The cure kinetics of blends of epoxy resin (4,4’-tetraglycidyl diaminodiphenyl methane; TGDDM)/curing agent (diaminodiphenyl
sulfone; DDS) with ATPEI (amine terminated poly-etherimide) -CTBN (carboxyl terminated poly (butadiene-co-acrylonitrile))
block copolymer (AB type) were studied using differential scanning calorimetry under isothermal conditions to determine the
reaction kinetic parameters such as activation energy and reaction constants. Final cure conversion decreased with increasing
amount of AB in the blends. A diffusion controlled reaction was observed as the cure conversion increased, and the curing
reaction was successfully analyzed by incorporating the diffusion control term in the rate equation for the epoxy/DDS/AB blends.
The fracture toughness was improved to about 350% compared to that of the unmodified resin at 30% of AB block copolymer. This
is attributed to the formation of co-continuous morphology between the epoxy phase and AB block copolymer phase. By increasing
the amount of AB, the modulus of the cured blends decreased, which was due to the presence of CTBN rubbery phases. 相似文献
Wireless mesh networks aim to provide high-speed Internet service without costly network infrastructure deployment and maintenance. The main obstacle in achieving high-capacity wireless mesh networks is interference between the mesh links. In this article, we analyze the carrier sensing and interference relations between two wireless links and measure the impact of these relations on link capacity on an indoor 802.11a mesh network testbed. We show that asymmetric carrier sensing and/or interference relations commonly exist in wireless mesh networks, and we study their impact on the link capacity and fair-channel access. In addition, we investigate the effect of traffic rate on link capacity in the presence of interference. 相似文献
Unlike traditional trained channel equalizers, not much work has been done to theoretically characterize the convergence properties of blind channel equalizers due to their inherent nonlinearity. It is only recently that convergence properties of some well-known algorithms such as the generalised Sato algorithm (GSA) and the constant modulus algorithm (CMA) have been analytically derived. In this paper, the convergence properties of the stop-and-go algorithm proposed by Picchi and Prati (1987) are analyzed. The derived mean squared error and the coefficient trajectories are compared with simulation results to verify the validity of the analytical results 相似文献
A vibration aging test is a part of equipment qualification. When the vibration level is too high for the shaker system, the equivalent test can be accomplished by bandsplitting and/or time-level trade techniques. This paper discusses the power spectral density (PSD) band-splitting effect on fatigue damage and a method for the application to PSD bandsplitting. Three types of acceleration PSDs—band-limited white noise (BLWN) PSD, unimodal PSD, and bimodal PSD—with various shapes were chosen as target PSDs. Oritz and Chens method, and Benascuitti and Tovo’s method were used to calculate fatigue damage spectra (FDS). The maximum values of fatigue damage ratios for all target PSDs were calculated. It was found that PSD overlapping can be used to compensate for the lack of fatigue damage due to PSD band-splitting. An application example of the suggested method that enables conservative testing when applying PSD band-splitting is presented herein.
A UV imprint lithography tool has been developed for micro/nano-scale patterning in an extremely large area, i.e., ∼300 × 400 mm2. To achieve high pattern fidelity, residual-layer thickness uniformity, and an air bubble-free layer in a large area, the UV imprint tool has several main components including a silicon rubber uniform pressurizer, a large area UV-LED module, a vacuum pump, a chuck module, etc. Contact and structural analyses have been performed using commercial FEM packages such as LS-DYNA and ANSYS. The developed tool has been tested, and its performance indices including pattern fidelity and residual-layer thickness uniformity have been measured to be ∼97% and ∼90%, respectively. 相似文献
Multimedia Tools and Applications - Congestion-induced delays and pollution in modern transportation systems remain formidable impediments to the sustainable growth of our cities. Next generation... 相似文献