Abstract This thesis explores the integration of work practice and system design in deliberating upon how to increase the sensitivity of system design towards everyday work practice. The attempt to make work practice visible and intelligible for system design necessarily relates to two very different bodies of knowledge: the actual work activities and knowledge of practitioners, and what is considered relevant information for requirements analysis in system design. The strategy of this work comprises the integration of ethnographically informed study of work practice and participatory design by drawing on the longitudinal fieldwork of studying technologically mediated radiology work and promoting work practice based participatory design interventions into technology projects in the clinic of radiology. The adopted theoretical attitude of interweaving construction and reconstruction necessitates questioning and reconfiguring some of the taken-for-granted assumptions of disciplinary dichotomies and conventional frames of reference both with regard to ethnographic traditions focused on current practices as well as technology-centered and future-oriented system design. Radiology, with its ongoing and complex transition from film-based to digitally mediated work, has provided the concrete setting for thinking about the relations between researcher, designer and work practice practitioner in an attempt to find ways in which to sensitise system design towards everyday work practice. Establishing the relevance between ethnographic findings of work and design specifications requires a reformulation of work practice that appreciates the everyday fluency of work practice and recognises the endogenous change for the needs of system design. The possibilities of extending the multivoiced expertise prevalent in participatory design with an explicit interest on emic-etic views and knowledges inherent within ethnographic traditions is explored through reflecting on the changing researcher knowledge and location. The reflections are also used in developing a tool for work practice oriented participatory design and in constructing the role of participant interventionist. Through mutual exploration and constructive collaboration of ethnographic and participatory design traditions as well as scrutiny of actual design sessions, the dimensions of analytic distance, horizon of work practice transformations and situated generalisation are put forward as general interactions of work practice sensitive participatory design.

Ce travail porte sur l'étude du comportement mécanique d'une console courte en béton armé renforcée par collage de tissus en fibres de carbone et en particulier sur l'influence du nombre de couches de tissus en fibres de carbone, du type du renforcement, de l'orientation des tissus composites, du type de tissus en fibres de carbone. Les résultats montrent que la performance de la console n‘augmente pas linéairement en fonction de l'épaisseur de la plaque composite. Il existe une épaisseur optimale de tissus en fibres de carbone. Dans le cas du renforcement sur les deux faces du béton, il existe un nombre de couches optimales. Dans le cas du renforcement par bandage, l'épaisseur de matériaux composites plus intéressants est de trois couches. Par contre, la résistance de la console renforcée dépend fortement de la surface renforcée. Les résultats montrent également que le comportement d'une console renforcée peut être présenté en trois phases: la phase élastique globale, la phase de la propagation de fissures et la phase de l'ouverture des fissures diagonales. Le renforcement de la console permet d'augmenter considérablement la résistance ultime de 20 à 82% et la rigidité de la console. Les ruptures des consoles renforcées peuvent être résumées en cinq modes. En se basant sur les résultats obtenus et les modèles existants, la résistance ultime de la console renforcée et non renforcée a été estimée et analysée. Un modèle basant sur lа théorie de l'endommagement a été développé dans ce travail. L'effet de fatigue sur le comportement et sur la résistance ultime de la console courte renforcée a été également étudié dans ce travail. / This study deals with mechanical behaviour of strengthening reinforced concrete corbel by bonding carbon fibre sheet and in particular the influence of the number of layers of carbon fiber fabric, the type of strengthening, the orientation of the composite fabric and the type of carbon fiber fabrics .The results show that the performance of the corbel does not increase linearly with the thickness of the composite plate. There is an optimum thickness of the carbon fiber fabrics. In the case of strengthening on both sides of the concrete, there are an optimum number of layers. In the case of fully wrapped strengthening, the most interesting thickness of the composite is three layers. However, the resistance of the strengthening reinforced concrete corbel depends strongly on the bonded surface.The results also show that the behavior of strengthening corbel can be presented in three phases: the overall elastic phase, the phase of crack propagation and the phase of the opening of diagonal cracks. Strengthening the corbel can significantly increase the ultimate strength from 20% to 82 % and the stiffness of the corbel. The failure of the strengthening corbel can be summarized in five modes.Based on the results obtained and the existing models, the ultimate strength of the strengthening corbel or without strengthening, was estimated and analyzed. A model based on damage theory has been developed in this work. The effect of fatigue on the behavior and ultimate strength of the reinforced concrete corbel has also been studied.

Historically there has been many changes to the construction of fatherhood. These changes have not been linear and most significant changes took place during the twentieth century. Four ways of being and acting as a father (i.e., Discourses) have been identified: the father as moral overseer; the father as distant breadwinner; the father as sex-role model, and the new nurturant father. Previous studies have indicated that men’s experiences of fatherhood are very diverse and multifaceted. Fathers may experience intense feelings of elation and happiness, as well as depression and anxiety. Results even indicated that some fathers experienced physical symptoms such as morning sickness or hormonal changes, similar to what the mother could experience. There is also a distinction between three phases: pre-natal, the birth, and post-natal. However, there is a significant gap in the available knowledge related to the subjective experience of fathers, particularly in the South African context. This study is an exploration from within a social constructionist framework, of the experiences of first-time fatherhood. Using a multiple-case study design, the aim was to explore and answer the question: “How do men experience first-time fatherhood?” A qualitative approach to research was applied and three first-time fathers were recruited applying purposive and snowball sampling strategies for interviews that were conducted during May to June 2003. The Zaltman Metaphor Elicitation Technique, which requires the participants to build a collage and participate in a semi-structured interview, was utilized for data collection. Data were analysed by way of thematic analysis, based on transcriptions and translations of the interview material. Three major themes emerged from the data: responsibility, feelings and thoughts and relationships. Collectively, ten sub-themes were extracted from the interviews.. With regard to responsibility, the three first-time fathers indicated that they associated aspects such as financial, emotional and educational provision as primary concerns of first-time fatherhood. Thoughts and feelings ranged from feelings of happiness and elation, stress and anxiety, to confusion and helplessness, as well as a sense of a loss of freedom. In terms of relationships, family, marriage, and the father-child relationship, emerged as significant in their overall experience of first-time fatherhood. These themes and the sub-themes were identified in both the collage and interview material collected for each father. The utilisation of the ZMET and a qualitative approach based in a social constructionist perspective proved useful in eliciting the more intimate experiences of first-time fatherhood. The project was, however, limited because only white male subjects were involved, and themes related to masculine stereotypes in the construction of the father’s reality of first-time fatherhood, and the gender of the baby, could not be explored. Further research on the topic is therefore proposed to explore the richness of the topic and to offer context-specific constructions of the multiple realities of first-time fatherhood. / Dissertation (MA (Research Psychology))--University of Pretoria, 2006. / Psychology / unrestricted

Cette thèse s’inscrit dans le contexte de l’ANR ISABEAU (Innovating for Structural Adhesive Bonding Evaluation and Analysis with Ultrasounds, associant des physico-chimistes et des acousticiens) et cherche à apporter des connaissances nouvelles sur l’évaluation par ultrasons du niveau d’adhésion d’un collage structural par ondes de Lamb. La première partie porte sur l’aspect cohésif et particulièrement sur l’influence du paramètre de réticulation de réseaux époxys sur les courbes de dispersion des ondes de Lamb. La deuxième partie est consacrée à la caractérisation de niveaux d’adhésion dans une structure bicouche Aluminium Epoxy en tenant compte aussi bien des aspects cohésifs qu’adhésifs. Des échantillons à niveau d’adhésion connus et maîtrisés sont réalisés avec l’aide de physico-chimistes, où l’époxy est partiellement ou totalement réticulé, et où l’interface substrat adhésif a subit différents traitements chimiques et/ou mécaniques. Les résultats expérimentaux sont confrontés à ceux issus du modèle rhéologique de Jones résolu par éléments finis. Enfin, la troisième partie porte sur l’étude d’un assemblage tricouche Aluminium/Epoxy/Aluminium et cherche à qualifier différents niveaux d’adhésion à l’aide du modèle de Jones par ondes guidées et également par l’étude des fréquences de coupure des modes verticaux de la structure. / This thesis is in the context of the ANR ISABEAU (Innovating for Structural Adhesive Bonding Evaluation and Analysis with Ultrasounds, with the association of physico-chemists and acousticians) and seeks to bring new knowledge of the ultrasonic evaluation of the level of adhesion of structural bonding using Lamb waves. The first part focuses on the cohesive aspect, in particular on the influence of the crosslinking parameter of the polymer on the Lamb waves dispersion curves. The second part is dedicated to the evaluation of the adhesion level of a bi-layer Aluminum Epoxy taking into account the both cohesive and adhesive aspects. Samples of controlled and known adhesion levels are manufactured with the help of physico-chemists, where the crosslinking of the epoxy is partial or total, and the interface substrate-adhesive have been treated chemically and/or mechanically. The experimental results are compared to those obtained from a predictive model based on the rheological model of Jones solved by finite elements method. Finally, the third part focuses on the study of tri-layers Aluminum/Epoxy/Aluminum, looking for the qualification of different levels of adhesion with the Jones model using guided waves as well as the cut-off frequencies of the structure.

This study focuses on Berni Searle’s art, in which she searches for alternative figurations of identity. For Searle, identity as a category seems insufficient, as it cannot account for individuals of mixed heritage. Searle’s body of work testifies to an attempt to position and locate herself and marginalised subjects within post-apartheid South Africa. History, tradition, culture, race and gender are pivotal to Searle’s visual examination of her body and her identity, as these inscribe the subject at both symbolic and physical levels. Identity was investigated within South African context and the contexts of various postcolonial, postmodern and feminist debates. Searle’s works were investigated revealing nomadic subjectivity, as philosophised about by Gilles Deleuze and theorised about by Rosi Braidotti. Nomadic subjectivity promotes the notion that identity is fluid and located in the interstitial spaces between dichotomies and various debates. The habitation of such liminal spaces in the interstices between binary oppositions and views relates to what Homi Bhabha has defined as the “third space” and the notion of hybridity. Searle constructs her identity by affixing disparate aspects of her self. This is a continuous process whereby the artist inserts and erases her body. Searle’s works are investigated by using the film as a format. In Cinema 1: the movement-image (1986) Deleuze outlined three core cinematic elements, namely the frame, shot and montage, which are employed in an attempt to investigate the various processes at work in Searle’s artistic production. In addition to this, these filmic components were considered for their conceptual implications both in terms of the medium of film and symbolically. The concept of time, as discussed in Cinema 2: the time-image (1989) was utilised to investigate the implications of time for the nomadic subject and the notion of memory. Copyright 2005, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. Please cite as follows: Adendorff, A 2005, Nomadic figurations of identity on the work of Berni Searle, MA dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-12072005-161121 / > / Dissertation (M (Visual Studies))--University of Pretoria, 2006. / Visual Arts / unrestricted

This thesis describes the artwork of Max Bucaille (1906-1996), an obscure French artist who, as a professor of mathematics, had become famous mainly for his surrealistic collages. I am aiming to clarify the relationship of Bucaille to the Czech environment and the Czech artists. I am also focusing mainly on his imprisonment during WWII in prison camp Stalag IV C located in current Czech Republic; his activity in a group of Revolutionary Surrealists between 1947 and 1948, which also included members of Czech Group Ra; and his exhibitions in Czechoslovakia in the 1960's. His work had been introduced to our country thanks to the affiliation of Brno based surrealist group Lacoste along with the international group C.I.A.F.M.A. (Centre international d'actualité fantastique et magique) which was founded in 1958 in Brussels, Bucaille was also among the founders of this group. Considering the focus of this work it is also necessary to mention and to outline the situation of post war surrealism in the Czech countries. There are also comments regarding post war searches for Czech artists which were halted by the political event of February 1948, which completely ended free artwork as well as foreign connections. Then there is a description of the liberalization that happened toward the end of the 1950's...

Last summer, when I began thinking about my thesis, I tried to look back on my earlier work with a more critical eye. I noticed that my focus had largely been on trying to find my own idiom, and improving my construction skills. In the middle of my education I discovered the freedom in draping, and I challenged myself by putting the pen aside and instead make three-dimensional sketches. Looking back, I believe that I succeeded in producing the organic expression I had envisioned. I had still to explore materials more deeply, though, and therefore I made a summer course with exclusive focus on materials. These were the first steps towards beginning my thesis. There were a lot of things I wanted to explore in my thesis, and many techniques I wanted to try. I wanted to believe in myself and my strong sides, but also dare to explore completely new things and go one step further than before, without fear- ing failure. Being very comfortable with construction and cutting, I can quickly try my ideas to see if they work out or not. My sketching is uncontrolled, coarse and pretty abstract, it is through sketching my ideas evolve. I am fast when I make my sketches, be it by pen or three-dimensionally, but I work much more slowly towards the end when it’s time to work on the details, where I am meticulous.

Under 2018–20 har jag under min masterutbildning i komposition inkluderat mina egna erfarenheter av synestesi och associerad synestesi i komponerandet och här även försökt att beskriva mina metoder för detta. Jag har försökt överföra upplevelser av text, färg, form och rörelse till musik. Detta är delvis inspirerat av pedagogen Gertrud Grunows arbete på Bauhaus för 100 år sedan men även av mina tidigare arbeten med kollage, grafiska partitur och dans. De ensembler jag skrivit för har varit mycket varierade idiomatiskt och storleksmässigt. För mig som komponist, sångare och improvisatör, men också pedagog är de synestetiska (associativa eller konkreta) metoderna en för mig oändlig källa till inspiration och ett praktiskt sätt att närma sig det kreativa arbetet. Min roll som utövande improvisationsmusiker är också en del av det, då improvisationen aktiverar så många delar av sinnet. Visuell, auditiv, kinestetisk och taktil inlärning påverkar hur vi förnimmer världen. Om du förstår individens unika perception får du större medkänsla och dessutom ett mindre prestationsladdat förhållande till ditt eget skapande. Det bild- eller textmaterial jag skapar hjälper mej att minnas mina grundidéer. Syftet med att vandra mellan olika medium, idiom och förnimmelser är att hitta ett sätt att komma kreativiteten nära – i smyg. / During the years 2018–20 I have included my own experiences of synesthesia and associated synesthesia in my composition processes, and in this essay I am describing the methods I have been using. I have tried to transform experiences of words, color, texture, form, and movement to music. This is, to some extent, inspired by the work of the pedagogue Gertrud Grunow at the Bauhaus art school in Germany 100 years ago, but also by my own earlier works with collages, graphic scores and dance. The ensembles I have been writing for have been varied idiomatically and in size. To me, as a composer, singer and improviser, but also as a pedagogue, synesthetic methods (both associative or concrete) are an endless source of inspiration and a practical way to approach the creative work. My role as a performing, improvising musician also takes a part of it since the improvisation activates so many different sections of the sensory system. Our different ways of learning, through the visual, audiative, kinesthetic and tactile, affect how we perceive the world. If you can learn to recognize different modes of individual perception, you will get a greater respect for your fellow humans, and also diminish the performance anxiety you might have in relation to the creativity. The texts and visual material I create in my processes help me to remember the original sources of inspiration. The purpose of wandering in between different media, idioms and sensations is to find practical ways to stealthily approach creativity. / <p>"From Ash to Birch" Lina Nyberg, KMH Symphony Orchestra, conducted by Simon Bång</p><p></p>

De nombreux paramètres interviennent dans la longévité des inlays/onlays réalisés par CFAO tels que l’usinabilité et les propriétés mécaniques des matériaux utilisés, l’adaptation de la restauration ainsi que la qualité de l’interface entre le matériau de restauration en céramique ou en composite et le matériau d’assemblage. Dans un premier temps, au travers d’une revue systématique de la littérature, nous avons sélectionné les méthodes expérimentales et les paramètres permettant d’évaluer l’adaptation de ces restaurations. Il existe des techniques en 2D qui mesurent l’espace dent-matériau à des points de référence présélectionnées et des techniques en 3D (Triple-scan, micro-CT) qui mesurent l'ensemble de l'interface. Cette revue de la littérature nous a permis de mettre en évidence que : le matériau de restauration, le type de préparation, le vieillissement, le collage ou non de la restauration et des paramètres propres à la CFAO ont une influence sur l’adaptation. Dans un deuxième temps, nous avons étudié les propriétés mécaniques de blocs en céramique et en composite et l’adaptation interne in vitro d’inlays usinés à partir de ces mêmes matériaux. L’influence de la nature du matériau de restauration et de son usinabilité sur l’adaptation a été mise en évidence. La troisième partie de notre travail a porté sur la qualité de cette interface par un test de résistance en microtraction et une analyse du type de fracture. Une relation étroite a été démontrée entre la microstructure du bloc testé et le type de traitement de surface utilisé. Ce travail a souligné l’importance d’utiliser plusieurs méthodologies et de les croiser entre elles afin de mieux corréler nos résultats. L’étude du vieillissement de ce joint dento-prothétique constitue un travail à part entière dans laquelle certaines méthodologies utilisées dans cette thèse (profils de rupture, essais mécaniques) peuvent être transposées / Several parameters are involved in the longevity of CAD-CAM inlays/onlays restorations such as the machinability and mechanical properties of the materials used, the adaptation of the restoration and the quality of the resin cement-ceramic or composite interface. Initially, through a systematic review of the literature, the experimental methodologies and parameters to evaluate the adaptation of these restorations were selected. The gap between the tooth and the material, at preselected reference points, is measured by 2D techniques. 3D techniques (Triple-scan, micro-CT) are able to measure the entire interface. This review of the literature allowed us to highlight that: the restorative material, the preparation design, aging, the use of a bonding-system and parameters regarding the CAD-CAM technology have an influence on the marginal adaptation. Afterwards, we assessed the mechanical properties of CAD-CAM ceramic and composite blocks and the internal adaptation in vitro of inlays milled with these same materials. The influence of the nature of the restorative material and its machinability on adaptation was put forward. The third part of our work focused on the quality of this interface using a microtensile bond strength test and a fracture type analysis. A tight association has been shown between the microstructure of the tested blocks and the type of surface treatment applied. This work underlined the importance of using several methodologies and crossing them to better correlate our results. Studying the aging of this dento-prosthetic joint constitutes a whole work in which some approaches used in this thesis (fracture profiles, mechanical tests) can be implemented and transposed

Des rendements record à plus de 26% ont récemment été démontrés avec des cellules solaires en Si, approchant la limite théorique de 30% pour une seule jonction. Les cellules solaires à multi-jonctions (MJSC) fabriquées à base de matériaux III-V peuvent dépasser cette limite: des rendements supérieurs à 45% ont été reportés pour une cellule à 5 jonctions sous un soleil et pour une cellule à 4 jonctions sous lumière concentrée. Cependant, pour des applications terrestres, le coût élevé de ces technologies impose l’utilisation d’une haute concentration, ce qui augmente la complexité du système.Une solution intermédiaire consiste à fabriquer des cellules solaires III-V à haut rendement sur des substrats Si, moins coûteux que les substrats III-V ou Ge utilisés dans les MJSC classiques. Des rendements supérieurs à 33% ont déjà été démontrés pour des MJSC fabriquées par collage direct. Ceci, combiné aux progrès récents dans la réutilisation des substrats III-V, présage un avenir prometteur pour les cellules solaires tandem III-V sur Si, ce qui pourrait mener à la prochaine génération de systèmes photovoltaïques à haut rendement et faible coût.Dans ce travail de thèse, des cellules solaires tandem AlGaAs//Si à 2 jonctions (2J) et GaInP/AlGaAs//Si à 3 jonctions (3J) ont été fabriquées par collage direct, ce qui a donné lieu à une configuration à 2 terminaux (2T).Différentes techniques de collage ont été étudiées, notamment une approche innovante présentant un potentiel d'industrialisation prometteur pour l’intégration des matériaux III-V sur Si. Les propriétés électriques de l'interface de collage GaAs//Si ont été analysées à l'aide de dispositifs de test dédiés conçus au CEA, permettant d'évaluer la résistance d'interface et le mécanisme de conduction.Des caractérisations et simulations expérimentales ont été effectuées afin d'optimiser le design et le processus de fabrication, conduisant à des rendements record. Pour la sous-cellule supérieure en AlGaAs de la 2J, cela comprend l'utilisation d'une fenêtre en AlInP avec un émetteur en GaInP, formant une hétérojonction n-GaInP/p-AlGaAs, qui améliore les performances pour les faibles longueurs d'onde. De plus, la réduction de l'épaisseur de la couche de collage en GaAs et l'utilisation d'une jonction tunnel en AlGaAs, avec bande interdite plus large, augmentent la transparence et donc le photocourant de la sous-cellule inférieure.Pour la sous-cellule inférieure en Si, les simulations ont permis d'identifier les facteurs clés qui limitent les performances, la durée de vie étant la caractéristique la plus critique dans les cellules Si épaisses utilisées. Dans le cas des interfaces III-V//Si, un émetteur fortement dopé est essentiel pour minimiser la recombinaison de surface et donc augmenter la tension en circuit ouvert. La passivation de la surface arrière est également importante, notamment pour augmenter la réponse dans l’infrarouge. Différents processus de diffusion et d'implantation ont été étudiés pour former l'émetteur. Les processus d'implantation ont montré moins de dégradation de la durée de vie et des surfaces moins rugueux, permettant ainsi le collage sans planarisation chimico-mécanique et donc des niveaux de dopage plus élevés en surface.Finalement, afin d’évaluer correctement le rendement de conversion de ces cellules tandem III-V sur Si, une méthode de caractérisation courant-tension rapide et peu coûteuse, adaptée aux MJSC sous faible concentration a été développée. Cette méthode ne nécessite pas de cellules isotypes parfaitement identiques, à la place, des cellules Si à simple jonction avec filtres optiques sont utilisées. Une efficacité de 23,7% sous 10 soleils a été démontrée de cette manière pour la cellule AlGaAs//Si, qui est le rendement le plus élevé signalé à ce jour pour une cellule tandem à base de Si avec 2J et 2T. / Si solar cells with record efficiencies over 26% have been recently demonstrated, approaching the Si single-junction limit of 30%. Multi-junction solar cells (MJSC) based on III-V materials can overcome this limit: efficiencies over 45% have been reported for a 5-junction under 1 sun and for a 4-junction under a concentrated illumination of 300 suns. Due to their elevated cost, these cells could be used in terrestrial applications only if operated under very high sunlight concentration for commercial terrestrial applications, which in turn increases the module and system complexity.An intermediate solution consists in fabricating high efficiency III-V solar cells on Si substrates, which are less expensive than the III-V or Ge substrates used in conventional MJSC. Mechanical-stacked and wafer-bonded solar cells, which avoid the unresolved issues of III-V on Si epitaxy, have already demonstrated efficiencies over 33%. This, combined with the recent advancements in the field of substrate reuse, predict a promising future for III-V on Si tandem solar cells, which could lead the next generation of high-efficiency and low-cost photovoltaics.In this PhD work, 2-junction (2J) AlGaAs//Si and 3-junction (3J) GaInP/AlGaAs//Si tandem solar cells were fabricated. The Si bottom subcell and the III-V top subcell(s) were joined together by wafer bonding, resulting in a 2-terminal (2T) III-V//Si solar cell configuration.Different wafer bonding techniques were studied, including an innovative bonding approach showing promising industrialization potential and thus, opening a new path for III-V on Si processing. The GaAs//Si bonding interface electrical properties were analyzed using dedicated test devices originally conceived at CEA, allowing to evaluate the interface resistance and the conduction mechanism.Experimental characterizations and simulations were performed in order to optimize the design and fabrication process, leading to record efficiencies. For the AlGaAs top subcell of the 2J, this includes the use of an AlInP window together with a GaInP emitter, forming an n-GaInP/p-AlGaAs heterojunction, which improved the short wavelength performance. In addition, the reduction of the GaAs bonding layer thickness and the use of a higher bandgap AlGaAs tunnel junction resulted in a higher transparency and a bottom subcell photocurrent improvement.For the Si bottom subcell, simulations allowed to identify the key factors that limit the performance, being the bulk lifetime the most critical characteristic in the thick Si cells used. In the case of III-V//Si interfaces, a highly doped emitter is crucial to minimize the surface recombination and maximize the open-circuit voltage, outweighing the drop in short-circuit current due to lifetime degradation. Back surface passivation is also important, specially to increase the infrared response. Different diffusion and implantation processes for the emitter formation were studied. Implantation processes showed less bulk lifetime degradation and smoother surfaces, thereby allowing bonding without chemical-mechanical planarization and thus higher doping levels at the surface.Finally, in order to correctly assess the efficiency of these III-V on Si tandem cells, a fast and low-cost current-voltage characterization method adapted for MJSC under low concentration was developed. This method does not require perfectly matched component cells and instead, Si single-junction cells with optical filters are used as pseudo-isotypes. An efficiency of 23.7% under 10 suns was demonstrated this way for the AlGaAs//Si cell, which is the highest efficiency reported to date for a 2J 2T Si-based tandem cell.