Crowd Characteristics Research Articles

Modeling and Simulation of Explosion Effectiveness as a Function of Blast and Crowd Characteristics

Explosions in civil settings are becoming the daily news. While various explosive simulations and models have been developed for battlefield and industrial settings, much less has been done for civil settings and urban terrains.This paper presents the science of suicide bombing and explains the physics, explosive models, mathematics, and the assumptions we need to create such a simulation.The proposed simulation tool is capable of assessing the impact of crowd formation patterns and their densities on the magnitude of injury and number of casualties during a suicide bombing attack. Results indicate that the worst crowd formation is a street (zigzag) where 30% of the crowd can be dead and 45% can be injured, given the typical explosive carrying capacity of a single suicide bomber. Row-wise crowd formation was found to be the best for reducing the effectiveness of an attack with 18% of the crowd in the lethal zone and 38% in the injury zone. Crowd blockage and densities can reduce the fatalities by 12% and injuries by 7%. Simulation results were compared and validated by real-life incidents and found to be in good agreement. These findings, although preliminary, may have implications for emergency response and counter terrorism.

REPRESENTATION OF CROWD IN MULTI-AGENT MODEL

SimTread has been developed as a pedestrian simulation system with straightforward pedestrian and space model, which is highly operable by the users. The pedestrian model is a multi agent system in which the individual pedestrian is modeled as agents, and the space model is based on real coordinates, on the contrary of network and mesh models, that enable to represent plans directly into models.The characteristics of crowd represented in this system had been evaluated through test cases by measuring the flow rate that is a major index for evaluating crowd.Major results are as follows 1. In a simple plan that are comparable to network models, SimTread showed reasonable behaviours of crowds, which in terms of operability, can be concluded as highly desirable performance. 2. In a case where a bottleneck accumulates enough pedestrians so that consecutive exits will be virtually closed, SimTread showed accurately the propagation of crowd, which led to qualitative analysis of the crowd.

Characteristics of current crowding in flip-chip solder bumps

For a flip-chip package assembly, current crowding occurs in the vicinity of the locations where traces connect the solder bumps. This feature contributes significantly to the electromigration failure of the solder bumps. In this study the finite element analysis is performed to investigate characteristics of current crowding in a flip-chip solder bump subjected to a constant applied current. It is found that under such a condition, current crowding is induced solely by the structural geometry of the system. It is independent of the magnitude of the applied current. A volumetric averaging technique is also applied to cope with the current crowding singularity.

Epidemic theory and group violence

Epidemics can be represented mathematically using a variety of models. One of these, the Kermack-McKendrick model, has been used to support health policy decisions concerning vaccination requirements. An unrelated body of literature suggests that some behaviours, including some types of violence, may spread in ways analogous to the contagious spread of infectious diseases, a process that has been characterized as "behavioural contagion". Various parameter values reflecting the characteristics of crowds were substituted into the Kermack-McKendrick model. Computer simulations were used to evaluate the impact of these parameter values. The simulations reproduced several features of crowd violence: the tendency for riots to occur in large groups, the importance of rapid removal of violent individuals from crowds, and the roles of alcohol consumption and social identification processes. Epidemic models may be of relevance to the prevention and control of violent behaviour as they can assist with the identification of high-risk situations and prevention strategies. Theoretical constructs related to epidemic theory may have broad applicability for modelling the unstable course of some mental disorders.

Hedonic Independence and Taste-Homogeneity of Organizations with Crowding Types

We consider a model of a local public goods economy with differentiated crowding that distinguishes between the tastes and crowding characteristics of agents. Crowding characteristics are those aspects of an agent that have a direct external effect on other members of the coalition to which he belongs. In such an economy, it is possible to form completely taste-homogeneous organizations while still taking advantage of the full array of possible crowding effects (labor complementarities, for example). We find, however, that it is nevertheless possible for taste-heterogeneous organizations to be strictly superior to taste-homogeneous organization with the same distribution of crowding types. We introduce a notion of hedonic independence, which stipulates that the values of an agent's characteristics (his taste type and his crowding type) are independent. We show that if hedonic independence is satisfied, then organizations in core and equilibrium states of the economy are essentially taste-homogeneous. A number of examples illustrate the application of our approach to several sorts of organizations. We conclude by discussing how hedonic independence might arise from market interactions.

Tiebout Economies with Differential Genetic Types and Endogenously Chosen Crowding Characteristics

We consider a Tiebout economy with differential crowding and public projects in which agents are distinguished by their tastes and genetic endowments. Agents choose which crowding characteristic, for example, a skill, they wish to express, and this affects their value to other members of their jurisdiction, club, firm, etc. An agent's choice is influenced both by his genetic endowment, which affects his cost of acquiring crowding characteristics, and by his preferences over which crowding characteristic he expresses. We show that if small groups are strictly effective, the core is equivalent to the set of anonymous competitive equilibrium outcomes, but that the core generally contains taste-homogeneous jurisdictions. Journal of Economic Literature Classification Numbers: H41, H72.

画像処理による群集の特徴評価に関する研究

In this report, I describe the method for analyzing crowd characteristics by image processing, using a CCD camera and image processor controlled by micro computer. I calculated the accumulation of the difference between background and input image. From this accumulation. I was able to automatically get information about the crowd, such as the number of pedestrians, and about the space which is used for walking or standing. I confirmed the efficiency of this method by experiment in buildings.

Neutron Radiation Damage in Silicon Transistors

In the investigation of base and collector current as a function of the emitter-to-base voltage, previous studies have shown that neutroninduced base current has components originating in the emitter space charge region as well as the neutral base region. This study shows that while the low injection level neutron-induced base current is dominated by the space charge component, the high injection behavior appears to be controlled by recombination in the neutral base region. Additional experiments performed in special tetrode transistors and van der Pauw-type samples indicate that changes in collector current are dominated by recombination in the neutral base, while changes in base doping and mobility have only a secondary effect. These conclusions are reached from experiments on transistors with a ring emitter, on tetrode-type test transistors, and on special Hall-effect devices, and by a detailed analysis of the emission crowding characteristics of a "ring-dot" geometry device.