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排序方式: 共有563条查询结果,搜索用时 15 毫秒
1.
Julio E. Trevino Swati Mohan Alexandra E. Salinas Emilia Cueva Karen Lozano 《应用聚合物科学杂志》2021,138(28):50665
This study presents the development and characterization of PVDF-conjugated polymer nanofiber-based systems. Five different conducting polymers (CPs) were synthesized successfully and used to create the nanofiber systems. The CPs used are polyaniline (PANI), polypyrrole (PPY), polyindole (PIN), polyanthranilic acid (PANA), and polycarbazole (PCZ). Nanofiber systems were produced utilizing the Forcespinning® technique. The nanofiber systems were developed by mechanical stretching. No electrical field or post-process poling was used in the nanofiber systems. The morphology, structure, electrochemical and piezoelectric performance was characterized. All of the nanofiber PVDF/CP systems displayed higher piezoelectric performance than the fine fiber PVDF systems. The PVDF/PPY nanofiber system displays the highest piezoelectric performance of 15.56 V. The piezoelectric performance of the PVDF/CP nanofiber systems favors potential for an attractive source of energy where highly flexible membranes could be used in power actuators, sensors and portable, and wireless devices to mention some. 相似文献
2.
Geraint Johnes Swati Virmani 《International Transactions in Operational Research》2020,27(4):1869-1885
Data from the Young Lives study are used to evaluate the efficiency of education systems in four low and middle income countries: Ethiopia, India, Peru and Vietnam. A meta‐frontier variant of data envelopment analysis is used to assess the relative performance of each country's system, and, within each country, to evaluate the impact of public and private schooling, and of urban and rural location. Comparisons are drawn between the four countries; the results indicate that in no country does the educational system perform uniformly badly or well. Conditioning on the inputs available, rural areas are often indicative of higher levels of efficiency, thus suggesting a number of implications for policy. 相似文献
3.
The nature of pairing mechanism as well as transition temperature of yttrium cuprates is discussed using the strong coupling
theory. An interaction potential has been developed for the layered structure with two conducting CuO2(a–b) layers in a unit cell. The interaction potential properly takes care of electron-electron, electron-phonon and electron-plasmon
interactions. Furthermore, the electron-phonon coupling parameter (λ), the modified Coulomb repulsive parameter (μ*) and the 2D acoustic phonon (plasmon) energy as a function of oxygen deficiency is worked out. Finally, the superconducting
transition temperature (T
c) is then evaluated by using these coupling parameters and obtainedT
c = 95(92)K for Y(Yb)Ba2Cu3O7−δ
superconductors withδ = 0·0. The model parameters estimated from the layered structure approach are consistent with the strong coupling theory.
The result deduced on the variation ofT
c withδ are in fair agreement with the earlier reported data on yttrium cuprates. The analysis of the above results are discussed. 相似文献
4.
We study the mechanical and conformational properties of networks of helical polymers with a combination of Monte Carlo simulations based on the Wang-Landau algorithm and the three-chain model. We find that the stress-strain behavior of these networks has novel features not observed in typical networks made of synthetic polymers. In particular, we find that as these networks are stretched they first strengthen, then soften and finally strengthen again. This non-monotonic behavior of the stress correlates with the one of the helical content and is rationalized by the elongation-induced formation and melting of the helical structure of the polymer. We complement these results with a study of other conformational properties of the polymer strands that clarify the molecular mechanisms behind the mechanical behavior of these networks. Finally, we present a qualitative comparison of some of our results with the theoretical ones recently reported by Kutter and Terentjev. 相似文献
5.
A signal intensity based maximum-likelihood (ML) target location estimator that uses quantized data is proposed for wireless sensor networks (WSNs). The signal intensity received at local sensors is assumed to be inversely proportional to the square of the distance from the target. The ML estimator and its corresponding Crameacuter-Rao lower bound (CRLB) are derived. Simulation results show that this estimator is much more accurate than the heuristic weighted average methods, and it can reach the CRLB even with a relatively small amount of data. In addition, the optimal design method for quantization thresholds, as well as two heuristic design methods, are presented. The heuristic design methods, which require minimum prior information about the system, prove to be very robust under various situations 相似文献
6.
Mathematical models for chemical reaction and mass transfer occurring in the manufacture of high-viscosity condensation polymers are considered. A preliminary study indicates that several diverse models can be represented using a single formula based upon an effectiveness factor. The effectiveness factor is shown to depend upon a ratio of time scales of mixing and reaction. The formula giving the effectiveness factor in terms of the time scales ratio is shown to depend upon mixing assumptions only. Starting with a mixing-cell model, a new modeling framework is developed and shown to include the previous models as special cases. The framework is free of inherent mixing assumptions and can be applied to a wide variety of situations once the mixing characteristics are specified. © 1993 John Wiley & Sons, Inc. 相似文献
7.
Solomon Sundar Manoharan Swati Sigamani John Prasanna Manju Lata Rao Ranjan Kumar Sahu 《Journal of the American Ceramic Society》2002,85(10):2469-2471
Interaction of electromagnetic radiation with a physical mixture of metal nitrates and amides/hydrazides is observed to initiate high-temperature reactions, useful for realizing several high-temperature ceramic materials. A judicious choice of such redox mixtures undergoes exothermic reactions when they couple with microwave radiation. The coupling of electromagnetic radiation with metal salts and amides/hydrazides depends on the dielectric properties of the individual components in the reaction mixture. The approach has been used to prepare γ-Fe2 O3 , Fe3 O4 , MgCr2 O4 , α-CaCr2 O4 , and La0.7 Ba0.3 MnO3 . 相似文献
8.
Sinha Swati Shaw Siddharth Biswas Kunal De Debashis Das Samir Chandra Sarkar Angsuman Bandyopadhyay Jaya 《Microsystem Technologies》2021,27(11):4087-4100
Microsystem Technologies - Single-Walled Carbon Nanotubes (SWCNTs) are widely used as potential carriers in drug delivery systems. The objective of this work was to observe the effects of pristine,... 相似文献
9.
Usha Varshney R. J. Churchill H. P. Groger A. I. Kingon 《Journal of Superconductivity》1989,2(2):293-304
Recent advances in the fabrication of high-T
c
superconducting thick films demand processing techniques which can eliminate film/substrate interdifiusion that occurs during subsequent post-annealing heat treatment after the film is deposited, thereby limiting the application of the thick films for devices. The present study evaluates laser annealing techniques for plasma-deposited Y-Ba-Cu-O thick films using a high-energy CO2 laser (10.6m) in a continuous wave mode. The results are compared with those obtained by conventional furnace annealing techniques necessary for post-heat treatment of as-deposited superconducting thick films. The high-T
c
superconducting phase is recovered by cationic diffusion during subsequent post-annealing heat treatment. Crystallographic phases and microstructural characterization have been performed using XRD, SEM, and EPMA analytical techniques. The significance of the technology lies in the elimination of film/substrate interdiffusion problems, thereby resulting in high-quality superconducting thick films. The technology will significantly reduce the post-annealing times usually required by conventional furnace annealing techniques. 相似文献