scholarly journals Development of Heat Dissipation Multilayer Media for Volumetric Magnetic Hologram Memory

2019 ◽  
Vol 9 (9) ◽  
pp. 1738 ◽  
Author(s):  
Nakamura ◽  
Lim ◽  
Goto ◽  
Uchida ◽  
Inoue
Keyword(s):  
Diffraction Efficiency ◽  
Heat Dissipation ◽  
Data Transfer ◽  
Single Layer ◽  
Heat Diffusion ◽  
Holographic Memory ◽  
Recording Process ◽  
Layer Medium ◽  
Strong Candidate ◽  
Multilayer Media

Holographic memory is a strong candidate for next-generation optical storage, featuring high recording densities and data transfer rates, and magnetic hologram memory using a magnetic garnet, as the recording material is expected to be used as a rewritable and stable storage technology. However, the diffraction efficiency of magnetic holography depending on the Faraday rotation angle is insufficiently high for actual storage devices. To increase the diffraction efficiency, it is important to record deep magnetic fringes, whereas it is necessary to suppress the merging of fringes owing to heat diffusion near the medium surface. In this work, we investigated the recording process of magnetic holograms in detail with experiments and numerical simulations, and developed a multilayer media with transparent heat dissipation layers to record deep and clear magnetic holograms by controlling the heat diffusion generated during the thermomagnetic recording process. To suppress lateral heat diffusion near the medium surface, we designed and fabricated a multilayer magnetic medium in which the recording magnetic layers are discrete in a film, approximately 12-µm thick. This medium exhibited diffraction efficiency higher than that of the single-layer medium, and error-free recording and reconstruction were achieved using the magnetic assist technique.

scholarly journals Magnetic Holography and Its Application to Data Storage

Photonics ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 187
Author(s):  
Yuichi Nakamura
Keyword(s):  
Data Storage ◽  
Heat Dissipation ◽  
Single Layer ◽  
Holographic Memory ◽  
Magnetization Direction ◽  
Reconstruction Image ◽  
Potential Applications ◽  
Magneto Optical Effect ◽  
Layer Medium ◽  
Recording Conditions

The principle of magnetic holograms and its application to holographic memory are reviewed. A magnetic hologram was recorded through a thermomagnetic recording as a difference in magnetization direction and reconstructed with the magneto-optical effect. To achieve a bright reconstruction image, it is important to record deep magnetic fringes on the materials with large Faraday rotation coefficients. This technique was applied to the holographic memory using transparent magnetic garnets as a recording material. The first reconstruction image was dark and noisy, but improvements in the recording conditions resulted in error-free recording and reconstruction of the magnetic hologram. To form deep magnetic fringes, insertion of heat dissipation (HD) layers into recording layer was proposed. It was found that this HD multilayer medium showed diffraction efficiency higher than that of a single layer medium, and error-free recording and reconstruction were also achieved, using magnetic assisted recording. These results suggest that HD multilayer media have potential applications in recording media of magnetic holographic data storage. In future, a high recording density technique, such as multiple recording, should be developed.

Effects of Varying Geometrical Parameters on Boiling From Microfabricated Enhanced Structures

2003 ◽  
Vol 125 (1) ◽  
pp. 103-109 ◽  
Author(s):  
C. Ramaswamy ◽  
Y. Joshi ◽  
W. Nakayama ◽  
W. B. Johnson
Keyword(s):  
Heat Dissipation ◽  
Layer Structure ◽  
Single Layer ◽  
Nucleate Boiling ◽  
Heat Fluxes ◽  
Working Fluid ◽  
Geometrical Parameters ◽  
Small Range ◽  
Two Phase ◽  
Wall Superheat

The current study involves two-phase cooling from enhanced structures whose dimensions have been changed systematically using microfabrication techniques. The aim is to optimize the dimensions to maximize the heat transfer. The enhanced structure used in this study consists of a stacked network of interconnecting channels making it highly porous. The effect of varying the pore size, pitch and height on the boiling performance was studied, with fluorocarbon FC-72 as the working fluid. While most of the previous studies on the mechanism of enhanced nucleate boiling have focused on a small range of wall superheats (0–4 K), the present study covers a wider range (as high as 30 K). A larger pore and smaller pitch resulted in higher heat dissipation at all heat fluxes. The effect of stacking multiple layers showed a proportional increase in heat dissipation (with additional layers) in a certain range of wall superheat values only. In the wall superheat range 8–13 K, no appreciable difference was observed between a single layer structure and a three layer structure. A fin effect combined with change in the boiling phenomenon within the sub-surface layers is proposed to explain this effect.

Manufacture of thin rice straw particleboards bonded with various polymeric methane diphenyl diisocyanate/ urea formaldehyde resin mixtures

BioResources ◽  
2019 ◽  
Vol 15 (1) ◽  
pp. 935-944
Author(s):  
Peng Luo ◽  
Chuanmin Yang ◽  
Mengyao Li ◽  
Yueqi Wang
Keyword(s):  
Mechanical Properties ◽  
Rice Straw ◽  
Water Resistance ◽  
Urea Formaldehyde ◽  
Single Layer ◽  
Formaldehyde Resin ◽  
Manufacturing Cost ◽  
Board Density ◽  
Layer Medium ◽  
Resin Formulation

Reducing particleboard thickness is one of the major approaches to decrease consumption volume of particleboard for furniture manufacture. This study employed an adhesive mixture of polymeric methane diphenyl diisocyanate (PMDI) and urea formaldehyde (UF) to produce single-layer medium density thin rice straw particleboard. The effects of various PMDI/UF formulations as well as board density on mechanical properties and water resistance of rice straw particleboard were studied. The results indicated that the mechanical properties and water resistance of the thin rice straw particleboard were appreciably affected by resin formulation. The panels bonded with PMDI/UF adhesive mixtures had mechanical properties and water resistance far superior to those bonded with UF. Higher PMDI content levels in resin mixtures led to improved mechanical properties and water resistance. Density influenced mechanical properties and water resistance of the thin rice straw particleboard. Increasing the density of the panel could upgrade the mechanical properties of the thin rice straw particleboard. The experimental outcomes showed that PMDI/UF resin systems had potential to substitute for pure PMDI resin in producing thin rice straw particleboard, which could effectively lower manufacturing cost and bring economic efficiencies due to reduced amount of pricey PMDI.

scholarly journals Development of Thermally Conductive Polyurethane Composite by Low Filler Loading of Spherical BN/PMMA Composite Powder

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Kai-Han Su ◽  
Cherng-Yuh Su ◽  
Cheng-Ta Cho ◽  
Chung-Hsuan Lin ◽  
Guan-Fu Jhou ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Heat Dissipation ◽  
Three Dimensional ◽  
Filler Loading ◽  
High Thermal Conductivity ◽  
Heat Diffusion ◽  
Composite Powders ◽  
Polyurethane Composite ◽  
Uniform Dispersion ◽  
Thermally Conductive

Abstract The issue of electronic heat dissipation has received much attention in recent times and has become one of the key factors in electronic components such as circuit boards. Therefore, designing of materials with good thermal conductivity is vital. In this work, a thermally conductive SBP/PU composite was prepared wherein the spherical h-BN@PMMA (SBP) composite powders were dispersed in the polyurethane (PU) matrix. The thermal conductivity of SBP was found to be significantly higher than that of the pure h-BN/PU composite at the same h-BN filler loading. The SBP/PU composite can reach a high thermal conductivity of 7.3 Wm−1 K−1 which is twice as high as that of pure h-BN/PU composite without surface treatment in the same condition. This enhancement in the property can be attributed to the uniform dispersion of SBP in the PU polymer matrix that leads to a three-dimensional continuous heat conduction thereby improving the heat diffusion of the entire composite. Hence, we provide a valuable method for preparing a 3-dimensional heat flow path in polyurethane composite, leading to a high thermal conductivity with a small amount of filler.

scholarly journals Theoretical Study of a Surface Collinear Holographic Memory

Photonics ◽  
2019 ◽  
Vol 6 (2) ◽  
pp. 70
Author(s):  
Hirayama ◽  
Fujimura ◽  
Umegaki ◽  
Tanaka ◽  
Shimura
Keyword(s):  
Data Storage ◽  
Transfer Rate ◽  
Data Transfer ◽  
Coefficient Of Thermal Expansion ◽  
Storage System ◽  
Reconstructed Image ◽  
Data Transfer Rate ◽  
Holographic Memory ◽  
High Data ◽  
Volume Holograms

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.

scholarly journals Some advantages of three-layer medium-density fibreboard as compared to the traditional single-layer one

2019 ◽  
Vol 65 (1) ◽  
Author(s):  
Turgay Akbulut ◽  
Nadir Ayrilmis
Keyword(s):  
Bond Strength ◽  
Internal Bond ◽  
Single Layer ◽  
Middle Layer ◽  
Resin Content ◽  
Internal Bond Strength ◽  
Medium Density ◽  
Medium Density Fibreboard ◽  
Uf Resin ◽  
Layer Medium

Abstract The aim of the study was to develop three-layer medium-density fibreboard (MDF) manufacture by adding the coarse fibres in the middle layer, like three-layer particleboard. The liquid urea–formaldehyde (UF) resin was reduced from 10.5 to 6.5 wt% in the middle layer of the MDFs. The UF resin content was kept constant at 10 wt% in the surface layers of all the MDFs. Moreover, the average density of MDFs was decreased from 730 to 650 kg/m3. The internal bond strength of three-layer MDFs decreased with decreasing UF resin content (10.5 to 8.5 wt%) in the middle layer. However, the decreases in the internal bond strength were statistically not significant. The internal bond strength values of the MDFs having density between 730 and 675 kg/m3 did not show significant differences. The cost savings of the resin were 20% when the amount of resin was reduced from 10.5 to 8.5 wt%. Three-layer MDFs had lower resin consumption at lower densities over traditional single-layer MDFs produced in the same plant with the same material components without decreasing their technological properties. In conclusion, it can be said that three-layer MDF could be produced at a lower cost than traditional single-layer MDF.

scholarly journals Graphene two terminal detector as THz mixer

2021 ◽  
Vol 2086 (1) ◽  
pp. 012054
Author(s):  
A Sh Gazaliev ◽  
M V Moskotin ◽  
V V Belosevich ◽  
M G Rybin ◽  
I A Gayduchenko ◽  
...  
Keyword(s):  
Communication Networks ◽  
Data Transfer ◽  
Single Layer ◽  
Heterodyne Detection ◽  
Single Layer Graphene ◽  
Thz Radiation ◽  
Transfer Rates ◽  
Bowtie Antenna ◽  
Radiation Sources ◽  
Maximum Transmission

Abstract The growing requirements for mobile communication networks (data transfer rates over 100 Gbps) makes it necessary to use carrier signal with a frequency of at least 100 GHz. This requires the development of cheap and broadband sub-terahertz (sub-THz) detectors. Here we report on our recent efforts toward the development of a heterodyne sub-THz detector based on a single layer graphene two-terminal device integrated with a bowtie antenna on a sapphire substrate. Our detector operates at frequency of 140 GHz, which corresponds to the maximum transmission of THz radiation in the Earth’s atmosphere. The heterodyne detection is achieved by quasi-optical coupling of signals from two sub-THz radiation sources to the same detector. The measured frequency bandwidth is 5.8 GHz.

scholarly journals Влияние побочных дифракционных порядков на качество изображения, формируемого рефракционно-дифракционной оптической системой среднего ИК диапазона

2021 ◽  
Vol 129 (4) ◽  
pp. 378
Author(s):  
Г.И. Грейсух ◽  
Е.Г. Ежов ◽  
О.А. Захаров ◽  
С.В. Казин
Keyword(s):  
Computer Simulation ◽  
Image Quality ◽  
Diffraction Efficiency ◽  
Spectral Range ◽  
Optical System ◽  
Optical Axis ◽  
Single Layer ◽  
Central Wavelength ◽  
Relief Phase

The image formed by a refractive-diffractive optical system for the mid-IR range (3–5 µm) is investigated. The effect of the side diffraction orders of the diffractive corrector on the quality of this image near the optical axis is estimated both by computer simulation and experimentally. It is shown that the side diffraction orders of a single-layer sawtooth relief-phase microstructure will not noticeably affect the image quality under the following condition: the diffraction efficiency of the microstructure at the central wavelength of the operating spectral range is close to unity, and within the entire indicated spectral range it does not drop below 0.67.

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