Ben Hadhami

Raoudha Slama
email: raoudha.gaha@gmail.com.

Abdelmajid Gaha

Benamara

Slama

Raoudha Gaha
email: raoudha.gaha@gmail.com

Abdelmajid Benamara

Proposal of a new based feature-interaction eco-manufacturing methodology on CAD phase

Keywords: CAD/ Eco-design/ Ecomanufacturing/ Environmental Impact/multicriteria decision support / Scenarios/ Feature interaction, 2, Eco-manufacturing: Overview

Following the many environmental crises of recent decades, a turning point in the awareness of the fragility of ecosystems has been marked, that is to say an environmental awareness. This has contributed to the development of various environmental laws and regulations such as the «Waste Electrical and Electronic Equipment" (WEEE), "Restriction of Hazardous Substances" (RoHS) and «Energy Using Products" (EuP) Directives or the "Registration, Evaluation, Authorization and Restriction of Chemicals" (REACH) Regulation.

Then, the productive model of industrial societies is questioned. A greater awareness of environmental issues is emerging. At the beginning and with the aim of minimizing the environmental impacts (EIs), the research work focused essentially on two axes: recycling and chemical substances. The process plan operations order has also an influence on the EIs of a product. In this paper, we propose a new based scenarios methodology by using the feature interactions technology (FIT) and a multi-criteria decision support method (MCDSM) that allows the non-environmental expert designer to have the optimal manufacturing process plan on CAD phase. First, we present our state of art. Then, we introduce our new methodology based on both FIT and MCDSM in order to choose the greenest manufacturing scenario. Finally, a case study of feature interaction will be presented for demonstration purposes.

Introduction

Following the many environmental crises of recent decades, a turning point in the awareness of the fragility of ecosystems has been marked, that is to say an environmental awareness. A wide range of environmental problems has emerged. Those problems include anthropogenic climate change (global warming), the acidification of surface water (acid rain), depletion of stratospheric ozone (ozone hole), etc. This has contributed to the development of various environmental laws and regulations such as the «Waste Electrical and Electronic Equipment" (WEEE)

[1], "Restriction of Hazardous Substances" (RoHS) [2] and «Energy Using Products" (EuP) [3] Directives or the "Registration, Evaluation, Authorization and Restriction of Chemicals" (REACH) [START_REF]Evaluation, Authorization and Restriction of Chemicals (REACH)[END_REF] Regulation. Thus, the productive model of industrial societies is questioned hence the birth of the concept of ecodesign. Eco-design approaches, aimed at reducing the environmental impacts of products over their entire life cycle, neglect the manufacturing phase. Manufacturing is the transformation of a raw material into a finished product by a process that causes a waste and environmental emissions. Therefore, researchers in this field tend to reduce environmental impacts from the manufacturing phase, where the notion of eco-manufacturing comes from. In this paper, first we present a literature review of works treating the optimization of the manufacturing phase from an environmental point of view. Second, we present a state of the art presenting eco-manufacturing integrating Computer Aided Design (CAD) systems; also, we underline the role of multicriteria decision support methods and the micro/macro-planning in the designer's decision-making regarding the greenest manufacturing scenario. Third, we describe our approach in order to eco-assist designers early in the design process and we validate it on a case study. Finally, we conclude our points and we propose perspectives for this work.

Manufacturing Optimization from an environmental point of view

Manufacturing operations consume energy. Overall, they account for 19% of greenhouse gas emissions [START_REF] Herzog | World greenhouse gas emissions: 2005[END_REF] and 37% of energy consumption [START_REF]World final consumption[END_REF]. With regard to energy consumption, a lot of methods for energy measurement; monitoring, modeling and optimization are applied to machining systems in order to improve their energy performance. For machining, the improvement of processes that surpass efficiency measures requires the measurement of the energy consumption of machining processes or systems [START_REF] Fresner | Energie-und Ressourceneffizienz in Unternehmenumsetzen[END_REF], [START_REF] Kara | Electricity metering and monitoring in manufacturing systems[END_REF].

Energy modeling and optimization are considered as basic measures for energy efficient machining. Energy models can be divided into three categories:

• Linear type cutting energy consumption models which are based on material removal rate (MRR), • Detailed parameter type cutting energy consumption correlation models • The process-oriented machining energy consumption model. In 2016, Feng et al formulated multicriteria optimization approaches for making the best use of energy delivered to the production processes [START_REF] Feng | Energy, economy, and environment analysis and optimizationon manufacturing plant energy supply system[END_REF]. In 2017, Hu et al introduced a single objective optimization problem minimizing the machine tools energy consumption (MTE) while machining a part [START_REF] Hu | Minimising the machining energy consumption of a machine tool by sequencing the features of a part[END_REF]. In 2017, He et al represented a method to optimize machining parameters with respect to the both environmental and economic objectives [START_REF] He | Pareto fronts of machining parameters for trade-off among energy consumption, cutting force and processing time[END_REF]. In 2018, another study is represented by Hu et al [START_REF] Hu | Minimising the energy consumption of tool change and tool path of machining by sequencing the features[END_REF] to clarify the relationship between the processing sequence of a part features (PSFP) and the energy consumption of tool change and tool path during the feature transitions. They introduce a model that minimizes the energy consumption of machine tools during the feature transitions which include all the tool path and tool change operations.

Carbon Dioxide CO2 is the most dangerous greenhouse gas in the atmosphere. Since the industrial revolution, the concentration of CO2 rises and reaches 410 ppm (parts per million, i.e.; number of moles CO2 per million moles of air) in June 2018 [13]. The CO2 emissions contribute to global warming caused by the rise in temperatures and climate change [START_REF] Gutowski | The carbon and energy intensity of manufacturing[END_REF][START_REF] Ipcc | Summary for policymakers[END_REF]. Then, with the growing concerns on ecosystems, several intergovernmental and blinding agreements are introduced to reduce the impacts of global warming. For instance, countries adopted the Paris Agreement at the COP21 in Paris, which went into force in November of 2016 [16]. Manufacturing has an essential role that radically influences our ecosystems; thus, many researches are focused on industrial activities aiming to reduce the carbon intensity. In 2016, Liu et al also presented a numerical approach to calculate optimal cutting parameters in the aim to reduce carbon emissions and machining costs [START_REF] Liu | Multi-objective optimization of the operating conditions in a cutting process based on low carbon emission costs[END_REF]. Zhang et al in 2017 proposed an optimization model for the process parameters of multi-pass dry machining to trade off process time, energy consumption and carbon emissions and then relieve the impact the environment [START_REF] Zhang | A process parameters optimization method of multi-pass dry milling for high efficiency, low energy and low carbon emissions[END_REF]. Liu et al propose an integrated optimization model based on cutting parameters and it affect scheduling in order to reduce the completion time and the carbon emissions in machining processes [START_REF] Liu | Integrated optimization of cutting parameters and scheduling for reducing carbon emissions[END_REF]. In 2018, Sihag and Sangwan presented a systematic methodology to calculate the carbon emissions of CNC machine tool [20].

The optimization of the manufacturing phase can be also seen in the minimization of cutting parameters regarding different environmental impacts. In 2017, Li et al presented an integrated approach of process planning and cutting parameter optimization to minimize the total energy consumption of CNC machining based on a multiobjective simulated annealing algorithm [START_REF] Li | An integrated approach of process planning and cuttingparameter optimization for energy-aware CNC machining[END_REF]. Rajesh et al also, study cutting parameters optimization in order to reduce cutting temperature in turning based on a Genetic Algorithm at dry and MQL condition [START_REF] Rajesh | optimization of cutting parameters for minimization of cutting temperature and surface roughness in turning of Al6061 alloy[END_REF]. Shin et al present a new methodology in order to implement an online energy optimization environment. This methodology is used s to select optimal cutting parameters [START_REF] Shin | Energy efficiency of milling machining: Component modeling and online optimization of cutting parameters[END_REF]. Figure 1 illustrates an overall flow of the proposed methodology. In 2018, Zhou et al presented a cutting parameter optimization method for machining operations to balance carbon emissions, cutting time and cutting cost, in the part machining process [START_REF] Zhou | Cutting parameter optimization for machining operations considering carbon emissions[END_REF]. One the unsustainable process is lubrication-based machining process due to the bad impact of cutting fluid on the environment. Hence, Alok and Das in 2019 present a multi-objective optimization of cutting parameters during sustainable dry hard turning [START_REF] Alok | Multi-objective optimization of cutting parameters during sustainable dry hard turning of AISI 52100 steel with newly develop HSN2-coated carbide insert[END_REF]. Chen et al. also proposes an integrated approach of cutting tool and cutting parameter optimization to minimize the energy footprint and production time of the face milling process using a multi-objective Cuckoo Search algorithm [START_REF] Chen | Integrated optimization of cutting tool and cutting parameters in face milling for minimizing energy footprint and production time[END_REF].

The use of cutting fluids in machining has a very hazardous effect. It leads to health and environmental problems. Therefore, the disposal of cutting fluids must be optimized in order to respect the environment protection laws. Vegetable-based ecofriendly cutting fluids are in demand. Several researches considered vegetable-based cutting fluids as an environmentally friendly fluids and it has a better lubricating ability comparing to other fluids [START_REF] Debnath | Environmental friendly cutting fluids and cooling techniques in machining: a review[END_REF][START_REF] Gajrani | Past and current status of eco-friendly vegetable oil based metal cutting fluids[END_REF]. Moreover, alternative ecofriendly machining techniques such as minimum quantity lubrication (MQL), cryogenic machining, etc. are required in order to reduce detrimental environmental effects of cutting fluids. Therefore, researchers are interested in dry machine technique. This technique uses coated tools [START_REF] Klocke | Coated tools for metal cutting-features and applications[END_REF] textured cutting tools [START_REF] Gajrani | State of the art on micro to nano textured cutting tools[END_REF][START_REF] Gajrani | Experimental comparative study of conventional, micro-textured and coated micro-textured tools during machining of hardened AISI 1040 alloy steel[END_REF], and other sustainable techniques [START_REF] Chetan | Application of sustainable techniques in metal cutting for enhanced machinability: A review[END_REF]. Near-dry machining or MQL or minimum quantity cutting fluid (MQCF) represent a solution so as to hazardous environmental effects [START_REF] Dixit | Environmentally Friendly Machining[END_REF][START_REF] Shaikh | Analyzing the effectiveness of microlubrication using a vegetable oil-based metal working fluid during end milling AISI 1018 steel[END_REF][START_REF] Sharma | Effects of minimum quantity lubrication (MQL) in machining processes using conventional and nanofluid based cutting fluids: A comprehensive review[END_REF][START_REF] Poyner | Integration of DFE tools with product development[END_REF][START_REF] Roche | The Development of a DFE Workbench[END_REF].

Fig 1. An overall flow of the proposed methodology by [23]

In this section, we observed from the above literature that multiple studies consider energy consumption, carbon emission and cutting fluids as an important process response. However, it is clear that in order to determine the optimal decision making, requires the knowledge of the different techniques that the designer is not an expert. Therefore, the eco-manufacturing integrating CAD is highlighted in the next section.

Eco-manufacturing integrating CAD

To increase productivity, companies are asking for improved CAD tools combining different functions such as manufacturing, cost estimation, environmental assessment, etc. Therefore, the trend in CAD systems is to integrate non-geometrical information at different levels into the purely geometrical model, such as taking into account engineering constraints and features. Bianconi et al distinguish two main areas of data exchange: horizontal (the same level of product development) and vertical (exchanging data between systems of different levels of product development) exchange [START_REF] Otto | A framework for structured data retrieval in LCA using feature technology[END_REF].

The need to analyze products in environmental terms during its design phase has led to the development of environmental impact analysis tools integrating CAD systems. Several studies, according to the literature, attempt to link these two types of software to help the designer make decisions. The history of integrating CAD systems with eco-design tools began in 1995. Among these works are methodologies [START_REF] Otto | Integration of CAD Models with LCA[END_REF][START_REF] Capelli | Integration of LCA and Eco-Design guideline in a virtual cad framework[END_REF][START_REF] Hagström | Integration of Environmental Assessment Functions in Design and Product Development Tools[END_REF][START_REF] Marosky | Challenges of data transfer between CAD and LCA software tools[END_REF][START_REF] Melk | A Generic Framework for Life Cycle Applications[END_REF][START_REF] Gaha | Influence of geometrical characteristics on ecodesigned products[END_REF][START_REF] Yang | A Green-Feature Based LCA Backtracking Mechanism[END_REF][START_REF] Russo | Structural optimization strategies to design green products[END_REF][START_REF] Hassine | Modélisation, simulation et optimisation pour l'´éco-fabrication[END_REF], prototype tools [START_REF] Takao | An Ecological Design Support Tool for Recyclability[END_REF][START_REF] Pahng | Distributed Modeling and Evaluation of Product Design Problems[END_REF][START_REF] Mathieux | CONNECTING CAD AND PLM SYSTEMS WITH ECODESIGN SOFTWARE: CURRENT EXPERIENCES AND FUTURE OPPORTUNITIES[END_REF][START_REF] Cappelli | Strumentoinformaticointegrato in ambiente cad per l'analisipreventivadegliimpattiambientalideiprocessi/ prodotti in fase di produzione[END_REF][START_REF] Abad | An ontology-based approach to integrating life cycle analysis and computer aided design[END_REF][START_REF] Jain | Design of an Interactive Eco-Assessment GUI tool for Computer Aided Product Design[END_REF][START_REF] Morbidoni | Environmental evaluation from cradle to grave with CAD-integrated LCA tools[END_REF][START_REF] Gaha | Eco-conception et CAO paramétrique[END_REF][START_REF] Chen | A feature-based CAD-LCA software integration approach for ecodesign[END_REF] or commercial tools [START_REF] Leibrecht | Fundamental Principles for CADbased Ecological Assessments[END_REF][START_REF] Solidworks | Dassault Systems[END_REF][START_REF]Connecting ecodesign with LCA for a new generation of greener products[END_REF][START_REF]GRANTA CES Edupack 2012 Overview[END_REF] in order to assist the non-environmental expert designer to eco-design his products.

Introduire la section suivante

Multi-criteria decision support methods: Overview

Multi-criteria analysis methods are decision support tools developed since the 1960s. Numerous methods are proposed to enable decision-makers to make a good «choice». Multi-criteria decisionsupport methods (MCDSM) are techniques that allow the integration of any type of criteria, these procedures seem to be more likely to lead to a judicious compromise rather than an often outdated optimum [START_REF] Mena | Introduction aux méthodes multicritères d'aide à la décision[END_REF]. MCDSM are categorized into 3 categories; single synthesis approach methods, summary overridden methods and interactive methods.

• Methods of the single criterion synthesis approach: These approaches are used in the event that the decision-maker is able to judge any pair of actions {a, b} according to one of the following cases: either a is preferred to b, or b is preferred to a, either the decision-maker is indifferent between a and b. There is therefore no incomparability between two actions. Several methods have been developed in this decision support class, which can be mentioned: Technique for Order by Similarity to Ideal Solution (TOPSIS) [START_REF] Galván B | Multiple-Objective Genetic Algorithm Using The Multiple Criteria Decision Making Method TOPSIS[END_REF]; Simple Multi-Attribute Rating Technique (SMART); Multiple Attribute Value Theory (MAVT) [START_REF] Miettinen | How to benefit from decision analysis in environmental life cycle assessment (LCA)[END_REF]; Multi Attribute Utility Theory (MAUT) [START_REF] Herath G | Analysis Evaluating public risk preferences in forest land-use choices using multi-attribute utility theory[END_REF]; Analytic Hierarchy Process (AHP) [START_REF] Saaty | Time dependent decision-making; dynamic priorities in the AHP/ANP: Generalizing from points to functions and from real to complex variables[END_REF][START_REF] Ayadi D | Une approche multicritère pour la localisation des défauts de production[END_REF][START_REF] Ayadi D | Outils multicritère d'aide à la décision pour le diagnostic des procédés industriels[END_REF].

• Methods of overridden synthesis: These approaches allow for incomparability between actions. Some are characterized by structures of preference strong, weak, indifference, incomparability. Several methods have been developed in this decision support class, which can be mentioned: Preference Ranking Organization METHod for Enrichment Evaluation (PROMETHEE) [START_REF] Azzabi L | Application de la méthode multicritère d'aide à la décision PROMETHEE pour le système HACCP[END_REF], Elimination Et Choix Traduisant la REalité (ELECTRE) [START_REF] Roy | Classement et choix en présence de points de vue multiples[END_REF]; Measuring Attractiveness by a Categorical Based Evaluation TecHnique (MACBETH) [START_REF] Bana E Costa | Macbeth (measuring attractiveness by a categorical based evaluation technique[END_REF].

• The interactive methods: These approaches are characterized by continuous interaction between the study man and the decision-maker throughout the decision-making process. reference

Overview of Micro/Macro-planning

The environmental impact assessment of the manufacturing process is the subject of numerous researches. This involves reducing or avoiding processes that have an impact on ecosystems, human health, etc. In 1995, Sheng et al. and Munoz et al. analyzed the environmental impact of different waste streams [START_REF] Sheng | Multi-objective process planning in environmentally conscious manufacturing: a feature-based approach[END_REF][START_REF] Munoz | An analytical approach for determining the environmental impact of machining processes[END_REF]. They applied a scoring system that assesses some indicators (toxicity, carcinogenetic, irritation, flammability, and reactivity) to reduce the complexity of treatment solutions through a feature-based approach. A hierarchical parts planning strategy for environmentally friendly machining is developed in [START_REF] Sheng | Hierarchical part planning strategy for environmentally conscious machining[END_REF], where it is shown that a feature can be machined with different scenarios. The aim is to choose the most impactful machining scenario. In the work of Sheng et al in 1995, the environmental impact can be calculated at the level of each feature independently of the others (micro-planning) [START_REF] Srinivasan | Feature-based process planning for environmentally conscious machining-Part 1: microplanning[END_REF]. But, obtaining microplans does not necessarily result in a globally feasible process plan for a given part. Hence, Srinivasan et al propose another approach that considers the level of a set of features that interact (macro planning) [START_REF] Srinivasan | Feature based process planning in environmentally conscious machining-Part 2: macroplanning[END_REF]. The structure of the microplanning decision model is shown in figure 2. Sormaz and Khochonovis classify the interactions between features into the three types: Shared volume by several features, tolerance/datum dependencies or coincidental/grouping relationships [START_REF] Dusan | Modeling of Manufacturing Feature Interactions for Automated Process Planning[END_REF]. In 2001, D'Souza et al., presented the microplanning, as the decomposition of machining features generated by the macroplanner into subfeatures [START_REF] Roshan | Automated Microplanning for 2.5-D Pocket Machining[END_REF]. They described the implementation of a microplanner that is capable to accomplish optimally the abovementioned tasks, either minimize time or cost for 2.5-D Pocket Machining. In 2000, Tseng and Jiang proposed a methodology which analyzes the different manufacturing costs for the different feature-based machining methods, then, the one with the lowest manufacturing cost is considered as the "best" from the manufacturing point of view [START_REF] Tseng | Evaluating multiple feature-based machining methods using an activity-based cost analysis model[END_REF]. In 2015, Gaha et al., adopted the methodology proposed by Tseng and Jiang to evaluate the environmental impact (EI) as well as cost of a part's manufacturing process till the detail design phase [START_REF] Gaha | An environmental impact/cost model for evaluating multiple feature-based machining methods[END_REF].

Proposed approach

Based on the literature review done in the previous sections, we propose our new ecomanufacturing methodology which consists in exploring both features interactions technology (FIT) and multicriteria decision support methods (MCDSM). In order to evaluate environmental impacts as well as cost, eco-design implementation must be applied [START_REF] Vukelic | ECO-DESIGN OF FIXTURES BASED ON LIFE CYCLE AND COST ASSESSMENT[END_REF]. We adopt this methodology in order to evaluate environmental impacts of a part manufacturing process till the CAD phase. Detailed methodology of eco-manufacturing is shown in figure 4.

The proposed methodology is realized through four levels:

• Level for input data • Level for scenario environmental evaluation • Level for scenario environmental selection • Level for machining planning generator Input data consists of feature recognition from the feature manager after the geometric modeling of our product using CAD software. Then, our methodology provides different process planning based on feature Interaction technology (FIT). The second level is to make the environmental evaluation for each possible scenario (based on the algorithm shown in figure 3). First of all, it chooses the environmental impacts to quantify using Evamix method. This method classifies the environmental impacts. In order to evaluate one EI in relation to another, two indices of dominance are calculated and then standardized and combined to provide an overall measure of dominance. Finally, an overall score per EI is calculated. Secondly, we implement LCA in eco-design using CAD/LCA integration systems to quantify the EIs for each possible scenario in an environmental impact matrix (figure 3).

Fig 3. Environmental impact evaluation algorithm and matrix

Where; n is the total number of possible scenarios; q is the total number of EIs to quantify; i, j are two counters and EIj (Sci) is the j-th environmental impact of the i-th scenario.

After the environmental evaluation, a selection must be done in order to choose the best compromise between different environmental impacts, i.e. the greenest scenario. Therefore, we choose PROMETHEE method to complete the comparative study of the various possible production scenarios based on equal importance for all criteria. Finally, our methodology consists of generating the machining plan related to the greenest scenario.

Case study

To validate our methodology, we consider a sample part 100mm*60mm*10mm with three holes with increasing diameters to be drilled (Figure 5). The work piece material is assumed to be AISI 4043 alloy steel with a density equivalent to 7850 kg/m³.

Three feasible sequences with feature interaction can be considered for drilling:

(A) 3 drills of the corresponding hole sizes are used. (B) The 10 mm drill is used to create a pilot hole on holes 2 and 3, then two final drills of 20 mm and 35 mm. (C) The 10 mm drill is used to make a pilot holes on holes 2 and 3, the 20 mm is used to make a pilot hole on hole 3 and finally a 35 mm is done.

Fig 5. Case study for feature interaction

For ease of calculation, the LCA is practices with the software "Bilan Produit", developed by ADEME [START_REF]Bilan Produit[END_REF].The database used is developed in collaboration with EcoInvent Center and the Swiss Center for life cycle inventories [START_REF] Frischknecht | Overview and methodology[END_REF].By using CML method [START_REF] Deja | Featurebased generation of machining process plans for optimised parts manufacture[END_REF], 8 environmental impacts are considered [EI1= Energy consumption (MJ eq) , EI2=Resource consumption (kg Sb eq), EI3=Greenhouse effect GWP 100 mod (kg CO2 eq), EI4=Acidification (kg SO2 eq), EI5= Eutrophication (air water soil) ( kg PO4 ---eq), EI6=Photochemical pollution (kg C2H4), EI7 = Aquatic ecotoxicity (kg 1,4-DB eq), EI8 = Human toxicity (kg 1.4-DB eq)]. At the scenario environmental evaluation level, a CAD/LCA integration system is used to calculate the EIs for each possible machining scenario and the process outputs are shown in figure 6.

Conclusion

This paper is developed base on the work of [START_REF] Vukelic | ECO-DESIGN OF FIXTURES BASED ON LIFE CYCLE AND COST ASSESSMENT[END_REF]. It presents and discusses the need for integrating environmental performances into manufacturing process based on feature interactions technology and MCDSM in order to optimize the manufacturing part process in terms of environmental impact (such as energy consumption, CO2 emission, cutting fluids, etc.) till detail design phase. A methodology for analyzing different manufacturing environmental impacts was proposed using an activity-based FIT/MCDSM model. Future works should focus on detailing the FIT-based process sequences generator and since cost constraint is a priority for manufacturers, the establishment of a methodology based on a good environment/cost compromise could attract their attentions.

Fig 2 .

 2 Fig 2. Schematic of the microplanning algorithm [75]

Fig 4 .

 4 Fig 4. A new based feature-interaction eco-manufacturing methodology on CAD phase

Fig. 6 Fig 7 .

 67 Fig.6 Case study results matrix


Emanuela Boros

Luis Adrián Cabrera-Diego

Antoine Doucet

Experimenting with Unsupervised Multilingual Event Detection in Historical Newspapers

Keywords: Event detection, Named entity recognition, Historical documents, Historical newspapers

To prevent historical knowledge's fading, research in event detection could facilitate access to digitized collections. In this paper, we propose a method for annotating multilingual historical documents for event detection in an unsupervised manner by leveraging entities and semantic notions of event types. We automatically annotate the documents by relying on dependency parse trees and automatic semantic mapping to event-based frames, with a focus on the multilingual transfer between frames and candidate events. The documents are afterward verified by native speakers, Digital Humanities researchers. We also report on experimental results of event detection in historical newspapers with a state-of-the-art model. We demonstrate that our approach allows for easy language adaptation by presenting two study cases with knowledge extracted from German newspapers from 1911 to 1933 regarding events surrounding International Women's Day and from French newspapers between 1900 and 1944 related to the abolition of guillotine executions in France. Our preliminary findings show that this type of approach could alleviate the need for manual annotation by also providing a practical course of action toward unsupervised event detection from multilingual digitized and historical documents.

Introduction

The digitization of newspapers has greatly improved accessibility and clearly changed the nature of historical research, by enabling easier data access and analysis at scale through multilingual semantic data enrichment [START_REF] Boschetti | Computational analysis of historical documents: An application to Italian war bulletins in World War I and II[END_REF][START_REF] Rovera | Event-Based Access to Historical Italian War Memoirs[END_REF][START_REF] Cybulska | Historical event extraction from text[END_REF][START_REF] Boschee | Automatic extraction of events from open source text for predictive forecasting[END_REF]. Through better document analysis results and semantic enrichment e.g., named entity recognition (NER), relation extraction (RE), event extraction (EE), the quality of the newspaper data offered by the libraries to its users is substantially improved [START_REF] Ehrmann | Introducing the clef 2020 hipe shared task: named entity recognition and linking on historical newspapers[END_REF][START_REF] Ehrmann | Overview of clef hipe 2020: Named entity recognition and linking on historical newspapers[END_REF][START_REF] Ehrmann | Introducing the hipe 2022 shared task: Named entity recognition and linking in multilingual historical documents[END_REF][START_REF] Ehrmann | Overview of HIPE-2022: Named Entity Recognition and Linking in Multilingual Historical Documents[END_REF]. Preserving the historical memory of entities and events from historical documents and making them accessible to a larger audience, not only limited to humanities scholars and experts, could lead to better organization of our historical knowledge [START_REF] Shaw | Events and periods as concepts for organizing historical knowledge[END_REF][START_REF] Bedi | Event timeline generation from history textbooks[END_REF][START_REF] Oberbichler | Integrated interdisciplinary workflows for research on historical newspapers: Perspectives from humanities scholars, computer scientists, and librarians[END_REF]. Following this statement, this process can be viewed as an area where the detection of events in historical documents can contribute to the construction of more nuanced knowledge bases that could enable further data exploration and help to shape the humanities and historians' research [START_REF] Oberbichler | Integrated interdisciplinary workflows for research on historical newspapers: Perspectives from humanities scholars, computer scientists, and librarians[END_REF]. Extracting event information from text documents into a structured knowledge base or ontology enables several technologies. For example, text summarization might benefit from the selection of one or more events to yield the best summary with the least extraneous information [START_REF] Filatova | Event-based extractive summarization[END_REF][START_REF] Liu | Extractive summarization based on event term clustering[END_REF]. Question answering can take advantage of the detected events and they will be able to answer queries about types of events (wars, disease outbreaks, political movements, climate catastrophes, terrorist attacks, etc.) [START_REF] Saurí | Evita: A robust event recognizer for QA systems[END_REF][START_REF] Liu | Event extraction as machine reading comprehension[END_REF].

Therefore, for enabling the development and evaluation of event detection in historical documents, benchmarking plays an important role. However, most of the current datasets in event detection (i.e., MUC [START_REF] Grishman | Message understanding conference-6: A brief history[END_REF], ACE 2005 [START_REF] Walker | ACE 2005 multilingual training corpus[END_REF]) are not suitable for several reasons, including the high cost of manual annotation of historical texts and the difficulty in defining an event [START_REF] Sprugnoli | Event Detection and Classification for the Digital Humanities[END_REF]. Besides, different studies have explored how different natural language processing (NLP) tasks, such as named entity recognition (NER) [START_REF] Miller | Named entity extraction from noisy input: speech and ocr[END_REF][START_REF] Boros | Alleviating digitization errors in named entity recognition for historical documents[END_REF][START_REF] Rodriquez | Comparison of named entity recognition tools for raw OCR text[END_REF][START_REF] Hamdi | An analysis of the performance of named entity recognition over ocred documents[END_REF] and entity linking (EL) [START_REF] Van Strien | Assessing the impact of OCR quality on downstream NLP tasks[END_REF][START_REF] Mutuvi | Evaluating the impact of ocr errors on topic modeling[END_REF], can be impacted by the digitization process. However, to the best of our knowledge, there are no previous works regarding this type of analysis for the event detection task, mostly because there is no data.

Thus, in this paper, we develop a method to automatically discover a set of distinct, salient events from historical newspapers. This is done by leveraging the semantic similarity of contextual representations for detecting event triggers in an unsupervised manner that can be easily adaptable to other languages. The detected events can be used then to speed up the manual annotation or validation of historical corpora.

Event Detection in Modern and Historical Datasets

Event Detection in Modern Datasets Prior work in event detection can be divided in: pattern-based systems [START_REF] Riloff | Automatically generating extraction patterns from untagged text[END_REF][START_REF] Riloff | An empirical study of automated dictionary construction for information extraction in three domains[END_REF][START_REF] Yangarber | Automatic acquisition of domain knowledge for information extraction[END_REF], machine learning systems based on engineered features (i.e. feature-based) [START_REF] Huang | Peeling back the layers: Detecting event role fillers in secondary contexts[END_REF][START_REF] Hong | Using cross-entity inference to improve event extraction[END_REF][START_REF] Li | Joint event extraction via structured prediction with global features[END_REF][START_REF] Bronstein | Seed-based event trigger labeling: How far can event descriptions get us?[END_REF], and neural-based approaches [START_REF] Chen | Event extraction via dynamic multipooling convolutional neural networks[END_REF][START_REF] Nguyen | Event detection and domain adaptation with convolutional neural networks[END_REF][START_REF] Nguyen | Joint event extraction via recurrent neural networks[END_REF][START_REF] Feng | A language-independent neural network for event detection[END_REF]. There also has been a lot of interest in approaching this task with external resource-based models which are either feature-based [START_REF] Liu | Leveraging framenet to improve automatic event detection[END_REF][START_REF] Li | Joint event extraction based on hierarchical event schemas from framenet[END_REF] or neuralbased [START_REF] Liu | Exploiting argument information to improve event detection via supervised attention mechanisms[END_REF] combined with resources such as FrameNet [START_REF] Baker | The Berkeley FrameNet project[END_REF] which is a linguistic corpus that defines complete semantic frames and frame-to-frame relations, or event data generation as in [START_REF] Yang | Exploring pre-trained language models for event extraction and generation[END_REF][START_REF] Zhang | Joint entity and event extraction with generative adversarial imitation learning[END_REF][START_REF] Hong | Self-regulation: Employing a generative adversarial network to improve event detection[END_REF]. The approach proposed in [START_REF] Liu | Leveraging framenet to improve automatic event detection[END_REF] used a probabilistic soft logic (PSL) based approach and a neural network by also leveraging FrameNet to alleviate the data sparseness problem of event detection based on the observation that frames in FrameNet are analogous to events. The authors of [START_REF] Liu | Exploiting argument information to improve event detection via supervised attention mechanisms[END_REF] also consider that arguments provide significant clues to this task, and adopt a supervised attention mechanism to exploit argument information explicitly for event detection, while also using events from FrameNet, as extra training data.

The model described in [START_REF] Li | Joint event extraction based on hierarchical event schemas from framenet[END_REF] also leverages FrameNet by tackling the challenge of the annotation cost and data scarcity by considering that ACE 2005 dataset defines limited and specific event schemes based on FrameNet by expressing event information with frame and building a hierarchy of event schemas that are more fine-grained and have much wider coverage than ACE.

Event Detection in Historical Datasets When it comes to historical and digitized documents, models rely more on external resources, such as FrameNet and WordNet [START_REF] Fellbaum | Wordnet. In: Theory and applications of ontology: computer applications[END_REF], than on event detection approaches used in the state of the art for modern datasets. FrameNet, for instance, has been highly investigated for event detection in historical and digitized, mostly due to the lack of annotated data. A project proposed in 2004 [START_REF] Ide | Exploiting semantic web technologies for intelligent access to historical documents[END_REF] involved the enhancement of materials drawn from the Franklin D. Roosevelt Library and Digital Archives and enabled data exploitation for providing a deeper search and access methods for historians of World War II. The documents were scanned, hand-validated, and enriched with various entities such as person names, dates, locations, and job titles. The work focused on the identification of communicative events in the Memorandum of conversation and implied the extraction of verbs associated with any of the FrameNet "Communication" frames and this communicative event utilized a scheme that assigned the role of communicator to a tagged person or pronoun preceding the verb. Another historical event detection module was proposed to be used for museum collections [START_REF] Cybulska | Historical event extraction from text[END_REF], allowing users to search for exhibits related to particular historical events or actors within time periods and geographic areas, extracted from Dutch historical archives. The authors focused on event detection from manually tagged textual data about the Srebrenica Massacre (July 1995). They specified event triplets and Wordnet concepts denoting event actions, participants, and locations or time markers and identified the historical events through recognition of historical actions. A novel FrameNet-based method was also proposed for performing a computational analysis of Italian war bulletins in World War I and II [START_REF] Boschetti | Computational analysis of historical documents: An application to Italian war bulletins in World War I and II[END_REF] that had never been digitized before. The bulletins were annotated with different types of information, such as named entities, events, participants, time, and georeferenced locations. Instances of major event types (e.g., bombing, sinking, battles) were established before applying the FrameNet mapping [START_REF] Ide | Exploiting semantic web technologies for intelligent access to historical documents[END_REF].

Data Collection

For the data collection and our experiments, we utilized the NewsEye collection3 that consists of a large selection of European newspapers (1850-1950) in several languages that have been digitized and made available online. The difficulty of detecting events in the NewsEye dataset does not only refer to the automatic text recognition (ATR) or digitization errors, but also to the lack of annotated data in a multilingual setting.

Thus, we decided to annotate two subsets of documents in two low-resource languages, German and French, and to experiment with a state-of-the-art event detection system in a domain and language adaptation scenario. The documents were collected using the NewsEye platform [START_REF] Jean-Caurant | Accessing and investigating large collections of historical newspapers with the newseye platform[END_REF], and annotated by the Digital Humanities groups (native speakers) from the NewsEye consortium, University of Innsbruck (UIBK-ICH), Austria, and the Paul Valéry University Montpellier 3, France. The subjects of the datasets were selected by the annotators, depending on their line of research and interests.

Unsupervised Data Annotation

Following the recommendation of Sprugnoli, [START_REF] Sprugnoli | Event Detection and Classification for the Digital Humanities[END_REF], in this work, we defined an event to be consistent with ACE 2005 [START_REF] Walker | ACE 2005 multilingual training corpus[END_REF] and chose the event types and subtypes according to their annotation guidelines4 . We then automatically assigned a frame category to each event type by consulting the English FrameNet database. FrameNet, as indicated in Section 2, is a linguistic corpus containing considerable information about lexical and predicate-argument semantics in the form of frames. A frame, in FrameNet, is defined as a triplet composed of a name, like Execution, a set of Frame Elements (FEs), and a list of Lexical Units (LUs). 5 An LU is a word or phrase that evokes the corresponding frame, such as executioner and guillotine. FEs indicate a set of semantic roles associated with the frame, such as reason, instrument or place. Most frames contain a set of exemplars with annotated LUs and FEs.

For linking ACE 2005 event subtypes to FrameNet frames, we start by processing the corpus by extracting all the verbs of the corpus and grouping them using WordNet [START_REF] Fellbaum | Wordnet. In: Theory and applications of ontology: computer applications[END_REF] synsets. Then, the grouped verbs are matched to FrameNet lexical units (LU). Finally, we associate different ACE 2005 event subtypes 6 to FrameNet by matching frames names to the event subtype names as in [START_REF] Li | Joint event extraction based on hierarchical event schemas from framenet[END_REF]. In summary, ACE 2005 event subtypes, are linked indirectly to FrameNet lexical units (LU), which in turn can be seen as event triggers.

For the creation of candidate event mentions, we generate dependency parse trees for each sentence in the dataset 7 . Next, we focus on the extraction of nounphrases (NPs) that can be pronouns, proper nouns, or nouns, potentially bound with other tokens that act as modifiers, e.g., adjectives or other nouns, that are generally subjects (nsubj ) or objects (obj ) (complements of prepositions). Finally, we obtain a triplet composed of the tree root, which is generally the verb of the sentence, and its dependents, the nsubj and the obj. A candidate event mention is, thus, represented by a triplet, where the root is commonly a verb, which can possibly be mapped to a lexical unit (LU), similarly as we did for the event trigger candidates. In Figure 1, we present the dependency parse tree of a sentence in French. For example, in Figure 1, there are two triplets both with "disparaître" (to disappear) as root. Specifically, the first triplet is composed of j' as subject (subj) and "Danton" as object (obj). The second triplet has for subject (subj) j' and for object (obj) "Robespierre". In both triplets, "Danton" and "Robespierre", besides being objects, they are entities of type person.

For linking candidate event mentions to ACE 2005 event subtypes, we make use of multilingual BERT [START_REF] Devlin | Bert: Pre-training of deep bidirectional transformers for language understanding[END_REF]. To be precise, we use BERT to obtain the contextual representation x of each token in every sentence in the corpus having at least one candidate event mention; X = [x 0 , x 1 . . . x n ] where n is the sentence length. Then, from X, we isolate the contextual representation x i of the token i that represents the candidate root event mention. For example, the first "disparaître" from Figure 1.

At the same time, we use as well BERT to obtain the contextual representation of the ACE 2005 event subtype by processing FrameNet lexical units (LU) associated, in step 1 as event triggers, for each explored event subtype. Specifically, for a specific event subtype, we concatenated all its event triggers, i.e. lexical units, to generate a pseudo-sentence that is processed by BERT. Then BERT outputs a contextual embedding of the pseudo-sentence, which represents the event subtype. 8Finally, in order to consider a candidate event mention, we compare, through cosine similarity, the contextual embedding of an ACE 2005 subtype, with the one of the root of the event mention candidate. If the obtained cosine similarity is greater than 0.7, then the mention candidate is considered to belong to the analyzed ACE 2005 subtype.

For example, for the Attack event type in French, we compared the extracted roots with the following set of lexical units that was retrieved from FrameNet: attack, assault, strike, ambush, assail, raid, bomb, bombing, raid, infiltrate, hit, fire, small, take up arms, fire, airstrike, bombardment, counter-attack, counteroffensive. After analyzing the results, we observed that two separate sets of event triggers were extracted: (1) known events: foudroyer (strike down), armer (take up arms), attaquer (attack), frapper (strike); (2) unseen events: arracher (snatch), déchiqueter (tear off), étouffer (suffocate), empoigner (grab), trancher (shred).

Evaluation

As indicated in Section 2, there is no annotated data for historical event detection, and its creation can be expensive. Thus, to evaluate the unsupervised annotation (Section 4), we rely on an indirect assessment based on a fine-tuned language model. Specifically, we train an event detection system by fine-tuning multilingual BERT [START_REF] Devlin | Bert: Pre-training of deep bidirectional transformers for language understanding[END_REF] on English ACE 2005 following the work of Boros et al. [START_REF] Boros | Event detection with entity markers[END_REF]. The goal is that through zero-shot 9 , the event detection system will be able to detect a subset of events in the historical corpus (Section 3), which would intersect with those found by the unsupervised method (Section 4). Ideally, the spans of tokens found by the fine-tuned model should match the spans set by the unsupervised annotation, and thus, we will be able to determine precision, recall, and F-score.

As well, following the work of Boros et al. [START_REF] Boros | Event detection with entity markers[END_REF], we explore for our evaluation, the fine-tuning of multilingual BERT on English ACE 2005 along with entity markers. The use of entity markers consists in augmenting the input data with a series of special tokens that include the entity type. For example, the sentence from Figure 1 becomes From the same place where I had seen [P ER start ] Danton [P ER end ] disappear, I saw [P ER start ] Robespierre [P ER end ] disappear. To do this, we train beforehand a NER system based on a hierarchical architecture that includes a stack of Transformer layers [START_REF] Vaswani | Attention is all you need[END_REF] on top of a BERT encoder (BERT-n×Transformer-CRF). This architecture, described in [4], has proved to be robust against OCR errors. The performance of the NER system on this collection is, in terms of F-score 48.32 for German, and 72.71 for French. Once the NER system has been created, we annotate the historical corpus and add the entity markers to the input of the event detection system.

Results and Discussion

We present the results obtained through two study cases defined by researchers from the NewsEye project and then, we discuss these results. International Women's Day For this study case, we selected a subset of 207 German articles that mentioned the keyword "Women's Day" ("Frauentag") and "International Women's Day" ("Internationaler Frauentag") published between 1911 and 1933 in order to analyze the events organized on or around the International Women's Day. For this subset, we selected events regarding gatherings or movements. These are revealed by the Conflict event type with the Demonstrate and Attack subtypes and the Contact with Meet event subtype.

To understand the meaning of the event types in a deeper analysis, we detail several types in the following paragraphs. Demonstrate and Attack are subtypes of the Conflict event type. An Attack event is defined as a violent physical act causing harm or damage. For example, in Um diesen ersehnten Zustand herbeizuführen, entsenden wir unseren Schwestern in der ganzen Welt unsere Grüße und rufen sie auf, beim internationalen Frauentag mit uns gemeinsam gegen die Fortdauer des Krieges zu demonstrieren. 10 , the triggers are: for Demonstrate, demonstrieren, and for Attack, Krieges. Thus, there are, in this case, two mentions of different types of events. We can observe from Table 1 that in the results for the model that does not utilize entity markers, the performance drops significantly, while their presence increases the scores values.

Death Penalty Abolition In the 1900s, in France, there were regular debates regarding the abolition of the death penalty. For this study case, we selected a subset of 207 French articles that mentioned "guillotine" (same in French) and "death penalty" ("peine de mort") published between 1900 and 1944. from the following newspapers: Le Matin, L'OEuvre and Le Gaulois. We selected events regarding life, through the Die event subtype, conflictual events (Conflict with the Attack subtype), and criminal Justice events with Execute subtype. Due to the digitization and article separation processes, some articles contained an insignificant amount of tokens, thus, we removed those with less than ten tokens 11 .

The results, summarized in Table 2, reveal the capacity of our approach for extracting events while establishing a strong baseline. However, we notice that the scores are rather imbalanced, favoring precision, which could indicate a close similarity between the chosen event types.

Discussion It must be stated that the low F-scores (Tables 1 and2) for certain event subtypes are not unexpected. In the first place, we compare two approaches in an indirect way, one using an unsupervised method, and another using a supervised method but trained on different types of documents and language. As well, the results of the NER system are not perfect, especially for German, which could affect their performance. Nonetheless, the results presented in Tables 1 and2, show that there is an intersection between the unsupervised annotations and those predicted by the fine-tuned models. Thus, this can signal that the unsupervised approach presented here could be useful for pre-annotating historical documents before being seen by a human. This could accelerate the creation of actual corpora annotated with events and, in the future, automatize the detection of events through machine learning. However, it is clear that the unsupervised method has some limitations. We need to evaluate how well the semantics could have affected the matching of verbs and lexical units in FrameNet, if these mistakes are, for example, the reasons why certain events were not detected in French, as the low recall shows in Table 2.

Conclusions

In this paper, we proposed an unsupervised event detection method for detecting events in historical newspapers by relying on available resources. We also obtained promising preliminary results in event detection from multilingual articles surrounding International Women's Day in German, and the death penalty abolition, in French. We plan in making the dataset publicly available for enabling further research, while envisioning subsequent work regarding an enhanced list of event types and studies concerning the adaptability to other languages.

Fig. 1 .

 1 Fig. 1. Example of the correspondence between syntactic arguments of the verbs and participants of the event denoted by the verb (Translation: From the same place where I had seen Danton disappear, I saw Robespierre disappear.)

Table 1 .

 1 Evaluation of NewsEye German event detection.

	Type	Subtype	P	R	F1
		BERT-multilingual-cased
	Conflict	Attack	33.33 4.55 8.00
	Conflict	Demonstrate	50.00 9.09 15.38
	Contact	Meet	50.00 15.38 23.53
			44.44 9.65 15.63
		BERT-multilingual-cased+Entity Type Markers
	Conflict	Attack	27.27 42.86 33.33
	Conflict	Demonstrate	47.06 66.67 55.17
	Contact	Meet	83.33 38.46 52.63
			52.55 49.33 47.04

Table 2 .

 2 Evaluation of NewsEye French event detection.

	Type	Subtype	P	R	F1
		BERT-multilingual-cased
	Conflict	Attack	13.31 18.22 15.41
	Life	Die	42.30 19.60 26.83
	Justice	Execute	40.00 10.00 16.00
			31.87 15.94 19.40
		BERT-multilingual-cased+Entity Type Markers
	Conflict	Attack	20.10 18.21 19.21
	Life	Die	30.82 21.41 25.30
	Justice	Execute	100.0 15.00 26.08
			50.30 18.20 23.53

https://www.newseye.eu/

https://www.ldc.upenn.edu/sites/www.ldc.upenn.edu/files/ english-events-guidelines-v5.4.3.pdf

An example of the Execution frame can be viewed at Framenet2 website.

We chose movements, conflictual events, and membership in organizations.

We used spaCy 3.1+[START_REF] Honnibal | spaCy: Industrial-strength Natural Language Processing in Python[END_REF] with the model xx ent wiki sm https://spacy.io/models/ xx.

We are aware that BERT was trained for representing true sentences rather than pseudo-sentences. However, we consider that BERT might generate an embedding that represents the context in which all the event triggers are frequently used.

As we use multilingual BERT, even when the training is English, the model should be able to predict events in other languages in a zero-shot manner.

Translation: In order to bring about this desired state, we send our greetings to our sisters all over the world and call on them to demonstrate together with us against the continuation of the war on International Women's Day.

This threshold was chosen experimentally after we verified the dismissed articles.

Acknowledgments

This work has been supported by the European Union's Horizon 2020 research and innovation program under grants 770299 (NewsEye) and 825153 (Embeddia). Also, it has been supported by the ANNA (2019-1R40226) and TERMITRAD (2020-2019-8510010) projects funded by the Nouvelle-Aquitaine Region, France.