EUREKA: Physics and Engineering最新文献

{"title":"Design and simulation of automotive radar for autonomous vehicles","authors":"H. Ha, Santosh R. Patil, S. Shirguppikar, Shrikant Pawar, Tu Ngoc Do, P. Nguyen, Thanh Thi Phuong Le, L. Nguyen, Tam Chi Nguyen","doi":"10.21303/2461-4262.2023.002766","DOIUrl":"https://doi.org/10.21303/2461-4262.2023.002766","url":null,"abstract":"Modern automobile technology is pushing towards maximizing road safety, connected vehicles, autonomous vehicles, etc. Automotive RADAR is core sensor technology used for ADAS (Advanced Driver Assistance Technology), ACC (Adaptive Cruise Control), AEB (Automatic Emergency Braking System), traffic assistance, parking aid, and obstacle/pedestrian detection. Despite being inexpensive, RADAR technology provides robust results in harsh conditions such as harsh weather, extreme temperature, darkness, etc. However, the performance of these systems depends on the position of the RADAR and its characteristics like frequency, beamwidth, and bandwidths. Moreover, the characterization of varied materials like layers of paint, polish, primer, or layer of rainwater needs to be analyzed. This performance can be predicted through real-time simulation using advanced FEM software like Altair FEKO&WinProp. These simulations can provide valuable insight into the performance of the system, allowing engineers to optimize the system for specific use cases. For example, simulation can be used to determine the optimal parameters of the RADAR system for a given application. This information can then be used to design and build a physical model or prototype that is optimized for the desired performance. These simulations play a prominent role in determining appropriate data collection and sensor fusion, which reduces the cost and time required for the development of a physical model or prototype. The continued growth and demand for advanced safety features in vehicles further highlight the importance of RADAR technology in modern automobile technology. By accurately characterizing the environment and simulating the system's behavior in real time, engineers can optimize RADAR systems for specific use cases, contributing to safer and more efficient driving experiences","PeriodicalId":11804,"journal":{"name":"EUREKA: Physics and Engineering","volume":"7 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82355226","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":"Improving the maneuverability of vehicles by using front swivel axles with separate electric wheels","authors":"M. Podrigalo, N. Artiomov, V. Garmash, S. Horielyshev, I. Boikov, D. Baulin, A. Nakonechnyi, S. Sukonko, Natalia Gleizer, Nataliia Yurieva","doi":"10.21303/2461-4262.2023.002838","DOIUrl":"https://doi.org/10.21303/2461-4262.2023.002838","url":null,"abstract":"There is a need for vehicles to maneuver when there are traffic jams, to overcome narrow streets and various obstacles. This leads to increased requirements for dynamism and maneuverability of vehicles. \u0000The authors present the results of the development and research of the steering control of the vehicle, which provides increased maneuverability. Such circumstances significantly affect the increase in maneuverability of wheeled vehicles, including tractors, for which the use of front suspension axles is possible in terms of layout. The use of a front swing axle with electric motor-wheels with separate control will increase the maneuverability of a two-axle vehicle and minimize the steering effort when turning. \u0000When solving the task, a mathematical model of the movement of the vehicle on a turn was created. The forces in the contact of the wheels with the road surface were determined, which made it possible to determine the forces and moments of resistance to the rotation of the front axle. Rational laws of control of turning the front axle, providing minimal resistance to the movement of the vehicle, were obtained. \u0000A vehicle turning control option is proposed, in which the wheels of the outer and inner sides are alternately braked when the vehicle enters and exits the turn. In addition, it is possible to alternately create a torque difference on the wheels of the outer and inner sides of the front axle. Using the proposed turn control options, it is possible to create a multi-axle vehicle with a rocking axle. \u0000The materials of the article on the controllability of vehicles depending on the design of the steering and front axle are of interest to researchers, designers of mobile equipment, graduate students and students of engineering specialties","PeriodicalId":11804,"journal":{"name":"EUREKA: Physics and Engineering","volume":"39 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89622433","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":"Optimization of technological parameters in ultrasonic welding of the polypropylene fabric using Taguchi and FCCCD methods","authors":"Thanh Quang Le, Thanh-Hai Nguyen, L. Nguyen","doi":"10.21303/2461-4262.2023.002777","DOIUrl":"https://doi.org/10.21303/2461-4262.2023.002777","url":null,"abstract":"Ultrasonic welding is a welding method that has been applied for welding nonwoven fabrics, with many advantages such as fast speed, high reliability, easy automation and especially less pollution to the environment. This paper studies the optimization of technological parameters in the welding process such as welding time, pressure, and weld shape on the breaking strength of ultrasonic welding of Polypropylene (PP) nonwovens. To evaluate the influence level and find the reasonable technological parameters domain in the paper, the Taguchi method is used in combination with the face-centered central composite design (FCCCD) response surface method. The research results have determined the regression equations used to calculate the breaking strength for each weld shape as well as the optimal domain for the main technological parameters, ensuring the breaking strength of the weld. There are different degrees of influence of technological parameters (shape of the weld zone, welding time and welding pressure) on the breaking strength of ultrasonic welds. Among them, the influence level of welding time t is 45.31 %, the weld shape is Pattern 2 with the rate of 30.03 %, and the welding pressure is 24.66 %. Carrying out a verification test with the welding parameters: t=1.6 s, p=3.1 kgf/cm2, two patterns ( Pattern 2 and Pattern 3), the result of breaking strength for patterns was achieved. Pattern 2 has a difference of 1.19 % between the regression equation results and the actual experimental results, while the figure for Pattern 3 is 0.77 %. From these results, it is possible to select the appropriate technological parameters for ultrasonic welding equipment when processing products from nonwoven fabrics to ensure the highest quality and productivity","PeriodicalId":11804,"journal":{"name":"EUREKA: Physics and Engineering","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88149556","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":"Development of mechanical property prediction model and optimization for dissimilar aluminum alloy joints with the friction stir welding (FSW) process","authors":"Y. Pookamnerd, Panuwat Thosa, Sittichai Charonerat, Suriya Prasomthong","doi":"10.21303/2461-4262.2023.002776","DOIUrl":"https://doi.org/10.21303/2461-4262.2023.002776","url":null,"abstract":"Friction stir welding (FSW) is a solid-state joining process used to weld dissimilar aluminum alloys with varying material properties and compositions. Unlike traditional welding methods, FSW does not involve melting the materials being welded but instead uses a rotating tool to heat and stir the materials until they are in a plastic state. The process results in a welded joint with high strength, excellent ductility, and minimal distortion, making it a popular choice in various industries, including aerospace, automotive, and marine. AA6061-T6 (Mg-Si) and AA7075 (Al-Zn-Mg-Cu) aluminum alloys are one of the most popular grades of aluminum alloys used in current manufacturing industries, such as aerospace and automotive, joined by the Friction Stir Welding Process (FSW) technique. Taguchi orthogonal array (L9) experimental design was applied to reduce the number of insignificant factors in the process. First, the study determines three welding factors: rotation speed, travel speed, and pin eccentricity. Investigations found that travel speeds significantly on tensile strength (Ts) and elongation ( %El), but the rotational speed and tool eccentricity did not affect Ts and %El. Furthermore, considering the fabricated parameters on the hardness (HV) of the joint, it was found that all factors unaffected the HV of the joint zone at a 95 % confidence level. Next, examine the microstructure; Mg2Al3 and Al2O3 intermetallic compounds were found in the weld. Therefore, investigating the crystallite size found that welding significantly affects the crystallite size. Finally, consider the fracture surface, experimental condition A2B1C2 (optimal parameter), which is the parameter with the highest tensile strength having dimple fracture characteristics. On the other hand, the welding condition A1B3C3, the parameter with the lowest tensile strength, Small and fine dimple fracture with cleavage fracture. Because the material is highly ductile and can undergo large deformations before it is damaged. On the other hand, materials with low tensile strength exhibiting cleavage fracture indicate that the materials are brittle and can break easily under stress","PeriodicalId":11804,"journal":{"name":"EUREKA: Physics and Engineering","volume":"25 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84850320","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":"The development of cognitive workload management framework based on neuronal dynamics principle to maintain train driver’s health and railway safety","authors":"S. Sugiono, W. Nugroho, Bayu Rahayudi, A. Lintangsari, A. Lustyana","doi":"10.21303/2461-4262.2023.002652","DOIUrl":"https://doi.org/10.21303/2461-4262.2023.002652","url":null,"abstract":"Fatigue increases the tendency of poor train driving strategy decision. Decision making in cognitive overload and cognitive underload situation mostly outputs bad decisions. Accordingly, train driver’s cognitive function is required to be sTable during travel so that they can give correct response at a given situation. This study constructs a conceptual framework for cognitive workload management (CWM) of train driver by taking the energy expenses from cognition into the account. This study combines objective and subjective cognitive workload analysis to evaluate train driver duty readiness. The objective load analysis was performed through energy level approximation based on neuronal dynamics simulation from 76 brain regions. The cognitive energy expenditure (CEE) calculated from neuron action potential (NAP) and the ion-membrane current (IMC) from the simulation results. The cognitive load (CL) approximated by converts the continuous time-based CEE to discrete frequency-based CL using Fourier series. The subjective cognitive workload obtained from train simulation results followed by 27 participants. The participants fill the questionnaire based on their simulated journey experience. The results of the evaluation used to build readiness evaluation classifier based on control chart. The control chart evaluation helps the management to determine weekly rest period and daily short rest period treatment base on each train driver workload. The CWM framework allows different recovery treatment to be applied to each train driver. The impact of the CWM application is the performance of train drivers are kept stable. Thus, the CWM framework based on CEE is useful to prevent physical and mental fatigue","PeriodicalId":11804,"journal":{"name":"EUREKA: Physics and Engineering","volume":"16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90846162","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":"A comparison study of the behaviors of single-phase turbulent flow at low to moderate Reynolds numbers through a vertical pipe: 3D counters analysis","authors":"Amjed Ali, A. Morad, Rafi M. Qasim","doi":"10.21303/2461-4262.2023.002854","DOIUrl":"https://doi.org/10.21303/2461-4262.2023.002854","url":null,"abstract":"The study presented three-dimensional (3D) analysis of water's upward flowing through the vertical pipe under turbulent characteristic considerations. Both numerical constructed and improved the model of 3D for cylindrical coordinates of governing equations for incompressible turbulent flow with the Reynolds Average Navier-Stokes (RANS) model using the improved constants of the (k–ε) type. The present model is then compared with a previous study to give the feasibility of the present single-phase turbulent flow parameters. The pipe length is tested to measure how much it affected the turbulent parameters though one of the expected factors is the turbulent time scale. On the other hand, the model is numerically examined to determine the velocity profile, shear rate, and surface deformation of the water domain. While the pressure distribution, turbulent kinetic energy, and turbulent dissipation rate, these parameters are classified as the mechanic's system factors. The simulation is done with wide software used to simulate industrial is COMSOL 5.4 Multiphysics software. The results obtained increased the velocity of three inlet water velocities used ranging from (0.087, 0.105, and 0.123 m/sec) of upward flow. High fluctuation in the water flow moves along the entire pipe length and it can notice the sensitivity to any change in water properties or mechanical properties. The liquid upward flow in turbulent conditions is suffered from many characteristics such them related to liquid properties and others related to the mechanics of the application through the systems. The interaction between the fluid film (fluid boarded the pipe inner diameter) has been observed by the shear rate and liquid surface deformation","PeriodicalId":11804,"journal":{"name":"EUREKA: Physics and Engineering","volume":"50 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90030297","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":"The design of a fully balanced current–tunable active RC integrator","authors":"Sittisak Roungrid, Chadarat Khwunnak, Samran Lertkonsarn","doi":"10.21303/2461-4262.2023.002765","DOIUrl":"https://doi.org/10.21303/2461-4262.2023.002765","url":null,"abstract":"The design of the active RC integrator presented in this research utilizes a fully balanced technique and current-tunable frequencies to create the active RC integrator and reliable circuit. The circuit is made up of six npn bipolar junction transistors (BJT), six resistors (R), and a capacitor (C), with the fully balanced technique used to make the circuit structure uncomplicated and symmetrical with signal differencing. This approach results in a low number of internal devices in the circuit, making it an attractive option for integrated circuit (IC) development. One of the key features of the fully balanced current-tunable active RC integrator is its ability to be frequency-tunable with bias current (If). This feature enables the circuit to be used in a variety of applications, including filter circuits, communication signal generators, instrumentation signal generators, and various automatic controls. The fully balanced design also ensures that the circuit is stable and robust, even in the presence of device parameter variations. To evaluate the performance of the active RC integrator, simulations were conducted using Pspice. \u0000The results show that a fully current-tunable active RC integrator can be precisely tuned with the active bias to a value consistent with the theoretically calculated value. This demonstrates the efficiency and reliability of the circuit design and simulation method. The Monte Carlo (MC) method was also used to analyze the circuit performance in cases where the resistor (R) and capacitor (C) device had a 10 percent error and the transistor gain (β) was set to an error of 50 percent. The MC analysis showed that the phase shift (degree) and magnitude (dB) of the circuit were stable, and the circuit's performance was not significantly impacted by the device parameter variations. This further demonstrates the robustness and versatility of the fully balanced current-tunable active RC integrator design. Finally, harmonic distortion was evaluated to confirm the performance of the designed and developed fully balanced current-tunable active RC integrator. The results showed low levels of harmonic distortion, which indicates that the circuit is suitable for high-performance applications that require low distortion","PeriodicalId":11804,"journal":{"name":"EUREKA: Physics and Engineering","volume":"466 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83073048","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":"The technical assessment of the level of innovative traction transmission of railway vehicle","authors":"Ayaz Abdullaev, I. Huseynov, Israil Elyazov, Ramin Abdullaev","doi":"10.21303/2461-4262.2023.002823","DOIUrl":"https://doi.org/10.21303/2461-4262.2023.002823","url":null,"abstract":"The article deals with the development of an innovative model of traction transmissions of railway vehicles with a higher technical level, which allows to eliminate the existing shortcomings of the mechanical system, simplify the repair processes and reduce the cost, and evaluate its technical level. By reducing the overall dimensions and weight of the mechanical system, increasing reliability due to equal distribution of the load and shortening the power arm, as well as reducing the number of structural elements, increasing the useful work coefficient due to the reduction of the mass of double sliding pads and rotating parts, saving electricity and thereby improving the technical level of rail transport. Traction transmissions consisting of an innovative reducer are offered that ensure the increase. \u0000The technical level of the proposed dart transmission is determined based on three compatibility parameters with a creative approach. Compatibility parameters are determined according to the minimum value of the geometric dimensions characterizing the mass of the mechanical system, the maximum value of the useful work coefficient characterizing economic efficiency, as well as the maximum values of the degree of reliability characterizing safety. The technical level of the proposed project transmitter is determined and compared with existing buildings, its technical and economic advantages are highlighted. As a result of the application of the proposed innovative reducers in the traction drives of railway vehicles, the basis is created for reducing the cost and maintenance costs of traction vehicles, increasing the level of traffic safety, as well as improving the traction and braking characteristics","PeriodicalId":11804,"journal":{"name":"EUREKA: Physics and Engineering","volume":"7 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80904132","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":"Investigation on high-strength low alloy 0.35Cr-1.9Ni-0.55Mo steel deposited on 20Cr substrate by wire and arc-based directed energy deposition","authors":"D. Vu, V. Le","doi":"10.21303/2461-4262.2023.002837","DOIUrl":"https://doi.org/10.21303/2461-4262.2023.002837","url":null,"abstract":"This article aims to observe the microstructure, mechanical properties, and interface bonding of a 0.35Cr-1.9Ni-0.55Mo alloy deposited on 20Cr steel by wire and arc-based directed energy deposition (WA-DED). For this purpose, different characterization techniques such as optical microscope, scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), and high-resolution X-ray diffractometer were used to analyze microstructure, chemical composition, and phases of the deposited material. Microhardness and tensile tests were also carried out. The results show that the microstructure of the deposited material is relatively homogeneous with a slight increase in grain size from the bottom to the top of the deposited part, thus resulting in a gradually decreasing trend in microhardness, from 288±16.78 HV0.1 (in the bottom) to 256±17.04 HV0.1 (in the top). The heat-affected zone (HAZ) is the hardest (301±2.70 HV0.1), while the substrate has the lowest microhardness (203±17.64 HV0.1). The tensile strengths of deposited materials are relatively isotropic in both the horizontal direction (HD) and vertical (VD) direction: UTSVD = 1013±9.29 MPa, USTHD = 985±24.58 MPa, YS(0.2%)VD = 570±4.51 MPa, and YS(0.2%)HD = 614±19.66 MPa. The tensile strengths of interface specimens are also comparable to those of the substrate materials (e.g., 951 vs. 972 MPa in UTS), indicating an excellent metallurgical bonding between the deposited and substrate materials. The results of this work confirm the efficiency of WA-DED technique to produce high-quality components in industry","PeriodicalId":11804,"journal":{"name":"EUREKA: Physics and Engineering","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89230568","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":"The development of the solution search method based on the improved bee colony algorithm","authors":"A. Shyshatskyi, A. Ishchenko, Serhii Salnyk, Oleksandr Trotsko, L. Shabanova-Kushnarenko, V. Velychko, Ruslan Kornienko","doi":"10.21303/2461-4262.2023.002891","DOIUrl":"https://doi.org/10.21303/2461-4262.2023.002891","url":null,"abstract":"Active digitization of people's daily life leads to the use of the decision-making support systems (DMSS). DMSS is actively used in data processing, forecasting the course of various processes, providing informational support for the decision-making process by decision makers. However, a number of problems arise while evaluating monitoring objects, namely: a large number of destabilizing factors affecting the efficiency of the processes of information collection, processing and transmission; high dynamism of changes in the state and composition of heterogeneous monitoring objects during the conduct of hostilities (operations); high dynamism of conducting hostilities (operations); the uncertainty of the initial situation and the noise of the initial data. In this article, a method of finding solutions based on an improved bee colony algorithm was developed. \u0000The efficiency of information processing is achieved by learning the architecture of artificial neural networks; taking into account the type of uncertainty of the information to be evaluated; the use of an improved algorithm of the bee colony, the use of an unordered linguistic scale of measurements with adjustment coefficients for the degree of awareness and the degree of noise of the initial data. An approbation of the use of the proposed method was carried out on the example of assessing the state of the operational grouping of troops (forces). The method is proposed to be used in the development of software for automated systems of control of troops and weapons, namely, in the modernization of existing and development of new automated systems of control of troops and weapons. The evaluation of the effectiveness of the proposed method showed an increase in the efficiency of the evaluation at the level of 21–28 % in terms of the efficiency of information processing","PeriodicalId":11804,"journal":{"name":"EUREKA: Physics and Engineering","volume":"111 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85806774","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}