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Logic Synthesis Techniques for Optical Circuits
No full textIn the past few decades, the semiconductor industry has witnessed rapid progress in semiconductor technology. Devices became smaller and faster thanks to the continuous shrinking of transistor's size. However, with continuous downscaling, the size of the transistor is approaching its physical limits beyond which further scaling will prevent the use of traditional transistor-based technology. As a result, non-transistor computation paradigms are being investigated as alternatives to the traditional technology. Advances in silicon photonics made optical circuits a promising alternative to the traditional technology and unlocked several promising applications for the future. In this thesis, we investigate automatic logic synthesis approaches for optical circuits realizing any given Boolean function. To this end, we propose a variety of synthesis approaches based on different Boolean function representations, in which, optical circuits are synthesized with respect to the technology-specific cost metrics such as the number of gates and the effect of so-called splitter (an optical element which divides a single optical signal into many signals). More precisely, we first propose synthesis approaches based on two-level function descriptions such as Sum-of-Products (SoPs) and Exclusive-Sum-of-Products (ESoPs). Here, optical circuits are synthesized with respect to gate-efficiency (i.e. minimal number of gates) and with respect to splitter freeness. The synthesis guided with respect to gate efficiency and the synthesis guided with respect to splitter freeness reveal that reducing the number of gates and reducing the number of splitters are contradictory optimization objectives. Experimental results also confirm this fact. Next, we consider synthesis of optical circuits based on Binary Decision Diagram (BDD), an efficient data-structure for the representation of large Boolean functions. Although BDDs allow direct mapping of the function representation to an optical circuit (and, hence, a scalable circuit synthesis), they have their shortcomings with respect to the dedicated cost metrics. As a result, we investigate this issue and provide an overview of the BDD-based synthesis schemes which are available thus far. Afterwards, we propose new solutions based on dedicated BDD optimization schemes which aim for addressing the known shortcomings. Experimental results confirm the benefits of the proposed approach. We then propose a synthesis solution based on the AND-Inverter Graphs (AIGs). Herein, mainly two schemes are presented: one approach generates optical circuits with smaller number of gates, thereby yielding significantly smaller circuit sizes and the other one generates optical circuits of smaller splitting effects. Experimental evaluations confirm the benefits of the respective solutions. Lastly, we propose a novel methodology to synthesize optical circuits. To this end, we introduce and exploit OR-Inverter graphs (OIGs) - a data-structure which is particularly suited for the design of optical circuits. Experimental results confirm the efficacy of the OIG structure and the resulting synthesis approach. All the proposed synthesis approaches are compared with each other in terms of the number of gates and the effect of spliiting. Comparisons show that the synthesis scheme relying on AIGs can be a suitable choice when the number of gates is a primary design metric, whereas, synthesis scheme relying on OIGs can be a promising choice when the minimal effect of splitting is desired. Since logic synthesis is the first step towards design automation for optical circuits, therefore, the works presented in this thesis would help the future developments of the corresponding circuit technologies
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Get PDFHigher Education in Switzerland: Predictors of Becoming Engaged in Higher Vocational or Academic Education - the Role of Workplace Factors
Get PDFContext: Enthusiasm has been noted to increase productivity and quality at work. In teachers' work, this has a connection to student learning and motivation, as well as teaching quality. In the context of Finnish vocational education and training (VET), research on enthusiasm appears especially topical and relevant because of the ongoing wide reform with emphasis on productivity and efficiency. Approach: In this study, Finnish VET teachers' enthusiasm at work was studied qualitatively. Three research questions were set for this study: (1) How do VET teachers describe their enthusiasm?; (2) What factors strengthen their enthusiasm, according to their descriptions?; and (3) What factors weaken their enthusiasm, according to their descriptions? Altogether, 103 teachers who voluntarily participated in the study completed an online questionnaire on enthusiasm. The data were analyzed through qualitative content analysis. Findings: According to the results, the teachers who participated in the study were very interested in their work. They wanted to share how they experienced enthusiasm in their work. Their enthusiasm manifested as their willingness to develop their skills and expertise. It also showed in their dedication, good job performance, and positive feelings about their work. Student encounters, a positive atmosphere, and work interactions were the main sources of enthusiasm. Lack of resources, changes, cuts in the VET budget, and a lousy work atmosphere weakened enthusiasm. Conclusion: The study found that enthusiasm manifested itself in ways that correspond well with the current VET productivity and efficiency goals. Because enthusiasm was strengthened especially when teachers were working with students, it seems important to ensure a supportive work environment for students also after the VET reform. Positive interactions, collegial support, and working together can help teachers to succeed and to maintain enthusiasm in their everyday work. According to the results of this study, supervisors may play a central role in facilitating teacher enthusiasm
Interview with Avinash Kumar, Creative Director & Co-Founder, Quicksand Design Studio
Get PDFInterview with Avinash Kumar, Creative Director & Co-Founder, Quicksand Design Studio, India
Interview With Ben Joseph P. Banta, Founder Of Ranida Games
No full textInterview With Ben Joseph P. Banta, Founder Of Ranida Game
Perilous and Peril-Less Gaming : Representations of Death with Nintendo s Wolf Link Amiibo
Get PDFThis article examines the motif of death in popular electronic games and its imaginative applications when employing the Wolf Link Amiibo in The Legend of Zelda: Breath of the Wild (2017). As I demonstrate, the Wolf Link Amiibo engages digital quietus as a meaningful event in three ways: as in-game perk, as ritualized object, and as narrative device. In the first place, the toy-to-life figurine mitigates against recursive elimination by generating an NPC (non-player character) to hunt for food, search out hidden shrines, and attack nearby enemies. Second, it affords a unique awareness of death according to a temporal pattern, one that requires ritual performance outside the virtual world of Hyrule. Third, the small statue conceptually narrativizes the repeated loss of life through an aesthetic of resurrection, namely by representing the Amiibo as efficacious technology found within the game-world of Breath of the Wild
Death, Fabulation, and Virtual Reality Gaming
Get PDFThere are few things more common in video gaming than death. The result of falling, stabbing, shooting, draining, and countless other verbs of decay and destruction. Talk of dying in video games often exchanges teleological weight for the more pragmatic machinic signaling of transition back to the actual world from a gamic one. In the relatively short history of the video game medium, there is little evidence that a video game death might trigger any existential self-reflection. This paper argues that contemporary virtual reality technology can change video gaming s relationship to death through its ability to trigger out-of-body experiences. To make this case, I examine the VR games Arizona Sunshine and Deep Sea in light of scientific studies exploring the affective and ideational influence of VR experiences. I then reframe them in light of the virtual philosophy of Henri Bergson, specifically his theorization of fabulation as the religious tendency of the human body, exposing VR s ability to take advantage of various capacities of human embodiment, which amplify the visual and tactile affordances of the video game medium. In doing so, this paper raises the ever-present concerns and questions of all new technology and media as they shape how we think about ourselves in relation to death, embodiment and subjectivity
Investigating sedimentary records of deglacial outburst events from the Laurentian Channel Ice Stream
No full textSediments derived from the eastern Canadian Continental Margin preserved the whole records of deglacial meltwater discharges since the Wisconsinan when the entire margin was glaciated by the Laurentide Ice Sheet. Large volume of meltwater or iceberg release were created when the ice sheet began to landward shrink and retreat. Such discharges and calving events caused erosion of the bedrocks and delivered the terrestrial sediments to the adjoining shelf and fan system. Ice streams are believed to play a major role of Ice sheet movement. The Laurentian Channel Ice Stream (LCIS) and numerous canyons on the slopes are the main pathway for the sub-glacial meltwater discharge from Gulf of St. Lawrence. Thick reddish mud event layers deposited on the Laurentian Fan have been recognized as representing deposits of the major meltwater discharges between Heinrich Event 2 and 1. Those reddish sediments were sourced from Permo-Carboniferous redbeds and created by subglacial outburst floods events. However, the event chronology and scenarios are lacking understanding, the compositions and provenance of the event beds are still unknown and the correlation to the Laurentide Ice Sheet retreat history is also unclear. In the framework of this thesis, I investigate three new sediment cores (GeoB18514-2, 18515-1 and 18516-2) retrieved from the southwestern Grand Banks slope and stratigraphically link these cores to eastern Laurentian Fan core MD95-2029, further to the Scotia Margin cores 99036-008, 99036-028 and 99036-057. In addition, 80 estuarine and coastal reference samples among the Gulf of St. Lawrence area and Newfoundland were collected to represent all major source rock lithologies. High-resolution granulometric, rock magnetic, radiographic, colorimetric core logs and radiocarbon dates as well as the geochemical properties (major elements, trace elements) were produced for the cores. Subsequently the properties of the event beds samples are compared with the reference samples from the potential source areas. Such interdisciplinary approaches allow us to better understand the red mud event beds story
A novel mechanism for the anaerobic degradation of non-methane hydrocarbons in archaea
Get PDFCrude oil and natural gas are formed due to the degradation of the organic matter in deep subsurface layers. From there, they can migrate towards the sediment surface, where they represent an energy source for microbial communities. Anaerobic methanotrophic archaea (ANME) are the main responsible of anaerobic oxidation of methane in anoxic environments. For methane oxidation, they use a reversal of the methanogenesis, whose key enzyme is the methyl-coenzyme M reductase (MCR). However, little is known about the role of archaea in the anaerobic oxidation of other hydrocarbons. Apart from ANME, only three archaea are described as anaerobic hydrocarbons degraders, although the three use mechanisms of bacterial origin. The aim of my thesis is to shed light on the role of archaea in anaerobic hydrocarbon degradation. In Chapter II, we describe a new pathway to degrade butane and propane in two archaeal strains of the newly described clade Candidatus Syntrophoarchaeum, which we cultivated in consortia with syntrophic partner bacteria. Using meta-omics approaches, we discovered that Ca. Syntrophoarchaeum use before uncharacterized divergent MCRs to activate butane and propane. The produced alkyl-CoM units are then fully oxidized using a combination of different pathways and the reducing equivalents are transferred to the partner bacteria for sulfate reduction. Chapter III reports about archaea harbouring similar mcr genes in oil seeps of the Gulf of Mexico. Archaea of the D-C06 clade were especially abundant in these environments and we could visualize them in oil droplets without any associated bacteria. Metagenomic analyses revealed that D-C06 had a machinery for alkane degradation similar to Ca. Syntrophoarchaeum, including a divergent mcr gene. Strikingly they also contained a complete methanogenesis pathway with a canonical mcr copy. Therefore, we hypothesize that D-C06 are degrading hydrocarbons coupled to methane production in a single cell. Chapter IV focuses on the physiology of Ca. Syntrophoarchaeum using different substrate incubations, temperature growth studies and transcriptomics. Growth was detected only on butane and propane. While two Ca. Syntrophoarchaeum strains were found in butane enrichments, only one was detected in the propane cultures. Analysis of the expression of mcr genes revealed certain links between substrates and MCR enzymes. The knowledge for culturing these anaerobic hydrocarbondegrading organisms is summarized in a detailed protocol in Chapter V, which may help in the cultivation of similar archaeal clades in the future. In summary, my thesis describes a novel pathway in archaea to degrade hydrocarbons anaerobically. The key element is highly divergent MCRs that are capable to activate multi-carbon alkanes. This constitutes a genuine archaeal mechanism, previously unknown. Genomic analyses have revealed that this pathway can be found in different archaeal clades like Ca. Syntrophoarchaeum or DC06 with different lifestyles. These archaea are detected in diverse hydrocarbon-rich environments like oil and gas seeps and deep reservoirs. This indicates a so far unexplored role of these groups in hydrocarbon degradation that should be addressed in future research
Dry deep drawing of a rectangular cup assisted by volatile media injected from laser-drilled microholes
Get PDFTechnical, economic and legal requirements lead to increasing demands on lubricants in sheet metal forming. Moreover, the effects of lubricant application on the environment become more and more relevant. The long-term goal in sheet metal forming is to reduce the amount of lubricant used in order to conduct sheet metal processing without lubricants in future. Based on the efforts of dry forming, a new procedure for the lubrication of deep drawing processes with volatile media as lubricant substitution is being developed at the University of Stuttgart. This method enables the insertion of an intermediate medium under high pressure through laser-drilled microholes into the tribological system without subsequent, cost-intensive cleaning processes as the volatile media evaporate without residue when the pressure is reduced to ambient pressure. During the first and second funding period of this research project, a general applicability of volatile media as lubricant substitutes was demonstrated by means of strip drawing experiments and a simple academic test component of an Ushaped profile. For this purpose, several problems in the area of fluid supply to the tool were solved. In this report, new findings from investigations of the pressure state of volatile media in the tool contact zone, depending on number, nozzle type and arrangement of laser-drilled microholes, are presented. In addition, results of the optimized laser drilling process are included. These investigations serve as a base for the new, more realistic implementation of the new approach of dry forming in a deep drawing tool. The design of this tool for the deep drawing of a rectangular cup is presented here in detail. Initial investigations of the deep drawing process have also shown that volatile lubricants can be used to realize a significantly enlarged process window compared to conventional lubricants. This promising result shows the wide range of applications for the new tribological system in deep drawing processes