深亚微米光记录测试仪

详细描述了进行亚微米、深亚微米光记录和探测的测试仪器，其探测功率可达30mW，最小的探测时间为20ns，探测的最小光点200nm左右，带有CCD观察的系统可方便地定位及进行图像处理，整个测量过程均在计算机控制下进行，操作非常方便，它是对高密度光盘材料记录性能进行测量，以及对深亚微米，乃至纳米记录材料进行研究的有效工具。     

K418B合金细晶铸造整体涡轮真空热处理工艺研究

通过力学性能评估和金相组织观察，研究五种热处理制度，两个周期的试验结果，确定了Ｋ４１８Ｂ合金细晶铸造整体涡轮的真空热处理工艺。     

无线传感器网络中d-Hop 2-连通容错支配集的分布式构造算法

无线传感器网络随节点移动组成自我维持的自组织系统,采用连通支配集的虚拟骨干技术可使平面网络系统层次化而简化节点路由、管理和维护。但大规模无线传感器网络的连通支配集节点数目依然庞大,d-hop连通支配集可以大大减小支配集节点数目。另外,由于存在节点失效、链路断裂等无线特性,虚拟骨干网需要具备一定的容错性。在单位圆盘图网络模型中为构建精简且具有容错能力的虚拟骨干网,提出d-hop 2-连通支配集的分布式构造算法,先构造d-hop独立支配集后再连通形成d-hop 2-连通支配集。并从理论和仿真上对算法的复杂度、近似比和算法性能作了进一步探讨和验证。     

故障硬盘的数据备份与销毁

硬盘承载着重要数据,它的精密度很高,而且它内部的机械运动快速而准确。一旦这个精密装置的某一部分出现了故障,存储在里面的数据就无法访问,甚至有可能会永久丢失。修复硬盘,找回数据,是数据恢复工程师的神圣使命。一般来说,经修复的硬盘稳定性已大为下降,所以不建议继续使用。但硬盘不用后也不能随意丢弃,因为里面还存储有机密数据,应当将其数据销毁。本文就针对带有坏扇区故障硬盘的数据如何实现数据备份与销毁,以便用户能读出(或销毁)其中重要的数据。     

多虚拟机环境下磁盘写优化机制

在虚拟化环境下,如何在写直达法和写回法之间做出权衡以使系统既具有较好的可靠性又具有较高的磁盘读写性能,是一个亟待解决的问题。本文提出了基于XEN的兼有写直达法和写回法优点的磁盘数据写操作方法。通过修改虚拟机块设备前后端驱动程序,在虚拟机管理器中为每个虚拟机建立块级别的虚拟机磁盘缓存。虚拟机中的应用程序均采取写直达的方式,将数据直接写到位于虚拟机管理器的虚拟机磁盘缓存中。结果表明,该机制能为虚拟机提供高效率的磁盘读写操作,同时,在虚拟机系统突然宕机时也能保证用户数据的完整性和可靠性。     

计算机硬盘坏磁道修复的思路与技巧

本文通过隐藏坏磁道分区的方法,着重介绍了硬盘坏磁道的修复技术及注意事项,同时还介绍了逻辑坏磁道、0磁道损坏的修复方法。     

The statistical modeling of surface roughness in high-speed flat end milling

Surface roughness is one of the most important requirements in machining process. The surface roughness value is a result of the tool wear. When tool wear increase, the surface roughness also increases. The determination of the sufficient cutting parameters is a very important process obtained by means of both minimum surface roughness values and long tool life. The statistical models were developed to predict the surface roughness.This paper presents the development of a statistical model for surface roughness estimation in a high-speed flat end milling process under wet cutting conditions, using machining variables such as spindle speed, feed rate, depth of cut, and step over. First- and second-order models were developed using experimental results of a rotatable central composite design, and assessed by means of various statistical tests. The highest coefficient of correlation (R_adj²) (88%) was obtained with a 10-parameter second-order model. Meanwhile, a time trend was observed in residual values between model predictions and experimental data, reflecting the probable effect of the tool wear on surface roughness. Thus, in order to enhance the estimation capability of the model, another independent variable was included into the model to account for the effect of the tool wear, and the total operating time of the tool was selected as the most suitable variable for this purpose. By inserting this new variable as a linear term into the model, R_adj² was increased to 94% and a good fit was observed between the model predictions and supplementary experimental data.In this study, it was observed that, the order of significance of the main variables is as X₅>X₃>X₄>X₁>X₂ (total machining time, depth of cut, step over, spindle speed and feed rate, respectively).     

Novel methods for rapid assessment of tool performance in milling

The paper examines the effectiveness of two innovative techniques designed to rapidly optimize a milling application. One of them relates to quantifying the relative wear of different insert grades concurrently in a single cutting test, by mounting the inserts in the same cutter, for a quick comparative performance evaluation. Experimental results that illustrate the validity and limitation of this concept, and a scheme for enhancing the reliability of the test method are presented. The other technique refers to rapid identification of the optimum feed/tooth that corresponds to maximum tool life. This entails a test wherein individual inserts in the cutter are subject to feed/tooth that are multiples of a base value, by selectively leaving appropriate number of consecutive insert pockets unoccupied. These novel techniques complement known accelerated tool life tests, and are expedient for industries that engage short production runs, in terms of selecting a suitable insert grade for an application, and determining optimal cutting conditions for the selected grade.     

精确定位的高带宽新型音圈电机驱动器研究

为了在极高磁道密度（TPI）的硬盘中快速寻道定位、读取数据,研发了一种新型高带宽驱动器组件.该新型高带宽驱动器的音圈电机（VCM）具有独特的音圈结构和磁极（体）排列.在电磁设计中,应用三维有限元分析法（FEA）对一些关键电磁参数及主要结构尺寸进行了优化;预测了系统的动态性能.分析表明,新型音圈电机驱动器产生的电磁力形成了纯力矩,降低了轴承和轴上的反作用力,与传统驱动器相比,更好地抑制了影响伺服带宽的横向准刚性体震动模式（QR模式）,使驱动系统能在高TPI下快速跟踪和精确定位.实验测试了系统的频率响应特性,与理论设计符合得较好.