Transactions of Nanjing University of Aeronautics & Astronautics
Issue 4,2010 Table of Contents
2010(4).
Abstract:
Buildup panels for the commercial aircraft fuselage subjected to the axial com pression load are studied by both experimental and theoretical methods. An integ ral panel is designed with the same overall size and weight as the buildup str ucture, and finite element models (FEMs) of these two panels are established. Ex perimental results of buildup panels agree well with the FEM results with the nonliearity and the large deformation, so FEMs are validated. FEM calculation results of these two panels indicate that the failure mode of the i ntegral panel is different from that of the buildup panel, and the failure loa d increases by 184％ up to postbuckling. Furthermore, the integral structure is optimized by using the multiisland genetic algorithm and the sequential quadratic progr amming. Compared with the initial design, the optimal weight is reduced by 87 ％ and the strength is unchanged.
Buildup panels for the commercial aircraft fuselage subjected to the axial com pression load are studied by both experimental and theoretical methods. An integ ral panel is designed with the same overall size and weight as the buildup str ucture, and finite element models (FEMs) of these two panels are established. Ex perimental results of buildup panels agree well with the FEM results with the nonliearity and the large deformation, so FEMs are validated. FEM calculation results of these two panels indicate that the failure mode of the i ntegral panel is different from that of the buildup panel, and the failure loa d increases by 184％ up to postbuckling. Furthermore, the integral structure is optimized by using the multiisland genetic algorithm and the sequential quadratic progr amming. Compared with the initial design, the optimal weight is reduced by 87 ％ and the strength is unchanged.
2010(4).
Abstract:
Microturbine engine has no enough space for measuring impeller chara cteristics, so the design and the construction of a new test facility of micro tu rbomachinery are presented for microcentrifugal compressors and radial turb ine s. The facility is used for the full speed compressor test and the long duration hot turbine test. To rapidly adjust the testing condition, all regulations of t he opera ting state are automatically completed by the control system. The facility is al so used for testing the impeller performance with a series of diameter from 55 m m t o 180 mm as a result of the modular design. A thermal protection system is desig ned to avoid the heat distortion caused by the high turbine inlet temperature ov er 1 100 K and provide a proper experimental environment for the electronic comp onents. A pho toelectric torque transducer with the accuracy of 1％ is designed to measure the torque of rigid shaft at a high speed of 125 000 r／min. The designing techniq ues for microturbomachineries are verified by the impeller testing of the f acility.
Microturbine engine has no enough space for measuring impeller chara cteristics, so the design and the construction of a new test facility of micro tu rbomachinery are presented for microcentrifugal compressors and radial turb ine s. The facility is used for the full speed compressor test and the long duration hot turbine test. To rapidly adjust the testing condition, all regulations of t he opera ting state are automatically completed by the control system. The facility is al so used for testing the impeller performance with a series of diameter from 55 m m t o 180 mm as a result of the modular design. A thermal protection system is desig ned to avoid the heat distortion caused by the high turbine inlet temperature ov er 1 100 K and provide a proper experimental environment for the electronic comp onents. A pho toelectric torque transducer with the accuracy of 1％ is designed to measure the torque of rigid shaft at a high speed of 125 000 r／min. The designing techniq ues for microturbomachineries are verified by the impeller testing of the f acility.
2010(4).
Abstract:
Beam stiffness degrades with its age in service and its service performanc e is weakened. According to the fundamental characteristics of the reinforced co ncre te, the influence of stiffness degradation caused by different kinds of damage i s obtained. Among them, the crack is the most direct and obvious factor. Further more, according to the analysis of bending rigidity formula presented in current stan dard, an influence parameter of crack development on the stiffness degradation, i.e., nonuniformity coefficient of tensile steel strain φ, is extracted. Av erage crack distance and crack depth are taken as crack statistic parameters. Based o n analysis and modeling with ANSYS, the modified bending rigidity formula relate d to crack is obtained.
Beam stiffness degrades with its age in service and its service performanc e is weakened. According to the fundamental characteristics of the reinforced co ncre te, the influence of stiffness degradation caused by different kinds of damage i s obtained. Among them, the crack is the most direct and obvious factor. Further more, according to the analysis of bending rigidity formula presented in current stan dard, an influence parameter of crack development on the stiffness degradation, i.e., nonuniformity coefficient of tensile steel strain φ, is extracted. Av erage crack distance and crack depth are taken as crack statistic parameters. Based o n analysis and modeling with ANSYS, the modified bending rigidity formula relate d to crack is obtained.
2010(4).
Abstract:
The influence of glycol, the main composition of the most frequently used aircraft dicer, on the freezethaw durability of high performance concrete (HPC ) is investigated. Freezethaw durability of HPC is tested by accelerated freez e thaw test. Four kinds of the solution, i.e., tap water, 35％ NaCl solution, glyc ol solutions, and a LBRA type commercial aircraft deicer are employed. Results s how that freezethaw durability of HPC exposed to glycol solutions is closely related to the solution concentrations. The failure of HPC exposed to 35％ gl ycol solution is similar to that of those exposed to 35％ NaCl solution, i.e., serious surface scaling. While the damage of HPC exposed to 125％—2 5％ glycol solutions is postponed. Compared with glycol solution, the commercia l aircraft deicer has much more negative effects on HPC freezethaw durability compared with 35％ NaCl solution. In t he presence of com mercial aircraft deicer for HPC subjected to freezethaw cycles, the deteriora tion is mainly due to scaling and spalling.
The influence of glycol, the main composition of the most frequently used aircraft dicer, on the freezethaw durability of high performance concrete (HPC ) is investigated. Freezethaw durability of HPC is tested by accelerated freez e thaw test. Four kinds of the solution, i.e., tap water, 35％ NaCl solution, glyc ol solutions, and a LBRA type commercial aircraft deicer are employed. Results s how that freezethaw durability of HPC exposed to glycol solutions is closely related to the solution concentrations. The failure of HPC exposed to 35％ gl ycol solution is similar to that of those exposed to 35％ NaCl solution, i.e., serious surface scaling. While the damage of HPC exposed to 125％—2 5％ glycol solutions is postponed. Compared with glycol solution, the commercia l aircraft deicer has much more negative effects on HPC freezethaw durability compared with 35％ NaCl solution. In t he presence of com mercial aircraft deicer for HPC subjected to freezethaw cycles, the deteriora tion is mainly due to scaling and spalling.
2010(4).
Abstract:
A new orbit transfer method is presented by combining the genetic algorit h m (GA) with the refined Qlaw method. Considering the energy consumptio n , the relative thrust efficiency is introduced as a threshold deciding whether t o thrust or coast. GA is used to achieve the global timeoptimal orbit trans f er. The trajectory optimization problem is transformed into the constraint para met er optimization problem, thus the nonlinear twopoint boundary value problem is avoided. The refined Qlaw method integrated with the fuzzy logic control is adopte d for t he end course, the vibration is avoided and the high precision is achieved. The numerical simulation of satellite orbit transfer is implemented. Result s show that the new method can achieve the timeoptimal orbit transfer and t he low energy consumption, thus improving the transfer precision.
A new orbit transfer method is presented by combining the genetic algorit h m (GA) with the refined Qlaw method. Considering the energy consumptio n , the relative thrust efficiency is introduced as a threshold deciding whether t o thrust or coast. GA is used to achieve the global timeoptimal orbit trans f er. The trajectory optimization problem is transformed into the constraint para met er optimization problem, thus the nonlinear twopoint boundary value problem is avoided. The refined Qlaw method integrated with the fuzzy logic control is adopte d for t he end course, the vibration is avoided and the high precision is achieved. The numerical simulation of satellite orbit transfer is implemented. Result s show that the new method can achieve the timeoptimal orbit transfer and t he low energy consumption, thus improving the transfer precision.
2010(4).
Abstract:
A realtime tracking system for the fast moving object on the complex backgroun d is proposed. The Markov random filed (MRF) model based background subtraction algorithm is used to detect the changing pixels and track the moving object. The prior probability of the segmentation mask is modeled by using MRF, and the object tracking task is translated into the maximum aposterior (MA P) problem. Experimental results show that the method is efficient at both offli ne and online moving objects on simple and complex background.
A realtime tracking system for the fast moving object on the complex backgroun d is proposed. The Markov random filed (MRF) model based background subtraction algorithm is used to detect the changing pixels and track the moving object. The prior probability of the segmentation mask is modeled by using MRF, and the object tracking task is translated into the maximum aposterior (MA P) problem. Experimental results show that the method is efficient at both offli ne and online moving objects on simple and complex background.
2010(4).
Abstract:
The network on chip (NoC) is used as a solution for the communication p roblems in a complex system on chip (SoC) design. To further enhance performance s, the NoC architectures, a high level modeling and an evaluat ion method based on OPNET are proposed to analyze their performances on differ ent injectio n rates and traffic patterns. Simulation results for general NoC in terms of the average latency and the throughput are analyzed and used as a guideline to make appropriate choices for a given application. Finally, a MPEG4 decoder is mapped on different NoC architectures. Results prove the effectiveness of the evalua tion method.
The network on chip (NoC) is used as a solution for the communication p roblems in a complex system on chip (SoC) design. To further enhance performance s, the NoC architectures, a high level modeling and an evaluat ion method based on OPNET are proposed to analyze their performances on differ ent injectio n rates and traffic patterns. Simulation results for general NoC in terms of the average latency and the throughput are analyzed and used as a guideline to make appropriate choices for a given application. Finally, a MPEG4 decoder is mapped on different NoC architectures. Results prove the effectiveness of the evalua tion method.
2010(4).
Abstract:
A fast implementation of the convolution backprojection (CBP) algorithm in spotl ight synthetic aperture radar (SAR) is presented based on the fast Fourier transform(FFT). Traditionally, the computation of the ′backprojection′ process is expensive, since resampling in t he process is implemented by using the interpolation operation. By analyzing the relative location relationship among different pixels, the algorithm realizes the ′backprojection′ using a series of FFTs instead of the interpola tion operation. The po int target simulation validates that the new algorithm acce lerates the CBP algorithm, and the computational rate increases about 85％.
A fast implementation of the convolution backprojection (CBP) algorithm in spotl ight synthetic aperture radar (SAR) is presented based on the fast Fourier transform(FFT). Traditionally, the computation of the ′backprojection′ process is expensive, since resampling in t he process is implemented by using the interpolation operation. By analyzing the relative location relationship among different pixels, the algorithm realizes the ′backprojection′ using a series of FFTs instead of the interpola tion operation. The po int target simulation validates that the new algorithm acce lerates the CBP algorithm, and the computational rate increases about 85％.
2010(4).
Abstract:
The effect of inhaled nanoTiO2 on lung histology and serum biochemic al indexes is evaluated in healthy and adult Kunming mice (eight in each group) after exposure to TiO2 aerosols (1 500 mg／m3) in a sealed chamber. Ano ther e ight mice are exposed to indoor air to be served as a control group. Lung tissue and blood are collected after euthanizing the animals. The results show that la c tate dehydrogenase (LDH) activity increases in all experimental groups. Alanine aminotransferase(ALT) activity and blood urea nitrogen (BUN) levels are increase d in the group exposed to TiO2 aerosols for 28 d, and creatinine(Cr) level s are increased in 14 d and 28 d samples (P<005). No obvious changes are observed in other serum indexes. Lungs of mice exposed to 28 d exposure show significant but moderate increase in pulmonary inflammatio n, and many TiO2 particles are found in the interstitium of pulmonary alve oli.
The effect of inhaled nanoTiO2 on lung histology and serum biochemic al indexes is evaluated in healthy and adult Kunming mice (eight in each group) after exposure to TiO2 aerosols (1 500 mg／m3) in a sealed chamber. Ano ther e ight mice are exposed to indoor air to be served as a control group. Lung tissue and blood are collected after euthanizing the animals. The results show that la c tate dehydrogenase (LDH) activity increases in all experimental groups. Alanine aminotransferase(ALT) activity and blood urea nitrogen (BUN) levels are increase d in the group exposed to TiO2 aerosols for 28 d, and creatinine(Cr) level s are increased in 14 d and 28 d samples (P<005). No obvious changes are observed in other serum indexes. Lungs of mice exposed to 28 d exposure show significant but moderate increase in pulmonary inflammatio n, and many TiO2 particles are found in the interstitium of pulmonary alve oli.
2010(4).
Abstract:
A claylike conductive material comprising polyaniline (PANI)acetylen e black particles is fabricated as a hole conductor for dye sensitiz ed solar cell (DSSC). The results show that the introduction of acetylene black into the polymer electrolyte improves the photovoltaic behavior of solidstate DSSC, owing to the increase of the hole mobility of PANI electroly t e, the improvement of the wetting quality of the composite electrolyte, and the reinforcement of interface contact between electrode and the electrolyte. Final ly, the overall energy conversion efficiency of DSSC with PANI50％(in weight) a cetylene black electrolyte is 48％ of that of liquid DSSC. Therefore, the PANI a cetylene black composition is a credible alternative to hole conductor in ap plication of solid DSSC.
A claylike conductive material comprising polyaniline (PANI)acetylen e black particles is fabricated as a hole conductor for dye sensitiz ed solar cell (DSSC). The results show that the introduction of acetylene black into the polymer electrolyte improves the photovoltaic behavior of solidstate DSSC, owing to the increase of the hole mobility of PANI electroly t e, the improvement of the wetting quality of the composite electrolyte, and the reinforcement of interface contact between electrode and the electrolyte. Final ly, the overall energy conversion efficiency of DSSC with PANI50％(in weight) a cetylene black electrolyte is 48％ of that of liquid DSSC. Therefore, the PANI a cetylene black composition is a credible alternative to hole conductor in ap plication of solid DSSC.
2010(4).
Abstract:
The gel polymer electrolytes(GPEs) based on poly (vinylidence fluoride)(PVDF)／a crylate interpenetrating polymer network(IPN) are prepared. The microphase separation type GPEs are characterized by Fourier transform infrared(FTIR) spectroscopy, scanning electron microscope(SEM), respectively. Moreover, the conductivity and the vo ltagecurrent curves of the electrolytes are measured by electrochemical works t ation. The higher porosity and electrolyte uptake are observed in the membranes prepared at lower crosslinker concentration. The suitable crosslinking a crylate monomer improves the porosity and the electrochemical beha vior of GPE. A dyesensitized solar cell(DSSC) employing PGE based on PVDF／pol y(ethylene glycol dimethacrylate) (PEGDMA) IPN yields an opencircuit voltage of 0674 V, shortcircuit current of 8476 mA·cm-2〖ＫＧ４〗and the con version efficiency of 2710％ under 100 mW·cm－２〖ＫＧ４〗illuminatio n.
The gel polymer electrolytes(GPEs) based on poly (vinylidence fluoride)(PVDF)／a crylate interpenetrating polymer network(IPN) are prepared. The microphase separation type GPEs are characterized by Fourier transform infrared(FTIR) spectroscopy, scanning electron microscope(SEM), respectively. Moreover, the conductivity and the vo ltagecurrent curves of the electrolytes are measured by electrochemical works t ation. The higher porosity and electrolyte uptake are observed in the membranes prepared at lower crosslinker concentration. The suitable crosslinking a crylate monomer improves the porosity and the electrochemical beha vior of GPE. A dyesensitized solar cell(DSSC) employing PGE based on PVDF／pol y(ethylene glycol dimethacrylate) (PEGDMA) IPN yields an opencircuit voltage of 0674 V, shortcircuit current of 8476 mA·cm-2〖ＫＧ４〗and the con version efficiency of 2710％ under 100 mW·cm－２〖ＫＧ４〗illuminatio n.
2010(4).
Abstract:
To solve aircraft arrival sequencing and scheduling problems, and imp rove the typical predatory search algorithm(PSA), an innovative PSA is developed . The new PSA uses variable constraints of local search and global search to avo id falling into local optimal solutions and the degeneration of solutions. To te st t he performance of new PSA, a case study with ten arriving flights and two runway s is performed. Test results show that the new PSA performs much better than typ ical PSA and genetic algorithm(GA) in the aspects of the rate of gaining optimal solutions and the computational time.
To solve aircraft arrival sequencing and scheduling problems, and imp rove the typical predatory search algorithm(PSA), an innovative PSA is developed . The new PSA uses variable constraints of local search and global search to avo id falling into local optimal solutions and the degeneration of solutions. To te st t he performance of new PSA, a case study with ten arriving flights and two runway s is performed. Test results show that the new PSA performs much better than typ ical PSA and genetic algorithm(GA) in the aspects of the rate of gaining optimal solutions and the computational time.
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