Hitachi, Ltd. is a Japanese multinational conglomerate company headquartered in Chiyoda, Tokyo, Japan. It is the parent of the Hitachi Group and forms part of the DKB Group of companies. Hitachi is a highly diversified company that operates eleven business segments: Information & Telecommunication Systems, Social Infrastructure, High Functional Materials & Components, Financial Services, Power Systems, Electronic Systems & Equipment, Automotive Systems, Railway & Urban Systems, Digital Media & Consumer Products, Construction Machinery and Other Components & Systems.Hitachi is listed on the Tokyo Stock Exchange and is a constituent of the Nikkei 225 and TOPIX indices. It is ranked 38th in the 2012 Fortune Global 500 and 129th in the 2012 Forbes Global 2000. On January 21, 2014, numerous tech articles around the globe published findings from the cloud storage provider Backblaze that Hitachi hard disks are the most reliable among prominent hard disk manufactures. Wikipedia.
Mukherjee A.,Hitachi Ltd.
IEEE Journal on Selected Topics in Signal Processing | Year: 2013
This work investigates the diffusion of cooperative behavior over time in a decentralized cognitive radio network with selfish spectrum-sensing users. The users can individually choose whether or not to participate in cooperative spectrum sensing, in order to maximize their individual payoff defined in terms of the sensing false-alarm rate and transmit energy expenditure. The system is modeled as a partially connected network with a statistical distribution of the degree of the users, who play their myopic best responses to the actions of their neighbors at each iteration. Based on this model, we investigate the existence and characterization of Bayesian Nash Equilibria for the diffusion game. The impacts of network topology, channel fading statistics, sensing protocol, and multiple antennas on the outcome of the diffusion process are analyzed next. Simulation results that demonstrate how conducive different network scenarios are to the diffusion of cooperation are presented for further insight, and we conclude with a discussion on additional refinements and issues worth pursuing. © 2013 IEEE.
Fujisaki Y.,Hitachi Ltd.
Japanese Journal of Applied Physics | Year: 2013
The integration limit of flash memories is approaching, and many new types of memory to replace conventional flash memories have been proposed. Unlike flash memories, new nonvolatile memories do not require storage of electric charges. The possibility of phase-change randomaccess memories (PCRAMs) or resistive-change RAMs (ReRAMs) replacing ultrahigh-density NAND flash memories has been investigated; however, many issues remain to be overcome, making the replacement difficult. Nonetheless, ferroelectric RAMs (FeRAMs) and magnetoresistive RAMs (MRAMs) are gradually penetrating into fields where the shortcomings of flash memories, such as high operating voltage slow rewriting speed, and limited number of rewrites, make their use inconvenient. For instance, FeRAMs are widely used in ICs that require low power consumption such as smart cards and wireless tags. MRAMs are used in many kinds of controllers in industrial equipment that require high speed and unlimited rewrite operations. For successful application of new non-volatile semiconductor memories, such memories must be practically utilized in new fields in which flash memories are not applicable, and their technologies must be further developed. © 2013 The Japan Society of Applied Physics.
Kawahara T.,Hitachi Ltd.
IEEE Design and Test of Computers | Year: 2011
Editor's note: Nonvolatile embedded memories may open the door to new computing paradigms based on "normally-off and instant-on" operation. This article covers recent trends of spin-transfer-torque RAM technology, an emerging class of nonvolatile memory, and discusses its impact on the different layers of computer system hierarchy. © 2006 IEEE.
Agency: Cordis | Branch: FP7 | Program: ERC-SyG | Phase: ERC-2013-SyG | Award Amount: 9.65M | Year: 2014
Organic semiconductors are enabling flexible, large-area optoelectronic devices, such as organic light-emitting diodes, transistors, and solar cells. Due to their exceptionally long spin lifetimes, these carbon-based materials could also have an important impact on spintronics, where carrier spins, rather than charges, play a key role in transmitting, processing and storing information. However, to exploit this potential, a method for direct conversion of spin information into an electric signal is indispensable. Spin-charge conversion in inorganic semiconductors and metals has mainly relied on the spin-orbit interaction, a fundamental relativistic effect which couples the motion of electrons to their spins. The spin-orbit interaction causes a flow of spins, a spin current, to induce an electric field perpendicular to both the spin polarization and the flow direction of the spin current. This is called the inverse spin Hall effect (ISHE). We have very recently been able to observe for the first time the inverse spin-Hall effect in an organic conductor. This breakthrough raises important questions for our understanding of spin-charge conversion in materials with intrinsically weak spin-orbit coupling. It also expands dramatically the range of materials and structures available to address some currently not well understood scientific questions in spintronics and opens opportunities for realising novel spintronic devices for spin-based information processing and spin caloritronic energy harvesting that make use of unique properties of hybrid, organic-inorganic structures. The main objective of the proposed research is to take spintronics to a level that inorganic spintronics cannot reach on its own. The project is based on new theoretical and experimental methodologies arising at the interface between two currently disjoint scientific communities, organic semiconductors and inorganic spintronics, and aims to exploit synergies between chemistry, physics and theory.
Hitachi Ltd. | Date: 2016-01-06
One or more storage systems are connected to one or more storage boxes comprising multiple storage devices. Multiple storage areas provided by one or more storage boxes include an allocated area, which is a storage area that is allocated to a virtual volume, and an empty area, which is a storage area that is not allocated to any logical volume. Multiple owner rights corresponding to multiple storage areas are set in one or more storage systems. A storage system having an empty area owner right changes an empty area to the allocated area by allocating the empty area. In a case where a configuration change (a relative change in the number of storage boxes with respect to the number of storage systems) is performed, a first storage system that exists after the configuration change sets, in the first storage system, either more or fewer owner rights than the owner rights, which have been allocated to the first storage system before the configuration change.