Finite element models of headforms are used in experimental simulations of pedestrian protection. In this study, a quick and accurate method for FE modeling of the headforms was developed. This method entailed the initial definition of the dimensional parameters for the mass, centroid, and inertial moment properties of the headform. The equations governing these properties were constructed using the dimensional parameters as design variables. The dimensional parameters meeting the requirements of the relevant regulations were obtained by solving these three equations. A design optimization model was constructed for the material parameters of the outer part of the headform. In this model, the parameters of the material used in the FE model were considered as design variables; the difference between the peak acceleration in a side-impact simulation test and the average value of the regulated acceleration range was used as the objective function; the first-order natural frequency, which was required to be greater than 5,000 Hz, was defined as one of the constraints; the peak drop acceleration, which was required to be within the regulated range of values, was defined as the second constraint. The material parameters were obtained by solving the optimization model. These material parameters meet the dynamic requirements of the regulations for headforms. Based on these three parameters, an FE model of a headform can be constructed quickly and accurately. 相似文献
The warm shrink fitting process is generally used to assemble automobile transmission parts (shafts/gears). However, this
process causes a deformation in the addendum and dedendum of the gear depending on the fitting interference and gear profile,
and this deformation causes additional noise and vibration between the gears. To address these problems, the warm shrink fitting
process is analyzed by considering the error in the dimensional deformation of the addendum and dedendum found when comparing
the results of a theoretical analysis and finite element analysis (FEA). A correction coefficient that reduces this error
is derived through an analysis of the difference in the cross-sectional area between the shapes used for the theoretical analysis
and that of the actual gear, and a closed-form equation to predict the dimensional deformation of the addendum and dedendum
is proposed. The FEA method is proposed to analyze the thermal-structural-thermal coupled field analysis of the warm shrink
fitting process (heating-fitting-cooling process). To verify the closed-form equation using the correction coefficient, measurements
are made of actual helical gears used in automobile transmissions. The results are in good agreement with those given by the
closed-form equation. 相似文献
Transportation - Ride-hailing (ridesourcing) companies such as Uber, Lyft, and Didi Chuxing have been a disruptive force in the urban mobility landscape around the world during the past decade. In... 相似文献
Freight forecasting models have been significantly improved in recent years, especially in the field of goods vehicle behavior modeling. On the other hand, the improvements to commodity flow modeling, which provide inputs for goods vehicle simulations, were limited. Contributing to this component in urban freight modeling systems, we propose an error component logit mixture model for matching a receiver to a supplier that considers two-layers in supplier selection: distribution channels and specific suppliers. The distribution channel is an important element in freight modeling, as the type of distribution channel is relevant to various aspects of shipments and vehicle trips. The model is estimated using the data from the Tokyo Metropolitan Freight Survey. We demonstrate how typical establishment survey data (i.e. establishment and outbound shipment records) can be used to develop the model. The model captures the correlation structure of potential suppliers defined by business function and provides insights on the differences in the supplier choice by distribution channel. The reproducibility tests confirm the validity of the proposed approach, which is currently integrated into a metropolitan-scale agent-based freight modeling system, for practical use.
Objective To map a mouse deafness gene.identify the underlying mutation and develop a mouse model for human deafncss.Methods Genetic lindage cross and genome scan wer used to map a novel mutation named hypoplasia of the membranous labyrinth (hml),which causes hearing loss in mutant mice.Results ① hml was mapped on mouse Chr 10 (~43 cM from the centromere) suggests that the homologous human gene is on 12q22--q24, which was defined on the basis of known mouse-human homologies (OMIM,2004). ② This study has generated 25 polymorphic microsateUite markers, placed 3 known human genes in the correct order in a high-resolution mouse map and narrowed the hml candidate gene region to a 500 kb area. 相似文献