SIMULATION

Yuan, Yuan; Zhao, Zhiwen; Zhang, Tianhong

doi: 10.1177/0037549719873969pmid: N/A

In the hardware-in-the-loop (HIL) simulation of the fuel control unit (FCU) for aero-engines, the back pressure has a great impact on the metered fuel, thus influencing the confidence of the simulation. During the practical working process of an aero-engine, the back pressure of the FCU is influenced by the combined effect of the pressure of the combustion chamber, the resistance of the spray nozzles, and the resistance of the distribution valve. There is a need to study the the mimicking technique of FCU back pressure. This paper models the fuel system of an aero-engine so as to reveal the impact of FCU back pressure on the metered fuel and come up with a scheme to calculate the equivalent FCU back pressure. After analyzing the requirements for mimicking the pressure, an automatic regulating facility is designed to adjust the FCU back pressure in real time. Finally, experiments are carried out to verify its performance. Results show that the mimicking technique of back pressure is well suited for application in HIL simulation. It is able to increase the confidence of the simulation and provide guidance to the implementation of mimicking the FCU back pressure.

Shang, Jianping; Wang, Wenyuan; Peng, Yun; Tian, Qi; Tang, Ying; Guo, Zijian

doi: 10.1177/0037549719875224pmid: N/A

The study of waterway through capacity for ports is a challenging problem due to the randomness and complexity of the waterway system, which needs to be analyzed by simulation technology. This paper quantitatively studies the influence of special ships on waterway through capacity and provides corresponding measures to improve waterway through capacity. The complex waterway system in the Port of Meizhou Bay is employed as a case study. Considering the actual conditions in the Port of Meizhou Bay, including the ships, berths, waterways, and natural conditions, a Simio-based simulation model is established. The real operation data from the Port of Meizhou Bay in 2015 are used to verify the correctness and effectiveness of the model. The simulation results show that special ships reduce the waterway through capacity by 4.9% and suggest that circumnavigation strategies that can be adopted after the extension and new construction of waterway systems can improve the waterway through capacity by 5.9%.

Szczęch, Marcin

doi: 10.1177/0037549719885168pmid: N/A

Magnetic fluid seals are among the most common ferrofluid applications. One interesting area is the use of numerical simulations to determine the critical pressure, which is a basic parameter determining the possible range of seal operating pressures. The purpose of this study is to present the method of critical pressure calculations in magnetic fluid seals based on magnetic field numerical simulations, which will provide better results than the methods used previously. It is a relatively simple method and can help to reduce the difference between simulations and experiments. Different seal stage shapes, such as symmetric trapezoidal, asymmetric trapezoidal, and rectangular, were taken into account. The research shows that an increase in the magnetic fluid volume applied at the seal stage and a magnetic saturation increase in the seal gap allow the manufacturing inaccuracy influence to be reduced, meaning that the difference between the simulation and experiment results is smaller. In addition, in this paper, the pressure transfer mechanism between liquid rings of the multistage seal is analyzed to show its influence on the critical pressure value calculated based on simulations.

Wang, Zhijie; Peng, Xia; Han, Fang; Song, Guangxiao

doi: 10.1177/0037549720903804pmid: N/A

The traditional clock-driven algorithm is very time-consuming when performed on large-scale neuronal networks due to the huge number of synaptic currents computation and low performance of the parallel implementation of the algorithm. We find in this paper that the conductance coefficients of all the synapses coming from the same presynaptic neuron (neuron i for example) does not need to be computed one by one, rather only one common conductance coefficient needs to be computed for all synapses from this neuron. We then propose an idea of virtual synapse for neuron i to compute this common conductance coefficient and thereby have N (N is the number of neurons in the network) virtual synapses for all presynaptic neurons in the network. Since each common conductance depends on only the spiking activity of the presynaptic neuron i and is irrelevant of postsynaptic neurons, the computation of the different virtual synapses can be deployed to different computer processing unit efficiently. By introducing a circular data structure for the virtual synapses, we present a novel parallel clock-driven algorithm based on graphics processors for simulation of neuronal networks. It is demonstrated by test results that the proposed algorithm reduces memory and time consumption greatly, and improves the performance of the parallelization for large-scale neuronal network simulations effectively.

doi: 10.1177/0037549720904262pmid: N/A