Journal of Wind Engineering and Industrial Aerodynamics最新文献

{"title":"Large scale response of a vehicle wake to on-road perturbations","authors":"Agostino Cembalo ,&nbsp;Jacques Borée ,&nbsp;Patrick Coirault ,&nbsp;Clément Dumand","doi":"10.1016/j.jweia.2024.105933","DOIUrl":"10.1016/j.jweia.2024.105933","url":null,"abstract":"<div><div>Under disturbed upstream conditions, numerous wind tunnel studies have shown that the near wake region of a vehicle loses its average symmetry, resulting in an increase of drag. The aim of this research work is to analyze the large scale response of a vehicle wake to on-road perturbations by using an instrumented vehicle and by comparing scale one wind tunnel tests, track trials and on road experiments. More precisely, in all these tests, we focus on the analysis of the asymmetry of the pressure distribution at the base. Proper Orthogonal Decomposition (POD) is used. For all cases considered, POD analysis reveals two dominant modes, respectively associated with vertical and horizontal wake large scale reorganization. More than 50% of the total energy is carried by these two modes and this value increases significantly for on-road tests. Noteworthy, the low-frequency energy content of the temporal coefficients of these modes is significantly higher on-road. Low frequencies (even very low ones) then play a major role, corresponding to a quasi-static perturbation domain of the velocity seen by the vehicle. We show that a quasi-steady exploration of the on-road yaw angle statistical distribution during a wind tunnel test captures phenomena similar to those observed on the road and is therefore interesting to evaluate on-road aerodynamic performances. This also opens perspectives for developing closed loop control strategies aiming to maintain a prescribed wake balance in order to reduce drag experienced on the road.</div></div>","PeriodicalId":54752,"journal":{"name":"Journal of Wind Engineering and Industrial Aerodynamics","volume":"255 ","pages":"Article 105933"},"PeriodicalIF":4.2,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660008","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Time-domain state-space model formulation of motion-induced aerodynamic forces on bridge decks","authors":"Simian Lei ,&nbsp;Luca Patruno ,&nbsp;Claudio Mannini ,&nbsp;Stefano de Miranda ,&nbsp;Yaojun Ge","doi":"10.1016/j.jweia.2024.105937","DOIUrl":"10.1016/j.jweia.2024.105937","url":null,"abstract":"<div><div>Motion-induced aerodynamic forces play a fundamental role in the stability and buffeting analysis of long-span bridges, which are traditionally performed in the frequency domain adopting the well-known approach based on flutter derivatives and aerodynamic admittance functions. However, the increase in span of newly designed bridges currently raises concerns regarding the role of nonlinear aerodynamic effects, the response to non-stationary winds and the aerodynamic coupling in multi-modal vibrations. Addressing these issues requires to calculate aerodynamic forces induced by arbitrary motions and, possibly, consider large variations in the incoming flow orientation, a task better suited for time-domain approaches. In this study, we introduce a time-domain state-space model formulation for motion-induced aerodynamic forces, which systematizes and generalizes previous models, while keeping a simple structure and ease of calibration. We tailor the model formulation to allow for a clear distinction between quasi-static and purely transient aerodynamic contributions and investigate the relations between the proposed model and other available models, highlighting their common underlying framework. The model is finally calibrated for a selection of bridge decks, showing a very good ability to reproduce motion-induced aerodynamic forces.</div></div>","PeriodicalId":54752,"journal":{"name":"Journal of Wind Engineering and Industrial Aerodynamics","volume":"255 ","pages":"Article 105937"},"PeriodicalIF":4.2,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660005","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mechanism of vortex-induced vibration in two lock-in regions for truss girder sections","authors":"Congjie Shang ,&nbsp;Huoyue Xiang ,&nbsp;Yulong Bao ,&nbsp;Yongle Li ,&nbsp;Kou Luo","doi":"10.1016/j.jweia.2024.105946","DOIUrl":"10.1016/j.jweia.2024.105946","url":null,"abstract":"<div><div>The long-span bridge has a flexible structure and low damping. And the truss girder section is relatively blunt, which is prone to vortex-induced vibration(VIV). Initially, the wind tunnel tests are carried out at two scales to test the two lock-in regions of VIV for the truss girder. Then, the fluid-structure coupling analysis numerical model of the simplified two-dimensional(2-D) section of the truss girder is established, and the analysis results are compared with the experiment. Finally, the time-frequency characteristics of the aerodynamic lift and the wind speed at the movable monitoring points, further the meso-mechanism of the vortex evolution in two lock-in regions are analyzed. The results indicate that there are both twice key changes in the lift frequency components during the whole process of VIV in the two lock-in regions with the increase in amplitude, which are related to the change in flow pattern. VIV in the first lock-in region is self-excited by the coupling of the wake vortex of the bridge deck and the motion of the model. VIV in the second lock-in of VIV is self-excited by the impinging shear layer instability at the leading edge of the bridge deck and the motion of the model.</div></div>","PeriodicalId":54752,"journal":{"name":"Journal of Wind Engineering and Industrial Aerodynamics","volume":"255 ","pages":"Article 105946"},"PeriodicalIF":4.2,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Similarity solution for sectional A2∗ aerodynamic derivative for single axis solar trackers at various angles of attack and ground distances","authors":"Juan A. Cárdenas-Rondón ,&nbsp;Omar Gómez-Ortega ,&nbsp;Carlos Rodríguez-Casado ,&nbsp;Mikel Ogueta-Gutiérrez ,&nbsp;Sebastián Franchini","doi":"10.1016/j.jweia.2024.105932","DOIUrl":"10.1016/j.jweia.2024.105932","url":null,"abstract":"<div><div>Based on the experimental data of the aerodynamic derivative <span><math><msubsup><mrow><mi>A</mi></mrow><mrow><mn>2</mn></mrow><mrow><mo>∗</mo></mrow></msubsup></math></span> presented in the literature, evidence was found that supports the existence of a similarity solution between <span><math><msubsup><mrow><mi>A</mi></mrow><mrow><mn>2</mn></mrow><mrow><mo>∗</mo></mrow></msubsup></math></span>, the effective mean angle of attack, <span><math><msubsup><mrow><mi>α</mi></mrow><mrow><mi>m</mi><mi>e</mi><mi>a</mi><mi>n</mi></mrow><mrow><mi>e</mi><mi>f</mi><mi>f</mi></mrow></msubsup></math></span>, the tracker height-to-width ratio, <span><math><mrow><mi>H</mi><mo>/</mo><mi>B</mi></mrow></math></span>, and the reduced velocity. <span><math><msub><mrow><mi>U</mi></mrow><mrow><mi>r</mi></mrow></msub></math></span>. With this similarity solution, it is possible to estimate <span><math><msubsup><mrow><mi>A</mi></mrow><mrow><mn>2</mn></mrow><mrow><mo>∗</mo></mrow></msubsup></math></span> for any <span><math><mrow><msubsup><mrow><mi>α</mi></mrow><mrow><mi>m</mi><mi>e</mi><mi>a</mi><mi>n</mi></mrow><mrow><mi>e</mi><mi>f</mi><mi>f</mi></mrow></msubsup><mo>∈</mo><mfenced><mrow><mo>−</mo><mn>40</mn><mo>°</mo><mo>,</mo><mo>+</mo><mn>40</mn><mo>°</mo></mrow></mfenced></mrow></math></span> and <span><math><mrow><mi>H</mi><mo>/</mo><mi>B</mi><mo>∈</mo><mfenced><mrow><mn>0</mn><mo>.</mo><mn>3</mn><mo>,</mo><mn>2</mn><mo>.</mo><mn>0</mn></mrow></mfenced></mrow></math></span> with a significantly reduced amount of experimental data. This represents a notable advancement compared to the current state of the art, as it could allow for a more detailed analysis of aeroelastic instability in flat solar trackers with fewer experimental requirements. This article presents the developed formulation and the process followed to obtain the discovered similarity solution. Relying on the similarity solution, a simplified model of <span><math><msubsup><mrow><mi>A</mi></mrow><mrow><mn>2</mn></mrow><mrow><mo>∗</mo></mrow></msubsup></math></span> has been proposed as a function of the reduced velocity and <span><math><mrow><mi>H</mi><mo>/</mo><mi>B</mi></mrow></math></span> for <span><math><mrow><msubsup><mrow><mi>α</mi></mrow><mrow><mi>m</mi><mi>e</mi><mi>a</mi><mi>n</mi></mrow><mrow><mi>e</mi><mi>f</mi><mi>f</mi></mrow></msubsup><mo>=</mo><mn>0</mn><mo>°</mo></mrow></math></span>.</div></div>","PeriodicalId":54752,"journal":{"name":"Journal of Wind Engineering and Industrial Aerodynamics","volume":"255 ","pages":"Article 105932"},"PeriodicalIF":4.2,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660458","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Machine-learning-based tropical cyclone wind field model incorporating multiple meteorological parameters","authors":"Miaomiao Wei ,&nbsp;Genshen Fang ,&nbsp;Nikolaos Nikitas ,&nbsp;Yaojun Ge","doi":"10.1016/j.jweia.2024.105936","DOIUrl":"10.1016/j.jweia.2024.105936","url":null,"abstract":"<div><div>Multiple hazards caused by tropical cyclones (TCs), such as heavy rains and strong winds, result in substantial property losses and casualties worldwide each year. TC wind field models, describing the development of the wind hazard, are key within early warning realizations and associated risk assessments. Different to conventional parametric, analytical or meteorological numerical models, this study aims to develop a machine-learning-based approach for modeling TC wind fields by incorporating multiple meteorological parameters. The wind field model considers linear and nonlinear modeling respectively, where the input data includes various meteorological parameters such as surface pressure gradient (SPG), geopotential (GEO), boundary layer height (BLH), and forecast surface roughness (FSR). The output data is the TC wind field data of the Regional and Mesoscale Meteorology Branch (RAMMB) extracted by image recognition method, and assimilated with the wind field from the fifth generation of the European Center for Medium-Range Weather Forecasts (ECMWF) atmospheric reanalysis dataset ERA5. In the linear model, various combinations of parameters are considered, yet always yielding unsatisfactory results. The best results in the linear model were obtained using all four parameter combinations, where the root mean square error (RMSE) was 2.60 m/s and the coefficient of determination <span><math><mrow><msup><mi>R</mi><mn>2</mn></msup></mrow></math></span> value was 0.44. To increase performance, three nonlinear machine learning methods—Fully Connected Deep Neural Networks (FC-DNN), Convolutional Neural Networks (CNN), and Transformer—are introduced to the training process. Comparing the wind field continuity, RMSE and <span><math><mrow><msup><mi>R</mi><mn>2</mn></msup></mrow></math></span> between the three models, it is found that the Transformer outperforms all other models, with <span><math><mrow><msup><mi>R</mi><mn>2</mn></msup></mrow></math></span> value of 0.877 and an RMSE of 2.23. As a final step, the trained Transformer model was used to predict the evolution of wind speed of the Typhoon Lekima (1909), in what could serve as effective model validation.</div></div>","PeriodicalId":54752,"journal":{"name":"Journal of Wind Engineering and Industrial Aerodynamics","volume":"255 ","pages":"Article 105936"},"PeriodicalIF":4.2,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142578652","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reconstruction of downburst wind fields using physics-informed neural network","authors":"Binbin Yao ,&nbsp;Zhisong Wang ,&nbsp;Zhiyuan Fang ,&nbsp;Zhengliang Li","doi":"10.1016/j.jweia.2024.105935","DOIUrl":"10.1016/j.jweia.2024.105935","url":null,"abstract":"<div><div>Downbursts, as a strong localized wind event, have caused significant damage to engineering structures throughout the world. However, given the spatial and temporal randomness of such strong winds, on-site measurements are often difficult to obtain a sufficient amount of valid wind field information in a short period of time. To refine the resolution of the wind field, this study proposes a physics-informed neural network network-based (PINN-based) approach to reconstruct the downburst from limited observed data. The Navier-Stokes (N-S) equations are embedded into the fully connected neural network as a physical constraint to construct the PINN. The PINN model is then validated by the reconstruction of numerical downburst generated by large eddy simulations. The reconstruction of the sparse downburst wind field by PINN performs well in both interpolation and extrapolation prediction. The optimal construction of the PINN has been evaluated through parameter analysis of the influence of training data and network parameters. Finally, the optimal PINN construction is used to reconstruct the wind field of the experimental data with a relative error of 5% for the horizontal wind velocity.</div></div>","PeriodicalId":54752,"journal":{"name":"Journal of Wind Engineering and Industrial Aerodynamics","volume":"254 ","pages":"Article 105935"},"PeriodicalIF":4.2,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142538414","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study on joint design method of multiple wind parameters for long-span bridges in deep-cutting gorge areas based on field measurement","authors":"Jinxiang Zhang ,&nbsp;Fanying Jiang ,&nbsp;Mingjin Zhang ,&nbsp;Haoxiang Zheng ,&nbsp;Yongle Li ,&nbsp;Junsong Liang","doi":"10.1016/j.jweia.2024.105930","DOIUrl":"10.1016/j.jweia.2024.105930","url":null,"abstract":"<div><div>The univariate design method may not match the wind resistance demands of bridges in mountainous areas. Therefore, it is crucial to comprehensively consider the joint effect of multiple wind parameters for determining wind-resistant design parameters of bridges. To address challenges such as short measurement periods and difficulties in expanding the extreme value model of wind parameters, a Bootstrap resampling strategy incorporating seasonal wind speed trends was developed, verified, and applied to long-term probabilistic modeling; thus, the uncertainty of the probability model of average wind parameters was investigated. Then, taking the environmental contour of wind speed and attack angle under varying wind directions as the basis, a technical framework for wind-resistant bridges based on multi-parameter joint design is proposed. Meanwhile, the main girder's longitudinal and lateral design wind speeds are derived under the joint influence of attack angle and yaw angle. The results show that the control wind direction of longitudinal and lateral design wind speed is different. The joint design considering multiple wind parameters effectively makes up the limitations of traditional methods. It provides valuable insights for wind-resistant design and lifecycle toughness evaluation of bridges in mountainous areas.</div></div>","PeriodicalId":54752,"journal":{"name":"Journal of Wind Engineering and Industrial Aerodynamics","volume":"254 ","pages":"Article 105930"},"PeriodicalIF":4.2,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142538413","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An aerodynamic model for 6-DOF flight motion of windborne debris of square plates","authors":"Lizhi Wen ,&nbsp;Kazuyoshi Nishijima","doi":"10.1016/j.jweia.2024.105929","DOIUrl":"10.1016/j.jweia.2024.105929","url":null,"abstract":"<div><div>Plate-type debris is a typical type of windborne debris, often originating from roof tiles and shingles. Numerical simulation using aerodynamic models provides a practical method to predict trajectories of windborne debris. In this paper, we first propose a revised model for the 3-degree-of-freedom (3-DOF) flight motion of square plates in winds by integrating experimental data from previous studies. Thereby, we divide the aerodynamic force and moment into a translational part and a rotational part. In addition, we propose conditions of autorotation in the revised model. The calculation of the rotational force and moment depends on whether these conditions are fulfilled. The revised model is validated by comparing the numerical results with experimental results of plate trajectories. Next, based on the revised model for the 3-DOF motion, we propose an aerodynamic model for the 6-DOF motion by incorporating the findings about the rotational force and moment, which were obtained from the authors’ previous study on the 6-DOF motion of square plates. Based on these findings, the model is developed in the way that the direction of the rotational force depends on the relative wind velocity and the angular velocity of plate, and the direction of the rotational moment depends on the translational moment. By doing so the proposed model in this paper avoids directly using a database of aerodynamics, which is large and difficult to obtain. Validation using the experimental results of plate trajectories shows that the proposed model, which has a relatively simple form, performs generally well.</div></div>","PeriodicalId":54752,"journal":{"name":"Journal of Wind Engineering and Industrial Aerodynamics","volume":"254 ","pages":"Article 105929"},"PeriodicalIF":4.2,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142538412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Large eddy simulation of the flow around a high-rise building with special focus on the two-points two-times second order statistics of the velocity field","authors":"Mohanad Elagamy ,&nbsp;Nishchay Tiwari ,&nbsp;Cristobal Gallego-Castillo ,&nbsp;Alvaro Cuerva-Tejero ,&nbsp;Oscar Lopez-Garcia ,&nbsp;Sergio Avila-Sanchez","doi":"10.1016/j.jweia.2024.105914","DOIUrl":"10.1016/j.jweia.2024.105914","url":null,"abstract":"<div><div>Comprehending the wind characteristics in urban environments is crucial to ensure optimal performance and structural integrity of wind turbines operating in urban areas. This study aims to provide a deeper insight into wind characteristics over high-rise buildings rooftop. The impact of a high-rise building configuration on the turbulent wind field characteristics is analyzed, by means of large eddy simulations of a reference wind tunnel experiment. Special attention is paid to the analysis of the second order statistics of the turbulent velocity components, as they are crucial inputs for generating synthetic urban wind fields for wind turbine aeroelastic simulations. A Spectral Representation Method is applied to generate the desired turbulent inflow represented in the experiment study. The correspondence between the predicted statistics and the experimental values of the velocity components over the rooftop reinforces the idea about the practical viability of large eddy simulation to provide atmospheric turbulence information in the urban environment required to characterize the behavior of wind systems operating in that environment. Additionally, the two-points two-times second order statistics are significantly affected by the presence of the high-rise building, especially when those statistics involve at least a point within the recirculation bubble region.</div></div>","PeriodicalId":54752,"journal":{"name":"Journal of Wind Engineering and Industrial Aerodynamics","volume":"254 ","pages":"Article 105914"},"PeriodicalIF":4.2,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142534108","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterizing surface pressure and wind fields of typhoons approaching Hong Kong","authors":"Feng Hu ,&nbsp;Junyi He ,&nbsp;Zhifei Liu ,&nbsp;Qiusheng Li ,&nbsp;Pak-Wai Chan","doi":"10.1016/j.jweia.2024.105934","DOIUrl":"10.1016/j.jweia.2024.105934","url":null,"abstract":"<div><div>In this paper, 17 severe typhoons that have affected Hong Kong are simulated using an advanced numerical atmospheric simulation system - Weather Research and Forecasting model (WRF). The simulated surface pressure and wind fields of these typhoons are validated against a wide range of field observations. Then azimuth-dependent models for the radius of maximum winds and the Holland parameter are established statistically at the surface level. It is observed that the shape parameter of the Holland pressure model is smaller at the surface than that at the gradient level. And the Holland wind field model cannot well reproduce the simulated radial wind profiles due to the complexities of nonuniform surface conditions and typhoon dynamics. It is found that the modified Rankine model provides satisfactory estimates of typhoon wind speeds in Hong Kong. Additionally, wind field asymmetries of typhoons approaching Hong Kong are highly correlated with the typhoon track velocity, vertical wind shear and the angle between them. The proposed statistical models and identified characteristics of wind field asymmetries of typhoons will provide useful information for rapidly assessing typhoon wind hazards.</div></div>","PeriodicalId":54752,"journal":{"name":"Journal of Wind Engineering and Industrial Aerodynamics","volume":"254 ","pages":"Article 105934"},"PeriodicalIF":4.2,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142534109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}