Abstract: Aimed at the complexity of engine vibration, the paper proposed a combination method of wavelet packet and support vector machine for engine fault diagnosis based on the vibration signals. The vibration signals were collected from a gasoline engine, which type is Dongfeng EQ6100 (Chinese engine). The signals cover four working conditions, i.e. normal, piston knocking, piston pin fault, crankshaft bearing fault, under two engine conditions of on- and off-ignition, respectively. Firstly, wavelet packet was used to extract the features of the signals. Then, the off-ignition signals were selected to be the training data to construct a multi-class classifier based on support vector machine (SVM). Finally, applied the classifier to the engine diagnosis, and the faults were recognized effectively. The results demonstrate that the combined method is suitable to diagnose engine faults, especially for small signal samples.
Abstract: To effectively solve the problems of high energy consumption, low control accuracy and time control-delay for furnace, this paper proposes the intelligent control strategies based on the process feature of walking beam furnace, namely fuzzy-RBF network self-learning and self-optimizing function, which is combined with dynamic PID feedback compensation strategy. The experiment shows that the system not only guarantees the furnace temperature control accuracy and increases the temperature up and down rate under working condition fluctuation, which reduces unit fuel consumption, unit electricity consumption and billet burning loss, but also improves the furnace production capacity.
Abstract: Extending the investigations on (Na0.5K0.5)NbO3-based solid solution for lead-free piezoelectric ceramics, this paper consider the complex solid-solution system (Na0.5K0.5)NbO3–Bi0.5(Na0.80K0.20)0.5TiO3 [NKN-BNKT]. (Na0.5K0.5)NbO3 with 2 ~ 6 mol% Bi0.5(Na0.80K0.20)0.5TiO3 has been prepared following the conventional mixed oxide process. A morphotropic phase boundary (MPB) between orthorhombic (O) and tetragonal (T) was found at the composition 0.97NKN-0.03BNKT with correspondingly enhanced dielectric and piezoelectric properties. The electromechanical coupling factor and dielectric constant are higher for compositions near the MPB. The dielectric constant (εr), planar coupling coefficient (kp) and thickness coupling coefficient (kt)of 0.97NKN-0.03BNKT ceramics were 1483, 32% and 31%, respectively.
Abstract: Aiming at security problem of metal structure of overhead traveling crane, the accident tree is established based on Accident Tree Analysis to further study. The solution of minimizing cut sets and least path sets are obtained by accident tree calculating. Finally several possible measures to prevent structural faults are obtained through final results of the calculation analysis.
Abstract: Thermo-responsive shape-memory polymer (SMP) has been experimentally demonstrated that shape recovery can be induced by plasticizing solvent. Subject to being immersed into solvent, deformed SMP recover from the temporary shape to original shape, leading to shape recovery induced by the molecular interaction. The actuation of styrene-based SMP has been carried out by electrostatic dipole-dipole interaction and physical swelling effect, respectively. The model can be used to predict the effect of prestress, strain, volume change and chemical potential on SMP actuation in the solvent. Finally, it is found that the simulation agrees well with experimental results. The authors show that the chemo-mechanical instability occurs when the Hessian of the free-energy function ceases to the positive definite. Their calculations show that the shape recovery behavior of SMP is driven by the entropy change markedly, agreeing with existing experimental observations.
Abstract: To achieve photorealistic special effect for the industry of virtual reality, this paper proposed a real-time smoke simulation technique using particle system. Firstly, the component of particle system is discussed according to the requirement of virtual reality. Secondly, a stable scheme is employed to solve the physical equation regulating the behavior of smoke, which is modeled by the particle system. Thirdly, the object-oriented program scheme of particle system is presented in detail. Experiment results show the robustness and feasibility of the proposed technique.
Abstract: According to the practical situation (loaded by the second time), nine pieces of prestressed concrete hollow slabs which had been reinforced with CFRP were experimented on. And symmetric load was putted on the three-point of the hollow slabs. In this paper, the effects of different pasting methods and quantity of CFRP on mechanical performance and reinforcement effect of prestressed concrete hollow slabs which were damaged in varying degrees were studied. And the ultimate bearing capacity, failure mode, types of cracks and load-deformation curves of test specimen after being reinforced was analyzed systematically. After contrasting and analyzing the trial value of prestressed concrete hollow slabs, a simple, economic and reasonable reinforcing program was obtained.
Abstract: In order to improve the efficiency of automated warehouse system, the integrated scheduling problem was studied on the basis of a typical warehouse layout. A new multi-objective mathematical model was built with constraints. The reason that leads to automated guided vehicle (AGV) deadlock was analyzed on basis of bidirectional route of AGV. And a deadlock-free control policy named alternative path was proposed. A heuristic algorithm based on genetic algorithm was proposed to solve the problem. The rule of coding, selection, crossover and mutation was described in detail. The simulation result shows that the proposed algorithm is effective and can be used in practical.
Abstract: In this paper, we investigated timeslot allocation scheme in medium access control protocol for cognitive satellite networks. The timeslots for satellite primary users were allocated according to the reserve channel with priority fit algorithm and the timeslots for cognitive users were allocated according to the prediction algorithm. Compared to random allocation scheme, the correction ratio of timeslot allocation using the prediction algorithm was improved. The proposed timeslot allocation scheme adopted the combined backoff algorithm to avoid collisions. And then the improved throughput and the reduced delay could be obtained. Simulation results verify the effectiveness of the proposed timeslot allocation scheme.