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351.
Chih‐Ping Chen Shenghong A. Dai Huey‐Ling Chang Wen‐Chiung Su Ru‐Jong Jeng 《Journal of polymer science. Part A, Polymer chemistry》2005,43(3):682-688
A bifunctional compound [(4‐isocyanato‐4′(3,3‐dimethyl ‐2,4‐dioxo‐acetidino)diphenylmethane] (MIA) has been used as a building block for the synthesis of novel polyurea/malonamide dendrons. This is based on selectively sequential addition reactions of amines to isocyanato‐azetidine‐2,4‐diones. After incorporation of the MIA onto the growing dendrons, rapid entry into polyurea/malonamide dendrons was achieved via a convergent route with the processing advantages of easy purification, high yield, and rapid synthesis. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 682–688, 2005 相似文献
352.
Keh-Yi Lee Chun-Hsien Lee Cheng-Hsun Tsai Min-Hsueh Jiang Jee-Fu Shueh Jian-Han Lai Yo-Long Jeng Yi-Shin Chao 《Optical and Quantum Electronics》2009,41(2):91-98
In this paper, we utilize the finite-difference time-domain method to analyze the transmission characteristics of the point-defected
periodical dielectric waveguides (point-defected PDWGs). Each point-defected PDWG contains a defected cylinder distinct from
the others. It is found that the optical transmittance becomes worse due to the shorter defected cylinder but it is not affected
by the longer one. Moreover, the optical transmission is very sensitive to the radius of the defected cylinder whatever it
is larger or smaller than that of the other cylinders. 相似文献
353.
The central problem in the implementation of a Reed-Solomon code is finding the roots of the error locator polynomial. In 1967, Berlekamp et al. found an algorithm for finding the roots of an affine polynomial in GF(2m) that can be used to solve this problem. In this paper, it is shown that this Berlekamp-Rumsey-Solomon (1967) algorithm, together with the Chien (1964) search method, makes possible a fast decoding algorithm in the standard-basis representation that is naturally suitable in a software implementation. Finally, simulation results for this fast algorithm are given 相似文献
354.
Ling Wu Jie Zheng Liang Wang Xunhui Xiong Yanyan Shao Gang Wang Jeng‐Han Wang Shengkui Zhong Minghong Wu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(3):821-825
Nanostructured‐alloy‐type anodes have received great interest for high‐performance lithium‐ion batteries (LIBs). However, these anodes experience huge volume fluctuations during repeated lithiation/delithiation and are easily pulverized and subsequently form aggregates. Herein, an efficient method to stabilize alloy‐type anodes by creating defects on the surface of the metal oxide support is proposed. As a demonstration, PPy‐encapsulated SnS2 nanosheets supported on defect‐rich TiO2 nanotubes were produced and investigated as an anode material for LIBs. Both experimental results and theoretical calculations demonstrate that defect‐rich TiO2 provides more chemical adhesions to SnS2 and discharge products, compared to defect‐poor TiO2, and then effectively stabilizes the electrode structure. As a result, the composite exhibits an unprecedented cycle stability. This work paves the way to designing durable and active nanostructured‐alloy‐type anodes on oxide supports. 相似文献
355.
We report on the theoretical derivation and experimental observation of spatiotemporal modulation instability (MI) of a coherent light beam in noninstantaneous nonlinear media. We obtain analytically the MI growth rate as a function of the spatial and temporal frequencies of the perturbation and the material response time. In the experiment, we observe that the varying speed of the MI patterns increases with the decreased material response time. We also observe that increasing the material response time can arrest the MI, agreeing with our theoretical derivation. 相似文献
356.
The resonance energies for attachment of an electron to the chloromethanes and the ionization potentials of the chloromethanes were studied both by the multiple scattering Xα-SCF method and by the PM3 method. An external positively charged Watson sphere is used to stabilize the resonances in the Xα method. The calculated results provide support for the assignment of the features observed in the electron transmission spectra of the chloromethanes. 相似文献
357.
This paper considers a single-machine scheduling problem of minimizing the maximum completion time for a set of independent jobs. The processing time of a job is a non-linear step function of its starting time and due date. The problem is already known to be ????-hard in the literature. In this paper, we first show this problem to be ????-hard in the ordinary sense by proposing a pseudo-polynomial time dynamic programming algorithm. Then, we develop two dominance rules and a lower bound to design a branch-and-bound algorithm for deriving optimal solutions. Numerical results indicate that the proposed properties can effectively reduce the time required for exploring the solution space. 相似文献
358.
We observe stable propagation of spatially localized single- and double-charge optical vortices in a self-focusing nonlinear medium. The vortices are created by self-trapping of partially incoherent light carrying a phase dislocation, and they are stabilized when the spatial incoherence of light exceeds a certain threshold. We confirm the vortex stabilization effect by numerical simulations and also show that the similar mechanism of stabilization applies to higher-order vortices. 相似文献
359.
We demonstrate theoretically and experimentally that induced spatiotemporal modulation instability can exist in a self-defocusing medium if the nonlinearity is noninstantaneous. We predict the growth rate as a function of the spatial and temporal frequencies of the modulation and the response time of the nonlinearity and confirm it by our experiments. 相似文献
360.
Shin-Hon Chen Shyh-Kang Jeng 《Vehicular Technology, IEEE Transactions on》1996,45(3):570-578
We propose a deterministic approach to model the radio propagation channels in tunnels with and without traffic. This technique applies the modified shooting and bouncing ray (SBR) method to find equivalent sources (images) in each launched ray tube and sums the receiving complex amplitude contributed by all images coherently. In addition, the vector effective antenna height (VEH) is introduced to consider the polarization-coupling effect resulting from the shape of the tunnels. We verify this approach by comparing the numerical results in two canonical examples where closed-form solutions exist. The good agreement indicates that our method can provide a good approximation of high-frequency radio propagation inside tunnels where reflection is dominant. We show that the propagation loss in tunnels can vary considerably according to the tunnel shapes and the traffic inside them. From the results we also find a “focusing” effect, which makes the power received in an arched tunnel higher than that in a rectangular tunnel. Besides, the deep fading that appears in a rectangular tunnel is absent in an arched tunnel. The major effect of the traffic is observed to be the fast fading due to the reflection/obstruction of vehicles. Additional considerations, such as time delay, wall roughness, and wedge diffraction of radio wave propagation in tunnels are left for future studies 相似文献