Review on characterization of nano-particle emissions and PM morphology from internal combustion engines: Part 1

This paper is review of the characterization of exhaust particles from state-of-the-art internal combustion engines. We primarily focus on identifying the physical and chemical properties of nano-particles, i.e., the concentration, size distribution, and particulate matter (PM) morphology. Stringent emissions regulations of the Euro 6 and the LEV III require a substantial reduction in the PM emissions from vehicles, and improvements in human health effects. Advances in powertrains with sophisticated engine control strategies and engine after-treatment technologies have significantly improved PM emission levels, motivating the development of new particle measurement instruments and chemical analysis procedures. In this paper, recent research trends are reviewed for physical and chemical PM characterization methods for gasoline and diesel fueled engines under various vehicle certification cycles and real-world driving conditions. The effects of engine technologies, fuels, and engine lubricant oils on exhaust PM morphology and compositions are also discussed.     

Vehicle velocity estimation using effective inertia for an in-wheel electric vehicle

In this study, a vehicle velocity estimation algorithm for an in-wheel electric vehicle is proposed. This algorithm estimates the vehicle velocity using the concept of effective inertia, which is based on the motor torque, the angular velocity of each wheel and vehicle acceleration. Effective inertia is a virtual mass that changes according to the state of a vehicle, such as acceleration, deceleration, turning or driving on a low friction road. The performance of the proposed vehicle velocity estimation algorithm was verified in various conditions that included straight driving, circle driving and low friction road driving using the in-wheel electric vehicle that was equipped with an in-wheel system in each of its rear wheels.     

Enhancing the competitiveness of Korea’s container shipping industry through structural improvements

ABSTRACT

After the collapse of Hanjin Shipping in 2016, Korea faced the task of reconstructing its container shipping industry by enhancing the competitiveness of its shipping companies in a rapidly evolving market environment. Responding to this need for policy design, this study first attempts to understand the industry based on the shipping ecosystem, which comprises the following four areas: shipping finance, collection of cargo, acquisition of ships, and partnership among carriers. Second, it lists the structural problems, along with the remedial policy alternatives, that were identified after conducting in-depth interviews with industry experts, which included mid-level managers. Third, it conducts an importance-performance analysis to classify problems according to their importance and performance, followed by an analytic hierarchy process analysis to define the priorities of policy alternatives. Finally, drawing on the empirical results, the paper concludes with suggestions on an integrated policy package for the container shipping industry.     

Calibrating a social-force-based pedestrian walking model based on maximum likelihood estimation

Although various theories have been adopted to develop reliable pedestrian walking models, a limited effort has been made to calibrate them rigorously based on individual trajectories. Most researchers have validated their models by comparing observed and estimated traffic flow parameters such as speed, density, and flow rate, or replaced the validation by visual confirmation of some well-known phenomena such as channelization and platooning. The present study adopted maximum likelihood estimation to calibrate a social-force model based on the observed walking trajectories of pedestrians. The model was assumed to be made up of five components (i.e., inertia, desired direction, leader–follower relationship, collision avoidance, and random error), and their corresponding coefficients represented relative sensitivity. The model also included coefficients for individual-specific characteristics and for a distance-decay relationship between a pedestrian and his/her leaders or colliders. The calibration results varied with the two density levels adopted in the present study. In the case of high density, significant coefficient estimates were found with respect to both the leader–follower relationship and collision avoidance. Collision avoidance did not affect the pedestrian’s walking behavior for the low-density case due to channelization. The distance limit was confirmed, within which a pedestrian is affected by neighbors. At the low-density level, by comparison with women, men were found to more actively follow leaders, and pedestrians walking in a party were found to be less sensitive to the motion of leaders at the high-density level.     

A process-centric ship design management framework

As the concept of concurrent engineering has emerged along with support for optimization techniques, lots of endeavors have been made to apply optimization techniques to real design problems for holistic decision-making. Even if the range of design problems to which optimization is applicable has been extended, most ship designs use an iterative and manual approach due to the difficulties of seamless integration of all related design activities. This paper proposes a process-centric management framework for the preliminary ship design process depending on these approaches. Requirements for the framework are generated based on the features of the ship design process first. The proposed framework consists of both process scheduling and process management parts. Each of these modules is divided into submodules, and the modules and their interactions are elaborated to reflect actual design practice. The designed framework is embodied within a workflow system and its usefulness examined through a pilot project.     

Challenges in Collaborative Governance for Coastal Restoration: Lessons from the Caernarvon River Diversion in Louisiana

In an effort to restore deteriorating coastal wetlands in Breton Sound, Louisiana, a diversion of Mississippi River water into the estuarine ecosystem has been operated at Caernarvon, Louisiana, since 1991. The diversion was implemented after a relatively long collaborative planning process beginning in the 1950s. The Caernarvon Interagency Advisory Committee, an official panel of stakeholders, considers scientific aspects of the freshwater inflow and stakeholder inputs in developing an operational plan, which internalizes stakeholder conflicts, while accomplishing goals of restoring the coastal ecosystem. Even though fishery representatives are committee members, local oyster fishers filed lawsuits in federal and state courts from 1994 through 2005, claiming damages to their oyster beds. These lawsuits were initially successful in state courts but were reversed by the Louisiana Supreme Court. The federal suits were unsuccessful. Following these lawsuits, voters in Louisiana in 2000 amended the State Constitution to protect coastal restoration projects against lawsuits reflecting increase in overall statewide support. Increasing scientific knowledge has contributed significantly to diversion operation. For better collaborative governance, efforts to increase common understanding among stakeholders will be needed, and a process to compensate interests of stakeholders suffering from impacts of restoration projects at an earlier stage should be institutionalized.     

Prediction of steel plate deformation due to triangle heating using the inherent strain method

In a shipyard, line heating and triangle heating are two major processes carried out by skilled workers to form curved plates in various shapes under various heating conditions. There have been many studies on line heating, but triangle heating has rarely been studied owing to its complicated heating process with irregular multiheating paths and highly concentrated heat input. Triangle heating is the most labor-intensive job. Hence, it is essential for most shipyards to study the automation, as well as the improvement, of the triangle heating process in order to increase hull-forming productivity. In this study, a pioneering attempt to simulate triangle heating was made. A circular disk-spring model is proposed as an analysis model for the elastoplastic procedure of triangle heating, and the inherent strain method is also used to analyze the deformation of plates. The results of the simulation were compared with those of experiments and showed good agreement. It is shown that the present approach and the model used in this study are effective and efficient for simulating triangle heating for the steel plate forming process in shipbuilding.     

Co-operative control for regenerative braking and friction braking to increase energy recovery without wheel lock

This paper presents a regenerative braking co-operative control algorithm to increase energy recovery without wheel lock. Considering the magnitude of the braking force available between the tire and road surface, the control algorithm was designed for the regenerative braking force at the front wheel and friction braking force at the rear wheel to be increased following the friction coefficient line. The performance of the proposed regenerative braking co-operative control algorithm was evaluated by the hardware in the loop simulation (HILS) with an electronic wedge brake on its front wheels and an electronic mechanical brake on its rear wheels. The HILS results showed that a proper braking force on the front and rear wheels on a low μ road prevented the lock of the front wheels that was connected to the motor, and maintained the regenerative braking and increased energy recovery.     

Torsion beam axle system design with a multidisciplinary approach

This research proposes an automatic torsion beam axle optimization process with a multidisciplinary approach and generates the optimal torsion design parameters, such as thickness and shape. In order to construct an automatic analysis process, multidisciplinary analysis models, such as modal analysis, roll mode dynamic analysis, and fatigue analysis, were applied in batch mode. To understand the design space, a parametric study using the torsion beam thickness and shape was performed. Considering roll durability and K&C characteristics, the torsion beam axle could be optimized. For the automated design process, a PIDO tool called PIAnO was used. In conclusion, a reduction in the computer-aided simulation time was achieved, and the durability and K&C characteristics of the torsion beam were enhanced by optimizing the thickness and shape.     

Design,implementation, and power estimation of a lab-scale flapping-type turbine

A lab-scale flapping-type turbine with a semi-passive activation mode has been designed and implemented. A non-linear dynamic model, developed in our previous work, is validated by a series of experiments along with computational fluid dynamics (CFD) simulations. Previously, the dynamic model was used only to estimate the dynamic response of a flapping-type turbine. In this work, the applicability of the dynamic model is extended to estimate the hydrodynamic forces, extracted power, and efficiency. It was demonstrated from a comparison of the CFD results and measured values that the dynamic model based on a quasi-steady approach estimates the aforementioned performance parameters of measurements well in cases particularly with a low effective angle of attack, thus demonstrating the usefulness of the dynamic model for a flapping-type turbine at an early stage.