Full-conjugated rod-rod structures comprising patched-fibrillar, ringed-fibrillar, and double-fibrillar configurations were designed from poly(3-hexylthiophene) (homo-P3HT) and polyaniline (PANI) nanorods in chloroform, p-xylene, and amyl acetate dilute solutions, respectively. Solvent quality, seeding effect, and constituent material were focused while characterizing the developed structures. By exacerbating the processing solvent quality from chloroform to p-xylene, a ringed-fibrillar configuration was detected instead of patched-fibrillar structure. In a poor solvent, double-fibrillar structures were acquired from homo-P3HT chains and PANI nanorods. Towards a poorer solvent, P3HT chains were capable of developing their own crystals by less sensing presence of PANI nanorods as seeds. In another experiment, by copolymerization of both P3HT and PANI with crystallizable PEG blocks, sandwiched rod-rod mixed-brush single crystals were developed. Molecular weight of neither P3HT nor PANI was effective on surface patterning of P3HT/PANI mixed-brushes. Via elevating crystallization temperature, PANI dispersed patterns became more delicate and their width decreased from 80 to 160 nm to 12–30 nm. P3HT backbones were tethered with a extended flat-on orientation onto the PEG substrate at either low or high crystallization temperatures. Beside sandwiched single crystals seeded with homo-PEG tiny crystals, slightly and highly curved half-ring crystals were also developed in the PEG-b-P3HT systems.
Radial basis functions (RBFs) are extensively employed in mesh-free methods owing to their distinct properties. This study presents a novel RBF formulation based on a modified first-kind Bessel function, introduced for the first time. The efficacy and precision of the proposed function are assessed through an examination of the free vibrations of Euler–Bernoulli beams composed of two-directional functionally graded materials. Longitudinal and thickness property variations are modeled in polynomial and exponential forms, respectively. The performance of the novel RBF is scrutinized under various boundary conditions (clamped, simply supported, and free), and comparative analyses are conducted against similar investigations and an RBF based on the first-kind Bessel function. Convergence analysis of the proposed modified first-kind Bessel function-based RBF reveals superior convergence rates compared to the first-kind Bessel function-based RBF. Moreover, a comparison between results obtained from modeling using the proposed RBF and exact solutions underscores the adequacy of this approach, with a maximum discrepancy of 4.933% observed under clamped-free boundary conditions. In essence, the findings suggest that the proposed modified first-kind Bessel function-based RBF holds promise for analyzing the free vibrations of functionally graded Euler–Bernoulli beams. The primary aim of this research is to introduce and validate a new RBF based on a modified first-kind Bessel function for the analysis of free vibrations in Euler–Bernoulli beams made of two-directional functionally graded materials. The study focuses on evaluating the performance and accuracy of this novel RBF in comparison with existing RBFs and exact solutions. By addressing the limitations of conventional RBFs and proposing an innovative approach, this research aims to enhance the accuracy and efficiency of meshless methods in structural vibration analysis. 相似文献
In this study, fracture toughness of functionally graded steels in both crack divider and crack arrester configurations has
been studied. Spot-welded plain carbon steel and austenitic stainless steel with different thicknesses and arrangements were
used as electrodes of electroslag remelting to produce functionally graded steels. Fracture toughness of the specimens in
crack divider configuration was found to depend on the arrangements of the primary electrodes’ pieces together with the type
of the containing phases. In crack arrester configuration, the fracture toughness was found to depend on the crack tip position
and the distance of the crack tip with respect to the bainitic or martensitic intermediate layers. 相似文献
It is believed that fossil fuel sources are exhaustible and also the major cause of greenhouse gas emission. Therefore, it is required to increase the portion of renewable energy sources in supplying the primary energy of the world. In this study, it is focused on application of nanotechnology in exploitation of renewable energy sources and the related technologies such as hydrogen production, solar cell, geothermal, and biofuel. Here, nanotechnologies influence on providing an alternative energy sources, which are environmentally benign, are comprehensively discussed and reviewed. Based on the literature, employing nanotechnology enhances the heat transfer rate in photovoltaic/thermal (PV/T) systems and modifies PV structures, which can improve its performance, making fuel cells much cost‐effective and improving the performance of biofuel industry through utilization of nanocatalysts, manufacturing materials with high durability and lower weight for wind energy industry. 相似文献
The present work concerns the parametric study and optimization of regenerative Clausius and organic Rankine cycles (ORC) with two feedwater heaters. For the parametric optimization, thermal efficiency, exergy efficiency and specific work are selected as the objective functions, so the mentioned parameters are calculated for different values of the outlet pressures from the second and third pumps by using EES (Engineering Equation Solver) software. Aiming at optimizing these functions, a procedure based on artificial neural network (ANN) and artificial bees colony (ABC) is proposed. The procedure includes two stages. According to the obtained data from the parametric analysis, in the first stage three different multi-layer perceptron neural networks are trained. In the next stage, three distinct artificial neural networks are used to optimize the specific network, the thermal efficiency and the exergy efficiency. Variables and fitness functions in these algorithms are the inputs and the outputs of the corresponding trained neural network, respectively. This optimization process is applied to water for a Clausius Rankine cycle and also to R717 for an ORC. It is shown that some interesting features among optimal objective functions and decision variables involved in this power cycle can be discovered consequently. 相似文献
In relay-assisted cooperative com-munication, relay nodes help forwarding the information of a source node in case of link failure between the source and a destination. Although user cooperation improves the over-all efficiency of the network, it requires incen-tive to stimulate potential relay nodes to assist the source by forwarding its data to the desti-nation. Moreover, the potential relays are bet-ter informed than the source about their chan-nel conditions to destination, which results in asymmetric information between the source and the relays. In this paper, we study the problem of lack of forwarding incentive in cooperative communication when channel state information of relays is private infor-mation and not known by the source. To tackle this problem, we apply the principle of contract theory to a cooperative wireless system. Source first designs incentive compatible and individually rational contract, consisting of a set of power-credit pairs. Then it broadcasts contract items to nearby nodes. Once the source node receives reply messages from the volunteer relays, it chooses one or more relays based on its re-quirements and communication starts. Simulation results show how credit assignment works in order to stimulate relays to cooperate and prevents relays from cheating behavior. 相似文献
Excessive synchronous firing of neurons is the sign of several neurological disorders such as Parkinson and epilepsy. In addition, growing evidence suggests that astrocytes have significant roles in neural synchronization. Drawing on these concepts and based on the latest studies, a bio-inspired stimulator which essentially is a dynamical model of the astrocyte biophysical model is proposed. The performance of the proposed bio-inspired stimulator is investigated on a large-scale, sparsely connected neural network which models a local cortical population. Next, a multiplier-less digital circuit for the bio-inspired stimulator is designed, and finally, the complete digital circuit of the closed-loop system is implemented in hardware on the ZedBoard development kit. Considering software simulations and hardware FPGA implementation, the proposed bio-inspired stimulator is able to prevent the hyper-synchronous neural firing in a network of excitatory and inhibitory neurons. Based on the obtained results, it is demonstrated that the proposed stimulator has a demand-controlled characteristic and can be a good candidate as a new deep brain stimulation (DBS) technique to effectively suppress the hyper-synchronous neural oscillations.
