13,125 research outputs found
Beam scanning by liquid-crystal biasing in a modified SIW structure
A fixed-frequency beam-scanning 1D antenna based on Liquid Crystals (LCs) is designed for application in 2D scanning with lateral alignment. The 2D array environment imposes full decoupling of adjacent 1D antennas, which often conflicts with the LC requirement of DC biasing: the proposed design accommodates both. The LC medium is placed inside a Substrate Integrated Waveguide (SIW) modified to work as a Groove Gap Waveguide, with radiating slots etched on the upper broad wall, that radiates as a Leaky-Wave Antenna (LWA). This allows effective application of the DC bias voltage needed for tuning the LCs. At the same time, the RF field remains laterally confined, enabling the possibility to lay several antennas in parallel and achieve 2D beam scanning. The design is validated by simulation employing the actual properties of a commercial LC medium
An empirical investigation of the relationship between integration, dynamic capabilities and performance in supply chains
This research aimed to develop an empirical understanding of the relationships between integration,
dynamic capabilities and performance in the supply chain domain, based on which, two conceptual
frameworks were constructed to advance the field. The core motivation for the research was that, at
the stage of writing the thesis, the combined relationship between the three concepts had not yet
been examined, although their interrelationships have been studied individually.
To achieve this aim, deductive and inductive reasoning logics were utilised to guide the qualitative
study, which was undertaken via multiple case studies to investigate lines of enquiry that would
address the research questions formulated. This is consistent with the authorâs philosophical
adoption of the ontology of relativism and the epistemology of constructionism, which was considered
appropriate to address the research questions. Empirical data and evidence were collected, and
various triangulation techniques were employed to ensure their credibility. Some key features of
grounded theory coding techniques were drawn upon for data coding and analysis, generating two
levels of findings. These revealed that whilst integration and dynamic capabilities were crucial in
improving performance, the performance also informed the former. This reflects a cyclical and
iterative approach rather than one purely based on linearity. Adopting a holistic approach towards
the relationship was key in producing complementary strategies that can deliver sustainable supply
chain performance.
The research makes theoretical, methodological and practical contributions to the field of supply
chain management. The theoretical contribution includes the development of two emerging
conceptual frameworks at the micro and macro levels. The former provides greater specificity, as it
allows meta-analytic evaluation of the three concepts and their dimensions, providing a detailed
insight into their correlations. The latter gives a holistic view of their relationships and how they are
connected, reflecting a middle-range theory that bridges theory and practice. The methodological
contribution lies in presenting models that address gaps associated with the inconsistent use of
terminologies in philosophical assumptions, and lack of rigor in deploying case study research
methods. In terms of its practical contribution, this research offers insights that practitioners could
adopt to enhance their performance. They can do so without necessarily having to forgo certain
desired outcomes using targeted integrative strategies and drawing on their dynamic capabilities
Distributed Sensing, Computing, Communication, and Control Fabric: A Unified Service-Level Architecture for 6G
With the advent of the multimodal immersive communication system, people can
interact with each other using multiple devices for sensing, communication
and/or control either onsite or remotely. As a breakthrough concept, a
distributed sensing, computing, communications, and control (DS3C) fabric is
introduced in this paper for provisioning 6G services in multi-tenant
environments in a unified manner. The DS3C fabric can be further enhanced by
natively incorporating intelligent algorithms for network automation and
managing networking, computing, and sensing resources efficiently to serve
vertical use cases with extreme and/or conflicting requirements. As such, the
paper proposes a novel end-to-end 6G system architecture with enhanced
intelligence spanning across different network, computing, and business
domains, identifies vertical use cases and presents an overview of the relevant
standardization and pre-standardization landscape
Serving to secure "Global Korea": Gender, mobility, and flight attendant labor migrants
This dissertation is an ethnography of mobility and modernity in contemporary South Korea (the Republic of Korea) following neoliberal restructuring precipitated by the Asian Financial Crisis (1997). It focuses on how comparative âservice,â âsecurity,â and âsafetyâ fashioned âGlobal Koreaâ: an ongoing state-sponsored project aimed at promoting the economic, political, and cultural maturation of South Korea from a once notoriously inhospitable, âbackwardâ country (hujinâguk) to a now welcoming, âadvanced countryâ (sĆnjinâguk). Through physical embodiments of the culturally-specific idiom of âsuperiorâ service (sĆbisĆ), I argue that aspiring, current, and former Korean flight attendants have driven the production and maintenance of this national project.
More broadly, as a driver of this national project, this occupation has emerged out of the countryâs own aspirational flights from an earlier history of authoritarian rule, labor violence, and xenophobia. Against the backdrop of the Korean stateâs aggressive neoliberal restructuring, globalization efforts, and current âHell Chosunâ (HelchosĆn) economy, a group of largely academically and/or class disadvantaged young women have been able secure individualized modes of pleasure, self-fulfillment, and class advancement via what I deem âservice mobilities.â Service mobilities refers to the participation of mostly women in a traditionally devalued but growing sector of the global labor market, the âpink collarâ economy centered around âfeminineâ care labor. Korean female flight attendants share labor skills resembling those of other foreign labor migrants (chiefly from the âGlobal Southâ), who perform care work deemed less desirable. Yet, Korean female flight attendants elude the stigmatizing, classed, and racialized category of âlabor migrant.â Moreover, within the context of South Koreaâs unique history of rapid modernization, the flight attendant occupation also commands considerable social prestige.
Based on ethnographic and archival research on aspiring, current, and former Korean flight attendants, this dissertation asks how these unique care laborers negotiate a metaphorical and literal series of sustained border crossings and inspections between Korean flight attendantsâ contingent status as lowly care-laboring migrants, on the one hand, and ostensibly glamorous, globetrotting elites, on the other. This study contends the following: first, the flight attendant occupation in South Korea represents new politics of pleasure and pain in contemporary East Asia. Second, Korean female flight attendantsâ enactments of soft, sanitized, and glamorous (hwaryĆhada) service help to purify South Koreaâs less savory past. In so doing, Korean flight attendants reconstitute the historical role of female laborers as burden bearers and caretakers of the Korean state.U of I OnlyAuthor submitted a 2-year U of I restriction extension request
Empowering Practitioners: A Conceptual Framework for Value Co-Creation through Smart Service Innovation Methodologies
Smart services offer great innovation potential by incorporating digital technologies into non-digital value-creation processes. As smart service innovation poses significant challenges to organizations, existing research has contributed to understanding and addressing this phenomenon by developing various methods, tools, and processes. Yet, the academic community often still fails to bridge the âlast mileâ and help practitioners apply this knowledge in their specific application contexts. This article outlines how research can empower practitioners by systematically providing methodological knowledge for smart service innovation. We review and contrast existing methodologies and present a conceptual framework for value co-creation through smart service innovation methodologies. In addition, we identify six essential resource types required in these methodologies and propose emergent research avenues to guide future contributions to smart service innovation research
Advanced Control of a Multi-Port Autonomous Reconfigurable Solar Power Plant
The multi-port autonomous reconfigurable solar power plant (MARS), which is an integration of photovoltaic (PV) and energy storage system (ESS) to the transmission ac grid and a high-voltage direct current (HVdc) link, is designed to provide frequency response and reject disturbances in the grid with continued operation and reduced transient instability. The complex architecture of the MARS and the intermittent nature of PV underlies the need for developing simple, efficient, and easily generalizable control methods for MARS and MARS-type systems that integrate multiple power sources to the submodules (SMs) in each arm. The presence of different sources such as PV and ESS in each arm of the MARS causes uneven distribution of active power among different SMs present in MARS, thereby leading to unbalanced modulesâ capacitor voltages that may impact system stability under various operating conditions. Moreover, in the case of partial shadings, shaded PV SMs will suffer from decreased injected PV power, causing power mismatch between different SMs in the MARS system. An energy balancing control (EBC) method is introduced to balance the capacitor voltages of different types of SMs. Moreover, the system operation region is explored through data-driven method and a machine learning-based EBC criteria are proposed to improve the system efficiency and reduce the switching frequency. The proposed EBC criteria can disable/enable the EBC depending on the MARS input power dispatch commands with high accuracy according to the operation region. To simplify the design process and improved the system performance, the thesis further proposed a neural network-based power mismatch elimination (NNPME) strategy. The NNPME strategy employs ESS to its maximum capacity and the dc and ac circulating currents to transfer power between the SMs, arms, and legs of the MARS and stabilize the system under partial shedding conditions. The aforementioned controls are data-driven methods that require a large amount of simulation data. A model predictive control (MPC) is proposed for more accurate and efficient control of MARS. It can optimally allocate uneven power of ESS and PV in one arm and counteract capacitor voltage deviations. The system dynamic response is largely improved with the implementation of MPC. The proposed advanced controls facilitate the efficient control and energy management of a system with multiple input power sources like MARS to fully utilize its potential with an extended operating region while maintaining high efficiency.Ph.D
A Hybrid Platform for Wideband Reconfigurable Nonlinear Metamaterials
Optical frequency conversion processes, such as second- and third-harmonic generations, are commonly realized in nonlinear optics, offering application opportunities in photonics, chemistry, material science, and biosensing. Limited by intrinsically weak nonlinear responses of bulk materials, complex phase-matching techniques are typically required to realize significant nonlinear frequency conversions. Frequency preserving nonlinear processes, such as the optical Kerr effect, have potential for computing applications, due to efficient optical-intensity-dependent operations. Metamaterials and metasurfaces of artificially engineered and properly ordered building block arrays have been introduced to manipulate linear and nonlinear light-matter interactions at the subwavelength scale. I leverage high-refractive-index phase-change materials (PCMs) germanium antimony telluride (GST) and antimony sulfide (Sb2S3) that inherently exhibit strongly active tunable large optical nonlinearities to enhance the tunability of nonlinear metamaterials and metasurfaces in this thesis. I also demonstrate enhanced optical nonlinearities in passive high-index silicon (Si)-based metasurfaces that have various mode engineering opportunities and are easy to fabricate with mature techniques. The objective of research in this thesis is to demonstrate a hybrid platform for wideband reconfigurable nonlinear photonic metamaterials. The platform is composed of hybridized reconfigurable PCMs GST and Sb2S3 as well as static Si nano-building blocks. In the PCM-based research part, I demonstrate wideband-tunable third-harmonic generation (THG) devices with subwavelength features using multiple crystallinity states of GST. I also demonstrate efficient fixed-band second-harmonic generation and THG switches with metamaterials based on and tuned by GST, respectively. Additionally, I numerically demonstrate all-Sb2S3 linear and THG metasurfaces for tunable focusing. These structures are of interest for on-chip nonlinear optical imaging, microscopy, and communication applications. The Si-based research part is focused on the use of high-quality-factor bound states in the continuum resonance phenomena and a deep learning technique to accelerate designing efficient nonlinear all-Si metasurfaces. These demonstrations have several potentials for addressing the existing challenges in nonlinear optical computing.Ph.D
Modelling, Monitoring, Control and Optimization for Complex Industrial Processes
This reprint includes 22 research papers and an editorial, collected from the Special Issue "Modelling, Monitoring, Control and Optimization for Complex Industrial Processes", highlighting recent research advances and emerging research directions in complex industrial processes. This reprint aims to promote the research field and benefit the readers from both academic communities and industrial sectors
Feedback-Based Channel Frequency Optimization in Superchannels
Superchannels leverage the flexibility of elastic optical networks and pave
the way to higher capacity channels in space division multiplexing (SDM)
networks. A superchannel consists of subchannels to which continuous spectral
grid slots are assigned. To guarantee superchannel operation, we need to
account for soft failures, e.g., laser drifts causing interference between
subchannels, wavelength-dependent performance variations, and filter
misalignments affecting the edge subchannels. This is achieved by reserving
spectral guardband between subchannels or by employing a lower modulation
format. We propose a process that dynamically retunes the subchannel
transmitter (TX) lasers to compensate for soft failures during operation and
optimizes the total capacity or the minimum subchannel quality of transmission
(QoT) performance. We use an iterative stochastic subgradient method that at
each iteration probes the network and leverages monitoring information,
particularly subchannels signal-to-noise ratio (SNR) values, to optimize the TX
frequencies. Our results indicate that our proposed method always approaches
the optima found with an exhaustive search technique, unsuitable for operating
networks, irrespective of the subchannel number, modulation format, roll-off
factor, filters bandwidth, and starting frequencies. Considering a
four-subchannel superchannel, the proposed method achieves 2.47 dB and 3.73 dB
improvements for a typical soft failure of +/- 2 GHz subchannel frequency
drifts around the optimum, for the two examined objectives
Artificial Intelligence (AI) and Business Innovation in Insurance: A Comparison of Incumbent Firms versus New Entrants
Artificial Intelligence (AI) systems evolve in response to new data by using adaptive algorithms. The insurance industry is data intensive, and dynamic. It is therefore particularly suitable for AI implementation. An innovation triangle framework is proposed that consists of product, process and value chain innovation. A comparison of leading incumbent insurance firms with new entrants illustrates significant competitive differences. The incumbents apply AI to defend their market positions by enhancing existing strengths and capabilities across the three innovation types. The new entrants exploit AI technology to build new products with innovative features that emphasise customer value and user experience. The innovation triangle is a useful managerial tool to analyse the nature and extent of innovation in insurance and can be used to evaluate and plan AI strategies by mapping existing AI initiatives to specific types of innovation and identifying innovation objectives and opportunities. Future trends and research opportunities are outlined
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