Development of a Generic Time-to-Contact Pilot Guidance Model

The time-to-contact ττ theory posits that purposeful actions can be conducted by coupling the actor’s motion onto the so-called ττ guides generated internally by their central nervous system. Although significant advances have been made in the application of ττ for flight control purposes, little research has been conducted to investigate how pilots are able to adapt their ττ-guidance strategy to different aircraft dynamics, or how a ττ-guide-based pilot–aircraft model might be used to represent control behavior. This paper reports on the development of such a model to characterize the adaptation of pilot guidance to variations in aircraft dynamics using data obtained from a clinical pilot-in-the-loop flight simulation experiment. The results indicate that pilots tend to maintain a constant coupling between the dynamic system’s motion and the ττ guide across a range of different configuration parameters. Simultaneously, the pilot modulates the guidance maneuver period to adapt to these different aircraft dynamics that result in changes in workload. Modeling the complete pilot stabilization and guidance function as a regulator plus inverter yields good comparative results between the pilot–aircraft model and simulator trajectory data, and it supports the hypothesis that the following ττ-based guidance strategies suppress an aircraft’s natural dynamics

Load Loss Performance of an Autonomous Self-Excited Induction Generator

This paper presents a dynamic analysis of an autonomous Self-Excited Induction Generator (SEIG) showing dynamic loss of load performance. In stand-alone operation of the SEIG, especially when supplying a low power utility, an interesting performance of the SEIG observed for various power factor loads can be harnessed to maximise the use of the SEIG. Analysis is carried out based of the d-q axis model, while considering the performance characteristics of the machine at constant machine speed, capacitor value and for various power factor loads. The transient surge, its decay and rise on the various machine variables – phase voltage, phase current, capacitor current and load current are investigated for a gain and subsequent loss of load. The time it takes to excite the machine is also considered for the various power factors on an unloaded condition. The effects of the loading on the frequency, as well as the drop in the value of the monitored parameters are also investigated

Developing a Digital Twin at Building and City Levels: A Case Study of West Cambridge Campus

A digital twin (DT) refers to a digital replica of physical assets, processes, and systems. DTs integrate artificial intelligence, machine learning, and data analytics to create living digital simulation models that are able to learn and update from multiple sources as well as represent and predict the current and future conditions of physical counterparts. However, current activities related to DTs are still at an early stage with respect to buildings and other infrastructure assets from an architectural and engineering/construction point of view. Less attention has been paid to the operation and maintenance (O&M) phase, which is the longest time span in the asset life cycle. A systematic and clear architecture verified with practical use cases for constructing a DT would be the foremost step for effective operation and maintenance of buildings and cities. According to current research about multitier architectures, this paper presents a system architecture for DTs that is specifically designed at both the building and city levels. Based on this architecture, a DT demonstrator of the West Cambridge site of the University of Cambridge in the UK was developed that integrates heterogeneous data sources, supports effective data querying and analysis, supports decision-making processes in O&M management, and further bridges the gap between human relationships with buildings/cities. This paper aims at going through the whole process of developing DTs in building and city levels from the technical perspective and sharing lessons learned and challenges involved in developing DTs in real practices. Through developing this DT demonstrator, the results provide a clear roadmap and present particular DT research efforts for asset management practitioners, policymakers, and researchers to promote the implementation and development of DT at the building and city levels

Does timing of decisions in a mixed duopoly matter?

We determine the endogenous order of moves in a mixed pricesetting duopoly. In contrast to the existing literature on mixed oligopolies we establish the payo equivalence of the games with an exogenously given order of moves if the most plausible equilibrium is realized in the market. Hence, in this case it does not matter whether one becomes a leader or a follower. We also establish that replacing a private firm by a public firm in the standard Bertrand-Edgeworth game with capacity constraints increases social welfare and that a pure-strategy equilibrium always exists

Rotorcraft modeling renovation for improved fidelity

Copyright © 2019 by the Vertical Flight Society. All rights reserved. The research reported in this paper examines both established and new system identification techniques for rotorcraft flight-model renovation. Flight behavior models based on legacy aircraft are often the starting point for a new design and the fidelity, or model accuracy, can be validated when data are gathered in early flight testing of the new prototype. As data flow in, so flight models can be improved in fidelity, eventually supporting certification, provided the correct physics are embodied. System identification has become an established method for enhancing fidelity and suggesting causal relationships between flight and flight-model mismatches and missing physics. The objectives of our investigation include extending current system identification methods to address nonlinear model structures, and establishing appropriate approximations to the complex rotorcraft aeromechanics required to enhance fidelity, including maneuver wake distortion effects. The research is focused on renovation using Liverpool’s FLIGHTLAB Bell 412 simulation model based on data gathered on the National Research Council’s Advanced Systems Research Aircraft. We build on earlier work using frequency-domain methods, ideally suited to linear model structures and flight conditions sufficiently stable to allow control sweep data to be gathered. For hover and low-speed flight, strong nonlinearities caused by rotor-wake effects and significant deviations from the trim conditions, require a different approach and the paper shows how a new time-domain approach enables model structures and the parameters to be identified incrementally

The Need for Increased Fidelity in Flight Training Devices to address the ‘Rotorcraft Loss of Control Inflight’ problem

This paper examines the trends in rotorcraft accident statistics, particularly regarding Loss of Control In-flight accidents (LOC-I), with the aim of stimulating interest in new research relevant to this area. Despite recent safety initiatives, LOC-I rotorcraft accidents have been identified as a significant and growing contribution to accident rates. The fixed-wing commercial airline community faced a similar situation starting in the late 1990s and, through a coordinated international effort, developed a new training program to help reduce accident rates. Lessons learned from the fixed-wing work are presented to highlight the need for improved rotorcraft modeling tools to reduce rotorcraft accidents through higher-quality, simulator-based training programs. The findings from previous and ongoing rotorcraft modeling and simulation research are presented, and areas for further research are identified. A proposal is made in the paper for a workshop to bring together the key rotorcraft stakeholders to develop future steps in tackling rotorcraft LOC-I accidents

A pilot study comparing the metabolic profiles of elite-level athletes from different sporting disciplines

Background: The outstanding performance of an elite athlete might be associated with changes in their blood metabolic profile. The aims of this study were to compare the blood metabolic profiles between moderate- and high-power and endurance elite athletes and to identify the potential metabolic pathways underlying these differences. Methods: Metabolic profiling of serum samples from 191 elite athletes from different sports disciplines (121 high- and 70 moderate-endurance athletes, including 44 high- and 144 moderate-power athletes), who participated in national or international sports events and tested negative for doping abuse at anti-doping laboratories, was performed using non-targeted metabolomics-based mass spectroscopy combined with ultrahigh-performance liquid chromatography. Multivariate analysis was conducted using orthogonal partial least squares discriminant analysis. Differences in metabolic levels between high- and moderate-power and endurance sports were assessed by univariate linear models. Results: Out of 743 analyzed metabolites, gamma-glutamyl amino acids were significantly reduced in both high-power and high-endurance athletes compared to moderate counterparts, indicating active glutathione cycle. High-endurance athletes exhibited significant increases in the levels of several sex hormone steroids involved in testosterone and progesterone synthesis, but decreases in diacylglycerols and ecosanoids. High-power athletes had increased levels of phospholipids and xanthine metabolites compared to moderate-power counterparts. Conclusions: This pilot data provides evidence that high-power and high-endurance athletes exhibit a distinct metabolic profile that reflects steroid biosynthesis, fatty acid metabolism, oxidative stress, and energy-related metabolites. Replication studies are warranted to confirm differences in the metabolic profiles associated with athletes’ elite performance in independent data sets, aiming ultimately for deeper understanding of the underlying biochemical processes that could be utilized as biomarkers with potential therapeutic implications

Species specific anaesthetics for fish anaesthesia and euthanasia.

There is a need to ensure that the care and welfare for fish maintained in the laboratory are to the highest standards. This extends to the use of anaesthetics for both scientific study, humane killing and euthanasia at end of life. An anaesthetic should not induce negative behaviours and fish should not seek to avoid the anaesthetic. Surprisingly little information is available to facilitate a humane choice of anaesthetic agent for fish despite over 100 years of use and the millions of fish currently held in thousands of laboratories worldwide. Using a chemotaxic choice chamber we found different species specific behavioural responses among four closely related fish species commonly held in the laboratory, exposed to three widely used anaesthetic agents. As previously found for zebrafish (Danio rerio), the use of MS-222 and benzocaine also appears to induce avoidance behaviours in medaka (Oryzias latipes); but etomidate could provide an alternative choice. Carp (Cyprinus carpio), although closely related to zebrafish showed avoidance behaviours to etomidate, but not benzocaine or MS-222; and rainbow trout (Oncorhynchus mykiss) showed no avoidance to the three agents tested. We were unable to ascertain avoidance responses in fathead minnows (Pimephales promelas) and suggest different test paradigms are required for that species

Bridging topological and functional information in protein interaction networks by short loops profiling

Protein-protein interaction networks (PPINs) have been employed to identify potential novel interconnections between proteins as well as crucial cellular functions. In this study we identify fundamental principles of PPIN topologies by analysing network motifs of short loops, which are small cyclic interactions of between 3 and 6 proteins. We compared 30 PPINs with corresponding randomised null models and examined the occurrence of common biological functions in loops extracted from a cross-validated high-confidence dataset of 622 human protein complexes. We demonstrate that loops are an intrinsic feature of PPINs and that specific cell functions are predominantly performed by loops of different lengths. Topologically, we find that loops are strongly related to the accuracy of PPINs and define a core of interactions with high resilience. The identification of this core and the analysis of loop composition are promising tools to assess PPIN quality and to uncover possible biases from experimental detection methods. More than 96% of loops share at least one biological function, with enrichment of cellular functions related to mRNA metabolic processing and the cell cycle. Our analyses suggest that these motifs can be used in the design of targeted experiments for functional phenotype detection.This research was supported by the Biotechnology and Biological Sciences Research Council (BB/H018409/1 to AP, ACCC and FF, and BB/J016284/1 to NSBT) and by the Leukaemia & Lymphoma Research (to NSBT and FF). SSC is funded by a Leukaemia & Lymphoma Research Gordon Piller PhD Studentship

Id4 and FABP7 are preferentially expressed in cells with astrocytic features in oligodendrogliomas and oligoastrocytomas

BACKGROUND: Oligodendroglioma (ODG) and oligoastrocytoma (OAC) are diffusely infiltrating primary brain tumors whose pathogenesis remains unclear. We previously identified a group of genes whose expression was inversely correlated with survival in a cohort of patients with glioblastoma (GBM), and some of these genes are also reportedly expressed in ODG and OAC. We examined the expression patterns and localization of these survival-associated genes in ODG and OAC in order to analyze their possible roles in the oncogenesis of these two tumor types. METHODS: We used UniGene libraries derived from GBM and ODG specimens to examine the expression levels of the transcripts for each of the 50 GBM survival-associated genes. We used immunohistochemistry and cDNA microarrays to examine expression of selected survival-associated genes and Id4, a gene believed to control the timing of oligodendrocyte development. The expression of FABP7 and Id4 and the survival of patients with ODG and OAC were also analyzed. RESULTS: Transcripts of most survival-associated genes as well as Id4 were present in both GBM and ODG tumors, whereas protein expression of Id4 and one of the survival-associated genes, brain-type fatty acid-binding protein (FABP7), was present in cells with astrocytic features, including reactive and neoplastic astrocytes, but not in neoplastic oligodendrocytes. Id4 was co-expressed with FABP7 in microgemistocytes in ODG and in neoplastic astrocytes in OAC. Id4 and FABP7 expression, however, did not correlate with the clinical outcome of patients with ODG or OAC tumors. CONCLUSION: Expression of Id4 and some of our previously identified GBM survival-associated genes is present in developing or mature oligodendrocytes. However, protein expression of Id4 and FABP7 in GBM, ODG, and OAC suggests that this group of functionally important genes might demonstrate two patterns of expression in these glioma subtypes: one group is universally expressed in glioma cells, and the other group of genes is expressed primarily in neoplastic astrocytes but not in neoplastic oligodendrocytes. Differential protein expression of these two groups of genes in ODG and OAC may be related to the cellular origins and the histological features of the neoplastic cells