Transactions of Nanjing University of Aeronautics and Astronautics最新文献

{"title":"A 60 GHz phased array system analysis and Its phase shifter in a 40 nm CMOS technology","authors":"Hao Gao, Kuangyuan Ying, P. Baltus","doi":"10.16356/J.1005-1120.2019.04.003","DOIUrl":"https://doi.org/10.16356/J.1005-1120.2019.04.003","url":null,"abstract":"A 60 GHz phased array system for mm-wave frequency in 5 G is introduced and a 5 bit digitally controlled phase shifter in 40 nm CMOS technology is presented. In a phased array system,the signal to noise ratio(SNR)of the receiver is improved with the beaming forming function. Therefore,the communication data rate and distance are improved accordingly. The phase shifter is the key component for achieving the beam forming function,and its resolution and power consumption are also very critical. In the second half of this paper,an analysis of phase shifter is introduced,and a 60 GHz 5 bit digitally controlled phase shifter in 40 nm complementary metal oxide semiconductor(CMOS)technology is presented. In this presented phase shifter,a hybrid structure is implemented for its advantage on lower phase deviation while keeping comparable loss. Meanwhile,this digitally controlled phase shifter is much more compact than other works. For all 32 states,the minimum phase error is 1.5°,and the maximum phase error is 6.8°. The measured insertion loss is-20.9±1 d B including pad loss at 60 GHz and the return loss is more than 10 d B over 57—64 GHz. The total chip size is 0.24 mm2 with 0 m W DC power consumption.","PeriodicalId":39730,"journal":{"name":"Transactions of Nanjing University of Aeronautics and Astronautics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45251926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Simulation Tools for a Fiber-Optic Based Structural Health Monitoring System","authors":"A. Güemes, A. Fernández-López, J. García-Ramírez, M. Reyes-Perez, Flor Criado Zurita","doi":"10.16356/j.1005-1120.2018.02.219","DOIUrl":"https://doi.org/10.16356/j.1005-1120.2018.02.219","url":null,"abstract":"Probability of detection (POD) graphics allow for a change from qualitative to quantitative assessment for every damage detection system, and as such it is a main request for conventional non-destructive testing (NDT) techniques. Its availability can greatly help towards the industrialization of the corresponding Structural health monitoring (SHM) system. But having in mind that for SHM systems the sensors are at fixed positions, and the location of a potential damage would change its detectability. Consequently robust simulation tools are required to obtain the model assisted probability of detection (MAPOD) which is needed to validate the SHM system. This tool may also help for the optimization of the sensor distribution, and finally will allow a probabilistic risk management. INDEUS, simulation of ultrasonic waves SHM system, was a main milestone in this direction. This article deals with the simulation tools for a strain based SHM system, using fiber optic sensors (FOS). FOS are essentially strain/temperature sensors, either with multi-point or with distributed sensing. The simulation tool includes the finite element model (FEM) for the original and damaged structure, and algorithms to compare the strain data at the pre-established sensors locations, and from this comparison to extract information about damage occurrence and location. \u0000 The study has been applied to the structure of an all-composite unmanned aircraft vehicle (UAV) now under construction, designed at Universidad Politecnica de Madrid for the inspection of electrical utilities networks. Distributed sensing optical fibers were internally bonded at the fuselage and wing. Routine inspection is planned to be done with the aircraft at the test bench by imposing known loads. From the acquired strain data, damage occurrence may be calculated as slight deviations from the baselines. This is a fast inspection procedure without requiring trained specialists, and it would allow for detection of hidden damages. Simulation indicates that stringer partial debondings are detected before they become critical, while small delaminations as those produced by barely visible impact damages would require a prohibited number of sensing lines. These simulation tools may easily be applied to any other complex structure, just by changing the FEM models. From these results it is shown how a fiber optic based SHM system may be used as a reliable damage detection procedure.","PeriodicalId":39730,"journal":{"name":"Transactions of Nanjing University of Aeronautics and Astronautics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44878085","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Adhesion Property of Vertically Aligned Carbon Nanotubes Under High Temperature","authors":"Guo Feiqian, Li Yang, Meng Guiyun, Sun Chengxiang, Dai Zhendong","doi":"10.16356/J.1005-1120.2018.S.041","DOIUrl":"https://doi.org/10.16356/J.1005-1120.2018.S.041","url":null,"abstract":"Because of having millions of well vertically aligned hairs on their feet, geckos can fluently walk on the vertical walls and even ceilings. Vertically aligned carbon nanotube (VACNT) array has been widely used as a bio-mimetic adhesive due to the structural and functional similarity with gecko's foot hairs. Besides, the advanced properties of VACNT make it a prominent functional adhesive. In this paper, the dry adhesion of VACNT array under the temperature range of 25-150℃ is studied. Because of the intrinsic excellent thermal resistance, VACNT array shows great adhesion under high temperature. When the temperature changes from 25℃ to 150℃, the shear adhesive strength of VACNT array deceases from 12.04 N/cm2 to 6.08 N/cm2. Though there is a 50 percent decrease, the adhesive strength of 6.08 N/cm2 is still remarkable for dry adhesive materials. The VACNT's micro structures are analyzed by SEM and the adhesion change phenomenon is interpreted in theory. We believe that the robust high temperature adaptation of VACNT dry adhesive can be used in many extreme environments, such as aerospace application.","PeriodicalId":39730,"journal":{"name":"Transactions of Nanjing University of Aeronautics and Astronautics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45712534","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modeling Method and Control Strategy for Hose-Drogue Aerial Refueling System","authors":"Wu Ling, Sun Yongrong, Huang Bin, Liu Jianye","doi":"10.16356/j.1005-1120.2018.02.371","DOIUrl":"https://doi.org/10.16356/j.1005-1120.2018.02.371","url":null,"abstract":"Conventional method for hose-drogue model of aerial refueling system is known to be complex due to the flexible body of hose. And as reported, drogues are unstable in atmospheric turbulence, which greatly decreases docking success rates. This paper proposes a dynamic model for a hose-drogue aerial refueling system based on Kane equation and rigid multi-body dynamics, and analyzes its performance. Furthermore, the nonlinear dynamic model is linearized at the equilibrium point and simplified from full order to 2nd order. Based on the simplified 2nd order model, active control strategies, including proportion integral derivative(PID) and liner quadratic regulator(LQR) control laws, are designed to inhibit the pendulum movement of drogue due to, atmospheric turbulences. Numerical simulation results show the significant correctness of the proposed dynamic model by steady-state drag and balance position of drogue when the tanker flights under different conditions. Moreover, the steady state position error varies within 1 cm, thanks to either controller, when the drogue suffers from moderate-level atmospheric turbulences. Further, the PID controller exhibits better control effect and higher control precision than LQR controller.","PeriodicalId":39730,"journal":{"name":"Transactions of Nanjing University of Aeronautics and Astronautics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47988851","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Segmentation of Thermographic Sequences in Frequency Modulated Thermal Wave Imaging for NDE of GFRP","authors":"K. Murali, D. K. Reddy","doi":"10.16356/J.1005-1120.2018.02.226","DOIUrl":"https://doi.org/10.16356/J.1005-1120.2018.02.226","url":null,"abstract":"Image processing techniques have become highly essential to improve the data usefulness of the raw images obtained for infrared non-destructive evaluation (NDE). The identification of defective regions from a thermogram has been a common problem in the field of NDE. Image segmentation is one of the promising approaches to identify defective regions from thermogram. In the present work, segmentation approach based on clustering is employed. In this image patterns are organized into clusters or groups considering the relationship among these. The method involves finding the centroids of the regions and formation of clusters around each centroid. Thresholding is applied to improve accuracy in formation of clusters. Double thresholding method is adapted to retrieve the shape of defect and to improve the possible diagnosis capabilities of system for NDE applications. The proposed method is investigated with frequency modulated thermal wave imaging (FMTWI) over glass fiber reinforced polymers (GFRP). The GFRP sample consists of square shaped Teflon inserts of different dimensions placed at various depths. A comparative study of the proposed novel segmentation scheme and existing segmentation methods is conducted.","PeriodicalId":39730,"journal":{"name":"Transactions of Nanjing University of Aeronautics and Astronautics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47879023","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Compressive Sensing Sparse Sampling Method for Composite Material Based on Principal Component Analysis","authors":"Su Yajie, Gu Feihong, Ji Sai, W. Lihua","doi":"10.16356/J.1005-1120.2018.02.282","DOIUrl":"https://doi.org/10.16356/J.1005-1120.2018.02.282","url":null,"abstract":"Signals can be sampled by compressive sensing theory with a much less rate than those by traditional Nyquist sampling theorem, and reconstructed with high probability, only when signals are sparse in the time domain or a transform domain. Most signals are not sparse in real world, but can be expressed in sparse form by some kind of sparse transformation. Commonly used sparse transformations will lose some information, because their transform bases are generally fixed. In this paper, we use principal component analysis for data reduction, and select new variable with low dimension and linearly correlated to the original variable, instead of the original variable with high dimension, thus the useful data of the original signals can be included in the sparse signals after dimensionality reduction with maximize portability. Therefore, the loss of data can be reduced as much as possible, and the efficiency of signal reconstruction can be improved. Finally, the composite material plate is used for the experimental verification. The experimental result shows that the sparse representation of signals based on principal component analysis can reduce signal distortion and improve signal reconstruction efficiency.","PeriodicalId":39730,"journal":{"name":"Transactions of Nanjing University of Aeronautics and Astronautics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45481909","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rotor Airload and Acoustics Prediction Based on CFD/CSD Coupling Method","authors":"wang liangquan, X. Guohua, Shi Yongjie","doi":"10.16356/J.1005-1120.2018.02.343","DOIUrl":"https://doi.org/10.16356/J.1005-1120.2018.02.343","url":null,"abstract":"An advanced airload and noise prediction method based on computational fluid dynamics/computational structural dynamics (CFD/CSD) coupling for helicopter rotor has been developed in this paper. In the present method, Navier-Stokes equation is applied as the governing equation, and a moving overset grid system is generated in order to account for the blade motions in rotation, flapping and pitching. The blade structural analysis is based on 14-DOF Euler beam model, and the finite element discretization is conducted on Hamilton's variational principle and moderate deflection theory. Aerodynamic noise is calculated by Farassat 1A formula derived from FW-H equation. Using the developed method, numerical example of UH-60A is performed for aeroelastic loads calculation in a low-speed forward flight, and the calculated results are compared with both those from isolated CFD method and available experimental data. Then, rotor noise is emphatically calculated by CFD/CSD coupling method and compared with the isolated CFD method. The results show that the aerodynamic loads calculated from CFD/CSD method are more satisfactory than those from isolated CFD method, and the exclusion of blade structural deformation in rotor noise calculation may cause inaccurate results in low-speed forward flight state.","PeriodicalId":39730,"journal":{"name":"Transactions of Nanjing University of Aeronautics and Astronautics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47565098","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Non-destructive Evaluation of Absolute Stress in Steel Members Using Shear-Wave Spectroscopy","authors":"Li Diankun, He Jingbo, Li Zuohua, Teng Jun","doi":"10.16356/J.1005-1120.2018.02.236","DOIUrl":"https://doi.org/10.16356/J.1005-1120.2018.02.236","url":null,"abstract":"Non-destructive measurement of absolute stress in steel members can provide useful information to optimize the design of steel structures and allow the safety of existing structures to be evaluated. This paper investigates the non-destructive capability of ultrasonic shear-wave spectroscopy in absolute stress evaluation of steel members. The effect of steel-member stress on the shear-wave amplitude spectrum is investigated, and a method of absolute stress measurement is proposed. Specifically, the process for evaluating absolute stress using shear-wave spectroscopy is summarized. Two steel members are employed to investigate the relationship between the stress and the frequency in shear-wave echo amplitude spectrum. The H-beam loaded by the universal testing machine is evaluated by the proposed method and the traditional strain gauge method for verification. The results show that the proposed method is effective and accurate for determining absolute stress in steel members.","PeriodicalId":39730,"journal":{"name":"Transactions of Nanjing University of Aeronautics and Astronautics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44479342","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Full Wavefield Analysis for Damage Assessment in Composite Materials","authors":"T. Wandowski, P. Malinowski, W. Ostachowicz","doi":"10.16356/J.1005-1120.2018.02.264","DOIUrl":"https://doi.org/10.16356/J.1005-1120.2018.02.264","url":null,"abstract":"In this paper damage assessment based on guided elastic wave propagation phenomenon is presented. Guided waves are generated by piezoelectric transducer and registered by scanning laser doppler vibrometer (SLDV). Signal processing is based on the analysis of full wavefield measurements gathered from dense mesh of measurement points spanned over area of investigated samples. Full wavefield measurement approach allows creation of animations presenting the guided wave propagation in the structure. Moreover such approach is suitable for analysis of interaction of guided waves with discontinuities located in structure. In the research attention is paid especially on analysis of phenomenon of S0/A0' guided wave mode conversion due to interaction with investigated discontinuities-teflon inserts and impact damage. The presented work is related to glass fibre reinforced polymer (GFRP) samples. In the research, auxiliary non-destructive testing (NDT) method is also utilized. The aim of this method is to indicate the depth of discontinuity, and to prove that delamination was created in the case of impact damage. Auxiliary method is based on terahertz spectroscopy (THz) where the analysis of propagation of electromagnetic waves in the terahertz band is conducted. THz spectroscopy method can be utilized for damage assessment in the dielectric materials like GFRP.","PeriodicalId":39730,"journal":{"name":"Transactions of Nanjing University of Aeronautics and Astronautics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44576092","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical Study of Parachute-Payload Land Site Distribution with Randomize Wind Gust Model","authors":"Tang Jianhua, Qian Linfang, Yin Qiang, Jiang Li","doi":"10.16356/j.1005-1120.2018.02.383","DOIUrl":"https://doi.org/10.16356/j.1005-1120.2018.02.383","url":null,"abstract":"A parachute-payload model with randomize wind gust is developed to study the landing accuracy of the parachute decelerator system, which can be exactly described by the landing site distribution. The research focuses on the steady descent phase of the parachute descent process, so the parachute and the payload suspension formulation during the phase are mainly discussed. In addition, since the wind effects have a significant impact on the land site distribution of the passive decelerator system and it is difficult to obtain the exact wind profile in practice, major features of parachute-payload system are studied via the randomized wind gust formulation. As the randomized wind gust formulation is adopted, the wind effect can be considered without the exact wind gust profile and the parachute aerodynamic simulation can be fulfilled with uncertainties.Finally, the model is validated and discussed, and the parachute land site distributions with different wind randomize profiles are presented for comparison. The results show that when parachute is less stable, the land site tends to have a larger variance.","PeriodicalId":39730,"journal":{"name":"Transactions of Nanjing University of Aeronautics and Astronautics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43725770","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}