Robust Optimum Design of Thrust Hydrodynamic Bearings for Hard Disk Drives

This paper describes the robust optimum design which combines the geometrical optimization method proposed by Hashimoto and statistical method. Recently, 2.5″ hard disk drives (HDDs) are widely used for mobile devices such as laptops, video cameras and car navigation systems. In mobile applications, high durability towards external vibrations and shocks are essentials to the bearings of HDD spindle motor. In addition, the bearing characteristics are influenced by manufacturing error because of small size of the bearings of HDD. In this paper, the geometrical optimization is carried out to maximize the bearing stiffness using sequential quadratic programming to improve vibration characteristics. Additionally, the bearing stiffness is analyzed considering dimensional tolerance of the bearing using statistical method. The dimensional tolerance is assumed to distribute according to the Gaussian distribution, and then the bearing stiffness is estimated by combining the expectation and standard deviation. As a result, in the robust optimum design, new groove geometry of bearing can be obtained in which the bearing stiffness is four times higher than the stiffness of conventional spiral groove bearing. Moreover, the bearing has lower variability compared with the result of optimum design neglecting dimensional tolerance.

Optimization of passive control performance for different hard disk drives subjected to shock excitation

Laptop personal computers(LPCs) and their components are vulnerable devices in harsh mechanical environments. One of the most sensitive components of LPCs is hard disk drive(HDD) which needs to be protected against damages attributable to shock and vibration in order to have better magnetic read/write performance. In the present work, a LPC and its HDD are modeled as two degrees of freedom system and the nonlinear optimization method is employed to perform a passive control through minimizing peak of HDD absolute acceleration caused by a base shock excitation. The presented shock excitation is considered as half-sine pulse of acceleration. In addition, eleven inequality constraints are defined based on geometrical limitations and allowable intervals of lumped modal parameters. The target of the optimization is to reach optimum modal parameters of rubber mounts and rubber feet as design variables and subsequently propose new characteristics of rubber mounts and rubber feet to be manufactured for the HDD protection against shock excitation. The genetic algorithm and the modified constrained steepest descent algorithm are employed in order to solve the nonlinear optimization problem for three widely-used commercial cases of HDD. Finally, the results of both optimization methods are compared to make sure about their accuracy.

OPTIMAL TRACK SEEKING CONTROL OF DUAL-STAGE ACTUATOR FOR HIGH DENSITY HARD DISK DRIVES

Based on generalized the variation method, by introducing Hamilton function and Lagrange multiplier, this paper proposed a linear quadratic optimal control strategy for an incomplete controllable system with fixed terminal state and time. Applying the proposed optimal control to the simple two-input dual-stage actuator magnetic head positioning system with three degrees-of-freedom, the simulation results show that the system has no residual vibration at the terminal position and time, which can reduce the total access time during head positioning process. To verify the validation of the optimal control strategy of three degrees-of-freedom spring-mass models in actual magnetic head positioning of hard disk drives, a finite element model of an actual magnetic head positioning system is presented. Substituting the optimal control force from simple three degrees-of-freedom spring-mass models into the finite element model, the simulation results show that the magnetic head also has no residual vibration at the end of track-to-track travel. That is to say, the linear quadratic optimal control technique based on simple two-input dual- stage actuator system with three degrees-of-freedom proposed in this paper is of high reliability for the industrial application of an actual magnetic head positioning system.

Numerical Investigation of Flow Structure Interaction Coupling Effects in Hard Disk Drives

This paper studies the flow structural interaction (FSI) within a hard disk drive (HDD) through the use of a novel coupling method. The interaction studied was the fluid induced vibration in the HDD. A two step coupling approach was used, where the fluid and structural components were solved sequentially. The result obtained was a ratio of 0.65 between the vibration amplitudes of a fixed head stack assembly (HSA) and a moving HSA. The ratio was next applied on a real 3.5 inch HDD, to allow the parameter to be further improved upon. A new benchmark index of 0.69 was developed from this. This parameter may allow future researchers to model the out of plane vibrations of a HSA easily, saving precious time. A 31% more accurate simulation of FSI within 3.5 inch HDD at 15000 rpm is achieved by the use of this new coupling method and benchmark index.

Heat Source Analysis of Hard Disk Drives with Different Wall Conditions using Infrared System

Increasing performance parameters of hard disk drive (HDD) such as higher capacity and faster data access speed with decreasing physical size make HDD more susceptible to thermal effects. Contact temperature measurement using thermocouple is not suitable for the rotating platter of HDD. Heat analysis using simulation software requires accurate initial parameter setting such as thermal (initial & boundary) conditions of certain regions. Temperature measurement using infrared (IR) system avoids these limitations;it is non-contact, responsive and does not require initial parameter setting. Thermal pattern distribution can be studied from the thermal images. However, emissivity of the target has to be known and calibration of the system is essential for accurate temperature reading. This paper showed that temperature within the HDD increases with ambient temperature and time, but the thermal distribution pattern in the HDD was not affected by different ambient temperatures. Three wall boundary conditions were conducted to study the thermal distribution pattern in the HDD. A solution was then proposed based on the results obtained from the experiments to improve the heat transfer rate and steady state temperature, and reduce the detrimental effects from high thermal generation in future prototypes. Another important finding was that the averaged temperature of the head cap was generally higher compared to that of the disk, as the spindle motor is the primary heat source within the HDD. Heat source analysis of HDD with IR system allows designers to have better visibility of the temperature generated in different components of the HDD. Proper cooling may enhance disk life as well as ensure the stability and integrity of the system.

Vibration Response Characteristics against the Radial and Axial Shocks on Small Size Hard Disk Drive Spindle Supported by Oil Film Bearings

This paper describes the experimental study on shock response of FDB （fluid dynamic bearing） spindle for HDDs （hard disk drives）. The FDBs are widely used as rotating shaft support elements for HDD spindle motors. Recently, the opportunity for the HDD spindle motors exposed to external vibration has been increasing because the HDDs are used for various information related equipment such as mobile PCs （personal computers）, video cameras, car navigation systems and so on. Hence, the rotating shaft has a possibility to come in contact with the bearing by external shocks and it causes wear or seizure to the bearing surface. To avoid the problem, it is extremely important to know how the spindle moves against the large shock on HDDs experimentally. However, as far as the authors know, there are few experimental studies treating the shock response of HDD spindles. In this paper, firstly, we propose a new test rig and experimental method for shock response of FDB spindles. Then the shock tests against the radial and axial disturbance on FDB spindle for 2.5＂ HDD are conducted. Finally, the experimental results of shock response waveforms and maximum displacement of disk are shown.

Power-Law Distributions in Hard Drive Behavior

Taking into account the fact that the computer systems, as the implementations of Turing machine, are physical devices, the paper shows considerations in which hard drive behavior will be presented in terms of statistical mechanics. Because computer is a machine, its analysis cannot be based only on mathematical models apart of physical conditions. In the paper it will be presented a very narrow part this problem – an analysis of hard drive behavior in the context of the power-law distributions. We will focus only on four selected hard drive parameters, i.e. the rate of transfer bytes to or from the disk during the read or write, the number of pending requests to the disk and the rate of read operations. Our research was performed under the Windows operating system and this allows to make a statistical analysis for the possible occurrence of power-laws representing the lack of characteristic scale for considered processes. This property will be confirmed in all analyzed cases. A presented study can help describing the behavior of the whole computer system in terms of physics of computer processing.

多层坚硬顶板特厚煤层综放工作面小煤柱护巷技术

为研究小煤柱护巷巷道的稳定性及其阻隔同层位邻近采空区灾害的特征,以大同矿区石炭系坚硬顶板特厚煤层开采为工程背景,采用理论分析、实验研究、数值模拟等研究方法,从小煤柱护巷巷道的稳定性和其是否具有阻隔同层位邻近采空区有害气体能力2个角度,综合分析小煤柱的合理尺寸及其在不同采动阶段渗透率的演化特征。针对同忻煤矿石炭系煤层8210工作面沿空掘巷小煤柱开采具体的开采条件,建立了双关键层采场内外应力场叠加的力学模型,推导出双关键层条件下沿空掘巷小煤柱合理尺寸的计算关系式,理论确定8210工作面小煤柱合理尺寸为6.0 m;应用DJG–Ⅱ型煤岩渗流测试装备,研究不同采动阶段小煤柱渗透率演化特征,试验确定在第3采动阶段小煤柱渗透率较初始渗透率增大了23倍,该阶段小煤柱基本失去了阻隔邻近采空区有害气体的能力。根据理论研究结果,现场选取6 m小煤柱进行工业性试验;根据试验研究结果,开采试验过程中对小煤柱进行了改性降透措施,在小煤柱表面及顶板距煤柱帮1500 mm范围内喷射厚层混凝土(100 mm)。实践表明:工作面回采过程中小煤柱护巷的回采巷道发生了一定的变形量,但是巷道变形在安全可控范围之内,巷道稳定,可实现安全回采;开采过程中8210工作面上隅角CH4气体浓度远低于邻近8305工作面采空区CH4气体浓度,表明小煤柱经过改性降透后具备了阻隔同层位邻近采空区有害气体的能力;开采实践也进一步验证了理论和试验研究成果的合理性和科学性。研究成果可以为类似条件下小煤柱护巷技术的推广应用提供参考。

渗层强化的果园运输机驱动轮耐磨性能

为解决牵引式果园运输机绳-轮驱动系统驱动轮绳槽磨损严重而导致牵引滑移失效的问题,该研究对基于渗层强化的果园运输机驱动轮耐磨性能进行了分析。首先通过ANSYS软件探究了驱动轮表面应力应变随其硬度的变化规律;随后采用热扩散沉积(thermal diffusion, TD)技术对45钢驱动轮进行了渗钒与渗硼处理,并对渗层的显微结构、力学性能和摩擦磨损特性进行了对比分析,最后利用运输机模拟台架对渗层强化后驱动轮的应用性能进行了测试。结果表明:驱动轮渗钒层和渗硼层厚度分别为20.9和97.3μm,均与基材结合较好;且由于渗层中碳化钒、硼化铁等硬质相的存在,渗钒层与渗硼层硬度分别达到22.08和13.45 GPa,较未处理前提升3~4倍;往复摩擦试验下渗钒层与渗硼层表面摩擦系数分别为0.47、0.44,较45钢分别下降19%、24%。运输机模拟台架应用性能测试表明,干摩擦下渗钒与渗硼处理后驱动轮的平均磨损量较45钢分别降低了88%和81%,其中渗钒驱动轮表面磨损较小;油润滑下渗钒与渗硼处理后驱动轮的平均磨损量较45钢分别降低了92%和85%。综上,热扩散渗钒与渗硼处理均可大幅提高驱动轮抗磨性,其中渗钒层具有更高的硬度与耐磨性,但在应用时需进行实时油润滑,更适合对满足定时维护条件下的驱动轮进行强化;而渗硼层耐磨性虽有所降低,但可在干摩擦下使用,更适合对野外山地环境下无法满足润滑的驱动轮进行强化。该研究结果可为改善牵引式果园运输机驱动轮耐磨性提供可行技术方案。

软硬资源协同驱动视角下高校新型研发机构产学研合作现状、问题及发展路径研究

构成创新创业教育教学和人才培养体系等软硬资源的协同驱动对于优化高校教育教学和人才培养制度体系、助力高校新型研发机构产学研合作具有重要意义。通过梳理国内外高校新型研发机构软硬资源研究现状发现,软资源和硬资源有着互利共生又相得益彰的协同关系,软硬资源协同驱动对于助力高校新型研发机构产学研合作有重要意义。在此基础上,进一步指出中国高校新型研发机构产学研合作在主体资源、发展定位、政策制度以及分配机制上仍存在一系列问题,具体体现为高校新型研发机构的顶层设计和布局尚不完善、分布不平衡,在发展定位软资源与科研平台和设备等硬资源投入方面出现偏差等,这主要由于软硬资源的各自功能发挥和协同驱动作用程度都未能满足产学研合作的需要。因此,需要完善产学研合作的生态系统,在资源共享的前提下,明确产学研各主体的功能定位,构建管理体制、人才培养体系完善的软硬资源协同驱动产学研合作模式。

综放面“双硬”煤层临空煤柱宽度及承载强度校核

具有“双硬”特征煤层的工作面其护巷煤柱的极限尺寸确定与常规工作面有所不同。以榆树岭煤矿505工作面沿空掘进巷道为背景,首先测试了煤岩样的力学性质和不同高径比煤样的抗压强度,得到了不同高径比煤样峰值强度曲线;其次分析了沿空掘巷覆岩结构模型,建立了沿空掘巷护巷煤柱顶板力学模型,得到了不同宽度煤柱所受的载荷应力;建立了不同高宽比煤柱的数值模型,得到了不同高宽比煤柱的极限强度校核公式;最后通过对比不同宽度煤柱所受的载荷应力和极限强度,得出4m宽度的煤柱即可满足支护要求,并在此基础上提出了沿空掘进巷道支护工艺。现场监测结果表明,煤柱宽度为4m时,巷道整体变形量较小,巷道稳定性得到有效维护。研究结果可为小煤柱护巷宽度的确定提供参考。

噪声激励下的硬盘频响特性研究和性能预测模型

针对服务器硬盘在高噪声环境下性能下降问题,设计了一种试验方法来分析噪声激励下硬盘性能损失的敏感度特性。通过编程模拟不同频率和强度的1/9倍频程带宽的均匀随机噪声,测试硬盘在噪声激励下产生的性能损失。通过机理分析和试验数据分析,建立回归方程,提出敏感度(K)的数学模型。建立了预测硬盘性能损失的数学模型,基于服务器机箱内散热风扇产生的真实噪声信号可计算出硬盘性能损失率。在多种场景的检验中发现预测模型的结果非常接近实际结果,证明此方法是一种非常准确的分析和预测手段,为服务器系统的声学设计提供有效的量化参考。

基于SMART数据模式的HDD硬盘状态预测方法

硬盘广泛应用于各类信息系统中,其工作状态预测对信息系统的正常运行管理有着重要意义。现有基于SMART(Self Monitoring Analysis and Reporting Technology)属性的机器学习预测算法为保证其通用性,普遍选取部分典型属性作为特征,带来一定的信息丢失。在分析SMART数据特点的基础上,提出数据模式分类后再进行机器学习预测的SMART数据处理方法。实际测试结果表明,经分类处理后,采用简单的机器学习算法即可获得与强分类器接近的性能,同时,该方法可有效简化SMART数据机器学习时的特征选择过程,有效降低算法的资源消耗。

机械硬盘加速寿命试验及状态监测技术研究

机械硬盘的健康状态监测和诊断对于企业的安全可靠运行和节约运维成本起着至关重要的作用。首先,分析了硬盘的基本组成和不同环境应力下的故障模式和机理;其次,根据实际运行环境制定了加速寿命试验,并在试验过程中对硬盘的SMART数据进行采集和存储;最后,经过对比和分析发现了该型号硬盘的敏感SMART参数,并发现寻道出错率具有明显的退化趋势,可用于故障预警和预测。

基于AE-LSTM的多目标硬盘故障预测方法

硬盘故障预测是在故障发生前发出预警,避免数据丢失或服务中断,提高数据中心的可靠性和安全性;然而,大多数故障预测模型将硬盘故障问题转化为二分类任务,忽略了硬盘故障是渐变过程的,并且缺乏故障诊断功能;因此,提出了一种基于AE-LSTM的硬盘故障预测框架,实现多目标任务:硬盘健康状态分级、硬盘剩余使用寿命预测、硬盘故障诊断;采用回归决策树模型智能化对硬盘健康状态进行标记,并通过AE-LSTM模型提取鲁棒的隐藏变量,构建剩余使用寿命预测模型和硬盘健康状态分级模块,根据AE模块的输入输出差异进行硬盘故障诊断;在Backblaze公开数据集上,对比了RF、LSTM和AE-LSTM三种算法,实验结果证实了AE-LSTM算法在多目标硬盘故障预测中的有效性和优势。

2023年探矿工程十大新闻

1我国第一口万米深地科探井开钻2023年5月30日,我国第一口万米科探井——深地塔科1井在新疆塔里木盆地开钻。这标志着我国向地球深部探测技术系列取得新的重大突破,钻探能力开启“万米时代”,将为我国未来的科学研究和油气资源开发提供重要的基础和支持。

Design of Intersample Response in a Hard Disk Control System

The present paper discusses a design method for the head position in a Hard Disk Drive （HDD） control system. In the HDD control system, the sampling interval of the head position is constrained because of the hardware specifications, but the hold interval of the control input is not constrained. In the present study, a multirate control system is designed, in which the sampling and the hold intervals are not equal. A multirate control law, which stabilizes a closed-loop system, is extended using newly introduced parameters such that the sample response of the plant output is maintained. Furthermore, intersample ripples in the steady state are eliminated using the new design parameters, which can be selected independently of the sample response. As a result, the intersample response can be improved independently of the sample response. The proposed method is applied to a benchmark problem of an HDD system, and its effectiveness is demonstrated.

大断面硬岩巷道炮掘快速施工技术研究

为了解决采区系统巷道掘进效率低、准备进度慢的难题,分别从支护设计、爆破参数、设备配备、排矸效率、施工质量以及组织管理等方面分析了影响掘进效率的原因,提出了大断面硬岩巷道“差异化支护设计—设备配备与改进—线性聚能爆破—柔性连续排矸系统—施工及劳动组织保障”的岩巷炮掘快速施工技术,并在潘三矿西三下部采区轨道大巷进行了工程实践,形成了“液压钻车打眼—线性聚能爆破—安全高效支护—柔性连续排矸”的岩巷炮掘快速施工作业线。实践表明:大断面硬岩条件下的岩巷炮掘快速施工技术能够实现“快速打眼、高效进尺、连续排矸、有效支护”的安全高效掘进,进尺效率提高了126%,月进尺达到86 m,人工工效提高至2.04 m/(人·月),显著提高了岩巷炮掘的进尺效率。