The results show that the performance of optimized fan is improved by lowering the energy loss which caused by the secondary flow vortex, the volute tongue, the wake-jet and the angle of attack.

研究结果表明：通过优化有效降低了因二次流漩涡、风机蜗舌结构、尾流-射流和正冲角等造成的能量损失，提高了离心通风机性能。

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Since the attack, Executive Jet, a company that offers part-ownership of private jets, has been deluged with calls.

ECONOMIST: Can it ever again be business as usual?

Meanwhile in Washington, the Pentagon - the heart of the US defence establishment - reopened on Wednesday, even though only half of the building is safe for use after attack by another crashing hijacked jet.

BBC: Welshman filmed early crash shots

It includes ground troops with supporting artillery, amphibious assault vehicles and light armour, plus transport and attack helicopters and perhaps AV-8B Harrier jet fighter-bombers, capable of taking off and landing vertically.

BBC: F/A-18C prepares to launch from the USS Enterprise