Stochastic dynamic simulation of railway vehicles collision using data-driven modelling approach

Using stochastic dynamic simulation for railway vehicle collision still faces many challenges,such as high modelling complexity and time-consuming.To address the challenges,we introduce a novel data-driven stochastic process modelling(DSPM)approach into dynamic simulation of the railway vehicle collision.This DSPM approach consists of two steps:(i)process description,four kinds of kernels are used to describe the uncertainty inherent in collision processes;(ii)solving,stochastic variational inferences and mini-batch algorithms can then be used to accelerate computations of stochastic processes.By applying DSPM,Gaussian process regression(GPR)and finite element(FE)methods to two collision scenarios(i.e.lead car colliding with a rigid wall,and the lead car colliding with another lead car),we are able to achieve a comprehensive analysis.The comparison between the DSPM approach and the FE method revealed that the DSPM approach is capable of calculating the corresponding confidence interval,simultaneously improving the overall computational efficiency.Comparing the DSPM approach with the GPR method indicates that the DSPM approach has the ability to accurately describe the dynamic response under unknown conditions.Overall,this research demonstrates the feasibility and usability of the proposed DSPM approach for stochastic dynamics simulation of the railway vehicle collision.

Blunt aortic injury-traumatic aortic isthmus pseudoaneurysm with right iliac artery dissection aneurysm:A case report

BACKGROUND Blunt aortic injury is a special type of aortic disease.Due to its low incidence,high prehospital mortality and high probability of leakage diagnosis,the timely identification of patients with blunt aortic injury who survive the initial injury has always been a clinical challenge.CASE SUMMARY We report a case of traumatic aortic pseudoaneurysm with right iliac artery dissection aneurysm that was diagnosed 3 mo after a traffic accident.The patient is a 76-year-old male who was knocked down by a fast-moving four-wheel motor vehicle while crossing the road(the damage mechanism was side impact).He received chest,cranial computed tomography(CT)and whole abdomen enhanced CT in the local hospital.The images suggested subarachnoid hemorrhage,right frontoparietal scalp hematoma,fracture of the right clavicle and second rib,lumpshaped mediastinal shadow outside the anterior descending thoracic aorta(mediastinal hematoma),mesenteric vascular injury with hematoma formation,pelvic fracture,and subluxation of the left sacroiliac joint.After the pelvic fracture was fixed with an external stent,he was sent to our hospital for further treatment.In our hospital,he successfully underwent partial resection of the small intestine and CT-guided screw internal fixation of the left sacroiliac joint and returned to the local hospital for rehabilitation treatment.However,since the accident,the patient has been suffering from mild chest pain,which has not aroused the attention of clinicians.During rehabilitation,his chest pain gradually worsened,and the thoracic aorta computed tomography angiography performed in the local hospital showed a pseudoaneurysm in the initial descending segment of the aortic arch.After transfer to our hospital,a dissecting aneurysm of the right external iliac artery was incidentally found in the preoperative evaluation.Finally,endovascular stent graft repair was performed,and he was discharged on the 10th day after the operation.No obvious endo-leak was found after 4 years of follow-up.CONCLUSION We highlight that emergency trauma centers should consider the possibility of aortic injury in patients with severe motor vehicle crashes and repeat the examination when necessary to avoid missed diagnoses.

Highway Concrete Guardrail Lifting Scheme and Safety Performance Verification

In order to achieve the old fence of reuse, improve the safety performance of guardrail, barrier structure does not meet the requirements, make full use of the old concrete guardrail on the basis of heightening, through computer simulation experiment were analyzed, and optimization design, through the real car collision test, make the concrete guardrail after heightening structure satisfies the requirement of the safety performance of current specification. The results show that the protective performance of the two guardrail schemes meets the requirements of the current guardrail evaluation standards through the computer simulation experiment. Through the optimized design of scheme 1, the actual car crash test proves that the enhanced structure of Minhua TYPE II concrete guardrail can meet the requirements of safety performance evaluation. The research results provide an important basis for the transformation of the guardrail and the revision of the current design of expressway in China.

Spatio-Temporal Patterns of Wildlife Road Mortality in Golestan National Park-North East of Iran

Nowadays, wildlife road mortality is acknowledged as a main source of threatening long-term survival of wildlife. This paper as the first to analysis wild life vehicle collisions in Iran, aims to reconstruct and interpret the spatio-temporal patterns of WVCs on Asiaei highway in Golestan National Park (GNP). With the collaboration of environmental protection department of GNP, we identified about 1900 WVC Records involving 34 different species of mammals, birds, reptiles and amphibians between 2004 and 2013. Mammals were involved in more than 50% of overall WVCs, among which wild boar (Sus scrofa), Golden Jackal (Canis aureus), Red Fox (Vulpes vulpes), hedgehog (Erinaceus concolor), stone marten (Martes foina) and porcupine (Hystrix indica) were involved in more than 90% of mammals’ mortalities;So, we focused on analyzing spatio-temporal pattern of vehicle collisions of these six mammal species. During the study period, these species have undergone 95% increase in road mortalities, averagely. Detailed temporal analyses exhibited an increasing trend of road mortalities from spring to summer and then a reducing one to late winter. It was shown that a large number of collisions occurred in holiday periods when recreational trips considerably increased the traffic volume of Asiaei highway. Preliminary inspection of spatial patterns using Kernel density analysis revealed six collision hotspots, mostly located in the road bends with densely forested land cover on both sides;the promenades along the road seemed to play a significant role too. Scale dependency analyses of collision patterns, demonstrated clustering pattern at micro scales less than 10 km, randomness at meso scales 10 - 20 km and both regularity and clustering at macro scales more than 20 km. This paper suggests that road mortality of common species in GNP is a momentous issue, which needs to be considered by relevant governmental and public organizations. We also emphasize that the analyses of spatial and temporal patterns of WVCs are fundamentals to plan for mitigate wildlife road mortality.

Multi objective optimization method for collision safety of networked vehicles based on improved particle optimization

The crashworthiness and energy absorption optimization of automobile structure is an importantresearch content of the modern automobile industry. Facing the problem that traditionaloptimization methods are difficult to find the optimal solution for multi-objective parametersof vehicle structure crashworthiness problem, a multi-objective optimization method of vehiclecrash safety based on improved particle swarm optimization is proposed. Through the collectionand optimization of vehicle collision safety parameters, the vehicle structure performance isimproved, and the vehicle regression model is constructed. Using this method, the front-endstructure reinforcement of the vehicle is taken as the design variable. In order to realize themulti-objective optimization design method of vehicle collision safety, the multi-objective optimizationparameters of vehicle frontal collision and offset collision are taken as the objectivefunction. Finally, the simulation results show that the multi-objective optimization method basedon an improved particle swarm optimization algorithm has an obvious effect on the optimizationof vehicle structure crash safety.

Collision mitigation and vehicle transportation safety using integrated vehicle dynamics control systems

The aim of this paper is to investigate the effect of vehicle dynamics control systems （VDCS） on both the collision of the vehicle body and the kinematic behaviour of the ve- hicle＇s occupant in case of offset frontal vehicle-to-vehicle collision. A unique 6-degree-of- freedom （6-DOF） vehicle dynamics/crash mathematical model and a simplified lumped mass occupant model are developed. The first model is used to define the vehicle body crash parameters and it integrates a vehicle dynamics model with a vehicle front-end structure model. The second model aims to predict the effect of VDCS on the kinematics of the occupant. It is shown from the numerical simulations that the vehicle dynamics/crash response and occupant behaviour can be captured and analysed quickly and accurately. Yurthermore, it is shown that the VDCS can affect the crash characteristics positively and the occupant behaviour is improved.