Hu Q.,Commercial Aircraft Corporation of China |
Zhang A.,University of British Columbia |
Zhang A.,Shanghai JiaoTong University
Journal of Air Transport Management | Year: 2015
This paper demonstrates that aircraft acquisition by airlines may contain a portfolio of real options (flexible strategies) embedded in the investment's life cycle, and that if airlines rely solely on the static NPV method, they are likely to underestimate the true investment value. Two real options are investigated: i) the "shutdown-restart" option (a carrier may shutdown a plane if revenues are less than costs, but restarts it if revenues are more than costs), and ii) the option to defer aircraft delivery. We quantify the values of these options in a case study of a major U.S. airline. The economic insight could help explain observed capital expenditures of airlines, and serve as a rule of thumb in evaluating capital budgeting decisions. A compound option (consisting of both the shutdown-restart and defer options) is also analyzed. © 2015 Elsevier Ltd.
Zhang D.-N.,Shanghai Normal University |
Shangguan Q.-Q.,Shanghai Normal University |
Xie C.-J.,Commercial Aircraft Corporation of China |
Liu F.,Shanghai Aircraft Design and Research Institute
Journal of Alloys and Compounds | Year: 2014
The dynamic mechanical behaviors of 7075-T6 aluminum alloy at various strain rates were measured by dynamic tensile tests using the electronic universal testing machine, high velocity testing system and split Hopkinson tensile bar (SHTB). Stress-strain curves at different rates were obtained. The results show that the strain rate hardening effect of 7075-T6 aluminum alloy is significant. By modifying the strain rate hardening term in the Johnson-Cook constitutive model, a new Johnson-Cook (JC) constitutive model of 7075-T6 aluminum alloy was obtained. The improved Johnson-Cook model matched the experiment results very well. With the Johnson-Cook constitutive model, numerical simulations of tensile tests at different rates for 7075-T6 aluminum alloy were conducted. According to tensile loading and stress-strain relation of 7075-T6 aluminum alloy, calculation results were compared with experimental results. Accuracy of the modified Johnson-Cook constitutive equation was further proved. © 2014 Elsevier B.V. All rights reserved.
Shanghai Aircraft Manufacturing Co. and Commercial Aircraft Corporation Of China | Date: 2011-12-31
An apparatus for testing the air permeability in the thickness direction of a resin matrix composite material layer includes a mold having a cavity and a covering plate, a loading apparatus, a temperature controlling apparatus, a vacuuming apparatus, and a flow detecting element. An air inlet is connected to the flow detecting element, and an air outlet is connected to the vacuuming apparatus. The covering plate has a through-hole with upper and lower ventilation pieces. The loading apparatus addresses the upper ventilation piece. A test specimen is laid flat between the ventilation pieces. Employment of the present invention allows for accurate testing of air permeability of pre-impregnated material in the thickness direction of the resin matrix composite material layer under different pressure and temperature conditions.
Shanghai Aircraft Manufacturing Co Ltd and Commercial Aircraft Corporation Of China Ltd | Date: 2011-12-31
An apparatus for testing the gas permeability on the inward facing direction of a pre-impregnated resin matrix composite material layer includes a mold, a loading apparatus, a temperature control apparatus, a vacuuming apparatus, and a flow detecting element. A test specimen is laid flat inside the mold between airtight sealing elements that leave exposed two ends of the test specimen on the inward facing direction of the layer. An air inlet and an air outlet respectively are arranged on the mold and correspond to the two exposed ends of the test specimen. The inlet is connected to the flow detecting element, and the outlet is connected to the vacuuming apparatus. Air is forced to move in a vacuumed cavity along the inward facing direction of the layer. Testing of air permeability of pre-impregnated material in solidification technique is allowed via adjustments of pressure and temperature.
Huazhong University of Science, Technology and Commercial Aircraft Corporation Of China | Date: 2011-06-30
An icing detector probe includes three sections arranged sequentially along the direction of air flow, namely, a first section, a second section and a third section. The shape of the outer surface of the first section is suitable for collecting droplets in the air flow. The shape of the outer surface of the second section is suitable for full decelerating and releasing latent heat of large droplets during their movements. The outer surface of the third section is suitable for icing of large droplets. The probe detects icing by distinguishing and identify large droplets icing. The probe effectively detects types of traditional icing, thus being helpful for exact detection of icing thickness. An icing detector including said icing detector probe is also provided.