Characterizing Driver Stress Using Physiological and Operational Data from Real-World Electric Vehicle Driving Experiment

Electric Vehicle (EV) is becoming a viable and popular option, but the acceptance of the technology can be challenging and lead to an elevated driving stress. The existing studies on stress of vehicle driving has been mainly limited to the non-EVs or survey analysis. In this research, EV driving data of 40 subjects is analyzed, where each subject was asked to drive an EV over a 53 km course in a suburban city of South Korea. Physiological data including electroencephalogram (EEG) and eye-gazing were obtained along with vehicle operational data such as state of charge, altitude, and speed. The dataset was rich in information, but individual difference and nonlinear patterns made it extremely difficult to draw meaningful insights. As a solution, an information-theoretic framework is proposed to evaluate mutual information between physiological and operational data as well as the entropy of physiological data itself. The result shows two groups of subjects, one not showing much evidence of stress and the other exhibiting sufficient stress. Among the subjects who showed sufficient driving stress, 9 out of the top 10 high EEG-entropy drivers were female, one driver showed a strong pattern of range anxiety, and several showed patterns of uphill climbing anxiety.     

Hydraulic control system design for a PHEV considering motor thermal management

In this paper, a design method for a PHEV hydraulic control system was proposed considering motor thermal management. Dynamic models of the target PHEV were developed including the hydraulic system, which consists of one mechanical and one electric oil pump. The required motor cooling flow was designed based on the motor temperature, which was obtained from a one-dimensional thermal equivalent circuit model including the heat source and oil spray cooling. Combining the PHEV powertrain model, hydraulic control system model, and the motor thermal model including the cooling system, an integrated simulator was developed for the target PHEV. Using the integrated simulator, the temperatures of MG1 and MG2 were investigated for various motor cooling flow rates when the PHEV underwent a highway driving cycle. The energy consumption of the hydraulic control system was also evaluated. It was found from the simulation results that a hydraulic control system of the target PHEV could be designed that satisfied the required flow for the motor cooling, lubrication and brake control using the design procedure proposed in this study.     

Thermo-oxidative degradation of a carbon black compounded EPDM rubber hose

A method to measure the crosslink density of carbon black was used to analyze the aging behavior of a radiator hose made of carbon black filled EPDM (ethylene-propylene diene monomer) rubber under thermo-oxidative stresses. The crosslink density and the strength of the skin of the rubber specimens initially decreased slightly but then increased over time. The elongation at the break considerably reduced and did not show any similarity to the behaviors of the crosslink density. A possible cause of this reaction might be from the formation of rigid sulphoxide crosslinks and the crosslinks produced by the reaction of unvalcunized sulfurs. Aging the rubber specimens at 180°C caused a slight increase in the crosslink density and a large decrease in tensile strength and elongation. The aging experiment also caused a rapid increase of microhardness in the surface skin region. The formation of carbonyl groups in EPDM molecule chains and the formation of rigid sulphoxide crosslink, rather than the crosslink density variation, may have had a large influence. The changing behaviours of the mechanical properties, molecule chains and crosslinks showed significantly different characteristics in the skin and the interior with aging temperature and time.     

Development of early warning index in Korean shipping industry by using signal approach

ABSTRACT

The study aims to investigate and prevent shipping companies’ insolvency that can be derived from depressed market sentiment in the shipping industry. For this purpose, the paper focuses on developing an early warning index. The main factors that contribute to the change in the shipping industry are derived. Sixty independent variables were accounted in the development of early warning index, some of which are shipping, shipbuilding, and finance. Suggestions drew from the result of early warning index are described as below. Firstly, the results of a signal approach towards independent variables showed lowest the signal error value in newbuilding price of containership, bunker price, Commodity Research Bureau (CRB) commodity index, and order book of bulkship. These indicators have proven to be a high level of variation factor during shipping markets’ crisis. Secondly, the early warning index confirmed that it preceded by 6 months compared to probability of default. Thirdly, in order to validate the accuracy of the early warning index, the adequacy of the model was tested using a mean square error and time lag correlations. As a result of the verification, value proved to be at a high level of compliance at 0.097.     

Reduction of emissions with propane addition to a diesel engine

Recent studies on dual-fuel combustion in compression-ignition (CI) engines, also known as diesel engines, fall into two categories. In the first category are studies focused on the addition of small amounts of gaseous fuel to CI engines. In these studies, gaseous fuel is regarded as a secondary fuel and diesel fuel is regarded as the main fuel for combustion. The objectives of these studies typically involve reducing particulate matter (PM) emissions by using gaseous fuel as a partial substitution for diesel fuel. However, the addition of gaseous fuel raises the combustion temperature, which increases emissions of nitrogen oxides (NO_x). In the second category are studies focused on reactivity-controlled compression-ignition (RCCI) combustion. RCCI combustion can be implemented by early diesel injection with a large amount of low-reactivity fuel such as gasoline or gaseous fuel. Although RCCI combustion promises lower NO_x and PM emissions and higher thermal efficiency than conventional diesel combustion, it requires a higher intake pressure (usually more than 1.7 bars) to maintain a lean fuel mixture. Therefore, in this study, practical applications of dual-fuel combustion with a low air-fuel ratio (AFR), which implies a low intake pressure, were systemically evaluated using propane in a diesel engine. The characteristics of dualfuel combustion for high and low AFRs were first evaluated. The proportion of propane used for four different operating conditions was then increased to decrease emissions and to identify the optimal condition for dual-fuel combustion. Although the four operating conditions differ, the AFR was maintained at 20 (? approximately equal to 0.72) and the 50% mass fraction burned (MFB 50) was also fixed. The results show that dual-fuel combustion can reduce NO_x and PM emissions in comparison to conventional diesel combustion.     

Optimal fuel-cut driving method for better fuel economy

Eco-drive methods are being applied in modern passenger cars in the form of LCD displays showing real-time fuel consumption rates. The eco-drive is one of the most promising methods to enhance the fuel economy of vehicles. The ecodrive method can be made more effective by using the fuel-cut function. The fuel is not injected when the driver does not depress the gas pedal of a vehicle with engine speeds higher than approximately 1,500 rpm above the mid-vehicle speed range. This function is known as the fuel-cut function, and almost every modern vehicle is equipped with this function. The fuel-cut is most frequently activated on downhill sections of highway. Therefore, the CO₂ exhausted from the vehicle can be zero in this downhill section. In this study, the fuel-cut function is simulated with CRUISE of AVL to find the most effective driving pattern in downhill sections. Simulations with the CRUISE software showed that the lower limit of the vehicle speed for fuelcut should be raised to improve fuel economy on steeper downhill sections. The fuel economy can be optimized when the fuelcut coasting and reacceleration is completed in the downhill part of the road. The simulation result was also compared to previous test results. Fuel consumption was reduced by approximately 4% in both the experimental and simulated results for the West Coast Highway in South Korea.     

Comparison of driving characteristics between drivers in Korea and in the united states of America based on driver-vehicle interaction field database

Research and development involving intelligent vehicles of today is geared to safe, driver-friendly and sensitive vehicles that provide a driver with a pleasant and convenient driving environment while preventing him or her from possible risks of accident. In developing convenient and safe vehicles, research on drivers’ driving patterns, reactions and state characteristics depending on road conditions in actual field is essential in order to devise more driver-friendly intelligent vehicles. This paper describes how a driver-vehicle interaction (DVI) field database is built in order to obtain a driver’s input in normal road driving condition on highways, country roads, and city roads, and his or her state information, as well as data on the vehicle and traffic conditions. And the newly built database is compared with the RDCW FOT database established by UMTRI of the US for analysis to suggest that the driving tendencies of drivers in Korea and the road driving conditions are not the same as those in the US, reconfirming the need to establish a DVI field database, which will be used for the development of intelligent vehicles suitable for the Korean environment. The DVI data collected from actual driving in field are anticipated to be widely utilized as basic data for research on various intelligent driving safety systems, advanced driver assistance systems (ADAS) and human-vehicle interface (HVI) that are suitable for the driving environment in Korea.     

Review on characterization of nano-particle emissions and PM morphology from internal combustion engines: Part 2

This paper presents a review of the characterization of physical properties, morphology, and nanostructure of particulate emissions from internal combustion engines. Because of their convenience and readiness of measurement, various on-line commercial instruments have been used to measure the mass, number, and size distribution of nano-particles from different engines. However, these on-line commercial instruments have inherent limitations in detailed analysis of chemical and physical properties, morphology, and nanostructure of engine soot agglomerates, information that is necessary to understand the soot formation process in engine combustion, soot particle behavior in after-treatment systems, and health impacts of the nano-particles. For these reasons, several measurement techniques used in the carbon research field, i.e., highresolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and Raman spectroscopy, were used for analysis of engine particulate matter (PM). This review covers a brief introduction of several measurement techniques and previous results from engine nano-particle characterization studies using those techniques.     

Development of the performance simulator for electric scooters with an in-wheel motor

Due to the increasing use of fossil fuel, carbon dioxide emission also increased and environmental problems have emerged as social issues. Accordingly, the research about electric vehicles as personal transportation has been actively performed. An electric scooter is not as complex as an automobile, but it takes a lot of time and costs to design and develop a new vehicle due to trial and error in selecting the specifications of core components according to consumer’s requirements. In this paper, a performance simulator for an electric scooter with an in-wheel motor at the rear wheel was developed and the simulation results were verified through experiments. For a longer travelling distance with the same energy source, the regenerative braking algorithm that converts kinetic energy into electric energy during braking was applied. The usefulness of the regenerative braking control algorithm was verified through various simulation results.     

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.