1,225 research outputs found

    Development of a pilot model suitable for the simulation of large aircraft

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    Effects of aeroservoelasticity on the manual control of large civil aircraft are investigated through a pilot modelling approach based on the modified optimal control model. A synopsis of modelling techniques is presented, followed by the description of the adopted technique. A simulation environment suitable for investigating pilot-vehicle dynamics in the longitudinal axis has been developed. The derivation of the pilot model was based on limiting the bandwidth. This approach showed that the pilot-vehicle system satisfied the crossover law between 3rad/s to 10rad/s for normal acceleration response. It was found that the pilot model and the low frequency tailplane bending mode introduced a resonant peak in the pilotvehicle frequency response that may be a cause for concern in high gain scenarios. Gust response simulations highlighted the contribution of fuselage bending mode on pilot perceived normal acceleration

    Neural network based dynamic model and gust identification system for the Jetstream G-NFLA

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    Artificial neural networks are an established technique for constructing non-linear models of multi-input-multi-output systems based on sets of observations. In terms of aerospace vehicle modelling, however, these are currently restricted to either unmanned applications or simulations, despite the fact that large amounts of flight data are typically recorded and kept for reasons of safety and maintenance. In this paper, a methodology for constructing practical models of aerospace vehicles based on available flight data recordings from the vehicles’ operational use is proposed and applied on the Jetstream G-NFLA aircraft. This includes a data analysis procedure to assess the suitability of the available flight databases and a neural network based approach for modelling. In this context, a database of recorded landings of the Jetstream G-NFLA, normally kept as part of a routine maintenance procedure, is used to form training datasets for two separate applications. A neural network based longitudinal dynamic model and gust identification system are constructed and tested against real flight data. Results indicate that in both cases, the resulting models’ predictions achieve a level of accuracy that allows them to be used as a basis for practical real-world applications

    Systematic literature survey: applications of LoRa communication

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    LoRa is a communication scheme that is part of the low power wide are network (LPWAN) technology using ISM bands. It has seen extensive documentation and use in research and industry due to its long coverage ranges of up-to 20Km or more with less than 14dB transmit power. Moreover, some applications report theoretical battery lives of upto 10years for field deployed modules utilising the scheme in WSN applications. Additionally, the scheme is very resilient to losses from noise, as well bursts of interference through its FEC. Our objective is to systematically review the empirical evidence of the use-cases of LoRa in rural landscapes, metrics and the relevant validation schemes. In addition the research is evaluated based on (i) mathematical function of the scheme (bandwidth use, spreading factor, symbol rate, chip rate and nominal bit rate) (ii) use-cases (iii) test-beds, metrics of evaluation and (iv) validation methods. A systematic literature review of published, refereed primary studies on LoRa applications was conducted. Using articles from 2010-2019. We identified 21 relevant primary studies. These reported a range of different assessments of LoRa. 10 out of 21 reported on novel use cases. As an actionable conclusion, the authors conclude that more work is needed in terms of field testing, as no articles could be found on performance/deployment in Botswana or South Africa despite the existence of LoRa networks in both countries. Thus researchers in the region can research propagation models performance, energy efficiency of the scheme and MAC layer as well as the channel access challenges for the region

    A Preliminary Limnological Investigation of Golden- Key Lake, Clemant Town, Uttranchal

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    The present study was undertaken to provide some baseline knowledge of the general limnology of Golden Key Lake, Clement town, which stands nearly unstudied artificial lake in Dehradun, India. The investigation was intended to get a coherent picture of the quantitative and qualitative aspects of the lake. This study was undertaken for a short period of time and therefore it should only constitute a starting point for studies imperative for management of these ecosystems of unique nature in the country. Four study sites were selected and analyzed for the main chemical variables and nutrients. An examination of the water chemistry data on comparative level revealed that both ions and nutrients were significantly higher at site I located at a point where sewage water without any treatment enters into the lake.  Computed on an average basis the inorganic elements have been found to follow the sequence: Ca > Na> Mg > K for sites I and II, while for sites III and IV, the sequence was: Ca> Mg>Na>K

    Mortality and use of psychotropic medication in patients with stroke:a population-wide, register-based study

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    OBJECTIVES: The study sought to describe whether psychotropic medication may have long-term side effects in patients with stroke compared with controls. SETTING: Use of national register data from healthcare services were identified from the Danish National Patient Registry in Denmark. Information about psychotropic medication use was obtained from the Danish Register of Medicinal Product Statistics. OBJECTIVES: We aimed to evaluate all-cause mortality in relation to the use of benzodiazepines, antidepressants and antipsychotics in patients with stroke and matched controls. PARTICIPANTS: Patients with a diagnosis of stroke and either no drug use or preindex use of psychotropic medication (n=49 968) and compared with control subjects (n=86 100) matched on age, gender, marital status and community location. PRIMARY OUTCOME MEASURE: All-cause mortality. RESULTS: All-cause mortality was higher in patients with previous stroke compared with control subjects. Mortality HRs were increased for participants prescribed serotonergic antidepressant drugs (HR=1.699 (SD=0.030), p=0.001 in patients; HR=1.908 (0.022), p<0.001 in controls, respectively), tricyclic antidepressants (HR=1.365 (0.045), p<0.001; HR=1.733 (0.022), p<0.001), benzodiazepines (HR=1.643 (0.040), p<0.001; HR=1.776 (0.053), p<0.001), benzodiazepine-like drugs (HR=1.776 (0.021), p<0.001; HR=1.547 (0.025), p<0.001), first-generation antipsychotics (HR=2.001 (0.076), p<0.001; HR=3.361 (0.159), p<0.001) and second-generation antipsychotics (HR=1.645 (0.070), p<0.001; HR=2.555 (0.086), p<0.001), compared with no drug use. Interaction analysis suggested statistically significantly higher mortality HRs for most classes of psychotropic drugs in controls compared with patients with stroke. CONCLUSIONS: All-cause mortality was higher in patients with stroke and controls treated with benzodiazepines, antidepressants and antipsychotics than in their untreated counterparts. Our findings suggest that care should be taken in the use and prescription of such drugs, and that they should be used in conjunction with adequate clinical controls

    Circadian consequences of social organization in the ant species Camponotus compressus

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    The locomotor activity rhythm of different castes of the ant species Camponotus compressus was monitored individually under laboratory light/dark (LD) cycles, and under continuous darkness (DD). The colony of this ant species comprises two sexual castes, the queens and the males, and three worker castes, namely the major, media, and minor workers. The virgin males and virgin queens display rhythmic activity patterns, but the mated queens were arrhythmic while laying eggs, with the rhythmicity resuming soon after egg-laying. Under the LD regime, major workers showed nocturnal patterns, while about 75% of the media workers displayed nocturnal patterns and about 25% showed diurnal patterns. Under the DD regime, most major workers exhibited circadian rhythm of activity with a single steady state, whereas media workers displayed two types of activity patterns, with activity patterns changing after 6-9 days in DD (turn-arounds). The pre-turn-around &#964; of the ants that showed nocturnal activity patterns during LD entrainment was &lt;24 h after release into DD, which then became &gt;24 h, after 6-9 days. On the other hand, the pre-turn-around &#964; of those ants that exhibited diurnal patterns during LD entrainment was first &gt;24 h after release into DD, and then became &lt;24 h, after 6-9 days. The activity of the minor workers neither entrained to LD cycles nor showed any sign of free-run in DD. It appears that the circadian clocks of the ant species C. compressus are flexible, and may perhaps depend upon the tasks assigned to them in the colony

    Allergic sensitization:host-immune factors

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    Allergic sensitization is the outcome of a complex interplay between the allergen and the host in a given environmental context. The first barrier encountered by an allergen on its way to sensitization is the mucosal epithelial layer. Allergic inflammatory diseases are accompanied by increased permeability of the epithelium, which is more susceptible to environmental triggers. Allergens and co-factors from the environment interact with innate immune receptors, such as Toll-like and protease-activated receptors on epithelial cells, stimulating them to produce cytokines that drive T-helper 2-like adaptive immunity in allergy-prone individuals. In this milieu, the next cells interacting with allergens are the dendritic cells lying just underneath the epithelium: plasmacytoid DCs, two types of conventional DCs (CD11b + and CD11b-), and monocyte-derived DCs. It is now becoming clear that CD11b+, cDCs, and moDCs are the inflammatory DCs that instruct naïve T cells to become Th2 cells. The simple paradigm of non-overlapping stable Th1 and Th2 subsets of T-helper cells is now rapidly being replaced by that of a more complex spectrum of different Th cells that together drive or control different aspects of allergic inflammation and display more plasticity in their cytokine profiles. At present, these include Th9, Th17, Th22, and Treg, in addition to Th1 and Th2. The spectrum of co-stimulatory signals coming from DCs determines which subset-characteristics will dominate. When IL-4 and/or IL-13 play a dominant role, B cells switch to IgE-production, a process that is more effective at young age. IgE-producing plasma cells have been shown to be long-lived, hiding in the bone-marrow or inflammatory tissues where they cannot easily be targeted by therapeutic intervention. Allergic sensitization is a complex interplay between the allergen in its environmental context and the tendency of the host’s innate and adaptive immune cells to be skewed towards allergic inflammation. These data and findings were presented at a 2012 international symposium in Prague organized by the Protein Allergenicity Technical Committee of the International Life Sciences Institute’s Health and Environmental Sciences Institute
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