Train Head Research Articles

Numerical and experimental study on the aerodynamic noise characteristics of 600-km/h high-speed maglev trains

Abstract High-speed maglev trains represent a new mode of transportation; however, their 600-km/h traveling speed causes serious aerodynamic noise problems, with very little research on the aerodynamic noise of such trains. To clarify the aerodynamic noise source and radiation characteristics of high-speed maglev trains, both large eddy simulations and wind tunnel experiments with a 1:8 scale three-train model were conducted to obtain the aerodynamic noise source spectrum and spatial distribution characteristics of the maglev train at different speeds; the contribution of the dipole noise source was also analyzed. The results revealed that the train shape has a significant impact on the frequency distribution of the far-field aerodynamic noise below 1 kHz, with the highest sound power concentrated on the train head, especially in the areas around the track joint and streamlined sections. The surface dipole sound source energy increases linearly with speed and is mainly distributed at the bottom of the train head and tail train body. A short-streamlined train exhibited the highest ratio, especially in the trailing edge area, up to 1.42×1011 dB. The far-field sound pressure level of the short-streamlined maglev train is significantly higher, with a maximum difference of about 10 dB(A). The distribution pattern of far-field sound pressure level is influenced by the train type, reflected in the tail train and wake area. Different frequency intervals have different relationships between the acoustic pressure level and frequency; long-streamlined models may enhance broadband features in the sound field distribution of high-speed maglev trains. These findings could be used to guide the aero-acoustic design of maglev trains with a designed speed of 600 km/h.

PDE parametric modeling with a two-stage MLP for aerodynamic shape optimization of high-speed train heads

PDE parametric modeling with a two-stage MLP for aerodynamic shape optimization of high-speed train heads

Effect of geometry simplification and boundary condition specification on flow field and aerodynamic noise in the train head and bogie region of high-speed trains

Effect of geometry simplification and boundary condition specification on flow field and aerodynamic noise in the train head and bogie region of high-speed trains

Evaluating the Accuracy of ChatGPT in Common Patient Questions Regarding HPV+ Oropharyngeal Carcinoma.

Large language model (LLM)-based chatbots such as ChatGPT have been publicly available and increasingly utilized by the general public since late 2022. This study sought to investigate ChatGPT responses to common patient questions regarding Human Papilloma Virus (HPV) positive oropharyngeal cancer (OPC). This was a prospective, multi-institutional study, with data collected from high volume institutions that perform >50 transoral robotic surgery cases per year. The 100 most recent discussion threads including the term "HPV" on the American Cancer Society's Cancer Survivors Network's Head and Neck Cancer public discussion board were reviewed. The 11 most common questions were serially queried to ChatGPT 3.5; answers were recorded. A survey was distributed to fellowship trained head and neck oncologic surgeons at 3 institutions to evaluate the responses. A total of 8 surgeons participated in the study. For questions regarding HPV contraction and transmission, ChatGPT answers were scored as clinically accurate and aligned with consensus in the head and neck surgical oncology community 84.4% and 90.6% of the time, respectively. For questions involving treatment of HPV+ OPC, ChatGPT was clinically accurate and aligned with consensus 87.5% and 91.7% of the time, respectively. For questions regarding the HPV vaccine, ChatGPT was clinically accurate and aligned with consensus 62.5% and 75% of the time, respectively. When asked about circulating tumor DNA testing, only 12.5% of surgeons thought responses were accurate or consistent with consensus. ChatGPT 3.5 performed poorly with questions involving evolving therapies and diagnostics-thus, caution should be used when using a platform like ChatGPT 3.5 to assess use of advanced technology. Patients should be counseled on the importance of consulting their surgeons to receive accurate and up to date recommendations, and use LLM's to augment their understanding of these important health-related topics.

Slim-YOLOv8: A fast and accurate algorithm for surface defect detection of steel strips

Steel strip is an extremely important industrial material and is widely used in various industrial fields. During the production process, surface defects need to be detected quickly and accurately. This study proposes a model. This study proposes a new slim-YOLOv8 (lightweight YOLOv8) detection model. The model is based on YOLOv8 and adopts a lightweight design paradigm, which reduces the number of parameters of the model and enhances the detection real-time performance. At the same time, an online reparameterization method is introduced to enhance the feature extraction capability of the network without raising the inference cost, and to improve the model's detection accuracy for complex defects. Finally, an auxiliary training head that can provide richer gradient information is added to the model to help train the model while preventing model overfitting. The performance of slim-YOLOv8 in mean average precision and parameters was evaluated on the well-known steel strip surface defect detection dataset NEU-DET, reaching a mAP of 85.8% at IoU 0.50 and 50.3% in the IoU 0.50–0.95 range. This is an improvement of 8.3% and 3%, respectively, compared to the baseline model. Meanwhile, the number of parameters of the model was reduced from 3.0 M to 2.7 M, which is 7% lower than the baseline model. The experimental results show that slim-YOLOv8 uses a smaller number of parameters, but has higher accuracy and is able to detect various defects in the dataset well.

Вопросы организации «умного поезда милосердия»

The article is devoted to the problem of digitalization of sanitary trains, which ensure the stage of medical evacuation of victims in emergency situations. In order to improve the quality of medical and diagnostic measures along the route, and the use of existing digital medical services, it is necessary to create a “smart mercy train” (UPM) equipped with modern information and telecommunications facilities. Relevance: At the stage of the digital transformation of Russian Railways, ensuring the timeliness and efficiency of medical evacuation of victims is possible by creating a “smart mercy train” using existing solutions for objects of an intelligent transport system. The choice of equipment for an intelligent transport system is determined by the volume and type of information of a medical and administrative nature. Objective: To assess the projected information flows and functional needs of a “smart” means of medical evacuation by rail in emergency situations. Methods: Methods of expert survey, system analysis and theory of operations research were used. Results: An analysis of existing solutions for the creation of a “smart” means of medical evacuation by rail is presented. The internal and external information flows received by the head of the mercy train, which need special technical support (means of communication), are ranked. The place of the integrated personal electronic medical record at the stages of medical evacuation within the framework of the Unified Military Medical Information System has been determined. The results of the creation of a digital “smart mercy train” are determined. Practical significance: Taking into account the assessment of projected information flows and functional needs of communication users in the UPM made it possible to determine the required types of communication and the speed of information transfer for the implementation of the functions of communication users, which will further calculate the average subscriber load on the UPM communication network.

A novel vortex control method for improving anti-overturning performance of a high-speed train with leeward airbag structures under crosswinds

The high-speed train's head and cross sections have been designed in an innovative way to meet the requirements of aerodynamic drag reduction and crosswind stability of the train. However, with the continuous increase in the running speed of high-speed trains and the continuous reduction of the total weight of the car body, it is critical to develop new strategies to ensure train safety in crosswind environment. In the current study, a novel vortex control method with airbag structure installation on the leeward side (LWS) of the train was proposed to disturb the leeward large vortices, with expectation to weaken the vortices adjacent the train body and increase the surface pressure on the leeward side. The leeward airbag structures (LASs) contribute to reducing the pressure difference between the windward and leeward sides of the train body. As a result, a reduction of the lateral force and overturning moment coefficients is obtained. An amazing observation is that an extra lift force is achieved by LASs, which leads to an anti-overturning moment, further improving the anti-overturning performance of the high-speed train. Compared with the original model, the LASs can decrease the lateral force coefficients by 7.1%, while the lift coefficient is increased by 12.8%, which together reduces the overturning moment coefficient by 13.1%. It indicates that the main influence factor for crosswind stability of the train tends to be changed after the installation of LASs. The aerodynamic performance of the tail car is more sensitive to the LASs as compared to that of the head and middle cars, i.e., the reduction of the overturning moment coefficient is about 44.6% for the tail car, whereas it is only 7.8% and 12.5% for the head and middle cars, respectively. Thus, the LASs proposed in the current work can significantly improve the anti-overturning performance of high-speed trains, which will provide a novel anti-overturning approach for higher-speed trains.

Comparative study on lateral vibration characteristics of the head and tail cars of high-speed trains under unsteady aerodynamic loadings

With the increasing speed of high-speed trains, abnormal vibrations in the tail car pose a threat to its overall stability and running safety. In this study, the aerodynamic and multibody dynamics models for 3-car and 8-car trains are established. The flow field characteristics and dynamic performance around the head and tail cars under both steady and unsteady aerodynamic loadings at a speed of 400 km/h are compared. The results reveal that the surrounding flow field exhibits highly pronounced unsteady characteristics, directly leading to a significant impact of unsteady aerodynamic loadings on the train's dynamic response. Under unsteady loadings, the lateral stability indexes, displacement, velocity, and acceleration of the tail car are all worser compared to those of the head car. Additionally, the larger oscillation amplitudes and frequencies closer to the suspension modal frequencies under unsteady aerodynamic loadings contribute to more pronounced lateral displacements and accelerations, constituting a crucial factor in the observed ‘tail swing' phenomenon for the high-speed train.

Numerical study of aerodynamics drag and flow characteristics of the high-speed train head design

A native design of the Indonesian high-speed train has been developed as an improvement of the previous medium-speed train model. As the design speed is proposed to be increased from 160 km/h to 250 km/h, the nose shape and nose length of the train head were modified into a sharper and longer nose. In this study, numerical simulation of computational fluid dynamics was used to investigate the aerodynamic phenomena and flow behavior around the modified train head and carbodies. The CFD simulation was used as the verification of the shape design and a tool for rapid design changes and optimization. The model configuration is three cars on a real scale by ignoring other parts like the train window and door, pantograph, and train connecting. A k-ε turbulence model was used in the simulation. From this investigation, it is found that the coefficient of drag on the model is calculated to be 0.34. Meanwhile, an experimental wind tunnel test validates the result with a coefficient drag is 0.38 or 10% divergence from the numerical method.

Surrogate-based aerodynamic shape optimization of high-speed train heads: A review of four key technologies

With the increase in running speed, the aerodynamic characteristics of high-speed trains have a significant impact on running stability, energy consumption and passenger comfort. Since the shape of the high-speed train head can directly influence the surrounding airflow, optimizing the head shape is the primary way to improve the aerodynamic performance of the train. This paper reviews current research studies on the surrogate-based aerodynamic shape optimization of high-speed train heads, aiming to provide a comprehensive reference for designers to enhance design efficiency and optimization performance. The entire optimization process is divided into four essential steps, and the key optimization technologies in each step are discussed, including parametric modeling, computational fluid dynamics (CFD) simulation, surrogate model and optimization algorithm. By introducing the practical applications of these technologies, we summarize their advantages and disadvantages and suggest four potential research directions for the future.

Funded childcare should prioritise quality

Louise Livingston, head of training, Maria Montessori Institute

Six-dimensional force/torque sensor for aerodynamic characteristic study of high-speed train with different wind angles under stationary tornado.

Researchers conducted an investigation by tornado simulator to study the impact of wind angle on the aerodynamic characteristics of a reduced (1:150) high-speed train model using six-dimensional force/torque sensor. The reduced scale model size can match the relative size relationship between high-speed train and tornado vortex core in real condition. Results show that the wind angle affects the mean value and standard deviation of the force and moment coefficient of the high-speed train at the same radial position. The variations of the mean value and standard deviation of the pitching moment coefficient of the high-speed train carriage model at 60°and 90°are different from that at other wind angles. The variations of the mean value of the pitching moment coefficient of the high-speed train head model at 0°, 15°and 30°are different from that at other wind angles. The variations of the standard deviation of the pitching moment coefficient of the high-speed train head model at 60°,75°and 90°are different from that at other wind angles. This research will help the further study of the operation safety of high-speed train in the event of a tornado impacting a high-speed train network.

Investigation of the fire hazard of underground space fire scenarios in urban metro tunnels under natural ventilation: Analysis of the impact of tunnel slope on smoke back-layering length

The smoke back-layering length is a crucial parameter for evacuating people in both road and subway tunnel fires. This study investigates the fire hazard induced by carriage fire in inclined metro tunnels under natural ventilation. The parameter ‘transition slope’ is defined to measure the smoke flow from the carriage head in the upstream direction to the tunnel or not due to the stack effect of the tunnel slope. The aim of this paper is to analyse the effects of changes in cross-section, downstream length, tunnel slope, and carriage side-door coupling on smoke behaviour characteristics by experiment and simulation methods. A piecewise function expression between dimensionless smoke back-layering length, downstream length, and tunnel slope for carriage fires in an inclined tunnel under natural ventilation is proposed by theoretical analysis. At the same time, a 1:15 scale model experiment was conducted to initially analyse the characteristics of smoke movement. Following this, full-scale numerical simulations were employed to complement the model experiment and quantify the principles governing smoke movement. The experimental results show that the tunnel slope has a significant effect on the smoke back-layering length. In contrast, the influence of the heat release rate was found to be relatively minor. In addition, simulation results show that the tunnel slope has no significant effect on the smoke back-layering length when the fire location is approximately 20 m from the train head, and the tunnel slope is in the range of 2.29° ∼ 3.43° (4% ∼ 6%). For small tunnel slopes, smoke spreads in the tunnel, and the smoke back-layering length produced by the virtual fire source shows a different law from the previous study model. Finally, the correlation coefficient of the piecewise function in theoretical analysis is fitted by combining the experimental and numerical simulation results. Practical application This study provides valuable insights into the practical implications of controlling and mitigating the impact of fires in inclined metro tunnels. By understanding the critical role of tunnel slope and providing a quantitative tool for smoke spread law assessment, this study contributes to the enhancement of safety measures and the protection of lives in tunnel environments during fire incidents.

Super Parents: Preliminary Findings of a Group-Based Parenting Intervention

Super Parents is a group-based, Extension-led parenting program developed to enhance the parent-child relationship. Implemented by trained Head Start staff using the train-the-trainer model, this effort is achieved by teaching positive parenting practices, increasing parents’ knowledge of child development, instructing parents in activities and exercises for enhancing their child’s executive function skills, and encouraging the use of mindfulness techniques in parenting. The specific aims of our study were to evaluate the program's effectiveness among parents of young children ages 0 to 5 by examining changes in parenting attitudes, mindfulness, executive function, parenting efficacy, stress, and child behavior. Through the use of pre-program and post-program measures, increases were observed in a number of positive parenting behaviors and child outcomes, along with decreases in multiple negative parenting and child behaviors. Findings from this study can inform implementation decisions of other parenting programs or trainings administered by Extension educators.

Influence of Kenya Education Management Institute Training for Head Teachers on Financial Resource Management in Public Secondary Schools in Kisii South Sub-County, Kenya

Management of resources in secondary schools by principals greatly contributes towards successful institutional programmes and projects in their respective schools. Kenya Education Management Institute (KEMI) has taken an integral role in training head teachers on the management of resources. Despite KEMI training the principals on resources and management, schools remain underdeveloped as head teachers get interdicted due to mismanagement of resources. The study was, therefore, paramount in establishing the influence of KEMI training for principals on the management of resources available in secondary schools. The study adopted mixed methods, and therefore, the researcher applied qualitative and quantitative methods through concurrent triangulation design of both qualitative and quantitative data collections at the same time. The target population comprised 73 head teachers and 73 school management committee chairpersons. Using the Central limit theorem, a sample of 25 head teachers and 25 committee chairpersons was selected. Simple random and purposive sampling was used to select the samples from each category of the population; questionnaires were administered among principals, while interview schedules were conducted among school chairpersons. An observation checklist was also used to collect data from the school vicinity. Data analysis involved qualitative data being analysed in themes, while quantitative data was through descriptive statistics used in Statistical Packages for Social Sciences (SPSS 23) and presented using tables and charts. The study established that KEMI training for principals influenced their management of human resources in schools. Through KEMI training, principals acquired knowledge, skills, and attitudes to handle teachers, support staff, pupils and other persons involved in the running of schools. The study recommends that there is a need for principals to conduct staff appraisals, create a motivating and rewarding environment and establish conflict resolution mechanisms

School Administration Related Factors that Influence Access to and use of ICT in Special Schools of Learners with Visual Impairment

The infusion of Information communication technology into teaching and learning in schools is growing by day. Information Communication Technology is now a reliable source of knowledge for transforming and reforming education. However, the school administrators’ personal beliefs and theoriesabout integration of ICT in teaching and learning are widely considered to play a central role in the implementation of the newtechnologies in schools. Therefore, given the role the head teachersplay, there is need to investigate their influence in the access to anduse of ICT in special schools of learners with visual impairments.The findings are significant for it would help policy makers to understand the role of school administration in the implementation of ICT in special schools with learners with visualimpairments. The objective of the study was to establish school administration factors that influence access to and use of ICT in special schools for leaners with visual impairments in Kenya. The study adopted descriptive survey design. The study targeted sevenpublic special primary schoolsforleaners with visual impairments with a population of 1667, 161 teachers, seven head teachers, sevencomputer teachers and seven ministry of education officers. The study sampled three schools situated in different counties in the country; Kiambu county, Meru county and Mombasa county. Judgmental sampling technique, stratified random sampling and simple random sampling were used to draw the samples. The samples consisted of three primary schools for leaners with visualimpairment, 168 learners, 18 class teachers, 3 computer teachers, three head teachers and three Ministry If Education officials in the counties where the schools are situated. Data collection instruments were questionnaires, interview schedules and observation schedules. Content validity was determined by seeking expert review. The Cronbach Alpha formula was used to compute the reliability of the instruments. A reliability co efficient of 0.72 was used to judge the reliability of the instruments. The data collected was analyzed using descriptive statistics. The study found that head teachers are willing to support the learners with visual impairment to access and use ICT in the schools. However, there are hindering factors such as unstable internet connection, low teachers’ capacity to use ICT, lack of enough time allocated toICT learning, some of the head teachers had little knowledge on how to get adapted ICTs for learners with visual impairment andfinally, there was no mechanism or model for accessibility of the ICT and other assistive resources for learners with visual impairments in the schools. The study recommended that the government through the ministry of education to train head teachers and teachers on the use of ICT suitable for learners withvisual impairments in schools and ensure their functionality and availability. There is also need for a model for access of ICT and provision of the learning support for the learners with visual impairments in the special primary schools in Kenya.

Aerodynamic behavior of flaky spalled blocks in high-speed rail tunnel lining under slipstream

As high-speed railway tunnels continue to serve for long periods of time, the tunnel lining is subjected to long-term cyclic tension and compression from train aerodynamic loads, thereby causing cracks to propagate and spalled blocks to fall off, which severely impact the safety of train operation. This paper is based on the improved delayed detached eddy simulation (IDDES) method and establishes a 3D fluid–solid coupling calculation model of spalled block-high-speed train-tunnel-air. Explores the differences in the motion trajectory and force of spalled blocks falling off at different peeling times under the impact of a high-speed train traveling at 300 km/h, and investigates the relationship between the spalled blocks and the changes in train aerodynamic flow field structure and aerodynamic pressure during the motion process in order to understand the aerodynamic behavior and flow field structure mechanism of spalled blocks. Under the action of slipstream, the spalled blocks exhibit a combined form of translation and rotation while falling, with the translation mainly occurring in the longitudinal (X-axis) direction and the rotation being most obvious around the Z-axis. Some significant differences are observed in the translational trajectory and rotational angle of the spalled blocks in the vertical and horizontal directions at different peeling times, and the longitudinal displacement distance is 3 to 38 times the horizontal displacement distance. The maximum rotational angle of the spalled block that peels off when the train head arrives is along the Z-axis.

Current situation in radiation oncology residency—Results of a national survey performed by the working group Young DEGRO of the German Society of Radiation Oncology

BackgroundThe aim of this study was to assess the current status of the radiation oncology (RO) residency programs in Germany. For this, RO residents and RO specialists were surveyed regarding the current situation of the RO residency training and the working conditions in Germany.MethodsThe Continuing Education Section of the Young DEGRO (yDEGRO) Working Group of the German Society of Radiation Oncology (DEGRO) developed a survey to assess (1) the overall satisfaction, learning objectives, and teaching methods used during training; and (2) the perception of the importance of specific disease patterns in RO training. Open-ended questions were also asked to elicit opinions on areas for improvement. From 21 November to 27 December 2022, RO residents registered with DEGRO and/or in the working group yDEGRO were invited to participate anonymously in an online questionnaire.ResultsOverall, 97 participants completed the survey, including 65 RO residents (67%) and 32 RO specialists (33%); 66 (68%) of the respondents reported being employed in the university setting, 23 (23.7%) in the non-university setting, and 8 (8.3%) in private practice. Within the training, heterogeneity was found in the teaching methods used. In terms of knowledge transfer, the greatest importance was accorded to annual continuing education discussions with the head of the residency training (92.8%), participation in tumor boards (85.6%), written training concepts (81.4%), and evaluations at the beginning (76.3%) and end of a rotation (80.4%). The arithmetic mean of satisfaction with specialist training was 6/10 points (SD: 1.99); 88.7% of respondents would like to see a nationally uniform and mandatory curriculum in RO residency training.ConclusionThe study provides suggestions for improving RO medical training in Germany: further development of accompanying education and training programs in cooperation with professional associations, e.g., the DEGRO, structured feedback, and supervision.

A study on aerodynamic noise characteristics of a high-speed maglev train with a speed of 600 km/h

Purpose This study aims to explore the formation mechanism of aerodynamic noise of a high-speed maglev train and understand the characteristics of dipole and quadrupole sound sources of the maglev train at different speed levels.Design/methodology/approach Based on large eddy simulation (LES) method and Kirchhoff–Ffowcs Williams and Hawkings (K-FWH) equations, the characteristics of dipole and quadrupole sound sources of maglev trains at different speed levels were simulated and analyzed by constructing reasonable penetrable integral surface.Findings The spatial disturbance resulting from the separation of the boundary layer in the streamlined area of the tail car is the source of aerodynamic sound of the maglev train. The dipole sources of the train are mainly distributed around the radio terminals of the head and tail cars of the maglev train, the bottom of the arms of the streamlined parts of the head and tail cars and the nose tip area of the streamlined part of the tail car, and the quadrupole sources are mainly distributed in the wake area. When the train runs at three speed levels of 400, 500 and 600 km·h−1, respectively, the radiated energy of quadrupole source is 62.4%, 63.3% and 71.7%, respectively, which exceeds that of dipole sources.Originality/value This study can help understand the aerodynamic noise characteristics generated by the high-speed maglev train and provide a reference for the optimization design of its aerodynamic shape.

Study on dynamic response of high speed train window glass under tunnel aerodynamic effects

PurposeThis paper aims to analyze the bearing characteristics of the high speed train window glass under aerodynamic load effects.Design/methodology/approachIn order to obtain the dynamic strain response of passenger compartment window glass during high-speed train crossing the tunnel, taking the passenger compartment window glass of the CRH3 high speed train on Wuhan–Guangzhou High Speed Railway as the research object, this study tests the strain dynamic response and maximum principal stress of the high speed train passing through the tunnel entrance and exit, the tunnel and tunnel groups as well as trains meeting in the tunnel at an average speed of 300 km·h-1.FindingsThe results show that while crossing the tunnel, the passenger compartment window glass of high speed train is subjected to the alternating action of positive and negative air pressures, which shows the typical mechanic characteristics of the alternating fatigue stress of positive-negative transient strain. The maximum principal stress of passenger compartment window glass for high speed train caused by tunnel aerodynamic effects does not exceed 5 MPa, and the maximum value occurs at the corresponding time of crossing the tunnel groups. The high speed train window glass bears medium and low strain rates under the action of tunnel aerodynamic effects, while the maximum strain rate occurs at the meeting moment when the window glass meets the train head approaching from the opposite side in the tunnel. The shear modulus of laminated glass PVB film that makes up high speed train window glass is sensitive to the temperature and action time. The dynamically equivalent thickness and stiffness of the laminated glass and the dynamic bearing capacity of the window glass decrease with the increase of the action time under tunnel aerodynamic pressure. Thus, the influence of the loading action time and fatigue under tunnel aerodynamic effects on the glass strength should be considered in the design for the bearing performance of high speed train window glass.Originality/valueThe research results provide data support for the analysis of mechanical characteristics, damage mechanism, strength design and structural optimization of high speed train glass.