MRC Laboratory of Molecular Biology
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The transient voltage response of ReBCO coated conductors exhibiting dynamic resistance
No full textDynamic resistance can be observed in a superconducting tape carrying a DC current which is exposed to an oscillating magnetic field. This effect is attributed to the interaction between the transport current and moving fluxons, and can occur in various superconducting components including high temperature superconducting (HTS) flux pumps, fast-ramping magnets and HTS rotating machines. Although conventionally expressed in terms of a DC 'resistance,' the phenomenon is inherently transient in nature, and the voltage drop across the superconductor follows a time-dependent periodic waveform. Here we present experimental measurements of the dynamic resistance of different REBCO tapes carrying a DC current and exposed to an oscillating perpendicular field. Measurements of both the transient voltage waveforms and the time-Averaged DC resistances are compared with numerical finite element simulations obtained using the H-formulation. We observe clear variations between the voltage response from different tapes, which can be understood in terms of their differing J c(B, θ) dependence. In particular, a key feature of the experimentally measured waveforms is the emergence of a split 'double peak' at higher applied fields. Graphical visualisations of the finite element data show that this coincides with a periodic increase in J c(B, θ) throughout the tape. This occurs during each cycle at those times when the applied field falls below the shielding threshold of the tape (as the penetrating field within the tape then approaches zero). Our findings show that models which assume a constant J c irrespective of local field strength cannot capture the full range of behaviour observed by experiment. This emphasises the importance of employing experimentally measured J c(B, θ) data when simulating transient effects in HTS materials
An Empirical Study on Construction Process Corruption Susceptibility: A Vignette of International Expertise
No full textConstruction process stages are argued to be vulnerable to the prevalence of corrupt practices. However, the validity of this argument has not been empirically explored in the extant literature of construction management. Therefore, this study examines the stages of the construction process susceptibility to corruption and its most prominent forms of corrupt activities (within the respective stages). A total of forty-four project-related professionals were involved in an expert survey to assess such susceptibilities and the criticality of the identified corrupt activities at each stage. A comparative study of expert views from developing regions against experts from developed regions is conducted. Expert scoring results revealed that three stages are most susceptible, namely: project execution, pre-qualification and tender stages. Such results were confirmed by application of the Mann–Whitney U test statistics tool, showing wide disparities in seven out of eleven identical stages. This study is intended to incite polemic discussions and greater empirical, evidence-based research from scholars in both developed and developing countries. This study adds to the extant literature corruption-related works on the construction process through deeper understanding of the dynamic nature of corrupt practices involved in the stages of the construction process in developing countries. Practically, it intends to offer a veritable plethora of information on the critical stages of the construction process for industry practitioners, policymakers and anti-corruption bodies to careen their attention towards the fight against corruption
Deprecated in policy, abundant in market? The frugal innovation of Chinese low-speed EV industry
No full textIn the era of “Industry 4.0”, individualized demand and small batch customization manufacturing will become the trend, which calls for strong capabilities of customer orientation and rapid reaction. In addition to the redesign of smart and autonomous production processes, the market-oriented frugal innovation is a valuable exploration under the framework of “Industry 4.0”. This paper anchors itself at a deprecated policy context to study frugal innovation patterns and their forming mechanisms, which is still a rarely touched area. By selecting as its cases Shifeng, Baoya and Taiqi from the Shandong province, China, this paper uses a qualitative approach to analyze low-speed electric vehicle (EV) businesses according to a three-dimension frugal innovation framework composed by business ecosystem (BE) configurations, BE capabilities and innovation process. The findings are as follows, (1) there are three typical frugal innovation patterns, namely market-based persistence, market-based contingency and technology-based contingency, which help frugal innovators obtain an abundant market performance even under a deprecated policy environment; (2) a vertical integration network and strong marketing capabilities are the capital to select a market-based persistence pattern, while the lack of some substantial resources and capabilities compels firms to have to adopt a more flexible way of frugal innovation in order to carve out a safe niche. This paper contributes to frugal innovation research by exploring a new deprecated policy context rather than traditional institution voids, constructing a frugal innovation framework from the BE perspective by focusing on focal firms, and proposing three frugal innovation patterns under different resource constraints. From the practical side, this paper suggests that future innovation policy should balance advanced technology requirements and practical market demands, and the governments should also emphasize market positioning and demand orientation in the process of Industry 4.0 transformation
Breaking the cycle of frustration: Applying Neisser's Perceptual Cycle Model to drivers of semi-autonomous vehicles
No full textSemi-autonomous cars are already on the road and highly autonomous cars will soon be with us. Little is understood about how drivers will adapt to the changing relationship with their vehicle, but to ensure safety and consumer acceptance, this insight is vital. To this end, an on-road study in a semi-autonomous vehicle was undertaken with six UK drivers. The ‘think aloud’ technique was employed and video and audio footage of their interaction with the vehicle was captured. Neisser's (1976) Perceptual Cycle Model (PCM) was used to analyse the data and three case studies are presented to highlight how poor synergy between driver and semi-autonomous vehicles can occur from the lens of Schema, Action or World information. Seven key design considerations are proposed to ensure a more positive and safer interaction between driver and autonomous vehicle to guide focus by manufacturers. Further evidence for the existence of a ‘counter cycle’ (Plant and Stanton, 2015) within the PCM is found and how this relates to the challenges of using verbal protocals expressed during a fast moving dynamic task is discussed
Customer experience management in the age of big data analytics: A strategic framework
No full textCustomer experience (CX) has emerged as a sustainable source of competitive differentiation. Recent developments in big data analytics (BDA) have exposed possibilities to unlock customer insights for customer experience management (CXM). Research at the intersection of these two fields is scarce and there is a need for conceptual work that (1) provides an overview of opportunities to use BDA for CXM and (2) guides management practice and future research. The purpose of this paper is therefore to develop a strategic framework for CXM based on CX insights resulting from BDA. Our conceptualisation is comprehensive and is particularly relevant for researchers and practitioners who are less familiar with the potential of BDA for CXM. For managers, we provide a step-by-step guide on how to kick-start or implement our strategic framework. For researchers, we propose some opportunities for future studies in this promising research area
Non-Circulatory Force on a Finite Thickness Body Encountering a Gust
No full textMany low-order models for unsteady flows divide the force into circulatory and non-circulatory components. The former is associated with vorticity in the flow field, whilst the latter is often synonymous with the added mass force. Investigating a cylinder sharp-edged gust encounter, at a Reynolds number of 6000, probes the origin of these respective forces. Vorticity residing in the flow field does not only originate from the cylinder but it is also located in the gust shear layers, which delimit the vertical gust velocity from the surrounding quiescent fluid. It is possible to represent the body surface by a vortex sheet where individual components, satisfying the non-through flow condition, originate from different sources. All vorticity external to the body generates a complementary contribution to this surface vortex sheet. A further vortex sheet component is uniquely attributed to linear acceleration of a body and linked to the added mass effect. Finally, a non-circulatory vortex sheet forms due to the induced velocity by the gust vorticity. In Küssner's potential flow gust model this latter vortex sheet contribution is attributed to added mass. However, because the gust encounter is not associated with any body acceleration, the force must rather be linked to the growth and redistribution of this vortex sheet, due to the relative advection of the gust shear layer vorticity. Particle image velocimetry validates this result using a surging and rotating cylinder at gust ratios of 0.5 and 1. Force balance measurements show that the force originating from the rate of change of the non-circulatory gust vortex sheet, unlike in the case for an infinitely thin plate, vastly over-predicts the initial rise in force as the cylinder enters the gust. This is because, when considering the rate of change of the vortex sheet, it is implicitly assumed that all of the vertical momentum of the gust flow inside the region occupied by the cylinder, is lost. The overestimation is a result of the rigid shear layer assumption inherent to the Küssner model. In reality, the gust shear layers deflect, causing a spread of vertical momentum. The deflection of the shear layers can be analytically approximated by removing the contribution due to the rate of change of momentum inside the cylinder. This improves the force prediction but does not fully recover the experimental force measurements during the initial entry into the gust. On a practical level this suggests that for bodies of finite thickness the non-circulatory force cannot be easily calculated, as it is difficult to quantify the effect of the body volume
An application of HRI in low-cost digital manufacturing
No full textDigital Manufacturing (DM) broadly refers to applying digital information to enhance manufacturing processes, supply chains, products and services. In past work we proposed a low-cost DM architecture, supporting flexible integration of legacy robots. Here we discuss a demo of our architecture using an HRI scenario
Model-free robust optimal feedback mechanisms of biological motor control
No full textSensorimotor tasks that humans perform are often affected by different sources of uncertainty. Nevertheless, the central nervous system (CNS) can gracefully coordinate our movements. Most learning frameworks rely on the internal model principle, which requires a precise internal representation in the CNS to predict the outcomes of our motor commands. However, learning a perfect internal model in a complex environment over a short period of time is a nontrivial problem. Indeed, achieving proficient motor skills may require years of training for some difficult tasks. Internal models alone may not be adequate to explain the motor adaptation behavior during the early phase of learning. Recent studies investigating the active regulation of motor variability, the presence of suboptimal inference, and model-free learning have challenged some of the traditional viewpoints on the sensorimotor learning mechanism. As a result, it may be necessary to develop a computational framework that can account for these new phenomena. Here, we develop a novel theory of motor learning, based on model-free adaptive optimal control, which can bypass some of the difficulties in existing theories. This new theory is based on our recently developed adaptive dynamic programming (ADP) and robust ADP (RADP) methods and is especially useful for accounting for motor learning behavior when an internal model is inaccurate or unavailable. Our preliminary computational results are in line with experimental observations reported in the literature and can account for some phenomena that are inexplicable using existing models
Aeroacoustics of Silent Owl Flight
No full textThe ability of some species of owl to fly in effective silence is unique among birds and provides a distinct hunting advantage, but it remains a mystery as to exactly what aspects of the owl and its flight are responsible for this dramatic noise reduction. Crucially, this mystery extends to how the flow physics may be leveraged to generate noise-reduction strategies for wider technological application. We review current knowledge of aerodynamic noise from owls, ranging from live owl noise measurements to mathematical modeling and experiments focused on how owls may disrupt the standard routes of noise generation. Specialized adaptations and foraging strategies are not uniform across all owl species: Some species may not have need for silent flight, or their evolutionary adaptations may not be effective for useful noise reduction for certain species. This hypothesis is examined using mathematical models and borne out where possible by noise measurements and morphological observations of owl feathers and wings
Material Flow Analysis with Multiple Material Characteristics to Assess the Potential for Flat Steel Prompt Scrap Prevention and Diversion without Remelting
No full textThirty-two percent of the liquid metal used to make flat steel products in Europe does not end up in a final product. Sixty percent of this material is instead scrapped during manufacturing and the remainder during fabrication of finished steel products. Although this scrap is collected and recycled, remelting this scrap requires approximately 2 MWh/t, but some of this material could instead be diverted for use in other applications without remelting. However, this diversion depends not just on the mass of scrapped steel but also on its material characteristics. To enhance our understanding of the potential for such scrap diversion, this paper presents a novel material flow analysis of flat steel produced in Europe in 2013. This analysis considers the flow of steel characterized not only by mass but, for the first time, also by grade, thickness, and coating. The results show that thin-gauge galvanized drawing steel is the most commonly demanded steel grade across the industry, and most scrap of this grade is generated by the automotive industry. There are thus potential opportunities for preventing and diverting scrap of this grade. We discuss the role of the geometric compatibility of parts and propose tessellating blanks for various car manufacturers in the same coil of steel to increase the utilization rates of steel