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971.
Do‐Hung Han Jae‐Hyuk Jang Hye‐Young Kim Byung‐Nam Kim Boo‐Young Shin 《Polymer Engineering and Science》2006,46(4):431-437
The high melt viscosity of polypropylene was studied by grafting bifunctional monomers, 1,6‐hexanediol diacrylate (HDDA) and tripropylene glycol diacrylate (TPGDA), onto homopolypropylene (HPP) and random ter‐polypropylene (RTPP) under electron‐beam irradiation. Creation of the high‐melt‐viscosity polypropylene was possible at low radiation dosage and low monomer content, under a prohibition of both radiation degradation and homopolymerization. TPGDA monomer was more effective in increasing the melt viscosity of HPP compared with RTPP, whereas HDDA monomer was more effective for enhancing the melt viscosity of RTPP. Such different effects of monomers on melt viscosity may arise from different monomer structures, namely, TPGDA has additional three methyl groups, but HDDA has no methyl groups. Electron‐beam radiation technology, on an increase of the melt viscosity, was much more effective in HPP than RTPP, when compared with virgin polymers. Modified RTPP and HPP with high melt viscosity were capable of foaming with numerous fine cells, of which the modified HPP with 1.5 mmol TPGDA and 0.5 kGy could create more spherical foam cells and its bending strength was 1.5 times more than that of the foamed RTPP. POLYM. ENG. SCI., 46:431–437, 2006. © 2006 Society of Plastics Engineers. 相似文献
972.
Efective Object Identification and Association by Varying Coverage Through RFID Power Control简
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Shung Han Cho Member EEE Kyung Hoon Kim IEEE Sangjin Hong Senior Member IEEE 《计算机科学技术学报》2014,29(1):4-20
This paper presents an effective power scheduling strategy for energy efficient multiple objects identification and association. The proposed method can be utilized in many heterogeneous surveillance systems with visual sensors and RFID (radio-frequency identification) readers where energy efficiency as well as association rate are critical Multiple objects positions and trajectory estimates are used to decide the power level of RFID readers. Several key parameters including the time windows and the distance separations are defined in the method in order to minimize the effects of RFID coverage uncertainty. The power cost model is defined and incorporated into the method to minimize energy consumption and to maximize association performance. The proposed method computes the power cost using the range of the outermost position for possible single association and group associations at every sampling time. An RFID reader is activated with the proper coverage range when the power cost for the current time is lower than the power cost for the next time sample. The simplicity of the power cost model relieves the problematic combinatorial comparisons in multiple object cases. The performance comparison simulation with the minimum and maximum energy consumption shows that the proposed method achieves fast single associations with less energy consumption. Finally, the realistic comparison simulation with the fixed range RFID readers demonstrates that the proposed method outperforms the fixed ranges in terms of single association rate and energy consumption. 相似文献
973.
Zhi-Ping Jiang Wei Xi Xiangyang Li Shaojie Tang Ji-Zhong Zhao Jin-Song Han Kun Zhao Zhi Wang Bo Xiao 《计算机科学技术学报》2014,29(4):589-604
Numerous indoor localization techniques have been proposed recently to meet the intensive demand for location-based service (LBS). Among them, the most popular solutions are the Wi-Fi fingerprint-based approaches. The core challenge is to lower the cost of fingerprint site-survey. One of the trends is to collect the piecewise data from clients and establish the radio map in crowdsourcing manner. However the low participation rate blocks the practical use. In this work, we propose a passive crowdsourcing channel state information (CSI) based indoor localization scheme, C2IL. Despite a crowdsourcing based approach, our scheme is totally transparent to the client and the only requirement is to connect to our 802.11n access points (APs). C2IL is built upon an innovative method to accurately estimate the moving speed solely based on 802.11n CSI. Knowing the walking speed of a client and its surrounding APs, a graph matching algorithm is employed to extract the received signal strength (RSS) fingerprints and establish the fingerprint map. For localization phase, we design a trajectory clustering based localization algorithm to provide precise real-time indoor localization and tracking. We develop and deploy a practical working system of C2IL in a large office environment. Extensive evaluations indicate that the error of speed estimation is within 3%, and the localization error is within 2 m at 80% time in a very complex indoor environment. 相似文献
974.
975.
Yongwon Seo Sung-Ho Jo Ho-Jung Ryu Hee Dal Bae Chong Kul Ryu Chang-Keun Yi 《Korean Journal of Chemical Engineering》2007,24(3):457-460
A bubbling fluidized bed reactor was used to study CO2 capture from flue gas by using a potassium-based solid sorbent, sorbKX35 which was manufactured by the Korea Electric Power
Research Institute. A dry sorbent, sorbKX35, consists of K2CO3 for absorption and supporters for mechanical strength. To increase initial CO2 removal, some amount of H2O was absorbed in the sorbent before injecting simulated flue gas. It was possible to achieve 100% CO2 removal for more than 10 minutes at 60°C and a residence time of 2 s with H2O pretreatment. When H2O pretreatment time was long enough to convert K2CO3 of sorbKX35 into K2CO3 · 1.5H2O, CO2 removal was excellent. The results obtained in this study can be used as basic data for designing and operating a large scale
CO2 capture process with two fluidized bed reactors.
This work was presented at the 6
th
Korea-China Workshop on Clean Energy Technology held at Busan, Korea, July 4–7, 2006. 相似文献
976.
Buckling of jets in electrospinning 总被引:1,自引:0,他引:1
Various buckling instabilities of electrospinning jets were observed and compared with the buckling instabilities of uncharged fluid jets. Buckling instability arises due to jet compression at impingement on a collector surface and occurs independently of the electrical bending instability. The velocity, diameter, density and viscosity of the electrospinning jets are the key factors that determine the buckling frequency. The electrically charged jets impinging onto grounded, horizontal or inclined (wedge-like) electrodes moving laterally at a constant velocity are studied experimentally. Straight and bending (electrospinning) jets emerge at short and sufficiently long inter-electrode distances, respectively. The experiments show that both straight segment and bending jets, when impinging onto a counter-electrode, buckled and produced patterns of meandering deposits. In the case of bending electrospun jets these short-length buckling patterns were superimposed on the bending loops found in the deposits. Buckling-related and bending-related morphologies are easily distinguishable. The buckling patterns have frequencies of the order of 105-106 Hz, whereas the bending loops are formed at the frequencies of the order of 103 Hz. The deposited buckling patterns include sinuous, zigzag-like, figures-of-eight, recurring curves, coiled and other structures that resembled many patterns created by uncharged jets of highly viscous fluids impinging a hard flat surface. In addition, several new morphologies which were not observed before with uncharged jets were found. The experimentally measured frequencies of the buckling patterns were compared to the theoretical predictions and a reasonable agreement was found. 相似文献
977.
Hongcang Zhou Baosheng Jin Zhaoping Zhong Yaji Huang Rui Xiao Youfei Zheng 《Korean Journal of Chemical Engineering》2007,24(3):489-494
The coal partial gasification catalyzed by limestone, sodium carbonate and dolomite was studied using a bench-scale atmospheric
fluidized bed in the presence of air and steam at 900 °C. The effects of limestone, sodium carbonate and dolomite on composition,
heating value, gas yield of product gas and carbon conversion in the catalytic coal partial gasification have been examined.
The experimental results show that the catalysts can effectively improve the gas quality, the heating value and the gas yield
of product gas and carbon conversion. The catalytic effect of sodium carbonate is better than that of limestone and dolomite.
The increase of limestone loading can enhance the quality of product gas, such as the content of combustible gas, the high
heating value and the gas yield, during coal partial gasification.
This work was presented at the 6
th
Korea-China Workshop on Clean Energy Technology held at Busan, Korea, July 4–7, 2006. 相似文献
978.
979.
Bin Li Chang-Rui Zhang Si-Qing Wang Feng Cao Yong-Gang Jiang 《Refractories and Industrial Ceramics》2007,48(4):280-283
A new wave-transparent composite reinforced by silica fibers with a hybrid matrix comprising BN and Si3N4 was prepared by precursor infiltration and pyrolysis, and it was heat-treated at elevated temperatures. The variations of
the composite during heat treatments were characterized and investigated by Fourier transform infrared spectroscopy (FT-IR),
X-ray diffraction (XRD) and scanning electron microscopy (SEM). The as-received composite exhibits good mechanical properties,
and it is almost amorphous. When treated at 1600°C, it turned brittle, and silica fibers in it were fused; the composite showed
a good crystalline form. When treated at 2100°C, the composite broke into pieces, and the composition showed only BN. Si3N4 was decomposed, and silica fibers were volatilized. The presence of BN probably affected the phase transitions of silica
fibers.
__________
Translated from Novye Ogneupory, No. 8, pp. 49–52, August 2007. 相似文献
980.
Carbon/carbon composites were made through the pyrolysis of stabilized PAN felt and phenolic resin with the addition of 5 or 10 wt % carbon black to the matrix and then heat treatment at 600–2500°C. The effects of adding carbon black to the matrix precursor on the physical properties, microstructure, and mechanical properties of the resultant composites were investigated. Adding carbon black not only reduced the weight loss but also limited the shrinkage of the resultant composites. Adding carbon black also accelerated the formation of carbon basal planes in the matrix. At 2500°C, the crystalline stacking height in the composite with 10 wt % added carbon black was 200% greater than that with no additive. The flexural strength of the composite also increased from 15 to 42 MPa (almost 300%). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 333–337, 2006 相似文献