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Design and Construction of Magnetic Storage Devices
Published in Bharat Bhushan, Handbook of Micro/Nano Tribology, 2020
Hirofumi Kondo, Hiroshi Takino, Hiroyuki Osaki, Norio Saito, Hiroshi Kano
Recently, thin-layered particulated disks, previously discussed in the particulate tape section, with a capacity of more than 100 MB are available for high-density applications. Rotation speed is so high that these drive systems use a flying hard disk head not a spherical surface contour which has been used for MFD. Over the years, the floppy disks used to be a major distribution tool, but nowadays CD-ROM has taken their role; therefore, the need for an MFD with more than 100 MB in capacity has become pressing. Table 12.3 shows typical characteristics of four new drives that are now available or will soon be available and the 3.5-in, floppy disk drive. Double-coating metal particulated disk previously discussed in the particulate tape section, are used for these applications. The technology adopted in Zip drive was mostly transferred from the hard disk drive, and that made the entire system achieve its storage capacity as much as 100 MB. Higher rotational speed and linear density increased the data transfer rate and the unique servo system and narrow track width gained the area density. If one considers of the hard disk drive with conventional MIG head, its capacity is nearly 1 GB on a single 3.5-in, platter, ten times that of the Zip drive in capacity. Even though the floppy disk is removable media and easy to deform by environmental changes in a microscopic sense, still there is room to get close to the hard disk drive system in its capacity.
Memory Organisation
Published in Pranabananda Chakraborty, Computer Organisation and Architecture, 2020
Portability: A non-removable disk permanently mounted in the disk drive is a sealed pack, and it is used as one unit. All the hard disks used in today’s computers (except mainframes) are non-removable disks. A removable disk is mounted in a disk drive. The disk drive consists of an arm with the read/write head attached to it, a shaft that rotates the disk, and the entire electronic circuits required for transferring (input/output) binary data. The removable disk may be of single platter (CDs) or may be of multiple platter (disk pack used in a mainframe large system). The removable disk can be taken away manually from the disk drive and replaced with another disk on the same drive even when the computer is on. The advantage of this type of disk is that an unlimited amount of data is available with a limited number of disk systems. Furthermore, a disk may be moved from one computer system, and it can be mounted in another compatible system.
Emerging Spintronic Memories
Published in Evgeny Y. Tsymbal, Igor Žutić, Spintronics Handbook: Spin Transport and Magnetism, Second Edition, 2019
Stuart Parkin, Masamitsu Hayashi, Luc Thomas, Xin Jiang, Rai Moriya, William Gallagher
Traditional computing systems use a complex hierarchy of volatile and non-volatile (NV) memory technologies (largely to manipulate data) and data-storage technologies (largely to store data) to achieve a reasonable balance of performance, cost, and endurance. This leads to considerable complexity in operating systems and software applications, which adds cost and decreases reliability. Magnetic disk drives are the cheapest form of non-archival data storage with a cost about 10–100 times lower per bit than solid state memory technologies. Disk drives are capable of inexpensively storing huge amounts of data: typical capacities exceed several hundred gigabytes today. However, hard disk drives (HDDs) have a limited mean time to failure. A hard drive includes a fixed read/write head and a moving medium on which data is written. Devices with moving parts always are intrinsically unreliable with a possibility of mechanical failure and complete loss of stored data.
Explore deep auto-coder and big data learning to hard drive failure prediction: a two-level semi-supervised model
Published in Connection Science, 2022
Yan Ding, Yunan Zhai, Yujuan Zhai, Jia Zhao
However, current SMART-based approaches are far from enough to cope with new requirements and challenges in the aspects of the fineness for efficiency and the accuracy for performance. Besides, seizing the opportunity of exploring big data and semi-supervised deep learning idea to address the problem is impractical in the reality. Thus, the proposed problem is how we can efficiently exploit deep learning and large amounts of SMART data of snapshots dataset to mitigate the failure prediction problem of hard disk drives. SMART defines and monitors an array of parameters and attributes of HDDs. However, not all these attributes can be used as features for prediction model in terms of availability and efficiency. Through data preprocessing including de-noising, filtering and feature selection, the original SMART dataset S is converted to the dataset D. Here, is a vector of q-dimension and composed of q metrics (feature attributes) of a single hard disk drive. The x of a snapshot can be used to represent an instantaneous state of the corresponding hard disk drive at that time.
Heusler alloys for spintronic devices: review on recent development and future perspectives
Published in Science and Technology of Advanced Materials, 2021
Kelvin Elphick, William Frost, Marjan Samiepour, Takahide Kubota, Koki Takanashi, Hiroaki Sukegawa, Seiji Mitani, Atsufumi Hirohata
Spintronics has been initiated by the discovery of giant magnetoresistance (GMR) by Fert et al. [1] and Grünberg et al. [2] independently. A GMR device consists of a sandwich structure of a ferromagnet (FM)/non-magnet (NM)/FM multilayer, where an external magnetic field can align the FM magnetisations in parallel to achieve a low-resistance state as compared with a high-resistance state with antiparallel magnetisations without a field application. The first-generation spintronic devices are based on magnetoresistive (MR) junctions, which have been used very widely [3,4], e.g., a read head in a hard disk drive (HDD) [5] and a cell in a magnetic random access memory (MRAM) [6]. The critical measure of efficient magnetic transport in these devices is an MR ratio, which is defined by
Development of a PEMFC-based heat and power cogeneration system
Published in International Journal of Green Energy, 2018
System control and data acquisition (SCADA) subsystem: The hardware of the SCADA subsystem adopted by the current study is shown in Figure 5, and Figure 6 contains the SCADA platform software structure. In Figure 5, the SCADA of the current fuel cell CHP system is performed by an ICPDAS programmable automation controller (PAC) and appropriate modules for measuring system parameters like fuel cell voltage, current, temperature, pressure, and controlling devices like solenoid valve, air pump, hydrogen circulation pump, and relays. PAC is more like a combination of personal computer (PC) and programmable logic controller (PLC). It runs both system control and HMI on the same machine. A fanless compact flash is used for massive data storage to replace hard disk drive.