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Wang Y.,Xi'an Jiaotong University | Wang Y.,City University of Hong Kong | Wei X.,SAE Technologies Development Dongguan Co. | Zi Y.,Xi'an Jiaotong University | Tsui K.-L.,City University of Hong Kong
Shock and Vibration | Year: 2015

This paper investigated the instability of head-disk interface caused by the voice coil motor (VCM) end crashing the crash stop during the seeking of magnetic head. To make the whole process of that clear, an in situ measurement method based on maximum likelihood estimation and extended Kalman filter for seeking speed at component level was developed first and was then calibrated by a high speed camera. Given a crash between VCM end and crash stop that may be a consequence of the continuous increasing seeking speed, the seeking speed was carefully controlled by using our developed method to find a critical value that may induce vigorous head-disk interface instability. Acoustic emission sensor and laser Doppler vibrometer were used to capture the transient dynamic behaviors of magnetic head when the crash is happening. Damage analysis and mode identification were carried out to reveal the relationship between the damage patterns on disk surface and head dynamics. The results of this study are helpful to optimize the track seeking profile during the HDD operation, as well as the design of components such as head and head arm. © 2015 Yu Wang et al.


Zhao D.,SAE Technologies Development Dongguan Co. | Wei X.,SAE Technologies Development Dongguan Co. | Liu B.,SAE Technologies Development Dongguan Co. | Chen S.,SAE Technologies Development Dongguan Co. | And 2 more authors.
IEEE Transactions on Magnetics | Year: 2013

Thermal asperity (TA) sensor is used to investigate head disk interface (HDI) dynamics during operational shock. It is revealed that the output of TA sensor as a function of shock acceleration and back-off level. Air bearing modes being excited during operational shock indicates head-disk contact happens. The mechanisms and exciting sources of head-disk contact were explored by analyzing the TA sensor signal. Both experiment and simulation results show that motor base mode and head stack assembly (HSA) bending mode are the two most important contributions to head-disk contact. From this study, TA sensor is found to be useful for in situ monitoring of operational shock dynamics and, thus providing the strategies to improve shock-resistant performance. © 1965-2012 IEEE.


Zhao X.,CAS Guangzhou Institute of Energy Conversion | Zhao X.,University of Chinese Academy of Sciences | Mai Y.,CAS Guangzhou Institute of Energy Conversion | Luo H.,CAS Guangzhou Institute of Energy Conversion | And 4 more authors.
Applied Surface Science | Year: 2014

MoS2/poly (3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) composite (MoS2/P) was prepared through a facial and environmental friendly dip-coating method by dispersing nanostructured MoS 2 particles in PEDOT:PSS aqueous solution and subsequent filtering process. The characterization of XRD, FTIR, TGA, SEM and TEM revealed that the surface of rose-like MoS2 was homogeneously coated with a thin layer of PEDOT:PSS. After coating, MoS2/P composite showed an enhanced electric conductivity of 1.0 × 10-1 S/cm, about 5 times of that (2.2 × 10-2 S/cm) of the pristine MoS2. MoS 2/P composite electrode exhibited significantly improved electrochemical performances such as cyclability and rate capability. Half-cell tests showed that MoS2/P composite electrode delivered a reversible capacity of 712 mAh g-1 at a current density of 50 mA g-1 and retained 81% capacity after 100 cycles. At a higher current density of 200/300 mA g-1, it still retained a capacity of 439/363 mAh g -1 respectively, as compared to 191/140 mAh g-1 for the pristine MoS2. © 2013 Elsevier B.V. All rights reserved.


Wang G.-G.,Harbin Institute of Technology | Zhang H.-Y.,Harbin Institute of Technology | Zhou H.-F.,Harbin Institute of Technology | Kuang X.-P.,Harbin Institute of Technology | And 4 more authors.
Applied Surface Science | Year: 2010

There are higher technical requirements for protecting layer of magnetic heads and disks used in future high-density storage fields. In this paper, ultra-thin (2 nm thickness) tetrahedral amorphous carbon (ta-C) films were firstly prepared by filtered cathodic vacuum arc (FCVA) method, then a series of nitriding treatments were performed with nitrogen plasma generated using electron cyclotron resonance (ECR) microwave source. Here it highlighted the influence of nitrogen flow and applied substrate bias voltage on the structural characteristics of ta-C films during the plasma nitriding process. The chemical compositions, element depth distribution profiles, physical structures and bonding configurations of plasma-nitrided ta-C films were investigated by X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and UV-vis Raman spectroscopy. The experimental results show that the carbon nitride compounds (CNx) are formed in nitrogenated ta-C films in which the N content and its depth distribution depends on bias voltage to large extent rather than N2 flow. The N content of nitrogenated ta-C films can reach 16 at.% for a substrate bias of -300 V and a N2 flow of 90 sccm. With increasing nitrogen content, there is less G peak dispersion and more ordering of structure. Furthermore, appropriate nitriding treatment (substrate bias: -100 V, N2 flow: 150 sccm) can greatly increase the fraction of sp3 and sp3C-N bonds, but the values begin to fall when the N content is above 9.8 at.%. All these indicate that suitable ECR-assisted microwave plasma nitriding is a potential modification method to obtain ultra-thin ta-C films with higher sp3 and sp3C-N fractions for high-density magnetic storage applications. © 2009 Elsevier B.V. All rights reserved.


Zhao D.,SAE Technologies Development Dongguan Co. | Wei X.,SAE Technologies Development Dongguan Co. | Liu B.,SAE Technologies Development Dongguan Co. | Wang Y.,City University of Hong Kong | And 2 more authors.
Applied Mechanics and Materials | Year: 2013

This paper presents an investigation of spacing fluctuation characterization (SFC) of Hard Disk Drive (HDD) using thermal asperity (TA) sensor. Firstly, the spacing fluctuation monitored by TA sensor is correlated with that monitored by a Laser Doppler Vibrometer (LDV). Secondly, a series of experiments are conducted to study the factors affecting the spacing fluctuation, including disk distortion, head crown sensitivity, ZH sensitivity. Good disk assembly and small crown sensitivity and ZH sensitivity will be helpful to reduce spacing fluctuation. © (2013) Trans Tech Publications, Switzerland.


Wang Y.,Xi'an Jiaotong University | Wang Y.,City University of Hong Kong | Wei X.,SAE Technologies Development Dongguan Company | Liang X.,SAE Technologies Development Dongguan Company | And 2 more authors.
IEEE Transactions on Magnetics | Year: 2016

Recently, to achieve a stable slider dynamics and a high recording density, a contact (lubricant surfing) recording scheme has been proposed in the literature. However, under contact/surfing condition, the interaction between the head and the disk may bring new tribological issues, which has not been fully understood so far. To amend that, this paper experimentally investigates the relation between the interfacial dynamics and the wear behaviors of head/disk at different contact conditions. To investigate the interfacial dynamics, slider was then flown at different contact stages, and slider vibrations in both the vertical and the downtrack directions were monitored using two laser Doppler vibrometers. The wear depth of slider was inspected after the experiment to correlate interfacial dynamics at different contact stages. According to our results, a severe contact is not necessary to generate serious wear, which has strong correlation with the interfacial dynamics. Compared with the structure modes, the air-bearing modes were found to have a dominant impact on slider wear. Moreover, nonlinear vibration has a much more detrimental effect on the slider wear, although this type of vibration accompanies small amplitude at high-frequency band. This paper helps understand the wear mechanisms of slider under different slider/disk contact conditions, and thus expands new designs for surfing/contact recording technologies. © 1965-2012 IEEE.


Wang Y.,Xi'an Jiaotong University | Wang Y.,City University of Hong Kong | Wei X.,Xi'an Jiaotong University | Wei X.,SAE Technologies Development Dongguan Company | And 4 more authors.
IEEE Transactions on Magnetics | Year: 2016

The electrostatic force at head-disk interface (HDI) becomes increasingly significant when the head-disk clearance is dropping into 1 nm scheme. Therefore, detecting and eliminating the electric potential in the HDI is a critical task for hard disk drives. To that end, this paper proposed an in situ measurement method for electric potential at HDI using a thermal asperity (TA) sensor. When calibrating the electric potential, both dc and ac components of the external voltage were supplied to the disk. As a result, the output of the TA sensor to the first harmonic of the ac component was linearly increasing with the decrease in the dc components. Experimental results show that this method is more efficient and flexible than the traditional methods. © 1965-2012 IEEE.


Patent
SAE Technologies Development Dongguan Co. | Date: 2013-05-06

A flexure for a suspension of a head gimbal assembly includes a substrate layer, a dielectric layer formed thereon, a conducting layer formed on the dielectric layer, and an insulating cover layer covered on the conducting layer, wherein at least one window is configured at a surface of the insulating cover layer thereby a portion of the conducting layer is exposed, and an antistatic adhesive is adhered to at least one side wall of the window and contacted with the conducting layer. The new structure of the flexure can avoid or eliminate electro-static discharges enduringly without dipping water. A head gimbal assembly and a disk drive unit with the same, a manufacturing method for the flexure are also disclosed.


Patent
SAE Technologies Development Dongguan Co. | Date: 2011-06-27

A bonding method of row bars comprises step (1), attaching a flexible member on a flat bottom surface of a pressurized member; step (2), applying a wax layer on a support surface of a support device; step (3), disposing a row bar on the support surface with the wax layer; and step (4), controlling the pressurized member to fall down, so as to press and even out the row bar. The present invention can make the row bar obtain a desired bending degree that is beneficial to the subsequent lapping process, and in turn, improve the quality of the sliders produced from the row bar, and finally improve the read/write performance of the sliders.


PubMed | Fudan University, SAE Technologies Development Dongguan Co., University of Illinois at Chicago and Macau University of Science and Technology
Type: Journal Article | Journal: Applied microbiology and biotechnology | Year: 2016

Angiogenesis provides necessary nutrients and oxygen for tumor growth and metastasis; thus, every stage of angiogenesis process is the potential target for cancer therapies. Ursolic acid (UA) is reported to decrease tumor burden through anti-angiogenesis pathway, but its poor water solubility greatly limits its efficiency and clinical application. Here, a simple method for preparing UA-loaded chitosan nanoparticles (CH-UA-NPs) with anti-angiogenesis and anti-tumor activity was demonstrated. In vitro, CH-UA-NPs could significantly inhibit the proliferation, migration, and tube formation of human umbilical vascular endothelial cells (HUVECs). After uptake by HUVECs, CH-UA-NPs were mainly localized in lysosomes and mitochondria, but not nuclei. CH-UA-NPs induced the destruction of lysosome membrane integrity, collapse of mitochondrial membrane potential, and reorganization of cell cytoskeleton. All these changes led to the apoptosis or necrosis in HUVECs. In vivo, CH-UA-NPs could inhibit the angiogenesis in chicken chorioallantoic membrane (CAM) model and H22 xenograft model. Notably, comparing with free UA, such synthesized CH-UA-NPs could save about tenfold of UA doses, implying that this could significantly decrease the side effects induced by high doses of UA in biological organism. Our data showed that CH-UA-NPs and this nanoparticle-based drug delivery system could be as a potential drug candidate foranti-angiogenesis treatment.

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