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51.
A high-speed and error-free voiceband data communication method using a hybrid automatic repeat request (ARQ) protocol over an analog cellular system is described. The present method adopts an adaptive error control scheme. This error control scheme automatically selects the optimal error correction code according to circuit bit error rate (BER), so as to match it to the frequently changing mobile radio propagation path conditions. This method adopts multiframe rejection as a retransmission scheme for a high throughput efficiency on the burst error circuit. Actual field evaluation was made by mounting this protocol on a CCITT V.22 bis modem with a data transmission speed of 2400 b/s and a modulation method using 16 carrier states over the Advanced Mobile Phone Service (AMPS) in Atlanta, GA, verifying that data communications can be achieved with an average throughput efficiency of 70% over a radio channel having a BER up to 10-2 相似文献
52.
Evidence that Crystal Facet Orientation Dictates Oxygen Evolution Intermediates on Rutile Manganese Oxide 下载免费PDF全文
Hirotaka Kakizaki Hideshi Ooka Toru Hayashi Nadège Bonnet‐Mercier Kazuhito Hashimoto Ryuhei Nakamura 《Advanced functional materials》2018,28(24)
Elucidating the mechanism that differentiates the oxygen‐evolving center of photosystem II with its inorganic counterpart is crucial to develop efficient catalysts for the oxygen evolution reaction (OER). Previous studies have suggested that the larger overpotential for MnO2 catalysts under neutral conditions may result from the instability of the Mn3+ intermediate to charge disproportionation. Here, by monitoring the surface intermediates of electrochemical OER on rutile MnO2 with different facet orientations, a correlation between the stability of the intermediate species and crystal facets is confirmed explicitly for the first time. The coverage of the Mn3+ intermediate is found to be 11‐fold higher on the metastable (101) surfaces compared to (110) surfaces, leading to the superior OER activity of (101) surfaces. The difference in OER activity may result from the difference in surface electronic states of Mn3+, where interlayer charge comproportionation of Mn2+ and Mn4+ to generate two Mn3+ species is favored on (101) facets. Considering the fact that the OER enzyme accommodates Mn3+ stably during the Kok cycle, the enhanced OER activity of the rutile MnO2 catalyst with a metastable surface highlights the importance of mimicking not only the crystal structure but also the electronic structure of the targeted natural enzyme. 相似文献
53.
Qingwei Yan Fakhr E. Alam Jingyao Gao Wen Dai Xue Tan Le Lv Junjie Wang Huan Zhang Ding Chen Kazuhito Nishimura Liping Wang Jinhong Yu Jibao Lu Rong Sun Rong Xiang Shigeo Maruyama Hang Zhang Sudong Wu Nan Jiang Cheng-Te Lin 《Advanced functional materials》2021,31(36):2104062
Urged by the increasing power and packing densities of integrated circuits and electronic devices, efficient dissipation of excess heat from hot spot to heat sink through thermal interface materials (TIMs) is a growing demand to maintain system reliability and performance. In recent years, graphene-based TIMs received considerable interest due to the ultrahigh intrinsic thermal conductivity of graphene. However, the cooling efficiency of such TIMs is still limited by some technical difficulties, such as production-induced defects of graphene, poor alignment of graphene in the matrix, and strong phonon scattering at graphene/graphene or graphene/matrix interfaces. In this study, a 120 µ m-thick freestanding film composed of vertically aligned, covalently bonded graphene nanowalls (GNWs) is grown by mesoplasma chemical vapor deposition. After filling GNWs with silicone, the fabricated adhesive TIMs exhibit a high through-plane thermal conductivity of 20.4 W m−1 K−1 at a low graphene loading of 5.6 wt%. In the TIM performance test, the cooling efficiency of GNW-based TIMs is ≈ 1.5 times higher than that of state-of-the-art commercial TIMs. The TIMs achieve the desired balance between high through-plane thermal conductivity and small bond line thickness, providing superior cooling performance for suppressing the degradation of luminous properties of high-power light-emitting diode chips. 相似文献
54.
55.
The mechanism of the self-assembly of the lamellar structure of natural stratum corneum lipids (SCL) has been a subject of
considerable interest. We have examined this question by using a synthetic pseudo-ceramide (sphingolipid E, SLE) which was
analogous to the naturally occurring ceramide type 2. The thermotropic properties and the structural characteristics of SLE,
together with other main components of SCL, fatty acids, and cholesterol, were investigated by differential scanning calorimetry
and X-ray analysis. A mixture of SLE and stearic acid was in a stable α-form having a lamellar structure, which is very similar
to that of natural SCL. However, lipid mixtures in which stearic acid were replaced by oleic acid did not form lamellar structures,
and existed in the crystalline states. This indicates that the stable bilayer formation of the natural SCL is strongly dependent
on the molecular fatty acid structure. Moreover, incorporation of cholesterol (0–50%) into equimolar mixtures of SLE/stearic
acid and of SLE/oleic acid caused a marked decrease of melting entropies, while the aggregation states of both systems were
not changed. This effect of cholesterol can be attributed to the disorder of the molecular packing. These results suggest
that the hydrophobic interactions between the SCL are important for bilayer formation as are the hydrophilic interactions
between the polar groups. 相似文献
56.
Yoshiyuki Sato Ming Wang Shigeki Takishima Hirokatsu Masuoka Taku Watanabe Yoshihito Fukasawa 《Polymer Engineering and Science》2004,44(11):2083-2089
The solubility of butane and isobutane in molten polypropylene (PP) and polystyrene (PS) was measured at pressures up to 3 MPa and along four isotherms from 438 to 483 K for PP and from 348 to 473 K for PS. The solubility increased with increasing pressure and decreasing temperature. At 438 K and 2 MPa, the solubilities of butane and isobutane in PP were 0.15 and 0.11 g‐gas/g‐polym, respectively. At 423 K and 2 MPa, the solubilities of butane and isobutane in PS were 0.08 and 0.05 g‐gas/g‐polym, respectively. Solubility could be correlated with the Sanchez‐Lacombe equation of state with temperature‐dependent binary interaction parameters to within 4.4% average relative deviation. Henry's constant for these gases in the PP and PS obtained in this work were used to determine correlation equations along with literature data. Polym. Eng. Sci. 44:2083–2089, 2004. © 2004 Society of Plastics Engineers. 相似文献
57.
Summary Diaphorase is immobilized on electrodes derived from metal-plated polyester cloth by entrapment method and coupled with an
electron mediator. Cyclic voltammogram depended on the existence of the substrate NADH (for oxidation) or NAD+ (for reduction) and the flavo-enzyme was shown to exchange electron(s) with the cloth electrode by mediation of the ferrocene
derivative (for oxidation cycle) or the viologen derivative (for reduction cycle), even in the immobilized state. Coupling
of the NADH or NAD+ regenerating system with alcohol dehydrogenase was examined. 相似文献
58.
Takahiro Sasai Nobuko Saigusa Akihiko Ito Ramakrishna Nemani Kazuhito Ichii Taku M. Saitoh Kazutaka Murakami Takehisa Oikawa 《Remote sensing of environment》2011,115(7):1758-1771
The terrestrial carbon cycle is strongly affected by natural phenomena, terrain heterogeneity, and human-induced activities that alter carbon exchange via vegetation and soil activities. In order to accurately understand terrestrial carbon cycle mechanisms, it is necessary to estimate spatial and temporal variations in carbon flux and storage using process-based models with the highest possible resolution. We estimated terrestrial carbon fluxes using a biosphere model integrating eco-physiological and mechanistic approaches based on satellite data (BEAMS) and observations with 1-km grid resolution. The study area is the central Far East Asia region, which lies between 30° and 50° north latitude and 125° and 150° east longitude. Aiming to simulate terrestrial carbon exchanges under realistic land surface conditions, we used as many satellite-observation datasets as possible, such as the standard MODIS, TRMM, and SRTM high-level land products. Validated using gross primary productivity (GPP), net ecosystem production (NEP), net radiation and latent heat with ground measurements at six flux sites, the model estimations showed reasonable seasonal and annual patterns. In extensive analysis, the total GPP and NPP were determined to be 2.1 and 0.9 PgC/year, respectively. The total NEP estimation was + 5.6 TgC/year, meaning that the land area played a role as a carbon sink from 2001 to 2006. In analyses of areas with complicated topography, the 1-km grid estimation could prove to be effective in evaluating the effect of landscape on the terrestrial carbon cycle. The method presented here is an appropriate approach for gaining a better understanding of terrestrial carbon exchange, both spatially and temporally. 相似文献
59.
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