An autonomous and guided crowd in panic situations

This paper describes a model for simulating crowds in real time. We deal with the hierarchy of the crowd, groups and individuals. The groups are the most complex structure that can be controlled in different degrees of autonomy. The autonomy means that the virtual agents are independent of the user intervention. Depending on the complexity of the simulation, some simple behaviors can be sufficient to simulate crowds. Otherwise, more complicated behaviors rules can be necessary in order to improve the realism of the animation. We present two different ways for controlling crowd behaviors: - by defining behavior rules, to give intelligence to the agent. By providing an external control to guide crowd behaviors, this control is done by the user or by an autonomous agent called the guide. The main contribution of our approach is to combine these two ways of behaviors (autonomous, guide) in order to simulate the evacuation of a crowd in emergency situations. Many strategies of evacuation have been implemented and we will demonstrate that in most situations, the guided method decrease the average escape time and increase the chance of survival in emergency situations.Facultad de Informátic

AGENT-BASED MODEL FOR MICROSIMULATION OF LARGE SCAL PEDESTRIAN CROWD

In this paper, we addresses the development of agent-based model for real-time simulation of large scale pedestrian crowds.Its focus is to produce realistic pedestrian navigation and path planning within the environment whilst maintaining real time frame rates.The main assumption of this work is that the navigational behaviors of pedestrians are modeled realistically through hierarchical motions in multi layers of path planning, local path determination and locomotion. The inter-relationship between these layers is defined.Our method can be easily combined with most current local collision-avoidance methods and we use two such methods as examples to highlight the potential of our approach. .We also demonstrate some simulation results of Guarder to show that it could efficiently simulate life like crowd behaviors in a large-scale and complex environment

Path Finding and Collision Avoidance in Crowd Simulation

Motion planning for multiple entities or a crowd is a challenging problem in today’s virtual environments. We describe in this paper a system designed to simulate pedestrian behaviour in crowds in real time, concentrating particularity on collision avoidance. On-line planning is also referred as the navigation problem. Additional difficulties in approaching navigation problem are that some environments are dynamic. In our model we adopted a popular methodology in computer games, namely A* algorithm. The idea behind A* is to look for the shortest possible routes to the destination not through exploring exhaustively all the possible combination but utilizing all the possible directions at any given point. The environment is formed in regions and the algorithm is used to find a path only in visual region. In order to deal with collision avoidance, priority rules are given to some entities as well as some social behaviour

STRUCTURAL VALIDATION OF SOFTWARE PRODUCT LINE VARIANTS: A GRAPH TRANSFORMATIONS BASED APPROACH

ABSTRAC

A new cineol derivative, polyphenols and norterpenoids from Saharan myrtle tea (Myrtus nivellei): Isolation, structure determination, quantitative determination and antioxidant activity

Abstract The phytochemical profile of decoction and infusion, obtained from the dried leaves of M. nivellei, consumed as tea in Saharan region, was characterized by UHPLC-PDA-HRMS. Fourteen compounds were characterized and, to confirm the proposed structures a preparative procedure followed by NMR spectroscopy was applied. Compound 3 (2-hydroxy-1,8-cineole disaccharide) was a never reported whereas a bycyclic monoterpenoid glucoside (2), two ionol glucosides (1 and 12), a tri-galloylquinic acid (4), two flavonol glycosides (5 and 9), and a tetra-galloylglucose (7), were reported in Myrtus spp. for the first time. Five flavonol O-glycosides (6, 8, 10–11, and 14) togheter a flavonol (13) were also identified. Quantitative determination of phenolic constituents from decoction and infusion has been performed by HPLC-UV-PDA. The phenolic content was found to be 150.5 and 102.6 mg/g in decoction and infusion corresponding to 73.8 and 23.6 mg/100 mL of a single tea cup, respectively. Myricetin 3-O-β-d-(6″-galloyl)glucopyranoside (5), isomyricitrin (6) and myricitrin (8) were the compounds present in the highest concentration. The free-radical scavenging activities of teas and isolated compounds was measured by the DPPH assay and compared with the values of other commonly used herbal teas (green and black teas). Decoction displayed higher potency in scavenging free-radicals than the infusion and green and black teas

A Practical Approach to the Measurement of Similarity between WSDL-based Web Services

International audienceSimilarity measurement between web services is a key solution to benefit from the reuse of the large number of web services freely available in the internet. This paper presents a practical approach that enables an effective measurement of web service similarity based on their interfaces descibed with WSDL. The approach relies on the use of multiple matching techniques and different semantic and structural similarity metrics. The measurement of similarity determines the best substitute for a failed web service. So, it serves as a good indicator of the substitutability relation and thus of the capacity for reuse. A support tool, implementing the approach, is also presented with some experimental results conducted on real-world web services

Processing the Evolution of Quality Requirements of Web Service Orchestrations: A Pattern-Based Approach

International audienceCurrently Web services remain one of the leading technologies for implementing components of service-oriented software architectures. One of the most frequent form of composi-tions of these entities is Web service orchestration. As any other software artifact, such service compositions are subject to an unescapable evolution (Lehman's first law of software evolution). Either for answering new user requirements, for adapting, for correcting or for enhancing the provided functionality or quality, an architect has to conduct some evolutions on the design of these artifacts. In this paper, we present a method which aims at helping software architects of Web service orchestrations in processing an evolution of quality requirements. This method introduces a template for describing quality evolution "intents". It then analyzes these intents and assists the architects in answering them by proposing some patterns. We consider in our work the postulate stating that quality can be implemented through patterns, which are specified with checkable/processable languages. Besides this, the method that we propose simulates the application of these patterns and notifies the architect with its consequences on the other implemented qualities

Quality-Driven Design of Web Service Business Processes

International audienceWeb service business processes are a kind of service compositions considered as one of the most frequent form of service-oriented software architectures. In this paper, we present a method that helps software architects in the design of such service architectures. This method assists the architects in answering them by proposing some patterns achieving quality requirements. We consider in our work that quality can be achieved through patterns, which are specified with checkable/process able languages. Besides this, the method that we propose simulates the application of these patterns and notifies the architect with its consequences on the other implemented qualities.Published in: 201

Evaluation de l'usage d'Internet par des élèves d'une école primaire

Arnaud Michel, Foudil Cherif Yassine, Sureau Mathilde. Evaluation de l'usage d'Internet par des élèves d'une école primaire . In: Sciences et techniques éducatives, volume 4 n°2, 1997. pp. 225-236