The paper presents the detailed design and benchmarking measurements for a transient linear cascade test facility with a bypass line. The test facility includes an experiment measurements line, a linear test section cascade, a bypass line and an exhaust line, and the quasi-steady-state aerodynamic and transient thermodynamic measurements can be conducted in this test facility. The linear cascade holds up 6 equally spaced cascade profiles, forming 5 completed cascade passages, and the center passage is used for aerodynamic and thermodynamic experiment measurements. Up to 2.4 kg/s of air is continuously supplied by four compressors, thus the quasi-steady-state aerodynamic test can be conducted. For a transient thermodynamic test, the mainstream is heated by a 150 kW heater and discharged to the atmosphere through a bypass line. After reaching the steady state, the bypass flow can be turned to enter the test line within 1.5 s by a control system. A significant step change of mainstream temperature is achieved in this way. A wide range of geometries and flow conditions investigations can be performed in this test facility, due to the special design of the pitch adjustment section and rotatable platform. An optical access window installed on the turntable can provide instrumentation access for Infrared (IR) measurements, laser-based measurements and visualization measurements. The benchmarking measurements at various exit Mach number (Ma) and incidence angles (β), are used to verify the aerodynamic and thermodynamic measurements performance of this transient test facility. Results show that the desired aerodynamic behaviors and a significantly transient step change (less than 1 s) of mainstream temperature are observed during the benchmark test duration. The long-time quasi-steady-state aerodynamic and transient thermodynamic measurements can be reliably conducted in this transient test facility.
Beveloid gears are usually employed to transfer motion of small shaft angle, but the assembly errors or misalignment can affect the gear tooth contact and dynamic performance. A dynamic model and tooth contact analysis model of the intersecting beveloid gear pair are established, the defects of the theoretical tooth surface in the meshing are analyzed, and a microgeometry modification method to improve the meshing performance is proposed. At the same time, the effects of system misalignment and manufacturing errors on its meshing characteristics are considered. By studying the sensitivity of the static and dynamic characteristics of beveloid gear on different misalignment components, the influence laws of misalignment on the contact pattern, transmission error, mesh stiffness, and dynamic excitation force are obtained, which give suggestions for tooth surface modification and support structural stiffness design of beveloid gear with a good NVH performance.
With the quick development of service-oriented network, the services of streaming media and their traffic has become a rather important part in the circumstance of virtual network. However, there hasn't been a unified control mechanism to maintain the qualities of these services. The QoS of streaming media is a great concern of current network, and it'll be vital in future network because of the rapid growth of internet users and traffics. This paper describes a mechanism of maintaining the survivability of streaming media service in the circumstance of overlay network. We propose a method to calculate the health value of each path and service. Through this mechanism we can evaluate the current quality of services and provide information for further decisions. As a proof of concept we implement an experimental scenario to assess the functionality and the availability of this mechanism. It has managed effectively in the evaluation of streaming services.
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