Quantum-dot Cellular Automata: Review Paper

Quantum-dot Cellular Automata (QCA) is one of the most important discoveries that will be the successful alternative for CMOS technology in the near future. An important feature of this technique, which has attracted the attention of many researchers, is that it is characterized by its low energy consumption, high speed and small size compared with CMOS.  Inverter and majority gate are the basic building blocks for QCA circuits where it can design the most logical circuit using these gates with help of QCA wire. Due to the lack of availability of review papers, this paper will be a destination for many people who are interested in the QCA field and to know how it works and why it had taken lots of attention recentl

Logic Synthesis for Established and Emerging Computing

Logic synthesis is an enabling technology to realize integrated computing systems, and it entails solving computationally intractable problems through a plurality of heuristic techniques. A recent push toward further formalization of synthesis problems has shown to be very useful toward both attempting to solve some logic problems exactly--which is computationally possible for instances of limited size today--as well as creating new and more powerful heuristics based on problem decomposition. Moreover, technological advances including nanodevices, optical computing, and quantum and quantum cellular computing require new and specific synthesis flows to assess feasibility and scalability. This review highlights recent progress in logic synthesis and optimization, describing models, data structures, and algorithms, with specific emphasis on both design quality and emerging technologies. Example applications and results of novel techniques to established and emerging technologies are reported

THEORY, DESIGN, AND SIMULATION OF LINA: A PATH FORWARD FOR QCA-TYPE NANOELECTRONICS

The past 50 years have seen exponential advances in digital integrated circuit technologies which has facilitated an explosion of uses and functionality. Although this rate (generally referred to as "Moore's Law") cannot be sustained indefinitely, significant advances will remain possible even after current technologies reach fundamental limits. However if these further advances are to be realized, nanoelectronics designs must be developed that provide significant improvements over, the currently-utilized, complementary metal-oxide semiconductor (CMOS) transistor based integrated circuits. One promising nanoelectronics paradigm to fulfill this function is Quantum-dot Cellular Automata (QCA). QCA provides the possibility of THz switching, molecular scaling, and provides particular applicability for advanced logical constructs such as reversible logic and systolic arrays within the paradigm. These attributes make QCA an exciting prospect; however, current fabrication technology does not exist which allows for the fabrication of reliable electronic QCA circuits which operate at room-temperature. Furthermore, a plausible path to fabrication of circuitry on the very large scale integration (VLSI) level with QCA does not currently exist. This has caused doubts to the viability of the paradigm and questions to its future as a suitable nanoelectronic replacement to CMOS. In order to resolve these issues, research was conducted into a new design which could utilize key attributes of QCA while also providing a means for near-term fabrication of reliable room-temperature circuits and a path forward for VLSI circuits.The result of this research, presented in this dissertation, is the Lattice-based Integrated-signal Nanocellular Automata (LINA) nanoelectronics paradigm. LINA designs are based on QCA and provide the same basic functionality as traditional QCA. LINA also retains the key attributes of THz switching, scalability to the molecular level, and ability to utilize advanced logical constructs which are crucial to the QCA proposals. However, LINA designs also provide significant improvements over traditional QCA. For example, the continuous correction of faults, due to LINA's integrated-signal approach, provides reliability improvements to enable room-temperature operation with cells which are potentially up to 20nm and fault tolerance to layout, patterning, stray-charge, and stuck-at-faults. In terms of fabrication, LINA's lattice-based structure allows precise relative placement through the use of self-assembly techniques seen in current nanoparticle research. LINA also allows for large enough wire and logic structures to enable use of widely available photo-lithographical patterning technologies. These aspects of the LINA designs, along with power, timing, and clocking results, have been verified through the use of new and/or modified simulation tools specifically developed for this purpose. To summarize, the LINA designs and results, presented in this dissertation, provide a path to realization of QCA-type VLSI nanoelectronic circuitry. Furthermore, they offer a renewed viability of the paradigm to replace CMOS and advance computing technologies beyond the next decade

Synthesis, testing and tolerance in reversible logic

In recent years, reversible computing has established itself as a promising research area and emerging technology. This thesis focuses on three important areas of reversible logic, which is an area of reversible computing. Firstly, this thesis proposes a transformation based synthesis approach for realizing conservative reversible functions using SWAP and Fredkin gates. This thesis also proposes ten templates for optimizing SWAP and Fredkin gates-based reversible circuits. Secondly, this thesis proposes an approach for the design of online testable reversible circuits. A reversible circuit composed of NOT, CNOT and Toffoli gates can be made online testable by adding two sets of CNOT gates and a single parity line. Finally, we have proposed an approach to achieve fault tolerance in reversible circuits. A design of a 3-bit reversible majority voter circuit is presented. This voter circuit can be used to design fault tolerant reversible circuits

Design and synthesis of reversible logic

Energy lost during computation is an important issue for digital design. Today, all electronics devices suffer from energy lost due to the conventional logic system used. The amount of energy loss in the form of heat leads to immense challenges in nowadays circuit design. To overcome that, reversible logic has been invented. Since properties of reversible logic differ greatly than conventional logic, synthesis methods used for conventional logic cannot be used in reversible logic. In this dissertation, we proposed new synthesis algorithms and several circuit designs using reversible logic

Macro environmental challenges and competitive survival in the emerging economies: the role of dynamic managerial capabilities in the Nigerian banking industry

Purpose: the aim of this study is to explore the extent of dynamic managerial capability (DMC) deployment and development by firms in the emerging economies. Design/Methodology/approach: This study follows a critical realism philosophy, and qualitative research method involving semi-structured interviews with senior and middle-level managers in five banks within the Nigerian banking sector to generate data for the study. The interview data were triangulated with data from CEOs’ letters to shareholders over a three year period, press releases, and relevant media reports to assess the extent and how managers deployed and further developed DMC. Data was analysed following a qualitative content analysis technique. Findings: This study in identifying how economic-downturn, regulation, and competition intensity triggered DMC deployment and development in Nigeria, observed that ineffective cognition of resources related to crude-oil income stream, and government financial deposits in Nigeria banks acted as constraints to the extent of DMC deployment and further development. Attention diversity, after two critical events in the industry, enabled asset orchestration that led to firms’ level innovations and capacity building. This study also contributes to a more nuanced understanding of the communication practices enabling DMC by identifying two concepts including buying-in and collegiate systems as processes relevant to better decisions making by managers in the emerging economy. Originality/Value: The study represents an empirical attempt to highlight the significance of resource cognition and to further make a case for attention diversity (AD) in the current discussion on DMC research from the emerging economies context. An integrative model is provided to show how attention diversity enables DMC in the Nigerian banking industry, and also show that collegiate systems and buying-in are communication practices enabling DMC in Nigeria

Shaping the technological landscape: the role of forward-looking cognition in the evolution of robotics

While there is a large amount of literature on the socio-cognitive theory of technology evolution, most has focused on the interpretations of technologies that are already in existence. The literature has barely attended to the role of forward-looking cognition—mental representations of possibilities in the future. How do innovators and entrepreneurs envision the possible, and how do they translate those abstract concepts into new material and social reality? This dissertation first synthesizes the vast literature on technology evolution, and offers a theoretical framework for understanding the role of forward-looking cognition in the evolution of technology. Using a large amount of historical archival data on the US robotics industry, my two empirical papers investigate (a) how a distant vision co-evolves with the actual technologies at the level of the organizational field (b) how entrepreneurial solutions and entrepreneurial search problems are co-constructed at the firm level. In the first paper of my dissertation, I review the literature on the evolution of technology. Over the last decades, scholars from a broad range of theoretical and methodological traditions have generated a vast yet dispersed body of literature on technology evolution. This essay offers a comprehensive synthesis of the major streams of scholarship on technology evolution by dividing the literature into four perspectives: technology realist, economic realist, cognitive interpretivist, and social constructionist. I further show that each perspective offers a divergent account of three central mechanisms—variation, selection, and retention—that drive discrete, continuous, and cyclical patterns of technology evolution. I integrate these perspectives by highlighting that they all emphasize recombination, environmental fit, and path dependence as central drivers of those three mechanisms. I emphasize the need for a co-evolutionary framework that cuts across the four perspectives to push the literature forward. In the second paper of my dissertation, I examine how technological visions—mental representations of technological possibilities in the future—co-evolve with the actual technologies. This paper is set in the robotics industry. The existing literature has focused on how backward-looking interpretations of technology shape its subsequent trajectory, but has rarely examined the role of forward-looking cognition in technology evolution. To examine this, I conducted an extensive archival qualitative study covering the evolution of the field of robotics during the 100-year period from 1921 to 2020. I find that in a future-oriented field, the direction of technology evolution is largely shaped by the field participants’ attempts to narrow the vision-reality gap—the perceived temporal gap between the distant vision and present reality. I identify six distinct mechanisms—linking means to the distant vision, constructing a medium-term vision, envisioning sequences, decomposing, reconstructing, and reintegrating—through which field participants strive to narrow the vision-reality gap. I also find that the vision-reality gap is extremely volatile, and can rapidly expand and contract when salient artifacts (or reverse salients) emerge. In this study, I contribute to the socio-cognitive view of technology by highlighting the role of forward-looking cognition in technology evolution. In the third paper of the dissertation, I study the process through which an entrepreneurial search problem is constructed. Previous studies have focused on search for solutions to a given problem. However, literature on entrepreneurship suggests that many entrepreneurs often start from formulating a very broad, abstract problem that a novel technological means is envisioned to be able to solve in the future. Forward-looking cognition, the mental representations of possibilities in the future, lies behind the process of problem formulation. In order to examine how construction of problems affects search for solutions, I conducted a qualitative analysis of archival data about 58 entrepreneurial firms founded by 42 entrepreneurs in the robotics industry. I find that most entrepreneurial firms start by linking a novel technological means to an abstract problem, and then proactively identify a core constraint in the solution space. In order to bypass the constraint, they engage in decomposing and reconstructing a core problem. In the stage of pursuing product-market fit, the issue of identifying core attributes, or core evaluation criteria weighted by users is brought to the fore. This paper contributes to our understandings of entrepreneurial search by highlighting the cognitive underpinnings of problem formulation