A key to solar cells with lower environmental impact is higher efficiency and reduced material usages. Bifacial solar cells may have a higher efficiency as light can enter from two directions and tandem solar cells may use a larger part of the incoming solar spectrum, increasing the efficiency. However, both these applications require transparent and conducting contacts. This thesis aimed to investigate how suitable the transparent conductive oxides aluminum doped zinc oxide (AZO) and indium doped tin oxide (ITO) are as contacts in bifacial CIGS cells or CIGS/Silicon tandem cells. The contacts must remain stable when CIGS is deposited on top of it, meaning that they have to endure first 500°C and then 600°C in combination with copper, indium, gallium and selenium vapours. A thin layer of AZO topped with ITO and pure ITO films of different thicknesses were deposited by RF- and DC-sputtering, varying the oxygen flow. Opto-electrical characterization showed that the transparency in the infrared was balanced against high conductivity due to a shift in the plasmon peak's position. No great difference was seen between pure ITO samples and AZO/ITO samples, so only the first where further processed. The ITO films were annealed to 500°C in the CIGS deposition chamber, exposed to selenium vapour. The films' sheet resistances dropped drastically, which was mainly attributed to activation of tin donors. ITO produced with low oxygen flows also appeared more crystalline according to x-ray diffraction measurements. Photon absorption in the ITO was used to estimate the current loss in bifacial and tandem applications and graphs with current loss and sheet resistance can be used to select an ITO deposition process. Commercial ITO was exposed to 100s of the CIGS deposition process but only during selenium and gallium vapour. A layer of gallium selenide could be identified on the surface, but the ITO appeared to remain stable. Sodium fluoride pre deposition treatment lowered the samples absorption for all wavelengths compared to non-treated samples.

A presente tese fornece um primeiro quadro arqueológico para a ocupação pré-cerâmica da Região Cárstica do Alto São Francisco, uma área com cerca de 1500 km² localizada no centro-oeste de Minas Gerais, baseando-se na análise de sete elementos: cronologia (relativa e absoluta), tecnologia lítica, subsistência (fauna), sepultamentos, mobilidade, uso do espaço em cavidades naturais e arte rupestre. Os registros e amostras mais significativos foram obtidos em sondagens e escavações realizadas por níveis arbitrários de 10 cm em quatro sítios em cavidade natural de calcário, totalizando 28m² de área aberta em 11 setores, todos eles situados na área abrigada a partir da linha de goteira para dentro, com destaque, em termos de superfície aberta, para a Gruta do Marinheiro (20m²). Após a análise dos diferentes tipos de evidências por nível, setor e sítio, foi realizada uma síntese onde foram enfocadas as mudanças verticais ou diacrônicas, de origem quantitativa e/ou qualitativa, ao longo dos níveis arbitrários, permitindo observar eventuais tendências, rupturas ou transformações. As variações horizontais ou sincrônicas intra- e intersítio também foram consideradas à luz das diferenças entre os setores escavados. A partir da análise dos sete elementos supracitados obteve-se, de forma resumida, o seguinte quadro geral: observa-se uma ocupação intensa dos abrigos naturais por grupos humanos nos primeiros três mil anos do Holoceno na região (de cerca 10,2 a 7,2 mil anos AP), apresentando uma indústria lítica lascada e bruta com instrumentos tanto bifaciais quanto unifaciais, padronizados ou não. Praticavam uma caça generalizada com destaque para mamíferos de pequeno e médio porte, uma pesca/coleta de peixes não-migradores como os siluriformes (mandi, bagre, etc.) e uma coleta de caramujos gigantes (Gastrópoda). Produziram sepultamentos com padrões diferenciados, conforme também foi observado em outros sítios abrigados de Minas Gerais para o período paleoíndio. Exerciam uma alta mobilidade em que ocupavam os espaços de uma variedade de abrigos naturais, localizados em todos os compartimentos topográficos do carste, de forma padronizada (no total 27 sítios pré-cerâmicos sob abrigo natural foram contemplados). Não restringiam seus movimentos, provavelmente sazonais, apenas a este ambiente como demonstram vestígios 24 encontrados por arqueólogos amadores nas margens do Lago de Furnas (cerca de 80 km a SW do carste). Existem, enfim, indícios circunstanciais para que esses grupos sejam associados à tradição rupestre Planalto. No final argumenta-se pela existência de algumas semelhanças e paralelos com a região de Lagoa Santa, situada 200 km a NE (em linha reta) da região em estudo. / This thesis brings a first archaeological framework for the pre-ceramic occupation of a carstic area situated in the upper São Francisco river valley, also known as the Pains region, with an area of about 1500 km², in the central-western portion of the state of Minas Gerais, Brazil. This was done by the study of seven elements related to these populations: chronology (relative and absolute), technology (lithic and bone), subsistence (faunal remains), burials, mobility, use of space in rock-shelters and rock-art. The most relevant findings were made in excavations and test-pits by artificial levels of 10 cm in four limestone rock-shelter sites, distributed in eleven different places or sectors, all of them from the drip-line to the interior of the shelters, with a total area of 28m². The most important site is the \"Gruta do Marinheiro\" cave, where 20m² were excavated. After the analysis of the different types of materials by level, sector and site, the quantitative and qualitative vertical changes were studied in search for tendencies, ruptures and/or transformations. The horizontal variations between sectors were also observed. These analysis showed that the rock-shelters were intensely occupied in the first three millennia of the Holocene, between ca. 10200 and 7200 years BP, associated with an unifacial and bifacial lithic industry and faunal remains, indicating they hunted small and middle-sized mammals, fished mainly Siluriformes and gathered Gastropoda. They buried their dead in a variety of manners, in patterns that are also seen in other rock-shelters of Minas Gerais associated with the paleo-indian occupation. Looking at 27 known rock-shelters in the region with pre-ceramic evidence, it was also possible to see that they were present in all main topographical areas of this limestone region, indicating a high mobility within it, but also showing some connections with areas outside, as seen by very similar lithic material found by amateurs in the \"Lago de Furnas\" area (80 km to the SW). There is also circumstantial evidence that could relate these groups to the \"Planalto\" rock-art tradition. Finally we argue that there are many elements that put the Pains region close archaeologically to the better-known Lagoa Santa region, situated 200 km to the NE.

The aim with this project was to study the power output from a frameless bifacial photovoltaic (PV) system relative to a traditional monofacial PV system with a frame. A general overview of how the geographical conditions affects the energy utilization of different PV systems is investigated throughout the project. Also, the study examined if further comparisons and evaluations, between PV systems, can be better established. The two examined solar parks, installed under different conditions, are located in Uppsala and Enköping, Sweden. In order to fulfill the aim and compare the different PV systems, three cases were analyzed. To increase the credibility of a comparison between the two cities, a sensitivity analysis considering the weather condition was executed. In case one, the result indicates that a bifacial panel is 5.2% and 3.6% more advantageous than a traditional monofacial panel during summer and winter, respectively. In case two, the frameless, more tilted and elevated bifacial panel is 58% and 680% more advantageous than a traditional monofacial panel during summer and winter, respectively. Also, in case three, the frameless, more tilted and elevated bifacial panel is 19% and 76% more advantageous than a bifacial panel with frame during summer and winter, respectively. When installing a new solar park, it is important to consider the location’s specific features since these affects the energy yield of the PV system. Future installations, which are installed with the intention to evaluate certain properties, is suggested to be installed with more initially comparable conditions in mind.

Le modèle « Out of Africa » est profondément ancré dans les réflexions portant sur les peuplements paléolithiques. Pour le Pléistocène inférieur et moyen ancien, plusieurs vagues de dispersion des premiers hominidés à partir de l’Afrique de l’Est sont avancées, en particulier vers le Proche-Orient sur la base de trois sites majeurs : Dmanisi, ‘Ubeidiya et Gesher Benot Ya‘aqov. Cette théorie véhicule également l’idée d’imports répétés de techniques nouvelles, notamment le façonnage bifacial.Cependant, une déconstruction des mécanismes inhérents à ce modèle permet d’identifier des obstacles conceptuels et méthodologiques issus du « paradigme de la flèche », simplifiant et réduisant la complexité des phénomènes techniques et culturels.Afin de réintégrer à la question l’espace et le temps, dont l’absence au sein d’« Out of Africa » est rédhibitoire, nous utilisons une vision évolutive des techniques basée sur des réflexions de philosophie, d’ergonomie et de géographie. Cette vision, reprise par des paléolithiciens depuis une quinzaine d’années, a conduit à concevoir une méthodologie techno-fonctionnelle centrée sur les notions d’outil, de geste et de fonctionnement.Une étude approfondie utilisant cette approche a été menée sur quatre assemblages est-africains et proche-orientaux, complétée par des observations portant sur trois autres collections. Les informations obtenues permettent de discuter des processus d’évolution technique sur le temps long, de proposer une vision alternative des peuplements qui considère en particulier l’idée d’inventions du façonnage bifacial indépendantes, et enfin d’envisager des espaces culturels à différentes échelles de temps et d’espace. / The “Out of Africa” model is deeply rooted in the issues of Paleolithic settlement. For the Lower and Early Middle Pleistocene, several waves of early hominid dispersal from Africa have been proposed, especially to the Near East on the basis of three major sites: Dmanisi, ‘Ubeidiya and Gesher Benot Ya‘aqov. This theory also conveys the idea of repeated imports of new techniques, including bifacial shaping.However, the mechanisms inherent in this model are deconstructed: it allows to identify conceptual and methodological obstacles from the “arrow paradigm”, which simplifies and reduces the complexity of technical and cultural phenomena.The absence of space and time in the “Out of Africa” model is a crippling flaw. To reintroduce these dimensions in the debate, an evolutionary view of technics is used and is inspired by thoughts from philosophy, ergonomics and geography. In Paleolithic prehistory, this point of view, developed over past fifteen years, led to work out a techno-functional methodology focused on notions of tool, gesture and functioning.A detailed study using this approach was conducted on four assemblages from East Africa and Near East, with some supplementary observations on three other collections Then a discussion is offered on various topics: (1) the processes of technical evolution over long time, (2) an alternative vision of settlements, which particularly considers the idea of independent inventions of bifacial shaping, and finally (3) the ability to define cultural spaces on different scales of time and space.

This article presents key data and discussion about the initial peopling of northwestern South America, highlighting its strategic significance in the continental context, cultural variability and landscape change over time. In Colombia there is very little relevant information regarding occupations prior to 12,000 BP; in contrast, the information is abundant relative to a number ofearly contexts during the Pleistocene-Holocene transition. The variability among unifacial and bifacial lithic assemblages reported in different physiographic regions indicates alternative models on early settlement to regional level. Considering the importanceof the inter-Andean valley of the Magdalena River, this article emphasizes the archaeological contexts and paleoenvironmental information, highlighting environmental impacts associated not only to global climate change, but in particular of the effects ofvolcanism. The article stresses the findings and chronologies of bifacial lithic assemblages of the Magdalena Valley in relation to the early archaeology of northwestern South America. / En este artículo se presentan los principales datos y reflexiones asociados al poblamiento inicial del noroccidente de Sudamérica debido a su significado estratégico en el marco continental, se destacará la variabilidad cultural y se enfatizarán los cambios depaisajes en el transcurso del tiempo. En Colombia existe muy poca información relevante relacionada con las ocupaciones anterioresa 12.000 AP; en contraste, la información es abundante en cuanto al número de contextos tempranos durante la transición Pleistoceno-Holoceno. La variabilidad entre los conjuntos líticos unifaciales y bifaciales reportados en distintas regiones fisiográficas plantea propuestas de modelos alternativos sobre el poblamiento temprano a escala regional. Considerando la importancia del valle interandino del río Magdalena, se recalcan los contextos arqueológicos e información paleoambiental. Asimismo, se destacan los impactos ambientales que demuestran por qué no perduraron las evidencias del Pleniglacial, lo que podría deberse a efectos asociados no solo al cambio climático global, sino, en particular, a causa del vulcanismo. Este trabajo resalta los hallazgos y cronologías de los conjuntos líticos bifaciales del valle del Magdalena en relación con la arqueología temprana del noroccidente de Sudamérica.

A presente tese fornece um primeiro quadro arqueológico para a ocupação pré-cerâmica da Região Cárstica do Alto São Francisco, uma área com cerca de 1500 km² localizada no centro-oeste de Minas Gerais, baseando-se na análise de sete elementos: cronologia (relativa e absoluta), tecnologia lítica, subsistência (fauna), sepultamentos, mobilidade, uso do espaço em cavidades naturais e arte rupestre. Os registros e amostras mais significativos foram obtidos em sondagens e escavações realizadas por níveis arbitrários de 10 cm em quatro sítios em cavidade natural de calcário, totalizando 28m² de área aberta em 11 setores, todos eles situados na área abrigada a partir da linha de goteira para dentro, com destaque, em termos de superfície aberta, para a Gruta do Marinheiro (20m²). Após a análise dos diferentes tipos de evidências por nível, setor e sítio, foi realizada uma síntese onde foram enfocadas as mudanças verticais ou diacrônicas, de origem quantitativa e/ou qualitativa, ao longo dos níveis arbitrários, permitindo observar eventuais tendências, rupturas ou transformações. As variações horizontais ou sincrônicas intra- e intersítio também foram consideradas à luz das diferenças entre os setores escavados. A partir da análise dos sete elementos supracitados obteve-se, de forma resumida, o seguinte quadro geral: observa-se uma ocupação intensa dos abrigos naturais por grupos humanos nos primeiros três mil anos do Holoceno na região (de cerca 10,2 a 7,2 mil anos AP), apresentando uma indústria lítica lascada e bruta com instrumentos tanto bifaciais quanto unifaciais, padronizados ou não. Praticavam uma caça generalizada com destaque para mamíferos de pequeno e médio porte, uma pesca/coleta de peixes não-migradores como os siluriformes (mandi, bagre, etc.) e uma coleta de caramujos gigantes (Gastrópoda). Produziram sepultamentos com padrões diferenciados, conforme também foi observado em outros sítios abrigados de Minas Gerais para o período paleoíndio. Exerciam uma alta mobilidade em que ocupavam os espaços de uma variedade de abrigos naturais, localizados em todos os compartimentos topográficos do carste, de forma padronizada (no total 27 sítios pré-cerâmicos sob abrigo natural foram contemplados). Não restringiam seus movimentos, provavelmente sazonais, apenas a este ambiente como demonstram vestígios 24 encontrados por arqueólogos amadores nas margens do Lago de Furnas (cerca de 80 km a SW do carste). Existem, enfim, indícios circunstanciais para que esses grupos sejam associados à tradição rupestre Planalto. No final argumenta-se pela existência de algumas semelhanças e paralelos com a região de Lagoa Santa, situada 200 km a NE (em linha reta) da região em estudo. / This thesis brings a first archaeological framework for the pre-ceramic occupation of a carstic area situated in the upper São Francisco river valley, also known as the Pains region, with an area of about 1500 km², in the central-western portion of the state of Minas Gerais, Brazil. This was done by the study of seven elements related to these populations: chronology (relative and absolute), technology (lithic and bone), subsistence (faunal remains), burials, mobility, use of space in rock-shelters and rock-art. The most relevant findings were made in excavations and test-pits by artificial levels of 10 cm in four limestone rock-shelter sites, distributed in eleven different places or sectors, all of them from the drip-line to the interior of the shelters, with a total area of 28m². The most important site is the \"Gruta do Marinheiro\" cave, where 20m² were excavated. After the analysis of the different types of materials by level, sector and site, the quantitative and qualitative vertical changes were studied in search for tendencies, ruptures and/or transformations. The horizontal variations between sectors were also observed. These analysis showed that the rock-shelters were intensely occupied in the first three millennia of the Holocene, between ca. 10200 and 7200 years BP, associated with an unifacial and bifacial lithic industry and faunal remains, indicating they hunted small and middle-sized mammals, fished mainly Siluriformes and gathered Gastropoda. They buried their dead in a variety of manners, in patterns that are also seen in other rock-shelters of Minas Gerais associated with the paleo-indian occupation. Looking at 27 known rock-shelters in the region with pre-ceramic evidence, it was also possible to see that they were present in all main topographical areas of this limestone region, indicating a high mobility within it, but also showing some connections with areas outside, as seen by very similar lithic material found by amateurs in the \"Lago de Furnas\" area (80 km to the SW). There is also circumstantial evidence that could relate these groups to the \"Planalto\" rock-art tradition. Finally we argue that there are many elements that put the Pains region close archaeologically to the better-known Lagoa Santa region, situated 200 km to the NE.

As part of Nigeria’s drive to increase electricity production capacity and shift to renewable sources, a new 50 MW photovoltaic (PV) plant is proposed for a town in north-west Nigeria. Rather than using conventional monofacial modules and fixed mounting, it is of interest to consider a selection of new technologies which are attracting growing attention in the global utility PV market. These can increase energy output, and could be used to advantage in this 50 MW plant. However, the technologies, namely bifacial modules and solar tracking, are more expensive than their conventional counterparts, while their relative performance depends on the latitude and climate of the plant location. Thus their economic benefit cannot be taken for granted. The aim of this study is to propose multiple designs for the 50 MW plant using different combinations of module and mounting technologies, finding their economic order of merit by estimating their respective levelised costs of electricity (LCOEs).Using the simulation software PVsyst, the electricity production of different plant layouts and component configurations was estimated. Key parameters such as tilt angle and pitch distance were varied in order to optimise each configuration of technologies. Having sourced economic data from the industry and literature, lifetime plant costs were calculated, which in combination with lifetime electricity production, were used to estimate the LCOE.As expected, results indicated that the optimum configuration was bifacial modules mounted on horizontal single-axis tracking (SAT), followed by monofacial modules on horizontal SAT. Fixed installations had greater LCOEs by a reasonable margin, while the LCOE difference between monofacial and bifacial modules on fixed mounting was within the error of the calculation, meaning this choice relies on more accurate input data. A sensitivity analysis allowed uncertainty in the results to be gauged, and highlighted the factors which most influence LCOE, so that efforts to increase profitability can be focussed in the right places. Finally, suggestions are offered to help optimise bifacial and tracking installations by comparison with conventional plants.The conclusions drawn herein will be specifically relevant to the Swedish developer and EPC contractor Svenska Solenergigruppen which, in due course, will submit a plant design proposal to the project developer of the 50 MW plant. However, it is hoped that this work will act as a guide for any EPC contractor or developer working on a utility PV plant in sub-Saharan Africa, allowing efficient design of an optimal system.

A spatial analysis of the bifacial arrowheads from the Swedish county of Dalarna, located in the inland area of middle Sweden, is presented in this thesis. The study aims to understand how the arrowheads relate to land use and mobility in the landscape. Produced to be mobile and portable, arrows are of sorts synonymous with movement and mobility. Side by side with an exploration of mobility, the activities in the landscape surrounding the arrowheads are investigated with the concept of taskscape. Bifacial arrowheads are found all over Sweden, and in the northern parts they were used most extensively during the Early Metal Age (2000 BC–1 BC). The raw materials used for producing the arrowheads in Dalarna are various local stone materials, but the raw materials have also been spread over long distances, which indicate high mobility or an established contact network. Waterways and ridges in the landscape are suggested as possible communication routes. The bifacial arrowheads are found on different types of dwellings in the landscape, many of them on sites with a mixed chronology. The area by the lake Venjan stands out with its numerous workshop sites, which have a large material of points in red quartzite sandstone, indicating that specialization has taken place. In other parts of Dalarna, the arrowheads are understood as part of a standard toolkit. The study shows the possibilities to analyze archaeological material in the Swedish inland forest areas, which archaeological sites and material needs to be further investigated.

Les industries à pièces bifaciales découvertes en Chine font actuellement l’objet d’interprétations opposées. L’une d’elle, de plus en plus souvent proposée, considère les pièces bifaciales chinoises comme les témoins d’une diffusion à partir de l’Occident. Le modèle traditionnel proposant un isolement technico-culturel de l’Asie de l’Est, matérialisé la « ligne de Movius », serait alors erroné. Ce regroupement des industries à pièces bifaciales chinoises au sein du complexe « acheuléen » ne fait pas l’unanimité et l’hypothèse d’une réinvention locale est également envisagée. Ces hypothèses contradictoires reflètent les lacunes des cadres méthodologiques et conceptuels employés pour l’étude de ces industries. L’approche retenue pour cette étude vise à restituer les intentions placées dans la réalisation de l’outillage par le biais d’une analyse techno-fonctionnelle. Les sites retenus appartiennent à une période comprise entre 1Ma et 500ka : Yangwu, Gaolingpo et Nanbanshan, dans le bassin de Bose (région autonome du Guangxi Zhuang) et les sites de Lantian et Liangshan Longgangsi (province du Shaanxi).Les résultats de l’étude mettent en évidence l’existence de deux traditions techniques distinctes entre le centre le sud de la Chine. Il existe une forte variabilité entre le matériel des deux régions, perceptible par la quasi-absence de schèmes de débitage dans le bassin de Bose et par des différences importantes de composition de l’outillage. Mais surtout, les pièces bifaciales du centre et du sud ne montrent aucune similitude structurelle, technologique ou fonctionnelle. Bien que regroupées sous une même appellation, ces pièces sont des outils différents. Sur un plan diachronique, l’existence en Chine d’industries reposant sur des schèmes de débitage et sur des schèmes de façonnage autour de 2Ma montre la possibilité d’une évolution des lignées techniques à partir d’un substrat technique local. Après 500ka, le phénomène bifacial persiste, mais n’évoluera pas vers des formes plus techniquement investies. Sur un plan spatial, une comparaison avec le matériel bifacial découvert ailleurs en Asie montre que les industries à pièces bifaciales coréennes présentent des similitudes avec les industries chinoises postérieures à 500ka. Par contre, aucun lien n’apparait avec les phénomènes bifaciaux indiens et mongols.Les industries à pièces bifaciales chinoises n’entretiennent pas de lien avec le complexe acheuléen et résultent d’un phénomène de convergence technique. Les phénomènes bifaciaux asiatiques montrent une variabilité temporelle et spatiale bien plus importante qu’habituellement envisagé. / Lately discovered Chinese biface-bearing industries are subject to opposite interpretations. Literature increasingly suggests that Chinese bifaces can be seen as a witness of diffusion from the West. The traditional model, stating a techno-cultural isolation of Asia, embodied in the “Movius Line” would thus be questioned. This assimilation of biface-bearing industries within the “Acheulian complexe” is far from achieving unanimous backing and the hypothesis of a local reinvention is also proposed. These conflicting hypotheses reveal the gaps in the methodological and conceptual frameworks used to study these industries.The chosen approach for this study aims at restoring the goals underlying the production of the tool kit through a techno-functional analysis. Chosen sites belong to a period ranging from 1Ma to 500ka : Yangwu, Gaolingpo and Nanbanshan, located in Bose basin (Guangxi Zhuang), and Lantian and Liangshan Longgangsi sites (Shaanxi province).The outcomes of this contribution bring to light the presence of a well-marked geographical discrimination between the technical traditions observed in the South on one hand and the center of mainland China on the other. A strong variability is underlined between the two areas by the virtual absence of débitage schemes in Bose basin and considerable divergence in the composition of the tool-kits. Significantly, bifacial pieces from the South and the Center show no structural, technological or functional similarities. Even though gathered under one denomination, it is clear that we are dealing with two different kinds of tools. From a diachronic perspective, the existence in China of industries relying on both débitage and shaping schemes around 2Ma indicates the possibility of bifacial technical lineage evolution from a local technical substrate. After 500ka, the bifacial phenomenon still exists but won’t evolve toward more technically invested tools. From a spatial perspective, a comparison with bifacial industries discovered elsewhere in Asia demonstrates that Korean biface-bearing industries bear similarities with Chinese industries after 500 ka. However, Chinese industries don't seem to be linked with Indian and Mongol bifacial phenomena.Chinese bifacial industries show no connexion with the Acheulian complex but rather represent a technical convergence. East-Asia bifacial phenomena involve much stronger variability through time and space than generally considered.

La diversité historique et substantielle de l’Acheuléen d’Europe occidentale est perceptible d’un point de vue phénoménologique. Chacune des 36 séries lithiques de France, d’Angleterre, d’Italie et d’Espagne étudiées dans ce travail présente une production originale. Le phénomène bifacial peut être dissocié des autres manifestations de l’Acheuléen : les pièces bifaciales sensu stricto apparaissent massivement dans le nord de l’Europe autour de l’OIS 11 puis sur le pourtourméditerranéen vers l’OIS 9 mais sous une forme différente, engendrant des modifi cations majeures de toute la production. L’analyse critique des contextes lithostratigraphiques et la prise en compte des diversités technique, technologique ou chronologique des industries permettent de reconsidérer le paradigme de la diffusion « Out of Africa ». Tout conduit à proposer l’hypothèse d’une invention locale de la pièce bifaciale et de son évolution sur place. Le terme a trop longtemps masqué la véritable diversité du Paléolithique inférieur tout entier. C’est vers l’analyse de la pluralité des comportements humains et des sociétés qu’il faut se diriger maintenant. / The historic and substantial diversity of the Western European Acheulian can be perceived from a phenomenological standpoint. All of the 36 lithic assemblages studied in France, England, Italy and Spain provide an original production. The bifacial phenomenon can be separated from other expressions of the Acheulian. Indeed, bifacial pieces, in the strict sense, appear in great numbers in northern Europe around the OIS 11 and in the Mediterranean region around the OIS 9. However, the latter are found under different forms, which imply major modifi cations of all the production. The critical analysis of lithostratigraphic contexts and the consideration of technical, technological and chronological diversities, allow reconsidering the paradigm of the « Out of Africa » diffusion. The hypothesis of a local invention and evolution of bifacial pieces can be put forward. The use of this term has limited our perception of the Lower Paleolithic as a whole. One should now focus on analyzing the diversity of human behaviors and societies.