Bubble collapse in solid-liquid two-phase fluid

Equations of motion for bubble collapse in solid-liquid two-phase fluid have been derived, in which the resistance coupling effects between the liquid and solid particles have been considered. The motion of particles during the bubble collapse and the effects of particles on bubble collapse have been calculated and discussed. Qualitative relations between the concentration and the size of the particles and the rate of bubble collapse have been obtained. Institute of Water Conservancy and Hydroelectric Power Research     

Real Sample Consistency Regularization for GANs

Mode collapse has always been a fundamental problem in generative adversarial networks. The recently proposed Zero Gradient Penalty (0GP) regularization can alleviate the mode collapse, but it will exacerbate a discriminator’s misjudgment problem, that is the discriminator judges that some generated samples are more real than real samples. In actual training, the discriminator will direct the generated samples to point to samples with higher discriminator outputs. The serious misjudgment problem of the discriminator will cause the generator to generate unnatural images and reduce the quality of the generation. This paper proposes Real Sample Consistency (RSC) regularization. In the training process, we randomly divided the samples into two parts and minimized the loss of the discriminator’s outputs corresponding to these two parts, forcing the discriminator to output the same value for all real samples. We analyzed the effectiveness of our method. The experimental results showed that our method can alleviate the discriminator’s misjudgment and perform better with a more stable training process than 0GP regularization. Our real sample consistency regularization improved the FID score for the conditional generation of Fake-As-Real GAN (FARGAN) from 14.28 to 9.8 on CIFAR-10. Our RSC regularization improved the FID score from 23.42 to 17.14 on CIFAR-100 and from 53.79 to 46.92 on ImageNet2012. Our RSC regularization improved the average distance between the generated and real samples from 0.028 to 0.025 on synthetic data. The loss of the generator and discriminator in standard GAN with our regularization was close to the theoretical loss and kept stable during the training process.     

冲击载荷下孔隙塌缩过程的数值模拟

爆炸压实过程中多孔体的孔隙闭合程度对压实效果起着决定性作用。利用LS-DYNA有限元程序,对无氧铜中的圆形孔隙塌缩过程进行了数值模拟。根据模拟结果分析得出,在6 GPa的冲击压力下,孔隙闭合时不同边界区域会发生爆炸焊接和射流侵彻,这2种结合机理可以使材料结合更牢固,提高材料的致密度和机械强度,实现高质量的爆炸压实。     

Anisotropic collapse in three-dimensional dipolar Bose-Einstein condensates

We study the (3+1)-dimensional Gross-Pitaevskii / Nonlinear Schrödinger equation describing a dipolar Bose-Einstein condensate. Bound states are computed using accurate numerical techniques. When the dipolar strength is negative, the total number of atoms vs. frequency relationship for these bound states is multi-valued and possesses a cusp point, which corresponds to a “candlestick” ground state. Direct simulations of this ground state exhibit strongly-anisotropic collapse of its nucleus, with different contraction rates along the dipole axis and perpendicular to it. We propose an anisotropic self-similar theory to explain this dynamics. The physical implications are discussed.     

基于质心Voronoi图重构的UDSM边折叠简化

城市数字表面模型网格(UDSM)的相邻网格常常出现曲率剧变,而这些位置是UDSM的细节部分,简化过程中应当尽量保持。针对该情况,引入了质心Voronoi图重划分网格,将曲率较小的表面的点云密度大大降低。重划分的网格表面细节与周围的平滑表面的三角网格尺寸悬殊,在该基础上使用二次误差矩阵边折叠进行LOD构建时网格发生明显变化,范围大大减少。算法在时间性能与网格误差与直接边折叠相近的前提下,更多地保存简化后的网格细节。     

氮掺杂对氢终端金刚石射频器件特性的影响

采用微波等离子体化学气相沉积(MPCVD)技术,通过改变气源中的氮含量,得到不同结晶质量的单晶金刚石,通过激光切割以及抛光控制样品尺寸为5 mm×5 mm×0.5 mm,然后对样品进行表面氢化处理并研制了金刚石射频器件,系统研究了氮含量对金刚石材料晶体质量和金刚石射频器件性能的影响。随着氮含量的增加,虽然单晶金刚石生长速率有所增加,但是其拉曼半峰全宽(FWHM)、XRD摇摆曲线半峰全宽也逐渐增加,光致发光光谱中对应的NV缺陷逐渐增多,晶体结晶质量逐渐变差,不仅导致沟道载流子的迁移率出现退化,而且也使金刚石射频器件出现了严重的电流崩塌和性能退化问题。通过降低氮浓度,提升材料的结晶质量,沟道载流子迁移率得到显著提升,金刚石射频器件的电流崩塌得到有效抑制,电流增益截止频率f_T和功率增益截止频率f_max分别从17 GHz和22 GHz大幅度提升至32 GHz和53 GHz。     

Collapse of Entangled State and Entropy Increase in an Isolated System

We show that the collapse of the entangled quantum state makes the entropy increase in an isolated system. The second law of thermodynamics is thus proven in its most genera/form.     

钟摆状态下湿颗粒坍塌流动行为及其动力相似性

基于建立的湿颗粒离散动力学模型,本文系统研究了钟摆状态下湿颗粒柱在重力驱动下的坍塌流动过程,主要考虑了颗粒粒径、液体表面张力系数和液体含量等参数对系统坍塌流动模式和动力学行为的影响。研究发现,在湿颗粒系统中,颗粒粒径和液体表面张力系数会改变颗粒间的毛细力大小,引起系统发生不同的坍塌流动模式,而液体含量仅定量影响颗粒坍塌后的堆积形态。在此基础上,进一步探讨了不同模式下系统坍塌流动行为与模型参数的相关性,发现无量纲Bond数是决定钟摆状态下湿颗粒物质坍塌流动动力学行为的本质因素。     

水下爆炸气泡射流载荷计算的新方法研究

由于存在强冲击、多相界面复杂运动等强非线性效应,目前对于水下爆炸气泡运动的计算方法无法给出较为可信的水射流运动特征及其载荷形式.本文基于多相可压缩流体的five-equation计算模型,引入界面函数和界面密度压缩技术,采用5阶WENO重构与HLLC近似Riemann求解器进行空间离散,时间离散采用3阶TVD Rung...     

正弯矩和拉力共同作用下刚性组合节点承载力计算方法

框架结构中某柱发生失效会造成梁跨度增加,进而导致梁的内力增大、跨中挠度变大,作用在失效柱上方节点的荷载组合也由负弯矩转变为同时存在的拉力和正弯矩．针对此工况,本文对在正弯矩和拉力作用下的刚性钢-混凝土组合节点进行内力分析,采用内力平衡法推导了拉弯承载力公式,并与相应的组合梁及钢梁的公式进行对比．同时利用ABAQUS有限元软件建立组合节点的有限元分析模型,得到不同参数下钢-混凝土组合节点的拉弯相关曲线,并与本文所提出的公式的计算结果进行了对比,两者吻合较好,为刚性组合节点在拉力和正弯矩共同作用下的拉弯受力设计提供了一定的参考依据．