光滑以改善喷丸效果.     

Measurements of radar wave speeds in polar glaciers using a down-hole radar target technique

A new technique for measuring the speed of radar waves in polar ice sheets was developed to investigate a previously reported disagreement between the permittivities of laboratory and glacier ice. The technique involves lowering a cylindrical radar target to several carefully measured depths in a borehole and measuring the travel time of a radar wave transmitted from a surface radar unit to the target in the borehole. The experiment was performed at Dome C, East Antarctica, and Dye-3, Greenland, and useable data were collected for target depths between 200 and 800 m. After computing the range to the target along a straight ray path and after correcting the travel time for delays in the radar receiver, the velocities determined from these experiments were found to be in good agreement with the velocities predicted by Robin's empirical formula. The apparent discrepancy between the permittivity of glacier ice, as measured using the radar wide-angle reflection method, and laboratory ice now seems to be due in large part to signal delay in the radar receiver that was ignored in earlier experiments.     

复杂非球面镜高效超精密车削加工法(英文)

本文中对复杂面形的非球面镜进行了分类,并从加工方法和加工路径优化设计等方面研究了复杂非球面镜的超精密车削方法.对回转对称的复杂非球面镜进行了加工实验,并借助超精密测量技术对各段曲面进行面形测量,依据测量结果实现面形补偿加工.最终粗糙度Ra达5.14 nm,形状精度P-V值达200 nm.采用提出的方法对非回转对称的非球面阵列进行加工路径设计,根据具体面形进行加工参数选择和实际加工,得到粗糙度Ra为7.81nm的表面.实验结果证明了提出的加工方法高效实用,可以满足大部分复杂非球面的应用需求.     

Thermophysical Properties of Liquid AlTi-Based Alloys

The surface tension and density of three liquid AlTi-based alloys (AlTiV, AlTiNb, and AlTiTa) have been measured using electromagnetic levitation as a tool for containerless processing. Surface tension has been determined by the oscillating-drop method, while the density was measured using a shadowgraph technique. Both quantities were determined over a wide temperature range, including the undercooled regime. In addition, sessile-drop and pendant-drop experiments to determine the surface tension were performed in a recently built high-temperature furnace. The measured data were compared to thermodynamic calculations using phenomenological models and the Butler equation. Generally, good agreement was found.     

Optimisation of cutting parameters for minimizing carbon emission and maximising cutting quality in turning process

Modern manufacturing systems are faced with the challenge of reducing the carbon emission related to manufacturing technologies. Machining centres consume large amounts of energy and as a consequence; carbon emissions are generated owing to this consumption. This paper presents a design of experiment work related to the optimisation of machining factors in the turning process of aluminium alloys. Carbon emission and surface quality were concurrently optimised. A set of experimental scenarios was set using a Box–Behnken design and the response surface methodology was applied to get the regression model for the carbon emission and surface roughness during turning process. The relationship between factors and the responses (carbon emission and surface quality) was investigated using surface plots. Furthermore, the desirability function method using the Response Optimizer tool in MINITAB and goal programming methodology was used to obtain the values of the parameters that achieved minimum surface roughness and a minimum quantity of carbon emission.     

Determination of Optimal Parameters for SKD11 CNC Turning Process

This study investigated the optimization of a CNC turning process for SKD11 (JIS). The design of experiments (DOE) method with an orthogonal array was applied. Nine experimental runs were performed based on the orthogonal array. The surface properties of roughness average and roughness maximum and the roundness were studied; the analysis of variance (ANOVA) was adapted to investigate which parameters had the most influence on the CNC turning process for SKD11 (JIS). Also, models for predictions of the roughness average, roughness maximum, and roundness had been developed in terms of cutting speed, feed rate, depth of cut, and the mixture ratio of cutting fluids.     

Visualization of 3He Nucleate Boiling Below 1 K

Boiling behavior of liquid ³ He below 1 K was visualized as shadowgraph image. A light source and a video camera (or still camera) were arranged at room temperature. The light was guided to the ³ He cell by an optical fiber, and the shadowgraph image was transferred to the camera by an image fiber. The ³ He bubble formed on the heated copper surface was spheroid-like due to the low surface tension. The size at departure from the surface and the relative bubble formation rate were measured as a function of heat flux. The previously obtained heat transfer curve could be explained qualitatively by this boiling behavior.     

Comparison of the Consequences of Shot Peening Treatment Methods on the Surface Layer Characteristics of Ti6246

Shot peening, as a technique to enhance the surface characteristics of rotating parts in aircraft engines is well known as a way to prevent the initiation and propagation of cracks. However, shot peening generally increases the surface roughness and therefore, reduces aerodynamic efficiency on aerofoil. This paper aims to compare different shot peening procedures as regards roughness, hardness, residual stress magnitude and depth in Ti6246, in order to identify a method, which leads to the required mechanical properties, but keeps the increase of surface roughness to a minimum. Therefore, Ti6246 specimens, processed similarly to integral bladed compressor disks, are treated with defined target intensity and coverage. The changes in surface roughness, residual stress, and hardness are measured and discussed.