Strong bottom–up effects on phytoplankton community caused by a rainfall during spring and summer in Sagami Bay,Japan

To assess the consequences of bottom-up effects on phytoplankton community composition during the rainy season, phytoplankton levels and environmental factors were monitored daily from 12 April to 22 July 2003 in Sagami Bay, Japan. The relevant environmental factors were analyzed using cross-correlation analyses. Based on time-series analysis, low surface salinity conditions lasting 0 or 2 days after heavy rainfalls resulted in significant nutrient loading, such as dissolved inorganic nitrogen (DIN), into the coastal area. Also, Chlorophyll-a (Chl-a) concentration frequently increased 2 and 6 days after rainfall. Based on the high total Chl-a concentration, the time was divided into three periods, from 1 to 11 May (Period A), 26 May to 9 June (Period B) and 30 June to 22 July (Period C). The phytoplankton assemblages during Period A were dominated by two dinoflagellates, Ceratium furca and Ceratium fusus. Prior to these species blooming, the heterotrophic dinoflagellate Noctiluca scintillans was dominant. During Period B, the phytoplankton communities were dominated primarily by the diatoms Rhizosolenia delicatula, Hemiaulus sinensis and Navicula spp. Finally, Cerataulina dentata, Rhizosolenia spp., Lauderia borealis and Neodelphineis pelagica were dominant during Period C. After increases in phytoplankton abundance, available nitrogen (N) and phosphorous (P) were consumed and exhausted, which were considered a potential cause of the shift in the dominant organisms from large diatoms to pico- and nano-plankton in the low Chl-a environment. In particular, silicate (Si) was not a major limiting factor for phytoplankton production, since the Si:DIN and Si:P ratios clearly demonstrated that there were no any potential stoichiometric Si limitations, and almost all silicate concentrations were > 2.0 µM during this study. Our results reveal that nutrient sources supplied by river discharge are a main cue for strong bottom–up effects on algal bloom succession during the early summer season in Sagami Bay.     

Performance comparison between pedestrian push-button and pre-timed pedestrian crossings at midblock: a Korean case study

Walking has been highlighted as an independent transportation mode as well as an access/egress mode to/from public transit to encourage the use of more sustainable transport systems. However, walking does not seem to have priority over other transportation modes, especially in areas where various modes of movement are in conflict. The pedestrian push-button system seems to be a solution to distribute the right of way. The focus of this study is on the performance issue of the pedestrian push-button. Specifically, this study deals with issues related to mid-block crossings and attempts to answer two questions: whose waiting time is longer at pre-timed and push-button crossings, pedestrians, or vehicles? and which system – pre-timed or push-button – is better in terms of total waiting time? According to our simulation analyses, if the pedestrian flow rate is less than 120, 85, and 70 ped/h for two-, three-, and four-lane roads, respectively, the push-button system is recommended.     

Effects of Test Conditions on Fuel Economy of Gasoline-Powered Vehicle

In this study, the influence on fuel economy testing of gasoline-powered vehicles is evaluated for various test conditions (e.g., laboratory temperature, soaking time, cooling fan, battery charge state, and driving mode tracking). It showed a difference in fuel economy results of approximately 3 % between low (88 %) and high (99 %) battery state of charge conditions because the alternator saving function has a positive effect on fuel economy. Fuel economy testing with laboratory temperature changes gave a slight reduction at 21 °C and slight increase at 29 °C. The cooling fan changes had an almost negligible effect on fuel consumption. The largest fuel economy result varied by 5.2 % in the soft, standard, and rough driving conditions.     

Dynamic analysis of a pantograph-catenary system using absolute nodal coordinates

The dynamic interaction between the catenary and the pantographs of high-speed trains is a very important factor that affects the stable electric power supply. In order to design a reliable current collection system, a multibody simulation model can provide an efficient and economical method to analyze the dynamic behavior of the catenary and pantograph. In this article, a dynamic analysis method for a pantograph-catenary system for a high-speed train is presented, employing absolute nodal coordinates and rigid body reference coordinates. The highly flexible catenary is modeled using a nonlinear continuous beam element, which is based on an absolute nodal coordinate formulation. The pantograph is modeled as a rigid multibody system. The analysis results are compared with experimental data obtained from a running high-speed train. In addition, using a derived system equation of motion, the calculation method for the dynamic stress in the catenary conductor is presented. This study may have significance in providing an example that a structural and multibody dynamics model can be unified into one numerical system.     

Performance Design of an Exhaust Superheater for Waste Heat Recovery of Construction Equipment

Although fuel cost has been the largest portion of annual operating costs of construction equipment, it is possible to save the energy and reduce cost using fuel economy enhancement technology. In this study, an organic Rankine cycle is applied to an excavator in order to recover waste heat, reproduce it into electrical energy, and consequently reduce the fuel consumption by 10 %. A design process was carried out to develop an exhaust gas superheater that recovers the waste heat from exhaust gas through a composite-dimensional thermal flow analysis. A one-dimensional code was developed to perform a size design for the exhaust gas superheater. The ranges for the major design parameters were determined to satisfy the target of the heat recovery, as well as the pressure drop at both fluid sides. Performance analysis was done through onedimensional design code results, which were compared with three-dimensional CFD analysis. By utilizing a 3D commercial code, the arrangement of the tubes was selected and the working fluid pressure drop was reduced through a detailed layout design. The design procedure was verified by a performance evaluation of the prototype, which yielded only a 7 % tolerance in heat recovery.     

Design and implementation of a UPnP-can gateway for automotive environments

In this paper, we propose a universal plug and play (UPnP) — controller area network (CAN) gateway system using UPnP middleware for interoperability between external smart devices and an in-vehicle network. The proposed gateway consists of a UPnP communication device, a CAN communication device, and a device translator layer. In-vehicle devices are not usually IP-based, so we implemented an in-vehicle device manager in the UPnP communication device which is in the gateway. We developed a vehicle simulator to produce real vehicular data for performance analysis. The CAN communication device transmits and receives real-time vehicle data between the real vehicular simulator and external devices through the UPnP. The device translator layer configures a message frame for enabling seamless data input and output between the CAN and UPnP protocols. After implementation, we generated an internal-external service request and tested the result. Finally, we confirmed the service request and operation between external devices and the internal vehicular device. Additionally, for a variety of external device numbers and communication environments, we demonstrated the gateway performance by measuring the round trip time (RTT) for overall service implementation.     

Realization of pmp-based control for hybrid electric vehicles in a backward-looking simulation

Optimal control is generally not possible without information about the future coming up, and it is not easy to obtain an optimal solution even though the information is given a priori. In this paper, a control concept based on Pontryagin’s Minimum Principle (PMP) is introduced as an efficient solution to generate an optimal control trajectory for Hybrid Electric Vehicles (HVEs) when the performance of the vehicles is evaluated on scheduled driving cycles at a simulation level. The main idea of the control concept is to minimize Hamiltonian, which is interpreted as equivalent fuel consumption, and the Hamiltonian is characterized by a co-state, which is interpreted as a weighting factor for the electrical usage. A key aspect of the control problem is that an appropriate initial condition of the co-state is required to satisfy the boundary condition of the problem. In this study, techniques to calculate the Hamiltonian in different hybrid configurations are introduced, and a methodology to look for the initial condition of the co-state is studied, so that the controller is able to realize a desired State Of Charge (SOC) trajectory. To address the issue, we utilize a shooting method with multiple initial conditions based on the concept of the Newton-Raphson method, and all these techniques are realized in a backward looking simulator. The simulation results show that the PMP-based control is a very efficient approach to produce the optimal control trajectory, and the performance is compared to the optimal solution solved by Dynamic Programming (DP).     

Investigation into the development of a bus electrical cooling fan system

Manufacturers of commercial vehicles are facing a substantial increase of heat release into their cooling systems. The main sources for this increase are more stringent emissions leading to new combustion technologies and the increased power of these engines. The total increase in the cooling requirement may be up to 20% over the current level. At the same time, the noise levels must be decreased, and fuel economy has to improve. This forces manufacturers to consider new concepts and optimize the efficiency of the cooling system. A bus engine cooling fan system is one of the main means of vehicular fuel efficiency reduction. This is becoming a major factor in city noise, and the necessity of electromagnetic technical development is very great. This study features a highly effective BLDC motor for engine cooling fans with high effectiveness and low noise, which is most suitable for fan blade technical development and cooling fan performance evaluation technical development.     

Feasibility of using time–space prism to represent available opportunities and choice sets for destination choice models in the context of dynamic urban environments

H?gerstrand??s original framework of time geography and the subsequent time?Cspace prism computational methods form the foundation of a new computational method for potential path areas (PPA) in a realistic representation of dynamic urban environments. In this paper the time?Cspace prism framework is used to assess sensitivity of PPA size to different parameters and to build choice sets for regional destination choice models. We explain the implication of different parameters to choice set formation in a step-wise manner and illustrate not only the complexity of the idea and the high computational demand but also behavioral realism. In this context, this paper tests the feasibility of using constraint-based time?Cspace prism to find the choice sets for a large-scale destination choice model, and identifies a variety of implementation issues. Computational demand is estimated based on a household travel survey for the Southern California Association of Government, and the feasibility of using time?Cspace prisms for destination choice models is assessed with different levels of information on the network and destinations available. The implications of time of day effects and flexibility in scheduling on choice set development due to varying level of service on the network and availability of activity opportunities are discussed and numerically assessed.