How has Japan become a major economic power, a world leader in the automotive and electronics industries? What is the secret of their success? The consensus has been that, though the Japanese are not particularly innovative, they are exceptionally skilful at imitation, at improving products that already exist. But now two leading Japanese business experts, Ikujiro Nonaka and Hiro Takeuchi, turn this conventional wisdom on its head: Japanese firms are successful, they contend, precisely because they are innovative, because they create new knowledge and use it to produce successful products and technologies. Examining case studies drawn from such firms as Honda, Canon, Matsushita, NEC, 3M, GE, and the U.S. Marines, this book reveals how Japanese companies translate tacit to explicit knowledge and use it to produce new processes, products, and services.

The knowledge-creating company : how Japanese companies create the dynamics of innovation

A field experiment in Yokohama (Japan) reveals that a macroscopic fundamental diagram (MFD) linking space-mean flow, density and speed exists on a large urban area. The experiment used a combination of fixed detectors and floating vehicle probes as sensors. It was observed that when the somewhat chaotic scatter-plots of speed vs. density from individual fixed detectors were aggregated the scatter nearly disappeared and points grouped neatly along a smoothly declining curve. This evidence suggests, but does not prove, that an MFD exists for the complete network because the fixed detectors only measure conditions in their proximity, which may not represent the whole network. Therefore, the analysis was enriched with data from GPS-equipped taxis, which covered the entire network. The new data were filtered to ensure that only full-taxi trips (i.e., representative of automobile trips) were retained in the sample. The space-mean speeds and densities at different times-of-day were then estimated for the whole study area using relevant parts of the detector and taxi data sets. These estimates were still found to lie close to a smoothly declining curve with deviations smaller than those of individual links – and entirely explained by experimental error. The analysis also revealed a fixed relation between the space-mean flows on the whole network, which are easy to estimate given the existence of an MFD, and the trip completion rates, which dynamically measure accessibility. 2008 Elsevier Ltd. All rights reserved.

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Existence of urban-scale macroscopic fundamental diagrams: Some experimental findings

A field experiment in Yokohama (Japan) reveals that a macroscopic fundamental diagram (MFD) linking space-mean flow, density and speed exists on a large urban area. The experiment used a combination of fixed detectors and floating vehicle probes as sensors. It was observed that when the somewhat chaotic scatter-plots of speed vs. density from individual fixed detectors were aggregated the scatter nearly disappeared and points grouped neatly along a smoothly declining curve. This evidence suggests, but does not prove, that an MFD exists for the complete network because the fixed detectors only measure conditions in their proximity, which may not represent the whole network. Therefore, the analysis was enriched with data from GPS-equipped taxis, which covered the entire network. The new data were filtered to ensure that only full-taxi trips (i.e., representative of automobile trips) were retained in the sample. The space-mean speeds and densities at different times-of-day were then estimated for the whole study area using relevant parts of the detector and taxi data sets. These estimates were still found to lie close to a smoothly declining curve with deviations smaller than those of individual links -- and entirely explained by experimental error. The analysis also revealed a fixed relation between the space-mean flows on the whole network, which are easy to estimate given the existence of an MFD, and the trip completion rates, which dynamically measure accessibility.

In this chapter, you will see how the simplex method simplifies when it is applied to a class of optimization problems that are known as “network flow models.” You will also see that if a network flow model has “integer-valued data,” the simplex method finds an optimal solution that is integer-valued.

Flows in Networks

This paper presents a survey of the empirical literature on the effects of climate change and weather conditions on the transport sector. Despite mixed evidence on many issues, several patterns can be observed. On a global scale especially shifts in tourism and agricultural production due to increased temperatures may lead to shifts in passenger and freight transport. The predicted rise in sea levels and the associated increase in frequency and intensity of storm surges and flooding incidences may furthermore be some of the most worrying consequences of climate change, especially for coastal areas. Climate change related shifts in weather patterns might also cause infrastructure disruptions. Clear patterns are that precipitation affects road safety by increasing accident frequency but decreasing severity. Precipitation also increases congestion, especially during peak hours. Furthermore, an increased frequency of low water levels may considerably increase costs of inland waterway transport. Despite these insights, the net impact of climate change on generalised costs of the various transport modes are uncertain and ambiguous, with a possible exception for inland waterway transport.

The impact of climate change and weather on transport: An overview of empirical findings

This study proposes a microscopic pedestrian simulation model for evaluating pedestrian flow. Recently, several pedestrian models have been proposed to evaluate pedestrian flow in crowded situations for the purpose of designing facilities. However, current pedestrian simulation models do not explain the negotiation process of collision avoidance between pedestrians, which can be important for representing pedestrian behaviour in congested situations. This study builds a microscopic model of pedestrian behaviour using a two-player game and assuming that pedestrians anticipate movements of other pedestrians so as to avoid colliding with them. A macroscopic tactical model is also proposed to determine a macroscopic path to a given destination. The results of the simulation model are compared with experimental data and observed data in a railway station. Several characteristics of pedestrian flows such as traffic volume and travel time in multidirectional flows, temporal–spatial collision avoidance behaviour and density distribution in the railway station are reproduced in the simulation.

Microscopic pedestrian simulation model combined with a tactical model for route choice behaviour

This study aims at analyzing drivers' behavior in acquiring and using traffic information in an environment with multiple information sources. Accordingly, information acquisition and reference models are developed in an effort to show the empirical relationship between drivers' reaction to multiple information sources, causal factors latent psychological ones, traffic conditions at the time of traveling and the accuracy of traffic information available. A route choice model is proposed that takes into account the information acquisition and reference process. Model validity is investigated using data collected on the Tokyo Metropolitan Expressway, which has four different types of information sources.

Incorporating an information acquisition process into a route choice model with multiple information sources

This research discusses the formulation and solution algorithm of the reactive dynamic traffic assignment with the link travel time explicitly taking into account the effects of queues under the point queue concept. In the reactive assignment, vehicles are assumed to choose their routes based on present instantaneous travel times. Time dependent many-to-many origin-destination volumes are assumed to be given; that is, the departure times of vehicles from origins are known. We first discuss the formulation of the dynamic assignment so as to satisfy the flow conservation and the First-In-First-Out queue discipline. Then, the reactive assignment is shown to be decomposed with respect to present time, since route choices of vehicles are dependent on the present traffic situation but independent of the past and future traffic condition. An algorithm is finally proposed based upon the decomposition.

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Decomposition of the reactive dynamic assignments with queues for a many-to-many origin-destination pattern

This research extends the dynamic user optimal assignment under the point queue concept so as to deal with physical queues. Given time-dependent many-to-many OD volumes, this paper first shows the formulation of the assignment subject to the flow conservation and the first-in-first-out (FIFO) queue discipline. The optimal condition is then defined and the physical queue propagation based on the kinematic wave theory is discussed. Finally, a solution algorithm is proposed and typical differences between point and physical queue analyses are presented through an example calculation.

Dynamic user optimal assignment with physical queues for a many-to-many OD pattern

Several researchers have analyzed queueing patterns at bottleneck sites on freeways during the morning peak. However, all previous studies have assumed that each commuter passes only one bottleneck during his commuting trip. Here, we consider the possibility that some commuters pass two bottlenecks on their way to work. The objective is to obtain cumulative arrival curves at each of the two bottlenecks, given who passes both bottlenecks and who passes only one, and their desired arrival times at their work places (work starting times). Each commuter using the freeway is assumed to have the same travel cost function which consists of time-dependent costs due to queueing delay (waiting time in a queue) and schedule delay (the time difference between his actual and desired arrival time at the work place). Commuter trips are assigned temporally so as to establish an equilibrium in which each commuter seeks to minimize his travel cost. The queue evolutions illustrate a service priority at the downstream bottle...

Masao Kuwahara

Papers

Microscopic pedestrian simulation model combined with a tactical model for route choice behaviour

Incorporating an information acquisition process into a route choice model with multiple information sources

Decomposition of the reactive dynamic assignments with queues for a many-to-many origin-destination pattern

Dynamic user optimal assignment with physical queues for a many-to-many OD pattern

Equilibrium Queueing Patterns at a Two-Tandem Bottleneck during the Morning Peak