Unsteady interfacial phenomena during inward weld pool flow with an active surface oxide

Abstract

Particle image velocimetry (PIV) was applied to estimate the velocity field on a weld pool surface with an oxide layer. A positive surface tension gradient drives an inward flow pattern from the boundary to centre of the weld pool, resulting in particles collecting on the centre line of the pool at the surface. Unsteady flow motions were observed by experimental visualisation of the particle flow, and the computed velocity field shows strong unsteady interfacial movement during inward flow. These unsteady flow motions are related to clockwise and counterclockwise vortices on the weld pool surface, which in turn affect both mass flow and energy transport. Both the qualitative flow motion and quantitative flow velocity are described in this work, which contributes to explaining the characteristic unsteady fluid flow in the weld pool, the measurements also provide experimental data for validation of numerical fluid flow models of the weld pool.     

Numerical modelling for rotational moulding with non-isothermal heating

Abstract

In the rotational moulding process, the internal air temperature has been widely recognised as a tool to predict an optimum cycle time. This paper presents a new numerical approach to predict the internal air temperature in a two-dimensional (2-D) static model without requiring the consideration of the tumbling motion of polymer powder. The initial non-isothermal heating of the static model is actually formed by two changeable plastic beds (stagnant and mixing beds), which represent the actual stagnant and mixing pools inside a rotating mould respectively. In the numerical approach, the lumped-parameter system and coincident node technique are proposed to incorporate with the Galerkin Finite Element Method in order to account for the complex thermal interaction of the internal air. It helps to overcome the difficulty of multidimensional static models in predicting an accurate internal air temperature during the heating stage of rotationally powdery plastic. Importantly, the predicted temperature profiles of the internal air, oven times for different part thicknesses and process conditions accord with the available experimental results.     

核心网分布式HSS/HLR引入FE POOL组网方案研究

通过对FE动态用户接入能力、容灾、设备冗余度等多维度对比分析,得出FE POOL组网引入的必要性。其次,分别就负责2/3G用户处理的HLR-FE和负责LTE用户处理的HSS-FE组POOL方案原理给出详细描述,并就部署FE POOL的相关要求、需考虑的问题以及运营商未来引入FE POOL组网的策略给出初步建议。     

CSFB部署后的网络容灾功能分析

CSFB是LTE重要的语音过渡方案,文章介绍了CSFB技术的组网原理,指出了CSFB部署初期SGs接口对接方案在容灾能力上的缺陷,着重从SGs接口链路、MME和MSC Server三个层面分析了网络的容灾功能,为CSFB建设和维护提供参考。     

Seam tracking based on estimation of weld position using Kalman filtering

Abstract

A seam tracking method is presented based on the estimation of weld position during the gas tungsten arc welding process. Kalman filtering of the weld pool images from a visual sensor is applied to compute recursively the solution to the weld position equations which are established based on an estimation of the centroid position of the weld pool images. This centroid, the position of which corresponds with the weld position, is extracted as the measurement eigenvector. The evolution of the weld position data from the weld pool images can be described through an appropriate process model, so that the weld position can be detected by applying a Kalman filter. This allows adjustment of the welding torch position in real time, which may significantly reduce processing time and promote seam tracking accuracy. Simulations and actual welding experiments have demonstrated the effectiveness of the proposed algorithm in the presence of weld pool image noise and have demonstrated the robustness of weld position detection for seam tracking.     

Spent fuel transport using cask loaded outside pool

Abstract

During the last year, Sogin (the Italian company in charge for decommissioning of Italian nuclear power plants) had to implement an accelerated decommissioning plan of a EUREX spent fuel pool due to finding a water leakage into the environment from the pool. EUREX is no longer operating a pilot reprocessing plant, which some years ago became the responsibility of Sogin. There were 52 spent fuel assemblies from the Trino Vercellese PWR nuclear power plant, 48 irradiated pins from a Garigliano BWR fuel assembly, and 10 plates from an irradiated MTR fuel assembly stored in the EUREX pool, so the first step of the accelerated decommissioning plan consisted in the evacuation of this spent fuel. Considering the necessity to start the evacuation as soon as possible, Sogin decided to use an already existing cask (AGN-1) used in the past for the transport of Trino and Garigliano fuel assemblies. This cask was requalified in order to obtain a transport licence for the fuel assemblies stored in the EUREX pool according to ADR 2005 regulation. The transport license for the AGN-1 cask loaded with EUREX fuel assemblies was released by APAT (the Italian Safety Authority) in the spring of 2007. Owing to the limited capacity of the EUREX pool crane (27 t for nuclear loads) and limited dimensions of pool operational area, it was not possible to transfer the AGN-1 cask (50 t) into the pool for fuel assemblies charging. The solution implemented to overcome this problem was the loading of the cask outside the pool. A special shielding shuttle was developed and used to allow safe spent fuel transfer between the pool and the cask. This procedure avoided also the problem of excessive contamination of cask surfaces that could have occurred due to very high level of contamination of EUREX pool water if the cask had been immersed in the pool. Additional shielding devices were developed and used to reduce dose rate during cask loading operations. Although the evacuation of spent fuel assemblies from the EUREX pool was a very challenging activity due to the short time available, unfavourable space conditions inside the pool building and handling tool limitations; all loading and transport operations were performed successfully and without particular problems. Ten transports were carried out to evacuate all of the spent fuel stored in the EUREX pool. Spent fuel was transferred to the Avogadro Deposit pool. The first loading sequence started on 2 May 2007 and the first transport was performed on 6 May 2007. The tenth and last transport was performed on 21 July 2007. A dose less than 50 μSv (neutron + gamma) was measured for the most exposed operator during a complete cask loading sequence.     

VoLTE网络跨Pool容灾方案研究设计与实现

核心网集中化、扁平化的组网特点,在实现资源共享、业务快速部署等优势的同时,机房、电源、承载网、传输网等环节成为核心网多网元同时故障的潜在隐患,网络传统的单板级、网元级、POOL级容灾技术和机制已无法应对其带来的重大影响。本文就是为了解决上述问题,通过多维风险分析和网络能力分析,提出容灾率算法,实现VoLTE网络POOL内资源容灾能力的量化判定,基于该算法构建跨POOL容灾模型,通过四级定损,场景预置、网络资源动态调用,实现VoLTE业务跨POOL网络容灾,强化VoLTE核心网容灾体系化保障能力,实现重大网络故障下的业务快速恢复。     

IMS核心网组网技术研究

IMS（IP Multimedia Subsystem,IP多媒体子系统）最早由3GPP提出,为在移动通信网络上提供多媒体业务,后被业界广泛认同,逐渐扩展为适用于固定宽带、cable等多种接入方式的统一核心控制网络。目前IMS已经成为国际主流标准组织对下一代网络控制架构的共同选择,各运营商都在着手开展IMS网络的试点或商用建设。本文首先对IMS引入驱动力进行了分析,然后重点对IMS双POOL组网技术以及大区制组网技术进行了说明以及优劣势对比。     

Enhanced melt pool stirring in welding with dynamic polarised laser beam

Abstract

The stirring of the molten material during CO₂ laser welding with a dynamic polarised laser beam (DP) was studied. The key element of the set-up is a high power interference laser beam modulator for CW power rating up to 4 kW. Metallographic cross-sections and EDX analyses of the realised welds in St37 using the contrast material nickel proved the enhancement of melt pool stirring due to DP. Moreover, roughness measurements confirmed a smoothing of the top bead surface as well as a correlation between melt pool stirring and the formation of the top bead ripple structure.     

双序列法及其在油气资源评价中的应用

在Pareto定律基础上，提出计算资源量的双序列法，继承了油藏规模序列法的使用简便、易于实现等优点，消除了其缺陷：①引入误差分析系统，使关键参数的调试更快捷、更准确；②采用双序列模型，大大拓宽了应用范围；③纳入资源分布体系，能更科学地表示资源量计算结果。通过在黄骅坳陷南皮凹陷kd区带的评价实例，展示了这种方法的应用过程、评价思路。评价结果得到有关专家的认可，表明双序列法是一种科学、有效的油气资源评价方法.图2表2参9