To analyze the feasibility of electrospinning nanofiber yarn using a wrapping yarn forming device, electrospun nanofiber-wrapped yarns and multiscale yarns were prepared by self-made equipment. The relationship between the surface morphology and properties of yarn and its preparation process was studied. The process parameters were adjusted, and it was found that some nanofibers formed Z-twisted yarns, while others showed exposed cores. To analyze the forming mechanism of electrospun nanofiber-wrapped yarn, the concept of winding displacement difference in the twisted yarn core A was introduced. The formation of nanofiber-wrapped structural yarns was discussed using three values of A. The starting point of each twist was the same position when A = 0 with a constant corner angle β. However, the oriented nanofiber broke or was pulled out from the gripping point when it was twisted, and it appeared disordered. The forming process of electrospun nanofiber-wrapped yarn displayed some unique phenomena, including the emission of directional nanofibers during collection, fiber non-continuity, and twist angle non-uniformity. The conclusions of this research have theoretical and practical value to guide the industrial preparation of nanofiber yarns and their wrapped yarns.
Usually, the optimal spinning reserve is studied by considering the balance between the economy and reliability of a power system. However, the uncertainties from the errors of load and wind power output forecasting have seldom been considered. In this paper, the optimal spinning reserve capacity of a power grid considering the wind speed correlation is investigated by Nataf transformation. According to the cost-benefit analysis method, the objective function for describing the optimal spinning reserve capacity is established, which considers the power cost, reserve cost, and expected cost of power outages. The model was solved by the quantum-behaved particle swarm optimization (QPSO) algorithm, based on stochastic simulation. Furthermore, the impact of the related factors on the optimal spinning reserve capacity is analyzed by a test system. From the simulation results, the model and algorithm are proved to be feasible. The method provided in this paper offers a useful tool for the dispatcher when increasing wind energy is integrated into power systems.
Reinforcement of fibers was carried out by adding carbon black (CB), and hydroxylated and carboxylated carbon nanotubes (CNTs) into electrospinning solution containing doped polyaniline (CSA-PANI) and polyacrylonitrile (PAN). CB/CSA-PANI/PAN and CNT/CSA-PANI/PAN electrospun nanofiber composite membrane was formed in high-voltage electric field. The CSA-PANI/CB/PAN fiber membrane was found to be more brittle than the MWCNTs/CSA-PANI/PAN fiber membrane. The average diameter of the CSA-PANI/CB/PAN nanofibers increased with CB addition, while the average diameter of CNT-added MWCNTs/CSA-PANI/PAN nanofibers decreased with increasing CNT concentrations. Upon greater CB and CNT addition, agglomeration occurred, and the surface of the fibers was raised slightly. The fracture strength of the nanofiber membrane was greatly improved with 1% added CB but then decreased upon further CB addition. Upon addition of CNTs, the fracture strength of the nanofiber membrane first increased and then decreased, and the addition of carboxylated CNTs was more advantageous for improving the fracture strength of the fiber membrane. The electromagnetic shielding performance of the fiber membranes was essentially the same for different radiation frequencies. Upon addition of CB and CNTs, the electromagnetic shielding performance of the fiber first increased and then decreased, with a more pronounced decrease obtained by the addition of CB.
In this paper, the thermal conductivity and optical properties of [Formula: see text]- and [Formula: see text]-nitrogene have been investigated by the first principles of density functional theory. Phonon dispersion suggests that [Formula: see text]- and [Formula: see text]-nitrogene are stable. The thermal conductivity of [Formula: see text]-nitrogene is almost isotropic and has a thermal conductivity of 960.17 W/m[Formula: see text]K at 300 K. The thermal conductivity of [Formula: see text]-nitrogene is anisotropic, which has a thermal conductivity of 12.34 W/m[Formula: see text]K and 18.59 W/m[Formula: see text]K along with the armchair and zigzag directions at 300 K, respectively. The acoustic phonon branches (TA, LA, and ZA) play a dominant role in heat transport in [Formula: see text]-nitrogene. But optical dispersions play an important role in the heat transport of [Formula: see text]-nitrogene. With the larger Grüneisen parameter and smaller phonon lifetime of [Formula: see text]-nitrogene, [Formula: see text]-nitrogene exhibits a smaller thermal conductivity than that of [Formula: see text]-nitrogene significantly. In addition, optical properties of [Formula: see text]- and [Formula: see text]-nitrogene have been researched. Meanwhile, [Formula: see text]-nitrogene has a certain absorption effect on the visible spectrum and ultraviolet light. Thus, the nitrogene allotropes have different optoelectronic properties. Moreover, nitrogene can be used to fabricate optoelectronic devices. This work provides a theoretical description of the thermal conductivity and photoelectricity of nitrogene allotropes.
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