变精度下近似算子与程度上近似算子的逻辑与运算模型

基于精度与程度的逻辑与需求,提出了变精度下近似算子与程度上近似算子的逻辑与运算模型。在该模型中,得到了变精度下近似算子与程度上近似算子的逻辑与运算的精确描述与基本性质,提出了宏观算法与微观算法,进行了算法分析与比较,得到了微观算法更具空间优势的结论。最后用医疗实例对模型与算法进行了说明。变精度下近似算子与程度上近似算子的逻辑与运算模型,部分拓展了变精度粗糙集模型、程度粗糙集模型和经典粗糙集模型,并在这些模型中得到了近似算子的相应性质。     

计算机技术与虚拟技术的协同发展

计算机技术的实现与迅速发展,带动了诸多领域的信息技术变革,拓宽了虚拟技术在社会领域的应用。文章从计算机技术与虚拟技术的实践化应用角度出发,简要概述了计算机技术与虚拟技术的相关概念,分析了虚拟技术工作原理,研究了计算机技术与虚拟技术协同发展的特点,并在此基础上探讨了计算机技术与虚拟技术的应用现状与基于虚拟技术的多台计算机协同发展。计算机技术作为一种技术手段,在与虚拟技术有机融合并协同发展的过程中,必将为人们的生产与生活带来了极大的便利。     

统一资源库的研究与实现

在分析了资源与资源库建设的现状后,提出了统一资源库的概念以简化资源的交换、共享与访问,研究了其实现的技术途径,并设计与实现了其原型系统一URMS,验证了统一资源库的可行性与效率。     

基于LonWorks的高校校区智能安防与管理系统的研究

该文简单分析了LonWorks技术的特点,分析了高校校区安防与管理系统的需求与实现,研究了高校校区安防与管理系统.     

网络化仪器成为测量技术与仪器的新发展趋势

随着科学技术的发展,计算机与网络技术得到了广泛的应用,促进了社会经济的发展,实现了其测量技术与仪器的改进,计算机化、网络化的仪器随之产生,促进了其测量的深度与广度。本文将分析网络化测量技术与仪器发展的动力,并介绍网络化仪器及其优势,同时阐述网络化测量技术与仪器的新发展趋势。     

高校智慧教室建设的思考

通过高校智慧化教学环境建设的探索与实践,分析了智慧教室的特征和内涵,阐述了智慧教室特性的构建途径,对智慧教室功能进行了梳理,指出了易用性和可靠性与硬件与软件系统的关系,给出了高校智慧教室建设的相关思考与建议。     

基于S7-200 PLC的垫层多点测厚仪运动控制设计

针对硅泡沫垫层设计了一套多点厚度测试仪,介绍了该装置的技术指标、测量原理与系统构成,着重分析了其中的伺服控制系统的构成与接线,结合本装置所需功能,分析了其运动轨迹与状态,介绍了其速度与精度控制措施,给出了消除伺服传动所带来的测量误差的方法。最后利用S7-200 PLC与上位机虚拟仪器进行串口通信,实现了上位机对伺服系统的监视和控制。     

基于刚体运动与弹性运动的机械系统动力学建模研究

讨论了具有刚体运动与柔性变形的机械系统的动力学建模,将刚体自由度与弹性变形自由度看作广义坐标,利用有限元法对具有刚性运动与弹性变形的机械系统的运动与变形进行了描述,得到了以刚体位移与弹性变形位移表示的单元的广义惯性力;从应力应变入手,得到了表示单元弹性变形与几何非线性变形的结构刚度矩阵与几何非线性刚度矩阵,使用Kane方程推导了弹性连杆机构的单元运动方程,这种建模方法,可以使用在任意结构的机械系统。     

计算机学院学科建设与专业建设的探讨

阐述了高等院校的学科与专业、学科建设与专业建设的内涵及其相互关系,论述了学科建设与专业建设的基本要素,指出了计算机学院在还没有本科专业的情况下提出学科建设的原因及其必要性,探讨了计算机学院的学科建设与专业建设,提出了加强学科建设与专业建设方法和思路。     

网络与信息系统的安全评估与实施

根据目前网络与信息系统的安全状态,分析了网络与信息系统的风险评估技术,提出了风险评估的方法,构造了网络与信息系统的安全体系。     

飞行光学头飞行性能计算机仿真

研究与设计飞行光学头是推出新一代高密度近场光记录光盘驱动器的关键技术之一 .为了灵活方便地对各种结构形式的光学头进行飞行性能分析 ,本文在对飞行光学头进行建模与分析的基础上 ,在 Matlab环境下开发出了飞行光学头飞行性能分析软件 ,给出了飞行光学头的仿真建模及性能分析软件系统的设计思路和总体规划 .     

基于视觉反馈的近场微型飞行头定位系统

近场光存储方案中,头盘间距动态测控技术是将近场光存储理论和技术实用化的一项关键技术。基于强度干涉原理的飞高检测方案中,微型飞行头位姿控制是影响测量误差的一项关键因素。提出一种基于视觉反馈的定位控制系统,重点介绍其系统结构,分析机械控制元件和图像处理算法精度。试验表明,微型飞行头定位系统精度优于11μm,引起飞高检测误差在1nm范围内,满足高精度头盘间距动态测试要求。     

Active flying-height control slider using MEMS thermal actuator

Today’s head/disk interface design has a wide flying height distribution due to manufacturing tolerances, environmental variations, and write-induced thermal protrusion. To reduce the magnetic spacing loss caused by these effects, we developed an active head slider with a nano-thermal actuator. The magnetic spacing of these sliders can be controlled in situ during drive operations. After simulating the heat transfer in the slider to obtain the thermal deformation of the air-bearing surface, we fabricated a thermal actuator using thin-film processing. An evaluation done using a read/write tester showed a linear reduction in the magnetic height as electric power was applied to the actuator. The actuator’s stroke was 2.5 nm per 50 mW with a time constant of 1 ms. There was no significant impact on the reliability of the read element.     

Slit design for the thermal flying height control slider

In this work, we propose a novel thermal flying height control (TFC) slider, by designing a slit near the thermal heater in the slider. Design of the slit can reduce the mechanical constraints on the head elements and concentrate the heat around head elements. In turn, head elements can achieve more thermal protrusion and flying height reduction compared to the traditional TFC slider. The simulation results show that the application of the slit achieves a flying height reduction of 1.4 nm at writer and 1.7 nm at reader. Parametric study indicates that a trade off among the slit thickness (a), the distance of the slit to ABS (d) and thermal heater (t) should be optimized to achieve both large flying height reduction and small difference of flying height between reader and writer.     

Measurement of contact potential difference in head disk interface by readback signal spectrum

The contact potential difference leads to electrostatic interaction between the slider and disk in a hard disk drive. The effect of electrostatic force on slider’s flying height and flying stability becomes more significant with the decrease of flying height. A method of measurement of contact potential difference in head disk interface by readback signal spectrum is demonstrated in this paper. When a voltage with DC and AC was applied in the head disk interface, the amplitude of readback signal at the first harmonic frequency of applied AC voltage is proportional to the sum of contact potential difference and applied DC voltage. The contact potential difference in head disk interface is equal to the negative of DC voltage when the amplitude of readback signal at the first harmonic frequency is minimal.     

Study on head instability using Flying-QST tester for HDDs

We developed a tester consisting of minor-loop and major-loop quasi-static test (QST) units in order to better understand head instabilities under conditions where the head slider was flying on the disk. The minor-loop QST unit, composed of a spin-stand and an electromagnetic coil, was used to understand the mechanism of head instabilities caused by thermal stress due to flying-height control using a thermal actuator and caused by mechanical stress due to contact between the head and disk under flying conditions. The major-loop QST unit was used to investigate head damage in detail. We designed and fabricated the tester and conducted experiments that focused on thermal and mechanical stress. The results confirmed that the new method was effective for studying head instabilities at the head disk interface of hard disk drives (HDDs).     

Active-head slider with piezoelectric actuator using shear-mode deformation

The active-head slider technology for hard disk drive is one of the most promising means to decrease flying height. This paper describes a piezoelectric flying height control slider which has a faster dynamic response compared with conventional active-head sliders. This slider can be also adapted to the conventional slider-fabrication process. PZT layer located near the magnetic head has shear mode deformation by applying electric voltage between the upper and lower electrodes when the flying height of magnetic head needs to be decreased or increased. We fabricated a prototype with single crystal Si substrate for feasibility study. Our evaluation of the prototype revealed that the piezoelectric constant of the shear mode deformation was 0.88 nm/V, and the dynamic response was 50 kHz. The shape of the air bearing surface was optimized by simulations using a robust design method. We found that the stroke was 8 nm for an applied voltage of 11 V if the flying height was 11 nm with no deformation in PZT.     

Dynamic conformations of fluorocarbon molecules on magnetic hard disk surfaces with charged sites

To meet the demand of extremely high recording density of magnetic storage device, magnetic head is expected to reduce its flying height to sub 5 nm. Lubricant films in such system become more important and the conformation characteristics of lubricant molecules, which receive attractive forces both from the disk and the head, must be clarified for the stable flying of the head. In this report molecular dynamics simulations are carried out to investigate the conformation of lubricant molecules. The model is composed of solid surface and polar-ended fluorocarbon molecules. The surface has several reactive sites, which interact with polar end groups of fluorocarbon molecules. Varying the number of reactive sites, the processes that the reactive sites attract molecules are simulated. Results from the present simulations indicate that lubricant molecules tend to gathered and piled up. It is difficult to achieve 100% coverage.     

Investigation of dynamic head load and unload

Several air bearing designs were investigated with respect to dynamic Load and Unload (LUL) induced vibrations. Different ABS designs as well as design changes in the suspension of heads were analyzed using an LDV scanning system as well as a Capacitance Probe unit synchronized together. It was observed that the head and suspension exhibited either stable or unstable flying height behavior during the Load or Unload process over a range of velocities to and from the ramp. The results were used to determine a range of LUL speeds that prevented unstable head resonances as well as disk dings and scratches. Most of these head resonances were due to dynamic instabilities of the suspension and head system. The resonance points were investigated at the center and trailing edges (roll and pitch sensitivity) of the head and suspension. A Polytec LDV and Capacitance Probe were used to follow the stable and unstable flying behavior of the head while stationary and the ramp was allowed to move. Methods are discussed to minimize and dampen out the most severe head/suspension vibration levels. Simulation of the flutter of the integrated lead suspension traces due to air flow and possible ways to damp the flow induced resonance is also discussed     

The effect of write current on thermal flying height control sliders with dual heater/insulator elements

The effect of write induced pole tip protrusion on the magnetic spacing of the head/disk interface has to be taken into consideration as flying heights approach the spacing regime of a few nano-meters. Thermal flying height control (TFC) sliders are presently in common use in hard disk drives to control the flying height at the read/write element during drive operations. In this paper the flying characteristics of TFC sliders with dual heater/insulator elements are investigated. Simulation results are shown for situations where the write current is ??on?? and where the write current is ??off??. The effect of design parameters of two heater/insulator elements is studied to optimize the performance of TFC slider.