Pub Date : 2021-06-01DOI: 10.6125/JOAAA.202106_53(2).05
W. Kuntjoro, N. Anwar, R. E. Nasir
Unmanned Aerial Vehicles (UAV) are commonly used for surveillance and aerial mapping. Balsa wood construction is common for small UAV. However, for larger UAV size, balsa construction can be too fragile. 3D printing based airframe can help in producing accurate profile contour needed in a wing design, particularly on Blended Wing Body (BWB) design. Nowadays, 3D printing machines are not expensive and easily available. Flight Technology and Test Centre (FTTC) RIG, Universiti Teknologi MARA (UiTM) has been developing and building small BWB UAV made of 3D printing. At the moment, the strength and stiffness of the wing box structure has not been properly investigated. The general target of this research is to understand the static mechanical behavior of a small wing box suitable for UAV manufactured by 3D printing. A simple wing box that can be produced on in-house 3D printer was produced. Standard tensile test was conducted to the PLA (Polylactic Acid) printed material. Finite element simulation of the wing box was performed, and static test experiment was conducted. Stresses and displacements were obtained and analyzed.
{"title":"A Study of 3D Printed Box Structure","authors":"W. Kuntjoro, N. Anwar, R. E. Nasir","doi":"10.6125/JOAAA.202106_53(2).05","DOIUrl":"https://doi.org/10.6125/JOAAA.202106_53(2).05","url":null,"abstract":"Unmanned Aerial Vehicles (UAV) are commonly used for surveillance and aerial mapping. Balsa wood construction is common for small UAV. However, for larger UAV size, balsa construction can be too fragile. 3D printing based airframe can help in producing accurate profile contour needed in a wing design, particularly on Blended Wing Body (BWB) design. Nowadays, 3D printing machines are not expensive and easily available. Flight Technology and Test Centre (FTTC) RIG, Universiti Teknologi MARA (UiTM) has been developing and building small BWB UAV made of 3D printing. At the moment, the strength and stiffness of the wing box structure has not been properly investigated. The general target of this research is to understand the static mechanical behavior of a small wing box suitable for UAV manufactured by 3D printing. A simple wing box that can be produced on in-house 3D printer was produced. Standard tensile test was conducted to the PLA (Polylactic Acid) printed material. Finite element simulation of the wing box was performed, and static test experiment was conducted. Stresses and displacements were obtained and analyzed.","PeriodicalId":335344,"journal":{"name":"Journal of aeronautics, astronautics and aviation, Series A","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133065253","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}
Pub Date : 2021-06-01DOI: 10.6125/JOAAA.202106_53(2).01
M. Z. Abidin, S. A. Rahman, I. Nursyirwan, Amiruddin Mustafa
The number of aircraft operating at Kuala Lumpur International Airport (KLIA) and at KLIA Terminal Control Area (TMA) has steadily increased over the year. It has been forecasted that by 2020, KLIA will reach a number of 63 million passengers per annum, which is more than 80% of its capacity. The aim of the study is to find a correlation between flight departure delay and air occupancy, as well as ground parameters of the departure. To achieve this, regression and correlation analysis were conducted on the traffic delay, air occupancy, runway departure and runway occupancy time. The data was acquired using Automatic Dependent Surveillance Broadcast (ADS-B) from 1/2/2019 to 28/2/2019. Based on the analysis, it was observed that the mean daily flight departure delay has a moderate positive relationship with TMA air occupancy with a correlation of r(26) = 0.550, p = 0.004. It can also be concluded that different combinations of routes used for the flight to depart, from its taxiing points to the departure runway, affects the delay of the departure. However, other parameters such as runway occupancy time and distance to runway only had a weak correlation (r lower than 0.5) towards departure delay.
{"title":"Analysis and Visualization of KLIA Flight Departure Delay Pattern","authors":"M. Z. Abidin, S. A. Rahman, I. Nursyirwan, Amiruddin Mustafa","doi":"10.6125/JOAAA.202106_53(2).01","DOIUrl":"https://doi.org/10.6125/JOAAA.202106_53(2).01","url":null,"abstract":"The number of aircraft operating at Kuala Lumpur International Airport (KLIA) and at KLIA Terminal Control Area (TMA) has steadily increased over the year. It has been forecasted that by 2020, KLIA will reach a number of 63 million passengers per annum, which is more than 80% of its capacity. The aim of the study is to find a correlation between flight departure delay and air occupancy, as well as ground parameters of the departure. To achieve this, regression and correlation analysis were conducted on the traffic delay, air occupancy, runway departure and runway occupancy time. The data was acquired using Automatic Dependent Surveillance Broadcast (ADS-B) from 1/2/2019 to 28/2/2019. Based on the analysis, it was observed that the mean daily flight departure delay has a moderate positive relationship with TMA air occupancy with a correlation of r(26) = 0.550, p = 0.004. It can also be concluded that different combinations of routes used for the flight to depart, from its taxiing points to the departure runway, affects the delay of the departure. However, other parameters such as runway occupancy time and distance to runway only had a weak correlation (r lower than 0.5) towards departure delay.","PeriodicalId":335344,"journal":{"name":"Journal of aeronautics, astronautics and aviation, Series A","volume":"72 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130015852","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}
Pub Date : 2021-06-01DOI: 10.6125/JOAAA.202106_53(2).25
M. N. Elya, M. Z. Jurij, M. R. Saad, S. Azrad
This paper presents the results of battery consumption for quadrotor flight under wind turbulence conditions. The study was performed in an open-jet wind tunnel. A motion capture system was developed at the exhaust part of the open-jet wind tunnel. The motion capture system comprised 6 optitrack cameras installed outside the exhaust part of the wind tunnel, and a PC at the ground station. A LiPo rechargeable battery was used, with two sizes, namely 5200 mAH with a discharge rate of 30 C and 4200 mAH with a discharge rate of 40 C, to evaluate the quadrotor's battery consumption and flight performance. The results show that the 4200 mAH battery performed better (with a smaller steady-state error during hovering) compared to the 5200 mAH battery. To overcome turbulence, the quadrotor propellers have to act fast, so the higher discharge rate from 4200 mAH battery gave better performance, as it kept the quadrotor hovering in close proximity to the desired setpoint.
{"title":"Evaluation of Quadrotor Flight and Battery Consumption under Wind Turbulence conditions in an Open-Jet Wind Tunnel","authors":"M. N. Elya, M. Z. Jurij, M. R. Saad, S. Azrad","doi":"10.6125/JOAAA.202106_53(2).25","DOIUrl":"https://doi.org/10.6125/JOAAA.202106_53(2).25","url":null,"abstract":"This paper presents the results of battery consumption for quadrotor flight under wind turbulence conditions. The study was performed in an open-jet wind tunnel. A motion capture system was developed at the exhaust part of the open-jet wind tunnel. The motion capture system comprised 6 optitrack cameras installed outside the exhaust part of the wind tunnel, and a PC at the ground station. A LiPo rechargeable battery was used, with two sizes, namely 5200 mAH with a discharge rate of 30 C and 4200 mAH with a discharge rate of 40 C, to evaluate the quadrotor's battery consumption and flight performance. The results show that the 4200 mAH battery performed better (with a smaller steady-state error during hovering) compared to the 5200 mAH battery. To overcome turbulence, the quadrotor propellers have to act fast, so the higher discharge rate from 4200 mAH battery gave better performance, as it kept the quadrotor hovering in close proximity to the desired setpoint.","PeriodicalId":335344,"journal":{"name":"Journal of aeronautics, astronautics and aviation, Series A","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124570678","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}
Pub Date : 2021-06-01DOI: 10.6125/JOAAA.202106_53(2).27
Baizura Bohari, Ahmad Zaim Adam Ghazali, M. R. Saad
An introduction of slipstream effects induced by the distributed propeller at low Reynolds number will lead to notable reductions in aerodynamics efficiency with significance changes of the free-stream properties of the wing. To address the issues, a set of reasonable aerodynamic design method for multiple propeller-wing integration is necessary to capture the wing aerodynamics performances behaviour at low Reynolds number. In that respect, the flow condition of a rectangular wing with NACA0012 airfoil section under the influence of the propeller slipstream was simulated and validated using low-order fidelity solver. A validation of the methods chosen found to be assuring in comparison with experimental data. The effects of various parameters were taken into account like the angle of attack, the rotational speed, the thrust and the power required. The aerodynamic aspect of the propeller-wing integration for a number of actuator disks propeller modelled distributed along the span of the wing of the aircraft is measured. The results show the role of propeller diameter and the numbers installed along the wingspan lead to a significance increase on lift performance and lift to drag ratio.
{"title":"Validation of Low Fidelity Propeller-Wing Modeling Method at Low Reynolds Number","authors":"Baizura Bohari, Ahmad Zaim Adam Ghazali, M. R. Saad","doi":"10.6125/JOAAA.202106_53(2).27","DOIUrl":"https://doi.org/10.6125/JOAAA.202106_53(2).27","url":null,"abstract":"An introduction of slipstream effects induced by the distributed propeller at low Reynolds number will lead to notable reductions in aerodynamics efficiency with significance changes of the free-stream properties of the wing. To address the issues, a set of reasonable aerodynamic design method for multiple propeller-wing integration is necessary to capture the wing aerodynamics performances behaviour at low Reynolds number. In that respect, the flow condition of a rectangular wing with NACA0012 airfoil section under the influence of the propeller slipstream was simulated and validated using low-order fidelity solver. A validation of the methods chosen found to be assuring in comparison with experimental data. The effects of various parameters were taken into account like the angle of attack, the rotational speed, the thrust and the power required. The aerodynamic aspect of the propeller-wing integration for a number of actuator disks propeller modelled distributed along the span of the wing of the aircraft is measured. The results show the role of propeller diameter and the numbers installed along the wingspan lead to a significance increase on lift performance and lift to drag ratio.","PeriodicalId":335344,"journal":{"name":"Journal of aeronautics, astronautics and aviation, Series A","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121063410","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}
Pub Date : 2021-03-01DOI: 10.6125/JOAAA.202103_53(1).05
Sarmad Daood Salman Dawood, M. Y. Harmin, A. Harithuddin, C. C. Ciang, A. Rafie
A subassembly from the structural subsystem for a conceptual microsatellite designed for earth resources missions underwent normal modes analyses, after implementing an alternative approach to mass reduction, other than implementing advanced space qualified materials. This approach involved developing and implementing a set of geometric patterns that imposed upon certain components of the structural subassembly as perforation patterns, hence achieving mass reduction through straightforward material removal. This approach was proposed to introduce a relatively low-cost and easily implemented mass reduction methodology, which can be utilized by entities with little or no infrastructure and experience in advanced materials, though aspiring to develop their own satellite developing capabilities. The subassembly was the primary load path through which the launch loads pass, the so-called central box, consisting of four Aluminum 6061 identical planar plates, fastened together by titanium fasteners. The subassembly's fundamental natural frequency and attendant mode shape, for all cases, were computed utilizing the finite element method. The current work's approach to mass reduction resulted in an approximate 20% percent reduction in mass from the unperforated case, depending upon the exact thickness value employed for the subassembly plates, hence indicating that the perforation approach is valid.
{"title":"Computational Study of Mass Reduction of a Conceptual Microsatellite Structural Subassembly Utilizing Metal Perforations","authors":"Sarmad Daood Salman Dawood, M. Y. Harmin, A. Harithuddin, C. C. Ciang, A. Rafie","doi":"10.6125/JOAAA.202103_53(1).05","DOIUrl":"https://doi.org/10.6125/JOAAA.202103_53(1).05","url":null,"abstract":"A subassembly from the structural subsystem for a conceptual microsatellite designed for earth resources missions underwent normal modes analyses, after implementing an alternative approach to mass reduction, other than implementing advanced space qualified materials. This approach involved developing and implementing a set of geometric patterns that imposed upon certain components of the structural subassembly as perforation patterns, hence achieving mass reduction through straightforward material removal. This approach was proposed to introduce a relatively low-cost and easily implemented mass reduction methodology, which can be utilized by entities with little or no infrastructure and experience in advanced materials, though aspiring to develop their own satellite developing capabilities. The subassembly was the primary load path through which the launch loads pass, the so-called central box, consisting of four Aluminum 6061 identical planar plates, fastened together by titanium fasteners. The subassembly's fundamental natural frequency and attendant mode shape, for all cases, were computed utilizing the finite element method. The current work's approach to mass reduction resulted in an approximate 20% percent reduction in mass from the unperforated case, depending upon the exact thickness value employed for the subassembly plates, hence indicating that the perforation approach is valid.","PeriodicalId":335344,"journal":{"name":"Journal of aeronautics, astronautics and aviation, Series A","volume":"122 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124184194","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}
Pub Date : 2021-03-01DOI: 10.6125/JOAAA.202103_53(1).03
Saifei Hu, Yinghong Kan, L. Hsu
{"title":"Localization Uncertainty Constrained Lateral PID Control with Aids of Fuzzy Logic Considering LiDAR NDT Matching Error","authors":"Saifei Hu, Yinghong Kan, L. Hsu","doi":"10.6125/JOAAA.202103_53(1).03","DOIUrl":"https://doi.org/10.6125/JOAAA.202103_53(1).03","url":null,"abstract":"","PeriodicalId":335344,"journal":{"name":"Journal of aeronautics, astronautics and aviation, Series A","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114923929","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}
Pub Date : 2021-03-01DOI: 10.6125/JOAAA.202103_53(1).02
S. Jheng, Shau-Shiun Jan
{"title":"Implementation of Wide Area Multilateration Using a 1090 MHz ADS-B Signal","authors":"S. Jheng, Shau-Shiun Jan","doi":"10.6125/JOAAA.202103_53(1).02","DOIUrl":"https://doi.org/10.6125/JOAAA.202103_53(1).02","url":null,"abstract":"","PeriodicalId":335344,"journal":{"name":"Journal of aeronautics, astronautics and aviation, Series A","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132450750","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}
Pub Date : 2021-01-13DOI: 10.6125/JOAAA.202106_53(2).11
S. Shahimi, N. Abdullah, M. Hrairi, M. Ahmad
This research renders a numerical investigation of whirling engine blades subjected to bird strike impact. The numerical modelling of the bird strike investigation was conducted employing SPH. The bird model was established as a gelatine material and is the geometry of the bird was anticipated. As most bird strikes transpire during take-off and landing, the bird was modelled with a set velocity of 120m/s and is impacted on the engine blades, where the damage of the blades is then assessed. The engine blades were modelled as a tetrahedron mesh for accuracy in LS-DYNA software and are rotating at 200 rad/s counter-clockwise. The engine blade material is modelled with Johnson-Cook failure constants. The results are manifested as effective stresses, which shows the structural damage of the engine blades struck by the bird, which induces deflection that significantly damages the blades. Further assessments of bird velocity and engine blade rotation variations are also presented.
{"title":"Numerical Investigation on the Damage of Whirling Engine Blades Subjected to Bird Strike Impact","authors":"S. Shahimi, N. Abdullah, M. Hrairi, M. Ahmad","doi":"10.6125/JOAAA.202106_53(2).11","DOIUrl":"https://doi.org/10.6125/JOAAA.202106_53(2).11","url":null,"abstract":"This research renders a numerical investigation of whirling engine blades subjected to bird strike impact. The numerical modelling of the bird strike investigation was conducted employing SPH. The bird model was established as a gelatine material and is the geometry of the bird was anticipated. As most bird strikes transpire during take-off and landing, the bird was modelled with a set velocity of 120m/s and is impacted on the engine blades, where the damage of the blades is then assessed. The engine blades were modelled as a tetrahedron mesh for accuracy in LS-DYNA software and are rotating at 200 rad/s counter-clockwise. The engine blade material is modelled with Johnson-Cook failure constants. The results are manifested as effective stresses, which shows the structural damage of the engine blades struck by the bird, which induces deflection that significantly damages the blades. Further assessments of bird velocity and engine blade rotation variations are also presented.","PeriodicalId":335344,"journal":{"name":"Journal of aeronautics, astronautics and aviation, Series A","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115237167","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}
Pub Date : 2020-12-01DOI: 10.6125/JOAAA.202012_52(4).05
L. Xiyu, X. Zhan, Shizhuang Wang, Y. Zhai
This paper proposes a novel cooperative navigation scheme to support multiple Unmanned Aerial Vehicle (UAV) formation flight. Comparing to standalone Global Navigation Satellite System (GNSS), the new approach takes advantage of inner communication capability among UAVs to achieve navigation information fusion. As a result, the navigation accuracy, robustness and continuity can be improved. This is of particular significance in urban environments, because the user receivers are subject to high multipath, non-line-of-sight signal reception and signal blockage. With the aid of relative sensing technologies, all the GNSS observations are firstly combined to estimate the position of a designated point (defined as virtual centroid). Then, the positions of each individual UAV are derived by fusing the position estimate of virtual centroid and the known relative positions. This method is implemented, validated, and analyzed through a series of simulations, and the results suggest significant accuracy improvement as compared to standalone GNSS approaches. Moreover, sensitivity analyses are carried out to address the impact of environmental changes on navigation performance.
{"title":"Measurement-Domain Cooperative Navigation for Multi-UAV Systems Augmented by Relative Positions","authors":"L. Xiyu, X. Zhan, Shizhuang Wang, Y. Zhai","doi":"10.6125/JOAAA.202012_52(4).05","DOIUrl":"https://doi.org/10.6125/JOAAA.202012_52(4).05","url":null,"abstract":"This paper proposes a novel cooperative navigation scheme to support multiple Unmanned Aerial Vehicle (UAV) formation flight. Comparing to standalone Global Navigation Satellite System (GNSS), the new approach takes advantage of inner communication capability among UAVs to achieve navigation information fusion. As a result, the navigation accuracy, robustness and continuity can be improved. This is of particular significance in urban environments, because the user receivers are subject to high multipath, non-line-of-sight signal reception and signal blockage. With the aid of relative sensing technologies, all the GNSS observations are firstly combined to estimate the position of a designated point (defined as virtual centroid). Then, the positions of each individual UAV are derived by fusing the position estimate of virtual centroid and the known relative positions. This method is implemented, validated, and analyzed through a series of simulations, and the results suggest significant accuracy improvement as compared to standalone GNSS approaches. Moreover, sensitivity analyses are carried out to address the impact of environmental changes on navigation performance.","PeriodicalId":335344,"journal":{"name":"Journal of aeronautics, astronautics and aviation, Series A","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114565266","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}
Pub Date : 2020-12-01DOI: 10.6125/JOAAA.202012_52(4).04
H. Wang, J. Juang
{"title":"An Improved Precise Point Positioning Method Based on Between-Satellite Single-Difference and Carrier Smoothing","authors":"H. Wang, J. Juang","doi":"10.6125/JOAAA.202012_52(4).04","DOIUrl":"https://doi.org/10.6125/JOAAA.202012_52(4).04","url":null,"abstract":"","PeriodicalId":335344,"journal":{"name":"Journal of aeronautics, astronautics and aviation, Series A","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122869038","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：