MAT: a Mobile Agent System for supporting autonomous mobile agents

Abstrac

Identifying Potential synthesis cases in distributed expert systems: a fuzzy logic approach

Abstrac

A Certificateless Ring Signature Scheme with High Efficiency in the Random Oracle Model

Ring signature is a kind of digital signature which can protect the identity of the signer. Certificateless public key cryptography not only overcomes key escrow problem but also does not lose some advantages of identity-based cryptography. Certificateless ring signature integrates ring signature with certificateless public key cryptography. In this paper, we propose an efficient certificateless ring signature; it has only three bilinear pairing operations in the verify algorithm. The scheme is proved to be unforgeable in the random oracle model

Optimal Design for the Blunt Trailing-Edge Profile of Wind Turbine Airfoils under Glaze Ice Conditions

Glaze ice is more likely to occur on the rotating blade, and greatly decreases the energy utilization efficiency of wind turbines. Moreover, due to its complex and irregular shape, a high-quality grid and more grid cells are needed in aerodynamic calculation. To improve this situation, this study develops a novel multiobjective optimization method for the blunt trailing edge of airfoils under glaze ice conditions. The parametric representation of the asymmetric trailing-edge profile is given by the B-spline function. The aerodynamic coefficients of the airfoils without and with glaze ice are calculated using the computational fluid dynamics (CFD) method and back propagation (BP) neural network, respectively. The update mode of the potential well center of nonoptimal particles is modified by the social learning and the optimal particle position is identified using the Lévy flight and greedy algorithm for quantum particle swarm optimization (QPSO) algorithm. The optimizer based on the improved QPSO algorithm integrated with CFD method and BP network seeks the trailing-edge control parameters maximizing the lift coefficient and lift-drag ratio. The lift and drag coefficients, lift-drag ratios, and pressure contours of the original and optimized airfoils are investigated before and after icing. Significant improvements of the aerodynamic performance are achieved in this process, confirming that the presented method constitutes a valuable tool for the airfoil design of wind turbines operating in icing conditions

A generality analysis of multiobjective hyper-heuristics

Selection hyper-heuristics have emerged as high level general-purpose search methodologies that mix and control a set of low-level (meta) heuristics. Previous empirical studies over a range of single objective optimisation problems have shown that the number and type of low-level (meta) heuristics used are influential to the performance of selection hyper-heuristics. In addition, move acceptance strategies play an important role and can significantly affect the overall performance of a hyper-heuristic. In this paper, we introduce an adapted variant of an existing learning automata based multiobjective hyper-heuristic from the literature. We investigate the performance and generality level of the proposed method, and another learning automata based selection hyper-heuristic, operating over a search space of multiobjective evolutionary algorithms (MOEAs) across two well-known multiobjective optimisation benchmarks. The experimental results demonstrate that, regardless of the number and type of low-level metaheuristics available, the learning automata based hyper-heuristics outperform each constituent MOEA individually, and an online learning and random choice selection hyper-heuristic from the literature. This performance and generality is shown to be consistent across a number of different move acceptance strategies

Social risk factors of transportation PPP projects in China: A sustainable development perspective

Public-private partnerships (PPPs) have become increasingly important in improving the sustainability of society in China, with transportation being the largest investment area. However, the Social Risk Factors (SRFs) of transportation PPPs in China, which serve as a useful tool for distinguishing strengths and weaknesses for effective social risk management (SRM), have not been clearly identified. A conceptual model including 3 risk dimensions and 15 SRFs was proposed to mitigate social risks and improve the social sustainability of transportation PPP projects. A questionnaire survey conducted to investigate stakeholders’ opinions on the proposed SRFs demonstrated that all the SRFs were important. The SRFs can be used to evaluate social risks from economic, environmental, and social dimensions. Confirmatory factor analysis (CFA) verified the classification of the SRFs and indicated that all the risk dimensions contributed to social risks. The social and environmental impacts on social sustainability may contribute more to the generation of social risks. Furthermore, the concept of people-first PPPs was proposed to reduce social risks from the perspective of different stakeholders, with the interactions among different stakeholders being prioritized. The identified SRFs and their relationships can improve our understanding of SRM in the delivery of social sustainability and improve social resilience

Effects of depression, diabetes distress, diabetes self-efficacy, and diabetes self-management on glycemic control among Chinese population with type 2 diabetes mellitus

Aim To examine the direct and indirect effects of depression, diabetes distress, diabetes self-efficacy and diabetes self-management on glycemic control among a group of T2DM patients in China. Method A convenience sample of 254 participants were selected from three outpatient departments in Beijing, China. They were surveyed using a self-administered questionnaire. Diabetes-related information was retrieved from their medical records. Descriptive statistics, independent student t tests, Chi-square tests, correlation analyses and Generalized Structural Equation Modeling were used. Results Only 91 (35.82%) participants achieved optimal glycemic control of HbA1c < 7.0% (53 mmol/mol). Only diabetes self-management had a direct effect on glycemic control (OR = 0.95, P < 0.001). Depression and diabetes distress had only indirect effects on glycemic control through both diabetes self-efficacy and diabetes self-management. Diabetes self-efficacy only had an indirect effect on glycemic control through diabetes self-management. Conclusions Glycemic control among Chinese population with T2DM was suboptimal. Future interventions should focus on decreasing depressive symptoms and diabetes distress levels, and, therefore, improve diabetes self-efficacy and self-management practices and, ultimately, reach the optimal goal of glycemic control. © 2017 Elsevier B.V

An engineering route to synthesize stable bulk nanocrystalline magnesium with an average grain size of 20 nm

A simple and effective route to preparing bulk nanocrystalline (NC) pure Mg with an average grain size of 20 nm is first proposed by hydrogenation-disproportionation-desorption-recombination (HDDR) followed by spark plasma sintering (SPS) and hot extrusion (HE) techniques. NC Mg is thermodynamically super-stable against annealing at 550 °C and straining under compression and tension. Moreover, the as-extruded NC Mg samples show high tensile yield stress (TYS) of 259 MPa and compressive yield strength (CYS) of 157 MPa, which are about 2 times and about 7–10 times higher than those of their coarse-grain counterparts and the as-cast samples, respectively

Real-Time H∞ Control of Networked Inverted Pendulum Visual Servo Systems

Aiming at the challenges of networked visual servo control systems, which rarely consider network communication duration and image processing computational cost simultaneously, we here propose a novel platform for networked inverted pendulum visual servo control using H∞ analysis. Unlike most of the existing methods that usually ignore computational costs involved in measuring, actuating and controlling, we design a novel event-triggered sampling mechanism that applies a new closed-loop strategy to dealing with networked inverted pendulum visual servo systems of multiple time-varying delays and computational errors. Using Lyapunov stability theory, we prove that the proposed system can achieve stability whilst compromising image-induced computational and network-induced delays and system performance. In the meantime, we use H∞ disturbance attenuation level γ for evaluating the computational errors, whereas the corresponding H∞ controller is implemented. Finally, simulation analysis and experimental results demonstrate the proposed system performance in reducing computational errors whilst maintaining system efficiency and robustness

Theoretical model of the nonlinear resonant interaction of whistler-mode waves and field-aligned electrons

The nonlinear resonant interaction of intense whistler-mode waves and energetic electrons in the Earth’s radiation belts is traditionally described by theoretical models based on the consideration of slow-fast resonant systems. Such models reduce the electron dynamics around the resonance to the single pendulum equation, that provides solutions for the electron nonlinear scattering (phase bunching) and phase trapping. Applicability of this approach is limited to not-too-small electron pitch-angles (i.e., sufficiently large electron magnetic moments), whereas model predictions contradict to the test particle results for small pitch-angle electrons. This study is focused on such field-aligned (small pitch-angle) electron resonances. We show that the nonlinear resonant interaction can be described by the slow-fast Hamiltonian system with the separatrix crossing. For the first cyclotron resonance, this interaction results in the electron pitch-angle increase for all resonant electrons, contrast to the pitch-angle decrease predicted by the pendulum equation for scattered electrons. We derive the threshold value of the magnetic moment of the transition to a new regime of the nonlinear resonant interaction. For field-aligned electrons the proposed model provides the magnitude of magnetic moment changes in the nonlinear resonance. This model supplements existing models for not-too-small pitch-angles and contributes to the theory of the nonlinear resonant electron interaction with intense whistler-mode waves.</div