Cooling Design for the Next Generation Optical Disc Drive

Author(s):  
Takayuki Fujimoto ◽  
Nobuyuki Isoshima ◽  
Hiroyuki Toyoda ◽  
Yoshiaki Yamauchi ◽  
Hitoshi Matsushima ◽  
...  

Recently, the data transfer rate and the memory capacity of optical disc drives have been increasing dramatically. To obtain the high data transfer rate and greater memory capacity, the disc rotation speed and the laser power also need to be increased and these cause an increase in the temperature of the laser diode. Therefore, to develop the next generation optical disc drives, an enhanced cooling system is indispensable for the optical pick-up unit that contains the laser diode. As the temperature of the pick-up unit is influenced by the inside air flow induced by the disc rotation, it is quite necessary to grasp the velocity and temperature distribution inside the drive, and also the influence of the disc rotation speed on the temperature of the pick-up unit. Hence we applied PIV measurements and CFD simulations to visualize the flow field and the internal temperature. Then, during the actual disc recording process we measured the temperature of the pick-up unit and the internal air of the drive. As a result, we made clear the dependence of the disc rotation speed on the pick-up unit temperature. In addition, as an example for next generation optical disc drives, we evaluated the cooling system applying a small axial fan inside the drive and confirmed the validity of this fan system.

2002 ◽  
Vol 41 (Part 1, No. 3B) ◽  
pp. 1804-1807 ◽  
Author(s):  
Gakuji Hashimoto ◽  
Hiroki Shima ◽  
Kenji Yamamoto ◽  
Tsutomu Maruyama ◽  
Takashi Nakao ◽  
...  

2021 ◽  
Vol 1 (132) ◽  
pp. 136-144
Author(s):  
Volodymyr Khandetskyi ◽  
Dmutro Sivtsov ◽  
Kostjantun Panin

Analysis of new technologies IEEE 802.11ac/ax of wireless networks showed that increasing their noise immunity is an actual task. The article studies the efficiency of fragmented data frames transmission. Comparison of the efficiencies in the case of retransmission of the corrupted original frame and in the case of its fragmentation in a wide range of the physical data transfer rates is carried out.


1989 ◽  
Vol 66 (12) ◽  
pp. 6138-6143 ◽  
Author(s):  
Harukazu Miyamoto ◽  
Toshio Niihara ◽  
Hirofumi Sukeda ◽  
Masahiko Takahashi ◽  
Takeshi Nakao ◽  
...  

Photonics ◽  
2019 ◽  
Vol 6 (2) ◽  
pp. 70
Author(s):  
Hirayama ◽  
Fujimura ◽  
Umegaki ◽  
Tanaka ◽  
Shimura

Holographic memory is currently attracting attention as a data storage system capable of achieving a data transfer rate of about 105~106105~106 times that of an optical disc such as Blu-ray disc. In conventional holographic memory, data is generally recorded by optical writing using volume holograms. However, a volume hologram has the problem not only that it is required to have high mechanical accuracy of a system and low coefficient of thermal expansion of a recording medium, because reconstruction tolerance is extremely low, but also that duplicating time efficiency is poor because whole data cannot be recorded at once. In this paper we proposed surface holographic memory that achieved a high data transfer rate, stable readout performance, and collective duplication by expressing holograms with fine surface asperity. Furthermore, the theoretical formulas of recording and reconstruction processes in the proposed system were derived and the reconstruction characteristics of the hologram were evaluated by numerical simulation. As a result, the proposed method generated reconstructed image readout with sufficient signal for a single page recording. However, the reconstructed image had noise, which was particular to a surface holographic memory.


1997 ◽  
Author(s):  
Stephan Spielman ◽  
Bruce V. Johnson ◽  
Greg A. McDermott ◽  
Michael P. O'Neill ◽  
C. Pietrzyk ◽  
...  

1993 ◽  
Vol 32 (Part 1, No. 11B) ◽  
pp. 5411-5416 ◽  
Author(s):  
Ryoichi Arai ◽  
Makoto Mizukami ◽  
Takaya Tanabe ◽  
Kikuji Katoh ◽  
Takashi Yoshizawa ◽  
...  

2017 ◽  
Vol 5 (23) (3) ◽  
pp. 53-73
Author(s):  
Karolina Kula ◽  
Marcin Markowski

W artykule przedstawiono analizę porównawczą trzech najpopularniejszych rozproszonych systemów plików: Ceph, LizardFS, GlusterFS. Głównym kryterium oceny badanych systemów była ich wydajność, rozumiana jako liczba operacji zapisu i odczytu w jednostce czasu oraz maksymalny transfer danych. Analizę oparto na wynikach licznych eksperymentów przeprowadzonych w opracowanym w tym celu stanowisku badawczym. Część badawczą poprzedzono przeglądem technologii oraz najpopularniejszych istniejących systemów tego typu. W pracy przedstawiono wyniki eksperymentów, ich analizę oraz praktyczne wnioski. In this paper we present a comparative analysis of three most popular distributed file systems: Ceph, LizardFS nad GlusterFS. The main evaluation criterion was the efficiency of systems, meant as the number of read and write operation per second and maximum data transfer rate. The analysis is based on results of many experiments conducted in experimental testbed, prepared for this purpose. Experimental part of the paper is preceded with a survey of technology related to most important distributed file systems. The results of experiments have been presented and analyzed, also some practical conclusions have been formulated.


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