Objective evaluation of human perception of automotive sound based on physiological signal of human brain

This paper presents a novel approach to apply the physiological signal of the human brain to the sound quality evaluation of automotive sound. In the previous work, psychoacoustic metrics were applied to the sound quality evaluation of automotive sound. Loudness among psychoacoustic metrics is used for one of major sound metrics for the objective evaluation of the sound quality of the acceleration sound inside a car. Subjective evaluation of the sound quality of the acceleration sound shows different results depending on the two different groups of participants. One group liked powerful sound when a car is accelerated: the other group liked the refine sound. Loudness of the acceleration sound is not correlated with the subjective rating of the former group whilst it is correlated with that of the latter group. This evaluation suggests that for the people who like the powerful acceleration sound, it needs to find the sound metric for the objective evaluation of the sound quality of the acceleration sound. In this paper, a driver’s brain signal is measured using electroencephalography (EEG) when a driver hears the acceleration sound of passenger cars. The signal is analyzed to obtain the relationship between brain signals and human perception. According to these results, the alpha wave correlates to the human perception of powerful sound quality of passenger cars. This interesting relationship can be used for objective evaluation of passenger car sounds.     

Examination of nanoparticles from gasoline direct-injection (GDI) engines using transmission electron microscopy (TEM)

Gasoline direct-injection (GDI) engines have been reported to produce significantly more particulate matter (PM) mass and particulate number (PN) emissions than do port-fuel-injection (PFI) spark ignition engines. Because smallsized particles are of great concern in terms of their regulation, transmission electron microscopy (TEM) was used to evaluate the sizes of primary and aggregate particles that were thermophoretically collected from three different GDI engines under various engine operating conditions. A low load and retarded fuel injection generally reduced the particle size. Consequently, when the fuel injection timing was delayed at low loads, primary and aggregate particles became extremely small. In particular, a number of nanoparticles were sub-23-nm particles. Careful high-resolution TEM (HRTEM) analyses provided the first evidence that these nanoparticles are solid carbon particles with clear fringe patterns and young soot (and/or highly condensed semi-volatiles) with amorphous carbon patterns. Therefore, this result suggests that the current cut-off size at 23 nm for PN regulation in Euro 6 must be further reduced to include sub-23-nm carbon nanoparticles.     

Warning standards study of real-time monitoring for anti-collapse in large cross-sefction tunnel of soft and weak surrounding rockEI北大核心

Research purposes: The statistics for tunnel disasters showed that the quantities and casualties of tunnel collapse are much higher than other tunnel disasters. Achieved warning before collapse in tunnel construction, can greatly reduce the tunnel collapse hazards. The key to achieve anti-collapse warning in soft and weak surrounding rock tunnel is to obtain anti-collapse warning standards. Therefore, it is necessary to study tunnel anti-collapse warning standards to guide safe tunnel construction. Research conclusions: (1) Deformation of the tunnel is relevant to hydrogeological conditions, construction method, construction progress and other factors. Currently, the standard values in criterion were not suitable for tunnel collapse warning. (2) It is practicable to achieve anti-collapse monitoring by relative deformation, because anti-collapse real-time monitoring focused on dome relative deformation differently from routine monitoring in soft and weak surrounding rock tunnel. (3) The reference value of tunnel anti-collapse real-time monitoring is determined by displacement limit value in criterion, the maximum value of the measured displacement in similar project and the measured data in tunnel project. (4) The field experiment indicated that the reference value could meet tunnel anti-collapse warning. Therefore, the research results can be applied to large cross-section tunnel of soft and weak surrounding rock.     

Research on the thrust output of a long primary double-sided linear induction motorEI北大核心

Research purposes: Based on Maxwell equations and T-type equivalent circuit of linear induction motor, we analyze the electromagnetic thrust output of a double-sided linear induction motor in the case of edge effect, and use the finite element method and simulation to test the effectiveness of the theoretical calculation. We further derivate the mathematical expressions of a double-sided linear induction motor, build the simulation model by parameter design, and experimentally analyze the slip frequency control thrust output in conditions of different operating. Through analysis of the output characteristics of the electromagnetic force, optimal control of constant current slip frequency is achieved. Research conclusions: (1) We calculate various mechanical properties of a bilateral linear induction motor through its mathematical model and equivalent circuit, and derive the corrected coefficients of the horizontal and vertical edge effect. When the motor runs at a high speed, the edge effect has little influence on the output of the electromagnetic force. (2) We use the finite element computer software to establish the simulation model of a bilateral linear induction motor, and compare the theoretical calculation and simulation data: the simulation results are consistent with theoretical calculation, thus ensuring the validity of the mathematical model. (3) We simulate and analyze the influence of slip frequency, speed, suspension air gap, and length of the mover on electromagnetic force. At different speeds, properly adjusting the slip frequency can increase the output of electromagnetic force. For low speed, the optimal slip frequency is near 2 Hz; for high speed, the optimal slip frequency is between 4.0 Hz and 6.0 Hz. When satisfying the motor's rated condition, the optimal control of electromagnetic force is achieved. (4) The research result of double-sided linear induction motor can provide important implications for the electromagnetic launch system of an aircraft carrier.     

CFD validation studies for a high-speed foil-assisted semi-planing catamaran

This paper details the CFD validation studies carried out as a prerequisite for multi-fidelity CFD-based design optimization of high-speed passenger-only ferries aimed at reducing far-field wake energy that causes beach erosion. A potential flow program (WARP) and a URANS program (CFDSHIP) were validated using full-scale measurements of resistance, sinkage, trim, and far-field wake train obtained over a wide range of speeds for two high-speed semi-planing foil-assisted catamarans: Spirit (LOA-22 m) and 1060 (LOA-17 m). This study posed a unique combination of challenges for CFD modeling: the foil appended geometry required complicated surface overset grids, the effect of the waterjet and wind resistance had to be modeled, and a method had to be devised to extrapolate the calculated near-field elevation to get the far-field wake train using Havelock sources. A more concentrated effort was applied to the URANS verification and validation which forms the focus of this paper. The results show that URANS is able to accurately predict the resistance and motions for both vessels when coupled with models that account for the propulsors and air resistance. The overall accuracy of URANS for the performance analysis of the foil-assisted, semi-planing catamarans was adequate to warrant its use as a tool for subsequent design and optimization of a new vessel with significantly reduced wakes.     

A proposal of reliability-based design formats for ultimate hull girder strength checks for bulk carriers under combined global and local loadings

The purpose of this paper is to provide a basis for the development of reliability-based design formats for ultimate hull girder strength checks for bulk carriers in hogging conditions under combined global and local loading and to estimate implied safety levels in current rule practices for hull girders. The effect of alternative definitions of characteristic still-water loads on the safety format and, hence, the safety factors is assessed. The effect of systematic (bias) model uncertainties associated with loads and strength on the reliability measures is investigated.     

Modelling commuting mode choice with explicit consideration of carpool in the choice set formation

This article investigates the carpool mode choice option in the context of overall commuting mode choice preferences. The article uses a hybrid discrete choice modelling technique to jointly model the consideration of carpooling in the choice set formation as well as commuting mode choice together with the response bias corrections through the accommodation of measurement equations. A cross-nested error structure for the econometric formulation is used to capture correlations among various commuting modes and carpool consideration in the choice set. Empirical models are estimated using a data set collected through a week-long commuter survey in Edmonton, Alberta. The empirical model reveals many behavioural details of commuting mode choice and carpooling. Interestingly, it reveals that interactions between various Travel Demand Management (TDM) tools with the carpooling option can be different at different level of decision making (choice set formation level and final choice making level).     

Behavioural responses to vehicle emissions charging

Road pricing as an economic construct is not a new phenomenon in transportation research. Whilst fuel taxation and tolling of roads are common ways of raising revenue in many countries, these initiatives are primarily aimed at road infrastructure financing. Worldwide there has been growing interest in pricing structures designed to also manage the growing levels of traffic congestion and, in recent times, an increasing focus on generating reductions in carbon emissions from vehicle ownership and use. This paper presents a stated choice experiment undertaken in response to the increasing interest in the environmental externalities of travel behaviour. The aim of this choice experiment is to identify the potential to switch to more fuel efficient cars that emit lower emissions, under differing pricing and technology scenarios. Results indicate that annual and variable emissions surcharges targeted very specifically to vehicle emission rates have a noticeable role in modifying vehicle purchasing decisions.     

Large-scale road network vulnerability analysis: a sensitivity analysis based approach

Traditionally, an assessment of transport network vulnerability is a computationally intensive operation. This article proposes a sensitivity analysis-based approach to improve computational efficiency and allow for large-scale applications of road network vulnerability analysis. Various vulnerability measures can be used with the proposed method. For illustrative purposes, this article adopts the relative accessibility index (AI), which follows the Hansen integral index, as the network vulnerability measure for evaluating the socio-economic effects of link (or road segment) capacity degradation or closure. Critical links are ranked according to the differences in the AIs between normal and degraded networks. The proposed method only requires a single computation of the network equilibrium problem. The proposed technique significantly reduces computational burden and memory storage requirements compared with the traditional approach. The road networks of the Sioux Falls city and the Bangkok metropolitan area are used to demonstrate the applicability and efficiency of the proposed method. Network manager(s) or transport planner(s) can use this approach as a decision support tool for identifying critical links in road networks. By improving these critical links or constructing new bypass roads (or parallel paths) to increase capacity redundancy, the overall vulnerability of the networks can be reduced.