金属凝固微观组织数值模拟研究进展

综述了金属凝固微观组织数值模拟研究在国内外的研究进展，阐述了该研究领域主要采用三种模拟方法（确定性方法，随机性方法，相场方法），并着重介绍了最新的改进单元自动控制法（MCA法）的求解和模拟过程，指出了该研究领域目前存在的问题及今后的发展方向。     

1,4-二(吡啶亚甲基-硫亚甲基)萘的制备及其对Hg~(2+)的识别

以1,4-二氯甲基萘为原料经过反应合成了荧光分子1,4-二(吡啶亚甲基-硫亚甲基)萘,其结构经IR,1H NMR所证实。利用紫外光谱法考察了该化合物对Hg2+的识别性能。结果表明,该化合物对Hg2+具有良好的识别能力。     

07MnNiMoV DR液化石油气储罐用钢焊接工艺及焊后热处理研究

对建造液化石油气低温储罐所用07MnNiMoV DR钢的焊接工艺及焊后热处理等进行了实验研究。结果表明,采用30kJ/cm线能量焊接,焊后经580℃消除应力处理,其焊接接头的力学性能最好,满足散装运输液化气体船舶制造的焊接技术条件要求。     

Polarized spectroscopic properties of Ho-doped LuLiF4 single crystal for 2 μm and 2.9 μm lasers

Polarized spectroscopic properties of a Ho³⁺-doped LuLiF₄ (Ho:LuLF) single crystal grown by the Czochralski method have been investigated as a promising material for 2 μm and 2.9 μm lasers. The Judd-Ofelt (J-O) model has been applied to the analysis of the polarized room temperature absorption spectra to establish the so-called J-O intensity parameters. Based on the calculated parameters, we determined the emission probabilities, branching ratio and radiative lifetime for the Ho³⁺ transitions from the excited state manifolds to the lower-lying manifolds. Ho:LuLF crystal shows long fluorescence lifetime of ⁵I₇ manifold (16 ms) and broad absorption and emission spectra, which exhibit strong polarization characteristics. Stimulated emission cross-sections spectra of the ⁵I₆ → ⁵I₇ and ⁵I₇ → ⁵I₈ transitions were derived and compared with those of the other well-known Ho³⁺-doped laser crystals.     

厌氧胶：可靠且节约成本紧固件的锁紧和密封

当机械设备发生故障时，厌氧螺纹锁固剂便可发挥作用。正如赛车的特滑层有助于确保车辆在赛道的抓地力，螺纹锁固剂有助于保证紧固件螺纹的夹持力。根据厌氧技术，这些金属胶粘剂可以实现机械辅助措施无法实现的功能：它们可完全填满连接螺纹之间的微小间隙。使用螺纹锁固剂固定的螺栓可以提供比机械装置更好的夹紧力。专用螺母或垫圈的价格是液体螺纹锁固剂的5倍以上。采用液体螺纹锁固剂可降低库存成本。在选择螺纹锁固复合物时，有一些关键因素需要考虑：抗剪强度、固化速度、间隙填充能力和工作环境。     

改进蒸脱机上的十字滑块联轴器

摘 十字滑块联轴器的主要失效形式是榫或凹槽面压溃变形，其传递力或力矩的接触面变形后，产生冲击、振动，无法保证联轴器的正常工作，需要整体更换。针对十字滑块联轴器存在的问题，提出了双半联轴器的改进方案。实践证明，经改进的十字滑块联轴器其寿命延长近1倍，而且大大减少了维修工作量。     

光干涉甲烷检测器的光路改进与零点补偿

光干涉甲烷检测器具有稳定可靠性强、测量范围宽等优点,但现有设备都采用人工读数方式,自动化程度低,不能连接到煤矿监控系统。针对该问题,提出了一种基于测量干涉条纹光强的改进方法。通过改进光路设计,保证了甲烷体积分数与光强变化之间对应关系的惟一性。使用光电元件采集干涉条纹,根据干涉条纹的光强变化得到甲烷体积分数。针对光干涉甲烷检测器的零点受外界环境因素影响而发生漂移的问题,首先通过理论分析得到了外界气压与测量误差之间的关系模型,并使用该模型对外界气压变化进行补偿;然后由实验得到温度与测量误差之间的关系,采用线性插值方法建立温度补偿模型。最后通过精度实验、压强实验、温度实验和长期稳定性实验验证了所设计的补偿模型的有效性和系统的稳定性。     

爆炸荷载下露天矿高陡边坡动力响应分析

为研究矿山高陡边坡在爆炸荷载作用下的动力响应规律,采用LS-DYNA软件,对威斯特铜矿的采场边坡进行完全动力有限元计算。对比分析了数值模拟和现场实测环境下爆炸应力波的传播规律,两者结果相接近。同时,通过对各台阶爆破振动速度的统计分析可知,随着台阶高程的增加,在台阶坡顶、台阶边缘至台阶内侧坡脚的1/3至1/2距离处容易产生高程放大效应。另外,利用极限平衡法原理,结合数值模拟计算结果,计算了在炸药起爆后400ms内边坡的时程安全系数,直观描述了爆破动力荷载对边坡稳定性的影响。     

A performance study for IPv4–IPv6 translation in IP multimedia core network subsystem

A Next Generation Network (NGN) is an advanced, packet‐based network that exploits broadband and QoS‐enabled transport technologies for enabling multimedia services. In NGNs, the principles and requirements of IP Multimedia Sub‐system (IMS), which are used to deliver the desired benefits, should be carefully examined and studied. Internet Protocol version 6 (IPv6) is adopted by Third‐generation Partnership Project (3GPP) to solve address storage problem and provide new features (e.g. plug‐and‐play and mobility) for IMS. However, in the early stage of IPv6 deployment, the existing Voice‐over‐IP (VoIP) networks support Internet Protocol version 4 (IPv4) only. For IPv4–IPv6 interworking between IMS and the existing VoIP networks, the IMS‐Application Level Gateway (IMS‐ALG) and the Transition Gateway (TrGW) are proposed to translate Session Initiation Protocol (SIP) and Real‐time Transport Protocol (RTP) packets, respectively. In this paper, we focus on the IPv4–IPv6 translation for RTP packets, which is the bottleneck of VoIP performance. Specifically, we developed a TrGW called National Information and Communications Initiative (NICI)‐TrGW. In NICI‐TrGW, we perform IPv4–IPv6 translation at the Linux kernel and adjust the header room of kernel‐level packet buffer for each packet to reduce memory‐copy operations. We evaluate the performance of NICI‐TrGW and the existing solutions by using the SmartBits. Our study indicates that NICI‐TrGW outperforms the existing solutions in terms of three different output measures including packet loss rate, maximum throughput, and average latency. Copyright © 2009 John Wiley & Sons, Ltd.