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61.
Charles E. Baumgartner 《Journal of the American Ceramic Society》1990,73(3):516-520
The performance of a molten carbonate fuel cell (MCFC) is significantly eroded when fuel and oxidant gases are allowed to combine chemically as occurs with a loss of gas impermeability by the cell's electrolyte structure. This performance decline is eradicated when the cell's electrodes possess pore size distributions small enough to absorb sufficient electrolyte to act as a secondary gas barrier. Described here is a process for preparing composite MCFC NiO cathodes where the median pore size of the gas barrier region is varied from 3.2 to 0.4 μm by adjusting the starting powder's Ni/NiO ratio. When filled with liquid Li2 CO3 -38 mol% K2 CO3 at 923 K, these structures possess a gas pressure resistance of between 2.3 × 105 and 13.6 × 105 Pa, respectively. The incorporation of these composite cathodes in a MCFC can prevent the penetration of the oxidant gas into the fuel cell's interior. 相似文献
62.
Charles L. Rohn 《乙烯基与添加剂工艺杂志》1990,12(2):95-98
PVC is one of the most versatile and cost effective commercial polymers. A main limitation of PVC is optimizing its fabrication characteristics and end use properties with minimum adverse effect on either. PVC compounding technology is supersensitive due to effect of subtle variations in formulations causing “inspec” products during one production run and “out-of-spec” products in another. Large variations in properties are frequently due to improper mixing. Dynamic mechanical analyses provides a method of monitoring variations in mixing and their affect on morphological structure deviations which can lead to poor processing and end use properties. 相似文献
63.
Garrocho Charles T. B. da Silva Maurício J. Oliveira Ricardo A. R. 《Wireless Networks》2020,26(1):373-386
Wireless Networks - D2D (device-to-device) communication is one of the developments of 5G networks (5th generation mobile networks) that reduce mobile traffic load, reduce energy consumption and... 相似文献
64.
Matthew J. La Pan T. Charles Clancy Robert W. McGwier 《Wireless Communications and Mobile Computing》2016,16(2):177-191
Orthogonal frequency‐division multiplexing (OFDM) has become the manifest modulation choice for 4G standards. Timing acquisition and carrier frequency offset synchronization are prerequisite to OFDM demodulation and must be performed often. Most of the OFDM methods for synchronization were not designed with security in mind. In particular, we analyze the performance of a maximum likelihood synchronization estimator against highly correlated jamming attacks. We present a series of attacks against OFDM timing acquisition: preamble whitening, the false preamble attack, preamble warping, and preamble nulling.The performance of OFDM synchronization turns out to be very poor against these attacks, and a number of mitigation strategies and security improvements are discussed. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
65.
N. Carr J. Thompson G. G. Jones I. Griffith A. J. Moseley P. M. Charles 《Journal of Electronic Materials》1995,24(11):1617-1620
The use of optoelectronic integrated circuits (OEICs) is now emerging as a practical technology for a variety of applications, particularly in advanced telecommunications. OEICs consist of a range of devices such as lasers, waveguides, modulators, amplifiers, transistors, detectors, etc. fabricated on the same substrate. When a semi-insulating substrate is used, these devices can be electrically isolated by channel etching, resulting in a low capacitance structure with reduced electrical interference between the subcomponents. One of the devices which is particularly advantageous for this type of integration scheme is the distributed feedback (DFB) laser. The laser can be made to function more efficiently by minimizing the current flowing outside the active region. This can be achieved by surrounding the active region with semi-insulating iron doped InP. This work describes for the first time, the MOVPE growth, fabrication, and device characterization of 1.3 um buried heterostructure DFB MQW lasers, which combine the advantages of using both a semi-insulating substrate and a semi-insulating infill region in the same device structure. The potential advantage of this design scheme is improved OEIC performance as a result of, reduced capacitance and electrical crosstalk, enhanced laser output power, higher speed, increased efficiency, wider operating temperature and reduced threshold current. The laser active region consists of 8 x 140 Å quantum wells of GalnAsP (λ = 1.3 μm) and 110 Åbarriers of GalnAsP (λ= 1.07 μm). Single mode 1.3 urn devices of length 250 μm operating at room temperature produced threshold currents of 8 mA, efficiencies of up to 25%, output powers of 18 mW at 80 mA (pulsed), and a frequency response greater than 12GHz. The parasitic capacitance was estimated to be less than 3 pF. 相似文献
66.
In this paper, an experimental mixed reality using a multimodal approach is introduced which lets users play characters in interactive narratives as though acting on a stage. Users interact with characters through speech, attitude, and gesture, enhancing their immersion in the virtual world. This system provides a small-scale but complete integration of multimodal communication in interactive storytelling. It uses a narrative's semantic context to focus multimodal input processing-that is, the system interprets users' acting (the multimodal input) in the mixed reality stage in terms of narrative functions representing users' contributions to the unfolding plot. 相似文献
67.
Williams P.J. Walker R.G. Charles P.M. Ogden R. Wood A.K. Carr N. Carter A.C. 《Electronics letters》1991,27(10):809-810
The fabrication and characterisation of monolithically integrated OEIC transceivers for use in optical subscriber access links are reported. A design incorporating DFB lasers, wavelength duplexers and a monitor photodiode, specific to the TPON/BPON passive optical network configuration is presented.<> 相似文献
68.
Charles H. Woloszynski 《International Journal of Communication Systems》1991,4(2):109-115
This paper examines the current work within various standards bodies to define a multi-configuration medium access control (MAC) protocol for operation between broadband ISDN terminals. To begin, the configurations in which the MAC protocol is expected to operate are introduced. The relation between the MAC protocol and the broadband ISDN resource allocation schemes is then discussed. Several MAC protocol proposals currently being discussed in various standards bodies, each with unique assumptions regarding resource allocation in broadband ISDN, are then described and compared. Finally, areas for future work on this topic are identified. 相似文献
69.
Pitts Danid E. Badhwar Gautam D. Thompson David R. Henderson Keith E. Shen S. Sylvia Sorensen Charles T. Carnes Jess G. 《Geoscience and Remote Sensing, IEEE Transactions on》1984,(3):312-318
Multitemporal Thematic Mapper, Thematic Mapper Simulator, and detailed ground truth data were collected for a 9-by 1-km sample segment in Webster County, Iowa, in the summer of 1982. Three dates were acquired each with Thematic Mapper Simulator (June 7, June 23, and July 31) and Thematic Mapper (August 2, September 3, and October 21). The Thematic Mapper Simulator data were converted to equivalent TM count values using TM and TMS calibration data and model based estimates of atmospheric effects. The July 31, TMS image was compared to the August 2, TM image to verify the conversion process. A quantitative measure of proportion estimation variance (Fisher information) was used to evaluate the corn/soybeans separability for each TM band as a function of time during the growing season. The additional bands in the middle infrared allowed corn and soybeans to be separated much earlier than was possible with the visible and near-infrared bands alone. Using the TM and TMS data, temporal profiles of the TM principal components were developed. The greenness and brightness exhibited behavior similar to MSS greenness and brightness for corn and soybeans. 相似文献
70.
For 32/22 nm technology nodes and below, double patterning (DP) lithography has become the most promising interim solutions due to the delay in the deployment of next generation lithography (e.g., EUV). DP requires the partitioning of the layout patterns into two different masks, a procedure called layout decomposition. Layout decomposition is a key computational step that is necessary for double patterning technology. Existing works on layout decomposition are all single-threaded, which is not scalable in runtime and/or memory for large industrial layouts. This paper presents the first window-based parallel layout decomposition methods for improving both runtime and memory consumption. Experimental results are promising and show the presented parallel layout decomposition methods obtain upto 21× speedup in runtime and upto 7.5×reduction in peak memory consumption with acceptable solution quality. 相似文献