Design tools for rapid multidomain prototyping of power electronic systems

The need for multidisciplinary virtual prototyping in power electronics has been well established however design tools capable of facilitating a rapid, iterative virtual design process do not exist. A key challenge in developing such tools is identifying and developing modelling techniques which can account for 3D, geometrical design choices without unduly affecting simulation speed. This challenge has been addressed in this work using model order reduction techniques and a prototype power electronic design tool incorporating these techniques is presented. A relevant electro-thermal power module design example is then used to demonstrate the performance of the software and model order reduction techniques. Five design iterations can be evaluated, using 3D inductive and thermal models, under typical operating and startup conditions on a desktop PC in less than 15 minutes. The results are validated experimentally for both thermal and electrical domains

Multi‐frequency averaging (MFA) model of a generic electric vehicle powertrain suitable under variable frequency of averaging developed for remote operability

© The Institution of Engineering and Technology 2020. Geographically distributed hardware-in-the-loop (HIL) testing has the potential to allow hybrid vehicle powertrain components (battery, motor drive, and engine) to be developed at geographically remote locations but tested concurrently and coupled. Inter-location internet communication links can allow non-ideal behaviour observed in a physical component in one location (e.g. an electrical drive) to be imposed on another physical component elsewhere (e.g. an ICE), and vice-versa. A key challenge is how to represent the behaviour of a remote, physical component under testing in a local HIL environment. Internet communications are too slow and unreliable to transmit waveforms in real-time and so one solution is to use a local 'slave' model whose behaviour and parameters are tuned based on observations at the remote location. This study proposes a multifrequency averaging (MFA) slave model of an electric motor drive system for use in this application; it addresses a weakness in previously published work by extending the MFA model to variable frequency operation. The model was benchmarked against experimental operation (and its equivalent simulation model) in open-loop and closed-loop space vector pulse-width modulation control strategy, fixed and variable frequency operation. Results show significant reconciliation of model and experiment

Dynamics in inhomogeneous liquids and glasses via the test particle limit

We show that one may view the self and the distinct part of the van Hove dynamic correlation function of a simple fluid as the one-body density distributions of a binary mixture that evolve in time according to dynamical density functional theory. For a test case of soft core Brownian particles the theory yields results for the van Hove function that agree quantitatively with those of our Brownian dynamics computer simulations. At sufficiently high densities the free energy landscape underlying the dynamics exhibits a barrier as a function of the mean particle displacement, shedding new light on the nature of glass formation. For hard spheres confined between parallel planar walls the barrier height oscillates in-phase with the local density, implying that the mobility is maximal between layers, which should be experimentally observable in confined colloidal dispersions.Comment: 4 pages, 3 figure

The Role of Legal Services in the Antipoverty Program

Large-scale adaptive radiations might explain the runaway success of a minority of extant vertebrate clades. This hypothesis predicts, among other things, rapid rates of morphological evolution during the early history of major groups, as lineages invade disparate ecological niches. However, few studies of adaptive radiation have included deep time data, so the links between extant diversity and major extinct radiations are unclear. The intensively studied Mesozoic dinosaur record provides a model system for such investigation, representing an ecologically diverse group that dominated terrestrial ecosystems for 170 million years. Furthermore, with 10,000 species, extant dinosaurs (birds) are the most speciose living tetrapod clade. We assembled composite trees of 614-622 Mesozoic dinosaurs/birds, and a comprehensive body mass dataset using the scaling relationship of limb bone robustness. Maximum-likelihood modelling and the node height test reveal rapid evolutionary rates and a predominance of rapid shifts among size classes in early (Triassic) dinosaurs. This indicates an early burst niche-filling pattern and contrasts with previous studies that favoured gradualistic rates. Subsequently, rates declined in most lineages, which rarely exploited new ecological niches. However, feathered maniraptoran dinosaurs (including Mesozoic birds) sustained rapid evolution from at least the Middle Jurassic, suggesting that these taxa evaded the effects of niche saturation. This indicates that a long evolutionary history of continuing ecological innovation paved the way for a second great radiation of dinosaurs, in birds. We therefore demonstrate links between the predominantly extinct deep time adaptive radiation of non-avian dinosaurs and the phenomenal diversification of birds, via continuing rapid rates of evolution along the phylogenetic stem lineage. This raises the possibility that the uneven distribution of biodiversity results not just from large-scale extrapolation of the process of adaptive radiation in a few extant clades, but also from the maintenance of evolvability on vast time scales across the history of life, in key lineages

Arthritis gene therapy's first death

In July 2007 a subject died while enrolled in an arthritis gene therapy trial. The study was placed on clinical hold while the circumstances surrounding this tragedy were investigated. Early in December 2007 the Food and Drug Administration removed the clinical hold, allowing the study to resume with minor changes to the protocol. In the present article we collate the information we were able to obtain about this clinical trial and discuss it in the wider context of arthritis gene therapy

The Place of Music and Dance in the Reconstruction of African Cultural History: a Case of the Abagusii of South-Western Kenya

This paper presents an overview exposition and critical reflection on the evolution and functionality of the pre-colonial African Music and dance among the Gusii of south-western Kenya. It seeks to address fundamental issues that are on the verge of being forgotten especially by the youth of this generation. It argues that music and dance among the Gusii have traditional roots as serves as a source of understanding the cultural history of the community. Indeed, without knowledge of a community’s cultural history, the historical destiny cannot be easily comprehended. This history makes it one of the most essential genres that the Gusii community’s ethnographic studies. It employs historical approach to explore the past musical and dance generic forms. This paper proceeds from the premise that, in the pre-colonial times, the Gusii had evolved elaborate music and dance forms conditioned by their social and natural environments. It was also established in this discussion that African music and dance, as practiced by the Gusii nurtured, enhanced, preserved and brought up emotionally, psychologically, ethically, socially stable and  a unitary indigenous community. The theories employed to explain the phenomenon of the pre-colonial music and dance were, Evolution, Diffusion, functionalism and theories of dance. The Study methodology into historical enquiry of the place of pre-colonial music and dance was carried out in three major phases as follows; employing data collection techniques on a systematic basis beginning with secondary sources in libraries, the marshalling of primary source materials in the Kenya National Archives, and   the gathering of data through oral interviews and observations in the research field. In this study, respondents were selected through snowball and purposive sampling techniques in order to obtain key custodians of the Gusii cultural history, who at the end of the study proved to be handy by providing up to date valuable information. Oral interviews were conducted between 1996 and 1998.Respondents included sixty elderly men and women from drawn form various parts of Gusii land, both professional and non-professional thought to be knowledgeable on the community’s cultural history. The data collected from both primary and secondary sources was sorted and analyzed qualitatively. From the study findings, it was established that music and dance practices among the Gusii reflected the community’s identity, since they are all, a vital artistic medium, through which people embody the self. This study will contribute to the understanding of African cultural history. Planners in the ministry of culture and social services may use these findings in the planning of socio-cultural activities in perpetuating cultural identity and African history in General. Key words: Abagusii, Reconstruction, Gusii, South-Western Keny

Interfacial and wetting properties of a binary point Yukawa fluid

We investigate the interfacial phase behavior of a binary fluid mixture composed of repulsive point Yukawa particles. Using a simple approximation for the Helmholtz free energy functional, which yields the random phase approximation (RPA) for the pair direct correlation functions, we calculate the equilibrium fluid density profiles of the two species of particles adsorbed at a planar wall. We show that for a particular choice (repulsive exponential) of the wall potentials and the fluid pair-potential parameters, the Euler-Lagrange equations for the equilibrium fluid density profiles may be transformed into a single ordinary differential equation and the profiles obtained by a simple quadrature. For certain other choices of the fluid pair-potential parameters fluid-fluid phase separation of the bulk fluid is observed. We find that when such a mixture is exposed to a planar hard-wall, the fluid exhibits complete wetting on the species 2 poor side of the binodal, i.e. we observe a thick film of fluid rich in species 2 adsorbed at the hard-wall. The thickness of the wetting film grows logarithmically with the concentration difference between the fluid state-point and the binodal and is proportional to the bulk correlation length of the intruding (wetting) fluid phase. However, for state points on the binodal that are further from the critical point, we find there is no thick wetting film. We determine the accompanying line of first-order (pre-wetting) surface phase transitions which separate a thin and thick adsorbed film. We show that for some other choices of repulsive wall potentials the pre-wetting line is still present, but its location and extent in the phase diagram is strongly dependent on the wall-fluid interaction parameters.Comment: 11 pages, 7 figures. Accepted for publication in Journal of Chemical Physic

Determining Plant – Leaf Miner – Parasitoid Interactions: A DNA Barcoding Approach

A major challenge in network ecology is to describe the full-range of species interactions in a community to create highly-resolved food-webs. We developed a molecular approach based on DNA full barcoding and mini-barcoding to describe difficult to observe plant – leaf miner – parasitoid interactions, consisting of animals commonly regarded as agricultural pests and their natural enemies. We tested the ability of universal primers to amplify the remaining DNA inside leaf miner mines after the emergence of the insect. We compared the results of a) morphological identification of adult specimens; b) identification based on the shape of the mines; c) the COI Mini-barcode (130 bp) and d) the COI full barcode (658 bp) fragments to accurately identify the leaf-miner species. We used the molecular approach to build and analyse a tri-partite ecological network of plant – leaf miner – parasitoid interactions. We were able to detect the DNA of leaf-mining insects within their feeding mines on a range of host plants using mini-barcoding primers: 6% for the leaves collected empty and 33% success after we observed the emergence of the leaf miner. We suggest that the low amplification success of leaf mines collected empty was mainly due to the time since the adult emerged and discuss methodological improvements. Nevertheless our approach provided new species-interaction data for the ecological network. We found that the 130 bp fragment is variable enough to identify all the species included in this study. Both COI fragments reveal that some leaf miner species could be composed of cryptic species. The network built using the molecular approach was more accurate in describing tri-partite interactions compared with traditional approaches based on morphological criteria

Continuity of Optimal Control Costs and its application to Weak KAM Theory

We prove continuity of certain cost functions arising from optimal control of affine control systems. We give sharp sufficient conditions for this continuity. As an application, we prove a version of weak KAM theorem and consider the Aubry-Mather problems corresponding to these systems.Comment: 23 pages, 1 figures, added explanations in the proofs of the main theorem and the exampl