Narrow Results

In multi-agent system (MAS), the communication topology of agent network plays a very important role in its collaboration. Small-world networks are the networks with high local clustering and small average path length, and the communication networks of MAS can be analyzed within the frame of small-world topology. Yet the real multiagent communication networks are abundant and the classical WS small-world model is not suitable for all cases. In this paper, two new small-world network models are presented. One is based on random graph substrate and local nodes preference reconnection and the other is based on regular graph substrate and long-range nodes preference reconnection. The characteristic of the network parameter such as the clustering coefficients, average path length, and eigenvalue λ₂ and λ_n of the Laplacian matrix for these two models and WS model is studied. The consensus problem that based on these three models is also studied. An example is given and the conclusions are made in the end.

A mathematical model of vibration power generation (VPG) with the giant magnetostrictive material (GMM) is proposed on the basis of the magneto-mechanical coupling model, Jiles-Atherton model and electromagnetic induction law. According to the model, the output voltage of a giant magnetostrictive power generator has been calculated under the condition of different vibration frequency, pre-stress and bias magnetic field. The calculating results show that the model can reveal the relationship between the input vibrating stress and output voltage. The experiment of a giant magnetostrictive power generator has been carried out, and the experimental results agree well with the calculating results.

In this paper, our focus is on ABA trilayer graphene nanoribbon (TGN), in which the middle layer is horizontally shifted from the top and bottom layers. The conductance model of TGN as a FET channel is presented based on Landauer formula. Besides the good reported agreement with experimental study lending support to our model, the presented model demonstrates that minimum conductivity increases dramatically by temperature. It also draws parallels between TGN and bilayer graphene nanoribbon, in which similar thermal behavior is observed. Maxwell–Boltzmann approximation is employed to form the conductance of TGN near the neutrality point. Analytical model in degenerate regime in comparison with reported data proves that TGN-based transistor will operate in degenerate regime like what we expect in conventional semiconductors. Moreover, our model confirms that in similar condition, the conductivity of TGN is less than bilayer graphene nanoribbon as reported in some experiments.

A new model for efficiency droop in InGaN/GaN light-emitting diodes (LEDs) is proposed, where the primary nonradiative recombination mechanisms, including Shockley–Read–Hall (SRH), Auger and carrier leakage, are considered. A room-temperature external quantum efficiency (EQE) measurement was performed on our designed samples and analyzed by the new model. Owing to advantages over the common “$ABC+f(n)$ model”, the “new model” is able to effectively extract recombination coefficients and calculate the leakage currents of the hole and electron. From this new model, we also found that hole leakage is distinct at low injection, while it disappears at high injection, which is contributed to the weak blocking effect of electron in quantum wells (QWs) at low injection.

An extended lattice hydrodynamic model with time delay is proposed under non-lane discipline. We try to grasp the impacts of the non-lane discipline of the considered lattice sites. Linear stability analysis of the proposed model is executed and the stability criterion is obtained. Using the reductive perturbation method, we investigate nonlinear analysis of the proposed model and derive the mKdV equation and its solution, which could reveal the propagation of density waves. We analyze the effect of time delay, the ratio of lane deviation and the control coefficient on the stability of traffic flow via numerical experiments. We find that those indices play an important role in the stability of traffic flow. The longer the time delay, the more unstable the system becomes. Also, the ratio of lane deviation and the control coefficient is able to more quickly dissipate the traffic congestions occurring in traffic flow.

This research attempts to explore the utilization of Gas-Assisted Electrical Discharge Machining (GAEDM) of die steel. High pressure inert gas (argon) in conventional electric discharge machining with constraint state was utilized to assess the surface roughness (SR). Analysis of Variance (ANOVA) was used to find out the process parameters that notably affected the SR. In this study, a mathematical model has been investigated to know the SR by using Buckingham pie-theorem. The fit summary confirmed that the quadratic model is statistically appropriate and the lack of fit is insignificant. Root mean square error and absolute standard deviation, obtained through response surface method (RSM), were also used for developing the model and for predicting its abilities through ANN, ANFIS. The experiment and anticipated estimates of SR during the process, obtained by RSM, dimensional analysis, ANN and ANFIS, were found to be in accord with each other. However, the ANFIS technique proved to be more fitting to the response as compared to the ANN, dimensional analysis and the RSM.

This short review highlights the author’s group research on modified vitamin B${}_{12}$ derivatives with a peptide backbone as (1) inhibitors of B${}_{12}$-dependent enzymes and as (2) models of cofactor B${}_{12}$-protein complexes.

Thin-film deposition processes have gained much popularity due to their unique capability to enhance the physical and chemical properties of various materials. Identification of the best parametric combination for a deposition process to achieve desired coating quality is often considered to be challenging due to the involvement of a large number of input process parameters and conflicting responses. This study discusses the development of adaptive neuro-fuzzy inference system-based models for the prediction of quality measures of two thin-film deposition processes, i.e., SiCN thin-film coating using thermal chemical vapor deposition (CVD) process and Ni–Cr alloy thin-film coating using direct current magnetron sputtering process. The predicted response values obtained from the developed models are validated and compared based on actual experimental results which exhibit a very close match between both the values. The corresponding surface plots obtained from the developed models illustrate the effect of each process parameter on the considered responses. These plots will help the operator in selecting the best parametric mix to achieve enhanced coating quality. Also, analysis of variance results identifies the importance of each process parameter in the determination of response values. The proposed approach can be applied to various deposition processes for modeling and prediction of observed response values. It will also assist as an operator in selecting the best parametric mix for achieving desired response values.

At high temperatures above 1650°C, the SiC-depleted layer of ultra-high-temperature ceramics which has high porosity appears during the oxidation process. In this present paper, based on the studies of the oxidative mechanisms and the fracture mechanisms of ultra-high-temperature ceramics under normal and high temperatures, a thermo-damage strength model for the SiC-depleted layer on high temperature oxidation was proposed. Using the model, the phase transformation, microstructure development and fracture performance in the SiC-depleted layer on high temperature oxidation were studied in detail. The study showed that the porosity is mainly related to the oxidation of SiC. And while the SiC is substantially completely oxidized, only a very small part of matrix is oxidized. The fracture strength of the SiC-depleted layer degrades seriously during the high temperature oxidation process. And the bigger the initial volume fraction of SiC, the lower the fracture strength of the SiC-depleted layer is. This layer may become the origin of failure of material, thus the further researches should be undertaken to improve the oxidation behavior for the ultra-high-temperature ceramics in a wider temperature range.

Twisted and coiled polymer actuators (TCPAs), an emerging class of artificial muscles, exhibit the advantages of large stroke, low hysteresis, low cost, etc. The effect of design parameters on thermal actuation is important for the effective design of TCPAs. In this study, a new model has been developed to describe the effect of geometrical parameters on thermal actuation based on Castigliano’s second theorem. In this model, an equivalent modulus based on its radial bias angle has been introduced from the twisted polymer actuator (TPA)’s equivalent model. The proposed model provides a simple and accurate expression to describe the TCPA’s thermal actuation by using its fundamental characteristic. The proposed model was validated with respect to the experimental data from the literature and subsequently used in the parametric analysis of TCPA. The numerical results show that the amplitude of actuation increases linearly with pitch angle and nonlinearly with spring index.

Lignin-based carbon nanomaterials (LCN) were prepared from alkaline lignin (AL) by hydrolysis, spray drying and high temperature treatment. Then, the physical and chemical structures of LCN were analyzed by SEM, BET, organic element analyzer, FTIR, Raman, UV–vis and XPS. The results showed that the yield of LCN was 26.34% of the mass of AL. The particle size of LCN was 120–350 nm, and three to seven particles with diameter of 40–100 nm are accumulated. Its specific surface area was 374.74 m²/g with the average pore size of 4.79 nm. The ratio of sp² to sp³ was 1.39 and the band gap was 3.42 eV. The simplified apparent formula of LCN was C${}_{21}$H₄O with an unsaturation of 20, containing C–C, C=C, C–O, O=C–O and C–H groups. The chemical structure model of LCN was constructed by Chem 3D software. Therefore, this study successfully prepared a special material and analyzed its physical and chemical structure, which was conducive to the structural analysis of carbon nano-materials.

Flexible dielectric composites with high permittivity have been extensively studied due to their potential applications in high-density energy capacitors. In this review, effects of interface characteristics on the dielectric properties in the polymer-based nanocomposites with high permittivity are analyzed. The polymer-based dielectric composites are classified into two types: dielectric–dielectric (DD, ceramic particle-polymer) composites and conductor–dielectric (CD, conductive particle-polymer) composites. It is highly desirable for the dielectric–dielectric composites to exhibit high permittivity at low content of ceramic particles, which requires a remarkable interface interaction existing in the composite. For conductor–dielectric composites, a high permittivity can be achieved in composite with a small amount of conductor particle, but associated with a high loss. In this case, the interface between conductor and polymer with a good insulating characteristic is very important. Different methods can be used to modify the surface of ceramic/conductor particles before these particles are dispersed into polymers. The experimental results are summarized on how to design and make the desirable interface, and recent achievements in the development of these nanocomposites are presented. The challenges facing the fundamental understanding on the role of interface in high-permittivity polymer nanocomposites should be paid a more attention.

0-3 dielectric composites with high dielectric constants have received great interest for various technological applications. Great achievements have been made in the development of high performance of 0-3 composites, which can be classified into dielectric–dielectric (DDCs) and conductor–dielectric composites (CDCs). However, predicting the dielectric properties of a composite is still a challenging problem of both theoretical and practical importance. Here, the physical aspects of 0-3 dielectric composites are reviewed. The limitation of current understanding and new developments in the physics of dielectric properties for dielectric composites are discussed. It is indicated that the current models cannot explain well the physical aspects for the dielectric properties of 0-3 dielectric composites. For the CDCs, experimental results show that there is a need to find new equations/models to predict the percolative behavior incorporating more parameters to describe the behavior of these materials. For the DDCs, it is indicated that the dielectric loss of each constituent has to be considered, and that it plays a critical role in the determination of the dielectric response of these types of composites. The differences in the loss of the constituents can result in a higher dielectric constant than both of the constituents combined, which breaks the Wiener limits.

The characteristics of the electromechanical response observed in an ionic-electroactive polymer (i-EAP) are represented by the time ($t$) dependence of its bending actuation ($y$). The electromechanical response of a typical i-EAP — poly(ethylene oxide) (PEO) doped with lithium perchlorate (LP) — is studied. The shortcomings of all existing models describing the electromechanical response obtained in i-EAPs are discussed. A more reasonable model: $y=y_{max}{e}^{-\tau ∕t}$ is introduced to characterize this time dependence for all i-EAPs. The advantages and correctness of this model are confirmed using results obtained in PEO-LP actuators with different LP contents and at different temperatures. The applicability and universality of this model are validated using the reported results obtained from two different i-EAPs: one is Flemion and the other is polypyrrole actuators.

Droughts are severe meteorological disasters in China, and more comprehensive evaluation methods for droughts can provide a reliable reference for policy-making in reducing the impact of droughts. The existing methods of drought evaluation are lacking universally, and cannot be used generally. Based on the theory of Variable Fuzzy Sets, a comprehensive drought evaluation model is proposed to solve the problem. The methodology for the proposed solution is written in this paper and is applied in the Qucun Yellow River Irrigation Region. The results have shown that the model is not only reasonable and feasible, but also simple and practical. The model and its methods can provide academic support and serve as reference for policy-making for the comprehensive evaluation of droughts in the North Region of China.