Aerospace Science and Technology最新文献

{"title":"Urban air mobility flight hazard index prediction using WRF-LES simulations and LSTM networks","authors":"Dongsu Seon ,&nbsp;Jaeguk Lee ,&nbsp;Inrae Kim ,&nbsp;Hoijo Jeong ,&nbsp;Seungkeun Kim ,&nbsp;Kyu Hong Kim ,&nbsp;Shinkyu Jeong","doi":"10.1016/j.ast.2025.110911","DOIUrl":"10.1016/j.ast.2025.110911","url":null,"abstract":"<div><div>Urban air mobility (UAM) has emerged as a potential solution to mitigate urban traffic congestion. However, severe turbulence in urban wind environments poses a significant safety issue for UAM operations. To ensure safe and reliable UAM operations, a UAM hazard prediction system is essential. This study proposes a UAM flight hazard index prediction system. To achieve this, first, UAM flight data were generated through the coupling of a UAM dynamics simulator with an actual urban wind environment. The urban wind environment was produced using the Weather Research and Forecasting-Large Eddy Simulation coupled model. By applying wingless type and lift&amp;cruise type UAM dynamics simulators to these urban wind environments, a flight simulation database was constructed. For the assessment of the UAM flight hazard, a new hazard index, <span><math><msub><mover><mi>v</mi><mo>→</mo></mover><mrow><mi>dev</mi></mrow></msub></math></span>, was derived from wind components that induce path deviations. Analyses confirmed that <span><math><msub><mover><mi>v</mi><mo>→</mo></mover><mrow><mi>dev</mi></mrow></msub></math></span> indicates wind-induced hazards while accounting for both wind magnitude and direction. Long Short-Term Memory networks were then trained using the flight simulation database to predict the hazard index. In particular, an initializer neural network was incorporated to enable predictions from arbitrary initial states. The resulting models demonstrated high accuracy for both types of UAM. Using these models, the hazard index in UAM corridors was evaluated. The results exhibited different trends in the hazard index under varying wind conditions. Under the headwind and tailwind conditions, the hazard index values were low for both types. In contrast, under crosswind conditions, the hazard index was high. The wind speed increasing with altitude was another factor contributing to the hazard index. Additionally, different hazard index values were observed between the two UAM types under the same wind conditions due to the different flight characteristics.</div></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":"168 ","pages":"Article 110911"},"PeriodicalIF":5.8,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145158254","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dynamics analysis, control and flight test of all-wing tail-sitter configuration solar powered UAV","authors":"Xin Zhao ,&nbsp;Zhou Zhou ,&nbsp;Jiayue Hu ,&nbsp;Kelei Wang ,&nbsp;Baiyang Li","doi":"10.1016/j.ast.2025.110945","DOIUrl":"10.1016/j.ast.2025.110945","url":null,"abstract":"<div><div>This paper proposes a novel all-wing tail-sitter Vertical Take-off/Landing (VTOL) solar-powered Unmanned Aerial Vehicle (UAV) configuration. It adopts thrust differential control instead of traditional aerodynamic control surfaces to maximize the solar panel layout area and the photovoltaic energy-harvesting power. Compared to conventional electric VTOL (eVTOL) aircraft, this design achieves over sixfold improvement in endurance. To address insufficient control effectiveness caused by the large wingspan and low wing loading, a variable thrust installation angle is designed. A dynamic model incorporating the propulsive-aerodynamic coupling effects between the propeller slipstream and the wing, along with the thrust installation configuration, is developed. Detailed stability and maneuverability analysis demonstrates that, the designed thrust installation angle effectively enhances roll control authority during VTOL phases and benefits longitudinal static stability in level flight, without significantly compromising dynamic stability. Aiming at the nonlinear propulsive-aerodynamic coupling and model errors, an INDI-based unified attitude control law is designed and evaluated through simulations and full-envelope flight tests, confirming the control effectiveness and configuration feasibility. Furthermore, the maximum endurance performance of the prototype is discussed based on the power data collected during flight and the numerical model of solar irradiance.</div></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":"168 ","pages":"Article 110945"},"PeriodicalIF":5.8,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145105168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thrust loss analysis of a turbine-based combined cycle nozzle","authors":"Guangtao SONG,&nbsp;Jinglei XU,&nbsp;Zheng LV","doi":"10.1016/j.ast.2025.110949","DOIUrl":"10.1016/j.ast.2025.110949","url":null,"abstract":"<div><div>In this study, a parallel turbine based combined cycle (TBCC) combined nozzle is designed and investigated. Two-dimensional computational fluid dynamics are conducted using the SST <em>k</em>-<em>ω</em> two-equation model. The basic single expansion ramp nozzle (SERN) contours at the design point are designed using a new method based on maximum thrust theory. The forces contributions from different SERN segments are statistically analyzed. Losses due to non-full and non-isentropic expansion are compared across different contours, with the cowl’s initial expansion angle set at 0.31 rad. The adjustment scheme of the combined nozzle includes a splitter to form the turbojet nozzle throat and a hydraulic cylinder to form the ramjet nozzle throat. According to the geometric relationship, the turbojet flow-path inlet height (<em>H</em>_i,tur) and the splitter length (<em>L</em>_spl) are selected as optimization parameters of this adjustment scheme. The influence of <em>H</em>_i,tur and <em>L</em>_spl on the performance trend for the same configuration under different working conditions, as well as the relative magnitude for different configurations under the same working condition are analyzed. Exit height constraint loss determines the upper limit of nozzle performance, while nozzle design loss and non-isentropic expansion loss determine the specific numerical value of nozzle performance. Analysis of geometric parameters influence on expansion process and estimation of different kinds of thrust losses can improve design efficiency, and enable nozzle performance prediction during geometric selection stage.</div></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":"168 ","pages":"Article 110949"},"PeriodicalIF":5.8,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145219726","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Integrated structural design optimization of space vehicles with multidisciplinary constraints","authors":"Pranav Borwankar ,&nbsp;Rakesh K. Kapania ,&nbsp;Daisaku Inoyama ,&nbsp;Tom Stoumbos","doi":"10.1016/j.ast.2025.110906","DOIUrl":"10.1016/j.ast.2025.110906","url":null,"abstract":"<div><div>The aerospace industry’s competitiveness in the global market relies heavily on the digital transformation of engineering design processes. Central to this transformation are Multidisciplinary Design Optimization (MDO) frameworks, which are pivotal in integrating different engineering disciplines and facilitating the optimization of complex systems. Specifically, a Multidisciplinary Structural Analysis and Design Optimization (MSADO) framework addresses interactions between structural responses. This paper introduces an MSADO framework tailored for spacecraft structures, leveraging commercial software tools and open-source Python libraries. The framework is exemplified through the simplified finite element modeling of a small spacecraft, showcasing its multidisciplinary design capabilities. Optimization is carried out for various launch vehicle and in-orbit loads, adhering to the GEVS, SMC, and MIL 810E standards. The proposed framework seamlessly integrates structural, thermal, and acoustic analyses to optimize overall spacecraft performance while adhering to multiple design constraints. The framework is applied to design a typical spacecraft structure by optimizing structural weight for required performance under varied static and dynamic loading conditions, both within the launch vehicle and in orbit. To enhance optimization performance, especially in scenarios involving composite laminates in the design, lamination parameter optimization and mixed integer programming are integrated into the framework by extending the lamination parameter formulations to facilitate multidisciplinary analysis, resulting in an <span><math><mrow><mn>84</mn><mspace></mspace><mo>%</mo></mrow></math></span> reduction in computational costs compared to direct fiber angle parameterization.</div></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":"168 ","pages":"Article 110906"},"PeriodicalIF":5.8,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145219811","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bird strike on aeroengine fan blades: a combined experimental and numerical study","authors":"Jiaxuan Sun ,&nbsp;Meng Liu ,&nbsp;Ning Li ,&nbsp;Bin Jiang ,&nbsp;Yazhou Guo","doi":"10.1016/j.ast.2025.110955","DOIUrl":"10.1016/j.ast.2025.110955","url":null,"abstract":"<div><div>Bird strike damage as a significant safety concern has been widely focused on during the service life of aeroengines. This research enhances traditional analysis methodologies to accurately predict and assess fan blade damage characteristics. Firstly, the dynamic mechanical properties of TC6 titanium alloy were determined through comprehensive material testing. Using multi-objective optimization methods, a high-precision modified Johnson-Cook constitutive model (MJC) and fracture model were developed for fan blades. Material parameters and numerical models were validated through gelatin bird impact tests on static single blades. Then, numerical simulations analyzed blade-bird cutting effects, with particular emphasis on rotation speed and bird velocity impacts. Results demonstrated that the resultant velocity deviation angle and blade twist angle significantly influence blade damage patterns. Therefore, this study presents an impact interaction mechanism that explains the counterintuitive phenomenon of increased blade damage under reduced rotation speed and bird velocity conditions. Subsequently, expressions for average impact force and root stress were derived from fundamental bird strike parameters, quantifying both impact loads and root stress concentration levels. Finally, compressor impact simulations revealed that bird fragments significantly affect stator blades positioned behind the fan blades. These findings provide valuable reference points for bird-strike resistance analysis and aeroengine fan blade design optimization.</div></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":"168 ","pages":"Article 110955"},"PeriodicalIF":5.8,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145158294","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation of inter rotor spacing effect on aerodynamics and aeroacoustics of a coaxial rigid rotor helicopters in full configuration using high-fidelity numerical simulations","authors":"Sung U Kang,&nbsp;Seung Been Shin,&nbsp;Rho Shin Myong,&nbsp;Hakjin Lee","doi":"10.1016/j.ast.2025.110959","DOIUrl":"10.1016/j.ast.2025.110959","url":null,"abstract":"<div><div>The coaxial rotor system, a key component of high-speed and long-range compound helicopters, eliminates the need for a tail rotor. However, aerodynamic interactions between the upper and lower rotors can substantially influence aerodynamic performance and noise generation. Inter-rotor spacing (IRS), defined as the ratio of the vertical distance between the upper and lower rotors to the diameter is a critical design parameter that affects rotor wake structure and blade–vortex interaction (BVI), particularly during forward flight. This study investigates the effects of IRS and advance ratio on the unsteady aerodynamics and aeroacoustics of coaxial rotors through high-fidelity numerical simulations. The simulations employ the Spalart–Allmaras improved delayed detached eddy simulation model coupled with overset mesh techniques. Aeroacoustic analysis is conducted using the Ffowcs Williams–Hawkings acoustic analogy. The full-configuration X2TD helicopter, excluding the pusher propeller, serves as the baseline model. Results indicate that a greater IRS value leads to higher thrust growth rates under low-speed forward flight conditions and reduces unsteady loading fluctuations. Moreover, a greater IRS value mitigates BVI and loading noise, reducing the overall sound pressure levels. Notably, acoustic differences between the isolated coaxial rotor and full-configuration models highlight the influence of fuselage reflection, with downward noise propagation attenuated by up to 2 dB in the latter. These findings provide valuable insights into IRS optimization for enhanced aerodynamic efficiency and noise reduction in coaxial rotorcraft.</div></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":"168 ","pages":"Article 110959"},"PeriodicalIF":5.8,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145158187","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nonlinear aerodynamic flutter responses of the composite pipes conveying two-phase flow using mathematical simulation and data-driven solution","authors":"Yujun Cao ,&nbsp;Mohammed El-Meligy ,&nbsp;Mubariz Garayev","doi":"10.1016/j.ast.2025.110947","DOIUrl":"10.1016/j.ast.2025.110947","url":null,"abstract":"<div><div>Two-phase flows are encountered in a wide range of engineering systems, including nuclear reactors, thermal power plants, chemical reactors, petroleum pipelines, refrigeration systems, and aerospace propulsion systems. The ability to model and analyze two-phase flows is essential for the design, operation, and optimization of these systems. So, in this work, for the first time, nonlinear aerodynamic responses of pipe conveying two-phase flow using data-driven solutions in the mathematical framework are presented. The presented pipe system is made of triply periodic minimum material with exceptional mechanical properties, such as high specific strength, specific stiffness, and energy absorption qualities. The distribution parameter varies as a function of the two-phase Reynolds number in a pipe while keeping the void percent constant and modifying the density ratios. Nonlinear Von-Karman theory, as well as trigonometric shear deformation theory, is presented to correctly simulate the nonlinear aerodynamic responses of the pipe reinforced by triply periodic minimum material conveying two-phase flow. After that, a numerical solution procedure is used to solve the nonlinear governing equations with the aid of nonlinear boundary equations. After obtaining the dataset using the mathematical modeling section, the data-driven solution is used to correctly test, train, and validate results for simulating the current applicable structure in other complex situations. The proposed data-driven solution provides valuable insights into the nonlinear aerodynamic responses of the reinforced pipes, facilitating the design and optimization of robust and efficient piping systems for various engineering applications.</div></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":"168 ","pages":"Article 110947"},"PeriodicalIF":5.8,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145219725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Gas ingress prediction method for high rotational mach number rim seals","authors":"Xiaozhi Kong ,&nbsp;Haocheng Shu ,&nbsp;Shuang Yang ,&nbsp;Qunjie Yang ,&nbsp;Gaowen Liu","doi":"10.1016/j.ast.2025.110957","DOIUrl":"10.1016/j.ast.2025.110957","url":null,"abstract":"<div><div>The rim seal is a key component in an aero-engine turbine used to prevent gas ingress, and its performance has a significant impact on turbine efficiency and turbine-disc lifespan. Based on high - speed compressible fluid theory, this paper derives the radial momentum equation for fluid under isentropic, inviscid, compressible conditions. It proves theoretically that increasing the cooling air's circumferential and radial velocities helps resist gas ingress. Furthermore, a high - speed compressible rim seal estimation model was developed, converting the complex gas ingress problem into a cooling air supply pressure issue. Validated by high rotational Mach number rim seal experiments, when the total pressure margin coefficient exceeds zero, the sealing efficiency remains above 0.99. Thus, the model can accurately determine whether gas ingress occurs in the rim seal structure. Moreover, further research was conducted on the critical parameters of the estimation model, specifically the supply total pressure coefficient and the total pressure loss coefficient. It was found that a higher mainstream Mach number requires a higher cooling air supply pressure coefficient. An empirical relationship was developed based on experimental data, linking the variation of the cooling air supply total pressure coefficient to the mainstream Mach number. The maximum deviation between this correlation and the experimentally measured coefficient is less than 8.9%. Moreover, the cooling air total pressure loss coefficient increases with higher mainstream and rotational Mach numbers but decreases with a higher cooling air Mach number.</div></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":"168 ","pages":"Article 110957"},"PeriodicalIF":5.8,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145158251","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A new multifunctional multi-arc enhanced cylindrical metastructure integrating stable mechanical properties, two plateau stress stages, and Poisson's ratio sign-switching","authors":"Hao Xu,&nbsp;Hai-Tao Liu","doi":"10.1016/j.ast.2025.110958","DOIUrl":"10.1016/j.ast.2025.110958","url":null,"abstract":"<div><div>The increase in energy absorption is often accompanied by an increase in stiffness, which will exacerbate structural damage under compressive load. Based on multi-arc enhanced re-entrant honeycomb, a novel multi-arc enhanced cylindrical metastructure (MAECM) is designed in this paper to solve the conflict between stiffness and energy absorption. The new metastructure exhibits two plateau stress stages, Poisson's ratio sign-switching, and constant Poisson's ratio. Specimens with different parameters are printed, and the corresponding finite element models are established. The effects of various parameters on mechanical properties are investigated by finite element analysis and experiment. Results show that the two plateau stress stages and Poisson's ratio sign-switching can be achieved through the self-contact of the connecting rods. The constant Poisson's ratio can be achieved under specific geometric parameters to achieve stable mechanical properties of the structure. The geometric parameters can effectively adjust the Young's modulus, specific energy absorption (SEA), Poisson's ratio, contact strain, and sign-switching strain of the structure. Compared with the original structure, the Young's modulus of MAECM has decreased by 67 %, and the energy absorption has increased by 164 %. The various mechanical properties, low stiffness, and superior energy absorption capacity of MAECM make it more advantageous than other proposed structures. These outstanding mechanical properties enable MAECM to solve the conflict between stiffness and energy absorption. The lower Young's modulus and adjustable Poisson's ratio enable MAECM to be used as the internal supporting substructure of the missile skin. The deformation of the MAECM can achieve the adjustment of the missile's motion attitude. MAECM expands the application of metastructures in the aerospace field and provides a novel method for designing multifunctional metastructures.</div></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":"168 ","pages":"Article 110958"},"PeriodicalIF":5.8,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145105243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of radial hot streak position on heat transfer in a reverse-flow combustor coupled with turbine guide vanes","authors":"Jian Song ,&nbsp;Lanfang Zhao ,&nbsp;Rémy Mével ,&nbsp;Zhixin Zhu ,&nbsp;Gaofeng Wang","doi":"10.1016/j.ast.2025.110953","DOIUrl":"10.1016/j.ast.2025.110953","url":null,"abstract":"<div><div>The ongoing pursuit of higher thrust-to-weight ratios in aero-engines has intensified aerodynamic and thermal coupling between combustors and turbines, especially in reverse-flow combustor configurations with compact hot-end layouts. This study presents a novel experimental and numerical investigation of hot streak dynamics and their impact on turbine guide vane (TGV) heat load. A high-fidelity test rig featuring a three-head sector reverse-flow combustor and six TGVs, combined with a dual-stage radial swirler, was developed to evaluate the circumferential and radial temperature distribution at the combustor outlet under representative conditions. Experimental measurements and computational simulations revealed that strategic adjustment of the dilution hole areas in the inner and outer liners enables precise control over the radial positioning of hot streaks. By increasing the inner liner dilution area while proportionally decreasing the outer liner dilution area—thus maintaining a constant total dilution area—the central position of the hot streak is shifted from the upper region to the midsection. This adjustment results in a peak temperature reduction of up to 6.4 % and a 15 % decrease in OTDF, effectively lowering the outlet temperature distortion factor (OTDF) and achieving a more uniform temperature distribution at the combustor exit. This modification not only lowers the temperature and static pressure on the guide vane surface but also significantly alleviates high-temperature ablation at the vane’s upper region. These findings advance understanding on combustor-turbine thermal interaction and inform optimized cooling strategies for advanced aero-engines.</div></div>","PeriodicalId":50955,"journal":{"name":"Aerospace Science and Technology","volume":"168 ","pages":"Article 110953"},"PeriodicalIF":5.8,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145093819","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}