Kyushu University Academic Staff Educational and Research Activities Database
List of Reports
Jun Tanimoto Last modified date:2022.04.29

Professor / Department of Advanced Environmental Science and Engineering / Faculty of Engineering Sciences


Reports
1. A Hagishima, J Tanimoto, Field measurements for estimating the convective heat transfer coefficient at building surfaces, BUILDING AND ENVIRONMENT, 10.1016/S0360-1323(03)00033-7, Vol.38, No.7, pp.873-881, 2003.07, To establish a comprehensive and qualitative prediction basis for the convective heat transfer coefficient (CHTC) for various urban canopy surfaces mainly consisting of building envelopes, a series of outdoor experiments were performed. Multi-point measurements of surface heat balance lead to a distribution of the CHTC on an actual building envelope. Several turbulent statistical values acquired at two different sites enabled the development of an experimental equation depicted by non-dimensional numbers that express a relationship between CHTC and wind velocity containing a turbulent factor. An important thing is the fact that the two measuring sites, one a rooftop slab and the other the vertical wall of a test dwelling, have different scales and different surface directions facing the wind. (C) 2003 Elsevier Science Ltd. All rights reserved..
2. A Hagishima, J Tanimoto, Field measurements for estimating the convective heat transfer coefficient at building surfaces, BUILDING AND ENVIRONMENT, 10.1016/S0360-1323(03)00033-7, Vol.38, No.7, pp.873-881, 2003.07, To establish a comprehensive and qualitative prediction basis for the convective heat transfer coefficient (CHTC) for various urban canopy surfaces mainly consisting of building envelopes, a series of outdoor experiments were performed. Multi-point measurements of surface heat balance lead to a distribution of the CHTC on an actual building envelope. Several turbulent statistical values acquired at two different sites enabled the development of an experimental equation depicted by non-dimensional numbers that express a relationship between CHTC and wind velocity containing a turbulent factor. An important thing is the fact that the two measuring sites, one a rooftop slab and the other the vertical wall of a test dwelling, have different scales and different surface directions facing the wind. (C) 2003 Elsevier Science Ltd. All rights reserved..
3. H Fujii, J Tanimoto, Integration of building simulation and agent simulation for exploration to environmentally symbiotic architecture, BUILDING AND ENVIRONMENT, 10.1016/j.buildenv.2004.01.013, Vol.39, No.8, pp.885-893, 2004.08, A method of simulating the interaction between architectural environment and human action in the environment is described. The computational model consists of a model for building simulation, a model for action simulation, and a model to mediate the simulation models. This model is being developed to find the environmentally symbiotic actions and the knowledge and beliefs that people are encouraged to acquire to perform such actions. It might not be possible for the majority of traditional simulation to model an occupant as the individual having desire, belief, and intention. The proposed model may provide a solution to complement the disadvantage. (C) 2004 Published by Elsevier Ltd..
4. J Tanimoto, A Hagishima, P Chimklai, An approach for coupled simulation of building thermal effects and urban climatology, ENERGY AND BUILDINGS, 10.1016/j.enbuild.2004.01.019, Vol.36, No.8, pp.781-793, 2004.08, The computer software AUSSSM TOOL, originating from the methodology of the revised-architectural-urban-soil-simultaneous simulation model (revised-AUSSSM), was developed by adopting the graphical user interface (GUI) features to support users, who can use the interactive computer display for parameter settings, simulating, visualizing, and reporting the numerical calculation results instead of complicated programming. The purpose of the AUSSSM TOOL is to determine quantitative parameters such as air temperature, exhaustive heat from air conditioning systems, energy heat balance, etc. within the urban canopy structure, which data enables the evaluation of effects of urban heat island (UHI) in concrete terms useful to urban planners, architects, engineers, and so forth in the field of urban climatology involving building scale. In addition to conducting a full numerical simulation, in order to simplify a comparison among complex factors influencing UHI, numerical experiments based on Taguchi design of experiment theory (DOE) were carried out. The results of the numerical experiments were stored in a database and ready to be instantly grasped by any inexperienced user corresponding to their specified conditions. This paper describes the fundamental method of the revised-AUSSSM, the objectives of related software development, and the structures of the AUSSSM TOOL and the techniques comprising its algorithm to present the numerical simulation results in particular. (C) 2004 Published by Elsevier B.V..
5. J Tanimoto, A Hagishima, P Chimklai, An approach for coupled simulation of building thermal effects and urban climatology, ENERGY AND BUILDINGS, 10.1016/j.enbuild.2004.01.019, Vol.36, No.8, pp.781-793, 2004.08, The computer software AUSSSM TOOL, originating from the methodology of the revised-architectural-urban-soil-simultaneous simulation model (revised-AUSSSM), was developed by adopting the graphical user interface (GUI) features to support users, who can use the interactive computer display for parameter settings, simulating, visualizing, and reporting the numerical calculation results instead of complicated programming. The purpose of the AUSSSM TOOL is to determine quantitative parameters such as air temperature, exhaustive heat from air conditioning systems, energy heat balance, etc. within the urban canopy structure, which data enables the evaluation of effects of urban heat island (UHI) in concrete terms useful to urban planners, architects, engineers, and so forth in the field of urban climatology involving building scale. In addition to conducting a full numerical simulation, in order to simplify a comparison among complex factors influencing UHI, numerical experiments based on Taguchi design of experiment theory (DOE) were carried out. The results of the numerical experiments were stored in a database and ready to be instantly grasped by any inexperienced user corresponding to their specified conditions. This paper describes the fundamental method of the revised-AUSSSM, the objectives of related software development, and the structures of the AUSSSM TOOL and the techniques comprising its algorithm to present the numerical simulation results in particular. (C) 2004 Published by Elsevier B.V..
6. P Chimklai, A Hagishima, J Tanimoto, A computer system to support Albedo Calculation in urban areas, BUILDING AND ENVIRONMENT, 10.1016/j.buildenv.2004.02.006, Vol.39, No.10, pp.1213-1221, 2004.10, The Albedo Calculation Model (ACM) has been developed to provide the simulation of albedos within three-dimensional urban structures. The model takes into account urban configurations and a change of solar positions, as well as the effects of multiple reflections and shading in an urban canopy. In order to perform a systematic analysis for the effect of various factors on albedo of surfaces, a large scale numerical experiment has been conducted. The model description and experiment results of albedo characteristics are clarified in this paper. In addition, the development of two associated GUI (graphical user interface)-based applications, Albedo Calculator and Albedo Viewer is also introduced. (C) 2004 Elsevier Ltd. All rights reserved..
7. P Chimklai, A Hagishima, J Tanimoto, A computer system to support Albedo Calculation in urban areas, BUILDING AND ENVIRONMENT, 10.1016/j.buildenv.2004.02.006, Vol.39, No.10, pp.1213-1221, 2004.10, The Albedo Calculation Model (ACM) has been developed to provide the simulation of albedos within three-dimensional urban structures. The model takes into account urban configurations and a change of solar positions, as well as the effects of multiple reflections and shading in an urban canopy. In order to perform a systematic analysis for the effect of various factors on albedo of surfaces, a large scale numerical experiment has been conducted. The model description and experiment results of albedo characteristics are clarified in this paper. In addition, the development of two associated GUI (graphical user interface)-based applications, Albedo Calculator and Albedo Viewer is also introduced. (C) 2004 Elsevier Ltd. All rights reserved..
8. J Tanimoto, A Hagishima, State transition probability for the Markov Model dealing with on/off cooling schedule in dwellings, ENERGY AND BUILDINGS, 10.1016/j.enbuild.2004.02.002, Vol.37, No.3, pp.181-187, 2005.03, We gathered field measurement data on five familial and three single dwellings during summer 2000 by deploying numerous handy type hygrothermal meters with self-recording functions to measure room air, globe and outdoor air temperatures. These measurements led to conclusions on the probability of turning on an air conditioning system versus indoor globe temperature and the ongoing probability of air conditioning versus outdoor temperature. This analysis was transformed into state transition probability functions, i.e. shifting from the off to on state and from the on to off state. Identifying these state transition probability functions is an important first step in applying the Markov Model to on/off state analysis for air conditioning systems, which is one of the significant approaches for dealing with the stochastic thermal load for HVAC system. The obtained state transition probability functions should help immeasurably in determining effective schedules for air conditioning operation from inhabitant occupancy schedules. (C) 2004 Elsevier B.V. All rights reserved..
9. A Hagishima, J Tanimoto, Investigations of urban surface conditions for urban canopy model, BUILDING AND ENVIRONMENT, 10.1016/j.buildenv.2004.08.010, Vol.40, No.12, pp.1638-1650, 2005.12, The authors carried out several investigations to clarify the features of urban surface conditions in the urban canopy Model (UCM). The authors first conducted field investigations regarding the solar reflectance of urban surfaces. First, the wall reflectance and the proportion of the glazing area were measured in several urban areas. The relationship between the solar reflectance of road and traffic density is clarified based on the outdoor measurement and the field survey. It is also presented that the reflectance of the building rooftop varies significantly depending on building use and the influence of machinery in the area of the HVAC.
The authors secondly investigated the height of released anthropogenic heat from the HVAC system based on a field survey and a database of HVAC systems provided by certain journals. From these investigations, it is presented that the type of HVAC system and the height of released anthropogenic heat vary with the building scale. Finally, an investigation of urban geometric figures was conducted using GIS data from Tokyo and Fukuoka in Japan. The vertical distribution features of both the roughness volume density and the building wall area density were classified according to the gross ratio of building volume. (c) 2004 Elsevier Ltd. All rights reserved..
10. A Hagishima, J Tanimoto, K Narita, Intercomparisons of experimental convective heat transfer coefficients and mass transfer coefficients of urban surfaces, BOUNDARY-LAYER METEOROLOGY, 10.1007/s10546-005-2078-7, Vol.117, No.3, pp.551-576, 2005.12, The convective heat transfer coefficient (CHTC) of an urban canopy is a crucial parameter for estimating the turbulent heat flux in an urban area. We compared recent experimental research on the CHTC and the mass transfer coefficient (MTC) of urban surfaces in the field and in wind tunnels. Our findings are summarised as follows.
(1)In full-scale measurements on horizontal building roofs, the CHTC is sensitive to the height of the reference wind speed for heights below 1.5 m but is relatively independent of roof size.
(2)In full-scale measurements of vertical building walls, the dependence of the CHTC on wind speed is significantly influenced by the choice of the measurement position and wall size. The CHTC of the edge of the building wall is much higher than that near the centre.
(3) In spite of differences of the measurement methods, wind-tunnel experiments of the MTC give similar relations between the ratio of street width to canopy height in the urban canopy. Moreover, this relationship is consistent with known properties of the flow regime of an urban canopy.
(4) Full-scale measurements on roofs result in a non-dimensional CHTC several tens of times greater than that in scale-model experiments with the same Reynolds number.
Although there is some agreement in the measured values, our overall understanding of the CHTC remains too low for accurate modelling of urban climate..
11. J Tanimoto, Environmental dilemma game to establish a sustainable society dealing with an emergent value system, PHYSICA D-NONLINEAR PHENOMENA, 10.1016/j.physd.2004.09.016, Vol.200, No.1-2, pp.1-24, 2005.01, To induce whether we can obtain a sustainable society by shifting our paradigm from the materialistic to the eco-conscientious, we established a multi-agent simulation model. The model primarily featured a dilemma structure encouraged by a conflict between each agent's private desire to earn more and the need for environmental conservation. Another important feature is that the model has two evolutionary layers. The subordinate layer is a learning system comprised of a finite state machine (FSM) and a genetic algorithm (GA) primarily, which is carried with each individual agent to determine his/her next behavior and how much he/she must earn to maximize an individual fitness function. The supra layer is the so-called value system, the gene pool of which is shared within the society. The value system stipulates an agent's fitness function, which in turn affects the agent's behavior. The value system of each agent was set up to be entirely ego-oriented at the beginning of the simulation episode. A numerical experiment based on the model reveals a scene in which, under a certain condition related to assumptions of the value system, a group of agents undergoes a paradigm shift from the ego-oriented materialism to the eco-conscious sustainable society. The key condition is a latent existence of several values that ultimately lead to sustainability, even though they do not work at all at the beginning of the episode. In terms of the evolutionary game theory, this implies that changing game structure on the way of a simulation episode by transforming the fitness function seems to be much powerful measures for the emergent collective cooperation among the agents than ordinal options to support cooperation. In addition, we made a detailed analysis on how assumed agents have obtained a sustainable value system. Each agent has an individual decision-making process based on the input with a learning mechanism. We focus here on two types of learning system, the finite state machine (FSM) plus genetic algorithm (GA), and profit shearing (PS). Observation of the generative trails of FSM and the value table of PS lead us to a profound understanding of what kind of inception triggers the emergence of a sustainable society. (C) 2004 Elsevier B. V. All rights reserved..
12. Jun Tanimoto, Hiroki Sagara, Relationship between dilemma occurrence and the existence of a weakly dominant strategy in a two-player symmetric game, BIOSYSTEMS, 10.1016/j.biosystems.2006.07.005, Vol.90, No.1, pp.105-114, 2007.07, Defining the dilemma game by the proposition, A game cannot sustain an increase (of cooperation strategy in its strategy distribution, we deduced that the substance of a dilemma can be expressed by a productive summation of the staticfactor and the dynamic factor independently. A static factor is an element of the game's structure that influences a possible dilemma, which relates to a game's structural deviation from a situation where the cooperation strategy can be weakly dominant over other strategies. In contrast, a dynamic factor refers to a strategy distribution's influence on the dilemma by affecting the game dynarnics. In a 2 x 2 game, the existence of a dilemma can be determined only by a static factor. That is, whether or not a dilemma occurs is related only to the structural effect of the game. On the other hand, in a more-than-two-strategies game, both static and dynamic factors determine the occurrence of a dilemma, and the static factor cannot solely explain the occurrence of a dilemma. (c) 2006 Elsevier Ireland Ltd. All rights reserved..
13. Jun Tanimoto, Hiroki Sagara, Relationship between dilemma occurrence and the existence of a weakly dominant strategy in a two-player symmetric game, BIOSYSTEMS, 10.1016/j.biosystems.2006.07.005, Vol.90, No.1, pp.105-114, 2007.07, Defining the dilemma game by the proposition, A game cannot sustain an increase (of cooperation strategy in its strategy distribution, we deduced that the substance of a dilemma can be expressed by a productive summation of the staticfactor and the dynamic factor independently. A static factor is an element of the game's structure that influences a possible dilemma, which relates to a game's structural deviation from a situation where the cooperation strategy can be weakly dominant over other strategies. In contrast, a dynamic factor refers to a strategy distribution's influence on the dilemma by affecting the game dynarnics. In a 2 x 2 game, the existence of a dilemma can be determined only by a static factor. That is, whether or not a dilemma occurs is related only to the structural effect of the game. On the other hand, in a more-than-two-strategies game, both static and dynamic factors determine the occurrence of a dilemma, and the static factor cannot solely explain the occurrence of a dilemma. (c) 2006 Elsevier Ireland Ltd. All rights reserved..
14. Jun Tanimoto, Promotion of cooperation by payoff noise in a 2x2 game, PHYSICAL REVIEW E, 10.1103/PhysRevE.76.041130, Vol.76, No.4, p.#041130, 2007.10, A series of numerical simulations of a 2x2 symmetric game on a network examined whether payoff matrix noise promotes cooperation, as reported initially by Perc [New J. Phys. 8, 22 (2006)]. Agents have no memory (they offer cooperation, C, or defection, D). We assume that the network is time invariable. The effect of payoff matrix noise (PMN) is measured by a simulated payoff difference between a normal network game and a network game with PMN. The effect of PMN appears only when a local strategy adaptation is implemented (for example, a network game with imitation dynamics). The influence of PMN becomes more significant with a larger stochastic deviation, and less significant in a larger degree network. One reason for PMN's effectiveness is the local strategy adaptation mechanism, which helps both the preservation and fixation of C agents, and not that the payoff matrix noise makes a dilemma game into a Trivial (dilemma-free) game..
15. Jun Tanimoto, Promotion of cooperation by payoff noise in a 2 × 2 game, Physical Review E, 10.1103/PhysRevE.76.041130, Vol.76, No.4, p.#041130, 2007.10.
16. Aya Hagishima, Ken-ich Narita, Jun Tanimoto, Field experiment on transpiration from isolated urban plants, HYDROLOGICAL PROCESSES, 10.1002/hyp.6681, Vol.21, No.9, pp.1217-1222, 2007.04, The effect of pot plant density on plant transpiration rate was examined in a series of field experiments. Three spatial densities were created using 203 nearly homogeneous pot plants; the ratios of plant separation to plant height were 0.25, 0-5, and 3 for the 'high,' 'medium,' and 'low' groups respectively. The daily transpiration rate of 55 pot plants was measured for 28 days. During that period, the plants were randomly rotated each day to statistically eliminate individual characteristics and to successfully ascertain the effect of plant spatial density on the transpiration rate. As a best-case scenario, the soil for each plant was saturated at the start of each experiment. The results showed that the transpiration rate of potted plants in the 'low' group was about 1-5 times greater than that of the 'high' group. On the basis of the transpiration rate per unit of vegetation area projected on a horizontal plain, which is a general index used in meteorological modeling, the plants in the 'low' group evaporated 2.7 times as much water as those in the centre of the 'high' group. These results indicate the need for modified models that can consider the relative increase in evapotranspiration from vegetation in small-size plants or low spatial density of vegetation to estimate latent heat flux in urban areas. Copyright (c) 2007 John Wiley & Sons, Ltd..
17. Aya Hagishima, Ken-ich Narita, Jun Tanimoto, Field experiment on transpiration from isolated urban plants, HYDROLOGICAL PROCESSES, 10.1002/hyp.6681, Vol.21, No.9, pp.1217-1222, 2007.04, The effect of pot plant density on plant transpiration rate was examined in a series of field experiments. Three spatial densities were created using 203 nearly homogeneous pot plants; the ratios of plant separation to plant height were 0.25, 0-5, and 3 for the 'high,' 'medium,' and 'low' groups respectively. The daily transpiration rate of 55 pot plants was measured for 28 days. During that period, the plants were randomly rotated each day to statistically eliminate individual characteristics and to successfully ascertain the effect of plant spatial density on the transpiration rate. As a best-case scenario, the soil for each plant was saturated at the start of each experiment. The results showed that the transpiration rate of potted plants in the 'low' group was about 1-5 times greater than that of the 'high' group. On the basis of the transpiration rate per unit of vegetation area projected on a horizontal plain, which is a general index used in meteorological modeling, the plants in the 'low' group evaporated 2.7 times as much water as those in the centre of the 'high' group. These results indicate the need for modified models that can consider the relative increase in evapotranspiration from vegetation in small-size plants or low spatial density of vegetation to estimate latent heat flux in urban areas. Copyright (c) 2007 John Wiley & Sons, Ltd..
18. Jun Tanimoto, Does a tag system effectively support emerging cooperation?, JOURNAL OF THEORETICAL BIOLOGY, 10.1016/j.jtbi.2007.03.033, Vol.247, No.4, pp.756-764, 2007.08, This paper investigates whether the so-called Tag Systems support emerging cooperation with respect to 2 x 2 games. The Tag System, initially proposed by Riolo et al. [2001. Evolution of cooperation without reciprocity. Nature 414, 441-4431, gives each agent both a Tag and Tol defined by [0, 1] real numbers. Tol is a tolerance for recognizing an opponent as a company. Both Tag and Tol are assumed to be evolving. Results show that the tag's effectiveness depends on whether the AllD strategy is allowed in the system. Allowing AIID implies that green beard effect does not work in the system. Thus, (1) the tag's effectiveness is more meager than that reported by Riolo et al., (2) the Tag System can use alternating reciprocity more effectively than the analytic solution in a Hero game-, (3) a system using a 2D tag space supports cooperation more effectively than the usual Tag System. (c) 007 Elsevier Ltd. All rights reserved..
19. Jun Tanimoto, Does a tag system effectively support emerging cooperation?, Journal of Theoretical Biology, 10.1016/j.jtbi.2007.03.033, Vol.247, No.4, pp.756-764, 2007.08, This paper investigates whether the so-called Tag Systems support emerging cooperation with respect to 2×2 games. The Tag System, initially proposed by Riolo et al. [2001. Evolution of cooperation without reciprocity. Nature 414, 441-443], gives each agent both a Tag and Tol defined by [0,1] real numbers. Tol is a tolerance for recognizing an opponent as a company. Both Tag and Tol are assumed to be evolving. Results show that the tag's effectiveness depends on whether the AllD strategy is allowed in the system. Allowing AllD implies that green beard effect does not work in the system. Thus, (1) the tag's effectiveness is more meager than that reported by Riolo et al., (2) the Tag System can use alternating reciprocity more effectively than the analytic solution in a Hero game
(3) a system using a 2D tag space supports cooperation more effectively than the usual Tag System. © 2007 Elsevier Ltd. All rights reserved..
20. Jun Tanimoto, Dilemma solving by the coevolution of networks and strategy in a 2x2 game, PHYSICAL REVIEW E, 10.1103/PhysRevE.76.021126, Vol.76, No.2, p.#021126, 2007.08, A 2x2 game model implemented by a coevolution mechanism of both networks and strategy, inspired by the work of Zimmermann and Eguiluz [Phys. Rev. E72, 056118 (2005)] is established. Network adaptation is the manner in which an existing link between two agents is destroyed and how a new one is established to replace it. The strategy is defined as whether an agent offers cooperation (C) or defection (D). Both the networks and strategy are synchronously renovated in a simulation time step. A series of numerical experiments, considering various 2x2 game structures, reveals that the proposed coevolution mechanism can solve dilemmas in several game classes. The effect of solving a dilemma means mutual-cooperation reciprocity (R reciprocity), which is brought about by emerging several cooperative hub agents who have plenty of links. This effect can be primarily observed in game classes of the prisoner's dilemma and stag hunt. The coevolution mechanism, however, seems counterproductive for game classes of leader and hero, where the alternating reciprocity (ST reciprocity) is meaningful..
21. Jun Tanimoto, Dilemma solving by the coevolution of networks and strategy in a 2×2 game, Physical Review E - Statistical, Nonlinear, and Soft Matter Physics, 10.1103/PhysRevE.76.021126, Vol.76, No.2, p.#021126, 2007.08, A 2×2 game model implemented by a coevolution mechanism of both networks and strategy, inspired by the work of Zimmermann and Eguiluz [Phys. Rev. E72, 056118 (2005)] is established. Network adaptation is the manner in which an existing link between two agents is destroyed and how a new one is established to replace it. The strategy is defined as whether an agent offers cooperation (C) or defection (D). Both the networks and strategy are synchronously renovated in a simulation time step. A series of numerical experiments, considering various 2×2 game structures, reveals that the proposed coevolution mechanism can solve dilemmas in several game classes. The effect of solving a dilemma means mutual-cooperation reciprocity (R reciprocity), which is brought about by emerging several cooperative hub agents who have plenty of links. This effect can be primarily observed in game classes of the prisoner's dilemma and stag hunt. The coevolution mechanism, however, seems counterproductive for game classes of leader and hero, where the alternating reciprocity (ST reciprocity) is meaningful. © 2007 The American Physical Society..
22. Jun Tanimoto, Differences in dynamics between discrete strategies and continuous strategies in a multi-player game with a linear payoff structure, BIOSYSTEMS, 10.1016/j.biosystems.2006.12.008, Vol.90, No.2, pp.568-572, 2007.09, A deductive analysis concerning replicator dynamics proved that a continuous strategy game (in which a player chooses an arbitrary real number between [0, 1] as a cooperative fraction) has the same equilibrium as a discrete strategy game (in which a player chooses only C or D), which has the same linear payoff structure as a continuous strategy game. The deduction is shown for two-player and multi-player games. (C) 2007 Elsevier Ireland Ltd. All rights reserved..
23. Jun Tanimoto, Differences in dynamics between discrete strategies and continuous strategies in a multi-player game with a linear payoff structure, BioSystems, 10.1016/j.biosystems.2006.12.008, Vol.90, No.2, pp.568-572, 2007.09, A deductive analysis concerning replicator dynamics proved that a continuous strategy game (in which a player chooses an arbitrary real number between [0, 1] as a cooperative fraction) has the same equilibrium as a discrete strategy game (in which a player chooses only C or D), which has the same linear payoff structure as a continuous strategy game. The deduction is shown for two-player and multi-player games. © 2007 Elsevier Ireland Ltd. All rights reserved..
24. Jun Tanimoto, Hiroki Sagara, A study on emergence of alternating reciprocity in a 2 x 2 game with 2-length memory strategy, BIOSYSTEMS, 10.1016/j.biosystems.2007.03.001, Vol.90, No.3, pp.728-737, 2007.11, It is recognized that bilateral cooperation (C), a reward-state in other words, emergently comes up in a 2 x 2 prisoner's dilemma. game, if you assume a strategy set with a memory concept. Also observed is a mixture state of cooperation (C) and defect (D), saint- and temptation-state in other words, to obtain a higher payoff than R (R reciprocity) in a hero or leader game that is a chicken-type dilemma game; this phenomenon is called alternating reciprocity (AR) or ST reciprocity. Observing a holistic 2 x 2 game world including trivial games and various dilemma games, where 2-length memory and infinite interactions are assumed, the paper reports on the specific mechanism of AR. It is observed there are three different phases relating to AR, which can be explained by the stress of the dilemma. (c) 2007 Elsevier Ireland Ltd. All rights reserved..
25. Jun Tanimoto, Hiroki Sagara, A study on emergence of alternating reciprocity in a 2 x 2 game with 2-length memory strategy, BIOSYSTEMS, 10.1016/j.biosystems.2007.03.001, Vol.90, No.3, pp.728-737, 2007.11, It is recognized that bilateral cooperation (C), a reward-state in other words, emergently comes up in a 2 x 2 prisoner's dilemma. game, if you assume a strategy set with a memory concept. Also observed is a mixture state of cooperation (C) and defect (D), saint- and temptation-state in other words, to obtain a higher payoff than R (R reciprocity) in a hero or leader game that is a chicken-type dilemma game; this phenomenon is called alternating reciprocity (AR) or ST reciprocity. Observing a holistic 2 x 2 game world including trivial games and various dilemma games, where 2-length memory and infinite interactions are assumed, the paper reports on the specific mechanism of AR. It is observed there are three different phases relating to AR, which can be explained by the stress of the dilemma. (c) 2007 Elsevier Ireland Ltd. All rights reserved..
26. Jun Tanimoto, A study of indirect reciprocity involving a reputation system or a simple tag system in a one-shot, multi-player game, BIOSYSTEMS, 10.1016/j.biosystems.2007.05.002, Vol.90, No.3, pp.856-869, 2007.11, The possibility of the evolution of cooperation backed by indirect reciprocity (IDR) in a one-shot, multi-player game is investigated focusing on two mechanisms. First of all, the reputation system with image score (RS with IS), as proposed by Nowak and Sigmund [Nowak, M.A., Sigmund, K., 1998. Evolution of indirect reciprocity by image scoring. Nature 393, 573-577], is investigated in various game structures. A numerical experiment demonstrates that the RS with IS is a robust mechanism for the support of IDR in various dilemma games, but whose effectiveness decreases with an increase in the number of players in a game. It is fair to say that the RS is an information mapping function to relate between player's cooperative fraction on his action and IS. As the second mechanism, a simple tag system which could be applicable to animals having no cognitive complexity is considered to support IDR. Computer simulations of the tag system's strategy for invading a population initially consisting of AllD, AllC, and Random strategies suggest several novel facts. The Tag strategy with plausible crossover and mutation probabilities can only invade to settle down if the game structure is not Trivial and contains a moderate dilemma. The Tag strategy's evolutionary competition takes place mainly in the presence of the AllD strategy. During the competition, the Tag strategy frequently metamorphoses to shake off the AllD strategy, but stops after winning in order to avoid a shrinking payoff due to fragmentation. (c) 2007 Elsevier Ireland Ltd. All rights reserved..
27. Jun Tanimoto, What initially brought about communications?, BioSystems, 10.1016/j.biosystems.2007.12.001, Vol.92, No.1, pp.82-90, 2008.04, This paper reports an intelligent agent equipped with two-layer finite state machines (FSMs) that can communicate by turning lighting on and off, leading to social cooperation that solves the dilemma situation, modeled by a one-shot 2 × 2 game. This communication between two gaming agents can be observed in hero- and leader-type dilemma games, where alternating reciprocity, repeating cooperation (C)-defeat (D) after D-C, is the equal pareto optimum instead of a sequence of mutual cooperation that is the equal pareto optimum for a prisoner's dilemma (PD) game. © 2008 Elsevier Ireland Ltd. All rights reserved..
28. Jun Tanimoto, What initially brought about communications?, BIOSYSTEMS, 10.1016/j.biosystems.2007.12.001, Vol.92, No.1, pp.82-90, 2008.04, This paper reports an intelligent agent equipped with two-layer finite state machines (FSMs) that can communicate by turning lighting on and off, leading to social cooperation that solves the dilemma situation, modeled by a one-shot 2 x 2 game. This communication between two gaming agents can be observed in hero- and leader-type dilemma games, where alternating reciprocity, repeating cooperation (Q-defeat (D) after D-C, is the equal pareto optimum instead of a sequence of mutual cooperation that is the equal pareto, optimum for a prisoner's dilemma (PD) game. (C) 2008 Elsevier Ireland Ltd. All rights reserved..
29. Jun Tanimoto, Aya Hagishima, Hiroki Sagara, Validation of methodology for utility demand prediction considering actual variations in inhabitant behaviour schedules, Journal of Building Performance Simulation, 10.1080/19401490701868471, Vol.1, No.1, pp.31-42, 2008.01, A data set of myriad and time-varying inhabitant behaviour schedules with a 15-min time resolution, generated by the authors in a previous study, is validated through a comparison analysis. The key idea of generating a set of raw schedule data from the restricted statistical information is called the ‘generate and kill’ concept, which is commonly used in the fields of artificial intelligence and multi-agent simulation. In the present study, we show three comparisons. The first and second compare the estimated demand with a time series of measured utility demand. These comparisons indicate that the generated data and the algorithm, as described by the authors, have the required robustness. Another comparison between the estimate and the annually averaged daily water demand of a residential area, consisting of 9327 residences, also shows an acceptable consistency..
30. Jun Tanimoto, Aya Hagishima, Hiroki Sagara, Validation of methodology for utility demand prediction considering actual variations in inhabitant behaviour schedules, Journal of Building Performance Simulation, 10.1080/19401490701868471, Vol.1, No.1, pp.31-42, 2008.01, A data set of myriad and time-varying inhabitant behaviour schedules with a 15-min time resolution, generated by the authors in a previous study, is validated through a comparison analysis. The key idea of generating a set of raw schedule data from the restricted statistical information is called the ‘generate and kill’ concept, which is commonly used in the fields of artificial intelligence and multi-agent simulation. In the present study, we show three comparisons. The first and second compare the estimated demand with a time series of measured utility demand. These comparisons indicate that the generated data and the algorithm, as described by the authors, have the required robustness. Another comparison between the estimate and the annually averaged daily water demand of a residential area, consisting of 9327 residences, also shows an acceptable consistency..
31. Jun Tanimoto, Aya Hagishima, Hiroki Sagara, A methodology for peak energy requirement considering actual variation of occupants' behavior schedules, BUILDING AND ENVIRONMENT, 10.1016/j.buildenv.2006.06.034, Vol.43, No.4, pp.610-619, 2008.04, A novel methodology to accurately estimate the cooling demand in residential units is proposed, as a means of providing a better assessment of urban heat-island effects attributable to the use of residential air-conditioning units. The methodology integrates probabilistic variations in occupant behavior, which is shown to be a significant factor in estimated residential cooling requirements. The methodology consists of two key features. The first is an algorithm that generates short-term events that are likely to occur in a residential context, based on published data on occupant behavior. The second is a Monte Carlo approach to cooling load calculations based on stochastic variations in these short-term events and in the consequent likelihood of switching air-conditioning on or off. (C) 2006 Elsevier Ltd. All rights reserved..
32. Jun Tanimoto, Aya Hagishima, Hiroki Sagara, A methodology for peak energy requirement considering actual variation of occupants’ behavior schedules, Building and Environment, 10.1016/j.buildenv.2006.06.034, Vol.43, No.4, pp.610-619, 2008.04.
33. Jun Tanimoto, Promotion of cooperation through co-evolution of networks and strategy in a 2 x 2 game, PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS, 10.1016/j.physa.2008.11.023, Vol.388, No.6, pp.953-960, 2009.03, A 2 x 2 game model implemented by co-evolution of both networks and strategies is established. An existing link between two agents is killed through network adaptation, which then establishes a new link to replace it. Strategy is defined as an offer of "cooperation" (C) or "defection" (D) by an agent. Both networks and strategies are synchronously renovated in each simulation time step. After killing the link with the most disadvantageous neighbor, we consider network adaptations that involve rewiring to (1) a randomly selected agent, (2) a proportionally selected agent (through a roulette selection process based on the degrees of respective agents), (3) an agent randomly selected among a set of neighbors of the neighbors, excluding the most disadvantageous neighbor. Several numerical experiments considering various 2 x 2 game classes, including Prisoner's Dilemma (PD), Chicken, Leader, and Hero, reveal that the proposed co-evolution mechanism can solve dilemmas in the PD game class. The result of solving a dilemma is the development of mutual-cooperation reciprocity (R reciprocity), which arises through the emergence of several cooperative hub agents, which have many links in a heterogeneous and assortative social network. However, the co-evolution mechanism seems counterproductive in the case of the Leader and Hero game classes, where alternating reciprocity (ST reciprocity) is more demanding. It is also suggested that the assortative and cluster coefficients of a network affect the emergence of cooperation for R reciprocity. (C) 2008 Elsevier B.V. All rights reserved..
34. Jun Tanimoto, Promotion of cooperation through co-evolution of networks and strategy in a 2 × 2 game, Physica A: Statistical Mechanics and its Applications, 10.1016/j.physa.2008.11.023, Vol.388, No.6, pp.953-960, 2009.03, A 2×2 game model implemented by co-evolution of both networks and strategies is established. An existing link between two agents is killed through network adaptation, which then establishes a new link to replace it. Strategy is defined as an offer of "cooperation" (C) or "defection" (D) by an agent. Both networks and strategies are synchronously renovated in each simulation time step. After killing the link with the most disadvantageous neighbor, we consider network adaptations that involve rewiring to (1) a randomly selected agent, (2) a proportionally selected agent (through a roulette selection process based on the degrees of respective agents), (3) an agent randomly selected among a set of neighbors of the neighbors, excluding the most disadvantageous neighbor. Several numerical experiments considering various 2×2 game classes, including Prisoner's Dilemma (PD), Chicken, Leader, and Hero, reveal that the proposed co-evolution mechanism can solve dilemmas in the PD game class. The result of solving a dilemma is the development of mutual-cooperation reciprocity (R reciprocity), which arises through the emergence of several cooperative hub agents, which have many links in a heterogeneous and assortative social network. However, the co-evolution mechanism seems counterproductive in the case of the Leader and Hero game classes, where alternating reciprocity (ST reciprocity) is more demanding. It is also suggested that the assortative and cluster coefficients of a network affect the emergence of cooperation for R reciprocity. © 2008 Elsevier B.V. All rights reserved..
35. J. T. Oliveira, Aya Hagishima, Jun Tanimoto, Estimation of passive cooling efficiency for environmental design in Brazil, ENERGY AND BUILDINGS, 10.1016/j.enbuild.2009.02.006, Vol.41, No.8, pp.809-813, 2009.08, An estimation of passive cooling techniques was conducted for 14 cities in Brazil, using a fairly accurate algorithm that accounts for heat conduction, convection, radiation, and evaporation; this was done to determine the amount of heat gain/loss of room air, defined as a particular quantitative index for passive techniques. Heat gains and losses were calculated for four envelope conditions - namely, insulated, high-albedo, wet surface, and a combination of the previous two - and compared to a case assumed to be the standard condition. A conclusion drawn was that a passive design is efficient in decreasing the need for cooling in typical dwellings in Brazil; solutions should differ with regional climate characteristics. In semi-arid areas, evaporative cooling showed the best results. Reduced heat gain was found during the warm seasons for all cities, along with increased heat gain during the cool seasons for mid-latitude cities. in particular, a combination of high-albedo enveloping and evaporation can greatly decrease heat gain in building walls. High-albedo surfaces in the sub-tropical areas found in southern Brazil are more efficient. It is suggested that passive techniques should be conceived in such a way so as to work during the cooling season and be disabled during mild ones. (C) 2009 Elsevier B.V. All rights reserved..
36. J. T. Oliveira, Aya Hagishima, Jun Tanimoto, Estimation of passive cooling efficiency for environmental design in Brazil, ENERGY AND BUILDINGS, 10.1016/j.enbuild.2009.02.006, Vol.41, No.8, pp.809-813, 2009.08, An estimation of passive cooling techniques was conducted for 14 cities in Brazil, using a fairly accurate algorithm that accounts for heat conduction, convection, radiation, and evaporation; this was done to determine the amount of heat gain/loss of room air, defined as a particular quantitative index for passive techniques. Heat gains and losses were calculated for four envelope conditions - namely, insulated, high-albedo, wet surface, and a combination of the previous two - and compared to a case assumed to be the standard condition. A conclusion drawn was that a passive design is efficient in decreasing the need for cooling in typical dwellings in Brazil; solutions should differ with regional climate characteristics. In semi-arid areas, evaporative cooling showed the best results. Reduced heat gain was found during the warm seasons for all cities, along with increased heat gain during the cool seasons for mid-latitude cities. in particular, a combination of high-albedo enveloping and evaporation can greatly decrease heat gain in building walls. High-albedo surfaces in the sub-tropical areas found in southern Brazil are more efficient. It is suggested that passive techniques should be conceived in such a way so as to work during the cooling season and be disabled during mild ones. (C) 2009 Elsevier B.V. All rights reserved..
37. Atsuo Yamauchi, Jun Tanimoto, Aya Hagishima, Hiroki Sagara, Dilemma game structure observed in traffic flow at a 2-to-1 lane junction, PHYSICAL REVIEW E, 10.1103/PhysRevE.79.036104, Vol.79, No.3, p.#036104, 2009.03, Using a cellular automaton traffic model based on the stochastic optimal velocity model with appropriate assumptions for both incoming and outgoing vehicle boundaries, the so-called bottleneck issue on a lane-closing section was investigated in terms of game theory. In the system, two classified driver agents coexist: C agents (cooperative strategy) always driving in the first lane and D agents (defective strategy) trying to drive in a lower-density lane whether the first or the second lane. In high-density flow, D agents' interruption into the first lane from the second just before the lane-closing section creates a heavier traffic jam, which reduces social efficiency. This particular event can be described with a prisoner's dilemma game structure..
38. Atsuo Yamauchi, Jun Tanimoto, Aya Hagishima, Hiroki Sagara, Dilemma game structure observed in traffic flow at a 2-to-1 lane junction, PHYSICAL REVIEW E, 10.1103/PhysRevE.79.036104, Vol.79, No.3, p.#036104, 2009.03, Using a cellular automaton traffic model based on the stochastic optimal velocity model with appropriate assumptions for both incoming and outgoing vehicle boundaries, the so-called bottleneck issue on a lane-closing section was investigated in terms of game theory. In the system, two classified driver agents coexist: C agents (cooperative strategy) always driving in the first lane and D agents (defective strategy) trying to drive in a lower-density lane whether the first or the second lane. In high-density flow, D agents' interruption into the first lane from the second just before the lane-closing section creates a heavier traffic jam, which reduces social efficiency. This particular event can be described with a prisoner's dilemma game structure..
39. Aya Hagishima, Jun Tanimoto, Koji Nagayama, Sho Meno, Aerodynamic Parameters of Regular Arrays of Rectangular Blocks with Various Geometries, BOUNDARY-LAYER METEOROLOGY, 10.1007/s10546-009-9403-5, Vol.132, No.2, pp.315-337, 2009.08, The aerodynamic effects of various configurations of an urban array were investigated in a wind-tunnel experiment. Three aerodynamic parameters characterising arrays-the drag coefficient (C (d) ), roughness length (z (o)) and displacement height (d)-are used for analysis. C (d) is based on the direct measurement of the total surface shear using a floating element, and the other two parameters are estimated by logarithmic fitting of the measured wind profile and predetermined total drag force. The configurations of 63 arrays used for measurement were designed to estimate the effects of layout, wind direction and the height variability of the blocks on these parameters for various roughness packing densities. The results are summarised as follows: (1) The estimated C (d) and z (o) of the staggered arrays peak against the plan area index (lambda (p) ) and frontal area index (lambda (f) ), in contrast with values for the square arrays, which are less sensitive to lambda (p) and lambda (f) . In addition, the square arrays with a wind direction of 45A degrees have a considerably larger C (d) , and the wind direction increases z (o)/H by up to a factor of 2. (2) The effect of the non-uniformity of roughness height on z (o) is more remarkable when lambda (f) exceeds 20%, and the discrepancy in z (o) is particularly remarkable and exceeds 200%. (3) The effect of the layout of tall blocks on C (d) is stronger than that of short blocks. These results indicate that the effects of both wind direction and the non-uniformity of the heights of buildings on urban aerodynamic parameters vary greatly with lambda (p) and lambda (f) ; hence, these effects should be taken into account by considering the roughness packing density..
40. Aya Hagishima, Jun Tanimoto, Koji Nagayama, Sho Meno, Aerodynamic Parameters of Regular Arrays of Rectangular Blocks with Various Geometries, BOUNDARY-LAYER METEOROLOGY, 10.1007/s10546-009-9403-5, Vol.132, No.2, pp.315-337, 2009.08, The aerodynamic effects of various configurations of an urban array were investigated in a wind-tunnel experiment. Three aerodynamic parameters characterising arrays-the drag coefficient (C (d) ), roughness length (z (o)) and displacement height (d)-are used for analysis. C (d) is based on the direct measurement of the total surface shear using a floating element, and the other two parameters are estimated by logarithmic fitting of the measured wind profile and predetermined total drag force. The configurations of 63 arrays used for measurement were designed to estimate the effects of layout, wind direction and the height variability of the blocks on these parameters for various roughness packing densities. The results are summarised as follows: (1) The estimated C (d) and z (o) of the staggered arrays peak against the plan area index (lambda (p) ) and frontal area index (lambda (f) ), in contrast with values for the square arrays, which are less sensitive to lambda (p) and lambda (f) . In addition, the square arrays with a wind direction of 45A degrees have a considerably larger C (d) , and the wind direction increases z (o)/H by up to a factor of 2. (2) The effect of the non-uniformity of roughness height on z (o) is more remarkable when lambda (f) exceeds 20%, and the discrepancy in z (o) is particularly remarkable and exceeds 200%. (3) The effect of the layout of tall blocks on C (d) is stronger than that of short blocks. These results indicate that the effects of both wind direction and the non-uniformity of the heights of buildings on urban aerodynamic parameters vary greatly with lambda (p) and lambda (f) ; hence, these effects should be taken into account by considering the roughness packing density..
41. Jun Tanimoto, A simple scaling of the effectiveness of supporting mutual cooperation in donor-recipient games by various reciprocity mechanisms, BIOSYSTEMS, 10.1016/j.biosystems.2008.11.004, Vol.96, No.1, pp.29-34, 2009.04, In donor-recipient games (DRG), one of the sub-classes of Prisoner's Dilemma (PD), it is well-known that a game structure is described by two parameters benefit (b) and cost (c) of cooperation. By means of a series of numerical experiments, we proved that the effectiveness of supporting mutual cooperation in DRG by various reciprocity mechanisms can be expressed in a single game structural parameter, b/c. This also implies that the dilemma strength in various donor-recipient games with various reciprocity mechanisms can be evaluated only by b/c, which is consistent with the previous novel finding by Nowak. It was also discussed whether this kind of parameterization idea can be extended to general games in PD game class. (C) 2008 Published by Elsevier Ireland Ltd..
42. Ryo Matsuzawa, Jun Tanimoto, Eriko Fukuda, Properties of a new small-world network with spatially biased random shortcuts, PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS, 10.1016/j.physa.2017.05.031, Vol.486, pp.408-415, 2017.11, This paper introduces a small-world (SW) network with a power-law distance distribution that differs from conventional models in that it uses completely random shortcuts. By incorporating spatial constraints, we analyze the divergence of the proposed model from conventional models in terms of fundamental network properties such as clustering coefficient, average path length, and degree distribution. We find that when the spatial constraint more strongly prohibits a long shortcut, the clustering coefficient is improved and the average path length increases. We also analyze the spatial prisoner's dilemma (SPD) games played on our new SW network in order to understand its dynamical characteristics. Depending on the basis graph, i.e., whether it is a one-dimensional ring or a two-dimensional lattice, and the parameter controlling the prohibition of long-distance shortcuts, the emergent results can vastly differ. (C) 2017 Elsevier B.V. All rights reserved..
43. N. Ikegaya, Y. Ikeda, A. Hagishima, J. Tanimoto, Evaluation of rare velocity at a pedestrian level due to turbulence in a neutrally stable shear flow over simplified urban arrays, JOURNAL OF WIND ENGINEERING AND INDUSTRIAL AERODYNAMICS, 10.1016/j.jweia.2017.10.002, Vol.171, pp.137-147, 2017.12, The geometric dependency of the wind environment at a pedestrian level is an important issue that influences human comfort and safety in urban outdoor spaces. As such, this paper proposes to investigate the statistical features of wind speeds at the pedestrian level by calculating wind speed probability density functions based on flow field data from large-eddy simulations of simplified urban arrays, aiming to clarify the effects of urban geometry on rare velocity events such as strong gusts or extremely weak air flow. Though strong wind events occur infrequently, a positive correlation was demonstrated between percentile and mean wind speeds, indicating that the risk of gusty events increases with the increase of mean wind speeds. Conversely, the frequency of weak wind events shows an inverse correlation with mean wind speeds, showing that better ventilated urban arrays will retain higher wind speeds. Furthermore, these percentiles and occurrence frequencies are clearly expressed by the frontal area indices of urban block arrays. These results imply a trade-off between the following two objectives for urban area wind environments characterized by the urban geometry: enhancing air ventilation in urban areas and preventing strong wind gust events at a pedestrian level..
44. Jun Tanimoto, Does information of how good or bad your neighbors are enhance cooperation in spatial Prisoner's games?, CHAOS SOLITONS & FRACTALS, 10.1016/j.chaos.2017.05.038, Vol.103, pp.184-193, 2017.10, Network reciprocity is one of the key mechanisms to solve social dilemmas, and has attracted many researchers for the last decade. Here, we explore what happens if network reciprocity is dovetailed with indirect reciprocity. This is motivated by the idea that a player may utilize observed information to evaluate his neighbors. Simulations based on our minimal model reveal that adding indirect reciprocity does not always increase the level of cooperation beyond the level of model without indirect reciprocity. This implies that the combination of two different reciprocity mechanisms, each enhancing cooperation if applied independently, can lead negative interference effect on cooperation. The details of this depend on type of action assessment system determining what is good and bad. Interestingly, we found that a high level of information is not always superior to low levels of information. (C) 2017 Elsevier Ltd. All rights reserved..
45. Kazuki Kuga, Jun Tanimoto, Which is more effective for suppressing an infectious disease: Imperfect vaccination or defense against contagion?, Journal of Statistical Mechanics: Theory and Experiment, 10.1088/1742-5468/aaac3c, Vol.2018, No.2, 2018.02, We consider two imperfect ways to protect against an infectious disease such as influenza, namely vaccination giving only partial immunity and a defense against contagion such as wearing a mask. We build up a new analytic framework considering those two cases instead of perfect vaccination, conventionally assumed as a premise, with the assumption of an infinite and well-mixed population. Our framework also considers three different strategy-updating rules based on evolutionary game theory: conventional pairwise comparison with one randomly selected agent, another concept of pairwise comparison referring to a social average, and direct alternative selection not depending on the usual copying concept. We successfully obtain a phase diagram in which vaccination coverage at equilibrium can be compared when assuming the model of either imperfect vaccination or a defense against contagion. The obtained phase diagram reveals that a defense against contagion is marginally inferior to an imperfect vaccination as long as the same coefficient value is used. Highlights - We build a new analytical framework for a vaccination game combined with the susceptible-infected-recovered (SIR) model. - Our model can evaluate imperfect provisions such as vaccination giving only partial immunity and a defense against contagion. - We obtain a phase diagram with which to compare the quantitative effects of partial vaccination and a defense against contagion..
46. Various error settings bring different noise-driven effects on network reciprocity in spatial prisoner's dilemma
© 2018 Elsevier Ltd In view of stochastic resonance effect, this paper reports what type of additional noise can draw more enhanced network reciprocity in spatial prisoner's dilemma (SPD) games presuming different underlying networks as well as strategy updating rules. Relying on a series of simulations comprehensively designed, we explored various noise models namely action error, copy error, observation error, by either placing random agents or biased agents and variant settings of those. We found that the influence by adding noise significantly differs depending on the type of noise as well as the combination of what underlying network and update rule are presumed. Action error when added to SPD games presuming deterministic updating rule shows relatively large enhancement for cooperation..
47. Yoshiro Iwamura, Jun Tanimoto, Realistic decision-making processes in a vaccination game, Physica A: Statistical Mechanics and its Applications, 10.1016/j.physa.2017.11.148, Vol.494, pp.236-241, 2018.03, Previous studies of vaccination games have nearly always assumed a pairwise comparison between a focal and neighboring player for the strategy updating rule, which comes from numerous compiled studies on spatial versions of 2-player and 2-strategy (2 × 2) games such as the spatial prisoner's dilemma (SPD). We propose, in this study, new update rules because the human decision-making process of whether to commit to a vaccination is obviously influenced by a “sense of crisis” or “fear” urging him/her toward vaccination, otherwise they will likely be infected. The rule assumes that an agent evaluates whether getting a vaccination or trying to free ride should be attempted based on observations of whether neighboring non-vaccinators were able to successfully free ride during the previous time-step. Compared to the conventional updating rule (standard pairwise comparison assuming a Fermi function), the new rules generally realize higher vaccination coverage and smaller final epidemic sizes. One rule in particular shows very good performance with significantly smaller epidemic sizes despite comparable levels of vaccination coverage. This is because the specific update rule helps vaccinators spread widely in the domain, which effectively hampers the spread of epidemics..
48. Yuki Ida, Jun Tanimoto, Effect of noise-perturbing intermediate defense measures in voluntary vaccination games, Chaos, Solitons and Fractals, 10.1016/j.chaos.2017.11.031, Vol.106, pp.337-341, 2018.01, Recently, a new vaccination game model was proposed, where an intermediate defense measure besides two fundamental strategies
committing vaccination that leads to a perfect immunity and not committing vaccination, was introduced as third strategy. We explore what happens if both effectiveness and cost of an intermediate defense measure stochastically perturbing on the viewpoint of whether or not the third strategy helping to improve total social payoff. We found that unlike resonance effect by adding noise to payoff matrix in case of spatial prisoner's dilemma (SPD) games, adding time-varying noise on both effectiveness and cost does not make difference from the default setting without perturbation to the third strategy. However, if the noise initially given to each agent is frozen, we found the third strategy becoming robust to survive. In particular, if the strategy updating rule allows a more advantageous third strategy can be more commonly shared among agents through copying, the total social payoff is significantly improved..
49. Yoshiro Iwamura, Jun Tanimoto, Complex traffic flow that allows as well as hampers lane-changing intrinsically contains social-dilemma structures, Journal of Statistical Mechanics: Theory and Experiment, 10.1088/1742-5468/aaa8ff, Vol.2018, No.2, 2018.02, To investigate an interesting question as to whether or not social dilemma structures can be found in a realistic traffic flow reproduced by a model, we built a new microscopic model in which an intentional driver may try lane-changing to go in front of other vehicles and may hamper others' lane-changes. Our model consists of twofold parts
cellular automaton emulating a real traffic flow and evolutionary game theory to implement a driver's decision making-process. Numerical results reveal that a social dilemma like the multi-player chicken game or prisoner's dilemma game emerges depending on the traffic phase. This finding implies that a social dilemma, which has been investigated by applied mathematics so far, hides behind a traffic flow, which has been explored by fluid dynamics. Highlight - Complex system of traffic flow with consideration of driver's decision making process is concerned. - A new model dovetailing cellular automaton with game theory is established. - Statistical result from numerical simulations reveals a social dilemma structure underlying traffic flow. - The social dilemma is triggered by a driver's egocentric actions of lane-changing and hampering other's lane-change..