Lu K.,Science and Technology on Space Physics Laboratory |
Xing T.,IDC Beijing Co
International Journal of Computer Science and Applications | Year: 2016
In the era of cloud computing and big data, the demand for real-time data processing and availability poses higher requirements for network load balancing. Cognitive network has unique self-learning and re-configuration abilities that can improve the effectiveness of load balancing. Based on the existing traffic scheduling algorithms, this article will discuss the possibility of improving weighted least-connection scheduling algorithm by leveraging cognitive network. A dynamic load balancing algorithm (NNPMA,Neural Network Prediction Model Algorithm) will be developed on the basis of traffic prediction model. NNPMA can enable least load scheduling in real time for service request from node and configure available idle resources upfront to ensure compliance with QoS. This traffic scheduling algorithm will be simulated with OPNET and it will be applied to cloud computing architecture. The test results indicate that this algorithm can achieve loading performance better than the unimproved weighted least-connection scheduling algorithm without significantly increasing network overhead. © Technomathematics Research Foundation.
Shao C.,Zhejiang University |
Nie L.,Science and Technology on Space Physics Laboratory |
Chen W.,Zhejiang University
Aerospace Science and Technology | Year: 2016
Hypersonic vehicles are enveloped by a plasma sheath that affects the data transmission and object identification. This paper develops a numerical methodology based on Magnetohydrodynamics equations to study the electromagnetic environment of hypersonic vehicles under the condition of carbon-based thermal protection material ablation. A surface ablation model considering the oxidation and sublimation ablation process is coupled with a Navier-Stokes solver by a gas-solid interaction method to simulate the ablation plasma flows. A piecewise linear current density recursive convolution finite-difference time-domain method is applied to further analyze the interaction between the incident electromagnetic wave and the plasma sheath. The computational results for an HTV-2 type vehicle indicate that both ablation and non-ablation plasma sheaths have significant effects on the electromagnetic environment of the vehicle. Compared with a non-ablation plasma sheath, ablation results in a decrease in the number of electrons and increases the number of neutral particles and therefore changes characteristic parameters of the plasma. Details of the electromagnetic scattering characteristics are reported to highlight the influences of ablation on the reflectivity, penetrability, and absorptivity of the plasma sheath for incident electromagnetic waves over different bands. © 2016 Elsevier Masson SAS.
Cao L.,Shanghai JiaoTong University |
Liu W.-C.,Shanghai JiaoTong University |
Li Z.-Q.,Shanghai Aviation Precision Machinery Research Institute |
Wu G.-H.,Shanghai JiaoTong University |
And 3 more authors.
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2014
The microstructure, mechanical properties and fracture behavior of sand-cast Mg-10Gd-3Y-0.5Zr alloy (mass fraction, %) under T6 condition (air cooling after solid solution and then aging heat treatment) were investigated. The optimum T6 heat treatments for sand-cast Mg-10Gd-3Y-0.5Zr alloy are (525 °C, 12 h + 225 °C, 14 h) and (525 °C, 12 h + 250 °C, 12 h) according to age hardening curve and mechanical properties, respectively. The ultimate tensile strength, yield strength and elongation of the Mg-10Gd-3Y-0.5Zr alloy treated by the two optimum T6 processes are 339.9 MPa, 251.6 MPa, 1.5% and 359.6 MPa, 247.3 MPa, 2.7%, respectively. The tensile fracture mode of peak-aged Mg-10Gd-3Y-0.5Zr alloy is transgranular quasi-cleavage fracture. © 2014 The Nonferrous Metals Society of China.
Wang Y.,Science and Technology on Space Physics Laboratory
Proceedings - 8th International Conference on Internet Computing for Science and Engineering, ICICSE 2015 | Year: 2015
This paper analyzes the ablation in a liquid rocket combustion chamber's high altitude simulation tests. Based on the characteristic of combustion chamber and the history of the malfunction, our proposed corrective measure of the chamber and relevant product reliability validation tests were conducted. The validation tests showed that our corrective measure is feasible and relevant reliability met our requirements. The investigation of purchased products should start during the phases of product manufacturing, especially for the design of combustion chamber cooling. © 2015 IEEE.
Liu W.,Shanghai JiaoTong University |
Jiang L.,Shanghai JiaoTong University |
Cao L.,Shanghai JiaoTong University |
Mei J.,Shanghai JiaoTong University |
And 5 more authors.
Materials and Design | Year: 2014
In this study, the tensile properties, high cycle fatigue behavior and plane-strain fracture toughness of the sand-cast Mg-10Gd-3Y-0.5Zr magnesium alloy were investigated, comparison to that of sand-cast plus T6 heat treated magnesium alloy which named after sand-cast-T6. The results showed that the tensile properties of the sand-cast alloy are greatly improved after T6 heat treatment, and the fatigue strength (at 107cycles) of the sand-cast Mg-10Gd-3Y-0.5Zr magnesium alloy increases from 95 to 120MPa after T6 heat treatment, i.e. the improvement of 26% in fatigue strength has been achieved. The plane-strain fracture toughnesses KIC of the sand-cast and sand-cast-T6 alloys are about 12.1 and 16.3MPam1/2, respectively. In addition, crack initiation, crack propagation and fracture behavior of the studied alloys after tensile test, high cycle fatigue test and plane-strain fracture toughness test were also investigated systematically. © 2014 Elsevier Ltd.