Numerical simulation of two-phase flow field in underwater sealing device based on dynamic mesh

In order to speed underwater launch of minor-caliber weapons,a sealing device can be set in front of underwater muzzle to separate water,preventing the muzzle from water immersion.By establishing and simplifying the model of underwater weapon sealing device and unstructured mesh computing domain model based on computational fluid dynamics（CFD）,dynamic mesh and user defined function（UDF）,the N-S equation is solved and the numerical analysis and calculation of the complex two-phase flow inside the sealing device are carried out.The results show that the gas discharged from the sealing device is conducive to the formation of the projectile supercavity.When the projectile is launched at 5munder water,the shock wave before and after the projectile has impact on the box body up to 100 MPa,therefore the sealing device must be strong enough.The research results have the vital significance to the design of underwater weapon sealing device and the formation of the projectile supercavitation.

开谱大典与演戏习俗杂谈

宗谱,作为汉民族独特的一种文化现象,已经绵延千百载了,其间所包涵的民俗民风民族心态,厚重的历史内蕴以及在学术上的价值,颇值得进行探讨与研究。而在赣东北的乐平、鄱阳一带,宗谱的续修之风尤盛,其组织之严谨,过程之繁复,形式之讲究,仪式之隆重,堪称乡村文化活动之最。本文仅就宗谱修成后的开谱大典仪式及演戏习俗作一陈述,即就修宗谱与戏曲演出的有关内容做一些说明,作为抛砖引玉。

Ex⁃situ Measurement of Internal Deformation in Ball Grid Array Package with Digital Volume Correlation

In spacecraft electronic devices,the deformation of solder balls within ball grid array(BGA)packages poses a significant risk of system failure.Therefore,accurately measuring the mechanical behavior of solder balls is crucial for ensuring the safety and reliability of spacecraft.Although finite element simulations have been extensively used to study solder ball deformation,there is a significant lack of experimental validation,particularly under thermal cycling conditions.This is due to the challenges in accurately measuring the internal deformations of solder balls and eliminating the rigid body displacement introduced during ex-situ thermal cycling tests.In this work,an ex-situ three-dimensional deformation measurement method using X-ray computed tomography(CT)and digital volume correlation(DVC)is proposed to overcome these obstacles.By incorporating the layer-wise reliability-guided displacement tracking(LW-RGDT)DVC with a singular value decomposition(SVD)method,this method enables accurate assessment of solder ball mechanical behavior in BGA packages without the influence of rigid body displacement.Experimental results reveal that BGA structures exhibit progressive convex deformation with increased thermal cycling,particularly in peripheral solder balls.This method provides a reliable and effective tool for assessing internal deformations in electronic packages under ex-situ conditions,which is crucial for their design optimization and lifespan predictions.

留住传统脚步 重现例戏风采——佛山、香港相继整理演出《香花山大贺寿》

近年来,粤剧界开始注重重新发掘整理并排演例戏。自2010年香港八和会馆以《玉皇登殿》作为香港代表节目参与上海世博会始,及广东粤剧院重排了《六国大封相》《玉皇登殿》获得赞誉后,2017年粤港粤剧界更掀起了一阵重排例戏的热潮。

An Analytical Solution of Melting around a Moving Elliptical Heat Source

This paper studies the close-contact melting around a moving, horizontal elliptical heat source thatmelts its way through a phase change material under its own weight. The heat source velocity andthe volume of the material melted are obtained by analysis. The effects of compression coefficient andtemperature distribution in the melt are investigated. The results include that for melting around amoving cylindrical heat source.

A HPLC method for the determination of entrapment efficiency of a new 5-FPE liposome formulation

A simple HPLC method was established for the determination of entrapment efficiency of a new 5-FPE liposome formulation. Chromatographic separation was performed on a Kromasil 100 A C18 column （350 mm×4.6 mm, 5 μm）. The mobile phase was consisted of methanol-water （58：42, v/v）. The flow rate of mobile phase was set at 0.8 mL/min. The UV detection wavelength was 271 nm, and the column temperature was 30 ℃. The linear range of 5-FPE was from 0.8-12.8 μg/mL, r = 0.9999. The RSD of intm-day and inter-day precision were less than 2.97%. The average recovery was from 96.8%-104.6% with RSD less than 2.24%. The method was simple, rapid, accurate, and sensitive. It is suitable for the determination of entrapment efficiency of the 5-FPE liposome formulation.

Encapsulation of RNA by negatively charged human serum albumin via physical interactions

Human serum albumin(HSA)is the most abundant plasma protein and has an inherent ability to target tumor cells.It is an excellent candidate for drug delivery.However,HSA cannot form complex with DNA or RNA,because it is negatively charged under physiological conditions.In this work,we reported a simple method to prepare HSA/RNA nanoparticles mainly by physical interaction.Firstly,the solution p H is adjusted to 4.0,under which condition HSA is positively charged.It forms complex with RNA via electrostatic interaction.The solution is then heated at 75 oC for 15 min to stabilize the structure and the size of the formed complex.The HSA/RNA nanoparticle prepared by this method has a diameter about 110 nm and a narrow distribution.It is also stable for days under physiological conditions.Cellular essays demonstrate that these particles exhibit a high cellular uptake efficiency and non-toxicity to He La cells.

Improved biocompatibility of phosphorylcholine end-capped poly(butylene succinate)

In this work, the biocompatibility of a biomimetic, fully biodegradable ionomer phosphorylcholine (PC)-functionalized poly(butylene succinate) (PBS-PC) was investigated by means of hemolysis, platelet adhesion, protein adsorption and cytotox- icity experiments. The reference materials were poly(butylene succinate) (PBS) and chloroethylphosphoryl functionalized poly(butylene succinate) (PBS-Cl). The hemolysis rates (HR) of the leaching solutions of PBS, PBS-Cl and PBS-PC were all lower than the safe value, and the rate of PBS-PC was reduced to 1.07%. Scanning electron microscopy (SEM) measurements showed that platelet adhesion and aggregation were significant on both PBS and PBS-Cl surface. In contrast, very few platelets were observed on PBS-PC surface. Bicinchoninic acid (BCA) measurements revealed that the adsorption amounts of bovine serum albumin (BSA) and bovine plasma fibrinogen (BPF) on PBS-PC surface were 52% and 72% reduction respectively compared with those on PBS surface. Moreover, non-cytotoxicity of both PBS-PC particles and its leaching solution was sug- gested by MTT assay using mouse L929 fibroblast cells. All the results demonstrated that the biocompatibility of PBS could be greatly improved by PC end-capping strategy. This PC functionalized polyester may have potential applications in biological environments as a novel carrier for controlled drug release and scaffold for tissue engineering.

Accurate mirror-based camera pose estimation with explicit geometric meanings

An accurate closed form solution is proposed to estimate camera pose by several mirrored reference object images acquired via a planar mirror under different unknown poses. Compared with state-of-the-art methods, our method is more accurate when there are more than three images and has explicit geometric meanings. This method also properly handles cases in which some of the mirror poses are parallel. The central idea is to minimize an error metric based on all reflections of rotation, which enables the camera rotation to be estimated directly by SVD of sum of mirrored camera rotations. After that, the camera translation is computed by solving a large system of linear equations to minimize object space collinearity error. Both synthesized data and real data experiments show the advantages of our approach.

Fluid-solid strong-interaction model of mechanical seals in reactor coolant pumps

The studies on the mechanisms and performances of the mechanical seals in reactor coolant pumps are very important for the safe operations of the pressurized water reactor power plants. Based on the hydrostatic mechanical seal in reactor coolant pumps, an analytical fluid-solid strong-interaction model is proposed in this paper. According to the design features and operafional principles of the seal, an analytical method to calculate the mechanical deformation of the seal assembly is developed based on the ring deformation theory. A strong-interaction algorithm combining the analysis of the mechanical deformation of the seal assembly and flow field between the seal faceplates is utilized, in which the three kinds of equations including the fluid domain, solid domain and coupling action are constituted in the same equations set and all the variables are solved simul- taneously. So the analytical fluid-solid strong-interaction model used for the seal is built. Moreover, the model is verified by the experimental results. Based on the model, the design parameters of the seal are studied. Two different conditions of the general case and fixed seal leakage rate are discussed respectively, and the regularities that the seal behaviors are affected by the parameters of the holding screws on the clamp rings and seal faceplates are obtained. The research results can provide a theoretical basis for performance analysis, design and assemblage of the seal. Compared to the numerical methods, the proposed model has the unique advantages of high efficiency, convenience and easy application of constraints.