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111.
Fengping Yu Junpo He Xiaojun Wang Guangzheng Gao Yuliang Yang 《Journal of polymer science. Part A, Polymer chemistry》2007,45(17):4013-4025
A combination of nitroxide‐mediated radical polymerization and living anionic polymerization was used to synthesize a series of well‐defined graft (co)polymers with “V‐shaped” and “Y‐shaped” branches. The polymer main chain is a copolymer of styrene and p‐chloromethylstyrene (PS‐co‐PCMS) prepared via nitroxide‐mediated radical polymerization. The V‐shaped branches were prepared through coupling reaction of polystyrene macromonomer, carrying 1,1‐diphenylethylene terminus, with polystyryllithium or polyisoprenyllithium. The Y‐shaped branches were prepared throughfurther polymerization initiated by the V‐shaped anions. The obtained branches, carrying a living anion at the middle (V‐shaped) or at the end of the third segment (Y‐shaped), were coupled in situ with pendent benzyl chloride of PS‐co‐PCMS to form the target graft (co)polymers. The purified graft (co)polymers were analyzed by size exclusion chromatography equipped with a multiangle light scattering detector and a viscometer. The result shows that the viscosities and radii of gyration of the branched polymers are remarkably smaller than those of linear polystyrene. In addition, V‐shaped product adopts a more compact conformation in dilute solution than the Y‐shaped analogy. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4013–4025, 2007 相似文献
112.
A Single-Die 124 dB Stereo Audio Delta-Sigma ADC With 111 dB THD 总被引:1,自引:0,他引:1
This paper presents a highly power-efficient stereo delta-sigma ADC designed for high-precision applications, with measured inter-channel isolation over 130 dB. This design adopts a single-loop, fifth-order, 33 level analog modulator with positive and negative feedforward paths. An interpolated multilevel quantizer with unevenly weighted quantization levels replaces a conventional 5-bit flash type quantizer. These new techniques suppress signal dependent energy inside the delta-sigma loop, reduce internal channel coupling and power consumption. Manufactured in 0.35 mum double poly, three metal CMOS process, the single-die chip includes two analog modulators, on-chip bandgap reference circuit, decimation filter and serial interface circuits. The core die area is around 14.8 mm2. The ADC achieves 124 dB dynamic range (A-weighted), -111 dB THD over 20 kHz bandwidth. Total power consumption is less than 330 mW. 相似文献
113.
Cory J. Hill Baohua Yang Rui Q. Yang 《Physica E: Low-dimensional Systems and Nanostructures》2004,20(3-4):486
Mid-IR type-II interband cascade lasers were demonstrated in pulsed mode at temperatures up to 325 K and in continuous mode up to 200 K. At 80 K, the threshold current density was 8.9 A/cm2 and a continuous wave output power of 140 mW/facet was obtained. 相似文献
114.
The classes ofL
1-matrices,L
2-matrices,L
3-matrices andW-matrices are introduced to study solvability of a linear complementarity problem via solving a linear program. Three sufficient
conditions are presented to guarantee that a linear complementarity problem is solvable via a linear program. The new sufficient
conditions are weaker than the ones introduced by Mangasarian. This fact is also illustrated by an example.
Partially supported by NSFC.
This author is also with College of Business Administration of Human University as a Lotus chair professor. 相似文献
115.
Haihong Fang Binyuan Hu Lingshen Wang Rongli Lu Cui Yang 《Frontiers of Chemistry in China》2008,3(2):193-197
Nanometer MgO was prepared via a sol-gel auto-combustion technique using magnesium nitrate as raw material and citric acid
as chelating agent. IR spectra of the dried gel were used to investigate the structure of the precursors. By studying the
different TG curves of magnesium citrate gel prepared by different methods, we found that a combustion process occurred and
the nitrate ions acted as an oxidant in the combustion process. TEM photographs of synthesized powders from the sol-gel auto-combustion
showed that the crystallites were uniform in size. In addition, the XRD pattern of this sample showed that the particle size
was 8.9 nm. The BET curves, in turn, showed that the specific surface of the sample was 26.34 m2/g. The mechanism of the frothing process in restraining agglomeration is discussed.
__________
Translated from Journal of East China Normal University (Natural Science), 2007, (2): 52–57 [译自: 华东师范大学学报(自然科学版)] 相似文献
116.
Wenping Deng Gang Xu Lei Wan Anwen Liu Bo Gao Junhe Du Shuiming Hu Yang Chen 《Acta Physico》2008,24(8):1329-1334
Apparatus integrating a Fourier transform-infrared (FT-IR) spectrometer and a mid-infrared difference frequency generation (DFG) laser spectrometer was built for the study of the matrix isolation spectrum in solid molecular hydrogen. A 3-cm-long molecular hydrogen crystal was grown in a liquid-helium Dewar, and its infrared absorption spectrum in the 1-5 μm region was recorded to test the system. The W0(0) (ν=0←0, J=6←0) line around 2410 cm−1 of solid hydrogen was investigated with the DFG laser spectroscopy. High-resolution matrix isolation spectrum of CO2 co-deposited with hydrogen on a BaF2 cold plate at liquid-helium temperature was studied. 相似文献
117.
Guey‐Sheng Liou Hung‐Yi Lin Yu‐Lun Hsieh Yi‐Lung Yang 《Journal of polymer science. Part A, Polymer chemistry》2007,45(21):4921-4932
N‐(4‐nitrophenyl)‐4′,4″‐bisformyl‐diphenylamine was synthesized from N‐(4‐nitrophenyl)‐diphenylamine by the Vilsmeier‐Haack reaction. Soluble aromatic poly(azomethine)s (PAMs) were prepared by the solution polycondensation of N‐(4‐nitrophenyl)‐4′,4″‐bisformyl‐diphenylamine and aromatic diamine in N‐methyl‐2‐pyrrolidone (NMP) at room temperature under reduced pressure. All the PAMs are highly soluble in various organic solvents, such as N,N‐dimethylacetamide (DMAc), chloroform (CHCl3), and tetrahydrofuran (THF). Differential scanning calorimetry (DSC) indicated that these PAMs had glass‐transition temperatures (Tgs) in the range of 170–230 °C, and a 10% weight‐loss temperatures in excess of 490 °C with char yield at 800 °C in nitrogen higher than 60%. These PAMs in NMP solution showed UV‐Vis charge‐transfer (CT) absorption at 405–421 nm and photoluminescence peaks around 462–466 nm with fluorescence quantum efficiency (ΦF) 0.10–0.99%. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of these PAMs can be determined from cyclic voltammograms as 4.86–5.43 and 3.31–3.34 eV, respectively. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4921–4932, 2007 相似文献
118.
The mobile agent is a fundamental building block of the mobile computing paradigm. In mobile agent security, oblivious transfer
(OT) from a trusted party can be used to protect the agent’s privacy and the hosts’ privacy. In this paper, we introduce a
new cryptographic primitive called Verifiable Distributed Oblivious Transfer (VDOT), which allows us to replace a single trusted party with a group of threshold trusted servers. The design of VDOT uses a novel
technique called consistency verification of encrypted secret shares. VDOT protects the privacy of both the sender and the receiver against malicious attacks of the servers. We also show the
design of a system to apply VDOT to protect the privacy of mobile agents. Our design partitions an agent into the general
portion and the security-sensitive portion. We also implement the key components of our system. As far as we know, this is
the first effort to implement a system that protects the privacy of mobile agents. Our preliminary evaluation shows that protecting
mobile agents not only is possible, but also can be implemented efficiently.
This work was supported in part by the DoD University Research Initiative (URI) program administered by the Office of Naval
Research under grant N00014-01-1-0795. Sheng Zhong was supported by ONR grant N00014-01-1-0795 and NSF grants ANI-0207399
and CCR-TC-0208972. Yang Richard Yang was supported in part by NSF grant ANI-0207399. A preliminary version of this paper
was presented at the DialM-POMC Joint Workshop on Foundations of Mobile Computing in 2003.
Sheng Zhong received his Ph.D. in computer science from Yale University in the year of 2004. He holds an assistant professor position
at SUNY Buffalo and is currently on leave for postdoctoral research at the Center for Discrete Mathematics and Theoretical
Computer Science (DIMACS). His research interests, on the practical side, are security and incentives in data mining, databases,
and wireless networks. On the theoretical side, he is interested in cryptography and game theory.
Yang Richard Yang is an Assistant Professor of Computer Science at Yale University. His research interests include computer networks, mobile
computing, wireless networking, sensor networks, and network security. He leads the LAboratory of Networked Systems (LANS)
at Yale. His recent awards include a Schlumberger Fellowship and a CAREER Award from the National Science Foundation. He received
his B.E. degree from Tsinghua University (1993), and his M.S. and Ph.D. degrees from the University of Texas at Austin (1998
and 2001). 相似文献
119.
Yang Yu Prasanna V.K. Krishnamachari B. 《Wireless Communications, IEEE Transactions on》2006,5(11):3087-3096
This paper studies the challenging problem of energy minimization for data gathering over a multiple-sources single-sink communication substrate in wireless sensor networks by exploring the energy-latency tradeoffs using rate adaptation techniques. We consider a real-time scenario for mission-critical applications, where the data gathering must be performed within a specified latency constraint. We first propose an offline numerical optimization algorithm with performance analysis for a special case with a complete binary data gathering tree. Then, by discretizing the transmission time, we present a simple, distributed on-line protocol that relies only on the local information available at each sensor node. Extensive simulations were conducted for both long and short-range communication scenarios using two different source placement models. We used the baseline of transmitting all packets at the highest speed and shutting down the radios afterwards. Our simulation results show that compared with this baseline, up to 90% energy savings can be achieved by our techniques (both off-line and on-line), under different settings of several key system parameters 相似文献
120.
文章报道了空间多光谱扫描仪红外波段多元光导碲镉汞探测器的研制与优值。重点研究并解决了多元器件光谱曲线不一致性的问题,简述了器件的优值波段响应率RΔλ1,波段探测率DΔλ和单色响应率Rλ的测试定标方法,以及器件按空间环境使用要求经历老炼和环境条件试验的情况。测试结果表明多元件性能稳定可靠,各项指标均达到了空间多光谱扫描仪的技术要求。 相似文献