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Inconel 718 superalloys deposited by laser solid forming (LSF) were heat treated with solution treatment, intermediate heat treatment (IHT) and two-stage aging treatment in sequence (SITA heat treatment). The effect of IHT temperature on microstructure, tensile property and notch sensitivity of LSFed Inconel 718 superalloy at 500 ℃ were investigated. As-deposited columnar grains have transformed to equiaxed grains and the grains were refi ned due to the recrystallization during the SITA heat treatment. It is found that the size and amount of δ phase dispersed at grain boundaries decreased with the increasing of IHT temperature, and δ phase disappeared when the IHT temperature reached 1 020 ℃. The ultimate tensile strength (UTS) and yield strength (YS) of smooth samples increased to a maximum when the IHT temperature reached 980 ℃ and then decreased slightly to a minimum when the IHT temperature was 1 000 ℃, and followed by slight increasing again till the IHT temperature reached 1 020 ℃, resulted from the competition of precipitation strengthening effect of γ″ and γ′ phase and the grain boundary weakening effect caused by the gradual disappearance of δ phase with increasing the IHT temperature. The notch sensitivity factor (q e ) decreased but still greater than 1 as the IHT temperature increased, which is attributed to the decrease of the size and amount of δ precipitation.

The enhanced X-ray Timing and Polarimetry Observatory (eXTP) is a flagship international collaboration mission led by Chinese Academy of Sciences, with a large contribution from more than 20 European institutes. eXTP mission is designed to study the equation of state of ultra-dense matter under extreme conditions of strong density, gravity and magnetic field. The satellite carries four main instruments, including the Spectroscopy Focusing Array (SFA), the Large Area Detector (LAD), the Polarimetry Focusing array (PFA) and the Wide Field Monitor (WFM), enabling simultaneous spectral-timing-polarimetry studies of celestial sources in the energy range from 0.5-30 keV. The satellite will fly at a near-zero-inclination Low Earth Orbit, and is featured with long-time steady high-precision coaxial pointing, near realtime burst alert distribution, and follow-up maneuver capabilities. This paper describes the primary mission requirements and constraints, and presents an overall mission analysis including orbit analysis, pointing strategy, and board-ground communications, etc. The preliminary design of eXTP satellite is also introduced, including satellite overall configuration, observation modes, avionics architecture and development plan.

This paper presents an immersive virtual reality environment (IVE) for performing assembly and maintenance simulations using the Jack ® software package. The Flock of Birds™ motion tracking system is used to capture body postures of an immersed human and reproduce it in real-time in the virtual environment. The Cyberglove™ is used to capture finger movements in realtime for realistic grasp interaction. A comprehensive set of voice commands has been developed to provide significant functionality to allow one person to control the virtual environment while immersed in the environment, thereby improving productivity. One of the most important applications is a method by which the immersed human can walk and fly through the virtual environment, thereby greatly expanding the envelope of the virtual environment navigable under the constraints imposed by the limited tracking volume. These capabilities have been used to investigate assembly simulation of the windshield deicer of a Cessna aircraft.