Laurent Philippe

University of Franche-Comté | UFC · UFR des Sciences et Techniques

Datacenters are an essential part of the internet, but their continuous development requires finding sustainable solutions to limit their impact on climate change. The Datazero2 project aims to design datacenters running solely on local renewable energy. In this paper, we tackle the problem of computing the minimum power demand to process a workloa...

Parmi les méthodes de modélisation/simulation, les systèmes multi-agents présentent un intérêt particulier pour simuler les systèmes complexes. Lorsque la taille des modèles croît, le recours à la simulation distribuée est nécessaire mais pose de nombreux problèmes. Dans cet article, nous nous intéressons à l’impact de la synchronisation sur l’impl...

Modern Multi-Agent System simulations may involve millions of agents that are simulated over an extended period of time in order to better catch real world emergent properties. In this context, the usage of distributed computing resources may raise single machine limits both in terms of available memory and execution time. Distributing a simulation...

As more and more activities are moving online, the need for datacenters is increasing which raises their energy consumption and the resulting greenhouse gas emissions. The supply of datacenters with renewable energy is often seen as the main solution to this nexus. However, multiple challenges are posed by their integration. Solutions to these chal...

Managing risks related to the actions and conditions of the various elements that make up an operating room is a major concern during surgery. Determining alert thresholds is one of the main challenges. In this document, we propose to focus on the causes that lead to incidents as well as their prediction, which are essential elements in the determi...

The energy consumption of large Information and Communications Technology structures such as data and computation centers along with the corresponding carbon footprint are on the rise. Green computing has become an indispensable solution to face the resulting economical and environmental challenges. Powering these centers with renewable energy sour...

Multi-Agent Systems (MAS) are naturally good candidates for large-scale parallel simulations. However, implementing MAS simulations for distributed memory architectures, such as High Performance Computing clusters, is still complex for non-experts. In this article we present the principle of a Dynamic Distributed Graph structure, that enables the n...

Managing the risks arising from the actions and conditions of the various ele- ments that make up an operating room is a major concern during a surgical procedure. One of the main challenges is to define alert thresholds in a non- deterministic context where unpredictable adverse events occur. In response to this problematic, this paper presents an...

Parmi les méthodes de modélisation/simulation, les sys-tèmes multi-agents présentent un intérêt particulier pour simuler les systèmes complexes. Lorsque la taille des mo-dèles croît, le recours aux systèmes multi-agents parallèles est nécessaire mais pose de nombreux problèmes. Dans cet article, nous nous intéressons à l'impact de la synchronisa-ti...

Risk management resulting from the actions and states of the different elements making up a operating room is a major concern during a surgical procedure. Agent-based simulation shows an interest through its interaction concepts, interactivity and autonomy of different simulator entities. We want in our study to implement a generator of alerts to l...

Data publishing is a challenging task for privacy preservation constraints. To ensure privacy, many anonymization techniques have been proposed. They differ in terms of the mathematical properties they verify and in terms of the functional objectives expected. Disassociation is one of the techniques that aim at anonymizing of set-valued datasets (e...

Disassociation is a bucketization based anonymization technique that divides a set-valued dataset into several clusters to hide the link between individuals and their complete set of items. It increases the utility of the anonymized dataset, but on the other side, it raises many privacy concerns, one in particular, is when the items are tightly cou...

As the need for cloud services has been growing steadily, the size and energy consumption of datacenters have increased significantly over the past years. Due to economic and environmental constraints, energy efficiency in datacenters and greenhouse emissions have become a major concern. Renewable energy is widely seen as a promising solution to su...

Data publishing is a challenging task from the privacy point of view. Different anonymization techniques are proposed in the literature to preserve privacy in accordance with some mathematical constraints. Disassociation is one of the anonymization techniques that relies on the km - anonymity privacy constraint to guarantee a certain level of priva...

Disassociation introduced by Terrovitis et al. is a bucketization based anonimyzation technique that divides a set-valued dataset into several clusters to hide the link between individuals and their complete set of items. It increases the utility of the anonymized dataset, but on the other side, it raises many privacy concerns, one in particular, i...

Computational simulation is becoming increasingly important in numerous research fields. Depending on the modeled system, several methods such as differential equations or Monte-Carlo simulations may be used to represent the system behavior. The amount of computation and memory needed to run a simulation depends on its size and precision, and large...

The number of complete chloroplastic genomes increases day after day, making it possible to rethink plants phylogeny at the biomolecular era. Given a set of close plants sharing in the order of one hundred of core chloroplastic genes, this article focuses on how to extract the largest subset of sequences in order to obtain the most supported specie...

Bias in the performance evaluation of scheduling heuristics has been shown to undermine the scope of existing studies. Improving the assessment step leads to stronger scientific claims when validating new optimization strategies. This article considers the problem of allocating independent tasks to unrelated machines such as to minimize the maximum...

Nowadays, we are more and more surrounded by powerful and intelligent communicating objects. Many of these objects, as smart- phones, watches, detectors and soon cars, are moving in increasingly interconnected environments, have abilities to communicate with each other and to exchange information. A collaborative approach allows these entities to e...

Assessing the performance of scheduling heuristics through simulation requires one to generate synthetic instances of tasks and machines with well-identified properties. Carefully controlling these properties is mandatory to avoid any bias. We consider the scheduling problem consisting of allocating independent sequential tasks on unrelated machine...

Simulation has become an indispensable tool for researchers to explore systems without having recourse to real experiments. Depending on the characteristics of the modeled system, methods used to represent the system may vary. Multi-agent systems are often used to model and simulate complex systems. In any cases, increasing the size and the precisi...

The amount of completely sequenced chloroplast genomes increases rapidly every day, leading to the possibility to build large-scale phylogenetic trees of plant species. Considering a subset of close plant species defined according to their chloroplasts, the phylogenetic tree that can be inferred by their core genes is not necessarily well supported...

This paper considers the problem of allocating independent tasks to unrelated machines such as to minimize the maximum completion time. Testing heuristics for this problem requires the generation of cost matrices that specify the execution time of each task on each machine. Numerous studies showed that the task and machine heterogeneities belong to...

Simulation has become an indispensable tool for researchers to explore systems without having recourse to real experiments. Depending on the characteristics of the modelled system, methods used to represent the system may vary. Multi-agent systems are thus often used to model and simulate complex systems. In any cases, increasing the size and the p...

Simulation has become an indispensable tool for researchers to explore systems without having recourse to real experiments. In this context multi-agent systems are often used to model and simulate complex systems. Depending on the characteristics of the modelled system, methods used to represent the system may vary. Whatever the modelling technique...

Code and data sets used in the research report ”Controlling and Assessing Correlations of Cost Matrices in Heterogeneous Scheduling”

The number of complete chloroplastic genomes increases day after day, making it possible to rethink plants phylogeny at the biomolecular era. Given a set of close plants sharing in the order of one hundred of core chloroplastic genes, this article focuses on how to extract the largest subset of sequences in order to obtain the most supported specie...

The interest for Multi-Agents Systems (MAS) grows rapidly and especially in order to simulate and observe large and complex systems. Centralized machines do not however offer enough capacity to simulate the large models and parallel clusters can overcome these limits. Nevertheless, the use of parallel clusters implies constraints such as mono-threa...

Assessing the performance of scheduling heuristics through simulation requires to generate synthetic instances of tasks and machines with well-identified properties. Carefully controlling these properties is mandatory to avoid any bias. We consider the scheduling problem consisting of allocating independent sequential tasks on unrelated processors...

Multi-agent models and simulations are used to describe complex systems in domains such as biological, geographical or ecological sciences. The increasing model complexity results in a growing need for computing resources and motivates the use of new architectures such as multi-cores and many-cores. Using them efficiently however remains a challeng...

Self-avoiding walks (SAWs) are the source of very difficult problems in probability and enumerative combinatorics. They are of great interest as, for example, they are the basis of protein structure prediction (PSP) in bioinformatics. The authors of this paper have previously shown that, depending on the prediction algorithm, the sets of obtained w...

Simulation has become an indispensable tool for researchers to ex-plore systems without having recourse to real experiments. Depending on the characteristics of the modeled system, methods used to repre-sent the system may vary. Multi-agent systems are, thus, often used to model and simulate complex systems. Whatever modeling type used, increasing...

In this paper, we tackle the well-known problem of scheduling a collection of parallel jobs on a set of processors either in a cluster or in a multiprocessor computer. For the makespan objective, that is, the completion time of the last job, this problem has been shown to be NP-hard, and several heuristics have already been proposed to minimize the...

In this article we study both the throughput and the energy optimization problem for a distributed system subject to failures that executes a workflow at different speed levels. The application is modeled as a directed acyclic graph composed of typed tasks linked by dependency constraints. A continuous flow, or a great number of application instanc...

Multi-agent models and simulations are used to describe complex systems in domains such as biological, geographical or ecological sciences. The increasing model complexity results in a growing need for computing resources and motivates the use of new architectures such as multi-cores and many-cores. Using them efficiently however remains a challeng...

Evolutionary algorithms (EA) are recently used to explore the parameter space of complex system simulations as the methodology sees models as black boxes. The first advantage is that these algorithms become independent from what kind of simulation has to be explored. The task is finding the parameter settings to optimize a given objective function....

Multi-agent models and simulations are used to describe complex systems in domains such as biological, geographical or ecological sciences. The increasing model complexity results in a growing need for computing resources and motivates the use of new architectures such as multi-cores and many-cores. Using them efficiently however remains a challeng...

In this paper, we study the problem of optimizing the throughput of streaming applications for heterogeneous platforms subject to failures. Applications are linear graphs of tasks (pipelines), with a type associated to each task. The challenge is to map each task onto one machine of a target platform, each machine having to be specialized to proces...

Various subsets of self-avoiding walks naturally appear when investigating existing methods designed to predict the 3D conformation of a protein of interest. Two such subsets, namely the folded and the unfoldable self-avoiding walks, are studied computationally in this article. We show that these two sets are equal and correspond to the whole $n$-s...

Self-avoiding walks (SAW) are the source of very difficult problems in probabilities and enumerative combinatorics. They are also of great interest as they are, for instance, the basis of protein structure prediction in bioinformatics. Authors of this article have previously shown that, depending on the prediction algorithm, the sets of obtained co...

Multi-Agent Systems (MAS) can be used to model systems where the global behavior cannot be uniformly represented by standard techniques such as partial differential equations or linear systems because the system elements have their own independent behavior. This is, for instance, the case in complex systems such as daily mobility in a city for exam...

In this chapter we introduce the use of Graphical Processing Units (GPU) for multi-agents-based systems as an example of a not-so-regular application that could benefit from the GPU computing power. Multi-Agent Systems (MAS) are a simulation paradigm used to study the behavior of dynamic systems. Dynamic systems as physical systems are often modele...

In this paper we tackle the well-known problem of scheduling a collection of parallel jobs on a set of processors either in a cluster or in a multiprocessor computer. For the makespan objective, i.e., the completion time of the last job, this problem has been shown to be NP-Hard and several heuristics have already been proposed to minimize the exec...

In this paper we consider microfactories for manipulation and assembly. These microfactories are composed of several cells containing microrobotic systems capable of a high level of repeatability. The assembly plan of the production is a pipeline of tasks that are performed by the cells. Our aim is to manage the production flow in the case where th...

Multi-Agent System (MAS) is an interesting way to create models and simulators and is widely used to model complex systems. As the complex system community tends to build up larger models to fully represent real systems, the need for computing power raise significantly. Thus MAS often lead to long computing intensive simulations. Parallelizing such...

In this paper, we consider the makespan optimisation when scheduling a batch of identical workflows on a heterogeneous platform as a service-oriented grid or a micro-factory. A job is represented by a directed acyclic graph (DAG) with typed tasks and no fork nodes (in-tree precedence constraints). The processing resources are able to process a set...

In this paper, we tackle pipeline workflow applications that are executed on a dis- tributed heterogeneous platform with setup times. In such applications, several computation stages are interconnected as a linear application graph. The considered stage/processor mapping strategy is based on interval mappings, where an interval of consecutive stage...

Complex processes, as geographical mobilities, cannot be always modeled by mathematical formulas or probability laws due to the number of parameters that characterize their behavior. For this reason, simulation is generally used to study movements in these systems. Multi-Agent Systems (MAS) are an interesting and intuitive way to model such complex...

In this paper, we focus on the problem of scheduling a collection of similar task graphs on a heterogeneous platform, when the task graph is an intree. We rely on steady-state scheduling techniques, and aim at optimizing the throughput of the system. Contrarily to previous studies, we concentrate on practical aspects of steady-state scheduling, whe...

In this paper we study the problem of scheduling a collection of workflows, identical or not, on a SOA (Service Oriented Architecture) grid . A workflow (job) is represented by a directed acyclic graph (DAG) with typed tasks. All of the grid hosts are able to process a set of typed tasks with unrelated processing costs and are able to transmit file...

In this report, we study the problem of optimizing the throughput of applications for heterogeneous platforms subject to failures. The considered applications are composed of a sequence of consecutive tasks linked as a linear graph (pipeline), with a type associated to each task. The challenge is to specialize the machines of a target platform to p...

We study the problem of optimizing the throughput of coarse-grain workflow applications, for which each task of the workflow is of a given type, and subject to failures. The goal is to map such an application onto a heterogeneous specialized platform, which consists of a set of processors that can be specialized to process one type of tasks. The ob...

In this paper we study the problem of batch scheduling within a homogeneous cluster. In this context, the problem is that the more processors the job requires the more difficult it is to find an idle slot to run it on. As a consequence the resources are often inefficiently used as some of them remain unallocated in the final schedule. To address th...

This paper presents the work done during the first year of the EPIS project. This project deals with the process of conductingmultiple and parallelmulti agents-based simulations (MABS) on a cluster or a grid in order to generate sufficient data for scientific use (e.g. in the case of a sensibility analysis of a simulation). We provide a new, genera...

This paper presents the work done during the first year of the EPIS project. This project deals with the process of conducting multiple and parallel multi agents-based simulations (MABS) on a cluster or a grid in order to generate sufficient data for scientific use (e.g. in the case of a sensibility analysis of a simulation). We provide a new, gene...

In this paper, we study the problem of optimizing the throughput for micro-factories subject to failures. The challenge consists in mapping several tasks of different types onto a set of machines. The originality of our approach is the failure model for such applications in which not only the machines are subject to failures but the reliability of...

Search algorithms are a key issue to share resources in large distributed systems as peer networks. Several distributed interconnection structures and algorithms have already been studied in this context. With expanding ring algorithms, the efficiency of searches depends on the topology used to send query requests and on the dynamics of the structu...

In this paper, we focus on the problem of scheduling batches of identical task graphs on a heterogeneous platform, when the task graph consists in a tree. We rely on steady-state scheduling, and aim at reaching the optimal throughput of the system. Contrarily to previous studies, we concentrate upon the scheduling of batches of limited size. We try...

In this paper, we study the problem of optimizing the throughput for micro-factories subject to failures. The challenge consists in mapping several tasks onto a set of machines. The originality of our approach is the failure model for such applications in which tasks are subject to failures rather than machines. If there is exactly one task per mac...

Distributed platforms become heterogeneous in more and more domains, as heterogeneous computing (HC) onto grids or reconfigurable factories in the industry. For production grids and factories, it is mandatory to control and optimize the economic cost of a such platforms regarding performance objectives. We present in this paper a study which purpos...

In this paper we consider the scheduling of a batch of workflows on a service oriented grid. A job is represented by a directed acyclic graph without forks (intree) but with typed tasks. The processors are distributed and each processor have a set of services that carry out equivalent task types. The objective function is to minimize the makespan o...

Random graph and tree are two topologies used to build overlay networks. These overlay networks may be used by large scale discovery mechanisms to run search algorithms. The distributed spanning tree (DST) is another topology that may be used as overlay. In a DST, every computer is a leaf. DST's non-leaf nodes are sets of computers instead of compu...