Design of a Grid-Forming, Multi-Loop Control Scheme for Parallel Connected, Three-Phase Quasi-Z-Source Inverters

The quasi-Z-source inverter has been the subject of numerous power electronics publications since its invention in the early 2000s. While often applied as an interface for renewable energies such as wind and PV, there is a lack of literature where the qZSI functions in a grid-forming role. The goal of this work is to design and implement a control scheme for a 3-phase qZSI in order to enable it to operate in a grid-forming role. The qZSI is analyzed in great detail and compared to a conventional voltage source inverter scheme that is commonly used in renewable energy interfaces. Literature is presented to demonstrate the need for current programmed mode (CPM) control for the dc side of the qZSI, and the control scheme is compared to a common control scheme used for boost converters. Then, recent literature is presented to support why the universal droop control (UDC) scheme was chosen for the ac-side control for this work. After contextualizing the design of the overall qZSI control scheme, the final control scheme is presented, which utilizes CPM indirect control on the dc-side, and UDC on the ac side. The stability and dynamic response of the system is analyzed in detail for the chosen gains and component values. Through PLECS simulations, the qZSI system presented in this work demonstrated its ability to operate in a grid-forming role and potentially superior performance when compared to conventional VSI systems. While a much more optimized design approach is needed for both the qZSI and VSI to truly compare the two systems, this work demonstrates that the qZSI is more than capable of operating in a grid-forming role. It handles large step changes in load and input voltage with quick rise times and good damping, and exhibits quick and stable responses when operating in parallel with other inverters. This work concludes with some considerations for future work on this topic

Hsp-90 and the biology of nematodes

BACKGROUND: Hsp-90 from the free-living nematode Caenorhabditis elegans is unique in that it fails to bind to the specific Hsp-90 inhibitor, geldanamycin (GA). Here we surveyed 24 different free-living or parasitic nematodes with the aim of determining whether C. elegans Hsp-90 was the exception or the norm amongst the nematodes. We combined these data with codon evolution models in an attempt to identify whether hsp-90 from GA-binding and non-binding species has evolved under different evolutionary constraints.<BR/>RESULTS: We show that GA-binding is associated with life history: free-living nematodes and those parasitic species with free-living larval stages failed to bind GA. In contrast, obligate parasites and those worms in which the free-living stage in the environment is enclosed within a resistant egg, possess a GA-binding Hsp-90. We analysed Hsp-90 sequences from fifteen nematode species to determine whether nematode hsp-90s have undergone adaptive evolution that influences GA-binding. Our data provide evidence of rapid diversifying selection in the evolution of the hsp-90 gene along three separate lineages, and identified a number of residues showing significant evidence of adaptive evolution. However, we were unable to prove that the selection observed is correlated with the ability to bind geldanamycin or not.<BR/>CONCLUSION: Hsp-90 is a multi-functional protein and the rapid evolution of the hsp-90 gene presumably correlates with other key cellular functions. Factors other than primary amino acid sequence may influence the ability of Hsp-90 to bind to geldanamycin

Decision making in Engineering Projects

Even though risk management is a vital aspect of project management, the way that risk-based decisions are taken in projects is not well documented. Economic theory employs the concept of utility and assumes that decision makers are rational. Behavioural economics and prospect theory challenge this idea, making a number of specific claims about how decision-making behaviour deviates from rationality in practice. Based on a focus group discussion with project managers, this research highlights the importance of risk management in underpinning decision making and investigates the extent of rationality and applicability of prospect theory in an engineering project context. Prospect theory’s claims of reference dependence and loss aversion are found to be important, but the claims of diminishing sensitivity and probability weighting appear to be less relevant

Transposon insertion mapping with PIMMS, Pragmatic Insertional Mutation Mapping System

The PIMMS (Pragmatic Insertional Mutation Mapping System) pipeline has beendeveloped for simple conditionally essential genome discovery experiments in bacteria.Capable of using raw sequence data files alongside a FASTA sequence of thereference genome and GFF file, PIMMS will generate a tabulated output of each codingsequence with corresponding mapped insertions accompanied with normalized resultsenabling streamlined analysis. This allows for a quick assay of the genome to identifyconditionally essential genes on a standar d desktop computer prioritizing results forfurther investigation

A Journey Toward Learner-Centered Curriculum

In higher education, competing demands for accountability and innovation in the face of globalization, technology, and budget cuts cause us to consider how best to prepare learners who will learn for a lifetime. We contend that a shift in our understanding of curriculum design to accommodate learner-centeredness will provide the framework for preparing graduates for a lifetime of learning. Learner-centered curriculum proposes to create highly developed individuals, providing them the skills to continue creating learning experiences, digest current knowledge, and create new knowledge within the curriculum itself. Curriculum characteristics, as identified in the curriculum design project presented here, include content appropriate to the characteristics of a new society. It also includes all that is required of a curriculum in order for it to be transparent and easily understood as the scaffolding of learning. This definition of a learner-centered curriculum includes components that educators deem to be relevant and vital for students. It adds curriculum processes and required outcomes to prepare students for curriculum creation alongside educators.Au niveau des études supérieures, les exigences pour la responsabilité et l'innovation face à la globalisation, la technologie, et aux coupures budgétaires nous poussent à considérer comment mieux former ceux qui apprendront tout au long de leur vie. Nous croyons qu'un changement de notre compréhension de la planification du curriculum, davantage centrée sur l'apprenant, fournira un encadrement pour préparer les diplômés pour une vie d'apprentissage. Ce type de curriculum tend à développer chez les individus des habilités qui leur permettront de continuer leurs expériences d'apprentissages, d'acquérir des connaissances et même d'améliorer le curriculum. Les caractéristiques du curriculum, définies dans le projet de planification présenté ici, prennent en considération les caractéristiques d'une nouvelle société. Elles incluent également tout ce qui est nécessaire pour qu'un curriculum soit transparent et facilement compris comme structure visant l'apprentissage. Cette définition de la planification du curriculum inclut des facteurs que les éducateurs trouveront utiles et vitaux pour les étudiants. Sont aussi présentés des processus de curriculum et des résultats attendus afin de préparer les étudiants à collaborer avec les éducateurs à la création d'un curriculum

Identification of DNA methylation biomarkers from Infinium arrays

Epigenetic modifications of DNA, such as cytosine methylation are differentially abundant in diseases such as cancer. A goal for clinical research is finding sites that are differentially methylated between groups of samples to act as potential biomarkers for disease outcome. However, clinical samples are often limited in availability, represent a heterogeneous collection of cells or are of uncertain clinical class. Array based methods for identification of methylation provide a cost effective method to survey a proportion of the methylome at single base resolution. The Illumina Infinium array has become a popular and reliable high throughput method in this field and are proving useful in the identification of biomarkers for disease. Here, we compare a commonly used statistical test with a new intuitive and flexible computational approach to quickly detect differentially methylated sites. The method rapidly identifies and ranks candidate lists with greatest inter-group variability whilst controlling for intra-group variability. Intuitive and biologically relevant filters can be imposed to quickly identify sites and genes of interest

Diverse Spatial, Temporal, and Sexual Expression of Recently Duplicated Androgen-Binding Protein Genes in \u3ci\u3eMus musculus\u3c/i\u3e

Background The genes for salivary androgen-binding protein (ABP) subunits have been evolving rapidly in ancestors of the house mouse Mus musculus, as evidenced both by recent and extensive gene duplication and by high ratios of nonsynonymous to synonymous nucleotide substitution rates. This makes ABP an appropriate model system with which to investigate how recent adaptive evolution of paralogous genes results in functional innovation (neofunctionalization). Results It was our goal to find evidence for the expression of as many of the Abp paralogues in the mouse genome as possible. We observed expression of six Abpa paralogues and five Abpbg paralogues in ten glands and other organs located predominantly in the head and neck (olfactory lobe of the brain, three salivary glands, lacrimal gland, Harderian gland, vomeronasal organ, and major olfactory epithelium). These Abp paralogues differed dramatically in their specific expression in these different glands and in their sexual dimorphism of expression. We also studied the appearance of expression in both late-stage embryos and postnatal animals prior to puberty and found significantly different timing of the onset of expression among the various paralogues. Conclusion The multiple changes in the spatial expression profile of these genes resulting in various combinations of expression in glands and other organs in the head and face of the mouse strongly suggest that neofunctionalization of these genes, driven by adaptive evolution, has occurred following duplication. The extensive diversification in expression of this family of proteins provides two lines of evidence for a pheromonal role for ABP: 1) different patterns of Abpa/Abpbg expression in different glands; and 2) sexual dimorphism in the expression of the paralogues in a subset of those glands. These expression patterns differ dramatically among various glands that are located almost exclusively in the head and neck, where the sensory organs are located. Since mice are nocturnal, it is expected that they will make extensive use of olfactory as opposed to visual cues. The glands expressing Abp paralogues produce secretions (lacrimal and salivary) or detect odors (MOE and VNO) and thus it appears highly likely that ABP proteins play a role in olfactory communication

Duplicated Paralogous Genes Subject to Positive Selection in the Genome of Trypanosoma brucei

Background Whole genome studies have highlighted duplicated genes as important substrates for adaptive evolution. We have investigated adaptive evolution in this class of genes in the human parasite Trypanosoma brucei, as indicated by the ratio of non-synonymous (amino-acid changing) to synonymous (amino acid retaining) nucleotide substitution rates. Methodology/Principal Findings We have identified duplicated genes that are most rapidly evolving in this important human parasite. This is the first attempt to investigate adaptive evolution in this species at the codon level. We identify 109 genes within 23 clusters of paralogous gene expansions to be subject to positive selection. Conclusions/Significance Genes identified include surface antigens in both the mammalian and insect host life cycle stage suggesting that competitive interaction is not solely with the adaptive immune system of the mammalian host. Also surface transporters related to drug resistance and genes related to developmental progression are detected. We discuss how adaptive evolution of these genes may highlight lineage specific processes essential for parasite survival. We also discuss the implications of adaptive evolution of these targets for parasite biology and control